JP2002050059A - Two-axis actuator - Google Patents

Abstract

(57) [Summary] [Purpose] An object of the present invention is to provide a two-axis actuator capable of moving the position of the center of gravity of a movable part without requiring a large-scale mold change of a lens holder or attaching a weight of another part. . DETAILED DESCRIPTION OF THE INVENTION A lens holder 2 for holding an objective lens 1
A support member (wire) 9 for supporting the lens holder 2 movably in two axial directions, a focusing direction and a tracking direction, with respect to the fixed part; In a biaxial actuator having a driving means for moving the lens holder, a center-of-gravity adjusting projection 12 integrally formed at a position apart from the center of gravity on the lens holder 2 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a compact disc (CD), a digital versatile disc (DV)
The present invention relates to a biaxial actuator of an optical head for recording and reproducing information on and from a recording medium such as an optical disk such as D) and a magneto-optical disk such as a mini disk (MD).

[0002]

2. Description of the Related Art An optical head for recording and reproducing information on and from a recording medium such as an optical disk such as a compact disk (CD) and a digital versatile disk (DVD), and a magneto-optical disk such as a mini disk (MD) is known. As is well known, an objective lens is held in a lens holder, the lens holder is displaceably supported, a focusing coil and a tracking coil are wound around the lens holder, and a control signal is supplied to the focusing coil and the tracking coil. A biaxial actuator for driving the objective lens in biaxial directions, focusing control for focusing the light beam on the signal recording surface of the signal recording medium, and signal tracks on the signal recording surface of the signal recording medium. Is configured to perform tracking control to follow That.

Incidentally, the objective lens driving device includes an objective lens, a focusing coil, a tracking coil, a lens, and the like, in order to prevent the occurrence of rotational vibration such as yawing and pitching which occurs in the lens holder due to driving of the objective lens or external vibration. The center of gravity (position) of the movable part including the holder is the position where the acting force due to the magnetic flux generated by the magnetic circuit and the acting force due to the magnetic flux generated by the focusing coil or the tracking coil according to the control signal, ie, the point of action. Designed to match.

Therefore, when the weight of the objective lens, the focusing coil and the tracking coil is changed, the shape of the lens holder must be changed in order to newly match the center of gravity of the movable part with the point of action. Was.

As a method for solving the above-mentioned problem without changing the shape of the lens holder, there is known a two-axis actuator in which a weight is attached to the lens holder so that the center of gravity of the movable portion matches the point of application. .

[0006]

However, in the above-described two-axis actuator, the design of the shape of the lens holder needs to be changed, and a large-scale change of a molding die is required. Need
There are drawbacks in that the number of parts and the number of assembling steps are increased, the weight of the movable portion is increased, and the drive sensitivity is reduced.

SUMMARY OF THE INVENTION An object of the present invention has been made in view of such conventional problems, and does not require a large-scale change of a mold for a lens holder or the attachment of a weight of another part. An object of the present invention is to provide a two-axis actuator that can move the position of the center of gravity.

[0008]

To achieve the above object, a biaxial actuator according to the present invention is characterized in that a projection for adjusting the center of gravity is formed on a lens holder.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention. In the figure, reference numeral 1 denotes an objective lens, and 2 denotes a lens holder on which the objective lens 1 is mounted. The lens holder has a focusing coil 3 for driving the objective lens 1 in a focusing direction.
And a tracking coil 4 for driving the objective lens 1 in the tracking direction.

Reference numerals 6 and 7 denote permanent magnets, which are magnetically connected by a yoke 8 to form a magnetic circuit. The magnetic flux generated by this magnetic circuit is linked to each of the focusing coil 3 and the tracking coil 4. The permanent magnets 6, 7, the yoke 8, the focusing coil 3, and the tracking coil 4 A drive section is formed. Therefore, when the lens holder 2 is located at a predetermined position, the focusing coil 3
By supplying a control signal to the lens holder 2, the lens holder 2 can be driven in the focusing direction. By supplying a control signal to the tracking coil 4, the lens holder 2 can be driven in the tracking direction.

The lens holder 2 is suspended and supported by four wires 9 as support members so as to be displaceable with respect to the fixed member 11. The four wires 9
Has one end fixed to the fixing member 11 and the other end connected to the lens holder 2 via the PCB substrate 10. 12
Are projections for adjusting the center of gravity, which are integrally formed around the lens holder 2 and whose number and position can be changed as required.

The objective lens 1, the lens holder 2, the focusing coil 3, the tracking coil 4, and the PC
The center of gravity of the movable portion formed by the B substrate 10 has an acting force due to a magnetic flux generated by a magnetic circuit and an acting force due to a magnetic flux generated by a focusing coil or a tracking coil according to a control signal in order to make it difficult to generate pitching and yawing. Is designed to coincide with the position where と coincides, that is, with the action point of the drive unit.

Here, the specifications of the objective lens 1, the focusing coil 3, the tracking coil 4 and the like constituting the movable part are changed. For example, the movable part is changed by changing the material of the lens or the number of turns of these coils. Of the objective lens 1, the lens holder 2, the focusing coil 3, the tracking coil 4, and the PCB 1
Since the position of the center of gravity of the movable portion constituted by 0 also moves, pitching and yawing occur. In the present invention, the number of the projections 12 formed on the upper surface of the lens holder 2 is changed in accordance with the movement of the center of gravity, so that the position of the center of gravity of the movable unit coincides with the action point of the drive unit.

The number of the protrusions 12 can be changed by preventing unnecessary portions of the protrusions from being formed from the beginning when the lens holder 2 is formed. Specifically, it is only necessary to partially cover the projection molding hole provided in the molding die for molding the lens holder 2, and the cost of correcting the die can be reduced. By changing the shape of the lens holder 2 by removing the projection as described above, the position of the center of gravity can be moved without increasing the weight of the movable part. Therefore, it is possible to prevent a decrease in drive sensitivity due to an increase in weight.

FIG. 2 shows a second embodiment of the present invention. The protrusions 12 are formed on both sides of the center of gravity of the movable portion including the objective lens 1, the lens holder 2, the focusing coil 3, the tracking coil 4, and the PCB substrate 10, and on the opposite side surfaces of the lens holder 2.

In the above description, the moving coil type objective lens driving device in which the driving coil is disposed on the lens holder side has been described. It is needless to say that the present invention is also applicable to the moving magnet type two-axis actuator provided in the above.

[0017]

As described above, according to the present invention, even when the center of gravity moves due to the change in the weight of the movable component, the number of projections added in advance can be reduced to reduce the number of projections. The center of gravity of the movable part can be made coincident with the point of action without requiring large-scale mold correction of the holder and without lowering the drive sensitivity due to the addition of the weight, making yawing and pitching less likely to occur. A biaxial actuator can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view of a first embodiment of the present invention.

FIG. 2 is a perspective view of a second embodiment of the present invention.

FIG. 3 is a perspective view showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Objective lens 2 ... Lens holder 3 ... Focusing coil 4 ... Tracking coil 6, 7 ... Permanent magnet 8 ... Yoke 9 ... Wire 10 ... PCB board 11 ..Fixing members 12 ... Projections

Claims (2)

[Claims] A lens holder for holding the objective lens; a support member for supporting the lens holder so as to be movable in two axial directions of a focusing direction and a tracking direction with respect to a fixed portion; A biaxial actuator having a driving means for moving in the biaxial direction, wherein a projection for adjusting the center of gravity integrally formed at a position apart from the center of gravity on the lens holder is provided. Biaxial actuator. 2. The biaxial actuator according to claim 1, wherein the center-of-gravity adjusting projection is formed so as to be cuttable.