Printing image carriers which are conventional at the present time for use in surface printing are normally produced photochemically before mounting on the press so that when the printing image carrier is changed idle press time and labor costs are involved.
At the present time it is possible for electronically stored data to be used for the production of the printing image carrier, such data comprising all the required information.
The European patent publication 101,266, to which U.S. Pat. Nos. 4,718,340 and 4,729,310, Love et al, in part correspond, describes a printing press, in which print information in an electronically encoded form may be used to produce or reconfigure, that is, reprogram the printing image carrier while on the press. This means that changing of the printing image carrier and the accompanying idle time of the press and the labor costs no longer occur.
The press in accordance with the said publication is characterized in that the printing image carrier cylinder has a hydrophilic surface which is washed by means forming part of the press; is then coated with a hydrophobic layer; and is then subjected, for example, to a laser beam. The renewal or reconfiguration of the printing image carrier requires a short interruption of the printing process for washing, coating and laser operation. During such changing or renewal of the printing image on the printing image carrier the previously existing ink layer is washed off and a new hydrophobic layer is produced, which is then locally removed with the laser beam in accordance with the printing image. The laser beam is controlled by encoded print information.
In accordance with the U.S. Pat. No. 4,872,962, assigned to a related company of the assignee of this application, to which German Patent 37 05,439 corresponds, the printing image can be produced or modified on the press without the intermediate step using optical means, by employing an electrical control means responding to electronically stored information. The press need not be stopped to change the printing image carrier. In this method the printing image carrier is completely coated with an electrically conductive polymer. The production of changes in the printing image carrier to result in image and non-image areas is caused by electrochemical action on the polymer layer, which may be in hydrophilic or hydrophobic form.