JPS62239431A - Optical system driving device - Google Patents

Abstract

PURPOSE:To prevent the fall of the optical axis of an optical system by providing a means which holds the optical system and elastic supporting means which pull and support this optical system holding means from both sides facing each other. CONSTITUTION:Pole braces 64a and 64b are stood in both end parts in the direction of an arrow A on a base 62 and have upper parts connected to each other by a plate-shaped elastic body 66. It is preferable that a metallic plate 67a whose both faces damping layers 67b consisting of a rubber or the like are stuck to is used as the plate shaped elastic body 66 with respect to oscillation characteristic. The plate-shaped elastic body 66 is plane in the center part and has equal waveform parts 68a and 68b in both sides, and a circular aperture for securing of an optical path is provided in the center part of the plate-shaped elastic body 66, and the plate-shaped elastic body 66 is pulled slightly. Center parts of pole braces 64a and 64b are connected to each other by a plate shaped elastic body 70, and the plate-shaped elastic body 70 has the same constitution and characteristic as the late-shaped elastic body 66 practically.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical system driving device, and particularly to a device capable of driving an optical system two-dimensionally. Such an optical system drive device is suitably used, for example, to drive an objective lens of an optical head in an optical information recording/reproducing device.

[Conventional technology and its problems]

Conventionally, optical information recording and reproducing devices have been put into practical use, which record information on a recording medium and/or reproduce information recorded on the recording medium while irradiating the surface of the information recording medium with a spot of laser light. has been made into

An example of such a device is an optical disk device. An optical disk, which is a recording medium on which information is reproduced by an optical disk device, has information tracks formed in a helical or concentric shape, each consisting of a row of information focuses each having a width of about 1 to 2 μm and a length of about 1 to 3 μm. When reproducing the information recorded as the information pit string, without rotating the optical disk, a laser beam is irradiated from an optical head in the form of a minute spot onto the information track of the optical disk, and the information pit string is scanned by the beam spot. let When a photodetector detects the reflected light or transmitted light of the light irradiated onto the optical disk surface in this way, the optical properties of the light incident on the photodetector are determined depending on whether or not there is an information bit at the Heemsbot position. changes. In this way, a reproduced signal corresponding to the information pit string can be obtained.

One of the features of optical discs is that they are capable of high-density recording, so the information focus is quite small as mentioned above.
For this reason, in an optical disk device, in order to reproduce accurate information, the light beam spot always accurately follows the information track (tracking) and the light beam spot always accurately focuses on the information track (focusing).
It is necessary. For this reason, optical disk devices generally perform auto-tracking control to correct deviations in the position of the light beam spot caused by eccentricity of the optical disk, and autofocusing control to correct out-of-focus caused by warping of the optical disk.

As a method for realizing such auto-tracking control and auto-focusing control, the objective lens, which is the light beam focusing means of the optical head, is movable in the direction of the optical axis of the lens and in the direction orthogonal thereto using a spring-like structure. A method is generally used in which the objective lens is driven so as to reduce the positional deviation and defocusing of the light beam spot based on detection signals of the positional deviation and defocusing of the light beam spot.

FIG. 9 is a perspective view showing a conventional optical head objective lens drive device having means for such auto-tracking control and auto-focusing control.

In FIG. 9, 2 is a base, and a yoke 6 to which a permanent magnet 4 is attached is fixed on the base. One end of a pair of leaf springs 8a, 8b each located in a vertical plane is fixed to the yoke, and the opposing vertical end surface of a square relay plate 10 is fixed to the other end of the leaf spring. One end of a pair of leaf springs 12a and 12b, each located in a horizontal plane, is fixed to the opposing horizontal end surfaces of the relay plate 100, and an objective lens holder 14 is fixed to the other end of the leaf spring. There is. 16 is an objective lens held by the holder. On the other hand, a yoke 20 to which a permanent magnet 18 is attached is fixed to the base 2.

A coil 22 wound horizontally is attached to the objective lens holder 14 on the side of the permanent magnet 4, and the coil 22 is arranged so as to surround a part of the yoke 6.

A coil 24 wound vertically is attached to the permanent magnet 18 side of the objective lens holder 14.
The coil is arranged to surround a part of the yoke 20.

Note that the base 2 is provided with a through hole 26 below the objective lens 16, thereby ensuring an optical path for the light beam passing through the objective lens 16.

In the objective lens drive device as described above, the relay plate 10
, the plate springs 12a, 12b, the objective lens holder 14, the objective lens 16, and the coils 22.24 can swing in the horizontal direction relative to the yoke 6 via temporary springs 13a, 3b. This realizes horizontal movement of the objective lens 16 (ie, movement for auto-tracking control).

This movement is driven by electromagnetic interaction between the coil 22 and the permanent magnet 4 by passing a current through the coil 22.

Further, the portion consisting of the objective lens holder 14, the objective lens 16, and the coils 22 and 24 is a plate spring 12a.

The objective lens 16 can be oscillated in the vertical direction with respect to the relay plate 10 via the relay plate 12b, thereby realizing vertical movement of the objective lens 16 (that is, movement for autofocusing control). This movement is driven by electromagnetic interaction between the coil 24 and the permanent magnet 18 by passing a current through the coil 24.

However, in the conventional objective lens driving device as described above, since the movable part is supported in two stages by plate springs, the optical axis of the objective lens may be tilted due to twisting of the plate springs. There has been a problem in that resonance occurs with high-frequency drive signals, resulting in unstable operation.

[Background of the invention]

As a solution to the problems of the conventional objective lens drive device as described above, an objective lens drive device as shown in FIG. 10 can be considered.

In FIG. 10, 32 is a base, and permanent magnets 34a, 34b, 34. C.

Support members 36a, 36b, 36c that can support 34d.

36d is fixed, and furthermore, on the base 32 there are supporting members 40a that can support permanent magnets 38a and 38b, respectively.
40b is fixed. Further, on the base 32 are the supporting members 36b and 36c.

A cylindrical support shaft 42 in the above direction is fixed to a portion surrounded by 40a and 40b.

In FIG. 10, 44 is an objective lens holder. A bearing 46 is provided in the center of the holding body, and the cough bearing is rotatably adapted to the support shaft 42. An objective lens 48 is held by the objective lens holder 44, and a weight 50 having approximately the same weight as the objective lens 48 is fixed at a symmetrical position with respect to the objective lens 48 and the bearing 46. There is. The objective lens holder 44 has a substantially cylindrical outer peripheral surface whose axis is in the direction of the bearing 46, that is, in the vertical direction, and a coil 52 wound around the vertical direction is attached to the outer peripheral surface. . Then, the objective lens holder 44
When the bearing 46 and the support shaft 42 are matched, the coil 52 is located between the permanent magnets 34a and 34b and between the permanent magnets 34c and 34d. Further, in this state, coils 54a and 54b are wound horizontally on the outer periphery of the objective lens holder 44 facing the permanent magnets 38a and 38b, respectively.
is attached.

Note that the base 32 is provided with a through hole 56 below the objective lens 48, thereby ensuring an optical path for the light beam passing through the objective lens 48.

In the objective lens drive device as described above, the coil 54
By passing current through a, 54b, permanent magnets 38a, 3
8b, the objective lens holder 44, objective lens 48, weight 50, and coils 52, 54a, 54b
is rotated at an appropriate angle around the shaft 42 via a bearing 46, thereby achieving auto-tracking.

Also, by passing current through the coil 52, the permanent magnet 34
Objective lens holder 44, objective lens 48, and weight 50 due to electromagnetic action between a, 34b and permanent magnets 34C, 34d.
, and coil 52.54a.

54b slides up and down along the support shaft 42 via the bearing 46, thereby performing autofocusing.

According to such an objective lens driving device, the above-mentioned problems of the conventional device as shown in FIG. 9 can be solved.

However, in the objective lens movement device as shown in FIG. often does not completely match the direction of the support shaft 42, and therefore stick-slip is likely to occur between the support shaft 42 and the bearing 46. Therefore, it is necessary to smoothly move the objective lens 48 in the vertical direction. becomes difficult.

Therefore, the present invention solves both the problems of the conventional drive device as shown in FIG. 9 and the problems of the drive device as shown in FIG. It is an object of the present invention to provide an optical system drive device that hardly causes collapse and operates smoothly and favorably.

[Summary of the invention]

According to the present invention, the above object is characterized by comprising an optical system, means for holding the optical system, and elastic support means for tensioning and supporting the optical system holding means from opposite sides. This is achieved by an optical system drive.

〔Example〕

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

FIG. 1 is a plan view showing a first embodiment of the optical system driving device of the present invention, FIG. 2 is a sectional view taken along
The figure and FIG. 4 are a sectional view taken along line I[-III and IV-IV in FIG. 2, respectively, and FIG. 5 is a sectional view taken along line ■-■ in FIG. This embodiment is applied to driving an objective lens of an optical information recording/reproducing device.

In FIGS. 1 to 5, 62 is a base, and on the base there are pillars 64a at both ends in the direction of arrow A (horizontal direction),
64b is erected. The upper parts of these pillars are connected by a plate-like elastic body 66. The plate-shaped elastic body may be made of only a metal plate, but as shown in the enlarged view of FIG. Preferable from the viewpoint of characteristics. The plate-like elastic body 66 has a flat central portion, but has equal corrugated portions 68a and 68b on both sides. Further, a circular opening is provided in the center of the plate-like elastic body 66 to ensure an optical path. The plate-like elastic body 66 is in a slightly tensioned state.

The center portions of the pillars 64a and 64b are connected to a plate-shaped elastic body 7.
Connected by 0. The plate-shaped elastic body 70 has substantially the same configuration and characteristics as the plate-shaped elastic body 66 described above. still,
72a and 72b are the above 68a.

This is a waveform portion similar to 68b.

An objective lens holder 74 is fixedly provided between the central portion of the plate-shaped elastic body 66 and the central portion of the plate-shaped elastic body 70, and the objective lens 76 is held by the holder. The objective lens has an optical axis in the direction of arrow B (vertical direction) orthogonal to the direction of arrow A, so that the light flux passing through the objective lens 76 passes through the central circular aperture of the plate-shaped elastic body 66.70. It has become.

Substantially equivalent coils 78 are wound around the direction of arrow A on two opposing sides of the objective lens holder 74.
a and 78b, and a coil 8 wound around the direction of arrow B is attached to the lower part of the objective lens holder 74.
0 is attached.

As shown in FIG. 3, there is an arrow A in the coil 78a.
A yoke 82a-1 is inserted from one side in the direction, and a yoke 82a-1 is inserted outside the coil 78a to face the yoke.
a-2 is arranged, and a permanent magnet 84a is arranged between the ends of the two yokes. Similarly, inside the coil 78b, the yoke 82b-
1 is inserted, and a coil 7 is inserted so as to face the yoke.
A yoke 82b-2 is arranged outside 8b, and a permanent magnet 84b is arranged between the ends of the two yokes.

As shown in FIG. 1, one set of yokes 82a-1, 82a-2 and permanent magnet 84a is supported by a column 86 provided on the base 62, and the other yoke 82b -1, 82b-2 and the set of permanent magnet 84b are also supported by a support (not shown) similar to the support support 86 described above.

As shown in FIGS. 4 and 5, a yoke 88a-1 is inserted into the coil 80 from below in the direction of arrow B, and a yoke 88a-1 is placed outside the coil 80 to face the yoke.
8a-2 is arranged. As shown in FIG. 5, the lower end of the yoke 88a-1 is fixed to the base 62, and the lower end of the yoke 88a-1 and the yoke 88a-
A permanent magnet 90a is arranged between the lower end of the magnet 2 and the lower end of the magnet 90a. Similarly, within the coil 80 are the yokes 58a-t.
Yoke 8 from below in the direction of arrow B at a position facing
8b-1 is inserted, and a yoke 88b-2 is arranged outside the coil 80 so as to face the yoke. As shown in FIG. 5, a permanent magnet 90b is arranged between the lower end of yoke 88b-1 and the lower end of yoke 88b-2.

As shown in FIGS. 2 and 5, the base 62 is provided with a through hole 92 below the objective lens 76, thereby ensuring an optical path for the light beam passing through the objective lens 76. ing.

In the device of this embodiment as described above, the permanent 611 stone 84
The objective lens holder 74, the objective lens 76, and the coils 78a and 78b are
, 80 moves in the six directions of arrows. That is, when the movable portion receives a force in the six directions of arrows, one of the waveform portions 68a, 72a of the plate-like elastic bodies 66 and 70 is expanded (or contracted) in the direction of arrow A, and at the same time, the other waveform portion 68b is expanded (or contracted) in the direction of arrow A. , 72b are contracted (or expanded) in the direction of arrow A, and the movable portion moves in the direction of arrow A, thereby performing auto-tracking.

In addition, by passing current through the coil 80, the permanent magnet 90
Due to the electromagnetic action between a and 90b, the movable part moves in the direction of arrow B.
move in the direction. That is, when the movable portion receives a force in the direction of arrow B, the waveform portions (
i8a, 68b, 72a.

72b is extended and the movable portion moves in the direction of arrow B, thereby performing autofocusing.

The plate-shaped elastic bodies 66 and 70 have substantially superior characteristics as described above, and furthermore, the above-mentioned coils 78a and 78b.

80 is arranged so that force is applied to the center of gravity of the movable part during auto-tracking movement and auto-focusing movement of the movable part, so the objective lens 76 moves substantially parallel to the optical axis of the objective lens. No collapse occurs.

FIG. 6 is a plan view showing a second embodiment of the optical system driving device of the present invention, and shows the same parts as in FIG. 1 above. Further, FIG. 7 is a cross-sectional view taken along the line ■-■ in FIG. 6. still,
In FIGS. 6 and 7, the same members as in FIGS. 1 to 5 are given the same reference numerals.

In this embodiment, coils 78a, 78b, 80 attached to the objective lens holder 74, a column 86 fixed to the base 62, etc., and a yoke 82a-1.8
2 a-2, 82b-1, 82b-2, 88a-1, 8
8a-2゜88 b-1, 88b-2 and permanent magnet 84
a, 84b.

The only difference from the first embodiment is that the overall arrangement of 90a and 90b is shifted by an angle of exactly 90 degrees.

Therefore, in this embodiment, auto-focusing drive is performed in the same manner as in the first embodiment, but auto-trunking drive is performed by moving the objective lens 7 as shown by the dotted line in FIG.
This is done by moving the movable parts including 6 in the direction of arrow C. That is, during auto-tracking drive, the movable portion receives a force in the direction of arrow C, so that the waveform portions 68a, 68b, 72a,
72b bends and the movable portion moves in the direction of arrow C, thereby performing auto-tracking.

FIG. 8(a) is a partial plan view showing another specific example of the plate-shaped elastic body, and FIG. multiple holes in 9
8 is formed. By configuring the plate-like elastic body in this manner, it is possible to drive with a smaller driving force.

In the above embodiment, the plate-shaped elastic bodies 66 and 70 that can support the objective lens holder 74 are both integrally constructed, but in the present invention, the elastic support means is formed of separate members from both sides of the optical system holding means. It may also be something that supports tension.

Further, in the above embodiment, a plate-like elastic body having a corrugated portion is used as the elastic support means, but in the present invention, the elastic support means may be made of rubber or other appropriate elastic body. good.

Also, in the present invention, the elastic support means may have only one elastic support on each side, or even three or more elastic supports on each side.

Further, although the above embodiment is applied to driving an objective lens of an optical information recording/reproducing apparatus, the present invention can be applied to driving other appropriate optical systems. The optical system to be driven is not limited to a lens or a lens system, but may be a mirror, a prism, or a composite optical system including these.

〔Effect of the invention〕

According to the present invention as described above, since a two-stage temporary spring is not used as a support means, there is almost no occurrence of unnecessary resonance or tilting of the optical axis of the optical system when driving the optical system, and the sliding part Since there are no bumps, the operation is good and smooth.

[Brief explanation of drawings]

Fig. 1 is a plan view of the optical system driving device, Fig. 2 is a cross-sectional view of the optical system drive device, and Figs.
They are a ■-■ cross-sectional view and an IV-IV cross-sectional view in the figure,
FIG. 5 is a sectional view taken along the line V-V in FIG. 4. FIG. 6 is a plan view of the optical system driving device, and FIG. 7 is a sectional view taken along the line 1--2. FIG. 8 (al is a partial plan view of the plate-like elastic body, and FIG. 8(b) is a BB sectional view thereof. FIG. 9 is a perspective view of the optical system drive device. FIG. 10 is an exploded perspective view of the optical system drive device. 62: Base, 64a, 64b: Support column, 66.70: Plate-shaped elastic body, 68a, 68b, 72a, 72b: Waveform portion, 7
4: Objective lens holder, 76: Objective lens, 78a, 7
8b, 80: Coil, 82 a-182a-2, 82b
-1,82b-2,88a-1゜88a-2,88b
-L 88 b-2: Yoke, 84a, 84b, 90
a, 90b: Permanent magnet. Agent Patent Attorney Minoru Yamashita Figure 3 Figure 4 τT Figure 5 Figure 7 Figure 8

Claims (2)

[Claims] (1) An optical system driving device comprising an optical system, means for holding the optical system, and elastic support means for tensioning and supporting the optical system holding means from opposite sides. (2) The optical system driving device according to claim 1, wherein the elastic support means includes a plate-like elastic body having a corrugated portion.