JPS6112596Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical system driving device, and more particularly to a driving device for driving an optical system for irradiating a recording surface of a recording medium (disk) with spot light in an information reading device.

Figures 1 and 2 are patent applications filed by the applicant in 1982.
The structure of the optical system drive device in the information reading device proposed in No. 161565 is shown. Figure 1 is a side sectional view taken along a plane passing through the central axis of the pickup, and Figure 2 is a side sectional view taken from the surface facing the disk. It is a front view. In the figure, reference numeral 1 denotes a pickup with a built-in semiconductor laser (not shown), which emits light from the laser onto a disk (recording medium) 2.
converge on the recording surface. Around the pick-up 1, there are, for example, four pieces for driving the pick-up 1 in the focus direction (that is, the direction perpendicular to the disk 2), the tracking direction (that is, the radial direction of the disk 2), and the tangential direction (that is, the direction tangential to the track of the disk 2). The drive mechanism section 3a,
3b, 3c and 3d are arranged. The pick-up 1 is arranged in the central hole 4 of the holding member 4 so as to be located equidistantly from the drive mechanism parts 3a, 3b, 3c and 3d.
It is fitted in b.

In the drive mechanism parts 3a to 3d, respectively,
A magnetic circuit 9 is formed by a yoke 6 fixed to a base 5, a magnet 7 erected on the yoke 6, and a pole piece 8 fixed to the upper surface of the magnet 7. The bobbin 1 is fixed to the lower surface of the arm portion 4a of the holding member 4 via the holding member 10.
1 and the drive coil 1 wound around the bobbin 11
2 is positioned within the gap of the magnetic circuit 9. The mounting member 10 is fixed to a ring 14 provided on the upper surface of the yoke 6 via a damper 13. The positional relationship of these drive mechanism parts 3a to 3d is as follows:
The drive mechanism section 3 is aligned so that the track direction shown by arrow 15 in FIG.
b and 3d are arranged so that the lines connecting the centers thereof coincide with each other, or the lines connecting the track direction and the centers of the drive mechanism parts 3a and 3b and the lines connecting the drive mechanism parts 3c and 3d are parallel to each other. It is located.

In the optical system drive device having such a configuration, since the magnetic circuit 9 is configured for each drive mechanism section 3a to 3d, there are disadvantages in that the number of parts is large and the number of assembly steps is increased. Further, the magnetic circuit 9 is of a so-called internal magnetic type, and the internal magnetic type generally has the drawback of high cost due to the use of expensive alnico magnets.

An object of the present invention is to provide an optical system drive device that enables a reduction in the number of parts and cost.

The optical system drive device according to the present invention includes a yoke having a central hole in which an optical system is located, a plurality of protrusions provided around the central hole, and a yoke that is magnetized in the thickness direction and has a diameter larger than the outer diameter of the protrusions. A magnetic circuit is constituted by a plate-shaped magnet placed on a yoke and having a plurality of holes with a diameter of However, the present invention is characterized in that a plurality of coils attached to an optical system are positioned within a gap between the peripheral wall of the plurality of protrusions and the plate.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 3 is a cross-sectional view of an embodiment of the optical system driving device according to the present invention, in which parts equivalent to those in FIG. 1 are designated by the same reference numerals. In the figure, the configuration other than the magnetic circuit 90 is completely the same as in FIG. As shown in a perspective view before assembly in FIG. 4, the magnetic circuit 90 includes a center hole 91 in which a pickup 1 as an optical system is located, and four protrusions 92a to 92d provided around the center hole. Yoke with 9
3, and protrusions 92a to 9 that are magnetized in the thickness direction.
Four holes 94a to 94 with a diameter larger than the outer diameter of 2d
a plate-shaped magnet 96 having a center hole 95 and a plate-shaped magnet 96 placed on the yoke 93;
6 and a plate 99 which has holes 97a to 97d whose diameters are substantially the same as or slightly smaller than those of the holes 94a to 94d, and a center hole 98, and which is placed on the magnet 96. The magnetic circuit 90 is of a so-called external magnetic type, and a low-cost ferrite magnet or the like is used as the magnet. Further, the external magnetic type magnetic circuit has the advantage that the height of the magnetic circuit can be reduced and there is no demagnetization due to large input.

The yoke 93 in the magnetic circuit 90 having such a configuration
Four drive coils 12 attached to the pickup 1 via the holding member 4 are positioned in the gaps between the peripheral walls of the protrusions 92a to 92d and the inner walls of the holes 97a to 97d of the plate 99. . By appropriately combining the drive signals applied to these four drive coils 12, the pickup 1 can be vibrated in the focusing direction, tracking direction, and tangential direction.

In the above embodiment, a configuration using four drive mechanism sections has been described, but it goes without saying that the configuration can also be applied to, for example, three drive mechanism sections. Further, the optical system driven by the present driving device is not limited to a semiconductor laser pickup, and may be only an objective lens or only a part of an optical system.

As described in detail above, according to the present invention, the magnetic circuits of the plurality of drive mechanism parts are integrally configured, which makes it possible to significantly reduce the number of parts, and makes assembly very easy. The drive mechanism section can be positioned easily and reliably.
Furthermore, by using an inexpensive ferrite magnet, costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an example of a conventional optical system drive device, FIG. 2 is a front view seen from the disk facing surface of FIG. 1, and FIG. 3 is a cross section of an example of an optical system drive device according to the present invention. 4 is a perspective view of the magnetic circuit in FIG. 3 before assembly. Explanation of the symbols of the main parts, 1... Pick up,
3a to 3d... Drive mechanism section, 6, 93... Yoke, 7, 96... Magnet, 9, 90... Magnetic circuit, 12... Drive coil.

Claims (1)

[Claims for Utility Model Registration] (1) A driving device for driving an optical system for irradiating a recording surface of a recording medium with spot light,
a yoke having a central hole in which the optical system is located and a plurality of protrusions provided around the central hole; a plurality of holes magnetized in the thickness direction and having a diameter larger than the outer diameter of the protrusions; A plate-shaped magnet having a center hole in which an optical system is located and placed on the yoke, a plate having substantially the same shape as the magnet and placed on the magnet, and the plurality of protrusions. and a plurality of coils attached to the optical system so as to be located in a gap between the peripheral wall of the optical system and the plate. (2) The optical system driving device according to claim 1, wherein the magnet is a ferrite magnet.