JP2594993B2 - Magneto-optical signal recording / reproducing method and optical disk device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording / reproducing apparatus, and more particularly, to a method of reproducing a recording domain misalignment caused by overwriting by magnetic field modulation using a sample servo method during reproduction. The present invention relates to a magneto-optical signal recording / reproducing method suitable for performing accurate data demodulation by correction.

[Conventional technology]

Magneto-optical disks are attracting attention as optical disks on which information can be rewritten. The magneto-optical disk uses a perpendicular magnetization film as a recording film, forms a recording domain by a thermomagnetic effect, and obtains a reproduction signal by a magneto-optical effect. At the time of recording, the temperature of the magnetized film is raised to the Curie temperature by the heat of the laser light spot to lose the magnetization, and the perpendicular magnetization is fixed in the direction of the external magnetic field during the cooling process. In order to form a magnetization domain, an external magnetic field is applied by applying a constant intensity magnetic field in the direction opposite to the initial magnetization direction of the perpendicular magnetization film, and the intensity of the laser light pulse is changed according to the data. Conversely, there is a magnetic field modulation method in which the laser light intensity is set to a constant value so that the temperature of the magnetized film is equal to or higher than the Curie temperature, and the direction of the external magnetic field is changed according to the data.

In the light modulation method, it is not necessary to switch the external magnetic field at a high speed, so that an electromagnetic coil or a magnet for applying the magnetic field can be installed away from the disk surface. Further, the shape of the formed magnetic domain can be a circle or an ellipse relatively faithful to the light spot distribution. However, it is difficult to realize the overwriting performed on the magnetic disk, that is, the operation of recording new data and the operation of simultaneously erasing old data, with a one-beam optical head. It is necessary to perform the erasing operation in the circumference and perform the recording operation in the next one round. In response to a request for overwriting, it is necessary to use a plurality of two-beam light heads or a plurality of one-beam light heads.

On the other hand, in the magnetic field modulation method, it is necessary to switch an external magnetic field at a high speed, so that an electromagnetic coil having a large inductance has a large time constant and is difficult to use. Therefore, an electromagnetic coil having a relatively small inductance is used, but the generated magnetic field strength when driven with the same current value is smaller than a coil having a large inductance. Therefore, it is necessary to install the device close to the disk surface. In the case of an optical disk, the target for recording and erasing is only the portion irradiated with the optical spot, so the gap between the disk and the magnetic head is smaller than that of the magnetic disk.
It can be as wide as one or two digits. It is known that the shape of the formed magnetic domain does not always coincide with the light spot distribution, and generally has a wedge shape. The reason is that even if the optical spot is irradiated, the domain formation is stopped when the applied magnetic field is turned off.Therefore, the top of the domain has an outwardly convex circular shape according to the optical spot distribution, but the rear end of the domain is This is because it becomes an inwardly convex circle. On the other hand, overwriting can be realized by a single magnetic head and an optical head as in the case of a magnetic disk.

In the case of the magnetic field modulation method, one of the problematic items is
The section where the recording magnetic field is applied does not coincide with the section of the magnetization domain to be formed. This is because recording or erasing depends not on the light spot distribution itself but on the temperature distribution of the recording film. Due to the balance between the thermal conductivity of the recording film and the linear velocity at the time of recording, a peak value of the temperature distribution appears behind the position of a general optical spot. Therefore, since the recording is performed at a location where the temperature of the recording film is equal to or higher than the Curie temperature, a domain is formed with a time delay from the application start time of the recording magnetic field. On the other hand, when the information is read, the information is reproduced earlier in time.
If a data modulation method having a self-clocking property, for example, an MFM (Modified FM) or RLL (Run-Length Limit) system is used, this shift in recording timing is uniform in each recording domain. If there is, using the read clock generated from the data string, the shift between the recording data patterns hardly causes a problem. However, the clock for data demodulation,
In the case of using a magnetic field modulation method in a sample format system obtained from a previously provided pit, when a recording magnetic field is applied using the clock at the time of recording, the timing between the recording domain and the clock at the time of reproduction for the reasons described above. May be shifted. In particular, when NRZ (non-return to zero) modulation or the like having no self-clocking property is used as the data modulation method, it is not possible to obtain reproduction clock information from the data itself, so that accurate demodulation cannot be performed.

As described above, when the magnetic field modulation method is applied to the sample format system, it is important to correct the recording timing deviation by some means.

Japanese Patent Application Laid-Open (JP-A) No. 54-95250 relates to a magneto-optical disk device that realizes overwriting by a magnetic field modulation method. In this device, the laser beam is continuously applied for raising the recording film temperature,
An electromagnet provided around the objective lens of the optical head is driven in accordance with data to realize recording and erasing. In this apparatus, the above-described recording timing shift and
No correction means is mentioned.

[Problems to be solved by the invention]

The above prior art does not mention the positional deviation between the position where the recording magnetic field is applied and the magnetization domain to be formed, and the case where a modulation system without self-clocking property is realized by a sample format system or the case where recording / reproducing is performed. However, there is a problem that it is difficult to apply the method for generating and generating data from a pit string provided in advance and performing data modulation and demodulation.

An object of the present invention is to correct a positional deviation between an application position of a recording magnetic field and a formed magnetic domain during data reproduction,
It is an object of the present invention to provide a magneto-optical disk device based on a magnetic field modulation system for realizing accurate demodulation.

[Means for solving the problem]

The above object is to form a reference domain for generating and synchronizing a reproduction clock at the beginning of a data pattern at the time of recording, and to demodulate the data by the reproduction clock generated from the reference domain at the time of data reproduction. Is achieved by

Further, this is achieved by using only the phase of the recording clock selected by the signal obtained from the reference domain as the reproducing clock.

[Action]

The reference domain for generating the reproduction clock is recorded immediately after the pre-pit in the sample format system, and then the user data pattern is recorded. At the time of recording, a magnetization domain is formed by a clock generated from a prepit, and at the time of reproduction, data is generated by using a clock (phase lock loop) generated by a PLL (phase lock loop) circuit based on the reference domain. Perform demodulation.

By the above processing, even if a recording timing shift occurs, the reproduction clock is generated by the reference domain, so that the timing shift between the reproduction clock and the recorded data pattern hardly occurs, and accurate data demodulation is performed. Can be realized. Also, a method of changing only the phase of the recording clock and using it as a reproduction clock can correct the timing deviation at the time of recording.

〔Example〕

Hereinafter, an embodiment of the present invention will be described. FIG. 1 is a diagram showing a configuration example of a magneto-optical disk recording / reproducing apparatus for carrying out the present invention. The disk 1 is a magneto-optical disk having a perpendicular magnetization film mainly composed of, for example, a TeFeCa element, and is a sample format disk in which pits for tracking and recording clock generation have been prepared in advance. An example of the arrangement of the pits will be described later. The disk 1 can be rotated by a spindle motor 2.

Recording of data on the disk 1 is performed as follows. The semiconductor laser 3 is caused to emit light with high power by the laser drive circuit 4. At the time of data reproduction, the laser drive circuit 4 receives recorded data,
That is, the semiconductor laser 3 emits light at a low power so as not to affect the magnetization domain. At the time of data recording, the temperature of the recording film is raised to a key temperature at which the magnetization reversal of the recording film is enabled by the magnetic field generated by the magnetic head 5. It has the function of causing the semiconductor laser 3 to emit light with high power in order to raise it. The configuration of the laser drive circuit 4 may be a circuit used in a conventional write-once optical disk device. Unlike the optical modulation method, the laser drive circuit 4 emits the semiconductor laser 3 at a constant high power regardless of recording data during recording. Do it. Further, since it is not necessary to perform light modulation at the time of recording, an element or a circuit configuration having a low comparison base switching speed can be used.

Now, the light beam of the semiconductor laser 3 is collimated by the lens 6 and then passes through the beam splitter 7 to the galvanomirror 8.
Is reflected vertically upward, and is condensed by the aperture lens 9 on the recording film of the disc 1 as a minute spot having a diameter of about 1 μm. When the temperature of the perpendicular magnetization film is raised by the heat of the condensing spot, a modulation magnetic field is applied by the magnetic head 5 to record data, that is, to form a magnetization domain. As described above, in the case of recording, the temperature of the perpendicular magnetic film rises to the temperature equal to or higher than the Curie temperature in the portion irradiated with the light spot, so that the data overwriting, that is, the recording operation was performed in the same manner as the magnetic disk. It is possible to perform recording that also serves as erasure of data recorded in the. Magnetic head 5
Are arranged so as to slightly float from the surface of the disk 1 as in the case of the magnetic disk. However, the distance between the magnetic head 5 and the disk 1 may be several tens of microns, which is wider than that of a magnetic disk having no auxiliary means such as an optical spot, and the problem of the head crash is less likely to occur. . Magnetic head drive circuit 10
Has a function of changing the direction of the magnetic field generated by the magnetic head 5 in accordance with the modulated recording data.

Next, reproduction of data recorded on the disc 1 will be described. The laser drive circuit 4 causes the semiconductor laser 3 to emit light at low power in accordance with a command from the recording / reproduction control system. The polarization plane of the light of the semiconductor laser 3 is in a certain direction, and this light is applied to the perpendicular magnetization film on the disk 1 through the same optical path as during recording. The magnetization direction of the perpendicular magnetization film is fixed upward or downward according to the recorded data. By detecting whether the magnetization direction is up or down, 1,0 of the recorded data is determined. This detection is performed using the Kerr effect, which is one of the magneto-optical effects. The Kerr effect is an effect in which the plane of polarization of incident light rotates left or right with respect to the original plane of polarization depending on whether the magnetization direction is upward or downward. The reflected light from the perpendicular magnetization film accompanied by the rotation of the polarization plane is reflected again by the beam splitter 7 and the beam splitter 11, and is guided to the half-wave plate 12. The half-wave plate 12 is an optical element having a function of rotating the polarization plane by 45 degrees. The light whose polarization plane is rotated by 45 degrees is separated into a p-polarized light component and an S-polarized light component by a polarizing beam splitter 13 and condensed on photodetectors 16 and 17 by lenses 14 and 15, respectively. By taking the sum of the outputs of the photodetectors 16 and 17, it is possible to detect only a change in light intensity regardless of the polarization plane rotation. Further, if the difference between the outputs of the photodetectors 16 and 17 is obtained, a change in the magnetization direction can be detected as a signal change through rotation of the polarization plane. That is, the sum signal 18 is optically separated from only the uneven pits previously provided on the disk 1, and the difference signal 19 is from the change in the magnetization direction of the perpendicular magnetization film on the disk 1, that is, only the recorded data. Can be detected.

This detection principle will be described with reference to FIG. FIG. 2A shows the polarization direction of the emitted laser light. The polarization components are all P-polarization components. FIG. 2B shows the polarization direction of the reflected light from the perpendicular magnetization film. The plane of polarization rotates by Kerr rotation angles + θ _k , −θ _k depending on whether the magnetization direction is upward or downward. FIG. 2 (c) shows 1 /
2 shows the polarization direction of light that has passed through the two-wavelength plate 12. The principal axis direction of the plane of polarization rotates by 45 degrees. The polarization beam splitter 13 has a property of transmitting nearly 100% of the p-polarized light component and reflecting nearly 100% of the s-polarized light component. Therefore, photodetector 1
6 detects a change 101 in the amount of light on the p-polarization axis in FIG. 2C, and the photodetector 17 detects a change 102 in the amount of light on the s-polarization axis. Now, the rotation of the polarization plane changes from + θ _k to −θ _k
Considering the case where the light amount has changed, the signal light amount detected by the photodetector 16 changes from a small state to a large state, and conversely, the signal light amount detected by the photodetector 17 changes from a large state to a small state. Therefore, if the sum signal of the two is taken, the rotation of the polarization plane due to the change in the magnetization direction is canceled out, so that only the change in the amount of reflected light due to the uneven pits can be detected without detecting the magneto-optical signal. it can. On the other hand, if the difference signal between the two is obtained, the magneto-optical signal can be detected as the sum of the light quantity changes 101 and 102.

Next, the format of the disk 1 used in the configuration example of FIG. 1 will be described. FIG. 3 is an enlarged view of a part of the disk 1. When performing master cutting in advance, virtual tracks 110 to 118 are formed on disk 1.
It is created alternately with right and left deviations from 120 to 122. The pits 110-118 are used to track optical spots 120-1.
22.Tracking control for moving along any one of 22 and PL
It is input to an L (phase lock loop) circuit and used to generate a clock when data is recorded.
The tracks 120 to 122 are provided on the disk 1 concentrically or spirally. Data is recorded in an area between the pits 110 to 118, for example, an area 130.

In the configuration example of FIG. 1, the tracking control system is omitted, but actually, it is performed as follows. The signal level of the sum signal 18 varies depending on which part of the pits 110-118 the optical spot passes through. That is, the signal change is largest when passing directly above the pit, and the signal change is small when passing the end of the pit. Therefore, since the pits are provided so as to be deviated to the left and right with respect to the track in advance, if the signal amount from the pit 110 and the change in the signal amount from the pit 111 are the same, the optical spot travels on the track 120. You will be moving exactly. If the signal amount from either of the pits is large or small, it is known that the optical spot is off the track 120. Therefore, the galvanomirror 8 is controlled to position the optical spot on the track 120. To

As an optical spot control, there is an automatic focus control in addition to the tracking control. This is a control that follows the fluctuation of the disk in the vertical direction and always keeps the focal point on the recording film. In the configuration example of FIG. 1, the light transmitted through the beam splitter 11 is used by an automatic focus detection optical system including a cylinder lens 20, a knife edge 21, and a split-type photodetector 22. The automatic focus control system may have a configuration used in a conventional optical disk device. That is, the focus position is the position of the aperture lens 9 at which the difference signal of the photodetector 22 becomes zero, and the voice coil 23 attached to the lens 9 is driven so that the difference signal, that is, the error signal becomes zero.

Next, a description will be given of a recording timing shift which becomes a problem when magneto-optical recording is performed by magnetic field modulation. FIG. 4 is a diagram showing a relationship between overwrite timing and a reproduction signal. Data recording area of the track on the 120, that is, light Supotsuto 140 at time t ₀ between pits 110 and 111 are located. The sum signal 18 can detect only the signals of the pit trains 110 to 112. The sum signal 18 is set to 2 at a certain threshold value.
It is input to a binarization circuit 24 for binarization, and a binarized pit signal 25 is obtained as an output. The recording clock 27 is generated by inputting the signal 25 to a PLL circuit 26 as a phase reference signal. The clock 27 is controlled by the PLL circuit 26 so as to be generated for a fixed period between pits. PLL circuit
The configuration 26 may be a configuration conventionally used for a magnetic disk, an optical disk, or the like. When the rotation accuracy of the spindle motor 2 is sufficiently high and the eccentricity of the disk 1 is small, it is possible to use a digital type PLL circuit in which the oscillation frequency is fixed and only the phase is synchronized with the pit signal 25. . Now, it is assumed that data 29 modulated by the data modulation circuit 28 is given as shown in FIG. On the other hand, the light intensity distribution 141 at time t ₀ of the light Supotsuto 140 is summer and Gaussian distributions. The formation of the magnetization domain occurs in the portion where the temperature of the perpendicular magnetization film is higher than the Curie temperature,
In order to consider the state of recording, it is necessary to consider not the light altitude distribution itself but the temperature distribution on the recording film. Temperature distribution 142 at time t ₀ is a moving amount of the optical Supotsuto 140, the balance between the thermal conductivity of the recording film, really a positionally as shown in FIG. 4, the deviation occurs. In FIG, delta ₁ Kiyuri temperature 143 to light Supotsuto center position
Deviation between the position of the above, delta ₂ is a thermal conductivity of the recording film, a deviation occurs in the linear velocity. Accordingly, the magnetization domain 144 actually recorded is formed to be shifted forward in position, and the difference signal 19 in FIG. 1, that is, the leading edge position of the reproduction signal is determined by the target modulation magnetic field. Δ than the rising position
It will be shifted by _three . If the shift amount is a fixed amount, there is no problem if the position of the modulation data 29 is shifted by that amount in advance.

However, if the recording film is not always uniform in characteristics such as thermal conductivity and Curie temperature, and recording / reproducing is performed at a constant rotation speed, the linear velocity changes depending on the recording radius position. Can not. Therefore, it is effective to simultaneously record the reference domain at the head of the data portion at the time of recording, and demodulate the data by the reproduction clock generated from the reference domain at the time of reproduction. This method requires two PLL circuits, one for recording and one for reproduction. However, even if the recording timing shift occurs as described above, accurate and accurate data demodulation can be easily achieved regardless of the recording radius position, etc. can do.

Hereinafter, the processing of this method will be described. FIG. 5 is a diagram showing a time chart of each signal when implementing the present method. The process of generating the recording clock 27 is the same as that described with reference to FIG. As the modulation data 29, a reference signal 150 is added to the head of the data. The generated magnetic domain sequence 151 is formed by adding a reference domain 152 to the head of the data section. A gate signal 31 is generated from the binarized signal 25 by a gate generation circuit 30. this is,
What is necessary is just to input the binarized signal 25 as a trigger of the mono-multi vibrator and output a signal covering the area where the reference domain 152 exists. The gate signal 31 and the signal 33 obtained by binarizing the difference signal 19 by the binarization circuit 32 are ANDed.
By calculating the logical product by the circuit 34, the binarized signal 35 of only the reference domain 152 can be extracted.
This signal 35 is input to a PLL circuit 36 and used as a phase reference signal to generate a reproduction clock 37. By demodulating the binary signal 33 by the data demodulation circuit 38 by the reproduction clock 37, accurate data recognition can be performed even when a recording timing shift occurs. If the user does not want to input the reference signal 150 to the demodulation circuit, the data demodulation circuit 38 calculates the logical product (AND) of the logical NOT (NOT) signal of the gate signal 31 and the binary signal 33.
You can just type in

The above method makes it possible to correct the recording timing shift, and it is also possible to use NRZ (non-return to zero) modulation without self-clocking as a data modulation method.

In this embodiment, the reference domain 15 immediately follows each pre-pit.
Although the case where 2 is recorded is shown, a portion occupied by the reference domain in each recording area 130 becomes overhead, and thus becomes a useless area from the viewpoint of data recording capacity. In this regard, the rotational accuracy of the spindle motor 2 is sufficiently increased, and the amount of eccentricity of the disk 1 is suppressed to a small value. If the filter band in the PLL circuit 36 for generating the reproduction clock 37 can be narrowed. The reference domain is not recorded for each pre-pit, but is recorded one by one in some recording areas, thereby generating a reproduction clock 37, whereby the overhead can be reduced.

In the embodiment shown in FIG. 1, a magneto-optical signal is obtained by a differential detection method using a half-wave plate. However, a reflected light beam is separated into two directions by a half prism, and an analyzer is provided for each. Even if a method of differential detection after insertion and light reception by the photodetector or a method of detecting the rotation of the plane of polarization by a single analyzer and obtaining a magneto-optical signal does not hinder the implementation of the present invention. Absent.

In the embodiment shown in FIG. 5, no particular operation or correction is applied to the recording position of the reference domain 152. However, if the magnetic field is applied in advance in time at the time of recording in advance by the amount of deviation of the magnetization domain from the normal position caused by the above-mentioned reason, the correction amount at the time of reproduction is reduced. Further, when the formation of the magnetization domain is delayed with time, when the reference domain 152 is formed in the clock pit 110 region, it becomes difficult to accurately read the reference domain 152. Also from this point, it is desirable to perform rough position correction in advance. This deviation amount can be grasped if the linear velocity and the characteristics of the recording material are determined.

In the embodiment shown in FIGS. 1 and 5, two PLL circuits are used for recording and reproduction. As a method for implementing the present invention using only one PLL circuit, only the phase of the clock signal 27 generated based on the clock pits 110 to 112 is varied, and the binary signal 3 obtained from the reference domain 152 is used.
There is a method of obtaining a reproduction clock 37 by synchronizing with 5. FIG. 6 is an example of an apparatus configuration for implementing the above method, and FIG. 7 is a time chart showing the operation. The delay element 62 has a function of generating several kinds of delay clock signals having different phases from the recording clock 27. In the embodiment shown in FIG. 6, delay clock signals 160 to 167 having a phase delay of .pi. / 4 radians from the input recording clock 27 are generated. In this case, the amount of delay is selected so that the phase of the delay clock signal 167 matches the phase of the input clock 27. The binarized signal 35 is a reference domain 152
Is a binarized pulse. The selector 63 selects a delay clock signal such that the phase of the rising edge of the binarized signal 35 coincides with the phase of the rising edge of the reproduction clock 37. The flip-flops 50, 51, 57 and 58 are delay type flip-flops, and are logic elements whose Q terminal output becomes "1" when a rising trigger signal is inputted to the T terminal when the D terminal is "1". Conversely, when a trigger signal is input to the T terminal when the D terminal is “0”, the Q terminal output becomes “0”. Therefore, the Q output 17 of the flip-flop 50
0 is “1” when the rising edge of the signal 35 is input in the section where the clock 27 is “1”, and becomes “0” when the rising edge of the signal 35 is input in the section where the clock 27 is “0”. Flip flop
Regarding the Q output 171 of 51, the rising edge of the signal 35 becomes “1” when the clock 27 is input in the section of “0”,
When the clock 27 is input in the section of "1", it becomes "0". Signal 172 is the NAND output of signal 170 and signal 35, and signal 173 is the NAND output of signal 171 and signal 35. These two signals 170 and 171 may be directly input to the up-count (U) and down-count (D) trigger terminals of the counter 61, respectively. However, in this case, the value of the output (A, B, C) of the counter 61 changes each time the signal 35 is input. For this reason, if there is a defect on the disk or noise of the detection system, there is a possibility of malfunction. Flip flop 57,5
Reference numeral 8 is provided to prevent this malfunction, and functions as a hysteresis register. That is, the signal 172
Alternatively, the counter 61 is not operated unless one of the rising edges of the signal 173 is continuous for two or more times. Flip-flop 57 is activated when signal 173 is "0".
The Q output 174 is reset to "0" and the flip-flop 5
When the rising edge of the signal 172 is input to the T terminal 7 and “0” is input to the R terminal, the Q output 174 becomes “1”. The signal 175 becomes “0” when the signal 172 is “0”, and becomes “1” when the signal 172 is “1” and the rising edge of the signal 173 is input. The count-up trigger signal 176 of the counter 61 is obtained by inputting the inverted signals of the signal 174 and the signal 172 to the NAND gate 59. Similarly, the countdown trigger signal 177 is obtained by the NAND gate 60. In the embodiment shown in FIG. 6, the counter 61 is a 3-bit counter,
A selection of street clock signals 160-167 is possible. With the above operation, the phase of the reproduction clock 37 can be made to coincide with the phase of the signal 35 as the Y output of the selector 63. The number of bits of the counter 61 may be increased or decreased according to the phase following characteristic, and the phase difference can be suppressed by increasing the number of bits.

In the embodiment shown in FIG. 3, tracking of the optical spot and generation of the recording clock 2 are performed by clock pits provided at equal intervals. The present invention can also be applied to the sample format proposed by ANSI (document number x 3B11 / 86-190). In the format according to the proposal, a servo byte area is provided with a tracking area, a focus control area, and a recording / reproducing clock synchronizing area as shown in FIG. In order to realize the present invention on the format, the same processing can be performed by recording the reference domain 152 immediately after the servo byte area.

〔The invention's effect〕

According to the present invention, even if a timing shift occurs between the position of the applied magnetic field generated when performing magneto-optical recording using the magnetic field modulation method and the position of the domain to be formed, the clock used for reproduction can be used as the reference domain. By demodulating the data sequence generated based on the clock and recorded by the clock, accurate data demodulation can be performed without being affected by timing deviation. Further, as a data modulation method, it can be used regardless of the presence or absence of the self-clocking property.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a magneto-optical disk apparatus of a magnetic field modulation type according to an embodiment of the present invention, FIG. 2 is a view for explaining a change in polarization direction in reproducing a magneto-optical signal, and FIG. 3 is a sample servo using prepits. FIG. 4 illustrates an example of a format, FIG. 4 illustrates a positional deviation between a recording magnetic field and a formed magnetic domain in a magnetic field modulation method, and FIG. 5 illustrates a method of correcting the influence of the positional deviation during reproduction. Time Chart, 6th
FIG. 7 is a diagram showing a configuration example for obtaining a reproduction clock by varying the phase of a recording clock, FIG. 7 is a time chart for explaining the operation of FIG. 6, and FIG. 8 is a diagram showing an example of application to a sample format. . 1 ... disk 3 ... semiconductor laser, 5 ... magnetic head, 30 ... gate generation circuit, 26, 36 ... PLL circuit, 110-1
18: Clock pit, 150: Reference signal, 152: Reference domain, 37: Clock for reproduction, 62: Delay element, 63
……selector.

Claims (12)

(57) [Claims] 1. A light beam is applied to a data recording area between marks on a magneto-optical disk on which optically detectable marks for generating a clock are arranged on a recording track. In a magneto-optical signal recording / reproducing method, a magnetic field having a polarity corresponding to a state of an input signal is applied to a region, the state of the input signal is recorded as magnetization information on a recording film, and the magnetization information is read by a magneto-optical effect. A magneto-optical signal recording / reproducing method, wherein a phase of a recording clock signal used for recording and a phase of a reproduced clock signal used for data reproduction are different. 2. The magneto-optical signal recording / reproducing method according to claim 1, wherein said recording clock signal and said reproducing clock signal are generated based on separate reference signals. 3. The recording clock signal is generated based on a read signal of a mark previously formed in a pit shape on a disk, and the reproduction clock signal is reproduced in a predetermined portion of a data recording area between the marks. 3. The magneto-optical signal recording / reproducing method according to claim 2, wherein reference magnetization information to be a reference at the time of clock generation is recorded, and the reference magnetization information is generated based on a read signal of the reference magnetization information. 4. The magneto-optical signal recording / reproducing method according to claim 1, wherein said reproducing clock signal is generated by changing a phase of said recording clock signal. 5. The recording clock signal is generated on the basis of a read signal of a mark previously formed in a pit shape on a disk, and the reproduction clock signal is provided in a predetermined portion of a data recording area between the marks. 5. The reproduction clock according to claim 4, wherein reference magnetization information to be a reference at the time of generation is recorded, and the reproduction clock is generated by changing a phase of the recording clock signal based on a read signal of the reference magnetization information. The magneto-optical signal recording / reproducing method according to the above. 6. A magneto-optical signal recording / reproducing method according to claim 3, wherein said reference magnetization signal is recorded at a head portion of said data recording area. 7. A position of magnetization information formed on a recording film,
7. The method according to claim 1, wherein the amount of deviation from the position of the magnetic field applied during recording is compensated to shift the position of application of the recording magnetic field in advance. The magneto-optical signal recording / reproducing method according to the above. 8. An optical disk on which information is recorded optically,
An optical head for irradiating the optical disk with a light beam; a magnetic field applying means for applying a magnetic field modulated in accordance with information to be recorded at a predetermined position on the optical disk to which the optical beam is irradiated; and detecting light returning from the optical disk A light detector;
A reproducing circuit for reproducing a signal recorded on the basis of a signal from the photodetector; and a recording clock signal system for controlling the drive timing of the magnetic field applying means in an optical disk device for optically recording and reproducing information. And an optical disc apparatus having two clock signal systems of a reproduction clock signal system for controlling the drive timing of the reproduction circuit. 9. The optical disk has a servo area having pits formed in advance along a track and a data area where data is to be recorded alternately, and the photodetector has different polarization components of light returning from the optical disk. And the reproducing circuit has an adding circuit for adding signals from the two detectors and a subtracting circuit for subtracting signals from the two detectors, and the recording clock 9. The optical disk device according to claim 8, wherein the signal system forms a clock signal based on a signal corresponding to the pit output from the adding circuit. 10. The optical disk device according to claim 9, wherein said reproduction clock signal system forms a clock signal based on a signal output from said subtraction circuit. 11. The reproduction clock signal system outputs a signal obtained by changing the phase of a clock signal formed by the recording clock signal system, based on a signal output from the subtraction circuit. 10. The optical disk device according to claim 9. 12. A reproduction clock signal system comprising: a plurality of delay circuits for delaying a clock signal formed by the recording clock signal system with different delay times; and a plurality of clocks having different phases formed by the delay circuits. 12. The optical disk device according to claim 11, further comprising: a selector that outputs a clock having a pulse whose phase matches that of a binarized signal of the signal output from the subtraction circuit.