JPH04325930A - Objective lens drive device - Google Patents

Abstract

PURPOSE:To provide the objective lens drive device having thin structure and stable supporting and driving characteristics. CONSTITUTION:Parallel leaf springs 5 having torsion center parts 5a and circular tracking supporting parts 5b arranged radially around the torsion center parts 5a crimp a movable part at the torsion center parts 5a from the direction of a centroid axis K, support it movably in a focusing direction F and support it rotatably around the centroid axis K for the movable part, and the position relation among eight interlocked parts 5d is relatively maintained by a frame member 6. Since the eight interlocked parts 5d are fixed by the frame member 6 and the position relation among the eight interlocked parts 5d is relatively maintained displacing frequency response characteristic is not degraded in the focus direction F and a tracking direction T.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens driving device for an apparatus for optically recording or reproducing information on a disk-shaped recording medium.

0002

2. Description of the Related Art An objective lens driving device is used to drive an objective lens with a beam perpendicular to the surface of the recording medium in order to correct a focus shift caused by vertical movement of a warped disk-shaped recording medium such as a compact disk, and a tracking shift caused by eccentricity. The axial direction (hereinafter referred to as focus direction F) and the radial direction parallel to the recording medium surface (hereinafter referred to as tracking direction T)
It is driven by two axes.

An example of a conventional objective lens driving device will be described below with reference to the drawings. FIG. 7 is a perspective view showing the configuration of a conventional objective lens driving device.

In FIG. 7, F is a focusing direction, T is a tracking direction, 101 is an objective lens, 102 is a lens holder to which the objective lens 101 is attached, 103 is an intermediate member, 104 is a fixing member, and 105 is attached to the intermediate member 10 at one end.
3. Parallel plate spring for tracking that supports the lens holder 102 movably in the tracking direction T by fixing one end to the lens holder 102; A parallel plate spring for focusing that supports the lens holder 102 movably in the focus direction F via the member 103; 107 is a focusing coil fixed to the lens holder 102; 108a and 108b are tracking coils fixed to the lens holder 102; 109a,1
09b is a driving magnet fixed to the fixing member 104 at a position facing the focusing coil 107 and the tracking coils 108a, 108b.

The operation of the objective lens driving device constructed as described above will be explained below.

First, in driving in the focus direction F, the focusing coil 107 fixed to the lens holder 102 to which the objective lens 101 is attached is driven by the driving magnet 10.
9a and 109b, the lens holder 102 constitutes an intermediate member 103 and a parallel plate spring 105 for tracking, and is supported by a parallel plate spring 106 for focusing, so that the lens holder 102 moves in the focusing direction F. It is obtained by translational movement to . Further, driving in the tracking direction T is performed using an electromagnetic force obtained when the tracking coils 108a and 108b fixed to the lens holder 102 to which the objective lens 101 is attached are perpendicular to the magnetic flux generated by the driving magnets 109a and 109b. Receptacle, lens holder 1
02 is supported at one end by a tracking parallel plate spring 105 fixed to the intermediate member 103, and is obtained by translationally moving in the tracking direction T.

[0007]

[Problems to be Solved by the Invention] However, in the above configuration, since the tracking parallel plate spring 105 is arranged on a plane substantially parallel to the optical axis of the objective lens 101, it hinders thinning in the focus direction F. This was a contributing factor.

Further, the structure of the support mechanism is complicated and the number of parts is large, which increases the number of assembly steps, which is one of the factors that hinders cost reduction.

Further, in the focusing direction F, the lens holder 102 is connected to the focusing parallel plate spring 1 via the intermediate member 103 and the tracking parallel plate spring 105.
06, and the driving center of gravity position cannot be made to coincide with the support point. Therefore, when the objective lens 101 is driven in the focus direction F, the lens holder 102 tends to rotate around an axis parallel to the tracking direction T. Therefore, there was a problem that the displacement frequency response characteristics in the focus direction F were deteriorated.

In view of the above-mentioned problems, the present invention makes it possible to reduce the thickness of the device by providing support in the tracking direction T using a plate spring disposed in a plane perpendicular to the focus direction F, and also to support the tracking direction T and provide support in the tracking direction T. Support in the focusing direction F is also provided by an integrally formed leaf spring, reducing the number of parts and simplifying the support mechanism, thereby realizing cost reduction. By providing a means for relatively maintaining the positional relationship of the surfaces, it is possible to prevent the leaf spring from flapping, and to maintain the center of rotation of the lens holder in the tracking direction T, the support position in the focus direction F, and the approximate center of gravity of the lens holder. By matching these, stable support can be achieved that can prevent rotation of the lens holder around an axis parallel to the tracking direction T and rotation around an axis parallel to the tangential direction of the disk-shaped recording medium during driving in the focus direction F. and an objective lens driving device that realizes driving.

[0011]

[Means for Solving the Problems] In order to solve the above problems, the objective lens driving device of the present invention includes a twisting center portion that clamps the movable portion from an axial direction that passes through the center of gravity and is approximately parallel to the optical axis of the objective lens; and a plurality of tracking supports having one or more bent parts formed radially around the torsion center, and the movable part can be moved in the optical axis direction via the torsion center and the plurality of tracking supports. A parallel plate spring consisting of a focusing support part supported by a parallel plate spring arranged in parallel, and a plurality of linking parts between the focusing support part and the tracking support part of the parallel plate spring are compared relative to each other. a fixing member for fixing one end of the focusing support portion of the parallel leaf spring; a tracking drive means for moving the objective lens in a radial direction parallel to the disk-shaped recording medium; and a tracking drive means for moving the objective lens in the optical axis direction. and a focusing drive means.

0012

[Operation] With this configuration, the lens holder is rotated around an axis approximately parallel to the optical axis of the objective lens by the extension of the tracking support portion having a bent portion of a parallel plate spring arranged in a plane perpendicular to the focus direction F. This makes it possible to support the device as easily as possible, making it possible to make the device thinner.

Furthermore, since the integrally formed leaf spring can serve both as support in the tracking direction T and support in the focusing direction F, costs can be reduced by reducing the number of parts and simplifying the support mechanism.

Furthermore, a means for relatively maintaining the positional relationship between the two surfaces of the parallel plate spring having the tracking support portion is provided to prevent the plate spring from fluttering, and to maintain the center of rotation of the lens holder in the tracking direction T and the focus direction F. By aligning the support position of the lens holder with the approximate center of gravity of the lens holder, rotation of the lens holder around an axis parallel to the tracking direction T and an axis parallel to the tangential direction of the disc-shaped recording medium during driving in the focus direction F can be achieved. Stable support and drive that can prevent rotation can be achieved.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An objective lens driving device according to a first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing the configuration of an objective lens driving device according to a first embodiment of the present invention, and FIG. 2 is an exploded perspective view showing the configuration of an objective lens driving device according to the first embodiment. 3 is a plan view showing the operation of the objective lens driving device of the first embodiment in the tracking direction.

In FIGS. 1, 2 and 3, F is a focus direction, T is a tracking direction, 1 is an objective lens,
2 is a lens holder that holds the objective lens 1, 3 is a balance member, 4a and 4b are permanent magnets fixed to the lens holder, and K is composed of the objective lens 1, lens holder 2, balance member 3, and permanent magnets 4a and 4b. The center axis 5 passes through the approximate center of gravity of the movable part and is approximately parallel to the optical axis of the objective lens 1, and has a torsion center part 5a and an elliptical tracking support part 5b arranged radially around the torsion center part 5a. and a focusing support that supports the movable part so as to be movable in a direction substantially parallel to the center of gravity K via the twist center 5a and the tracking support part 5b by sandwiching the movable part between the twist centers 5a from the direction of the center of gravity axis K. A pair of parallel plate springs having portions 5c, 5d a linking portion between the tracking support portion 5b and the focusing support portion 5c of the parallel plate spring 5, 6 fixing the eight linking portions 5d, and numeral 6 fixing the eight linking portions 5d. Frame members 7a and 7b that relatively maintain the positional relationship of
8a, 8b are wound around the opposing yokes 7a, 7b, and the objective lens 1 is moved in the focus direction F by the permanent magnets 4a, 4b.
Focusing coils 9a and 9b are wound around opposing yokes 7a and 7b to drive the objective lens 1 in the tracking direction T by permanent magnets 4a and 4b; 10 is a tracking coil that fixes one end of the parallel plate spring 5; A base/coupling yoke 11 fixes the opposing yokes 7a and 7b, and an auxiliary yoke 11 is fixed to the base/coupling yoke 9.

The operation of the objective lens driving device constructed as described above will be explained below.

First, the objective lens 1 is driven in the focus direction F by the electromagnetic action of the focus coils 8a, 8b wound around the opposing yokes 7a, 7b and the permanent magnets 4a, 4b attached to the lens holder 2. Parallel leaf spring 5
This is achieved by the lens holder 2 being translated in the focus direction F by the bending of the focusing support portion 5c, and the objective lens 1 being driven in the focus direction F.

Furthermore, the tracking direction T of the objective lens 1
is driven by the electromagnetic action of the tracking coils 9a, 9b wound around the facing yokes 7a, 7b and the permanent magnets 4a, 4b attached to the lens holder 2, so that the lens holder 2 rotates in the direction of rotation around the center axis K. As shown in FIG. 3, as shown in FIG. Obtained by being driven.

As described above, according to the embodiment of the present invention, the movable part is is held between the torsion center portions 5a from the direction of the center of gravity axis K, supported movably in the focusing direction F, and rotatably supported around the center of gravity axis K of the movable part, and the eight linkages are supported by the frame member 6. The relative positional relationship of the portions 5d is maintained.

For this reason, first, the tracking direction T is adjusted by a parallel plate spring arranged in a plane perpendicular to the focus direction F.
By simultaneously supporting the lens and supporting it in the focusing direction, the device can be made thinner, the support mechanism can be simplified, and the number of parts can be omitted, thereby reducing costs.

Further, by fixing the eight linking parts 5d by the frame member 6 and maintaining the relative positional relationship of the eight linking parts 5d, it is possible to prevent the parallel plate spring 5 from fluttering and to prevent the lens holder 2 from fluttering. When the objective lens 1 is driven in the focus direction F and the tracking direction T by matching the rotation center in the tracking direction T and the support position in the focus direction F with the substantially center of gravity position of the movable part, the lens holder 2 is moved in the tracking direction. Rotation around an axis parallel to T and tracking direction T and focus direction F
rotation about an axis perpendicular to the axis does not occur, and displacement frequency response characteristics in the focus direction F and tracking direction T do not deteriorate.

As described above, it is possible to realize an objective lens driving device that is thin and capable of reducing costs, and also provides stable displacement frequency response characteristics in the focus direction F and tracking direction T.

An objective lens driving device according to a second embodiment of the present invention will be explained below with reference to the drawings.

FIG. 4 is a perspective view showing the configuration of an objective lens drive device according to a second embodiment of the present invention, and FIG. 5 is a developed view of an integrated parallel plate spring of the objective lens drive device according to the second embodiment. Figure 6
FIG. 2 is a perspective view showing the assembly of an integral parallel plate spring of the objective lens driving device of the second embodiment.

In FIGS. 4, 5 and 6, F is a focus direction, T is a tracking direction, 21 is an objective lens, 22 is a lens holder that holds the objective lens 21, and 23 is a lens holder that holds the objective lens 21.
is a balance member, 24a and 24b are permanent magnets fixed to the lens holder, K is the objective lens 21, and the lens holder 2.
2. A center of gravity axis that passes through the approximate center of gravity of the movable part consisting of the balance member 23 and permanent magnets 24a and 24b and is approximately parallel to the optical axis of the objective lens 21; 25 is a pair of opposing parallel surfaces formed by bending one leaf spring; An integrated parallel plate consisting of a box-shaped frame part 25e having a torsion center part 25a and a tracking support part 25b, and a focusing support part 25c that supports a movable part movably in the optical axis direction via the box-shaped frame part 25e. 25d is a linking portion between the tracking support portion 25b and the focusing support portion 25c of the integrated parallel plate spring 25, and 27a and 27b are permanent magnets 24.
an opposing yoke, 28a, installed opposite to a, 24b;
28b is a focus coil that is wound around the opposing yokes 27a, 27b and drives the objective lens 21 in the focusing direction F by the permanent magnets 24a, 24b;
4b is a tracking coil that drives the objective lens 21 in the tracking direction T; 30 is an integrated parallel plate spring 2;
31 is a base/coupling yoke that fixes one end of 5 and fixes the opposing yokes 27a and 27b; 31 is a base/coupling yoke 2;
This is an auxiliary yoke fixed to 9.

Further, 25f is a bending line of the integrated parallel plate spring, and 26 is a bonded portion of the integrated parallel plate spring 25 bonded with a viscoelastic ultraviolet curing resin.

In the objective lens driving device constructed as described above, the assembly of the integrated parallel plate spring will first be explained.

The integrated parallel plate spring 25 is formed by bending one plate spring along a bending line 25f as shown in FIG. It is assembled by forming a frame portion 25e and then bonding an adhesive portion 26 using a viscoelastic ultraviolet curing resin as shown in FIG.

The operation of the objective lens driving device constructed as described above will be explained below.

First, the focus direction F of the objective lens 21
is driven by the electromagnetic action of focusing coils 28a, 28b wound around opposing yokes 27a, 27b and permanent magnets 24a, 24b attached to lens holder 22.
This is obtained by causing the lens holder 22 to move translationally in the focus direction F due to the bending, and the objective lens 21 to be driven in the focus direction F.

The objective lens 21 is driven in the tracking direction T by tracking coils 27a and 27b wound around the opposing yokes 26a and 26b and by the lens holder 22.
Due to electromagnetic interaction with permanent magnets 24a and 24b attached to is obtained by driving in the tracking direction T.

As described above, according to the second embodiment of the present invention, the torsion center portion 25a and the elliptical tracking support portions 25 are arranged radially around the torsion center portion 25a.
The movable part is held between the torsion center part 25a from the direction of the center of gravity axis K by the integrated parallel plate spring 25 having the shape b, and is supported so as to be movable in the focusing direction F, and is also rotatable around the center of gravity axis K of the movable part. The box-shaped frame portion 25e relatively maintains the positional relationship of the eight linking portions 5c.

The adhesive portion 26 of the integrated parallel plate spring 25 is bonded with a viscoelastic ultraviolet curing resin.

For this reason, first, by simultaneously supporting the tracking direction T and the focusing direction using an integrated parallel plate spring disposed on a plane perpendicular to the focusing direction F, the device can be made thinner and the support mechanism can be simplified. In addition, the number of parts can be omitted, and costs can be reduced.

Furthermore, a box-shaped frame portion 25e having a torsion center portion 25a and a tracking support portion 25b is formed on two opposing parallel surfaces by bending one leaf spring.
By maintaining the relative positional relationship of the two linking portions 25d, it is possible to prevent the integrated parallel plate spring 25 from fluttering, and to maintain the rotation center of the lens holder 22 in the tracking direction T and the support position in the focus direction F, as well as the movable portion. When driving the objective lens 21 in the focus direction F and the tracking direction T, the lens holder 22 rotates around an axis parallel to the tracking direction T and rotates in the tracking direction T and the focus direction F. Focus direction F without causing rotation around an axis perpendicular to
Also, the displacement frequency response characteristics in the tracking direction T are not deteriorated.

Furthermore, in order to maintain the relative positional relationship of the eight linking parts 25d, one leaf spring is bent to form a box-shaped structure having a torsion center part 25a and a tracking support part 25b on two opposing parallel surfaces. Since the frame part 25e is formed, the number of parts can be further omitted, and since the frame is formed by a plate spring, the weight of the frame can be reduced, and when driving the movable part in the focus direction F, the acceleration characteristics can be improved. can be improved.

Furthermore, the adhesive portion 26 of the integrated parallel leaf spring 25
is bonded with a viscoelastic ultraviolet curable resin, it is possible to reduce the resonance value of the resonance generated by the distortion of the integrated parallel plate spring 25 due to elongation of the tracking support part 25b, etc., and to move the movable part in the tracking direction T. Stable displacement frequency response characteristics can be obtained when driven at

As described above, it is possible to realize an objective lens driving device that is thin, enables cost reduction, and provides stable displacement frequency response characteristics in the focus direction F and tracking direction T.

[0041]

Effects of the Invention As described above, the present invention allows a movable part to move approximately from the center of gravity of the movable part using a parallel plate spring having a torsion center and an elliptical tracking support part arranged radially around the torsion center. The movable part is supported movably in the focusing direction by being pinched by the twisting center from an axial direction that is approximately parallel to the optical axis, and rotatable around an axis that passes through the center of gravity of the movable part and is approximately parallel to the optical axis. A means is provided for relatively maintaining the positional relationship of the plurality of linking parts of the focusing support part and the tracking support part of the parallel leaf spring.

For this reason, first, support in the tracking direction and support in the focusing direction are simultaneously provided by parallel leaf springs disposed on a plane perpendicular to the focusing direction, thereby making the device thinner, simplifying the supporting mechanism, and reducing the number of parts. This makes it possible to omit it, thereby realizing cost reduction.

Furthermore, by maintaining the relative positional relationship of the linking parts, it is possible to prevent the parallel plate springs from fluttering, and to keep the center of rotation of the lens holder in the tracking direction and the support position in the focusing direction, and the approximate position of the movable part. When driving the objective lens in the focus and tracking directions by matching the center of gravity, the lens holder can rotate around an axis parallel to the tracking direction and around an axis perpendicular to the tracking and focus directions. The displacement frequency response characteristics in the focusing direction and the tracking direction will not deteriorate.

Furthermore, in order to maintain the relative positional relationship of the linking parts, one leaf spring is bent to form a box-shaped frame part having a torsion center part and a tracking support part on two opposing parallel surfaces. By using an integrated parallel plate spring, it is possible to further reduce the number of parts, and since the frame is formed by plate springs, the weight of the frame can be reduced, and the acceleration characteristics can be improved when driving the movable part in the focus direction. can be improved.

Furthermore, by bonding the unbent ridges of the box-shaped frame portion of the integrated parallel plate spring with a viscoelastic material, resonance generated by distortion of the integrated parallel plate spring due to elongation of the tracking support portion, etc., can be suppressed. The resonance value can be reduced, and stable displacement frequency response characteristics can be obtained when the movable part is driven in the focusing direction and the tracking direction.

As described above, it is possible to realize an objective lens driving device that is thin, enables cost reduction, and provides stable displacement frequency response characteristics in the focusing direction and the tracking direction.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the configuration of an objective lens driving device in a first embodiment of the present invention.

FIG. 2 is an exploded perspective view showing the configuration of an objective lens driving device in a first embodiment of the present invention.

FIG. 3 is a plan view showing the operation of the objective lens driving device in the tracking direction in the first embodiment of the present invention.

FIG. 4 is a perspective view showing the configuration of an objective lens driving device in a second embodiment of the present invention.

FIG. 5 is a developed view of an integral parallel leaf spring of an objective lens driving device in a second embodiment of the present invention.

FIG. 6 is a perspective view showing the assembly of an integral parallel plate spring of an objective lens drive device in a second embodiment of the present invention.

FIG. 7 is a perspective view showing the configuration of a conventional objective lens driving device.

[Explanation of symbols]

F Focus direction T Tracking direction K Center of gravity axis 1 Objective lens 2 Lens holder 3 Balance members 4a, 4b Permanent magnet 5 Parallel leaf spring 5a Twisted center portion 5b of parallel leaf spring 5 Tracking support portion 5c of parallel leaf spring 5 Parallel leaf spring 5 Focusing support part 5d Connecting part 6 of parallel plate spring 5 Frame members 7a, 7b Opposing yokes 8a, 8b Focusing coils 9a, 9b Tracking coil 10 Base and connection yoke 11 Auxiliary yoke 21 Objective lens 22 Lens holder 23 Balance members 24a, 24b Permanent magnet 25 Integrated parallel plate spring 25a Torsion center portion 25b of integrated parallel plate spring 25
Tracking support portion 25c of integrated parallel plate spring 25
Focusing support portion 25d of integrated parallel plate spring 25
Linkage portion 25e of integrated parallel plate spring 25 Box-shaped frame portion 25f of integrated parallel plate spring 25 Bending line 26 of integrated parallel plate spring 25 Adhesive portions 27a, 27b of integrated parallel plate spring 25 Opposing yokes 28a, 28b Focusing coils 29a, 29b Tracking coil 30 Base/coupling yoke 31 Auxiliary yoke 101 Objective lens 102 Lens holder 103 Intermediate member 104 Fixing member 105 Parallel plate spring for tracking 106 Parallel plate spring for focusing 107 Focusing coils 108a, 108b Tracking coil 109a,
109b Driving magnet

Claims (5)

[Claims] 1. A movable part comprising an objective lens of a device for writing or reading optical information on a disc-shaped recording medium, a lens holder for holding the objective lens, and a balance member fixed to the lens holder. a torsion center portion that holds the movable portion in an axial direction that passes through the center of gravity and is substantially parallel to the optical axis of the objective lens; and a plurality of tracking support portions formed radially around the torsion center portion;
Furthermore, a parallel plate including two leaf springs arranged in parallel, each of which includes the torsion center portion and a focusing support portion that also serves as the plurality of tracking support portions and supports the movable portion movably in the optical axis direction. means for relatively maintaining the positional relationship between a spring, a plurality of linking parts of the focusing support part and the tracking support part of the parallel plate spring, and fixing one end of the focusing support part of the parallel plate spring. It is composed of a fixed member, a tracking drive means for moving the objective lens in a radial direction parallel to the disc-shaped recording medium, and a focusing drive means for moving the objective lens in the optical axis direction, An objective lens driving device, wherein the tracking support portion has one or more bent portions. 2. Means for relatively maintaining the positional relationship of a plurality of linking parts between a focusing support part and a tracking support part of a parallel leaf spring is a means for relatively maintaining a positional relationship between a plurality of linkage parts between the tracking support part and the focusing support part. 2. The objective lens driving device according to claim 1, further comprising means for fixing the portion by a frame member. 3. The means for relatively maintaining the positional relationship of the plurality of linking parts of the focusing support part and the tracking support part of the parallel leaf springs is provided by using one leaf spring instead of two parallel leaf springs. A box-shaped frame part that is bent to have a torsion center part and a tracking support part on two opposing parallel surfaces, and a focusing support part that supports a movable part so as to be movable in the optical axis direction via the box-shaped frame part. 2. The objective lens driving device according to claim 1, wherein the plurality of linking portions are fixed to each other by a part of a box-shaped frame portion. 4. The objective lens driving device according to claim 3, wherein a part of the unbent ridgeline of the box-shaped frame portion of the integrated parallel plate spring is bonded with a viscoelastic material. 5. The objective lens driving device according to claim 4, wherein the viscoelastic material is an ultraviolet curing resin or a silicone adhesive.