Method and apparatus for object surveillance along a transport path

摘要

A method and apparatus for document surveillance along a transport path in a mail sorting machine includes using a plurality of sequentially positioned photocells affixed along the transport path to detect document separation and jamming events through the application of assigned document identification and message transfer schemes whereby one sensor detects an edge of the document and transfers the document identifier and a shaft encoder count to the next sensor along the transport path in the form of a message. A message queue for each sensor is maintained to detect improper document leading edge and trailing edge conditions. A series of surveillance modules operates on a multi-tasking basis through a primary master processor.