| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent an elongation rate of a piezoactuator from changing owing to a change in electrostatic capacitance of the piezoactuator in a driving circuit for charging and extending the piezoactuator stepwise by repeating on/off of a charging switch. <P>SOLUTION: The driving circuit 1 charges and elongates the piezoactuator P by repeating on/off of the charging switch SW1 in a state where a discharge switch SW2 is turned off when a driving signal Sd is input. Thereafter, the driving circuit discharges and contracts the piezoactuator P by repeating on/off of the discharge switch SW2 in the state where the charging switch SW1 is turned off when the driving signal Sd is not input. Particularly, in a charging period, the charging switch SW1 is turned on in a predetermined period set beforehand, and when an integral value of a current flowing through a charging path 30 upon on of the charging switch SW1 reaches a target value Vref1, the charging switch SW1 is turned off. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
