Abstract:
A connector is provided for memory card including an insertion module of an overall right-angle parallelepipedal shape. The insertion module includes an insertion slot for inserting a memory card. The connector furthermore includes several static electricity discharge zones coming into contact with a portion of a surface of a memory card upon the insertion of the memory card into the memory card connector. Each of the static electricity discharge zones is made at least in part of a conducting plastic material having a different surface resistance value, so that the discharge of the card is effected progressively in several phases.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This Application is a Section 371 National Stage Application of International 
         [0002]    Application No. PCT/EP2013/062791, filed Jun. 19, 2013, the content of which is incorporated herein by reference in its entirety, and published as WO 2013/190006 on Dec. 27, 2013, not in English. 
     
    
     FIELD OF THE INVENTION 
       [0003]    The invention relates to a memory card connector also called an MC connector. A memory card connector is a device enabling the insertion of a memory card. A memory card connector is generally an element comprising a memory card reader terminal. A memory card reader terminal can be, for example, a payment terminal. It can also be a personal digital assistant or again a communications terminal such as a cell phone or a Smartphone. 
       PRIOR ART 
       [0004]    There are known memory card connectors for receiving a memory card. The card for example may be, for example, a smartcard which can be a payment card. Payment cards are cards that incorporate means for identifying and authenticating a user in order to enable the performance of one or more actions such as for example a payment, a cash withdrawal, etc. 
         [0005]    A payment card often incorporates several means to enable this identification and this authentication of the user. Thus, a payment card may include a magnetic stripe and a chip. Recently, novel means of communication and/or payment have been integrated into the cards: contactless antennas, more powerful chips capable of carrying out special processing operations, etc. 
         [0006]    These novel means of communication enable novel types of use: these are for example contactless payment, reinforced authentication processing, etc. At the same time, these novel cards have new drawbacks: these cards, known as new generation cards, tend to get electrically charged to a far greater extent than do the earlier cards. Now, electrically charged cards present at least one problem: the electrical charge that builds up in the card must be discharged at some time or other. In one frequent scenario, the card gets discharged when it is being inserted into the terminal. The discharge into the terminal causes two possible results: either the card gets discharged in the terminal or the charge is conducted to the chip integrated into the card. In the former case, the terminal can be seriously damaged. In the latter case, it is the card that can be damaged. In any case, the discharge takes place from the highest potential towards the lowest potential, generally the ground, and with intensities that are generally high. If the part through which the current passes (the chip of the card, the terminal) is sensitive to these intensities, then the terminal and/or the card can be damaged. 
         [0007]    Solutions have been proposed to overcome this problem. They are of several types: integrated solutions and corrective solutions. They rely on the same approach: discharging the electrical charge when the card is inserted into the memory card connector. There also exist corrective type actions using electronic components (or the terminal or the smartcard) that are more resistant to strong currents. 
         [0008]    One classic prior art solution is described with reference to  FIGS. 1A ,  1 B,  1 C,  1 D and  1 E. These figures are isometric representations of an existing memory card connector comprising an integrated discharging solution. A memory connector  10  comprises a casing  11  and an insertion slot  12  for receiving the memory card. In addition to this casing  11 , the memory card connector comprises a metal part  13  comprising pins  14 . These pins  14  are inserted into vacant spaces of the casing  11 . These metal pins come into contact with the card when it is inserted into the memory card connector. For the discharge to be complete, the pins come into contact with the card in several places: at the chip, the edge of the card and on the face of the card not having the chip. Thus, when it is inserted, the card is at least partly discharged. Indeed, the metal part  13  is connected to the ground of the terminal and the electrical charge of the card is discharged before the chip comes into contact with the pins of the memory card connector. 
         [0009]    Corrective solutions work according to the same principle: one or more metal parts, connected to ground, are added to an existing memory card connector to enable the discharging of the charge. This operation is also complex since it requires the creation of several metal elements on the basis of an existing memory card connector. Now, the creation of such mechanical elements is complex and costly. 
         [0010]    However, although they theoretically resolve the problem of removing charge, these prior-art solutions raise yet other problems. Firstly, in the case of the integrated solution, the designing of the memory card connector is complex. It is indeed necessary to design a first part, the casing, for example out of injected plastic, and then adjoin a metal part to the rim of the casing. This metal part, therefore, needs to have been shaped beforehand with numerous folds so that the pins can take position in the vacant spaces of the casing. This mounting operation is costly. 
         [0011]    Furthermore, another problem common to both prior-art solutions is linked to the fact that the metal pins could damage the card when it is withdrawn. Indeed, the metal pins are abrasive parts that rub the card with varying degrees of intensity. Now, by being continually rubbed, a card can be damaged. 
         [0012]    In short, in the prior-art solutions, the contact is made with relatively low resistance and the addition of a resistor in a series connection takes up a great deal of space. This causes the current of the discharge to remain high and can therefore create damage to sensitive components. 
         [0013]    In addition, the contact with the memory card is done on at specific, separate instances, on zones defined by the position of the pins. Although these zones are numerous, this does not make it possible to cover each and every smartcard configuration. 
         [0014]    Finally, the basic solution of adding a strip (the corrective solution) requires the addition of an additional part, and this generates costs. 
         [0015]    Thus, the existing solutions are not satisfactory and novel solutions without the drawbacks of the prior-art solutions need to be proposed. 
       SUMMARY OF THE INVENTION 
       [0016]    The invention does not have these drawbacks of the prior art. Indeed, the invention relates to a memory card connector comprising an insertion module or insert with a generally rectangular parallelepiped shape, said insertion module comprising a memory card insertion slot. 
         [0017]    According to the invention, such a connector furthermore comprises at least one zone for discharging static electricity coming into contact with a portion of a surface of a memory card during the insertion of said memory card into said memory card connector, said zone for discharging static electricity being constituted at least partly by a conductive plastic material having a predetermined value of surface resistance. 
         [0018]    Thus, the invention makes it possible to avoid the addition of metal discharge zones which have an abrasive effect on the cards that are inserted into the memory connector. 
         [0019]    According to one particular characteristic of the invention, said predetermined value of surface resistance ranges from 10 7  Ω/square to 10 12  Ω/square. 
         [0020]    According to one particular characteristic of the invention, said predetermined value of surface resistance ranges from 10 5  Ω/square to 10 8  Ωsquare. 
         [0021]    According to one particular characteristic of the invention, said predetermined value of surface resistance is of the order of 10 7  Ω/square. 
         [0022]    According to one particular characteristic of the invention, said predetermined value of surface resistance is of the order of 10 8  Ω/square. 
         [0023]    According to one particular embodiment of the invention, said electrostatic discharge zone is formed by the totality of said memory card connector. 
         [0024]    Thus, the invention avoids the adjoining of a complementary device. The memory card connector carries out the discharging of the card by itself. According to one particular embodiment of the invention, said electrostatic discharge zone is a conductive plastic part placed at said insertion slot, said conductive plastic connector comprising a linking rod connecting said conductive plastic part to at least one ground connection of said connector. 
         [0025]    Thus, the invention enables the addition of a discharge zone that is not complex to implement or to manufacture. 
     
    
     
       DRAWINGS 
         [0026]    Other features and advantages of the invention shall appear more clearly from the reading of the following description of a preferred embodiment, given by way of a simple illustratory and non-exhaustive example and from the appended drawings, of which: 
           [0027]      FIGS. 1A ,  1 B,  1 C,  1 D and  1 E, already commented upon, illustrate a connector and a discharge device according to the prior art; 
           [0028]      FIG. 2  illustrates one embodiment of the invention. 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0029]    6.1 General presentation 
         [0030]    As explained here above, the general principle of the invention is that of proposing a smartcard connector that directly integrates the card discharge means. More particularly, the card discharge means of the invention are an integral part of the memory card connector. This greatly simplifies the designing of this connector and extends the service life of the inserted cards. 
         [0031]    It is thus no longer necessary to add metal parts that enable the discharging of the card. The manufacturing of the memory card connector is therefore made easier. Besides, since the use of metal parts is not necessary with the invention, there is no risk of deterioration of the card when it is inserted or removed. The integrity of the card is therefore ensured. In addition, even in the case of corrective implementation, the invention does not require a major modification of the memory card connector. All that is needed is to add a part made of conductive plastic material. This is appreciably simpler than adding a metal strip. 
         [0032]    Such results are made possible according to the invention by the use of a semiconductor plastic to design the memory card connector. Naturally, the contribution of the invention is not limited to the use of a conductive plastic material. However, this design, which has been conceived by the inventors, has proved, during trials, to be far more efficient than anticipated. Indeed, the users felt that such a design could not meet problems of discharge. However, it has turned out that this design perfectly meets the problem and is simpler than the existing solutions. 
         [0033]    As mentioned, in order to reduce problems related to the addition of metal parts to the memory card connector, the invention proposes to build said memory card connector by using a connector at least partly made out of conductive plastic. 
         [0034]    The embodiments of the invention have characteristics suited to resolving the problems faced by the invention. 
         [0035]    Indeed, in order to enables a full discharge of the card, according to the embodiment, it is not sufficient to build the memory card connector partly with conductive plastic material. 
         [0036]    Thus, depending on the embodiment, it is important to define a value of surface resistance for the conductive plastic part. This value of resistance is expressed in Ω/square. The volume resistance is expressed in Ω/m (or Ω/cm). The surface resistance (which is important for the invention) is expressed in Ω/square. These terms related to “resistance” are commonly used by those skilled in the art. 
         [0037]    It varies depending on whether the entire memory card connector or only a portion of it is conductive. Here below, we present especially the case of two embodiments. It is clear however, that the invention is not limited to this particular application but can also be implemented in numerous other embodiments and more generally whenever the advantages procured by the invention are of interest. 
         [0000]    6.2 Description of embodiments 
       6.2.1 First Embodiment 
       [0038]    In a first embodiment, the memory card connector is equipped with a specific, relatively conductive part connected to the ground of the terminal. The resistance of this part is relatively low (of the order of a few hundreds of ohms). This is a configuration requiring little investment in terms of design. All that is necessary is to build a part that gets fixed to the memory card connector. This part is connected to the ground of the terminal. 
         [0039]    In this first embodiment, the part can be either over-molded or mounted subsequently (in the latter case, the material used does not need to have a very high temperature performance since it is not mounted on the surface of the printed circuit). 
         [0040]    Referring to  FIG. 2 , we present a first embodiment of a portion of a connector for a memory card according to the invention. 
         [0041]    The memory card connector  20  comprises an insertion module  21  with a generally rectangular parallelepiped shape. This insertion module  21  comprises an insertion slot  221  enabling the insertion of the card. The memory card connector  20  also comprises metal pins  22 . These metal pins  22  are positioned so as to come into contact with the contact zones of the chip situated on the card. In this embodiment, eight metal pins are used. The memory card connector  20  also comprises four pads  23  that are to be fixed a PCB receiving the memory card connector. In this embodiment, these four pads  23  are also connected to the ground of the terminal (by means of the PCB). 
         [0042]    According to the invention, in this embodiment, the memory card connector  20  additionally comprises a conductive plastic part  24  positioned on the insertion module  21 . This conductive plastic part  24  is shaped so as to be positioned at the inlet of the insertion slot  221  so that the chip of the chip card comes into contact with this conductive plastic part  24 . Besides, in this embodiment, the conductive plastic part  24  is shaped so that it does not contain any projecting ridge at the zone of contact with the card to enable smooth insertion. This makes it possible to avoid damaging the card when it is inserted. The conductive plastic part  24  furthermore comprises a linking rod  241 . This linking rod connects the conductive plastic part  24  to at least one connection to the ground of said connector. In the embodiment shown in  FIG. 2 , this connection is made on one of the four pads  23 . 
         [0043]    In this embodiment, the resistance of the conductive plastic part  24  is of the order of a few hundreds of thousands of ohms or even a few MΩ. The resistance should not be too low because that would cause a short circuit with the metal strips used to connect the card or at least there would be leakage resistance between the contacts. This would prevent the terminal from being approved by the official organizations (under the “Europay-MasterCard-VISA standard known as EMV). The resistance should not be too high because then the device would not be efficient during electrostatic discharges of a few kV. This means that the resistance should be balanced at about a few hundreds of kΩ across the contacts. 
       6.2.2 Second Embodiment 
       [0044]    In this second embodiment, it is the memory card connector that is fully made out of conductive material but at a very low level of conduction (the surface resistance of the material should be of the order of 10 5  to 10 6  Ω/square). 
         [0045]    Whether it is in the first or second embodiment, it is proposed to make parts out of one of the following known materials:
       SABIC Innovative Plastics LNP Stat-kon REP349 PA 66 (1.00e+7 to 1.00e+9 ohm/cm in values of volume resistance);   SABIC Innovative Plastics LNP Stat-kon LX04420C PEEK (1.00e+6 to 1.00e+8 ohm/cm in value of volume resistance);   Cool Polymers Coolpoly® D5502 Thermally Conductive Liquid Crystalline Polymer (1.00e+14 ohm/cm 1.00e+14 ohm/cm in value of volume resistance).       
 
         [0049]    In the second embodiment, the material in addition to having these electrical characteristics must withstand a re-melting temperature and wear and tear associated with the rubbing of the cards. 
       6.2.3 Third Embodiment 
       [0050]    In this embodiment, the discharge is carried out by the use of several parts made out of conductive plastic. The advantage of this embodiment is that it enables a gradual and non-aggressive discharge of the card. In this embodiment, the memory card connector comprises a plurality of parts made out of conductive plastic, each part made out of conductive plastic having a different surface resistance. 
         [0051]    In one particular implementation of this embodiment, a first part positioned at the inlet to the memory card connector has a surface resistance of the order of 10 12  Ω/square. A second part positioned inside the memory card connector has a surface resistance of the order of 10 10  Ω/square. This second part comes into contact with the card after the discharging carried out by the first part. A third part, positioned inside the memory card connector, has a surface resistance of the order of 10 8  Ω/square. 
         [0052]    This third part comes into contact with the card subsequently to the discharge carried out by the second part. Finally, according to one variant, the connector, in a zone situated just before the connector contacts, has a metal strip to finish the discharging of the card (this strip being connected to ground). Thus, rather than a sudden discharge of the card, the invention carries out a gradual discharge that can be complete and is even less likely to cause damage to the printed circuits. 
         [0053]    The number of discharge phases can thus extend from three to five levels, depending on the maximum charges against which it must be protected and the fragility of the electronic circuitry. 
         [0054]    Although the present disclosure has been described with reference to one or more examples, workers skilled in the art will recognize that changes may be made in form and detail without departing from the scope of the disclosure and/or the appended claims.