Chipless Radio Frequency Identification (RFID) Tag Strip

Abstract

Chipless Radio Frequency Identification (RFID) Tag Strip The present invention relates to a chipless (customizable) RFID tag strip, also called a "chip-less RFID tag" strip. More particularly, the present invention relates to a reel of chipless (customizable) RFID 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 l, and thickness Ep, and in that it comprises grooves of depth Pr in the strip oriented in the direction of the strip's width. The present invention also relates to a method for preparing a chipless (customizable) RFID tag strip and its corresponding reel. Figure for the abstract: Fig. 2

Description

Title of Invention: Chipless Radio Frequency Identification ("RFID") Tag Strip

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

[0002] These labels will advantageously be included in chipless (personalized) radio frequency identification devices (called "RFID", with "RF" designating radio frequency); by "device" is meant a package, a document, in particular a security document as well as possibly any object comprising a portion of the strip comprising at least one chipless RFID label.

[0003] Data transmission systems using radio frequency identification technology are commonly used to identify all types of objects and living beings (e.g. an animal or a human) carrying a suitable device (tag). RFID technology has become increasingly widespread in recent 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 placed on an object, and a reader, also called an interrogator, to read and identify the radio tag. RFID technologies are generally classified into categories using "active" or "passive" radio tags. Active radio tags have a local energy source (such as a battery) through which they send a signal to the reader; they are thus generally characterized by a relatively long transmitted signal range.On the other hand, 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 lower signal range, generally less than 8 meters.

[0005] From a practical point of view, RFID technology uses radio frequencies ("RF") which have much higher material penetration characteristics than optical signals. Thus, in comparison with barcode labels, RFID technology will allow use in much more hostile environmental conditions; for example, RFID labels can be read through all kinds of material such as paper, cardboard, wood, paint, water, dirt, dust, the animal or human body, concrete or even through the labeled article 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, cars (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 driving license, a lottery ticket, a transport ticket or an entry ticket to cultural or sporting events.

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

[0007] RFID chip tags (active or passive) generally comprise an antenna, an electronic circuit, and a memory for storing an identification code. The electronic circuit makes it possible, in particular, to receive the signal emitted by the reading terminal and to transmit in response, in a determined frequency band, a modulated signal containing the identification code stored in the memory. For passive RFID chip tags, part of the energy carried by the radio waves emitted by the reading terminal is used to electrically power the chip.

[0008] Due to the presence of electronic circuits (such as the RFID chip or the antenna part) in smart RFID tags, these tags have a significant cost price. It is in particular to reduce this cost price that it has been proposed to produce tags without a chip or antenna. This type of chipless RFID tag therefore requires neither an integrated circuit nor discrete electronic components, such as for example a transistor and / or a coil and / or a capacitor and / or an antenna; it is their conductive geometric characteristic which generates a specific behavior, in particular of the resonator type. This resonance characteristic at a given frequency makes it possible to print chipless RFID tags directly on an object at lower costs than traditional RFID tags.

[0009] Among the different families of chipless tags, they can be differentiated by the presence or absence of an RF antenna at the tag. Conventionally, like RF systems, this antenna has the role of recovering part of the EM wave emitted by the reader, converting it into a guided wave at the tag so that it is conducted through a filter which will give the tag code. This filtered signal, and therefore including the identifier ("ID"), will be re-emitted towards the reader, most often with a second antenna which plays the same role as the first but by performing the reverse process. These RFID tags have been used mainly for make a proof of concept of chipless, however in terms of applications they are very limited. The antennas are bulky and lead to significantly increasing the size of the tag. Similarly, the antenna is generally very sensitive to its immediate environment, this can completely mismatch it, meaning that it will no longer be able to convert the radiated wave into a guided wave to power the filter. This results in a loss of efficiency of the tag, in particular a significant reduction in the reading distance when these tags with antenna are positioned on objects. To overcome these problems, chipless RFID tags without antenna, still based on the same principle of information coding, appeared in the 2010s, for illustration purposes in the following publications

[0010] - E. Perret, S. Tedjini, V. Deepu, A. Vena, F. Garet and L. Duvillaret, Patents for invention published with numbers FR2956232 (Bl) and US8556184 (B2); and - VENA, Arnaud, PERRET, Etienne, and TEDJINI, Smail. Chipless RFID based on RF encoding particle: realization, coding and reading System. Elsevier, Ist Edition - August 2, 2016.

[0011] The major difference with the tags that are the subject of the present invention, sometimes called REP (for “RF encoding particle”), is linked to the fact that they do not involve different RF blocks, namely an antenna part, an RF transmission line part, a filter part, but simply resonant RF patterns that make it possible to code the identifier on the basis of the resonance frequencies that they contain. These tags are artificial radar targets designed to reason at specific frequencies and which are compatible with the possibility of encoding an ID but also of finding 1TD of the tag from the acquisition of the signal backscattered by the label.

[0012] Increasing the coding capacity of chipless radio frequency identification tags as well as the manufacturing of these tags and, in particular, the industrial manufacturing of discriminating tags constitute significant challenges in the state of the art. Although chipless RFID technology has a bright future ahead of it, the fact remains that we are still seeking to improve the reading performance of chipless RFID tags. By reading performance we mean the ability of the tag to be read and identified, i.e., for example, the increase in the signal level of the tag (useful signal carrying the tag information) compared to other signals such as measurement noise or signals backscattered by other objects close to the tag.Specific work on the tag itself, and in particular the materials it is made of, is essential to address the issue of reading performance, as well as the manufacturing and cost of these labels. The materials used to make the tags will in fact have a direct impact on the useful signal backscattered by the tag.

[0013] The applicant has thus developed multi-layer chipless RFID labels. responding, among other things, to the issues of coding capacity and reading performance. We will cite as an illustration the chipless RFID tags described and claimed in patent application WO2021 / 165422 A1. The fact remains that their manufacturing process and, more particularly, their industrial manufacturing, remains a significant challenge to which the present invention responds advantageously as explained in the remainder of this description. Statement of the invention

[0014] Thus, the present invention provides a promising solution to this problem by proposing a chip-less (personalized) RFID tag strip, also called a chip-less RFID tag strip and, in particular, a reel of chip-less (personalized) RFID tag strip. The present invention also relates to a method for preparing a chip-less (personalized) RFID tag strip and its corresponding reel.

[0015] 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 which is the subject of the present invention into an industrial roll-to-roll process (also known as reel-to-reel processing or “roll-to-roll processing” in English) while providing numerous other advantages which will be described in the remainder of this description. Bloodletting

[0018] The cuts may be made by any suitable method, for example by means of a half-flesh cut type cutting tool. The cutting tool will be advantageously positioned within the industrial process for preparing the chipless radio frequency identification tag strip.

[0019] The chipless radio frequency identification tag strip according to the present invention therefore comprises grooves of depth Pr and oriented in the direction of the width of the strip; thus, when the strip is prepared or transported, said grooves are made perpendicular to the direction of movement of said strip. The depth Pr of the grooves will advantageously be selected so as to allow the strip to be wound to form a coil without risking tearing the strip and without affecting the integrity and characteristics of the patterns consisting of a layer of conductive material representing the tag resonators. For illustration purposes, the depth of the grooves will be such that Pr>1% of the thickness Ep of the strip, for example Pr>5% of the thickness Ep of the strip. The depth Pr of the grooves will advantageously be such that Pr<90% of the thickness Ep of the strip, for example Pr<50% of the thickness Ep of the strip. The winding of the strip will thus advantageously be carried out on the side of the strip where the dielectric substrate layer has not been grooved.

[0020] The length of the grooves will also advantageously be selected so as to allow the strip to be wound to form a coil without risking tearing the strip and without affecting the integrity and characteristics of the patterns consisting of a layer of conductive material representing the label resonators. By way of illustration, the length of the grooves will be greater than 80% of the width 1 of the strip, for example greater than 90% of the width 1 of the strip, preferably identical to the width 1 of the strip.

[0021] The width of the grooves will also advantageously be selected so as to allow the strip to be wound to form a coil without risking tearing the strip and without affecting the integrity and characteristics of the patterns consisting 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 for generating 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 mode of application according to the present invention, the shape of the grooves may advantageously have a V-shape because this shape opens up other possibilities for winding the strip as explained below in the description.

[0022] Any suitable measuring method may advantageously be used to measure the dimensions of the grooves. By way of illustration, we will cite the use of a profilometer and / or ultrasound and / or a microscope. Alternatively, it will be sufficient to go back to the cutting tool and the conditions in which the grooves were made to obtain the corresponding dimensions of the grooves.

[0023] The positioning of the grooves on the strip will also be advantageously selected so as to allow the strip to be wound to form a coil without risking tearing the strip and without affecting the integrity and characteristics of the patterns consisting of a layer of conductive material representing the label resonators.

[0024] “Esp” is defined in this disclosure as the spacing between two grooves consecutive (the grooves oriented in the direction of the width of the strip; also called 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 on 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:

[0026] ((Esp / 2)2+(Dia / 2)2)1 / 2 - (Dia / 2) < 2 mm

[0027] Preferably, ((Esp / 2)2+(Dia / 2)2)1 / 2 - (Dia / 2) < 1 mm

[0028] For example, ((Esp / 2)2+(Dia / 2)2)1 / 2 - (Dia / 2) < 0.5 mm

[0029] 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 variable diameter during winding is “Dreel”, the spacings between consecutive grooves “Esp” satisfy the following equation:

[0030] ((Esp / 2)2+(Dreal / 2)2)1 / 2 - (Dreal / 2) < 2 mm

[0031] Preferably, ((Esp / 2)2+(Dreal / 2)2)1 / 2 - (Dreal / 2) < 1 mm

[0032] For example, ((Esp / 2)2+(Dreal / 2)2)1 / 2 - (Dreal / 2) < 0.5 mm

[0033] In one embodiment according to the present invention, the grooves are arranged on the face of the strip on the side of the patterns consisting of a layer of conductive material representing the label resonators. Although grooves can be deliberately positioned on certain resonators so as to modify their resonance characteristics, this would require considerable work to reidentify the label which would deviate from any efficient industrial process. Thus, the grooves will advantageously be positioned outside the label resonators so as not to modify their resonance characteristics, for example between two successive resonators in the direction of the length of the strip.In a preferred embodiment according to the present invention, the grooves will be positioned outside the patterns consisting 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 strip. Although the grooves can be positioned at irregular distance intervals on the strip, positioning at regular intervals will be preferred so as to facilitate the industrial manufacturing process of the strips with their grooves.

[0034] In an embodiment according to the present invention, the grooves are arranged on the face of the strip opposite the side of the patterns consisting 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 strip (perpendicular to the direction of movement of said strip when the latter is prepared or transported); on portions of the strips whose positioning in the direction of the length L of the strip 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 transverse virtual image (through the strip) in the direction of the length of the strip; for example, outside the spaces corresponding to the transverse virtual image (through the strip) of the patterns consisting 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 strip. Although the grooves can be positioned at irregular distance intervals on the strip, positioning at regular intervals will be preferred so as to facilitate the industrial manufacturing process of the strips with their grooves.As described above, a V-shape of the grooves will be particularly suitable for this method of execution of grooves arranged on the face of the strip opposite the side of the patterns made up of a layer of conductive material because it will allow the strip to be wound on the side of the grooves.

[0035] In a particular embodiment according to the present invention, grooves such as those defined above may advantageously be arranged on both sides of the strip; in this case, it will be advantageous to avoid the positioning in the direction of the length L of the strip of the grooves located on one side of the strip coinciding with that of the grooves located on the other side of the strip in order to avoid any tearing of said strip.

[0036] In a particular embodiment according to 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 will call "main grooves"; these additional grooves will therefore advantageously be arranged in the direction of the length of the strip. They will also be positioned and sized so as not to affect the integrity and characteristics of the patterns consisting of a layer of conductive material representing the tag resonators.Thus, the additional grooves will advantageously be positioned outside the tag resonators so as not to modify their resonance characteristics, for example between two successive resonators in the direction of the width of the strip and / or outside the patterns consisting of a layer of conductive material representing the tag resonators, or between two tags or groups of tags in the direction of the width of the strip. Their depths and widths and / or their shape will preferably be defined in the same way as those of the main grooves; however, their lengths will rather be selected according to the dimensions of the tags and / or the 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 consisting of a layer of conductive material representing the label resonators, on the opposite face or on both faces of the strip.

[0037] As an illustration according to the attached [Fig.2], we can see 3 examples of a strip of radio frequency identification ("RFID") tags without a chip, in the length direction, comprising grooves / notches. For each example, we can visualize three conductive patterns positioned on the strip. The arrows symbolize the direction of travel of the strip, that is to say the possibility of winding the strips to transform them into reels.

[0038] [Fig.2](a) shows a strip with grooves of the smallest possible width. As specified above, this width will depend on the equipment used for generating said grooves.

[0039] Figures 2(b) and (c) show V-shaped grooves, a shape which opens up other possibilities for winding the strip. Indeed, the grooves shown in [Fig.2](b) make it possible to wind the strip in such a way that the conductive patterns are on the outer face of the winding, whereas [Fig.2](c) where the V-shapes are on the face opposite the patterns makes it possible to wind the strip in such a way that the patterns are on the inner face (mandrel side) of the reel during winding.

[0040] Coil

[0041] The present invention also relates to a reel of chipless radio frequency identification tag strip, said strip comprising a dielectric substrate layer and patterns made of a layer of conductive material representing the tag resonators, characterized in that the strip of the reel 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.

[0042] In a preferred embodiment according to the present invention, all of the aforementioned groove characteristics will also advantageously apply to the strip of the coil which is the subject of the present invention.

[0043] It is therefore the winding of the strip of chipless radio frequency identification labels which forms the coil which is the subject of the present invention. Said coil may advantageously also comprise any element facilitating its manufacture and / or its handling and / or its transport; the weight of the strip preferably representing at least 90% of the total weight of the coil.

[0044] In a preferred embodiment, the reel which is the subject of the present invention comprises a central cylindrical support element around which said strip is wound.

[0045] Any type of central cylindrical support element for winding the strip of chipless radio frequency identification tags which is the subject of the present invention may advantageously be used within the scope of the present invention provided that its characteristics, in combination with the dimensional characteristics of the strips and the aforementioned grooves, allow the strip to be wound onto said element without risking tearing the strip and without affecting the integrity and characteristics of the patterns consisting of a layer of conductive material representing the tag resonators.

[0046] For illustrative purposes, the central cylindrical support element is a mandrel (for example made of metal or cardboard); the present invention nevertheless also covers reels without mandrels in the same way as certain toilet paper rolls.

[0047] As a reminder, “Esp” is defined as the spacing between two consecutive kerfs (kerfs oriented in the direction of the width of the strip; also called main kerfs above).

[0048] “Dia” is defined in this disclosure as the diameter of the support element cy central core (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.

[0049] “Dréel” is defined in this disclosure as the diameter of the tape reel of chipless radio frequency identification tags; this diameter is the diameter of the sum of the central cylindrical support element (for example the mandrel) and the thickness of the strip wound on said support element. Dréel evolves as the strip is wound. Dréel is preferably between 25 mm and 1250 mm, for example after winding between 50 mm and 1000 mm. The ratio between the maximum diameter of the wound reel of the strip divided by the diameter of its mandrel is preferably between 2.5 and 20, for example between 2.5 and 10, for example between 2.5 and 4.

[0050] In order 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).

[0051] In a particular embodiment according to the present invention, the spacings between consecutive grooves “Esp” satisfy the following equation:

[0052] ((Esp / 2)2+(Dia / 2)2)1 / 2 - (Dia / 2) < 2 mm

[0053] Preferably, ((Esp / 2)2+(Dia / 2)2)1 / 2 - (Dia / 2) < 1 mm

[0054] For example, ((Esp / 2)2+(Dia / 2)2)1 / 2 - (Dia / 2) < 0.5 mm

[0055] In a particular embodiment according to the present invention, a mode which takes into account the increase in the actual diameter of the coil as the winding progresses, creating a possibility of gradual increase in the spacing between grooves, the spacings between consecutive grooves “Esp” satisfy the following equation:

[0056] ((Esp / 2)2+(Dreal / 2)2)1 / 2 - (Dreal / 2) < 2 mm

[0057] Preferably, ((Esp / 2)2+(Dreal / 2)2)1 / 2 - (Dreal / 2) < 1 mm

[0058] For example, ((Esp / 2)2+(Dreal / 2)2)1 / 2 - (Dreal / 2) < 0.5 mm

[0059] “Ec” is defined in this disclosure as the deviation at any winding point of the strip between the lower surface of the strip and its winding support (the support element) during the first winding revolution; “EcMAX” being the largest gap. Although the objective of the invention, with its grooves, is to approach a perfect winding which follows the circumference of the mandrel, it is legitimate to accept an EcMAX gap which is greater than 0.01 mm, for example greater than 0.1 mm.

[0060] Preparation of tapes and tape reels

[0061] The present invention also relates to a method for preparing the chipless (personalized) RFID tag strip and its corresponding reel. Any roll-to-roll (or reel-to-reel) method of the prior art ("roll to roll" in English) may advantageously be used within the scope of the present invention provided that it incorporates the requirements relating to the dimensions of the reels and the grooves mentioned above. The method for preparing the chipless radio frequency identification tag strip and / or its corresponding reel according to the present invention will advantageously use a roll-to-roll method which incorporates a cutting station for making the grooves.

[0062] The applicant has found that the present invention makes it possible to maintain in a reproducible manner the coding capabilities and reading performance of the labels thus manufactured in strip / reel with their grooves whereas this was not possible when the grooves were not carried out in accordance with the present invention. Without wishing to be restricted by this explanation, the applicant believes that the maintenance of coding capabilities and reading performance has been made possible thanks to an improved control of the curvature of the strip at critical locations, namely at locations close to the labels and their resonators. Thus, it will be preferable to maintain a minimum distance between the grooves and any resonator; for illustration purposes any groove will be more than 1 mm, or even more than 2 mm, away from any resonator and / or pattern of resonators.

[0063] In a preferred embodiment according to the present invention, all the characteristics mentioned below will also advantageously apply not only to the strip which is the subject of the present invention but also to the strip of the reel which is the subject of the present invention.

[0064] For illustrative purposes, the dielectric substrate layer of the label strip The chipless radio frequency identification material of the present invention may be selected from solid foam, foam board, corrugated board, honeycomb board or fabric (for example a material made of interwoven threads or fibers of cotton, hemp, linen or synthetic materials such as nylon, polyamide or viscose).

[0065] As described in more detail in the following description, solid foam is preferably understood to mean 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 only very little matter in the solid state, the solid state preferably being a state of matter characterized by the absence of freedom between the molecules or the 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.

[0066] This dielectric substrate and conductive pattern assembly according to the present invention makes it possible to obtain labels which not only have optimal resonance characteristics while having superior radiation efficiency and also superior reading performance; thus, it is at least the sum of the two layers, dielectric and conductive pattern, which define the resonance characteristics of the labels of the strip and the reel which are the subject of the present invention. This makes it possible to easily identify the corresponding chipless RFID labels (their RF signature remaining recognizable) while facilitating their manufacture.

[0067] In the context of the present invention, the use of the qualifier “personalized” for the labels simply confirms that the identification / discrimination of said label is possible.

[0068] Dielectric substrate

[0069] The chipless radio frequency identification tag strips according to the present invention are therefore characterized in that they comprise a dielectric substrate layer.

[0070] This dielectric substrate will advantageously be selected from dielectric substrates meeting at least one, two or all three of the following properties:

[0071] • an apparent density of less than 250 kg.m 3 ; for example less than 100 kg.m 3 ; and / or • a relative permittivity of 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 102, preferably in- less than 103, for example less than 2.104.

[0072] By way of illustration, a dielectric substrate will be cited having an apparent density of between 25 and 75 kg.m3; a relative permittivity of between 1.05 and 1.09; and a loss angle tangent value tan δ of between 105 and 2.10 4 at a frequency of 3.9 GHz.

[0073] This particular dielectric substrate will advantageously be selected from dielectric substrates made of solid foam, foam board, corrugated board, honeycomb board or fabric (for example made of a material made of interwoven threads or fibers made of cotton, hemp, linen or synthetic materials such as nylon, polyamide or viscose).

[0074] This dielectric substrate will advantageously be rigid or flexible; it will preferably be in the form of a film.

[0075] The thickness of the dielectric substrate will advantageously be greater than 0.1 mm. This thickness will preferably be greater than 0.5 mm. This thickness will for example be greater than 0.75 mm.

[0076] 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.

[0077] Any dielectric substrate meeting the reading and resonance and discrimination performance objectives according to the present invention may advantageously be used within the scope of the present invention. Illustrative examples include fabric (for example, a material made of interwoven threads or fibers made of cotton, hemp, linen, or synthetic materials such as nylon, polyamide, or viscose), corrugated cardboard, honeycomb cardboard, foam board, solid foam, for example polymers or biopolymers.

[0078] In a particular embodiment according to the present invention, the dielectric substrate is characterized by its apparent density which is less than 250 kg.rm3; for example less than 100 kg.m3. The apparent density can be measured by any appropriate method, for example by weighing. Unless otherwise indicated, the densities are given for bodies at a temperature of 20°C, under normal atmospheric pressure (1013 hPa). It is also advantageous to use any ASTM or ISO method applicable to the type of material selected as dielectric substrate for the measurement of this apparent density; whatever 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.

[0079] In a particular embodiment according to the present invention, the dielectric substrate is characterized by its dielectric properties, namely a permittivity relative permittivity 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 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.

[0080] 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 102, preferably less than 103, for example less than 2.104.

[0081] 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.

[0082] The relative permittivity and loss angle tangent ("tan ô") can be measured by any appropriate method. We will cite as an illustration the use of dielectric spectroscopy or resonant cavities which are generally used dielectric analysis techniques. These techniques are based on the measurement of the complex impedance of a sample at a given frequency or even at a given temperature. The present invention relates to applications for temperatures around room temperature (typically between -20°C and +80°C), in this temperature range, the permittivity as well as the dielectric losses of the dielectric materials commonly present around us can be considered as relatively constant, particularly in the band of interest which is the UWB band between 3GHz and 10GHz.

[0083] This method makes it possible to have access to the value of the permittivity of a material or even to its loss factor tan ô at a given frequency for example. The values ​​indicated in the present description correspond to those measured at any frequency included in the frequency band from 3 GHz to 10 GHz, at a temperature of 20°C. In particular, the values ​​indicated in the examples which follow were measured using the Damaskos model 08 (“Thin Sheet Tester - Cavity”) which makes it possible to obtain an excellent estimate of the dielectric permittivity of dielectric substrates; this Damaskos thin sheet tester also gives the measurement of the loss tangent of the dielectric on the band from 800-4000 MHz in a non-destructive manner which is particularly well suited to our substrates.The measurement is carried out on common vector and scalar analyzers under the control of Damaskos equipment and the data processing of the “Cavity” software sold by the Damaskos company, which offers very good repeatability. Solid foam

[0084] Solid foam (e.g., polymer foam), is a solid foam used for illustrative purposes in many applications such as thermal insulation, acoustic insulation, packaging, automotive, etc. This foam can be likened to a continuous solid network comprising trapped gas bubbles (generally air), which makes it possible to combine the properties of a foam (density, lightness) with those of a solid.

[0085] The solid foam can advantageously be characterized by its nature, its density, its closed or open cell structure, the size of its bubbles and the arrangement of said bubbles in space.

[0086] A solid foam is said to be of low density when it contains more than 90% gas, which corresponds to an apparent density of less than 100 kg.rm3. A medium density foam has an apparent density of between 100 and 600 kg.rm3. Finally, a high density solid foam contains less than 60% gas, which corresponds to an apparent density of more than 600 kg.rm3. The apparent density can be measured by any suitable method, for example by weighing. Unless otherwise indicated, the densities are given for bodies at a temperature of 20°C, under normal atmospheric pressure (1013 hPa).

[0087] The solid foam used in the context of the present invention will preferably have an apparent density of less than 250 kg.m3. For example, it will have an apparent density of less than 100 kg.m3.

[0088] The solid foam used in the context of the present invention will preferably have a bubble density of between 104 and 109 bubbles / cm3. For example, it will have a bubble density of between 105 and 108 bubbles / cm3.

[0089] 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.

[0090] Any material having the foam characteristics defined within the scope of the present invention may advantageously be selected. We will cite by way of illustration foam board, polymers or biopolymers. By polymer we generally understand a set consisting of several macromolecules (molecule consisting of the repetition of numerous subunits); in general, when the molar mass of the material is greater than 2,000 g / mole we speak of polymer.

[0091] In a particular embodiment according to the present invention, the solid foam will 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 mentioned. A foam comprising more than 80% by weight, for example more than 90% by weight of extruded polystyrene, polyethylene (PE) or polyethylene terephthalate (PET) will be advantageously selected in the context of the present invention.

[0092] The morphology of the foams, in particular the size of the bubbles and the bubble density, may be determined by any appropriate method. For example, the foam (e.g., polymer foam) is fractured under liquid nitrogen to position itself below the glass transition temperature of the polymer; as the fracture surface is clean, the bubbles are not deformed and can be observed, for example, by microscopy. An electron microscope coupled with image analysis software capable of counting the number of bubbles will preferably be used; and also of calculating the average bubble diameter for each image, which makes it possible to determine the average bubble diameter, and 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) with n being the number of bubbles in the image and A being the number of bubbles in the image.

[0093] The polymer foam can be prepared by any suitable method. Illustrative examples include physical foaming with gas injection (e.g. CO2 or nitrogen (N2)) or chemical foaming with addition and decomposition of a blowing agent (e.g. 5-Phenyltetrazole, p-Toluene sulfonyl semicarbazide, Dinitrospoenta-methylenetetramine, p-Toluene sulfonyl hydrazide, pp-Oxybis(benzene)sulfonyl hydrazide and / or Azodicabonamide which is preferably used).

[0094] An extrusion blow molding process is particularly suitable for preparing a polymer foam film that can be used in the context of the present invention, in particular a polystyrene foam film in the form of rolls with or without adhesive.

[0095] Nucleating agents can advantageously be added to the polymer, which makes it possible to obtain small bubbles. Illustrative examples include inorganic fillers (for example 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, for example, nanoclays or carbon nanoparticles (for example, nanotubes).

[0096] In a particular embodiment according to the present invention, the solid foam will be selected from foam boards, also called foam boards; this type of material generally consists of two or three layers including a main layer (internal if three layers) of polymer foam (for example polystyrene, polyurethane, polyethylene and / or polyethylene terephthalate (PET)) coated with the exterior of 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 tiny thickness compared to that of the solid foam as explained in detail below. On the other hand, this stack 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).

[0097] Generally, 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 here 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 is itself made up of a dielectric substrate with its characteristics as described here above and one or more thin dielectric layers, for example a thin dielectric layer on which is (are) affixed the pattern(s) made up 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)) therefore advantageously represents less than 5%, or even less than 1% of the thickness of the entire dielectric substrate.

[0098] Although a priori optional and not critical, the Applicant has found that this thin dielectric layer or dielectric film provides numerous additional advantages to the RFID tag which is the subject of the present invention, subject to a few preferred requirements.

[0099] First of all, it is important to mention that the "relative" relative permittivity and loss angle tangent values ​​of the corresponding dielectric stack of the label strip which is the subject of the present invention will always have values ​​corresponding to the characteristic values ​​already cited above; the influence of the additional dielectric film (or films) on the dielectric assembly will therefore be insignificant compared to these criteria.

[0100] Next, and this represents a considerable advantage of an embodiment according to the present invention, the Applicant has noted that the flatness and / or the 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; in fact, 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 good surface condition, the use of an additional dielectric film made it possible to obtain better results / performances because, among other things, it provided this desired flatness and / or surface condition. Thus, by having pattern(s) consisting of a layer of conductive material affixed to this dielectric film, better performances could be obtained. Any appropriate method could be used to characterize this flatness and / or surface condition of the conductive film.By way of illustration, and in order to avoid having to enter into measurement considerations that are difficult to implement, the label strips that are the subject of the present invention will advantageously be characterized by a total thickness at any point of the resonators of the label (see at any point of the label) which varies by less than one hundred (100) microns, preferably by less than fifty (50) microns, for example by less than forty (40) microns, by less than twenty (20) microns, by less than ten (10) microns, or even for example by less than two (2) microns. The affixing of the pattern(s) consisting of a layer of conductive material directly onto this dielectric film may be carried out by any appropriate method as explained below in the description, for example by printing, for example by inkjet printing.Then, the dielectric film covered with the pattern(s) consisting of a layer of conductive material may 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 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.

[0101] In a particular embodiment, the dielectric film is characterized by one, two or more of the following characteristics:

[0102] - a relative permittivity measured at any frequency between 3 and 10 GHz su 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

[0103] - 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 the solid foam); preferably a loss angle tangent value less than 2.10 2 ; and / or

[0104] - 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 of less than 100 microns, for example less than 50 microns; and / or

[0105] - made of plastic material, for example polyethylene, polypropylene or of polyethylene terephthalate.

[0106] In a particular embodiment, the main chemical composition of the dielectric film is identical to that of the main dielectric substrate. For illustration purposes, if the main dielectric substrate is a polyethylene terephthalate foam, the additional dielectric film will also be based on polyethylene terephthalate. Cardboard

[0107] As indicated above, the dielectric substrate according to the present invention may, for illustration purposes, be selected from corrugated cardboard or honeycomb cardboard. For illustration purposes, the corrugated cardboard will be selected from B-flute cardboard (also called PC, generally with a thickness of between 2.5 and 3.5 mm), E-flute cardboard (also called micro-flute, generally with a thickness of between 2 and 1.5 mm); F-flute cardboard (also called Minimicro, generally with a thickness of approximately 1.2 mm), G or N-flute cardboard (called Nanoflute) with a thickness of approximately 0.8 mm, O-flute cardboard, with a thickness of approximately 0.5 mm, or a mixture of two or more of the aforementioned cardboards.

[0108] 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.

[0109] In a particular embodiment according to the present invention, the chipless RFID tag strip comprising a dielectric substrate and one or more patterns consisting of a layer of conductive material is characterized in that the upper part of the dielectric substrate is in contact with the pattern(s) consisting of a layer of conductive material. 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); by way of illustration, no glue is used between these two parts of the tag.

[0110] Conductive layer

[0111] Chipless radio frequency identification tag strips (tags RFID without chip) according to the present invention are therefore characterized in that they comprise a dielectric substrate and patterns consisting of a layer of conductive material. In a particular case specific to the present invention, the strips also comprise under the dielectric substrate one or more layers of conductive material; preferably under the entire surface of the dielectric substrate. The configuration comprising two conductive layers, one under the dielectric substrate and that of 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 the tags with ground plane.

[0112] 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 chosen from the group consisting of graphite, copper, nickel, silver, aluminum, platinum and / or mixtures thereof, preferably copper and / or silver and / or aluminum.

[0113] In a particular embodiment according to 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 will be used. For example, a thickness of more than 200 nm will be used. For example, a thickness of more than 250 nm will be used. For example, a thickness of more than 300 nm will be used. For example, a thickness of more than 400 nm will be used. For example, a thickness of more than 500 nm will be used.

[0114] In a particular embodiment according to the present invention, the conductive layer constituting the pattern is characterized by a thickness of conductive material less than 20 microns. The thickness of conductive material will preferably be less than 10 microns, or even less than 2 microns. For example, a thickness of less than 1.5 microns will be used. For example, a thickness of less than 1 micron will be used.

[0115] For illustrative purposes, the layer of conductive material may be deposited, preferably directly onto the dielectric substrate or onto the optional dielectric film, by any suitable deposition method.

[0116] 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 reel-to-reel printing machine, along a transport path oriented along a longitudinal axis from at least one reel for unwinding the film to at least one reel for winding the printed and / or personalized film, and therefore covered with the patterns of conductive material in accordance with the present invention.

[0117] As an illustration, a conductive ink printing method, in particular a digital conductive ink printing method, more particularly a digital conductive ink printing method using on-demand inkjet, will be cited as a suitable method for manufacturing the tag. This on-demand conductive ink printing preferably uses piezoelectric print heads.

[0118] 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 which comprises a step of digitally printing a first pattern consisting of a printing product, preferably dielectric, such as an ink, a varnish and / or a toner, followed by a step of depositing by superposition 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 as a suitable method for the step of printing the first pattern any digital printing method, more particularly a digital printing method by jet on demand. This jet on demand printing preferably uses piezoelectric print heads.By way of illustration, 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.

[0119] 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.

[0120] We will also cite by way of illustration as an appropriate and preferred alternative method for producing the tag strip the method of successively assembling films / layers together. In this example, the manufacture of the conductive film constituting the patterns representing the tag resonators can either be carried out by printing as described above, or by chemical treatment as described below.

[0121] By way of illustration and diagram, the strip which is the subject of the present invention may advantageously be produced in the following manner: a coil of conductive film is manufactured or purchased comprising a dielectric film (corresponding to that described as optional above), an optional film of glue, and a film of conductive material. For example, a coil of metal layer (represented in the illustrations below by the example of aluminum) ALU / PET is produced with glue:

[0122] --------ALU--------with an illustrative thickness of 5 to 20 pm (test at 6 pm) -------Glue--------(optional) --------PET--------

[0123] 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.

[0124] Then a protective varnish is deposited so as to form the design of the tag on the aluminum face (the varnish only protects the aluminum useful for the tag).

[0125] Then 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 which is not protected by the varnish.

[0126] Then the layers will have to be assembled. In the example below, the dielectric substrate layer is represented by the foam, and the case "with ground plane" has been illustrated. This assembly will therefore be carried out in an illustrative manner by the reel-to-reel process as previously indicated.

[0127] An illustration of the successive corresponding layers is shown below:

[0128] -----VARNISH------representing the tag --------ALU--------representing the tag with a thickness of 5 to 20 pm -------Glue--------(optional) --------PET-------- -------Glue--------(optional) -- MOUSSE -- -------Glue--------(optional) --------PET--------(optional) --------ALU--------(representing the ground plane)

[0129] Thus, and this constitutes a preferred embodiment according to the present invention, the strip of the RFID tag without chip will be constituted successively from bottom to top

[0130] - of an optional but preferred conductive layer, - topped with an optional but preferred dielectric film, - topped with the main dielectric substrate (e.g. solid foam, foam board, corrugated board, honeycomb board and / or fabric, preferably solid foam), - topped with a dielectric film on which is(are) 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.

[0131] The present invention therefore relates to a strip of tags which have resonance characteristics. In a particular embodiment according to the present invention, the tag consists of the dielectric substrates and the conductive layers as described above.

[0132] Tag

[0133] By way of illustration, the chipless (personalized) RFID tag according to the present invention has the following characteristics:

[0134] • A conductive pattern or a set of conductive patterns characterizing its geometry, preferably with at least one or more or all of the asymmetric patterns, • An identifier that includes at least one resonance frequency / r and, preferably, at least one quality factor Q, • 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, • With or without ground plan, and • Polarizing or preferably Depolarizing. Tag - Geometry

[0135] As an example, [Fig.l] shows different geometries of tags with ground plane made specifically within the scope of the present invention. This [Fig.l] illustrates four tags, each having 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 the performance of the tag. The frequency band in which the resonant frequencies of each of the tags are located is indicated at the bottom left of each tag different tag geometries. Tag - Identifier

[0136] The tag according to the present invention will preferably be characterized by an identifier which comprises at least one resonance frequency fr and at least one quality factor Q. Resonant Tag

[0137] 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

[0138] As already explained in the introductory part, our type of chipless radio frequency identification device therefore requires neither integrated circuit nor discrete electronic components, such as for example a transistor and / or a coil. and / or a capacitor and / or an antenna. This type of device is therefore characterized by passive behavior because it will not have to integrate a local energy source (such as a battery).

[0139] The tag can therefore easily characterize a package, a document, a label, in particular a security document as well as possibly any object and / or living being on which the marking of the identification by RFID without chip can be carried out or on which a marking support can be attached. Tag with or without ground plane

[0140] 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 metal layers (the layer of the conductive pattern surmounting the dielectric substrate and the other conductive layer located under the dielectric substrate).

[0141] Thus, the strip which is the subject of the present invention will advantageously be characterized in that it comprises a conductive layer on the face of the dielectric substrate layer located opposite that comprising the patterns consisting of a layer of conductive material.

[0142] By way of illustration, 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 advantageously be selected from the following thicknesses.

[0143] In a particular embodiment according to the present invention, the conductive layer located under the substrate is characterized by a thickness of conductive material greater than 100 nm. For example, a thickness of more than 150 nm will be used. For example, a thickness of more than 200 nm will be used. For example, a thickness of more than 250 nm will be used. For example, a thickness of more than 300 nm will be used. For example, a thickness of more than 400 nm will be used. For example, a thickness of more than 500 nm will be used.

[0144] In a particular embodiment according to the present invention, the conductive layer located under the substrate is characterized by a thickness of conductive material less than 20 microns, for example less than 10 microns, or even less than 2 microns. For example, a thickness of less than 1.5 microns will be used. For example, a thickness of less than 1 micron will be used.

[0145] In a particular embodiment according to the present invention, the total of the layers (conductive pattern - dielectric - conductive layer) could for example have a thickness of 0.1 to 3 mm.

[0146] Although we speak of a tag with or without a mass plane, in the technique, the term "ground plane" is very often associated with the metal layer (located under the substrate) whose surface preferably corresponds completely to that of the substrate.

[0147] In a particular embodiment according to 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 according to 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.

[0148] The second metal layer (the pattern(s)) will be shaped so as to have a particular geometric shape corresponding to the patterns of the tag (like the patterns shown in [Fig.l]). A tag with a ground plane is therefore a structure comprising two metal layers while its analogue without a ground plane will have a single layer, namely the one where the pattern of the tag is made. A tag with a ground plane has the advantage, once positioned on the ground plane side on an object, of electromagnetically isolating the tag from the object. In this case, the influence of the object on the tag is less compared to a tag without a ground plane.

[0149] It is also noted that a tag with a ground plane is a special case of a tag comprising two metallized layers where the substrate is sandwiched. Indeed, in this preferred configuration, one of the two layers is preferably entirely metallized. However, intermediate tag configurations are possible, for example a tag with ground planes, where on the ground plane side openings (removals of metal zones) are made to achieve a particular behavior. This can, for example, make it possible to create new resonances, or to modify those already present on the first conductive layer. They can also promote the isolation of the different resonators of the second metal layer, thus improving the decoupling of these resonances and therefore having an effect which can improve the reading performance of the tag.

[0150] The layer of conductive material of the ground plane can be deposited, preferably directly on the dielectric substrate, by any suitable deposition method. The deposition methods mentioned above for the deposition of the conductive patterns will already be repeated by way of illustration.

[0151] It is also noted that a chipless tag comprising two conductive layers with the dielectric layer in the middle, for cost reasons, can also be produced 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 with the conductive patterns and / or the ground plane is manufactured, it will be advantageously transferred in one go around the dielectric layer. This is possible by folding it all the way around. The only difference compared to the traditional approach (transferring one by one of the two metallized layers on each of the faces of the dielectric) is the presence of the metallized layer on one or more of the 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 the creation of more complex structures, which, like a resonant cavity with metal walls, will improve the quality factor.Thus, a person skilled in the art is able to take advantage of this structure, which is generally simpler to produce because it requires fewer manufacturing steps. Indeed, this latter approach reduces the number of technological steps: printing a single conductive support, and also gluing a single support.

[0152] In a particular embodiment according to the present invention, the dielectric substrate (with or without a ground plane) will be selected from commercial materials used in thermal insulation or acoustic insulation, the characteristics of which correspond to the characteristics of the present invention; and the desired conductive patterns will be directly affixed to these commercial materials.

[0153] The present invention therefore applies advantageously to both tags without a ground plane and tags with a ground plane. Depolarizing tag

[0154] 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 the incident one (we then speak of cross-polarization reflection or cross polarization in English).

[0155] 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.

[0156] In a particular embodiment according to the present invention, the chipless RFID tag strip with ground plane has a ratio between the lower surface area of ​​the dielectric substrate covered with the layer of conductive material and the total lower surface area of ​​the dielectric substrate greater than 0.9.

[0157] Reader

[0158] By way of illustration, in the context of the present invention, the reader is an electromagnetic wave transmitter-receiver reader; the operating principle of said reader is based on the emission of an electromagnetic signal towards the identification tags which will return the said signal according to their geometry (and for example their own resonance characteristics) and on the capture by the reader of the said reflected signal - thus, the processing of the received signal (in particular through a decoding step) will make it possible to trace the information contained in the label / tag.

[0159] Thus, in general, the chipless radio frequency identification tags according to the present invention are part of an RFID system which also comprises one or more RFID readers which are themselves connected or not to supervision computers or to an electronic card which carries out processing of the information received and which can for example make the link with existing databases. These readers therefore make it possible to identify objects thanks to the RFID tags which are affixed to them, said 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 aerial radar detecting the signature of aircraft to a close scale and power ratio.By way of illustration, chipless RFID tags can be seen as radar targets having a particular time or frequency signature. Any type of radar suitable for receiving / identifying the signal retro-emitted by the RFID tag can advantageously be used within the framework of the invention; by way of illustration and not limitation, we will cite pulsed radar.

[0160] The coding capacities obtained by means of the chipless radio frequency identification labels according to the present invention meet the standards in force because the labels obtained allow for at least 40 bits of information, which corresponds to EAN13 type bar codes. By way of illustration, values ​​of more than 40 bits for a credit card format [i.e. 40 / (85.60 x 53.98 mm) = 40 / 46 bits / cm2 ] have been obtained; thus, in a particular embodiment according to the present invention, the labels 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 bits / cm2, greater than 2 bits / cm2, or even greater than 5 bits / cm2.

[0161] In an alternative embodiment of the present invention, the tag of the strip which is the subject of the present invention may be affixed to any type of object and / or living being (for example an animal or a human). In an alternative embodiment of the present invention, the object on which the tag will be affixed (preferably glued) may be selected from a large number of materials, of which we will cite as non-limiting examples metal, 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, for example, milk cartons.

[0162] In an alternative embodiment of the present invention and provided that the dielectric substrate of the tag of the strip which is the subject of 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 of which we will cite as 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 for example milk cartons.

[0163] The present application describes various technical features and advantages with reference to the Figures and / or to various embodiments. Those skilled in the art will understand that the technical features of a given embodiment may in fact be combined with features of another embodiment unless the opposite is explicitly mentioned or it is obvious that these features are incompatible or that the combination does not provide a solution to at least one of the technical problems mentioned in the present application. In addition, the technical features described in a given embodiment may be isolated from the other features of this embodiment unless the opposite is explicitly mentioned.

[0164] It should be apparent to those skilled in the art that the present invention allows embodiments in many other specific forms without departing from the scope of the invention as claimed. Accordingly, the present embodiments should be considered illustrative, but may be modified within the scope defined by the scope of the appended claims, and the invention should not be limited to the details given above.

Claims

Claims

1. 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.

2. A chipless radio frequency identification tag strip according to claim 1 characterized 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. A chipless radio frequency identification tag strip according to any preceding claim, characterized 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. A chipless radio frequency identification tag strip according to any one of the preceding claims, characterized in that the length of the grooves is greater than 80% of the width 1 of the strip, for example greater than 90% of the width 1 of the strip, preferably identical to the width 1 of the strip.

5. A chipless radio frequency identification tag strip according to any preceding claim, characterized in that the grooves are V-shaped.

6. A chipless radio frequency identification tag strip according to any preceding claim, characterized in that the grooves are on both sides of the strip.

7. A reel of chipless radio frequency identification tag strip, said strip being characterized by any one of the preceding claims.

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

9. Coil according to claim 8 characterized in that the diameter of the central cylindrical support element “Dia” is between 25 mm and 305 mm.

10. Coil according to any one of claims 8 and 9 characterized in that the diameter of the “Dréel” coil is between 50 mm and 1000 mm.

11. Coil according to any one of claims 9 and 10 characterized 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 mm

12. Coil according to any one of claims 9 and 10 characterized 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 mm

13. Tape or reel according to any one of the preceding claims, characterized in that the distance between the grooves and the resonators and / or resonator patterns is greater than 1 mm.

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

15. Tape or coil according to any one of the preceding claims characterized in that the thickness of the dielectric substrate is greater than 0.1 mm.

16. Tape or coil according to any one of the preceding claims characterized in that the thickness of the dielectric substrate is less than 5 mm.

17. Tape or reel according to any one of the preceding claims, characterized in that the dielectric substrate is selected from dielectric substrates meeting at least one, two or all three of the following properties: • an apparent density of less than 250 kg.nr3; • a relative permittivity of less than 1.25 and greater than 1.01; • a loss angle tangent value of less than 103.

18. Strip or coil according to the preceding claim, characterized in that the dielectric substrate has an apparent density of between 25 and 75 kg.m 3; a relative permittivity of between 1.05 and 1.09; and a loss angle tangent value tan ô between 10 5 and 2.10 4 at a frequency of 3.9 GHz.

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

20. Tape or coil according to any one of the preceding claims characterized in that the tape comprises a conductive layer on the face of the dielectric substrate layer located opposite that comprising the patterns consisting of a layer of conductive material.

21. A method of preparing the chipless radio frequency identification tag strip and / or its corresponding reel according to any one of the preceding claims by means of a roll-to-roll process which incorporates a cutting station for making the grooves.

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