Patent ID: 8824904

Claim:
A fixing device comprising: a heating rotating body including a resistance heating layer; a pressing member forming a nip by pressing against an outer circumferential surface of the heating rotating body and causing a recording sheet to pass through the nip, the recording sheet bearing an unfixed image; a temperature measuring unit configured to measure a temperature in each of a plurality of regions extending partially along the outer surface of the heating rotating body in a circumferential direction and aligned in a direction of an axis of rotation of the heat rotating body; and a control unit configured to sample temperatures, measured by the temperature measuring unit in each of the plurality of regions, over the entire outer surface of the heating rotating body in the circumferential direction by causing the heating rotating body to rotate while supplying a predetermined amount of power to the resistance heating layer, and to determine whether an abnormality has occurred in the resistance heating layer in accordance with a difference between a maximum temperature and a minimum temperature among the sampled temperatures in a same region.