JPH087382A - Optical information recorder - Google Patents

Abstract

PURPOSE:To stabilize the recording/reproduction by a method wherein the heating conditions in the leading end part of a data region are corrected and the leading end part and tail end part of a servo region are magnetized in required directions. CONSTITUTION:When data are recorded, preheat conditions, the clock phase compensation, etc., are given by recording compensation 1417 in accordance with the instruction of recording/reproduction condition control 1442 and a light pulse oscillation instruction is generated in accordance with the reference clock of a data system. A recording pulse is applied to an optical disc medium 10 by an optical head 1403 through a laser driver 1407 in accordance with the oscillation instruction. After an error code is added to recorded data from an interface 1427 by error correction 1426, the recorded data are modulated 1416 and applied to the medium 10 through recording compensation 1501, a magnetic head driver 1502 and a magnetic head 1500. At that time, in order to correct the heating conditions in the leading end part of a data region, several light pulse trains having the same conditions as in the data region are applied to the tail end part of a servo region.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device for recording or reproducing information by irradiating an information track recorded concentrically or spirally on a disk-shaped recording medium with convergent laser light.

[0002]

2. Description of the Related Art As a conventional recording system for a magneto-optical disk of a magneto-optical field modulation type, there is a recording system described in, for example, JP-A-1-292603. According to the present invention, a magnetic coil for generating a magnetic field near a track of a magneto-optical disk medium is used, the polarity of the magnetic field is made to correspond to the polarity of code data to be recorded, and the laser light is synchronized with the data recording clock frequency. Then, while continuously irradiating short pulses, the data is directly overwritten on the magneto-optical disk.
At this time, since laser pulses having the same period and the same pulse width are applied, the conditions of thermal diffusion and heat retention are almost the same regardless of the location, so the formed recording marks (magnetic domains) are tracked. It has the feature that it can be modulated in the length direction with the same width in the direction perpendicular to.
At this time, the shape of the recording mark is generally called a arrowhead shape.

[0003]

As described above, in order to keep the conditions of thermal diffusion and heat retention of the recording layer at the time of recording constant, it is necessary to constantly irradiate the recording film with a constant laser pulse. . However, in general optical discs, pre-formatted addresses, headers, servo information, etc. and data recording areas are alternately arranged along the tracks. Especially, in the optical disc of the sample servo system, the servo area and the data area are from several bytes. It has a segment structure in which it is alternately arranged at intervals of ten and several bytes, and the boundary area between the servo area and the data area frequently appears. The above-mentioned JP-A-1
In Japanese Patent Publication No. 292603, a recording method using such a sample servo system medium is described in FIG. 2. However, the recording laser pulse is not applied to the servo area but is applied only to the data area. Has become. FIG. 2 schematically shows the problems of the conventional recording method.
As shown in the figure, at the beginning of the data area, there is no recording laser pulse emitted before, so compared to other areas,
Since the temperature of the recording film is low, there is a problem that the recorded marks are small.

When the recording method of FIG. 2 is used,
Since the magnetic field is not applied to the servo area, the magnetization direction of the boundary area between the data area and the servo area may become indefinite due to the diffusion of thermal energy of the recording laser pulse applied to the data area. This causes noise when reproducing the information recorded at the beginning and end of the data area, which causes a reproduction error.

[0005]

In order to solve the above-mentioned problems, the present invention corrects the heating condition at the beginning of the data area and records the magnetization in a predetermined direction at the beginning and the end of the servo area. By doing so, the recording / playback is stabilized.

Specifically, in the servo area preceding the start of the data area, the recording layer is heated by irradiating an optical pulse for preheating, and a magnetic field is applied in a predetermined direction to change the magnetization direction of the recording layer. Provided is an optical disk device that solves the above problems by aligning in a fixed direction.

Further, the present invention can be applied to a phase change type optical disc other than the magneto-optical type. Since it is not necessary to apply external magnetization to the phase change type optical disk medium, the laser light for preheating is irradiated in the servo area, and the output is controlled to, for example, the crystallization level to control the thermal conditions in the data area. It is possible to provide an optical disk device which has a constant quality and which improves the quality of the reproduced signal at the beginning and end of the data area.

[0008]

According to the present invention, since the heating condition of the data area of the optical disk can be made constant during recording, the recording can be stabilized and the state of the recording layer in the boundary area between the data area and the servo area is always made constant. As a result, it is possible to prevent the quality of the reproduced signal from deteriorating.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a data recording method in an optical disk device of the present invention. In the figure, the vertical dotted line indicates the clock signal, and the optical pulse and the magnetic field are modulated based on the clock signal. In this embodiment, in order to correct the heating condition at the beginning of the data area, several optical pulse trains under the same conditions as those of the data area are applied to the end of the servo area. The number of laser pulses required to keep the thermal conditions constant is mainly determined by the film structure of the optical disc medium and the linear velocity of the rotating disc. Usually, by applying a few to a few dozen light pulses, the effect seen in the recorded signal can be made sufficiently small.

Further, in this embodiment, a magnetic field in a fixed direction is applied at the same time as irradiating a laser pulse to the end portion of the servo area, and the magnetization directions of the boundary area between the servo area and the data area are aligned in a fixed direction. As a result, it is possible to prevent the direction of magnetization from becoming indefinite in the boundary region, and it is possible to prevent the quality of the reproduced signal from deteriorating.

In this embodiment, the recording method at the beginning of the data area has been described. However, at the end of the data area, it is not necessary to record data thereafter, so the number of pulses to be applied is smaller than that at the beginning. be able to. However, in order to prevent the magnetization direction from becoming undefined in the boundary region, it is necessary to apply a magnetic field in a fixed direction for at least one bit.

The present invention can also be applied to other than the magnetic field modulation type magneto-optical disk described above. For example, it can be applied to a phase change type rewritable optical disk device. Since it is not necessary to apply external magnetization in the phase change type optical disk medium, the recording layer can be preheated by irradiating the servo area with laser light for preheating. At the same time, by keeping the output of the laser light at the crystallization level, for example, the state of the recording layer in the boundary area can be kept constant, and it is possible to prevent the quality deterioration of the reproduction signal at the beginning and end of the data area. become.

FIG. 3 shows another embodiment of the data recording method in the optical disk device of the present invention. In the embodiment of FIG. 1, it is necessary to irradiate a few to more than ten light pulses for preheating in the servo area, so it is necessary to secure a wider servo area by that amount. Since it is difficult to reproduce the prepits while irradiating the light pulse, it is necessary to irradiate the light pulse to an area where the prepits are not formed, which is generally called a mirror area. However, since the thermal characteristics differ depending on the film structure of the optical disc as described above, a sufficient preheating effect for the recording layer may not be obtained with only the mirror area of a predetermined format. For example,
In the 5.25 inch sample servo format (ISO-B format), there are only 3 channel bits from the clock pit to the beginning of the data area.

Therefore, in the embodiment shown in FIG. 3, the preheating is performed by the direct current laser light instead of the pulse. As a result, it is possible to reproduce the information of the pre-pit, and it is possible to secure a pre-heat area of a sufficient length regardless of the servo format. With this method, it is possible to treat the reproduced light as effectively increasing only during recording, so it is necessary to perform gain correction on the reproduced signal. Although a specific gain correction method will not be described here, similar gain correction has been conventionally performed for focus and tracking servo during recording, and is a known technique.

This method can also be applied to a phase change optical disk of the type that does not modulate the external magnetic field as in the above-mentioned embodiment.

FIG. 4 shows another embodiment of the data recording method in the optical disk device of the present invention. As described above, the sufficient preheating effect of the recording layer may not be obtained only with the mirror area. In the present embodiment, in order to correct the heating condition, the power of the light pulse at the beginning of the data area is set higher than the power of the light pulse at the center of the data area. The power of the i-th pulse from the beginning of the data area can be represented as Pi = P0-w1 * Pi-1-w2 * Pi-2 + ... Here, the coefficient wj (j = 1,2, ...
・) Indicates the temperature rise due to the heat effect from the optical pulse irradiated by j channel clocks before, and 0 <wj <
Satisfy 1. P0 is the initial value of the power of the optical pulse.
If the irradiation power is determined according to the equation (1), the optical power is large at the beginning of the data area and gradually approaches a constant value toward the center, as shown in FIG. The temperature can be constant.

According to this method, since preheating is not required in the servo area, accurate data can be recorded even on an optical disc medium whose mirror portion is not sufficiently long as described above.

FIG. 5 is an embodiment showing a method of setting the coefficient wj representing the magnitude of thermal interference. The coefficient wj can be determined in advance by recording a predetermined data pattern in a predetermined area by trial writing. In this embodiment, the recording condition is changed in a predetermined area to form an isolated mark of 1 channel bit, and the coefficient wj is set from the magnitude of the reproduced signal. As shown in the figure, the mark is formed by changing the number of light pulses of the same power P0 which are irradiated prior to the position where the isolated mark is formed. By doing so, the greater the number of preceding light pulses, the greater the effect of preheating and the larger the mark formed. Assuming that the temperature rise at the mark formation position when the number of preceding light pulses is j is Tj, T0 = αP0 T1 = T0 (1 + w1) T2 = T0 (1 + w1 + w2) T3 = It can be expressed as T0 (1 + w1 + w2 + w3). The magnitude Sj of the reproduced signal when the number of preceding light pulses is j can be approximated as follows by using the recording start temperature Tth and the constant β.

S0 = β (T0-Tth) S1 = β (T0 (1 + w1) -Tth) S2 = β (T0 (1 + w1 + w2) -Tth) S3 = β (T0 (1 + w1 + w2 + w3)- Tth) Therefore, the reproduction signal magnitudes S0, S1,
By measuring S2, S3, ..., the coefficient of thermal interference
w1, w2, w3, ... Can be defined as follows.

W1 = (S1-S0) / αβP0 w2 = (S2-S1) / αβP0 w3 = (S3-S2) / αβP0 Here, the constants α and β are determined by the structure of the optical disk medium and the linear velocity during recording. Therefore, it should be obtained in advance.

Here, as the simplest case, the method of obtaining the coefficient of thermal interference has been described in the case where a linear relationship is established between the magnitude of the reproduction signal, the temperature rise of the recording layer, and the power of the irradiation light pulse. , If the approximation accuracy is not sufficient, it is necessary to add a non-linear element. However, even in such a case, the function F can be expressed as wj = F (Sj-Sj-1, P0, v, ...) According to the idea of trial writing shown here. Here, v represents the linear velocity. The function F may be determined in advance as a recording characteristic of the optical disc medium at the time of shipment of the apparatus or may be determined by trial writing before recording.

This method can also be applied to a phase change optical disk of the type that does not modulate the external magnetic field as in the above-mentioned embodiment.

FIG. 6 shows an embodiment of a data recording method at the rear end of the data area in the optical disk device of the present invention. In the figure, the vertical dotted line indicates the clock signal, and the optical pulse and the magnetic field are modulated based on the clock signal in FIG.
This is the same as the embodiment. Preheating is basically unnecessary because it is not necessary to record any more data at the rear end of the data area. It may be considered to align the directions of magnetization in one direction. In FIG. 6, two bits are recorded in the initialization direction at the tip of the servo area. The required number of bits can be determined based on the condition that at least the recording must be performed in the initialization direction in the area covered by the skirt of the light spot when the last end of the data area is reproduced by the light spot. Normally, the length is about the track pitch (1-1.6μ
m) is necessary.

This method can also be applied to a phase change optical disk of the type that does not modulate the external magnetic field as in the above-mentioned embodiment.

FIG. 7 is an embodiment showing the structure of the optical disk device of the present invention corresponding to the magneto-optical disk of the magneto-optical field modulation type. Here, using the sample servo method, ZCAV is used.
(Zoned Constant Angular V
2 shows an apparatus for recording / reproducing by the “ecology” method. In the ZCAV method, since the rotation speed of the optical disk medium is constant, access is fast, and the linear density of recorded information becomes substantially constant for each zone, so that the information recording surface of the disk can be effectively used to increase the recording capacity.

On the other hand, in the sample servo system, which is one of the servo systems, data, focus error and tracking error are detected by time division based on the reference clock, so that the structure of the optical system is simple. This is advantageous for downsizing the device.

In the present invention, a PLL for generating a reference clock
The (Phase Locked Loop) circuit is divided into two systems for servo and data. A servo mark including a clock and wobble pits that are pre-formatted on an optical disc medium is a CAV (Constant Angular).
Similar to the ar Velocity) method, they are arranged radially. The servo PLL has a constant frequency in order to reproduce the servo mark and generate the focus and tracking error signals. The data PLL is set so that the recording density is substantially constant on the inner and outer circumferences of the optical disk medium, and the frequency increases substantially in proportion to the radius of the optical disk medium.

As a result, the servo system and the data recording / reproducing system become independent, and it becomes possible to record / reproduce the data in the ZCAV mode on the optical disk medium preformatted by the CAV system. .

In this case, the signal recorded on the optical disk medium has a large capacity per segment from the inner circumference to the outer circumference. For example, if information of N bytes per segment is recorded in the innermost zone and the whole is divided into m zones, the number of data bytes per segment increases by 1 byte from the inner periphery to the outer periphery. N in the outer zone
It can be + m-1. In this system, the servo clock and data clock can be set independently, so ZCAV
One of the features is that it can be used for both system data recording and CAV system data recording.

Next, the structure and operation of a specific device will be described. The rotation speed of the optical disk medium 10 is determined by the rotation speed control unit 1405.
The spindle motor 1402 is controlled by and is kept at a predetermined value. A laser driver 1407 turns on a semiconductor laser, which is a light source of the optical head 1403, and outputs a laser beam to the optical disc medium 10.
Irradiate on. The reflected light from the optical disc medium 10 is converted into an electric signal by a photodetector in the optical head 1403, amplified by a preamplifier 1408, and the recorded information on the optical disc medium is reproduced as a reproduction signal. The reproduction signal includes a reproduction signal of the pre-pit, a focus error signal, and a magneto-optical signal. Next, extract pits from the pre-pit playback signal 14
The clock pit signal is extracted by 13 and the servo system PL is used.
A servo system reference clock is generated by L1419. In the servo system PLL 1419, the frequency division ratio in the feedback loop is fixed so that a reference clock having a constant frequency is generated. The servo error signal and the address information can be detected based on the servo system reference clock.

Servo error detection is performed by servo error detection 1411 from the focus error signal amplified by the preamplifier 1408 and the prepit reproduction signal, and focus deviation and tracking deviation information is detected. Address information is detected from the prepit reproduction signal.
1412 and the information is passed to the address management 1443 in the controller 1440. For controller 1418,
The focus and tracking of the optical head 1403 are controlled via the mechanism driver 1409 so as to eliminate the scrap deviation and the tracking deviation, and the course actuator 1404 is operated as necessary to perform the seek control.

On the other hand, the data system reference clock is generated by the data system PLL 1420 from the reproduction signal of the pre-pit, and the data recording / reproduction is performed with reference to this.
The oscillation frequency of the data system PLL 1420 changes for each zone so that the recording density of the data becomes substantially constant. Therefore, the frequency division ratio in the data system PLL 1420 is set to each zone. The recorded data is reproduced as follows. The data signal extracted from the magneto-optical signal by the data detection 1415 is demodulated by the demodulator 1421, subjected to error correction processing by the error correction 1426 and reproduced as data, and externally transmitted via the interface 1427. The recorded data of is delivered.

When recording data, the recording compensation 1417 performs preheat conditions and clock phase compensation in accordance with the command of the recording / reproducing condition management 1442, and the optical pulse oscillation command is generated based on the data system reference clock. Is generated. By this oscillation command, a recording pulse is emitted from the optical head 1403 to the optical disc medium 10 via the laser driver 1407. On the other hand, the recording data fetched from the outside via the interface 1427 is added with an error code by the error correction 1426 and then modulated by the modulator 1416. Furthermore, clock phase compensation or the like is performed in the recording compensation 1501 according to the command of the recording / reproducing condition management 1442, and the magnetic head 1500 applies the magnetic field corresponding to the recording data to the optical disc medium 10 via the magnetic head driver 1502. Further, data is recorded at a predetermined position by designating an address to be recorded by the address management 1443.

FIG. 8 is an embodiment showing the structure of the optical disk device of the present invention corresponding to an optical disk medium capable of recording data by light intensity modulation such as phase change. The operation is the same as the above-described optical disk device corresponding to the optical magnetic field modulation type optical disk, except for the data recording process. In the case of recording data, the recording data fetched from the outside through the interface 1427 is added with an error code by the error correction 1426 and then modulated by the modulator 1416.
The recording compensation 1417 performs preheat conditions and clock phase compensation according to the command of the recording / playback condition management 1442 based on the data modulated by the modulator 1416, and oscillates the optical pulse based on the reference clock of the data system. To generate. This oscillation command causes the optical head 1403 to pass through the laser driver 1407.
The intensity-modulated laser light is applied to the optical disk medium 10. Since the recorded data can be read as the intensity change of the reproduction signal in the phase change type optical disk, the detection system of the magneto-optical signal is unnecessary, and the reproduction signal of the prepit described in the above embodiment is used as it is to reproduce the recorded data. You can also However, the amplitude of the phase change signal is generally smaller than the amplitude of the pre-pit signal, but it is desirable to reproduce as a signal of another system in which the gain of the pre-amplifier is changed. When a light modulation type magneto-optical disk is used as the optical disk medium, it is necessary to provide a magnetic head for applying a DC magnetic field to the optical disk medium. This type of magnetic field applying means is implemented in a commercially available magneto-optical disk device, and is not particularly shown in this embodiment. Further, it is natural that it is necessary to use the magneto-optical signal as the data signal.

[0036]

As described above, according to the present invention, stable data recording can be realized by performing preheating on a sample servo type optical disk.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of one embodiment showing a recording method of an optical disc device of the present invention.

FIG. 2 is an explanatory diagram showing a recording method of a conventional optical disc device.

FIG. 3 is an explanatory view of another embodiment showing the recording method of the optical disk device of the present invention.

FIG. 4 is an explanatory diagram of another embodiment showing the recording method of the optical disk device of the present invention.

FIG. 5 is an explanatory view of an embodiment showing a trial writing method of the optical disk device of the present invention.

FIG. 6 is an explanatory view of another embodiment showing the recording method of the optical disk device of the present invention.

FIG. 7 is a block diagram of an embodiment showing the configuration of the optical disk device of the present invention.

FIG. 8 is a block diagram of another embodiment showing the configuration of the optical disk device of the present invention.

[Explanation of symbols]

10 ... Optical disk medium, 1402 ... Spindle motor, 1403 ...
Optical head, 1404 ... Coarse actuator, 1405 ... Rotation speed control unit, 1407 ... Laser driver, 1408 ... Preamplifier, 14
09 ... Mechanism driver, 1411 ... Servo error, 1412 ... Address detection, 1413 ... Pit extraction, 1415 ... Data detection, 1416 ...
Modulator, 1417 ... Recording compensation, 1418 ... Controller, 1419 ... Servo system PLL, 1420 ... Data system PLL, 1421 ... Demodulator, 1426
... error correction, 1427 ... interface, 1440 ... controller, 1442 ... recording / playback condition management, 1443 ... address management, 1500 ... magnetic head, 1501 ... recording compensation, 1502 ... magnetic head driver.

Claims (7)

[Claims] 1. A clock signal is generated based on the timing of a reproduction signal from a pre-formatted pre-pit in an information recording layer of an optical information recording medium, and data recording of the optical information recording medium is performed based on the clock signal. An optical information recording device for recording information by irradiating an area with a laser pulse to heat the information recording layer, wherein the heating condition of the information recording layer at the head of the data recording area is the data area. An optical information recording device, comprising: a heating condition correcting means that is substantially equal to the heating condition of the information recording layer in the central part of the above. 2. A clock signal is generated based on the timing of a reproduction signal from a preformatted pre-pit of an information recording layer of an optical information recording medium, and data recording of the optical information recording medium is performed based on the clock signal. An optical information recording device for recording information by irradiating an area with a laser pulse to heat the information recording layer, wherein an area preceding a start end of the data recording area and an end of the data recording area during data recording At least 1 in the area following
An optical information recording device having a function of recording "0" or "1" of more than one bit. 3. The optical information recording apparatus according to claim 1, wherein the heating condition correcting means is a laser beam irradiation to an area preceding the data recording area of the optical information recording medium. Optical information recording device. 4. The optical information recording apparatus according to claim 1, wherein the heating condition correcting means sets the intensity of the laser pulse at the head portion of the data recording area of the optical information recording medium to the central portion of the data recording area. An optical information recording device, characterized in that the intensity is made higher than the laser pulse intensity. 5. A first means for applying a magnetic field having a polarity corresponding to the data to be recorded on the optical information recording medium, and a reproduction signal from a pre-pit pre-formatted on the information recording layer of the optical information recording medium. Is an optical information recording apparatus having a second means for heating the information recording layer by irradiating the optical information recording medium with a laser pulse having a constant frequency in synchronization with a clock signal generated based on the timing. A magnetic field having a constant polarity in the information recording layer is applied to the area preceding the data recording area of the optical information recording medium by the first means, and at the same time a laser pulse having a constant frequency is applied by the second means. An optical information recording device, which is characterized by irradiating a laser beam. 6. A first means for applying a magnetic field having a polarity corresponding to data to be recorded on an optical information recording medium, and a reproduction signal from a prepit pre-formatted on an information recording layer of the optical information recording medium. Is an optical information recording apparatus having a second means for heating the information recording layer by irradiating the optical information recording medium with a laser pulse having a constant frequency in synchronization with a clock signal generated based on the timing. Then, a magnetic field having a polarity in the initialization direction of the information recording layer is applied to the area preceding the data recording area of the optical information recording medium by the first means, and the direct current laser light is simultaneously irradiated. Optical information recording device. 7. A first means for applying a magnetic field having a polarity corresponding to data to be recorded on an optical information recording medium, and a reproduction signal from a pre-pit pre-formatted on an information recording layer of the optical information recording medium. Is an optical information recording apparatus having a second means for heating the information recording layer by irradiating the optical information recording medium with a laser pulse having a constant frequency in synchronization with a clock signal generated based on the timing. At the time of data recording, at least one bit of "0" or "1" is recorded by applying a laser pulse and a magnetic field to a region preceding the start end of the data recording region and a region following the end of the data recording region. An optical information recording device having a function.