Optical head device and manufacturing method therefor

An optical head device includes a lens holder, a wire support body which supports the lens holder through a plurality of wires, and a plate-like member on which the wire support body is mounted. The plate-like member includes a bottom plate part on which the wire support body is mounted and a rising part raised from the bottom plate part so as to face with a gap to a side face of the wire support body. The wire support body is subjected to surface bonding to the rising part with a first adhesive which is disposed within the gap and mounted on the plate-like member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Application No. 2003-297772 filed Aug. 21, 2003, which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to an optical head device that is used to record into or reproduce from an optical recording disk such as a CD or a DVD and a manufacturing method for the optical head device. More specifically, the present invention relates to a fixing structure of a wire support body that supports a lens holder holding an objective lens by using wires in the optical head device.

BACKGROUND OF THE INVENTION

An optical head device used to record into or reproduce from an optical recording disk such as a CD or a DVD is provided with an objective lens drive mechanism which drives an objective lens for converging an emitted light beam from a light source on the optical recording disk in a tracking direction and in a focusing direction.

A wire suspension type of an objective lens driving mechanism has been known in the art, in which a lens holder is supported with a plurality of wires to be driven in a tracking direction and in a focusing direction.

In the wire suspension type of objective lens drive mechanism, the respective base end portions of a plurality of wires are supported by a wire support body which is constructed as a gel pot. The wire support body is mounted together with drive magnets on a yoke (plate-like member) which is formed of a magnetic plate. The drive magnets are fixed on the yoke with an adhesive and the wire support body is fixed with a screw.

However, when the wire support body is conventionally fixed to the yoke with a screw, a tapped hole is required for screwing in the wire support body and the yoke. Thus, a space is necessary for disposing them. Further, the number of component parts increases. On the contrary, when the number of screwed places is reduced, a coating of adhesive is required for reinforcing the fixed strength and thus time and labor are imposed in the fixing operation.

When the wire support body is fixed on the yoke with an adhesive only, a screw is not required. Accordingly, the number of component parts can be reduced and the fixing operation can also be smoothly executed. However, in the conventional structure or in the case that the optical head device is further made smaller, the places to be adhered and adhesive strength are not ensured. Further, when the under face of the wire support body is adhered and fixed on the yoke again after having been fixed with an adhesive, the adhesive residue left on the adhered face prevents the wire support body from being fixed in a proper state.

SUMMARY OF THE INVENTION

In view of the problems described above, it is an object and advantage of the present invention to provide an optical head device capable of surely fixing a wire support body, which supports a lens holder through wires, on a plate-like member even though a large space is not required for fixing, and to provide a manufacturing method for the optical head device.

In order to achieve the above object and advantage, according to an embodiment of the present invention, there is provided an optical head device including a lens holder for holding an objective lens for converging an emitted light beam from a light source on an optical recording disk, a wire support body for supporting the lens holder through a plurality of wires so as to be movable in at least a tracking direction, a drive magnet for making the lens holder move in at least the tracking direction by a magnetic force generated between a drive coil attached to the lens holder and the drive magnet, and a plate-like member on which the wire support body is mounted. The plate-like member includes a bottom plate part on which the wire support body is mounted and a rising part raised from the bottom plate part so as to face with a clearance to the side face of the wire support body, and the wire support body is subjected to surface bonding to the rising part with a first adhesive disposed within the clearance and thus the wire support body is mounted on the plate-like member.

In accordance with an embodiment of the present invention, the wire support body is preferably adhered and fixed on the bottom plate part with a second adhesive at a lower end portion of the side face of the wire support body that is opposite to a side face, which is adhesively bonded to the rising part. According to the reinforcement construction described above, the fall of the wire support body is prevented even when a force larger than the strength for preventing the fall of the rising part is applied to the wire support body. In this case, a wide space is not required even when the reinforcement is performed.

In accordance with an embodiment of the present invention, the adhesive is preferably a thermosetting adhesive such as epoxy-based adhesive. The thermosetting adhesive has the advantage that its adhesive strength is high.

In accordance with an embodiment of the present invention, the rising part is preferably formed to be raised between the lens holder and the wire support body. According to the construction described above, the drive magnet can be adhesively fixed on the opposite face of the rising part with respect to a face to which the wire support body is bonded.

In accordance with an embodiment of the present invention, the rising part is formed to be cut and raised between the portion where the wire support body is disposed and the portion where the lens holder is disposed on the plate-like member. According to the construction described above, the number of component parts can be reduced.

In accordance with an embodiment of the present invention, it is preferable that the wire support body is provided with a recessed part in at least one of the upper face and the under face of the wire support body, and the first adhesive is filled into the clearance from a space between the bottom part of the recessed part and the rising part.

In accordance with an embodiment of the present invention, it is preferable that a positioning protruded part is formed on the under face of the wire support body and a positioning hole into which the positioning protruded part is fitted is formed in the bottom plate part of the plate-like member. According to the construction described above, the wire support body can be disposed at a prescribed position on the plate-like member. Further, the positional variation of the wire support body due to the shrinkage at the time of the curing of adhesive can be suppressed.

In order to achieve the above object and advantage, according to an embodiment of the present invention, there is provided a manufacturing method for an optical head device. In the manufacturing method for an optical head device, it is preferable that the lower end portion of the wire support body and the base plate part are temporarily fixed with a third adhesive before the wire support body is adhesively fixed on the plate-like member. According to the construction described above, the temporary fixing can be performed without using a jig or the like.

In the optical head device in accordance with the embodiment of the present invention, the rising part is formed in the plate-like member, and the rising part and the side face of the wire support body are subjected to surface bonding. Therefore, the wire support body can be firmly fixed on the plate-like member while the adhered place does not require a wide space in a plan view. Further, since the side face of the wire support body is used for adhesion, the adhesive is not required to be coated on the under face of the wire support body. In an alternative embodiment, the adhesive may be coated on the under face of the wire support body. In the case that the adhesive is not coated on the under face of the wire support body, even when the wire support body is detached from the plate-like member, the adhesive does not leave a residue on the under face of the wire support body. Thus, after simple cleaning, the wire support body can be fixed in a proper state even when the wire support body is fixed again. Moreover, the positional variation of the wire support body due to the shrinkage at the time of curing of the adhesive can be suppressed in comparison with the structure in which the under face of the wire support body is adhered on the plate-like member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An example of an optical head device to which the present invention is applied will be described below with reference to the accompanying drawings.

FIG. 1is a schematic construction showing the optical system of the optical head device to which the present invention is applied. As shown inFIG. 1, the optical head device1performs reproducing or recording information from or on an optical recording disk5(optical recording medium) such as a CD or a DVD. The optical head device1includes a laser light source2, a light receiving element3, and an optical system4for converging the laser beam emitted from the laser light source2on the optical recording disk5and for guiding a return light beam reflected by the optical recording disk5to the light receiving element3.

The optical system4includes, when the coordinate axes orthogonal to each other are set to be X-axis, Y-axis, and Z-axis, a diffraction element40which diffracts the laser beam “L” emitted from the laser light source2in the Y-axis direction into three beams for tracking detection, a half mirror41which reflects the laser beam “L” separated into three beams by the diffraction element40in the X-axis direction, a total reflection mirror42for upwardly bending the laser beam from the half mirror41in the Z-axis direction, a collimator lens43for converting the laser beam “L” from the total reflection mirror42into a parallel light, and an objective lens44for converging the parallel light on the record surface of the optical recording disk5. The objective lens44is servo-controlled by the objective lens drive mechanism6at a position in the tracking direction as shown by the arrow “T”, in the focusing direction as shown by the arrow “F” and in the tilt direction as shown by the arrow “Ti”.

FIG. 2(A)is a plan view showing the objective lens drive mechanism6in the optical head device1shown inFIG. 1,FIG. 2(B)is its front view,FIG. 2(C)is its bottom view andFIG. 2(D)is its right side view.FIG. 3(A)is a plan view showing a state in which a lens holder is supported by a wire support body in the objective lens drive mechanism shown inFIGS. 2(A) through 2(D),FIG. 3(B)is its front view,FIG. 3(C)is its bottom view,FIG. 3(D)is its right side view andFIG. 3(E)is its left side view.FIG. 4(A)is a plan view showing a yoke in the objective lens drive mechanism shown inFIGS. 2(A) through 2(D),FIG. 4(B)is its front view,FIG. 4(C)is its bottom view, andFIG. 4(D)is its right side view.

As shown inFIGS. 2(A) through 2(D), the objective lens drive mechanism6is an objective lens drive mechanism of a wire suspension type in which a lens holder7holding an objective lens44is supported with six wires81. The objective lens drive mechanism6includes a lens holder7, a wire support body8movably supporting the lens holder7with the six wires81, which are disposed at three positions in the vertical direction on both right and left sides of the lens holder7, in the tracking direction “T”, in the focusing direction “F” and in the tilt direction “Ti”, a yoke9for fixing and holding the wire support body8, a focusing drive coil71, tracking drive coils72and tilt drive coils (not shown), which are mounted on the lens holder7side, and drive magnets91for tracking and focusing and drive magnets92for tilt and focusing which are mounted on the yoke9and construct magnetic drive circuits for tracking, focusing and tilt together with the above-mentioned three drive coils.

As shown inFIGS. 2(A) through 2(D), andFIGS. 3(A) through 3(E), the lens holder7is provided with a body part73formed in a rectangular and tubular shape and the objective lens44is attached on the upper face of the body part73. A molded product comprising of an optical plastics is used as the objective lens44and the objective lens44is attached at the last step when the objective lens drive mechanism6is assembled in order to prevent a scratch due to assembling operations and deformation due to the temperature variation at the time of assembling. InFIGS. 3(A) through 3(E), the lens holder7is shown in the state where the objective lens44is not attached.

The focusing drive coil71is wound around on the outer peripheral portion of the body part73. The tracking drive coils72comprising of four flat coils that are mounted on the outer side of the focusing drive coil71. Further, a pair of tilt drive coils74are mounted on the inner side of the body part73. The focusing drive coil71, the tracking drive coils72and the tilt drive coils74are supplied with electrical power through the six wires81.

The wire81extends in the direction orthogonal to the optical axis of the objective lens44, and its front end portion is fixed to the side face of the lens holder7and its base portion is supported by the wire support body8.

The wire support body8supports the wires81in a state that the base portion of the wire81penetrates to a second side face83from a first side face82, which is on the lens holder7side. A printed circuit board84is attached on the second side face83and the end portion81aof the wire81is connected to the printed circuit board84with solder. Further, gel for absorbing vibration is enclosed in the inside of the wire support body8for absorbing the vibration of the wires81.

In the embodiment of the present invention, positioning protruded parts86,87are formed on the under face85of the wire support body8.

In this embodiment of the present invention, the wire support body8is formed in a U-shape in the plan view and, in the description below, the entire face located on the lens holder7side is referred to as the first side face82without distinguishing between the inner side and the outer side of the U-shaped wire support body8.

As shown inFIGS. 4(A) through 4(D), the yoke9is a plate-like member which is formed by press-working of a thin magnetic plate and is disposed so as to face to the under face75of the lens holder7. The yoke9includes a bottom plate part93on which the wire support body8is mounted, outer yokes94a,94b,94c,94dwhich are cut and raised from the bottom plate part93, and an inner yoke95fixed to the bottom plate part93with caulking. The drive magnets91for tracking and focusing are mounted on the outer yokes94a,94band the drive magnets92for tilt and focusing are mounted on the outer yokes94c,94d.

The bottom plate part93is provided with a circular hole96into which the positioning protruded part86of the wire support body8is fitted and an elliptical hole97into which the positioning protruded part87is fitted as the positioning part for positioning the wire support body8. Therefore, the wire support body8can be positioned with respect to the yoke9such that the positioning protruded part86fits into the circular hole96and the positioning protruded part87fits into the elliptical hole97. In this state, the first side face82of the wire support body8faces to the outer yoke94awith a gap space “G” of a prescribed clearance (seeFIG. 5(B)).

FIG. 5(A)is a perspective view showing the fixed state of the wire support body8and the yoke9andFIG. 5(B)is its cross-sectional view.

In the embodiment of the present invention, the wire support body8and the yoke9are subjected to surface bonding with a thermosetting adhesive10(first adhesive) such as an epoxy adhesive which is filled in the clearance “G” formed between the surface of the first side face82of the wire support body8and the surface of the outer yoke94a.

Recessed parts88a,88bare formed on the respective upper and under faces of the wire support body8and the thermosetting adhesive10is filled in the gap “G” from the space between the respective inner bottom faces880of the recessed parts88a,88band the outer yoke94a.

Further, the lower end part of the printed circuit board84constructing the second side face83of the wire support body8and the bottom plate part93of the yoke9are subjected to surface bonding with a thermosetting adhesive10(second adhesive) such as an epoxy adhesive.

The steps for mounting the wire support body8on the yoke9having the fixing structure described above will be described below. First, the wire support body8is disposed on the bottom plate part93of the yoke9. At this time, the positioning protruded parts86,87of the wire support body8are fitted into the circular hole96and the elliptical hole97for positioning the yoke9and thus the wire support body8is disposed at the predetermined position on the yoke9.

Next, an ultraviolet curing adhesive11(third adhesive) is coated and cured so as to cover the lower end part89of the side face, which is perpendicular to the first side face82and the second side face83of the wire support body8, and the bottom plate part93of the yoke9to temporarily fix the wire support body8on the yoke9.

After the wire support body8is temporarily fixed, a thermosetting adhesive10(second adhesive) is coated in a spotted form between the inner bottom faces880of the recessed parts88a,88bof the wire support body8and the outer yoke94aand the thermosetting adhesive10is flowed into the gap “G” between the first side face82of the wire support body8and the outer yoke94a.

Also, the thermosetting adhesive10is coated so as to cover the lower end part of the printed circuit board84, which constructs the second side face83of the wire support body8, and the bottom plate part93of the yoke9.

Next, the thermosetting adhesive10is thermally cured under the condition at the temperature of 90° C. for 30 minutes to adhesively fix the wire support body8on the yoke9.

After then, the objective lens44is adhered and fixed to the lens holder7.

As described above, in the optical head device1in accordance with the embodiment of the present invention, the wire support body8and the yoke9are subjected to surface bonding with a thermosetting adhesive10, that is, the face of the wire support body8is adhered on the face of the outer yoke94a, which is raised from the bottom plate part93of the yoke9, with the thermosetting adhesive10in a face to face relation. Moreover, the adhesive strength of the thermosetting adhesive10is high. Accordingly, the wire support body8can be fixed on the yoke9firmly and such an adhered place is not required to occupy a wide space in the plan view. In addition, the first side face82of the wire support body8is used for adhesion and the adhesive is not applied to the under face of the wire support body8. Consequently, even when the wire support body8is detached from the yoke9, the adhesive is not remained on the under surface of the wire support body8. Thus the wire support body8can be fixed in a proper state even when the wire support body8is fixed again after simple cleaning. Moreover, the positional variation of the wire support body8due to the shrinkage at the time of curing of the adhesive can be suppressed in comparison with the structure in which the under face of the wire support body8is adhered on the face of the yoke9.

In the embodiment of the present invention, the first side face82of the wire support body8is subjected to surface bonding with the outer yoke94aof the yoke9. Therefore, the adhesive strength between the wire support body8and the yoke9can be enhanced in comparison with the case that the under face of the wire support body8is adhered on the yoke9. Further, the thermosetting adhesive10is not coated between the surface of the bottom plate part93of the yoke9and the under face of the wire support body8. Therefore, the positional variation of the wire support body8due to the shrinkage at the time of curing of the adhesive can be reduced.

Moreover, the wire support body8is bonded to the bottom plate part93of the yoke9with the thermosetting adhesive10at the lower end portion on the second side face83side which is opposite to the first side face82. Therefore, even when a force, which is larger than the strength for preventing the fall of the outer yoke94a, is applied thereto, the fall of the wire support body8can be prevented.

Moreover, in the embodiment of the present invention, the rising part for performing the surface bonding with the first side face82of the wire support body8is formed by cutting and bending upward as the outer yoke94abetween the lens holder7and the wire support body8. Accordingly, since the both faces of the outer yoke94acan be utilized, the simplification of structure and the reduction of the number of component parts can be attained.

Further, since the wire support body8is temporarily fixed to the yoke9with the ultraviolet curing type adhesive11or the like, a jig for temporary fixing is not required to be attached to and detached from the wire support body8and the yoke9under the condition that they are positioned each other, and thus the thermosetting adhesive10can be coated. Therefore, the coating operation is simple.

As described above, in the optical head device of the present invention, the rising part is formed in the plate-like member, and the rising part and the side face of the wire support body are subjected to surface bonding. Therefore, the wire support body can be firmly fixed on the plate-like member while the adhered place does not require a wide space in the plan view. Further, since the side face of the wire support body is used for adhesion, the adhesive may not be required to be coated on the under face of the wire support body. In the case that the adhesive is not coated on the under face of the wire support body, even when the wire support body is detached from the plate-like member, the adhesive does not remain on the under face of the wire support body. Thus the wire support body can be fixed in a proper state even when the wire support body is fixed again after simple cleaning. Moreover, the positional variation of the wire support body due to the shrinkage at the time of curing of the adhesive can be suppressed in comparison with the structure in which the under face of the wire support body is adhered on the plate-like member.