Photography – Exposure control circuit – Having plural photocells
Patent
1996-07-10
1997-09-09
Metjahic, Safet
Photography
Exposure control circuit
Having plural photocells
2502082, 2502085, G01J 142, G03B 708
Patent
active
056665741
ABSTRACT:
Light is made incident on a pair of photo-sensors having different sensitivity characteristics. One of them has higher spectroscopic sensitivity than the other within a specified range of wavelength, but the other has spectroscopic sensitivity over a wider range of wavelength than this specified range. Both of the photo-sensors are adjusted so as to have approximately same photo-sensitivity against external background light. A difference current with intensity equal to the difference between the currents generated by this pair of photo-sensors is obtained by a subtraction circuit and is compressed by a compression circuit by a specified ratio, and the compressed current thus obtained is outputted.
REFERENCES:
patent: 5534968 (1996-07-01), Takagi
patent: 5541706 (1996-07-01), Goto
Dalakis Michael
Metjahic Safet
Rohm & Co., Ltd.
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