Patent ID: 7129448

Claim:
A heating apparatus for an electromagnetic induction heating system, comprising: a heat roller that comprises magnetic and conductive material; and a magnetic excitation coil configured to be positioned around an outermost portion of an external periphery of the heat roller, the magnetic excitation coil being configured to generate a magnetic field that extends to the heat roller, to generate an eddy current within the heat roller, and to generate Joule heat within the heat roller, the magnetic excitation coil being further configured to generate a smaller magnetic field at the center area of the heat roller than at the side areas of the heat roller, wherein a thickness of the magnetic excitation coil, measured within an angle of between about 30°–60° with respect to a lower edge of the magnetic excitation coil at the side areas of the heat roller is greater than a thickness of the magnetic excitation coil measured within an angle of between about 30°–60° with respect to a lower edge of the magnetic excitation coil at the center area of the heat roller.