Patent ID: 7359663

Claim:
An image forming apparatus for forming a color image composed of a plurality of colors, comprising: a plurality of developing units for developing toner images of the respective colors; a transfer belt for superimposedly transferring the toner images of the respective colors developed by the developing units onto a surface of the transfer belt or onto a recording sheet transported over the surface of the transfer belt; a first roller for driving the transfer belt in a state that the transfer belt is wound around the first roller; and a second roller which is rotated along with the driving of the transfer belt driven by the first roller in a state that the transfer belt is wound around the second roller, wherein the image forming apparatus satisfies a relation defined by the equation (1.1) D 2= N·D 1 (1.1) where D1 is a belt-inclusive outer diameter of the first roller around which the transfer belt is wound, including a thickness of the transfer belt, D2 is an outer diameter of the second roller, and N=n or 1/n where n is a positive integer.