Patent ID: 7275481

Claim:
A printer comprising: a plurality of print drums located at a preselected interval in a sheet feed direction in which a sheet is conveyed; a drive pulley configured to rotate one of said plurality of print drums positioned at an upstream side in the sheet feed direction; a driven pulley configured to rotate another print drum positioned at a downstream side in the sheet feed direction; a timing belt passed over said drive pulley and said driven pulley to cause said print drum at the upstream side and said print drum at the downstream side to rotate in synchronism with each other; an adjustment pulley pair held in mesh with said timing belt; and steer pulley pairs respectively positioned between said drive pulley and said adjustment pulley pair and between said driven pulley and said adjustment pulley pair and held in contact with a rear surface of said timing belt for steering said timing belt, wherein said timing belt is ground such that a distance between tips of teeth of said timing belt and said rear surface is maintained constant with a variation of less than 0.1 mm over an entire length of said timing belt, and said adjustment pulley pair is movable to vary synchronism between said print drum at the upstream side and said print drum at the downstream side, wherein a turning period of said timing belt is an integral multiple of both of a rotation period of said drive pulley and a rotation period of said driven pulley.