JPH0547008A - Objective lens actuator - Google Patents

Abstract

PURPOSE:To stabilize servo performance by providing an acrylate resin material for suppressing vibrations between a coil for focusing control and coil for tracking control and an objective lens holder. CONSTITUTION:This objective lens actuator is constituted by providing the acrylate resin material 35 between the coil 33 for focusing control and the objective lens holder 28 and curing only the part near the surface of this acrylate resin material 35 to hold the resin material internally uncured. The attenuation rate of a moving part constituted of the objective lens 30, the objective lens holder 28, the acrylate resin material 35, the coil 33 for focusing control, etc., is, thereupon, increased. A resonance peak value can be decreased in this way and the light beam spot to be condensed by the objective lens 30 can be made to stably follow up the surface waving and eccentricity of an information recording medium.

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. Is.

[0002]

2. Description of the Related Art A conventional objective lens actuator will be described below.

FIG. 4 is a perspective view of a conventional objective lens actuator. In FIG. 4, reference numeral 1 denotes a base made of a magnetic material which is fixed between the light source section of the optical recording / reproducing apparatus and the information recording medium, and the base 1 has a through hole (not shown) through which the light beam of the light source passes. And a mounting hole (not shown) for fixing the support shaft 2 is provided at a position close to the through hole, and the magnet is provided on a straight line orthogonal to the straight line connecting the center of the through hole and the center of the mounting hole. Magnet holding portions 4a and 4b holding 3a and 3b are provided so as to face each other. Further, magnetic path pieces 5a and 5b are provided inside the respective magnet holding portions 4a and 4b with a constant interval. A bearing 6 that can rotate and slide vertically is provided on the support shaft 2.
The bearing 6 is fixed to the objective lens holder 7. In this objective lens holder 7, an objective lens 8 is incorporated in a light beam entrance hole (not shown) provided at a position corresponding to the through hole of the base 1, and at a position facing the objective lens 8. A balancer (not shown) is incorporated. A focusing control coil 9 and a tracking control coil 10 coupled to the outer periphery of the objective lens holding body 7 are firmly coupled to each other, and are arranged in a gap between the magnets 3a and 3b and the magnetic path pieces 5a and 5b. Has been done.

With such a configuration, 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 9 and the tracking are detected according to the detection signals. An electric current is applied to each of the control coils 10, and an electromagnetic force is generated by using a magnetic field formed by the magnets 3a and 3b and the magnetic path pieces 5a and 5b, so that the objective lens holder 7 is supported on the spindle 2. The position of the objective lens 8 is controlled by driving in the vertical and rotating directions.

[0005]

However, in the above-mentioned conventional structure, the objective lens 8 and the objective lens holding body 7 are firmly bonded by the adhesive, so that the objective lens 8, the objective lens holding body 7 and the bearing are formed. 6, the vibration amplitude of higher-order resonance in the focusing direction and the tracking direction of the movable portion constituted by the focusing control coil 9, the tracking control coil 10 and the balancer was large, and the vibration suppressing effect was small. As a result, there is a problem in that the stability of the servo performance, which is the performance of causing the light beam spot condensed by the objective lens 8 to follow the surface deflection and eccentricity of the information recording medium, is poor.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an objective lens actuator which suppresses vibration of higher-order resonance of a movable portion and has excellent servo performance.

[0007]

In order to solve the above problems, the present invention provides an objective lens holder for holding an objective lens, a focusing direction parallel to the optical axis of the optical system, and a vertical direction. A control coil that is driven in the tracking direction, an acrylate resin material is sandwiched between the objective lens holder and the control coil, and only the vicinity of the surface of the acrylate resin material is cured to uncure the inside. The configuration is left as it is.

[0008]

With the above structure, the damping ratio of the movable portion can be increased, and the resonance peak value at the higher resonance frequency in the focusing direction and the tracking direction of the movable portion can be suppressed low. As a result, it is possible to enhance the stability of the servo performance that shows the performance of causing the light beam spot focused by the objective lens to follow the surface wobbling and eccentricity of the information recording medium.

[0009]

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, FIG.
Is a sectional view thereof. In FIGS. 1 and 2, reference numeral 21 is a base made of a magnetic material, and a light beam through hole 22 for passing a light beam from a light source is provided in the base 21. A mounting hole 24 for fixing the support shaft 23 is provided near the center of the base 21. Further, magnet holding portions 25a and 25b are provided so as to project upward at positions facing each other across a line connecting the center of the light beam through hole 22 and the center of the support shaft 23. Magnetic path pieces 26a and 26b are formed inside 25a and 25b. A support shaft 23 is fixed to the mounting hole 24 of the base 21, and a bearing 27 that is rotatable with respect to the axis of the support shaft 23 and is vertically movable is incorporated in the support shaft 23. The bearing 27 is connected to the central portion of the objective lens holder 28. An objective lens 30 is incorporated in the objective lens holder 28 above a light beam entrance hole 29 provided therein, and a balancer 31 is incorporated in a position corresponding to the objective lens 30 with respect to the support shaft 23. ing.

Magnets 32a and 32b are fixed to the inner peripheral surfaces of the magnet holding portions 25a and 25b, and a gap is formed between the inner peripheral surfaces of the magnets 32a and 32b and the magnetic path pieces 26a and 26b. A focusing control coil 33 wound in a ring shape is fixed to the outer periphery of the objective lens holder 28 via an acrylate resin material 35. The acrylate resin material 35 is hardened only in the vicinity of the surface, and the inside thereof remains uncured. A tracking control coil 34, which is formed by connecting four coils, is coupled to the outer periphery of the focusing control coil 33 with a predetermined interval. Both coils 33, 34
Are magnets 32a and 32b and magnetic path pieces 26a and 26b.
It is placed in a magnetic field formed between and.

With the above-described structure, a light beam is emitted from the light source, and the light beam is focused on the surface of the information recording medium through the objective lens 30, the defocus of the light beam spot and the track on the surface of the information recording medium. Detects track groove deviation from the groove. Then, a current corresponding to the detected amount is applied to the focusing control coil 33 and the tracking control coil 34, and the magnets 32a and 32b and the magnetic path piece 2 are applied.
Focusing control coil 33 is generated by an electromagnetic force generated by using a magnetic flux of a magnetic circuit formed by 6a and 26b.
And the objective lens holder 28 having the tracking control coil 34 fixed to the outer periphery is rotated or moved up and down with respect to the axis of the support shaft 23, and the movement causes the objective lens 30 to follow the focusing direction and the tracking direction. ..

In the objective lens actuator of this embodiment, an acrylate resin material 35 is provided between the focusing control coil 33 and the objective lens holder 28, and only the vicinity of the surface of the acrylate resin material 35 is hardened so that the inside of the objective lens actuator is not covered. By leaving it cured, the objective lens 3
0, the objective lens holder 28, the bearing 27, the acrylate resin material 35, the focusing control coil 33, the tracking control coil 34, and the balancer 31 can increase the damping ratio.

As a result, it is possible to reduce the resonance peak value at the higher resonance frequencies in the focusing direction and the tracking direction of the movable portion, and the light beam spot condensed by the objective lens 30 is deflected on the surface of the information recording medium. , It is possible to improve the stability of the servo that shows the performance of following the eccentricity.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a sectional view of an objective lens actuator showing a second embodiment of the present invention. In FIG. 3, the configuration other than the objective lens holder 36 is the same as that of the first embodiment. The objective lens holder 36 different from the configuration of FIG. 2 is that a recess 37 for accumulating the acrylate resin material 35 between the focusing control coil and the focusing control coil is provided. With this configuration, the uncured portion of the acrylate resin material 35 can be produced more reliably, and the damping effect of the movable portion can be further improved. Further, as a method of curing only the surface of the acrylate resin material 35, an ultraviolet curable acrylate resin material may be used, and by irradiating ultraviolet rays from the outside, it is possible to cure only the range to which the light reaches.

It should be noted that in an objective lens actuator using a 4-wire support system or a leaf spring support system, which is a system for supporting an objective lens holder other than the above-mentioned structure,
If an acrylate resin material is sandwiched between the objective lens holder and the focusing control coil and tracking control coil, and only the surface of the acrylate resin material is cured, and the inside remains uncured, The same effect can be obtained.

[0017]

As described above, according to the present invention, the acrylate resin material for suppressing the vibration is provided between the focusing control coil and the tracking control coil and the objective lens holder, and a part of the acrylate resin material is left uncured. As a result, the damping ratio of the movable portion can be increased, and the resonance peak value of the movable portion at the higher resonance frequencies in the focusing direction and the tracking direction can be suppressed to be low. As a result, it is possible to improve the stability of the servo performance, which shows the performance of making the beam spot focused by the objective lens follow the surface wobbling and eccentricity of the information recording medium, and to prevent external disturbance such as vibration. It is possible to provide an objective lens actuator with excellent seismic resistance that does not impair tracking performance.

[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 sectional view of the objective lens actuator.

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

FIG. 4 is a perspective view of a conventional objective lens actuator.

[Explanation of symbols]

 21 Base 23 Spindle 27 Bearing 28, 36 Objective Lens Holder 30 Objective Lens 31 Balancer 33 Focusing Control Coil 34 Tracking Control Coil 35 Acrylate Resin Material 37 Cavity

Claims (2)

[Claims] 1. An objective lens holding body, comprising: an objective lens holding body for holding an objective lens; and a control coil for driving the objective lens holding body in directions parallel to and perpendicular to an optical axis of an optical system. An objective lens actuator, characterized in that an acrylate resin material is sandwiched between a body and the control coil, only the vicinity of the surface of the acrylate resin material is cured, and the inside is left uncured. 2. The objective lens actuator according to claim 1, wherein a concave portion for accumulating an acrylate resin material is provided on a side surface of an objective lens holder for holding the objective lens.