JP2576481Y2 - Drive device for optical pickup actuator - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device for an optical pickup actuator used for recording / reproducing an optical disk.

[0002]

2. Description of the Related Art In recording / reproducing an optical disk, it is necessary to narrow a laser beam by an objective lens to obtain a minute spot on the disk surface and to keep it at a predetermined position. That is, focus control for focusing the objective lens on the disk surface and tracking control for following the signal groove are necessary. For this purpose, an actuator is used in the optical pickup.

FIGS. 3 and 4 are schematic views showing an example of a conventional actuator, in which only a drive unit related to the present invention is shown. The objective lens 1 is attached to an objective lens holder 2, and a longitudinal drive coil 3 is joined to a side surface of the objective lens holder 2 one by one. Further, two horizontal drive coils are attached to each of the vertical drive coils. One end of the yoke 6 is inserted into the hollow portion of the vertical drive coil, and a magnetic circuit is formed by the magnet 5 joined to the other end of the yoke 6. The side and one side of the lateral drive coil 4 are arranged.

In these figures, the arrows in the coils indicate the direction of the current, and when two vertical drive coils are connected so that the current flows in such a direction, Z Direction, that is, the objective lens moves in the focus direction,
When four transverse drive coils are connected,
That is, the objective lens moves in the tracking direction.

[0005]

In the reproduction of an ordinary optical disk, it is sufficient to obtain the driving force for translating in two directions as described above, but in the recording and reproduction of a higher density disk. In such a case, a smaller beam spot is required, and therefore, an objective lens having a large numerical aperture is used. However, when the numerical aperture of the objective lens increases,
When a beam spot is formed, coma aberration is likely to occur due to the tilt of the optical disk, and it is difficult to obtain an expected spot size. Therefore, this inclination must be corrected, and it is necessary to obtain a rotational driving force about the X axis and the Y axis in FIGS.

First, in order to obtain the rotational driving force in two directions, the vertical driving coil is divided into two parts in the Y direction in FIGS. 3 and 4 and arranged as shown in FIG. A configuration is conceivable in which the direction of the current flowing through the vertical driving coil is adjusted to obtain the Z-direction movement and the rotational driving force around the X-axis and the Y-axis. However, in this case, four vertical and horizontal drive coils are required each, which makes assembly difficult.

[0007]

According to the present invention, two longitudinal drive coils wound in a rectangular cylindrical shape are provided in a drive device disposed on both opposed side surfaces of an objective lens holder on which an objective lens is mounted. The horizontal drive coil wound in an angular flat shape is aligned with the optical axis of the objective lens, and the coil is positioned in a plane perpendicular to the optical axis of the objective lens. It is fixed to the adjacent portion of the drive coil and
A magnetic circuit comprising a U-shaped yoke and two plate-like magnets magnetized in the thickness direction and arranged corresponding to the two vertical drive coils is provided, and one side of the U-shaped yoke is provided with two vertical drive coils. The magnet which forms a reverse magnetic field in the adjacent part of the vertical drive coil and the horizontal drive coil is disposed in the magnetic gap formed by the U-shaped yoke and the two plate-shaped magnets. It was arranged.

[0008]

By adjusting the directions of the currents flowing through the four vertical drive coils, it is possible to obtain a driving force corresponding to the focus direction and the inclination of the disk in the tangential direction and the radial direction. A driving force in the tracking direction can be obtained by the driving coil.

[0009]

1 and 2 are schematic structural views showing one embodiment of the present invention. A rectangular tube-shaped vertical drive coil 3 is joined to each side of the objective lens holder 2 on which the objective lens 1 is mounted. Further, the lateral drive coils 4 each having a rectangular flat shape are attached to the joint portion. One end of the yoke 6 is inserted into a hollow portion of each of the four vertical drive coils 3, and a flat magnet magnetized in the thickness direction is fixed to the other end of the yoke 6. Further, the vertical drive coil 3 and the horizontal drive coil 4 are disposed in a magnetic gap between the yoke and the magnet in the vertical drive coil hollow portion. The magnets 5 are arranged so that the directions of the magnetic fields are opposite at two joints between the horizontal drive coil 4 and the pair of vertical drive coils 3.

With such a configuration, when a current flows in the direction of the arrow shown in the coil in the drawing, driving force in the Z direction (focus direction) and the Y direction (tracking direction) can be obtained as in a normal actuator. . Further, by appropriately selecting the direction of the current of the vertical drive coil, the rotational force around the Y axis (tangential direction of the disk) and the X
A rotational force around the axis (in the radial direction of the disk) is obtained.

[0011]

As described above, according to the present invention, a driving force for two-way parallel movement and two-way rotation can be obtained with a simple structure.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention.

FIG. 2 is a side view of FIG. 1;

FIG. 3 is a schematic configuration diagram showing a conventional example.

FIG. 4 is a side view of FIG. 3;

FIG. 5 is an explanatory view of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Objective lens 2 Objective lens holder 3 Vertical drive coil 4 Horizontal drive coil 5 Magnet 6 Yoke

Claims (1)

(57) [Scope of request for utility model registration] 1. A driving device disposed on both opposite side surfaces of an objective lens holder to which an objective lens is attached,
Two vertical drive coils wound adjacent to each other and arranged in parallel adjacent to each other with the axis of the coil coinciding with the optical axis of the objective lens, and the coil axis wound in an angular flat shape with the optical axis of the objective lens A drive unit, which is located in an orthogonal plane and is fixed to the adjacent portion by one lateral drive coil, is disposed on both sides symmetrically with respect to the objective lens. A drive device for an optical pickup actuator, wherein the drive device is installed in a magnetic circuit whose direction is reversed.