Abstract

Apparatus for controlling the alignment, in a lateral (cross-track) direction, of a web moving along a path to minimize lateral deviation between successive discrete areas of such web. The apparatus includes a steering roller for supporting the web for movement along such path. The steering roller is rotatable about an axis perpendicular to the plane of the span of the web approaching the steering roller. As the web moves along the path, the lateral position of a marginal edge of the web relative to a reference plane is sensed. When such lateral edge position is at either of two spaced predetermined locations relative to such reference plane, signals indicative of the presence of such edge at such locations are produced. The steering roller, in response to such signals, is rotated about the axis perpendicular to the plane of the span of the web approaching the steering roller to steer the web and thereby cause the lateral position of the edge of the web to progress from the predetermined location at which the edge was sensed to the other predetermined location as the web moves along its path.