| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing breakage of a fixing unit even when on/off of a power source is repeated while shortening a warm-up time. SOLUTION: The voltage of a terminal (a) voltage-divided by a thermistor 19 detecting the temperature of the fixing unit and a resistor R1 is converted into a digital value by an A/D convertor 51 to be transmitted to MPU. In addition, a switch 53 switches reference voltage 1 at the time of power source-on, reference voltage 2 in waiting, and reference voltage 3 in printing to be input to a comparator 52, and when the temperature of the fixing unit is high and the voltage at the (a) point is higher than the reference voltage of any one of positions 1-3 selected by the switch 53, the output of an AND gate circuit 54 in which a heater-on/off signal from MPU is input is at an L level since the output of the comparator 52 is at an L level. Since triac 56 i.e. a heater-on/off control switch is turned off, overheat of the fixing unit can be prevented. COPYRIGHT: (C)2008,JPO&INPIT
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