Patent ID: 8639171

Claim:
A fixing device for thermally fixing an unfixed image formed on a recording sheet by passing the recording sheet through a fixing nip, the fixing device comprising: a heat-generating endless belt that rotatably runs about a rotation axis; a first pressure member disposed inside a running path of the heat-generating endless belt; and a second pressure member disposed to press the endless belt against the first pressure member from outside the running path to form the fixing nip, wherein the heat-generating endless belt includes: a resistive heat layer that generates heat upon having electric current applied thereto; and a pair of electrode layers that receive electric current, each electrode disposed along a different one of widthwise edges of the heat-generating endless belt, the resistive heat layer has (i) reduced thickness portions each along a widthwise edge thereof and (ii) a middle portion between the reduced thickness portions, each reduced thickness portion being thinner than the middle portion and connected to the middle portion with a wall surface upright in a direction perpendicular to the rotation axis of the heat-generating endless belt to define a stair shape, and each electrode layer is disposed on the resistive heat layer to be in contact with a corresponding one of the wall surfaces, wherein the first pressure member is a cylindrical pressure roller, the heat-generating endless belt is fit with clearance about the first pressure member, and the first pressure member and the heat-generating endless belt rotate following rotation of the second pressure member.