Patent ID: 7970309
Filing Date: 2011-06-28
Classification: G03G

Abstract:
1. An image forming apparatus comprising: an image forming part that forms a toner image on a recording sheet; a fixing part that heat-fixes the toner image on the recording sheet, said fixing part including a heater that generates heat using power supplied from a commercial AC power supply and a temperature detection element that detects a temperature of the heater; and a power-control part that controls power to be supplied to the heater according to a detection temperature of the temperature detection element, wherein when power to be supplied to the heater is controlled so as to keep the detection temperature of the temperature detection element at a control target temperature, said power-control part sets an on-duty ratio according to the detection temperature for each control cycle, each of whose one period is defined as a plurality of consecutive half-waves of an AC waveform, and wherein when power to be supplied to the heater is controlled so as to keep the detection temperature at the control target temperature, if the on-duty ratio selected so as to keep the detection temperature at the control target temperature is a specific on-duty ratio and the specific on-duty ratio continues for a predetermined number of control cycles, the power-control part switches to another control cycle different in the number of consecutive half-waves of the AC waveform from a present control cycle.