Patent ID: 8583020

Claim:
A fixing device comprising: a stationary tubular belt holder extending in an axial direction thereof; a rotatable, flexible fuser belt looped into a generally cylindrical configuration around the belt holder extending in the axial direction of the belt holder, the tubular belt holder retaining the fuser belt in shape as the belt rotates in a circumferential direction of the belt holder; a contact member extending in the axial direction of the belt holder, accommodated in the belt holder inside the loop of the fuser belt; a rotatable pressure member extending in the axial direction, disposed opposite the belt holder with the fuser belt interposed between the contact member and the pressure member to rotate the fuser belt, the pressure member pressing against the contact member through the fuser belt to form a fixing nip through which a recording medium on the fuser belt is conveyed in a conveyance direction under heat and pressure; and a heater disposed adjacent to the belt holder to heat directly or indirectly a predetermined circumferential portion of the fuser belt upstream from the fixing nip in the circumferential direction, the belt holder including: a first circumferential section having a surface facing the heated portion of the fuser belt, defining part of an imaginary, substantially perfect cylindrical surface whose curvature is substantially constant; and a second circumferential section upstream from the heated portion of the fuser belt in the circumferential direction, which extends radially outward from the imaginary cylindrical surface.