| 摘要 |
PROBLEM TO BE SOLVED: To prevent damages to a heating roller surface, or burning a paper sheet wound round a heating roller by surely detecting the abnormal temp. of the heating roller by a thermometer element of the high temp. side, between two thermometer elements equipped on a heating roller, and shutting energizing to a heater. SOLUTION: This device is allowed to provide a temp. detecting element 5, such as a thermowrite chip for high temp., in addition to the temp. detecting element 4 such as the thermowrite chip affixed on a part of periphery in the heating roller shaft direction deciding the surface temp. controller value of the heating roller 1. The detection temp. by the temp. detecting element 4 is defined as P deg.C, and the detection temp. by the temp. detecting element 5 as Q deg.C, the inequality P<Q is satisfied. Then, the device is allowed to normally monitor output signal from a sensor head 6 opposing temp. detecting elements 4 and 5, and at thermorunaway time, when detecting the temp. exceeding Q deg.C, to detect that the output signal from the sensor head 6 did not change even once within the specified time, and moreover, to stop the power supply to the heater 3 in recognizing as the abnormal temp. on heating roller 1, when the chip signal is not detected during several rotary portion.
|
