Noise reduction system for optical record and reproduction appar

Details Noise reduction system for optical record and reproduction appar Noise reduction system for optical record and reproduction appar

1993-06-08

1995-12-12

Sikes, William L.

Radiant energy

Photocells; circuits and apparatus

Photocell controls its own optical systems

2502015, G01J 132

Patent

active

054752108

ABSTRACT:
An optical disk apparatus includes a semiconductor laser for emitting a light beam, and an automatic power control or APC circuit for driving the laser. A compound prism structure is optically coupled to the laser in an optical head section, and defines a first optical path for causing a front laser light to be projected onto a rotating optical disk and guiding a reflected light therefrom toward a first photodetector, and a second optical path for guiding a part of the reflected light toward a second photodetector. An output signal of the first photodetector is used to generate a reproduced information signal. An output signal of the second photodetector is fed back to the APC circuit as a front light monitor signal. A part of a laser control signal internally generated in the APC circuit is supplied through a wiring line to a noise reduction circuit as a laser noise monitor signal. The noise reduction circuit subtracts this noise monitor signal from the reproduced information signal to provide a noise-suppressed information signal.

REFERENCES:
patent: 4908815 (1990-03-01), Gregg et al.
patent: 5105413 (1992-04-01), Bakx
patent: 5216660 (1993-06-01), Iimura

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