Abstract:
The invention concerns a large format smart card having a card body and a minicard connected thereto by at least a strap. The strap includes a first portion arranged on the minicard side and shaped to form an imposed rupture zone for detaching the minicard by pressing with the finger. The strap also has a second portion, arranged on the card body side and capable of forming a hinge.

Description:
This disclosure is based upon, and claims priority from French Patent Application No. 98/11971, filed Sep. 24, 1998, and International Application No. PCT/FR99/02071, filed Aug. 31, 1999, the contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to cards that have electronics micro-circuits and that are more generally known as “smart cards” or “chip cards”. 
     One of the problems that is frequently encountered for mass consumer products is the problem of standardization, so that products coming from different manufacturers can be used in the same equipment. 
     This applies particularly to smart cards: they are used, for example, in public telephones, in card readers associated with personal computers, and in banking applications, etc. It has thus been necessary to adopt precise construction standards that all of the manufacturers must comply with. The general public is now very well acquainted with the format that has been adopted, at least as regards the outside dimensions of the card: it is the format of conventional credit cards with magnetic stripes. The smart card is a rectangle that is about 8.5 cm long by 5.4 cm wide, and that is a little less than one millimeter thick (international Standards ISO 7810 and 7816 today). 
     As a result, naturally, the machines for manufacturing smart cards are built as a function of those standards, so as to be capable of producing cards that comply with the standards. 
     But in certain applications, it has become apparent that that format is not ideal. This applies in particular for miniaturized applications. For example, when a smart card is to be used in a handheld housing of very small size, the current format, despite its small size, is not necessarily acceptable. By way of example, mention might be made of the mobile radiotelephone or “cellphone” whose handheld housing needs to use smart cards of format much smaller than the current format and complying with the GSM 11-11 Standard. 
     An object of the invention is to provide an inexpensive technical solution for making smart cards of format smaller than the generally-used format. 
     Methods have already been proposed in the prior art for making smart cards of small format. A method, described in particular in Patent EP-0 521 778, consists in performing all of the steps of manufacturing a smart card of standard format, and in performing an additional step of partially pre-cutting the standard-format card so that a small-format card can be detached from it merely by pressing with the fingers. The partial pre-cutting is performed around a micromodule contained in the card. The pre-cut is constituted by a slot extending around the outline of the small-format card, the slot being interrupted locally to leave webs between the small-format card and the standard-format card. In particular, those webs are of reduced thickness in the vicinity of the small-format card so as to enable it to be separated from the remainder of the body of the standard-format card merely by pushing it out with the fingers. 
     A major drawback of that type of method lies in the fact that the small-format card can, under certain rare conditions, not be detached very cleanly. The shear forces can be insufficiently concentrated on the location at which the detaching should take place, so that the small-format card can have uneven edges. In addition, during bending testing over the width of the standard-format card, the webs can be twisted and can be subjected to stresses. Exceptionally, such stresses can damage the micromodule contained in the card or can break one of the webs or “straps” unintentionally. In which case, the large-format card might not comply with Standard ISO 7816 as regards its bending and twisting strength. 
     SUMMARY OF THE INVENTION 
     The invention makes it possible to solve the above-mentioned problems by proposing an improved card. To this end, it provides a large-format smart card comprising a card body and a mini-card which is connected thereto by at least one strap, said strap including at least one portion disposed in the vicinity of the mini-card and shaped to constitute a place at which breaking is forced to occur or a “score line” in order to enable the mini-card to be separated by pushing it out with a finger, said smart card being characterized in that said strap also includes a second portion disposed in the vicinity of the card body and suitable for forming a hinge. 
     According to another characteristic of the invention, the hinge is constituted by a thinned neck formed by thinning the thickness of the strap. 
     According to yet another characteristic of the invention, the thinned neck is in the form of a trough having a rounded profile. 
     According to yet another characteristic of the invention, the score line is formed by two scores respectively on the front and on the back of the card. 
     According to yet another characteristic of the invention, the strap(s) is/are provided with connection fillets for connecting respectively to the card and to the mini-card. 
     According to another characteristic of the invention, the length of the strap on the side closer to the mini-card is shorter than the length of the strap on the side closer to the card body. 
     According to yet another characteristic, the smart card further comprises a long strap along a short side of the mini-card, which long strap includes a score line formed by two scores that extend over its entire length and on respective ones of both the front and the back of the card. 
     By subdividing the strap into two separate portions respectively comprising a thinned neck and a score line, the mechanical stresses are also separated. By means of the invention, the mini-card is easier to detach, and can be detached cleanly both on the front and on the back of the card. In addition, the mini-card offers good resistance to deformation due to bending testing of the card. 
     Another object of the invention is to provide a method of making a small-format smart card, comprising the entire method of manufacturing a standard-format smart card, and an additional step of forming a partial cut-out to the dimensions of the mini-card, said partial cut-out being constituted by a slot interrupted locally by at least one strap between the small-format card and the standard-format card, characterized in that the strap(s) is/are made so that it/each of them includes a first portion disposed in the vicinity of the mini-card and shaped to constitute a score line, and a second portion disposed in the vicinity of the standard-format card and constituted by a thinned neck formed by thinning the thickness of the strap, said first and second portions being implemented over the entire length of the strap and over both the front and the back of the card. 
     The partial cut-out makes it possible in particular to detach a card of predetermined small size from the card of standardized size. 
     The small card is detached only after the end of all of the manufacturing, testing, and customization printing operations, so that any standard manufacturing and testing equipment can be used without having to satisfy any constraint due to the small size desired for the final card. 
     Therefore, the manufacturing cost is low because it is not necessary to invest in costly additional manufacturing equipment merely to overcome the size problems. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and advantages of the invention will appear on reading the following description given by way of non-limiting example and with reference to the accompanying figures, in which: 
     FIG. 1 shows the principle of the invention for making a small-format card; 
     FIG. 2 is a view on a larger scale showing an example of a pre-cut using an interrupted slot allowing straps of material to remain; 
     FIG. 3 is a view in section on B—B of FIG.  2  through the thickness of a strap; 
     FIG. 4 is a plan view on a larger scale of the strap of FIG. 3; and 
     FIG. 5 is a view in section on D—D of FIG.  2  through the thickness of a long strap which is situated along a short edge of the small-format card. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows how the invention is implemented. On the basis of a flat rectangular card  20  of standard format, of length 8.5 cm, of width 5.4 cm, and of thickness less than one millimeter, the entire manufacturing process is performed, including testing the micromodule  22  (once said micromodule has been put in place in the top left corner of the card, with flush contacts), and testing the customization of the surfaces of the card with printed graphics. 
     But the final card may be much smaller, and its outline is shown FIG.  2 . Said outline is defined by a cut  32  and by places at which breaking is forced to occur or “score lines” disposed around the micromodule  22 . The card is to be detached along said outline. 
     A variety of methods may be used, and the card may be detached at various stages of its manufacture. For example, it may be detached, i.e. cut out, in one go at the end of manufacture. 
     In the invention, it is preferred to cut the card out partially rather than fully, and to do so at an intermediate stage. It is only at the stage of sending the card to the user, or even once the user is in possession of the card and is about to insert it into a reader built to the small-format standard, that the small-format card  30  is detached from the standard-format card  20  merely by pressing on the small-format card, e.g. with a finger. 
     When the user needs to use a large-format card, the mini-card  30  is not detached. 
     FIG. 2 shows a partial cut-out consisting of a slot  32  extending through the entire thickness of the card. This slot  32  defines and extends around the outline of the mini-card  30  except at certain locations where it is interrupted and allows straps  34  and  40  to remain that connect the small-format card  30  to the remainder of the standard-format card  20 . 
     FIG. 3 shows a view in section on B—B through a strap  34  shown in FIG.  2 . Said strap  34  is made up of two portions  35  and  36  in which it has a reduced thickness. 
     A first portion  36  situated closer to the small-format card  30  is shaped to constitute a score line. This score line is constituted in the example by scores  38 A,  38 B of conical shape formed respectively on the front face and on the back face of the card, and over the entire length l 2  of the strap  34 , as shown in FIGS. 2 and 4. These scores are, for example, formed to a depth of 150 μm on the front of the card (reference  38 A), and to a depth of 120 μm on the back of the card (reference  38 B). 
     By forming the scores on both sides of the card, it is possible to facilitate pushing-out by hand (merely by pressing with the fingers), and to perform such pushing-out cleanly both on the back of the card and on the front of the card. Thus, once it has been detached, the mini-card  30  has clean-cut and even edges. These scores constitute a preferred example of a score line. Other variants may be suitable, such as weakening, removal of material, perforation, etc. 
     In a second portion  35 , situated closer to the standard-format card  20 , the thickness is thinned on both sides, front  37 A and back  37 B. This thinning is, in particular, performed by driving a suitable tool into the portion  35  to a sufficient depth, e.g. 250 μm on each face of the card. The resulting thinned neck further extends over the entire length l 1  of the strap as shown in FIG.  2  and on the enlarged plan view of FIG.  4 . 
     In addition, this thinned neck  37 A,  37 B in the portion  35  of the strap  34  is preferably in the form of a trough having a rounded profile. This rounded shape prevents cracks from being created and from propagating during bending testing of the card. Corners that are too sharp, such as in a trapezoidal shape for example, are unsuitable because they do not prevent such cracks from propagating. 
     The thinned neck  37 A,  37 B of the strap  34  constitutes a hinge. A function of such a hinge is to provide mechanical decoupling between the card body and the first portion  36  that is shaped to constitute a place at which breaking is forced to occur or a “score line”. In this way, it is possible to avoid accidental breakage of the straps  34  and unintentional separation of the mini-card  30 . 
     A further function of the hinge is to act, while pressure is being applied intentionally, e.g. with a finger, on the mini-card  30 , to displace and to concentrate the pressure stresses towards the score line (in the first portion  36 ), thereby guaranteeing that breakage occurs at this location rather than at some other location on the strap. 
     The hinge may be obtained directly by injection molding when the card and the slot making it possible to define the outline of the small-format card are obtained by injection molding. In which case, the shape of the hinge may be equivalent to a rounded thinned neck as in FIG. 3, or, for example, may constitute a flexible blade acting as a pivot. 
     In a variant, it is possible to make the hinge of a material that is more flexible than the remainder of the card, using a known two-component injection molding technique. A distinct flexible material that is adhesion compatible with the material of the card is injected into the mold at the strap. 
     The hinge may also be discontinuous and in two portions fitting into each other, the mini-card and the card body being manufactured independently, each with a respective hinge portion designed to interfit with the complementary portion. 
     While the thinning  37 A,  37 B of the second portion  35  and of the score line  38 A,  38 B in the first portion  36  is being performed, material is driven out to the sides as a result of the tool used penetrating into the thickness of the card. The driving-out of the material is controlled to be as plane as possible in order to avoid too many rejects when customizing the cards by heat transfer. 
     The slot  32  then has two connection fillets  37 C,  38 C which appear at either end of the strap  34  as shown in FIG.  2  and in the enlarged plan view of FIG.  4 . Thus, in the planes of the surfaces of the card situated respectively above and below the portion  35  dedicated to the thinned neck, the slot  32  has a first connection fillet  37 C for connecting to the standard format card  20 ; and in the planes of the surfaces of the card situated respectively above and below the portion  36  dedicated to the score line, the slot  32  has a second connection fillet  38 C for connecting to the mini-card  30 . The radius of curvature of the connection fillet  38 C for connection to the mini-card is smaller than the radius of curvature of the connection fillet  37 C for connecting to the card body  20 . In addition, the strap  34  has a length l 2  in the vicinity of the small-format card  30  that is shorter than the length l 1  in the vicinity of the standard-format card  20 . 
     The forces with which pressure is applied to the mini-card are displaced by the hinge (second portion  35 ) towards the zone  33  situated between the two portions  35 ,  36  of the strap  34 , and they are concentrated onto the score line (first portion  36 ), so that it is possible to guarantee that the mini-card is snapped off cleanly. The mini-card  30  obtained in this way thus has clean-cut and even edges. 
     The smart card of the invention may also include other types of straps. For example, it may have a long strap  40  that extends along a short side of the mini-card  30 , as shown in the diagram of FIG.  2 . FIG. 5 shows a section view of this long strap referenced  40 , whose length l 3  is longer than the lengths of the above-described straps. This strap  40  is provided with only one score line formed by two scores  41 A,  41 B which extend over its entire length. These two scores  41 A,  41 B are formed one respective ones of both the front and the back of the card. 
     The slot  32  is provided with two small fillets  42  at the two ends of the strap  40 . These set-back fillets make it possible to ensure that the stresses are properly steered towards the scores  41 ,  41 B while the mini-card  30  is being detached, e.g. by being pushed out with a finger.