WO2003057499A1

WO2003057499A1 - Valuable document or security document comprising a seebeck or peltier element

Info

Publication number: WO2003057499A1
Application number: PCT/EP2002/014440
Authority: WO
Inventors: Dieter Sauter; Anett Bailleu; Konstantin PÖTSCHKE; Oliver Muth; Daniel Grammlich; Manfred Paeschke; Arnim Franz-Burgholz; Benedikt Ahlers
Original assignee: Bundesdruckerei Gmbh
Priority date: 2002-01-10
Filing date: 2002-12-18
Publication date: 2003-07-17
Also published as: AU2002356666A1

Abstract

The invention relates to a valuable document or security document comprising a circuit and means (3,6,7,8) for converting thermal energy to electric power for supplying the circuit so that a security feature (2) is activated.

Description

Value or security document with Seebeck or Peltier element

description

The invention relates to a value or security document and a method for producing such a value or security document.

It is known from the prior art to store value or security documents, such as banknotes, identity cards, driver's licenses, stamps, entrance tickets, tokens, credit cards, check cards, shares, packaging

and the like, to provide security features which make it difficult or even impossible to forge or unauthorized modification of such documents. In this sense, a product is also referred to as a “document” which is provided with a corresponding security feature.

Well-known security features include watermarks. Such watermarks are visible in the back light and then show a specific motif or a number, such as the nominal value of the relevant banknote.

Another security feature is the security thread. The security check takes place in such a way that a darker line must be visible in the backlight.

Furthermore, it is known to apply special film strips with security features, such as holograms. The holograms make it possible, for example, for different symbols or numbers to appear when a banknote is tilted, depending on the viewing angle.

Furthermore, the use of pearlescent strips is known for realizing security features. When the banknote is tilted, a gold-colored stripe is visible, for example, in which a symbol and the respective value number can be recognized. Such a pearlescent strip is, for example, on the 20 EURO note.

From US 5,403,039 a printed document, such as. B. a lottery ticket is known, which has a thermochromic layer. The thermochromic layer is applied over data printed on the document. For authentication, the thermochromic layer is heated, for example by touching it with the finger. If the document is genuine, the color changes reversibly. A security document with a printed thermochromic material is known from US Pat. No. 5,826,915. The thermochromic material is heated by rubbing and then shows a corresponding security feature.

Furthermore, value or security documents are known from the prior art, which have a circuit:

From DE 695 09 783 T2 a prepaid card is known which has a thin housing in which sound generating means for generating a preselected sound pattern are located. There is also a power source in the housing to supply the sound generating means with electrical power.

A greeting card is known from DE 198 18 710 A1, which has a microphone for recording a voice message. The greeting card also has a loudspeaker for playing back the recorded voice message. The electrical components required to implement the corresponding circuit are interconnected by wires.

A birthday card with an image display function is known from DE 422 07 62 A1. For this purpose, a liquid crystal display and further discrete components are arranged on the card, which are interconnected via wires.

A security document is known from US Pat. No. 4,763,927, in which a security inlay with piezoelectric properties is located. The presence of this inlay can be checked by contacting it from the outside.

The invention is based on the object of creating an improved value or security document and an improved method for producing a value or security document. The object on which the invention is based is achieved in each case with the features of the independent patent claims. Preferred embodiments of the invention are specified in the dependent claims.

The present invention makes particular use of the so-called Seebeck or Peltier effect:

The functional principle of the Seebeck effect is based on the fact that a potential difference arises between two different metals that are brought into contact with one another, which is referred to as contact potential. This contact potential depends on the temperature.

A Seebeck element can be realized in that at least two contact points are made between different metals, and these contact points are connected to one another by a line. If the contact points are brought to different temperatures T _c and T _h , then a voltage U, which is given by, can be tapped between the contact points

U = (Qχ - Qγ) (T _c - T _h ),

where Qx and Qy are the so-called Seebeck coefficients of the different metals X and Y, which contact each other at the two contact points.

The Seebeck effect can thus be used to generate a voltage which, according to the invention, can be used to supply a circuit for the value or security document.

The Peltier effect is based on a reversal of the Seebeck effect and is also referred to as thermoelectric cooling. For this purpose, an electrical voltage is applied via the contact points of two different conductors A and B. placed. The voltage causes a temperature difference to occur between the contact points. The temperature difference T ₀ - Ti between the two contact points is as follows:

Where σ is the specific electrical conductivity, λ is the thermal conductivity and π _A and π _{B are} the Peltier coefficients of metals A and B.

According to the invention, such a Peltier element is used for converting electrical energy into thermal energy, so as to implement or address a security feature.

According to a preferred embodiment of the invention, this is done in such a way that the temperature of a bimetallic strip, which is printed on the value or security document, for example, is changed by means of the Peitier element. Due to the change in temperature, the different thermal expansion coefficients of the metals of the bimetallic strip lead to a bend in the bimetallic strip and thus to a deformation of the value or security document.

For example, such a bimetal strip can be printed lengthways on a banknote. As soon as the voltage source of the value or security document is switched on, a temperature difference is generated, which then causes the banknote to curl up due to the different coefficients of thermal expansion of the metals.

According to a further preferred embodiment of the invention, the temperature difference generated due to the Peltier effect is used for a color change. For this purpose, an area of the value or security document is printed with a thermochromic ink or a film with a thermochromic men dye applied. If the temperature changes due to the Peltier effect in the area of the thermochromic color, this leads to a color change of the thermochromic color pigments. This effect is visible to the naked eye; it is a so-called "public feature".

Preferred exemplary embodiments are explained in more detail below with reference to the drawings. Show it:

FIG. 1 shows a block diagram of an embodiment of a value or security document with a Seebeck element,

FIG. 2 shows a first embodiment of the value or security document from FIG. 1,

FIG. 3 shows a second embodiment of the value or security document of FIG. 1,

FIG. 4 shows a third embodiment of the value or security document of FIG. 1,

FIG. 5 shows an embodiment of a value and security document with a Peltier element,

FIG. 6 shows a partial view of an embodiment of the value or security document of FIG. 5 with a thermochromic color,

Figure 7 shows an embodiment of the value or security document of Figure 5 with a bimetal strip.

FIG. 1 shows a document 1. Document 1 is a value or security document, such as a bank note, a stamp, an identity card, passport, driver's license, label or the like chen. On the document 1 there is a printed circuit with an output or transmission unit 2 and an energy source 3.

The energy source 3 is a passive energy source that is used to convert thermal energy into electrical energy. The energy source 3 is preferably based on the so-called Seebeck effect.

For this purpose, the energy source 3 contains two contacts, which are each formed between two different metals. As soon as a temperature difference between the two contacts is generated by supplying thermal energy, the energy source 3 converts this thermal energy into an electrical voltage due to the Seebeck effect. This electrical voltage is applied to the output or transmission unit 2 via lines 4 and 5.

The output or transmission unit can be any security feature that requires electrical energy. The output or transmission unit 2 can be designed as a converter for converting the electrical energy supplied by the energy source 3 into another form of energy, such as light, sound or an electrical or magnetic field.

For example, the output or transmission unit has a light-emitting diode that emits visible light as soon as the energy source 3 supplies an electrical voltage. An organic light emitting diode is particularly suitable for this. The production of suitable organic light-emitting diodes (OLEDs) is known per se from "OLED Matrix Displays: Technology and Fundamentals", Polytronic 2001, Conference Procedings, October 21-24, 2001.

It is particularly advantageous here that OLEDs can also be printed on document 1 using various printing methods, for Example using inkjet printing, screen printing, letterpress printing, gravure printing or flat printing.

In a further embodiment, the output or transmission unit 2 is designed as an acoustic transducer. One possibility is the use of a so-called folding speaker. The production of a folding loudspeaker in film thickness is known per se from the prior art .http: //www.heise.de. Message from April 27, 2001 "Folding loudspeaker for your pocket").

Alternatively, the output or transmission unit 2 is designed as an electroluminescent component. For this purpose, electroluminescent dyes or pigments are applied to document 1. Such dyes can be excited in the electrical field and return to their basic state under light emission. Such an electroluminescent element can be realized according to the invention by printing on an electroluminescent dye. Alternatively or additionally, electrochromic dyes are used, which are also printed on or applied using thin foils.

Furthermore, polarization effects based on magnetic pigments can also be used to implement a security feature. The polarization of paramagnetic pigments is used in an electrical field. Alternatively, Liquid Christal Polymers (LCP) are used for this.

Alternatively, the output or transmission unit 2 can also have a coil for generating a magnetic field or a printed antenna in order to generate a field that can be detected from the outside.

A wide variety of physical and / or chemical conversion effects can therefore be used for the output or transmission unit 2 in order to at least convert at least part of the electrical energy supplied by the energy source 3 into another form of energy which is emitted by the output or transmission unit 2 in order to implement the security feature. The authenticity of the document 1 can be checked on the basis of the energy emitted by the output or transmission unit 2.

It is particularly advantageous to apply one or more elements of the circuit printed on the document 1 by means of printing ink in one printing step. For example, an electrically conductive printing ink is used to implement conductor tracks or other electrically conductive structures of the circuit.

An electrically conductive polymer, for example, is suitable as an electrically conductive printing ink. Such electrically conductive polymers are known per se from the prior art (cf. Hans Hofstraat “Will Polymer Electronics

Change the Electronics Industry? ", Polytronic 2001, Conference Proceedings).

The energy source 3 can also be implemented in terms of printing technology by printing on pastes of different metals, such as copper and silver conductive paste, for example.

The printing of at least parts of the circuit on the document 1 has the advantage that the circuit then forms an integral part of the document 1 and is particularly secure against manipulation. Furthermore, this also facilitates the handling of document 1, since it can be bent, bent or folded. This is particularly advantageous for banknotes and similar applications.

Paper or a plastic film is particularly suitable as a carrier material for document 1, to which the circuit is at least partially applied by printing technology. FIG. 2 shows in detail an embodiment of document 1 of FIG. 1. In the embodiment of FIG. 2, document 1 has an energy source 3 designed as a Seebeck element. For this purpose, a first metal is applied to document 1 in a strip-shaped area 6.

Adjacent to area 6 is a likewise strip-shaped area 7, to which a metal different from the metal of area 6 is applied. The area 7 is adjoined by a strip-shaped area 8, to which the same metal as the metal of the area 6 is applied. A suitable choice of the different metals is, for example, copper and silver.

In one embodiment, there is 1 copper conductive paste on areas 6 and 8 of the document, while silver conductive paste is located on area 7. However, the invention is not restricted to a specific choice of metals; the Seebeck effect basically works if two different metals are selected.

The metal paste of the area 6 thus forms a contact area 9 with the metal paste of the area 7 and the metal paste of the area 7 forms a contact area 10 with the metal paste of the area 8. The temperature Ti prevails at the contact area 9 and the temperature prevails at the contact area 10 Temperature T ₂ . If there is no external influence, these temperatures Ti and T ₂ are essentially equal to the ambient temperature. In this case, no voltage is generated by the energy source 3.

By placing a finger 11 of a user of the document 1 on the contact surface 9, thermal energy is supplied there when the temperature of the finger (approx. 36 °) is higher than the ambient temperature.

There is then a temperature Ti of approximately 36 °, while the temperature T _{2 is,} for example, 20 ° room temperature. Because of this temperature difference, the energy source 3 generates because of the sea Beck effect is a voltage which is applied to the output or transmission unit 2 via lines 4 and 5.

In the exemplary embodiment considered here, the output or transmission unit 2 has an electroluminescent or electrochromic color 12, which changes color when the voltage supplied by the energy source 3 is applied or when the corresponding thermal current flows.

Depending on the color 12 used, this color change can be permanent or self-reversible. In the former case, the color change is retained even if the finger 11 is removed from the contact surface 9 and the energy source 3 can no longer supply thermal voltage. In the second case, after the finger 1 is removed from the contact surface 9, the color 12 changes again to the starting color.

If the color change is not self-reversible, such a color change back to the original color can be provoked by removing the finger 11 from the contact surface 9 and instead placing it on the contact surface 10, so that the energy source is at a thermal voltage of the same level provides opposite polarity. This opposite polarity then causes the color 12 to return to its original color through a color change.

An alternative use of document 1 in FIG. 2 is shown in FIG. 3. With this use of document 1, two different thermal energy sources are used, namely finger 11 and another external energy source 13, which supplies thermal energy. With the external energy source

13 can be, for example, a laser that emits a laser beam

14 for applying a temperature.

The two thermal energy sources, that is to say the finger 11 and the external energy source 13, serve to determine a temperature difference between the To produce contact surfaces 9 and 10, which is largely independent of the ambient temperature. For this purpose, the finger 11 is placed on the contact surface 9, so that the temperature T-ι of approximately 36 ° C. is established there.

On the other hand, the contact surface 10 is irradiated with a defined energy by the laser beam 14, so that a certain temperature T _{2 is} established there. Because of this, the energy source 3 supplies a thermal voltage which is essentially independent of the ambient temperature, so that the security feature implemented by the output or transmission unit 2 can be checked under all circumstances.

In a further exemplary embodiment, the structure of the value or security element described with reference to FIG. 3 can also be used in two stages. In a first stage, only the finger is placed on the contact surface 9, so that the temperature Ti is established there. Analogous to the exemplary embodiment described with reference to FIG. 2, the second contact surface has ambient temperature. This temperature difference causes a first thermal voltage, which is present at the output and transmission unit 2 and, for example, produces a first color change. In a second stage, as described above, the energy source 13 is now directed onto the contact surface 10, so that a temperature T _{2 is} established there. Ambient temperature is present on the other contact surface. This results in a second temperature difference, which generates a second thermal voltage, which is also present at the output and transmission unit 2 at this stage. This second thermal voltage could, for example, cause a second color change in the output and transmission unit 2, which can then be detected, for example, by machine.

FIG. 4 shows another possible use of document 1 in FIG. 2. In this case there is a defined temperature difference between the temperature Ti of the contact surface 9 and the temperature T _{2 of} the contact surface 10 only produced by the external energy source 13. For this purpose, the external energy source 13 is again preferably designed as a laser.

The laser beam 14 then alternately sweeps over the contact surfaces 9 and 10 in rapid succession, the average residence time of the laser beam 14 on the contact surface 9, for example, being shorter than on the contact surface 10, so that the temperature Ti is lower than the temperature T ₂ . The temperature difference can thus be set via the difference between the average dwell times of the laser beam 14 on the contact surface 9 and the contact surface 10 in order to arrive at a defined thermal voltage of the energy source 3 which is independent of the ambient temperature.

FIG. 5 shows a block diagram of a document 16, which in turn is designed as a value or security document. Document 16 has an energy source 17, which is an active or a passive energy source.

A printed battery, for example, is suitable for realizing an active energy source. Such a printed battery is preferably produced by means of multi-layer printing of electrically active substances, such as, for example, lithium polymers.

According to a further preferred embodiment, the energy source is a passive energy source, such as a solar cell or an antenna.

Solar cells can be applied to the carrier layer on the one hand via very thin foils or on the other hand by using printing processes known per se (cf. Plastic Solar Cells ", Adv. Funct. Mater. 2001, 11, No. 1, February, page 15 to 26). The energy source 17 is connected to the output or transmission unit 20 via the lines 18 and 19. In the exemplary embodiment shown, line 19 is interrupted in order to implement a switch.

The output or transmission unit 20 contains a Peltier element 21 for supplying a security feature 22 with thermal energy. The security feature 22 includes a converter that converts the thermal energy supplied by the Peltier element 21 into another form of energy that is perceivable from the outside due to a physical and / or chemical effect.

To check the security feature 22, the interruption of the line 19 is closed, for example by a user holding a coin over the interruption in order to close the circuit. The Peltier element 21 is then supplied with voltage by the energy source 17, so that a temperature difference arises between the contact surfaces of the Peitier element. This temperature difference is used to supply the security feature 22 with thermal energy, so that it is activated. As a result, the authenticity of the document 16 can be checked.

FIG. 6 shows a schematic view of an embodiment of the document 16 in section. The document 16 has a carrier 23, which consists for example of paper or plastic. A metal paste 24, for example with copper particles, is printed on the carrier 23, as is a metal paste 25 with a metal other than copper, such as silver. The metal pastes 24 and 25 form contact surfaces 26 and 27.

This arrangement of the metal pastes 24 and 25 realizes the Peltier element 21 (see FIG. 5), which is supplied with voltage via the lines 18 and 19 as soon as the interruption of the line 19 is closed and the energy source 17 is one Delivers tension. As soon as a voltage is present, the temperatures at the contact surfaces 26 and 27 change in opposite directions, that is to say, for example, the temperature at the contact surface 26 decreases by a certain amount, while the temperature of the contact surface 27 increases by the same amount.

The security feature 22 in the form of thermochromic paint 28 is applied above the contact surface 26. The thermochromic color 28 changes its color when the temperature changes at the contact surface 26. In a further exemplary embodiment, such a thermochromic color can also be applied over the contact surface 27, which changes to a different color due to the lowering of the temperature.

FIG. 7 shows an alternative embodiment of the document 16 of FIG. 6. In the embodiment of FIG. 7, the security feature 22 (cf. FIG. 5) is implemented by a bimetal strip. This consists of a metal strip 29 and a metal strip 30. The metal strip 29 is located above the contact surface 26, while the metal strip 30 is located above the contact surface 27.

If an electrical voltage is applied via the lines 18 and 19, the temperature at the contact surface 26 increases, for example, while it decreases at the contact surface 27 by the same amount. As a result, the metal strip 30 contracts, while the metal strip 29 expands. This creates a mechanical tension that deforms the document 16. For example, the document 16 curls up as soon as the electrical voltage is applied.

Alternatively, the metal strips 29 and 30 are arranged one above the other and over the same contact surface 26 or 27. Then both metal strips 29 and 30 are heated or cooled to the same temperature. The metal strips 29 and 30 have metals with different coefficients of thermal expansion. Due to the different coefficients of thermal expansion in this case too, a mechanical tension which leads to the deformation of the document 16.

In a further exemplary embodiment of the invention, at least some of the elements located on the value or security document and described above have at least partially an overlying protective layer which protects the elements from environmental influences. Such a protective layer can be partially transparent and / or insulating. The protective layer can consist, for example, of a plastic. The protective layer can be applied to the value or security document by an additional printing step or by laminating. In the case of a configuration analogous to the exemplary embodiment which was described with reference to FIG. 5, the protective layer has openings so that the interruption and the ends of the line 19 which form the interruption can be exposed and make contact.

The above-mentioned exemplary embodiments of the invention can be used to implement both public feature security features and machine-readable security features. It is even possible to arrange both types of security features within one security feature.

LIST OF REFERENCE NUMBERS

Document 1

Output or sending unit 2

Energy source 3

Line 4

Line 5

Area 6

Area 7

Area 8

Contact area 9

Contact area 10

Fingers 11

Color 12 external energy source 13

Laser beam 14

Document 16

Energy source 17

Line 18

Line 19

Output or transmission unit 20

Peltier element 21

Security feature 22

Carrier 23

Metal paste 24

Metal paste 25

Contact area 26

Contact surface 27 thermochromic color 28

Metal strips 29 Metal strips 30

Claims

Patent claims

1. Value or security document with a circuit (2, 3, 4, 5) and with means (3, 6, 7, 8) for converting thermal energy into electrical energy for supplying the circuit.

2. Value or security document according to claim 1, wherein the means for conversion are designed as a Seebeck element.

3. A value or security document according to claim 2, wherein the Seebeck element has a first area (6) with a first metal, a second area (7) with a second metal and a third area (8) with the first metal, wherein there is contact between the first and the second area and between the second and the third area.

4. A value or security document according to claim 3, wherein the first metal is copper and the second metal is silver.

5. Value or security document according to one of the preceding claims 1 to 4, wherein the means for conversion preferably have a carrier made of paper or plastic film.

6. Value or security document according to one of the preceding claims 1 to 5, wherein the means for conversion are printed on the value or security document.

7. Value or security document according to one of the preceding claims 1 to 6, wherein one or more elements of the circuit are printed by means of a printing ink.

8. Value or security document according to one of the preceding claims 1 to 7, wherein the circuit has at least one component for realizing a security feature.

9. Value or security document according to claim 8, wherein the component is designed as a converter to convert the electrical energy into another

To convert energy form, in particular electromagnetic radiation, sound or an electrical or a magnetic field.

10. Value or security document with means (21) for converting electrical energy into thermal energy and with a security feature

(20,22), which is supplied by the thermal energy.

11. Value or security document according to claim 10, wherein the means for conversion are designed as a Peltier element (21).

12. The value or security document according to claim 11, wherein the Peltier element has a first area with a first metal, a second area with a second metal and a third area with the first metal, wherein between the first and the second area so- how there is contact between the second and the third area.

13. A value or security document according to claim 11 or 12, wherein the first metal is copper and the second metal is silver.

14. Value or security document according to claim 11, 12 or 13, wherein the means for conversion and / or one or more other elements (17, 18, 19) of the circuit are printed on the value or security document.

15. Value or security document according to one of the preceding claims 10 to 14 with an energy source (17) for the electrical energy, wherein the energy source is preferably a battery, a solar cell or an antenna.

16. Value or security document according to one of the preceding claims 10 to 15 with a switch for checking the security feature.

17. Value or security document according to claim 16, wherein the switch is realized by an interruption of a conductor track (19).

18. Value or security document according to one of the preceding claims 10 to 17, wherein the security feature has an arrangement (29, 30) which is designed to deform the value or security document due to the thermal energy, the arrangement preferably being a bimetallic strip.

19. Procedure for producing a value or security document with the following steps:

- provision of a carrier,

- Application of a first metal in a first area (6), a second metal in a second area (7) and the first metal in a third area (8), so that between the first and the there is contact in the second area and between the second and third areas

20. The method according to claim 19, wherein an electrical and / or an electronic circuit is applied to the carriers.

21. The method according to claim 19 or 20, wherein one or more elements of the circuit are applied by printing.