Printed matter – Having revealable concealed information – fraud preventer or... – Utilizing electromagnetic radiation
Reexamination Certificate
2000-06-22
2002-12-17
Fridie, Jr., William (Department: 3722)
Printed matter
Having revealable concealed information, fraud preventer or...
Utilizing electromagnetic radiation
C283S067000, C283S070000, C101S211000
Reexamination Certificate
active
06494490
ABSTRACT:
FIELD OF THE INVENTION
The invention concerns a process for producing any photoluminescent printed polychromatic image (namely one which can incorporate all the shades of colours and various forms possibly including continuous variations of colours (shaded, fading etc., shadows, intensity variations, mottled effects etc.) invisible under illumination with visible light and visible under illumination by at least one source of invisible light, designated hereinafter in all the text as “any photoluminescent printed polychromatic image”.
“Visible light” designates a light of which the spectral composition is situated in the visible spectrum from 0.4&mgr; to 0.8&mgr;. “Invisible light” designates a light of which the spectral composition is situated outside the visible spectrum, in particular in the ultra violet and/or the infra red spectrum.
BACKGROUND OF THE INVENTION
Photoluminescent printed monochromatic markings which are invisible under illumination with visible light and visible under illumination with invisible light (ultraviolet or infra red) are often used for the purpose of the authentication of documents such as bank notes. Different printed monochromatic markings may be juxtaposed and/or superimposed, which create spots of colours composed of a finite number and in a discontinuous manner.
Nevertheless, these photoluminescent monochromatic markings do not make it possible to produce a true photoluminescent printed polychromatic image reproducing, with all the shades of colours and forms, any polychromatic image visible in visible light such as a photographic image which is not in half-tone and is non-digitized.
Any photoluminescent printed polychromatic image of this type may be of value in many fields and may have various applications, in particular as an authentication element and/or for the purposes of decoration.
As regards authentication, any photoluminescent printed polychromatic image may provide at least three levels of authentication: printing the image creates raised patterns and/or an opalescence visible in visible light; under illumination in invisible light, it is possible to verify the conformity of the image which is extremely difficult to counterfeit perfectly taking into account its complexity and the fact that it is applied to the background of a document provided with other designs visible by transparency, unless the original is available which is visible under visible light, reproduction from the image visible in invisible light not providing the original image; and spectrophotometric analysis enables the photoluminescent compounds used to be identified and therefore their authentic character.
For decorative purposes, any photoluminescent printed polychromatic image of this type proves to have a an unusual special appearance when illuminated in invisible light.
However, various attempts to produce a photoluminescent printed polychromatic image of this type which date back more than sixty years have ended in failure.
In particular, traditional printed polychromatic images visible in visible light are generally produced in quadrichrome (yellow, magenta, cyan, black) on a white background. The original image is filtered with three coloured filters (blue, green, red) having a spectral pass-band of 100&mgr; (a third of the visible spectrum). The appearance of colours on the printed image is due to the reflection of natural visible light (daylight or an illuminating lamp) by the printed substrate through the transparent coloured inks which selectively absorb the incident light according to the so-called “material colour” principle by subtractive synthesis. For each coloured ink, the substrate reflects two thirds of the visible spectrum, according to a complementary spectral composition of the absorption spectrum of the ink in the visible region. With this technique, it is not possible to produce a photoluminescent printed polychromatic image. Indeed, if photoluminescent pigments are used corresponding to the fundamental colours of the coloured filters used for printing in quadrichrome, in inks which are printed from three negatives obtained after filtering with the aid of traditional coloured filters, it is not possible in practice to reproduce the polychromatic image in a photoluminescent manner, reliably and with good quality.
THE KNOWN PRIOR ART
U.S. Pat. Nos. 2,302,645, 2,277,169 and 2,434,019 thus describe various attempts to produce images with the aid of fluorescent pigments.
Nevertheless, the processes described in these documents do not make it possible to produce a photoluminescent printed polychromatic image by automatic and reliable reproduction of a polychromatic image. Indeed, the processes described in these documents consist of manually producing, in the first instance, a trichromatic positive. Subsequently, this trichromatic positive is used to be reproduced by printing with the aid of inks, certain of which incorporate fluorescent pigments. As a consequence, these documents show that the automatic obtaining of a trichromatic photoluminescent positive has been abandoned, since these documents consider that the positive is out of necessity produced manually.
Equally, the document R. J. TUITE “Fluorescent multicolor additive system” XP 002108747, PRODUCT LICENSING INDEX, no84, pages 81-85, INDUSTRIAL OPPORTUNITIES LTD, HAVANT, GB ISSN: 0374-4353, April Issue, 1971, teaches the production, by printing with the aid of a gravure plate press, of a multicoloured image which is fluorescent under ultraviolet light. The process used in this document consists of producing negatives with red, green and blue separation from a continuous positive by exposure through a red, green and blue filter, respectively. With this process, since each of the negatives has not been finely filtered, the largest proportion of the area of the final image includes an abnormal surcharge of the three colours forming a dominant white. On account of this, the fluorescent image obtained is extremely pale and is in practice either invisible or a “phantom” image, in spite of the production of a large number of successive final layers of green ink.
OBJECTS OF THE INVENTION
The object of the invention is therefore in a general manner to enable any photoluminescent printed polychromatic image to be produced. Accordingly, the object of the invention is to make it possible to reproduce in a printed photoluminescent form and in an automatic and reliable manner, any original polychromatic photographic image formed by subtractive synthesis (material colour principle) and which is visible in visible light (printed, painted, photographic image etc).
The invention also aims at providing a simple and low-cost process for rapidly obtaining and reproducing such an image on the industrial scale, automatically and reliably, in particular in a manner similar to traditional printing techniques, without requiring the manual production of a trichromic positive by an artist, and while providing a high quality and high contrast image.
The invention also aims at providing applications for any kind of photoluminescent printed polychromatic image.
SUMMARY OF THE INVENTION
To this end, the invention concerns a process for producing any photoluminescent printed polychromatic image invisible under illumination in visible light and visible under illumination by at least one source of invisible light, wherein:
an original polychromatic image
1
, visible in visible light, is chosen or is produced by subtractive synthesis (material colour principle),
at least one set of at least three images, known as filtered images, is produced and recorded by filtering the original image,
at least one set of at least three images, known as printed images, is printed separately one after the other and one above the other, by using and reproducing respectively one of the filtered images, with a printing composition containing a photoluminescent pigment, the different photoluminescent pigments of the different printed images of the same set emitting, under illumination by at least one source of invisible light, colours capa
Fridie, Jr. William
Young & Thompson
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