Printed web fault monitor - has paired sensors to monitor print repeat on web with deviations recorded to show location of web faults

摘要

The system to detect faults in printed webs, partic. to identify where webs have been joined together at a rotary press, compares the signals of two or more sensors which monitor the repeated print pattern on the web and generate a control signal on a deviation. Each sensor (1) has a second sensor (2) at a gap from it, in the direction of web travel, which is the repeat length or a multiple of it for the print applied to the web (4). When a difference is detected in the sensor signals, the location of a fault (7) is determined and held. ADVANTAGE - The method gives a simple and accurate identification of the location of the glued ends of the web, for removal before the printed web is folded and bound.