Antenna arrangement for a chip card

An antenna arrangement for a chip card includes an antenna conductor structure that is formed from a surface conductor. The antenna conductor structure includes a dipole arrangement arranged on a card substrate and that has a first antenna strand and a second antenna strand. The antenna conductor structure includes a terminal arrangement connecting the antenna conductor structure to a chip and for forming a transponder including the antenna conductor structure and the chip. A surface of the card substrate is divided into a grasping zone for handling the chip card and a transponder zone for arranging the transponder in such a manner that the grasping zone extends beyond a center region of the substrate surface and at least one lateral edge of the grasping zone is formed by a lateral edge of the substrate surface.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to PCT International Application No. PCT/DE2009/003070 filed on Apr. 28, 2009, which claims priority to German Patent Application No. 10 2008 024 790.1 filed May 23, 2008, both of which are incorporated herein by reference.

Not applicable.

FIELD OF THE INVENTION

The present invention relates to an antenna arrangement for a chip card, comprising an antenna conductor structure that is formed from a surface conductor, wherein the antenna conductor structure comprises a dipole arrangement that is arranged on a card substrate and that has a first antenna strand and a second antenna strand, and the antenna conductor structure comprises a terminal arrangement for connecting the antenna conductor structure to a chip and for forming a transponder comprising the antenna conductor structure and the chip, wherein a surface of the card substrate is divided into a grasping zone for handling the chip card and a transponder zone for arranging the transponder in such a manner that the grasping zone extends beyond a center region of the substrate surface and at least one lateral edge of the grasping zone is formed by a lateral edge of the substrate surface.

BACKGROUND OF THE INVENTION

Antenna arrangements of the above-cited type are utilized in transponders which are operated in the UHF frequency range. In such UHF transponders, the antennas are frequently configured as a dipole antenna having a chip being disposed in the center of the antenna conductor structure and being contacted with the antenna conductor structure via a terminal arrangement.

Such UHF transponders are frequently designed as so-called “tags” which are planarly connected to the surface of the product to be labeled. In this context, for the positioning of tags, such application locations can be formed for the positioning of the tags which are not subjected to the direct manipulation by the person handling the product, i.e. for instance the staff member in wholesale or retail trade reading the transponder data with the aid of a mobile reading device, or the checkout staff reading the transponder data with the aid of a reading device for the purpose of billing. Consequently, the configuration of the transponders in the form of tags in the communication between transponder and reading device in practice scarcely causes any problems.

The situation changes if transponders being equipped with a dipole antenna are disposed in the handling zone and thus complete or partial covering of the dipole antenna by a finger of the person handling the transponder may lead to a detuning of the transponder frequency, and thus may cause a functional disruption in the communication between the transponder and the reading device.

This problem is encountered in particular if transponders being equipped with a dipole antenna are arranged in a chip card, wherein due to the small dimensions of the chip card alone, there is an increased risk that the dipole antenna is at least partially covered during the handling of the card. In a chip card, the central arrangement of the transponder conventionally known from the tags firstly would result in that the chip, and here in particular the mechanically sensitive connecting region of the chip to the dipole antenna, would be arranged in the center of the bending stresses acting on the chip card.

Moreover, the small dimensions of a chip card alone result in that the chip card is regularly held so as to be clamped between the thumb and the index finger and/or the middle finger of the person handling the chip card when the chip card is grasped, in particular in such a manner that the thumb and the finger are allowed to come into abutment essentially in the center region of the chip card surface. When a UHF transponder of the above-cited type is disposed in the central arrangement known from a tag, there is a high risk that at least a partial region of the dipole antenna is covered by the thumb and at least one finger, causing the thus involved detrimental consequences for the communication between the transponder and the reading device.

SUMMARY OF THE INVENTION

Hence, it is an object of the present invention to suggest an antenna arrangement having a dipole antenna for a chip card, wherein the risk of detuning of the transponder is significantly reduced.

In the inventive arrangement, the dipole arrangement of the antenna conductor structure is arranged in a portion of the substrate surface of the card substrate being referred to as “transponder zone” and which is situated remote from a substrate surface being referred to as “grasping zone”, so that the risk of parts of the dipole arrangement of the antenna conductor structure being covered when the chip card is grasped is significantly minimized. The aspect that the grasping zone starting from a lateral edge of the substrate extends beyond the center region of the substrate surface allows for grasping the card in a normal manner from at least one lateral edge of the chip card, i.e. by positioning the thumb and at least one finger in the center region of the card, without giving rise to the inevitable consequence that the antenna is detuned.

It proves to be particularly advantageous if a corner region of the grasping zone coincides with a corner region of the substrate surface, since in this way, the card can be grasped not only from at least one lateral edge of the chip card without the risk of a detuning of the antenna, but the card can also be grasped from the side without the risk of such a detuning.

According to another advantageous embodiment, a lateral edge of the grasping zone is defined by a lateral edge of the substrate surface in such a manner that two corner regions of the grasping zone and the substrate surface coincide, which corner regions are connected to one another via the lateral edge of the grasping zone. Such a configuration makes it possible to grasp the card both from a lateral edge and from two adjacent corner regions of the lateral edge without incurring the risk of detuning.

Moreover, the risk of antenna detuning can also be reduced by designing the antenna strands at their free ends as open conductor frames, so that for instance also in the case of an equi-long configuration of the antenna strands, by means of realizing a varying design, respectively size, of the free ends of the antenna strands being configured as open conductor frames, a variable frequency tuning can be performed which is respectively assigned to the antenna strands.

By designing the free antenna ends as conductor frames, it is also possible to design the antenna strands with relatively short dimensions, so that by means of this measure, the risk of covering the antenna strands by grasping the chip card can be further minimized.

If, according to a particularly preferred embodiment, the terminal arrangement for connecting the antenna conductor structure to the chip is designed as a loop dipole having a coupling conductor section being disposed in parallel to a coupling conductor section of the antenna conductor structure, which connects the antenna strands of the antenna conductor structure with one another, it is possible to dispose the terminal arrangement, respectively the chip contacted with the terminal arrangement, laterally with respect to the antenna strands of the antenna conductor structure, resulting in that the antenna strands can be laid even more closer to the lateral edge of the substrate surface.

In this context, it proves to be particularly advantageous if the coupling conductor section of the terminal arrangement and the coupling conductor section of the antenna conductor structure are arranged at a corner region of the substrate surface, since in this way, for forming the antenna strands, substantially the entire length of a transverse side and a longitudinal side of a chip card blank, respectively of the substrate surface, is available.

If, in this connection, the coupling conductor sections each feature two coupling arms being disposed at an angle to one another and extending in parallel to a lateral edge of the substrate surface, a positioning of the antenna arrangement is realized, wherein both the antenna strands and the terminal arrangement are disposed at the largest possible distance from the center region of the substrate surface.

If the terminal arrangement has at least two planarly formed terminal contacts which extend over substrate recesses being open towards a substrate rear side, it is possible to position the chip at the smallest possible distance from the neutral bending plane of the card substrate, and thus to shift the actual contacting region between the terminal contacts of the terminal arrangement and the chip contacts virtually into the neutral plane, i.e. into an inner region of the card substrate remaining essentially unstressed upon exposure to bending stresses. Hence, the mechanical bending stresses both occurring in the connecting region and acting on the chip can be minimized.

If the terminal contacts are applied to the card substrate integrally with the coupling conductor section of the terminal arrangement in the form of a material coating using a coating process, the need for forming fragile connecting points between the terminal contacts and the coupling conductor section can also be dispensed with.

It generally proves to be advantageous if the antenna conductor structure and the terminal arrangement formed therein are formed of a congruent material coating, since thus the entire antenna conductor structure can be produced in a single coating process.

If the terminal arrangement is formed of aluminum or an alloy containing aluminum, in particular in the instance where the chip being provided for the contacting with the terminal arrangement also features terminal contacts made of aluminum or an alloy containing aluminum, a direct contacting of the chip terminal faces with the terminal contacts of the terminal arrangement can be carried out using an ultrasonic welding process.

If the terminal arrangement is formed of copper or an alloy containing copper, a contacting with a chip by means of a conventionally utilized thermal bonding method can be realized.

According to another advantageous embodiment, the terminal arrangement can be formed on a chip carrier being designed separately from the card substrate, so that a contacting with the chip can be performed independently of the card substrate.

In this case too, the terminal arrangement can be formed from a material coating applied to the chip carrier using a coating process.

In particular it proves to be advantageous to form the dipole arrangement disposed on the card substrate from at least one wire conductor, in order to produce the dipole arrangement for instance by laying the wire conductor on the surface of the card substrate.

According to the invention, the transponder arrangement is equipped with an antenna arrangement being disposed on a card substrate, wherein the card substrate on its rear side is provided with a chip module, comprising a chip being arranged on a chip carrier in such a manner that, for electrically connecting the chip with the terminal arrangement of the antenna conductor structure, the chip carrier is contacted with the terminal contacts of the terminal arrangement via chip carrier contacts extending into the substrate recesses.

The inventive transponder arrangement thus not only enables a positioning of the antenna arrangement in a region which is most likely to remain uncovered by the thumb and the fingers when the chip card is grasped, but also enables an arrangement of the chip and the connecting region formed between the terminal arrangement of the antenna conductor structure and the chip carrier contacts directly adjacent to, respectively in the neutral plane of, the card substrate.

If, according to an advantageous embodiment, the chip carrier contacts and the terminal contacts are formed of aluminum or an alloy containing aluminum, a direct contacting of the contacts is enabled by exposure to ultrasound.

Arranging the chip on the same surface of the chip carrier as the chip carrier contacts makes it possible to arrange the chip directly adjacent to the substrate surface.

If, in addition, the chip is arranged so as to engage into a substrate recess formed in the card substrate for accommodating the chip, it is possible to arrange the chip as such in the neutral plane of the card substrate.

If, in addition, the substrate recesses for the engagement of the chip carrier contacts and the substrate recess for accommodating the chip are disposed to as to be essentially flush with respect to one another, a particularly small configuration of the chip carrier is realizable, so that the chip carrier along with the chip can be disposed as close as possible to the lateral edge of the card substrate.

According to the invention, the card substrate on its surface is equipped with a chip carrier in such a manner that the coupling section of the terminal arrangement is disposed in a coupling section so as to be defined with respect to the coupling section of the dipole arrangement. The defined arrangement can be performed by an electrically conductive contacting or for instance also by a defined spacing-apart of the coupling sections for performing a contactless coupling.

In particular the defined spacing-apart can be performed in a laminate structure between the card substrate and the chip carrier.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

FIG. 1shows a card substrate10having the form and the dimensions of a chip card. In the chip card, which is not illustrated here in detail, the card substrate10illustrated inFIG. 1forms a layer of the chip card which is typically produced as a laminate structure, wherein the layer formed by the card substrate10is arranged between outer cover layers, which are not illustrated here in detail.

The card substrate10illustrated inFIG. 1has a substrate surface11which is divided into a grasping zone12and a transponder zone13. Here, the grasping zone12designates the region in which at least partial covering of the substrate surface11on a frontal side14by a thumb and on a rear side15by one or more fingers of the same hand is caused when a card user grasps the card substrate10, respectively the chip card, as is indicated inFIG. 1.

In the card substrate illustrated inFIG. 1, the transponder zone13is essentially designed with an L-shape and accommodates an antenna conductor structure16, which has two antenna strands18and19forming a dipole arrangement17and being integrally connected to one another via a coupling conductor section20. The antenna strands18,19at their free ends each have open conductor loops, respectively conductor frames21,22, which in the case at hand are designed with different sizes.

The dipole arrangement17of the antenna conductor structure16in the exemplary embodiment illustrated inFIG. 1with the here comparatively longer designed antenna strand18extends longitudinally along a longitudinal lateral edge23of the card substrate10, and the comparatively shorter designed antenna strand19extends longitudinally along a transverse lateral edge24of the card substrate10in such a manner that the coupling conductor section20connecting the antenna strands18,19is disposed adjacent to the longitudinal lateral edge23and the transverse lateral edge24in a corner region25of the card substrate. In the corner region25, a terminal arrangement26of the antenna conductor structure16is also disposed, which in the case at hand is designed as a loop dipole having an essentially U-shaped conductor arrangement27, which at its free ends is equipped with planarly formed terminal contacts28and29. The terminal contacts28and29serve for contacting with a chip, which is not illustrated inFIG. 1.

The entire antenna conductor structure16, comprising the dipole arrangement17and the terminal arrangement26, is formed from a metallic coating, for instance containing aluminum or copper, being applied to the substrate surface11of the card substrate10. Said coating can be applied in coating processes known from the state of the art, i.e. for instance in an etching process or a printing process. The material used for the card substrate in particular may be a plastic material, such as PVC, PETG, polycarbonate or the like.

Irrespective of the material selected for the coating and the application method for applying the coating on the substrate surface11, in the exemplary embodiment of the antenna conductor structure16illustrated inFIG. 1, the terminal arrangement26and the dipole arrangement17interact in such a manner that an electromagnetic coupling is created between the terminal arrangement26and the dipole arrangement17in the region of the coupling conductor section20of the dipole arrangement17and a coupling conductor section81of the terminal arrangement26. By means of this aspect, it is possible to carry out a transmission of receiving or transmitting frequencies between the dipole arrangement17of the antenna conductor structure16and a chip which is contacted with the terminal contacts28,29of the terminal arrangement26and which is not illustrated here in greater detail, essentially unaffected by disruptive contact points, as a result of the electromagnetic and thus contactless coupling.

As is apparent from the illustration according toFIG. 1, the formation of the grasping zone12with a corner region30of the grasping zone12coinciding with a corner region31of the substrate surface11, and with lateral edges32,33of the grasping zone12which are formed by lateral edges34,35of the substrate surface11, enables large variability in the access to the card substrate10without causing a covering of portions of the dipole arrangement17by the thumb or the fingers of the grasping hand. Thus, starting from the positioning of the hand exemplarily illustrated inFIG. 1, swiveling of the hand by +/−45° with respect to a card diagonal line36can be readily performed without causing such covering.

FIG. 2shows a card substrate37having a grasping zone38and a transponder zone39, wherein the grasping zone38extends over two adjacent corner regions40and41and has three lateral edges42,43,44which are formed by lateral edges45,36,47of the substrate surface11.

Here, the transponder zone39being designed as a strip extends longitudinally along a further lateral edge48of the substrate surface11and accommodates an antenna conductor structure49which has a dipole arrangement50extending in a rectilinear fashion longitudinally along the lateral edge48.

As is apparent from a comparison ofFIGS. 1 and 2, the embodiment of the card substrate37illustrated inFIG. 2enables variability of the grasping position with respect to the card diagonal line26between −45° and +135°.

FIG. 3in another embodiment shows a card substrate51having a grasping zone52and a transponder zone53which is essentially designed in a U-shape and which extends over two adjacent corner regions54,55of the substrate surface11and extends longitudinally along lateral edges56,57and58being assigned to said edge regions. The grasping zone thus only features one lateral edge59which is freely accessible from the outside of the card substrate51and which is formed by a lateral edge60of the substrate surface11. However, said grasping zone just like the grasping zones12and38in the embodiments of the card substrate10and37illustrated inFIGS. 1 and 2, extends in the card depth beyond the center region61.

A comparison of the card substrate51illustrated inFIG. 3with the card substrates10and37illustrated inFIGS. 1 and 2reveals that the grasping zone52also enables variability in the access to the card substrate51still in the range of essentially +/−30° with respect to a center axis62of the card substrate51.

FIGS. 4 and 5show a longitudinal cross-section of the card substrate10illustrated inFIG. 1, whereinFIG. 4illustrates the card substrate10having the antenna conductor structure16formed thereon, and the illustration according toFIG. 5shows the antenna conductor structure16being contacted with a chip module63for the formation of a transponder module64.

From a combined view ofFIGS. 4 and 5it is rendered apparent that the chip module63for contacting with the terminal contacts28,29of the terminal arrangement26engages into substrate recesses67,68via raised chip carrier contacts65,66, and from the rear side15of the card substrate10is connected to a contact rear side69of the terminal contacts28,29. The chip carrier contacts65,66are each connected to a first and a second terminal conductor70,71which are here also arranged on a substrate72, here formed as a foil, of a strip-shaped chip carrier73in the form of a conductive metal coating comparable to the antenna conductor structure16. The ends of the terminal conductor70,71facing one another are contacted with chip contacts74,75of a chip76which is positioned on the same side of the chip carrier73as the chip carrier contacts65and66and which engages into a substrate recess77formed in the card substrate10as a chip accommodation.

As is evident from the illustration according toFIG. 5, the protruding contacting, respectively arrangement, of the chip76with the terminal arrangement26of the antenna conductor structure16enables a positioning of contact points78,79formed between the chip carrier contacts65,66and the terminal contacts28,29of the terminal arrangement26as well as of the chip76in the region of a neutral bending plane80, wherein tensions occurring upon exposure of the card substrate10to bending stresses are minimal.

FIG. 6shows a transponder arrangement82having a card substrate83, which on its surface has a dipole arrangement85formed from a wire conductor84. On the surface of the card substrate83, a chip carrier or a chip substrate86are also arranged, on which a chip88contacted with a terminal arrangement87is arranged as well. The terminal arrangement87has a coupling section89which is oriented in parallel to a coupling section90of the dipole arrangement85being disposed on the card substrate83and is oriented at a defined distance a and thus enables coupling between the loop dipole formed by the terminal arrangement87and the dipole arrangement85.

For setting the distance a, where required, the chip carrier86may be applied to the card substrate83provided with the dipole arrangement85or the dipole arrangement85may be applied to the card substrate83provided with the chip carrier86beforehand.