JPS6337830A - Movable magnet type two-dimensional actuator - Google Patents

Abstract

PURPOSE:To lighten the weight of an entire mechanism by using a movable magnet type motor respectively to a focusing mechanism and a tracking mechanism as a driving source. CONSTITUTION:The focusing mechanism consists of a permanent magnet 12 mounted onto the rotary part 2a of a supporting member 2 supporting an objective lens 1 and a field coil 13 fixed on a pedestal 10 so as to surround the magnet 12. The tracking mechanism consists of a permanent magnet 14 and a field coil 15 fixed onto the pedestal 10 so as to clip the magnet 14. By conducting a current to the coil 13 to drive the magnet 12 in the up-and-down direction and the focusing control is applied for the lens 1 with respect to the surface of a recording medium. By conducting a current to the coil 15, the tracking control of the lens 1 is attained with respect to the radial direction of the surface of the recording medium. By such a constitution, since no yoke forming the magnetic circuit is required, the weight of the entire mechanism is lightened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] In an optical disc device, in order to speed up access, it is necessary to reduce the mass of the movable part.

For this purpose, it is necessary to make the so-called focusing mechanism, tracking mechanism, etc. smaller and lighter. In order to reduce the weight of these mechanisms, the present invention uses a moving magnet type motor as a drive source instead of the conventionally used moving coil type motor.

[Industrial application field]

The present invention relates to an optical disc device, and more particularly to a movable magnet type two-dimensional actuator for a focusing mechanism and a tracking mechanism.

The optical head in an optical disk device is driven by a two-dimensional actuator consisting of a focusing mechanism and a tracking mechanism, and there is a need for the optical head to be smaller and lighter due to the need for higher access.

[Conventional technology]

FIG. 2 shows a sectional view of essential parts of a conventional two-dimensional actuator. In the figure, 1 is an objective lens, 2 is a support member that integrally supports the objective lens 1, 3 is a focusing coil bonded to the support member 2, and 4 is a tracking coil bonded to the support member 2. Both coils are supported by support member 2
They are wound on top of each other on a cylindrical bobbin 5 that is integrally formed with the cylindrical bobbin 5.

Reference numeral 6 denotes a cylindrical column that also serves as a yoke for the magnetic circuit, and is fixed to the center of a U-shaped yoke 7. Permanent magnets 8.8" attached to both ends of the yoke 7 and the column 6 The focusing coil 3, which is wound around the cylindrical bobbin 5 and loosely connected to the pillar 6, moves minutely in the vertical direction along the pillar 6 by the action of the current flowing through it. ,
That is, the objective lens 1 is minutely moved in the vertical direction via the support member 2 to perform focusing control on the surface of a recording medium (not shown).

Further, the tracking coil 4 wound around the bobbin 5 rotates around the support column 6 due to the action of the current flowing through it. Performs movement (tracking control).

9 is a balancer for balancing the rotational movement.

Note that the two-dimensional actuator described above is mounted on a rough drive mechanism (not shown), and roughly drives the recording medium in the radial direction.

[Problem that the invention seeks to solve]

In a conventional moving coil type drive motor, several yokes (in this example, strut 6 and yoke 7) are used to configure the magnetic circuit.
), but since this yoke is entirely made of iron, the entire two-dimensional actuator mechanism becomes heavy, which hinders high-speed access.

The present invention was created in view of the above-mentioned drawbacks of the conventional art, and aims to provide a two-dimensional actuator that can reduce the weight of the entire mechanism.

[Means for solving problems]

The two-dimensional actuator of the present invention, as shown in FIG.
The focusing mechanism includes a first permanent magnet 12 mounted on a rotating shaft portion 2a of a support member 2 that supports an objective lens 1.
and the base 1 so as to surround the first permanent magnet 12.
0, and the tracking mechanism includes a second permanent magnet 1 attached to the end of the supporting member 2 on the opposite side to the objective lens supporting end.
4, and a second field coil 15 fixed on the base IO so as to sandwich the second permanent magnet 14 therebetween.

[Effect]

As shown in FIG. 1, since the permanent magnets 12.14 are attached to the movable part, in this type of drive motor, the strength of the magnetization of the permanent magnets 12.14 contributes to torque generation. Therefore, there is no particular need for a magnetic circuit that regulates the magnetic path of the permanent magnets, and it is only necessary to generate a magnetic field in each of the corresponding permanent magnets 12, 14 by each coil 13.15. This eliminates the need for yoke, which was a problem in the past, and reduces weight.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

In order to make the description of the configuration and operation easier to understand, the same parts will be designated by the same reference numerals throughout the design and their repeated description will be omitted.

FIG. 1 shows a sectional view of essential parts of an embodiment of the present invention.

In the figure, 10 is a base, 1) is a cylindrical coil bobbin bonded to the base 10, and 12 is a cylindrical first permanent magnet, which is attached to the rotating shaft portion 2a at the center of the support member 2. It is mounted on the coil bobbin 1) and loosely engaged with the coil bobbin 1).

13 is a first field coil for driving the first permanent magnet 12, and is a non-moving coil wound around the coil bobbin 1). In this example, two coils are shown with different winding directions, but a single coil wound in one direction may also be used. This forms a moving magnet motor.

By passing a current through the first field coil 13, the first permanent magnet 12 is driven in the vertical direction, and the objective lens 1 is integrally attached to the first permanent magnet 12 by the support member 2.
This enables focusing control on the surface of a recording medium (not shown).

Reference numeral 14 denotes a second permanent magnet, which is integrally attached to the end of the support member 2 on the side opposite to the objective lens support side. 15
is a second field coil for driving the second permanent magnet 14, and is attached to the base 10 to form a movable magnet motor.

By passing a current through the second field coil 15, the second permanent magnet 14 is rotationally driven together with the support member 2 around the cylindrical first permanent magnet 12, and the second permanent magnet 14 is driven to rotate with the support member 2.
The objective lens 1 is integrally attached to the permanent magnet 14 of
Tracking control Il is possible in the radial direction of the surface of the recording medium (not shown).

〔Effect of the invention〕

As described in detail above, the movable magnet type two-dimensional actuator of the present invention does not require a yoke that forms a conventional magnetic circuit, so the weight of the entire mechanism can be reduced, and it is effective for high-speed access.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of an embodiment of the present invention, and FIG. 2 is a sectional view of a main part of a conventional two-dimensional actuator. In FIG. 1, 1 is an objective lens, 2 is a support member, and 2a
10 is a rotating shaft portion, 10 is a base, 12 is a first permanent magnet, 13
14 represents a first field coil, 14 represents a second permanent magnet, and 15 represents a second field coil.

Claims (1)

[Scope of Claims] An optical disc device comprising a two-dimensional actuator consisting of a focusing mechanism and a tracking mechanism that performs light point control of a recording/reproducing light beam through an objective lens (1) on the surface of a recording medium, wherein the focusing mechanism is the rotating shaft portion (of the support member (2) that supports the objective lens (1)
2a), a first permanent magnet (12) attached to the first permanent magnet (12);
The base (10) surrounds the permanent magnet (12).
a first field coil (13) fixed on the support member (2); A movable magnet comprising a magnet (14) and a second field coil (15) fixed on the base (10) so as to sandwich the second permanent magnet (14) therebetween. type two-dimensional actuator.