Radiant energy – Photocells; circuits and apparatus – Photocell controlled circuit
Patent
1992-09-23
1994-01-04
Westin, Edward P.
Radiant energy
Photocells; circuits and apparatus
Photocell controlled circuit
356222, G01J 144
Patent
active
052763200
ABSTRACT:
A photometering device comprises: a generator for generating an analog voltage output which varies in accordance with a light intensity of an object field and is proportional to an absolute temperature; a reference voltage generator for generating a reference voltage output proportional to an absolute temperature; a switching device for switching the analog voltage output and the reference voltage output; a single output terminal for sequentially outputting the analog voltage output and the reference voltage output switched by the switching device; and an arithmetic operation device having a single analog-digital converter for converting the analog voltage output and the reference voltage output supplied from the single output terminal to digital signals for calculating a photometering value based on the digitally converted analog voltage output and reference voltage output.
REFERENCES:
patent: 4650309 (1987-03-01), Ishida et al.
patent: 4772912 (1988-09-01), Ishida et al.
patent: 4774401 (1988-09-01), Yamada et al.
patent: 4870443 (1989-09-01), Hayakawa et al.
patent: 4969005 (1990-11-01), Tokunaga
Lee John R.
Nikon Corporation
Westin Edward P.
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