HK1039194B - Substrate which is made from paper and is provided with an integrated circuit - Google Patents

Description

Substrate made of paper and provided with integrated circuit

The invention relates to a substrate made of paper and provided with at least one integrated circuit.

Such substrates are known from german patent application DE-19601358, which is used for security documents and banknotes to prevent counterfeiting and fraud. Such known substrates comprise an integrated circuit incorporated in the substrate and containing predetermined data. The IC is non-contact readable and is non-detachably coupled to the substrate. The IC used for such a substrate is a conventional IC, known as a silicon-type IC. The size of the originally manufactured chip is reduced by etching or polishing so that the chip has the desired thickness when it is incorporated into a paper product. To prevent damage to the crystal circuit, the IC is reinforced with a support layer, which also serves to position the IC. In addition, the IC is covered with a chemical resistant protective layer. The lack of flexibility of the known silicon chips is a disadvantage when such substrates are used as security papers, such as banknotes and identity documents. Furthermore, the additional layers to be included and the additional processing steps to make the appropriate dimensions result in an increase in the cost price of such substrates.

It is an object of the present invention to provide a paper substrate for security documents, banknotes and the like, in which an integrated circuit is incorporated, which substrate does not have the above-mentioned disadvantages.

According to the invention the object is achieved with a substrate as described above, wherein the integrated circuit comprises a semiconducting organic polymer. This means that the electronic circuitry is provided in a polymer material, the composition of which is designed to give it a specific function. Such polymer chips are very flexible and are therefore particularly suitable for use in security documents such as banknotes. Even chips made of semiconducting organic polymers have significant creases which do not hinder the functioning of the chip. Furthermore, polymer ICs can be manufactured directly in the desired dimensions, in particular thickness dimensions, the cost of such chips being reduced by approximately 10% compared to the current lowest price of silicon-based chips.

In polymer chips, the thickness of the entire integrated circuit is primarily determined by the non-conductive support on which the semiconducting polymer material is to be deposited. It is preferable to use an insulator having high mechanical strength: plastics with strong internal and external molecular interactions are particularly suitable for this purpose.

Using such ICs as security markings in security paper, similar items can provide new and powerful protection, since the manufacture of such ICs is too complex for counterfeiters, generally far beyond their knowledge and capabilities.

For the purposes of the present application, paper is understood to mean paper composed of natural or synthetic fibers and "paper" which nowadays can be manufactured from plastic films, which is used for the manufacture of security papers, banknotes and the like.

The integrated circuit may have one or more and may be adjusted according to the desired functionality. For example, two or more identical polymer chips may be introduced for certain operations so that in the event of failure of one of such chips, the substrate and/or the end product made therefrom may still be used.

The organic polymer is preferably selected from conjugated polymers, in particular from oligomeric pentacene, poly (thienylethylene) or poly-3-alkylthiophenes. An IC made from one of these materials is described by Brown et al in Science 270, pages 972-974 (1995).

As will be appreciated by those skilled in the art, the plastic ICs used in the present invention include additional layers of different polymers within the semiconductive polymer layer. For example, the substrate may be made of polyimide on which polyaniline blocks may be formed to serve as a source and a drain. On which a semiconducting polymer layer is present, for example comprising poly (thienylethylene). This layer is covered by an insulating layer such as polyvinyl phenol, and the upper layer of polyaniline is the uppermost layer, functioning as a gate electrode.

In an embodiment of the substrate according to the invention, the integrated circuit is contactlessly readable, the data transmission being performed inductively or capacitively, as is known in the art.

In the case of inductive read-out, the coil requires a current supply, has to be conductively connected to the IC; thereby allowing remote reading. In order to be able to read at close distances, the IC is required to contact a conductor, which together with the measuring device forms a capacitance, whereby current supply and reading is possible.

According to another preferred embodiment of the substrate according to the invention, the substrate comprises electrically conductive security threads connected to the integrated circuit, said security threads serving as direct and indirect contacts for reading and supplying current. In its preferred embodiment, the security thread is metallized to provide the required conductivity, except at the location of the polymer IC where the metal deposition is interrupted. In the case of direct supply of current, the metal must be accessible. Possible ways of being able to access include a security thread introduced into the substrate and a metal part accessible through a so-called window. Advantageously, the one or more integrated circuits are part of the security thread itself. The thickness of the security thread may be adapted to the intended use of the substrate, for example for banknotes. For banknote sheets, the thickness of the paper substrate is typically in the range up to 100 microns. In this case, the thickness of the security thread is preferably in the range of 15-60% of the thickness of the substrate. If the paper substrate is of different thickness, for example for use in an identity document such as a passport, a security thread having a minimum thickness of about 10 microns is used. Thicknesses above 100 microns are not meaningful for security paper. Preferred embodiments of the polymer IC in the form of a security thread provide a security feature that is readily recognizable to the public. The security thread comprising the integrated circuit may additionally comprise a number of other features, such as dyes, fluorescent or phosphorescent materials, luminescent materials and printed markings.

It is also possible to supply the chip with an electric current using organic conductive polymers, although in the case of direct contact, the mechanical contact properties of these polymers are at present at a distance from what is expected.

ｃA simple security thread consisting of an electrically conductive polymer is proposed in european patent application EP- ｃA-0753623. Such security threads are only electrically conductive and not semiconductive and therefore it is not possible to apply and store codes in a manner comparable to conductive polymer threads incorporating integrated circuits. The security thread comprising an integrated circuit according to the invention can be provided in a conventional manner, for example by being incorporated or integrated completely in the paper product, in a window or by being applied to the surface of a document. If chemical attack is to be prevented, a chemical-resistant non-conductive protective layer may be applied over the conductive organic polymer of the chip.

As in the case of the silicon chips in the abovementioned German patent application, the polymer chips do not have to be each incorporated completely into the paper. Instead, the polymer IC may be disposed on the surface of the substrate using conventional techniques for attaching metal foils, holograms, other optically active elements, and the like.

The integrated circuit itself may advantageously also form part of all optically active elements, such as metal foils, patches, holograms or active patterns, arranged on or in the substrate as an additional security feature. Like the above description of the security thread, it is also possible according to another preferred embodiment to manufacture such optically active elements in such a way that two different conductive parts of these elements are used for direct and capacitive reading and current supply. The conductive member may be composed of a metal, a conductive polymer, or a composite thereof.

For protection purposes, the integrated circuit may include a pre-programmed code that is added before the chip is introduced to the substrate.

Advantageously, the integrated circuit comprises a coding of the intrinsic properties of the substrate in which the circuit is incorporated.

According to the current state of the art, a polymer IC can only be used in one direction, i.e. it can be written or programmed once. The preferred way to store the code in the IC is to use a technique derived from cryptography. The actual code is then stored in the IC in an encrypted manner and cannot be decoded without knowledge of the password. Thus, even if an unwritten chip is obtained illegally, the password constitutes a powerful practical fort that prevents counterfeiters from adding information to the secure document and reading that information. As will be described in more detail below, the protection function can be further improved if any partial programming of the chip is performed after the IC has become part of the security document.

The shape of the polymer chip is not critical. Currently, a rectangular size of about 1mm represents a lower limit of the surface size if a reasonable number of bits are to be stored in the IC. Rectangular ICs of 4mm by 6mm currently store about 48 bits, i.e. 2 bits/mm². The surface size ratio (i.e., length to width) of the polymer chips should preferably not exceed 10: 1, since undesirable buildup can occur given a larger ratio of chips. The small size of the IC offers the possibility to cover the chip with additional features commonly used in the prior art. The size of such additional features is generally larger than the size of the polymer IC. Larger ICs with sufficient storage capacity to store large amounts of data can also be used without affecting the appearance of the security paper. If chips with further security markings are provided together on the security paper, it is necessary to ensure that the reading of the chips and the current supply are not subject to such an additionThe impact of the security features.

Substrates comprising polymer ICs according to the present invention are used as security paper in other security documents such as banknotes, passports, identity cards and securities.

The development of such inexpensive integrated circuits offers a number of new possibilities for preventing counterfeiting of security documents, starting with completely new electronic devices (electronic barcodes) in security paper.

The use of an IC as an example of a security feature in a document to be described has many possibilities for banknotes, but the same possibilities exist for other types of security documents, such as passports, identity cards and the like

A first possibility involves using fully programmed ICs in a paper substrate. If an encrypted form is desired, the IC contains one or more codes for the banknote. Such information may include the value, country, setting and/or time, quantity, etc. of the product. The information on each chip is substantially the same for a particular denomination of banknote, i.e. denomination, country, and paper maker and/or printer are the same, and may differ in part, i.e. in time of manufacture, number of manufactures, and sometimes paper maker and/or printer.

With a chip pre-programmed with a unique code (first code) and an additional second code part, a more specific protection can be achieved. The second encoding is a cryptographic decode of the first encoding. The encryption is performed using a first password. And reading the second code during verification, and verifying the encryption relationship with the first code by using the second password. The second code may be applied to the chip before or after the chip is disposed on the substrate. Such an encryption system is described, for example, in WO-A-97/24699.

In this known system, the inherent characteristics of the subject matter are encoded, encrypted and decrypted. For banknotes, the surface features occupy specific locations, are coded, encrypted and stored as printed patterns on the banknote. Upon verification, the printed pattern is compared to the surface features using the second password.

Many other features and features randomly distributed on A substrate have been used in the prior art as A protection measure for security documents, see WO-A-91/19614 (fibre orientation), GB-A-230407 (reflective flakes), US-A-4218764 (magnetic particles or fibres) and WO-A-87/01845 (conductive fibres). In all of these cases, any and thus unique features on the document are used for authentication. To date, there has not been a suitable chip for use with a paper substrate to store (encrypt) the code, so the features being encoded are always stored in other ways, for example outside the document itself, or printed in or on the document, or magnetically recorded therein. The polymer chip used for the substrate according to the invention can technically use these protective features within the document and store them within the document.

The fluorescence of fluorescent fibers randomly distributed in a predetermined area of the banknote is a suitable feature. However, other characteristics that can be measured and randomly distributed in and on the paper may be used. One condition is that the features used must be stable over the life of the document, meaning that in principle any feature that is very relevant to the progress of use, such as soiling, folding, etc., is not suitable.

If necessary, the coordinates of the relevant part of the banknote determining any feature and the orientation of the surface that must be detected, etc. can be stored in the chip. Thus, in validating a banknote, it is possible to measure a particular parameter along a predetermined path, or to obtain an image of the entire banknote, but only using the data found at the pre-encoded coordinates for discrimination. The results of such measurements are compared to stored codes of the same features at similar references to the same locations. Based on this comparison, which may be encrypted arbitrarily, a reject or accept signal is generated.

The substrate with the polymer IC according to the invention may additionally comprise conventional security features such as watermarks, security threads, optically active elements and special chemical properties, micro-printed dots, etc., which can be determined using standard techniques.

The invention also relates to a security wire or optically active element comprising an integrated circuit composed of a semiconducting organic polymer.

The following examples illustrate the invention. In this case, the particular fluorescence characteristics of the particular portion of the document are used as an example. Many banknotes carry a large number of strongly fluorescent fibers emitting light of different colors. These fibers are randomly distributed throughout the document. The local fluorescence of the various fibers at the predetermined positions can be encoded and digitally stored in the chip, optionally in an encrypted manner, at the time of manufacture of the document, i.e. during printing of the document. During verification, the coordinates and orientations stored in the chip are used again to read out the desired areas, the results are compared with each other and then indicate rejection or acceptance. The coordinates and orientation are generally different for each different banknote, with the result that the document is verified to be completely unique, since any feature and coordinate is unique to the document. In this way, the chip of each different banknote contains a unique mark whose specific code represents a specific part of said banknote. The encoding of the intrinsic characteristic may be stored in encrypted or unencrypted form.

As described above, the application of the substrate according to the present invention is not limited to banknotes. For other applications, such as passports and identity documents, part of the biometric characteristics of the legitimate holder may be used to generate a digital code which is then stored in the IC of the document. One such example would be a coded portion of a digital photograph of a legitimate holder, the portion to be digitized being determined by coding parameters specific to each type of file. For the given example above, document verification requires that the stored code of the photograph and the code actually read match each other overall. Biological parameters, such as their fingerprints or body members, can also be used and then stored in the polymer chip in an encoded manner. Here too the features to be encoded and stored must be stable.

To further illustrate the invention, reference is made to the accompanying drawings, wherein:

figure 1 shows a schematic plan view of one embodiment of a banknote according to the present invention;

figure 2 shows a cross-sectional view through the banknote shown in figure 1 along the line I-I;

figure 3 shows a schematic plan view of another embodiment of a banknote according to the present invention;

figure 4 shows an enlarged view of the optically active element for the banknote shown in figure 3;

fig. 5 shows a cross-sectional view through the optically active element shown in fig. 4;

figure 6 shows a cross-sectional view through a further embodiment of a banknote according to the present invention;

FIG. 7 shows yet another embodiment of a security thread with a polymer chip;

FIG. 8 shows another embodiment of an optically active element with a polymer chip;

fig. 9 shows a composite situation of the security thread and the optically active element; and

fig. 10 shows a further embodiment of a security thread according to the invention in a sectional view.

It should be noted that in the figures to be discussed below, like elements are given like reference numerals.

Fig. 1 shows a banknote 1 made of paper. The banknote 1 comprises a security thread 1 comprising a conductive chip 3 of a semiconducting organic polymer and, for example, a conductive metal component 4. In addition, the banknote 1 comprises a second chip 3', also made of a semiconducting organic polymer. As can be seen from the cross-sectional view of fig. 2, the security thread 2 is provided on the paper 5, while the second polymer chip 3' is embedded within the paper product 5. The embedded chip 3' is in contact with a conductor or coil to provide the required current and readout.

Figure 3 shows another embodiment of a banknote 1 in which a security thread 2, also comprising a polymer chip and a conductive member 4, is introduced into the sheet of paper. If desired, portions of the conductive portion 4 are contacted through the window 6 to form direct electrical contact. The banknote 1 shown in fig. 3 also comprises a second chip 3', in this case located below the optically active element 7. The optically active element 7 comprises electrically conductive members 8 separated by insulating, i.e. non-conductive, strips 9. The chip 3' can then be read and powered through the conductive means 8, whether by capacitive coupling or remote coupling. The conductive features may be covered with a chemically inert layer if a capacitive readout is to be made. If direct contact is desired, one part and the whole part 9 of the conductor may be covered in such a way that the IC and the conductor are protected, while the other parts of the conductor remain in direct contact.

Fig. 4 shows an enlarged view of a light element 7 with a chip 3', while fig. 5 shows a cross-sectional view through such a light element 7.

Fig. 6 shows a further embodiment of a security thread 2 with a chip 3 of a semiconducting organic polymer and a conductive means 4 applied to a paper 5. In this embodiment, the polymer chip of the security thread 2 and some parts of the conductive member 4 are protected by a layer 10 of chemically resistant non-conductive material. If capacitive coupling is used, the protective layer 10 may cover the entire security thread.

Fig. 7 shows a further embodiment of the security thread according to the invention, in which the chip 3 does not form part of the security thread itself, but is adjacent thereto. The conductive parts 4 of the safety wire 2 are electrically insulated from each other by means of an insulating block 4. The chip 3 is connected to the relevant conductive part 4 of the security thread by means of a conductor 12.

A similar embodiment for an optically active element is shown in fig. 8. The conductor 12 provides an electrical contact between the conductive part 8 of the optically active element and the polymer chip 3'.

Fig. 9 shows the combination of the security thread 2 and the optically active element 7, the metal part 4 of the security thread being in electrical contact with the metal part 8 of the optically active element 7. A chip 3' made of a semiconducting organic material is located below the optically active element 7.

Fig. 10 shows a further embodiment of a security thread according to the invention. In this embodiment, the security thread is constituted by the chip 3 and the conductive member 13, and both the chip 3 and the conductive member 13 are constituted by a conductive polymer. The security thread is provided on the paper 5. The polymer chip 3 is protected by a layer 10 of a chemical resistant material, which is (partly) covered with a conductive polymer 13. In order to ensure a very good supply and reading, a metal block 14 can be provided behind the insulating-material layer 10, the metal block 14 being electrically connected to the conductive organic polymer 13.

In the case of a capacitively coupled system, a protective layer may be added over the metal part 14 and the chemical resistant layer 10.

Claims (17)

1. A substrate made of paper and provided with at least one integrated circuit, characterized in that the integrated circuit is flexible and comprises a semiconducting organic polymer.

2. The substrate of claim 1, wherein said organic polymer is selected from conjugated polymers.

3. The substrate of claim 2, wherein said organic polymer is selected from the group consisting of oligomeric pentacene, poly (thienylethylene), and poly-3-alkylthiophenes.

4. A substrate according to claim 1, characterized in that said integrated circuit is a contactless readable IC, which can be read inductively or capacitively.

5. A substrate according to claim 1, characterized in that the substrate comprises an electrically conductive security thread (2) connected to the integrated circuit (3), wherein the security thread (2) is used as a contact for read-out operations and current supply.

6. A substrate according to claim 5, characterized in that said integrated circuit (3) is part of a security thread (2).

7. A substrate according to claim 5, characterized in that the thickness of said security thread (2) is in the range of 5-60% of the thickness of the substrate.

8. A substrate according to claim 1, characterized in that said integrated circuit (3') forms part of an optically active element (7), such as a metal foil, a hologram or a moving picture.

9. A substrate according to claim 1, characterized in that said integrated circuit comprises a pre-programmed code applied before the integrated circuit is introduced in the substrate.

10. A substrate according to claim 1, characterized in that the integrated circuit comprises a code of an intrinsic characteristic of the substrate, which code is provided in the integrated circuit after the substrate has been manufactured.

11. A substrate according to claim 9 or 10, characterized in that said code is an encrypted code.

12. The substrate of claim 1, wherein said substrate includes additional security features.

13. The substrate of claim 12, wherein said additional security feature is selected from the group consisting of a dye, a fluorescent material, a luminescent material, and a phosphorescent material.

14. A security paper comprising the substrate of claim 1.

15. A security document comprising the substrate of claim 1.

16. A security thread (2) comprising an insulating support (5) supporting a flexible integrated circuit (3) comprising a semiconductive organic polymer and with electrical contacts for the integrated circuit.

17. An optically active element (7) comprising a flexible integrated circuit (3') comprising a semiconducting organic polymer and having electrical contacts (8) for the integrated circuit.