Patent ID: 8849141

Claim:
An image forming apparatus configured to form an image on a recording sheet, the image forming apparatus comprising: a fixing device configured to thermally fix the image on the recording sheet, the fixing device comprising: a heat source configured to generate an amount of heat; a heat member configured to be heated in accordance with the amount of heat generated by the heat source; and a back-up member providing a nip region for nipping the recording sheet in cooperation with the heat member; a temperature sensor configured to detect a temperature of the heat member; and a controller electrically connected to the heat source and the temperature sensor and configured to control the heat source by functioning as: an output determination unit configured to determine an output at which the heat source is operated to generate a target temperature, the output being determined by performing a calculation based on a difference between the target temperature and the temperature of the heat member detected by the temperature sensor, the target temperature being a temperature at which the heat member is to be heated; a first setting unit configured to set a first target temperature upon receipt of a print command; a second setting unit configured to set a second target temperature lower than the first target temperature; a switching unit configured to switch the target temperature from the first target temperature to the second target temperature when a prescribed condition is met; a determination unit configured to determine whether the recording sheet is being conveyed toward the nip region; a supplemental output control unit configured to generate a supplemental output, greater than the output obtained from the calculation, for performing supplemental heating of the heat member at least until the recording sheet reaches the nip region if the recording sheet is determined to be conveyed toward the nip region when the target temperature is switched from the first target temperature to the second target temperature; and an output reducing unit configured to gradually reduce the supplemental output back to the output obtained from the calculation when at least a second period of time has elapsed since the supplemental heating is initiated, the second period of time spanning from a time when the target temperature is switched from the first target temperature to the second target temperature to a time when the recording sheet has passed the nip region.