JPH08161763A - Optical pickup device - Google Patents

Abstract

PURPOSE: To obtain an optical pickup device in which a coma aberration generated due to the inclination of an optical disk can be corrected in a simple constitution. CONSTITUTION: An incident region is divided radially into four equal parts around the optical axis of a laser beam. An optical disk 1 is irradiated with a laser beam via a four-split optical-rotation plate 7 having an optical-rotation characteristic which optically rotates and radiates the laser beam incident on a direction of optical rotation in which adjacent incident regions are different. Then, its beam of reflected light is separated by a polarization beam splitter 5 and a beam splitter 4 so as to be received by a second photodetector 15. In the second photo-detector 15, its light-receiving region is divided into four parts so as to correspond to the four-split optical-rotation plate 7. As a result, when an inclination is generated in the optical disk 1, a quantity of received light in any light-receiving region on the second photodetector 15 is increased. A skew detection circuit 12 detects a difference in the quantity of received light, the inclination of the optical disk 1 is detected, and a moving unit 6 which is constituted integrally with an objective lens 8 is moved and controlled via a skew control circuit 17 according to the inclination.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device suitable for use as a reproducing device, a recording device and a recording / reproducing device for all kinds of optical discs such as so-called compact discs, magneto-optical discs, write-once and video discs. In particular, by detecting the tilt of the optical disc during recording or reproduction and moving the objective lens or the like in any direction following this tilt, it is possible to always irradiate the laser beam at the optimum angle. The present invention relates to an optical pickup device.

[0002]

2. Description of the Related Art Conventionally, there has been known an optical pickup device capable of irradiating a laser beam at a desired angle by moving an objective lens following the inclination of an optical disc during recording or reproduction. . This optical pickup device has a structure as shown in FIG. 16, and a laser beam is emitted from the laser light source 101 when recording or reproducing. The laser beam is collimated by the collimator lens 102, and the movable unit 104
Is incident on the objective lens 105.

If the objective lens 105 has a high aperture ratio and a short wavelength laser beam is used, the thicker optical disc and the thinner optical disc are the thicker optical discs. Coma aberration easily occurs due to the inclination of the optical axis. When the above-mentioned coma aberration occurs, the laser beam is not vertically irradiated onto the optical disc 100, so that the forward path and the backward path of the laser beam are different from each other and scattering of the reflected light or the like occurs, resulting in recording data, a focus error signal, and tracking. It becomes difficult to accurately detect an error signal or the like.

On the other hand, in the thin optical disk, theoretically, the coma aberration is unlikely to occur, but the thin optical disk easily bends, so that the actual coma aberration easily occurs. In order to make it difficult for the coma aberration to occur regardless of the thickness of the optical disc 100, an objective lens that can correct the coma aberration according to the disc thickness may be used. However, such an objective lens is costly. It becomes high and not practical.

For this reason, a very ordinary objective lens is used as the objective lens 105. In this conventional optical pickup device, the tilt of the optical disc 100 is detected and the coma aberration is eliminated as described below. I am trying to correct it. That is, when the laser beam is incident, the objective lens 105 focuses the laser beam and irradiates it on the optical disc 100. Reflected light is generated by irradiating the optical disc 100 with a laser beam, and this reflected light is radiated to a photodetector (not shown) through the objective lens 105 to detect recording data, tracking error signal, focus error signal, etc. Used for. The tracking error signal and the focus error signal are respectively supplied to the movable unit 104.

As shown in FIG. 17, the movable unit 104 has a substantially rectangular front shape, and a pair of drive coils 112 are provided inside the movable unit 104 along both short sides. Two magnets 111 are provided in proximity to the one drive coil 112. Further, a pair of arm fixing portions 104a and 104b are provided facing each other at approximately the center of both longitudinal sides of the movable unit 104, and each of the arm fixing portions 104a and 104b has two pairs. A total of four elastic arms 106 are fixed at one end. The other end of each elastic arm 106 is fixed to the fixed wall 110.

Therefore, the movable unit 104 can move in the radial direction (tracking direction) of the disk or in the focus direction, which is a direction perpendicular to the radial direction, and is supported at four points. Movable unit 1
04 is designed to prevent rolling which causes unstable movement. In such a movable unit 104,
When the tracking error signal and the focus error signal are supplied to each drive coil 112 of the movable unit 104, based on the magnetic field generated by each magnet 111 and the tracking error signal and the focus error signal supplied to each drive coil 112. As a result, a moving force in the tracking direction or the focus direction is generated.

As a result, the movable unit 104 can be moved in the direction in which the tracking error and the focus error are corrected, and it is possible to always perform recording and reproduction with just track and just focus. On the other hand, the skew detection circuit 103 irradiates the optical disc 100 with a laser beam separately from the laser light source 101 to receive the reflected light, and based on the received light amount of the reflected light, the disc is caused by deflection or eccentricity of the disc. Is detected and the skew detection signal is supplied to the biaxial drive system 107.

When the skew detection signal is supplied to the biaxial drive system 107, the laser light source 10 responds accordingly.
The entire optical pickup device including the collimator lens 102 and the movable unit 104 is controlled to be tilted.
As a result, the inclination of the optical disc 100 is tracked,
The optical disc 100 can be always irradiated with the laser beam vertically, and the coma aberration can be corrected and the recorded data or the like can be accurately detected.

Next, as a conventional optical pickup device, as shown in FIG. 18, the objective lens 1 is placed in a movable unit 120.
It is also known that the laser light source 121 is incorporated together with 25. This optical pickup device includes a laser light source 121
The laser beam emitted from the first reflection mirror 122
Then, the light is reflected by the second reflection mirror 124 and is incident on the objective lens 125. The objective lens 125 is an ordinary objective lens similar to the objective lens 105 described above, and focuses the laser beam to irradiate the optical disc 127.

Then, the optical disk 127 is irradiated with a laser beam to generate reflected light. The reflected light is used to detect recording data, tracking error, focus error, and the like. The movable unit 120
As shown in FIG. 19, the front surface has a substantially rectangular shape, and a pair of drive coils 131 and 132 are provided inside thereof along both short sides. Further, two magnets 133 and 134 are provided close to the two drive coils 131 and 132, respectively. Further, a pair of arm fixing portions 120a and 120b are provided facing each other at approximately the center of both longitudinal sides of the movable unit 120.
One end of a total of four elastic arms 128 is fixed to each of the arm fixing portions 120a and 120b, and two ends are fixed to the respective arm fixing portions 120a and 120b, and the other ends of the elastic arms 128 are fixed to the fixing wall 130, respectively. .

Therefore, since the movable unit 120 is movable in the tracking direction or the focus direction of the disk and is supported at four points, it is possible to prevent the movable unit 104 from rolling which causes unstable movement. You can do it. In such a movable unit 120, when the tracking error signal and the focus error signal are supplied to the drive coils 131 and 132 of the movable unit 120, the magnets 13 are generated.
Magnetic field generated by 3,134 and each drive coil 131, 1
A moving force in the tracking direction or the focus direction is generated based on the tracking error signal and the focus error signal supplied to 32.

As a result, the movable unit 120 can be moved in the direction in which the tracking error and the focus error are corrected, and it is possible to always perform the recording and reproduction with the just track and the just focus. On the other hand, the skew detection circuit 126 irradiates the optical disc 127 with a laser beam separately from the laser light source 121 to receive reflected light, and based on the received light amount of the reflected light, the disc is generated due to deflection or eccentricity of the disc. Is detected and the skew detection signal is supplied to the biaxial drive system 126.

When the skew detection signal is supplied, the biaxial drive system 126 controls the entire optical pickup device to incline accordingly. As a result, the optical disc 100 can be always irradiated with the laser beam vertically by following the inclination of the optical disc 100, and the coma aberration can be corrected and the recorded data or the like can be accurately detected.

[0015]

However, in the conventional optical pickup device, in addition to the movable units 104 and 120, a detection system (laser light source and skew detection circuits 103 and 123) for detecting the inclination of the disk is provided. In addition to the above, a two-axis drive system 10 including gears and motors
7, 126, the entire optical pickup device is tilted according to the detected tilt of the disc.

Therefore, there is a problem that the structure becomes large-scale, the optical pickup device becomes large in size, and the cost becomes high. Further, since the optical pickup device cannot be tilted except in the two-axis directions, there is a dead zone in which coma aberration cannot be corrected depending on how the disc is tilted. Further, since the coma aberration is mechanically corrected by the biaxial drive systems 107 and 126, the reaction may be slow and the coma may be increased rather.

Furthermore, what is actually desired to be corrected is the angle of the laser beam emitted from the objective lenses 105 and 125 to the optical discs 100 and 127, but the skew detection circuits 103 and 123 are to be corrected by the objective lenses 105 and 12.
5, a laser beam different from the laser beam applied to the optical discs 100, 127 from 5 is newly added.
0, 127 is irradiated, and the tilt of the disk is detected based on the reflected light. Therefore, there is an error between the inclination of the disk detected by the skew detection circuits 103 and 123 and the inclination of the disk that is actually occurring (there is an error because the detection is performed at different positions). , I couldn't really correct coma aberration. This problem becomes more remarkable as the diameter of the disk becomes smaller.

The present invention has been made in view of the above-mentioned problems, and the optical pickup device itself can be miniaturized by a simple structure and can be manufactured at a low cost, and a disc in all directions can be accurately and responsively. An object is to provide an optical pickup device capable of correcting coma aberration due to tilt.

[0019]

An optical pickup device according to the present invention is a laser light source for emitting a laser beam for irradiating an optical disc, and a light beam having a first deflection direction. A deflecting beam splitter that reflects light having a second deflecting direction orthogonal to the direction. Further, a laser beam passing through the polarization beam splitter and an incident area of reflected light generated by irradiating the optical disk with the laser beam are clockwise or counterclockwise with respect to the optical axes of the laser beam and the reflected light. Each optical rotation unit emits light by a predetermined amount in each direction and has at least two optical rotation units, and an objective lens that converges the laser beam from the optical rotation unit and irradiates the optical disc. Also, elastic supporting means for elastically supporting the objective lens so as to be movable in all directions, light receiving means for receiving the reflected light from the polarization beam splitter, and outputting a light receiving signal according to the amount of light, The tilt of the optical disc is detected based on the light receiving signal from the light receiving unit, and the elastic supporting unit is provided so that the laser beam is irradiated to the optical disc at a predetermined angle according to the detected tilt of the optical disc. And drive control means.

Specifically, as the optical rotation means, the first and third optical means rotate the incident light by a predetermined amount in the clockwise direction and emit it.
Of the laser beam and the reflected light are divided into four equal parts radially around the optical axis of the laser beam and the reflected light. The first to fourth incident areas are provided so that adjacent incident areas have different optical rotation characteristics.

On the other hand, as the light receiving means, a light receiving area for receiving the reflected light from the polarization beam splitter is radially divided into four equal parts about the optical axis. Then, by supporting the objective lens at two points by the elastic supporting means, the objective lens can be moved in all directions.

Alternatively, the objective lens is composed of a pair of drive coils provided at mutually opposite positions and having two coils inside, and two magnets provided close to the drive coils. Provided in the movable unit,
By supporting the movable unit at two points with two elastic arms, the movable unit can be moved in all directions. Optical rotation means may be provided in the movable unit together with the objective lens.

Alternatively, the movable unit may be provided with the laser light source, the polarization beam splitter and the light receiving means together with the objective lens. Next, as the optical rotation means, the first incident area and the incident light, which are rotated by a predetermined amount in the clockwise direction and are emitted with the optical axis of the laser beam and the reflected light as boundaries, are emitted in the counterclockwise direction. It is also possible to provide a second incident area that is rotated and emitted in a predetermined amount and is divided into two equal parts.

At this time, as the light receiving means, one having light receiving regions arranged in parallel so as to receive the reflected light from the polarization beam splitter by dividing into four is provided. Then, by supporting the objective lens at two points by the elastic supporting means, the objective lens can be moved in all directions.
Alternatively, in a movable unit that includes the pair of drive coils having the objective lenses provided at positions facing each other and having two coils inside, and two magnets provided close to the drive coils. The movable unit is supported by two elastic arms at two points,
It can be moved in any direction.

The movable unit may be provided with the optical rotation means together with the objective lens. Alternatively, in the movable unit, together with the objective lens,
The laser light source, the polarization beam splitter, and the light receiving means may be provided.

[0026]

The optical pickup device according to the present invention irradiates the optical disc with the laser beam emitted from the laser light source through the polarization beam splitter, the optical rotation means and the objective lens. Specifically, the optical rotation means rotates the incident light by a predetermined amount in the clockwise direction and emits it, and outputs the first and third incident regions and the second incident light by rotating the incident light in the counterclockwise direction by a predetermined amount. , The fourth incident area is radially divided into four equal parts about the optical axes of the laser beam and the reflected light, and
The fourth incident regions are arranged so that adjacent incident regions have different optical rotation characteristics.

Therefore, although the laser beam incident on the optical rotation means is apparently one laser beam, it is divided into four equal parts about the optical axis, and each laser beam is rotated in different optical rotation directions. Then, the optical disc is irradiated. When the optical disk is irradiated with the laser beam in this manner, reflected light is generated. This reflected light is supplied to the optical rotation means via the objective lens, but since the traveling direction is different between the laser beam and the reflected light, the forward path and the backward path are reversed, and the clockwise optical rotation direction is set at the laser beam stage. The light that has entered the incident area has the incident area that has a counterclockwise optical rotation direction at the stage of reflected light.

Therefore, the light that has been rotated by a predetermined amount in the clockwise direction at the stage of the laser beam is further rotated by a predetermined amount in the clockwise direction at the stage of the reflected light, and conversely, in the counterclockwise direction at the stage of the laser beam. The light that has been rotated by a predetermined amount is further rotated by a predetermined amount in the counterclockwise direction at the stage of reflected light, and is emitted from the optical rotation means. Therefore, the reflected light is
For example, it has both a first polarization component and a second polarization component which is a polarization component orthogonal to the first polarization component, and is irradiated onto the light receiving means via the polarization beam splitter.

In the light receiving means, the light receiving area for receiving the reflected light from the polarization beam splitter is radially divided into four equal parts with the optical axis as the center, and the amount of the reflected light received by each light receiving area is divided into four equal parts. The respective received light signals are formed and supplied to the control means. The control means detects the tilt of the optical disc based on the light receiving signal from the light receiving means. Specifically, by vertically irradiating the optical disk with a laser beam, the laser beam and the reflected light have the same optical path, and the laser beam is incident on an incident area having a clockwise optical rotation direction at the laser beam stage. Light is incident on an incident area having a counterclockwise optical rotation direction at the stage of reflected light. However, if the optical disc is tilted and the laser beam is not vertically irradiated, the laser beam is changed according to the tilt of the optical disc. Light incident on the incident region having the clockwise rotation direction at the beam stage is again incident on the incident region having the clockwise rotation direction at the reflected light stage, or counterclockwise at the laser beam stage. The light incident on the incident area having the optical rotation direction in the clockwise direction is again incident on the incident area having the optical rotation direction in the counterclockwise direction at the stage of the reflected light.

When such a situation occurs, the laser beam rotated clockwise or counterclockwise in the stage of the laser beam is returned and rotated by the amount rotated in the stage of the reflected light. . Then, when the light receiving means is provided so as to receive the reflected light reflected by the polarization beam splitter, by being returned and rotated by the amount of the light rotated at the stage of the reflected light, the original polarization beam splitter Since the reflected light that should be reflected passes through the polarization beam splitter, a portion (dark line) where the reflected light is not emitted occurs in the light receiving area of the light receiving means depending on the tilt of the optical disc. Alternatively, when the light receiving means is provided so as to receive the reflected light that has passed through the polarization beam splitter, the light is originally reflected by the polarization beam splitter by being rotated and rotated by the amount of the light rotated at the stage of the reflected light. Since the reflected light that is supposed to be transmitted passes through the polarization beam splitter, a portion (bright line) having a large amount of reflected light is generated in the light receiving area of the light receiving means according to the inclination of the optical disc.

The control means detects the tilt of the optical disc by detecting the dark line or the bright line based on the light receiving signals from the respective light receiving regions of the light receiving means, and in accordance with the detected tilt of the optical disc. The elastic support means that supports the objective lens is driven and controlled so that the laser beam is vertically irradiated to the optical disk. The elastic supporting means supports the objective lens at two points by elastic supporting means such as a wire, a leaf spring or a spring so that the objective lens can be moved in any direction.

For this reason, the laser beam can always be vertically irradiated by following any inclination of the optical disc, and coma aberration caused by the inclination of the optical disc can be prevented. Further, the light receiving means can be used also as a detection system for tracking error, focus error, etc., and since only the objective lens is moved, the cost can be reduced by simplifying the structure and downsizing the optical pickup device itself. Can be planned.

Further, since the coma aberration can be electrically corrected by the light receiving means and the control means, it is possible to perform the correction in substantially real time. It is possible to prevent such an inconvenience. Further, since the tilt of the disc is detected based on the reflected light, the amount of tilt currently occurring between the laser beam and the optical disc can be accurately detected, and the coma aberration can be accurately corrected. It can be performed.

Next, the objective lens is composed of a pair of drive coils provided at mutually opposite positions and having two coils inside, and two magnets provided close to the drive coils. The movable unit may be provided in the movable unit, and the movable unit may be supported by two elastic arms at two points so as to be movable in all directions, and the drive may be controlled according to the inclination of the optical disc.

Further, optical rotation means may be provided in the movable unit together with the objective lens, or the laser light source, polarization beam splitter and light receiving means may be provided in the movable unit together with the objective lens. As a result, the optical pickup device can be further downsized, and it can greatly contribute to the cost reduction of the optical disc recording device, the optical disc reproducing device, the optical disc recording / reproducing device and the like provided with the optical pickup device.

Next, as the optical rotation means, the first incident area and the incident light, which are rotated by a predetermined amount in the clockwise direction and are emitted with the optical axes of the laser beam and the reflected light as boundaries, are rotated counterclockwise. A second incident area that is rotated and output in a predetermined direction is provided with a two-divided area, and as the light receiving means, the reflected light that has passed through the polarization beam splitter is divided into four and received. It is also possible to provide one having each of the light receiving regions arranged side by side.

In this case, when the optical disk is tilted, the laser beam rotated clockwise by a predetermined amount in the first incident area of the optical rotating means is again reflected at the stage of reflected light according to the tilt of the optical disk. The light is incident on the first incident region, and is rotated in the clockwise direction at the stage of the laser beam, and is returned and rotated at the stage of reflected light. Also,
The laser beam, which is rotated by a predetermined amount in the counterclockwise direction in the second incident region of the optical rotation means, is again reflected in the second incident region at the stage of reflected light.
Is incident on the incident area of the laser beam, and is rotated in the counterclockwise direction at the stage of the laser beam, and is returned and rotated at the stage of the reflected light.

Therefore, when the light receiving means is provided so as to receive the reflected light reflected by the polarization beam splitter, the laser beam originally supposed to be reflected by the polarization beam splitter passes through the polarization beam splitter. Therefore, a dark line will be generated in any of the light receiving regions of the above-mentioned light receiving means. Alternatively, when the light receiving means is provided so as to receive the reflected light transmitted through the polarization beam splitter, the laser beam originally supposed to be reflected by the polarization beam splitter passes through the polarization beam splitter, A bright line will be generated in any of the light receiving regions of the light receiving means.

Therefore, the control means can detect the inclination of the optical disk by detecting the dark line or the bright line, and drives the elastic supporting means according to the inclination of the optical disk. The elastic support means is configured to move the objective lens in all directions, such as a wire or a leaf spring,
It is supported at two points by elastic supporting means such as springs.

For this reason, the laser beam can always be vertically irradiated in accordance with any inclination of the optical disc, and coma aberration caused by the inclination of the optical disc can be prevented. Further, the light receiving means can be used also as a detection system for tracking error, focus error, etc., and since only the objective lens is moved, the cost can be reduced by simplifying the structure and downsizing the optical pickup device itself. Can be planned.

Further, since the coma aberration can be electrically corrected by the light receiving means and the control means, it is possible to perform the correction in substantially real time, and the coma aberration is increased by delaying the correction. It is possible to prevent such an inconvenience. Further, since the tilt of the disc is detected based on the reflected light, the amount of tilt currently occurring between the laser beam and the optical disc can be accurately detected, and the coma aberration can be accurately corrected. It can be performed.

Next, the objective lens is composed of a pair of drive coils provided at positions facing each other and having two coils inside, and two magnets provided close to the drive coils. The movable unit may be provided in the movable unit, and the movable unit may be supported by two elastic arms at two points so as to be movable in all directions, and the drive may be controlled according to the inclination of the optical disc.

Further, optical rotation means may be provided in the movable unit together with the objective lens, or the laser light source, polarization beam splitter and light receiving means may be provided in the movable unit together with the objective lens. As a result, the optical pickup device can be further downsized, and it can greatly contribute to the cost reduction of the optical disc recording device, the optical disc reproducing device, the optical disc recording / reproducing device and the like provided with the optical pickup device.

[0044]

Embodiments of the optical pickup device according to the present invention will be described below with reference to the drawings. The optical pickup device according to the present invention can be applied as an optical system of a magneto-optical disc reproducing device for reproducing recorded data from the magneto-optical disc 1 as shown in FIG. 1, for example.

The optical pickup device according to the first embodiment includes a collimator lens 3 and a beam between a magneto-optical disc 1 and a laser light source 2 which emits a laser beam for irradiating the magneto-optical disc 1. Splitter 4, polarization beam splitter 5, 4-split optical plate 7 and movable unit 6
, Are provided in order with the optical axis of the laser beam as the center.

The beam splitter 4 has a polarizing beam splitter film 4a which has a characteristic of reflecting incident light by a predetermined amount and transmitting it by a predetermined amount. The polarization beam splitter 5 has a characteristic of transmitting light of so-called P-polarized component and reflecting light of S-polarized component having a polarization component in a polarization direction orthogonal to the P-polarized component. 5a.

A first photodetector 10 is provided at a location irradiated with the reflected light reflected by the polarization beam splitter 5, and a magneto-optical signal (MO signal) is detected based on the received reflected light. It is supposed to do. In addition, the second photodetector 1 is provided at a portion irradiated with the reflected light reflected by the beam splitter 5.
5, the skew detection circuit 12 detects the tilt of the magneto-optical disk 1 as well as the tracking error signal and the focus error signal based on the received reflected light. Then, according to the inclination of the magneto-optical disk 1 detected by the skew detection circuit 12,
The skew control circuit 17 is adapted to correct the inclination of the movable unit 6.

The movable unit 6 has a substantially rectangular shape as shown in FIG. 2, and a normal objective lens 8 is provided at the center thereof. In addition, the elastic arm fixing portions 6 are arranged so as to face each other at approximately the middle position of each longitudinal side.
a and 6b are provided. This elastic arm fixing part 6
One end of an elastic arm 9 formed of an elastic member such as rubber, leaf spring, spring, or wire is fixed to a and 6b, and the other ends of the two elastic arms 9 are fixed to the fixed wall 30. Each is fixed. In addition, the movable unit 6
Inside of the, along each short side, two each,
A total of four drive coils 31 to 34 are provided, and magnets 35 and 36 are provided close to the drive coils 31 and 32 and drive coils 33 and 34, respectively.

Therefore, the movable unit 6 is supported at two points by the elastic arm 9 and each of the drive coils 31 to 31.
It is movable in all directions based on the current supplied to 34 and the magnetic field generated by the magnets 35 and 36. As shown in FIG. 4, the four-divided optical rotation plate 7 has its entire incident area radially divided into four equal areas 7L1, 7R1, 7L2, 7R2 about the optical axis of the laser beam. The incident region 7L1 has a characteristic that the incident light is rotated by, for example, 22.5 degrees to the left and emitted, and the incident region 7R1 rotates the incident light by, for example, 22.5 degrees to the right. The incident area 7L2 has a characteristic that the incident light is rotated by 22.5 degrees to the left and emitted, and the incident area 7R2 has a characteristic that the incident light is emitted by, for example, 22. It has a characteristic of rotating and emitting light to the right by 5 degrees. Therefore, the laser beam and the reflected light that are incident on the four-division optical rotation plate 7 are emitted by being rotated by 22.5 degrees in the optical rotation directions corresponding to the respective incident areas 7L1, 7R1, 7L2, and 7R2. .

Next, the operation of the optical pickup device according to this embodiment having the above structure will be described. First, in FIG. 1 described above, FIG.
The P-polarized component laser beam as shown in (1) is collimated by the collimator lens 3 and is incident on the beam splitter 4. The beam splitter 4 transmits the incident laser beam by a predetermined amount and reflects it by a predetermined amount by the beam splitter film 4a. The laser beam transmitted through the beam splitter 4 is incident on the polarization beam splitter 5, and the laser beam reflected by the beam splitter 4 is received by the light amount detection system to keep the emitted light amount of the laser light source 2 constant. Used.

The polarization beam splitter film 5a of the polarization beam splitter 5 has a characteristic of transmitting the light of P polarization component and reflecting the light of S polarization component. Therefore, the laser beam incident on the polarization beam splitter 5 via the beam splitter 4 passes through the polarization beam splitter 5 and is incident on the four-division optical rotation plate 7. In FIG. 4, the four-division optical rotation plate 7 rotatably radiates the laser beam by 22.5 degrees to the right as shown in FIG. 3B by the incident area 7R1 and emits the laser beam by the incident area 7L1. 22. to the left as shown in FIG.
It is rotated 5 degrees and emitted. Further, the four-division optical rotation plate 7 is
The incident region 7R2 causes the laser beam to move to the position shown in FIG.
As shown in (b), the light is rotated by 22.5 degrees to the right and emitted, and the incident region 7L2 outputs the laser beam by rotating it by 22.5 degrees in the left as shown in (c).

This laser beam is focused by the objective lens 8 provided on the movable unit 6 and irradiated on the magneto-optical disk 1. Next, the magneto-optical disk 1 is irradiated with the laser beam to generate reflected light. The reflected light is again incident on the four-divided optical rotation plate 7 via the objective lens 8 of the movable unit 6. At this time, since the traveling directions of the laser beam and the reflected light are different, the light passing through the incident region 7L1 at the stage of the laser beam is
The incident light is incident on the incident region 7R2 at the stage of reflected light, and the light passing through the incident region 7R2 at the stage of the laser beam is incident on the incident region 7L1 at the stage of reflected light. Further, the light passing through the incident region 7L2 at the laser beam stage is incident on the incident region 7R1 at the reflected light stage, and the light passing through the incident region 7R1 at the laser beam stage is incident at the reflected light stage. It is incident on the region 7L2.

As a result, the reflected light incident on the incident area 7L1 is further rotated by 22.5 degrees rightward and emitted, and the reflected light incident on the incident area 7R1 is
The light is further rotated by 22.5 degrees to the left and emitted. The reflected light incident on the incident area 7L2 is further rotated by 22.5 degrees to the right and emitted, and the reflected light incident on the incident area 7R2 is further rotated by 22.5 degrees to the left. It is rotated and emitted.

The reflected light is rotatively reflected by θk by the so-called Kerr effect according to the recording data recorded on the magneto-optical disk 1. Therefore, the reflected light passing through each of the incident areas 7L1, 7R1, 7L2, 7R2 is rotated by ± 45 ° + θk in the right direction or the left direction as shown in FIGS. The component and the S-polarized component are emitted so as to have them. The reflected light is incident on the polarization beam splitter 5.

As described above, the polarization beam splitter film 5a of the polarization beam splitter 5 has a characteristic of transmitting the P-polarized component light and reflecting the S-polarized component light. Therefore, of the reflected light that has entered the polarization beam splitter 5, the reflected light of the S-polarized component as shown in FIGS. 3F and 3G is reflected by the polarization beam splitter film 5a and is reflected by the first photodetector. The reflected light of the P-polarized component is emitted to the beam splitter 10, passes through the polarization beam splitter film 5a, and enters the beam splitter 4.

The polarization beam splitter 4 reflects the reflected light of the P-polarized component by a predetermined amount, and reflects it by the objective lens 14.
The second photodetector 15 is irradiated with the light. As shown in FIG. 5A, the first photodetector 10 has first to fourth light receiving regions 10 each having a rectangular light receiving region.
It is divided into four equal parts, A to 10D. The light receiving areas 10A to 10D are arranged in parallel.

In the first photodetector 10 as described above, when the reflected light is accurately received (normal), as shown in FIG. 5 (a), the reflected light is approximately at the center of the light receiving area. Receive light. Then, each of the light receiving regions 10A to 10
A light reception signal corresponding to the amount of reflected light received at D is formed and output. The light receiving signal from the first light receiving area 10A is supplied to the adder 18 and the adder 20, the light receiving signal from the second light receiving area 10B is supplied to the level adjusting circuit 22, and the third light receiving area 10C is supplied. The received light signal is supplied to the level adjustment circuit 23, and the received light signal from the fourth light receiving region 10D is supplied to the adder 19 and the adder 21.

As shown in FIG. 5B, the light amount of the reflected light has a peak at the central portion and gradually decreases from the central portion to the peripheral portion. For this reason,
The level of the light receiving signal from the first light receiving area 10A in the normal state is, for example, about 1/2 of the level of the light receiving signal from the second light receiving area 10B, and the fourth light receiving signal is generated.
The level of the light receiving signal from the light receiving area 10D is about 1/2 of that of the light receiving signal from the third light receiving area 10C.

Therefore, the level adjusting circuit 22 reduces the level of the light receiving signal from the second light receiving region 10B to 1 /.
By attenuating to 2, the levels of the light receiving signals from the first and second light receiving regions 10A and 10B are adjusted to the same level. Then, the level-adjusted light reception signal from the second light receiving region 10B is supplied to the adder 19 and the adder 20.

Further, the level adjusting circuit 23 attenuates the level of the light receiving signal from the third light receiving area 10C to ½ to thereby reduce the level of the third and fourth light receiving areas 10.
The levels of the light receiving signals from C and 10D are adjusted to be the same level. Then, the level-adjusted received light signal from the third light receiving region 10C is added to the adder 1
8 and the adder 21.

In the level adjusting circuits 22 and 23, instead of attenuating the levels of the light receiving signals from the second and third light receiving regions 10B and 10C, level adjustment is performed to double the level of the light receiving signals. Circuits may be provided on the output side of the first light receiving area 10A and the output side of the fourth light receiving area 10D, and adjustment may be performed so that the levels of the light receiving signals from the respective light receiving areas 10A to 10D are the same level. .

The adder 20 includes the first light receiving area 1
The light receiving signal from 0A and the light receiving signal from the second light receiving region 10B whose level has been adjusted by the level adjusting circuit 22 are added, and the added signal is supplied to the non-inverting input terminal 25a of the MO signal detecting circuit 25. Also, the adder 21
Adds the received light signal from the fourth light receiving region 10D and the received light signal from the third light receiving region 10C whose level has been adjusted by the level adjusting circuit 23, and adds the addition signal to the MO signal detecting circuit 25. It is supplied to the inverting input terminal 25b. In the first photodetector 10, the boundary between the second and third light receiving regions 10B and 10C is the incident regions 7L1, 7R2 and 7R1, 7L of the four-division optical rotation plate 7.
It is provided so as to coincide with each boundary of 2. Therefore, in the MO signal detection circuit 25, the sum signal of the light receiving signals from the first and second light receiving regions 10A and 10B and the light receiving signals from the third and fourth light receiving regions 10C and 10D are obtained. The MO signal recorded on the magneto-optical disc 1 can be obtained by subtracting the addition signal of the above.

The MO signal from the MO signal detection circuit 25 is supplied to the subtraction circuit 13 and the output terminal 26.
Is supplied to, for example, a signal processing circuit or the like (not shown). Here, as shown in FIG.
However, for example, when it is tilted by θ in the lower right direction in the figure, the laser beam is not vertically irradiated to the magneto-optical disk 1, and a deviation occurs between the optical axis of the laser beam and the optical axis of the reflected light. Then, for example, the laser beam that has passed through the incident region 7L1 of the four-division optical rotation plate 7 at the laser beam stage is re-incident on the incident region 7L1 at the reflected light stage, and leftward by 22.5 degrees at the laser beam stage. The part of the reflected light has only the P-polarized component like the laser beam.

As described above, the polarization beam splitter film 5a of the polarization beam splitter 5 has the characteristic of transmitting the light of the P-polarized component and reflecting the light of the S-polarized component. When it occurs, the above-mentioned part of the reflected light, which is supposed to be reflected, passes through the polarization beam splitter 5. When a part of the reflected light passes through the polarization beam splitter 5 as described above, the beam spot of the reflected light irradiated on the first photodetector 10 is changed to the magneto-optical disk as shown in FIG. 7A. 1 is irradiated in a direction opposite to the tilted direction, and a part of the reflected light is transmitted through the polarization beam splitter 5, so that as shown by diagonal lines in FIGS. For example, the light amount of the reflected light with which the second light receiving region 10B of the first photodetector 10 is irradiated is reduced.

Similarly, as shown in FIG. 8, when the magneto-optical disk 1 is tilted, for example, by θ in the lower left direction in the figure, the laser beam is not vertically irradiated to the magneto-optical disk 1,
A deviation occurs between the optical axis of the laser beam and the optical axis of the reflected light. Then, for example, the laser beam that has passed through the incident region 7R2 of the four-division optical rotation plate 7 at the stage of the laser beam is made incident again on the incident region 7R2 at the stage of the reflected light, and is moved to the right by 22.5 degrees at the stage of the laser beam. The part of the reflected light has only the P-polarized component like the laser beam.

As a result, the original polarization beam splitter 5
The above-mentioned part of the reflected light that should be reflected by will be transmitted through the polarization beam splitter 5. When a part of the reflected light passes through the polarization beam splitter 5 as described above, the beam spot of the reflected light irradiated on the first photodetector 10 is changed to the magneto-optical disk as shown in FIG. 9A. 1 is irradiated in a direction opposite to the tilted direction, and a part of the reflected light is transmitted through the polarization beam splitter 5, so that as shown by diagonal lines in FIGS. For example, the light amount of the reflected light with which the third light receiving region 10C of the first photodetector 10 is irradiated is reduced.

From the above, the adder 18 is
The light receiving signal from the first light receiving area 10A and the light receiving signal from the third light receiving area 10C whose level has been adjusted by the level adjusting circuit 23 are subjected to addition processing, and this addition signal is added to the first difference detection circuit 24. To the non-inverting input terminal 24a. Further, the adder 19 is provided with the fourth light receiving area 1
The light receiving signal from 0D and the light receiving signal from the second light receiving region 10B whose level has been adjusted by the level adjusting circuit 22 are added, and the added signal is inverted by the inverting input terminal 24b of the first difference detecting circuit 24. Supply to.

The first difference detection circuit 24 performs the addition processing of the addition signal from the adder 18 and the addition signal from the adder 19 to remove the MO signal component from the tilt of the magneto-optical disk 1. Minute, that is, the offset amount is detected. Then, the subtraction circuit 1 to which the MO signal is supplied from the offset signal through the low-pass filter 11
Supply 3

The subtraction circuit 13 subtracts the offset signal from the MO signal to form an accurate MO signal from which the offset component caused by the inclination of the magneto-optical disk 1 is removed, and this is output terminal 16 And is supplied to the signal processing circuit and the like via. In the signal processing circuit and the like, the MO signal output via the output terminal 26 and having the offset component superimposed thereon and the output terminal 1
Which of the MO signals from which the offset has been removed and which is output via 6 is to be used may be appropriately selected according to the system.

On the other hand, of the reflected light incident on the polarization beam splitter 5, the reflected light of the P-polarized component and the magneto-optical disk 1 are tilted, so that they are originally reflected by the polarization beam splitter 5. The reflected light, which should be reflected, enters the beam splitter 4 shown in FIG. The beam splitter 4 includes the beam splitter film 4
The reflected light is reflected by a predetermined amount by a and transmitted by a predetermined amount.
Of these, the reflected light reflected by the beam splitter film 4 a is applied to the second photodetector 15 via the objective lens 14.

The second photodetector 15 shown in FIG.
As shown in 0 (a), when the magneto-optical disk 1 is not tilted, the reflected light is received so that the optical axis of the reflected light becomes the center of the second photodetector 15. The light receiving region is radially divided into four equal parts with the optical axis as the center. When the magneto-optical disk 1 is not tilted, the second photodetector reflects the reflected light that should be reflected by the polarization beam splitter 5, so that four received light beams are received as shown in FIG. The areas E to H are uniformly irradiated with the reflected light.

However, when the magneto-optical disk 1 is tilted to the right of the track direction of the magneto-optical disk 1 (+ tangential direction), each of the light receiving areas E to H is irradiated as shown in FIG. 10B. The reflected light is radiated toward the light receiving regions E and F, and a part of the reflected light transmitted through the polarization beam splitter 5 (reflected light that should originally be reflected by the polarization beam splitter 5) is radiated. As indicated by the diagonal lines in FIG. 6B, a portion (bright line) having a large amount of received light occurs near the light receiving regions E and F.

On the contrary, when the magneto-optical disk 1 is tilted to the left (-tangential direction) in the track direction of the magneto-optical disk 1, as shown in FIG. The reflected light applied to the
As a part of the reflected light is irradiated while the light is irradiated to the side, bright lines are generated near the light receiving regions G and H as indicated by the diagonal lines in FIG.

When the magneto-optical disk 1 is tilted in the radial inner direction (+ radial direction) of the magneto-optical disk 1,
As shown in FIG. 10 (d), the reflected light emitted to each of the light receiving regions E to H is emitted toward the light receiving regions E and G, and the part of the reflected light is emitted. Figure (d)
As indicated by the middle shaded line, a bright line is generated near the light receiving regions E and G.

On the contrary, the magneto-optical disk 1 is moved in the radial direction of the magneto-optical disk 1 (-radial direction).
When the light beam tilts, as shown in FIG.
The reflected light radiated to H is radiated toward the light receiving regions F and H, and a part of the reflected light is radiated.
As indicated by the slanted lines in FIG. 8E, bright lines are generated near the light receiving regions F and H.

When the magneto-optical disk 1 is tilted in the −tangential direction and the −radial direction of the magneto-optical disk 1, the reflected light emitted to each of the light receiving areas E to H as shown in FIG. The light is irradiated toward the side of the light receiving region H and the part of the reflected light is also irradiated.
As indicated by the diagonally shaded lines, bright lines occur near the light receiving regions E, F, and G.

The second photodetector 15 forms the light amount detection signals corresponding to the received light amounts of the respective light receiving regions E to H generated according to the inclination of the magneto-optical disk 1 in this way, and these are detected. Supply to. The skew detecting circuit 12 sets the light receiving signals from the respective light receiving regions E to H as E to H, and calculates the tilt of the magneto-optical disk 1 in the tangential direction and the tilt of the magneto-optical disk 1 in the radial direction by the following equation 1 And the equation 2 is calculated and detected.

Tangential skew = (E + F) − (G + H) ... Equation 1 Radial skew = (E + G) − (F + H) ... Equation 2 Then, the skew detection circuit uses the signal that detects this inclination as a skew detection signal. Supply to 17. The skew control circuit 17 supplies a skew control signal to the four drive coils 31 to 34 shown in FIG. 2 according to the inclination of the magneto-optical disk 1 detected by the skew detection circuit 12.

As a result, the movable unit 6 can be controlled to move according to the magnetic fields generated by the magnets 35 and 36 and the skew control signals supplied to the four drive coils 31 to 34. At this time, the movable unit 6
Is supported at two points by the two elastic arms 9 as described above, and in accordance with the tilt of the magneto-optical disk 1,
Since the drive coils 31 to 34 are separately driven by supplying the skew control signals, the movement of the movable unit 6 can be controlled in all directions.

Therefore, it is possible to follow all the tilts of the magneto-optical disk 1, and it is possible to prevent coma from occurring by always irradiating the magneto-optical disk 1 with the laser beam perpendicularly. Further, since such coma aberration can be corrected by controlling the movement of only the objective lens 8, it is possible to simplify the configuration and downsize the optical pickup device itself, thereby reducing the cost. Can be achieved.

Further, the second photo detector 15,
Since the coma aberration can be electrically corrected by the skew detection circuit 12 and the skew control circuit 17, the correction can be performed substantially in real time, and the coma aberration is increased due to the delay of the correction. Such inconvenience can be prevented. Further, since the tilt of the disk is detected based on the reflected light of the laser beam, the tilt amount generated between the laser beam and the magneto-optical disk 1 can be accurately detected at the present time. It is possible to correct various coma aberrations.

The inclination of the magneto-optical disk 1 is set to the second
The photodetector 15 detects the tilt, but since the optical pickup device can efficiently use the reflected light, the tilt can be accurately detected. Further, it is possible to use the above skew detection signal at the time of alignment to enable automatic assembly according to the skew adjustment of the objective lens.

The focus error and the tracking error are calculated by the so-called astigmatism method and push-pull method using the respective received light signals E to H of the second photodetector 15 as shown in the following expressions 3 and 4. It is detected based on. Focus error = (E + G)-(F + H) ... Equation 3 Tracking error = (E + H)-(F + G) ... Equation 4 The focus error signal and the tracking error signal are the drive coils 31 to 31 of the movable unit 6. 34. As a result, the movable unit 6 is moved in the direction in which the focus error and the tracking error are corrected, and the recording or the reproduction can always be performed with the just focus and the just track.

In the optical pickup device, the second photodetector 15 can be shared as a tracking error / focus error detection system and a tilt detection system for the magneto-optical disk 1, so that the number of parts can be further reduced. Also, the cost can be reduced by simplifying the configuration. Next, an optical pickup device according to the second embodiment of the present invention will be described. In the description of the optical pickup device according to the second embodiment, the same reference numerals are given to the portions showing the same operations as those of the optical pickup device according to the first embodiment, and detailed description thereof will be omitted.

That is, the optical pickup device according to the first embodiment described above controls the movement of only the objective lens 8 in accordance with the inclination of the magneto-optical disk 1.
As shown in FIG. 11, the optical pickup device according to the embodiment is provided with the objective lens 8 and the four-divided optical rotation plate 7 with the optical axes aligned with each other in the movable unit 6 as shown in FIG.

This makes it possible to obtain the same effects as the optical pickup device according to the first embodiment described above, and
Since the 4-division optical rotation plate 7 can be controlled to move together with the objective lens 8 according to the inclination of the magneto-optical disk 1, the coma aberration does not shift the optical axis of the objective lens 8 and the 4-division optical rotation plate 7. Can be corrected. Next, an optical pickup device according to the third embodiment of the present invention will be described.

As shown in FIG. 12, the optical pickup device according to the third embodiment has a movable unit 40 in which a laser light source 41, a first reflection mirror 42, and polarization beam splitters 43, 4 are provided. Split optical rotation plate 4
The fourth reflection mirror 45 and the objective lens 46 are provided. The movable unit 40 has a substantially rectangular shape as shown in FIG. 13, and the normal objective lens 8 and the photodetector 4 extend from the upper position to the lower position.
8 and a laser light source 41 are provided in that order. Further, elastic arm fixing portions 40a and 40b are provided so as to face each other at approximately intermediate positions of the respective long sides. The elastic arm fixing portions 40a and 40b include
For example, one end of an elastic arm 49 formed of an elastic member such as rubber, leaf spring, spring, wire is fixed,
The other ends of the two elastic arms 49 are fixed to the fixed wall 50, respectively. Further, inside the movable unit 40, two driving coils 53 to 56 are provided, two each in total along each short side, and the driving coils 53 and 54 and the driving coils 55 and 56 are provided in the driving coils 53 and 54. Magnets 51 and 52 are provided close to each other.

Therefore, the movable unit 40 is supported at two points by the elastic arm 49, and each of the drive coils 5 is
It is possible to move in all directions based on the current supplied to 3-56 and the magnetic field generated by the magnets 51 and 52. The 4-division optical rotation plate 44 is the 4-division optical rotation plate 7 described above.
Similarly to the above, the photodetector 48 is a photodetector having four light receiving regions which are divided into four and are arranged in the same manner as the first photodetector 10 described above. The polarization beam splitter film 43a of the polarization beam splitter 43 is
It has a characteristic of transmitting the light of the P-polarized component and reflecting the light of the S-polarized component.

Next, the operation of the optical pickup device according to the third embodiment having such a configuration will be described. First,
In FIG. 12, approximately P emitted from the laser light source 41
The laser beam of the polarization component is reflected by the first reflection mirror 42, enters the polarization beam splitter 43, and enters the four-part optical rotation plate 44 via the polarization beam splitter film 43a. The four-division optical rotation plate 44, like the four-division optical rotation plate 7, rotates the laser beam incident on each of the incident areas by 22.5 degrees in the right direction or the left direction by each of the four incident areas. The magneto-optical disk 47 is irradiated with light through the second reflecting mirror 45 and the objective lens 46.

Next, the magneto-optical disk 47 is irradiated with a laser beam to generate reflected light. This reflected light is made incident on the four-division optical rotation plate 44 via the objective lens 46 and the second reflection mirror 45, and the P polarization component and S
It is incident on the polarization beam splitter 43 as reflected light having both polarization components of the polarization component. Since the polarization beam splitter film 43a of the polarization beam splitter 43 has the characteristic of transmitting the P-polarized component and reflecting the S-polarized component as described above, the reflected light of the S-polarized component of the reflected light is polarized. The light is reflected by the beam splitter film 43a and irradiated on the photodetector 48.

Like the first photodetector 10, the photodetector 48 detects the light amount of the reflected light received by the four light receiving regions and supplies the light amount detection signal to the skew detecting circuit 12. As described with reference to FIGS. 6 to 9, when the magneto-optical disk 47 is tilted, a dark line is generated in each light receiving area. Therefore, the skew detecting circuit 12 detects the tilt of the magneto-optical disk 47 based on the light receiving signals from the respective light receiving areas, and supplies the skew detecting signal to the skew control circuit 17. The skew control circuit 17 responds to the skew detection signal by each drive coil 53 of the movable unit 40.
~ 56 to the skew control signal.

As a result, the movable unit 40 can be moved by following the inclination of the magneto-optical disk 47 to prevent the occurrence of coma aberration, and at the same time, the above-mentioned first
It is possible to obtain the same effect as the optical pickup device according to the embodiment. Furthermore, in the optical pickup device according to the third embodiment, the laser light source 41, the polarization beam splitter 43, the four-division optical rotation plate 44, and the objective lens 46 are used.
Since it can be integrally provided in the movable unit 40, the optical pickup device itself can be further downsized, and the cost can be reduced by simplifying the configuration and the like.

In the above description of the first embodiment, the second photodetector 15 is provided in addition to the first photodetector 10 described above, and the inclination of the magneto-optical disk 1 is indicated by the bright line in the second photodetector 15. It was decided to detect, but this is the second photodetector 15 mentioned above.
Alternatively, the inclination detection may be performed by the dark line in the first photodetector 10 by omitting. in this case,
The beam splitter 4 that separates the reflected light from the polarization beam splitter 5 can be omitted, and the size and cost can be further reduced.

Further, in the above description of each embodiment, the light receiving regions of the first photodetector 10 and the photodetector 48 are equally divided into four, and the light receiving signals from the respective light receiving regions E to H are used by using the level adjusting circuits 22 and 23. The levels of the first and second levels are adjusted to the same level. This is as shown in FIG.
A photodetector 60 having a divided light receiving area is provided so that the light receiving amounts of the second light receiving regions 60A and 60B are equal and the light receiving amounts of the third and fourth light receiving regions 60C and 60D are equal. The received light signal level may be adjusted. In this case, the level adjusting circuit 2
2, 23 can be omitted, and the cost can be further reduced by reducing the number of parts.

Further, in the above description of each embodiment, the first photodetector 1 having the four light receiving regions E to H is provided.
Although 0 and 48 are provided, as shown in FIG. 15, two light receiving regions 70 arranged in parallel in one direction are provided.
You may make it provide the photodetector 70 which has A and 70B in the center part. In this case, since the two light receiving areas 70A and 70B are arranged in parallel in the central portion in one direction, the received light amount can be at the same level, and the light receiving signals from the respective light receiving areas 70A and 70B can be directly input to the above. The offset signal can be obtained by supplying it to the first difference detection circuit 24. Therefore, the level adjusting circuits 22 and 23 can be omitted, and the cost can be further reduced by reducing the number of parts.

Finally, in the above description of each embodiment, the optical pickup device according to the present invention is applied to the magneto-optical disk reproducing device. However, from the technical idea of the present invention, the present invention will be described. It is needless to say that the present invention can be applied not only to a magneto-optical disc but also to a recording device, a reproducing device and a recording / reproducing device of any optical disc such as a compact disc and a video disc.

[0097]

The optical pickup device according to the present invention can always irradiate the laser beam vertically by following any inclination of the optical disc, and can prevent the occurrence of coma aberration caused by the inclination of the optical disc. Further, since the tilt of the optical disc can be detected based on the light receiving signal of the light receiving means provided as a detection system for tracking error, focus error, etc., the objective lens alone or the movable unit is moved. The cost can be reduced through simplification of the above and miniaturization of the optical pickup device itself.

Further, since the coma aberration can be electrically corrected by the light receiving means and the control means, it is possible to perform the correction in substantially real time, and the coma aberration is delayed and the coma aberration is increased. It is possible to prevent such an inconvenience. Further, since the tilt of the disk is detected based on the reflected light of the laser beam, the tilt amount currently occurring between the laser beam and the optical disk can be accurately detected, and the correct coma aberration can be obtained. Can be corrected.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an optical pickup device according to a first embodiment in which the present invention is applied to a magneto-optical disk reproducing device.

FIG. 2 is a diagram showing a configuration of a main part of the optical pickup device according to the first embodiment.

FIG. 3 is a schematic diagram for explaining optical rotation directions of a laser beam and reflected light of the optical pickup device according to the first embodiment.

FIG. 4 is a diagram for explaining a configuration of a 4-division optical rotation plate provided in the optical pickup device according to the first embodiment.

FIG. 5 is a diagram showing a light receiving state of reflected light emitted to the first photodetector provided in the optical pickup device according to the first embodiment without tilting the optical disc.

FIG. 6 is a diagram for explaining a state in which the optical disc is tilted.

FIG. 7 is a diagram for explaining a dark line generated in the first photodetector due to the inclination of the optical disc.

FIG. 8 is a diagram for explaining a state in which the optical disc is tilted.

FIG. 9 is a diagram for explaining a dark line generated in the first photodetector due to the inclination of the optical disc.

FIG. 10 is a diagram for explaining a bright line generated in the second photodetector due to the inclination of the optical disc.

FIG. 11 is a diagram showing a configuration of a main part of an optical pickup device according to a second embodiment of the present invention.

FIG. 12 is a diagram showing a configuration of an optical pickup device according to a third embodiment of the present invention.

FIG. 13 is a diagram showing a configuration of a main part of the optical pickup device according to the third embodiment.

FIG. 14 is a diagram for explaining a modified example of the first photodetector in which the light receiving area is adjusted so that the light amounts of the respective light receiving regions are uniform.

FIG. 15 is a diagram for explaining another modification of the first photodetector including two light receiving portions.

FIG. 16 is a diagram showing a configuration of a conventional optical pickup device that detects a tilt of an optical disc to correct coma aberration.

FIG. 17 is a diagram showing a configuration of a main part of the conventional optical pickup device.

FIG. 18 is a diagram showing the configuration of another conventional optical pickup device that corrects the coma aberration by detecting the tilt of the optical disc.

FIG. 19 is a diagram showing a configuration of a main part of another conventional optical pickup device of the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magneto-optical disk 2 Laser light source 3 Collimator lens 4 Beam splitter 4a Beam splitter film 5 Deflection beam splitter 5a Deflection beam splitter film 6 Movable units 6a, 6b Elastic arm fixing part of movable unit 7 Four-division optical rotation plate 8 Objective lens 9 Elastic arm 10 1st photodetector 12 Skew detection circuit 15 2nd photodetector 17 Skew control circuit 30 Fixed wall 31-34 Drive coil 35, 36 Magnet

Claims (13)

[Claims] 1. A laser light source that emits a laser beam for irradiating an optical disk, and a light source that transmits light having a first deflection direction and transmits light having a second deflection direction orthogonal to the first deflection direction. A deflecting beam splitter that reflects light, and a laser beam that has passed through the polarizing beam splitter and an incident region of reflected light that is generated by irradiating the optical disk with the laser beam are clockwise with respect to the optical axis of the laser beam and the reflected light. Direction or counterclockwise direction, each of which rotates at least a predetermined amount of light and emits the rotatory means, and an objective lens that converges the laser beam from the rotatory means and irradiates the optical disc. Elastic support means that elastically supports the objective lens so that it can move in all directions, and receives the reflected light from the polarization beam splitter. Based on the light receiving means for outputting a light receiving signal according to this light quantity and the light receiving signal from the light receiving means, the tilt of the optical disc is detected, and the predetermined tilt is applied to the optical disc according to the detected tilt of the optical disc. An optical pickup device comprising: a control unit that drives and controls the elastic supporting unit so that the laser beam is irradiated at an angle. 2. The optical rotation means rotates the incident light by a predetermined amount in the clockwise direction and outputs the first and third incident regions, and the second and third incident regions rotate by a predetermined amount in the counterclockwise direction and outputs the second incident region. ，
The fourth incident region is radially divided into four equal parts about the optical axes of the laser beam and the reflected light.
2. The optical pickup device according to claim 1, wherein the incident areas are arranged such that adjacent incident areas have different optical rotation characteristics. 3. The light according to claim 2, wherein the light receiving means has a light receiving area for receiving the reflected light from the polarization beam splitter, which is radially divided into four equal parts about the optical axis. Pickup device. 4. The optical pickup device according to claim 3, wherein the objective lens is supported at two points by the elastic supporting means. 5. The objective lens is provided at a position facing each other, a pair of drive coils having two coils inside, and 2 provided near each drive coil.
It is provided in a movable unit composed of two magnets, and the movable unit is supported by two elastic arms at two points so as to be movable in all directions. Optical pickup device. 6. The optical pickup device according to claim 5, wherein the optical rotation means is provided in the movable unit. 7. The optical pickup device according to claim 5, wherein the laser light source, the polarization beam splitter, and the light receiving means are provided in the movable unit. 8. The first rotatory part rotates the incident light by a predetermined amount in the clockwise direction with respect to the optical axes of the laser beam and the reflected light, and outputs the first incident region and the incident light in the counterclockwise direction. The optical pickup device according to claim 1, wherein the optical pickup device is divided into two equal parts into a second incident region which is rotated by a predetermined amount and emitted. 9. The light-receiving means has light-receiving regions arranged in parallel so that the reflected light from the polarization beam splitter is divided into four and received.
The optical pickup device described. 10. The optical pickup device according to claim 9, wherein the objective lens is supported at two points by the elastic supporting means. 11. The objective lens is composed of a pair of drive coils which are provided at positions opposite to each other and have two coils inside, and two magnets which are provided close to the respective drive coils. The optical pickup device according to claim 9, wherein the optical pickup device is provided in a movable unit, and the movable unit is supported by two elastic arms at two points so as to be movable in all directions. 12. The optical pickup device according to claim 11, wherein the optical rotation means is provided in the movable unit. 13. The optical pickup device according to claim 11, wherein the laser light source, the polarization beam splitter, and the light receiving means are provided in the movable unit.