| 摘要 |
PURPOSE:To always obtain stable fixability by changing a set temperature for temperature regulation of a fixing device in accordance with the amount of radiating heat after waiting-up. CONSTITUTION:The surface temperature of a fixing roll 3 of a fixing device 17 is regulated by a temperature control circuit 6 which controls turning-on/off of the output of a heater 2 in accordance with the output of a temperature sensor 5. The set temperature for this temperature regulation is set to a higher set temperature T1 for the purpose of storing heat in the fixing roll in preparation for the fall of temperature at the time of continuous copying if the amount of radiating heat of the fixing roll is large after waiting-up, but this set temperature is set to a lower set temperature T2 where fixing defects do not occur in case of continuous copying if the amount of radiating heat is small. Since the set temperature of the fixing device is changed in accordance with the amount of radiating heat, stable fixability is always attained independently of circumstance of the use or frequency in use and energy is saved.
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