Optical disc player with focus control during search mode

Details Optical disc player with focus control during search mode Optical disc player with focus control during search mode

1982-05-04

1985-01-29

McElheny, Jr., Donald

Dynamic information storage or retrieval

Control of storage or retrieval operation by a control...

Mechanism control by the control signal

369 33, G11B 700, G11B 2112

Patent

active

044970471

ABSTRACT:
In an optical disc player for optically reading information recorded in substantially parallel tracks on the surface of a rotated record disc, an optical pick-up device includes an objective lens through which a light beam is to be focused at the surface of the record disc, and such device is shiftable, as a unit, in a radial direction of the record disc for determining the track to be scanned by the focused beam, a focusing servo control is responsive to defocusing of the light beam at the record disc surface for moving the objective lens in the direction to restore correct focus of the light beam at the record disc surface, and a gain control is provided for reducing the gain with which the focusing servo control responds to defocusing when the focused beam moves transversely across a plurality of the tracks on the record disc, for example, in the searching or random access mode of operation of the player, whereby to reduce vibratory movements of the objective lens and an undesirably harsh noise that would otherwise result from the defocusing incident to relatively rapid transverse movement of the focused beam across a number of the tracks.

REFERENCES:
patent: 4057832 (1977-11-01), Kappert
patent: 4106058 (1978-08-01), Romeas et al.
patent: 4236232 (1980-11-01), Jansen et al.
patent: 4280215 (1981-07-01), Okano
patent: 4330880 (1982-05-01), Van Dijk
patent: 4337532 (1982-06-01), Oprandi et al.
patent: 4375091 (1983-02-01), Dakin et al.
patent: 4417330 (1983-11-01), Hazel et al.

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