Apparatus and method for sheet feeding and separating using retard roll

Abstract

A sheet feeding and separating apparatus for feeding sheets from a stack by exerting a drive force against the top sheet. The sheet is urged off the stack by a nudger roll toward a retard nip formed where a feed roll contacts a retard roll. The retard roll is movable relative to the feed roll, and thus is capable of producing drive forces of varying magnitude at the retard nip to propel a sheet toward the copying mechanism. A controller signals the nudger roll to urge a sheet off the stack and then monitors a sensor to determine whether the sheet passes through the retard nip. A misfeed condition occurs when the sensor fails to detect a sheet within a predetermined length of time. In response, the controller moves the retard roll toward the feed roll to increase the drive force exerted on the sheet. The retard roll is further adapted to detect the occurrence of a multifeed when multiple sheets contact the retard nip. In response, the controller moves the retard roll away from, but remaining in contact with, the feed roll to decrease the drive force exerted on the sheet, thereby permitting individual sheets to pass through freely.