Patent ID: 8744296

Claim:
An image forming apparatus comprising: a fixing portion that heat-fixes an unfixed toner image formed on a recording material onto the recording material, the fixing portion including (i) a rotatable member, (ii) a heater that generates heat by power supplied from an alternating current power source and heats the rotatable member, and (iii) a temperature detection element that detects a temperature of the fixing portion; and a power control portion that controls the power supplied from the alternating current power source to the heater according to the temperature detected by the temperature detection element, wherein the power control portion is configured to set: a first power supply control mode for supplying power to the heater according to the detected temperature for each one control cycle, a second power supply control mode for supplying power to the heater according to the detected temperature for each one control cycle, the one control cycle of the second power supply control mode being shorter than that of the first power supply control mode, and a third power supply control mode for increasing power supplied to the heater, wherein the power control portion switches, before a leading edge of the recording material enters the fixing portion, a state of supplying the power in the first power supply control mode to a state of supplying the power in the second power supply control mode, and then switches the state of supplying the power in the second power supply control mode to a state of supplying the power in the third power supply control mode, and wherein the fixing portion fixes the unfixed toner image onto the recording material in the state of supplying the power to the heater in the first power supply control mode.