Photography – Camera detail – Shutter
Reexamination Certificate
2005-06-09
2010-02-02
Perkey, W. B. (Department: 2862)
Photography
Camera detail
Shutter
C396S183000, C396S508000, C318S805000, C318S806000, C318S812000
Reexamination Certificate
active
07654756
ABSTRACT:
An actuator drive circuit includes a counter starting counting of a frequency-divided clock obtained by dividing a frequency of a reference clock in response to an activation signal, a D/A converter providing a converted voltage increasing gradually and stepwise in response to an output of the counter, a coil current control amplifier comparing a coil current detection voltage corresponding to a value of a coil current of the actuator with the converted voltage immediately after activation, comparing the coil current detection voltage with a coil current limitation reference voltage corresponding to an upper limit value of the coil current after the converted voltage matches the coil current limitation reference voltage, and providing an amplified output voltage prepared by amplifying a difference between the compared voltages, and a drive current output circuit providing a drive current of the actuator according to the amplified output voltage of the coil current control amplifier.
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Fenwick Warren K
Fish & Richardson P.C.
Perkey W. B.
Rohm & Co., Ltd.
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