Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Patent
1994-11-16
1996-08-27
Allen, Stephone
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
369 4423, G11B 700, G01J 120
Patent
active
055503683
ABSTRACT:
The optical pick-up system utilizing a knife edge method for a determining focusing error includes a light source, an optical detection unit, a beam splitter, an object lens, a knife edge, a pair of adders and a differential amplifier, wherein the optical detection unit further is provided with a first detector and a second detector, each of the first and the second detectors being equally divided to provide a pair of first and second photoelectric cells. The system is different from an optical pickup system utilizing a conventional knife edge method in that: (1) the detectors are perpendicular to each other; (2) the knife edge reflects a portion of the light beam transmitted by the beam splitter; (3) optical detection unit further includes a first adder and a second adder, each of the adders being used for summing outputs from the first and the second photoelectric cells; and the differential amplifier is used for receiving the outputs of the adders and generating a difference between the outputs from the adders as a focusing error signal.
REFERENCES:
patent: 4868377 (1989-09-01), Nishikawa
patent: 4888752 (1989-12-01), Arai
patent: 5029261 (1991-07-01), Koyama et al.
patent: 5084851 (1992-01-01), Noda et al.
patent: 5313441 (1994-05-01), Imai et al.
patent: 5374819 (1994-12-01), Kim et al.
patent: 5438562 (1995-08-01), Kobayashi et al.
Allen Stephone
Daewoo Electronics Co. Ltd.
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