Fixing device of image forming apparatus employing electro-photographic process and controlling method of the same

A control method of a fixing device in an image forming apparatus constituted by 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 region in the lengthwise direction, the method comprising:

• detecting at least, a temperature of a heating roller surface in a region through which paper of small width passes, and 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
• continuing warming up operation, and when a temperature of a heating roller surface in said either region reaches a temperature capable of fixing, a ready display is lighted.

A control method of a fixing device in an image forming apparatus constituted by 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 region in the lengthwise direction, the method comprising:

• detecting at least, a temperature of a heating roller surface in a region through which paper of small width passes, and 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
• continuing warming up operation, and when a temperature of a heating roller surface in said either region reaches a temperature capable of fixing, a ready display is lighted, thereafter a heating roller surface in a region not having reached a temperature capable of fixing is heated by forcibly lighting a heating source till the fixed conditions are satisfied, and at the time of the forcible lighting operation, a heating roller surface in a region having reached a temperature capable of fixing is not heated.