| 摘要 |
A control section 31 comprised of a CPU is connected to a position detection circuit 33 for detecting the position of a driving axis 13 by means of an MR sensor 34, a first-current charging and discharging circuit 35 for driving a piezoelectric element 14, a first-current charging and discharging circuit 36, a second-current charging and discharging circuit 37 and a third-current charging and discharging circuit 38, the last three having different values of currents for driving a piezoelectric element 16. High-speed driving and low-speed driving are alternatively used depending on a detected position. In the case of the high-speed driving, the driving axis 13 is driven at high speed by continuously generating extension/contraction displacement of a varied speed in the piezoelectric element 16 by means of the first-current charging and discharging circuit 36. In the case of the low-speed driving, the driving of the piezoelectric element 16 by means of the charging and discharging circuits 36 through 38 is combined with the operation of holding the axis 13 executed by driving the piezoelectric element 14 by means of the charging and discharging circuit 35, thereby driving the axis 13 at low speed in units of one cycle of the extension/contraction displacement of the piezoelectric element 16.
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