JPH05189797A - Optical pickup device - Google Patents

Abstract

PURPOSE:To provide the optical pickup device which can access the recording surfaces on both sides of an optical disk at a high speed without turning over the optical head by means of an optical pickup head of a sepn. type and can suppress the loss of the light quantity of a laser beam, the increase of a phase difference and the increase of aberrations. CONSTITUTION:The optical pickup head 1 is separated to a moving optical part 1a and a stationary optical part 1b. This moving optical part 1a is disposed to face the respective recording surfaces of the optical disk 4. This stationary optical part 1b operates to turn relative to a turning shaft 16 in order to align its optical axis to the optical axis of the arbitrary one moving optical part lb. The position where the optical axes align are detected by an optical position detector 17. The laser beam L is emitted from an LD 6 in the stationary optical part 1b where the optical axes are aligned. This beam is collimated by a collimation lens 7 and the collimated beams of light are passed through a polarization beam splitter 8 and are reflected by a mirror 18. These beams are made incident on the moving optical part 1'; which is linearly actuated by a linear motor 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording apparatus such as an optical disk apparatus, a magneto-optical disk apparatus, a phase change type optical disk apparatus or the like, and an optical pickup apparatus for recording / reproducing or erasing information on an optical disk or a magneto-optical disk.

[0002]

2. Description of the Related Art Optical discs (including magneto-optical discs) are
It is an information recording medium characterized by high recording density and portability, and usually has a disc shape, and information can be recorded and reproduced on both sides of the disc. In order to record / reproduce information on / from an optical disc, an optical pickup device performs a tracking operation and a focusing operation on an information track by a light spot of a light beam.

FIG. 3 is a sectional view showing an example of a conventional optical pickup device, and the operation of the optical pickup device when reproducing information on an optical disk will be described with reference to FIG. The optical pickup head 1 is linearly moved along the rail 3 by the linear motor 2, and the optical disk 4 is driven by the motor 5
Performs a rotational movement by. In the optical pickup head 1,
Laser beam L emitted from laser diode (LD) 6
Is collimated by the collimator lens 7, passes through the polarization beam splitter 8, and is reflected by the total reflection prism 9.
It is condensed by the objective lens 11 whose focusing is controlled by the lens actuator 10 and forms a light spot on the recording surface on the optical disc 4. The light spot of the laser beam L scans the recording surface of the optical disc 4 by the linear movement of the optical pickup head 1 and the rotational movement of the optical disc. The laser beam L reflected by the optical disk 4 follows the same path as that at the time of incidence to the polarization beam splitter 8, and the photodetector at the polarization beam splitter 8 is followed.
It is reflected by 12 and is detected as a reproduction signal by the photo detector 12. The reproduction signal output by the photo detector 12 is amplified by the head amplifier 13 and output to the data processing unit.

In the optical pickup device having the above-described structure, recording / reproducing can be performed only on the information recording surface of the optical disc 4 facing the optical pickup head 1, and in order to perform recording / reproducing on another information recording surface, the optical disc 4 is used. Need to flip.

In order to record / reproduce on both sides of the optical disc without inverting it, an optical pickup head having the same structure as the optical pickup head 1 of FIG. 3 is arranged to face each information recording surface of the optical disc. There is.
Further, in Japanese Patent Laid-Open No. 2-165439, as shown in FIG.
The optical pickup head 1 of the optical up device is movable to the optical unit 1.
An optical pickup device is shown which is separated into a, a fixed optical section 1b, and a light distribution section 1c. The movable optical unit 1 a includes an objective lens 11, a lens actuator 10, a total reflection prism 9 and a linear motor 2, and performs a linear operation along a rail 3. The fixed optical unit 1b includes the LD 6 and the collimator lens 7.
A polarization beam splitter 8, a photodetector 12, and a head amplifier 13 are provided, and the laser beam L is emitted and the laser beam L reflected by the optical disc 4 is detected as a reproduction signal, and the reproduction signal is amplified. The movable optical unit 1a is arranged so as to face the two information recording surfaces of the optical disc, respectively, and the laser beam L from the fixed optical unit 1b is disposed in the two movable optical units 1a.
To selectively distribute the light to one of the
Is equipped with a variable phase plate 14, a λ / 4 plate 15 and a polarization beam splitter 8a, which are optical distribution means, distributes the laser beam L to any one movable optical part 1a, and reflects the reflected light from the optical disk 4. It also serves as a route.

[0006]

In the above-described pickup device, in the optical pickup device having the structure shown in FIG. 3, an LD 6, a collimator lens 7, a polarization beam splitter 8, a photodetector 12, and a head amplifier are provided in an optical pickup head 1 which is entirely movable. Since the optical pickup head 1 is driven by the linear motor 2, there is a limit to the size reduction and weight reduction of the optical pickup head 1, and the target information of the information recording surface on the optical disc 4 is required. There is also a limit to the reduction in time to access a truck.
If the optical disc 4 is not inverted, only one information surface of the optical disc 4 can be accessed, and the actual recordable and reproducible information amount is half the total information amount of the optical disc.

The optical pickup head 1 shown in FIG. 3 is used to access each information surface without inverting the optical disk.
In the case where the optical pickup head having the same structure as that of the above is arranged on both recording surfaces of the optical disk 4, the amount of accessible information increases, but the shortening of access time is limited as in the case of FIG. There is.

Further, as shown in FIG. 4, the optical pickup head 1
If the movable optical unit 1a, the fixed optical unit 1b, and the light distribution unit 1c are separated, the movable optical unit 1a can be made smaller and lighter, and the access time to a predetermined information track on the information recording surface of the optical disk 4 can be reduced. Can be shortened, but the light distribution unit 1
In the optical path of c, the variable phase plate 14 and λ / 4
Since the plate 15 and the polarization beam splitter 8a are used,
A loss of the light amount of the laser beam L, an increase in phase difference, and an increase in aberration occur.

The object of the present invention is to enable high-speed access to both sides of the information recording surface without inverting the optical disk,
Another object of the present invention is to provide an optical pickup device capable of suppressing the loss of light quantity of a light beam, an increase in phase difference, and an increase in aberration.

[0010]

In order to achieve the above-mentioned object, the present invention provides a tracking operation which is installed facing both recording surfaces of an optical information recording medium capable of recording / reproducing or erasing information. Light having a plurality of movable optical parts for performing a focusing operation, a fixed optical part having a light beam emitting means for emitting a light beam to an optical information recording medium, and a light receiving means for receiving a reflected light beam from the recording medium In the pickup device, the fixed optical section is movable in order to match the optical axis of the light beam with the optical axis of one movable optical section selected for use.

Further, the fixed optical unit is characterized in that the optical axis of the light beam is made to coincide with each other by performing a rotating operation with respect to the rotating shaft.

Further, the fixed optical section is characterized in that the optical axis of the light beam is aligned with each other by performing a linear operation with respect to the linear axis.

[0013]

According to the above means, the optical pickup device is
A plurality of movable optical sections facing the recording surfaces on both sides of the optical information medium, and a fixed optical section which is movable to match the optical axis of the light beam with one optical axis of the plurality of movable optical sections. By separating the optical disc and the optical disc from each other, the information surfaces on both sides of the optical information medium can be accessed without inverting the optical disc, and the movable optical unit for performing the tracking operation can be reduced in size and weight.

Further, the fixed optical section performs a rotating operation with respect to the rotating shaft or a linear operation with respect to the linear axis, so that the optical axis of the light beam also performs a rotating operation or a parallel operation. In the conventional separation type optical pickup head, the number of optical components arranged in the optical path of the light beam emitted from the fixed optical unit is reduced, and then the light beam is emitted with respect to the optical axis of one movable optical unit selected for use. The optical axes of can be matched.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the configuration of the first embodiment of the present invention, in which an optical pickup head 1 comprises a movable optical section 1
The movable optical unit 1a is separated into a and the fixed optical unit 1b.
Are arranged so as to face the recording surfaces on both sides of the optical disc 4.

The operation of reproducing information on the recording surface of the optical disc 4 will be described with reference to FIG. The fixed optical unit 1b is
In order to match the optical axis with any one movable optical unit 1a, a rotating operation (in the direction of arrow A) is performed on the rotating shaft 16,
The position where the optical axes match is detected by the optical position detector 17. In the fixed optical unit 1b where the optical axes of the light beams coincide with each other, the laser beam L is emitted from the LD 6, collimated by the collimator lens 7, passed through the polarized beam splitter 8, reflected by the mirror 18, and linearized by the linear motor 2. It is incident on the movable optical unit 1a that operates. Mirror here 18
Can be an oscillating mirror (galvano mirror) having a control mechanism for the tracking operation of the light spot.
In the movable optical unit 1a, the total reflection prism 9 reflects the laser beam L, and the objective lens 11 whose focusing is controlled by the actuator 10 causes the laser beam L to move.
Forms a light spot on the recording surface of the optical disc 4.
Reproduction laser beam L reflected on the recording surface of the optical disc 4.
Follows the same path as when it is incident, and the fixed optical unit 1
It reaches the polarization beam splitter 8 of b, is reflected by the photo detector 12, and is detected by the photo detector 12 as a reproduction signal.

In the optical pickup device having the above structure, the movable optical section 1a driven by the linear motor 2 for performing the tracking operation is made compact and lightweight, and the recording surface of the optical disk 4 can be accessed at high speed. In addition, the fixed optical unit 1b is rotated, and one optical axis of the movable optical unit arranged to face both recording surfaces of the optical disc 4 is aligned with the optical axis of the light beam, so that the optical disc 4 is reversed. However, since the recording surfaces on both sides of the optical disk 4 can be accessed and the optical component disposed in the optical path of the laser beam L emitted from the fixed optical unit 1b is only the mirror 18, the loss of the light amount of the laser beam L is lost. The increase of the phase difference and the increase of the aberration are very small.

FIG. 2 is a sectional view showing the structure of the second embodiment of the present invention. As in the first embodiment of FIG. 1, the optical pickup head 1 has a movable optical section 1a and a fixed optical section 1b. Separated. The fixed optical unit 1b includes a worm shaft 1 which is a linear shaft.
It is supported by 9, and the worm shaft is rotated by the motor 20 to perform a linear operation (in the direction of arrow B), and the optical position detection device 17 detects the coincidence of the optical axis with the movable optical unit 1a. In this case, it is not necessary to provide a mirror in the optical path of the laser beam L, and the laser beam L emitted from the fixed optical axis 1b directly enters the movable optical unit 1a. The subsequent reproducing operation is performed in the same manner as described with reference to FIG.

Also in the optical pickup device having the above-mentioned structure, as in the first embodiment, the recording surfaces on both sides of the optical disk 4 can be accessed at high speed, and the light amount of the laser beam L emitted from the fixed optical section 1b is high. The loss, the increase in the phase difference, and the increase in the aberration are further reduced because there is no optical component in the optical path of the laser beam L.

[0021]

As described above, according to the present invention,
A plurality of movable optical units, which are arranged to face each other on both sides of the optical information recording medium, and a fixed optical unit that is movable to align the optical axis of the light beam with one optical axis of the plurality of movable optical units. It is possible to provide an optical pickup device that enables high-speed access to both recording surfaces of the optical information recording medium.

Further, the fixed optical section rotates about the rotating shaft or moves linearly about the linear axis, whereby the number of optical components arranged in the optical path of the light beam is reduced. Therefore, it is possible to provide an optical pickup device capable of suppressing the light amount loss of the light beam, the increase of the phase difference, and the increase of the aberration.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of a first embodiment of an optical pickup device of the present invention.

FIG. 2 is a sectional view showing the configuration of a second embodiment of the optical pickup device of the present invention.

FIG. 3 is a cross-sectional view showing an example of the configuration of a conventional optical pickup device.

FIG. 4 is a cross-sectional view showing an example of the configuration of an optical pickup device disclosed in Japanese Patent Laid-Open No. 2-165439.

[Explanation of symbols]

1 ... Optical pickup head, 1a ... Movable optical part, 1b
… Fixed optics, 2… Linear motor, 3… Rails,
4 ... Optical disc, 5 ... Motor, 6 ... LD, 7 ... Collimating lens, 8 ... Polarizing beam splitter, 9 ... Total reflection prism, 10 ... Actuator, 11 ... Objective lens, 12 ... Photodetector, 13 ... Head amplifier,
16 ... Rotation axis, 17 ... Optical position detector, 18 ... Mirror,
19 ... Worm shaft, 20 ... Motor.

Claims (3)

[Claims] 1. A plurality of movable optical parts for performing a tracking operation and a focusing operation, which are installed so as to face both recording surfaces of an optical information recording medium capable of recording / reproducing or erasing information, and a light beam is optically emitted. In an optical pickup device comprising a fixed optical unit having a light beam emitting unit for emitting to an information recording medium and a light receiving unit for receiving a reflected light beam from the recording medium, one fixed optical unit is selected for use. An optical pickup device, which is movable in order to match the optical axis of a light beam with the optical axis of a movable optical unit. 2. The optical pickup device according to claim 1, wherein the fixed optical unit is configured to match the optical axes of the light beams by performing a rotating operation with respect to the rotating shaft. 3. The optical pickup device according to claim 1, wherein the fixed optical unit is configured to align the optical axes of the light beams by performing a linear operation with respect to the linear axis.