| 摘要 |
PURPOSE:To obtain stable shock preventive effect by providing a balance weight which is put in motion in the opposite direction from a motion member and an ultrasonic motor, and driving this balance weight by the motor in synchronism with the motion of the motion member in photography. CONSTITUTION:A switch member (not shown in figure) is operated by the counterclockwise turning of a rear curtain return lock member 33 for disengaging an engagement part 19a and an engagement part 33a from each other, thereby generating a rear curtain return signal. When this signal is transmitted to an ultrasonic motor control circuit (not shown in figure), this control circuit begins to feed electricity to a piezoelectric element 41 and the rotation of a rotor 40 is so controlled that the center G of gravity of the balance weight 38 traveling direction of a shutter rear curtain at a speed where the momentum of the rear curtain is canceled. Thus, the balance weight 38 begins to travel almost simultaneously with the return traveling of the rear curtain and the center G of gravity of the balance weight 38 is so controlled into the motion at a slower speed than the shutter rear curtain.
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