KR100366837B1 - A biaxial actuator - Google Patents

Abstract

Provided is a biaxial actuator that firmly supports the base plate, has a simple structure, simplifies the assembly process, is easy to adjust, reduces the cost, and can perform optical axis adjustment of the objective lens.

A lens holder 12 to which the objective lens 11 is fixed, and a fixing member 15 for supporting the lens holder 12 in the biaxial direction of the focusing direction F and the tracking direction T via the suspension wire 13. ), And a driving unit made of a focusing coil 17 for driving the lens holder 12, a tracking coil 18, a yoke 14c, and magnets 19a and 19b fixed to the yoke 14c, at least a base plate ( At the same time, the one end along the tracking direction T on the objective lens 11 side of the base plate 14 is cantilevered in the pickup chassis 22 by screws 21 and 21. And both sides of the other end are movable supported by screws 23a and 23b.

Description

Biaxial Actuators {A BIAXIAL ACTUATOR}

The present invention relates to, for example, a biaxial actuator for optical pickup used for recording or reproducing a signal on an optical disc.

Background Art Conventionally, optical pickups have been used to record or reproduce information signals on optical discs such as CDs (compact discs) and DVDs (digital video discs or digital buffer tiles). The optical pickup has a light emitting element for emitting a laser beam, a light receiving element for receiving a laser beam, an optical system for inducing a laser beam, and an objective lens for condensing a laser beam.

The laser beam emitted from the light emitting element is guided to the objective lens by the optical system and condensed by the objective lens. The objective lens is driven in the optical axis direction (focusing direction) of the objective lens so that this condensing beam is always focused on the information recording surface of the optical disk with respect to the surface vibration of the optical disk, and the radial direction (tracking) of the optical disk so as to follow the information recording track. Direction), the return light, which is the reflected light of the laser beam changed in accordance with the information signal from the information recording surface of the optical disk, is received by the optical element again through the objective lens and the optical system, and converted into an output signal to convert the information signal. Playback or recording of the information signal is performed.

As the above-described driving device of the objective lens, an actuator for driving in two axes of the electronic driving focusing direction and the tracking direction, i.e., a biaxial actuator, is used. The biaxial actuator includes a lens holder to which an objective lens is attached, a fixing member serving as a fixing portion for supporting a lens holder serving as a movable portion, and a driving portion for generating driving force.

Hereinafter, an example of the conventional biaxial actuator is demonstrated with the top view, partial cross section side view of the biaxial actuator 100 shown to FIG. 5, FIG. 6, and FIG. 7, respectively, and the partial cross section front view seen from the S2 direction of FIG. 5 and 6, one end of each of the two suspension wires 103 and 103 is fixed to the arm portions 102a and 102a on both sides of the lens holder 102 to which the objective lens 101 is fixed. It is. In addition, each other end of the suspension wire 103 is supported in a cantilever shape by a fixing member 105 fixed to the base plate 104, whereby the lens holder 102 has a tracking direction T and a focusing direction F. As shown in FIG. It is supported to be able to move in biaxial direction.

Further, the focusing coil 106 and two tracking coils 107 and 107 adjacent to the focusing coil 106 and the objective lens 101 side are fixed to the lens holder 102. In addition, in the base plate 104, as shown in Fig. 6, a yoke 108 having an upper portion opened in a substantially U-shape has a hole 102b in which the bent piece 108a is formed in the lens holder 102. Is inserted into the hollow core hole 106a of the focusing coil 106 so that the bending piece 108b fixed to the bending piece 108a and the magnet 109 is opposed to the bending piece 108a. 108b) The tracking coils 107, 107 and one side of the focusing coil 106 are attached and fixed to each other. 6, the top yoke 115 is fixed to the yoke 108 so as to close the opening of the yoke 108 (omitted in FIG. 5).

As a result, when the tracking coils 107 and 107 are energized, the magnetic field generated in this coil interacts with the magnetic field generated by the magnet 109 fixed to the yoke 108 and the bent piece 108b. The lens holder 102 having the coil fixed thereto is driven in the T direction in FIG. Similarly, when energizing the focusing coil 106, the lens holder 102 is driven in the F direction in FIG. Therefore, the objective lens 101 fixed to the lens holder 102 is driven in the tracking direction T and the focusing direction F. FIG.

On the other hand, in the base plate 104, a spherical protrusion 104a is formed on the pickup chassis 110 side, and the protrusion 104a is formed on a spherical recess 110a formed in the pickup chassis 110. It is made to contact. In addition, instead of the spherical protrusion 104a, as shown in FIG. 8, a round awl-shaped protrusion 114 may be formed in the base plate 104 in some cases.

Moreover, the bent part 104b is bent and formed in the one side part of the one end part along the T direction of the objective lens 101 side of the base plate 104, The press surface 104c which is one surface is the pickup chassis 110 ) Is elastically applied in the A direction shown in FIG. 6 by the other end of the leaf spring 112 whose one end is fixed by the screw 111.

Moreover, support parts 104d and 104e are formed in the both sides of the other end part on the opposite side to the objective lens 101 of the base plate 104, and as shown in FIG. 6, from the lower side of the pickup chassis 110 upwards. The other end of the base plate 104 is supported by fitting the leading ends of the inserted screw members 113a and 113b into the screw holes 104f and 104g formed in the support portions 104d and 104e, respectively.

With such a configuration, the base plate 104 is tangential to the optical disc (not shown) shown in FIGS. 6 and 7, that is, in the tangential (TAN) direction and in the same radial direction, that is, the radial (RAD) direction. By adjusting the rotation, the optical axis B of the objective lens 101 is substantially perpendicular to the optical disk surface, and the optical axis adjustment is performed so that optimal recording or reproduction can be performed. Specifically, the TAN direction can be adjusted by rotating the screw members 113a and 113b shown in FIG. 6 and moving the support portions 104d and 104e by the same distance in either direction in the C direction in the figure. .

In addition, in FIG. 7, the RAD direction can be adjusted by rotating only the screw member 113b, and moving the support part 104e to the D direction in the figure, without rotating the screw member 113a. On the contrary, the RAD direction can be adjusted by rotating only the screw member 113a or rotating the screw members 113a and 113b in opposite directions without rotating the screw member 113b.

As described above, the optical axis adjustment of the objective lens 101 is performed by the rotation adjustment of the base plate 104 with respect to the pickup chassis 110, and the attachment of the biaxial actuator 100 to the pickup chassis 110 is completed.

However, in the conventional biaxial actuator 100 described above, the leaf spring 112 for pressing the base member 104 and the spherical or round awl-shaped protrusions 104a and 114 are required and the cost increases. In addition, the structure is complicated.

On the other hand, since the pressing surface 104c of the base member 104 is elastically applied by the leaf spring 112, the biaxial actuator so that the condensing beam emitted from the objective lens 101 can follow the information recording surface of the optical disk. When servo control 100, the elastic component of the leaf spring 112 is disturbed and unnecessary resonance occurs, so as to follow the surface vibration of the information recording surface and the undulation of the information recording track or the surface of the optical disk, Even if there are scratches or the like, the frequency characteristics of the biaxial actuator for tracking the information recording track may deteriorate, making it impossible to read the information signal.

In order to prevent this, there has been a method of fixing the leaf spring 112 on the pressing surface 104c of the base plate 104 with an adhesive or the like, but since the portion of the leaf spring 112 is fixed, the base plate 104 is fixed. It cannot be fixed firmly with respect to the pickup chassis 110, the improvement of the frequency characteristic is insufficient, and the addition of an assembly process for adhesion has been required.

Moreover, although the method of fixing the base plate 104 firmly with respect to the pickup chassis 110 can be considered by adhesively fixing the whole leaf spring 112 including the said pressing surface 104c, the leaf spring 112 can be considered. It is not a practical method, such as a jig for bonding so as to enclose it, and a long working time is required.

In addition, as shown in Fig. 6, when the screw members 113a and 113b are screwed into the screw holes 104f and 104g formed in the support portions 104d and 104e of the base plate 104, the support portions 104d and 104e are formed. As the initial position of the adjustment direction C, the base member 104 and the pick-up chassis 110 are usually set to be substantially parallel, but the base member 104 and the pick-up chassis 110 are generally parallel. This is difficult because the member 104 is close to the bottom of the pickup chassis 110. Therefore, unless the detection means for knowing the initial position of the adjustment direction C is provided, the optical axis adjustment is difficult because the range is ambiguous. Forming the detection means is not practical because it leads to increased costs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a biaxial actuator capable of firmly supporting a base plate, having a simple structure, simplifying an assembling process, making it easy to adjust, reducing costs, and adjusting an optical axis of an objective lens. .

1 is a perspective view of a biaxial actuator that is an embodiment of the present invention.

2 is a plan view of a biaxial actuator that is an embodiment of the present invention.

3 is a partial cross-sectional side view of a biaxial actuator according to an embodiment of the present invention.

It is a front view seen from the S1 direction of FIG. 2 with respect to the biaxial actuator which is embodiment of this invention.

5 is a plan view of a conventional biaxial actuator.

6 is a partial cross-sectional side view of a conventional biaxial actuator.

FIG. 7 relates to a conventional biaxial actuator, and is a partial sectional front view seen from the direction S2 of FIG. 5.

8 is a partial cross-sectional side view of another conventional biaxial actuator.

Explanation of symbols on the main parts of the drawings

10: biaxial actuator 11: objective lens

12: lens holder 13: suspension wire

14: base plate 14c: yoke

15: fixing member 16: substrate

21, 23a, 23b: screw 22: pickup chassis

As a first solution for solving the above problems, there is provided a lens holder having an objective lens fixed thereto, a fixing member for supporting the lens holder in a biaxial direction in a focusing direction and a tracking direction, a focusing coil for driving the lens holder, While at least a driving unit comprising a tracking coil and a yoke and a magnet fixed to the yoke is arranged at least in the base member, one end along the tracking direction of the base member is fixedly supported in a cantilever shape, and the other end is provided. It is characterized in that the movable support in the focusing direction.

Further, as a second solution, one end of the base member is disposed on the mounting surface of the chassis and is fixed to the mounting surface by the first screw member, and both sides of the other end are respectively supported by the second screw member. At the same time, the objective lens is arranged on one end side, and the fixing member is arranged on the other end side.

Further, as a third solution means, the arrangement surface is characterized in that the inclined surface.

In addition, as a fourth solution, the base member is a steel sheet, and the yoke is integrally formed by bending a part of the base member.

Embodiment of the Invention

The biaxial actuator 10 which is embodiment of this invention is demonstrated below using the perspective view, top view, partial cross section side view, and the front view which looked at S1 direction of FIG. 2, respectively, shown in FIG. 1, FIG. 2, FIG. 3, FIG. do.

1 to 3, one end of the suspension wires 13 and 13 is provided on the support portions 12a and 12a formed on both sides in the T direction of the lens holder 12 to which the objective lens 11 is fixed. Are fixed respectively. In addition, the other ends of the respective suspension wires 13 and 13 are soldered to the substrate 16 attached to the side opposite to the objective lens 11 side of the fixing member 15 attached to the base plate 14 serving as the base member. The lens holder 12 is supported so as to be movable in the biaxial direction of the tracking direction T and the focusing direction F with respect to the fixing member 15. The base plate 14 is formed of a steel sheet.

The lens holder 12 is formed by winding the focusing coil 17 and the winding coil in the direction orthogonal to the winding direction of the focusing coil 17 and adjoining the objective lens 11 side of the focusing coil 17. Tracking coils 18 and 18 are fixed. Moreover, in the base board 14, as shown in FIG. 3, the bending piece 14a and 14b which bent the part of the base board 14 are formed, and the yoke 14c which the upper part is opened in U shape is opened. It consists. In addition, magnets 19a and 19b are fixed to the bent pieces 14a and 14b so as to face each other with different poles. Moreover, the top yoke 20 is fixed so that the open upper part of the yoke 14c may be closed.

The bending piece 14a to which the magnet 19a is fixed is inserted into the hole 12b formed in the lens holder 12, and the bending piece 14b to which the magnet 19b is fixed is the air core of the focusing coil 17. By being inserted into the hole, the yoke 14c is arranged so that the magnets 19a and 19b sandwich the tracking coils 18 and 18 and one side of the focusing coil 17.

As a result, when the tracking coils 18 and 18 are energized, the magnetic field generated in the coil is generated by the magnets 19a and 19b fixed to the yoke 14c and the bent pieces 14a and 14b, respectively. By interacting, the lens holder 12 fixing the respective coils is driven in the T direction in FIG. Similarly, when energizing the focusing coil 17, the lens holder 12 is driven in the F direction in FIG. Therefore, the objective lens 11 fixed to the lens holder 12 is driven in the tracking direction T and the focusing direction F. As shown in FIG.

With the above configuration, the laser beam emitted from the light emitting element of the optical pickup (not shown) is imaged on the information recording surface of the optical disc via the objective lens 11. The returned light from the information recording surface of the optical disc passes through the objective lens 11 again and enters the photodetector of the optical pickup, whereby the information recorded on the information recording surface is read. At that time, the energization of the focusing coil 17 and the tracking coils 18 and 18 fixed to the lens holder 12 is properly controlled, so that the focusing and tracking operations of the objective lens 11 are performed.

On the other hand, as shown in FIG. 2, attachment portions 14d and 14d are formed on both sides of one end portion along the T direction on the objective lens 11 side of the base plate 14. And the attachment part 14d, 14d is fixed to the inclined surface 22a (refer FIG. 3) which is an arrangement surface of the pickup chassis 22 which is a chassis by the screws 21 and 21 which are 1st screw members, and a base The plate 14 is firmly supported in the cantilever shape with respect to the pickup chassis 22.

Moreover, the screw holes 14g and 14h are formed in the support parts 14e and 14f formed in the both sides of the other end part of the base board 14, respectively, and as shown in FIG. The other end of the base plate 14 is supported by fitting the distal end portions of the screws 23a and 23b, which are second screw members inserted through from above, into the screw holes 14g and 14h, respectively.

With this configuration, the base plate 14 is rotated in the tangential direction of the optical disc 30 shown in Figs. 3 and 4, respectively, in the tangential (TAN) direction, and in the same radial direction, that is, the radial (RAD) direction. By this adjustment, the optical axis B of the objective lens 11 becomes substantially perpendicular to the plane of the optical disc 30, and the optical axis adjustment is performed so that recording or reproduction by the optimal condensing beam can be performed.

Next, the specific method of optical axis adjustment is demonstrated.

First, as shown in FIG. 3, in the base plate 14 inclined in the direction in which the support portions 14e and 14f are separated from the pickup chassis 22 by an angle θ with respect to the horizontal line H, the screw members 23a and 23b. And the support portions 14e and 14f to elastically deform the root portions 14i and 14i (see FIG. 2) of the base member 14 at the end portion in the direction of the fixing member 15 of the inclined surface 22a. Is moved by the same distance from the position P to Q by the same distance, so that the rotation angle of approximately 2θ of the base plate 14 can be secured. The base plate 14 may not be elastically deformable, or may be plastically deformable.

At this time, since the fixing member 15 is disposed close to the supporting portions 14e and 14f of the base plate 14, the bottom surface 15a of the fixing member 15 is also almost in accordance with the rotation of the base plate 14. Rotate to be at the same angle. Therefore, the optical axis B of the objective lens 11 fixed to the lens holder 12 connected through the fixing member 15 and the suspension wire 13 is similarly moved from position P to Q of the base plate 14. In accordance with the rotation of the angle 2θ , it rotates from P 'to Q' such that it is approximately the same angle θ '. In this manner, the adjustment range in the TAN direction can be secured. In addition, the angle θ 'may be determined in advance by taking into consideration the initial angle unevenness of the optical axis B due to the dimensional tolerance of the member constituting the biaxial actuator 10 or the like. In addition, although the adjustment range of the base member 14 was 2 ( theta) , it is not limited to this, You may change as needed. In addition, although the said angle 2 ( theta) was drawn in extremely large in order to make it easy to understand in FIG. 3, since it is actually a minute angle, in the said adjustment range, the tracking coils 18, 18, the focusing coil 17, etc. are a magnet 19a, There is no contact with 19b).

Then, for example, while reproducing the optical disc 30 by optical pickup, the screws 23a and 23b are rotated, the support portions 14e and 14f are gradually moved by the same distance in the same direction from the position P to Q, and the reproduction is performed. By adjusting the signal so that it is best, the optical axis of the objective lens 11 in the TAN direction can be adjusted.

Next, as shown in FIG. 4, by rotating only the screw member 23b without moving the screw 23a and moving the support part 14f in the M direction in the figure, or without rotating the screw 23b, By rotating only the screw 23a and moving the support part 14e in the N direction in the figure, the optical axis adjustment in the RAD direction can be performed.

As described above, the optical axis adjustment of the objective lens 11 is performed by adjusting the rotation of the base plate 14 with respect to the pickup chassis 22, and the attachment fixing of the biaxial actuator 10 to the pickup chassis 22 is completed. do.

As described above, according to the biaxial actuator 10 of the present embodiment, since the base plate 14 is fixedly supported by the pickup chassis 22 in a cantilever shape, the base plate 14 is mounted on the pickup chassis 22. It can be firmly supported, and therefore, the disturbance which is an elastic component can be greatly reduced, and even if there is dirt, scratches, or the like on the surface of the optical disk, or to track the surface vibration of the optical disk and the undulation of the information recording track, The frequency characteristic of the biaxial actuator for tracking is improved, and the information signal of the optical disc can be read without errors. In addition, since the base plate 14 is fixedly supported in a cantilever shape, it is not necessary to form spherical or round awl-shaped protrusions on the leaf spring and the base member, thereby simplifying the structure. In addition, the cost can be reduced accordingly.

Moreover, since only the base plate 14 is screwed to the pickup chassis 22 by the screws 21 and 21, the bonding process is unnecessary and the assembly process is simplified.

In addition, as shown in FIG. 3, when adjusting the optical axis B of the objective lens 11, only the support part 14e or 14f of the base board 14 is gradually moved to one direction from the position P to Q. Since the position P, which is the initial position, is determined at the time when the attachment portions 14d and 14d of the base plate 14 are fixed by the screws 21 and 21 to the inclined surface 22a of the pickup chassis 22, the optical axis The effect is easy to adjust.

In addition, since the base plate 14 is made of steel sheet, the material is inexpensive, and since the yoke 14c is integrally formed by the bent pieces 14a, 14b in which a part of the base plate 14 is bent, the base is It is not necessary to attach and fix the yoke separately to the plate, and the bending pieces 14a and 14b can be processed simultaneously when the base plate 14 is processed, thereby reducing the cost.

In addition, in this embodiment, attachment parts 14d and 14d for attaching the base plate 14 to the inclined surface 22a of the pickup chassis 22 are attached to the base plate 14 as shown in FIG. 2. Since it can be formed on both sides of the yoke 14c integrally formed, the base of this embodiment compared with the length L2 of the base board 110 in the conventional biaxial actuator 100 (refer FIG. 5). Since the length L1 of the plate 14 can be shortened, if the same plate thickness and rigidity are substantially the same, the amount of warpage at the end can be reduced when a load is applied to the end of the base plate. It can reduce the frequency and improve the frequency characteristic of biaxial actuator.

As described above, the biaxial actuator according to the present invention includes a lens holder to which an objective lens is fixed, a fixing member for supporting the lens holder in a biaxial direction in a focusing direction and a tracking direction, and a focusing coil for driving the lens holder. And a driving unit comprising at least a tracking coil, a yoke and a magnet fixed to the yoke, is arranged at least on the base member, and one end of the base member along the tracking direction is fixedly supported in a cantilever shape, and Since the end is movable in the focusing direction, the interposition such as the leaf spring is eliminated, so that the base member can be firmly supported, and the leaf spring for applying the force to the base member and the spherical or round awl formed on the base member. The structure can be simplified because there is no need to form protrusions of Use can be reduced.

One end of the base member is disposed on the mounting surface of the chassis and is fixed to the mounting surface by the first screw member, and both sides of the other end are respectively supported by the second screw member, and the objective lens is one side. Since the fixing member is arranged on the other end side, the fixing member is arranged on the other end side, so that the bonding step is unnecessary and the assembly step can be simplified.

In addition, since the mounting surface is an inclined surface, when adjusting the optical axis of the objective lens, only the two sides of the other end of the base member are gradually moved in one direction, and the initial position of the other end of the base member is Since it is determined when the end of one end of the base member is fixed to the placement surface, there is an effect that the optical axis adjustment is easy.

In addition, since the base member is a steel plate and the yoke is integrally formed by bending a part of the base member, the material is inexpensive and there is no need to attach and fix the yoke separately to the base member. Since the yoke can be processed simultaneously during processing, the cost can be reduced.

Claims (4)

A lens holder to which an objective lens is fixed, a fixing member for movably supporting the lens holder in a biaxial direction of a focusing direction and a tracking direction, a focusing coil driving the lens holder, a tracking coil, a yoke, and a magnet fixed to the yoke At least one driving portion formed at least on the base member is arranged, and one end portion of the base member in the tracking direction is disposed on the mounting surface of the chassis and fixedly supported in the cantilever shape by the first screw member on the mounting surface. And both sides of the other end are respectively supported in the focusing direction by the second screw member, the objective lens is arranged on one end side, and the fixing member is arranged on the other end side. A biaxial actuator characterized by the above-mentioned. delete 2. The biaxial actuator according to claim 1, wherein the placement surface is an inclined surface. The biaxial actuator according to claim 1 or 3, wherein the base member is a steel sheet and the yoke is integrally formed by bending a part of the base member.