Image forming apparatus, roller, belt, and fixing unit of image forming apparatus

摘要

A tubular roller to support a belt having an inner surface provided with a protruding circumferential edge having a width includes a first portion, a second portion, and a third portion. The first portion has a first outer radius and contacts the inner surface of the belt. The second portion has a second outer radius smaller than the first outer radius of the first portion. The third portion is connected to the first portion with a first vertically extending wall and to the second portion with a second vertically extending wall and has a third outer radius smaller than the second outer radius.