JPH01107331A - Light beam control device - Google Patents

Abstract

PURPOSE:To make a device small in size by providing a magnetic material transmitting a light to the whole of a converging means or the one part of it, generating electromagnetic force to a magnetic circuit formed between the magnetic material and the magnet of a fixing side and driving the converging means. CONSTITUTION:A Selfoc lens 9 in it's self is constituted by the transparent magnetic material. In a magnetic flux constituted by the lens 9 and the magnet 11 of a ring state provided to the outer circumference of it, a cylindrical coil 12 is provided to the inner circumference of the magnet 11 of the ring state. Then, by supplying desired current to it, the lens 9 is moved to the direction of an optical axis and a light spot formed by the lens 9 is traced according to the displacement of a disk. Thus, a yoke is unnecessary, the whole device can be made small in size and the power consumption of it can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a light beam control device for focusing a light beam in a condensing optical system for an optical video disc, a PCM audio disc, or the like.

[Prior Art] FIG. 4 is a vertical cross-sectional view showing a conventional light beam control device disclosed in, for example, Japanese Utility Model Publication No. 18-198. In the figure, (1) is a condenser lens, and (2) is a magnet, (3) is a yoke that supports magnet (2), (4) is a yoke (
3) is a non-lubricated bearing made of Teflon or other material with a small coefficient of friction installed in the cylinder, and (5) is a metal barrel to which a condensing lens (1) is attached, and this metal mirror g? (5) is supported in the cylindrical portion of the yoke (3) by a non-lubricated bearing (4) so as to be freely u-rotatable. (6) is a coil holder fixed to one end of the metal lens barrel (5), and (7) is a cylindrical coil attached to the coil holder (6).
is fitted on the outside of the cylindrical portion of the yoke (3) and is disposed opposite to the magnet (2). (8) is a light beam.

Next, the operation will be explained. The condenser lens (1) condenses the incident light beam (8) to form a light spot. This condensing lens (1) is operated in the optical axis direction (in the direction of arrow A) in order to always track the light spot according to the displacement of the disk.

The condensing lens (1) is coaxially attached to a metal lens barrel (5), and this metal lens barrel (5) is slidably supported in the optical axis direction by a non-lubricated bearing (4) with a small coefficient of friction. The coil (7) provided in the coil holder (6) fixed to the metal lens barrel (5) is connected to the magnet (2).
and a yoke (3).

Therefore, by applying a desired current to the coil (7) from a power supply device (not shown) in accordance with the displacement of the disk,
The condensing lens (1) moves in the optical axis direction under the action of the electromagnetic force generated in the magnetic circuit, and tracks the optical spot according to the displacement of the disk.

[Problems to be Solved by the Invention] Since the conventional light beam control device is configured as described above, the coil (7), the coil holder (6), the metal lens barrel (
5) has to be moved between the condenser lens (1) and the condenser lens (1), which leads to problems such as an unavoidable increase in weight and a limit to miniaturization.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a light beam control device that can be miniaturized by reducing the number of parts and can also reduce power consumption.

[Means for Solving the Problems] The light beam control device according to the present invention includes providing a magnetic old material that transmits light in the whole or a part of the light beam condensing means,
The apparatus is equipped with a driving means that generates an electromagnetic force in a magnetic circuit formed between the magnetic material and the fixed magnet to drive the light condensing means.

[Function] The light beam control device of this invention forms a magnetic circuit by the condensing means itself and the fixed part magnet, thereby eliminating the yoke, dramatically reducing the size of the movable part ffl, and making the fixed part magnet also small. It is possible to reduce costs and downsize.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, in which the same parts as in FIG. 4 are given the same reference numerals,
(9) is a SELFOC lens using transparent magnetic material.
(10) is a non-lubricant material such as Teflon coated on the circumferential surface of the SELFOC lens (9), (11) is a ring-shaped magnet, and (12) is a cylindrical fixing fixed to the inner circumferential surface of the ring-shaped magnet (11). The coil (13) is a metal non-lubricated bearing (13) that slides with the non-lubricated material (10) with low friction.
For example, aluminum material treated with hard alumite), (14
) is a holder, and this holder (14) has the ring-shaped magnet (11) fixed at one end, the metal non-lubricated bearing (13) fixed to the inner peripheral surface, and the metal non-lubricated bearing (13) A coding portion of the selfoc lens (9) of the non-lubricant material (10) is held slidably in the optical axis direction.

Next, the operation will be explained. Selfoc lens (9)
itself is made of a transparent magnetic material, and in the magnetic flux formed by the ring-shaped magnet (11) provided on its outer circumference, the cylindrical coil (provided on the inner circumference of the ring-shaped magnet (11)) By applying a desired current to 12), the SELFOC lens (9) can be moved in the optical axis direction, and the optical spot formed by the SELFOC lens (9) can be tracked according to the displacement of the disk. can.

In the above embodiment, the focus control device of the condensing lens was explained, but in FIGS. 2 and 3, the light spot is indicated by arrow A,
This shows an example of controlling in the three axial directions of B and C.
In Fig. 3, (15) is a selfoc lens (
Spring supporting 9), (16) is the iron core, (17)
is a coil provided on an orthogonal axis centered on the SELFOC lens (9).

By passing a desired current through the coil (17), the SELFOC lens (9) is moved in the directions of arrows B and C to control the light spot. Furthermore, by applying a desired current to the coil (12), the SELFOC lens (9) can be moved in the direction of arrow A as in the previous embodiment.

This embodiment is effective when applied to three-axis control for tracking control and jitter control on video discs.

Furthermore, this embodiment is not limited to video discs and PCM discs, but also printers using light beams,
Similar effects can be achieved as a light beam control device for reading and writing devices.

[Effects of the Invention] As described above, according to the present invention, a magnetic material that transmits light is provided in all or part of the light condensing means, and a magnetic circuit is formed between the light collecting means and the fixed part magnet. Therefore, the weight of the movable part can be reduced by eliminating the need for a yoke, and the fixed part magnet can also be made smaller, thereby reducing the size of the entire apparatus, thereby making it possible to obtain an inexpensive forward beam control apparatus with low power consumption.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a light beam control device according to an embodiment of the present invention, FIG. 2 is a sectional view showing another embodiment of the invention, FIG. 3 is a plan view thereof, and FIG. 4 is a conventional light beam control device. FIG. 2 is a sectional view showing a light beam control device of FIG. In the figure, (1) is a condensing means (condensing lens), (3)
is a support means (yoke), (8) is a light beam, (9) is a magnetic material (Selfoc lens), (10) is a non-lubricated material,
(11) is a magnet, and (12) is a driving means (cylindrical fixed coil). In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Agent Patent attorney Masuo Oiwa (and 2 others) Figure 1 1: Concentrating lens 8, light beam 9: SELFOC lens 10 Lubricated material 11: Magnet 12: Cylindrical fixed coil 13: Metal non-lubricated bearing 14: Holder Figure 2 17: Coil Figure 3 Figure 4 Procedural Amendment (Voluntary) Showa Year Month Date 1, Indication of Case Japanese Patent Application No. 1982-265720゛゛2 Name of Invention Beam Control Device 3, Amendment Relationship with the patent applicant's representative Moriya Shiki 4, agent address Mitsubishi Electric Corporation, 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Figure 1 8: Light beam 9: Selfoc lens 10: Non-lubricated material 11: Magnet 12: Cylindrical fixed fill 13: Metal non-lubricated bearing 14: Holder

Claims (1)

[Claims] A magnetic material is formed between a condensing means for condensing a light beam, a supporting means for supporting the condensing means, a light-transmitting magnetic material provided in all or part of the condensing means, and this magnetic material. A light beam control device comprising: a magnet provided on a fixed side so as to form a circuit; and a drive means for generating an electromagnetic force in the magnetic circuit to drive the light condensing means.