JPH052758A - Optical head driving mechanism - Google Patents

Abstract

PURPOSE:To make a movable part light in weight and to attain an exact tracking operation and seek operation by abutting the projecting part and inside face part of a carriage to an inner yoke and an outside yoke, and controlling the movement direction of the carriage. CONSTITUTION:A focusing coil 5 is fixed to a holding body 4 of an objective lens 6, and the objective lens holding body 4 is attached to a carriage 1 so as to be movable to a focusing direction by a parallel plate spring 3. Then, a tracking coil 2 is fixed to the carriage 1, and at the time of the movement of the carriage 1 to a tracking direction, projecting parts 1a, 1b, 1c, and 1d of the carriage 1 are abutted to two inside yokes 7 of a driving magnetic circuit in order to control the movement direction of the carriage 1 to a horizontal direction orthogonally crossing the tracking direction. On the other hand, inside face parts 1e, 1f and 1g of the carriage 1 are abutted to two outside yokes 9 of the driving magnetic circuit in order to control the movement direction of the carriage 1 to the focusing direction.

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 particularly to a lightweight drive mechanism which enables accurate tracking and seek operations. Regarding

[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.

Therefore, the objective lens holder is supported so as to be movable with respect to the carriage only in the focusing direction, and the movement in the tracking direction (tracking and seek) is performed only by moving the carriage, thereby simplifying the driving mechanism. It may be possible to reduce the weight. A sliding guide is generally used as the guide for moving the carriage. In a conventional sliding guide, a round bar guide main shaft and a round bar auxiliary shaft for preventing rotation of the carriage around the main shaft are arranged in parallel, and a carriage is slidably engaged with these two shafts. Become. However, in this guide, the center of the main axis is off the center of the carriage,
Imbalance tends to occur when moving the carriage. Therefore, it is difficult to maintain high control accuracy of the movement in the tracking direction.

In view of the above problems of the prior art, the present invention can reduce the weight of the movable portion of the optical head.
Moreover, it is an object of the present invention to provide a drive mechanism for an optical head that can accurately perform a tracking operation and a seek operation.

[0007]

According to the present invention, in order to achieve the above object, a tracking coil is arranged on a carriage that supports an objective lens for converging and irradiating a light beam onto an optical information recording medium. The carriage is attached to the guide means so as to be capable of reciprocating in the tracking direction, and has a drive magnetic circuit for generating a magnetic flux that crosses the tracking coil. The magnetic circuit has two magnetic circuits in the tracking direction. An inner yoke and two outer yokes in the tracking direction are included, and the inner yoke and the outer yoke constitute the guide means, and only the two inner yokes move the carriage in the tracking direction and the optical axis direction of the objective lens. The carriage is regulated in a first direction perpendicular to a plane including both, and at least the two outer yokes move the carriage to the objective lens. Characterized in that it is restricted to a second direction of the optical axis, the optical head driving mechanism, is provided.

In the present invention, the regulation of the carriage by the inner yoke in the first direction can be performed at two different positions in the tracking direction.

Further, in the present invention, the regulation of the carriage in the second direction by the outer yoke is made at two different positions in the tracking direction, and at one of the positions, the carriage abuts against the two outer yokes. The carriage can be brought into contact with only one yoke at the other position.

Further, the carriage is regulated in the second direction at two different positions in the tracking direction, and at one of the positions, the carriage is brought into contact with two outer yokes to regulate in the second direction. None, and at the other position, the carriage can be brought into contact with the two inner yokes to regulate in the second direction.

[0011]

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

FIG. 1 is a plan view for explaining the configuration of a first embodiment of an optical head driving mechanism according to the present invention, and FIGS. 2, 3, 4, and 5 are A- of FIG. 1, respectively. It is an A sectional view, a BB sectional view, a CC sectional view, and a DD sectional view.

In these figures, the objective lens 6 is held by a holding body 4, to which a focusing coil 5 is attached. The objective lens holder 4 is attached to the carriage 1 by a parallel leaf spring 3 so that the objective lens holder 4 can move in parallel in the substantially focus direction. A tracking coil 2 is attached to the carriage 1. The carriage 1 is supported by two rod-shaped inner yokes 7 arranged in parallel so as to be slidable in the longitudinal direction (tracking direction) of the yokes. Each inner yoke 7 constitutes a drive magnetic circuit together with the relay yoke 13, the outer yoke 9 and the magnet 8. The two inner yokes 7 are positioned by spacers 11 and 12, and the positioning is performed by a pressing force of a holding leaf spring 10 arranged between the base 15 and the outer yoke 9. The leaf spring is fixed to the base 15 by the screw 16 after the inner yoke is positioned by the pressing force, and thus the magnetic circuit is fixed to the base 15. The spacer 1
Both 1 and 12 are in the shape of a round bar, and it is possible to have a high accuracy of the outer diameter, and it is possible to maintain the distance between the inner yokes 7 with a high accuracy. In addition, the spacer 11 is provided with a hole at the center through which a recording or reproducing laser beam passes.

In FIG. 2, 14 is a mirror for deflecting a light beam arriving in the horizontal direction from the light source side in the vertical direction (the optical axis direction of the objective lens).

As shown in FIGS. 1, 4 and 5, the carriage 1 is guided by the projections 1a, 1b, 1c, 1d of the carriage 1 so as to be brought into contact with the inner surface of the inner yoke 7 and guided in the horizontal direction. Of the inner surface portion 1e, 1f, 1 of the inner surface portion 1e, 1f, 1
The outer yoke 9 is brought into contact with the upper and lower surfaces of the outer yoke 9 by g to be guided and its vertical movement is restricted. As shown in FIG. 5, the inner surface portion 1h of the carriage 1 escapes so as not to contact the outer yoke 9. This is because even if the shape accuracy of the carriage 1 is slightly defective, the carriage 1 can be dealt with favorably during movement in the tracking direction.

Next, the operation of this embodiment will be described. When the tracking coil 2 is energized via a flexible cable (not shown), a current flows in a direction orthogonal to a horizontal magnetic field generated by a magnetic circuit composed of the inner yoke 7, the magnet 8, the outer yoke 9 and the relay yoke 13. The tracking coil 2 receives a force in the longitudinal direction of the inner yoke 7, and thereby the carriage 1 is driven in the tracking direction. At this time, in the carriage 1, the protrusions 1a, 1b, 1c, 1d are brought into contact with the inner yoke 7 and guided, and the horizontal movement is restricted, and the inner surface portions 1e, 1f, 1g are guided by the outer yoke 9. The vertical movement is restricted. When the focusing coil 5 is energized, a current flows in a direction orthogonal to the horizontal magnetic field, the focusing coil 5 receives a vertical force, and the objective lens portion supported by the parallel leaf spring 3 moves vertically. To do.

FIG. 6 is a plan view for explaining the configuration of the second embodiment of the optical head drive mechanism according to the present invention, and FIG.
FIG. 6 is a sectional view taken along line EE. In these drawings, the same members as those in FIGS. 1 to 5 are designated by the same reference numerals. The sectional view taken along the line AA, the sectional view taken along the line BB, and the sectional view taken along the line CC of FIG. 6 are the same as those shown in FIGS. 2, 3, and 4, respectively.

In this embodiment, the portions of the carriage 1 on which the projections 1c and 1d are formed do not extend to the outer yoke 9, and the inner surface portions 1g and 1h thereof contact the upper and lower surfaces of the inner yoke 7. There is. Since the distance between the two inner yokes 7 is shorter than the distance between the two outer yokes 9, the two inner surface portions 1g and 1h in contact with the inner yoke 7 have some defects in the shape accuracy of the carriage 1. Can also be absorbed, with the same effect as if a relief is formed on one side.

In this embodiment, the protrusion 1 of the carriage 1
The portion where a and 1b are formed extends to the outer yoke 9, but the base of this portion is made wider to improve rigidity as compared with the first embodiment. Also, the carriage 1
Since the portion where the protrusions 1c and 1d are formed is short,
At this point, the increase in carriage weight due to the widened roots on the side of the protrusions 1a and 1b is offset.

[0020]

As described above, according to the present invention, since the carriage is restricted in the first direction by the two inner yokes of the driving magnetic circuit, the rattling occurs when the carriage slides. In addition, since the carriage is regulated in the second direction with a wide width by using the two outer yokes of the driving magnetic circuit, the occurrence of tilt when the carriage slides is small, and thus only the movement of the carriage is performed. Even if the driving in the tracking direction is performed, the control accuracy can be maintained high, and both weight reduction and accuracy of the tracking operation and the seek operation can be realized.

[Brief description of drawings]

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

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG.

FIG. 4 is a sectional view taken along line CC of FIG.

5 is a sectional view taken along line DD of FIG.

FIG. 6 is a plan view for explaining the configuration of the second embodiment of the optical head drive mechanism according to the present invention.

7 is a cross-sectional view taken along line EE of FIG.

[Explanation of symbols]

1 carriage 2 tracking coil 3 leaf spring 4 Objective lens holder 5 Focusing coil 6 Objective lens 7 Inner yoke 8 magnets 9 Outer yoke 10 leaf spring 11 Spacer 12 spacers 13 Relay yoke 14 mirror 15 bases

Claims (4)

[Claims] 1. A tracking coil is arranged on a carriage that supports an objective lens for converging and irradiating a light beam onto an optical information recording medium, and the tracking coil is attached to a guide means so that the carriage can reciprocate in a tracking direction. And a driving magnetic circuit for generating a magnetic flux that crosses the tracking coil, the magnetic circuit including two inner yokes in the tracking direction and two outer yokes in the tracking direction. A yoke and an outer yoke constitute the guide means, and only the two inner yokes restrict the carriage in a first direction perpendicular to a plane including both the tracking direction and the objective lens optical axis direction. An optical head, wherein the two outer yokes restrict the carriage in a second direction of the objective lens optical axis direction. Drive mechanism. 2. The optical head drive mechanism according to claim 1, wherein the inner yoke restricts the carriage in the first direction at two different positions in the tracking direction. 3. The regulation of the carriage in the second direction by the outer yoke is made at two different positions in the tracking direction, and the carriage is in contact with the two outer yokes at one of the positions. The optical head drive mechanism according to claim 1, wherein the carriage is in contact with only one yoke at the other position. 4. The regulation of the carriage in the second direction is performed at two different positions with respect to the tracking direction, and at one of the positions, the carriage comes into contact with two outer yokes to regulate in the second direction. The optical head drive mechanism according to claim 1, wherein the carriage is brought into contact with the two inner yokes at the other position to regulate the carriage in the second direction.