Patent ID: 7518603

Claim:
A power circuit, wherein the power circuit outputs and applies an AC voltage and a DC voltage to respective terminals of a capacitor, so as to obtain an AC output voltage shifted in accordance with the DC voltage component, the power circuit comprising: a first voltage adjuster for outputting an AC voltage; a second voltage adjuster for outputting a DC voltage; a first output terminal which is connected to one end of the capacitor and outputs the AC voltage supplied from the first voltage adjuster; a second output terminal which is connected to the other end of the capacitor and outputs the DC voltage supplied from the second voltage adjuster; a first switch for controlling connection between the first output terminal and the first voltage adjuster so as to connect the first output terminal and the first voltage adjuster or disconnect the first output terminal and the first voltage adjuster; a second switch for connecting the second terminal to the second voltage adjuster or a power source whose potential is different from the DC voltage output from the second voltage adjuster; wherein, the first switch is disconnected from the first voltage adjuster so as to set the one end of the capacitor to an electrically open state, and the second switch is connected to the power source so as to supply the potential from the power source to the other end of the capacitor when power of the power circuit is turn off.