Method of electrophotographically producing a multicolor image

Claim 1

THE METHOD OF ELECTROSTATIC PRINTING COMPRISING THE STEPS OF ELECTROPHOTOGRAPHICALLY PRODUCING A FIRST ELECTROSTATIC IMAGE ON A PHOTO-CONDUCTIVE INSULATING SURFACE, APPLYING TO SAID ELECTROSTATIC IMAGE A FIRST DEVELOPER POWDER HAVING A CHARACTERISTIC COLOR AND CONSISTING ESSENTIALLY OF PARTICLES OF PHOTOCONDUCTIVE ZINC OXIDE HAVING A SURFACE PHOTOCONDUCTIVITY OF AT LEAST 10-9 OHM-1/SQUARE/WATT/ CM.2 AT A WAVELENGTH OF ABOUT 3900 A., SAID PARTICLES HAVING A COATING THEREON OF A THERMOPLASTIC, ELECTROSCOPIC, INSULATING MATERIAL HAVING A MELTING POINT SUBSTANTIALLY WITHIN A RANGE OF FROM 90*C. TO 250*C. AND A VISCOSITY SUBSTANTIALLY WITHIN A RANGE OF FROM 45 TO 10,000 CENTIPOISES AT A TEMPERTURE SLIGHTLY ABOVE THE MELTING POINT OF SAID MATERIAL, APPLYING HEAT TO SAID DEVELOPER POWDER ON SAID INSULATING SURFACE TO CAUSE SAID COATING TO MELT AND FLOW TOWARD SAID SAID INSULATING SURFACE LEAVING SAID PARTICLES OF ZINC OXIDE PROTRUDING FROM SAID COATING MATERIAL AND LEAVING ONLY A THIN FILM OF COATING MATERIAL ON THE PORITONS OF SAID PARTICLES PROTRUDING FROM SAID COATING MATERIAL TO PROVIDE IN IMAGE AREAS ON SAID INSULATING SURFACE A PHOTOCONDUCTIVE INSULATING COATING, ELECTROPHOTOGRAPHICALLY PRODUCING A SECOND ELECTROSTATIC IMAGE ON SAID INSULATING SURFACE OVERLAPPING SAID PHOTOCONDUCTIVE INSULATING COATING, AND APPLYING TO SAID SECONE ELECTROSTATIC IMAGE A SECOND ELECTROSCOPIC DEVELOPER POWDER HAVING A CHARACTERISTIC COLOR DIFFERENT FROM THAT TO SAID FIRST DEVELOPER POWDER.

Claim 2

THE METHOD OF ELECTROSTATIC PRINTING COMPRISING THE STEPS OF ELECTROPHOTOGRAPHICALLY PRODUCING A FIRST ELECTROSTATIC IMAGE ON A PHOTO-CONDUCTIVE INSULATING SURFACE, APPLYING TO SAID ELECTROSTATIC IMAGE A FIRST DEVELOPER POWDER HAVING A CHARACTERISTIC COLOR AND CONSISTING ESSENTIALLY OF PARTICLES OF PHOTOCONDUCTIVE ZINC OXIDE HAVING A SURFACE PHOTOCONDUCTIVITY OF AT LEAST 10-9 OHM-1/SQUARE/WATT/ CM.2 AT A WAVELENGTH OF ABOUT 3900 A., SAID PARTICLES HAVING A COATING THEREON OF A THERMOPLASTIC, ELECTROSCOPIC, INSULATING MATERIAL HAVING A MELTING POINT SUBSTANTIALLY WITHIN A RANGE OF FROM 90*C. TO 250*C. AND A VISCOSITY SUBSTANTIALLY WITHIN A RANGE OF FROM 45 TO 10,000 CENTIPOISES AT A TEMPERTURE SLIGHTLY ABOVE THE MELTING POINT OF SAID MATERIAL, APPLYING HEAT TO SAID DEVELOPER POWDER ON SAID INSULATING SURFACE TO CAUSE SAID COATING TO MELT AND FLOW TOWARD SAID SAID INSULATING SURFACE LEAVING SAID PARTICLES OF ZINC OXIDE PROTRUDING FROM SAID COATING MATERIAL AND LEAVING ONLY A THIN FILM OF COATING MATERIAL ON THE PORITONS OF SAID PARTICLES PROTRUDING FROM SAID COATING MATERIAL TO PROVIDE IN IMAGE AREAS ON SAID INSULATING SURFACE A PHOTOCONDUCTIVE INSULATING COATING, ELECTROPHOTOGRAPHICALLY PRODUCING A SECOND ELECTROSTATIC IMAGE ON SAID INSULATING SURFACE OVERLAPPING SAID PHOTOCONDUCTIVE INSULATING COATING, AND APPLYING TO SAID SECONE ELECTROSTATIC IMAGE A SECOND ELECTROSCOPIC DEVELOPER POWDER HAVING A CHARACTERISTIC COLOR DIFFERENT FROM THAT TO SAID FIRST DEVELOPER POWDER.