JPH08180440A - Biaxial actuator - Google Patents

Abstract

PURPOSE: To obtain a damping effect enough in the focusing direction without changing the characteristic relative to the tracking direction in a simple constitution by providing damping members to connect elastic supporting members with each other arranged side by side in the focusing direction on both sides of a lens holder. CONSTITUTION: Current based on a focusing servo signal and a tracking servo signal respectively are supplied to a focusing coil 12b and a tracking coil 12c, wound around a coil bobbin 12 of the biaxial actuator 10. Consequently, an objective lens 11c supported by the lens holder 11 is driven in the focusing direction Fcs and in the tracking direction Trk by alternating fields generated from the coils 12b and 12c. The elastic supporting members 13a-13d for supporting the holder 11 are damped in their end part areas 15 respectively. Viscous substance 16 is applied on fixing part areas of the members 13a-13d and is cured. Thus, the members 13a-13d are damped in the end part areas 15 respectively. Moreover, the members 13a-13d are damped in their relative displacement in the focusing direction by the damping members 17 provided in their intermediate parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxial actuator for an optical pickup used for recording / reproducing signals of an information recording medium for CD, MD, etc. and data storage.

[0002]

2. Description of the Related Art Conventionally, an optical pickup is used to reproduce or record an information signal on an information recording medium such as an optical disk, for example, a so-called compact disk (CD) or a magneto-optical disk. This optical pickup includes a semiconductor laser as a light source, an objective lens, an optical system, and a photodetector.

In an optical pickup, a light beam emitted from a semiconductor laser is focused on a recording surface of an optical disc by an objective lens via an optical system. The return light beam from the optical disc is separated from the light beam emitted from the semiconductor laser by the optical system and is guided to the photodetector. The light beam emitted from the semiconductor laser follows the displacement of the optical disc in the direction orthogonal to the surface direction of the optical disc caused by the warp of the optical disc, etc., and is focused on the recording surface of the optical disc. The position of the objective lens in the optical axis direction is adjusted. At the same time, the position in the direction orthogonal to the optical axis of the objective lens is adjusted so that the position of the spot of the light beam emitted from the semiconductor laser on the optical disc follows the eccentricity of the optical disc and the meandering of the track formed on the optical disc. To be done.

The focus position of the light beam emitted from the semiconductor laser and the spot position on the recording surface of the optical disc are adjusted by adjusting the objective lens in the optical axis direction of the objective lens and in the direction orthogonal to the optical axis. It is done by adjusting. An electromagnetically driven actuator is used to adjust the position of the objective lens. This actuator is called an objective lens actuator or a biaxial actuator, and includes a bobbin to which the objective lens is attached, a plurality of elastic supporting members, and a drive unit that generates a driving force.
The bobbin is supported by a plurality of elastic supporting members with respect to the fixed portion such that the position in the optical axis direction of the objective lens, that is, the focus position and the position in the direction orthogonal to the optical axis of the objective lens, that is, the tracking position, are adjustable. ing. An example of this biaxial actuator will be described below with reference to FIG.

Such a biaxial actuator is constructed, for example, as shown in FIG. In FIG.
The biaxial actuator 1 includes a lens holder 2 having an objective lens 2a attached to a tip thereof, and the lens holder 2
To the coil bobbin 3 attached by adhesion or the like
And have.

The lens holder 2 has two ends perpendicular to the fixed portion 4 by two pairs of elastic supporting members 5 having one end on both sides of the lens holder 2 and the other end fixed to the fixed portion 4. Direction, that is, the tracking direction indicated by the reference symbol Trk and the focusing direction indicated by the reference symbol Fcs are movably supported.

Further, the coil bobbin 3 is wound with a focusing coil and a tracking coil (not shown). By energizing the focusing coil and the tracking coil, the magnetic flux generated in each coil interacts with the magnetic flux generated by the yoke 6 integrally attached to the fixed portion 4 and the magnet 7 attached thereto. It has become.

Further, the elastic support member 5 is formed of an elastic body and is fixed between the lens holder 2 and the fixing portion 4 so as to be parallel to each other.

According to the biaxial actuator 1 having the above-described structure, the driving voltage is supplied to each coil from the outside, so that the magnetic flux generated in each coil interacts with the magnetic flux generated by the yoke 6 and the magnet 7. This causes the coil bobbin 3 to move in the tracking direction Trk and the focusing direction Fcs. Thus, the objective lens 2a attached to the lens holder 2 is appropriately moved in the focusing direction and the tracking direction.

[0010]

By the way, in the biaxial actuator 1 having such a structure, the movable part assembly including the lens holder 2 and the coil bobbin 3 is
On both sides thereof, the upper and lower elastic support members 5 support the fixed portion 4 so as to be movable in the biaxial direction, that is, the focusing direction and the tracking direction. The elastic support member 5 is damped in the vicinity of the end on the fixed portion 4 side.

However, according to the above-mentioned damping near the end, damping in focusing control is not sufficient. Therefore, for example, when the biaxial actuator 1 is incorporated in a vehicle-mounted optical disk device or the like, vibration from the outside is prevented. Cannot be completely absorbed. Therefore,
There is a problem that the reproduction of the optical disk cannot be performed reliably.

Therefore, if the damping strength of the elastic support member 5 is increased, the spring constant in the tracking direction also increases, making it difficult to secure the low-frequency gain of the tracking servo and the elastic support. There is a problem that restrictions on processing of the member 5 are increased, and the life of the processing die of the elastic support member 5 is significantly shortened.

In view of the above points, the present invention provides a biaxial actuator having a simple structure and capable of performing sufficient damping in the focusing direction without changing the characteristics in the tracking direction. It is an object.

[0014]

According to the present invention, the above object is to provide a lens holder for supporting an objective lens and both sides of the lens holder for elastically supporting the lens holder with respect to a fixed portion. A plurality of elastic supporting members arranged side by side in the focusing direction, a coil bobbin provided in the lens holder, a focusing coil wound around the coil bobbin, and a tracking wound around the coil bobbin. Coil for use, and a vibration damping member that connects elastic supporting members arranged side by side in the focusing direction to each other on both sides of the lens holder, is achieved by a biaxial actuator.

In the biaxial actuator according to the present invention, preferably, the vibration damping member is applied between two connecting portions and a connecting portion extending from an intermediate portion of each elastic supporting member toward the elastic supporting members facing each other. And a gel material to be formed.

In the biaxial actuator according to the present invention, preferably, the connecting portion is a bent portion integrally formed with each elastic supporting member.

In the biaxial actuator according to the present invention, preferably, the connecting portion is a mold portion in which each elastic supporting member is outsert-molded.

In the biaxial actuator according to the present invention, preferably, the vibration damping member is a mold portion directly fixed to one of the elastic supporting members and fixed to the other via a gel material. .

In the biaxial actuator according to the present invention, preferably, the vibration damping member is a mold portion fixed to both of the elastic supporting members via a gel material.

[0020]

According to the above construction, the lens holder for holding the objective lens is supported by the elastic supporting member.
Therefore, by energizing the focusing coil or the tracking coil, the lens holder is moved in the focusing direction or the tracking direction against the tension of the elastic support member, and the objective lens is focused or tracked.

Here, when the biaxial actuator is moved in the focusing direction, the elastic supporting members arranged in the focusing direction are connected to each other by the damping member, so that the relative displacement in the focusing direction is caused. Damping is performed, and a sufficiently large Q damping in the focusing direction is obtained. Therefore, the vibration in the focusing direction from the outside is reliably absorbed. It should be noted that, when moving in the tracking direction, the two elastic support members connected by the vibration damping member deform in the same direction as each other, so that it is possible to deform in the tracking direction without being affected by the vibration damping member. Become. Therefore, the spring constant in the tracking direction does not increase.

In the case where the vibration damping member is composed of a connecting portion extending from an intermediate portion of each elastic supporting member toward the elastic supporting members facing each other, and a gel material applied between the two connecting portions. With a simple configuration, the two elastic support members are connected by the vibration damping member.

When the connecting portion is a bent portion integrally formed with each elastic supporting member, the connecting portion is formed at the same time when the elastic supporting member is formed, and then bent. By doing so, it is easily configured.

When the connecting portion is a molded portion which is outsert-molded on each elastic supporting member, for example, when the lens holder is outsert-molded on the elastic supporting member, the connecting portion is simultaneously formed. And is easily configured.

When the damping member is a mold portion directly fixed to one of the elastic supporting members and fixed to the other via a gel material, the damping member can be easily formed. Will be done.

When the damping member is a mold part fixed to both of the elastic supporting members via a gel material, the damping member is easily formed and the conventional biaxial actuator is used. It is possible to easily add to the elastic support member.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to FIGS. In addition, since the Examples described below are preferred specific examples of the present invention, various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. The embodiment is not limited to these embodiments unless otherwise stated.

1 to 3 show an embodiment of a biaxial actuator according to the present invention. 1 to 3, the biaxial actuator 10 includes a lens holder 11,
Coil bobbin 12, a plurality of elastic support members 13a, 13
b, 13c, 13d, the fixing portion 14, and the yoke 31 are included.

As shown in FIG. 3, the lens holder 11 is divided into an upper portion 11U and a lower portion 11L by a horizontal dividing line, and they are adhered to each other with an adhesive. Further, the lens holder 11 has a structure shown in FIG.
As shown in, the opening 1 in which the coil bobbin is attached
1a is formed, and a recess 11b to which the objective lens is attached is also formed. A hole through which the light beam emitted from the semiconductor laser or the return light beam from the recording surface of the optical disk passes is formed on the bottom surface of the recess 11b. In the concave portion 11b of the lens holder 11,
The objective lens 11c is attached by adhesion or the like.

Further, the lens holder 11 is supported by elastic supporting members 13a, 13b, 13c, 13d so as to be movable in the focusing direction Fcs and the tracking direction Trk.

The coil bobbin 12 is formed with an opening 12a into which a magnetic circuit composed of a yoke 31 integral with the base and a magnet 32 attached to the inner surface of the inner yoke 31a is inserted, and a focusing coil 12b. And a tracking coil 12c. The focusing coil 12b is wound around the coil bobbin 12 along an axis parallel to the optical axis of the objective lens 11c. In addition, the tracking coil 12
The c is formed by winding a coil in an elliptical shape or a rectangular shape, and is attached to one side surface of the focusing coil 12b. The upper surface of the coil bobbin 12 is covered with the yoke bridge 36. The yoke bridge 36, together with the yoke portion of the magnetic circuit,
It may constitute a closed magnetic circuit. Coil bobbin 1
2 is attached to the opening formed in the lens holder 11 with the focusing coil 12b and the tracking coil 12c attached.

The elastic support members 13a, 13b, 13
It is preferable that c and 13d have conductivity and have spring property, and for example, phosphor bronze, beryllium copper, titanium copper, tin-nickel alloy, stainless steel, or the like is used. Due to these, in the present embodiment, for example, a leaf spring suspension is formed by thin sheet metal, and is fixed between the lens holder 11 and the fixing portion 14 so as to be parallel to each other. As a result, the elastic support members 13a, 13b, 13c, 13d supply the drive current from the external current supply means (not shown) to the focusing coil 12b and the tracking coil 12c wound around the coil bobbin 12. It may be configured as follows.

Further, the elastic support members 13a, 13b, 1
A viscous body 16 acting as a damper is applied to the end regions 15 of 3c and 13d and hardened. The lens holder 11 and the fixing portion 14 are four elastic support members 13
a, 13b, 13c, 13d are connected,
The fixed portion 14 is attached to the adjustment plate 30. The adjusting plate 30 is for adjusting the fixing position of the fixing portion 14 when the biaxial actuator 10 is assembled. The adjusting plate 30 is fixed to the base 31 formed integrally with the yoke by soldering or the like.

The adjustment plate 30 is attached to the base 31 with respect to the rising portions 30a extending upward from both sides near the rear end of the adjustment plate 30 with respect to the rising portions extending upward from both sides of the rear end of the base 31. It is done by soldering. Here, the base 31 is provided with a pair of yokes 31a and 31b forming the magnetic circuit by bending the ends of the base 31 on the objective lens side upward, respectively, and the opposing yoke 31b of the inner yoke 31a. Permanent magnet 3 mounted on the inner surface facing the
2 is provided. Thereby, the pair of yokes 31
A magnetic circuit is configured by a and 31b and the permanent magnet 32.

Then, as described above, when the fixing portion 14 is attached to the base 31, the focusing coil 12b and the tracking coil attached to the coil bobbin 12 are provided in the gap between the opposing yoke 31b and the permanent magnet 32. 12c is inserted. At the same time, the inner yoke 3
1a and the permanent magnet 32 are the openings 1 of the coil bobbin 12.
It will be inserted in 2a. The elastic support member 13
Among a, 13b, 13c and 13d, elastic support members 13a and 13b, 13c and 13 arranged in the focusing direction.
A vibration damping member 17 that connects d to each other is provided.

The damping member 17 is formed, for example, as shown in FIG. That is, in FIG. 4, the damping member 1
Reference numeral 7 denotes a connecting portion 18 that projects outward from an intermediate portion of the elastic supporting member 13a or 13c located above in the focusing direction and extends downward, and an elastic supporting member 13b or 13 located below in the focusing direction.
It is composed of a connecting portion 19 protruding outward from the intermediate portion of d and extending upward, and a gel material 20 applied between the tip portions of the connecting portions 18 and 19 facing each other.

In the illustrated case, the connecting portions 18 and 19 are
The elastic support member 13 is formed by, for example, press molding.
It is formed integrally with a, 13c or 13b, 13d and by bending. And the connecting portion 18
Is located outside the connecting portion 19 and the connecting portion 18
And 19 so that there is a slight gap between them. Then, the gel material 20 applied in this gap
By being filled with
They are connected to each other via a gel material 20. here,
The gel material 20 is, for example, a silicone-based gel material such as “31X-014-4” of ThreeBond Co., Ltd.,
An acrylic gel material such as "PDM-2" from Kyoritsu Chemical Industry Co., Ltd. is used.

Biaxial actuator 10 according to this embodiment
Is configured as described above, and currents based on the focus servo signal and the tracking servo signal are supplied to the focusing coil 12b and the tracking coil 12c wound around the coil bobbin 12, respectively. Thereby, the DC magnetic field of the magnetic circuit, the focusing coil 12b, and the tracking coil 12c.
The lens holder 11, that is, the objective lens 11c is driven in the focus direction Fcs and the tracking direction Trk by the alternating magnetic field generated by

Further, as a damper, the elastic support member 13 is used.
The viscous body 16 is applied to the end regions 15 of the a, 13b, 13c, and 13d on the side of the fixed portion 14 and hardened. Thereby, the elastic support members 13a, 13b, 13c, 13d
Will be respectively damped in the end regions 15.

Further, the elastic support members 13a, 13b, 1
With respect to 3c and 13d, the relative displacement in the focusing direction is damped by the vibration damping member 17 provided in the intermediate portion. When the lens holder 11 is moved in the focusing direction as shown in FIG. 5, the elastic support members 13a, 13b or 13c, 13d arranged in the focusing direction are deformed to have the same S-shape. As a result, the connecting portions 18 and 19 facing each other are provided.
Will be relatively displaced as shown, but this displacement will be damped by the gel material 20. Therefore, the elastic support members 13a, 13b or 13
The relative displacement between c and 13d is damped by the vibration damping member 17. As a result, the lens holder 11 can obtain a desired damping characteristic in the focusing direction.

Further, as shown in FIG. 6, when the lens holder 11 moves in the tracking direction, the elastic supporting members 13a, 13b or 1 arranged in the focusing direction are arranged.
3c and 13d are deformed to have the same S-shape. In this case, the connecting portions 18 and 19 facing each other do not shift relative to each other. Therefore, since the gel material 20 of the vibration damping member 17 is not deformed, the elastic support members 13a, 13b or 13c, 13d are not affected by the damping by the vibration damping member 17 when moving in the tracking direction. As a result, in the lens holder 11, only the damping by the viscous body 16 in the end region 15 acts in the tracking direction, so that a desired damping characteristic is obtained. Thus, desired damping characteristics can be obtained in the focusing direction and the tracking direction. As a result, the elastic support members 13a, 13a are
The vibrations of b, 13c and 13d are reliably damped.

7 and 8 show a first modification of the vibration damping member. The vibration damping member 21 is entirely formed of a molding resin into a substantially block shape. further,
The vibration damping member 21 includes one elastic support member, in the illustrated case, a first engagement groove 21a with which the elastic support member 13a or 13c located above in the focusing direction is engaged.
The second engaging groove 21b is provided in which the elastic supporting member 13b or 13d located below in the focusing direction is engaged. The first engagement groove 21a is provided in the elastic support member 13
The dimensions are selected so that the elastic support member 13a or 13c is sandwiched and fixedly held by the engagement of the intermediate portion of a or 13c.

Further, as shown in FIG. 8, the second engaging groove 2
1b is such that the middle portion of the elastic support member 13b or 13d is loosely fitted, and the upper wall surface of the engaging groove 21b is between the upper surface of the middle portion of the elastic support member 13b or 13d.
The lower wall surface of the engaging groove 21b and the elastic support member 13b
Alternatively, the gel material 22 is filled in the gap between the lower surface of the intermediate portion of 13d and the lower surface. Thereby, the second engagement groove 21
The dimension of b is selected so as to hold this elastic support member 13a or 13c through the gel material 22 in the focusing direction.

According to the vibration damping member 21 having such a structure,
The upper elastic support members 13a and 13c are connected to the lower elastic support members 13b and 13b via the damping member 21 and the gel material 22.
It will be connected to 13d. Therefore, similarly to the vibration damping member 17 described above, the upper elastic support member 13
The relative displacement between a, 13c and the lower elastic support members 13b, 13d will be damped by the gel material 22. Like the second engaging groove 21b, the first engaging groove 21a is also formed to be large in the focusing direction and filled with the gel material 22 so that the elastic supporting members 13a and 13c are damped. It may be configured to. In this case, the elastic support members 13a, 13
Since any size of b, 13c, and 13d can be dealt with, it is easy to add to the conventional biaxial actuator.

9 and 10 show a second modification of the vibration damping member. That is, the vibration damping member 23 includes a connecting portion 24 extending downward from a convex portion protruding outward from an intermediate portion of the elastic supporting member 13a or 13c located above in the focusing direction, and an elastic supporting member located below in the focusing direction. A connecting portion 25 extending upward from a protrusion protruding outward from an intermediate portion of 13b or 13d.
And a gel material 26 applied between the ends of the connecting portions 24 and 25 facing each other. In the illustrated case, the connecting portions 24 and 25 are made of synthetic resin or the like integrally with the elastic supporting members 13a, 13c or 13b, 13d by outsert molding. The connecting portion 24 is located outside the connecting portion 25, and is formed so as to have a slight gap between the connecting portions 24 and 25. And in this gap,
By filling the applied gel material 26, the connecting portions 24 and 25 are connected to each other via the gel material 26.

According to the damping member 23 having such a structure,
The upper elastic supporting members 13a and 13c are connected to the lower elastic supporting members 13b and 13d via the connecting portion 24, the gel material 26 and the connecting portion 25. Therefore, similarly to the vibration damping member 17 described above, the upper elastic support members 13a and 13c and the lower elastic support members 13b and 1c.
The relative displacement between 3d will be damped by the gel material 26. In this case, the connecting portions 24, 2
5 is molded simultaneously with the elastic support members 13a, 13b, 13c, 13d when the lens holder 11 is outsert molded. Thereby, the connecting portions 24, 25
Will be formed at low cost without adding new steps.

As described above, in the above-described embodiment, the elastic supporting members arranged in the focusing direction of the biaxial actuator are connected to each other by the damping member during the movement in the focusing direction. Since a large Q-dump in the focusing direction is obtained, vibrations in the focusing direction from the outside are reliably absorbed. Thus, even in a vehicle-mounted optical disk device or the like, the vibration characteristics in the focusing direction are improved, so that the optical disk can be reliably reproduced.

When moving in the tracking direction,
Since it is deformed in the tracking direction without being affected by the vibration damping member, the spring constant in the tracking direction does not increase. Therefore,
The low-frequency gain of the tracking servo can be easily ensured, and the elastic support member can be easily processed as in the conventional case.

Although the elastic supporting members 13a, 13b, 13c and 13d are simply fixed to the lens holder 11 and the fixing portion 14 in the above-mentioned embodiment, the lens holder 11 and Fixed part 1
It is obvious that the 4 may be integrally formed by insert formation or the like. Also, the lens holder 11
Is divided into an upper portion 11U and a lower portion 11L, but it is obvious that they may be integrally formed.

[0050]

As described above, according to the present invention, it is possible to provide a biaxial actuator in which a sufficient damping effect in the focusing direction can be obtained without changing the characteristics in the tracking direction. it can.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing the overall configuration of an embodiment of a biaxial actuator for an optical pickup according to the present invention as seen from the front.

FIG. 2 is a schematic perspective view showing the biaxial actuator of FIG. 1 as viewed from the rear.

FIG. 3 is an exploded perspective view of the biaxial actuator of FIG.

FIG. 4 is an enlarged perspective view around a vibration damping member of the biaxial actuator of FIG.

5 is a schematic side view showing a moving state in the focusing direction in the biaxial actuator of FIG.

6 is a schematic plan view showing a movement state in a tracking direction in the biaxial actuator of FIG.

FIG. 7 is an exploded perspective view showing a modified example of the vibration damping member in the biaxial actuator in FIG.

8 is a sectional view of the vibration damping member of FIG.

FIG. 9 is an exploded perspective view showing another modification of the vibration damping member in the biaxial actuator in FIG.

10 is a cross-sectional view of the vibration damping member of FIG.

FIG. 11 is a schematic perspective view showing an entire configuration of an example of a conventional biaxial actuator for an optical pickup.

[Explanation of symbols]

 10 Biaxial Actuator 11 Lens Holder 11a Opening 11b Recess 11c Objective Lens 12 Coil Bobbin 12a Opening 12b Focusing Coil 12c Tracking Coil 13a, 13b, 13c, 13d Elastic Supporting Member 14 Fixing Part 15 End Region 16 Viscous Body 17, 21,23 Damping member 18,19,24,25 Connection part 20,22,26 Gel material

Claims (6)

[Claims] 1. A lens holder for supporting an objective lens, and a plurality of elastic support members provided side by side in the focusing direction on both sides of the lens holder for elastically supporting the lens holder with respect to a fixed portion. A coil bobbin provided on the lens holder, a focusing coil wound on the coil bobbin, and a tracking coil wound on the coil bobbin. A biaxial actuator, comprising: a vibration damping member that connects elastic supporting members arranged side by side in the focusing direction to each other. 2. The vibration damping member comprises a connecting portion extending from an intermediate portion of each elastic supporting member toward the elastic supporting members facing each other, and a gel material applied between the two connecting portions. The biaxial actuator according to claim 1, wherein 3. The biaxial actuator according to claim 2, wherein the connecting portion is a bent portion integrally formed with each elastic support member. 4. The biaxial actuator according to claim 2, wherein the connecting portion is a mold portion formed by outsert molding on each elastic supporting member. 5. The vibration damping member is a mold portion directly fixed to one of the elastic supporting members and fixed to the other via a gel material. The described biaxial actuator. 6. The biaxial actuator according to claim 1, wherein the vibration damping member is a mold portion fixed to both of the elastic supporting members via a gel material.