Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Patent
1985-04-29
1985-12-24
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
354209, G01J 120
Patent
active
045608644
ABSTRACT:
In the device disclosed, an image formed by an optical system is scanned by an image sensor composed of independently arranged photoelectric transducing elements to produce an image scanning signal. A detecting circuit detects the variation of the brightness between the adjacent image elements as a measure of the sharpness of the image and the focus of the optical system. The focus detection accuracy is improved by non-linear transformation of the brightness variation signal with a non-linear transformation circuit that weighs the brightness variation signal on the basis of the signal level. A signal forming circuit detects the difference between the outputs of transducing elements and adds the differences to produce a comparator signal when a predetermined relationship is reached between the sharpness indication and the addition signal. An indicator indicates that the focusing condition cannot be discerned in response to the comparison signal and a control inhibits the output of the detection circuit to the indicator prior to the addition signal.
REFERENCES:
patent: 4085320 (1978-04-01), Wilwerding
patent: 4146316 (1979-03-01), Osawa
patent: 4171885 (1979-10-01), Kondo
Hosoe Kazuya
Kawabata Takashi
Kinoshita Takao
Sakane Toshio
Tsunekawa Tokuichi
Canon Kabushiki Kaisha
Nelms David C.
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