Heating roller, image heating apparatus, and image forming apparatus

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 supporting layer () is formed of a material having a specific resistance of 1×10Ωm or higher. Therefore, even when the heat generating layer () has a thickness smaller than a skin depth, i.e. a thickness defined by a flow of an induction current, so that magnetic flux penetrates the heat generating layer () and even reaches the supporting layer (), heat generation of the supporting layer () under an eddy current can be suppressed. Thus, the heat generating layer () can be decreased in thermal capacity, and heat generation of the supporting layer () is suppressed, so that only the heat generating layer () can be heated efficiently. As a result, a warm-up time can be reduced. Further, breakage by heat of, for example, bearings supporting the heating roller () can be prevented.