Patent ID: 7243917

Claim:
An improved sheet registration system for a moving sheets path for accurately correcting a sheet position relative to a desired sheet trajectory, said sheet registration system including a control system and at least one frictional sheet drive roller with a drive system and a mating undriven idler roller forming at least one sheet trajectory controlling sheet drive nip between said at least one frictional sheet drive roller and said mating undriven idler roller, wherein said mating undriven idler roller has non-slip rotational engagement with said sheet in said at least one sheet drive nip to rotate in correspondence with said sheet trajectory, and wherein said mating undriven idler roller has a rotary encoder operatively connected thereto to produce encoder electrical signals corresponding to said rotation of said mating undriven idler roller, which encoder electrical signals are provided to said control system to control said drive system driving said at least one frictional sheet drive roller, wherein said at least one frictional sheet drive roller comprises a transversely spaced pair of such drive rollers with a differential drive system providing differential sheet drive nips, and said differential drive system is controlled by said control system to impart sheet trajectory controlling skew corrective motion including partial rotation of a sheet in said differential sheet drive nips.