Radio frequency transmission and reception device comprising a conductive wire forming an antenna wound in turns

Abstract

The invention relates to a radio frequency transmit-receive 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). Figure 1

Description

Title of the invention: Radio frequency transmission and reception device comprising a conductive wire forming an antenna wound in turns. FIELD OF THE INVENTION

[0001] The present invention relates to a radio frequency transmit / receive device, such as an RFID tag (or "RFID tag" in English terminology). More particularly, the present invention relates to a flexible and robust radio frequency transmit / receive device. Such a device finds application in the field of object labeling, and particularly in the labeling of objects that are susceptible to deformation, as is the case, for example, in the field of textiles or for objects made of a deformable material, such as rubber-based objects. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] Document WO2019 / 175509 proposes a radio frequency transmit-receive device comprising an electronic circuit (for example, a transponder) consisting of a transmit-receive 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, braided, around a core film. This creates a transmit-receive device with a wire form factor that can be easily integrated into a wide variety of objects for their identification, tracking, management, or environmental monitoring.

[0003] The radio frequency transmission-reception device proposed in this document has a wire form factor and is deformable (i.e., it conforms to tensile, bending, and / or torsional stresses), which provides highly advantageous characteristics for its integration into certain products, such as textiles or rubber-based products. Due to the helical winding of the antenna around 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 breakage of this wire or detachment from its connection to the chip. This is particularly true when the core wire is chosen to be extensible, exhibiting a much greater elongation capacity than the metal wire forming the antenna. OBJECT OF THE INVENTION

[0004] One object of the invention is to provide a radio frequency transmission-reception device that differs from the prior art. This transmission-reception device may be more compact than a prior art device. It may also be flexible. BRIEF DESCRIPTION OF THE INVENTION

[0005] With a view to achieving one of these goals, the object of the invention proposes a radio frequency 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 features of the invention, taken alone or in any technically feasible combination: • the ribbon is arranged folded or wound on itself in the non-contiguous turns of the conducting wire; • the tape is laid flat in the non-contiguous turns of the conductor wire; • the ribbon has a width between 2 mm and 10 mm; • the radio frequency transmission-reception device has a length between 5 and 10 cm; • the ribbon is made of natural or synthetic fibers and / or plastic material and / or natural or synthetic rubber; • the ribbon has an elastic elongation capacity between 1% and 25%. • the conducting wire is made up of at least one metallic strand; • the conducting wire is made of a textile thread and at least one ribbon electrically conductive, the electrically conductive ribbon being wound in coils around the textile thread; • the conductive wire and the electronic chip are incorporated into a protective braided wire or at least partially coated with a protective material; • the radio frequency transmission and reception device further includes at least one cover wire, which is not electrically conductive, extending longitudinally in turns around the ribbon; • the radio frequency transmission-reception device has cauterized ends; • the non-contiguous turns have a density between 300 revolutions / m and 500 revolutions / m. Brief description of the drawings

[0007] Other features and advantages of the invention will become apparent from the detailed description of the invention which follows with reference to the accompanying figures in which:

[0008] [Fig.1]

[0009] Fig. 1 represents a radio frequency transmission-reception device according to the invention;

[0010] [Fig.2a]

[0011] [Fig.2b]

[0012] [Fig.2c]

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

[0014] [Fig.3]

[0015] Fig. 3 represents a chain of electronic chips;

[0016] [Fig.4]

[0017] Figure 4 illustrates an example of interconnecting a chip to a conductive wire in a chain of electronic chips. DETAILED DESCRIPTION OF THE INVENTION

[0018] Figure 1 represents an embodiment of the radio frequency transmission-reception device 1 which is the subject of this description. This device 1 comprises, in a very general way, 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 provides support for the winding of the conductor wire 3, giving the device 1 its shape and properties, particularly its flexibility. Winding this wire 3 onto a ribbon 4 with a relatively large width, compared to a simple core wire in the prior art, makes it possible to form a more compact device (i.e., one of shorter relative length) for a given length of conductor wire 3. The device's increased width facilitates its handling and integration into certain objects.

[0020] The term "ribbon" should be interpreted here according to its conventional definition, as a narrow, long strip of flexible material. Thus, the ribbon 4 of a device according to the invention may have a width, measured when the ribbon is laid 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 makes up this ribbon can be of any kind, provided that it is not electrically conductive, so as not to impair the operation of the antenna formed by 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 can be a textile sheet, formed of textile threads extending parallel to each other without necessarily being held together.

[0021] Device 1 may have the particularity of being flexible, notably thanks to the presence of the ribbon. For the purposes of this application, "flexible" means that device 1 (and the ribbon 4 itself) is capable of flexing, preferably over a large amplitude, under its own weight, without having any resistance.

[0022] It is not necessary for the ribbon 4 to be held flat in the winding of the conductor wire 3, as schematically illustrated in [Fig.2a], although this configuration is particularly advantageous, as it makes the best use 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 ([Fig. 2b]), which doubles its thickness, or even wound upon itself ([Fig. 2c]), which tends to give it a wire-like form factor and make it slightly more rigid than in its flat form of [Fig. 1]. In all cases, it is held in place by the conductive wire 3, whether flat, folded, or wound. The following description will show how the shape of the ribbon can be chosen during the manufacture of the device 1 by wrapping the conductive wire 3 around the ribbon 4.

[0024] As can be seen in Figures 2a, 2b, and 2c, whether the tape is held flat, folded, or wound, the device 1 has a generally elliptical cross-section, thus having a width (in tape width) greater than its height (in tape thickness). When the tape is folded or wound, and its aspect ratio approaches that of a wire, its cross-section has a larger dimension than a simple core wire and forms a winding support with a lower density than a simple core wire. These characteristics allow the device to be made more compact, as previously stated, without introducing excessive rigidity.

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

[0026] As regards the conductive wire 3, it can take many forms. In particular, it can be made of a metallic wire, consisting of a single metallic strand or a plurality of metallic strands, for example in a twist, or of a metallic ribbon. By way of example, the conductive material constituting the conductive wire 3 can be copper or copper alloy (brass, bronze, cupro-nickel, silver-plated copper, etc.), steel, stainless steel, copper-plated steel, nickel, or metallized fibers such as silver-plated nylon. The wire or metallic ribbon can be coated with a thin conductive material, typically less than 2 µm, to improve electrical conductivity 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. Conductive wire 3 advantageously has a diameter (when formed from a wire) or a thickness (when formed from a ribbon) of less than 100 microns.

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

[0028] The conductive wire 3 forming the antenna of the transmitting-receiving device 1 has a length approximately equal to half the wavelength of the transmission frequency between the device 1 and a distant interrogator. For typical transmission frequencies, its linear length is therefore on the order of 4 to 20 cm.

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

[0030] The invention is by no means limited to the winding of a single conductive wire, and it can be foreseen 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 data processing or memory capabilities, or possess electroluminescent properties. In all cases, it has a transmit-receive capability and, when connected to the conductive wire 3 forming an antenna, is capable of sending or receiving information. It can be an identification electronic 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 an 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 radio frequency transmission-reception device 1 according to the invention includes 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 attached to this wire from the external environment, a protective wire can be provided, wrapped around this assembly. Alternatively, or in addition, the conductive wire 3, a portion of this wire, and / or the chip 2 can be coated with a protective material, such as a resin or, more generally, a polymer material.

[0034] Similarly, a non-electrically conductive cover wire 5 can be provided, extending longitudinally in turns around the ribbon 4. Advantageously, the winding direction of the cover wire 5 on the ribbon 4 is opposite to the winding direction of the conductive wire 3 on this ribbon 4. In this way, the torsional forces that these two wires apply to the ribbon are balanced.

[0035] In certain cases, a plurality of cover threads 5 can be used, three cover threads 5 in the example shown in [Fig. 1], advantageously balancing the torsional forces by mixing the winding directions. This multiple winding of cover threads 5 provides more complete protection for the active part of the device 1, the electronic chip 2 and antenna 3, by providing extra thickness in the fabric. This extra thickness can, in particular, create a "dead zone" on either side of the tape 3, allowing the device 1 to be sewn, for example, onto a label or into the overlock stitch of a textile product, without risking damage to the active part of the device 1. In addition to or instead of these cover threads, the device 1 can be coated with a protective resin or polymer.

[0036] In certain embodiments, the covering thread(s) and / or the coating resin may be chosen to be of a thermofusible nature, that is to say, to have a relatively low melting temperature, for example between 80°C and 120°C. The wide cross-section of the device 1 can then be used to attach it to an object by applying a sufficient temperature to the device 1 to melt the material. This temperature increase can be combined with compression of the device onto the object to maximize their contact surface area.

[0037] To preserve the integrity of device 1, and more particularly to prevent the conductor wire 3 and any cover wires 5 from unwinding from the tape 4, or from fraying, both ends of device 1 are cauterized, that is to say, at least some of the fibers or, more generally, the material that makes up the tape 4 and any cover wires are melted or sealed together to prevent this unwinding and / or fraying. Cauterization or sealing can be achieved by any suitable method, for example by locally raising the temperature of device 1 at its ends, thereby melting at least part of the material composing them. This can be achieved, in particular, by applying ultrasound, via a sonotrode, as is well known, or by laser. Alternatively, or in addition to this heat treatment, the ends of the device can be coated with a resin to seal the fibers and materials together and thus cauterize them.

[0038] The manufacture of a radio frequency transmission-reception device 1 according to the invention can be carried out simply, by collectively preparing a large number of such devices from a long ribbon and a chain of electronic chips 2 carried by a long conducting wire.

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

[0040] The present invention is not limited to a particular technology for preparing the chip chain 7, and any assembly method for providing such a chain 7 may be suitable. Preferably, however, the chip chain 7 is obtained by means of 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 which is shown in [Fig. 4], the chips 2 are provided with two longitudinal grooves. The grooves can respectively include connection pads 4a, 4b connected to inputs and / or outputs of a functional circuit 4 of the chip 2. The grooves are designed to house conductive wires, and in particular a portion of the long conductive wire 3', and thus to connect the chip 2 to this wire. When the conductive wires are correctly housed in the grooves, embedded or held in place by soldering, brazing, or 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 long conductive wire 2' to form an impedance matching loop for the chip 2.

[0042] The insertion of the long conductor wire 3' and the second conductor 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 US 11209799. After its manufacture, the chip string 7 can be wound onto a support, such as a reel.

[0043] The invention is by no means limited to the preparation of a chain of chips 7 by inserting conductive wires into grooves carried by these chips 2. One could, for example, employ a technology in which the long conductive wire 3' (or a plurality of such wires) is electrically connected to a connecting pad formed on the surface of the chip 2. The implementation of such an approach is described in particular in document WO2013114009 or US patent 11081466.

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

[0045] To obtain a radio frequency transmit-receive device 1 according to the invention, the chip chain 7 is wound on a long ribbon, for example by wrapping.

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

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

[0048] This ribbon runs through the reel while being held flat. This flat running can be facilitated by positioning the ribbon on cylindrical rollers, arranged upstream and downstream of the winding zone. It is understood that at this zone, the chip chain 7, which winds onto the long ribbon, applies a torsional force to this ribbon when it comes into contact with one of its sides. If the long ribbon has a greater rigidity than the conductor wire 3' of the chain 7, this wire 3' will deform to wind itself onto the long ribbon. without deforming it, and maintaining its "flat" position. If, on the other hand, the ribbon has less rigidity than the 3' warp thread, it will deform and fold back on itself, or even wrap itself around itself when its rigidity is very low. It is therefore clear that the rigidity of the long ribbon moving through the winding equipment dictates how the long ribbon is positioned within the winding of the warp thread: flat, folded back on itself, or wrapped around itself.

[0049] The rigidity of the ribbon can be perfectly controlled by selecting the tension at which it runs through the winding equipment, and in particular at the winding zone. This tension can be selected, for example, by controlling the spacing of the cylindrical rollers that guide the ribbon through the equipment, or by any other means of tension control. As an example, the ribbon can be run over a drawing mechanism, located upstream of the reel carrying the covering yarn, comprising a first drive shaft with a first rotational speed, and a second drawing shaft with a second rotational speed, higher than the first. By controlling the speed differential between the drive shaft and the drawing shaft, the tension of long ribbons can be controlled.

[0050] Thus, by choosing the tension to which the long ribbon is subjected during its movement, one can choose the shape, flat, folded or wound, of the long ribbon after the winding operation, and therefore of the ribbon 3 in the radio frequency transmit-receive device l. It should be noted that one can also promote the folding of the ribbon during this step by winding it on a guide piece, for example inside a U-shaped piece, before the winding area.

[0051] It is naturally possible, during this step of winding the chip chain 7, to wind the covering wire(s) simultaneously or successively, as previously described. It is also possible to precede this step with a preliminary winding step, during which at least one covering wire is wound in a spiral around the chip chain 7, this chain 7 then moving through the reels while the covering wire is being wound.

[0052] The winding technique is not the only technique that can be used to wind the chain of chips 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. The term "turn" should therefore be understood as any form of winding of the conductive wire 3 around the ribbon or any interlacing of these two elements.

[0053] To form radio frequency transmitting and receiving devices 1 from the winding recovered from the collection reel of the winding equipment, it suffices to extract segments, each segment comprising a chip 2 and having a sufficient number of turns to form a functional antenna. At this stage, the cauterization operation of the ends of the extracted device can be carried out, as previously described.

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

[0055] Thus, the radio frequency transmission and reception device described herein can be incorporated directly into a product, for example, a textile product such as clothing. However, this device may find applications in other areas besides textiles, and it could be advantageous for the electronic labeling of any type of product, particularly those with a degree of flexibility.

[0056] The device can be integrated directly, for example by sewing it directly into a piece of fabric or by incorporating it into an overlock stitch. However, it can also be integrated or pre-attached 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 elastomeric product) during its manufacture, and in particular before the cooking stage.

Claims

Demands

1. Radio frequency transmitting and receiving 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).

2. Radio frequency transmitting and receiving device (1) according to the preceding claim in which the ribbon (4) is arranged folded or wound upon itself in the non-contiguous turns of the conducting wire (3).

3. Radio frequency transmitting and receiving device (1) according to claim 1 in which the ribbon (4) is arranged flat in the non-contiguous turns of the conducting wire (3).

4. Radio frequency transmit-receive device (1) according to any one of the preceding claims wherein the ribbon (4) has a width between 2 mm and 10 mm.

5. Radio frequency transmitting and receiving device (1) according to any one of the preceding claims having a length between 5 and 10 cm.

6. Radio frequency transmit-receive device (1) according to any one of the preceding claims wherein the ribbon (4) is formed of natural or synthetic fibers and / or of a plastic material and / or of natural or synthetic rubber.

7. Radio frequency transmit-receive device (1) according to any one of the preceding claims wherein the ribbon (4) has an elastic elongation capacity of between 1% and 25%.

8. Radio frequency transmitting and receiving device (1) according to any one of the preceding claims wherein the conducting wire (3) is formed of at least one metallic strand.

9. Radio frequency transmitting and receiving device (1) according to any one of claims 1 to 7 in which the conducting wire (3) is formed of a textile yarn and at least one electrically conductive tape, the electrically conductive tape being wound in turns around the textile yarn to cover it at least in part.

10. Radio frequency transmitting and receiving device (1) according to any one of the preceding claims in which the conductive wire (3) and an electronic chip (2) are incorporated in a protective braided wire or at least partly coated with a protective material.

11. Radio frequency transmitting and receiving device (1) according to any one of the preceding claims further comprising at least one cover wire (5), electrically non-conductive, extending longitudinally in turns around the ribbon (4).

12. Radio frequency transmitting and receiving device (1) according to any one of the preceding claims having cauterized ends (6).

13. Radio frequency transmit-receive device (1) according to any one of the preceding claims wherein the non-contiguous turns have a density between 300 turns / m and 500 turns / m.

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