Method and apparatus for paper control and skew correction in a printer

摘要

A method for correcting the skew between the leading edge of a sheet of paper and the nip of a roller assembly in a printing mechanism includes the steps of advancing a sheet of paper into the nip and slightly therebeyond. The rollers are then rotated in reverse, causing the paper to retract from the roller assembly, with the angle and weight of the paper maintaining the leading edge within the nip. As the rollers continue to rotate backwards, the paper jiggles or dances allowing the leading edge to settle parallel with the nip under its own weight. The paper is then readvanced through the roller assembly with its leading edge parallel to the nip. A mechanism applies a drag force to the paper when the paper is being retracted from the roller assembly to keep the leading edge of the paper in the nip.PPA single motor control apparatus includes a processor-controlled drive motor, a drive roller assembly, a pick roller assembly and a gearing arrangement coupling the drive motor to the roller assemblies, for selective control of the timing, speed and rotational direction thereof to achieve the above described method.