Circumferential registration control system

摘要

A system for controlling registration in a Printing press between the moving web having repetitive print patterns and a work station operated cyclically in synchronization with the press. The system includes a photoelectric scanner having a variable sensitivity, a position pulse generator with a backup accumulating device, a motorized compensator for controlling the longitudinal position of the web relative to the work station and a digital control circuit for driving the compensator to correct misregistration. The control system counts position pulses during each cycle of the work station, defines a monitoring period during which marks and repetitive print patterns are scanned and signals differences between the cycles of the print markings and the work station by sampling at the occurrence of each mark, a digital number which corresponds to the instantaneous position of the work station and its cycle. To enhance selectivity the system employs a variable sensitivity scanner, a variable duration window or monitoring period and automatic setup apparatus that synchronizes the system to those portions of the web which are most distinctive and uncluttered. Many other features and options are described.