CA2743408C

CA2743408C - Security element having a machine-readable code

Info

Publication number: CA2743408C
Application number: CA2743408A
Authority: CA
Inventors: Peter Schiffmann; Daniela Otto; Juergen Zerbes; Harald Reiner; Karlheinz Mayer; Reinhard Plaschka; Norbert Holl; Marianne Neveling; Dieter Stein; Thorsten Pillo
Original assignee: Giesecke and Devrient GmbH
Current assignee: Giesecke and Devrient Currency Technology GmbH
Priority date: 2008-11-14
Filing date: 2009-10-29
Publication date: 2017-09-19
Anticipated expiration: 2029-10-29
Also published as: RU2011123483A; CA2743408A1; EP2356615B1; DE102008057320A1; EP2356615A1; WO2010054747A1; RU2527757C2

Abstract

The present invention relates to a security element (12) having a machine-readable code whose information content is not detectible with the naked eye and without auxiliary means, the code exhibiting a coarse code (22) having low information content for detection with a low-resolution sensor and, arranged within the coarse code (22), a fine code (24) having higher information content for detection with a high-resolution sensor of the same kind.

Description

Security Element Having a Machine-Readable Code The present invention relates to a security element having a machine-readable code, a method for manufacturing such a security element and a security paper and a data carrier having such a security element.
For protection, value documents, such as banknotes, stocks, bonds, certificates, vouchers, checks, valuable admission tickets and other security documents that are at risk of counterfeiting, such as passports, visas or other identification documents, are normally provided with security features that allow the authenticity of the document to be verified, and that simultaneously serve as protection against unauthorized reproduction.
The security features are often developed to be machine-readable to facilitate an automatic authenticity check and, if applicable, a further sensor-based detection and processing of the documents. One example of a machine-readable security feature for banknotes is a code based on infrared-visible and non-infrared-visible areal regions that are arranged on a banknote in the form of a specified code. A sensor of a banknote processing system is typically used for detecting such an infrared feature.
Based on that, the object of the present invention is to provide a generic security element having an improved machine-readable code.
This object is solved by the security element having the features of the main claim. A method for manufacturing such a security element, a security paper and a data carrier having such a security element are specified in the coordinated claims. Developments of the present invention are the subject of the dependent claims.

- 2 -According to the present invention, a generic security element includes a machine-readable code whose information content is not detectible with the naked eye and without auxiliary means, and that exhibits a coarse code having low information content for detection with a low-resolution sensor and, arranged within the coarse code, a fine code having higher information content for detection with a high-resolution sensor of the same kind.
What is essential here is that the coarse code and the fine code be designed for detection with sensors of the same kind that differ only in their resolution capability. Such a code facilitates, for machine readout, a smooth transition from existing machines having low-resolution sensors to improved machines having high-resolution sensors. The machines already installed in the field that include only a low-resolution sensor can continue to detect the coarse code portion of the code. Beyond that, however, the code includes, in its fine code portion, additional information that can be read with the high-resolution sensors of the improved machines. In this way, the improved machines can gradually replace the existing machines, since the coarse code can be read out both with the low-resolution and with the high-resolution sensors. The character of the coarse code, for example as an infrared feature or a magnet feature, does not change due to the added fine code, since the fine code is designed for detection by the same kind of sensors as for the coarse code.
In one advantageous variant of the present invention, it is provided that the code is designed for detection with infrared sensors, and the coarse code and the fine code are formed by regions including infrared-absorbent material.
The regions of the coarse code and of the fine code preferably include the same infrared-absorbent material. Here, the infrared sensors are preferably designed for detection in the spectral range between 800 urn and 1600 urn,

- 3 -especially between 800 nm and 1100 nm. The visible spectral range can be masked out by blocking filters.
According to a further, likewise advantageous variant of the present invention, the code is designed for detection with luminescence sensors, and the coarse code and the fine code are formed by regions including luminescent material. Here, the term luminescence comprises both fluorescence and phosphorescence, and both down conversion (excitation at higher radiant energy than the energy of luminous radiation) and up conversion (excitation at lower radiant energy than the energy of luminous radiation). The excitation can occur in the visible, infrared or ultraviolet spectral range. The intensity of the excitation and the required sensitivity of the sensor are chosen according to the luminescent substance(s) used. For afterglow-Mg substances (phosphorescent substances), the excitation can occur asynchronously for verification, with the time difference depending on the duration of the afterglow of the luminescent substance used. The regions of the coarse code and of the fine code preferably include the same luminescent material.
According to a further, likewise advantageous variant of the present invention, the code is designed for detection with magnet sensors, and the coarse code and the fine code are formed by regions including magnetic material. The magnetic regions can especially include hard and/ or soft iron and/or magnetic materials of differing coercive field strength. The regions of the coarse code and of the fine code preferably include the same magnetic material. Track-based magnet sensors in banknote processing systems typically exhibit between 3 and 200 tracks. In each track, the presence and/or the quantity of an ink provided with magnetic pigments on the banknote that is passed close by the sensor is checked.

- 4 -Of course the code can also be reali7ed by a combination of the cited variants.
In one preferred embodiment, the coarse code forms a 1-bit code. The fine code, in contrast, advantageously forms a code having an information content of at least 2 bits, especially a one-dimensional or two-dimensional barcode. A matrix code or pixel code are also conceivable variants of the fine code.
The fine code can be arranged in the border or corner region, or also in the interior of the coarse code. The coarse code can exhibit an arbitrary contour shape, with quadratic, rectangular, round, oval, honeycomb-shaped or polygonally delimited contour shapes being preferred at present.
To conceal the presence of a code when the security element is viewed visually, the coarse code and the fine code preferably exhibit the same color tone in the visible spectral range and appear transparent especially in the visible spectral range. The coarse code and the fine code can also be part of an image motif that is visible in the visible spectral range to further disguise the presence of an encoded piece of information.
In one preferred embodiment, the coarse code and the fine code constitute different pieces of information that are not related to one another. The information of the fine code can especially constitute a further authenticity feature and/or a logistics feature, as explained in greater detail below.
In one development of the present invention, the code, together with an ink that is substantially the same color tone in the visible spectral range, is developed as an infrared edging, as a luminescence edging or as a magnet edging.

- 5 -In preferred embodiments, it is provided that the code is multiply present on the security element. In this way, even if the security element becomes dirty, for example in the case of a banknote provided with the security element in which one of the codes is no longer readable error-free, another code that is still readable can be used.
The present invention also includes a method for manufacturing a security element of the kind described above in which is applied to a substrate a machine-readable code whose information content is not detectible with the naked eye and without auxiliary means, the code being developed having a coarse code having low information content and having, arranged within the coarse code, a fine code having higher information content.
Here, in an advantageous method variant, both the coarse code and the fine code are imprinted on the substrate in offset, screen, flexographic, gravure, inkjet, laser or intaglio printing. In another, particularly advantageous method variant, only the coarse code is imprinted on the substrate in offset, screen, flexographic, gravure, inkjet, laser or intaglio printing, and the fine code is produced by a laser marking of the coarse code. This method variant is suited especially for the combination of intaglio printing for the coarse code and laser marking to produce the fine code.
According to a further method variant, a marking layer is first applied to the substrate and the coarse code and the fine code are produced by a laser marking of the marking layer. The marking layer can especially be imprinted in offset, screen, flexographic, gravure, inkjet, laser or intaglio printing and can also comprise multiple sub-layers that can also be applied with various printing methods. The marking layer can take up the entire surface area of the security element and thus possibly the entire surface area of a security or

- 6 -value document provided with the security element. For example, an infrared absorber can be integrated into the ink-receiving layer of a polymer banknote such that the ink-receiving layer simultaneously forms the marking layer for the combination code.
If the combination code is manufactured in offset, screen, flexographic or gravure printing, then the code is normally printed in a pattern via at least two printing plates. If an ink that is not visually visible is used for the code, one printing plate is sufficient. To avoid any visual perceptibility, the printing preferably occurs joint to joint as an area. It is also conceivable to reali7e the printing as a tile pattern or rasterized in order to further impede the visual perceptibility. Further, inks that visually appear in the same color tone are advantageously used for the code and the printing of the surrounding region. If a tile pattern is used, the tile size preferably corresponds to the bit size of the fine code.
If the combination code is manufactured in inkjet or laser printing, then, as with the above-mentioned printing methods, two inks that are visually substantially the same color tone are printed. The appropriate special ink for the code is chosen via predefined print regions. In the case of visually non-visible code inks, this can be reali7ed particularly easily in combination with the primary colors yellow, red, cyan and black. Here, the visually non-visible code ink is applied through normal printing, which is possible, for example, with the aid of a special printer driver.
When producing the combination code in intaglio printing, only one printing plate is available. Using stencil plates, it is possible to ink this one printing plate differently in parts with up to five different individual inks. Since both the printing and the non-printing region are inked, the excess ink is wiped away by means of paper, a towel or a wiper cylinder such that, thereafter,

- 7 -only the lower-lying sites of the engraving exhibit ink. 'Through the wiping process, a mixing of the inks, and thus a slight dirtying, inevitably occurs in adjoining regions. The mixing zone can measure up to about 5 mm depending on the ink control and the rheology of the inks. Therefore, with .. pure intaglio printing technology, only relatively coarse codes are realizable.
Thus, to produce a combination code, advantageously, first the coarse code is produced in intaglio printing and the printing ink within the coarse code then ablated or modified locally by laser impingement to produce the high-.. resolution fine code within the coarse code.
Furthermore, the coarse and fine code can consist of one or more print region(s) that are produced through different printing methods. These regions can preferably include one or more infrared-absorbent materials.
.. This applies likewise for the magnetic and luminescent material.
The described security element can be formed by a standalone security element that is produced separately and then applied to a security paper or a value document. But the security element can also be produced directly on .. or in a security paper or value document, for example in that the code is imprinted on the security paper or the substrate of a value document.
The present invention also comprises a security paper for manufacturing security and value documents, such as banknotes, checks, identification .. cards, certificates or the like, having a security element of the kind described, and a data carrier having such a security element In both cases, the security element can first be produced separately and the finished security element then transferred to the security paper or value document, or the security element can be produced directly on or in the security paper or value .. document The data carrier can especially be a banknote, a value document,

- 8 -a passport, an identification or credit card, or a certificate. The security element, security paper or data carrier described can also be used for safeguarding articles of any kind.
Further exemplary embodiments and advantages of the present invention are described below with reference to the drawings. To improve clarity, a depiction to scale or proportion was dispensed with in the drawings.
Shown are:
Fig. 1 a schematic diagram of a banknote having a security element according to the present invention, Fig. 2 the distribution of the infrared-absorbent material in the code of the security element in fig. 1, Fig. 3 and 4 the appearance of the banknote in fig. 1 for a low-resolution and high-resolution infrared sensor, Fig. 5 to 7 banknotes having inventive security elements according to further exemplary embodiments of the present invention, Fig. 8 and 9 the appearance of the banknote in fig. 7 for a low-resolution and high-resolution infrared sensor, Fig. 10 a cross section through a banknote having an inventive security element according to a further exemplary embodiment of the present invention, Fig. 11 the visual appearance of the banknote in fig. 10, and

- 9 -Fig. 12 the appearance of the banknote in fig. 10 for a high-resolution infrared sensor.
The invention will now be explained using a banknote as an example. For this, fig. 1 shows a schematic diagram of a banknote 10 that is furnished with an inventive security element 12. The security element 12 includes a machine-readable code whose information content is not detectible with the naked eye and without auxiliary means and can be read out only with the aid of special sensors.
In addition to the code, the banknote 10 typically also exhibits visually perceptible color regions 14 that are responsible only for the visual appearance and do not appear for the special read-out sensors. In the visible spectral range, the visually perceptible color regions 14 and the code of the security element 12 normally exhibit a different color tone, as indicated by the differing hatchings in fig. 1. In advantageous embodiments, the code of the security element 12 is not perceptible in the visible spectral range and is, for example, transparent or kept in the same color tone as the surroundings 16 of the code or concealed in another print element.
In the exemplary embodiments described in greater detail below, the code of the security element 12 is designed for detection with infrared sensors.
However, it is also possible to design the code for detection with luminescence sensors or magnet sensors, as described above. With reference to the diagram in fig. 2, the code includes, for detection with infrared sensors, regions 20 having infrared absorbers that, in the infrared spectral range, stand out clearly from the infrared-reflecting surroundings.
Alternatively, the code can also be formed by infrared-reflecting regions in infrared-absorbent surroundings, as explained below.

- 10 -According to the present invention, the machine-readable code of the security element 12 includes a combination of a coarse code 22 having low information content, which is intended for detection with a low-resolution infrared sensor, and a fine code 24 arranged within the coarse code 22 having higher information content, which is intended for detection with a high-resolution infrared sensor. Such a combination code offers the advantage that already installed reading devices that include only a low-resolution infrared sensor can detect the coarse code portion 22 of the code, but at the same time, the possibility is created to read out and to utili7e the further information included in the fine code 24 with newer reading devices that already include a high-resolution infrared sensor.
Fig. 3 shows, schematically, the appearance of the banknote 10 for a low-resolution infrared sensor whose measurement field 30 is indicated by a frame. The banknote background and the visually perceptible color regions 14 exhibit a very similar infrared reflectivity and are thus not distinguishable for the infrared sensor, while the coarse code 22, due to the included infrared-absorbent material, stands out clearly from the banknote background.
The finer distribution of the infrared absorber in the fine code 24 is not resolved by the low-resolution infrared sensor such that the areal region of the fine code 24 within the coarse code 22 appears uniformly having an average infrared absorption, as shown in fig. 3.
In the exemplary embodiment, the coarse code 22 forms a 1-bit code (present/not present) and typically exhibits a minimum size of 12 x 12 mm2.
In addition to the shown quadratic shape of the coarse code region, also other contour shapes may be used, for example rectangular, round, oval, honeycomb-shaped, polygonally delimited or also irregular contour shapes.

- 11 -The border of the coarse code region can be sharp or softened, for example rasterized.
A quasi code can be reali7ed through the position of the coarse code 22 on the banknote 10. For example, the coarse code 22 can be arranged at different positions on the banknote for different denominations of an issue.
Fig. 4 now shows, schematically, the appearance of the banknote 10 for a high-resolution infrared sensor. Here, too, the banknote background and the visually perceptible color regions 14 are not distinguishable due to their similar infrared reflectivity. However, within the coarse code 22, the high-resolution infrared sensor can additionally resolve the finer distribution of the infrared absorber in the fine code 24 and thus read out its information content. In the exemplary embodiment shown, the fine code 24 constitutes a one-dimensional barcode, but also all other kinds of codes may be used.
Here, the fine code preferably forms a code having an information content of at least 2 bits. The size of the areal regions that each form one bit of the fine-coding code is significantly smaller than for the coarse code and is typically between about 2 x 2 mm2 and about 6 x 6 mm2, but smaller areal regions from about 0.5 x 0.5 mm2 may also be used. Here, too, areal regions other than quadratic ones may, of course, be used.
The coarse and fine code are preferably read out in the same wavelength range, and the infrared sensors used differ only in their resolution. Also the information in the coarse and that in the fine code does not depend on or complement one another, but rather, the coarse and fine code each constitute standalone codes. The further information of the fine code can especially be used as an authenticity feature or/and as a logistics feature.

- 12 -For example, a machine having low-resolution sensors can detect the presence of an infrared feature on a banknote via the position of the coarse code, while a machine having high-resolution sensors can detect a further characteristic feature, such as the issue date of the banknote. The fine code can also serve as an authenticity feature in that, for example, a certain group of numbers is coupled with a special code, for example a check digit The additional information of the fine code can be used to check the authenticity of the banknote even more accurately than is possible with the low-resolution sensor. The fine code can especially be linked with a further feature, such as the cited check digit or a magnetic feature. The counterfeit security of the security element having a combination code is higher compared with a security element that is furnished only with the coarse code, since a potential counterfeiter must discover and interpret the high-resolution additional code.
When used as a logistics feature, the fine code can be used, for example, to distinguish new or different substrate qualities, or when upgrading the banknotes with a new feature. This makes it possible, for example, to specifically obtain statements about the durability of new substrates, to specifically remove banknotes without the new feature from the market, or also to adjust the adaptation of the machine. A further possible use of the combination code consists in that the high-resolution sensor can detect a new feature given the otherwise nearly identical configuration of the banknote, and can automatically change the adaptation of the machine to specifically read a new feature, for example a magnetic feature, or to specifically gap the region of a new feature, which can be appropriate in the case of, for instance, features in the form of holographic patches or of a window region of the banknote.

- 13 -The coarse code 22 and the fine code 24 in fig. 2 exhibit, visually, the same color tone so as not to disrupt the design of the banknote 10 and to conceal the presence of a code from the user. Alternatively, for this purpose, the codes 22,24 can be non-visible in the visible spectral range, or visually display another form than the form of the codes 22, 24.
To read out the fine code 24, the banknote 10 is illuminated with a light source that emits at least in the IR range. A high-resolution infrared sensor includes, for example, a line or matrix camera. In the first case, a two-dimensionally resolved image can be produced through a movement of the banknote 10. Here, the resolution is determined by the number of pixels/unit length of the line camera, the speed of the transport of the banknote and the read-out speed of the line camera. The resolution of a matrix camera is determined by the number of pixels/surface area.
Both line and matrix cameras are preferably designed for detection in the range between 800 nm and 1600 urn, preferably between 800 nm and 1100 nm. The visible spectral range can be masked out by using a blocking filter.
For the high-resolution sensor, there also exists the possibility to create, through a precise location specification within the code, a reference area for the light/dark contrast to improve the image analysis, and thus also a better mapping of infrared-absorbent and non-infrared-absorbent regions.
A further exemplary embodiment of a banknote 10 having a machine-readable combination code 40 is depicted in fig. 5. The combination code 40 includes, like the code depicted in figures 1 to 4, a coarse code 42 and a fine code 44, with the fine code 44 in fig. 5 not being arranged in a border region, but rather in the interior of the coarse code 42.

- 14 -Also the machine-readable combination code 50 of the exemplary embodiment in fig. 6 includes a coarse code 52 and a fine code 54, the fine code 54 in this exemplary embodiment being grouped around the coarse code 52, and resulting from the four corners of the coarse code region.
Fig. 7 shows a further exemplary embodiment of the present invention, in which the machine-readable combination code 70 of the banknote 10 is part of an infrared edging 60. The infrared edging 60 consists of a color region 62 that is not visible in the infrared, and the combination code 70 that is visible in the infrared, the color region 62 and the combination code 70 exhibiting substantially the same color tone in the visible spectral range and being printed joint to joint. Visually, the infrared edging 60 thus appears as a uniform surface having an appearance as depicted in fig. 1.
The machine-readable combination code 70 includes a coarse code 72 and a fine code 74, the fine code 74 being arranged at the junction of the infrared edging 60.
A low-resolution infrared sensor cannot resolve the finer distribution of the infrared absorber in the fine code 74 and detects only the coarse code 72, as depicted in fig. 8. A high-resolution infrared sensor can resolve, in addition to the coarse code 72, also the fine code 74, such that the appearance depicted in fig. 9 results.
The combination code can also be formed by infrared-reflecting regions in infrared-absorbent surroundings, as will now be explained with reference to figures 10 to 12. Here, fig. 10 shows, schematically, a cross section through a banknote 10 having a machine-readable combination code 80, fig. 11 shows

- 15 -the visual appearance of the banknote 10, and fig. 12 the appearance for a high-resolution infrared sensor.
With reference first to fig. 10, the banknote 10 includes a marking layer 90 that consists of an infrared-absorbent background layer 92 imprinted on the banknote substrate 96 in offset printing, and an infrared-absorbent intaglio printing layer 94. Through laser impingement, the infrared absorption in the regions 82, 84 of the desired coarse and fine code was removed locally both in the background layer 92 and in the intaglio printing layer 94 such that the regions 82,84 form infrared-reflecting regions against an infrared-absorbent background.
The background layer 92 ensures a uniform infrared absorption of the areal regions of the marking layer 90 that are not impinged on with laser radiation. The removal of the infrared absorption can be based on, for example, a removal or a modification of the infrared absorbers included in the layers 92 and 94. In this method variant, the coarse code 82 and fine code 84 are produced together by the laser impingement of the marking layer 90.
The background and marking layer themselves can be patterned areally or as a pattern. Moreover, the same but also different IR absorbers can be used in the background and marking layer.
Fig. 11 shows the visual appearance of the banknote 10, in which neither the coarse nor the fine code appears. The marking layer 90 itself can especially be developed to be visually visible in the form of a desired motif, can be visually non-visible, or can be visually visible, but concealed in another printing element.

- 16 -Fig. 12 shows the appearance of the banknote 10 for a high-resolution infrared sensor for which both the coarse code 82 and the fine code 84 is perceptible. If, in contrast, the combination code 80 is detected with a low-resolution infrared sensor (not shown), then only the coarse code 82 is perceptible, while the fine code 84 is not resolved.

Claims

Claims The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method for manufacturing a security element having a machine-readable code whose information content is not detectible with the naked eye and without auxiliary means, the code exhibiting a coarse code having low information content for detection with a low-resolution sensor and, arranged within the coarse code, a fine code having higher information content for detection with a high-resolution sensor of the same kind, the method comprising a step of applying to a substrate a machine-readable code whose information content is not detectible with the naked eye and without auxiliary means, the code being developed having a coarse code having low information content and having a fine code having higher information content arranged within the coarse code, by imprinting the coarse code on the substrate in intaglio printing, and producing the fine code by a laser marking of the coarse code.

2. The method according to claim 1, characterized in that the code is designed for detection with infrared sensors, and the coarse code and the fine code are formed by regions including infrared-absorbent material.

3. The method according to claim 1, characterized in that the code is designed for detection with magnet sensors, and the coarse code and the fine code are formed by regions including magnetic material.

4. The method according to claim 1, characterized in that the code is designed for detection with luminescence sensors, and the coarse code and the fine code are formed by regions including luminescent material.

5. The method according to any one of claims 1 to 4, characterized in that the coarse code forms a 1-bit code, or that the fine code forms a code having an information content of at least 2 bits.

6. The method according to any one of claims 1 to 5, characterized in that the fine code forms a one-dimensional or two-dimensional barcode.

7. The method according to any one of claims 1 to 6, characterized in that the fine code is arranged in the border or corner region of the coarse code.

8. The method according to any one of claims 1 to 6, characterized in that the fine code is arranged in the interior of the coarse code.

9. The method according to any one of claims 1 to 7, characterized in that the coarse code exhibits a quadratic, rectangular, round, oval, honeycomb-shaped or polygonally delimited contour shape.

10. The method according to any one of claims 1 to 9, characterized in that the coarse code and the fine code exhibit the same color tone in the visible spectral range, especially both appear transparent or white in the visible spectral range.

11. The method according to any one of claims 1 to 10, characterized in that the coarse code and the fine code are part of an image motif that is visible in the visible spectral range.

12. The method according to any one of claims 1 to 11, characterized in that the coarse code and the fine code depict different kinds of information.

13. The method according to any one of claims 1 to 12, characterized in that the code, together with an ink that is substantially the same color tone in the visible spectral range, is developed as an infrared edging, as a luminescence edging or as a magnet edging.

14. The method according to any one of claims 1 to 13, characterized in that the code is multiply present on the security element.

15. A security paper for manufacturing security and value documents, having a security element that is manufacturable according to any one of claims 1 to 14.

16. A data carrier having a security element that is manufacturable according to any one of claims 1 to 14.