EP0397755A4 - Magnetic field concentrator - Google Patents
Magnetic field concentratorInfo
- Publication number
- EP0397755A4 EP0397755A4 EP19890902008 EP89902008A EP0397755A4 EP 0397755 A4 EP0397755 A4 EP 0397755A4 EP 19890902008 EP19890902008 EP 19890902008 EP 89902008 A EP89902008 A EP 89902008A EP 0397755 A4 EP0397755 A4 EP 0397755A4
- Authority
- EP
- European Patent Office
- Prior art keywords
- concentrator
- receiver means
- regions
- region
- magnetic field
- 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.)
- Withdrawn
Links
- 230000005855 radiation Effects 0.000 claims abstract description 9
- 239000012141 concentrate Substances 0.000 claims abstract description 4
- 230000004907 flux Effects 0.000 claims description 42
- 229910052751 metal Inorganic materials 0.000 claims description 37
- 239000002184 metal Substances 0.000 claims description 37
- 239000003990 capacitor Substances 0.000 claims description 4
- 230000000694 effects Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 239000004411 aluminium Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000002939 deleterious effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000005670 electromagnetic radiation Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/52—Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure
- H01Q1/526—Electromagnetic shields
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q7/00—Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
- H01Q7/04—Screened antennas
Definitions
- the present invention relates to magnetic field concentration apparatus, particularly signal enhancement and/or apparatus for confining magnetic flux within an aperture, and/or to shield magnetic flux from components, and/or to means for improving signal reception.
- the present invention has a particular application to passive devices, such as tokens, transponders or smart cards. 10 PRIOR ART
- metal placed in the proximity of a magnetic field receiving coil will substantially reduce the amount of magnetic field received by the coil.
- metal placed between a source of the magnetic field ⁇ and the coil can operate to prevent any magnetic field from being picked up by the coil as shown in Figure 1.
- the metal sheet serves to absorb and deflect the flux radiated from the driver coil or magnetic field source.
- Figure 2 shows another situation where a metal 20 sheet serves to reduce signal reception.
- the metal sheet is placed behind the coil.
- the metal sheet acts to reduce the amount of flux received by the coil by radiating an opposing flux field. The closer the metal sheet, to the coil, the larger the opposing flux field and the less signal flux is -r received by the coil. In effect the metal sheets serve to proportionately nullify the driver coil radiated flux.
- U.S. Patent 4,373,163 discloses an electrostatic shield with an antenna loop therein ( Figure 1).
- the antenna is surrounded by a metal shield.
- the specification does not , n disclose a conductor plate proximate and in substantially the same plane as an antenna to enhance signal reception, in accordance with the present invention as will be described in more detail hereinafter.
- U.S. Patent 4,486,731 discloses a signal , enhancement apparatus in the form of a coil having magnetically permeable material disposed in overlapping relationship with a coil.
- the coil is influenced by strips 23 and 24 when the coil is oriented parallel to the direction of impinging flux (column 2, lines 23 to 41).
- U.S. Patent 4,486,731 relates to the problem of coil reception when the coil is in the same plane as the impinging flux, whereas the present invention relates to ⁇ increasing the reception of flux by a coil by providing a concentrator in juxtaposition to and in substantially the same plane as the coil.
- U.S. Patent 4,754,284 discloses an automobile antenna system for use in receiving high frequency bands in - - excess of 50 MHz.
- An object of the present invention is to provide a concentrator which can be associated or juxtaposed a coil without deleterious effect on the coil's ability to receive . f . signals or magnetic fields.
- Another object of the present invention is to provide improved concentrator performance.
- the present invention in one form provides a concentrator adapted to concentrate signals for reception by a receiver means, said concentrator comprising an
- the present invention further provides a magnetic field concentrator comprising an electrically conductive portion, said concentrator being orientated to receive a magnetic field and cause flux to be radiated from said portion, the concentrator being juxtaposed a receiver means,
- the electrically conductive portion is preferably made of metal, for example aluminium or copper.
- the present invention also provides a magnetic field concentrator adapted to surround a receiver means, the concentrator comprising a loop having first and second interconnected portions, wherein : the first portion has first and second regions, the first portion being continuous between said first and second regions, the first region being juxtaposed and spaced from said second region, the first portion being adapted to c surround said receiver means, the second portion having third and fourth regions, the second portion being continuous between said third and fourth regions, the third region being juxtaposed and spaced from said fourth region, the second portion being adapted to 10 substantially encircle said first portion, first and second interconnection portions, the . first interconnection portion being adapted to couple said first region to said third region, the second interconnection portion being adapted to couple said second jc region and said fourth region, the loop being formed in a continuous manner and having a space provided between said first and second interconnection portions.
- the concentrator described above may, upon being 2 Q incident with a magnetic field, have substantially no magnetic field pass between said first and second portions, the field being diverted through said first portion and incident said receiver means.
- the present invention also provides a magnetic 25 field concentrator adapted to enhance field reception by a receiver means, the concentrator being juxtaposed and adapted to influence said receiver means, wherein the concentrator comprises a metal portion adapted to substantially surround said receiver means in one plane, the 30 metal portion being further adapted to encircle the receiver means in the plane in a discontinuous manner, wherein, upon radiation by said field, the concentrator generates flux which is received by the receiver means in addition to said field. ,,.
- the present invention may provide a shield for alleviating radiation from magnetic fields within a predetermined area, the shield comprising a loop having first and second portions and third and fourth interconnecting portions, the first portion having first and second regions, the first portion being continuous between said first and second regions, the first region being substantially opposingly juxtaposed and spaced from said second region, the first portion substantially encircling said predetermined area, the second portion having third and fourth regions, being aligned with the first and second regions respectively, the second portion being continuous between said third and fourth regions, the third reg a ion being y substantially opposingly juxtaposed and spaced from said' fourth region, the second portion being adapted to substantially encircle said first portion, the first interconnection portion being adapted to couple said first and fourth regions and the second interconnecting portion being adapted to couple said second and third regions, wherein said magnetic fields are substantially excluded from the area bounded by the first portion.
- the portions of the shield and concentrators described above may in one form be substantially "C" shaped in configuration.
- the present invention also provides a shield for substantially eliminating magnetic field radiation from within a predetermined area comprising a first conductive portion substantially encompassing said area and a second conductive portion substantially encompassing and being spaced from said first portion, end regions of said first and second portions being coupled in an overlapping arrangement so as to form one continuous strip, whereby, upon radiation by a magnetic field, the field is substantially diverted from said area.
- the present invention may also provide a magnetic field concentrator which may be used to confine an alternating magnetic flux within an aperture and/or 5 concentrate a magnetic flux in a coil and/or shield components from the flux.
- the concentrator may be useful where a large coil for collecting flux is more expensive than a concentrator and smaller coil or where the coil size presents problems.
- the concentrator may preferably be made from a material with good electrical conductivity which thereby improves the concentrator's performance. The degree of conductivity may determine the amount of flux radiated from the concentrator. Non-magnetic or magnetic conductors may also be contemplated.
- FIGS 1 and 2 show prior art arrangements.
- FIGS. 3 to 14 show various exemplary (only) forms of concentrator according to the present invention.
- coil should be construed in a non-limiting way.
- the term “coil” may 5 include, for example, any signal receiving apparatus or magnetic field receptor as the present invention has many applications.
- shape of the metal herein described should not be limited to a particular configuration. The shape of metal is dependent on its 0 application or use.
- the terms "signal” or “signals” include within their scope any form of electromagnetic radiation.
- the signal may, for example, be a powering signal or a data or informational signal.
- Figure 3 shows a metal sheet placed in the same plane as the coil.
- the metal serves to increase the amount of flux, impinging the coil.
- the increase of flux on the coil due to the metal is inversely proportional to the spacing between the metal and the coil. 5
- Figure 4 shows a coil surrounded in the coil's plane by metal. As can be seen, the additional fluxes produced by circulating currents, opposes and reduces the applied currents. Accordingly, no flux enhancement is produced for the coil the metal surrounds.
- Figure 5 shows metal similar in shape to that previously mentioned, however, a slot or gap is provided in the metal so that the metal surrounds the coil in a discontinuous manner.
- the gap in the metal surrounding the coil causes the eddy currents (produced in response to impinging flux) to produce a field that serves to increase the flux impinging the coil.
- Figure 6 shows a concentrator similar to that -. hereinbefore described.
- the concentrator may be preferably constructed in two form ⁇ :-
- a slot or slots are cut from the hole out to the perimeter to alleviate circulating currents, which causes a drastic reduction in flux, from encircling the hole.
- the slot(s) may overlap, as long as there is substantially no continuous conduction path around the central hole ( Figures 5, 6 and 7).
- Co-pending Applications PI 7198 ANTENNA STRUCTURE AND METHOD OF MANUFACTURE and PJ 1693 INDUCTIVE ELEMENT FOR USE AS AN ANTENNA IN TRANSPONDERS filed in the name of Magellan Corporation (Australia) Pty. Limited disclose a method of simultaneously fabricating electrical coils and capacitors. Conveniently, the plates of capacitors so fabricated may take a substantially "C" shaped configuration and be disposed to surround the associated coils as hereinbefore described. This technique permits the area consumed by said capacitor plates to contribute towards the flux gathering ability of said coils.
- a wire loop concentrator using high conductivity wire may perform the same concentrating function provided the wire forms a continuous conducting path.
- the operation of both exemplary forms as shown in the drawings can be described thus :- c
- Circulating currents induced on the surface of a metal plate prevent an alternating magnetic flux from penetrating below the skin depth. For lOOKHz on copper, this is about 0.18mm. Consequently, an alternating flux cannot penetrate thick metal , Q plates and flows around the conducting obstacle.
- the wire loop concentrator may also be used to substantially exclude flux from an area. By crossing the wire connections between the inner and outer loops, without allowing them to touch, the flux passing through the inner 3C . loop is drastically reduced.
- Figure 10 shows an example of this configuration.
- Figure 11 shows an example of a field concentrator acting as an electrostatic Faraday shield.
- the coil is - 8 - shown partially surrounded by a conventional Faraday shield.
- the Faraday shield is extended to form a field concentrator, or may be coupled to an existing concentrator.
- Electrostatic shielding reduces the capacitive sensitivity of the coil to objects in the vicinity of the coil.
- the Faraday shield may extend only part way around the coil in order to adjust capacitive sensitivity.
- field concentration and electrostatic shielding can be achieved using two field concentration plates. One placed in front of the coil, the other behind the coil as shown in Figure 12.
- Figure 13 shows a cross-section of this arrangement. Connection between the front and back plates can be made anywhere along the plates, however, preferably this is done on the inside and/or the outside of the coil. See Figures 14A, B and C.
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
- Near-Field Transmission Systems (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AUPI658188 | 1988-02-04 | ||
AU6581/88 | 1988-02-04 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0397755A1 EP0397755A1 (en) | 1990-11-22 |
EP0397755A4 true EP0397755A4 (en) | 1992-11-04 |
Family
ID=3772776
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19890902008 Withdrawn EP0397755A4 (en) | 1988-02-04 | 1989-02-03 | Magnetic field concentrator |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0397755A4 (en) |
JP (1) | JPH03503467A (en) |
CA (1) | CA1334215C (en) |
WO (1) | WO1989007347A1 (en) |
ZA (1) | ZA89872B (en) |
Families Citing this family (55)
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US5130697A (en) * | 1990-10-30 | 1992-07-14 | Sensormatic Electronics Corporation | Method and apparatus for shaping a magnetic field |
GB9220409D0 (en) * | 1992-09-28 | 1992-11-11 | Texas Instruments Holland | Shielded transponder |
US5557279A (en) * | 1993-09-28 | 1996-09-17 | Texas Instruments Incorporated | Unitarily-tuned transponder/shield assembly |
US5694139A (en) * | 1994-06-28 | 1997-12-02 | Sony Corporation | Short-distance communication antenna and methods of manufacturing and using the short-distance communication antenna |
JP3526928B2 (en) * | 1994-11-15 | 2004-05-17 | 株式会社ルネサスLsiデザイン | Non-contact IC card system |
JP4260917B2 (en) | 1998-03-31 | 2009-04-30 | 株式会社東芝 | Loop antenna |
JP2001168618A (en) * | 1999-12-08 | 2001-06-22 | Smart Card Technologies:Kk | Antenna device for reader/writer in non-contact type ic card system |
DE10149126A1 (en) * | 2001-10-05 | 2003-04-10 | Flexchip Ag | Production of a screen used for a transponder comprises applying ferromagnetic particles to a region of the substrate having the spatial expansion of the antenna structure of a transponder, aligning the ferromagnetic particles, etc. |
US7339120B2 (en) | 2003-06-26 | 2008-03-04 | Matsushita Electric Industrial Co., Ltd. | Electromagnetic wave shield |
JP2005102101A (en) * | 2003-09-01 | 2005-04-14 | Matsushita Electric Ind Co Ltd | Gate antenna device |
WO2007030862A1 (en) * | 2005-09-12 | 2007-03-22 | Magellan Technology Pty Ltd | An attenuation device for an antenna of an interrogator |
US9064198B2 (en) | 2006-04-26 | 2015-06-23 | Murata Manufacturing Co., Ltd. | Electromagnetic-coupling-module-attached article |
WO2009011423A1 (en) | 2007-07-18 | 2009-01-22 | Murata Manufacturing Co., Ltd. | Wireless ic device |
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WO2009145007A1 (en) | 2008-05-26 | 2009-12-03 | 株式会社村田製作所 | Wireless ic device system and method for authenticating wireless ic device |
JP5434920B2 (en) | 2008-08-19 | 2014-03-05 | 株式会社村田製作所 | Wireless IC device and manufacturing method thereof |
JP4605318B2 (en) | 2008-11-17 | 2011-01-05 | 株式会社村田製作所 | Antenna and wireless IC device |
CN102301528B (en) | 2009-01-30 | 2015-01-28 | 株式会社村田制作所 | Antenna and wireless ic device |
JP5510450B2 (en) | 2009-04-14 | 2014-06-04 | 株式会社村田製作所 | Wireless IC device |
CN103022661B (en) * | 2009-04-21 | 2014-12-03 | 株式会社村田制作所 | Antenna apparatus and resonant frequency setting method of same |
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JP5299518B2 (en) | 2009-11-04 | 2013-09-25 | 株式会社村田製作所 | Information processing system |
JP5652470B2 (en) | 2010-03-03 | 2015-01-14 | 株式会社村田製作所 | Wireless communication module and wireless communication device |
GB2491447B (en) | 2010-03-24 | 2014-10-22 | Murata Manufacturing Co | RFID system |
JP5630499B2 (en) | 2010-03-31 | 2014-11-26 | 株式会社村田製作所 | Antenna apparatus and wireless communication device |
JP5712506B2 (en) * | 2010-05-24 | 2015-05-07 | Tdk株式会社 | Proximity antenna and wireless communication device |
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JP5569648B2 (en) | 2011-05-16 | 2014-08-13 | 株式会社村田製作所 | Wireless IC device |
KR101338173B1 (en) | 2011-07-14 | 2013-12-06 | 가부시키가이샤 무라타 세이사쿠쇼 | Wireless communication device |
WO2013035821A1 (en) | 2011-09-09 | 2013-03-14 | 株式会社村田製作所 | Antenna device and wireless device |
CN103380432B (en) | 2011-12-01 | 2016-10-19 | 株式会社村田制作所 | Wireless IC device and manufacture method thereof |
JP5464307B2 (en) | 2012-02-24 | 2014-04-09 | 株式会社村田製作所 | ANTENNA DEVICE AND WIRELESS COMMUNICATION DEVICE |
JP5304975B1 (en) | 2012-04-13 | 2013-10-02 | 株式会社村田製作所 | RFID tag inspection method and inspection apparatus |
TWI474953B (en) * | 2012-05-23 | 2015-03-01 | Taiwan Lamination Ind Inc | Packaging bags with external stickers |
JP5964155B2 (en) * | 2012-06-28 | 2016-08-03 | Necトーキン株式会社 | Antenna device |
US11354558B2 (en) | 2013-01-18 | 2022-06-07 | Amatech Group Limited | Contactless smartcards with coupling frames |
US10476304B2 (en) | 2015-05-27 | 2019-11-12 | Qualcomm Incorporated | Wireless power receive coil for metal backed device |
JP7271162B2 (en) * | 2018-12-19 | 2023-05-11 | 株式会社ジャパンディスプレイ | Electronics |
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GB2014796A (en) * | 1978-02-17 | 1979-08-30 | Lichtblau G J | Antenna system for electronic security installation |
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JPS5843604A (en) * | 1981-09-09 | 1983-03-14 | Japan Radio Co Ltd | Antenna element |
US4549186A (en) * | 1982-04-14 | 1985-10-22 | Sensormatic Electronics Corporation | Coil assembly for substantially isotropic flux linkage in a given plane |
US4486731A (en) * | 1982-06-10 | 1984-12-04 | Sensormatic Electronics Corporation | Coil assembly with flux directing means |
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EP0242484A3 (en) * | 1986-04-23 | 1988-05-25 | Tektronix, Inc. | Electrical assembly having shielded structural sub-parts |
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-
1989
- 1989-02-03 WO PCT/AU1989/000036 patent/WO1989007347A1/en not_active Application Discontinuation
- 1989-02-03 JP JP1501854A patent/JPH03503467A/en active Pending
- 1989-02-03 EP EP19890902008 patent/EP0397755A4/en not_active Withdrawn
- 1989-02-03 ZA ZA89872A patent/ZA89872B/en unknown
- 1989-02-06 CA CA000590237A patent/CA1334215C/en not_active Expired - Fee Related
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
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GB2014796A (en) * | 1978-02-17 | 1979-08-30 | Lichtblau G J | Antenna system for electronic security installation |
Non-Patent Citations (2)
Title |
---|
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION vol. 34, no. 1, January 1985, NEW YORK US pages 111 - 114; DONALD E. BARRICK: 'Miniloop Antenna Operation and Equivalent Circuit' * |
See also references of WO8907347A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO1989007347A1 (en) | 1989-08-10 |
EP0397755A1 (en) | 1990-11-22 |
ZA89872B (en) | 1990-10-31 |
JPH03503467A (en) | 1991-08-01 |
CA1334215C (en) | 1995-01-31 |
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Legal Events
Date | Code | Title | Description |
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PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
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17P | Request for examination filed |
Effective date: 19900726 |
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AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AT BE CH DE FR GB IT LI LU NL SE |
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A4 | Supplementary search report drawn up and despatched |
Effective date: 19920911 |
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AK | Designated contracting states |
Kind code of ref document: A4 Designated state(s): AT BE CH DE FR GB IT LI LU NL SE |
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17Q | First examination report despatched |
Effective date: 19940207 |
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RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: MAGELLAN TECHNOLOGY PTY. LIMITED Owner name: THE UNIVERSITY OF WESTERN AUSTRALIA |
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STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
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18D | Application deemed to be withdrawn |
Effective date: 19951109 |