Induction heating apparatus, heat fixing apparatus and image forming apparatus

A heat fixing apparatus for conveying under a pressure a sheet bearing an unfixed toner image thereon and for heat fixing said unfixed toner image to said sheet, comprising:

• a rectifying circuit for rectifying a commercial power supply;
• an inverter power source circuit including an excitation coil receiving a high frequency current for induction heating a heat generating member, and a switching element for supplying said excitation coil with the high frequency current utilizing the output of said rectifying circuit;
• and
• power control means which controls a switching timing of said switching element, in order to control an output of said inverter power source circuit;
• wherein said power control means includes maximum output setting means which controls said switching timing, in such a manner that the maximum output of said inverter power source circuit is set according to a voltage of the commercial power supply.

An image forming apparatus comprising:

• a heat fixing apparatus which conveys under a pressure a sheet bearing an unfixed toner image thereon for heat fixing said unfixed toner image to said sheet, and
• control means which controls operations of units for executing an image forming operation, wherein said heat fixing means includes:
• a rectifying circuit for rectifying a commercial power supply;
• an inverter power source circuit including an excitation coil receiving a high frequency current for induction heating a heat generating member, and a switching element for supplying said excitation coil with the high frequency current utilizing the output of said rectifying circuit;
• and
• power control means which controls a switching timing of said switching element, in order to control an output of said inverter power source circuit;
• wherein said power control means includes maximum output setting means which controls said switching timing, in such a manner that the maximum output of said inverter power source circuit is set according to a voltage of the commercial power supply.