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:
Mar. 05, 1991
Filed:
Oct. 10, 1989
Youji Watanabe, Sagamihara, JP;
Yoshiaki Kobayashi, Nagano, JP;
Olympus Optical Co., Ltd., Tokyo, JP;
Abstract
In a diaphragm control apparatus of a camera for opening and closing aperture blades using a stepping motor, a step-out status of the stepping motor is detected if an open detecting switch for detecting a full-open status of the aperture blades does not function after a predetermined number of drive pulses necessary for resetting the aperture blades to a full-open position are supplied to the stepping motor. Normally, the stepping motor is subjected to such a slow-up control that the continuing duration of the energizing step (pulse width of an energizing pulse) is gradually reduced from the time the motor has been activated to increase a pulse rate and a driving speed. When the step-out status is detected, the pulse rate of the energizing pulse is set constant, and the driving speed of the stepping motor thereafter is fixed to a constant low speed to provide high-torque driving, and opening the aperture blades to the full-open position. Thereafter, when the aperture is closed to a given aperture value, the slow-up control is executed again, however, the pulse width of the energizing pulse is set lower than that used before detection of the step-out status, thus increasing the driving torque.