Patent ID: 7641192

Claim:
A sheet feeder comprising: a pair of feed rollers operable to have a plurality of successive rotational motions, so as to be rotated by a predetermined amount in each one of the successive rotational motions, for thereby causing a sheet nipped between said pair of feed rollers, to be fed along a feed path by a desired distance as a result of said each one of the successive rotational motions; a back-tension applier disposed in the feed path, and configured to apply a back tension to the sheet that is fed along the feed path; a rotary encoder disposed on one of the pair of feed rollers; a sheet position sensor disposed in the feed path; and a motion controller configured to estimate an amount of slipping of the feed rollers relative to the sheet, to control the successive rotational motions of said feed rollers, and to command said feed rollers to be rotated by a compensated amount that includes a supplementary amount in addition to said predetermined amount, in each of at least one of the successive rotational motions, wherein said supplementary amount included in said compensated amount is an amount that is predetermined based on the estimated amount of slipping of said feed rollers relative to the sheet to which the back tension is applied.