Contact Frame for an IC Card Reader

The present invention relates to IC card readers. The term "IC card" is used to designate any card including at least one electronic component with which electrical connections are to be established in a reader fitted to an apparatus which is operated by this type of card (e.g. a bank terminal or a pay phone).

In general, IC card readers comprise guide means for guiding or positioning the card, optional means for verifying that a card is present in the reader, and is present in an appropriate position, and also contact elements for providing electrical connection with conducting pads on the IC card via which circuits are established to the apparatus including the IC card reader.

One such IC card reader is described in French patent No. 2 534 713. The guide means therein are surfaces associated with the structure of the reader. The presence of a card is verified by means of an end-of-stroke microswitch and the contact elements are resilient metal blades mounted in a frame of insulating material.

There are thus three independent parts, and assembly thereof is not described in detail. Unfortunately, such a structure requires the various parts to be assembled accurately, and not only is this expensive, but given the accumulated assembly tolerances on the various parts, this may also lead to it being impossible, in practice, to satisfy the requirements of the user. In addition, the actual assembly is left to the manufacturer of the apparatus, whereas such a manufacturer would find it appreciably easier to use a unit component which did not require any special precautions.

More precisely, the force exerted by each of the contact elements for connection to the IC card when pressing against a conducting pad of a card can be expressed by an equation of the type f=kx, where k represents the resilient characteristics of the contact element, and x represents the deflection to which said contact element is subjected in the presence of a card. This force f must be obtained relatively accurately, i.e. with relatively narrow tolerances, since if it is too small then there are problems of contact resistance, and if it is too large, then there are problems of wear both with the contact elements and with the cards. Further, the force exerted by all of the contact elements together on a card give rise to a force retaining the card in the apparatus, and this overall force is also subject to narrow tolerances. Unfortunately, the value of k may vary in the course of industrial manufacture by as much as .+-.25%, for example. Although this amount of tolerated variation could be reduced to a smaller value, that would require expensive measures to be undertaken. If it is desired that the force f remain within limits which are not much wider than those allowed to the factor k, then x must be defined as narrowly as possible. In other words accurately positioning the card relative to the contact elements is of capital importance.

The object of the invention is thus to provide a unit component called herein a "contact frame", said component solving the problems of assembly tolerances and making it possible to satisfy the severest card positioning requirements at reduced cost, said component being very simple to use.

The present invention includes the improvement of comprising an inner frame carrying the contact elements for connecting with the IC card, with the substance of said inner frame being extended by two extensions extending towards the side edges of the card and beyond said edges, each of said two extensions carrying means for defining the position of a corresponding one of two card-guiding slideways.

These extensions are preferably perforated. At least a portion of the slideway is formed in the substance of each extension. At least a portion thereof may be added to each extension. An add-on piece constituting a lid may extend from one slideway to the other. A brake pressing the card against the add-on piece may be incorporated either in the contact frame or else in its lid. Finally, the frame may include an end-of-stroke abutment and an end-of-stroke contact whose components are inserted in the frame.

An embodiment of the invention is described by way of example with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a contact frame in accordance with the present invention;

FIG. 2 is a plan view of the FIG. 1 frame;

FIG. 3 is an end view of the FIG. 1 frame, with a lid constituting the card-guiding slideways;

FIG. 4 is a fragmentary end view showing slideways formed in part on the frame and in part on the lid; and

FIG. 5 is a side view of the FIG. 3 frame.

FIG. 1 is a perspective view of a contact frame 1 designed in accordance with the present invention and showing an IC card 2 in position to be inserted. For the purposes of this description, these two parts are shown upside down relative to the normal position thereof in which the card is presented with its contact zone on top and in which the contact frame 1 should therefore be disposed above the card and facing the card. The frame essentially comprises a part 3 made of molded insulating material and acting simultaneously: as a support for contact elements 4 used for making connections with the integrated circuit (IC) on the card 2; as a support for an end-of-stroke contact 5 for indicating that a card is present in the reader and properly positioned for the purposes of being read; and as a support at least for slideways 6 for guiding the card and intended to lead it to the above-mentioned position in which it can be read.

To this end, the contact frame 1 comprises an integral inner frame portion 7 constituted by portions of the frame 1 delimiting connection windows 8, 9, 10, and 11. The contact elements 4 extend into these windows from bars 13 and 12 in which they are overmolded. It can thus be understood that the positions of the contact elements 4 are determined by the positions of a portion of the mold used for forming the frame 1. The contact elements 4 are shaped and they project above the plane 14 of the top surface of the frame 1. They are intended to come into contact with contact pads in the connection zone 15 of the card 2 when the card is properly inserted in the IC card reader. With reference to FIG. 2 which is a plan view of the FIG. 1 contact frame, it can be seen that the windows 8 to 11 include indentations 16 which protect the ends of the contact elements 4.

The inner frame portion 7, as shown in FIGS. 1 and 2, is extended by two extensions 17 and 18 which terminate at their ends furthest from the inner frame portion 7 in sildeway supports 6. In a first embodiment, these supports 6 are mere flat surfaces, each provided with at least one centering peg 19 or 20. Other slideway positioning means could be provided instead of or in addition to those mentioned above. Further, the centering pegs such as those shown in FIGS. 1 and 2 may also serve as fixing means (e.g. by rivets) for the slideways. Reference is made to FIG. 3 which is an end view of the frame 1 as shown in FIGS. 1 and 2, shown the usual way up, this time. It can be seen that slideways 21 and 22 are both formed in a piece of molded insulating material constituting a lid 23 and mounted on the support 6 of the frame 1. The lid 23 is accurately positioned relative to the frame 1 by the centering pegs 19 and 20. It guides the card 2 by engaging its edges. If the same portion of the mold as that which defines the positons of the contact elements 4 also serves for defining the surfaces 6 and the centering pegs 19 and 20, then the positioning of the card 2 relative to the contact elements 4 is obtained with a degree of accuracy which is now related solely to the care with which the mold for forming the frame 1 is made and to the assembly tolerances between the frame 1 and the lid 23, which assembly is performed in the factory, i.e. with narrow tolerances.

As can be seen in FIGS. 1 and 2, the extensions 18 and 19 are perforated with relatively large holes 24 in order to save plastic.

The contact frame 1 also carries an end-of-stroke contact 5 and an end-of-stroke abutment 25. The end-of-stroke contact 5 is normally closed contact which is opened by the card shortly before it comes into abutment against the end-of-stroke abutment 25 by pressing against the end 27 of a moving blade 26, thereby separating the blade from a fixed contact 28. The two blades are force-fitted in slots 29 and 30 provided in the frame 1, thereby ensuring that they are accurately positioned. Further, the abutment 25 ensures that the card is properly positioned in the IC card reader.

Finally, FIGS. 1 and 2 show a pusher 31 which is integrally molded with the frame 1 and which comprises a resilient blade for pressing the IC card 2 against the lid 23, thereby pressing it against the face of the slideway opposite to the contact elements and thus accurately defining the distance of the card from the contact elements 4.

As can be seen in FIGS. 3, 4, and 5, the pusher may alternatively be integrally formed with the lid 23, extending from the end thereof which is not reached by the card, and being cantilevered back from that and towards the center of the frame 1. Its end 34 is shaped so as to be cammed away by the leading edge of the card 2, after which it exerts pressure on the card by means of a rounded surface so as to avoid damaging the card.

It may also be observed that the opening via which the IC card is inserted between the parts 1 and 23 is chamfered at 32 in conventional manner.

There remains the possibility, which can be seen by comparing FIGS. 3 and 4, that at least a portion of the slideway on either side of the frame is integrally formed with the frame 1, as shown in FIG. 4. This provides an IC card reader having all of its dimensional tolerances determined by a single molded part, thereby providing a solution which is both effective and cheap. However, the slideways may be at least partially formed in parts which are added on, or preferably in a single lid-forming add-on part, as shown in FIG. 3, for example. Insofar as this part may itself be mounted on the frame 1 during manufacture of the frame, narrow tolerances can still be ensured under economic conditions.

Naturally, the above description is given purely by way of non-limiting example and numerous variants may be envisaged without thereby going beyond the scope of the invention.