FR3130194A1 - Security element for a secure document and secure document provided with it - Google Patents

Abstract

The present invention relates in particular to a security element for a secure document which consists of a support, comprising a network of parallel lines (2) in relief, in particular oriented in a preferred direction X, each of which has a width L, each line in relief (2) comprising a profile having at least one crest (21) and one furrow (20), said network being at least partly colored and consisting of a repetition of contiguous or adjacent strips (3), strips ( 3) of width L', each formed of N threads (30-32), N being an integer greater than or equal to two, contiguous or adjacent with, where appropriate, a space between threads having a width smaller than the width of a thread, these N threads (30-32) being of at least two different colors, the said strips (3) extending substantially parallel to the lines in relief (2) of the said network, characterized in that, in at least one region of said colored network, the lines (30-32) of at least one band (3) propagate from one end to the other of this region according to a continuous function F(x), partly differentiable and whose derivative is not constant and there is, within said region, an interval of length Li visible to the naked eye in which the derivative of said function F(x) is between L/(2Li) and 3L/Li, or between -3L/Li and –L/(2Li). Picture 11

Description

Security element for a secure document and secure document provided with it

GENERAL FIELD OF INVENTION

The present invention relates to a security element for a secure document as well as to a secure document provided with it. Preferably, the latter is a valuable document, in particular a banknote.

STATE OF THE ART

The document EP2691573 describes a security element for a valuable document which consists of an initially flat support, comprising a network of lines in relief, each line in relief comprising a profile, said profile comprising variations of gradual shape along along a determined line or from one line to another, this network being colored.

According to this invention, the colored network consists of a repetition of contiguous bands, formed of adjacent or contiguous lines of at least two different colors, these bands generally presenting the same direction as said lines of said network.

In this document, it is mainly the lines in relief (embossed, for example by the technique of intaglio) which present a modulation (that is to say a variation) along the lines. In practice, this allows only limited color variation along the lines.

Thus, when the security element, consisting of three colors, is carried by a banknote and the latter is tilted, we generally only see one, or at best two dominant color(s) distributed (s) in the form of generally vertical bands. Suppose that the dominant color perceived on a ticket given at the level of this security element is red and the minor color is blue. If on the next banknote, supposed to be identical to the previous one, there is a gap between the reliefs generated by the intaglio and the colored lines (red and blue) printed for example by the offset technique, it may be that the 'we see another dominant color, for example blue, red being perceived as a minor color.

We will then have the impression that, from one note to another, the effect is different. This can be disturbing especially since the tickets must, in principle, all be substantially identical.

As previously described, there is no connection between the modulation of the relief provided by the intaglio and the pattern or the image in which the security is contained. Since the perceived effect is mainly confined to parallel lines of different colors, there is no intuitive dimension to the authentication of the security element in question.

In addition, we are often forced to tilt the note very strongly to see the effect appear.

The aim of the present invention is to at least partially solve the first problem detailed above, so that, even if there is in practice a discrepancy (lack of identification between the reliefs, embossed for example by a dry stamp size smooth, and the colored stripes, printed for example by the offset technique) from one note to another, the visual impression which results from the combination of the reliefs with the colored stripes is similar, even identical and/or comforts the observer with an enhanced visual experience, in particular thanks to a more attractive burst of colors, and therefore facilitating the act of authentication.

Thus, a first object of the invention relates to a security element for a secure document which consists of a support, comprising a network of parallel lines in relief, in particular oriented in a preferred direction X, each of which has a width L, each line in relief comprising a profile having at least one crest and one furrow, said network being at least partly colored and consisting of a repetition of contiguous or adjacent bands, bands of width L' each formed of N threads, N being an integer greater than or equal to two, contiguous or adjacent with, where applicable, a space between threads having a width smaller than the width of a thread, these N threads being of at least two different colors, said bands s extending substantially parallel to the lines in relief of the said network, characterized in that, in at least one region of the said colored network, the threads of at least one band propagate from one end to the other of this region according to a function continuous F(x), partly differentiable and whose derivative is not constant, and that there exists, within said region, an interval of length Li visible to the naked eye in which the derivative of said function F(x ) is between L/(2Li) and 3L/Li, or between -3L/Li and -L/(2Li).

Expressed otherwise, in at least one region of said colored network, the threads of at least one band propagate from one end to the other of this region in a nonlinear manner, for example by undergoing an inflection, in other words by having a sinuous aspect, and/or comprising one or more angular point(s), and/or describing a curve, and there is, within said region, an interval of length Li visible to the naked eye in which the derivative of said function F(x) is between L/(2Li) and 3L/Li, or between -3L/Li and -L/(2Li).

Thanks to these characteristics and due to the introduction of a modulation in the lines of the colored network, we are dealing with a "dispersion" of the colors of the lines within the security element, so that all these colors are visible at the same time, even if there is a small registration defect between the lines in relief and these threads. Under these conditions, two different banknotes seem to have identical security elements and/or the visual experience of the observer is enriched during the act of authentication.

According to other advantageous and non-limiting characteristics of this security element, taken alone or according to a technically compatible combination of at least two of them:

- N is equal to 3;

- Said parallel lines in relief are oriented in a preferred direction X;

- said bands extend parallel to the lines in relief;

- said width L of the lines in relief is constant within said network in relief, preferably between 10 micrometers and 2 millimeters, preferably between 30 micrometers and 1 millimeter, more preferably between 300 and 500 micrometers;

- the width L′ of said bands is constant within said colored network;

- L is substantially equal to L', in particular equal to L' ± 5%, preferably equal to L';

- the depth of the raised lines is less than 200 micrometers, preferably between 50 and 150 micrometers, more preferably between 50 and 80 micrometers;

- said space between said threads has a width at least twice as small as the width of a thread;

- said space between said nets has a width of approximately 30 micrometers;

- Li is greater than 1 millimeter, preferably greater than 2 millimeters and even more preferably greater than 3 millimeters;

- Said profile has variations in gradual shape along a determined line of direction X which result in particular in a gradual variation in the position of the crest or of the furrow of this profile in the plane orthogonal to the direction X;

- Said profile has gradual variations in shape from one line to another which result in particular in a gradual variation in the position of the crest or of the furrow of this profile in the plane orthogonal to the direction X;

- within said at least one region of said colored network, said gradual variation of the position of the crest or of the furrow of said profile describes a function kF, k being a non-zero constant;

- the constant k is greater than or equal to -1 and strictly less than zero;

- said at least one region of said colored network is included in an image or a pattern;

- said at least one region of said colored grating has a length, in the X direction, greater than 3 millimeters, preferably greater than 4 millimeters and even more preferably greater than 5 millimeters.

As regards the choice of dimensions, the person skilled in the art will take care in particular to avoid the creation of a moiré effect likely to degrade the effect according to the invention.

In what follows, we consider lines in relief, colored bands or nets which extend along a preferred direction (X). The term “width” of a line in relief, of a colored band or of a net is therefore understood to mean the length, respectively of said line in relief, of said colored band or of said net, according to a cut made in one direction (Y) orthogonal to the preferred direction (X), in particular in the plane (X,Y) defined by said support or, where appropriate, by the surface of said support provided with said grating.

By “network of lines” is meant at least two lines, preferably at least three lines.

The term "line(s)" is used herein, although such lines should be considered as strips, i.e. elongated (extended) elements whose length is greater than the width. However, it is used here so as not to confuse raised bands (lines) with colored bands.

By "profile" is meant in particular the variation along the direction Z of the relief in the plane (X,Y).

By “ridge” and “furrow” is meant the highest points, respectively the lowest, of the lines in relief. The ridges, respectively the furrows, form respective lines whose width can vary or be constant.

By “line(s) in relief” is meant in particular one or more band(s) delimited by two ridges or two furrows.

By "consisting of a repetition of strips" is meant consisting of at least two strips, preferably of at least three strips.

By "net" is meant in particular an elongated (extended) element whose length is greater than the width.

“Different colors” means colors with different colorimetric coordinates, in particular in a colorimetric model chosen from among the following: CMYK, RGB, HSL, Lab, L*a*b* and Yxy.

By “support”, is meant in particular a support comprising a material made of paper, of fibrous material, of plastic material, or of a combination of at least two of these materials. The support can be transparent, translucent or opaque. The support can be colored or not. The support may further comprise a layer applied in and/or on the material, in particular a functional layer, for example a printability layer, a colored layer or a protective layer.

Said support is preferably a sheet material.

The lines in relief are for example produced by embossing and/or embossing, in particular according to the so-called dry stamp technique, namely in intaglio without ink.

The width L of the lines in relief is for example constant within said network in relief. It is preferably between 10 micrometers and 2 millimeters, preferably between 30 micrometers and 1 millimeter, more preferably between 300 and 500 micrometers.

The depth of the lines in relief is advantageously less than 200 micrometers, preferably between 50 and 150 micrometers, more preferably between 50 and 80 micrometers.

The ridges, respectively the furrows, for example form plateaus. Where appropriate, the width of said plates is preferably much less than the width of the lines in relief, for example at least five, preferably at least ten times smaller than the width of the lines in relief.

The width of the lines in relief is preferably much less than their length, for example at least five, preferably at least ten times smaller.

The profile of the lines in relief may have gradual variations in shape from one line to another, which result in particular in a gradual variation in the position of the crest or the furrow of this profile in the plane orthogonal to the direction X , and/or preferably gradual variations in shape along a determined line of direction X, which result in particular in a gradual variation in the position of the crest or of the furrow of this profile in the plane orthogonal to the direction X .

The colored bands are for example:

- produced by printing, in particular by offset, flexography, inkjet, laser, rotogravure, typography, and/or

- related to the surface structure, e.g. of the substrate, so that these include structural colors.

They are preferably produced by offset printing.

The colored bands are between 10 micrometers and 2 millimeters wide, preferably between 30 micrometers and 1 millimeter, more preferably between 300 and 500 micrometers.

The colored bands are advantageously contiguous, that is to say without space between them. However, it is possible to envisage that there is a space between them, of width less than the width of a colored band, preferably of width less than that of a net. Advantageously, this space has a width at least twice less than that of a colored band, preferably at least twice less than that of a net. This space is for example of a width of the order of 30 micrometers.

The threads are advantageously contiguous, that is to say without space d between them. However, it is possible to envisage that there is a space d between them, of width less than that of a net, advantageously of width at least twice less than that of a net. This space is for example of a width of the order of 30 micrometers. In particular, said space results from non-printing.

Each net can consist of the application on the substrate of a composition, for example of an impression of an ink or a varnish, preferably of an ink, and/or of structural colors.

If the backing of the security element, or where applicable its overlay with the security document, is color C, an absence of printing may form at least one rule of color C.

At least one thread, in particular all the threads, can be luminescent, in particular fluorescent. In this case, they may or may not be visible in daylight.

According to a particular embodiment, all the threads consist of an impression. Alternatively, at least one fillet, preferably a single fillet, consists of a composition reserve. In other words, it is not printed.

Said ink and/or said varnish can be transparent, opaque or translucent, and preferably opaque or translucent. Obviously, the transparent, opaque or translucent nature may depend on said application of a composition, in particular on parameters known to those skilled in the art, for example such as the mode of application, the thickness applied, the viscosity of the composition, the application temperature, the drying temperature, the drying mode, or the calendering or not.

Said ink and/or said varnish can be matte or glossy.

N is preferably greater than or equal to 3. Where appropriate, the threads are in particular of at least 3 different colors.

The width of said threads is preferably between 50 and 150 micrometers, preferably between 80 and 120 micrometers.

According to the invention, said N threads are of at least two different colors, the color of a thread resulting in particular:

- the superimposition of the support and said ink and/or said varnish,

- of the support alone, for example when the net consists of an ink reserve or in the case of structural colors, or

- said ink and/or said varnish alone, for example when said ink and/or said varnish is opaque.

According to a particular embodiment, the colorimetric difference ΔE of said at least two different colors is detectable with the naked eye. In particular, the colorimetric difference ΔE* in the L*a*b* CIE1976 colorimetric space of said at least two different colors is greater than 2, preferably greater than 3.

Another aspect of the invention relates to a secure document, characterized in that it comprises at least one security element according to one of the preceding characteristics.

Advantageously, said secure element is integrated therein or is added thereto.

When the security element is integrated into a secure document, said security document constitutes the support for the security element, and when the security element is attached to and/or in a security document, the support for the The security element is a separate element from the security document.

This secure document is for example a valuable document, preferably a banknote, which is made of paper, fibrous material, plastic material, or a combination of at least two of these materials.

According to the invention, said N lines are of at least two different colors, the color of a line being the color of one of the following components or resulting from the superposition of at least two of the following components:

- the support,

- said ink and/or said varnish,

- the secure document.

According to a particular embodiment, the colorimetric difference ΔE of said at least two different colors is detectable with the naked eye. In particular, the colorimetric difference ΔE* in the L*a*b* CIE1976 colorimetric space of said at least two different colors is greater than 2, preferably greater than 3.

Other characteristics and advantages of the invention will appear on reading the following description of preferred embodiments of the invention. This description is made with reference to the appended drawings in which:

there is a schematic top view of a secure document consisting of a banknote, which comprises a security element according to the invention;

there is a top view of a security element in accordance with document EP2691573 cited in the introduction;

there is an end view of the element of the previous figure;

there is an end view of the element of the , in a direction opposite to that of the ;

there is a partial cross-sectional view of the element of the , at the inflection point indicated in this figure;

there is a simplified top view of part of a colored network that the element according to the invention comprises;

there is a view analogous to , the colored network shown not however corresponding to a form of the security element covered by the invention;

there is a view analogous to , the colored network shown not however corresponding to a form of the security element covered by the invention;

there is a simplified top view of an embodiment of a network of lines in relief carried by the security element;

there is a view similar to the previous one, after simplification;

there is a view similar to the previous one, it being specified that here, the position of the crests of the lines in relief varies from one line to another;

there is a view analogous to , it being specified that here, the position of the crests of the lines in relief varies along each line;

there is a view analogous to , it being specified that here, the position of the peaks of the lines in relief varies in the opposite direction to that of the colored network represented in ;

there is a top view representing the superimposition of the colored and raised networks of FIGS. 3 and 7;

there is a view representing what is visible in grazing observation, for example from the bottom with an angle of inclination of 50° with respect to the normal, of the superposition of the ;

there is a top view representing the superposition of the colored and raised networks of FIGS. 3 and 8;

there is a top view representing the superposition of the colored and raised networks of FIGS. 3 and 9;

there is a top view representing the superposition of the colored and relief networks of FIGS. 3 and 10;

there is a top view representing the superimposition of the colored and relief networks of FIGS. 4 and 7;

there is a view representing what is visible in grazing observation, for example from the bottom with an angle of inclination of 50° with respect to the normal, of the superposition of the ;

there is a top view representing the superposition of the colored and relief networks of FIGS. 5 and 7;

there is a view representing what is visible in grazing observation, for example from the bottom with an angle of inclination of 50°, of the superposition of the ;

there is a top view of a network of colored bands forming a star, this network conforming to what is shown in ;

there is a top view of a network of raised lines with the position of the ridges varying inversely to that of the colored bands of the ;

there is a top view of a simulation of the superposition of the networks of FIGS. 20 and 21;

there is a top view of a raised line array according to the embodiment of the ;

there is a top view of a simulation of the superposition of the networks of FIGS. 20 and 23;

there is a top view of a network of colored bands forming a star, this network conforming to what is shown in ;

there is a top view of a network of raised lines with the position of the ridges varying inversely to that of the colored bands of the ;

there is a top view of a simulation of the superposition of the networks of FIGS. 25 and 26;

there is a top view of a network of colored bands forming a star, this network conforming to what is shown in ;

there is a top view of a network of raised lines with the position of the ridges varying inversely to that of the colored bands of the ;

there is a top view of a simulation of the superposition of the networks of FIGS. 28 and 29;

there is a top view of a network of colored bands forming the number "50", this network being in accordance with what is represented in the ;

there is a top view of a network of raised lines with the position of the ridges varying inversely to that of the colored bands of the ;

there is a top view of a simulation of the overlay of the networks of Figures 31 and 32.

Claims (18)

Security element (12) for a secure document (1) which consists of a support, comprising a network of parallel lines (2) in relief, in particular oriented along a preferred direction X, each of which has a width L, each line in relief (2) comprising a profile having at least one crest (21) and one furrow (20), said network being at least partly colored and consisting of a repetition of contiguous or adjacent strips (3), strips (3) of width L' each formed of N threads (30-32), N being an integer greater than or equal to two, contiguous or adjacent with, where appropriate, a space (d) between threads having a width smaller than the width d a thread, these N threads (30-32) being of at least two different colors (C1-C3) the said bands (3) extending substantially parallel to the lines in relief (2) of the said network, characterized in that , in at least one region of said colored network, the threads (30-32) of at least one strip (3) propagate from one end to the other of this region according to a continuous function F(x), partly differentiable and whose derivative is not constant and that there exists, within said region, an interval of length Li visible to the naked eye in which the derivative of said function F(x) is between L/(2Li) and 3L/Li, or between -3L/Li and –L/(2Li). Security element (12) according to Claim 1, characterized in that N is equal to 3. Security element (12) according to Claim 1 or Claim 2, characterized in that the said width L of the lines (2) in relief is constant within the said network in relief, preferably between 10 micrometers and 2 millimeters, preferably between 30 micrometers and 1 millimeter, more preferably between 300 and 500 micrometers. Security element (12) according to one of Claims 1 to 3, characterized in that the width L' of the said bands (3) is constant within the said colored network. Security element (12) according to Claims 3 and 4 taken in combination, characterized in that L is equal to L'. Security element (12) according to one of the preceding claims, characterized in that the depth of the lines in relief (2) is less than 200 micrometers, preferably between 50 and 150 micrometers, more preferably between 50 and 80 micrometers. Security element (12) according to one of the preceding claims, characterized in that the said space (d) between the said threads (30-32) has a width at least twice as small as the width of a thread. Security element (12) according to one of the preceding claims, characterized in that the said space between the said threads has a width of approximately 30 micrometers. Security element (12) according to one of the preceding claims, characterized in that Li is greater than 1 millimetre, preferably greater than 2 millimeters and even more preferably greater than 3 millimetres. Security element (12) according to one of the preceding claims, characterized in that the said at least one region of the said colored network has a length, in the said direction X, greater than 3 millimeters, preferably greater than 4 millimeters and even more preferably greater than 5 millimeters. Security element (12) according to one of the preceding claims, characterized in that the said profile has gradual variations in shape along a determined line of direction X which result in particular in a gradual variation in the position of the crest (21) or furrow (20) of this profile in the plane orthogonal to the X direction. Security element (12) according to one of the preceding claims, characterized in that the said profile has gradual variations in shape from one line to the other which result in particular in a gradual variation in the position of the crest ( 21) or the groove (20) of this profile in the plane orthogonal to the X direction. Security element (12) according to one of the preceding claims, characterized in that, within the said at least one region of the said colored network, the said gradual variation in the position of the crest (21) or of the groove (20) said profile describes a function kF, k being a non-zero constant. Security element (12) according to Claim 13, characterized in that the constant k is greater than or equal to -1 and strictly less than zero. Security element (12) according to one of the preceding claims, characterized in that the said at least one region of the said colored network is included in an image or a pattern (5,6). Secure document (1), characterized in that it comprises at least one security element (12) according to one of the preceding claims. Secure document (1) according to Claim 16, characterized in that the said security element (12) is integrated therein or is attached thereto. Secure document (1), in particular banknote, according to claim 16 or claim 17, characterized in that it is made of paper, of fibrous material, of plastic material, or of a combination of at least two of these materials.