Dynamic information storage or retrieval – Control of storage or retrieval operation by a control... – Mechanism control by the control signal
Patent
1977-06-27
1981-10-06
Cardillo, Raymond F.
Dynamic information storage or retrieval
Control of storage or retrieval operation by a control...
Mechanism control by the control signal
369 46, 369109, 369112, G11B 712, G11B 1700
Patent
active
042939445
ABSTRACT:
Information play-back apparatus comprising a laser source, a recording medium, a photodetector, a first optical system which conducts a laser beam from the laser source to an information track on the recording medium as a read spot, and a second optical system which conducts a reflected laser beam from the information track to the photodetector through an optical element having the unidirectional lens action, said optical element being arranged in a manner to define an angle of about 45 degrees relative to the direction of the information track, and said photodetector having at least four light receiving portions divided symmetrically about two axes such that at least one light receiving portion is in each of the four quadrants formed by two axes, and one of the axes is parallel to the direction of the information track.
REFERENCES:
patent: 3962721 (1976-06-01), Haan
patent: 4001494 (1977-01-01), Adler
patent: 4011400 (1977-03-01), Simons
patent: 4025949 (1977-05-01), Whitman
patent: 4037929 (1977-07-01), Bricot
Izumita Morishi
Maeda Takeshi
Sawano Susumu
Tsunoda Yoshito
Cardillo Raymond F.
Hitachi , Ltd.
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