Dynamic information storage or retrieval – Control of storage or retrieval operation by a control... – Mechanism control by the control signal
Patent
1982-09-30
1985-10-08
Faber, Alan
Dynamic information storage or retrieval
Control of storage or retrieval operation by a control...
Mechanism control by the control signal
369 46, 369118, 369120, 250201, G11B 712
Patent
active
045464600
ABSTRACT:
A focusing arrangement for an optical disk system that inhibits focus servo loop operation when the optical head objective lens is outside of a focus range distance with respect to the disk. In the optical head a laser beam converged by the objective lens is projected onto the light-reflecting layer of an optical disk. The laser beam reflected from the light-reflecting layer of the disk is projected to the light-receiving surface of a photodetector through the objective lens, a light shielding plate, a projection lens and a cylindrical lens. The laser beam is then projected to the light-receiving surface of the photodetector, thus forming a pattern thereon. As the objective lens moves along its optical axis, the laser beam is deviated and the pattern moves in a specific direction. The photodetector comprises first and second photosensitive regions. When the objective lens lies at a distance shorter than a first predetermined distance from the light-reflecting layer, the pattern is formed on the first photosensitive region. When the objective lens lies at a distance longer than the second predetermined distance, the pattern is formed on the first photosensitive region. When the objective lens is located at a distance longer than the first predetermined distance and shorter than the second predetermined distance, the pattern is formed on the second photosensitive region.
REFERENCES:
patent: 3876841 (1975-04-01), Kramer
patent: 4011400 (1977-03-01), Simons
patent: 4079247 (1976-05-01), Bricot
patent: 4079248 (1978-03-01), Lehureau
patent: 4243848 (1981-01-01), Utsumi
patent: 4368526 (1983-01-01), Horigae
patent: 4376303 (1983-03-01), Lurie
patent: 4445208 (1984-04-01), Yamamoto
Faber Alan
Tokyo Shibaura Denki Kabushiki Kaisha
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