Patent ID: 7868272

Claim:
An induction heating device comprising: a heating roller having a plurality of conductive heat generating layers; and a magnetic field generator positioned adjacent an external periphery of the heating roller; wherein the heating roller is configured such that the conductive heat generating layers are capable of generating heat as a result of application of alternating magnetic fields, produced by the magnetic field generator, to the conductive heat generating layers of the heating roller; wherein one of said conductive heat generating layers of the heating roller comprises a conductive shaft that supports the heating roller, and another of said conductive heat generating layers comprises a surface heat generating layer; a non-conductive heat resistant support member positioned between the conductive shaft and the surface heat generating layer; wherein the heating roller is configured to promote heat generation by the conductive shaft; wherein the heating roller is configured to promote heat accumulation in the non-conductive heat resistant support member; wherein the heating roller is configured to accumulate in the non-conductive heat resistant support member heat generated by the conductive shaft and the surface heat generating layer; wherein the heating roller comprises the non-conductive heat resistant support member, the surface heat generating layer, an elastic layer, and a surface release layer positioned about the conductive shaft, and the non-conductive heat resistant support member and the elastic layer comprise material having a coefficient of linear expansion within a predetermined range, and the surface heat generating layer comprises a composite material comprising, as a base material, a material of the non-conductive heat resistant support member or the elastic layer that is within the predetermined range of coefficient of linear expansion and a conductive material that has been dispersed within the base material; wherein the surface heat generating layer positioned between the conductive shaft and the surface release layer has a structure in which a plurality of elastic layers and heat generating layers are formed alternately; and wherein the non-conductive heat resistant support member, the surface heat generating layer, the elastic layer, and the surface release layer are positioned in that order about the conductive shaft.