| 摘要 |
PURPOSE:To decrease the malfunction of a device which detects the temp. of a fixing device and controls the conduction of electricity to a heat source by controlling the heat source in the 1st electricity conduction mode for a prescribed time after electricity conduction and controlling the same in the 2nd conduction mode after the prescribed time. CONSTITUTION:A halogen heater 109 is provided in a fixing device of a copying machine and a thermistor 101 of a contact type is provided peripherally on a fixing roller. The surface temp. of the roller is detected by said thermistor. When the thermistor 101 exhibits a resistance value lower than a reference temp., a one-shot timer 103 is set by the output of a comparator 102. Then a driver 107 is turned on by an AND circuit 106 to turn a relay 108 on, by which the conduction of electricity to the heater 109 is started. The full wave electricity conduction in the heater is thereafter continued for a prescribed time, for example, 100 mesc. A signal which turns on and off at every 10 msec if, for example, the frequency is 50 Hz, is outputted according to the output from an oscillator 104 upon turning off of the timer 103, and the halfwave electricity is conducted to the heater 109. The malfunction of the device is thus reduced. |
