Patent Grant
10889140
This application is the U.S. national phase of International Application No. PCT/EP2018/056054 filed Mar. 12, 2018 which designated the U.S. and claims priority to EP Patent Application No. 17170921.5 filed May 12, 2017, the entire contents of each of which are hereby incorporated by reference.
The present invention generally relates to a security element or document, such as a banknote, and a process of producing the same. More precisely, the invention relates to such a security element or document that comprises a substrate with first and second sides and exhibiting at least one window region made of a substantially transparent material, a micro-optical structure provided on the first side of the substrate and extending over at least a part of the window region, and a printed feature printed on the second side of the substrate over at least a part of the window region, the printed feature being provided in register with the micro-optical structure to produce an optically-variable effect upon looking at the printed feature from the first side of the substrate through the micro-optical structure and the window region.
Such a security element or document is already known in the art, for instance from International Publication No. WO 94/27254 A1.
International Publication No. WO 94/27254 A1 especially discloses such a security element and document (see in particular the illustration of FIG. 5 of WO 94/27254 A1) where the optically-variable effect is based on the so-called “moiré magnification” principle, a well-known principle relying upon the interaction between an array of e.g. micro-lenses overlaid onto a corresponding array of micro-images, which arrays are provided one with respect to the other with a slight pitch mismatch (especially a slight angular misalignment between the two arrays), leading to magnified replication of the micro-images when looking at the device from the side where the micro-lenses are provided. The underlying principle of such a device is for instance disclosed in “The moiré magnifier”, M. C. Hutley, R. Hunt, R. F. Stevens and P. Savander, Pure and Applied Optics, Journal of the European Optical Society Part A 3, pp. 133-142 (1994), and in the “Properties of moiré magnifiers”, H. Kamal, R. Völkel and J. Alda, Optical Engineering 37 (11), pp. 3007-3014 (November 1998).
Such security elements or documents can also rely on an interlacing of different images (or frames) along one or two directions, as disclosed for instance in U.S. Pat. Nos. 4,892,336, 9,132,690 B2 and 9,383,588 B2 and International Publication No. WO 2007/020048 A2.
A problem with the solution disclosed in FIG. 5 of International Publication No. WO 94/27254 A1 in particular resides in that the printed feature that is printed in the window region is visible and exposed on the second side of the substrate, and only contributes to the creation of the optically-variable effect when seen from the first side of the substrate, through the micro-optical structure and window region. The printed feature is therefore prone to substantial degradation during the life-cycle of the security document, which inherently affects and deteriorates the quality of the desired effect. In practice, this has therefore led the man skilled in the art to integrate the security element per se as a security thread or a transfer element that is only exposed on the side where the micro-optical structure is provided. One illustrative example thereof is for instance the US $100 note that entered circulation in 2013 and exhibits a so-called “Motion” thread embedded in the substrate as a one-sided windowed thread that is only visible from the front side of the note, next to the portrait of President Benjamin Franklin. This avenue however restricts the freedom of the security designer and printer as the security element is not anymore producible at the printing works, but either has to be embedded in the substrate material during production thereof (like in the case of the aforementioned US $100 note) or has to be supplied as a high-cost consumable, such as a transfer element that is applied on one side of the substrate by e.g. hot-stamping techniques.
Coming back to the solution disclosed in FIG. 5 of International Publication No. WO 94/27254 A1, a further problem resides in that image contrast of the resulting optically-variable effect is poor as the optical effect is observed through a substantially-transparent medium, the only contrasting elements being created by the printed feature that is printed in the window region on the second side of the substrate. It is in particular difficult to clearly discriminate and distinguish the optically-variable effect as the image contrast depends on the relevant background against which the security element or document is held by the observer, as well as the relevant lighting conditions.
An improved solution is thus required.
International Publication No. WO 2008/031170 A1 discloses a security document comprising a substrate including at least one region of transparent or translucent plastics material forming a window or halfwindow area, and a security device integrated into the window or half-window area, wherein the security device is formed from an embossed radiation curable ink, the security device including one or more of a diffractive structure, a lens structure or other security element having an embossed relief structure.
The publication DE 10 2010 019 766 A1 discloses a method for producing a microstructure on a carrier by: (a) manufacturing a donor foil by forming an embossed structure with elevations and depressions in a first foil material and applying a transfer layer to the embossed structure, (b) manufacturing an acceptor foil by applying an adhesive layer to a second foil material, (c) laminating the donor foil and the acceptor foil by means of the adhesive layer, the transfer layer on the elevations of the embossed structure bonding to the adhesive layer, and (d) transferring the bonded regions of the transfer layer to the acceptor foil by separating the donor foil and the acceptor foil from each other, thereby forming in the acceptor foil a first microstructure from the transferred regions of the transfer layer, and/or forming in the donor foil a second microstructure complementary to the first microstructure.
The publication GB 2 514 030 A discloses a three-dimensional security element and an injection-molded product having the three-dimensional security element, wherein the three-dimensional security element further comprises: a micro lens array to which various types of lenses can be applied; an image array; a primer layer for facilitating adhesion; and a protection film for protecting the three-dimensional security element from heat and pressure.
A general aim of the invention is therefore to provide an improved solution, namely such a security element or document where the optically-variable effect exhibits and maintains a better quality and image contrast over its life-cycle.
A further aim of the invention is to provide such a solution that provides greater freedom to the security designer and printer in terms of design opportunities and printing possibilities, and improves printability of the substrate on the side opposite to the side where the micro-optical structure is provided.
Yet another aim of the invention is to provide such a solution that is more easily producible at the printing works and that does not rely upon the use of high-cost consumables.
These aims are achieved thanks to the solutions defined in the claims.
In accordance with the invention, there is provided a security element or document, such as a banknote, comprising a substrate with first and second sides and exhibiting at least one window region made of a substantially transparent material, a micro-optical structure (provided on the first side of the substrate and extending over at least a part of the window region, and a printed feature printed on the second side of the substrate over at least a part of the window region, the printed feature being provided in register with the micro-optical structure to produce an optically-variable effect upon looking at the printed feature from the first side of the substrate through the micro-optical structure and the window region. According to the invention, the security element or document further comprises a protective layer acting as printable primer layer and provided on the second side of the substrate over the window region and on top of the printed feature, which protective layer covers the printed feature when seen from the second side of the substrate and further acts as a contrast-enhancing layer for the optically-variable effect.
Preferably, the micro-optical structure consists of an array of micro-lenses, especially hemicylindrical or hemispherical micro-lenses.
The micro-optical structure can advantageously be provided onto the window region, preferably by hot-stamping, in the form of a foil carrying the micro-optical structure, or be formed directly onto the window region, especially by embossing or casting.
The printed feature is a multicolour feature printed by Simultan offset printing, which printing process is only used in the context of the production of security documents, such as banknotes.
In accordance with an embodiment of the invention, the protective layer is overprinted on top of the printed feature by screen printing, which allows achieving a good and uniform coverage of the window region and printed feature, and leads to optimum printability of the relevant portion on the second side of the substrate. Screen printing is typically used in printing works and is therefore readily available to apply the required protective layer. In this context, the protective layer has a substantially uniform colour appearance that closely matches that of an unprinted surface of the substrate, especially a white appearance. Tests carried out by the Applicant have furthermore demonstrated that the best results are achieved if use is made of a UV-cured material to print the protective layer.
In accordance with a possible refinement of the invention, a functional layer could furthermore be interposed between the printed feature and the protective layer. Such functional layer could in particular be a mirror-effect layer or an optically-responsive layer that produces an optical response when subjected to an illumination stimulus outside of the visible spectrum, such as UV light.
Preferably, the substrate is selected from the group of substrates consisting of:
Advantageously, the security element or document further comprises a printed pattern that is printed on top of the protective layer, especially by intaglio printing.
There is also provided a process of producing a security element or document, such as a banknote, comprising the following steps:
The step of providing the micro-optical structure and the step of printing the printed feature are carried out in one and a same operation. This is achievable thanks in particular to a combined casting and printing platform as for instance disclosed in European Patent Application No. 17157503.8 of Feb. 22, 2017 and European Patent Application No. 17167792.5 of Apr. 24, 2017 both in the name of the instant Applicant and entitled “PRINTING PRESS WITH IN-LINE CASTING DEVICE FOR THE REPLICATION AND FORMATION OF A MICRO-OPTICAL STRUCTURE”
Further advantageous embodiments of the invention form the subject-matter of the dependent claims and are discussed below.
Other features and advantages of the present invention will appear more clearly from reading the following detailed description of embodiments of the invention which are presented solely by way of non-restrictive examples and illustrated by the attached drawings in which:
The present invention will be described in the particular context of an application to a banknote. It is however to be appreciated that the invention is applicable to the production of any security element or document, including for instance passports and like ID documents or other types of value or security document. Furthermore, while the illustrations of
Within the scope of the present invention, the expression “window region” designates any substantially transparent or translucent region formed in the relevant substrate material and that is, at least initially (i.e. before application of the relevant printed feature and protective layer), visible from both sides of the substrate. The invention is not limited to any particular configuration, shape and dimensions of the relevant window region. In particular, one or more window regions could be provided.
As regards the substrate, any suitable substrate material convenient for the production of the desired security element or document could be used. This preferably includes any substrate selected from the group of substrates consisting of:
The following embodiments will be discussed in the particular context of a substrate in accordance with (ii) above. As schematically illustrated in
In accordance with the invention, and as illustrated schematically in
The window region W shown in
In accordance with the invention, a printed feature is printed on the second side II of the substrate S over at least a part of the window region W. As shown in the illustrative example of
More precisely, in the illustrated example, the printed feature P1-P3 comprises a series of printed elements P1, P2, P3 that are structured to ultimately create corresponding optically-variable effects, when combined with an associated micro-optical structure provided on the first side I of the substrate S (which micro-optical structure is not shown in
As a matter of fact, any desired design could be printed in the window region W on the second side II of the substrate S and it will be appreciated that the security designer is basically free to design and combine various printed elements in different ways to create the desired printed feature, which highlights the considerable advantage of the present invention over the known solutions that rely upon the use of a security thread or security device that is embedded in or applied on the substrate as the relevant security element.
The printed feature is a multicolour feature that is printed by Simultan offset printing, which printing process is already used in the art of security printing. Simultan offset printing relies upon the use of a specific offset printing press (such as the Super Simultan® IV or Super Orlof Simultan® printing presses marketed by the present Applicant) where multiple ink patterns are collected on a common blanket cylinder before transfer onto the substrate. Simultan offset printing presses are known as such in the art, in particular from European Patent Publication No. EP 0 949 069 A1, International Publications Nos. WO 2007/042919 A2, WO 2015/032515 A1, WO 2016/042482 A2 or even European Patent Application No. 17160749.2 of Mar. 14, 2017 in the name of the Applicant entitled “SHEET-FED PRINTING PRESS FOR SIMULTANEOUS RECTO-VERSO PRINTING OF SHEETS, IN PARTICULAR FOR THE PRODUCTION OF SECURITY DOCUMENTS”.
While this is not specifically illustrated in
In accordance with the present invention, and as illustrated by
A first function fulfilled by the protective layer L is to act as a printable primer layer, namely a layer that provides adequate basis for the subsequent provision of additional printed patterns. In that respect, the protective layer is overprinted on top of the printed feature P1-P3 by screen printing. Screen printing is known as such in the art and relies upon the use of a specific screen printing press as for instance marketed by the Applicant under the product designation Nota Screen®. Such a screen printing press is known for instance from European Patent Publication No. EP 0 723 864 A1 and International Publications Nos. WO 97/34767 A1, WO 2009/022317 A1 and WO 2016/102187 A1.
A considerable advantage of screen printing resides in the fact that a substantially uniform layer can be printed on the second side II of the substrate S so as to optimally act as the desired protective layer L. Screen-printed layers in particular exhibit a very good coverage, thereby efficiently acting as protective layer for the underlying printed feature P1-P3.
Furthermore, tests carried out by the Applicant have demonstrated that the use of a UV-cured material (especially a UV-curable screen printing ink) is particularly efficient in creating a very resistant protective layer L that guarantees optimal resistance to wear and tear over the life-cycle of the security element or document.
In accordance with the embodiment of the invention, the protective layer L is selected to have a substantially uniform colour appearance that closely matches that of the unprinted surface of the relevant substrate S. In this context, the protective layer L can in particular be selected to exhibit a substantially white appearance, especially such a white appearance that matches that of the aforementioned opacifying layers 11, 12.
In accordance with the invention, a further function fulfilled by the protective layer L is to act as a contrast-enhancing layer. Indeed, the protective layer L provides a well-defined surface that acts as background layer for the printed feature P1-P3 when seen from the other side of the substrate S, namely from the first side I. As schematically illustrated by
It will once again be appreciated that the application of the protective layer L by by screen printing likewise opens up possibilities for the security designer to shape and structure the protective layer L in any desired way. In particular, the protective layer L could be designed so as to be fully integrated in the final design of the reverse side II of the banknote BN. By way of preference, the printed pattern P and protective layer L on the second side II of the substrate S jointly form the background design of the reverse side II of the banknote BN.
In accordance with the present invention, and as further illustrated by
The micro-optical structure OP could be provided in various ways. It could for instance be provided on the window region W during or subsequent to the production of the substrate S, especially by embossing or casting. In accordance with a particularly advantageous embodiment, the provision of the micro-optical structure OP on the first side I of the substrate S could take place by casting simultaneously with the printing of the printed feature P1-P3 on the second side II of the substrate S. This is feasible thanks to a combined casting and printing platform as for instance disclosed in European Patent Application No. 17157503.8 of Feb. 22, 2017 and European Patent Application No. 17167792.5 of Apr. 24, 2017 both in the name of the instant Applicant and entitled “PRINTING PRESS WITH IN-LINE CASTING DEVICE FOR THE REPLICATION AND FORMATION OF A MICRO-OPTICAL STRUCTURE”, the content of which applications is incorporated herein by reference in its entirety.
In the example of
This once again provides great freedom with respect to the production of the security element or document of the invention, in that the printer has the liberty to produce the necessary micro-optical structure OP directly at the printing works if desired.
It will be appreciated that the micro-optical structure can be formed at any appropriate stage of the production, whether before, during or after printing of the associated printed feature with which the micro-optical structure is to be combined. Key is that the micro-optical structure and associated printed features are provided on the first and second sides of the substrate in register with one another.
Preferably, the micro-optical structure OP consists of an array of micro-lenses, especially hemicylindrical or hemispherical micro-lenses. Other micro-optical structures are however possible, depending on the optically-variable effect that one wishes to ultimately generate.
As a result of the combination of the micro-optical structure OP and the printed feature P1-P3, an optically-variable effect EF is produced, which optically-variable effect EF changes in dependence of the viewpoint from which the optically-variable effect EF is observed.
As further depicted in
A refinement of the present invention may consist is further providing a functional layer FL between the printed feature P and the protective layer L. Such functional layer may in particular be a mirror-effect layer or an optically-responsive layer that produces an optical response when subjected to an illumination stimulus outside of the visible spectrum, especially UV light.
Various modifications and/or improvements may be made to the above-described embodiments without departing from the scope of the invention as defined by the annexed claims. For instance, as already mentioned, the micro-optical structure is provided on the first side of the substrate during printing of the printed feature. Providing the micro-optical structure and printing the printed feature in one and a same operation has the advantage that register between the two components of the security element or document can be precisely controlled.
| Number | Date | Country | Kind |
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| PCT/EP2018/056054 | 3/12/2018 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
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| WO2018/206180 | 11/15/2018 | WO | A |
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| Number | Date | Country | |
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| 20200384792 A1 | Dec 2020 | US |
