| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent the output of a piezo-electric actuator from being decreased by linearizing an applied voltage waveform by charging and discharging a constant current in a piezo-electric element. <P>SOLUTION: A bridge circuit 15 for driving the piezo-electric element (driving unit 6) in a forward or reverse direction by transistors Q1-Q4 and the piezo-electric element. Current control circuits 12, 13 are disposed between the connecting point b of the transistor Q1 and the transistor Q2 and the piezo-electric element and between the connecting point c of the transistor Q3 and the transistor Q4 and the piezo-electric element. Constant-current diodes CRD1, CRD2, diodes D1, D2 and transistors Q5, Q7 disposed in parallel with them are provided in the current control circuits 12, 13. The transistors Q5, Q7 are controlled by transistors Q6, Q8. Current values are limited by the current control circuits 12, 13, thereby charging and discharging the piezo-electric element with a constant current, and a linear sawtooth-like voltage is applied to the piezo-electric element. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
