Abstract A system for controlling the flow of charged particles and for modulated aperture electrostatic printing. An apertured screen having substantially the entire surfaces formed of a dielectric material is charged with like charges over substantially all its surfaces to develop fringing fields in the apertures. The charge distributed across one side of the screen is selectively dissipated in accordance with a pattern to be reproduced thereby establishing a bipolar electrostatic latent image as a modification of the fringing fields for density control of a flow of charged particles directed through the screen. The screen may be formed with dielectric thicker on one face than the other to initially carry a higher potential and provide a uniform charge inequality or potential difference through the screen apertures, oriented to enhance the flow of charged particles through the screen. Full modulation control of particle flow is therefore possible with a single selective charge dissipation. For electrostatic reproduction a print-receiving medium is interposed in the modulated particle flow passing through the screen.
An electrostatic modulator for controlling the flow of charged particles comprising: an apertured member having substantially its entire surface of electrically insulative material including opposed first and second surface areas, said apertured member having an electrically conductive core between said first and second surface areas, said core held at fixed potential, said electrically insulative material at said first surface area being thicker than at said second surface area; means for establishing first and second equipotential layers of electrical charge on said first and second surface areas respectively, said first equipotential layer having a greater electrical potential than said second equipotential layer; and means for selectively diminishing the electrical potential of said first equipotential layer across a predetermined area in accordance with a pattern to be reproduced.
Claim 2
Dependent Claim
126 words
An electrostatic modulator for controlling the flow of charged particles comprising: an apertured member having substantially its entire surface of electrically insulative material including opposed first and second surface areas, said apertured member having an electrically conductive core between said first and second surface areas, said core held at fixed potential, said electrically insulative material at said first surface area being thicker than at said second surface area; means for establishing first and second equipotential layers of electrical charge on said first and second surface areas respectively, said first equipotential layer having a greater electrical potential than said second equipotential layer; and means for selectively diminishing the electrical potential of said first equipotential layer across a predetermined area in accordance with a pattern to be reproduced.
Claim 3
Dependent Claim
23 words
An electrostatic modulator as recited in claim 1 wherein said means for establishing first and second equipotential layers comprises a source of ions.
Claim 4
Dependent Claim
42 words
An electrostatic modulator as recited in claim 1 wherein said material comprising said first surface area is photoconductive and wherein said means for selectively diminishing includes means for projecting an optical image of the pattern to be reproduced on said photoconductive material.