TRAIL EDGE DOCUMENT REGISTRATION
Original Publication Date: 1982-Feb-28
Included in the Prior Art Database: 2004-Apr-03
Xerox Disclosure Journal
In an electrophotographic printing machine, it is necessary to precisely register the original document being reproduced on the imaging platen. Frequently, recircu-lating document handling systems are employed for moving the original document from a stack onto the platen. The recirculating document handling system employs belts having apertures or holes therein in communication with a vacuum plenum for producing a suitable vacuum to secure the original document thereto during the advancement thereof onto the platen. Hereinbefore, the lead edge of the original document has frequently been registered. However, the holes within the belt must be within the smallest document size to prevent their being reproduced on the copy sheet. In lieu of lead edge registration, rear edge registration may be employed. The holes in the vacuum plenum are located only in the region of the registration edge. In operation, the lead edge of the copy sheet is secured to the belt with the holes in the vacuum plenum being located near the rear registration edge. As the original document passes thereover and is positioned on the platen, the trail edge passes the fixed registration edge. Belt motion is then reversed for a short dis-tance while the registration edge causes the original document to slide relative to the vacuum belt. Since the vacuum holes in the plenum are located in the region adjacent their rear edge, the document holding force is maximized as the lead edge enters the platen region with the desired pressure distribution being generated on the document for the slip registration action. In this way, the plenum holes are not reproduced and the document is suitably secured to the belt for advancement therewith to a pre-selected position on the imaging platen.