Open-loop stepper motor controlled shutter

Details Open-loop stepper motor controlled shutter Open-loop stepper motor controlled shutter

1989-12-29

1990-12-18

Hix, L. T.

354439, 354230, G03B 708

Patent

active

049789910

ABSTRACT:
An exposure control system for a camera having a scanning type shutter mechanism for forming a range of aperture areas through which a photographic image is formed includes a stepper motor and a regulator or open loop control system therefor, to actuate the shutter mechanism between its open and closed positions in correspondence with a predetermined set of aperture area defining curves selected in accordance with sensed scene brightness and subject reflectivity levels. The stepper motor is operated at a relatively low rate of speed in order to avoid shutter blade mechanism overshoot and to achieve substantially the same shutter mechanism positioning accuracy as that achieved with a closed loop control system. Employing a stepper motor together with an open loop control system for scanning shutter mechanism actuation in the above member, results in a simplified exposure control system that is both compact and relatively inexpensive.

REFERENCES:
patent: 3942183 (1976-03-01), Whiteside
patent: 4243309 (1981-01-01), Johnson et al.
patent: 4325614 (1982-04-01), Grimes
patent: 4354748 (1982-10-01), Grimes et al.
patent: 4427276 (1984-01-01), Feinerman et al.
patent: 4697908 (1987-10-01), Ogihara et al.

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