EP1494874B1 - Security element - Google Patents

Abstract

The invention relates to a bar code which is integrated into the paper in the form of a watermark. The fields (6) separating the information-providing bars of the bar code are configured as watermarks. The information-providing bars can but do not necessarily have to be configured as watermarks. Their breadth is the result of the distance between the separating fields (6). The separating fields (6) are narrower than the information-providing bars, thereby keeping the entire length of the bar code short.

Description

The invention relates to a security element, namely a bar code in the form of a watermark, as well as a security paper and a value or security document produced therefrom, such as banknote, check, share, identity card, ticket, ticket, with such a bar code and furthermore a method and a paper strainer for making the security paper.

It is known to introduce a barcode - also called a barcode - in the manner of a watermark in paper, in particular in security paper, for the production of security or value documents. For example, the authenticity of banknotes can be checked on the basis of the bar code, if all banknotes of a certain value and a given issue date carry a certain watermark in the same way. By comparing with the serial number and denomination printed on the banknote, the authenticity of the banknote can then be checked by means of the bar code. Depending on the complexity of the information encoded in the watermark bar code, the bar code may become comparatively long, which is undesirable in small-sized securities such as banknotes.

But the problem is not only the length of the bar code, but in particular its verifiability for purposes of authentication. Because the wider the bars introduced into the paper as watermarks, the more uneven their appearance is when viewed through transmitted light. This is because a watermark with a uniformly dark surface is very difficult to realize. For the production of the watermark, the paper screen is embossed in order to influence the deposition of the paper fibers during sheet formation. If the screen is deeply embossed, more paper mass accumulates in this area, while an embossing deposits hampered by pulp. In an embossed area, especially the edges of the area form well. The surface itself either becomes lighter or darker inside.

A security paper having the features in the preamble of claim 1 is known from the document DE-A-3 034 916 known.

The object of the present invention is to provide a security paper equipped with a bar code in the form of a watermark, which is more versatile and comparatively space-saving, and a security or security document produced therefrom, as well as a method and a paper screen for producing the security paper.

These objects are achieved by a security paper, a security document, a method and a paper wire according to the independent claims. In dependent claims advantageous embodiments and developments of the invention are given.

Accordingly, the separating fields, by which the information-conveying bars are separated from each other, are formed as uniquely detectable watermarks. These separation fields are then detected by the bar code reader as a (separation field) bar. However, the actual bar code information is not determined by the width of the detected (separator field) bars but by the width of the fields lying between the detected (separator field) bars, these fields representing the actual bars of the bar code. That is, the separator bars each mark the beginning and the end of the information-conveying bars.

This offers the following two significant advantages over the prior art. First, the information-conveying bars of the bar code lying between the separating fields can be chosen as wide as desired become. Since the brightness of the information-conveying bars themselves is not included in the evaluation, there are no problems with an unevenly filled dark or light bar area in the transmitted light. Second, the separation fields can be made particularly narrow, in particular by using electrotypes on the paper wire, whereby the total length of the bar code is comparatively short and space-saving.

In order to further reduce the length of the bar code, it is advantageous to construct the bar code as a two-dimensional bar code comprising a plurality of e.g. has parallel tracks of information.

A particularly advantageous embodiment of the invention provides that the lying between the separating fields, the actual information-conveying bar of the bar code forming fields are not designed as watermarks, so that in the transmitted light alone the separation fields are recognizable as watermark bars. The first and last separator fields limit the bar code.

To increase the contrast, the information-conveying bars of the bar code can also be embodied as watermarks, with the separating fields being in the form of bright watermarks and the information-conveying bars as dark watermarks - or vice versa. It is preferable in this respect not to design the information-conveying bars but the separating fields as bright watermarks, since otherwise there would be a danger of hole formation in the paper in the case of light information-conveying bars with increasing bar width.

According to a particular embodiment of the invention defines an edge-side, that is first or last, separation field of the bar code, for example due to its characteristic width or fiber density, the information content attributable to beams of different widths, ie whether a broad bar indicates a "1" and a narrow bar indicates a "0" or vice versa. Alternatively, the first bar may be defined as a start bit and its width may indicate whether a wide bar of the bar code indicates a "1" and a narrow bar indicates a "0" or vice versa.

According to a preferred embodiment, a security or value document according to the invention is provided with an additional storage medium. This may, for example, be a magnetic storage medium, such as a magnetic track, or an electronic storage medium, such as an integrated circuit microchip. In such an embodiment, the bar code may also contain data for encrypting or decrypting information rather than the value of a document. The document value reproduced by the bar code can then advantageously be stored in the storage medium together with the serial number of the document or, for example, the result of a predetermined link between the value number and the serial number. This increases the security against forgery and the verifiability of the authenticity of a document. The storage of the linkage in the additional storage medium can be done during the production or the publication of the document. In an authenticity check, the result of the link can be read from the storage medium. If the type of linking is known, the serial number can be reconstructed together with the value of the document, which is particularly easy to extract from the barcode watermark. In addition, if the serial number is read directly from the document, there is an additional possibility for checking whether a read-out storage medium actually belongs to an individual document, such as a banknote.

In addition, one can use randomness in the formation of the barcode according to the invention, such as the cloudiness of the paper in the barcode area or irregularities in the edge profile of individual sections, as an additional reading in order to increase the security against counterfeiting of a document or to improve the authenticity check.

Figur 1

eine Banknote mit einem erfindungsgemäßen Wasserzeichenbalkencode,

Figur 2

eine Durchlichtansicht eines erfindungsgemäßen Wasserzeichenbalkencodes,

Figur 3

eine Durchlichtansicht eines weiteren erfindungsgemäßen Wasserzeichenbalkencodes,

Figur 4

ein Papiersieb schematisch im Querschnitt,

Figur 5

eine Durchlichtintensitätskurve gemäß einer ersten Ausführungsform eines erfindungsgemäßen Wasserzeichenbalkencodes,

Figur 6

eine Durchlichtintensitätskurve gemäß einer zweiten Ausführungsform eines erfindungsgemäßen Wasserzeichenbalkencodes,

Figur 7

eine Durchlichtintensitätskurve gemäß einer dritten Ausführungsform eines erfindungsgemäßen Wasserzeichenbalkencodes,

Figur 8

eine Durchlichtansicht eines Wasserzeichenbalkencodes gemäß dem Stand der Technik,

Figur 9

eine Durchlichtintensitätskurve zu einem Wasserzeichenbalkencode gemäß dem Stand der Technik, und

Figur 10

eine Durchlichtintensitätskurve zu einem Wasserzeichenbalkencode gemäß einem weiteren Stand der Technik.

The invention will now be described by way of example with reference to the accompanying drawings. Show:

FIG. 1

a banknote with a watermark bar code according to the invention,

FIG. 2

a transmitted light view of a watermark bar code according to the invention,

FIG. 3

a transmitted light view of another watermark bar code according to the invention,

FIG. 4

a paper screen schematically in cross-section,

FIG. 5

a transmitted light intensity curve according to a first embodiment of a watermark bar code according to the invention,

FIG. 6

a transmitted light intensity curve according to a second embodiment of a watermark bar code according to the invention,

FIG. 7

a transmitted light intensity curve according to a third embodiment of a watermark bar code according to the invention,

FIG. 8

a transmitted light view of a watermark bar code according to the prior art,

FIG. 9

a transmitted light intensity curve to a watermark bar code according to the prior art, and

FIG. 10

a transmitted light intensity curve to a watermark bar code according to another prior art.

FIG. 1 shows an example of one of many possible securities and security documents, a banknote 1 with the denomination 2 of "EUR 100". The banknote 1 has a two-dimensional bar code 3, which is integrated in the manner of a watermark into the security paper from which the banknote 1 is made.

Securities with a one-dimensional barcode in the form of a watermark are already known from the prior art. The wider the bars introduced into the paper as watermarks, the more uneven their appearance in transmitted light, so that the evaluation of the bars is very problematic. This is illustrated in FIG. 8, which schematically shows a watermark bar code 3 viewed in transmitted light. The bar code 3 was produced with an embossed paper screen, which promotes the accumulation of paper fibers in its embossed, the bars 5 of the bar code 3 generating areas. However, the fiber density, ie the paper thickness, decreases towards the interior of the beam surfaces so that, although the edge of the surface can be well imaged, the surface inside in transmitted light, on the other hand, appears lighter again. This is shown graphically in FIG. 9, where the transmitted light intensity I ⁺ , I ^- deviating from a normal transmitted light intensity I ₀ is plotted. It can be seen that the transmitted light intensity I in the center the bar is the closer to the normal transmitted light intensity I ₀ , the wider the bar is. It should be noted that the normal transmitted light intensity value I _{0 is shown} in Figure 9 idealized. In fact, this value I ₀ fluctuates around a mean value, so that it can occur with wide bars that a bar code sensor signals the end of a bar 5 or the beginning of a separating field 6, although only the middle of the bar 5 is reached. This can lead to read errors by mistaking a broad bar 5 as two short bars.

The alternative of using a light bar code instead of a dark bar code has the same drawback that the fiber density decreases towards the center of the bar. Again, there is no uniformly bright bar with the desired extent. Rather, there is a risk of hole formation in the paper with wide beams.

In Figure 10, the transparency I is for one of the DE 30 34 916 A1 represented known bar code, in which the above-described problem does not occur. Thus, the areas of the papermaking screen for forming the bars of the bar code are marked as rectangular, non-isosceles triangles in the papermaking screen. The portion of the watermark generated by the steep edge in the paper is readily recognizable in transmitted light as a pronounced dark or light stripe and marks the beginning of a bar 5. Whether the bar 5 represents a "1" or "0" does not depend on it Width but on whether the bar is light or dark, that is, whether the embossment of the paper strainer from the paper plane is directed up or down. As a result, the length of the entire bar code can be kept low because separation fields 6 between the individual bars 5 can be omitted to their unique, mutual demarcation. However, it is disadvantageous that the bar code is based on digital coding is limited, because only between light and dark fields is distinguished.

FIGS. 2 and 3 each show a detail of different embodiments of a watermark bar code 3 from FIG. 1 according to line AA when viewed in transmitted light. In both cases, and also in the example cases explained below, this is a digital bar code consisting of zeros and ones, where the bar width indicates the value "0" or "1". The bars 5 are separated from each other by separating fields 6, the first and the last separating field delimiting the bar code. The bar code shown in FIGS. 2 and 3 is thus 0-1-1-0 in each case.

In the embodiment according to FIG. 2, the separating fields 6 appear dark in comparison to the bars 5. That is, in the regions of the separating fields 6, the banknote has an increased fiber density, which was produced by a corresponding embossing of the paper screen used to produce the banknote paper. This paper screen embossing causes an increased paper fiber accumulation during the paper formation, whereby the transmitted light intensity is correspondingly reduced when viewing the paper in the transmitted light and the separating fields 6 appear dark. The bars 5, which define the actual information of the barcode, appear neither brighter nor darker in transmitted light than the banknote material surrounding the barcode, because the bars 5 have no watermark characteristic. Since, due to this fact, not the information-conveying bars 5 but the separating fields 6 are detected by means of a bar code reader, the width of the information-conveying bars is determined only indirectly via the distance between the detected separating fields 6.

The same applies to the embodiment shown in Figure 3, in which, however, departing from the embodiment of Figure 2, the separation fields 6 of the bar code appear bright, except for the leftmost separation field. The bright separation fields 6 can be generated particularly conspicuous by using so-called electric types. Electro types are typically small pieces of metal fixedly secured to one side of the papermaking screen, for example by soldering or by means of tabs inserted and bent into the meshes of the screen. This makes it possible to achieve very narrow and particularly bright transmitted light effects, which are easy to detect by sensors.

The outer left separation field 6 in FIG. 3 defines that the following broad bars are to be regarded as "0" and the narrow bars 5 as "1", as is also the case in FIG. If the outer left separation field 6 as the other separation fields 6 formed as a bright separation field, the information content of the bar 5 would be reversed and the total information of the bar code was not 0-1-1-0 but 1-0-0-1.

Instead of the characteristic transmitted light intensity or fiber density of the outer left separation field 6 - it could also be the outer right separation field 6 - also the width of the separation field can be used to indicate the information content of the wide and narrow bars 5. Both options can also be combined, in particular to define further information of the barcode.

Alternatively or additionally, the first or last bar 5 can also serve as a start bit or end bit, wherein, for example, the width of the start bit or end bit bar provides information as to whether the wide bars are to be regarded as "0" and the narrow bars as "1" are or vice versa.

FIG. 4 shows by way of example and only schematically a section of a paper screen 8 with which a paper with a watermark barcode according to FIG. 3 can be produced. The paper screen 8 has correspondingly spaced electrotypes 7 on its paper-forming surface for generating the bright separation fields 6 and a deep embossed area 9 for generating the outer left separator panel 6, which has an increased paper thickness or fiber density and therefore dark in transmitted light.

FIG. 5 shows an idealized transmitted light intensity profile of a bar code similar to the bar code shown in FIG. 2 with dark separating fields 6 and information-conveying bars 5. The transmitted light intensity I in the regions of the separating fields 6 lies below a normal transmitted light intensity I _{0 of} the banknote paper, since the fiber density F in the areas of the separating fields 6 is correspondingly high. The transmitted light intensity curve I thus coincides with the fiber density curve F when the intensity increase I ⁺ is applied upward and the fiber density increase F ⁺ is applied downward. The transmitted light intensity curve and the fiber density curve are therefore designated together with the reference numeral 4.

FIG. 6 shows the transmitted light intensity and fiber density curve 4 for a bar code similar to the bar code shown in FIG. In this case, the transmitted light intensities I in the regions of the separating fields 6 are above the normal transmitted light intensity I ₀ , apart from the outer left separating field 6, in which the transmitted light intensity I is below the normal transmitted light intensity I ₀ . In contrast to the representation according to FIG. 5, the transmitted-light intensity curve in FIG. 6 is illustrated in a less idealized manner, by showing that the transmitted light intensity or fiber density, despite its generally uniform distribution I ₀ , Fo, over the extent the bar 5 of the bar code fluctuates slightly by an average value I ₀ or Fo, which indicates the "normal transmitted light intensity" and "general fiber density".

FIG. 7 shows a further embodiment of the invention. This is essentially a combination of the prior art according to FIG. 9 and the embodiment according to FIG. 6 or FIG. 3. That is, both the separating fields 6 and the bars 5 are integrated in the paper in the manner of a watermark, wherein the Information-conveying bar 5 in transmitted light as dark areas with the initially described as disadvantageously described, slightly brighter centers and the separation fields 6 as easily identifiable, pronounced bright lines. The particularly high transmitted light intensity in the regions of the separating fields 6 exceeds the transmitted light intensity in the lighter, central regions of the information-conveying bars 5 such that a misinterpretation, as explained above, can be excluded. Compared with the embodiments according to FIGS. 5 and 6 or 2 and 3, the embodiment according to FIG. 7 offers an additional increase in contrast between the areas of the bars 5 and the separating fields 6 and thus improved readability of the bar code.

Claims (25)

1. A security paper with a general fiber density (F₀) for manufacturing a document of value or security document, as for example bank note, check, share certificate, identity card, ticket for public transport, admission ticket, comprising a bar code (3) consisting of information-conveying bars (5) separated from each other by separating fields (6), characterized in that the separating fields (6) are incorporated as a watermark in the security paper, so that the fiber density (F) of the security paper in the areas of these separating fields (6) deviates from the general fiber density (F₀).
2. The security paper according to claim 1, wherein the fiber density (F) of the security paper in the areas of the information-conveying bars (5) deviates in a different positive or negative direction from the general fiber density (F₀) as compared to the areas of the separating fields (6).
3. The security paper according to claim 2, wherein the fiber density (F) of the security paper in the areas of the information-conveying bars (5) is higher and in the areas of the separating fields (6) lower than the general fiber density (F₀).
4. The security paper according to claim 1, wherein the fiber density (F) of the security paper in the areas of the information-conveying bars (5) corresponds to the general fiber density (F₀).
5. The security paper according to any of claims 1 to 4, wherein the separating fields (6) are more narrow than the information-conveying bars (5).
6. The security paper according to any of claims 1 to 5, wherein the security paper when viewed in transmitted light at least in one of the separating fields (6) appears lighter than in an area of the security paper having the general fiber density (F₀), and at least in one of the other separating fields (6) appears darker than in an area of the security paper having the general fiber density (F₀).
7. The security paper according to any of claims 1 to 6, wherein an information-conveying bar (5) located at the boundary of the bar code (3) has a characteristic property as to indicate which information content ("0", "1") is assigned to each of the various bars (5) of different width of the bar code (3).
8. The security paper according to claim 7, wherein the characteristic property is the width and/or fiber density of the bar located at the boundary.
9. The security paper according to any of claims 1 to 8, wherein the bar code (3) is a two-dimensional bar code.
10. The security paper according to any of claims 1 to 9, characterized in that it has an additional storage medium, such as for example an area for magnetically storing information or a microchip.
11. A security document or document of value (1) comprising a security paper according to any of claims 1 to 9.
12. The security document or document of value according to claim 11, selected from the group of documents: bank note, check, share certificate, identity card, ticket for public transport, admission ticket.
13. The security document or document of value according to any of claims 11 or 12, characterized in that the document has an additional storage medium, such as for example an area for magnetically storing information or a microchip.
14. A method for manufacturing a security paper having a general fiber density (F₀) for a security document or document of value (1), such as for example bank note, check, share certificate, identity card, ticket for public transport, admission ticket, with a bar code (3) consisting of information-conveying bars (5) separated from each other by separating fields (6), wherein the security paper in the areas of the separating fields (6) is produced as a watermark with a fiber density (F₀) deviating from the general fiber density (F⁺,F^-).
15. The method according to claim 14 using a papermaking screen (8), which in the areas of the separating fields (6) is formed in a special way, so that in such areas the deposit of fibers for producing a watermark in the security paper to be manufactured is influenced positively or negatively.
16. The method according to claim 15, wherein the papermaking screen (8) in the areas of the information-conveying bars (5) is formed such that in these areas the deposit of fibers is influenced neither positively nor negatively.
17. The method according to claim 15, wherein the papermaking screen (8) in the areas of the information-conveying bars (5) is embossed such that the deposit of fibers in these areas is influenced positively.
18. The method according to any of claims 14 to 16, wherein the papermaking screen (8) at least in the area (9) of one of the separating fields (6) is embossed such that the deposit of fibers is influenced positively.
19. The method according to any of claims 14 to 18, wherein the papermaking screen (8) at least in the area of one of the separating fields (6) is provided with an electrotype (7), so that the deposit of fibers is influenced negatively.
20. A papermaking screen (8) for manufacturing a security paper with a bar code (3) consisting of information-conveying bars (5) separated from each other by separating fields (6), wherein the papermaking screen (8) has areas for producing the separating fields (6) where the papermaking screen is especially formed so as to positively or negatively influence the deposit of fibers in these areas for producing a watermark in a paper to be manufactured with the papermaking screen.
21. The papermaking screen according to claim 20, wherein the papermaking screen in its areas producing the information-conveying bars (5) is formed such that in these areas the deposit of fibers is not especially influenced and a watermark is not produced in a paper to be manufactured with the papermaking screen.
22. The papermaking screen according to claim 20, wherein the papermaking screen in its areas producing the information-conveying bars (5) is embossed so as to positively influence the deposit of fibers in these areas for producing a watermark in a paper to be manufactured with the papermaking screen.
23. The papermaking screen according to claim 20 or 21, wherein the papermaking screen is embossed (9) in at least one of its areas producing the separating fields (6), so as to positively influence the deposit of fibers for producing a watermark in a paper to be manufactured with the papermaking screen.
24. The papermaking screen according to any of claims 20 to 23, wherein the papermaking screen at least in one of its areas producing the separating fields (6) is equipped with an electrotype (7), so as to negatively influence the deposit of fibers for producing a watermark in a paper to be manufactured with the papermaking screen.
25. The papermaking screen according to any of claims 20 to 24, wherein the areas of the papermaking screen for producing the separating fields (6) are formed more narrow than those areas of the papermaking screen for producing the information-conveying bars (5).

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