Automatic exposure controller for camera of TTL direct photometr

Details Automatic exposure controller for camera of TTL direct photometr Automatic exposure controller for camera of TTL direct photometr

1981-11-19

1983-10-11

Adams, Russell E.

354 51, G03B 708

Patent

active

044088523

ABSTRACT:
Automatic exposure controller for camera of TTL direct photometry type forms a difference between a photometric value which is obtained by determining a fixed reflection from only a first blind surface at the initiation of running of a first shutter blind and a photometric value which varies as the first blind runs, and applies the difference voltage to the base of transistor which forms a logarithmic expansion circuit. Simultaneously, the photometric value which varies as the first blind runs is applied to the emitter of the transistor. In this manner, until shutter is fully open, the logarithmic expansion circuit produces an output current of a constant magnitude while after the shutter is fully open, the voltage applied to the base is maintained constant so that the output current of the logarithmic expansion circuit varies in accordance with the brightness of an object being photographed.

REFERENCES:
patent: 4072961 (1978-02-01), Yamada
patent: 4303318 (1981-12-01), Kitauva et al.
patent: 4325615 (1982-04-01), Yamada

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