Patent ID: 7027749

Claim:
A fixing device comprising: a substantially cylindrical heat roller which is used to fix toner on a paper sheet; a center heater which is provided inside the heat roller, spaced from a central axis of the heat roller in a first radial direction, and located in a center region in a longitudinal direction of the heat roller; side heaters which are placed, inside the heat roller, spaced from a central axis of the heat roller in a second radial direction, and located in side regions in the longitudinal direction of the heat roller; a first power shutoff unit which is installed in a position corresponding to the center heater in the longitudinal direction of the heat roller, on a heat roller surface where distances to the center heater and side heater are equal in the diameter direction of the heat roller, and which shuts off power supply to the center heater and side heaters when a surface temperature of the heat roller in the installation position has reached a predetermined operating temperature; and a second power shutoff unit which is installed in a position corresponding to one of the side heaters in the longitudinal direction of the heat roller, on a heat roller surface where distances to the center heater and side heater are equal in the diameter direction of the heat roller, and which shuts off power supply to the center heater and side heaters when a surface temperature of the heat roller in the installation position has reached the same operating temperature as the first power shutoff unit.