Printed matter – Having revealable concealed information – fraud preventer or... – Utilizing electromagnetic radiation
Patent
1991-03-29
1992-12-15
Echols, P. W.
Printed matter
Having revealable concealed information, fraud preventer or...
Utilizing electromagnetic radiation
283 74, 283 85, 283 58, 283902, 428916, B42D 1500
Patent
active
051710404
ABSTRACT:
The text discloses for use in printing valuable documents an allover pattern of warning indicia which is merged by human sensory perception with its background but is distinguished and reproduced by xerographic copying as a result of the employment of two different screen values for the indicia and the background which are respectively within and beyond the reproductive capability of the copier machine when used in the stated context. Adjunctively, document validating indicia are also printable on such documents in a screen value beyond the reproductive capability of xerographic copiers at the lighter settings at which the lesser screen value used for said warning indicia or background will reproduce.
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The Lithographers Manual, 8th Ed., 1988, Graphic Arts Technical Foundation, Inc., Chapter 11, "Platemaking", p. 9.
Research Project Report, 1965 (reprinted 1987), Graphic Arts Technical Foundation, Inc., "The GATF Dot Gain Scale" by Frank Preucil, Zenon Elyjiw and Robert F. Reed.
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Bryant David P.
Echols P. W.
Invisible Images, Inc.
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