Image forming apparatus including a plurality of heat generating elements

An image forming apparatus, comprising:

• a fixing device including a heater, a first rotary member, a second rotary member, and a temperature detection unit, the heater including a first heat generating element, a second heat generating element shorter in length in a longitudinal direction than the first heat generating element, and a third heat generating element shorter in length in the longitudinal direction than the second heat generating element, the first rotary member being heated by the heater, the second rotary member forming a nip portion together with the first rotary member;
• and
• a control unit configured to control a temperature of the heater based on a detection result of the temperature detection unit,
• wherein the image forming apparatus is operable in a first mode in which power is supplied to the first heat generating element and the second heat generating element and in a second mode in which power is supplied to the first heat generating element and the third heat generating element, and
• wherein a first power ratio, which is a proportion of power supplied to the first heat generating element to power supplied to the second heat generating element in the first mode, is higher than a second power ratio, which is a proportion of power supplied to the first heat generating element to power supplied to the third heat generating element in the second mode.