Patent ID: 7558508

Claim:
An image forming apparatus comprising: a plurality of rollers; and an endless belt wound around said rollers, said rollers including: a driving roller which drives said belt wound around said rollers and a driven roller set which is driven by said driving roller via the movement of the endless belt, said driven rollers having one or more metal rollers, and wherein at least one of said metal rollers is a smooth roller which satisfies following conditions (i) and (ii); (i) a surface roughness Rz≦2 μm; and (ii) an arithmetic inclination average Δa≦0.06; where said Δa is obtained from an equation (1) below: Δ ⁢ ⁢ a = 1 L ⁢ ∫ 0 L ⁢  ⅆ ⅆ x ⁢ f ⁡ ( x )  ⁢ ⅆ x ( 1 ) where L=a reference length taken from a roughness curve; and f (x)=a height of the roughness curve at a position x within said reference length L along a lengthwise direction of the roller.