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US3901698A Expired / Lapsed US ⏱️ 0.0 years remaining

Method of reversal development using two electrostatic developers

Assignee: Xerox Ltd
•
Filing: 1973-12-20
•
Granted: 1975-08-26
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Expires: 1993-12-20
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Abstract

Abstract Process for electrophotographic discharge area development is provided comprising uniformly electrostatically charging a photoconductive insulating layer, exposing said photoconductive layer to an original image pattern of light and shadow, said photoconductive layer being discharged in areas corresponding to the light areas of the imaging pattern and retaining charge in areas corresponding to the shadow areas of the image pattern, said charged and discharged areas of said photoconductive layer resulting in the formation of an electrostatic latent image corresponding to the original image pattern, developing said electrostatic latent image with a first developer containing a toner which is substantially invisible when viewed against the photoconductive layer, said toner having the same or opposite polarity as that of charged areas on the photoconductive layer, whereby the toner preferentially adheres to areas of said layer wherein charged and discharged areas meet, such areas exhibiting an electric field gradient, thereafter, developing said electrostatic latent image with a second developer containing a colored toner which is visible when viewed against the photoconductive layer by contacting said layer with said second developer, said toner having the same polarity as that of the charged areas on the photoconductive layer, simultaneously establishing a potential between said second developer and the photoconductive layer, thereby depositing the color toner in the discharged areas of said layer forming a reversal image of the original image pattern.

Inventors

  • 👤 Osamu Fukushima
  • 👤 Sadao Osawa
  • 👤 Takao Komaki
  • 👤 Masamichi Sato

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-30 04:17
CPC Classifications
G; G03; G03G; G03G13/00; G03G13/06; G03G9/00; G03G9/08

Claims Analysis

Total Claims: 9
Claim 1
Independent Claim 240 words
PROCESS FOR ELECTROPHOTOGRAPHIC DISCHARGE AREA DEVELOPMENT CONSISTING ESSENTIALLY OF UNIFORMLY ELECTROSTATICALLY CHARGING A PHOTOCONDUCTIVE INSULATING LAYER, EXPOSING SAID, PHOTOCONDUCTIVE LAYER TO AN ORIGINAL IMAGE PATTERN OF LIGHT AND SHADOW, SAID PHOTOCONDUCTIVE LAYER BEING DISCHARGED IN AREAS CORRESPONDING TO THE LIGHT AREAS TO THE IMAGEING PATTERN AND RETAINING CHARGE IN AREAS CORRESPONDING TO THE SHADOW AREAS OF THE IMAGE PATTERN, SAID CHARGED AND DISCHARGED AREAS OF SAID PHOTOCONDUCTIVE LAYER RESULTING IN THE FORMATION OF AN ELECTROSTATIC LATENT IMAGE CORRESPONDING TO THE ORIGINAL IMAGE PATTERN, DEVELOPING SAID ELECTROSTATIC LATENT IMAGE WITH A FIRST DEVELOPER CONTAINING A TONER WHICH IS SUBSTANTIALLY INVISIBLE WHEN VIEWED AGAINST THE PHOTOCNDUCTIVE LAYER, SAID TONER HAVING THE SAME OR OPPOSITE POLARITY AS THAT OF CHARGED AREAS ON THE PHOTOCONDUCTIVE LAYER AND HAVING INSULATING PROPERTIES TO PREVENT RELEASE OF ITS CHARGE TO THE PHOTOCONDUCTIVE LAYER WHEREBY THE TONER PREFERENTIALLY ADHERES TO AREAS OF SAID LAYER WHEREIN CHARGED AN DISCHARGED AREAS MEET, SUCH AREAS EXHIBITING AN ELECTRIC FIELD GRADIENT, THEREAFTER, DEVELOPING SAID ELECTROSTATIC LATENT IMAGE WITH A SECOND DEVELOPER CONTAINING A COLORED TONER WHICH IS VISIBLE WHEN VIEWED AGAINST THE PHOTO CONDUCTUVVE LAYER BY CONTACTING SAID LAYER WITH SAID SECOND DEVELOPER, SAID TONER HAVING THE SAME POLARITY AS THAT OF THE CHARGED AREAS ON THE PHOTOCONDUCTIVE LAYER SIMULTANEOUSLY ESTABLISHING A POTENTIAL BETWEEN SAID SECOND DEVELOPER AND THE PHOTOCONDUCTIVE LAYER THEREBY DEPOSITING THE COLOR TONER IN THE DISCHARGED AREAS OF SAID LAYER FORMING A REVERSAL IMAGE OF THE ORIGINAL IMAGE PATTERN.
Claim 2
Dependent Claim 240 words
PROCESS FOR ELECTROPHOTOGRAPHIC DISCHARGE AREA DEVELOPMENT CONSISTING ESSENTIALLY OF UNIFORMLY ELECTROSTATICALLY CHARGING A PHOTOCONDUCTIVE INSULATING LAYER, EXPOSING SAID, PHOTOCONDUCTIVE LAYER TO AN ORIGINAL IMAGE PATTERN OF LIGHT AND SHADOW, SAID PHOTOCONDUCTIVE LAYER BEING DISCHARGED IN AREAS CORRESPONDING TO THE LIGHT AREAS TO THE IMAGEING PATTERN AND RETAINING CHARGE IN AREAS CORRESPONDING TO THE SHADOW AREAS OF THE IMAGE PATTERN, SAID CHARGED AND DISCHARGED AREAS OF SAID PHOTOCONDUCTIVE LAYER RESULTING IN THE FORMATION OF AN ELECTROSTATIC LATENT IMAGE CORRESPONDING TO THE ORIGINAL IMAGE PATTERN, DEVELOPING SAID ELECTROSTATIC LATENT IMAGE WITH A FIRST DEVELOPER CONTAINING A TONER WHICH IS SUBSTANTIALLY INVISIBLE WHEN VIEWED AGAINST THE PHOTOCNDUCTIVE LAYER, SAID TONER HAVING THE SAME OR OPPOSITE POLARITY AS THAT OF CHARGED AREAS ON THE PHOTOCONDUCTIVE LAYER AND HAVING INSULATING PROPERTIES TO PREVENT RELEASE OF ITS CHARGE TO THE PHOTOCONDUCTIVE LAYER WHEREBY THE TONER PREFERENTIALLY ADHERES TO AREAS OF SAID LAYER WHEREIN CHARGED AN DISCHARGED AREAS MEET, SUCH AREAS EXHIBITING AN ELECTRIC FIELD GRADIENT, THEREAFTER, DEVELOPING SAID ELECTROSTATIC LATENT IMAGE WITH A SECOND DEVELOPER CONTAINING A COLORED TONER WHICH IS VISIBLE WHEN VIEWED AGAINST THE PHOTO CONDUCTUVVE LAYER BY CONTACTING SAID LAYER WITH SAID SECOND DEVELOPER, SAID TONER HAVING THE SAME POLARITY AS THAT OF THE CHARGED AREAS ON THE PHOTOCONDUCTIVE LAYER SIMULTANEOUSLY ESTABLISHING A POTENTIAL BETWEEN SAID SECOND DEVELOPER AND THE PHOTOCONDUCTIVE LAYER THEREBY DEPOSITING THE COLOR TONER IN THE DISCHARGED AREAS OF SAID LAYER FORMING A REVERSAL IMAGE OF THE ORIGINAL IMAGE PATTERN.
Claim 3
Dependent Claim 19 words
Process as defined in claim 1 wherein a potential is established between said first developer and the photoconductive layer.
Claim 4
Dependent Claim 25 words
Process as defined in claim 1 wherein said substantially invisible toner of the first developer comprises colorless, light-colored or white polymers, pigments or mixtures thereof.
Claim 5
Dependent Claim 14 words
Process as defined in claim 1 wherein the photoconductive insulating layer comprises amorphous selenium.
Claim 6
Dependent Claim 19 words
Process as defined in claim 1 wherein the photoconductive insulating layer comprises zinc oxide in an insulating resin binder.
Claim 7
Dependent Claim 20 words
Process as defined in claim 1 wherein the colored toner of the second developer contains carbon black as the colorant.
Claim 8
Dependent Claim 25 words
Process as defined in claim 1 wherein the toner of the first developer has the same polarity as the charged areas of the photoconductive layer.
Claim 9
Dependent Claim 27 words
Process as defined in claim 1 wherein the toner of the first developer has the opposite polarity as that of the charged areas of the photoconductive layer.

References Cited (Backward Citations)

US2817598A Cited
US3010842A Cited
US3038799A Cited
US3236776A Cited
US3300410A Cited
US3262806A Cited
US3560203A Cited
US3773507A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1978-08-25 1979-02-24 1979-08-26 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1982-08-25 1983-02-24 1983-08-26 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1986-08-25 1987-02-24 1987-08-26 $7700.00 Window Closed / Lapsed

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