MXPA02002792A

MXPA02002792A - Friction connector.

Info

Publication number: MXPA02002792A
Application number: MXPA02002792A
Authority: MX
Inventors: Le Gal Patrick
Original assignee: Ascom Monetel Sa
Priority date: 1999-09-17
Filing date: 2000-09-14
Publication date: 2002-07-22
Also published as: EP1085607A1; EP1212812A1; AU7526000A; EP1212812B1; WO2001022535A1

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

FRICTION CONNECTOR The present invention relates to the connectors of smart cards and in particular to the so-called "friction connectors", used for example in public telephones, payment terminals, vending machines and smart card readers cash dispensers. The contactors of these connectors are provided to make contact with the conductive protectors located on the surface of the smart card and correspond to the terminals of the integrated circuits, to connect these terminals to the electronic circuits of the reader that can then process the information contained in the (chips) integrated circuits. By inserting a smart card into the reader, the card rubs against the contactors that are then subjected to significant wear. To improve the service life of conventional friction connectors, so-called "grounded" systems have been created in which, to limit friction, the connectors are assembled on moving components to only touch on limited journeys. However, the connectors are still subjected to friction, which is also necessary since it has the advantage of cleg contactors and contact protectors and therefore ensures a good electrical contact. The present invention also applies to such landed connectors as well as, for example, to sensors in which the insertion and recovery of the card is motorized. Fig. 1 very schematically shows a connector 2 designed for a manual reader. The connector 2 includes a frame 4 in which the flexible blades 6a and 6b are joined to the first X ü terminals. The second opposite ends of the blades 6a and 6b each include an area forming a contactor, respectively 8a and 8b, generally in the form of an ovoid lid, the convexity of the faces of the surface to be contacted. Contactors 8a and 8b are provided to contact the conductive shields 10a and 10b of a smart card 12. The smart card 12 is brought to a pushing position, shown in Fig. 1. When the card 12 is in the position of push, the conductive guards 10 are located simply under the contactors 8. During the trip of the card to its pushing position, its leading edge, then its surface and finally the conductive guards, rub against the contactors 8. A similar friction also occurs in the recovery of the card. During this travel, the contactors may sometimes be in contact with two adjacent protectors. To prevent this from damaging the integrated circuit, the contactors 8 must be electrically deactivated during the sliding of the card. For this purpose, the connector 2 is conventionally associated with a switch 14, provided for electrically activating or deactivating the contactors 8 according to whether the card is in the thrust position or not. The switch 14 is positioned to be closed by pressing the edge of the card when said card reaches the push position and to open when the card 12 is recovered. A motorized reader systematically deactivates the contactors 8 before any displacement of the card. Figures 2A and 2B are respectively a cross-sectional view and a top view of the contactors 8 resting on the conductive shields 10 of the card 12 in the pushing position. Figure 2A shows the contactors 8a and 8b, installed in the protectors 10a and 10b of the card 12, in the contact areas 16a and 16b. The contactors 8 have here a conventional ovoid cap shape, which is formed by enhancing the blade ends 6a and 6b. The minimum size of the protectors 10 is determined by an international standard (ISO). For clarity, only two minimum measurement protectors 10 are shown here, but it should be noted that a card conventionally includes 6 or 8 protectors. A different number of protectors can also be found in specific applications. Similarly, a connector conventionally includes 6 to 8 flexible blades and some standard multiple connectors may include more than 16 flexible blades. It should also be noted that the dimensions and shapes of the contactors 8, which are shown here as an example, may vary.

Fig. 2B shows a top view of the elements of Fig. 2A. It is assumed that the upper parts of the contactors 8 are slightly flattened as soon as they make their first contact with the conductive protectors. Therefore, the contact areas 16 are substantially shown as small round areas centered on the upper part of the contactor 8. In the future, "the position of a contact area" will designate its position when the card is in the position of push. Figures 3A and 3B respectively show the same elements as Figures 2A and 2B after the touchs 8 have been damaged by the repeated introduction of cards. Each connector 8 exhibits a damaged area 20 which is the result of friction against the cards. The damaged areas are substantially smoothed, they have a substantially elliptical contour and extend substantially symmetrically on either side of the initial contact area 16 of the contactor. In the present state of the art, it is assumed that the total area of a damaged area 20 is in contact with the corresponding protector. When the damaged area of the contactors increases beyond a given limit, the connector must be changed. This limit depends, in particular, on the type of reader used, whether it is motorized or manual. In a motorized reader, since the damaged area substantially and symmetrically extends on either side of the initial contact area of the contactor, the position of the initial contact area 16 is chosen to be at the center of the conductive shields. Therefore, the contactors can be used until their damaged area extends to the edge of the contact protectors. Then, contactors are endangered by causing short circuits between the protectors on which they rest and the neighboring elements of the card (such as other protectors or conductive tracks) and the connector is replaced. In a manual reader, a user can retrieve their card at any time and each contactor must be maintained to remain in the same conductive protector, while switch 14 is not activated. This allows to define a useful portion of each conductive protector, which is the portion of protector in whose contact area it must be located, when the card is in the push position, it will always be located in the same protector 10 at the moment when, during the recovery of the card, the switch deactivates the contactor 8. In the example shown, the card 12 is inserted by sliding it to the right and is recovered by sliding it to the left. Assuming that from the push position, the card must move through a minimum trip D1 to the left for the switch 14 to be opened, the useful portion of a protector 10 will consist of the total portion of the protector located between its left edge and a distance D1 from its right edge. In such a reader, the position of the initial contact areas 16 is chosen to be at the center of the useful portions of the conductive shields and the connector is changed when the damaged area of its contactors extends to the edge of the useful portions of the shields . For clarity, below is considered the case of a null minimum trip D1, in which the conductive shields and their useful areas are confused and the "protector" will now be named as the useful portion of a shield. It has been seen that a friction connector must be changed after a given number of inserts. There is a need for a connector that can withstand a greater number of card inserts before it needs to be changed. A conventional solution consists in using for the contactors 8 a special alloy which is particularly resistant to wear and which has good electrical characteristics. However, the use of such an alloy substantially increases the cost of the connector. Additionally, such a solution runs the risk of making the contactors particularly abrasive and wear out the conductive protectors of the smart cards more quickly., which can result in electrical connection defects and make the smart cards require a greater number of inserts (credit card, electronic bag, etc.) unusable. Therefore, there is a need for a connector that overcomes one or more of the disadvantages of conventional connectors. Therefore, the present invention provides a friction connector for a smart card that includes a frame and at least one flexible blade attached to the frame and that includes a convex contactor, an electrical contact area which is provided to rest on a conductive protector of the flat smart card, the contact area subjected, during the wear of the contactor in a given use environment, a displacement with respect to its initial position, in which the contactor is assembled so that the initial position of its area of contact is changed with respect to the center of the protector in the opposite direction to the direction of said displacement. In accordance with one embodiment of the present invention, the flexible blade is attached to the frame by a first end and includes the contactor at its second end and the initial position of the contact area is located in the vicinity of the edge of the protector that is furthest from the first end of the blade. According to one embodiment of the present invention the connector includes at least two flexible blades attached to opposite sides of the frame and the distance between the initial positions of the contact areas is less than the distance between the centers of the conductive shields. According to one embodiment of the present invention, the connector includes at least two flexible blades attached to another side of the frame and the distance between the initial positions of the contact areas is greater than the distance between the centers of the conductive shields. The present invention also proposes a smart card reader provided with one of the preceding connectors.

In accordance with one embodiment of the present invention, the reader includes means for bringing the contactors of the connector of the closest conductive protectors, to have them in contact when the card is close to the thrust position and in the thrust position. The present invention also proposes a method for manufacturing a friction connector that includes the steps of: determining the direction of displacement that the electrical contact area of the connector contactor will suffer during its wear in a given use environment, with respect to a position start and assemble the contactor so that the initial position of its contact area is changed in a direction opposite to the direction of said displacement of the electrical contact area. These and other objects, features and advantages of the present invention will be discussed in detail in the following non-limiting description of the specific embodiments in connection with the accompanying drawings, in which the: Fig. 1, previously described, schematically shows a view of the cross section of a connector of a manual reader holding a smart card in its push position; Figures 2a and 2b, previously described, schematically show a cross-sectional view and a top view of the undamaged conductive and contactor shields of the connector of Fig. 1; Figures 3A and 3B, previously described, show the elements of Figures 2A and 2B when the contactors are damaged; Fig.3C shows the elements of Fig. 3B and the contact areas between the contactors and the conductive shields as disclosed by the present inventor; Figures 4A and 4B show the same elements as Figures 2A and 2B for a connector in accordance with the present invention, before the contactors are damaged; Figures 5A and 5B show the same elements as Figures 4A and 4B after the wear of the contactors; Figures 6A and 6B show the same elements as Figures 4A and 4B, for a connector in accordance with an alternative of the present invention, before the touchs are damaged; Y . Figures 7A and 7B show the same elements as Figures 6A and 6B, after the wear of the contactors. The same references designate the same elements in the following drawings. Only those similar elements that are likely to facilitate understanding have been shown, and the drawings are not to scale. Fig.3C shows, as in Fig. 3B, the conductive shields 10 on which the contactors 8 rest, the deterioration along a damaged area 20. It has been seen that it was commonly admitted that the total area of the damaged area 20, which is smoothed, rests on the conductive shields 10. In fact, the damaged area of a contactor appears to be particularly flat as viewed from a microscope. . However, the present inventor has shown, by means of special contact cards, that the conductive shields which are formed of a large number of conductive strips isolated from each other and each connected to a light-emitting diode, that the damaged area 90 is not perfectly flat and only contacts the protector 10 in a contact area 22 of reduced size. The present inventor has further shown that with wear, the position of the area 22 moves along the blade axis 6 towards the end of the blade which is attached to the frame of the connector. Therefore, in Fig.3C, the positions of the contact areas 22a and 22b of the contactors 8a and 8b of the flexible blades 6a and 6b attached to the right and to the left of the connector frame are respectively changed to the right and to the left with respect to the position of the initial contact areas 16a and 16b. These observations result in that, in order to determine whether a connector is too damaged, the position of the contact area 22 in the shield 10 has to be considered in place of that of the damaged area 20. When, such as the card is in the position of push, the contact area 22 is outside the protector, the connector must be changed.

Therefore, the present invention includes selecting the positions of the initial contact areas 16 of the contactors 8 of a connector so that the contact areas 22 remain as far as possible within the conductive shields 10 despite the wear of the contactors. . The principle of the present invention is accordingly to change the position of the initial contact area of the new protector contactor in a direction opposite to the displacement that the effective contact area 22 will suffer during the wear of the contactor. The ideal replacement is to provide an initial contact position in the immediate vicinity of the rotector edge that is very distant from the end of the blade attached to the frame. However, a safety margin must be maintained, therefore it must be taken into account, the fact that the initial wear of the contactor will extend the contact area 22 even before said area is significantly displaced. The establishment of said margin is within the abilities of those skilled in the art and none will be described further. Figures 4A and 4E show the same elements as Figures 2A and 2B for a connector in accordance with the present invention, before the contactors wear 8. The card is in the push position. The contactor 8b of the flexible blade 6b, connected at its left end to the frame of the connector, presses against the conductive protector 10b in an initial contact area 16b located near the right edge of the protector 10b. The initial contact area 16 a of contactor 8 a of flexible blade 6 a, attached at its right end to the frame, is close to the left edge of protector 10 a.

Figures 5A and 5B show the same elements as Figures 4A and 4b respectively, after a strong wear of the contactors 8. The side view of the damaged areas 20, which in fact are not flat, have been shown from a very exaggerated way. The contact area 22a of the contactor 8a of the flexible blade 6a, joined at its right end to the frame of the connector, has moved to the right along the wear of the contactor 8a. In the example shown, the contact area 22a is in the center of the conductive protector 10a. The contact area 22b of the contactor 8b of the flexible blade 6b, symmetrically joined to the blade 6a of the connector frame, has progressed symmetrically to the area 22a. In the case shown, the contactors 8 can still be subjected to heavy wear before their contact areas 22 leave the protectors 10. It will be necessary, in order to accompany the extension of the useful life of a connector in accordance with the present invention. , cover the contactors 8 with an alloy of a sufficient thickness or having the necessary characteristics to guarantee a good quality of electrical contact despite the additional wear of the contactors. It should be noted that a connector with two rows of contactors has the surprising peculiarity for those skilled in the art, having a distance between the upper parts of the contactors of the two rows, which is conventionally different from the distance between the means of the protectors. conductive, conventionally imposed by a standard.

For simplicity, a connector is shown having two rows of contactors (8a and 8b) exhibiting symmetrical wear. Actually, for such connector, the contactors of the flexible blades of one of the rows (a in the example shown) rubs much more than those of the second row (b) during the insertion and recovery of the cards and their wear is greater . To take this phenomenon into account, the upper parts of the contactors of both rows will, in accordance with the present invention, be asymmetrically changed with respect to the centers of the conductive protectors, which is another surprising feature of the present invention. In the case of a non-zero safety trip D1, when the useful portions of the protectors are different from the protectors, the upper parts of the contactors will not be asymmetrically changed with respect to the centers of the useful portions of the protectors. As an example, a connector like that in Fig. 1, which corresponds to the ISO standard, is considered. That its blades have a length of 10-mm between the connector of the frame and the upper part of the contactors and prepares the connector to rest on the conductive protectors, the centers of which are distant by 7.62 mm. Assuming that the protectors are rectangles with a length of 2-mm, that safety trip D1 here is non-zero and equal to 0.7 mm, that the contactors are formed as an ovoid lid with a maximum radius of 2.5 mm and that the card recovery is performed on the left, the present inventor has determined that the upper parts of the contactors should be distant by 7.12 mm and that the plane of symmetry of the contactors should be changed by 0.46 mm to the left of the plane of symmetry of the conductive protectors. Of course, it is likely that the present invention will have various alterations, modifications and improvements that will rapidly occur to those skilled in the art. In particular, the above description relates to a connector that includes blades oppositely attached to the frame of the connector, but those skilled will readily adapt the technique of the present invention to a connector, the flexible blades which bind differently to the frame of the connector. Figures 6A and 6B thus illustrate the same elements, as Figures 4A and 4B, respectively, for a connector having its flexible blades 6a and 6b each joined at its left end to the frame of the connector. The initial contact areas 16a and 16b have, in accordance with the present invention, both been changed to the right of the shields 10a and 10b. Figures 7A and 7B respectively show the same elements as Figures 6A and 6B, after a strong wear of the contactors 8 of the flexible blades 6. With wear, the position of the contact areas 22 of the contactors 8 has been moved to the left. In the example shown, the position of the contact areas 22 is in the middle area of the shields 10 and the connector can still overcome a strong wear. It should be noted, that in such a case, a conventional connector can be used: it is sufficient, in accordance with the present invention, to position the connector so that the contactors have the desired position with respect to the card in the pushing position. The above description has been made for a connector in which the contactors of the same row have an identical wear. It should be noted however that differences in wear can exist between the contactors of the same row. These differences are mainly due to the lateral tension in the readers. For example, in the insertion of the cards, said cards may be subjected to lateral effort due to a spring designed to eject fraudulently inserted objects. It is within the spirit of the present invention to have such phenomena considered and those skilled in the art will readily adapt the present invention to a connector exhibiting such wear phenomena. It should be noted that the construction parameters of such connector (its size, the materials used, the shape of the contactors) and of an associated reader are involved in the formation, progress and displacement of the electrical contact area in the wear and tear of the c ontactors. A pplication or optics of the present invention will take these phenomena into account. However, the present invention discovers simple principles that can even be applied without any complete study or a given configuration while obtaining a substantial improvement in the useful life of the connectors. Thus, for a friction connector currently guaranteed for 100,000 insertions of the card, 300,000 inserts can be guaranteed by modifying the position of the connector contactors, as previously indicated in accordance with the present invention. Finally, those skilled in the art should note that the present invention applies to contactors having the shape of an ovoid cap extending perpendicularly in the direction of travel of the card, also as contactors formed as an ovoid cap extending in the direction of card displacement.

Claims

1. A friction connector for a smart card including a frame and at least one flexible blade attached to the frame and including a convex contactor, an electrical contact area which is prepared to rest in a flat conductive shield of the smart card, the contact area experiences the wear of the contactor in a given environment of use, a displacement with respect to its initial position, characterized in that the contactor is assembled so that the initial position of its contact area is changed with respect to the center of the protector in a direction opposite to the direction of said displacement.

2. The friction connector of claim 1, the flexible blade which is attached to the frame by a first end and includes the contactor at its second end, characterized in that the position of the contact area is located in the vicinity of the edge of the protector which is more distant than the first end of the blade.

3. The friction connector of claim 1 or 2 including at least two flexible blades attached to opposite sides of the frame, characterized in that the distance between the initial positions of the contact areas is less than the distance between the centers of the shields conductive

4. The friction connector of claim 1 or 2, includes at least two flexible blades joined on both sides of the frame, characterized in that the distance between the initial positions of the contact areas is greater than the distance between the centers of the frames. conductive protectors.

5. A reader of the smart card characterized in that it is provided with the connector of any of claims 1 to 4. The reader of the smart card of claim 5, characterized in that it includes the means to have the contactors of the connector of the closest conductive shields, to make them contact when the card is near the push position and in the push position. 7. A method for manufacturing a friction connector that includes the steps of: determining the direction of displacement that the electrical contact area of the connector contactor will withstand during wear in a given environment of use with respect to an initial position on the contact , and assembling the contactor so that the initial position of its contact area is changed in a direction opposite to the direction of said displacement of the electrical contact area.