Patent ID: 7186959

Claim:
A fixing device comprising: a heating member comprising a conductive member, in which an active surface of the conductive member is movable in a predetermined direction; a press member that is configured to press a toner on a medium that passes between the heating member and the press member; a first coil that is provided close to a first position of the heating member, which first coil constitutes a first resonant circuit; a second coil that is provided close to a second position of the heating member, which second coil constitutes a second resonant circuit that is connected in parallel with the first resonant circuit; a switching circuit that is configured to supply power to the first and second resonant circuits; a driving circuit that is configured to instruct the switching circuit to drive at a predetermined driving frequency; a CPU that is configured to control at least the driving circuit; a first temperature detector that is configured to output the temperature at the first position; a second temperature detector that is configured to output the temperature at the second position; and an active surface movement controlling device that is configured to control at least the movement of the active surface of the conductive member, wherein a second resonance frequency f 2 of the second resonant circuit is different from a first resonance frequency f 1 of the first resonant circuit, wherein the driving circuit is configured to drive the switching circuit at the first resonance frequency f 1 and second resonance frequency f 2 , and wherein the driving circuit is configured to drive the switching circuit at a third resonance frequency f 3 , which is between the first resonance frequency f 1 and second resonance frequency f 2.