Patent ID: 7551871

Claim:
A power supply device comprising: a plurality of DC voltage generating circuits each configured to generate a DC voltage based on a supplied DC voltage, the plurality of DC voltage generating circuits comprising first and second DC voltage generating circuits; a capacitor configured to stabilize a DC voltage to be supplied to the first and second DC voltage generating circuits; a voltage control circuit configured to control a voltage of the capacitor so as to variably control the DC voltages from the first and second DC voltage generating circuits, the voltage control circuit being shared by the first and second DC voltage generating circuits; and a control unit configured to control a supply of a DC voltage to the capacitor and driving of the first and second DC voltage generating circuits, wherein in order to sequentially perform a stop of output from the first DC voltage generating circuit and a start of output from the second DC voltage generating circuit, the control unit stops the supply of a DC voltage to the capacitor and continues the driving of the first DC voltage generating circuit for a predetermined period of time, then the control unit stops the driving of the first DC voltage generating circuit, and then the control unit starts the supply of a DC voltage to the capacitor and starts the driving of the second DC voltage generating circuit.