Focus detector

Details Focus detector Focus detector

1983-01-24

1985-09-24

Nelms, David C.

Radiant energy

Photocells; circuits and apparatus

Photocell controls its own optical systems

354404, G01J 120

Patent

active

045434760

ABSTRACT:
A focus detector has a photoelectric position sensor which is disposed in a proper focal plane of light beams passing through a pupil splitter having two light transmitting sections which are controllable to be made transparent alternately in an image forming optical system. Output currents from two electrodes of the photoelectric position sensor are processed to derive a signal representing the center of gravity of an image on the position sensor.
The signal is compared with the control signal for making the two light transmitting sections transparent alternately for determining an in focus or an out of focus condition and a front focus or a rear focus based on magnitude and direction of change of the signal, respectively.

REFERENCES:
patent: 3549889 (1970-12-01), Akiyama
patent: 3765765 (1973-10-01), Hefter
patent: 3815982 (1974-06-01), Wagensonner
patent: 3904870 (1975-09-01), Stauffer
patent: 4005443 (1977-01-01), Albrecht
patent: 4201456 (1980-05-01), Wolbarsht
patent: 4445029 (1984-04-01), Nagaoka et al.

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