Patent Abstract:
The invention relates to a card ( 38 ) including a digital display ( 10 ) arranged in a node ( 4 ) defining the central portion of the card. It further comprises a plastic layer ( 40 ) the major portion ( 42 ) of which is opaque, and a transparent display portion ( 44 ). A pattern ( 14 ) is printed on the upper face of the plastic layer ( 40 ), in particular by an offset printing technique. The plastic layer ( 40 ) is covered with a transparent film ( 12 ) attached thereto by a thin glue layer ( 34 ) defining an adhesion interface. The electronic display ( 10 ) is fully integrated in the card ( 38 ) and the printed pattern ( 14 ) exhibits a good contrast on the opaque portion of said plastic layer. Furthermore, a good adhesion is obtained between all the layers of the card.

Full Description:
FIELD OF THE INVENTION  
       [0001]    The present invention concerns a card incorporating an electronic display. This electronic display is generally associated with an electronic data processing circuit and, in some variants, with a switch or sensor enabling a user to activate a certain function. The electronic display can display variable codes and other data for increasing the security of bankcards or secure access cards, for example. Integrating an electronic display in a card causes a particular manufacturing constraint, given that the card has to be transparent above the display. The electronic display module is located inside the card according to the invention. Thus, the display module is covered by at least one additional outer protective layer. 
       BACKGROUND OF THE INVENTION 
       [0002]    According to an advantageous method of manufacturing cards incorporating various electronic elements, the electronic elements are coated or embedded in a resin that forms a core or intermediate layer of the card. EP Patent No. 0 570 784 generally discloses a manufacturing method of this type. In order to obtain a core that has flat, uniform surfaces, it is preferable to coat all of the electronic elements incorporated in the card and thus to cover the electronic display with the resin coating. In this latter implementation made, the resin must be transparent at least in the display area. The transparency of the resin causes a problem as regards obtaining high quality printing, in particular on the top surface of the card where the display appears. Consequently, it raises a dual problem. Generally speaking, printing patterns on a transparent layer causes a decrease both in colour intensity and contrast, so that the colours have a translucent appearance. Secondly, the presence of various electronic elements in the transparent core causes variations in light reflected by the core, which results in darker areas on the surfaces of the core. The support on which a pattern is printed is thus not optically uniform, which generally leads to variations in contrast and variations in colour intensity on the top surface side of the finished card. 
         [0003]    In order to overcome the aforementioned problem, in manufactured cards of the prior art, a light-coloured, preferably white, ink or varnish is deposited underneath the printed patterns relative to the core of the card, via a silkscreen printing technique, so that the thin layer of ink or varnish has a certain thickness. Two variants of cards made in accordance with this technique are shown in  FIGS. 1 and 2 . 
         [0004]    Card  2  of  FIG. 1  is formed of a core  4  incorporating an electronic unit  8  and an electronic display  10 . These electronic elements  8  and  10  are embedded in a transparent resin  6  that forms core  4 , which is made in a first step of a manufacturing method for such cards. Core  4  is formed by a technique known to those skilled in the art, in particular in a press or by injecting the resin into a mould. Next, a transparent film  12  is arranged on the top surface side of the core, on the inner surface of which a pattern  14  is printed. To obtain high quality printing, i.e. high definition, printed patterns  14  are preferably obtained by an offset printing technique. Then, according to this prior art method, a layer of ink or varnish  16  is printed on pattern  14 . This layer  16  is preferably white and it extends over the entire bottom surface of transparent film  12  except for the display area located above electronic display  10 . Layer  16  thus defines a window through which electronic display  10  is visible. 
         [0005]    Likewise, a transparent film  18  is arranged on the bottom surface side of the card  2 , on the top surface of which a pattern  20  is printed. This pattern  20  is covered by a layer of ink or varnish  22 . Layer  22  is also preferably deposited by silkscreen printing. However, it should be noted that bottom layers  16  and  22  might be deposited by various techniques. 
         [0006]    Card  22  according to the variant shown in  FIG. 2  includes a core  24  formed of a resin or any material  26 . Core  24  differs from core  4  of  FIG. 1  in that the electronic display  10  at the top surface thereof is flush with the top surface of core  24 . Unlike the preceding variant, material  26  does not have to be transparent here. Material  26  may be added in liquid form in a press or injection moulding installation, as for core  4  of  FIG. 1 . In another method of manufacturing core  24 , electronic display  10  can be inserted in a shell with a preformed housing or in the aperture of a layer forming core  24 , which may be formed of one or several layers assembled by lamination or by press bonding. In order to have a flat, uniform support for printing pattern  14 , a transparent film  30  is arranged on the top surface of core  24 . A layer of ink or varnish  16  is deposited on the top surface of film  30 , leaving a window for electronic display  10 . Pattern  14  is printed on this bottom layer  16  by an offset technique. A transparent external film  12  is then assembled to printed film  30 . A fine layer of adhesive or resin is provided between printed film  30  and external film  12  to increase adherence between these two transparent films. On the bottom surface side of card  22 , an opaque layer  32  is arranged against the core, on the bottom surface of which a pattern  20  is printed. This pattern  20  is then covered by a transparent external film  18  by means of a thin layer of adhesive or resin  36 . 
         [0007]    Besides problems linked to the thickness of card  22 , when developing the present invention it was observed that embodiments of cards  2  and  22  did not efficiently resolve the previously identified problem, i.e. the problem of a decrease in contrast and low colour intensity due to the presence of a transparent layer or film behind the printed patterns  14 . Two major problems appear with the embodiments described with reference to  FIGS. 1 and 2 . 
         [0008]    First of all, the deposition of layer  16  by a printing technique does not provide a perfectly opaque background. Various experiments have demonstrated that it is necessary to deposit several layers particularly by silkscreen printing in order to obtain an opaque background providing a satisfactory visual appearance for high quality cards. Moreover, the inks or varnish that can produce this opaque background  16  are the type that have two components. Such inks or varnish have a relatively long drying time, which raises several manufacturing problems. Thus, the time necessary for printing or depositing several layers of varnish or ink for the opaque background is considerable. This raises a storage problem during the drying periods for each print or ink or varnish deposition. This results in a relatively expensive manufacturing method requiring a large storage capacity. This storage is not easy either since the printed films must not be touched during the drying periods. 
         [0009]    The second major problem is the problem of adherence of the transparent external layer  12  in finished cards  2  and  22 . The patterns  14  made by an offset printing technique adhere relatively poorly to the transparent plastic film  12 . To increase the adherence of this external layer, printed pattern  14  is generally either covered with a thin layer of adhesive or resin that adheres well to the transparent plastic film used. If the two bottom layers  32  and  18  of card  22  are laminated to each other with a printed pattern  20  and fine layer of adhesive  36  between them, the adherence between layers  32  and  18  is sufficient. It was observed that this is due to the fact that adhesive  34  slightly penetrates the printed pattern and creates a multitude of anchorage points with the layer or film on which pattern  20  is printed. In other words, printed pattern  20  is sufficiently permeable to the adhesive for the latter for form a real adherence interface between the two plastic films or layers. The same effect is observed in the case of a similar card to that of  FIG. 1  where only printed patterns  14  and  20  are provided. By selecting a resin  6  that adheres well to transparent layers  12  and  18 , these layers have sufficient adherence to core  4  because resin  6  penetrates slightly printed patterns  14  and  20  during the card lamination assembly operation. Thus, it has been observed that the presence of the bottom layer forms a barrier to the adhesive or to the resin such that they can no longer ensure the proper adherence of layer  12  in cards  2  and  22 , and respectively of layer  18  in card  2 . 
       SUMMARY OF THE INVENTION 
       [0010]    After highlighting the various aforementioned problems in the envisaged prior art solutions, shown in  FIGS. 1 and 2 , it is an object of the present invention to propose a solution for overcoming the aforementioned problems and to provide a card with an integrated electronic display therein, yet which has a very high quality printed pattern on the top surface thereof. 
         [0011]    The present invention therefore concerns a card comprising an electronic display, arranged in a core of said card, and above said core a plastic layer, the greater part of which is formed of an opaque material and of a transparent material in a display part located above said electronic display. This transparent material defines a window for reading the electronic display. 
         [0012]    In a main variant, the plastic layer forms a printing support or substrate for at least one printed pattern on the opaque part of the plastic layer. Preferably, the opaque material is white. 
         [0013]    In a preferred variant, the plastic layer is formed of a sheet made of said opaque material, in which an aperture has been made in said display area. A transparent plate is arranged in said aperture. The thickness of the plate is preferably approximately equal to that of the opaque sheet. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The present invention will be described in more detail in the following description, made with reference to the annexed drawings, given by way of non-limiting example, in which: 
           [0015]      FIGS. 1 and 2  respectively show two transverse cross-sections of cards made in accordance with a method prior to the present invention; 
           [0016]      FIG. 3  is a transverse cross-section of a card according to the present invention; 
           [0017]      FIG. 4  shows an alternative embodiment of the card according to the invention; 
           [0018]      FIG. 5  shows a pierced opaque sheet involved in forming the card of  FIGS. 3 and 4 ; 
           [0019]      FIG. 6  shows schematically a first variant of a printed opaque sheet that has windows filled with a transparent material; and 
           [0020]      FIG. 7  shows how one part of the card shown in  FIG. 3  is formed in accordance with a specific manufacturing method. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]      FIG. 3  shows an embodiment of a card according to the invention. This card  38  has a core  4 , similar to the core of card  2  of  FIG. 1 , in which an electronic unit  8  and electronic display  10  are embedded. Core  4  is formed by a transparent resin  6 , which also covers electronic display  10 . The electronic elements are thus coated or embedded in resin  6 , which defines a compact core with two approximately flat surfaces. It will be noted that, in other variants of the cores, the electronic elements are merely covered by the resin without being entirely coated by said resin. 
         [0022]    A layer  40 , formed partly by an opaque material  42  and by a transparent material  44 , is arranged on core  4 , above electronic display  10  such that the display is visible from outside card  38 . The greater part  42  of layer  40  is formed of opaque material, which is preferably white. Only one aperture  46 , defined by opaque part  42  in the display area above electronic display  10 , is filled by a transparent part  44 . This aperture  46  defines a window whose dimensions are such that only the part used for the display of characters, numbers or other patterns of display unit  10  is visible. The thickness of transparent part  44  is approximately equal to that of opaque part  42 . Thus, outside window  46 , layer  40  defines a perfectly opaque light-coloured background for printing patterns  14  on the top surface of layer  40 . Pattern  14  is preferably printed by an offset technique. A transparent external layer  12  is arranged on printed layer  40 , using a thin layer of adhesive  34  ensuring that external layer  12  adheres properly to intermediate layer  40 . As previously explained, given that it is only necessary to print a pattern, in particular in an offset printing installation, the thin layer of adhesive really defines an adherence interface between layers  40  and  12 . The problems mentioned in relation to cards  2  and  22  of the prior art are thus solved by card  38  according to the invention. 
         [0023]    In order to obtain a symmetrical card that also has a high quality print on the bottom surface of the card, an opaque layer  32  is added, on the bottom surface of which a pattern  20  is printed. Next, a transparent external layer  18 , coated with a thin layer of adhesive  36  is added against printed sheet  32 . The whole assembly is laminated in a press or using laminating rollers to ensure its assembly. Cards are thus obtained that have an integrated electronic display inside the card, visible through transparent layers or films, while outside the display area there is a print on a relatively thick opaque layer that allows very good contrast and good colour intensity. It will be noted that one could envisage having an electronic display on the bottom surface of the card or on the two sides of the card. 
         [0024]    Card  48  shown in cross-section in  FIG. 4  is a variant made from a similar core  24  to that of card  22  shown in  FIG. 2 . On the top surface of core  24  there is a layer  40  of plastic material, the greater part  42  of which is formed of an opaque material. In the display area located above display unit  10 , layer  40  has a part  44  formed of a transparent material. A printed pattern  14  is provided on opaque part  42 . The printed layer  40  is covered with a transparent film  12 . In this variant, there is no thin layer of adhesive between layer  40  and film  12 . However, in another variant, a film acting as adherence interface may be arranged between layer  40  and external film  12 . It will be noted that it is also possible to provide a thin layer of resin or adhesive between plastic layer  40  and core  24  to ensure that plastic part  40  adheres well to electronic display  10 . This fine layer of adhesive is advantageously applied on the bottom surface of layer  40  before assembly to core  24 . The thin adhesive layer may alternatively be deposited beforehand on the top surface of core  24  or be added in the form of a thin sheet arranged between layer  40  and core  24 . These different alternatives and variants also apply to the arrangement of a fine layer of adhesive or resin between layer  40  and external layer  12 . 
         [0025]    Pattern  14  can be printed, in a variant, on the bottom surface of transparent film  12 . This transparent film is then positioned such that printed pattern  14  is opposite opaque part  42 . 
         [0026]    On the side of the bottom surface of core  24  an opaque layer  32  and a transparent external film  18  are arranged, with a printed pattern  20  between them. 
         [0027]    It will be noted that a transparent lacquer may replace transparent external films  12  and  18 , for example, or any other transparent material that can protect printed patterns  14  and  20 . 
         [0028]      FIG. 5  shows a pierced plastic sheet  50  used to form layer  40  for a plurality of batch-manufactured cards. The contour  58  of the cards, obtained after cutting the finished cards from the batch, is represented by a dotted line. The sheet  50  has an aperture  46  for each card. The largest part  42  is formed by the opaque material of sheet  50 , particularly PVC. Patterns  14  can be printed on this sheet either before making apertures  46 , or after this operation. Printing beforehand provides a printed pattern that perfectly surrounds the aperture provided for each card. 
         [0029]      FIG. 6  shows an intermediate product  52  involved in a first implementation of a card manufacturing method according to the invention. 
         [0030]    Intermediate product  52  is formed of sheet  50 , shown in  FIG. 5 , which defines a plurality of opaque parts  42  for a corresponding plurality of cards. In apertures  46  of sheet  50  there are transparent parts  44 , which have approximately the same thickness as parts  42 , so as to form an intermediate product  52  that defines a flat structure. A plurality of patterns  14  is printed on the top surface of sheet  50 . Transparent parts  44  are preferably formed by plates cut from a transparent sheet and inserted into apertures  46 . Plates  44  can be obtained in other ways known to those skilled in the art. 
         [0031]    Those skilled in the art can use various assembly techniques to ensure that plates  44  remain in place until the step for laminating them to the cores of the manufactured cards. For example, a few weld spots can be made using a simple heated tool tip, applied to the edge of apertures  46 . The plastic material melts locally, which creates weld spots and thus assembles plates  44  to sheet  50 . These weld spots are preferably made on the bottom surface of sheet  50 , i.e. on the side opposite the printed surface. However, it is also possible to make these weld spots carefully on the side of the printed surface, in particular when printing is carried out subsequently. It is also possible to secure plates  44  using an adhesive. This bonding step to keep transparent plates  44  in place may be combined with the deposition of a thin layer of adhesive on the bottom surface and/or the top surface of intermediate product  52 . Transparent plates  44  may also be assembled to pierced plate  50  in a laminating step. It will be noted that this lamination may also be provided in addition to the aforementioned spot assembly. Providing heat can thus at least partially weld the lateral faces of the plates to the wall of the corresponding apertures  46  and provide a flat, uniform layer. The layer may then be used in a method of forming cards at a relatively low temperature. 
         [0032]    Intermediate product  52  is particularly advantageous for a method where patterns  14  are printed after the opaque sheet has been assembled to the transparent plates, as the printing can then also partially cover the transparent plates. 
         [0033]    The transparent parts  44  may, in another way of making cards according to the invention, be obtained by injecting a transparent material through windows  46 . 
         [0034]      FIG. 7  shows a cross-section of another intermediate product  54  obtained within a second implementation of a card manufacturing method according to the invention. To obtain intermediate product  54 , opaque sheet  50  is first printed to obtain a plurality of patterns  14 . Then, a transparent film  12  covered with a layer of adhesive  34  is placed against sheet  50  on the side of printed patterns  14 . Printed sheet  50  is then assembled to transparent film  12  and housings are obtained formed by apertures  46  that have adhesive layer  34  at the bottom thereof. Transparent plates  44  are then inserted into apertures  46  and secured to film  12  via the locally heated adhesive layer, for example. An intermediate product  54  is thus obtained which can then be assembled to a core  4  or  24  to provide cards according to the present invention. It will be noted that this intermediate product can also be obtained without the adhesive layer. In this latter case, the temporary assembly is achieved via a weld spot on one side or the other, on the edge of the apertures or at the centre, by welding the plates to transparent film  12 . Preferably, the assembly thereby obtained is then laminated to obtain a properly flat, multi-layered structure, without slots and without any marks that could result from the temporary assembly of the transparent plates. 
         [0035]    In a method where the core is not made in a prior step, but is formed simultaneously while the whole card is being formed, intermediate product  54  is then used as a top, multi-layered structure, arranged in the laminating installation (flat press or rollers) on a resin in a viscous liquid state used to form a central core incorporating the electronic elements. A bottom sheet or multi-layered structure is generally arranged underneath the resin that is added in the laminating installation. Pre-assembled layers  18  and  32 , as shown in  FIG. 3  or  4 , may form this bottom multi-layered structure. The top and bottom multi-layered structures are generally laminated at a relatively high temperature, but the entire card is finally made at a low temperature or ambient temperature, to prevent damaging the electronic elements. 
         [0036]    It will be noted finally that transparent part  44  of plastic layer  40  may have various optical functions, particularly polarising or filtering functions, and have undergone various treatments, particularly an anti-reflective treatment. In an advantageous variant, this transparent part defines a Fresnel lens, which gives a magnifying effect. These functions or optical treatments are used first and foremost for increasing the reading comfort of the electronic display. However, they may also be used to give a certain visual or aesthetic appearance.

Technology Classification (CPC): 6