Patent ID: 7474871

Claim:
A fixing device comprising a pair of side walls, coupling means extending between the side walls, a thermally fixing roller rotatably supported between the side walls on the inside of the coupling means, pressing rotary means pressed onto the thermally fixing roller, and a separation member for separating paper from the outer peripheral surface of the thermally fixing roller; wherein positioning means are arranged at both end regions of the thermally fixing roller, the positioning means having circular outer peripheral surfaces concentric with the thermally fixing roller; the coupling means extends straight between the side walls, and includes a side frame having a flat outer surface; the separation member includes a strip-like flat support plate extending straight in the lengthwise direction maintaining a predetermined width, a first tilted flat plate bent from one side of the flat support plate in the direction of width and extending straight by a predetermined length, and a second tilted flat plate bent to the opposite side from the end of the first tilted flat plate and extending straight, which are made of a piece of elastic metal plate, wherein both end regions of the second tilted flat plate in the lengthwise direction form positioning protuberances extending by the same length, and an intermediate region between the two end regions forms a separation portion extending by a predetermined length which is shorter than the positioning protuberances; and the flat support plate of the separation member is fixed to the side frame by fixing means at a plurality of fixing portions provided on the flat support plate and on the side frame, which are brought in match with each other in a state where the flat support plate is overlapped on the outer surface of the side frame of the coupling means, and ends of the positioning protuberances are brought into contact with the outer peripheral surfaces of the corresponding positioning means in a state where the separation member is fixed to the side frame, so that the end of the separation portion is positioned maintaining a predetermined gap with respect to the outer peripheral surface of the thermally fixing roller.