Patent ID: 7881632

Claim:
An image forming apparatus comprising: an apparatus main body having an image formation unit; a main power source unit that is mounted in the apparatus main body and supplies power to a heat source of a fixing device; an auxiliary power source unit detachably mounted in the apparatus main body; and a control unit configured to bring the heat source to a printable state by an operation of a warming-up, configured to stop or modulate power supplied to the heat source after a specified time has passed while the heat source of the fixing device is in the printable state, configured to stop power supplied to the heat source of the fixing device by the main power source unit, after a specified time has passed while the heat source of the fixing device is in the printable state while the auxiliary power source unit is mounted in the apparatus main body, and configured to adjust power supply of the main power source unit to the heat source of the fixing device to cause the fixing device to keep a preheat temperature, and further, after a specified time has passed with the fixing device kept at the preheat temperature, to stop the power supply of the main power source unit to the heat source of the fixing device, after the specified time has passed while the heat source of the fixing device is in the printable state while the auxiliary power source unit is not mounted in the apparatus main body.