Fixing device including an electromagnetic inductive coil member providing inductive heating

A fixing device comprising an endless heating member which is adapted to be contacted with a fixable member to thereby enable an image on the fixable member to be thermally fixed;

• an electromagnetic inductive coil member disposed close to the endless heating member and inductively heating the endless heating member;
• and an inverter driving circuit supplying an AC current to the electromagnetic inductive coil member;
• wherein said coil member is constructed such that in a state where said coil member is positioned in the fixing device, an inductance L of said coil member and a load resistance R of said coil member meet a formula of:
• V2/[(2πfL)2+R2]−½>600 under conditions where a supply voltage of the inverter driving circuit is in the range of 100 to 250V, and a frequency thereof is in the range of 20 to 50 kHz.