JPH11162034A - Magneto-optical head and magneto-optical recording/ reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magneto-optical head capable of speedily and densely recording/reproducing information and being miniaturized and to provide a magneto-optical recording/reproducing device using the head. SOLUTION: A coil 2 of a magnetic head 6 consists of a metallic thin film, and is formed on an upper surface of a transparent body 5 of an opposite L- shaped section. The transparent body 5 is constituted so that a transparent substrate 21 and a support member 51 are integrally molded, and the support member 51 is fixed to an actuator 4 so that the transparent substrate 21 keeps a fixed interval from an objective lens 3. A laser beam outgoing from an optical pickup device 1 is converged on an optical disk 100 surface through the central part of the coil 2 by the object lens 3. The coil 2 on the transparent substrate 21 is arranged so that a center of a magnetic field coincides with the optical axis of the laser beam converged by the objective lens 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magneto-optical head for recording and reproducing information on and from a magneto-optical recording medium, and a magneto-optical recording and reproducing apparatus using the same.

[0002]

2. Description of the Related Art A magneto-optical recording and reproducing apparatus is used for recording and reproducing information on a magneto-optical recording medium such as a magneto-optical disk. FIG. 18 is a schematic diagram showing a schematic configuration of a conventional magneto-optical recording / reproducing apparatus.

[0003] As shown in FIG.
0 is rotationally driven by the spindle motor 31. The optical pickup device 60 and the magnetic head 70 are arranged to face each other with the magneto-optical disk 100 interposed therebetween. Normally, the optical pickup device 60 is the magneto-optical disk 1
The magnetic head 70 is disposed on the signal recording surface side of the magneto-optical disk 100.

The optical pickup device 60 irradiates a laser beam onto the surface of the magneto-optical disk 100 and detects return light (reflected light) from the magneto-optical disk 100.

At the time of recording in the magnetic field modulation system, the surface of the magneto-optical disk 100 is irradiated with a laser beam by the optical pickup device 60 while rotating the magneto-optical disk 100 by the spindle motor 31. As a result, the signal recording layer made of the magnetic material of the magneto-optical disk 100 is heated to the Curie temperature or higher, and the coercive force of the signal recording layer is reduced.
At the same time, an external magnetic field is applied to the irradiation position of the laser beam by flowing a current modulated based on the information to be recorded to the magnetic head 70. Thereby, each position of the signal recording layer of the magneto-optical disk 100 is magnetized in the direction of the external magnetic field.

At the time of reproduction, a laser beam is applied to the surface of the magneto-optical disk 100 by the optical pickup device 60 while rotating the magneto-optical disk 100 by the spindle motor 31 and the return light (reflected light) from the magneto-optical disk 100 is detected. I do. When the laser beam is reflected from the surface of the magnetic material, the plane of polarization rotates in one direction or the opposite direction depending on the direction of magnetization due to the Kerr effect. Therefore, by detecting the rotation direction of the polarization plane based on the return light from the magneto-optical disk 100,
00 can be reproduced.

[0007]

SUMMARY OF THE INVENTION Magneto-optical disk 100
In order to record information at a high density, the optical axis of the laser beam emitted from the optical pickup device 60 must exactly match the center of the magnetic field generated by the magnetic head 70. As a method for accurately reproducing information from the magneto-optical disk 100 recorded at high density, a magnetic domain enlarging and reproducing technique (MAMMOS: Magnetic Amplifying Magnet) is used.
o-Optical System) has been proposed. Also in magnetic domain expansion reproduction, since it is necessary to apply a laser beam and a magnetic field to a portion of the magneto-optical disk 100 to be reproduced, it is necessary to exactly match the optical axis of the laser beam with the center of the magnetic field.

However, in the conventional magneto-optical recording / reproducing apparatus, the optical pickup device 60 and the magnetic head 70
Are provided on the opposite side of the magneto-optical disk 100, so that the optical axis of the laser beam emitted by the optical pickup device 60 and the center of the magnetic field generated by the magnetic head 70 can be accurately matched. Have difficulty. Therefore, it is difficult to perform high-density recording and reproduction with the magneto-optical disk 100.

Further, since the optical pickup device 60 and the magnetic head 70 are located on opposite sides of the magneto-optical disk 100, the size of the magneto-optical recording / reproducing device cannot be reduced.

Further, in order to record information on the magneto-optical disk 100 at high speed and high density, it is necessary to change the magnetic field at high speed by changing the current applied to the magnetic head 70 at high speed. Since it is difficult to change a large current at high speed, it is necessary to bring the magnetic head 70 close to the surface of the magneto-optical disk 100 so that a magnetic field of sufficient strength can be applied to the magneto-optical disk 100 with a small current.

However, since the magnetic head 70 is disposed on the signal recording surface side of the magneto-optical disk 100, the magnetic head 70 comes into contact with the signal recording surface of the magneto-optical disk 100 due to vibration or the like and damages the signal recording surface. May be given.

In order to achieve higher density, it is desirable to perform near light reproduction by bringing the exit of the laser beam from the optical pickup device 60 closer to the signal recording surface of the magneto-optical disk 100.

However, since the optical pickup device 60 is disposed on the substrate side of the magneto-optical disk 100, the exit of the laser beam cannot be brought close to the signal recording surface of the magneto-optical disk 100.

An object of the present invention is to provide a magneto-optical head capable of high-speed, high-density recording and reproduction and miniaturization, and a magneto-optical recording and reproducing apparatus using the same.

[0015]

Means for Solving the Problems and Effects of the Invention (1)
A magneto-optical head according to a first aspect of the present invention is a magneto-optical head for recording and reproducing information on and from a magneto-optical recording medium, comprising an optical system for irradiating a light beam to the magneto-optical recording medium and an optical system. A thin-film coil for applying a magnetic field to the magnetic recording medium,
The optical system and the thin-film coil are arranged on the same side of the magneto-optical recording medium.

In the magneto-optical head according to the present invention, since the optical system and the thin-film coil are arranged on the same side of the magneto-optical recording medium, the optical axis of the light beam irradiated on the magneto-optical recording medium by the optical system can be adjusted. It is easy to match the center of the magnetic field generated by the thin film coil. Therefore, high-density recording and reproduction can be performed. Further, the size of the magneto-optical head can be reduced.

(2) Second invention A magneto-optical head according to a second invention is the magneto-optical head according to the first invention, wherein a light beam applied to the magneto-optical recording medium by the optical system is a thin film coil. The thin-film coil is arranged so as to pass through the center of the above.

In this case, it is easier to make the optical axis of the light beam irradiated on the magneto-optical recording medium by the optical system coincide with the center of the magnetic field generated by the thin-film coil, and to further reduce the size. Can be.

(3) Third Invention A magneto-optical head according to a third aspect of the present invention is the magneto-optical head according to the first or second aspect, wherein the thin-film coil comprises:
It moves with the movement of the light beam by the optical system.

This prevents the optical axis of the light beam irradiated on the magneto-optical recording medium by the optical system when the light beam moves from being shifted from the center of the magnetic field generated by the thin film coil.

(4) Fourth Invention A magneto-optical head according to a fourth invention is a magneto-optical head for recording and reproducing information on and from a magneto-optical recording medium. An optical pickup device for receiving the return light of the optical pickup device, and an objective lens for condensing light emitted from the optical pickup device on a magneto-optical recording medium,
A magnetic head having a coil formed of a conductive thin film and applying a magnetic field to the magneto-optical recording medium from the same side as the optical pickup device.

In the magneto-optical head according to the present invention, since the magnetic head applies a magnetic field to the magneto-optical recording medium from the same side as the optical pickup device, the optical axis of the light beam applied to the magneto-optical recording medium by the optical pickup device And the center of the magnetic field generated by the magnetic head. Therefore, high-density recording and reproduction can be performed.

Further, since the pickup device and the magnetic head are arranged on the same side and the coil of the magnetic head is made of a conductive thin film, the size of the magneto-optical head can be reduced.

(5) Fifth Invention In the magneto-optical head according to the fifth invention, in the configuration of the magneto-optical head according to the fourth invention, the light is irradiated onto the magneto-optical recording medium from the optical pickup device through the objective lens. The magnetic head is arranged so that the light beam passes through the center of the coil.

In this case, it is easier to make the optical axis of the light beam irradiated on the magneto-optical recording medium by the optical pickup device coincide with the center of the magnetic field generated by the magnetic head, and to further reduce the size. be able to.

(6) Sixth invention A magneto-optical head according to a sixth invention is the same as the magneto-optical head according to the fourth or fifth invention, except that the magneto-optical head has an objective lens and a magneto-optical recording medium. The driving member is further provided so as to be relatively movable, and the coil is provided so as to be movable integrally with the driving member.

This prevents the optical axis of the light beam focused on the magneto-optical recording medium by the objective lens from being shifted from the center of the magnetic field generated by the coil when the objective lens is moved by the driving member.

(7) Seventh Invention A magneto-optical head according to a seventh aspect of the present invention is the magneto-optical head according to the sixth aspect, wherein the coil is formed on a transparent substrate, and the transparent substrate is collected by an objective lens. It is disposed between the objective lens and the magneto-optical recording medium such that the optical axis of the light beam to be emitted coincides with the center of the magnetic field generated by the coil, and is fixed to the drive member via a support member. is there.

In this case, the thin film coil can be brought close to the surface of the magneto-optical recording medium in a state where the optical axis of the light beam focused by the objective lens coincides with the center of the magnetic field generated by the coil. As a result, a magnetic field of a sufficient intensity is applied to the magneto-optical recording medium with a small current, so that high-speed and high-density recording and reproduction can be realized by changing the current supplied to the coil at a high speed.

(8) Eighth Invention In the magneto-optical head according to the eighth invention, in the configuration of the magneto-optical head according to the fourth or fifth invention, the objective lens is integrally formed on a transparent substrate, and Is formed on a transparent substrate so as to surround the periphery of the objective lens.

Thus, the optical axis of the light beam focused on the magneto-optical recording medium by the objective lens does not deviate from the center of the magnetic field generated by the coil.

(9) Ninth Invention In a magneto-optical head according to a ninth invention, in the configuration of the magneto-optical head according to the fourth or fifth invention, the coil is formed on a transparent substrate, and the transparent substrate is an objective. It is arranged between the objective lens and the magneto-optical recording medium so that the optical axis of the light beam condensed by the lens coincides with the center of the magnetic field generated by the coil, and is fixed to the optical pickup device via the support member It was done.

In this case, the coil is formed integrally with the optical pickup device and moves together with the magneto-optical recording medium.

(10) Tenth invention A magneto-optical head according to a tenth aspect of the present invention is the magneto-optical head according to any one of the fourth to ninth aspects, wherein the coil has one layer with an insulating film interposed therebetween. Alternatively, it is formed in a concentric or spiral shape in a plurality of layers.

As a result, a thin coil is realized, so that the coil can be brought closer to the surface of the magneto-optical recording medium, and the size can be further reduced.

(11) Eleventh Invention A magneto-optical head according to an eleventh aspect of the present invention is the magneto-optical head according to any one of the fourth to ninth aspects, wherein the coil extends along the moving direction of the objective lens. It generates a magnetic field having a constant strength within a predetermined range.

Thus, even when the objective lens moves, the intensity of the magnetic field at the irradiation position of the light beam focused on the magneto-optical recording medium by the objective lens becomes constant.

(12) Twelfth Invention In the magneto-optical head according to the twelfth invention, in the configuration of the magneto-optical head according to the eleventh invention, the coils are arranged so as to be shifted by a predetermined distance in the moving direction of the objective lens. It is made up of a plurality of elliptical coils. As a result, a magnetic field having a constant strength is obtained in the moving direction of the objective lens.

(13) Thirteenth Invention In the magneto-optical head according to the thirteenth invention, in the configuration of the magneto-optical head according to the fourth or fifth invention, the coil has a configuration in which a coil of the light beam condensed by the objective lens is formed. The converging lens is formed on a converging lens that further narrows the diameter. It is arranged between a medium and fixed to an objective lens via a support member.

In this case, a light beam having a smaller diameter can be applied to the magneto-optical recording medium, and the coil can be brought closer to the surface of the magneto-optical recording medium. Thereby, near light reproduction is realized, and high-speed and high-density recording and reproduction can be performed.

(14) Fourteenth Invention A magneto-optical recording and reproducing apparatus according to a fourteenth invention is a magneto-optical recording and reproducing apparatus for recording and reproducing information on and from a magneto-optical recording medium. A rotation drive mechanism, a magneto-optical head according to any one of the first to thirteenth inventions, a coil drive circuit for driving a coil of the magneto-optical head, and a light source for driving an optical system or an optical pickup device of the magneto-optical head It comprises a drive circuit and a signal processing circuit for processing an output signal from the optical system of the magneto-optical head or the optical pickup device.

In the magneto-optical recording / reproducing apparatus according to the present invention, since the magneto-optical head according to any one of the first to thirteenth aspects is used, high-speed and high-density recording / reproducing can be performed and the size is small. Is possible.

[0043]

FIG. 1 is a schematic diagram showing a configuration of a magneto-optical head according to a first embodiment of the present invention.

In FIG. 1, the magneto-optical disk 100 is
It is rotationally driven by a spindle motor 31. Hereinafter, the focus direction (the direction perpendicular to the surface of the magneto-optical disk 100) is represented by F, and the tracking direction (the magneto-optical disk 1
00 in the radial direction) is represented by T. The direction perpendicular to the plane of FIG. 1 is the track direction of the magneto-optical disk 100.

The magneto-optical head 30 includes an optical pickup device 1, a coil 2, and an objective lens 3. The actuator 4 is provided movably in the tracking direction T while holding the objective lens 3.

The coil 2 is made of a metal thin film as described later, and is formed on the upper surface of a transparent body 5 having an inverted L-shaped cross section. The transparent body 5 has a transparent substrate 21 and a supporting member 51 integrally formed, and the supporting member 51 is fixed to the actuator 4 so that the transparent substrate 21 is kept at a constant distance from the objective lens 3. Thereby, the coil 2 is moved by the actuator 4 together with the objective lens 3 in the tracking direction T.
Go to The coil 2 and the transparent body 5 constitute a magnetic head 6.

The laser beam emitted from the semiconductor laser element 11 of the optical pickup device 1 passes through the collimator lens 13, is reflected in the focusing direction F by the rising mirror 18, and is passed through the center of the coil 2 by the objective lens 3 to the optical disk. The light is focused on the surface of 100. The detailed configuration of the optical pickup device 1 will be described later.

FIG. 2 is a diagram showing the positional relationship among the magnetic head 6, the objective lens 3, and the magneto-optical disk 100 in the magneto-optical head 30 of FIG.

As shown in FIG. 2, the laser beam passes through the transparent substrate 21 by the objective lens 3 and is focused on the signal recording surface 150 of the magneto-optical disk 100. Transparent substrate 21
The upper coil 2 is arranged such that the center of the magnetic field coincides with the optical axis of the laser beam focused by the objective lens 3. The numerical aperture of the objective lens 3 is, for example, 0.45 to 0.5.
65.

Since the coil 2 is formed of a thin metal film, the distance L between the magnetic head 6 and the magneto-optical disk 100 can be set within a range of 1 to 100 μm. The thickness of the magneto-optical disk 100 is 0.1 to 0.6 mm
It is. Thereby, the magnetic head 6 and the magneto-optical disk 1
The distance between the signal recording surface 150 and the signal recording surface 150 is 0.1 to 0.7.
mm. In this case, the inside diameter of the coil 2 is in the range of 1 to 3 mm.

FIG. 3 is an enlarged perspective view of the magnetic head 6, FIG. 4 is a schematic sectional view of the coil 2 in the magnetic head 6 of FIG.
FIG. 5 is a plan view of the coil 2 in the magnetic head 6 of FIG.

As shown in FIG. 3, the coil 2 is composed of a plurality of concentrically formed annular metal thin films 22. No metal thin film 22 is provided in the optical path of the laser beam focused by the objective lens 3. Therefore, the laser beam is not scattered by the coil 2. Note that the metal thin film 22 may be arranged in a spiral shape.

As shown in FIG. 4, a plurality of annular metal thin films 22 are laminated on a transparent substrate 21 with an insulating film 23 interposed therebetween. The transparent substrate 21 is made of, for example, polycarbonate. The metal thin film 22 is made of Cu, Au, or the like, and is patterned by a photolithography technique.
The metal thin film 22 has a thickness of 2 μm, a width of 40 μm, and a pitch of 50 μm.

The insulating film 23 is made of SiO ₂ , organic SOG (spin-on-glass) or the like. The film thickness of the insulating film 23 is set to 0.
2 to 5 μm. The number of turns of the metal thin film 22 per layer is 50 turns, and for example, ten layers of the metal thin film 22 are formed. In that case, the film thickness of the entire coil is 13 to 70 μm
It can be made as thin as possible.

As shown in FIG. 5, both ends of the metal thin film 22 of each layer are connected to metal wiring layers 24 and 25, respectively. As a result, current is supplied from the metal wiring layers 24 and 25 to the plurality of metal thin films 22 in parallel.

FIG. 6 shows a coil 2 using a thin insulating film.
FIG. 3 is a schematic sectional view of FIG. As shown in FIG.
A plurality of ring-shaped metal thin films 22a having a thickness of 2 μm are formed concentrically on 1 and are covered with a thin insulating film 23a having a thickness of 0.2 μm. Further, a plurality of 2 μm-thick annular metal thin films 22b are similarly formed on the insulating film 23a between the annular metal thin films 22a, and are covered with the insulating film 23b.

As described above, the thickness of the insulating films 23a and 23b is made smaller than the thickness of the metal thin films 22a and 22b, and the metal thin film 22b of each layer is positioned between the lower metal thin films 22a. The surface of the coil 2 can be kept flat, and the entire coil 2 can be made thinner.

FIG. 7 is a schematic diagram showing the structure of the optical pickup device of the magneto-optical head 30 of FIG. 7 does not show the rising mirror 18 shown in FIG.

As shown in FIG. 7, the optical pickup device 1
Includes a semiconductor laser element 11, a diffraction grating 12, a collimator lens 13, a half mirror 14, a Wollaston prism 15, a condenser lens 16, and a photodetector 17.

The semiconductor laser device 11 has a wavelength of 63, for example.
A laser beam of 5 to 680 nm is emitted. The laser beam emitted from the semiconductor laser element 11 is
The light is diffracted into the 0th, + 1st, and -1st order by 2 and is collimated by the collimator lens 13. The parallel light is
The light passes through the half mirror 14 and is condensed on the signal recording surface 105 of the magneto-optical disk 100 by the objective lens 3.

The return light (reflected light) from the magneto-optical disk 100 is reflected by the half mirror 14 through the objective lens 3 and enters the Wollaston prism 15. The return light that has entered the Wollaston prism 15 is separated into light of a P-polarized (Parallel Polarization) component and light of an S-polarized (Sagittal Polarization) component whose polarization planes are orthogonal to each other, and light containing both components. As a result, three light spots are condensed on the light receiving surface of the photodetector 17.

Of the three light spots on the light receiving surface of the photodetector 17, two light spots on both sides contain a P-polarized component and an S-polarized component, respectively, and the central light spot contains both components. A reproduction signal is generated from the difference between the light spots on both sides, and a tracking error signal and a focus error signal are generated from the central light spot.

In the magneto-optical head 30 of this embodiment,
Since the coil 2 is formed of a metal thin film, the thickness of the magnetic head 6 is reduced. Thus, the magnetic head 6 can be arranged at a position close to the magneto-optical disk 100. Therefore, the required magnetic field strength (150 to 200 Oe) can be obtained without passing a large current through the coil 2. As a result, the magnetic field intensity can be modulated at a high frequency, and information can be recorded on the magneto-optical disk 100 at high speed and high density.

Further, since the coil 2 is formed integrally with the actuator 4 of the objective lens 3, the coil 2 moves together with the objective lens 3. Therefore, the optical axis of the laser beam focused by the objective lens 3 does not deviate from the center of the magnetic field generated by the coil 2 during tracking.

Further, since the optical pickup device 1 and the magnetic head 6 are provided on the same side of the magneto-optical disk 100, the size of the magneto-optical head 30 is reduced.

FIG. 8 is a schematic diagram showing the configuration of a magneto-optical head according to the second embodiment of the present invention. FIG. 9 shows FIG.
FIG. 4 is an enlarged perspective view of an objective lens and a magnetic head in the magneto-optical head of FIG.

As shown in FIG. 8, in the magneto-optical head 30 of this embodiment, the transparent substrate 21a of the magnetic head 6a and the objective lens 3a are integrally formed, and the transparent substrate 21a
Are held by the actuator 4. Objective lens 3a
The coil 2a is provided on the transparent substrate 21a around the.

In the example of FIG. 9, a plurality of annular metal thin films 22 are formed concentrically on a transparent substrate 21a so as to surround the periphery of the objective lens 3a. The metal thin film 22
May be arranged spirally. The configuration of another part of the magneto-optical head 30 of the present embodiment is similar to that of the magneto-optical
The configuration is the same as that described above.

When the magnetic domain expansion reproduction technique is used in the magneto-optical head 30 of the first and second embodiments, information can be read from the magneto-optical disk 100 recorded at high density with high accuracy. FIG. 10 is a diagram for explaining magnetic domain expansion reproduction.

As shown in FIG. 10A, the magneto-optical disk 100 for magnetic domain expansion reproduction has at least the reproduction layer 200.
And a recording layer 300. Magnetic domains are recorded upward or downward in the recording layer 300. The reproduction layer 2
The magnetic domains of 00 are all upward. In this state, the reproducing layer 200 is irradiated with a laser beam, and the magnetic domain of the recording layer 300 to be reproduced is heated to a predetermined temperature.

Next, as shown in FIG. 10B, the magnetic domains of the recording layer 300 heated to a predetermined temperature or higher are transferred to the reproducing layer 200 by the exchange coupling force. Then, a downward external magnetic field B1 is applied. When the direction of the transferred magnetic domain is the same as the direction of the external magnetic field B1, the area of the transferred magnetic domain is enlarged as shown by the oblique lines. Information is reproduced at the timing when the magnetic domain is expanded as described above.

Thereafter, as shown in FIG. 10C, an upward external magnetic field B2 is applied. Since the direction of the magnetic domain transferred to the reproducing layer 200 is opposite to the direction of the external magnetic field B2,
The enlarged magnetic domain of the reproducing layer 200 disappears, and FIG.
Return to the state.

The information recorded on the recording layer 300 is sequentially reproduced by repeating the steps from FIG. 10 (a) to FIG. 10 (c).

In this manner, information recorded on the magneto-optical disk 100 at high density can be reproduced with high accuracy.

When the direction of the magnetic domain to be transferred in the step of FIG. 10B is opposite to the direction of the external magnetic field B1,
No magnetic domain reversal occurs in the reproducing layer 200, and
Since the magnetic domain of 0 is already in the same direction as the magnetic domain to be transferred, the same effect as when the magnetic domain is enlarged can be obtained.

FIG. 11 is a schematic diagram showing the configuration of a magneto-optical head according to the third embodiment of the present invention.

In the magneto-optical head 30 of this embodiment,
Like the magneto-optical head 30 of the first embodiment, the coil 2b
Is formed of a metal thin film and is formed on the upper surface of a transparent body 5b having an inverted L-shaped cross section. The transparent body 5b is formed by integrally forming the transparent substrate 21b and the support member 51b.
b is fixed to the optical pickup device 1. Coil 2
b and the transparent body 5b constitute the magnetic head 6b. The configuration of the other part of the magneto-optical head 30 of this embodiment is the same as the configuration of the magneto-optical head 30 of FIG.

In the magneto-optical head 30 of this embodiment,
Since the magnetic head 6b is formed integrally with the optical pickup device 1, when the objective lens 3 moves in the tracking direction T during tracking, it is generated by the optical axis of the laser beam focused by the objective lens 3 and the coil 2b. The center of the applied magnetic field. Therefore, it is necessary for the coil 2b to generate a magnetic field having a constant strength within the moving range of the objective lens 3.

FIG. 12 is an enlarged perspective view of the magnetic head 6b of the magneto-optical head 30 of FIG. 11, and FIG. 13 is a plan view of the coil 2b of the magnetic head 6b of FIG.

As shown in FIGS. 12 and 13, the coil 2b includes a plurality of elliptical metal thin films 22A, 22B, 2B.
2C and 22D. Each of the elliptical metal thin films 22A, 22B, 22C, and 22D is disposed so that the major axis is parallel to the tracking direction T, and their centers 27A, 27B, 27C, and 27D are spaced at a constant distance along the tracking direction T. It is shifted by one. Thereby,
The coil 2b can generate a magnetic field having a constant strength within a certain range in the tracking direction T.

By using the coil 2b of FIGS. 12 and 13 for the magneto-optical head 30 of FIG. 11, even if the objective lens 3 moves in the tracking direction T relative to the coil 2b during tracking, 10
The intensity of the magnetic field applied to the irradiation position of the laser beam above zero does not change.

The coil 2b shown in FIGS. 12 and 13 may be applied to the magnetic heads 6 and 6a of the magneto-optical head 30 of the first and second embodiments.

In particular, the coil 2b shown in FIGS.
Is effective for magnetic domain expansion reproduction in which an external magnetic field is applied during reproduction.

FIG. 14 is a schematic diagram showing a partial configuration of a magneto-optical head according to the fourth embodiment of the present invention. FIG. 14 shows only the magnetic head 6c and the objective lens 3.

As shown in FIG. 14, a solid immersion lens 21c is placed at the upper end opening of the cylindrical support member 5c.
Is attached, and the objective lens 3 is attached to the lower end opening of the support member 5c. A coil 2c made of a metal thin film is formed on the upper surface of the solid immersion lens 21c. The configuration of other parts of the magneto-optical head of the present embodiment is the same as the configuration of the magneto-optical head 30 of FIG.

In the magneto-optical head of this embodiment, since the laser beam condensed by the objective lens 3 is further converged by the solid immersion lens 21c, the magnetic head 6c is moved closer to the signal recording surface of the magneto-optical disk. High-resolution proximity light reproduction can be performed with the laser beam narrowed.

In such proximity light reproduction, a laser beam is irradiated from the signal recording surface side of the magneto-optical disk. Therefore, the magneto-optical head of this embodiment is arranged on the signal recording surface side of the magneto-optical disk.

FIG. 15 is a schematic sectional view showing the structure of a magneto-optical disk suitable for reproduction by the magneto-optical heads of the first, second and third embodiments.

The magneto-optical disk 100 shown in FIG.
Here, on a substrate 101 made of polycarbonate,
A recording / reproducing layer 102 made of TbFeCo, a heat dissipation layer 103 made of Al, and a protective layer 104 made of SiN are sequentially stacked. This magneto-optical disk 100 has one magnetic layer (recording / reproducing layer 102).

The magneto-optical disk 100 shown in FIG.
In the above, a reproduction layer 102a made of GdFeCo and a TbFeC
recording layer 102b made of o, heat dissipation layer 103 made of Al
And a protective layer 104 made of SiN. This magneto-optical disk 100 has two magnetic layers (a reproducing layer 102a and a recording layer 102b).

The magneto-optical disk 100 shown in FIG.
In the structure of the magneto-optical disk 100 shown in FIG. 15B, a nonmagnetic layer 105 made of SiN is provided between the reproducing layer 102a and the recording layer 102b. This magneto-optical disk 100 is suitable for magnetic domain expansion reproduction.

FIG. 16 is a schematic sectional view showing the structure of a magneto-optical disk suitable for proximity light reproduction by the magneto-optical head of the fourth embodiment.

The magneto-optical disk 100 shown in FIG.
, A heat dissipation layer 103 made of Al, a recording / reproducing layer 102 made of TbFeCo, and a protective layer 104 made of SiN are formed on a substrate 101 made of polycarbonate.
Are sequentially stacked. This magneto-optical disk 100
It has one magnetic layer (recording / reproducing layer 102).

The magneto-optical disk 100 shown in FIG.
, A heat radiation layer 103 made of Al, a recording layer 102b made of TbFeCo, and a reproduction layer 102a made of GdFeCo are formed on a substrate 101 made of polycarbonate.
And a protective layer 104 made of SiN. The magneto-optical disk 100 has two magnetic layers (a recording layer 102b and a reproducing layer 102a).

The magneto-optical disk 100 shown in FIG.
In the structure of the magneto-optical disk 100 shown in FIG. 16B, a nonmagnetic layer 105 made of SiN is provided between the recording layer 102b and the reproducing layer 102a. This magneto-optical disk 100 is suitable for magnetic domain expansion reproduction.

According to the magneto-optical head 30 of the first, second and third embodiments, the substrate 101 of the magneto-optical disk 100
15, the recording / reproducing layer 102 or the reproducing layer 102a is provided on the substrate 101 side, and the heat radiation layer 103 is provided on the protective layer 104 side in the magneto-optical disk 100 of FIG. . On the other hand, according to the magneto-optical head of the fourth embodiment, since the laser beam is irradiated from the opposite side of the magneto-optical disk 100 from the substrate 101,
In the magneto-optical disk 100 of FIG. 16, the heat radiation layer 103 is provided on the substrate 101 side, and the recording / reproducing layer 102 or the reproducing layer 102a is provided on the protective layer 104 side.

FIG. 17 is a block diagram showing the configuration of a magneto-optical recording / reproducing apparatus using the magneto-optical head 30 of the above embodiment.

In FIG. 17, a spindle motor 31 drives the magneto-optical disk 100 to rotate. Servo circuit 32
Controls the spindle motor 31 and the magneto-optical head 30. The magnetic head drive circuit 33 includes the magneto-optical head 30.
Drive the magnetic head inside. The laser drive circuit 34 drives a semiconductor laser element in the magneto-optical head 30. The reproduced signal output from the photodetector in the magneto-optical head 30 is:
The reproduction signal is supplied to the reproduction signal amplification circuit 35.

At the time of the recording operation, a recording signal is supplied to the data encoding circuit 36. Data encoding circuit 3
Reference numeral 6 denotes a signal modulation by compressing a recording signal by a data compression technique such as an MPEG (Motion Picture Experts Group) method and adding management information such as a reproduction time, an elapsed time, an address and an error correction code to the compressed recording signal. Circuit 3
Give 7

The signal modulation circuit 37 modulates the recording signal to which the management information has been added into, for example, 1-7 RLL data, and supplies the data to the timing pulse generation circuit 38. The timing pulse generation circuit 38 converts 1-7 RLL data into a pulse signal having a predetermined duty ratio, sets a predetermined phase difference, and supplies the pulse signal to the magnetic head drive circuit 33 and the laser drive circuit 34. .

The laser drive circuit 34 turns on and off the semiconductor laser element in the magneto-optical head 30 in response to the pulse signal given from the timing pulse generation circuit 38. As a result, the magneto-optical disk 100 is irradiated with the laser beam pulsed by the magneto-optical head 30.

The magnetic head driving circuit 33 drives the magnetic head in the magneto-optical head 30 in response to a pulse signal given from the timing pulse generating circuit 38. Thus, information based on the recording signal is recorded on the magneto-optical disk 100.

In the above description, the magneto-optical head 30
The information recording by irradiating the pulse light for turning on and off the semiconductor laser element described above has been described. However, when recording the information by irradiating the magneto-optical disk 100 with continuous light, the timing pulse generating circuit 38 is not provided, Modulation circuit 3
The data modulated by 7 is directly applied to the magnetic head drive circuit 33 only.

At the time of the reproducing operation, a laser beam having a wavelength of 635 to 680 nm is emitted from the semiconductor laser element in the magneto-optical head 30, and the laser beam is
The signal is irradiated onto the signal recording surface of the magneto-optical disk 100 through an objective lens having a numerical aperture of 0.45 to 0.65.

The return light reflected on the signal recording surface of the magneto-optical disk 100 is detected by a photodetector in the magneto-optical head 30. As a result, a reproduction signal based on the information recorded on the magneto-optical disk 100 is output from the magneto-optical head 30 and supplied to the reproduction signal amplifier circuit 35. After amplifying the reproduced signal, the reproduced signal amplifying circuit 35 supplies the amplified reproduced signal to the servo circuit 32, the waveform equalizing circuit 39, and the clock generating circuit 44.

The servo circuit 32 includes a reproduction signal amplification circuit 35
The spindle motor 31 and the magneto-optical head 30 are controlled in response to the reproduced signal amplified by the above.

The waveform equalization circuit 39 performs a waveform equalization process on the reproduced signal. The clock generation circuit 44 generates a clock signal used for signal reproduction based on the reproduction signal. The waveform equalization circuit 39 sends the reproduced signal whose waveform has been equalized to the first decoder 40 and the second decoder 41 in order.

First decoder 40 and second decoder 41
Demodulates the reproduced signal by the 1-7 RLL system in synchronization with the clock signal generated by the clock generating circuit 44 and supplies the demodulated reproduced signal to the format decoder circuit 42. The format decoder circuit 42 extracts only the data portion of the demodulated reproduction signal, and
Give to 3. The data decoder circuit 43 expands the data portion provided from the format decoder circuit 42 and outputs a reproduced signal.

When performing the magnetic domain expansion reproduction, the clock signal generated by the clock generation circuit 44 is also supplied to the magnetic head drive circuit 33. The magnetic head driving circuit 33 synchronizes the clock signal with the magneto-optical head 3.
Drive the coil in 0. Thereby, the magneto-optical head 3
0 causes an alternating magnetic field to be applied to the magneto-optical disk 100.

In this embodiment, the spindle motor 31 corresponds to a rotary drive mechanism, the magnetic head drive circuit 33 corresponds to a coil drive circuit, and the laser drive circuit 34 corresponds to a light source drive circuit. Further, the reproduction signal amplification circuit 35, the waveform equalization circuit 39, the first decoder 40, the second decoder 41, the format decoder circuit 42, the data decoder circuit 43, and the clock generation circuit 44 constitute a signal processing circuit.

In the magneto-optical recording / reproducing apparatus shown in FIG.
Since the magneto-optical head 30 of the above embodiment is used,
High-speed and high-density recording and reproduction can be performed, and the size can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a magneto-optical head according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a positional relationship among a magnetic head, an objective lens, and a magneto-optical disk in the magneto-optical head of FIG.

FIG. 3 is an enlarged perspective view of a magnetic head in the magneto-optical head of FIG. 1;

FIG. 4 is a schematic sectional view of a coil in the magnetic head of FIG. 3;

FIG. 5 is a plan view of a coil in the magnetic head of FIG. 3;

FIG. 6 is a schematic sectional view of a coil when a thin insulating film is used.

FIG. 7 is a schematic diagram showing a configuration of an optical pickup device in the magneto-optical head of FIG. 1;

FIG. 8 is a schematic diagram showing a configuration of a magneto-optical head according to a second embodiment of the present invention.

FIG. 9 is an enlarged perspective view of an objective lens and a magnetic head in the magneto-optical head of FIG.

FIG. 10 is a diagram for explaining magnetic domain expansion reproduction.

FIG. 11 is a schematic diagram showing a configuration of a magneto-optical head according to a third embodiment of the present invention.

12 is an enlarged perspective view of a magnetic head in the magneto-optical head of FIG.

FIG. 13 is a plan view of a coil in the magnetic head of FIG.

FIG. 14 is a schematic diagram showing a configuration of a magnetic head of a magneto-optical head according to a fourth embodiment of the present invention.

FIG. 15 is a schematic sectional view showing the structure of a magneto-optical disk suitable for reproduction by the magneto-optical head of the first, second and third embodiments.

FIG. 16 is a schematic sectional view showing the structure of a magneto-optical disk suitable for reproducing the magneto-optical disk of the fourth embodiment.

FIG. 17 is a block diagram showing a configuration of a magneto-optical recording / reproducing apparatus using the magneto-optical head according to the first to fourth embodiments.

FIG. 18 is a schematic diagram showing an arrangement of a magnetic head and an optical pickup device in a conventional magneto-optical recording / reproducing apparatus.

[Explanation of symbols]

Reference Signs List 1 optical pickup device 2, 2a, 2b, 2c coil 3 objective lens 4 actuator 5, 5b, transparent body 51, 51b, 5c support member 6, 6a, 6b, 6c magnetic head 11 semiconductor laser element 21, 21a, 21b transparent substrate 21c Solid immersion lens 22, 22a, 22b, 22A, 22B, 22C, 22
D Metal thin film 30 Magneto-optical head 31 Spindle motor 32 Servo circuit 33 Magnetic head drive circuit 34 Laser drive circuit 35 Reproduction signal amplifier circuit 100 Magneto-optical disk

Claims (14)

[Claims] 1. A magneto-optical head for recording and reproducing information on and from a magneto-optical recording medium, wherein the optical system irradiates a light beam to the magneto-optical recording medium and a magnetic field is applied to the magneto-optical recording medium. Wherein the optical system and the thin film coil are disposed on the same side of the magneto-optical recording medium. 2. The magneto-optical device according to claim 1, wherein the thin-film coil is arranged so that a light beam applied to the magneto-optical recording medium by the optical system passes through a center portion of the thin-film coil. head. 3. The magneto-optical head according to claim 1, wherein the thin-film coil moves with movement of the light beam by the optical system. 4. A magneto-optical head for recording and reproducing information on and from a magneto-optical recording medium, wherein the optical pickup device emits light and receives return light from the magneto-optical recording medium; An objective lens for condensing light emitted from the device on the magneto-optical recording medium, and a coil formed of a conductive thin film, and applying a magnetic field to the magneto-optical recording medium from the same side as the optical pickup device A magneto-optical head comprising a magnetic head. 5. The magnetic head is arranged so that a light beam emitted from the optical pickup device onto the magneto-optical recording medium through the objective lens passes through a center of the coil. 5. The magneto-optical head according to 4. 6. A driving member which holds the objective lens and is movably provided relative to the magneto-optical recording medium, wherein the coil is movably provided integrally with the driving member. 5. The method according to claim 4, wherein
Or the magneto-optical head according to 5. 7. The coil is formed on a transparent substrate, and the transparent substrate is provided on the object such that an optical axis of a light beam focused by the objective lens coincides with a center of a magnetic field generated by the coil. 7. The magneto-optical head according to claim 6, wherein the magneto-optical head is disposed between a lens and the magneto-optical recording medium, and is fixed to the driving member via a supporting member. 8. The light according to claim 4, wherein the objective lens is formed integrally with a transparent substrate, and the coil is formed on the transparent substrate so as to surround a periphery of the objective lens. Magnetic head. 9. The coil is formed on a transparent substrate, and the transparent substrate is provided on the object such that an optical axis of a light beam focused by the objective lens coincides with a center of a magnetic field generated by the coil. 6. The optical pickup device according to claim 4, wherein the optical pickup device is disposed between a lens and the magneto-optical recording medium and is fixed to the optical pickup device via a support member.
The magneto-optical head as described in the above. 10. The magneto-optical head according to claim 4, wherein said coil is formed in one or more layers in a concentric or spiral manner with an insulating film interposed therebetween. 11. The magneto-optical head according to claim 4, wherein the coil generates a magnetic field having a constant intensity within a predetermined range along a moving direction of the objective lens. 12. The magneto-optical head according to claim 11, wherein the coil comprises a plurality of elliptical coils which are arranged at predetermined distances in the moving direction of the objective lens. 13. The coil is formed on a condenser lens that further narrows the diameter of the light beam focused by the objective lens, and the condenser lens is configured to light the light beam focused by the objective lens. It is arranged between the objective lens and the magneto-optical recording medium such that an axis coincides with the center of a magnetic field generated by the coil, and is fixed to the objective lens via a support member. The magneto-optical head according to claim 4. 14. A magneto-optical recording / reproducing apparatus for recording and reproducing information on / from a magneto-optical recording medium, wherein: a rotation drive mechanism for rotating the magneto-optical recording medium; A magneto-optical head, a coil drive circuit that drives the coil of the magneto-optical head, a light source drive circuit that drives the optical system of the magneto-optical head or the optical pickup device, or the optical system of the magneto-optical head And a signal processing circuit for processing an output signal from the optical pickup device.