Security structure

Abstract

The present disclosure relates to a security structure including a non-opaque, preferably transparent, substrate. The substrate supports metal elements forming a revealing pattern. The metal is thin enough for the metal to be non-opaque. A lacquer is placed at least partially, preferably exactly, on top of the metal elements. The lacquer may be in contact with the metal elements.

Claims

1. A security structure, comprising: a non-opaque carrier; metal elements borne by the carrier and forming a revealing pattern, a thickness of each of the metal elements being sufficiently small so that the metal elements are not opaque; a lacquer at least partially superposed on the metal elements, the lacquer making contact with the metal elements; and an element to be revealed superposed on the revealing pattern, the element to be revealed being incorporated by construction in the security structure and comprising a plurality of interleaved images, the revealing pattern allowing the plurality of interleaved images to appear in succession when a direction of observation changes.

2. The structure as claimed in claim 1, the lacquer comprising a first composition covering a first zone of the metal elements and a second composition, different from the first composition, covering a second zone of the metal elements.

3. The structure as claimed in claim 2, one of the first and second compositions being transparent.

4. The structure as claimed in claim 2, at least one of the first and second compositions being applied so as to produce a pattern visible to a naked eye in transmitted light.

5. The structure as claimed in claim 1, the element to be revealed and the revealing pattern being arranged on either side of the carrier.

6. A secured article comprising a security structure as defined in claim 1.

7. The article as claimed in claim 6, comprising information viewable using the revealing pattern.

8. The article as claimed in claim 6, the security structure being incorporated in windows of the article.

9. A method for manufacturing a security structure according to claim 1, comprising: depositing, by printing, the lacquer so as to form a design of the revealing pattern; and forming patterned metal elements.

10. The method as claimed in claim 9, the patterned metal elements being produced by etching a metal layer covering the carrier and covered by the lacquer.

11. The method as claimed in claim 9, the lacquer being deposited in a form of two prints of different compositions.

12. A method for authenticating or identifying a secured article as defined in claim 7, further comprising authenticating or identifying the secured article based on an optical effect obtained in response to superposition of the revealing pattern on the information.

13. The structure as claimed in claim 1, wherein the carrier is transparent.

14. The structure as claimed in claim 1, wherein the lacquer is exactly superposed on the metal elements.

15. The structure as claimed in claim 1, wherein the lacquer makes contact with the metal elements.

16. The structure of claim 2, wherein the second composition is of different color and opacity than the first composition.

17. The structure of claim 2, wherein the first and second compositions do not overlap.

18. The structure as claimed in claim 1, the element to be revealed being produced by printing.

19. A security structure, comprising: a non-opaque carrier; metal elements borne by the carrier and forming a revealing pattern, a thickness of each of the metal elements being sufficiently small so that the metal elements are not opaque; a lacquer at least partially superposed on the metal elements, the lacquer covering the metal elements on a side opposite to the carrier; and an element to be revealed superposed on the revealing pattern, the element to be revealed being incorporated by construction in the security structure and comprising a plurality of interleaved images, the revealing pattern allowing the plurality of interleaved images to appear in succession when a direction of observation changes.

20. The structure as claimed in claim 19, the lacquer being non-transparent.

21. The structure as claimed in claim 19, the element to be revealed being produced by printing.

22. A security structure, comprising: a non-opaque carrier; metal elements borne by the carrier and forming a revealing pattern, a thickness of each of the metal element being sufficiently small so that the metal elements are not opaque; a lacquer at least partially superposed on the metal elements, the lacquer making contact with the metal elements, the lacquer being interposed between the metal elements and the carrier in a direction perpendicular to a main plane of the security structure; and an element to be revealed superposed on the revealing pattern, the element to be revealed comprising a plurality of interleaved images, the revealing pattern allowing the plurality of interleaved images to appear in succession when a direction of observation changes.

23. The structure as claimed in claim 22, the lacquer being transparent but colored.

24. The structure as claimed in claim 20, wherein the lacquer is opaque.

25. A secured article comprising an element to be revealed and a security structure to superpose on the element to be revealed, the security structure comprising: a non-opaque carrier; metal elements borne by the carrier and forming a revealing pattern, a thickness of each of the metal elements being sufficiently small so that the metal elements are not opaque; and a lacquer at least partially superposed on the metal elements, wherein the element to be revealed comprises a plurality of interleaved images, the revealing pattern allowing the interleaved images to appear individually in succession upon a relative movement between the revealing pattern and the element to be revealed, and wherein the element to be revealed being added to the secured article by a printing process.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The various exemplary embodiments described herein will be better understood on reading the following detailed description of nonlimiting embodiments thereof and on examining the appended drawings, in which:

(2) FIG. 1 shows a security document comprising a security structure, according to an exemplary embodiment, and an element to be revealed, associated with the security structure;

(3) FIG. 2 shows in isolation the element to be revealed, according to an exemplary embodiment;

(4) FIG. 3 schematically shows in isolation the revealing pattern, according to an exemplary embodiment;

(5) FIG. 3A shows a detail of FIG. 3;

(6) FIG. 4 shows the coded images of the combined image corresponding to the element to be revealed in FIG. 2, according to an exemplary embodiment;

(7) FIG. 5 schematically and partially shows in cross section the security structure bearing the revealing pattern in FIG. 3, according to an exemplary embodiment;

(8) FIG. 7 is an analogous view to FIG. 5 of the security structure, according to an exemplary embodiment;

(9) FIG. 6 shows the structure in FIG. 7, before demetallization, according to an exemplary embodiment;

(10) FIG. 8 shows a variant revealing pattern, according to an exemplary embodiment;

(11) FIG. 9 is an analogous view to FIG. 6 of an exemplary embodiment of the security structure;

(12) FIG. 10 shows an example article incorporating a security structure produced, according to an exemplary embodiment;

(13) FIG. 11 is a schematic cross-sectional view of another security structure, according to an exemplary embodiment, in which the element to be revealed and the revealing pattern are superposed by construction; and

(14) FIG. 12 shows a revealing pattern equipped with an additional security element, according to an exemplary embodiment.

DETAILED DESCRIPTION

(15) FIG. 1 shows an example security document 10 such as a banknote. The following applies to other articles.

(16) This document 10 comprises a substrate 11, for example made of paper, that incorporates a security structure 20, according to an exemplary embodiment.

(17) The document 10 also comprises an element to be revealed 30, for example comprising at least one coded image made visible by virtue of the security structure 20 when the latter is superposed on the element to be revealed 30.

(18) The document 10 may be authenticated by folding the document so as to at least partially superpose the element to be revealed 30 and the revealing pattern 20 and then moving them relative to each other so as to, for example, view the illusion of a movement and/or to modify the angle of observation of the superposed element to be revealed and revealing pattern. According to an exemplary embodiment, the element to be revealed and the revealing means are superposed so as to make contact.

(19) The observation may be carried out in reflected light, the observer viewing the combined image and the revealing screen in reflection under illumination from a light source.

(20) According to an exemplary embodiment, it may also be possible to superpose at least partially the document 10 with another similar document.

(21) FIG. 4 shows a series 2a of the interleaved images I.sub.i, . . . I.sub.j, where j is for example equal to four, allowing a combined image 2 of the element to be revealed 30 to be created representing, in this example, a pattern taking the form of an elephant.

(22) The interleaved images I.sub.i, . . . I.sub.j, for example correspond to four different positions of the elephant and thus allow a decomposition of the movement of the elephant to be created. Each interleaved image 2a comprises a set of parallel lines.

(23) FIG. 2 shows the combined image obtained from the series of interleaved images 2a in FIG. 4, as it figures on the element to be revealed 30.

(24) All the constituent elements of a given coded image may be arranged with the same period p as the opacifying lines of the revealing screen, along the axis X of movement, perpendicular to the lines.

(25) The images 2a are superposed on one another so as to form a combined pattern that corresponds to the combined image.

(26) FIG. 3 shows the revealing pattern 20 taking the form of a revealing screen associated with the combined image in FIG. 2.

(27) The revealing pattern 20 is, for example, composed of a periodic elementary feature, in the present case an opacifying line, of constant period p, as illustrated in FIG. 3A.

(28) The revealing pattern 20 is, for example, rectangular in shape.

(29) The revealing pattern 20 has an area, a length and a width that may be larger than those of the combined image, thus allowing all of the movements of the elephant to be viewed more easily during the relative movement of the element to be revealed 30 and the revealing pattern 20, such as via a relative translational movement or change of angle of observation.

(30) FIG. 5 shows the security structure 20. The latter comprises a carrier 21, for example, made of transparent PET, covered on one face by a metalized layer 22, itself covered with a lacquer 23. The metalized layer 22 is of low optical density. The lacquer 23 is, for example, black in color.

(31) The metal is preferably aluminum. Preferably, the observation is carried out from the verso, i.e. from the lower face 21a in FIG. 5, so as to protect the features and observe the metallic appearance. Depending on the way in which the incorporation into the substrate is carried out, the recto may be observable, the metallic/nonmetallic difference in aspect of the recto/verso providing an additional security feature.

(32) The lacquer 23 on the metalized layer increases the opacity, so as to allow the element to be revealed 30 to be authenticated.

(33) To produce the security structure 20, the carrier 21 may be uniformly metalized, according to an exemplary embodiment. Next, the lacquer 23 is deposited, for example by printing, with the revealing pattern to be produced. The metal zones not protected by the lacquer 23 are removed.

(34) By way of example, FIG. 9 shows a security structure in which the carrier 21 has been metalized and then selectively demetalized by chemical action.

(35) Although it is preferable to produce the revealing pattern by depositing the lacquer on the metalized carrier, the revealing pattern may be produced by metalizing a carrier on which a primer has been deposited with the negative of the pattern to be produced, according to an exemplary embodiment.

(36) The metal may be selectively removed by chemical action using a solvent that dissolves the primer, according to an exemplary embodiment. By way of example of processes allowing metal elements to be produced with the desired pattern, mention may be made of WO 99/13157, EP 1 291 463 and WO 02/31214, among other documents. Reference may also be made to the prior art cited in these documents.

(37) Comparative Trials

(38) The table below gives gloss measurements at an incidence of 20 for unapertured metalized films and then after production of the screens. The optical density is measured before demetallization.

(39) The values of 158, 200 or 400 m correspond to the period of the screen.

(40) TABLE-US-00001 Partially Partially Partially demetalized film: demetalized film: demetalized film: Metalized film 158 m screen 200 m screen 400 m screen Low OD High OD Low High Low High Low High (0.7) (2.2) OD OD OD OD OD OD Lacquer No No Colored Colored Colored Colored Colored Colored Gloss at 210 361 175 365 165 246 133 198 20

(41) The gloss was measured according to the 3rd part of standard ISO 8254, such as at 20.

(42) The metalized film was a polyester film covered with an aluminum layer, of different thicknesses corresponding to the optical densities. The metal films of low and high optical densities correspond for example to metal thicknesses of about 50 and about 300 , respectively.

(43) The measurements confirm the lower gloss of low optical density films relative to high optical density films. When a screen is present, the tendency is the same.

(44) To evaluate how effective a colored lacquer was at opacifying the screen, measurements were carried out on high and low optical density metalized films before and after printing of the lacquer. The results are given in the table below:

(45) TABLE-US-00002 Non-demetalized Non-demetalized Non-demetalized Opacity film: printed film: printed film: printed (white Metalized film 158 m screen 200 m screen 400 m screen background) Low OD High OD Low OD High OD Low OD High OD Low OD High OD 24 85 76 95 77 93 69 89

(46) The opacity on white background was measured according to standard ISO 2471.

(47) Application of the colored lacquer allowed the low optical density film to be considerably opacified. The opacity obtained is then close to that of the high optical density film before printing.

(48) Images having a plurality of tones may be produced on the revealing pattern using lacquers of different opacities on the elementary features.

(49) For this purpose, referring to FIGS. 6 and 7, a transparent protective lacquer 23a may be applied to zones 26 of the metalized film 22, and a colored protective lacquer 23b to zones 25, the intermediate zones 27 being unprotected, as illustrated in FIG. 6, before demetallization.

(50) After demetallization, as illustrated in FIG. 7, the zones 27 are transparent, the zones 26 semi-opaque and the zones 25 a little more opaque. In transmitted light, a pattern appears, related to the contrast between the zones 25 and 26, which pattern was less visible in reflected light or even not visible in reflected light.

(51) Incorporation into One or More Windows

(52) Advantageously, the security structure figures in at least one window of the secured article, such as of the security document, such as in the case in the example in FIG. 1.

(53) The window may be formed by a lack of material, for example a local absence of paper, above or below the security structure, the window being at least partially transparent or translucent on the side of the security structure opposite the lack of material. Thus, it may be possible to observe a first side of the security structure on the side of the lack of material and a second side of the security structure, opposite the first, on the side of the transparent or translucent zone of the window.

(54) The window may even not comprise a lack of material. The window may, for example, be at least partially transparent or translucent on either side of the security structure, the transparent or translucent zones being superposed on each other in order to allow the two opposite sides of the security structure to be observed.

(55) The window may even be a through-window. The window may be present due to a lack of material superposed on either side of the security structure. The two sides of the security structure may thus be observable directly and not through transparent or translucent zones. The security structure may be completely or partially incorporated in the window.

(56) The article may comprise a plurality of windows, such as described in the exemplary embodiments herein.

(57) Examples of production of windows in security documents are, for example, described in GB 1 552 853, which discloses the creation of a window especially by transparentisation, laser cutting, abrasion or mechanical incision; in EP 0 229 645, which describes the creation, using masks, of a window in one face or in both faces of a two-ply paper; in WO 2004/096482, which describes the creation of a window by laser cutting; in CA 2 471 379, which describes the creation of a transparent window and association with a security element; and in WO 2008/006983, which describes the creation of a transparent window in a two-ply paper.

(58) FIG. 10 shows an incorporation into windows in a fibrous substrate when the security structure 20 takes the form of a security thread that extends from one edge to the other of the document, according to an exemplary embodiment. The revealing pattern, for example, appears in zones of the document in which the thread is flush with the surface of the fibrous substrate.

(59) The document may comprise a plurality of such zones.

(60) In the case of an incorporation into windows of a security structure taking the form of a security thread, said structure may incorporate by construction the element to be revealed, and, for example, have the arrangement shown in FIG. 11, which is described below.

(61) Production of the Element to be Revealed

(62) The element to be revealed may be added to the secured article by a printing process, for example offset printing, gravure printing, laser printing, rotogravure printing or screen printing. For example, the element to be revealed is printed with optionally metallic, optionally magnetic inks that are optionally colored, visible to the naked eye, under ultraviolet (UV) and/or infrared (IR) light, opaque or luminescent, especially fluorescent, thermochromic or photochromic or that produce an interference effect, especially an iridescence, or an optical effect that varies depending on the angle of observation (gonochromatic) and especially inks comprising liquid crystals, inter alia. When a magnetic ink is used, the pattern may form a magnetic signature allowing additional authentication of the substrate via detection of said signature. The element to be revealed 30 may also comprise metallizations and/or demetallizations, for example made of aluminum.

(63) When the element to be revealed is at least partially produced with at least one thermochromic and/or photochromic ink, only some of the element to be revealed is for example to be observable under preset illumination and/or temperature conditions.

(64) The element to be revealed may even be printed with liquid crystals, such that for example the coded images are visible only through a polarizer. These may in particular be nematic liquid crystals.

(65) The element to be revealed may be a watermark or a pseudo-watermark.

(66) The revealing pattern and/or the element to be revealed may be monochromatic or polychromatic.

(67) The element to be revealed and/or the revealing pattern may be produced with different colors.

(68) The use of color to produce the element to be revealed may allow the security of the article to be further increased.

(69) The element to be revealed may be incorporated by construction in the security structure, for example by being produced on that face of the carrier 21 which is opposite the face bearing the revealing pattern, as illustrated in the exemplary embodiment of FIG. 11.

(70) When the angle of observation a varies, the user may see appear in succession the various interleaved images, which, in the example of the present case, are four in number I.sub.1, . . . I.sub.4.

(71) Exemplary Revealing Patterns

(72) The security structure may comprise two revealing patterns, according to an exemplary embodiment, for example, taking the form of screens, associated with two elements to be revealed, respectively, the orientation of the lines of one of the revealing screens being different from those of the other revealing screen. When the lines are not rectilinear, their orientation is defined by the general direction in which they extend.

(73) The security structure may comprise two revealing screens, whether juxtaposed or not or superposed or not, comprising lines which may or may not have the same orientation. One of the revealing screens may be completely or partially encircled by the other revealing screen. An optional zone of superposition of the revealing screens may cause a sort of grid pattern to appear if the strips of the revealing screens have different orientations.

(74) The revealing screen may comprise other features than strips of constant width having rectilinear parallel edges, such as, for example, crenellations or undulations, such as illustrated in the exemplary embodiment of FIG. 8.

(75) According to an exemplary embodiment, two combined images of different sizes are associated. The smaller combined image may be repeated, such as to form an array, which may be in rows and columns, in order to appear as a background on which the larger combined image is arranged. The associated revealing pattern then includes of a first revealing pattern matched to the larger combined image, and of a second revealing pattern matched to the smaller combined image.

(76) The two different combined images may have similarities and/or complement each other. They may in particular be identical and/or symmetric.

(77) A coating that is visible under preset illumination conditions, such as a luminescent coating, a fluorescent coating, for example, may be deposited on the metal elements and/or the lacquer. For example, FIG. 12 shows a print 60 of a UV ink describing an AWS pattern that is observable only when under UV illuminant.

(78) The security structure according to the various exemplary embodiments described herein may be incorporated into a security document, such as a banknote, or into other security documents such as a card, such as a multilayer card, a page containing personal data, or a film for protecting personal data.

(79) The carrier is, for example, a thread or a foil or a sticker. The carrier may be a transparent film that may, for example, extend over the entire length and width of the document.

(80) The expression comprising a must be understood as being synonymous with comprising at least one, unless otherwise specified.