EP1770666A2 - Resonanzetikett mit ausgeteilter Kapazität - Google Patents

Resonanzetikett mit ausgeteilter Kapazität Download PDF

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Publication number
EP1770666A2
EP1770666A2 EP06076808A EP06076808A EP1770666A2 EP 1770666 A2 EP1770666 A2 EP 1770666A2 EP 06076808 A EP06076808 A EP 06076808A EP 06076808 A EP06076808 A EP 06076808A EP 1770666 A2 EP1770666 A2 EP 1770666A2
Authority
EP
European Patent Office
Prior art keywords
track
turn
tag according
tag
situated
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
EP06076808A
Other languages
English (en)
French (fr)
Other versions
EP1770666B1 (de
EP1770666A3 (de
Inventor
Harm Jacob Kip
Marius Lambertus Tervoert
Paulus Johannes Wilhelmus Maria Van Breemen
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.)
Nederlandsche Apparatenfabriek NEDAP NV
Original Assignee
Nederlandsche Apparatenfabriek NEDAP NV
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 Nederlandsche Apparatenfabriek NEDAP NV filed Critical Nederlandsche Apparatenfabriek NEDAP NV
Publication of EP1770666A2 publication Critical patent/EP1770666A2/de
Publication of EP1770666A3 publication Critical patent/EP1770666A3/de
Application granted granted Critical
Publication of EP1770666B1 publication Critical patent/EP1770666B1/de
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR 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
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR 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
    • G08B13/242—Tag deactivation

Definitions

  • This invention relates to an improved design of a resonant tag for an electronic antishoplifting system. More particularly, the invention relates to a resonant detection tag, in particular a shoplifting detection tag, which is provided with a dielectric which is situated substantially in a plane; a first spiraling electroconductive track on a first side of the dielectric, which first track comprises a plurality of turns; and a second spiraling electroconductive track on a second side of the dielectric, which second track comprises a plurality of turns, and which second side is situated opposite the first side; wherein the first track and the second track spiral in opposite directions, each form an induction and are aligned relative to each other such that at least a part of the first track coincides with at least a part of the second track, so that a distributed capacitance is formed as a result of the mutually aligned tracks.
  • the resonant capacitance is concentrated.
  • a different design of the resonant tags makes use of the distributed capacitance that is present between the upper and lower conductor.
  • Such a tag is described by Vandebult (Polyonics) in US 4,583,099 .
  • Monarch Marking Systems has described a different design of a distributed capacitance resonant tag.
  • the capacitance is provided in a manner distributed between the windings.
  • An example of a widely used tag is described in EP 1 107 205 to Checkpoint.
  • EP 0 665 705 Miyake describes a distributed capacitance tag and a production process to make these tags.
  • a small detection tag contains less material, and hence has less environmental impact, and in particular is cheaper to produce.
  • a major disadvantage of small tags is that the detection distance is limited. This limits the width of the passage in which a tag can be detected, and also the chance of detection diminishes. Hence, there is a great need for a small detection tag having improved sensitivity.
  • the object of the invention is to make an improved design of a distributed capacitance resonant tag by making more efficient use of the portion of the tag surface that is available for the conductors.
  • the sensitivity of a resonant tag is determined by a number of characteristics. Firstly the voltage that is induced in the windings by the interrogation field, secondly the current that proceeds to flow in the windings, in which connection the resonant rise of the current by a factor Q is important, and thirdly the dipole moment that is generated in the tag by this current.
  • a tag according to the invention optimizes the product of these partly conflicting effects.
  • the tag according to the invention may be characterized in that the magnitude of a surface of a cross section of at any rate at least a first part of the first track is greater than the magnitude of a surface of a cross section of at any rate at least a second part of the first track, wherein, in use, the current through the first part of the first track is greater than the current through the second part of the first track.
  • the whole system can be represented by an electric equivalent circuit.
  • a simplified electronic circuit model of such a tag is shown in Fig. 2, where L1 and L11 represent the magnetically coupled coil segments situated above each other. Ditto for L2 and L12, and so forth.
  • the distributed capacitance that occurs between the segments L1 and L11 is represented by the concentrated C1, and similarly for the further segments. This numbering corresponds to the references in Figs. 4 and 5.
  • the number of sections is limited. A better approximation of the distributed effects requires many more sections, but for an analysis of the operation of a distributed capacitance resonant tag this model has good utility. All coils are weakly coupled with a coil, not shown, which represents the interrogation antenna.
  • the preferred embodiment of the invention therefore has the interconnection on the outer side.
  • a single turn along the outer contour is optimal. This holds for tags with a dimension of for instance 4 cm x 4 cm or 5 cm x 5 cm. With smaller tags (3 cm x 3 cm), built up with manageable thicknesses of the foil for the dielectric and with the minimum track widths that are needed for achieving sufficient capacitor surface and an ohmic resistance that is low enough for a sufficiently high Q factor, it is not possible to achieve a resonant frequency of 8 MHz with a single turn. The self-inductance of a single turn is too low for that. For that reason, several turns are needed: in practice between 3 and 7 turns.
  • FIG. 6 The most important components of a preferred embodiment of a tag according to the invention are shown in Figure 6.
  • a suitable dielectric layer is provided between these spirals.
  • the preferred position for contact for connecting the two spirals is indicated on the outer side of the tag by A.
  • the maximum voltage in a tag in a deactivation field will then occur at the open end of the spirals, this is indicated in Figure 6 by the letter B. Accordingly, this is the place of choice for providing a weakening in the dielectric for the purpose of deactivation, or for connecting an RFID chip.
  • the track width has been adjusted stepwise per turn to the prevailing current. This prevents the geometric problems of a continuously proceeding adjustment of the track width.
  • the invention is not limited to the track width shown in the preferred embodiment varying stepwise per turn. Connecting an RFID chip between the spiral coils described is understood to be part of the invention.
  • Fig. 6 parts corresponding to Fig. 1 are provided with the same reference numeral. It is noted that the dielectric 2 is shown schematically transparent. The plane in which the dielectric 2 extends is a flat plane in this example.
  • the resonant tag 1 of Fig. 6 is provided, in addition to the dielectric 2, with a first spiraling electroconductive track 4 which is situated on a first side 6 of the dielectric.
  • a second spiraling electroconductive track 8 is situated on a second side of the dielectric, which second side is situated opposite the first side 6.
  • the first track and the second track have been wound in opposite directions. It holds, therefore, that the first track and the second track spiral in opposite directions.
  • Each track forms an induction.
  • the first track is provided with an outermost turn 14 and an innermost turn 16 as well as intermediate turns 18 and 20.
  • the second track 8 is provided with an outermost turn 14 and an innermost turn 16 as well as intermediate turns 18 and 20.
  • the outermost turn 14 of the first track in this example is situated opposite the outermost turn 14 of the second track, and thus forms a capacitance. The same holds for the innermost turns 16 of the first and second track, the intermediate turns 18 of the first and second track and the intermediate turns 20 of the first and second track.
  • the first track 4 is electroconductively connected with the second track 8 at a position A which is situated at the outermost turns 14 of the first and second track. Furthermore, it holds that, viewed in a direction 22 along the first track from an outermost turn to an innermost turn, the magnitude of the surface of a cross section of the first track decreases. Because in this example the thickness of the first track, viewed in a direction perpendicular to the plane of the dielectric, is constant, it holds that, viewed in the direction 22 along the first track from an outermost turn to an innermost turn, the magnitude of the width of the first track decreases.
  • a width of a first turn (14, 18, 20) that is situated outside a second turn (18, 20, 16) of the first track is greater than the width of the second turn of the first track.
  • b1 is greater than b2
  • b2 is greater than b3
  • b3 is greater than b4.
  • the magnitude of a surface of a cross section of at least a first part of the first track is greater than the magnitude of a surface of a cross section of at any rate at least a second part of the first track, while, in use, the current through the first part of the first track is greater than the current through the second part of the first track.
  • the first part of the first track can for instance be formed by, in this example, the outermost turn 14, while the second part of the first track is formed by the turn 18 situated within the turn 14. Also, in that case, the second part can be designated as the turn 20 or as the turn 16. It holds that the second part of the first track (e.g.
  • the turn 18 viewed in the direction 22 along the first track from an outermost turn to an innermost turn, is situated beyond the first part of the first track (here for instance the outermost turn 14).
  • the greatest current occurs through the tracks at the position A.
  • the current will gradually diminish in that it partly crosses from the first track to the second track. Because in those parts of the first track where the current is relatively great the width of the track is also relatively great, the ohmic losses are reduced, that is, reduced with respect to the situation where all tracks were to have the same width as that of the innermost turn 16.
  • the first part of the second track can for instance be the outermost turn 14 again, while the second part of the second track is for instance the turn 18 or 20 situated within turn 14, or the innermost turn 16 of the second track. Also, the first part of the second track can for instance be the turn 18 or 20 and the second part of the second track for instance the innermost turn 16. All other properties mentioned for the first track hold mutatis mutandis for the second track.
  • an RFID chip 42 is arranged between the free end 40 of the innermost turn 16 of the first track 4 and the free end 40 of the innermost turn 16 of the second track 8. It is furthermore possible that the dielectric situated between the free ends 40 of the innermost turns of the first and second tracks is provided with a weakening for deactivating the tag. This deactivation can then be done by introducing the tag into an electromagnetic interrogation field with a relatively large power.
  • the first and second track are conductively connected with each other at a position B of the innermost turns.
  • the greatest current occurs through the first and second track at the position B.
  • the turn 20 can for instance be less wide than the turn 16
  • the turn 18 can for instance be less wide than the turn 20
  • the turn 14 can for instance be less wide than the turn 18. Then this holds for both the turns of the first track and the turns of the second track. It holds then that, viewed in a direction along the first track from an innermost turn to an outermost turn, the magnitude of the surface of a cross section of the first track decreases.
EP20060076808 2005-09-30 2006-09-29 Resonanzetikett mit ausgeteilter Kapazität Expired - Fee Related EP1770666B1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL1030077A NL1030077C2 (nl) 2005-09-30 2005-09-30 Verbeterd resonantielabel met verdeelde capaciteit.

Publications (3)

Publication Number Publication Date
EP1770666A2 true EP1770666A2 (de) 2007-04-04
EP1770666A3 EP1770666A3 (de) 2008-03-12
EP1770666B1 EP1770666B1 (de) 2010-06-30

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP20060076808 Expired - Fee Related EP1770666B1 (de) 2005-09-30 2006-09-29 Resonanzetikett mit ausgeteilter Kapazität

Country Status (4)

Country Link
EP (1) EP1770666B1 (de)
CN (1) CN1945641B (de)
DE (1) DE602006015140D1 (de)
NL (1) NL1030077C2 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2498109B (en) * 2010-07-29 2015-01-28 Murata Manufacturing Co Resonant circuit and antenna device
GB2505577B (en) * 2011-06-13 2015-06-03 Murata Manufacturing Co Antenna device comprising a feed coil coupled to a coil antenna via a magnetic layer

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019133351A1 (en) * 2017-12-28 2019-07-04 Avery Dennison Retail Information Services, Llc Rfid tags using multi-layer constructions for improved durability

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4583099A (en) * 1983-12-27 1986-04-15 Polyonics Corporation Resonant tag circuits useful in electronic security systems
EP1107205A2 (de) * 1999-12-08 2001-06-13 Checkpoint Manufacturing Japan Co., Ltd. Resonanzetikett

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4598276A (en) * 1983-11-16 1986-07-01 Minnesota Mining And Manufacturing Company Distributed capacitance LC resonant circuit
NL9202067A (nl) * 1992-11-27 1994-06-16 Dutch A & A Trading Bv Detectielabel.
WO1999008245A1 (en) * 1997-08-08 1999-02-18 Ird A/S Polymeric radio frequency resonant tags and method for manufacture

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4583099A (en) * 1983-12-27 1986-04-15 Polyonics Corporation Resonant tag circuits useful in electronic security systems
EP1107205A2 (de) * 1999-12-08 2001-06-13 Checkpoint Manufacturing Japan Co., Ltd. Resonanzetikett

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2498109B (en) * 2010-07-29 2015-01-28 Murata Manufacturing Co Resonant circuit and antenna device
US9048526B2 (en) 2010-07-29 2015-06-02 Murata Manufacturing Co., Ltd. Resonant circuit and antenna device
GB2505577B (en) * 2011-06-13 2015-06-03 Murata Manufacturing Co Antenna device comprising a feed coil coupled to a coil antenna via a magnetic layer

Also Published As

Publication number Publication date
NL1030077C2 (nl) 2007-04-02
CN1945641B (zh) 2011-08-31
CN1945641A (zh) 2007-04-11
EP1770666B1 (de) 2010-06-30
DE602006015140D1 (de) 2010-08-12
EP1770666A3 (de) 2008-03-12

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