Patent ID: 8824942

Claim:
A fixing device comprising: a rotating member that has a shape of a cylinder and rotates in a circumferential direction of the cylinder, the rotating member having a slot at an end of the cylinder and a protruding section extending along an edge of the slot at a front side in a rotational direction of the rotating member, the rotating member receiving a rotational driving force via the slot, the slot extending through the cylinder from an inside to an outside thereof and also extending from the end toward a center of the cylinder, the protruding section protruding in a direction that intersects a peripheral wall of the cylinder; a pressing member that presses a recording medium bearing an unfixed toner image on a surface thereof by nipping the recording medium together with the rotating member so as to fix the toner image onto the surface; a heat source that heats the recording medium nipped between the rotating member and the pressing member; and a driving member having an engagement section that is engaged with the slot in the rotating member and is in contact with the protruding section at a position separated from the peripheral wall of the cylinder by a certain distance, the driving member having a gap between the driving member and the rotating member, a portion of the gap is defined by an inner surface of the driving member that is radially outward from the peripheral wall of the cylinder and another portion of the gap is formed between the engagement portion of the driving member and an upper part of the protruding section wherein the inner surface of the driving member deviates from a cylindrical profile around the engagement portion, the driving member imparting the rotational driving force to the rotating member via the engagement section.