Web transport system

Abstract

A web transport and metering system provides the continuous delivery of a web to a developer while providing intermittent delivery of the web to an exposure station. An exposure station is defined between a pair of spaced-apart rolls, and a supply of web material leads to the exposure station over a loop-forming roller carried on a movable carriage or truck. A second loop-forming roller on the carriage receives the web from the second roll of the exposure station and delivers the web to a continuously running developer. The carriage is movable on guides or tracks parallel to the plane of the exposure station between first and second positions, which positions are defined by limit switches which operate a controllable brake on one of the exposure station rolls to interrupt movement of the web at the exposure station. During such interrupted movement, the developer draws web material from the second loop, and the movement of the carriage pulls web material into the first loop. A tension or return spring on the carriage causes the carriage to return to its first movement, when the brake at the exposure station is released, thereby causing translation of the web material through the exposure station and out of the first loop into the second loop. A tension drag or brake on the supply roll assures a desired tension in the web throughout the loops, and permits continuous feed through the loops to the continuous developer, when the exposure station brake is released. The invention further includes a means of reversing the system to reduce the material usage on single exposure runs.