(19)
(11) EP 0 030 642 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
26.05.1982 Bulletin 1982/21

(43) Date of publication A2:
24.06.1981 Bulletin 1981/25

(21) Application number: 80107228

(22) Date of filing: 20.11.1980
(84) Designated Contracting States:
DE FR GB

(30) Priority: 17.12.1979 US 103965

(71) Applicant: International Business Machines Corporation
 ()

(72) Inventors:
  • Aviram, Ari
     ()
  • Cahill, John Gregory
     ()
  • Hauge, Peter Swift
     ()
  • Pennington, Keith Samuel
     ()

   


(54) Lithographic printing plate and method for producing the same


(57) An improved lithographic printing plate includes a substrate layer (2) of a nonconducting, hydrophobic material, an intermediate film (3) of conducting, hydrophilic material such as aluminum and a top protective film (5) of relatively hard hydrophilic dielectric material, such as aluminum oxide. A printing image is formed in the lithographic printing plate by an electroerosion process wherein erosion electrodes (7) are pulsed with voltage to break down the dielectric film (5) in areas adjacent to the erosion electrodes (7) and to evaporate or otherwise remove corresponding portions of the conducting film (3), thereby creating holes (8) that extend through the dielectric (5) and conducting (3) films and that expose portions of the surface of the underlying hydrophobic substrate (2).






Search report