| 摘要 |
PURPOSE:To reduce power consumption and improve charging efficiency while a piezoelectric actuator is charged by a method wherein the step-up circuit which steps up the charging voltage of the piezoelectric actuator, a capacitor connected to the piezoelectric actuator in series and a voltage detecting means which detects the charging voltage of the capacitor are provided. CONSTITUTION:First, when a piezoelectric actuator PA is charged, the piezoelectric actuator PA and a capacitor C1 are charged by a voltage by a voltage stepped up by a step-up circuit A. Then the voltage V2 of the capacitor C1 is detected by a voltage detecting means V. As the piezoelectric actuator PA has characteristics of a capacitor and the capacitor C1 is connected to it in series, the same charge Q is stored in the piezoelectric actuator PA and the capacitor C1. Therefore, if the capacitances of the piezoelectric actuator PA and the capacitor C1 are denoted by C and C1 and the voltages of the piezoelectric actuator PA and the capacitor C1 are denoted by V1 and V2 respectively, the following formula can be realized: Q=C(V1-V2)=C1V2. |
