JPH052756A - Optical head driving mechanism - Google Patents

Abstract

PURPOSE:To sharply make a movable part light in weight, and to attain a high speed seek by holding the holding body of an objective lens and a coil by a parallel link mechanism, and providing the holding body at a guide rail so as to be capable of sliding. CONSTITUTION:An objective lens 3 is fixed and held by a holding body 4, and a focusing coil 5 and a tracking coil 6 are attached to the holding body 4. A wall 4a of this holding body 4 is allowed to come in touch with a guide rail 11 so as to be capable of sliding on a face including both a tracking direction and a focusing direction. Then, the objective lens holding body 4 is held by the parallel link mechanism formed of both a link rod 7 and a link stand 8, and the lens holding body 4 is moved to the tracking direction and the focusing direction while the direction of an optical axis is held. And also, the guide rail 11 is serving also as the yoke of a driving magnetic circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive mechanism for an optical head in an optical information recording / reproducing apparatus such as an optical disk device, and more particularly to a drive mechanism having a lightweight movable part and suitable for high speed drive.

[0002]

2. Description of the Related Art In an optical disk device, in order to perform a seek operation for accessing a desired information track of an optical disk at a high speed, the optical head is movable in order to perform a seek operation at high speed. It is effective to move the movable part with a large acceleration by reducing the weight of the part.

By the way, a conventional optical head is provided with a drive mechanism for supporting a carriage so as to be capable of reciprocating in a tracking direction for a seek operation. Further, for the tracking operation and the focusing operation, the objective lens of the light beam irradiation optical system is held by a holder, and the holder is supported so as to be movable with respect to the carriage in the tracking direction and the focusing direction, and a driving mechanism for them Is equipped with.

As described above, in the conventional optical head, the means for both the relative movement between the objective lens holder and the carriage and the relative movement between the carriage and the head body in the tracking direction are movable parts. Because it is provided in
There is a limit to weight reduction.

In view of the above-mentioned problems of the prior art, it is an object of the present invention to provide a drive mechanism for an optical head which can greatly reduce the weight of the movable part of the optical head and can perform a high-speed seek operation. To do.

[0006]

According to the present invention, in order to achieve the above object, both a focusing coil and a tracking coil are provided with respect to an objective lens for converging and irradiating a light beam onto an optical information recording medium. The movable body is fixedly arranged to form a movable body, and the movable body is slidably contacted with a guide member on a surface including both the tracking direction and the focusing direction, and the movable body is further provided with the objective lens. An optical head drive mechanism is provided, which is supported by a parallel link mechanism capable of moving the movable body in the tracking direction and the focusing direction while maintaining the optical axis direction of.

In the present invention, as the guide member, a yoke forming a magnetic circuit for generating a magnetic field acting on the focusing coil and / or the tracking coil can be used.

Further, in the present invention, a wire may be used for the parallel link mechanism, and an extension force may be applied to the wire.

[0009]

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

FIG. 1 is a perspective view for explaining the structure of a first embodiment of an optical head driving mechanism according to the present invention, and FIG.
Is a plan view thereof.

In these figures, the objective lens 3 is fixedly held by a holder 4, and a focusing coil 5 and a tracking coil 6 are attached to the holder. By these, the movable body of the present invention is formed. The objective lens holder 4 can reciprocate in the tracking direction along two guide rails 11 in the tracking direction. That is, the objective lens holder 4 is formed with two vertical walls 4 a, and each wall is in sliding contact with the inner side surface of each guide rail 11. However, the inner surface of the guide rail is a surface including the optical axis direction (focusing direction) of the objective lens 3 and the tracking direction, and the wall 4a is higher than the height of the guide rail 11, so that the objective lens support 4 is The wall 4a is movable in the focusing direction with respect to the guide rail 11 while maintaining the sliding contact with the guide rail 11.

On the other hand, the objective lens holder 4 is supported by two parallel link mechanisms which are symmetrical with respect to the tracking direction. Reference numeral 7 is a rod that constitutes the link mechanism. One end of each rod is attached to the objective lens holder 4, and the other end is attached to the link base 8. Both ends of these rods are attached so as to be rotatable in the vertical direction. In each link mechanism, the link base 8
Is provided with a bearing portion 8a in a direction orthogonal to the inner surface of the guide rail 11, and a shaft 9 fixed to the head body is slidably inserted in the bearing portion 8a. Reference numeral 10 is a pin for locking the link base 8 so as not to rotate around the shaft 9, and is fixed to the head body side. Also,
Reference numeral 14 is a mirror for deflecting the light beam from the light source in the optical axis direction of the objective lens 3.

FIG. 2 shows the relationship between the head and the optical disk. Reference numeral 2 is an optical disk, and 1 is a turntable for supporting the optical disk. In addition, in FIG.
Is a magnet, and the magnet is attached inside the outer yoke 13. The guide rail 11 also functions as an inner yoke, and the outer yoke 1 is attached to both ends of the inner yoke.
Both ends of 3 are connected. A magnetic circuit is formed by the magnet 12, the inner yoke 11 and the outer yoke 13, and the focusing coil 5 and the tracking coil 6 are partially located in the magnetic field formed between the magnet 12 and the inner yoke 11.

Therefore, when a focusing control current is passed through the focusing coil 5, the objective lens holder 4 is moved to the wall 4
a is guided while sliding on the inner surface of the guide rail 11 and moves to a desired position in the focusing direction. Since the movement distance in the focusing direction is small, the link rod 7 can follow this movement by elastic deformation. When a tracking control current is passed through the tracking coil 6,
The wall 4a of the objective lens holder 4 is guided while sliding on the inner surface of the guide rail 11, and moves to a desired position in the tracking direction. During the movement in the tracking direction, the bearing portion 8a of the link base 8 appropriately moves in the longitudinal direction with respect to the shaft 9. It should be noted that this movement slightly appears even when moving in the focusing direction.

As described above, in the present embodiment, the movable parts are limited to the objective lens 3, the holder 4 thereof, and its accessories. The link rod 7 rotates with respect to the link base 8 and the link base 8 moves in the direction of the axis 8 of the link base 7,
Since the moving distance is small, the effective mass when moving the objective lens holder 4 is small. Therefore, in this embodiment, since the movable portion is lightweight, it is possible to drive the movable portion at high speed in the tracking direction.

Further, in this embodiment, since the guide member is also used as the yoke of the driving magnetic circuit, the number of parts is small.

FIG. 3 is a perspective view for explaining the configuration of the second embodiment of the optical head drive mechanism according to the present invention, and FIG.
Is a plan view thereof. In these figures, the same members as those in FIGS. 1 and 2 are designated by the same reference numerals.

In this embodiment, a wire 17 such as a tungsten wire is used instead of the rod 7 in the first embodiment.
Is used. The shaft 9 fixed to the head body side extends through the bearing portion 8a toward the inside, and the compression coil spring 15 is wound around this portion, and the inner end of the spring is on the head body side. The outer end pushes the link base 8 outward with an appropriate force. Therefore,
An extension force is always acting on the wire 17.

This embodiment also has an operation similar to that of the first embodiment. Further, in the present embodiment, since the wire is used, further weight reduction can be achieved, and there is an advantage that the wire does not have elasticity in the compression direction and thus vibration is hardly generated.

[0020]

As described above, according to the present invention, both the focusing coil and the tracking coil are fixedly arranged with respect to the objective lens to form a movable body, and the movable body is set in the tracking direction with respect to the guide member. Since the movable body is slidably contacted on the surface including both the focusing direction and the movable body and is supported by the parallel link mechanism, the movable portion can be remarkably reduced in weight and high-speed seek operation can be performed.

[Brief description of drawings]

FIG. 1 is a perspective view for explaining the configuration of a first embodiment of an optical head drive mechanism according to the present invention.

2 is a plan view of the optical head drive mechanism of FIG. 1. FIG.

FIG. 3 is a perspective view for explaining the configuration of a second embodiment of the optical head drive mechanism according to the present invention.

4 is a plan view of the optical head drive mechanism of FIG.

[Explanation of symbols]

1 turntable 2 optical disc 3 Objective lens 4 Objective lens holder 4a wall 5 Focusing coil 6 Tracking coil 7 rod 8 link stand 8a Bearing part 9 axes 10 pin 11 Inner yoke (guide rail) 12 magnets 13 Outer yoke 14 mirror 15 coil spring 17 wires

Claims (3)

[Claims] 1. A focusing member and a tracking coil are fixedly arranged with respect to an objective lens for converging and irradiating a light beam onto an optical information recording medium to form a movable member, and the movable member is a guide member. Is slidably contacted with a surface including both the tracking direction and the focusing direction, and the movable body is moved in the tracking direction and the focusing direction while maintaining the optical axis direction of the objective lens. An optical head drive mechanism, which is supported by a parallel link mechanism that can be moved. 2. The optical head drive mechanism according to claim 1, wherein the guide member is a yoke forming a magnetic circuit for generating a magnetic field acting on the focusing coil and / or the tracking coil. 3. The optical head drive mechanism according to claim 1, wherein the parallel link mechanism uses a wire, and means for applying an extension force to the wire is provided.