| 摘要 |
PURPOSE:To prevent a surface temperature of a heat roller from deviating from the upper limit and the lower limit temperatures, by setting a control temperature TB at the time of a continuous copying to a specific range lower than a control tempera ture TA immediately after a power source has become ON. CONSTITUTION:As for a peripheral surface temperature of a heat roller 1, heat is taken away by a press-contacting roller 2, and the temperature falls once, but at the time point it returns to a control temperature TA and goes to stable, that is, at the time point both temperature sensors 4a, 4b go to the control temperature TA, a copy can be executed. Subsequently, the peripheral surface temperature falls once by a continuous copy, and thereafter, the peripheral surface temperature of the heat roller 1 is managed by a control temperature TB. In such a state, between the upper limit and the lower limit temperatures which are allowed, a pre-copy operation control temperature TA and a continuous copy time control temperature TB are provided, and also, they are set as 10 deg.C<TA-TB<25 deg.C. In such a way, an excessive temperature rise of a heat roller, which is apt to be generated at the time of a continuous copy is prevented, generation of an offset or a decrease of a durable service life of each member is prevented, and also, even if a continuous copy is executed, no fixing failure is generated.
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