WO2022230032A1 - Coil set - Google Patents

Coil set Download PDF

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Publication number
WO2022230032A1
WO2022230032A1 PCT/JP2021/016693 JP2021016693W WO2022230032A1 WO 2022230032 A1 WO2022230032 A1 WO 2022230032A1 JP 2021016693 W JP2021016693 W JP 2021016693W WO 2022230032 A1 WO2022230032 A1 WO 2022230032A1
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Prior art keywords
coil
coils
receiving
receiving coil
array
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PCT/JP2021/016693
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French (fr)
Japanese (ja)
Inventor
慶一 野々垣
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株式会社ニレコ
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Priority to PCT/JP2021/016693 priority Critical patent/WO2022230032A1/en
Publication of WO2022230032A1 publication Critical patent/WO2022230032A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
    • G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
    • G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents

Definitions

  • the present invention supplies a standing wave sinusoidal current to an excitation coil to generate a primary magnetic field, induces eddy currents in the adjacent metal under test, and detects the secondary magnetic field returned from the eddy currents with a plurality of receiving coils.
  • a technique for detecting or measuring the presence/absence, position, distance, shape, and size of an object, or the presence/absence, position, distance, shape, and size of defects in an object is a technique for detecting or measuring the presence/absence, position, distance, shape, and size of an object, or the presence/absence, position, distance, shape, and size of defects in an object.
  • the disadvantage of the two-row staggered coil arrangement is that even if the presence or absence of scratches and their sizes can be known, since the coils and rows are spaced apart and arranged in a zigzag arrangement, it is not possible to recognize the shape of the scratches. Furthermore, the coil-to-coil distance and the row-to-row distance depend on the coil diameter, frequency, and required sensitivity. If the sensitivity is lowered, a staggered dead zone appears, and if the sensitivity is raised, interference occurs and the sensitivity cannot be varied. Moreover, when the frequency used is changed, the spatial magnetic field density distribution changes, so the sensitivity also changes. Therefore, the frequency also cannot be varied.
  • the two-row zigzag coil arrangement cannot obtain uniformity of detection ability over the entire length of the coil arrangement unless the frequency and sensitivity (exciting current and amplification factor) are appropriate for the coil diameter and coil spacing. If the frequency can be varied, the skin depth can be adjusted. Variable sensitivity allows the signal and disturbance to be matched to the optimum ratio for observation.
  • Patent Document 1 a method is disclosed in which the excitation coil group and the reception coil group are separated from each other, and the excitation coils are sequentially pulse-driven instead of simultaneously driving the excitation coils with a standing wave sinusoidal current. It is Since the excitation coils are periodically driven in sequence, no interference due to mutual induction occurs. In addition, since a single-row coil arrangement can be used instead of the two-row zigzag coil arrangement, it is possible to recognize the shape of a scratch.
  • the periodical driving of the exciting coils can maintain a uniform flaw detection capability if the moving speed of the inspection by the coil row (the moving direction is the direction perpendicular to the coil row) is intermittent, but if it moves at a constant speed, Homogeneity of detectability over the entire length of the coil sequence is lost. Since only a single excitation coil is driven at a given moment, the distance from that excitation coil to the receiving coil varies with the position of the receiving coil. The detection capability over the entire length of the coil sequence does not always remain homogeneous. The above are the limits of the use of multi-coil arrays in eddy current flaw detection.
  • a method using a plurality of coils is also disclosed for detecting the edge position of a metal strip whose distance varies.
  • the first coil detects both the edge and the distance of the metal strip
  • the second coil is placed directly under the inside of the metal strip and measures only the distance
  • the amplitude output of the first coil is measured.
  • the distance component is corrected using the amplitude output of the second coil to determine the edge position.
  • the "distance fluctuation-amplitude output characteristic” and the "edge position-amplitude output characteristic” do not match, so the edge position correction calculation according to the distance fluctuation is difficult, and calculation errors occur.
  • both characteristics change depending on the material (magnetic permeability, conductivity), thickness, frequency of use, coil diameter, and number of turns of the coil these variables must be taken into account in the correction calculation.
  • Patent Document 2 discloses an edge position measurement system that utilizes the edge detection characteristics of the coil.
  • the positional relationship between the edge and the coil there is a characteristic that when the edge reaches a specific position on the coil, the coil amplitude output becomes constant regardless of the distance.
  • the coil is moved by a mechanical slider so that the edge is always positioned at this distance-insensitive position, and the edge is followed so that it is positioned at this distance-insensitive position.
  • This method does not require correction calculations, and is not affected by changes in the material (magnetic permeability, conductivity), thickness, and frequency of use of the subject.
  • the reaction delay time is long, and if vibration occurs in the positional fluctuation of the edge, the vibration frequency causes control instability (oscillation).
  • a method of removing disturbance components other than edge position components from the amplitude output of the main coil using a correction coil has been disclosed in various places. This requires a large amount of data, and the relationship between parameters varies over many dimensions, making error evaluation difficult.
  • an excitation coil is arranged on one side of a passage through which a specimen passes, and a differential receiving coil is arranged on the opposite side, as in Patent Document 3.
  • the coil must have a large diameter, resulting in a large inductance.
  • the parallel resonance frequency which is the limit of the coil, decreases, and the detection sensitivity cannot be increased.
  • the larger the diameter of the coil the easier it is to pick up external noise and changes in the surrounding metal.
  • the amplification circuit was saturated by the metallic packaging material, and metallic foreign matter could not be detected.
  • DC magnetic field detection is commonly used, but it can only detect magnetic metals. It is better to be able to detect not only magnetic metallic foreign matter but also non-magnetic metallic foreign matter, even if the specimen contains metal.
  • the frequency and sensitivity are variable
  • the coil arrangement is in a row to recognize the flaw shape
  • the magnetic detection characteristics of each coil are always uniform over the entire length of the multi-coil array. is required.
  • it is required to be able to detect a wide range in real time, with high sensitivity and uniformity, and to be variable in frequency and sensitivity.
  • a multi-coil array with uniform magnetic detection characteristics can satisfy this requirement.
  • each receiving coil has a small diameter, the inductance is low, the frequency band can be increased, and high sensitivity can be achieved.
  • the small aperture results in a small detectable spatial area and low sensitivity to ambient spatial noise sources. If this small-diameter receiving coil is used as a multi-coil array, a wide area can be used as a high-sensitivity detection area, and low sensitivity can be maintained in the surrounding space.
  • a multi-coil array with equivalent magnetic detection characteristics using small-diameter receiving coils can detect the state of the magnetic field in real-time 1D, so a 2D planar magnetic field image can be acquired by scanning.
  • Fixed-shape incidental metal is observed as a known 2D magnetic field image pattern by scanning, and if there is foreign metal in a specimen having this incidental metal, it can be observed as a 2D magnetic field image in which the known 2D pattern is superimposed with a partial anomaly.
  • a multi-coil array with homogeneous magnetic detection characteristics can be used to capture the state of a magnetic field (whole shape and uneven deformation of each part) as a real-time 1D magnetic field image, just as a one-dimensional optical camera can project the shape and surface state of an object. can be done. Also, if two receiving coil arrays are used at different distances, a simple 3D magnetic field image can be obtained. Furthermore, with only a single exciting coil, the state of the exciting magnetic field and the magnetic flux density are different between the ends and the center of the exciting coil, and there is the problem that the magnetic detection characteristics of the receiving coil array cannot be homogenized.
  • the present invention provides a uniform magnetic flux density excitation coil structure that can obtain a flat magnetic flux density distribution, a receiving coil array with uniform magnetic detection characteristics, and a coil set that includes them.
  • the coil set of the present invention is basically composed of an exciting coil structure and one or more receiving coils, and the one or more receiving coils are arranged close to the exciting coil structure.
  • FIG. 1 shows a coil set according to the invention for use in a magnetic field measuring apparatus, comprising two receiver coil arrays 10 and an equal flux density excitation coil arrangement 20 .
  • the receiving coil 11 and the excitation coil are separate coils.
  • An electromotive force dependent on the interlinkage magnetic flux is generated in the receiving coil, and a coil current flows, which is very small in units of ⁇ A for AC magnetic field measurement applications.
  • the receiving coils 11 Since the receiving coils 11 have a small current regardless of whether they are close to each other or overlapped with each other, mutual induction can be almost ignored. Mutual induction does not occur in the coil arrays of the receiving coils 11 even if they are placed close to each other or overlapped. On the other hand, since the excitation coils pass a current of several tens of mA or more, mutual induction occurs when the excitation coils are formed into a coil array. Therefore, only the receiving coil 11 is a multi-coil array, and the exciting coil is a single structure having a size that covers the entire receiving coil array 10 .
  • the excitation coil arrangement is defined as an equal flux density excitation coil arrangement 20 .
  • the equal magnetic flux density excitation coil structure 20 consists of three excitation coils consisting of a top horizontal coil 21 and two side vertical coils 22 under both sides thereof. Each coil is rectangular. Each coil shown in FIG. 1 and subsequent drawings is simplified, and each excitation coil is bundled at the ends in the longitudinal direction of the coil and wired in parallel.
  • the receiving coil array 10 is composed of a plurality of receiving coils 11, all of which have the same shape. From the side surface of each receiving coil 11, the winding start and winding end of each receiving coil 11 are bundled and wired in parallel at a narrow pitch.
  • FIG. 2 is a side view of the constant magnetic flux density exciting coil assembly 20, and is a schematic diagram with polarities added.
  • the shape of the constant magnetic flux density excitation coil structure 20 is a U-shaped cross-sectional shape when viewed from the side. When the detection direction is upward, the U-shaped opening faces downward.
  • the equal magnetic flux density excitation coil structure 20 of the present invention may be of any structure shown in FIG.
  • FIG. 3 is a view showing a cross section of the magnetic field generated from the uniform magnetic flux density exciting coil structure 20, and the position of the uniform magnetic flux density exciting coil structure 20 is superimposed.
  • an excitation magnetic field cross section as shown in FIG. 3 is obtained, and the magnetic field spreads around the coil cross section position.
  • the electrical connection is such that the top horizontal coil 21 and the two side vertical coils 22 are also connected in parallel to reduce the combined inductance and thus the combined impedance so that a large excitation current can flow at both low voltage and high frequency.
  • the position of the receiving coil array 10 is set parallel to the plane of the top horizontal coil 21 of the uniform magnetic flux density excitation coil structure 20 and on the same longitudinal axis of symmetry.
  • the vertical direction is the short side direction of the rectangle of the top horizontal coil 21
  • the horizontal direction is the long side direction of the rectangle of the top horizontal coil 21 .
  • the vertical symmetry axes of the top horizontal coil 21 and the receiving coil array 10 are perpendicular to the dashed dotted line in FIG.
  • the receiving coil array 10 is placed on the same plane as the top horizontal coil 21 or is spaced above and below the top horizontal coil 21 so as to be parallel to the plane. There may be a plurality of receive coil arrays 10, and FIG.
  • FIG. 1 shows two receive coil arrays 10 and an equal flux density excitation coil arrangement 20.
  • the two receiving coil arrays 10 are positioned vertically parallel to each other, one receiving coil array 10 being positioned below the top horizontal coil 21 and the other above the top horizontal coil 21 in FIG. there is
  • FIG. 4 shows a horizontal direction of the receiving coil 11 with a small diameter parallel to the plane with the center of the vertical symmetry axis of the upper horizontal coil 21 as the exciting coil on the same plane as the coil surface of the upper horizontal coil 21 having a width of 300 mm. 2 shows an amplitude-voltage curve actually obtained by scanning .
  • the vertical axis of the graph in FIG. 4 represents the output voltage
  • the horizontal axis represents the position of the excitation coil. The same applies to the graphs up to FIG. 9 below.
  • FIG. FIG. 5 is a diagram in which the illustration of the magnetic flux density distribution in FIG. 4 and one top horizontal coil 21 are superimposed.
  • the magnetic flux density distribution obtained by one upper surface horizontal coil 21 has a concave distribution in which the magnetic flux density is high at both ends and the magnetic flux density is lowest at the center.
  • FIG. 6 shows the longitudinal direction when two side vertical coils 22 with a width of 300 mm are arranged in parallel, and the top horizontal coil 21 is arranged between the side vertical coils 22, which are exciting coils, on the top horizontal plane as shown in FIG. It represents an amplitude voltage curve actually obtained by horizontally scanning the center of the axis of symmetry with the small-diameter receiving coil 11 .
  • FIG. 6 shows the horizontal magnetic flux density distribution of the two side vertical coils 22 .
  • FIG. 7 is a diagram in which the illustration of this and two side vertical coils 22 are superimposed.
  • the magnetic flux density distribution obtained by the two side-perpendicular coils 22 has a convex distribution in which the magnetic flux density is low at both ends and highest at the center.
  • FIG. 8 one upper surface horizontal coil 21 with a width of 300 mm and two side vertical coils 22 with a width of 300 mm are combined in parallel to form a U-shaped cross section, and a small diameter receiving coil 11 is arranged as an upper surface horizontal coil.
  • 21 shows an amplitude voltage curve actually obtained by horizontally scanning the center of the axis of vertical symmetry on the same plane as 21 .
  • FIG. 9 is a diagram in which the illustration of the magnetic flux density distribution in FIG.
  • the magnetic flux density distribution obtained by three exciting coils arranged in a U-shape has sharp convex peaks at both ends, but a flat magnetic flux density distribution is obtained over a central portion of about 170 mm excluding both ends.
  • the top horizontal coil 21 and the side vertical coil 22 In order to obtain a horizontally flat equal magnetic flux density area without inclination in the central part, the top horizontal coil 21 and the side vertical coil 22 must be completely parallel, completely symmetrical, and arranged at the same position in the horizontal direction. If there is an inclination between the coils, the central flat will be inclined. In order to obtain a completely flat uniform magnetic flux density region, the distance between the top horizontal coil 21 and the side vertical coil 22 and the magnitude of the current must be matched.
  • the magnetic field measuring device using the coil set of the present invention has a structure that allows fine adjustment of the alignment between the exciting coils and always maintains reliable position fixing.
  • the receiving coil array 10 is placed in the central flat portion of FIGS. They are also symmetrical about the axis of symmetry.
  • 10 and 11 are perspective views of an example in which the uniform magnetic flux density excitation coil structure 20 and the receiving coil array 10 are formed as substrates, respectively.
  • the receiving coil array 10 is etched on the receiving coil array substrate 12, the top horizontal coils 21 are etched on the top horizontal coil substrate 23, and the side vertical coils 22 are etched on the side vertical coil substrate 24, respectively.
  • the magnetic detection characteristics of the receiving coils 11 become the same without causing mutual induction between the receiving coils.
  • the equal magnetic flux density excitation coil structure 20 maintains a flat magnetic flux density distribution even if the frequency is changed or the excitation current is changed, so the magnetic detection characteristics of the receiving coils 11 also maintain the same.
  • the receiving coil 11 Since the receiving coil 11 is brought close to the exciting coil, the receiving coil 11 detects a strong primary magnetic field emitted from the exciting coil. In contrast, the secondary magnetic field returned from the eddy currents flowing in the distant metal strip is weak, so that only small changes can be detected. A method of canceling this strong primary magnetic field is required.
  • Magnetic field balance method As a method of canceling the primary magnetic field component, there is a differential coil method. The primary magnetic field component is canceled by balancing the flux linkages of the positive and negative receiving coils within the same excitation coil. When an object passes near the coils, the magnetic field balance between the coils is disrupted, and a magnetic flux linkage difference between the coils is output. As a demerit, it is very difficult to balance the positive and negative coils. Secondly, there is a method of using a separately prepared correction receiving coil apart from the detection receiving coil. The detection receive coil and the correction receive coil are directly connected.
  • Both the first method and the second method are directly connected to a single coil of opposite polarity paired with a single detection receiving coil.
  • the receiving coils 11 are multi-coil arrays, it is troublesome to prepare opposite polarity coils for each receiving coil 11 .
  • a single balanced receiving coil (also referred to as a correction receiving coil) is once received by an OPAMP and impedance-converted, and the received signals of the respective receiving coils 11 of the multi-coil array are also received by the OPAMP, impedance-converted, and both signals are are synthesized by the synthesis circuit in the next stage.
  • This allows a single balanced receive coil to be shared across all receive coils 11 of the multi-coil array. Only a single balanced receive coil cancels each primary magnetic field component of all receive coils 11 .
  • the primary magnetic field component can be canceled, that is, the balance signal can be shared.
  • FIG. 12 illustrates connections between the equal flux density excitation coil structure 20, the receiving coil array 10, and the respective circuit blocks.
  • One top horizontal coil 21 and two side vertical coils 22 of the equal magnetic flux density excitation coil structure 20, and the balance excitation coil are connected in parallel and connected to an excitation amplifier circuit including a current amplifier and a voltage amplifier to obtain a sine wave. It is connected to a DDS (Direct Digital Synthesizer) that generates wave signals.
  • the receiving coil array 10 is connected to an analog receiving amplifier circuit for each receiving coil, connected to a synthesizing circuit for synthesizing balanced received signals of the same polarity generated and amplified by the balanced excitation coils, and connected to an amplitude and phase extracting circuit.
  • the extraction circuit may be an analog circuit or a digital circuit including an AD converter.
  • the receiving amplifier circuits of all CHs amplify the signal with the same amplification factor to maintain the homogeneity of the received signal. Although only three receiving coils 11 of the receiving coil array 10 are shown in FIG. 12, the number of receiving coils 11 is not limited.
  • a balanced excitation coil and a balanced receive coil are placed in close proximity, and the balanced receive coil produces a signal of the same polarity as the detection receive coil.
  • the balanced receive coils are connected to an amplifier circuit dedicated to balance and connected to a synthesis circuit for each receive CH of the receive coil array 10 .
  • the signals of the balanced receive coils are distributed in parallel to multiple combining circuits. A gain is adjusted by a balance-only amplifier so that the combined signal becomes zero or a specified value. Therefore, no mechanical alignment of the coils is required. Gain adjustment may be manual or automatic.
  • the synthesis circuit does not use analog adder/subtractor circuits. Mutual interference between inputs and non-uniformity of input resistance are problems of analog adder/subtractor circuits. Therefore, an instrumentation amplifier is used. Both inputs have high input impedance, no interference between inputs, and uniform input resistance. Since the input impedance of the instrumentation amplifier that serves as the synthesis circuit is high, the output of the balance-only amplifier can be signal-divided to a plurality of synthesis circuits. If the phase of the received signal before the synthesizing circuit is out of phase with the phase of the balanced output signal, zero balance cannot be obtained. A low-pass filter or high-pass filter may be used, but the cutoff frequency is set so as not to shift the signal phase.
  • connection block diagram of FIG. 12 does not show a filter circuit such as a bandpass filter, it can have a bandpass filter. Since the present invention can vary the excitation frequency, it is preferable that the cutoff frequency of the receiving band-pass filter automatically follows the excitation frequency in accordance with the excitation frequency.
  • a 1D magnetic field image can be obtained by arranging the amplitude and phase of each coil CH obtained from the extraction circuit of each CH in the order of the coil CH row.
  • a 2D magnetic field image can be obtained by arranging the 1D magnetic field images sequentially according to the scanning step.
  • FIG. 13 is a schematic diagram showing an experimental method for edge position detection of a metal strip 40 whose distance varies.
  • a test receiving coil 13 with a width of 100 mm, a length of 30 mm, and 20 turns is mounted on the upper surface of the horizontal coil 21 of 3 mm.
  • the edges 41 of the metal strips 40 which are placed at three positions near the center of the body 20 in a plan view from the upper surface thereof and are kept at a constant distance at each receiving coil point, are moved laterally.
  • the distances from the upper surface of the constant magnetic flux density excitation coil structure 20 to the metal strip 40 are set to 35 mm, 45 mm, 55 mm, and 65 mm, and the edge 41 of the metal strip 40 is placed laterally from above the test receiving coil 13 . crossed over.
  • the positions of the three receiving coils 13 for testing were set at the center of the excitation coil, 40 mm from the center to the bright side (the side without the specimen) and 20 mm from the center to the dark side (the side that overlaps the specimen). 14, 15 and 16 show the experimental results obtained by superimposing the positions of the receiving coils 13 for testing.
  • the horizontal axis indicates the horizontal position of the edge
  • the vertical axis indicates the amplitude output voltage sensed by the receiving coil 13 for testing.
  • the edge position characteristics for the same amplitude output voltage are obtained.
  • FIG. 17 shows the amplitude output voltage when the test receiving coil 13 is placed in the center of the excitation coil and the metal strip is moved vertically while maintaining the same lateral position around the distance insensitive intersection point of the receiving coil. .
  • Each curve is the amplitude output voltage obtained by vertical movement at each lateral position of the metal strip.
  • the horizontal axis is the separation distance, and the vertical axis is the coil amplitude output voltage.
  • the distance-insensitive points obtained in FIGS. 14, 15 and 16 are replaced by substantially horizontal straight lines in FIG. 14, 15 and 16 show that the more inside the receiving coil than the distance insensitive intersection point, the larger the output curve change, which corresponds to a large output difference by distance on the left side. 14, 15 and 16 show a small change in the output curve when positioned outside the distance insensitive intersection point, which corresponds to a small difference in output by distance on the right side, indicating an overshoot. show.
  • the receiving coil array 10 is a coil array, it can observe a wide detection range in real time with high sensitivity and uniformity. Homogeneity is maintained even if the frequency, excitation current, and amplification factor are varied.
  • the use of two receiving coil arrays 10 enables edge position measurement that is not affected by changes in the sample material (conductivity, magnetic permeability) and sample thickness. Output correction for each material is not required.
  • two receiving coil arrays 10 are used to obtain a simple 3D magnetic field image, so the position, distance, shape and size of the metal object can be recognized.
  • defects on the surface of the metal structure are separated from disturbances such as metal unevenness on the surface from a 2D magnetic field image using one receiving coil array 10, and the position, size and size of the defect are determined.
  • the shape can be specified.
  • a 2D magnetic field image with a gentle undulating change can be obtained for surface unevenness such as a weld bead in both the 1D axis direction and the time axis direction.
  • the location, size and shape of weld cracks are known.
  • FIG. 4 is a perspective view of a coil set consisting of an equal magnetic flux density excitation coil structure and two upper and lower multi-receiver coil arrays;
  • FIG. 4 is a side view of a constant magnetic flux density excitation coil arrangement; It is a figure showing the magnetic field cross section which generate
  • FIG. 10 is an illustration of an amplitude output curve with a top horizontal coil;
  • FIG. 11 is a diagram of a top horizontal coil and amplitude output curve;
  • FIG. 10 is an illustration of amplitude output curves with two lateral vertical coils;
  • Fig. 2 is a diagram of two lateral vertical coils and an amplitude output curve;
  • FIG. 10 is an illustration of an amplitude output curve with a top horizontal coil
  • FIG. 11 is a diagram of a top horizontal coil and amplitude output curve
  • FIG. 10 is an illustration of amplitude output curves with two lateral vertical coils
  • FIG. 10 is an illustration of amplitude output curves from an equal flux density excitation coil arrangement consisting of a top horizontal coil and two side vertical coils.
  • FIG. 10 is a diagram of an equal flux density excitation coil configuration consisting of a top horizontal coil and two side vertical coils and amplitude output curves;
  • FIG. 10 is a perspective view of a boarded uniform magnetic flux density excitation coil structure and a multi-receiving coil array;
  • FIG. 10 is a perspective view of a boarded uniform magnetic flux density excitation coil structure and a multi-receiving coil array;
  • FIG. 3 is a block diagram of the coil configuration including the balancing coils and the excitation and receiving circuitry;
  • FIG. 10 is a diagram of an experimental method using edge position detection of a metal strip that varies in distance as an example;
  • Fig. 3 is a graph representing the amplitude output voltage sensed by the test receive coil (light side);
  • Fig. 3 is a graph representing the amplitude output voltage sensed by the test receive coil (center);
  • Fig. 3 is a graph representing the amplitude output voltage sensed by the test receive coil (dark side);
  • Fig. 10 is a graph showing the amplitude output voltage when the metal strip is moved vertically while maintaining the same lateral position, about the distance insensitive point of the test receive coil;
  • FIG. 3 is a coil arrangement diagram of a distance variation-free edge position detector using the coil set of the present invention;
  • FIG. 2 is a cross-sectional view of a distance variation free edge position detector
  • FIG. 11 is a perspective view of a distance variation free edge position detector
  • FIG. 4 is a diagram showing how eddy currents flow in a metal strip and current density distribution in a distance variation-free edge position detector.
  • Fig. 10 is a graph representing a receive coil amplitude output curve obtained from an actual metal strip edge movement in a distance variation free edge position detector;
  • FIG. 10 is a simulation diagram showing the received strength of the secondary magnetic field only due to two horizontal eddy currents;
  • FIG. 10 is a simulation diagram showing the reception intensity of a secondary magnetic field only due to edge eddy currents in the vertical direction;
  • FIG. 26 is a simulation diagram showing the reception intensity of the secondary magnetic field due to eddy currents, which is the sum of FIGS. 24 and 25;
  • FIG. 3 is a layout diagram of a receiving coil array lateral cross-section of the distance variation-free edge position detector;
  • FIG. 10 is a coil arrangement diagram when the receiving coil shape of the distance variation-free edge position detector is horizontally short and vertically long.
  • FIG. 10 is a coil arrangement diagram when the receiving coil shape is horizontally long and vertically short;
  • FIG. 10 is a simulation diagram showing reception intensity when the shape of the receiving coil is set horizontally and vertically long.
  • FIG. 10 is a simulation diagram showing reception intensity when the shape of the receiving coil is horizontally long and vertically short;
  • FIG. 10 is a simulation diagram showing reception intensity when the shape of the receiving coil is horizontally long and vertically short;
  • FIG. 10 is a simulation diagram showing distance-insensitive intersection accuracy when the shape of the receiving coil is 30 mm long and 30 mm wide.
  • FIG. 10 is a simulation diagram showing the distance-insensitive intersection accuracy when the shape of the receiving coil is 30 mm long and 120 mm wide.
  • FIG. 10 is a simulation diagram showing distance-insensitive intersection accuracy when the shape of the receiving coil is 30 mm long and 150 mm wide.
  • FIG. 10 is a simulation diagram showing reception intensity when the shape of the receiving coil has the optimum aspect ratio; It is a coil arrangement diagram of a wide metal foreign object detector.
  • FIG. 4 is a diagram showing the excitation magnetic field of a wide metal foreign object detector; It is a coil arrangement diagram of a metal structure inspection device. It is a coil arrangement diagram of a metal structure inspection device.
  • FIG. 18 is a first utilization form of the magnetic field measuring device using the coil set of the present invention, and is a layout diagram of the coil set of the distance fluctuation free edge position detector 100.
  • FIG. FIG. 19 shows a cross-sectional view of the distance variation free edge position detector 100.
  • FIG. 20 shows a perspective view of the distance variation free edge position detector 100 . Details of the distance variation free edge position detector 100 will be described later.
  • the first application form of the magnetic field measuring device using the coil set of the present invention relates to position detection of an edge 141 of a metal strip 140 whose distance varies.
  • the metal strip 140 moving between the rolls begins to vibrate up and down as it moves.
  • the distance variation-free edge position detector 100 accurately detects the position of the edge 141 while allowing the vertical vibration of the metal strip 140 .
  • the equal magnetic flux density excitation coil structure 120 consists of a top horizontal coil 121 and two side vertical coils 122 on both sides thereof.
  • the receiving coil array 110 is arranged in two vertical rows parallel to each other, one above the top horizontal coil 121 and the other below the top horizontal coil 121 on the same vertical symmetry axis as the top horizontal coil 121 . be done.
  • FIG. 21 is a diagram showing an algorithm for accurately detecting the position of the edge 141 while allowing vertical vibration of the metal strip 140.
  • FIG. A “specimen” in the drawing indicates the metal strip 140 .
  • a real edge 141 and a coil space are formed, and there are two upper and lower receiving coil arrays 110, and coils A, B, C, D and E are arranged at regular intervals.
  • coils A, B, C, D and E are arranged at regular intervals.
  • a case where the position of the edge 141 is at the A position and a case where it is at the B position are illustrated.
  • the vertical axis is the amplitude output of each coil
  • the horizontal axis is the position of the edge 141 of the metal strip 140
  • the metal strip 140 is at a long distance.
  • the amplitude output curve of each coil for medium range and short range.
  • the metal strip 140 has an output curve with a steep slope at a short distance, an output curve with a moderate slope at a medium distance, and an output curve with a small slope at a long distance, which are common to all coil outputs.
  • the output of the coil A is the highest, followed by the output of the coil B, then the output of the coil C, then the output of the coil D, and so on.
  • the lowest coil E output is obtained.
  • the edge position is the A position, the voltage of each coil is low when the metal strip 140 is at a medium distance, and when the metal strip 140 is at a long distance, but similarly, the coil outputs are arranged in the same order. .
  • edge position B a similar order of coil voltages is obtained. However, coil output A and coil output B, which are out of the coil and cannot obtain linearity, are excluded from the calculation.
  • the coil 21 represents the coil position and the coil amplitude output voltage characteristic in a calculation space where the vertical axis is the amplitude output of each coil and the horizontal axis is the position of each coil in order.
  • Coil positions and spacings are in units of meters, and the output voltage of each coil is plotted at locations spaced in meters according to the actual coil array order. The plot projects each coil output voltage obtained in the upper left graph onto the upper right graph.
  • the outputs of the coils B, C, and D similarly connect straight lines. Since there are two receiving coil arrays 110 at the same vertical position with different vertical distances, the points of intersection between the straight lines obtained from the respective receiving coil arrays 110 can be obtained. This intersection point may be a virtual edge position on the calculation space. Even if the edge position is the B position, a straight line is obtained in the same way, and an intersection point is obtained.
  • the difference between the virtual edge positions A and B in the calculation space is equal to the distance difference (in meters) between the edge positions in the actual space.
  • the first condition is that the detection characteristics of each coil of the receiving coil array 110 must be the same.
  • the second condition is that the edge position-output characteristic of each receiving coil must be linear.
  • the third condition is that the accuracy of the intersection point where the distance-dependent output characteristic lines of the edge position-output characteristics of each receiving coil intersect is high. That is, it is necessary that the points of intersection converge to one point as much as possible over a wide range of distances.
  • the first condition is experimentally proven in the section on the effect of the invention mentioned above.
  • FIG. 22 is a diagram showing how eddy currents flow in the metal strip 140 and the current density distribution when the receiving coil 111 is placed near the center of the exciting coil.
  • the excitation frequency is set sufficiently low so that the excitation magnetic field can weakly penetrate the metal strip 140, and the surface opposite to the excitation side of the metal strip 140 is scanned vertically and horizontally with a small receiving coil 111.
  • FIG. 23 is a graph showing an actual amplitude output curve of the receiving coil 111 obtained when the metal strip 140 is moved laterally so as to overlap with the receiving coil 111 with the coil configuration shown in FIG. . It can be seen that linearity is actually obtained between the widths of the receiving coil 111 in the graph.
  • the excitation of the constant magnetic flux density excitation coil structure 120 produces a strong eddy current density above the coil wire of the excitation coil.
  • Two laterally parallel eddy current lines correspond to this.
  • a strong longitudinal eddy current density is generated at the position of the edge 141 connecting the two parallel eddy current lines in the lateral direction, although not above the coil wire of the exciting coil.
  • a longitudinal edge eddy current line runs to edge 141 .
  • another longitudinal eddy current flows above the exciting coil, but it is far enough away from the receiving coil 111 (assuming the exciting coil lateral width is sufficiently long) and can be ignored.
  • the total amount of interlinkage magnetic flux is calculated and graphed.
  • the total amount of vertical component interlinkage magnetic flux is the amplitude output of the receiving coil 111 .
  • LD30mm is 30mm
  • LD45mm is 45mm
  • LD60mm is 60mm
  • LD75mm is 75mm.
  • the graph shows curved lines at the beginning and end of overlapping with the receiving coil 111, but changes linearly in the area overlapping with the receiving coil 111.
  • FIG. 25 shows the vertical component of the interlinkage of the receiving coil 111 of the magnetic field generated by the edge eddy current line, considering that only the edge eddy current line in the vertical direction moves as the edge 141 of the metal strip 140 moves.
  • the total amount of interlinkage magnetic flux is calculated and graphed. Peaks with different polarities are obtained at the beginning and end of the overlap. In FIG. 25, the graph becomes a linear region slightly inside both peaks.
  • the output curve of the receiving coil 111 becomes an S-shaped curve.
  • the receiving coil 111 is separated from the metal strip 140 by a certain distance, and linear changes occur due to changes in the incident angle of the interlinking magnetic flux to the receiving coil 111 and changes in the amount of interlinking magnetic flux.
  • FIG. 26 is a graph obtained by adding together FIGS. 24 and 25, and represents the amplitude output voltage of the receiving coil 111 by three eddy current lines, ie, two parallel eddy current lines in the horizontal direction and edge eddy current lines in the vertical direction. Approximately the same output line shape as the actual graphs 14, 15 and 16 obtained by moving the edge 141 of the metal strip 140 is obtained. A linear change is obtained in the receiving coil 111 .
  • three receiving coils 111 provided linear output coupling. However, it is difficult to recognize and extract linearity with only three receiving coils 111 . Therefore, as shown in FIG. 27, a receiving coil array 110 is used in which the width of the receiving coils 111 is widened to some extent and the overlapping pitch of the coils is narrowed.
  • Each receiving coil 111 has a vertical width of 30 mm, a horizontal width of 128 mm, and a pitch of 16 mm.
  • the receiving coils 111 are stacked using eight substrate layers. The 16 receive coils 111 are processed simultaneously to capture three regions of the output curve: the middle straight region, the overshoot region, and the undershoot region.
  • the width of the arrangement of the 16 receiving coils 111 is 240 mm between centers and 368 mm from end to end.
  • each receiving coil 111 has a coil address according to the order of arrangement, and an array of 16 consecutive receiving coils 111 also has an array address according to the order of arrangement.
  • the array address being processed is directly below the current edge 141 position, and as the edge 141 moves, the array address also moves. Since coil selection is based on electrical switching rather than mechanical movement, high-speed response is possible.
  • the intersection accuracy of the third condition requires that the intersection points of distance-insensitive intersection points converge to one point as much as possible over a wide range of distances. In order to obtain high position detection accuracy of the edge 141 over a wide distance variation range, it is preferable that the accuracy of the intersection of the third condition is high.
  • 28 and 29 are coil arrangement diagrams showing that the aspect ratios of the receiving coils 111 are different while the uniform magnetic flux density excitation coil structure 120 is the same. In FIG. 28, the vertical width of each receiving coil 111 is wider than the horizontal width and wider than the vertical width of the excitation coil, and the shape of the receiving coil 111 is made horizontal and vertical long. In FIG.
  • each receiving coil 111 is narrower than the horizontal width and narrower than the vertical width of the excitation coil, and the receiving coil shape is horizontal and vertical.
  • FIG. 30 shows an amplitude output curve obtained when the shape of the receiving coil 111 is horizontally short and vertically long.
  • FIG. 31 shows an amplitude output curve obtained when the shape of the receiving coil 111 is horizontally long and vertically short.
  • the vertical axis represents the amplitude output of the receiving coil 111
  • the horizontal axis represents the position of the edge 141 of the metal strip 140
  • the unit of 0.5 on the horizontal axis is 15 mm.
  • D30mm is 30mm
  • D45mm is 45mm
  • D60mm is 60mm
  • D75mm is 75mm.
  • FIG. 32 shows intersection points of distances around the intersection position when the exciting coil has a vertical width of 90 mm and the receiving coil 111 has a vertical width of 30 mm and a horizontal width of 30 mm.
  • FIG. 33 shows intersection points of distances around the intersection position when the exciting coil has a vertical width of 90 mm and the receiving coil 111 has a vertical width of 30 mm and a horizontal width of 120 mm.
  • the vertical axis is the amplitude output of the receiving coil 111
  • the horizontal axis is the position of the edge 141 of the metal strip 140
  • D30mm is 30mm
  • D45mm is 45mm
  • D60mm is 60mm
  • D75mm is 75mm.
  • the intersection point of D30 mm and D45 mm is on the right end, the intersection point of D45 mm and D60 mm is in the center, and the intersection point of D60 mm and D75 mm is on the left end.
  • the intersection point of D30 mm and D45 mm is almost at the center, and the intersection point of D45 mm, D60 mm and D75 mm is at the left end, and they almost overlap.
  • the intersection of D30 mm, D45 mm, and D60 mm is at the left end and almost overlaps, and the intersection of D60 mm and D75 mm is shifted to the right by about 1.5 mm.
  • the order of the intersection points is reversed from that in FIG. 32, and the difference in the distance between the intersection points increases.
  • the excitation coil has a vertical width of 90 mm and the receiving coil 111 has a vertical width of 30 mm
  • the crossing point converges on one point over a wider distance range when the horizontal width of the receiving coil 111 is around 120 mm. Since the mechanical mechanism for restricting the approach of the metal strip 140 is simple, rather than the crossing point shifting due to separation to the far side, the shift of the crossing point is recognized when approaching the near side, and the order of crossing points shown in FIG. 34 is not used.
  • FIG. 35 is a zoomed-out graph of the output curve of the receiving coil 111 with the excitation coil having a vertical width of 90 mm and the shape of the receiving coil 111 having an optimal aspect ratio of 30 mm ⁇ 120 mm. 30 mm. A straight line is obtained at the central portion, and it can be seen that the intersection accuracy is high.
  • the equal magnetic flux density excitation coil structure 120 consisting of one upper surface horizontal coil 121 and two side surface vertical coils 122, and two receiving coil arrays 110 are patterns wired on the substrate, respectively.
  • Each substrate is fixed to a fixed size ceramic alumina pipe 101 by a resin full screw 102 and a resin nut 103 .
  • the upper horizontal coil substrate 123 is fixed to the center beam surface of the H-shaped extruded member 104 .
  • the two side vertical coil substrates 124 are fixed to the SUS comb-shaped base 105 , and the SUS comb-shaped base 105 is fixed to the middle convex portion of the side surface of the H-shaped extruded member 104 .
  • the upper and lower receiving coil array substrates 112 are fixed on the upper horizontal coil substrate 123 . Positioning through holes are drilled on both sides of the exciting coil substrate, and positioning lines are silk-printed. The triangular tip of the resin positioning block enters the hole and is positioned and fixed so as to match the positioning line.
  • the receiving coil array substrate 112 is positioned at three points on the outer shape by three resin positioning blocks.
  • the H-shaped extruded material 104 is an aluminum alloy extruded material with low conductivity, and is used as an external case and as a positioning base.
  • the inner uneven surface of the upper wing is thickly coated with magnetic paint. It prevents the secondary magnetic field generated by the eddy current from interlinking with the receiving coil 111 .
  • the upper surface is closed with a resin lid 106 .
  • a control substrate 107 is fixed in the H-shaped bottom recess, and is closed with a bottom lid 108 made of sheet metal.
  • a hole for wiring is opened in the H-shaped central beam surface.
  • the position of the edge 141 can be measured with high accuracy while allowing a wide range of distance variation. Since the intersection of the linear characteristic outputs obtained from the two receiving coil arrays 110 with different distances is regarded as the position of the edge 141, the material (magnetic permeability, conductivity) and thickness of the metal strip 140 can be ignored. Correction calculation for each material is not required. Since the receiver coil 111 that is always processed is selected according to the position of the edge 141, no mechanical slider is required. Response speed is fast. There is an advantage that the gain can be changed.
  • FIG. 36 is a second usage form using the coil set of the present invention, and is a layout diagram of the coil set of the wide metal foreign object detector 200.
  • FIG. A second form of utilization using the coil set of the present invention relates to the detection of minute metal foreign matter.
  • the wide metal foreign object detector 200 has two coil sets of an equal magnetic flux density excitation coil structure 220 and a receiving coil array 210 arranged vertically facing each other, and a specimen 240 passes between them.
  • the receiving coil array 210 consists of a plurality of receiving coils 211
  • the equal magnetic flux density excitation coil structure 220 consists of a top horizontal coil 221 and two side vertical coils 222 .
  • FIG. 37 is a diagram showing the excitation magnetic field of the wide metal foreign object detector 200.
  • FIG. The polarities of the equal magnetic flux density excitation coil structure 220 are opposite in phase between the upper coil set and the lower coil set, and the magnetic fields of the opposite polarities are represented as shown in FIG. In the intermediate region between the upper coil set and the lower coil set, an exciting magnetic field with a high magnetic flux density is formed in which the direction of the magnetic flux is vertical.
  • the receiving coil arrays 210 are provided in each of the upper and lower coil sets, and are installed symmetrically on substantially the same plane as the upper horizontal coils 221 .
  • the vertical width of each receiving coil 211 is wider than the horizontal width of the receiving coil and wider than the vertical width of the excitation coil.
  • the eddy current loop flowing through the minute metal foreign matter is small according to its volume, and the secondary magnetic field generated from the eddy current is also condensed.
  • the magnetic flux density of the far-reaching secondary magnetic field is very low, but spreads out in all isotropic directions in space. In order to detect this weak but isotropically spreading secondary magnetic field, the receiving coil 211 having a wider vertical width can pick up more magnetic flux.
  • the metal foreign object detector 200 applies an exciting magnetic field with a high magnetic flux density to minute metals at a long distance, and widely detects secondary magnetic fields from thinly spreading minute metals.
  • each receiving coil 211 has a large vertical width, so the horizontal width is small, so the coil area can be kept small. Since the coil area is small, it maintains low sensitivity to noise from the surrounding space.
  • the balanced received signal in canceling the primary magnetic field can be adjusted electrically rather than mechanically, and can be shared across all detection receiving coils of the receiving coil array 210 .
  • each receiving coil has a small diameter, the inductance is low, the frequency band can be increased, and the sensitivity can be increased. In addition, since each receiving coil has a small diameter, it has low sensitivity to noise sources in the surrounding space. Long-distance detection can be obtained by increasing the vertical width of the exciting coil.
  • each coil signal of the upper receiving coil array 210a may be used as a balance signal and mixed with the signal of each coil of the lower receiving coil array 210b.
  • receive coil array 210a The receiving coils 211 as well as the exciting coils must be vertically aligned.
  • the signals are mixed between the corresponding upper and lower coils, and the signal components of the lid metal are mixed up and down. Canceled for each coil set. Even if the distances from the upper and lower coil sets to the respective metal lids are different, they may be balanced by adjusting the gain.
  • FIGS. 38 and 39 are arrangement diagrams of the coil set of the metallic structure inspection apparatus 300, which is the third usage mode using the coil set of the present invention.
  • a third application form using the coil set of the present invention relates to eddy current flaw detection of metal structures.
  • the metal structure inspection apparatus 300 scans the uniform magnetic flux density excitation coil structure 320 and the receiving coil array 310 along the welding line 341 in parallel with the metal structure surface 340 .
  • the receiving coil array 310 consists of a plurality of receiving coils 311
  • the equal magnetic flux density excitation coil structure 320 consists of a top horizontal coil 321 and two side vertical coils 322 .
  • two parallel eddy current lines are formed on the metal structure surface 340 at positions symmetrical to the two parallel eddy current lines of the excitation coil.
  • a secondary magnetic field is generated from the two parallel eddy current lines and interlinked at each receiving coil 311 of the receiving coil array 310 .
  • weld line 341 has an undulating surface
  • the resulting 1D receiving array signals are also obtained as an undulating signal array. If weld cracks 342 are present, the weld cracks impede the flow of eddy currents. Since no secondary magnetic field is generated at the location where the eddy current is obstructed, the receiving coil 311 corresponding to that location has a low signal level. Weld cracks 342 can be detected because weld cracks 342 have sharp peaks and valleys against unevenness 343 of the weld surface.
  • FIG. 39 shows a structure in which the equal magnetic flux density excitation coil structure 320 is formed along the curvature of the metal structure surface 350 and the adjacent surface having the same curvature. Because of the same curvature as the metal structure surface 350, each receive coil is equidistant from the metal structure surface 350 and the resulting 1D receive array signals have a flat signal array. Similar to FIG. 38, weld cracks 352 have sharp peaks and valleys with respect to unevenness 351 of the weld surface, so weld cracks can be detected.
  • the equal magnetic flux density excitation coil configuration in FIG. 37 has a sector shape, but if the metal structure surface 350 is a concave curved surface, it may have an inverted sector shape.
  • the coil set of the metal structure inspection device 300 is a 1D coil array, it can inspect a wide range without gaps, in real time, with high sensitivity, and with uniformity. Furthermore, frequency and sensitivity are variable. Surface irregularities 343 and 351 and flaws can be separated from the 1D magnetic field image, and the shape of the flaw can be recognized from the scanned 2D magnetic field image.
  • Receiving coil array 11 Receiving coil 12: Receiving coil array substrate 13: Receiving coil for test 20: Equal magnetic flux density excitation coil structure 21: Top horizontal coil 22: Side vertical coil 23: Top horizontal coil substrate 24: Side vertical Coil substrate 40: Metal strip 41: Edge 100: Distance change-free edge position detector 101: Ceramic alumina pipe 102: Resin full thread 103: Resin nut 104: H-shaped extruded material 105: SUS comb base 106: Resin lid 107 : Control board 108: Bottom cover 110: Receiving coil array 111: Receiving coil 112: Receiving coil array board 120: Equal magnetic flux density excitation coil structure 121: Top horizontal coil 122: Side vertical coil 123: Top horizontal coil board 124: Side Vertical Coil Board 140: Metal Strip 141: Edge 200: Metal Foreign Object Detector 210: Receiving Coil Array 211: Receiving Coil 220: Equal Flux Density Excitation Coil Structure 221: Top Horizontal Coil 222: Side Vertical Coil 240: Specific Application

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Abstract

This invention provides an equal-magnetic-flux-density excitation coil configuration that makes it possible to obtain a flat magnetic flux density distribution, a reception coil array having homogenous magnetic detection characteristics, and a coil set comprising the equal-magnetic-flux-density excitation coil configuration and reception coil array.　A coil set according to this invention comprises an excitation coil configuration 20 that comprises an upper horizontal coil 21 and two vertical side coils 22 that are disposed below both sides of the upper horizontal coil 21 and is such that the polarities of the two vertical side coils 22 are opposite and face each other and the upper horizontal coil 21 has the same polarity as the magnetic flux flowing upward from the two vertical side coils 22, and one or more reception coils 11, and is characterized in that the one or more reception coils 11 are disposed so as to be near the excitation coil configuration 20. A reception coil array 10 is obtained in the coil set of this invention from a multi-coil array of a plurality of the reception coils 11.

Description

コイルセットcoil set
　本発明は、定常波正弦電流を励磁コイルに供給して一次磁界を発生させ、近接する被検体金属に渦電流を誘導し、その渦電流から返される二次磁界を、複数の受信コイルで検出し、被検体の有無、位置、距離、形状、サイズ、又は被検体の欠陥の有無、位置、距離、形状、サイズを検出、又は測定する技術に関する。 The present invention supplies a standing wave sinusoidal current to an excitation coil to generate a primary magnetic field, induces eddy currents in the adjacent metal under test, and detects the secondary magnetic field returned from the eddy currents with a plurality of receiving coils. , a technique for detecting or measuring the presence/absence, position, distance, shape, and size of an object, or the presence/absence, position, distance, shape, and size of defects in an object.
　［マルチコイル渦電流探傷について］
　マルチコイルアレイは、渦電流探傷の分野で各種方式が開示されている。単一コイルで広い領域をカバーしようとすると、傷検出能力が低下してしまう。そこで、小さいコイルを複数並べることで、傷検出能力を低下させることなく広い範囲をカバーする。一般的なマルチコイルアレイの配列として、２列のコイル列を千鳥に配置した配列が開示されている。これは、コイルとコイルを近づける又は重ねると、相互誘導による干渉が生じてしまうので、利用するコイル径、利用周波数、必要感度に合わせて充分な距離を離間する。しかし、離間したものの、コイルとコイルの間に傷が通過すると、傷を見落としてしまう。そこで、２列の千鳥コイル配列にして、コイル間の不感域をなくす。 [About multi-coil eddy current testing]
Various types of multi-coil arrays have been disclosed in the field of eddy current flaw detection. Attempting to cover a large area with a single coil reduces the ability to detect flaws. Therefore, by arranging a plurality of small coils, a wide range can be covered without lowering the flaw detection capability. As an arrangement of a general multi-coil array, an arrangement in which two rows of coils are arranged in a staggered manner is disclosed. This is because if the coils are brought close to each other or overlapped, interference due to mutual induction will occur. However, even though the coils are spaced apart, if a flaw passes between the coils, the flaw is overlooked. Therefore, a staggered coil arrangement in two rows is used to eliminate the dead area between the coils.
　２列の千鳥コイル配列のデメリットは、傷の有無、大きさは分かっても、コイル間および列間が離間し、千鳥配列となっているので、傷の形状の認識まではできない。さらに、コイル間距離、列間距離は、利用するコイル径、周波数、必要感度に依存する。感度を低くすると、千鳥間の不感域が現れだし、感度を高くすると、干渉が生じだし、感度を可変することができない。また、利用周波数を変更すると、空間磁界密度分布が変わるので、感度も変わる。よって、周波数も同様、可変できない。２列千鳥コイル配列は、コイル径とコイル間隔に合った適切な周波数と感度（励磁電流と増幅率）でなければ、コイル配列全長にわたる検出能力の均質性が得られない。周波数が可変できれば、表皮深さが調節できる。感度が可変できれば、信号と外乱を観測に最適な比率へと合わせ込むことができる。 The disadvantage of the two-row staggered coil arrangement is that even if the presence or absence of scratches and their sizes can be known, since the coils and rows are spaced apart and arranged in a zigzag arrangement, it is not possible to recognize the shape of the scratches. Furthermore, the coil-to-coil distance and the row-to-row distance depend on the coil diameter, frequency, and required sensitivity. If the sensitivity is lowered, a staggered dead zone appears, and if the sensitivity is raised, interference occurs and the sensitivity cannot be varied. Moreover, when the frequency used is changed, the spatial magnetic field density distribution changes, so the sensitivity also changes. Therefore, the frequency also cannot be varied. The two-row zigzag coil arrangement cannot obtain uniformity of detection ability over the entire length of the coil arrangement unless the frequency and sensitivity (exciting current and amplification factor) are appropriate for the coil diameter and coil spacing. If the frequency can be varied, the skin depth can be adjusted. Variable sensitivity allows the signal and disturbance to be matched to the optimum ratio for observation.
　そこで、特許文献１に記載されているように、励磁コイル群と受信コイル群をそれぞれ分離し、励磁コイルを定常波正弦電流で同時駆動するのではなく、励磁コイルを順次パルス駆動させる方式が、開示されている。励磁コイルが周期的に順番に駆動されるので、相互誘導による干渉は生じない。また、２列千鳥コイル配列ではなく、１列のコイル配列にすることができるので、傷の形状認識が可能となる。しかし、励磁コイルの周期駆動は、コイル列による検査の移動速度（移動方向は、コイル列と垂直方向）が間欠送りであれば、均質な傷検出能力を保てるが、一定速度の移動となると、コイル配列全長にわたる検出能力の均質性は失われる。ある瞬間に単一の励磁コイルのみが駆動されるので、その励磁コイルから受信コイルまでの距離は、受信コイルの位置によって異なる。コイル配列全長にわたる検出能力が、常時均質性を維持するわけではない。以上が、渦電流探傷におけるマルチコイルアレイの利用上の限界であった。 Therefore, as described in Patent Document 1, a method is disclosed in which the excitation coil group and the reception coil group are separated from each other, and the excitation coils are sequentially pulse-driven instead of simultaneously driving the excitation coils with a standing wave sinusoidal current. It is Since the excitation coils are periodically driven in sequence, no interference due to mutual induction occurs. In addition, since a single-row coil arrangement can be used instead of the two-row zigzag coil arrangement, it is possible to recognize the shape of a scratch. However, the periodical driving of the exciting coils can maintain a uniform flaw detection capability if the moving speed of the inspection by the coil row (the moving direction is the direction perpendicular to the coil row) is intermittent, but if it moves at a constant speed, Homogeneity of detectability over the entire length of the coil sequence is lost. Since only a single excitation coil is driven at a given moment, the distance from that excitation coil to the receiving coil varies with the position of the receiving coil. The detection capability over the entire length of the coil sequence does not always remain homogeneous. The above are the limits of the use of multi-coil arrays in eddy current flaw detection.
　［エッジ位置検出について］
　距離変動する金属帯体のエッジ位置検出においても複数のコイルを利用する方式が開示されている。一つ目のコイルは、金属帯体のエッジと距離の両方を検出し、二つ目のコイルは、金属帯体の内部直下に据え置き、距離のみを計測し、一つ目のコイル振幅出力の距離成分を二つ目のコイルの振幅出力を使って補正し、エッジ位置を割り出す。実際には、”距離変動‐振幅出力特性”と”エッジ位置‐振幅出力特性”は、一致しないので、距離変動に合わせたエッジ位置補正演算は難解であり、演算誤差が生じる。さらに、被検体の材質（透磁率、導電率）、厚さ、利用周波数、コイル径、コイル巻き数によってどちらの特性も変わるので、これら変数を考慮した補正演算としなければならない。 [About edge position detection]
A method using a plurality of coils is also disclosed for detecting the edge position of a metal strip whose distance varies. The first coil detects both the edge and the distance of the metal strip, the second coil is placed directly under the inside of the metal strip and measures only the distance, and the amplitude output of the first coil is measured. The distance component is corrected using the amplitude output of the second coil to determine the edge position. Actually, the "distance fluctuation-amplitude output characteristic" and the "edge position-amplitude output characteristic" do not match, so the edge position correction calculation according to the distance fluctuation is difficult, and calculation errors occur. Furthermore, since both characteristics change depending on the material (magnetic permeability, conductivity), thickness, frequency of use, coil diameter, and number of turns of the coil, these variables must be taken into account in the correction calculation.
　エッジ位置検出器でも特許文献２では、コイルのエッジ検出特性を利用したエッジ位置測定システムが開示されている。エッジとコイルの位置関係において、エッジがコイル上のある特定位置にさしかかると、距離に無関係にコイル振幅出力が一定になるという特性がある。この特性を利用し、エッジがこの距離無感の位置に常に位置するように、コイルをメカニカルスライダーで移動させ、この距離無感の位置にエッジが位置するように追従させる。この方式であれば、補正演算が必要なく、被検体の材質（透磁率、導電率）、厚さ、利用周波数が変わっても、影響を受けない。しかし、コイルをスライダーで追従させるので、反応遅れ時間が大きく、エッジの位置変動に振動が生じると、その振動周波数により制御不安定（発振）が生じる。 Regarding the edge position detector, Patent Document 2 discloses an edge position measurement system that utilizes the edge detection characteristics of the coil. Regarding the positional relationship between the edge and the coil, there is a characteristic that when the edge reaches a specific position on the coil, the coil amplitude output becomes constant regardless of the distance. Using this characteristic, the coil is moved by a mechanical slider so that the edge is always positioned at this distance-insensitive position, and the edge is followed so that it is positioned at this distance-insensitive position. This method does not require correction calculations, and is not affected by changes in the material (magnetic permeability, conductivity), thickness, and frequency of use of the subject. However, since the coil is made to follow the slider, the reaction delay time is long, and if vibration occurs in the positional fluctuation of the edge, the vibration frequency causes control instability (oscillation).
　補正コイルを利用しメインコイルの振幅出力からエッジ位置成分以外の外乱成分を取り除く方法は、各所で開示されているが、被検体の材質（透磁率、導電率）、厚さ、利用周波数を変数として加味した補正演算を行わなければならず、多くのデータを必要とし、各パラメータ間の関係は多次元にわたって異なるので、複雑であり、誤差評価は難しい。 A method of removing disturbance components other than edge position components from the amplitude output of the main coil using a correction coil has been disclosed in various places. This requires a large amount of data, and the relationship between parameters varies over many dimensions, making error evaluation difficult.
　［金属異物検出について］
　一般的に、特許文献３のように検体を通す通路の片側に励磁コイル、反対側に差動式受信コイルが配置される。幅広の検体を通そうとすると、コイルを大口径にしなければならず、インダクタンスが大きくなる。微小金属異物の検出感度を高めるには利用周波数が高いほど良い。しかし、インダクタンスが大きくなると、コイル限界となる並列共振周波数が低くなり、検出感度を高く出来ない。また、コイルを大口径にするほど、外来ノイズや、周囲金属の変化を拾いやすくなってしまう。 [About metal foreign object detection]
Generally, an excitation coil is arranged on one side of a passage through which a specimen passes, and a differential receiving coil is arranged on the opposite side, as in Patent Document 3. If a wide sample is to be passed through, the coil must have a large diameter, resulting in a large inductance. The higher the frequency used, the better, in order to increase the detection sensitivity of minute metal foreign matter. However, when the inductance increases, the parallel resonance frequency, which is the limit of the coil, decreases, and the detection sensitivity cannot be increased. Also, the larger the diameter of the coil, the easier it is to pick up external noise and changes in the surrounding metal.
　また、アルミ蓋等の包装材金属を付帯する検体の金属異物検出において、交流磁界検出法では金属包材によって増幅回路が飽和し、金属異物が検出できなかった。直流磁界検出法が一般に利用されているが、磁性金属しか検出できない。金属を付帯する検体であっても、磁性金属異物だけでなく、非磁性金属異物も検出できた方がよい。 In addition, in the detection of metallic foreign matter in specimens with packaging metal such as aluminum lids, in the AC magnetic field detection method, the amplification circuit was saturated by the metallic packaging material, and metallic foreign matter could not be detected. DC magnetic field detection is commonly used, but it can only detect magnetic metals. It is better to be able to detect not only magnetic metallic foreign matter but also non-magnetic metallic foreign matter, even if the specimen contains metal.
特開２００２－２２１５１４号公報Japanese Patent Application Laid-Open No. 2002-221514 米国特許第５２７０６４６号明細書U.S. Pat. No. 5,270,646 特許第４１９８７１２号公報Japanese Patent No. 4198712
　［マルチコイル渦電流探傷について］
　複数のコイルを近接してアレイ状に並べると、コイル間の相互誘導から、中心部から両端部まで、それぞれ検出特性が異なる。この相互誘導による干渉を避けるため、コイル間隔を大きくし、２列の千鳥配列にする、又は、時分割励磁にすることが、提案されてきた。しかし、どちらも別の問題を生じさせている。 [About multi-coil eddy current testing]
When a plurality of coils are closely arranged in an array, mutual induction between the coils causes different detection characteristics from the center to both ends. In order to avoid interference due to this mutual induction, it has been proposed to increase the spacing of the coils, to arrange them in a two-row staggered arrangement, or to use time-division excitation. But both pose other problems.
　マルチコイルアレイを使った渦電流探傷では、周波数、感度が可変であり、傷形状を認識する為にコイル配列が一列であり、かつマルチコイルアレイ全長にわたって各コイルの磁気検出特性が常時均質であることが求められる。また、広い範囲を、リアルタイムに、高感度に、かつ均質に、検出できること、加えて、周波数および感度が可変であることが求められる。磁気検出特性が均質なマルチコイルアレイであれば、この要求を満たすことができる。 In eddy current flaw detection using a multi-coil array, the frequency and sensitivity are variable, the coil arrangement is in a row to recognize the flaw shape, and the magnetic detection characteristics of each coil are always uniform over the entire length of the multi-coil array. is required. In addition, it is required to be able to detect a wide range in real time, with high sensitivity and uniformity, and to be variable in frequency and sensitivity. A multi-coil array with uniform magnetic detection characteristics can satisfy this requirement.
　［エッジ位置検出について］
　距離変動を許容できる金属板材のエッジ位置検出では、被検体の材質（透磁率、導電率）、厚さ、利用周波数に影響されず、スライダーなどの移動装置を使用しない電気的な装置であることが求められる。また、距離変動が大きくてもエッジ位置は高精度に測定したい。 [About edge position detection]
For detecting the edge position of a metal plate that can tolerate distance fluctuations, it must be an electrical device that is not affected by the material (magnetic permeability, conductivity), thickness, and frequency of the subject, and that does not use a moving device such as a slider. is required. Also, it is desired to measure the edge position with high accuracy even if the distance variation is large.
　磁気検出特性が均質なマルチコイルアレイを同じ垂直位置で上下平行に２枚用いれば、距離変動を許容し、エッジ位置を測定できる。つまり金属帯体の距離と位置がわかる。この構成であれば、受信コイル間の相互誘導はなく、被検体の材質（透磁率、導電率）、厚さ、利用周波数に影響されず、メカニカルなスライダーを必要としない。 If two multi-coil arrays with uniform magnetic detection characteristics are used in parallel vertically at the same vertical position, it is possible to allow distance variation and measure the edge position. That is, the distance and position of the metal strip can be known. With this configuration, there is no mutual induction between the receiving coils, the material (magnetic permeability, conductivity) and thickness of the object to be inspected is not affected by the frequency used, and a mechanical slider is not required.
　［金属異物検出について］
　周辺に非磁性、磁性含め様々な金属からなる機械装置が近接し、様々な電気ノイズ源もあるので、周辺空間では低感度で限られた検出領域内でのみ高感度であることが求められる。検体によっては、開口幅の広く、又は、開口高さが高い検出領域が必要である。また、アルミ包装材等の金属を有する検体の金属異物検出において、付帯金属を無感とし、金属異物のみを検出することが求められる。 [About metal foreign object detection]
Mechanical devices made of various metals, including non-magnetic and magnetic, are in close proximity to the surrounding area, and there are various sources of electrical noise. Depending on the specimen, a detection area with a wide opening width or a high opening height is required. In addition, in the detection of metallic contaminants in specimens containing metals such as aluminum packaging materials, it is required to detect only metallic contaminants while rendering incidental metals insensitive.
　各受信コイルを小口径とすれば、インダクタンスも低く、周波数帯域を高くでき、高感度にできる。小口径なので、検出可能空間領域が小さく、周辺空間のノイズ源には低感度となる。この小径受信コイルをマルチコイルアレイとすれば、広いエリアを高感度検出領域とし、周辺空間では低感度を保つことができる。 If each receiving coil has a small diameter, the inductance is low, the frequency band can be increased, and high sensitivity can be achieved. The small aperture results in a small detectable spatial area and low sensitivity to ambient spatial noise sources. If this small-diameter receiving coil is used as a multi-coil array, a wide area can be used as a high-sensitivity detection area, and low sensitivity can be maintained in the surrounding space.
　小径受信コイルを用いる等価な磁気検出特性のマルチコイルアレイであれば、リアルタイム１Ｄで磁界の容態を検出できるので、スキャンによって２Ｄ平面状の磁界画像が取得できる。固定形状の付帯金属は、スキャンによって既知の２Ｄ磁界画像パターンとして観測され、この付帯金属を有する検体に異物金属があると、この既知の２Ｄパターンに部分異常が重なる２Ｄ磁界画像として観測できる。 A multi-coil array with equivalent magnetic detection characteristics using small-diameter receiving coils can detect the state of the magnetic field in real-time 1D, so a 2D planar magnetic field image can be acquired by scanning. Fixed-shape incidental metal is observed as a known 2D magnetic field image pattern by scanning, and if there is foreign metal in a specimen having this incidental metal, it can be observed as a 2D magnetic field image in which the known 2D pattern is superimposed with a partial anomaly.
　［マルチコイルアレイについて］
　周波数、感度、被検体の材質（導電率、透磁率）、および厚さから独立してコイル配列全長にわたり各コイルの検出能力が常時均質であれば、多くの用途でその効果が活用できる。一次元光学カメラが、被写体の形状や表面状態を映し出しように、磁気検出特性が均質なマルチコイルアレイであれば、磁界の容態（全容と各部分の凸凹変容）をリアルタイム１Ｄ磁界画像で捉えることができる。また、受信コイルアレイを、距離を違えて２枚用いれば、簡易３Ｄ磁界画像が得られる。さらに、単一の励磁コイルだけでは、励磁コイルの端部と中央部では、励磁磁界の容態、および磁束密度が異なり、受信コイルアレイの磁気検出特性を均質化できないという問題がある。 [About multi-coil array]
If the detection ability of each coil is always uniform over the entire length of the coil arrangement, independent of frequency, sensitivity, subject material (conductivity, permeability), and thickness, the effect can be utilized in many applications. A multi-coil array with homogeneous magnetic detection characteristics can be used to capture the state of a magnetic field (whole shape and uneven deformation of each part) as a real-time 1D magnetic field image, just as a one-dimensional optical camera can project the shape and surface state of an object. can be done. Also, if two receiving coil arrays are used at different distances, a simple 3D magnetic field image can be obtained. Furthermore, with only a single exciting coil, the state of the exciting magnetic field and the magnetic flux density are different between the ends and the center of the exciting coil, and there is the problem that the magnetic detection characteristics of the receiving coil array cannot be homogenized.
　本発明は、フラットな磁束密度分布が得られる等磁束密度励磁コイル構成体、磁気検出特性が均質な受信コイルアレイ、および、それらを備えるコイルセットを提供する。 The present invention provides a uniform magnetic flux density excitation coil structure that can obtain a flat magnetic flux density distribution, a receiving coil array with uniform magnetic detection characteristics, and a coil set that includes them.
　［等磁束密度励磁コイル構成］
　本発明のコイルセットは、励磁コイル構成体と、一つまたは複数の受信コイルを基本構成とし、一つまたは複数の受信コイルは、励磁コイル構成体に近接して配置される。図１は、磁界測定装置に用いる本発明のコイルセットであって、２つの受信コイルアレイ１０と等磁束密度励磁コイル構成体２０を表している。磁界測定装置が備える本発明のコイルセットは、受信コイル１１と励磁コイルをそれぞれ別コイルとする。受信コイルには、その鎖交磁束に依存する起電力が生じ、コイル電流が流れるが、交流磁界計測用途ではμＡ単位と大変小さい。受信コイル１１同士は、近接しても、重ね合わせても、電流が小さいので、相互誘導はほぼ無視できる。受信コイル１１によるコイルアレイは、近接しても、重ね合わせても、相互誘導は生じない。一方、励磁コイルは、数十ｍＡ以上の電流を流すので、励磁コイルをコイルアレイにすると相互誘導が生じてしまう。そこで、受信コイル１１のみをマルチコイルアレイとし、励磁コイルは、受信コイルアレイ１０全域にわたる大きさの単一構成体とする。しかし、単一の励磁コイルだけでは、励磁コイルの端部と中央部では、励磁磁界の容態、および磁束密度が異なり、受信コイルアレイ１０の磁気検出特性を均質化できない。本願においては、励磁コイルの構成体は、等磁束密度励磁コイル構成体２０と定義される。 [Construction of Equal Magnetic Flux Density Exciting Coil]
The coil set of the present invention is basically composed of an exciting coil structure and one or more receiving coils, and the one or more receiving coils are arranged close to the exciting coil structure. FIG. 1 shows a coil set according to the invention for use in a magnetic field measuring apparatus, comprising two receiver coil arrays 10 and an equal flux density excitation coil arrangement 20 . In the coil set of the present invention provided in the magnetic field measuring device, the receiving coil 11 and the excitation coil are separate coils. An electromotive force dependent on the interlinkage magnetic flux is generated in the receiving coil, and a coil current flows, which is very small in units of μA for AC magnetic field measurement applications. Since the receiving coils 11 have a small current regardless of whether they are close to each other or overlapped with each other, mutual induction can be almost ignored. Mutual induction does not occur in the coil arrays of the receiving coils 11 even if they are placed close to each other or overlapped. On the other hand, since the excitation coils pass a current of several tens of mA or more, mutual induction occurs when the excitation coils are formed into a coil array. Therefore, only the receiving coil 11 is a multi-coil array, and the exciting coil is a single structure having a size that covers the entire receiving coil array 10 . However, with only a single exciting coil, the state of the exciting magnetic field and the magnetic flux density are different between the ends and the center of the exciting coil, and the magnetic detection characteristics of the receiving coil array 10 cannot be homogenized. In the present application, the excitation coil arrangement is defined as an equal flux density excitation coil arrangement 20 .
　［構成］
　等磁束密度励磁コイル構成体２０は、上面水平コイル２１とその両側下に２つの側面垂直コイル２２からなる３個の励磁コイルからなる。各コイルは矩形としている。図１以下の各コイルは簡略化された描画としており、各励磁コイルはコイル長手方向の端で束ねられ、並行配線される。受信コイルアレイ１０は、複数の受信コイル１１からなり、全て同じ形状であり、各受信コイル１１の側面から、受信コイル１１毎に巻き始めと巻き終わりが束ねられ狭ピッチで並行配線される。 [Constitution]
The equal magnetic flux density excitation coil structure 20 consists of three excitation coils consisting of a top horizontal coil 21 and two side vertical coils 22 under both sides thereof. Each coil is rectangular. Each coil shown in FIG. 1 and subsequent drawings is simplified, and each excitation coil is bundled at the ends in the longitudinal direction of the coil and wired in parallel. The receiving coil array 10 is composed of a plurality of receiving coils 11, all of which have the same shape. From the side surface of each receiving coil 11, the winding start and winding end of each receiving coil 11 are bundled and wired in parallel at a narrow pitch.
　［構成の形状］
　図２は等磁束密度励磁コイル構成体２０の側面図であり、極性を付記した模式図である。等磁束密度励磁コイル構成体２０の形状は、側面視でコの字型の断面形状となる。検出方向を上とした場合、コの字の開口は下を向く。 [Configuration shape]
FIG. 2 is a side view of the constant magnetic flux density exciting coil assembly 20, and is a schematic diagram with polarities added. The shape of the constant magnetic flux density excitation coil structure 20 is a U-shaped cross-sectional shape when viewed from the side. When the detection direction is upward, the U-shaped opening faces downward.
　［コイル極性］
　図２のように、２個の側面垂直コイル２２の極性は、反対極性で互いに向き合い、上面水平コイル２１の極性は、２つの側面垂直コイル２２から上面に流れる磁束と同じ極性をとる。本発明の等磁束密度励磁コイル構成体２０は、図２のいずれの構成でもよい。図３は、等磁束密度励磁コイル構成体２０から発生する磁界断面を表す図であり、等磁束密度励磁コイル構成体２０の位置を重ね合わせている。等磁束密度励磁コイル構成体２０においては、図３のような励磁磁界断面が得られ、コイル断面位置を中心に磁界が広がっている。 [Coil polarity]
As shown in FIG. 2, the polarities of the two side vertical coils 22 face each other with opposite polarities, and the polarity of the top horizontal coil 21 has the same polarity as the magnetic flux flowing from the two side vertical coils 22 to the top. The equal magnetic flux density excitation coil structure 20 of the present invention may be of any structure shown in FIG. FIG. 3 is a view showing a cross section of the magnetic field generated from the uniform magnetic flux density exciting coil structure 20, and the position of the uniform magnetic flux density exciting coil structure 20 is superimposed. In the constant magnetic flux density excitation coil structure 20, an excitation magnetic field cross section as shown in FIG. 3 is obtained, and the magnetic field spreads around the coil cross section position.
　［電気接続］
　電気接続は、上面水平コイル２１、２個の側面垂直コイル２２とも並列接続とし、合成インダクタンスを小さくし、よって合成インピーダンスを低くし、低電圧でも高周波でも大きな励磁電流を流せられるようにする。 [Electrical connection]
The electrical connection is such that the top horizontal coil 21 and the two side vertical coils 22 are also connected in parallel to reduce the combined inductance and thus the combined impedance so that a large excitation current can flow at both low voltage and high frequency.
　［受信コイルアレイ位置］
　受信コイルアレイ１０の位置は、等磁束密度励磁コイル構成体２０の上面水平コイル２１の面と平行に、かつ、同一縦対称軸上に、据えられる。ここで、縦方向は上面水平コイル２１の矩形の短辺方向であり、横方向は上面水平コイル２１の矩形の長辺方向とする。上面水平コイル２１および受信コイルアレイ１０の縦対称軸は、図２の一点鎖線と直交する。受信コイルアレイ１０は、上面水平コイル２１と同一平面上又は、上面水平コイル２１の上下に離れて面平行となるように据えられる。受信コイルアレイ１０は複数でもよく、図１は、２つの受信コイルアレイ１０と等磁束密度励磁コイル構成体２０を表している。２つの受信コイルアレイ１０は、同じ垂直位置で上下平行に位置し、図１では、一方の受信コイルアレイ１０は、上面水平コイル２１の下に、他方は上面水平コイル２１の上に位置している。 [Receive coil array position]
The position of the receiving coil array 10 is set parallel to the plane of the top horizontal coil 21 of the uniform magnetic flux density excitation coil structure 20 and on the same longitudinal axis of symmetry. Here, the vertical direction is the short side direction of the rectangle of the top horizontal coil 21 , and the horizontal direction is the long side direction of the rectangle of the top horizontal coil 21 . The vertical symmetry axes of the top horizontal coil 21 and the receiving coil array 10 are perpendicular to the dashed dotted line in FIG. The receiving coil array 10 is placed on the same plane as the top horizontal coil 21 or is spaced above and below the top horizontal coil 21 so as to be parallel to the plane. There may be a plurality of receive coil arrays 10, and FIG. 1 shows two receive coil arrays 10 and an equal flux density excitation coil arrangement 20. FIG. The two receiving coil arrays 10 are positioned vertically parallel to each other, one receiving coil array 10 being positioned below the top horizontal coil 21 and the other above the top horizontal coil 21 in FIG. there is
　［等磁束密度励磁コイル構成の分析］
　図４は、１個の横幅３００ｍｍの上面水平コイル２１のコイル面と同一平面上で、励磁コイルである上面水平コイル２１の縦対称軸中心を、小口径の受信コイル１１を面平行に横方向にスキャンして実際に得られた振幅電圧曲線を表している。図４のグラフの縦軸は出力電圧、横軸は励磁コイルの位置を表す。以下、図９までのグラフも同様とする。この受信コイル１１の振幅出力電圧は、コイルの鎖交磁束によってもたらされるので、図４は、１個の上面水平コイル２１の横方向の磁束密度分布を表している。また、図５は、図４の磁束密度分布をイラスト化したものと１個の上面水平コイル２１を重ね合わせた図である。１個の上面水平コイル２１により得られる磁束密度分布は、両端で磁束密度が高く、中心で磁束密度が最も低い凹型分布をしている。 [Analysis of Equal Flux Density Exciting Coil Configuration]
FIG. 4 shows a horizontal direction of the receiving coil 11 with a small diameter parallel to the plane with the center of the vertical symmetry axis of the upper horizontal coil 21 as the exciting coil on the same plane as the coil surface of the upper horizontal coil 21 having a width of 300 mm. 2 shows an amplitude-voltage curve actually obtained by scanning . The vertical axis of the graph in FIG. 4 represents the output voltage, and the horizontal axis represents the position of the excitation coil. The same applies to the graphs up to FIG. 9 below. Since the amplitude output voltage of this receiving coil 11 is caused by the coil flux linkage, FIG. FIG. 5 is a diagram in which the illustration of the magnetic flux density distribution in FIG. 4 and one top horizontal coil 21 are superimposed. The magnetic flux density distribution obtained by one upper surface horizontal coil 21 has a concave distribution in which the magnetic flux density is high at both ends and the magnetic flux density is lowest at the center.
　図６は、２個の横幅３００ｍｍの側面垂直コイル２２を平行に並べ、上端水平面上で、励磁コイルである側面垂直コイル２２の間に上面水平コイル２１を図１のように配した場合の縦対称軸中心を、小口径の受信コイル１１を横方向にスキャンして実際に得られた振幅電圧曲線を表している。図６は、２個の側面垂直コイル２２の横方向の磁束密度分布を表している。また、図７は、これをイラストしたものと２個の側面垂直コイル２２を重ね合わせた図である。２個の側面垂直コイル２２により得られる磁束密度分布は、両端で磁束密度が低く、中心で磁束密度が最も高い凸型分布をしている。 FIG. 6 shows the longitudinal direction when two side vertical coils 22 with a width of 300 mm are arranged in parallel, and the top horizontal coil 21 is arranged between the side vertical coils 22, which are exciting coils, on the top horizontal plane as shown in FIG. It represents an amplitude voltage curve actually obtained by horizontally scanning the center of the axis of symmetry with the small-diameter receiving coil 11 . FIG. 6 shows the horizontal magnetic flux density distribution of the two side vertical coils 22 . Also, FIG. 7 is a diagram in which the illustration of this and two side vertical coils 22 are superimposed. The magnetic flux density distribution obtained by the two side-perpendicular coils 22 has a convex distribution in which the magnetic flux density is low at both ends and highest at the center.
　図８は、１個の横幅３００ｍｍの上面水平コイル２１と２個の横幅３００ｍｍの側面垂直コイル２２をコの字型断面になるように平行に組み合わせ、小口径の受信コイル１１を、上面水平コイル２１と同一平面上で、縦対称軸中心を面平行に横方向にスキャンして実際に得られた振幅電圧曲線を表している。また、図９は、図８の磁束密度分布をイラスト化したものと等磁束密度励磁コイル構成体２０を重ね合わせた図である。コの字型に配した３個の励磁コイルにより得られる磁束密度分布は、両端で鋭く凸ピークがあるものの、両端を除いた中央部およそ１７０ｍｍにわたってフラットな磁束密度分布が得られている。これは、両端を除いた中央部で等磁束密度の領域が得られていることを示している。このフラットな磁束密度分布は、上面励磁コイルから垂直方向に離れるほど領域は狭くなるが、フラットな水平面状等磁束密度は保たれる。また、等磁束密度励磁コイル構成体２０は、周波数を変更しても、励磁電流を変更しても、中央部のフラットな磁束密度分布を維持する。 In FIG. 8, one upper surface horizontal coil 21 with a width of 300 mm and two side vertical coils 22 with a width of 300 mm are combined in parallel to form a U-shaped cross section, and a small diameter receiving coil 11 is arranged as an upper surface horizontal coil. 21 shows an amplitude voltage curve actually obtained by horizontally scanning the center of the axis of vertical symmetry on the same plane as 21 . FIG. 9 is a diagram in which the illustration of the magnetic flux density distribution in FIG. The magnetic flux density distribution obtained by three exciting coils arranged in a U-shape has sharp convex peaks at both ends, but a flat magnetic flux density distribution is obtained over a central portion of about 170 mm excluding both ends. This indicates that a region of uniform magnetic flux density is obtained in the central portion excluding both ends. The area of this flat magnetic flux density distribution becomes narrower with increasing distance from the top exciting coil in the vertical direction, but the flat horizontal uniform magnetic flux density is maintained. Further, the uniform magnetic flux density exciting coil structure 20 maintains a flat magnetic flux density distribution in the central portion even if the frequency is changed or the exciting current is changed.
　中央部で傾斜が無く、水平フラットな等磁束密度領域を得るには、上面水平コイル２１と側面垂直コイル２２が、完全平行、完全左右対称、かつ、横方向同一位置に配置されなければならない。コイル間に傾きがあると、中央部のフラットが傾斜してしまう。完全フラットな等磁束密度領域を得るには、上面水平コイル２１と側面垂直コイル２２との距離、及び、電流の大きさも合わせ込まなければならない。本発明のコイルセットを用いる磁界測定装置は、励磁コイル間の位置合わせの微調整が可能で、確実な位置固定が常時維持される構造体とする。 In order to obtain a horizontally flat equal magnetic flux density area without inclination in the central part, the top horizontal coil 21 and the side vertical coil 22 must be completely parallel, completely symmetrical, and arranged at the same position in the horizontal direction. If there is an inclination between the coils, the central flat will be inclined. In order to obtain a completely flat uniform magnetic flux density region, the distance between the top horizontal coil 21 and the side vertical coil 22 and the magnitude of the current must be matched. The magnetic field measuring device using the coil set of the present invention has a structure that allows fine adjustment of the alignment between the exciting coils and always maintains reliable position fixing.
　［受信コイルアレイの配置］
　受信コイルアレイ１０は、図８および図９の中央部のフラット部分、即ち等磁束密度の領域に据えられ、上面水平コイル２１の面と平行に、等磁束密度励磁コイル構成体２０の縦方向左右対称軸を中心として同じく左右対称に位置する。図１０と図１１は、等磁束密度励磁コイル構成体２０と受信コイルアレイ１０をそれぞれ基板化した例の斜視図である。受信コイルアレイ基板１２に受信コイルアレイ１０が、上面水平コイル基板２３に上面水平コイル２１が、側面垂直コイル基板２４に側面垂直コイル２２がそれぞれエッチングされている。 [Arrangement of receiving coil array]
The receiving coil array 10 is placed in the central flat portion of FIGS. They are also symmetrical about the axis of symmetry. 10 and 11 are perspective views of an example in which the uniform magnetic flux density excitation coil structure 20 and the receiving coil array 10 are formed as substrates, respectively. The receiving coil array 10 is etched on the receiving coil array substrate 12, the top horizontal coils 21 are etched on the top horizontal coil substrate 23, and the side vertical coils 22 are etched on the side vertical coil substrate 24, respectively.
　［均質な磁気検出特性］
　励磁がなく受信コイルアレイ１０自体は、各受信コイル１１それぞれの鎖交磁束を感受するのみなので、相互誘導がなく、受信コイルアレイ１０は均質な磁気検出特性といえる。単一の励磁コイルでは、磁束密度がコイルの箇所毎に異なり、複数の励磁コイル間では、相互誘導が生じてしまう。しかし、励磁磁界の磁束密度分布が均質であれば、その励磁磁界に受信コイルアレイ１０を据えることで、各受信コイル１１の一次磁界鎖交が同一となり、磁気検出特性を均一にできる。受信コイルアレイ１０を等磁束密度励磁環境下に置くことで、受信コイル間の相互誘導が生じない、各受信コイル１１の磁気検出特性が同一になる。等磁束密度励磁コイル構成体２０は、周波数を変更しても、励磁電流を変更しても、フラットな磁束密度分布を維持するので、各受信コイル１１の磁気検出特性も等価を維持する。 [Homogeneous magnetic detection characteristics]
Since there is no excitation and the receiving coil array 10 itself only senses the interlinking magnetic flux of each receiving coil 11, there is no mutual induction and the receiving coil array 10 can be said to have homogeneous magnetic detection characteristics. In a single exciting coil, the magnetic flux density differs at each position of the coil, and mutual induction occurs between a plurality of exciting coils. However, if the magnetic flux density distribution of the exciting magnetic field is uniform, by placing the receiving coil array 10 in the exciting magnetic field, the primary magnetic field linkage of each receiving coil 11 becomes the same and the magnetic detection characteristics can be made uniform. By placing the receiving coil array 10 in an excitation environment of equal magnetic flux density, the magnetic detection characteristics of the receiving coils 11 become the same without causing mutual induction between the receiving coils. The equal magnetic flux density excitation coil structure 20 maintains a flat magnetic flux density distribution even if the frequency is changed or the excitation current is changed, so the magnetic detection characteristics of the receiving coils 11 also maintain the same.
　［一次磁界のキャンセル］
　受信コイル１１を励磁コイルに近接させることになるので、受信コイル１１は、励磁コイルから発せられる強い一次磁界を検出する。これに対し、離れた金属帯体に流れる渦電流から返される二次磁界は弱いので、わずかな変化しか捉えられないこととなる。この強い一次磁界をキャンセルさせる方法が必要となる。 [Cancellation of primary magnetic field]
Since the receiving coil 11 is brought close to the exciting coil, the receiving coil 11 detects a strong primary magnetic field emitted from the exciting coil. In contrast, the secondary magnetic field returned from the eddy currents flowing in the distant metal strip is weak, so that only small changes can be detected. A method of canceling this strong primary magnetic field is required.
　［磁界バランス方法］
　一次磁界成分をキャンセルする方法として第一に、差動コイル方式がある。一次磁界成分は、同一励磁コイル内で正と負の受信コイルの鎖交磁束をバランスさせることによってキャンセルされる。物体がコイル近傍を通過する等によってコイル間の磁界バランスが崩れ、コイル間の鎖交磁束差が出力される。デメリットとして、正負コイルのバランス位置合わせが大変難しい。第二に、検出受信コイルとは離れて、別に用意した補正受信コイルを用いる方法がある。検出受信コイルと補正受信コイルは、直接接続される。 [Magnetic field balance method]
As a method of canceling the primary magnetic field component, there is a differential coil method. The primary magnetic field component is canceled by balancing the flux linkages of the positive and negative receiving coils within the same excitation coil. When an object passes near the coils, the magnetic field balance between the coils is disrupted, and a magnetic flux linkage difference between the coils is output. As a demerit, it is very difficult to balance the positive and negative coils. Secondly, there is a method of using a separately prepared correction receiving coil apart from the detection receiving coil. The detection receive coil and the correction receive coil are directly connected.
　第一の方法も、第二の方法も、単一の検出受信コイルと対をなす反対極性の単一コイルと直接接続される。受信コイル１１をマルチコイルアレイとする当該特許技術では、受信コイル１１毎に反対極性コイルを用意することは、煩雑である。 Both the first method and the second method are directly connected to a single coil of opposite polarity paired with a single detection receiving coil. In the patented technology in which the receiving coils 11 are multi-coil arrays, it is troublesome to prepare opposite polarity coils for each receiving coil 11 .
　そこで、単一のバランス受信コイル（補正受信コイルとも言える）を一旦OPAMPで受けて、インピーダンス変換し、マルチコイルアレイの各受信コイル１１の受信信号もそれぞれOPAMPで受けて、インピーダンス変換し、両信号を次段の合成回路で合成する。これにより、マルチコイルアレイの全ての受信コイル１１に渡り、単一のバランス受信コイルが共有される。単一のバランス受信コイルのみで、全ての受信コイル１１の各一次磁界成分がキャンセルされる。 Therefore, a single balanced receiving coil (also referred to as a correction receiving coil) is once received by an OPAMP and impedance-converted, and the received signals of the respective receiving coils 11 of the multi-coil array are also received by the OPAMP, impedance-converted, and both signals are are synthesized by the synthesis circuit in the next stage. This allows a single balanced receive coil to be shared across all receive coils 11 of the multi-coil array. Only a single balanced receive coil cancels each primary magnetic field component of all receive coils 11 .
　マルチコイルアレイの各受信コイルの検出特性が均質であるから、一次磁界成分のキャンセル、すなわちバランス信号を共用できる。 　Since the detection characteristics of each receiving coil of the multi-coil array are uniform, the primary magnetic field component can be canceled, that is, the balance signal can be shared.
　［接続ブロック図］
　図１２は、等磁束密度励磁コイル構成体２０と受信コイルアレイ１０とそれぞれの回路ブロックとの接続を図示している。等磁束密度励磁コイル構成体２０の１個の上面水平コイル２１と２個の側面垂直コイル２２、およびバランス励磁コイルは、並列接続され、電流増幅器や電圧増幅器を含む励磁増幅回路に接続され、正弦波信号を生成するＤＤＳ（ダイレクトデジタルシンセサイザー）に接続される。受信コイルアレイ１０は、受信コイル毎にアナログ受信増幅回路に接続され、バランス励磁コイルで生成されかつ増幅された同極性のバランス受信信号と合成される合成回路に接続され、振幅と位相抽出回路に接続されて、受信コイル毎の振幅と位相が抽出される。抽出回路は、アナログ回路でもよく、ＡＤ変換器含めたデジタル回路でもよい。どのＣＨの受信増幅回路も等しい増幅率で信号増幅し、受信信号の均質性を保持する。図１２では受信コイルアレイ１０の受信コイル１１の数は３個しか記載していないが、受信コイル１１の数に制限はない。 [Connection block diagram]
FIG. 12 illustrates connections between the equal flux density excitation coil structure 20, the receiving coil array 10, and the respective circuit blocks. One top horizontal coil 21 and two side vertical coils 22 of the equal magnetic flux density excitation coil structure 20, and the balance excitation coil are connected in parallel and connected to an excitation amplifier circuit including a current amplifier and a voltage amplifier to obtain a sine wave. It is connected to a DDS (Direct Digital Synthesizer) that generates wave signals. The receiving coil array 10 is connected to an analog receiving amplifier circuit for each receiving coil, connected to a synthesizing circuit for synthesizing balanced received signals of the same polarity generated and amplified by the balanced excitation coils, and connected to an amplitude and phase extracting circuit. connected to extract the amplitude and phase for each receiving coil. The extraction circuit may be an analog circuit or a digital circuit including an AD converter. The receiving amplifier circuits of all CHs amplify the signal with the same amplification factor to maintain the homogeneity of the received signal. Although only three receiving coils 11 of the receiving coil array 10 are shown in FIG. 12, the number of receiving coils 11 is not limited.
　［バランス励磁コイルとバランス受信コイルによる一次磁界のキャンセル］
　図１２の構成では、バランス励磁コイルとバランス受信コイルが近接して配置され、バランス受信コイルは検出受信コイルと同極性の信号を生成する。バランス受信コイルは、バランス専用の増幅回路に接続され、受信コイルアレイ１０の各受信ＣＨの合成回路に接続される。バランス受信コイルの信号は、複数の合成回路に並列分配される。バランス専用増幅器で増幅率を調整し、合成信号がゼロ又は規定値になるように増幅率が調整される。従って、コイルのメカニカルな位置合わせは必要としない。増幅率調整は、手動でも自動でもよい。 [Cancellation of primary magnetic field by balanced excitation coil and balanced receiving coil]
In the configuration of FIG. 12, a balanced excitation coil and a balanced receive coil are placed in close proximity, and the balanced receive coil produces a signal of the same polarity as the detection receive coil. The balanced receive coils are connected to an amplifier circuit dedicated to balance and connected to a synthesis circuit for each receive CH of the receive coil array 10 . The signals of the balanced receive coils are distributed in parallel to multiple combining circuits. A gain is adjusted by a balance-only amplifier so that the combined signal becomes zero or a specified value. Therefore, no mechanical alignment of the coils is required. Gain adjustment may be manual or automatic.
　［合成回路］
　合成回路は、アナログ加減算回路を使用しない。アナログ加減算回路では、入力間の相互干渉、入力抵抗の不均質が問題となる。そこで、計装アンプが利用される。両入力とも高入力インピーダンスで、入力間干渉がなく、入力抵抗が均質。合成回路となる計装アンプの入力インピーダンスが高いので、バランス専用増幅器の出力を複数の合成回路へ信号分配できる。なお、合成回路前の受信信号の位相とバランス出力信号の位相がずれると、バランスゼロが得られなくなる。ローパスフィルター、ハイパスフィルターを利用してもよいが、信号位相をずらさない様に、カットオフ周波数が設定される。 [Synthetic circuit]
The synthesis circuit does not use analog adder/subtractor circuits. Mutual interference between inputs and non-uniformity of input resistance are problems of analog adder/subtractor circuits. Therefore, an instrumentation amplifier is used. Both inputs have high input impedance, no interference between inputs, and uniform input resistance. Since the input impedance of the instrumentation amplifier that serves as the synthesis circuit is high, the output of the balance-only amplifier can be signal-divided to a plurality of synthesis circuits. If the phase of the received signal before the synthesizing circuit is out of phase with the phase of the balanced output signal, zero balance cannot be obtained. A low-pass filter or high-pass filter may be used, but the cutoff frequency is set so as not to shift the signal phase.
　［電気処理］
　図１２の接続ブロック図には、バンドパスフィルター等のフィルター回路を記していないが、バンドパスフィルターを有することができる。本発明は、励磁周波数が可変できるので、受信用バンドパスフィルターのカットオフ周波数も励磁周波数に合わせて自動で追従することが好ましい。各ＣＨの抽出回路から得られた各コイルＣＨの振幅と位相は、コイルＣＨ列の順に並べれば、１Ｄ磁界画像が得られる。スキャンする場合、スキャンするステップに合わせて１Ｄ磁界画像を順次並べれば、２Ｄ磁界画像が得られる。 [Electrical treatment]
Although the connection block diagram of FIG. 12 does not show a filter circuit such as a bandpass filter, it can have a bandpass filter. Since the present invention can vary the excitation frequency, it is preferable that the cutoff frequency of the receiving band-pass filter automatically follows the excitation frequency in accordance with the excitation frequency. A 1D magnetic field image can be obtained by arranging the amplitude and phase of each coil CH obtained from the extraction circuit of each CH in the order of the coil CH row. When scanning, a 2D magnetic field image can be obtained by arranging the 1D magnetic field images sequentially according to the scanning step.
　［実証実験の方法］
　本発明の受信コイルアレイ１０は、等価な磁気検出特性が得られるはずである。図１３は、距離変動する金属帯体４０のエッジ位置検出を例にした実験の方法を模式図として表している。横幅３００ｍｍ、縦幅６０ｍｍの等磁束密度励磁コイル構成体２０の上面水平コイル２１の３ｍｍ上面に、横幅１００ｍｍ、縦幅３０ｍｍ、巻き数２０回のテスト用受信コイル１３が、等磁束密度励磁コイル構成体２０の上面からの平面視中央付近３か所にそれぞれ据えられ、各受信コイル地点で離間距離を一定にした金属帯体４０のエッジ４１を横方向に移動させる。 [Method of demonstration experiment]
The receiving coil array 10 of the present invention should provide equivalent magnetic detection characteristics. FIG. 13 is a schematic diagram showing an experimental method for edge position detection of a metal strip 40 whose distance varies. On the upper surface of the uniform magnetic flux density excitation coil structure 20 with a width of 300 mm and a height of 60 mm, a test receiving coil 13 with a width of 100 mm, a length of 30 mm, and 20 turns is mounted on the upper surface of the horizontal coil 21 of 3 mm. The edges 41 of the metal strips 40, which are placed at three positions near the center of the body 20 in a plan view from the upper surface thereof and are kept at a constant distance at each receiving coil point, are moved laterally.
　等磁束密度励磁コイル構成体２０の上面から金属帯体４０までの離間距離は、３５ｍｍ、４５ｍｍ、５５ｍｍ、６５ｍｍに設定され、金属帯体４０のエッジ４１をテスト用受信コイル１３の上方から横方向に横切らせた。３個のテスト用受信コイル１３の位置は、励磁コイル中心、中心から４０ｍｍ明側（検体がない側）へ、中心から２０ｍｍ暗側（検体にかかる側）とした。図１４、図１５および図１６は、得られた実験結果を、それぞれのテスト用受信コイル１３の位置を重ねて表している。いずれの図も、横軸はエッジの横方向位置、縦軸はテスト用受信コイル１３が感知した振幅出力電圧を示す。 The distances from the upper surface of the constant magnetic flux density excitation coil structure 20 to the metal strip 40 are set to 35 mm, 45 mm, 55 mm, and 65 mm, and the edge 41 of the metal strip 40 is placed laterally from above the test receiving coil 13 . crossed over. The positions of the three receiving coils 13 for testing were set at the center of the excitation coil, 40 mm from the center to the bright side (the side without the specimen) and 20 mm from the center to the dark side (the side that overlaps the specimen). 14, 15 and 16 show the experimental results obtained by superimposing the positions of the receiving coils 13 for testing. In both figures, the horizontal axis indicates the horizontal position of the edge, and the vertical axis indicates the amplitude output voltage sensed by the receiving coil 13 for testing.
　［実験結果］
　テスト用受信コイル１３の両端部のオーバーシュートとアンダーシュート大きさは、テスト用受信コイル１３の位置によって異なる。しかし、テスト用受信コイル１３の中央部において離間距離毎の傾斜直線は、テスト用受信コイル１３の位置が異なっても同じ傾斜角で同じ出力電圧を保っている。また、距離無感交点（距離別曲線が交わる交点）の受信コイルに対する位置は同じである。受信コイルの位置を違えても磁気検出特性は等価である。出力電圧のオーバーシュート曲線とアンダーシュート曲線を除く受信コイルの中間位置範囲内では、同一の振幅出力電圧に対するエッジ位置特性（同一直線であり、傾斜角、振幅出力値が同じ）が得られている。 [Experimental result]
The magnitude of the overshoot and undershoot at both ends of the receiving coil 13 for testing differs depending on the position of the receiving coil 13 for testing. However, in the central portion of the receiving coil 13 for testing, the inclined straight line for each separation distance maintains the same output voltage at the same angle of inclination even if the position of the receiving coil 13 for testing is different. In addition, the position of the distance-insensitive intersection point (the intersection point where the distance-dependent curves intersect) with respect to the receiving coil is the same. Even if the position of the receiving coil is changed, the magnetic detection characteristics are equivalent. Within the intermediate position range of the receiving coil excluding the overshoot curve and undershoot curve of the output voltage, the edge position characteristics for the same amplitude output voltage (the same straight line, the same tilt angle, and the same amplitude output value) are obtained. .
　図１７は、テスト用受信コイル１３を励磁コイル中心に置き、受信コイルの距離無感交点あたりにて、金属帯体を同じ横方向の位置を保ちながら垂直に移動したときの振幅出力電圧を表す。各曲線は、金属帯体の横方向の各位置での垂直移動によって得られた振幅出力電圧である。横軸は離間距離、縦軸はコイル振幅出力電圧である。図１４、図１５および図１６で得られた距離無感交点は、図１７ではほぼ水平の直線に置き換わることを示している。図１４、図１５および図１６は、距離無感交点より受信コイルの内側に位置するほど、大きな出力曲線変化となっており、左側での大きな距離別出力差に相当することを表す。また、図１４、図１５および図１６は、距離無感交点より外側に位置すると、小さな出力曲線変化となっており、右側での小さな距離別出力差に相当し、オーバーシュートの箇所にあたることを表す。 FIG. 17 shows the amplitude output voltage when the test receiving coil 13 is placed in the center of the excitation coil and the metal strip is moved vertically while maintaining the same lateral position around the distance insensitive intersection point of the receiving coil. . Each curve is the amplitude output voltage obtained by vertical movement at each lateral position of the metal strip. The horizontal axis is the separation distance, and the vertical axis is the coil amplitude output voltage. The distance-insensitive points obtained in FIGS. 14, 15 and 16 are replaced by substantially horizontal straight lines in FIG. 14, 15 and 16 show that the more inside the receiving coil than the distance insensitive intersection point, the larger the output curve change, which corresponds to a large output difference by distance on the left side. 14, 15 and 16 show a small change in the output curve when positioned outside the distance insensitive intersection point, which corresponds to a small difference in output by distance on the right side, indicating an overshoot. show.
　以上のことから、励磁と受信を別にし、受信コイルアレイ１０を、フラットな等磁束密度の励磁磁界領域に置くことで、磁気検出特性が均質なマルチコイルアレイが得られる。 From the above, by separating excitation and reception and placing the receiving coil array 10 in a flat excitation magnetic field region with equal magnetic flux density, a multi-coil array with uniform magnetic detection characteristics can be obtained.
　［利用上の効果１］
　受信コイルアレイ１０の受信コイル１１の数を増加してアレイ横幅を長くし、励磁コイル横幅を長くすれば、感度低下することなく幅広な検出領域が得られる。各受信コイル１１は小口径なので、インダクタンスも低く、周波数帯域を高くでき、高感度にできる。また、各受信コイル１１は小口径であることから、周辺空間のノイズ源に低感度である。励磁コイル縦幅を広げると、長距離検出が得られる。 [Usage effect 1]
By increasing the number of receiving coils 11 of the receiving coil array 10 to lengthen the horizontal width of the array and lengthening the horizontal width of the excitation coil, a wide detection area can be obtained without lowering the sensitivity. Since each receiving coil 11 has a small diameter, the inductance is low, the frequency band can be increased, and the sensitivity can be increased. Also, since each receiving coil 11 has a small diameter, it has low sensitivity to noise sources in the surrounding space. Long-distance detection can be obtained by increasing the vertical width of the exciting coil.
　［利用上の効果２］
　受信コイルアレイ１０は、コイルアレイでありながら、広い検出範囲をリアルタイムに、高感度に、均質に、観測できる。周波数、励磁電流、増幅率を可変しても均質性は維持される。 [Usage effect 2]
Although the receiving coil array 10 is a coil array, it can observe a wide detection range in real time with high sensitivity and uniformity. Homogeneity is maintained even if the frequency, excitation current, and amplification factor are varied.
　［利用上の効果３］
　受信コイルアレイ１０の磁気検出特性が均質なので、各受信コイルの一次磁界キャンセル、判定基準が共通化できる。回路構成が容易であり、補正演算を必要としない。 [Usage effect 3]
Since the magnetic detection characteristics of the receiving coil array 10 are uniform, the primary magnetic field cancellation of each receiving coil and the judgment criteria can be shared. The circuit configuration is easy and no correction calculation is required.
　［利用上の効果４］
　一ライン上にコイルアレイを並べるので、１Ｄ磁界画像が得られる。スキャンによって２Ｄ磁界画像が得られる。受信コイルアレイ１０を２個用いれば、簡易３Ｄ磁界画像が得られる。 [Usage effect 4]
Since the coil arrays are arranged on one line, a 1D magnetic field image can be obtained. A 2D magnetic field image is obtained by scanning. If two receiving coil arrays 10 are used, a simple 3D magnetic field image can be obtained.
　距離変動するエッジ位置検出では、２個の受信コイルアレイ１０を用いることで、検体材質（導電率、透磁率）、検体厚みが変わっても左右されないエッジ位置測定が可能となる。材質毎の出力補正は必要ない。 In edge position detection where the distance fluctuates, the use of two receiving coil arrays 10 enables edge position measurement that is not affected by changes in the sample material (conductivity, magnetic permeability) and sample thickness. Output correction for each material is not required.
　離れた金属体の特定では、２個の受信コイルアレイ１０を用いることで、簡易３Ｄ磁界画像が得られるので、金属体の位置、距離、形状およびサイズが認識される。 When specifying a distant metal object, two receiving coil arrays 10 are used to obtain a simple 3D magnetic field image, so the position, distance, shape and size of the metal object can be recognized.
　金属構造体の渦電流探傷では、１個の受信コイルアレイ１０を用いた２Ｄ磁界画像から、金属構造体表層の欠陥を表面上の金属凹凸などの外乱から分離し、欠陥の位置、大きさおよび形状が特定できる。溶接ビートなどの表面の凹凸は、１Ｄ軸方向にも、時間軸方向にも、なだらか波打ち変化の２Ｄ磁界画像が得られ、溶接割れなどは、大きく急峻なピーク波形の２Ｄ磁界画像が得られ、溶接割れの位置、大きさおよび形状が分かる。 In the eddy current flaw detection of a metal structure, defects on the surface of the metal structure are separated from disturbances such as metal unevenness on the surface from a 2D magnetic field image using one receiving coil array 10, and the position, size and size of the defect are determined. The shape can be specified. A 2D magnetic field image with a gentle undulating change can be obtained for surface unevenness such as a weld bead in both the 1D axis direction and the time axis direction. The location, size and shape of weld cracks are known.
　付帯金属を有する検体の異物金属検出では、既知の付帯金属の２Ｄ磁界画像パターンからの逸脱（部分異常が重なる）があるかどうかで観測できる。付帯金属と異物金属では、信号の大きさが格段に異なるが、小さなアナログ増幅率でＡＤ変換すれば、飽和することなく信号処理できる。ＡＤ変換器のデジタル変換精度が、微小金属異物検出の検出能力となる。また、付帯金属は、既知の２Ｄ磁界画像パターンであるので、同期とパターン電圧発生回路により付帯金属の信号をキャンセルしてもよい。 In the detection of foreign metals in specimens with incidental metals, it is possible to observe whether there is a deviation (overlapping partial abnormalities) from the known 2D magnetic field image pattern of incidental metals. Accompanying metals and foreign metals have significantly different signal magnitudes, but if AD conversion is performed with a small analog amplification factor, signal processing can be performed without saturation. The digital conversion accuracy of the AD converter is the detection capability of minute metal foreign matter detection. Also, since the accessory metal is a known 2D magnetic field image pattern, the signal of the accessory metal may be canceled by the synchronization and pattern voltage generation circuits.
等磁束密度励磁コイル構成体と上下２個のマルチ受信コイルアレイからなるコイルセットの斜視図である。FIG. 4 is a perspective view of a coil set consisting of an equal magnetic flux density excitation coil structure and two upper and lower multi-receiver coil arrays; 等磁束密度励磁コイル構成体の側面図である。FIG. 4 is a side view of a constant magnetic flux density excitation coil arrangement; 等磁束密度励磁コイル構成体から発生する磁界断面を表す図である。It is a figure showing the magnetic field cross section which generate|occur|produces from a uniform magnetic flux density excitation coil structure. 上面水平コイルによる振幅出力曲線の図である。FIG. 10 is an illustration of an amplitude output curve with a top horizontal coil; 上面水平コイルと振幅出力曲線の図である。FIG. 11 is a diagram of a top horizontal coil and amplitude output curve; ２個の側面垂直コイルよる振幅出力曲線の図である。FIG. 10 is an illustration of amplitude output curves with two lateral vertical coils; ２個の側面垂直コイルと振幅出力曲線の図である。Fig. 2 is a diagram of two lateral vertical coils and an amplitude output curve; 上面水平コイルと２個の側面垂直コイルからなる等磁束密度励磁コイル構成体による振幅出力曲線の図である。FIG. 10 is an illustration of amplitude output curves from an equal flux density excitation coil arrangement consisting of a top horizontal coil and two side vertical coils. 上面水平コイルと２個の側面垂直コイルからなる等磁束密度励磁コイル構成体と振幅出力曲線の図である。FIG. 10 is a diagram of an equal flux density excitation coil configuration consisting of a top horizontal coil and two side vertical coils and amplitude output curves; 基板化した等磁束密度励磁コイル構成体とマルチ受信コイルアレイの斜視図である。FIG. 10 is a perspective view of a boarded uniform magnetic flux density excitation coil structure and a multi-receiving coil array; 基板化した等磁束密度励磁コイル構成体とマルチ受信コイルアレイの斜視図である。FIG. 10 is a perspective view of a boarded uniform magnetic flux density excitation coil structure and a multi-receiving coil array; バランス用コイルを含むコイル構成と励磁および受信回路のブロック図である。FIG. 3 is a block diagram of the coil configuration including the balancing coils and the excitation and receiving circuitry; 距離変動する金属帯体のエッジ位置検出を例にした実験方法の図である。FIG. 10 is a diagram of an experimental method using edge position detection of a metal strip that varies in distance as an example; テスト用受信コイル（明側）が感知した振幅出力電圧を表すグラフである。Fig. 3 is a graph representing the amplitude output voltage sensed by the test receive coil (light side); テスト用受信コイル（中心）が感知した振幅出力電圧を表すグラフである。Fig. 3 is a graph representing the amplitude output voltage sensed by the test receive coil (center); テスト用受信コイル（暗側）が感知した振幅出力電圧を表すグラフである。Fig. 3 is a graph representing the amplitude output voltage sensed by the test receive coil (dark side); テスト用受信コイルの距離無感交点あたりにて、金属帯体を同じ横方向の位置を保ちながら垂直に移動したときの振幅出力電圧を表すグラフである。Fig. 10 is a graph showing the amplitude output voltage when the metal strip is moved vertically while maintaining the same lateral position, about the distance insensitive point of the test receive coil; 本発明のコイルセットを用いた距離変動フリーエッジ位置検出器のコイル配置図である。FIG. 3 is a coil arrangement diagram of a distance variation-free edge position detector using the coil set of the present invention; 距離変動フリーエッジ位置検出器の断面図である。FIG. 2 is a cross-sectional view of a distance variation free edge position detector; 距離変動フリーエッジ位置検出器の斜視図である。FIG. 11 is a perspective view of a distance variation free edge position detector; 距離変動フリーエッジ位置検出器のアルゴリズムである。Algorithm of distance variation free edge position detector. 距離変動フリーエッジ位置検出器における金属帯体に流れる渦電流の流れ方と電流密度分布を表す図である。FIG. 4 is a diagram showing how eddy currents flow in a metal strip and current density distribution in a distance variation-free edge position detector. 距離変動フリーエッジ位置検出器において、実際の金属帯体のエッジ移動から得られる受信コイルの振幅出力曲線を表すグラフである。Fig. 10 is a graph representing a receive coil amplitude output curve obtained from an actual metal strip edge movement in a distance variation free edge position detector; 二本の横方向の渦電流のみによる二次磁界の受信強度を表すシミュレーション図である。FIG. 10 is a simulation diagram showing the received strength of the secondary magnetic field only due to two horizontal eddy currents; 縦方向のエッジ渦電流のみによる二次磁界の受信強度を表すシミュレーション図である。FIG. 10 is a simulation diagram showing the reception intensity of a secondary magnetic field only due to edge eddy currents in the vertical direction; 図２４と図２５を足し合わせた渦電流による二次磁界の受信強度を表すシミュレーション図である。FIG. 26 is a simulation diagram showing the reception intensity of the secondary magnetic field due to eddy currents, which is the sum of FIGS. 24 and 25; 距離変動フリーエッジ位置検出器の受信コイルアレイ横方向断面の配置図である。FIG. 3 is a layout diagram of a receiving coil array lateral cross-section of the distance variation-free edge position detector; 距離変動フリーエッジ位置検出器の受信コイル形状を横短縦長にした場合のコイル配置図である。FIG. 10 is a coil arrangement diagram when the receiving coil shape of the distance variation-free edge position detector is horizontally short and vertically long. 受信コイル形状を横長縦短にした場合のコイル配置図である。FIG. 10 is a coil arrangement diagram when the receiving coil shape is horizontally long and vertically short; 受信コイル形状を横短縦長にした場合の受信強度を表すシミュレーション図である。FIG. 10 is a simulation diagram showing reception intensity when the shape of the receiving coil is set horizontally and vertically long. 受信コイル形状を横長縦短にした場合の受信強度を表すシミュレーション図である。FIG. 10 is a simulation diagram showing reception intensity when the shape of the receiving coil is horizontally long and vertically short; 受信コイル形状を縦３０ｍｍ横３０ｍｍとした場合の距離無感交点精度を表すシミュレーション図である。FIG. 10 is a simulation diagram showing distance-insensitive intersection accuracy when the shape of the receiving coil is 30 mm long and 30 mm wide. 受信コイル形状を縦３０ｍｍ横１２０ｍｍとした場合の距離無感交点精度を表すシミュレーション図である。FIG. 10 is a simulation diagram showing the distance-insensitive intersection accuracy when the shape of the receiving coil is 30 mm long and 120 mm wide. 受信コイル形状を縦３０ｍｍ横１５０ｍｍとした場合の距離無感交点精度を表すシミュレーション図である。FIG. 10 is a simulation diagram showing distance-insensitive intersection accuracy when the shape of the receiving coil is 30 mm long and 150 mm wide. 受信コイル形状を最適縦横比にした場合の受信強度を表すシミュレーション図である。FIG. 10 is a simulation diagram showing reception intensity when the shape of the receiving coil has the optimum aspect ratio; 幅広の金属異物検出器のコイル配置図である。It is a coil arrangement diagram of a wide metal foreign object detector. 幅広の金属異物検出器の励磁磁界を表す図である。FIG. 4 is a diagram showing the excitation magnetic field of a wide metal foreign object detector; 金属構造物検査装置のコイル配置図である。It is a coil arrangement diagram of a metal structure inspection device. 金属構造物検査装置のコイル配置図である。It is a coil arrangement diagram of a metal structure inspection device.
　図１８は、本発明のコイルセットを用いた磁界測定装置の第１の利用形態であり、距離変動フリーエッジ位置検出器１００のコイルセットの配置図である。図１９は、距離変動フリーエッジ位置検出器１００の断面図を示す。また、図２０は、距離変動フリーエッジ位置検出器１００の斜視図を示す。距離変動フリーエッジ位置検出器１００の細部については後述する。図１８に示すように、本発明のコイルセットを用いた磁界測定装置の第１の利用形態は、距離変動する金属帯体１４０のエッジ１４１の位置検出に関する。ロール間を移動する金属帯体１４０は、移動によって上下振動を始める。距離変動フリーエッジ位置検出器１００は、金属帯体１４０の上下振動を許容してエッジ１４１の位置を正確に検出する。 FIG. 18 is a first utilization form of the magnetic field measuring device using the coil set of the present invention, and is a layout diagram of the coil set of the distance fluctuation free edge position detector 100. FIG. FIG. 19 shows a cross-sectional view of the distance variation free edge position detector 100. FIG. Also, FIG. 20 shows a perspective view of the distance variation free edge position detector 100 . Details of the distance variation free edge position detector 100 will be described later. As shown in FIG. 18, the first application form of the magnetic field measuring device using the coil set of the present invention relates to position detection of an edge 141 of a metal strip 140 whose distance varies. The metal strip 140 moving between the rolls begins to vibrate up and down as it moves. The distance variation-free edge position detector 100 accurately detects the position of the edge 141 while allowing the vertical vibration of the metal strip 140 .
　距離変動フリーエッジ位置検出器１００では、図１８のように、金属帯体１４０の移動方向に対して鉛直方向に、金属帯体１４０の下方に、金属帯体１４０のエッジ１４１がかかるように、本発明のコイルセットを据える。等磁束密度励磁コイル構成体１２０は、上面水平コイル１２１とその両側下に２個の側面垂直コイル１２２からなる。受信コイルアレイ１１０は面平行に同じ垂直位置に上下２列あり、一方は上面水平コイル１２１の上側に、もう一方は上面水平コイル１２１の下側に上面水平コイル１２１と同一縦対称軸上に据えられる。 In the distance variation-free edge position detector 100, as shown in FIG. Install the coil set of the present invention. The equal magnetic flux density excitation coil structure 120 consists of a top horizontal coil 121 and two side vertical coils 122 on both sides thereof. The receiving coil array 110 is arranged in two vertical rows parallel to each other, one above the top horizontal coil 121 and the other below the top horizontal coil 121 on the same vertical symmetry axis as the top horizontal coil 121 . be done.
　図２１は、金属帯体１４０の上下振動を許容しながらそのエッジ１４１の位置を正確に検出するアルゴリズムを表す図である。図中の「検体」は、金属帯体１４０を示す。図２１の左下部では、現実のエッジ１４１とコイル空間構成し、受信コイルアレイ１１０が上下２個あり、それぞれコイルＡ、Ｂ、Ｃ、ＤおよびＥが、等間隔で並んでいる。エッジ１４１の位置が、Ａ位置の場合とＢ位置の場合が図示されている。図２１の左上部のグラフは、一方の受信コイルアレイ１１０において、縦軸を各コイルの振幅出力、横軸を金属帯体１４０のエッジ１４１の位置にて、金属帯体１４０が遠距離の場合、中距離の場合、近距離の場合の各コイルそれぞれの振幅出力曲線を表している。金属帯体１４０が、どのコイル出力も共通して、近距離では傾斜が大きい出力曲線、中距離では傾斜が中ぐらいの出力曲線、遠距離では傾斜が小さい出力曲線となっている。エッジ１４１の位置がＡ位置の場合かつ金属帯体１４０が近距離の場合、コイルＡの出力が最も高く、次にコイルＢの出力、次にコイルＣ出力、次にコイルＤ出力と並び、一番低いコイルＥ出力が得られる。エッジ位置がＡ位置の場合で、金属帯体１４０が中距離の場合、金属帯体１４０が遠距離の場合、各コイルの電圧は低くなるが、同様に、各コイル出力は、同一順番に並ぶ。エッジ位置Ｂにおいても、同様なコイル電圧の順番が得られる。ただし、コイル内から外れ、直線性が得られないコイル出力Ａとコイル出力Ｂは、演算から除く。図２１右上部のグラフは、縦軸を各コイルの振幅出力、横軸を各コイルの順番の位置とした演算空間上でのコイル位置とコイル振幅出力電圧特性を表している。コイルの位置と間隔は、メートル単位を使用し、実際のコイル配列順番に従ってメートル単位で間隔を開けた位置で各コイルの出力電圧をプロットする。プロットは、左上部のグラフで得られた各コイル出力電圧を、右上部のグラフへ射影する。エッジ位置がＡ位置の場合かつ金属帯体１４０が近距離の場合、計測外とするコイル出力ＡとＥを除き、コイルＢ，Ｃ，Ｄの出力は、直線で結ばれる。エッジ位置がＡ位置で、金属帯体１４０が中距離の場合、金属帯体１４０が遠距離の場合、も同様にコイルＢ，Ｃ，Ｄの出力によって直線が結ばれる。受信コイルアレイ１１０は、同じ垂直位置に上下距離を違えて２枚あるので、それぞれの受信コイルアレイ１１０で得られた直線間の交点が得られる。この交点は、演算空間上の仮想エッジ位置としてよい。エッジ位置がＢ位置でも同様に直線が得られ、交点が得られる。演算空間上の仮想エッジ位置ＡとＢの差（メートルのデータ）は、実際の空間上のエッジ位置の距離差（メートル単位）に等しい。 FIG. 21 is a diagram showing an algorithm for accurately detecting the position of the edge 141 while allowing vertical vibration of the metal strip 140. FIG. A “specimen” in the drawing indicates the metal strip 140 . In the lower left part of FIG. 21, a real edge 141 and a coil space are formed, and there are two upper and lower receiving coil arrays 110, and coils A, B, C, D and E are arranged at regular intervals. A case where the position of the edge 141 is at the A position and a case where it is at the B position are illustrated. In the upper left graph of FIG. 21, in one receiving coil array 110, the vertical axis is the amplitude output of each coil, the horizontal axis is the position of the edge 141 of the metal strip 140, and the metal strip 140 is at a long distance. , the amplitude output curve of each coil for medium range and short range. The metal strip 140 has an output curve with a steep slope at a short distance, an output curve with a moderate slope at a medium distance, and an output curve with a small slope at a long distance, which are common to all coil outputs. When the position of the edge 141 is the A position and when the metal strip 140 is at a short distance, the output of the coil A is the highest, followed by the output of the coil B, then the output of the coil C, then the output of the coil D, and so on. The lowest coil E output is obtained. When the edge position is the A position, the voltage of each coil is low when the metal strip 140 is at a medium distance, and when the metal strip 140 is at a long distance, but similarly, the coil outputs are arranged in the same order. . At edge position B, a similar order of coil voltages is obtained. However, coil output A and coil output B, which are out of the coil and cannot obtain linearity, are excluded from the calculation. The graph in the upper right part of FIG. 21 represents the coil position and the coil amplitude output voltage characteristic in a calculation space where the vertical axis is the amplitude output of each coil and the horizontal axis is the position of each coil in order. Coil positions and spacings are in units of meters, and the output voltage of each coil is plotted at locations spaced in meters according to the actual coil array order. The plot projects each coil output voltage obtained in the upper left graph onto the upper right graph. When the edge position is position A and the metal strip 140 is at a short distance, the outputs of the coils B, C, and D are connected by a straight line, except for the coil outputs A and E, which are not measured. When the edge position is position A and the metal strip 140 is at a medium distance, and when the metal strip 140 is at a long distance, the outputs of the coils B, C, and D similarly connect straight lines. Since there are two receiving coil arrays 110 at the same vertical position with different vertical distances, the points of intersection between the straight lines obtained from the respective receiving coil arrays 110 can be obtained. This intersection point may be a virtual edge position on the calculation space. Even if the edge position is the B position, a straight line is obtained in the same way, and an intersection point is obtained. The difference between the virtual edge positions A and B in the calculation space (data in meters) is equal to the distance difference (in meters) between the edge positions in the actual space.
　本発明のアルゴリズムが成立するには、三つの条件が満たされていなければならない。第一条件は、受信コイルアレイ１１０の各コイルの検出特性が同一でなければならない。第二条件は、各受信コイルのエッジ位置－出力特性が直線形でなければならない。第三条件は、各受信コイルのエッジ位置－出力特性の距離別出力特性線が交わる交点の精度が高いこと。すなわち、広い距離範囲にわたって交点ができるだけ一点に収束していることが必要である。 For the algorithm of the present invention to work, three conditions must be met. The first condition is that the detection characteristics of each coil of the receiving coil array 110 must be the same. The second condition is that the edge position-output characteristic of each receiving coil must be linear. The third condition is that the accuracy of the intersection point where the distance-dependent output characteristic lines of the edge position-output characteristics of each receiving coil intersect is high. That is, it is necessary that the points of intersection converge to one point as much as possible over a wide range of distances.
　第一条件は、前述の発明の効果の項にて実験証明している。 The first condition is experimentally proven in the section on the effect of the invention mentioned above.
　第二の条件である直線性が得られる理由は、金属帯体１４０に流れる渦電流の流れ方と渦電流から発せられる二次磁界の受信コイル鎖交のメカニズムを解析する事で得られる。図２２は、励磁コイル中心部付近に受信コイル１１１を置き、金属帯体１４０に流れる渦電流の流れ方と電流密度分布を表す図である。励磁周波数を、励磁磁界が金属帯体１４０を弱透過できるほどに十分低く設定し、金属帯体１４０の励磁側の反対面を小さな受信コイル１１１で鉛直方向、水平方向にスキャンすることにより、透過した励磁一次磁界なのか、金属帯体１４０で流れる渦電流で生成された二次磁界なのか、二次磁界の強い箇所、極性反転する箇所を突き止めることによって得られた。図２３は、図２２のコイル構成のまま、この金属帯体１４０を横方向に受信コイル１１１と重なるように移動させたときに得られた実際の受信コイル１１１の振幅出力曲線を表すグラフである。グラフの受信コイル１１１の幅の間において、実際に直線性が得られていることがわかる。 The reason why the linearity, which is the second condition, is obtained is obtained by analyzing the flow of the eddy current flowing in the metal strip 140 and the mechanism of the interlinking of the secondary magnetic field generated by the eddy current with the receiving coil. FIG. 22 is a diagram showing how eddy currents flow in the metal strip 140 and the current density distribution when the receiving coil 111 is placed near the center of the exciting coil. The excitation frequency is set sufficiently low so that the excitation magnetic field can weakly penetrate the metal strip 140, and the surface opposite to the excitation side of the metal strip 140 is scanned vertically and horizontally with a small receiving coil 111. It was obtained by ascertaining the strong magnetic field and the polarity reversal, whether it is the primary magnetic field generated by the excited primary magnetic field or the secondary magnetic field generated by the eddy current flowing in the metal strip 140 . FIG. 23 is a graph showing an actual amplitude output curve of the receiving coil 111 obtained when the metal strip 140 is moved laterally so as to overlap with the receiving coil 111 with the coil configuration shown in FIG. . It can be seen that linearity is actually obtained between the widths of the receiving coil 111 in the graph.
　図２２によると、等磁束密度励磁コイル構成体１２０の励磁によって、励磁コイルのコイル線の頭上に強い渦電流密度が生じる。横方向の二つの平行渦電流線路がこれにあたる。そして、励磁コイルのコイル線の頭上ではないが、この横方向の二平行渦電流線路を結ぶエッジ１４１の位置に強い縦方向の渦電流密度が生じる。縦方向のエッジ渦電流線路がエッジ１４１に流れる。エッジ１４１から離れた金属帯体１４０の内側には、励磁コイルの頭上にもう一方の縦方向渦電流が流れるが、受信コイル１１１から十分離れるので（励磁コイル横幅が十分長いとし）、無視できる。図２４は、横方向の二平行渦電流線路のみが、金属帯体１４０のエッジ１４１が移動するに合わせて移動すると考え、二平行渦電流線路が発生する磁界の受信コイル鎖交の鉛直方向成分鎖交総磁束量を演算しグラフ化したものである。鉛直方向成分鎖交総磁束量は受信コイル１１１の振幅出力となる。ＬＤ３０ｍｍは、金属帯体１４０までの距離が３０ｍｍ、ＬＤ４５ｍｍは、４５ｍｍ、ＬＤ６０ｍｍは、６０ｍｍ、ＬＤ７５ｍｍは、７５ｍｍである。グラフは、受信コイル１１１へ重なり始めと重なり終わりで、曲線をとるが、受信コイル１１１に重なる領域では、直線変化となる。金属帯体１４０のエッジ１４１が受信コイル１１１に近づくとともに横方向の二平行渦電流線路も共に近づくので、直線変化となる。図２５は、縦方向のエッジ渦電流線路のみが、金属帯体１４０のエッジ１４１が移動するに合わせて移動すると考え、エッジ渦電流線路が発生する磁界の受信コイル１１１の鎖交の鉛直方向成分鎖交総磁束量を演算しグラフ化したものである。重なり始めと重なり終わりで、極性が異なるピークをとる。図２５では、グラフは両ピークの若干内側から直線域となっている。金属帯体１４０が近過ぎず、受信コイル１１１の横幅が広過ぎないときには、直線をとる。一方、金属帯体１４０までの距離が近過ぎたり、受信コイル１１１の横幅が広過ぎたりすると、受信コイル１１１の出力曲線は、Ｓ字曲線をとる。受信コイル１１１は金属帯体１４０から一定距離離れており、鎖交磁束の受信コイル１１１への入射角変化と鎖交磁束量変化によって直線変化となる。 According to FIG. 22, the excitation of the constant magnetic flux density excitation coil structure 120 produces a strong eddy current density above the coil wire of the excitation coil. Two laterally parallel eddy current lines correspond to this. A strong longitudinal eddy current density is generated at the position of the edge 141 connecting the two parallel eddy current lines in the lateral direction, although not above the coil wire of the exciting coil. A longitudinal edge eddy current line runs to edge 141 . On the inside of the metal strip 140 away from the edge 141, another longitudinal eddy current flows above the exciting coil, but it is far enough away from the receiving coil 111 (assuming the exciting coil lateral width is sufficiently long) and can be ignored. FIG. 24 shows the vertical component of the receiving coil linkage of the magnetic field generated by the two parallel eddy current lines, considering that only the two parallel eddy current lines in the horizontal direction move as the edge 141 of the metal strip 140 moves. The total amount of interlinkage magnetic flux is calculated and graphed. The total amount of vertical component interlinkage magnetic flux is the amplitude output of the receiving coil 111 . LD30mm is 30mm, LD45mm is 45mm, LD60mm is 60mm, and LD75mm is 75mm. The graph shows curved lines at the beginning and end of overlapping with the receiving coil 111, but changes linearly in the area overlapping with the receiving coil 111. FIG. As the edge 141 of the metal strip 140 approaches the receiving coil 111, the two lateral parallel eddy current lines also approach together, resulting in a linear change. FIG. 25 shows the vertical component of the interlinkage of the receiving coil 111 of the magnetic field generated by the edge eddy current line, considering that only the edge eddy current line in the vertical direction moves as the edge 141 of the metal strip 140 moves. The total amount of interlinkage magnetic flux is calculated and graphed. Peaks with different polarities are obtained at the beginning and end of the overlap. In FIG. 25, the graph becomes a linear region slightly inside both peaks. When the metal strip 140 is not too close and the width of the receiving coil 111 is not too wide, a straight line is taken. On the other hand, if the distance to the metal strip 140 is too short or the width of the receiving coil 111 is too wide, the output curve of the receiving coil 111 becomes an S-shaped curve. The receiving coil 111 is separated from the metal strip 140 by a certain distance, and linear changes occur due to changes in the incident angle of the interlinking magnetic flux to the receiving coil 111 and changes in the amount of interlinking magnetic flux.
　図２６は、図２４と図２５を足し合わせたグラフであり、横方向の二平行渦電流線路と縦方向のエッジ渦電流線路の三つの渦電流線路による受信コイル１１１の振幅出力電圧を表す。金属帯体１４０のエッジ１４１を移動させて得られた実際のグラフ図１４、１５および１６とほぼ同じ出力線形が得られている。受信コイル１１１内では、直線変化が得られている。 FIG. 26 is a graph obtained by adding together FIGS. 24 and 25, and represents the amplitude output voltage of the receiving coil 111 by three eddy current lines, ie, two parallel eddy current lines in the horizontal direction and edge eddy current lines in the vertical direction. Approximately the same output line shape as the actual graphs 14, 15 and 16 obtained by moving the edge 141 of the metal strip 140 is obtained. A linear change is obtained in the receiving coil 111 .
　図２１では、３つの受信コイル１１１によって直線出力結合が得られた。しかし、３つの受信コイル１１１だけで直線性を認識し抽出するのは難しい。そこで、図２７に示すような、受信コイル１１１の幅をある程度広くし、コイルの重なりピッチを狭くした受信コイルアレイ１１０が用いられる。各受信コイル１１１の外形縦幅は３０ｍｍ、横幅は１２８ｍｍとし、ピッチは１６ｍｍとし、基板８層を使って受信コイル１１１が重ね合わせられる。１６個の受信コイル１１１が同時処理され、出力曲線の中間部直線域、オーバーシュート域、アンダーシュート域の３つの領域を把握する。中間部の直線域を取り出すには、隣り合うコイル間の差分演算を行い、等しいコイル差分が得られる領域を中間部の直線域とする。１６個の受信コイル１１１の配列の横幅は、センターセンター間で２４０ｍｍ、端から端まで３６８ｍｍとなる。 In FIG. 21, three receiving coils 111 provided linear output coupling. However, it is difficult to recognize and extract linearity with only three receiving coils 111 . Therefore, as shown in FIG. 27, a receiving coil array 110 is used in which the width of the receiving coils 111 is widened to some extent and the overlapping pitch of the coils is narrowed. Each receiving coil 111 has a vertical width of 30 mm, a horizontal width of 128 mm, and a pitch of 16 mm. The receiving coils 111 are stacked using eight substrate layers. The 16 receive coils 111 are processed simultaneously to capture three regions of the output curve: the middle straight region, the overshoot region, and the undershoot region. In order to extract the intermediate linear area, a difference calculation between adjacent coils is performed, and the area where the equal coil difference is obtained is taken as the intermediate linear area. The width of the arrangement of the 16 receiving coils 111 is 240 mm between centers and 368 mm from end to end.
　エッジ１４１の位置が大きくずれる場合や、金属帯体１４０の規格幅が変わる場合があり、一例として、受信コイルアレイ１１０は、９６個の受信コイル１１１からなり、そのうちの１６個／アレイ（上下アレイの同じ水平位置のコイル群）が選択され同時処理される構成をとる。各受信コイル１１１はそれぞれ並び順に合わせてコイルアドレスを持ち、連続する１６個の受信コイル１１１のアレイもそれぞれ並び順に合わせてアレイアドレスを持つ。処理されるアレイアドレスは、現在のエッジ１４１の位置の真下にあり、エッジ１４１の移動に合わせて、アレイアドレスも移動する。メカニカルな移動ではなく、電気スイッチングによるコイル選択なので、高速で応答することができる。 There are cases where the position of the edge 141 deviates greatly and the standard width of the metal strip 140 may change. coil group at the same horizontal position) are selected and processed simultaneously. Each receiving coil 111 has a coil address according to the order of arrangement, and an array of 16 consecutive receiving coils 111 also has an array address according to the order of arrangement. The array address being processed is directly below the current edge 141 position, and as the edge 141 moves, the array address also moves. Since coil selection is based on electrical switching rather than mechanical movement, high-speed response is possible.
　第三条件の交点精度は、広い距離範囲にわたって距離無感交点の交点が、できるだけ一点に収束していることが求められる。広い距離変動範囲ながら高いエッジ１４１の位置検出精度を得るには、この第三条件の交点精度が高い方がよい。図２８および図２９は、等磁束密度励磁コイル構成体１２０を同じとしながら、各受信コイル１１１の縦横比を異にしていることを示すコイル配置図である。図２８では、各受信コイル１１１の縦幅は、横幅よりも広く、励磁コイル縦幅よりも広いものとし、受信コイル１１１の形状を横短縦長としている。図２９では、各受信コイル１１１の縦幅は、横幅よりも狭く、励磁コイル縦幅よりも狭いものとし、受信コイル形状を横長縦短としている。図３０は、受信コイル１１１の形状が、横短縦長の場合に得られた振幅出力曲線を表す。図３１は、受信コイル１１１の形状が、横長縦短の場合に得られた振幅出力曲線を表す。いずれの図も、縦軸を受信コイル１１１の振幅出力、横軸を金属帯体１４０のエッジ１４１の位置とし、横軸単位０．５を１５ｍｍとしている。Ｄ３０ｍｍは、金属帯体１４０までの距離が３０ｍｍ、Ｄ４５ｍｍは、同じく４５ｍｍ、Ｄ６０ｍｍは、同じく６０ｍｍ、Ｄ７５ｍｍは、同じく７５ｍｍである。図２８のように、受信コイル形状が横短縦長では、交点位置がバラついている。図２９のように、受信コイル形状が横長縦短では、交点位置が、おおよそ１点に収束している。 The intersection accuracy of the third condition requires that the intersection points of distance-insensitive intersection points converge to one point as much as possible over a wide range of distances. In order to obtain high position detection accuracy of the edge 141 over a wide distance variation range, it is preferable that the accuracy of the intersection of the third condition is high. 28 and 29 are coil arrangement diagrams showing that the aspect ratios of the receiving coils 111 are different while the uniform magnetic flux density excitation coil structure 120 is the same. In FIG. 28, the vertical width of each receiving coil 111 is wider than the horizontal width and wider than the vertical width of the excitation coil, and the shape of the receiving coil 111 is made horizontal and vertical long. In FIG. 29, the vertical width of each receiving coil 111 is narrower than the horizontal width and narrower than the vertical width of the excitation coil, and the receiving coil shape is horizontal and vertical. FIG. 30 shows an amplitude output curve obtained when the shape of the receiving coil 111 is horizontally short and vertically long. FIG. 31 shows an amplitude output curve obtained when the shape of the receiving coil 111 is horizontally long and vertically short. In both figures, the vertical axis represents the amplitude output of the receiving coil 111, the horizontal axis represents the position of the edge 141 of the metal strip 140, and the unit of 0.5 on the horizontal axis is 15 mm. D30mm is 30mm, D45mm is 45mm, D60mm is 60mm, and D75mm is 75mm. As shown in FIG. 28, when the shape of the receiving coil is horizontally short and vertically long, the positions of intersections are scattered. As shown in FIG. 29, when the receiving coil shape is horizontally long and vertically short, the intersection positions converge to approximately one point.
　さらに交点精度を上げるには、すなわち、より広い距離変動範囲で交点が１点に収束しているには、最適な受信コイル縦横比があることが分かる。図３２は、励磁コイル縦幅９０ｍｍとし、受信コイル１１１の縦幅３０ｍｍｘ横幅３０ｍｍとした場合の交点位置辺りの各距離の交点を表している。図３３は、励磁コイル縦幅９０ｍｍとし、受信コイル１１１の縦幅３０ｍｍｘ横幅１２０ｍｍとした場合の交点位置辺りの各距離の交点を表している。図３４は、励磁コイル縦幅９０ｍｍとし、受信コイル１１１の縦幅３０ｍｍｘ横幅１５０ｍｍとした場合の交点位置辺りの各距離の交点を表している。いずれの図も縦軸を受信コイル１１１の振幅出力、横軸を金属帯体１４０のエッジ１４１の位置とし、横軸単位は０．０５＝１．５ｍｍとしている。Ｄ３０ｍｍは、金属帯体１４０までの距離が３０ｍｍ、Ｄ４５ｍｍは、同じく４５ｍｍ、Ｄ６０ｍｍは、同じく６０ｍｍ、Ｄ７５ｍｍは、同じく７５ｍｍである。 It can be seen that there is an optimum receiving coil aspect ratio for further increasing the intersection accuracy, that is, for the intersection to converge to one point over a wider distance variation range. FIG. 32 shows intersection points of distances around the intersection position when the exciting coil has a vertical width of 90 mm and the receiving coil 111 has a vertical width of 30 mm and a horizontal width of 30 mm. FIG. 33 shows intersection points of distances around the intersection position when the exciting coil has a vertical width of 90 mm and the receiving coil 111 has a vertical width of 30 mm and a horizontal width of 120 mm. FIG. 34 shows the intersection points of distances around the intersection position when the exciting coil has a vertical width of 90 mm and the receiving coil 111 has a vertical width of 30 mm and a horizontal width of 150 mm. In both figures, the vertical axis is the amplitude output of the receiving coil 111, the horizontal axis is the position of the edge 141 of the metal strip 140, and the unit of the horizontal axis is 0.05=1.5 mm. D30mm is 30mm, D45mm is 45mm, D60mm is 60mm, and D75mm is 75mm.
　図３２では、Ｄ３０ｍｍとＤ４５ｍｍの交点が右端に、Ｄ４５ｍｍとＤ６０ｍｍの交点が中央に、Ｄ６０ｍｍとＤ７５ｍｍの交点が左端に並ぶ。図３３では、Ｄ３０ｍｍとＤ４５ｍｍの交点がほぼ中央に、Ｄ４５ｍｍとＤ６０ｍｍとＤ７５ｍｍの交点が左端で、ほぼ重なる。図３４では、Ｄ３０ｍｍとＤ４５ｍｍとＤ６０ｍｍの交点が左端で、ほぼ重なり、Ｄ６０ｍｍとＤ７５ｍｍの交点が右側に１．５ｍｍほどずれている。受信コイル１１１の縦幅３０ｍｍのまま横幅をさらに拡大すると、交点順番が図３２と逆順になり、交点間の距離の差が拡大していく。励磁コイル縦幅９０ｍｍ、受信コイル１１１の縦幅３０ｍｍとした場合、受信コイル１１１の横幅は１２０ｍｍあたりが、より広い距離範囲にわたり一点に交点が収束する。金属帯体１４０の近接を制限するメカニカル機構は簡単であるから、遠方側への離間で交点がずれるより、近方側への近接で交点のずれを認め、図３４の交点順序をとらないようにする。 In FIG. 32, the intersection point of D30 mm and D45 mm is on the right end, the intersection point of D45 mm and D60 mm is in the center, and the intersection point of D60 mm and D75 mm is on the left end. In FIG. 33, the intersection point of D30 mm and D45 mm is almost at the center, and the intersection point of D45 mm, D60 mm and D75 mm is at the left end, and they almost overlap. In FIG. 34, the intersection of D30 mm, D45 mm, and D60 mm is at the left end and almost overlaps, and the intersection of D60 mm and D75 mm is shifted to the right by about 1.5 mm. If the horizontal width of the receiving coil 111 is further increased while the vertical width is 30 mm, the order of the intersection points is reversed from that in FIG. 32, and the difference in the distance between the intersection points increases. When the excitation coil has a vertical width of 90 mm and the receiving coil 111 has a vertical width of 30 mm, the crossing point converges on one point over a wider distance range when the horizontal width of the receiving coil 111 is around 120 mm. Since the mechanical mechanism for restricting the approach of the metal strip 140 is simple, rather than the crossing point shifting due to separation to the far side, the shift of the crossing point is recognized when approaching the near side, and the order of crossing points shown in FIG. 34 is not used. to
　図３５は、励磁コイル縦幅９０ｍｍとし、受信コイル１１１の形状を最適縦横比である縦３０ｍｍｘ横１２０ｍｍとした受信コイル１１１の出力曲線のズームアウトしたグラフであり、横軸単位は１．０＝３０ｍｍとしている。中央部で直線が得られており、交点精度が高いことがわかる。 FIG. 35 is a zoomed-out graph of the output curve of the receiving coil 111 with the excitation coil having a vertical width of 90 mm and the shape of the receiving coil 111 having an optimal aspect ratio of 30 mm×120 mm. 30 mm. A straight line is obtained at the central portion, and it can be seen that the intersection accuracy is high.
　図１９および図２０に戻って、距離変動フリーエッジ位置検出器１００の構成を説明する。１個の上面水平コイル１２１、２個の側面垂直コイル１２２からなる等磁束密度励磁コイル構成体１２０および、２個の受信コイルアレイ１１０は、それぞれ基板に配線されたパターンである。各基板は、定寸のセラミックアルミナパイプ１０１に樹脂全ネジ１０２と樹脂ナット１０３によって固定される。上面水平コイル基板１２３は、Ｈ型押し出し材１０４の中央梁面に固定される。２個の側面垂直コイル基板１２４は、ＳＵＳ櫛形基台１０５に固定され、ＳＵＳ櫛形基台１０５は、Ｈ型押し出し材１０４の側面中間凸部に固定される。上下の受信コイルアレイ基板１１２は、上面水平コイル基板１２３上に固定される。励磁コイル基板には、両サイドに位置決め用貫通穴が穴開けされ、位置決めラインがシルク印刷される。樹脂位置決めブロックの先端三角が当該穴に入り、位置決めラインに一致するように位置決めし、固定する。受信コイルアレイ基板１１２は、３つの樹脂位置決めブロックにより外形３点で位置決めされる。 Returning to FIGS. 19 and 20, the configuration of the distance variation-free edge position detector 100 will be described. The equal magnetic flux density excitation coil structure 120 consisting of one upper surface horizontal coil 121 and two side surface vertical coils 122, and two receiving coil arrays 110 are patterns wired on the substrate, respectively. Each substrate is fixed to a fixed size ceramic alumina pipe 101 by a resin full screw 102 and a resin nut 103 . The upper horizontal coil substrate 123 is fixed to the center beam surface of the H-shaped extruded member 104 . The two side vertical coil substrates 124 are fixed to the SUS comb-shaped base 105 , and the SUS comb-shaped base 105 is fixed to the middle convex portion of the side surface of the H-shaped extruded member 104 . The upper and lower receiving coil array substrates 112 are fixed on the upper horizontal coil substrate 123 . Positioning through holes are drilled on both sides of the exciting coil substrate, and positioning lines are silk-printed. The triangular tip of the resin positioning block enters the hole and is positioned and fixed so as to match the positioning line. The receiving coil array substrate 112 is positioned at three points on the outer shape by three resin positioning blocks.
　Ｈ型押し出し材１０４は、導電率の低いアルミ合金製押し出し材とし、外形ケース、兼、位置決め用基台として利用する。上部翼の内面凸凹面は、磁性塗料によって厚塗りされる。渦電流による二次磁界が出射され、受信コイル１１１に鎖交する事を防ぐ。上面は、樹脂蓋１０６によって、塞がれる。Ｈ型底部凹みには、制御用基板１０７が固定され、板金の底面蓋１０８で塞がれる。Ｈ型中央梁面には、配線用の穴が開けられる。 The H-shaped extruded material 104 is an aluminum alloy extruded material with low conductivity, and is used as an external case and as a positioning base. The inner uneven surface of the upper wing is thickly coated with magnetic paint. It prevents the secondary magnetic field generated by the eddy current from interlinking with the receiving coil 111 . The upper surface is closed with a resin lid 106 . A control substrate 107 is fixed in the H-shaped bottom recess, and is closed with a bottom lid 108 made of sheet metal. A hole for wiring is opened in the H-shaped central beam surface.
　本発明により、広い範囲の距離変動を許容しながらエッジ１４１の位置を高精度に測定することができる。２枚の距離の異なる受信コイルアレイ１１０から得られる直線特性出力の交点をエッジ１４１の位置とみなすので、金属帯体１４０の材質（透磁率、導電率）、厚さを無視することができる、材質毎の補正演算は必要としない、常時処理する受信コイル１１１を、エッジ１４１の位置に合わせてスイッチ選択するので、メカニカルスライダーを必要としない、応答速度が速い、また、周波数、励磁電流、受信ゲインの変更も可能といった利点がある。 According to the present invention, the position of the edge 141 can be measured with high accuracy while allowing a wide range of distance variation. Since the intersection of the linear characteristic outputs obtained from the two receiving coil arrays 110 with different distances is regarded as the position of the edge 141, the material (magnetic permeability, conductivity) and thickness of the metal strip 140 can be ignored. Correction calculation for each material is not required. Since the receiver coil 111 that is always processed is selected according to the position of the edge 141, no mechanical slider is required. Response speed is fast. There is an advantage that the gain can be changed.
　図３６は、本発明のコイルセットを用いた第２の利用形態であり、幅広の金属異物検出器２００のコイルセットの配置図である。本発明のコイルセットを用いた第２の利用形態は、微小金属異物検出に関する。 FIG. 36 is a second usage form using the coil set of the present invention, and is a layout diagram of the coil set of the wide metal foreign object detector 200. FIG. A second form of utilization using the coil set of the present invention relates to the detection of minute metal foreign matter.
　幅広の金属異物検出器２００は、等磁束密度励磁コイル構成体２２０と受信コイルアレイ２１０のコイルセットが二つ、上下に対向して配列され、検体２４０はその間を通る。
実施例１と同様に、受信コイルアレイ２１０は複数の受信コイル２１１からなり、等磁束密度励磁コイル構成体２２０は、上面水平コイル２２１および２個の側面垂直コイル２２２からなる。図３７は、幅広の金属異物検出器２００の励磁磁界を表す図である。等磁束密度励磁コイル構成体２２０の極性は、上コイルセットと下コイルセットで逆相とし、その反対極性の磁界は、図３７のように表される。上コイルセットと下コイルセットの挟まれた中間域では、磁束の向きが垂直で高磁束密度の励磁磁界が形成される。 The wide metal foreign object detector 200 has two coil sets of an equal magnetic flux density excitation coil structure 220 and a receiving coil array 210 arranged vertically facing each other, and a specimen 240 passes between them.
As in the first embodiment, the receiving coil array 210 consists of a plurality of receiving coils 211 , and the equal magnetic flux density excitation coil structure 220 consists of a top horizontal coil 221 and two side vertical coils 222 . FIG. 37 is a diagram showing the excitation magnetic field of the wide metal foreign object detector 200. FIG. The polarities of the equal magnetic flux density excitation coil structure 220 are opposite in phase between the upper coil set and the lower coil set, and the magnetic fields of the opposite polarities are represented as shown in FIG. In the intermediate region between the upper coil set and the lower coil set, an exciting magnetic field with a high magnetic flux density is formed in which the direction of the magnetic flux is vertical.
　受信コイルアレイ２１０は、上下のコイルセットそれぞれに有り、上面水平コイル２２１とほぼ同一の平面で左右対称に据える。各受信コイル２１１の縦幅は、受信コイル横幅より広く、励磁コイル縦幅より広い。微小金属異物に流れる渦電流ループはその体積に合わせて小さく、渦電流から発する二次磁界も凝集している。遠方に届く二次磁界の磁束密度は、非常に低いが、空間全等方に広がる。この弱いが等方に広がる二次磁界を検出するには、縦幅が広い受信コイル２１１の方がより多くの磁束を拾う事が出来る。金属異物検出器２００は、遠距離にある微小金属に、高磁束密度な励磁磁界を印加し、薄く広がる微小金属からの二次磁界を広く検出する。しかし、各受信コイル２１１の縦幅は広くとも、横幅は小さいので、コイル面積を小さく維持できる。コイル面積が小さいので、周辺空間からのノイズに対しては低感度を保つ。 The receiving coil arrays 210 are provided in each of the upper and lower coil sets, and are installed symmetrically on substantially the same plane as the upper horizontal coils 221 . The vertical width of each receiving coil 211 is wider than the horizontal width of the receiving coil and wider than the vertical width of the excitation coil. The eddy current loop flowing through the minute metal foreign matter is small according to its volume, and the secondary magnetic field generated from the eddy current is also condensed. The magnetic flux density of the far-reaching secondary magnetic field is very low, but spreads out in all isotropic directions in space. In order to detect this weak but isotropically spreading secondary magnetic field, the receiving coil 211 having a wider vertical width can pick up more magnetic flux. The metal foreign object detector 200 applies an exciting magnetic field with a high magnetic flux density to minute metals at a long distance, and widely detects secondary magnetic fields from thinly spreading minute metals. However, even if each receiving coil 211 has a large vertical width, the horizontal width is small, so the coil area can be kept small. Since the coil area is small, it maintains low sensitivity to noise from the surrounding space.
　一次磁界のキャンセル（磁界バランス）におけるバランス受信信号は、メカニカル調整ではなく電気的な調整が可能で、受信コイルアレイ２１０の全検出受信コイルにわたり共用できる。 The balanced received signal in canceling the primary magnetic field (magnetic field balance) can be adjusted electrically rather than mechanically, and can be shared across all detection receiving coils of the receiving coil array 210 .
　受信コイルアレイ２１０の受信コイル数を増加してアレイ横幅を長くし、励磁コイル横幅を長くすれば、感度低下することなく幅広な検出領域が得られる。各受信コイルは小口径なので、インダクタンスも低く、周波数帯域を高くでき、高感度にできる。また、各受信コイルは小口径であることから、周辺空間のノイズ源に低感度。励磁コイル縦幅を広げると、長距離検出が得られる。 By increasing the number of receiving coils in the receiving coil array 210 to lengthen the horizontal width of the array and lengthening the horizontal width of the excitation coil, a wide detection area can be obtained without lowering sensitivity. Since each receiving coil has a small diameter, the inductance is low, the frequency band can be increased, and the sensitivity can be increased. In addition, since each receiving coil has a small diameter, it has low sensitivity to noise sources in the surrounding space. Long-distance detection can be obtained by increasing the vertical width of the exciting coil.
　金属蓋等が付帯している検体２４０の異物金属検出では、上の受信コイルアレイ２１０ａの各コイル信号をバランス信号として、下の受信コイルアレイ２１０ｂの各コイルの信号に混合させても良く、上の受信コイルアレイ２１０ａの各コイルの信号出力を使用する。励磁コイルはもちろんの事、各受信コイル２１１は、上下で位置が揃っていなければならない。下の受信コイル２１１で蓋金属と金属異物を検出し、上の受信コイル２１１で蓋金属を検出したときに、それぞれ相応する上下位置のコイル間で信号が混合され、蓋金属の信号成分が上下コイルセット毎にキャンセルされる。上下コイルセットからそれぞれ金属蓋までの距離が異なる場合でも、増幅率調整でバランスさせてもよい。 In the detection of a foreign metal in a specimen 240 with a metal lid or the like, each coil signal of the upper receiving coil array 210a may be used as a balance signal and mixed with the signal of each coil of the lower receiving coil array 210b. receive coil array 210a. The receiving coils 211 as well as the exciting coils must be vertically aligned. When the lower receiving coil 211 detects the lid metal and the metallic foreign matter, and the upper receiving coil 211 detects the lid metal, the signals are mixed between the corresponding upper and lower coils, and the signal components of the lid metal are mixed up and down. Canceled for each coil set. Even if the distances from the upper and lower coil sets to the respective metal lids are different, they may be balanced by adjusting the gain.
　図３８および図３９は、本発明のコイルセットを用いた第３の利用形態である、金属構造物検査装置３００のコイルセットの配置図である。本発明のコイルセットを用いた第３の利用形態は、金属構造体の渦電流探傷に関する。 38 and 39 are arrangement diagrams of the coil set of the metallic structure inspection apparatus 300, which is the third usage mode using the coil set of the present invention. A third application form using the coil set of the present invention relates to eddy current flaw detection of metal structures.
　金属構造物検査装置３００は、図３８のように、等磁束密度励磁コイル構成体３２０と受信コイルアレイ３１０は、金属構造体表面３４０と平行に、溶接ライン３４１に沿ってスキャンされる。実施例１と同様に、受信コイルアレイ３１０は複数の受信コイル３１１からなり、等磁束密度励磁コイル構成体３２０は、上面水平コイル３２１および２個の側面垂直コイル３２２からなる。金属構造体表面３４０には、励磁コイルの二平行渦電流線路と対称となる位置に、同じく二本の平行渦電流線路が形成される。二平行渦電流線路から二次磁界が生成され、受信コイルアレイ３１０の各受信コイル３１１で鎖交される。溶接ライン３４１は、表面が凸凹状に波打っているので、得られる１Ｄ受信アレイの信号も、同様、波打ち信号配列として得られる。溶接割れ３４２が有る場合、溶接割れによって、渦電流の流れが阻害される。渦電流が阻害された箇所では、二次磁界の発生が無いので、その箇所に相当する受信コイル３１１は、低い信号レベルとなる。溶接表面の凸凹３４３に対し、溶接割れ３４２は急峻なピーク谷を取るので、溶接割れ３４２を検出できる。 As shown in FIG. 38, the metal structure inspection apparatus 300 scans the uniform magnetic flux density excitation coil structure 320 and the receiving coil array 310 along the welding line 341 in parallel with the metal structure surface 340 . As in the first embodiment, the receiving coil array 310 consists of a plurality of receiving coils 311 , and the equal magnetic flux density excitation coil structure 320 consists of a top horizontal coil 321 and two side vertical coils 322 . Similarly, two parallel eddy current lines are formed on the metal structure surface 340 at positions symmetrical to the two parallel eddy current lines of the excitation coil. A secondary magnetic field is generated from the two parallel eddy current lines and interlinked at each receiving coil 311 of the receiving coil array 310 . Since the weld line 341 has an undulating surface, the resulting 1D receiving array signals are also obtained as an undulating signal array. If weld cracks 342 are present, the weld cracks impede the flow of eddy currents. Since no secondary magnetic field is generated at the location where the eddy current is obstructed, the receiving coil 311 corresponding to that location has a low signal level. Weld cracks 342 can be detected because weld cracks 342 have sharp peaks and valleys against unevenness 343 of the weld surface.
　図３９は、等磁束密度励磁コイル構成体３２０を、金属構造体表面３５０の曲率に沿って同じ曲率の近接面とした構造を示す。金属構造体表面３５０と同じ曲率なので、各受信コイルは、金属構造体表面３５０と等距離になり、得られる１Ｄ受信アレイの信号は、フラットな信号配列を得る。図３８と同様、溶接表面の凸凹３５１に対し、溶接割れ３５２は急峻なピーク谷を取るので、溶接割れを検出できる。なお、図３７の等磁束密度励磁コイル構成は、扇型の形状をとるが、金属構造体表面３５０が凹曲面である場合は、逆扇形の形状としても良い。 FIG. 39 shows a structure in which the equal magnetic flux density excitation coil structure 320 is formed along the curvature of the metal structure surface 350 and the adjacent surface having the same curvature. Because of the same curvature as the metal structure surface 350, each receive coil is equidistant from the metal structure surface 350 and the resulting 1D receive array signals have a flat signal array. Similar to FIG. 38, weld cracks 352 have sharp peaks and valleys with respect to unevenness 351 of the weld surface, so weld cracks can be detected. The equal magnetic flux density excitation coil configuration in FIG. 37 has a sector shape, but if the metal structure surface 350 is a concave curved surface, it may have an inverted sector shape.
　金属構造物検査装置３００のコイルセットは、１Ｄコイルアレイでありながら、広い範囲を、隙間なく、リアルタイムに、高感度に、かつ、均質に検査できる。さらに、周波数、感度が可変である。１Ｄ磁界画像から表面の凸凹３４３、３５１と傷とを分離でき、スキャンによる２Ｄ磁界画像から傷形状が認識できる。 Although the coil set of the metal structure inspection device 300 is a 1D coil array, it can inspect a wide range without gaps, in real time, with high sensitivity, and with uniformity. Furthermore, frequency and sensitivity are variable. Surface irregularities 343 and 351 and flaws can be separated from the 1D magnetic field image, and the shape of the flaw can be recognized from the scanned 2D magnetic field image.
１０：受信コイルアレイ
１１：受信コイル
１２：受信コイルアレイ基板
１３：テスト用受信コイル
２０：等磁束密度励磁コイル構成体
２１：上面水平コイル
２２：側面垂直コイル
２３：上面水平コイル基板
２４：側面垂直コイル基板
４０：金属帯体
４１：エッジ
１００：距離変動フリーエッジ位置検出器
１０１：セラミックアルミナパイプ
１０２：樹脂全ネジ
１０３：樹脂ナット
１０４：Ｈ型押し出し材
１０５：ＳＵＳ櫛形基台
１０６：樹脂蓋
１０７：制御用基板
１０８：底面蓋
１１０：受信コイルアレイ
１１１：受信コイル
１１２：受信コイルアレイ基板
１２０：等磁束密度励磁コイル構成体
１２１：上面水平コイル
１２２：側面垂直コイル
１２３：上面水平コイル基板
１２４：側面垂直コイル基板
１４０：金属帯体
１４１：エッジ
２００：金属異物検出器
２１０：受信コイルアレイ
２１１：受信コイル
２２０：等磁束密度励磁コイル構成体
２２１：上面水平コイル
２２２：側面垂直コイル
２４０：検体
３００：金属構造物検査装置
３１０：受信コイルアレイ
３１１：受信コイル
３２０：等磁束密度励磁コイル構成体
３４０：金属構造体表面
３４１：溶接ライン
３４２：溶接割れ
３４３：凸凹
３５０：金属構造体表面
３５１：凸凹
３５２：溶接割れ

  10: Receiving coil array 11: Receiving coil 12: Receiving coil array substrate 13: Receiving coil for test 20: Equal magnetic flux density excitation coil structure 21: Top horizontal coil 22: Side vertical coil 23: Top horizontal coil substrate 24: Side vertical Coil substrate 40: Metal strip 41: Edge 100: Distance change-free edge position detector 101: Ceramic alumina pipe 102: Resin full thread 103: Resin nut 104: H-shaped extruded material 105: SUS comb base 106: Resin lid 107 : Control board 108: Bottom cover 110: Receiving coil array 111: Receiving coil 112: Receiving coil array board 120: Equal magnetic flux density excitation coil structure 121: Top horizontal coil 122: Side vertical coil 123: Top horizontal coil board 124: Side Vertical Coil Board 140: Metal Strip 141: Edge 200: Metal Foreign Object Detector 210: Receiving Coil Array 211: Receiving Coil 220: Equal Flux Density Excitation Coil Structure 221: Top Horizontal Coil 222: Side Vertical Coil 240: Specimen 300 : Metal structure inspection device 310: Receiving coil array 311: Receiving coil 320: Equal magnetic flux density excitation coil structure 340: Metal structure surface 341: Welding line 342: Weld crack 343: Unevenness 350: Metal structure surface 351: Unevenness 352: Weld crack

Claims (6)

  1. 　上面水平コイルおよび前記上面水平コイルの両側下に配される２つの垂直側面コイルからなり、前記２つの垂直側面コイルの極性は反対極性で互いに向き合い、前記上面水平コイルの極性は前記２つの垂直側面コイルから上面に流れる磁束と同じ極性をと励磁コイル構成体と、
    　一つまたは複数の受信コイルと、を備え、
    　前記一つまたは複数の受信コイルを、前記励磁コイル構成体に近接して配置することを特徴とするコイルセット。     comprising a top horizontal coil and two vertical side coils arranged under both sides of said top horizontal coil, the polarities of said two vertical side coils being opposite to each other, and the polarities of said top horizontal coil being opposite said two vertical side coils. an exciting coil structure having the same polarity as the magnetic flux flowing from the coil to the upper surface;
    one or more receive coils;
    A coil set, wherein the one or more receiving coils are arranged in close proximity to the excitation coil arrangement.
  2. 　前記複数の受信コイルは、全て同じ形状にして、一列に配列される受信コイルアレイであり、
    　前記受信コイルアレイの縦対称軸と請求項１に記載の励磁コイル構成体の縦対称軸とが一致するように、前記受信コイルアレイを前記励磁コイル構成体に組み合わせて配置することを特徴とするコイルセット。     The plurality of receiving coils are all of the same shape and are a receiving coil array arranged in a row,
    The receiving coil array is arranged in combination with the exciting coil assembly so that the axis of longitudinal symmetry of the receiving coil array and the axis of longitudinal symmetry of the exciting coil assembly according to claim 1 are aligned. coil set.
  3. 　前記受信コイルアレイを複数とすることを特徴とする請求項２に記載のコイルセット。 The coil set according to claim 2, wherein a plurality of said receiving coil arrays are provided.
  4. 　前記受信コイルアレイを２枚とし、前記励磁コイル構成体の前記上面水平コイルの上側と下側にそれぞれ配置することを特徴とする請求項３に記載のコイルセット。 4. The coil set according to claim 3, wherein there are two receiving coil arrays, which are arranged above and below the top horizontal coil of the exciting coil structure.
  5. 　２個の前記コイルセットは、前記励磁コイル構成体の前記上面水平コイルが対向するように配置され、
    　対向する前記上面水平コイルの励磁磁界の極性を互いに反対極性とすることを特徴とする請求項２に記載のコイルセット。     The two coil sets are arranged so that the top horizontal coils of the excitation coil structure face each other,
    3. A coil set according to claim 2, wherein the polarities of the exciting magnetic fields of said upper horizontal coils facing each other are opposite to each other.
  6. 　前記コイルセットが、横方向に湾曲した形状をとることを特徴とする請求項２に記載のコイルセット。

          3. The coil set of claim 2, wherein the coil set assumes a laterally curved shape.
PCT/JP2021/016693 2021-04-26 2021-04-26 Coil set WO2022230032A1 (en)

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56117178A (en) * 1980-02-20 1981-09-14 Shimadzu Corp Metal detector
JPS5863510U (en) * 1981-10-26 1983-04-28 株式会社エスジ− Output error correction device for variable magnetic resistance type position detection device
JPH10318985A (en) * 1997-05-22 1998-12-04 Takenaka Komuten Co Ltd Non-destructive diagnosing method of fracture of structural member and building with diagnosing function
JP2003185758A (en) * 2001-09-26 2003-07-03 Hilti Ag Inductive sensor unit for detecting ferromagnetic substance or non-ferrous electric conductor, and method therefor
US20050024048A1 (en) * 2003-07-28 2005-02-03 Manring Edward B. Device and method for measuring transient magnetic performance
JP2016080596A (en) * 2014-10-20 2016-05-16 日立Ｇｅニュークリア・エナジー株式会社 Eddy current flaw detection probe
JP2018031768A (en) * 2016-06-22 2018-03-01 メトラー−トレド・セーフライン・リミテッド Metal detection device
WO2021009825A1 (en) * 2019-07-16 2021-01-21 株式会社ニレコ Sensor component, sensor, and edge detection device

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56117178A (en) * 1980-02-20 1981-09-14 Shimadzu Corp Metal detector
JPS5863510U (en) * 1981-10-26 1983-04-28 株式会社エスジ− Output error correction device for variable magnetic resistance type position detection device
JPH10318985A (en) * 1997-05-22 1998-12-04 Takenaka Komuten Co Ltd Non-destructive diagnosing method of fracture of structural member and building with diagnosing function
JP2003185758A (en) * 2001-09-26 2003-07-03 Hilti Ag Inductive sensor unit for detecting ferromagnetic substance or non-ferrous electric conductor, and method therefor
US20050024048A1 (en) * 2003-07-28 2005-02-03 Manring Edward B. Device and method for measuring transient magnetic performance
JP2016080596A (en) * 2014-10-20 2016-05-16 日立Ｇｅニュークリア・エナジー株式会社 Eddy current flaw detection probe
JP2018031768A (en) * 2016-06-22 2018-03-01 メトラー−トレド・セーフライン・リミテッド Metal detection device
WO2021009825A1 (en) * 2019-07-16 2021-01-21 株式会社ニレコ Sensor component, sensor, and edge detection device

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