JPS60173727A - Optical scanner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an optical system scanning device used in an optical disk device such as a video disk or a PCM audio disk playback device.

[Background of the invention]

In this type of playback device, focusing (in the optical axis direction) is performed to properly focus the light beam on the disk information plane.
In addition to this operation, it is also necessary to perform a tracking operation (in a direction perpendicular to the optical axis) that causes the focused light spot to accurately follow the information track on the disk. Various optical scanning methods have been proposed to perform the above operations. One type of such technology is known to drive a diaphragm lens in two directions to focus a light spot on a disk (for example, in Japanese Patent Laid-Open No. 55
(Refer to Publication No.-93544). However, this drive device
Small-sized discs such as CM audio discs have a disadvantage in that the inner circumference cannot be reproduced due to their large size.

PCM audio discs must be played up to an inner radius of 25 mm.

The outer diameter of a rotary motor for controlling the rotation of this type of disk correctly and evenly is approximately 30㎜. Therefore, the dimensional restriction of the actuator is that the width of the actuator is 20 an or less.

[Purpose of the invention]

In order to eliminate the above-mentioned drawbacks, the present invention has been miniaturized by arranging a focusing drive coil and a tracking coil in one magnetic gap, and the conventional focusing and tracking drives are separate, which is complicated and requires a large number of parts. It is an object of the present invention to provide a scanning device in which many of the factors that have caused deterioration of characteristics are simplified.

[Summary of the invention]

In the present invention, the conventional magnetic circuit, which has a donut shape symmetrical to the optical axis, is configured only in the direction perpendicular to the direction in which the tracking operation is performed, and both the focusing coil and the tracking coil are placed in the gap of this magnetic circuit. It is characterized by what it did. For this reason, the dimensions of the rotary motor side are made smaller,
The same performance could be achieved with the conventional 172. Furthermore, in the past, processing of the lead wires of the drive coils was a problem. As the coil part moves, the lead wire also moves with it, which has the disadvantage of causing the lead wire to break due to fatigue. In order to eliminate such drawbacks, the present invention provides a coil.

By constructing the suspension tube that supports the optical system with a conductive material, the suspension can also serve as a lead wire, making it possible to have a long life.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows an exploded perspective view of an embodiment of the present invention. FIG. 2 is a plan sectional view thereof. The diaphragm optical system 1 has a support 2.
It is fixed to the upper part of the coil groups 7, 8a to 8d. The coil group includes two permanent magnets 4a, 4b and magnetic members 3a, 3b.
, 5. A 66 is provided at the center of the magnetic member 5 so that the light beam passes through it. Further, the magnetic gap 17 is parallel to the tracking operation direction. Therefore, the circuit disk motor will be in the direction shown by the arrow in the figure. Next, the focusing operation will be explained. The drive coil 7 has a cylindrical shape. As can be seen from FIG. 2, the gap between the coil 7 and the magnetic member 5 has a wide tracking operation stroke so that the coil 7 can move in the tracking direction. Four focus plate springs 9a, 10a are fixed to the focus spring support member 14 by passing current through the coil 7.

11a and 12a are deformed, and the intermediate movable member 13. Tracking leaf springs 9b, 10b, llb, 12b and members 16a, 16b for fixing them to coils etc. are displaced in the focus direction. During this focusing operation, the intermediate movable member 13 and the coil group operate simultaneously while the tracking leaf springs 9b to 12b remain undeformed because they have high rigidity in the focusing direction.

Next, the tracking operation will be explained using FIGS. 3(a) to 3(b). Tracking is driven by four tracking drive coils 88 to 8d (shown as L in FIG. 3(a)) fixed outside the focus drive coil. The tracking drive coils 8a to 8d are shown in FIG. 3(a).
As shown in FIG. 2, only a portion of the magnetic head is fixed within the magnetic gap 17. Therefore, if Fig. 3(b)
As shown in the figure, when currents are applied to 8a, 8c, 8b, and 8d in the direction of the arrows α and β, the coil group operates in the direction of the arrow γ.

Similarly, as shown in FIG. 3(C), when current is passed in the directions of arrows X and Y, the device operates in the direction of arrow Z. During this tracking operation, the focus plate spring has a large rigidity Vl in the tracking operation direction, so the intermediate movable member 13 does not operate, and the tracking plate springs 9b, 10b, llb,
12b is deformed and only the coil group moves in the tracking direction.

Although the operations have been described above, the present invention is characterized in that focusing and tracking operations are possible using only a magnetic gap parallel to the tracking direction.

Therefore, the number of parts that form the static magnetic field can be reduced and the size can be reduced. Furthermore, in this embodiment, conductive metal is used for the leaf springs, 9a and 9b, and 10a and 10b.

11a and llb, 12a and 12b are each consecutive 1
The intermediate movable member is insulated and electrically independent. For this reason, these leaf springs also serve as lead wires for conducting focusing and tracking currents. Conventionally, in the case of a moving coil, there have been serious disadvantages in that the lead wire deforms as the movable part moves, resulting in wire breakage due to fatigue, and the disadvantage that the lead wire moves and causes adverse effects. As shown in the present invention, by eliminating lead wires, it is possible to extend the life of the device. In addition, 15a~
15d is a wire for sustaining the driving circuit and the present scanning device.

〔Effect of the invention〕

By implementing the present invention, the width in the tracking operation direction can be reduced to 1/2 or less compared to a conventional optical scanning device that operates in two directions.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of one embodiment of the present invention, and FIG. 2 is an exploded perspective view of an embodiment of the present invention.
Its plan sectional view, FIG. 3, is an explanatory diagram of its operation. Figure 1 Figure 4 Figure 2 Figure 3

Claims (1)

[Claims] 1. An optical system that focuses a light beam on a predetermined recording medium;
support means for operatively supporting the optical system in the direction of its optical axis and in a first direction perpendicular to the optical axis; and at least one magnetic gap extending in the first direction; a magnetic circuit that forms a magnetic flux substantially orthogonal to both the optical axis and the first in the gap, and are driven independently of each other, first coil means for providing a focusing operation and second coil means for providing a tracking operation. An optical scanning device characterized in that both the coil means are supported together with the optical system by the support means so that a part of the coil means interlinks with the magnetic flux within the magnetic gap. 2. The optical scanning device according to item 1, wherein the support means is made of a conductive member and is used as a conductor for passing current through the first and second coil means. 3. The magnetic circuit has two magnetic gaps parallel to each other, and has an aperture between the two magnetic gaps for the light beam to pass through. optical scanning device. 4. The optical scanning device according to any one of items 1 to 3, wherein the first coil means comprises a rectangular cylindrical coil. 5. Item 1, wherein the second coil means comprises at least a pair of coils that are fixedly installed on the first coil means at least within the magnetic gap and are supplied with currents in opposite directions. The optical scanning device according to any one of Items 4 to 4. 6. Items 1 to 5, wherein the support means is comprised of a plurality of second support members that support the movable member so that the movable member can be moved substantially in parallel in the direction of the optical axis. The optical scanning device according to any one of Items 1 to 9. 7. The optical scanning device according to item 6, wherein the first and second support members are integrally formed.