Copy-Protected documents

The invention relates to documents of value incorporating features that prevent them being accurately copied by image reproduction means such as a scanner or photocopier. A document of value (10) bears an image comprising a material comprising a TPP (tetraphenyl porphine) wherein the image has a fir...

Ausführliche Beschreibung

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Bibliographische Detailangaben
Hauptverfasser:	NEIL MACNAB, GEORGE FERN, ROBERT WITHNALL, JACK SILVER
Format:	Patent
Sprache:	eng
Schlagworte:	ADHESIVES BOOK COVERS BOOKBINDING CHEMICAL PAINT OR INK REMOVERS CHEMISTRY COATING COMPOSITIONS, e.g. PAINTS, VARNISHES ORLACQUERS CORRECTING FLUIDS DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDEDFOR DYES FILES FILLING PASTES INKS LOOSE LEAVES MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FORELSEWHERE METALLURGY MISCELLANEOUS APPLICATIONS OF MATERIALS MISCELLANEOUS COMPOSITIONS MOVABLE-STRIP WRITING OR READING APPARATUS NATURAL RESINS PAINTS PASTES OR SOLIDS FOR COLOURING OR PRINTING PERFORMING OPERATIONS POLISHES PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITYFEATURES PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOTOTHERWISE PROVIDED FOR SPECIAL PRINTED MATTER TRANSPORTING USE OF MATERIALS THEREFOR WOODSTAINS
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Beschreibung
Zusammenfassung:	The invention relates to documents of value incorporating features that prevent them being accurately copied by image reproduction means such as a scanner or photocopier. A document of value (10) bears an image comprising a material comprising a TPP (tetraphenyl porphine) wherein the image has a first appearance under daylight and has a second appearance under synthetic white light. A copy (14) of the original document (10) is not colour identical to the original document. One example of such TPP exhibits a change from a yellow/green colour in visible light to yellow when scanned on a fluorescent scanner, and a change from yellow/green to almost white when reproduction is attempted on an LED scanner. An appropriate printing ink is also disclosed.