JPS62154333A - Objective lens driving device - Google Patents

Abstract

PURPOSE:To improve the easiness of assembling of the device and to miniaturize the device by making the direction of magnetizing of permanent magnets the radial direction and arranging them opposite to a coil. CONSTITUTION:Permanent magnets 6a, 6b are positioned by a yoke 8 and joined, and magnetized in radial direction. A lens holder 3 drives an objective lens 1 in the direction of sliding and rotation to a supporting shaft 4 and makes focus control and track control of the objective lens 1. Thus, the positioning of permanent magnets 6a, 6b is made possible by the yoke 8 and assembling is made easy. Further, the efficiency of a magnetic circuit is improved, and the gap magnetic flux density of 1.5 times-2 times is obtained by using the permanent magnets of the same volume, and thereby, the device can be miniaturized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an objective lens driving device, particularly a reproduction device that controls track deviation and defocus of a light spot focused on an information recording surface of an optical disk. The present invention relates to an objective lens driving device for a device or a recording/reproducing device.

[Prior Art] Figures 3 to 5 show a conventional objective lens drive device. In the figures, (1) is an objective lens, (2) is a counterweight, and (3) is a cylindrical bearing. A lens holder (4) having a lens holder (3a) is fitted so that the bearing (3a) of the lens holder (3) is slidable in the axial direction of arrow A in FIG. 8 and rotatable in the direction of arrow S in FIG. attached spindle, (5)
is a support rubber that holds the lens holder (3), (6a),
(6b) is a permanent magnet, (7a), (7b) are yokes, (
8) is a yoke that also serves as a holding stand for the support shaft (4) and permanent magnets (6a) and (6b), (9) is a fixing stand for the support rubber (5),
(10) is a focus control coil, (1' 1 a ), (
11b), (11c), and (11d) are coils for track control; (12a>, (12b) are mounting the support rubber (5) on the fixing base (9) (fixing screws); (13) are the cover;
14) is covered with a coil holder.

Next, the operation will be explained. Focus control coil (10
) by applying a desired current 8 to the lens holder (3).
slides in the direction of arrow A to perform focus control. Also, track control coils (11a), (11b), (11c)
, (11d>), the lens holder (3) rotates in the direction of arrow "3" and is fixed at a position a certain distance away from the support shaft (4). Track control is performed by rotating the objective lens (1).

[Problems to be solved by the invention] Since the conventional objective lens driving device is configured as described above, the permanent magnets (6a) and (6b) 1 and the yoke (7
It is necessary to position and assemble parts a) and (7b), which poses a problem in terms of ease of assembly.

Also, in order to increase the magnetic flux density in the magnetic circuit gap by 1 t, it is necessary to increase the volume of the permanent magnet.
It was difficult to downsize. This invention was made to solve the above-mentioned problems, and aims to improve the assemblability of an objective lens driving device and to reduce its size.

[Means for Solving the Problems] In the objective lens driving device according to the present invention, the permanent magnet is magnetized in the radial direction, and the permanent magnet is arranged opposite to the coil.

[Operation] The configuration of the objective lens driving device according to the present invention facilitates the positioning of the permanent magnet, improves assembly efficiency, and improves the magnetic flux density in the magnetic circuit gap.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1st
The figure is an assembled diagram of an objective lens driving device according to an embodiment of the present invention, and FIG. 2 is a partial assembly diagram showing a permanent magnet part. The same parts as in FIGS. It is attached. (8) is a support shaft (4) and a permanent magnet (6a),
This is a yoke that also serves to hold (6b). Permanent magnet (6a
) and (6b) are positioned and joined by a yoke (8), and are magnetized in the radial direction.

With this configuration, the lens holder (3) is driven in the sliding direction and rotation direction with respect to the support shaft (4), and the objective lens (1)
) performs focus control and track control.

[Effect of the invention] As described above, according to the present invention, the permanent magnet (6a),
(6b) can be positioned by the yoke (8), and the ease of assembly is significantly improved.

In addition, the efficiency of the magnetic circuit is improved, and the same volume of permanent ta
By using stones, the Gillep magnetic flux density can be increased by 1.5 to 2 times by 1.7 times, making it possible to downsize the device. Moreover, cost reduction is possible.

[Brief explanation of drawings]

1 is an exploded perspective view of an objective lens drive device according to an embodiment of the present invention, FIG. 2 is a partially exploded perspective view showing the permanent magnet portion, and FIG. 3 is an exploded perspective view of a conventional objective lens drive device. In the perspective view, FIG. 4 is a sectional view of the assembled state, and FIG. 5 is a partially exploded oblique view, (1) is the objective lens, (3) is the lens holder, and (4) is the support. axis, (10)
(11a) and (11b) are track control coils; (6a) and (6b) are permanent magnets. In addition, in the drawings, the same reference numerals indicate the same or equivalent members. Agent Patent Attorney Masu Oiwa Kl [(2 others) Figure 1 Figure 3 Figure 4. ! 1

Claims (1)

[Claims] (1) A lens holder that is rotatably and axially movably fitted onto a support shaft and holds a lens having an optical axis parallel to the axial direction of the support shaft; In an objective lens drive device, the objective lens drive device includes a drive device that drives in an axial direction, and drives the lens holder to control track deviation and defocus of a light spot focused on a disk via the lens, The drive device performs track control and focus control by arranging a coil in a magnetic path made up of a yoke and an arc-shaped permanent magnet magnetized in the radial direction, and passing a desired current through the coil. An objective lens drive device featuring: