| 摘要 |
PROBLEM TO BE SOLVED: To maintain a temperature difference between a paper passing region of a heating rotating body and a non-paper passing region of the same at an appropriate temperature difference in a fixing device which performs heat fixing operation by using the heating rotating body comprising a resistance heating body as a heat source and to prevent increase in power consumption rate in the non-paper passing region during operation.SOLUTION: A fixing device performs heat fixing of a recording sheet by passing it through a heating rotating body while pressing it against the heating rotating body which comprises as its heat source a resistance heating body having an electric resistivity changing with temperature. The fixing device comprises: monitoring means 54, 55 which monitor temperatures of a paper passing region and a non-paper passing region of the heating rotating body; supply means 500 which supplies power to the resistance heating body during heat fixing operation in such a manner that the temperature of the paper passing region is maintained at a target temperature; cooling means 80 which cools the non-paper passing region; and control means 50 which controls the cooling of the non-paper passing region depending on the temperature of the non-paper passing region during the heat fixing operation in such a manner that the electric resistivity of the part of the resistance heating body corresponding to the non-paper passing region is smaller than that of the part corresponding to the paper passing region and the absolute value of the temperature difference between the two regions does not exceed an allowable temperature difference. |
