| 摘要 |
PURPOSE:To lessen power consumption and miniaturize an apparatus by using a piezoelectric relay for precharging an input filter capacitor. CONSTITUTION:A precharging controller is composed of a bias resistor 1, a diode 2 and a piezoelectric relay 3, and a precharging part is constituted from an input filter capacitor 4, a rush current limiting resistor 5 and a contact 3a for the piezoelectric relay 3. Moreover, a power circuit 6 is connected as a load. Charging characteristics of a piezoelectric actuator of said piezoelectric relay 3 are utilized so that said relay 3 operates at a point of time when a voltage applied to a relay driving terminal rises at a time constant of a capacity C of the piezoelectric relay 3 and a resistance value R1 of the resistor 1 to reach a working voltage. Further, the piezoelectric relay 3 can take said resistance value R1 largely because of essentially requiring no steady driving current; therefore, it is possible to set a period of time for several tens of seconds only by the resistor 1.
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