JPH04206039A - Driving device of objective lens - Google Patents

Abstract

PURPOSE:To make it possible for a bobbin to move in parallel without being distorted in a focusing direction or a tracking direction and thereby to obtain an excellent servo performance by a method wherein four or more metal wires which are fixed to the bobbin at one end and to a base at the other respectively are provided with wind parts formed by winding them one or more times, respectively. CONSTITUTION:Four metal wires 6a to 6d which are fixed at one end to a bobbin 4 holding an objective lens 3 and to a base 7 at the other respectively are provided. The metal wires 6a to 6d have wind parts 8 formed by winding them one time, respectively, and the bobbin 4 is so supported as to be movable in two directions, a focusing direction and a tracking direction. Accordingly, a torsion generated when the bobbin 4 is driven in the focusing direction or the tracking direction is suppressed by a spring force generated by the metal wires 6a to 6d themselves being wound. According to this constitution, the bobbin 4 can move in parallel in the focusing direction or the tracking direction and the stability of a servo becomes excellent.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an objective lens drive used in an optical head that optically records, reproduces, and erases high-density signals by projecting a light spot onto an information track on a disk. It is related to the device.

Conventional technology Traditionally, a light spot is focused by following the surface wobbling and eccentricity of an optical disk, and is divided into two directions: a focusing direction parallel to the optical axis direction of the objective lens, and a tracking direction perpendicular to the optical axis direction of the objective lens.
An objective lens driving device is used as a device for moving in the direction. FIG. 2 shows an example of a conventional objective lens drive device, in which two sets of U-shaped magnetic circuits are formed by a pair of magnets la and lb and a yoke 2, and are wound around a bobbin 4 that holds an objective lens 3. A portion of the focusing drive coil 5a and the four round tracking drive coils 5b and 5c are inserted into the gap of the U-shaped magnetic circuit. 4 parallel straight metal wires 6
a, 6b, 6c, and 6d, one end of which is fixed to the bobbin 4, and the other end of which is fixed to the base 7, and the bobbin 4 is supported so as to be movable in two directions: the focusing direction and the tracking direction.
The structure is such that when a current is applied to the focusing drive coil 5a, it moves in parallel in the focusing direction, and when a current is applied to the tracking drive coils 5b and 5c, it moves in parallel in the tracking direction by electromagnetic action.

Problems to be Solved by the Invention However, in the above configuration, since the bobbin 4 is held by the four parallel straight metal wires 6a, 6b, 6c, and 6d, the bobbin 4 is difficult to focus in the low frequency range. 4 when driven in direction or tracking direction
The metal wires 6a, 6b, 6c, and 6d on the parallel straight lines of the book tend to twist in the axial direction, and the servo stability is the ability to make the light spot focused by the objective lens 3 follow the surface wobbling and eccentricity of the optical disk. The problem was that the performance was poor.

Means for Solving the Problem In order to solve this problem, the present invention comprises four or more metal wires, one end of which is fixed to a bobbin that holds an objective lens, and the other end of which is fixed to a base. It has a structure in which it is wound at least once or more.

Effect: With this configuration, twisting that occurs when the bobbin is driven in the focusing or tracking direction is suppressed by the spring force generated by the winding of the metal wire itself.1. The ten bins can move the lens in parallel in the casing direction or the trunking direction, and as a result, it is possible to provide an objective lens drive device with good servo stability.

EXAMPLE Hereinafter, an example of the present invention will be described based on FIG. Note that the same members as those in the conventional example are indicated by the same symbols, and detailed explanations will be omitted. Four metal wires 6a, 6b, 6c
, 6cl each have a winding part 8 wound once,
One end is fixed to the hobbin 4, the other end is fixed to the base 7, and the hobbin 4
is supported so as to be movable in two directions: the focusing direction and the tracking direction. Further, the metal wire 6a and the metal wire 6C1, and the metal wire 6b and the metal wire 6d are arranged symmetrically with respect to a plane A that is perpendicular to the axial direction in the tracking and focusing directions and includes the axial line in the focusing direction, and The metal wires 6a and 6b, and the metal wires 6C and 6d are arranged symmetrically with respect to a plane B that is perpendicular to the axis in the focusing direction and includes the axis in the tracking direction. As a result, when twisting occurs in the bobbin 4, the spring force generated by the winding of the metal wires 6a to 6d in the winding portion 8 acts in the opposite direction to the twisting and moves the bobbin 4 in parallel. I can do it.

Effects of the Invention As described above, according to the present invention, the bobbin can be moved parallel to the focusing direction and the tracking direction without twisting, and as a result, the objective lens faithfully follows the surface wobbling and eccentricity of the optical disk, and can perform well. It is possible to obtain excellent servo performance.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an objective lens drive device showing an embodiment of the present invention, and FIG. 2 is a perspective view of a conventional objective lens drive device. la, lb...Magnet, 2...Yoke, 3...Objective lens, 4...Bobbin, 5a...Focusing drive coil ,5
b, 5c... Tracking drive coil, 6a
~6d...Metal wire, 7...Base, 8
...... Winding part. Agent's name: Agent Haruaki Koba and 2 others Figure 1 10, fb---Magnet 5b, 5cm1
-Ranoki, Gu2---Yogu Drive Coilf -Power/G one-word phrase

Claims (2)

[Claims] (1) One end is fixed to the bobbin that holds the objective lens,
An objective lens driving device comprising four or more metal wires whose other ends are fixed to a base, and a winding portion formed by winding the metal wires at least once or more. (2) The objective lens drive according to claim 1, wherein the metal wires are arranged in two drive directions of the objective lens so as to be symmetrical with respect to a plane that is perpendicular to the axis of one drive direction and includes the axis of the other drive direction. Device.