| 摘要 |
<p>A printing system incorporates a re-usable image-carrying printing surface. A material which forms a thin hydrophobic layer is arranged by various techniques over a substantially hydrophilic printing surface in a configuration which defines the desired latent image in terms of exposed, contiguous hydrophilic and hydrophobic areas. Depending upon the configuration of the layers, either an aqueous or oleo ink may be used to develop and print an image. If desired, the layer configuration may be replaced by a different configuration without substantial interruption to the printing process. No photo-induced chemical reaction or latent image developing steps are required at any time. In a typical apparatus, the hydrophilic surface of a printing roll (10) is cleaned (12-16) and coated with a hydrophobic material (20-24), and the hydrophobic material is physically removed from selected areas by a computer-addressable spark discharge (26-30), laser or other device to form a latent image. A fountain liquid is subsequently applied (40), followed by an ink (50), and the ink image is transferred to a substrate to be printed either directly (8) with the help of a pressure roll (6) or indirectly (6A) through an offset roll (6).</p> |
