| 摘要 |
PURPOSE:To detect the fault of a temperature detecting element rapidly by discriminating the level of the output of the temperature detecting element and by performing display when the output of the temperature detecting element has a higher level than a reference level a constant short time after a power source is put to work. CONSTITUTION:When a thermistor 8 has a break of wire, the outputs of comparators 51 and 52 have a high level and the output of a timer circuit 38 and that of an AND gate 53 go up to the high level a constant time after a power source is put to work to turn on a transistor 72, thereby turning on a light emission diode 73. When a signal inputted to an AND gate 62 via a line 74 and the output of the AND gate 62 go down to a low level, a switching element 61 turns off to stop the feeding of electricity to a heater 7. Therefore, the feeding to the heater 7 is intercepted rapidly in response to the breaking of wire in the thermistor 8 to prevent a heat roller from overheating. |
