Fixing device with multiple heaters, image forming apparatus, and image forming method

A fixing device comprising:

• a fixing rotator having an endless form;
• a temperature detector to detect a temperature of the fixing rotator;
• a pressure rotator in contact with an outer circumferential surface of the fixing rotator;
• a nip formation pad disposed inside a loop of the fixing rotator to form a nip between the fixing rotator and the pressure rotator;
• and
• a plurality of heaters to heat an inner circumferential surface of the fixing rotator, the plurality of heaters including:
• a first heater to uniformly generate heat in a longitudinal direction of the fixing rotator and independently receive power;
• a second heater to generate different heat amounts at different positions in the longitudinal direction of the fixing rotator and receive power together with the first heater, the second heater generating larger heat amounts in each of end portions of the second heater than a center portion of the second heater;
• and
• a reflector between the nip formation pad and the plurality of heaters,
• wherein an amount of heat generated at a center portion of the second heater is smaller than an amount of heat generated at a center portion of the first heater,
• the fixing rotator has a thickness equal to or smaller than 0.2 mm,
• the reflector reflects the heat generated by the plurality of heaters to heat the inner circumferential surface of the fixing rotator at a place other than the nip,
• the fixing device includes only one temperature detector and one abnormal temperature detector, the one temperature detector faces directly the center portion of the second heater, and the one abnormal temperature detector is disposed at a position facing one of the end portions of the second heater at which the plurality of heaters generate a total heat generation amount larger than at another position, and
• total heat amount generated by both end portions of the first heater and the both end portions of the second heater is larger than total heat amount generated by the center portion of the first heater and the center portion of the second heater by 5% to 15% in a total heat amount ratio under a rated voltage.