FIXING DEVICE AND IMAGE FORMING APPARATUS

PROBLEM TO BE SOLVED: To make it possible to avoid shortening of the lives of a nip forming rotating member and a curvature increasing member.SOLUTION: A fixing device 40 fixes an image to a recording medium at a fixing nip formed by sandwiching a heated rotatable endless fixing belt 43 into pressure contact with a pressure member, such as a pressure roller 45 and a nip forming rotating member, such as a fixing roller 41, and increases the curvature of the fixing belt by bringing a curvature increasing member 48 into contact with an inner peripheral surface of the fixing belt after passing through the fixing nip. The curvature increasing member can move in the radial direction with respect to an outer peripheral surface of the nip forming rotating member.SELECTED DRAWING: Figure 4 【課題】ニップ形成回転部材及び曲率増大部材の寿命が短くなるのを抑制することができる。【解決手段】加熱された回転可能な無端状の定着ベルト４３を加圧ローラ４５等の加圧部材と定着ローラ４１等のニップ形成回転部材とで挟んで圧接して形成した定着ニップで画像を記録媒体に定着させ、曲率増大部材４８を定着ニップ通過後の定着ベルトの内周面に当接して定着ベルトの曲率を大きくした定着装置４０において、曲率増大部材は、ニップ形成回転部材の外周面に対し径方向に移動可能に構成されている。【選択図】図４