Image forming apparatus

An image forming apparatus for forming an image on a recording medium, comprising:

• an image forming portion that forms an image on the recording medium;
• a fixing portion that heats the image formed on the recording medium to fix the image on the recording medium, the fixing portion including an endless belt that is in contact with the recording medium, a heater that is in contact with an inner circumferential surface of said endless belt, a back-up member that forms, in cooperation with said heater, a fixing nip portion that pinches and conveys the recording medium via said endless belt, a first temperature detection element that detects a temperature of said heater or a temperature of said endless belt, a second temperature detection element that detects a temperature of said heater or a temperature of said endless belt at a position more distant from a recording medium conveyance reference with respect to a direction perpendicular to a recording medium conveyance direction than said first temperature detection element, and a power supply control portion that can execute a first power supply control for controlling power supplied to said heater so that the temperature detected by said first temperature detection element is kept at a set temperature and a second power supply control for controlling power supplied to said heater so that the temperature detected by said second temperature detection element is kept at a set temperature;
• and
• a conveyance control portion that controls conveyance of the recording medium,
• wherein in a case where image forming is performed on the recording medium having a size that covers a position at which said second temperature detection element is disposed with respect to the direction perpendicular to the recording medium conveyance direction, if the temperature detected by said second temperature detection element rises to a predetermined temperature during execution of the first power supply control, said power supply control portion effects switching from the first power supply control to the second power supply control, and in a case where image forming is performed on the recording medium having a size that does not cover the position at which said second temperature detection element is disposed with respect to the direction perpendicular to the recording medium conveyance direction, if the temperature detected by said second temperature detection element rises to a predetermined temperature during execution of the first power supply control, said conveyance control portion executes a control for extending conveyance interval of the recording medium, while said power supply control portion maintains the first power supply control.