| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent variation of an expansion rate of piezo-actuators due to the change in capacitance of the piezo-actuator in a drive apparatus for gradually charging the piezo-actuators to expand them, by repeating turning-on/off of charging switch. <P>SOLUTION: Upon receiving an inputted drive signal Sd, the drive apparatus 1 repeats turning-on/off of a charging switch SW1, in a state where a discharging switch SW2 is in off-state, thereby charging the piezo-actuators P1-P4 to make them expand. After that, when the input of the drive signal Sd stops, the drive apparatus 1 repeats turning-on/off of the discharge switch SW2, in a state where the charging switch SW1 is in off-state, thereby discharging the piezo-actuators P1-P4 to make them shrink. Particularly, in the charge period, the drive apparatus 1 turns on the charge switch SW1 at a fixed period and turns off the charge switch SW1, when an integral value of the current, applied to a charging path 30 in on-state of the charging switch SW1, reaches a targeted charge quantity Q. <P>COPYRIGHT: (C)2008,JPO&INPIT |
