FR2899360A1 - Inductor for e.g. support, has conductors distributed over surface and connected with each other by connection conductors for forming circuit strands whose ends are connected to power supply circulating electric current in conductors - Google Patents

Abstract

The inductor has conductors (100 - 109), parallel, mutually equidistant and distributed over a surface (120). The conductors are connected with each other by connection conductors (130) to form strands of an electric circuit. Ends of the strands are connected to an electric power supply (140) that circulates an electric current in the conductors. The conductors are incorporated in a plane non conductive base (150) on which articles (160) are placed. The articles have electronic tags (170) whose antenna is in a plane forming an angle less than or equal to 45 degrees with the conductors` axis. An independent claim is also included for a device chosen among a support, a vane, a cash register and a base station and comprising an indicator.

Description

CONDUCTIVE PRODUCT COMPRISING AN ELECTRONIC LABEL, METHOD AND

  The present invention relates to a conductive product comprising an electronic tag, a method and a device for identifying such products. It applies, in particular, to the remote identification of metallized blisters by implementing a radiofrequency identification, known as RFID (acronym for Radio Frequency IDentification). The remote identification by electromagnetic waves uses a reader, also called base station and an electronic tag, also called transponder or tag, associated with each product to be identified. Each electronic tag retains an identification code, generally unique, for example consisting of 64 binary data, forming a code whose structure and meaning are standardized. To read an electronic tag, the base station transmits a modulated electromagnetic field to carry an interrogation signal and, optionally, to power the electronic tags. Upon receipt of this interrogation signal, each electronic tag determines whether it must respond and what it must respond. For example, only electronic tags whose identification code begins with data indicated, explicitly or implicitly, by the base station, must respond and they must respond by providing one or more data of their identification code. In other examples, an anti-collision protocol is used in which each electronic tag determines, for example randomly, when to respond, in order to reduce the risk of two electronic tags responding simultaneously, causing interference. their response signals and hindering the good reception of these signals by the base station. As is readily understood, the presence of conductive parts, for example metal parts or films or having a high proportion of water, disturbs the electromagnetic fields used and limits or even prohibits communication between the base station and the tags. e. The present invention aims to remedy these disadvantages.

  For this purpose, the present invention aims, in a first aspect, a product comprising a metal part substantially flat at least locally, characterized in that it comprises an electronic tag whose antenna is positioned near said metal part, axis of said antenna being parallel to the local plane of said metal part. Thanks to each of these arrangements, the magnetic field parallel to the plane of the metal part can be picked up by the antenna of the electronic tag. Each electronic tag can thus be read, even when several similar products are stacked.

  According to particular features, the antenna of said electronic tag is positioned near and parallel to an edge of said metal piece. Thanks to these provisions, the disturbances due to the presence of the metal part are reduced at the level of the electronic tag. According to particular features, said metal part is a metal blister film. Thanks to these provisions, small blisters can nevertheless be equipped with a virtually invisible electronic tag. According to particular features, the product as briefly described above comprises a channel formed in a non-conductive material, parallel and close to an edge of said metal part, the antenna of said electronic tag being positioned in said channel . Thanks to these provisions, the electronic tag can be easily automatically deposited in the blister at the same time as the content elements, for example tablets or capsules, preserved by the blister are deposited.

  According to particular features, said electronic tag comprises: a core of electrical insulating material having a relative magnetic permeability greater than fifty, a winding surrounding said core, winding forming an antenna adapted to receive an interrogation signal from a base station, - a memory retaining an identification code and - processing means adapted to process the interrogation signal from the base station, to determine whether the electronic tag must respond and, if so, controlling the transmission of a signal by said antenna. Thanks to these arrangements, the sensitivity of the antenna is multiplied as a function of the relative magnetic permeability of the material constituting the core, a value which may exceed 250 or even 650, for a ferrite core, with respect to the same nucleus-free antenna. ferrite.

  According to particular features, said core comprises a ferrite. Thanks to these provisions, the sensitivity gain can be very high, the ferrites having very high magnetic permeabilities. According to particular characteristics, the winding wire is heat-adherent.

  Thanks to these provisions, the winding is easy to achieve. According to particular characteristics, said label is passive. Thanks to these provisions, are cost, its size and weight can be reduced and its life can be increased. According to a second aspect, the present invention aims at a device for identifying at least one product as succinctly described above, produced having a substantially flat metal part, characterized in that it comprises a transmitting antenna adapted to generate magnetic field lines parallel to the axis of said antenna of the electronic tag. Thanks to these provisions, the products can be identified in a large volume.

  According to particular features, the device as briefly described above comprises a means of presentation for presenting a product at a time facing said transmitting antenna so that the plane of said metal part is perpendicular to the main plane of said antenna and that the core of the electronic tag carried by said product is substantially parallel to the field lines generated by said transmitting antenna. According to particular features, the device as briefly described above comprises a means of presentation for presenting a plurality of products constituting at least one stack facing said transmitting antenna in such a way that the plane of each metal part is perpendicular to the plane primary of said transmitting antenna and that the cores of electronic tags carried by said products are substantially parallel to the field lines generated by said transmitting antenna. According to particular features, said presentation means is a conveyor. Thanks to each of these provisions, the products can be identified in piles.

  According to a third aspect, the present invention relates to a method for identifying at least one product comprising a substantially flat metal part, characterized in that it comprises: a step of mechanical association with said product of an electronic label whose antenna is perpendicular to the plane of said mechanical part and a step of positioning said product opposite a transmitting antenna of the base station so that the transmitting antenna generates magnetic field lines parallel to the axis of said antenna; the electronic tag.

  Since the advantages, aims and characteristics of this method are similar to those of the device as briefly described above, they are not recalled here. Other advantages, aims and features of the present invention will emerge from the description which follows, made for an explanatory and non-limiting purpose with reference to the appended drawings, in which: FIG. 1 represents, schematically, in plan view, a particular embodiment of an electronic tag object of the present invention, FIG. 2 represents a beam of curves useful for determining a real magnetic permeability as a function of a length and diameter ratio of a ferrite and as a function of an asymptotic magnetic permeability. FIGS. 3A and 3B show, schematically, in top view and in side view, a particular embodiment of a product according to the present invention, FIG. 4 schematically represents a particular embodiment of a device of FIG. FIG. 5 represents, in the form of a logic diagram, steps implemented in a particular embodiment of the method that is the subject of the present invention. FIG. 1 shows a passive electronic tag. 100 comprising: a core 105 of electrical insulating material having a relative magnetic permeability greater than fifty, - a coil 110 surrounding the core 105, winding 110 forming an antenna adapted to receive an interrogation signal from a base station (see FIG. 4), an electronic circuit 115 comprising a memory 120 holding an identification code and processing means 125 adapted to t the interrogation signal from the base station, to determine whether the electronic tag 100 must respond and, if so, to control the transmission of a signal by the antenna 110. The core 105 is, for example, example, cylindrical circular base. Preferably, the core 105 is constituted and comprises a ferrite. Also, in the following description is called ferrite insulation material of high magnetic permeability constituting the core, without this being limiting. The conductive wire forming the winding 110 is, for example, heat-adherent. Thus, the sensitivity of the antenna 110 is multiplied according to the relative magnetic permeability of the material constituting the core, a value that can exceed 250 or even 650, for a ferrite core, compared to the same ferrite-free antenna.

  It is recalled that the sensitivity of a conventional RFID tag made from a coil of N turns of conductive wires, wound on an average surface S, is given by the conventional relation: = V a 3 (1) wNS wNS whereco = 2itf f is the working frequency of the base station. According to the present invention, it increases the sensitivity of the antenna 110 of the electronic tag 100, of miniature dimensions for reasons of space on small products (see FIGS. 3A and 3B), by winding the antenna 110 on a core 105, also called rod, of electrical insulating material having a relative magnetic permeability greater than fifty, preferably a ferrite. Such a material has a magnetic permeability p very much higher than that of non-ferromagnetic metals because this permeability consists of two terms: ù POPr (2) where po is the magnetic permeability of the vacuum 4 7C 10- 'and where pr is the permeability relative magnetic material, which takes values that can reach several hundred (typically 250 or 550). A ferrite also has the characteristics of an electrical insulating medium since the electrical conductivity of a ferrite is zero.

  The lines of. magnetic field are thus focused in the ferrite core, as if the surface of the ferrite core was multiplied by the relative magnetic permeability pr. Thus, the magnetic field is guided by the ferrite core. The antenna or inductor of the base station (see FIG. 4) can be defined by the radius of its supposedly circular antenna R1, and by the number of turns of the antenna of the base station N1.

  In ferrite present surrounded by a coil of radius R2 having a number of turns N2, placed at a distance D from the antenna of the base station, the mutual coupling inductance M21 or M12 between the two antennas is given by the following relation: PoPrIrR12R2 2N] N2 M12 _ ù 3

  (D2 + R12) 2 Thus, the mutual coupling inductance between the two coils is, due to the presence of the core 105, multiplied by the relative magnetic permeability pr. The surface of an antenna is a function of the geometrical parameters of the label: S = 71- (3D2 - 3D N +2 + N2 (4) 12 b b2 with N: number of turns b: thickness of the coil (b: diameter of the wire used to make the coil The inductance of a coreless coil is given by the relation below to within 5%: a2N2 L =, uo ff F 'F "b + c + R F' = 10b + 12c + 2R 10b + 10c + 1.4RF "= 0.51og 100 + -14R 2b + 3c) where R is the outer radius of the coil b its thickness has the mean radius c is the inner radius For a long coil, F and F "are substantially equal to 1. When the antenna is formed of a coil on a core of insulating material of relative magnetic permeability pr, of diameter D, and length L2, is wound on a length L ,, n The outer diameter of the turns is called D 2. The winding surface is A.

  We can then write: A = 7z-D22 4 Rm = k n2 n2, uA L = ù = R ,,, L, In the embodiment tested by the inventors, the wire used is of thermo-adhesive nature, 51/62 pm type (51 pm 62 pm copper-sheathed diameter) or 20/25 pm.

  The number of turns is the product of the number of turns per layer by the number of layers. For a wire of diameter of sheath d, the number of wire layer is equal to L / d. The number of turns per layer is equal to (D2-D,) / (2d). In practice, all the parameters are connected to each other and are not independent. The reluctance Rm and the magnetic permeability p are therefore difficult to measure. For a very permeable core 105 of length L2 immersed in a magnetic field, the field lines will pass into this core 105 if the path in the air is equal to the length of the core 105. All the field lines whose distance to at the core axis 105 is less than L2 / 2 will pass through the core 105. This can also be expressed by the equivalent area of a ferrite antenna of diameter D and length L is best equivalent to L / D times the The actual magnetic permeability p strongly depends on the ratio between the length of the core 105, the diameter of the core 105 and the relative magnetic permeability of the core 105. The value of Jr communicated by the manufacturer of the core, for example ferrite, is the asymptotic Nasymptotic value for a very long ferrite whose length tends to infinity.

  In practice, an effective magnetic permeability Petfectif of the nucleus 105 can be calculated after defining the length of the core 105, its diameter and the permeability corresponding to the asymptotic value pasymptotic. The network of curves illustrated in FIG. 2 makes it possible to quickly estimate the effective value of 1.4, knowing I and d. The example marked by perpendicular arrows shows the transition from the asymptotic pasticptymptotic ferromagnetic permeability to the effective magnetic permeability Peffective for a ratio I / d of 10. It is also possible to calculate the effective magnetic permeability IJeffective by measuring the inductance of a coil made on a ferrite core and measure or calculate the inductance of an identical coil made without a ferrite core. The ratio gives directly the value of the magnetic permeability p. For example, for a long coil with and without ferrite whose characteristics are given below: The length b of the winding is 7 mm. The outer diameter of the turns is 1.7 mm. and the radius R is 0.85 mm.

  The internal diameter is 1 mm. The wire used has a diameter of 22 μm. Finally the coil has 1,800 turns. To calculate the inductance in the air, it is determined that the internal diameter is equal to the difference between a û c / 2, where c is equal to the difference of the outer radius and the inner radius. So c is 175 pm And a is 325 pm. The number of layers of copper wire is 6 and the number of layers is 300. These figures are compatible with a number of turns equal to 1800.

  The inductance of the coreless coil is approximately 172 pH. The inventors measured an inductance of the coil with ferrite core and found a value of 16 mH.

  It can therefore be estimated that for this coil made on ferrite 8 mm in length, the effective magnetic permeability Peffective is close to 93. The magnetic permeability Nasymptote given by the manufacturer is close to 650. The sensitivity of a non-core electronic tag can be evaluated at around 3.6 mT. In practice, we observed a value close to 500 NT. The gain of the antenna with a ferrite core is thus very close to 7 and confirms the interest of the implementation of the present invention. It is observed that the weight of an antenna made on ferrite can, in the current state of commercial offers, down to 35 milligrams.

  FIGS. 3A and 3B show a product 300 comprising a metal part 305 and an electronic label 310. When it is desired to associate an electronic label with a metal part, for example the metal film of a blister, the latter , placed perpendicularly to the transmitting antenna of a base station, disables the tuning of this transmitting antenna and behaves like a loss generator which attenuates the electric current supplying the electronic tag. An electronic tag placed flat on a blister can be read at a short distance but it is utopian to read a stack of blisters marked in this way. According to one aspect of the present invention, the electronic tag 310 is similar to the electronic tag 100 detailed with reference to FIG. 1. Preferably, the antenna of the electronic tag 310 is positioned near and parallel to an edge. 315 of the metal part 305. In the embodiment described and shown, the metal part 305 is a metal blister film further comprising a film of insulating material, generally a heat-formed plastic material, the metal film and the film of insulating material enclosing a content, for example drugs. The product 300 then consists of this blister and, optionally, its non-metallic packaging, for example cardboard or plastic. The blisters are, very summarily, equivalent to a metal plate, with, all around the blister, a channel formed in a film of insulating material, usually a thermo-formed plastic material. Thus, the channel is, all around the product, parallel and close to an edge of the metal part consisting of the metal film. Preferably, the antenna of the electronic tag is positioned in this channel. Thanks to the implementation of the present invention, the electronic tag 310 can be read despite the presence of metal parts, even when several similar products are in a stack.

  The second aspect of the present invention thus consists in implementing an electronic tag comprising an antenna of very small dimensions made by winding a core of insulating material with a high relative magnetic permeability, for example a ferrite and, preferably, to position said antenna parallel and near an edge of the metal part. The electronic tag placed in the channel around the blister can mark all types of blisters regardless of their content. The electronic tag can be easily automatically deposited in the blister at the same time as the content elements, for example tablets or capsules, stored in the blister are deposited.

  FIG. 4 shows an identification device 400 of at least one product 300, which comprises a base station 405 and a presentation means 410 for products 300. The base station 405 comprises an emitting antenna 415 having a main plan. For example, the transmitting antenna 415 is flat. According to one aspect of the present invention, the main plane of the transmitting antenna 415 is placed perpendicular to the plane of the metal part 305 and the transmitting antenna 415 is adapted to form magnetic field lines parallel to the antenna core. of the electronic label 310 carried by the product 300. In a first variant, the presentation means 410 is adapted to present a product 310 at a time opposite the transmitting antenna 415 so that the plane of the metal part 305 is perpendicular to the main plane of the transmitting antenna 415 and that the nucleus of the antenna of the electronic tag 310 carried by the product 300 is substantially parallel to the field lines generated by the transmitting antenna 415. In a second variant , the presentation means 410 is adapted to present, at the same time, a plurality of products 300 constituting a stack facing the transmitting antenna 415 of such in such a way that the plane of each metal part 305 is perpendicular to the main plane of the transmitting antenna 415 and that the core of the antenna of the electronic tag 310 carried by each product 300 is substantially parallel to the lines of fields generated by the Transmitting antenna 415. For example, presentation means 415 is a manipulator arm, for example a robotic arm or a conveyor. In the case where the products 300 comprise blisters, they are thus placed perpendicular to the transmitting antenna 415 and therefore creating little disturbance of the field emitted by the transmitting antenna 415. The electronic tag 310 of each product 300 is very small but is fed without difficulty by the transmitting antenna 415 perpendicular to the blisters. A stack of blisters is thus identified without difficulty.

  FIG. 5 shows steps of a method for identifying at least one product comprising a substantially flat metal part. During a mechanical association step 505, the product is associated with the product an electronic tag positioned near and parallel to an edge of said metal part, said electronic tag comprising a core of electrical insulating material having a relative magnetic permeability greater than fifty , a winding surrounding said core, winding forming an antenna adapted to receive an interrogation signal from a base station, a memory retaining an identification code and processing means adapted to process the interrogation signal from the base station, determining whether the electronic tag should respond and, if so, controlling the transmission of a signal by said antenna. When the product is of the blister type, during step 505, the electronic label is automatically deposited in the channel of the blister at the same time as the content elements, for example tablets or capsules, preserved by the blister are deposited. .

  During a positioning step 510, the product is positioned facing a transmitting antenna so that the main plane of the transmitting antenna is placed perpendicular to the plane of said metal part, and that the core is placed parallel to the lines. magnetic field generated by said transmitting antenna. During a step 515, one reads, with a base station, jointly, according to known, deterministic or anti-collision techniques, the identifications of the electronic tags associated with the products. As explained with reference to FIGS. 1 to 4, this method makes it possible to identify the products despite the presence of a metal part therein, despite the small size imposed on the electronic label and, possibly, despite the presentation of the products by stacks of products.

Claims (13)

  1 - Product (300) comprising a metal part (305) substantially flat at least locally, characterized in that it comprises an electronic tag (100) whose antenna is positioned near said metal part, the axis of said antenna being parallel to the local plane of said metal piece. 2 - Product (300) according to claim 1, characterized in that the antenna (110) of said electronic tag (100) is positioned near and parallel to an edge (315) of said metal piece (305). 3 - Product (300) according to any one of claims 1 or 2, characterized in that said metal part (305) is a metal blister film. 4 - Product (300) according to any one of claims 1 to 3, characterized in that it comprises a channel (310) formed in a non-conductive material, parallel and close to an edge (315) of the said metal part (305), the antenna (110) of said electronic label (100) being positioned in said channel. 5 - Product according to any one of claims 1 to 4, characterized in that said electronic tag comprises: a core (105) of electrical insulating material having a relative magnetic permeability greater than fifty, - a coil (110) surrounding said core , winding forming an antenna adapted to receive an interrogation signal from a base station, a memory (120) retaining an identification code and - processing means (125) adapted to process the signal of interrogation from the base station, to determine whether the electronic tag must respond and, if so, to control the transmission of a signal by said antenna. 6. Product according to claim 5, characterized in that said core (105) comprises a ferrite. 7 - Product according to any one of claims 5 or 6, characterized in that the winding wire (110) is heat-adherent. 8 - Product according to any one of claims 5 to 7, characterized in that said label is passive. 9 - Device (400) for identifying at least one product (300) according to any one of claims 1 to 8, product comprising a metal part (305) substantially flat, characterized in that it comprises an emitting antenna (415) adapted to generate magnetic field lines parallel to the axis of said antenna of the electronic tag. 10 - Device (400) according to claim 9, characterized in that it comprises a means of presentation (410) for presenting a product (300) at a time facing said transmitting antenna so that the plane of said piece metal (305) is perpendicular to the main plane of said transmitting antenna (415) and the core (105) of the electronic tag (100) carried by said product is substantially parallel to the field lines generated by said transmitting antenna. 11 - Device (400) according to claim 9, characterized in that it comprises a means of presentation (410) for presenting a plurality of products (300) constituting at least one stack opposite said transmitting antenna (415) of such so that the plane of each metal part (305) is perpendicular to the main plane of said transmitting antenna and that the cores (105) of the electronic tags (100) carried by said products are substantially parallel to the field lines generated by said transmitting antenna. 12. Device according to claim 10, wherein said presentation means is a conveyor. 13 - Method for identifying at least one product (300) comprising a metal part (305) substantially flat, characterized in that it comprises: - a step (505) of mechanical association with said product of an electronic tag whose antenna is perpendicular to the plane of said mechanical part and a step (510) for positioning said product opposite a transmitting antenna (415) of the base station so that the transmitting antenna generates parallel magnetic field lines to the axis of said antenna of the electronic tag.