JPS6215867Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a video disc, a digital
This invention relates to an optical pick-up device used for recording and reproducing information on audio discs, etc.

Generally, this kind of optical pickup device is usually constructed of an optical system using a semiconductor laser, a lens, a reflecting mirror, etc., and an optical pickup device as shown in FIG. 1 is known.

FIG. 1 is a schematic diagram showing the configuration of a conventional optical pickup device. In the figure, 1 is a semiconductor laser, 2 is a collimator lens, 3 is a polarizing beam splitter, 4 is a quarter wavelength plate, and 5 is a Galvanometer mirror, 6 an objective lens, 7 an objective lens barrel support, 8 a converging lens, 9 a 4-split optical sensor, 10
is a light shielding plate, 11 is a focus actuator,
12 is a tracking actuator, 13 is a disk which is a recording medium, and 14 is a disk drive motor.

Disk 13, which is a recording medium such as a video disk, digital audio disk, etc.
is rotated at a predetermined speed by a disk drive motor 14. A laser beam from a semiconductor laser 1 passes through a collimator lens 2, reaches a polarizing beam splitter 3, is deflected by 90 degrees by the polarizing beam splitter 3, passes through a quarter-wave plate 4, and reaches a galvano mirror 5. The laser beam is further deflected by 90 degrees by the galvano mirror 5 and focused on the information recording surface of the disk 13 via the objective lens 6. The reflected light from the information recording surface returns to the polarizing beam splitter 3 in the reverse order as described above, travels straight through the polarizing beam splitter, and passes through the light shielding plate 10 and the converging lens 8.
The light enters the 4-split optical sensor 9 through the 4-split optical sensor 9. The optical sensor 9 receives the reflected light from the information recording surface and outputs a focusing error signal, a tracking error signal, and a readout signal for information recorded on the disk 13.

The objective lens 6 causes the laser beam from the semiconductor laser 1 to follow the vertical vibration of the disk 13 that occurs as the disk 13 rotates.
The drive is controlled so as to focus on the information recording surface No. 3. That is, the focus actuator 11
is controlled via a servo drive system (not shown) using the focusing error signal, thereby driving and controlling the objective lens 6 in a direction perpendicular to the information recording surface of the disk 13. Similarly, the galvanometer mirror 5 is operated by the tracking actuator 12 based on the above-mentioned tracking error signal.
The drive is controlled in a direction of 45 degrees with respect to the information recording surface of the disk 13. As a result, the laser beam from the semiconductor laser 1 follows the deviation in the radial direction of the information track on the disk 13 caused by the eccentricity of the disk 13, and is always accurately focused on the information track on the disk 13 while capturing information. Track the track.

In such a conventional pick-up device, in order to prevent the disk 13 from coming into contact with the optical pickup device, the distance between the information recording surface of the disk 13 and the objective lens 6 of the optical pickup device, that is, the working distance WD, is set large. It's on. For this reason, the distance between the information recording surface of the disk 13 and the optical sensor 9 is relatively large, also due to the structure of the optical system of the optical pickup device using the galvanometer mirror 5 and the like.

When such an optical pickup device is used in a recording/reproducing device for a video disk, an audio disk, etc., the information recording surface of the disk 13 is tilted with respect to the objective lens 6 of the optical pickup, and due to the rotation of the disk 13. If the vertical vibration of the disk 13 is large, the reflected light from the information recording surface of the disk 13 may pass deviated from the central axis and not return to the optical sensor 9, as shown by the optical paths d and e of the reflected light. arise. Therefore, optical disk players and the like using such optical pickup devices have the disadvantage that the tilt of the disk 13 and the vertical wobbling caused by the rotation of the disk 13 must be minimized as much as possible.

The purpose of the present invention is to provide an optical pickup device that eliminates the drawbacks of the prior art described above, is small, lightweight, and can reduce the distance between the information recording surface of the disk and the optical sensor. The purpose is to ensure that the reflected light from the information recording surface of the disk always returns to the optical sensor even if the disk is shaken or tilted to some extent.

In order to achieve this purpose, the present invention houses an optical system including an objective lens, a quarter-wave plate, a polarizing beam splitter, a collimator lens, a semiconductor laser, an optical sensor, etc. in one optical pickup tube, This optical pickup tube is characterized by being held by an elastic support so that it can be driven in two-dimensional directions by magnetic force.

Hereinafter, embodiments of the optical pickup device according to the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram showing an embodiment of the optical pickup device according to the present invention, and FIGS. 2a to 2c are a side view, a front view, and a perspective view, respectively. In the figure, a semiconductor laser 1, a collimator lens 2,
The polarizing beam splitter 3, 1/4 wavelength plate 4, objective lens 6, 4-split sensor 9, disk 13 as a recording medium, and disk drive motor 14 are the same as in the case of FIG. 1, and 15 is an optical pickup tube. , 16
17 is a mounting frame, 17 is an elastic support, 18 is a rigid protrusion, 19, 20, 21 are first, second and third permanent magnets, and 22, 23 are coils.

In the present invention, the optical pickup tube 15 includes all the optical systems that make up the optical pickup, namely, the semiconductor laser 1, the collimator lens 2, the polarizing beam splitter 3, the 1/4 wavelength plate 4,
An objective lens 6 and an optical sensor 9 are housed therein. The optical pickup tube 15 is attached to the other end of an elastic support 17 which is movable in two dimensions and whose one end is fixed to the attachment frame 16, and is held in a cantilevered manner by the attachment frame 16. This support 17 is
In the present invention, as shown in the figure, two metal leaf springs 17' and 17'' are combined at right angles so that they can move in two dimensions, but they may also be constructed of an elastic material such as rubber. .

A rigid protrusion 18 is further provided at the other end of the elastic support 17, that is, on the side that holds the optical pickup tube 15.
A first permanent magnet 19 is attached to the tip of the protrusion 18 . "U"-shaped second and third permanent magnets 2 are arranged together with the first permanent magnet 19 to form a magnetic loop for driving the first permanent magnet 19 in two orthogonal directions.
0 and 21 are attached to the mounting frame 16. The magnetic loop formed by these first to third permanent magnets 19 to 21 works together with the elastic support 17 to hold the optical pickup tube 15 in a predetermined position, and also drives the optical pickup tube 15. used for That is, coils 22 and 23 are wound around the second and third permanent magnets 20 and 21, and these coils 22 and 23 receive focusing error and tracking error signals obtained from the optical sensor 9. It is controlled via a servo control system (not shown) based on As a result, the first permanent magnet 19 is driven and controlled in two-dimensional directions, and the optical pickup tube 15 is moved through the rigid protrusion 18 in directions that compensate for focusing errors and tracking errors, that is, the Z-axis direction and the X-axis direction in the drawing. The drive will be controlled in the direction.

Since the optical pickup device according to the present invention performs the focusing error and tracking error compensation operation by driving one permanent magnet, the weight of the movable parts can be reduced. Since responsiveness is improved, it is possible to reduce the distance between the lens and the disk, that is, the working distance WD. Therefore, the optical pickup device according to the present invention can increase the numerical aperture NA, and therefore the spatial frequency (V
_c ]2NA/λ; λ = wavelength of laser light) can be made large, and the distance between the disk and the optical sensor can be made small, so vertical vibration of the disk,
It can operate more stably against tilt. Furthermore, the optical pick-up device according to the present invention can hold the optical pick-up tube in a stationary state using a magnetic loop made of permanent magnets even when no control is performed to compensate for focusing errors and tracking errors. Therefore, sufficient servo control can be performed without using the levitation effect due to the dynamic pressure accompanying the rotation of the disk.

As explained above, according to the present invention, it is possible to provide an optical pickup device that is small and lightweight and has high performance.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an optical pickup device according to the prior art, and FIGS. 2a, b, and c are block diagrams of an embodiment of an optical pickup device according to the present invention. DESCRIPTION OF SYMBOLS 1... Semiconductor laser, 2... Collimator lens, 3... Polarizing beam splitter, 4... 1/4 wavelength plate, 5... Galvano mirror, 6... Objective lens, 7... Objective lens support, 8 ...Convergent lens, 9...Four-split optical sensor, 10... Light shielding plate, 1
DESCRIPTION OF SYMBOLS 1... Focus actuator, 12... Tracking actuator, 13... Disk as a recording medium, 14... Disk drive motor, 15... Optical pick-up cylinder, 16... Mounting frame, 17... Elastic support body , 18... rigid protrusion,
19, 20, 21...first, second, and third permanent magnets, 22, 23...coil.

Claims (1)

[Scope of utility model registration request] By focusing the laser beam on the recording surface of the information recording disk and detecting the reflected light,
In an optical pickup device that obtains focusing error signals, tracking error signals, and information detection signals, a single light beam containing an objective lens, a quarter-wave plate, a polarizing beam splitter, a collimator lens, a semiconductor laser, and an optical sensor is used. a pick-up tube, an elastic support member such as a rubber elastic body having one end fixed to hold the optical pick-up tube or a leaf spring movable in two orthogonal axes, and a support body protruding from the side of the elastic support body that supports the optical pick-up tube. a first permanent magnet provided on the rigid protrusion; second and third permanent magnets having a substantially U-shape that form a magnetic loop for driving the first permanent magnet in two orthogonal axes; and two sets of driving coils wound around the second and third permanent magnets, and the optical pickup cylinder is driven via the first permanent magnet by magnetic force using the driving coils. An optical pickup device characterized in that it is capable of compensating for focusing errors and tracking errors.