Patent ID: 6816688
Filing Date: 2004-11-09
Classification: G03G,H05B

Abstract:
An image forming apparatus comprising:a pressing roller for pressing a sheet at the time of a fixing operation; a fixing roller having a hollow portion, facing said pressing roller, rising in temperature by being heated, and fixing a developer to the sheet by sandwiching the sheet between said fixing roller and said pressing roller; induction heating coils including a center-section coil and an end-section coil, and arranged inside said fixing roller in an axial direction so as to leave a space between the center-section coil and the end-section coil, the space being adjusted so that the temperature of one surface of said fixing roller, said one surface opposing the space, is not higher than the temperatures of the other surface of said fixing roller, said other surface opposing central portions of the coils; and overheating prevention devices for monitoring an abnormally overheated condition of said fixing roller, and for breaking a circuit with said fixing roller so as to turn-off power applied to the two coils at the time of the occurrence of the abnormally overheated condition in which the temperature of the one surface of said fixing roller is more than a predetermined temperature, said overheating prevention devices being provided so as to oppose the center-section coil and the end-section coil, but not to oppose the space between the center- and end-section coils.