CHIPLOSE RFID LABEL TAPE

Description

[0001] The present invention relates to a chipless (customizable) RFID tag strip, also called a "chip-less RFID tag" strip. More particularly, the invention relates to a reel of chipless (customizable) RFID tag strip. The invention also relates to a method for preparing the chipless (customizable) RFID tag strip and its corresponding reel.

[0002] These labels will be advantageously included in radio frequency identification devices (known as "RFID", with "RF" denoting radio frequency) without a chip (personalized); by "device" we mean a package, a document, in particular a security document as well as possibly any object including a portion of the strip comprising at least one RFID label without a chip.

[0003] Data transmission systems using radio frequency identification (RFID) technology are commonly used to identify all types of objects and living beings (e.g., animals or humans) carrying a suitable device (tag). RFID technology has become increasingly widespread over the past few decades as a device for storing and transmitting information.

[0004] This RFID technology uses a radio tag, also called a transponder (from the English "transponder," a contraction of the words "transmitter" and "responder"), which is attached to an object, and a reader, also called an interrogator, to read and identify the tag. RFID technologies are generally classified into categories using "active" or "passive" tags. Active tags have a local power source (such as a battery) through which they send a signal to the reader; they are thus generally characterized by a relatively long signal range.In contrast, passive radio tags do not have an internal power source because their signal transmission energy comes from the reader itself, and in particular from the reception of the signal emitted by the reader; thus, passive radio tags have a much shorter signal range, generally less than 8 meters.

[0005] From a practical standpoint, RFID technology uses radio frequencies (“RF”) which have much higher material penetration characteristics than optical signals. Thus, compared to barcode labels, RFID technology allows for use in far more hostile environmental conditions; for example, RFID tags can be read through all kinds of materials such as paper, cardboard, wood, paint, water, dirt, dust, animal or human bodies, concrete, or even through the tagged item itself or its packaging. This has opened up a wide range of applications for RFID tags, including, for example, the identification of goods and people, particularly packaging, and vehicles (parking, tolls, etc.).), inventory management, electronic access cards, not forgetting all security documents such as, for example, a means of payment, such as a banknote, a check or a restaurant voucher, an identity document, such as an identity card, a visa, a passport or a driver's license, a lottery ticket, a transport ticket or even an entry ticket to cultural or sporting events.

[0006] There are mainly two types of RFID tags, tags including an integrated electronic circuit, called chip (electronic) tags, and tags not including an integrated electronic circuit, generally referred to in the technical field by the English term "chip-less RFID tags".

[0007] RFID tags (active or passive) typically include an antenna, an electronic circuit, and memory to store an identification code. The electronic circuit receives the signal emitted by the reader and, in response, transmits a modulated signal containing the identification code stored in memory within a specific frequency band. For passive RFID tags, some of the energy carried by the radio waves emitted by the reader is used to power the chip.

[0008] Due to the presence of electronic circuits (such as the RFID chip or antenna) in chip-based RFID tags, these tags have a significant production cost. It is primarily to reduce this cost that the development of chipless and antennaless tags has been proposed. This type of chipless RFID tag therefore requires neither integrated circuits nor discrete electronic components, such as transistors, inductors, capacitors, and / or antennas; their conductive geometry generates a specific behavior, notably a resonant one. This resonance characteristic at a given frequency allows chipless RFID tags to be printed directly onto an object at a lower cost than traditional RFID tags.

[0009] Among the various families of chipless tags, they can be distinguished by the presence or absence of an RF antenna on the tag itself. Typically, as with RF systems, this antenna's role is to capture a portion of the EM wave emitted by the reader, convert it into a guided wave at the tag, and then conduct it through a filter that generates the tag's code. This filtered signal, containing the identifier ("ID"), is then retransmitted towards the reader, most often using a second antenna that performs the same function as the first but in reverse. These RFID tags have been used primarily for proof-of-concept demonstrations of chipless technology; however, their applications are quite limited. The antennas are bulky and significantly increase the tag's size.Similarly, the antenna is generally very sensitive to its immediate environment, which can completely misalign it, rendering it unable to convert the radiated wave into a guided wave to feed the filter. This results in a loss of tag efficiency, notably a significant decrease in the read range when these antenna-equipped tags are placed on objects. To address these issues, chipless RFID tags without antennas, still based on the same information encoding principle, appeared in the 2010s, as illustrated in the following publications. E. Perret, S. Tedjini, V. Deepu, A. Vena, F. Garet and L. Duvillaret, Patents published under numbers FR2956232 (B1) and US8556184 (B2); and VENA, Arnaud, PERRET, Etienne, and TEDJINI, Smail. Chipless RFID based on RF encoding particle: realization, coding and reading system. Elsevier, 1st Edition - August 2, 2016.

[0010] The key difference between these tags and the objects of the present invention, sometimes called REPs (for "RF encoding particles"), lies in the fact that they do not involve different RF blocks—namely, an antenna section, an RF transmission line section, and a filter section—but simply resonant RF patterns that allow the identifier to be encoded based on the resonant frequencies they contain. These tags are artificial radar targets designed to resonate at specific frequencies and are compatible with the ability to encode an ID and also to retrieve the tag's ID from the backscattered signal acquired by the tag.

[0011] Increasing the encoding capacity of chipless radio frequency identification (RFID) tags, as well as the manufacturing of these tags, and in particular the industrial production of discriminating tags, represent significant challenges in the state of the art. While chipless RFID technology shows great promise, efforts are still underway to improve the read performance of chipless RFID tags. Read performance refers to the tag's ability to be read and identified; for example, increasing the tag's signal level (the useful signal carrying the tag's information) relative to other signals such as measurement noise or signals backscattered by other objects near the tag. Specific work on the tag itself, and especially on the materials it is made of, is essential to address the issues of read performance, manufacturing, and cost of these tags.The materials used to make the tags will indeed have a direct impact on the useful signal backscattered by the tag.

[0012] The applicant has thus developed multi-layered, chipless RFID tags that address, among other things, the issues of encoding capacity and read performance. As an example, we will cite the chipless RFID tags described and claimed in patent application WO2021 / 165422 A1, which concerns a chipless (personalized) radio frequency identification device and a corresponding tag.

[0013] ZA200607984 (A) describes a method for applying an RFID tag to an object, said tag comprising an antenna connected to an integrated circuit including a receiver and a transmitter. US2006289979 (A1) relates to smart tag module bridges for positioning chip modules on substrates and for bridging connection elements of the chip modules to connection elements of antenna elements disposed on or in the substrates.

[0014] Nevertheless, their manufacturing process, and more particularly their industrial manufacturing, remains an important challenge to which the present invention advantageously responds, as explained later in this description. Description of the invention

[0015] Thus, the present invention provides a promising solution to this problem by offering a chip-less (customizable) RFID tag strip, also called a "chip-less RFID tag" strip, and, in particular, a reel of chip-less (customizable) RFID tag strip. The present invention also relates to a method for preparing a chip-less (customizable) RFID tag strip and its corresponding reel. Band

[0016] In particular, the present invention relates to a chipless radio frequency identification tag strip, said strip comprising a dielectric substrate layer and patterns made of a conductive material layer representing the tag resonators, characterized in that the strip has dimensions of length L, width 1 and thickness "Ep" and in that it comprises grooves of depth "Pr" of the strip and oriented in the direction of the width of the strip.

[0017] The said grooves thus make it possible to advantageously integrate the strip subject to the present invention into an industrial roll-to-roll process (also known as roll-to-roll or "roll-to-roll processing" in English) while bringing many other advantages which will be described later in this description. Bloodletting

[0018] The cuts can be made by any suitable method, for example using a half-cut cutting tool. The cutting tool will advantageously be positioned within the industrial process for preparing the chipless radio frequency identification (RFID) label strip.

[0019] The chipless radio frequency identification (RFID) label tape according to the present invention therefore comprises grooves of depth Pr oriented in the direction of the tape's width; thus, when the tape is prepared or transported, said grooves are made perpendicular to the direction of travel of said tape. The depth Pr of the grooves will advantageously be selected so as to allow the tape to be wound into a reel without risk of tearing the tape and without affecting the integrity and characteristics of the patterns formed by a layer of conductive material representing the label resonators. By way of illustration, the depth of the grooves will be such that Pr > 1% of the tape's thickness Ep, for example, Pr > 5% of the tape's thickness Ep. The depth Pr of the grooves will advantageously be such that Pr < 90% of the tape's thickness Ep, for example, Pr < 50% of the tape's thickness Ep.The winding of the tape will thus be advantageously carried out on the side of the tape where the dielectric substrate layer has not been cut.

[0020] The kerf length will also be advantageously selected to allow the tape to be wound into a reel without risk of tearing the tape and without affecting the integrity and characteristics of the patterns made of a layer of conductive material representing the label resonators. For example, the kerf length will be greater than 80% of the tape width l, for instance, greater than 90% of the tape width l, preferably identical to the tape width l.

[0021] The width of the grooves will also be advantageously selected to allow the tape to be wound into a reel without risk of tearing the tape and without affecting the integrity and characteristics of the patterns made of a layer of conductive material representing the label resonators. This width will advantageously be as small as possible; it will therefore depend on the equipment used to generate said grooves. By way of illustration, the width of the grooves will be less than 0.5 mm, for example, less than 0.1 mm. However, and this constitutes a particular application according to the present invention, the shape of the grooves may advantageously be V-shaped, as this shape opens up other possibilities for winding the tape, as explained below in the description.

[0022] Any suitable measurement method can be advantageously used to measure the dimensions of the grooves. For example, we can mention the use of a profilometer and / or ultrasound and / or a microscope. Alternatively, it will suffice to determine the corresponding dimensions of the grooves by examining the cutting tool and the conditions under which the grooves were made.

[0023] The positioning of the grooves on the tape will also be advantageously selected so as to allow the tape to be wound to form a reel without risk of tearing the tape and without affecting the integrity and characteristics of the patterns made up of a layer of conductive material representing the label resonators.

[0024] "Esp" is defined in this disclosure (this including the description and claims that follow) as the spacing between two consecutive grooves (the grooves oriented in the direction of the width of the strip; also referred to as main grooves below).

[0025] Thus, in a particular embodiment of the present invention, when the strip has been wound or is intended to be wound onto a central cylindrical support element (for example a mandrel) whose diameter before winding is "Dia", the spacings between consecutive grooves "Esp" satisfy the following equation: Esp / 2 2 + Dia / 2 2 1 / 2 − Dia / 2 < 2 mm

[0026] Preferably, Esp / 2 2 + Dia / 2 2 1 / 2 − Dia / 2 < 1 mm

[0027] For example, Esp / 2 2 + Dia / 2 2 1 / 2 − Dia / 2 < 0 , 5 mm

[0028] Thus, in a particular embodiment of the present invention, when the strip has been wound or is intended to be wound on a central cylindrical support element (for example a mandrel) whose diameter before winding is "Dia" and whose diameter varies during winding "Dréel", the spacings between consecutive grooves "Esp" satisfy the following equation: Esp / 2 2 + Drée 1 / 2 2 1 / 2 − Drée 1 / 2 < 2 mm

[0029] Preferably, Esp / 2 2 + Drée 1 / 2 2 1 / 2 − Drée 1 / 2 < 1 mm

[0030] For example, Esp / 2 2 + Dréel / 2 2 1 / 2 − Dréel / 2 < 0 , 5 mm

[0031] In one embodiment according to the present invention, the grooves are arranged on the side of the tape facing the patterns formed by a layer of conductive material representing the label resonators. Although grooves could be intentionally positioned on certain resonators to modify their resonance characteristics, this would require considerable work in re-identifying the label, which would be incompatible with any efficient industrial process. Therefore, the grooves are advantageously positioned outside the label resonators so as not to alter their resonance characteristics, for example, between two successive resonators along the length of the tape.In a preferred embodiment of the present invention, the grooves will be positioned outside the patterns formed by a layer of conductive material representing the label resonators, either between two labels or groups of labels in the direction of the length of the strip. Although the grooves can be positioned at irregular intervals along the strip, regular spacing is preferred to facilitate the industrial manufacturing process of the strips with their grooves.

[0032] In an embodiment according to the present invention, the grooves are arranged on the face of the tape opposite the side of the patterns made of a layer of conductive material representing the label resonators. The positioning characteristics of these grooves will advantageously meet the same requirements as if the grooves had been positioned on the other face, namely: an orientation in the direction of the width of the tape (perpendicular to the direction of movement of said tape when the latter is prepared or transported); on portions of the tape whose positioning in the direction of the length L of the tape does not coincide with that of the label resonators so as not to modify their resonance characteristics, for example between two successive resonators represented by their virtual transverse image (through the tape) in the direction of the length of the tape;For example, outside the spaces corresponding to the transverse virtual image (across the tape) of the patterns made of a layer of conductive material representing the label resonators, either between two labels or groups of labels in the direction of the length of the tape. Although the grooves can be positioned at irregular intervals on the tape, regular spacing will be preferred to facilitate the industrial manufacturing process of the tapes with their grooves. As described above, a V-shaped groove will be particularly suitable for this method of grooving the tape on the side opposite the pattern made of a layer of conductive material, as it will allow the tape to be wound on the side with the grooves.

[0033] In a particular embodiment according to the present invention, grooves such as those defined above may advantageously be arranged on both faces of the strip; in this case, it will advantageously be avoided that the positioning in the direction of the length L of the strip of the grooves located on one side of the strip does not coincide with that of the grooves located on the other side of the strip in order to avoid any tearing of said strip.

[0034] In a particular embodiment of the present invention, additional grooves, different from those defined above, may advantageously be arranged on the strip perpendicular to the grooves already characterized above, which we shall call "main grooves"; these additional grooves will therefore advantageously be arranged along the length of the strip. They will also be positioned and sized so as not to affect the integrity and characteristics of the patterns made of a layer of conductive material representing the label resonators.Therefore, additional grooves will advantageously be positioned outside the label resonators so as not to alter their resonance characteristics, for example, between two successive resonators in the bandwidth direction and / or outside the patterns formed by a layer of conductive material representing the label resonators, or between two labels or groups of labels in the bandwidth direction. Their depths and widths and / or shape will preferably be defined in the same way as those of the main grooves; however, their lengths will be selected based on the dimensions of the labels and / or resonators.In one embodiment according to the present invention, the additional grooves are arranged on the face of the strip on the side of the patterns made of a layer of conductive material representing the label resonators, on the opposite face or on both faces of the strip.

[0035] As an illustration, according to the figure 2 Attached, you can see three examples of radio frequency identification (RFID) tag strips without chips, oriented lengthwise, with grooves / notches. For each example, you can see three conductive patterns positioned on the strip. The arrows indicate the direction of travel of the strip, i.e., the possibility of winding the strips into reels.

[0036] There figure 2(a) presents a strip with grooves of the smallest possible width. As mentioned above, this width will depend on the equipment used to generate said grooves.

[0037] THE figures 2(b) and (c) feature V-shaped grooves, a shape that opens up other possibilities for winding the band. Indeed, the grooves shown on the figure 2(b) allow the tape to be wound in such a way that the conductive patterns are on the outer face of the winding, while the figure 2(c) where the V shapes are on the opposite side of the patterns allow the strip to be wound so that the patterns are on the inner face (core side) of the reel when winding. Coil

[0038] The present invention also relates to a coil of radio frequency identification tag tape without a chip, said tape comprising a layer of dielectric substrate and patterns made of a layer of conductive material representing the tag resonators, characterized in that the tape of the coil has dimensions of length L, width 1 and thickness Ep and in that it comprises grooves of depth Pr of the tape and oriented in the direction of the width of the tape.

[0039] In a preferred embodiment according to the present invention, all the aforementioned bleeding characteristics will also advantageously apply to the reel strip that is the subject of the present invention.

[0040] The reel that is the subject of the present invention is therefore the winding of the radio frequency identification (RFID) label strip without a chip. This reel may advantageously also include any element facilitating its manufacture, handling, and / or transport; the weight of the strip preferably representing at least 90% of the total weight of the reel.

[0041] In a preferred embodiment, the reel of the present invention comprises a central cylindrical support element around which said strip is wound.

[0042] Any type of central cylindrical support element for winding the chipless radio frequency identification label strip of the subject of the present invention may advantageously be used within the framework of the present invention provided that its characteristics, in combination with the dimensional characteristics of the aforementioned strips and grooves, allow the strip to be wound on said element without risk of tearing the strip and without affecting the integrity and characteristics of the patterns made up of a layer of conductive material representing the label resonators.

[0043] For illustrative purposes, the central cylindrical support element is a core (for example made of metal or cardboard); however, the present invention also covers reels without cores, such as certain toilet paper rolls.

[0044] As a reminder, "Esp" is defined as the spacing between two consecutive cuts (cuts oriented in the direction of the width of the band; also called main cuts above).

[0045] "Dia" is defined in this disclosure (the description and the claims that follow) as the diameter of the central cylindrical support element (e.g., the mandrel) before winding; this diameter therefore does not take into account the thickness of the strip wound on said support. Dia is preferably between 25 mm and 305 mm.

[0046] "Dreel" is defined in this disclosure (the description and the claims that follow) as the diameter of the reel of chipless radio frequency identification (RFID) label tape; this diameter is the sum of the diameter of the central cylindrical support element (e.g., the core) and the thickness of the tape wound onto said support element. Dreel changes as the tape is wound. Dreel is preferably between 25 mm and 1250 mm, for example, after winding, between 50 mm and 1000 mm. The ratio of the maximum diameter of the wound reel of tape divided by the diameter of its core is preferably between 2.5 and 20, for example, between 2.5 and 10, or for example, between 2.5 and 4.

[0047] To facilitate calculations and understanding of the dimensions discussed in the present invention, and unless otherwise indicated, the dimensions are systematically represented in millimeters (mm).

[0048] In a particular embodiment according to the present invention, the spacings between consecutive cuts "Esp" satisfy the following equation: Esp / 2 2 + Dia / 2 2 1 / 2 − Dia / 2 < 2 mm

[0049] Preferably, Esp / 2 2 + Dia / 2 2 1 / 2 − Dia / 2 < 1 mm

[0050] For example, Esp / 2 2 + Dia / 2 2 1 / 2 − Dia / 2 < 0 , 5 mm

[0051] In a particular embodiment according to the present invention, which takes into account the increase in the actual diameter of the coil as it is wound, resulting in a possibility of a gradual increase in the spacing between grooves, the spacings between consecutive grooves "Esp" satisfy the following equation: Esp / 2 2 + Dréel / 2 2 1 / 2 − Dréel / 2 < 2 mm

[0052] Preferably, Esp / 2 2 + Dréel / 2 2 1 / 2 − Dréel / 2 < 1 mm

[0053] For example, Esp / 2 2 + Dréel / 2 2 1 / 2 − Dréel / 2 < 0 , 5 mm

[0054] "Ec" is defined in this disclosure (the description and the claims that follow) as the gap at any point of winding of the web between the lower surface of the web and its winding support (the support element) during the first winding turn; "EcMAX" being the largest gap. Although the objective of the invention, with its grooves, is to approach a perfect winding that conforms to the circumference of the core, it is reasonable to accept a gap EcMAX greater than 0.01 mm, for example, greater than 0.1 mm. Preparation of tapes and tape reels

[0055] The present invention also relates to a method for preparing the chipless RFID label strip (personalized) and its corresponding reel. Any prior art roll-to-roll process may advantageously be used within the scope of the present invention, provided that it incorporates the requirements related to the dimensions of the reels and the aforementioned grooves. The method for preparing the chipless radio frequency identification label strip and / or its corresponding reel according to the present invention advantageously uses a roll-to-roll process that incorporates a cutting station for making the grooves.

[0056] The applicant has observed that the present invention makes it possible to reproducibly maintain the coding capabilities and read performance of labels thus manufactured on tape / reel with their slits, whereas this was not possible when the slits were not made in accordance with the present invention. Without wishing to be limited by this explanation, the applicant believes that the maintenance of coding capabilities and read performance has been made possible by improved control of the tape curvature at critical points, namely those near the labels and their resonators. Thus, a minimum distance between the slits and any resonator is preferred; for example, any slit will be more than 1 mm, or even more than 2 mm, from any resonator and / or resonator pattern.

[0057] In a preferred embodiment according to the present invention, all the features mentioned below will also apply advantageously not only to the tape that is the subject of the present invention but also to the tape of the reel that is the subject of the present invention.

[0058] For illustrative purposes, the dielectric substrate layer of the chipless radio frequency identification tag strip of the present invention may be selected from solid foam, foam board, corrugated board, honeycomb board or fabric (for example a material made of interlaced yarns or fibers of cotton, hemp, linen or synthetics such as nylon, polyamide or viscose).

[0059] As described in more detail in the following description, solid foam is preferably understood to be a dielectric material which may be rigid or flexible, which contains a significant percentage of air or gas bubbles and which therefore, while occupying a certain volume, contains very little matter in the solid state, the solid state preferably being a state of matter characterized by the absence of freedom between molecules or ions; thus, a foam is generally characterized by a very low relative permittivity, namely close to 1, 1 being the value of the permittivity of air.

[0060] This dielectric substrate and conductive pattern assembly according to the present invention makes it possible to obtain tags that not only exhibit optimal resonance characteristics but also superior radiation efficiency and read performance; thus, it is at least the sum of the two layers, dielectric and conductive pattern, that defines the resonance characteristics of the tags on the tape and reel of the present invention. This makes it possible to easily identify RFID tags without corresponding chips (their RF signature remaining recognizable) while also facilitating their manufacture.

[0061] Within the framework of the present invention, the use of the qualifier "personalised" for the labels simply confirms that the identification / discrimination of said label is possible. Dielectric substrate

[0062] The chipless radio frequency identification tag strips according to the present invention are therefore characterized in that they comprise a dielectric substrate layer.

[0063] This dielectric substrate will advantageously be selected from among dielectric substrates meeting at least one, two or all three of the following properties: an apparent density less than 250 kg.m⁻³; for example, less than 100 kg.m⁻³; and / or a relative permittivity less than 3; preferably less than 2; preferably less than 1.25. For example, this relative permittivity will be less than 1.10. In a particular embodiment according to the present invention, this relative permittivity will be close to 1. This relative permittivity will preferably be greater than 1.001. For example, this relative permittivity will be greater than 1.01; and / or a loss angle tangent value less than 10⁻², preferably less than 10⁻³, for example, less than 2.10⁻⁴.

[0064] We will cite by way of illustration a dielectric substrate having an apparent density between 25 and 75 kg.m -3; a relative permittivity between 1.05 and 1.09; and a value of loss angle tan δ between 10 -5 and 2.10 -4 at a frequency of 3.9 GHz.

[0065] This particular dielectric substrate will advantageously be selected from among solid foam dielectric substrates, foam board, corrugated board, honeycomb board or fabric dielectric substrates (for example in a material made of interlaced yarns or fibers of cotton, hemp, linen or synthetics such as nylon, polyamide or viscose).

[0066] This dielectric substrate will advantageously be rigid or flexible; it will preferably be in the form of a film.

[0067] The thickness of the dielectric substrate will advantageously be greater than 0.1 mm. This thickness will preferably be greater than 0.5 mm. For example, this thickness will be greater than 0.75 mm.

[0068] The thickness of the dielectric substrate will advantageously be less than 10 mm, for example equal to or less than 5 mm. This thickness will preferably be less than 3 mm. This thickness will, for example, be less than 1.5 mm.

[0069] Any dielectric substrate meeting the reading, resonance, and discrimination performance objectives of the present invention may advantageously be used within the scope of the present invention. Examples include fabric (for example, a material made of interlaced yarns or fibers of cotton, hemp, linen, or synthetics such as nylon, polyamide, or viscose), corrugated cardboard, honeycomb cardboard, foam board, solid foam, for example, polymers or biopolymers.

[0070] In a particular embodiment of the present invention, the dielectric substrate is characterized by its apparent density, which is less than 250 kg / m³; for example, less than 100 kg / m³. The apparent density can be measured by any suitable method, for example, by weighing. Unless otherwise specified, densities are given for materials at a temperature of 20 °C under normal atmospheric pressure (1013 hPa). Advantageously, any ASTM or ISO method applicable to the type of material selected as the dielectric substrate may also be used to measure this apparent density; regardless of the ASTM or ISO method chosen (and applicable to the type of material selected), the measurement of the apparent density will therefore preferably be less than 250 kg / m³; for example, less than 100 kg / m³.

[0071] In a particular embodiment of the present invention, the dielectric substrate is characterized by its dielectric properties, namely a relative permittivity of less than 3, preferably less than 2. This relative permittivity will preferably be less than 1.25. For example, this relative permittivity will be less than 1.10. In a particular embodiment of the present invention, this relative permittivity will be close to 1. This relative permittivity will preferably be greater than 1.001. For example, this relative permittivity will be greater than 1.01.

[0072] In a particular embodiment according to the present invention, the dielectric substrate is characterized by its dielectric properties, namely a loss angle tangent value less than 10⁻², preferably less than 10⁻³, for example less than 2.10⁻⁴.

[0073] As a reminder, dielectric permittivity is a physical property that describes the response of a material when an electric field is applied to it; and the tangent of the loss angle is also called the dielectric dissipation factor.

[0074] The relative permittivity and loss angle tangent (tan δ) can be measured by any suitable method. For example, dielectric spectroscopy or resonant cavity spectroscopy are commonly used dielectric analysis techniques. These techniques are based on measuring the complex impedance of a sample at a given frequency and / or temperature. The present invention relates to applications at temperatures around ambient temperature (typically between -20°C and +80°C). Within this temperature range, the permittivity and dielectric losses of commonly found dielectric materials can be considered relatively constant, particularly in the band of interest, which is the ULB band between 3 GHz and 10 GHz.

[0075] This method allows access to the permittivity value of a material or its loss factor tan δ at a given frequency, for example. The values ​​indicated in this description and the following claims correspond to those measured at any frequency within the 3 GHz to 10 GHz frequency band, at a temperature of 20°C.

[0076] In particular, the values ​​shown in the following examples were measured using the Damaskos Model 08 ("Thin Sheet Tester - Cavity"), which provides an excellent estimate of the dielectric permittivity of dielectric substrates. This Damaskos thin sheet tester also provides a non-destructive measurement of the dielectric loss tangent in the 800-4000 MHz band, making it particularly well-suited to our substrates. The measurement is performed on common vector and scalar analyzers under the control of the Damaskos equipment, and the data is processed using the "Cavity" software sold by Damaskos, resulting in very good repeatability. Solid foam

[0077] Solid foam (for example, polymer foam) is a solid foam used, for example, in many applications such as thermal insulation, acoustic insulation, packaging, automotive, etc. This foam can be likened to a continuous solid network containing trapped gas bubbles (usually air), which allows it to combine the properties of a foam (density, lightness) with those of a solid.

[0078] Solid foam can advantageously be characterized by its nature, density, closed or open cell structure, bubble size, and the arrangement of said bubbles in space.

[0079] A solid foam is considered low-density when it contains more than 90% gas, corresponding to an apparent density of less than 100 kg / m³. A medium-density foam has an apparent density between 100 and 600 kg / m³. Finally, a high-density solid foam contains less than 60% gas, corresponding to an apparent density greater than 600 kg / m³. Apparent density can be measured by any appropriate method, for example, by weighing. Unless otherwise specified, densities are given for substances at a temperature of 20 °C and under normal atmospheric pressure (1013 hPa).

[0080] The solid foam used in the context of the present invention will preferably have an apparent density of less than 250 kg.m⁻³. For example, it will have an apparent density of less than 100 kg.m⁻³.

[0081] The solid foam used in the context of the present invention will preferably have a bubble density between 10⁴ and 10⁹ bubbles / cm³. For example, it will have a bubble density between 10⁵ and 10⁸ bubbles / cm³.

[0082] The solid foam used in the context of the present invention will preferably have a bubble size with an average diameter of between 5 microns and 1 millimeter. For example, it will have an average diameter of between 20 microns and 200 microns.

[0083] Any material exhibiting the foam characteristics defined within the scope of the present invention may advantageously be selected. Examples include foam board, polymers, and biopolymers. A polymer is generally understood to be a structure composed of several macromolecules (molecules made up of repeating subunits); generally, a material is considered a polymer when its molar mass exceeds 2,000 g / mol.

[0084] In a particular embodiment of the present invention, the solid foam shall be a polymer foam, for example, a polymer selected from thermosets such as polyurethanes, epoxies, etc., or, preferably, from thermoplastics such as polystyrene, polyvinyl chloride, polypropylene, polyethylene, polyethylene terephthalate (PET), and / or a mixture of one or more of these polymers. A foam comprising more than 80% by weight, for example, more than 90% by weight, of extruded polystyrene, polyethylene (PE), or polyethylene terephthalate (PET) shall advantageously be selected within the scope of the present invention.

[0085] The morphology of foams, particularly bubble size and density, can be determined by any appropriate method. For example, the foam (e.g., polymer foam) is fractured under liquid nitrogen to position itself below the polymer's glass transition temperature. Since the fracture surface is clean, the bubbles are not deformed and can be observed, for instance, by microscopy. Preferably, an electron microscope coupled with image analysis software capable of counting the number of bubbles and calculating the average bubble area for each image is used. This allows the average bubble diameter to be determined, as well as the equivalent average diameter when the bubbles are not spherical. The bubble density (the number of bubbles per cm³) is determined by the formula (n / A)(3 / 2), where n is the number of bubbles in the image and A is the image area.

[0086] Polymer foam can be prepared by any suitable method. We will cite by way of illustration physical foaming with gas injection (for example CO2 or dinitrogen (N2)) or chemical foaming with addition and decomposition of a blowing agent (for example 5-Phenyltetrazole, p-Toluene sulfonyl semicarbazide, Dinitrospoenta-methylenetetramine, p-Toluene sulfonyl hydrazide, pp-Oxybis(benzene)sulfonyl hydrazide and / or Azodicabonamide which is preferentially used).

[0087] An extrusion blow molding process is particularly suitable for the preparation of a polymer foam film that can be used within the framework of the present invention, in particular a polystyrene foam film in roll form with or without adhesive.

[0088] Nucleating agents can advantageously be added to the polymer, making it possible to obtain small bubbles. Examples include inorganic fillers (e.g., stearic acids, calcium stearate, zinc stearate, calcium carbonate, magnesium silicate, talc, sodium benzoate), organic phases such as elastomers and / or rubber particles, carbon black, and / or nanoparticles such as nano clays or carbon nanoparticles (e.g., nanotubes).

[0089] In a particular embodiment of the present invention, the solid foam will be selected from foam boards, also known as foam board; this type of material generally consists of two or three layers, including a main layer (inner if three layers) of polymer foam (for example, polystyrene, polyurethane, polyethylene, and / or polyethylene terephthalate (PET)) covered on the outside with a thin film, for example, paper or plastic. The type of paper or plastic representing the optional top layer of the dielectric substrate is not critical because it represents a negligible thickness compared to that of the solid foam, as explained in detail below. However, this stacking of dielectric layers makes the invention even more relevant because it exacerbates the problems related to the rigidity of this stack (or sandwich, depending on the number of layers).

[0090] In general, and in a particular embodiment according to the present invention, the dielectric substrate (for example solid foam, foam board, corrugated board, honeycomb board and / or fabric, preferably solid foam) with its characteristics as described herein represents at least 95% by volume and / or 95% by thickness and / or 95% by weight of the entire dielectric substrate of the strip which is the subject of the present invention, preferably at least 99% by volume and / or 99% by thickness and / or 99% by weight of the entire dielectric substrate.The present invention therefore also relates to a chipless RFID tag strip comprising (see consisting of) a dielectric substrate which itself consists of a dielectric substrate with its characteristics as described above (and / or claimed) and one or more thin dielectric layers, for example a thin dielectric layer on which is / are affixed the pattern(s) consisting of a layer of conductive material; this / these thin dielectric layer(s) (for example a film of paper or cardboard or plastic material (for example: a film of polyethylene (PE), polypropylene (PP) or preferably polyethylene terephthalate (PET)) advantageously represents less than 5%, or even less than 1%, of the thickness of the entire dielectric substrate.

[0091] Although optional and not critical, the Applicant has found that this thin dielectric layer or dielectric film provides many additional advantages to the RFID tag that is the subject of the present invention, subject to a few preferred requirements.

[0092] First, it is important to mention that the relative permittivity and loss angle tangent values ​​of the corresponding dielectric stack of the label strip of the subject of the present invention will always have values ​​corresponding to the characteristic values ​​already cited above (and / or claimed below); the influence of the additional dielectric film (or additional films) on the dielectric assembly will therefore be insignificant compared to these criteria.

[0093] Next, and this represents a considerable advantage of an embodiment according to the present invention, the Applicant found that the flatness and / or surface condition of the dielectric surface on which the conductive pattern was affixed could also represent an additional problem in the production of the label; indeed, as it frequently happens that the upper layer of the main dielectric (for example solid foam, foam board, corrugated board, honeycomb board and / or fabric, preferably solid foam) of the label does not have good flatness and / or a good surface condition, the use of an additional dielectric film made it possible to obtain better results / performance because, among other things, it provided this flatness and / or surface condition required.Thus, by having pattern(s) consisting of a layer of conductive material applied to this dielectric film, improved performance has been achieved. Any suitable method may be used to characterize the flatness and / or surface condition of the conductive film. By way of illustration, and to avoid having to consider measurements that are difficult to implement, the label strips of the present invention will advantageously be characterized by a total thickness at any point of the label resonators (see at any point of the label) that varies from less than one hundred (100) microns, preferably less than fifty (50) microns, for example less than forty (40) microns, less than twenty (20) microns, less than ten (10) microns, or even, for example, less than two (2) microns.The application of the pattern(s) consisting of a layer of conductive material directly onto this dielectric film can be carried out by any appropriate method as explained below in the description, for example by printing, for example by inkjet printing.Next, the dielectric film covered with the pattern(s) made of a layer of conductive material can be added to the main dielectric substrate (solid foam, foam board, corrugated board, honeycomb board and / or fabric, preferably solid foam) in any direction / order; the Applicant even found an advantage in carrying out the successive stacking (1) main dielectric substrate - (2) conductive pattern - (3) dielectric film - because this stacking made it possible to advantageously protect the conductive patterns during the handling and / or use of the label since these patterns were protected both on one side by the main dielectric substrate and on the other side by the dielectric film.

[0094] In a particular embodiment, the dielectric film is characterized by one, two, or more of the following characteristics: a relative permittivity measured at any frequency between 3 and 10 GHz higher than that of the main dielectric substrate (solid foam, foam board, corrugated board, honeycomb board and / or fabric, preferably solid foam); preferably a relative permittivity greater than 1.25, for example greater than 2; preferably a relative permittivity less than 3.5; and / or a loss angle tangent value measured at any frequency between 3 and 10 GHz higher than that of the main dielectric substrate (solid foam, foam board, corrugated board, honeycomb board and / or fabric, preferably solid foam); preferably a loss angle tangent value less than 2.10 -2< ; and / or a thickness at least ten times less than that of the main dielectric substrate (solid foam, foam board, corrugated board, honeycomb board and / or fabric, preferably solid foam); preferably a thickness less than 100 microns, for example less than 50 microns; and / or made of plastic material, for example polyethylene, polypropylene or polyethylene terephthalate. .

[0095] In a particular embodiment, the main chemical composition of the dielectric film is identical to that of the main dielectric substrate. For example, if the main dielectric substrate is polyethylene terephthalate foam, the additional dielectric film will also be polyethylene terephthalate-based. Cardboard

[0096] As previously stated, the dielectric substrate according to the present invention may, by way of illustration, be selected from corrugated cardboard or honeycomb cardboard. By way of illustration, corrugated cardboard will be selected from B-flute cardboard (also called PC, generally with a thickness between 2.5 and 3.5 mm), E-flute cardboard (also called micro-flute, generally with a thickness between 2 and 1.5 mm); F-flute cardboard (also called Minimicro, generally with a thickness of about 1.2 mm), G-flute or N-flute cardboard (called Nano-flute) with a thickness of about 0.8 mm, O-flute cardboard with a thickness of about 0.5 mm, or a mixture of two or more of the aforementioned cardboards.

[0097] The cardboard used in the context of the present invention will preferably have an apparent density of less than 250 kg.m⁻³. For example, it will have an apparent density of less than 100 kg.m⁻³.

[0098] In a particular embodiment of the present invention, the chipless RFID tag strip comprising a dielectric substrate and one or more patterns made of a conductive layer is characterized in that the upper part of the dielectric substrate is in contact with the pattern(s) made of a conductive layer. Indeed, in addition to the advantages related to the flat / smooth surface of the upper part of the dielectric substrate mentioned above, the Applicant has also discovered that it is preferable to avoid the presence of any other material between these two layers (substrate / optional film / conductive patterns); for example, no adhesive is used between these two parts of the tag. Conductive layer

[0099] The chipless radio frequency identification (RFID) tag strips according to the present invention are characterized in that they comprise a dielectric substrate and patterns made of a layer of conductive material. In a particular case specific to the present invention, the strips also comprise, beneath the dielectric substrate, one or more layers of conductive material; preferably across the entire surface of the dielectric substrate. The configuration comprising two conductive layers, one beneath the dielectric substrate and the pattern(s) above the dielectric substrate, is a particularly interesting case for the invention (dielectric substrate sandwiched between the two conductive layers), as explained below in the description of tags with a ground plane.

[0100] In a particular embodiment according to the present invention, the material of the conductive layer constituting the pattern comprises (or preferably consists of) a material selected from the group consisting of graphite, copper, nickel, silver, aluminum, platinum and / or mixtures thereof, preferably copper and / or silver and / or aluminum.

[0101] In a particular embodiment of the present invention, the conductive layer constituting the pattern is characterized by a thickness of conductive material greater than 100 nm. For example, a thickness of more than 150 nm may be used. For example, a thickness of more than 200 nm may be used. For example, a thickness of more than 250 nm may be used. For example, a thickness of more than 300 nm may be used. For example, a thickness of more than 400 nm may be used. For example, a thickness of more than 500 nm may be used.

[0102] In a particular embodiment of the present invention, the conductive layer constituting the pattern is characterized by a conductive material thickness of less than 20 microns. Preferably, the conductive material thickness will be less than 10 microns, or even less than 2 microns. For example, a thickness of less than 1.5 microns may be used.

[0103] For illustrative purposes, the conductive material layer can be deposited, preferably directly onto the dielectric substrate or onto the optional dielectric film, by any suitable deposition method.

[0104] According to the present invention and in a particular manufacturing embodiment, the dielectric substrate is generally in the form of a film reel. This film moves, generally by means of a film transport system in a roll-to-roll printing machine, along a transport path oriented along a longitudinal axis from at least one film unwinding reel to at least one film winding reel for the printed and / or personalized film, and thus covered with the conductive material patterns according to the present invention.

[0105] As an example of a suitable method for manufacturing the tag, we will cite a conductive ink printing method, in particular a digital conductive ink printing method, and more specifically a digital on-demand inkjet printing method. This on-demand inkjet printing method preferably uses piezoelectric printheads.

[0106] We will also cite, by way of illustration, as a suitable alternative method for depositing a pattern consisting of a layer of conductive material, a method that comprises a digital printing step of a first pattern consisting of a printing product, preferably dielectric, such as an ink, varnish, and / or toner, followed by a step of depositing, by overlaying on the first printed pattern, an identical pattern consisting of a conductive film comprising an application film in contact with the printing product and a conductive film. We will cite, by way of illustration, any digital printing method as a suitable method for the printing step of the first pattern, more particularly a digital on-demand jet printing method. This on-demand jet printing preferably uses piezoelectric printheads.For example, the step of applying the film to the first pattern is carried out under pressure and temperature conditions resulting in selective co-adhesion between the printing product and the film application film, for example by means of one or more sets of pinch rollers and / or one or more pressure rollers.

[0107] We will also cite, by way of illustration, as a suitable alternative method for the method of depositing a pattern consisting of a layer of conductive material, a method by thermal transfer of the conductive material.

[0108] We will also cite, as an illustrative example, the method of successively assembling films / layers together as a suitable and preferred alternative for producing the tag strip. In this example, the conductive film that makes up the patterns representing the tag resonators can be manufactured either by printing as described above or by chemical treatment as described below.

[0109] By way of illustration and schematic representation, the tape that is the subject of the present invention may advantageously be made as follows: a roll of conductive film is manufactured or purchased, comprising a dielectric layer (corresponding to that described as optional above), an optional adhesive layer, and a conductive layer. For example, a roll of metal film (represented in the illustrations below by the example of aluminum) ALU / PET is made with adhesive: -------- ALUMINUM -------- with an illustrative thickness of 5 to 20 µm (tested at 6 µm) ------- Adhesive -------- (optional) -------- PET --------

[0110] In the case of labels with a ground plane, a similar or identical coil may advantageously be used for the solid conductive layer located on the other side of the main dielectric layer; alternatively, a metal coil may also be used.

[0111] Then a protective varnish is applied to form the design of the tag on the aluminum face (the varnish only protects the aluminum used for the tag).

[0112] Next, this layer with the varnish will advantageously be immersed in a chemical bath (for example, solutions based on caustic soda or caustic potash) which will remove the aluminum that is not protected by the varnish.

[0113] Next, the layers must be assembled. In the example below, the dielectric substrate layer is represented by the foam, and the case "with a ground plane" is illustrated. This assembly will therefore be carried out, illustratively, using the coil-to-coil method as previously described.

[0114] An illustration of the corresponding successive layers is shown below: ----- VARNISH ------ representing the tag -------- ALUMINUM -------- representing the tag with a thickness of 5 to 20 µm ------- Glue -------- (optional) -------- PET -------- ------- Glue -------- (optional) ---- FOAM ---- ------- Glue -------- (optional) -------- PET -------- (optional) -------- ALUMINUM -------- (representing the ground plane)

[0115] Thus, and this constitutes a preferred embodiment according to the present invention, the strip of the chipless RFID tag will be formed successively from bottom to top of an optional but preferred conductive layer, surmounted by an optional but preferred dielectric film, surmounted by the main dielectric substrate (for example solid foam, foam board, corrugated board, honeycomb board and / or fabric, preferably solid foam), surmounted by a dielectric film on which is affixed the pattern(s) consisting of a layer of conductive material, said conductive patterns being able to be located either on the upper part of the label, or advantageously between the main dielectric substrate and the dielectric film.

[0116] The present invention therefore relates to a strip of tags that possess resonance characteristics. In a particular embodiment according to the present invention, the tag is made up of the dielectric substrates and conductive layers described above. Tag

[0117] By way of illustration, the chipless (personalized) RFID tag according to the present invention has the following characteristics: • A conductive pattern or set of conductive patterns characterizing its geometry, preferably with at least one or more or all of the patterns being asymmetric, • An identifier that includes at least one resonant frequency fr and, preferably, at least one quality factor Q, • Resonating in an ultra-wide frequency band (ULB) characterized by a bandwidth greater than or equal to 500 MHz, preferably between 3.1 and 10.6 GHz, • With or without a ground plane, and • Polarizing or preferably Depolarizing. Tag - Geometry

[0118] For example, the Figure 1 shows different geometries of tags with ground planes specifically created within the framework of the present invention. This Figure 1The image illustrates four tags, each with six resonators. Two families of resonators (double L shape - in dark gray - and double parallel line shape inclined at 45° - in light gray) are used to optimize tag performance. The frequency band in which the resonant frequencies of each tag lie is indicated in the bottom left corner of each tag. Different tag geometries are shown. Tag - Identifier

[0119] The tag according to the present invention will preferably be characterized by an identifier that includes at least one resonance frequency fr and at least one quality factor Q. Resonant Tag

[0120] The tag according to the present invention is therefore resonant in an ultra-wide frequency band (ULB) characterized by a bandwidth greater than or equal to 500 MHz, preferably between 3.1 and 10.6 GHz. Passive Tag

[0121] As explained in the introduction, our type of chipless radio frequency identification device requires neither an integrated circuit nor discrete electronic components, such as a transistor, coil, capacitor, or antenna. This type of device is therefore characterized by passive behavior, as it does not require a local power source (such as a battery).

[0122] The tag can therefore easily characterize packaging, documents, labels, including security documents, and possibly any object and / or living being on which RFID identification marking without a chip can be carried out or on which a marking medium can be applied. Tag with or without site plan

[0123] The tag according to the present invention can be characterized in that it has or does not have a ground plane. In its simplest expression, a tag with a ground plane according to the present invention is defined as a structure comprising a flat dielectric substrate with a thickness generally less than 3 mm and generally greater than 100 µm sandwiched between two metallic layers (the conductive pattern layer above the dielectric substrate and the other conductive layer located below the dielectric substrate).

[0124] Thus, the strip which is the subject of the present invention will be advantageously characterized in that it comprises a conductive layer on the face of the dielectric substrate layer located opposite that comprising the patterns made up of a layer of conductive material.

[0125] For illustrative purposes, the thickness of the conductive layer (located under the dielectric substrate when the patterns consisting of a layer of conductive material are located above said dielectric substrate) will be advantageously selected from the following thicknesses.

[0126] In a particular embodiment of the present invention, the conductive layer located beneath the substrate is characterized by a thickness of conductive material greater than 100 nm. For example, a thickness of more than 150 nm may be used. For example, a thickness of more than 200 nm may be used. For example, a thickness of more than 250 nm may be used. For example, a thickness of more than 300 nm may be used. For example, a thickness of more than 400 nm may be used. For example, a thickness of more than 500 nm may be used.

[0127] In a particular embodiment of the present invention, the conductive layer located beneath the substrate is characterized by a conductive material thickness of less than 20 microns, for example, less than 10 microns, or even less than 2 microns. A thickness of less than 1.5 microns may be used, for example. A thickness of less than 1 micron may also be used.

[0128] In a particular embodiment according to the present invention, the total of the layers (conducting motif - dielectric - conductive layer) may, for example, have a thickness of 0.1 to 3 mm.

[0129] Although we talk about tagging with or without a ground plane, in the technique, the term "ground plane" is often associated with the metallic layer (located under the substrate) whose surface preferably corresponds totally to that of the substrate.

[0130] In a particular embodiment of the present invention, the material of the conductive layer constituting the ground plane comprises (or preferably consists of) a material selected from the group consisting of graphite, copper, nickel, silver, aluminum, platinum, and / or mixtures thereof, preferably copper and / or silver and / or aluminum. In a particular embodiment of the present invention, the material of the conductive layer constituting the ground plane is different from or identical to that of the conductive pattern, preferably identical.

[0131] Will the second metallic layer (the pattern(s)) be shaped to present a particular geometric form corresponding to the patterns of the tag (like the patterns shown on the figure 1A tag with a ground plane is therefore a structure comprising two metallic layers, while its counterpart without a ground plane has only one layer, namely the one where the tag's design is created. A tag with a ground plane has the advantage, once positioned with the ground plane facing an object, of electromagnetically isolating the tag from the object. In this case, the object's influence on the tag is less compared to a tag without a ground plane.

[0132] It should also be noted that a ground plane tag is a special case of a tag with two metallized layers where the substrate is sandwiched between them. In this preferred configuration, one of the two layers is ideally fully metallized. However, intermediate tag configurations are possible. For example, a ground plane tag might have openings (removals of metallic areas) on the ground plane side to achieve specific behavior. This can, for instance, create new resonances or modify existing ones on the first conductive layer. These openings can also improve the isolation of the various resonators in the second metallic layer, thus enhancing the decoupling of these resonances and potentially improving the tag's read performance.

[0133] The conductive material layer of the ground plane can be deposited, preferably directly onto the dielectric substrate, by any suitable deposition method. The deposition methods mentioned above for the deposition of conductive motifs will be repeated as an illustration.

[0134] It should also be noted that a chipless tag with two conductive layers and a dielectric layer in between can, for cost reasons, also be made by surrounding the substrate with the conductive layers, for example by folding. In this case, the conductive layer can have a surface area at least twice that of the substrate, typically a width at least twice as large with the same length. Once this surface, containing the conductive patterns and / or the ground plane, is fabricated, it is advantageously transferred all at once around the dielectric layer. This is possible by folding it completely around the surface. The only difference compared to the traditional approach (transferring the two metallized layers one by one to each face of the dielectric) is the presence of the metallized layer on one or more sides of the dielectric.If this part is not metallized, there is no significant difference compared to the more traditional approach. However, the possibility of metallizing this part (one or more sides of the dielectric) will allow for the creation of more complex structures, such as a resonant cavity with metallic walls, which will improve the quality factor. Thus, a skilled professional can take advantage of this structure, which is also generally simpler to manufacture because it requires fewer steps. Indeed, this approach reduces the number of technological steps: printing a single conductive substrate and bonding a single substrate.

[0135] In a particular application mode according to the present invention, the dielectric substrate (with or without a ground plane) will be selected from commercial materials used for thermal or acoustic insulation whose characteristics correspond to the characteristics of the present invention (and / or those claimed in the present invention); and the desired conductive patterns will be applied directly to these commercial materials.

[0136] The present invention is therefore advantageously applicable to tags both with and without a ground plane. Depolarizing tag

[0137] The tag according to the present invention will preferably be characterized by the fact that it is polarizing or, preferably, depolarizing. A depolarizing tag is a tag capable of emitting a wave with a polarization oriented perpendicular to that incident (this is then referred to as cross-polarization reflection).

[0138] In a particular embodiment according to the present invention, the chipless RFID tag strip has a ratio between the total upper surface of the dielectric substrate and the upper surface of the dielectric substrate covered with pattern(s) consisting of a layer of conductive material greater than 2.

[0139] In a particular embodiment according to the present invention, the chipless RFID tag strip with ground plane has a ratio between the lower surface of the dielectric substrate covered with the conductive material layer and the total lower surface of the dielectric substrate greater than 0.9. Drive

[0140] For illustrative purposes, in the context of the present invention, the reader is a transmitter-receiver reader of electromagnetic waves; the operating principle of said reader is based on the emission of an electromagnetic signal towards the identification tags which will return said signal according to their geometry (and for example their own resonance characteristics) and on the capture by the reader of said reflected signal - thus, the processing of the received signal (in particular through a decoding step) will make it possible to retrieve the information contained in the label / tag.

[0141] Thus, in general, the chipless radio frequency identification tags according to the present invention are part of an RFID system that also includes one or more RFID readers, which may or may not be connected to supervisory computers or an electronic board that processes the received information and can, for example, link to existing databases. These readers therefore allow objects to be identified by the RFID tags affixed to them, these chipless RFID tags being comparable to a static radar target with a specific electromagnetic signature. Thus, in a particular embodiment of the present invention, the RFID readers are therefore comparable to a radar in terms of operation, for example, an airborne radar detecting the signature of aircraft, albeit with a difference in scale and power.For example, RFID tags without chips can be viewed as radar targets with a specific temporal or frequency signature. Any type of radar suitable for receiving / identifying the signal back-transmitted by the RFID tag can advantageously be used within the scope of the invention; by way of example, and without limitation, we will mention pulse radar.

[0142] The coding capacities obtained by means of the chipless radio frequency identification tags according to the present invention meet the standards in force because the tags obtained allow for at least 40 bits of information, which corresponds to the EAN13 type barcodes. By way of illustration, values ​​of more than 40 bits for a credit card format [i.e. 40 / (85.60 × 53.98 mm) = 40 / 46 bits / cm2< ] have been obtained; thus, in a particular embodiment according to the present invention, the tags of the strip which is the subject of the present invention are characterized by a coding capacity value greater than 0.85 bits / cm2< , for example greater than 1 bit / cm2< , greater than 2 bits / cm2< , or even greater than 5 bits / cm2< .

[0143] In one embodiment of the present invention, the tag of the strip that is the subject of the present invention can be affixed to any type of object and / or living being (for example, an animal or a human). In one embodiment of the present invention, the object on which the tag will be affixed (preferably glued) can be selected from a large number of materials, including, by way of non-limiting example, metal, paper, fabric, plastic, for example, methacrylic copolymer resin, polyester, polycarbonate, polyethylene, polypropylene, and / or polyvinyl chloride, or even cellulosic-type materials such as, for example, wood, plywood, or crystalline materials such as glass or ceramics, for example, complex materials comprising one or more of these components, such as milk cartons.

[0144] In an embodiment of the present invention and provided that the dielectric substrate of the tag of the strip subject to the present invention meets the requirements of one or more of the aforementioned requirements, said dielectric substrate may be selected from a large number of materials, including by way of non-limiting examples paper, fabric, plastic, for example a methacrylic copolymer resin, polyester, polycarbonate, polyethylene, polypropylene, and / or polyvinyl chloride, or even cellulosic type materials such as, for example, wood, plywood or crystalline materials such as glass or ceramics, for example complex materials comprising one or more of these components such as milk cartons.

[0145] This application describes various technical features and advantages with reference to the Figures and / or various embodiments. Those skilled in the art will understand that the technical features of a given embodiment can in fact be combined with features of another embodiment unless the contrary is explicitly stated, or it is obvious that such features are incompatible, or that the combination does not provide a solution to at least one of the technical problems mentioned in this application. Furthermore, the technical features described in a given embodiment can be isolated from the other features of that embodiment unless the contrary is explicitly stated.

[0146] It should be obvious to those skilled in the art that the present invention allows for embodiments in many other specific forms without departing from the scope of the invention as claimed. Therefore, the present embodiments should be considered illustrative, but may be modified within the scope defined by the attached claims, and the invention should not be limited to the details given above.

Claims

1. A chipless radio frequency identification label strip, said strip comprising a dielectric substrate layer and patterned conductive material layers representing label resonators, said strip has dimensions of length L, width l and thickness Ep and is characterised in that it comprises V-shaped grooves of depth Pr of the strip and oriented in the direction of the width of the strip.

2. Chipless radio frequency identification label strip according to claim 1, characterised in that the depth of the grooves is such that Pr > 1% of the thickness Ep of the strip, for example Pr > 5% of the thickness Ep of the strip.

3. Chipless radio frequency identification label strip according to any one of the preceding claims, characterised in that the depth Pr of the grooves is such that Pr < 90% of the thickness Ep of the strip, for example Pr < 50% of the thickness Ep of the strip.

4. Chipless radio frequency identification label strip according to any one of the preceding claims, characterised in that the length of the grooves is greater than 80% of the width l of the strip, for example greater than 90% of the width l of the strip, preferably identical to the width l of the strip.

5. Chipless radio frequency identification label strip according to any one of the preceding claims, characterised in that the grooves are on both sides of the strip.

6. Reel of chipless radio frequency identification label strip, said strip being characterised by any one of the preceding claims.

7. Reel according to claim 6, characterised in that it comprises a central cylindrical support element for winding the strip, for example a mandrel.

8. Reel according to claim 7, characterised in that the diameter of the central cylindrical support element "Dia" is between 25 mm and 305 mm.

9. Reel according to any one of claims 7 and 8, characterised in that the diameter of the reel "Dreal" is between 50 mm and 1000 mm.

10. Reel according to any one of claims 8 and 9, characterised in that the spacing between two consecutive grooves "Esp" satisfies Esp / 2 2 + Dia / 2 2 1 / 2 − Dia / 2 < 2 mm And / or Esp / 2 2 + Dreal / 2 2 1 / 2 − Dreal / 2 < 2 mm11. Reel according to any one of claims 8 and 9, characterised in that the spacing between two consecutive grooves "Esp" satisfies Esp / 2 2 + Dia / 2 2 1 / 2 − Dia / 2 < 1 mm And / or Esp / 2 2 + Dreal / 2 2 1 / 2 − Dreal / 2 < 1 mm12. Strip or reel according to any one of the preceding claims, characterised in that the distance between the grooves and the resonators and / or resonator patterns is greater than 1 mm.

13. Strip or reel according to the preceding claim, characterised in that the distance between the grooves and the resonators and / or resonator patterns is greater than 2 mm.

14. Strip or reel according to any one of the preceding claims, characterised in that the thickness of the dielectric substrate is greater than 0.1 mm.

15. Strip or reel according to any one of the preceding claims, characterised in that the thickness of the dielectric substrate is less than 5 mm.

16. Strip or reel according to any one of the preceding claims, characterised in that the dielectric substrate is selected from dielectric substrates having at least one, two or all three of the following properties: • an apparent density of less than 250 kg.m-3 ; • a relative permittivity of less than 1.25 and greater than 1.01; • a loss tangent value of less than 10-3.

17. Strip or reel according to the previous claim, characterised in that the dielectric substrate has an apparent density between 25 and 75 kg.m-3 ; a relative permittivity between 1.05 and 1.09; and a loss tangent value tan δ between 10-5 and 2.10-4 at a frequency of 3.9 GHz.

18. Strip or reel according to any one of the preceding claims, characterised in that the thickness of the conductive layer constituting the pattern is less than 10 microns.

19. Strip or reel according to any one of the preceding claims, characterised in that the strip comprises a conductive layer on the face of the dielectric substrate layer opposite to that comprising the patterns consisting of a layer of conductive material.

20. Method for preparing the strip of chipless radio frequency identification labels and / or its corresponding reel according to any one of the preceding claims by means of a roll-to-roll process that incorporates a cutting station for making the grooves.