JPH0916990A - 2-axis actuator - Google Patents

Abstract

(57) [Abstract] [Purpose] To increase the driving force of the biaxial actuator in the tracking direction. [Configuration] A fixed side including a fixed portion, a yoke, and a magnet, and a lens holder for holding an objective lens,
Bobbin 7, focusing coil 6 wound around bobbin 7, hooks 10A, 10B and hooks 10A, 10B
The movable side includes a tracking coil 8 wound between the movable side, and the movable side oscillates in the optical axis and two axial directions perpendicular to the optical axis through a plurality of elastic members on the fixed side of the fixed side. It is held movably. The portions of the frames 7A and 7B formed on both ends of the bobbin 7 where the tracking coil 8 is provided are tapered portions 11 that are tapered toward the ends.
A and 11B. By winding a wire material having a large diameter in the winding space thus expanded, the driving force in the tracking direction is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxial actuator for an optical pickup which records information on an information recording medium or reproduces the information recorded on the information recording medium, and more particularly, to increase the driving force for tracking. The present invention relates to a bobbin of a biaxial actuator that can be provided with a coil.

[0002]

2. Description of the Related Art Conventionally, a biaxial actuator for an optical pickup has been used to record information on an information recording medium or reproduce information recorded on the information recording medium. The biaxial actuator can move the objective lens that focuses the light beam on the information recording surface of the information recording medium in the focusing direction (axial direction of the objective lens) and the tracking direction (direction orthogonal to the optical axis). However, in recent years, due to the increase in information recording density and the demand for high-speed operation, improvement in control performance of the optical pickup has been demanded.

Next, a conventional biaxial actuator will be described with reference to FIGS. 4 to 6.

FIG. 4 is a top view of a conventional biaxial actuator, which has a fixed portion 2, a yoke 4 and a magnet 5.
, A lens holder 1 for holding the objective lens 9, a bobbin 70, a focusing coil 6 wound on the bobbin 70, a tracking coil 80 wound between the hook 10A and the hook 10B of the bobbin 70.
And a movable side including a plurality of elastic members 3 on the fixed side of the fixed side, the movable side being perpendicular to the optical axis direction (the direction perpendicular to the paper surface in FIG. 4). It is swingably held in two axial directions indicated by the arrow D.

Next, the generation of the driving force in the focus direction and the tracking direction will be described with reference to FIG.
FIG. 5 is a sectional side view taken along the line A2--A2 of FIG.
In FIG. 5, the magnetic flux from the magnet 5 penetrates the bobbin 70 formed of a non-magnetic material as shown by an arrow B, and the yoke 4
It reaches B and returns to the yoke 4A through a magnetic circuit (not shown) composed of a magnetic material. Here, the driving force in the focus direction, that is, the optical axis direction is generated by the interaction between the magnetic flux and the current flowing through the focusing coil 6 wound around the bobbin 70. Similarly, a driving force is generated in the tracking direction, that is, in the direction of arrow D by the interaction between the magnetic flux and the current flowing in the tracking coil 80 provided on the bobbin 70.

FIG. 6 is a perspective view in which a part of the focusing coil 6 is cut away to show the structure of the bobbin and the coil, and is a part relevant to the present invention. Conventionally, a frame 70A and a frame 70B provided at both ends of a bobbin 70 having a hollow portion 20 in the center, and the frame 70A and the frame 70.
There is a body portion 70C between B, and a plurality of hooks 10A and hooks 10B opened toward the end face of the hollow portion 20 are provided in each of the frame 70A and the frame 70B. The focusing coil 6 is provided on the body portion 70C.
However, a tracking coil 80 is wound between the hook 10A and the hook 10B.

Here, as can be seen from FIG. 5 or FIG.
In the conventional bobbin 70, the space around which the tracking coil 80 is wound has been narrowly limited due to the demand for miniaturization of the biaxial actuator. However, on the other hand, there has been a demand for improvement in performance such as increase in driving force of the biaxial actuator, further miniaturization, and reduction in power consumption.

[0008]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to increase the driving force in the tracking direction without increasing the volume of the biaxial actuator, and to further improve the tracking performance.

[0009]

A frame portion at both ends of a bobbin for fixing a focusing coil and a tracking coil is tapered so as to be gradually removed toward the opening of the bobbin. The above problem is solved by providing a protrusion that opens toward the opening of the bobbin on each of the frame portions having a tapered shape portion and winding the tracking coil over the upper and lower protrusions.

[0010]

Since the winding space of the tracking coil can be set large, a large number of coils having a larger diameter can be wound, the number of ampere turns acting on the magnetic flux is increased, and a larger force is generated.

[0011]

Embodiments of the present invention will be described with reference to FIGS. FIG. 1 is a top view of an embodiment according to the present invention. The present invention differs from the prior art in the shape of the bobbin frame 7A and frame 7B for providing the tracking coil. Therefore, the other configurations are the same as those of the conventional example, the same portions are denoted by the same reference numerals as those of the conventional example, and detailed description thereof is omitted here.

FIG. 2 is a sectional side view taken along the line A1 -A1 of FIG. 1 for producing a driving force in the focusing direction, that is, the optical axis direction, and the tracking direction, that is, the arrow D direction shown in FIG. The relationship between the focusing coil 6, the tracking coil 8, the magnet 5, the magnetic flux B, and the yokes 4A and 4B is shown. One.

Here, the winding space of the tracking coil 8 which is a feature of the present invention will be described. As shown in the cross section of FIG. 2, the frame 7A and the frame 7B are inclined portions 11A.
11B, a winding space is provided with an inclination toward the open end of the hollow portion 20 of the bobbin 7. Therefore, the winding space of the tracking coil 8 increases without enlarging the bobbin 7.

FIG. 3 is a perspective view showing a structure of the bobbin and the coil of the present invention, in which a part of the focusing coil 6 wound around the body portion 7C is cut away. As described above, the inclined portion 1
Hooks 10 provided on each of frame 7A and frame 7B in the winding space increased by providing 1A and 11B.
Tracking coil 8 across A and hook 10B
However, the state is shown in which the coil is superposed on the focusing coil 6 and wound.

By providing a wide winding space as described above, a wire having a larger diameter can be used as a coil if the number of turns is the same as the conventional one. That is, since the resistance is reduced, a larger drive current can be passed and the number of ampere turns can be increased. Therefore, the tracking driving force is increased.

When a wire having the same diameter as the conventional one is used as the coil, the number of turns can be increased and the resistance can be increased. In response to this, the drive current is reduced, which contributes to the reduction in power consumption. In this case, the decrease in the drive current corresponds to the increase in the number of turns, the number of ampere turns is the same as in the conventional case, and therefore the tracking drive force does not change.

Although the winding volume of the tracking coil 8 increases as shown in the cross-sectional view of FIG. 2, the yoke 4 of the hook 10A and the hook 10B faces the yoke 4B.
It does not have to project to the B side and is sufficiently compensated in the present invention.

[0018]

As described above, according to the present invention, the space for providing the tracking coil becomes large, and the same number of turns as in the conventional case can be obtained by using a thick wire rod as the coil. That is, since the resistance of the wire rod becomes small, the current becomes large, a large ampere-turn number can be obtained, and a larger force than before can be generated.

Alternatively, when the same wire rod as the conventional one is used as the coil, the number of turns can be increased, so that the current for obtaining the same number of ampere turns as the conventional one can be made small, and the effect of reducing the power consumption is great. .

Further, as seen from the tracking coil, the inclined part is retracted toward the hollow part of the bobbin, which facilitates the work of winding the tracking coil.

[Brief description of the drawings]

FIG. 1 is a top view of a biaxial actuator according to the present invention.

2 is a cross-sectional side view taken along the line A1-A1 of FIG.

FIG. 3 is a partially broken perspective view showing a bobbin of a biaxial actuator according to the present invention.

FIG. 4 is a top view showing an example of a conventional biaxial actuator.

5 is a sectional side view taken along the line A2-A2 of FIG.

FIG. 6 shows a bobbin of a conventional biaxial actuator,
It is a perspective view with a part broken.

[Explanation of symbols]

 1 Lens Holder 2 Fixed Part 3 Elastic Member 4A, 4B Yoke 5 Magnet 6 Focusing Coil 7, 70 Bobbin 7A, 7B, 70A, 70B Frame 8, 80 Tracking Coil 9 Objective Lens 10A, 10B Hook 11A, 11B Inclined Part 20 Hollow Part

Claims (1)

[Claims] 1. A movable part comprising a bobbin provided with a focusing coil and a tracking coil,
In a biaxial actuator held by a fixed portion via an elastic member, frame portions provided at both ends of an opening of the bobbin that fixes the tracking coil are tapered toward the opening of the bobbin. Along with the deleted shape, in the frame portion having the tapered shape at both ends of the opening of the bobbin,
A biaxial actuator characterized in that a protrusion opened toward the opening of the bobbin is provided, and a tracking coil is wound around the protrusions of the frame portions at both ends and fixed.