Patent ID: 7693435

Claim:
A fixing device for fixing a toner image by giving heat to a transfer material having the toner image transferred thereto, comprising: a heat source for generating heat upon receiving a supply of power; a heating roller having the heat source mounted therein; a pressure roller disposed at a specified distance to the heating roller; a facing member disposed to face the heating roller; an endless fixing belt mounted on the facing member and the heating roller and pressed into contact with the pressure roller to form a nip portion; a temperature detecting member disposed to face the outer surface of the fixing belt for the detection of the surface temperature of the fixing belt; and an excessive temperature increase preventing member disposed to face a part of the outer circumferential surface of the heating roller where the fixing belt is not mounted for detecting the surface temperature of the heating roller and cutting off the power supply to the heat source when the surface temperature rises to or above a preset temperature.