JPH0391121A - Actuator for optical head - Google Patents

Abstract

PURPOSE:To suppress unrequired resonance in a frequency band area generated due to a gap between a supporting shaft and a bearing by providing a periodic damping member between an objective lens holder and the bearing. CONSTITUTION:The center part of an almost square objective lens holder 31 in one terminal of which an objective lens 29 is assembled and in the other terminal of which a balancer 30 is assembled is coupled with the bearing 28 via the periodic damping member 39 made of silicon rubber or acrylate resin, etc. In such a way, by providing the periodic damping member 39 between the objective lens holder 31 and the bearing 28, the unrequired resonance generated due to the gap between the supporting shaft 23 and the bearing 28 is suppressed, and the unrequired resonance is prevented transmitted to the objective lens 29, which prevents the stability of servo lowering.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical device used in an optical recording/reproducing device that focuses a light beam emitted from a light source such as a semiconductor laser onto an information recording medium to record and reproduce information. This invention relates to a head actuator.

Conventional technology FIG. 4 shows a conventional actuator for an optical head.

It is shown in FIG. FIG. 4 is an exploded perspective view, and FIG. 6 is a perspective view. According to the figure, 1 is a base made of a magnetic metal plate that is fixed between the light source part of the optical recording and reproducing device and the information recording medium, and is provided with a through hole 2 through which the light beam of the light source passes. A mounting hole 4 for fixing the support shaft 3 is provided in a position close to the through hole 2, and a rubber spring 5 is installed on the opposite side of the through hole 2 on a straight line between the mounting hole 4 and the through hole 2. On the orthogonal sides, there is an arc-shaped magnet) 61L protruding in an arc shape, and a magnet holding piece 71L that holds 6bf.
, 7b are provided to face each other, and arcuate magnetic path pieces 81L, 8b are provided at regular intervals on the outside of the respective magnet holding pieces riL, 7b. A bearing 9 that can rotate and slide vertically is incorporated into the support shaft 3, and an objective lens holder 10 is fitted into and fixed to the bearing 9. An objective lens 1 is provided at a position corresponding to the through hole 2 of the base 1 at one end of the objective lens holder 10.
A balancer 13 having a holding pin 12 connected to a rubber spring 5 at the lower end is installed at the other end. Around this objective lens holder 1o, there is a focusing control coil 14 formed in a ring shape, and four arc-shaped tracking control coils A/15 connected to the outer periphery of the focusing control coil 14.
are coupled, and both coils N are arranged in the gap between the magnets 6N, 6b and the magnetic path pieces 81L, 8. A cover 16 is placed over these, and the objective lens 11. Bearing e, balancer 1
Escape windows '17 and 18 are formed at positions corresponding to 3.

With this configuration, the out-of-focus of the light beam with respect to the information recording medium surface and the track groove deviation of the light beam with respect to the track groove of the information recording medium surface are detected, and the detection signals are used to control the focusing control coil/L/14. ) Applying current to rough king control carp/L'115, magnet) 6
1k, 6b and magnetic path piece Sa.

The position of the objective lens 11 is controlled by moving the objective lens holder 1o up and down and rotating it by constantly utilizing the magnetic flux generated by the magnetic field 8b.

Problems to be Solved by the Invention However, in the above configuration, it is necessary to provide a small gap between the bearing 9 and the support shaft 11 in order to vertically move and rotate the lens holder 1o. Objective lens holder 10. Bearing 9. Focusing control coil 1
4. Tracking control carp/l/15. balancer 1
Unnecessary resonance occurs within the frequency band in the movable part constituted by 3, resulting in stabilization of servo performance, which is the ability to make the light beam spot focused by the objective lens 11 follow the surface runout and eccentricity of the information recording medium. There was a problem with poor sex.

Means for Solving the Problems In order to solve the above problems, the present invention provides a vibration damping material between the objective lens holder and the bearing.

Effect: With the above configuration, unnecessary resonance generated between the support shaft and the bearing can be suppressed, and as a result, the light beam spot focused by the objective lens can be suppressed from the surface deflection of the information recording medium.
This can improve the stability of servo performance, which indicates the ability to follow eccentricity.

Embodiment Hereinafter, one embodiment of the actuator for an optical head of the present invention will be explained with reference to FIGS. 1 and 2. FIG. 1 is an exploded perspective view, and FIG. 2 is a side sectional view.

In the figure, reference numeral 20 denotes a base made of magnetic metal. A circular recess 21 is formed on this base 2o, and a light beam from a light source passes through a part of this recess 21. A mounting hole 24 for fixing the support shaft 23 is provided at the center of the recess 21, and a mounting hole 24 for fixing the support shaft 23 is provided at the center of the recess 21.
A rubber spring 26 is attached within the recess 21 on the opposite side of the spring 2.

Further, an arc-shaped magnet holding piece 26a is disposed at a position opposite to each other across the line connecting the center of the light beam through hole 22 and the center of the support shaft 23 within the recess 21.

26b is provided so as to protrude upward, and similarly arcuate magnetic path pieces 271L, 27b are formed on the outside of the recess 21 on the outer periphery of the magnet holding pieces 261L, 26b.

A support shaft 23 is fixed to the mounting hole 24 of the base 20, and a bearing 2B that is rotatable about the axis of the support shaft 23 and slidable up and down is incorporated in the support shaft 23.

This bearing 28 has a substantially rectangular objective lens holder 31 in which an objective lens 29fI is incorporated at one end and a balancer 3o at the other end, and the center portion thereof is made of silicone rubber.

They are connected via a vibration damping material such as acrylate resin using 39-karat gold. The objective lens 29 is installed in the position corresponding to the light beam through hole 22, and the balancer 3o is installed in the objective lens holder 31 in the position corresponding to the rubber spring 26! The holding pin 32 provided at the lower end of the balancer 3o is attached to the rubber spring 2.
6. This holding pin 32 and rubber spring 26
Due to this combination, even if the objective lens holder 31 rotates and slides up and down, it always returns to a predetermined position.

Further, on the outer circumferential surface of the magnet holding pieces 281L and 2sb, there is a magnet (33a) formed in an arc shape.

33b is fixed, and the outer peripheral surface of the magnets 33a, 33m) and the magnetic path piece 27! A gap is formed between L and 27b.

A focusing control coil 34 wound in a ring shape is fixed to the outer periphery of the objective lens holder 31, and four arc-shaped coils p are connected to the outer periphery of this focusing control coil/I/34. The tracking control coils/L'35 are connected at predetermined intervals. Both coils 34゜36 are the above magnets) 331L
, 33b and the magnetic path pieces 27a, 27b.

A cover 36 is placed over these, and window holes 37 are placed on the upper surface of the cover 36 at positions corresponding to the objective lens 29 and bearing 28 and at positions corresponding to the balancer 30.
．． 38 is formed, and the window hole 37 is the objective lens 2.
The window hole 38 allows the light beam passed through the window hole 38 to pass through the window hole 38, and serves as a relief to prevent the bearing 28, which moves upward when the objective lens holder 31 moves upward, from coming into contact with it. This is for escape to prevent the balancer 30 from coming into contact with it when it moves upward.

In the above manner, a light beam is emitted from the light source, the light beam is focused on the information recording medium surface through the objective lens, and the focus of the light beam spot and the track on the recording information medium surface are determined. Detects the track groove misalignment with respect to the groove,
Coil for controlling current gold focusing according to the detected amount /
L'34 and the tracking control coil 36 are applied to the magnets 331L, 331) and the magnetic path piece 27! L, 27
Using the magnetic flux of the magnetic circuit formed by b, the objective lens holder 31, which has both coils 34 and 35 fixed to its outer periphery, is rotated or moved up and down with respect to the axis of the support shaft 23, and the focusing direction and tracking are performed. The objective lens follows the direction.

In this case, since the vibration damping material 39 is provided between the objective lens holder 31 and the bearing 28, it is possible to suppress unnecessary resonance generated by the gap between the support shaft 23 and the bearing 2B, and the objective lens 29 does not require vibration damping. It does not transmit resonance and does not cause a decrease in servo stability. It is also possible to use a vibration damping adhesive as the vibration damping material 39 provided between the objective lens holder 31 and the bearing 2B in the above configuration.

Next, an embodiment of an actuator for an optical head according to the present invention will be described with reference to FIG. FIG. 3 is a side cross section. The same parts as the conventional button are given the same number +1, and the explanation will be omitted. In the figure, 46 is a vibration damping material coated on the support shaft 47 provided in the mounting hole 46 of the base 41.

In this case, since the surface of the support shaft 47 that fits with the bearing is coated with silicone rubber, acrylate resin, etc. as a vibration damping material 48, unnecessary resonance generated by the gap between the bearing 60 and the support shaft 47 can be suppressed. Therefore, unnecessary resonance is not transmitted to the objective lens 51, and the stability of the servo is not deteriorated.

Effects of the Invention As described above, in the present invention, since the vibration damping material is provided between the objective lens holder and the bearing, it is possible to suppress unnecessary resonance within the frequency band caused by the gap between the support shaft and the bearing.

As a result, the stability of the servo performance, which indicates the ability to make the beam spot focused by the objective lens follow the surface runout and eccentricity of the information recording medium, can be improved, and wrinkles can be prevented from external disturbances such as vibrations. Therefore, it is possible to provide an actuator for an optical head that has excellent vibration resistance and does not impair tracking performance even when the optical head is moved.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of an embodiment of the optical head actuator of the present invention, FIG. 2 is a side sectional view of the same, and FIG. 3 is a side sectional view of an embodiment of the optical head actuator of the present invention.
FIG. 4 is an exploded perspective view of a conventional actuator for an optical head, and FIG. 5 is a perspective view of the same. 20...Base, 23...Spindle, 28.
····bearing. 29... Objective lens, 31... Objective lens holder, 39... Vibration damping material.

Claims (2)

[Claims] (1) A base provided with at least a support shaft, a bearing mounted on the support shaft so as to be rotatable and movable up and down, an objective lens holder mounted on the bearing via a vibration damping material, and this objective lens holder. An actuator for an optical head consisting of an objective lens held in a material. (2) A base provided with at least a support shaft, a bearing mounted on the support shaft so as to be rotatable and movable up and down via a vibration damping material, an objective lens holder mounted on this bearing, and this objective lens holder. An actuator for an optical head consisting of an objective lens held in a material.