Patent ID: 8391761

Claim:
A fixing device comprising: a first fixing member; a heating member; a fixing belt that forms an endless-shaped belt member supported around the first fixing member and the heating member with tension to be rotatable, and comes into contact with the heating member to be heated; and a second fixing member that forms a fixing nip region together with the fixing belt, the fixing device fixing a toner image borne on a recording medium onto the recording medium in the fixing nip region under application of heat and pressure, the heating member including: a curved heat radiating member having an outer circumferential surface in contact with the fixing belt; and a heat generating member having a heat generating layer composed of a resistance heat generating element that generates heat due to being energized and arranged to be in contact with an inside surface of the heat radiating member, the resistance heat generating element including: a paper passing region heating section forming a heat generating source part for heating a paper passing region of the fixing belt where the recording medium contacts and passes in the fixing nip region; and a detecting section that is provided to correspond to a paper non-contacting region of the recording medium of the fixing belt and connected electrically in parallel with the paper passing region heating section, the paper passing region heating section and the detecting section have an equivalent power density, and the fixing device further comprising an overheat preventing element that is provided in a vicinity of the detecting section and suppresses energization to the resistance heat generating element when temperature of the detecting section reaches a predetermined value.