JP2002109796A - Method for detecting magnetic field strength and magnet-optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for detecting a magnetic field strength which detects the strength of the magnetic field which concentrates on the core of a magnetic head from a magnet which executes the focusing servo or the tracking servo of an objective lens. SOLUTION: A direct magnetic field DC1 or DC2 is generated by passing an electric current through the coil 302 of the magnetic head 30 in a fixed direction. When a magnetic domain having a magnetization 102 transferred to a reproducing layer 101 from the recording layer of a magnet-optical recording medium is reproduced, the magnetic head 30 impresses the direct magnetic field DC1 whose direction is opposite to that of the magnetization 102 with strength changed, and when the magnetic domain having a magnetization 103 is reproduced, the magnetic head 30 impresses the direct magnetic field DC2 whose direction is opposite to that of the magnetization 103 with strength changed. An average value of the two direct magnetic fields where the number of errors of reproduction signals detected with a laser beam LB begins to radically increase is determined to be the strength of an influential magnetic field from the magnet used for the servo of the objective lens.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic field intensity detecting method for detecting the intensity of an influencing magnetic field from a servo magnet of an objective lens for converging and irradiating a laser beam onto a magneto-optical recording medium, and removing the influencing magnetic field. The present invention relates to a magneto-optical disk device capable of reproducing signals from a magneto-optical recording medium.

[0002]

2. Description of the Related Art Magneto-optical recording media have attracted attention as rewritable, large-capacity, and highly reliable recording media, and have begun to be put to practical use as computer memories and the like. Recently, the recording capacity has been increased to 6.0 Gbyte.
es magneto-optical recording medium is AS-MO (Advanced)
Storage Magneto Opticald
isk) It is standardized as a standard and is about to be put to practical use.

When recording a signal on such a magneto-optical recording medium, a magnetic head is brought into contact with the surface of the magneto-optical recording medium on which the magnetic layer is formed, and the magneto-optical recording medium is rotated at a predetermined rotation speed. A magnetic field modulated by a recording signal is applied to the magnetic layer of the magneto-optical recording medium while the magnetic head is floated. Then, a laser beam is irradiated from the side opposite to the magnetic head to heat a predetermined region of the magnetic layer of the magneto-optical recording medium to a certain temperature or higher. Thereby, a magnetic domain having a different magnetization direction is formed in the recording layer of the magnetic layer based on the recording signal, and the signal is recorded.

When a signal is reproduced from a magneto-optical recording medium, a laser beam is applied to transfer a magnetic domain in a region heated to a predetermined temperature or higher to a reproducing layer. It is detected as the rotation angle of the polarization plane of light. Thus, a signal is reproduced from the magneto-optical recording medium. in this case,
A magnetic head is arranged on the side opposite to the side on which the laser beam is irradiated, but the magnetic head is not in contact with the magneto-optical recording medium and is away from the magneto-optical recording medium during signal reproduction. .

[0005]

However, when a signal is recorded on a magneto-optical recording medium and then the recorded signal is reproduced, the magnetic head is connected to the magneto-optical recording medium from the viewpoint of prompt signal reproduction. A signal is reproduced by irradiating a laser beam from the side opposite to the magnetic head in a state of contact.

If a signal is to be reproduced from the magneto-optical recording medium while the magnetic head is in contact with the magneto-optical recording medium,
It is said that the magnetic force from the magnet that performs the focus servo or tracking servo of the objective lens that focuses and irradiates the laser beam on the magneto-optical recording medium concentrates on the core (magnetic material such as ferrite) of the magnetic head and adversely affects the reproduction signal. There's a problem.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to detect a magnetic field intensity concentrated on a core of a magnetic head from a magnet that performs focus servo or tracking servo of an objective lens. The present invention provides a method for detecting a magnetic field intensity.

It is another object of the present invention to eliminate the effect of a magnetic field concentrated on a core of a magnetic head from a magnet for performing focus servo or tracking servo of an objective lens based on a detected magnetic field strength. It is an object of the present invention to provide a magneto-optical disk device capable of reproducing a signal from a disk.

[0009]

SUMMARY OF THE INVENTION A detecting method according to the present invention detects a magnetic field intensity exerted on a laser beam irradiation point by a servo magnet of an objective lens for irradiating a laser beam to a magneto-optical recording medium. A method for detecting a magnetic field intensity, comprising irradiating a magneto-optical recording medium with a laser beam, and applying a DC magnetic field in a first direction while changing the intensity at an irradiation point to reproduce a signal from the magneto-optical recording medium. Step 1, a second step of detecting the number of errors in the reproduced signal reproduced in the first step, and applying a direct current magnetic field in a second direction opposite to the first direction to the irradiation point to generate light. A third step of reproducing the signal from the magnetic recording medium, a fourth step of detecting the number of errors in the reproduced signal reproduced in the third step, and a detection in the second and fourth steps. Based on the relationship between the number of errors and the DC magnetic field intensities, and a fifth step of detecting the impact strength of the magnetic field magnet on the irradiation point.

In the method for detecting the magnetic field intensity according to the present invention, a laser beam is applied to a magneto-optical recording medium, and a DC magnetic field is applied to an irradiation point of the laser beam while changing the intensity. Then, the number of errors in the reproduced signal is detected. The detection of the number of errors is performed when a DC magnetic field in two directions is applied, and the strength of the influencing magnetic field is determined from the relationship between the number of errors in the reproduction signal and the strength of the DC magnetic field.

Therefore, according to the present invention, the intensity of the influence magnetic field from the servo magnet of the objective lens can be easily detected by applying a DC magnetic field to the magneto-optical recording medium and detecting the number of errors in the reproduction signal. can do.

Preferably, in the relationship between the number of detected errors and the strength of the DC magnetic field, when the strength of the DC magnetic field is increased in the first direction, the first magnetic field strength at which the number of errors starts to increase; When the intensity of the DC magnetic field is increased in the direction of 2, a second magnetic field intensity at which the number of errors starts to increase is detected, and an average value of the first magnetic field intensity and the second magnetic field intensity is determined as an influence magnetic field intensity. decide.

In the relationship between the number of errors in the reproduced signal and the strength of the DC magnetic field, there are two DC magnetic field strengths at which the number of errors starts to increase sharply. Then, the intensity of the influence magnetic field is determined by detecting the two DC magnetic field intensities and calculating the average value.

Therefore, according to the present invention, the intensity of the affected magnetic field can be easily and accurately obtained.

[0015] Preferably, in the first and third steps, a random data pattern recorded on the magneto-optical recording medium is reproduced.

A random data pattern recorded on a magneto-optical recording medium is reproduced, and the intensity of the affected magnetic field is determined based on the number of errors in the reproduced signal.

Therefore, according to the present invention, the data of a specific pattern for detecting the intensity of the influencing magnetic field need not be recorded on the magneto-optical recording medium and need not be reproduced, and the intensity of the influencing magnetic field can be easily determined. it can.

A magneto-optical disk drive according to the present invention is a magneto-optical disk drive that records a signal on a magneto-optical recording medium using laser light and a magnetic field, and reproduces a signal from the magneto-optical recording medium using laser light. A magnetic head for applying a magnetic field to the magneto-optical recording medium, a lowering means for lowering the magnetic head so as to be in contact with the magneto-optical recording medium, and a magneto-optical disc arranged on the opposite side of the magneto-optical recording medium with the magneto-optical recording medium interposed therebetween. An optical head including an objective lens for converging and irradiating the recording medium with laser light, a first magnet for performing tracking servo of the objective lens, and a second magnet for performing focus servo of the objective lens; Of the first and second magnets,
A third magnet for canceling a leakage magnetic field generated by at least one of the magnets and converging and entering the magnetic head, wherein the third magnet has an intensity determined by a magnetic field intensity detection method using a DC magnetic field. The magnetic field strength is detected by irradiating the magneto-optical recording medium with laser light,
A first step of applying a direct-current magnetic field in a first direction while changing the intensity to an irradiation point of the laser beam to reproduce a signal from the magneto-optical recording medium; and a step of reproducing the signal reproduced in the first step. A second step of detecting the number of errors, a third step of applying a DC magnetic field in a second direction opposite to the first direction to the irradiation point to reproduce a signal from the magneto-optical recording medium, A fourth step of detecting the number of errors of the reproduced signal reproduced in the step of; and a step of detecting the number of errors in the irradiation point based on a relationship between the number of errors detected in the second and fourth steps and the strength of the DC magnetic field. A fifth step of detecting a magnetic field intensity from the first or second magnet.

In the magneto-optical disk drive according to the present invention, the magnetic head is brought into contact with the magneto-optical recording medium by the lowering means. When the magneto-optical recording medium rotates, the magnetic head flies above the magneto-optical recording medium. The magnetic effect on the magneto-optical recording medium caused by the first magnet for performing tracking servo of the objective lens included in the optical head or the second magnet for performing focus servo is controlled by the third magnet. Is countered. Then, recording and / or reproduction of signals on the magneto-optical recording medium are performed while the magnetic head floats above the magneto-optical recording medium 10. The magnetic field intensity emitted from the third magnet is the same as the magnetic field intensity detected based on the relationship between the number of errors in the reproduced signal reproduced by applying a DC magnetic field to the magneto-optical recording medium and the DC magnetic field intensity. It is determined to be.

Therefore, according to the present invention, it is possible to accurately record and / or reproduce signals on the magneto-optical recording medium while keeping the magnetic head in contact with the magneto-optical recording medium.

Preferably, the third magnet of the magneto-optical disk device is arranged in the radial direction of the magneto-optical recording medium, and has a length longer than a range in which the optical head moves in the radial direction.

The optical head moves in the radial direction of the magneto-optical recording medium during a seek operation or the like, and the first head included in the optical head is moved.
And even if the position of the second magnet changes, the third magnet
Eliminate magnetic effects from the first or second magnet.

Therefore, according to the present invention, even when the optical head moves in the radial direction of the magneto-optical recording medium, signals can be accurately reproduced by removing the magnetic influence from the magnet included in the optical head.

Preferably, the third magnet of the magneto-optical disk drive is disposed on the same side of the magneto-optical recording medium as the magnetic head.

The lines of magnetic force from the first or second magnet included in the optical head are canceled by the lines of magnetic force from a third magnet arranged on the opposite side of the magneto-optical recording medium from the optical head.

Therefore, according to the present invention, even if the third magnet is arranged on the side opposite to the optical head with respect to the magneto-optical recording medium, it is possible to eliminate the magnetic influence from the magnet included in the optical head.

Further, the magneto-optical disk drive according to the present invention detects the intensity of the influence magnetic field exerted on the irradiation point of the laser beam by the servo magnet of the objective lens which irradiates the magneto-optical recording medium with the laser beam, and detects the intensity of the laser beam. A magneto-optical disk device for recording a signal on a magneto-optical recording medium using a magnetic field and / or reproducing a signal from the magneto-optical recording medium using a laser beam. A first magnetic head, lowering means for lowering the first magnetic head so as to be in contact with the magneto-optical recording medium, and a magnetic head disposed on the opposite side of the first magnetic head with the magneto-optical recording medium interposed therebetween; An optical head including an objective lens for condensing and irradiating a laser beam, a magnet, a second magnetic head for canceling an affected magnetic field, and a magnetic head for driving the first magnetic head or the second magnetic head. Comprising a de drive circuit, and a control circuit,
When detecting the intensity of the influencing magnetic field, the control circuit controls the first magnetic head to change the intensity of the direct current magnetic field in the first direction or the direct current magnetic field in the second direction opposite to the first direction to perform magneto-optical recording. Control the magnetic head drive circuit to apply to the medium,
The magnetic head drive circuit determines the strength of the influencing magnetic field based on the number of errors in the reproduction signal detected by the optical head under the application of the DC magnetic field, and applies the DC magnetic field to the magneto-optical recording medium under the control of the control circuit. , The optical head detects a signal from the magneto-optical recording medium, and at the time of reproducing the signal, the control circuit transmits a magnetic field having the same strength as the determined influence magnetic field to the second magnetic head. The magnetic head drive circuit drives the second magnetic head so as to generate a magnetic field having the same strength as the intensity of the influencing magnetic field under the control of the control circuit.

In the magneto-optical disk drive according to the present invention, when detecting the intensity of the influencing magnetic field from the servo magnet of the objective lens, the control circuit generates a direct-current magnetic field of varying intensity from the first magnetic head. Let it. The optical head reproduces a signal from the magneto-optical recording medium in a state where a DC magnetic field is applied, and detects the number of errors in the reproduced signal. This is done for DC magnetic fields in two directions.
The control circuit inputs the number of detected errors and obtains a relationship between the number of errors and the strength of the DC magnetic field. Then, the control circuit obtains a symmetrical magnetic field strength and determines the strength of the affected magnetic field.

At the time of signal reproduction, the control circuit controls the magnetic head driving circuit so that the second magnetic head generates a magnetic field having the same intensity as the determined influence magnetic field. The second magnetic head is driven according to control from the circuit, and the second magnetic head generates a magnetic field having the same intensity as the intensity of the influence magnetic field.

Therefore, according to the present invention, it is possible to generate a magnetic field for canceling the influence magnetic field based on the actually measured strength of the influence magnetic field. As a result, signals can be accurately recorded and / or reproduced on the magneto-optical recording medium.

[0031]

Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions have the same reference characters allotted, and description thereof will not be repeated.

[Embodiment 1] A magneto-optical recording medium on which signals are recorded and / or reproduced will be described with reference to FIGS.

Referring to FIG. 1, frames (Frames) as recording units are arranged at equal intervals on magneto-optical recording medium 10, and each frame has 39 segments (S).
.., S38.

The magneto-optical recording medium 10 has a planar structure in which grooves 1 and lands 2 are alternately formed in the radial direction, and the grooves 1 and lands 2 are arranged spirally or concentrically. And the length of each segment is 532
DCB (Data Channel Bit)
At the beginning of each segment, a fine clock mark (FCM: Fine Clock Mark) 3 indicating phase information of a clock for recording and reproducing data is formed. The fine clock mark 3 is formed by providing lands of a fixed length at regular intervals on the groove 1 and providing grooves of a constant length at regular intervals on the lands 2. Then, the segment S which is the head of the frame
After the fine clock mark 3, the address information (Addr) indicating the address on the magneto-optical recording medium 10 is set to 0.
ess) is preformatted by the wobbles 4 to 9 when the magneto-optical recording medium 10 is manufactured.

Wobbles 4 and 5, wobble 6 and wobble 7, and wobble 8 and wobble 9 are formed on opposite walls of groove 1 and record the same address information. Such a method of recording address information is called a one-sided staggered method. By adopting the one-sided staggered method, a tilt or the like occurs in the magneto-optical recording medium 10, and even when the laser light is deviated from the center of the groove 1 or the land 2, the information is accurately recorded. Address information can be detected.

The area where the address information is recorded and the area where the fine clock mark 3 is formed are not used as areas for recording user data. Segment S
n is the fine clock mark 3 and the user data Use
r Data n-1.

Referring to FIG. 2, a detailed configuration of the segment will be described. Each segment S constituting the frame
0, S1, S2,..., S38, the segment S0 is an address segment preformatted on the magneto-optical recording medium 10, and the segment S1 to the segment S
A data segment 38 is reserved as a recording area for user data. The segment S0 is composed of the fine clock mark area FCM of 12 DCB and the address Address of 520 DCB.
Is a 12DCB fine clock mark area FCM
, 4DCB Pre-Write, 512DCB Data, and 4DCB Post-Write.

Pre-Write indicates the writing of data. For example, the predetermined pattern "001"
The Post-Write indicates the end of the data. For example, the Post-Write indicates a predetermined pattern “1”.
100 ".

The user data area of the segment S1 is provided with a header (Header) which is a fixed pattern for performing data position confirmation during reproduction, position compensation of a reproduction clock, laser power adjustment, and the like. The fixed pattern to be recorded in the header is a pattern in which a DC component is suppressed. For example, a pattern in which a predetermined number of 2T domains are formed at intervals of 2T and a pattern in which a predetermined number of 8T domains are formed at intervals of 8T are recorded. You.

The phase compensation is performed by adjusting the sampling timing of the analog signal obtained by reproducing the 2T domain so as to coincide with the phase of the clock used for recording and reproducing the data. The 8T domain is reproduced, and the laser power is adjusted so that the ratio of the 2T domain reproduced signal strength to the 8T domain reproduced signal strength becomes 50% or more. Also, by confirming whether or not the position of the digital signal obtained by reproducing the 8T domain and binarizing the reproduced signal matches the position of the digital signal of the 8T domain predicted in advance, the position of the data at the time of reproduction can be confirmed. Do. Further, each pattern of Pre-Write, Post-Write, and Header is recorded continuously with the user data when recording the user data.

The method for detecting the magnetic field intensity according to the present invention will be described with reference to FIGS. Referring to FIG. 3, magnetic head 30 includes a core 301 and a coil 302 wound around core 301. Then, a current in a certain direction is applied to the coil 302, and the DC magnetic field DC1, DC1,
DC2 is applied to the reproducing layer 101 of the magneto-optical recording medium 10. In this case, the direction of the current flowing through the coil 302 and the current value are changed to change the DC magnetic fields DC1 and DC2 having different magnitudes.
DC2 is applied to the reproduction layer 101. In addition, DC magnetic field DC
The optical head 20 irradiates a laser beam LB from the side opposite to the application direction of the DC1 and DC2 to detect a reproduction signal. Note that, in FIG. 3, the reproduction layer 10
1 and the laser beam LB are greatly enlarged as compared with the core 301 of the magnetic head 30.

The recording layer (not shown) of the magneto-optical recording medium 10
A predetermined signal is recorded in advance by forming magnetic domains having different magnetization directions. As the predetermined signal, for example, a random data pattern of "10101010 ..." is recorded. Then, the magnetic domain formed in the recording layer is transferred to the reproducing layer 101 to reproduce a signal. In this case, a DC magnetic field in a certain direction is applied to the reproducing layer 101 of the magneto-optical recording medium 10 by applying a current in a certain direction to the coil 302, and the direction of the DC magnetic field and the direction of the magnetization transferred to the reproducing layer are different. Are the same, the magnetic domain transferred to the reproduction layer can be detected without being affected by the DC magnetic field. On the other hand, when a magnetic domain having a magnetization in a direction opposite to the direction of the DC magnetic field is transferred from the recording layer, the reproducing layer is not affected by the DC magnetic field within a range where the intensity of the DC magnetic field is not strong enough to reverse the magnetization of the reproducing layer. When a DC magnetic field strong enough to reverse the magnetization of the reproducing layer is applied, a magnetic domain having a magnetization different from the magnetization transferred to the reproducing layer is detected. Therefore, even when a random data pattern such as “10101010...” Is recorded, the data is transferred to the reproducing layer 101 by applying a DC magnetic field in a certain direction to the reproducing layer 101 of the magneto-optical recording medium 10. The magnetic field strength at which the magnetization starts to be reversed can be obtained.

Then, the intensity of the DC magnetic fields DC1 and DC2 is changed by changing the value of the current flowing through the coil 302.

When reproducing a magnetic domain having a magnetization 102,
Magnetic domains having a magnetization 102 are transferred from the recording layer to the reproducing layer 101. Then, a DC magnetic field DC <b> 1 causes a current applied to the reproducing layer 101 to flow through the coil 302. By changing the value of the current flowing through the coil 302, the reproduction layer 1 is irradiated with the laser beam LB.
01 is detected, and the number of errors in the reproduced signal for each current value is measured. Similarly, when reproducing a magnetic domain having a magnetization 103, a DC magnetic field DC2 is applied to the reproducing layer 101.
Is applied to the coil 302. Then, by changing the value of the current flowing through the coil 302, the magnetic domain transferred to the reproduction layer 101 by the laser beam LB is detected, and the number of errors in the reproduction signal for each current value is measured.

Referring to FIG. 4, the relationship between the magnetic field strength measured by the above-described method and the number of errors will be described.
A curve k1 is a measurement result for the groove 1 of the magneto-optical recording medium 10, and a curve k2 is a measurement result for the land 2 of the magneto-optical recording medium 10. Groove 1 and Land 2
In both cases, the relationship between the number of errors and the magnetic field strength has a symmetrical relationship about a certain magnetic field strength. That is, in the groove 1 and the land 2, the magnetic field intensity decreases from 20 mA around the magnetic field intensity of 20 mA.
Even if the magnetic field strength increases from A, when the deviation from 20 mA becomes almost 50 mA, the number of errors starts to increase rapidly.

Originally, if there is no influence from the servo magnet of the objective lens, the central magnetic field strength should be 0 mA according to the measurement principle described with reference to FIG. However, the center magnetic field strength in the measurement result is 20 mA.
Therefore, from the servo magnet of the objective lens 22,
The magnetic field corresponding to mA reaches the irradiation point of the laser beam. Accordingly, in the relationship diagram shown in FIG. 4, the amount of deviation of the symmetrical magnetic field strength from 0 mA is the magnetic field strength that extends from the servo magnet of the objective lens 22 to the laser beam irradiation point.

With reference to FIG. 5, a description will be given of a flowchart of a method for detecting a magnetic field intensity from the servo magnet of the objective lens 22 to the irradiation point of the laser beam. When the detection method is started, a laser beam is applied to the magneto-optical recording medium 10 by the optical head 20 (step S1). Then, a DC magnetic field in a fixed direction is applied to the magneto-optical recording medium 10 by changing the intensity from the magnetic head 30 (Step S).
2) A signal is reproduced from the magneto-optical recording medium 10 (step S3). Then, the number of errors is detected based on the reproduced signal (step S4). As a result, the number of errors in the reproduced signal for each strength of the DC magnetic field is detected.
Thereafter, it is determined whether to change the direction of the DC magnetic field (step S5). When changing the direction of the DC magnetic field, steps S2 to S4 are repeated to detect the number of errors in the reproduction signal for different directions of the DC magnetic field. When the number of errors in the reproduction signal with respect to the magnetic field strength is detected in two directions of the DC magnetic field, “No” is selected in step S5. Then, as described above from the relationship diagram between the magnetic field strength and the number of errors in the reproduction signal, the objective lens 2
The magnetic field intensity exerted on the irradiation point of the laser beam by the second servo magnet is determined (step S6). Thus, the operation of detecting the magnetic field intensity is completed.

As described above, by using the magnetic field strength detection method according to the present invention, the strength of the magnetic field affected by the servo magnet of the objective lens 22 can be easily detected.

Next, the influence of the magnetic field determined by using the magnetic field strength detection method according to the present invention is removed to remove the magneto-optical recording medium 1.
A magneto-optical disk device that records and / or reproduces a signal at 0 will be described.

Referring to FIG. 6, magneto-optical disk drive 10
0 is the optical head 20, the magnetic head 30, and the magnet 41
And The optical head 20 includes a semiconductor laser 21, and irradiates the laser beam emitted from the semiconductor laser 21 onto the magneto-optical recording medium 10 by means of an objective lens 22.
The optical head 20 is moved in the radial direction (radial direction) DR1 of the magneto-optical recording medium 10 by the rails 1A and 1B.

The magnetic head 30 is arranged on the opposite side of the optical head 20 with the magneto-optical recording medium 10 interposed therebetween. And
When recording a signal on the magneto-optical recording medium 10, the magnetic head 30 applies a magnetic field modulated by the recording signal to the magneto-optical recording medium 10. The magnetic head 30 is attached to the slider 31. The slider 31 is fixed to the support member 33 by an arm 32 made of a leaf spring. Support member 3
3 is fixed to the support member 34 by screws 35. One end of the support member 36 is fixed to the optical head 20.
And the support member 36 has an opening 37 at the other end,
Shafts 39 extend through the columnar members 38A and 38B located at both ends of the opening 37. The support member 34 has an opening 38 on the side opposite to the fixed side of the support member 33. The support member 34 has columnar members 34 at both ends of the opening 38.
A, 34B, and the columnar members 34A, 34B are located inside the columnar members 38A, 38B of the support member 36. The columnar members 34A and 34B are separated by a shaft 39 into columnar members 38.
A, 38B. And the columnar members 34A, 3
4B, a spring 42 is provided.
2 through the center.

FIG. 7 is a sectional view as seen from the direction A in FIG. The spring 42 is provided in the normal direction DR2 of the magneto-optical recording medium 10.
, The support member 34 is pressed in a direction approaching the magneto-optical recording medium 10. As a result, the support member 33, the arm 32, and the slider 31 move the magneto-optical recording medium 10
, And the magnetic head 30 is pressed against the magneto-optical recording medium 10. In this case, the arm 32
Is constituted by a leaf spring, the magnetic head 3
0 is pressed against the magneto-optical recording medium 10 with elasticity.

The screw 43 penetrates the support member 34, and one end is in contact with the member 44. The member 44 is fixed to the support member 36. The screw 43 penetrating the support member 34 by rotating the screw 43 clockwise
Becomes longer, and the distance between the support member 43 and the member 44 increases. Thus, the pressing force of the magnetic head 30 against the magneto-optical recording medium 10 is reduced. When the screw 43 is rotated counterclockwise, the length of the screw 43 penetrating the support member 34 is shortened, and the support member 43 and the member 4 are rotated.
The distance to the position 4 becomes smaller. Thereby, the magnetic head 3
The pressing force with which 0 is pressed against the magneto-optical recording medium 10 is increased. Therefore, the magnetic head 30 is moved to the magneto-optical recording medium 10.
Is controlled by a screw 43.

The magnetic head 30 is separated from the magneto-optical recording medium 10 by moving the lever 45 in the direction of the arrow 46. Then, the magneto-optical recording medium 10 is detached in this state.

In the present invention, the screw 43, the member 44, the spring 42, the support members 34 and 33, and the arm 3
2 is a magnetic head 3 so as to be in contact with the magneto-optical recording medium 10.
A lowering means for lowering 0 is configured.

Since the magnetic head 30 is connected to the optical head 20 via the slider 31, the arm 32, the supporting members 33 and 34, and the supporting member 36, the magnetic head 20
Is moved in the radial direction DR1 of the magneto-optical recording medium 10 so that the magnetic head 30 also moves to the magneto-optical recording medium 10.
Is moved in the radial direction DR1. Therefore, once the optical axis of the laser beam emitted from the optical head 20 and the center of the magnetic field applied from the magnetic head 30 are aligned once, the optical head 20 is moved to the radial direction of the magneto-optical recording medium 10 by seeking. The optical axis of the laser beam coincides with the center of the magnetic field even when the laser beam moves in the direction.

As shown in FIG. 7, before rotating the magneto-optical recording medium 10, the magnetic head 30 is in contact with the magneto-optical recording medium 10. In this state, when the magneto-optical recording medium 10 is rotated at a predetermined rotation speed in the direction of arrow 48A shown in FIG. 1, air flows into between the magnetic head 30 and the magneto-optical recording medium 10, and Is magneto-optical recording medium 1
Ascends from zero. In this case, the distance between the magnetic head 30 and the magneto-optical recording medium 10 is about 5 μm.

Therefore, when recording a signal on the magneto-optical recording medium 10, the magnetic head 30 is floated by rotating the magneto-optical recording medium 10 at a predetermined number of revolutions, and the magnetic field modulated by the recording signal is magneto-optically modulated. It is applied to the recording medium 10. When a signal is reproduced from the magneto-optical recording medium 10, laser light is emitted from the optical head 20 by rotating the magneto-optical recording medium 10 at a predetermined number of revolutions while keeping the magnetic head 30 floating. Irradiate 10 That is, the lever 45 does not separate the magnetic head 30 from the magneto-optical recording medium 10 when reproducing a signal from the magneto-optical recording medium 10.

The focus servo and tracking servo mechanisms of the objective lens 22 will be described with reference to FIG. A magnet 24 is arranged on one surface of the support member 23, and a coil 25 is wound around the support member 23 and the magnet 24. A magnet 26 is arranged on one surface of the support member 28, a coil 27 is arranged so as to face the magnet 26, and the same coil (not shown) as the coil 27 is arranged beside the coil 27. I have. The objective lens 22 is provided on the opposite side of the surface of the support member 28 on which the magnet 26 is disposed. When a current is applied to the coil 25, the coil 25 receives a Lorentz force from the magnet 24 in a normal direction DR2 (also referred to as a “focus direction”) of the magneto-optical recording medium 10, and the coil 25 moves in the focus direction DR2. Thereby, the objective lens 22 can move in the focus direction DR2. In addition, by supplying a current to the coil 27 and the coil not shown, the coil 27 and the coil not shown
6, the objective lens 22 can move in the tracking direction DR1 of the magneto-optical recording medium 10 by receiving the Lorentz force in the radial direction DR1 of the magneto-optical recording medium 10 (also referred to as the “tracking direction”).

The optical head 20 shown in FIGS.
Magnets 24 and 26 and coils 25 and 27 are included.
2 focus servo and tracking servo are performed. As described above, when trying to reproduce a signal using laser light in a state where the magnetic head 30 is in contact with the magneto-optical recording medium 10, the lines of magnetic force from the magnets 24 and 26 cause the core (ferrite) of the magnetic head 30. The magnetic layer concentrated on the core of the magnetic head 30 affects the magnetic layer of the magneto-optical recording medium 10 facing the magnetic head 30. As a result, when a magnetic domain is transferred from the recording layer constituting the magnetic layer of the magneto-optical recording medium 10 to the reproducing layer via the non-magnetic layer, the transferred magnetic domain in the reproducing layer is formed by magnetic field lines concentrated on the core of the magnetic head 30. to be influenced. As a result, the polarization plane of the laser light is originally rotated for the magnetization different from the magnetization of the magnetic domain transferred to the reproduction layer, and the rotation of the polarization plane of the original laser light cannot be detected.

Therefore, referring again to FIG.
Is attached to the lid member 40. FIG. 6 is a perspective view showing a state where the lid member 40 is opened. The lid member 40 is
Usually, it is made of plastic or the like.

Referring to FIG. 9, magnet 41 has a plate shape, and lines of magnetic force are emitted from flat surface 410, and lines of magnetic force are incident on flat surface 411. That is, the flat surface 410
Emits the line of magnetic force φ1, and the flat surface 411 receives the line of magnetic force φ1.

FIG. 10 shows the cover member 40 of FIG.
FIG. 7 is a perspective view in a state of being moved in the direction of FIG.
The cover member 40 is omitted to clarify the arrangement position of the magnet 41 with respect to the optical head 20, the magnetic head 30, and the like. The magnet 41 is disposed on the side of the magnetic head 30 with respect to the magneto-optical recording medium 10 so that the longitudinal direction thereof is in the radial direction DR1 of the magneto-optical recording medium 10. Then, the line of magnetic force φ emitted from the flat surface 410 of the magnet 41
1, the magnets 24, 26 included in the optical head 20
And the magnetic lines of force from the magnets 24 and 26 do not magnetically affect the magnetic layer of the magneto-optical recording medium 10.

FIG. 11 is a sectional view of the magnetic head 30 shown in FIG.
FIG. 4 is a plan view as viewed from the side of a magnet 41. The magnet 41 is
Instead of being arranged directly above the magnetic head 30, it is arranged at a position shifted in the direction of the rail 1 </ b> A from the arrangement position of the magnetic head 30. The reason will be described later.

FIG. 12 is a sectional view of FIG. 10 as viewed from the rail 1A side. The magneto-optical recording medium 10 is placed on a turntable 111. Spindle motor 110
Rotates the magneto-optical recording medium 10 at a predetermined rotation speed by rotating the turntable 111 at a predetermined rotation speed. The objective lens 22 is provided at a position facing the magnetic head 30 with the magneto-optical recording medium 10 interposed therebetween. The longitudinal length of the magnet 41 is longer than the recording area 10R of the magneto-optical recording medium 10. This is because the optical head 20 seeks along the rails 1A and 1B in the radial direction DR1 of the magneto-optical recording medium 10, and accordingly, the magnets 24 and 26 and the magnetic head 30 included in the optical head 20 move to the magneto-optical recording medium 10. Moving in the radial direction DR1 of the magnet 2
4 and 26 are for canceling the magnetic influence on the magnetic layer of the magneto-optical recording medium 10. Thereby, the magnet 2
, 26 and the magnetic head 30
Irrespective of the position in the recording area 10R, the magnetic effect of the magnets 24 and 26 on the magnetic layer of the magneto-optical recording medium 10 can be canceled to reproduce a signal.

On the flat surface 411 side of the magnet 41, an iron plate 47 is attached. And the iron plate 47 is installed in the lid member 40. Thereby, the iron plate 47 in contact with the flat surface 411 of the magnet 41 becomes magnetic. That is, as shown in FIG. 13, the flat surface 410 of the magnet 41 is N
Assuming that the pole and the flat surface 411 are S poles, the flat surface 471 of the iron plate 47 in contact with the flat surface 411 of the magnet 41 becomes an N pole and the flat surface 472 becomes an S pole. And the flat surface 471
Emits a line of magnetic force φ2.
1 is added to the magnetic force line φ1 emitted from the flat surface 410. As a result, the magnet 41 emits the lines of magnetic force φ1 + φ2. The lines of magnetic force φ1 + φ2 are used to cancel lines of magnetic force from the magnets 24 and 26 included in the optical head 20.

The iron plate 47 has a flat surface
To the cover member 4 via the iron plate 47.
When it is not attached to 0, the line of magnetic force φ1 penetrates the lid member 40 and enters the magnet 41. Then, the magneto-optical recording medium placed near the lid member 40 is magnetically affected,
The recorded signal may be erased. Therefore, the magnet 41 is attached to the lid member 40 via the iron plate 47 in order to reduce the lines of magnetic force that penetrate the lid member 40 and enter the magnet 41.

That is, by selecting a material in which the magnetic flux density of the magnetic flux line φ2 is smaller than the magnetic flux density of the magnetic flux line φ1 as the iron plate 47, the magnet 41 can be directly connected to the lid member 40.
The magnetic influence on the outside can be reduced as compared with the case where the device is mounted on a computer. Further, as described above, since the iron plate 47 emits the magnetic field lines φ2 from the flat surface 471 in the direction of the magnetic head 30, the magnet 41 can have a smaller magnetic flux density than when the iron plate 47 is not provided.

Specifically, when the iron plate 47 is not provided, the magnetic flux density of the magnet 41 required to cancel the lines of magnetic force from the magnets 24 and 26 included in the optical head 20 is 5250 to 5250.
Although it was 5650 gauss, the magnetic flux density of the magnet 41 could be halved to about 2600 gauss by providing the iron plate 47. The leakage magnetic field from the magnet 41 measured outside the lid member 40 was about 360 Gauss when the iron plate 47 was not provided, but by providing the iron plate 47, the leakage magnetic field was reduced to about 50 Gauss or less. 1/6 to 1
/ 7.

As described above, by installing the magnet 41 on the cover member 40 via the iron plate 47, the magnets 24, 26
In addition to reducing the magnetic flux density of the magnet 41 necessary for canceling the influence of the lines of magnetic force from the magnet 41, the leakage magnetic field from the magnet 41 to the outside can be reduced. In addition, as the iron plate 47,
A 0.2 mm thick tin plate was used.

FIG. 14 is a diagram showing a case where A in FIG. 6 and FIG.
It is sectional drawing seen from the direction. Magnet 41 and iron plate 47
Are arranged at positions shifted from the magnetic head 30 toward the rail 1A. The reason will be described with reference to FIG. Magnets 24 and 26 included in optical head 20 and magnetic head 3
0, a magnetic field Hex1 exists in a direction from the magnets 24 and 26 to the magnetic head 30. This magnetic field Hex1
Is not a magnetic field perpendicularly incident on the magnetic head 30 but a magnetic field incident at an angle θ from the direction of the magnets 24 and 26 with respect to the normal direction of the magnetic head 30. Therefore, the magnet 41
In order to cancel the magnetic field Hex1 by the magnetic field Hex2 emitted from the magnetic head 30, the magnetic field Hex2 needs to be incident on the magnetic head 30 at an angle θ with respect to the normal direction of the magnetic head 30. For such a reason, the magnet 41 is
Not directly above, but at a position displaced in the direction of the rail 1A from the arrangement position of the magnetic head 30. The magnetic field He
x2 is a magnetic field having the same magnitude as the magnetic field Hex1 but in the opposite direction.

The distance L between the magnet 41 and the magneto-optical recording medium 10
1 is 6.38 mm, and the magnet 41 and the magnetic head 30
Is 6.7 mm. as a result,
The magnetic field Hex2 from the magnet 41 is incident on the magnetic head 30 at an angle θ = 53.9 degrees.

Referring to FIG. 16, the effect of magnet 41 will be described. FIG. 16 is a diagram showing the relationship between the number of errors measured by the magnetic field strength detection method according to the present invention and the DC magnetic field strength. The horizontal axis is the MH current, which corresponds to the strength of the DC magnetic field. The vertical axis represents the number of errors in the reproduced signal detected from the magneto-optical recording medium.

A curve k3 indicates a case where the magnet 41 is not installed, and a curve k4 indicates a case where the magnet 41 is installed. A DC magnetic field DC1 is applied to the reproducing layer 101 by flowing a positive MH current through the coil 302, and a DC magnetic field D1 is generated by flowing a negative MH current through the coil 302.
It is assumed that C2 is applied to the reproduction layer 101.

First, the case where the magnet 41 is not installed will be described. A magnetic domain having a magnetization 102 is transferred to the reproducing layer 101, and a DC magnetic field DC having a changed intensity is applied to the reproducing layer 101.
1 is applied. Then, when the MH current is in the range of 0 to 40 mA, the number of errors hardly changes, and the MH current becomes 50 mA.
, The number of errors starts to increase, and when the MH current becomes 50 mA or more, the number of errors rapidly increases. On the other hand, the reproduction layer 10
1 is transferred to the reproducing layer 101.
A DC magnetic field DC2 of which the intensity has been changed is applied. Then, the number of errors hardly changes when the MH current is in the range of -10 to 0 mA, and when the MH current becomes -10 mA or less, that is, 10 mA or more in absolute value, the number of errors sharply increases. The number of errors increases rapidly when the strength of the DC magnetic fields DC1 and DC2 increases, because the magnetic domain transferred to the reproduction layer 101 can have its magnetization direction reversed by the DC magnetic fields DC1 and DC2.

As a result, when the magnet 41 is not installed, the relationship between the number of errors and the MH current is as shown by a curve k3.
The H current becomes a symmetrical curve centered on +20 mA. Originally, unless a magnetic field other than the DC magnetic fields DC1 and DC2 is applied to the region of the reproduction layer 101 where the magnetic domains are transferred, the MH current should be a symmetrical curve centering on 0 mA. However, based on the fact that the actually measured center value is shifted by 20 mA in the plus direction,
That is, a magnetic field in the same direction as 02 is applied to the region of the reproduction layer 101 where the magnetic domain is transferred. That is, the magnetic field from the magnets 24 and 26 included in the optical head 20 is applied to the reproducing layer 1.
01 is applied to the area to be transferred.

On the other hand, when the magnet 41 is provided, the MH current becomes a left-right symmetric curve k2 centering on 0 mA. That is, the magnetic domain having the magnetization 102 is transferred to the reproducing layer 101, and the DC magnetic field DC 1 having the changed intensity is applied to the reproducing layer 101.
Is applied. Then, when the MH current is in the range of 0 to 20 mA, the number of errors hardly changes, and when the MH current exceeds 20 mA, the number of errors rapidly increases. On the other hand, the magnetic domain having the magnetization 103 is transferred to the reproducing layer 101 and the reproducing layer 1
A DC magnetic field DC2 whose intensity has been changed to 01 is applied. Then, when the MH current is in the range of -20 to 0 mA, the number of errors hardly changes. When the MH current becomes -20 mA or less, that is, when the absolute value is 20 mA or more, the error number sharply increases. The reason why the number of errors increases rapidly when the strength of the DC magnetic fields DC1 and DC2 increases is the same as the reason described above.

As a result, a curve k4 is obtained which is symmetrical with respect to the MH current of 0 mA. Therefore, by installing the magnet 41, the magnet 2 included in the optical head 20 is
The influence of the magnetic field from 4, 26 can be eliminated.

In the above, the magnetic field He directed from the magnets 24 and 26 included in the optical head 20 to the magnetic head 30
Although the magnet for generating the magnetic field Hex2 for canceling x1 has been described as being installed on the magnetic head 30 side with respect to the magneto-optical recording medium 10, the present invention is not limited to this.
A magnet that generates a magnetic field Hex2 for canceling ex1
It may be installed on the optical head 20 side with respect to the magneto-optical recording medium 10.

FIG. 17 is a sectional view when a magnet for generating a magnetic field Hex2 for canceling the magnetic field Hex1 is installed on the optical head 20 side with respect to the magneto-optical recording medium 10.
FIG. 8 corresponds to FIG. 7. The magnet 41A is connected to the optical head 2
0 is set below. The longitudinal length of the magnet 41A is longer than the recording area 10R of the magneto-optical recording medium 10.
The longitudinal direction of the magnet 41A is the magneto-optical recording medium 1.
It is arranged so as to be 0 in the radial direction DR1. Thereby, the seek of the optical head 20 causes the magnets 24 and 26 included in the optical head 20 and the magnetic head 3.
0 moves in the radial direction DR 1 of the magneto-optical recording medium 10, the magnet 41 A moves the magnet head 3 from the magnets 24 and 26.
The magnetic field Hex1 to 0 can be canceled.

Referring to FIG. 18, even when magnet 41A is arranged below optical head 20, magnet 41A is arranged not directly below magnetic head 30 but at a position shifted from magnetic head 30 toward rail 1B. . In FIG. 18, the direction perpendicular to the paper is the radial direction DR1 of the magneto-optical recording medium 10.
It is.

Referring to FIG. 19, the reason why the magnet 41A is arranged at a position shifted from the magnetic head 30 toward the rail 1B will be described. As described above, the optical head 20
Between the magnets 24, 26 and the magnetic head 30,
A magnetic field Hex1 exists in a direction from the magnets 24 and 26 to the magnetic head 30. This magnetic field Hex1 is generated by the magnets 24,
26 to the direction normal to the magnetic head 30
Is the incident magnetic field. Therefore, in order to cancel the magnetic field Hex1 by the magnetic field Hex2 emitted from the magnet 41A, the magnetic field Hex2 is
In the direction toward the magnet 41A, it is necessary to enter the magnet 41A at an angle θ with respect to the normal direction of the magnet 41A. For such a reason, the magnet 41A is installed not at the position directly below the magnetic head 30 but at a position shifted in the direction of the rail 1B from the arrangement position of the magnetic head 30.

Referring to FIG. 20, magneto-optical disk drive 1
00 is the spindle motor 110 and the optical head 20
, A magnetic head 30, a magnet 41, a fine clock mark detection circuit (FCM detection circuit) 120, a PLL circuit 130, an address detection circuit 140, and a BPF 150.
, An AD converter 160, a waveform equalization circuit 170, a Viterbi decoding circuit 180, an unformat circuit 190,
A data demodulation circuit 200, a BCH decoder 210, a header detection circuit 220, a controller 230, a timing generation circuit 240, a BCH encoder 250, a data modulation circuit 260, a format circuit 270, a magnetic head drive circuit 280, A laser drive circuit 290.

The magnet 41 prevents the magnetic field emitted from the magnets 24 and 26 included in the optical head 20 from being concentrated on the magnetic head 30 as described above. The spindle motor 110 rotates the magneto-optical recording medium 10 at a predetermined rotation speed. The optical head 20 irradiates the magneto-optical recording medium 10 with laser light and detects the reflected light. The FCM detection circuit 120 detects that the optical head 20 detects a fine clock mark detection signal indicating the position of the fine clock mark 3 on the magneto-optical recording medium 10, and outputs the detected fine clock mark detection signal to the PLL circuit 130 and the timing generation circuit. Output to 240.

The PLL circuit 130 generates a clock based on the fine clock mark detection signal output from the FCM detection circuit 120, and divides the generated clock into an address detection circuit 140, an AD converter 160, and a waveform equalizer. Circuit 170, Viterbi decoding circuit 180, unformat circuit 190, data demodulation circuit 200, controller 230, timing generation circuit 240, data modulation circuit 2
60 and the format circuit 270.

The address detection circuit 140 inputs an address signal detected by the optical head 20 from the segment S0 of the magneto-optical recording medium 10 by the tangential push-pull method, and synchronizes with the clock input from the PLL circuit 130. The address information is detected, and an address detection signal indicating that the address information has been detected is generated at the last position of the address information. Then, it outputs the detected address information to the controller 230, and outputs the generated address detection signal to the header detection circuit 220 and the timing generation circuit 240.

The BPF 150 is a magneto-optical recording medium 1
The high frequency and the low frequency of the reproduced signal reproduced from 0 are removed. A
The D converter 160 converts the reproduced signal from an analog signal to a digital signal in synchronization with the clock from the PLL circuit 130.

The waveform equalizing circuit 170 includes a PLL circuit 130
The PR (1,1) waveform equalization is performed on the reproduced signal converted into the digital signal in synchronization with the clock from the CPU. That is, the data before and after the detection signal are equalized so as to cause one-to-one waveform interference.

The Viterbi decoding circuit 180 includes a PLL circuit 13
The reproduction signal is converted from multi-valued data to binary data in synchronization with the clock from 0, and the converted reproduction signal is output to the unformat circuit 190 and the header detection circuit 220.

The unformat circuit 190 pre-writes (Pre-Write) and post-writes (Post-Write) recorded in the user data area of the magneto-optical recording medium 10 based on the timing signal input from the header detection circuit 220. , And the header (Heade
r) is removed.

The data demodulation circuit 200 includes a PLL circuit 13
An unformatted reproduction signal is input in synchronization with a clock from 0, and demodulation is performed to resolve digital modulation performed during recording.

[0092] The BCH decoder 210 corrects the error of the demodulated reproduced signal and outputs it as reproduced data.
The header detection circuit 220 detects the position of the header included in the reproduction signal based on the address information input from the controller 230 and the address detection signal input from the address detection circuit 140, and synchronizes with the clock from the PLL circuit 130. Pre-write (Pre-W
write) and a header (Header) timing signal. Then, the generated header (Heade
The timing signal of r) is output to the unformat circuit 190 and the data demodulation circuit 200.

The controller 230 receives the address information detected by the address detection circuit 140, controls a servo mechanism (not shown) based on the address information, and causes the optical head 20 to access a desired position. Further, the controller 230 outputs the address information to the header detection circuit 220 in synchronization with the clock from the PLL circuit 130, and controls the timing generation circuit 240.

The timing generation circuit 240 controls the FCM detection circuit 120 based on the control from the controller 230.
The timing is generated in synchronization with the clock input from the PLL circuit 130 on the basis of the fine clock mark detection signal input from the PLL and the address final position input from the address detection circuit 140, and the generated timing signal is formatted. The signal is output to the circuit 270, the magnetic head driving circuit 280, and the laser driving circuit 290.

The BCH encoder 250 adds an error correction code to recording data. The data modulation circuit 260 modulates recording data into a predetermined format. Format circuit 2
Reference numeral 70 denotes a pre-write (Pre-Write) for the recording data in synchronization with the clock from the PLL circuit 130 and based on the timing signal from the timing generation circuit 240.
e), a header (Header), and a post-write (Post-Write) are added to format the recording data so as to match the user data area, and the formatted data is output to the magnetic head drive circuit 280.

The magnetic head drive circuit 280 drives the magnetic head 30 in synchronization with each timing of the timing signal from the timing generation circuit 240 and based on the output from the format circuit 270.

The laser drive circuit 290 drives the semiconductor laser 21 in the optical head 20 based on a timing signal from the timing generation circuit 240.

The magnetic head 30 includes a magnetic head driving circuit 2
A magnetic field, which is driven by 80 and modulated by the recording data or data pattern, is applied to the magneto-optical recording medium 10.

The operation of recording data on the magneto-optical recording medium 10 using the magneto-optical disk device 100 will be described.
When the magneto-optical recording medium 10 is mounted on the magneto-optical disk device 100, the controller 230
A servo mechanism (not shown) controls the laser 10 to rotate at a predetermined rotation speed, and controls the laser drive circuit 290 via the timing generation circuit 240 so that laser light of a predetermined intensity is emitted from the optical head 20. I do.

Then, the servo mechanism (not shown)
The spindle motor 110 is rotated at a predetermined rotation speed, and the spindle motor 110 rotates the magneto-optical recording medium 10 at a predetermined rotation speed. Before the magneto-optical recording medium 10 rotates at a predetermined rotation speed, the magnetic head 30
However, the magnetic head 30 floats when the magneto-optical recording medium 10 rotates at a predetermined rotation speed. The optical head 20 irradiates the laser beam of a predetermined intensity with the objective lens 22 onto the magneto-optical recording medium 10 and detects the reflected light. Then, the optical head 20 outputs a focus error signal and a tracking error signal to a servo mechanism (not shown), and the servo mechanism outputs the focus error signal and the tracking error signal based on the focus error signal and the tracking error signal.
The focus servo and the tracking servo of the objective lens 22 of the optical head 20 are turned on.

Thereafter, the optical head 20 detects an optical signal detected from the magneto-optical recording medium 10 by the radial push-pull method, and outputs the detected optical signal to the FCM detection circuit 12.
Output to 0. The FCM detection circuit 120 detects a fine clock mark detection signal from the input optical signal, and outputs the detected fine clock mark detection signal to the PLL circuit 130 and the timing generation circuit 240.
The PLL circuit 130 generates a clock based on the fine clock mark detection signal, and uses the generated clock as an address detection circuit 140, an AD converter 160, a waveform equalization circuit 170, a Viterbi decoding circuit 180, an unformat circuit 190, Data demodulation circuit 200, controller 2
30, timing generation circuit 240, data modulation circuit 26
0 and output to the format circuit 270.

The address detection circuit 140 inputs an address signal detected by the optical head 20 from the segment S0 of the magneto-optical recording medium 10 by the tangential push-pull method, and synchronizes with the clock input from the PLL circuit 130. The address information is detected, and an address detection signal indicating that the address information has been detected is generated at the last position of the address information. Then, it outputs the detected address information to the controller 230, and outputs the generated address detection signal to the header detection circuit 220 and the timing generation circuit 240.

On the other hand, the BCH encoder 250 adds an error correction code to the recording data,
Is synchronized with the clock from the PLL circuit 130.
The recording data from the encoder 250 is modulated into a predetermined format. Then, the data modulation circuit 260 outputs the modulated recording data to the format circuit 270.

When the address signal input from the address detection circuit 140 specifies the address of the data area of the magneto-optical recording medium 10, the controller 230 generates a timing signal for generating a recording signal suitable for the format of the data area. Is generated by the timing generation circuit 2
40 is controlled. Then, the timing generation circuit 240
Generates a timing signal synchronized with the clock based on the input fine clock mark detection signal and address signal, and sends the generated timing signal to the format circuit 270, the magnetic head drive circuit 280, and the laser drive circuit 290. Output.

The format circuit 270 formats the recording signal input from the data modulation circuit 260 so as to conform to the format of the data area based on the timing signal, and outputs it to the magnetic head drive circuit 280.
Then, the magnetic head drive circuit 280 drives the magnetic head 30 so as to generate a magnetic field modulated by the recording signal in synchronization with the timing signal. On the other hand, the laser drive circuit 290 synchronizes the optical head 20 with the timing signal.
The semiconductor laser 21 is driven, and the optical head 20 focuses and irradiates the laser beam on the magneto-optical recording medium 10 by the objective lens 22. Then, the magnetic head 30 applies a magnetic field modulated by the recording signal to the magneto-optical recording medium 10.
Thus, the recording data is recorded on the magneto-optical recording medium 10.

Next, the operation of reproducing a signal from the magneto-optical recording medium 10 using the magneto-optical disk device 100 will be described. The magneto-optical recording medium 10 is a magneto-optical disk device 100
, The magnetic head 30 is levitated, and the objective lens 2
The operation until the focus servo and tracking servo of No. 2 are performed is the same as the signal recording operation.

Thereafter, the optical head 20 detects an optical signal detected from the magneto-optical recording medium 10 by the radial push-pull method, and outputs the detected optical signal to the FCM detection circuit 12.
Output to 0. The FCM detection circuit 120 detects a fine clock mark detection signal from the input optical signal, and outputs the detected fine clock mark detection signal to the PLL circuit 130 and the timing generation circuit 240.
The PLL circuit 130 generates a clock based on the fine clock mark detection signal, and uses the generated clock as an address detection circuit 140, an AD converter 160, a waveform equalization circuit 170, a Viterbi decoding circuit 180, an unformat circuit 190, Data demodulation circuit 200, controller 2
30, timing generation circuit 240, data modulation circuit 26
0 and output to the format circuit 270.

The address detection circuit 140 inputs an address signal detected by the optical head 20 from the segment S0 of the magneto-optical recording medium 10 by the tangential push-pull method, and synchronizes with the clock input from the PLL circuit 130. The address information is detected, and an address detection signal indicating that the address information has been detected is generated at the last position of the address information. Then, it outputs the detected address information to the controller 230, and outputs the generated address detection signal to the header detection circuit 220 and the timing generation circuit 240.

The header detection circuit 220 detects the position of the header included in the reproduction signal based on the address information input from the controller 230 and the address detection signal input from the address detection circuit 140, and
Pre-write (Pre-Write) and header (Hea) are performed from the reproduced signal in synchronization with the clock from L circuit 130.
der). Then, it outputs the generated timing signal of the header to the unformat circuit 190 and the data demodulation circuit 200.

On the other hand, the optical head 20 outputs the detected reproduced signal to the BPF 150, and the BPF 150 cuts the high band and the low band of the reproduced signal. AD converter 160
Is synchronized with the clock from the PLL circuit 130,
The reproduction signal output from F150 is converted from an analog signal to a digital signal.

The waveform equalization circuit 170 performs PR (1, 1) waveform equalization on the reproduced signal converted into a digital signal in synchronization with the clock from the PLL circuit 130.
That is, the data before and after the detection signal are equalized so as to cause one-to-one waveform interference.

After that, the Viterbi decoding circuit 180
In synchronization with the clock from the circuit 130, the reproduced signal whose waveform has been equalized is converted from multi-valued data into binary data, and the converted reproduced signal is output to the unformat circuit 190 and the header detection circuit 220.

Then, the header detection circuit 220 detects the position of the header included in the reproduction signal based on the address information input from the controller 230 and the address detection signal input from the address detection circuit 140,
The pre-write (Pre-Write) and the header (H
header). Then, it outputs the generated timing signal of the header to the unformat circuit 190 and the data demodulation circuit 200.

The unformat circuit 190 pre-writes (Pre-Write) and post-writes (Post-Write) recorded in the user data area of the magneto-optical recording medium 10 based on the timing signal input from the header detection circuit 220. , And the header (Heade
r) is removed.

The data demodulation circuit 200 inputs an unformatted reproduction signal in synchronization with the clock from the PLL circuit 130, and performs demodulation for canceling digital modulation performed at the time of recording. Then, the BCH decoder 210 performs error correction on the demodulated reproduced signal,
Output as playback data. Thus, the operation of reproducing the signal from the magneto-optical recording medium 10 ends. When reproducing a signal, the magnetic head 30 moves the magneto-optical recording medium 1.
If the magnetic layer of the magneto-optical recording medium 10 is magnetically affected by the magnets 24 and 26 included in the optical head 20 unless the magnet 41 is installed, the signal cannot be accurately reproduced. However, since the magnetic influence from the magnets 24 and 26 can be canceled by the magnet 41, the signal can be accurately reproduced.

According to the first embodiment, in the direction of two DC magnetic fields, the number of errors in the reproduced signal detected by applying the DC magnetic field of which the intensity is changed to the reproducing layer of the magneto-optical recording medium, and the intensity of the DC magnetic field. Is obtained, it is possible to actually measure the intensity of the influence magnetic field from the magnet that performs the servo of the objective lens. Also, since the intensity of the magnetic field affected by the servo magnet of the objective lens is actually measured, and a magnet is provided to eliminate the influence of the magnetic field and the signal is reproduced from the magneto-optical recording medium, the magnet for the servo of the objective lens is used. This can prevent the characteristics of the reproduced signal from deteriorating.

[Second Embodiment] In the second embodiment, the detection method for detecting the intensity of the influence magnetic field from the servo magnet of the objective lens 22 can be the same as the detection method in the first embodiment.

Referring to FIG. 21, a magneto-optical disk device 400 according to the second embodiment adds a magnetic head 300 to magneto-optical disk device 100 shown in FIG. 20, and BCH decoder 210 outputs an error rate of a reproduced signal, that is, , The number of errors is output to the controller 230.
The rest is the same as the magneto-optical disk device 100.

The magnetic head 300 is driven by a magnetic head drive circuit 280. Magneto-optical disk drive 400
Is a magneto-optical disk drive capable of recording and / or reproducing signals by measuring the intensity of the magnetic field affected by the servo magnet of the objective lens 22 and removing the influence of the magnetic field of the measured intensity. The intensity of the influencing magnetic field from the servo magnet of the objective lens 22 is detected according to the same detection method as in the first embodiment.

The controller 230 controls the magnetic head drive circuit 280 via the timing generation circuit 240 so as to apply a DC magnetic field whose intensity is changed from the magnetic head 30 to the magneto-optical recording medium 10. Controls the laser drive circuit 290 so that the laser light having a predetermined intensity is irradiated on the magneto-optical recording medium 10. The magnetic head drive circuit 280 drives the magnetic head 30 so as to emit a DC magnetic field whose intensity is changed under the control of the controller 230, and the magnetic head 30 applies the DC magnetic field whose intensity is changed to the magneto-optical recording medium 10 Is applied. Also,
The laser light drive circuit 290 drives the semiconductor laser 21 in the optical head 20, and the optical head 20 irradiates the magneto-optical recording medium 10 with a laser beam having a predetermined intensity. Then, as described in the first embodiment, the magneto-optical signal detected for each intensity of the DC magnetic field is converted into a BPF 150, an AD converter 160, a waveform equalizing circuit 170, a Viterbi decoding circuit 18
0, unformat circuit 190, data demodulation circuit 20
0, and a reproduction process is performed by the BCH decoder 210. Then, the BCH decoder 210 outputs the error rate of the reproduction signal, that is, the number of errors, to the controller 230.

Then, the controller 230 sets the BC
Based on the relationship between the DC magnetic field strength and the error number of the reproduction signal based on the number of errors input from the H decoder 210, the center magnetic field strength at the time of left-right symmetry is determined, and the strength of the affected magnetic field is determined. . And the controller 230
Controls the magnetic head drive circuit 280 via the timing generation circuit 240 so as to generate a magnetic field for canceling the influence magnetic field based on the determined strength of the influence magnetic field.
The magnetic head drive circuit 280 drives the magnetic head 300 under the control of the controller 230, and the magnetic head 300 generates a magnetic field for canceling the influence magnetic field.

The magneto-optical disk device 400 performs signal recording and / or reproduction on the magneto-optical recording medium 10 with the magnetic head 300 removing the influence magnetic field from the servo magnet of the objective lens 22.

The operation of recording a signal on the magneto-optical recording medium 10 and the operation of reproducing the signal from the magneto-optical recording medium 10 in the magneto-optical disk device 400 are the same as those described in the first embodiment.

According to the second embodiment, the magneto-optical disk device actually measures the intensity of the influence magnetic field from the servo magnet of the objective lens, and generates a magnetic field for removing the influence magnetic field based on the result of the measurement. Therefore, the recording and / or reproduction of the signal from the magneto-optical recording medium can be performed accurately.

The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description of the embodiments, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a data format of a magneto-optical recording medium on which data is recorded and reproduced by a magneto-optical disk device.

FIG. 2 is a diagram for explaining a segment structure of the magneto-optical recording medium shown in FIG.

FIG. 3 is a diagram for explaining a detection method for detecting the intensity of an influence magnetic field from a servo magnet of an objective lens.

FIG. 4 is a diagram illustrating the relationship between the number of errors in a reproduction signal and the intensity of a DC magnetic field.

FIG. 5 is a flowchart illustrating an operation of detecting the intensity of an influence magnetic field from a servo magnet of the objective lens according to the present invention.

FIG. 6 is a perspective view showing a magnetic head and an optical head in the magneto-optical disk device according to the embodiment of the present invention;

FIG. 7 is a cross-sectional view as viewed from a direction A in FIG.

8 is a perspective view of an objective lens included in the optical head of the magneto-optical disk device shown in FIG. 6, and an actuator that performs focus servo and tracking servo of the objective lens.

FIG. 9 is a perspective view illustrating a magnet of the magneto-optical disk device shown in FIG. 6;

FIG. 10 is a perspective view in a state where a lid member is closed in FIG. 6;

FIG. 11 is a plan view seen from the magnetic head side in FIG.

FIG. 12 is a cross-sectional view as viewed from the semiconductor laser side in FIG.

FIG. 13 is a perspective view for explaining a leakage magnetic field prevention material for preventing a magnetic field from leaking outside.

FIG. 14 is a cross-sectional view seen from the direction A in FIGS. 6 and 10;

FIG. 15 is a cross-sectional view for explaining an arrangement position of a magnet of the magneto-optical disk device shown in FIG.

16 is a diagram illustrating the relationship between the number of errors and the MH current for describing the effect of the magnet of the magneto-optical disk device illustrated in FIG.

17 is a cross-sectional view illustrating another arrangement position of the magnets of the magneto-optical disk device shown in FIG.

FIG. 18 is a sectional view illustrating another arrangement position of the magnet of the magneto-optical disk device shown in FIG.

19 is a cross-sectional view illustrating another arrangement position of the magnet of the magneto-optical disk device shown in FIG.

FIG. 20 is a schematic block diagram of a magneto-optical disk device according to the first embodiment.

FIG. 21 is a schematic block diagram of a magneto-optical disk device according to a second embodiment.

[Explanation of symbols]

1 groove, 1A, 1B rail, 2 lands, 3
Fine clock mark, 4-9 wobbles, 10 magneto-optical recording medium, 10R recording area, 20 optical heads,
21 semiconductor laser, 22 objective lens, 23, 28,
33, 34, 36 support members, 24, 26, 41, 41
A magnet, 25 to 27 coils, 30,300 magnetic head, 31 slider, 32 arms, 35, 43
Screw, 34A, 34B, 38A, 38B Column member, 3
7, 38 opening, 39 axis, 40 lid member, 42 spring, 44 member, 45 lever, 46, 48A, 48B
Arrow, 47 iron plate, 100, 400 magneto-optical disk drive, 101 reproducing layer, 102, 103 magnetization, 110
Spindle motor, 111 turntable, 120
FCM detection circuit, 130 PLL circuit, 140 address detection circuit, 150 BPF, 160 AD converter, 1
70 waveform equalization circuit, 180 Viterbi decoding circuit, 190
Unformat circuit, 200 data demodulation circuit, 2
10 BCH decoder, 220 header detection circuit, 23
0 controller, 240 timing generation circuit, 25
0 BCH encoder, 260 data modulation circuit, 27
0 format circuit, 280 magnetic head drive circuit, 2
90 Laser drive circuit, 301 core, 302 coil, 410, 411, 471, 472 Flat surface.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 5/02 G11B 5/02 T (72) Inventor Seiji Kajiyama 2-5-5 Keihanhondori, Moriguchi-shi, Osaka No. 5 Inside Sanyo Electric Co., Ltd. (72) Inventor Seiichiro Takahashi 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term inside Sanyo Electric Co., Ltd. 5D075 AA03 CF01 CF03 CF10 5D091 AA08 CC17 FF05 HH06

Claims (7)

[Claims] 1. A magnetic field intensity detecting method for detecting a magnetic field intensity applied to a laser light irradiation point by a servo magnet of an objective lens for irradiating a laser beam to a magneto-optical recording medium. A first step of irradiating a laser beam and applying a direct current magnetic field in a first direction while changing the intensity at the irradiation point to reproduce a signal from the magneto-optical recording medium; and A second step of detecting the number of errors in the reproduced reproduction signal; and applying a DC magnetic field in a second direction opposite to the first direction to the irradiation point to reproduce the signal from the magneto-optical recording medium. A third step of detecting the number of errors in the reproduced signal reproduced in the third step; and an error detected in the second and fourth steps. On the basis of the relationship between the intensity of the DC magnetic field, the detection method of the magnetic field strength and a fifth step of detecting the impact strength of the magnetic field the magnet on the irradiation point and. 2. The method according to claim 1, wherein, in the relationship between the detected number of errors and the strength of the DC magnetic field, when the strength of the DC magnetic field is increased in the first direction, the first magnetic field strength at which the number of errors starts increasing And when the intensity of the DC magnetic field is increased in the second direction, a second magnetic field intensity at which the number of errors starts to increase is detected, and a difference between the first magnetic field intensity and the second magnetic field intensity is detected. The method for detecting a magnetic field strength according to claim 1, wherein an average value is determined as the influence magnetic field strength. 3. The method according to claim 1, wherein in the first and third steps, a random data pattern recorded on the magneto-optical recording medium is reproduced. 4. A magneto-optical disk device for recording a signal on a magneto-optical recording medium using a laser beam and a magnetic field and reproducing a signal from the magneto-optical recording medium using a laser beam, A magnetic head for applying a magnetic field to the medium; a lowering unit for lowering the magnetic head so as to be in contact with the magneto-optical recording medium; and a magneto-optical device disposed on the opposite side of the magnetic head with the magneto-optical recording medium interposed therebetween. An optical head including an objective lens for converging and irradiating a recording medium with laser light, a first magnet for performing tracking servo of the objective lens, and a second magnet for performing focus servo of the objective lens; A third magnet for canceling a leakage magnetic field generated by at least one of the first and second magnets and convergently incident on the magnetic head. The third magnet emits a magnetic field having an intensity determined by a magnetic field intensity detection method using a DC magnetic field, and the magnetic field intensity detection method irradiates a laser beam to the magneto-optical recording medium, and A first step of reproducing a signal from the magneto-optical recording medium by applying a DC magnetic field in a first direction while changing the intensity at an irradiation point of the laser beam; and a reproduced signal reproduced in the first step. A second step of detecting the number of errors of the above, and a third step of reproducing a signal from the magneto-optical recording medium by applying a DC magnetic field in a second direction opposite to the first direction to the irradiation point. A fourth step of detecting the number of errors in the reproduced signal reproduced in the third step, and the number of errors detected in the second and fourth steps and the intensity of the DC magnetic field. Based on the relationship, and a fifth step of detecting a magnetic field intensity from the first or second magnets in the irradiation point, the magneto-optical disk device. 5. The light according to claim 4, wherein the third magnet is arranged in a radial direction of the magneto-optical recording medium, and has a length longer than a range in which the optical head moves in the radial direction. Magnetic disk drive. 6. The magneto-optical disk device according to claim 4, wherein the third magnet is disposed on the same side as the magnetic head with respect to the magneto-optical recording medium. 7. A laser magnet irradiates a magneto-optical recording medium with a laser beam, a servo magnet of the objective lens detects an intensity of an influence magnetic field exerted on the laser beam irradiation point, and generates a signal using the laser beam and the magnetic field. A magneto-optical disk device that records on a magnetic recording medium and / or reproduces a signal from the magneto-optical recording medium using a laser beam, comprising: a first magnetic head that applies a magnetic field to the magneto-optical recording medium; A lowering means for lowering the first magnetic head so as to be in contact with the magneto-optical recording medium; a laser disposed on the opposite side of the first magnetic head with the magneto-optical recording medium interposed therebetween; An objective lens for condensing and irradiating light, an optical head including the magnet, a second magnetic head for canceling the influence magnetic field, and driving the first magnetic head or the second magnetic head When detecting the intensity of the influencing magnetic field, the control circuit controls the first magnetic head so that the first magnetic head has a direct current magnetic field in a first direction or a direction opposite to the first direction. Controlling the magnetic head drive circuit so as to apply the DC magnetic field in the second direction to the magneto-optical recording medium while changing the intensity of the DC magnetic field, and controlling the error of the reproduction signal detected by the optical head under the application of the DC magnetic field. The magnetic head drive circuit drives the first magnetic head so as to apply the DC magnetic field to the magneto-optical recording medium according to control from the control circuit. The optical head detects a signal from the magneto-optical recording medium, and when reproducing the signal, the control circuit applies a magnetic field having the same intensity as the determined influence magnetic field to the second magnetic head. The magnetic head drive circuit controls the magnetic head drive circuit to generate the magnetic field, and the magnetic head drive circuit drives the second magnetic head to generate a magnetic field having the same intensity as the intensity of the influence magnetic field according to the control of the control circuit. , Magneto-optical disk drive.