Temperature control method for a fixing device

摘要

A method of controlling the surface temperature of a heat roller included in a fixing device and having a heater therein by sensing it by a thermistor. The thermistor is held in contact with the heat roller during warm-up operation and in a standby condition or spaced apart from the heat roller while a copying operation is under way. The heater is on/off controlled on the basis of a temperature measured when the thermistor is spaced apart from the heat roller. The method corrects this temperature by comparing temperatures measured in the contact and non-contact positions of the thermistor. In such a correction mode, if the difference between the two measured temperatures does not lie in a predetermined range, the method stops energizing the heater determining that an error has occurred.