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US4738901A Expired / Lapsed US ⏱️ 0.0 years remaining

Method and apparatus for the prevention of unauthorized copying of documents

Assignee: Xerox Corp
•
Filing: 1987-03-27
•
Granted: 1988-04-19
•
Expires: 2007-03-27
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Abstract

Abstract Method and apparatus are disclosed for the prevention of unauthorized copying of documentation on an office, or other type, copier. Unique phosphors are applied to paper. When such a paper is placed on or in a copier so prepared, the presence of the phosphor is detected and the copier is disabled. Inside the copier a laser emits a beam toward the paper. Two detectors detect, respectively, the laser light reflected from the document and the stimulated light from the phosphor coating or layer. Detection of both signals, in the proper time sequence, will cause the photocopier to cease operation prior to electrostatic or other capture of the image. Upconversion phosphors could be utilized as the phosphor coating due to their scarcity and unliklihood of use in this manner.

Inventors

  • 👤 Joel R. Finkel
  • 👤 Paul F. Jacobs
  • 👤 Kenneth I. Gustafson
  • 👤 William D. Green

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-26 23:17
CPC Classifications
G; G03; G03G; G03G21/00; G03G21/04; G03G21/046; Y; Y10; Y10T; Y10T428/00; Y10T428/31504; Y10T428/31971; Y10T428/31993

Claims Analysis

Total Claims: 2
Claim 1
Independent Claim 68 words
A document stock for use in preventing the copying thereof in an office copier or the like comprising: a standard paper substrate, and phosphorescent material on or in said paper substrate, said phosphorescent material emitting radiant energy upon being stimulated by a separate beam of light, wherein said layer of phosphorescent material is an upconversion phosphor which emits light of a higher energy level than that exciting it.
Claim 2
Dependent Claim 68 words
A document stock for use in preventing the copying thereof in an office copier or the like comprising: a standard paper substrate, and phosphorescent material on or in said paper substrate, said phosphorescent material emitting radiant energy upon being stimulated by a separate beam of light, wherein said layer of phosphorescent material is an upconversion phosphor which emits light of a higher energy level than that exciting it.

References Cited (Backward Citations)

US2822288A Cited
US4442170A Cited
US4451530A Cited
US4451521A Cited
US4452843A Cited
JPS5888700A Cited
JPS5952689A Cited
US4627997A Cited
US4627642A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1991-04-19 1991-10-19 1992-04-19 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1995-04-19 1995-10-19 1996-04-19 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1999-04-19 1999-10-19 2000-04-19 $7700.00 Window Closed / Lapsed

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