| 摘要 |
PURPOSE: To provide a fixing device and an image forming device capale of surely reducing overshoot without making temperature at the lowermost point of roller surface temperature lower than fixing feasible lower limit temperature. CONSTITUTION: Since the roller surf ace temperature is continuously lowered in a period shown by B when copying is started, a heater is continuously turned on, but the roller surface temperature starts to rise gradually and is shifted to a temperature rising period shown by D from the lowermost point C. The shift to the temperature rising period is judged according to whether the amount of the temperature rise attains δ deg.C as shown in Figure. In the period t1 , the heater is turned on, and in the next period t2 , the heater is turned off, and such operation is repeated. Thus, the duty of the heater becomes 1/2 (at the time of t1 =t2 ) of the duty in the case the heater is fully turned on, so that the overshoot in the case copying is stopped is reduced. |
