Patent ID: 6959158

Claim:
A fixing device comprising: magnetic field generating means for generating a magnetic field; a heat generating member for generating heat by said magnetic field, wherein an image on a recording material is fixed by the heat from said heat generating member; electric power supply means for electric power supply to said magnetic field generating means; electric power changing means for changing electric power to said magnetic field generating means; a temperature detecting member for detecting a temperature of said heat generating member; electric power shut-off means for determining whether to shut off electric power supply to said magnetic field generating means on the basis of a comparison of a detected temperature provided by said temperature detecting member with a reference temperature during a period from start of heating to reaching a predetermined temperature and for shutting off the electric power supply in accordance with the determination, the reference temperature being determined on the basis of a heating period of said heat generating member and the electric power supply by said electric power supply means; and reference temperature changing means for changing, when said electric power changing means changes the electric power supply, the reference temperature on the basis of the electric power supply which has been changed.