JP2001143291A - Optical head actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the function for correcting inclination of optical axis of an objective lens of an optical head and also to simplify the control of the inclination when an actuator is driven. SOLUTION: A carriage base 3 is supported by a knife-edge part 2a of a carriage 2 so that the base 3 can freely rock around an axis Y set in the tracking direction, and a knife-edge part 4a of an actuator base 4 is engaged with the base 3 so that the base 4 can freely rock around an axis X set in the track tangent direction. The screws 12a and 12b are located between the carriage 2 and the base 3 and holding the axis Y between them, and the screws 13a and 13b are located between both bases 3 and 4 and holding the axis X between them. In such a constitution, the rocking angles can be individually controlled around each axis and the inclination of an optical axis can be corrected with high stability and high accuracy without causing any crosstalk.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical head actuator suitable for correcting a tilt of an optical axis of an objective lens actuator used in an optical disk device or the like.

[0002]

2. Description of the Related Art Conventionally, when an objective lens actuator used for an optical disk device or the like is mounted on a drive device, an actuator body 8 having an objective lens 9 is fixed to an actuator base 4 as shown in FIG. The actuator base 4 in which the main body 5 is integrated is screwed to the carriage 2 at three points indicated by arrows D, EF in the figure (three places in the figure). In addition,
The carriage 2 moves the actuator body 5 in a seek direction (arrow S in the figure) intersecting the track direction of the optical disk (not shown).

By the way, the optical axis C of the objective lens 9 constituting the actuator may be inclined with respect to the disk recording surface due to various mechanical mounting errors and the inclination of the disk recording surface when the disk rotates. Since this inclination has an optically adverse effect, it is necessary to correct it. For example, when the point indicated by the arrow D in the drawing is used as a reference, the actuator base 4 can be inclined by tightening or loosening each screw corresponding to the point indicated by the arrow E or the arrow F. Thus, the optical axis C can be corrected with respect to the optical disk recording surface. After the correction is completed, the state is completely fixed by, for example, an adhesive or the like in order to maintain the state.

Further, when the objective lens 9 is driven in the focusing direction or the tracking direction, usually, various unnecessary moments are generated due to the above driving force, so that the optical axis C is tilted. As described above, the inclination of the optical axis C has an optically serious adverse effect as described above. Therefore, in the design of the actuator, efforts are made to reduce the generation of such unnecessary moment. However, with the recent increase in the density and capacity of optical discs, stable design of the optical axis cannot be maintained with such a design effort alone, and the yield in mass production may be reduced.

Therefore, when the movable member 8 for holding the objective lens 9 is driven when the tilt of the track of the optical disk is inclined in the tangential direction, and when the tilt control is not performed, as shown in an imaginary line in FIG. Tilt and the optical axis C tilts. A control method for generating a driving force for correcting the tilt (for example, controlling a focusing coil) has been proposed, whereby the tilt can be corrected as shown by a solid line in FIG. The same applies to the radial direction of the optical disk.

[0006]

The tilting direction of the optical axis of the objective lens in the optical head actuator can be omnidirectional, so that it is necessary to correct the optical axis tilted in various directions. In this case, the conventional method described above has a problem that, because of the support at three points, the tightening or loosening adjustment of the screws interferes with each other, and it is difficult to perform high-precision adjustment.

Further, in the control method for generating the correction driving force, since the driving control of the movable member of the actuator is used in combination with the driving control of the focusing and tracking, the driving control and the correction control interfere with each other. In addition, the amount of displacement (the amount of inclination) of the movable member must be detected, so that there is a problem that a detection mechanism is complicated, such as mounting a detector on the movable member.

[0008]

In order to solve the above problems, the function of correcting the tilt of the optical axis of the objective lens constituting the actuator of the optical head is improved, and the control of the tilt when the actuator is driven is simplified. To do
In the present invention, a movable member that holds an objective lens and includes a focusing coil and a tracking coil, and an actuator that displaces the movable member in the focusing direction and the tracking direction and supports the movable member at a neutral position via an elastic support member An actuator for an optical head having a base and a carriage for transporting the actuator base, wherein the carriage has a first
A swinging member that is swingably supported via the swinging support means, and wherein the swing member is provided between the actuator base and the swinging member around an axis intersecting an axis of the first swinging support means. The second that supports the actuator base swingably
And a first swing angle adjusting means for adjusting a swing angle of the swing member with respect to the carriage, and a swing angle of the actuator base with respect to the swing member. And a second swing angle adjusting means.

According to this structure, the swing member is swingably supported by the carriage, the actuator base is swingable with respect to the swing member, and the axes of the swing support means are aligned with each other. Since they intersect with each other, the swing angle of the swing member with respect to the carriage and the swing angle of the actuator base with respect to the swing member can be independently adjusted.

Further, when the swing angle adjusting means has an electric drive means, each swing angle can be automatically adjusted.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to specific examples shown in the accompanying drawings.

FIG. 1 is a perspective view showing an entire optical head actuator to which the present invention is applied. This optical head actuator is used for optically reading or writing data recorded on an optical disk (not shown). Used. FIG. 2 is an exploded perspective view of the optical head actuator of FIG.

As shown in FIGS. 1 and 2, a carriage 2 is supported by two parallel guide shafts 1,
The carriage 2 is movable in a seek direction (arrow S in the drawing), which is the axial direction of the guide shaft 1. The seek direction is a direction orthogonal to a tangent to a track of an optical disc (not shown).

The carriage 2 supports a plate-like carriage base 3 as a swing member, and a plate-like actuator base 4 is provided between the carriage 2 and the carriage base 3.
Are provided, but the actuator base 4 is supported by the carriage base 3. The actuator main body 5 is supported by the actuator base 4.

A fixed block 6 is fixed on the upper surface of the actuator base 4 by screwing.
The movable member 8 is supported by two wire springs 7 on the left and right sides as elastic support members. The wire spring 7 extends from the fixed block 6 along the upper surface of the actuator base 4,
The books are provided in parallel.

The movable member 8 is provided with an objective lens 9, a focusing coil 10a and a tracking coil 10b, and the actuator base 4 is provided with magnets 11 corresponding to the coils 10a and 10b. By appropriately passing a current through each of the coils 10a and 10b, the operating member 8, that is, the objective lens 9 is moved in the focusing direction orthogonal to the surface of the optical disk (arrow Z in FIG. 1).
And a tracking direction (direction indicated by arrow X in FIG. 1) orthogonal to the tangent line of the track of the optical disk. The optical axis C of the objective lens 9 is directed in the focusing direction.

The carriage base 3 has a V-shaped groove formed on a knife edge portion 2a disposed on the upper surface of the carriage 2 at a predetermined interval on a line perpendicular to the tracking direction (the direction indicated by arrow Y in FIG. 1). Are supported. The actuator base 4 has a knife edge portion 4a disposed on the upper surface thereof on the line in the tracking direction in the same manner as described above, and is engaged with a corresponding V-shaped groove of the carriage base 3.

In the illustrated example, the knife edge portion 2a
Are located on the Y axis in the direction of the arrow Y passing through the center of the objective lens 9, and the fulcrums of the knife edge portion 4 a are located on the X axis in the direction of the arrow X passing through the center of the objective lens 9. ing. Thus, the carriage base 3 can swing about the Y axis, and the actuator base 4 can swing about the X axis.

Further, since the actuator base 4 comes into contact with the carriage base 3 via the knife edge portion 4a around the Y axis, the carriage base 3 and the actuator base 4 are integrally formed around the Y axis. Rocks.
The carriage base 3 comes into contact with the knife edge 2a (carriage 2) around the X axis.
Only the actuator base 4 swings around the axis. Therefore, the movable member 8 (the objective lens 9)
It is swingable independently around each axis.

As shown in FIGS. 3 and 4, two screws inserted into the carriage 2 and penetrating the actuator base 4 are located at two positions on the carriage base 3 with the Y axis therebetween. 12a and 12b are screwed, and two screws 13a and 13b inserted into the carriage base 3 are screwed into two positions of the actuator base 4 with the X axis interposed therebetween. Note that corresponding portions of the carriage 2 are respectively recessed so that the screws 12a, 12b, 13a, and 13b can be turned from below the carriage 2 with a tool or the like.

As shown in FIG. 3 (a) as viewed from the arrow III line in FIG. 1, one of the two screws 12a and 12b is Y in the carriage base 3 as shown by the arrow A in the figure. It is for adjusting the swing angle around the axis,
The other screw 12b is for fixing the swing angle of the carriage base 3 adjusted by the one screw 12a. For this purpose, a pressurizing spring 14 composed of a coil spring is interposed between the head of the screw 12b and the carriage 2. Thus, the first swing angle adjusting means is configured.

As shown in FIG. 4 as viewed from the arrow IV in FIG. 1, one of the two screws 13a and 13b is connected to the actuator base 4 by an X-axis indicated by an arrow B in the figure. The other screw 13b is for adjusting the swing angle of the actuator base 4 adjusted by the one screw 13a. A pressurizing spring 15 is also interposed between the head of the screw 13b and the actuator base 4. In this manner, the second swing angle adjusting means is configured.

In assembling the optical head actuator, first, a fixed block 6 is fixed to the actuator base 4 to integrate the movable member 8 with the actuator base 4, and the knife edge 4a of the actuator base 4 is moved to the carriage. The actuator base 4 is engaged with the corresponding V-shaped groove of the base 3 and the actuator base 4 is temporarily fixed to the carriage base 3 by the screws 13a and 13b.
Next, the knife edge 2a of the carriage 2 is engaged with the V-shaped groove of the carriage base 3, and the screws 13a
13b, the carriage base 3 is temporarily fixed to the carriage 2.

If the optical axis C of the objective lens 9 is inclined around the X axis, the screw 13a is tightened or loosened to move the actuator base 4 in the forward / reverse rotation direction around the X axis. Lean towards you. According to the amount of rotation of the screw 13a, the actuator base 4 is tilted as exaggeratedly shown in FIG. 5 when the screw 13a is tightened, and the tilt of the optical axis C in the tangential direction of the optical disk track is corrected.

When the optical axis C is tilted around the Y axis, the carriage 12 is tilted in the forward and reverse directions around the Y axis by tightening or loosening the screw 12a. As a result, similarly to the above, the carriage base 3 is tilted as exaggeratedly shown in FIG. 3B, and the tilt of the optical axis C in the radial direction of the optical disk is corrected.

In any case, the inclination of the corresponding carriage base 3 and actuator base 4 is corrected by the above-described operation of the pressurizing springs 14 and 15 provided on the other screws 12b and 13b. Is held. In this way, the tilt adjustment can be completed. As shown in the illustrated example, since the inclination correction of the optical axis C in the tangential direction (around the X axis) of the track of the optical disk and the radial direction (around the Y axis) of the optical disk can be performed independently, the crosstalk is reduced. Does not occur, and stable and accurate tilt correction can be performed.

Further, according to the present invention, as shown in FIG. 6, between the head of one of the screws 12a and the corresponding surface of the carriage 2 (the bottom surface of the concave portion), a piezoelectric device as an electric driving means is provided. It is preferable to provide so as to sandwich the element 16. Similarly,
As shown in FIG. 7, a piezoelectric element 17 is provided between the head of the screw 13a and the actuator base 4.

Since the tilt amount of the actuator base 4 is hardly affected by other factors, a simple correlation is established between the tilt control signal and the tilt amount. Therefore, a voltage is applied to each of the piezoelectric elements 16 and 17 to apply a voltage to each of the piezoelectric elements 16 and 17.
The actuator base 4 can be tilted in the same manner as in the above-described example by expanding and contracting, and by performing such tilt control, the optical axis tilt control during driving of the actuator can be performed. By doing this,
It is possible to electrically correct automatically without manual correction as in the above-described example, and it is not necessary to detect the amount of tilt of the actuator itself (actuator base 4). The tilt correction control circuit can be configured with a simple control system.

In the illustrated example, a piezoelectric element is used. However, the present invention is not limited to the piezoelectric element, and any electric driving means may be used. For example, an electromagnetic displacement means such as a magnetostrictive element or a moving coil may be used. it can. Further, the invention is not limited to the combination of these and screws, and a piezoelectric element or the like may be used alone.

In the illustrated example, each swing axis is set so as to pass through the center of the objective lens so that the inclination of the optical axis of the objective lens can be corrected directly and easily. Each swing axis does not have to pass through the center of the objective lens. In this case, for example, the inclination of the optical axis with respect to each swing angle can be calculated and obtained on the control device side. Further, the swing axes do not need to be orthogonal to each other and do not need to intersect on each other, and the inclination of the optical axis can be calculated and obtained in the same manner as described above.

[0031]

As described above, according to the present invention, each swing angle can be adjusted by independently swinging the swing member and the actuator base around each axis of each swing support means crossing each other. The tilt of the optical axis,
Crosstalk does not occur, and the correction can be performed stably and accurately. In addition, since the tilt amount due to the above structure is hardly affected by other factors, a simple correlation is established between the tilt control signal and the tilt amount, so that each swing angle is adjusted by the electric driving means, Since it is not necessary to detect the tilt amount of the actuator itself and a simple control system can be configured, the optical axis tilt control at the time of driving the actuator can be automatically performed.

[Brief description of the drawings]

FIG. 1 is an overall perspective view of an optical head actuator according to the present invention.

FIG. 2 is an exploded perspective view of the optical head actuator of FIG. 1;

3A is a fragmentary end view showing a neutral position body of the actuator base as viewed from the arrow III line in FIG. 1, and FIG. 3B is a state in which the actuator base optical disc is inclined in the radial direction. FIG.

FIG. 4 is a fragmentary end view showing the neutral position body of the actuator base as viewed from the arrow IV line in FIG. 1;

FIG. 5 is a view corresponding to FIG. 4, showing a state in which the actuator-based optical disc is inclined in a track tangential direction of a track.

FIG. 6 is a diagram corresponding to FIG. 3A showing an example using a piezoelectric element.

FIG. 7 is a view corresponding to FIG. 4, showing an example using a piezoelectric element.

FIG. 8 is an exploded perspective view of a conventional optical head actuator.

FIG. 9 is a side view of an essential part for explaining a conventional optical axis tilt correction control method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Guide shaft 2 Carriage 3 Carriage base, 2a Knife edge part 4 Actuator base 5 Actuator main body, 4a Knife edge part 6 Fixed block 7 Wire spring 8 Movable member 9 Objective lens 10a Focusing coil 10b Tracking coil 11 Magnet 12a, 12b Screw 13a・ 13b screw 14.15 pressurized spring 16 piezoelectric element

Claims (2)

[Claims] A movable member for holding an objective lens and having a focusing coil and a tracking coil;
An actuator for an optical head, comprising: an actuator base that displaces the movable member in a focusing direction and a tracking direction and supports the neutral position via a resilient support member at a neutral position; and a carriage for transporting the actuator base. A swing member is provided on the carriage so as to be swingable via first swing support means, and intersects the axis of the first swing support means between the actuator base and the swing member. A second swing support means for swingably supporting the actuator base about an axis, and a first swing angle adjusting means for adjusting a swing angle of the swing member with respect to the carriage; A second swing angle adjusting means for adjusting a swing angle of the actuator base with respect to the swing member. The actuator for an optical head is characterized and. 2. The optical head actuator according to claim 1, wherein said swing angle adjusting means has an electric driving means.