JP3456040B2 - Focus control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layered recording layer.
Multi-layer light such as magneto-optical recording type and pit recording type
Multi-layer optical data recording / reproducing recording data to / from disc
Disk recording device, multilayer optical disk reproducing device, multilayer optical disk
Suitable as a focus control system for disc recording and playback devices
Focus control device, especially during recording or playback
During recording or playback due to vibration during
The focus is shifted from the recording layer to another recording layer.
Detects debris removal and refocuses the original recording layer
1. Field of the Invention The present invention relates to a focus control device that performs a function or the like. 2. Description of the Related Art Conventional optical disks generally have a recording layer.
Is a single-layer optical disc having only one. Single-layer light
An optical disc playback device that plays back recorded data from a disc
When playback starts, the focus is first adjusted.
In order to perform this, the optical pickup
Drive the focus actuator. As a result,
The focal point of the beam changes near the focal point according to the above triangular wave.
Will move. Here, such focus movement control is performed.
When it comes to just focus, the sum signal (RF signal)
Above a certain level and the focus error signal is zero
It should be a level. For this reason, the above-mentioned optical disk reproducing apparatus is
The RF signal is detected and compared with a reference voltage of a predetermined level.
And a focus error signal is detected. So
Then, while the RF signal exceeds the level of the reference voltage,
Detecting the zero level of the focus error signal,
At the timing when the focus error signal becomes zero level,
Pull in the focus servo. Thus, the focus actuator
When the focus servo reaches the focal point, the focus servo
The focus error can be performed.
The recorded data can be reproduced while correcting the situation. [0006] Here, in recent years,
In order to increase the capacity of the optical disc, multiple recording layers
A multi-layer optical disc having a multi-layer structure as shown in FIG.
A disc 20 has been proposed. This multilayer optical disc 20
Is located between the transparent substrate 60 and the aluminum reflective layer 65, for example.
It is configured by laminating first to fourth recording layers 61 to 64.
You. The first to fourth recording layers 61 to 64 are optically
Are sequentially reduced, and the first and second recording layers
Between 61 and 62, between the second and third recording layers 62 and 63,
And between the third and fourth recording layers 63 and 64, respectively.
And transparent resin spacers 66 to 68 are provided. The recording data from such a multilayer optical disc 20 is
When reproducing data, focus on the desired recording layer.
In this case, the reproduction is carried out, but the desired recording layer is reproduced.
During life, for example, on discs, dirt, dust, scratches, etc.
Focus is applied from the desired recording layer by the impact
The recording layer other than the recording layer being reproduced.
No inconvenience of matching and playing back as it is
Can be considered. And out of focus like this
If this occurs, the original note that played the focus
It is necessary to match the recording layer. [0008] The present invention has been made in view of the above problems.
Focus during playback of multi-layer optical disc
If a disconnection occurs, it is detected and the
To match the original recording layer that was playing back earlier.
It is an object of the present invention to provide a focus control device that can be used. [0009] The focus according to the present invention.
The control device is a multi-layer optical disk comprising a plurality of recording layers stacked.
Focus control device that performs focus control on disks
And a file externally supplied by recording or reproduction.
The level of the focus error signal and the predetermined level of the reference signal
By comparing, the recording layer during recording or reproduction
Detect out-of-focus when another recording layer is in focus
Out-of-focus detection means, currently recording or reproducing
Recording layer detecting means for detecting a recording layer of the same, and recording layer detecting means
The recording layer currently being recorded or being reproduced is detected by
Storage means for storing the original recording layer information indicating
If the out-of-focus is detected by the
Read the original recording layer information from the storage
Data on the recording layer that has been recorded or reproduced due to misalignment
Record or playback due to out of focus
Detects the recording layer, generates the detection data, and
Focus jump by comparing with outgoing data
Generate recovery data indicating the number of layers to be
To perform recording or playback before out-of-focus occurs.
Focus to re-focus the recording layer
And control means for performing control. The focus control device according to the present invention includes a plurality of storage devices.
Focus on multi-layer optical discs with stacked recording layers
A focus control device for performing focus control.
The detachment detecting means is provided externally by the recording or reproduction.
Focus error signal supplied and reference signal of predetermined level
By comparing the level with
Out of focus when the focus is from one recording layer to another
Detect it. Further, a focus control device according to the present invention.
Indicates that the recording layer detecting means is currently recording or reproducing.
When a layer is detected, the storage means uses this as original recording layer information.
To remember. Then, the control means detects out-of-focus.
Storage means for detecting out-of-focus by the means
Read the original recording layer information from the
From the data of the recording layer recorded or reproduced by
The recording layer that has been recorded or reproduced due to defocus
Detects and generates detection data, and records the original recording layer information and detection data.
Layer to focus jump by comparing
Generated recovery data, and based on the recovery data,
Recording or playback was performed before out-of-focus occurred
Focus control to refocus the recording layer
Do. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a focus control device according to the present invention will be described.
Preferred embodiments will be described in detail with reference to the drawings.
You. [0015] Focus control apparatus according to an embodiment of the present invention
Is external during recording or playback as shown in FIG.
Focus error signal supplied from the
Input terminal 1 for the color signal and the input terminal 1
Focus based on the supplied focus error signal.
An out-of-focus detection circuit 3 for detecting out-of-focus
Is a recording layer designation unit 5 for designating a recording layer for recording.
have. Further, the above-mentioned focus control device includes
Original recording layer data indicating the recording layer specified by the recording layer specifying section 5
Out of focus with the memory 6a for storing data
Acceleration / deceleration to refocus the original recording layer in case
An acceleration / deceleration pulse generation circuit 7 for outputting a pulse;
Alternatively, the focus supplied through the input terminal 1 during reproduction
Error signal and acceleration / deceleration pulse from the acceleration / deceleration pulse generation circuit 7.
Switch 8 for switching and outputting the deceleration pulse
And the detection output from the out-of-focus detection circuit 3
Then, switching control of the changeover switch 8 is performed.
And a system controller 6. According to an embodiment having such a configuration,
The focus control device includes an optical disk reproducing device as shown in FIG.
Can be applied as the focus control unit 36
You. The operation of the optical disk reproducing apparatus will be described below.
The focus control device (for
The operation of the waste control unit 36) will be described. First, in FIG. 2, reproduction is started.
Then, a laser beam is emitted from the laser light source 21. This
Is collimated by the collimator lens 22
And enters the diffraction grating 23. The optical disk reproducing apparatus has a so-called three-track
The tracking error is now detected by the pot method.
ing. For this reason, the diffraction grating 23
The beam is divided into zero-order light and ± first-order light and emitted. This
The laser beam split into three beams is a polarizing beam splitter
24. The polarization beam splitter 24
The splitter film 24a transmits so-called P-polarized light.
S-polarized light having a polarization direction orthogonal to the P-polarized component
It has the property of reflecting component light. Laser Bee above
This polarization beam is
Most of the laser beam incident on the splitter 24 is
The light passes through the polarization beam splitter 24. This polarized beam
The laser beam transmitted through the splitter 24 has a quarter wavelength
The light is incident on the plate 25. The quarter-wave plate 25 is linearly polarized.
The laser beam of the P-polarized component, which is light, is circularly polarized.
Emit. This circularly polarized laser beam is
Focused by the lens 26 and irradiated onto the multilayer optical disc 20.
You. Next, laser recording is performed on the single-layer optical disc 20.
The reflected light is generated by the irradiation of the beam. This reflection
The light is transmitted to the 波長 wavelength plate 25 via the objective lens 26.
Incident, and a straight line of the S-polarized light component
The polarized light is incident on the polarization beam splitter 24.
You. As mentioned above, the polarizing beam splitter
24 polarization beam splitter film 24a
It has the property of reflecting light. Therefore, the polarization
Reflected light of the S-polarized light component incident on the beam splitter 24
Is reflected by the polarizing beam splitter 24 and is
Via the casing lens 27 and the collimator lens 28
The light is irradiated on the photodetector 29. The photo detector 29 is, for example, shown in FIG.
As shown in the figure, the first photodetector receives the reflected light of the zero-order light.
Detector 45 and ± 1 order reflected light
And second and third photodetectors 46 and 47.
ing. The first photodetector 45 has a
The light receiving area is divided into four equal parts radially around the optical axis (light receiving area
Region A to light receiving region D). In addition, the second and
The three photodetectors 46 and 47 are light receiving areas, respectively.
Is only one (light receiving area E and light receiving area F)
You. Each of the photodetectors 45 to 47 is
The amount of light corresponding to the amount of reflected light received in each light receiving area
Generates detection signals and uses them for tracking error detection.
30, focus error detector 31, and RF signal detector
32. The tracking error detecting section 30
Each light receiving area of the second and third photo detectors 46 and 47
The light amount detection signals from the areas E and F are respectively referred to as “E” and “F”.
As the tracking error signal based on the following formula
Is detected. Tracking error signal = E−F
The tracking error signal is output from the current / voltage conversion circuit (I /
(V conversion circuit) 33. The above I / V conversion circuit 3
3 is the tracking error supplied in the form of current.
-Convert the signal to a voltage, and use it for tracking driver 3
9. The tracking driver 39 is
Tracking coil 4 according to tracking error signal
Drive 0. Thus, the tracking error is corrected.
The objective lens 26 can be driven in
The recorded data can be reproduced in the state of the last track.
it can. Next, the focus error detecting section 31
Is the focus error, for example, by the so-called astigmatism method.
Is detected, and the first photo detail is detected.
Light amount detection signals from the light receiving areas A to D of the
Focuses on the basis of the following arithmetic expressions as "A to D", respectively.
Error signal is detected. Focus error signal = (A + D) − (B + C) The focus error signal detected by the focus error
The focus error signal is converted into a voltage by the I / V conversion circuit 34.
Is converted to the following through a focus control unit 36 described later.
To the focus driver 41. Above focus
The driver 41 responds to the focus error signal.
The focus coil 42 is driven. Thus, the focus error is corrected.
The objective lens 26 can be driven in the
Playback of recorded data can be performed in the state of strike focus.
it can. Next, the RF signal detection unit 32
Light from each light receiving area A to D of the first photodetector 45
Let the quantity detection signals be "A to D" respectively, and
Based on the detected RF signal. RF signal = A + B + C + D The RF signal detected by the RF signal detector 32
Is converted into a voltage by the I / V conversion circuit 35, and
The data is supplied to the data detector 37. The recording data detection unit 3
7 is, for example, a servo pattern based on the RF signal.
Only the recorded data from which the reproduced signal etc. of the
Through an output terminal 38 to a computer device or speaker device.
To an external device such as a device. Thus, the multi-layer optical disc 20
The reproduced recording data is recorded on another recording medium,
A sound output corresponding to the recorded data can be obtained, etc.
You. Here, the multi-layer optical disc 20 shown in FIG.
As shown in the figure, it is made of transparent material such as polycarbonate.
The transparent substrate 60 having a thickness of 1.16 to 1.2 mm
Example between aluminum reflective layer 65 formed of luminium
For example, it is configured by laminating first to fourth recording layers 61 to 64.
ing. The first to fourth recording layers 61 to 64 are respectively
The light transmittance is gradually reduced, and the first and second
Between the recording layers 61, 62, the second and third recording layers 62, 63
And between the third and fourth recording layers 63 and 64.
Transparent resin spacers 66 to 68 are provided, respectively.
You. The thickness of each of the spacers 66 to 68 is
If it is large, it adversely affects the imaging characteristics. Because of this,
The thickness of each spacer 66 to 68 depends on the imaging characteristics of the objective lens.
It must be within the range that can be compensated.
For example, the thickness is 35 to 40 μm. In addition,
Recording data is recorded in pits on the recording layers 61 to 64, respectively.
Has been recorded. Recording data is recorded from such a multilayer optical disc 20.
When playing back data, first,
It is necessary to focus on the recording layer. For this reason,
The user designates a recording layer to be reproduced by the recording layer designation section 5.
Set. The system controller 11 is used by a user.
When the desired recording layer is specified by the
Data in the memory 6a, and
Mode to focus on the specified recording layer.
I do. More specifically, the system controller 1
1 is the focus search mode
For example, a triangular wave signal of about 2 Hz is supplied to the coil 42.
To drive the objective lens 26,
The focus error signal
The error signal is compared with a predetermined reference signal. As mentioned above,
The multilayer optical disc 20 has four recording layers.
The focus error signal is compared with a predetermined reference signal.
By doing, four comparison pulses corresponding to the recording layer
Obtainable. The system controller 11 includes:
The number of pulses is counted, and the
After the comparison pulse of the recording layer is detected,
At the timing when the color signal becomes zero level.
Pull in the bo. Thus, focusing on the designated recording layer is performed.
The servo can be applied and the specified recording layer is recorded.
The recorded data can be reproduced. Next, the multi-layer optical disc 20 has four records.
Due to the recording layer, the disc playback device
Or discs have scratches or debris on the disc
Focus on recording layers other than the recording layer currently being played.
This causes inconveniences in reproducing recorded data.
Cause obstacles. For this reason, the disc reproducing apparatus is
In the focus control unit 36, the focus during reproduction is
Detects slippage. That is, during the reproduction, the focus
The focus error signal detected by the error detection unit 31
Signal is detected through the input terminal 1 shown in FIG.
The non-inverting input terminal of the first comparator 9 in the output circuit 3 and the second
Are supplied to the inverting input terminals of the comparator 11 respectively. The inverting input terminal of the first comparator 9 and the
The second comparator 11 has a non-inverting input terminal connected to the first base, respectively.
First reference voltage of predetermined level from reference voltage generating circuit 10
A predetermined level from the second reference voltage generation circuit 12
2 reference voltages are supplied. The first reference voltage has a defocused state.
If a focus error signal occurs, it can be detected.
And the second reference
The voltage is the focus error when out of focus occurs.
-The signal is set to a negative level that can detect the signal.
You. The first comparator 9 outputs the first reference voltage.
Pressure and a positive level focus error signal.
Supply the first comparison pulse to the system controller 6
I do. Further, the second comparator 11 is configured to output the second reference
Compare the voltage with the negative level focus error signal,
Is supplied to the system controller 6.
Pay. When the defocus occurs, the first
And the first and second comparison pulses from the second comparators 9 and 10
Should be supplied. For this reason, the system controller 6
Is detected by detecting the first and second comparison pulses.
Detects out-of-focus and focuses on the original recording layer.
Operation based on the flowchart shown in FIG. 4 to reset
I do. That is, this flowchart is the same as the above
Playback of recorded data recorded on the layer optical disc 20
It starts when it starts, and proceeds to step S1.
No. In step S1, the system controller
Supplied from the first and second comparators 9 and 11
Detecting the presence or absence of the first and second comparison pulses
Out-of-focus
If there is no focus, repeat step S1 to focus.
If a deviation has been detected, the process proceeds to step S2. Until the out-of-focus state is detected,
The system controller 6 is selected by the selection terminal 8c.
Toggle switch 8 to select terminal 8a
Control the focus error signal obtained during playback.
It is supplied to the focus driver 41,
When the debris is detected, in step S2,
Select so that the selected terminal 8b is selected by the selection terminal 8c.
Switching control of the switching switch 8 and playback.
Related parts to stop the output of recorded data
Control and proceeds to step S3. In step S3, the system controller
A recording layer stored in the memory 6a;
Readout of specified data and out of focus
After that, based on the reproduction data of the recording layer reproduced after
The recording layer reproduced by defocusing is detected. And
Playback due to the recording layer designation data and out of focus
And compares it with the data indicating the recording layer, and proceeds to step S4.
No. In step S4, the system controller
The controller 6 moves out of focus based on the comparison result.
To refocus the recording layer that was playing before
To adjust the focus, skip several layers.
Form recovery data that indicates whether
Proceed to step S5. In step S5, the system controller
The controller 6 determines whether or not the focus
Was playing before the out of focus occurred.
The focus is again adjusted on the recording layer, and the process proceeds to step S6. More specifically, for example, before defocusing,
The recording layer that was generated is the third recording layer 63,
The second recording layer 63 is in focus due to
If the system controller 6 is turned off,
(E) Low-level pulse shown from time t1 to time t7
Selects the selected terminal 8b with the selection terminal 8c.
Control of the changeover switch 8 as described above,
The high-level signals shown at times t1 to t3 in FIG.
The acceleration / deceleration pulse generation circuit 7 is controlled to generate a speed pulse.
I will. This acceleration pulse causes the changeover switch 8 to
The signal is supplied to the focus coil 42 through the control unit. This
The objective lens 26 is moved in the disk direction,
A focus error signal as shown in FIG.
You. The above-mentioned out-of-focus detection circuit 3 is shown in FIG.
As shown in (c), the focus error signal and the
1. Compare the second reference voltage. This allows the focus
While the error signal is at a level higher than the first reference voltage.
Is high as shown from time t2 to time t3 in FIG.
The level comparison pulse is supplied to the system controller 6.
Will be paid. The system controller 6 shown in FIG.
The falling of the comparison pulse shown at time t3 in FIG.
At this timing, it is detected at time t3 in FIG.
In order to stop the output of the acceleration pulse,
The deceleration pulse generation circuit 7 is controlled. The focusing coil 42 is provided with
The time t2 to the time t2 in FIG.
As can be seen from the focus error signal shown at t3,
The focus on the second recording layer 62 is temporarily out of focus.
And starts to fit the third recording layer 63, as shown in FIG.
As shown between time t3 and time t4, the focus error signal
Gradually becomes zero level.
Even after the supply of the acceleration pulse is stopped, the lens 26
Because the focus moves slightly due to inertia, etc.,
Negative focus error due to exceeding the focal point of the recording layer 63
Error signal is generated. The above-mentioned out-of-focus detection circuit 3 is shown in FIG.
As shown from time t4 to time t5 in FIG.
The level of the focus error signal is the level of the second reference voltage.
When it becomes less than or equal to the time shown in FIG.
Such a comparison pulse is formed, and this is
It is supplied to the roller 6. The system controller 6 is configured as shown in FIG.
The rising of the comparison pulse shown at time t4 in FIG.
At this timing, the time t4 to the time t4 in FIG.
To output a deceleration pulse as shown at t6 for a certain period of time
The acceleration / deceleration pulse generation circuit 7 is controlled. The output time of this deceleration pulse is
At the time of a scum jump, the focus once goes out of focus.
Is the time required to return to
Stipulated. As a result, the objective lens 26 is
In the disk direction, and once from the third recording layer 63
The out-of-focus is again focused on the third recording layer 63.
Then, the system controller 6 is configured as shown in FIG.
At time t6 shown, the output of the deceleration pulse is controlled to stop.
After that, at time t7 shown in FIG.
Is supplied to the changeover switch 8 and the selection terminal 8c
The focus jump is performed by selectively controlling the selected terminal 8a.
To end. In this example, the focus jump of one layer is used.
The focus jump was more than two layers.
When performing a focus jump, repeat the focus jump operation described above.
Return it and make it happen. The above-mentioned system controller 6
When the focus jump is completed, the process proceeds to step S6.
No. In the memory 6a, reproduction is performed before the focus is lost.
For example, address data of the recording layer
You. For this reason, the system controller 6 sets the
In step S6, based on the address data,
Detects the recording track that was playing before the focus went out of focus
And make a track jump to this recording track
By controlling the tracking driver 39 and the like shown in FIG.
Proceed to step S7. In step S7, the system controller
A recording layer before defocusing and a recording layer
Jump and track jump to the recording track
It is determined whether or not the pump has been completed.
Focus jump of step S5 and step S6 and
Control each part to repeat track jump,
In the case of YES, the process proceeds to step S8. In step S8, the system controller
The controller 6 restarts the output of the reproduced recorded data.
Control each part as shown in FIG.
Exit the routine. As described above, the focus control according to the present embodiment
The controller detects out-of-focus during playback and recovers it.
Can be old. Because of this,
The recorded data on the unintended recording layer
Can prevent inconveniences such as
A reproduction operation can be enabled. In the description of the above embodiment, the present invention
Such a focus control device is applied to an optical disc reproducing device.
This is, for example, an optical disc recording device or
Alternatively, the present invention may be applied to an optical disk recording / reproducing device. Also, the recording layer is designated by operating the recording layer designation section 5.
Recording layer designation data indicating the recorded recording layer is stored in the memory 6a.
When the focus is lost, this memory 6a
By reading the recording layer specification data from the
Detect the recording layer that was playing before the
However, this corresponds to the recording layer of the multilayer optical disc 20.
Each time, recording layer data indicating the recording layer is recorded,
The recording layer data obtained at the time of reproduction is stored in the memory 6a.
Detects the recording layer that was playing before the focus went out of focus
It may be. The optical disk 20 stores recorded data.
Is an optical disk preformed in a pit shape.
However, if this is a multi-layer structure, the
It is a matter of course that the optical disk may be used. The focus control device according to the present invention has the following features.
Focus from recording layer during recording or playback to another recording layer
When out of focus occurs,
Can be. The out-of-focus state is detected and the original
It is possible to refocus the recording layer.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a focus control device according to an embodiment of the present invention. FIG. 2 is a diagram showing a configuration of an optical pickup device provided with a focus control device according to the embodiment. FIG. 3 is a schematic diagram of a photodetector provided in the optical pickup device. FIG. 4 is a flowchart for explaining the operation of the focus control device according to the embodiment. FIG. 5 is a time chart for explaining a re-focusing operation of the focus control device according to the embodiment. FIG. 6 is a schematic diagram for explaining the structure of a multilayer optical disc. FIG. 7 is a diagram for explaining a state in which a focal point moves with respect to each recording layer of the multilayer optical disc. [Description of Signs] 1 Input terminal of focus error signal 3 Out-of-focus detection circuit 5 Recording layer designation unit 6 System controller 6a Memory 7 Acceleration / deceleration pulse generation circuit 8 Changeover switch 9 First comparator 11 Second comparator 10 1st reference voltage generating circuit 12 2nd reference voltage generating circuit 20 Multilayer optical discs 61-64 First to fourth recording layers

Claims (1)

(57) [Claim 1] A focus control device for performing focus control on a multi-layer optical disc having a plurality of recording layers laminated, wherein the focus is supplied from outside by the recording or reproduction. An out-of-focus detecting means for detecting an out-of-focus state in which a recording layer during recording or reproduction is focused on another recording layer by comparing the level of the error signal with a reference signal of a predetermined level; Recording layer detection means for detecting the recording layer of the following; storage means for storing the original recording layer information indicating the recording layer currently being recorded or being reproduced, detected by the recording layer detection means; and the out-of-focus detection means When the out-of-focus is detected, the original recording layer information is read from the storage means, and the recording or the recording is performed by the out-of-focus. Detecting the recording layer being recorded or reproduced due to the defocus from the data of the recording layer being reproduced, and detecting the detected data.
And compares the original recording layer information with the detection data.
The restoration data indicating the number of layers with focus jump
A control unit for generating focus data and performing focus control based on the restoration data so as to refocus the recording layer on which recording or reproduction was performed before the out-of-focus occurred.