Motion-picture camera with automatic diaphragm control compensat

Details Motion-picture camera with automatic diaphragm control compensat Motion-picture camera with automatic diaphragm control compensat

1977-05-23

1978-09-26

Adams, Russell E.

Optics: motion pictures

With automatic diaphragm control

354 44, 354 60R, G03B 708

Patent

active

041165527

ABSTRACT:
A shutter mechanism alternates between an exposure phase and a reflex phase. In the reflex phase it reflects incident scene light onto a light-sensitive stage which generates a light-indicating signal. A first control pulse is generated at the start of the reflex phase, and a second control pulse at the end of the reflex phase. An integrating circuit receives the first pulse and during the reflex phase generates an integral signal dependent upon the time integral of the light-indicating signal. A signal-transmission switch is operative in response to the second pulse for transmitting the integral signal to a signal-storing stage. The signal from the signal-storing stage is used as the feedback signal to a negative-feedback control arrangement for the camera diaphragm. This feedback signal is dependent not only upon scene light but also the duration of the reflex phase. Accordingly, if the scene light remains constant but the speed of the motor driving the shutter is below or above rated speed, that is automatically compensated by a change in the feedback signal, so that the diaphragm setting takes into account the longer or shorter exposure times resulting from the shutter-motor speed deviation.

REFERENCES:
patent: 3840295 (1974-10-01), Suzuki
patent: 3912384 (1975-10-01), Wagensonner
patent: 3987462 (1976-10-01), Wagensonner
patent: 4058819 (1977-11-01), Rieder

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