Printed matter – Having revealable concealed information – fraud preventer or... – Utilizing electromagnetic radiation
Patent
1998-12-22
2000-07-18
Pitts, Andrea L.
Printed matter
Having revealable concealed information, fraud preventer or...
Utilizing electromagnetic radiation
283 72, 283 73, 283 85, 283 87, 283 91, 283 94, 283 99, 283109, 283113, 283114, 283117, 283901, 428 29, 428 30, 428209, B42D 1500, B32B 900
Patent
active
060896140
DESCRIPTION:
BRIEF SUMMARY
The invention relates to security devices, particularly for use with documents of value.
In the field of security documents, such as banknotes and the like, there is a continuing need to incorporate security devices which prevent such security documents from being counterfeited using the increasingly sophisticated commercial printing equipment which is available.
Examples of security devices which have been used in the past include complex patterns printed on the document, optical devices such as diffraction gratings and holograms and the like.
For certain translucent papers a security feature which involves providing (usually printing) an image on both sides of the paper was developed many years ago. In one form, herein defined as a "see-through" feature, complementary images are provided on each side of the sheet precisely registered relative to one another such that when the sheet is held up to the light, the image on the back will fit exactly into spaces within the image on the front, optionally with an even unprinted margin around the perimeter. For example, each image could comprise a series of coloured segments, segments on one side of the sheet fitting within the spaces between the segments on the other. Printing of these images is normally carried out with specialised lithographic presses which allow simultaneous front and back printing during one printing run. In this way, the tolerances applied to the design elements are typically a fraction of a millimeter and any variation caused by counterfeiting by printing both sides during different printing runs can be quickly noticed. By printing on both sides in a single impression, misregister due to variations in the dimensions of the sheet caused by change of moisture content or heating and the like are avoided. See-through features have four nodes of visual inspection--the first image viewed in reflected light, the image on the other side of the sheet viewed in reflected light, the composite image viewed by transmitted light as viewed from the first side and with the image on that side predominating, and finally the composite image as viewed on the other side of the sheet with the image on that side predominating, on transmissive viewing of see-through features the image on the opposite side of the sheet is seen to be in register in a genuine document.
An example of see-through features used with banknotes and the like is described in EP-A-0388090 in which the feature is provided in a region of the sheet which has a substantially uniform transparency which is more transparent than a majority of the remainder of the sheet in the absence of applied ink.
DE-A-3208004 describes the use of periodic lineal point patterns on opposite sides of a sheet which, when viewed in transmission, produce a characteristic moire pattern indicating that the sheet is genuine.
GB-A-2282563 illustrates the use of apparently random patterns of dots at opposite sides of the sheet which, when viewed in transmission, generate a recognizable pattern.
EP-A-0628408 relates to the inclusion of a printed layer, laminated between two paper sheets, the print only being visible in transmitted light. The image may be registered to an image on one of the outer layers in a cooperative way so as to form a complete image.
EP-A-0755799 relates to a letterpress printing technique that autoregisters a fluorescent image on one side of a document to a letterpress image on the other side.
WO 94/29119 describes an embossed structure that is designed to give a switching effect across a transparent zone. The effect is due to light being reflected as a consequence of the angle of incidence either exceeding or not exceeding the critical angle as a consequence of the embossed surface. This results in light either being reflected off the surface or being allowed to pass through. The effect is obtained when the embossed pattern on the front side exactly coincides with the reverse side pattern.
U.S. Pat. No. 4,307,899 describes a process for creating watermark effects on cards rather than paper. In this
REFERENCES:
patent: 5851032 (1998-12-01), Green
patent: 5855989 (1999-01-01), Mantegazza
Drinkwater Kenneth John
Holmes Brian William
Howland Paul
De La Rue International Limited
Henderson Mark T.
Pitts Andrea L.
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