Method and apparatus for printing onto a continuously advancing web of

Abstract

In an apparatus for printing on a web of work material continuously advanced in an X coordinate direction at a velocity v.sub.wx, at least one print head having a plurality of print elements arranged in a scanning array extending in the X direction is repetitively movable relative to the apparatus. The scanning array moves at a velocity v.sub.a along a path that includes at least one scan segment and at least one repositioning segment. As the scanning array traverses the scan segment it has a first velocity component v.sub.ax in the X direction, and a second velocity component v.sub.ay in a Y direction perpendicular to the X direction. The first velocity component v.sub.ax is equal to the velocity v.sub.wx so that the scanning array in traversing the scan segment, scans a swath on the web parallel to the Y direction, having a swath height h.sub.s. The velocity component v.sub.ay is such that in the time taken for the array to move along the full extent of the scan segment the web advances a distance h.sub.w in the X direction that is less than h.sub.s. The array then travels along the repositioning segment such that prior or equal to a time taken for the web to advance a distance d=h.sub.s -h.sub.w the print head is positioned for movement along the scan segment, thereby causing successive swaths of the web scanned by the array to be positioned immediately adjacent to one another.