Radio frequency transceiver device comprising a conductive wire forming an antenna wound in turns

Abstract

The invention relates to a radio frequency transceiver device (1) comprising at least one conductive wire (3) that forms an antenna and is electrically connected to at least one electronic chip (2), the conductive wire (3) extending longitudinally in non-contiguous turns around a ribbon (4).

Description

Radiofrequency transmitting-receiving device comprising a conductive wire forming an antenna wound in turns FIELD OF THE INVENTION

[0001] The present invention relates to a radiofrequency transmission and reception device, such as an RFID tag. More particularly, the present invention relates to a flexible and robust radiofrequency transmission and reception device. Such a device finds an application in the field of labeling objects, and more particularly objects likely to deform, as is the case, for example, in the textile field or for objects formed from a deformable material such as rubber-based objects. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] Document WO2019 / 175509 proposes a radiofrequency transceiver device comprising an electronic circuit (for example a transponder) formed of a transceiver chip, in particular an identification chip, and an antenna electrically connected to the chip. According to this document, the metal wire forming the antenna is wound in turns, covered, around a core film. This forms a transceiver device having a wire form factor which is easily integrated into a wide variety of objects, for their identification, their tracking, their administration or the monitoring of their environments.

[0003] The radiofrequency transceiver device proposed by this document has a wire form factor, a deformable character (i.e. it conforms to tensile, bending and / or torsional stresses) which forms very advantageous characteristics for its integration into certain products, such as textile or rubber-based products in particular. Due to the helical winding of the antenna on the core wire, the device can withstand significant longitudinal tensile forces, without putting tension on the metal wire forming the antenna and therefore without risking breaking this wire, or detaching its connection to the chip. This is particularly the case when the core wire is chosen to be extensible, having a much greater elongation power than the elongation power of the metal wire forming the antenna. SUBJECT OF THE INVENTION

[0004] An aim of the invention is to propose a radiofrequency transceiver device which is distinguished from the state of the art. This transceiver device may be more compact than a device of the state of the art. It may also be flexible. BRIEF DESCRIPTION OF THE INVENTION

[0005] With a view to achieving one of these aims, the subject of the invention proposes a radiofrequency transmission-reception device comprising at least one conductive wire forming an antenna and electrically connected to at least one electronic chip, the conductive wire extending longitudinally in non-contiguous turns around a ribbon.

[0006] According to other advantageous and non-limiting characteristics of the invention, taken alone or in any technically feasible combination: the ribbon is arranged folded or wound on itself in the non-joining turns of the conductive wire; the ribbon is arranged flat in the non-joining turns of the conductive wire; the ribbon has a width of between 2 mm and 10 mm; the radiofrequency transmission-reception device has a length of between 5 and 10 cm; the ribbon is formed of natural or synthetic fibers and / or a plastic material and / or natural or synthetic rubber; the ribbon has an elastic elongation power of between 1% and 25%.the conductive wire is formed of at least one metal strand;the conductive wire is formed of a textile wire and at least one electrically conductive ribbon, the electrically conductive ribbon being wound in turns around the textile wire;the conductive wire and the electronic chip are incorporated in a protective covered wire or at least partly coated with a protective material;the radiofrequency transceiver device further comprises at least one electrically non-conductive covering wire extending longitudinally in turns around the ribbon;the radiofrequency transceiver device has cauterized ends;the non-joining turns have a density of between 300 turns / m and 500 turns / m.

[0007] Other characteristics and advantages of the invention will emerge from the detailed description of the invention which follows with reference to the appended figures in which:

[0008]

[0009] The represents a radiofrequency transmission-reception device in accordance with the invention;

[0010]

[0011]

[0012]

[0013] Figures 2a, 2b, 2c illustrate, in section, three embodiments of a radiofrequency transmission-reception device according to the invention;

[0014]

[0015] It represents a chain of electronic chips;

[0016]

[0017] Illustrates an example of interconnecting a chip to a conductive wire in a chain of electronic chips. DETAILED DESCRIPTION OF THE INVENTION

[0018] The represents an embodiment of the radiofrequency transmission-reception device 1 which is the subject of the present description. This device 1 comprises, in a very general manner, a conductive wire 3 forming an antenna and electrically connected to an electronic chip 2. The conductive wire 3 extends longitudinally in non-contiguous turns around a ribbon 4.

[0019] The ribbon 4 forms a support for the winding of the conductive wire 3, it gives the device 1 its form factor and its properties, in particular flexibility. The winding of this wire 3 on a ribbon 4 having a relatively large width, in comparison with a simple core wire of the state of the art, makes it possible to form a more compact device (i.e. of smaller relative length), for a given length of conductive wire 3. Its extended width of the device facilitates its handling and its integration into certain objects.

[0020] The term "ribbon" must here be interpreted according to its conventional definition, as a strip of flexible, narrow and long material. Thus, the ribbon 4 of a device according to the invention may have a width, measured when the ribbon is deployed flat, of between 2 mm and 10 mm. Its length, which determines the length of the device 1, is typically between 5 and 10 cm. Its thickness is generally less than 1 mm. The flexible material that composes this ribbon may be of any nature insofar as it is not electrically conductive, so as not to alter the operation of the antenna consisting of the conductive wire 3. It may in particular be a polymer material such as those forming natural or synthetic fibers, a plastic material or a natural or synthetic rubbery material. It may be a textile sheet, formed of textile threads extending parallel to each other without necessarily being held together.

[0021] The device 1 may have the particularity of being flexible, in particular thanks to the presence of the ribbon. By "flexible", we mean in the context of this present application the fact that the device 1 (and the ribbon 4 itself) is able to flex, preferably with a large amplitude, under the effect of its own weight, without having any hold.

[0022] It is not necessary for the ribbon 4 to be held flat in the winding of the conductive wire 3, as is schematically illustrated in the, even if this configuration is particularly advantageous, because it takes full advantage of the entire width of the ribbon.

[0023] In certain embodiments of the invention, illustrated in Figures 2b and 2c, the ribbon 4 can be folded back on itself (), which doubles its thickness, or even wound on itself (), which tends to give it a wire form factor and make it a little more rigid than in its flat form. In all cases, it is held by the conductive wire 3, flat, folded or wound. We will see in the rest of this description how we can choose, during the manufacture of the device 1 by wrapping the conductive wire 3 on the ribbon 4, the shape taken by this ribbon.

[0024] As can be seen in Figures 2a, 2b, 2c, and whether the ribbon is held flat, folded or wound, the device 1 has a generally elliptical section, therefore having a width (in width of the ribbon) greater than its height (in the thickness of the ribbon). When the ribbon is folded or wound, and its form factor approaches a wire factor, its section has a larger dimension than a simple core wire and it forms a support for the winding of lower density than a simple core wire. These characteristics make it possible to make the device more compact, as stated previously, without providing excessive rigidity.

[0025] To enable this wrapping operation, it is preferable for the ribbon to have limited elastic properties, for example, for it to have an elastic elongation power of less than 25% of its resting length, and preferably between 1% and 25% of its resting length. However, it is not excluded to use a ribbon having an elastic elongation power greater than 25%, for example a suspender ribbon, in certain applications.

[0026] As regards the conductive wire 3, this can take multiple forms. It can in particular be formed from a metal wire, consisting of a metal strand or a plurality of metal strands, for example in a strand, or from a metal ribbon. For example, the conductive material constituting the conductive wire 3 can be made of copper or copper alloy (brass, bronze, cupro-nickel, silver-plated copper, etc.), steel, stainless steel, copper-plated steel, nickel, metallized fibers such as silver-plated nylon. The wire or the metal ribbon can be coated with a thin conductive material, typically less than 2 µm, to improve electrical conduction at the periphery by skin effect or to provide protection against chemical corrosion such as gold or silver. The conductive material can be coated with an insulating layer such as enamel to protect it chemically and mechanically.The conductive wire 3 advantageously has a diameter (when it is formed from a wire) or a thickness (when it is formed from a ribbon) of less than 100 microns.

[0027] Advantageously, for reasons of robustness of the device 1, the conductive wire 3 is made up of a textile wire and at least one ribbon formed of an electrically conductive material, the ribbon being wound in turns around the textile wire to cover it at least in part. Detailed information on this type of conductive wire can be found in the document EP4044364. The textile wire may in particular be made from aramid fibers or an aromatic polyester and have an elastic elongation power greater than or equal to 5%, 20%, 50%, or even 100% of its resting length. Alternatively, it may be slightly elastic and have an elongation power of less than 5%. The ribbon may be made of a laminated metal wire. It may be wound in contiguous or non-contiguous turns on the textile wire.

[0028] The conductive wire 3 forming the antenna of the transceiver device 1 has a length substantially equal to half a wavelength of the transmission frequency between the device 1 and a remote interrogator. For the usual transmission frequencies, its linear length is therefore of the order of 4 to 20 cm.

[0029] Advantageously, the non-contiguous turns of the conductive wire 3 are arranged longitudinally on the strip 4 with a density which may for example be between 300 turns / m and 500 turns / m. For a linear length of conductive wire 3 forming an antenna (this linear length may be imposed for electromagnetic reasons of transmission-reception) a greater density of the turns makes it possible to reduce the total length of the device 1 and therefore to contribute to its compactness.

[0030] The invention is in no way limited to the winding of a single conductive wire, and it can be provided that a device 1 according to the invention incorporates a plurality of such wires.

[0031] The electronic chip 2, for its part, is an integrated electronic component implementing one or more functions. An electronic chip can thus form a sensor, have a data processing or memory capacity, or have electroluminescent properties. In all cases, it has a transmission-reception capacity and is capable, when connected to the conductive wire 3 forming the antenna, of sending or receiving information. It can be an electronic identification chip, capable of holding an identifier and transmitting this identifier upon request from a remote interrogator. The electronic chip 2 connected to the conductive wire forming the antenna can implement any suitable communication protocol, in any frequency range, for example an RFID or NFC protocol.

[0032] It can naturally be foreseen that a radiofrequency transmission-reception device 1 in accordance with the invention comprises other elements than the ribbon 4, the conductive wire 3 and the electronic chip 2 which have just been described.

[0033] Thus, to protect the conductive wire 3 and the electronic chip 2 retained on this wire from the external environment, a protective wire may be provided, covered on this assembly. Alternatively, or in addition, it may be provided to coat the conductive wire 3, a part of this wire and / or the chip 2 with a protective material, such as a resin or, more generally, a polymer material.

[0034] In the same way, it is possible to provide a covering wire 5, electrically non-conductive, extending longitudinally in turns around the strip 4. Advantageously, the direction of winding of the covering wire 5 on the strip 4 is opposite to the direction of winding of the conductive wire 3 on this strip 4. In this way, the torsional forces that these two wires apply to the strip are balanced.

[0035] In some cases, a plurality of cover threads 5 may be placed, three cover threads 5 in the example shown in the, advantageously seeking to balance the torsional forces by mixing the winding directions. This multiple winding of cover threads 5 makes it possible to more completely protect the active part of the device 1, electronic chip 2 and antenna 3, by providing a textile excess thickness. This excess thickness may in particular make it possible to form a “dead” zone on either side of the ribbon 3, this zone being able to make it possible to sew the device 1, for example on a label or in the overlock of a textile product, without risking damage to the active part of this device 1. In addition to or as a replacement for these cover threads, it may be possible to coat the device 1 with a protective resin or polymer.

[0036] In some embodiments, the covering wire(s) and / or the coating resin may be chosen to be of a hot-melt nature, i.e. to have a relatively low melting temperature, for example between 80°C and 120°C. Advantage may then be taken of the extended width section of the device 1 to attach it to an object by applying sufficient temperature to the device 1 to melt the material. This increase in temperature may be combined with compression of the device onto the object to maximize their contact surface.

[0037] To preserve the integrity of the device 1, and more particularly to prevent the conductive wire 3 and any covering wires 5 from unwinding from the ribbon 4, or from fraying, the two ends of the device 1 are cauterized, that is to say that at least some of the fibers or, more generally, the material that composes the ribbon 4 and any covering wires are melted or sealed together to prevent this unwinding and / or fraying. Cauterization or sealing can be obtained by any suitable means, for example by locally raising the temperature of the device 1 at its ends and thus melting at least part of the material that composes them. This can in particular be obtained by applying ultrasound, by means of a sonotrode, as is well known, or by laser.It is also possible, instead of or in addition to this heat treatment, to coat the ends of the device with a resin to seal the fibers and materials together and thus cauterize them.

[0038] The manufacture of a radiofrequency transmission-reception device 1 in accordance with the invention can be carried out simply, by collectively preparing a large number of such devices from a very long ribbon and a chain of electronic chips 2 carried by a very long conductive wire.

[0039] The manufacture of a device 1 therefore firstly comprises the preparation of this chain of chips 7, shown for illustration purposes in the. This chain 7 is therefore formed of a plurality of electronic chips 2 electrically connected to, and supported by, at least one very long conductive wire 3'.

[0040] The present invention is not limited to a particular technology for the preparation of the chip chain 7 and any assembly method making it possible to provide such a chain 7 may be suitable. Preferably, however, the chip chain 7 is obtained via the E-Thread™ technology, a detailed description of which can be found in documents US8471713, US8093617, US8723312, US2015318409, US8782880, US8814054 or US2015230336.

[0041] According to this approach, an example of implementation of which is shown in the, the chips 2 are provided with two longitudinal grooves. The grooves may respectively comprise connection pads 4a, 4b connected to inputs and / or outputs of a functional circuit 4 of the chip 2. The grooves are provided to house conductive wires, and in particular a portion of the very long conductive wire 3' and thus assemble the chip 2 to this wire. When the conductive wires are correctly housed in the grooves, embedded or retained by welding, soldering or by an adhesive, they are brought into electrical contact with the connection pads 4a, 4b. In the example shown, a second conductive wire 3b is inserted into the second groove of the electronic chip 2 and in contact with the second connection pad 4b. This second conductive wire 3b is also connected to the very long conductive wire 2' to form an impedance matching loop for the chip 2.

[0042] The insertion of the long conductive wire 3' and the second conductive wire 3b into the longitudinal grooves of the electronic chips 2 can be automated, for example using insertion equipment such as that described in documents US8782880 or US11209799. After its manufacture, the chain of chips 7 can be wound on a support, such as a reel.

[0043] The invention is in no way limited to the preparation of a chain of chips 7 by inserting conductive wires into grooves carried by these chips 2. For example, a technology could be used according to which the very long conductive wire 3' (or a plurality of such wires) is electrically connected to a connection pad formed on the surface of the chip 2. The implementation of such an approach is described in particular in document WO2013114009 or patent US11081466.

[0044] It is possible to provide, at this stage, to coat a part of the chain, for example the electronic chips 2 and / or the impedance matching loops formed in part by the second conductive wires 3b, or the entire chain with a protective material, as mentioned previously. This chain 7 can also be covered with a protective wire.

[0045] To obtain a radiofrequency transmission-reception device 1 in accordance with the invention, the chip chain 7 is wound on a very long ribbon, for example by wrapping.

[0046] As a reminder, in the conventional wrapping technique, a core yarn is generally pulled through a rotating hollow spool, the spool carrying a so-called "cover" yarn. The core yarn passes through the hollow spool in a vertical direction, pulling it upwards or downwards. The cover yarn unwinds from the hollow spool to form a balloon that winds helically around the core, in turns, at a winding zone. It is common to wind a plurality of cover yarns around the core, for example by arranging a plurality of hollow spools one above the other and circulating the core through each of the spools rotated in the same direction or in opposite directions. The wrapped core yarn is collected on a collection spool.

[0047] In the context of the present description, this wrapping technique is used by running the long ribbon through a hollow reel, carrying the chain of chips 7, which unwinds to wind this chain 7 in turns around the long ribbon. The linear density of the turns on the long ribbon and their non-jointed nature can be controlled by adjusting the parameters of the wrapping equipment, in particular the running speed of the long ribbon.

[0048] This ribbon runs through the reel while being kept flat. This flat running can be facilitated by positioning the ribbon on cylindrical rollers, arranged upstream and downstream of the area of ​​the winding zone. It is understood that at this area, the chip chain 7 which is wound on the very long ribbon applies a torsional force to this ribbon when it comes to bear on one of its sides. If the very long ribbon has a greater rigidity than that of the conductive wire 3' of the chain 7, this wire 3' will deform to wind itself on the very long ribbon, without deforming it, and maintaining its "flat" arrangement. If, on the contrary, the ribbon has a lesser rigidity than that of the conductive wire 3' of the chain, it deforms to fold back on itself, or even to wind on itself when its rigidity is very low.It is therefore understood that the rigidity of the long ribbon which passes through the wrapping equipment dictates the way in which the long ribbon is positioned in the winding of the conductive wire: flat, folded back on itself or wound on itself.

[0049] The rigidity of the ribbon can be perfectly controlled by choosing the tension with which it runs through the wrapping equipment, and in particular at the winding zone. This tension can in particular be chosen, for example by controlling the spacing of the cylindrical rollers which guide the running of the ribbon through the equipment, or by any other means of tension control. For example, it is possible to make the ribbon run on a drawing mechanism, arranged upstream of the reel carrying the covering wire, comprising a first drive shaft having a first rotation speed, and a second drawing shaft, having a second rotation speed, higher than the first rotation speed. By controlling the speed differential existing between the drive shaft and the drawing shaft, it is possible to control the tension of the very long ribbon.

[0050] Thus, by choosing the tension to which the long ribbon is subjected during its unwinding, it is possible to choose the shape, flat, folded or wound, of the long ribbon after the wrapping operation, and therefore of the ribbon 3 in the radiofrequency transmission-reception device 1. It is noted that it is also possible to encourage the folding of the ribbon during this step by making it unwind on a guide part, for example inside a U-shaped part, before the winding zone.

[0051] It is naturally possible, during this step of wrapping the chain of chips 7, to simultaneously or successively wrap the covering wire(s), as explained previously. It is also possible to precede this step with a preliminary wrapping step, during which at least one covering wire is wound in a turn on the chain of chips 7, this chain 7 then running in the coils during the winding of the protective wire.

[0052] The wrapping technique is not the only technique that can be used to wind the chip chain 7 onto the long ribbon. A braiding or cabling technique can also be used to obtain the configuration in which the conductive wire 3 extends longitudinally in non-contiguous turns around the ribbon. By "turn", we must therefore understand any form of winding the conductive wire 3 around the ribbon or of interlacing these two elements.

[0053] To form radiofrequency transmitting-receiving devices 1 from the winding recovered from the collection coil of the wrapping equipment, it is sufficient to take segments from it, each segment comprising a chip 2 and having a sufficient number of turns to form a functional antenna. At this stage, the operation of cauterizing the ends of the removed device can be carried out, as presented previously.

[0054] Of course, the invention is not limited to the embodiments described and variant embodiments can be made without departing from the scope of the invention as defined by the claims.

[0055] Thus, the radiofrequency transmission and reception device which is the subject of the present description can be incorporated directly into a product, for example a textile product such as clothing. But this device can find other fields of application than that of textiles, and it could be advantageous for the electronic labeling of any type of product, in particular those presenting a certain flexibility.

[0056] The device can be integrated directly, for example by sewing it directly into a textile piece or integrating it into an overlock. But it can be integrated or coupled beforehand to a label to facilitate its integration into the product as described in document FR2002785.

[0057] The device can also be placed between two strips of raw rubber, with a view to its integration inside the structure of a tire (or any other elastomer product) during its manufacture, and in particular before the curing stage.

Claims

Radiofrequency transmission-reception device (1) comprising at least one conductive wire (3) forming an antenna and electrically connected to at least one electronic chip (2), the conductive wire (3) extending longitudinally in non-contiguous turns around a ribbon (4). Radiofrequency transmission-reception device (1) according to the preceding claim in which the ribbon (4) is arranged folded or wound on itself in the non-contiguous turns of the conductive wire (3). Radiofrequency transmission-reception device (1) according to claim 1 in which the ribbon (4) is arranged flat in the non-contiguous turns of the conductive wire (3). Radiofrequency transmission-reception device (1) according to one of the preceding claims in which the ribbon (4) has a width of between 2 mm and 10 mm. Radiofrequency transmission-reception device (1) according to one of the preceding claims having a length of between 5 and 10 cm. Radiofrequency transceiver device (1) according to one of the preceding claims, in which the ribbon (4) is formed from natural or synthetic fibers and / or a plastic material and / or natural or synthetic rubber. Radiofrequency transmission-reception device (1) according to one of the preceding claims in which the ribbon (4) has an elastic elongation power of between 1% and 25%. Radiofrequency transmission-reception device (1) according to one of the preceding claims in which the conductive wire (3) is formed from at least one metal strand. Radiofrequency transmission-reception device (1) according to one of claims 1 to 7 in which the conductive wire (3) is formed from a textile wire and at least one electrically conductive strip, the electrically conductive strip being wound in turns around the textile wire to cover it at least in part. Radiofrequency transceiver device (1) according to one of the preceding claims, in which the conductive wire (3) and the electronic chip (2) are incorporated in a protective covered wire or at least partly coated with a protective material. Radiofrequency transmission-reception device (1) according to one of the preceding claims further comprising at least one electrically non-conductive cover wire (5) extending longitudinally in turns around the ribbon (4). Radiofrequency transmission-reception device (1) according to one of the preceding claims having cauterized ends (6). Radiofrequency transmission-reception device (1) according to one of the preceding claims in which the non-contiguous turns have a density of between 300 turns / m and 500 turns / m.

Images