Patent ID: 7738804

Claim:
An image forming apparatus, comprising: a capacitor serving as an auxiliary power source device; a fixing heater unit including a first fixing heater driven by an electric power from an external power source, and a second fixing heater provided with a halogen heater and driven by an electric power from the auxiliary power source device, the fixing heater unit being adapted to apply a heat to a fixing device for fixing a toner on a sheet; an insulating converter serving as a voltage boosting circuit configured in such a manner that a primary end of the insulating converter is connected to the auxiliary power source device, an end of a secondary end thereof is connected to the second fixing heater, and the other secondary end of the secondary end is connected to the auxiliary power source device, the voltage boosting circuit being adapted to boost an output voltage from the auxiliary power source device to output the boosted voltage to the second fixing heater; and a controller for controlling the electric power supply to the fixing heater unit, wherein the second fixing heater has an end thereof connected to the secondary end of the voltage boosting circuit, and the other end thereof connected to the auxiliary power source device, and the controller is operative to drive the first fixing heater by the electric power from the external power source, and drive the second fixing heater by the electric power from the auxiliary power source device without superimposing an output from the voltage boosting circuit in an initial stage of driving the fixing heater unit; and drive the second fixing heater by a superimposed output upon lapse of a predetermined duration while an inrush current flows to the second fixing heater, the superimposed output being obtained by superimposing the output from the voltage boosting circuit over an output from the auxiliary power source device.