Electrography

Claim 2

An electrographic recording apparatus for producing, on a layer of insulating material in contact with an electrically conductive backing member, an electrostatic charge image corresponding to an image to be recorded, comprising: image grid means having electrically conductive and electrically insulating areas for defining said image to be recorded; control grid means arranged in spaced and generally parallel relation to said image grid means and to said backing member; means for individually biasing each of said image grid means, control grid means and backing member to a potential for establishing electrical fields of different strength between each of said areas, respectively, and said backing member; and means for directing a flow of ions toward said image grid means, control grid means and layer of insulating material, whereby said electrical fields modulate said flow of ions through said image and control grid means to produce said electrostatic charge image on said layer of insulating material.

Claim 3

The apparatus in accordance with claim 1 wherein said image grid means comprises at least one electrically conductive core completely coated with a layer of electrically insulating material at least a part of which is responsive to imagewise exposure to radiant energy to form said conductive and insulating areas.

Claim 4

The apparatus in accordance with claim 2 wherein said radiant-energy-responsive part of said insulating material is photoconductive.

Claim 5

The apparatus in accordance with claim 1 wherein said image grid means comprises at least one electrically conductive core completely coated with a photoconductive insulating material responsive to imagewise exposure to radiant energy to form said conductive and insulating areas.

Claim 6

The apparatus in accordance with claim 1 wherein said control grid means comprises at least one electrically conductive control grid arranged in spaced and generally parallel relation to one side of said image grid means.

Claim 7

The apparatus in accordance with claim 5 wherein said one control grid is arranged between said image grid means and said backing member.

Claim 8

The apparatus in accordance with claim 1 wherein said control grid means comprises an electrically conductive grid Arranged to that side of said image grid means that is opposite from said backing member.

Claim 9

The apparatus in accordance with claim 1 wherein said control grid means comprises a pair of electrically conductive grids, one of which is located between one side of said image grid means and said insulating surface and the other of which is located to the opposite side of said image grid means.

Claim 10

The apparatus in accordance with claim 1 wherein said directing means comprises a corona discharge device.

Claim 11

The apparatus in accordance with claim 1 wherein the polarity of the potential applied to said image and control grid means and said backing member by said biasing means is the same as that of the ions in said flow of ions.

Claim 12

An electrographic recording apparatus for producing, on a layer of insulating material in contact with an electrically conductive backing member, an electrostatic charge image corresponding to an image to be recorded, comprising: an image grid comprising an electrically conductive core sequentially connectable to sources of different potential relative to said backing member and completely covered with a coating of electrically insulating material that is a photoconductive insulating material on at least one side of said core, said grid being arranged in spaced and generally parallel relation to said backing member; a control grid that is electrically conductive, sequentially connectable to sources of different potential relative to said backing member and arranged in spaced and generally parallel relation to said image grid on the side thereof that is opposite said backing member; means for generating ions to provide a first and a second flow of ions toward said control and image grids; means for connecting each of said core and control grids to one of its respective sources of potential, while said first flow of ions is being generated, whereby said photoconductive material will be uniformly charged to a potential generally equivalent to that on said control grid; means for imagewise exposing said photoconductive insulating material, after said image grid has been uniformly charged, to create electrically conductive and insulating areas thereon corresponding to said image to be recorded, and means for connecting each of said core and control grid to another of its respective sources of potential, while said second flow of ions is being generated for establishing electrical fields of different strength between each of said areas respectively and said backing member, whereby said fields will modulate said second flow of ions through said image and control grids to produce said electrostatic image on said layer of insulating material.

Claim 13

An electrographic recording apparatus for producing, on a layer of insulating material in contact with an electrically conductive backing member, an electrostatic charge image corresponding to an image to be recorded, comprising: an image grid comprising an electrically conductive core sequentially connectable to sources of different potential relative to said backing member and completely covered with a coating of electrically insulating material that is a photoconductive insulating material on at least one side of said core, said grid being arranged in spaced and generally parallel relation to said backing member; a control grid that is electrically conductive, sequentially connectable to sources of different potential relative to said backing member and arranged in spaced and generally parallel relation to said image grid on the side thereof that is opposite said backing member; means for generating ions to provide a first and a second flow of ions toward said control and image grids; means for connecting each of said core and control grids to one of its respective sources of potential, while said first flow of ions is being generated, whereby said photoconductive material will be uniformly charged to a potential generally equivalent to that on said control grid; means for imagewise exposing said photoconductive insulating material, after said image grid has been uniformly charged, to create electrically conductive and insulating areas thereon corresponding to said image to be recorded, and means for connecting each of said core and control grid to another of its respective sources of potential, while said second flow of ions is being generated for establishing electrical fields of different strength between each of said areas respectively and said backing member, whereby said fields will modulate said second flow of ions through said image and control grids to produce said electrostatic image on said layer of insulating material.

Claim 14

The apparatus in accordance with claim 11 wherein, during said first flow of ions, the potential applied to said image grid by said connecting means is of opposite polarity to said ions, and the potential applied to said control grid is substantially equal to that of said backing member.

Claim 15

The apparatus in accordance with claim 11 wherein, during said second flow of ions, the potential applied respectively to said image and control grids by said connecting means is of the same polarity as said ions.