Patent ID: 9104149
Filing Date: 2015-08-11
Classification: G03G

Abstract:
1. A fixing device comprising: a belt having an inner circumferential surface and comprising: a secured member comprising a contact portion and is secured such that the secured member is in contact with the inner circumferential surface of the belt; a support roller configured to rotatably support the belt; a heating unit configured to heat the belt; and a pressure roller comprising an elastic surface layer that is elastically deformed when the elastic surface layer presses the belt against the secured member so as to form a fixing portion, a recording medium that holds an unfixed image formed thereon passing through the fixing portion, the pressure roller being driven to rotate; wherein the contact portion of the secured member comprises an insertion portion provided at an insertion end and a nip contact portion having an arc-shaped first curved surface including a first radius of curvature corresponding to the pressure roller, and the nip contact portion is in contact with the belt and in contact with the pressure roller with the belt nipped therebetween when the fixing portion is formed, wherein the recording medium is inserted into the fixing portion from an insertion end side, and the insertion portion comprising a second radius of curvature curving opposite to the first radius of curvature, wherein conditions t(1/r wherein the pressure roller has a reverse crown shape, diameters of opposite end portions of the pressure roller are larger than a diameter of a central portion of the pressure roller.