Method and apparatus for imaging a lithographic printing plate

摘要

A lithographic printing plate has a hydrophilic substrate and an oleophilic coating. The plate is simultaneously imaged and developed by applying a solvent for the coating in an image-wise pattern using a jet printer. The oleophilic coating is thereby removed in those areas where the solvent has been jetted exposing the hydrophilic substrate and leaving the residual oleophilic coating in the form of the desired positive image. Because the jetting of the solvent in the image-wise pattern may not apply solvent at the leading and trailing ends of the plate, a strip of solvent is applied to these ends by a separate applicator. Also, separate applicators may apply the solvent to the side edges of the plate. The residual oleophilic coating may be post treated to insolubilize and/or harden the image.