Special intaglio printing process for preventing forgery of securities

Claim 1

An intaglio printing process for preventing forgery or counterfeiting of securities or the like comprising: providing a gravure printing plate having a grid pattern representing an original design and made up of a plurality of small discrete recesses on the plate surface, said recesses varying in depth for reproducing fine continuous gradations of color, highlight or shadow of the original design on a surface printed by the inked plate, said plate also having elongate engraved grooves cut into the plate surface and extending across a plurality of said gravure recesses, said engraving grooves varying in depth and width and representing a complex pattern for preventing forgery or counterfeiting; positioning said printing plate on a printing plate cylinder; inking said printing plate with ink having a viscosity of a normal intaglio engraving printing ink; wiping off surplus ink from the plate surface; feeding a sheet between the inked printing plate and an impression cylinder in contact with said printing plate cylinder to obtain on said sheet a printed reproduction of said original design including said complex pattern for preventing forgery or counterfeiting.