| 摘要 |
PROBLEM TO BE SOLVED: To clear a standard for the fluctuation of a power supply voltage and to prevent the shortening of the life of a heating device, without increasing a higher harmonic current by generating a heater driving signal consisting of a fixed number of turning on and off times regularly changed in each half cycle. SOLUTION: A switching element control circuit 12 receives a control signal from a CPU 13, to issue a heater temperature control signal as a heating device turning on signal for turning on a thermal fixing heater 9, to a switching element 11. Further, during the ON state of the heater temperature control signal, a heater control signal as a driving signal for controlling the thermal fixing heater 9 is issued. This heater control signal is of a signal consisting of a fixed number of turning on and off times regularly changed in each half cycle. The thermal fixing heater 9 is turned on and off with these signals by the switching element 11, so that the temp. of the outer periphery of a fixing roller 4 is adjusted to a constant temp. |
