The present invention relates to cosmetic articles to be applied to human keratin materials, especially the nails, lips or skin, with a view to creating novel optical effects.

Many cosmetic articles have been developed, the purpose of which is to make a region of the body or of the face more attractive, for example by creating an impression of relief or of change of appearance during a relative movement between the observer and the person who is wearing the article.

Thus, makeup compositions have been developed which comprise goniochromatic coloring agents that produce a color change as a function of the viewing angle. These goniochromatic coloring agents are based on the use of interference structures.

There is a need to develop other means, which are simple to manufacture and to use, which give an attractive result, for example by conferring an impression of increased volume or by creating other makeup or decorative effects.

The invention achieves this objective by virtue of a cosmetic article to be applied to human keratin materials, especially the nails, lips or skin, in particular that of the eyelids, comprising a cosmetically acceptable support, bearing an optical structure comprising an array of lenses or of mirrors and/or a raster, this optical structure being configured so as to enable the perception of at least two different images when the viewing direction changes, these at least two images being composed of individual patterns present on the article or on the keratin materials.

The invention, by suitably choosing the various images that will be observed with the aid of the optical structure, makes it possible to create an impression of relief, of movement or of change of appearance, for example by making it possible to observe a color change, an animation or a moire effect, when the viewing direction changes.

The individual patterns are preferably borne by the article. Thus, the use of the article is facilitated, and may be limited to a simple application, on the human keratin materials, of the article. The individual patterns may be printed or produced by other means, for example by transfer, by etching or by a photographic technique. The process used for producing the individual patterns may depend on the desired resolution.

The support is preferably a transparent, advantageously flexible, film, preferentially made of a thermoplastic material, especially chosen from polystyrene (PS), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene (PE), polypropylene (PP) and mixtures thereof.

The optical structure may comprise an array of lenses, advantageously that are non-cylindrical, in particular spherical, aspherical, polyhedral such as pyramidal, or polygonal-based, for example hexagonal-based. The use of non-cylindrical lenses may be preferred in that it makes it possible to produce an optical structure that is less rigid and therefore more easily able to adopt the relief of the typically non-planar surface to which the article is applied.

The structure may comprise at least two adjacent lenses joined at their base or over at least one part of their height. This makes it possible to increase the number of lenses per unit length, in at least one direction. This is, for example, between 20 and 5000 lenses per cm, with diameters for example between 2 and 500 μιη, better still between 40 and 500 lenses per cm, with diameters for example between 20 and 250 μιη.

In one implementation example of the invention, the structure thus comprises polygonal-based lenses, at least one lens, and better still all the lenses, having their sides joined with a respective side of an adjacent lens.

The lenses may be produced by molding or printing, for example by successive passes according to the technique disclosed in WO 2009/147353.

The lenses are preferably convex and convergent, it being possible for the individual patterns to be located in the focal plane of the lenses.

The individual patterns may be positioned between a background layer borne by the support and the array of lenses. This background layer may be a flat color tint. This may make it possible to create shifting patterns on a colored background.

The optical structure may comprise an array of mirrors and the individual patterns may be located between the observer and the array of mirrors. As a variant, the optical structure may also comprise a raster positioned so as to enable observation, via a parallax effect, of said images when the viewing direction changes. Irrespective of the way in which the optical structure is produced, with an array of lenses or of mirrors that are non-cylindrical or with a raster, the optical structure and the individual patterns may be arranged so as to make it possible to observe a change of image observed not only when the observer moves about a first reference axis but also when the observer moves about a second reference axis, perpendicular to the first. In this case, the individual patterns may be positioned as sub-assemblies that are repeated in two directions that are perpendicular to one another. As a variant, the images only change when the observer moves about a single reference axis, which is the case in particular when cylindrical lenses are used. In this case, the individual patterns may be positioned as sub- assemblies that are repeated in one direction, which may be perpendicular to said single reference axis about which the observer turns in order to successively perceive the various images.

The support may be arranged in order to be applied to the nail, the eyelid or the lips. The support may be adhesive, in particular coated, on its face intended to come into contact with the keratin materials, with an adhesive, preferably that is hypoallergenic.

The images observed with the aid of the optical structure may be arranged in order to accentuate the relief, perceived by the observer, of the keratin materials on which the article is placed. For example, the brightness of the various zones of the article may change with the viewing angle in the same way as would be observed if the underlying surface of the keratin materials had a more pronounced curvature. As a variant, the images are arranged in order to create an animation or a moire effect when the viewing direction changes. A moire effect may interfere with the perception of the relief by the observer and lead the latter to consider that the relief is greater than it actually is.

The images may comprise gradations, in particular of color and/or of brightness, in particular a color gradation of the nails, lips or eyelids. This gradation may give the observer an impression of volume, where appropriate. For example, the lips, due to the presence of the article thereon, appear fuller than they actually are. As a variant, the images may each represent a makeup outline, the outline varying from one image to the next, for example in order to vary the appearance of a line drawn on the eyelid when the viewing direction changes, in particular a line imitating the application of eyeliner.

Certain images that appear at different viewing angles may be identical. For example, the images observed are the same for viewing directions that are symmetrical to one another relative to the normal to the article. Thus, the individual patterns may be positioned as sub-assemblies that are repeated with a symmetrical arrangement of the individual patterns within the sub-assemblies relative to the individual pattern which is observed under normal incidence, that is to say that the individual patterns may be the same for the rows i-m and i+m, if i denotes the row corresponding to normal incidence.

The individual patterns may each be a flat color tint or flat grey tint.

The number of images that may be perceived when the viewing direction changes is preferably greater than or equal to 3, for example being between 3 and 10.

The individual patterns may be grouped together in sub-assemblies which are for example identical and are repeated in at least one direction of the article, or as a variant differ depending on the location on the article. Each sub-assembly may be combined with a single respective lens, in particular in the case where the optical structure consists of a lenticular array.

The individual patterns may each have an elongated shape, for example being of rectangular contour. The longitudinal direction of the patterns may be parallel to the generatrices of the lenses when the optical structure is an array of cylindrical lenses, or parallel to the lines of the raster in the case of the use of a raster.

When the optical structure is composed of non-cylindrical lenses, and when the individual patterns are repeated in a direction perpendicular to a reference axis about which the observer must turn in order to perceive the change of image, the individual patterns may have a shape that is elongated in this direction.

In particular in this case, two individual patterns belonging to one and the same sub-assembly may be offset in the direction of their length. For example, all the individual patterns are gradually offset when the row increases by a distance which corresponds to a fraction of their length, in accordance with the teaching of the publication WO 98/20392.

Adjacent individual patterns are preferably juxtaposed and touching. Two adjacent individual patterns which are touching may belong to one and the same subassembly, being of rows j and j+1, or to different sub-assemblies, being of extreme rows in these sub-assemblies.

The thickness of the article is preferably between 0.5 and 3000 μιη.

In order to produce the article, the latter is for example cut to the desired shape, either by the manufacturer of the article, or by the user. The article may comprise a layer of a pressure-sensitive adhesive which is covered before the use of the article with a removable protective film, for example a silicone-coated paper.

Another subject of the invention is a makeup method, comprising the step consisting in applying to the human keratin materials an optical structure according to the invention, comprising an array of lenses or of mirrors and/or a raster, this optical structure producing various images depending on the viewing direction, these images being composed of individual patterns present on the human keratin materials or on a support placed on said human keratin materials.

The individual patterns may be printed directly onto the human keratin materials, but preferably the individual patterns are borne by a support added onto the human keratin materials, which facilitates the implementation of the method.

The optical structure may comprise an array of lenses and/or a raster produced in situ on the human keratin materials. Preferably, the optical structure is present on an article, as defined above, added onto the human keratin materials, and held thereon for example with the aid of an adhesive.

In one implementation example of the method, a colorimetric acquisition of the human keratin materials is carried out, and the individual patterns are produced as a function of said acquisition, in particular so that at least one of said individual patterns has the same color as the color thus acquired. This may make it possible to imitate as best as possible the natural color of the nails, lips or skin, at least for certain regions of the images observed by virtue of the optical structure. The presence of the article may then be more difficult to detect. It is also possible to measure the dimensions of the surface intended to receive the article, in order to adapt the dimensions of the article to that of the surface that will receive it. The article may then be supplied to the user with a personalized size.

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

figure 1 illustrates an example of an article according to the invention, intended to be applied to the nail,

- figure 2 shows the detail II from figure 1,

figure 3 is a schematic cross section of the article from figures 1 and 2, figure 4 illustrates an example of the placement of the individual patterns on the article, and the corresponding images observed,

figures 5 to 7 are views similar to figure 4 of variant embodiments of the article,

- figures 8 to 10 are views similar to figure 3 of variant embodiments of the optical structure, and

figures 1 1 to 14 illustrate examples of images perceived as a function of the viewing direction, for examples of articles according to the invention.

The article 1 according to the invention, represented in figures 1 to 4, is intended to be applied to a nail O, as illustrated, however the description which follows is also valid for articles intended to be applied to other surfaces of the body or of the face, especially the lips and the eyelids.

The article 1 comprises an optical structure 10 that makes it possible to produce, when observed, various images depending on the viewing direction.

Several configurations make it possible to obtain this result, based for example on the use of a lenticular array, mirrors or a raster.

In the example illustrated in figure 1 , the optical structure 10 is formed by a lenticular array comprising a plurality of microlenses 1 1 , represented schematically in figures 2 and 3.

In the example from figures 1 to 3, the lenses are non-cylindrical, being spherical for example, but the invention is not limited to a particular lens shape. A non- cylindrical shape is nevertheless particularly preferred, since it imparts less rigidity to the article.

Many publications describe lenticular arrays and the well-known rules of geometrical optics which are applicable in the design of lenses, the lenticular arrays already being used in many fields other than cosmetics. Reference may usefully be made to the publications WO 98/20392, WO 2009/147353, WO 201 1/151536, which give examples of processes for manufacturing arrays of lenses and arrangements of individual patterns that may be taken up in order to produce an article according to the invention.

The lenticular array is positioned on top of an assembly 13 of individual patterns 131 , .. . 13 _n , where n is equal to the number of different images, Ii , .. . , I _n that may be observed, n being equal to 5 in the example from figures 1 to 3. The individual patterns are said to be of row i when they belong to an i image, Ii that can be observed by virtue of the optical structure 10.

The image of row 1 corresponds to that observed for a certain angle a about a reference axis of the structure 10 and the images of the following rows 2, ... , n correspond to the various images that can be observed on turning about this reference axis and when the angle a increases.

The assembly 13 of individual patterns may be composed of several subassemblies 13' comprising an individual pattern 131 ... 13 _n of each row. Preferably, all the patterns 13 _j of a same row j belong to a same image I _j observed using the optical structure 10. The various images observed Ii, ... , I _n are thus composed of individual patterns and are overlapped with one another within the assembly 13. The latter may be formed by printing or by other means, preferably on the face of the substrate bearing the lenses on the opposite side thereto. This substrate may be a flexible transparent film, for example made of a thermoplastic material such as polycarbonate (PC), polystyrene (PS), polymethyl methacrylate (PMMA), polyethylene (PE) or polypropylene (PP) and mixtures thereof, on which the lenses 11 are formed by molding or printing.

The lenses 11 may also be formed by molding in a first substrate, or deposited by printing onto a first substrate, and the printing of the individual patterns may be carried out on a second substrate made of a material different from the first, this second substrate being assembled with the first, for example using an adhesive, by cold or hot lamination.

The article 1 may also comprise, as seen in particular in figure 3, a layer 15 of a pressure-sensitive adhesive, which makes it possible to attach the article to the human keratin materials. As a variant, the adhesive is applied to the human keratin materials, when the article is brought into contact therewith. This layer of adhesive may be protected, before the first use, by a removable protective film.

The assembly 13 of individual patterns comprises individual patterns that are, for example, in the form of lines if the lenticular array comprises cylindrical lenses.

In the example from figure 4, five images Ii to I ₅ have been represented which may be observed successively when the viewing direction changes, on moving about a reference axis. For example, under normal observation, the image I3 is seen, and on moving toward the left the images and Ii are seen successively, and on moving toward the right the image I ₄ then the image I ₅ are seen. The various images Ii to I ₅ correspond for example to flat color tints, the color of the image I ₃ being, for example, the lightest and the color gradually getting darker toward the extreme images Ii and I ₅ .

The assembly 13 comprises a repetition of sub-assemblies 13' each formed of five successive individual patterns 13 ₁ to 13 ₅ , the color of which corresponds to those of the respective images Ii to I ₅ . Thus, the color of the pattern 13 ₁ corresponds to that of the image Ii, etc.

Each sub-assembly 13' may be associated with one and the same cylindrical lens 11, the generatrix of which is oriented parallel to the reference axis about which the observer must turn in order to successively see all the images appear. Thus, the width of a sub-assembly 13' of individual patterns may correspond to that of the associated lens 1 1 , measured at its base.

When the observer observes the optical structure 10 under normal incidence, all the lenses 11 give the image of the individual pattern 13 ₃ of the sub-assembly 13' which is associated with them. When the incidence changes, it is the other individual patterns that become visible.

In the example from figure 4, all the sub-assemblies 13' of individual patterns are identical. This may not be the case.

By way of example, the possibility for the sub-assemblies 13' of individual patterns to be different depending on the location on the article has been illustrated in figure 5.

For example, it may be sought to produce, using the optical structure 10, images that are not uniform, for example a gradation, the appearance of which changes as a function of the viewing direction.

In this case, the various individual patterns 13i, 13 ₅ of a sub-assembly 13' associated with a given lens 11 are different from those associated with another lens, as illustrated by the sub-assemblies corresponding to the details A and B from figure 5.

Generally, the shape and the placement of the individual patterns depends on the optical structure 10 used.

When the lenses are non-cylindrical, for example spherical, the individual patterns may be arranged as represented in figure 6, with an offset between one another, in accordance with the teaching of application WO 98/20392. More particularly, the shape of the individual pattern may not correspond to the projection of the lens in the plane where the individual pattern lies but have a smaller width and a greater length, so that one and the same individual pattern may lie opposite a portion of the adjacent lens. This may make it possible to gain resolution in one direction.

Such an arrangement of the individual patterns is especially suitable for hexagonal-based lenses, as illustrated in figure 12 of application WO 98/20392, the placement of the individual patterns relative to the lenses being, for example, such as illustrated in figures 15 and 16 of this application WO 98/20392, for hexagonal-based lenses with contiguous sides between two adjacent lenses. These figures are incorporated by reference into the present application.

In the manner of what was described with reference to figure 5, the subassemblies 13' of individual patterns located at various locations of the article may be composed of different individual patterns, as illustrated in figure 7 for the sub-assemblies corresponding to the details A and B.

Yet other arrangements of individual patterns are possible, and it is especially possible to use arrangements proposed in the field of security papers. US 5 712 731 discloses an optical structure formed of a two-dimensional array of lenses. It is possible to use in the invention, as in this prior patent, lenses having a diameter that lies, for example, within the range 20-250 μιη with a focal distance of, for example, approximately 200 μιη.

Patent US 8 009 360 describes other arrangements of lenses, especially with reference to figures 3 a to 3i,. In particular, it emerges from this document that the use of hexagonal-based lenses is particularly advantageous.

In order to manufacture lenses, various techniques have already been proposed in other fields of application in which arrays of lenses have already been used.

The publication WO 2009/147353 discloses a technique for printing via successive passes that can be used in the context of the present invention.

US 4 417 784 discloses a manufacturing technique by embossing a sheet of thermoplastic material, which may also be used.

US 5 712 731 teaches a process that may also be suitable, consisting in coating a substrate with a photosensitive composition, in illuminating the latter with a, for example, hexagonal grid, in developing it so as to leave islands of composition that are separated from one another. Next, the composition is melted and the surface tension of the composition leads to the formation of islands of spherical surface corresponding to the shape of the lenses.

Illustrated in figure 8 is the possibility for the lenses 11 to be aspherical, which may reduce the thickness of the article and make it more comfortable to wear.

Represented in figure 11 is an article 1 intended to be applied to the eyelid. This article may thus have a shape with a curved edge 70 that is concave toward the outside.

The pattern which appears on the various images Ii to I ₅ , the appearance of which changes as a function of the viewing angle, comprises for example an eyelid makeup line M, adjacent to the edge 70. This line becomes, for example, thicker for images I ₂ and I ₄ corresponding to observations under an intermediate angle between normal incidence, which corresponds to image I ₃ , and the extreme incidences, which correspond to images Ii and 15 in figure 12. It is thus possible to obtain a particularly attractive "chiaroscuro" effect.

Represented in figure 14 is an article 1 intended to be applied to the lips, preferably the upper and lower lips. It is possible to vary the brightness of the lips as a function of the viewing angle by producing the individual patterns in the form of flat tints of various colours; it is possible, for example, to choose the individual patterns so that the color observed becomes darker the further away from normal incidence.

Where appropriate, the various images may comprise points M or other patterns, which appear on certain images and disappear on others, making it possible to create a moire effect. These points or other patterns, for example lines, are for example printed on a colored background, which may be a flat color tint.

The optical structure 10 may be other than refractive.

For example, it is possible to use a raster 20 as a replacement for an array of lenses, as illustrated in figure 9. This raster 20 is, for example, formed of lines regularly spaced apart by a distance d, which are placed on top of individual patterns 13i, 13 ₂ , ... 13„.

The raster 20 may be produced by printing or metallization of a support 21, which constitutes an optical spacer, the individual patterns 13i, 13 _n for example being produced by printing on the other face of this support 21. Represented in figure 10 is another example of an optical structure 10, comprising an array of mirrors 30 that reflect an image of the individual patterns of the various rows 13i, ... 13 _n as a function of the viewing direction.

The various individual patterns are, for example, located in the focal plane of the mirrors, which may be concave as illustrated. The mirrors 30 may be formed by metallization of a transparent substrate. Patent US 8 009 360 describes, with reference to figure 1 lb, a similar optical structure 10.

The invention is not limited to the examples that have just been described.

Thus, variants of the invention may comprise a number of individual patterns different from that of the examples illustrated, in particular greater than 5 per subassembly.

The lenses may have other shapes, in particular polygonal-based other than hexagonal-based.

Colorants or luminescent compounds may be added to the article. The individual patterns 131 , 13 _n represented in the figures correspond to various images when the observer moves about a reference axis. It is possible to produce the individual patterns so as to observe a change on moving about two reference axes that are perpendicular to one another. In this case, the individual patterns may be positioned in two rows i and j within each sub-assembly which is repeated, two images Ii, _j and Ii ₊ i, _j observed successively on moving about the first reference axis corresponding to individual patterns 13i, _j and 13i ₊₁ , _j and two images Ii, _j and Ii, _j+ i observed successively on moving about the second reference axis corresponding to individual patterns 13i _j and 13;, _j+1 .

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