EP0408573A1 - Dispositif d'identification d'objets. - Google Patents

Dispositif d'identification d'objets.

Info

Publication number
EP0408573A1
EP0408573A1 EP89902555A EP89902555A EP0408573A1 EP 0408573 A1 EP0408573 A1 EP 0408573A1 EP 89902555 A EP89902555 A EP 89902555A EP 89902555 A EP89902555 A EP 89902555A EP 0408573 A1 EP0408573 A1 EP 0408573A1
Authority
EP
European Patent Office
Prior art keywords
frequency
resonators
modulation
combination
signal
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.)
Granted
Application number
EP89902555A
Other languages
German (de)
English (en)
Other versions
EP0408573B1 (fr
Inventor
Kurt Olof Edvardsson
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.)
REKONDO TEKNIK AB
Original Assignee
SWEIDCO AB
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
Application filed by SWEIDCO AB filed Critical SWEIDCO AB
Publication of EP0408573A1 publication Critical patent/EP0408573A1/fr
Application granted granted Critical
Publication of EP0408573B1 publication Critical patent/EP0408573B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING SYSTEMS, e.g. PERSONAL CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00—Burglar, theft or intruder alarms
    • G08B13/22—Electrical actuation
    • G08B13/24—Electrical actuation by interference with electromagnetic field distribution
    • G08B13/2402—Electronic Article Surveillance [EAS], i.e. systems using tags for detecting removal of a tagged item from a secure area, e.g. tags for detecting shoplifting
    • G08B13/2405—Electronic Article Surveillance [EAS], i.e. systems using tags for detecting removal of a tagged item from a secure area, e.g. tags for detecting shoplifting characterised by the tag technology used
    • G08B13/2414—Electronic Article Surveillance [EAS], i.e. systems using tags for detecting removal of a tagged item from a secure area, e.g. tags for detecting shoplifting characterised by the tag technology used using inductive tags

Definitions

  • the label can be made highly durable with regard to environmental influences, that they can be made cheaply, and that they obtain a smooth, mechanical con- figuration or construction.
  • the label can be given a sheet form and handled in a manner of a paper sheet (e.g. in a type writer) and may be used as a one- -time use article.
  • the labels may be used in extreme environments (e.g. in stoving furnaces) and conceivably may also be hidden in packages or the like.
  • a principal problem with passive resonators is that the information content is limited in a completely different manner to. e.g., an antenna-connected programmable memory.
  • Another principal limitation of such broadband systems as this is that the range is restricted because government regulations on limited emission of radio waves means that the radiated power must be kept low.
  • the label includes a plurality of resonators and is in ⁇ fluenced by a magnetic field whose frequency is scanned continuously while simultaneously modulating frequency
  • This modulation spreads the power over substantially the same frequency band as that corre ⁇ sponding to the bandwidth of a resonator. During those time intervals when the carrier wave frequency is close to the resonance frequency of one of the resonators, a
  • the scan causes each resonator to engender a pulse and the label as a whole will generate a train of pulses during the scan period.
  • Scan and modulation are controlled in a manner to "normalize" the pulse train and mutually different labels can be separated, one from the other, by different patterns taken by the pulse train.
  • the method of applying a continuous scan renders the system tolerant to uniform displacement of the resonance fre ⁇ quencies of the resonators, e.g. displacements or shifts caused by variations in the properties of the material concerned. Because the system is a broadband system (> 1 octave), the configuration of the transmitter coil is important in achieving a sufficient range, despite the restrictions placed on current strength in the transmitter coil by government permitted radiation or emission levels.
  • Various arrangements of contracting loops are employed for the purpose of providing strong magnetic field in relation to the radiation field.
  • the transmitter coil will create a magnetic field in its close proximity, but because of its two counter-directed halves, according to the Figure 1 embodiment, the radiated power will be relatively weak.
  • the label is excited by the magnetic field and the scan ⁇ ning speed is so low as to enable a resonator to begin to oscillate while the transmitter frequency is still close to the resonator frequency.
  • the frequency of the resonator is f and its Q-value is Q. this can be ex ⁇ pressed such as to take at least Q/4 periods to change the carrier frequency f /Q.
  • the modulation frequency can be selected so that a number of frequency periods are able to pass during the same periode.
  • a re ⁇ DC coil catches a response from an eventual resonator in the immediate proximity, and the response is mixed with a small part of the transmitted signal. Naturally, it is also possible to mix the response with a modified com ⁇ position of the transmitted signal.
  • Figure 2 is a block schematic which illustrates a more practical apparatus, in which, inter alia, the scan is effected proportionally (a given number of % per unit of time) so that all of the resonators will give responses of mutually equal time lengths, even when the scan incorpo ⁇ rates a plurality of octaves.
  • the illustrated apparatus includes a feedback which will ensure that the scan is accurately defined, in order to facilitate evaluation. Both modulation width and amplification are controlled during the scan, thereby enabling the pulse train to be normalized subsequent to running a test label, which is measured now and again.
  • the modulation frequency is, on the other hand, constant in Figure 2, in order to faci ⁇ litate filtration of the signals.
  • Figure 3 illustrates a further modulating method in which a combination of frequency and amplitude modulation is employed to restrict the power transmitted to three frequencies at a time (carrier frequency plus/minus modulation frequency) in order to minimize the bandwidth used and also to reduce disturbance from adjacent resona ⁇ tors during a reading period.
  • the modulation frequency varies in proportion to the carrier frequency, so as to optimize the signal in relation to the bandwidth of the resonators.
  • Figure 4 illustrates this function with the aid of a display diagram in which second harmonics are emphasized for narrow band resonators.
  • phase modulation used here and in the aforegoing is meant also to include phase modulation, which in respect of signals are the same. Both the practical construction and the choice of parameters can vary, however.
  • the range is dependent on a number of parameters, of which some are independent of the signal processing process. However, in the described method there is used a narrow bandwidth (for instance compared with pulsated systems) resulting in the suppression of both external and internal disturbances. It is also important to the function that the resonators alone have a high Q-value (or have a narrow bandwidth on the high frequency side), so that both the transmitter coil and the receiver coil must be given a broad bandwidth and be free from parasite resonances to the greatest possible extent, both within the transmitter frequency band and the possibly occurring harmonics of the transmitter frequency.
  • FIGS 5-6 illustrate two conceivable coil arrangements with built-in transmitter and receiver coil.
  • the trans ⁇ mitter coil has two or more counter-directed parts, so as to enable relatively large current to be used while keep ⁇ ing radiation down.
  • the magnetic field close to the coil will then cause acceptable excitation of the label.
  • the size of the transmitter coil is not critical, but the receiver coil should be approximately the same dimension as the desired range.
  • the orientation or positioning of the label is also of significance, in addition to the range.
  • the labels will "travel" in mutually the same manner, but it may sometimes be necess ⁇ ary to eliminate this dependency, however. Greater in ⁇ dependency can be obtained by employing two perpendicular fields with a 90° phase offset, without needing to measure consecutively in said two directions. Since the geometry of the coils is dependent on use, this geometry will vary with different applications. One requirement of important practical significance is that the coils have a wide band ⁇ width, so as to avoid generating disturbances. In accord ⁇ ance with the invention, the label resonators will have the highest Q-value with good margins.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Computer Security & Cryptography (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Radar Systems Or Details Thereof (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)
  • Near-Field Transmission Systems (AREA)

Abstract

Cette invention concerne un procédé et un appreillage permettant l'identification sans contact d'une étiquette comportant des résonateurs passifs, à l'aide de champs magnétiques à hautes fréquences. Une caractéristique importante du procédé de l'invention est que l'on peut accommoder de grandes quantités d'informations d'intérêt pratique, en dépit du fait que l'on peut donner aux résonateurs une valeur Q qui soit si faible qu'elle permette de donner aux résonateurs la forme, par exemple, de circuits imprimés montés sur une feuille en plastique. L'exigence de stabilité de fréquence des résonateurs est également faible, ce qui permet de produire les étiquettes à faible coût à l'aide de techniques de fabrication appropriées à cet effet, et de les produire pour une utilisation unique. Le procédé est basé sur un signal à haute fréquence balayé sur une large bande de fréquences et modulé en même temps, avec une détection appropriée, la modulation ayant pour résultat une réponse à largeurs de bandes plus étroites par rapport à celle obtenue à l'aide des procédés antérieurs connus, permettant ainsi d'accomoder plus de résonateurs et de les séparer dans une gamme de fréquences donnée. L'appareillage de l'invention mettant en oeuvre le procédé comprend entre autres, un dispositif permettant de commander le balayage, la modulation ainsi que l'amplification sur la bande de fréquences. Une caractéristique importante de l'appareillage de l'invention réside en ce que l'on a prévu un agencement de bobine permettant une gamme comparativement large satisfaisant en même temps les réglementations officielles relatives aux puissances maximum de rayonnement.
EP89902555A 1988-02-10 1989-02-09 Dispositif d'identification d'objets Expired - Lifetime EP0408573B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE8800426A SE501335C2 (sv) 1988-02-10 1988-02-10 Anordning för identifiering av föremål
SE8800426 1988-08-19
PCT/SE1989/000051 WO1989007772A1 (fr) 1988-02-10 1989-02-09 Dispositif d'identification d'objets

Publications (2)

Publication Number Publication Date
EP0408573A1 true EP0408573A1 (fr) 1991-01-23
EP0408573B1 EP0408573B1 (fr) 1996-06-05

Family

ID=20371320

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89902555A Expired - Lifetime EP0408573B1 (fr) 1988-02-10 1989-02-09 Dispositif d'identification d'objets

Country Status (4)

Country Link
EP (1) EP0408573B1 (fr)
DE (1) DE68926619T2 (fr)
SE (1) SE501335C2 (fr)
WO (1) WO1989007772A1 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5083113A (en) * 1990-01-31 1992-01-21 Texas Instruments Incorporated Inductive coupled object identification system and method
FI100491B (fi) * 1995-08-23 1997-12-15 Tuotesuoja Sirpa Jaervensivu K Tuotesuoja-anturin deaktivointilaitteisto
NL1016416C2 (nl) * 2000-10-16 2002-04-18 Nedap Nv Meetapparaat voor het testen van RFID labels.
WO2003062861A1 (fr) * 2002-01-16 2003-07-31 Tagsys Australia Pty Ltd Systeme et procede pour la communication par etiquettes electroniques
CN113474674B (zh) * 2019-03-05 2025-05-30 宝洁公司 对人-产品交互的无线测量

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3798642A (en) * 1972-09-27 1974-03-19 Microlab Fxr Recognition system
US4069472A (en) * 1975-12-25 1978-01-17 Tokyo Shibaura Electric Co., Ltd. Foreground subject-identifying apparatus
US4356477A (en) * 1980-09-30 1982-10-26 Jan Vandebult FM/AM Electronic security system
GB2180123B (en) * 1984-12-21 1989-01-18 Senezco Limited Transponder systems

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8907772A1 *

Also Published As

Publication number Publication date
EP0408573B1 (fr) 1996-06-05
WO1989007772A1 (fr) 1989-08-24
SE8800426D0 (sv) 1988-02-10
SE8800426L (sv) 1989-08-11
DE68926619T2 (de) 1996-10-02
DE68926619D1 (de) 1996-07-11
SE501335C2 (sv) 1995-01-16

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