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Title:
AUTOMATIC APERTURE CONTROL DEVICE
Document Type and Number:
Japanese Patent JPS6423236
Kind Code:
A
Abstract:

PURPOSE: To normally actuate a device when external oscillation occurs by providing a limiter circuit which detects the rotating velocity of an aperture and makes a counter electromotive voltage generated in a damping coil not exceed a set value in the feedback circuit of the damping coil system.

CONSTITUTION: When an exposure value detected in a video signal process circuit 4 is larger than the set value by comparing the exposure with the set value, a driving circuit 1 drives a driving coil 2 to close the aperture 3. When the external oscillation occurs, the driving circuit 1 and the driving coil 2 are operated so that the rotating velocity of the aperture 3 becomes zero by the damping coil 5. And when the counter electromotive voltage generated in the coil 5 exceeds ±50mV, the limiter circuit 6 is operated so as to limit the counter electromotive voltage. Then, the device can be normally actuated without oscillated even if the external oscillation is given.


Inventors:
Horiguchi, Shuichi
Application Number:
JP1987000179466
Publication Date:
January 25, 1989
Filing Date:
July 17, 1987
Export Citation:
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Assignee:
MATSUSHITA ELECTRIC IND CO LTD
International Classes:
G03B9/02; H04N5/238; (IPC1-7): G03B9/02; H04N5/238
Domestic Patent References:
JP61195160B
JP61062472B



 
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