More accurately correcting sheet position and skew in a desired print
media sheet trajectory in a printer paper path, with a registration
system including sheet drive nips defined by laterally spaced and
differentially driven elastomer surfaced frictional sheet drive rollers
and mating undriven idler rollers have a non-slip rotational sheet
engagement. The undriven idler rollers have rotary encoders producing
encoder signals corresponding to their rotation by a sheet in the nip,
which encoder signals are provided to a controller for the registration
system to control forward and differential drive motor systems for the
sheet drive rollers so as to substantially correct for errors in the
desired trajectory of said sheet by sheet drag forces acting on the
elastomer surfaced sheet drive rollers in the sheet drive nips.