Heating roller, heating belt, image heating device, and image forming device

Abstract

A heating roller () includes a heat generating layer () that generates heat by electromagnetic induction, a heat insulating layer (), and a supporting layer (), which are provided inwardly in this order. The heat generating layer () is composed of at least two layers that are a first heat generating layer of a magnetic material and a second heat generating layer of a non-magnetic material. The first heat generating layer has a specific resistance higher than a specific resistance of the second heat generating layer and a thickness larger than a thickness of the second heat generating layer. This allows the second heat generating layer to function effectively as a heat generating part that generates heat by electromagnetic induction. Thus, compared with the case where the heat generating layer () is formed only of a single layer of a magnetic material, heat generation efficiency is increased, thereby allowing warm-up time to be reduced. Further, the heat generating layer () is heated intensively, so that heat generation of the supporting layer () is reduced, thereby allowing the prevention of breakage of, for example, bearings supporting the heating roller ().