Program shutter

Details Program shutter Program shutter

1988-04-04

1989-09-05

Perkey, W. B.

G03B 7097

Patent

active

048643475

ABSTRACT:
A program shutter has a plurality of shutter sectors driven in opening and closing directions by a reversible stepping motor to define a lens aperture during an exposure operation. An arithmetic circuit calculates an exposure amount corresponding to the brightness of the object being photographed, and a counting circuit outputs a pulse count corresponding to the number of steps through which the stepping motor should be rotated based on the calculated exposure amount. A pulse circuit produces driving pulses equal in number to the number of steps determined by the counting circuit, and a time circuit determines the ON/OFF periods of the driving pulses based on the calculated exposure amount. The driving pulses are applied to the stepping motor through a driving circuit to accordingly drive the shutter sectors in the opening and closing directions during the exposure operation.

REFERENCES:
patent: 4720726 (1988-01-01), Sato et al.
patent: 4743934 (1988-05-01), Yoshida et al.
patent: 4763155 (1988-08-01), Oda et al.

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