JPH10124896A - Biaxial actuator and optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biaxial actuator specially preventing the generation of tangential skew among the tilts of the optical axis of an objective lens and improving the optical performance at the time of moving the lens in the focusing direction. SOLUTION: In a biaxial actuator, a fixed part 24 is vertically bisected, a spacer 29 capable of adjusting the height between the divided upper part 24U and the lower part 24L, the other ends of an upper and lower elastic supporting members 23a, 23b are fixed to the upper and lower parts, the interval between the fixing places of an elastic supporting member on the side of a lens holder is set so as to be narrower than the interval between the fixing places of an elastic supporting member provided oh the side of the fixing part and the interval between the fixing places of the elastic supporting member on the side of the fixing part is properly changed by adjusting the thickness of the spacer (d).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the recording and reproduction of information signals from optical disks (hereinafter, referred to as "optical disks") such as optical disks, magneto-optical disks, and phase-change disks, and information recording media for data storage. The present invention relates to a two-axis actuator for an optical pickup used to perform the operation, and an optical disk device using the same.

[0002]

2. Description of the Related Art Hitherto, reproduction or recording of information signals on an optical disk as a disk-shaped recording medium, for example, a so-called compact disk (CD) or a magneto-optical disk is performed using an optical pickup. This optical pickup has a semiconductor laser as a light source, an objective lens,
It includes 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 disk 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 disk in a direction orthogonal to the surface direction of the optical disk generated due to the warp of the optical disk or the like, so that it is focused on the recording surface of the optical disk, 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 adjustment of the spot position on the recording surface of the optical disk are adjusted by moving the objective lens in the optical axis direction of the objective lens and in the direction perpendicular to the optical axis. This 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 is driven by energizing a bobbin on which an objective lens is mounted and a plurality of coils are wound, a plurality of elastic supports, and a coil of the bobbin. A drive for generating a force. The bobbin is supported by a plurality of elastic support portions 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 with respect to the fixed portion. ing. Hereinafter, an example of this biaxial actuator is shown in FIG.
This will be described in Section 2.

[0005] Such a two-axis actuator is configured, for example, as shown in FIG. In FIG.
The biaxial actuator 1 includes a lens holder 2 with an objective lens 2a attached to the tip thereof, and a lens holder 2
And a coil bobbin (not shown) attached by bonding or the like.

The lens holder 2 has two ends perpendicular to the fixed part 3 by two pairs of wires 4 having one end on both sides of the lens holder 2 and the other end fixed to the fixed part 3. That is, the tracking direction perpendicular to the paper surface,
It is supported so as to be movable in a focus direction indicated by reference symbol Fcs.

The coil bobbin is wound with a focusing coil and a tracking coil (not shown). And by energizing each coil,
The magnetic flux generated in each coil interacts with the magnetic flux generated by the yoke (not shown) attached to the fixed portion 3 and the magnet attached thereto.

Further, the rear end of each of the wires 4 is soldered to the substrate 5 through the fixing portion 3. Here, as shown in FIG. 13, the wire 4 is fitted near the center of the damper 6 inserted into the through holes 3 a and 3 b of the fixing portion 3 in order to suppress the vibration of the wire 4. . In addition, in the case of FIG.
Are in contact with the substrate 5.

According to the biaxial actuator 1 configured as described above, when a driving voltage is supplied to each coil from the outside, the magnetic flux generated in each coil interacts with the magnetic flux generated by the yoke and the magnet. Then, the coil bobbin is moved in the tracking direction and the focus direction Fcs. Thus, the objective lens 2a attached to the lens holder 2 is appropriately moved in the focus direction and the tracking direction.

When the lens holder 2 is moved in the focusing direction and the tracking direction as described above, the lens holder 2 tends to vibrate in the moving direction, but a damper 6 provided near the rear end of the wire 4 is provided. The vibration is suppressed by the damping effect of the above. As a result, the lens holder 2 is stopped at a predetermined position in a stable state.

There is also known a two-axis actuator configured as shown in FIG. That is, in FIG. 14, the biaxial actuator 7 includes a lens holder 2 with an objective lens 2a attached to the tip thereof, and a coil bobbin (not shown) attached to the lens holder 2 by bonding or the like. I have.

The lens holder 2 is fixed to the fixing part 3 by at least one pair of leaf springs 8 having one end fixed to both sides of the lens holder 2 and the other end fixed to the fixing part 3.
Are supported so as to be movable in two directions perpendicular to the drawing, that is, in a tracking direction perpendicular to the paper surface and in a focus direction indicated by Fcs.

The coil bobbin is wound with a focus coil and a tracking coil (not shown). When a current is applied to each coil, a magnetic flux generated in each coil interacts with a magnetic flux generated by a yoke (not shown) attached to the fixed portion 3 and a magnet attached thereto.

In this case, as shown in FIG. 15, each of the leaf springs 8 has a crank portion 8a bent inwardly in the vicinity of the rear end thereof, and a frontward outward portion from the crank portion 8a. The extension 8b extends rearward and rearward, and has a protruding portion 8c that enters from the rear end of the leaf spring 8 between the crank portion 8a and the extension 8b. The protrusion 8c and the crank 8a
A slit 8e is set in the direction orthogonal to the optical axis direction of the objective lens 2a. An anti-vibration tape 9 is adhered as a damper so as to completely cover the crank portion 8a and the extension portion 8b, and the projection 8c and the slit 8e extending therebetween.

For this reason, when the lens holder 2 is moved in the focusing direction and the tracking direction, the lens holder 2 tends to vibrate in the moving direction, but is provided near the rear end of the leaf spring 8. Vibration tape 9
The vibration is suppressed by the damping action of. This allows
The lens holder 2 is stopped at a predetermined position in a stable state.

[0016]

However, in the biaxial actuator 7 having such a structure, there are the following problems when the lens holder 2 is moved in the focus direction. That is, FIG. 16 shows a state in which the len holder 2 is moved in the focus direction to move closer to the disk D, and FIG. 17 shows a state in which the ren holder 2 is moved in the focus direction to move away from the disk D.

In FIG. 16, when the lens holder 2 is brought close to the disk D, that is, when the arrow H
Are moved in the directions shown in FIG.
1, 8-2, the location of the slit 8e in FIG.
A force F1 is generated due to contraction or expansion in the X direction in FIG.
, A moment M1 (M1 = F1L) acts. For this reason,
As shown in FIG. 16B, the optical axis of the objective lens 2a is tilted, and a so-called plus-side tangential skew occurs.

Also, as shown in FIG. 17, the arrow I is moved so that the lens holder 2 is moved away from the disk D in the opposite direction.
When the focusing movement is performed in the direction of, the slit 8e in FIG. 15 shrinks or expands in the X direction in FIG. 17 between the upper and lower springs 8-1 and 8-2 in FIG. F2 is generated, and a moment M2 (M2 = F2L) acts on the lens holder 2 in relation to the distance L. Also in this case, as shown in FIG. 17B, the optical axis of the objective lens 2a is tilted, and so-called negative tangential skew occurs.

For this reason, the biaxial actuator 7 has a problem that the optical performance such as the signal reading performance of the optical pickup deteriorates due to the occurrence of the so-called dynamic skew which is the inclination of the optical axis of the objective lens 2. . In particular, among the dynamic skews, the above-described tangential skew has a small tolerance in performing accurate signal reading and the like, and thus it has been desired to prevent occurrence of the tangential skew.

In view of the above, the present invention has been made to improve the optical performance by preventing the occurrence of tangential skew, particularly when the optical axis of the objective lens is tilted, when moved in the focus direction. It is intended to provide a shaft actuator.

[0021]

According to the present invention, there is provided a lens holder for supporting an objective lens, wherein one end is fixed to the lens holder and the other end is fixed to a fixing portion. A pair of elastic support members, and a driving unit for moving the lens holder in a biaxial direction with respect to the fixed portion, wherein the elastic support members are elastically moved along the direction in which the elastic support members extend. The fixed portion is vertically divided into two, and a height-adjustable spacer is disposed between the divided upper and lower portions. , The other ends of the upper and lower elastic support members are fixed,
This is achieved by a biaxial actuator in which the vertical spacing between the fixed portions of the elastic support member on the lens holder side is set to be smaller than the vertical space between the fixed portions of the elastic support member provided on the fixed portion side. You.

According to the above configuration, the pair of elastic members arranged in the optical axis direction of the objective lens are spaced apart from each other in the vertical direction.
It is narrower on the lens holder side and wider on the fixed part side, and the vertical spacing of the fixed position on the fixed part side can be arbitrarily changed by adjusting the height of the spacer. With this structure, when the lens holder is moved in the optical axis direction, that is, in the so-called focus direction, when the lens holder is brought close to the disc-shaped recording medium, the negative tangential skew is moved away from the disc-shaped recording medium. In this case, the biaxial actuator is given such a behavior characteristic that a tangential skew on the plus side is generated.

Since such behavioral characteristics are opposite to the behavioral characteristics caused by providing the elastic supporting member with the expansion and contraction portions, by appropriately adjusting the height of the spacer, the contradictory characteristics can be completely eliminated. Therefore, the optical axis of the objective lens does not fall during the focusing movement. Therefore, since the optical axis of the objective lens does not tilt due to the movement of the biaxial actuator in the tracking direction, dynamic skew in the tangential direction does not occur, and optical characteristics such as signal reading characteristics of the optical pickup are reduced. Will be improved.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS.
The embodiment described below is a preferred specific example of the present invention, and thus various technically preferable limitations are added. 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.

FIG. 1 shows an embodiment of an optical disk device incorporating a biaxial actuator according to the present invention. In FIG. 1, an optical disk device 10 includes a spindle motor 12 as a driving means for rotatingly driving an optical disk 11, and a signal recording surface of the rotating optical disk 11 which is irradiated with a light beam to record a signal. An optical pickup 19a for reproducing a recording signal by a return light beam from the optical pickup and a control unit 13 for controlling these. Here, the control unit 13 controls the optical disc controller 1
4, signal demodulator 15, error correction circuit 16, interface 17, head access control unit 18, and servo circuit 1
9 is provided.

The optical disk controller 14 controls the drive of the spindle motor 12 at a predetermined rotation speed. The signal demodulator 15 demodulates the recording signal from the optical pickup 19a, corrects the error, and sends the signal to an external computer or the like via the interface 17. Thus, an external computer or the like can receive a signal recorded on the optical disk 11 as a reproduction signal.

The head access control unit 18 moves the optical pickup 19a to a predetermined recording track on the optical disk 11, for example, by a track jump or the like. At the moved predetermined position, the servo circuit 19 moves the objective lens held by the biaxial actuator of the optical pickup 19a in the focus direction and the tracking direction.

FIGS. 2 to 4 show the optical disk device 10.
2 shows the configuration of the two-axis actuator. FIG.
4 to 4, the biaxial actuator 20 includes a lens holder 21, a coil bobbin 22, a plurality of elastic support members 23a, 23b, 23c, 23d, a fixing portion 24, and a yoke 31.

In the present embodiment, the lens holder 21 is preferably divided into an upper part 21U and a lower part 21L by a horizontal dividing line (parting line) as shown in FIG. Or bonded together by an adhesive. Further, as shown in FIG. 4, the lens holder 21 has an opening 21a to which a coil bobbin is attached, and a recess 21b to which an objective lens 21c is attached. A hole through which a light beam emitted from the semiconductor laser or a return light beam from the recording surface of the optical disk passes is formed on the bottom surface of the concave portion 21b. The objective lens 21c is attached to the concave portion 21b of the lens holder 21 by bonding or the like.

Further, the lens holder 21 is supported by elastic support members 23a, 23b, 23c and 23d so as to be movable in the focus direction Fcs and the tracking direction Trk.

The coil bobbin 22 has an opening 22a into which a magnetic circuit consisting of a yoke 31 integral with the base and a magnet 32 attached to the inner surface of the inner yoke 31a is inserted.
2b and a tracking coil 22c are provided. The focusing coil 22b is wound around the coil bobbin 22 along an axis parallel to the optical axis of the objective lens 21c. The tracking coil 22c is formed by winding the coil in an elliptical or rectangular shape, and is attached to one side surface of the focusing coil 22b. The upper surface of the coil bobbin 22 is covered by a yoke bridge 36. This yoke bridge 3
6 may constitute a closed magnetic circuit together with the yoke portion of the magnetic circuit. The coil bobbin 22 is attached to an opening formed in the lens holder 21 with the focusing coil 22b and the tracking coil 22c attached.

The elastic support members 23a, 23b, 23
It is preferable that c and 23d have conductivity and also have spring properties. For example, phosphor bronze, beryllium copper, titanium copper, tin-nickel alloy, stainless steel, or the like is used. Thus, in the present embodiment, for example, a leaf spring suspension is formed by a thin sheet metal, and is fixed between the lens holder 21 and the fixing portion 24 in a non-parallel manner.

FIG. 7 shows the elastic support members 23a and 23b.
Is a view schematically showing the fixing structure of the first embodiment. Elastic support members 23c and 23d provided on the side surface on the opposite side have the same configuration. One end of each of the elastic support members 23a and 23b is fixed to the fixed portion 41,
At 42, it is fixed. These elastic support members 23
a and 23b are fixed to the fixing portion 24 at the fixing point 4
It is fixed at 3,44. As a result, the elastic support members 23a and 23b are paired in the optical axis direction of the objective lens 21c, and form a pair.
4 is fixed to the side surface.

The distance h1 between the fixed portions 41 and 42 on the lens holder side of the elastic support members 23a and 23b is smaller than the distance h2 between the fixed portions 43 and 44 on the fixed portion 24. Elastic support members 23a, 23b
Is extended toward the front end side of the lens holder 21 (to the left in the figure), these virtual extension lines intersect at a certain point P as shown by a dotted line. still,
These elastic support members 23a, 23b, 23c, 23d
Represents a drive current from an external current supply unit (not shown),
Focusing coil 22 wound around the coil bobbin 22
b and the tracking coil 22c.

With the lens holder 21 and the fixing portion 24 connected by four elastic support members 23a, 23b, 23c and 23d, the fixing portion 24 is attached to the adjustment plate 30 of FIG. This adjustment plate 30
Is for adjusting the fixing position of the fixing portion 24 at the time of assembling the biaxial actuator. And adjustment plate 3
0 is relative to the base 31 formed integrally with the yoke.
It is fixed by soldering or the like. The fixing portion 24 is attached to the adjustment plate 30 by inserting a boss provided on the fixing portion 24 into a hole shown in the adjustment plate 30 and fixing it with an adhesive or the like.

Here, a pair of yokes 31a and 31b constituting the magnetic circuit are provided on the base 31 by bending the ends of the base 31 on the objective lens side upward, respectively. A permanent magnet 32 is provided on the surface of the base 31a facing the other yoke 31b. Thus, a magnetic circuit is constituted by the pair of yokes and the permanent magnet. Then, as described above, when the fixing portion 24 is attached to the base, the focusing coil 22 attached to the coil bobbin 22 is inserted into the gap between the other yoke 31b and the permanent magnet 32.
b and the tracking coil 22c are inserted. At the same time, the one yoke 31a and the permanent magnet 32 are inserted into the opening of the coil bobbin 22.

The elastic support members 23a, 23b, 23
c and 23d are in the end region on the fixed portion 24 side,
The configuration is as shown in FIGS. 5 and 6. That is, the elastic support member 23a will be described with reference to FIGS. 5 and 6. The elastic support member 23a has an end region 25 on the fixing portion 24 side formed as a whole as shown in FIG. I have.

The end region 25 includes an immovable portion 25a as a first portion fixed to the fixed portion 24 and a movable portion 25b as a second portion connected to the main body of the elastic support member 23a. Have. The elastic portion 2 as a third portion extends in a crank shape from the vicinity of the rear edge (right edge in the drawing) of the fixed portion 25a and is connected to the movable portion 25b.
5c and a corner 2 disposed behind the movable portion 25b.
And a first viscous body receiving portion 25e connected to the immovable portion 25a via 5d. The movable section 25b is formed relatively wide, and the surface thereof is configured as a second viscous body receiving section.

Since the first viscous body receiving portion 25e is connected to the immovable portion 25a, the first viscous body receiving portion 25e is fixed and held without being displaced at the time of focusing or tracking, and is elastically movable with respect to the movable portion 25b. The support members 23a are formed so as to face each other across a slight gap 27 formed horizontally in a direction perpendicular to the direction in which the support members 23a extend. A gap 25k is formed between the stationary part 25a and the elastic part 25c in a direction orthogonal to the direction in which the elastic support member 23a extends, and a gap is formed between the elastic part 25c and the first viscous body receiving part 25e. 25 l are provided. These gaps 27,
25k and 25l, together with the elastic portion 25c, constitute a telescopic portion 28 that expands and contracts within the width of each gap when the lens holder 21 is moved in the focussing direction Fcs.

With respect to the first viscous body receiving portion 25e and the movable portion 25b as the second viscous body receiving portion, both viscous body receiving portions 25 are straddled over the gap 27.
A viscous body 26 is provided so as to connect e and 25b. The viscous body 26 is, for example, an ultraviolet curable viscous body, and is stable at a substantially constant thickness in a state where the viscous body 26 is spread over the entire first viscous body receiving portion 25e and the second viscous body receiving portion 25b. become.

In this state, the viscous body 26 is cured by irradiating ultraviolet rays, and the first viscous body receiving portion 25e and the second viscous body receiving portion 25b are connected by the cured viscous body 26. Will be.

On the other hand, as shown in FIGS. 3 and 5, the fixing portion 24 is provided with a viscous body flow preventing wall 24b at a portion adjacent to the end region 25 of the elastic support member 23a. This viscous body flow prevention wall 24b is preferably formed integrally with the fixed portion 24. The viscous body flow prevention wall 24b is provided on the periphery 25f of the elastic support member 23a protruding from the fixing portion 24.
It is formed to extend beyond.

Further, the fixing portion 24 is provided in the positions shown in FIGS.
As shown in the figure, similarly to the lens holder 21, the upper part 24U is divided by a horizontal dividing line (parting line).
And a lower portion 24L.
A spacer 29 is interposed between the 4U and the lower portion 24L, and is connected to each other by press-fitting or bonded to each other by an adhesive. The upper elastic support members 23a and 23c are fixed to the upper portion 24U of the fixed portion 24, and the lower elastic support members 23b and 23d are fixed to the lower portion 24L of the fixed portion 24, respectively.

Here, as shown in FIG. 10, the spacer 29 is formed integrally with the upper portion 24U of the fixed portion 24, and is configured so that its thickness d can be adjusted.
The thickness d of the spacer 29 is the upper portion 24U of the fixed portion 24.
In the metal mold for forming the spacer 29, an appropriate thickness is selected by incorporating a variable mechanism into a portion where the spacer 29 is formed. In the case shown,
The spacer 29 is formed integrally with the upper portion 24U of the fixing portion 24, but is not limited thereto, and may be formed integrally with the lower portion 24L of the fixing portion 24, or may be formed separately. , May be interposed between the upper portion 24U and the lower portion 24L of the fixing portion 24.

The biaxial actuator 20 according to the present embodiment
The optical disk device 10 incorporating the above is configured as described above, and operates as follows when reproducing the optical disk 11. When the spindle motor 12 of the optical disk device 10 rotates, the optical disk 11 is driven to rotate. Then, by moving the optical pickup 13 in the radial direction of the optical disc 11, the optical axis of the objective lens 21a is moved to a desired track position of the optical disc 11 to perform access.

In this state, the light beam from the semiconductor laser element, which is a light source, is formed on the signal recording surface of the optical disk 11 by the optical pickup 13 via the objective lens 21a. The return light from the optical disk 11 forms an image again on the photodetector via the objective lens 21a. Thereby, based on the detection signal of the photodetector, the optical disk 11
Is reproduced.

At this time, a tracking error signal and a focus signal are detected by the signal demodulator 15 from the detection signal from the photodetector, and the servo circuit 19 controls the focus coil 24 and the tracking coil via the optical disk drive controller 14. The servo control of the drive voltage to the use coil 25 is performed. Thereby, each focusing coil 25
, The lens holder 21 is moved and adjusted in the focus direction Fcs against the tension of the elastic support member 23, and focusing is performed. Further, by controlling the drive voltage of each tracking coil 25, the lens holder 21
The tracking is performed by adjusting the movement in the tracking direction Trk against the tension of.

Then, in the biaxial actuator 20 of the present embodiment, when the lens holder 21 is driven in the focus direction Fcs, a behavior characteristic as shown in FIG. 8 is provided. FIG. 8 is a principle diagram for explaining the behavior characteristics of the lens holder 21. In the figure, an electromagnetic driving force acts on the lens holder 21 to approach the disk 11 in a direction indicated by an arrow H, that is, a focus direction. Consider the case where force is applied to the direction.

In this case, the elastic support members 23a, 23
One end of b is attached to the lens holder 21 as described above in 41, 4
2 and the other end side is a fixing portion 24
The elastic support members 23a and 23b do not expand and contract. here,
The angle formed between the elastic support member 23a and the vertical front surface of the fixing portion 24 is α. When the elastic support member 23a is horizontal in the figure, the length of the elastic support member 23a does not change. Therefore, the fixing portion 41 on the lens holder 21 side is located at the position farthest from the fixing portion 24. Go to In this state, the angle between the elastic support member 23a and the vertical front surface of the fixing portion 24 is defined as θ.

When the lens holder 21 is moved for focusing so as to move toward the disk 11, the elastic support member 23a moves to a position shown by a chain line.
At this time, the angle α formed by the vertical front surface of the elastic support member 23a and the fixing portion 24 gradually approaches θ, so that the fixing portion 41 gradually moves away from the fixing portion 24 while moving upward in the drawing. . On the other hand, the elastic support member 23b
When the lens holder 21 receives a force in the direction of the arrow H,
The angle β formed by the vertical front surface of the elastic support member 23b and the fixed portion 24 becomes smaller, and the difference from θ becomes larger. For this reason, as shown in the figure, the fixed portion 42 of the elastic support member 23b on the lens holder side gradually moves upward,
The distance from the fixing portion 24 gradually decreases.

Thus, if the elastic support members 23a and 23b do not expand and contract, the fixing points 41 and 42 of the elastic support members 23a and 23b on the lens holder side follow the arc-shaped locus J about the point P. Therefore, the lens holder 21 is provided with a characteristic of generating a tangential skew on the minus side. Conversely, if the lens holder 21 is moved in the focus direction so as to move away from the optical disc D (downward in the figure), the lens holder 21
Has the property of generating a positive tangential skew.

On the other hand, the elastic support members 23a, 23
b has an elastic portion 28 as described with reference to FIG. 5, and when the elastic support member has such an elastic function, as described with reference to FIGS. The reverse behavior characteristic is given to the lens holder 21. As a result, the biaxial actuator 20 of the present embodiment includes the fixing portions 41 of the elastic support members 23a, 23b, 23c, 23d.
By adopting a configuration in which 42, 43, and 44 are changed as described above, even when the telescopic unit 28 is provided, the tangential skew that occurs due to the respective configurations is opposite, and thus these characteristics are reduced. They will cancel each other out.

Here, since the spacer 29 is provided between the upper portion 24U and the lower portion 24L of the fixing portion 24, the thickness d of the spacer 29 is appropriately adjusted, so that the above-described characteristics can be obtained. , The tangential skew is completely canceled out, and the lens holder 21 is moved to the position shown in FIG.
As shown by 0, the objective lens 21c is moved in parallel without causing the optical axis to tilt. Thus, in the biaxial actuator of the present embodiment, in order to satisfy the signal reading performance of the optical pickup, the tangential skew with an extremely low tolerance can be reliably eliminated, and excellent optical performance can be exhibited. .

Further, in the biaxial actuator 20 of this embodiment, the following advantageous effects can be further exhibited by providing the expansion / contraction portion 28. That is, the elastic support members 23a, 23b, 23c, 23 serve as dampers.
In the end region 25 on the fixing portion 24 side of d, the viscous body 26 is applied and cured so as to straddle the gap 27 between the first viscous body receiving portion 25e and the second viscous body receiving portion 25b. Therefore, desired damping characteristics can be obtained.
Thereby, for example, at the time of focusing, the second viscous body receiving portion 25b is vertically deformed with respect to the first viscous body receiving portion 25e, and the vibration due to the deformation is attenuated by the viscous body 26. Further, at the time of tracking, the second viscous body receiving portion 25b is deformed so as to swing with respect to the first viscous body receiving portion 25e, and the vibration due to the deformation is
Attenuated by viscous body 26.

Here, when the viscous material 26 is applied and cured, even if an uncured portion is generated on the surface of the viscous material 26 due to oxygen inhibition or the like, the uncured portion remains in the end region 25 of the elastic support member. It may flow out to the immovable part 25a.
Particularly, as shown in FIG. 4, the lens holder 21 is divided into an upper part 21U and a lower part 21L by a horizontal dividing line (parting line) as shown in FIG. If so, the uncured portion of the viscous body 26 may flow along the parting line. However, since the uncured portion of the viscous body is blocked by the viscous body flow prevention wall 24b formed on the fixed portion 24, the uncured portion flows out to the side edge 25f of the elastic support member located on the side of the fixed portion 24. There is no.

Therefore, from the side edge 25f of the elastic support member on the side of the fixing portion 24, the uncured portion of the viscous body 26 is formed by the outsert line and parting line of the fixing portion 24 and the upper 21U and lower 21L. Since it does not flow along the boundary, the bonding surface 24b of the fixing portion 24, that is,
It does not flow into the bonding surface at the boundary between the lower portion and the lower portion 21L.
Thus, the adhesive strength of the adhesive surface is reduced, so that the adhesive portion is prevented from falling off.

The two-axis actuator 20 is mounted on the upper portion 2 of the lens holder 21 and the fixing portion 24 during assembly.
When the 1U, 24U and the lower portions 21L, 24L are pressed against each other by the press-fit head, the height of the fixing portion 24 is different from the height of the lens holder 21 because the spacer 29 is interposed in the fixing portion 24. So
As shown in FIG. 11, the press-fitting is performed simultaneously by using the press-fitting head 45 for the lens holder 21 and the press-fitting head 46 for the fixing part 24, respectively.

In the above-described embodiment, the elastic support members 23a, 23b, 23c, and 23d have been described as being simply fixed to the lens holder 21 and the fixing portion 24, respectively. Obviously, the fixing part 24 may be integrally formed by insert formation or the like. In addition, lens holder 2
1 is divided into an upper part 21U and a lower part 21L,
Obviously, they may be integrally formed.

[0059]

As described above, according to the present invention, it is possible to prevent the occurrence of tangential skew in the tilt of the optical axis of the objective lens when moving in the focus direction, and to improve the optical performance. Thus, a two-axis actuator can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing the configuration of an optical disc device incorporating one embodiment of a biaxial actuator according to the present invention.

FIG. 2 is a schematic perspective view showing the overall configuration of a biaxial actuator in the optical disk device of FIG. 1 as viewed from the front.

FIG. 3 is a schematic perspective view showing a state where the biaxial actuator of FIG. 2 is viewed from the rear.

FIG. 4 is an exploded perspective view of the biaxial actuator of FIG. 2;

FIG. 5 is an enlarged plan view showing an end region on the fixed portion side of the elastic support member in the biaxial actuator of FIG. 2;

FIG. 6 is an enlarged side view showing an end region on the fixed portion side of the elastic support member in the biaxial actuator of FIG. 2;

FIG. 7 is a schematic side view showing a structure for fixing an elastic support member of the biaxial actuator of FIG. 2;

FIG. 8 is a principle diagram for explaining behavior characteristics of the biaxial actuator of FIG. 7;

FIG. 9 is a schematic diagram illustrating behavior characteristics of the biaxial actuator of FIG. 2;

FIG. 10 is a partially enlarged view showing a relationship between a fixed portion and a spacer in the biaxial actuator of FIG. 2;

FIG. 11 is a schematic diagram showing a press-fit state of a lens holder and a fixing part in the biaxial actuator of FIG. 2;

FIG. 12 is a schematic side view showing an example of a conventional biaxial actuator.

13 is a partial side sectional view showing a fixing portion of an elastic support member of the biaxial actuator of FIG.

FIG. 14 is a partial plan view of the biaxial actuator of FIG.

FIG. 15 is an enlarged perspective view showing an end of the elastic support member of the biaxial actuator of FIG. 12 on the fixed portion side.

FIG. 16 is a schematic diagram showing behavior characteristics of a conventional two-axis actuator during focusing movement.

FIG. 17 is a schematic diagram showing behavior characteristics of a conventional two-axis actuator during focusing movement.

[Explanation of symbols]

10 optical disk device, 11 optical disk, 1
2 ... Spindle motor, 13 ... Optical pickup, 14 ... Optical disk drive controller, 15
... Signal demodulator, 16 ... Error correction circuit, 17 ...
Interface, 18 Head access control unit, 19 Servo circuit, 20 Biaxial actuator, 21 Lens holder, 21c Objective lens, 22 Coil bobbin, 23a, 23b , 23
c, 23d: elastic support member, 24: fixed portion, 2
4U: upper part, 24L: lower part, 25: end area, 26: viscous body, 27: gap, 28: elastic part, 29: spacer, 30 ... Adjustment plate,
31 ... yoke, 32 ... magnet, 36 ...
Yoke bridge, 41, 42, 43, 44 ... fixed parts.

Claims (4)

[Claims] 1. A lens holder for supporting an objective lens, two pairs of elastic support members, one end of which is fixed to the lens holder and the other end of which is fixed to a fixing part; Driving means for moving the elastic supporting member in two axial directions, the elastic supporting member further includes an elastic portion that elastically slightly expands and contracts along a direction in which the elastic supporting member extends, , Is divided into upper and lower, and a height adjustable spacer is disposed between the divided upper and lower parts,
The other ends of the upper and lower elastic support members are fixed to the upper and lower portions, respectively, and the upper and lower spaces of the fixing portion of the elastic support member on the lens holder side are provided on the fixed portion side. A two-axis actuator characterized in that it is set so as to be narrower than an upper and lower interval of a fixing portion of a member. 2. The biaxial actuator according to claim 1, wherein the spacer is formed separately from the fixed part, and is interposed between an upper part and a lower part of the fixed part. 3. The spacer is formed integrally with an upper portion or a lower portion of a fixed portion in a molding die, and a variable mechanism for adjusting the height of the spacer is incorporated in the molding die. The biaxial actuator according to claim 1, wherein 4. A driving means for rotating and driving an optical disc, and irradiating the rotating optical disc with light via an objective lens, and detecting a return light from a signal recording surface of the optical disc by a photodetector via the objective lens. Optical pickup, a biaxial actuator for supporting an objective lens movably in two axial directions, a signal processing circuit for generating a reproduction signal based on a detection signal from the photodetector, and a detection signal from the photodetector A servo circuit for moving the objective lens of the optical pickup in two axial directions based on the above, wherein the biaxial actuator has a lens holder supporting the objective lens, one end of which is fixed to the lens holder, and the other end of which is fixed to the lens holder. Including two pairs of elastic support members fixed to the fixed portion, and driving means for moving the lens holder in two axial directions with respect to the fixed portion. The elastic support member further includes an elastic portion that elastically slightly expands and contracts along a direction in which the elastic support member extends. The fixed portion is divided into upper and lower portions, and the upper and lower portions are divided. There is a height adjustable spacer between them,
The other ends of the upper and lower elastic support members are fixed to the upper and lower portions, respectively, and the upper and lower spaces of the fixing portion of the elastic support member on the lens holder side are provided on the fixed portion side. An optical disc device characterized in that it is set so as to be narrower than an upper and lower interval of a fixing portion of a member.