Off-line web finishing system with splice and missing mark stability

Abstract

An off-line web finishing system performs plural functions on a pre-printed and rewound web at a series of pieces of equipment arranged in a line. Tension in the web is set at a variable infeed at a substantially constant value that is sufficient to facilitate handling of the web. A common web-transport system drives all draw rolls in the line in unison, at substantially the same speed, and without slippage between the web and the rolls. A second drive system, preferably one using a second drive shaft, rotates the function cylinders of one or more registration sensitive pieces of equipment in unison. A continuously adjustable variable transmission is operatively connected between the secondary line shaft and a main line shaft for the web transport. A control system adjusts the variable transmission. It includes a central microprocessor, an optical scanner associated with each function cylinder, and an encoder to measure the speed of rotation of the function cylinder. Each scanner senses adjacent registration marks on the web that define each impression. Control logic compares the sensed speed in the time interval T for one impression to pass on and produces an output control signal if the proper speed is not sensed and if the misregistration is less than a predetermined limit.