FR3045907B1 - SECURITY ELEMENT HAVING HIDDEN INFORMATION, DOCUMENT-VALUE THAT INCLUDES IT AND DEVICE FOR VERIFYING THIS HIDDEN INFORMATION - Google Patents

Abstract

The present invention relates in particular to a security element which comprises a support (1) on which is present at least one impression (2; 2 '; 2 "; 3), characterized in that: - it comprises a first print (2) invisible to visible light, but revealed under a first wavelength range (λ1) outside the visible light spectrum, and a second print (3) invisible to visible light, but revealed in a second wavelength range (λ2) out of the visible light spectrum; - said first and second impressions (2, 3) extend into partially overlapping regions, thereby constituting at least one zone at least one overlap zone (4) constitutes at least one hidden information (IC) which is revealed under a stroboscopic illumination alternating illumination under two ranges of wavelengths which respectively correspond to said first and second ranges of wavelengths (λ1 and λ2).

Description

FIELD OF THE INVENTION

The present invention relates to a security element. It also relates to a document-value that includes at least one such element, as well as a device for verifying the information hidden within such an element.

BACKGROUND OF THE INVENTION

The present invention applies more particularly to a security element for a document-value such as, for example, a fiduciary document or similar.

The term fiduciary document means all documents such as bank notes, checks, bank cards or other media used to transmit a sum of money.

By assimilated document, we mean all documents issued by a State administration to attest to the identity of a person, or his rights to drive a vehicle, such as an identity card, a passport or driver's license.

This expression also refers to any type of document used to authenticate an object of value, such as, for example, a label to put on a garment. We also hear any document used to authenticate the payment of a tax, such as tax stamps.

In such a field, and more particularly for banknotes, it is known to affix one or more security elements of various natures, to protect these documents from possible fraudulent manufacture.

Thus, there are different types of security elements responding to a classification by level and the present invention relates to a so-called second level security element, that is to say whose authentication requires a tool, for example an ultraviolet lamp, namely a commonly used tool and whose use is generally understood by the general public.

It is known to those skilled in the art EP1567358 which describes a safety device comprising at least two regions containing materials in which the two or more regions have substantially the same color visible in first observation conditions comprising light visible and different colors visible in second observation conditions which are a combination of visible light and a light of substantially any UV wavelength in the range of 235 to 380 nm.

If the security element is simple to implement, it is however threatened by the increasing availability to the general public of legal solutions for inkjet printing ink or fluorescent toners (inks powder) ( in the range described above, that is to say 235 to 380 nm), or even illicit solutions using materials sold by sites hosted on the Darknet for example.

In the document EP1719637, it is questioned, in order to reinforce the safety measures based on fluorescent materials, to use a transparent window extending through the document under consideration, a transparent UV blocking layer in the region defined by the transparent window. and a first fluorescent ink pattern printed between the UV blocking layer and the transparent window.

Thus, the pattern is invisible normally but becomes visible on both sides if it is illuminated with UV from the side of the window. It remains invisible when illuminated on the side of the UV blocking layer.

Of course, with a combination of fluorescent inks of different colors ideally arranged on both sides of the UV blocking layer, it is possible to obtain complex effects that make counterfeiting more complicated.

But the disadvantage of this solution is that it is necessary to integrate a transparent window into a paper document, or to adopt a polymeric support and add materials to form a UV blocking layer. This inevitably has an impact on the manufacturing complexity of the media and their cost.

In the document WO 2014 177375, there is a question of a security element composed of at least three layers each comprising a different material, of which the first, the second and the third materials are capable of interacting with each other with a first, second and second and third electromagnetic radiations, all composing an animated pattern by sequential illumination capable of emitting precisely separately into each of the individual radiations exciting one of the particular materials.

Here we find the principle of the cinematograph with a pattern that will seem to come alive when the series of illuminants will light. One quickly perceives the limitations of such a system for economic reasons where the number of images of the motive in action allowing the fluidity of the movement will be kept very low to decrease the inflation of the number of inks to print and, concomitantly, the number of different illuminants in the device used to authenticate the security.

Ultraviolet (UV) reactive inks are also more conventionally known which, under the action of a lamp with wavelengths less than 400 nm, emit a luminescent signal in the visible range (400-780 nm). These inks are a common example of second-level security.

Some pigments or ink dyes are also known to absorb at specific wavelengths. They require a lamp emitting on the chosen wavelength.

By wavelength chosen, it is known to recover the wavelengths 365 nm, 312 nm and 254 nm.

However, the pigments or the luminescent dyes of these inks have the main defect of absorbing ultraviolet radiation over broad spectra with higher or lower intensities.

In addition, ultraviolet lamps composed of fluorescent tubes emit on broadband spectra. This facilitates the work of counterfeiters who, with standard ultraviolet lamps, can visualize areas designed for second-level fluorescence color authentication. They can therefore falsify documents using commercial type inks as mentioned above.

However, there are luminescent materials whose absorption peak is targeted to a narrower band, as well as ultraviolet illuminants composed of LEDs (Light Emitting Device), which emit only on a spectral band tightened around a length accurate waveforms and also offer increased technical possibilities compared to vacuum tubes usually called neon, in terms of power consumption, ignition / extinction cycles etc.

This feature allows to limit the action of counterfeiters, because it requires specific equipment. However, this equipment remains affordable, thanks to the rise of LEDs which also combine the advantage of a small footprint, allowing the manufacture of miniaturized devices.

Also known are so-called antistoke luminescence materials which, under the action of a laser calibrated at the defined wavelength, emit in the visible.

By defined wavelength is meant a wavelength greater than 780 nm, and more particularly a wavelength at 980 nm.

Such a security element is by nature difficult to achieve, and requires specific equipment to identify it.

There is therefore a definite need to provide security elements that are not visible to the naked eye and visible light, the complexity of which is not found in the materials themselves (pigments, inks or substrates impacting the manufacturing costs). but in the arrangement of the printed patterns and in the use of economic authentication devices, thus rendering any attempt at reproduction vain.

SUMMARY OF THE INVENTION

It is in this context that the present invention provides a security element which comprises a support on which is present at least one print. This element includes a first impression invisible to visible light, but revealed under a first range of wavelengths outside the spectrum of visible light, and a second impression invisible to visible light, but revealed in a second range of wavelengths outside the spectrum of visible light. Said first and second impressions extend into partially overlapping regions, thus constituting at least one overlap area. Said at least one overlap zone constitutes at least one hidden information which is revealed under a stroboscopic illumination alternating illumination under two ranges of wavelengths which respectively correspond to said first and second ranges of wavelengths.

According to other nonlimiting and advantageous features of the invention:

said second wavelength range is different and outside said first wavelength range.

the element comprises at least one other impression invisible to visible light, but revealed in a range of wavelengths outside the spectrum of visible light, this range of wavelengths being different and outside the other ranges wavelength, that this at least one other printing has, together with the other prints, at least one overlapping area, and that said at least one overlapping area constitutes at least one hidden information which is revealed under a a stroboscopic illumination alternating lightings in wavelength ranges corresponding respectively to said first, second and other wavelength ranges;

said hidden information is an image, a number or a number, a text, a code, an impression of relief generated by the brain of an observer or a combination thereof;

all the impressions are present on the same face of said support;

at least one of said impressions is present on one face of said support, while at least one second impression is present on the opposite face;

said first and / or second printing (s) is / are continuous (s), that is to say constitutes (s) a flat;

said first and / or second printing (s) is / are discontinuous, that is to say is (are) constituted (s) of at least two distinct and separate regions which together constitute a frame;

two impressions are discontinuous and consist of several distinct and separate regions, and under stroboscopic illumination, the coverage density of the support by said impressions in said at least one overlap area is substantially lower, ideally by half the coverage density of the support by said impressions, outside the overlap area; and

the two impressions are discontinuous and consist of several distinct and separate regions, and under stroboscopic illumination, the coverage density of the support by said impressions in said at least one overlap zone is substantially greater, ideally twice the coverage density of the support by said impressions, outside the area of recovery.

The invention also relates to a hidden information revelation device within a security element, comprising at least two sources of light emission in at least two ranges of wavelengths outside the spectrum of visible light. each range of wavelengths being different from the other ranges, as well as means which make it possible to alternate the ignition and the extinction of each source so as to generate, for an observer, a stroboscopic effect.

Advantageously, this device affects the shape of a housing whose cover has a through opening for observing said security element and which encloses said resignation sources.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention will appear on reading the following description of preferred embodiments of the invention. This description is made with reference to the appended drawings in which:

- Figures 1 and 2 are top views of a bank note that incorporates the security element according to the invention, Figures 1 showing only the first impression, while Figure 2 shows only the second printing;

- Figure 3 is a longitudinal sectional diagram of the ticket of Figures 1 and 2 showing the partial recovery of prints;

FIG. 4 is a diagram showing the principle implemented to reveal to an observer the information hidden within said impressions;

FIGS. 5 and 6 are top and bottom views, respectively, of a bill which incorporates the security element according to the invention, the impressions being each present on a large face of the bill;

- Figure 7 is a view similar to Figure 3 of this second embodiment;

- Figure 8 is a view similar to Figure 4;

- Figure 9 are top views of three embodiments of first impressions;

FIG. 10 is a view from above of three variants of second impressions which combine with those of FIG. 9 when the strobe illumination is activated;

FIG. 11 is a view from above of the superpositions of the prints of FIGS. 9 and 10 and of the hidden information that they reveal;

FIGS. 12 to 14 are top views of three impressions, while FIG. 15 represents the superposition of the impressions of these three figures, with the hidden information that they reveal;

- Figures 16 to 19 are views similar to Figures 1 to 4 respectively, showing another variant of this embodiment;

- Figures 20 to 23 are views similar to Figures 5 to 8 respectively, showing another variant of this embodiment;

- Figures 24 to 26 respectively show a first impression from above, a cross section of the print and its support, and a second top view with location of the hidden information which conceals a dotted outline for more clarity but indistinguishable in reality;

- Figures 27 to 29 are views similar to Figures 24 to 26 relating to the second printing which cooperates with the first printing of the figures identified above;

FIG. 30 is a view from above of what an observer sees when the two prints of FIGS. 24 and 27 are subjected to stroboscopic lighting;

- Figures 31 and 32 are cross-sectional views of the support that received these two impressions, depending on whether they are present on the same side of the support;

FIGS. 33 and 34 are front views of two impressions which, taken together, provide a stereoscopic effect;

- Finally, Figures 35 and 36 are simplified diagrams, in perspective and in section, of an apparatus that can be used to make visible the hidden information that is an integral part of the security element.

DETAILED DESCRIPTION OF THE INVENTION

Throughout the following description, there will be a security element that includes at least two impressions. In all of these embodiments, these prints are made using inks, for example made in the line, with guilloches, in the form of a numismatic background, etc.

These prints are made using various printing techniques, such as offset, screen printing, intaglio, flexography, letterpress, inkjet or laser etc., without these examples. limiting.

In the context of the invention, a security element printed in offset will be of particular interest. However, this is a simple illustration, the use of offset printing requiring the availability of a register printing means, as will be seen later in the description.

Thus, it is understood in the present application that at least two impressions or two patterns when they are in registration (or register), that is to say with relative positions defined between them, when they are edge to edge (or contiguous), when they are plumb to each other in full, etc., are theoretical terms, valid in figures, plans and layouts, but which actually suffer from minimal placement differences consecutive to their realization on the document-value in question and also on several document-values compared between them. It is, for example, customary to observe placement tolerances between two simultaneous or consecutive printing groups of the order of +/- 0.01 mm at best in offset, whereas tolerances of at least +/- 0.2 mm at worst when the prints are made in two separate passages that are not online.

As will also be detailed below, the prints are made using means such as inks that are invisible to visible light and to the naked eye, but revealed in ranges of wavelength. outside the spectrum of visible light.

Advantageously, these prints are made with an ink reacting for example at a wavelength in the ultraviolet range or else using an ink reacting at a wavelength in the infrared range.

The two prints emit in the visible with a defined hue (identical according to the two prints or different) when exposed to the precise absorption wavelength defined by the luminescent material itself.

When using a wavelength-responsive ink in the ultraviolet range, then the range of wavelengths used will be less than 400 nm, and especially with absorption peaks centered around 365 nm, 312 nm and 254 nm.

When using a wavelength-responsive ink in the infrared range, then one is in a wavelength range greater than 780 nm and in particular with an absorption peak centered at 980 nm.

Thus, with reference to the appended FIGS. 1 to 3, we are dealing here with a banknote 1, the large opposite faces 10 and 11 of which are covered with various impressions and security means known to those skilled in the art and on which we will not return further.

On the front face 10 of this note is present an impression referenced 2 and has two zones referenced A and B.

In this embodiment, the printing 2 has the shape of a square which continues with a point on one of its sides. Zone A has a diamond-shaped outline, while Zone B is the remaining portion.

Referring now to FIG. 2, there is shown, on the same front face 10 of the banknote, only a second printing 3 comprising two zones A 'and C. The zone A' is in register with the zone A of the first printing 2, so that they overlap completely, and has the same shape and the same dimensions as the zone A. On the other hand, the zone C is located on the right side of the zone A ', and is opposite to the zone B. The zone C could have, in an undescribed variant, a different shape and not symmetrical with that of zone B.

Thus, when referring to the section of Figure 3, it is found that the impressions 2 and 3 overlap partially to form a covering area 4 which consists of the superimposed areas A and A '.

As indicated above, the first impression 2 is made using a material invisible to visible light but revealed under a first range of wavelengths λ! outside the spectrum of visible light. As for the second impression 3, it is produced by means of a second ink invisible to visible light and revealed under a second wavelength range outside the spectrum of visible light, this second wavelength range λ ₂ being different and outside the first range of wavelengths.

Given these characteristics, it is understood that, if the ticket is illuminated above its front face 10 by making use of a light of wavelength λ _1; only the printing 2 will be revealed.

Similarly, if one illuminates this face only with a light of wavelength λ ₂ , only the printing 3 will be revealed. On the other hand, and as shown schematically in FIG. 4, if the face 10 of the bill is alternately illuminated with light sources of wavelength λ! and λ ₂ , alternating them with respect to each other, with a frequency sufficient to cause a stroboscopic effect, then the retinal persistence that a person observing the overlap area 4 of the two printed layers will show. hidden information IC which will be perceived and interpreted without ambiguity with respect to the person seeking to authenticate the document, in this case the ticket 1.

The embodiment illustrated in FIGS. 5 to 8 is very close to the previous one. In this case, on the front face 10 of the ticket 1, there is a first impression 2 in all respects identical to that which has been shown in Figure 1.

On the other hand, the second printing is performed, not on the same front face 10 but on the reverse side 11, so that the areas A and A 'are in register.

This is shown in FIG. 7 in which the overlap zone of the two impressions 2 and 3 is always referenced 4.

Of course, this presupposes that the support itself is not absolutely opaque and in particular the luminescence color emitted on the back (observer considered on the front) during illumination by stroboscopic effect, but this is the case of the papers used. to print value documents.

It is also conceivable to proceed locally with partial or total deopacification (transparency) by a chemical or physical treatment or by an earlier operation capable of generating this property to further improve the appearance effect of the hidden information.

In the same way as before, but having light sources of wavelengths at! and λ ₂ arranged on either side of the ticket, and by performing illumination under stroboscopic effect, the hidden information IC will then be revealed by the superimposition of the two impressions 2 and 3, at the level of the zone 4. This information is then visible by transvision, for the observer placed on one side or the other.

FIGS. 9 and 10 show three different embodiments of impressions 2 and 3, each being in the form of a pattern of parallel lines, but with lines of the printing 2, oriented at 90 ° with respect to those of printing 3.

When we consider one or the other of these impressions, no particular image is associated with these impressions. However, when one considers their superposition thanks to the retinal persistence obtained under stoboscopic effect, then hidden images IC that the observer identifies immediately are revealed (figure 11).

In this case, from left to right, this hidden information IC is constituted respectively by the acronym of the pound sterling, the sign of the dollar, and the number 5.

In the embodiment of Figures 12 to 15, we are not dealing with two impressions but three.

These impressions are referenced 2, 2 'and 2.

Again, when considering each of these impressions, no particular image is associated with these impressions. However, when we consider their superposition of Figure 15 revealed by stroboscopic lighting, we quickly identify the hidden information consisting of the number 5.

These three prints can all be made on the same face of the security element. However, one or two of them may be affixed to a second face of the security element. Preferably, each impression is made using a material whose revelation wavelength is different from the other two. However, it is conceivable that an impression for two of these layers is revealed with light of the same wavelength. This is also the case for two layers only if these two layers are on opposite sides.

FIGS. 16 to 19 show again an embodiment similar to that of FIGS. 1 and 2, namely that the two prints 2 and 3 are made on the same front face of the ticket 1.

However, in this context, the overall outline of each of the prints 2 and 3 is strictly identical and each print has a perfect overlap area A and A 'constituting the area 4.

In the same way as for the embodiment of FIGS. 1 and 2, alternately illuminating the front face of the note using wavelength lights λ! and λ ₂ , under stroboscopic effect, the hidden information which occupies zone A and A 'is then revealed.

As to the embodiment of FIGS. 20 and 21, it is common to the embodiment just described that the impressions 2 and 3 are exactly superimposed, but this in the form of an impression 2 made on the front face 10, and an impression 3 made on the reverse side 11.

Under the wavelength λ _1; and considering the impression 2, the density of lines or points of this print is defined in such a way that the density of A, namely dA, is equal to the density of B, namely dB. Likewise, as regards the printing 3 illuminated by a source of wavelength λ _2, the density of lines or points of this layer 3 is defined in such a way that this density relative to the area A '(ie dA ') is equal to the density of the area C (ie dC).

By illuminating the set sequentially using wavelength illumination sources A! and λ ₂ then, three options are possible for overlays:

Thus, when dA + dA 'is greater than dB, and dA + dA' greater than dC, zones B and C being without overlap, then the hidden information is reconstituted by part. In the second case where dA or dA 'is less than or equal to dA + dA', which is less than dB + dC, the zones B and C overlapping at least partially, then the information appears in negative. Finally, in the third case, that is, when dA + dA 'is greater than dB + dC, themselves greater than or equal to dB or dC, the zones B and C overlapping at least partially, so that information appears positive.

In Figure 24 is shown a printing 2 applied to the front face 10 which is formed of a set of distinct points. The printing 2 is seen in section in FIG. 25. In FIG. 26, the hidden information IC is embodied by a dashed outline for clarity in the figure but is indistinguishable in reality.

FIGS. 27 and 28 show a second printing 3 also made up of dots distinct from each other printed in such a way that there is an overlap of some of these dots with those of the printing 2. The printing 3 can be realized either on the front side 10 or on the back side 11. In FIG. 29, the hidden information IC is embodied by a dashed outline for clarity in the figure but is indistinguishable in reality.

In doing so, considering FIGS. 30 to 32, whether the prints are made on the same face 10 (FIG. 31) or on the opposite faces 10 and 11 (FIG. 32), then the hidden information IC consisting of the number 50 is revealed. since in this overlap region 4 the dot density is substantially less than half in this case the remainder of the area of the impressions 2 and 3 overlapping the security element.

In Figures 33 and 34 are shown other forms of printing 2 and 3 which are observed to simulate a stereoscopic binocular vision of a subject S in a scene D, as would an observer in real life.

In this case, the subject S is in the center and represents a seated person, drawn with an outline. The decor D or background, also drawn line, is made up of steps at the bottom and parts of walls at the top. The two images related to the decor are viewed from slightly different angles.

In this case, the hidden information IC is the relief of the central subject generated by the interpretation of the brain of an observer of the images observed thanks to the stroboscopic effect when the frequency of alternation of the illuminations makes it possible to erase any relative movement of the images. images between them and thus generate the stereoscopic effect. So in this case, if dA is the density of the central subject of the print 2 under the wavelength λ! and dA 'that of the subject of the printing 3 under the wavelength λ ₂ , then in superposition the sum dA plus dA' is equal to dA or dA '(the subjects are merged). On the other hand, the sum of the density dB of the decoration of the printing 2 under the wavelength λ! with the density dC of the same decoration of the printing 3 under the wavelength at ₂ .is greater than dB and dC considered in isolation.

In Figures 35 and 36 is shown by way of example a device 5 which reveals the hidden information IC within a security element as described above.

In this case, this device here has the form of a housing 5 with a lower portion 50 and an upper portion 51, which has a 52 observation window through. The lower part and the upper part are separated by an opening or slot 53 formed at least partially in the casing 5 and in which a flat document-value can be placed on which the security element to be revealed can be placed to submit it to authentication according to the invention.

Of course, the housing 5 contains light sources of wavelength λ! and λ ₂ or more if needed. These light sources are referenced 6 and 7.

These light sources, of the diode type, are arranged and connected to an electronic card, itself provided with an on / off button 80, with a battery, for example of the Li-ion type, provided with a USB port 82. Of course, other power modes may be considered as the mains or a standard non-rechargeable battery, etc.

Not shown in this document, another variant is the case where the light sources are located on the same side when the prints 2 and 3 are on the same side. The shape itself of the housing 5 can then change. It is not absolutely essential to have a slot 53 to insert the sample to be authenticated. Indeed, the latter is only there to provide a penumbra conducive to discerning colors of luminescent materials. Indeed, if one carries out the authentication in a place already plunged in the penumbra or then with a removable cache in the targeted place, this will obtain the same result.

Claims (10)

A security element which comprises a support (1) on which is present at least one impression (2; 2 ';2; 3), which comprises a first impression (2) invisible to visible light, but revealed under a first range of wavelengths (λι) outside the spectrum of visible light, and a second impression (3) invisible to visible light, but revealed in a second wavelength range (λ ₂ ) outside the spectrum of visible light; that said first and second impressions (2, 3) extending in partially overlapping regions, thus constituting at least one overlap zone (4), characterized in that it comprises hidden information which is constituted by said at least one overlapping area (4), hidden information (IC) which is revealed under alternating light illumination illuminating under two wavelength ranges corresponding respectively to said first and second ranges of wavelengths (λ, and λ ₂ ). 2. Security element according to claim 1, characterized in that said second wavelength range (λ ₂ ) is different and outside said first wavelength range (Afi. 3. Security element according to claim 1 or 2, characterized in that it comprises at least one other impression (2 ', 2) invisible to visible light, but revealed in a range of wavelengths outside the visible wave spectrum, this range of wavelength being different and outside the other ranges of wavelength (λ ₄ and λ ₂ ), that this at least one other impression (2 ', 2) presents, jointly with the other prints (2, 3), at least one overlapping area (4), and said at least one overlapping area (4) constitutes at least one hidden information (IC) which is revealed under strobe light alternating lightings in wavelength ranges corresponding respectively to said first, second and other ranges of wavelengths. 4. Security element according to one of claims 1 to 3, characterized in that said hidden information (IC) is an image, a number or a number, a text, a code, an impression of relief generated by the brain an observer or a combination of these. 5. Security element according to one of the preceding claims, characterized in that all the impressions (2, 3; 2 ', 2) are present on the same face (10; 11) of said support (1). 6. Security element according to one of claims 1 to 4, characterized in that at least one of said impressions (2; 3; 2 '; 2) is present on a face (10) of said support (1), while at least one second print (2; 3; 2 '; 2 ") is present on the opposite face (11). 7. Security element according to one of the preceding claims, characterized in that said first and / or second printing (s) (2; 3; 2 '; 2) is / are continuous (s), it is ie constitutes (s) a flat. 8. Security element according to one of the preceding claims, characterized in that said first and / or the second printing (s) (2; 3; 2 '; 2) is / are discontinuous (s), it is that is, are (are) at least two distinct and separate regions that together constitute a frame. 9. Security element according to claim 8 wherein the two prints (2, 3) are discontinuous and consist of several distinct and separate regions, characterized in that under stroboscopic illumination the density of coverage of the medium (1) by said impressions (2, 3) in said at least one overlap area (4) is substantially smaller, ideally half the coverage density of the support by said impressions, outside the overlap area (4). 10. Security element according to claim 8 wherein the two prints (2, 3) are discontinuous and consist of several distinct and separate regions, characterized in that under stroboscopic illumination the coverage density of the medium (1) by said impressions (2, 3) in said at least one overlap region (4) is substantially greater, ideally twice the coverage density of the support by said impressions, outside the overlap area (4).