Image forming apparatus

A fixing unit for use in an image forming apparatus, comprising:

• a heat roller, heating a toner image on a print medium;
• a heater disposed in said heat roller and supplying heat to said heat roller;
• a first temperature detector disposed in contact with a first surface area of an end portion of said heat roller outside of a second surface area of said heat roller with which the print medium passes in contact, said first temperature detector generating a first temperature data;
• a second temperature detector disposed to oppose said heat roller, said second temperature detector being in proximity to a substantially middle portion of the second surface, said second temperature detector generating a second temperature data;
• and
• a controller, controlling supply of electric power to said heater, said controller switching based on the first temperature data and the second temperature data between a first temperature control mode where said controller controls supply of electric power to said heater such that the first temperature data is equal to a first target value, and a second temperature control mode where said controller controls supply of electric power to said heater such that the second temperature data is equal to a second target value.