| 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 of the piezoelectric actuator, a second capacitor which is connected to one of capacitors of which the piezoelectric actuator is composed and a voltage detecting means which detects the charging voltage of the second capacitor are provided. CONSTITUTION:First, when a piezoelectric actuator PA is charged, the piezoelectric actuator PA (composed of a first capacitor C1 and a third capacitor C3) and a second capacitor C2 are charged by a voltage stepped up by a step-up circuit A. Then the voltage V2 of the second capacitor C2 is detected by a voltage detecting means V. As the first and second capacitors C1 and C2 are connected to each other in series, the same charge Q is stored in both the capacitors C1 and C2. Therefore, if the capacitances of the first and second capacitors C1 and C2 are denoted by C1 and C2 and the voltages of the piezoelectric actuator PA and the second capacitor C2 are denoted by V1 and V2 respectively, the following formula can be realized: Q=C1(V1-V2)=C2V2. |
