| 摘要 |
PROBLEM TO BE SOLVED: To prevent the irregularity of a toner image caused by the expansion of air and the generation of steam inside a belt nip press-contacted with a heating fixing roll in an image fixing device fixing unfixed toner on a recording sheet by heating and pressing. SOLUTION: A pressure imparting member 11 abuts on the side of the inside surface of an endless belt 15, and the endless belt is pressed along the surface of the heating fixing roll 1 by a press-contact surface. Pressure acting on the press-contact surface is set to be higher than the pressure suppressing and stopping volume expansion caused by the temperature rising of gas taken in between the heating fixing roll 1 and the endless belt 15; and especially between the pressure Pn at the inside of a nip by the endless belt, the temperature Tn of the heating fixing roll, atomospheric pressure Po and ambient temperature To, it is desirable to set them so that the relation of Pn>=Po×(Tn/To-1) may hold. Thus, the occurrence of a gap caused by the thermal expansion of the air or the like at the inside of the nip is prevented. |
