1974-05-13
1976-11-02
Adams, Jr., Russell E.
354 50, 354 60R, G03B 708
Patent
active
039900860
ABSTRACT:
A shutter control circuit for a camera including a timing circuit for measuring the exposure time during which the shutter will remain open. The shutter control circuit further includes a switching circuit having a switching transistor with a collector, coupled to the timing circuit, an emitter and a base. A first constant voltage source is connected to the emitter of the switching transistor. A manual exposure control circuit includes an emitter follower circuit with a transistor complementary to the switching transistor. A second constant voltage source is also included in the manual exposure control circuit and is coupled to the emitter follower circuit. The voltage level of the second constant voltage source is capable of being manually set in accordance with the desired shutter time. The output of the emitter follower circuit is coupled to the base of the switching transistor. The shutter control circuit can include an automatic exposure control circuit which automatically determines the exposure time based upon exposure determining factors. A selection circuit is interconnected between the base of the switching transistor and between both the manual and automatic exposure control circuits for selecting one of said last two circuits to be interconnected with the switching circuit.
REFERENCES:
patent: 3625124 (1971-12-01), Miyakawa
patent: 3641890 (1972-02-01), Ono
patent: 3695157 (1972-10-01), Miyakawa
patent: 3821757 (1974-06-01), Kobori
patent: 3883882 (1975-05-01), Mori
Kawasaki Masahiro
Mori Chiharu
Adams, Jr. Russell E.
Asahi Kogaku Kogyo Kabushiki Kaisha
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