JPH08147734A - Biaxial actuator - Google Patents

Abstract

PURPOSE: To provide a biaxial actuator in which flowing out of the unhardened portion of a damper provided in an elastic supporting member on the surface of the adhesion part of a fixing part is prevented. CONSTITUTION: A lens holder 11 for supporting an objective lens is supported on a fixing part 14 via elastic supporting members 13a, 13b, 13c and 13d. An adhesive body 16 is applied on adhesive receiving parts 15b and 15e provided in the end area of the fixing parts of these elastic supporting members and hardened as a damper and in adjacent to the adhesive receiving parts 15b and 15e of the elastic supporting members, a adhesive flow preventive wall 14b formed in the fixing part 14 is provided.

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 disc, for example, a so-called compact disc (CD) or a magneto-optical disc. 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 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 perpendicular to the optical axis of the objective lens is adjusted so that the position of the spot on the optical disk of the light beam emitted from the semiconductor laser follows the eccentricity of the optical disk or the meandering of the track formed on the optical disk. Is 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 an objective lens is attached, a plurality of elastic support members, and a driving 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 each coil, the magnetic flux generated in each coil interacts with the magnetic flux generated by the yoke 6 attached to the fixed portion 4 and the magnet 7 attached thereto.

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. Here, the end portion region of the elastic support member 5 on the fixed portion 4 side is configured as shown in FIGS. 7 and 8. 7 and 8, the elastic support member 5 has an end region 5a on the side of the fixed portion which is formed in a rectangular shape as a whole. Then, the end region 5a is
An elongated body portion 5b extending in the front-rear direction of the elastic support member 5
On the other hand, it has slits 5c and 5d provided on both sides thereof. In the end region 5a thus configured, the viscous body 8 is applied and cured on the end region 5a so as to straddle the main body portion 5b via the slits 5c and 5d. The viscous body 8 is, for example, an ultraviolet curable viscous body and is adapted to be cured by irradiating with ultraviolet rays after coating. As a result, the cured viscous body 8
However, by acting as a damper, the vibration of the main body portion 5b of the elastic support member 5 is suppressed.

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.

When the lens holder 2 is thus moved in the focusing direction and the tracking direction, the lens holder 2 tries to vibrate in the moving direction, but is provided near the rear end of the elastic support member 5. Vibration is suppressed by the damping action of the viscous body 8. As a result, the lens holder 2 is stopped in a stable state at the predetermined position.

[0011]

However, in the biaxial actuator 1 having such a configuration, the viscous body 8 has an uncured portion remaining on the surface due to oxygen inhibition when being cured by irradiation of ultraviolet rays or the like. It may happen. Then, such an uncured viscous body 8 flows to the peripheral portion of the fixed portion 4 and flows along the outsert line or the like, as shown in FIG. 7. As a result, the viscous body 8 flows into the bonding surface of the fixing portion 4, and particularly when the fixing portion 4 is formed by being divided into upper and lower parts and bonded to each other, the viscous body 8 flows into the upper and lower bonding surfaces to cause the bonding. There is a problem that the adhesive force is significantly reduced by reacting with the adhesive on the surface.

In view of the above points, the present invention ensures that the uncured portion of the damper provided on the elastic support member does not flow out to the adhesive surface of the fixing portion and is firmly fixed to the fixing portion. It is an object of the present invention to provide a biaxial actuator.

[0013]

According to the present invention, the above object is to provide a lens holder for supporting an objective lens, a fixing portion for supporting the lens holder via an elastic supporting member, and fixing of the elastic supporting member. A viscous body receiving portion provided in an end region on the side of the elastic body, the viscous body being applied as a damper, and the fixing portion is formed adjacent to the viscous body receiving portion of the elastic support member. This is achieved by a biaxial actuator that is provided with a viscous body flow prevention unit.

In the biaxial actuator according to the present invention, preferably, the viscous body flow prevention portion is formed integrally with the fixed portion.

In the biaxial actuator according to the present invention, preferably, the viscous body flow prevention portion is formed so as to extend beyond the peripheral edge of the elastic support member protruding from the fixed portion.

In the biaxial actuator according to the present invention, preferably, the elastic support member is outsert-molded with respect to the fixed portion.

In the biaxial actuator according to the present invention, preferably, the fixing portion and the lens holder are molded in a vertically divided state and assembled by an adhesive.

In the biaxial actuator according to the present invention, preferably, the fixing portion is directly or indirectly adhered to the base of the optical pickup.

[0019]

According to the above construction, the lens holder for holding the objective lens is supported by the elastic supporting member.
Then, 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.

At this time, the lens holder tries to vibrate in the moving direction, but the vibration is suppressed by the damping action of the viscous body provided as a damper in the end portion region of the elastic supporting member on the fixed portion side. become.

Here, the viscous body receiving portion, to which the viscous body is applied, is blocked by the viscous body flow preventing portion from the peripheral edge of the opposing fixed portion. Therefore, when the viscous body is cured, the uncured portion of the viscous body remaining due to oxygen inhibition tries to flow out to the peripheral edge of the fixed portion, but the flow of the viscous body is blocked by the viscous body flow prevention unit. It
As a result, the uncured portion of the viscous body does not reach the adhesive surface along the outsert line or parting line of the fixed portion.

When the viscous body flow prevention part is formed integrally with the fixed part, the viscous body flow prevention wall is formed at the same time when the fixed part is formed, so that the number of steps does not increase. The cost does not increase.

When the viscous body flow prevention portion is formed so as to extend beyond the peripheral edge of the elastic support member protruding from the fixed portion, it flows out from the viscous body receiving portion of the elastic support member. The uncured portion of the viscous body to be wraparound to the side of the fixed section is reliably prevented by the viscous body flow prevention section.

When the elastic support member is outsert-molded with respect to the fixed portion, the uncured portion of the viscous body is prevented from flowing along the outsert line generated in the fixed portion during molding. To be done.

In the case where the fixing part and the lens holder are molded in a vertically divided state and assembled by an adhesive, a viscous material is adhered along the boundary line between the upper part and the lower part of the fixing part. The uncured portion of the is prevented from flowing. Therefore, the adhesive strength of the adhesive surfaces of the upper and lower boundaries does not decrease.

When the fixing portion is directly or indirectly adhered to the base of the optical pickup, the uncured portion of the viscous material is adhered to the surface of the fixing portion adhered to the base. It is prevented from flowing. Accordingly, for example, when the fixed portion is formed by being divided into the upper and lower portions, the adhesive force of the adhesive surfaces of the upper and lower fixed portions does not decrease.

[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. The lens holder 11 is shown in FIG.
As shown in FIG. 5, it is preferably divided into an upper portion 11U and a lower portion 11L by a horizontal division line (parting line), and they are adhered to each other by an adhesive. Further, as shown in FIG. 3, the lens holder 11 is formed with an opening 11a to which the coil bobbin is attached and a recess 11b to which the objective lens 11c is attached. 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 side 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. The tracking coil 12c is formed by winding the coil into 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 may form a closed magnetic circuit together with the yoke portion of the magnetic circuit. The coil bobbin 12 includes the focusing coil 12b and the tracking coil 1.
2c is attached to the opening formed in the lens holder 11.

The elastic support members 13a, 13b, 13
It is preferable that c and 13d have electrical conductivity and spring properties, and materials such as phosphor bronze, beryllium copper, titanium copper, tin-nickel alloy, and stainless are 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. The fixing portion 14 is attached to the adjusting plate 30 in a state where the lens holder 11 and the fixing portion 14 are connected by the four elastic supporting members 13a, 13b, 13c, 13d. The adjusting plate 30 is for adjusting the fixing position of the fixing portion 14 when the biaxial actuator is assembled. The adjusting plate 30 is fixed to the base 31 formed integrally with the yoke by soldering or the like. To attach the fixing portion 14 to the adjusting plate 30, the boss provided on the fixing portion 14 is attached to the adjusting plate 3.
It is carried out by inserting it in the illustrated hole of 0 and fixing it with an adhesive or the like. Here, the base 31 has a pair of yokes 31a and 31b forming the magnetic circuit.
The permanent magnets 32 are provided by bending the ends on the objective lens side upward, and are attached to the surface of the one yoke 31a facing the other yoke 31b. As a result, the pair of yokes and the permanent magnet form a magnetic circuit. Then, as described above, when the fixing portion 14 is attached to the base, the focusing coil 12b and the tracking coil 12c attached to the coil bobbin 12 are inserted into the gap between the other yoke 31b and the permanent magnet 32. To be done. At the same time, the one yoke 31a and the permanent magnet 32 are
It will be inserted into the opening of the coil bobbin 12.

The elastic support members 13a, 13b, 13
c and 13d are end regions on the side of the fixed portion 14 in FIG.
And as shown in FIG. That is, in FIG. 4 and FIG. 5, the elastic support member 13a will be described. In the elastic support member 13a, the end region 15 on the side of the fixed portion 14 is formed in a square shape as a whole, for example, as illustrated. There is.

The end region 15 includes a fixed portion 15a fixed to the fixed portion 14, a movable portion 15b connected to the main body of the elastic support member 13a, and a rear edge portion of the fixed portion 15a (in the drawing). An elastic portion 15c extending from the vicinity of the right edge portion) in a crank shape and connected to the movable portion 15b, and the movable portion 15b.
Fixed portion 15a disposed behind the corner and having a corner portion 15d.
And a first viscous body receiving portion 15e connected to.

The movable portion 15b is formed relatively wide, and its surface serves as the second viscous body receiving portion.

Further, since the first viscous body receiving portion 15e is connected to the fixed portion 15a, it is fixed and held without being displaced during focusing or tracking, and is elastic with respect to the movable portion 15b. The support members 13a are formed to face each other with a slight gap 17 formed horizontally in a direction orthogonal to the extending direction of the support member 13a.

With respect to the first viscous body receiving portion 15e and the movable portion 15b, which is the second viscous body receiving portion, thus constructed, both viscous body receiving portions 15 straddle the gap 17.
The viscous body 16 is provided so as to connect the e and 15b. The viscous body 16 is, for example, an ultraviolet curable viscous body, and is stable with a substantially constant thickness in a state of being spread over the entire first viscous body receiving portion 15e and the second viscous body receiving portion 15b. become.

In this state, the viscous body 16 is cured by irradiating it with ultraviolet rays, and the cured viscous body 16 connects the first viscous body receiving portion 15e and the second viscous body receiving portion 15b. Will be.

On the other hand, as shown in FIGS. 2 and 4, the fixed portion 14 is provided with a viscous body flow prevention wall 14b at a portion adjacent to the end region 15 of the elastic support member 13a. The viscous body flow prevention wall 14 b is preferably formed integrally with the fixed portion 14. The viscous body flow prevention wall 14b is different from the peripheral edge 15f of the elastic support member 13a protruding from the fixed portion 14 with respect to the peripheral edge 15f.
It is formed so as to extend beyond.

Biaxial actuator 10 according to the present 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 or the objective lens 11c is driven in the focus direction Fcs and the tracking direction Trk by the alternating magnetic field generated by

Here, the elastic support member 1 is used as a damper.
In the end region 15 of the fixed portion 14 side of 3a, 13b, 13c, 13d, the viscous body 1 is arranged so as to straddle the gap 17 between the first viscous body receiving section 15e and the second viscous body receiving section 15b.
Since 6 has been applied and cured, the desired damping characteristics will be obtained. Thereby, for example, at the time of focusing, the second viscous body receiving portion 15b is deformed in the vertical direction with respect to the first viscous body receiving portion 15e, and the vibration due to the deformation is damped by the viscous body 16. Also,
At the time of tracking, the second viscous body receiving portion 15b is deformed so as to swing with respect to the first viscous body receiving portion 15e, and the vibration due to the deformation is damped by the viscous body 16.

Here, when the viscous body 16 is applied and cured, even if an uncured portion is generated on the surface of the viscous body 16 due to oxygen inhibition or the like, this uncured portion is the end region 15 of the elastic supporting member. It may flow out to the fixed portion 15a.
In particular, as in this embodiment, the lens holder 11 is
As shown in FIG. 3, the upper part 11U and the lower part 11L are divided by a horizontal dividing line (parting line), and when they are adhered to each other by an adhesive, the uncured body 16 is uncured along the parting line. It is conceivable that parts will flow. However, since the uncured portion of the viscous body is blocked by the viscous body flow prevention wall 14b formed in the fixed portion 14, it can flow out to the side edge 15f of the elastic support member located on the side of the fixed portion 14. There is no.

Therefore, the uncured portion of the viscous body 16 extends from the side edge 15f of the elastic supporting member on the side of the fixed portion 14 to the outsert line or parting line of the fixed portion 14, and further to the upper portion 11U and the lower portion 11L. Since it does not flow along the boundary, the adhesive surface 14b of the fixing portion 14, that is, the upper portion 11U
And does not flow into the bonding surface at the boundary of the lower portion 11L.
Thus, the adhesive strength of the adhesive surface is reduced, and the adhesive portion is prevented from falling off.

As described above, in the above-described embodiment, the viscous body receiving portion to which the viscous body is applied is blocked by the viscous body flow prevention wall to the side of the opposing fixed portion. Therefore, even if the uncured portion of the viscous body tries to flow out to the side of the fixed portion, the flow of the viscous body is blocked by the viscous body flow prevention wall. Thus, the viscous body does not flow into the bonding surface in the mutual bonding of the upper part and the lower part of the fixed part in the case of upper and lower division, and the adhesive force on this bonding surface does not decrease, and the bonding is ensured. Will be retained.

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.

[0045]

As described above, according to the present invention, the uncured portion of the damper provided on the elastic support member is prevented from flowing out to the adhesive surface of the fixing portion, and is firmly fixed to the fixing portion. It is possible to provide a biaxial actuator adapted to be fixed.

[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.

4 is an enlarged plan view showing an end region of the elastic support member on the fixed portion side in the biaxial actuator of FIG. 1. FIG.

5 is an enlarged side view showing an end region of the elastic support member on the fixed portion side in the biaxial actuator of FIG. 1. FIG.

FIG. 6 is a schematic perspective view showing an entire configuration of an example of a conventional biaxial actuator for an optical pickup.

7 is an enlarged plan view showing an end region of the elastic support member on the fixed portion side in the biaxial actuator of FIG.

8 is an enlarged side view showing an end region of the elastic support member on the fixed portion side in the biaxial actuator of FIG.

[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 Support Member 14 Fixing Part 14a Adhesive Surface 14b Viscous Flow Prevention Wall 15 end region 15a fixed part 15b movable part (second viscous body receiving part) 15c elastic part 15d corner 15e first viscous body receiving part 15f side edge 16 viscous body

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keiichi Shibata 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation

Claims (6)

[Claims] 1. A lens holder for supporting an objective lens, a fixing portion for supporting the lens holder via an elastic supporting member, and a viscous damper provided in an end region of the elastic supporting member on the fixing portion side. A viscous body receiving portion to which a body is applied, and further, the fixing portion is provided with a viscous body flow preventing portion formed adjacent to the viscous body receiving portion of the elastic supporting member. A characteristic biaxial actuator. 2. The biaxial actuator according to claim 1, wherein the viscous body flow prevention portion is formed integrally with the fixed portion. 3. The viscous body flow prevention part is formed so as to extend beyond the peripheral edge of the elastic support member with respect to the elastic support member protruding from the fixed part. Or the biaxial actuator according to 2. 4. The biaxial actuator according to claim 1, wherein the elastic support member is outsert-molded with respect to the fixed portion. 5. The fixed portion and the lens holder are
The biaxial actuator according to any one of claims 1 to 3, wherein the biaxial actuator is formed by being divided into upper and lower parts and assembled by an adhesive. 6. The biaxial actuator according to claim 1, wherein the fixing portion is directly or indirectly adhered to a base of the optical pickup.