Patent
1975-05-15
1977-09-27
Adams, Russell E.
354 50, 354 60R, 354 60A, 354289, G03B 708
Patent
active
040514897
ABSTRACT:
An exposure time control device of an electric camera shutter includes a brightness time conversion circuit for developing a single pulse having a width representative of the brightness of a subject to be photographed and a reference pulse generating circuit for generating reference pulses at a standard rate. A reversible counter counts the reference pulses for a period of time equal to the duration of the single pulse. Upon termination of the single pulse, a reversible counter control circuit applies control signals to the reversible counter to read-out the count stored therein for controlling the shutter exposure time. A selector switch selects the input position of the reference pulses to the reversible counter in dependence upon exposure time factors other than brightness of the subject thereby enabling the selection of the exposure time in accordance with the subject brightness as well as other factors, such as film sensitivity and diaphragm setting.
REFERENCES:
patent: 3638544 (1972-02-01), Kitai
patent: 3651744 (1972-03-01), Okada
patent: 3748979 (1973-07-01), Wada
patent: 3824608 (1974-07-01), Toyoda
TTL Cookbook by Don Lancaster, H. W. Sams & Co., 1974, p. 208.
Designing With TTL Integrated Circuits, Texas Instruments Electronics Series, 1971, p. 256.
Saito Takeo
Seki Youichi
Adams Bruce L.
Adams Russell E.
Burns Robert E.
Lobato Emmanuel J.
Seiko Koki Kabushiki Kaisha
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