JPH07230638A - Magneto-optical head device - Google Patents

Abstract

PURPOSE:To obtain the magneto-optical head device to be used for a magneto- optical recording and/or reproducing device suitable for miniaturization. CONSTITUTION:A light beam generating part 11, an objective lens 15, a splitting optical element 12 and a photodetector 16 are arranged to form an optical axis of a light beam emitted from the light beam generating part 11, an optical axis from the splitting optical element 12 to a reflecting mirror 13, an optical axis from the reflecting mirror 13 to the objective lens 15 and an optical axis from the splitting optical element 12 to the photodetector 16 on the same plane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical head device. In particular, the present invention is suitable for miniaturization of magneto-optical recording and / or
Alternatively, the present invention relates to a magneto-optical head device used in a reproducing device.

[0002]

2. Description of the Related Art An optical head device is used for recording or reproducing an information signal on an optical recording medium such as a magneto-optical recording medium. The optical head device is constructed, for example, as shown in FIG. The optical head device described below will be described by taking a disk-shaped optical recording medium as an optical recording medium, which will be simply referred to as an optical disc. Figure 7,
In FIG. 8, the optical head device 1 has a semiconductor laser element 2 as a light source, a reflection mirror 3, an objective lens 5, a beam splitter 6, a Wollaston prism 7, and a photodetector 8. Although not shown, the optical head device 1 is provided with an actuator that drives the objective lens 5 in the focusing direction and the tracking direction. From the semiconductor laser element 2, when recording an information signal on the optical disc 4 based on a drive signal from a drive circuit (not shown), a light beam of a high output level is used when a light beam of a high output level is read from the optical disc 4. A light beam with a low output level is output.

The reflection mirror 3 is composed of a total reflection mirror or the like, and is in the Z-axis direction in FIG. 7, that is, the semiconductor laser element 2.
Inclined by 45 ° with respect to the optical axis of the light beam emitted from
It is arranged on the optical axis of the objective lens 5. The objective lens 5 transmits the light beam reflected by the reflection mirror 3 to the optical disc 4
Focus on the recording surface of. The objective lens 5 is an aspherical lens formed of a material having a light transmitting property. The beam splitter 6 separates the light beam emitted from the semiconductor laser element 2 and the light beam incident via the objective lens 5, and deflects the optical path of the light beam incident via the objective lens 5 by 90 °. . The beam splitter 6 is composed of, for example, a polarization beam splitter. The Wollaston prism 7 generates a plurality of light beams from the light beams separated by the beam splitter 6. The Wollaston prism 7 is formed by bonding two prisms made of an optical material having optical anisotropy, as disclosed in US Pat. No. 4,771,414. The Wollaston prism 7 is attached to the exit surface of the beam splitter 6, that is, one side surface of the beam splitter 6 as shown in FIG. The photodetector 8 has a plurality of photodetectors that respectively receive the plurality of light beams generated by the Wollaston prism 7. The photodetector 8 is arranged at a position where the plurality of light beams emitted from the Wollaston prism 7 are focused. The optical disc 4 is rotationally driven by a spindle motor 9 at a constant linear velocity or a constant angular velocity.

In the optical head device 1 thus constructed, the light beam emitted from the semiconductor laser element 2 is
90 by the reflecting mirror 3 via the beam splitter 6
The optical path is deflected and guided to the objective lens 5. The objective lens 5 focuses the light beam emitted from the semiconductor laser element 2 on the recording surface of the optical disc 4. The light beam reflected by the recording surface of the optical disc 5 is again guided into the optical head device 1 via the objective lens 5. The light beam incident through the objective lens 5 is reflected by the beam splitter 6
Is separated from the light beam emitted from the semiconductor laser element 2, and the optical path is deflected by 90 ° and emitted from the Wollaston prism 7. A plurality of light beams are emitted from the Wollaston prism 7 and are received by the photodetector 8. Based on the output signal output from the photodetector 8, various reproduction signals of the information signal recorded on the optical disc 4 and various error signals based on focusing error and tracking error are generated. A servo signal for driving the actuator is generated based on the focusing error signal and the tracking error signal.

In the optical head device 1, as shown in FIG. 8, an optical path or an optical axis from the semiconductor laser device 2 to the beam splitter 6 to the reflection mirror, and from the reflection mirror 3 to the beam splitter 6 are provided. The optical path to the photodetector 8 or the optical axis of the light beam is parallel to the recording surface of the optical disc 4. In other words, the semiconductor laser element 2, the beam splitter 6, the Wollaston prism 7, and the photodetector 8 are arranged in a plane parallel to the recording surface of the optical disc 4. On the other hand, the optical path or optical axis from the reflection mirror 3 to the objective lens 5 is perpendicular to the signal recording surface of the optical disc 4. The optical head device 1 is fed by an unillustrated feeding mechanism from the inner circumference side to the outer circumference side of the optical disk 4, or from the outer circumference side to the inner circumference side, that is, in the X-axis direction in FIG. At this time, the spot of the light beam focused on the recording surface of the optical disc 4 by the objective lens 5 passes through the center of the track on the recording surface of the optical disc 4 which is rotationally driven by the spindle motor 9 as shown in FIG. Move on one straight line.

[0006]

However, in the optical head device 1 thus constructed, the semiconductor laser element 2, the beam splitter 6, the Wollaston prism 7 and the photodetector 8 are parallel to the recording surface of the optical disc 4. The optical head device 1 and the spindle motor 9 may interfere with each other when the optical head device 1 is sent to the inner peripheral side of the optical disk 4, especially when it is sent to the innermost peripheral side. There is That is, as shown in FIG. 82, since the photodetector 8 is arranged on the side close to the spindle motor 9 in the optical head device 1, when the optical head device 1 is sent to the innermost side of the optical disc 4, There is a possibility that the portion where the photodetector 8 is provided may collide with the spindle motor 9.

In order to solve this problem, the photodetector 8
May be arranged on the opposite side in FIG. 8, that is, at a position symmetrical with respect to the optical axis of the light beam emitted from the semiconductor laser element 2. However, in this case, when the optical head device 1 is sent to the outermost peripheral side of the optical disc 4, the optical head device 1 projects to the outside from the outer peripheral end portion of the optical disc 4, and thus recording and / or recording using the optical head device 1 is performed. Alternatively, the size of the entire playback device is increased. In the optical head device 1 shown in FIGS. 7 and 8, the light beam reflected by the optical disk 4 is separated and deflected by the beam splitter 6, and then is irradiated onto the photodetector 8 via the Wollaston prism 7. It is configured to. Therefore, the optical path length from the beam splitter 6 to the photodetector 8 becomes long, which leads to an increase in the size of the optical head device 1 as a whole. Further, since the number of parts itself constituting the optical head device 1 is large, a large number of man-hours are required for assembly and adjustment, which causes a problem such as an increase in cost.

In view of the above points, it is an object of the present invention to provide a magneto-optical head device which is small in size and does not interfere with a spindle motor or the like.

[0009]

According to the present invention, the above object is to provide a light beam generating means for emitting a light beam and a light beam emitted from the light beam generating means for converging at a point on the optical axis. An objective lens, a separation optical element for separating the light beam emitted from the light beam generating means and the light beam incident through the objective lens, and the light beam emitted from the light beam generating means by 90 ° A reflecting mirror for deflecting and guiding to the objective lens, and a photodetector for receiving the light beam incident through the objective lens separated by the separating optical element are provided, and the light beam generating means is provided. The optical axis of the emitted light beam, the optical axis from the separation optical element to the reflection mirror, the optical axis from the reflection mirror to the objective lens, and the separation optical element to the photodetector As the optical axis constitutes the same plane throughout, the light beam generating means, the objective lens, and arranging the separating optical element and the photodetector, the magneto-optical head device, is achieved.

The photodetector may be arranged on the optical axis of the light beam emitted from the light beam generating means deflected by the separation optical element.

The light beam generating means emits a light beam, a light detector for receiving the light beam incident through the objective lens separated by the separation optical element, and a light detector for emitting the light beam. A further separating optical element for separating the light beam and the light beam incident through the objective lens and guiding the light beam to the photodetector may be provided.

The separating optical element outputs a light beam incident through the first prism formed of glass and arranged on the output side of the light beam emitted from the light beam generating means, and the objective lens. And a second prism formed of an optical material having optical anisotropy located on the side.

The separating optical element outputs the light beam incident through the first prism formed of glass and arranged on the output side of the light beam emitted from the light beam generating means, and the objective lens. Is formed of an optical material having optical anisotropy located on the side, and has an emission surface inclined by a predetermined angle with respect to the emission surface of the light beam emitted from the beam generating means of the first prism. A second prism and a dielectric multilayer film provided between the first and second prisms are provided, and the first and second prisms are bonded via the dielectric multilayer film. May be.

Further, the above object is, in the present invention, a light beam generating means for emitting a light beam, and an objective lens for converging the light beam emitted from the light beam generating means at one point on the optical axis. A separation optical element for deflecting the light beam emitted from the light beam generating means and separating the light beam emitted from the light beam generating means from the light beam incident through the objective lens; The light beam emitted from the light beam generation means deflected by the element is deflected by 90 ° and guided to the objective lens, and the light beam incident through the objective lens that has passed through the separation optical element is received. And an optical axis of the light beam emitted from the light beam generating means, an optical axis from the separation optical element to the reflection mirror, The light beam generating means, the objective lens, the separation optical element and the light so that the optical axis from the reflecting mirror to the objective lens and the optical axis from the separation optical element to the photodetector constitute the same plane. It is also achieved by a magneto-optical head device in which a detector is arranged.

Further, according to the present invention, the above object is to provide a light source for emitting a light beam, a light beam generating means having a first photodetector for error detection, and a light beam emitting means for emitting the light beam. An objective lens for focusing the focused light beam at a point on the optical axis, a separation optical element for separating the light beam emitted from the light beam generating means and the light beam incident through the objective lens, and the light The light beam emitted from the beam generator is deflected by 90 ° and guided to the objective lens, and the light beam incident through the objective lens that has passed through the separation optical element is received to detect a reproduction signal. A second photodetector, and the light beam incident through the objective lens is guided to the first photodetector by the separation optical element and the second photodetector. And the optical axis of the light beam emitted from the light beam generating means, the optical axis from the separation optical element to the reflection mirror, and the light from the reflection mirror to the objective lens. A magneto-optical head in which the light beam generating means, the objective lens, the separation optical element and the photodetector are arranged so that the axis and the optical axis from the separation optical element to the photodetector form the same plane. It is also achieved by the device.

[0016]

According to the magneto-optical head device of the present invention, the entire device can be made compact. Further, since the size of the objective lens in the plane direction perpendicular to the optical axis can be reduced, it does not interfere with other mechanisms when the magneto-optical head device is fed by the feeding mechanism.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A magneto-optical head device according to the present invention will be described in detail below with reference to the drawings. The magneto-optical head device shown in each of the embodiments described below will be described as an example in which it is used in a recording and / or reproducing device of a magneto-optical disk. First, a magneto-optical head device as a first embodiment according to the present invention will be described in detail with reference to FIGS. 1 and 2, a magneto-optical head device 10 includes a light emitting and receiving composite element 11, a beam splitter 12, a total reflection mirror 13, an objective lens 15,
And a photodetector 16.

The light emitting / receiving composite element 11 has a substrate 11a, a semiconductor laser element 11b, an optical prism 11c, and light detecting portions 11d and 11b. The substrate 11a is formed of a material such as Si, and the photodetection portions 11d and 11e are formed on the substrate 11a by a semiconductor process. Each of these photodetection sections 11d and 11e is composed of three strip-shaped light receiving sections that are parallel to each other. By performing arithmetic processing using the output signals from these photodetectors 11d and 11e, error signals such as a focusing error signal and a tracking error signal, an address signal recorded in advance on the magneto-optical disk 14 and the like are generated. . The semiconductor laser device 11b includes the substrate 11
It is provided on a.

The optical prism 11c has a quadrangular prism shape, and the side surface facing the semiconductor laser element 11b is formed as an inclined surface having a predetermined angle. A dielectric multi-layer film is coated on the inclined surface. The dielectric multi-layer film reflects the light beam emitted from the semiconductor laser element 11b, and the optical beam reflected by the beam splitter 12 is reflected by the optical prism 11c. Allow to penetrate inside. The optical prism 11c is fixed on the substrate 11a with an adhesive or the like so as to cover the photodetection portions 11d and 11e formed on the substrate 11a. The light beam reflected by the beam splitter 12 passes through the inclined surface of the optical prism 11c and is guided into the prism 11c.
The light is repeatedly received in c and is received by the photodetectors 11d and 11e. The light emitting / receiving composite element 11 is arranged above the magneto-optical head device 10, that is, on the magneto-optical disk 14 side.

The beam splitter 12 includes a first optical prism 12b and a second optical prism 12 as shown in FIG.
c and the first and second optical prisms 12b and 12c
And a dielectric multi-layer film 12a provided between and. The first optical prism 12b is formed in a triangular prism shape using an optical material having no optical anisotropy. Second
The optical prism 12c is formed in a quadrangular prism shape using an optical material having optical anisotropy (birefringence). Of the light beams incident on the beam splitter 12 via the objective lens 15, two light beams having a predetermined opening angle by the second optical prism 12c based on the light beam transmitted through the second optical prism 12c, Ordinary rays and extraordinary rays are generated. The first optical prism 12b is located on the output end side of the light beam emitted from the semiconductor laser 11b, and the second optical prism 12c is located on the output end side of the light beam incident via the objective lens 15. The dielectric multi-layered film 12a is bonded to form a hexahedron.

In the first embodiment, assuming that the wavelength λ of the light beam emitted from the semiconductor laser device 11b as the light source is λ = 780 nm, the first optical prism 12 is used.
b is OHARA Inc. having a refractive index of 1.825. Made SF
The second optical prism 1 formed by using 03 (trade name)
2d has a refractive index of 2.258 for ordinary rays and 2.178 for extraordinary rays of lithium niobate (Li
It is formed using NbO ₃ ). When the second optical prism 12c is formed using LiNbO ₃ , Li
Since NbO ₃ is a material having a large refractive index, the light beam that passes through the beam splitter 12 and is emitted toward the photodetector 16 is bent and emitted from the optical axis from the reflection mirror 13 to the photodetector 16. At the same time, the emitted light beam includes astigmatism. Further, as will be described later, the two light beams interfere with each other on the two photodetector portions on the photodetector 16.

In order to solve these problems, as shown in FIG. 3, the emission surface side of the light beam incident through the objective lens 15 of the second optical prism 12c is located on the first optical prism 1 side.
It is formed on an inclined surface 12c-1 which is inclined so as not to be parallel to the emission surface 12b-1 of 2b. As a result, the two light beams emitted from the second optical prism 12c are emitted so as to be positioned above and below in FIG. 1 with the optical axis from the reflection mirror 13 to the photodetector 16 interposed therebetween.
In FIG. 1, the upper side is the ordinary ray and the lower side is the extraordinary ray.

The dielectric multilayer film 12a is provided between the inclined surface of the first optical prism 12b and the inclined surface of the second optical prism 12c. The dielectric multilayer film 12a has a 90-degree optical path for the light beam emitted from the light emitting and receiving composite element 11.
The light beam incident through the objective lens 15 is deflected by 90 degrees, and a part of the light beam incident through the objective lens 15 is reflected by 90 degrees to be transmitted to the photodetection sections 11d and 11e of the composite element 11 for emitting and receiving light. Through a part of the photodetector 16
Lead to. After the dielectric multilayer film 12a is formed on the inclined surface of one of the first or second optical prisms 12b and 12c by coating or the like, the second optical prism 12c detects light from the reflection mirror 13. In a state where the crystal optical axis of the second optical prism 12c is inclined by 45 ° in a plane perpendicular to the optical axis reaching the container 16, the inclined surface of the first optical prism 12b and the second optical prism 12 are
The beam splitter 12 as shown in FIG. 3 is formed by bonding the inclined surfaces of c to each other.

The total reflection mirror 13 is the beam splitter 1
It is arranged at a position below the objective lens 15 and on the optical axis of the objective lens 15 tilted by 45 ° with respect to the optical axis of the light beam emitted from the semiconductor laser element 11b deflected by 2. The objective lens 15 is an aspherical lens formed of glass or a synthetic resin material having light transmittance.
The objective lens 15 focuses the light beam reflected by the reflection mirror 14 on the recording surface of the magneto-optical disk 14. The objective lens 15 is used by the actuator (not shown) of the magneto-optical head device 10 to drive the objective lens 1
5 is moved in a direction parallel to the optical axis of the objective lens 5, that is, the focusing direction, and a plane direction orthogonal to the optical axis of the objective lens 15, that is, the tracking direction. The objective lens 15 is
When the information signal is recorded on the magneto-optical disk 33 or the information signal recorded on the magneto-optical disk 14 is reproduced, the actuator is moved in the focusing direction and the tracking direction so as to cancel the focusing error and the tracking error.

The photodetector 16 receives the two light beams having a predetermined opening angle, the ordinary ray and the extraordinary ray, by the second optical prism 12c of the beam splitter 12, respectively.
It has a photodetection section 16a and a second photodetection section 16b. The reproduction signal of the information signal recorded on the magneto-optical disk 14 is obtained by taking the difference between the output signal of the first photodetector 16a and the output signal of the second photodetector 16b. The magneto-optical head device 10 as described above is fed by an unillustrated feeding mechanism in the inner and outer circumferential directions of the magneto-optical disk 14 and in the direction perpendicular to the paper surface of FIG. The magneto-optical disk 14 is rotationally driven by the spindle motor 17 shown in FIG. 2 at a constant linear velocity or a constant angular velocity.

The magneto-optical head device 1 thus constructed
At 0, the light beam emitted from the combined light emitting and receiving element 11 is reflected by the inclined surface of the optical prism 11c and guided to the beam splitter 12. The light beam incident on the beam splitter 12 has its optical path deflected by 90 ° by the dielectric multilayer film 12a and is emitted toward the reflection mirror 13. The light beam output from the beam splitter 12 has its optical path deflected by 90 ° again by the reflection mirror 13 and is condensed on the recording surface of the magneto-optical disk 14 by the objective lens 15. At this time, the objective lens 15 is moved by the actuator in the focusing direction and the tracking direction so as to cancel the focusing error and the tracking error. The light beam applied to the recording surface of the magneto-optical disk 14 is reflected by the recording surface of the magneto-optical disk 14 and enters the magneto-optical head device 10 again through the objective lens.

The light beam incident through the objective lens 15, that is, the reflected beam, is deflected by the beam splitter 12 by 90 ° in the optical path of a part of the light beam, and is guided to the light emitting / receiving composite element 11, while the remaining light beam is guided. The reflected light beam passes through the beam splitter 12. When the remaining reflected beam passes through the optical prism 12c, two light beams, an ordinary ray and an extraordinary ray, are generated. The two light beams generated by the beam splitter 12 are reflected by the photodetector 1
The light is received by each of the six photodetectors 16a and 16b. On the other hand, the reflected beam that is deflected toward the light emitting and receiving composite element 11 passes through the inclined surface of the optical prism 11c of the light emitting and receiving composite element 11 and is received by the photodetectors 11d and 11e. As a result, error signals such as a focusing error signal and a tracking error signal are generated by performing arithmetic processing using output signals from the photodetectors 11d and 11e, and an address signal recorded on the magneto-optical disk 14 and the like. Is generated. The reproduction signal of the information signal recorded on the magneto-optical disk 14 can be obtained by calculating the difference between the output signals of the photodetectors 16a and 16b of the photodetector 16.

As shown in FIG. 1, in the magneto-optical head device 10 according to the first embodiment, a combined light emitting and receiving element 11,
The beam splitter 12, the reflection mirror 13, and the photodetector 16 are arranged in a plane perpendicular to the recording surface of the magneto-optical disk 14 in FIG. In other words, the photodetector 1 passes from the reflection mirror 13 through the beam splitter 12.
The above-described components are arranged in a single plane including the optical axis reaching 6 and the optical axis reaching the beam splitter 12 from the combined light emitting and receiving element 11 and the optical axis reaching the objective lens 15 from the reflection mirror 13. . As a result, in the magneto-optical head device 10 according to the first embodiment, the width in the ZX plane in FIG. 2 can be reduced, so the magneto-optical head device 10
It is possible to avoid contact with the spindle motor 17 when the sheet is fed in the inner peripheral direction of the magneto-optical disk 14 by the feeding mechanism. Further, when the recording and / or reproducing apparatus is fed in the outer peripheral direction of the magneto-optical disk 14, the portion protruding from the outer peripheral edge of the magneto-optical disk 14 is reduced, which leads to an increase in the size of the entire recording and / or reproducing apparatus. It can be avoided.

Next, a magneto-optical head device 20 according to a second embodiment of the present invention will be described with reference to FIG. It should be noted that the same reference numerals as those in the first embodiment are given to the portions common to those in the first embodiment, and the detailed description is based on the description of the first embodiment. The second embodiment differs from the first embodiment only in the position of the arrangement of the combined light emitting and receiving elements in the magneto-optical head device, and the other parts are configured in the same manner as the first embodiment. ing.

In the first embodiment, the light emitting / receiving composite element 11 is used.
Was arranged on the magneto-optical disk 14 side of the magneto-optical head device 10. On the other hand, in the second embodiment, the light emitting and receiving composite element 11 is arranged at the lower side in FIG.
It is arranged on the side opposite to the side facing 4. By arranging the light emitting and receiving composite element 11 in such a position,
The distance between the surface of the magneto-optical head device 20 facing the magneto-optical disk 14 and the magneto-optical disk 14 can be increased. As a result, even if the magneto-optical disk 14 moves up and down due to the warp of the disk itself, it is possible to avoid contact with the magneto-optical head device.

Next, a magneto-optical head device according to a third embodiment of the present invention will be described in detail with reference to FIG. As shown in FIG. 5, the magneto-optical head device 30 according to the third embodiment includes a semiconductor laser element 31 and a beam splitter 3.
5, a total reflection mirror 32, an objective lens 34, a Wollaston prism 36, and a photodetector 37. When recording an information signal from the semiconductor laser element 31 as a light source on the optical disc 33 based on a drive signal from a drive circuit (not shown), when a light beam with a high output level reads the information signal from the optical disc 33. A light beam with a low output level is output to the.

The total reflection mirror 32 includes the beam splitter 3
The optical path of the light beam emitted from the semiconductor laser element 31 that has passed through 5 is deflected by 90 °, and is 45 ° with respect to the optical axis of the light beam emitted from the semiconductor laser element 31.
It is arranged below the objective lens 34 in an inclined state and on the optical axis of the objective lens 34. The objective lens 34 is
The light beam reflected by the total reflection mirror 32 is focused on the recording film of the magneto-optical disk 33. The objective lens 34 is an aspherical lens formed of glass or a material having light transmittance. The objective lens 34 is moved in a direction parallel to the optical axis of the objective lens 34, that is, a focusing direction and a plane direction orthogonal to the optical axis of the objective lens 34 by an actuator (not shown) provided in the magneto-optical head device 30, that is, Moved in the tracking direction. The objective lens 34 is moved in the focusing direction and the tracking direction by an actuator so as to cancel the focusing error and the tracking error at the time of recording the information signal on the magneto-optical disc 33 or reproducing the information signal recorded on the magneto-optical disc 33. It

The beam splitter 35 is formed in a hexahedron shape by bonding two triangular prism-shaped optical prisms via a dielectric multilayer film 35a. The beam splitter 35 includes a light beam emitted from the semiconductor laser device 31 by the dielectric multilayer film 35a,
The light beam incident into the magneto-optical head device 30 via the objective lens 34 is separated, and the optical path of the light beam incident via the objective lens 34 is deflected by 90 ° and output toward the photodetector 37. . A Wollaston prism 36 is attached to the output surface of the light beam incident through the objective lens 34 of the beam splitter 35 using an adhesive or the like.

The Wollaston prism 36 is formed by bonding two optical prisms 36a and 36b together. These optical prisms 36a and 36b are
Each of them is made of an optical material having optical anisotropy, for example, lithium niobate (LiNbO ₃ ). The optical prism 36a on the side on which the light beam emitted from the beam splitter 35 is incident has the crystal optical axis P of the light beam.
It is rotated by 45 ° with respect to the plane of polarization, and the crystal optical axis of the optical prism 36b on the output side of the light beam is rotated by 90 ° with respect to the P-polarized plane of the light beam. In this state, the optical prisms 36a and 36b are bonded together. The Wollaston prism 36 generates at least two light beams of P and S polarization components based on the light beam emitted from the beam splitter 35.

The photodetector 37 has a plurality of photodetectors. These light detectors allow the Wollaston prism 3
Each of the at least two light beams generated by 6 is received. A reproduction signal of an information signal recorded on the magneto-optical disk 33 by performing an arithmetic process using an output signal from each photodetector, an error signal such as a focusing error signal and a tracking error signal, and the magneto-optical disk 33 in advance. A recorded address signal or the like is generated. Although not shown, the semiconductor laser device 3 in FIG.
In the optical path between the beam splitter 1 and the beam splitter 35, a diffraction grating is provided on the emission optical axis of the semiconductor laser element 31. This diffraction grating converts the light beam emitted from the semiconductor laser device 31 into at least three light beams, that is, 0
Separated into the first-order diffracted light and the plus-minus first-order diffracted light. The plus / minus first-order diffracted light is used to detect a tracking error. The 0th-order diffracted light is used for detecting a focusing error and reproducing an information signal recorded on the magneto-optical disk 33. However, in FIG. 5, only one light beam is shown for simplification.

The magneto-optical head device 3 thus constructed.
At 0, the light beam emitted from the semiconductor laser device 31 is transmitted through the beam splitter 35 to the total reflection mirror 3
Guided to 2. The light beam with which the total reflection mirror 32 is irradiated has its optical path deflected by 90 ° by the total reflection mirror 32, and is condensed on the recording surface of the magneto-optical disk 33 by the objective lens 34. The light beam applied to the magneto-optical disk 33 is reflected by the recording surface of the magneto-optical disk 33 and again passes through the objective lens 34 to the magneto-optical head device 3 again.
It is incident within 0.

The light beam incident through the objective lens 34, that is, the reflected beam, has an optical path of 90 ° by the dielectric multilayer film 35a of the beam splitter 35.
The light is deflected and focused on each photodetector of the photodetector 37 via the Wollaston prism 36. The Wollaston prism 36 generates three light beams based on the incident reflected beam and irradiates the photodetector 37 with the light beams. Photo detector 3
By performing arithmetic processing using the output signals from the respective photodetection units of No. 7, error signals such as a focusing error signal and a tracking error signal are generated, and an address signal recorded on the magneto-optical disk 14 is generated. It The reproduction signal of the information signal recorded on the magneto-optical disk 33 can be obtained by taking the difference between the output signals of the two photodetectors of the photodetector 37.

As shown in FIG. 5, in the magneto-optical head device 30 according to the third embodiment, the semiconductor laser element 31,
The beam splitter 35, the reflection mirror 32, and the photodetector 37 are arranged on a surface perpendicular to the recording surface of the magneto-optical disk 33 in FIG. In other words, the optical axis from the semiconductor laser element 31 to the total reflection mirror 32 via the beam splitter 35, the optical axis from the total reflection mirror 32 to the objective lens 34, and the optical axis from the beam splitter 35 to the photodetector 37. The above-described components are arranged in a single plane including As a result, in the magneto-optical head device 30 according to the third embodiment, the width in the ZY plane in FIG. 5 can be reduced, and therefore the same effect as that of the first embodiment can be obtained.

Next, a magneto-optical head device 40 according to a fourth embodiment of the present invention will be described in detail with reference to FIG. In addition, the same reference numerals are given to the portions common to those of the first embodiment, and the detailed description is based on the description of the first embodiment. In FIG. 6, a magneto-optical head device 40
Includes a light emitting and receiving composite element 41. The light emitting / receiving composite element 41 includes a semiconductor laser 41a and a hologram element 41.
b, a photodetector 41c. The semiconductor laser element 41a as a light source records an information signal on the optical disc 14 based on a drive signal from a drive circuit (not shown), and when a light beam with a high output level reads the information signal from the optical disc 14. Emits a light beam with a low output level. The semiconductor laser element 41a is provided on a common base together with the photodetector 41c, and is housed in one package.

The hologram element 41b is fixed to the upper surface of the package with an adhesive or the like. The hologram element 41b is made of a glass substrate, and has a hologram 41b ₁ formed on the outer surface thereof and a diffraction grating formed on the back surface side. The diffraction grating formed on the back surface side of the hologram element 41b generates a plurality of light beams for generating a tracking error signal, based on the light beam emitted from the semiconductor laser element 41a, for example, plus / minus first-order diffracted light. It is what is generated.
The hologram 41b-1 formed on the outer surface of the hologram element 41b has two regions having different grating periods.

As will be described later, the portion of the light beam incident through the objective lens 15 that passes through one of the two regions of the hologram 41b-1 having different grating periods is, for example, 1 of the photodetector 41c described later. A portion of the light that has been focused on one photodetector and has passed through the other region is a photodetector 41 to be described later.
The light is focused on another photodetector of c. This hologram 41b
-1 is formed using the method of computer generated hologram. For example, the hologram 41b-
1 is created. The hologram data generated by the computer is transferred to the photoresist on the glass substrate by the electron beam drawing device. A hologram is formed on the glass substrate using the ion beam etching method in which the photoresist is used as a mask and is obliquely incident. The photodetector 41c has a plurality of photodetectors, and by performing arithmetic processing using output signals from these photodetectors, error signals such as a focusing error signal and a tracking error signal are generated.

In the magneto-optical head device 40 according to the fourth embodiment having such a structure, the light beam emitted from the semiconductor laser element 41a is emitted via the hologram element 41b, and the dielectric multilayer of the beam splitter 12 is formed. The optical path is deflected by 90 ° by the film 12a. When the light beam passes through the hologram element 41b, it is separated into at least three light beams of 0th order diffracted light and plus or minus 1st order diffracted light.
In the drawing, one light beam is shown for simplification.

The light beam deflected by the beam splitter 12a is applied to the total reflection mirror 13, and the optical path is again deflected by 90 ° by the total reflection mirror 13. The light beam deflected by 90 ° by the total reflection mirror 13 is condensed on the recording surface of the magneto-optical disk 14 by the objective lens 15. The light beam applied to the magneto-optical disk 14 is reflected by the recording surface of the magneto-optical disk 14 and again enters the magneto-optical head device 40 via the objective lens 15. The light beam that has entered through the objective lens 15, that is, the reflected beam, is reflected by the beam splitter 12.
The optical path of a part of the light beam is deflected by 90 ° and guided to the combined light emitting and receiving element 41, while the remaining reflected light beam passes through the beam splitter 12. When the remaining reflected beam passes through the optical prism 12c, two light beams, an ordinary ray and an extraordinary ray, are generated. The two light beams generated by the beam splitter 12 are received by the photodetectors 16a and 16b of the photodetector 16.

On the other hand, in the reflected beam deflected toward the light emitting and receiving composite element 41, the portion passing through one of the two regions of the hologram 41b-1 of the hologram element 41b having different grating periods is the photodetector 41c. The light is received by one photodetector, and the portion that has passed through the other region is received by another photodetector. As a result, error signals such as a focusing error signal and a tracking error signal are generated by performing arithmetic processing using the output signals from the respective photodetection units of the photodetection unit 41c and recorded on the magneto-optical disk 14. Address signals and the like are generated. The reproduction signal of the information signal recorded on the magneto-optical disk 14 can be obtained by calculating the difference between the output signals of the photodetectors 16a and 16b of the photodetector 16.

As shown in FIG. 6, in the magneto-optical head device 40 according to the fourth embodiment, a combined light emitting and receiving element 41,
The beam splitter 12, the reflection mirror 13, and the photodetector 16 are arranged in the ZY plane, which is a surface perpendicular to the recording surface of the magneto-optical disk 14 in FIG. In other words, it includes the optical axis from the total reflection mirror 13 to the photodetector 16 via the beam splitter 12, the optical axis from the light emitting and receiving composite element 41 to the beam splitter 12, and the optical axis from the total reflection mirror 13 to the objective lens 15. The above-described components are arranged in a single plane. As a result, in the magneto-optical head device 40 according to the fourth embodiment, the width in the ZY plane in FIG. 6 can be reduced, and therefore the same effect as that of the first embodiment can be obtained.

In the present invention, as shown in each of the above-mentioned embodiments, even if the magneto-optical head device is moved in the inner peripheral direction of the magneto-optical disk, it is in contact with the spindle motor for rotating the magneto-optical disk. The point can be solved, and a small-sized magneto-optical head device can be provided. Further, as shown in the first and second embodiments, one of the two optical prisms forming the beam splitter is made of an optical material having optical anisotropy, so that FIG. Since it is not necessary to provide the Wollaston prism of the optical head device shown, not only can the number of parts be reduced, but the optical path length from the beam splitter to the photodetector can be shortened, and the magneto-optical head device can be made more compact. can do.

Furthermore, as in the nineteenth and fourth embodiments, a signal photodetector for reproducing the information signal recorded on the magneto-optical disk and a photodetector for detecting an error signal are provided. CNR (Carrier to Noise) of the signal obtained from the signal photodetector by separately providing
It is possible to obtain a signal with high e Ratio. In this case, since the configuration is as described above, it is possible to avoid increasing the size of the entire magneto-optical head device.
In the above-described embodiments, the magneto-optical head device for recording or reproducing on the magneto-optical recording medium has been described as an example, but the magneto-optical disk and the read-only optical disk (re
ad only type optical dis
It can also be applied to an optical head device that also serves as c). Needless to say, various modifications can be made without departing from the spirit of the present invention.

[0048]

As described above, according to the present invention, it is possible to provide a magneto-optical head device which is small in size and does not interfere with a spindle motor or the like.

[Brief description of drawings]

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

FIG. 2 is a configuration diagram showing a configuration of the magneto-optical head device according to the first embodiment as viewed from above.

FIG. 3 shows a configuration of a beam splitter used in the present invention.

FIG. 4 is a configuration diagram showing a configuration of a magneto-optical head device according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram showing a configuration of a magneto-optical head device according to a third embodiment of the invention.

FIG. 6 is a configuration diagram showing a configuration of a magneto-optical head device according to a fourth embodiment of the invention.

FIG. 7 is a configuration diagram showing a simplified example of an optical head device.

8 is a configuration diagram showing a simplified configuration of the optical head device shown in FIG. 7 when viewed from above.

[Explanation of Codes] 10 Magneto-optical Head Device 11 Emitting and Receiving Composite Element 12 Beam Splitter 13 Total Reflection Mirror 14 Magneto-optical Disk 15 Objective Lens 16 Photo Detector

Claims (12)

[Claims] 1. A light beam generating means for emitting a light beam, an objective lens for focusing the light beam emitted from the light beam generating means on one point on an optical axis, and a light emitted from the light beam generating means. A separating optical element for separating the beam and the light beam incident through the objective lens, and the light beam emitted from the light beam generating means by 90 °
A reflecting mirror for deflecting and guiding to the objective lens, and a photodetector for receiving the light beam incident through the objective lens separated by the separating optical element are provided, and the light beam generating means is provided. The optical axis of the emitted light beam, the optical axis from the separation optical element to the reflection mirror, the optical axis from the reflection mirror to the objective lens, and the optical axis from the separation optical element to the photodetector are on the same plane. The magneto-optical head device is characterized in that the light beam generating means, the objective lens, the separation optical element, and the photodetector are arranged so as to constitute the above. 2. The photodetector is arranged on the optical axis of a light beam emitted from the light beam generating means which is deflected by the separation optical element. Magneto-optical head device. 3. The light beam generation means includes a light source for emitting a light beam, a light detection section for receiving the light beam incident through the objective lens separated by the separation optical element, and an emission from the light source. 2. The magneto-optical head device according to claim 1, further comprising a separation optical element that separates the formed light beam and the light beam incident through the objective lens and guides the separated light beam to the photodetector. 4. The separation optical element comprises a first prism made of glass and arranged on the output side of the light beam emitted from the light beam generating means, and a light beam incident through the objective lens. 2. The magneto-optical head device according to claim 1, wherein the magneto-optical head device comprises a second prism formed of an optical material having optical anisotropy located on the output side of the. 5. The separation optical element comprises a first prism formed of glass arranged on the output side of the light beam emitted from the light beam generating means, and a light beam incident through the objective lens. Is formed of an optical material having optical anisotropy located on the output side of
A second prism having an emission surface inclined by a predetermined angle with respect to the emission surface of the light beam emitted from the beam generating means of the prism.
And a dielectric multilayer film provided between the first and second prisms, and the first and second prisms are provided.
2. The magneto-optical head device according to claim 1, wherein the prism is bonded through the dielectric multilayer film. 6. A light beam generating means for emitting a light beam, an objective lens for focusing the light beam emitted from the light beam generating means on one point on the optical axis, and a light emitted from the light beam generating means. A separating optical element for deflecting the beam and separating a light beam emitted from the light beam generating means and a light beam incident through the objective lens; and the light beam generating means deflected by the separating optical element. A reflecting mirror for deflecting the emitted light beam by 90 ° and guiding it to the objective lens; and a photodetector for receiving the light beam incident through the objective lens that has passed through the separation optical element, and An optical axis of the light beam emitted from the light beam generating means, an optical axis from the separation optical element to the reflection mirror, and from the reflection mirror to the objective lens. The light beam generating means, the objective lens, the separation optical element and the photodetector are arranged so that the optical axis and the optical axis from the separation optical element to the photodetector form the same plane. Magneto-optical head device. 7. The photodetector according to claim 6, wherein the photodetector is arranged on the optical axis of the light beam emitted from the light beam generating means deflected by the separation optical element. Magneto-optical head device. 8. The light beam generating means emits a light beam, a light detector for receiving a light beam incident through the objective lens separated by the separation optical element, and a light detector for emitting the light beam. 7. The magneto-optical head device according to claim 6, further comprising: a further separating optical element that separates the light beam and the light beam incident through the objective lens and guides the separated light beam to the photodetection unit. 9. The separation optical element comprises a first prism made of glass arranged on the output side of the light beam emitted from the light beam generating means, and a light beam incident through the objective lens. 7. The magneto-optical head device according to claim 6, wherein the magneto-optical head device comprises a second prism formed of an optical material having optical anisotropy located on the output side of the. 10. The separation optical element comprises a first prism formed of glass arranged on the output side of the light beam emitted from the light beam generating means, and a light beam incident through the objective lens. Is formed of an optical material having an optical anisotropy located on the output side of the first prism, and an emission surface inclined by a predetermined angle with respect to the emission surface of the light beam emitted from the beam generating means of the first prism. And a dielectric multilayer film provided between the first and second prisms, and the first and second prisms are bonded to each other through the dielectric multilayer film. 7. The magneto-optical head device according to claim 6, wherein 11. A light source for emitting a light beam, a light beam generating means having a first photodetector for error detection, and a light beam emitted from the light beam generating means for focusing on a point on the optical axis. An objective lens, a separation optical element for separating the light beam emitted from the light beam generating means and the light beam incident through the objective lens, and the light beam emitted from the light beam generating means by 90 °
A reflecting mirror for deflecting and guiding the light to the objective lens; and a second photodetector for detecting a reproduction signal for receiving a light beam incident through the objective lens that has passed through the separation optical element, In addition, the light beam incident through the objective lens is separated by the separation optical element into a light beam guided to the first photodetector and a light beam guided to the second photodetector. An optical axis of the light beam emitted from the light beam generating means, an optical axis from the separation optical element to the reflection mirror, an optical axis from the reflection mirror to the objective lens, and the separation optical element to the photodetector A magneto-optical head device characterized in that the light beam generating means, the objective lens, the separation optical element, and the photodetector are arranged such that the optical axes reaching the above-mentioned plane form the same plane. 12. The light beam generating means comprises a further separating optical element for separating the light beam emitted from the light source and the light beam separated by the separating optical element. 11. The magneto-optical head device according to item 11.