ApplicationNo. 05/769056 filed on 02/16/1977
US Classes:101/450.1, Processes of lithographic printing101/211Processes
ExaminersPrimary: Coughenour, Clyde I.
Attorney, Agent or Firm
International ClassesB41M 3/00 (20060101)
B41M 1/00 (20060101)
B41M 1/06 (20060101)
G03F 5/22 (20060101)
G03F 5/00 (20060101)
G03F 5/12 (20060101)
AbstractAn improved two printing step process for reproducing visual subject matter including the making of a secondary printing plate with a positive image random pattern screen and printing a substrate sequentially and in registry with the secondary printing plate and a master printing plate made with a conventional half tone screen. The random pattern screen is a positive image phototransparency having a large plurality of irregularly shaped highlight areas and constrasting shadow areas per square inch, an optical density from about 0.17 to about 1.6, a contrast factor from about 0.75 to about 1.5 and a transparency factor from about 0.25 to about 0.60. The random pattern screen is made from a transparent plate having light disruptive projections on its surface. A negative and a positive phototransparency of the transparent plate are made while controlling exposure and developing conditions to produce a positive image screen having the desired characteristics.