JP2000113499A - Optical head, and device provided with it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable performing high speed access and high speed data transfer and to miniaturize and lighten a device. SOLUTION: A light source 1, detectors 3-5, reflectors 10a, 10b, a magnetic coil, and a drive circuit 19 are formed monolithically on a surface of a substrate 2. A diffraction lattice is formed on the reflector 10b, reflected light can be allotted to detectors 3-5. As a light path to each detectors from the reflector 10b is arranged in the direction along the substrate 2, the thickness of an optical head can be thinned. The substrate 2 can be processed to a slider 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flying optical head suitable for high-density recording, and more particularly, to a light source,
The present invention relates to an ultra-small flying optical head and a magneto-optical head integrally provided with a detector and an optical system, and an apparatus for recording or reproducing information by using an optical head or a magneto-optical head.

[0002]

2. Description of the Related Art The recording density of an optical disk is limited by the spot diameter of a light source. The spot diameter of the light source is represented by λ / NA, for example, where the numerical aperture of the objective lens used is NA (generally about 0.5) and the wavelength is λ. Wavelength 680 nm,
When NA = 0.55, the spot diameter is about 1.2 μm. Therefore, it is necessary to reduce the light spot diameter in order to improve the recording density. In order to reduce the diameter of the light spot, it is sufficient to increase the NA of the objective lens or shorten the wavelength according to the above equation, and various approaches have been attempted. When an objective lens having a high NA is used, it is necessary to support the objective lens so as to be considerably close to the optical recording medium because the focal length is further reduced. For this reason, it has been proposed to use a flying head as used in a magnetic disk for a magneto-optical recording medium.

[0003]

However, in the case of an optical head for a magneto-optical recording medium, it is necessary to provide a large lens or mirror on the flying head and introduce light to the disk. However, there is a problem that it takes time for the flying head to access a predetermined recording or reproducing area. In addition, if the flying head is arranged on several disks such as magnetic disks to perform independent recording and reproduction, there is a disadvantage that the volume of the apparatus is increased due to the large flying head.

For example, in JP-A-6-251410,
A semiconductor laser and a photodetector are formed on a substrate via a buffer layer, an opening is formed below a laser light emitting surface and a light receiving surface, and the opening is filled with a first glass layer. An optical head is disclosed in which a grating is formed on the lower surface of a first glass layer, a second glass layer is formed below the first glass layer, and a grating lens having a diameter of 1 mm or less is formed on the lower surface of the second glass layer. This optical head is characterized in that it can be manufactured integrally by using a semiconductor process such as a photomask exposure process, and that a surface emitting laser and a photodiode can be manufactured simultaneously. Also,
In this optical head, since the grating is used, it is possible to branch the reflected light from the recording medium while making the incident light to the recording medium vertical, and to reduce the influence of the reflected light returning to the laser light source. We have reduced.

However, in Japanese Patent Application Laid-Open No. 6-251410, since a grating is used, the thickness of the first glass layer must be reduced in order to ensure that the diffracted light from the grating can be detected by a photodetector. That is,
A predetermined distance from the photodetector to the grating must be ensured, and there is a problem that the volume of the device increases.

Further, in a conventional flying optical head which flies above a magneto-optical recording medium to perform recording and reproduction, a large magnetic field is applied with good followability to an information recording medium irradiated with recording or reproduction light. Not enough. In the future, in order to cope with the ever-increasing density of magneto-optical recording media, a magneto-optical or magnetic head capable of applying a large magnetic field at a sufficiently high speed is demanded.

Accordingly, the present invention has been made to solve the problems of the prior art, and an object of the present invention is to further reduce the size and weight of the device, thereby increasing the access speed to an information recording medium. It is an object of the present invention to provide an optical head and an apparatus including the optical head and capable of recording or reproducing information on an information recording medium.

It is another object of the present invention to provide a floating optical head which includes a laser light source and a detector and is easy to manufacture, and an apparatus including the same.

It is a further object of the present invention to provide an optical head having a magnetic field applying device capable of applying a large magnetic field at a high speed to a magneto-optical recording medium, and an apparatus including the same.

[0010]

According to a first aspect of the present invention, there is provided an optical head for use in an apparatus for recording or reproducing information by irradiating an information recording medium with light. A laser light source for irradiating laser light; a detector for detecting laser light reflected from the information recording medium; and a light guide unit for guiding the laser light reflected from the information recording medium to the detector. The laser light source;
An optical head is provided in which a detector and a light guide are formed integrally (monolithically) on a common substrate.

According to the optical head of the present invention, a laser light source,
Since the detector and the light guide are monolithically formed on a common substrate, a small and lightweight head is realized. Since this head can form all of those elements on a substrate by a semiconductor process, it can be manufactured easily and accurately while having a dense structure. In this head, since the light guide section is formed on a common substrate with the detector, an optical path of the laser light from the light guide section to the detector is formed. Therefore, the optical path length required for tracking and focus servo can be secured in the substrate plane, and the thickness of the optical head can be extremely reduced. Therefore, when the optical head is accommodated in the slider, the slider itself can be made thinner.

[0012] The optical head of the present invention may further include an objective lens for converging laser light from a laser light source on an information recording medium, and a magnetic coil and a yoke coated on the objective lens. Thus, the optical head functions as a magneto-optical head, and is suitable for recording and reproducing on a magneto-optical recording medium. Since this magneto-optical head can be accessed from only one surface of the magneto-optical recording medium when recording and reproducing information, double-sided recording on the magneto-optical recording medium can be realized.

[0013] The light guide section may include a first reflecting mirror and / or a prism for directing the laser beam reflected from the information recording medium to the photodetector. Further, the photodetector has a plurality of detectors, and the first reflector has a diffraction grating on the surface of the first reflector, which divides the laser beam into the respective detectors. Light diffracted by the diffraction grating (for example, 0th order, ± 1st order light)
Goes to each detector. The optical path from the diffraction grating to the detector is in the in-plane direction of the substrate.
Unlike the optical head of No. 51410, the optical path does not increase the thickness of the head.

The light guide may further include a second reflecting mirror for directing a laser beam from the laser light source to the information recording medium. The first and second reflecting mirrors can be integrally formed in a triangular prism shape, so that the optical system can be further simplified.

The light guide section may include a prism for directing the laser beam reflected from the information recording medium to the photodetector instead of or in addition to the diffraction grating. Since the prism is also formed on the substrate, the optical path in the prism is also in the plane of the substrate, contributing to the thinning of the head.

Further, a microactuator for adjusting the course of the laser beam irradiated on the information recording medium may be provided. The laser spot irradiated on the information recording medium by the microactuator can be moved up, down, left, and right, thereby performing autofocus and tracking servo. Further, a drive circuit for driving the magnetic coil may be integrally provided on the substrate. Thus, all functions necessary for the operation of the optical head can be integrally mounted on the substrate.

According to a second aspect of the present invention, there is provided an apparatus for recording or reproducing information on an information recording medium, comprising the optical head according to the first aspect. This device is
Since the optical head is small, light, and thin, it has excellent responsiveness and can operate at high speed. Therefore, it is suitable for recording or reproduction of an information recording medium on which high-density recording is performed, in particular, a magneto-optical recording medium.

According to a third aspect of the present invention, there is provided an optical head for use in an apparatus for recording or reproducing information by irradiating an information recording medium with light, for irradiating the information recording medium with a laser beam. A laser light source; a detector for detecting a laser beam reflected from the information recording medium; a light guide unit for guiding the laser beam reflected from the information recording medium to the detector; A slider having a concave portion formed on a side facing the information recording medium of the slider; and a slider on the bottom of the concave portion of the slider.
An optical head is provided in which the laser light source, the detector and the light guide are integrally formed.

In the flying optical head of this embodiment, since the slider is processed from the semiconductor substrate, the laser light source, the detector and the light guide can be formed directly on the bottom surface of the concave portion of the slider. Therefore, it is possible to provide a floating optical head which is extremely easy to manufacture and precise. Sapphire is preferred as the slider material.

The optical head may include an objective lens for condensing laser light from a laser light source on an information recording medium, and a lens support for supporting the lens on the slider recess. The objective lens and the lens support can be integrally formed by plastic injection molding or the like. The objective lens may include a magnetic coil and a yoke coated thereon. With this configuration, it is possible to apply a magnetic field having a high magnetic flux density to a location very close to the light irradiation unit of the information recording medium, and it is possible to integrate the light irradiation unit and the magnetic field application unit.
As a result, the size of the magneto-optical head can be reduced.

On the side of the slider facing the information recording medium, a kind of layer selected from silicone, alumina, and diamond-like carbon can be formed to give the slider mechanical strength.

According to a fourth aspect of the present invention, there is provided an optical head according to the third aspect, and an arm for supporting the optical head and moving the optical head with respect to the information recording medium for recording or reproducing information. An apparatus is provided. This optical device also has excellent responsiveness and can operate at high speed because the optical head is small, lightweight, and thin. Therefore, it is suitable for recording or reproduction of an information recording medium on which high-density recording is performed, in particular, a magneto-optical recording medium.

According to a fifth aspect of the present invention, there is provided a magneto-optical head used for an apparatus for recording or reproducing information by irradiating an information recording medium with light, comprising: a slider floating above the information recording medium; A laser light source provided on the slider for irradiating the information recording medium with laser light; a detector provided on the slider for detecting laser light reflected from the information recording medium; An objective lens for focusing the laser light from the laser light source on the information recording medium; a magnetic coil provided on the objective lens; and a magnetic material coated on the objective lens. A magneto-optical head is provided.

In the magneto-optical head of this embodiment, since the magnetic coil and the yoke made of a magnetic material are provided on the objective lens,
A magnetic field having a high magnetic flux density can be efficiently applied to the light irradiation portion of the information recording medium. The coating of the yoke and the magnetic coil can be implemented in various ways as shown in the specific examples. The magnetic yoke has a first extending portion that extends obliquely with respect to the optical axis of the lens at a light emitting portion of the objective lens, and the magnetic coil is also wound around the extending portion. preferable. The magnetic yoke may further include a second extending portion facing the first extending portion via the optical axis of the lens. The magnetic flux generated from the coil of the first extending portion can be drawn by the second extending portion.

According to a sixth aspect of the present invention, a magneto-optical head according to the fifth aspect; an arm supporting the magneto-optical head and moving the magneto-optical head with respect to the information recording medium;
There is provided an apparatus comprising: Since this device can apply a high magnetic field to an information recording medium, it is very suitable for recording and reproduction on a magneto-optical recording medium that needs to apply a magnetic field to a minute area. Further, since the magneto-optical head is small, light, and thin, the transfer rate and access time can be reduced, and high-speed recording and reproduction can be performed. The optical device of the present invention includes a plurality of magneto-optical heads and can record or reproduce data on a plurality of optical disks simultaneously.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific examples of an optical head and a reproducing apparatus according to the present invention will be specifically described with reference to the drawings, but the present invention is not limited thereto.

First Embodiment [Slider] FIG. 1 is an overall perspective view of a flying optical head 30 according to an embodiment of the present invention. The optical head 30 has a slider 11, and a recess 11 a is formed in a slider surface 11 b of the slider 11 facing the optical disk 15. Normally, in the case of a flying optical head, it is necessary to attach various elements constituting the optical head to the slider 11. However, if these elements are simply attached to the slider, those elements become an obstacle in hydrodynamics. In the present invention, in order to avoid this problem, a concave portion 11a is secured in the slider 11, and various elements are accommodated therein. Further, a number of elements are provided between the flying surface 11b of the slider 11 and the element (here, the lens 8) so that the element constituting the optical head is not damaged even if the slider 11 collides with the magneto-optical disk 15 (information recording medium). It is desirable to provide an interval of at least nm.

The concave portion 11a of the slider 11 is covered with a lens support plate 32 made of transparent plastic for supporting the objective lens 8. The slider 11 is connected to a gimbal 14 (arm) that supports the slider 11. In this specific example, the slider 11 is made of zirconia. In FIG. 1, the recess 11 a is exaggerated for the purpose of illustration, but the recess 11 a of the slider is not shown.
a, that is, the chip on which various elements are formed is approximately 200 μm, while the size of the slider 11 is approximately 1 mm square. When the magneto-optical disk 15 rotates, the slider 11 floats, and the optical head 30 is positioned at a desired position on the magneto-optical disk by tracking servo and focusing servo described later. The surface 11 b of the slider 11 has Al ₂ O ₃
Alternatively, SIO ₂ may be applied as a protective layer.

FIG. 2 is a cutaway perspective view of the slider 11 for explaining the inside of the concave portion 11a of the slider 11. In FIG. 2, a schematic side view as viewed from the direction A is shown in FIG. 3, and a schematic plan view as viewed from above is shown in FIG.
As shown in FIGS. 2 to 4, the optical head 30 includes the microactuator 9 and the GaAs substrate 2 that are sequentially stacked on the bottom surface 11 c of the concave portion 11 a of the slider 11. Ga
On an As substrate 2, a semiconductor laser 1, a triangular deflection mirror 10, and detectors 3, 4, and 5 comprising photodiodes
And a drive circuit 19 for the magnetic coil formed monolithically using a semiconductor process. The method for forming them will be described later in detail. First, each element constituting the optical head 30 housed in the slider will be described.

[Tracking and Focusing Actuator] The microactuator 9 is provided with a detector 4 to be described later so that the laser beam (laser spot) emitted from the laser 1 can be focused on the magneto-optical disk 15 with a predetermined spot size. The GaAs substrate 2 is moved in the vertical direction (vertical direction in FIG. 3) based on the detection signal from. By this movement, the laser light is properly focused on the magneto-optical disk 15. Various types of micro-actuators that move up and down in this way are known. For example, IEEE (1997)
-7803-3744 / 97 (p378-379)
Comb drive actuator as described in (Elec
trostatic comb-drive actuator) can be used and reference can be made to this reference for details.

The optical head 30 of this specific example has a triangular deflecting mirror 10 for reflecting the laser beam emitted from the laser 1 at a predetermined track center of the magneto-optical disk 15 in addition to the microactuator 9. Face 2a
And a micro mirror 38 having an actuator function. The micro mirror 38 is, as shown in FIG.
A vertical spring (vertic) is provided substantially at the center of the back surface
al spring) 38a, reflecting surface 2a
An electric field is generated between a pair of electrodes (not shown) provided on the support wall 38b opposed to the corner of the back surface of the substrate and the back surface of the reflection surface 2a. Due to the magnitude and polarity of the electric field, the reflection surface 2a swings in the longitudinal direction (the direction of the arrow α in FIG. 4) with the spring 38a as the swing axis. By the swing of the reflecting mirror 10a, the light is emitted from the semiconductor laser 1 and the reflecting mirror 10a
The laser light reflected from the disk 15 can be finely moved in the radial direction of the disk 15. The swing of the reflecting mirror 2a can position the laser spot at the center position of a desired track based on tracking signals from detectors 3 and 5 described later.

The micromirror 38 is formed by forming an electrode and forming a photomask layer (Phot
ore (oresist sacrificial layer), reactive ion etching (RIE), and deposition of spring metal. The manufacturing process of such a micromirror is described in, for example, “Sensor and Actuato
rs "A66 (1998), pp. 144-149, and this document can be referred to.
In this specific example, the reflecting mirrors 10a (and 10b) are formed by evaporating gold. The surface of the reflecting mirror 10a may be curved with a predetermined curvature in order to shape the spot shape of the laser light reflected therefrom into a circular shape.

[Laser Light Source] The oscillation wavelength of the semiconductor laser 1 is determined according to the magneto-optical disk 15 on which recording or reproduction is performed.
A laser with an oscillation wavelength of 650 nm is preferred. For example, G
aN, GaAs, AlGaAs, AlGaAsP, Zn
A semiconductor laser such as Se can be used. From a manufacturing standpoint, a semiconductor laser made of the same material as the substrate 2 is desirable because it can be easily formed on a substrate through a dry process used in a semiconductor process. Therefore, in this specific example, the n-type AlGaAs, the n-type AlGaAs,
A GaAs semiconductor laser (red laser) 1 in which GaAs and p-type AlGaAs are stacked is provided. As described later, a blue laser capable of short-wavelength oscillation uses a sapphire substrate, and the sapphire substrate has a high intensity and can be used as a slider as it is. If the substrate 2 can be processed as the slider 11 as it is, the operations such as bonding and the accompanying positioning can be omitted, so that the manufacturing process can be simplified and the optical head can be reduced in size and weight.

[Objective Lens] The objective lens 8 is supported by a lens support plate 32 as shown in FIG. As described above, in order to prevent the lens 8 from being damaged when the slider 11 comes into contact with the magneto-optical disk 15, the support plate 32 is set so that the upper end of the lens 8 is located slightly below the floating surface 11b of the slider 11. Is attached to the slider 11. The lens 8 and the support plate 32 can be integrally formed by injection-molding plastic. As the lens 8, a high NA lens such as a SIL (Solid Immersion Lens) may be used.

[Magnetic Field Applying Apparatus] FIG. 5 is an enlarged view of the objective lens 8 shown in FIGS. A patterned copper wire 18 is wound around the lens 8 around the lens optical axis. An electric current is applied to the copper wire 18 to function as a magnetic coil (7). The copper wire 18 may be formed on a lens or a yoke described later by vapor deposition of copper, or the copper wire may be directly bonded on the lens or the yoke.

Generally, when recording (or reproducing) information on the magneto-optical disk 15, it is necessary to efficiently apply a magnetic field to the recording area of the disk 15. Since the intensity of the magnetic field generated from the copper wire 18 is inversely proportional to the distance between the recording film of the magneto-optical disk 15 and the copper wire 18, the copper wire 18 is positioned closest to the magneto-optical disk 15, that is, the light emitting portion 8b of the lens. It is provided in the vicinity. On the other hand, it is desirable to suppress the heat generated by flowing a current through the copper wire 18.
Since the length of the copper wire becomes the resistance as a heat source, it is desirable to wind the wire as shown in FIG. 4 in order to minimize the copper wire length. Further, it is desirable to arrange the copper wire 18 so that the copper wire 18 is not irradiated with the laser beam.

As shown in FIG. 5, the lens 8 includes a light incident portion 8a on the lower surface of the lens 8 and a light emitting portion 8b on the upper surface of the lens.
, Except for a yoke 40 made of a ferromagnetic material, for example, permalloy (FeNi alloy). York 4
The end of the light emitting portion 8b on the side of 0 protrudes upward (in the optical axis direction of the lens) to form a ring-shaped wall 40a. Since the copper wire 18 constituting the magnetic coil is a so-called air-core coil, the magnetic field intensity is limited. Therefore, in order to increase the magnetic flux density of the magnetic field generated near the light emitting portion 8b, the yoke 40
Is provided. The yoke 80 can be partially coated with a ferromagnetic material around the lens by vapor deposition, sputtering, plating, or the like. Since the ferromagnetic material is a metal such as permalloy, it has a heat radiation effect, and has an advantage that heat generated by the magnetic coil and heat generated by laser beam irradiation can be radiated. Further, the lens may be covered with ceramic to prevent the temperature of the lens from rising.

When it is difficult to integrate the lens 8 and the magnetic coil copper wire 18, the flying height of the slider 11 is increased, and a coil printed on a transparent substrate is used to connect the slider 11 to the magneto-optical disk 15. It may be inserted in the middle. In this case, it suffices that only the central portion of the coil be transparent. Therefore, instead of a transparent substrate, a hole may be formed in a thin plate of permalloy only for the passage of the light beam, and the coil may be wound therearound. In this case, the coil is located on the disk 15 side.

The drive circuit 19 for the magnetic coil 7 composed of the copper wire 18 is provided on the substrate 2 as shown in FIGS. This is because if the drive circuit for the magnetic coil is provided not on the flying head 30 but on the main body side of the recording / reproducing apparatus, the wiring connecting the magnetic coil and the drive circuit becomes longer, the impedance becomes higher, and the magnetic field drive speed decreases. This is because According to the present invention, the magnetic coil drive circuit 19 can also be formed integrally with other elements on the substrate 2 by a semiconductor process. In order to dissipate the heat generated from the drive circuit 19 to the slider 11, the drive circuit 19 is coated with a metal having a high thermal conductivity (for example, Cu, Au, Ag, or the like) or contained in these metal blocks. preferable.

[Light Guide Portion] As shown in FIG. 3, the laser light emitted from the semiconductor laser 1 is reflected by the reflecting mirror 10a of the triangular deflecting mirror 10, condensed by the objective lens 8, and is reflected by the objective lens 8. A predetermined recording area (not shown) of the magnetic disk 15 is irradiated. The reflected light (reproduced light) from the recording area of the magneto-optical disk 15 passes through the objective lens 8 again and is reflected by the reflecting mirror 10b of the deflecting mirror 10. Here, FIG.
As shown in FIGS. 3 and 3, S on the substrate 2 on the side of the reflecting mirror 2b.
transparent dielectric 6 as iNx or SiO ₂ is deposited to form a prism. Therefore, as shown in FIG. 3, the return light from the disk 15 enters the transparent dielectric 6 and is reflected by the reflecting mirror 2b, and then reflected again by the inner surface (upper surface) of the transparent dielectric 6 and detected. Incident on the vessel 3 (4, 5). That is, the transparent dielectric 6 guides the reproduction laser light to the detectors 3 to 5. Here, the transparent dielectric 6 can be formed on the substrate 2 by using a semiconductor process, for example, by sputtering or vapor deposition. Detector 3 ~
In order to optimize the optical path to 5, the transparent dielectric film can be laminated little by little while detecting the amount of light received by the detectors 3 to 5.

By the way, as shown in FIG.
At b, minute grooves are formed at predetermined intervals in the inclination direction of the reflecting mirror 10b (horizontal direction in the drawing), thereby forming the diffraction grating 46. The diffraction grating 46 separates the laser light transmitted through the lens 8 into three directions by diffraction, and makes the separated laser lights incident on the detectors 3, 4, and 5, respectively. Of the laser light emitted from the diffraction grating 46, the 0th-order diffracted light is sent to the central detector 4, the + 1st-order light is sent to the detector 3,
The next light respectively goes to the detector 5.

In this specific example, the reflecting mirror 2b and the transparent dielectric layer 6 function as a light guide. The transparent dielectric layer 6 may be omitted, and the tilt angle of the reflecting mirror 10b may be adjusted so that the return light from the disk 15 is directly guided to the detectors 3 to 6. In this case, the reflecting mirror 2b functions as a light guide.

[Photodetector] As shown in FIG.
Numerals 5 are arranged in the direction in which the deflecting mirror 10 extends (Y direction in the drawing), and are respectively embedded in the substrate 2. Each detector is a detector having two light receiving sections divided, and the detectors 3 and 5 have two light receiving sections divided in the Y direction in the figure. The detector 4 has two light receiving sections divided in the X direction in the figure, and is used for detecting an autofocus signal. In this specific example, the detectors 3 to 5
Are formed from GaAs photodiodes. S
When an i-substrate is used, a Si photodiode can be formed.

Next, focusing and tracking of the magneto-optical disk 15 using the detectors 3 to 5 will be described. Usually, a guide groove for tracking is formed on the magneto-optical disk 15, and the tracking is performed such that both ends of the light spot condensed on the recording film surface evenly cover a pair of grooves defining the track. It is done by being adjusted. Also in this specific example, the magneto-optical disk 15 has a guide groove (not shown), and the tracking of the magneto-optical disk 15 will be specifically described. When the light spot is located exactly at the center of the track, the amount of light reflected from the grooves on both sides becomes equal, and thus the amount of light received by the light receiving sections 3a and 3b of the two-divided detector 3 (or 5) as shown in FIG. Are equal. When the light spot is deviated to one of the guide grooves, the light receiving amounts of the light receiving units 3a and 3b are different.
By swinging the reflecting mirror 10a of the micromirror 38 so as to balance the light receiving amounts of the light receiving units 3a and 3b, the tracking shift amount can be corrected. Thus, the differential signal of the light receiving sections 3a and 3b of the detector 3 becomes a tracking error signal. Since a similar signal can be obtained in the detector 5, the light receiving sections 3a and 5a of the detectors 3 and 5 can be obtained.
, And the sum signal of the light receiving sections 3b and 5b, respectively, a difference between the sum signals is obtained (differential signal), and the differential signal can be used as a tracking error signal.

In the detector 4 for detecting a focus error signal, when the focus is just focused, the detector 4
The light receiving amounts from the two light receiving units 4a and 4b become equal. Therefore, a focus error signal can be detected by obtaining a differential signal from the two light receiving units.

In addition to the tracking by the guide groove of the magneto-optical disk, there is also a sample servo system in which tracking is performed by pits formed on the disk. Tracking control is similarly performed using the detectors 3 and 4 of the optical head 30. it can.

The light reflected from the disk is split into a p-wave and an s-wave by a diffraction grating 46 in FIG. Since the p-wave is detected by the detector 3 and the s-wave is detected by the detector 5, a magneto-optical signal is obtained from the differential signal.

[Gimbal (Optical Head Arm)] Returning to FIG. 1, the power supply wiring to the semiconductor laser 1, the power supply and signal wiring to the detector, and the power supply and signal lines to the microactuator 9 are shown in FIG. Printed wiring as shown. Usually, in the case of a magnetic disk recording / reproducing apparatus, since the wiring is not printed, there is a problem that the tension of the wiring hinders the movement of the gimbal 14. However, in the case of the present invention, the printed wiring allows the slider 11 to float stably. The bonding between the printed wiring and the circuit on the slider can be performed using an Au wire. When the slider 11 stably floats, the disk 15 and the lens 8 supported in the slider
Also, since the optical path length between the detectors 3 to 8 also becomes a constant value, it is possible to position the lens 8 in advance in accordance with the flying height, and the focus of the lens 8 is always constant. Can be omitted.

The gimbal 14 normally vibrates violently due to the rotation of the disk. In order to prevent the printed wiring from peeling off, it is desirable to interpose a substance such as Cr, which enhances the adhesion to the printed wiring, to the gimbal 14 or the suspension by sputtering or plating.

[Manufacturing process] Next, on a GaAs substrate,
A method for forming the semiconductor laser 1, the deflection mirror 10, the detectors 3 to 5, and the transparent dielectric 6 will be described. First, an MO is deposited on the back surface of an n-type GaAs substrate having a (100) plane.
An Au electrode is provided by CVD. Next, the deflection mirror 1
0 can be formed by the following dry process. For example, the central portion of the substrate is etched by anisotropic etching to leave a protruding portion in a triangular prism shape. Next, mask the portions other than the triangular prism-shaped protrusions by photolithography,
Au is deposited on the reflecting surface 10b of the protruding portion. The micro mirror 38 can be formed by the method described above. The reflecting mirror 10a on the micro mirror 38 can be formed by depositing gold or aluminum. In order to fabricate the semiconductor laser 1 and the detectors 3 to 5 on an n-type GaAs substrate, the flat portions other than the deflection mirror 10 are dry-etched. Next, on the portion of the substrate that constitutes the semiconductor laser 1, n
-Type AlGaAs, GaAs, p-type AlGaAs, and A
u electrodes are sequentially grown using MOCVD. The parts constituting the detectors 3, 4, and 5 of the substrate are n-type GaAs
s, p-type GaAs and Au electrodes can be formed by MOCVD. After forming the detectors 3-5, the transparent dielectric 6 can be deposited by evaporation or sputtering as described above.

[Configuration of Recording / Reproducing Apparatus] FIG. 8 shows an example of the configuration of a magneto-optical disk reproducing apparatus 100 having the optical head of the present invention. Flying slider 1 of optical head 30 of the present invention
1 can reduce the thickness. Therefore, as shown in FIG. 8, it is possible to support a plurality of disks 60 coaxially at predetermined intervals as in a magnetic disk device, and to provide the flying heads 30 on both surfaces of each disk. The suspension 62 supporting the flying head 30 is moved by a voice motor 64 or the like, and a microactuator (not shown) can be used for fine movement.

Second Specific Example Another specific example of the optical head according to the present invention will be described with reference to FIG. 6, and the same parts as in the first specific example will be denoted by the same reference numerals and description thereof will be omitted. In the first specific example, the detectors 3 to 3 arranged in the Y direction using the diffraction grating 46 engraved on the reflecting mirror 10b
5 guided the light. In this specific example, the diffraction grating 46 is not used, and the micro prism 16 as shown in FIG.
A description will be given of the optical head 50 using the optical head. This optical head 50
As shown in FIG. 7, the reflected reproduction light 51 from the magneto-optical disk 15 enters the microprism 16 instead of the reflecting mirror 10b, and is split by the light separation surface 16a. That is, the p-light oscillating in parallel with the plane of incidence of the reproduction light 51 with respect to the microprism 16 passes through the light separation surface 16a and enters the detector 52. Also, s vibrates perpendicularly to the plane of incidence of the reproduction light 51 with respect to the microprism 16.
The light is reflected on the light separation surface 16a of the microprism 16, travels inside the microprism, is reflected on the reflection surface 16b, and then enters the detector 54. Here, the detectors 52 and 54 are two-divided detectors similar to the detectors 3 and 5 used in the first specific example.

Third Specific Example This specific example shows an optical head 90 in which the semiconductor substrate 2 used in the first specific example is processed as a slider 11. As shown in FIG. 9, GaAs or sapphire is processed into the shape of the slider 11, and then a concave portion 11a is formed. The semiconductor laser 1 and the deflection mirror 10 having the micromirror 38 are provided on the bottom 11c of the recess 11a.
The detectors 3 to 5 and the transparent dielectric 6 can be formed in the same manner as in Example 1. Since the semiconductor material generally has insufficient mechanical strength, a material having excellent wear resistance such as diamond-like carbon is coated as the coating layer 92. For example, when a sapphire laser (blue laser) is used as the semiconductor laser 1, a sapphire substrate can be used as a slider material and a semiconductor laser can be directly grown thereon. Since sapphire is hard, it is preferable in terms of mechanical strength.

In this specific example, since the slider 11 also serves as the substrate, there is no need to align the surface of the slider with the semiconductor substrate, and the manufacturing process can be simplified. Further, the number of parts can be reduced, and the optical head 90 can be further reduced in size and weight.

In this case, the micro-actuator for the focus servo may be provided at a connection portion between the slider 11 and the gimbal or at the gimbal, or by positioning the lens 8 in advance according to the flying height of the slider. The servo may be omitted.

Fourth Specific Example In this specific example, an example of a magnetic coil and a yoke different from the magnetic coil and the yoke provided on the lens 8 of the optical head 30 of the first specific example will be described. In the example shown in FIG. 10, the yoke 40 that covers the objective lens 8 in the example shown in FIG.
Only the annular yoke 98 was provided inside the magnetic coil 7.

In the example shown in FIG. 11, the yoke 102
The yoke 102 covers only a part of the lens in the circumferential direction, and the yoke 102 extends in the optical axis direction of the lens near the light emitting portion of the lens 8 to define a yoke wall 104. This yoke wall 104
Is provided only in a part in the circumferential direction near the light emitting portion. The magnetic coil 7 is wound so as to surround the yoke wall 104. Even with such a configuration, a magnetic field can be applied to the light emitting portion by the magnetic coil 7. As the length of the magnetic coil increases, the response of the applied magnetic field decreases. Since the magnetic coil 7 having this configuration is relatively short, it has excellent responsiveness to an applied magnetic field.

Fifth Specific Example In this example, further different configuration examples of the magnetic coil and the yoke are shown. As shown in FIG. 12, the yoke 102
As in the first specific example, the lens is covered except for the light entrance and exit sections. Further, the yoke 10 is removed from the slope of the lens.
6 protrudes and extends so as to obliquely intersect the optical axis of the lens. Also, the yoke 108 extends so as to face the yoke 106 so as to obliquely intersect the optical axis of the lens. Then, the magnetic coil 110
Is wound around only one of the square yokes 106. With this configuration, the magnetic flux (indicated by a dashed line in the figure) generated from the magnetic coil 106 wound around one yoke 106 travels obliquely to the optical axis, and the other yoke 1
08 sucked. Since the magnetic flux in the oblique direction includes a component of the magnetic flux in the vertical direction (optical axis direction), it is effective for perpendicular magnetic recording. In addition, since the magnetic flux can be applied from an oblique direction, the restriction on the installation position of the magnetic coil can be eased and the design of the magneto-optical head can be facilitated.

As a modification of FIG. 12, as shown in the sectional view of the lens of FIG. 13, it is possible to embed a bar-shaped magnetic flux suction side yoke 112 and a coiled yoke 114 in the lens 8.

Sixth Embodiment This embodiment is directed to the detectors 3 to 3 in the optical head of the first embodiment.
14 (A) and 14 (B) show an example in which 5 is provided on the same side as the semiconductor laser 1 with respect to the deflection mirror 10. In this configuration, the light emitted from the semiconductor laser 1 is reflected by the reflecting surface 10 a of the deflecting mirror,
After that, the light passes through the lens 8 again and is incident on the diffraction grating 46 ′ engraved above the reflection surface 10a. Where +
The light diffracted into the first-order, zero-order, and -1st-order light directly enters the detectors 3, 4, and 5, respectively. This configuration has the advantage that the optical head can be further miniaturized by halving the chip or substrate area.

Seventh Specific Example FIG. 15 shows another example of the configuration of the yoke. As in the specific example 4, the permalloy yoke 120 covers the area of the objective lens 8 excluding the light incident area and the light emitting area, but the light emitting area 122 is formed in a slit shape.
The slit width is shorter than the wavelength of the laser light. For this reason, under the conditions of the near field (Near field), the slit 122
The evanescent light exudes through this, and recording or reproduction with the evanescent light becomes possible. This enables recording and reproduction of extremely small magnetic domains.

Eighth Embodiment In the above embodiment, a lightweight and compact optical recording / reproducing head for high-density recording / reproduction has been described. However, in order to further increase the density, the objective lens 8 shown in FIG. It is effective to provide a hemispherical lens 20 as shown in FIG. One or more hemispherical lenses may be used. As described above, since the flying head floats aerodynamically stably, a control mechanism for adjusting the focus of the hemispherical lens is not required, and the objective lens 8 and the hemispherical lens 20 can be fixed.

When the hemispherical lens 20 shown in FIG. 16 is used in combination with an objective lens, since the alignment between the lens 8 and the hemispherical lens 20 is important, the hemispherical lens 20 as shown in FIG. It is preferable to provide the microactuator 21 and perform focusing by the microactuator 21.

Ninth Embodiment In this embodiment, recording or reproduction is performed by the optical head of the present invention.
A configuration example of the magneto-optical disk 15 that can be produced will be described. 0.4
Polycarbonate having land and groove of 5 μm width
A first nitride dielectric film of about 60 nm on a
Tb which is a conductive layer ₂₂Fe₆₈Co₁₀About 2 perpendicular magnetization films
00 nm, first Al reflective film 10 nm, second nitride dielectric
15 nm, the second magnetic layer Gd₂₂Fe₆₈Co₁₀2
0 nm and about 60 nm of the third nitride dielectric are laminated respectively.
You. The groove depth is 45 nm. The flying height of the flying head is 3
If it is about 00 nm, the height of the land and groove
The difference is about 45nm, so the floating stability of the slider
Does not inhibit sex.

This disk sample had a degree of vacuum of 3 × 10 ^−7.
After evacuating to Torr or less, it was produced by a high frequency sputtering method.
The sputtering power of each layer was 1 kW.
As a target used for sputtering, it is preferable to use a target having a diameter of 5 inches or more in order to achieve a uniform film thickness over the entire 5-inch substrate. When the substrate revolves around its own axis, the uniformity of the film thickness is further improved. The configuration of the disk is such that one of the high-density micro magnetic domains recorded in the first magnetic layer located in the portion where the temperature is raised most near the center of the light spot is the second magnetic layer.
This is an example of a disk configuration of a magnetic domain expansion reproduction system in which a large reproduction signal is obtained by being enlargedly transferred to a magnetic layer. This type of magneto-optical disk is disclosed in WO98 / 02876 and WO98 / 02877 of the present applicant, and these publications can be referred to. Second magnetic layer Tb ₂₂ Fe
The Curie temperature of ₆₈ Co ₁₀ is about 270 ° C., and the Curie temperature of the first magnetic layer Gd ₂₂ Fe ₆₈ Co ₁₀ is 350
It is around ° C.

If recording and reproduction can be performed with a small magnetic field, the data transfer rate can be increased. For that, the first
When a Gd ₂₂ Fe ₅₈ Co ₂₀ magnetic film (recording auxiliary layer) is laminated on the substrate side of the magnetic layer, the magnetic field required for recording is 200 (O
e) was found to be reduced to 100 (Oe). G
d ₂₂ Fe ₅₈ Co ₂₀ magnetic film shows a plane magnetization at the time of recording, exhibits perpendicular magnetization at the time of reproduction. Since this recording auxiliary layer loses its effect as the distance from the recording head increases, it is preferable to arrange the recording auxiliary layer at a position near the disk surface.

In order to reduce the reproducing magnetic field for magnetic domain expansion reproduction, the necessary reproducing magnetic field is reduced to about 200 (O
It has been found that e) can be reduced to about 100 (Oe). Here, sputter etching refers to inverting the polarity of the sputter electrode to sputter the surface of the recording film once attached. Therefore, the second in this case
Since the thickness of the dielectric film is removed by the etching, the second
It is necessary to sputter the dielectric layer extra thick. In the present embodiment, it was known that the second dielectric was cut off by about 5 nm by sputter etching at 500 W for about 1 minute, so the thickness of the second dielectric was set to 20 nm.

The optical head and the optical device capable of recording or reproducing information according to the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples, and various modifications and improvements are possible. is there.

For example, in the above specific example, a magneto-optical disk has been described as an example of an information recording medium, but a high-density read-only disk (ROM), for example, a CD-ROM
Alternatively, reproduction of a DVD-ROM is also possible. When reproducing a magneto-optical signal, the differential signal between the detectors 3 and 5 was used. In the case of reproducing a ROM, a sum signal of the detectors 3 and 5 is used as a reproduced signal. . In the case of a ROM that does not use a magneto-optical signal, a detector may be arranged as shown in FIG.

In the above specific example, an example has been described in which focus and tracking servo are performed by the actuator 9 and the micromirror 38. However, the position of the objective lens 8 may be controlled by using an actuator. Further, tracking control can be performed even if the arrangement shown in FIG. 4 is rotated by 90 degrees with respect to the disk 15 and the swing direction of the reflecting mirror 10a is changed in the vertical direction. Further, it is also possible to make the substrate movable up, down, left and right by the microactuator 9 installed below the substrate 2, and to execute both focus servo and tracking servo simultaneously.

Further, as a modification, as shown in FIG. 18, the semiconductor laser 1 can be arranged vertically. In this case, the deflecting mirror 10 becomes unnecessary, but the height of the optical head is increased and the position adjustment becomes relatively difficult.

Further, in the above specific example, the lens 8 is used for light collection, but light collection using a grating is also possible. In this case, the grating has a lower light-gathering ability than the lens, but the weight is light, so that the access speed of the head can be increased.

In the eighth specific example, the hemispherical lens is provided between the objective lens and the disk 15. However, in the configuration shown in FIGS. 2 to 4, the second hemispherical lens is provided between the semiconductor laser 1 and the reflecting mirror 10a.
An objective lens (not shown) may be provided. Second
The beam diameter can be reduced by the objective lens, whereby the objective lens 8 can be reduced in size, and the slider 11 can be made thinner.

Further, an electric field can be generated near the yoke by applying a voltage to the yoke shown in FIGS. In this way, when the flying head slides on the magneto-optical disk, it becomes possible to attract the lubricant, dust and dirt peeled off from the disk surface to the yoke by electrostatic attraction. Thereby, contamination of the light exit surface of the lens can be suppressed.

[0075]

The optical head according to the present invention can provide a light and small head like a magnetic head of a hard disk.
Therefore, the transfer rate and the access speed are greatly improved. The slider can be made thinner than a conventional optical head. In addition, by forming the slider from a semiconductor material, an extremely precise and small optical head can be manufactured through a semiconductor process. INDUSTRIAL APPLICABILITY The optical head and optical device of the present invention are extremely effective for recording and reproducing information recorded on a high-density information recording medium, particularly a magneto-optical recording medium.

[Brief description of the drawings]

FIG. 1 is an overall perspective view of a flying optical head 30 according to a specific example of the present invention.

FIG. 2 is a cutaway perspective view of the slider for explaining each element of the optical head formed in a concave portion of the slider.

FIG. 3 is a schematic side view of the optical head viewed from a direction A in FIG. 2;

FIG. 4 is a schematic plan view of the optical head viewed from above in FIG. 2;

FIG. 5 is a conceptual diagram showing a configuration of a yoke and a magnetic coil coated on an objective lens.

FIG. 6 is a diagram showing a schematic configuration of an optical head according to a second specific example of the present invention.

FIG. 7 is an explanatory diagram showing an optical path of laser light in a microprism used in the optical head shown in FIG.

FIG. 8 is a diagram showing a schematic configuration of a recording / reproducing apparatus of the present invention.

FIG. 9 is a diagram showing a schematic configuration of an optical head according to a third specific example of the present invention, in which the slider is made of a substrate material.

FIG. 10 is a conceptual diagram showing another configuration example of a yoke and a magnetic coil coated on an objective lens.

FIG. 11 is a conceptual diagram showing another configuration example of a yoke and a magnetic coil coated on an objective lens.

FIG. 12 is a conceptual diagram showing another configuration example of a yoke and a magnetic coil coated on an objective lens. In this example, a magnetic flux is emitted obliquely with respect to an optical axis.

FIG. 13 is a schematic sectional view showing a configuration example of a yoke and a magnetic coil filled in an objective lens.

FIG. 14A is a plan view showing a modification of the first specific example shown in FIG. 4, showing an arrangement in which the detector is on the same side of the deflection mirror as the semiconductor laser;
FIG. 15B is a side view of the optical head shown in FIG.

FIG. 15 is a schematic perspective view showing another configuration example of a yoke and a magnetic coil covered by an objective lens. In this example, recording or reproduction is performed using evanescent light.

FIG. 16 is a schematic perspective view showing an optical head of an eighth specific example, in which a hemispherical lens is provided between the objective lens and the disk 1.

FIG. 17 shows a configuration further provided with a hemispherical lens vertical movement actuator in FIG.

FIG. 18 is a modification of the first embodiment and shows an optical head having a structure in which a semiconductor laser is placed vertically.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 laser 2 substrate 3 to 5 split detector 6 transparent dielectric 7 coil 8 lens 9 microactuator 10 deflection mirror 11 slider 12 diffraction grating 13 printed wiring 14 gimbal 15 disk 16 microprism 17 patterned yoke 18 patterned copper wire 19 Magnetic head drive circuit 20 Hemisphere lens 32 Lens support plate 40 Yoke

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 11/105 571 G11B 11/105 571D

Claims (34)

[Claims] 1. An optical head for use in an apparatus for recording or reproducing information by irradiating an information recording medium with light, comprising: a laser light source for irradiating the information recording medium with a laser beam; A detector for detecting the reflected laser light; and a light guide unit for guiding the laser light reflected from the information recording medium to the detector, wherein the laser light source, the detector and the light guide unit are provided. An optical head integrally formed on a common substrate. 2. The optical head according to claim 1, further comprising an objective lens for converging laser light from a laser light source on an information recording medium, and a magnetic coil coated on the objective lens. 3. The optical head according to claim 1, wherein the light reflected from the information recording medium is directed in an in-plane direction of the substrate by the light guide section. 4. The optical head according to claim 1, wherein the light guide includes a first reflecting mirror and a prism for directing a laser beam reflected from the information recording medium to a photodetector. 5. The apparatus according to claim 4, wherein the photodetector has a plurality of detectors, and the first reflector has a diffraction grating on a surface of the first reflector, which divides the laser beam into the respective detectors. Light head. 6. The optical head according to claim 4, wherein the light guide section has a second reflecting mirror for directing a laser beam from a laser light source to the information recording medium. 7. The optical head according to claim 6, further comprising a lens disposed between the laser light source and the second reflecting mirror. 8. The optical head according to claim 1, wherein the light guide section includes a prism for directing a laser beam reflected from the information recording medium to a photodetector. 9. The optical head according to claim 8, wherein the photodetector has a plurality of detectors, and the prism divides laser light reflected from the information recording medium into the respective detectors. 10. The optical head according to claim 1, further comprising a microactuator for adjusting a path of a laser beam applied to the information recording medium. 11. The optical head according to claim 1, further comprising a drive circuit for driving the magnetic coil, wherein the drive circuit is formed integrally on the substrate. 12. The optical head according to claim 1, wherein the substrate is processed into a slider shape. 13. The optical head according to claim 6, wherein the second reflecting mirror is curved at a predetermined curvature to shape the spot shape of the laser beam reflected by the second reflecting mirror into a circle. 14. The optical head according to claim 1, further comprising a yoke coated on the objective lens. 15. An apparatus comprising: the optical head according to claim 2; and an arm that supports the optical head and moves the optical head with respect to the information recording medium. 16. The apparatus according to claim 15, further comprising an electric wiring for transmitting a driving signal or a driving voltage to the optical head, which is printed on the arm. 17. The apparatus of claim 16, wherein said electrical wiring is printed on the arm via chrome. 18. An optical head used in an apparatus for recording or reproducing information by irradiating light on an information recording medium, comprising: a laser light source for irradiating the information recording medium with laser light; A detector for detecting the reflected laser light; an optical guide for guiding the laser light reflected from the information recording medium to the detector; and a slider floating on the information recording medium, A slider having a concave portion formed on the side facing the information recording medium; and an optical head having the laser light source, the detector, and the light guide unit integrally formed on the bottom of the concave portion of the slider. 19. The optical head according to claim 18, wherein the slider comprises a semiconductor substrate. 20. The apparatus according to claim 18, further comprising an objective lens for converging a laser beam from a laser light source on an information recording medium, and a lens support for supporting the lens on the slider recess. Light head. 21. The optical head according to claim 20, wherein the objective lens and the lens support are integrally formed. 22. The optical head according to claim 20, further comprising a magnetic coil coated on the objective lens. 23. The optical head according to claim 22, further comprising a yoke coated on the objective lens. 24. A kind of layer selected from silicone, alumina and diamond-like carbon is formed on the side of the slider facing the information recording medium.
9. The optical head according to 8. 25. An apparatus for recording or reproducing information on an information recording medium, comprising: the optical head according to claim 23; and an arm for supporting the optical head and moving the optical head with respect to the information recording medium. 26. A magneto-optical head for use in an apparatus for recording or reproducing information by irradiating an information recording medium with light, comprising: a slider flying above the information recording medium; A laser light source for irradiating the recording medium with laser light; a detector provided on the slider, for detecting the laser light reflected from the information recording medium; and a laser light source provided on the slider, A magneto-optical head comprising: an objective lens for condensing a laser beam on an information recording medium; a magnetic coil provided on the objective lens and a magnetic material coated on the objective lens. 27. The magneto-optical head according to claim 26, wherein the magnetic body covers an objective lens so as to partition an optical path of the laser light. 28. The magneto-optical head according to claim 26, wherein the magnetic body has an extending portion extending from the lens in the optical axis direction of the lens at a light emitting portion of the objective lens. 29. The magnetic body has a first extending portion that extends obliquely with respect to the optical axis of the lens at a light emitting portion of the objective lens, and the magnetic coil is also wound around the extending portion. 27. The magneto-optical head according to claim 26, wherein: 30. The magneto-optical head according to claim 29, wherein the magnetic body further includes a second extension provided to face the first extension via the optical axis of the lens. 31. The magneto-optical head according to claim 26, further comprising a voltage applying device for applying a voltage to the magnetic material to generate an electric field near the yoke. 32. The magneto-optical head according to claim 26, wherein the magnetic coil is wound around an optical axis of the objective lens. 33. The magneto-optical head according to claim 26, further comprising an optical guide provided on the slider and for guiding a laser beam to the detector. 34. A magneto-optical head according to claim 26;
An arm that supports the magneto-optical head and moves the magneto-optical head with respect to the information recording medium, and records or reproduces information on the information recording medium.