EP1936603A1 - Sicherheitsdokument mit elektrochromem Bauteil - Google Patents

Sicherheitsdokument mit elektrochromem Bauteil Download PDF

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Publication number
EP1936603A1
EP1936603A1 EP06026309A EP06026309A EP1936603A1 EP 1936603 A1 EP1936603 A1 EP 1936603A1 EP 06026309 A EP06026309 A EP 06026309A EP 06026309 A EP06026309 A EP 06026309A EP 1936603 A1 EP1936603 A1 EP 1936603A1
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EP
European Patent Office
Prior art keywords
security document
electrochromic
document according
electrochromic element
electrolyte
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP06026309A
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English (en)
French (fr)
Inventor
Andreas Georg
Franz Brucker
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European Central Bank
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European Central Bank
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Filing date
Publication date
Application filed by European Central Bank filed Critical European Central Bank
Priority to EP06026309A priority Critical patent/EP1936603A1/de
Publication of EP1936603A1 publication Critical patent/EP1936603A1/de
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/20—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof characterised by a particular use or purpose
    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
    • G07D7/00—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency
    • G07D7/14—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency using chemical means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/20—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof characterised by a particular use or purpose
    • B42D25/29—Securities; Bank notes
    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
    • G07D7/00—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency
    • G07D7/01—Testing electronic circuits therein
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/36—Identification or security features, e.g. for preventing forgery comprising special materials
    • B42D25/378—Special inks
    • B42D25/382—Special inks absorbing or reflecting infrared light
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/36—Identification or security features, e.g. for preventing forgery comprising special materials
    • B42D25/378—Special inks
    • B42D25/387—Special inks absorbing or reflecting ultraviolet light

Definitions

  • the present invention relates to a security document, particularly a banknote comprising an electrochromic element as an electronic security means.
  • security means for security documents have been developed and are being developed to allow users and/or machines to distinguish between genuine and forged security documents and/or to discriminate among different kind of security documents.
  • EP-A-1 431 062 discloses a banknote comprising on-board electrical power supply means for driving a new class of electronic security means utilizing on-board power supply.
  • the electronic security means are means comprising a microchip, electroluminescent materials, electro-active polymers/materials, light-emitting diodes and polymeric electronic displays.
  • the security means as disclosed in EP-A-1 431 062 and WO 00/07151 have some very important disadvantages.
  • the electrical power supply means and the microchips are widespread. Therefore, such elements are easily available.
  • these elements will cause enormous costs.
  • the lifetime of the electric power supply means, the security means and the security document, especially the banknotes comprising these elements are limited, respectively.
  • Electrochromic paper utility of electrochromes incorporated in paper Electrochimica Acta 46 (2001) 2195 - 2202 teaches that the electrochemistry of electrochromic paper is similar to that of electrochromes without the paper.
  • An electrochromic paper can be obtained by dispersing an organic or inorganic electrochrome in a paper. An image is generated when a stylus electrode touches it, generating an electrochromic image. Possible applications of the electrochromic paper comprise viable paper products having security implications, such as tickets, vouchers and banknotes, wherein the electrochromic paper product is merely placed between two electrodes and a voltage applied. Visual inspection for the formation of colour confirms (or otherwise disproves) the genuineness of the product.
  • an electrochromic paper of that kind comprise the low contrast achievable; the limited long-term stability of the electrochromic paper because the electrochrome is directly exposed to the environment and because of the high voltages, which are needed to operate the electrochromic paper, the comparatively simple structure making it easy to counterfeit the paper, and the comparatively long time needed for carrying out a testing cycle, i. e. colouring and bleaching of the electrochromic image.
  • a security feature which is difficult to counterfeit, which can be applied on flexible substrates, preferably banknotes, and which can be tested by means of a simple power supply machine together with an human operator.
  • the security feature should be thin, preferably thinner than 100 ⁇ m, more preferably below 50 ⁇ m, and allow a short testing cycle, preferably shorter than thirty seconds, more preferably shorter than 10 seconds, especially shorter than 5 seconds.
  • the security feature should have high long-term stability and its production should be possible in a simple and cost efficient way.
  • the present invention provides a security document with a new kind of a reversible security feature
  • security document refers to all kind of documents that contain at least one feature that can be used to prevent counterfeiting by providing authentication, identification, verification and/or classification of the document.
  • they include banknotes, passports, chequebooks, identity cards, credit cards and/or debit cards, wherein banknotes are especially preferred.
  • the security document comprises an electrochromic element.
  • Elements of that kind are known in the art and usually contain at least one electrochromic material.
  • the electrochromic material changes its colour upon oxidation or reduction reversibly.
  • Preferred classes of electrochromic materials comprise a pair of redox substances, which form coloured, positively or negatively charged, chemically reactive free radicals after reduction or oxidation.
  • the pair of redox substances preferably used is in each case a reducable and oxidizable substance. Both are preferably colourless or have only a slight colour. Under the action of an electric potential, one substance is reduced and the other is oxidized, at least one becoming coloured.
  • electrochromic materials in parallel to the electron injection and extraction, which causes the reversible colour change, an injection and extraction of positive ions, like protons or Li + takes place.
  • positive ions like protons or Li +
  • the two original redox substances can be reformed with their coloration or lightening of colour occurring.
  • Electrochromic substances particularly suitable for the purposes of the present invention are tungsten oxide, niobium oxide, titanium oxide, iridium oxide, nickel oxide, molybdenum oxide, antimon-tin oxide, prussian blue, polyaniline, polythiophene, viologene, polypyrrole, iodide or mixtures of two or more of these materials.
  • Preferred polythiophene compounds are 3,4 polyethylene dioxythiophene (PEDOT) and poly(3,4-ethylenedioxythiophene-didodecycloxybenzene) (PEB).
  • the electrochromic element may comprise a second redox couple, which can be considered as an ion-storage component or as a redox couple in form of ions, which are comprised in an electrolyte as mentioned above.
  • This second redox couple may be electrochromic by itself. Therefore, the materials described above as electrochromic substances may be used.
  • Particularly useful components for a redox couple in form of ions dissolved in a solvent are iodide/triodide, bromide/tribromide or fluoride/trifluoride.
  • the electrochromic element of the present invention comprises at least two electrodes, at least one electrolyte and at least one electrochromic material.
  • the electrode is the area, which conducts the electrons parallel to the substrate from the power supply points to the different locations of the electrochromic material.
  • it may be formed of transparent conducting materials, as will be described below, or of non-transparent materials, like metals. A high conductivity is desired to allow short switching times. Therefore, the sheet resistance of a square geometry is preferably below 1 k ⁇ , more preferably below 100 ⁇ .
  • electrolyte refers to a substance containing free ions, which behaves as an electrically conductive medium. It is not limited to ionic solutions, i. e. ions in solutions, but also comprises ionic liquids (molten electrolytes) and solid electrolytes.
  • the specific conductivity of the electrolyte at 20°C is preferably greater than 0.1 mS/cm.
  • the vapour pressure of the electrolyte at 20°C is preferably lower than 0.1 Pa.
  • the electrolyte comprises a redox salt, like lithium iodide, optional together with additional iodide and/or iodine.
  • the solubility of this redox salt in the electrolyte is preferably at least 0.01 mol/l, more preferably at least 0.1 mol/l at 25°C.
  • Particularly suitable ionic liquids are present in the form of a liquid at 20°C and preferably have a dynamic viscosity, measured at 20°C at 1 Hz, of 1000 mPas or less.
  • the electrodes enclose the electrochromic material and the electrolyte and protect them from the environment. At least one of the electrodes preferably has a light transmittance allowing to see through. Its transparency at 550 nm is preferably at least 25 %, more preferably at least 50 % and most preferably at least 75 %.
  • the transparent electrodes preferably comprise a chemically inert support material, such as glass or a polymer substrate, which preferably has a thickness not exceeding 50 ⁇ m, more preferably not exceeding 30 ⁇ m.
  • polymer foils such as PET foils, is particularly preferred in that context.
  • the electrodes preferably comprise a transparent electronically conducting layer.
  • Such layers are known in the art. These layers preferably comprise highly doped metal oxides, such as SnO 2 :F, SnO 2 :Sb, In 2 O 3 :Sn (ITO), Cd 2 SnO 4 , ZnO:Al and ZnO:In.
  • the electrochromic material is dissolved in the electrolyte.
  • a particular suitable example of that kind is an electrochromic element having the so-called “solution setup", i. e. an electrochromic element comprising the following layers in the following order:
  • the electrochromic material undergoes an electron-transfer reaction on the surface of the first electrode, and changes its colour. On the counter electrode, a similar or different reaction takes place.
  • a preferred example comprises methyl viologen in water as electrochromic electrolyte solution.
  • the electrochromic element comprises a first electrochromic layer between the first electrode and an electrolyte layer.
  • a particular suitable example of that kind is an electrochromic element having the so-called “solution-to-solid setup", i. e. an electrochromic element comprising the following layers in the following order:
  • an electrochromic layer is formed during the colouring or bleaching cycle as a consequence of a redox reaction on the electrolyte-electrode surface (example: heptyl viologen), or it may be a fixed electrochromic layer, like WO 3 , which changes its colour upon electron and ion (e. g. H + or Li + ) uptake from the electrolyte.
  • a second redox reaction takes place, which is favourably catalysed by a thin Pt layer.
  • the electrochromic element comprises a first electrochromic layer between the first electrode and an electrolyte layer and a second electrochromic layer between the electrolyte and the second electrode.
  • a particular suitable example of that kind is an electrochromic element having the so-called “battery setup", i. e. an electrochromic element comprising the following layers in the following order:
  • ions e. g. H + and Li +
  • H + and Li + are shifted from the first electrochromic layer to the second electrochromic layer and vice versa, similar to the charging and decharging of a battery.
  • the electrochromic layers are again formed during the colouring or bleaching cycle as a consequence of a redox reaction on the electrolyte-electrode surface, or may be fixed electrochromic layers, which changes its colour upon electron and ion (e. g. H + or Li + ) uptake from the electrolyte.
  • the use of the "solution-to-solid setup" with just one electrochromic layer has proven of particular advantage, since the problem of precharging the electrochromic device can be avoided.
  • a “battery setup” needs a method to create a first charge in the device before it can be shifted between the electrodes.
  • the “solution-to-solid setup” solves this problem, as the charge is present from the beginning in the electrolyte.
  • the security document comprises an electrochromic element, in which one electrode is at least partially coated with an electrochromic material and the other electrode is at least partially coated with a catalytic layer, and wherein the electrolyte comprises at least one redox salt.
  • the electrolyte comprises an iodide, bromide or fluoride and positive ions of the first group of the periodic table of elements, in particular H + or Li + .
  • the outer surface of the electrochromic element is preferably at least partially covered with a support material.
  • a support material Preferably at least 50 % of the total outer surface, more preferably at least 75 % of the total outer surface, and most preferably the entire outer surface are/is covered with a support material.
  • the support material is not particular restricted and, in principle, can be chosen freely from papers, polymer foils, e. g. polyethylene terephthalate foils, and similar materials. However, it has proven of particular advantage to use materials with a low water and oxygen permeability to increase the long-term stability of the electrochromic element.
  • thin polymer foils having a thickness of less than 50 ⁇ m, preferably less than 25 ⁇ m, and comprising a barrier coating on one side, such as SiO 2 or Al 2 O 3 and an additional barrier coating on the other side, which simultaneously acts as an transparent electrode of the electrochromic cell, such as ITO.
  • this layer is deposited by sputtering or evaporation, as this leads to good barrier properties.
  • the electrochromic element comprises a reflector layer, more preferably a reflecting electrode, reflecting substrate, a reflecting support or a reflecting electrolyte.
  • Preferred reflector layers have a white colour and do essentially not attack the organic substances contacting the reflector layer or disturb the ionic or electronic conductivity.
  • Particular useful materials are ZnO and TiO 2 . These may be printed onto the substrates or dispersed in the electrolyte in form of small particles with typical sizes of 10 ⁇ m down to 10 nm, preferably 1 ⁇ m down to 100 nm.
  • a reflector layer the visibility of the colour change of the electrochromic element can be further improved.
  • the printed symbols may be any symbol, which shows a high resolution, which is difficult to incorporate in the electrochromic device, e. g. by applying a reflecting electrolyte or a reflecting electrode.
  • the electrochromic material and/or the catalytic material is designed as a symbol, for example by using masks during the deposition process, or by etching processes or by a printing process. This also makes it more difficult to counterfeit the device.
  • the electrochromic element is flexible. Flexibility means that the electrochromic element can be bend with a radius of curvature of 5 cm, more preferably 1 cm, most preferably 0.5 cm. The radius is measured according to the "simple support ends" method, top part of fig. 5, in " A mechanical assessment of flexible optoelectronic devices", Zhong Chen, Braina Cotterell, Wei Wang, Ewald Guenther, Soo-Jin Chua, Thin Solid Films vol. 394, pages 202-206 of the year 2001 .
  • the electrochromic element preferably comprises a bend protection.
  • Bend protection means that the security document, especially a banknote can be bended without destroying the electrochromic element.
  • a bend protection can be achieved by a stable metal frame surrounding the electrochromic element or a metal sheet below the element.
  • the bend protection may be achieved by producing a electrochromic element having a small dimension. Preferably, the maximum dimension of the electrochromic element does not exceed 3 cm.
  • the switching time of the coloration of the electrochromic element i. e. the time needed to switch the electrochromic element from the bleached state to the coloured state is preferably short.
  • the switching time of the electrochromic element is preferably below thirty seconds, more preferably below 10 seconds and most preferably below 5 seconds.
  • the switching time is defined as follows: For the colouring process, the security document is connected to a power source with voltages below 3V, wherein the use of 1.5V is particularly preferred. Then the change in the visual reflectance is measured.
  • the "switching time” is defined here to be the time, in which 63% of the total change of the visual reflectance is reached.
  • the switching time of the electrochromic element can be further improved by using an assembly, wherein in a top view at least one of the electrodes, and more preferably both electrodes, has (have) a greater surface than the electrochromic layer.
  • This special geometry reduces the effective resistance and in consequence, the switching time.
  • the charge and in consequence for a determined switching time the current is proportional to the area of the electrochromic layer. As the current defines the ohmic voltage losses, and the voltage is limited for keeping the device stable, a small area of the electrochromic layer is helpful for a limitation of the voltage.
  • the surface of at least one electrode, more preferably of both electrodes is at least 25% greater than, more preferably at least 50% greater than, even more preferably at least 100% greater than and most preferably at least 200% greater than the surface of the electrochromic layer in the top view.
  • a ratio of electrode surface : electrochromic layer surface in the range of 2:1 to 20:1 has proven of particular advantage.
  • the quality of the security document can be further improved by using two or even more electrochromic elements.
  • the electrochromic elements preferably have different switching times to make counterfeiting even more difficult.
  • the bleaching time of the electrochromic element i. e. the time needed to switch the electrochromic element from the coloured state to the bleached state is preferably short.
  • the bleaching time of the electrochromic element is preferably below thirty seconds, more preferably below 10 seconds and most preferably below 5 seconds.
  • the switching time for the bleaching process is defined as the time, in which 63% of the total change of the visual reflectance is reached after switching of the illumination.
  • the bleaching and/or the coloration time can be adjusted by the use of catalysts accelerating the reaction kinetics.
  • Useful catalysts are Pt, Pd, Ni, Au, Os, Re, Ir, Ru, and Rh.
  • the catalyst can be arranged as a separate layer, for example, onto a layer, which comprises an electrochromic material, or onto a transparent electronically conducting layer. If these layers are made in such a way, that they are porous, the catalyst can also be arranged below these layers. Furthermore, the catalyst can be arranged as an additive in the electrolyte.
  • electrochromic elements can be found in Pail S. Monk, Roger J. Mortimer, David S. Rosseninsky “Electrochromism: Fundamentals and Applications", VCH Weinheim, 1995 , or in C.G. Granqvist, "Handbook of inorganic electrpchromic materials", Elsevier Science B.V. Amsterdam, 1995 which is incorporated herein by reference.
  • the security document comprises at least two power supply points each electronically connected to the electrochromic element, but electronically isolated from each other.
  • the present invention distinguishes between two kinds of charge transport: charge transport by electrons and by ions.
  • the first shall be referred as “electronical” and the second as “ionical”.
  • the term “electronical connection” refers to a connection via a material preferably having a resistivity ⁇ of less than 10 -1 ⁇ ⁇ cm, very preferably of less than 5*10 -3 ⁇ ⁇ cm, when measured at 25°C.
  • two articles will be “electronically isolated one from another” if there is no electronical connection between the articles, in particular via a material having a resistivity ⁇ of less than 10 2 ⁇ ⁇ cm, when measured at 25°C.
  • the material of the power supply points used in the present invention preferably comprise an electrically conductive material preferably having a resistivity ⁇ of less than 10 -1 ⁇ ⁇ cm, very preferably of less than 10 -3 ⁇ ⁇ cm, when measured at 25°C.
  • Particular suitable materials are metals, such as silver, gold, aluminium, messing, iron, chromium, and stainless steel.
  • the surfaces of the power supply points are preferably left exposed to the environment. In such circumstances, it will be apparent to those skilled in the art that materials will be preferably chosen that suffer minimal tarnishing or corrosion during everyday use of the secure document.
  • the power supply points are each electronically connected to the electrochromic element, preferably via one or more electronically conducting tracks.
  • the electronically conducting tracks can be made of any electronically conducting material, but preferably have a resistivity ⁇ of less than 10 -1 ⁇ ⁇ cm, very preferably of less than 5* 10 -3 ⁇ ⁇ cm, when measured at 25°C.
  • a sealing is added, which encloses an inner area, which comprises electrolyte, electrochromic material, and not wholly the electrodes.
  • the power supply points are preferably outside of this inner area, and the electrodes electronically connect the power supply points optionally via additional electronically conducting tracks with the inner area.
  • the sealing is applied by a thermal step, like welding of the supporting material or application of a hot melt, which does not destroy the conductivity of the electrodes, especially the electronical contact from the inner area to outside of the inner area.
  • the security document of the present invention is preferably adapted for checking its authenticity by electronically connecting the power supply points to a power source and observing a status change of the electrochromic element, preferably a change in the optical status.
  • the positions of the power supply points and of the electrochromic element on the security document can principally be chosen freely. It is merely important that the power supply points are electronically isolated from each other and that they are electronically connected to the electrochromic element so that a reversible status change of the electrochromic can be induced by connecting the power supply points to a power source.
  • the electrochromic element is preferably located nearby a color reference to ease the visibility of a correct color change of the electrochromic element.
  • a color reference may comprise different tints, which the electrochromic element passes through.
  • the kind of the substrate means used in the present invention is not critical. However the use of substrate means comprising paper, plastic, polymer, elemental metallic foils, metallic alloy foils and/or synthetic paper is preferred.
  • the security document of the present invention is comparatively thin and its thickness is preferably smaller than 100 ⁇ m.
  • the overall thickness of the power supply points, not including the substrate thickness is between approximately 10 to 50 ⁇ m.
  • the thickness of the interconnects between the power source and the electrochromic element is preferably within the range from approximately 1 to 30 ⁇ m.
  • the thickness of the electrochromic element, not including the substrate means is preferably in the range from 10 to 100 ⁇ m.
  • the substrate means is preferably provided with the power supply points and the electrochromic element, wherein the power supply points and the interconnects are preferably printed onto the substrate and the complete electrochromic element is preferably subsequently attached to the substrate.
  • electronical connection will be made by ensuring that exposed printed power supply points on the substrate align with power supply points on the electrochromic element.
  • the power supply points, optionally the interconnects, and the electrochromic element is preferably arranged together in one element, which is then attached to the substrate means.
  • the conducting tracks and/or the power supply points are deposited onto the substrate using an electroless deposition technique.
  • an electroless deposition technique specially formulated catalytic ink is printed onto the substrate in a desired pattern.
  • the substrate is then immersed in a chemical solution containing ions of the metal to be deposited. Over time, electroless deposition of the metal onto the substrate areas printed with catalytic ink occurs.
  • This technique is advantageous compared to other methods for producing the desired electrically conducting tracks and the power supply points, such as printing of metal-loaded inks, since the technique produces deposited material with a density that is very close to that of the bulk material. Furthermore, this technique is advantageous over standard printing of loaded inks in that the adhesion of the deposited material to the substrate is superior.
  • the aforementioned electroless deposition technique is described in detail in Patent Application WO 02/099163 and is suitable for a range of substrates (such as polyester, polypropylene, synthetic paper, fine-weave cloths and polycarbonate) and a range of deposited metals (including copper, nickel, cobalt, iron, tin and a variety of magnetic and non-magnetic alloys).
  • substrates such as polyester, polypropylene, synthetic paper, fine-weave cloths and polycarbonate
  • deposited metals including copper, nickel, cobalt, iron, tin and a variety of magnetic and non-magnetic alloys.
  • the present invention does not preclude other methods of depositing electrically conducting materials.
  • Other methods include printing (such as screen printing and gravure printing) of particle-loaded inks, electroplating methods, chemical vapour deposition, sputtering, evaporation and etch-resist methods, all of which are known to those skilled in the art.
  • the manufacture of the electrochromic element can be achieved in a conventional manner.
  • the electrochromic layer, the preferably transparent conducting layer, the metallic conducting layers, and/or the catalytic layer are preferably prepared by deposition techniques, more preferably by physical vapour deposition (PVD), which includes magnetron sputtering and evaporation.
  • PVD physical vapour deposition
  • masks can be used to allow the preparation of specific shapes, area ratios and symbols.
  • the space between the electrodes is preferably filled with the electrolyte and the electrochromic element is sealed to avoid leakage, evaporation or impurification of the components.
  • Said sealing is preferably achieved by encapsulating the electrolyte, the electrochromic material and part of the electrodes in a suitable support material, such as a polymeric film or a flexible glass foil, wherein the support material preferably has high oxygen and/or water barrier properties.
  • the sealing is preferably achieved by a heating step, preferably by welding the electrodes together, wherein the electronically conducting layer is preferably not destroyed.
  • At least two electrodes each comprising a support layer, preferably a PET foil, and an electronically conducting layer, preferably an ITO-layer, are placed in front of each other in a way, that the electronically conducting layers look at each other. At least one of these electronically conducting layers is provided with an electrochromic layer. Thereafter, an electrolyte, preferably comprising a redox couple, is applied onto one of the electronically conducting layers, for example by printing or means of a microdispenser. Then, the other electrode is applied onto this, followed by an application of a sealing, for example by using a hot melt or melting the substrates together.
  • the power supply points are electrically connected to a power source and a status change of the electrochromic element is observed.
  • a voltage below 3V, more preferably below 1.5V, is preferably used.
  • the quality of verification can be further increased by simultaneously measuring optical and electrical properties of the electrochromic element and/or by measuring changes of optical and/or electrical properties of the electrochromic element with time.
  • FIG. 1 shows a schematic top view of a first particularly preferred electrochromic element, which has been opened in the middle.
  • the element comprises a first and a second electrode comprising a first and a second support layer (1, 3), e. g. a PET foil, on top of which a first and a second electronically conducting layer (5, 7), e. g. ITO, are located.
  • Each of the electrodes also comprises a power supply point (11, 13).
  • the electrodes are mechanically connected to each other by a sealing (19).
  • Said sealing (19) can be achieved by the use of a suitable sealing material, such as an inert polymer material, or by welding together the different layers of the electrochromic element.
  • the sealing (19) encloses an inner area (21) which is preferably filled with an electrolyte.
  • This electrolyte preferably contains a redox couple, e.g. iodide and triodide.
  • the inner area of the first electrode comprises an image made of electrochromic material (9), e.g. tungsten oxide, which is placed on top of the first electronically conducting layer (5) and only covers a small area of the first electrically conducting layer (5) in order to ensure a comparatively short switching time.
  • the inner area of the second electrode i. e. the area of the second electrode, which is enclosed by the sealing (19), partially comprises the second electronically conducting layer, which is at least partially covered with a catalytic layer (17), such as Pt.
  • both electronically conducting layers (5, 7) extend to opposite directions and merely overlap in the middle, i. e. the inner area of the second electrode.
  • the design avoids carefully that there are locations, where first and second electrode and sealing fall together, as this should lead to short circuits.
  • Both power supply points (11, 13) are easily accessible, since they are not covered neither by the opposite electrode (7, 5) nor by the opposite substrate layer (3, 1).
  • the second electrode (7) and the second substrate layer (3) comprise a hole (15) at the location of the second power supply point (13), so that the second power supply point (13) is also easily accessible from the same side as the first power supply point (11).
  • FIG. 2 shows a schematic top view of a second particularly preferred electrochromic element, which has been opened in the middle.
  • the element comprises a first and a second electrode comprising a first and a second support layer (101, 103), e. g. a PET foil, on top of which a first and a second electronically conducting layer (105, 107), e. g. ITO, are located.
  • the first substrate layer (101) comprises an extension of the second electrode (106), which is electronically connected to the second electrode (107) via a welding (120) and which is electronically isolated from the first electrode (105).
  • the first electrode and the extension of the second electrode (106) each comprise a power supply point (111, 113).
  • the electrodes are mechanically connected to each other by a sealing (119).
  • Said sealing (119) can be achieved by the use of a suitable sealing material, such as an inert polymer material, or by welding together the different layers of the electrochromic element.
  • the sealing (119) encloses an inner area (121), which is preferably filled with an electrolyte.
  • This electrolyte preferably contains a redox couple, e.g. iodide and triodide.
  • the inner area of the first electrode comprises an image made of electrochromic material (109), e.g. tungsten oxide, which is placed on top of the first electronically conducting layer (105) and only covers a small area of the first electronically conducting layer (105) in order to ensure a comparatively short switching time.
  • the inner area of the second electrode i. e. the area of the second electrode, which is enclosed by the sealing (119), partially comprises the second electronically conducting layer (107), which is at least partially covered with a catalytic layer (117), such as Pt.
  • both electronically conducting layers (105, 107) extend to opposite directions and merely overlap in the middle, i. e. the inner area of the second electrode. Again, the design avoids carefully that there are locations, where first (105) and second electronically conducting layer (107) and sealing (119) fall together, as this should lead to short circuits.
  • the second power supply point (113) is connected to the second electrode (107) via an additional melting step, for example by melting the two substrate layers together in form of a ring (120).
  • the same technology can be applied as for the sealing ring (119).
  • Both power supply points (111, 113) are easily accessible from the top, since they are not covered neither by the opposite electrode (107) nor by the second substrate layer (103).

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Business, Economics & Management (AREA)
  • Accounting & Taxation (AREA)
  • Finance (AREA)
  • Electrochromic Elements, Electrophoresis, Or Variable Reflection Or Absorption Elements (AREA)
EP06026309A 2006-12-19 2006-12-19 Sicherheitsdokument mit elektrochromem Bauteil Withdrawn EP1936603A1 (de)

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EP06026309A EP1936603A1 (de) 2006-12-19 2006-12-19 Sicherheitsdokument mit elektrochromem Bauteil

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Cited By (3)

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US20130147179A1 (en) * 2010-06-04 2013-06-13 Polyvalor, Limited Partnership Metameric security devices using an active material
WO2016203769A1 (ja) * 2015-06-15 2016-12-22 凸版印刷株式会社 透かし用紙
US20180240376A1 (en) * 2015-05-20 2018-08-23 Fondazione Istituto Italiano Di Tecnologia Packaging label and method for labelling a package

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EP0490658A1 (de) * 1990-12-11 1992-06-17 Donnelly Corporation Zu anhaltender Färbung fähige elektrochrome Vorrichtung
WO1997045767A1 (en) * 1996-05-30 1997-12-04 Midwest Research Institute Photoelectrochemical-electrochromic device
EP1134694A1 (de) * 2000-03-16 2001-09-19 Infineon Technologies AG Dokument mit integrierter elektronischer Schaltung
US6369793B1 (en) * 1998-03-30 2002-04-09 David C. Zimman Printed display and battery
US20030169574A1 (en) * 2002-03-08 2003-09-11 Fujitsu Limited IC card and method of operating the same
WO2006029857A2 (de) * 2004-09-17 2006-03-23 Ovd Kinegram Ag Sicherheitsdokument mit elektrisch gesteuertem anzeigenelement
EP1736323A1 (de) * 2005-06-22 2006-12-27 European Central Bank Sicherheitsdokument mit einem Stromverzorgungsmittel, das ein Sicherheitsmittel steuert

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US4472627A (en) * 1982-09-30 1984-09-18 The United States Of America As Represented By The Secretary Of The Treasury Authenticating and anti-counterfeiting device for currency
EP0490658A1 (de) * 1990-12-11 1992-06-17 Donnelly Corporation Zu anhaltender Färbung fähige elektrochrome Vorrichtung
WO1997045767A1 (en) * 1996-05-30 1997-12-04 Midwest Research Institute Photoelectrochemical-electrochromic device
US6369793B1 (en) * 1998-03-30 2002-04-09 David C. Zimman Printed display and battery
EP1134694A1 (de) * 2000-03-16 2001-09-19 Infineon Technologies AG Dokument mit integrierter elektronischer Schaltung
US20030169574A1 (en) * 2002-03-08 2003-09-11 Fujitsu Limited IC card and method of operating the same
WO2006029857A2 (de) * 2004-09-17 2006-03-23 Ovd Kinegram Ag Sicherheitsdokument mit elektrisch gesteuertem anzeigenelement
EP1736323A1 (de) * 2005-06-22 2006-12-27 European Central Bank Sicherheitsdokument mit einem Stromverzorgungsmittel, das ein Sicherheitsmittel steuert

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130147179A1 (en) * 2010-06-04 2013-06-13 Polyvalor, Limited Partnership Metameric security devices using an active material
US10011140B2 (en) * 2010-06-04 2018-07-03 Polyvalor, Limited Partnership Metameric security devices using an active material
US20180240376A1 (en) * 2015-05-20 2018-08-23 Fondazione Istituto Italiano Di Tecnologia Packaging label and method for labelling a package
WO2016203769A1 (ja) * 2015-06-15 2016-12-22 凸版印刷株式会社 透かし用紙
JP2017001354A (ja) * 2015-06-15 2017-01-05 凸版印刷株式会社 透かし用紙
CN107709032A (zh) * 2015-06-15 2018-02-16 凸版印刷株式会社 水印纸
US10737525B2 (en) 2015-06-15 2020-08-11 Toppan Printing Co., Ltd. Watermarked paper

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