| 摘要 |
PROBLEM TO BE SOLVED: To immediately detect the abnormality of the rising of the temp. of a heating roller caused by a defect in the abutting degree of a thermistor, the disconnection of a signal conductor, etc., by controlling the calorific value of a heating element, in accordance with the temp. of a fixing member. SOLUTION: The surface temp. of the heating roller is read by the thermistor 505 in contact with the roller. The resistance value of the thermistor 505 is changed according to the temp. of the roller. The resistance value is high at a low temp. and low at a high temp. A power supply voltage is divided with the resistance value corresponding to the temp. of the thermistor 505 and the resistance value of fixed resistance 501 and the divided voltages corresponding to the surface temperatures of the roller are outputted. An analog voltage inputted by an A/D 515 is converted into a digital value, through a multiplexer 520 by these divided voltages. Then, a CPU 517 adjusts electric energy applied to an upper heater 511 from the temperatures of thermistors for the high and low temperatures for the upper roller. |
