Patent ID: 9261834
Filing Date: 2016-02-16
CPC Classification: G03G

Claim Text:
1. A fixing device for fixing an image on a recording material by heating the image while feeding, through a nip, the recording material on which the image is formed, said fixing device comprising: a cylindrical rotatable member having an electroconductive layer; a magnetic member inserted into a hollow portion of said rotatable member; wherein said magnetic member does not form a loop outside the electroconductive layer; a coil helically wound outside said magnetic member at the hollow portion, wherein said coil forms an AC magnetic field by a flow of a current therethrough to cause the electroconductive layer to generate heat through electromagnetic induction heating; and a back-up member for forming the nip together with said rotatable member, wherein when a circumferential direction resistance R of the electroconductive layer is represented by the following formula (1), a frequency f of the AC magnetic field and the circumferential direction resistance R satisfy the following formula (2): where ρ is a volume resistivity of the electroconductive layer at a fixing temperature, t is a thickness of the electroconductive layer, r is a radius of the electroconductive layer, and w is a length of the electroconductive layer with respect to a generatrix direction of said rotatable member.