JP2007095218A - Optical disk device - Google Patents

Abstract

An optical disc apparatus that reliably controls focus on a target layer of an optical disc medium composed of a plurality of layers is provided.
An operation for performing focus control on the target layer is performed in a state in which spherical aberration is corrected by the thickness of the equipment up to the target layer. If the focus is accidentally drawn into a layer other than the intended layer, the thickness of the equipment is different, so that spherical aberration occurs, resulting in a large deviation from the level and balance of the signal that should be output. By using this deviation, it is detected that it has been accidentally drawn into a layer other than the intended layer. As a signal for detection, an addition signal, a tracking error signal, a reproduction signal or the like is used. Further, by using these versatile signals, detection is possible only by using a conventional circuit without requiring a special circuit. If it is detected that the lens has been drawn by mistake, the operation of drawing the focus into the target layer is performed again.
[Selection] Figure 1

Description

  The present invention relates to an optical disc apparatus for recording, reproducing or erasing information on an optical disc as an optical information medium.

  Optical memory technology using optical disks with pit-like patterns as high-density, large-capacity storage media is practically used while expanding applications such as digital versatile discs (DVD), video discs, document file discs, and data files. It is becoming. The function required for the successful recording / reproduction of information on an optical disc through a finely focused light beam (for example, 1 μm or less in diameter) is the diffraction limit. These are roughly classified into a condensing function for forming a minute spot, a focus control function (focus servo) and tracking control function for a minute spot of an optical system, and a pit signal (information signal) detection function.

  As described in (Patent Literature 1) and (Patent Literature 2), in recent years, in order to further increase the recording density of an optical disc, a light spot is converged on the optical disc to form a diffraction-limited spot. Increasing the numerical aperture (NA) of the objective lens is being studied. However, since the spherical aberration caused by the error in the thickness of the base material protecting the recording layer of the optical disk is proportional to the fourth power of NA, for example, when NA is increased to 0.8, 0.85, etc., the spherical aberration is It will grow dramatically. Therefore, it is essential to provide means for correcting spherical aberration in the optical system. An example is shown in FIG. This is referred to as spherical aberration correcting means example 1.

  In the optical pickup 11 shown in FIG. 14, reference numeral 1 denotes a radiation light source such as a laser light source. The light beam 10 (laser light) emitted from the laser light source 1 is converted into parallel light by the collimator lens 3, passes through the liquid crystal aberration correction element 4, enters the objective lens 5, and is incident on the information recording surface of the optical disk 6. Converged. The light beam reflected by the optical disk 6 is converged by the collimator lens 3 along the original optical path, and is guided to the photodetectors 8 and 9 by the light branching means such as the diffractive element 2. Servo signals (focus error signal and tracking error signal) and information signals are generated from the output signals of the photodetectors 8 and 9. Here, the NA of the objective lens 5 is a large one of 0.8 or more. The actuator 7 performs focus control, which is position control of the objective lens 5 in the optical axis direction, and tracking control, which is position control in a direction perpendicular to the focus control, and is configured by driving means such as a coil and a magnet.

  Although not shown in the drawing, a transparent base material is provided on the surface of the information recording surface of the optical disc 6 on the objective lens 5 side, and plays a role in protecting information. Since the error in the thickness and refractive index of the transparent base material causes spherical aberration, it is the role of the liquid crystal aberration correction element 4 to correct the wavefront of the light beam so that the reproduction signal becomes the best. The liquid crystal aberration correction element 4 is formed with a pattern of a transparent electrode such as indium-tin-oxide alloy (ITO, Indium Tin Oxide). By applying a voltage to the transparent electrode, the liquid crystal aberration correction element 4 The refractive index distribution in the surface is controlled to modulate the wavefront of the light beam. FIG. 15 shows an optical disk apparatus using another means for correcting spherical aberration.

  FIG. 15 omits the laser light source, the collimating lens, and the photodetector from the optical system of the optical pickup. The light beam that has been collimated by the collimator lens passes through the aberration correction lens group 201 including the negative lens group 21 and the positive lens group 22, and is applied to the optical disk 6 by the objective lens group 202 including the objective lens 302 and the front lens 301. To converge. In the aberration correction lens group 201, the spherical aberration of the entire optical system is corrected by changing the distance between the negative lens group 21 and the positive lens group 22. The distance between the negative lens group 21 and the positive lens group 22 can be changed by, for example, the drive unit 25 that moves the negative lens group 21 in the optical axis direction. The drive unit 25 can be realized by using, for example, a voice coil, a piezo element, an ultrasonic motor, or a screw feed.

  FIG. 16 is a block diagram of an optical disc apparatus using means for correcting spherical aberration. This will be referred to as spherical aberration correcting means example 2. The optical disk apparatus of this embodiment includes the same optical pickup 11 as that in FIG. 14 of the spherical aberration correcting means example 1 described above, the aberration correcting element driving means 26 for driving the liquid crystal aberration correcting element 4 as the aberration correcting means, and the optical pickup 11. The control circuit 118 for receiving the signal obtained from the optical disc 5 and driving the objective lens 5, the disc discriminating means 12 for discriminating the type of the optical disc, and the liquid crystal aberration correcting element by the disc discriminating signal 13 which is the output of the disc discriminating device 4 comprises an aberration correction amount switching means 14 for selecting and switching the spherical aberration correction amount to be corrected in step 4.

The configuration of the optical pickup 11 is the same as that described with reference to FIG. 14, and the same components as those in FIG.
The aberration correction amount switching means 14 of the spherical aberration correction means example 2 will be described.

  For example, the base material thickness of the reference disk is 100 μm. The aberration correction amount switching means 14 includes an aberration correction amount (a) (spherical aberration correction amount 0 mλ), an aberration correction amount (b) (spherical aberration correction when correcting an optical disc whose substrate thickness is 10 μm thinner than the reference disc. Amount) and aberration correction amount (c) (spherical aberration correction amount when correcting an optical disk whose substrate thickness is 10 μm thick with respect to the reference disk) are set in advance. Among these aberration correction amounts, an appropriate spherical aberration correction amount is selected and switched according to the disc discrimination signal 13 from the disc discrimination means 12.

FIG. 17 shows an optical disc 75 having two recording layers.
The optical disk 75 shown in FIG. 17 has a base 76, an L0 layer (first recording layer) 77, an intermediate layer 78, an L1 layer (second recording layer) 79, and a protective layer 80 on the back surface in this order from the optical pickup side. It is configured. The base material 76 and the intermediate layer 78 are made of a transparent material such as resin, and the thicknesses from the surface on the optical pickup side of the optical disc 75 to the L0 layer and the L1 layer are 0.09 mm and 0.11 mm, respectively.

Next, the spherical aberration correction procedure in the form of the spherical aberration correction means example 2 will be described.
The spherical aberration correction operation can be started, for example, when an optical disk is mounted on the optical disk apparatus or when the optical disk apparatus is turned on. First, the type of the optical disc is discriminated by the disc discriminating means 12. When the disc discriminating unit 12 determines that the optical disc has two recording layers (optical disc 75) and the focus control is performed on the L0 layer 77, the aberration correction amount switching unit 14 is instructed by the disc discriminating signal 13 command. Then, the aberration correction amount (b) is selected, and the spherical aberration corresponding to 10 μm is corrected by the aberration correction lens group 201 on the side where the substrate thickness error with respect to the reference disk is thin. As a result, a stable focus error signal can be obtained in the focus control performed on the L0 layer 77 thereafter.

  Similarly, when the disc discriminating means 12 judges that the optical disc has two recording layers (optical disc 75) and the focus control is performed on the L1 layer 79, the aberration correction amount is instructed by the disc discrimination signal 13 command. The aberration correction amount (c) is selected by the switching means 14, and spherical aberration corresponding to 10 μm is corrected by the aberration correction lens group 201 on the side where the substrate thickness error with respect to the reference disk is thick. As a result, a stable focus error signal can be obtained in the focus control performed on the L1 layer 79 thereafter.

The optical disc apparatus of the above-described form is characterized in that spherical aberration correction is performed in advance on the recording surface of the optical disc on which focus control is performed before the focus control is operated.
JP 2002-373441 A Japanese Patent Laid-Open No. 2004-247047

  However, such a configuration is based on the premise that the focus is drawn without making a mistake in the target layer, and no assumption is made if the focus is accidentally drawn in a layer other than the target layer. Even if the focus is accidentally drawn to a layer other than the target due to some influence (for example, vibration or shock applied to the device during the focus pull to the target layer), the target layer is correctly drawn. Therefore, the servo control is performed on the wrong layer, and the operation to read the data recorded on the optical disk or to write the data on the optical disk is performed. When attempting to read data in the wrong layer, aberration control has occurred and servo control becomes unstable, and data cannot be read normally. Even in such a state, many retries are performed in order to read data. Normally, if there is a limit on the number of retries, or if the time that cannot be read has exceeded a certain amount of time, it will be judged that it has been drawn into the wrong layer, and it will be redrawn to the target layer, but after it has been drawn into the wrong layer It takes a considerable time until it is actually judged as an error. Further, when no retry process is provided, a read error occurs, and eventually the read fails. In addition, if data is to be recorded in the wrong layer, data cannot be recorded normally because the recording operation is performed in a state where aberration is occurring.

  Therefore, when focus control of a minute spot is performed on an optical disc having two or more information recording layers, whether or not the focus is definitely drawn for each target information recording layer or wrongly. It is essential to be able to detect whether the focus is drawn to a layer other than the target. For this reason, in order to correctly access a specific information recording layer in a multilayer optical disk using an objective lens having a high numerical aperture such as NA = 0.85, an appropriate method for determining a layer is desired.

  In view of these circumstances, an object of the present invention is to enable appropriate focus control with respect to an information recording layer of a multi-layer recording medium. A method suitable for use is provided.

  The first optical disk apparatus of the present invention is an optical disk apparatus that accesses an optical recording medium having a plurality of information recording layers, and moves a condensing optical system that converges to a minute spot onto the optical recording medium in the optical axis direction. And an optical pickup having a light beam reflected from the optical recording medium and a light detector that outputs an electric signal in accordance with the amount of light, and the optical recording based on an output signal from the light detector. A focus error detecting means for detecting a convergence state of the minute spot converged on the medium, and driving the focus moving means based on an output signal from the focus error detecting means to detect the minute spot on the optical recording medium. Actuator driving means for controlling the convergence state and the minute spot converged on the optical recording medium based on the output from the photodetector. And a tracking error detecting means for detecting a relative deviation state between a track provided on the optical recording medium and a tracking error for detecting an amplitude of a tracking error signal based on an output from the tracking error detecting means Signal amplitude detection means, tracking error signal amplitude comparison means for comparing the signal amplitude detected by the tracking error signal amplitude detection means with a comparison reference value, and a threshold value for storing a comparison reference value to be given to the tracking error signal amplitude comparison means A storage unit, a layer determination unit for detecting whether the minute spot has converged on a target layer or a layer other than the target from the output of the tracking error signal amplitude comparison unit, and an optical recording medium. From the layer determining means, the converged minute spot converges to a target layer. Characterized in that a control means for controlling the focus movement unit by the actuator driving unit based on the output.

  In the first optical disc apparatus of the present invention, the value stored in the threshold value storage means is the magnitude of the signal amplitude detected by the tracking error signal amplitude detection means after the minute spot has converged on the target layer. It is characterized by having learned and corrected from.

  Further, in the first optical disc apparatus of the present invention, the value stored in the threshold value storage means is the magnitude of the signal amplitude detected by the tracking error signal amplitude detection means after the minute spot has converged on the target layer, The magnitude of the signal amplitude detected by the tracking error signal amplitude detecting means when the correction amount of the aberration correcting means for correcting the spherical aberration of the condensing optical system of the pickup is set to an optimum correction amount other than the target layer. It is characterized by having comprised so that it may determine based on.

  The second optical disk apparatus of the present invention is an optical disk apparatus that accesses an optical recording medium having a plurality of information recording layers, and moves a condensing optical system that converges to a minute spot onto the optical recording medium in the optical axis direction. And an optical pickup having a light beam reflected by the optical recording medium and a light detector that outputs an electric signal according to the amount of light, and the optical recording based on an output signal from the light detector. A focus error detecting means for detecting a convergence state of the minute spot converged on the medium, and driving the focus moving means based on an output signal from the focus error detecting means to detect the minute spot on the optical recording medium. Actuator driving means for controlling the convergence state and the minute spot converged on the optical recording medium based on the output from the photodetector. And a tracking error detecting means for detecting a relative deviation state between a track provided on the optical recording medium and a tracking error for detecting a level of a tracking error signal based on an output from the tracking error detecting means Signal level detection means, tracking error signal level comparison means for comparing the signal level detected by the tracking error signal level detection means with a comparison reference value, and a threshold value for storing a comparison reference value to be given to the tracking error signal level comparison means A storage unit; a layer determination unit that detects whether the minute spot has converged on a target layer or a layer other than the target from an output from the tracking error signal level comparison unit; and an optical recording medium So that the minute spot converged on the target layer converges on the target layer By the actuator driving unit based on the output from the serial layer determining means, characterized in that a control means for controlling said focus moving means.

  In the second optical disc apparatus of the present invention, the value stored in the threshold value storage means is learned from the signal level detected by the tracking error signal level detection means after the minute spot has converged on the target layer. It is characterized by having comprised so that it may correct | amend.

  In the second optical disc apparatus of the present invention, the value stored in the threshold value storage means is a signal level detected by the tracking error signal level detection means after the minute spot has converged on a target layer, It is determined based on the signal level detected by the tracking error signal level detection means when the correction amount of the aberration correction means for correcting the spherical aberration of the condensing optical system is set to an optimum correction amount other than the target layer. It is characterized by having comprised as follows.

  A third optical disk apparatus of the present invention is an optical disk apparatus for accessing an optical recording medium having a plurality of information recording layers, and moves a condensing optical system that converges to a minute spot on the optical recording medium in the optical axis direction. And an optical pickup having a light beam reflected by the optical recording medium and a light detector that outputs an electric signal according to the amount of light, and the optical recording based on an output signal from the light detector. A focus error detecting means for detecting a convergence state of the minute spot converged on the medium, and driving the focus moving means based on an output signal from the focus error detecting means to detect the minute spot on the optical recording medium. Actuator driving means for controlling the convergence state and the minute spot converged on the optical recording medium based on the output from the photodetector. Tracking error detecting means for detecting a relative deviation state between the optical recording medium and a track provided on the optical recording medium, and tracking for detecting a balance value of the tracking error signal based on an output from the tracking error detecting means The error signal balance value detecting means, the tracking error signal balance value comparing means for comparing the signal balance value detected by the tracking error signal balance value detecting means with a comparison reference value, and the tracking error signal balance value comparing means Threshold storage means for storing a comparison reference value, and layer determination means for detecting whether the minute spot has converged on a target layer or a layer other than the target from the output of the tracking error signal balance value comparison means And the minute spots converged on the optical recording medium Characterized in that a control means for controlling the focus movement unit by the actuator driving unit based on an output from the layer determining means to converge to the layer.

  In the third optical disc apparatus of the present invention, the value stored in the threshold value storage means is the magnitude of the signal amplitude detected by the tracking error signal balance value detection means after the minute spot has converged on the target layer. It is characterized in that it is configured to learn and correct.

  In the third optical disc apparatus of the present invention, the value stored in the threshold value storage means is a balance value detected by the tracking error signal balance value detection means after the minute spot has converged on a target layer, and a pickup. Based on the balance value detected by the tracking error signal balance value detecting means when the correction amount of the aberration correcting means for correcting the spherical aberration of the condensing optical system is set to an optimum correction amount other than the target layer It is characterized by having comprised so that it may determine.

  A fourth optical disk apparatus of the present invention is an optical disk apparatus that accesses an optical recording medium having a plurality of information recording layers, and moves a condensing optical system that converges to a minute spot onto the optical recording medium in the optical axis direction. And an optical pickup having a light beam reflected from the optical recording medium and a light detector that outputs an electric signal in accordance with the amount of light, and the optical recording based on an output signal from the light detector. A focus error detecting means for detecting a convergence state of the minute spot converged on the medium, and driving the focus moving means based on an output signal from the focus error detecting means to detect the minute spot on the optical recording medium. Actuator driving means for controlling the convergence state and the minute spot converged on the optical recording medium based on the output from the photodetector. And a tracking error detecting means for detecting a relative deviation state between the optical recording medium and a track provided on the optical recording medium, and detecting a deviation between a tracking error amplitude of the output from the tracking error detecting means and a target amplitude. The tracking error signal AGC detection means, the tracking error signal AGC value comparison means for comparing the magnitude of the control signal detected by the tracking error signal AGC detection means with a comparison reference value, and the tracking error signal AGC value comparison means Threshold storage means for storing a comparison reference value, and layer determination for detecting whether the minute spot has converged on a target layer or a layer other than the target from the output of the tracking error signal AGC value comparison means And the minute spot converged on the optical recording medium is a target. Characterized in that a control means for controlling the focus movement unit by the actuator driving unit based on an output from the layer determining means to converge to.

  In the fourth optical disk device, the value stored in the threshold value storage means is corrected by learning from the control signal detected by the tracking error signal AGC detection means after the minute spot has converged on the target layer. It is characterized by having comprised as follows.

  In the fourth optical disc apparatus of the present invention, the value stored in the threshold value storage means may be a control signal detected by the tracking error signal AGC detection means after the minute spot converges on a target layer, This is determined based on the control signal detected by the tracking error signal AGC detecting means when the correction amount of the aberration correcting means for correcting the spherical aberration of the condensing optical system is set to an optimum correction amount other than the target layer. It is characterized by having comprised as follows.

  In the fourth optical disc apparatus of the present invention, there is provided tracking error signal amplifying means for amplifying the tracking error amplitude of the output from the tracking error detecting means based on a control signal from the tracking error signal AGC detecting means, The output signal of the tracking error signal amplifying means is inputted to the control means.

  The fifth optical disk apparatus of the present invention is an optical disk apparatus that accesses an optical recording medium having a plurality of information recording layers, and moves a condensing optical system that converges to a minute spot onto the optical recording medium in the optical axis direction. And an optical pickup having a light beam reflected by the optical recording medium and a light detector that outputs an electric signal according to the amount of light, and the optical recording based on an output signal from the light detector. A focus error detecting means for detecting a convergence state of the minute spot converged on the medium, and driving the focus moving means based on an output signal from the focus error detecting means to detect the minute spot on the optical recording medium. Actuator driving means for controlling the convergence state, addition signal generation means for generating a sum signal of the outputs from the photodetector, and the addition signal generation Addition signal level detection means for detecting the level of the addition signal at the output of the means, addition signal level comparison means for comparing the signal level detected by the addition signal level detection means with a comparison reference value, and the addition signal level comparison means Threshold value storage means for storing a comparison reference value given to the output signal and an output from the added signal level comparison means detects whether the minute spot has converged on a target layer or a layer other than the target layer Layer determining means and control means for controlling the focus moving means by the actuator driving means based on an output from the layer determining means so that the minute spot converged on the optical recording medium converges on a target layer And is provided.

  In the fifth optical disc apparatus of the present invention, the value stored in the threshold value storage means is corrected by learning from the signal detected by the addition signal level detection means after the minute spot has converged on the target layer. It is characterized by having comprised.

  In the fifth optical disc apparatus of the present invention, the value stored in the threshold value storage means is the signal level detected by the addition signal level detection means after the minute spot has converged on the target layer, and the pickup The aberration correction means for correcting the spherical aberration of the condensing optical system is determined based on the signal level detected by the addition signal level detection means when the correction amount of the aberration correction means is set to an optimum correction amount other than the target layer. It is characterized by that.

  A sixth optical disk apparatus of the present invention is an optical disk apparatus that accesses an optical recording medium having a plurality of information recording layers, and moves a condensing optical system that converges to a minute spot onto the optical recording medium in the optical axis direction. And an optical pickup having a light beam reflected by the optical recording medium and a light detector that outputs an electric signal according to the amount of light, and the optical recording based on an output signal from the light detector. A focus error detecting means for detecting a convergence state of the minute spot converged on the medium, and driving the focus moving means based on an output signal from the focus error detecting means to detect the minute spot on the optical recording medium. Actuator driving means for controlling the convergence state, addition signal generation means for generating a sum signal of the output from the photodetector, and the addition signal generation Addition signal AGC detection means for detecting a deviation between the output amplitude of the means and the target amplitude, addition signal AGC value comparison means for comparing the amplitude detected by the addition signal AGC detection means with a comparison reference value, and the addition signal Threshold storage means for storing a comparison reference value to be given to the AGC value comparison means, and whether the minute spot has converged on a target layer or a layer other than the target from the output of the addition signal AGC value comparison means And the focus moving unit is controlled by the actuator driving unit based on an output from the layer determining unit so that the minute spot converged on the optical recording medium converges on a target layer. And a control means for providing the control means.

  In the sixth optical disc device of the present invention, the value stored in the threshold value storage means is learned and corrected from the signal detected by the addition signal AGC detection means after the minute spot has converged on the target layer. It is characterized by having comprised.

  In the sixth optical disc device of the present invention, the value stored in the threshold value storage means is the signal level detected by the addition signal AGC detection means after the minute spot has converged on the target layer, and the pickup It is determined based on the signal level detected by the addition signal AGC detection means when the correction amount of the aberration correction means for correcting the spherical aberration of the condensing optical system is set to an optimum correction amount other than the target layer. It is characterized by that.

  In the sixth optical disk apparatus of the present invention, addition signal amplification means for amplifying the addition signal amplitude of the output from the addition signal generation means based on a control signal from the addition signal AGC detection means is provided, and this addition signal The output signal of the amplification means is inputted to the control means.

  A seventh optical disk apparatus of the present invention is an optical disk apparatus that accesses an optical recording medium having a plurality of information recording layers, and moves a condensing optical system that converges to a minute spot onto the optical recording medium in the optical axis direction. And an optical pickup having a light beam reflected by the optical recording medium and a light detector that outputs an electric signal according to the amount of light, and the optical recording based on an output signal from the light detector. A focus error detecting means for detecting a convergence state of the minute spot converged on the medium, and driving the focus moving means based on an output signal from the focus error detecting means to detect the minute spot on the optical recording medium. Actuator driving means for controlling the convergence state, and RF signal generating means for extracting a reproduction signal generated based on the output from the photodetector RF signal amplitude detection means for detecting the amplitude of the reproduction signal based on the output from the RF signal generation means, and RF signal amplitude comparison for comparing the signal amplitude detected by the RF signal amplitude detection means with a comparison reference value Means, a threshold value storage means for storing a comparison reference value to be given to the RF signal amplitude comparison means, and whether the minute spot has converged on the target layer or not on the target layer from the output of the RF signal amplitude comparison means A layer determining means for detecting whether or not the focusing is performed by the actuator driving means based on an output from the layer determining means so that the minute spot converged on the optical recording medium converges on a target layer. Control means for controlling the moving means is provided.

  In the seventh optical disc device of the present invention, the value stored in the threshold value storage means is corrected by learning from the signal detected by the RF signal amplitude detection means after the minute spot has converged on the target layer. It is characterized by having comprised.

  In the seventh optical disc apparatus of the present invention, the value stored in the threshold value storage means is the amplitude detected by the RF signal amplitude detection means after the minute spot has converged on the target layer, and the collection of pickups. The correction is made based on the amplitude detected by the RF signal amplitude detection means when the correction amount of the aberration correction means for correcting the spherical aberration of the optical optical system is set to an optimum correction amount other than the target layer. It is characterized by.

  An eighth optical disk apparatus of the present invention is an optical disk apparatus for accessing an optical recording medium having a plurality of information recording layers, and moves a condensing optical system that converges to a minute spot onto the optical recording medium in the optical axis direction. And an optical pickup having a light beam reflected by the optical recording medium and a light detector that outputs an electric signal according to the amount of light, and the optical recording based on an output signal from the light detector. A focus error detecting means for detecting a convergence state of the minute spot converged on the medium, and driving the focus moving means based on an output signal from the focus error detecting means to detect the minute spot on the optical recording medium. Actuator driving means for controlling the convergence state, and RF signal generating means for extracting a reproduction signal generated based on the output from the photodetector RF signal level detection means for detecting the level of the reproduction signal based on the output from the RF signal generation means, and RF signal level comparison for comparing the signal level detected by the RF signal level detection means with a comparison reference value Means, threshold value storage means for storing a comparison reference value to be given to the RF signal level comparison means, and whether the minute spot has converged on the target layer or not on the target layer by the output from the RF signal level comparison means Layer determining means for detecting whether the light is converged, and the actuator driving means based on the output from the layer determining means so that the minute spot converged on the optical recording medium converges on a target layer. Control means for controlling the focus moving means is provided.

  In the eighth optical disc device of the present invention, the value stored in the threshold value storage means is corrected by learning from the signal detected by the RF signal level detection means after the minute spot has converged on the target layer. It is characterized by having comprised.

  In the eighth optical disc apparatus of the present invention, the value stored in the threshold value storage means is the signal level detected by the RF signal level detection means after the minute spot has converged on the target layer, and the pickup The aberration correction means for correcting the spherical aberration of the condensing optical system is determined based on the signal level detected by the RF signal level detection means when the correction amount other than the target layer is set to an optimal correction amount. It is characterized by that.

  A ninth optical disk apparatus of the present invention is an optical disk apparatus that accesses an optical recording medium having a plurality of information recording layers, and moves a condensing optical system that converges to a minute spot onto the optical recording medium in the optical axis direction. And an optical pickup having a light beam reflected by the optical recording medium and a light detector that outputs an electric signal according to the amount of light, and the optical recording based on an output signal from the light detector. A focus error detecting means for detecting a convergence state of the minute spot converged on the medium, and driving the focus moving means based on an output signal from the focus error detecting means to detect the minute spot on the optical recording medium. Actuator driving means for controlling the convergence state, and RF signal generating means for extracting a reproduction signal generated based on the output from the photodetector An RF signal jitter detecting means for detecting a jitter value of the reproduction signal based on an output from the RF signal generating means, and a jitter value detected by the RF signal jitter detecting means is smaller than a predetermined jitter value. An RF signal jitter value comparing means for comparing whether or not, a threshold value storing means for storing a comparison reference value to be given to the RF signal jitter value comparing means, and an output from the RF signal jitter value comparing means to target the minute spot Layer determining means for detecting whether the light beam has converged on a layer other than the target layer, and the layer determination so that the minute spot converged on the optical recording medium converges on the target layer And a control means for controlling the focus moving means by the actuator driving means based on an output from the means.

  In the ninth optical disc apparatus of the present invention, the value stored in the threshold value storage means is corrected by learning from the signal detected by the RF signal jitter detection means after the minute spot has converged on the target layer. It is characterized by having comprised.

  In the ninth optical disc apparatus of the present invention, the value stored in the threshold value storage means is the signal level detected by the RF signal jitter detection means after the minute spot has converged on the target layer, and the pickup A configuration for determining based on the signal level detected by the RF signal jitter detecting means when the correction amount of the aberration correcting means for correcting the spherical aberration of the condensing optical system is set to an optimum correction amount other than the target layer. It is characterized by that.

  A tenth optical disk apparatus of the present invention is an optical disk apparatus for accessing an optical recording medium having a plurality of information recording layers, and moves a condensing optical system that converges to a minute spot on the optical recording medium in the optical axis direction. And an optical pickup having a light beam reflected from the optical recording medium and a light detector that outputs an electric signal in accordance with the amount of light, and the optical recording based on an output signal from the light detector. A focus error detecting means for detecting a convergence state of the minute spot converged on the medium, and driving the focus moving means based on an output signal from the focus error detecting means to detect the minute spot on the optical recording medium. Actuator driving means for controlling the convergence state, and RF signal generation for extracting a reproduction signal generated based on the output from the photodetector An RF envelope signal detecting means for detecting an envelope of a reproduction signal based on an output from the RF signal generating means, and an RF envelope level for comparing the envelope value detected by the RF envelope signal detecting means with a comparison reference value A comparison means, a threshold value storage means for storing a comparison reference value to be given to the RF envelope level comparison means, and whether the minute spot has converged on the target layer or not by the output from the RF envelope signal detection means By means of the actuator driving means based on the output from the layer judging means so that the minute spot converged on the optical recording medium converges on the target layer. Control means for controlling the focus moving means is provided.

  In the tenth optical disc apparatus of the present invention, the value stored in the threshold value storage means is corrected by learning from the signal detected by the RF envelope signal detection means after the minute spot has converged on the target layer. It is characterized by having comprised.

  In the tenth optical disc apparatus of the present invention, the value stored in the threshold value storage means may be a value detected by the RF envelope signal detection means after the minute spot has converged on a target layer, and the collection of pickups. The correction is made based on the value detected by the RF envelope signal detection means when the correction amount of the aberration correction means for correcting the spherical aberration of the optical optical system is set to an optimum correction amount other than the target layer. It is characterized by.

  An eleventh optical disk apparatus of the present invention is an optical disk apparatus that accesses an optical recording medium having a plurality of information recording layers, and moves a condensing optical system that converges to a minute spot onto the optical recording medium in the optical axis direction. And an optical pickup having a light beam reflected by the optical recording medium and a light detector that outputs an electric signal according to the amount of light, and the optical recording based on an output signal from the light detector. A focus error detecting means for detecting a convergence state of the minute spot converged on the medium, and driving the focus moving means based on an output signal from the focus error detecting means to detect the minute spot on the optical recording medium. Actuator driving means for controlling the convergence state, and RF signal generation for extracting a reproduction signal generated based on the output from the photodetector And an RF signal AGC detection means for detecting a deviation between an amplitude of a reproduction signal output from the RF signal generation means and a target amplitude, and a control signal detected by the RF signal AGC detection means is compared with a comparison reference value. RF signal AGC value comparison means, threshold value storage means for storing a comparison reference value to be given to the RF signal AGC value comparison means, and output from the RF signal AGC value comparison means, the minute spot converges on a target layer. Layer determining means for detecting whether the light spot is converged on a layer other than the target, and an output from the layer determining means so that the minute spot converged on the optical recording medium converges on the target layer. And a control means for controlling the focus moving means by the actuator driving means.

  In the eleventh optical disc apparatus, the value stored in the threshold value storage means is corrected by learning from the signal detected by the RF signal AGC detection means after the minute spot has converged on a target layer. It is characterized by that.

  In the eleventh optical disk apparatus, the value stored in the threshold value storage means is a value detected by the RF signal AGC detection means after the minute spot has converged on a target layer, and the condensing optical system of the pickup. The correction amount of the aberration correction means for correcting the spherical aberration is determined based on the value detected by the RF signal AGC detection means when the correction amount other than the target layer is an optimum correction amount. To do.

  In the eleventh optical disk apparatus, RF signal amplifying means for amplifying the added signal amplitude of the output from the RF signal generating means based on a control signal from the RF signal AGC detecting means is provided. An output signal is input to the control means.

  According to the first to eleventh optical disc apparatuses of the present invention, when recording or reproducing is performed on a high-density optical disc using an objective lens having a large NA, the disc surface to the recording surface viewed from the recording surface is recorded. With the spherical aberration due to the layer thickness corrected, the actuator driving means is operated to focus the minute spot on the target layer. At this time, it can be determined whether the minute spot is focused on the target layer or whether the minute spot is focused on a layer other than the target, and if the minute spot is focused on a layer other than the target In this case, it is possible to stably record or reproduce the optical disc by quickly performing focus control on the target layer.

  In addition, since an existing circuit can be used without adding a new circuit, the system can be realized without increasing wasteful cost.

Hereinafter, the present invention will be described based on each embodiment.
(Embodiment 1)
FIG. 1 shows an optical disc apparatus according to Embodiment 1 of the present invention.

  The optical disk apparatus according to the present embodiment includes the same optical pickup 11 as in FIG. 14 described in the conventional example, an aberration correction element driving unit 26 that drives the liquid crystal aberration correction element 4 as an aberration correction unit, and at least two or more pluralities. Aberration correction amount storage means 31 for storing the aberration correction amount for each layer of the optical disk 6 composed of a plurality of layers, an actuator drive means 38 for driving the objective lens 5, and a signal obtained from the optical pickup 11 are converged on the optical disk 6. Focus error detecting means 32 for detecting the convergence state of the minute spot that has been detected, and tracking error detection means for detecting the relative positional deviation between the minute spot converged on the optical disk 6 and the track on the optical disk 6 33, an output signal from the focus error detection means 32, and a tracking error detection means 33 The actuator driving means 38 for driving the objective lens 5 for converging the laser beam on the disk based on the output signal, and the tracking error signal amplitude for detecting the amplitude of the tracking error signal based on the output signal from the tracking error detecting means 33 Output from the detection means 35, the tracking error signal amplitude comparison means 36 for comparing the signal from the tracking error signal amplitude detection means 35 with the threshold value stored in the threshold value storage means 34, and the tracking error signal amplitude comparison means 36. Based on the result, the actuator determines whether the minute spot has converged on the target layer, and if the minute spot is focused on a layer other than the target, the actuator is used to focus the minute spot on the target layer. The actuator driving means 38 is instructed to drive 7 The type of the optical disk is discriminated based on the output from the determination means 37 and the photodetectors 8 and 9, the signal from the focus error detection means 32, and the signal from the tracking error detection means 33, and the laser light source 1 emits light. Control the actuator drive means 38, drive the aberration correction element drive means 26 to improve the information signal obtained from the optical pickup 11, and further, based on the signal from the layer determination means 37, When the focus is drawn into a layer other than the target, the control means 39 for performing a process of drawing the focus into the target layer again is provided.

The configuration of the optical pickup 11 is the same as that described with reference to FIG. 14, and the same components will be described with the same reference numerals.
The tracking error signal amplitude detecting means 35 will be described.

  The tracking error signal amplitude detection unit 35 detects the amplitude from the difference between the maximum value and the minimum value of the tracking error signal output from the tracking error detection unit 33. The tracking error signal output from the tracking error detection means 33 is a track on the disc with respect to the radial direction of the disc in a state where the focus is controlled so that a small spot is focused on an arbitrary layer of the optical disc 6. And a signal corresponding to a relative positional deviation between the small spot and the minute spot.

The tracking error signal amplitude comparison means 36 will be described.
The tracking error signal amplitude value output from the tracking error signal amplitude detection means 35 is compared with the value stored in the threshold value storage means 34, and if the tracking error signal amplitude is larger than the value stored in the threshold value storage means 34. When the tracking error signal amplitude value output from the detection means 35 is larger, an arbitrary value determined in advance is output. Let this arbitrary value be the value a. If the tracking error signal amplitude value output from the tracking error signal amplitude detection means 35 is compared with the value stored in the threshold storage means 34, the tracking error is greater than the value stored in the threshold storage means 34. When the tracking error signal amplitude value output from the signal amplitude detection means 35 is smaller, a value other than the arbitrary value a is output.

  Further, the value output from the tracking error signal amplitude comparing means 36 may be the following value. That is, it may be a difference value between the value output from the tracking error signal amplitude detecting means 35 and the value stored in the threshold value storing means 34.

The threshold storage unit 34 will be described.
The threshold value storage means 34 stores an arbitrary value that is 90% or less and 20% or more of the tracking error signal amplitude value in a state where the minute spot is focused on the target layer and the spherical aberration is corrected. ing. Here, 90% or less is the tracking error signal amplitude value when the minute spot is focused on the target layer and the spherical aberration is corrected, and the minute spot with respect to the target layer. This is because the upper limit value can be discriminated from the state in which the spherical aberration is not corrected. Further, 20% or more is the tracking error signal amplitude value in a state in which the minute spot is focused on the target layer and the spherical aberration is corrected, and the minute spot is smaller than the target layer. This is because the lower limit value can be discriminated from the state where the focus is in focus but the spherical aberration is not corrected.

The layer determination unit 37 will be described.
The layer determination unit 37 determines whether the minute spot is focused on the target layer or whether the minute spot is focused on a layer other than the target by the signal output from the tracking error signal amplitude comparison unit 36. judge. The determination method is as follows. For example, as described in the description of the tracking error signal amplitude comparison unit 36, when the value output from the tracking error signal amplitude comparison unit 36 is the value a, the minute spot is focused on the target layer. If the value output from the tracking error signal amplitude comparison means 36 is other than the value a, it is determined that the minute spot is in focus other than the target layer. Further, when the difference value between the value output from the tracking error signal amplitude detecting means 35 and the value stored in the threshold value storing means 34 is output from the tracking error signal amplitude comparing means 36, the tracking error signal This is determined by the polarity of the value output from the amplitude comparison means 36. That is, when the layer is determined by the following calculation formula, if the output value from the tracking error signal amplitude comparison means 36 is positive, it is determined that the minute spot is in focus on the target layer, and the negative electrode is If so, it is determined that the fine spot is focused on a layer other than the target layer. If the output value from the tracking error signal amplitude comparison means 36 is E01, the value output from the tracking error signal amplitude detection means 35 is ES1, and the value stored in the threshold value storage means 34 is ER1.
E01 = ES1-ER1
Further, when the layer is determined by the following calculation formula, if the output value from the tracking error signal amplitude comparing means 36 becomes a negative electrode, it is determined that the minute spot is focused on the target layer, and the positive electrode is If so, it is determined that the fine spot is focused on a layer other than the target layer.

E01 = ER1-ES1
Based on the determination result, the layer determination unit 37 sends an instruction to the actuator driving unit 38 to focus the minute spot on the target layer if the layer other than the target is in focus. .

Next, the layer determination procedure of this embodiment will be described.
First, the type and number of layers of the optical disc 6 are discriminated by the control means 39. Next, after the layer to be focused on the minute spot is determined, the correction amount information obtained from the aberration correction amount storage means 31 is used to correct the aberration that occurs when focusing on the target layer. Thus, the aberration correction element driving means 26 is controlled by the control means 39 to drive the liquid crystal aberration correction element 4.

  Next, the control means 39 controls the actuator drive means 38 based on the signals obtained from the photodetectors 8 and 9 and the focus error detection means 32, and drives the actuator 7 to make a minute amount on the target layer of the optical disk 6. Performs spot focusing. On the other hand, the tracking error detection means 33 outputs a signal corresponding to the relative shift amount between the track on the optical disc 6 and the minute spot based on the signals output from the photodetectors 8 and 9. The tracking error signal amplitude detection unit 35 calculates the tracking error amplitude from the difference between the maximum value and the minimum value of the signal from the tracking error detection unit 33. The tracking error signal amplitude comparison means 36 compares the calculated tracking error amplitude with the value of the threshold value storage means, and outputs the result. Based on the result of the tracking error signal amplitude comparison unit 36, the layer determination unit 37 generates a signal for determining whether the focus of the minute spot is on the target layer or on a layer other than the target. Output. After determining that the layer of the optical disc 6 is in focus, the control unit 39 determines whether or not the minute spot is focused on the target layer of the optical disc 6 based on the signal from the layer determination unit 37. If it is determined that the fine spot is focused on a layer other than the target of the optical disc 6, the control means 39 drives the actuator 7 to the actuator driving means 38 so as to quickly focus on the target layer. Control is performed so that they are adjusted again. As a result, a stable error signal can be obtained in the servo control performed on this recording layer in a short time, and data can be normally reproduced and recorded on the target layer of the optical disc 6. It becomes like this.

  In the optical disk apparatus according to the present embodiment, it is possible to detect that the focal point is focused on a layer other than the target by using spherical aberration generated when the minute spot is mistakenly focused on the layer other than the target. In addition, there is an effect that the operation of refocusing the minute spot on the target layer can be performed.

  In the present embodiment, the correction amount of spherical aberration stored in the aberration correction amount storage means 31 can be determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control. An average value may be used. When the correction amount of the spherical aberration is determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control, the correction amount is selected and switched according to the type of the disc and the target layer.

  The spherical aberration correction amount stored in the aberration correction amount storage means 31 may be the spherical aberration correction amount of the liquid crystal aberration correction element 4 when the optical disk apparatus is assembled and adjusted using the optical disk 6 having the reference thickness. You may set from the standard value of the base-material thickness of the optical disk 6. FIG.

  In the present embodiment, each time the optical disk device is started, the value stored in the threshold storage unit 34 may be reset by the following method. That is, the value stored in the threshold value storage means 34 is the magnitude of the signal amplitude detected by the tracking error signal amplitude detection means 35 after the actuator 7 is driven by the actuator drive means 38 and a minute spot converges on an arbitrary layer. The learned value may be reset as a threshold for an arbitrary layer. By correcting the threshold in this way, the error in the output from the tracking error signal amplitude comparison means 36 due to the influence of the change in the tracking error signal over time and the temperature change can be minimized, and the judgment by the layer judgment means 37 It is possible to eliminate erroneous results.

  In the present embodiment, each time the optical disk device is started, the value stored in the threshold storage unit 34 may be reset by the following method. In other words, the value stored in the threshold value storage means 34 sets the driving amount of the aberration correction element driving means 26 to an optimum driving amount for the target layer, and drives the actuator 7 by the actuator driving means 38 so as to be set to an arbitrary layer. The magnitude of the signal amplitude detected by the tracking error signal amplitude detecting means 35 after the minute spot has converged and the driving amount of the aberration correcting element driving means 26 are set to an optimum driving amount other than the target layer, and an arbitrary amount An intermediate value between the magnitude of the signal amplitude detected by the tracking error signal amplitude detection means 35 after the minute spot has converged on the layer may be reset as a threshold value for an arbitrary layer. By correcting the threshold in this way, the error in the output from the tracking error signal amplitude comparison means 36 due to the influence of the change in the tracking error signal over time and the temperature change can be minimized, and the judgment by the layer judgment means 37 It is possible to eliminate erroneous results.

(Embodiment 2)
FIG. 2 shows an optical disc apparatus according to Embodiment 2 of the present invention.
Note that the same constituent elements as those in the first embodiment will be described with the same reference numerals.

  The optical disk apparatus according to the present embodiment includes the same optical pickup 11 as in FIG. 14 described in the conventional example, an aberration correction element driving unit 26 that drives the liquid crystal aberration correction element 4 as an aberration correction unit, and at least two or more pluralities. Aberration correction amount storage means 31 for storing the aberration correction amount for each layer of the optical disk 6 composed of a plurality of layers, actuator drive means 38 for driving the objective lens 5, and a signal obtained from the optical pickup 11 are received and converged on the optical disk 6. Focus error detecting means 32 for detecting the convergence state of the minute spot that has been detected, and tracking error detection means for detecting the relative positional deviation between the minute spot converged on the optical disk 6 and the track on the optical disk 6 33, the output signal from the focus error detection means 32, and the tracking error detection means 3 Actuator driving means 38 for driving the objective lens 5 for converging the laser beam on the disc based on the output signal from the tracking signal, and tracking error signal for detecting the level of the tracking error signal based on the output signal from the tracking error detecting means 33 The level detection means 41, the tracking error signal level comparison means 42 for comparing the signal from the tracking error signal level detection means 41 and the threshold value stored in the threshold value storage means 40, and the tracking error signal level comparison means 42 are output. Based on the result, it is determined whether or not the minute spot has converged on the target layer. If the minute spot is focused on a layer other than the target, the minute spot is focused on the target layer. Actuator driving hand to drive the actuator 7 for The type of the optical disc is discriminated based on the layer determination means 37 for giving an instruction to the output signal 38, the output signals from the photodetectors 8 and 9, the signal from the focus error detection means 32, and the signal from the tracking error detection means 33. The laser light source 1 is made to emit light, the actuator driving means 38 is controlled, the aberration correction element driving means 26 is driven to improve the information signal obtained from the optical pickup 11, and the layer determining means 37 In the case where the focus is drawn into a layer other than the target based on the above signal, control means 39 is provided for performing a process of drawing the focus into the target layer again.

The configuration of the optical pickup 11 is the same as that described with reference to FIG. 14, and the same components as those in FIG.
Next, the tracking error signal level detection means 41 will be described.

  A tracking error signal corresponding to the relative positional deviation between the track on the disk and the minute spot with respect to the radial direction of the disk in a state in which the focus of the minute spot is focused on an arbitrary layer of the optical disk 6 Is output from the tracking error detection means 33. The tracking error signal level detection unit 41 detects the maximum value of the tracking error signal output from the tracking error detection unit 33.

Next, the tracking error signal level comparison means 42 will be described.
The tracking error signal level value output from the tracking error signal level detection means 41 is compared with the value stored in the threshold storage means 40, and the tracking error signal level is greater than the value stored in the threshold storage means 40. When the tracking error signal level value output from the detection means 41 is larger, an arbitrary value determined in advance is output. Let this arbitrary value be the value a. If the tracking error signal level value output from the tracking error signal level detection means 41 is compared with the value stored in the threshold storage means 40, the tracking error is greater than the value stored in the threshold storage means 40. When the tracking error signal level value output from the signal level detection means 41 is smaller, a value other than the arbitrary value a is output.

  Further, the value output from the tracking error signal level comparison means 42 may be the following value. That is, it may be a difference value between the value output from the tracking error signal level detection unit 41 and the value stored in the threshold storage unit 40.

Next, the threshold storage means 40 will be described.
The threshold value storage means 40 stores an arbitrary value of 90% or less and 20% or more of the tracking error signal level value in a state where the minute spot is focused on the target layer and the spherical aberration is corrected. ing. Here, 90% or less is the tracking error signal level value when the minute spot is focused on the target layer and the spherical aberration is corrected, and the minute spot with respect to the target layer. This is because the upper limit value can be discriminated from the state in which the spherical aberration is not corrected. Also, 20% or more is the tracking error signal level value in a state where the minute spot is focused on the target layer and the spherical aberration is corrected, and the minute spot is smaller than the target layer. This is because the lower limit value can be discriminated from the state where the focus is in focus but the spherical aberration is not corrected.

Next, the layer determination unit 37 will be described.
The layer determination unit 37 determines whether the minute spot is focused on the target layer or the layer other than the target is focused by the signal output from the tracking error signal level comparison unit 42. judge. The determination method is as follows. For example, as described in the description of the tracking error signal level comparison unit 42, when the value output from the tracking error signal level comparison unit 42 is a value a, the minute spot is focused on the target layer. If the value output from the tracking error signal level comparison means 42 is other than the value a, it is determined that the minute spot is in focus other than the target layer. Further, when the difference value between the value output from the tracking error signal level detection means 41 and the value stored in the threshold storage means 40 is output from the tracking error signal level comparison means 42, the tracking error signal This is determined by the polarity of the value output from the level comparison means 42. That is, when the layer is determined by the following calculation formula, if the output value from the tracking error signal level comparison means 42 is positive, it is determined that the target spot is focused on the minute spot, and the negative electrode is If so, it is determined that the fine spot is focused on a layer other than the target layer. Assuming that the output value from the tracking error signal level comparison means 42 is E02, the value output from the tracking error signal level detection means 41 is ES2, and the value stored in the threshold value storage means 40 is ER2.
E02 = ES2-ER2
In addition, when the layer is determined by the following calculation formula, if the output value from the tracking error signal level comparison means 42 is a negative electrode, it is determined that the target spot is focused on the minute spot, and the positive electrode is If so, it is determined that the fine spot is focused on a layer other than the target layer.

E02 = ER2-ES2
Based on the determination result, the layer determination unit 37 sends an instruction to the actuator driving unit 38 to focus the minute spot on the target layer if the layer other than the target is in focus. .

Next, the layer determination procedure of this embodiment will be described.
First, the type and number of layers of the optical disc 6 are discriminated by the control means 39. Next, after the layer to be focused on the minute spot is determined, the correction amount information obtained from the aberration correction amount storage means 31 is used to correct the aberration that occurs when focusing on the target layer. Thus, the aberration correction element driving means 26 is controlled by the control means 39 to drive the liquid crystal aberration correction element 4. Next, the control means 39 controls the actuator drive means 38 based on the signals obtained from the photodetectors 8 and 9 and the focus error detection means 32, and drives the actuator 7 to make a minute amount on the target layer of the optical disk 6. Performs spot focusing. On the other hand, the tracking error detection means 33 outputs a signal corresponding to the relative shift amount between the track on the optical disc 6 and the minute spot based on the signals output from the photodetectors 8 and 9. The tracking error signal level detection unit 41 calculates a tracking error level from the maximum value of the signal from the tracking error detection unit 33. The tracking error signal level comparison means 42 compares the calculated tracking error level with the value of the threshold value storage means, and outputs the result. Based on the result of the tracking error signal level comparing unit 42, the layer determining unit 37 generates a signal for determining whether the focus of the minute spot is on the target layer or on a layer other than the target. Output. After determining that the layer of the optical disc 6 is in focus, the control unit 39 determines whether or not the minute spot is focused on the target layer of the optical disc 6 based on the signal from the layer determination unit 37. If it is determined that the fine spot is focused on a layer other than the target of the optical disc 6, the control means 39 drives the actuator 7 to the actuator driving means 38 so as to quickly focus on the target layer. Control is performed so that they are adjusted again. As a result, a stable error signal can be obtained in the servo control performed on this recording layer in a short time, and data can be normally reproduced and recorded on the target layer of the optical disc 6. It becomes like this.

  In the optical disk apparatus according to the present embodiment, it is possible to detect that the focal point is focused on the layer other than the target by using the spherical aberration generated when the minute spot is mistakenly focused on the layer other than the target. There is an effect that the operation of refocusing the minute spot on the target layer can be performed.

  In the present embodiment, the correction amount of spherical aberration stored in the aberration correction amount storage means 31 can be determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control. An average value may be used. When the correction amount of the spherical aberration is determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control, the correction amount is selected and switched according to the type of the disc and the target layer.

  The spherical aberration correction amount stored in the aberration correction amount storage means 31 may be the spherical aberration correction amount of the liquid crystal aberration correction element 4 when the optical disk apparatus is assembled and adjusted using the optical disk 6 having the reference thickness. You may set from the standard value of the base-material thickness of the optical disk 6. FIG.

  In the present embodiment, each time the optical disk device is started, the value stored in the threshold storage unit 40 may be reset by the following method. That is, the value stored in the threshold value storage means 40 is the magnitude of the signal level detected by the tracking error signal level detection means 41 after the actuator 7 is driven by the actuator drive means 38 and a minute spot converges on an arbitrary layer. The learned value may be reset as a threshold for an arbitrary layer. By correcting the threshold in this way, the error in the output from the tracking error signal level comparison means 42 due to the change in the tracking error signal with time and the influence of temperature can be minimized. It is possible to eliminate erroneous results.

  In the present embodiment, each time the optical disk device is started, the value stored in the threshold storage unit 40 may be reset by the following method. That is, the value stored in the threshold value storage means 40 is such that the driving amount of the aberration correction element driving means 26 is set to an optimum driving amount for the target layer, and the actuator 7 is driven by the actuator driving means 38 to be set to an arbitrary layer. The magnitude of the signal level detected by the tracking error signal level detection means 41 after the convergence of the minute spot and the driving amount of the aberration correction element driving means 26 are set to an optimum driving amount other than the target layer, and an arbitrary amount is set. An intermediate value between the magnitude of the signal level detected by the tracking error signal level detection means 41 after the minute spot has converged on the layer may be reset as a threshold for an arbitrary layer. By correcting the threshold in this way, the error in the output from the tracking error signal level comparison means 42 due to the change in the tracking error signal with time and the influence of temperature can be minimized. It is possible to eliminate erroneous results.

(Embodiment 3)
FIG. 3 shows an optical disc apparatus according to Embodiment 3 of the present invention.
Note that the same components as those in the above-described second embodiment are described with the same reference numerals.

  The optical disk apparatus according to the present embodiment includes the same optical pickup 11 as in FIG. 14 described in the conventional example, an aberration correction element driving unit 26 that drives the liquid crystal aberration correction element 4 as an aberration correction unit, and at least two or more pluralities. Aberration correction amount storage means 31 for storing the aberration correction amount for each layer of the optical disk 6 composed of a plurality of layers, actuator drive means 38 for driving the objective lens 5, and a signal obtained from the optical pickup 11 are received and converged on the optical disk 6. Focus error detecting means 32 for detecting the convergence state of the minute spot that has been detected, and tracking error detection means for detecting the relative positional deviation between the minute spot converged on the optical disk 6 and the track on the optical disk 6 33, the output signal from the focus error detection means 32, and the tracking error detection means 3 Based on the output signal from the actuator, the actuator driving means 38 for driving the objective lens 5 for converging the laser beam on the disk, and the tracking error signal for detecting the balance of the tracking error signal based on the output signal from the tracking error detecting means 33 The balance detection means 45, the tracking error balance comparison means 46 for comparing the signal from the tracking error signal balance detection means 45 with the threshold value stored in the threshold value storage means 44, and the result output from the tracking error balance comparison means 46 Based on the Actuator drive to drive the actuator 7 The type of the optical disc is determined based on the layer determination means 37 for giving an instruction to the stage 38, the output signals from the photodetectors 8 and 9, the signal from the focus error detection means 32, and the signal from the tracking error detection means 33. The laser light source 1 is emitted, the actuator drive means 38 is controlled, the aberration correction element drive means 26 is driven to improve the information signal obtained from the optical pickup 11, and the layer determination means 37 In the case where the focus is drawn into a layer other than the target based on the signal from, the control means 39 for performing the process of drawing the focus into the target layer again is provided.

The configuration of the optical pickup 11 is the same as that described with reference to FIG. 14, and the same components as those in FIG.
Next, the tracking error signal balance detection unit 45 will be described.

  A tracking error signal corresponding to the relative positional deviation between the track on the disk and the minute spot with respect to the radial direction of the disk in a state in which the focus of the minute spot is focused on an arbitrary layer of the optical disk 6 Is output from the tracking error detection means 33. The tracking error signal balance detection unit 45 detects the balance value of the tracking error signal output from the tracking error detection unit 33.

Next, the tracking error balance comparison means 46 will be described.
The tracking error signal balance value output from the tracking error signal balance detection unit 45 is compared with the value stored in the threshold storage unit 44, and if the tracking error signal balance is greater than the value stored in the threshold storage unit 44, When the tracking error signal balance value output from the detection means 45 is smaller, an arbitrary value determined in advance is output. Let this arbitrary value be the value a. If the tracking error signal balance value output from the tracking error signal balance detection means 45 is compared with the value stored in the threshold storage means 44, the tracking error is greater than the value stored in the threshold storage means 44. When the tracking error signal balance value output from the signal balance detection means 45 is larger, a value other than the arbitrary value a is output.

  Further, the value output from the tracking error balance comparison means 46 may be the following value. That is, it may be a difference value between the value output from the tracking error signal balance detection unit 45 and the value stored in the threshold storage unit 44.

Next, the threshold storage unit 44 will be described.
The threshold storage means 44 stores an arbitrary value that is 90% or less and 20% or more of the tracking error signal balance value in a state where the minute spot is focused on the target layer and the spherical aberration is corrected. ing. Here, 90% or less is the tracking error signal balance value in a state where the minute spot is in focus with respect to the target layer and the spherical aberration is corrected, and the minute spot with respect to the target layer. This is because the upper limit value can be discriminated from the state in which the spherical aberration is not corrected. Further, 20% or more is the tracking error signal balance value in the state where the minute spot is focused on the target layer and the spherical aberration is corrected, and the minute spot is smaller than the target layer. This is because the lower limit value can be discriminated from the state where the focus is in focus but the spherical aberration is not corrected.

Next, the layer determination unit 37 will be described.
The layer determination unit 37 determines whether the minute spot is focused on the target layer or the layer other than the target is focused based on the signal output from the tracking error balance comparison unit 46. To do. The determination method is as follows. For example, as described in the description of the tracking error balance comparison unit 46, when the value output from the tracking error balance comparison unit 46 is the value a, the minute spot is focused on the target layer. If the value output from the tracking error balance comparison means 46 is other than the value a, it is determined that the minute spot is in focus other than the target layer. Further, when the difference value between the value output from the tracking error signal balance detection unit 45 and the value stored in the threshold storage unit 44 is output from the tracking error balance comparison unit 46, the tracking error balance comparison is performed. This is determined by the polarity of the value output from the means 46. That is, when the layer is determined by the following calculation formula, if the output value from the tracking error balance comparison means 46 becomes a negative electrode, it is determined that the target spot is focused on the minute spot, and the positive electrode can not be used. For example, it is determined that the minute spot is focused on a layer other than the target layer. The output value from the tracking error balance comparison means 46 is E03, and the value output from the tracking error signal balance detection means 45 is ES3.
If the value stored in the threshold storage means 44 is ER3,
E03 = ES3-ER3
Also, when the layer is determined by the following calculation formula, if the output value from the tracking error balance comparison means 46 is positive, it is determined that the target spot is in focus on the minute spot and cannot be negative. For example, it is determined that the minute spot is focused on a layer other than the target layer.

E03 = ER3-ES3
Based on the determination result, the layer determination unit 37 sends an instruction to the actuator driving unit 38 to focus the minute spot on the target layer if the layer other than the target is in focus. .

Next, the layer determination procedure of this embodiment will be described.
First, the type and number of layers of the optical disc 6 are discriminated by the control means 39. Next, after the layer to be focused on the minute spot is determined, the correction amount information obtained from the aberration correction amount storage means 31 is used to correct the aberration that occurs when focusing on the target layer. Thus, the aberration correction element driving means 26 is controlled by the control means 39 to drive the liquid crystal aberration correction element 4. Next, the control means 39 controls the actuator drive means 38 based on the signals obtained from the photodetectors 8 and 9 and the focus error detection means 32, and drives the actuator 7 to make a minute amount on the target layer of the optical disk 6. Performs spot focusing. On the other hand, the tracking error detection means 33 outputs a signal corresponding to the relative shift amount between the track on the optical disc 6 and the minute spot based on the signals output from the photodetectors 8 and 9. The tracking error signal balance detection unit 45 calculates a tracking error balance value from the maximum value and the minimum value of the signal from the tracking error detection unit 33. The tracking error balance comparison means 46 compares the calculated tracking error balance value with the value of the threshold value storage means, and outputs the result. Based on the result of the tracking error balance comparison unit 46, the layer determination unit 37 outputs a signal for determining whether the focus of the minute spot is on the target layer or on a layer other than the target. To do. After determining that the layer of the optical disc 6 is in focus, the control unit 39 determines whether or not the minute spot is focused on the target layer of the optical disc 6 based on the signal from the layer determination unit 37. If it is determined that the fine spot is focused on a layer other than the target of the optical disc 6, the control means 39 drives the actuator 7 to the actuator driving means 38 so as to quickly focus on the target layer. Control is performed so that they are adjusted again. As a result, a stable error signal can be obtained in the servo control performed on this recording layer in a short time, and data can be normally reproduced and recorded on the target layer of the optical disc 6. It becomes like this.

  In the optical disk apparatus according to the present embodiment, it is possible to detect that the focal point is focused on the layer other than the target by using the spherical aberration generated when the minute spot is mistakenly focused on the layer other than the target. There is an effect that the operation of refocusing the minute spot on the target layer can be performed.

  In the present embodiment, the correction amount of spherical aberration stored in the aberration correction amount storage means 31 can be determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control. An average value may be used. When the correction amount of the spherical aberration is determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control, the correction amount is selected and switched according to the type of the disc and the target layer.

  The spherical aberration correction amount stored in the aberration correction amount storage means 31 may be the spherical aberration correction amount of the liquid crystal aberration correction element 4 when the optical disk apparatus is assembled and adjusted using the optical disk 6 having the reference thickness. You may set from the standard value of the base-material thickness of the optical disk 6. FIG.

  In the present embodiment, every time the optical disk device is started, the value stored in the threshold storage unit 44 may be reset by the following method. That is, the value stored in the threshold value storage means 44 is the magnitude of the signal level detected by the tracking error signal balance detection means 45 after the actuator 7 is driven by the actuator drive means 38 and a minute spot converges on an arbitrary layer. The learned value may be reset as a threshold value for an arbitrary layer. By correcting the threshold in this way, the error in the output from the tracking error balance comparison means 46 due to the influence of the tracking error signal over time and the temperature change can be minimized. It is possible to eliminate the error.

  In the present embodiment, every time the optical disk device is started, the value stored in the threshold storage unit 44 may be reset by the following method. That is, the value stored in the threshold value storage means 44 is such that the driving amount of the aberration correction element driving means 26 is set to an optimum driving amount for the target layer, and the actuator driving means 38 drives the actuator 7 so that it can be set to any layer. The magnitude of the signal level detected by the tracking error signal balance detection means 45 after the fine spot has converged and the drive amount of the aberration correction element drive means 26 are set to an optimum drive amount other than the target layer, and an arbitrary amount An intermediate value between the level of the signal level detected by the tracking error signal balance detection unit 45 after the minute spot has converged on the layer may be reset as a threshold value for an arbitrary layer. By correcting the threshold in this way, the error in the output from the tracking error balance comparison means 46 due to the influence of the tracking error signal over time and the temperature change can be minimized. It is possible to eliminate the error.

(Embodiment 4)
FIG. 4 shows an optical disc apparatus according to Embodiment 4 of the present invention.
In addition, the same code | symbol is attached | subjected and demonstrated about the same component as Embodiment 3 mentioned above.

  The optical disk apparatus according to the present embodiment includes the same optical pickup 11 as in FIG. 14 described in the conventional example, an aberration correction element driving unit 26 that drives the liquid crystal aberration correction element 4 as an aberration correction unit, and at least two or more pluralities. Aberration correction amount storage means 31 for storing the aberration correction amount for each layer of the optical disk 6 composed of a plurality of layers, actuator drive means 38 for driving the objective lens 5, and a signal obtained from the optical pickup 11 are received and converged on the optical disk 6. Focus error detecting means 32 for detecting the convergence state of the minute spot that has been detected, and tracking error detection means for detecting the relative positional deviation between the minute spot converged on the optical disk 6 and the track on the optical disk 6 33, the output signal from the focus error detection means 32, and the tracking error detection means 3 Based on the output signal from, the actuator drive means 38 for driving the objective lens 5 for converging the laser beam on the disk, and the deviation between the amplitude of the tracking error signal 52 output from the tracking error detection means 33 and the target amplitude are detected. Based on the output from the tracking error signal AGC detecting means 49 and the tracking error signal AGC detecting means 49, the tracking error signal amplifying means 51 for amplifying the tracking error signal 53 inputted to the control means 39 so as to keep the amplitude constant. The tracking error signal AGC value comparing means 50 for comparing the signal from the tracking error signal AGC detecting means 49 with the threshold value stored in the threshold value storing means 48, and the result output from the tracking error signal AGC value comparing means 50 Based on the minute spot If the minute spot is focused on a layer other than the target, the actuator 7 is driven so as to focus the minute spot on the target layer. The type of the optical disc is determined based on the layer determination means 37 that gives an instruction to the actuator driving means 38, the output signals from the photodetectors 8 and 9, the signal from the focus error detection means 32, and the signal from the tracking error detection means 33. Discriminating, causing the laser light source 1 to emit light, controlling the actuator driving means 38, driving the aberration correction element driving means 26, improving the information signal obtained from the optical pickup 11, and further determining the layer If the focus is drawn into a layer other than the target based on the signal from the means 37, the focus is drawn back into the target layer. And system control means 39 for performing processing.

The configuration of the optical pickup 11 is the same as that described with reference to FIG. 14, and the same components as those in FIG.
Next, the tracking error signal AGC detection means 49 will be described.

  A tracking error signal corresponding to the relative positional deviation between the track on the disk and the minute spot with respect to the radial direction of the disk in a state in which the focus of the minute spot is focused on an arbitrary layer of the optical disk 6 Is output from the tracking error detection means 33. The tracking error signal AGC detection means 49 detects the value of the ratio between the amplitude of the tracking error signal 52 and the amplitude target value output from the tracking error detection means 33.

Next, the tracking error signal AGC value comparison means 50 will be described.
The tracking error signal AGC value output from the tracking error signal AGC detection means 49 is compared with the value stored in the threshold storage means 48, and if the tracking error signal AGC is greater than the value stored in the threshold storage means 48. When the tracking error signal AGC value output from the detecting means 49 is smaller, an arbitrary value determined in advance is output. Let this arbitrary value be the value a. If the tracking error signal AGC value output from the tracking error signal AGC detection means 49 is compared with the value stored in the threshold storage means 48, the tracking error is greater than the value stored in the threshold storage means 48. When the tracking error signal AGC value output from the signal AGC detection means 49 is larger, a value other than the arbitrary value a is output.

  Further, the value output from the tracking error signal AGC value comparison means 50 may be the following value. That is, it may be a difference value between the value output from the tracking error signal AGC detection means 49 and the value stored in the threshold value storage means 48.

Next, the threshold storage means 48 will be described.
The threshold value storage means 48 stores an arbitrary value not less than 90% and not less than 20% of the tracking error signal AGC value when the minute spot is focused on the target layer and the spherical aberration is corrected. ing. Here, 90% or less is the tracking error signal AGC value when the fine spot is focused on the target layer and the spherical aberration is corrected, and the fine spot with respect to the target layer. This is because the upper limit value can be discriminated from the state in which the spherical aberration is not corrected. Further, 20% or more is because the tracking error signal AGC value when the minute spot is focused on the target layer and the spherical aberration is corrected, and the minute spot is smaller than the target layer. This is because the lower limit value can be discriminated from the state in which the lens is in focus but the spherical aberration is not corrected.

Next, the layer determination unit 37 will be described.
In the layer determining unit 37, whether the minute spot is focused on the target layer or whether the minute spot is focused on a layer other than the target according to the signal output from the tracking error signal AGC value comparing unit 50. Determine. The determination method is as follows. For example, as described in the description of the tracking error signal AGC value comparison unit 50, when the value output from the tracking error signal AGC value comparison unit 50 is the value a, the focus of the minute spot on the target layer is If the value output from the tracking error signal AGC value comparison means 50 is other than the value a, it is determined that the minute spot is in focus other than the target layer. If the difference between the value output from the tracking error signal AGC detection means 49 and the value stored in the threshold storage means 48 is output from the tracking error signal AGC value comparison means 50, the tracking error This is determined by the polarity of the value output from the signal AGC value comparison means 50. That is, when the layer is determined by the following calculation formula, if the output value from the tracking error signal AGC value comparing means 50 is negative, it is determined that the minute spot is focused on the target layer, and the positive electrode If so, it is determined that the minute spot is focused on a layer other than the target layer. If the output value from the tracking error signal AGC value comparison means 50 is E04, the value output from the tracking error signal AGC detection means 49 is ES4, and the value stored in the threshold value storage means 48 is ES4,
E04 = ES4-ER4
Further, when the layer is determined by the following calculation formula, if the output value from the tracking error signal AGC value comparison means 50 is positive, it is determined that the minute spot is focused on the target layer, and the negative electrode If so, it is determined that the minute spot is focused on a layer other than the target layer.

E04 = ER4-ES4
Based on the determination result, the layer determination unit 37 sends an instruction to the actuator driving unit 38 to focus the minute spot on the target layer if the layer other than the target is in focus. .

Next, the layer determination procedure of this embodiment will be described.
First, the type and number of layers of the optical disc 6 are discriminated by the control means 39. Next, after the layer to be focused on the minute spot is determined, the correction amount information obtained from the aberration correction amount storage means 31 is used to correct the aberration that occurs when focusing on the target layer. Thus, the aberration correction element driving means 26 is controlled by the control means 39 to drive the liquid crystal aberration correction element 4. Next, the control means 39 controls the actuator drive means 38 based on the signals obtained from the photodetectors 8 and 9 and the focus error detection means 32, and drives the actuator 7 to make a minute amount on the target layer of the optical disk 6. Performs spot focusing. On the other hand, the tracking error detection means 33 outputs a signal corresponding to the relative shift amount between the track on the optical disc 6 and the minute spot based on the signals output from the photodetectors 8 and 9. The tracking error signal AGC detection means 49 calculates the AGC value of the tracking error from the difference between the maximum value and the minimum value of the signal from the tracking error detection means 33. The tracking error signal AGC value comparison means 50 compares the calculated tracking error AGC value with the value of the threshold value storage means, and outputs the result. Based on the result of the tracking error signal AGC value comparing means 50, the layer determining means 37 is a signal for determining whether the focus of the minute spot is on the target layer or on a layer other than the target. Is output. After determining that the layer of the optical disc 6 is in focus, the control unit 39 determines whether or not the minute spot is focused on the target layer of the optical disc 6 based on the signal from the layer determination unit 37. If it is determined that the fine spot is focused on a layer other than the target of the optical disc 6, the control means 39 drives the actuator 7 to the actuator driving means 38 so as to quickly focus on the target layer. Control is performed so that they are adjusted again. As a result, a stable error signal can be obtained in the servo control performed on this recording layer in a short time, and data can be normally reproduced and recorded on the target layer of the optical disc 6. It becomes like this.

  In the optical disk apparatus according to the present embodiment, it is possible to detect that the focal point is focused on the layer other than the target by using the spherical aberration generated when the minute spot is mistakenly focused on the layer other than the target. There is an effect that the operation of refocusing the minute spot on the target layer can be performed.

  In the present embodiment, the correction amount of spherical aberration stored in the aberration correction amount storage means 31 can be determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control. An average value may be used. When the correction amount of the spherical aberration is determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control, the correction amount is selected and switched according to the type of the disc and the target layer.

  The spherical aberration correction amount stored in the aberration correction amount storage means 31 may be the spherical aberration correction amount of the liquid crystal aberration correction element 4 when the optical disk apparatus is assembled and adjusted using the optical disk 6 having the reference thickness. You may set from the standard value of the base-material thickness of the optical disk 6. FIG.

  In the present embodiment, each time the optical disk device is started, the value stored in the threshold storage unit 48 may be reset by the following method. That is, the value stored in the threshold value storage means 48 is the magnitude of the signal level detected by the tracking error signal AGC detection means 49 after the actuator 7 is driven by the actuator drive means 38 and a minute spot converges on an arbitrary layer. The learned value may be reset as a threshold for an arbitrary layer. By correcting the threshold value by such a method, an error in output from the tracking error signal AGC value comparing means 50 due to the influence of the change in the tracking error signal with time and the temperature change can be minimized, and the layer determining means 37 It is possible to eliminate an error in the determination result.

  In the present embodiment, each time the optical disk device is started, the value stored in the threshold storage unit 48 may be reset by the following method. In other words, the value stored in the threshold value storage means 48 sets the driving amount of the aberration correction element driving means 26 to an optimum driving amount for the target layer, and drives the actuator 7 by the actuator driving means 38 so as to be set to an arbitrary layer. The magnitude of the signal level detected by the tracking error signal AGC detection means 49 after the minute spot has converged and the drive amount of the aberration correction element drive means 26 are set to an optimum drive amount other than the target layer, and an arbitrary An intermediate value between the level of the signal level detected by the tracking error signal AGC detection means 49 after the minute spot has converged on the layer may be reset as a threshold value for an arbitrary layer. By correcting the threshold value by such a method, an error in output from the tracking error signal AGC value comparing means 50 due to the influence of the change in the tracking error signal with time and the temperature change can be minimized, and the layer determining means 37 It is possible to eliminate an error in the determination result.

(Embodiment 5)
FIG. 5 shows an optical disc apparatus according to Embodiment 1 of the present invention.
In addition, the same code | symbol is attached | subjected and demonstrated about the same component as Embodiment 4 mentioned above.

  The optical disk apparatus according to the present embodiment includes the same optical pickup 11 as in FIG. 14 described in the conventional example, an aberration correction element driving unit 26 that drives the liquid crystal aberration correction element 4 as an aberration correction unit, and at least two or more pluralities. Aberration correction amount storage means 31 for storing the aberration correction amount for each layer of the optical disk 6 composed of a plurality of layers, actuator drive means 38 for driving the objective lens 5, and a signal obtained from the optical pickup 11 are received and converged on the optical disk 6. A focus error detecting means 32 for detecting the convergence state of the minute spot, an addition signal generating means 60 for generating a sum signal of the outputs of the photodetectors 8 and 9, an output signal from the focus error detecting means 32, and addition Based on the output signal from the signal generating means 60, an actuator for driving the objective lens 5 for converging the laser on the disk. Data drive means 38, addition signal level detection means 62 for detecting the level of the addition signal based on the output signal from addition signal generation means 60, and signal from addition signal level detection means 62 and threshold value storage means 61. Based on the result output from the added signal level comparing means 63 and the added signal level comparing means 63, it is determined whether or not the minute spot has converged on the target layer. When the minute spot is in focus on the other layer, the layer determining means 37 for giving an instruction to the actuator driving means 38 to drive the actuator 7 in order to focus the minute spot on the target layer, and the light The type of the optical disk based on the output signals from the detectors 8 and 9, the signal from the focus error detection means 32, and the signal from the addition signal generation means 60 Discriminating, causing the laser light source 1 to emit light, controlling the actuator driving means 38, driving the aberration correction element driving means 26, improving the information signal obtained from the optical pickup 11, and further determining the layer When the focus is drawn into a layer other than the target based on the signal from the means 37, a control means 39 for performing a process of drawing the focus into the target layer again is provided.

The configuration of the optical pickup 11 is the same as that described with reference to FIG. 14, and the same components as those in FIG.
Next, the addition signal level detection means 62 will be described.

  The light detectors 8 and 9 receive the light reflected from the disk in a state in which the focus of the minute spot is focused on an arbitrary layer of the optical disk 6. Signals received and photoelectrically converted by the photodetectors 8 and 9 are output from the photodetectors 8 and 9. The sum of the signals output from the photodetectors 8 and 9 is output from the added signal generating means 60. The addition signal level detection unit 62 detects the maximum value of the addition signal output from the addition signal generation unit 60.

Next, the addition signal level comparison means 63 will be described.
The addition signal level value output from the addition signal level detection means 62 is compared with the value stored in the threshold value storage means 61, and if the value stored in the threshold value storage means 61 is greater than the value stored in the threshold value storage means 61. When the added signal level value output from is larger, an arbitrary value determined in advance is output. Let this arbitrary value be the value a. If the added signal level value output from the added signal level detection means 62 is compared with the value stored in the threshold value storage means 61, the added signal level detection is greater than the value stored in the threshold value storage means 61. When the added signal level value output from the means 62 is smaller, a value other than the arbitrary value a is output.

  Further, the value output from the addition signal level comparison unit 63 may be the following value. That is, it may be a difference value between the value output from the addition signal level detection unit 62 and the value stored in the threshold storage unit 61.

Next, the threshold storage unit 61 will be described.
The threshold value storage means 61 stores an arbitrary value of 90% or less and 20% or more of the added signal level value when the minute spot is focused on the target layer and the spherical aberration is corrected. Yes. Here, 90% or less means that the minute spot is in focus with respect to the target layer and the spherical signal is corrected, and the added signal level value and the minute spot with respect to the target layer. This is because the upper limit value can be discriminated from the state where the focus is in focus but the spherical aberration is not corrected. Further, 20% or more is the added signal level value when the minute spot is focused on the target layer and the spherical aberration is corrected, and the focus of the minute spot on the target layer. This is because the lower limit value can be discriminated from the state in which the spherical aberration is not corrected.

Next, the layer determination unit 37 will be described.
The layer determination unit 37 determines whether the minute spot is focused on the target layer or the layer other than the target is focused based on the signal output from the addition signal level comparison unit 63. To do. The determination method is as follows. For example, as described in the description of the addition signal level comparison unit 63, when the value output from the addition signal level comparison unit 63 is a value a, the minute spot is focused on the target layer. If the value output from the addition signal level comparison means 63 is other than the value a, it is determined that the minute spot is in focus other than the target layer. Further, when the difference value between the value output from the addition signal level detection means 62 and the value stored in the threshold value storage means 61 is output from the addition signal level comparison means 63, the addition signal level comparison means This is determined by the polarity of the value output from 63. That is, when the layer is determined by the following calculation formula, if the output value from the addition signal level comparison means 63 is positive, it is determined that the target spot is focused on the minute spot and cannot be negative. For example, it is determined that the minute spot is focused on a layer other than the target layer.
If the output value from the addition signal level comparison means 63 is E05, the value output from the addition signal level detection means 62 is ES5, and the value stored in the threshold value storage means 61 is ER5,
E05 = ES5-ER5
In addition, when the layer is determined by the following calculation formula, if the output value from the addition signal level comparison unit 63 is a negative electrode, it is determined that the target spot is focused on the minute spot, and the positive electrode cannot be used. For example, it is determined that the minute spot is focused on a layer other than the target layer.

E05 = ER5-ES5
Based on the determination result, the layer determination unit 37 sends an instruction to the actuator driving unit 38 to focus the minute spot on the target layer if the layer other than the target is in focus. .

Next, the layer determination procedure of this embodiment will be described.
First, the type and number of layers of the optical disc 6 are discriminated by the control means 39. Next, after the layer to be focused on the minute spot is determined, the correction amount information obtained from the aberration correction amount storage means 31 is used to correct the aberration that occurs when focusing on the target layer. Thus, the aberration correction element driving means 26 is controlled by the control means 39 to drive the liquid crystal aberration correction element 4. Next, the control means 39 controls the actuator drive means 38 based on the signals obtained from the photodetectors 8 and 9 and the focus error detection means 32, and drives the actuator 7 to make a minute amount on the target layer of the optical disk 6. Performs spot focusing. On the other hand, the addition signal generating means 60 outputs a signal corresponding to the total light reflected from the optical disk 6 and received by the photodetectors 8 and 9 based on the signals output from the photodetectors 8 and 9. The addition signal level detection unit 62 calculates the level of the addition signal from the maximum value of the signal from the addition signal generation unit 60. The added signal level comparing unit 63 compares the calculated level of the added signal with the value of the threshold storage unit, and outputs the result. The layer determination unit 37 outputs a signal for determining whether the focus of the minute spot is on the target layer or on a layer other than the target based on the result of the addition signal level comparison unit 63. To do. After determining that the layer of the optical disc 6 is in focus, the control unit 39 determines whether or not the minute spot is focused on the target layer of the optical disc 6 based on the signal from the layer determination unit 37. If it is determined that the fine spot is focused on a layer other than the target of the optical disc 6, the control means 39 drives the actuator 7 to the actuator driving means 38 so as to quickly focus on the target layer. Control is performed so that they are adjusted again. As a result, a stable error signal can be obtained in the servo control performed on this recording layer in a short time, and data can be normally reproduced and recorded on the target layer of the optical disc 6. It becomes like this.

  In the optical disk apparatus according to the present embodiment, it is possible to detect that the focal point is focused on the layer other than the target by using the spherical aberration generated when the minute spot is mistakenly focused on the layer other than the target. There is an effect that the operation of refocusing the minute spot on the target layer can be performed.

  In the present embodiment, the correction amount of spherical aberration stored in the aberration correction amount storage means 31 can be determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control. An average value may be used. When the correction amount of the spherical aberration is determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control, the correction amount is selected and switched according to the type of the disc and the target layer.

  The spherical aberration correction amount stored in the aberration correction amount storage means 31 may be the spherical aberration correction amount of the liquid crystal aberration correction element 4 when the optical disk apparatus is assembled and adjusted using the optical disk 6 having the reference thickness. You may set from the standard value of the base-material thickness of the optical disk 6. FIG.

  In the present embodiment, each time the optical disk device is started, the value stored in the threshold storage unit 61 may be reset by the following method. That is, the value stored in the threshold value storage means 61 is the magnitude of the signal level detected by the addition signal level detection means 62 after the actuator 7 is driven by the actuator drive means 38 and the minute spot converges on an arbitrary layer. The value learned from the above may be reset as a threshold for an arbitrary layer. By correcting the threshold value by such a method, an error in the output from the added signal level comparing unit 63 due to the influence of a change in the added signal with time or a temperature change can be minimized, and the result of the determination by the layer determining unit 37 can be reduced. It is possible to eliminate errors.

  In the present embodiment, each time the optical disk device is started, the value stored in the threshold storage unit 61 may be reset by the following method. In other words, the value stored in the threshold value storage means 61 is such that the driving amount of the aberration correction element driving means 26 is the optimum driving amount for the target layer, and the actuator driving means 38 drives the actuator 7 so that it can be set to any layer. The magnitude of the signal level detected by the addition signal level detection means 62 after the convergence of the minute spot and the drive amount of the aberration correction element drive means 26 are set to an optimum drive amount other than the target layer, and an arbitrary layer Alternatively, an intermediate value between the magnitude of the signal level detected by the added signal level detection unit 62 after the minute spot has converged may be reset as a threshold for an arbitrary layer. By correcting the threshold value by such a method, an error in the output from the added signal level comparing unit 63 due to the influence of a change in the added signal with time or a temperature change can be minimized, and the result of the determination by the layer determining unit 37 can be reduced. It is possible to eliminate errors.

(Embodiment 6)
FIG. 6 shows an optical disc apparatus according to Embodiment 6 of the present invention.
Note that the same components as those in the above-described fifth embodiment will be described with the same reference numerals.

  The optical disk apparatus according to the present embodiment includes the same optical pickup 11 as in FIG. 14 described in the conventional example, an aberration correction element driving unit 26 that drives the liquid crystal aberration correction element 4 as an aberration correction unit, and at least two or more pluralities. Aberration correction amount storage means 31 for storing the aberration correction amount for each layer of the optical disk 6 composed of a plurality of layers, actuator drive means 38 for driving the objective lens 5, and a signal obtained from the optical pickup 11 are received and converged on the optical disk 6. Focus error detection means 32 for detecting the convergence state of the minute spot that has been added, and addition signal generation means for detecting the relative positional deviation between the minute spot converged on the optical disk 6 and the track on the optical disk 6 60 and the output signal from the focus error detection means 32 and the output signal from the addition signal generation means 60. Actuator driving means 38 for driving the objective lens 5 for converging the laser beam on the disk, addition signal AGC detection means 67 for detecting the difference between the level of the addition signal 64 output from the addition signal generation means 60 and the target level, Based on the output from the addition signal AGC detection means 67, the addition signal amplification means 68 for amplifying the amplitude of the addition signal 65 input to the control means 39 to keep constant, and the signal from the addition signal AGC detection means 67 Based on the result output from the addition signal AGC value comparison means 69 that compares the threshold value stored in the threshold value storage means 66 and the addition signal AGC value comparison means 69, is the minute spot converged on the target layer? To determine if the microspot is in focus on a layer other than the target to focus the microspot on the target layer The layer determining means 37 for giving an instruction to the actuator driving means 38 to drive the actuator 7, the output signals from the photodetectors 8 and 9, the signal from the focus error detecting means 32, and the addition signal generating means 60 Based on the signal, the type of the optical disc is discriminated, the laser light source 1 is made to emit light, the actuator driving means 38 is controlled, the aberration correction element driving means 26 is driven, and the information signal obtained from the optical pickup 11 is obtained. And a control means 39 for performing a process of drawing the focus again to the target layer when the focus is drawn to a layer other than the target based on the signal from the layer determination means 37. .

The configuration of the optical pickup 11 is the same as that described with reference to FIG. 14, and the same components as those in FIG.
Next, the addition signal AGC detection means 67 will be described.

  The light detectors 8 and 9 receive the light reflected from the disk in a state in which the focus of the minute spot is focused on an arbitrary layer of the optical disk 6. Signals received and photoelectrically converted by the photodetectors 8 and 9 are output from the photodetectors 8 and 9. The sum of the signals output from the photodetectors 8 and 9 is output from the added signal generating means 60. The addition signal AGC detection unit 67 detects the value of the ratio between the amplitude of the addition signal 64 and the amplitude target value output from the addition signal generation unit 60.

Next, the addition signal AGC value comparison means 69 will be described.
The sum signal AGC value output from the sum signal AGC detection means 67 is compared with the value stored in the threshold value storage means 66, and if the sum signal AGC detection means 67 is greater than the value stored in the threshold value storage means 66. When the addition signal AGC value output from is smaller, an arbitrary value determined in advance is output. Let this arbitrary value be the value a. If the addition signal AGC value output from the addition signal AGC detection means 67 is compared with the value stored in the threshold value storage means 66, the addition signal AGC is detected more than the value stored in the threshold value storage means 66. When the addition signal AGC value output from the means 67 is larger, a value other than the arbitrary value a is output.

  Further, the value output from the addition signal AGC value comparison means 69 may be the following value. That is, it may be a difference value between the value output from the addition signal AGC detection unit 67 and the value stored in the threshold storage unit 66.

Next, the threshold storage unit 66 will be described.
The threshold value storage means 66 stores an arbitrary value not less than 90% and not less than 20% of the added signal AGC value in a state where the minute spot is focused on the target layer and the spherical aberration is corrected. Yes. Here, 90% or less is the value of the added signal AGC when the minute spot is focused on the target layer and the spherical aberration is corrected, and the minute spot is smaller than the target layer. This is because the upper limit value can be discriminated from the state where the focus is in focus but the spherical aberration is not corrected. Further, 20% or more is the sum signal AGC value when the minute spot is focused on the target layer and the spherical aberration is corrected, and the focal point of the minute spot with respect to the target layer. This is because the lower limit value can be discriminated from the state in which the spherical aberration is not corrected.

Next, the layer determination unit 37 will be described.
In the layer determination unit 37, whether the minute spot is focused on the target layer or the layer other than the target is focused by the signal output from the addition signal AGC value comparison unit 69. judge. The determination method is as follows. For example, as described in the description of the addition signal AGC value comparison unit 69, when the value output from the addition signal AGC value comparison unit 69 is the value a, the minute spot is focused on the target layer. If the value output from the addition signal AGC value comparison means 69 is other than the value a, it is determined that the minute spot is in focus other than the target layer. Further, when the difference value between the value output from the addition signal AGC detection means 67 and the value stored in the threshold value storage means 66 is output from the addition signal AGC value comparison means 69, the addition signal AGC value This is determined by the polarity of the value output from the comparison means 69. In other words, when the layer is determined by the following calculation formula, if the output value from the addition signal AGC value comparison means 69 becomes a negative electrode, it is determined that the minute spot is in focus on the target layer. If so, it is determined that the fine spot is focused on a layer other than the target layer. If the output value from the addition signal AGC value comparison means 69 is E06, the value output from the addition signal AGC detection means 67 is ES6, and the value stored in the threshold value storage means 66 is ER6,
E06 = ES6-ER6
In addition, when the layer is determined by the following calculation formula, if the output value from the addition signal AGC value comparison means 69 is the positive electrode, it is determined that the minute spot is focused on the target layer, and the negative electrode is If so, it is determined that the fine spot is focused on a layer other than the target layer.

E06 = ER6-ES6
Based on the determination result, the layer determination unit 37 sends an instruction to the actuator driving unit 38 to focus the minute spot on the target layer if the layer other than the target is in focus. .

Next, the layer determination procedure of this embodiment will be described.
First, the type and number of layers of the optical disc 6 are discriminated by the control means 39. Next, after the layer to be focused on the minute spot is determined, the correction amount information obtained from the aberration correction amount storage means 31 is used to correct the aberration that occurs when focusing on the target layer. Thus, the aberration correction element driving means 26 is controlled by the control means 39 to drive the liquid crystal aberration correction element 4. Next, the control means 39 controls the actuator drive means 38 based on the signals obtained from the photodetectors 8 and 9 and the focus error detection means 32, and drives the actuator 7 to make a minute amount on the target layer of the optical disk 6. Performs spot focusing. On the other hand, the addition signal generating means 60 outputs a signal corresponding to the total light reflected from the optical disk 6 and received by the photodetectors 8 and 9 based on the signals output from the photodetectors 8 and 9. The addition signal AGC detection unit 67 calculates the AGC value of the addition signal from the maximum value of the signal from the addition signal generation unit 60. The addition signal AGC value comparison means 69 compares the calculated AGC value of the addition signal with the value of the threshold value storage means, and outputs the result. Based on the result of the addition signal AGC value comparison unit 69, the layer determination unit 37 generates a signal for determining whether the focus of the minute spot is on the target layer or on a layer other than the target. Output. After determining that the layer of the optical disc 6 is in focus, the control unit 39 determines whether or not the minute spot is focused on the target layer of the optical disc 6 based on the signal from the layer determination unit 37. If it is determined that the fine spot is focused on a layer other than the target of the optical disc 6, the control means 39 drives the actuator 7 to the actuator driving means 38 so as to quickly focus on the target layer. Control is performed so that they are adjusted again. As a result, a stable error signal can be obtained in the servo control performed on this recording layer in a short time, and data can be normally reproduced and recorded on the target layer of the optical disc 6. It becomes like this.

  In the optical disk apparatus according to the present embodiment, it is possible to detect that the focal point is focused on the layer other than the target by using the spherical aberration generated when the minute spot is mistakenly focused on the layer other than the target. There is an effect that the operation of refocusing the minute spot on the target layer can be performed.

  In the present embodiment, the correction amount of spherical aberration stored in the aberration correction amount storage means 31 can be determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control. An average value may be used. When the correction amount of the spherical aberration is determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control, the correction amount is selected and switched according to the type of the disc and the target layer.

  The spherical aberration correction amount stored in the aberration correction amount storage means 31 may be the spherical aberration correction amount of the liquid crystal aberration correction element 4 when the optical disk apparatus is assembled and adjusted using the optical disk 6 having the reference thickness. You may set from the standard value of the base-material thickness of the optical disk 6. FIG.

  In the present embodiment, each time the optical disk device is started, the value stored in the threshold storage unit 66 may be reset by the following method. That is, the value stored in the threshold value storage means 66 is the magnitude of the signal level detected by the addition signal AGC detection means 67 after the actuator 7 is driven by the actuator drive means 38 and a minute spot converges on an arbitrary layer. The value learned from the above may be reset as a threshold for an arbitrary layer. By correcting the threshold value by such a method, an error in the output from the added signal AGC value comparing means 69 due to the influence of the change of the added signal over time and the temperature change can be minimized, and the determination result by the layer determining means 37 It is possible to eliminate the error.

  In the present embodiment, each time the optical disk device is started, the value stored in the threshold storage unit 66 may be reset by the following method. That is, the value stored in the threshold value storage means 66 is such that the driving amount of the aberration correction element driving means 26 is set to an optimum driving amount for the target layer, and the actuator 7 is driven by the actuator driving means 38 and is set to an arbitrary layer. The magnitude of the signal level detected by the addition signal AGC detection means 67 after the minute spot has converged and the drive amount of the aberration correction element drive means 26 are set to an optimum drive amount other than the target layer, and an arbitrary layer Alternatively, an intermediate value between the magnitude of the signal level detected by the addition signal AGC detection means 67 after the minute spot has converged may be reset as a threshold for an arbitrary layer. By correcting the threshold value by such a method, an error in the output from the added signal AGC value comparing means 69 due to the influence of the change of the added signal over time and the temperature change can be minimized, and the determination result by the layer determining means 37 It is possible to eliminate the error.

(Embodiment 7)
FIG. 7 shows an optical disc apparatus according to Embodiment 7 of the present invention.
Note that the same components as those in the above-described sixth embodiment will be described with the same reference numerals.

  The optical disk apparatus according to the present embodiment includes the same optical pickup 11 as in FIG. 14 described in the conventional example, an aberration correction element driving unit 26 that drives the liquid crystal aberration correction element 4 as an aberration correction unit, and at least two or more pluralities. Aberration correction amount storage means 31 for storing the aberration correction amount for each layer of the optical disk 6 composed of a plurality of layers, actuator drive means 38 for driving the objective lens 5, and a signal obtained from the optical pickup 11 are received and converged on the optical disk 6. From the focus error detection means 32 for detecting the convergence state of the minute spot, the RF signal generation means 70 for generating a signal for reproducing the data recorded on the optical disc 6, and the focus error detection means 32 Based on the output signal and the output signal from the RF signal generating means 70, the laser beam is focused on the disk. Actuator driving means 38 for driving the lens 5, RF signal amplitude detecting means 72 for detecting the amplitude of the reproduction signal based on the output signal from the RF signal generating means 70, and a signal and threshold value storage from the RF signal amplitude detecting means 72 Based on the RF signal amplitude comparing means 73 that compares the threshold value stored in the means 71 and the result output from the RF signal amplitude comparing means 73, it is determined whether or not the minute spot has converged on the target layer. If the minute spot is focused on a layer other than the target, a layer determination unit that gives an instruction to the actuator driving unit 38 to drive the actuator 7 to focus the minute spot on the target layer 37, the output signals from the photodetectors 8 and 9, the signal from the focus error detection means 32, and the signal from the RF signal generation means 70. Discriminating the type of optical disk, causing the laser light source 1 to emit light, controlling the actuator driving means 38, driving the aberration correction element driving means 26, and improving the information signal obtained from the optical pickup 11, Furthermore, when the focus is drawn into a layer other than the target based on the signal from the layer determination unit 37, a control unit 39 that performs a process of drawing the focus into the target layer again is provided.

The configuration of the optical pickup 11 is the same as that described with reference to FIG. 14, and the same components as those in FIG.
Next, the RF signal amplitude detection means 72 will be described.

  In a state in which the fine spot is focused on an arbitrary layer of the optical disc 6, light is irradiated to the pits formed on the recording surface of the disc, and the light reflected from the optical disc is detected by the photodetectors 8, 9 is incident. Light incident on the photodetectors 8 and 9 is photoelectrically converted and output. The signals output from the photodetectors 8 and 9 are RF signals corresponding to the data recorded on the optical disc, and this reproduction signal is output from the RF signal generating means 70. The RF signal amplitude detector 72 detects the amplitude from the difference between the maximum value and the minimum value of the reproduction signal output from the RF signal generator 70. FIG. 12 shows the output signal of the RF signal generating means 70 in the section T1 when the target layer is detected and in the section T2 when the layer different from the target is detected, and the difference between the maximum value V11 and the minimum value V12 is shown. From this, the amplitude V3 is detected. The amplitude V4 is detected from the difference between the maximum value V21 and the minimum value V22.

Next, the RF signal amplitude comparison means 73 will be described.
By comparing the RF signal amplitude value output from the RF signal amplitude detection means 72 with the value stored in the threshold storage means 71, the RF signal amplitude detection means 72 is greater than the value stored in the threshold storage means 71. When the RF signal amplitude value output from is larger, an arbitrary value determined in advance is output. Let this arbitrary value be the value a. If the RF signal amplitude value output from the RF signal amplitude detection means 72 is compared with the value stored in the threshold value storage means 71, the RF signal amplitude value is detected from the value stored in the threshold value storage means 71. When the reproduction signal amplitude value output from the means 72 is smaller, a value other than the arbitrary value a is output.

  Further, the value output from the RF signal amplitude comparison unit 73 may be the following value. That is, it may be a difference value between the value output from the RF signal amplitude detection means 72 and the value stored in the threshold value storage means 71.

Next, the threshold storage unit 71 will be described.
The threshold value storage means 71 stores an arbitrary value of 90% or less and 20% or more of the reproduction signal amplitude value in a state where the minute spot is focused on the target layer and the spherical aberration is corrected. Yes. Here, 90% or less is set so that the reproduction signal amplitude value in a state where the minute spot is focused on the target layer and the spherical aberration is corrected, and the minute spot is smaller than the target layer. This is because the upper limit value can be discriminated from the state where the focus is in focus but the spherical aberration is not corrected. Further, 20% or more is the reproduction signal amplitude value in a state where the fine spot is focused on the target layer and the spherical aberration is corrected, and the focus of the fine spot on the target layer. This is because the lower limit value can be discriminated from the state in which the spherical aberration is not corrected.

Next, the layer determination unit 37 will be described.
The layer determination unit 37 determines whether the minute spot is focused on the target layer or whether the minute spot is focused on a layer other than the target, based on the signal output from the RF signal amplitude comparison unit 73. To do. The determination method is as follows. For example, as described in the description of the RF signal amplitude comparison unit 73, when the value output from the RF signal amplitude comparison unit 73 is a value a, the minute spot is focused on the target layer. If the value output from the RF signal amplitude comparing means 73 is other than the value a, it is determined that the minute spot is in focus other than the target layer. Further, when the difference value between the value output from the RF signal amplitude detection means 72 and the value stored in the threshold value storage means 71 is output from the RF signal amplitude comparison means 73, the RF signal amplitude comparison means This is determined by the polarity of the value output from 73. That is, when the layer is determined by the following calculation formula, if the output value from the RF signal amplitude comparing means 73 is positive, it is determined that the target spot is focused on the minute spot, and the negative value cannot be obtained. For example, it is determined that the minute spot is focused on a layer other than the target layer. If the output value from the RF signal amplitude comparison means 73 is E07, the value output from the RF signal amplitude detection means 72 is ES7, and the value stored in the threshold value storage means 71 is ER7,
E07 = ES7-ER7
Further, when the layer is determined by the following calculation formula, if the output value from the RF signal amplitude comparison means 73 becomes a negative electrode, it is determined that the target spot is focused on the minute spot, and the positive electrode cannot be made positive. For example, it is determined that the minute spot is focused on a layer other than the target layer.

E07 = ER7-ES7
Based on the determination result, the layer determination unit 37 sends an instruction to the actuator driving unit 38 to focus the minute spot on the target layer if the layer other than the target is in focus. .

Next, the layer determination procedure of this embodiment will be described.
First, the type and number of layers of the optical disc 6 are discriminated by the control means 39. Next, after the layer to be focused on the minute spot is determined, the correction amount information obtained from the aberration correction amount storage means 31 is used to correct the aberration that occurs when focusing on the target layer. Thus, the aberration correction element driving means 26 is controlled by the control means 39 to drive the liquid crystal aberration correction element 4. Next, the control means 39 controls the actuator drive means 38 based on the signals obtained from the photodetectors 8 and 9 and the focus error detection means 32, and drives the actuator 7 to make a minute amount on the target layer of the optical disk 6. Performs spot focusing. On the other hand, the RF signal generating means 70 outputs a reproduction signal corresponding to the data recorded on the optical disk 6 based on the signals output from the photodetectors 8 and 9. The RF signal amplitude detection means 72 calculates the amplitude of the reproduction signal from the difference between the maximum value and the minimum value of the signal from the RF signal generation means 70. The RF signal amplitude comparison means 73 compares the calculated amplitude of the reproduction signal with the value of the threshold value storage means, and outputs the result. Based on the result of the RF signal amplitude comparison unit 73, the layer determination unit 37 outputs a signal for determining whether the focus of the minute spot is on the target layer or on a layer other than the target. To do. After determining that the layer of the optical disc 6 is in focus, the control unit 39 determines whether or not the minute spot is focused on the target layer of the optical disc 6 based on the signal from the layer determination unit 37. If it is determined that the fine spot is focused on a layer other than the target of the optical disc 6, the control means 39 drives the actuator 7 to the actuator driving means 38 so as to quickly focus on the target layer. Control is performed so that they are adjusted again. As a result, a stable error signal can be obtained in the servo control performed on this recording layer in a short time, and data can be normally reproduced and recorded on the target layer of the optical disc 6. It becomes like this.

  In the optical disk apparatus according to the present embodiment, it is possible to detect that the focal point is focused on the layer other than the target by using the spherical aberration generated when the minute spot is mistakenly focused on the layer other than the target. There is an effect that the operation of refocusing the minute spot on the target layer can be performed.

  In the present embodiment, the correction amount of spherical aberration stored in the aberration correction amount storage means 31 can be determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control. An average value may be used. When the correction amount of the spherical aberration is determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control, the correction amount is selected and switched according to the type of the disc and the target layer.

  The spherical aberration correction amount stored in the aberration correction amount storage means 31 may be the spherical aberration correction amount of the liquid crystal aberration correction element 4 when the optical disk apparatus is assembled and adjusted using the optical disk 6 having the reference thickness. You may set from the standard value of the base-material thickness of the optical disk 6. FIG.

  In the present embodiment, each time the optical disk device is started, the value stored in the threshold storage unit 71 may be reset by the following method. That is, the value stored in the threshold value storage means 71 is the magnitude of the signal amplitude detected by the RF signal amplitude detection means 72 after the actuator 7 is driven by the actuator drive means 38 and a minute spot converges on an arbitrary layer. The value learned from the above may be reset as a threshold for an arbitrary layer. By correcting the threshold value by such a method, an error in the output from the RF signal amplitude comparison unit 73 due to the influence of a change in the reproduction signal with time or a temperature change can be minimized, and the determination result of the layer determination unit 37 can be obtained. It is possible to eliminate errors.

  In the present embodiment, each time the optical disk device is started, the value stored in the threshold storage unit 71 may be reset by the following method. That is, the value stored in the threshold value storage means 71 sets the drive amount of the aberration correction element drive means 26 to an optimum drive amount for the target layer, and drives the actuator 7 by the actuator drive means 38 so that it can be set to any layer. The magnitude of the signal amplitude detected by the RF signal amplitude detection means 72 after the fine spot has converged and the driving amount of the aberration correction element driving means 26 are set to an optimum driving amount other than the target layer, and an arbitrary layer Alternatively, an intermediate value between the magnitude of the signal amplitude detected by the RF signal amplitude detection means 72 after the minute spot has converged may be reset as a threshold for an arbitrary layer. By correcting the threshold value by such a method, an error in the output from the RF signal amplitude comparison unit 73 due to the influence of a change in the reproduction signal with time or a temperature change can be minimized, and the determination result of the layer determination unit 37 can be obtained. It is possible to eliminate errors.

(Embodiment 8)
FIG. 8 shows an optical disc apparatus according to an eighth embodiment of the present invention.
Note that the same components as those in the above-described seventh embodiment are described with the same reference numerals.

  The optical disk apparatus according to the present embodiment includes the same optical pickup 11 as in FIG. 14 described in the conventional example, an aberration correction element driving unit 26 that drives the liquid crystal aberration correction element 4 as an aberration correction unit, and at least two or more pluralities. Aberration correction amount storage means 31 for storing the aberration correction amount for each layer of the optical disk 6 composed of a plurality of layers, actuator drive means 38 for driving the objective lens 5, and a signal obtained from the optical pickup 11 are received and converged on the optical disk 6. From the focus error detection means 32 for detecting the convergence state of the minute spot, the RF signal generation means 70 for generating a signal for reproducing the data recorded on the optical disc 6, and the focus error detection means 32 Based on the output signal and the output signal from the RF signal generating means 70, the laser beam is focused on the disk. Actuator driving means 38 for driving the lens 5, RF signal level detecting means 78 for detecting the level of the reproduction signal based on the output signal from the RF signal generating means 70, and a signal and threshold value storage from the RF signal level detecting means 78 Based on the RF signal level comparison means 79 for comparing the threshold value stored in the means 77 and the result output from the RF signal level comparison means 79, it is determined whether or not the minute spot has converged on the target layer. If the minute spot is focused on a layer other than the target, a layer determination unit that gives an instruction to the actuator driving unit 38 to drive the actuator 7 to focus the minute spot on the target layer 37, the output signals from the photodetectors 8 and 9, the signal from the focus error detection means 32, and the signal from the RF signal generation means 70. The information signal obtained from the optical pickup 11 is improved by discriminating the type of the optical disk, causing the laser light source 1 to emit light, controlling the actuator driving means 38, or driving the aberration correction element driving means 26. In addition, when the focus is drawn into a layer other than the target based on a signal from the layer determination unit 37, the control unit 39 performs processing for drawing the focus into the target layer again.

The configuration of the optical pickup 11 is the same as that described with reference to FIG. 14, and the same components as those in FIG.
Next, the RF signal level detection means 78 will be described.

  In a state in which the fine spot is focused on an arbitrary layer of the optical disc 6, light is irradiated to the pits formed on the recording surface of the disc, and the light reflected from the optical disc is detected by the photodetectors 8, 9 is incident. Light incident on the photodetectors 8 and 9 is photoelectrically converted and output. The signals output from the photodetectors 8 and 9 are output from the RF signal generating means 70 as a reproduction signal for reproducing the data recorded on the optical disc. The RF signal level detection unit 78 detects the maximum value of the reproduction signal output from the RF signal generation unit 70.

  FIG. 13 shows the output signal of the RF signal generation means 70 in the section T1 when the target layer is normally detected and the section T2 when the layer different from the target is detected. The RF signal level detection means 78 is shown in FIG. The maximum values V11 and V21 of the reproduction signal are detected. Here, the operation of the optical disc apparatus is described assuming that the RF signal level detection means 78 detects the maximum value of the reproduction signal, but the RF signal level detection means 78 determines the minimum values V12 and V22 of the reproduction signal. The optical disc apparatus can be configured by detecting the optical disc device.

Next, the RF signal level comparison means 79 will be described.
The reproduction signal level value output from the RF signal level detection means 78 is compared with the value stored in the threshold value storage means 77, and if the value stored in the threshold value storage means 77 is greater than the RF signal level detection means 78. When the reproduction signal level value output from is larger, an arbitrary value determined in advance is output. Let this arbitrary value be the value a. If the reproduction signal level value output from the RF signal level detection means 78 is compared with the value stored in the threshold storage means 77, the RF signal level detection is greater than the value stored in the threshold storage means 77. When the reproduction signal level value output from the means 78 is smaller, a value other than the arbitrary value a is output.

  Further, the value output from the RF signal level comparison means 79 may be the following value. That is, it may be a difference value between the value output from the RF signal level detection unit 78 and the value stored in the threshold storage unit 77.

Next, the threshold storage unit 77 will be described.
The threshold value storage means 77 stores an arbitrary value that is 90% or less and 20% or more of the reproduction signal level value in a state where the minute spot is focused on the target layer and the spherical aberration is corrected. Yes. Here, 90% or less is set so that the reproduced signal level value in a state where the minute spot is focused on the target layer and the spherical aberration is corrected, and the minute spot is smaller than the target layer. This is because the upper limit value can be discriminated from the state where the in-focus state is not corrected. Further, 20% or more is the reproduction signal level value when the minute spot is focused on the target layer and the spherical aberration is corrected, and the focus of the minute spot on the target layer. This is because the lower limit value can be discriminated from the state in which the spherical aberration is not corrected.

Next, the layer determination unit 37 will be described.
The layer determination unit 37 determines whether the minute spot is focused on the target layer or the minute spot is focused on a layer other than the target, based on the signal output from the RF signal level comparison unit 79. To do. The determination method is as follows. For example, as described in the description of the RF signal level comparison unit 79, when the value output from the RF signal level comparison unit 79 is a value a, the minute spot is focused on the target layer. If the value output from the RF signal level comparing means 79 is other than the value a, it is determined that the minute spot is in focus other than the target layer. When the difference between the value output from the RF signal level detection means 78 and the value stored in the threshold storage means 77 is output from the RF signal level comparison means 79, the RF signal level comparison means This is determined by the polarity of the value output from 79. That is, when the layer is determined by the following calculation formula, if the output value from the RF signal level comparison means 79 is positive, it is determined that the target spot is focused on the minute spot, and cannot be negative. For example, it is determined that the minute spot is focused on a layer other than the target layer.

If the output value from the RF signal level comparison means 79 is E08, the value output from the RF signal level detection means 78 is ES8, and the value stored in the threshold value storage means 77 is ER8,
E08 = ES8-ER8
Also, when the layer is determined by the following calculation formula, if the output value from the RF signal level comparing means 79 becomes a negative electrode, it is determined that the target spot is focused on the minute spot, and the positive electrode cannot be used. For example, it is determined that the minute spot is focused on a layer other than the target layer.

E08 = ER8-ES8
Based on the determination result, the layer determination unit 37 sends an instruction to the actuator driving unit 38 to focus the minute spot on the target layer if the layer other than the target is in focus. .

Next, the layer determination procedure of this embodiment will be described.
First, the type and number of layers of the optical disc 6 are discriminated by the control means 39. Next, after the layer to be focused on the minute spot is determined, the correction amount information obtained from the aberration correction amount storage means 31 is used to correct the aberration that occurs when focusing on the target layer. Thus, the aberration correction element driving means 26 is controlled by the control means 39 to drive the liquid crystal aberration correction element 4. Next, the control means 39 controls the actuator drive means 38 based on the signals obtained from the photodetectors 8 and 9 and the focus error detection means 32, and drives the actuator 7 to make a minute amount on the target layer of the optical disk 6. Performs spot focusing. On the other hand, the RF signal generating means 70 outputs a reproduction signal corresponding to the data recorded on the optical disk 6 based on the signals output from the photodetectors 8 and 9. The RF signal level detection unit 78 calculates the level of the reproduction signal from the maximum value of the signal from the RF signal generation unit 70. The RF signal level comparison means 79 compares the calculated reproduction signal level with the value of the threshold value storage means and outputs the result. Based on the result of the RF signal level comparing means 79, the layer determining means 37 outputs a signal for determining whether the focus of the minute spot is on the target layer or on a layer other than the target. To do. After determining that the layer of the optical disc 6 is in focus, the control unit 39 determines whether or not the minute spot is focused on the target layer of the optical disc 6 based on the signal from the layer determination unit 37. If it is determined that the fine spot is focused on a layer other than the target of the optical disc 6, the control means 39 drives the actuator 7 to the actuator driving means 38 so as to quickly focus on the target layer. Control is performed so that they are adjusted again. As a result, a stable error signal can be obtained in the servo control performed on this recording layer in a short time, and data can be normally reproduced and recorded on the target layer of the optical disc 6. It becomes like this.

  In the optical disk apparatus according to the present embodiment, it is possible to detect that the focal point is focused on the layer other than the target by using the spherical aberration generated when the minute spot is mistakenly focused on the layer other than the target. There is an effect that the operation of refocusing the minute spot on the target layer can be performed.

  In the present embodiment, the correction amount of spherical aberration stored in the aberration correction amount storage means 31 can be determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control. An average value may be used. When the correction amount of the spherical aberration is determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control, the correction amount is selected and switched according to the type of the disc and the target layer.

  The spherical aberration correction amount stored in the aberration correction amount storage means 31 may be the spherical aberration correction amount of the liquid crystal aberration correction element 4 when the optical disk apparatus is assembled and adjusted using the optical disk 6 having the reference thickness. You may set from the standard value of the base-material thickness of the optical disk 6. FIG.

  In the present embodiment, each time the optical disk device is started, the value stored in the threshold storage unit 77 may be reset by the following method. That is, the value stored in the threshold value storage unit 77 is the magnitude of the signal level detected by the RF signal level detection unit 78 after the actuator 7 is driven by the actuator drive unit 38 and a minute spot converges on an arbitrary layer. The value learned from the above may be reset as a threshold for an arbitrary layer. By correcting the threshold value by such a method, an error in output from the RF signal level comparison unit 79 due to the influence of a change in the reproduction signal with time or a temperature change can be minimized, and the determination result of the layer determination unit 37 It is possible to eliminate errors.

  In the present embodiment, each time the optical disk device is started, the value stored in the threshold storage unit 77 may be reset by the following method. That is, the value stored in the threshold value storage unit 77 is such that the driving amount of the aberration correction element driving unit 26 is an optimal driving amount for the target layer, and the actuator driving unit 38 drives the actuator 7 so that it can be stored in any layer. The magnitude of the signal level detected by the RF signal level detection means 78 after the minute spot has converged and the drive amount of the aberration correction element drive means 26 are set to an optimum drive amount other than the target layer, and an arbitrary layer Alternatively, an intermediate value between the magnitude of the signal level detected by the RF signal level detection means 78 after the minute spot has converged may be reset as a threshold value for an arbitrary layer. By correcting the threshold value by such a method, an error in output from the RF signal level comparison unit 79 due to the influence of a change in the reproduction signal with time or a temperature change can be minimized, and the determination result of the layer determination unit 37 It is possible to eliminate errors.

(Embodiment 9)
FIG. 9 shows an optical disc apparatus according to Embodiment 9 of the present invention.
Note that the same components as those in the above-described eighth embodiment will be described with the same reference numerals.

  The optical disk apparatus according to the present embodiment includes the same optical pickup 11 as in FIG. 14 described in the conventional example, an aberration correction element driving unit 26 that drives the liquid crystal aberration correction element 4 as an aberration correction unit, and at least two or more pluralities. Aberration correction amount storage means 31 for storing the aberration correction amount for each layer of the optical disk 6 composed of a plurality of layers, actuator drive means 38 for driving the objective lens 5, and a signal obtained from the optical pickup 11 are received and converged on the optical disk 6. From the focus error detection means 32 for detecting the convergence state of the minute spot, the RF signal generation means 70 for generating a signal for reproducing the data recorded on the optical disc 6, and the focus error detection means 32 Based on the output signal and the output signal from the RF signal generating means 70, the laser beam is focused on the disk. Actuator drive means 38 for driving the lens 5, RF signal AGC detection means 84 for detecting a deviation between the amplitude of the reproduction signal 80 output from the RF signal generation means 70 and the target amplitude, and output from the RF signal AGC detection means 84 Is stored in the threshold value storage means 83 and the signal from the RF signal AGC detection means 84 and the RF signal amplification means 82 for amplifying the reproduction signal 81 input to the control means 39 to keep the amplitude constant. The RF signal AGC value comparison means 85 for comparing the threshold value and the result output from the RF signal AGC value comparison means 85 determines whether or not the minute spot has converged on the target layer. If the microspot is in focus on the target layer, the actuator 7 is driven to drive the actuator 7 to focus the microspot on the target layer. The type of the optical disc based on the layer determination means 37 for giving an instruction to the data drive means 38, the output signals from the photodetectors 8 and 9, the signal from the focus error detection means 32, and the signal from the RF signal generation means 70 , The laser light source 1 is made to emit light, the actuator driving means 38 is controlled, the aberration correction element driving means 26 is driven to improve the information signal obtained from the optical pickup 11, and the layer Based on the signal from the determination means 37, when the focus is drawn into a layer other than the target, the control means 39 for performing the process of drawing the focus into the target layer again is provided.

The configuration of the optical pickup 11 is the same as that described with reference to FIG. 14, and the same components as those in FIG.
Next, the RF signal AGC detection means 84 will be described.

  In a state in which the fine spot is focused on an arbitrary layer of the optical disc 6, light is irradiated to the pits formed on the recording surface of the disc, and the light reflected from the optical disc is detected by the photodetectors 8, 9 is incident. Light incident on the photodetectors 8 and 9 is photoelectrically converted and output. The signals output from the photodetectors 8 and 9 are RF signals corresponding to the data recorded on the optical disc, and this reproduction signal is output from the RF signal generating means 70. The RF signal AGC detection unit 84 detects the value of the ratio between the amplitude of the reproduction signal 80 and the amplitude target value output from the RF signal generation unit 70.

Next, the RF signal AGC value comparison means 85 will be described.
The reproduction signal AGC value output from the RF signal AGC detection means 84 is compared with the value stored in the threshold storage means 83, and if the value stored in the threshold storage means 83 is greater than the value stored in the threshold storage means 83. When the reproduction signal AGC value output from is smaller, any predetermined value is output. Let this arbitrary value be the value a. If the reproduction signal AGC value output from the RF signal AGC detection means 84 is compared with the value stored in the threshold storage means 83, the RF signal AGC detection is detected more than the value stored in the threshold storage means 83. When the reproduction signal AGC value output from the means 84 is larger, a value other than the arbitrary value a is output.

  The value output from the RF signal AGC value comparison unit 85 may be the following value. That is, it may be a difference value between the value output from the RF signal AGC detection unit 84 and the value stored in the threshold storage unit 83.

Next, the threshold storage unit 83 will be described.
The threshold storage means 83 stores an arbitrary value of 90% or less and 20% or more of the reproduction signal AGC value in a state where the minute spot is focused on the target layer and the spherical aberration is corrected. Yes. Here, 90% or less is the value of the reproduction signal AGC value in a state where the minute spot is focused on the target layer and the spherical aberration is corrected, and the minute spot is smaller than the target layer. This is because the upper limit value can be discriminated from the state where the focus is in focus but the spherical aberration is not corrected. Further, 20% or more is the reproduction signal AGC value in a state where the minute spot is focused on the target layer and the spherical aberration is corrected, and the focal point of the minute spot on the target layer. This is because the lower limit value can be determined from which the spherical aberration is not corrected.

Next, the layer determination unit 37 will be described.
In the layer determination unit 37, whether the minute spot is focused on the target layer or the layer other than the target is focused by the signal output from the RF signal AGC value comparison unit 85. judge. The determination method is as follows. For example, as described in the description of the RF signal AGC value comparison unit 85, when the value output from the RF signal AGC value comparison unit 85 is the value a, the minute spot is focused on the target layer. If the value output from the RF signal AGC value comparison means 85 is other than the value a, it is determined that the minute spot is in focus other than the target layer. When the difference between the value output from the RF signal AGC detection unit 84 and the value stored in the threshold storage unit 83 is output from the reproduction signal AGC value comparison unit 85, the RF signal AGC value This is determined by the polarity of the value output from the comparison means 85. That is, when the layer is determined by the following calculation formula, if the output value from the RF signal AGC value comparing means 85 becomes the negative electrode, it is determined that the minute spot is focused on the target layer, and the positive electrode is applied. If so, it is determined that the fine spot is focused on a layer other than the target layer. If the output value from the RF signal AGC value comparison means 85 is E09, the value output from the RF signal AGC detection means 84 is ES9, and the value stored in the threshold value storage means 83 is ER9,
E09 = ES9-ER9
In addition, when the layer is determined by the following calculation formula, if the output value from the RF signal AGC value comparison means 85 becomes the positive electrode, it is determined that the minute spot is focused on the target layer, and the negative electrode If so, it is determined that the fine spot is focused on a layer other than the target layer.

E09 = ER9-ES9
Based on the determination result, the layer determination unit 37 sends an instruction to the actuator driving unit 38 to focus the minute spot on the target layer if the layer other than the target is in focus. .

Next, the layer determination procedure of this embodiment will be described.
First, the type and number of layers of the optical disc 6 are discriminated by the control means 39. Next, after the layer to be focused on the minute spot is determined, the correction amount information obtained from the aberration correction amount storage means 31 is used to correct the aberration that occurs when focusing on the target layer. Thus, the aberration correction element driving means 26 is controlled by the control means 39 to drive the liquid crystal aberration correction element 4. Next, the control means 39 controls the actuator drive means 38 based on the signals obtained from the photodetectors 8 and 9 and the focus error detection means 32, and drives the actuator 7 to make a minute amount on the target layer of the optical disk 6. Performs spot focusing. On the other hand, the RF signal generating means 70 outputs a reproduction signal corresponding to the data recorded on the optical disk 6 based on the signals output from the photodetectors 8 and 9. The RF signal AGC detection means 84 calculates the AGC value of the reproduction signal from the difference between the maximum value and the minimum value of the signal from the RF signal generation means 70. The RF signal AGC value comparison means 85 compares the calculated AGC value of the reproduction signal with the value of the threshold value storage means, and outputs the result. Based on the result of the RF signal AGC value comparison unit 85, the layer determination unit 37 generates a signal for determining whether the focus of the minute spot is on the target layer or on a layer other than the target. Output. After determining that the layer of the optical disc 6 is in focus, the control unit 39 determines whether or not the minute spot is focused on the target layer of the optical disc 6 based on the signal from the layer determination unit 37. If it is determined that the fine spot is focused on a layer other than the target of the optical disc 6, the control means 39 drives the actuator 7 to the actuator driving means 38 so as to quickly focus on the target layer. Control is performed so that they are adjusted again. As a result, a stable error signal can be obtained in the servo control performed on this recording layer in a short time, and data can be normally reproduced and recorded on the target layer of the optical disc 6. It becomes like this.

  In the optical disk apparatus according to the present embodiment, it is possible to detect that the focal point is focused on the layer other than the target by using the spherical aberration generated when the minute spot is mistakenly focused on the layer other than the target. There is an effect that the operation of refocusing the minute spot on the target layer can be performed.

  In the present embodiment, the correction amount of spherical aberration stored in the aberration correction amount storage means 31 can be determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control. An average value may be used. When the correction amount of the spherical aberration is determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control, the correction amount is selected and switched according to the type of the disc and the target layer.

  The spherical aberration correction amount stored in the aberration correction amount storage means 31 may be the spherical aberration correction amount of the liquid crystal aberration correction element 4 when the optical disk apparatus is assembled and adjusted using the optical disk 6 having the reference thickness. You may set from the standard value of the base-material thickness of the optical disk 6. FIG.

  In the present embodiment, each time the optical disk device is started, the value stored in the threshold storage unit 83 may be reset by the following method. That is, the value stored in the threshold value storage means 83 is the magnitude of the signal level detected by the RF signal AGC detection means 84 after the actuator 7 is driven by the actuator drive means 38 and the minute spot converges on an arbitrary layer. The value learned from the above may be reset as a threshold for an arbitrary layer. By correcting the threshold value by such a method, an error in the output from the RF signal AGC value comparison means 85 due to the influence of the change in the reproduction signal with time or the temperature change can be minimized, and the determination result by the layer determination means 37 It is possible to eliminate the error.

  In the present embodiment, each time the optical disk device is started, the value stored in the threshold storage unit 83 may be reset by the following method. That is, the value stored in the threshold value storage unit 83 sets the driving amount of the aberration correction element driving unit 26 to an optimum driving amount for the target layer, and drives the actuator 7 by the actuator driving unit 38 so as to be set to an arbitrary layer. The magnitude of the signal level detected by the RF signal AGC detection means 84 after the fine spot has converged and the drive amount of the aberration correction element drive means 26 are set to an optimum drive amount other than the target layer, and any layer Alternatively, an intermediate value between the magnitude of the signal level detected by the RF signal AGC detection means 84 after the minute spot has converged may be reset as a threshold for an arbitrary layer. By correcting the threshold value by such a method, an error in the output from the RF signal AGC value comparison means 85 due to the influence of the change in the reproduction signal with time or the temperature change can be minimized, and the determination result by the layer determination means 37 It is possible to eliminate the error.

(Embodiment 10)
FIG. 10 shows an optical disk device according to a tenth embodiment of the present invention.
Note that the same components as those in the ninth embodiment are described with the same reference numerals.

  The optical disk apparatus according to the present embodiment includes the same optical pickup 11 as in FIG. 14 described in the conventional example, an aberration correction element driving unit 26 that drives the liquid crystal aberration correction element 4 as an aberration correction unit, and at least two or more pluralities. Aberration correction amount storage means 31 for storing the aberration correction amount for each layer of the optical disk 6 composed of a plurality of layers, actuator drive means 38 for driving the objective lens 5, and a signal obtained from the optical pickup 11 are received and converged on the optical disk 6. From the focus error detection means 32 for detecting the convergence state of the minute spot, the RF signal generation means 70 for generating a signal for reproducing the data recorded on the optical disc 6, and the focus error detection means 32 Based on the output signal and the output signal from the RF signal generating means 70, the laser beam is focused on the disk. Actuator driving means 38 for driving the lens 5, RF envelope signal detecting means 87 for detecting the envelope of the reproduction signal based on the output signal from the RF signal generating means 70, signals from the RF envelope signal detecting means 87 and threshold value storage Based on the result output from the RF envelope level comparison means 88 and the RF envelope level comparison means 88 that compares the threshold value stored in the means 86, it is determined whether or not the minute spot has converged on the target layer. If the minute spot is focused on a layer other than the target, a layer determination unit that gives an instruction to the actuator driving unit 38 to drive the actuator 7 to focus the minute spot on the target layer 37, the output signal from the photodetectors 8 and 9, and the signal from the focus error detection means 32. Or discriminating the type of the optical disk based on the signal from the RF signal generating means 70, causing the laser light source 1 to emit light, controlling the actuator driving means 38, or driving the aberration correcting element driving means 26; If the information signal obtained from the optical pickup 11 is improved, or if the focus is drawn into a layer other than the target based on the signal from the layer determination unit 37, the process of drawing the focus back into the target layer is performed. And control means 39.

The configuration of the optical pickup 11 is the same as that described with reference to FIG. 14, and the same components as those in FIG.
Next, the RF envelope signal detection means 87 will be described.

  In a state in which the fine spot is focused on an arbitrary layer of the optical disc 6, light is irradiated to the pits formed on the recording surface of the disc, and the light reflected from the optical disc is detected by the photodetectors 8, 9 is incident. Light incident on the photodetectors 8 and 9 is photoelectrically converted and output. The signals output from the photodetectors 8 and 9 are RF signals corresponding to the data recorded on the optical disc, and this reproduction signal is output from the RF signal generating means 70. The RF envelope signal detection means 87 detects the envelope of the reproduction signal output from the RF signal generation means 70.

Next, the RF envelope level comparison means 88 will be described.
The RF envelope signal level value output from the RF envelope signal detection means 87 is compared with the value stored in the threshold value storage means 86. If the value stored in the threshold value storage means 86 is greater than the RF envelope signal detection means. When the reproduction signal envelope level value output from 87 is larger, a predetermined arbitrary value is output. Let this arbitrary value be the value a. If the reproduction signal envelope level value output from the RF envelope signal detection means 87 is compared with the value stored in the threshold storage means 86, the RF envelope signal is greater than the value stored in the threshold storage means 86. When the reproduction signal envelope level value output from the detection means 87 is smaller, a value other than the arbitrary value a is output.

  Further, the value output from the RF envelope level comparing means 88 may be the following value. That is, it may be a difference value between the value output from the RF envelope signal detection means 87 and the value stored in the threshold value storage means 86.

Next, the threshold storage unit 86 will be described.
The threshold value storage means 86 stores an arbitrary value not less than 90% and not less than 20% of the reproduction signal envelope level value when the minute spot is focused on the target layer and the spherical aberration is corrected. ing. Here, 90% or less is the reproduction signal envelope level value in a state where the minute spot is focused on the target layer and the spherical aberration is corrected, and the minute spot with respect to the target layer. This is because the upper limit value can be discriminated from the state in which the spherical aberration is not corrected. Further, 20% or more is that the reproduction spot envelope level value when the minute spot is focused on the target layer and the spherical aberration is corrected, and the minute spot is smaller than the target layer. This is because the lower limit value can be discriminated from the state in which the lens is in focus but the spherical aberration is not corrected.

Next, the layer determination unit 37 will be described.
The layer determination unit 37 determines whether the minute spot is focused on the target layer or whether the minute spot is focused on a layer other than the target, based on the signal output from the RF envelope level comparison unit 88. To do. The determination method is as follows. For example, as described in the section of the RF envelope level comparison unit 88, when the value output from the RF envelope level comparison unit 88 is a value a, the target spot is focused on the minute spot. If the value output from the RF envelope level comparing means 88 is other than the value a, it is determined that the minute spot is in focus other than the target layer. Further, when the difference value between the value output from the RF envelope signal detection means 87 and the value stored in the threshold value storage means 86 is output from the RF envelope level comparison means 88, the RF envelope level comparison means This is determined by the polarity of the value output from 88. In other words, when the layer is determined by the following calculation formula, if the output value from the RF envelope level comparison means 88 is positive, it is determined that the target spot is focused on the minute spot and cannot be negative. For example, it is determined that the minute spot is focused on a layer other than the target layer. If the output value from the RF envelope level comparison means 88 is E010, the value output from the RF envelope signal detection means 87 is ES10, and the value stored in the threshold storage means 86 is ER10,
E010 = ES10-ER10
Also, when the layer is determined by the following calculation formula, if the output value from the RF envelope level comparison means 88 is a negative electrode, it is determined that the target spot is focused on the minute spot, and the positive electrode cannot be used. For example, it is determined that the minute spot is focused on a layer other than the target layer.

E010 = ER10-ES10
Based on the determination result, the layer determination unit 37 sends an instruction to the actuator driving unit 38 to focus the minute spot on the target layer if the layer other than the target is in focus. .

Next, the layer determination procedure of this embodiment will be described.
First, the type and number of layers of the optical disc 6 are discriminated by the control means 39. Next, after the layer to be focused on the minute spot is determined, the correction amount information obtained from the aberration correction amount storage means 31 is used to correct the aberration that occurs when focusing on the target layer. Thus, the aberration correction element driving means 26 is controlled by the control means 39 to drive the liquid crystal aberration correction element 4. Next, the control means 39 controls the actuator drive means 38 based on the signals obtained from the photodetectors 8 and 9 and the focus error detection means 32, and drives the actuator 7 to make a minute amount on the target layer of the optical disk 6. Performs spot focusing. On the other hand, the RF signal generating means 70 outputs a reproduction signal corresponding to the data recorded on the optical disk 6 based on the signals output from the photodetectors 8 and 9. The RF envelope signal detector 87 calculates the envelope of the RF signal from the output signal of the RF signal generator 70. The RF envelope level comparison means 88 compares the calculated envelope level of the RF signal with the value of the threshold value storage means, and outputs the result. Based on the result of the RF envelope level comparison unit 88, the layer determination unit 37 outputs a signal for determining whether the focus of the minute spot is on the target layer or on a layer other than the target layer. To do. After determining that the layer of the optical disc 6 is in focus, the control unit 39 determines whether or not the minute spot is focused on the target layer of the optical disc 6 based on the signal from the layer determination unit 37. If it is determined that the fine spot is focused on a layer other than the target of the optical disc 6, the control means 39 drives the actuator 7 to the actuator driving means 38 so as to quickly focus on the target layer. Control is performed so that they are adjusted again. As a result, a stable error signal can be obtained in the servo control performed on this recording layer in a short time, and data can be normally reproduced and recorded on the target layer of the optical disc 6. It becomes like this.

  In the optical disk apparatus according to the present embodiment, it is possible to detect that the focal point is focused on the layer other than the target by using the spherical aberration generated when the minute spot is mistakenly focused on the layer other than the target. There is an effect that the operation of refocusing the minute spot on the target layer can be performed.

  In the present embodiment, the correction amount of spherical aberration stored in the aberration correction amount storage means 31 can be determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control. An average value may be used. When the correction amount of the spherical aberration is determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control, the correction amount is selected and switched according to the type of the disc and the target layer.

  The spherical aberration correction amount stored in the aberration correction amount storage means 31 may be the spherical aberration correction amount of the liquid crystal aberration correction element 4 when the optical disk apparatus is assembled and adjusted using the optical disk 6 having the reference thickness. You may set from the standard value of the base-material thickness of the optical disk 6. FIG.

  In the present embodiment, each time the optical disk device is started, the value stored in the threshold storage unit 86 may be reset by the following method. That is, the value stored in the threshold value storage means 86 is the magnitude of the signal level detected by the RF envelope signal detection means 87 after the actuator 7 is driven by the actuator drive means 38 and a minute spot converges on an arbitrary layer. The value learned from the above may be reset as a threshold for an arbitrary layer. By correcting the threshold value by such a method, an error in the output from the RF envelope level comparison unit 88 due to the influence of a change in the RF signal with time or a change in temperature can be minimized, and the determination result of the layer determination unit 37 can be reduced. It is possible to eliminate errors.

  In the present embodiment, each time the optical disk device is started, the value stored in the threshold storage unit 86 may be reset by the following method. That is, the value stored in the threshold value storage means 86 is such that the driving amount of the aberration correction element driving means 26 is set to the optimum driving amount for the target layer, and the actuator 7 is driven by the actuator driving means 38 to be set to an arbitrary layer. The magnitude of the signal level detected by the RF envelope signal detection means 87 after the fine spot has converged and the drive amount of the aberration correction element drive means 26 are set to an optimum drive amount other than the target layer, and an arbitrary layer Alternatively, an intermediate value between the magnitude of the signal level detected by the RF envelope signal detection means 87 after the minute spot has converged may be reset as a threshold for an arbitrary layer. By correcting the threshold value by such a method, an error in the output from the RF envelope level comparison unit 88 due to the influence of a change in the RF signal with time or a change in temperature can be minimized, and the determination result of the layer determination unit 37 can be reduced. It is possible to eliminate errors.

(Embodiment 11)
FIG. 11 shows an optical disc apparatus according to an eleventh embodiment of the present invention.
Note that the same components as those in the tenth embodiment described above will be described with the same reference numerals.

  The optical disk apparatus according to the present embodiment includes the same optical pickup 11 as in FIG. 14 described in the conventional example, an aberration correction element driving unit 26 that drives the liquid crystal aberration correction element 4 as an aberration correction unit, and at least two or more pluralities. Aberration correction amount storage means 31 for storing the aberration correction amount for each layer of the optical disk 6 composed of a plurality of layers, actuator drive means 38 for driving the objective lens 5, and a signal obtained from the optical pickup 11 are received and converged on the optical disk 6. From the focus error detection means 32 for detecting the convergence state of the minute spot, the RF signal generation means 70 for generating a signal for reproducing the data recorded on the optical disc 6, and the focus error detection means 32 Based on the output signal and the output signal from the RF signal generating means 70, the laser beam is focused on the disk. Actuator driving means 38 for driving the lens 5, RF signal jitter detecting means 75 for detecting the jitter value of the RF signal based on the output signal from the RF signal generating means 70, signals from the RF signal jitter detecting means 75 and threshold values Based on the RF jitter value comparison means 76 for comparing the threshold value stored in the storage means 74 and the result output from the RF jitter value comparison means 76, it is determined whether or not the minute spot has converged on the target layer. However, if the minute spot is focused on a layer other than the target, a layer determination that gives an instruction to the actuator driving means 38 to drive the actuator 7 in order to focus the minute spot on the target layer. Means 37, output signals from the photo detectors 8 and 9, signals from the focus error detecting means 32, and RF signal generating means 70 Information obtained from the optical pickup 11 by discriminating the type of the optical disk based on these signals, causing the laser light source 1 to emit light, controlling the actuator driving means 38, or driving the aberration correction element driving means 26. And a control means 39 for performing a process of drawing the focus again into the target layer when the focus is drawn into a layer other than the target based on the signal from the layer determination means 37 and improving the signal. ing.

The configuration of the optical pickup 11 is the same as that described with reference to FIG. 14, and the same components as those in FIG.
Next, the RF signal jitter detection means 75 will be described.

  In a state in which the fine spot is focused on an arbitrary layer of the optical disc 6, light is irradiated to the pits formed on the recording surface of the disc, and the light reflected from the optical disc is detected by the photodetectors 8, 9 is incident. Light incident on the photodetectors 8 and 9 is photoelectrically converted and output. The signals output from the photodetectors 8 and 9 are RF signals corresponding to the data recorded on the optical disc, and this reproduction signal is output from the RF signal generating means 70. The RF signal jitter detector 75 detects the jitter value of the RF signal output from the RF signal generator 70.

Next, the RF jitter value comparison means 76 will be described.
The RF signal jitter value output from the RF signal jitter detection means 75 is compared with the value stored in the threshold value storage means 74, and the RF signal jitter detection means 75 is greater than the value stored in the threshold value storage means 74. When the RF signal jitter value output from is smaller, an arbitrary value determined in advance is output. Let this arbitrary value be the value a. If the RF signal jitter value output from the RF signal jitter detection means 75 is compared with the value stored in the threshold storage means 74, the RF signal jitter detection is greater than the value stored in the threshold storage means 74. When the RF signal jitter value output from the means 75 is larger, a value other than the arbitrary value a is output.

  Further, the value output from the RF signal jitter value comparison means 76 may be the following value. That is, it may be a difference value between the value output from the RF signal jitter detection means 75 and the value stored in the threshold value storage means 74.

Next, the threshold storage unit 74 will be described.
The threshold value storage means 74 stores an arbitrary value of 90% or less and 20% or more of the RF signal jitter value in a state where the minute spot is focused on the target layer and the spherical aberration is corrected. Yes. Here, 90% or less is the RF signal jitter value in a state where the minute spot is focused on the target layer and the spherical aberration is corrected, and the minute spot is smaller than the target layer. This is because the upper limit value can be discriminated from the state where the focus is in focus but the spherical aberration is not corrected. Further, 20% or more is the RF signal jitter value when the fine spot is focused on the target layer and the spherical aberration is corrected, and the fine spot focus on the target layer. This is because the lower limit value can be determined from which the spherical aberration is not corrected.

Next, the layer determination unit 37 will be described.
The layer determining unit 37 determines whether the minute spot is focused on the target layer or the layer other than the target is focused on the signal output from the RF jitter value comparing unit 76. To do. The determination method is as follows. For example, as described in the description section of the RF jitter value comparison unit 76, when the value output from the RF jitter value comparison unit 76 is the value a, the minute spot is focused on the target layer. If the value output from the RF jitter value comparing means 76 is other than the value a, it is determined that the minute spot is in focus other than the target layer. Further, when the difference value between the value output from the RF signal jitter detection means 75 and the value stored in the threshold value storage means 74 is output from the RF jitter value comparison means 76, the RF jitter value comparison means This is determined by the polarity of the value output from 76. That is, when the layer is determined by the following calculation formula, if the output value from the RF jitter value comparing means 76 becomes a negative electrode, it is determined that the minute spot is in focus on the target layer, so that the positive electrode can be obtained. For example, it is determined that the minute spot is focused on a layer other than the target layer. If the output value from the RF jitter value comparison means 76 is E011, the value output from the RF signal jitter detection means 75 is ES11, and the value stored in the threshold value storage means 74 is ER11,
E011 = ES11-ER11
Further, when the layer is determined by the following calculation formula, if the output value from the RF jitter value comparing means 76 becomes a positive electrode, it is determined that the target spot is focused on the minute spot, so that the negative electrode can not be used. For example, it is determined that the minute spot is focused on a layer other than the target layer.

E011 = ER11-ES11
Based on the determination result, the layer determination unit 37 sends an instruction to the actuator driving unit 38 to focus the minute spot on the target layer if the layer other than the target is in focus. .

Next, the layer determination procedure of this embodiment will be described.
First, the type and number of layers of the optical disc 6 are discriminated by the control means 39. Next, after the layer to be focused on the minute spot is determined, the correction amount information obtained from the aberration correction amount storage means 31 is used to correct the aberration that occurs when focusing on the target layer. Thus, the aberration correction element driving means 26 is controlled by the control means 39 to drive the liquid crystal aberration correction element 4. Next, the control means 39 controls the actuator drive means 38 based on the signals obtained from the photodetectors 8 and 9 and the focus error detection means 32, and drives the actuator 7 to make a minute amount on the target layer of the optical disk 6. Performs spot focusing. On the other hand, the RF signal generating means 70 outputs a reproduction signal corresponding to the data recorded on the optical disk 6 based on the signals output from the photodetectors 8 and 9. The RF signal jitter detector 75 calculates the jitter value of the RF signal from the output signal of the RF signal generator 70. The RF jitter value comparison means 76 compares the calculated jitter value of the RF signal with the value of the threshold value storage means, and outputs the result. Based on the result of the RF jitter value comparison unit 76, the layer determination unit 37 outputs a signal for determining whether the focus of the minute spot is on the target layer or on a layer other than the target layer. To do. After determining that the layer of the optical disc 6 is in focus, the control unit 39 determines whether or not the minute spot is focused on the target layer of the optical disc 6 based on the signal from the layer determination unit 37. If it is determined that the fine spot is focused on a layer other than the target of the optical disc 6, the control means 39 drives the actuator 7 to the actuator driving means 38 so as to quickly focus on the target layer. Control is performed so that they are adjusted again. As a result, a stable error signal can be obtained in the servo control performed on this recording layer in a short time, and data can be normally reproduced and recorded on the target layer of the optical disc 6. It becomes like this.

  In the optical disk apparatus according to the present embodiment, it is possible to detect that the focal point is focused on the layer other than the target by using the spherical aberration generated when the minute spot is mistakenly focused on the layer other than the target. There is an effect that the operation of refocusing the minute spot on the target layer can be performed.

In the present embodiment, the spherical aberration correction amount stored in the aberration correction amount storage means 31 can be determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control. An average value may be used. When the correction amount of the spherical aberration is determined in advance for each of a plurality of layers of the optical disc 6 that performs focus control, the correction amount is selected and switched according to the type of the disc and the target layer.
The spherical aberration correction amount stored in the aberration correction amount storage unit 31 may be the spherical aberration correction amount of the liquid crystal aberration correction element 4 when the optical disk apparatus is assembled and adjusted using the optical disk 6 having the reference thickness. You may set from the standard value of the base-material thickness of the optical disk 6. FIG.

  In this embodiment, every time the optical disk device is started, the value stored in the threshold storage unit 74 may be reset by the following method. In other words, the value stored in the threshold value storage means 74 is the jitter value of the signal detected by the RF signal jitter detection means 75 after the actuator 7 is driven by the actuator drive means 38 and a minute spot converges on an arbitrary layer. A value learned from the size may be reset as a threshold for an arbitrary layer. By correcting the threshold value by such a method, an error in the output from the RF signal jitter value comparison unit 76 due to the influence of a change in the RF signal with time or a temperature change can be minimized, and the determination result by the layer determination unit 37 It is possible to eliminate the error.

  In this embodiment, every time the optical disk device is started, the value stored in the threshold storage unit 74 may be reset by the following method. That is, the value stored in the threshold value storage means 74 sets the driving amount of the aberration correction element driving means 26 to the optimum driving amount for the target layer, and drives the actuator 7 by the actuator driving means 38 so as to be set to an arbitrary layer. The magnitude of the jitter value of the signal detected by the RF signal jitter detection means 75 after the minute spot has converged and the driving amount of the aberration correction element driving means 26 are set to an optimal driving amount other than the target layer, and any An intermediate value between the magnitude of the jitter value of the signal detected by the RF signal jitter detection means 75 after the minute spot has converged on this layer may be reset as a threshold for an arbitrary layer. By correcting the threshold value by such a method, an error in the output from the RF signal jitter value comparison unit 76 due to the influence of a change in the RF signal with time or a temperature change can be minimized, and the determination result by the layer determination unit 37 It is possible to eliminate the error.

  In an optical disc apparatus that records, reproduces, or erases information by accessing the optical recording medium, the focus can be drawn on the target layer, and it can be applied to various optical disc apparatuses that handle optical recording media having a plurality of information recording layers. Therefore, accurate recording, accurate reproduction, and reliable erasure can be realized, and improvement in reliability of recording and reproduction can be expected.

1 is a configuration diagram of an optical disc device according to a first embodiment of the present invention. Configuration diagram of optical disk apparatus according to Embodiment 2 of the present invention Configuration diagram of optical disk apparatus according to Embodiment 3 of the present invention Configuration diagram of optical disk apparatus according to Embodiment 4 of the present invention Configuration diagram of optical disk apparatus according to Embodiment 5 of the present invention Configuration diagram of optical disc apparatus according to Embodiment 6 of the present invention Configuration diagram of optical disc apparatus according to Embodiment 7 of the present invention Configuration diagram of an optical disc apparatus according to an eighth embodiment of the present invention Configuration diagram of optical disk apparatus according to Embodiment 9 of the present invention Configuration diagram of optical disk apparatus according to Embodiment 10 of the present invention Configuration diagram of optical disk apparatus according to Embodiment 11 of the present invention Waveform diagram of the playback signal and its amplitude when the target layer is detected and another layer different from the target is detected Waveform diagram of the playback signal and its maximum value when the target layer is detected and another layer is detected Configuration diagram of optical pickup Configuration diagram of a conventional optical disk device Configuration diagram of a conventional optical disc apparatus using means for correcting spherical aberration Cross section of a two-layer optical disc

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser light source 2 Diffraction element 3 Collimating lens 4 Liquid crystal aberration correction element 5 Objective lens 6 Optical disk 7 Actuator 8, 9 Photodetector 10 Light beam (laser light)
11 Optical pickup 12 Disc discrimination means 13 Disc discrimination signal 14 Aberration correction amount switching means 26 Aberration correction element driving means 31 Aberration correction amount storage means 32 Focus error detection means 33 Tracking error detection means 34 Threshold storage means 35 Tracking error signal amplitude detection means 36 Tracking error signal amplitude comparison means 37 Layer determination means 38 Actuator drive means 39 Control means 40 Threshold storage means 41 Tracking error signal level detection means 42 Tracking error signal level comparison means 44 Threshold storage means 45 Tracking error signal balance detection means 46 Tracking error Balance comparison means 48 Threshold storage means 49 Tracking error signal AGC detection means 50 Tracking error signal AGC value comparison means 51 Tracking error signal amplifier 60 addition signal generation means 61 threshold storage means 62 addition signal level detection means 63 addition signal level comparison means 66 threshold storage means 67 addition signal AGC detection means 69 addition signal AGC value comparison means 70 RF signal generation means 72 RF signal amplitude detection means 73 RF signal amplitude comparison means 74 Threshold storage means 75 RF signal jitter detection means 76 RF jitter value comparison means 77 Threshold storage means 78 RF signal level detection means 79 RF signal level comparison means 83 Threshold storage means 84 RF signal AGC detection means 85 RF signal AGC value comparison means 86 Threshold storage means 87 RF envelope signal detection means 88 RF envelope level comparison means

Claims (37)

An optical disk device for accessing an optical recording medium having a plurality of information recording layers,
Focus moving means for moving in the optical axis direction a condensing optical system that converges to a minute spot on the optical recording medium, and a photodetector that receives the light beam reflected by the optical recording medium and outputs an electrical signal according to the amount of light. An optical pickup having
A focus error detecting means for detecting a convergence state of the minute spot converged on the optical recording medium based on an output signal from the photodetector;
Actuator driving means for driving the focus moving means based on an output signal from the focus error detecting means to control the convergence state of the minute spots on the optical recording medium;
Tracking error detection means for detecting a relative deviation state between the minute spot converged on the optical recording medium and a track provided on the optical recording medium based on an output from the photodetector; ,
Tracking error signal amplitude detection means for detecting the amplitude of the tracking error signal based on the output from the tracking error detection means;
Tracking error signal amplitude comparing means for comparing the signal amplitude detected by the tracking error signal amplitude detecting means with a comparison reference value;
Threshold storage means for storing a comparison reference value to be given to the tracking error signal amplitude comparison means;
A layer determination unit that detects whether the minute spot has converged on a target layer or a layer other than the target from the output of the tracking error signal amplitude comparison unit;
An optical disc provided with control means for controlling the focus moving means by the actuator driving means based on an output from the layer determining means so that the minute spots converged on the optical recording medium converge on a target layer apparatus. The value stored in the threshold value storage unit is configured to be learned and corrected from the magnitude of the signal amplitude detected by the tracking error signal amplitude detection unit after the minute spot has converged on a target layer. The optical disk device described. The value stored in the threshold storage means is
The magnitude of the signal amplitude detected by the tracking error signal amplitude detecting means after the minute spot has converged on the target layer and the correction amount of the aberration correcting means for correcting the spherical aberration of the focusing optical system of the pickup are set as the target. 2. The optical disc apparatus according to claim 1, wherein the optical disc apparatus is configured to determine the amount based on a signal amplitude detected by the tracking error signal amplitude detection means when an optimum correction amount other than the layer is set. An optical disk device for accessing an optical recording medium having a plurality of information recording layers,
Focus moving means for moving in the optical axis direction a condensing optical system that converges to a minute spot on the optical recording medium, and a photodetector that receives the light beam reflected by the optical recording medium and outputs an electrical signal according to the amount of light. An optical pickup having
A focus error detecting means for detecting a convergence state of the minute spot converged on the optical recording medium based on an output signal from the photodetector;
Actuator driving means for driving the focus moving means based on an output signal from the focus error detecting means to control the convergence state of the minute spots on the optical recording medium;
Tracking error detection means for detecting a relative deviation state between the minute spot converged on the optical recording medium and a track provided on the optical recording medium based on an output from the photodetector; ,
Tracking error signal level detection means for detecting the level of the tracking error signal based on the output from the tracking error detection means;
Tracking error signal level comparison means for comparing the signal level detected by the tracking error signal level detection means with a comparison reference value;
Threshold storage means for storing a comparison reference value to be given to the tracking error signal level comparison means;
A layer determination unit that detects whether the minute spot has converged on a target layer or a layer other than the target from the output from the tracking error signal level comparison unit;
An optical disc provided with control means for controlling the focus moving means by the actuator driving means based on an output from the layer determining means so that the minute spots converged on the optical recording medium converge on a target layer apparatus. The optical disk according to claim 4, wherein the value stored in the threshold value storage means is corrected by learning from the signal level detected by the tracking error signal level detection means after the minute spot has converged on a target layer. apparatus. The value stored in the threshold value storage means is the signal level detected by the tracking error signal level detection means after the minute spot has converged on the target layer, and the aberration for correcting the spherical aberration of the focusing optical system of the pickup. 5. The optical disc apparatus according to claim 4, wherein the optical disc apparatus is configured to make a determination based on the signal level detected by the tracking error signal level detection means when the correction amount of the correction means is an optimum correction amount other than the target layer. An optical disk device for accessing an optical recording medium having a plurality of information recording layers,
Focus moving means for moving in the optical axis direction a condensing optical system that converges to a minute spot on the optical recording medium, and a photodetector that receives the light beam reflected by the optical recording medium and outputs an electrical signal according to the amount of light. An optical pickup having
A focus error detecting means for detecting a convergence state of the minute spot converged on the optical recording medium based on an output signal from the photodetector;
Actuator driving means for driving the focus moving means based on an output signal from the focus error detecting means to control the convergence state of the minute spots on the optical recording medium;
Tracking error detection means for detecting a relative deviation state between the minute spot converged on the optical recording medium and a track provided on the optical recording medium based on an output from the photodetector; ,
Tracking error signal balance value detection means for detecting a balance value of the tracking error signal based on an output from the tracking error detection means;
Tracking error signal balance value comparison means for comparing the magnitude of the signal balance value detected by the tracking error signal balance value detection means with a comparison reference value;
Threshold storage means for storing a comparison reference value to be given to the tracking error signal balance value comparison means;
Layer determination means for detecting whether the minute spot has converged on a target layer or a layer other than the target from the output of the tracking error signal balance value comparison means;
An optical disc provided with control means for controlling the focus moving means by the actuator driving means based on an output from the layer determining means so that the minute spots converged on the optical recording medium converge on a target layer apparatus. The value stored in the threshold value storage means is configured to learn and correct from the magnitude of the signal amplitude detected by the tracking error signal balance value detection means after the minute spot has converged on a target layer. 7. The optical disk device according to 7. The value stored in the threshold storage means is
The balance value detected by the tracking error signal balance value detecting means after the minute spot has converged on the target layer and the correction amount of the aberration correcting means for correcting the spherical aberration of the focusing optical system of the pickup are set as the target layer. 8. The optical disc apparatus according to claim 7, wherein the optical disc apparatus is configured to make a determination based on a balance value detected by the tracking error signal balance value detection means when an optimal correction amount other than the above is set. An optical disk device for accessing an optical recording medium having a plurality of information recording layers,
Focus moving means for moving in the optical axis direction a condensing optical system that converges to a minute spot on the optical recording medium, and a photodetector that receives the light beam reflected by the optical recording medium and outputs an electrical signal according to the amount of light. An optical pickup having
A focus error detecting means for detecting a convergence state of the minute spot converged on the optical recording medium based on an output signal from the photodetector;
Actuator driving means for driving the focus moving means based on an output signal from the focus error detecting means to control the convergence state of the minute spots on the optical recording medium;
Tracking error detection means for detecting a relative deviation state between the minute spot converged on the optical recording medium and a track provided on the optical recording medium based on an output from the photodetector; ,
Tracking error signal AGC detection means for detecting a deviation between the tracking error amplitude of the output from the tracking error detection means and the target amplitude;
Tracking error signal AGC value comparison means for comparing the magnitude of the control signal detected by the tracking error signal AGC detection means with a comparison reference value;
Threshold storage means for storing a comparison reference value to be given to the tracking error signal AGC value comparison means;
Layer determining means for detecting whether the minute spot has converged on a target layer or a layer other than the target from the output of the tracking error signal AGC value comparing means;
An optical disc provided with control means for controlling the focus moving means by the actuator driving means based on an output from the layer determining means so that the minute spots converged on the optical recording medium converge on a target layer apparatus. The optical disk according to claim 10, wherein the value stored in the threshold value storage means is corrected by learning from a control signal detected by the tracking error signal AGC detection means after the minute spot has converged on a target layer. apparatus. The value stored in the threshold value storage means is the control signal detected by the tracking error signal AGC detection means after the minute spot has converged on the target layer, and the aberration for correcting the spherical aberration of the focusing optical system of the pickup. 11. The optical disk apparatus according to claim 10, wherein the optical disk apparatus is configured to make a determination based on a control signal detected by the tracking error signal AGC detection means when the correction amount of the correction means is an optimum correction amount other than the target layer. An optical disk device for accessing an optical recording medium having a plurality of information recording layers,
Focus moving means for moving in the optical axis direction a condensing optical system that converges to a minute spot on the optical recording medium, and a photodetector that receives the light beam reflected by the optical recording medium and outputs an electrical signal according to the amount of light. An optical pickup having
A focus error detecting means for detecting a convergence state of the minute spot converged on the optical recording medium based on an output signal from the photodetector;
Actuator driving means for driving the focus moving means based on an output signal from the focus error detecting means to control the convergence state of the minute spots on the optical recording medium;
Addition signal generation means for generating a sum signal of the output from the photodetector;
Addition signal level detection means for detecting the level of the addition signal output from the addition signal generation means;
Addition signal level comparison means for comparing the signal level detected by the addition signal level detection means with a comparison reference value;
Threshold storage means for storing a comparison reference value to be given to the addition signal level comparison means;
A layer determining means for detecting whether the minute spot is converged on a target layer or a layer other than the target by an output from the addition signal level comparing means;
An optical disc provided with control means for controlling the focus moving means by the actuator driving means based on an output from the layer determining means so that the minute spots converged on the optical recording medium converge on a target layer apparatus. 14. The optical disc apparatus according to claim 13, wherein the value stored in the threshold value storage means is corrected by learning from a signal detected by the addition signal level detection means after the minute spot has converged on a target layer. Aberration correction for correcting the value stored in the threshold value storage means to correct the signal level detected by the addition signal level detection means after the minute spot has converged on the target layer and the spherical aberration of the focusing optical system of the pickup 14. The optical disc apparatus according to claim 13, wherein the optical disc apparatus is configured to make a determination based on the signal level detected by the addition signal level detection means when the correction amount of the means is an optimum correction amount other than the target layer. An optical disk device for accessing an optical recording medium having a plurality of information recording layers,
Focus moving means for moving in the optical axis direction a condensing optical system that converges to a minute spot on the optical recording medium, and a photodetector that receives the light beam reflected by the optical recording medium and outputs an electrical signal according to the amount of light. An optical pickup having
A focus error detecting means for detecting a convergence state of the minute spot converged on the optical recording medium based on an output signal from the photodetector;
Actuator driving means for driving the focus moving means based on an output signal from the focus error detecting means to control the convergence state of the minute spots on the optical recording medium;
Addition signal generation means for generating a sum signal of the output from the photodetector;
Addition signal AGC detection means for detecting a deviation between the output amplitude of the addition signal generation means and the target amplitude;
Addition signal AGC value comparison means for comparing the amplitude detected by the addition signal AGC detection means with a comparison reference value;
Threshold storage means for storing a comparison reference value to be given to the addition signal AGC value comparison means;
A layer determination unit for detecting whether the minute spot has converged on a target layer or a layer other than the target from the output of the addition signal AGC value comparison unit;
An optical disc provided with control means for controlling the focus moving means by the actuator driving means based on an output from the layer determining means so that the minute spots converged on the optical recording medium converge on a target layer apparatus. The optical disk apparatus according to claim 16, wherein the value stored in the threshold value storage means is corrected by learning from a signal detected by the addition signal AGC detection means after the minute spot has converged on a target layer. The value stored in the threshold value storage means is a signal level detected by the addition signal AGC detection means after the minute spot has converged on a target layer, and an aberration correction for correcting the spherical aberration of the condensing optical system of the pickup. 17. The optical disk apparatus according to claim 16, wherein the optical disk apparatus is configured to determine the correction amount based on the signal level detected by the addition signal AGC detection means when the correction amount of the means is an optimum correction amount other than the target layer. An optical disk device for accessing an optical recording medium having a plurality of information recording layers,
Focus moving means for moving in the optical axis direction a condensing optical system that converges to a minute spot on the optical recording medium, and a photodetector that receives the light beam reflected by the optical recording medium and outputs an electrical signal according to the amount of light. An optical pickup having
A focus error detecting means for detecting a convergence state of the minute spot converged on the optical recording medium based on an output signal from the photodetector;
Actuator driving means for driving the focus moving means based on an output signal from the focus error detecting means to control the convergence state of the minute spots on the optical recording medium;
RF signal generating means for extracting a reproduction signal generated based on the output from the photodetector;
RF signal amplitude detecting means for detecting the amplitude of the reproduction signal based on the output from the RF signal generating means;
RF signal amplitude comparison means for comparing the signal amplitude detected by the RF signal amplitude detection means with a comparison reference value;
Threshold storage means for storing a comparison reference value to be given to the RF signal amplitude comparison means;
A layer determination unit for detecting whether the minute spot has converged on a target layer or a layer other than the target from the output of the RF signal amplitude comparison unit;
An optical disc provided with control means for controlling the focus moving means by the actuator driving means based on an output from the layer determining means so that the minute spots converged on the optical recording medium converge on a target layer apparatus. 20. The optical disk apparatus according to claim 19, wherein the value stored in the threshold value storage means is corrected by learning from a signal detected by the RF signal amplitude detection means after the minute spot has converged on a target layer. Aberration correction means for correcting the value stored in the threshold value storage means, the amplitude detected by the RF signal amplitude detection means after the minute spot has converged on the target layer, and the spherical aberration of the focusing optical system of the pickup 20. The optical disc apparatus according to claim 19, wherein the correction amount is determined based on the amplitude detected by the RF signal amplitude detection means when an optimal correction amount other than the target layer is set. An optical disk device for accessing an optical recording medium having a plurality of information recording layers,
Focus moving means for moving in the optical axis direction a condensing optical system that converges to a minute spot on the optical recording medium, and a photodetector that receives the light beam reflected by the optical recording medium and outputs an electrical signal according to the amount of light. An optical pickup having
A focus error detecting means for detecting a convergence state of the minute spot converged on the optical recording medium based on an output signal from the photodetector;
Actuator driving means for driving the focus moving means based on an output signal from the focus error detecting means to control the convergence state of the minute spots on the optical recording medium;
RF signal generating means for extracting a reproduction signal generated based on the output from the photodetector;
RF signal level detection means for detecting the level of the reproduction signal based on the output from the RF signal generation means;
RF signal level comparison means for comparing the signal level detected by the RF signal level detection means with a comparison reference value;
Threshold storage means for storing a comparison reference value to be given to the RF signal level comparison means;
A layer determination unit for detecting whether the minute spot has converged on a target layer or a layer other than the target by an output from the RF signal level comparison unit;
An optical disc provided with control means for controlling the focus moving means by the actuator driving means based on an output from the layer determining means so that the minute spots converged on the optical recording medium converge on a target layer apparatus. The optical disk apparatus according to claim 22, wherein the value stored in the threshold value storage means is corrected by learning from a signal detected by the RF signal level detection means after the minute spot has converged on a target layer. Aberration correction for correcting the value stored in the threshold value storage means, the signal level detected by the RF signal level detection means after the minute spot has converged on the target layer, and the spherical aberration of the focusing optical system of the pickup 23. The optical disk apparatus according to claim 22, wherein the optical disk apparatus is configured to make a determination based on the signal level detected by the RF signal level detection means when the correction amount of the means is an optimum correction amount other than the target layer. An optical disk device for accessing an optical recording medium having a plurality of information recording layers,
Focus moving means for moving in the optical axis direction a condensing optical system that converges to a minute spot on the optical recording medium, and a photodetector that receives the light beam reflected by the optical recording medium and outputs an electrical signal according to the amount of light. An optical pickup having
A focus error detecting means for detecting a convergence state of the minute spot converged on the optical recording medium based on an output signal from the photodetector;
Actuator driving means for driving the focus moving means based on an output signal from the focus error detecting means to control the convergence state of the minute spots on the optical recording medium;
RF signal generating means for extracting a reproduction signal generated based on the output from the photodetector;
RF signal jitter detection means for detecting a jitter value of a reproduction signal based on an output from the RF signal generation means;
RF signal jitter value comparison means for comparing whether the magnitude of the jitter value detected by the RF signal jitter detection means is smaller than a predetermined jitter value;
Threshold storage means for storing a comparison reference value to be given to the RF signal jitter value comparison means;
A layer determination unit that detects whether the minute spot has converged on a target layer or a layer other than the target by an output from the RF signal jitter value comparison unit;
An optical disc provided with control means for controlling the focus moving means by the actuator driving means based on an output from the layer determining means so that the minute spots converged on the optical recording medium converge on a target layer apparatus. 26. The optical disk apparatus according to claim 25, wherein the value stored in the threshold value storage means is corrected by learning from a signal detected by the RF signal jitter detection means after the minute spot has converged on a target layer. Aberration correction for correcting the value stored in the threshold value storage means, the signal level detected by the RF signal jitter detection means after the minute spot has converged on the target layer, and the spherical aberration of the focusing optical system of the pickup 26. The optical disc apparatus according to claim 25, wherein the optical disc apparatus is configured to make a determination based on the signal level detected by the RF signal jitter detection means when the correction amount of the means is an optimum correction amount other than the target layer. An optical disk device for accessing an optical recording medium having a plurality of information recording layers,
Focus moving means for moving in the optical axis direction a condensing optical system that converges to a minute spot on the optical recording medium, and a photodetector that receives the light beam reflected by the optical recording medium and outputs an electrical signal according to the amount of light. An optical pickup having
A focus error detecting means for detecting a convergence state of the minute spot converged on the optical recording medium based on an output signal from the photodetector;
Actuator driving means for driving the focus moving means based on an output signal from the focus error detecting means to control the convergence state of the minute spots on the optical recording medium;
RF signal generating means for extracting a reproduction signal generated based on the output from the photodetector;
RF envelope signal detection means for detecting an envelope of a reproduction signal based on an output from the RF signal generation means;
RF envelope level comparison means for comparing the envelope value detected by the RF envelope signal detection means with a comparison reference value;
Threshold storage means for storing a comparison reference value to be given to the RF envelope level comparison means;
A layer determination unit for detecting whether the minute spot has converged on a target layer or a layer other than the target by an output from the RF envelope signal detection unit;
An optical disc provided with control means for controlling the focus moving means by the actuator driving means based on an output from the layer determining means so that the minute spots converged on the optical recording medium converge on a target layer apparatus. 29. The optical disc apparatus according to claim 28, wherein the value stored in the threshold value storage means is corrected by learning from a signal detected by the RF envelope signal detection means after the minute spot has converged on a target layer. The value stored in the threshold value storage means is the value detected by the RF envelope signal detection means after the minute spot has converged on the target layer, and the aberration correction means for correcting the spherical aberration of the focusing optical system of the pickup. 29. The optical disc apparatus according to claim 28, wherein the correction amount is determined based on a value detected by the RF envelope signal detection means when an optimal correction amount other than the target layer is set. An optical disk device for accessing an optical recording medium having a plurality of information recording layers,
Focus moving means for moving in the optical axis direction a condensing optical system that converges to a minute spot on the optical recording medium, and a photodetector that receives the light beam reflected by the optical recording medium and outputs an electrical signal according to the amount of light. An optical pickup having
A focus error detecting means for detecting a convergence state of the minute spot converged on the optical recording medium based on an output signal from the photodetector;
Actuator driving means for driving the focus moving means based on an output signal from the focus error detecting means to control the convergence state of the minute spots on the optical recording medium;
RF signal generating means for extracting a reproduction signal generated based on the output from the photodetector;
RF signal AGC detection means for detecting a deviation between the amplitude of the reproduction signal output from the RF signal generation means and the target amplitude;
RF signal AGC value comparison means for comparing the magnitude of the control signal detected by the RF signal AGC detection means with a comparison reference value;
Threshold storage means for storing a comparison reference value to be given to the RF signal AGC value comparison means;
A layer determination unit for detecting whether the minute spot has converged on a target layer or a layer other than the target by an output from the RF signal AGC value comparison unit;
An optical disc provided with control means for controlling the focus moving means by the actuator driving means based on an output from the layer determining means so that the minute spots converged on the optical recording medium converge on a target layer apparatus. 32. The optical disk apparatus according to claim 31, wherein the value stored in the threshold value storage means is corrected by learning from a signal detected by the RF signal AGC detection means after the minute spot has converged on a target layer. The value stored in the threshold value storage means, the value detected by the RF signal AGC detection means after the minute spot has converged on the target layer, and the aberration correction means for correcting the spherical aberration of the focusing optical system of the pickup 32. The optical disc apparatus according to claim 31, wherein the correction amount is determined on the basis of a value detected by the RF signal AGC detection means when an optimal correction amount other than the target layer is set. The optical disc apparatus according to any one of claims 3, 6, 9, 15, 18, 21, 21, 24, 27, 30, 33, wherein the aberration correction means is a liquid crystal phase shifter or an expander lens. Tracking error signal amplifying means for amplifying the tracking error amplitude of the output from the tracking error detecting means based on a control signal from the tracking error signal AGC detecting means is provided, and the output signal of the tracking error signal amplifying means is used as the control means. The optical disk apparatus according to claim 10, wherein the optical disk apparatus is input to the optical disk apparatus. Addition signal amplification means for amplifying the addition signal amplitude of the output from the addition signal generation means based on a control signal from the addition signal AGC detection means is provided, and an output signal of the addition signal amplification means is input to the control means The optical disk device according to claim 16. RF signal amplification means for amplifying the added signal amplitude of the output from the RF signal generation means based on a control signal from the RF signal AGC detection means is provided, and an output signal of the RF signal amplification means is input to the control means 32. The optical disc apparatus according to claim 31.

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