Program-controlled shutter

Details Program-controlled shutter Program-controlled shutter

1975-04-17

1977-04-05

Hix, L. T.

354 23D, 354 44, G03B 714

Patent

active

040165744

ABSTRACT:
The invention discloses a program-controlled shutter wherein, depending upon the brightness of a subject, a suitable f-number and a suitable exposure time are determined by a plurality of shutter blades which are driven stepwise by a stepping motor in response to driving pulses applied thereto open the camera lens to a suitable f-number and then to close it after a suitable exposure time. To derive the electrical signal representative of the brightness of a subject, a photocell, an A-D converter, an encoder for encoding the output from a A-D converter into the binary-coded decimal signal, and a decoder for converting the output from the encoder into, for instance, a sexadecimal signal are used. In order to derive the opening pulse signal in response to which the shutter blades are opened to stop down the camera lens to a suitable f-number, a circuit for generating the voltage signal representative of the output signal from the decoder and a circuit for generating the opening pulse signal consisting of one or a plurality of pulses the number of which is dependent upon the voltage signal are used. In order to determine a suitable exposure time, an integrator in which the time when the voltage charged across a capacitor reaches a predetermined level is dependent upon the output from the decoder and a circuit which generates, in response to the output from the integrator, a closing pulse signal for reversing the stepping motor so as to close the shutter blades after a suitable exposure time which is a function of the f-number set for a given light or exposure value EV are used.

REFERENCES:
patent: 3744385 (1973-07-01), Burgarella et al.
patent: 3813680 (1974-05-01), Wagensonner et al.
patent: 3882522 (1975-05-01), Erlichman
patent: 3900855 (1975-08-01), Stempeck

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