Patent ID: 7184697
Filing Date: 2007-02-27
Classification: G03G

Abstract:
1. A fixing apparatus comprising: a heating member having a conductive metal layer; a pressing member to supply a pressure to the heating member; an induction heater which includes a first coil placed outside the heating member, and a second coil which is placed outside the heating member and has an inductance different from the first coil, and heats the conductive metal layer of the heating member by induction heating; and an induction heating control circuit which includes a first self-excited inverter circuit to flow a high-frequency current variable in a first frequency range in the first coil, and a second self-excited inverter circuit to flow a high-frequency current variable in a second frequency range in the second coil, and controls the first and second self-excited inverter circuits to flow a high-frequency current simultaneously in the first and second coils and to vary the frequency of the high-frequency current in the first and second coils in the first and second frequency ranges, respectively, so as to control a temperature of the conductive metal layer; wherein the first frequency range is smaller than the second frequency range, and the difference between the maximum value of the first frequency range and the minimum value of the second frequency range is out of an audible frequency range.