Method of electrostatic powder gravure printing and apparatus therefor

Claim 1

THE METHOD OF GRAVURE PRINTING WHEREIN AN IMAGE IS FORMED ON A SUBSTRATE WITH A DRY PRINTING POWDER WHICH COMPRISES: (A) FURNISHING TO CELLS ETCHED IN THE SURFACE OF A ROTATING GRAVURE CYLINDER A PRINTING POWDER ADAPTED TO RECEIVE AND RETAIN AN APPLIED ELECTROSTATIC CHARGE; (B) CREATING AN ELECTROSTATIC FIELD AT A POINT TRAVERSED BY THE SURFACE OF SAID GRAVURE CYLINDER AFTER THE PRINTING POWDER IS FURNISHED TO THE CELLS ETCHED THEREIN; (C) FEEDING A SUBSTRATE SO THAT IT TRAVELS THROUGH SAID FIELD AT SUBSTANTIALLY THE SAME RATE AND DIRECTION AS THE ETCHED SURFACE OF SAID GRAVURE CYLINDER AND IN PROXIMITY TO SAID ETCHED SURFACE; (D) APPLYING AN ELECTROSTATIC CHARGE TO THE POWDER IN SAID CELLS AT A POINT LOCATED BETWEEN THE POINT WHERE THE POWDER IS FURNISHED TO SAID CELLS AND THE POINT WHERE SAID CELLS TRAVEL THROUGH SAID ELECTROSTATIC FIELD; (E) ROTATING SAID CYLINDER AT SUCH SPEED THAT A SUBSTANTIAL PORTION OF THE ELECTROSTATIC CHARGE APPLIED TO SAID POWDER IS RETAINED ON SAID POWDER AS IT ENTERS SAID ELECTROSTATIC FIELD, SO THAT SAID PRINTING POWDER IS TRANSFERRED FROM SAID CELLS TO SAID SUBSTRATE UNDER THE INFLUENCE OF SAID ELECTRASTIC FIELD; AND (F) THEN FIXING THE POWDER ON THE SURFACE OF SAID SUBSTRATE.

Claim 2

THE METHOD OF GRAVURE PRINTING WHEREIN AN IMAGE IS FORMED ON A SUBSTRATE WITH A DRY PRINTING POWDER WHICH COMPRISES: (A) FURNISHING TO CELLS ETCHED IN THE SURFACE OF A ROTATING GRAVURE CYLINDER A PRINTING POWDER ADAPTED TO RECEIVE AND RETAIN AN APPLIED ELECTROSTATIC CHARGE; (B) CREATING AN ELECTROSTATIC FIELD AT A POINT TRAVERSED BY THE SURFACE OF SAID GRAVURE CYLINDER AFTER THE PRINTING POWDER IS FURNISHED TO THE CELLS ETCHED THEREIN; (C) FEEDING A SUBSTRATE SO THAT IT TRAVELS THROUGH SAID FIELD AT SUBSTANTIALLY THE SAME RATE AND DIRECTION AS THE ETCHED SURFACE OF SAID GRAVURE CYLINDER AND IN PROXIMITY TO SAID ETCHED SURFACE; (D) APPLYING AN ELECTROSTATIC CHARGE TO THE POWDER IN SAID CELLS AT A POINT LOCATED BETWEEN THE POINT WHERE THE POWDER IS FURNISHED TO SAID CELLS AND THE POINT WHERE SAID CELLS TRAVEL THROUGH SAID ELECTROSTATIC FIELD; (E) ROTATING SAID CYLINDER AT SUCH SPEED THAT A SUBSTANTIAL PORTION OF THE ELECTROSTATIC CHARGE APPLIED TO SAID POWDER IS RETAINED ON SAID POWDER AS IT ENTERS SAID ELECTROSTATIC FIELD, SO THAT SAID PRINTING POWDER IS TRANSFERRED FROM SAID CELLS TO SAID SUBSTRATE UNDER THE INFLUENCE OF SAID ELECTRASTIC FIELD; AND (F) THEN FIXING THE POWDER ON THE SURFACE OF SAID SUBSTRATE.