US20030169169A1 - Antenna generating an electromagnetic field for transponder - Google Patents

Antenna generating an electromagnetic field for transponder Download PDF

Info

Publication number
US20030169169A1
US20030169169A1 US10/344,880 US34488003A US2003169169A1 US 20030169169 A1 US20030169169 A1 US 20030169169A1 US 34488003 A US34488003 A US 34488003A US 2003169169 A1 US2003169169 A1 US 2003169169A1
Authority
US
United States
Prior art keywords
circuit
terminal
antenna
transponder
inductive element
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US10/344,880
Inventor
Luc Wuidart
Michel Bardouillet
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
STMicroelectronics SA
Original Assignee
STMicroelectronics SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from FR0010699A external-priority patent/FR2813149A1/en
Application filed by STMicroelectronics SA filed Critical STMicroelectronics SA
Priority to US10/344,880 priority Critical patent/US20030169169A1/en
Assigned to STMICROELECTRONICS S.A. reassignment STMICROELECTRONICS S.A. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BARDOUILLET, MICHEL, WUIDART, LUC
Publication of US20030169169A1 publication Critical patent/US20030169169A1/en
Priority to US12/560,184 priority patent/US8130159B2/en
Abandoned legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
    • G06K7/10009—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
    • G06K7/10316—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves using at least one antenna particularly designed for interrogating the wireless record carriers
    • G06K7/10346—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves using at least one antenna particularly designed for interrogating the wireless record carriers the antenna being of the far field type, e.g. HF types or dipoles
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/0008—General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
    • G06K7/10009—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
    • G06K7/10158—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves methods and means used by the interrogation device for reliably powering the wireless record carriers using an electromagnetic interrogation field
    • G06K7/10178—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves methods and means used by the interrogation device for reliably powering the wireless record carriers using an electromagnetic interrogation field including auxiliary means for focusing, repeating or boosting the electromagnetic interrogation field
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
    • G06K7/10009—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
    • G06K7/10316—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves using at least one antenna particularly designed for interrogating the wireless record carriers
    • G06K7/10336—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves using at least one antenna particularly designed for interrogating the wireless record carriers the antenna being of the near field type, inductive coil

Definitions

  • the present invention relates to systems using electromagnetic transponders, that is, transmitters and/or receivers (generally mobile) capable of being interrogated in a contactless and wireless manner by a unit (generally fixed), called a read and/or write terminal.
  • transponders extract the power supply required by the electronic circuits included therein from the high-frequency field radiated by an antenna of the read-write terminal.
  • the present invention more specifically relates to a read and/or write terminal for electromagnetic transponders as well as to the antenna that it includes.
  • FIG. 1 very schematically shows a conventional example of a read/write terminal 1 associated with a transponder 10 .
  • terminal 1 is essentially formed of a series oscillating circuit formed of an inductance L1 in series with a capacitor C1 and a resistor R1.
  • This oscillating circuit is controlled by a device 2 including, among others, an amplifier or antenna coupler and a control circuit exploiting the received data provided, in particular, with a modulator/demodulator and a microprocessor for processing the control signals and the data.
  • the oscillating circuit is excited by a voltage Vg provided by device 2 between terminals 3 and 4 .
  • Circuit 2 generally communicates with different input/output circuits (keyboard, screen, means of exchange with a server, etc.) and/or processing circuits, not shown.
  • the circuits of the read/write terminal draw the power necessary to their operation from a supply circuit (not shown) connected, for example, to the electric supply system.
  • a transponder 10 intended for cooperating with a terminal 1 , essentially includes a parallel oscillating circuit.
  • This circuit is formed of an inductance L2 in parallel with a capacitor C2 between two input terminals 11 , 12 of a control and processing circuit 13 .
  • Terminals 11 , 12 are in practice connected to the input of a rectifying means (not shown), the outputs of which form D.C. supply terminals of the circuits internal to transponder 10 .
  • These circuits generally include, essentially, a microprocessor, a memory, a demodulator of the signals that may be received from terminal 1 , and a modulator for transmitting information to the terminal.
  • the oscillating circuits of the terminal and of the transponder are generally tuned on a same frequency corresponding to the frequency of excitation signal Vg of the terminal's oscillating circuit.
  • This high-frequency signal (for example, at 13.56 MHz) is not only used as a carrier of data transmission from the terminal to the transponder, but also as a remote supply carrier for the transponders located in the terminal's field.
  • a transponder 10 is located in the field of a terminal 1 , a high-frequency voltage is generated across terminals 11 and 12 of the transponder's resonant circuit. This voltage, after being rectified and possibly clipped, provides the supply voltage of electronic circuits 13 of the transponder.
  • the high-frequency carrier transmitted by the terminal is generally modulated in amplitude by said terminal according to different coding techniques to transmit data and/or control signals to one or several transponders in the field.
  • the data transmission from the transponder to a terminal is generally performed by modulating the load formed by resonant circuit L2, C2.
  • the load variation is performed at the rate of a sub-carrier having a frequency (for example, 847.5 kHz) smaller than that of the carrier.
  • This load variation can then be detected by the terminal as an amplitude variation or as a phase variation by means, for example, of a measurement of the voltage across capacitor C1 or of current Ig in the oscillating circuit.
  • the measurement signal has been symbolized by a connection 5 in dotted lines connecting the midpoint of the series connection of inductance L1 and capacitor C1 to circuit 2 .
  • a problem which arises in conventional transponder systems is that they generally have a limited range.
  • the system range corresponds to the limiting distance beyond which the field sensed by a transponder is too small to enable extraction of the power necessary for its operation therefrom.
  • the limited range is essentially due to the maximum admissible magnetic field, which is set by standards.
  • the diameter of the antenna is desired to be increased, to avoid exceeding this maximum allowed magnetic field.
  • increasing the diameter amounts to increasing excitation current Ig in proportions that are not desirable, among others, for power consumption reasons.
  • An object of the present invention is to improve the range of electromagnetic transponder read/write terminals.
  • the present invention more specifically aims at providing a novel long-range electromagnetic field generation antenna.
  • the present invention also aims at requiring no modification of the transponders and, accordingly, at being able to operate with any conventional transponder.
  • the present invention also aims at reducing or minimizing the power consumption of the terminal.
  • the present invention provides an antenna for generating an electromagnetic field for an electromagnetic transponder, including a first inductive element intended for being connected to two terminals of application of an excitation voltage, and a parallel resonant circuit coupled with the first inductive element.
  • said resonant circuit includes a second inductive element, the value of which is chosen to be greater than the value of the first inductive element with a ratio depending on a desired field amplification.
  • the first inductive element is formed of several inductances associated in a network.
  • the inductive element(s) are formed of planar windings.
  • the two inductive elements are in parallel planes.
  • the distance that separates the respective planes of the inductive elements is chosen according to the power consumption of the transponders for which the antenna is intended and to the desired range.
  • the present invention also provides a terminal for generating a high-frequency electromagnetic field for at least one transponder entering this field, the terminal including a resonant circuit, magnetically coupled to an excitation circuit including a first inductive element and having no capacitive element.
  • the resonant circuit is formed of a second inductive element and of a capacitive element in parallel, and is tuned to the frequency of an excitation signal of the first inductive element.
  • said resonant circuit includes a control switch.
  • FIG. 1 previously described, shows a conventional example of a transponder system of the type to which the present invention applies;
  • FIG. 2 schematically shows a first embodiment of a read and/or write terminal, provided with an antenna according to the present invention, and associated with a conventional transponder;
  • FIGS. 3A and 3B show an antenna according to a second embodiment of the present invention.
  • FIG. 4 shows an alternative embodiment of a terminal according to the present invention.
  • a feature of the present invention is to provide the antenna of a read and/or write terminal in the form of an LR circuit coupled to a resonant LC circuit.
  • the LR circuit is excited by the high-frequency generator of the terminal.
  • the excitation frequency is, conventionally, that of the remote supply carrier and of the possible data to be transmitted.
  • the resonant circuit forms a rejector circuit formed of an inductance and of a capacitor. It is in practice an RLC circuit with as small a resistance as possible corresponding to the series resistances of the inductance and of the capacitor.
  • Another feature of the present invention is to provide a value of the inductance of the rejector circuit greater than that of the LR excitation circuit.
  • the voltage developed across the capacitor of the rejector circuit is greater than the excitation voltage of the LR circuit.
  • the quality factor of the rejector circuit is desired to be maximized to favor the amplification created by its coupling with the LR excitation circuit.
  • the quality factor is inversely proportional to the sum of the series resistances and to the square root of the capacitance of the rejector circuit, and directly proportional to the square root of its inductance. Accordingly, the inductance is desired to be maximized and the series resistances and the capacitance are desired to be minimized.
  • FIG. 2 very schematically shows a first embodiment of a read and/or write terminal according to the present invention.
  • a terminal 20 includes circuits 2 for processing, controlling, and analyzing data to be exchanged with a transponder 10 , also conventional.
  • a high-frequency voltage Vg used as a remote power supply carrier and/or as a modulation carrier for a transponder is provided across output terminals 3 and 4 of circuit 2 .
  • terminals 3 and 4 are connected to a series LR circuit formed of a resistor R1 in series with an inductance Lp.
  • Inductance Lp is intended to be coupled with an inductance Lb of a rejector circuit 21 associated with the LR circuit.
  • Circuit 21 also includes a capacitor Cb, the two electrodes of which are respectively connected to the two terminals 24 and 25 of inductance Lb.
  • the inductive LR circuit connected across terminals 3 and 4 of circuit 2 , includes no capacitor.
  • this tuning is transferred to rejector circuit 21 .
  • the respective values of inductance Lb and of capacitance Cb are selected so that the resonance frequency of this circuit corresponds to the remote supply carrier of the system (for example, 13.56 MHz).
  • inductances Lp and Lb are, preferably, made in the form of planar inductances having one or several spirals.
  • the inductances are placed in parallel planes to increase or maximize the magnetic coupling between them. This coupling is symbolized in FIG. 2 by mutual inductance M between the LR and LC circuits.
  • Transponder 10 is a conventional transponder, the present invention requiring no modification of the transponder for its implementation. When transponder 10 is present in the terminal's field, it is in magnetic coupling (mutual inductance M′) with the rejector circuit, from which it draws the power necessary to its operation.
  • Inductance Lp is chosen to be as small as possible to optimize the system efficiency and maximize the use of the installed power of the generator providing voltage Vg.
  • the value of inductance Lb of rejector circuit 21 is chosen to be as high as possible to maximize the system range. Indeed, the higher ratio Lb/Lp, the greater the ratio between the voltage developed across capacitor Cb and voltage Vg.
  • the interval between the planar inductances, arranged in parallel planes is adapted to the transponders for which the terminal is intended.
  • the charge level represented by different transponders in particular, according to whether they include or not a microprocessor
  • the coupling between the excitation and rejector circuits can be optimized.
  • the antenna's inductances will be drawn away from each other to maximize the overvoltage generated across the rejector circuit. For example, an interval ranging between approximately 0.5 cm and a few centimeters will be selected.
  • the coupling between inductances must be maximized so that the load represented by the transponders does not alter too much the quality factor of the rejector circuit.
  • the antenna's inductances are then placed as close as possible to each other. The interval of course depends, among others, on the diameter of the inductances and on the quality coefficient of the rejector circuit.
  • An advantage of the present invention is that it enables increasing the range of a read and/or write terminal for a given voltage Vg and excitation current Ig.
  • Another advantage of the present invention is that it requires no modification of existing transponders.
  • the detection of a back modulation coming from a transponder can be performed either on the LR circuit or in LC circuit 21 .
  • a current transformer 22 having the function of measuring the current in rejector circuit 21 has been symbolized.
  • a connection 23 provides the result of this measurement to circuit 2 .
  • the measurement may be performed in the LR circuit. However, it is easier to detect variations in the rejector circuit where the signal levels are higher. It will however be ascertained that this measurement disturbs as little as possible the quality factor of the rejector circuit. For example, if a voltage measurement is performed across capacitor Cb, it will be ascertained to use a measurement element with a high input impedance.
  • the present invention enables increasing the transmitted magnetic field without increasing either the current provided by the generator or voltage Vg, and thus without increasing the installed terminal power.
  • the present invention enables easy use of antennas of large dimensions, which is difficult with conventional terminals without increasing the generator voltage to provide the sufficient current.
  • Another advantage of the present invention is that it eases the impedance matching of the antenna with respect to control circuit 2 .
  • the impedance Zpeq seen by the generator (circuit 2 ) providing the high-frequency excitation voltage can be generally written as:
  • the ratio between inductances Lb and Lp may, for example, be modified, or a resistor may be introduced in parallel in circuit 21 .
  • imaginary part Xp of impedance Zpeq is a function of inductance Lp, which is minimized.
  • the impedance may, as a first approximation, be considered as being purely resistive. It is thus particularly easy to obtain an off-load impedance matching (for example, at 50 ⁇ ).
  • An advantage then is that the antenna of the read/write terminal can be easily moved aside from its control circuits. A 50- ⁇ matched impedance cable is sufficient.
  • a transponder when a transponder is present in the field, it has an influence upon the impedance seen by the generator (at the denominator of the real part).
  • FIGS. 3A and 3B show the two sides of an antenna according to a preferred embodiment of the present invention.
  • inductive excitation element Lp is formed of several inductances 31 , 32 , 33 , 34 , 35 , 36 , and 37 in a network, that is, electrically in parallel.
  • Inductances 31 , 32 , 33 , 34 , 35 , 36 , and 37 are coplanar.
  • the inductances are, preferably, distributed in a honeycomb.
  • Each inductance 31 , 32 , 33 , 34 , 35 , 36 , and 37 includes, for example, a single hexagonal spiral.
  • the number of spirals of these inductances may be adapted to the value desired for the resulting inductive element Lp.
  • Terminals 38 and 39 of interconnection of the respective terminals of inductances 31 to 37 form the terminals of element Lp.
  • the inductances are for example formed by depositions of conductive tracks on a printed circuit wafer. A first end of each inductance is connected to terminal 38 . This connection is performed by means of vias 41 and of conductive tracks 42 of the two wafer surfaces (FIGS. 3A and 3B). The second end of each inductance is connected to terminal 39 by means of vias 43 and of tracks 44 .
  • Inductance Lb is formed on the second wafer surface.
  • this inductance is formed of a single spiral 40 approximately delimiting a surface equivalent to that of all the network-connected spirals of inductive element Lp. It thus follows the external contour of the honeycomb.
  • the end terminals of spiral 40 define terminals 24 and 25 of inductance Lb intended for being connected to capacitor Cb (not shown).
  • An advantage of using a network inductive element on the side of the LR circuit is that the voltage and current ratio is maximized between the rejector circuit and the excitation circuit. Indeed, the ratio between the inductances of the rejector circuit and of the excitation circuit is increased.
  • FIG. 4 shows another embodiment of a read and/or write terminal 45 according to the present invention.
  • This embodiment more specifically applies to a terminal intended for operating either in relatively remote coupling with a transponder, or in very close coupling therewith. Indeed, in some applications, it is desired to only exchange information between a transponder and the terminal when said transponder is very close to the terminal. This, to avoid that a pirate device intercepts the data exchanges. In such a case, to use a single terminal, the data exchange sequences must conventionally be adapted and software controls must be performed for an operation in very close coupling allowed to a single transponder.
  • FIG. 4 illustrates that the implementation of the present invention greatly eases an operation in extreme closeness of a read and/or write terminal.
  • a switch 46 is provided in rejector circuit 21 ′. This switch is placed in parallel with inductance Lb and is intended for short-circuiting the rejector circuit and, accordingly, eliminating the coupling with excitation circuit LR. Switch 46 is controlled by circuit 2 , via a connection 47 .
  • switch 46 when the terminal is desired to be dedicated to an operation in extreme closeness, switch 46 is closed. In this case, a transponder that wants to exchange data with the terminal must be placed almost on the terminal's antenna to obtain a magnetic coupling with inductive element Lp. The smaller the value of this inductance, the more it will be necessary for the transponder to be close to the terminal. The operation will here be close to an operation as a transformer. When switch 46 is open, the rejector circuit performs its function and the range of the read and/or write terminal is maximum.
  • the switch is placed in series in the rejector circuit. The operation is then inverted and the opening of the switch turns off the rejector circuit. In this alternative, it will be ascertained that the series resistance of the switch is minimum.
  • FIG. 4 shows a current transformer 22 ′ in series with inductive element Lp, and measurement signal 23 ′ of which is sent to circuit 2 .
  • This current transformer provides a measurement of the current in the excitation circuit.
  • Such an arrangement is here necessary at least for the operation in extreme closeness since a detection can no longer be performed by the rejector circuit. It is however possible to maintain the use of a measurement system, on the rejector circuit side, when the terminal operates in remote range.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Electromagnetism (AREA)
  • Artificial Intelligence (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Health & Medical Sciences (AREA)
  • Near-Field Transmission Systems (AREA)

Abstract

The invention concerns an antenna generating an electromagnetic field for an electromagnetic transponder. and a terminal provided with such an antenna, comprising a first inductive element (Lp) designed to be connected to two terminals (3, 4) applying an energizing voltage (Vg), and a parallel resonant circuit (21) coupled with the first inductive element.

Description

  • The present invention relates to systems using electromagnetic transponders, that is, transmitters and/or receivers (generally mobile) capable of being interrogated in a contactless and wireless manner by a unit (generally fixed), called a read and/or write terminal. Generally, transponders extract the power supply required by the electronic circuits included therein from the high-frequency field radiated by an antenna of the read-write terminal. The present invention more specifically relates to a read and/or write terminal for electromagnetic transponders as well as to the antenna that it includes. [0001]
  • FIG. 1 very schematically shows a conventional example of a read/write [0002] terminal 1 associated with a transponder 10.
  • Generally, [0003] terminal 1 is essentially formed of a series oscillating circuit formed of an inductance L1 in series with a capacitor C1 and a resistor R1. This oscillating circuit is controlled by a device 2 including, among others, an amplifier or antenna coupler and a control circuit exploiting the received data provided, in particular, with a modulator/demodulator and a microprocessor for processing the control signals and the data. The oscillating circuit is excited by a voltage Vg provided by device 2 between terminals 3 and 4. Circuit 2 generally communicates with different input/output circuits (keyboard, screen, means of exchange with a server, etc.) and/or processing circuits, not shown. The circuits of the read/write terminal draw the power necessary to their operation from a supply circuit (not shown) connected, for example, to the electric supply system.
  • A [0004] transponder 10, intended for cooperating with a terminal 1, essentially includes a parallel oscillating circuit. This circuit is formed of an inductance L2 in parallel with a capacitor C2 between two input terminals 11, 12 of a control and processing circuit 13. Terminals 11, 12 are in practice connected to the input of a rectifying means (not shown), the outputs of which form D.C. supply terminals of the circuits internal to transponder 10. These circuits generally include, essentially, a microprocessor, a memory, a demodulator of the signals that may be received from terminal 1, and a modulator for transmitting information to the terminal.
  • The oscillating circuits of the terminal and of the transponder are generally tuned on a same frequency corresponding to the frequency of excitation signal Vg of the terminal's oscillating circuit. This high-frequency signal (for example, at 13.56 MHz) is not only used as a carrier of data transmission from the terminal to the transponder, but also as a remote supply carrier for the transponders located in the terminal's field. When a [0005] transponder 10 is located in the field of a terminal 1, a high-frequency voltage is generated across terminals 11 and 12 of the transponder's resonant circuit. This voltage, after being rectified and possibly clipped, provides the supply voltage of electronic circuits 13 of the transponder.
  • The high-frequency carrier transmitted by the terminal is generally modulated in amplitude by said terminal according to different coding techniques to transmit data and/or control signals to one or several transponders in the field. In return, the data transmission from the transponder to a terminal is generally performed by modulating the load formed by resonant circuit L2, C2. The load variation is performed at the rate of a sub-carrier having a frequency (for example, 847.5 kHz) smaller than that of the carrier. This load variation can then be detected by the terminal as an amplitude variation or as a phase variation by means, for example, of a measurement of the voltage across capacitor C1 or of current Ig in the oscillating circuit. In FIG. 1, the measurement signal has been symbolized by a connection [0006] 5 in dotted lines connecting the midpoint of the series connection of inductance L1 and capacitor C1 to circuit 2.
  • A problem which arises in conventional transponder systems is that they generally have a limited range. The system range corresponds to the limiting distance beyond which the field sensed by a transponder is too small to enable extraction of the power necessary for its operation therefrom. The limited range is essentially due to the maximum admissible magnetic field, which is set by standards. Conventionally, to increase the range, the diameter of the antenna is desired to be increased, to avoid exceeding this maximum allowed magnetic field. Now, increasing the diameter amounts to increasing excitation current Ig in proportions that are not desirable, among others, for power consumption reasons. [0007]
  • An object of the present invention is to improve the range of electromagnetic transponder read/write terminals. [0008]
  • The present invention more specifically aims at providing a novel long-range electromagnetic field generation antenna. [0009]
  • The present invention also aims at requiring no modification of the transponders and, accordingly, at being able to operate with any conventional transponder. [0010]
  • The present invention also aims at reducing or minimizing the power consumption of the terminal. [0011]
  • To achieve these objects, the present invention provides an antenna for generating an electromagnetic field for an electromagnetic transponder, including a first inductive element intended for being connected to two terminals of application of an excitation voltage, and a parallel resonant circuit coupled with the first inductive element. [0012]
  • According to an embodiment of the present invention, said resonant circuit includes a second inductive element, the value of which is chosen to be greater than the value of the first inductive element with a ratio depending on a desired field amplification. [0013]
  • According to an embodiment of the present invention, the first inductive element is formed of several inductances associated in a network. [0014]
  • According to an embodiment of the present invention, the inductive element(s) are formed of planar windings. [0015]
  • According to an embodiment of the present invention, the two inductive elements are in parallel planes. [0016]
  • According to an embodiment of the present invention, the distance that separates the respective planes of the inductive elements is chosen according to the power consumption of the transponders for which the antenna is intended and to the desired range. [0017]
  • The present invention also provides a terminal for generating a high-frequency electromagnetic field for at least one transponder entering this field, the terminal including a resonant circuit, magnetically coupled to an excitation circuit including a first inductive element and having no capacitive element. [0018]
  • According to an embodiment of the present invention, the resonant circuit is formed of a second inductive element and of a capacitive element in parallel, and is tuned to the frequency of an excitation signal of the first inductive element. [0019]
  • According to an embodiment of the present invention, said resonant circuit includes a control switch.[0020]
  • The foregoing objects, features and advantages of the present invention, will be discussed in detail in the following non-limiting description of specific embodiments in connection with the accompanying drawings. [0021]
  • FIG. 1, previously described, shows a conventional example of a transponder system of the type to which the present invention applies; [0022]
  • FIG. 2, schematically shows a first embodiment of a read and/or write terminal, provided with an antenna according to the present invention, and associated with a conventional transponder; [0023]
  • FIGS. 3A and 3B show an antenna according to a second embodiment of the present invention; and [0024]
  • FIG. 4 shows an alternative embodiment of a terminal according to the present invention.[0025]
  • The same elements have been referred to with the same references in the different drawings. For clarity, only those elements which are necessary to the understanding of the present invention have been illustrated in the drawings and will be described hereafter. In particular, the internal structures of the electronic circuits of a transponder and of a read and/or write terminal have not been detailed. [0026]
  • A feature of the present invention is to provide the antenna of a read and/or write terminal in the form of an LR circuit coupled to a resonant LC circuit. According to the present invention, the LR circuit is excited by the high-frequency generator of the terminal. The excitation frequency is, conventionally, that of the remote supply carrier and of the possible data to be transmitted. The resonant circuit forms a rejector circuit formed of an inductance and of a capacitor. It is in practice an RLC circuit with as small a resistance as possible corresponding to the series resistances of the inductance and of the capacitor. [0027]
  • Another feature of the present invention is to provide a value of the inductance of the rejector circuit greater than that of the LR excitation circuit. Thus, the voltage developed across the capacitor of the rejector circuit is greater than the excitation voltage of the LR circuit. According to the present invention, the quality factor of the rejector circuit is desired to be maximized to favor the amplification created by its coupling with the LR excitation circuit. The quality factor is inversely proportional to the sum of the series resistances and to the square root of the capacitance of the rejector circuit, and directly proportional to the square root of its inductance. Accordingly, the inductance is desired to be maximized and the series resistances and the capacitance are desired to be minimized. [0028]
  • FIG. 2 very schematically shows a first embodiment of a read and/or write terminal according to the present invention. [0029]
  • Conventionally, a [0030] terminal 20 according to the present invention includes circuits 2 for processing, controlling, and analyzing data to be exchanged with a transponder 10, also conventional. A high-frequency voltage Vg used as a remote power supply carrier and/or as a modulation carrier for a transponder is provided across output terminals 3 and 4 of circuit 2. According to the present invention, terminals 3 and 4 are connected to a series LR circuit formed of a resistor R1 in series with an inductance Lp. Inductance Lp is intended to be coupled with an inductance Lb of a rejector circuit 21 associated with the LR circuit. Circuit 21 also includes a capacitor Cb, the two electrodes of which are respectively connected to the two terminals 24 and 25 of inductance Lb. According to the present invention, the inductive LR circuit, connected across terminals 3 and 4 of circuit 2, includes no capacitor. Thus, there is no tuning of the excitation circuit on the remote supply carrier frequency. According to the present invention, this tuning is transferred to rejector circuit 21. For the latter, the respective values of inductance Lb and of capacitance Cb are selected so that the resonance frequency of this circuit corresponds to the remote supply carrier of the system (for example, 13.56 MHz).
  • According to the present invention, inductances Lp and Lb are, preferably, made in the form of planar inductances having one or several spirals. The inductances are placed in parallel planes to increase or maximize the magnetic coupling between them. This coupling is symbolized in FIG. 2 by mutual inductance M between the LR and LC circuits. [0031] Transponder 10 is a conventional transponder, the present invention requiring no modification of the transponder for its implementation. When transponder 10 is present in the terminal's field, it is in magnetic coupling (mutual inductance M′) with the rejector circuit, from which it draws the power necessary to its operation.
  • The fact of placing a transponder in the antenna's field amounts to increasing the series resistance of [0032] rejector circuit 21, and thus reduces its quality factor and the current flow therethrough. This causes power consumption on the side of excitation circuit R1-Lp. However, the terminal's generator can just provide an energizing current to the rejector circuit where the current and the voltage are naturally high.
  • Inductance Lp is chosen to be as small as possible to optimize the system efficiency and maximize the use of the installed power of the generator providing voltage Vg. The value of inductance Lb of [0033] rejector circuit 21 is chosen to be as high as possible to maximize the system range. Indeed, the higher ratio Lb/Lp, the greater the ratio between the voltage developed across capacitor Cb and voltage Vg.
  • According to a preferred embodiment of the present invention, the interval between the planar inductances, arranged in parallel planes, is adapted to the transponders for which the terminal is intended. According to the charge level represented by different transponders (in particular, according to whether they include or not a microprocessor) and according to the desired range, the coupling between the excitation and rejector circuits can be optimized. In the case of low-power consumption transponders and where a large range is desired, the antenna's inductances will be drawn away from each other to maximize the overvoltage generated across the rejector circuit. For example, an interval ranging between approximately 0.5 cm and a few centimeters will be selected. Conversely, for transponders having a higher power consumption, the coupling between inductances must be maximized so that the load represented by the transponders does not alter too much the quality factor of the rejector circuit. The antenna's inductances are then placed as close as possible to each other. The interval of course depends, among others, on the diameter of the inductances and on the quality coefficient of the rejector circuit. [0034]
  • An advantage of the present invention is that it enables increasing the range of a read and/or write terminal for a given voltage Vg and excitation current Ig. [0035]
  • Another advantage of the present invention is that it requires no modification of existing transponders. [0036]
  • The detection of a back modulation coming from a transponder can be performed either on the LR circuit or in [0037] LC circuit 21. In the embodiment of FIG. 2, a current transformer 22 having the function of measuring the current in rejector circuit 21 has been symbolized. A connection 23 provides the result of this measurement to circuit 2. As an alternative, the measurement may be performed in the LR circuit. However, it is easier to detect variations in the rejector circuit where the signal levels are higher. It will however be ascertained that this measurement disturbs as little as possible the quality factor of the rejector circuit. For example, if a voltage measurement is performed across capacitor Cb, it will be ascertained to use a measurement element with a high input impedance.
  • The present invention enables increasing the transmitted magnetic field without increasing either the current provided by the generator or voltage Vg, and thus without increasing the installed terminal power. For a same terminal with a given installed power, the present invention enables easy use of antennas of large dimensions, which is difficult with conventional terminals without increasing the generator voltage to provide the sufficient current. [0038]
  • Another advantage of the present invention is that it eases the impedance matching of the antenna with respect to control [0039] circuit 2. Indeed, the impedance Zpeq seen by the generator (circuit 2) providing the high-frequency excitation voltage can be generally written as:
  • Zpeq=Rp+j.Xp,
  • where Rp represents the following real part: [0040] Rp = ω 2 · k pb 2 · Lp · Lb Rb , and
    Figure US20030169169A1-20030911-M00001
  • where Xp represents the following imaginary part: [0041]
  • Xp=ω.×Lp,
  • with k[0042] pb representing the magnetic coupling coefficient between the excitation and rejector circuits, and Rb representing the equivalent resistance of circuit 21 (sum of the parasitic resistances of capacitor Cb and of inductance Lb). In real part Rp, no account has been taken of resistance R1, which corresponds in practice to the output resistance of the excitation generator. The series resistance of inductance Lp has further been neglected. The taking into account of these resistive elements merely amounts to adding their respective values to resistance Rb indicated hereabove.
  • To adapt the antenna's impedance, the ratio between inductances Lb and Lp may, for example, be modified, or a resistor may be introduced in parallel in [0043] circuit 21.
  • Further, imaginary part Xp of impedance Zpeq is a function of inductance Lp, which is minimized. Accordingly, the impedance may, as a first approximation, be considered as being purely resistive. It is thus particularly easy to obtain an off-load impedance matching (for example, at 50 Ω). An advantage then is that the antenna of the read/write terminal can be easily moved aside from its control circuits. A 50-Ω matched impedance cable is sufficient. Of course, when a transponder is present in the field, it has an influence upon the impedance seen by the generator (at the denominator of the real part). [0044]
  • FIGS. 3A and 3B show the two sides of an antenna according to a preferred embodiment of the present invention. According to this preferred embodiment, inductive excitation element Lp is formed of [0045] several inductances 31, 32, 33, 34, 35, 36, and 37 in a network, that is, electrically in parallel. Inductances 31, 32, 33, 34, 35, 36, and 37 are coplanar. The inductances are, preferably, distributed in a honeycomb. Each inductance 31, 32, 33, 34, 35, 36, and 37 includes, for example, a single hexagonal spiral. The number of spirals of these inductances may be adapted to the value desired for the resulting inductive element Lp. Terminals 38 and 39 of interconnection of the respective terminals of inductances 31 to 37 form the terminals of element Lp. The inductances are for example formed by depositions of conductive tracks on a printed circuit wafer. A first end of each inductance is connected to terminal 38. This connection is performed by means of vias 41 and of conductive tracks 42 of the two wafer surfaces (FIGS. 3A and 3B). The second end of each inductance is connected to terminal 39 by means of vias 43 and of tracks 44.
  • The network association of the inductances must be such that all inductances in the network generate fields, the lines of which add (all are in the same direction). [0046]
  • Inductance Lb is formed on the second wafer surface. In this preferred embodiment, this inductance is formed of a [0047] single spiral 40 approximately delimiting a surface equivalent to that of all the network-connected spirals of inductive element Lp. It thus follows the external contour of the honeycomb. The end terminals of spiral 40 define terminals 24 and 25 of inductance Lb intended for being connected to capacitor Cb (not shown).
  • An advantage of using a network inductive element on the side of the LR circuit is that the voltage and current ratio is maximized between the rejector circuit and the excitation circuit. Indeed, the ratio between the inductances of the rejector circuit and of the excitation circuit is increased. [0048]
  • Another advantage of using network inductive elements in the excitation circuit is that this further eases the impedance matching. Indeed, the value of inductance Lp, which intervenes in the imaginary part of the impedance of the excitation circuit, is minimized. [0049]
  • FIG. 4 shows another embodiment of a read and/or write terminal [0050] 45 according to the present invention. This embodiment more specifically applies to a terminal intended for operating either in relatively remote coupling with a transponder, or in very close coupling therewith. Indeed, in some applications, it is desired to only exchange information between a transponder and the terminal when said transponder is very close to the terminal. This, to avoid that a pirate device intercepts the data exchanges. In such a case, to use a single terminal, the data exchange sequences must conventionally be adapted and software controls must be performed for an operation in very close coupling allowed to a single transponder.
  • FIG. 4 illustrates that the implementation of the present invention greatly eases an operation in extreme closeness of a read and/or write terminal. For this purpose, a [0051] switch 46 is provided in rejector circuit 21′. This switch is placed in parallel with inductance Lb and is intended for short-circuiting the rejector circuit and, accordingly, eliminating the coupling with excitation circuit LR. Switch 46 is controlled by circuit 2, via a connection 47.
  • For example, when the terminal is desired to be dedicated to an operation in extreme closeness, [0052] switch 46 is closed. In this case, a transponder that wants to exchange data with the terminal must be placed almost on the terminal's antenna to obtain a magnetic coupling with inductive element Lp. The smaller the value of this inductance, the more it will be necessary for the transponder to be close to the terminal. The operation will here be close to an operation as a transformer. When switch 46 is open, the rejector circuit performs its function and the range of the read and/or write terminal is maximum.
  • As an alternative, the switch is placed in series in the rejector circuit. The operation is then inverted and the opening of the switch turns off the rejector circuit. In this alternative, it will be ascertained that the series resistance of the switch is minimum. [0053]
  • The embodiment of FIG. 4 shows a [0054] current transformer 22′ in series with inductive element Lp, and measurement signal 23′ of which is sent to circuit 2. This current transformer provides a measurement of the current in the excitation circuit. Such an arrangement is here necessary at least for the operation in extreme closeness since a detection can no longer be performed by the rejector circuit. It is however possible to maintain the use of a measurement system, on the rejector circuit side, when the terminal operates in remote range.
  • Of course, the present invention is likely to have various alterations, modifications, and improvements which will readily occur to those skilled in the art. In particular, the sizing of the different components of a read and/or write terminal according to the present invention is within the abilities of those skilled in the art based on the functional indications given hereabove. [0055]

Claims (9)

1. An antenna for generating an electromagnetic field for an electromagnetic transponder, including:
a first inductive element (Lp) intended for being connected to two terminals (3, 4) of application of an excitation voltage (Vg); and
a parallel resonant circuit (21, 21′) coupled with the first inductive element.
2. The antenna of claim 1, characterized in that the first inductive element (Lp) is formed of several inductances (31, 32, 33, 34, 35, 36, 37) organized in a network.
3. The antenna of claim 1 or 2, characterized in that the inductive element(s) (Lp), Lb) are formed of planar windings.
4. The antenna of claim 3 characterized in that the two inductive elements (Lp, Lb) are in parallel planes.
5. The antenna of claim 4, characterized in that the distance that separates the respective planes of the inductive elements (Lp, Lb) is chosen according to the power consumption of the transponders for which the antenna is intended and to the desired range.
6. A terminal (20, 45) for generating a high-frequency electromagnetic field for at least one transponder (10) entering this field, characterized in that it includes a resonant circuit (21, 21′), magnetically coupled to an excitation circuit including a first inductive element (Lp) and having no capacitive element, said resonant circuit including a second inductive element (Lb), the value of which is chosen to be greater than the value of the first inductive element with a ratio depending on a desired field amplification.
7. The terminal of claim 1, characterized in that the resonant circuit (21, 21′) is formed of a second inductive element (Lb) and of a capacitive element (Cb) in parallel, and is tuned to the frequency of an excitation signal (Vg) of the first inductive element (Lp).
8. The terminal of claim 6 or 7, characterized in that said inductive elements (Lp, Lb) form the antenna of any of claims 1 to 6.
9. The terminal of any of claims 6 to 8, characterized in that said resonant circuit (21′) includes a control switch (46).
US10/344,880 2000-08-17 2001-08-16 Antenna generating an electromagnetic field for transponder Abandoned US20030169169A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US10/344,880 US20030169169A1 (en) 2000-08-17 2001-08-16 Antenna generating an electromagnetic field for transponder
US12/560,184 US8130159B2 (en) 2000-08-17 2009-09-15 Electromagnetic field generation antenna for a transponder

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR0010699A FR2813149A1 (en) 2000-08-17 2000-08-17 ANTENNA FOR GENERATING AN ELECTROMAGNETIC FIELD FOR TRANSPONDER
US10/344,880 US20030169169A1 (en) 2000-08-17 2001-08-16 Antenna generating an electromagnetic field for transponder
PCT/FR2001/002621 WO2002015116A1 (en) 2000-08-17 2001-08-16 Antenna generating an electromagnetic field for transponder

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US12/560,184 Continuation US8130159B2 (en) 2000-08-17 2009-09-15 Electromagnetic field generation antenna for a transponder

Publications (1)

Publication Number Publication Date
US20030169169A1 true US20030169169A1 (en) 2003-09-11

Family

ID=29585772

Family Applications (2)

Application Number Title Priority Date Filing Date
US10/344,880 Abandoned US20030169169A1 (en) 2000-08-17 2001-08-16 Antenna generating an electromagnetic field for transponder
US12/560,184 Expired - Fee Related US8130159B2 (en) 2000-08-17 2009-09-15 Electromagnetic field generation antenna for a transponder

Family Applications After (1)

Application Number Title Priority Date Filing Date
US12/560,184 Expired - Fee Related US8130159B2 (en) 2000-08-17 2009-09-15 Electromagnetic field generation antenna for a transponder

Country Status (1)

Country Link
US (2) US20030169169A1 (en)

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020164813A1 (en) * 2001-05-04 2002-11-07 Colvin Arthur E. Electro-optical sensing device with reference channel
US20040054385A1 (en) * 2000-06-29 2004-03-18 Lesho Jeffery C. Implanted sensor processing system and method
US20040206916A1 (en) * 2003-04-15 2004-10-21 Sensors For Medicine And Science, Inc. Printed circuit board with integrated antenna and implantable sensor processing system with integrated printed circuit board antenna
US20050179056A1 (en) * 2004-02-18 2005-08-18 Teggatz Ross E. System for resonant circuit tuning
US20070051807A1 (en) * 2003-08-13 2007-03-08 Koichi Yamaguchi Reader/writer and mobile communication apparatus
US20070143048A1 (en) * 2005-12-02 2007-06-21 Semiconductor Energy Laboratory Co., Ltd. Test method of microsctructure body and micromachine
US20090251291A1 (en) * 2008-04-01 2009-10-08 Assa Abloy Ab Switched capacitance method for the detection of, and subsequent communication with a wireless transponder device using a single antenna
US20100259390A1 (en) * 2006-03-31 2010-10-14 Assa Abloy Ab Transponder detector for an rfid system generating a progression of detection signals
US7822450B2 (en) 2005-04-15 2010-10-26 Sensors For Medicine And Science, Inc. Optical-based sensing devices
US20110128050A1 (en) * 2008-07-14 2011-06-02 W.W.I.M. Ltd. Device and method for reducing harmful effects of electromagnetic radiation
US8233953B2 (en) 1998-08-26 2012-07-31 Sensors For Medicine And Science Optical-based sensing devices
US9344156B2 (en) 2011-06-03 2016-05-17 Stmicroelectronics (Rousset) Sas Protection of communication by an electromagnetic transponder
US9356656B2 (en) 2011-06-03 2016-05-31 Stmicroelectronics (Rousset) Sas Assistance for positioning a transponder
US9407307B2 (en) 2011-06-03 2016-08-02 Stmicroelectronics (Rousset) Sas Transponder positioning aid
US9507975B2 (en) 2011-06-03 2016-11-29 Stmicroelectronics (Rousset) Sas Protection of communication between an electromagnetic transponder and a terminal
US9508033B2 (en) 2009-06-19 2016-11-29 Stmicroelectronics (Rousset) Sas Power management in an electromagnetic transponder

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9479225B2 (en) * 2010-05-13 2016-10-25 Qualcomm Incorporated Resonance detection and control within a wireless power system
FR2991799B1 (en) * 2012-06-11 2015-05-29 St Microelectronics Rousset ADAPTING AN ANTENNA CIRCUIT FOR NEAR FIELD COMMUNICATION TERMINAL
KR102144360B1 (en) * 2012-12-05 2020-08-13 삼성전자주식회사 Smart nfc antenna matching network system and user device including the same
CN104777936B (en) * 2015-04-16 2016-08-24 京东方科技集团股份有限公司 Touch-control driver element and circuit, display floater and display device
US10950378B2 (en) 2018-03-22 2021-03-16 The Chinese University Of Hong Kong Methods and systems for controlling electromagnetic field generators

Citations (97)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2411555A (en) * 1941-10-15 1946-11-26 Standard Telephones Cables Ltd Electric wave filter
US3618089A (en) * 1969-01-29 1971-11-02 Moran Instr Corp Range and time measure system
US4068232A (en) * 1976-02-12 1978-01-10 Fairchild Industries, Inc. Passive encoding microwave transponder
US4209783A (en) * 1977-03-30 1980-06-24 Tokyo Shibaura Electric Co., Ltd. Object identification system
US4258348A (en) * 1979-11-13 1981-03-24 Stb Transformer Company Current measuring transformer
US4278977A (en) * 1979-05-04 1981-07-14 Rca Corporation Range determining system
US4375289A (en) * 1977-07-19 1983-03-01 PRECITEC Gesellschaft fur Prazisionstechnik und Elektronik mbH & Co. Entwicklungs und Vertriebs-KG Apparatus for monitoring a boundary line
US4408185A (en) * 1978-11-13 1983-10-04 Elsmark A/S Process for transferring information and system for carrying out the process
US4593412A (en) * 1984-05-21 1986-06-03 Multi-Elmac Company Integrated oscillator antenna for low power, low harmonic radiation
US4656472A (en) * 1985-01-23 1987-04-07 Walton Charles A Proximity identification system with power aided identifier
US4660192A (en) * 1985-04-11 1987-04-21 Pomatto Sr Robert P Simultaneous AM and FM transmitter and receiver
US4673932A (en) * 1983-12-29 1987-06-16 Revlon, Inc. Rapid inventory data acquistion system
US4706050A (en) * 1984-09-22 1987-11-10 Smiths Industries Public Limited Company Microstrip devices
US4782308A (en) * 1986-03-07 1988-11-01 Iskra-Sozd Elektrokovinske Industrije N.Sol.O Circuit arrangement of a reading device for electromagnetic identification cards
US4802808A (en) * 1986-07-30 1989-02-07 Maschinenbau Gabler Gmbh Stacking apparatus for deep-drawn articles of plastics of plastics material
US4814595A (en) * 1987-03-27 1989-03-21 Electo-Galil Ltd. Electronic data communications system
US4827266A (en) * 1985-02-26 1989-05-02 Mitsubishi Denki Kabushiki Kaisha Antenna with lumped reactive matching elements between radiator and groundplate
US4928108A (en) * 1983-12-20 1990-05-22 Bsh Electronics, Ltd. Electrical signal separating device having isolating and matching circuitry for split passband matching
US4963887A (en) * 1988-08-31 1990-10-16 Yamatake-Honeywell Co., Ltd. Full duplex transponder system
US5013898A (en) * 1986-11-03 1991-05-07 Mars Incorporated Data detection, power transfer and power regulation for data storage devices
US5055853A (en) * 1988-10-03 1991-10-08 Garnier Robert C Magnetic frill generator
US5084699A (en) * 1989-05-26 1992-01-28 Trovan Limited Impedance matching coil assembly for an inductively coupled transponder
US5099227A (en) * 1989-07-18 1992-03-24 Indala Corporation Proximity detecting apparatus
US5126749A (en) * 1989-08-25 1992-06-30 Kaltner George W Individually fed multiloop antennas for electronic security systems
US5142292A (en) * 1991-08-05 1992-08-25 Checkpoint Systems, Inc. Coplanar multiple loop antenna for electronic article surveillance systems
US5202644A (en) * 1959-06-11 1993-04-13 Ail Systems, Inc. Receiver apparatus
US5214409A (en) * 1991-12-03 1993-05-25 Avid Corporation Multi-memory electronic identification tag
US5235326A (en) * 1991-08-15 1993-08-10 Avid Corporation Multi-mode identification system
US5305008A (en) * 1991-08-12 1994-04-19 Integrated Silicon Design Pty. Ltd. Transponder system
US5324315A (en) * 1993-08-12 1994-06-28 Medtronic, Inc. Closed-loop downlink telemetry and method for implantable medical device
US5382952A (en) * 1992-01-22 1995-01-17 Indala Corporation Transponder for proximity identification system
US5452344A (en) * 1992-05-29 1995-09-19 Datran Systems Corporation Communication over power lines
US5493267A (en) * 1992-03-06 1996-02-20 Aktiebolaget Electrolux Arrangement for the transfer of control commands in an apparatus or a machine operated from the mains
US5504485A (en) * 1994-07-21 1996-04-02 Amtech Corporation System for preventing reading of undesired RF signals
US5517194A (en) * 1994-02-10 1996-05-14 Racom Systems, Inc. Passive RF transponder and method
US5519381A (en) * 1992-11-18 1996-05-21 British Technology Group Limited Detection of multiple articles
US5521602A (en) * 1994-02-10 1996-05-28 Racom Systems, Inc. Communications system utilizing FSK/PSK modulation techniques
US5525993A (en) * 1995-05-12 1996-06-11 The Regents Of The University Of California Microwave noncontact identification transponder using subharmonic interrogation and method of using the same
US5541604A (en) * 1993-09-03 1996-07-30 Texas Instruments Deutschland Gmbh Transponders, Interrogators, systems and methods for elimination of interrogator synchronization requirement
US5541958A (en) * 1992-12-11 1996-07-30 Mitsubishi Denki Kabushiki Kaisha Clock recovery circuit of demodulator
US5550536A (en) * 1994-08-17 1996-08-27 Texas Instruments Deutschland Gmbh Circuit frequency following technique transponder resonant
US5604411A (en) * 1995-03-31 1997-02-18 Philips Electronics North America Corporation Electronic ballast having a triac dimming filter with preconditioner offset control
US5619529A (en) * 1992-07-20 1997-04-08 Mitsubishi Denki Kabushiki Kaisha Non-contact IC card and non-contact IC card reader/writer
US5621411A (en) * 1993-10-04 1997-04-15 Texas Instruments Incorporated Positioning with RF-ID transponders
US5691605A (en) * 1995-03-31 1997-11-25 Philips Electronics North America Electronic ballast with interface circuitry for multiple dimming inputs
US5767503A (en) * 1994-09-13 1998-06-16 Gemplus Method for the manufacture of contact-free cards
US5801372A (en) * 1994-10-06 1998-09-01 Mitsubishi Denki Kabushiki Kaisha Non-contact IC card with antenna switching circuit
US5883582A (en) * 1997-02-07 1999-03-16 Checkpoint Systems, Inc. Anticollision protocol for reading multiple RFID tags
US5889273A (en) * 1995-09-19 1999-03-30 Kabushiki Kaisha Toshiba Wireless communication data storing medium for receiving a plurality of carriers of proximate frequencies and a transmission/receiving method
US5903150A (en) * 1996-06-03 1999-05-11 Roznitsky; Samuel Antenna system for NMR and MRI apparatus
US5905444A (en) * 1995-11-09 1999-05-18 Siemens Aktiengesellschaft Anti-theft system for a motor vehicle
US5955950A (en) * 1998-07-24 1999-09-21 Checkpoint Systems, Inc. Low noise signal generator for use with an RFID system
US6014088A (en) * 1995-11-28 2000-01-11 Ronald Barend Van Santbrink Method and system for contactless exchange of data between a read/write unit and one or more information carriers
US6025780A (en) * 1997-07-25 2000-02-15 Checkpoint Systems, Inc. RFID tags which are virtually activated and/or deactivated and apparatus and methods of using same in an electronic security system
US6028503A (en) * 1996-11-05 2000-02-22 U.S. Philips Corporation Contactless data transmission and receiving device with a synchronous demodulator
US6034640A (en) * 1997-04-01 2000-03-07 Murata Manufacturing Co., Ltd. Antenna device
US6072491A (en) * 1995-12-29 2000-06-06 Silicon Graphics, Inc. Method and computer program product for accessing a web site
US6072383A (en) * 1998-11-04 2000-06-06 Checkpoint Systems, Inc. RFID tag having parallel resonant circuit for magnetically decoupling tag from its environment
US6070803A (en) * 1993-05-17 2000-06-06 Stobbe; Anatoli Reading device for a transponder
US6070804A (en) * 1997-08-12 2000-06-06 Mitsubishi Denki Kabushiki Kaisha Non-contact IC card with monitor for source power
US6100788A (en) * 1997-12-29 2000-08-08 Storage Technology Corporation Multifunctional electromagnetic transponder device and method for performing same
US6127929A (en) * 1997-12-23 2000-10-03 Em Microelectronic-Marin Sa Transponder for half-duplex communication
US6137411A (en) * 1996-02-12 2000-10-24 Rso Corporation N.V. Article surveillance system
US6150986A (en) * 1995-08-16 2000-11-21 Alfa Laval Agri Ab Antenna system comprising driver circuits for transponder
US6154635A (en) * 1995-06-22 2000-11-28 Fujitsu Ten Limited Antenna driving device for transponder
US6172608B1 (en) * 1996-06-19 2001-01-09 Integrated Silicon Design Pty. Ltd. Enhanced range transponder system
US6208235B1 (en) * 1997-03-24 2001-03-27 Checkpoint Systems, Inc. Apparatus for magnetically decoupling an RFID tag
US6229443B1 (en) * 2000-06-23 2001-05-08 Single Chip Systems Apparatus and method for detuning of RFID tag to regulate voltage
US6243013B1 (en) * 1999-01-08 2001-06-05 Intermec Ip Corp. Cascaded DC voltages of multiple antenna RF tag front-end circuits
US6265962B1 (en) * 1997-09-03 2001-07-24 Micron Technology, Inc. Method for resolving signal collisions between multiple RFID transponders in a field
US6272321B1 (en) * 1996-09-13 2001-08-07 Temic Semiconductor Gmbh Method for tuning an oscillating receiver circuit of a transponder built into a RFID system
US6272320B1 (en) * 1997-02-05 2001-08-07 Em Microelectronic-Marin Sa Base station for a contactless interrogation system comprising a phase locked and voltage controlled oscillator
US6281794B1 (en) * 1998-01-02 2001-08-28 Intermec Ip Corp. Radio frequency transponder with improved read distance
US6304169B1 (en) * 1997-01-02 2001-10-16 C. W. Over Solutions, Inc. Inductor-capacitor resonant circuits and improved methods of using same
US6307468B1 (en) * 1999-07-20 2001-10-23 Avid Identification Systems, Inc. Impedance matching network and multidimensional electromagnetic field coil for a transponder interrogator
US6307517B1 (en) * 2000-06-13 2001-10-23 Applied Wireless Identifications Group, Inc. Metal compensated radio frequency identification reader
US6335665B1 (en) * 1999-09-28 2002-01-01 Lucent Technologies Inc. Adjustable phase and delay shift element
US20020008611A1 (en) * 2000-05-12 2002-01-24 Luc Wuidart Validation of the presence of an electromagnetic transponder in the field of an amplitude demodulation reader
US6356738B1 (en) * 1999-02-18 2002-03-12 Gary W. Schneider Method and apparatus for communicating data with a transponder
US6393045B1 (en) * 1997-09-26 2002-05-21 Wherenet Corp. Spread spectrum baseband modulation of magnetic fields for communications and proximity sensing
US6398710B1 (en) * 1999-01-06 2002-06-04 Ball Semiconductor, Inc. Radiation dosimetry system
US6424820B1 (en) * 1999-04-02 2002-07-23 Interval Research Corporation Inductively coupled wireless system and method
US6441804B1 (en) * 1998-02-23 2002-08-27 Kye Systems Corp. Transmitter and receiver for use in a wireless cursor control system
US6446049B1 (en) * 1996-10-25 2002-09-03 Pole/Zero Corporation Method and apparatus for transmitting a digital information signal and vending system incorporating same
US6465903B1 (en) * 1998-06-22 2002-10-15 Stmicroelectronics S.A. Transmission of an operating order via an A.C. supply line
US6473028B1 (en) * 1999-04-07 2002-10-29 Stmicroelectronics S.A. Detection of the distance between an electromagnetic transponder and a terminal
US6476709B1 (en) * 1998-06-22 2002-11-05 Stmicroelectronics S.A. Transmission of digital data over an A.C. supply line
US6483426B1 (en) * 1997-12-10 2002-11-19 Pagnol Frederic Method of identifying a plurality of transponders, analysis apparatus and a transponder for implementing such a method
US6547149B1 (en) * 1999-04-07 2003-04-15 Stmicroelectronics S.A. Electromagnetic transponder operating in very close coupling
US20030098783A1 (en) * 1999-12-15 2003-05-29 Frederic Pagnol Transponder reading device
US6617962B1 (en) * 2000-01-06 2003-09-09 Samsys Technologies Inc. System for multi-standard RFID tags
US6646543B1 (en) * 1997-03-03 2003-11-11 Regie Autonome Des Transports Parisiens Method for managing collisions in a contactless data exchanging system
US6685096B1 (en) * 1999-09-22 2004-02-03 Em Microelectronic-Marin Sa Transponder intended for several different applications
US6690229B2 (en) * 2001-12-21 2004-02-10 Koninklijke Philips Electronics N.V. Feed back current-source circuit
US6703921B1 (en) * 1999-04-07 2004-03-09 Stmicroelectronics S.A. Operation in very close coupling of an electromagnetic transponder system
US6731198B1 (en) * 1999-01-08 2004-05-04 Antaloli Stobbe Security system, transponder and receiver device
US20040113790A1 (en) * 2002-09-23 2004-06-17 Hamel Michael John Remotely powered and remotely interrogated wireless digital sensor telemetry system

Family Cites Families (46)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1341025A (en) 1970-11-17 1973-12-19 English Electric Co Ltd Data transmission over mains supplies
DK362277A (en) 1977-08-15 1979-02-16 Medibit A S ELECTRONIC INFORMATION SYSTEM
ATE14055T1 (en) 1980-04-28 1985-07-15 Paul Rouet METHOD AND SYSTEM FOR THE TRANSMISSION OF MESSAGES AND CONTROL ON AN AC SUPPLY NETWORK.
EP0309201B1 (en) 1987-09-22 1993-05-26 Hitachi Maxell Ltd. Method and system of communication for a non-contact ic card
US4802080A (en) 1988-03-18 1989-01-31 American Telephone And Telegraph Company, At&T Information Systems Power transfer circuit including a sympathetic resonator
US5701121A (en) 1988-04-11 1997-12-23 Uniscan Ltd. Transducer and interrogator device
EP0369622A3 (en) 1988-11-09 1991-04-17 Security Tag Systems, Inc. Proximity reading of coded tag
EP0628223B1 (en) 1992-02-29 1997-02-05 Scantronic Limited Power supply, in particular for alarm system
JP3288478B2 (en) 1992-04-29 2002-06-04 テキサス インスツルメンツ インコーポレイテツド Identification system for remote sensing of environmental conditions
NL9201270A (en) 1992-07-15 1994-02-01 Nedap Nv ANTI-SHOP THEFT ANTENNA WITH ROTATING FIELD.
US5396251A (en) 1992-12-15 1995-03-07 Texas Instruments Deutschland Gmbh Electronic transponder tuning procedure
US5451958A (en) 1993-05-21 1995-09-19 Texas Instruments Deutschland Gmbh Dual standard RF-ID system
US5850416A (en) 1993-06-30 1998-12-15 Lucent Technologies, Inc. Wireless transmitter-receiver information device
NL9301650A (en) 1993-09-24 1995-04-18 Nedap Nv Independent antenna system for detection systems.
US5440594A (en) 1993-12-09 1995-08-08 Bell Communications Research, Inc. Method and apparatus for joint optimization of transmitted pulse shape and receiver timing in digital systems
US5574470A (en) * 1994-09-30 1996-11-12 Palomar Technologies Corporation Radio frequency identification transponder apparatus and method
US6249212B1 (en) 1994-10-05 2001-06-19 Avid Marketing, Inc. Universal electronic identification tag
JPH08123919A (en) 1994-10-28 1996-05-17 Mitsubishi Electric Corp Noncontact ic card system and communication method thereof
DE4444984C1 (en) 1994-12-16 1995-12-14 Siemens Ag Contactless data transmission system using inductive or capacitive coupling
JPH08191259A (en) 1995-01-11 1996-07-23 Sony Chem Corp Transmitter-receiver for contactless ic card system
GB9503352D0 (en) 1995-02-21 1995-04-12 Sinnett Glyn Remote control system
JPH09218263A (en) 1995-10-11 1997-08-19 Texas Instr Inc <Ti> Transponder system and operating method thereof
US5940006A (en) 1995-12-12 1999-08-17 Lucent Technologies Inc. Enhanced uplink modulated backscatter system
DE19546928A1 (en) 1995-12-15 1997-06-19 Diehl Ident Gmbh Inductive high frequency information signal transmitter
FR2746200B1 (en) 1996-03-12 1998-05-29 NON-CONTACT INFORMATION EXCHANGE DEVICE WITH AN ELECTRONIC LABEL
DE19621076C2 (en) 1996-05-24 2001-06-28 Siemens Ag Device and method for the contactless transmission of energy or data
DE19632282A1 (en) 1996-08-09 1998-02-19 Holzer Walter Prof Dr H C Ing Process and device for controlling the brightness of fluorescent lamps
JPH10135882A (en) 1996-10-24 1998-05-22 Toshiba Corp Contactless information recording medium and its data transmission system
FR2757952B1 (en) 1996-12-27 1999-03-19 Gemplus Card Int RADIO TRANSPONDER PROVIDED WITH AN ANTENNA AND A FREQUENCY TUNING CIRCUIT
GB2321726A (en) 1997-01-30 1998-08-05 Motorola Inc Apparatus and method for regulating power on a contactless portable data carrier
ATE229654T1 (en) 1997-02-05 2002-12-15 Em Microelectronic Marin Sa BASE STATION OF A REMOTE INQUIRY SYSTEM WITH A VOLTAGE-CONTROLLED AND PHASE-CONTROLLED OSCILLATOR
JP3916291B2 (en) 1997-03-28 2007-05-16 ローム株式会社 Information communication equipment
JP3792002B2 (en) 1997-04-17 2006-06-28 ローム株式会社 Data communication apparatus, data communication system, and data communication method
JPH1131913A (en) 1997-05-15 1999-02-02 Murata Mfg Co Ltd Chip antenna and mobile communication device using the antenna
JPH11177027A (en) 1997-09-15 1999-07-02 Microchip Technol Inc Integrated-circuit semiconductor chip and single-sided package containing inductive coil and manufacture thereof
DE69831592T2 (en) * 1997-11-14 2006-06-22 Toppan Printing Co. Ltd. COMPOSITE IC CARD
GB9727042D0 (en) 1997-12-22 1998-02-18 Advanced Technology Communicat Tag and detection system
CN1252908A (en) 1998-02-19 2000-05-10 摩托罗拉公司 Data communication terminal and method of adjusting a power signal generated therefrom
FR2776865B1 (en) 1998-03-31 2000-05-05 Commissariat Energie Atomique INDUCTIVE COUPLING TELETRANSMISSION DEVICE
FR2781587B1 (en) 1998-07-21 2000-09-08 Dassault Electronique ADVANCED READER FOR NON-CONTACT BADGES
US6147605A (en) 1998-09-11 2000-11-14 Motorola, Inc. Method and apparatus for an optimized circuit for an electrostatic radio frequency identification tag
US6650226B1 (en) 1999-04-07 2003-11-18 Stmicroelectronics S.A. Detection, by an electromagnetic transponder reader, of the distance separating it from a transponder
FR2792132B1 (en) 1999-04-07 2001-11-02 St Microelectronics Sa READING TERMINAL OF AN ELECTROMAGNETIC TRANSPONDER OPERATING IN VERY CLOSE COUPLING
DE19951378A1 (en) 1999-10-26 2001-05-03 Philips Corp Intellectual Pty Label with electrodes formed on same surface as integrated circuit
US6650227B1 (en) 1999-12-08 2003-11-18 Hid Corporation Reader for a radio frequency identification system having automatic tuning capability
FR2840742A1 (en) 2002-06-06 2003-12-12 St Microelectronics Sa ELECTROMAGNETIC TRANSPONDER READER

Patent Citations (99)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2411555A (en) * 1941-10-15 1946-11-26 Standard Telephones Cables Ltd Electric wave filter
US5202644A (en) * 1959-06-11 1993-04-13 Ail Systems, Inc. Receiver apparatus
US3618089A (en) * 1969-01-29 1971-11-02 Moran Instr Corp Range and time measure system
US4068232A (en) * 1976-02-12 1978-01-10 Fairchild Industries, Inc. Passive encoding microwave transponder
US4209783A (en) * 1977-03-30 1980-06-24 Tokyo Shibaura Electric Co., Ltd. Object identification system
US4375289A (en) * 1977-07-19 1983-03-01 PRECITEC Gesellschaft fur Prazisionstechnik und Elektronik mbH & Co. Entwicklungs und Vertriebs-KG Apparatus for monitoring a boundary line
US4408185A (en) * 1978-11-13 1983-10-04 Elsmark A/S Process for transferring information and system for carrying out the process
US4278977A (en) * 1979-05-04 1981-07-14 Rca Corporation Range determining system
US4258348A (en) * 1979-11-13 1981-03-24 Stb Transformer Company Current measuring transformer
US4928108A (en) * 1983-12-20 1990-05-22 Bsh Electronics, Ltd. Electrical signal separating device having isolating and matching circuitry for split passband matching
US4673932A (en) * 1983-12-29 1987-06-16 Revlon, Inc. Rapid inventory data acquistion system
US4593412A (en) * 1984-05-21 1986-06-03 Multi-Elmac Company Integrated oscillator antenna for low power, low harmonic radiation
US4706050A (en) * 1984-09-22 1987-11-10 Smiths Industries Public Limited Company Microstrip devices
US4656472A (en) * 1985-01-23 1987-04-07 Walton Charles A Proximity identification system with power aided identifier
US4827266A (en) * 1985-02-26 1989-05-02 Mitsubishi Denki Kabushiki Kaisha Antenna with lumped reactive matching elements between radiator and groundplate
US4660192A (en) * 1985-04-11 1987-04-21 Pomatto Sr Robert P Simultaneous AM and FM transmitter and receiver
US4782308A (en) * 1986-03-07 1988-11-01 Iskra-Sozd Elektrokovinske Industrije N.Sol.O Circuit arrangement of a reading device for electromagnetic identification cards
US4802808A (en) * 1986-07-30 1989-02-07 Maschinenbau Gabler Gmbh Stacking apparatus for deep-drawn articles of plastics of plastics material
US5013898A (en) * 1986-11-03 1991-05-07 Mars Incorporated Data detection, power transfer and power regulation for data storage devices
US4814595A (en) * 1987-03-27 1989-03-21 Electo-Galil Ltd. Electronic data communications system
US4963887A (en) * 1988-08-31 1990-10-16 Yamatake-Honeywell Co., Ltd. Full duplex transponder system
US5055853A (en) * 1988-10-03 1991-10-08 Garnier Robert C Magnetic frill generator
US5084699A (en) * 1989-05-26 1992-01-28 Trovan Limited Impedance matching coil assembly for an inductively coupled transponder
US5099227A (en) * 1989-07-18 1992-03-24 Indala Corporation Proximity detecting apparatus
US5126749A (en) * 1989-08-25 1992-06-30 Kaltner George W Individually fed multiloop antennas for electronic security systems
US5142292A (en) * 1991-08-05 1992-08-25 Checkpoint Systems, Inc. Coplanar multiple loop antenna for electronic article surveillance systems
US5305008A (en) * 1991-08-12 1994-04-19 Integrated Silicon Design Pty. Ltd. Transponder system
US5235326A (en) * 1991-08-15 1993-08-10 Avid Corporation Multi-mode identification system
US5214409A (en) * 1991-12-03 1993-05-25 Avid Corporation Multi-memory electronic identification tag
US5382952A (en) * 1992-01-22 1995-01-17 Indala Corporation Transponder for proximity identification system
US5493267A (en) * 1992-03-06 1996-02-20 Aktiebolaget Electrolux Arrangement for the transfer of control commands in an apparatus or a machine operated from the mains
US5452344A (en) * 1992-05-29 1995-09-19 Datran Systems Corporation Communication over power lines
US5619529A (en) * 1992-07-20 1997-04-08 Mitsubishi Denki Kabushiki Kaisha Non-contact IC card and non-contact IC card reader/writer
US5519381A (en) * 1992-11-18 1996-05-21 British Technology Group Limited Detection of multiple articles
US5541958A (en) * 1992-12-11 1996-07-30 Mitsubishi Denki Kabushiki Kaisha Clock recovery circuit of demodulator
US6070803A (en) * 1993-05-17 2000-06-06 Stobbe; Anatoli Reading device for a transponder
US5324315A (en) * 1993-08-12 1994-06-28 Medtronic, Inc. Closed-loop downlink telemetry and method for implantable medical device
US5541604A (en) * 1993-09-03 1996-07-30 Texas Instruments Deutschland Gmbh Transponders, Interrogators, systems and methods for elimination of interrogator synchronization requirement
US5621411A (en) * 1993-10-04 1997-04-15 Texas Instruments Incorporated Positioning with RF-ID transponders
US5521602A (en) * 1994-02-10 1996-05-28 Racom Systems, Inc. Communications system utilizing FSK/PSK modulation techniques
US5517194A (en) * 1994-02-10 1996-05-14 Racom Systems, Inc. Passive RF transponder and method
US5504485A (en) * 1994-07-21 1996-04-02 Amtech Corporation System for preventing reading of undesired RF signals
US5550536A (en) * 1994-08-17 1996-08-27 Texas Instruments Deutschland Gmbh Circuit frequency following technique transponder resonant
US5767503A (en) * 1994-09-13 1998-06-16 Gemplus Method for the manufacture of contact-free cards
US5874725A (en) * 1994-10-06 1999-02-23 Mitsubishi Denki Kabushiki Kaisha Non-contact IC card with phase variation detector
US5801372A (en) * 1994-10-06 1998-09-01 Mitsubishi Denki Kabushiki Kaisha Non-contact IC card with antenna switching circuit
US5831257A (en) * 1994-10-06 1998-11-03 Mitsubishi Denki Kabushiki Kaisha Non-contact IC card including phase-locked loop circuitry
US5604411A (en) * 1995-03-31 1997-02-18 Philips Electronics North America Corporation Electronic ballast having a triac dimming filter with preconditioner offset control
US5691605A (en) * 1995-03-31 1997-11-25 Philips Electronics North America Electronic ballast with interface circuitry for multiple dimming inputs
US5525993A (en) * 1995-05-12 1996-06-11 The Regents Of The University Of California Microwave noncontact identification transponder using subharmonic interrogation and method of using the same
US6154635A (en) * 1995-06-22 2000-11-28 Fujitsu Ten Limited Antenna driving device for transponder
US6150986A (en) * 1995-08-16 2000-11-21 Alfa Laval Agri Ab Antenna system comprising driver circuits for transponder
US5889273A (en) * 1995-09-19 1999-03-30 Kabushiki Kaisha Toshiba Wireless communication data storing medium for receiving a plurality of carriers of proximate frequencies and a transmission/receiving method
US5905444A (en) * 1995-11-09 1999-05-18 Siemens Aktiengesellschaft Anti-theft system for a motor vehicle
US6014088A (en) * 1995-11-28 2000-01-11 Ronald Barend Van Santbrink Method and system for contactless exchange of data between a read/write unit and one or more information carriers
US6072491A (en) * 1995-12-29 2000-06-06 Silicon Graphics, Inc. Method and computer program product for accessing a web site
US6137411A (en) * 1996-02-12 2000-10-24 Rso Corporation N.V. Article surveillance system
US5903150A (en) * 1996-06-03 1999-05-11 Roznitsky; Samuel Antenna system for NMR and MRI apparatus
US6172608B1 (en) * 1996-06-19 2001-01-09 Integrated Silicon Design Pty. Ltd. Enhanced range transponder system
US6272321B1 (en) * 1996-09-13 2001-08-07 Temic Semiconductor Gmbh Method for tuning an oscillating receiver circuit of a transponder built into a RFID system
US6446049B1 (en) * 1996-10-25 2002-09-03 Pole/Zero Corporation Method and apparatus for transmitting a digital information signal and vending system incorporating same
US6028503A (en) * 1996-11-05 2000-02-22 U.S. Philips Corporation Contactless data transmission and receiving device with a synchronous demodulator
US6304169B1 (en) * 1997-01-02 2001-10-16 C. W. Over Solutions, Inc. Inductor-capacitor resonant circuits and improved methods of using same
US6272320B1 (en) * 1997-02-05 2001-08-07 Em Microelectronic-Marin Sa Base station for a contactless interrogation system comprising a phase locked and voltage controlled oscillator
US5883582A (en) * 1997-02-07 1999-03-16 Checkpoint Systems, Inc. Anticollision protocol for reading multiple RFID tags
US6646543B1 (en) * 1997-03-03 2003-11-11 Regie Autonome Des Transports Parisiens Method for managing collisions in a contactless data exchanging system
US6208235B1 (en) * 1997-03-24 2001-03-27 Checkpoint Systems, Inc. Apparatus for magnetically decoupling an RFID tag
US6034640A (en) * 1997-04-01 2000-03-07 Murata Manufacturing Co., Ltd. Antenna device
US6025780A (en) * 1997-07-25 2000-02-15 Checkpoint Systems, Inc. RFID tags which are virtually activated and/or deactivated and apparatus and methods of using same in an electronic security system
US6070804A (en) * 1997-08-12 2000-06-06 Mitsubishi Denki Kabushiki Kaisha Non-contact IC card with monitor for source power
US6265962B1 (en) * 1997-09-03 2001-07-24 Micron Technology, Inc. Method for resolving signal collisions between multiple RFID transponders in a field
US6393045B1 (en) * 1997-09-26 2002-05-21 Wherenet Corp. Spread spectrum baseband modulation of magnetic fields for communications and proximity sensing
US6483426B1 (en) * 1997-12-10 2002-11-19 Pagnol Frederic Method of identifying a plurality of transponders, analysis apparatus and a transponder for implementing such a method
US6127929A (en) * 1997-12-23 2000-10-03 Em Microelectronic-Marin Sa Transponder for half-duplex communication
US6100788A (en) * 1997-12-29 2000-08-08 Storage Technology Corporation Multifunctional electromagnetic transponder device and method for performing same
US6281794B1 (en) * 1998-01-02 2001-08-28 Intermec Ip Corp. Radio frequency transponder with improved read distance
US6441804B1 (en) * 1998-02-23 2002-08-27 Kye Systems Corp. Transmitter and receiver for use in a wireless cursor control system
US6465903B1 (en) * 1998-06-22 2002-10-15 Stmicroelectronics S.A. Transmission of an operating order via an A.C. supply line
US6476709B1 (en) * 1998-06-22 2002-11-05 Stmicroelectronics S.A. Transmission of digital data over an A.C. supply line
US5955950A (en) * 1998-07-24 1999-09-21 Checkpoint Systems, Inc. Low noise signal generator for use with an RFID system
US6072383A (en) * 1998-11-04 2000-06-06 Checkpoint Systems, Inc. RFID tag having parallel resonant circuit for magnetically decoupling tag from its environment
US6398710B1 (en) * 1999-01-06 2002-06-04 Ball Semiconductor, Inc. Radiation dosimetry system
US6731198B1 (en) * 1999-01-08 2004-05-04 Antaloli Stobbe Security system, transponder and receiver device
US6243013B1 (en) * 1999-01-08 2001-06-05 Intermec Ip Corp. Cascaded DC voltages of multiple antenna RF tag front-end circuits
US6356738B1 (en) * 1999-02-18 2002-03-12 Gary W. Schneider Method and apparatus for communicating data with a transponder
US6424820B1 (en) * 1999-04-02 2002-07-23 Interval Research Corporation Inductively coupled wireless system and method
US6473028B1 (en) * 1999-04-07 2002-10-29 Stmicroelectronics S.A. Detection of the distance between an electromagnetic transponder and a terminal
US6703921B1 (en) * 1999-04-07 2004-03-09 Stmicroelectronics S.A. Operation in very close coupling of an electromagnetic transponder system
US6547149B1 (en) * 1999-04-07 2003-04-15 Stmicroelectronics S.A. Electromagnetic transponder operating in very close coupling
US6307468B1 (en) * 1999-07-20 2001-10-23 Avid Identification Systems, Inc. Impedance matching network and multidimensional electromagnetic field coil for a transponder interrogator
US6685096B1 (en) * 1999-09-22 2004-02-03 Em Microelectronic-Marin Sa Transponder intended for several different applications
US6335665B1 (en) * 1999-09-28 2002-01-01 Lucent Technologies Inc. Adjustable phase and delay shift element
US20030098783A1 (en) * 1999-12-15 2003-05-29 Frederic Pagnol Transponder reading device
US6617962B1 (en) * 2000-01-06 2003-09-09 Samsys Technologies Inc. System for multi-standard RFID tags
US20020008611A1 (en) * 2000-05-12 2002-01-24 Luc Wuidart Validation of the presence of an electromagnetic transponder in the field of an amplitude demodulation reader
US6307517B1 (en) * 2000-06-13 2001-10-23 Applied Wireless Identifications Group, Inc. Metal compensated radio frequency identification reader
US6229443B1 (en) * 2000-06-23 2001-05-08 Single Chip Systems Apparatus and method for detuning of RFID tag to regulate voltage
US6690229B2 (en) * 2001-12-21 2004-02-10 Koninklijke Philips Electronics N.V. Feed back current-source circuit
US20040113790A1 (en) * 2002-09-23 2004-06-17 Hamel Michael John Remotely powered and remotely interrogated wireless digital sensor telemetry system

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8233953B2 (en) 1998-08-26 2012-07-31 Sensors For Medicine And Science Optical-based sensing devices
US20040054385A1 (en) * 2000-06-29 2004-03-18 Lesho Jeffery C. Implanted sensor processing system and method
US7553280B2 (en) 2000-06-29 2009-06-30 Sensors For Medicine And Science, Inc. Implanted sensor processing system and method
US20020164813A1 (en) * 2001-05-04 2002-11-07 Colvin Arthur E. Electro-optical sensing device with reference channel
US7800078B2 (en) 2003-04-15 2010-09-21 Sensors For Medicine And Science, Inc. Printed circuit board with integrated antenna and implantable sensor processing system with integrated printed circuit board antenna
US20040206916A1 (en) * 2003-04-15 2004-10-21 Sensors For Medicine And Science, Inc. Printed circuit board with integrated antenna and implantable sensor processing system with integrated printed circuit board antenna
US20070051807A1 (en) * 2003-08-13 2007-03-08 Koichi Yamaguchi Reader/writer and mobile communication apparatus
US7699231B2 (en) 2003-08-13 2010-04-20 Murata Manufacturing Co., Ltd. Reader/writer and mobile communication apparatus
US20050179056A1 (en) * 2004-02-18 2005-08-18 Teggatz Ross E. System for resonant circuit tuning
US7822450B2 (en) 2005-04-15 2010-10-26 Sensors For Medicine And Science, Inc. Optical-based sensing devices
US20070143048A1 (en) * 2005-12-02 2007-06-21 Semiconductor Energy Laboratory Co., Ltd. Test method of microsctructure body and micromachine
US7808253B2 (en) * 2005-12-02 2010-10-05 Semiconductor Energy Laboratory Co., Ltd. Test method of microstructure body and micromachine
US20110006784A1 (en) * 2005-12-02 2011-01-13 Semiconductor Energy Laboratory Co., Ltd. Test method of microstructure body and micromachine
US8558555B2 (en) 2005-12-02 2013-10-15 Semiconductor Energy Laboratory Co., Ltd. Test method of microstructure body and micromachine
US8319612B2 (en) 2006-03-31 2012-11-27 Assa Abloy Ab Transponder detector for an RFID system generating a progression of detection signals
US20100259390A1 (en) * 2006-03-31 2010-10-14 Assa Abloy Ab Transponder detector for an rfid system generating a progression of detection signals
US20090251291A1 (en) * 2008-04-01 2009-10-08 Assa Abloy Ab Switched capacitance method for the detection of, and subsequent communication with a wireless transponder device using a single antenna
US8203429B2 (en) * 2008-04-01 2012-06-19 Assa Abloy Ab Switched capacitance method for the detection of, and subsequent communication with a wireless transponder device using a single antenna
US20110128050A1 (en) * 2008-07-14 2011-06-02 W.W.I.M. Ltd. Device and method for reducing harmful effects of electromagnetic radiation
US8937516B2 (en) * 2008-07-14 2015-01-20 W.W.I.M. Ltd. Device and method for reducing harmful effects of electromagnetic radiation
US9508033B2 (en) 2009-06-19 2016-11-29 Stmicroelectronics (Rousset) Sas Power management in an electromagnetic transponder
US9344156B2 (en) 2011-06-03 2016-05-17 Stmicroelectronics (Rousset) Sas Protection of communication by an electromagnetic transponder
US9356656B2 (en) 2011-06-03 2016-05-31 Stmicroelectronics (Rousset) Sas Assistance for positioning a transponder
US9407307B2 (en) 2011-06-03 2016-08-02 Stmicroelectronics (Rousset) Sas Transponder positioning aid
US9507975B2 (en) 2011-06-03 2016-11-29 Stmicroelectronics (Rousset) Sas Protection of communication between an electromagnetic transponder and a terminal

Also Published As

Publication number Publication date
US8130159B2 (en) 2012-03-06
US20100039337A1 (en) 2010-02-18

Similar Documents

Publication Publication Date Title
US8130159B2 (en) Electromagnetic field generation antenna for a transponder
US6533178B1 (en) Device for contactless transmission of data
US7145451B2 (en) Impedance matching network and multidimensional electromagnetic field coil for a transponder interrogator
AU630730B2 (en) Proximity detecting apparatus
US7173519B2 (en) Circuit arrangement with simplified input circuit for phase modulation in a backscattering transponder
US6173897B1 (en) Universal card interface module for contact free cards
JP4948736B2 (en) Non-contact portable object having one or more non-contact portable peripheral devices
US6173899B1 (en) Method and system for contactless energy transmission and data exchange between a terminal and IC card
JP3475996B2 (en) Non-contact IC card system, IC card reader and IC card
JP3649374B2 (en) Antenna device and card-like storage medium
US20020003498A1 (en) Electromagnetic field generation antenna for a transponder
US20060172702A1 (en) Sizing of an electromagnetic transponder system for an operation in extreme proximity
CN101587558B (en) Recharge of an active transponder
US20090247079A1 (en) Terminal of radio-frequency transmission/reception by inductive coupling
US7046146B2 (en) Electromagnetic field generation device for a transponder
US7049935B1 (en) Sizing of an electromagnetic transponder system for a dedicated distant coupling operation
JP4691825B2 (en) Evaluation of the number of electromagnetic transponders in the reader field
KR20020064451A (en) An amplifying method for RF signals in a contactless IC card system by through a mutual induced amplifying junction antenna and an apparatus therefor
JP4736306B2 (en) An antenna that generates an electromagnetic field for the transponder
GB2326529A (en) Tag interrogation field system
JP3519520B2 (en) Wireless communication system
JPH1166260A (en) Non-contact ic card wound with antenna coil in plural planes
JPH05291991A (en) Non-contact transmitting device
JP2004511939A (en) Notched transmit and / or receive antenna
JP3834666B2 (en) Antenna circuit for reader / writer

Legal Events

Date Code Title Description
AS Assignment

Owner name: STMICROELECTRONICS S.A., FRANCE

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:WUIDART, LUC;BARDOUILLET, MICHEL;REEL/FRAME:014191/0280

Effective date: 20030120

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION