EP2655740A1

EP2655740A1 - Element for security document comprising an optical structure

Info

Publication number: EP2655740A1
Application number: EP11810660.8A
Authority: EP
Inventors: Michel Camus
Original assignee: ArjoWiggins Security SAS
Current assignee: ArjoWiggins Security SAS
Priority date: 2010-12-22
Filing date: 2011-12-15
Publication date: 2013-10-30
Also published as: FR2969670A1; US20140151996A1; FR2969670B1; WO2012085773A1

Abstract

The invention relates to a security element comprising a substrate provided with a first face equipped with an optical structure and with a second face, characterized in that it comprises at least a first pattern and a second pattern inscribed on the second face of the substrate, the first pattern being observable through the optical structure along a first angle of observation at a first position on the second face, the second pattern being observable through the optical structure along a second angle of observation, different from the first angle, at a second position on the second face that is different from the first position, the first pattern and the second pattern being at least partially identical.

Description

ELEMENT FOR SAFETY DOCUMENT HAVING AN OPTICAL STRUCTURE

The present invention relates to a security element comprising a substrate provided with a first face equipped with an optical structure which makes it possible to vary the appearance of the security element when the observation angle is modified.

Such security features are primarily intended to be inserted in or on security documents.

Security document means a valuable document, for example, a means of payment, such as a bank note, a check or a restaurant ticket, a lottery ticket, a ticket or a ticket giving access to a cultural or sporting event and / or a document for the identification of persons, such as an identity card, a visa, a passport or a driving license.

The financial value they represent or the value to which they give access make these documents particularly sensitive in terms of security. Similarly, the authentication of the person and access to certain rights given by these security documents easily show that it is essential to guard against attempts to falsify or counterfeit in the field of security documents. There is therefore a definite need for elements making it possible, in a simple and accessible manner for everyone, to authenticate and / or identify the security document carrying the element.

It is known to provide security elements with optical structures such as lenticular arrays that are associated with specific impressions to produce movement, depth, and relief effects so as to guard against tampering or tampering. forgery of a security document. One of the main advantages of these optical structure security elements is that they can not be duplicated by photocopy or by simple printing.

Generally, such security elements equipped with optical structures are integrated in a security document so that a part is exposed to the air and therefore visible to the observer. The difference in refractive index between the material of the optical structure and the air produces a refraction of the light rays which is at the origin of the effects of movement during the observation, in particular by magnifying Moiré effects.

The known principle of magnifying Moiré creates a depth effect or an impression of motion when a change of viewing angle is due to the relative position between two different images or patterns printed on the security element relative to to the lenticular network. For example, a magnifying Moiré effect is obtained by means of an array of images or patterns in which the images or patterns have the same distribution as the lenses of the lenticular array but with an angular offset. By "same distribution" is meant that the spacing pitch between the images is constant and identical to that between the lenses. A magnifying Moiré effect can also be obtained when the spacing pitch between the images varies regularly and slightly with respect to that between the lenses which is constant.

Security elements with optical structures creating a depth effect or a movement impression are visually appealing and relatively difficult to copy identically. In addition, these effects are generally associated with variations in the size of the pattern and the magnitudes of motion that are a function of the magnification rate. However, the complexity of the optical effects generated makes them sometimes difficult to authenticate and especially to distinguish, especially in case of forgery. For example, a counterfeit security element with a similar but slightly different complex optical effect will be difficult to recognize with respect to an original security element since the effect itself is complex.

The object of the invention is therefore to propose an alternative by proposing a new security element comprising an optical structure that presents new optical effects for authentication and / or simple and immediate identification.

For this purpose, the subject of the invention is a security element comprising a substrate provided with a first face equipped with an optical structure and a second face, characterized in that it comprises at least a first and a second pattern inscribed on the second face of the substrate, the first pattern being observable through the optical structure at a first angle of observation at a first position on the second face, the second pattern being observable through the optical structure at a second angle of observation, different from the first angle, at a second position on the second face different from the first position, the first and the second pattern being at less partially identical.

Advantageously according to the invention, the observer, varying the angle of inclination of the security element according to the invention, finds that the same pattern appears and disappears from a first position to appear and disappear, so that alternated, to a second position on the security element. This appearance of a single pattern at different positions on the security element is an easily recognizable optical effect and therefore allows a simple, immediate and unequivocal authentication and / or identification of the security element according to the invention.

A "same motif" means a single pattern or image that may have several occurrences whose appearance, ie, shape, appearance and / or or color, is substantially the same or different. less partially identical. For example the pattern is in the form of an alphanumeric symbol or is representative of a symbol, a logo, a character, a landscape, an object ...

For reasons of brevity and clarity, the at least partially identical first and / or second pattern may be referred to in the following as "the pattern".

Preferably the substrate is at least partially transparent or translucent. The substrate may for example be or comprise a film of a transparent or translucent thermoplastic material, for example polyester or PET. Similarly, the optical structure is at least partially transparent or translucent so that the pattern inscribed on the second face of the substrate is observable through the optical structure and the substrate.

According to a particular embodiment of the invention, a reflective or at least partially opaque or semi-reflective surface is observable at the first position under the second observation angle and at the second position under the first observation angle.

Advantageously, the appearance of the single pattern at a particular position on the security element and its disappearance, when it is replaced by a reflective or semi-reflecting surface at this particular position, enhances the contrast effect between the appearance and the disappearance which further facilitates the recognition and authentication of the security element.

According to a particular embodiment of the invention, the optical structure is composed of a lenticular network comprising a set of lenses. For example, the lenses of the lenticular array are cylindrical or hemispherical concave, convex or Fresnel and are arranged in a hexagonal, hexagonal compact or rectangular arrangement. Compact hexagonal means an arrangement according to which the lenses are included in a hexagonal shape with no space between them. Preferably, the lenticular network consists of coplanar hemispherical lenses arranged in staggered rows, hexagonal lenses arranged in "honeycomb" or juxtaposed cylindrical lenses.

The optical structure can be made by embossing, in particular by thermo-embossing or by embossing followed by ultraviolet crosslinking, or by molding. The optical structure may further comprise a printed lenticular network comprising lenses which may or may not be juxtaposed, for example by UV printing, for example by screen printing, gravure printing, letterpress printing or by inkjet printing.

Such arrangements of the lenses according to the invention provide optimum compaction to reveal a greater density of printing dots or pattern elements which are printed opposite the lenses. The overall resolution of the pattern is thereby increased. The security element is all the more easily authenticated.

According to yet another particular embodiment of the invention, the at least partially identical first and second patterns consist of a set of disjoint pattern elements, each pattern element being arranged facing a corresponding lens, and in that at said first position each pattern element is disposed of a first next to the center or the axis of said corresponding lens, and each pattern element at said second position is disposed at a second side, opposite to the first side, with respect to the center or the axis of said corresponding lens.

Thus, in the first position, each pattern element is arranged in the same way with respect to the corresponding lens. In particular, the pattern elements forming the first pattern are distributed in the same way as the corresponding lenses, that is to say with the same spacing pitch and without angular offset so as to avoid any Moiré effect.

Moreover, a single pattern element is arranged opposite a corresponding lens. Each lens is therefore associated with a single pattern element to make the pattern appear and disappear. In particular, according to the invention it is avoided to have several patterns or pattern elements facing a single lens. It is also avoided to have multiple partial images constituting an interlaced image facing a single lens to generate complex optical effects that are difficult to distinguish.

The pattern elements can be obtained by perforation, deposition and / or voids of material. For example, the pattern elements are obtained by metallization or demetallization of materials selected from: metals, metal compounds, alloys, varnishes or metallic inks, as described in EP279880. Alternatively, the pattern elements can be obtained by selective printing, in positive or negative, of an ink containing pigments chosen from: carbon black pigments, magnetic pigments, colored pigments, pigments visible under radiation UV or IR or a mixture of these. The pattern elements of the raster pattern can have varying shapes and / or sizes so as to form a multi-tone pattern.

The security element may comprise disjoint magnetic elements forming a magnetic code.

Advantageously, the pattern elements of the raster pattern can be obtained by selective printing of an ink containing magnetic particles or by application of a vacuum metallization. This motive wavelet thus constitutes a magnetic code having a particular magnetic response, linked to the pattern, which makes it possible to authenticate the security document carrying the security element.

For example, a banknote of a particular denomination comprising the security element with a particular halftone pattern that is related to the denomination, has a magnetic response associated with the denomination and which makes it possible to authenticate the banknote. The reading of the magnetic code also makes it possible to identify the cutoff automatically during a sorting machine treatment.

Magnetism is read or detected for example by means of inductive heads that measure magnetic flux variations. The magnetic particles can be applied in varying particle concentration layers to vary the flux to obtain a more accurate code or to increase the amount of codes that can be affected.

Advantageously, the magnetic code is optically masked since it merges with the raster pattern. The presence of the code can not therefore be detected visually but only by means of a suitable reading device.

Alternatively, the printing of the magnetic ink can be applied under the pattern elements so as to be masked by them.

According to a particular embodiment, the zone of the magnetic code comprises at least two magnetic materials having strong coercivities (for example greater than or equal to 1000 Oe (80 kA / m), more preferably at 2000 Oe (160 kA / m), or even at 4000 Oe (320 kA / m) and different but arranged on or in the security element so as to have substantially equal (and strong) remanence, as disclosed in US 2009/0008922 A1, for example by playing on the thickness and / or concentration The strong coercivity notably makes it possible to avoid fraudulent attempts to modify the magnetic code.

Alternatively, the security element may comprise a weakly coercive magnetic zone (for example between 10 and 500 Oe (800 A / m at 40 kA / m)) covered at least partially by a strongly coercive magnetic zone (preferably greater than 1000 Oe (80 kA / m)) which magnetizes the weakly coercive magnetic zone to avoid fraudulent attempts to modify the magnetic code, as disclosed in EP 1 618 006 B1. The weakly coercive magnetic zone comprises a plurality of independently magnetizable partial areas forming the disjoint bits or magnetic elements of the magnetic code.

According to another particular embodiment of the invention, the distance between the optical structure and the first or second pattern inscribed is preferably less than or equal to the focal length of the lenses of the lenticular array. Furthermore, according to the invention, the distance between the optical structure and the inscribed pattern is preferably greater than the radius of curvature in the center of the lenses of the lenticular array. The distance between the optical structure and the inscribed pattern is understood to mean the distance between the top of the lenses of the lenticular array and the second face of the substrate in a direction perpendicular to the surface of the support.

In the case of an example of a truncated hemispherical lens also called "plane-convex lens", that is to say resulting from the association of a plane diopter and a spherical diopter, the radius of curvature at center of a lens, the height and radius of the lens are bound by the following known formula: H (2Rc - H) = r ² .

The solution of this equation is: H = Rc - V (Rc ² - r ² ), in which "Rc" is the radius of curvature at the center of the lens, "H" is the height of the lens and "r" is the radius of the lens at the level of the plane diopter.

It will be understood that according to this formula resulting from classical geometry, there exists a determined relation between the height, the radius of curvature at the center of the lens and the diameter of the lens. The height of a lens can thus be determined from the radius of curvature and the diameter of the lens. One can therefore advantageously define a compromise between the thickness of the security element and the resolution of the pattern.

A satisfactory compromise between thickness and resolution is preferably obtained for a lenticular array whose lenses have a diameter of between 15 and 50 microns for a radius of curvature of between 10 and 40 microns. For example, for a lenticular array whose lenses have a diameter of 20 microns for a radius of curvature of 15 microns the patterns are preferably inscribed at a distance of between 20 and 30 microns.

For example, for a lenticular array whose lenses have a diameter of 50 microns for a radius of curvature of 30 microns the patterns are preferably inscribed at a distance of between 25 and 45 microns.

Preferably, each pattern element is inscribed on the face of the security element opposite a corresponding lens so as to have a width at most equivalent to the radius of the corresponding lens. This arrangement makes it possible to make the pattern appear and disappear in an adequate manner, that is to say that the time of appearance is substantially equivalent to the time of disappearance when the observer varies the angle of observation of the element. in a uniform manner over time. This allows an authentication and / or effective identification of the security element which allows the pattern to appear / disappear sufficiently to be easily observed by the observer.

With the arrangement defined above, the security element according to the invention has a reduced thickness while retaining a particularly effective appearance and disappearance effect for integration into security documents, even for documents relatively fine such as bank notes. Since banknotes generally have a thickness of about 100 microns, the security elements they carry must therefore not exceed this thickness approximately.

For example, a security element according to the invention may have a lenticular array comprising a set of identical truncated hemispherical lenses with a diameter of about 50 microns, for a radius of curvature of 30 microns and a height of about 14 microns. In this case, as explained above, the distance between the top of the lenses of the lenticular array and the inscribed pattern may be between 25 and 45 micron, for example equivalent to the radius of curvature in the center of the lenses of the lenticular array. Therefore, the thickness of the security element as well obtained is about 30 microns which is particularly suitable for integration in a fine security document such as a banknote. In addition, the lens diameter of 30 microns induces a totally satisfactory pattern resolution for authentication and identification. Finally, the inscription of a pattern element covering a surface corresponding to about half of the surface of a lens implies a pattern element width of about 15 microns which makes it possible to overcome the processes of complex and expensive registration such as those made by means of a laser for very high resolutions, for example for the printing of a complete pattern behind each lens as in the case of a magnifying moiré effect.

The pattern may be formed on the security element by metallization and / or demetallization, for example aluminum. The metallization / demetallization processes have a fineness and a definition such that they are difficult to reproduce by printing, which thus makes it possible to avoid counterfeiting by printing. However, the pattern can be registered by a printing process such as offset, intaglio, laser, inkjet, microlithography, gravure or screen printing. It is understood that the reason can be written in positive or in negative. The pattern may also be formed by dots having optical diffraction properties of the light which are arranged on a mirror reflecting surface so as to have a high contrast with respect to the surface. The points constituting the pattern may be achromatic, that is, they do not break down white light, and be arranged on a non-achromatic surface.

Alternatively, the pattern can be printed with colored or non-colored inks, visible to the naked eye or not, for example inks only visible under ultraviolet or infrared light, opaque, fluorescent, phosphorescent, thermochromic, photochromic, translucent and / or transparent In the case of visible printing, the light source used to illuminate the optical structure is, for example, ambient light from the sun or artificial light. In the case of an ink revealed under excitation by a given wavelength the appropriate lighting device will be used. According to another embodiment, the invention may have the following features:

the reflective or at least partially opaque or semi-reflective surface is metallic,

said first and / or second patterns are printed on the reflective or at least partially opaque or semi-reflective surface.

According to another particular embodiment, the security element according to the invention comprises an adhesive, in particular a heat-sealable varnish, the adhesive being carried by each face of the security element. Alternatively, the adhesive can be worn on one side.

According to another particular embodiment of the invention, the face of the substrate equipped with the optical structure comprises an adhesive on areas of this face which are not covered by the optical structure, the optical structure being devoid of adhesive on its surface. . Advantageously, the presence of the adhesive only in areas of the substrate not covered by the optical structure may make it possible not to affect the optical properties of the structure. In addition, the security element may be elongated and have edges covered with an adhesive, including a varnish or a heat-sealable resin. In the case of a security element of elongated shape, for example in the form of a security thread, the optical structure may extend only partially over the width of the security thread so that the substrate of the security thread has at least an edge area not covered by the optical structure and on which an adhesive can be provided. This edge zone may also be covered with a pattern, for example the same pattern as previously described. The edge zone may be discontinuous or continuous and extend from one edge to the other along the security element to provide adhesion along the security element. As a result, the adhesive and the edge zone serve to enhance the cohesion between the security element and an object, for example a security document, in which it is incorporated.

For example, the distance between two edge areas of the security element is between 2 and 9 mm and the width of the edge zone can be between 0.5 and 2mm. The security element has a width of approximately 2 to 10 mm.

The adhesive may be transparent, translucent or opaque. The adhesive can be heat sealable. The adhesive may be colorless or colored, visible to the naked eye, under ultraviolet (UV) and / or infrared (IR), fluorescent, phosphorescent, thermochromic, photochromic, among others. The adhesive may for example be a heat-sealing coating, for example a heat-sealing varnish, an ultraviolet (UV) cross-linkable agent, an adhesive to be irradiated, a pressure-sensitive adhesive (PSA), a varnish with a solvent base, of the type polyester, for example, an aqueous phase adhesive, etc. The adhesive may advantageously be an adhesive based on polyvinyl acetate. The incorporation of the adhesive into the security element can be by coating or printing.

Areas that are not covered by the optical structure may also include a magnetic code. For example, the magnetic code consists of disjoint elements comprising magnetic particles. The elements can be applied by selective printing of an ink containing magnetic particles.

The magnetic code thus constituted has a particular magnetic response which makes it possible to authenticate the security document carrying the security element. Advantageously, this magnetic code can be masked optically by an opaque layer. In a particular embodiment, the adhesive may constitute the opaque layer. As a result, the presence of the code can not be detected visually but only by means of a suitable reading device.

The magnetic particles can also be mixed with the adhesive. During the encoding process, these particles are magnetized in the direction of the north or south pole. The polarity of the magnetic particles is changed to define bits forming a magnetic code.

The invention extends to a security support consisting of natural fibrous materials, for example cellulose and / or cotton, and / or synthetic fibers, which comprises at least one security element as described above. In particular, the security element is in the form of a wire which is at least partially integrated into the support of security. For example, the security element is embedded in windows in a security document so that the same pattern can be observed at the first and second positions at least through the window.

Alternatively, the security element is in the form of a band or a patch applied on a surface of the support.

The invention extends to a security document such as a passport, an identity card, a driving license, a playing card or interactive collectible card, a means of payment, including a payment card, a ticket bank card, voucher, voucher, transport card, loyalty card, service card or membership card, including the security element or security support described above.

The invention also extends to a method for authenticating or identifying a security document, in which information concerning the identity or authenticity of the security document is determined by observing the first and the second reason at least partially identical, the first pattern being observable through the optical structure at a first angle of observation at a first position on the second face, the second pattern being observable through the optical structure at a second angle of observation, different from the first angle, to a second position on the second face different from the first position.

An exemplary embodiment is described in more detail below and illustrated by the figures. This description is given as an indicative and non-limiting example of the invention.

Figure 1a schematically illustrates a security element according to the invention in cross section with a first viewing angle.

Figure 1b schematically illustrates a security element according to the invention in cross section with a second viewing angle.

Figures 2a and 2b schematically illustrate the details of a security element according to the invention seen from the front.

Figure 3a schematically illustrates a security element according to the invention seen from the front according to the first viewing angle. Figure 3b schematically illustrates a security element according to the invention seen from the front according to the second viewing angle.

Figure 4 schematically illustrates a security document comprising a security element according to the invention.

FIGS. 1 a and 1 b show a security element 1 according to the invention comprising a substrate 2 provided with a first face 3 and a second face 4.

The first face 3 of the substrate 2 is equipped with an optical structure 5. While on the second face 4 at least a first 6 and a second 7 pattern are respectively registered at a first position 8 and at a second position 9 on this second face 4.

The optical structure 5 is composed of a lenticular network comprising a set of lenses 10 which are for example cylindrical or hemispherical, concave, convex or Fresnel and are arranged in a hexagonal, hexagonal compact or rectangular arrangement.

In the detail of Figures 2a and 2b, it is shown that the lenticular array 5 consists of a set of hemispherical lenses 1 0 which are arranged coplanar on the first face 3 and arranged in rows or staggered columns. For example, the lenticular array is formed of a plurality of lenses 10 disposed adjacent each other to form a contiguous lens column. This lens column is itself adjacent to another lens column 10, the lens columns 10 themselves being arranged offset from one another, for example with a shift of about one hemispherical lens radius. in a direction along the lens column 10. This staggered arrangement of the lenses allows optimal compaction of the lenses 10 on the first face 3 of the substrate 2, which has the effect of increasing the overall resolution of the pattern for a higher level of authentication. effective of the security element.

Alternatively, the lenses 10 may be hexagonal in shape and arranged in a distribution corresponding to a "honeycomb". The lenses 10 may further be of cylindrical shape and arranged juxtaposed to one another. The lenticular network of the optical structure 5 illustrated in FIGS. 1a and 1b shows a cross-sectional section of the security element along an axis A (illustrated in FIGS. 3a and 3b) corresponding to a line of lenses 10 of FIGS. FIGS. 2a and 2b which pass through the center of the hemispherical lenses of said lens line 10. For the sake of clarity, the first 6 and the second pattern 7 inscribed on the second face of the substrate 2 as illustrated in FIGS. and 1b do not correspond exactly to the first 6 and second pattern 7 illustrated in Figures 2a and 2b. FIGS. 1a and 1b schematically illustrate the first 6 and second 7 patterns which are respectively written at a first position 8 and at a second position 9 on the second face 4, respectively to the right and to the left of the element 1 on the embodiment of Figures 1 to 3.

Moreover, FIGS. 1a, 1b, 2a and 2b are intended to show that, according to the invention, the first 6 and the second pattern 7 consist of a set of disjoint pattern elements, respectively called after the first 11 and second 12 pattern elements. Each pattern thus has a "pixelated" appearance.

Advantageously, the elements of patterns 1 1 and 12 constituting together respectively the first 6 and second 7 pattern are inscribed on the second face 2 in the manner of a "raster pattern".

It is necessary to give the term "raster pattern" a broad meaning that covers all types of frames or pseudo-frames, the shape of the elements of pattern 1 1 and 12 not being limited to a particular shape but may be arbitrary.

A simple halftone pattern corresponds to a semitone pattern or a binary pattern, that is to say that the shades of the pattern are two in number, for example black and white, or in the case of a selective metallization of the second face 4 of the substrate 2, the two shades of the image are in a first zone metallization and in a second zone the absence of metallization.

Furthermore, a more complex, that is to say multitone, raster pattern can for example be obtained by a framing method by frequency modulation or amplitude modulation. According to these respective methods the size weft points vary according to the optical density to be reproduced or the size of the points of the frame is constant but the spacing varies according to the optical density to be reproduced. A pattern having a three-dimensional printing effect is thus feasible.

In Figure 2a, there is shown enlarged letter "A" corresponding to a portion of the second pattern 7 "AWS" inscribed on the second side 4 and shown on the left in Figure 3b. The letter "A" of the second pattern 7 "AWS" consists of a second set of disjoint pattern elements 12 which are each arranged opposite a corresponding lens 10. In the example of FIG. 2a, it is shown that the second pattern elements 12 are constituted by circular-shaped dots having for example a diameter of about 15 microns and arranged on one side with respect to the center of the corresponding lens. on the left in the embodiment of FIG. 2a.

In the same way, in FIG. 2b, the letter "A" corresponding to the first pattern "AWS" inscribed on the second face 4 and illustrated on the right in FIG. 3a is enlarged.

The letter "A" of the first pattern 7 "AWS" consists of a first set of disjoint pattern elements 1 1 which are each arranged opposite a corresponding lens 10. In the example of FIG. 2b, it is shown that the first elements of pattern 1 1 are constituted by circular-shaped dots having for example a diameter of about 15 microns and arranged on the opposite side with respect to the center of the corresponding lens, right in the embodiment of Figure 2b.

According to the invention, each pattern element 11 and 12 is arranged facing a corresponding lens 10. In addition, at said first position 8 each first pattern element 11 is disposed on a first side relative to the center of the corresponding lens, that is to say with respect to the center of the lens opposite which it is willing. At said second position 9 each second pattern element 12 is arranged on a second side with respect to the center of the corresponding lens, that is to say with respect to the center of the lens opposite which it is arranged. The first side is opposite the second side with respect to the center of the lenses. Although the first 11 and second 12 pattern elements are each arranged opposite different lenses, it is understood that, on the axis A passing through the centers of the lenses forming a line, if each first pattern element 11 is arranged a first side with respect to the center of the corresponding lens, for example on the right in the embodiment of the figures, the second pattern element 12 is then arranged on a second side with respect to the center of the corresponding lens which is diametrically opposed to the first side, left in the embodiment.

Accordingly, in the case of a hemispherical lens array the first and second sides are diametrically opposed. In the case of cylindrical lenses, the first and second sides are axially opposite, that is to say arranged on opposite sides with respect to the axis of the lens.

Preferably, each pattern element 11 or 12 is inscribed on the second face 4 opposite a corresponding lens so as to cover a surface whose width along the axis A is approximately equivalent to the radius of the corresponding lens 10, for example 15 microns.

Furthermore, according to the invention, the distance between the lenticular network 5 and the first 6 or the second pattern 7 is less than or equal to the focal length of the lenses 10 of the lenticular array. In addition, according to the invention, the distance between the lenticular network 5 and the inscribed pattern 6 or 7 is preferably greater than or equal to the radius of curvature in the center of the lenses 10 of the lenticular array 5. The distance between the lenticular array and the inscribed pattern being understood as the distance between the top of the lenses of the lenticular array and the inscribed pattern or between the top of the lenses of the lenticular array and the second face 4 of the substrate 2.

Advantageously, the surface covered by the pattern elements 1 1 or 12 relative to the corresponding lens and the distance between these pattern elements and the lenticular network 5 makes it possible to obtain in a simple manner a thin security element which can be integrated into a security document such as a bank note. In addition, with this arrangement the pattern elements 11 and 12 observed through the lenses 10 of the optical structure 5 are enlarged and each cover the entire apparent surface of the corresponding lens so that the first 6 and second pattern 7 appear substantially unframed.

This arrangement makes it possible to alternately make appear and disappear the first pattern 6 and the second pattern 7 in a particularly suitable manner for the authentication and / or the identification of the security element 1.

Indeed, with a security element according to the invention as described above, when the observer 13 varies its viewing angle along the axis A for example left at an angle a1 to the right at an angle a2 in the 3a and 3b, it first observes the first pattern at the first position as illustrated in Figure 3a and then observes the second pattern at the second position as illustrated in Figure 3b. The first and the second pattern being substantially identical appearance and disappearance at different positions of the same pattern is an optical effect easily recognizable for authentication and / or identification simple and immediate.

In addition, it can be expected that the pattern elements are obtained by metallization or demetallization which enhances the contrast effect between appearance and disappearance and further facilitates the recognition and authentication of the element. security.

It can also be provided that the pattern elements are printed on the second face 4 of the substrate 2 and then covered with a reflective or semi-reflective layer. In addition, another printing can be performed on the semi-reflecting layer so as to reveal another pattern that would be visible only in transmitted light for example.

To further facilitate the authentication and / or identification, the security element 1 may comprise other identical patterns arranged in the same manner as above but at different positions as shown in Figures 3a and 3b.

In a particular embodiment of the invention, the first face 3 of the substrate 2 is not completely covered by the optical structure 5. In particular the edge zones or lateral zones 14 of the first face 3 are free of lenses 10 and can receive third 15 and fourth reference pattern at least partially identical to the first and second patterns.

For example, the third pattern 15 is disposed in a lateral zone 14 near the first pattern 6 so as to constitute a comparison pattern with the latter. Since the third pattern 15 is located outside the optical structure, its appearance is fixed, that is to say that it does not vary as a function of the angle of observation, thus facilitating recognition and identification of the first pattern. 6 that appears and disappears. Similarly, the fourth pattern 16 is advantageously arranged in a lateral zone 14 near the second pattern 7 in order to serve as a comparison element.

The third and fourth patterns can be obtained by selective impressions, positive or negative, perforations, deposits and / or voids of materials.

It can also be provided that the security element according to the invention comprises an adhesive 17, in particular a varnish or a heat-sealable resin. The adhesive 17 may be carried by the lateral zones 14 and / or by the second face 4 of the substrate 2. Advantageously, an adhesive 17 carried by the two faces 3 and 4 of the support 2 optimally reinforces the cohesion between the element Security 1 and the security document in which it is incorporated. Preferably, the side area 14 and the adhesive 17 extend along the security element 1 so as to ensure complete cohesion of the security element in the document.

The security element may be incorporated at least partially en masse in the security document, and only a part appears visible, for example, through a plurality of windows formed in the forming fibrous mass as described in EP59056.

As illustrated in FIG. 4, when the security element is incorporated into windows 18 in a cellulosic support 19 for example to form a security document 20, the windows can advantageously allow the simultaneous observation of at least the first and second windows. pattern 6 and 7 and at least a portion of the third and fourth reference patterns. Alternatively, the security element is deposited on the surface of the security document forming an extra thickness or in an elongate cavity provided to accommodate the element without generating extra thickness.

Finally, the security element may be in the form of a patch 21 which is deposited on the surface of the security document.

Preferably, the security document incorporating the security element consists of natural fibrous materials, for example cellulose and / or cotton, and / or synthetic fibers. The security support can also be made from plastic materials such as a PolyartTM film sold by the company ARJOBEX Ltd ..

The security document including the support and the security element may be a document such as a passport, an identity card, a driving license, a playing card or interactive collectible card, a means of payment, including a credit card, voucher, voucher, transport card, loyalty card, service card or membership card.

A security document thus obtained therefore comprises at least one security element as described above which constitutes a so-called "first level" security element. However, it may include other "first level" security elements and / or at least one so-called "second level" and / or "third level" security element.

The document may in particular comprise the following security elements alone or in combination:

dyes and / or luminescent pigments and / or interferential pigments and / or liquid crystal pigments, in particular in printed form or mixed with at least one constituent layer of the document,

components, dyes and / or photochromic or thermochromic pigments, in particular in printed form or mixed with at least one constituent layer of the document,

an ultraviolet (UV) absorber, in particular in the form coated or mixed with at least one constituent layer of the document,

a specific light-collecting material, for example of the "waveguide" type, for example a light-collecting material as the polycarbonate-based polymer films marketed by Bayer under the name LISA®,

an interference multilayer film,

a structure with variable optical effects based on interferential pigments or liquid crystals,

a birefringent or polarizing layer,

a diffraction structure,

- an embossed image,

means producing a "moiré effect", such an effect being able for example to reveal a pattern produced by the superposition of two security elements on the document, for example by bringing lines of two security elements closer together,

a partially reflective refractive element,

- a colored filter.

another foil metallized, goniochromatic or holographic,

a layer with a variable optical effect based on interferential pigments or on liquid crystals,

a flat and relatively small security element such as a board, visible or non-visible, in particular a luminescent board, with or without an electronic device,

particles or agglomerates of pigment particles or dyes of the HI-LITE type, visible or non-visible, in particular luminescent,

- security fibers, in particular metallic, magnetic (with soft magnetism and / or hard), or absorbing, or excitable with ultraviolet, the visible or the infrared, and in particular the near infrared (NIR),

an automatically readable security having specific and measurable characteristics of luminescence (for example fluorescence, phosphorescence), light absorption (for example ultraviolet, visible or infrared), Raman activity, magnetism, microwave interaction, X-ray interaction or electrical conductivity.

One or more security elements as defined above may be present in the document and / or in one or more constituent layers of the document or in one or more security elements embedded in the document and / or one or more constituent layers of the document, such as a wire, a fiber or a board.

At least one of the constituent layers of the document may also include a first level security element such as a watermark or a pseudo-watermark superimposed at least partially on a translucent region of the document.

It is understood that the expression "comprising a" or "comprising a" is synonymous with "comprising at least one" or "comprising at least one", unless the opposite is specified.

Claims

1. Security element (1) comprising a substrate (2) provided with a first face (3) equipped with an optical structure (5) and a second face (4), characterized in that it comprises at least one first (6) and a second pattern (7) inscribed on the second face of the substrate, the first pattern (6) being observable through the optical structure (5) at a first angle (a1) of observation at a first position ( 8) on the second face, the second pattern (7) being observable through the optical structure (5) at a second viewing angle (a2), different from the first angle (a1), at a second position (9) on the second face (4) different from the first position (8), the first (6) and the second pattern (7) being at least partially identical.

The security element of claim 1, wherein a reflective or at least partially opaque or semi-reflective surface is observable at the first position (8) at the second viewing angle (a2) and / or at the second position (9) under the first angle of observation (a1).

3. Security element according to one of claims 1 or 2, wherein the optical structure (5) is composed of a lenticular array comprising a set of lenses (10).

4. Security element according to claim 3, wherein the distance between the optical structure (5) and the first (6) or second (7) registered pattern is less than or equal to the focal length of the lenses (10) of the network. lenticular.

5. Security element according to one of claims 3 or 4, wherein the distance between the optical structure (5) and the first (6) or the second (7) registered pattern is greater than or equal to the radius of curvature in the center lenses of the lenticular network.

6. Security element according to one of claims 3 to 5, wherein the lenses (10) of the lenticular array are cylindrical or hemispherical.

7. Security element according to one of claims 3 to 6, wherein the lenticular array consists of coplanar hemispherical lenses arranged staggered, hexagonal lenses arranged in "honeycomb" or juxtaposed cylindrical lenses.

Security element according to one of claims 2 to 6, characterized in that the first (6) and second (7) patterns consist of a set of disjoint pattern elements (1 1, 12), each pattern element being arranged facing a corresponding lens, and in that said first position (8) each pattern element is arranged on a first side with respect to the center or the axis of said corresponding lens, and each pattern element at said second position (9) is arranged on a second side, opposite the first side, with respect to the center or axis of said corresponding lens.

9. Security element according to one of claims 2 to 8, wherein the reflective surface or at least partially opaque or semi-reflective is metallic.

10. Security element according to one of claims 2 to 9, wherein said first (6) and / or second (7) pattern is printed on the reflective surface or at least partially opaque or semi-reflective.

1 1. Security element according to one of the preceding claims, characterized in that it comprises an adhesive (17), in particular a heat-sealable varnish, the adhesive being carried by each face of the security element.

12. Security element according to one of the preceding claims, the face of the substrate (2) equipped with the optical structure (5) comprises an adhesive (17) on areas of this face which are not covered by the optical structure, the optical structure being free of adhesive on its surface.

13. Security element according to claim 12, characterized in that the security element is elongated and has edges (14) covered with an adhesive (17), in particular a heat-sealable varnish.

14. Security element according to one of the preceding claims, characterized in that it comprises disjoint magnetic elements forming a magnetic code.

15. Security element according to claim 14, comprising in an area of the magnetic code at least two magnetic materials having strong and different coercivities but arranged in or on the security element so as to have substantially equal remanence.

16. The security element as claimed in claim 14, the security element comprising a weakly coercive magnetic zone at least partially covered by a highly coercive magnetic zone which magnetizes the weakly coercive magnetic zone.

17. Safety support consisting of natural fibrous materials, for example cellulose and / or cotton, and / or synthetic fibers, characterized in that it comprises at least one security element according to one of the preceding claims.

18. Safety support (19) according to the preceding claim, wherein the security element (1) is in the form of a wire which is at least partially integrated into the safety support.

19. Safety support according to claim 17, wherein the security element is in the form of a strip or a patch (21) applied to a surface of the support (19).

20. Security security document (20) such as a passport, an identity card, a driving license, an interactive playing or collectible card, a means of payment, in particular a payment card, a ticket of bank, purchase certificate or voucher, transport card, loyalty card, service card or subscription card, including a security element (1) according to any one of claims 1 to 16 or a security support (19) according to any one of claims 17 to 19.

21. A method of authenticating or identifying a security document (20) according to claim 17, wherein information regarding the identity or authenticity of the security document is determined by observing the first (6) and second (7) at least partially identical pattern, the first pattern (6) being observed through the optical structure (5) at a first viewing angle (a1) at a first position (8) on the second face (4), and the second pattern (7) being observed through the optical structure (5) at a second angle of observation (a2), different from the first angle, at a second position (9) on the second face different from the first position ( 8).