JPS6120663Y2 - - 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 opposite surface of the disk. FIG. In the figure, reference numeral 1 denotes a pickup incorporating, for example, a semiconductor laser (not shown), and converges irradiated light from the laser onto the recording surface of a disk (recording medium) 2. Around the pick-up 1, there are directions for moving the pick-up 1 in the focusing 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).
For example, four drive mechanism parts 3a, 3 are used to drive the
b, 3c and 3d are arranged. The pick-up 1 is inserted into the central hole 4b of the holding member 4 so as to be located equidistantly from the drive mechanism parts 3a, 3b, 3c and 3d.
is attached to.

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.

The optical system driving device having such a configuration is driven in the radial direction of the disk 1 by means not shown in order to follow the track of the disk 1, but in order to facilitate this driving, it is necessary to make the device smaller and lighter. desired.

An object of the present invention is to provide an optical system drive device that can be made smaller and lighter.

The optical system drive device according to the present invention includes at least one pair of drive systems provided so that the optical system is located in the middle, and each of the at least one pair of drive systems includes a covered cylindrical yoke and a yoke attached in the axial direction of the yoke. A magnetic circuit is constituted by a magnet that is magnetized and provided approximately at the center within the yoke, and a coil attached to the optical system is positioned within the gap between the inner wall of the open end of the yoke and the peripheral wall of one end of the magnet. It is characterized by

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. The magnetic circuit 90 is composed of a cylindrical yoke 91 with a lid, and a cylindrical magnet 92 that is magnetized in the axial direction of the yoke 91 and fixed approximately at the center of the yoke 91. In such a structure, when compared with the structure of the conventional magnetic circuit 9 (shown in the first diagram), the pole piece is omitted and the open end of the yoke 91 does not protrude inward, so the outer diameter and height are reduced and It is possible to reduce the weight. In the magnetic circuit 90, the drive coil 1 attached to the pickup 1 via the holding member 4 is located in the gap between the inner wall of the open end of the yoke 91 and the peripheral wall of one end of the magnet 92.
2 is positioned.

FIG. 4 shows an example of the measured value of the magnetic flux distribution of the magnetic circuit 90. As can be understood from this measured value, the magnetic flux density near the gap is approximately 2000 to 3200 Gauss, which is sufficient for the magnetic circuit. This shows that it can be put to practical use. Therefore, 4
Four drive coils 1 are positioned at the gap of each magnetic circuit in the drive mechanism sections 3a to 3d.
By appropriately combining the drive signals applied to the pickups 2 and 2, the pickup 1 can be vibrated in the focusing direction, the tracking direction, and the tangential direction.

In the above embodiment, a configuration using four drive mechanism sections has been described, but it is sufficient to have at least one pair of drive mechanism sections, and it is of course possible to adapt to a configuration using, 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 outer diameter and height of each magnetic circuit can be reduced and the weight can be reduced, so that the entire device can be made smaller and lighter. Furthermore, since the number of parts can be reduced, costs can be reduced and assembly can be facilitated.

[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. FIG. 4 is a diagram showing the magnetic flux distribution of the magnetic circuit in FIG. 3. Explanation of the symbols of the main parts, 1...Pickup,
3a to 3d...drive mechanism section, 6,91...yoke, 7,92...magnet, 9,90...magnetic circuit, 12...drive coil.

Claims (1)

[Scope of utility model registration request] A driving device for driving an optical system for irradiating a recording surface of a recording medium with spot light, the driving device comprising at least a pair of optical systems that are provided so that the optical system is located in the middle and that drive the optical systems in the same direction. Each of the at least one pair of drive systems includes a cylindrical yoke with a lid, a cylindrical magnet magnetized in the axial direction of the yoke and provided approximately at the center of the yoke, and an opening in the yoke. An optical system driving device comprising: a coil attached to the optical system via a holding member so as to be located in a gap between an inner end wall and a peripheral wall of one end of the magnet.