• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    PG18249 SE ABSTRACT The present invention reIates to a coil comprising a winding (45). The winding comprises a multi-axiai cable with one shielding layer connected to ground. (Fig. 4)
    公开号:SE1050526A1
    申请号:SE1050526
    申请日:2010-05-26
    公开日:2011-11-27
    发明作者:Fredrik Ahrentorp；Jakob Blomgren；Christian Jonasson；Andrea Prieto-Astalan；Christer Johansson
    申请人:Imego Ab；
    IPC主号:
    专利说明:

    PG18249 SE ENHANCED COIL TECHNlCAL FlELD The present invention relates to coils in general and measurement coils in particular.
    BACKGROUND OF THE INVENTION Dynamic magnetic properties of a material can be measured by sweeping the frequencyof the measuring field and measure the magnetic response, i.e. (real and imaginary components of the AC susceptibility).
    WO 2007120095, for example, by the same applicant describes a device for detecting amagnetic response or changes in a magnetic response of at least one magnetic particle ina carrier fluid. The detection principle comprises measuring the magnetic particlescharacteristic rotation period, and the measurement involves measurement of a Brownianrelaxation in the carrier fluid under influence of an external pulsed magnetic field. Thedevice comprises an arrangement for generating the pulsed magnetic field and at leasttwo substantially identical detection coils connected in gradiometer coupling to detection electronics for measuring the frequency.
    When measuring the dynamic magnetic properties of a material, induction coil techniquesare often used. ln this case the AC susceptometer is based on the principle of induction,and consist of an excitation coil providing an alternating homogenous magnetic field around a detection coil system placed inside the excitation coil.
    A detection coil system in the form of a first order gradiometer coupling placed in thecenter of the excitation coil 110 is shown in Fig. 1. The detection coil system 100 isformed by positioning two well matched coils 120 and 130 with their length axis co-Iinearto the length axis of the excitation coil and coupled together so that the detection coil system detects the rate of the magnetic flux difference between the two coils.
    PG18249 SE SUMMARY OF THE INVENTION ln AC-susceptometry, it is often necessary to measure up to frequencies of several MHzto adequately establish the magnetic properties of a sample. This application describesmethods and components used for coil system of a high-frequency susceptometer (HF-AC susceptometer) of maximum measurement frequency up to 100 MHz, preferably atleast 10 MHz.
    Thus, the invention relates a coil comprising a carrier and a winding. The windingcomprises a multi-axial cable with one shielding layer connected to ground. The multi-axial cable may be coaxial or triaxial. Preferably, according to one embodiment, the coil isan excitation coil and/or detection coil in a coil system for susceptometry. The coil mayoperate in a frequency to 100 MHz, at least 10 MHz. ln one embodiment, a secondshielding layer of the cable is connected to a current source voltage. According to oneembodiment, one or several shielding layers of the multi-axial cable is divided in several sections, with each section directly connected to the ground.
    The invention also relates to a device for detecting a dynamic magnetic response orchanges in a dynamic magnetic response of a general magnetic material or at least onemagnetic particle in a carrier fluid. The detection comprises measuring the magneticparticles characteristic magnetic relaxation in the carrier fluid under influence of anexternal magnetic field. The device comprises means for generating the magnetic field, atleast two substantially identical detection coils connected in a gradiometer coupling todetection electronics for measuring the induced voltage that is dependent on the dynamicmagnetic properties of a sample in the detection coils. The excitation coil and and/or atleast one of detection coils comprise a winding and the winding comprises a multi-axialcable with one shielding layer connected to ground. The multi-axial cable may be coaxialor triaxial. The device may operate in a frequency up to 100 MHz, at least 10 MHz. Thesecond shielding layer may be connected to a current source voltage. The field may be sinusoidal magnetic field or a pulsed magnetic field.
    The invention also relates to method of calibrating a device as described earlier. Themethod comprising: a first step of measuring the system response with an empty sampleholder, a second step of computing difference in signal when the empty sample holder is in the first coil to when the sample holder is in the second coil, a third step of measuring PG18249 SE 3 the system with a sample containing a material with a known and preferably frequencyindependent AC magnetic susceptibility; calibrating the system based on said measurements with respect to the amplitude and phase changes due to the device.
    The invention also relates to method of calibrating a device as described earlier. Themethod comprising: measuring a signal with an excitation voltage applied, but noexcitation current present, as a background signal, subtracting said measured signal froma measurement signal to remove capacitive contributions to derive magnetic properties of the sample, and calibrating with respect to amplitude and phase changes due to device.
    BRlEF DESCRIPTION OF THE DRAWINGS ln the following, the invention will be described with reference to enclosed non-limitingexemplary drawings, in which: Fig. 1Fig. 2Fig. 3Fig. 4 is a schematic of a known excitation and detection coil system.is a cut through a coaxial cable,is a cut through a traxial cable, and is a schemtic coil system according to the invention.
    DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS ln coil design (excitation and detection coils as mentioned earlier), e.g. for ACsusceptometer applications, the parasitic capacitance of individual windings of the coilmust be taken into account. This capacitance, together with the coil inductance andresistance, determines the coil resonance frequency above which the inductive responsedecreases rapidly, thus the resonance frequency should preferably be higher than the maximum measurement frequency, The resonance frequency can be increased by o Decreasing the number of windingso increasing the space between windings ø Decreasing dielectric constant of the insulating material between the windings For each coil of the coil system of Fig. 1, the resonance frequency should be above themaximum measurement frequency of the AC susceptometer. However, there may still be resonances below the measurement frequency in the coil system due to parasitic PG18249 SE 4 capacitances between the excitation coil and detection coils. Furthermore, the balance ofthe two detection coils is affected by the dielectric properties of the sample being measured through the parasitic capacitance between detection coils.
    According to the invention, in order to reduce the parasitic capacitances, low capacitancecoaxial or multi-axial cable can be used as coil windings of the detection and/or excitation coil with its shield grounded at one end.
    A multi-axial cable in this context relates to a cable with a core conductor and one or several (>1) conductive shielding layers. ln one embodiment, the shie|d(s) of the multi-axial cable can be divided in multiplesections, with each section directly connected to the ground point in order to reduce the inductance of the shield-to-ground path.
    Fig. 2 illustrates a cut through a coaxial cable 20 comprising a core 21 of a conductingmaterial, an insulating layer 22, a conducting shielding layer 23 and an outer insulatinglayer 24. According to the invention the conducting shielding layer 23 is connected to ground 25.
    Fig. 3 illustrates a cut through a triaxial cable 30 comprising a core 31 of a conductingmaterial, an insulating layer 32, a conducting shielding layer 33, another insulating layer34, a second conducting shielding layer 36 and an outer insulating layer 37. According tothe invention, the excitation coil can be wound using triaxial cable with one end of theouter shield 36 connected to the signal ground 35, and one end of the inner shield 33 connected to the excitation current source voltage (guard) 38.
    Fig. 4 illustrates an embodiment of detection coil system 40, e.g. in accordance withabove mentioned WO 2007120095, but adapted to the present invention, in the form of afirst order gradiometer coupling placed in the center of the excitation coil 41. Thedetection coil system 40 is formed by positioning two well matched coils 42 and 43 withtheir length axis co-linear to the length axis of the excitation coil 41 and coupled togetherso that the detection coil system may detect the rate of the magnetic flux difference between the two coils.
    PG18249 SE 5 A portion of the excitation coil is illustrated enlarged (encircled area). ln this case, theexcitation coil 41 comprises a tubular housing 44 provided with a winding comprisingcoaxial cable 45. At one end the shielding of the coaxial cable is connected to signal ground.
    The detection coils 42 and 43 may also be provided with same type of windings as theexcitation coil 41. However, a mixture of, for example coaxial and triaxial cables may be used to as winding for separate coils. ldeally, without sample in the detection coils, the signal picked up from the detection coilsshould be zero if the detection coils are perfectly balanced. Nevertheless, there may stillbe an electrically coupled signal from excitation coil to detection coil present, even ifcoaxial cable has been used in all coils. ln the embodiment of the HF AC susceptometer,this unwanted signal can first be measured with no excitation current present, as a(capacitive) background signal, which later can be subtracted from measurement signal toderive the magnetic properties of the sample. The HF AC susceptometer is furthercalibrated with respect to amplitude and phase changes due to the instrument itself. Thetwo calibration procedures, background and amplitude and phase compensation is described below. ln one embodiment, the measurement of the unwanted signal may be done by placing arelay in the excitation coil circuit just before the ground point. The capacitive backgroundis analyzed by measuring the system response with the excitation output voltage on, butwith the relay open. ln this configuration no current will flow in the excitation coil, but anexcitation voltage will be present in the excitation coil. The response picked up by the detection coil gives information on the capacitive background. ln another embodiment, the system for measurements of the AC susceptibility of for instance a magnetic particle system may be calibrated by a two-step procedure: ln the first step, the system response is measured with an empty sample holder. Theeffect this measurement picks up is the difference in signal when the empty sample holderis in the upper coil to when the sample holder is in the lower coil. The difference isattributed to the dielectric properties of the sample holder and the mechanical arm moving the sample holder. The resulting (complex) voltage, Vb = VbRe + j*Vb'm, is a background PG18249 SE 6 signal which is subtracted from any measured signal in the subsequent measurements.The second step is performed with a sample containing a material with a known andpreferably frequency independent magnetic susceptibility, for instance a paramagneticmaterial such as DygOg. The calibration materials are chosen preferably to have afrequency independent susceptibility in the frequency range used in our sensor system.The value of the susceptibility of the calibration material should preferably be in the samerange as for the measured sample. The geometry and dimensions of the calibrationsample should preferably be the same as for the measurement samples, in order to getthe correct coupling factor in the detection coil(s). The measured voltage minus thebackground gives the (complex) voltage-to-susceptibility transfer factor, G = Xcæ / (Vca. -Vb).
    The frequency dependency of the gain and the phase between the applied excitation fieldand the magnetic response from the detection coil(s) is a major concern in construction ofa high bandwidth susceptometer. The frequency dependency of the gain and the phasebecomes strong at high frequencies, especially at frequencies close to the resonancefrequency of the detection coil(s) or the excitation coil. The gain and phase can alsobecome frequency dependent due to the properties of the excitation electronics and/or thedetection electronics. The measured sample data will become incorrect, especially at high frequencies, if these effects are not compensated for.
    The frequency dependency of the gain and the phase shift are compensated by means ofa routine similar to the calibration described above. The difference is that the twocalibration steps at many different frequencies are performed. Hence, the result is afrequency dependent background (complex) voltage Vb(f) and a (complex) frequencydependent voltage-to-susceptibility transfer factor, G(f) = Xca, (f)/ (VCaI (f)- Vb(f)) . Using afrequency independent reference sample (a sample with a constant Xca.) simplifies the second step in the compensation routine. ln the above description, the invention is described with reference to susceptometerapplications. However, the teachings of the invention may easily be employed for coils inother systems such as: magnetometers in which magnetic properties are measured,measuring external magnetic fields in MHz frequency region, e.g. in Magnetic Resonance lmagine (MRI) systems, etc.
    PG18249 SE 7 The invention is not limited te the described and iiiustrated embodiments and theteachings of the invention can be varied in a number of ways without departure from the scope of the invention as claimed in the attached ciaims.
    权利要求:
    Claims (16)
    [1] 1. The coil of claim 1, wherein said multi-axial cable is coaxial.
    [2] 2. The coil of claim 1, wherein said multi-axial cable is triaxial.
    [3] 3. The coil of according to any of proceeding claims, wherein said coil is an excitation coil in a coil system for susceptometry.
    [4] 4. The coil of according to any of proceeding claims, wherein said coil is a detection coil in a coil system for susceptometry.
    [5] 5. The coil of according to any of proceeding claims for operation in a frequency to100 MHz, at least 10 MHz.
    [6] 6. The coil of claim 3, wherein a second shielding layer is connected to a current source voltage.
    [7] 7. The coil of according to any of proceeding claims, wherein one or several shieldinglayers of said multi-axial cable is divided in several sections, with each section directly connected to the ground.
    [8] 8. A device for detecting a dynamic magnetic response or changes in a dynamicmagnetic response of a magnetic material or at least one magnetic particle in acarrier fluid, said detection comprising measuring said magnetic particle'scharacteristic magnetic relaxation in said carrier fluid under influence of anexternal magnetic field, said device comprising means for generating saidmagnetic field, at least two substantially identical detection coils connected in agradiometer coupling to detection electronics for measuring the induced voltagethat is dependent on the dynamic magnetic properties of a sample in the detectioncoils, characterized in that said excitation coil and and/or detection coils comprisea winding (45) and said winding comprises a multi-axial cable with at least one shielding layer connected to ground.
    [9] 9. PG18249 SE
    [10] 10.
    [11] 11.
    [12] 12.
    [13] 13.
    [14] 14.
    [15] 15.
    [16] 16. The device of claim 9, wherein said multi axial cable is coaxial. The device of claim9, wherein said muiti-axial cable is triaxial. The device according to any of proceeding ciaims for operation in a frequency to100 MHz, at least 10 MHz. The device of claim 11, wherein a second shielding layer is connected to a current source voltage. The device according to any of ciaims 9-13, wherein said field is sinusoidal magnetic field or a pulsed magnetic field, A method of calibrating a device according to any of ciaims 9-13, the methodcomprising: a first step of measuring the system response with an empty sample holder, a second step of computing difference in signal when the empty sample holder isin the first coil to when the sample holder is in the second coil, a third step of measuring the system with a sample containing a material with aknown and preferably frequency independent magnetic susceptibility; calibrating the system with respect to amplitude and phase changes due to the device itself.. A method of calibrating a device according to any of ciaims 9-13, the methodcomprising: measuring a signal with no excitation current present, as a background signal,subtracting said measured signal from a measurement signal to derive magneticproperties of the sample calibrating with respect to amplitude and phase changes due to device.
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US2104916A|1935-10-31|1938-01-11|Rca Corp|Constant radio frequency generator|
    GB827506A|1956-09-28|1960-02-03|Her Majesty S Principal Sec De|Radio-frequency transformers|
    US3662255A|1970-04-13|1972-05-09|Charles L Garrett|Apparatus for locating concealed or buried metal bodies and a stable inductor usable in such detectors|
    US3614618A|1970-05-06|1971-10-19|Ncr Co|Magnetic susceptibility tester|
    US5311125A|1992-03-18|1994-05-10|Lake Shore Cryotronics, Inc.|Magnetic property characterization system employing a single sensing coil arrangement to measure AC susceptibility and DC moment of a sample|
    US5675259A|1995-09-14|1997-10-07|The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration|Method and apparatus for measuring fluid flow|
    US6054856A|1998-04-01|2000-04-25|The United States Of America As Represented By The Secretary Of The Navy|Magnetic resonance detection coil that is immune to environmental noise|
    US6700397B2|2000-07-13|2004-03-02|The Micromanipulator Company, Inc.|Triaxial probe assembly|
    JP4055125B2|2002-12-24|2008-03-05|日本光電工業株式会社|Coaxial cable and transmission transformer using the same|
    EP1697755A1|2003-07-30|2006-09-06|Koninklijke Philips Electronics N.V.|On-chip magnetic sensor device with suppressed cross-talk|
    SE0600870L|2006-04-19|2007-08-21|Imego Ab|Detection device and method|
    TW200835463A|2006-12-27|2008-09-01|Koninkl Philips Electronics Nv|Method and apparatus for measuring fluid properties, including pH|
    JP5288462B2|2008-10-06|2013-09-11|国立大学法人大阪大学|Explosives, illegal drug inspection device, antenna coil and explosives, illegal drug inspection method|
    TWI403752B|2009-12-14|2013-08-01|Magqu Co Ltd|A device for measuring alternating current magnetic permeability and method of measuring the same|US20140218535A1|2011-09-21|2014-08-07|Magna Electronics Inc.|Vehicle vision system using image data transmission and power supply via a coaxial cable|
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    DE102012218609A1|2012-10-12|2014-04-17|Robert Bosch Gmbh|Magnetic field detection device and magnetic field detection method|
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    GB2536931B|2015-03-31|2020-03-11|Teledyne E2V Uk Ltd|A transformer|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE1050526A|SE534842C2|2010-05-26|2010-05-26|Coil comprising winding consisting of a multi-axial cable|SE1050526A| SE534842C2|2010-05-26|2010-05-26|Coil comprising winding consisting of a multi-axial cable|
    EP11786989.1A| EP2577337A1|2010-05-26|2011-05-20|Coil comprising a winding comprising a multi-axial cable|
    PCT/SE2011/050636| WO2011149413A1|2010-05-26|2011-05-20|Coil comprising a winding comprising a multi-axial cable|
    US13/699,079| US20130134964A1|2010-05-26|2011-05-20|Coil comprising a winding comprising a multi-axial cable|
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