Image forming apparatus and temperature control device for fixing unit for use therewith

摘要

There is disclosed an image forming apparatus having heating device having a heat generating resistor having a plurality of branches, conduction switching device for switching the conduction at the branch end of the heat generating resistor, and sensing device for sensing the paper size. The switching of conduction of the branch end is performed while not conducting to the heat generating resistor in accordance with the paper size sensed.