A document (1) carries indicia and at least one copy protection device (2). The copy protection device (2) comprises a marking separate from the indicia and defined by a pair of inks (3; 4-8) which present a continuous, substantially plain coloured area when viewed and illuminated under visible light, the presence of the different inks being substantially undetectable when the area is subjected to visible colour separation scanning. When the area is scanned at and/or illuminated under at least one wavelength outside the visible wavelength range a pattern is generated which is detectable, whereby the presence of this combination of properties indicates that a copying process should not be carried out.
申请公布号
WO9513597(A3)
申请公布日期
1995.09.28
申请号
WO1994GB02503
申请日期
1994.11.14
申请人
THOMAS DE LA RUE AND COMPANY LIMITED;NUTTON, ANDREW;BRATCHLEY, ROBIN;BALDWIN, STANLEY, IVOR;HASLOP, JOHN, M.
发明人
NUTTON, ANDREW;BRATCHLEY, ROBIN;BALDWIN, STANLEY, IVOR;HASLOP, JOHN, M.