Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Patent
1993-02-22
1995-08-29
Young, W. H.
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
369112, G11B 7095
Patent
active
054467128
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to a precision angular displacement mechanism that carries out tracking for an optical record and playback apparatus using a separate optical system and the method of assembling that mechanism.
As shown in FIG. 22, in order to increase the access speed of the optical record and playback apparatus of the prior art, it is common to divide the optical system into a shifting optical system 2 that moves in the radial direction of an optical disk 1 and a stationary optical system (not illustrated) that has a light source. Here, shifting optical system 2 is composed of an object lens 3 and a mirror 4. The stationary optical system is composed of a light source and an angular displacement mechanism called a galvanomirror which does not move in relation to optical disk 1.
The galvanomirror has a reflecting mirror 6 which reflects a laser light 5 emitted from the light source in a direction A to a direction B and minutely displaces reflecting mirror 6 around a direction E. The galvanomirror also has a mechanism that tilts laser light 5 a minute angle (.theta..degree.) in direction B. As a result, laser light 5 is reflected in direction B at reflecting mirror 6. Laser light 5 is then reflected in a direction D at a mirror 4 of shifting optical system 2 and is guided to object lens 3. In addition, reflecting mirror 6 is minutely displaced in direction E. By tilting laser light 5 at a minute angle in direction B, a light spot 8 is always placed on a track 7 on optical disk 1 for tracking purposes.
An example of the galvanomirror of the prior art appears in FIGS. 23 through 26. As shown in these drawings, coils 10a and 10b, which have elliptical windings, are each attached to one side of a holder 9 having a concave cross section shape. A triangular column-shaped reflecting mirror 6 is attached to the cut-out portion of the tapered part of holder 9 by an adhesive. The tip of a holder support component 11, which is made of resin or synthetic rubber and supports holder 9, is an insert molded on the inner side of holder 9. The base end of holder support component 11 is attached to a support unit 12. In the middle of holder support component 11 is a thin hinge 11a that can change its shape elastically.
On the two sides of holder 9 is a magnetic circuit which is composed of magnets 13a and 13b and yokes 14a and 14b. There is an air gap between the magnetic circuit and coils 10a and 10b. Magnets 13a and 13b run along the longitudinal direction of coils 10a and 10b. As shown in FIG. 26, the direction of all magnification is in the same direction. As a result, the magnetic field generated by magnets 13a and 13b interlinks with coils 10a and 10b. In FIG. 26, the direction of that magnetic field is to the right. Because coils 10a and 10b are connected, the current flows in the opposite direction. When current flows through coils 10a and 10b, it follows the Fleming left hand rule. As shown in FIG. 26, a magnetic force is generated in each of coils 10a and 10b. The magnetic forces are in the opposite directions to each other.
As a result, when current flows through coils 10a and 10b, the magnetic force that acts in the opposite direction in coils 10a and 10b functions as the moment that moves the moving section, which is composed of reflecting mirror 6, holder 9 and coils 10a and 10b, around thin hinge 11a. By adjusting the direction and magnitude of the moment, it is possible to make minute adjustments to reflecting mirror 6 to adjust the direction in which the laser light will be reflected relative to shifting optical system 2.
However, in the galvanomirror described above, because thin hinge 11a of holder support component 11 is made of resin or synthetic rubber, the rate of elasticity changes with temperature. As a result, the resonant frequency fluctuates, reducing the control characteristics of reflecting mirror 6. In particular, when coils 10a and 10b are heated up due to continuous current flow, heat is conducted to holder support component 11, the elasticity coefficient of
REFERENCES:
patent: 4719614 (1988-01-01), Leterme et al.
patent: 4768180 (1988-08-01), Janssen et al.
patent: 4773055 (1988-09-01), Gijzen et al.
patent: 4799206 (1989-01-01), Imanaka
patent: 5117410 (1992-05-01), Akiyama
International Symposium on Optical Memory 1991, "Development of the Actuators for Small-Size Magneto-Optical Disk Drives", Junichi Ichihara et al., Fujitsu Lab., pp. 67-68.
Japan Mechanical Convention Papers, 1991-2, vol. 57, No. 534, "Tracking Actuators for High-Speed Magneto Optical Disk Drives", Junichi Ichihara et al., pp. 167-173.
Ishikawa Hiroyuki
Yamada Tadashi
Seiko Epson Corporation
Tsiang Harold T.
Young W. H.
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