EP1085607A1 - Friction connector - Google Patents

Abstract

The friction connector construction has flexible strips (6) with a convex contact shape (8) attached to a main body which contacts a conductor pad (10a) on an integrated circuit. The contact is mounted so that during use the contact takes up the slack to compensate for wear.

Description

The present invention relates to connectors for smart cards and in particular connectors known as "to rubbing ", used for example in card readers payphone chips, payment terminals, payment machines sales and ATMs. Contactors of such connectors are provided to come into contact with pads conductive located on the surface of the smart card and corresponding to the terminals of the chip, so as to connect these terminals to the electronic circuits of the reader which can then process the information contained in the chip. When introducing a smart card in the reader, the latter comes to rub on contactors which thus undergo significant wear.

To improve the service life of connectors to conventional friction, we created systems called "landing" in which, in order to limit friction, the connectors are mounted on moving parts so as not to find in friction only on limited strokes. However, these connectors are always subjected to friction, which is moreover necessary because they have the advantage of cleaning contactors and contact pads, and thereby ensuring good electrical contact. The present invention applies also to these landing connectors as well as by example, to readers in which insertion and removal cards take place in a motorized manner.

Figure 1 shows in an extremely schematic way a sectional view of a connector 2 intended for a reader manual. Connector 2 includes a frame 4 to which blades flexible 6a and 6b are fixed by first ends. The second opposite ends of the blades 6a and 6b have each a zone forming a contactor, respectively 8a and 8b, generally in the shape of an ovoid cap whose convexity is facing the surface to be contacted. Contactors 8a and 8b are intended to come into contact with pellets conductors 10a and 10b of a smart card 12. The smart card 12 is brought to a stop position, shown in Figure 1. When the card 12 is in the stop position, the pads conductors 10 are located just below the contactors 8. When the card travels to the stop position, its front edge, then its surface and finally the conductive pads rub on contactors 8. Similar friction has also takes place when the card is withdrawn. During this displacement, it may happen that the contactors are in contact with two neighboring pellets at the same time. To prevent this does not damage the content of the chip, the contactors 8 must be electrically disabled when swiping the card. AT To this end, connector 2 is conventionally associated with a switch 14, intended to activate or deactivate electrically the contactors 8 depending on whether the card is in the stop position or no. The switch 14 is positioned so as to be closed by pressure from the edge of the card when it arrives in the stop position, and to be opened when the card 12 is withdrawn. A motorized reader systematically inactivates contactors 8 before moving the card.

FIGS. 2A and 2B are respectively a view in section and a top view of the contactors 8 resting on the conductive pads 10 of the card 12 in the stop position.

FIG. 2A represents contactors 8a and 8b, placed on pads 10a and 10b of card 12, in areas of contact 16a and 16b. The contactors 8 have here a conventional shape ovoid cap, formed by stamping the ends of the blades 6a and 6b. The minimum size of the pellets 10 is fixed by an international standard (ISO). For reasons of clarity, we represented here only two pellets 10 of minimum size, but it will be noted that a card conventionally comprises 6 or 8 pads. You can also find a different number of tablets in particular applications. Similarly, a connector includes typically 6 to 8 flexible blades, and some multi-standard connectors can include up to 16 flexible blades. We will note also that the dimensions and the shapes of the contactors 8, shown here for illustrative purposes, may vary.

Figure 2B shows a top view of the elements of Figure 2A. We consider that the vertices of the contactors 8 are very slightly flattened from their first contact with conductive pads. Thus, the contact zones 16 are represented as small, substantially circular areas centered on the vertices of the contactors 8. We will call by the following position of a contact zone, its position when the card is in abutment.

FIGS. 3A and 3B respectively represent the same elements as FIGS. 2A and 2B after the contactors 8 were worn out by the repeated introduction of cards. Each contactor 8 has a wear area 20 resulting from friction on these cards. These wear zones are substantially flat, have a substantially elliptical outline, and extend substantially symmetrically on either side of the initial contact area 16 of the contactor.

In the current state of the art, it is considered that the entire surface of a wear zone 20 is in contact with the corresponding tablet. When the wear area of the contactors grows beyond a certain limit, the connector must be exchange. This limit depends in particular on the type of reader used, motorized or manual.

In a motorized reader, the wear zone extending substantially symmetrically on either side of the area of initial contact of the contactor, the position of the zones is chosen initial contact 16 in the center of the conductive pads. Thus, the contactors can be used until their wear zone extends to the edges of the contact pads. Then the contactors may cause short circuits between the pads on which they rest and neighboring elements of the map (such as other pads or conductive tracks), and the connector is replaced.

In a manual reader, a user can at any instant withdraw his card, and it is necessary to envisage that each contactor remains on the same conductive pad, as long as the switch 14 is not inactive. This leads to define a useful part of each conductive pad, which is the part of the pad in which the contact area must be located, when the card is in abutment, to be always located on the same patch 10 at the time when, during the withdrawal of the card, the switch deactivates contactor 8. In the example shown, the card 12 is inserted by sliding towards the right and removed by swiping to the left. If we considers that from the stop position, the card must be moved a minimum stroke D1 to the left so that the switch 14 is open, the useful part of a pad 10 will consist of all the part of the patch located between its left edge and a distance D1 from its right edge. In such reader, the position of the initial contact areas 16 is chosen at the center of the useful parts of the conductive pads, and the connector is changed when the wear area of its contactors extends to the edge of the useful parts of the lozenges.

For reasons of clarity, we then consider the case of a zero D1 minimum stroke, in which the pads conductive and their useful parts are confused, and we will denote by the term "tablet" the useful part of a tablet.

We have seen that a friction connector must be changed after a number of insertions. There is a need for a connector that supports a greater number of insertions of cards before needing to be changed. A classic solution consists of using a special alloy for contactors 8 particularly resistant to wear and having good Electrical Specifications. However, the use of such alloy significantly increases the cost of the connector. In addition, a such a solution risks making the contactors particularly abrasive and to wear the conductive pads of smart cards faster, which can lead to connection faults and make unusable large chip cards number of insertions (bank card, electronic wallet, etc.).

Thus, there remains a need for a connector overcoming one or more of the disadvantages of connectors classics.

Thus, the present invention provides a connector to friction for a smart card comprising a frame and at least one flexible blade fixed to the frame and which comprises a convex contactor an electrical contact zone is provided to rest on a flat conductive patch of the smart card, the area of contact undergoing, during wear of the contactor in a determined environment of use, displacement compared in its initial position, in which the contactor is mounted so that the initial position of its contact area is offset with respect to the center of the patch in a direction opposite to the direction of said displacement.

According to an embodiment of the present invention, the flexible blade is fixed to the frame by a first end and has the contactor at its second end, and the position initial contact area is located near the edge of the pad which is furthest from the first end of the blade.

According to an embodiment of the present invention, the connector comprises at least two flexible blades fixed to opposite sides of the frame, and the distance between the positions initial contact areas is less than the distance between the centers of the conductive pads.

According to an embodiment of the present invention, the connector comprises at least two flexible blades fixed on the side on either side of the frame, and the distance between the initial positions contact areas is greater than the distance between the centers of the conductive pads.

The present invention also relates to a reader for smart card with one of the previous connectors.

According to an embodiment of the present invention, the reader includes means for bringing the contactors closer to the connector of the conductive pads so as to bring them in contact when the card is close to the stop position and in the stop position.

déterminer le sens du déplacement que va subir la zone de contact électrique du contacteur du connecteur lors de son usure dans un environnement d'utilisation déterminé, par rapport à une position initiale, et

monter le contacteur de sorte que la position initiale de sa zone de contact est décalée dans un sens opposé au sens dudit déplacement de la zone de contact électrique.

The present invention also relates to a method of manufacturing a friction connector comprising the steps consisting in:

determining the direction of movement that the electrical contact area of the connector contactor will undergo during its wear in a given environment of use, compared to an initial position, and

mount the contactor so that the initial position of its contact area is offset in a direction opposite to the direction of said movement of the electrical contact area.

la figure 1 précédemment décrite, représente schématiquement une vue en coupe d'un connecteur d'un lecteur manuel portant sur une carte à puce dans sa position de butée ;

les figures 2A et 2B, précédemment décrites représentent schématiquement une vue en coupe et une vue de dessus des pastilles conductrices et des contacteurs, non usés, du connecteur de la figure 1 ;

les figures 3A et 3B, précédemment décrites, représentent les éléments des figures 2A et 2B lorsque les contacteurs sont usés ;

la figure 3C représente les éléments de la figure 3B et les zones de contact entre les contacteurs et les pastilles conductrices telles que mises en évidence par l'inventeur ;

les figures 4A et 4B représentent de mêmes éléments que les figures 2A et 2B pour un connecteur selon la présente invention, avant usure des contacteurs ;

Les figures 5A et 5B représentent de mêmes éléments que les figures 4A et 4B, après usure des contacteurs ;

Les figures 6A et 6B représentent de mêmes éléments que les figures 4A et 4B, pour un connecteur selon une variante de la présente invention, avant usure des contacteurs ; et

les figures 7A et 7B représentent de mêmes éléments que les figures 6A et 6B, après usure des contacteurs.

These objects, characteristics and advantages, as well as others of the present invention will be explained in detail in the following description of particular embodiments given without limitation in relation to the attached figures among which:

Figure 1 previously described, schematically shows a sectional view of a connector of a manual reader on a smart card in its stop position;

Figures 2A and 2B, previously described schematically show a sectional view and a top view of the conductive pads and contactors, not worn, of the connector of Figure 1;

Figures 3A and 3B, previously described, show the elements of Figures 2A and 2B when the contactors are worn;

Figure 3C shows the elements of Figure 3B and the contact areas between the contactors and the conductive pads as highlighted by the inventor;

FIGS. 4A and 4B show the same elements as FIGS. 2A and 2B for a connector according to the present invention, before wear of the contactors;

Figures 5A and 5B show the same elements as Figures 4A and 4B, after wear of the contactors;

FIGS. 6A and 6B show the same elements as FIGS. 4A and 4B, for a connector according to a variant of the present invention, before wear of the contactors; and

Figures 7A and 7B show the same elements as Figures 6A and 6B, after wear of the contactors.

Same references denote same items in following figures. Only elements likely to facilitate understanding have been represented, and the figures are not drawn to scale.

FIG. 3C represents, like FIG. 3B, conductive pads 10 on which contactors rest 8 worn according to a wear zone 20. We have seen that it was up to commonly accepted present that the entire area of the wear area 20, flat, rests on the conductive pad 10. Indeed, if the wear area 20 of a contactor is observed under a microscope, this area seems particularly flat. However, the inventor highlighted, by means of special contact cards including the conductive pads are composed of a large number of conductive strips insulated from each other and each connected to a light emitting diode, that the wear zone 20 is not perfectly flat and does not come into contact with the pellet conductive 10 than in a contact area 22 of reduced size. The inventor further demonstrated that with wear, the position of zone 22 moves along the axis of blade 6 towards the end of the blade which is fixed to the connector frame. Thus, in FIG. 3C, the positions of the contact zones 22a and 22b of contactors 8a and 8b of flexible blades 6a and 6b fixed from the right and from the left to the connector frame, are respectively shifted to the right and left with respect to positions of the initial contact zones 16a and 16b. It results from these observations that to determine if a connector is too worn, we should not consider the position of the area wear 20, but rather that of the contact zone 22 on the when 10. when the card is in abutment, the area of contact 22 is outside the patch, the connector must be exchange.

Thus, the present invention provides for selecting the positions of the initial contact zones 16 of the contactors 8 a connector so that the contact areas 22 remain the as long as possible inside the conductive pads 10 despite the wear of the contactors. The principle of the invention is therefore to shift the position of the initial contact zone of the new contactor on the pad in a direction opposite to the displacement that the effective contact zone 22 will undergo during contactor wear. The ideal offset is to plan for a initial contact position in the immediate vicinity of the edge of the pad which is furthest from the end of the attached blade to the frame. However, you must keep a safety margin because it take into account that the initial wear of the contactor will cause a widening of the contact zone 22 even before that this one does not undergo a significant displacement. The establishment of such a margin is within the reach of the man of the trade and it will not be described further.

Figures 4A and 4B show the same elements as FIGS. 2A and 2B for a connector according to the present invention, before contactor wear 8. The card is in the position stop. The contactor 8b of the flexible blade 6b, fixed from the left to the connector frame, bears on the conductive pad 10b in an initial contact area 16b located near the right edge tablet 10b. The initial contact area 16a of the contactor 8a of the flexible blade 6a, fixed by the right to the frame, is located at near the left edge of the patch 10a.

FIGS. 5A and 5B represent the same elements as FIGS. 4A and 4B respectively, after heavy wear of the contactors 8. The view of profile of the wear zones 20 which are in fact non-planar. The area contact 22a of the contactor 8a of the flexible blade 6a, fixed by the right to the connector frame, moved to the right at as the contactor 8a wears. In the example shown, the contact area 22a is in the center of the conductive pad 10a. Contact area 22b of contactor 8b of the flexible blade 6b, symmetrically fixed to the blade 6a to the frame of the connector, has undergone a symmetrical evolution to that of the zone 22a. In the case shown, the contactors 8 can still undergo heavy wear before their contact zones 22 come out of the pellets 10. It will be necessary, to accompany the extension of the service life of a connector according to this invention, to cover the contactors 8 with an alloy of a sufficient thickness or having the necessary characteristics to guarantee good quality electrical contact despite additional wear of the contactors.

Note that a connector with two rows of contactors has the surprising feature for the man of the job of having a distance between the summits of the contactors of the two rows which is different from the distance between the midpoints conductive pads, conventionally imposed by a standard.

For reasons of simplicity, a connector having two rows of contactors (8a and 8b) with symmetrical wear. In reality, for such connector, the contactors of the flexible blades of one of the rows (a in the example shown) rub longer than those on the other row (b) when inserting and removing cards, and their wear is greater. To take into account this phenomenon, the vertices of the contactors of the two rows will, according to the present invention, not symmetrically offset with respect to the centers of the conductive pads, which is another surprising feature of this invention. In the case of a non-zero safety stroke D1, when the useful parts of the pellets are distinct from pads, the tops of the contactors will be shifted not symmetrically with respect to the centers of the useful parts of lozenges.

As an example, consider a connector such as that of Figure 1 which corresponds to the ISO standard. Its blades are 10 mm long between the connector frame and the top contactors, and the connector is designed to rest on conductive pads with centers 7.62mm apart. If we consider that the pellets are rectangles of 2 mm long, that the safety stroke D1 is here non-zero and equal 0.7 mm, that the contactors have an ovoid cap shape with a maximum radius of 2.5 mm, and if the removal of the card done to the left, the inventor determined that tops of contactors must be 7.12mm apart and the symmetry of the contactors must be offset by 0.46 mm to the left of the plane of symmetry of the conductive pads.

Of course, the present invention is capable of various variants and modifications which will appear to the man of the job. In particular, the preceding description relates to a connector comprising blades fixed facing the frame of the connector, but those skilled in the art will easily adapt the present invention has a connector whose flexible blades are differently attached to the connector frame.

Figures 6A and 6B thus illustrate the same elements as FIGS. 4A and 4B respectively, for a connector whose the flexible blades 6a and 6b are each fixed from the left to the connector frame. The initial contact zones 16a and 16b have, according to the present invention, both been shifted to right of the pads 10a and 10b.

Figures 7A and 7B show respectively same elements as FIGS. 6A and 6B, after heavy wear of the contactors 8 of the flexible blades 6. With wear, the position contact zones 22 of contactors 8 has moved towards the left. In the example shown, the position of the contact 22 is in the middle of the pads 10, and the connector can still withstand heavy wear. Note that in such a case we can use a classic connector: it suffices, according to the present invention, to position the connector so that the contactors have the desired position relative to the card in stop position.

The above description was made for a connector in which the contactors in the same row have a identical wear. Note, however, that differences in wear may exist between contactors in the same row. These differences are mainly due to lateral constraints in readers. For example, when inserting cards, these can be subjected to lateral stresses due to a spring provided for ejecting fraudulently inserted objects. he it is in the spirit of the present invention to take account of these phenomena, and the skilled person will easily adapt the present invention to a connector having such phenomena of wear.

Note that the construction parameters of a connector (its size, the materials used, the shape of the contactors) and an associated reader are involved in formation, evolution and displacement of the contact area electric when the contactors wear out. An application optimal of the present invention will take into account these settings. Nevertheless, the present invention sets out principles simple that can be applied even without further study of a given configuration while allowing to obtain a significant improvement in the service life of connectors. So, for a type of friction connector currently guaranteed at 100,000 card inserts, we can guarantee 300,000 inserts by changing the position of the connector contactors as previously indicated in accordance with the present invention.

Finally, those skilled in the art will note that the present invention also applies to contactors having the form an ovoid cap elongated perpendicular to the direction of displacement of the card only to contactors having the form of a ovoid cap elongated in the direction of movement of the card.

Claims (7)

Friction connector (2) for smart card (12) comprising a frame (4) and at least one flexible blade (6) fixed to the frame and which comprises a convex contactor (8) including a zone of electrical contact is provided to rest on a pad flat conductor of the smart card, the contact area undergoing, during wear of the contactor in a determined environment of use, displacement compared in its initial position, characterized in that the contactor is mounted so that the initial position of its contact area is offset from the center of the patch in an opposite direction in the sense of said displacement. Friction connector (2) according to claim 1, the flexible blade (6) of which is fixed to the frame by a first end and comprises the contactor (8) at its second end, characterized in that the initial position of the contact area is located near the edge of the patch which is the most away from the first end of the blade. Friction connector according to claim 1 or 2, comprising at least two flexible blades (6a, 6b) fixed to opposite sides of the frame (4), characterized in that the distance between the initial positions of the contact areas is less at the distance between the centers of the conductive pads. Friction connector according to claim 1 or 2, comprising at least two flexible blades (6a, 6b) fixed on the side and on the other side of the frame (4), characterized in that the distance between the initial positions of the contact areas is greater than the distance between the centers of the conductive pads. Smart card reader characterized in that it is provided with a connector according to any one of claims 1 to 4. Smart card reader according to claim 5, characterized in that it includes means for bringing the contactors of the connector of the conductive pads so as to bring them into contact when the card is near the stop position and in stop position. Method for manufacturing a friction connector comprising the steps consisting in: determining the direction of movement that the electrical contact area of the connector contactor will undergo during its wear in a given environment of use, compared to an initial position, and mount the contactor so that the initial position of its contact area is offset in a direction opposite to the direction of said movement of the electrical contact area.

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