Electrostatic color printing utilizing discrete potentials
AssigneeRank Xerox Ltd.
InventorRobert Robertson
Life of this patent
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Abstract
An apparatus in which an electrostatic latent image is developed simultaneously in two colors. A first portion of the latent image has a potential greater than a first threshold with a second portion thereof having a potential less than a second threshold. The second threshold is less than the first threshold. Particles of a first color are applied to the first portion of the latent image with particles of a second color being applied to the second portion of the latent image. The electrostatic latent image is discharged to a potential less than the second potential and portions thereof having a potential greater than the second threshold by a pre-selected level.
Claims11
An apparatus for rendering visible an electrostatic latent image having a portion thereof with an image potential greater than a first threshold and a second portion thereof with an image potential less than a second threshold, the second threshold being less than the first threshold, wherein the improvement includes:
- a developer unit applying particles of a first color to the first portion of the latent image and particles of a second color to the second portion of the latent image
- further including means for selectively discharging the electrostatic latent image to a potential less than the second threshold in portions thereof having a potential greater than the second threshold by a preselected level.
An electrophotographic printing machine for reproducing an original document having a first color, a second color, and a background color therein, including:
- a photoconductive member;
- means for charging said photoconductive member to a substantially uniform potential;
- means for projecting a light image of the original document onto the charged portion of said photoconductive member recording an electrostatic latent image having a first image potential corresponding to the first color, a second image potential less than the first image potential and corresponding to the second color, and a third image potential less than the second image potential and corresponding to the background color;
- and
- means for applying particles corresponding in color to the color of the first color of the original document to the portion of the electrostatic latent image having the first image potential and particles corresponding in color to the color of the background of the original document to the portion of the electrostatic latent image having the third image potential with the portion of the electrostatic latent image having the second image potential remaining void of particles.
Dependencies are inferred from the claim text.