Patent
1975-10-31
1976-11-16
Peters, Jr., Joseph F.
354 43, 354 50, 354 60R, G03B 708
Patent
active
039927148
ABSTRACT:
An electrical system wherein exposure time and diaphragm aperture form a pair of exposure-determining factors one of which is automatically determined by the system in connection with exposure of film in a camera. The electrical system forms an exposure meter which may either be separate from or built into a camera. A photosensitive structure is provided for responding to intensity of light at the object which is to be photographed in order to provide therefrom an electrical quantity corresponding to this light intensity. An exposure factor-determining circuit provides an electrical quantity corresponding to a combination of the sensitivity of the film which is to be exposed and the other of the above pair of exposure-determining factors. A differential amplifier is connected between the exposure factor-determining circuit and the photosensitive structure for receiving the electrical quantities therefrom and for providing an output corresponding to that one of the above pair of exposure-determining factors which is automatically determined. A single temperature-compensating device is electrically connected with the differential amplifier and with the photosensitive structure for compensating for the influence of temperature fluctuations. The exposure factor-determining circuit includes a pair of series-connected variable resistors adapted to be set according to the sensitivity of the film which is to be exposed and the other of the above pair of exposure-determining factors. This latter circuit also includes a constant current source for supplying current to the series-connected variable resistors.
REFERENCES:
patent: 3295424 (1967-01-01), Biker
patent: 3641890 (1972-02-01), Ono
patent: 3808463 (1974-04-01), Malder
Asahi Kogaku Kogyo Kabushiki Kaisha
Peters Jr. Joseph F.
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