radio frequency transmission and reception device comprising a flexible support

Abstract

The invention relates to a radio frequency transmit-receive device (1) comprising a flexible support (2), and a radio frequency transmit-receive module (3) attached to the flexible support (2). The module comprises a first antenna (3b) electrically connected to at least one electronic transmit-receive chip (3a). A second antenna formed of an electrically conductive strand (4) is attached to the flexible support (2). It is capable of inductively coupling to the first antenna (3b), and comprises at least one textile yarn (4a) and at least one electrically conductive element (4b) wound helically in turns around the textile yarn (4a). Figure 1

Description

Title of the invention: Radio frequency transmission and reception device comprising a flexible support. FIELD OF THE INVENTION

[0001] The present invention relates to a radio frequency transmit / receive device, such as an RFID tag (or "RFID label"). 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 field of objects that are susceptible to deformation, as is the case, for example, in the textile industry or for objects made of a deformable material. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] Documents US2014291409, US2020117973A, US20240038043, and WO202237900 describe flexible RFID tags for clothing or laundry products. These tags consist of a backing on which an RFID module is mounted. This module consists of an RFID chip electrically connected to a first antenna, referred to as the "near-field" or "magnetic" antenna. A second antenna, referred to as the "far-field" or "electric" antenna, capable of inductively coupling to the first antenna of the RFID module, is assembled, woven, or sewn into the flexible backing, or more generally, attached to this backing.

[0003] As recalled in document FR3036823, this second antenna can be made of stainless steel or copper, typically a wire composed of a plurality of twisted strands of stainless steel or a single-strand copper wire, possibly mixed with polyester or natural fibers.

[0004] When this second antenna is made of a multi-strand stainless steel wire, it is particularly rigid and difficult to integrate into a textile substrate. It imparts a rigidity to the RFID tag that makes it unsuitable for integration into the very flexible or lightweight textile components of which clothing is made.

[0005] When this second antenna is made of a single-strand copper wire, the RFID tag becomes particularly fragile, especially with regard to the mechanical stresses experienced during the washing cycles of the textile items in which such a tag is integrated. Under the effect of these stresses, the single-strand wire forming the second antenna in the far field is liable to break, rendering the RFID tag non-functional. SUBJECT OF THE INVENTION

[0006] One object of the invention is to provide a radio frequency transmission and reception device that overcomes these limitations. More specifically, one object of the invention is to provide a radio frequency transmission and reception device that is flexible, that is to say, that can be folded and unfolded effortlessly, and that is robust. BRIEF DESCRIPTION OF THE INVENTION

[0007] To achieve one of these goals, the object of the invention proposes a radio frequency transmission-reception device comprising: • a flexible support; • a radio frequency transmit-receive module attached to the flexible support and comprising a first antenna electrically connected to at least one electronic transmit-receive chip; • a second antenna formed of an electrically conductive strand attached to the flexible support and capable of coupling inductively to the first antenna, the second antenna comprising at least one textile wire and at least one electrically conductive element wound helically in turns around the textile wire.

[0008] According to other advantageous and non-limiting features of the invention, taken alone or in any technically feasible combination: • the second antenna is sewn, woven or embroidered into the flexible support or glued to the flexible support (2); • the second antenna is fitted with a protective sheath; • the protective sheath is formed from a protective wire, wrapped around the electrically conductive strand; • the protective sheath is formed of a protective material surrounding the electrically conductive strand; • the textile yarn has a diameter between 50 micrometers and 100 micrometers; • the textile yarn (4a) is formed from synthetic fibers such as polyester or polyamide fibers; • the electrically conductive element is a conductive ribbon; • the conductive tape has a thickness of less than 10 micrometers, preferably less than 5 micrometers, more preferably less than 3.5 micrometers, or even less than 1.5 micrometers; • the electrically conductive element is made of a metal or a plurality of metals, such as a copper-silver alloy; • the electrically conductive element is covered with an electrically insulating coating, such as a varnish or enamel; • the radio frequency transmit-receive module is attached to one side of the flexible support, for example by means of an adhesive material; • The radio frequency transmit-receive module is coated with a protective material, such as a resin. Brief description of the drawings

[0009] 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:

[0010] [Fig.1]

[0011] Fig. 1 schematically illustrates a radio frequency transmission-reception device according to the invention;

[0012] [Fig.2]

[0013] Fig. 2 represents a second antenna of a radio frequency transmission-reception device according to the invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] With reference to [Fig.1], a radio frequency transmission-reception device 1 according to the invention comprises a flexible support 2 and a radio frequency transmission-reception module 3 attached to the flexible support 2.

[0015] The flexible support 2 of the example in [Fig. 1] is in the form of a strip, but this is by no means an important feature. It can be made of a plastic or textile material, woven or non-woven, for example cotton, nylon, polyester, an elastomer or any other synthetic or natural material.

[0016] The radio frequency transmit-receive module 3 (hereafter referred to simply as the "RF module") consists of a first antenna 3b electrically connected (i.e., by a galvanic connection) to at least one electronic chip 3a, at at least one contact pad of this electronic chip 3a. The chip 3a may, in particular, be a radio frequency identification (RFID) chip. The chip 3a may be arranged on a substrate on which conductive tracks are laid, with the chip's pads in contact with these tracks, to form the first antenna 3b. The assembly may be encapsulated in a protective material, such as a resin, or placed in a protective housing to form the RF module 3. This first antenna 3b forms a "near-field" or "magnetic" antenna, as mentioned in the introduction to this application.

[0017] The RF module 3 is attached to the flexible support 2, for example by means of an adhesive material. Alternatively to, or in addition to, this method of attachment, the flexible support may be provided with a pocket into which the RF module 3 can be inserted to hold it against the flexible support 2. It may be possible, particularly if the flexible support is strip-shaped and sufficiently wide, to fold the support. 2 on itself in order to incorporate the RF module between two layers of this flexible support 2. Alternatively to this folding, it is possible to laminate, sew or glue a complementary flexible support onto the flexible support 2 on which the RF module 3 has been placed. In all cases, the RF module is held to the flexible support 2, on one of its faces or integrated into its thickness.

[0018] Returning to the description of device 1 in [Fig.1], this also includes an electrically conductive strand 4 attached to the flexible support 2. This electrically conductive strand 4 forms a second antenna, called a "far field" or "electric" antenna, capable of coupling inductively to the first antenna.

[0019] The second antenna does not necessarily extend in a straight line on the flexible support 2; it can be integrated into this support in any suitable pattern, particularly to promote its inductive coupling to the first antenna 3b of the RF module, for example, a meandering pattern as shown in [Fig. 1]. Generally, this second antenna 4 and the RF module are positioned relatively close to each other in order to obtain effective inductive coupling between the first and second antennas. To this end, in the example shown in [Fig. 1], the RF module 3 has been positioned at the bottom of a loop in one of the meanders of the electrically conductive strand 4 forming the second antenna.

[0020] The electrically conductive strand 4 is attached to the flexible support 2, for example, sewn, woven, embroidered, or glued onto or into this flexible support 2. The operation of attaching this strand 4 to the flexible support 2 can be carried out on the flexible support after its manufacture, for example, by sewing, weaving, gluing, or embroidering a long strand onto a ribbon, forming the flexible support, the ribbon being unwound from a spool. The ribbon, fitted with the long electrically conductive strand, can then be used to form a plurality of devices 1, before being cut into individual devices. Alternatively, this operation can be carried out simultaneously with the manufacture of the flexible support itself, for example, by weaving or embroidering a long electrically conductive strand during the weaving operation of a ribbon from which a plurality of flexible supports 2 will be extracted.

[0021] As stated in the introduction to this application, the aim is to form a second robust antenna, i.e., one exhibiting high mechanical strength, and flexible, i.e., capable of absorbing tensile, torsional, and / or bending forces on the flexible support 2 without deteriorating, even when these forces are repeated many times in a cycle, for example, during repeated washing cycles. To this end, and according to an important feature of this description shown in [Fig. 2], the electrically conductive strand 4 comprises a textile yarn 4a and at least one electrically conductive element 4b wound helically in turns around the textile thread 4a. This electrically conductive element 4b can notably take the form of a conductive thread or a conductive ribbon, the latter possibility being represented in [Fig.2].

[0022] The term "ribbon" refers to an elongated, flexible, and flat film. This ribbon may, for example, be made of a laminated metal wire.

[0023] Whether in the form of a thread or a ribbon, the electrically conductive element is wound helically around the textile thread 4a, slightly tight against this thread 4a. It is not necessary to provide any adhesive material between the textile thread 4a and the electrically conductive element 4b.

[0024] The textile yarn 4a can be made of synthetic fibers, such as polyester or polyamide fibers, or of natural fibers. For example, the textile yarn can be made from aramid fibers, and thus form a multifilament meta-aramid yarn (for example known under the trade name Nomex™), a yarn made of short or long meta-aramid fibers, such as a polyamide-imide (for example known under the trade name Kermel™). Alternatively, it can be a PBO (poly(p-phenylene-2,6-benzobisoxazole) yarn, known by the trade name Zylon™. It can also be made from an aromatic polyester (for example, known by the trade name Vectran™). It can also be a yarn made from a polymer such as PEAK (polyaryletherketones), natural fibers, glass fibers, carbon fibers, PPS (polyphenylene sulfide) fibers, or steel fibers.It can be anticipated that, in addition to or as a replacement for these fibers, textile yarn 4a may comprise a conductive strand (or a plurality of conductive strands) with a diameter of less than 20 microns. Textile yarn 4a is advantageously an electrical insulator or weakly electrically conductive, without however excluding the possibility that this textile yarn 4a may be conductive.

[0025] The textile yarn 4a advantageously has a circular or elliptical cross-section. Its diameter (or major axis in the case of an elliptical cross-section) is advantageously between 50 microns and 150 microns, to prevent it from being too rigid.

[0026] The electrically conductive element 4b, conductive wire or conductive tape, may, for its part, be made of a metal or a plurality of metals, for example a metal alloy.

[0027] The electrically conductive element 4b may be made of or comprise copper, brass, bronze, cupro-nickel, a copper alloy comprising more than 96% by mass of copper, nickel, or a copper-silver alloy.

[0028] It can be foreseen that this electrically conductive element 4b consists of a main layer or core made of a first material, this main layer or core being covered with a conductive coating. Thus, the main layer or The main core may be made of steel coated with a material selected from the group consisting of the following materials: silver, gold, copper, tin, nickel, brass, zinc, and tin alloys. Alternatively, the main core may be made of a material selected from the group consisting of the following materials: stainless steel, a nickel alloy in which nickel alone represents at least 45% of the mass of the alloy, a titanium alloy in which titanium alone represents at least 70% of the mass of the alloy, or nickel.

[0029] Advantageously, the coating has a lower electrical resistivity than the material forming the main layer or core. It can be chosen for its anti-corrosion properties, for example, by being made of silver.

[0030] Alternatively, the coating may be electrically insulating. It may be a varnish or an enamel, allowing the electrically conductive strand 4 to be protected from its environment, particularly during washing.

[0031] The coating, whether electrically conductive or insulating, can be formed by deposition on the main layer or core.

[0032] When the electrically conductive element 4b takes the form of a ribbon, it can be made from a rolled conductive wire. In this case, and advantageously, this rolling is carried out cold. Preferably, it is not followed by thermal annealing. This process increases the work hardening of the material and therefore its fatigue resistance.

[0033] Regardless of the chosen nature of the electrically conductive element 4b, and in order to preserve the flexibility of the textile yarn 4a composing the electrically conductive strand 4 and to allow it to be wound into turns around this textile yarn, the electrically conductive element 4b has a small thickness (in the case of a conductive ribbon) or a small diameter (in the case of a conductive yarn), between 1 micrometer and 10 micrometers. Preferably, this thickness is less than 5 micrometers, more preferably less than 3.5 micrometers, or even less than 1.5 micrometers. The electrically conductive element 4b is therefore capable of elastic or plastic deformation.

[0034] When it is in the form of a conductive ribbon 4b, the electrically conductive element 4b can have a width between 40 microns and 200 microns, without this characteristic forming any limitation.

[0035] The helical winding of the electrically conductive element 4b into turns around the textile film 4a can be carried out in several ways. The turns can be non-contiguous, that is, two successive turns are spaced apart and do not touch. Alternatively, the winding can be in contiguous turns or overlapping turns (in the case of a ribbon). Contiguous turns help to improve the electrical conductivity of the electrically conductive strand 4.

[0036] Alternatively, a plurality of electrically conductive elements 4b, all helically wound in turns on the textile yarn 4a, can be provided, particularly when these elements are in the form of conductive threads. This improves the mechanical and electrical robustness of the strand 4. In particular, it ensures the electrical continuity of the electrically conductive strand 4, even after the breakage of one of the electrically conductive elements. In such a case, the winding directions may all be identical or different. Furthermore, the electrically conductive elements 4b are made of electrically conductive materials that may all be identical or different from one another.

[0037] The relatively small thickness of the conductive ribbon 4b or the diameter of the conductive wire combined with the textile nature of the wire 4a thus allows the second antenna to be flexible, and therefore to deform elastically or plastically when folded, without breaking.

[0038] To improve the robustness of the electrically conductive strand 4, particularly against chemical attack, this strand 4 can be fitted with a protective sheath. This sheath can be formed of a protective wire wrapped around the electrically conductive strand. Alternatively, or in addition, this sheath can be formed of a protective material, for example a resin, such as an epoxy resin, coating the electrically conductive strand 4 or coating the wrapped protective wire when the latter is present.

[0039] In addition to protection against chemical attacks, the protective sheath can prevent the ribbon from being torn off when the electrically conductive strand 4 is integrated (sewn, woven, embroidered) into the flexible support.

[0040] 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.

Claims

Demands

1. Radio frequency transmit-receive device (1) comprising: • a flexible support (2); • a radio frequency transmit-receive module (3) attached to the flexible support (2) and comprising a first antenna (3b) electrically connected to at least one electronic transmit-receive chip (3a); • a second antenna formed of an electrically conductive strand (4) attached to the flexible support (2) and capable of inductively coupling to the first antenna (3b), the second antenna comprising at least one textile yarn (4a) and at least one electrically conductive element (4b) wound helically in turns around the textile yarn (4a).

2. Radio frequency transmitting and receiving device (1) according to the preceding claim in which the second antenna (4) is sewn, woven or embroidered into the flexible support (2) or glued to the flexible support (2).

3. Radio frequency transmitting and receiving device (1) according to any one of the preceding claims wherein the second antenna (4) is provided with a protective sheath.

4. Radio frequency transmitting and receiving device (1) according to the preceding claim in which the protective sheath is formed of a protective wire, wrapped around the electrically conductive strand (4).

5. Radio frequency transmitting and receiving device (1) according to claim 3 in which the protective sheath is formed of a protective material enclosing the electrically conductive strand (4).

6. Radio frequency transmit-receive device (1) according to any one of the preceding claims wherein the textile yarn (4a) has a diameter between 50 micrometers and 100 micrometers.

7. Radio frequency transmitting and receiving device (1) according to any one of the preceding claims wherein the textile yarn (4a) is formed of synthetic fibers such as polyester or polyamide fibers.

8. Radio frequency transmitting and receiving device (1) according to any one of the preceding claims wherein the electrically conductive element (4b) is a conductive ribbon.

9. Radio frequency transmit-receive device (1) according to the preceding claim in which the conductive tape has a thickness of less than 10 micrometers, preferably less than 5 micrometers, more preferably less than 3.5 micrometers, or even less than 1.5 micrometers.

10. Radio frequency transmitting and receiving device (1) according to any one of the preceding claims wherein the electrically conductive element (4b) is made of a metal or a plurality of metals, such as a copper-silver alloy.

11. Radio frequency transmitting and receiving device (1) according to any one of the preceding claims wherein the electrically conductive element (4b) is covered with an electrically insulating coating, such as a varnish or enamel.

12. Radio frequency transmit-receive device (1) according to any one of the preceding claims wherein the radio frequency transmit-receive module (3) is attached to one face of the flexible support (2), for example by means of an adhesive material.

13. Radio frequency transmit-receive device (1) according to the preceding claim in which the radio frequency transmit-receive module (3) is coated with a protective material, such as a resin.

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