| 摘要 |
PROBLEM TO BE SOLVED: To reduce noise superposed upon a position command signal and to improve positioning accuracy of a positioning device. SOLUTION: A position command signal outputted from a control part 11 through a D/A converter 12Aa is a command signal that makes a piezo-actuator 18A slightly move. The command signal has amplitude larger than that of a command signal to be inputted to a piezo-controller 17A and becomes a signal having the original size of amplitude when it is attenuated by an attenuator 14A, and noise superposed on the command signal is also reduced at that time. A position command signal outputted from the part 11 through a D/A converter 12Ab is a command signal that makes a piezo-actuator 18A roughly move. Noise superposed on this signal is rejected with a lowpass filter 16A. The noise rejection ratio of the filter 16A is larger than the noise rejection ratio of a lowpass filter 15A. The two position command signals are synthesized by an adder 13A.
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