JPH05258326A - Objective lens driving device - Google Patents

Abstract

PURPOSE:To provide an objective lens driving device with an excellent servo characteristic by solving the problems of the occurence of rolling due to the deviation between the centroid of a movable part and a driving center and the occurence of rolling due to an inclination at the time of mounting a tracking coil and the positional deviation of a magnet in the objective lens driving device of an optical pickup used for an optical disk device and a hologram device, etc. CONSTITUTION:A balancer 17 with a balance position adjustable is provided on a side opposing to the objective lens 1 of a U-shaped objective lens holder 2 and two pairs of tracking coils 7 are inclined respectively so as to cancel mutually driving force to a focusing direction due to inclination. Further, opposing magnetic circuits are deviated in symmetry and in an opposite phase to the driving center. Thus the occurence of rolling due to the dispersion of a component precision and the dispersion of a fitting precision is suppressed and the objective lens driving device with an excellent servo characteristic is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens driving device for adjusting the irradiation position of a light beam by changing the position of the objective lens in an optical pickup used for an optical disk device, a hologram device or the like.

[0002]

2. Description of the Related Art An optical disc apparatus is for performing recording / reproducing by selecting an arbitrary track by moving the entire optical pickup in a tracking direction of a rotating optical disc (radial direction of the disc). Has an objective lens driving device for subtly displacing the objective lens to adjust the irradiation position of the light beam. This objective lens driving device adjusts the focus of the light beam by displacing the objective lens in the optical axis direction, and also adjusts the tracking by displacing the objective lens in the tracking direction on a plane orthogonal to the optical axis. Is also done.

This conventional objective lens driving device will be described with reference to FIGS. According to the drawings, 1 is an objective lens of an optical system whose periphery is fixed and held by an objective lens holder 2. In addition to the objective lens 1 and the objective lens holder 2, a focus coil 6, a tracking coil 7 and a balancer described later are provided. A movable portion of the drive device is constituted by 17 and. This movable portion is supported by the substrate 4 via the movable portion supporting member 3 and the support pins 5. The substrate 4 is attached to the tip of an optical pickup main body (not shown), and irradiates the optical disk with a light beam through the objective lens 1.

The movable portion supporting member 3 for supporting the movable portion on the substrate 4 is formed by integrally molding resin or by integrally molding resin and metal by an insert molding method or the like. As shown in FIG. The movable portion support portion 10 includes an intermediate support portion 12, a connecting portion 13, a column portion 15, and a support hole 16. The movable portion support portion 10 fixed near the center of the objective lens holder 2 is
It is coupled to the intermediate support portion 12 via the tracking hinge portion 11. The tracking hinge portion 11 is a resin constriction portion formed long in the focus direction (Z direction), and the movable portion support portion 10 side can swing on a plane (XY plane) orthogonal to the focus direction. It has such flexibility.

The connecting portion 13 is arranged so as to connect the intermediate supporting portion 12 and the supporting column portion 15 with each other in the vertical direction. Further, the connecting portion 13 and the column portion 15 are connected to each other via a focus hinge portion 14. The focus hinge portion 14 is a resin constriction portion formed long in the tracking direction (X direction),
Each connecting portion is a plane (X-Z) orthogonal to the tracking direction.
It has flexibility so that it can swing on a flat surface. Therefore, the intermediate support portion 12, the connection portion 13, and the support portion 15
Of the focusing hinge portion 14 constitutes a parallel link mechanism. The column 15 is in the optical axis direction (Z direction)
A support hole 16 is formed in the base plate 4, and this hole is inserted into and fixed to the support pin 5 which is erected on the substrate 4. This focus direction coincides with the optical axis direction of the objective lens 1, and the tracking direction coincides with the radial direction of the optical disc (not shown) which irradiates the light beam through the objective lens 1.

The movable part support member 3 thus constructed is
As shown in FIG. 8B, the tracking hinge portion 11
The movable portion support portion 10 can swing with respect to the intermediate support portion 12 with the fulcrum as a fulcrum. Further, as shown in FIG. 8C, by the parallel link mechanism connected by the focus hinge portion 14,
The movable portion support portion 10 and the intermediate support portion 1 with respect to the column portion 15.
2 can be moved in parallel.

Next, the operation of the objective lens driving device will be described. When the tracking coil 7 is appropriately energized, the objective lens driving device uses the tracking hinge portion 11 of the movable portion support member 3 as a fulcrum to hold the objective lens holder. Two
Oscillates in the tracking direction (X direction). Therefore, it is possible to adjust the tracking of the light beam applied to the optical disc through the objective lens 1. When the focus coil 6 is appropriately energized, the movable portion support member 3
The objective lens holder 2 is moved in parallel in the focus direction (Z direction) by the parallel link mechanism connected by the focus hinge portion 14. Therefore, the focus of the light beam with which the optical disc is irradiated through the objective lens 1 can be adjusted.

The objective lens holder 2 and the movable portion supporting member 3 are mounted by attaching the movable portion supporting member 10 to the U-shaped objective lens holder 2 and then mounting the balancer 17 between the connecting portions 13 formed vertically. And mount it on the side of the movable part support 3 facing the objective lens 1. In this way, the center of gravity of the movable portion including the objective lens 1, the objective lens holder 2, and the tracking coil 7 and the center of gravity of the tracking hinge portion 11 are arranged so as to coincide with each other.

[0009]

However, in the above-mentioned conventional configuration, the center of gravity of the movable part and the drive center do not match due to variations in the mass of the movable part components and mounting positions, and the servo characteristics become unstable due to rolling. In addition, when the mounting of the tracking coil 7 on the side surface of the movable portion is inclined by θ (on the YZ plane), a driving force f in the focus direction is generated when the tracking coil 7 is energized, and the tracking coil 7 is centered on the Y axis. When the rotational driving force is generated or the left and right magnetic circuits are deviated, rolling occurs similarly to the above, and
There is a problem that the characteristics of the body become unstable.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an objective lens driving device which is less likely to cause rolling and has excellent servo characteristics.

[0011]

In order to solve this problem, the objective lens driving device of the present invention has a balance adjusting mechanism in the balancer mounting portion or the balancer main body.

[0012]

With the above construction, the influence of the mass of the movable part components and the variation of the mounting position can be eliminated, and the center of gravity of the movable part and the drive center can be accurately matched, so that the occurrence of rolling can be suppressed and stable servo characteristics can be obtained. It is what is done.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the objective lens driving device of the present invention will be described below with reference to FIGS.

The same parts as those of the prior art will be designated by the same reference numerals and the description thereof will be omitted. As shown in the figure, the U-shaped objective lens holder 2 holds the objective lens 1 on one end side in the direction (Y direction) orthogonal to the tracking direction, but on the other end side of the U-shaped tip. A balancer 17 whose balance position can be adjusted depending on the position where the screw is woven is provided. By adjusting the position of the balancer 17, the position of the center of gravity of the movable portion and the center of the tracking hinge portion 11 are aligned with each other. Focus coils 6 are provided in the recesses on both ends of the objective lens holder 2 in the tracking direction (X direction), and two pairs of tracking coils 7 are not required on the side surface formed by the focus coils 6 and the objective lens holder 2. In order to cancel the driving force in different directions, the side surfaces are arranged in advance with the opposite inclinations of + θa ′ and −θa ′, respectively. A yoke portion 9 a is provided on the substrate 4 inside the focus coil 6 with a gap from the focus coil 6. In the tracking direction, the magnet 8 is arranged with a gap from the drive coil composed of the focus coil 6 and the tracking coil 7.
The magnets 8 are provided upright from both ends of the substrate 4 so as to be symmetric with respect to the position of the center of gravity of the movable part (the drive center of the tracking hinge part 11) and both ends are + d, respectively so as to have opposite phases in the Y direction.
It is supported by a yoke portion 9b that is displaced by −d, and forms a magnetic circuit together with the yoke portion 9a.

In the above structure, when the focus coil 6 is energized, an electromagnetic force in the focus direction (Z direction) is generated, and this force is generated at the position of the center of gravity of the movable portion. As a result, the movable portion is moved in parallel in the focus direction (Z direction) via the parallel link mechanism of the movable portion support member 3, and the focus adjustment of the light beam on the optical disk can be performed through the objective lens 1. Further, when the tracking coil 7 is energized, an electromagnetic force in the tracking direction (X direction) is generated, and this force acts as a corner force centered on the tracking hinge portion 11 and acts on the movable portion. As a result, the objective lens 1 swings in the tracking direction (X direction), and the tracking direction of the light beam can be adjusted.

As described above, in the above embodiment, by adjusting the positions of the paired balancers 17, the center of gravity of the movable portion and the driving center of the tracking hinge portion 11 are irrespective of variations in the components of the movable portion. Can be matched, and the rolling occurrence of the movable part can be suppressed. Also,
By tilting each of the four tracking coils 7 on the YZ plane so as to cancel the driving force in an unnecessary direction, the X of the movable part due to the tracking coil tilting.
Rolling on the -Z plane can also be suppressed.

Further, by arranging the facing magnets symmetrically with respect to the driving center of the tracking hinge portion 11 and having an opposite phase in the Y direction, rolling of the movable portion on the YZ plane due to variations in the mounting position of the magnets. Can be suppressed.

In this embodiment, the movable portion support portion 3
Is a resin integrally molded hinge, but wires provided in parallel may be used. Further, in the present embodiment, the magnet 8 is attached to the yoke 9a standing upright from the substrate, but the magnet may be attached to the movable portion and the focus coil 6 and the tracking coil 7 may be attached to the yoke 9a.

[0019]

As described above, according to the present invention, by providing the balancer capable of adjusting the position of the center of gravity of the movable part, the position of the center of gravity of the drive center and the position of the center of gravity of the movable part due to the variation in the weight of the components of the movable part and the variation in the mounting position. Since the deviation can be corrected, rolling can be suppressed, and an objective lens driving device having excellent servo characteristics can be realized.

[Brief description of drawings]

FIG. 1 is a plan view of an objective lens driving device according to an embodiment of the present invention.

FIG. 2 is a side view of the same.

FIG. 3 is a side view of a main part for explaining a mounting state of the tracking coil which is the main part.

FIG. 4 is a plan view of a conventional objective lens driving device.

FIG. 5 is a side view of the same.

FIG. 6 is a perspective view of a movable support member, which is a main part of the same.

FIG. 7 is a plan view of the movable part.

8A to 8C are side views for explaining an operating state of the movable support member.

FIG. 9 is a side view of a main part for explaining a rolling state by the tracking coil which is the main part.

[Explanation of symbols]

 1 Objective Lens 2 Objective Lens Holder 3 Movable Support Member 6 Focus Coil 7 Tracking Coil 17 Balancer

Claims (3)

[Claims] 1. An objective lens on at least an upper surface, an objective lens holder having magnets or coils on both side surfaces, a balancer capable of balance adjustment, and a movable part for enabling the objective lens holder to operate in a focus direction and a tracking direction. An objective lens driving device comprising a support member and a magnetic circuit having a coil or a magnet provided so as to face the magnet or the coil. 2. An objective lens holder having an objective lens on at least an upper surface, an electromagnetic circuit including a magnet, a focus coil, and a pair of tracking coils on both side surfaces, and the objective lens holder operable in a focus direction and a tracking direction. An objective lens driving device comprising a movable portion supporting member for supporting, and a pair of the tracking coils being tilted in opposite directions so as to prevent rolling of the objective lens holder. 3. The objective lens driving device according to claim 2, wherein the magnetic circuits on the side surfaces are arranged so as to be shifted in anti-phase symmetry in the front-rear direction from the driving center.