JPH0547009A - Objective lens actuator - Google Patents

Abstract

PURPOSE:To provide an objective lens actuator with high reliability by preventing deterioration of pull-in performance of the servo which makes the light beam spot converged by the objective lenses follow the surface waving and eccentricity of an information recording media, related with an objective lens actuator used for optical recording/reproducing devices, such as a compact disc. CONSTITUTION:A base 1 provided with a supporting axis 31, a bearing 9 which is loaded to the supporting axis 31 in a manner free to rotate and move up/ down, and an objective lens supporting body 10 which holds an objective lens 12 loaded to the bearing 9 are incorporated and a spiral groove is provided on the surface of the supporting axis 31. Thereby, dirt caught at dew condensation in the clearance part between the bearing 9 and the supporting axis 31 coagulates in the groove provided on the surface of the supporting axis 31 and movement in the focusing direction comes to be very smooth. As a result, the pull-in capability into a servo which means the performance by which the light beam spot converged by the objective lens 12 is made to follow the surface deflection and eccentricity of an information recording media is prevented from deteriorating and reliability can be increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens actuator used in an optical recording / reproducing apparatus for recording / reproducing information by condensing a light beam emitted from a light source such as a semiconductor laser on an information recording medium. It is a thing.

[0002]

2. Description of the Related Art A conventional objective lens actuator of this type is constructed as shown in the exploded perspective view of FIG. That is, the base 1 made of a magnetic metal plate fixed between the light source section of the optical recording / reproducing apparatus and the information recording medium is provided with a through hole 2 through which the light beam of the light source passes, and close to the through hole 2. A mounting hole 4 for fixing the support shaft 3 is also provided at the position where the light emitting element 20 and the two-divided light receiving element 21 are mounted on the side facing the through hole 2 so as to face each other. The detector 22 has screws 23a and 23b.
The magnet holding pieces 7a and 7b for holding the arc-shaped magnets 6a and 6b, which are mounted by the through holes 2, the mounting holes 4, and the center of the position detector 22 and which are orthogonal to the straight line, are formed. It is provided to face each other,
On the outside of each of the magnet holding pieces 7a and 7b, arcuate magnetic path pieces 8a and 8b are provided at regular intervals. A bearing 9 that is rotatable and vertically slidable is incorporated in the support shaft 3, and an objective lens holder 10 made of a material such as polyphenylene sulfide resin or epoxy resin is fitted and fixed to the bearing 9. .. In this objective lens holder 10, the objective lens 12 is inserted into the light beam entrance hole 11 provided at a position corresponding to the through hole 2 of the base 1.
Is incorporated. On the other hand, in the objective lens holder 10, a balancer 13 is incorporated at a position facing the objective lens 12, and a position detection pin 14 is incorporated under the balancer 13. Around the objective lens holder 10, a focusing control coil 15 formed in a ring shape and an arc-shaped tracking control coil 16 coupled to the outer circumference thereof.
Are coupled to each other, and both coils 15 and 16 are magnets 6
It is arranged in the space between a and 6b and the magnetic path pieces 8a and 8b. Both coils 15 and 16 are wired on a board B17 attached on the balancer 13, and further wired from the board B17 to the board A5 on the base 1 by a twisted wire 18. A cover 19 is covered over the entire body, and escape windows 19a and 19b are formed at positions corresponding to the objective lens 12, the bearing 9, and the balancer 13.

With such a structure, the focus deviation of the light beam with respect to the surface of the information recording medium 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 focusing control coil 15 and the tracking are detected by the detection signals. A current is applied to the control coil 16 to move the objective lens holder 10 up and down and rotate it by using a magnetic flux that always forms a magnetic field by the magnets 6a and 6b and the magnetic path pieces 8a and 8b. It controls the position.

[0004]

However, in the above-mentioned structure, when the objective lens actuator is condensed, the moisture generated by the condensation between the bearing 9 and the support shaft 3 draws in the dust in the air. Even in the dry state, dust remains in the clearance between the bearing 9 and the support shaft 3. Therefore, the movement in the focusing direction is not smooth, and as a result, there is a problem in that the pull-in performance of pulling the light beam spot focused by the objective lens 12 into the servo that follows the surface wobbling and eccentricity of the information recording medium deteriorates.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an objective lens actuator which is smooth in movement in the focusing direction, has no deterioration in pull-in performance, and is highly reliable. ..

[0006]

In order to solve the above problems, the present invention provides a base provided with a support shaft, a bearing rotatably and vertically movable on the support shaft, and a bearing mounted on the bearing. An objective lens holder for holding an objective lens is provided, and a spiral groove is provided on at least one of the support shaft surface and the bearing inner surface.

[0007]

With the above structure, the dust drawn into the clearance between the bearing and the support shaft during dew condensation is aggregated in the groove provided on at least one of the support shaft surface and the bearing inner surface, so the movement in the focusing direction is very smooth. Can be As a result, it is possible to prevent deterioration of the ability to draw the light beam spot condensed by the objective lens to the servo, which has the ability to follow the surface wobbling and eccentricity of the information recording medium, and improve the reliability. it can.

[0008]

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

(Embodiment 1) FIG. 1 is an exploded perspective view of an objective lens actuator according to a first embodiment of the present invention, and FIG. 2 is a front view of its supporting shaft. The same parts as those of the conventional example are given the same numbers, and the description of the same parts is omitted. In FIG. 1 and FIG. 2, reference numeral 31 is a screw spindle having an outer peripheral groove 32 provided spirally on the surface.

In this case, since the spiral outer peripheral groove 32 is provided on the surface of the screw support shaft 31, the moisture containing dust generated by dew condensation is aggregated in the spiral outer peripheral groove 32 and dried. Dust between the contact surfaces of the screw support shaft 31 and the bearing 9 can be eliminated for a long period of time, and the light beam spot condensed by the objective lens 12 is not disturbed in the information recording medium without hindering the movement in the focusing direction. There is no deterioration in the ability to draw in the servo, which has the ability to follow surface wobbling and eccentricity.

(Embodiment 2) An objective lens actuator according to a second embodiment of the present invention will be described below with reference to FIGS. 3 is a side sectional view thereof, and FIG. 4 is a front sectional view of the bearing. The same parts as those in the conventional example are given the same numbers, and the description of the same parts is omitted. Figure 3,
In FIG. 4, reference numeral 33 is a screw bearing having an inner surface groove 34 spirally provided on the inner surface.

In this case, since the spiral inner surface groove 34 is provided on the inner surface of the screw bearing 33, the water containing dust generated by the condensation is condensed in the spiral inner surface groove 34 and dried, whereby the screw is formed. It is possible to eliminate dust between the contact surface of the bearing 33 and the support shaft 3 for a long period of time, and without disturbing the movement in the focusing direction, the light beam spot condensed by the objective lens is subjected to surface deflection of the information recording medium. However, there is no deterioration in the ability to draw into the servo, which shows the performance to follow eccentricity.

In the above embodiment, the spiral groove is provided on either the surface of the support shaft or the inner surface of the bearing. Of course, the spiral groove may be provided on both of them.

[0014]

As described above, according to the present invention, the base provided with the support shaft, the bearing mounted on the support shaft so as to be rotatable and vertically movable, and the objective lens holding the objective lens mounted on the bearing. A holder, and by providing a spiral groove on at least one of the support shaft surface and the bearing inner surface, moisture containing dust generated by dew condensation aggregates in the spiral groove and is dried. Therefore, it is possible to eliminate dust between the contact surfaces of the support shaft and the bearing for a long period of time. Therefore, it does not impede the movement in the focusing direction, and does not cause deterioration in the ability to draw the light beam spot condensed by the objective lens to the servo which shows the surface wobbling and eccentricity of the information recording medium. The objective lens actuator with excellent reliability can be realized.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an objective lens actuator according to a first embodiment of the present invention.

FIG. 2 is a front view of a support shaft of the objective lens actuator.

FIG. 3 is a side sectional view of an objective lens actuator according to a second embodiment of the present invention.

FIG. 4 is a front sectional view of a bearing of the objective lens actuator.

FIG. 5 is an exploded perspective view of a conventional objective lens actuator.

[Explanation of symbols]

 1 Base 3 Spindle 9 Bearing 10 Objective Lens Holder 12 Objective Lens 15 Focusing Control Coil 19 Cover 22 Position Detector 31 Screw Spindle 32 Spiral Groove 33 Screw Bearing 34 Spiral Groove

Claims (1)

[Claims] 1. A base provided with a support shaft, a bearing rotatably and vertically movable mounted on the support shaft, and an objective lens holder for holding an objective lens mounted on the bearing, An objective lens actuator, wherein a spiral groove is provided on at least one of a support shaft surface and the bearing inner surface.