METHOD FOR CORRECTING NON-CONTACT TEMPERATURE SENSOR FOR TEMPERATURE DETECTION OF FIXING UNIT AND METHOD FOR PERFORMING TEMPERATURE CONTROL OF FIXING UNIT

摘要

PROBLEM TO BE SOLVED: To solve the problem that it is difficult to measure a correct surface temperature in the fixing unit of an electrophotographic printer due to a space generated between a temperature sensor and its peripheral surface when detecting the surface temperature of the paper-feeding area of a heating roller by using a non-contact temperature sensor which is preferable for the temperature detection in this case, and also toe solve the problem that correction values cannot be previously established when correcting the difference of temperature because the correction values vary with mounting errors of sensors. SOLUTION: The fixing unit is provided with a contact thermistor for detecting the surface temperature of the non-paper-feeding area of the heating roller and a non-contact thermistor for detecting the surface temperature of the paper-feeding area. A correction value for calculating the approximate value of a real surface temperature from a temperature detected by the non-contact temperature thermistor is determined by adding the difference of temperature detected by each thermistyor in the state where the heating roller is set at a prescribed temperature and the difference of temperature established previously between the paper-feeling area and the non-paper-feeding area. The correction value is also determined during a warming up operation performed after power op.