WO2008006459A1

WO2008006459A1 - Method for applying a security feature to a security document, and security document comprising a security feature

Info

Publication number: WO2008006459A1
Application number: PCT/EP2007/005590
Authority: WO
Inventors: Steffen Noehte
Original assignee: Tesa Scribos Gmbh
Priority date: 2006-07-12
Filing date: 2007-06-25
Publication date: 2008-01-17
Also published as: DE102006032234A1

Abstract

The invention relates to a method for applying a security feature to a security document, said security document comprising a carrier layer provided with at least one recess and a transparent window film covering at least the recess. According to said method, at least one individual feature of the security document is determined, the security feature is produced on the basis of the at least one individual feature of the security document, and the security feature is connected to the window film in the region of the recess. The inventive method enables the technical problem of improving the forgery-proof characteristics of security documents to be solved. The invention also relates to a security document comprising a security feature.

Description

Method for applying a security feature to a security document and security document having a security feature

The invention relates to a method for applying a security feature on a security document, in particular on a banknote, wherein the security document has a carrier layer with at least one recess and a transparent window foil covering at least the recess. Likewise, the invention relates to a security document, in particular a banknote with a security feature.

A security document in the context of this description is understood to be any document that is to be protected against counterfeiting in a special way. In this case, a security document is understood in particular to be a banknote, a passport, a check card, an admission ticket or a label. Likewise under a security document seals and seals are understood. The term document is therefore not bound to a paper form and therefore to be understood generally. In particular, the term security document is also not to be understood as a written document.

The forgery-proof security documents, in particular banknotes, are becoming increasingly demanding. In addition, numerous security features have been developed in recent years and in Security documents have been added. For example, shiny metallic strips with printed dot matrix holograms have been banknotes in addition to the long used serial numbers and watermarks. In addition, markings are used on security documents that only become visible when illuminated with ultraviolet light.

In order to further increase the security against counterfeiting, for example, banknotes and other security documents are known which have at least one transparent window section. This can be avoided in a simple manner that the banknotes can be forged by becoming increasingly good copier. The transparent window sections have previously been used to display directly visible information such as numbers, fonts or pictures. These therefore represent Level-1 security features that are accessible to direct observation by a person without resources. In addition, these are characteristics that are identical for all banknotes of the same value. The provision of window cut-outs is possible not only with banknotes but also with other security documents.

Security features are known from the prior art, which consist of microstructures, which are designed in particular as computer-generated holograms. Microstructures consist of one or more layers of Punktematrizen or point distributions, which in the case of a computer-generated hologram when illuminated with a preferably coherent light beam to a Reconstruct the encoded in the hologram information. The point distribution can be calculated as an amplitude hologram, phase hologram or as a kinoform, Fourier or Fresnel hologram. For the production of computer-generated holograms, these are first calculated and then written with a suitable writing device by point-wise introduction of energy into a storage medium.

The resolution of the microstructuring, ie the dot matrix, can be in the range below 1 μm. Thus, holograms, microimages or micro-scripts can be written in a small space with a high resolution, the information of which can only be read out by illuminating with a light beam and reconstructing the diffraction image or by magnification on direct viewing. The size of the microstructures can be between less than 1 mm ² and several 5 cm ² .

The computer-generated holograms described above can be combined with directly visible information, for example with a micro-typeface, with a microimage and / or with coded information such as a barcode.

Furthermore, a plurality of writing devices for writing microstructures, in particular computer-generated holograms, which write the optical-active structures in planar storage media, are known from the prior art. Exemplary will be on the References WO 02/079881, WO 02/079883, WO 02/084404, WO 02/084405 and WO 03/012549. Such writing devices are also referred to as laser lithographs or as lithographic systems.

Likewise, a plurality of reading devices are known, which are suitable for illuminating the hologram surface by means of a light beam and a suitable optical system, rendering the reconstruction visible or electronically representable and evaluable by means of recording means. Likewise, reading devices are known in which the direct observation of the microstructuring for detecting microimages and microfonts is possible. By way of example, reference is made to the publications DE 101 37 832, WO 02/084588 and WO 2005/111913.

Visible light diffractive or at least influencing microstructures are therefore widely known and are - as already stated - used as security features. For their counterfeiting a considerable technical effort is required, since the structure sizes are in the range of optical wavelengths. Such microstructures are usually realized as reflective structures. However, they can also be realized as a transmittively observable / readable structure.

The invention is based on the technical problem of specifying a method for applying a security feature to a security document as well as a security document having a security feature, by means of which improved security against counterfeiting is achieved. In particular, the invention is based on the technical problem of generating a further individual security feature that is generated from at least one individual information that is generated or printed therein during the production of a security document and to connect it to the security document.

Another technical problem of the present invention is to decouple technically complex steps for introducing security features from the actual manufacturing process of the security documents.

The above-mentioned technical problems are inventively at least partially solved by a method for applying a security feature on a security document, in particular on a banknote with the features of claim 1.

The inventive method for applying a security feature on a security document, in particular on a banknote, assumes that the security document has a carrier layer with at least one recess and a transparent window foil covering at least the recess. In a first step, at least one individual feature of the security document "is determined and the security feature is generated based on the at least one individual feature of the security document." In a second step, the security feature in the region of the recess is connected to the window film. As the backing layer of the security document, all suitable papers, fabrics and plastics come into question, as they have also been used in the prior art.

The preparation of the security document per se can therefore be completed before the additional security ^{feature is} created and connected to the security document. Thus, in an advantageous manner, individual features of the security document that are generated at different points in time in the production process can in some cases even only at the end of the

Manufacturing process, combined together and processed into an additional new security feature. For example, the serial number of a banknote, which is only printed during the final printing process with the banknote, namely printed, can be used to generate the security feature to be connected to the window film. If, in addition to the serial number, at least one further individual feature of the banknote is present, the at least two individual features can be linked to one another.

The process of generating the additional security feature is thus decoupled from the actual production of the security document. Therefore, the security feature can also be connected to it with a longer time interval for the production of the security document. Thus, in the production of security documents, first of all quality and Security requirements are checked. This happens, for example, in banknotes in specially designed sorting systems that sort out defective productions. During the check, in addition to the serial number, other security features of the bank note are recorded, which are then stored as a data record in a computer system. These individual data records, which are individual for each banknote, can then be used at a later time for the calculation of the security feature.

Alternatively, the method according to the invention can also be carried out in such a way that information already stored is not used, but that the individual features of each security document are recorded separately for the calculation of the security feature.

The method according to the invention described above is therefore also particularly advantageously suitable for switching off a security document independently of the time of manufacture by the separate application of an individual security feature. In this way, in particular in the production of banknotes, costly measures for securing the banknotes can be reduced in that the banknotes can be completed and thus activated only shortly before their delivery by the application of the individual security feature.

Preferably, the security feature is inscribed in a storage film, which is then connected to the window film. This makes it possible in an advantageous manner, the security feature separately from the security document and then connect to the security document. In particular, in the preferred microstructures described below results in the advantage that the production of the

Security feature associated high accuracy requirements during exposure better separate from the security document can be met, as it is the case for example, if the Fenεterfolie would be described directly.

Preferably, the storage film is applied so that it is arranged overlapping the recess. This ensures that the edge of the recess is completely covered not only on the side of the window film, but also on the side of the storage film, whereby mechanical damage to the edge of the recess and thus damage to the security document, in particular a banknote itself is prevented ,

Furthermore, the storage film in the region of the recess can at least partially be glued to the window film. This not only creates an intimate contact between the storage film and window film as a composite structure, but also interfaces are avoided, which would arise between the window film and the storage film, if there would be air between them. In addition, surface roughnesses can be compensated if a suitable adhesive is used for the connection between the storage foil and the window foil. This allows the reading of the security feature in Transmission can be significantly improved because scattering effects are reduced.

In addition, effective protection of the holographic structure is given because the composite structure always places a protective layer over the hologram. This also means that the microstructures do not necessarily have to be written into the functional layer by a carrier film, but can also be written directly to the surface.

If the storage film covers the recess, it is of course advantageous if the storage film is also adhesively bonded to the carrier layer of the security document.

In a further preferred manner, the storage film is applied to the security document on the side facing away from the window film. Moreover, if the storage film has the same dimensions as the window foil, then the forces exerted by the window foil and the storage foil on the carrier layer of the security document compensate each other and a curvature or sagging of the security document can be effectively avoided.

A further embodiment of the present invention is that the storage film is applied with smaller dimensions as the window film. In this case, the storage sheet is overlapped within the recess and not overlapped with the support layer. Thus, there is only contact between the storage foil and the window foil, while the Storage film is not connected to the support layer of the security document or has a contact. This embodiment has the advantage that the storage film can be connected to the window film, without the need for any necessary bending or bending at the edge of the recess. This can improve the read quality of the security feature. In addition, it avoids that the document is applied or fanned out by the composite structure too much. This has advantages, especially in stacking.

Previously, the invention has been described in that the security feature is written in a separate memory sheet. This of course means an additional technical effort. In the context of the invention, it is also possible that the security feature is written directly into the window film. In this case, the storage film can be avoided, with only care must be taken to ensure that the window film is aligned flat in writing to the writing device. However, if the writing process is carried out in each case with new security documents, in particular banknotes, kinks or other unevenness of the window film are unlikely, which could adversely affect the writing process.

Another aspect of the present invention relates to determining the at least one individual feature of the security document. The first variant is that the at least one individual feature of the bill is read directly from the security document. This is a method for Completing the security feature completely decoupled from the production of the security documents themselves. Although a reading device for detecting the at least one individual feature is required for this purpose, however, the security feature can be applied to the security documents completely independently of the manufacturing process, ie both temporally and spatially separated.

Alternatively, the at least one individual feature of the security document can be read from a data store in which data of the features found in the sorting system, in particular the individual features, have been written after the security document has been produced. This eliminates a separate determination of the individual features of the security document and the data obtained during the manufacture and sorting of the newly manufactured security documents are used directly for further identification with an additional security feature.

In a preferred manner, when carrying out the method according to the invention, the security feature is written into the memory film or the window film with the aid of a laser lithograph. Thus, the already proven technique for creating microstructures can be used for the individualized identification of security documents with security features.

In the microstructuring of the security feature, which has been connected to the security document can Both level-1 features, ie in directly visible structures, as well as level-2 or level-3 features can be included, which can be read only with the help of an additional device. The Level 2 and Level 3 features include in particular the computer generated holograms already mentioned above as diffractive structures.

Since both the storage film and the window film are at least partially transparent, the security features can have properties that can be detected either in transmission or in reflection.

Therefore, in a particularly preferred manner in at least one functional layer of the storage film, at least one feature observable in reflection and in the at least one functional layer of the storage film at least one feature observable in transmission can be written. At least one feature is individualized on the basis of the at least one individual feature of the security document and at least one feature is inscribed as a diffractive structure. Thus, both directly recognizable Level-1 features as well as Level-2 or Level-3 features can be linked together and realized in one security feature.

Previously, the inventive method for applying a security feature on a security document and the security document itself has been described in such a way that the security feature is arranged in the region of the recess in the carrier layer. In this compilation on the one hand, the security feature of the transparent window in the Security document itself and on the other hand, the security feature of a microstructure with at least one individual feature linked.

Alternatively, it is also possible to write the security feature in a storage film and to secure it at a predetermined location on the carrier layer. For this purpose, no recess in the carrier layer is required as a window. Even if the feature of the transparent window is omitted as a security feature, at least one individual feature of the security document can be incorporated in an individual security feature in the form of a microstructure, which after reflection on the carrier layer of the security document is viewed or read out in reflection can be. This embodiment therefore constitutes an independent invention in comparison to the method described in claim 1 or in comparison to the security document described in claim 14.

All the features described above, which do not relate to the recess and / or the interaction of the storage foil with the window foil, are also applicable to the alternative of the invention described above.

The above-indicated technical problems are inventively at least partially solved by a security document, in particular a banknote with the features of claim 14. The specified in the dependent claims further features and the associated advantages are explained in more detail in the following description of exemplary embodiments.

Reference is made to the accompanying drawings. In the drawing show

1 shows a first embodiment of an apparatus for carrying out the method for applying a security feature on a security document,

Fig. 2 shows a second embodiment of a

Apparatus for carrying out the method for applying a security feature to a security document,

3 shows a first exemplary embodiment of a security document according to the invention with a security feature,

4 shows a second exemplary embodiment of a security document according to the invention with a security feature,

5 shows a third exemplary embodiment of a security document according to the invention with a security feature,

6 shows a fourth exemplary embodiment of a security document according to the invention with a security feature, 7 shows a fifth exemplary embodiment of a security document according to the invention with a security feature,

8 shows a sixth exemplary embodiment of a security document according to the invention with a security feature,

9 shows the layer structure of an embodiment of a storage film,

Fig. IO is a schematic representation of the possible

Structures in the functional layer of the memory film shown in FIG. 9 and

FIG. 11 shows a schematic representation of the further possible structuring in the functional layer of the storage film illustrated in FIG. 9.

The invention will be explained below with reference to the production of a banknote as an example of a security document. It is emphasized that the invention is not limited to the use in the production of banknotes. As already explained above, the invention can be applied to any security documents such as a credit card, a check card, an admission ticket or a label.

1 and 2, the inventive method for applying a security feature on a bill in two alternatives is shown and described. FIGS. 3 to 7 show various banknotes 10 according to the invention, which are produced from a carrier layer 12. In the carrier layer 12, a recess 14 is provided in each case, which forms a window. Furthermore, a transparent window film 16 is arranged on one side of the carrier layer 12, which completely covers the recess 14. The window film 16 may therefore have any shape. In the preferred embodiments illustrated in FIGS. 3 to 6, the window film 16 is formed as a strip which covers the carrier layer 12 from the upper edge shown in the figures to the lower edge.

A first embodiment of the method according to the invention is shown in FIG.

In a first step, at least one individual feature of the banknote 10 is determined, wherein in the present embodiment, a sorting device 20 is used, which is provided at the end of a plant for the production of banknotes. The transport of the banknotes 10 in this system is indicated by the line 22. With the aid of the sorting device 20, in addition to the serial number of the banknote 10, further features are included which are used as security features. If errors of the banknotes 10 occur during the check, these banknotes 10 which are not to be used are sorted out. Another object of the sorting device 20 is that the recorded features are stored in a memory to be used later for further processing and registration of the banknotes 10 can. Via a data line 24, these data are at least partially transmitted to the control of a lithograph 26. There, the security feature, which is identified by the reference numeral 28 in FIGS. 3 to 8, is generated on the basis of at least one of the individual features of the banknote 10. The at least one individual feature of the banknote 10 is thereby used, if appropriate using further features, for the calculation of a point distribution of a microstructuring.

This microstructuring is then written as a security feature 28 with the aid of the lithograph 26 in a storage film 30, wherein a plurality of individual storage sheets 30 is supplied as a roll product 32 of a laminating device 34. Via a further data line 36, the application of the correct storage film 30 to the respective banknote 10 is then synchronized starting from the sorting device 20. This can be done for example by a suitable triggering of the banknote transport. Finally, the rolls are rolled up on a roll 38 after transferring the storage sheets 30.

In the lamination device 34, the storage film 30 is then connected to the window film 16 together with the security feature 28 in the region of the recess. The connection between the window film 16 and the storage film 30 can preferably be effected directly by means of an adhesive, by means of a lacquer, in particular UV lacquer, or by high-frequency welding. Likewise, the storage film 30 be indirectly connected via the carrier layer 12 with the window film 16. The individual embodiments are explained below with reference to FIGS. 3 to 7.

It has previously been explained that the at least one individual feature of the banknote 10 is read from a data store in order to calculate a security feature 28 from it and to write it into the storage film.

FIG. 2 shows a further embodiment of a device for carrying out the method according to the invention, in which, once again, after the production of banknotes, a security feature is applied to the banknote.

In contrast to the first exemplary embodiment, the at least one individual feature of the banknote is read directly from the banknote, for which purpose a reading device 40 is provided. By means of a transport line 42, the banknotes are fed to the reading device 40 and at least one security feature is detected for each banknote. The captured data of the security features are transmitted to the lithograph 46 via a data line 44. The control of the lithograph 46 calculates from the transmitted data the point distribution of an individual microstructure, which is then inscribed directly into the material of the window foil 16 of the banknote 10 by means of a laser 48.

Thus, no data storage of a connected to the plant for the production of banknotes sorting device is used because the security features of the banknotes can be detected directly before generating the new security feature.

The two embodiments of the apparatus for carrying out the method explained above differ s ^~ I thus on the one hand, when and how the security features of banknotes are detected, and on the other hand in the manner in which the new security feature to the bank note is connected. However, the two combinations explained are not meant to be limiting. Thus, for example, in a further device for carrying out the method by means of the reading device 40, the security features can be detected, which are then subsequently processed by means of the lithograph 26 to form new security features 28 and written on memory sheets 30. The data of the

Sorting device 20 are used to write using the lithograph 46 security features 28 directly on window films 16.

In the following, various embodiments of bank notes according to the invention will be explained with reference to FIGS. 3 to 7.

3 shows a first exemplary embodiment of a banknote 10 according to the invention in a top view and in a cross section. In the carrier layer 12, a recess 14 is provided, which releases an opening in the banknote 10. In the cross section of the banknote according to FIG. 3 it can be seen that on the underside of the carrier layer 12 a window film 16 is provided which covers the recess 14. Furthermore, one is individualizing feature 50 in the form of a serial number printed on the carrier layer 12. In known manner, this serial number 50 represents an individual identifier for each banknote. In addition, further individualizing features may be present in the form of characters or patterns which are also unique to each banknote.

According to FIG. 3, a security feature 28, which has been generated on the basis of the at least one individual feature of the banknote 10, for example the serial number 50, as microstructuring, is connected to the window foil. In this case, the microstructuring can be calculated, for example, as a computer-generated hologram and / or as a microimage and / or microprint alone or in combination.

The security feature 28 is connected to the window film 16 in the region of the recess 14. For this purpose, the security feature 28 is inscribed in a storage film 30, which is indirectly connected to the window film 16 via the carrier layer 12. Thus, a gap 52 is formed between the window film 16 and the storage film 30. If the window film 16 and the storage film 30 are sufficiently resistant to bending, the quality of the clearance 28 when read out of the security feature 28 by means of a light beam is not or only slightly reduced by the gap 52.

In Fig. 3 it can be further seen that the storage film 30, the recess 14 covers, so that the edges of the recess 14 from both sides of the Carrier layer 12 ago seen completely covered. As a result, the edges of the recess 14 are protected when using the banknote 10 from tearing. The dimensions of the storage film 30 have been chosen so that they correspond to the dimensions of the window film 16. As a result, a symmetrical structure of carrier layer 12, window film 16 and memory film 30 is achieved. If the materials of the window film 16 and the storage film 30 are chosen to be similar or identical, the symmetrical structure prevents bending or warping of the banknote 10 'by mechanical stresses that arise.

The material of the carrier layer 12 of the banknote 10 consists of a conventional material such as paper, fabric or plastic. The window film 16 consists of an at least partially transparent plastic, for example polyethylene (PET) or polycarbonate (PC). The storage film 30 may also consist of an at least partially transparent plastic such as polyethylene (PET) or polycarbonate (PC). Preferably, the storage film 30 and the window film 16 made of the same material, so that the materials are matched in their thermal behavior to each other. One of the films may also be a polarizing film.

Typical dimensions of the carrier layer 12, the window foil 16 and the storage foil can be given as follows for the example of the banknote 10. The carrier layer 12 usually has a thickness of about 30 to 100 μm. The thickness of the window foil 16 may correspond to approximately one quarter to one third of the thickness of the carrier layer 12, preferably 10 to 25 μm. The storage film 30 may typically have a thickness of about 5 to 40 microns.

FIG. 4 shows a further exemplary embodiment of a banknote 10 according to the invention, wherein identical reference numerals denote the same features as in FIG. 3. In contrast to the first embodiment, the dimensions of the storage film 30 have been chosen smaller. The storage film 30 no longer extends from the upper edge to the lower edge of the carrier layer 12, but the storage film 30 covers only the edge regions of the recess 14 from. As a result, as previously described, the edges of the recess 14 are similarly protected from tearing. Due to the smaller size of the storage film 30, however, material is advantageously saved in comparison to the first exemplary embodiment.

According to FIG. 4, the storage film 30 is adhesively bonded to the window film 16 in the region of the recess 14, for which purpose an adhesive 54 is provided in the intermediate space between the storage film 30 and the window film 16. In this case, the adhesive 54 is at least partially transparent in order to ensure the window function of the recess 14 together with the window film 16 and the storage film 30.

FIG. 5 shows a further embodiment of a banknote 10 according to the invention, wherein the same reference numerals denote the same features as in FIGS. 3 and 4. In contrast to the previous embodiments, the storage film 30 is within the recess 14 and not arranged overlapping with the carrier layer 12. This can be seen in particular in the cross section shown in Fig. 5. The advantage of this embodiment is that the storage film 30 does not increase the thickness of the banknote 10, so does not apply. The storage film 30 is likewise glued to the window film 16 with an adhesive 54.

Fig. 6 shows a further embodiment of a banknote 10 according to the invention, wherein like reference numerals denote the same features as in Figs. 3 to 5. In contrast to the previous embodiments, the security feature 28 has been written directly into the window film 16 in the area left free by the recess 14. Thus, the window film 16 itself carries the security feature 28. This has the advantage that no separate storage film is needed and thus an additional effort is avoided. In particular, during the writing process for producing the security feature 28 in the window film 16, however, it must be ensured that the window film 16 is level, since the writing of microstructures with the aid of lithographs requires a very precise keeping of the distance between the window film and the lithograph.

FIG. 7 shows a detailed view of a storage film 30 bonded to a window film 16. With the aim of keeping the adhesive layer 54 as thin as possible, both the window foil 16 and the storage foil 30 are bent toward one another into the recess 14. By the adhesive layer 54, the two films are substantially the entire surface connected to each other, so that no interfaces with large refractive index differences arise that would adversely affect the optical properties of the composite of window film 16 and memory film 30.

In the enlarged section in Fig. 7 then the concrete structure of the two films can be seen. The lower layer represents the window film 16. Above this is the adhesive layer 54, which forms the connection to the storage film 30. The storage film 30 in turn consists of a substrate 56 and a functional layer 58, wherein the substrate 56 is preferably made of a polyethylene (PET) and the functional layer 58 is made of aluminum.

FIG. 8 shows a further exemplary embodiment of a banknote 10 which, in contrast to the exemplary embodiments explained above, has no recess in the carrier layer 12. It is thus an embodiment without windows, in which the storage film 30 is applied with an inscribed security feature 28 in the form of a microstructure directly on the carrier layer 12. Accordingly, the security feature can only be measured or recorded in reflection, since a window for a measurement in transmission is missing.

But even in this embodiment, the basic idea is realized that starting from an individual security feature 50 in the form of, for example, a serial number, an additional security feature 28 subsequently generated and with the Banknote 10 is connected. As a result, as in all exemplary embodiments, redundancy in the individual features can be obtained beforehand.

Previously, it has already been mentioned several times that the security feature 28 consists of a microstructure, which can be written either in the separate memory film 30 or directly in the window film 16. In the selection of microstructuring, there are a number of ways in which information can be included in the microstructure.

A preferred embodiment consists in that at least one feature observable in reflection is inscribed in at least one functional layer 58 of the memory film 30 and that at least one feature observable in transmission is inscribed in the at least one functional layer 58 of the memory film 30. In this case, at least one feature is individualized on the basis of the at least one individual feature 50 of the banknote 10 and at least one feature is inscribed as a diffractive structure. By means of this combination of features which can be observed in reflection and in transmission, it is possible in particular to exploit the function of the recess 14 as a window in the banknote 10, since it is only through the window that observation of at least one of the features observable in transmission is possible.

A preferred memory film 30 will be explained below with reference to FIGS. 9 to 11, wherein the process of writing a microstructure into the functional layer 58 will also be described. A storage film shown in FIG. 8 consists of a polymer film 56, preferably of a stretched polymer film which is at least partially transparent to visible light, and of at least one functional layer 58 which absorbs the laser radiation during the lithographic writing process and is at least partially transparent. Between the film 56 and the functional layer 58, preferably no further layers are arranged. In addition, a further additional layer 60 may be present on the side of the functional layer 58 facing away from the polymer film 56.

The additional layers 60 can be lacquers, protective layers, polymer layers, transparent glasses, crystalline layers, semiconductors, antireflection layers or further functional layers.

The lithographic writing can take place in FIG. 9 from below through the film 58 onto the functional layer 58 or else from the top onto the functional layer 58 through the optional additional layer 60. During the lithographic writing process, the function layer 58 has inter alia the task of at least partially absorbing the laser radiation, converting it into heat and at least partially delivering it to the film 56.

Instead of a functional layer 58, it is also possible to provide two and more functional layers 58 arranged one above the other, which complement or reinforce each other in their function. FIGS. 10 and 11 show various types of structures which can be produced in a lithographic process or writing process using, for example, laser radiation. Here, the structure of the memory sheet 30 is substantially that of the storage foil 30 shown in Fig. 9, the at least one functional layer 58 and the optionally present additional layer 60 corresponds, consisting of the ^'film 56.

If the information to be written is introduced into the storage film 30 by means of a lithographic system using focused laser radiation, a focused laser beam generates a small structure in the storage film 30 by a short laser pulse or several consecutive pulses, which together with many such written Structures yield the desired diffractive or holographic or directly visible overall structure of the microstructure.

The following differently generated and differently acting structures can be realized.

In Fig. 10, structure 62 represents a structure of type la +, structure 64 represents a structure of type Ib +, and structure 66 represents a structure of type 2.

In FIG. 11, the structure 68 represents a type Ia structure, the structure 70 is a type Ib structure, and the structure 72 is a type 3 structure. Depending on the temperature during the lithographic writing process in the

Functional layers or the film is present, the structures shown in Figs. 10 and 11 can be produced.

10 shows, on the one hand, re-image formation on the basis of the structure 62 as an increase of the film surface by type la + a certain height and on the basis of the structure 64 an increase of the film surface of the type 1b + with a greater height than in the structure 62 with type la +. On the other hand, a removal of the at least one functional layer 58 by the example of the structure 66 corresponds to the type 2, which corresponds to a demetallization in the case where one of the functional layers 58 is a metal layer.

FIG. 11 shows relief formations on the basis of the structure 68 with type Ia and on the basis of the structure 70 with type Ib-, similar to the types la + and lb +, but in the form of a depression of the film surface. Fig. 11 also shows a pattern formation in the form of the structure 72 of type 3, which changes the phase of the light when illuminated with a reading beam. The structure 72 may be formed, for example, in the form of a refractive index change of the film 56. A type 3 structure may also be a gas bubble formed by the exposure process.

Depending on the size of the energy absorbed during the writing process, which is converted into heat, as well as the amount of heat transferred to the film and the thermodynamic behavior of the film and the functional layer (s) can be formed in the film or else demetallizations or structural changes of type 3 are achieved.

As a suitable process parameter, the total energy of a single laser write pulse can serve this purpose in a lithographic process. With the same laser power different energies can be introduced into the storage medium with different lengths of laser pulses. Short pulses produce low energies, middle pulses medium energies and long pulses generate high energies. This allows both the type of exposure and the severity, i. Within certain limits, the size of the exposed point can be influenced.

Structures of the type Ia, ie low relief formations can be generated with low energies. Structures of the type Ib, ie strong relief formations can be generated with medium energies. Type 2 structures, ie demetallizations, and type 3 structures can be generated at high energies.

For example, with suitable laser lithographs (diffraction-limited, 100-lOOOmW laser power in the visible or IR, UV range) with the same material and the same laser power types Ia, Ib and 2 are generated with laser pulse lengths of 150ns, 300ns and 600ns.

As a further process parameter, the laser power can be used in a lithographic process. For equally long pulses with weak, medium or high Laser power, type Ia, type Ib or type 2 and type 3 structures can be generated.

As a further process parameter, the number of individual pulses can be used in a lithographic process. For pulses of equal energy, e.g. a type Ia structure is generated with a pulse, a type Ib structure with a double pulse (2 pulses with a short pause), and a type 2 or type 3 structure with a triple pulse.

Further combinations of number of pulses, laser power, pulse duration and / or temporal laser pulse spacing are possible.

In the following, the properties of generated structures of types Ia, Ib, 2 and 3 are described in detail, it being within the scope of the invention to combine the properties of differently configured layers.

Relief formations have an influence on the phase of the light when reading in reflection and are thus diffractive phase patterns. In transmission they do not act or hardly.

Phase changes in the film or blistering lead to phase influence in reflection and transmission.

Demetallizations have an influence on the amplitude of the light both during reading in reflection and during reading in transmission and are thus diffractive amplitude patterns. A storage film can be described lithographically with a structure according to type Ia with the following properties:

Functional layers are retained so that no change in optical density (OD) when viewed in transmission with e.g. White light occurs.

Lattice structures that are formed from relief formations, when viewed in reflection, lead to diffraction phenomena. Grids or complex grids can appear in different colors.

Holographic structures can be read in reflection with a suitable device.

Relief formations in transmittive illumination lead to almost no diffraction or to diffraction effects with negligible diffraction efficiencies.

A storage film can be described lithographically with a structure according to type Ib with the following properties:

Lattice structures that are formed from relief formations, when viewed in reflection, lead to diffraction phenomena. Grid or complex grid can appear in different colors and are lighter than the same type Ia structures.

Holographic structures can be read in reflection with a suitable device and diffract more than type Ia structures.

A storage film can be described lithographically with a structure according to type 2 with the following properties:

Functional layers are not preserved so that a change in optical density (OD) when viewed in transmission with e.g. White light results. This effect can take place areally and thus result in maximum transmission or else lead to a desired gray value via a corresponding rastering of metallized and demetallised area.

Lattice structures formed from amplitude patterns, when viewed in reflection, lead to diffraction phenomena. Grids or complex grids can appear in different colors.

Grating structures formed from amplitude patterns, when viewed in transmission, give rise to diffraction phenomena. Holographic structures can be read in reflection with a suitable device.

Holographic structures can be read out in transmission with a suitable device or the naked eye by means of a suitable light source.

A storage film can be described lithographically with a structure according to type 3 with the following properties:

Lattice structures, when viewed in reflection, lead to diffraction phenomena. Grids or complex grids can appear in different colors.

Lattice structures lead to diffraction phenomena when viewed in transmission.

Holographic structures can be read in reflection with a suitable device. Holographic structures can be read out in transmission with a suitable device or the naked eye by means of a suitable light source.

The following describes the preferred combinations of various structures.

As described above, the various types of memories, i. Surfaces described by types Ia, Ib or 2 or 3 contain different information.

For example, holographic structures can contain digital data, texts, numbers, serial numbers, images, faces, logos, patterns, encoded data, etc. in their reconstruction.

Identical data contents can be generated by diffractive structures as diffraction patterns. Likewise, such information contents can be generated as gray value images by demetallization, which are viewed in a transmissive arrangement.

Different information contents can be combined with each other. Thus, a pictorial information, for example a microimage in the form of a number, can be combined with a hologram in such a way that the number can be seen when viewed in reflection with the naked eye, but the same structure also displays holographic information when reading out with the aid of a corresponding reading device contains. From the above-described concrete embodiment of different structures in the functional layer 58, the following properties of the security feature 28, which is inscribed in the form of a microstructure in a memory film 30, can be indicated:

At least one feature observable in reflection is formed as a relief structure in at least one reflective functional layer 58 of the storage film 30.

at least one feature observable in reflection is designed as a structure with different optical density, in particular as an at least partially perforated reflective functional layer 58.

at least one feature observable in reflection is a structure which is reflective-diffracting or reflective by brightness modulation.

At least one feature observable in transmission is designed as a structure with different optical density, in particular as an at least partially perforated reflective functional layer 58.

At least one feature observable in transmission is designed as a structure which can be transmittively diffracted or transmissively observed by brightness modulation. at least one transmissive or reflective observable feature is a computer-generated hologram.

Thus, according to the present invention, a security document, such as a banknote 10, may be provided with a security feature 28 in the form of a microstructure, wherein at least one feature is a Level-1 security feature and wherein at least one feature is a Level-2 or Level-3 In addition, at least one feature can itself be customized with the aid of an individual feature 50 present on the banknote 10, whereby a redundancy of the individual features is obtained ^' Transmission can be read as well as in reflection.

Typical ways of reading the information stored in different ways can be, for example:

Observation of shiny metallic structures in reflection with the naked eye, whereby different levels of brightness can be observed.

Observing diffractive structures in reflection with the naked eye, wherein different brightnesses and / or colors can be detected.

Reading holographic structures in reflection with a suitable device. Reading diffractive or holographic structures in transmission with a suitable device or with the naked eye by means of a suitable light source.

Reading out structures in transmission that result from brightness modulation (gray value images) with coherent, but especially with non-coherent light, for example, with normal daylight, with a lamp, with a light bulb, etc ..

Claims

PATENT TO SP RU CHE

1. A method for applying a security feature on a security document, in particular on a banknote, wherein the security document a carrier layer having at least one recess and at least one

Having recess covering transparent window film, wherein at least one individual feature of

Security document is determined, in which the security feature on the basis of at least one individual feature of the

Security document is generated and in which the security feature in the field of

Recess is connected to the window film.

e

2. The method of claim 1, wherein the at least one individual feature of the security document is read from a data store.

3. The method of claim 1, wherein the at least one individual feature of the security document is read directly from the security document.

4. The method according to any one of claims 1 to 3, wherein the security feature is written in a storage film and where the storage foil is connected to the window foil.

5. The method of claim 4, wherein the storage film is glued in the region of the recess at least partially with the window film.

6. The method of claim 4 or 5, wherein the storage film is applied to the recess overlapping.

7. The method according to any one of claims 4 to 6, wherein the storage film is applied with the same dimensions as the window film on the security document.

8. The method according to any one of claims 4 to 6, wherein the storage film is applied with smaller dimensions as the window film.

9. The method of claim 4 or 5, wherein the storage film is disposed within the recess and not overlapping with the carrier layer.

10. The method according to one of claims 1 to 3, wherein the security feature is written directly into the window film.

11. The method according to any one of claims 1 to 10, wherein the security feature is written using a laser lithograph in the storage sheet or window film.

12. The method of claim 11, wherein the security feature is written as a microstructure.

13. Method according to claim 11, wherein at least one feature observable in reflection is inscribed in at least one functional layer of the storage film and in which at least one feature observable in transmission is inscribed in the at least one functional layer of the storage film, whereby at least one feature on the Basis of the at least one individual feature of the security document is individualized and wherein at least one feature is inscribed as a diffractive structure.

14. Security document, in particular banknote having a carrier layer (12), with a recess (14) arranged in the carrier layer (12), with a transparent window foil (16) connected to the carrier layer (12) and covering the recess, and with at least one individualizing Feature (50), characterized in that a security feature (28) generated on the basis of the at least one individual feature (50) of the security document is connected to the window film (16) in the region of the recess (14).

15. Security document according to claim 14, characterized in that the security feature (28) is inscribed in a storage film (30) and that the storage film (30) is connected to the window film (16).

16. Security document according to claim 15, characterized in that the storage film (30) in the region of the recess (14) is at least partially bonded to the window film (16).

17. Security document according to claim 15 or 16, characterized in that the storage film (30) the recess (14) is applied overlapping.

18. Security document according to one of claims 15 to 17, characterized in that the storage film (30) with the same dimensions as the window film (16) on the carrier layer (12) is applied.

19. Security document according to one of claims 15 to 17, characterized in that the storage film (30) is applied with smaller dimensions as the window film (16) on the carrier layer (12).

20. Security document according to claim 15 or 16, characterized in that the storage film (30) is arranged overlapping within the recess (14) and not with the carrier layer (12).

21. Security document according to claim 14, characterized in that the security feature (28) is inscribed in the window film (16).

22. Security document according to one of claims 14 to 21, characterized in that the security feature (28) as

Microstructuring is inscribed.

23. A security document according to claim 22, wherein at least one feature observable in reflection is inscribed in at least one functional layer (58) of the storage film (30) and in that at least one in transmission in the at least one functional layer (58) of the storage film (30) is inscribed, wherein at least one feature is individualized based on the at least one individual feature (50) of the security document, and wherein at least one feature is inscribed as a diffractive structure.

24. Security document according to claim 23, characterized in that at least one observable in reflection Feature is formed as a relief structure in at least one reflective functional layer (58) of the storage film (30).

25. Security document according to claim 23 or 24, characterized in that at least one feature observable in reflection is formed as a structure with different optical density, in particular as an at least partially perforated reflective functional layer (58).

26. Security document according to one of claims 23 to 25, characterized in that at least one feature observable in reflection is a structure that is reflective-diffractable or reflective by brightness modulation.

27. Security document according to one of claims 23 to 26, characterized in that at least one observable in transmission feature as a structure with different optical density, in particular as at least partially perforated reflective functional layer (58) is formed.

28. Security document according to one of claims 23 to 27, characterized in that at least one observable in transmission

Characteristic as a transmissive-diffractive or transmissively formed by brightness modulation observable structure is formed.

29. Security document according to one of claims 23 to 28, characterized in that at least one transmissive or reflective observable feature is a computer-generated hologram.

30. Security document according to one of claims 23 to 29, characterized in that at least one feature is a level-1 security feature and that at least one feature is a level-2 or level-3 security feature.