JPH1125535A - Method for adjusting phase between laser and magnetic field when magneto-optical disk is recorded and magneto-optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the high density recording of high quality by recording an isolated mark with magnetic field modulation synchronized with a clock, pulse irradiating this recording mark and adjusting timing of magnetic field switching and laser irradiation to a phase optimum state from a reproduced output level. SOLUTION: A test-write pattern signal synchronized with the clock is supplied to a magnetic field applying magnetic head 3, and a test-write mark recorded on a disk 1 is irradiated by reproducing laser pulse light, and a signal is reproduced through an optical pickup 4, a matrix amplifier 51 and a magneto- optical difference signal circuit 53. A laser pulse generated synchronized with the clock is changed in phase through a phase adjustment circuit 45 to be adjusted so that a reproduced level of an obtained regenerative signal becomes maximum. Since irradiation timing of a laser and switching timing of a magnetic field on the real disk are optimized, stable high density recording is obtained without dispersion in a recording medium, a temp. change, etc., also.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting the phase of a laser and a magnetic field during recording on a magneto-optical disk, and a magneto-optical disk apparatus using the same, and more particularly to a magnetic field required for high-density recording. And a phase adjustment method of laser irradiation.

[0002]

2. Description of the Related Art Conventional magneto-optical disk recording methods include optical modulation recording in which a constant magnetic field is applied to modulate the intensity of laser power in accordance with data, and the polarity of the magnetic field in accordance with data in which the intensity of laser light is kept constant. There are two types of methods, that is, a magnetic field modulation recording method for reversing the above. Further, in the magnetic field modulation recording method, a continuous laser irradiation magnetic field modulation recording method in which a constant laser power is continuously applied during recording to raise the temperature of the recording medium and only the magnetic field is reversed, and the laser power is continuously applied at a constant power. Patent No. 257
No. 6643, the laser is intermittently
That is, there is a laser pulse irradiation magnetic field modulation recording method in which pulse-like continuous irradiation is performed.

[0003]

Among the above-mentioned prior arts, in the laser pulse irradiation magnetic field modulation recording system, the relationship between laser irradiation timing and magnetic field switching timing is important. That is, by irradiating a laser in a pulsed manner, the temperature of the recording film is measured to increase.
The temperature of the recording film rises above a predetermined temperature, and then the laser irradiation stops, so that the temperature of the recording film falls below the predetermined temperature. This temperature transition process and the timing of the application of a magnetic field form magnetization marks. Is done.

Therefore, when a magnetization mark is formed, a magnetic field must be applied at a predetermined timing. However, since the modulation speed of the magnetic field is finite, if a recording mark is formed in a transient state of the magnetic field, a normal mark is not formed, which causes deterioration of signal quality. Especially,
In a region where the recording density is increased and the transition time of the rise and fall of the magnetic field cannot be ignored, it is necessary to accurately adjust the laser pulse irradiation timing and the magnetic field switching timing. However, this point is not considered at all in the conventional laser pulse irradiation magnetic field modulation recording method.

[0005] The present invention has been made in view of the above points,
The purpose is to record by adjusting the laser irradiation timing and the magnetic field switching timing to the phase optimized state in the laser pulse irradiation magnetic field modulation recording method that simultaneously modulates and records both the laser and the magnetic field. This makes it possible to achieve high-quality, high-density recording.

[0006]

In order to achieve the above-mentioned object, in one solution according to the present invention, an isolated mark corresponding to the switching of a magnetic field is modulated in advance by magnetic field modulation based on a certain reference timing. Recording is performed, and the recording mark is reproduced while irradiating pulses.
In this manner, a maximum signal can be obtained when there is the timing of the isolated mark, that is, the timing of the magnetic field and the timing of the reproduction pulse, that is, the timing of laser irradiation. At this time, the optimum phase at the time of recording is determined from the phase relationship between the two, and a correction circuit that corrects the current phase difference so as to match this phase is used. A method of always recording by correction is used.

In another solution according to the present invention, a disk having a structure having an in-plane magnetized film is used as a magneto-optical disk, and a magnetic field is irradiated in the reproduction mode in a solitary wave form, so that the reproduction system uses the magnetic field. Detect changes. Similarly, by irradiating a reproduction laser power that is not recorded in the reproduction mode with a solitary wave, a signal due to a change in light amount is detected. By combining these two detection methods, it is possible to detect the phase of the solitary wave of the laser power and the solitary wave of the magnetic field, and thus the optimum phase correction amount is obtained.

In still another solution according to the present invention, a signal is actually recorded by changing the pulse irradiation timing and the switching timing of the magnetic field, and the signal quality is evaluated. Find the phase.

By using these techniques, an optimum phase correction amount is detected, and this value is fed back to a laser driving circuit or a magnetic head driving circuit, whereby the phase can be optimized.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. First, a first embodiment of the present invention will be described. FIG. 1 is a configuration diagram of a magneto-optical disk device according to a first embodiment of the present invention. The magneto-optical disk device of each embodiment according to the present invention, including the magneto-optical disk device of the present embodiment, emits laser pulses. This is a magneto-optical disk device capable of recording by a magnetic field modulation recording method.

In FIG. 1, reference numeral 1 denotes a magneto-optical disk (hereinafter referred to as a disk), 2 denotes a spindle motor, 3 denotes a magnetic head for applying a magnetic field, 4 denotes an optical pickup (hereinafter referred to as a pickup), and 31 denotes a magnetic head. Drive circuit, 32
Is a pattern generation circuit, 41 is an optical system, 42 is a photodetector, 43 is a laser driving circuit, 44 is a laser pulse generation circuit, 45 is a phase adjustment circuit, 51 is a matrix amplifier, 52 is an intensity signal (sum signal), and 53 is A magneto-optical signal (difference signal), 55 is a level detection circuit, and 56 is a clock generation circuit.

In the configuration described above, on the disk 1,
The laser light is condensed and heated by the pickup 4, the magnetic field is switched by the magnetic head 3 according to the information, and the magnetization information is recorded on the disk 1. The disk 1 is rotated at a predetermined rotation speed by a spindle motor 2. In the present embodiment, the CLV method in which the linear velocity of the disk 1 is constant is used. For this reason, the rotation speed of the spindle motor 2 changes with the radial position. For the disk (magneto-optical disk) 1, magnetic super-resolution using a temperature distribution by a reproducing beam was used.

The magnetic head 3 includes a magnetic head drive circuit 3
A drive current is supplied from 1 according to the information. The signal pattern sent to the magnetic head drive circuit 31 is generated by a pattern generation circuit 32. The recording pattern differs depending on the signal. When recording normal data, a pattern corresponding to the recording data is created. In this embodiment, phase control by trial writing is performed to optimally record data. In this case, a special pattern is generated and a test signal is recorded.

The pickup 4 includes an optical system 41 including an objective lens for condensing a laser, a photodetector 42 for detecting reproduction light, and the like. The laser source in the pickup 4 is generated by a laser pulse generation circuit 44. It is connected through a laser drive circuit 43 for emitting a pulse of laser light. As described above, the recording method applied by the present invention is a laser pulse irradiation magnetic field modulation recording method that irradiates a laser in a pulse shape and switches and records a magnetic field according to information. The laser is continuously irradiated in a pulse shape, and a pulse synchronized with a clock is usually irradiated. In the present embodiment, a pulse synchronized with the clock is used.
Generates a laser pulse based on the clock generated by the clock generation circuit 56.

Between the laser pulse generation circuit 44 and the laser drive circuit 43, there is provided a phase adjustment circuit 45 for adjusting the phase with respect to the clock in order to adjust the phase with the magnetic field. The phase adjustment circuit 45 is constituted by a delay circuit, and delays the timing of pulse generation by a predetermined time. The amount of delay can be varied according to the result of the phase adjustment described later, and it is possible to set an optimum recording state by the delay adjustment, that is, the phase adjustment.

The output of the photodetector 42 of the pickup 4 (the detection signals of the P and S polarization components) passes through a matrix amplifier 51 and is output as a sum signal 52 as a signal intensity and a difference signal 53 as a magneto-optical signal. Using the difference signal (magneto-optical signal) 53, the level detection circuit 55 compares and evaluates the relationship between the phase and the signal to determine the optimum phase. When actually performing test recording and evaluating the relationship between the phase and the signal, the signal at each phase is evaluated by slightly shifting the phase by the phase adjustment circuit 45.

A method for detecting phase information according to the present embodiment will be described with reference to FIG. First, an isolated mark is recorded by magnetic field modulation recording. Next, the isolated mark is reproduced by irradiating an isolated laser pulse. As shown in FIG. 2, the laser driving circuit 43
The actual laser irradiation position is delayed with respect to the signal input to. The laser drive signal is synchronized with the clock.

As described above, since the recording mark is recorded by the magnetic field modulation recording, the switching timing of the magnetic field coincides with the formation position of the recording mark. When reproduction is performed in such a state, the reproduction signal level becomes the maximum value when the relationship between the laser emission position and the recording mark is optimal.
Therefore, this position is a condition where the switching timing of the magnetic field and the laser emission timing coincide. In particular, in this embodiment, a magnetic super-resolution disk is used as the disk 1, and the output of the magnetic super-resolution disk with respect to the laser power is larger than that of a normal disk, so that the phase shift can be recognized more remarkably.

FIG. 3 shows signals when test recording is actually performed. In a method of actually examining the phase relationship, the phase of the laser is gradually shifted with respect to the clock. FIG.
As shown in FIG.
The phase corresponding to 4 is shifted. Then, when the light emission of the laser deviates from the recording mark point, only the same minute signal as in normal DC reproduction can be obtained. However, as the phase shifts, the signal level increases as the irradiation on the recording mark approaches. In this embodiment, since the disk is a magnetic super-resolution disk, the difference is particularly remarkable. That is, since the aperture is hardly opened at the low-power DC reproduction level, the signal level is small. On the other hand, the temperature is increased until the aperture is opened by the pulse, so that the signal level sharply increases. In a normal disk, a condition that the power is doubled, for example, 1 m
At 2 mW relative to W, only twice the signal strength is obtained. On the other hand, in a magnetic super-resolution disk, a difference in signal intensity of 10 times or more is obtained with respect to double power. Therefore, when a magnetic super-resolution disk is used as in the present embodiment, the discrimination is easier.

FIG. 4 shows the result of evaluating the relationship between the phase and the signal level. As a result, a signal level of about 30 dB (30 times) was measured between the phase optimum value and the non-optimal value.

In this embodiment, an example using an isolated mark is shown, but a repetitive signal may be used. When a repetition signal is used, the detection becomes easy because the reproduction signal is a continuous signal.

As described above, according to the present embodiment, when reproducing a previously recorded mark, the mark is reproduced by pulse irradiation, and the pulse timing and the signal level are compared and checked. You can know the phase relationship. Further, by using the position where the signal level has the maximum value as the optimum phase, it is possible to avoid signal deterioration due to a phase shift between the laser and the magnetic field.

Next, a second embodiment of the present invention will be described. FIG. 5 is a configuration diagram of a magneto-optical disk drive according to a second embodiment of the present invention. In FIG. 5, components equivalent to those of the previous embodiment are denoted by the same reference numerals. The same applies to the third embodiment.) In FIG. 5, 33 is a phase adjustment circuit, and 54 is a phase comparison circuit.

In the configuration shown in FIG. 5, the disk 1 is driven to rotate by a spindle motor 2 in a CLV manner, and a laser beam is focused on the disk 1 by a pickup 4 and heated. By switching according to the information, the magnetization information is recorded on the disk 1.

The magnetic head 3 includes a magnetic head drive circuit 3
A drive current is supplied from 1 according to the information. The signal pattern sent to the magnetic head drive circuit 31 is generated by a pattern generation circuit 32. The recording pattern differs depending on the signal. When recording normal data, a pattern corresponding to the recording data is created. In order to optimally record data, phase control by trial writing is also performed in the present embodiment. In this case, a special pattern is generated and a test signal is recorded.

Between the pattern generating circuit 32 and the magnetic head driving circuit 31, there is provided a phase adjusting circuit 33 for adjusting the phase with the laser pulse. This phase adjustment circuit 33
Is equivalent to a distortion-free delay circuit, and the pattern generation circuit 3
2 has a function of delaying the pulse signal generated in 2 for a predetermined time.

The pickup 4 includes an optical system 41 including an objective lens, a photodetector 42, and the like. The laser generation source in the pickup 4 is a laser pulse generation circuit 4
The pulse generated in step 4 is connected through a laser drive circuit 43 for emitting laser light. A signal from the detector 42 of the pickup 4 is converted by a matrix amplifier 51 into a sum signal 52 and a difference signal 53 corresponding to a magneto-optical signal.
Are output as two types of signals. These two signals are compared by the phase comparison circuit 54, and the phases of the sum signal and the difference signal are detected.

Next, the disk (magneto-optical disk) 1 used in this embodiment will be described. FIG. 6 shows a cross-sectional view of a disk to be used, and FIG. 7 shows Kerr rotation angle characteristics (Kerr loop) with respect to an external magnetic field of the disk.

As shown in FIG. 6, the disk 1 is
1, an interference film 12 and a reproducing layer 13 using an in-plane magnetization film
A recording layer 14 using a perpendicular magnetization film for recording information,
It has a structure in which protective layers (not shown) are sequentially formed. The laser enters from the substrate 11 side through the objective lens of the optical system 41, passes through the interference layer 12, and is mainly reflected by the reproduction layer 13.

The Kerr curve shown in FIG. 7 is a result measured at room temperature. FIG. 7A shows the recording layer 14, and FIG. 7B shows the reproducing layer 13. In this embodiment, an alloy of gadolinium (Gd), iron (Fe), and cobalt (Co) is used for the reproducing layer 13, and an alloy of terbium (Tb), iron (Fe), and cobalt (Co) is used for the recording layer 14. Is used. The reproducing layer 13 shows the in-plane magnetic characteristics shown in FIG. 7B at room temperature, but shows the perpendicular magnetic characteristics shown in FIG. 7A above a certain temperature. In this embodiment,
It exhibits perpendicular magnetic characteristics at about 140 ° C. or higher.

The reproducing power during continuous irradiation during reproduction is 2 mW
Under this condition, the reproducing layer 13 irradiated with the laser is
Of the recording layer 14 is transferred to the reproducing layer 13. In the reproduction using the magnetic super-resolution, a part of the reproduction layer 13 in the laser beam thus irradiated has perpendicular magnetic characteristics, and information recorded on the recording layer 14 is transferred to the reproduction layer 13 for reproduction. Is what you do.

However, when the temperature of the reproducing layer is 140 ° C. or lower, the material exhibits in-plane magnetic characteristics, and an external magnetic field is applied to the material having the in-plane magnetic characteristics shown in FIG. When applied, the Kerr rotation angle changes according to the external magnetic field strength, and the output of the magneto-optical signal 53 changes corresponding to this change.

Hereinafter, this principle will be described with reference to FIGS. FIG. 8 shows an interference film 12 on a substrate 11 for explanation.
9 shows a state where only the in-plane magnetization film (reproducing layer) 13 is formed, and FIG. 9 shows a Kerr loop at this time.

A waveform 101 shown on the lower side of FIG. 9 is an applied magnetic field, and corresponds to an external magnetic field. A waveform 102 shown on the horizontal side of FIG. 9 is a change in the Kerr rotation angle, and corresponds to an output detected by the reproduction system. As can be seen from this figure, when an external magnetic field is applied by the magnetic head 3, this waveform 10
A signal output corresponding to 2 is obtained. This is a low-temperature signal indicating in-plane magnetic characteristics. Therefore, by applying a magnetic field in a reproducing state, a signal corresponding to the applied magnetic field can be obtained.

In the present embodiment, when the reproduction laser is irradiated in a pulse shape, the output of the sum signal 52 changes according to the irradiation pulse. On the other hand, when a magnetic field is applied in a pulsed manner, FIG.
The magneto-optical signal (difference signal 53) also changes greatly due to the effect shown in FIG. From this, the sum signal 52 due to laser irradiation
And the magneto-optical signal (difference signal 53) obtained by modulating the external magnetic field, the phase relationship between the laser and the magnetic field can be known.

Next, the relationship between signals will be described with reference to FIG. It is assumed that the timings of the magnetic head drive circuit 31 and the laser drive circuit 43 are synchronized.

As shown in FIG. 10, first, a magnetic field of a solitary wave is applied by the magnetic head driving circuit 31 at time t ₀ .
An isolated signal is output as a magneto-optical signal 53 corresponding to the isolated wave. The time at this time is defined as t _M. On the other hand, similarly, when the laser is radiated in an isolated manner at the time t ₀ , an isolated signal is generated as an intensity signal (sum signal) 52 corresponding to the isolated wave.
Is output as The time t _L at this time is the timing of laser irradiation. Therefore, the timing of the laser and the magnetic field is Δt = (t _M −t _L ).

Next, waveforms in an actual phase adjustment method will be described. FIG. 11 shows a current waveform (magnetic field waveform) applied to the magnetic head and a waveform of the laser drive current. In the present embodiment, the phase of the magnetic field is changed from Δ1 to Δ4.

FIG. 12 shows a reproduced signal waveform at this time. The difference signal 53 is a signal corresponding to a magneto-optical signal.
As described with reference to FIG. 9, in the case of a material using an in-plane magnetized film, a signal can be obtained corresponding to an external magnetic field. In addition, since the intensity changes also with respect to laser irradiation, a signal is output according to the intensity. On the other hand, the sum signal 52 has nothing to do with the magnetization and responds only to the intensity of light, so that an output is obtained corresponding to only the laser intensity. Therefore, an optimal phase can be obtained by comparing the phases of these isolated waveforms.

According to the present embodiment, since the phase can be optimized in the reproducing state, the time required for the phase adjustment can be shortened. Therefore, there is an effect that the time until the actual use of the disk is shortened and the waiting time is reduced. Further, since the phase can be optimized in the reproducing state, there is an advantage that the adjustment can be temporarily performed by interruption even during the reproduction of other data.

Next, a third embodiment of the present invention will be described. The present embodiment is an embodiment in which a signal is actually recorded while changing the phase, and an optimum phase is obtained from the evaluation of the error rate of the recording result. FIG. 13 is a configuration diagram of a magneto-optical disk device according to the third embodiment of the present invention. In FIG. 13, reference numeral 60 denotes an error rate measurement circuit.

In the configuration shown in FIG. 13, the disk 1 is driven to rotate by the spindle motor 2 by the CLV method, the laser light is focused on the disk 1 by the pickup 4 and heated, and the external magnetic field is applied by the magnetic head 3. By switching according to the information, the magnetization information is recorded on the disk 1.

The magnetic head 3 includes a magnetic head drive circuit 3
A drive current is supplied from 1 according to the information. The signal pattern sent to the magnetic head drive circuit 31 is generated by a pattern generation circuit 32. The recording pattern differs depending on the signal. When recording normal data, a pattern corresponding to the recording data is created. In order to optimally record data, phase control by trial writing is also performed in the present embodiment. In this case, a special pattern is generated and a test signal is recorded.

Between the laser pulse generating circuit 44 and the laser driving circuit 43, there is provided a phase adjusting circuit 45 for adjusting the phase with respect to the clock in order to adjust the phase with the magnetic field. The phase adjustment circuit 45 is constituted by a delay circuit, and delays the timing of pulse generation by a predetermined time. The amount of delay can be varied according to the result of the phase adjustment described later, and it is possible to set an optimum recording state by the delay adjustment, that is, the phase adjustment.

The pickup 4 includes an optical system 41 including an objective lens, a photo detector 42, and the like. The laser generation source in the pickup 4 is a laser pulse generation circuit 4
The pulse generated in step 4 is connected through a laser drive circuit 43 for emitting laser light. A signal from the detector 42 of the pickup 4 is converted by a matrix amplifier 51 into a sum signal 52 and a difference signal 53 corresponding to a magneto-optical signal.
Are output as two types of signals.

The output magneto-optical signal (difference signal 5)
3) is compared with the input pattern, and the error rate measurement circuit 6
The error rate is obtained from 0. When test recording is actually performed to evaluate the relationship between the phase and the signal, the phase is slightly shifted by the phase adjustment circuit 45, and the error rate at each phase is measured to determine the optimum phase.

In this embodiment, as described above, the error rate is used for signal evaluation. This is because, as shown in FIG. 14, the influence of the phase shift on the signal does not affect the signal level but the noise level, so that the level detection cannot evaluate the effect of the phase. FIG.
As can be seen from FIG. 4, the carrier level C hardly changes with respect to the phase change, and only the noise N greatly changes. Due to this effect, the error rate greatly changes as shown in FIG. In the present embodiment, the optimum phase is obtained by detecting the change in the error rate.

As described above, according to the present embodiment, since the phase is optimized based on the actual error rate, there is an effect that the reliability is high and the phase can be adjusted in an optimum state.

FIGS. 16 and 17 show a test area on the disk 1 for performing the phase adjustment described in each of the above embodiments.

In the example shown in FIG. 16, test areas 71 and 72 are provided on the inner and outer circumferences of the recording area 70. In each embodiment of the present invention, the phase adjustment is performed in the test area 71 or the test area 72 before starting the recording / reproduction immediately after the disk exchange. In a system in which the linear velocities are different between the inner and outer circumferences, that is, in CAV and ZCAV, the phase is adjusted in the test areas 71 and 72 on the inner and outer rims, and the correction based on the difference in the linear velocities is performed.

In the example shown in FIG. 17, test areas 71 and 72 are provided on the inner and outer circumferences of the recording area 70, and a test area 73 is provided at the first position of the sector. In each of the embodiments of the present invention, test writing is performed in the test areas 71 and 72 on the inner and outer circumferences to determine the optimum phase. However, the test area 73 in the sector area is read as a test in the reproduction state as described in the second embodiment. However, it is used to check whether a phase shift has occurred.

[0052]

As described above, according to the present invention, in a laser pulse irradiation magnetic field modulation recording system in which both a laser and a magnetic field are simultaneously modulated and recorded, the actual laser irradiation timing on the disk and the magnetic field By detecting the switching timing, it is possible to perform recording with an optimal phase relationship. Therefore, in high-density recording, sensitivity fluctuations caused by variations in the laser or medium, changes in recording conditions due to ambient temperature changes, etc. And high-density recording can always be performed stably.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a magneto-optical disk device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between a recording mark by trial writing and a reproduction signal according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a relationship between a laser waveform and a reproduction output at the time of phase adjustment in the first embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a relationship between a phase and a signal level.

FIG. 5 is a block diagram illustrating a configuration of a magneto-optical disk device according to a second embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a structure of a magneto-optical disk used in a second embodiment of the present invention.

7 is an explanatory diagram showing Kerr rotation angle characteristics of the magneto-optical disk of FIG.

FIG. 8 is a simplified explanatory diagram showing a structure of a magneto-optical disk used in a second embodiment of the present invention.

9 is an explanatory diagram showing Kerr rotation angle characteristics and the like of an in-plane magnetized film of the magneto-optical disk of FIG. 7;

FIG. 10 is an explanatory diagram showing a relationship between signal waveforms according to the second embodiment of the present invention.

FIG. 11 is an explanatory diagram showing a relationship between a magnetic field and a laser waveform at the time of phase adjustment in a second embodiment of the present invention.

FIG. 12 is an explanatory diagram showing a reproduced waveform at the time of phase adjustment according to the second embodiment of the present invention.

FIG. 13 is a block diagram illustrating a configuration of a magneto-optical disk device according to a third embodiment of the present invention.

FIG. 14 shows phase, C (carrier level), and N (noise).
FIG. 4 is an explanatory diagram showing a relationship with the above.

FIG. 15 is an explanatory diagram showing a relationship between a phase and an error rate.

FIG. 16 is an explanatory diagram showing an example of a test area on a magneto-optical disk used in an embodiment of the present invention.

FIG. 17 is an explanatory diagram showing another example of the test area on the magneto-optical disk used in the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magneto-optical disk (disk) 2 Spindle motor 3 Magnetic head for applying a magnetic field 4 Optical pickup (pickup) 11 Substrate 12 Interference film 13 Reproduction layer using in-plane magnetization film 14 Recording layer using perpendicular magnetization film 31 Magnetic head Drive circuit 32 Pattern generation circuit 33 Phase adjustment circuit 41 Optical system 42 Photodetector 43 Laser drive circuit 44 Laser pulse generation circuit 45 Phase adjustment circuit 51 Matrix amplifier 52 Intensity signal (sum signal) 53 Magneto-optical signal (difference signal) 54 Phase comparison Circuit 55 Level detection circuit 56 Clock generation circuit 60 Error rate measurement circuit 70 Data area 71, 72, 73 Test area

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuhito Tanaka 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Multimedia Systems Development Division of Hitachi, Ltd. (72) Inventor Takeshi Maeda Yoshida, Totsuka-ku, Yokohama, Kanagawa No. 292, Hitachi, Ltd. Multimedia System Development Division, Hitachi, Ltd. (72) Inventor Shimitsu Higuchi 292, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture, Ltd. Multimedia System Development Division, Hitachi, Ltd. (72) Inventor Hitoshi Watanabe Osaka 1-88 Ushitora, Ibaraki-shi, Hitachi Hitachi Maxell Co., Ltd.

Claims (9)

[Claims] 1. An optical system for narrowing a laser to a small area using a lens, a tracking servo function for controlling a laser at a predetermined position, and a function for detecting a signal from a magneto-optical disk. In the laser pulse irradiation magnetic field modulation recording method of recording by switching the direction of magnetization by constantly irradiating a laser on the magneto-optical disk in a pulsed form and switching an external magnetic field according to information, A laser for recording on a magneto-optical disk, wherein a mark recorded by a modulation recording method is reproduced by irradiating a reproduction laser in a pulsed manner and an optimum phase is determined by a reproduction level of the reproduction signal. And phase adjustment method of magnetic field. 2. The magnetic super-resolution disk according to claim 1, wherein the magneto-optical disk used is a magnetic super-resolution disk for reproducing by narrowing an aperture of a reproducing beam from an apparent diffraction limit of light by utilizing a temperature distribution during reproduction. A phase adjusting method of a laser and a magnetic field at the time of recording on a magneto-optical disk. 3. A means for irradiating reproduction power in a pulse form, a signal level detecting section when the reproduction power is radiated, and a phase adjusting section capable of adjusting at least one of timing of magnetic field application or laser irradiation. A magneto-optical disk recording device having a function of performing optimal phase adjustment by test recording. 4. An optical system for narrowing a laser to a minute area using a lens, a tracking servo function for controlling the laser at a predetermined position, and a function for detecting a signal from a magneto-optical disk. A laser pulse irradiation magnetic field modulation recording method for irradiating a laser on the magneto-optical disk constantly in a pulsed manner and switching an external magnetic field in accordance with information to thereby switch and record the direction of magnetization; Using an in-plane magnetized film for at least a part of the magnetic disk, reproducing by irradiating a reproducing laser in a pulse form, and applying an external magnetic field in a pulse form, the intensity signal and the magneto-optical signal at this time are compared. A phase adjusting method of a laser and a magnetic field at the time of recording on a magneto-optical disk, wherein an optimum phase is determined from a phase difference. 5. The magneto-optical disk according to claim 4, wherein the magneto-optical disk having the in-plane magnetized film performs reproduction by narrowing an aperture of a reproduction beam from an apparent diffraction limit of light using a temperature distribution during reproduction. A phase adjusting method of a laser and a magnetic field at the time of recording on a magneto-optical disk, which is a super-resolution disk. 6. A laser pulse irradiation magnetic field modulation recording system in which a laser is constantly irradiated on a magneto-optical disk in a pulsed manner, and an external magnetic field is switched in accordance with information, thereby switching and recording a magnetization direction. In the magneto-optical disk device to be used, at least means for irradiating a reproduction laser in a pulse shape at the time of reproduction, and means for applying an external magnetic field in a pulse shape,
A means for simultaneously modulating the laser and the magnetic field; and a means for adjusting the timing of signal generation of at least one of the laser and the magnetic field. A magneto-optical disk device comprising means for detecting a phase difference between signals. 7. An optical system for narrowing a laser to a minute area using a lens, a tracking servo function for controlling a laser at a predetermined position, and a function for detecting a signal from a magneto-optical disk. In the laser pulse irradiation magnetic field modulation recording method of recording by switching the direction of magnetization by constantly irradiating the laser on the magneto-optical disk in a pulse shape and switching an external magnetic field according to information, A phase adjusting method of a laser and a magnetic field at the time of recording on a magneto-optical disk, wherein test writing is performed at a different phase in a test writing region of a magnetic field, and the phase of the laser and the magnetic field is adjusted according to signal quality. 8. The method according to claim 7, wherein the signal quality is evaluated by an error rate. 9. A magneto-optical device having means for changing the phase of at least one of a laser and a magnetic field, and means for measuring an error rate, and having a function of changing the phase in response to a change in the error rate. Disk device.