Web indexing apparatus and overprinting machine

摘要

A label web overprinting machine in which the label web is indexed through the apparatus by two opposed rollers, one of which has a recess in its periphery defining a step and the other of which is movable through a small distance to form a nip for drawing the web forwardly through a printing station of the machine. A solenoid controls the movement of the movable roller and by a machine cycle operated switch the solenoid is energized to bring the one roller into substantial contact with the other at an instant when the recess of the one roller is directed towards the other roller. Immediately the step of the roller contacts the other roller, the web is indexed forward and the solenoid is subsequently deenergized by a photo-electric cell arrangement arranged to detect a particular indicia on a label or the downstream edge of a given label.