Abstract text

Control units supply driving signals to piezoelectric elements to control actuators such that the actuators repeatedly change their operational states between a driving state and a stop state. In addition, the control units control the actuators to enter the stop state at different timings. As such, since the actuators enter the stop state at different timings, it is possible to reduce or prevent the situation that all of the actuators stop at the same time by shifting the use timing of a power supply circuit. In addition, it is possible to reduce or prevent the situation that all of the actuators are driven at the same time and a current is supplied to all the actuators at the same time.