JPH11213408A - Actuator device - Google Patents

Abstract

(57) [Problem] To provide an actuator device which is small and has no unnecessary resonance in a high frequency range. SOLUTION: By making one magnet 9a smaller than the other magnet 9b so as to have the distribution of the lines of magnetic force 11 shown in FIG. 1, the moment around the optical axis acting on the tracking coil is balanced and unnecessary resonance in the yawing mode does not occur.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator device for an optical pickup of a disk player for projecting a light spot on a disk-shaped recording medium and optically recording / reproducing information. .

[0002]

2. Description of the Related Art In recent years, with the miniaturization of disk players, it has become necessary to provide an effective unnecessary resonance countermeasure in an actuator device of an optical pickup.

A conventional actuator device for an optical pickup will be described below. FIG. 2 is a plan view of a conventional actuator device for an optical pickup. The objective lens 1 is held at one end of a holder 2, and a focus coil 3 and a tracking coil 4 are wound and held at the other end. The holder 2 is supported by four metal wires 5, and the metal wire 5 is provided with a focus coil 3 and a tracking coil 4.
The substrate 7 laid on the fixing member 6 so as to have conduction to
Are connected and fixed to the required portions by solder 8. A drive magnet 9 and a yoke 10 are arranged opposite to each other via a focus coil 3 and a tracking coil 4, receive a magnetic field of the drive magnet 9, apply a current to the metal wire 5, and the holder 2 −Scatter direction (FIG. 3A)
It is driven in the middle (Z direction) and in the tracking direction (Y direction in FIG. 3A).

[0004]

By the way, in the actuator device, there is a problem that unnecessary resonance occurs in a high frequency range such as a pitching mode and a yawing mode.
The pitching mode and the yawing mode will be described with reference to FIG. 3 which is a schematic diagram showing a simplified actuator device. FIG. 3A is a schematic perspective view of a holder 2 on which an objective lens 1 and the like are mounted, and an actuator device in which the holder 2 is supported on a substrate 7 by four metal wires 5. The relationship between the shaft and the actuator device is also shown. Here, as shown in FIG. 3B, the phenomenon that the holder 2 rotates in the rotation direction φY around the Y axis is referred to as a pitching mode.
As shown in (c), the phenomenon of rotation in the rotation direction φZ about the Z axis is called a yawing mode.

FIG. 4 shows a conventional magnetic circuit configuration. The dashed arrow shown in FIG. Magnet 9
At the center of the magnet 9, the magnetic force line 11 goes in the X direction, but at the end of the magnet 9, the magnetic force line 11 has a Y direction component. Also,
Since the tracking coil 4 is displaced from the center in the X direction of the pair of magnets 9 having different polarities, the Y of the magnetic force line 11 is changed.
Upon receiving the magnetic field of the directional component, a force 12 acts in the direction of the arrow indicated by the thick line according to Fleming's left hand rule, and the yaw mode is generated by the force 12.

In order to avoid this phenomenon, if the tracking coil 4 is installed at the center in the X direction of the magnet 9 facing the opposite pole, no force 12 is generated.
Becomes large, and miniaturization of the actuator device becomes difficult.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a compact actuator device which eliminates unnecessary resonance in a high frequency range.

[0008]

In order to solve the above-mentioned problems, an actuator device according to the present invention is directed to an actuator device, wherein an intersection line between an opposing surface of a pair of magnets and a surface orthogonal to a center line of an optical axis of the objective lens is provided. The lengths are different.

[0009]

Embodiments of the present invention will be described below with reference to FIG. In FIG. 1, FIGS.
The same components as those of the conventional example shown in FIG. 4 are denoted by the same reference numerals. The difference from the conventional example is that the length in the Y direction of the pair of magnets 9a and b facing each other is different from each other. In FIG. 1, the length of 9a in the Y direction is smaller than that of the driving magnet 9b. An example is shown.

As described above, by making the length of one magnet 9a in the Y direction smaller than the length of the other magnet 9b in the Y direction, the distribution of the magnetic force lines 11 indicated by broken arrows in FIG. 1 is obtained. Forces 12a and 12b are generated by the Y-direction component of the magnetic field of the magnetic field lines 11, but the moments around the Z-axis are balanced, and do not cause unnecessary resonance in the yawing mode.

Although FIG. 1 shows an example in which the length of the magnet 9a in the Y direction is reduced, unnecessary resonance in the yawing mode can also be suppressed by reducing the length of the magnet 9b in the Y direction.

[0012]

As described above, in the actuator device of the optical pickup according to the present invention, the length of the intersection line between the opposing surfaces of the pair of magnets and the surface orthogonal to the center line of the optical axis of the objective lens is different. By adopting a different configuration, a moment around the optical axis acting on the tracking coil is balanced so that unnecessary resonance in the yawing mode is not generated. Therefore, it is possible to provide a compact actuator device having no unnecessary resonance in a high frequency range.

[Brief description of the drawings]

FIG. 1 is a plan view showing a magnetic field line distribution of an actuator device according to an embodiment of the present invention.

FIG. 2 is a plan view showing an example of a conventional actuator device.

3A is a perspective view showing an example of a conventional actuator device, FIG. 3B is a side view illustrating a pitching mode of the actuator device, and FIG. 3C is a side view illustrating a yawing mode of the actuator device. Figure

FIG. 4 is a plan view showing a magnetic field line distribution of a conventional actuator device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Objective lens 2 Holder 3 Focus coil 4 Tracking coil 5 Metal wire 6 Fixing member 7 Substrate 8 Solder 9 Driving magnet 10 Yoke 11 Magnetic force line 12 Force

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Naofumi Maki 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] An object lens for condensing a light beam emitted from a light source, a holder having a focus coil and a tracking coil, and a pair of opposite poles arranged to face each other via the focus coil and the tracking coil. An actuator device, comprising: a pair of magnets, wherein the lengths of the lines of intersection between the opposing surfaces of the pair of magnets and a surface orthogonal to the center line of the optical axis of the objective lens are different from each other.