(19)
(11)EP 3 421 253 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
31.07.2019 Bulletin 2019/31

(21)Application number: 17178488.7

(22)Date of filing:  28.06.2017
(51)International Patent Classification (IPC): 
B42D 25/36(2014.01)
B42D 25/351(2014.01)

(54)

THERMOCHROMIC WINDOW

THERMOCHROMISCHES FENSTER

FENETRE THERMOCHROMIQUE


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(43)Date of publication of application:
02.01.2019 Bulletin 2019/01

(73)Proprietor: HID Global Rastede GmbH
26180 Rastede Niedersachsen (DE)

(72)Inventor:
  • SENGE, Carsten
    26129 Oldenburg (DE)

(74)Representative: Kramer Barske Schmidtchen Patentanwälte PartG mbB 
European Patent Attorneys Landsberger Strasse 300
80687 München
80687 München (DE)


(56)References cited: : 
WO-A1-2014/029686
DE-A1-102011 108 527
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    Technical field



    [0001] The invention relates to a security feature in an identification card.

    Background of the invention



    [0002] It is known to use a thermochromic effect to make information that is embedded in the identification card appear upon thermal activation of the identification card. One such product is offered for sale under the brand name FEEL®-ID. This product departs from an identification card in which an information is embedded. This information is overprinted with a thermochromic ink which is opaque under normal use conditions. Upon application of heat to the thermochromic ink, the opacity changes, i.e., the thermochromic ink becomes transparent and the hidden information underneath is displayed.

    [0003] Nowadays, there is an increased interest for security features in identification cards, which among others allow to check the authenticity of the card and at the same time protect against unauthorized copy. One popular security feature involves using a see through window in the identification card.

    [0004] WO 2014/029686 A1, which discloses an identification card according to the preamble of claim 4, refers to a security document with a hologram in a visually changeable window as a novel security element, and also to a method for producing the same. The document of security disclosed therein comprises at least one window formed from a multilayer assembly. The multilayer assembly has at least one layer comprising at least one photopolymer and incorporating at least one hologram and at least one transparent, optically switchable layer which becomes non-transparent by means of heat or irradiation.

    [0005] DE 10 2011 108527 A1 shows a data carrier card comprising a card body including one or several foils and a security thread integrated in the card body. At least one of the foils is manufactured by coextrusion and has at least two strips lying side by side in the area dimension. At least one strip is a thread strip which differs in at least one material property from the bordering strips. At least one printed layer is applied to the thread strip as an overprint or underprint. The thread strip forms by cooperation with the at least one printed layer the security thread or a part of the security thread. Hence the invention aims to provide an identification card with a security feature that is highly secure against fraud and gives an attractive visual appearance.

    Summary of the invention



    [0006] In a first aspect, the invention provides a method according to claim 1.

    [0007] In a preferred embodiment a thermochromic layer's color is black when the level of heat is inferior or equal to the determined threshold value.

    [0008] In a further preferred embodiment, the method further comprises overprinting a pattern on at least a part of the thermochromic layer on at least one side of the transparent window with color shifting ink with non-mineral pigment, wherein the color shifting ink with non-mineral pigment is visible over the thermochromic layer when this is dark colored, i.e., when the level of heat is inferior or equal to the determined threshold value, and the color shifting ink with non-mineral pigment appears substantially invisible when the thermochromic layer is exposed to the level of heat greater than the determined threshold value.

    [0009] In a second aspect, the invention provides an identification card according to claim 4.

    [0010] In a further preferred embodiment of the identification card, a thermochromic layer's color is black when the level of heat is inferior or equal to the determined threshold value.

    [0011] In a further preferred embodiment of the identification card , the identification card further comprises on at least one side of the transparent window, on at least a part of the thermochromic layer an overprinted pattern of color shifting ink with non-mineral pigment, wherein the color shifting ink with non-mineral pigment is visible over the thermochromic layer when this is dark colored, i.e., when the level of heat is inferior or equal to the determined threshold value, and the color shifting ink with non-mineral pigment appears substantially invisible when the thermochromic layer is exposed to the level of heat greater than the determined threshold value.

    [0012] In a further preferred embodiment, the thermochromic layer comprises thermochromic ink which changes its color at about 30-35°C.

    Brief description of the drawings



    [0013] The invention will be better understood through the description of preferred embodiments, and in reference to the drawings, wherein

    Fig. 1 shows an example embodiment of an identification card according to the invention;

    Fig. 2 contains a flowchart illustrating an example embodiment of a method for manufacturing a secured window in an identification card according to the invention;

    Fig. 3 shows a further example embodiment of an identification card in a sectional view according to the invention, involving color shifting ink;

    Fig. 4 contains a further example embodiment of an identification card involving a transparent core, in a sectional view, according to the invention, and

    Fig. 5 contains a further example embodiment of an identification card involving a transparent core covered on each of its sides by an opaque layer, in a sectional view, according to the invention.


    Detailed description of preferred embodiments



    [0014] Fig. 1 shows an example embodiment of an identification card according to the invention.

    [0015] The identification card comprises a core layer 4, which may be a pre-laminated layer, and a first transparent foil 2 and a second transparent foil 5 arranged respectively on opposite sides of the core layer 4. The core layer 4 may comprise electronic components, such as for example an antenna or a transponder-no electronic components are shown in Fig. 1 for a better readability.

    [0016] The core layer 4 comprises a transparent window 3. The window may comprise an information (not shown in Fig. 1) that may be seen visually by looking through the window 3. The information may be of graphical nature and/or imprinted on the window 3. The information may also be a feature of the core layer that would be positioned in an aperture of the window 3, such as for example an electronic component, which would hence become visible when one looks through the window 3. The information may alternatively also be superposed on a side of the window, effectively coming from a carrier that is distinct from the window of the core layer 4.

    [0017] The first transparent foil 2 and the second transparent foil 5 respectively comprise a first thermochromic layer 1 and a second thermochromic layer 6. Both first and second thermochromic layers 1 and 6 may be seen as elements of delimited sizes, partly covering a surface of the first and second transparent foils respectively. Preferably each of the first and second thermochromic layers 1 and 6 have a size and shape that at least covers a side of the window 3. The first and second thermochromic layers 1 and 6 are positioned on their respective carrier foils in such a manner that they cover respective sides of the window 3 when the core layer 4 and the foils 2 and 5 are assembled to become an identification card.

    [0018] As already hinted in the context of prior art, the thermochromic layers are opaque under normal use conditions. Upon application of heat to the thermochromic layers, the opacity changes, i.e., the thermochromic layers become transparent and the information underneath, i.e., at the level of the window 3 is displayed, because there is a transparent visual path allowing to see through. Typically, the heat should exceed a determined threshold value for the desired effect of opacity change to occur.

    [0019] In a preferred embodiment a thermochromic layer's color is black when the level of heat is inferior or equal to the determined threshold value.

    [0020] In a preferred embodiment, the thermochromic ink changes its color at about 30-35°C, so it is black at normal room temperature, but can be changed with the "heat" of the human body.

    [0021] In a preferred embodiment the thermochromic layers may comprise thermochromic paint.

    [0022] In a preferred embodiment the thermochromic layer is a printed patch.

    [0023] In a further preferred example embodiment as shown in the sectional view of an identification card in Fig. 3, a pattern made with layers 7 and 8 of a color shifting ink with non-mineral pigment, respectively between the first thermochromic layer 1 and the first transparent film 2, and between the second thermochromic layer 6 and the second transparent film 5.

    [0024] In the upper part of Fig. 3, labelled A, the first and the second thermochromic layers 1 and 6 are at a temperature that lies below the determined threshold value, rendering them opaque. This is illustrated by the black texture of the thermochromic layers in Fig. 3, part A. In this situation, the color shifting ink is visible over the respective thermochromic layers, i.e., when seen respectively from above and below the identification card.

    [0025] When the temperature of the first and the second thermochromic layers 1 and 6 is above the determined threshold value, these become transparent, and the color shifting ink is then invisible. This is represented by the absence of any texture in the thermochromic layers 1 and 6 in Fig. 3, part B, which is illustrated in the below part of Fig. 3.

    [0026] The identification card according to the invention is particularly safe as the information hidden at the level of the window is covered from both sides. If only one side had been covered, it would possibly still be possible to illuminate the uncovered side of the window and see the information by an effect of the reflected light.

    [0027] The identification card according to the invention is esthetically pleasing as the see-through window 3 may instantly be produced by means of application of heat only. This allows for a large variety of types of information to be included at the level of the window 3, including 3-dimensional shapes, partly translucid objects, etc.

    [0028] In a preferred embodiment, the core layer 4 is opaque, and comprises the window 3 as an aperture therein, the first and second transparent foils 2 and 5 carry on their sides oriented to the core layer 4, respectively the first and second thermochromic layers 1 and 6, whereby at least one of the thermochromic layers is imprinted with the information, for example an artwork, on the side oriented to the window 3.

    [0029] In a further preferred embodiment, shown in the sectional view of Fig. 4, the core layer 4 is transparent and doesn't have any window that is explicitly formed therein, but rather comprises a zone 9 of the core layer 4, delimited in the figure by dotted lines, that is defined as a window 3, which is transparent just the same as the remaining core layer 4 around it. The first transparent foil 1 and the second transparent foil 5 may be covered by a opaque layer of paint 10 and 11 respectively.

    [0030] In a further preferred embodiment, the information and the thermochromic layer are deposited directly on each side of the window 3. In this case the window must be delimited on each of its sides by a solid transparent surface.

    [0031] In a further preferred embodiment represented in the sectional view of Fig. 5, the core layer 4 may for example be of a transparent material and entirely covered on each side by a layer of opaque paint 12 and 13, or an opaque foil with a partial opening, except for a part 14 and 15 on each side of the core layer 4 corresponding to the window 3. The information may then be deposited directly on at least one of the surfaces of the window 3, and both surfaces of the window 3 subsequently covered by the thermochromic layer. The finished core layer product may then be covered on each side by a transparent foil as a means of protection.

    [0032] Turning now to Fig. 2, this contains a flowchart illustrating an example embodiment of a method for manufacturing a secured window in an identification card according to the invention. The method starts of by the step of printing "hidden" information on a transparent sheet-as part of the inlet for the identification card-thereby embedding information in the transparent window of the identification card. This is followed by an assembling of the transparent inlet and a prelamination step.

    [0033] Fig. 2 then shows a reverse side print of an opaque white print which may optionally be executed on the front side and/or back side of the card, or on a separate opaque sheet with opening.

    [0034] This is followed by a reverse side print of artwork which is done on the front side of the card and on the back side of the card.

    [0035] Then is executed a reverse side print of thermochromic ink on the front side window and the back side window, effectively covering the embedded information with a thermochromic layer.

    [0036] Subsequently and optionally, there is a step of side print of color shifting ink on the front side of the card and/or the back side of the card. Eventually the printed sheets are assembled with the inlet and a final lamination step takes place.

    List of reference numerals:



    [0037] 
    1
    first thermochromic layer
    2
    first transparent foil
    3
    transparent window
    4
    card core
    5
    second transparent foil
    6
    second thermochromic layer
    7
    layer of a color shifting ink
    8
    layer of a color shifting ink
    9
    zone of core layer defining a window
    10
    opaque layer
    11
    opaque layer
    12
    opaque paint
    13
    opaque paint



    Claims

    1. A method for manufacturing a secured window in an identification card, comprising:

    - providing a transparent window (3) in the identification card;

    - embedding information in the transparent window (3),

    - covering a first side of the transparent window and the embedded information with a thermochromic layer (1), the thermochromic layer (1) becoming substantially transparent when subjected to a level of heat greater than a determined threshold value;

    - covering a second side of the transparent window (3), opposite to the first side, with a further thermochromic layer (6), such that the embedded information becomes visible through the transparent window (3) when both sides of the transparent window (3) are exposed to the level of heat greater than the determined threshold value.


     
    2. The method of claim 1, wherein a thermochromic layer's color is black when the level of heat is inferior or equal to the determined threshold value.
     
    3. The method of any one of claims 1 and 2, further comprising

    - overprinting a pattern on at least a part of the thermochromic layer (1, 6) on at least one side of the transparent window (3) with color shifting ink (7, 8) with non-mineral pigment, wherein the color shifting ink (7, 8) with non-mineral pigment is visible over the thermochromic layer (1, 6) when this is dark colored, i.e., when the level of heat is inferior or equal to the determined threshold value, and the color shifting ink (7, 8) with non-mineral pigment appears substantially invisible when the thermochromic layer (1, 6) is exposed to the level of heat greater than the determined threshold value.


     
    4. An identification card provided with a secured transparent window, comprising

    - a transparent window (3) in the identification card;

    - embedded information in the transparent window (3);

    - a first thermochromic layer (1) covering a first side of the transparent window (3), the first thermochromic layer (1) covering the embedded information and becoming substantially transparent when subjected to a level of heat greater than a determined threshold value;

    characterised in that it further comprises:

    - a second thermochromic layer (6) covering a second side of the transparent window (3), opposite to the first side, such that the embedded information becomes visible through the transparent window (3) when both sides of the transparent window (3) are exposed to the level of heat greater than the determined threshold value.


     
    5. The identification card of claim 4, wherein a thermochromic layer's color is black when the level of heat is inferior or equal to the determined threshold value.
     
    6. The identification card of any one of claims 4 and 5, wherein the identification card further comprises on at least one side of the transparent window (3), on at least a part of the thermochromic layer (1, 6) an overprinted pattern of color shifting ink (7, 8) with non-mineral pigment, wherein the color shifting ink (7, 8) with non-mineral pigment is visible over the thermochromic layer (1, 6) when this is dark colored, i.e., when the level of heat is inferior or equal to the determined threshold value, and the color shifting ink with non-mineral pigment appears substantially invisible when the thermochromic layer (1, 6) is exposed to the level of heat greater than the determined threshold value.
     
    7. The identification card of any one of claims 4 to 6, wherein the thermochromic layer (1, 6) comprises thermochromic ink which changes its color at about 30-35°C.
     


    Ansprüche

    1. Verfahren zum Herstellen eines sicheren Fensters in einem Ausweis, enthaltend:

    - Vorsehen eines transparenten Fensters (3) in dem Ausweis

    - Einbetten von Information in dem transparenten Fenster (3)

    - Abdecken einer ersten Seite des transparenten Fensters und der eingebetteten Information mit einer thermochromatischen Schicht (1), wobei die thermochromatische Schicht (1) im Wesentlichen transparent wird, wenn sie einem Wärmeniveau ausgesetzt ist, das höher ist als ein bestimmter Grenzwert

    - Abdecken einer zweiten Seite des transparenten Fensters (3), entgegengesetzt zu der ersten Seite, mit einer weiteren thermochromatischen Schicht (6), so dass die eingebettete Information durch das transparente Fenster (3) sichtbar wird, wenn beide Seiten des transparenten Fensters (3) dem Wärmeniveau ausgesetzt sind, das höher ist als der bestimmte Grenzwert.


     
    2. Verfahren nach Anspruch 1, bei dem die Farbe der thermochromatischen Schicht Schwarz ist, wenn das Wärmeniveau niedriger oder gleich dem bestimmten Grenzwert ist.
     
    3. Verfahren nach einem der Ansprüche 1 und 2, weiter enthaltend:

    - Aufdrucken eines Musters auf zumindest einen Teil der thermochromatischen Schicht (1, 6) auf zumindest einer Seite des transparenten Fensters (3) mit einer die Farbe wechselnden Tinte (7, 8) mit nicht-mineralischem Pigment, wobei die die Farbe wechselnde Tinte (7, 8) mit nicht-mineralischem Pigment über der thermochromatischen Schicht (1, 6) sichtbar ist, wenn diese dunkel gefärbt ist, d.h., wenn das Wärmeniveau niedriger oder gleich dem bestimmten Grenzwert ist, und die die Farbe wechselnde Tinte (7, 8) mit nicht-mineralischem Pigment im Wesentlichen unsichtbar erscheint, wenn die thermochromatische Schicht (1, 6) dem Wärmeniveau ausgesetzt ist, das größer als der bestimmte Grenzwert ist.


     
    4. Ausweis mit einem sicheren transparenten Fenster, enthaltend:

    - ein transparentes Fenster (3) in dem Ausweis

    - eingebettete Information in dem transparenten Fenster (3)

    - eine erste thermochromatische Schicht (1), die eine erste Seite des transparenten Fensters (3) bedeckt, wobei die erste thermochromatische Schicht (1) die eingebettete Information bedeckt und im Wesentlichen transparent wird, wenn sie einem Wärmeniveau ausgesetzt ist, das höher als ein bestimmter Grenzwert ist,

    dadurch gekennzeichnet, dass dieser weiter enthält:

    - eine zweite thermochromatische Schicht (6), die eine zweite Seite des transparenten Fensters (3) entgegengesetzt zu der ersten Seite so bedeckt, dass die eingebettete Information durch das transparente Fenster (3) sichtbar wird, wenn beide Seiten des transparenten Fensters (3) einem Wärmeniveau ausgesetzt sind, das höher als der bestimmte Grenzwert ist.


     
    5. Ausweis nach Anspruch 4, bei dem die Farbe einer thermochromatischen Schicht Schwarz ist, wenn das Wärmeniveau geringer oder gleich dem bestimmten Grenzwert ist.
     
    6. Ausweis nach einem der Ansprüche 4 und 5, bei dem der Ausweis ferner auf zumindest einer Seite des transparenten Fensters (3) auf zumindest einem Teil der thermochromatischen Schicht (1, 6) ein aufgedrucktes Muster aus einer die Farbe wechselnden Tinte (7, 8) mit nicht-mineralischem Pigment enthält, wobei die die Farbe wechselnde Tinte (7, 8) mit nicht-mineralischem Pigment über der thermochromatischen Schicht (1, 6) sichtbar ist, wenn diese eine dunkle Farbe hat, d.h., wenn das Wärmeniveau geringer oder gleich dem bestimmten Grenzwert ist, und die die Farbe wechselnde Tinte mit nicht-mineralischem Pigment im Wesentlichen unsichtbar erscheint, wenn die thermochromatische Schicht (1, 6) dem Wärmeniveau ausgesetzt ist, das größer als der bestimmte Grenzwert ist.
     
    7. Ausweis nach einem der Ansprüche 4 bis 6, bei dem die thermochromatische Schicht (1, 6) thermochromatische Tinte enthält, die ihre Farbe bei etwa 30-35°C ändert.
     


    Revendications

    1. Procédé de fabrication d'une fenêtre sécurisée dans une carte d'identification, comprenant les étapes consistant à :

    - fournir une fenêtre transparente (3) dans la carte d'identité ;

    - intégrer les informations dans la fenêtre transparente (3),

    - recouvrir un premier côté de la fenêtre transparente et les informations intégrées avec une couche thermochromique (1), la couche thermochromique (1) devenant sensiblement transparente lorsqu'elle est soumise à un niveau de chaleur supérieur à une valeur seuil déterminée ;

    - recouvrir un deuxième côté de la fenêtre transparente (3), opposé au premier côté, d'une autre couche thermochromique (6), de sorte que les informations intégrées deviennent visibles à travers la fenêtre transparente (3) lorsque les deux côtés de la fenêtre transparente (3) sont exposés à un niveau de chaleur supérieure à la valeur seuil déterminée.


     
    2. Procédé selon la revendication 1, dans lequel la couleur d'une couche thermochromique est noire lorsque le niveau de chaleur est inférieur ou égal à la valeur seuil déterminée.
     
    3. Procédé selon l'une quelconque des revendications 1 et 2, comprenant en outre une étape consistant à

    - surimprimer un motif sur au moins une partie de la couche thermochromique (1, 6) sur au moins un côté de la fenêtre transparente (3) avec une encre de changement de couleur (7, 8) avec un pigment non minéral, dans lequel l'encre de changement de couleur (7, 8) avec un pigment non minéral est visible sur la couche thermochromique (1, 6) lorsque celle-ci est colorée sombre, c'est-à-dire lorsque le niveau de chaleur est inférieur ou égal à la valeur seuil déterminée, et l'encre de changement de couleur (7, 8) à pigment non minéral apparaît sensiblement invisible lorsque la couche thermochromique (1, 6) est exposée au niveau de chaleur supérieur à la valeur seuil déterminée.


     
    4. Carte d'identification munie d'une fenêtre transparente sécurisée, comprenant

    - une fenêtre transparente (3) dans la carte d'identité ;

    - des informations intégrées dans la fenêtre transparente (3) ;

    - une première couche thermochromique (1) recouvrant un premier côté de la fenêtre transparente (3), la première couche thermochromique (1) recouvrant les informations intégrées et devenant sensiblement transparente lorsqu'elle est soumise à un niveau de chaleur supérieur à une valeur seuil déterminée ;

    caractérisé en ce qu'il comprend en outre :

    - une seconde couche thermochromique (6) recouvrant un second côté de la fenêtre transparente (3), opposé au premier côté, de sorte que les informations intégrées deviennent visibles à travers la fenêtre transparente (3) lorsque les deux côtés de la fenêtre transparente (3) sont exposés au niveau de chaleur supérieur au seuil déterminé.


     
    5. Carte d'identification selon la revendication 4, dans laquelle la couleur d'une couche thermochromique est noire lorsque le niveau de chaleur est inférieur ou égal à la valeur seuil déterminée.
     
    6. Carte d'identification selon l'une quelconque des revendications 4 et 5, dans laquelle la carte d'identification comprend en outre, sur au moins un côté de la fenêtre transparente (3), sur au moins une partie de la couche thermochromique (1, 6), un motif surimprimé d'encre de changement de couleur (7, 8) avec pigment non minéral, dans laquelle l'encre changement de couleur (7, 8) avec pigment non minéral est visible sur la couche thermochromique (1, 6) lorsque celle-ci est colorée sombre, c'est-à-dire, lorsque le niveau de chaleur est inférieur ou égal à la valeur seuil déterminée, et l'encre de changement de couleur avec pigment non minéral apparaît sensiblement invisible lorsque la couche thermochromique (1, 6) est exposée au niveau de chaleur supérieur à la valeur seuil déterminée.
     
    7. Carte d'identification selon l'une quelconque des revendications 4 à 6, dans laquelle la couche thermochromique (1, 6) comprend une encre thermochromique qui change de couleur à environ 30 à 35° C.
     




    Drawing














    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description