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Copy preventing device and method

  • US 5,301,981 A
  • Filed: 10/29/1992
  • Issued: 04/12/1994
  • Est. Priority Date: 07/09/1992
  • Status: Expired due to Fees
First Claim
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1. A copy preventing sheet-form screen comprising a lenticular screen formed by a sheet of transparent material having front and rear faces and a series of adjacent lens portions with major optical axes perpendicular to the front face and a series of light blocking striae located spaced apart underlying respective lens portions and extending across a major part of their major optical axes so that positioning the copy preventing sheet-form screen with the rear face in covering relation to a sheet carrying indicia providing meaningful information, enables the information to be easily seen when viewed obliquely in ambient white light bu prevents a meaningful copy thereof being made by conventional, perpendicularly aligned, phototransference techniques including at least one of xerographic, offset printing, and facsimile.

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