Abstract: 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.

Abstract: A system for detecting breaks in a web moving through a predetermined area including a scanner head assembly having an infrared emitter, optical filtering and an adjustable receiver for detecting the presence or absence of reflecting infrared radiation from an object within the scanner path. The scanner control system provides a power source for the emitter which pulsates at a predetermined frequency and low duty cycle, a receiver circuit incorporating selective filtering, and a phase-locked detector loop tuned to the emitter frequency for optimum selectivity and performance in the face of varying ambient light conditions. A scanner head having a linearly adjustable operating range is employed for tailoring the system to a wide range of web locations and conditions.