Patent ID: 6042111
Filing Date: 2000-03-28
Classification: B65H

Abstract:
A paper jam shutdown pre-warning method of determining paper sheet slip in a sheet transport system for transporting paper sheets on which an output image is to be printed in a printing apparatus, the method comprising:prior to an initial use of the printing apparatus by an end-user, conveying an initial paper sheet through said sheet transport system;detecting a plurality of initial conditions representing times at which said initial paper sheet passes a plurality of successive sensing locations within the sheet transport system;establishing a plurality of jam detection windows that are respectively defined by a time period in which a subsequent paper sheet is to pass said plurality of successive sensing locations, said jam detection windows defined to coincide respectively with the plurality of initial conditions such that each of said jam detection windows is non-symmetrically defined about said initial condition respectively coincident therewith;conveying a subsequent paper sheet through said sheet transport system for purposes of printing information on said subsequent paper sheet;sensing a sense event at each of the plurality of successive sensing locations, said sense event defined by passage of an edge of said subsequent paper sheet past said sensing location;at each of said successive sensing locations, deriving slip of the subsequent paper sheet in the sheet transport system by comparing the position of the sense event with the initial condition in said respective jam detection window and with any slip derived in association with an upstream jam detection window;recording information that describes said derived slip in a memory; and,accessing said recorded information that describes said derived slip to pre-warn of an imminent paper jam prior to an occurrence of said imminent paper jam.