Fusing device and method

Claim 1

In an electrophotographic apparatus, a fusing device for fixing a resinous powder image to a substrate, a pair of first and second rotatable members, through which said substrate carrying the powder image passes and comes into contact with said first member, said first member having a high temperature resistant, elastic, compressible coating surrounding and in physical contact with a heat conducting support member, said second member beIng elastic and deformable by said first member when in pressure contact, the outer surfaces of both of said members being free of an offset preventing liquid, heating means disposed within said support member for heating the outer surface of said elastic coating to an elevated temperature, the thickness of said elastic coating being such that heat from said heating source is readily conducted through said coating and is at least about 3 mils, pressure means for applying a meshing force between said members at a pressure sufficiently high to cause said coating to be in a compressed state about said powder image and to deform said second member so as to create a contact zone, but sufficiently low to avoid detrimental effects to said substrate, and means for rotating said members at a speed such that the powder image is in contact with said coating for a sufficient time to transfer sufficient heat to the powder image so as to raise the resinous powder to a temperature capable of fusing said powder image to said substrate above a predetermined minimum fuse quality without offsetting to said coating.