The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 06, 1987
Filed:
Feb. 28, 1985
Masuo Ogihara, Yotsukaido, JP;
Hajime Oda, Yotsukaido, JP;
Yoichi Seki, Yotsukaido, JP;
Hiroshi Yamazaki, Yotsukaido, JP;
Seikosha Co., Ltd., Tokyo, JP;
Abstract
A program shutter has a shutter mechanism comprised of at least one sector movable in opening and closing directions in response to forward and reverse rotation of a step motor to form a lens aperture. A control unit automatically controls the shutter operation and comprises an exposure quantity storage circuit for storing exposure quantity data corresponding to the brightness of a subject being photographed, a motor control data storage circuit for storing step drive number data proportional to the exposure quantity data and interpolation quantity data corresponding to the exposure quantity data, a pulse generator circuit for generating step drive pulses and clock pulses, a first presettable counter preset with the step drive number data before opening of the sector and downcounted to zero by the drive pulses, a second presettable counter preset with the interpolation quantity data and downcounted to zero by the clock pulses beginning at a time after the first counter has downcounted to zero, a reverse drive circuit for detecting when the second counter has counted down to zero and thereafter effecting rotation of the step motor in the reverse direction, and a motor drive circuit for rotationally driving the step motor according to the drive pulses generated by the pulse generator circuit means.