| 摘要 |
PURPOSE:To keep a heat roll at a temperature required for toner fixing and to prevent a heat source and a cooling fan from consuming excess power, by turning on and off a cooling fan motor power source provided near the heat source for fixing by a control signal of a power supply part which turns on and off the heat source for fixing. CONSTITUTION:When the heat source is turned on, the temperature of a heat roll 11 rises gradually, and the heat source is turned off when this temperature reaches the upper limit of a set temperature. The turning-off signal of the heat source is used as a trigger to operate a cooling fan 14, and the heat roll 11 is cooled for a set time set preliminarily by a timer. Though the surface temperature of the heat roll 11 having a large heat capacity will continue to rise after the heat source is turned off, the surface temperature of the heat roll 11 is saturated ad falls when it is slightly higher than the upper limit temperature because the cooling fan 14 starts to cool the heat roll, and the surface temperature enters into the set temperature. Thus, turning-on and off of the heat source and the cooling fan 14 are synchronized by the control signal to hold the fixing temperature of the heat roll 11 in the good state, and unnecessary power consumption is prevented. |
