To reduce stress on a sheet medium during fixing of an unfixed toner image onto the sheet medium to suppress deformation of the sheet medium, and to make the distribution of pressure on a fixing nip uniform to stabilize image fixation.
A fixing rubber roll has a rubber layer 52 on the peripheral face of a rigid core roll 51 having the shape of a pipe. The rigid core roll 51 has the shape of an inverted crown in which the outer diameter thereof continuously changes such that the outer diameter R2 of the longitudinal middle portion is the smallest and the outer diameters R1 of both ends are the largest, and has the shape of an inverted crown in the inner diameter thereof continuously changes such that the inner diameter r2 of the longitudinal middle portion is the smallest and the inner diameters r1 of both ends are the largest and, in addition, the thickness T2 of the longitudinal middle part is the largest.
Ryukichi Abe
Hirukawa Masanobu
Norihiko Uchida
Hideo Sugai
Kenji Aoki
Hiroshi Nagisawa
Akira Yonezawa
Tsutomu Iitaka