Security element for a security document, security document provided therewith and process for manufacturing same

Abstract

The invention in particular relates to a security element comprising a grating of contiguous or adjacent lines in relief, these lines (2) being oriented in directions of respective axes X and Y, while said relief is oriented in a direction of axis Z, at least one of these lines (2) being defined by two consecutive valleys or two consecutive peaks, from which two opposite flanks stem, at least one opposite flank having, in the Y-Z plane, an average slope varying continuously between two extreme values, the set of slopes of said grating being such that, at any given point, the slope P(x,y) respects P(x,y) = k * P1(x,y) + (1-k) * P2(x,y), in which equation: k is a constant between 0.2 and 0.8; and P1(x,y) and P2(x,y) are the respective local slopes of the flank at the point (x,y) of a first virtual structure (S1) and of a second virtual structure.

Description

[0001] Security element for a secure document, secure document provided with it and method for its manufacture

[0002] GENERAL FIELD OF THE INVENTION

[0003] The present invention relates to a security element for a secure document, to a secure document provided with it, as well as to a method for its manufacture. Preferably, the secure document is a valuable document, in particular a banknote.

[0004] STATE OF THE ART

[0005] In document W02020 / 083938 a security element based on light reflection is described, which comprises a network of at least two contiguous or adjacent lines, at least one of these lines being in relief and having two opposite sides, at least one of which is partly inclined, sides which each originate along one of said longitudinal and opposite edges of said line.

[0006] Figure 1 shows, as a reminder, a security element that complies with the instructions in this document.

[0007] This element is only very partially represented in order to make consultation of the figure easier.

[0008] In the example shown here, element 1 comprises a network R formed of three contiguous lines 2, 2' and 2" which extend alongside each other along the Y axis of the three-dimensional reference system (X,Y,Z).

[0009] Of course, it is possible to provide an element with a much larger number of lines. The length K of the lines (along the X axis) is, in this particular case, identical and can be of the order of a few millimeters to a few centimeters. Only a portion is shown here. Similarly, the width k of each of the lines is identical in this specific case.

[0010] The maximum height of each line, along the Z axis, is referenced h.

[0011] Of course, in an embodiment not shown, lines of different widths k can be provided.

[0012] In the example shown, lines 2 to 2" are straight.

[0013] However, in a variant not illustrated here, the network R may comprise curved, circular lines and more generally any shape, or even a single line, for example in the form of a spiral, so that the network R is formed by the plurality of turns of the spiral. In the example shown and in accordance with this prior document, each of the raised lines 2 to 2" has two opposite inclined sides 20 and 21 which each originate along one of the longitudinal and opposite edges 200 and 210 of the line.

[0014] Here the flanks are inclined upwards, meaning that they extend towards each other to an altitude, along the Z axis, higher than that of the longitudinal edges 200 and 210.

[0015] By the expression "inclined flanks" is meant that at least a portion of at least one of these two flanks is inclined. In other words, this does not exclude the flanks being locally vertical or horizontal. These two flanks 20 and 21 join in a single, uninterrupted junction zone 22 of sinuous shape which extends in the longitudinal direction of the line, these flanks 20 and 21 having no discontinuity or interruption, at least in the longitudinal direction.

[0016] In other words, the peaks of this three-dimensional network, which individually constitute the aforementioned junction zone, present for example a sinusoidal modulation (i.e. a variation), in the (X,Y) plane as represented in figure 1.

[0017] Figure 2 shows in an even more simplified manner a network R conforming to a variant of this previous document.

[0018] Here, only two lines 2 and 2' of length K, width k and maximum height h, are represented and we have refrained from showing the sides which connect the crests and furrows of the network R. We note that the crest lines C do not undergo any modulation in this case, that is to say no variation, so that they are always located at the same altitude, along the Z axis and at the same position along the Y axis. On the other hand, the furrow lines S present a large sinusoidal type modulation in the vertical plane, that is to say along the (X,Z) plane.

[0019] Figure 3 shows schematically, seen from above, a network R formed of a plurality of parallel lines, conforming to the embodiment of Figure 2. The network R is represented here in grayscale, the black shade corresponding to the highest points of the structure, while the white shade corresponds to the lowest points of the structure. Of course, the different gray shades correspond to intermediate altitudes between these highest and lowest points. It should be noted that the dimensions have been deliberately exaggerated for better visualization.

[0020] In Figure 3, we note the presence of a ring-shaped area A in the network R, an area in which the slopes of the network are identical. This makes it possible to generate a ring-shaped pattern that is very easily visually recognizable. Of course, other variations in the amplitude of the ridge and / or furrow lines, i.e. along a plane other than the (X,Z) plane, are possible but have not been shown here.

[0021] Such a security element generally gives satisfaction.

[0022] However, it could be improved in terms of visual rendering.

[0023] Indeed, the present applicant has found that such a structure, when it generates a visual impression of ample movement (the definition of this expression, as well as others, is given in the introduction to the detailed description of the present invention), also gives a blurring effect.

[0024] This is particularly visible in Figure 4, which represents the visual effect produced by a structure formed from a network conforming to the previous figures, which generates an impression of ample movement, this structure being declined five times, depending on whether it is seen at -20°, -10°, 0°, +10° and +20°, the angle 0° corresponding to the situation where the observer's axis of view is perpendicular to the average plane in which the security element carrying this structure is contained.

[0025] The broad movement shown in Figure 4 is an enlargement / shrinkage of diamonds.

[0026] Conversely, when dealing with a structure which generates detailed movements (the definition of this expression, as well as others, is given in the introduction to the detailed description of the present invention), these are perceived as almost static and the observer does not perceive any overall movement.

[0027] This is illustrated in Figure 5 representing an enlargement / shrinkage of diamonds arranged in a checkerboard pattern.

[0028] This problem is particularly highlighted when a detailed pattern is embedded on a geometric background which generates ample movement.

[0029] Thus, in Figure 6A is shown a situation in which a small ermine-shaped pattern PH is embedded in a background AP. In Figure 6B is shown a simulation of the visual effect obtained, it being understood that the small ermine-shaped pattern PH is detailed, while the structure of the background AP generates a broad motion effect according to which four oblong shapes evoking an “O” or a “zero” undergo enlargements / shrinkages, the oblong shapes at the top left and bottom right undergoing for example an enlargement, then disappearing to leave in the same tilting movement the oblong shapes, at the bottom left and top right undergoing a shrinkage. In practice, since the surface occupied by the background AP is large relative to the pattern PH, the broad motion effect is clearly visible, while the details of the pattern PH are difficult to distinguish.

[0030] Conversely, when the area occupied by the GH ermine-shaped pattern is large relative to the AP background (see Figure 7A), the details of the large ermine are clearly visible, while the movement effect of the AP background is more difficult to discern, given that a large part of this background is hidden by the GH pattern (see Figure 7B).

[0031] In a way, the two structures associated with the two visual effects “compete”.

[0032] Document W02018 / 045233 constitutes another prior art of interest.

[0033] The present invention aims to overcome the drawback set out above by proposing in particular a security element with patterns whose respective movement effects, taken independently of one another, could each result from a structure such as that described with reference to figure 1, and are, once associated within the same structure, clearly perceptible, without the visual effect of one contradicting or attenuating the other, or vice versa.

[0034] SUMMARY OF THE INVENTION

[0035] For this purpose, the present invention relates in particular to a security element for a secure document which comprises a network of at least two contiguous or adjacent lines in relief, these lines being generally oriented in longitudinal and transverse directions of respective axes X and Y, while said relief is generally oriented in a direction of axis Z perpendicular to said axes X and Y, at least one of these lines in relief being delimited by two consecutive grooves or two consecutive crests, from which two opposite flanks originate joining in a single and uninterrupted junction zone forming a crest, respectively a groove, at least one of said two opposite flanks having in the plane Y, Z orthogonal to said longitudinal direction X an average slope varying continuously along said longitudinal direction X between two extreme values ​​PenteMin and PenteMax such that PenteMin is strictly less than PenteMax,at least a portion of said relief line being such that the transition from PenteMin to PenteMax occurs over a distance, along said longitudinal direction X, visible to the naked eye, all of the slopes in the plane Y, Z of said network in at least a first zone (Z1), being such that, at any point, the slope in the plane Y, ZP(x,y) verifies,

[0036] P(x,y) = k * P1 (x,y) + (1 -k) * P2(x,y) equation in which: k is a constant between 0.2 and 0.8;

[0037] P1 is a continuous function in the X direction on a surface covering at least half of said first area;

[0038] P1 (x,y) is the local slope in the Y, Z plane of the flank at the point (x,y) of a first virtual structure comprising a first network which generates a first pattern with a dynamic visual effect, said first network consisting of at least two contiguous or adjacent lines in relief, these lines being generally oriented in longitudinal and transverse directions of respective axes X and Y, while said relief is generally oriented in a direction of axis Z perpendicular to said axes X and Y, at least one of these lines in relief being delimited by two consecutive grooves or two consecutive crests, from which two opposite flanks originate joining in a single and uninterrupted junction zone forming a crest, respectively a groove, at least one of said two opposite flanks having, in the Y, Z plane orthogonal to said longitudinal direction X,an average slope which varies continuously along said longitudinal direction X between two extreme values ​​PenteMinl and PenteMaxI such that PenteMinl is strictly less than PenteMaxI, at least a portion of said relief line being such that the transition from PenteMinl to PenteMaxI takes place over a distance D1, along said longitudinal direction X, visible to the naked eye;,

[0039] P2 is a continuous function in the X direction on at least one surface visible to the naked eye, covering said first area;

[0040] P2(x,y) is the local slope in the Y, Z plane of the flank at the point (x,y) of a second virtual structure comprising a second network which generates a second pattern with a dynamic visual effect, said second network comprising a network of at least two contiguous or adjacent lines in relief, these lines being generally oriented in longitudinal and transverse directions of respective axes X and Y, while said relief is generally oriented in a direction of axis Z perpendicular to said axes X and Y, at least one of these lines in relief being delimited by two consecutive grooves or two consecutive crests, from which two opposite flanks originate joining in a single and uninterrupted junction zone forming a crest, respectively a groove, at least one of said two opposite flanks having, in the Y, Z plane orthogonal to said longitudinal direction X,an average slope which varies continuously along said longitudinal direction X between two extreme values ​​PenteMinZ and PenteMaxZ such that PenteMinZ is strictly less than PenteMaxZ, at least a portion of said raised line being such that the transition from PenteMinZ to PenteMaxZ takes place over a distance D2, along said longitudinal direction X, visible to the naked eye and such that D2 is strictly less than D1. The present applicant has found that by implementing the characteristics detailed above, the visual effects of the patterns are clearly visible and identified, without the visual effect of one contradicting or attenuating the other, or vice versa.,

[0041] According to other advantageous and non-limiting characteristics of the invention, taken in isolation or according to a technically compatible combination of at least two of them:

[0042] - distance D1 is at least twice as great as distance D2;

[0043] - the functions P1 and P2 are at least partly derivable according to X and the maximum of the derivative of P1 in absolute value is strictly less than the maximum of the derivative of P2 in absolute value, preferably is at least twice as small;

[0044] - said first structure generates a first pattern with a broad dynamic visual effect, while the second structure generates a second pattern with a detailed dynamic effect;

[0045] - k is between 0.5 and 0.7 and is preferably equal to 0.6;

[0046] - said first and second patterns have different optical effects;

[0047] - said first and second reasons are different;

[0048] - said first pattern has a geometric shape configured to encompass a plurality of sub-patterns, said plurality of sub-patterns constituting in particular said second pattern;

[0049] - said second pattern is formed from a network of sub-patterns each composed of the same geometric shape;

[0050] - said security element comprises at least a second zone comprising a network of at least two contiguous or adjacent lines in relief, these lines being generally oriented in longitudinal and transverse directions of respective axes X and Y, while said relief is generally oriented in a direction of axis Z perpendicular to said axes X and Y, at least one of these lines in relief being delimited by two consecutive grooves or two consecutive crests, from which two opposite flanks originate joining in a single and uninterrupted junction zone forming a crest, respectively a groove, at least one of said two opposite flanks having in the plane Y, Z orthogonal to said longitudinal direction X an average slope P3 varying continuously along said longitudinal direction X between two extreme values ​​PenteMin and PenteMax such that PenteMin is strictly less than PenteMax,at least a first portion of said relief line being such that the transition from PenteMin to PenteMax occurs over a distance, in said longitudinal direction X, visible to the naked eye, all the slopes of said second network being such that at any point (x,y) of said second zone, the slope P(x,y) = P1 (x,y);,

[0051] - the ratio of the surface area of ​​said second zone to the surface area of ​​said first zone is between 1 and 40%;

[0052] - said second zone is present, preferably only, where the slope P1 has the same predetermined value.

[0053] The invention also relates to a secure document characterized by the fact that it comprises at least one security element according to one of the preceding characteristics.

[0054] Advantageously, said security element defined above is integrated or is reported in said security document.

[0055] According to a possible embodiment, this document may be a banknote and is characterized in that it is made of paper, fibrous material, plastic, or a combination of at least two of these materials.

[0056] Finally, a last aspect of the present invention relates to a method for manufacturing a security element for a secure document, which comprises a network of at least two contiguous or adjacent lines in relief, these lines being generally oriented in longitudinal and transverse directions of respective axes X and Y, while said relief is generally oriented in a direction of axis Z perpendicular to said axes X and Y, at least one of these lines in relief being delimited by two consecutive grooves or two consecutive crests, from which two opposite flanks originate joining in a single and uninterrupted junction zone forming a crest, respectively a groove, at least one of said two opposite flanks having in the plane Y,Z orthogonal to said longitudinal direction X an average slope varying continuously along said longitudinal direction X between two extreme values ​​PenteMin and PenteMax such that PenteMin is strictly less than PenteMax, at least a portion of said relief line being such that the transition from PenteMin to PenteMax occurs over a distance, along said longitudinal direction X, visible to the naked eye, all the slopes in the plane Y, Z of said network in at least a first zone, being such that, at any point, the slope P(x,y) in the plane Y, Z verifies,

[0057] P(x,y) = k * P1 (x,y) + (1 -k) * P2(x,y) equation in which: k is a constant between 0.2 and 0.8;

[0058] P1 is a continuous function in the X direction on a surface covering at least half of said first area; P2 is a continuous function in the X direction on at least one surface visible to the naked eye, covering said first area; method which comprises implementing the following preliminary steps:

[0059] - generation of a first virtual structure of local slope P1 (x,y) in the Y, Z plane of the flank at the point (x,y), structure comprising a first network which generates a first pattern with a dynamic visual effect, said first network consisting of at least two contiguous or adjacent lines in relief, these lines being generally oriented in longitudinal and transverse directions of respective axes X and Y, while said relief is generally oriented in a direction of axis Z perpendicular to said axes X and Y, at least one of these lines in relief being delimited by two consecutive furrows or two consecutive crests, from which two opposite flanks originate joining in a single and uninterrupted junction zone forming a crest, respectively a furrow, at least one of said two opposite flanks having, in the Y, Z plane orthogonal to said longitudinal direction X,an average slope which varies continuously along said longitudinal direction X between two extreme values ​​PenteMinl and PenteMaxI such that PenteMinl is strictly less than PenteMaxI, at least a portion of said relief line being such that the transition from PenteMinl to PenteMaxI takes place over a distance D1, along said longitudinal direction X, visible to the naked eye;,

[0060] - generation of a second virtual structure of local slope P2(x,y) in the Y, Z plane of the flank at the point (x,y), structure comprising a second network which generates a second pattern with a dynamic visual effect, said second network comprising a network of at least two contiguous or adjacent lines in relief, these lines being generally oriented in longitudinal and transverse directions of respective axes X and Y, while said relief is generally oriented in a direction of axis Z perpendicular to said axes X and Y, at least one of these lines in relief being delimited by two consecutive furrows or two consecutive crests, from which two opposite flanks originate joining in a single and uninterrupted junction zone forming a crest, respectively a furrow, at least one of said two opposite flanks having, in the Y, Z plane orthogonal to said longitudinal direction X,an average slope which varies continuously along said longitudinal direction X between two extreme values ​​PenteMinZ and PenteMaxZ such that PenteMinZ is strictly less than PenteMaxZ, at least a portion of said relief line being such that the transition from PenteMinZ to PenteMaxZ takes place over a distance D2, along said longitudinal direction X, visible to the naked eye and such that D2 is strictly less than D1;,

[0061] - combination of said first and second virtual structures according to the preceding equation. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Other features and advantages of the invention will become apparent from the following description of preferred embodiments of the invention. This description is made with reference to the appended drawings in which:

[0063] Figure 1 is a schematic, three-dimensional and partial view of a network of lines of a security element according to the prior art;

[0064] Figure 2 is an even more simplified view of an alternative embodiment of the security element of Figure 1;

[0065] Figure 3 is a schematic representation, seen from above, of a network formed of a plurality of parallel lines in accordance with the embodiment of Figure 2;

[0066] Figure 4 is a diagram representing, in the form of a simulation, the visual effect of movement produced by a structure formed from a network conforming to the preceding figures, which generates an impression of ample movement, here an effect of enlarging / shrinking two diamonds, the structure being declined five times, depending on whether it is seen at -20°, -10°, 0°, +10° and +20°, the angle 0° corresponding to the situation where the observer's axis of view is perpendicular to the average plane in which the security element which carries this structure is contained;

[0067] Figure 5 is a diagram similar to that of Figure 4, the structure shown generating a visual effect of movement of detail applied here to a checkerboard of small diamonds;

[0068] Figure 6A is a schematic top and principle view of a small ermine-shaped inlay on a background;

[0069] Figure 6B is a view of a simulation following the structure of Figure 6A, in which the overlay generates detail, while the background generates an impression of movement;

[0070] Figure 7A is a schematic top and principle view of a large ermine-shaped inlay on a background;

[0071] Figure 7B is a view of a simulation following the structure of Figure 7A, in which the overlay generates detail, while the background generates an impression of movement;

[0072] Figure 8 is a three-dimensional view of a simulation of a structure generating ample movement, it being understood that the proportions of this structure have been deliberately exaggerated for ease of reference;

[0073] Figure 9 is a three-dimensional view of a simulation of a structure generating details, it being understood that the proportions of this structure have been deliberately exaggerated to facilitate consultation; Figure 10 is a three-dimensional view of a simulation of a structure obtained in accordance with the invention, from the structures of Figures 8 and 9, it being understood that the proportions of this structure have been deliberately exaggerated to facilitate consultation;

[0074] Figure 11 is a view similar to Figure 10 of an alternative embodiment of a structure obtained in accordance with the invention;

[0075] Figure 12 is a diagram representing, in the form of a simulation, the visual effect of movement applied to a checkerboard of small diamonds and two large diamonds, and produced by a structure formed from a network in accordance with the present invention depending on whether it is seen at -20°, -10°, 0°, +10° and +20°, the angle 0° corresponding to the situation where the observer's viewing axis is perpendicular to the mean plane in which the security element carrying this structure is contained;

[0076] Figure 13 is a diagram similar to that of Figure 12, in which the coefficient k of the equation which will be detailed later in the description has been varied;

[0077] Figure 14 is a diagram of a variant of the embodiment of Figures 12 and 13;

[0078] Figure 15 is a schematic top view of a structure according to a specific feature described in the present application according to which a TL zone (in white) generates only a broad motion effect;

[0079] Figure 16 is analogous to Figure 15 and represents the same structure, with zone Z1 (inverse of zone TL shown in Figure 15) generating a broad movement effect combined with a detail movement effect;

[0080] Figures 17A to 17F are schematic top views of simulations of structures that are described by the value of their slopes (each gray level corresponds to a given slope value) that vary along the X and Y axes, showing respectively a first virtual structure that generates a first pattern with a broad motion effect, described by the set of slopes P1 (x,y) (Figure 17A), a second virtual structure that generates a second pattern with a detailed motion effect, described by the set of slopes P2 (x,y) (Figure 17B), a virtual structure derived from that of Figure 17A, described by the set of slopes P1 '(x,y) = 0.6 * P1 (x,y) (Figure 17C), a virtual structure derived from that of Figure 17B, described by the set of slopes P2' (x,y) = (1 -0.6) * P2 (x,y) (Figure 17D), the real structure resulting from the combination of the two previous virtual structures, described by the set of slopes P(x,y)=P1 '(x,y)+P2'(x,y) (figure 17E) and the real structure resulting from the combination of said two previous virtual structures, comprising an area in which the slopes P(x,y)=P1 (x,y) (figure 17F);,

[0081] Figures 18A to 18F are schematic top views of simulations of structures that are described by the value of their slopes (each gray level corresponds to a given slope value) that vary along the X and Y axes, showing respectively a first virtual structure that generates a first pattern with a broad motion effect, described by the set of slopes P1 (x,y) (Figure 18A), a second virtual structure that generates a second pattern with a detailed motion effect, described by the set of slopes P2 (x,y) (Figure 18B), a virtual structure derived from that of Figure 18A, described by the set of slopes P1 '(x,y) = 0.6 * P1 (x,y) (Figure 18C), a virtual structure derived from that of Figure 18B, described by the set of slopes P2' (x,y) = (1 -0.6) * P2 (x,y) (Figure 18D), the real structure resulting from the combination of the two previous virtual structures, described by the set of slopes P(x,y)=P1 '(x,y)+P2'(x,y) (figure 18E) and the real structure resulting from the combination of the two previous virtual structures, comprising an area in which the slope P(x,y)=P1 (x,y) (figure 18F);,

[0082] Figures 19 to 23 are schematic sectional views of multi-layer security elements in accordance with the invention;

[0083] Figure 24 is a top view of a banknote which incorporates two security elements in accordance with the invention.

[0084] Figures 4, 5, 6B, 7B, 12, 13 and 14 represent the visual effects obtained. Thus, in these figures, the different gray levels correspond to a perceived light intensity ranging from white for a very bright area to black for a very dark area.

[0085] DETAILED DESCRIPTION OF THE INVENTION

[0086] DEFINITIONS AND CLARIFICATIONS

[0087] Throughout this application, including the claims, the terms and expressions detailed below have the following definitions:

[0088] - pattern: light pattern perceived when a light source is reflected by a reflective structure whose slopes vary locally and represent a particular shape.

[0089] - visual impression of movement: this is an impression of displacement (translation and / or rotation) and / or enlargement / shrinkage and / or transformation (passage from form A to form B for example, preferably with return to form A) of a motif.

[0090] - visual impression of broad movement, respectively of detail: applies to an impression of movement of a motif which has a large amplitude, relative to that of a detail motif whose amplitude of movement is less. These effects (of broad and detailed movements) can be grouped under the generic term "dynamic (visual) effects", and are defined as being displacements (translation and / or rotation) and / or transformations and / or enlargements / shrinkages of a motif.

[0091] These dynamic effects are effects visible during a relative movement between, on the one hand, the security element on which the pattern is affixed and, on the other hand, the observer and / or the illumination of the security element.

[0092] They are particularly visible when the security element is tilted relative to the observer (a phenomenon well known under the Anglo-Saxon terms "tilt" and "tilting") or by relative movement between the observer or the illumination on the one hand and the security element on the other.

[0093] Throughout the present application, including the claims, the expression "local slope of a structure" means the slope of the flank, which goes from the crest to the furrow, for a given position (x,y), along the Y axis. Along the two axes X and Y, we therefore obtain a set of slopes P(x,y) which describes the structure considered.

[0094] The following examples describe structures with patterns of the same shape. This is by no means mandatory. Patterns of different shapes may be used, as in the examples in Figures 17 and 18.

[0095] The patterns preferably exhibit different dynamic effects. However, it is possible to consider that these are the same two effects, for example enlargement / shrinkage, but at different scales, as illustrated in Figures 12 to 16.

[0096] In the description and claims which follow, the first and second structures are “virtual” structures, which means that they are not concretely affixed to the security element of the invention, but that they make it possible to obtain the real structure according to the invention.

[0097] EXAMPLES OF ACHIEVEMENT

[0098] FIGURES 8 TO 11

[0099] In these figures, three-dimensional structures are represented, the proportions of which have been deliberately exaggerated in order to make the slope modulations clearly visible. More precisely, in Figure 8, we are dealing with a first structure S1 which generates a broad movement.

[0100] This structure S1 is formed from a network R formed from a plurality of parallel lines 2, conforming to the embodiment of figure 1.

[0101] Unlike the previous 2D figures, the perspective views are represented here with a gradient effect from black to white in the manner of a lighting and shading effect where the light source would come from the left side.

[0102] We note essentially, in the upper left corner of the structure, a region G1 in which the local slope of one of the sides of the structure is such that the "altitude" of the grooves along the Z axis rises as we move along the axis

[0103] X, from front (bottom of figure) to back (top of figure).

[0104] The different lines 2 have an identical pitch in the direction of the axis

[0105] Y.

[0106] In Figure 9 a second structure S2 is shown which generates a detailed movement.

[0107] Like the structure S1, the structure S2 is formed of a network R formed of a plurality of parallel lines 2, in accordance with the embodiment of figure 1.

[0108] The different lines 2 have an identical pitch in the Y-axis direction, which is the same as that of the lines of structure S1. Alternatively, the lines of structures S1 and S2 have different respective pitches.

[0109] This structure is essentially characterized by the fact that it integrates a G2 region in the general shape of a cross in which the local slope of one of the sides of the structure is such that the "altitude" of the grooves along the Z axis rises and falls as one moves along the X axis, from the front (bottom of the figure) to the rear (top of the figure), while also undergoing variations along the Y axis.

[0110] We denote by P1 and P2 the sets of respective slopes of structures S1 and S2.

[0111] These two structures are virtual structures, for example calculated or created by computer, which are not strictly speaking found on the security element according to the invention.

[0112] However, as mentioned above, the present applicant has found that from such virtual structures, if at least one zone Z1 of structure SR of the same general type as those described above is implemented on a security element and the set of slopes P of which is given by the relation:

[0113] P = k * P1 + (1 - k) * P2 equation in which: k is a constant between 0.2 and 0.8;

[0114] P1 is the set of slopes of the first structure S1;

[0115] P2 is the set of slopes of the second structure S2, then the visual effects of the patterns of the two structures are clearly visible and identified, without the visual effect of one contradicting or attenuating the other, or vice versa.

[0116] Thus, in Figure 10 is represented the real structure SR which results from the structures S1 and S2 of the two previous figures and whose set of slopes P is equal to 0.6 * P1 + ((1 - 0.6) * P2).

[0117] However, in order to further improve the perception of the effect of broad motion without attenuating that of the details (i.e. without increasing k too much), it is possible to provide, as illustrated by figure 11, at least one TL zone of SR' structure in which the set of slopes is that linked to broad motion without transformation.

[0118] In this case, this means that in this second zone Z2, all the slopes are equal to P1.

[0119] FIGURE 12

[0120] This figure shows simulations of the visual effect produced by a particular example of SR structure whose set of slopes P = k * P1 + (1 - k) * P2.

[0121] This SR structure results from the initial virtual structures whose simulations of their visual effects are represented respectively in figures 4 and 5.

[0122] In Figure 12, the coefficient k is equal to 0.6.

[0123] From left to right in this figure, the overall visual effect produced by an SR structure is represented, this structure being declined five times, depending on whether it is seen at -20°, -10°, 0°, +10° and +20°, the angle 0° corresponding to the situation where the observer's viewing axis is perpendicular to the average plane in which the security element which carries this structure is contained.

[0124] Thus, for an inclination ranging from -20° to +20°, we can clearly see the two large diamonds which grow outwards (large movement). However, at each stage of inclination, we can also see the small diamonds which give detail to the movement.

[0125] In this example, the first pattern (consisting of large diamonds) has a geometric shape configured to encompass a second pattern consisting of a network of sub-patterns each composed of the same geometric shape (in this case small diamonds). This allows for very remarkable visual effects to be obtained in the sense that the correspondence of the geometric shapes and their sequential illumination by scanning according to the inclination generates a particularly harmonious overall effect and an intuitive overall understanding for the observer.

[0126] Of course, this is only an example and it is quite possible that the first and second motifs have nothing in common geometrically.

[0127] FIGURE 13

[0128] This figure shows simulations of the visual effect produced by the same SR structure as that of figure 12, except that the coefficient k is varied, which is respectively, from left to right, 0.2, 0.4, 0.6 and 0.8.

[0129] Even if for the value k=0.2, the details are clearly perceived while the broad movement in the form of large diamonds is more difficult to grasp and, conversely, for the value k=0.8, the broad movement in the form of large diamonds is correctly perceived, while the detailed movements are more difficult to grasp, the results are generally satisfactory for the values ​​between 0.2 and 0.8.

[0130] On the other hand, for values ​​of k less than 0.2, we no longer perceive the effect of ample movement, and for values ​​of k greater than 0.8, it is the details which tend to disappear. Thus, we fall back into the case where there is only one effect because the weighting relationship favors one to the detriment of the other.

[0131] In any case, as long as k is between 0.5 and 0.7 and preferably equal to 0.6, the results obtained are particularly satisfactory.

[0132] FIGURES 14 to 16

[0133] Figure 14 shows simulations of the visual effect produced by the same SR structure as in Figure 13. However, in order to further improve the perception of the effect of broad motion without attenuating that of the details, a TL zone has been provided in which the slopes are those related to broad motion without transformation, which means that the set of slopes in the TL zone is equal to P1.

[0134] In practice, this allows us to continue to clearly discern the large diamonds that constitute the broad movement, even for a low value of k. Visualized differently and as shown in figures 15 and 16, in zone Z2, the set of slopes is equal to P1, while in zone Z1, the set of slopes is equal to P.

[0135] Preferably and so that the patterns “do not compete”, it will be preferred that the ratio of the surface area of ​​the second zone TL to the surface area of ​​the first zone Z1 be between 1 and 40%.

[0136] FIGURES 17A to 17F

[0137] In Figure 17A a first structure S1 with ample movement is shown. Its set of slopes is P1.

[0138] In Figure 17B a second structure S2 with detailed movement is shown, which is characterized by a combination of diamonds of different dimensions and arranged alternately. Its set of slopes is P2.

[0139] Figure 17C shows the first structure of Figure 17A, but assigning the coefficient k = 0.6 to the slope P1.

[0140] Figure 17D shows the second structure of Figure 17B, but assigning the coefficient k = (1-0.6) to the slope P2.

[0141] Figure 17E shows the structure SR which results from the combination of structures S1 and S2 and whose set of slopes P is governed by the relation

[0142] P = k * P1 + (1 - k) * P2 where k= 0.6.

[0143] The patterns are clearly sharp and the resulting dynamic visual effects are clearly visible.

[0144] Figure 17F is similar to Figure 17E, except that there is a region TL in which all slopes are equal to P1 .

[0145] FIGURES 18A to 18F

[0146] In Figure 18A a first structure S1 with ample movement is shown. Its set of slopes is P1.

[0147] In Figure 18B is shown a second structure S2 with detailed movement which is characterized by a general rosette shape, consisting of three groups of segments in the form of particular quadrilaterals, that is to say comprising two curved sides and two rectilinear sides, the curved sides being inscribed in the concentric circles constituting the rosette, as well as a group of segments in the general form of triangles. Its set of slopes is P2.

[0148] Figure 18C shows the first structure of Figure 18A, but assigning the coefficient k = 0.6 to the slope P1.

[0149] Figure 18D shows the second structure of Figure 18B, but assigning the coefficient k = (1-0.6) to the slope P2.

[0150] Figure 18E shows the structure SR which results from the combination of structures S1 and S2 and whose set of slopes P is governed by the relation

[0151] P = k * P1 + (1 - k) * P2 where k = 0.6

[0152] The patterns are clearly sharp and the resulting dynamic visual effects are clearly visible.

[0153] Figure 18F is similar to Figure 18E, except that there is a region TL in which all slopes are equal to P1 .

[0154] Through the last examples of figures 17 and 18 as well as on other designs, the applicant was able to verify on digital simulations but also on real structures according to the invention, produced from said simulations, the desired captivating effect, that is to say the simultaneous generation of a clearly identifiable overall movement and highly visible detailed movements, in connection with the overall movement, thus enriching the overall iconography of the security element and its perception.

[0155] PROCESS FOR MANUFACTURING THE SECURITY ELEMENT

[0156] The method for manufacturing the security element according to the invention is well known to those skilled in the art: once the digital simulations have given complete satisfaction in terms of their visual rendering, a digital image in the form of a file used for origination is generated. The digital origination then results in a real origination in a medium capable of faithfully representing in three dimensions the desired image and the expected effects. Thus, and without this being limiting, the engravings of the microstructures are made according to the gray levels of the two-dimensional images obtained. Each gray level corresponds to an engraving depth. A matrix is ​​then formed with within it the faithful imprint of the desired microstructure.

[0157] Other processes, also well known to those skilled in the art, allowing the manufacture of production tools (embossing tools in particular) from this matrix are then implemented. Such processes include, for example, the following steps: replication, recombination, electroplating, etc. SECURE DOCUMENT COMPRISING A SECURITY ELEMENT

[0158] The security element according to the invention can be applied or integrated within a secure document such as a banknote or a passport.

[0159] It can take various forms such as a “patch”, a stripe or “foil” or a security thread, the latter being particularly intended to be integrated into windows.

[0160] Finally, it can also be directly built on a support made of any material:

[0161] - natural (such as cellulose), in particular recycled or bio-sourced, or

[0162] - artificial, in particular fossil (BOPP, PET etc.), recycled or bio-sourced, for example from a resin deposited on said support and which would receive an imprint according to the invention by embossing (for example by “UV casting” or by another process).

[0163] In many situations, the security element is multi-layered and examples of this are given in figures 19 to 23. For the purposes of good understanding, it should be noted that in these figures the assembly E is seen in section, and that the layers are represented schematically, in particular without the proportions concerning their thicknesses being respected and without their possible surface reliefs being represented.

[0164] Thus, according to the embodiment of Figure 19, we are dealing with an assembly E which has a security structure 1 according to the invention consisting of a plastic film 3 covered by an embossable varnish 4. For the sake of clarity, it should be understood that the layer 4 is embossed or shaped according to the structure 1. On this structure 1 are successively deposited thin layers of chromium 5, silica oxide 6 and aluminum 7, and this for illustration purposes only. These last three layers compose for certain given thicknesses an interference filter capable of generating a change in color when the angle of observation and / or illumination changes. The perceived colors can be calculated and depend on the thicknesses of the thin layers 5, 6 and 7.

[0165] Of course, other stacks of thin layers with other materials and / or a different number of layers can be envisaged to produce remarkable visual effects. A portion of the aluminum 7 is then locally removed to create openings 70.

[0166] According to this variant, the observer who looks at this assembly from the side of the film 3 will notice the combination of several optical effects. Thus, the layers 5, 6 and 7 cause color change effects of the structure depending on its angle of observation and / or illumination, for example from magenta to green. This color change effect depends both on the macroscopic angle of inclination of the assembly E relative to an observer and is combined with the effect of the dynamic reflection structure according to the invention which depends on the local angle of inclination of the slopes of the microstructures. This combination makes it possible to obtain remarkable visual effects rich in nuances.

[0167] In the embodiment of Figure 20, we are dealing successively, from top to bottom, with a plastic film 3, an embossable varnish 4, an aluminum layer 7 having openings 70, a silicon oxide layer 6 and a chromium layer 5. On this set of superimposed layers is made the security element 1. Although this is not shown in Figure 1, the interfaces of the layers 5, 6, 7 and 4 follow the relief of the structure 1.

[0168] Yet another set E is shown in Figure 21, the observation side being that of the thin layer of chromium 5.

[0169] In the embodiment of Figure 22, there is a support 3 which has within it or on its surface a color change effect. This comprises a multilayer material with a variation in refractive index or at least one liquid crystal ink. This support is coated with the security structure 1 which is in this case a varnish deformed during its application by micro-replication in the wet state (for example by "UV casting" already mentioned above or "Nano Imprint" in English) assisted by concomitant drying with ultraviolet radiation, so that the shape of the engraved tool reproduces its imprint in the varnish and the varnish then retains, in negative, the reliefs of the engraved tool. The varnish is then covered with a colored layer 7, for example black, so as to reveal, when observed through the support and directly above the printed areas 71, a combined effect of color change and dynamic reflection according to the invention.In the openings 70 corresponding to areas not coated with black ink, a clear and transparent text effect is achieved.

[0170] In the embodiment of figure 23, the varnish support 3 is interposed between the security element 1 and the layer 7. In addition, behind the element 1, an additional layer 6 is provided whose refractive index is sufficiently different from that of the varnish of the varnish support 3. This layer is preferably chosen from varnishes with a high refractive index, for example of the ZnS type, or with a low refractive index, of the perfluoropolyether type.

[0171] Of course, additional layers used for the manufacture of security elements such as threads, such as camouflage layers, layers for complexing with another plastic support or thermoadhesives, protection, adhesive, have not been shown in the figures which have just been described, for the purposes of simplification. As shown in Figure 24, we are dealing with a banknote 8 which has two security elements in accordance with the invention, namely on the left part a security element 1 which has the shape of a rectangular block (a "patch"), and on its right an element 1 in the form of a security thread in windows.

Claims

CLAIMS 1. Security element (1) for a secure document which comprises a network (R) of at least two contiguous or adjacent raised lines (2, 2'), these lines (2, 2') being generally oriented in longitudinal and transverse directions of respective axes X and Y, while said relief is generally oriented in a direction of axis Z perpendicular to said axes X and Y, at least one of these raised lines (2, 2') being delimited by two consecutive grooves (S) or two consecutive crests (C), from which two opposite flanks originate joining in a single and uninterrupted junction zone forming a crest (C), respectively a groove (S), at least one of said two opposite flanks having in the plane Y, Z orthogonal to said longitudinal direction X an average slope varying continuously along said longitudinal direction X between two extreme values ​​PenteMin and PenteMax such that PenteMin is strictly less than PenteMax,at least a portion of said line (2, 2') in relief being such that the transition from PenteMin to PenteMax occurs over a distance, in said longitudinal direction X, visible to the naked eye, all of the slopes in the plane Y, Z of said network in at least a first zone (Z1), being such that, at any point, the slope P(x,y) in the plane Y, Z verifies, P(x,y) = k * P1 (x,y) + (1 -k) * P2(x,y) equation in which: k is a constant between 0.2 and 0.8; P1 is a continuous function in the X direction on a surface covering at least half of said first zone (Z1); P1 (x,y) is the local slope in the Y, Z plane of the flank at the point (x,y) of a first virtual structure (S1) comprising a first network which generates a first pattern with a dynamic visual effect, said first network (R1) consisting of at least two contiguous or adjacent lines in relief (2, 2'), these lines (2, 2') being generally oriented in longitudinal and transverse directions of respective axes X and Y, while said relief is generally oriented in a direction of axis Z perpendicular to said axes X and Y, at least one of these lines (2, 2') in relief being delimited by two consecutive grooves (S) or two consecutive ridges (C), from which two opposite flanks originate joining in a single and uninterrupted junction zone forming a ridge (C), respectively a groove (S), at least one of said two opposite flanks having, in the Y, Z plane orthogonal to said longitudinal direction X,an average slope which varies continuously along said longitudinal direction X between two extreme values ​​SlopeMin! and SlopeMax! such that, PenteMinl is strictly less than PenteMaxI, at least a portion of said line (2, 2') in relief being such that the passage from PenteMinl to PenteMaxI takes place over a distance D1, in said longitudinal direction X, visible to the naked eye; P2 is a continuous function in the X direction on at least one surface visible to the naked eye, covering said first zone Z1; P2(x,y) is the local slope in the Y, Z plane of the flank at the point (x,y) of a second virtual structure (S2) comprising a second network which generates a second pattern with a dynamic visual effect, said second network comprising a network (R2) of at least two contiguous or adjacent lines in relief (2, 2'), these lines (2, 2') being generally oriented in longitudinal and transverse directions of respective axes X and Y, while said relief is generally oriented in a direction of axis Z perpendicular to said axes X and Y, at least one of these lines (2, 2') in relief being delimited by two consecutive grooves (S) or two consecutive ridges (C), from which two opposite flanks originate joining in a single and uninterrupted junction zone forming a ridge (C), respectively a groove (S), at least one of said two opposite flanks having, in the Y, Z plane orthogonal to said longitudinal direction X,an average slope which varies continuously along said longitudinal direction X between two extreme values ​​PenteMinZ and PenteMaxZ such that PenteMinZ is strictly less than PenteMaxZ, at least a portion of said line (2, 2') in relief being such that the passage from PenteMinZ to PenteMaxZ takes place over a distance D2, along said longitudinal direction X, visible to the naked eye and such that D2 is strictly less than D1., 2. Safety element (1) according to claim 1, characterized in that said distance D1 is at least twice as great as said distance D2.

3. Security element (1) according to claim 2, characterized in that said functions P1 and P2 are at least partly derivable according to X and that the maximum of the derivative of P1 in absolute value is strictly less than the maximum of the derivative of P2 in absolute value, preferably is at least twice as small.

4. Security element (1) according to one of claims 1 to 3, characterized in that said first structure (S1) generates a first pattern with a broad dynamic visual effect, while the second structure (S2) generates a second pattern with a detailed dynamic effect.

5. Security element (1) according to claim 4, characterized in that k is between 0.5 and 0.7 and is preferably equal to 0.

6.

6. Security element (1) according to one of claims 1 to 5, characterized in that said first and second patterns have different optical effects.

7. Security element (1) according to one of claims 1 to 6, characterized in that said first and second patterns are different.

8. Security element (1) according to at least one of claims 1 to 7, characterized in that said first pattern has a geometric shape configured to encompass a plurality of sub-patterns, said plurality of sub-patterns constituting in particular said second pattern.

9. Security element (1) according to at least one of claims 1 to 8, characterized in that said second pattern is formed from a network of sub-patterns each composed of the same geometric shape.

10. Security element (1) according to at least one of the preceding claims, characterized in that it comprises at least one second zone (Z2) comprising a second network of at least two contiguous or adjacent lines in relief (2, 2'), these lines (2, 2') being generally oriented in longitudinal and transverse directions of respective axes X and Y, while said relief is generally oriented in a direction of axis Z perpendicular to said axes X and Y, at least one of these lines (2, 2') in relief being delimited by two consecutive grooves (S) or two consecutive crests (C), from which two opposite flanks originate joining in a single and uninterrupted junction zone forming a crest (C), respectively a groove (S), at least one of said two opposite flanks having in the plane Y,Z orthogonal to said longitudinal direction X an average slope P3 varying continuously along said longitudinal direction X between two extreme values ​​PenteMin and PenteMax such that PenteMin is strictly less than PenteMax, at least a first portion (PR1) of said line (2, 2') in relief being such that the passage from PenteMin to PenteMax takes place over a distance, along said longitudinal direction X, visible to the naked eye, all of the slopes of said, second network being such that, at any point (x,y) of said second zone, the slope P(x,y) = P1 (x,y).

11. Security element (1) according to claim 10, characterized in that the ratio of the surface area of ​​the second zone (Z2) to the surface area of ​​the first zone (Z1) is between 1 and 40%.

12. Safety element (1) according to claim 10 or 11, characterized in that said second zone (Z2) is present, preferably only, where the slope P1 has the same predetermined value.

13. Secure document (8), characterized in that it comprises at least one security element (1) according to one of the preceding claims.

14. Secure document (8) according to claim 13, characterized in that said security element (1) is integrated therein or is attached thereto.

15. Secure document (8), in particular a banknote, according to claim 13 or claim 14, characterized in that it is made of paper, fibrous material, plastic, or a combination of at least two of these materials.

16. Method for manufacturing a security element (1) for a secure document, which comprises a network (R) of at least two contiguous or adjacent raised lines (2, 2'), these lines (2, 2') being generally oriented in longitudinal and transverse directions of respective axes X and Y, while said relief is generally oriented in a direction of axis Z perpendicular to said axes X and Y, at least one of these raised lines (2, 2') being delimited by two consecutive grooves (S) or two consecutive crests (C), from which two opposite flanks originate joining in a single and uninterrupted junction zone forming a crest (C), respectively a groove (S), at least one of said two opposite flanks having in the plane Y, Z orthogonal to said longitudinal direction X an average slope varying continuously along said longitudinal direction X between two extreme values ​​PenteMin and PenteMax such that PenteMin is strictly less than to PenteMax,at least a portion of said line (2, 2') in relief being such that the transition from PenteMin to PenteMax takes place over a distance, in said longitudinal direction X, visible to the naked eye, all the slopes in the plane Y, Z of said, network in at least a first zone (Z1), being such that, at any point, the slope P(x,y) in the plane Y, Z verifies P(x,y) = k * P1 (x,y) + (1 -k) * P2(x,y) equation in which: k is a constant between 0.2 and 0.8; P1 is a continuous function in the X direction on a surface covering at least half of said first zone (Z1); P2 is a continuous function in the X direction on at least one surface visible to the naked eye, covering said first zone (Z1); method which comprises implementing the following preliminary steps: - generation of a first virtual structure (S1) of local slope P1 (x,y) in the Y, Z plane of the flank at the point (x,y), structure comprising a first network which generates a first pattern with a dynamic visual effect, said first network (R1) consisting of at least two contiguous or adjacent lines in relief (2, 2'), these lines (2, 2') being generally oriented in longitudinal and transverse directions of respective axes X and Y, while said relief is generally oriented in a direction of axis Z perpendicular to said axes X and Y, at least one of these lines (2, 2') in relief being delimited by two consecutive furrows (S) or two consecutive crests (C), from which two opposite flanks originate, joining in a single and uninterrupted junction zone forming a crest (C), respectively a furrow (S), at least one of said two opposite flanks having, in the Y, Z plane orthogonal to said longitudinal direction X,an average slope which varies continuously along said longitudinal direction X between two extreme values ​​PenteMinl and PenteMaxI such that PenteMinl is strictly less than PenteMaxI, at least a portion of said line (2, 2') in relief being such that the passage from PenteMinl to PenteMaxI takes place over a distance D1, along said longitudinal direction X, visible to the naked eye;, - generation of a second virtual structure (S2) of local slope P2(x,y) in the Y, Z plane of the flank at the point (x,y), structure comprising a second network which generates a second pattern with a dynamic visual effect, said second network comprising a network (R2) of at least two contiguous or adjacent lines in relief (2, 2'), these lines (2, 2') being generally oriented in longitudinal and transverse directions of respective axes X and Y, while said relief is generally oriented in a direction of axis Z perpendicular to said axes X and Y, at least one of these lines (2, 2') in relief being delimited by two consecutive furrows (S) or two consecutive crests (C), from which two opposite flanks originate, joining in a single and uninterrupted junction zone forming a crest (C), respectively a furrow (S), at least one of said two opposite flanks having, in the plane Y, Z orthogonal to said longitudinal direction X, an average slope which varies continuously along said longitudinal direction X between two extreme values ​​PenteMinZ and PenteMaxZ such that PenteMinZ is strictly less than PenteMaxZ, at least a portion of said line (2, 2') in relief being such that the passage from PenteMin2 to PenteMax2 takes place over a distance D2, along said longitudinal direction X, visible to the naked eye and such that D2 is strictly less than D1; - combination of said first and second virtual structures (S1, S2) according to the preceding equation.

Images