EP0146151B1 - Security paper - Google Patents

Abstract

The document of value is provided with a safety design extending on one portion or the whole of its surface. The entire surface of the safety design consists of juxtaposed groups of segments of raised parallel lines of two different heights forming high reliefs and low reliefs portions. The segments of two adjacent groups are parallel to two predetermined directions, preferably substantially perpendicular. The assembly of segments parallel to one of the directions and consisting of high reliefs on the whole or part of their length define a transitory image visible when the document is illuminated or observed parallel to a direction perpendicular to said segments and forming an acute angle with the plane of the document of value. A second transitory image is formed in a similar manner by high relief segments parallel to the other direction. The low raised segments or segment fractions constitute the background of the safety design. All the raised segments and the gaps left between the segments have preferably the same color.

Description

The present invention relates to a security paper having a security design as defined by the preamble of claim 1.

In order to avoid the issuance of false security papers, particularly banknotes, different printing methods were used and security papers were notably provided with security drawings made up of thin lines of different colors forming complex figures so that reproduction by photographic means is difficult. However, the evolution of reproduction techniques has enabled counterfeiters to overcome this difficulty, at least in certain cases. Another solution has been the manufacture of valuable papers, at least part of the surface of which comprises relief lines produced by the so-called intaglio process. Several variants have been proposed on the basis of this process. In particular, it has been proposed to produce a transient image formed by parallel raised lines. According to one variant, the transient image is only detectable through an appropriate transparent screen, or by illuminating the value paper with an appropriate light. In another case the color of the sides of raised lines varies along its length or d 'one side to the other so that when looking at the banknote from two different angles you can see two different images depending on whether one or the other side of raised lines is hidden. Finally in another case the lines in relief have a uniform color contrasting with that of the paper (the spaces between the lines), so that the image formed by these raised lines only appears when looking at the drawing from a relatively small acute angle and parallel to a plane perpendicular to these lines, which in this case hide the spaces between them and reveal a uniformly colored image. This image is difficult to detect if we look at the drawing in a direction perpendicular to its plane because the contrast of the colors between lines and between lines breaks down the image.

These solutions have contributed to making it difficult if not impossible to manufacture false value papers because no photographic device can produce a three-dimensional reproduction. However, the variants cited first have the drawback of requiring an additional device (screen, lens, special light lamp, etc.) to carry out the authenticity check and therefore to make it almost impossible during the current use of papers. value. As for the last two variants, they require very high precision for the production of transient images in order to obtain a perfect register of colors. On the other hand the angle of observation is relatively small, of the order of 15 ° to 20 ° relative to the plane of the paper, which makes the control of a large number of valuable papers tedious.

In patent FR-A-2192496, a safety design has been proposed corresponding to the preamble of claim 1 of this patent. According to an alternative embodiment described but not illustrated by a figure of this French patent, the transient images consist of several letters and are formed by the portions of the lines having an increased thickness. Some letters are formed by the parts of the lines parallel to one of the two directions, while the other letters are formed by the parts of lines parallel to the other direction. Thus, to be able to distinguish the two groups of letters, the document must be rotated by an angle equal to the angle formed by the two directions. However, these two images are not superimposed or interposed but only juxtaposed, in addition the background of the security design is formed on the one hand of the lines in low relief and on the other hand of the paper itself.

The purpose of the present invention is to remedy the drawbacks of the prior art and to propose an alternative to the security design of patent FR-A-2192 496 making counterfeiting more difficult by allowing, on the one hand, a security drawing on valuable paper using the intaglio process, without involving any color contrast and on the other hand, the security drawing can easily be detected by a layman without having to resort to auxiliary means such as a lamp, screen, lenses, etc., and at a relatively large acute angle.

The security design according to the invention is characterized by the characterizing clause of claim 1.

The advantages of the subject of the invention are as follows: The entire safety drawing and not only the transient images is formed of two networks of groups juxtaposed with segments in relief in parallel respectively and alternately in two predetermined directions. Certain parts of the images appearing from different angles are interleaved, that is to say in some way superimposed. For each image, even the superimposed parts are formed by the high reliefs of the segments belonging to one of the networks. The peripheries of the groups of each network define planar geometric figures which are the same for a given network and are completed by the geometric figures defined by the peripheries of the groups of the other network. The groups of segments are easily obtained by intaglio printing and without being obliged to resort to meticulous adjustments in order to respect the color register, the whole of the safety design, raised segments and between segments, preferably being of the same color. The authenticity can be checked by any user, either by illuminating the design with natural light or an electric lamp, or more simply by looking at it at an acute angle and parallel to a plane perpendicular to the raised lines forming one of the images. A rotation of the value paper by an angle approximately equal to the angle between the two predetermined directions to which the segments of two adjacent groups are respectively parallel, makes the second image appear.

The fact that an image appears when the drawing is illuminated at an acute angle and parallel to a plane at least approximately perpendicular to the raised segments composing the image, is due to the fact that the segments whose height is greater than that of segments making up the background of the drawing, or rather the groups of segments appear to have a darker color because of the shadow cast by the segments on each other and the fact that the density of the segments seems to increase when observed in a direction perpendicular and at an acute angle with respect to their support. It is obvious that to obtain these results it suffices that the lighting or observation angle is simply less than 90 °.

By observing the paper perpendicular to its plane, no image can be distinguished, especially since the groups comprising the segments making up the two images are, at least for part of them, adjacent, so it can be said that the images are partially mixed .

According to a preferred variant, the two directions to which the raised segments are parallel are perpendicular and the geometric figure determined by the periphery of a group of segments is a rectangle, in particular a square.

• La figure 1 est une vue en perspective d'un dessin de sécurité faisant apparaître une première image.
• La figure 2 est une vue similaire à celle de la figure 1 faisant apparaître une seconde image.
• La figure 3 est une vue en coupe d'une partie agrandie d'un papier valeur montrant les différents éléments en relief.
• La figure 4 est une vue en perspective fortement agrandie d'une partie d'un dessin de sécurité.
• La figure 5 représente un billet de banque avec le dessin de sécurité.
• La figure 6 est une vue fortement agrandie en plan d'une partie du dessin de sécurité.

The invention will be described in more detail using the attached drawing.

• Figure 1 is a perspective view of a safety drawing showing a first image.
• Figure 2 is a view similar to that of Figure 1 showing a second image.
• Figure 3 is a sectional view of an enlarged portion of a value paper showing the various elements in relief.
• Figure 4 is a greatly enlarged perspective view of part of a safety drawing.
• Figure 5 shows a bank note with the security design.
• Figure 6 is a greatly enlarged plan view of part of the safety drawing.

The safety drawing S shown in FIGS. 1 and 2 of a paper P value is made up of raised straight lines arranged in groups 1.2 juxtaposed. Figure 6 shows some of these groups on a large scale. The segments of two adjacent groups 1, 2 are parallel to two perpendicular directions. The relief segments are shown in black, but in reality the color of the relief segments, and the space between two segments is the same. There may be a difference, between the raised segments and the space between two raised segments, if the paper backing is of a color contrasting with the color of the printing ink of the security drawing due to the difference of the thickness of the ink layer between a raised segment and the space between two segments as will be seen below.

Generally and subject to the above-mentioned remark, the safety drawing appears, observed perpendicular to its plane, as having a uniform color. The figures delimited by the ends of the segments and the extreme segments of each group 1, 2 form a square. However, any other figure may be produced provided that the peripheries of two adjacent groups are combined so that the entire background of the drawing is continuously covered.

By illuminating or observing the drawing at an acute angle and parallel to the direction D, which is at least approximately perpendicular to one of the directions to which the segments are parallel, we see appear a first image which is an A, this image is formed by segments and fractions of the raised segments of a height higher than that of the other segments, respectively fractions of segments, and perpendicular to the direction D. If one turns the paper value P of 90 ° one sees the second appear image which is in this case a Z (the letters A, Z on the periphery of the drawing constitute only landmarks for understanding the figures). This second image is formed in the same way as the previous one, but by segments perpendicular to the segments of the previous image.

Of course if the two predetermined directions to which the segments are parallel are not perpendicular, then the rotation of the P value paper must be made at an angle equal to the angle of these two directions.

In Figure 3 we see in section the different elements of the safety drawing. The P value paper is covered with a layer of ink 3 having three different levels. The lowest level n1 is the level between the raised segments. Then there is the level n2 which is that of the low relief segments. Levels n1 and n2 form the background of the security drawing. The level n3 is that of the segments or fractions of segments in high relief making up one or the other of the transient images.

By way of example, the segments 4 and 5 belonging to two adjacent groups are segments or fractions of segments in low relief and therefore belong to the security design background. The segments 4 are perpendicular to the plane of Figure 3 and the segment 5 parallel to this plane. The segment 7 which is parallel to the segments 4 is a segment the upper part of which is along its entire length or a fraction at the highest level n3 and contributes to the composition of one of the transient images. The top of segment 6, which lines up with segment 5, is on two levels. A first part is at level n3 therefore in high relief, and contributes to the composition of the other transient image and two other parts are at level n2 therefore in low relief, and form part of the background of the drawing.

The detail illustrated in enlargement in FIG. 4 also shows the constitution of the safety drawing. The groups with segments parallel to the front edge F of the value paper P are all part of the background of the drawing, while the segments perpendicular to the edge F, belonging to the other groups, compose a transient image. The segment 8 has an upper part which is at level n3 and another which is at level n2. The segments belonging to the same group as segment 8 also have their upper part at level n3. Segment 9 and those of its group also have two different levels extending over unequal lengths, it is the same for segment 10. The other illustrated segments, parallel to segment 10, are of level n3. All the segments or part of segments of level n3 contribute to the composition of an image which can be observed if we illuminate the drawing or if we look at it in a direction parallel to D '.

The security drawing can occupy either part of a valuable paper, as illustrated in FIG. 5, or the entire surface of the paper.

• n1 = 0,03 mm
• n2 = 0,07 mm
• n3 = 0,14 mm

-The depositor produced a security drawing on a bank note according to the intaglio process using the following sizes for the three levels relative to the surface of the value paper.

• n1 = 0.03 mm
• n2 = 0.07 mm
• n3 = 0.14 mm

Claims (4)

1. A document of value (P) having a safety design (S) formed by two networks of raised line segments being parallel to two predetermined different directions, respectively, and having two different heights (n2, n3) forming high and low raised relievos extending on one portion or the whole of said document of value (P), comprising a background and at least two transitory images (A, Z) which are formed respectively by the line segments having high raised relievos (n3) parallel to the one and the other of the predetermined different directions respectively, an image becoming visible when the design (S) is illuminated by light rays forming an acute angle with the plane of the design and parallel to a plane at least substantially perpendicular to the direction in which the image forming segments are parallel or when the design (S) is observed from an acute angle and in a direction parallel to a plane at least substantially perpendicular to the direction to which the image forming segments are parallel, characterised by the fact that the whole of the surface of said safety design (S) consists of juxtaposed groups (1, 2) of parallel line segments extending alternately in the two predetermined different directions so that the segments of one group (1) are not parallel to those of an adjacent group (2), that the periphery of each group (1, 2) defines a plane geometrical pattern which is the same for all the groups of segments parallel to the same direction and is completed by the peripheries of the adjacent groups for forming the surface of the design (S), the first transitory image (A or Z) being formed by the high raised relievos (n3) of segments parallel to the first direction and pertaining to several groups (1 or 2), whereas the second transitory image (Z or A) is formed by the high raised releivos (n3) of the segments parallel to the second direction and pertaining likewise to several groups (2 or 1), that at least one portion of the segments forming said two images (A, Z) pertains to adjacent groups (1, 2), and that the segments or segment portions having the low raised relievo form with the gaps left between the segments the background of the safety design (S).

2. Document of value according to claim 1, characterized by the fact that the plane geometrical patterns defined by the peripheries of the groups (1, 2) of segments are rectangles, notably squares.

3. Document of value according to claim 1 or 2, characterized by the fact that the two predetermined directions are perpendicular to each other.

4. Document of value according to any of claims 1 to 3, characterized by the fact that all the safety design (S), raised segments and gaps between segments, has the same color.

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