Eccentric idler for deskew of long sheets

摘要

A sheet aligning and registration device for a printing machine. In a stalled roll registration device there is provided a drive mechanism preceding the stalled rolls (125) which allows a sheet to move while within the drive nip. The drive mechanism uses a drive roll (121) and an eccentric idler roll (122) in contact therewith. The idler is biased against the drive roll by a compression spring (123) such that as the eccentric idler roll rotates, the spring is alternately compressed and relaxed. When a sheet is driven through the drive mechanism and into the stalled nip, a buckle (49) is formed which causes a force (132) to be exerted on the drive nip which causes the eccentric roll to stall in the horizontal position in which little normal force is exerted on the sheet. The sheet is then free to deskew and align in the stalled nip. Once the sheet is aligned and deskewed, the stalled nip is actuated and the sheet is forwarded to a process station. When the sheet clears the eccentric drive nip the friction of the elastomeric drive roll against the eccentric idler causes the idler to rotate and drive the next sheet. <IMAGE>