Patent ID: 8204397

Claim:
A fixing apparatus, comprising: a heating member comprising a heating roller which has a center part and a peripheral part; a fixing belt which is heated by the heating member; a control unit which controls the heating member so that the center part and the peripheral part alternately heat the fixing belt; a fixing roller; a pressing roller to press the fixing roller through the fixing belt; a first heater that is included in the heating roller and mainly heats the center part of the heating roller and; a second heater that is included in the heating roller and mainly heats the peripheral part of the heating roller, wherein, the control unit controls a temperature of the heating roller by an on/off control of the first heater and the second heater, the control unit performs the on/off control in which when one of the first heater and the second heater is turned on, the other is turned off, and the fixing belt is wound around the heating roller and the fixing roller and circulates around the heating roller and the fixing roller; a first sensor configured to mainly detect a temperature of the center part of the heating roller; and a second sensor configured to mainly detect a temperature of the peripheral part of the heating roller, wherein, (1) in a case where both the temperatures detected by the first and the second sensors are lower than a specified set temperature, the temperature control unit performs the on/off control which is repeated at a cycle of a sum of a first period and a second period shorter than the first period, and in this case, (a) in a case where the temperature detected by the first sensor is lower than the temperature detected by the second sensor, the first heater is turned on in the first period, and the second heater is turned on in the second period, (b) in a case where the temperature detected by the second sensor is lower than the temperature detected by the first sensor, the second heater is turned on in the first period, and the first heater is turned on in the second period, (2) in a case where the temperature detected by the first sensor is lower than the set temperature, and the temperature detected by the second sensor is equal to or higher than the set temperature, the first heater is turned on, and the second heater is turned off, (3) in a case where the temperature detected by the second sensor is lower than the set temperature, and the temperature detected by the first sensor is equal to or higher than the set temperature, the second heater is turned on, and the first heater is turned off, and (4) in a case where both the temperatures detected by the first and the second sensors are equal to or higher than the set temperature, both the first and the second heaters are turned off.