Checking printing forms e.g. of non-impact printer for quality control prior to printing - using photoelectric or piezoelectric scanner to generate digital signals which reproduce surface structure and position of register marks from each form in set, and comparing with stored values

摘要

Register deviations of the structured surfaces of printing plates from the register marks produced on the printing plates from a theoretical value are determined with the aid of a computer. Using a scanner (2,3,4,5) from each printing appts. (1) of a set of printing appts., digital signals are obtained, which reproduce the structure of the surface and the position of register marks (8) and from these signals the register deviations are determined. Photo-electric image signals are produced, which are compared with theoretical values, located in an addressable memory, connected to a digital computer (9) for picture processing. The scanner probes the surface by piezoelectric contact. ADVANTAGE - Checks printing forms on reduced cost basis.