JPH01137226A - Galvanomirror - Google Patents

Abstract

PURPOSE:To obtain a galvanomirror with high rigidity and without requiring the feed to a movable part by using a disk-like permanent magnet of an Sm-Co compound resin coupling type, for the movable part. CONSTITUTION:Powder obtained by pulverizing an Sm-Co alloy is formed like a disk by mixing and kneading it with a nylon resin and bringing them to extrusion molding, and a movable permanent magnet 102 is formed by performing multipolar magnetization to four splits or more in the peripheral direction. Subsequently, the magnet 102, an iron back yoke 107 and a holder 103 are formed as one body with a reflecting mirror 101 inclined by 45 deg. and the holder and an outer ring of a bearing 105, and the holder and the yoke are stuck. Next, a supporting shaft 106 is engaged to an inner ring of the bearing, and the bearing is inserted and held by a collar of the shaft. On the inside of a base 108, a rotating coil 104 is provided, and a movable ball 109 is inserted and held in the outside periphery by the base and the holder. Thereafter, the neutral is adjusted by moving a neutral holding use permanent magnet 201 and a holding magnetic pole 203, and a rotational angle of the movable part is controlled by controlling a current of coils 204, 205 (not shown in the figure).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a galvanometer mirror used for tracking control of a laser beam of an optical memory device.

[Conventional technology]

Conventionally, many lens actuators used in optical heads of optical memory devices have a coil as a movable part, as shown in Japanese Patent Laid-Open No. 57-210456. Further, there are examples of a separate type optical head in which an optical system such as a laser is fixed and the mass of a moving optical system part that performs access is reduced, such as in Japanese Patent Application Laid-Open No. 61-224149.62-14331.

[Problem that the invention seeks to solve]

However, with conventional technology, depending on the power feeding method to the moving coil, the power feeding line may interfere with high-speed operation.
There are problems such as breakage of the power supply line and deterioration of adhesion due to overheating of the coil, resulting in coil deformation. In addition, since changes in coil specifications (number of turns, wire diameter, etc.) lead to changes in the mass of the movable part, it was difficult to increase speed because cut-and-try operations were often repeated in order to find the II specification of the coil.

The present invention is intended to solve these problems, and its purpose is to provide a tracking actuator for the movable part when the optical head has a separate structure in order to increase the speed of the optical memory device. The goal is to use permanent magnets to construct a galvanometer mirror that has a highly rigid structure and does not require power supply to moving parts, thereby realizing high-speed optical memory devices.

[Means for Solving the Problems] (1) The galvanomirror of the present invention is a galvanomirror having a structure in which a permanent magnet is a part of a movable part as a tracking control means for a laser beam of an optical memory device. Magnetic powder obtained by pulverizing an alloy whose basic composition is (Sm) and cobalt (Co) is mixed and kneaded with nylon resin, extruded into a disk shape, and divided into at least four parts in the circumferential direction of the disk. (b) A back yoke made of a soft magnetic material such as iron installed on one plane of the movable permanent magnet (c) The back yoke , 45° with respect to the rotation axis of the movable part such as the movable permanent magnet.
(d) A support mechanism constituted by a support shaft that freely rotatably supports a movable part consisting of the reflective mirror, the back yoke, and the movable permanent magnet. (e) A support mechanism of the movable part. As a means for holding the neutral position, a permanent magnet for neutral holding and a holding magnetic pole (f> on the opposite surface of the back yoke installation surface of the permanent magnet, provided on the outside of the movable permanent magnet,
It is characterized by comprising at least one electromagnet or coil provided as means for generating a magnetic field for controlling the rotational movement of the movable part.

〔Example〕

The present invention will be explained in detail below based on the drawings.

FIG. 1 is a plan sectional view of a galvano mirror of the present invention, in which a reflecting mirror 101 includes a movable permanent magnet 102 bonded to an Sm-Co resin, a back yoke 107, and a mirror holder 103.
The ball bearing 1 is integrated with the ball bearing 1 and is rotatable.
The outer ring of 05 is glued to the mirror holder. Furthermore, the back yoke is glued to the mirror holder. The support shaft 106 is engaged with the inner ring of the ball bearing. The ball bearing is fixed between the base 108 and the flange at the tip of the support shaft. A coil 104 for rotating the movable magnet is installed within the base. The movable part 109 is sandwiched between the base and the mirror holder at the outer periphery to reduce rotational vibration in the axial direction.

FIG. 2 is an exploded cross-sectional view of the main parts of the movable mechanism of the galvanomirror of the present invention, in which a permanent magnet 201 for neutrality holding and holding magnetic poles 202 and 203 are provided as neutrality holding means for the movable part. By moving the neutral holding permanent magnet and holding magnetic pole left and right (as shown in Figure 2), adjustments during assembly can be made more easily and effectively than when neutral holding is done by means such as springs. be. Coil 204.205 (2
05 (not shown), the rotation angle of the movable part can be controlled. Instead of this coil, an electromagnet shown in (b) is installed so that the magnetic pole part 206 is located in the neutral zone of the movable magnet, and the rotation angle can be controlled by the current flowing through the coil in the same manner as the method described above. As shown in the figure, the movable permanent magnet 102 is magnetized into 8 poles, and the number of 6 magnetized poles is 2.4.6.
．． Although 8 poles are possible, it is difficult to realize 2 poles, and when using the neutrality holding mechanism of this embodiment, 6 or 8 poles are easiest to make, and this embodiment shows an example of 8 poles. FIG. 3 shows the manufacturing process of the movable permanent magnet 102.
(Coo6t2Cu o, oJ e O, 22Zr
o, ots) An alloy with a composition of 8.2 and an average grain size of 22
A magnet composition consisting of 92% by weight of this magnetic powder and 8% by weight of nylon-12 was prepared at 200°C.
The raw material compound is kneaded and granulated to have an outer diameter of 3 to 6+11+, and then an extrusion molding machine is used to form a plate-shaped magnet oriented in the thickness direction in a magnetic field. The thus obtained plate-shaped magnet was hollowed out to obtain a disk-shaped magnet. It was formed into a disc-shaped magnet.

The maximum energy product (BH') max, coercive force bHc, and residual magnetic flux density Br of the permanent magnet are: (BH)max=7.5 (MGOe)b Hc =
5,1 (kOe)Br=5.9 (kG>) was obtained.

The permanent magnet thus obtained can be used to create a galvano mirror.
By driving the motor, the moving parts can be made smaller and lighter, and high-speed response can also be improved. Furthermore, since the magnet is a resin-bonded extrusion molded magnet, a disc-shaped magnet can be manufactured easily and economically.

FIGS. 4(a) and 4(b) are schematic diagrams of the optical system of an optical memory device using the galvanomirror of the present invention. Beam B, linear motor 4
A fixed mirror 403 fixed to the lens 02 further changes the direction of the laser beam to perform a tracking operation on the disk 404.Focusing is performed by moving an objective lens 406 up and down by a lens focusing actuator 405 mounted on a linear motor. be exposed.

〔Effect of the invention〕

As explained above, according to the present invention, by using permanent magnets in the movable part, it is possible to realize a galvanomirror with a structure that does not require power supply to the movable part, and the power supply line is disconnected during high-speed operation. There is no need to worry about such problems, the coil is prevented from deforming due to heat generation and coming into contact with the magnetic circuit, and by using a disc-shaped magnet as the movable part magnet, it has become possible to make the movable part thinner. Further, even if the coil specifications are changed, the mass of the movable part does not change, so design changes can be easily made. Furthermore, since a permanent magnet is used as the neutral holding means for the movable part, adjustment after assembly is easier and more accurate than with the conventional method using springs. Furthermore, by using an Sm--Co resin-bonded magnet as the disc-shaped movable permanent magnet, the movable part can be made smaller and lighter than other permanent magnet materials. Further, in the optical system having the configuration shown in FIG. 4, since the cross-sectional shapes of the laser beams A and B do not change, the tracking range can be widened by using the galvanometer mirror of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a plan sectional view of the galvano mirror of the present invention, FIG. 2(a) is an exploded perspective view of main parts of the galvano mirror of the present invention, FIG. 3(b) is a perspective view of an electromagnet, and FIG. 3 is a permanent magnet. FIGS. 4(a) and 4(b) are schematic diagrams of the optical system of an optical memory device using the galvanometer mirror of the present invention. Above CaL C1)) Figure 4

Claims (1)

[Claims] (1) As a tracking control means for the laser beam of an optical memory device, (a) an alloy whose basic composition is samarium (Sm) and cobalt (Co) is pulverized in a galvanometer mirror having a structure in which a permanent magnet is a part of the movable part. The obtained magnetic powder is mixed and kneaded with nylon resin, extrusion molded into a disc shape, and the disc is movable in the thickness direction with multipolar magnetization of at least four divisions in the circumferential direction of the disc. Permanent magnet (b) A back yoke made of a soft magnetic material such as iron installed on one plane of the movable permanent magnet. (c) The back yoke is at an angle of 45 degrees with respect to the rotation axis of the movable part of the movable permanent magnet. (d) a support mechanism configured by a reflecting mirror fixed at an angle of (d) a support shaft that rotatably supports a movable part consisting of the reflecting mirror, the back yoke, and the movable permanent magnet; (e) the movable part; As a means for holding the neutral position, a permanent magnet for neutral holding and a holding magnetic pole (f) are provided outside the movable permanent magnet, and a rotational movement of the movable part is provided on the opposite surface of the back yoke installation surface of the permanent magnet. A galvanometer mirror comprising at least one electromagnet or coil provided as a means for generating a magnetic field for controlling.