Photographic camera with automatic exposure control

Details Photographic camera with automatic exposure control Photographic camera with automatic exposure control

1977-02-22

1978-09-26

Adams, Russell E.

354 60A, G03B 708

Patent

active

041174992

ABSTRACT:
Electronic circuitry for setting or controlling either one of two exposure value factors of a photographic camera, namely, the exposure time (shutter speed) and the diaphragm aperture. The circuitry includes a comparator which receives an input responsive to the film sensitivity, the brightness of the subject, and the preset selected value of the one of the two exposure factors which is to be set manually rather than automatically. The comparator is connected to a flip-flop, a counter, and a decoder in such a way as to provide a signal which can control or operate either a photographic shutter mechanism or a diaphragm aperture mechanism, and the signal also controls the lighting of luminous diodes to give a visual indication of the exposure factor value which has been determined by the circuit as the proper value for an optimum exposure. There is also provision for storing the determined exposure value for later use.

REFERENCES:
patent: 3899788 (1975-08-01), Toyoda
The TTL Data Book, Texas Instruments, Data for 74LS138, pp. 7-134 to 7-137.

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