| 摘要 |
A fixing device, which thermally fixes an unfixed image on a recording sheet by causing the recording sheet to pass through a nip formed by a pressing member pressing against the outer circumferential surface of a heating belt that has a resistance heating layer, is provided with a temperature sensor 50 which measures temperatures of measurement regions that are set by sectioning the outer circumferential surface of the heating belt along the rotational axis. A control unit, during a printing operation, obtains a temperature difference between the maximum and minimum values of the measured temperatures for each measurement region based on the temperature distribution over the whole circumference of the outer circumferential surface of the heating belt, and judges whether an abnormality extending along the circumferential direction has occurred in the resistance heating layer by comparing the temperature difference between measurement regions of each pair (PxA8 and PxB8; PxA7 and PxB7; and the like), for each of the paper-passing region and the non-paper-passing region. This makes it possible to accurately and unerringly judge whether or not an abnormality such as a scratch has occurred in the resistance heating layer. |
