Flexographic printing method and flexographic printing apparatus having control means for driving printing roller

摘要

The present invention relates to a flexographic method of printing and a flexographic printing apparatus whereby the repeat length is greater than the circumference of the printing roller. This may be achieved by controlling the rotation of the printing roller as a non-printing zone of the printing roller passes a moving web such that an associated non-printed region formed on the web has a length that is greater than the non-printing zone. The rotation of the printing roller may be controlled by suspending the rotation of the printing roller or reducing the speed of rotation when the non-printing zone is in registration with the web and then increasing the speed of rotation to a predetermined printing speed as a printing zone of the printing roller comes into registration with the web.

主权项

1. A flexographic printing station for printing an image on a web comprising:
(a) a printing roller comprising at least one printing zone and at least one non-printing zone, wherein the at least one printing zone and the at least one non-printing zone are arranged on an outer surface of the printing roller and the at least one printing zone comprises a relief pattern; (b) an ink supply means for supplying ink to the relief pattern; (c) web line means for driving a web past the printing roller at a web line speed; (d) control means for rotatably driving the printing roller: (i) under a first rotational motion profile as the printing zone passes over the web, so as to print an image on the web; and (ii) under a second rotational motion profile, which is different from the first rotational motion profile as the non-printing zone passes over the web so as to form a non-printed region on the web that is longer than the circumferential length of the non-printing zone whereby either (A) random pattern repeat lengths are achieved by driving the printing roller to achieve random non-printed regions between successive images on the web printed by the at least one printing zone, or (B) variable pattern repeat lengths are achieved by driving the printing roller to achieve variable non-printed regions between successive images on the web printed by the at least one printing zone, and wherein the length of successive non-printed regions differ by an amount which exceeds an amount caused by registration tolerances.