| 摘要 |
PURPOSE:To prevent surely incidence of fixation errors by accurately estimating a time, at which the temperature of a fixing device reaches the critical temperature for fixing. CONSTITUTION:After a copying start signal Sc is produced at a time t0 and the copying is started, the temperature of a fixing device gradually drops from T0 as the number of copied papers increases. A CPU20 calculates the temperature of the fixing device T1 at a time t1 which is a prescribed time after t0 from the detected output of a sensor 5 and further calculates the temperature of the fixing device T2 at a time t2 which is a prescribed time after t1. Then claculates an average temperature change rate between the times t1 and t2. The CPU20 finds a time ts, at which the temperature reaches the critical temperature for fixing Ts, from the average temperature change rate and, after the time ts has passed, stops a main motor 21, exposure lamp 14, electrostatic charger 13, etc., and interrupts the copying operation, so that the temperature of the fixing device can be restored. Still more, this interrupting control is made after the copying operation being made at the time ts is terminated and the copying paper is discharged to the outside machine. |
