CN108883651B

CN108883651B - Security element comprising hidden information and valuable document comprising a security element

Info

Publication number: CN108883651B
Application number: CN201680081829.6A
Authority: CN
Inventors: 吉尤姆·沙波; 格扎维埃·博尔德
Original assignee: Oberthur Trust
Current assignee: Foucault second Ltd.; ArjoWiggins Security SAS
Priority date: 2015-12-18
Filing date: 2016-12-19
Publication date: 2020-08-07
Anticipated expiration: 2036-12-19
Also published as: KR102637134B1; EP3390064A1; ZA201803981B; RU2700008C1; FR3045907A1; EP3390064B1; WO2017103252A1; CA3008740A1; CN108883651A; AU2016369458B2; KR20180113994A; PL3390064T3; FR3045907B1; ES2753152T3; AU2016369458A1

Abstract

The invention relates in particular to a security element comprising a support (1) on which at least one printing (2; 2'; 3) is present, the at least one printing comprising a first printing (2) and a second printing (3), the first printing being invisible to visible light but being outside a first wavelength range (lambda) of the visible spectrum₁) Lower exposure, the second printing member being invisible to visible light but outside the visible light spectrum in a second wavelength range (λ)₂) Revealing that said first and second printing members (2, 3) extend in areas partially overlapping each other, so as to form at least one covering area (4), characterized in that the security element comprises a hidden Information (IC) formed by said at least one covering area (4), in a respective correspondence with said first and second wavelength ranges (λ [)₁And λ₂) And the light is exposed under stroboscopic illumination of alternate illumination in two wavelength ranges.

Description

Security element comprising hidden information and valuable document comprising a security element

Technical Field

The present invention relates to security elements. The invention also relates to a value document comprising at least one such element.

Background

The invention applies more particularly to security elements for valuable documents, such as for example trust documents or similar.

The expression "trusted document" refers to all documents such as banknotes, checks, bank cards or other media for transferring an amount of money.

The expression "documents like" refers to all documents such as identification cards, passports or driver licenses issued by the national authorities for proving the identity of a person or the right to drive a vehicle.

Such expression also refers to any type of document for authenticating an object of value, such as for example a label to be placed on a garment. It also refers to any document used to validate tax payments, such as tax stamps.

In this field, and in particular for banknotes, it is known to attach one or more security elements of various types to protect these documents against possible fraudulent manufacture.

In this way, there are different types of security elements that respond to the classification by level, and the present invention relates to a so-called secondary security element, i.e. a widely used tool whose authentication requires a tool, such as an ultraviolet lamp, particularly whose use is widely understood by the public.

The skilled person is familiar with document EP 1567358, which describes a security device comprising at least two regions comprising material, wherein the two or more regions have substantially the same visible colour under first viewing conditions (including visible light) and a different visible colour under second viewing conditions (a combination of visible light and any UV light having a wavelength substantially in the range of 235nm to 380 nm).

If the security element is easy to implement, it is still threatened by the general public to increasingly obtain legal ink printing solutions in the above-mentioned range (i.e. 235nm to 380nm) by means of inkjet or fluorescent "toners" (powder inks), or even illegal solutions using materials for example marketed by websites hosted on "darknets".

To enhance the security measures based on fluorescent materials, document EP 1719637 discloses the use of a transparent window extending through the relevant document, a transparent layer for blocking UV radiation in the area defined by the transparent window, and a first pattern of fluorescent ink printed between the UV-blocking layer and the transparent window.

In this way the pattern is normally not visible, but becomes visible from both sides if illuminated by UV from one side of the window. The pattern is still invisible when illuminated from the side of the UV-blocking layer.

Of course, with a combination of fluorescent inks of different colors ideally placed on either side of the UV blocking layer, a complex effect can be obtained that further complicates counterfeiting.

However, this solution has the disadvantage that the transparent window has to be integrated into the paper document or that a polymeric substrate has to be used and materials added to form the UV-blocking layer. This has a large impact on the complexity of the substrate fabrication and its cost.

Document WO 2014177375 discloses a security element consisting of at least three layers, each layer comprising a different material, wherein a first material, a second material and a third material are capable of interacting with a first electromagnetic emission, a second electromagnetic emission and a third electromagnetic emission, constituting an animated pattern as a whole, thanks to the ability to emit precisely and separately in each individual emission, in order to excite in particular a sequential illumination of one of the materials.

This shows the principle of cinematography with patterns that appear to become active when a series of lights are on. For economic reasons, the limitations of such systems are soon seen, where the number of images of dynamic patterns allowing mobility will be kept low to reduce the amount of swelling of the ink to be printed, and at the same time the number of different lights in the device for verifying security.

Inks reactive to Ultraviolet (UV) light are also more commonly known, which emit a luminescent signal in the visible range (400nm-780nm) under the action of a lamp having a wavelength of less than 400 nm. These inks constitute a common example of secondary security.

Some pigments or ink dyes are also known to absorb at precise wavelengths. They require lamps that emit at selected wavelengths.

With the selected wavelengths, wavelengths of 365nm, 312nm, and 254nm are known to be found.

However, the main drawback of the pigments or luminescent dyes of these inks is the absorption of the ultraviolet emission over a broad spectrum with more or less intensity.

In addition, an ultraviolet lamp composed of a fluorescent tube emits a broadband spectrum. This makes it easier for counterfeiters to work with standard ultraviolet lamps to see the area designed for secondary fluorescent color certification. Thus, as mentioned above, they can forge documents with the aid of commercial types of ink.

However, there are some luminescent materials whose absorption peaks are targeted across a narrow band, and uv emitters consisting of L ED (light emitting device) which emit only over a narrow spectral band around a precise wavelength, and which also offer more technical possibilities in terms of energy consumption, on/off cycles, etc. than vacuum tubes commonly known as neon lamps.

However, such a device is still inexpensive, especially since the L ED case improves, and it also combines the advantages of small footprint, allowing for the manufacture of miniaturized devices.

On the other hand, devices are known having a luminescent material called "anti-stokes" which emits light in the visible under the action of a laser calibrated to a defined wavelength.

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

Such a security element is inherently difficult to manufacture and requires special equipment to identify it.

Document WO 2015/144646 constitutes further prior art, which discloses some features of the preamble of claim 1 of the present application. This document proposes to reveal a first image recognizable by itself under a certain illumination (short ultraviolet), then to filter the short UV through a layer when moving from one illumination to another to obtain a direct switch between the two images and to reveal a second image recognizable by itself under the other certain illumination (long ultraviolet).

Thus, there has proven to be a need to provide element security that is invisible to the naked eye and visible light, not in the material itself (pigments, inks or substrates that affect manufacturing costs), but in the placement of the printed pattern and the use of an economical authentication device, so as to effectively resist any attempt to reproduce.

Disclosure of Invention

From this point of view, the invention proposes a security element comprising a support on which there is at least one printing. Such an element comprises a first printing member which is invisible to visible light but is revealed at a first wavelength range outside the visible light spectrum, and a second printing member which is invisible to visible light but is revealed at a second wavelength range outside the visible light spectrum. The first and second printing members extend into a partially overlapping region to form at least one overlapping region. Such an element comprises hidden information constituted by said at least one overlapping area, which hidden information is revealed under stroboscopic illumination alternately illuminated in two wavelength ranges corresponding to said first and second wavelength ranges, respectively.

According to other non-limiting and advantageous features of the invention:

-the second wavelength range is different from and outside the first wavelength range;

the element comprises at least one further print, which is invisible to visible light but is exposed in a wavelength range outside the visible light spectrum, which is different from and outside the other wavelength ranges, so that the at least one further print and the other prints jointly present at least one mutually overlapping region, and the at least one mutually overlapping region constitutes at least one item of hidden information, which is exposed under stroboscopic illumination alternately illuminated in the wavelength ranges corresponding to the first, second and other wavelength ranges, respectively;

-the hidden information is an image, a graphic or a number, text, a code, a relief print produced by the brain of the viewer or a combination thereof;

-all printing members are present on the same face of the support;

-at least one of said printing members is present on one face of said support, while at least one second printing member is present on the opposite face;

-said first and/or second printing member is continuous, i.e. constitutes a "platform";

-said first and/or second printing member is discontinuous, i.e. is constituted by at least two distinct and separate areas which together constitute a grid;

the two printing members are discontinuous and are made up of several distinct and separate areas, and under stroboscopic illumination, the density of coverage of the support covered by the printing members in the at least one overlapping area is substantially less, ideally half that of the support covered by the printing members outside the overlapping area; and

the two printing members are discontinuous and are constituted by several distinct and separate areas, and under stroboscopic illumination, the density of coverage of the support covered by the printing members in the at least one overlapping area is significantly greater, ideally twice the density of coverage of the support covered by the printing members outside the overlapping area.

Drawings

Other features and advantages of the present invention will appear from the following description of preferred embodiments of the invention. The description is given with reference to the accompanying drawings, in which:

fig. 1 and 2 are plan views of a banknote incorporating a security element according to the invention, fig. 1 revealing only a first printing member, while fig. 2 shows only a second printing member;

figure 3 is a longitudinal section through the banknote of figures 1 and 2 showing a partial covering of the printing member;

fig. 4 is a diagram illustrating the principle implemented for revealing hidden information within the print to the viewer.

Figures 5 and 6 are respectively a top view and a bottom view of a banknote incorporating a security element according to the invention, each printed item being present on a large face of the banknote;

FIG. 7 is a view similar to FIG. 3 of this second embodiment;

FIG. 8 is a view similar to FIG. 4;

FIG. 9 is a plan view of three alternative embodiments of the first printing member;

FIG. 10 is a plan view of three variations of a second printing member combined with the first printing member of FIG. 9 when strobed illumination is activated;

FIG. 11 is a plan view of the printings of FIGS. 9 and 10 superimposed and their revealed hidden information;

fig. 12-14 are plan views of three printing members, and fig. 15 shows a superposition of the three printing members with their exposed hidden information;

fig. 16 to 19 are views similar to fig. 1 to 4, respectively, showing another modification of the embodiment;

fig. 20 to 23 are views similar to fig. 5 to 8, respectively, showing another modification of the embodiment;

figures 24 to 26 show a first print, in plan view, a cross-section of the print and its substrate, respectively, and a second plan view with hidden information indicia hidden by dashed outline for greater clarity but in reality illegible;

fig. 27 to 29 are views similar to fig. 24 to 26 with respect to a second printing member cooperating with the first printing member in the above figures;

FIG. 30 is a plan view as seen by an observer when the two prints of FIGS. 24 and 27 are subjected to stroboscopic illumination;

figures 31 and 32 are cross-sectional views of the substrate receiving the two printing members, depending on whether the printing members are present on the same side of the support;

figures 33 and 34 are front views of two printing members seen together to create a three-dimensional effect;

finally, figures 35 and 36 are respectively a simplified perspective view and a cross-sectional view of a device that can be used to make visible the hidden information forming an integral part of the security element.

Detailed Description

All the following description will refer to a security element comprising at least two prints. In all these embodiments, the prints are made with the aid of ink, for example in the form of lines, with guilloches, as a background for coins, etc.

These prints are made by performing various printing techniques such as offset printing, screen printing, gravure printing, flexography printing, inkjet or laser, etc., to name a few.

More specifically, with the present invention, emphasis will be placed on security elements by offset printing. However, this is a simple illustration and the use of offset printing requires the availability of a register printing unit, as will become clear later in the description.

In this way, it should be understood in the present application that at least two prints or two patterns are theoretical terms, valid in the figures, planes and "layouts", when they are identified (or registered) (i.e. they define relative positions between them), when they are edge-to-edge (or continuous), when they are globally perpendicular to each other, etc., but in reality undergo minimal placement deviations after having fabricated them on the proposed valuable document and furthermore on several valuable documents compared to each other. For example, it is generally noted that the offset is preferably +/-0.01mm for the placement tolerance between two groups of simultaneous or consecutive prints, whereas a tolerance of at least +/-0.2mm in the worst case must be envisaged when the prints are made in two separate passes thus misaligned.

As will also be described in detail below, the print is made with devices such as visible light and inks that are invisible to the naked eye but show up in wavelength ranges outside the visible spectrum.

Advantageously, these prints are made, for example, with inks that react to wavelengths in the ultraviolet range, or by using inks that react to wavelengths in the infrared range.

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

When an ink is used that reacts to wavelengths in the ultraviolet range, the wavelength range used will be less than 400nm and in particular have absorption peaks centered at 365nm, 312nm and 254 nm.

When inks are used which react to wavelengths in the infrared range, this relates to a wavelength range of more than 780nm and in particular has an absorption peak centred around 980 nm.

In this way, with reference to figures 1 to 3, these relate to a banknote 1 whose large opposite faces 10 and 11 are coated with various printing members and security devices known to those skilled in the art and which will not be mentioned further below.

On the front side 10 of the banknote, a printing element is provided with the reference number 2, which represents two regions with the reference numbers a and B.

In this exemplary embodiment, the printing member 2 has the form of a square continuing at a point on one side thereof. The area a has a contour in the form of a diamond, while the area B corresponds to the rest.

Referring now to fig. 2, on the same front face 10 of the banknote, this shows only the second printed member 3 comprising two areas a' and C. The areas a' are in register with the areas a of the first print 2 so that they are completely superimposed and take on the same form and the same dimensions as the areas a. However, region C is located on the right side of region a' and is opposite to region B. In a variant not described, the region C may have a different and asymmetrical form to the region B.

In this way, with reference to the section of fig. 3, it is evident that the

prints

2 and 3 partially overlap to constitute an overlap region 4 constituted by the overlapping regions a and a'.

As mentioned above, the first printing member 2 is visible light-invisible but visible light-invisibleA first wavelength range lambda outside the spectrum₁The lower exposed material. As regards the second printing member 3, it is made by means of a second ink invisible to visible light and visible in a second wavelength range outside the visible spectrum, λ₂Different from and outside the first wavelength range.

Considering these characteristics, it can be understood that if the wavelength λ is used₁Will illuminate the banknote above its front face 10, only the printing member 2 will be revealed.

Similarly, if only the wavelength λ is used₂Will illuminate this side and will only reveal the printing member 3. However, as schematically shown in FIG. 4, if a wavelength λ is used instead₁And λ₂By alternating them with respect to each other, causing a stroboscopic effect with sufficient frequency, the persistence of the retina of the person observing the overlapping area 4 of the two printed layers will see (will reveal, i.e. make visible) the hidden information IC, which will be clearly perceived and interpreted with respect to the person who wants to authenticate the document (in this case the banknote 1).

Throughout the present application, the expression "hidden information" refers to information that is not discernible from the outset, but is recognized by an observer under certain observation conditions, for example because it is intrinsically meaningful to the observer.

The embodiment shown in fig. 5 to 8 is very close to the previous embodiment. In this case, on the front side 10 of the banknote 1, this relates to a first printing member 2 which is identical in all respects to that shown in fig. 1.

However, the second print is not made on the same front face 10, but on the reverse face 11, so that the areas a and a' are in register.

As shown in fig. 7, the overlapping area of the two

prints

2 and 3 is still marked with 4.

This presupposes, of course, that the substrate itself is not absolutely opaque and, in particular, the emission color emitted onto the reverse side (the viewer considered on the front side) during irradiation by the stroboscopic effect, but this is the case for paper sheets for printing value documents.

Partial or total de-opacifying (transparency) may also be performed locally via chemical or physical treatment or by previous operations capable of producing this property to further improve the visualisation of the hidden information.

In the same way as before, but with the wavelength λ arranged on either side of the banknote₁And λ₂And by creating illumination under stroboscopic effect, the hidden information IC will emerge at the level of the area 4 by the superposition of the

prints

2 and 3. This information is visible through perspective to a viewer on one side or the other.

Fig. 9 and 10 show three different embodiments of

printing members

2 and 3, each in the form of a grid of parallel lines, but with the lines of printing member 2 oriented at 90 ° with respect to the lines of printing member 3.

When considering one or the other of these prints, no specific image is associated with these prints. But considering that they are all suddenly revealed by the superimposition of the persistence of the retina obtained under the stroboscopic effect (figure 11).

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

In the embodiment of fig. 12 to 15, this relates not to two printing members, but to three printing members.

The reference numbers of these prints are 2, 2' and 2 ".

Here again, considering each of these prints, no specific image is associated with these prints. But considering the superposition of fig. 15, which they reveal by stroboscopic illumination, the hidden information constituted by the number 5 is rapidly identified.

The three prints may all be made on the same side of the security element. One or both of them may be attached to the second face of the security element. Each print is preferably made of a material whose exposure wavelength is different from the other two. However, printing of two of these layers may be revealed with the same wavelength of light. This is also true for two layers only when the two layers are on opposite sides.

Fig. 16 to 19 show a further embodiment similar to that of fig. 1 and 2, in particular two printed

members

2 and 3 made on the same front face of the banknote 1.

In this case, however, the overall profile of each

print

2 and 3 is exactly the same, and each print comprises perfect coverage areas a and a' constituting area 4.

In the same way as in the embodiment of fig. 1 and 2, at a wavelength λ₁And λ₂Alternately illuminating the front side of the banknote, the hidden information occupying regions a and a' is revealed under the stroboscopic effect.

For the embodiment of fig. 20 and 21, the common factor with the embodiment just described is the fact that the

prints

2 and 3 are exactly superimposed, but in the form of a print 2 made on the obverse 10 and a print 3 made on the reverse 11.

At a wavelength λ₁And considering print 2, the density of the lines or dots of this print is defined so that the density of a (in particular dA) is equal to the density of B (in particular dB). Similarly for wavelength λ₂The light source of (a) defines the density of lines or dots of the layer 3, so that this density (or dA ') with respect to the area a' is equal to the density (or dC) of the area C.

By means of a wavelength lambda₁And λ₂The light sources of (a) sequentially illuminate the whole, there can be three options for superposition:

in this way, when dA + dA 'is greater than dB and dA + dA' is greater than dC, regions B and C do not overlap and the hidden information is partially reconstructed. In the second case, where dA or dA 'is less than or equal to dA + dA' (which is less than dB + dC), regions B and C at least partially overlap, the information appears negative. Finally, in the third case, i.e. when dA + dA' is greater than dB + dC (themselves greater than or equal to dB or dC), the regions B and C are at least partially covered and the information appears positive.

Fig. 24 shows a printing member 2 applied to the front side 10 formed by a set of different dots. In fig. 25, the printing material 2 is viewed in cross section. In fig. 26, the hidden information IC is represented by a dashed outline for better clarity in the drawing, but is not actually distinguishable.

Fig. 27 and 28 show a second printing member 3, which is also composed of dot prints that differ from each other, so that some of these dots overlap with the dots of printing member 2. The printing member 3 can be made on the obverse side 10 or on the reverse side 11. In fig. 29, the hidden information IC is represented by a dashed outline for better clarity in the drawing, but is not actually distinguishable.

In this way, considering fig. 30 to 32, the printed matter is made on the same face 10 (fig. 31) or on the opposite faces 10 and 11 (fig. 32), the hidden information IC constituted by the number 50 being revealed, since in this overlapping area 4, in this case, the density of dots is substantially less than half of the rest of the face of the printed

matter

2 and 3 overlapping the security element.

Fig. 33 and 34 show other forms of

prints

2 and 3 which are observed to simulate stereoscopic binocular vision of the object S in the scene D, as the observer does in real life.

In this case, the object S is located in the middle and represents a seated person outlined. The scene D or background (also drawn with lines) itself is made up of the steps at the bottom and the wall parts at the top. The two images associated with the scene are considered to be at slightly different angles.

In this case, the hidden information IC is a relief of the central object produced by the interpretation of the image observed via the stroboscopic effect by the observer's brain, when the alternating illumination frequency sticks together any relative movement of the images and thus produces a stereoscopic effect. Thus, in this case, if dA is at the wavelength λ₁The density of the central objects of the lower printing member 2, and dA' is at the wavelength λ₂Density of objects of lower print 3, then the sum of dA plus dA 'equals dA or dA' (objects are combined) when superimposed. In addition, at the wavelength λ₁Density dB of the scene of the lower print 2 and at the wavelength λ₂The sum of the densities dC of the same scene of the lower print 3 is greater than dB and dC considered separately.

By way of example, fig. 35 and 36 show a device 5 which reveals a hidden information IC within a secure element as described above.

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

Of course, the housing 5 contains the wavelength λ if desired₁And λ₂Or more light sources. The reference numerals of these light sources are 6 and 7.

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

Another variant, which is not disclosed in this document, is the case when the light sources are located on the same side when the

prints

2 and 3 are thus located on the same side. The form of the housing 5 itself may vary. It is not absolutely essential to have a slot 53 for inserting the sample to be verified. In fact, the latter only provides half-light that contributes to a proper color discrimination of the luminescent material. In fact, this would yield the same result if authentication is performed when already stuck in a semi-optical position or where the cover is movable to a target position.

Claims

1. A security element comprising a support (1) on which at least one print (2; 2'; 3) is present, said at least one print comprising a first print (2) that is invisible to visible light but in a first wavelength range (lambda) outside the visible spectrum, and a second print (3)₁) Exposed, the second printing member is invisible to visible light but in a second wavelength range (lambda) outside the visible spectrum₂) The first printing member (2) and the second printing member (3) are exposed and extend to the partially overlapped area,forming at least one overlap region (4),

characterized in that the security element comprises a hidden Information (IC) constituted by the at least one overlapping area (4),

"hidden information" refers to information that is not discernible from the beginning but is recognizable by an observer under certain observation conditions,

the hidden Information (IC) is only in the first wavelength range (λ)₁) And a second wavelength range (lambda)₂) Is exposed under stroboscopic illumination of alternating illumination in the two wavelength ranges,

the hidden Information (IC) is an image, a graphic or number, text, a code, a raised print produced by the brain of the viewer, or a combination thereof.

2. Security element according to claim 1, characterised in that said second wavelength range (λ)₂) Different from the first wavelength range (lambda)₁) And outside the first wavelength range.

3. Security element according to claim 1, characterised in that it comprises at least one further print (2', 2") which is invisible to visible light but emerges outside the visible spectrum at a third wavelength range which is different from the first wavelength range (λ ™)₁) And a second wavelength range (lambda)₂) And outside the first and second wavelength ranges, so that the at least one further print (2', 2') together with the first and second prints (2, 3) presents at least one overlap region (4), and the at least one overlap region (4) constitutes at least one item of hidden Information (IC) which is revealed under stroboscopic illumination of alternating illumination in wavelength ranges corresponding to the first, second and third wavelength ranges, respectively.

4. Security element according to one of claims 1 to 3, characterised in that all prints are present on the same face (10; 11) of the support (1).

5. A security element according to any one of claims 1 to 3, characterized in that at least one of the prints is present on a face (10) of the support (1) and a second print (3) is present on a face (11) opposite to said face (10).

6. A security element according to any one of claims 1 to 3, wherein the first and/or second printing member is continuous, i.e. constitutes a "platform".

7. The security element according to any one of claims 1 to 3, characterized in that the first and/or the second printing is discontinuous, i.e. is composed of at least two distinct and separate areas which together constitute a grid.

8. The security element according to claim 7, wherein the first and second prints are discontinuous and are made up of several distinct and separate areas, characterized in that, under stroboscopic illumination, the density of coverage of the support (1) covered by the first and second prints in the at least one overlapping area (4) is substantially less, half the density of coverage of the support covered by the prints outside the at least one overlapping area (4).

9. The security element according to claim 7, wherein the first and second prints are discontinuous and are made up of several distinct and separate areas, characterized in that, under stroboscopic illumination, the density of coverage of the support (1) covered by the first and second prints in the at least one overlapping area (4) is significantly greater, twice the density of coverage of the support covered by the prints outside the at least one overlapping area (4).