IMAGE HEATING DEVICE AND IMAGE FORMING APPARATUS PROVIDED WITH THE SAME

摘要

PROBLEM TO BE SOLVED: To evade inconvenience that warming up time becomes long by setting Curie temperature in the vicinity of fixing temperature when excessive temperature rise in a region outside paper width is suppressed by the Curie temperature that magnetic shunt material constituting a heating element. SOLUTION: Magnetic flux detour member 51 composed of the magnetic shunt material and magnetic shielding material 52 composed of an electric conductor are disposed inside a heating roller 22 composed of the magnetic shunt material. The Curie temperature of the magnetic flux detour member is set higher than predicted temperature of the magnetic flux detour member at the point of termination of the warming up and lower than the predicted temperature of the magnetic flux detour member at the point when the region outside the paper width reaches abnormal temperature when recording paper which is narrow in width is passed through continuously. A new magnetic path is formed through which the magnetic flux detour member is passed by having the magnetic flux detour member retaining magnetism until reaching the fixing temperature in warming up. Then, the magnetic path is shut off by the magnetic shielding member by having the magnetic flux detour member losing most of its magnetism before the region outside the paper width reaches the abnormal temperature when the recording paper of the narrow width is continuously passed through. COPYRIGHT: (C)2008,JPO&INPIT