Heating control apparatus

摘要

A heating control device of an image forming apparatus determines a phase of heat control in accordance with a target temperature and a current temperature of a fixing roller and a change status of the current temperature, determines a control unit period tp, a main heater turn-on time tm, a sub-heater turn-on time ts and Duty No. in accordance with a count of a counter which counts the number of control units which are unit periods of control and a shift status of phase, and finally determines a type of control and supplies powers to the main heater and the sub-heater. A proper heater power to control to a target temperature can be applied in a short period and a temperature ripple is reduced.