US4068938A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrostatic color printing utilizing discrete potentials
Assignee: Xerox Ltd
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Filing: 1975-06-16
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Granted: 1978-01-17
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Expires: 1995-06-16
Abstract
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.
Inventors
- 👤 Robert Robertson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:21
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/01; G03G15/0142; G03G15/0147; G03G15/0152; G03G15/0163; G03G15/06; G03G15/10; G03G15/101; G03G15/102
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
113 words
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.
Claim 2
Independent Claim
113 words
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.
Claim 3
Dependent Claim
23 words
An apparatus as recited in claim 1, wherein said discharging means includes a conductive roller electrically biased to a preselected potential and magnitude.
Claim 4
Dependent Claim
179 words
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.
Claim 5
Dependent Claim
179 words
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.
Claim 6
Dependent Claim
31 words
A printing machine as recited in claim 3, further including means for transferring the particles from the electrostatic latent image recorded on said photoconductive member to a sheet of support material.
Claim 7
Dependent Claim
27 words
A printing machine as recited in claim 4, wherein the sheet of support material is of a color corresponding to the second color of the original document.
Claim 8
Dependent Claim
23 words
A printing machine as recited in claim 5, further including means for fixing substantially permanently th particles to the sheet of support material.
Claim 9
Dependent Claim
103 words
A printing machine as recited in claim 6, wherein said particle applying means includes: a first grooved roller having a conductive surface electrically biased to the potential of sufficient magnitude and polarity so that uncharged liquid ink in the grooves below the crests thereof render the portion of the electrostatic latent image having the first image potential visible; and a second grooved roller having a conductive surface electrically biased to a potential of sufficient magnitude and polarity so that uncharged liquid ink in the grooves below the crest thereof renders the portion of the electrostatic latent image having the third image potential visible.
Claim 10
Dependent Claim
42 words
A printing machine as recited in claim 7, further including means for selectively discharging the electrostatic latent image to a potential less than the third image potential in portions having a potential greater than the third image potential by a preselected level.
Claim 11
Dependent Claim
24 words
A printing machine as recited in claim 8, wherein said discharging means includes a conductive roller electrically biased to a preselected potential and magnitude.
Claim 12
Dependent Claim
42 words
A printing machine as recited in claim 6, further including means for selectively discharging the electrostatic latent image to a potential less than the third image potential in portions having a potential greater than the third image potential by a preselected level.
Claim 13
Dependent Claim
24 words
A printing machine as recited in claim 10, wherein said discharging means includes a conductive roller electrically biased to a preselected potential and magnitude.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-01-16 | 1981-07-18 | 1982-01-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-01-16 | 1985-07-18 | 1986-01-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-01-16 | 1989-07-18 | 1990-01-17 | $7700.00 | Window Closed / Lapsed |