JPH05189783A - Objective lens driving device - Google Patents

Abstract

PURPOSE:To miniaturize the above device and to improve the vibration damping effect by providing vibration damping assist members on wires for supporting a holder mounted with an optical system and attenuating vibrations by means of a viscoelastic material. CONSTITUTION:The holder fixed with an objective lens is mounted to a fixing member 6 by the wires 5. The columnar vibration damping assist members 9 having the diameter larger than the diameter of the wires 5 are fixed to the wires 5 in this constitution. The assist materials 9 exist in a space part 6b in the position slightly apart from insertion holes 6a. The viscoelastic material is packed into the space part 6b and the assist materials 9 are enclosed by this viscoelastic material. The assist materials 9 are displaced together with the wires 5 as well if the moving part tends to be resonated by its mass and the stiffness of the wires by the operation of the objective lens driving device. Strains, such as compression and shearing, are generated in the viscoelastic material at this time, but the material tends to return the displacement of the assist materials 9 while absorbing such strains and, therefore, the resonance is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens driving device of an optical pickup for recording / reproducing information on / from a disc-shaped recording medium.

[0002]

2. Description of the Related Art Generally, an audio-visual optical disk reproducing apparatus currently in use rotates a disk at a predetermined number of rotations and collects laser light emitted from a laser diode on the disk by an objective lens. The reflected light from the disc is converted into an electric signal by a photo detector, and the information recorded on the disc is reproduced. The objective lens driving device moves the objective lens so as to focus the laser light on the disk. Along with the downsizing of optical disk reproducing devices, the objective lens driving device is also downsizing.

A conventional objective lens driving device is disclosed, for example, in Japanese Utility Model Laid-Open No. 62-120425.

A conventional objective lens driving device will be described below. FIG. 3 is a partially exploded perspective view of a conventional objective lens driving device. In FIG. 3, the objective lens 1 is a holder 2
Is glued to. Reference numeral 3 is a focus coil for moving the holder 2 in the Z direction, and 4 is a tracking coil for moving it in the X direction, both of which are attached to the bobbin 2. Since the holder 2 is movable in the X and Z directions with respect to the fixing member 6, the fixing member 6 is fixed by the four wires 5 having spring characteristics.
Is attached to. The fixing member 6 is formed with an insertion hole 6a into which the wire 5 is inserted and a hole larger than the insertion hole 6a which is adjacent to the entrance of the insertion hole 6a and serves as a space 6b. The tip of the wire 5 is coated with an adhesive and inserted into the insertion hole 6 a, and is fixed to the fixing member 6. The space 6b is filled with a viscoelastic material, and the wire 5 is surrounded by this viscoelastic material (the viscoelastic material is not shown in FIG. 3). A magnet 7 and a yoke 8 are attached to the fixing member 6, and two magnets form two sets of magnetic circuits. The two sets of magnetic circuits generate magnetic flux in opposite directions in the Y direction.

The operation of the objective lens driving device constructed as described above will be described below. When an electric current flows through the focus coil 3, a force in the Z direction is generated by the magnetic flux in the magnetic circuit, and the holder 2 operates in the Z direction. Similarly, when a current flows through the tracking coil 4, a magnetic force in the magnetic circuit generates a force in the X direction, and the holder 2 operates in the X direction.

There is a resonance frequency f0 which is determined by the mass of the movable part composed of the objective lens 1, the holder 2, the focus coil 3 and the tracking coil 4 and the stiffness of the wire 5. When trying to resonate with f0, the portion of the wire 5 surrounded by the viscoelastic material is also displaced. This displacement causes strain such as compression and shear in the viscoelastic material. However, since the viscoelastic material has an action of returning the displacement of the wire 5 while absorbing this strain, resonance is suppressed and the vibration is damped. Become.

In order to downsize the objective lens driving device, the wire 5 supporting the bobbin 2 must be shortened. When the wire 5 becomes shorter, the stiffness of the wire 5 becomes larger, so that the fundamental resonance frequency f0 of the objective lens driving device becomes larger and the operation cannot be controlled. In order not to increase f0, it is necessary to reduce the wire diameter so as not to change the stiffness of the wire.

[0008]

However, in the above-mentioned conventional structure, when the diameter of the wire supporting the bobbin becomes smaller as the objective lens driving device becomes smaller, the contact area between the wire and the viscoelastic material becomes smaller, The effect of damping the basic resonance is reduced.

The present invention solves the above-mentioned conventional problems, and an object thereof is to provide a compact objective lens driving device.

[0010]

In order to solve the above-mentioned problems, an objective lens driving device of the present invention comprises a holder to which an optical system including the objective lens is attached, a fixing member, and a space between the holder and the fixing member. A support member that is attached and movably supports the holder with respect to the fixed member, a vibration damping auxiliary member that is attached to the support member and that substantially increases the surface area of the support member, and a vibration damping auxiliary member that contacts and damps vibrations. It is made of viscoelastic material.

[0011]

According to the present invention, since the vibration damping assisting member attached to the support member comes into contact with the viscoelastic material, the present invention makes contact with the viscoelastic material even if the shape of the support member changes and its surface area decreases. It is possible to secure the effect of damping the basic resonance without changing the area.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An objective lens driving device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a partially enlarged view of an objective lens driving device showing a first embodiment of the present invention. The wire 5 is fixed to the fixing member 6 as in the conventional objective lens driving device. A cylindrical vibration damping auxiliary member 9 having a diameter larger than that of the wire 5 is fixed to the wire 5. The vibration damping assisting member 9 is located at a position slightly away from the insertion hole 6a and is located in the space 6
Located within b. The space 6b is filled with a viscoelastic material, and the vibration damping auxiliary member 9 is surrounded by this viscoelastic material (the viscoelastic material is not shown in FIG. 1).

When the movable part tries to resonate due to the mass of the movable part and the stiffness of the wire due to the operation of the objective lens driving device, the vibration damping assisting member 9 is displaced together with the wire 5. This displacement causes strain such as compression and shear in the viscoelastic material. However, since the viscoelastic material acts to return the displacement of the vibration damping auxiliary member 9 while absorbing this strain, resonance is suppressed and is damped. The Rukoto.

FIG. 2 is a partially enlarged view of the objective lens driving device showing the second embodiment of the present invention, in which a fin-shaped vibration damping auxiliary member 9 is fixed to the wire 5. First
The vibration damping assisting member is surrounded by this viscoelastic material as in the above-mentioned embodiment (the viscoelastic material is not shown in FIG. 2).
Also in this embodiment, the same effect as that of the first embodiment can be obtained.

In each of the above embodiments, the vibration damping means including the viscoelastic material and the vibration damping auxiliary member is provided on the fixed member 6 side. Even if the vibration damping means is provided, the same effect can be obtained.

[0017]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, as compared with the conventional wire contacting only the viscoelastic material, the vibration damping assist member fixed to the wire contacts the viscoelastic material. The contact area with the viscoelastic material can be secured regardless of the diameter, and the effect of damping the resonance can be sufficiently obtained.
Further, the damping amount can be easily controlled by changing the shape of the vibration damping auxiliary member and changing the contact area with the viscoelastic material. Therefore, a wire having a small diameter can be used, and the wire can be shortened, so that the objective lens driving device can be downsized.

[Brief description of drawings]

FIG. 1 is a partially enlarged view of an objective lens driving device according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged view of an objective lens driving device according to a second embodiment of the present invention.

FIG. 3 is a partially exploded perspective view of a conventional objective lens driving device.

[Explanation of symbols]

 5 wire 6 fixing member 6a insertion hole 6b space 9 vibration damping auxiliary member

Claims (1)

[Claims] 1. A holder to which an optical system including an objective lens is attached, a fixing member, and a supporting member which is attached between the holder and the fixing member and movably supports the holder with respect to the fixing member. And a viscoelastic material that is attached to the support member and that substantially increases the surface area of the support member, and a viscoelastic material that comes into contact with the vibration damping auxiliary member and damps vibrations. Lens drive device.