Electrostatic printer with powder feed structure inside stencil drum

Claim 1

IN ELECTROSTATIC PRINTING APPARATUS THAT INCLUDES A PRINTING SCREEN HAVING A PERFORATED PORTION ADAPTED TO RECEIVE THEREON PRINTING POWDER FOR MOVEMENT THROUGH THE OPENINGS IN SAID PORTION INTO AN ELECTROSTATIC FIELD ESTABLISHED IN AN AIR GAP BETWEEN SAID SCREEN AND AN ARTICLE TO BE PRINTED UPON FOR CONDUCTION OF THE POWDER SO MOVED ACROSS SAID AIR GAP, THE COMBINATION OF: (A) A HORIZONTALLY DISPOSED, STATIONARY LAYER OF MATERIAL OVER WHICH A BED OF PRINTING POWDER IS ADAPTED TO BE SUPPORTED, SAID MATERIAL BEING FORMED WITH SUBSTANTIALLY UNIFORMLY DISTRIBUTED TORTUOUS ADJACENT PASSAGEWAYS EXTENDING THERETHROUGH FROM TOP TO BOTTOM OF SUFFICIENT SIZE TO PASS THE PARTICLES OF SAID POWDER DOWNWARDLY THERETHROUGH FROM SAID BED FOR SUBSTANTIALLY UNIFORM DISCHARGE FROM THE UNDERSIDE OF SAID LAYER UPON ADMINISTRATION OF SHOCKS TO SAID LAYER AND BODY; (B) SAID LAYER HAVING OUTER EDGES, AND A RIGID LAYERSUPPORT CONNECTED WITH SAID EDGES SUPPORTING SAID LAYER WITH THE AREA THEREOF INWARDLY OF ITS EDGES SPACED OVER SAID PORTION OF SAID SCREEN FOR PASSAGE OF SAID POWDER THROUGH SAID PASSAGEWAYS AND FOR DISCHARGE AND DEPOSIT ON SAID PORTION; (C) A POWDER SUPPORTING SCREEN DISPOSED BETWEEN SAID BED OF PRINTING POWDER AND SAID LAYER SUPPORTING SAID BED OF PRINTING POWDER OVER SAID LAYER AND THROUGH THE OPENINGS OF WHICH SCREEN POWDER PASSES FROM SAID BED TO SAID LAYER, SAID SCREEN BEING INELASTIC TO STRETCHING AND HELD AGAINST DISTORTION UNDER THE WEIGHT OF SAID BED OF POWDER; (D) MOVABLE SHOCK-ADMINISTERING MEANS OPERATIVELY CONNECTED WITH SAID LAYER FOR ADMINISTERING SHOCKS THERETO AND TO SUCH BED FOR CAUSING DOWNWARD MOVEMENT OF POWDER OF SAID BED THROUGH SAID PASSAGEWAYS AND SAID DISCHARGE THEREFROM UNDER THE COMBINED INFLUENCE OF SAID SHOCKS AND GRAVITY.