Patent ID: 7046937

Claim:
A fixing device of an image forming apparatus comprising a heating roller according to a system in which a plurality of heating sources different in light-distribution characteristics are disposed internally, and the surface is divided in regions in the lengthwise direction, wherein: as said plurality of heating sources, there are provided at least, a heating source for mainly heating a heating roller surface in a first region through which paper of small width passes, and a heating source for mainly heating a heating roller surface in a second region through which paper of small width does not pass where paper of large width is carried; there are provided at least, a temperature detector for detecting a temperature of a heating roller surface in a region through which paper of small width passes, and a temperature detector for detecting a temperature of a heating roller surface in a region through which paper of small width does not pass where paper of large width is carried; and as warming up operation is continued, temperatures of heating roller surfaces in both the first and the second regions are detected, and when a temperature detected by the temperature detector for detecting a temperature of a heating roller surface in either the first or the second region reaches a temperature capable of fixing, a ready display is lighted.