US Patent 7668784 Printing of postal indicia and detection thereof

The invention provides a method of detection of an imprint of a postal indicium at a location on a mail piece. The method involves utilizing a sensor to scan along a band on the mail piece to detect a sequence of transitions between light and dark reflectance areas within a band extending across the said location. AN indication of the presence of the imprint of the postal indication is generated in response to detection of a transition succeeding a predetermined number of initial transitions at a start of the sequence of transitions.