Heater, fixing unit and image forming apparatus operable with a main and auxiliary power supply unit

摘要

A heater operable with main and auxiliary power supply units. A controller selects a first mode to permit discharge of the auxiliary power supply unit when a voltage or power from the auxiliary power supply unit is a startable value or greater without making reference to judgment information, or a second mode to permit discharge of the auxiliary power supply unit based on the judgment information when the voltage or power from the auxiliary supply unit is less than the startable value.