Dynamic information storage or retrieval – Control of storage or retrieval operation by a control... – Mechanism control by the control signal
Patent
1982-06-21
1985-05-14
McElheny, Jr., Donald
Dynamic information storage or retrieval
Control of storage or retrieval operation by a control...
Mechanism control by the control signal
369118, G11B 700
Patent
active
045176663
ABSTRACT:
The invention provides an optical head having an objective lens whose optical axis is perpendicular to a light-reflecting layer of an optical disk. Parallel laser beams are incident on the objective lens and are focused on the light-reflecting layer. The laser beams reflected by the light-reflecting layer are transferred to a projection lens through the objective lens, and are projected on a light-receiving surface of a photodetector. An image of a beam waist of the laser beams converged by the objective lens is formed on the light-receiving surface through the objective and projection lenses. A light-shielding plate with an aperture is arranged between the projection lens and the objective lens. Only part of the laser beams which passes through an area spaced apart from a common axis of the objective and projection lenses is transmitted through its aperture. A projected pattern is moved on the light-receiving surface, depending upon a distance between the objective lens and the light-reflecting layer. The light-receiving surface has first and second photosensitive regions arranged in a direction along which the projected pattern is moved.
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patent: 4059841 (1977-11-01), Bricot et al.
patent: 4079248 (1978-03-01), Lehureau et al.
patent: 4110607 (1978-08-01), Honjo et al.
patent: 4357533 (1982-11-01), Winslow
patent: 4390781 (1983-07-01), Musha
McElheny Jr. Donald
Tokyo Shibaura Denki Kabushiki Kaisha
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