Patent ID: 6055390
Filing Date: 2000-04-25
Classification: G03G

Abstract:
A belt fixing device for an image forming apparatus, comprising:a fixing roller;a heating roller;an endless fixing belt spanned around the fixing roller and the heating roller;a pressing roller disposed opposing the fixing roller via the fixing belt;a heater disposed inside the heating roller for heating the fixing belt;a heating area where the fixing belt is heated by the heating roller;a fixing area including a first fixing part where the pressing roller contacts the fixing belt without pressing the fixing roller and a second fixing part where the pressing roller presses the fixing roller via the fixing belt;temperature detector means for detecting a surface temperature of the fixing belt in the heating area; andtemperature control means for controlling the surface temperature of the fixing belt in the heating area to one of a first prescribed temperature and a second prescribed temperature, based on a detected result of the temperature detector means, wherein the first prescribed temperature is higher than the second prescribed temperature, wherein the fixing area includes a fixing nip portion formed between the fixing roller and the pressing roller in the second fixing part, and wherein said temperature control means controls the surface temperature of the fixing belt in the heating area so that a temperature difference between the second prescribed temperature and a surface temperature of the fixing belt at an exit of the fixing nip portion when a fixing operation is started is less than about 20.degree. C.