Patent ID: 7232122

Claim:
A document assembly system with jam detection capability comprising an accumulation chassis comprised of a series of pusher fingers for pushing consecutive collations of documents in a downstream direction, the chassis having a chassis speed in the downstream direction; a document feeder positioned above the chassis, the document feeder controlled to release documents to the chassis to form the collations, the document feeder oriented so as to release documents in a diagonal flight path at a feeder speed, the flight path having components in the downward and downstream directions, the feeder speed being a function of chassis speed to coordinate the proper formation of collations; a set of horizontal photo-sensors below the document feeder at a level substantially at a top region of the pusher fingers to detect lead and tail edges of documents traveling in the flight path from the document feeder to the chassis and providing signals representing the lead and tail edges; and a controller coupled to the chassis, the document feeder and the set of photo-sensors, the controller calculating an expected profile for lead and tail edge signals from the photo-sensors as a function of a position of the chassis, a length of the documents, and the speed of the document feeder, the controller comparing the expected profile with the lead and tail edge signals from the set of photo-sensors and generating an error signal when the lead and tail edge signals are different from the expected profile by greater than a predetermined margin of error.