A system is described for providing positional information regarding a media sheet in an image forming apparatus. The system includes a laser for providing a beam of collimated light and a mechanism for moving a media sheet along an imprinting path. Beam sensors are placed in the imprinting path, and...http://www.google.es/patents/US5252991?utm_source=gb-gplus-sharePatente US5252991 - Media edge sensor utilizing a laser beam scanner
