WO2001022535A1

WO2001022535A1 - Friction connector

Info

Publication number: WO2001022535A1
Application number: PCT/FR2000/002547
Authority: WO
Inventors: Patrick Le Gal
Original assignee: Ascom Monetel S.A.
Priority date: 1999-09-17
Filing date: 2000-09-14
Publication date: 2001-03-29
Also published as: AU7526000A; EP1085607A1; MXPA02002792A; EP1212812A1; EP1212812B1

Abstract

The invention concerns a friction connector (2) for smart card (12) comprising a frame (4) and at least a flexible contact (6) attached to the frame and comprising a convex contactor (8) whereof at least an electrical contact zone is designed to rest on a planar conductor chip of the smart card, the contact zone being, while it is being worn in a predetermined environment for use, moved relative to its initial position, wherein the contactor is mounted such that the initial position of its contact zone is offset relative to the centre of the chip in a direction opposite to said displacement direction.

Description

CONNECT TO FRICTION

The present invention relates to smart card connectors and in particular so-called "friction" connectors, used for example in smart card readers for payphones, payment terminals, sales machines and cash dispensers. The contactors of such connectors are designed to come into contact with conductive pads located on the surface of the chip 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 a smart card is inserted into the reader, the latter rubs against the contactors which thus undergo significant wear.

To improve the service life of conventional friction connectors, so-called "landing" systems have been created in which, in order to limit friction, the connectors are mounted on moving parts so that they are only in friction on limited races. However, these connectors are still subject to friction, which is moreover necessary since they have the advantage of cleaning the contactors and the contact pads, and thus ensuring good electrical contact. The present invention also applies to these landing connectors as well as, by example, to readers in which the insertion and removal of cards takes place in a motorized manner.

FIG. 1 is an extremely diagrammatic view of a sectional view of a connector 2 intended for a manual reader. The connector 2 comprises a frame 4 to which flexible blades 6a and 6b are fixed by first ends. The second opposite ends of the blades 6a and 6b each comprise a zone forming a contactor, respectively 8a and 8b, generally in the form of an ovoid cap, the convexity of which faces the surface to be contacted. The contactors 8a and 8b are provided for coming into contact with conductive pads 10a and 10b of a smart card 12. The smart card 12 is brought to a stop position, represented in FIG. 1. When the card 12 is in stop position, the conductive pads 10 are located just below the contactors 8. During the path of the card to the stop position, its front edge, then its surface and finally the conductive pads rub on the contactors 8. Des Similar rubs also take place when removing the card. During this movement, it may happen that the contactors are in contact with two adjacent pads at the same time. To prevent this from damaging the contents of the chip, the contactors 8 must be electrically deactivated when the card is swiped. To this end, the connector 2 is conventionally associated with a switch 14, provided for electrically activating or inactivating the contactors 8 depending on whether the card is in the stop position or not. The switch 14 is positioned so as to be closed by pressing the edge of the card when the latter arrives in the stop position, and to be open when the card 12 is withdrawn. A motorized reader systematically inactivates the contactors 8 before any movement of the card.

Figures 2A and 2B are respectively a sectional view 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 the card 12, in contact zones 16a and 16b. The contactors 8 here have a conventional shape of an 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, only two pads 10 of minimum size have been shown here, but it will be noted that a card conventionally comprises 6 or 8 pads. A different number of tablets can also be found in particular applications. Likewise, a connector conventionally comprises 6 to 8 flexible blades, and certain multi-standard connectors can comprise up to 16 flexible blades. It will also be noted that the dimensions and shapes of the contactors 8, shown here for information, may vary. FIG. 2B represents a top view of the elements of FIG. 2A. It is considered that the vertices of the contactors 8 are very slightly flattened from their first contact with the conductive pads. Thus, the contact zones 16 are represented as small, substantially circular zones centered on the tops of the contactors 8. The position of a contact zone will be referred to below as 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 have been worn out by the repeated insertion of cards. Each contactor 8 has a wear zone 20 resulting from friction on these cards. These wear zones are substantially flat, have a substantially elliptical contour, and extend substantially symmetrically on either side of the initial contact zone 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 pad. When the contact wear area increases 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 initial contact zone of the contactor, the position of the initial contact zones 16 is chosen at 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 risk causing short circuits between the pads on which they rest and neighboring elements of the card (such as other pads or conductive tracks), and the connector is replaced.

In a manual reader, a user can withdraw his card at any time, and provision must be made for each contactor to remain on the same conductive pad, as long as the switch 14 is not deactivated. This leads to defining a useful part of each conductive pad, which is the part of the pad in which the contact area must be, when the card is in abutment, to be always located on the same pad 10 at the time, at during the withdrawal of the card, the switch deactivates the contactor 8. In the example shown, the card 12 is inserted by swiping to the right and withdrawn by swiping to the left. If we consider that from the stop position, the card must be moved by a minimum stroke Dl 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 Dl from its right edge. In such a 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 pads. .

For reasons of clarity, we then consider the case of a minimum stroke Dl zero, in which the pellets conductive and their useful parts are combined, and the term "pellet" will designate the useful part of a pellet.

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

Thus, there remains a need for a connector which overcomes one or more of the disadvantages of conventional connectors. Thus, the present invention provides a friction connector 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 area of which is provided to rest on a flat conductive patch of the card. chip, the contact zone undergoing, during the wear of the contactor in a given environment of use, a displacement relative to its initial position, in which the contactor is mounted so that the initial position of its contact zone contact is offset from the center of the patch in a direction opposite to the direction of said movement.

According to one embodiment of the present invention, the flexible blade is fixed to the frame by a first end and comprises the contactor at its second end, and the initial position of the contact zone 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 initial positions of the contact zones 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 either side of the frame, and the distance between the initial positions of the contact zones is greater than the distance between the centers of the conductive pads .

The present invention also relates to a smart card reader provided with one of the preceding connectors. According to one embodiment of the present invention, the reader comprises means for bringing the contactors of the connector closer to the conductive pads so as to bring them into contact when the card is near the stop position and in the stop position. 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 zone of the connector contactor will undergo during its wear in a given environment of use, relative 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. 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: FIG. 1, previously described, schematically represents a sectional view of a connector of a manual reader bearing on a chip card in its stop position; FIGS. 2A and 2B, previously described schematically represent a sectional view and a top view of the conductive pads and contactors, not worn, of the connector of FIG. 1; Figures 3A and 3B, previously described, show the elements of Figures 2A and 2B when the contactors are worn; FIG. 3C represents the elements of FIG. 3B and the contact zones between the contactors and the conductive pads as highlighted by the inventor, • FIGS. 4A and 4B represent the same elements as FIGS. 2A and 2B for a connector according to the present invention, before contactor wear;

FIGS. 5A and 5B represent the same elements as FIGS. 4A and 4B, after wear of the contactors, -

Figures 6A and 6B show the same elements as Figures 4A and 4B, for a connector according to a variant of the present invention, before contactor wear; and Figures 7A and 7B show the same elements as Figures 6A and 6B, after wear of the contactors.

The same references designate the same elements in the following figures. Only the elements likely to facilitate comprehension have been represented, and the figures are not drawn to scale.

FIG. 3C represents, like FIG. 3B, conductive pads 10 on which contactors 8 worn based on a wear zone 20 rest. We have seen that it has hitherto been generally accepted that the entire surface of the zone wear 20, flat, rests on the conductive pad 10. Indeed, if we observe the wear area 20 of a contactor under a microscope, this area seems particularly flat. However, the inventor has 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 that it does not come into contact with the conductive pad 10 only in a contact area 22 of reduced size. The inventor has further demonstrated that with wear, the position of the zone 22 moves along the axis of the blade 6 towards the end of the blade which is fixed to the frame of the connector. Thus, in FIG. 3C, the positions of the contact zones 22a and 22b of the contactors 8a and 8b of the flexible blades 6a and 6b fixed by the right and by the left to the frame of the connector, are respectively shifted to the right and to the left relative to the positions of the initial contact zones 16a and 16b. It follows from these observations that, in order to determine whether a connector is too worn, the position of the wear zone 20 must not be considered, but rather that of the contact zone 22 on the pad 10. When, when the card is in abutment, the contact area 22 is outside the pad, the connector must be changed. Thus, the present invention provides for selecting the positions of the initial contact zones 16 of the contactors 8 of a connector so that the contact zones 22 remain 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 movement that the effective contact zone 22 will undergo during wear of the contactor. The ideal offset consists in providing an initial contact position in the immediate vicinity of the edge of the patch which is furthest from the end of the blade fixed to the frame. However, a safety margin must be kept because it must be taken into account that the initial wear of the contactor will cause the contact zone 22 to widen before it even undergoes a significant displacement. The establishment of such a margin is within the reach of the skilled person and it will not be described further.

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

FIGS. 5A and 5B show the same elements as FIGS. 4A and 4B respectively, after heavy wear of the contactors 8. The profile view of the wear zones 20 which are in fact non-planar has been shown very exaggerated. The contact zone 22a of the contactor 8a of the flexible blade 6a, fixed by the right to the frame of the connector, has moved to the right as the contactor 8a wears. In the example shown, the contact area 22a is located in the center of the conductive pad 10a. The contact zone 22b of the contactor 8b of the flexible blade 6b, symmetrically fixed to the blade 6a to the frame of the connector, has undergone a symmetrical development 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 pads 10. It will be necessary, to support the extension of the service life of a connector according to the present invention, cover the contactors 8 with an alloy of sufficient thickness or having the characteristics necessary to guarantee a good quality of electrical contact despite the additional wear of the contactors.

It will be noted that a connector with two rows of contactors has the surprising characteristic for a person skilled in the art of having a distance between the vertices of the contactors of the two rows which is different from the distance between the circles of the conductive pads, conventionally imposed by a standard. For reasons of simplicity, a connector is shown having two rows of contactors (8a and 8b) having symmetrical wear. In reality, for such a connector, the contactors of the flexible blades of one of the rows (a in the example shown) rub longer than those of the other row (b) during the insertion and removal of the cards, and their wear is greater. To take account of this phenomenon, the vertices of the contactors of the two rows will, according to the present invention, be offset asymmetrically with respect to the centers of the conductive pads, which constitutes another surprising feature of the present invention. In the case of a non-zero safety stroke D1, when the useful parts of the pads are distinct from the pads, the summits of the contactors will be offset asymmetrically with respect to the centers of the useful parts of the pads.

By way of example, we consider a connector such as that of FIG. 1 which corresponds to the ISO standard. Its blades are 10 mm long between the connector frame and the top of the contactors, and the connector is designed to rest on conductive pads whose centers are 7.62 mm apart. If we consider that the pellets are rectangles 2 mm long, that the safety stroke Dl is here non-zero and equal to 0.7 mm, that the contactors have the shape of an oval cap having a maximum radius of 2 , 5 mm, and if the card is removed to the left, the inventor has determined that the vertices of the contactors must be 7, 12 mm apart and that the plane of 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 susceptible to various variants and modifications which will appear to a person skilled in the art. In particular, the preceding description relates to a connector comprising blades fixed opposite the frame of the connector, but the person skilled in the art will easily adapt the The present invention has a connector whose flexible blades are fixed differently to the connector frame.

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

FIGS. 7A and 7B respectively represent the same elements as FIGS. 6A and 6B, after heavy wear of the contactors 8 of the flexible blades 6. With wear, the position of the contact zones 22 of the contactors 8 has shifted towards the left. In the example shown, the position of the contact zones 22 is in the middle of the pads 10, and the connector can still withstand heavy wear. It will be noted that in such a case a conventional connector can be used: it is sufficient, according to the present invention, to position the connector so that the contactors have the desired position relative to the card in the stop position. The preceding description was made for a connector in which the contactors of the same row have identical wear. It should be noted however that differences in wear may exist between the contactors of the same row. These differences are mainly due to lateral constraints in the readers. For example, during the insertion of the cards, they may be subjected to lateral stresses due to a spring provided for ejecting fraudulently inserted objects. It is in the spirit of the present invention to take these phenomena into account, and a person skilled in the art will easily adapt the present invention to a connector exhibiting such wear phenomena.

It will be noted that the construction parameters of a connector (its size, the materials used, the shape of the contactors) and of an associated reader intervene in the formation, the evolution and the displacement of the contact zone. electric when the contactors wear out. An optimal application of the present invention will take these parameters into account. Nevertheless, the present invention sets out simple principles which can be applied even without in-depth study of a given configuration while allowing a significant improvement in the service life of the connectors to be obtained. Thus, for a type of friction connector currently guaranteed for 100,000 card insertions, 300,000 insertions can be guaranteed by modifying the position of the connector contactors as previously indicated in accordance with the present invention.

Finally, a person skilled in the art will note that the present invention applies both to contactors having the shape of an ovoid cap elongated perpendicular to the direction of movement of the card as to contactors having the shape of an ovoid cap stretched in the direction of movement of the card.

Claims

1. 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) of which an electrical contact zone is provided to rest on a flat conductive patch of the smart card, the contact zone undergoing, during the wear of the contactor in a determined environment of use, a displacement relative to 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 a direction opposite to the direction of said movement.

2. friction connector (2) according to claim

1, the flexible blade (6) of which is fixed to the frame by a first end and includes the contactor (8) at its second end, characterized in that the initial position of the contact zone is located near the edge of the patch which is furthest from the first end of the blade.

3. 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 zones is less than the distance between the centers of the conductive pads .

4. friction connector according to claim 1 or 2, comprising at least two flexible blades (6a, 6b) fixed on either side of the frame (4), characterized in that the distance between the initial positions of the contact zones is greater than the distance between the centers of the conductive pads.

5. Chip card reader characterized in that it is provided with a connector according to any one of claims 1 to 4.

6. Smart card reader according to claim 5, characterized in that it comprises means for bringing the contactors closer to the connector of the conductive pads so as to bring them into contact when the card is near the stop position and in the stop position.

7. A method of manufacturing a friction connector comprising the steps of: 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, with respect to a 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.