JP2000132852A - Optical head actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an elastic supporting member in which extending and contracting vibration along the axial line direction (an approximately X axis direction) of the member in an optical head actuator is reduced and the constitution is provided to reduce the deformation by a bending moment M during the movement in focusing and tracking directions of a lens holder. SOLUTION: Two pairs of elastic supporting members 31 are provided to hang and hold a lens holder 4, that holds an objective lens 5, against a supporting body 1A. The members 31 are practically extended from the body 1A in the direction that is orthogonal to both tracking and focusing directions. Bended sections are provided at approximate center sections between the body 1A and the holder 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a compact disc (CD), a digital versatile disc (DV)
The present invention relates to an optical head actuator for recording and reproducing information on and from a recording medium such as an optical disk such as D) or a magneto-optical disk such as a mini disk (MD).

[0002]

2. Description of the Related Art As shown in FIG. 7, a conventional optical head actuator has a lens holder 4 for holding an objective lens 5 and a support 1A having the lens holder 4 disposed on a base member 1B. Electromagnetic drive means comprising an elastic support member 3 such as two pairs of wires for suspension support, a drive permanent magnet 2 fixed to the base member 1B side, a tracking coil 6 and a focusing coil 7 fixed to the lens holder side. The general configuration is composed of

In the optical head actuator having such a configuration, the elastic support member 3 is formed, for example, by C
The lens holder 4 is made of a material such as a u-Be alloy or a Cu-P alloy, and is protruded from a position corresponding to, for example, each corner of a rectangle set at a predetermined interval on the support 1A. The lens holder 4 is extended substantially in the X-axis direction so as to suspend and support the lens holder 4 at its free end. And the lens holder 4
Generally, it is elastically supported by two pairs of elastic support members 3, and the focusing direction (Z
) And in the tracking (Y-axis) direction. As shown in FIG. 8, the electromagnetic driving means supports the two permanent magnets 2 for driving arranged facing each other with a gap therebetween by means of a soft magnetic yoke 8 having a substantially U-shape, and is wound around a bobbin 11 made of resin or the like. The turned tracking coil 6 and focusing coil 7 are combined so as to be located between the opposing magnetic poles of the driving permanent magnet 2, and are fitted and fixed to the lens holder 4.

Incidentally, the tracking coil 6
Drives the lens holder 4 and thus the objective lens 5 in the track width direction (Y-axis direction) of the disc (not shown), while the focusing coil 7 moves the lens holder 4 and thus the objective lens 5 in the focusing direction (Z direction). (In the axial direction).

That is, when the tracking coil 6 is energized, a force acting in the Y-axis direction is generated in the tracking coil 6 due to the interaction between the current flowing in the Z-axis direction and the magnetic field in the X-axis direction by the driving permanent magnet 2. I do. as a result,
The force acting in the Y-axis direction displaces the lens holder 4 and thus the objective lens 5 in the Y-axis direction, that is, in the direction parallel to the track width of the disk.

Similarly, when the focusing coil 7 is energized, the Z-axis force acts on the focusing coil 7 due to the interaction between the current flowing in the Y-axis direction and the magnetic field in the X-axis direction by the driving permanent magnet 2. I will be. As a result, this force is applied to the lens holder 4 and thus the objective lens 5
Is displaced parallel to the focusing direction, that is, the optical axis direction perpendicular to the recording surface of the disk.

As described above, the lens holder 4 suspended and supported by the two pairs of elastic support members 3 is moved in the tracking direction and the focusing direction by applying an electric current to the tracking coil 6 and the focusing coil 7. Linear vibration in the focusing direction or tracking direction corresponding to the bending vibration of the support member 3, around the Y axis or Z corresponding to the expansion / contraction vibration in the axial direction of the elastic support member 3.
There is a tendency that rotational vibration around the axis, that is, rotational vibration of pitching or yawing is easily generated.

Conventionally, as shown in FIG. 9, a damping member 9 made of a viscoelastic material is provided near the support end of the elastic support member 3 in order to reduce such linear vibration and rotational vibration of the lens holder 4. A structure in which a branch portion 3k is provided at the position of the damping member 9 is adopted in order to mount and reduce expansion and contraction vibration in the axial direction. In such a structure, in particular, the damping member 9 can reduce the bending vibration of the elastic support member 3 in the focusing direction and the tracking direction to some extent, and also has a branch caused by the rotational vibration of the lens holder 4 around the Y axis and the Z axis. It functions to reduce the vibration of the portion 3k.

[0009]

However, the conventional optical head actuator in which the damping member 9 and the branch portion 3k are formed on the elastic support member 3 to reduce the linear vibration and the rotational vibration of the lens holder 4 is as follows. When the lens holder 4 is moved in the focusing direction or in the tracking direction, as shown in FIG. 11, at the fixed end of the elastic support member 3 with the support 1A or the end at which the elastic support member 3 is attached to the lens holder 4. , And receives a large bending moment M in the opposite direction, and is easily deformed. In particular, the branch portion k adjacent to the damping member 9 provided at the fixed end of the elastic support member 3 is subjected to complicated and large deformation because both the bending and the distortion are mixed. Moreover, since the shape of the branch portion 3k is complicated, it is difficult to form each of the branch portions 3k of the two pairs of elastic support members 3 in the same shape and at the same position with high accuracy. Therefore, 2
It is difficult to uniformly deform each of the pair of elastic support members 3. For example, as shown in FIG. 11, a difference in deformation occurs between the portions 3U and 3D of the elastic support member 3 near the support 1A. Will be. That is, the lens holder 4
Tilts around the Y axis to generate a tangential tilt θ, or generates a radial tilt φ as shown in FIG.

An object of the present invention is to provide an optical head actuator which can solve the above-mentioned problems of the prior art, and in particular, expands and contracts the elastic support member in the axial direction (almost the X-axis direction). An object of the present invention is to provide an elastic support member having a structure that is less likely to be deformed by the bending moment M when the lens holder 4 moves in the focusing direction or the tracking direction while reducing vibration.

[0011]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned objects, the inventors have developed the present invention having the following gist configuration. That is, the optical head actuator of the present invention drives two pairs of elastic support members for suspending and supporting the lens holder holding the objective lens with respect to the support, and drives the lens holder in each of the tracking direction and the focusing direction. The elastic support member extends from the support in a direction substantially perpendicular to both the tracking direction and the focusing direction, and a support end of the support is provided. A bent portion is provided substantially at the center between the lens holder and the supporting end of the lens holder.

In the present invention, it is a preferred embodiment that a damping member is attached to a bent portion of the elastic support member.

Further, in the present invention, the elastic support member is provided with a branch extending from the bent portion toward the support end, and the distal end of the branch is attached to the support via a damping member. Is a preferred embodiment.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a plan view showing a first embodiment of the present invention, and FIG. 2 is a side view of the same. In this embodiment, FIGS.
Are the same or similar to those of the conventional optical head actuator shown in FIG.

The optical head actuator according to the present invention is, for example, a pair of four elastic supports made of a linear spring material such as a metal such as a Cu-Be alloy or a Cu-P alloy or a plastic. The member 31 is protruded from a position corresponding to, for example, each corner of a rectangle set at a predetermined interval on the support 1A, and extends toward the lens holder 4 in the axial direction (almost the X-axis direction). The lens holder 4 is suspended and supported at its free end, and electromagnetic drive means for driving the lens holder 4 in the tracking direction (Y-axis) and the focusing direction (Z-axis) are provided.

The electromagnetic driving means comprises two permanent magnets 2 for driving, two coils 6, 7 and a bobbin 11 for holding these coils. The drive permanent magnets 2 are opposed to each other via a gap by a substantially U-shaped soft magnetic pole yoke 8 fixed to the base member 1B, and the respective magnetic poles on the back side are fixed to the soft magnetic yoke 8. . The tracking coil 6 and the focusing coil 7 are wound and held on a bobbin 11 made of resin or the like, and the bobbin is positioned so that the respective coils 6 and 7 are located between opposed magnetic poles of the two driving permanent magnets 2. 11 is fitted and fixed to the lens holder 4.
As another embodiment of the optical head actuator of the present invention, unlike the structure described above, as shown in FIG. 3, a tracking coil 6 and a focusing coil 7 are provided on the base member 1B side, and the driving coil is driven on the lens holder 4 side. It is also possible to provide a moving magnet type optical head actuator provided with the permanent magnet 2 for use in the present invention.

In the present invention, the elastic support member 31 having the most characteristic structure has a substantially central portion in the axial direction, for example, as shown in FIG. Bending part 31k with a crank shape
Is formed. Such an elastic support member 31 is formed directly by means of etching, injection molding, or the like, or is formed by bending a wire, but the crank-shaped bent portion 31k is limited to the two-reciprocating shape described above. Instead, the shape may be a one-way shape or another reciprocating shape, or may be formed by bending on another XZ or YZ plane. In addition, each elastic support member 31 does not necessarily need to be formed parallel to the X axis, and may be formed so as to protrude and extend substantially in the X axis direction.

When the thus structured optical head actuator is driven to move the lens holder 4 in the focusing direction as shown in FIG. 2, for example, a bending moment M is applied to the elastic support member 31. The bending moment M at the mounting end to the support 1A and the holding end with the lens holder 4 is opposite in direction and has the largest magnitude, as described in the conventional example. However, with respect to the elastic support member 31 according to the present invention, the position where the bending moment M is substantially zero is obtained by bending the crank-shaped bent portion 31k.
That is, since the elastic support member 31 is formed substantially at the center in the axial direction, there is a feature that deformation due to the bending moment M hardly occurs.

As described above, since the crank-shaped bent portions 31k are formed substantially at the centers of the respective elastic support members 31 in the axial direction, the difference in deformation due to the bending moment M can be obtained without having the exact same shape and the same position. Can be sufficiently suppressed, so that there is almost no difference in the bending deformation of the elastic support member 31, and therefore, the tangential tilt θ and the radial tilt φ in the lens holder 4 can be effectively suppressed.

FIG. 4 shows a modification of the elastic support member according to another embodiment of the present invention. In this case as well,
Although the crank-shaped bent portion 31k has a shape that is branched into a spinning wheel shape at a substantially central portion in the axial direction of the elastic support member 31, they are common in that both are bent in a crank shape. However, in this modified example,
Since the difference in deformation due to the bending moment M can be sufficiently suppressed, there is almost no difference in the bending deformation of the elastic support member 31, and the occurrence of tangential tilt θ and radial tilt φ in the lens holder 4 can be effectively suppressed. .

FIG. 5 shows still another modification of the present invention.
Also in this case, similarly, the crank-shaped bent portion 31k
Is formed at a substantially central portion of the elastic support member 31 in the axial direction. From this central portion, C is formed in one direction orthogonal to the axial direction.
It differs from the first embodiment in that it swells in a letter shape. Also in this modification, the difference in the deformation due to the bending moment M can be sufficiently suppressed, so that there is almost no difference in the bending deformation of the elastic support member 31, and the generation of the tangential tilt θ and the radial tilt φ in the lens holder 4 is effective. Can be suppressed.

FIG. 6 shows a second embodiment of the optical head actuator according to the present invention. The elastic support member 31 in this embodiment has a substantially central portion in the axial direction,
A crank-shaped bent portion 3 having substantially the same shape as the bent portion shown in FIG.
1k, and a damping member 91 made of a viscoelastic material or the like is attached to the bent portion 31k. By attaching the damping member 91 having the vibration damping function to the bent portion 31k as described above, in addition to more effectively suppressing the occurrence of the tangential tilt θ and the radial tilt φ of the lens holder 4, the crank-shaped bent portion 31k Can be efficiently absorbed, so that the rotational vibration of the lens holder 4 around the Y-axis or the Z-axis caused by the bending vibration can be effectively suppressed.

FIG. 7 shows a third embodiment of the optical head actuator of the present invention. The elastic support member 31 in this embodiment has a crank-shaped bent portion 31k having substantially the same form as the bent portion in the first embodiment shown in FIG. , And the distal end of the branched portion 31B is fixed to the support 1A via a damping member 91 made of, for example, a viscoelastic material. In this example, the distal end portion of the branch portion 31B is formed to be bent in an anchor shape as shown in the figure, and this portion is buried in the damping member 91 so as to increase the contact area between them. It was done.
However, the present invention should not be limited to such a shape, and may be, for example, simply a linear shape. In any case, by adopting such a configuration, in addition to the effect of suppressing the occurrence of tangential tilt θ and radial tilt φ of the lens holder 4, it is possible to effectively absorb the bending vibration of the crank-shaped bent portion 31k. Therefore, the rotational vibration of the lens holder 4 around the Y axis or the Z axis due to this can be suppressed efficiently. Further, since bending vibration of the elastic support member 31 can be suppressed, linear vibration of the lens holder 4 in the focusing direction and the radial direction can also be suppressed.

[0024]

As described above, according to the optical head actuator of the present invention, since the bending portion is formed near the center of the elastic support member in the axial direction, the bending moment M when the actuator is driven is obtained. Can be made almost zero. Therefore, there is almost no difference between the bending deformations of the respective elastic support members, and the tangential tilt θ of the lens holder 4 is reduced.
And radial tilt φ can be effectively suppressed. Further, when a damping member is provided in addition to the crank-shaped bent portion formed on each elastic support member, the occurrence of tangential tilt θ and radial tilt φ of the lens holder can be more effectively suppressed, and the rotation around the Y axis and The effect of suppressing rotational vibration around the Z axis also increases. Furthermore, when each elastic support member is provided with a branch portion from the bent portion toward the support end with the support, and when a damping member is attached to the tip of the branch portion,
In addition to the effects described above, there is also an effect that linear vibration of the lens holder in the focusing direction and the radial direction can be suppressed.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of the present invention.

FIG. 2 is a side view for explaining the operation of the present invention.

FIG. 3 is a plan view showing an example in which the optical head actuator according to the first embodiment of the present invention is applied to a moving magnet type optical head actuator.

FIG. 4 is a plan view showing a modification of the first embodiment of the present invention.

FIG. 5 is a plan view showing another modification of the first embodiment of the present invention.

FIG. 6 is a plan view showing a second embodiment of the present invention.

FIG. 7 is a plan view showing a third embodiment of the present invention.

FIG. 8 is a perspective view for explaining a conventional example.

FIG. 9 is a perspective view of an essential part for explaining a conventional example.

FIG. 10 is an enlarged view showing a conventional elastic support member.

FIG. 11 is a diagram for explaining the operation of the conventional example.

FIG. 12 is a diagram for explaining the operation of the conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1A support 1B base member 2 driving permanent magnet 31 elastic support member 31B branch portion 31k crank-shaped bent portion 4 lens holder 5 objective lens 6 tracking coil 7 focusing coil 8 soft magnetic yoke 91 damping member

Claims (3)

[Claims] 1. A pair of elastic support members for suspending and supporting a lens holder holding an objective lens with respect to a support, and electromagnetic driving means for driving the lens holder in a tracking direction and a focusing direction. Wherein the elastic support member extends from the support substantially in a direction orthogonal to both the tracking direction and the focusing direction, and the support end of the support and the support end An optical head actuator, wherein a bent portion is provided at a substantially central portion between the lens holder and a supporting end. 2. The optical head actuator according to claim 1, wherein a damping member is attached to a bent portion of the elastic support member. 3. The elastic support member according to claim 1, wherein a branch portion extending from the bent portion toward the support end is provided, and a distal end of the branch portion is attached to the support via a damping member. The optical head actuator according to claim 1.