RU2799931C2 - Security element of a valuable document, method for its manufacturing and a valuable document containing it - Google Patents

Abstract

FIELD: security elements; valuable documents.

SUBSTANCE: group of inventions relates to a security element of a valuable document, a method for its manufacture and a valuable document containing it. At the same time, the element (1) of protecting a valuable document (8) contains an array (R) of at least two lines adjacent to each other or adjacent to each other, (2, 2', 2ʺ), while these lines have longitudinal and opposite edges (200, 210), moreover, at least one of these lines (2) is in relief and has two opposite sides (20, 21), at least one of which has a part passing with an inclination relative to the plane (P), and each of which starts along one of the specified longitudinal and opposite edges (200, 210) of the specified line (2), while the specified two opposite inclined sides (20, 21) converge in a single and continuous area (22) of the connection of a wavy shape, which runs along the longitudinal direction of said line (2), wherein said lateral sides (20, 21) do not have breaks or interruptions, at least in said longitudinal direction.

EFFECT: security element of a valuable document.

22 cl, 100 dwg

Description

The field of technology to which the invention belongs

The present invention relates to a valuable document security element. It also relates to a method for manufacturing such a security element, as well as to a document of value containing at least one such security element.

State of the art

Protective devices, called first-level protective devices, i.e. those that are visible without additional equipment are effective protection against counterfeit security documents or valuable documents such as banknotes.

In addition, the producers of this type of document focus on the manufacture of these security features, making sure that they remain largely intuitive during their service life, but are difficult to manufacture without special knowledge and appropriate equipment and, of course, cannot be counterfeited. This means that the technologies used to make them are not readily available to the general public, and that the use of these tools is limited and/or specifically designed for specific document security operations.

Indeed, we are talking about elements whose authenticity can be easily established by each person, and which allow everyone to establish the authenticity of a document such as a bank note.

Document FR-A-2942811 discloses a technology for forming a security element containing an array of relief lines, each of which includes at least one side surface, the angle of inclination of which gradually changes along this line, in order to form an optical effect of smooth color transition upon reflection of light, which changes depending on the viewing angle of this element.

This document specifically describes the manufacture of a gravure plate made by laser engraving or a precision mechanical milling tool and having the aforementioned array of lines on its negative.

This plate is used as an embossing medium on a paper substrate containing a reflective surface such as iridescent or color changing ink. Alternatively, it is also possible to cover (cover) the previously embossed surface with ink.

More specifically, the width of one array line is 10 µm to 2 mm, and preferably 100 µm to 1 mm, and the height is 0 to 200 µm.

In practice, a line width of 400 µm and a line height that varies from 0 to 100 µm in steps are used, i.e. the minimum offset of the engraving tool and the size of the laser "spot" (actually active engraving area) that matches the resolution of the engraving tools commonly used to engrave gravure plates.

These dimensions are, of course, calculated in such a way as to obtain a visual effect when the document is tilted, preferably at an angle of the order of +90° to -90°, and more preferably at an angle of the order of +30° to -30°, which corresponds to the classic banknote tilt when checking it.

This security element occupies an area of the order of 2 cm ² , it being understood that the term "area" means the recommended surface over which the array passes to be convenient for viewing by the user.

This is at least 50 contiguous engraved lines (for example, on a 2 cm side) in a direction perpendicular to the main direction of the array.

These dimensions also represent the engraving limits for the tool used to create the engraving. Indeed, when the manufactured engravings are observed on a microscopic scale, they have a very disordered surface condition. The sides and bottom of the engraving are not smooth, with bumps and bubbles that are difficult to control. These defects are formed during the engraving steps as a result of partial melting of the laser engraved material or due to beads left by milling.

In addition, as mentioned above, the relatively large displacement step of the engraving tool and the resolution, that is, the size of the laser "spot" - of the order of 3-5 microns - (according to the corresponding resolutions from 8000 to 5080 dpi, dots per inch) limit the formation of a smooth surface and contribute to the formation of adjacent faces that are relatively discontinuous and separated from each other by sufficiently protruding edges.

Finally, the dimensions of these structures are adapted to the substrate on which they are applied, i.e. the paper. The latter itself has a certain surface roughness that is of the same order of magnitude as the engraving, resulting in a loss of optical effect quality line sought between the creation of structures in software and the final result.

Therefore, a need has arisen to improve this security element with the aim, in particular, of its miniaturization and maximization of its optical performance. By "miniaturization" is meant the visibility of the optical effect achieved with structures at least 10 times smaller (width and height/depth) than structures known from the prior art described above.

This is of particular interest when one wishes to use the security element on a security "thread" or "foil" rather than on the printed part of the document. Indeed, in the case of security threads, when integrated into a "window" in the paper, the visible portions of these threads are surfaces approximately 2 to 5 mm, preferably 3 to 4 mm wide, and in general 4 to 14 mm high, even if these visible surfaces tend to be maximized.

The term "foil" refers to a security element cold or preferably hot transferred directly to the surface of the paper in the form of an overlay or strip (running the entire height of the sheet/note).

There is a more modern version in which the patch or strip passes through a local hole formed in the substrate.

There are two main technologies: hot transfer, in which a carrier film is wound after a thin film containing security features has been transferred to a substrate, and lamination, in which a film carrying security features is directly applied to a substrate.

In all cases, if the surfaces limited by width and length are not a problem for the case of using "foil", the thicknesses available for the manufacture of a protective element, in accordance with the prior art known from document FR-A-2942811, are reduced and do not exceed a few tens of microns.

Thus, if the engraving known from the above document is used directly on a surface of 0.15 cm ² (in the case of using a thread where the average window is 3 × 5 mm), then it will be necessary to significantly reduce the number of engraved lines (more than 5 times) to the detriment of the visibility of the desired visual effect.

Another strategy could be to use the same engraving, i.e. the same engraved line 400 µm wide, but stretched to a width of 4 mm. The disadvantage of this method is that the angle formed by the side of the engraving becomes almost flat, namely less than 1°, and not of the order of 30°, as is the case when the line width is 400 μm. Thus, the effect of light reflection change, easily detectable by the naked eye on slopes that have become almost flat, is lost.

In addition, the engraving depth described in the same document varies from 0 to 200 µm, and in practice is in the order of 0 to 100 µm.

These depths are not applicable to the thread security element. Indeed, the thread is inserted into the paper during its manufacture and therefore must be thin enough so that its thickness does not exceed the thickness of the paper, which is about 100 microns.

As a result, the maximum possible thickness of the security thread, without in particular causing a problem with the strength of the paper in which it is inserted, is in the order of 40 to 50 µm. And if the functional layers (lacquer or protective layer, laminating adhesive, thermal adhesive, etc.) are removed from this thickness, a possible height of a few microns to 30 microns remains for the engraved element. This reduction in engraving depth helps smooth out the corners if it were to be transferred to the security thread unchanged.

The same reasoning applies, mutatis mutandis, to foils, in particular because of the aforementioned low thickness available, which also forces corners to be rounded off.

Thus, the engraving technique described in FR-A-2942811 is incompatible with all security elements, especially when they are in the form of thread or foil.

Thus, the object of the invention is in particular to provide a security element structure which is ideal for miniaturization, without adversely affecting the expected visual effect and even improving it.

It is also an object of the invention to develop a method for manufacturing such an element, in which the sides and bottom of the engraving, as well as the corresponding ridges, should be as smooth as possible, that is, with a minimum of defects and irregularities that are detrimental to the manifestation of light reflection effects.

Disclosure of the essence of the invention

Thus, the invention relates to a security element of a value document, which contains an array (R) of at least two adjacent or adjacent lines, at least one of these lines is embossed, and has two at least partially opposite inclined sides, each of which starts along one of the specified longitudinal and opposite edges of the said line, while, according to the invention, the said two opposite inclined sides meet in a single and continuous area of connection of a wavy shape, which runs along the longitudinal direction of the specified line, and the said side surfaces do not have breaks or interruptions, at least in the specified longitudinal direction.

This security element has a visual effect which leads to a gradual and controlled change in the light reflection when the substrate is tilted, said light reflection remaining unchanged even when the size of this security element is especially greatly reduced.

According to other advantages and non-limiting characteristics of this security element:

- the specified connection area has the form of a sinusoid;

- the specified sinusoid has a constant period over its entire length;

preferably said sinusoid has at least one period change along its entire length;

- the specified array (R) has a non-periodic structure;

- the relief of these at least two lines has a non-periodic change in height, width and/or length;

said joint area is parallel or substantially parallel to the plane in which said two longitudinal and opposite edges are located;

said joint area is perpendicular or substantially perpendicular to the plane in which said two longitudinal and opposite edges are located;

- the amplitude of the specified connection area is variable;

- the distance between the specified connection area and the plane in which the said longitudinal edges are located, is constant or variable;

- the specified connection area consists of a comb or, preferably, a strip;

- at least one of the said sides has a rectilinear or non-rectilinear slope;

- all lines of the specified array have the same width;

- said at least two lines have a non-triangular embossed profile; in width and/or length;

- at least one line of the specified array has a width different from the width of the other lines;

- at least one line of the specified array has a connection area, the shape of which is different from the shape of the connection area of other lines;

- said sides are inclined upwards or downwards relative to said longitudinal and opposite edges;

- the node contains a multilayer node, and the specified array is integrated into this multilayer node, and these additional layers are selected from the group consisting of dyes or pigment inks, color-changing pigment inks, liquid crystals, multilayer plastic films with a refractive index, optical interference filters with thin layers, metals obtained by the vacuum deposition method;

- the security element is a security thread, patch or foil.

The resulting visual effect preferably contains at least one of the following effects:

- change in contrast,

- reflection,

- alternating images,

- a gray level image, in particular by changing the light intensity,

- movement and/or displacement of light objects,

- the images appear in one or more planes other than the thread plane(s).

The additional layers mentioned above allow you to add other effects to the final structure. This is, in particular, the effect of changing the color of the structure according to the viewing angle, this effect is particularly achieved by using an additional layer selected from color-changing pigment inks, liquid crystals, multilayer plastic films with a refractive index and optical interference filters with thin layers.

The invention also relates to a method for manufacturing a tool for embossing security elements according to any of the above characteristics.

This method is notable in that it contains at least the steps of:

a) creating, i.e. manufacturing, a two-dimensional image characteristic of a portion of a line of said array, the image having a plurality of gray levels, a depth or height assigned to each gray level;

b) repeating step a) as much as necessary and assembling the same or different parts to form a line of the desired shape and length;

c) repeating steps a) and b) as long as necessary so that the lines are assembled in a continuous or contiguous manner to form sub-nodes;

d) if necessary, repeating steps a) to c) to achieve the final pattern;

e) from the image or final pattern obtained in steps a) to d) above, generating a three-dimensional image in which each point of this image has a location characteristic of a specified gray level;

f) proceeding to its 3D hardware fabrication in order to obtain the print characteristic of the image obtained in step e).

According to a specific embodiment of the invention, said preparation of the printed original is carried out by any of the following technologies: photolithography, in particular gray level photolithography, laser lithography, electron lithography or electron beam lithography.

Finally, the invention relates to a document of value, in particular to a banknote, which includes at least one security element according to any of the preceding characteristics.

Brief description of the drawings

Other characteristics and advantages of the invention will become apparent upon reading the following description of the preferred embodiments of the invention. This description is made with reference to the accompanying drawings, in which:

in fig. 1 schematically shows a three-dimensional partial view of an array of lines of a security element according to the invention;

in fig. 2 shows part of the line shown in FIG. 1 and presented in "gray levels";

in fig. 3 shows a more extended array line shown in FIG. 1 and presented in "gray levels";

in fig. 4 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 4A and 4B are sectional views of FIG. 4 in accordance with the planes IVA and IVB;

in fig. 5-10 are schematic views intended to illustrate certain specific shapes of the slanted sides of elements according to the invention;

in fig. 11 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 11A and 11B are sectional views of FIG. 11 in planes XIA and XIB, respectively;

in fig. 12 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 12A and 12B are sectional views of FIG. 12 in planes XIIA and XIIB, respectively;

in fig. 13 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 13A and 13B are sectional views of FIG. 13 in planes XIIIA and XIIIB, respectively;

in fig. 14 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 14A, 14B and 14C are sectional views of FIG. 14 respectively in planes XIVA, XIVB and XIVC;

in fig. 15 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 15A, 15B and 15C are sectional views of FIG. 15 respectively in planes XVA, XVB and XVC;

in fig. 16 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 16A, 16B and 16C are sectional views of FIG. 16 respectively in the planes XVIA, XVIB and XVIC;

in fig. 17 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 17A, 17B and 17C are sectional views of FIG. 17 respectively in the planes XVIIA, XVIIB and XVIIC;

in fig. 18 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 18A and 18B are sectional views of FIG. 18 respectively in planes XVIIIA and XVIIIB;

in fig. 19 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 19A-19E are sectional views of FIG. 19 respectively in the planes XIXA-XIXE;

in fig. 20 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 20A, 20B and 20C are sectional views of FIG. 20 respectively in planes XXA, XXB and XXC;

in fig. 21 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 21A and 21B are sectional views of FIG. 21 in planes XXIA and XXIB, respectively;

in fig. 22 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 22A and 22B are sectional views of FIG. 22 in planes XXIIA and XXIIB, respectively;

in fig. 23 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 23A and 23B are sectional views of FIG. 23 respectively in planes XXIIIA and XXIIIB;

in fig. 24 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 24A and 24B are sectional views of FIG. 24 respectively in planes XXIVA and XXIVB;

in fig. 25 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 25A and 25B are sectional views of FIG. 25 respectively in planes XXVA and XXVB;

in fig. 26 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 26A, 26B and 26C are sectional views of FIG. 26 respectively in planes XXVIA, XXVIB and XXVIC;

in fig. 27 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 27A, 27B and 27C are sectional views of FIG. 27 respectively in planes XXVIIA, XXVIIB and XXVIIC;

in fig. 28 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 28A, 28B and 28C are sectional views of FIG. 28 respectively in planes XXVIIIA, XXVIIIB and XXVIIIC;

in fig. 29 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 29A-29E are sectional views of FIG. 29, respectively, according to the planes XXIXA - XXIXE;

in fig. 30 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 30A, 30B and 30C are sectional views of FIG. 30 respectively in planes XXXA, XXXB and XXXC;

in fig. 31 is a plan view of part of an array line according to one embodiment of the invention, and FIG. 31A, 31B and 31C are sectional views of FIG. 31 in planes XXXIA, XXXIB, and XXXIC, respectively;

in fig. 32-36 are schematic sectional views of multilayer security elements according to the invention;

in fig. 37 shows a plan view of a banknote which combines two security features according to the invention;

in fig. 38-40 show three embodiments of elements according to the invention.

Implementation of the invention

In FIG. 1 shows a security element according to the invention.

This element is only partially shown to make the figure easier to see.

Thus, this member 1 is non-restrictively formed on a plastic material such as polyethylene terephthalate (PET) or biaxially oriented polypropylene (BOPP).

In the example shown here, element 1 includes an array R formed from three adjacent lines 2, 2' and 2". It is clear that an element having a much larger number of lines can be obtained. The length L of the lines in this particular case is identical and can range from a few millimeters to several centimeters. Only a part is shown here. Similarly, the width l of each of the lines in this particular case is identical and is a value between the lower limit that will diffract the incident light (about 1 μm, which should be avoided) and 10 0 µm to limit the pure reflection phenomenon, preferably the upper limit is less than 50 µm, and even more preferably less than 40 µm.

The height h, in turn, is, for example, from 1 to 50 µm, and preferably on the order of 10 µm or less.

Of course, in one of the embodiments not shown, lines of different widths l can be provided.

In the example shown, the lines 2-2" are straight lines. However, in one embodiment, not illustrated in the figures, the array R may contain lines having a curved, circular, and, more generally, any shape, or even one, for example, a spiral line, thus the array R is formed by many turns of the spiral.

As can be clearly seen in the figure, each of the three lines of the array R is embossed. However, it can be foreseen that some of them are embossed, while the rest of the lines are strictly flat. In this way, for example, it is possible to provide for alternating relief lines and flat lines. The presence of non-reflective, in particular transparent lines, can be used to identify visually distinguishable elements of information.

In the example shown, and in accordance with the invention, each of the relief lines 2 - 2" has two opposite sloping sides 20 and 21, each of which starts along one of the longitudinal and opposite edges 200 and 210 of the line. Here the sides are inclined upwards. This means that they run towards each other to a greater height than the longitudinal edges 200 and 210.

By "slanted sides" throughout this document is meant that at least a portion of at least one of the two sides is sloped. In other words, this does not rule out that the sides are locally vertical or horizontal.

Furthermore, in accordance with the invention, the two sides 20 and 21 meet in a single and continuous joint region 22 of a corrugated shape which extends along the longitudinal direction of the line, these sides 20 and 21 being without breaks or interruptions, at least in the longitudinal direction.

By "wavy shaped joint region" is meant that this wavy shaped joint region does not include a corner region. In other words, the projection of the connection area onto the plane of the array, and the projection of the connection area onto the plane orthogonal to the array and parallel to the lines, are described by a continuous function that is differentiable at any point. In addition, this connection area is continuous, as a result of which it extends in a uniform manner from one end to the other end of the line in question.

In the specific embodiment of the invention shown in FIG. 1, the connection area 22 has the shape of a sinusoid and is delimited by a line forming a ridge. In other embodiments, some of which will be described below, this joint area may not consist of a ridge, but of a strip of constant or variable width.

In addition, this region of the connection may have a shape other than the shape of a sinusoid, but still remain wavy.

Here the sinusoid has a constant period throughout its length. Also, neighboring lines are in phase (parallel evolution of connection areas), but of course it could be different. In addition, the amplitude of the sinusoid is equal to the width l of the line. In this case, again, it may be different. In particular, the sinusoid may have a variable period, adjacent lines may have a phase shift, and/or the amplitude of the sinusoid may differ from the width of the lines.

Finally, it should be noted that the plane in which this sinusoid passes is parallel to the plane P, which contains two longitudinal edges 200 and 210. In this case, as will be shown with reference to other figures, it may be different.

In addition, it should be noted that the sides 20 and 21 of each line have a straight slope from one of the longitudinal edges towards the connection area 22.

In FIG. 2 shows only one of the lines of the array R shown in FIG. 1. In addition, this line is represented by "gray levels". This means that a hue between white and black has been assigned to each point of this line, taking into account the rule that the farther the point of this line is from the above plane P, the darker its color. Thus, area 22 is represented in black. This grayscale representation is used to make this security element, as will be shown later in the description.

In FIG. 3 is a view equivalent to FIG. 2, except that line 2 has been shown having a large longitudinal extent.

In FIG. 4 is a plan view of the line shown in FIG. 2 and 3, and it is limited to displaying one cycle of the sine wave. Here it is even easier to distinguish different variations of gray, depending on the place in question. In the section in Fig. 4A, it is clearly seen that in this area, the connection area 22 is located on a vertical extending from the longitudinal edge 200. This figure also shows that the lateral side 21 has a rectilinear slope.

Fig. 4B illustrates the fact that according to the sectional plane shown here, the joint region 22 is located halfway between the two longitudinal edges 200 and 210. Reference numeral 23 denotes a straight line that extends vertically from region 22, however, this straight line does not actually exist.

Fig. 5 is similar to FIG. 4A and highlights the fact that the side 21 has a straight slope. In this figure, and henceforth, reference numeral h denotes the maximum height of the sinusoid 22.

In FIG. 6 to 10 show various general shapes (sections) of the lateral side 21, but this group of examples is not intended to be exhaustive. However, it should be pointed out that these descriptions are also valid for the second side 20, which has not been shown here. Of course, the sides 20 and 21 may have a different overall shape.

Thus, in FIG. 6, the lateral side 21 has a slightly convex slope, the convexity of which is directed from the base of the lateral side.

On the contrary, Fig. 7 refers to the lateral side 21, the slope of which has a slight concavity towards the base of the lateral side.

In FIG. 8-10 show embodiments of the invention based on the embodiments just described.

Thus, more specifically, in FIG. 8 shows a situation in which the lateral side 21 is inscribed in a straight line, but locally has a slight concavity (trough) indicated by 24, as well as a slight bulge (protrusion) indicated by 25.

In FIG. 9 shows a lateral side 21 which is generally convex but has an inflection point, i.e. a point with varying curvature towards edge 210.

With regard to FIG. 10, a lateral side 21 is described here, the shape of which is generally similar to that shown in FIG. 9, but locally with a slight concavity (depression) indicated by 24, and also with a slight bulge (protrusion) 25.

These protrusions, or "growths," and depressions, or "notches," create special sides of light reflection within the element in order to reveal the information that is on the bottom in accordance with the viewing angle.

In FIG. 11 is a view similar to that of FIG. 4 of one of the embodiments of the invention. Here again, the connecting region 22 is shown, which has the shape of a sinusoid, the amplitude of which is equal to the width l of the line. However, when considering FIG. 11A and 11B, it can be seen that the two sides 20 and 21 have a convex shape slope.

In FIG. 12 shows the variant shown in FIG. 11, in which, as shown in FIG. 12A and 12B, the sides 20 and 21 have a concave shaped slope.

The embodiment of the invention shown in FIG. 13 still refers to the connection area, which is in the shape of a sinusoid. However, here its amplitude is less than the width of 1 line. In addition, its sides 20 and 21 have a slope containing one or two straight sections, as shown in FIG. 13V. Indeed, in some areas of this line, each side 20 and 21 has an attachment part to the edges 200 and 210, which coincides with the previously mentioned plane P.

The embodiments of the invention just described have in common that the connecting region 22 is parallel to the plane P, which contains the longitudinal edges 200 and 210.

In particular, this does not apply to FIG. 14. Indeed, in this embodiment of the invention, if the connection area 22 still follows a sinusoid, then this sinusoid is unfolded in a plane perpendicular or substantially perpendicular to the above plane P.

Referring to FIG. 14A-14C show that the sides 20 and 21 are attached to opposite edges 200 and 210, these sides having a curved slope with an inflection point.

The embodiment of the invention shown in FIG. 15 has essentially the same characteristics as the embodiment shown in FIG. 14. However, the amplitude of the sinusoid is slightly smaller, and the sides 20 and 21 are slightly concave.

Similarly, in the embodiment shown in FIG. 16, 16A, 16B and 16C, we are essentially dealing with the embodiments shown in FIG. 14 and following, except that the maximum height of the junction area 22 remains stable for some distance such that it takes the form of a plateau.

In the embodiments just described, the joint area 22 has always been above the positions from which the sides 20 and 21 originate.

In FIG. 17 shows another situation in which the connection area 22 is always located at a level lower than the sides 20 and 21. This area has the shape of a sinusoid, the amplitude of which is less than the line width. In addition, its "height", that is, the distance with respect to the P plane, is not constant, as shown in FIG. 17A and 17B.

In FIG. 18 shows a situation relatively similar to that shown in FIG. 17. Again, the amplitude of the junction region 22 is less than the width l of the line, and on the side surface 21 there is locally a level difference here, which is a depression, indicated by the reference position 24.

In FIG. 19 schematically shows the situation in which the junction area is always in the form of a sinusoid. However, it does not deploy in a plane strictly parallel to the plane P, in which the longitudinal edges 200 and 210 are located. More specifically, as this line progresses in the longitudinal direction, the specified connection area approaches the above-mentioned plane P.

The embodiment of the invention in FIG. 20 describes the connection area, which is still inscribed in the sinusoid. However, this joint area is in the form of a strip, that is, it is not formed by a ridge, but has a significant transverse extension, as shown in particular in FIG. 20A.

In FIG. 21 shows a situation comparable to that shown in FIG. 4. However, it should be noted that the sinusoidal region 22 of the connection has an amplitude that is always less than the width of the line and is centered on this line, as a result of which each of the sides 20 and 21 is bordered in the direction of the longitudinal edges 200 and 210 by strictly flat areas coinciding with the above-mentioned plane P.

In FIG. 22 shows the connection area 22, which is always recessed with respect to the sides 20 and 21, as shown in particular in FIG. 22A and 22B. On the other hand, the amplitude of this connection area is still equal to the line width.

This does not apply to FIG. 23, where the sinusoidal region 22 of the connection has an amplitude smaller than the line width. In addition, here again this connection area is recessed relative to the sides 20 and 21.

In FIG. 24 shows the sinusoidal region 22 of the connection, the amplitude of which is less than the width of the line. In addition, as shown in the two sectional views in FIG. 24A and 24B, the sides 20 and 21 locally have either a horizontal (plateau) orientation or a combination of horizontal and oblique (oblique) orientations.

In FIG. 25 shows the shape of the sinusoidal connection region 22, relatively similar to the shape of the sinusoidal region shown in FIG. 23. However, as can be understood from FIG. 25B, in some areas of the longitudinal extent of the line, each of the sides 20 and 21 contains two straight sections of different orientation.

Fig. 26 represents an embodiment of the invention which is exactly opposite to the embodiment shown in FIG. 14. This means that the sinusoidal joint region 22 is deployed in a plane parallel to the planes containing the edges 200 and 210. However, the sides 20 and 21 are raised relative to said joint region at all times.

Fig. 27 illustrates a situation relatively similar to that shown in FIG. 26, except that the period and amplitude of the sinusoid constituting the junction region 22 are different.

In FIG. 28 shows an embodiment very similar to that shown in FIG. 27. It is characterized in that the sides 20 and 21 are not convex, but are concave.

Fig. 29 consists of a single module, mirror symmetrical horizontally and vertically. This base module has four corners. Height is set for each corner of this base unit. Opposite corners are at the same height. Two are at the maximum height and two are at the minimum. Thus, this module looks like the letter "X", the two opposite end sections of which rise up, and the other two fall down.

Fig. 30 illustrates the case where the sinusoid is not centered in the block. The connection area 22 has a continuous but irregular shape. The sides 20 and 21 have a variable amplitude depending on their position on the block. Thus, in the sectional view shown in FIG. 30A, the sides 20 and 21 consist of plateaus and increase/decrease in a perfectly symmetrical manner, whereas in the sectional view of FIG. 30B, the plateaus and slopes of the sides 20 and 21 are not symmetrical, thus giving the effect of a more or less narrow saddle.

Finally, the embodiment of the invention in FIG. 31 still describes the connection area as a sinusoid. It runs in a plane parallel to the aforementioned plane P, but it should be noted in particular when comparing FIGS. 31 and 31C that the period of this sinusoid varies along the longitudinal extent of the line.

After describing these various embodiments of the security element 1 according to the invention, we proceed to describe at least one example of the production of an imprint of such a security element.

For this description, reference will be made more specifically to FIG. 1, 2, 3 and 4.

Thus, in the first step, this method consists in creating, i.e. manufacturing, a two-dimensional image that is characteristic of a part of the line of the generated array R, and this image has a "multiple gray levels", with each gray level assigned a depth or height.

Preferably, this first step uses vector or bitmap graphics tools such as currently available software. Thus, a two-dimensional image is obtained, where a single segment is a period characteristic of a sinusoid. This single segment will be reproduced similarly to that shown in the above FIGS. 3 and 4, or attached to a new segment, whereby the resulting effect will be visually continuous and devoid of a visible connection point. At least two identical or different unit segments form the first block or the first part, which must be played as many times as needed.

In the second step, the step just described is repeated as many times as necessary, and different unit segments and/or identical or different blocks or parts are assembled to form a line of the desired shape and length. Of course, in order to maintain the continuity of the design, it is necessary to ensure that the start and end points of the connection area of each of the blocks connect to each other without a visible connection point.

Of course, this applies even if the connection area extends in a plane perpendicular to the aforementioned plane P.

In the next step, the previous steps are repeated as many times as necessary to create multiple lines that must be assembled in a continuous or contiguous manner to form sub-assemblies capable of generating optical effects visible to the naked eye. The lines of the array R of a subnode can be the same or different. Finally, everything is repeated again to reach, if this is the goal that has been set, the final drawing with these sub-nodes. It should be noted that in this case, the term "sub-assembly" refers to a three-dimensional structure, the optical effects of which are sufficient in themselves, since they are noticeable, and the assembly of identical or different sub-assemblies can be interrupted into connections (interruption of lines, sudden change in bending or even complete separation, but small enough to be imperceptible to the naked eye). According to a preferred embodiment, said assembly of identical or different sub-assemblies is performed with continuous connections.

In the next step, based on what has just been described, a three-dimensional image is created in which each point of this image has a gray level position characteristic, still using vector graphics tools. This image is then encoded in the specific language of the tool that generates the actual engraving features to be written as an imprint on the substrate to be engraved.

As a non-limiting example, each resulting line has the configuration shown in FIG. 3.

The next step of this method consists in preparing a printed photosensitive polymer original by engraving it three-dimensionally in order to obtain the engraving characteristics of the image obtained in the previous step.

This preparation of the printed original can be implemented, in particular, using the following technologies:

a) photolithography or optical projection lithography:

This involves exposing photons to a photosensitive resin through a template. In exposed areas, photons change the solubility of the resin. If the resin is positive, the exposed area is removed during development, and if negative, the exposed area is preserved during development;

b) gray level photolithography:

In this particular case, the pattern is a gray level pattern, so the opaque pixel densities are on a transparent bottom, the more or less exposed parts allow for different step heights to be controlled;

c) laser lithography

This technology is interesting in that it does not use a template. Lasers such as ultraviolet UV, nanosecond pulses, excimer, NdYAG, picosecond or femtosecond lasers are used directly on the resin.

The resolution in this case is about 0.8 µm.

d) electron lithography or electron beam (electron beam, e-beam) lithography:

This is a technology without the use of templates, in which patterns are created by direct scanning of an electron beam (from 10 to 100 electron volts) on a resin film. The resolution is equal to the diameter of the electron beam, which is several nanometers. The engraving depth is determined by the electron penetration, which is 100 nm.

What these technologies have in common is that they allow almost smooth and flat engravings. In other words, given the very small tool pitch (a few nanometers to 0.8 µm), the bottom of the engraving as well as the side of the engraving can be almost free of roughness, at least compared to the prior art described above.

However, if surface irregularities were still present, interfering with the reproduction and intelligibility of the desired optical effects, micropolishing could be provided. In this case, a single mirror is obtained on each line, which extends along the engraving direction and is curved in the shape of a side whose angles are continuously changing.

The subsequent steps in the manufacture of embossing elements (e.g. plates) are relatively conventional and require the conversion (electrodeposition, recombination, chromium electrodeposition, etc.) of a single element created in the preparation of a printed original to a multifunctional tool that will be used for thermoplastic embossing or embossing using ultraviolet radiation through a technology called "Nano Imprint" lithography (Nano-print).

In the previous part of the description, there is only a description of the single-layer security element. However, in a large number of situations this security element will be a multi-layered security element, and it is intended to describe some embodiments of it, in most detail, with reference to FIG. 32 - 36.

Thus, the embodiment shown in FIG. 32 refers to an assembly E which has a security element 1 according to the invention, consisting of a plastic film 3 coated with a lacquer 4, embossable. Thin layers of chromium 5, silicon oxide 6 and aluminum 7 are successively applied to this security element, but these examples are shown by way of illustration only. Of course, other sets of thin films with different materials and/or different number of layers can be provided to create noticeable visual effects. Then local removal of a part of aluminum 7 is performed to create holes 70.

According to this embodiment, an observer who looks at this assembly through the film 3 will notice a combination of several optical effects. Thus, layers 5, 6 and 7 cause the effects of changing the color of the structure in accordance with its viewing angle, for example, from magenta to green. This color changing effect is associated with a gradual change in the angle of the curved mirror composed of the security element 1, which causes a synergistic effect in which the engraving cavity is uniformly colored while the sides gradually change color to a green tint. It should be noted here that the security element 1 is shown rotated by 90° from the actual position to be located in the plane of the drawing, for better understanding.

In the embodiment shown in FIG. 33 are shown sequentially from top to bottom: a plastic film 3, an embossable lacquer 4, an aluminum layer 7 with holes 70, a silicon oxide layer 6 and a chromium layer 5. The protective element 1 is made in this node of layers superimposed on each other.

Another node E is shown in Fig. 34, the viewing side being a thin layer 5 of chromium.

The embodiment of the invention shown in FIG. 35 refers to a substrate 3 which includes a color change effect in itself or on its surface. It contains a refractive index changing laminate or at least one kind of liquid crystal ink. This substrate is coated with lacquer 4, which is deformed during its application by UV-assisted wet micro-reproduction (or Nano Imprint technology), resulting in the shape of the engraved instrument reproducing its imprint in the lacquer. The lacquer is then overlaid with a colored, eg black, layer 7 to reveal the combined effect of color shift and warped mirror when viewed through the substrate and in line with the printed areas 71. In the holes 70 corresponding to areas not covered with black ink, the effect of clear and transparent text is achieved.

In the embodiment of the invention shown in FIG. 36, the lacquer substrate 3 is located between the security element 1 and the layer 7. In addition, an additional layer 6 is provided behind it, the refractive index of which differs significantly from that of the lacquer of the lacquer substrate 3 of the element 1. This layer is preferably selected from high refractive index lacquers, such as the ZnS type, or low refractive index lacquers, such as perfluoropolyether.

Of course, additional layers used to make security features such as threads like masking layers, laminating layers with another plastic backing or thermal adhesive layers, protective layers, adhesive layers have not been shown in the figures just described for the sake of simplicity.

In FIG. 37 shows a banknote that has two security elements according to the invention, namely: on the left side, a security element 1 in the form of a rectangular block (overlay), and on the right, an element 1 in the form of a security thread implemented by forming a window.

In FIG. 38 shows an example of a security element 1 according to the claimed invention, which is a square-shaped pattern consisting of a series of subassemblies of ten lines whose sinusoids are in phase with each other to form an array. R. Each of these subnodes is vertically offset from its adjacent left and right subnodes. This offset is uniform until the middle of the image, where it is flipped. This results in a macroscopic herringbone effect capable of moving in accordance with the inclination of the substrate into which element 1 is inserted/fixed.

In FIG. 39 shows a second example of a security element 1 according to the principles of the present invention, which is a square-shaped pattern consisting of a series of subassemblies forming waves, stylized as the Great Wave off Kanagawa by the artist Hokusai.

In this particular case, the wave consists of two subnodes. The first sub-node consists of curved lines, the inner part of which expands as much as possible. A second subnode adjoins it, and its lines curve in the same direction as the first subnode, but the interior tapers to a minimum. This pair of adjacent sub-nodes is repeated and laid out in a tiled pattern so that no gaps are left between them. This leads to a macroscopic effect of waves capable of moving depending on the inclination of the substrate into which element 1 is inserted/fixed.

And finally, in FIG. 40 shows a third embodiment of a security element 1 in accordance with the present invention, which is a square-shaped pattern consisting of a series of sub-assemblies forming patterns of stylized boats sailing through a body of water. The body of water is constructed in accordance with Fig. 38 and the boats are built in accordance with FIG. 39, in particular with the first sub-assembly, consisting of curved lines, the inner part of which expands to a maximum, forming the hull of the vessel, and, identically, with the other sub-assembly, reproducing the sail. All these sub-assemblies are superimposed on each other, forming the overall image shown in Fig. 40.

These last three figures show a small overview of the possibilities of creativity. The layout possibilities of these subassemblies are almost limitless, resulting in any type of more or less figurative, more or less stylized image.

Claims (29)

1. An element (1) for protecting a valuable document (8) containing an array (R) of at least two lines adjacent to each other or adjacent to each other, (2, 2', 2"), while these lines have longitudinal and opposite edges (200, 210), and at least one of these lines (2) is in relief and has two opposite sides (20, 21), at least one of which has a part extending with an inclination relative to the plane (P), and each of which begins along one of said longitudinal and opposite edges (200, 210) of said line (2), characterized in that said two opposite inclined sides (20, 21) converge in a single and continuous area (22) of a wavy joint that runs along the longitudinal direction of said line (2), and said lateral sides (20, 21) do not have breaks or interruptions, at least in said longitudinal direction. 2. Element (1) according to claim 1, characterized in that said connection area (22) has the shape of a sinusoid. 3. Element (1) according to claim 2, characterized in that said sinusoid has a constant period over its entire length. 4. Element (1) according to claim 2, characterized in that said sinusoid has at least one period change along its length. 5. Element (1) according to any one of paragraphs. 1-4, characterized in that the specified array (R) has a non-periodic structure. 6. Element (1) according to any one of paragraphs. 1-5, characterized in that the relief of these at least two lines (2, 2', 2") has a non-periodic change in its length. 7. Element (1) according to any one of paragraphs. 1-6, characterized in that said connection area (22) is parallel or substantially parallel to the plane (P) in which said two longitudinal and opposite edges (200, 210) are located. 8. Element (1) according to any one of paragraphs. 1-7, characterized in that said connection area (22) is perpendicular or substantially perpendicular to the plane (P) in which said two longitudinal and opposite edges (200, 210) are located. 9. Element (1) according to claim 7 or 8, characterized in that the amplitude of said connection area (22) is variable. 10. Element (1) according to any one of paragraphs. 1-9, characterized in that the distance between said connection area (22) and the plane (P) in which said longitudinal edges (200, 210) are located is constant or variable. 11. Element (1) according to any one of paragraphs. 1-10, characterized in that said connection area (22) is a comb or, preferably, a strip. 12. Element (1) according to any one of paragraphs. 1-11, characterized in that at least one of said sides (20, 21) has a straight or non-straight slope. 13. Element (1) according to any one of paragraphs. 1-12, characterized in that all lines (2, 2', 2") of the specified array (R) have the same width. 14. Element (1) according to any one of paragraphs. 1-13, characterized in that said at least two lines (2, 2', 2") have a non-triangular relief profile in width and/or length. 15. Element (1) according to any one of paragraphs. 1-12, 14, characterized in that at least one line (2, 2', 2") of the specified array (R) has a width different from the width of other lines. 16. Element (1) according to any one of paragraphs. 1-15, characterized in that at least one line (2, 2', 2") of the specified array (R) has a connection area (22), the shape of which differs from the shape of the connection area of other lines. 17. Element (1) according to any one of paragraphs. 1-16, characterized in that said sides (20, 21) are inclined upwards or downwards relative to said longitudinal and opposite edges (200, 210). 18. Element (1) according to any one of paragraphs. 1-17, characterized in that it contains a multilayer assembly (E), wherein said array (R) is integrated into said multilayer assembly (E), wherein said multilayer assembly contains additional layers selected from the group consisting of dyes or pigment inks, color-changing pigment inks, liquid crystals, multilayer plastic films with refractive index change, optical interference filters with thin layers, metals deposited by vacuum deposition. 19. A method of manufacturing a protective element (1) according to any one of paragraphs. 1-18, containing the steps in which a tool for embossing a security element (1) is made, including: a) creating, i.e. producing, a two-dimensional image representative of a portion of the line (2, 2', 2") of said array (R), the image having a plurality of gray levels, with each gray level assigned a depth or height; b) repeating step a) as many times as necessary and assembling the same or different parts to form a line of the desired shape and length; c) repeating steps a) and b) as many times as necessary to connect the lines in a continuous or contiguous manner, forming sub-nodes; d) if necessary, repeating steps a) to c) to obtain the final drawing; e) from the image or final pattern obtained in steps a) to d) above, generating a three-dimensional image in which each point of this image has a location characteristic of a specified gray level; f) making said tool using 3D hardware and characterizing the imprint of the image obtained in step e) on said tool, and - the step of embossing the security element (1) with the tool obtained in steps a) to f). 20. The method according to claim 19, characterized in that said preparation of the printed original is carried out by implementing any of the following technologies: photolithography, in particular gray level photolithography, laser lithography, electron lithography or electron beam lithography. 21. Valuable document, characterized in that it contains at least one security element according to any one of paragraphs. 1-18. 22. Valuable document under item 21, characterized in that it is a banknote.