WO1998053420A1 - Contactless communication system by induction process between a terminal and different types of portable objects - Google Patents

Contactless communication system by induction process between a terminal and different types of portable objects Download PDF

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Publication number
WO1998053420A1
WO1998053420A1 PCT/FR1998/000967 FR9800967W WO9853420A1 WO 1998053420 A1 WO1998053420 A1 WO 1998053420A1 FR 9800967 W FR9800967 W FR 9800967W WO 9853420 A1 WO9853420 A1 WO 9853420A1
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Prior art keywords
frequency
type
portable
magnetic field
modulated
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PCT/FR1998/000967
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French (fr)
Inventor
Frédéric WEHOWSKI
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Innovatron Industries
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Publication date
Application filed by Innovatron Industries filed Critical Innovatron Industries
Priority to AU77731/98A priority Critical patent/AU7773198A/en
Priority to EP98925716A priority patent/EP0919038A1/en
Publication of WO1998053420A1 publication Critical patent/WO1998053420A1/en

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    • H04B5/48—

Definitions

  • the invention relates to contactless communication between a terminal and a portable object.
  • each user is provided with a portable object of the type "contactless card” or “contactless badge”, which is an object capable of exchanging information with a fixed half-mast by bringing the badge of the latter to so as to allow non-galvanic coupling.
  • the invention relates to the case where the exchange of information subsequent to this coupling is effected by varying a magnetic field produced by an induction coil, a technique known as the "induction process".
  • the terminal comprises a tuned circuit excited by an alternating signal which produces in the surrounding space an alternating magnetic field.
  • the portable object being in this space detects this field thanks to a circuit tuned on the same frequency and returns signals in the direction of the terminal, by modulation of the coupling for example, thus establishing the desired communication dialogue.
  • This induction technology is well known, in particular the very good definition of the area in which there can be information exchange and the very low cost of the communication function, which generally make it preferable to radioelectric coupling, which is more expensive. and more sensitive to variations in range.
  • Patent EP-A-0 565 469 (Innovatron Industries) and the French application 96 15163 of December 10, 1996, in the name of Innovatron Industries, for a "Portable object remotely powered for communication without contact with a terminal" describe systems of exchange of data using this technology.
  • the system of the invention is of the known type comprising portable objects of a first type, portable objects of a second type, and a terminal comprising transceiver means with a communication coil for radiating towards a portable object d a first type an alternating magnetic field at a first frequency, modulated by data to be transmitted to this portable object of the first type, in order to pick up a modulated disturbance of this magnetic field produced in response by this portable object of the first type, for radiate towards a portable object of a second type an alternating magnetic field at a second frequency, different from the first frequency, modulated by data to be transmitted towards this portable object of the second type, and to capture a modulated disturbance of this magnetic field produced - te in response with this portable object of the second type.
  • this system is characterized in that the portable objects of the first type are portable objects essentially lacking their own power supply means and which derive their power from the magnetic field at the first frequency, and the portable objects of the second type are portable objects essentially provided with own supply means which do not require remote supply.
  • the communication coil associated with the transmitter-receiver means of the field at the first frequency and at the second frequency is a common coil associated with a tuning circuit having resonance peaks on both the first and on the second frequency, and which are connected to means for generating signals at the first frequency, on the one hand, and at the second frequency, on the other hand.
  • the transmission power delivered to the second frequency by the transceiver means is significantly lower than that delivered at the first frequency.
  • active badges which can operate at different frequencies, which is a desirable characteristic.
  • active badges which have their own internal power supply, require from the terminal a much lower transmission power than passive badges, for which it is necessary to ensure not only communication but also remote power supply.
  • active badges could be damaged by the strong intensity of the magnetic field at this frequency when it is placed near a terminal also ensuring communication with passive badges.
  • This strong intensity of the magnetic field moreover, could "wake up" the active badges at a great distance from the terminal, which is undesirable since, at this distance, the active badges would be unable to send in response messages that can pick up the terminal, given their distance.
  • Figure 1 is a schematic representation of the various circuits making up the terminal of the invention.
  • FIG. 2 illustrates a series of cr-ronograms of signals noted at the different points ⁇ _ to e_ in FIG. 1.
  • a terminal is generally shown according to the invention, making it possible to ensure communication with active badges, such as those described in the abovementioned EP-A-0 565 469, and passive, remotely powered badges , such as those described in the above-mentioned French application 96 15163, despite different parameters of frequency, power, type of modulation, modulation rate, data rate and / or type of information coding.
  • active badges such as those described in the abovementioned EP-A-0 565 469
  • passive, remotely powered badges such as those described in the above-mentioned French application 96 15163
  • the terminal of the invention essentially comprises two generators 10, 12 operating at different frequencies, for example 6.78 MHz for communication with active badges and 13.56 MHz for communication with passive badges and remote supply of the latter .
  • These frequencies are of course in no way limiting, their particular choice being simply due to the fact that they correspond to values authorized by European standards for these communication and remote supply functions, and that they are in harmonic relationship with one another. Their high values also make it possible to design circuits with coils having few turns, therefore easy and inexpensive to produce.
  • Each of the generators 10, 12 is modulated on a respective input 14, 16 by a common digital signal present on the line 18 (signal ç of the timing diagram of FIG. 2).
  • the generator 10 is amplitude modulated with a rate of 100%
  • the generator 12 is amplitude modulated with a rate of 10%, this in order not to disturb the remote supply at this same frequency.
  • the digital modulation signal e is produced by the same encoder common to the two generators, which could deliver the same bit rate and the same coding to the two generators.
  • the types of modulation are different for the two generators (in amplitude, frequency, phase, etc.), that the bit rates and the codings are different, etc., type of modulation, bit rate and coding toggling with the transmission frequency.
  • the output signal of the generator 10 (modulated signal a of the timing diagram of FIG. 2) and the output signal of the generator 12 (modulated signal b of the timing diagram of FIG. 2), delivered respectively on lines 20 and 22, are then selected alternately by switches 24, 26 operating in opposition, for example static MOS semiconductor switches under the control of a control line 28 (signal d of the timing diagram of FIG. 2).
  • the switched outputs of the generators then lead to respective rejector bandpass filters 30 and 32, then are combined via resistors 34 and 36 at a common point.
  • the resistors 34 and 36 can be chosen for example so as to transmit a much lower power for the generator 10, intended to supply active badges, than for the generator 12, which must ensure both the communication and the remote supply of the badges. passive. This difference in power can be accentuated by a difference in the operating voltages of the two generators.
  • the common point of the resistors 34 and 36 supplies a series assembly consisting of a dipole 38, a capacitor 40 and the induction coil 42 making it possible to radiate a magnetic field from the signals produced by the generators 10 or 12;
  • the dipole 38 has two branches in parallel, one branch with an inductor 44 in series with a capacitor 46, and the other branch formed by a capacitor 48.
  • the structure formed of the components 40 to 48 constitutes in fact a circuit having two resonance peaks, corresponding to the two frequencies of the generators 10 and 12 and thus using, in an advantageous manner.
  • an unswitched tuned circuit comprising two resonance peaks makes it possible to have an assembly which rapidly follows the changes in working frequency, avoiding having to develop a filter switch which would be difficult to achieve, in particular because of the resonance of the transmission coil.
  • the branch formed by the inductor 44 and the capacitor 46 is tuned to the frequency of 6.78 MHz and therefore short-circuits capacitor 48 for transmission at this frequency.
  • the generator load is then constituted by the capacitor 40 in series with the coil 42, and the value of the capacitor 40 is chosen to obtain correct operation at this frequency of 6.78 MHz.
  • the circuit formed by the inductor 44 and the two capacitors 46 and 48 constitutes a capacitive impedance in series with the capacitor 40 and the inductance of the coil 42; the value of capacitor 48 is chosen to obtain correct operation at this frequency of 13.56 MHz.
  • reception circuits have not been described, but they are in themselves conventional. It can simply be indicated that it is possible to switch them at the same rate as the transmission circuits, this - in order to avoid any interference between the two frequencies, which are harmonic in their entirety.
  • the flowcharts in FIG. 2 illustrate the operation of the terminal with the various signals which it is possible to measure, respectively: a: the emission at 6.78 MHz modulated at 100%, intended for active badges, b: l transmission at 13.56 MHz modulated at 10%, intended for passive badges, ç: the digital data used to modulate generators 10 and 12 (in this example, with a common bit rate and type of coding), d: the switching signal ensuring the switching between the two frequencies of 6.78 MHz and 13.56 MHz, for example a signal ensuring a frequency change every the 30 ms, value sufficiently low for the operation in alternating frequencies to be imperceptible by the user, e: the resulting signal, radiated by the coil 42.

Abstract

The invention concerns a system wherein the terminal comprises transmitter/receiver means (10, 12, 24, 26, 30, 38) with a communication coil (42) to radiate towards a first type of portable object an alternating magnetic field at a first modulated frequency, to receive a modulated disturbance produced in response, to radiate towards a second type of portable object an alternating magnetic field at a second modulated frequency, different from the first, and to receive a modulated disturbance produced in response. The first type of portable objects are essentially unequipped with their own power supply and derive their power supply from the magnetic field at the first frequency, whereas the second type of portable objects are essentially provided with their own power supply means not requiring remote power feeding.

Description

Système de communication sans contact par procédé à induction entre une borne et des objets portatifs de types différentsContactless communication system by induction between a terminal and portable objects of different types
L'invention concerne la communication sans contact entre une bor- ne et un objet portatif.The invention relates to contactless communication between a terminal and a portable object.
De tels systèmes d'échange de données sans contact sont bien connus et, parmi les applications de cette technique, on trouve (de façon non limitative) le contrôle d'accès et le télépéage, par exemple pour l'accès et le péage des transports en commun. Dans ce dernier exemple, chaque usager est muni d'un objet portatif du type "carte sans contact" ou "badge sans contact", qui est un objet susceptible d'échanger des informations avec une berne fixe en approchant le badge de cette dernière de manière à permettre un couplage non galvanique. L'invention vise le cas où l'échange d'informations consécutif à ce couplage est opéré en faisant varier un champ magnétique produit par une bobine d'induction, technique connue sous le nom de "procédé par induction". La borne comporte a cet effet un circuit accordé excité par un signal alternatif qui produit dans l'espace environnant un champ magnétique alternatif. L'objet portatif se trouvant dans cet espace détecte ce champ grâce à un circuit accordé sur la même fréquence et renvoie des signaux en direction de la borne, par modulation du couplage par exemple, établissant ainsi le dialogue de communication recherché. Les avantages de cette technologie par induction sont bien connus, notamment la très bonne définition de la zone dans laquelle il peut y avoir échange d'informations et le coût très bas de la fonction communication, qui la font généralement préférer au couplage radioélectrique, plus coûteux et plus sensible aux variations de portée.Such contactless data exchange systems are well known and, among the applications of this technique, there is (without limitation) access control and electronic toll collection, for example for access and tolling of transport. in common. In this last example, each user is provided with a portable object of the type "contactless card" or "contactless badge", which is an object capable of exchanging information with a fixed half-mast by bringing the badge of the latter to so as to allow non-galvanic coupling. The invention relates to the case where the exchange of information subsequent to this coupling is effected by varying a magnetic field produced by an induction coil, a technique known as the "induction process". To this end, the terminal comprises a tuned circuit excited by an alternating signal which produces in the surrounding space an alternating magnetic field. The portable object being in this space detects this field thanks to a circuit tuned on the same frequency and returns signals in the direction of the terminal, by modulation of the coupling for example, thus establishing the desired communication dialogue. The advantages of this induction technology are well known, in particular the very good definition of the area in which there can be information exchange and the very low cost of the communication function, which generally make it preferable to radioelectric coupling, which is more expensive. and more sensitive to variations in range.
Le brevet EP-A-0 565 469 (Innovatron Industries) et la demande rrançaise 96 15163 du 10 décembre 1996, au nom d'Innovatron Industries, pour un " Objet portatif téléalimenté pour la communication sans contact avec une borne" décrivent des systèmes d'échange de données utilisant cette technologie.Patent EP-A-0 565 469 (Innovatron Industries) and the French application 96 15163 of December 10, 1996, in the name of Innovatron Industries, for a "Portable object remotely powered for communication without contact with a terminal" describe systems of exchange of data using this technology.
On connaît divers types de badges sans contact utilisés dans le ca- dre de cette technique, qui fonctionnent à des fréquences diverses, et/ou qui sont du type dit "actif, c'est-à-dire comportant une pile d'alimentation incorporée (comme dans le EP-A-0 565 469 précité) ou bien "passif, c'est-à-dire téléalimentés par de l'énergie magnétique émise par la borne (comme dans la demande française 96 15163 précitée). L'un des buts de la présente invention est de permettre d'utiliser indifféremment, avec une même borne, des badges de types différents, actifs et passifs.Various types of contactless badges are known that are used in the context of this technique, which operate at various frequencies, and / or which are of the so-called "active type, that is to say comprising an incorporated power supply battery (as in the aforementioned EP-A-0 565 469) or else" passive, that is to say remotely powered by the magnetic energy emitted by the terminal (as in the French application 96 15163 cited above). One of the aims of the present invention is to make it possible to use, with the same terminal, badges of different types, active and passive.
Le système de l'invention est du type connu comprenant des objets portatifs d'un premier type, des objets portatifs d'un deuxième type, et une borne comportant des moyens émetteurs-récepteurs avec une bobine de communication pour rayonner vers un objet portatif d'un premier type un champ magnétique alternatif à une première fréquence, modulée par des données à émettre vers cet objet portatif du premier type, pour capter une perturbation modulée de ce champ magnétique produi- te en réponse par cet objet portatif du premier type, pour rayonner vers un objet portatif d'un deuxième type un champ magnétique alternatif à une deuxième fréquence, différente de la première fréquence, modulée par des données à émettre vers cet objet portatif du deuxième type, et pour capter une perturbation modulée de ce champ magnétique produi- te en réponse par cet objet portatif du deuxième type.The system of the invention is of the known type comprising portable objects of a first type, portable objects of a second type, and a terminal comprising transceiver means with a communication coil for radiating towards a portable object d a first type an alternating magnetic field at a first frequency, modulated by data to be transmitted to this portable object of the first type, in order to pick up a modulated disturbance of this magnetic field produced in response by this portable object of the first type, for radiate towards a portable object of a second type an alternating magnetic field at a second frequency, different from the first frequency, modulated by data to be transmitted towards this portable object of the second type, and to capture a modulated disturbance of this magnetic field produced - te in response with this portable object of the second type.
Selon l'invention, ce système est caractérisé en ce que les objets portatifs du premier type sont des objets portatifs essentiellement dépourvus de moyens d'alimentation propre et qui dérivent leur alimentation du champ magnétique à la première fréquence, et les objets por- tatifs du deuxième type sont des objets portatifs essentiellement pourvus de moyens d'alimentation propres ne nécessitant pas de téléalimentation.According to the invention, this system is characterized in that the portable objects of the first type are portable objects essentially lacking their own power supply means and which derive their power from the magnetic field at the first frequency, and the portable objects of the second type are portable objects essentially provided with own supply means which do not require remote supply.
De préférence, la bobine de communication associée aux moyens émetteurs -récepteurs du champ à la première fréquence et à la deuxiè- me fréquence est une bobine commune associée à un circuit d'accord présentant des pics de résonance à la fois sur la première et sur la deuxième fréquence, et qui sont reliés à des moyens de génération de signaux à la première fréquence, d'une part, et à la deuxième fréquence, d'autre part. Avantageusement, la puissance d'émission délivrée à la deuxième fréquence par les moyens émetteurs-récepteurs est notablement inférieure à celle délivrée à la première fréquence.Preferably, the communication coil associated with the transmitter-receiver means of the field at the first frequency and at the second frequency is a common coil associated with a tuning circuit having resonance peaks on both the first and on the second frequency, and which are connected to means for generating signals at the first frequency, on the one hand, and at the second frequency, on the other hand. Advantageously, the transmission power delivered to the second frequency by the transceiver means is significantly lower than that delivered at the first frequency.
Ainsi, on peut disposer d'un système à badges actifs et passifs pouvant fonctionner à des fréquences différentes, ce qui est une caractéris- tique souhaitable. En effet, les badges actifs, qui possèdent leur propre alimentation interne, requièrent de la borne une puissance d'émission très inférieure à celle des badges passifs, pour lesquels il faut assurer non seulement la communication mais aussi la téléalimentation. Si les deux types de badges fonctionnaient à la même fréquence, les badges actifs pourraient être endommagés par la forte intensité du champ magnétique à cette fréquence lorsqu'il serait placé près d'une borne assurant également la communication avec des badges passifs. Cette forte intensité du champ magnétique, en outre, pourrait "réveiller" les badges actifs à grande distance de la borne, ce qui n'est pas souhaitable car, à cette distance, les badges actifs seraient incapables d'émettre en réponse des messages que puisse capter la borne, compte tenu de leur éloignement.Thus, it is possible to have a system of active and passive badges which can operate at different frequencies, which is a desirable characteristic. Indeed, active badges, which have their own internal power supply, require from the terminal a much lower transmission power than passive badges, for which it is necessary to ensure not only communication but also remote power supply. If the two types of badges operated at the same frequency, active badges could be damaged by the strong intensity of the magnetic field at this frequency when it is placed near a terminal also ensuring communication with passive badges. This strong intensity of the magnetic field, moreover, could "wake up" the active badges at a great distance from the terminal, which is undesirable since, at this distance, the active badges would be unable to send in response messages that can pick up the terminal, given their distance.
De cette manière est résolu le problème de la cohabitation entre badges de types différents, en attribuant à chacun sa fréquence propre, par exemple une faible puissance d'émission à 6,78 MHz pour communiquer avec des badges de type actif et une émission à 13,56 MHz pour téléalimenter les badges passifs et communiquer avec ceux-ci, cette émission étant réalisée à une puissance très supérieure.In this way, the problem of cohabitation between badges of different types is resolved, by assigning to each its own frequency, for example a low transmission power at 6.78 MHz for communicating with active type badges and a transmission at 13 , 56 MHz to remotely supply and communicate with passive badges, this transmission being carried out at a much higher power.
De plus, outre les fréquences, pour les deux types de badges les taux de modulation, les débits et le codage utilisé sont différents : ainsi, il est possible d'utiliser une simple modulation d'amplitude à 100 % avec les badges actifs pour l'émission de la borne vers le badge, alors qu'avec les badges passifs le taux de modulation doit être bien inférieur pour ne pas perturber la téléalimentation, puisque l'énergie doit être transmise aux badges passifs de façon continuelle.In addition, in addition to the frequencies, for the two types of badges the modulation rates, bit rates and coding used are different: thus, it is possible to use a simple amplitude modulation at 100% with active badges for the 'transmission from the terminal to the badge, whereas with passive badges the modulation rate must be much lower so as not to disturb the remote power supply, since the energy must be transmitted to passive badges continuously.
D'autres caractéristiques et avantages de l'invention apparaîtront à la lecture d'un exemple détaillé ci-dessous, en référence aux dessins annexes.Other characteristics and advantages of the invention will appear on reading a detailed example below, with reference to the drawings annexes.
La figure 1 est une représentation schématique des divers circuits composant la borne de l'invention.Figure 1 is a schematic representation of the various circuits making up the terminal of the invention.
La figure 2 illustre une série de cr-ronogrammes de signaux relevés aux différents points ε_ à e_ de la figure 1.FIG. 2 illustrates a series of cr-ronograms of signals noted at the different points ε_ to e_ in FIG. 1.
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Sur la figure 1, on a représenté de façon générale une borne selon l'invention, permettant d'assurer indifféremment la communication avec des badges actifs tels que ceux décrits dans le EP-A-0 565 469 précité, et des badges passifs, téléalimentés, tels que ceux décrits dans la demande française 96 15163 précitée, en dépit de paramètres différents de fréquence, de puissance, de type de modulation, de taux de modula- tion, de débit de données et/ou de type de codage des informations.In FIG. 1, a terminal is generally shown according to the invention, making it possible to ensure communication with active badges, such as those described in the abovementioned EP-A-0 565 469, and passive, remotely powered badges , such as those described in the above-mentioned French application 96 15163, despite different parameters of frequency, power, type of modulation, modulation rate, data rate and / or type of information coding.
La borne de l'invention comporte essentiellement deux générateurs 10, 12 fonctionnant à des fréquences différentes, par exemple 6,78 MHz pour la communication avec les badges actifs et 13,56 MHz pour la communication avec les badges passifs et la téléalimentation de ces derniers. Ces fréquences ne sont bien entendu aucunement limitatives, leur choix particulier tenant simplement au fait qu'elles correspondent à des valeurs autorisées par les normes européennes pour ces fonctions de communication et de téléalimentation, et qu'elles sont en rapport harmonique entre elles. Leurs valeurs élevées permettent en outre de concevoir des circuits avec des bobines possédant peu de spires, donc faciles et peu coûteuses à réaliser.The terminal of the invention essentially comprises two generators 10, 12 operating at different frequencies, for example 6.78 MHz for communication with active badges and 13.56 MHz for communication with passive badges and remote supply of the latter . These frequencies are of course in no way limiting, their particular choice being simply due to the fact that they correspond to values authorized by European standards for these communication and remote supply functions, and that they are in harmonic relationship with one another. Their high values also make it possible to design circuits with coils having few turns, therefore easy and inexpensive to produce.
Chacun des générateurs 10, 12 est modulé sur une entrée respective 14, 16 par un signal numérique commun présent sur la ligne 18 (signal ç du chronogramme de la figure 2). Dans cet exemple, le généra- teur 10 est modulé en amplitude avec un taux de 100 %, et le générateur 12 est modulé en amplitude avec un taux de 10%, ceci afin de ne pas perturber la télé alimentation à cette même fréquence. Le signal numérique de modulation e est produit par le même encodeur commun aux deux générateurs, qui pourrait délivrer le même débit et le même codage aux deux générateurs. Il est toutefois préférable que les types de modulation soient différents pour les deux générateurs (en amplitude, en fréquence, en phase, etc.), que les débits et les codages soient différents, etc., type de modulation, débit et codage basculant avec la fréquence d'émission. Le signal de sortie du générateur 10 (signal modulé a du chronogramme de la figure 2) et le signal de sortie du générateur 12 (signal modulé b du chronogramme de la figure 2), délivrés respectivement sur des lignes 20 et 22, sont ensuite sélectionnés en alternance par des commutateurs 24, 26 fonctionnant en opposition, par exemple des com- mutateurs statiques à semiconducteur MOS sous contrôle d'une ligne de commande 28 (signal d du chronogramme de la figure 2). Cette configuration, qui n'est bien entendu pas limitative, permet d'utiliser des générateurs fonctionnant en continu, avec des commutateurs réalisables de façon simple et efficace. En variante, on pourrait cependant prévoir une commande directe, de type "ON/OFF" des générateurs 10 et 12, ou tout autre moyen de sélection approprié.Each of the generators 10, 12 is modulated on a respective input 14, 16 by a common digital signal present on the line 18 (signal ç of the timing diagram of FIG. 2). In this example, the generator 10 is amplitude modulated with a rate of 100%, and the generator 12 is amplitude modulated with a rate of 10%, this in order not to disturb the remote supply at this same frequency. The digital modulation signal e is produced by the same encoder common to the two generators, which could deliver the same bit rate and the same coding to the two generators. However, it is preferable that the types of modulation are different for the two generators (in amplitude, frequency, phase, etc.), that the bit rates and the codings are different, etc., type of modulation, bit rate and coding toggling with the transmission frequency. The output signal of the generator 10 (modulated signal a of the timing diagram of FIG. 2) and the output signal of the generator 12 (modulated signal b of the timing diagram of FIG. 2), delivered respectively on lines 20 and 22, are then selected alternately by switches 24, 26 operating in opposition, for example static MOS semiconductor switches under the control of a control line 28 (signal d of the timing diagram of FIG. 2). This configuration, which is of course not limiting, makes it possible to use generators operating continuously, with switches which can be implemented in a simple and efficient manner. Alternatively, provision could be made for direct control, of the "ON / OFF" type, of the generators 10 and 12, or any other suitable selection means.
Les sorties commutées des générateurs aboutissent ensuite à des filtres passe-bande réjecteurs respectifs 30 et 32, puis sont réunies via des résistances 34 et 36 en un point commun. Les résistances 34 et 36 peuvent être choisies par exemple de manière à transmettre une puissance beaucoup plus faible pour le générateur 10, destiné à alimenter des badges actifs, que pour le générateur 12, qui doit assurer à la fois la communication et la téléalimentation des badges passifs. Cette différence de puissance peut être accentuée par une différence des tensions de fonctionnement des deux générateurs.The switched outputs of the generators then lead to respective rejector bandpass filters 30 and 32, then are combined via resistors 34 and 36 at a common point. The resistors 34 and 36 can be chosen for example so as to transmit a much lower power for the generator 10, intended to supply active badges, than for the generator 12, which must ensure both the communication and the remote supply of the badges. passive. This difference in power can be accentuated by a difference in the operating voltages of the two generators.
Le point commun des résistances 34 et 36 alimente un ensemble série constitué d'un dipôle 38, d'un condensateur 40 et de la bobine d'induction 42 permettant de rayonner un champ magnétique à partir des signaux produits par les générateurs 10 ou 12 ; le dipôle 38 com- porte deux branches en parallèle, dont une branche avec une inductance 44 en série avec un condensateur 46, et l'autre branche formée d'un condensateur 48.The common point of the resistors 34 and 36 supplies a series assembly consisting of a dipole 38, a capacitor 40 and the induction coil 42 making it possible to radiate a magnetic field from the signals produced by the generators 10 or 12; the dipole 38 has two branches in parallel, one branch with an inductor 44 in series with a capacitor 46, and the other branch formed by a capacitor 48.
La structure formée des composants 40 à 48 constitue en fait un circuit présentant deux pics de résonance, correspondant aux deux fré- quences des générateurs 10 et 12 et utilisant ainsi, de façon avantageu- se, une seule et même bobine pour rayonner les champs magnétiques aux deux fréquences ; la cible est ainsi la même quelque soit le type du badge (actif ou passif), et ceci évite également d'avoir à gérer des perturbations éventuelles entre deux bobines voisines. On peut également commuter des éléments, inductance ou capacité, d'un circuit accordé de manière à faire résonner celui-ci à deux fréquences différentes selon la position de commutation. Mais un circuit accordé non commuté comportant deux pics de résonance permet d'avoir un montage qui suit rapidement les changements de fréquence de travail, en évitant d'avoir à mettre au point un commutateur de filtre qui serait délicat à réaliser, notamment à cause de la résonance de la bobine d'émission.The structure formed of the components 40 to 48 constitutes in fact a circuit having two resonance peaks, corresponding to the two frequencies of the generators 10 and 12 and thus using, in an advantageous manner. se, a single coil for radiating magnetic fields at two frequencies; the target is thus the same whatever the type of badge (active or passive), and this also avoids having to manage possible disturbances between two neighboring coils. It is also possible to switch elements, inductance or capacitance, of a tuned circuit so as to make it resonate at two different frequencies according to the switching position. However, an unswitched tuned circuit comprising two resonance peaks makes it possible to have an assembly which rapidly follows the changes in working frequency, avoiding having to develop a filter switch which would be difficult to achieve, in particular because of the resonance of the transmission coil.
Ainsi, la branche formée par l'inductance 44 et le condensateur 46 est accordée sur la fréquence de 6,78 MHz et vient donc court- circui ter condensateur 48 pour une émission à cette fréquence. La charge du générateur est alors constitué par le condensateur 40 en série avec Ja bobine 42, et la valeur du condensateur 40 est choisie pour obtenir un fonctionnement correct à cette fréquence de 6,78 MHz. En revanche, pour une fréquence de 13,56 MHz, le circuit formé par l'inductance 44 et les deux condensateurs 46 et 48 constitue une impédance capacitive en série avec le condensateur 40 et l'inductance de la bobine 42 ; la valeur du condensateur 48 est choisie pour obtenir un fonctionnement correct à cette fréquence de 13,56 MHz.Thus, the branch formed by the inductor 44 and the capacitor 46 is tuned to the frequency of 6.78 MHz and therefore short-circuits capacitor 48 for transmission at this frequency. The generator load is then constituted by the capacitor 40 in series with the coil 42, and the value of the capacitor 40 is chosen to obtain correct operation at this frequency of 6.78 MHz. On the other hand, for a frequency of 13.56 MHz, the circuit formed by the inductor 44 and the two capacitors 46 and 48 constitutes a capacitive impedance in series with the capacitor 40 and the inductance of the coil 42; the value of capacitor 48 is chosen to obtain correct operation at this frequency of 13.56 MHz.
Les circuits de réception n'ont pas été décrits, mais ils sont en eux- mêmes classiques. On peut simplement indiquer qu'il est possible de les comrnuter à la même cadence que les circuits d'émission, ceci --.fin d'éviter toute interférence entre les deux fréquences, qui sont harmoniques enti e elles.The reception circuits have not been described, but they are in themselves conventional. It can simply be indicated that it is possible to switch them at the same rate as the transmission circuits, this - in order to avoid any interference between the two frequencies, which are harmonic in their entirety.
Les organigrammes de la figure 2 illustrent le fonctionnement de ia borne avec les divers signaux qu'il est possible de mesurer, respectivement : a : l'émission à 6,78 MHz modulée à 100 %, destinée aux badges actifs, b : l'émission à 13,56 MHz modulée à 10%, destinée aux badges passifs, ç : les données numériques servant à moduler les générateurs 10 et 12 (dans cet exemple, avec un débit et un type de codage commun), d : le signal de commutation assurant le basculement entre les deux fréquences de 6,78 MHz et 13,56 MHz, par exemple un signal assurant un changement de fréquence tous les 30 ms, valeur suffisam- ment faible pour que le fonctionnement en fréquences alternées soit imperceptible par l'utilisateur, e : le signal résultant, rayonné par la bobine 42. The flowcharts in FIG. 2 illustrate the operation of the terminal with the various signals which it is possible to measure, respectively: a: the emission at 6.78 MHz modulated at 100%, intended for active badges, b: l transmission at 13.56 MHz modulated at 10%, intended for passive badges, ç: the digital data used to modulate generators 10 and 12 (in this example, with a common bit rate and type of coding), d: the switching signal ensuring the switching between the two frequencies of 6.78 MHz and 13.56 MHz, for example a signal ensuring a frequency change every the 30 ms, value sufficiently low for the operation in alternating frequencies to be imperceptible by the user, e: the resulting signal, radiated by the coil 42.

Claims

REVENDICATIONS
1. Un système de communication sans contact entre une borne et des objets portatifs par un procédé à induction, comprenant : — des objets portatifs d'un premier type,1. A contactless communication system between a terminal and portable objects by an induction process, comprising: - portable objects of a first type,
— des objets portatifs d'un deuxième type,- portable objects of a second type,
— une borne comportant des moyens émetteurs-récepteurs (10, 12, 24, 26, 30, 32, 38) avec une bobine de communication (42) pour rayonner vers un objet portatif d'un premier type un champ magnétique alternatif à une première fréquence, modulée par des données à émettre vers cet objet portatif du premier type, pour capter une perturbation modulée de ce champ magnétique produite en réponse par cet objet portatif du premier type, pour rayonner vers un objet portatif d'un deuxième type un champ magnétique alternatif à une deuxième fréquence, différente de la première fréquence, modulée par des données à émettre vers cet objet portatif du deuxième type, et pour capter une perturbation modulée de ce champ magnétique produite en réponse par cet objet portatif du deuxième type, système caractérisé en ce que : — les objets portatifs du premier type sont des objets portatifs essentiellement dépourvus de moyens d'alimentation propre et qui dérivent leur alimentation du champ magnétique à la première fréquence ; et- a terminal comprising transceiver means (10, 12, 24, 26, 30, 32, 38) with a communication coil (42) for radiating an alternating magnetic field to a first object to a portable object frequency, modulated by data to be transmitted to this portable object of the first type, to pick up a modulated disturbance of this magnetic field produced in response by this portable object of the first type, to radiate a magnetic field to a portable object of the second type alternating at a second frequency, different from the first frequency, modulated by data to be transmitted to this portable object of the second type, and for picking up a modulated disturbance of this magnetic field produced in response by this portable object of the second type, system characterized in what: - portable objects of the first type are portable objects essentially devoid of means of own supply and which derive their food tation of the magnetic field at the first frequency; and
— les objets portatifs du deuxième type sont des objets portatifs es- sentiellement pourvus de moyens d'alimentation propres ne nécessitant pas de téléalimentation.The portable objects of the second type are portable objects essentially provided with own supply means which do not require remote supply.
2. Le système de la revendication 1, dans lequel la bobine de communication associée aux moyens émetteurs-récepteurs du champ à la première fréquence et à la deuxième fréquence est une bobine commune (42) associée à un circuit d'accord (38, 40) présentant des pics de résonance à la fois sur la première et sur la deuxième fréquence, et qui sont reliés à des moyens de génération de signaux à la première fréquence, d'une part, et à la deuxième fréquence, d'autre part. 2. The system of claim 1, wherein the communication coil associated with the field transceiver means at the first frequency and the second frequency is a common coil (42) associated with a tuning circuit (38, 40 ) having resonance peaks on both the first and the second frequency, and which are connected to means for generating signals at the first frequency, on the one hand, and at the second frequency, on the other hand.
3. Le système de la revendication 1 ou 2, dans laquelle la puissance d'émission délivrée à la deuxième fréquence par les moyens émetteurs- récepteurs est notablement inférieure à celle délivrée à la première fréquence. 3. The system of claim 1 or 2, wherein the transmission power delivered at the second frequency by the transceiver means is significantly less than that delivered at the first frequency.
PCT/FR1998/000967 1997-05-16 1998-05-15 Contactless communication system by induction process between a terminal and different types of portable objects WO1998053420A1 (en)

Priority Applications (2)

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AU77731/98A AU7773198A (en) 1997-05-16 1998-05-15 Contactless communication system by induction process between a terminal and different types of portable objects
EP98925716A EP0919038A1 (en) 1997-05-16 1998-05-15 Contactless communication system by induction process between a terminal and different types of portable objects

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR97/06022 1997-05-16
FR9706022A FR2763445B1 (en) 1997-05-16 1997-05-16 CONTACTLESS COMMUNICATION TERMINAL, BY MEANS OF AN INDUCTION PROCESS, WITH PORTABLE OBJECTS OF DIFFERENT TYPES

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JP2005218020A (en) * 2004-02-02 2005-08-11 Fujitsu Frontech Ltd Ic card reader

Citations (2)

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US5235326A (en) * 1991-08-15 1993-08-10 Avid Corporation Multi-mode identification system
US5347263A (en) * 1993-02-05 1994-09-13 Gnuco Technology Corporation Electronic identifier apparatus and method utilizing a single chip microcontroller and an antenna coil

Family Cites Families (2)

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Publication number Priority date Publication date Assignee Title
FR2723238B1 (en) * 1994-07-27 1996-09-13 Suisse Electronique Microtech COMMUNICATION SYSTEM BETWEEN A BASE STATION AND A PASSIVE TRANSPONDER
JPH09218263A (en) * 1995-10-11 1997-08-19 Texas Instr Inc <Ti> Transponder system and operating method thereof

Patent Citations (2)

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Publication number Priority date Publication date Assignee Title
US5235326A (en) * 1991-08-15 1993-08-10 Avid Corporation Multi-mode identification system
US5347263A (en) * 1993-02-05 1994-09-13 Gnuco Technology Corporation Electronic identifier apparatus and method utilizing a single chip microcontroller and an antenna coil

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EP0919038A1 (en) 1999-06-02
AU7773198A (en) 1998-12-11
FR2763445A1 (en) 1998-11-20
FR2763445B1 (en) 1999-09-24

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