EP3397502B1 - Secure article comprising a combined image and/or a revelation screen - Google Patents

Description

The present invention relates to the field of secure articles.

Background

In order to guard against counterfeiting or falsification and in order to increase the level of security, it is known to use security elements applied on the surface or introduced en masse or in window (s) in a secure article, for example a label, packaging, especially for drugs, food, cosmetics, electronic parts or spare parts.

The secure article can in particular be chosen from a means of payment, such as a bank note, a bank card, a check or a restaurant ticket, an identity document such as an identity card, a visa, a passport or driving license, a secure card, a lottery ticket, a transport ticket or an entrance ticket to events.

It is known from patent applications EP 2 367 695 , EP 2,585,308 and EP 2,586,014 and patent EP 2 454 102 masking effects of images imbricated by a revelation screen allowing, when the revelation screen and the image are superimposed, the observation of an image by displacement of the revelation screen relative to the image or by change of the viewing angle.

WO 2011/007344 A1 (this document and EP 2 454 102 take advantage of a common priority) describes a secure article comprising a revelation frame and a combined image, the combined image being composed of a plurality of nested images, the combined image comprising periodic alternation in a first direction, of nested image elements, the elements belonging to different nested images being of different colors, the revelation frame comprising a periodic alternation in a second direction of a blackout frame element with a non-blackout frame element, the dimension according to the second direction of the non-occulting frame elements being greater than the dimension according to the first direction, of at least one element of nested images, the revealing frame allowing, when it is superimposed on the combined image, to observe different revealed images by changing the viewing angle. WO 2011/007344 A1 also describes on the one hand that the elements belonging to the same nested image are of the same color and the elements belonging to different nested images are of different colors, on the other hand that the dimension in the second direction of the non-occluding frame elements is greater than the dimension in the first direction, of at least one element of nested images, but does not describe these two characteristics in combination.

However, these patents are generally limited to viewing a single nested image at a time.

It is also known from the patent application EP 2,740,607 a system comprising a revelation screen, a layer exhibiting pigments which can be oriented by a external magnetic field and a magnetic layer having a grid of north and south poles, the revealing grid and the grid of north and south poles being of different colors. WO 2014 096 794 describes a first screen on which a second surface screen is embossed, the screen lines of the first screen exhibiting the same color in visible light and different colors when viewed under a combination of visible and invisible lights and the two screens being such that the device exhibits a different color, depending on the viewing angle, when exposed to a combination of visible and invisible lights.

Abstract

There is a need to benefit from secure articles comprising an anti-counterfeiting optical system using the tools of players in the field of secure articles, capable of producing optical effects which can contribute to the authentication and / or identification of the article. , and whose possible incorporation into an article such as a paper can be done relatively easily.

The invention aims to meet this need and has for object, according to a first of its aspects, a secure article comprising a revelation frame and a combined image, or an assembly comprising a secure article and another object, according to claim 1. .

The fact of obtaining a revealed image formed of more than one nested image makes it possible to have new visual effects according to the visible nested images, and thus offers new possibilities of authentication, in particular accessible to the man in the street.

Thanks to the invention, it is thus possible to benefit from a secure article offering a new means of authentication, consisting in the formation of different revealed images, leading for example to the formation of a particular colored pattern easily recognizable by the man in the street.

The other aforementioned object is for example similar in its function and / or in its form to the secure article according to the invention. For example, the secure article and the other object are banknotes, in particular with the same fiduciary value. The secure article and the other object can then only be differentiated from one another by a serial number for example.

The revealing screen has blackout screen elements and non-blackout screen elements.

The blackout elements provide a visual contrast with the non-blackout elements. The border between a blackout element and a non-blackout element is thus determined by whether or not it is possible to observe the desired effect, by superposition with the combined image.

This observation can be done through the non-occulting elements. As a variant, the combined image is located between the revealing frame and the viewer, and the shadowing elements prevent the viewer from discerning the shadowing elements of the nested image which are superimposed on it. In examples, the non-occulting element is perfectly transparent or of a sufficiently low uniform opacity or else of a sufficiently light shade to make it possible to observe through it or on it the element or elements of nested images leading to the desired effect. In this case, the dimension along one direction of the non-occulting element corresponds to the width along this direction of the perfectly transparent zone or of sufficiently low uniform opacity or of sufficiently light shade. In these examples, the transition between a blackout element and a non-blackout element is straightforward. In other examples, the blackout element and / or the non-blackout element form (s) a gradient. In this case the limit of the non-blackout element in one direction, useful for determining its dimension in this direction, is that from which the opacity is sufficiently strong or the shade sufficiently dark to prevent seeing the desired effect. through or on the element. For example, in the case where the transition between a blackout element and a non-blackout element is done with a continuous gradient of opacity gray varying in one direction between Op _min and Op _max , and beyond a opacity Op _occ it is no longer possible to see the desired effect through the element, the dimension of the non-occulting element is given by the dimension according to this direction of the zone of the element where the opacity is less than or equal to Op _occ .

Preferably, the revealing frame comprises a finite number of frame elements. More preferably, the raster elements do not exhibit any gradient.

More preferably, the non-blackout elements are each opacity or luminosity (L * in the (L *, a *, b *) CIE94 system) uniform, which can be zero, respectively weak, and the blackout elements are also preferably opacity or uniform brightness.

Combined image

The combined image can comprise a periodic alternation of elements of nested images in several first directions, in particular two first directions perpendicular to each other, as detailed below.

The combined image can include at least two nested images, preferably at least three.

The combined image can include at least two elements of each nested image, preferably at least three.

Depending on the or each of the directions, the successive elements of the same nested image can be spaced apart by a distance defining a period.

The or each period may be between 10 μm and 1 mm, preferably between 50 μm and 200 μm.

According to the invention, the nested image elements belonging to different nested images are of different colors. According to the invention, there is a colorimetric difference ΔE * 94 according to the C.I.E. 1994 greater than or equal to 2, preferably greater than or equal to 3. This makes it possible to have a polychrome combined image.

As is commonly accepted and specified in the C.I.E. 1994, the color is defined by the combination of three parameters which are the hue, the saturation and the luminosity. Hue is the perception of color measured on a color disk, saturation is the purity of the color, and lightness is the degree of lightening or darkening of a color.

Preferably, the nested image elements belonging to different nested images are of different hues.

The elements belonging to different nested images, in particular to at least two of the different nested images, can be different in their appearances, in particular their hues, opacities, saturations, luminescences or shine, and / or present a contrast, in particular a saturation contrast , intensity, hue and / or luminance, and / or a sufficient colorimetric difference to make it possible to distinguish, in particular under white light, two adjacent nested image elements when viewed at some magnification. So at least two of the, better all nested images, look different.

The nested image elements of the same nested image are, according to the invention, of the same color but of a different color from those of the other nested images. During the superposition of the revealing frame with the combined image, under given observation conditions, the revealed image can then be an image whose color is defined by the proportion of each visible nested image, that is ie the proportion of each color. For each image revealed, the proportion of a nested image is between 0 and 1, the value 0 being assigned to a nested image when the latter is not a component of the revealed image, that is to say when the latter is completely obscured by the revelation frame and the value 1 being assigned when the entire nested image is a component of the revealed image, that is to say when the latter is not all obscured by the web of revelation. The revealed images are of different colors. For example, the combined image comprises three nested images of respective colors red, green and blue and the revealed image is of a color dependent on its proportion in each of the nested images, the color being easily determined by its RGB coordinates. The RGB coordinates are in the form of three numbers between 0 and 255 characterizing said color, each number representing the proportion of one of the red, green and blue components making it possible to obtain said color.

The term “under given observation conditions” is understood to mean a given position and a given orientation of the revealing frame with respect to the combined image and a given viewing angle of the revealing frame and of the combined image.

The colors of the nested image elements may or may not be primary colors.

Preferably, the combined image, and the nested images that it comprises, are raster images; the combined image may be a colored frame.

The nested image elements can be fluorescent and have different appearances, in particular colors, under UV light. This makes it possible to have revealed images observable under UV light, different or not from the revealed images observable in visible light.

When nested image elements are luminescent, they may or may not be visible in white light.

The nested image elements are preferably all of the same size in the or each of the directions.

The dimension of the elements of nested images according to the or each of the directions is, preferably, equal to the period according to this direction divided by the number of nested images. This dimension may be less than or equal to 1 mm, better still less than or equal to 100 μm, still better less than or equal to 50 μm. Thus, the nested image elements are contiguous. Each nested picture element can be partially superimposed with one of the adjacent elements, the superposition width being less than or equal to 10%, better still 5% of the dimension of the nested picture element in said direction.

As a variant, at least two elements of nested images can be of different dimensions according to the or one of the directions.

The nested image elements preferably have the same general shape.

For example, the combined image comprises a periodic alternation of lines of nested images, of longitudinal axes parallel to each other in one direction. The alternation between the lines of nested images takes place in a direction, for example perpendicular to the longitudinal axes of the lines of nested images. The longitudinal axes of the nested image lines define a general orientation of the combined image.

Each nested image can be formed of continuous or broken lines, preferably continuous, two successive lines of the same nested image being spaced from each other by a distance S defined between the longitudinal axes of the two adjacent lines, the latter defining the period of l 'combined image. The lines of the same nested image may or may not all be identical.

The lines of a nested image are preferably all the same length. But it can be otherwise, and at least two lines of nested images can be of different lengths.

Each line of a nested image is preferably of constant width l over its entire length, its longitudinal edges being mutually parallel.

The lines of nested images are preferably all of the same width.

The width l of the nested image lines is preferably equal to the period divided by the number of nested images. Thus, the nested image lines are contiguous. The width l of the nested image lines may be less than or equal to 1 mm, better still less than or equal to 100 μm, even better still less than or equal to 50 μm.

Each line of nested images can be partially superimposed with one of the adjacent lines, the width of the superposition being less than or equal to 10%, better still 5% of the width of said line of nested images.

Alternatively, at least two lines of nested images are of different widths.

The lines of nested images preferably have the same general shape, in other words, the edges of the lines of nested images are parallel to each other. The lines of nested images may or may not be rectilinear, for example curved, wavy or crenellated.

The combined image may have a resolution greater than or equal to 800dpi. In other words, for its realization, it requires printing or manufacturing means other capable of producing details corresponding to such a resolution.

The combined image can be as such, that is to say by being observed directly without passing through the revelation screen, of homogeneous appearance to the naked eye at a normal observation distance taking into account its finesse. In particular, the combined image may appear to the naked eye at a normal viewing distance to have a uniform appearance, especially color. This allows, if desired, to have revealed images which present a homogeneous appearance to the naked eye at a normal viewing distance.

By “normal viewing distance” is meant the usual viewing distance of a secure article, for example 30 cm and preferably 15 cm.

In the case of nested images of different colors, the combined image and the revealing screen are according to the invention arranged such that the revealed images each appear of a solid color.

The combined image can have any suitable contour, and in particular its contour can define a pattern which is also found on the article; the combined image is for example an outline defining a pattern such as a character, animal, plant, monument or alphanumeric sign, which also appears on the article, for example in the form of a print or a watermark.

Screening of revelation

The revelation frame may comprise a periodic alternation of a blackout frame element with a non-blackout frame element in several second directions otherwise called orientations, in particular two directions perpendicular to each other.

The blackout raster element and the non-blackout raster element are preferably of different opacities, transparencies and / or hues, in particular one raster element is opaque and the other element is at least partially transparent . For example, the revelation frame is formed of a periodic alternation of occulting elements, for example substantially opaque black and non-occulting elements, for example transparent, otherwise called interlines. Therefore, when the revealing screen and the combined image are superimposed, the blackout elements prevent the observation of part of the combined image and the non-blackout elements allow the remainder of the combined image to appear.

Alternatively, the blackout raster element is a filter which is such that when superimposed on the combined image, the combined image portions on which it is superimposed are not visible. For example, the revealing screen is a color filter which does not allow any of the colors of the combined image to pass.

Preferably, the frame elements have the same shape as the nested image elements. That is, if the nested picture elements are in the form of lines, the raster elements are in the form of lines as well.

Advantageously, when the revealing frame and the combined image are superimposed, the frame and the combined image have the same or the same orientations, that is to say that the first direction (s) are aligned with the second (s). respective directions. Therefore, when the revealing frame and the combined image are superimposed, the frame elements are superimposed on the nested image elements of the combined image; the obscuring raster elements hide part of the nested image elements of the combined image, and the non-hidden nested image elements form the revealed images.

For the same dimension in a direction of the nested image elements, a revelation frame having small-dimension occulting raster elements allows the observation of a revealed image comprising a greater proportion of nested images, in particular of colors, than a revealed image observed with a revealing screen having larger-dimension occulting screen elements.

According to the invention, the period of the revelation frame according to the or one of the second directions is substantially equal to the period of the combined image according to the or one of the first directions.

The revelation frame or each block can include at least 5 blackout frame elements according to the or each of its directions.

For example, the revelation frame comprises a periodic alternation of an occulting frame line with a non-occulting frame line of longitudinal axes parallel to one another.

Preferably, the two frame lines have parallel longitudinal axes and define a general orientation of the revealing frame.

Preferably, each weft line is of constant width over its entire length, its opposite longitudinal edges being mutually parallel. The blackout raster lines and the non-blackout raster lines which alternate between them may or may not be of the same width.

Preferably, the two frame lines have the same general shape, in particular the same general shape as the nested image lines.

The two screen lines are preferably rectilinear, but in a variant the revealing screen comprises screen lines which are not rectilinear, for example being curved, wavy or in crenellations.

Preferably, the edges of one of the frame lines are parallel to the edges of the other of the frame lines.

The resolution of the revealing screen is preferably greater than or equal to 800 dpi.

The revelation screen may as such have a homogeneous appearance to the naked eye at a normal viewing distance, taking into account its fineness. In particular, the frame of visualization may appear observed with the naked eye at a normal viewing distance and in white light as having a uniform appearance, especially color.

The revealing screen can have an outline of any shape, for example circular, oval, in disc section, star, polygonal, for example rectangular, square, triangular, hexagonal, pentagonal or diamond, or form a more complex pattern, in particular a motif representing a text, an alphanumeric sign, an ideogram, an object, a person, a plant, a monument and / or an animal.

The disclosure frame may include an inclusion of another security means, in particular of another disclosure frame.

The revealed images are observable in reflected light and / or in transmitted light, and preferably they are observable in both reflected light and in transmitted light.

According to the invention, the images revealed have a homogeneous appearance to the naked eye at a normal viewing distance, according to the invention a homogeneous color. In the case according to the invention of nested images of different colors, the revealed image obtained is homogeneous and has a color resulting from the combination of the colors of the nested images composing it according to their visible proportions and the appearance of the elements. blackout weft.

The revealed images are preferably observable from both the reveal screen side and the combined image side.

Preferably, the images revealed have different appearances, in particular different colors (according to the invention) and / or different brightnesses.

At least one revealed image can consist of at least two adjacent nested images.

Alternatively, at least one revealed image can include a single nested image.

Preferably, the revealed image forms a macromotif when the revealing frame is superimposed on the combined image, under given observation conditions. Preferably, this macromotif is visible when the orientation of the revelation frame is the same as that of the combined image.

Preferably, the images revealed form macromotifs having different appearances, in particular different colors and / or shine, for example different RGB coordinates and / or different patterns, for example different stages of a movement.

The macromotif may change appearance during a displacement according to the or one of the directions of the combined image, and / or a change in the angle of observation. For example, in the case of a combined image formed of nested images of different colors, the pattern may change color.

The macromotif may disappear during a change in the orientation of the revealing screen relative to that of the combined image, in particular when the orientation of the revealing screen becomes different from that of the combined image.

The macromotective formed can be of any shape, in particular represent a text, an alphanumeric sign, an ideogram, a geometric shape, an object, a person and / or an animal.

The secure article or assembly may include a second disclosure frame separate from the first disclosure frame and intended to be superimposed on the same combined image.

As a variant, the combined image can be formed from a periodic alternation of pixels of nested images in two first non-parallel directions, in particular separated by an angle of 60 ° or 90 °, preferably perpendicular.

The term “pixels” is understood to mean an elementary pattern. A pixel can be polygonal in shape, including triangle, hexagon, rectangle or square.

The revelation frame can be formed by periodically alternating a blocking frame pixel with a non-occulting frame pixel in two second directions. Preferably, when the revealing frame and the combined image are superimposed, the first directions are aligned with the second directions. Thus, the occulting raster pixels prevent the observation of a part of the pixels of nested images allowing only a certain proportion of each nested image to appear for each revealed image.

Alternatively, when the combined image or each combined image block is formed from a periodic alternation of nested image pixels in two non-parallel directions, the associated revealing frame or each associated frame block can be simplified (e ) by defining a periodic alternation of blackout raster elements and non-blackout raster elements in the form of lines.

Observation

The combined image and / or the revelation screen can be carried on the secure article or the other object by a printing process, in particular offset, intaglio, laser, gravure, letterpress or screen printing, the combined image and / or the revelation screen being printed with colored inks or not, visible to the naked eye, under ultraviolet (UV) and / or infrared (IR) light, opaque, fluorescent, translucent and / or transparent. According to the invention, the combined image must be printed with colored inks.

The combined image can be printed in particular by a combination of colors having sufficient respective colorimetric differences, for example printing in CMYK (Cyan, Magenta, Yellow, Black) and preferably in RGB (Red, Green, Blue).

Advantageously, metallizations and / or demetallizations are used in order to avoid counterfeiting by printing.

Thus, the combined image and / or the revealing screen can include metallizations and / or demetallizations, for example in different metals, in particular in copper or in aluminum and their alloys.

The combined image and / or the reveal screen may still be printed with liquid crystals and be worn on an area of the secure article polarizing light, such that the combined image and / or the reveal screen does not. are visible only when folding the article on itself or through an external polarizer.

At least one of the combined image and the revealing screen may appear on an area of the secure article which is at least partially transparent, the superposition of the revealing screen and the combined image being effected by folding the secure article or by superimposing the secure article with the other object. The revealing frame can allow, when superimposed at least partially on the combined image of the secure article or of the other object, to observe different revealed images by a relative displacement of the revealing frame with respect to the combined image according to the or one of the directions of the combined image and of the revealing frame, and / or by a change of observation angle of the combined image and of the revealing frame. For example, in the case where the combined image is formed from nested images of different colors, the revealing raster may allow, when superimposed on the combined image so that they have the same orientation, the observation of a certain color and said color may change during a change in the viewing angle and / or when the revelation screen is moved in the direction or one of the directions of the combined image and the revelation screen, in particular perpendicular to the longitudinal axes of the image lines. frame of the block and lines of nested images.

Folding of the secure article may take place along a center line of the article, preferably parallel to one side of the article, for example along a center line passing through the middle of the length of the article.

The revealing screen and the combined image can be superimposed by being separated from each other by an interval of constant thickness. This gap can be formed by a transparent or translucent substrate having on the side of a first face of the substrate the combined image and on the side of a second face of the substrate, opposite the first, the revealing screen superimposed on the image. combined. The revelation frame can then make it possible to observe different revealed images, by a parallax effect, during a change in the direction of observation of the secure article. The interval between the revealing frame and the combined image is preferably greater than or equal to the period of the revealing frame, in particular between 10 μm and 1 mm, being for example less than 25 μm.

In this case, the revelation frame can make it possible to observe different revealed images during a change in the direction of observation of the secure article.

The substrate may comprise or be constituted by a thermoplastic material, for example a polyolefin, for example polyethylene (PE), polyvinyl chloride (PVC), polyester, polyethylene terephthalate (PET), polycarbonate (PC), polyester carbonate (PEC), polyethylene terephthalate glycol (PETG), acrylonitrile butadiene styrene (ABS) or a light-collecting film, for example of the “waveguide” type, for example a luminescent film based on polycarbonate sold by the company BAYER under the name LYSA®.

The substrate can comprise cellulosic fibers and in particular paper. In particular, the substrate can be a sufficiently translucent paper to allow the nested images to be revealed, in particular a tracing paper.

The substrate can also be transparentized locally or not, by watermarking as described in the patent. EP 1252389 or by application of a generally fatty composition which makes it transparent permanently, for example a composition made of oil and transparent mineral material, as described in the patent US 2,021,141 , or for example a composition in the form of a wax combined with a solvent.

The substrate can also be transparentized by locally applying a wax by hot transfer, as described in the patent. US 5,118,526 .

It is also possible to use for the substrate a fibrous layer comprising a hot-melt material, for example polyethylene, as described in the patent. EP 0 203 499 , which under the local action of heat will see its transparency vary.

Secured article

The secure article may be at least partially made of paper or plastic, in particular comprising a laminated or extruded plastic sheet.

The secure article may include at least one paper jet, in particular based on natural and / or synthetic fibers, for example cotton or linen fibers in the case of a bank note.

The secure article can be at least partially transparent, opaque or translucent, in particular opaque in reflected light and translucent in transmitted light.

The combined image and / or the revelation screen can be carried by a film, a lamination strip, a patch and / or a foil appearing on the secure article. The film, the lamination strip, the patch and / or the foil may include metallizations and / or demetallizations, for example made of aluminum or copper, or all types of prints.

The term “patch” is understood to mean an element of smaller dimensions than that of the secure article and which may not extend to the edge of the article. The patch may have a polygonal, circular or oval outline or forming a more complex pattern, in particular a pattern representing a text, an alphanumeric sign, an ideogram, an object, a person, a plant, a monument and / or an animal.

The term “foil” or “lamination strip” is understood to mean an element applied in particular hot, for example by transfer to the secure article, in particular from a supporting structure.

The film, the lamination strip, the patch and / or the foil can include holographic prints and / or liquid crystals.

The combined image and / or the revelation screen can also be carried by a security thread, incorporated on the surface, in bulk or preferably in window (s) in the secure article.

The combined image and / or the revelation screen can be incorporated as a window in the secure article.

The window may be formed on the secure article during its manufacture.

The window can be formed by a lack of material, for example the local absence of paper, above or below the combined image and / or the revealing screen, the window being preferably at least partially transparent or translucent on the side of the combined image and / or the revelation screen opposite to the lack of material.

The window may still not have any lack of material. The window can for example be at least partially transparent or translucent above or below the combined image and / or the revealing screen, the transparent or translucent zones being superimposed on one another so as to be able to observe the two opposite sides of the secure article.

The window can still be through. The window may have gaps in material superimposed on either side of the secure article. The two sides of the secure article can thus be directly observable and not through transparent or translucent zones. The revealing screen and / or the combined image can be incorporated completely in the window or partially.

The article may also have a plurality of windows as described above. The windows may or may not all be of the same type. Examples of the production of windows in secure articles are, for example, given in GB 1,552,853 which discloses the creation of a window in particular by transparentization, laser cutting, abrasion or mechanical incision, EP 0 229 645 which describes the creation using masks of a window on one side or on both sides of a bijet paper, WO 2004/096482 which describes the creation of a window by laser cutting, CA 2 471 379 which describes the creation of a transparent window and association with a security element and WO 2008/006983 which describes the creation of a transparent window on a bijet paper.

The secure article may also include a security thread presenting the combined image and / or the disclosure frame, in particular a succession of combined images and / or disclosure frames.

The secure article may also include two security threads, one carrying at least one combined image and the other carrying at least one corresponding revelation frame. The security thread (s) may be of sufficient width to enable the combined image and / or the revealing screen to appear therein in its entirety. The width of the security thread (s) is preferably between 3 and 20 mm, more preferably between 4 and 10 mm and for example equal to 6 mm.

As indicated above, the revealing screen and / or the combined image advantageously appear on an area of the article which is at least partially transparent, in particular the revealing screen and / or the combined image can be at least partially transparent.

The at least partially transparent zone may correspond to a recess, passing through or not, of the article in which the revealing screen and / or the combined image are placed.

The zone is for example constituted by a translucent tracing paper.

The zone may also consist of a polymer layer comprising, for example, polyethylene (PE), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polycarbonate (PC), polyester carbonate (PEC), polyethylene terephthalate. glycol (PETG), acrylonitrile butadiene styrene (ABS) or a light collecting film, for example of the “waveguide” type, for example a polycarbonate-based luminescent film sold by the company BAYER under the name LYSA® .

The secure article, as well as the elements that it comprises such as for example a security thread, a patch and / or a foil, may include one or more additional security elements as defined below.

Among these additional security elements, some are detectable by eye, in daylight or in artificial light, without using a particular device. These security elements include, for example, colored fibers or planchettes, totally or partially printed or metallized threads. These security elements are said to be first level.

Other types of security elements are detectable only with a relatively simple device, such as a lamp emitting in the ultraviolet (UV) or infrared (IR). These security elements include, for example, fibers, boards, bands, threads or particles. These security features may be visible to the eye naked or not, being for example luminescent under lighting from a Wood lamp emitting at a wavelength of 365 nm. These security elements are said to be second level.

Still other types of security elements require a more sophisticated detection device for their detection. These security elements are for example capable of generating a specific signal when they are subjected, simultaneously or not, to one or more external excitation sources. The automatic detection of the signal makes it possible to authenticate, if necessary, the article. These security elements include, for example, tracers in the form of active materials, particles or fibers, capable of generating a specific signal when these tracers are subjected to optronic, electrical, magnetic or electromagnetic excitation. These security elements are said to be third level.

The additional security elements present within the secure article may have first, second or third level security characteristics.

The secure item can be a means of payment, such as a bank note, check, bank card or restaurant ticket, an identity document such as an identity card or visa or passport or a driving license, a lottery ticket, a secure card, a transport ticket or an entrance ticket to cultural or sporting events.

Imager

As a variant, the other object is an electronic imager making it possible to form a first image, the first image being the revealing frame or the combined image, in order to be able to superimpose it on a second image present on the secure article, the second image being the other of the revelation frame and the combined image.

The term “electronic imager” is understood to mean an electronic device making it possible to produce an image by display or projection.

The electronic imager may include a screen on which the first image is displayed.

The electronic imager can include a screen of any known type, for example a computer, television, mobile phone, book or diary screen. electronic, a personal digital assistant ("Personal Digital Assistant"), a digital tablet, a watch face, this list being non-exhaustive.

The electronic imager can be a projector, without or without a screen onto which the projection is carried out. The projector can make it possible to project the first image on a background or on the security article.

The electronic imager can be a projector of any known type, for example a slide projector, a video projector, an overhead projector, a picoprojector or nanoprojector, for example a miniaturized video projector integrated into a portable device (PDA, cell phone, laptop computer, etc. for example), a cinematographic projector, this list being non-limiting.

The electronic imager preferably makes it possible to generate a pixelated image, each pixel of which is individually addressable, preferably with at least 256 levels of gray or colors, and / or with a resolution of between 50 and 1000 dpi ("Dot Per Inch" or “Points Per Inch”).

The electronic imager can be a projector projecting visible, infrared (IR) and / or ultra-violet (UV) light.

The electronic imager may include a screen of the LCD (“Liquid Crystal Display”), LED “Light Emitting Diode”), OLED (“Organic Light Emitting Diode”), laser, plasma, electrochromic, FED (“Field Emission Display”) type. ), SED (“Surface-conduction Electron-emitter Display”), LCOS (“Liquid Crystal On Silicon”) or even a cathode ray tube.

The electronic imager preferably includes a liquid crystal display (LCD).

The screen may have a resolution of between 50 and 600 dpi, better still between 100 and 300 dpi, for example equal to 160 dpi.

The second image may appear on an area of reduced opacity of the secure article. Such a zone of reduced opacity may in particular correspond to a zone of lesser thickness, to a zone made transparent or to a zone comprising at least one layer of a material of lower opacity. The opacity of said zone of reduced opacity will in particular be sufficiently low to allow observation in transmission of the first image. Preferably, the second image is visible in transmission and in reflection.

The second image can appear on an at least partially transparent or translucent zone of the secure article.

When the electronic imager produces the first image by means of polarized light, the second image preferably appears on an area at least partially transparent or translucent, in particular an at least partially transparent window.

The first image produced by the electronic imager can be displayed on the electronic imager, for example on a screen of the electronic imager.

As a variant, the first image is projected by the electronic imager, for example on a background or on the secure article. In particular, when the first image is projected on a background, the second image of the secure article can be superimposed on the first image projected on the background. As a variant, the first image is projected at least partially on the second image of the secure article.

The article and the imager may or may not come into contact when the images are superimposed.

The first image and / or the second image may exhibit polarization properties.

For example, the first image is produced by the electronic imager by means of polarized light, in particular rectilinearly, circularly or elliptically polarized light. The electronic imager may include a screen emitting polarized light or projecting polarized light.

The secure article may include a polarizing filter. In particular, the second image can be produced using a polarizing filter.

• réalisation d'une ou plusieurs perforations dans au moins un filtre polarisant pour former la deuxième image,
• chauffage local d'au moins un filtre polarisant, par exemple à l'aide d'un laser, de façon à supprimer localement les propriétés polarisantes du filtre et à former la deuxième image,
• application sélective, par exemple par impression et/ou collage, sur au moins un filtre polarisant, d'un matériau diffusant, par exemple une silice colloïdale et/ou une bande adhésive, pour former la deuxième image,
• réalisation d'au moins une attaque sélective par réaction chimique et/ou par émission de rayonnement lumineux, notamment ultra-violet (UV) et/ou infrarouge (IR) et/ou laser, sur au moins un filtre polarisant, éventuellement à l'aide d'un masque, pour former la deuxième image, de façon notamment à annuler localement l'effet polarisant du filtre,
• application, notamment par impression ou par couchage, d'au moins un effet polarisant, notamment d'un composé polarisant, par exemple à l'aide d'une encre comportant ledit composé polarisant, sur un substrat donné non polarisant, notamment un film polymère, pour former la deuxième image,
• application, notamment par impression ou par couchage, d'au moins une composition comportant des cristaux liquides, notamment cholestériques, par exemple telle que celle commercialisée par la société SICPA sous la dénomination Oasis®, sur un substrat donné polarisant, notamment un film polymère, pour former la deuxième image.

The second image can be produced according to at least one of the following steps:

• making one or more perforations in at least one polarizing filter to form the second image,
• local heating of at least one polarizing filter, for example using a laser, so as to locally remove the polarizing properties of the filter and to form the second image,
• selective application, for example by printing and / or gluing, on at least one polarizing filter, of a diffusing material, for example a colloidal silica and / or an adhesive tape, to form the second image,
• carrying out at least one selective attack by chemical reaction and / or by emission of light radiation, in particular ultra-violet (UV) and / or infrared (IR) and / or laser, on at least one polarizing filter, optionally with the using a mask, to form the second image, in particular so as to locally cancel the polarizing effect of the filter,
• application, in particular by printing or by coating, of at least one polarizing effect, in particular of a polarizing compound, for example using an ink comprising said polarizing compound, on a given non-polarizing substrate, in particular a polymer film , to form the second image,
• application, in particular by printing or by coating, of at least one composition comprising liquid crystals, in particular cholesteric, for example such as that sold by the company SICPA under the name Oasis®, on a given polarizing substrate, in particular a polymer film, to form the second image.

By way of remark, depending on the desired effect, the steps stated above will be carried out so as to form an image which is the positive or negative image of the second image. In particular, it is possible to apply locally to at least one polarizing filter, for example by printing, a polyether-based aliphatic polyurethane, for example such as that sold by the company LAMBERTI under the name Esacote® PU 21 / S.

In the last possibility mentioned above, when during the implementation of the method according to the invention, the composition comprising cholesteric liquid crystals is situated between the polarizing substrate and the electronic imager, the cholesteric liquid crystals modify the polarized light. of the electronic imager which is not stopped by the substrate and the areas covered with cholesteric liquid crystals appear transparent when the polarizing substrate is oriented so as to be opaque.

On the other hand, when the polarizing substrate is located between the composition comprising cholesteric liquid crystals and the electronic imager, the cholesteric liquid crystals exhibit an optically variable effect when the polarizing substrate is oriented so as to be opaque. The optically variable effect of crystals Cholesteric liquids is more generally known under the name of “colorshift” effect, the color of the cholesteric liquid crystals depending on the angle of observation and the latter being observed in particular against a dark background, preferably black in color. The “colorshift” effect of cholesteric liquid crystals can constitute an additional security for authenticating and / or identifying the secure article.

Thus, in particularly preferred implementation examples of the method according to the invention, the second image is defined by a first polarizing material superimposed on a second polarizing material, the first material extending in particular in patterns corresponding to the second image. and the second material extending continuously. The first material is preferably a cholesteric liquid crystal print and the second material is preferably a linearly polarizing substrate.

By “patterns corresponding to the second image” is meant that said patterns form the second image in negative or positive.

Advantageously, when the first and second images exhibit polarization properties, there is only one orientation of one with respect to the other allowing one to partially mask the other. In other words, there is only one orientation of the first image relative to the second image making it possible not to be able to observe the first image through the polarizing zones of the second image, or vice versa. Indeed, the first and second images exhibiting polarization properties consist of polarizing zones and non-polarizing zones. When placed in front of a light source emitting polarized light, there is only one orientation in which the polarizing areas become opaque.

In particular, in the case where the article comprises a polarizing filter there is for example only one orientation of the second image relative to the first image projected or displayed by the electronic imager by means of polarized light , which allows the polarizing filter to mask the polarized light of the electronic imager. The polarizing filter may appear opaque, in particular black in color, only in this orientation, which is preferably single, of the first image relative to the second image.

The presence of a single orientation of the first and second images relative to each other as described above can make it possible to authenticate and / or identify the secure article according to a first level of security.

The electronic imager, for example the screen of the electronic imager, and / or the secure article may include an indicator making it possible to inform the user on how to position the first and second images with respect to one another. 'other to obtain said orientation, for example a visual cue.

According to an alternative embodiment, the second image is printed with a compound, in particular liquid crystals, visible only when placed in front of an electronic imager emitting polarized light, in particular a liquid crystal screen. Advantageously, the second image is transparent under unpolarized illumination, for example under natural lighting, and is visible only under polarized illumination using the electronic imager, which provides additional security for the secure article.

The secure article may include an integrated microcircuit, for example an RFID chip or an optical chip (activated for example by the light coming from the electronic imager), capable of communicating with the electronic imager so that the latter produces, in particular displays and / or projects information providing information on how to position the first and second images with respect to one another to obtain said orientation.

The secure article may include an integrated microcircuit, for example an RFID chip or an optical chip, capable of communicating with the electronic imager so that the latter produces at least one first image, the association of which with the second image makes it possible to put implementing the method according to the invention. In particular, the electronic imager can produce at least a first image associated with a second image of the secure article by communication between the electronic imager and the integrated microcircuit.

The electronic imager can also produce at least a first image from a photo and / or a video of the secure article, in particular from the second image of the secure article or from an identifier present on the. item, for example a logo or serial number. The photo and / or video can be produced with the electronic imager, an image capture device, for example a digital camera, connected to the electronic imager by a wired link or not and / or be transferred to the imager. electronic, for example from a data storage device or via a network, such as the Internet.

The first image can be produced only from the photo and / or video of the secure article, or alternatively, be produced from the photo and / or video of the secure article and additional information, for example example information present on the secure article, on the photo and / or video, entered by the user, or even received from a network, for example from a secure server.

The electronic imager may include a program making it possible to identify the secure article, and in particular the second image, and to produce, in particular to display and / or project, a first image obtained from a database providing information. on the first image to be used according to the secure article, in particular the second image.

The electronic imager can produce several first images and / or the secure article can include several second images, at least one of the first images making it possible to observe the authentication and / or identification information when superimposed on the least one of the second images according to the method of the invention, or vice versa.

In particular, it may thus be possible to authenticate and / or identify the security article with different types of electronic imagers.

As a variant, a given electronic imager can make it possible to authenticate and / or identify secure articles of different types, notably comprising different second images.

For example, the second images are differentiated by their size, their color, their shape, or even by the spacing between the frame elements or nested images or the width of the latter.

The first images can also be differentiated by their size, their color, their shape, or even by the spacing between the elements of the frame or nested images or the width of the latter, or even by the size of the pixels, the spacing between pixels or pixel color.

Electronic imagers can, for example, be differentiated by their brand, their model, their resolution, their type, namely computer, television or telephone screen, or projector, for example.

The presence of several first images and / or second images can make it possible to authenticate and / or identify the security article independently of the differences mentioned above.

The first image produced by the electronic imager can come from a communication network with which the electronic imager communicates, for example a telephone network, the Internet or an internal network, the image being for example downloaded, and / or be supplied with the electronic imager, for example on a data medium, for example a hard disk, a USB stick, a CD and / or a DVD. The security article may, where appropriate, include such a data medium. The data medium can be an integrated microcircuit, for example an RFID or optical chip, communicating with the electronic imager.

The secure article can include a luminescent zone, for example fluorescent and / or phosphorescent, and the electronic imager can project the first image on the secure article under ultraviolet (UV) lighting.

In particular, the second image may be a luminescent printing, for example produced on a black opaque background of the secure article, onto which the first image is projected under UV lighting. The second image is then visible only under UV lighting.

The second image can still be printed on a luminescent background of the secure article, so that it is visible under both UV light and normal light.

Process

The subject of the invention is also a method for authenticating, according to claim 14, a secure article according to the first aspect of the invention, in which the image (s) revealed by the revelation frame is observed, the image is changed. 'viewing angle and / or position of the revealing frame relative to the combined image to observe a change in the revealed image and one concludes as to the authenticity of the article at least on the basis of this observation.

The method may include the step of aligning the first direction (s) with the respective second direction (s) when the revealing frame and the combined image are superimposed.

In the case where the combined image and the revealing screen (s) are not superimposed, the revealing screen can be at least partially superimposed on the combined image to observe the images by folding the secure article and / or by superimposing the secure article and the other object, the angle of observation and / or the position of the revelation frame with respect to the combined image is then changed to observe a change in the revealed image and one concludes as to the authenticity of the article at least on the basis of this observation.

• superposer au moins partiellement la deuxième image de l'article avec une première image formée par l'imageur électronique afin de permettre d'observer une information d'authentification et/ou d'identification de l'article sécurisé.
• superposer au moins partiellement la deuxième image de l'article avec une première image produite par l'imageur électronique suite à une communication entre le microcircuit intégré et l'imageur électronique,
• superposer au moins partiellement la deuxième image de l'article avec une première image produite par l'imageur électronique à partir d'une photo et/ou vidéo de l'article sécurisé, notamment de la première image,

When one of the revelation frame and the combined image is formed by an electronic imager, the method may include at least one of the following steps:

• superimposing at least partially the second image of the article with a first image formed by the electronic imager in order to make it possible to observe an authentication and / or identification information of the secure article.
• at least partially superimpose the second image of the article with a first image produced by the electronic imager following communication between the integrated microcircuit and the electronic imager,
• superimpose at least partially the second image of the article with a first image produced by the electronic imager from a photo and / or video of the secure article, in particular of the first image,

The photo and / or video can be produced with the electronic imager, an image capture device, for example a digital camera, connected to the object and / or be transferred to the electronic imager, for example from a device data storage or via a network, such as the Internet.

• la figure 1 illustre la formation d'une image combinée,
• les figures 2A à 2C représentent une succession d'images révélées telle qu'elle peut être observée quand les conditions d'observation varient,
• les figures 3A et 3B illustrent une trame de révélation,
• les figures 3C à 3E représentent une succession d'images révélées telle qu'elle peut être observée à l'aide de l'image combinée de la figure 1 et de la trame de révélation de la figure 3A, quand les conditions d'observation varient,
• la figure 3F illustre un détail de la figure 3A,
• les figures 4A et 4C représentent des variantes de jonction entre deux parties d'une trame de révélation adjacentes,
• la figure 5A illustre une variante de trame de révélation,
• les figures 5B à 5D représentent une variante de succession d'images révélées telle qu'elle peut être observée à l'aide de l'image combinée de la figure 1 et de la trame de révélation de la figure 5A quand les conditions d'observation varient,
• la figure 6A illustre une variante de trame de révélation,
• les figures 6B à 6C représentent une succession d'images révélées telle qu'elle peut être observée à l'aide de l'image combinée de la figure 1 et de la trame de révélation de la figure 6A quand les conditions d'observation varient,
• les figures 7A et 7B représentent des variantes d'images combinées,
• les figures 8A à 8H représentent des variantes de trames de révélation,
• la figure 9 illustre des images révélées telles qu'elles peuvent être observées à l'aide de l'image combinée de la figure 1 et d'une trame de révélation,
• les figures 10A et 10B illustrent des images révélées telles qu'elles peuvent être observées à l'aide de l'image combinée de la figure 1 et de variantes de trames de révélation,
• la figure 11A illustre une variante d'image combinée, et
• les figures 11B à 11D représentent une variante de succession d'images révélées telle qu'elle peut être observée à l'aide de l'image combinée de la figure 11A et d'une trame de révélation quand les conditions d'observation varient.
• la figure 12 représente en coupe, de façon schématique et partielle, un exemple d'article sécurisé réalisé conformément à un exemple de mise en œuvre de l'invention,
• la figure 13 illustre la possibilité de faire varier l'inclinaison en déformant l'article sécurisé,
• les figures 14 et 15 représentent deux exemples d'articles sécurisés selon l'invention,
• les figures 16A à 16D représentent d'autres exemples d'articles sécurisés selon l'invention, en section transversale, de façon schématique,
• les figures 17 et 18 illustrent des variantes de réalisation d'articles sécurisés selon l'invention, en section transversale, de façon schématique,
• la figure 19 représente un exemple de réalisation d'article sécurisé selon l'invention, l'image combinée ou la trame de révélation étant portée par une fenêtre de l'article,
• la figure 20 représente l'article sécurisé plié,
• les figures 21 et 22 représentent des exemples de réalisation d'article sécurisé selon l'invention, l'image combinée ou la trame de révélation étant portée par une fenêtre de l'article,
• les figures 23 à 27 représentent d'autres exemples de réalisation d'articles sécurisés selon l'invention, l'image combinée et/ou la trame de révélation étant portées par au moins un fil de sécurité ou un foil.
• la figure 28A représente un autre exemple d'image combinée,
• la figure 28B représente une variante avec deux trames de révélation,
• les figures 28C, 28D, 28F et 28G représentent une succession d'images révélées telle qu'elle peut être observée à l'aide de l'image combinée de la figure 28A et des trames de révélation de la figure 28B quand les conditions d'observation varient et que l'orientation des trames et de l'image combinée varie entre une position illustrée sur la figure 28E et une autre position,
• les figures 29 à 31 représentent des variantes d'ensemble comportant un imageur électronique et un article,
• la figure 32 représente une variante de premières images formées par un imageur électronique,
• la figure 33 représente une variante d'article comportant un microcircuit intégré,
• la figure 34 représente une variante d'ensemble, l'article comportant une deuxième image sous forme de trame de révélation et l'imageur électronique produisant une première image sous forme d'image combinée,
• la figure 35A représente un autre exemple d'image combinée,
• la figure 35B représente une variante avec une trame de révélation sous forme de pixels,
• les figures 35C à 35E représentent une succession d'images révélées telle qu'elle peut être observée à l'aide de l'image combinée de la figure 35A et de la trame de révélation de la figure 35B quand les conditions d'observation varient et/ou que la position relative des trames et de l'image combinée varie.

The invention may be better understood on reading the description which follows, of non-limiting examples of implementation thereof, and on examining the appended drawing, in which:

• the figure 1 illustrates the formation of a combined image,
• the figures 2A to 2C represent a succession of revealed images such as can be observed when the observation conditions vary,
• the figures 3A and 3B illustrate a plot of revelation,
• the figures 3C to 3E represent a succession of revealed images as can be observed using the combined image of the figure 1 and the revelation of the figure 3A , when the observation conditions vary,
• the figure 3F illustrates a detail of the figure 3A ,
• the figures 4A and 4C represent variants of junction between two parts of an adjacent revelation frame,
• the figure 5A illustrates a variant of the revelation frame,
• the figures 5B to 5D represent a variant of succession of revealed images such as can be observed using the combined image of the figure 1 and the revelation of the figure 5A when the observation conditions vary,
• the figure 6A illustrates a variant of the revelation frame,
• the figures 6B to 6C represent a succession of revealed images as can be observed using the combined image of the figure 1 and the revelation of the figure 6A when the observation conditions vary,
• the figures 7A and 7B represent variants of combined images,
• the figures 8A to 8H represent variants of revelation patterns,
• the figure 9 illustrates revealed images as they can be observed using the combined image of the figure 1 and a plot of revelation,
• the figures 10A and 10B illustrate revealed images as they can be observed using the combined image of the figure 1 and variants of revelation patterns,
• the figure 11A illustrates a combined image variant, and
• the figures 11B to 11D represent a variant of succession of revealed images such as can be observed using the combined image of the figure 11A and a revelation frame when the observation conditions vary.
• the figure 12 shows in section, schematically and partially, an example of a secure article produced in accordance with an example of implementation of the invention,
• the figure 13 illustrates the possibility of varying the inclination by deforming the secure article,
• the figures 14 and 15 represent two examples of articles secured according to the invention,
• the figures 16A to 16D show other examples of secure articles according to the invention, in cross section, schematically,
• the figures 17 and 18 illustrate alternative embodiments of secure articles according to the invention, in cross section, schematically,
• the figure 19 represents an exemplary embodiment of a secure article according to the invention, the combined image or the revelation frame being carried by a window of the article,
• the figure 20 represents the folded secure item,
• the figures 21 and 22 represent examples of embodiments of a secure article according to the invention, the combined image or the revelation frame being carried by a window of the article,
• the figures 23 to 27 show other embodiments of secure articles according to the invention, the combined image and / or the revelation frame being carried by at least one security thread or one foil.
• the figure 28A shows another example of a combined image,
• the figure 28B represents a variant with two revelation screens,
• the figures 28C, 28D, 28F and 28G represent a succession of revealed images as can be observed using the combined image of the figure 28A and frames of revelation of the figure 28B when viewing conditions vary and the orientation of the frames and the combined image varies between a position shown on the figure 28E and another position,
• the figures 29 to 31 represent assembly variants comprising an electronic imager and an article,
• the figure 32 represents a variant of first images formed by an electronic imager,
• the figure 33 represents a variant of an article comprising an integrated microcircuit,
• the figure 34 shows an overall variant, the article comprising a second image in the form of a revelation frame and the electronic imager producing a first image in the form of a combined image,
• the figure 35A shows another example of a combined image,
• the figure 35B represents a variant with a revelation frame in the form of pixels,
• the figures 35C to 35E represent a succession of revealed images as can be observed using the combined image of the figure 35A and the revelation of the figure 35B when the viewing conditions vary and / or the relative position of the fields and the combined image varies.

Combined image

We have illustrated at the figure 1 an example of forming a combined image I by adding a plurality of nested images I ₁ , I ₂ , ..., I _n . Each nested image I _i is formed of lines of nested images i _i arranged periodically in the direction X _I and of the same width l _i constant over their entire length. The nested images are of the same period S.

The lines of nested images i _i are parallel longitudinal axes defining a general orientation O _i of the image combined by their general direction. The periodicity is observed along an axis X _I perpendicular to the longitudinal axis of the nested image lines.

The lines of a nested image are continuous and of the same length, but it may be otherwise.

The combined image I corresponds to the superposition of these nested images I ₁ to I _n by shifting them relative to each other along the axis X _I so that the lines of nested images i ₁ to i _n do not overlap not between different images.

The widths l ₁ to l _n of the lines of the nested images i ₁ to i _n are such that the sum of the widths l ₁ to l _n of these lines i ₁ to i _n is less than or equal to the period S, and preferably, equal to period S: $${\displaystyle \sum _{j=1}^{\mathrm{not}}\mathit{lj}=S}$$

In the example illustrated, the lines of a nested image i ₁ to i ₃ have the same width l ₁ to l ₃ equal to S / 3.

As a variant, the lines i ₁ to i _n of the nested images can be of widths l ₁ to l _n different from each other, as shown in the figure. figure 7A .

In the example of figure 1 , the combined image I is formed of three nested images I ₁ to I ₃ . The first nested image I ₁ is formed by a red line i ₁ periodic, the second nested image I ₂ is formed by a green line i ₂ periodic and the third nested image I ₃ is formed by a blue line i ₃ periodic. The three lines of the nested images i ₁ to i ₃ are of the same width l . The lines of the nested images i ₁ to i ₃ are rectilinear. The resulting combined image I is a raster image exhibiting a periodic alternation of lines i ₁ to i ₃ of different colors.

The period S is between 10 μm and 1 mm, preferably between 50 and 200 μm.

The width l of the lines of the nested images i ₁ to i _n is less than or equal to 50 μm, being for example substantially equal to 33 μm. This value corresponds to a resolution of the combined image I of approximately 800 dpi, which represents a limit for conventional printers which generally have a maximum resolution of 600 dpi, and which constitutes a safety factor.

Furthermore, since the human eye does not perceive at an observation distance greater than or equal to 30 cm details less than approximately 100 μm, a sufficiently fine combined image appears to have a homogeneous appearance, for example substantially white here in transmitted light.

Also, whatever the color or colors used for the combined image, the print definition can be sufficiently precise for the mixture of colors to appear homogeneous.

In a variant further illustrated on figure 7B , the lines of the nested images i ₁ to i _n have micropatterns 7, and better still are formed by micropatterns 7. The micromotives 7 of the lines i _i of a nested image can be colored with a single color so that the lines i _i appear colored, or not. Preferably, the micropatterns 7 are of the width l of the lines i _i of the nested image and of a height of the same order of magnitude so that, in view of the resolution, the lines i _i appear of a uniform color. to the eye, the micropatterns 7 not being distinguishable with the naked eye at a distance of 15 cm. The user must for example use a magnifying glass to view the micropatterns 7, which reinforces the security of the article. The micropatterns 7 can be in positive writing or in negative writing.

In the example shown on figure 7B , the combined image I is formed of three nested images I ₁ , I ₂ and I ₃ as described previously, except that the nested image lines i ₁ , i ₂ and i ₃ are not lines of homogeneous color but lines of micropatterns 7 colored in positive writing. The lines i ₁ are made up of a repetition of the number "100" in red color, the lines i ₂ are made up of a repetition of the word "AWS" in green color and the lines i ₃ are made up of a repetition of the word Blue “BUTTERFLY”.

The combined image I can be formed by printing, in particular by four-color printing.

As a variant, the combined image I is formed by metallization and / or demetallization, in particular by metallization using metals of different colors for each of the nested images I ₁ to I _n . For example, the combined image I comprises two nested images I ₁ and I ₂ , one being in copper and the other in aluminum.

The nested images I ₁ to I _n can be glossy or matte. For example, nested images are at least partially differentiated by their brightness, with nested images being matte and other nested images being glossy.

As will be described later, the combined image I can also be formed by an electronic imager 100.

Screening of revelation

In the example shown on figures 2A to 2C , the revelation frame 4 is composed of a periodic alternation of period Q constant of straight and occulting frame lines 5a, in particular of opaque and black lines, and of non-occulting lines 5b, in particular of transparent lines of parallel longitudinal axes . The periodicity is observed along an axis X _T perpendicular to the longitudinal axis of the frame lines 5a and 5b.

The longitudinal axes of the frame lines 5a and 5b define a general orientation of the frame O _t by their general direction.

The blackout raster lines 5a are of a constant width m less than the period Q of the raster and the transparent raster lines 5b are of a constant width k, less than the period Q. Preferably, the width k of the lines of transparent frames 5b is greater than the width l of a nested image line.

The widths of the blackout screen lines 5a and the transparent screen lines 5b may or may not be identical.

In the example illustrated, the lines of frames 5a and 5b have rectilinear and parallel edges, but it may be otherwise. The revelation frame 4 may include other patterns such as crenellations or undulations, as illustrated respectively in figures 8A and 8B .

The resolution of the revealing screen 4 is preferably greater than or equal to 800 dpi.

The revelation screen 4 may as such have a homogeneous appearance to the naked eye at a normal viewing distance, taking into account its fineness. In particular, the revealing screen can appear to the naked eye at a distance of 15 cm as having a gray, uniform color, more or less dark depending on the width m of the blackout screen line 5a.

A combined image and a sufficiently fine revelation screen provide anti-photocopying security

The combined image I and / or the revealing screen 4 can be formed by printing, metallization, demetallization, laser marking, lithography or any other technique making it possible to fix or reveal an image.

To improve security, liquid crystal inks can be used, for example to print the combined image I. The animation, in order to be revealed, may then require in addition to the revealing screen, the use of a filter. polarizer, which may or may not be present on the article.

The revelation screen 4 can be formed by printing or metallization and / or demetallization.

The blackout raster lines 5a of the revealing raster 4 can be glossy or matt.

As a variant, the revelation screen 4 is different, in particular the lines of the screens are not opaque and transparent. The blackout raster lines can be formed of a filter that does not pass the wavelengths corresponding to the combined image and the non-blackout raster lines can at least partially pass these wavelengths.

Image revealed

The period Q of the revelation frame 4 is equal to the period S of the combined image I.

When the disclosure frame 4 and the combined image I are superimposed and the general orientation O _t of the disclosure frame 4 is substantially the same as the general orientation O _i of the combined image I, a revealed image I _r can be observed. The revealed image I _r then corresponds to the parts of the combined image I present under the lines of transparent frames 5b for a given viewing angle.

Indeed, when the revealing frame 4 and the combined image I are superimposed, under the condition mentioned above and when the revealed images are observed on the side of the revealing frame, the blackout frame lines 5a come to mask part of the lines. of nested images i ₁ to i _n , the other part of the lines of nested images i ₁ to i _n being visible through the transparent raster lines 5b. The lines of transparent frames 5b all allow the visualization of the same proportion (P ₁ ; ...; P _n ) of the nested image lines i ₁ to i _n . The proportion P _i corresponds to the proportion of a line i _i of the visible nested image I _i.

In the case where the superposition is observed from the side of the combined image I, the obscuring raster lines 5a make the nested image lines i ₁ to i _n on which they are superimposed dark and thereby prevent their visualization. Thus only the lines of nested images i ₁ to i _n superimposed on the lines of transparent frames 4b are visible to form the revealed image I _r .

Preferably, the revealed images I _r are observable in reflected light and in transmitted light.

In the example of figures 2A to 2C , the lines of nested images i ₁ to i _n are all of the same width l ₁ to l _n and the shadowing raster lines 5a have a width m equal to 0.75 times the width of the lines of nested images i ₁ to i _n . Thus, the occulting raster lines 5a, when they are well positioned relative to the nested image lines i ₁ to i _n , cover three quarters of one of the nested images, ie three quarters of a color; two nested images and a quarter of the third nested image are therefore visible. In the case of figure 2A , all the blue and green and a quarter of the red are visible and three quarters of the red is hidden, the proportion (P ₁ ; P ₂ ; P ₃ ) of the lines of nested images i ₁ , i ₂ and i ₃ of l The revealed image I _r is (0.25; 1; 1). Likewise for the figure 2B , the proportion (P ₁ ; P ₂ ; P ₃ ) of the nested image lines i ₁ , i ₂ and i ₃ of the revealed image I _r is (1; 0.25; 1) and for the figure 2C , the proportion (P ₁ ; P ₂ ; P ₃ ) of the nested image lines i ₁ , i ₂ and i ₃ of the revealed image I _r is (1; 1; 0.25).

The revealed image I _r can appear homogeneous to the naked eye. In the case of a combined image I in the form of a colored frame formed of an alternation of red, green and blue lines of identical widths l and of a revealing frame of width of transparent raster line k , it is possible to determine the color of the revealed image I _r in RGB coordinates from the proportion (P _R , P _V , P _B ). The RGB coordinates are in the form of three numbers between 0 and 255 characterizing said color, each number each representing the proportion of one of the red, green and blue components making it possible to obtain said color.

$$V=V_{\mathit{max}}\ast P_V,\mathrm{et}$$

$$B=B_{\mathit{max}}\ast P_B,$$

avec $$R_{\max }=V_{\mathit{max}}=B_{\mathit{max}}=255\ast \raisebox{1ex}{$k$}\!\left/ \!\raisebox{-1ex}{$S$}\right.$$

The components have for coordinates: $$R=R_{\mathit{max}}\ast P_R,$$

$$V=V_{\mathit{max}}\ast P_V,\mathrm{and}$$

$$B=B_{\mathit{max}}\ast P_B,$$

with $$R_{\max }=V_{\mathit{max}}=B_{\mathit{max}}=255\ast \raisebox{1ex}{$k$}\!\left/ \!\raisebox{-1ex}{$S$}\right.$$

It is thus possible to determine the color of the revealed image as a function of the width k of the lines of transparent frames 5b and of the proportion (P _R , P _V , P _B ) of the nested images I ₁ , I ₂ and I ₃ .

The revealed image Ir is observable in transmitted light or in reflected light both from the side of the revealing screen 4 and from the side of the combined image I when the revealing screen 4 and the combined image I are superimposed.

In the variant illustrated on figure 35A , the combined image I comprises a periodic alternation of pixels of nested images p ₁ to p _n in two directions X and Y. The pixels of nested images p ₁ to p _n are rectangular in shape but it could be otherwise. For example the pixels could be of another polygonal shape, in particular a square, hexagon or rhombus.

The pixels of the figure 35A can also be seen as lines of diagonal nested images formed of pixels joined together by one of their corners periodically alternating in the Z direction.

The above description, made for lines, applies to pixels. Thus, the pixels p ₁ to p _n belonging to different nested images have a different appearance, in particular a different hue, saturation, brightness, transparency, luminescence. For example the pixels p ₁ to p _n belonging to different nested images are of different colors, in particular red, green and blue.

The combined image I presents in the direction X _I a period Sx and in the direction Y _I a period S _Y. Here, the directions X _I and Y _I are perpendicular but there could be otherwise. The directions X _I and Y _I could form between them a non-zero angle different from 90 °.

The pixels of nested images p ₁ to p _n have a dimension lx and a dimension l _Y according to the directions X _I and Y _{I respectively} . The dimensions l _X and l _Y are each as described above for the nested image lines i ₁ to i _n .

The associated revelation frame 4 is according to the figure 35B . It presents a periodic alternation of blocking frame pixels 5a in two directions X _T and Y _T forming between them the same angle as the directions X _I and Y _I. The blocking frame pixels 5a are separated from each other by transparent intervals 5b and are repeated according to the periods Sx and S _Y of the combined image according to the respective directions X _T and Y _T.

The pixels of the revealing frame can be of a dimension mx and of a dimension m _Y in the respective directions X _T and Y _T less than the periods S _X and S _Y respectively.

In the example illustrated, the dimension mx in the direction X _T is equal to the dimension l _X of the pixels of nested images p ₁ to p _n and the dimension m _Y in the direction Y _T is equal to the dimension l _Y of the nested image pixels p ₁ to p _n

The dimensions m _X and my may be different from l _X and l _{Y respectively,} provided that the periods in the X and Y directions are the same.

When superimposing the revelation frame 4 and the combined image I so that the directions X _T and X _I coincide and the directions Y _T and Y _I coincide, the revelation frame makes it possible to observe revealed images I _r as represented on the figures 35C to 35E .

In the example illustrated, the occulting raster pixels 5a hide one of the nested images I ₁ to I _n so that two of the nested images are visible. On the figure 35C , the revealed image I _r is formed by the nested green and red images, on the figure 35D , the revealed image I _r is formed of the nested blue and red images and on the figure 35E , the revealed image I _r is formed of the nested blue and green images.

The different revealed images I _r illustrated can be obtained by moving the revealing frame 4 relative to the combined image in the direction X _I , the direction Y _I or the direction Z and / or by changing the viewing angle. around the directions X _I and Y _I or Z.

Observation of a change in the revealed image

It is possible to vary the revealed image I _r observed by changing the observation conditions of the revealing frame 4 and of the combined superimposed image I, and in particular, as will be detailed below, by changing the observation angle and / or by moving the revealing frame 4 with respect to the combined image I. Thus, virtually or actually, by moving the combined image I with respect to the revealing frame 4 in a direction X of alternation of the lines of the combined image I and of the revealing frame 4, the revealed image I _r varies.

Thus, by changing the observation conditions, it is possible to switch from figure 2A to the figure 2C .

By varying the observation conditions, the user can then see a change in the revealed image I _r and conclude on the basis of this observation about the authenticity of the article.

Blocks

As shown on figures 3A , 5A and 6A , the revelation frame 4 can be formed from a plurality g of frame blocks B ₁ to B _g . Each frame block B _i is as described for revelation frame 4 in relation to the figures 2A to 2C and makes it possible to reveal, when the revelation frame is superimposed on the combined image I as described above and its orientation is the same, a revealed image I _r1 to I _rg .

Blocks B ₁ to B _g of revelation frame 4 are superimposed on the same combined image I.

Preferably, as illustrated, the blocks B ₁ to B _g of the same frame have the same period Q and the same general orientation O _b . The general orientations O _b of the blocks 10 define a general orientation of the frame Ot.

The blocks B ₁ to B _g have a maximum dimension v of between 1.4 and 42 mm and an area between 0.2 and 90% of the area of the revelation screen.

In the examples shown on the figures 3A , 5A and 6A , the blocks B ₁ to B _g have screen lines 5a of the same width m and at least two of the blocks B _i and B _j are out of phase with each other, that is to say have a non-zero phase shift distance dij less than the period Q, the phase shift distance dij being defined as the remainder of the division of the distance c _ij between the longitudinal axis of a frame line i _i of the block B _i and the longitudinal axis of the line of consecutive frame i _j of block B _j by period Q. $$d_{\mathit{ij}}=\mathit{rest}\left(\raisebox{1ex}{${\mathrm{vs}}_{\mathit{ij}}$}\!\left/ \!\raisebox{-1ex}{$Q$}\right.\right)$$

When the revelation frame 4 is observed so that its general orientation O _t is vertical, at least a part of the screening lines of a block B _i can be above and / or next to at least a part blackout frame lines of another block B _j .

Thus, when the revealing frame is superimposed on the combined image and has the same general orientation, the transparent frame lines 5b of the block B _i do not reveal the same proportion of the nested images (P ₁ ; ...; P _n ) than that of block B _j and therefore the images revealed I _ri and I _rj respectively by blocks B _i and B _j have different aspects because they do not have the same proportion (P ₁ ; ...; P _n ) nested images. In the illustrated case of a combined rasterized and colored image, for example with red, green and blue lines, the revealed images I _r1 to I _rg of the blocks out of phase with one another are of different colors.

Preferably, the revelation frame 4 is continuous and each of the blocks B ₁ to B _g has part of its outline in common with another of the blocks B ₁ to B _g .

The revealed images I _r1 to I _rg can form a pattern, in particular a text, an alphanumeric sign, an ideogram, a geometric shape, an object, a person and / or an animal, for example reproducing a pattern present elsewhere on the article secured.

By changing the conditions of observation of the revealing frame 4 and of the combined image I superimposed, in particular, as is detailed below, by changing the angle of observation and / or by moving the revealing frame 4 compared to the combined image I, the images revealed I _r1 to I _rg by the different blocks B ₁ to B _g can vary. This change in appearance can give the impression of movement or cause the color of a pattern to vary.

The figures 3A to 3F and 5A to 6C illustrate examples of revelation frames 4 formed of blocks B ₁ to B _g superimposed on a combined image.

In these examples, the revelation frame 4 is superimposed on a combined image I formed of three nested images colored respectively in red, green and blue, as described previously.

In the example shown on figures 3A to 3E , the revelation frame 4 comprises six _{rectangular blocks B 1} to B ₆ each forming approximately 1/6 ^th of a rectangle, as can be seen on the figure 3B . Each of the blocks B ₁ to B ₆ has an outline common with at least two other blocks B ₁ to B ₆ . The area of each block B ₁ to B ₆ is substantially between 20% and 15% of the area of the revelation screen 4.

Blocks B ₁ , B ₂ and B ₃ are out of phase with each other and block B ₄ is not out of phase with block B ₁ , block B ₅ is not out of phase with block B ₂ and block B ₆ is not out of phase with respect to block B ₃ so that each of blocks B ₁ to B ₆ is out of phase with respect to blocks B ₁ to B ₆ which are adjacent to it.

As visible on the figure 3F representing the junction of the blocks B ₁ , B ₂ , B ₃ and B ₄ , when the general orientation O _t of the revelation frame is oriented vertically, the blocks B ₁ and B ₃ are arranged one above the 'other and have an edge 6 ₁₃ , shown by dotted lines, in common while the blocks B ₁ and B ₂ are arranged next to each other with an edge 6 ₁₂ in common.

The blackout raster lines of block B ₁ have a corner 9 in common with the blackout raster lines of block B ₃ . It is the same with blocks B ₃ and B ₅ , B ₂ and B ₄ , and B ₄ and B ₆ . As shown on the figure 3F , block B ₁ is phase-shifted from block B ₃ by a phase-shift distance d ₁₃ equal to the width m of a blackout frame line. It is the same with blocks B ₃ and B ₅ , B ₂ and B ₄ , and B ₄ and B ₆ . The distance c ₁₂ between the last blackout frame line of block B ₁ and the consecutive blackout frame line of block B ₂ is equal to five times the width m of a blackout frame line. As the period Q is equal to three times the length m, the block B ₁ is phase-shifted from the block B ₂ by a phase-shift distance d ₁₂ equal to twice the width m of a blackout frame line. It is the same with blocks B ₃ and B ₄ , and B ₅ and B ₆ . The width m of the blackout raster line 5a is equal to the width l of a nested image line so that the transparent raster line can reveal two nested images.

The revealed images I _r1 , I _r2 and I _r3 are out of phase and the respective revealed images I _r1 and I _r4 , Ir ₂ and I _r5 , and Ir ₃ and I _r6 are identical. The revealed images I _r1 to Ir ₆ form a rectangle composed of 6 squares each formed by a revealed image I _r1 to I _r6 , each square being adjacent to squares of different colors. Thus, as shown in the figure 3B , if the nested image I _r1 has proportions of nested images (1; 1; 0), which corresponds to an RGB color (170, 170, 0), then the nested image I _r2 has proportions (1 ; 0; 1), which corresponds to an RGB color (170,0, 170), and the nested image I _r3 has proportions (0; 1; 1), which corresponds to an RGB color (0, 170 , 170).

The figures 3C to 3E represent images revealed I _r1 to I _r6 under different observation conditions.

By changing the viewing conditions, it is possible to switch from figure 3C to the 3d figure and at the figure 3E , which gives the user the impression that the blocks of colors are rotating between them in the direction of clockwise, in particular that I _r1 takes the place of I _r2 which takes the place of I _r4 which takes the place of I _r6 and so on.

In the example shown on figures 3A to 3F , the blocks B ₁ to B _g are distinct zones of the revelation frame 4 which do not overlap. It may be otherwise, in particular due to manufacturing tolerances. The blocks B ₁ to B _g can be in zones of the revealing screen 4 which overlap on less than 5% of the area of the revealing screen.

As a variant illustrated on figure 4A , the blackout frame lines of block B ₁ have a region 11 in common with the blackout frame lines of block B ₃ . In a variant further illustrated on figure 4B , the blackout frame lines of block B ₁ are separate from the blackout frame lines of block B ₃ .

As a variant illustrated on figure 4C , the distance c ₁₂ between the last blackout frame line of block B ₁ and the consecutive blackout frame line of block B ₂ is equal to twice the width m of a blackout frame line.

In the example shown on figures 5A to 5D , the revelation frame 4 comprises sixteen blocks B ₁ to B ₁₆ each forming a disk sector. Each block B ₁ to B ₁₆ is adjacent to two blocks and all the blocks B ₁ to B ₁₆ meet at the center of the disc.

The blocks B ₁ , B ₂ B ₃ and B ₄ are out of phase with each other and the blocks B ₅ , B ₉ and B ₁₃ are not out of phase with the block B ₁ , the blocks B ₆ , B ₁₀ and B ₁₄ are not not out of phase with block B ₂ , blocks B ₇ , B ₁₁ and B ₁₅ are not out of phase with block B ₃ and blocks B ₈ , B ₁₂ and B ₁₆ are not out of phase with block B ₄ so that each of the blocks B ₁ to B ₁₆ is out of phase with respect to the three blocks B ₁ to B ₁₆ which succeed it and which precede it when one turns in the direction of clockwise.

The shading raster lines 5a have a width m substantially equal to three quarters of the width l of the nested image lines.

Block B ₁ is phase-shifted from block B ₂ by a distance d ₁₂ equal to three quarters of the width l of a nested image line i ₁ to i ₄ , block B ₁ is phase-shifted from block B ₃ d ' a distance d ₁₃ equal to three half of the width l of a nested image line i ₁ to i ₄ and the block B ₁ is phase-shifted from block B ₄ by a distance d ₁₄ equal to nine quarters of the width l of a nested image line i ₁ to i ₄ .

The revealed images I _r1 to I _r16 form a disc composed of 16 sectors each formed by a revealed image I _r1 to I _r16 , each sector being situated between sectors of different colors. Thus, as shown in the figure 5B , if the nested image I _r1 presents proportions of nested images (1; 0.25; 1), that is to say an RGB color of approximately (191, 48, 191), then the nested image I _r2 presents proportions (0.5; 0.75; 1), i.e. an RGB color of approximately (95, 143, 191), the nested image I _r3 has proportions (0.5; 1; 0.75), i.e. a RGB color of about (95, 191, 143) and the nested image I _r4 has proportions (1; 1; 0.25), or an RGB color of about (191, 191,48).

The figures 5B to 5D represent images revealed I _r1 to I _r16 under different observation conditions.

Thus, by changing the observation conditions, it is possible to switch from figure 5B to the figure 5C and at the figure 5D , which gives the user the impression that the color blocks are rotating clockwise.

In the example shown on figures 6A to 6C , the revelation frame 4 comprises four blocks B ₁ to B ₄ of different shapes. The block B ₂ represents the number 1, the blocks B ₃ and B ₄ represent the number 0 and the block B ₁ is a rectangular block in which the other blocks are inserted. All the blocks B ₁ to B ₄ are out of phase with one another.

The images are schematic for illustrative purposes however when observing the revelation frame alone shown in the figure 6A , the pattern "100" is not distinguishable at a normal viewing distance, between 30 cm and 10 cm and preferably 15 cm.

The occulting raster lines 5a have a width m substantially equal to three quarters of the width l of the nested image lines, as in the example of figures 5A to 5D .

The revealed images I _r1 to I _r4 form the number 100 on a colored background, the colors of all the numbers being different.

The figures 6B to 6C represent images revealed I _r1 to I _r4 under different observation conditions.

Thus, by changing the observation conditions, it is possible to switch from figure 6B to the figure 6C and observe a color change of the number 100.

In the variant illustrated on figure 9 , at least two blocks B _i and B _j have blackout frame lines of respective widths m _i and m _{j that are} different. Thus, when the revealing frame is superimposed on the combined image so that its general orientation is the same, the lines of transparent frames 5b of the block B _i do not reveal the same proportion of the lines of nested images (P ₁ ; ...; P _n ) than that of block B _j and therefore the images revealed I _ri and I _rj respectively by blocks B _i and B _j do not have the same proportion (P ₁ ; ...; P _n ) nested images. In the illustrated case of a combined rasterized and colored image, for example with red, green and blue lines, the revealed images I _r1 to I _rg of the blocks of widths m ₁ to m _g are of different colors.

1. (i) comme illustré sur la figure 10A, lorsque les lignes de trame occultantes 5a des blocs B_i et B_j se superposent ou ont un bord en commun, une alternance périodique de période Q d'une ligne de trame occultante 15a et d'une ligne de trame transparente 15b, la ligne de trame occultante ayant une épaisseur supérieure ou égale à celle des lignes de trame de chacun des blocs la formant, ou
2. (ii) comme illustré sur la figure 10B, lorsque les lignes de trame occultantes 5a des blocs B_i et B_j sont disjointes, une alternance périodique de période Q de quatre lignes de trames alternativement occultantes 15a et transparentes 15b.

In the variant illustrated on figures 10A and 10B , two blocks B _i and B _j of the same revelation frame 4 are at least partially superimposed. Their superposition defines a sub-block 15 having the form of a frame formed by the interlacing of the frame lines 5a and 5b of the blocks B _i and B _j . The frame of sub-block 15 can have:

1. (i) as illustrated on figure 10A , when the occulting raster lines 5a of the blocks B _i and B _j overlap or have an edge in common, a periodic alternation of period Q of a blackout raster line 15a and a transparent raster line 15b, the line of a blackout frame having a thickness greater than or equal to that of the frame lines of each of the blocks forming it, or
2. (ii) as illustrated on figure 10B , when the occulting frame lines 5a of the blocks B _i and B _j are separate, a periodic alternation of period Q of four lines of frames which are alternately obscuring 15a and transparent 15b.

Each sub-block 15 allows the observation of an image revealed I _r by superposition on the combined image. In case (i), the revealed image is of the same shape as for a block having an occulting raster line of the same width and in the case of image (ii), the revealed image obtained depends on the position and the width of the weft lines 15a and 15b.

As a variant, the combined image I illustrated on figure 11A comprises blocks C ₁ to C ₃ and the revelation frame 4 is in the form of a single block.

The blocks of the combined image are each as described in relation to the figure 1 .

The combined image blocks C1 to C3 are in rectangular form. The blocks C ₁ and C ₂ are out of phase with one another by a width l of a nested image line and the blocks C ₁ and C ₃ are not out of phase with one another.

The revealing screen has lines of opaque screens 5a having a width m equal to the width l of a line i ₁ to i ₃ of nested images.

When superimposing the revealing frame 4 and the combined image I as illustrated on the figure 11B , the revealed images I _r1 and I _r3 are composed of all the red and blue lines and therefore present a proportion (1; 0; 1) of the nested images and the revealed image I _r2 is composed of all the red lines and green and has a proportion (1; 1; 0) of the nested images.

By changing the observation conditions, in particular by moving the revealing frame relative to the combined image in the X direction or by changing the observation angle, the revealed images I _r1 to I _r3 change, for example going from the figure 11B of figures 11C and 11D .

Observation by superposition on either side of a support

We have represented at the figure 12 a first embodiment in which a secure article 10 according to the invention comprises a non-opaque substrate 20, for example perfectly transparent, having a first face 20a carrying the combined image I. The second face 20b of the substrate 2, opposite to the first, carries the weft of revelation 4.

When the secure article 10 is observed from one side or the other of the substrate, the revelation frame 4 makes it possible to observe one or more revealed images I _r . By changing the observation angle α , the user changes the observation conditions and the revealed image (s) I _r are modified as described above.

In order to be able to visualize all the nested images up to an inclination angle of about 45 °, the thickness e of the substrate is preferably greater than or equal to approximately the period Q.

It may be advantageous to have a substrate whose thickness e is less than or equal to 30 μm, better still 25 μm, for example between 20 and 30 μm, or even 20 and 25 μm, limits included or excluded.

Another possibility for varying the direction of observation of the secure article may be to deform the substrate, for example around a folding axis, as illustrated in figure 13 .

Depending on the pattern of the revelation screen 4, it may be necessary to mark the latter with respect to the combined image I in the direction parallel to the general orientation of the latter. For example, for a linear revelation screen such as illustrated in figure 2A , no tracking is necessary; on the other hand, for a wavy frame, a more or less precise registration, depending on the amplitude and the frequency of the corrugations, may prove to be desirable. The invention thus offers a possibility of modular security as a function of the protection requested and the difficulty of implementation.

For secure articles comprising a thread introduced in window (s), the combined image I can be obtained by micro-photolithography of the thread and the revelation screen 4 can be produced by means of offset printing with inks crosslinking under UV carried out in a second step, when printing the article.

The revelation screen 4 can be associated, where appropriate, with a print pattern of the article.

The pattern of the revelation screen 4 can be printed elsewhere than in superposition with the combined image I, on the article, at the same scale or at a different scale.

The printing of the revelation screen 4 may extend beyond the combined image I and extend over the secure article 10, as illustrated in figure 14 .

Several revelation screens and combined images, having for example the shape of small squares or rectangles with a side of a few millimeters, can be present on the same security thread 30, as illustrated in figure 15 .

When the revelation screen 4 and the combined image I are on a wire integrated in window (s), as illustrated in figures 16A and 16B , the secure article 10 may include at least two windows 31 and 32 allowing each of the faces of the wire to be observed respectively, in reflection.

The article may include, at the level of the windows 31 and 32, gaps in material and transparent zones 35 and 36 allowing the observation of the images revealed on both sides of the secure article 10.

The nested images are observable through the reveal screen 4 on the side of the window 31 and with the reveal screen as a background, on the side of the window 32.

The article 10 may also include a through window 31, as shown in figure 16D , the revelation frame 4 and the combined image I being located at least partially in this through window. In this way, it is possible to observe the images revealed on both the front side and the back side of the secure article 10.

The disclosure frame 4 and the combined image in the form of a security thread can still be incorporated into a secure article 10 which have alternating windows 31 and 32 on the front side and on the back side, as illustrated in figure figure 16C . It is thus possible to observe the images revealed both on the front side and on the back side of the secure article 10 at the level of the windows 31 and 32, and in particular due to the presence of the shortages of material and of the transparent zones 35. and 36.

We have represented on the figure 17 an example of a secure article 10 comprising a perforation 40 in which are placed at least partially two sub-elements, in particular in the form of foils or patches, 41 and 42.

The sub-element 41 comprises for example a revelation frame 4 and the sub-element 42 comprises for example the corresponding combined image I.

The sub-elements 41 and 42 can be superimposed at least partially on the edges of the perforation 40 with or without a thickness compensation.

The sub-elements 41 and 42 can be at least partially transparent or translucent.

The observation of the revealed images can be done by observation in reflection or in transmission, for example using a light source located behind the article 10 during the observation.

In the variant illustrated on figure 18 , the secure article 10 comprises a combined image I produced in the form of impressions. The prints are for example made on the surface of the secure article 10. In addition, a sub-element 43, in particular in the form of a foil or patch, is placed on the prints constituting the combined image I, the sub-element 43 comprising the corresponding revealing screen 4, for example produced on the surface of the sub-element 43.

The secure article 10 may or may not be opaque. The secure article 10 can be at least partially transparent or translucent to allow observation of the nested images, in particular on the side of the combined image I.

In the examples of figures 17 and 18 , the revelation screens 4 and / or the combined images I could be produced differently, for example being incorporated or located above or below the sub-elements 41, 42 and 43.

As a variant, the combined image comprises two metallizations of different colors each corresponding to a nested image, in particular a nested copper image and a nested aluminum image.

As a further variant, the combined image comprises at least two metallizations, in particular of the same color, of different optical densities each corresponding to a nested image, thus creating a brightness contrast.

The nested aluminum image can be of high optical density, which makes it look shiny.

The revelation screen 4 may have a matt appearance.

The superposition of the combined image I and of the revelation screen 4 makes it possible to obtain, according to the blocks B ₁ to B _g , dull or shiny revealed images I _r1 to I _rg. A displacement of the revealing frame 4 relative to the combined image I along the X axis can make it possible to reverse the appearance of the revealed images I _r1 to I _rg at the level of the different blocks B ₁ to B _g , c ' that is to say that the revealed images I _r1 to I _rg which were bright can become dull and vice versa.

Observation by folding the document or superimposing the document and another object

In a second embodiment, illustrated in figure 19 , the secure article 10 comprises a window 50, preferably at least partially transparent, in which appears the revelation frame 4. The article 10 also comprises a combined image I carried on the article 10, for example by printing, in particular intaglio printing, offset printing or metallization and / or demetallization. The zone in which the combined image 2 appears can also be at least partially transparent.

To observe the revealed image, the user must therefore fold the secure article 10, as illustrated in figure 20 , to bring the revelation frame 4 back to the combined image I so that their general orientation is the same and observe the image (s) revealed I _r . Thus, the revealed images are not visible when the article 10 is not folded and it takes user action, namely folding the secure article 10, to make them appear.

On the figure 21 , the secure article 10 comprises a window 50, preferably at least partially transparent, in which appears the combined image I. The article 10 also comprises a patch 55 comprising for example holographic prints, on which the revelation screen appears. 3. The patch 55 can also be at least partially transparent.

The patch 55 may include metallizations and / or demetallizations, for example made of aluminum, and the revelation screen 4 may include holographic impressions and / or metallizations and / or demetallizations.

On the figure 22 , article 10 comprises a window 50, preferably at least partially transparent, in which appears the revelation screen 4. Article 10 also comprises a security thread 60 on which appears the combined image I. The security thread 60 can also be at least partially transparent or include a partially transparent zone at the level of the combined image I.

We have represented on the figures 23 to 27 other examples of secure articles 10 according to the invention comprising a combined image I and a revelation frame 4 conforming to those of figures 19 to 21 , the combined image I and / or the revelation frame 4 being carried by at least one security thread or one foil.

On the figure 23 , article 10 comprises a security thread 60 of sufficient width to alternately display combined images I and revelation screens 4. Advantageously, the security thread 60 is at least partially transparent or has one or more zones. at least partially transparent at the level of the combined images I and / or of the revealing frames 4.

On the figure 24 , article 10 comprises a security thread 60 on which appears a revelation screen 4. Article 10 also comprises a combined image I, for example in the form of an offset printing on article 10.

The security thread 60 can be at least partially transparent or have an at least partially transparent zone. The article 10 can also include an area at least partially transparent at the level of the combined image I.

On the figure 25 , article 10 has two security threads 60a and 60b. The security thread 60a comprises three combined images I and the security thread 60b comprises three revelation frames 4.

The security thread 60a and / or the security thread 60b can be at least partially transparent or comprise at least one at least partially transparent zone, in particular at the level of a combined image I or of a revelation screen 4.

On the figure 26 , article 10 comprises a foil 70 on which appears an alternation of combined images I and revelation frames 4.

The foil 70 can be at least partially transparent or comprise at least one zone at least partially transparent at the level of a combined image I and / or of a revelation frame 4.

On the figure 27 , article 10 comprises a security thread 60 on which appears a combined image I. Article 10 also comprises a patch 55, which may or may not include holographic metallizations, on which appears a revelation screen 4.

The security thread 60 can be at least partially transparent or include an at least partially transparent zone at the level of the combined image I.

The patch 55 can also be at least partially transparent, in particular at the level of the revelation screen 4.

In all the examples described above, the combined images I and the revealing frames 4 can be inverted.

The at least partially transparent zones can be situated at the level of the combined images I or of the revealing means 4, or at the level of both at the same time.

The security thread (s) 60, 60a and 60b can be introduced into the secure article 10 in a conventional manner, for example on the surface, in bulk or in window (s).

Authentication of the articles 10 can be accomplished by folding them 10 lengthwise or crosswise so as to at least partially overlap the combined images I and disclosure screens 4, and then moving relatively relative to each other. others so as to visualize, for example, the illusion of movement and / or by modifying the angle of observation of the combined images I and of the superimposed revelation screens 4.

As a further variant, it is also possible to at least partially superimpose article 10 with another similar article, as described above.

Two revelation frames with blocks

As shown on figures 28A to 28F , the article or the assembly can comprise two revelation frames 4a and 4b as described above being superimposed on the same combined image I.

The two revelation frames are preferably of different general orientations O _ta and O _tb forming between them a non-zero angle β , preferably between 0 ° and 180 °, limits excluded, better still between 10 and 30 °, for example here substantially equal to 20 °.

• lorsque l'image combinée I est orientée avec l'orientation générale O_ta, les images révélées I_r1a à I_rga de la première trame de révélation 4a au niveau des blocs B_1a à B_ga sont visibles et les images révélées I_r1b à I_rub de la deuxième trame de révélation 4b au niveau des blocs B_1b à B_ub ne sont pas visibles du fait de la présence d'un phénomène de Moiré, et
• lorsque l'image combinée I est orientée avec l'orientation générale O_tb, les images révélées I_r1b à I_rub de la deuxième trame de révélation 4b au niveau des blocs B_1b à B_ub sont visibles et les images révélées I_r1a à I_rga de la première trame de révélation 4a au niveau des blocs B_1a à B_ga ne sont pas visibles du fait de la présence d'un phénomène de Moiré.

The fact that the revelation frames have different general orientations allows given observation conditions that:

• when the combined image I is oriented with the general orientation O _ta , the revealed images I _r1a to I _rga of the first revealing frame 4a at the level of the blocks B _1a to B _ga are visible and the revealed images I _r1b to I _rub of the second revelation frame 4b at the level of the blocks B _1b to B _ub are not visible due to the presence of a Moiré phenomenon, and
• when the combined image I is oriented with the general orientation O _tb , the images revealed I _r1b to I _rub of the second revelation frame 4b at the level of the blocks B _1b to B _ub are visible and the images revealed I _r1a to I _rga of the first revelation frame 4a at the level of blocks B _1a to B _ga are not visible due to the presence of a Moiré phenomenon.

Thus, depending on the orientation of the combined image I with respect to the revealing frames 4a and 4b, one or the other or none of the revealed images is visible, which makes it possible to have increased security.

To observe the images revealed by one or the other of the frames, the user must therefore superimpose the combined image I and the revealing frames 4a and 4b by folding article 10 or superimposing article 10 and of another object and rotate the combined image I with respect to the revealing frames 4a and 4b. The user can also move them relative to each other along an axis perpendicular X to the general orientation of the combined image to observe a change in the image (s) revealed in one of the frames.

The two revelation frames 4a and 4b may or may not be separated from each other. Preferably, the disclosure frame 4b is an inclusion in the disclosure frame 4a.

In the example shown on figure 28B , the first revealing frame 4a is square in shape and is formed of 17 blocks B _1a to B _17a , in particular a central block B _1a of substantially square shape flanked by 16 side blocks B _2a to B _{17a also} of square shape. 12 side blocks B _2a to B _13a are juxtaposed all around the central block B _1a to form a square of width equal to twice the width of the central block B _1a and 4 side blocks B _14a to B _17a ) are each superimposed completely in two 12 side blocks B _2a to B _13a respectively to blocks B _3a and B _4a , B _6a and B _7a , B _9a and B _10a , and B _12a and B _13a . The blocks B _1a to B _17a are all substantially square in shape. The side blocks B _2a to B _17a are of width substantially equal to half the width of the central block B _1a . The superposition of the side blocks B _14a to B _17a on the other side blocks B _2a to B _13a allows the formation of 8 sub-blocks as described above. Each lateral block B _2a to B _13a is out of phase with respect to the lateral block B _2a to B _13a which precedes it and which succeeds it. The side blocks B _2a , B _5a , B _8a and B _11a forming the corners of the revealing screen 4 are not out of phase with each other and are not out of phase with respect to the central block B _1a .

The second revelation frame 4b is rectangular in shape and it is formed of 4 blocks B _1b to B _4b of different shapes. Block B _2b represents number 1, blocks B _3b and B _4b represent number 0 and block B _1b is a rectangular block in which the other blocks are inserted. The blocks B _2b to B _4b are not out of phase with one another but are out of phase with respect to the block B _1b .

The two revelation frames 4a and 4b have respective general orientations O _ta and O _{tb which are} different and form between them an angle β substantially equal to 20 °.

The occulting raster lines 5a have a width m substantially equal to three quarters of the width l of the nested image lines, as in the example of figures 5A to 5D .

The revelation screens 4a and 4b are superimposed on the same combined image I, illustrated on the figure 28A .

As visible on the figures 28C and 28D , when the combined image is oriented in the same direction as the first revelation frame 4a, blocks B _1a to B _17a reveal revealed images I _r1a to I _r21a forming a central square I _r1a surrounded by squares smaller I _r2a to I _r21a of different colors. The color of the small squares I _r2a , I _r5a , I _r8a and I _r11a in the corners is the same as that of the central square I _r1a . The second revelation frame 4b does not form any visible image due to a Moiré phenomenon between the lines of the second revelation frame 4b and the lines of the combined image I.

The figures 28C and 28D represent images revealed under different observation conditions but always with the same orientation of the revelation frames 4a and 4b and of the combined image. The color of the revealed images changes.

As visible on the figures 28F and 28G , when the combined image is oriented in the same direction as the second revealing frame 4b, the revealed images I _r1b to I _r4b form the number 100 on a colored background, the colors of all the numbers being identical. The first revelation frame 4a does not form a visible image due to a Moiré phenomenon between the lines of the first revelation frame 4a and those of the combined image I.

The figures 28E and 28F represent images revealed under different observation conditions always with the same orientation of the revelation frames 4a and 4b and of the combined image. The color of the revealed images changes.

As shown on the figure 28E , the superposition of the revelation frame 4 and of the combined image I can be done by folding the secure article 10 and the change of orientation can be done by rotating the part of the secure article 10a carrying the combined image I with respect to the part of the secure article 10b bearing the revelation frame 4.

Imager

We have represented on the figures 29 to 31 examples of association between a secure article 10 and an electronic imager 100 making it possible to form the revelation frame 4 or the combined image I.

On the figure 29 , the electronic imager 100 is for example a computer screen on which is displayed a first image 110, the first image 110 being the revealing frame 4 or the combined image I.

The secure article 10 is for example in the form of a banknote and comprises a second image 120, the second image being the revealing frame 4 if the first image is the combined image and vice versa.

The secure article 10 is placed on the screen of the electronic imager 100 so as to at least partially superimpose the first image 110 on the second image 120 in order to observe the revealed image (s) I _r and to deduce therefrom authentication information. and / or identification of the secure article 10.

The secure article 10 can be moved relative to the screen of the electronic imager 100 or the observer can change the viewing angle to allow observation of a change in the revealed image (s) I _r .

As a variant, the secure article 10 remains stationary relative to the screen of the electronic imager 100 and the first image 110 is animated by a movement on the screen, for example a translation, for example using 'a program activated or not by the user.

On the figure 30 , the electronic imager 100 is for example in the form of a digital projector, projecting a first image 110 on a background 150, for example the wall of a room.

The secure article 10 comprising the second image 120 can then be superimposed at least partially on the first image 110 projected onto the background 150 to allow the observation of the revealed image (s) I _r .

On the figure 31 , the electronic imager 100 is a projector which projects the first image 110 directly onto the secure article 10.

The first image 110 can, as in the example of the figure 31 , be projected, for example in the form of a “W”, onto an area of the secure article 10 where the second image 120 is not present. Then, the secure article 10 is for example folded on itself so in superimposing the second image 120, for example in the form of an “A”, on the first image 110 projected by the electronic imager 100. The part of the secure article 10 comprising the second image 120 can in particular be folded over the part comprising the first image 110, this part remaining stationary, so that the first image 110 is situated between the imager 100 and the second image 120.

In a variant, not shown, the first image 110 is projected directly onto the second image 120 of the article 10. In particular, the projection of the first image 110 onto the second image 120 of the article 10 can allow superimposition on the surface. less partial of the first and second images. Then, the imager electronics 100 can be moved relative to item 10 to move revealing frame 4 relative to combined image I.

We have represented at the figure 32 an alternative embodiment in which the electronic imager 100 is a screen displaying several first images 110a, 110b, 110c and 110d.

The first images 110a to 110d can have different properties, for example different shapes, colors, dimensions, frame elements.

Advantageously, the first images 110a to 110d are differentiated so as to allow at least one of them to be associated with at least one second image 120 present on an article 10. In this way, it is for example possible to authenticate and / or identify a greater variety of articles 10 having different respective second images, corresponding to the different first images 110a to 110d.

As a variant, the article 10 comprises several second different images 120, as can be seen for example on the figure 15 , and the electronic imager 100 produces one or more first images 110. In this way, it is possible to authenticate and / or identify a given security article 1 on a greater variety of different electronic imagers, and in particular with electronic imagers having different resolutions. In this way, the two aforementioned advantages can be combined.

The electronic imager 100 can display one or more indicators 140a, 140b, 140c and 140d making it possible to inform the user on how to position the article 10 shown on the diagram. figure 33 relative to the imager.

In particular, the indicators 140a to 140d can make it possible to know where to position the upper right corner of the article 10, so as to correctly superimpose a second image 120 of an article 10 on a first displayed image 110a, 110b, 110c or 110d. on the screen of the electronic imager 100.

The article 10 can comprise an integrated microcircuit 152, for example an RFID or optical chip, making it possible to communicate with the electronic imager 100 in order to control the display of an indicator as described above or to broadcast information on the manner to position the first and second images.

As a variant, the chip 152 is able to communicate with the electronic imager 100 to make it possible to produce the first image 110 associated with the second image 120.

In particular, during the authentication and / or identification process of article 10, the second image 120 is illuminated with the electronic imager 100. The chip 152 comprises information transmitted to the electronic imager 100 which projects or then displays the first image 110 based on this information.

The article 10, in particular the second image 120, can be photographed and / or filmed by a digital camera belonging to or linked to the electronic imager 100. A recognition program can then make it possible to recognize the second image 120 and to acquire from there. a database a first image 110 associated with the second image 120. The database is for example stored on a secure server. The first image 110 thus obtained is displayed and / or projected by the electronic imager 110 to make it possible to authenticate and / or identify the article 10.

In the variant illustrated on figure 34 , the electronic imager 100 is in the form of a portable telephone on which is displayed a first image 110 in the form of a combined image I. The article 10 comprises a polarizing filter on which the second image 120 has been formed under form of revealing frame 4. The article 10 comprising the second image 120 in the form of revealing frame 4 is superimposed on the first image 110 in the form of combined image I produced by the electronic imager 100, the latter emitting a polarized light.

The article 10 comprising the revealing screen 4 can be moved by a translational movement along the X axis relative to the combined image I displayed by the screen of the electronic imager 100, so as to change the or the images revealed I _r .

Such a method makes it possible to authenticate and / or identify the security article 1 according to several security levels.

The positioning of the revelation screen 4 comprising the polarizing filter according to the orientation making it possible to observe the opacity of the polarizing filter, this observation being visible only on a screen emitting polarized light, for example a screen of the LCD type, provides a first level of security.

The revelation of the animation of the images revealed by displacement of the revelation frame 4 relative to the combined image I provides a second level of security.

As a further variant, the electronic imager 100 is a screen, in particular of the LCD type, comprising a plurality of pixels preferably forming a combined image, for example as described in figure 35A .

The invention is not limited to the examples illustrated. The secure article can be made with other first, second or third level securities, for example.

The expression “comprising a” should be understood as being synonymous with “comprising at least one”.

Claims (14)

1. Secure article (10) comprising a revelation screen (4) and a combined image (I), or assembly comprising a secure article (10) and another object (100), the secure article (10) comprising one of the revelation screen (4) and the combined image (I) and the object (100) comprising or forming the other of the revelation screen (4) and the combined image (I),

   the combined image (I) being composed of a plurality of interleaved images (I₁ to I_n),

   the combined image (I) comprising a periodic alternation in a first direction (X; X_I, Y_I), of interleaved image elements (i₁ to i_n; p₁ to p_n), the elements (i₁ to i_n; p₁ to p_n) belonging to one and the same interleaved image (I₁ to I_n) being of the same colour and the elements (i₁ to i_n; p₁ to p_n) belonging to different interleaved images (I₁ to I_n) being of different colours, the colorimetric difference ΔE*94 according to IEC 1994 of the interleaved image elements (i₁ to i_n; p₁ to p_n), belonging to different interleaved images (I₁ to I_n), being greater than or equal to 2,

   the revelation screen (4) comprising a periodic alternation in a second direction (X; X_T, Y_T) of an occulting screen element (5a) with a non-occulting screen element (5b),

   the dimension in the second direction (X; X_T, Y_T) of the non-occulting screen elements (5b) being greater than the dimension in the first direction (X; X_I, Y_I) of at least one interleaved image element (i₁ to i_n; p₁ to p_n),

   the period (Q) of the revelation screen (4) in the second direction (X; X_T, Y_T) being equal to the period (S) of the combined image (I) in the first direction (X; X_I, Y_I), the revelation screen (4) making it possible, when it is overlaid on the combined image (I), the first direction and the second direction being aligned, to observe revealed images (I_r; I_r1 to I_rg; I_r1a to I_rga, I_r1b to I_rub) of different colours by displacement of the revelation screen (4) with respect to the combined image (I) and/or by changing the angle of observation, the revealed images being formed by the interleaved image elements being superimposed with the non-occulting screen elements, the revealed images (I_r; I_r1 to I_rg; I_r1a to I_rga, I_r1b to I_rub) each appearing, to the naked eye at a normal observation distance, to have a solid colour, the colour of each revealed image being defined by the proportions of each interleaved image being superimposed on the non-occulting screen elements.
2. Article or assembly according to Claim 1, at least one revealed image (I_r; I_r1 to I_rg; I_r1a to I_rga, I_r1b to I_rub) consisting of at least two adjacent interleaved images.
3. Article or assembly according to Claim 1 or 2, the revelation screen (4) comprising a periodic alternation of an occulting screen element (5a) with a non-occulting screen element (5b) in several directions (X; X_T, Y_T), the occulting screen element (5a) and the non-occulting screen element (5b) being preferably of different opacities, transparencies and/or hues.
4. Article or assembly according to any one of the preceding claims, the combined image (I) comprising a periodic alternation of interleaved image elements (i₁ to i_n; p₁ to p_n) in several directions (X; X_T, Y_T) .
5. Article or assembly according to any one of the preceding claims, the elements (i₁ to i_n; p₁ to p_n) belonging to different interleaved images (I₁ to I_n) being different by their aspects, notably their hues, opacities, saturations, luminescences or brightnesses, preferably the elements (i₁ to i_n; p₁ to p_n) belonging to different interleaved images (I₁ to I_n) being of different hues, the combined image (I) comprising three interleaved images (I₁, I₂, I₃) of preferably primary colours, notably of respective red, green and blue colours.
6. Article or assembly according to any one of the preceding claims, the interleaved image elements (i₁ to i_n; p₁ to p_n) being of dimensions (l) in the or each of the directions (X; X_T, Y_T) less or equal to 1 mm, better less than or equal to 100 µm, even better less than or equal to 50 µm.
7. Article or assembly according to any one of the preceding claims, the interleaved image elements (i₁ to i_n) and the screen elements (5a, 5b) being of the same general form.
8. Article or assembly according to any one of the preceding claims, the combined image (I) having a resolution greater than or equal to 800 dpi.
9. Article or assembly according to any one of the preceding claims, it being arranged such that the revealed images (I_r) are observable in reflected light and/or in transmitted light and/or being arranged such that the revealed images (I_r) are observable both on the side of the revelation screen (4) and on the side of the combined image (I).
10. Article or assembly according to any one of the preceding claims, the revealed images (I_r) forming macropatterns exhibiting different aspects, notably different colours and/or brightnesses, for example different RGB coordinates and/or different patterns, notably the various steps of a movement.
11. Article or assembly according to any one of the preceding claims, at least one of the combined image (I) and of the revelation screen (4) being included on a zone of the secure article (10) or of the object that is at least partially transparent, the overlaying of the revelation screen (4) and of the combined image (I) being performed by folding of the secure article (10) or by overlaying of the secure article (10) with the other object, the revelation screen (4) making it possible, when overlaid at least partially on the combined image (I) of the secure article (10) or of the other object (100), to observe different revealed images (I_r) by a relative displacement of the revelation screen (4) with respect to the combined image (I) and/or by changing the angle of observation of the revelation screen (4) and of the combined image (I).
12. Article according to any one of the preceding claims, the revelation screen (4) and the combined image (I) being overlaid while being separated from one another by a gap of constant thickness, the gap being notably formed by a transparent or translucent substrate (20) presenting, on the side of a first face of the substrate (20a), the combined image (I), and, on the side of a second face of the substrate (20b), opposite the first, the revelation screen (4) overlaid on the combined image (I), the article or assembly being preferably arranged such that the revelation screen (4) makes it possible to observe different revealed images (I_r; I_r1 to I_rg; I_r1a to I_rga, I_r1b to I_rub) upon a change of angle of observation of the secure article.
13. Assembly according to any one of Claims 1 to 11, the other object being an electronic imager (100) making it possible to form a first image (110), the first image (110) being the revelation screen (4) or the combined image (I), to be able to overlay it on a second image (120) of the secure article (10), the second image (120) being the other of the revelation screen (4) and of the combined image (I).
14. Method for authenticating a secure article (10) according to any one of the preceding claims, wherein the image (I_r) revealed by the revelation screen (4) is observed, the angle of observation and/or the position of the revelation screen (4) with respect to the combined image (I) is changed to observe a change of the revealed image (I_r) and a conclusion is drawn as to the authenticity of the article (10) in light of the change of observed image.

Images