US Patent 7556334 Methods and apparatus for aligning print heads

In a first aspect, a system is provided. The system includes (1) a stage adapted to move a substrate relative to print heads during printing; (2) at least one print head suspended from a support above the stage and adapted to be moveable in a plane above the stage; (3) a controller operable to rotate the print head about a center of the print head; and (4) an imaging system adapted to capture an image of the print head and to determine a center point of the print head based upon images of the print head captured as the print head is rotated. Numerous other aspects are provided.