EP1803038B1 - Security feature for security documents - Google Patents

Abstract

The invention relates to a security feature (8) for security documents (9), in particular bank notes. A first body colour (51) is applied in a first region (1) and a printing ink (53), in particular a day luminescent dye, is applied in an illuminating region (3). The printing ink (53) is applied outside the copy dye range of the four colour prints according to the Europe-scale or DIN-scale. According to the invention, a first mixed colour (54) of the first body colour (51) and the printing ink (53) is applied in a first overlapping region (13), and the first mixed colour (54) is arranged outside the copy dye range or in the edge region of the copy dye range, in order to increase protection against forgery.

Description

The invention relates to a security feature for security documents, in particular banknotes, wherein in a first area a first body color and in a luminous area a printing ink, in particular a daylight color, is applied, the ink outside the copy color space of four-color printing according to the Europa scale or DIN Scale is located.

It is known to provide security documents with security features which are intended to make the production of a forgery more difficult and are used for the authenticity check of the security document. Particularly easy falsification can be generated by means of a color copier, the differences of these counterfeits due to the increased resolving power and improved color formulation of color copiers compared to the original have become smaller and therefore the provision of new security features is desirable, which are not reproducible by means of conventional color copier.

The US Pat. No. 4,066,280 discloses a security document having a first imprint and a second imprint, wherein the second imprint is opaque and can not be copied by a copier. The second imprint can consist of a silver color.

From the EP 0 603 117 It is known to use colorants for the printing inks, which differ as much as possible from the toners used in conventional color copiers, whereby a color difference between the original and the color copy is achieved. The use of fluorescence effect colorants is also proposed. A disadvantage is that this security feature is not suitable for the assessment of anyone, since a comparison with an original security document is required to secure a forgery. If the color difference occurs only with a specific type of illumination, then the production of this type of illumination is often difficult to achieve.

The object of the invention is to provide security features of the type described above, in which the known disadvantages are avoided and which have a high security against counterfeiting, in particular with regard to color copying or scanning. Another object of the invention is also to facilitate color blind the detection of counterfeiting.

According to the invention, this is achieved in that a first mixed color of the first body color and the printing ink is formed in a first overlapping area, and the first mixed color is located outside the copy parb space or in the edge area of the copying color space.

This results in the advantage that the first area, the first overlap area and the luminous area can be formed distinguishable from each other on the original security feature, but in color copies the ink can not be reproduced faithfully and the first overlap area and the luminous area in the color copy can be formed coincidentally, wherein a differentiation of these areas only at a strong color distortion of the color copy, which also affects the other areas, can be achieved. This makes a color copy easy to distinguish from an original safety feature. Furthermore, the fluorescence of the ink represents another security feature, wherein the different luminous intensity of the luminous area and the first overlap area can be used in the illumination with UV light to verify the authenticity of the security feature.

In a further development of the invention, it may be provided that the first overlap region is arranged adjacent to the first region and adjacent to the luminous region, whereby the detection of color differences in these regions is facilitated.

In a further embodiment of the invention can be provided that the maximum of the reflection curve of the first mixed color is greater than the maximum of the reflection curve of the first body colors. As a result, a high copy security of the security feature can be achieved.

In a continuation of the invention it can be provided that the intensity of the reflection curve of the first mixed color at the maximum is greater than 90%, preferably greater than 95%, in particular greater than 100%. At these intensities, it can be ensured that fluorescent properties of the printing ink also occur in the case of the first mixed color.

According to another embodiment of the invention, provision can be made for a second body color to be applied in a second area, and for a second mixed color of the second body color and the printing ink to be formed in a second covered area, and for the second mixed color to be located outside the copy color space is. By providing the second mixed color, the copy security of the security feature according to the invention can be further increased.

In this context, it can be provided in a further embodiment of the invention that the second overlap region is arranged adjacent to the second region and adjacent to the luminous region, whereby color differences in the different regions are particularly easy to detect.

In a further embodiment of the invention it can be provided that the maximum of the reflection curve of the second mixed color is greater than the maximum of the reflection curve of the second body colors. As a result, a high copy security of the security feature can be achieved.

In a development of the invention, it can be provided that the intensity of the reflection curve of the second mixed color is greater than 90% at the maximum, preferably greater than 95%, in particular greater than 100%. At these intensities, it can be ensured that fluorescent properties of the printing ink also occur in the case of the first mixed color.

According to another embodiment of the invention, it can be provided that one of the body colors has a higher proportion of a first base color and a lower proportion of a second base color than the other of the body colors, wherein the proportion of the third base color in the ink is smaller than the proportion of and the first base color, the second base color and the third base color are selected from the set of primary colors red, green and blue. As a result, the recognition of the authenticity of the security feature can also be facilitated for colorblinds, for example for red-green-blind persons when using a yellow printing ink. Furthermore, even with a possible change in the settings of a copier, a different formulation for the first overlap region, the luminous region and the second overlap region can be avoided, as a result of which a color copy can easily be detected as a forgery.

A variant of the invention may consist in that the first body color is essentially a complementary color of the second body color. By using complementary colors, a particularly high level of copying security can be achieved, since a change in the settings of the color copier has different effects on the body colors and an increase in the contrast of the first mixed color with the ink causes a deterioration in the contrast of the second mixed color with the ink.

The invention further relates to a security document, in particular a banknote.

The object of the invention is to provide a security document of the type described above, in which the known disadvantages are avoided, which has a high anti-counterfeiting protection against color copies.

According to the invention this is achieved with a security feature described above.

It can be provided that in a color copy by means of a copying machine with basic setting, the printing ink and the first mixed color with a color difference delta E of less than 3, preferably less than 2, in particular less than 1, are reproduced, wherein in the default setting the average deviation of colors in the copy color space with the colors on the color copy is as small as possible. This can ensure that in a color copy with basic setting the formulation of the ink and the first mixed color largely coincide, which due to the lack of contrast a color copy is easily detected as a forgery.

Furthermore, it can be provided that in a color copy by means of a copying machine with basic setting, the printing ink and the second mixed color with a color distance delta E of less than 3, preferably less than 2, in particular less than 1, reproduced. In this way, it can be ensured that in the case of a color copy with the basic setting, the formulation of the printing ink and the second mixed color largely coincide, whereby a color copy can easily be detected as a counterfeit due to the lack of contrast.

• Fig. 1 eine Ausführungsform eines erfindungsgemäßen Sicherheitsmerkmals;
• Fig. 2 eine Farbkopie des Sicherheitsmerkmals nach Fig. 1 bei Grundeinstellung des Farbkopierers;
• Fig. 3 eine Farbkopie des Sicherheitsmerkmals nach Fig. 1 bei Einstellung des Farbkopierers auf kalte Farben;
• Fig. 4 eine Farbkopie des Sicherheitsmerkmals nach Fig. 1 bei Einstellung des Parbkopierers auf warme Farben;
• Fig. 5 die Reflexionskurven im sichtbaren Bereich der Farben des Sicherheitsmerkmals nach Fig. 1; und
• Fig. 6 ein erfindungsgemäßes Sicherheitsdokuznent.

The invention will be further described with reference to the accompanying drawings, in which embodiments are shown. Showing:

• Fig. 1 an embodiment of a security feature according to the invention;
• Fig. 2 a color copy of the security feature Fig. 1 at basic setting of the color copier;
• Fig. 3 a color copy of the security feature Fig. 1 when the color copier is set to cold colors;
• Fig. 4 a color copy of the security feature Fig. 1 when setting the Parabkopierers on warm colors;
• Fig. 5 the reflection curves in the visible range of the colors of the security feature Fig. 1 ; and
• Fig. 6 an inventive security Dokuznent.

In Fig. 1 an embodiment of a security feature 8 according to the invention for security documents 9 is shown. The security document 9 can in particular be a banknote, as in Fig. 6 be shown. In other embodiments, the security document may also be a security, a deed, a contract, or other security document. The security feature 8 has a first body color 51 in a first region 1 and a printing ink 53 in a luminous region 3, the ink 53 being outside the copy color space of the four-color printing according to the Europa scale or DIN scale. The body color 51 may be a base color or a recipe of different colors. Likewise, the ink 53 may be formed as a recipe of different colors.

The copy color space results from the colors used in four-color printing and is specified in terms of the Europe scale in DIN 16538 and DIN 165309 and in terms of the DIN scale in DIN 16508 and DIN 16509.

The printing ink 53 may in particular be a daylight color. Fluorescent inks are fluorescent colors that glow intensely in the visible region of the spectrum under ultraviolet radiation. For example, in addition to the visible range, these colors also evaluate the ultraviolet rays of daylight, whereby the daylight colors are among the most brilliant of all colors thanks to this double color effect. In other embodiments, the ink 53 may include special effect colors, in particular, interference pigments, liquid-crystalline colors or pearlescent pigments may be provided. The ink 53 may also be a recipe of daylight colors and special effect colors.

The color space is understood here to be the CIELab system, and the color difference in the CIELab system is understood by the Delta E color distance evaluation. The copy color space is thus the color space in the CIELab system, which is determined by the colors specified in the European scale or DIN scale for four-color printing. The colors of a color copy are created by subtractive color mixing.

In a first overlapping area 13, a first mixed color 54 of the first body color 51 and the printing ink 53 is formed, wherein the first mixed color 54 is located outside of the copying color space or in the edge area of the copying color space.

The overlapping area 13 and the first mixed color can be easily formed by overprinting a part of the first body color 51 with the ink 53. In other embodiments, the ink 53 may also be overprinted with the first body color 51 or the first color 54 may be printed directly. It is advantageous if the first overlap region 13 is arranged adjacent to the first region 1 and the luminous region 3, as a result of which color differences of these regions can also be easily determined.

Good copy protection can be achieved if the original 53, the ink 53 differs from the first mixed color 54, in a color copy by means of a copier with basic setting the ink 53 and the first mixed color 54 with a Color distance evaluation delta E of less than 3, preferably less than 2, in particular less than 1, reproduced. The basic setting is the standard setting of a color copier, where the average deviation of colors in the copy color space from the colors on the color copy is as small as possible.

In addition to this basic setting, copiers can usually also be set to the "cold" or "warm" setting, where additional weighting of the colors is carried out during formulation.

In Fig. 5 the reflection curves are shown in the visible range of the colors of the security feature 8. A substantially similar formulation of the printing ink 53 and the first mixed color 54 can be achieved in a simple manner if the intensity of the first body color 51 in the visible range is substantially below the intensity of the ink 53, with a slight excess in areas of low intensity has shown insignificant.

As a criterion, it seems to be significant that the maximum of the reflection curve of the first mixed color 54 is greater than the maximum of the reflection curve of the first body color 51. Furthermore, it has proven to be favorable if the intensity of the reflection curve of the first mixed color 54 at the maximum is greater than 90%, preferably greater than 95%, in particular greater than 100%. These high intensities can be achieved due to the fluorescent properties of the ink 53.

The reliability of the security feature 8 according to the invention can be increased if a second body color 52 is applied in a second area 2 and a second mixed color 55 of the second body color 52 and the ink 53 is formed in a second overlap area 23, the second mixed color outside the copy Color space is located.

The second mixed color 55 can be easily produced by overprinting a portion of the second body color 52 with the ink 53. It is advantageous here if the second overlapping region 23 is arranged adjacent to the second region 2 and adjacent to the luminous region 3.

For the second body color 52 and the second mixed color 55, the same applies to the first body color 51 and the first mixed color 54. In particular, it appears favorable if the intensity of the second body color 52 in the visible range is substantially below the intensity of the printing ink 53, with a slight exceeding in areas of low intensity having been found to be insignificant.

Good copy protection can be achieved if, in a color copy by means of a copier with basic setting, the printing ink 53 and the second mixed ink 55 are reproduced with a color difference delta E of less than 3, preferably less than 2, in particular less than 1.

In this case, the maximum of the reflection curve of the second mixed color 55 should be greater than the maximum of the reflection curve of the second body color 52. Furthermore, it has proven to be favorable if the intensity of the reflection curve of the second mixed color 55 at the maximum is greater than 90%, preferably greater than 95%, in particular greater than 100%. These high intensities can be achieved in a simple manner, in particular when using a daylight color as printing ink 53, on account of the fluorescent properties.

A particularly good copy protection results when the first body color 51 is essentially a complementary color of the second body color 52. As a result, even if the settings of the copier are changed, the security feature can not be reproduced so that the color copy is not immediately recognized as a color copy. If a setting is selected which enhances the contrast between one of the mixed colors 54, 55 and the printing ink 53, the contrast between the printing ink 53 and the other of the mixed colors 54, 55 is reduced in this setting.

It has been found that good results are also achieved if one of the body colors 51, 52 has a higher proportion of a first base color and a lower proportion of a second base color than the other of the body colors 51, 52 The proportion of the third base color is smaller than the proportion of the first base color and the second base color, and wherein the first base color, the second base color and the third base color are selected from the amount of the primary colors red, green and blue. When using a printing ink 53 with a high red content and green content, for example, a yellow daylight color, this is the case when one of the body colors 51, 52 has a higher green content and a lower red content than the other of the body colors 51, 52.

In a color copy according to the invention of a security feature according to the invention, it can be achieved that the first overlap region 13, the luminous region 3 and optionally the second overlap region 23 appear in the color copy as a unit region 4. A normal-sighted human eye can distinguish the luminous area 3 from the first overlap area 13 and the second overlap area 23 on an original security feature 8. Is this distinction by the Formation of the unit area 4 not possible, the color copy can be easily and quickly recognized as a forgery. Such a color copy is shown schematically in FIG Fig. 2 shown. By changing the settings of the color copier, the weighting of the colors can be changed, whereby the first overlapping area 13 and the second overlapping area 23 can be visualized. By changing the weight of the colors but also the reproduction of all other colors of the security document 9 is changed on the color copy, whereby the color copy acts unnatural and can also be easily and quickly recognized as a fake. In Fig. 3 is a color copy in which the cold colors are emphasized and in Fig. 4 a color copy in which the warm colors are emphasized, shown schematically. It has been shown that, given a sufficient distance of the two body colors 51, 52, even when changing the settings of the color copier, it is not possible to copy the first overlapping area 13, the second overlapping area 23 and the luminous area 3 such that these areas are for the human eye are distinguishable on the color copy.

Color blind persons, too, who can distinguish at least the first overlapping region 13 or the second overlapping region 23 from the luminous region 3, it being sufficient if they are perceived as different shades of gray, can distinguish a color copy from an original security document 9 by means of the security feature according to the invention.

Another advantage of the security feature 8 according to the invention is that, when using a daylight fluorescent ink 53, it represents another security feature due to its fluorescent properties. In this case, the fluorescence in the luminous area 3, in the first overlapping area 13 and in the second overlapping area 23 is excited to different degrees, so that an additional security feature is formed by the different intensity.

For the application of the body colors 51, 52 in particular the indirect high pressure or the wet offset printing and for the application of the printing ink 3 in particular the screen printing, gravure printing or flexographic printing seems to be suitable.

The advantages of the security feature 8 according to the invention also occur during printing after a previous scanning.

Claims (11)

1. A security feature (8) for security documents (9), especially bank notes, with a first body color (51) being applied in a first region (1) and a printing ink (53), especially a day luminescent dye, being applied in an illuminating region (3), with the printing ink (53) being applied outside the copy dye range of the four color print according to the Europe scale or DIN scale, characterized in that a first mixed color (54) of the first body color (51) and the printing ink (53) is applied in a first overlapping region (13), and that the first mixed color (54) is arranged outside of the copy dye range or in the boundary region of the copy dye range.
2. A security feature (8) according to claim 1, characterized in that the first overlapping region (13) is arranged adjacent to the first region (1) and adjacent to the illuminating region (3).
3. A security feature (8) according to claim 1 or 2, characterized in that the maximum of the reflection curve of the first mixed color (54) is higher than the maximum of the reflection curve of the first body color (51).
4. A security feature (8) according to one of the claims 1 to 3, characterized in that the intensity of the reflection curve of the first mixed color (54) at maximum is higher than 90%, preferably higher than 95%, more preferably higher than 100%.
5. A security feature (8) according to one of the claims 1 to 4, characterized in that in a second region (2) a second body color (52) is applied and that in a second overlapping region (23) a second mixed color (55) of the second body color (52) and the printing ink (53) is formed, and that the second mixed color (55) is situated outside of the copy dye range.
6. A security feature (8) according to claim 5, characterized in that the second overlapping region (23) is arranged adjacent to the second region (2) and adjacent to the illuminating region (3).
7. A security feature (8) according to claim 5 or 6, characterized in that the maximum of the reflection curve of the second mixed color (55) is higher than the maximum of the reflection curve of the second body color (52).
8. A security feature (8) according to one of the claims 5 to 7, characterized in that the intensity of the reflection curve of the second mixed color (55) at the maximum is higher than 90%, preferably higher than 95%, and more preferably higher than 100%.
9. A security feature (8) according to one of the claims 5 to 8, characterized in that one of the body colors (51, 52) has a higher share in a first primary color and a lower share in a second primary color than the other of the body colors (51, 52), with the percentage in the third primary color being smaller than the percentage of the first primary color and the second primary color in the printing ink (53) and with the first primary color, the second primary color and the third primary color being chosen from the quantity of the primary colors of red, green and blue.
10. A security feature (8) according to one of the claims 5 to 9, characterized in that the first body color (51) is substantially a complementary color of the second body color (52).
11. A security document (9), especially a bank note, comprising a security feature (8) according to one of the claims 1 to 10.

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