WO2010079836A1 - Bobine de détection pour détecteur de métal, et détecteur de métal - Google Patents

Bobine de détection pour détecteur de métal, et détecteur de métal Download PDF

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Publication number
WO2010079836A1
WO2010079836A1 PCT/JP2010/050186 JP2010050186W WO2010079836A1 WO 2010079836 A1 WO2010079836 A1 WO 2010079836A1 JP 2010050186 W JP2010050186 W JP 2010050186W WO 2010079836 A1 WO2010079836 A1 WO 2010079836A1
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WIPO (PCT)
Prior art keywords
sensor
coil
metal detector
magnetic field
metal
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PCT/JP2010/050186
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English (en)
Japanese (ja)
Inventor
信一 近藤
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トック・エンジニアリング株式会社
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Priority to JP2010545799A priority Critical patent/JP5418945B2/ja
Publication of WO2010079836A1 publication Critical patent/WO2010079836A1/fr

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    • 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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/02—Food
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/15—Medicinal preparations ; Physical properties thereof, e.g. dissolubility

Definitions

  • the present invention relates to a sensor coil for a metal detector and a metal detector for detecting metal. More specifically, the present invention relates to a metal detector sensor coil and a metal detector for detecting a metal shape such as a needle or powder according to shape.
  • Patent Document 1 discloses a metal foreign object detection device that detects a metal foreign object mixed in an object to be detected. According to this device, not only metal foreign matter such as stainless steel mixed in the object to be detected is detected, but also in the object to be detected such as food, medicine, industrial material wrapped in conductive packaging material such as aluminum. The mixed metal foreign matter can also be detected.
  • This metal foreign object detection device generates a minute magnetic field by a detection unit having a single coil having a configuration in which a lead wire is wound around a core, and detects a magnetic field detected from the metal foreign object in response to the minute magnetic field as a detection voltage of the coil, or The detection current is detected and output as a detection signal.
  • This minute magnetic field has a very small voltage or current applied to the coil at a frequency of several hundred Hz to several tens of kHz. Further, this minute magnetic field uses a non-linear portion in which the magnetic flux density (B) representing the magnetization characteristic and the magnetic field (H) are very small values near zero in the magnetization (BH) characteristics of the core constituting the coil. It is a thing.
  • Patent Document 3 filed and filed by the applicant of the present invention discloses "a metal detector sensor and a metal detector”.
  • the metal detector sensor disclosed in Patent Document 3 is a metal detector sensor for detecting a metal object in an object to be detected, and generates a magnetic field by passing an electric current to generate an alternating magnetic field.
  • This metal detector disclosed in Patent Document 3 includes a transport unit having a transport path for transporting an object to be detected, and a coil of a conductive wire that is provided in the middle of the transport path and generates a magnetic field by passing an electric current.
  • a metal detector comprising a sensor coil wound around a metal core, the magnet is arranged in a range covered by a magnetic field generated by the sensor coil, generates a magnetic line of force due to a static magnetic field, and magnetizes the metal object.
  • the current is an alternating current for generating an alternating magnetic field, and the magnet is a magnet disposed in contact with the core.
  • antioxidants deoxygenating agents
  • the main component of this antioxidant is powder iron.
  • metal detectors react well to this. That is, the powdered iron of these antioxidants is detected as a metal foreign object by the metal detector. Since the antioxidant is not a metal foreign object, improvement of the metal detector is required so that only the metal foreign object can be discriminated.
  • An object of the present invention is to provide a sensor coil for a metal detector and a metal detector that can detect and detect the shape of a metal object.
  • Another object of the present invention is to provide an antioxidant that is attached to a medicine, cosmetics, food, etc. or enclosed together with the packaged item, a sensor coil for a metal detector that can detect and detect a metal needle, and Provide a metal detector.
  • a sensor coil for a metal detector is a sensor coil for a metal detector for detecting a metal object in an object to be detected.
  • the sensor coil for a metal detector is a sensor coil for a metal detector for detecting a metal object in an object to be detected.
  • 3 A sensor coil that is a coil in which two conductive wires are wound around a metal core at the same time, and a magnetic field generated by the sensor coil is disposed in the vicinity of the core, and generates magnetic lines of force due to a static magnetic field, A magnet for magnetizing a metal object, and one of the three conductors is connected to a power source, and the remaining two conductors are used to detect the metal object. It is characterized by being.
  • a metal detector according to a third aspect of the present invention is the sensor coil for a metal detector according to the first or second aspect, wherein the magnet is disposed in contact with the core.
  • a metal detector includes a transport unit having a transport path for transporting an object to be detected, and a conductive coil provided in the middle of the transport path for generating a magnetic field by passing a current.
  • the sensor coil is a coil in which two conductors are wound around the core at the same time, and is disposed in a range covered by the magnetic field generated by the sensor coil.
  • a magnetic field generated by a static magnetic field and magnetizing the metal object, the current is an alternating current for generating an alternating magnetic field, and the magnet is disposed in contact with the core. It is a permanent magnet.
  • the metal detector according to the fifth aspect of the present invention is provided with a conveying means having a conveying path for conveying an object to be detected, and a coil of a conductive wire provided in the middle of the conveying path for generating a magnetic field by flowing an electric current.
  • the sensor coil comprising a sensor coil wound around a core, the sensor coil is formed by simultaneously winding the three conductive wires around the core, and is disposed in a range covered by the magnetic field generated by the sensor coil.
  • a metal detector includes a detection unit for detecting the presence or absence of a magnetic substance in an object to be detected, and the presence or absence of the magnetic substance by signal processing a detection signal output from the detection unit And a detection means comprising a signal processing unit for outputting an output signal indicating the result of the determination, and the detection unit has a sensor coil having a configuration in which a lead wire is wound around a core, and a voltage is applied to the sensor coil.
  • a minute alternating magnetic field is generated by applying or supplying an alternating current, and when the detected object passes in the vicinity of the sensor coil, the magnetic field generated by the magnetic material disturbs the alternating magnetic field,
  • the sensor coil is a coil in which the two conductors are wound around the core at the same time.
  • the detection unit If the object to be detected passes near the sensor coil, the magnetic field generated by the magnetic material disturbs the alternating magnetic field, and the sensor The state of the coil is changed, the detection unit outputs the detection signal according to the change, and when the detection signal has three or more peaks in the waveform of the detection signal, the signal processing unit The signal processing unit outputs the output signal indicating that the magnetic body is an elongated magnetic body, and when the detection signal has two or less peaks in the waveform of the detection signal, the signal processing unit The output signal indicating that the body is a magnetic powder body is output.
  • a metal detector according to a seventh aspect of the present invention is the metal detector according to the sixth aspect, characterized by comprising magnetizing means disposed in the vicinity of the iron core and having a magnet for magnetizing the detected object.
  • a metal detector according to an eighth aspect of the present invention is the metal detector according to the sixth aspect, wherein the sensor means for specifying the speed of the detected object passing through the sensor coil, and the signal processing unit uses the speed. Then, the waveform of the detection signal is normalized.
  • a metal detector is the metal detector according to the sixth aspect, wherein the detection unit is composed of a bridge circuit, and the signal processing unit modulates the detection signal to generate a modulation signal, A low-pass filter for removing harmonics from the modulation core; an envelope detector for detecting an envelope of a signal omitted from the low-pass filter; and a digital signal for converting the signal output from the envelope detector to a digital signal Signal converting means, and the bridge circuit includes a first coil and a second coil constituting the sensor coil wound by the bifilar winding or the trifilar winding, and a first resistor and a second resistor, and the first coil The first resistor, the second coil, and the second resistor are connected in series, and the second resistor is connected in series to the first coil.
  • the bridge circuit is configured, and the voltage is applied to the first terminal between the first resistor and the second resistor and the second terminal between the first coil and the second coil.
  • the third terminal between the first resistor and the first coil and the fourth terminal between the second resistor and the second coil are output terminals of the bridge circuit. To do.
  • a metal detector according to a tenth aspect of the present invention is the metal detector according to any of the sixth to ninth aspects, wherein the sensor coil has a first sensor and two second sensors, and the first sensor and the second sensor are: Between the first sensor and the second sensor, the first sensor is disposed with a space through which the detection object passes, and the longitudinal center of the first sensor with respect to the conveyance direction of the detection object
  • the first center line that is an axis and the second center line that is the center axis in the longitudinal direction of the second sensor have an angle
  • the first surface including the first center line and the second center line are It is characterized by being arranged in parallel with the 2nd surface containing.
  • a metal detector according to an eleventh aspect of the present invention is the metal detector according to the tenth aspect, wherein the first center line and the second center line are arranged in parallel.
  • a metal detector according to a twelfth aspect of the present invention is the metal detector according to the tenth aspect, wherein a third sensor is disposed between the first sensor and the second sensor, and the third sensor is arranged in the transport direction.
  • the third center line which is the center line in the longitudinal direction of the third sensor, has an angle, and the third surface including the third center line is orthogonal to the first surface and the second surface. It is characterized by.
  • a metal detector according to a thirteenth aspect of the present invention is the metal detector according to the eleventh aspect, wherein a third sensor is disposed between the first sensor and the second sensor, and the third sensor is located in the transport direction.
  • the third center line which is the center line in the longitudinal direction of the third sensor, has an angle, and the third surface including the third center line is orthogonal to the first surface and the second surface. It is characterized by.
  • the above-mentioned metal detector increases the accuracy of the signal waveform of the sensor coil, the relaxation of the directivity of the sensor coil, the averaging of the dynamic range of the sensor coil, and the shape discrimination.
  • the following effects can be obtained.
  • the shape of a metal object for example, a needle-shaped metal object or a powder
  • an antioxidant that is attached to pharmaceutical products, cosmetics, foods, etc. or enclosed together with the packaged items, and a metal that is intentionally mixed It became possible to detect and detect the needle.
  • FIG. 1 shows an outline of a metal detector 1 according to a first embodiment of the present invention.
  • FIG. 2 is a conceptual diagram illustrating a configuration example of the third sensor 7 according to the first embodiment of this invention.
  • FIG. 3 is a block diagram illustrating a configuration example of the metal detector 1 according to the first embodiment of this invention.
  • FIG. 4 is a circuit diagram showing an example of a circuit of the metal detector 1 according to the first embodiment of the present invention.
  • FIG. 5 is a flowchart showing the operation of the control unit of the metal detector 1 according to the first embodiment of the present invention.
  • FIG. 6 is an inclined view showing an example of arrangement of sensors of the metal detector 1 according to the first embodiment of the present invention.
  • 7A and 7B are external views of sensor arrangement examples of the metal detector 1 in FIG. 6.
  • FIG. 6 is an inclined view showing an example of arrangement of sensors of the metal detector 1 according to the first embodiment of the present invention.
  • FIG. 7A is a front view of FIG. 6, FIG. 7B is a side view of FIG. ) Is a plan view of FIG. 8A and 8B are diagrams showing measurement waveforms of Example 1.
  • FIG. 8A is an amplified signal obtained by amplifying a signal detected by a needle
  • FIG. 8B is an amplified signal obtained by detecting an antioxidant.
  • FIG. 8C shows the amplified signal
  • FIG. 8C shows the modulation signal of the antioxidant.
  • FIG. 9 is a circuit diagram showing an example of a circuit of the metal detector 1 according to the second embodiment of the present invention.
  • the metal detector 1 is for detecting or detecting a magnetic substance in the object 2 to be detected.
  • the metal detector 1 includes a sensor unit 3, a control unit 4 (see FIG. 3), and the like.
  • a sensor for detecting a magnetic body in the detection object 2 is built. This sensor is the 1st sensor 5, the 2nd sensor 6, and the 3rd sensor 7 in this embodiment.
  • the detection signal output from the sensor unit 3 is sent to the control unit 4.
  • the first sensor 5, the second sensor 6, and the third sensor 7 have the same structure in this example (details will be described later).
  • the control unit 4 analyzes the detection signal received from the sensor unit 3 and determines whether or not there is a magnetic substance in the detected object 2.
  • the control unit 4 outputs a signal indicating the result of this determination. Further, the control unit 4 analyzes the detection signal received from the sensor unit 3 and determines whether or not there is an elongated metal object such as a needle in the detected object 2.
  • the metal detector 1 can determine the shape of the needle and the antioxidant therein even when the detected object 2 is packaged in aluminum packaging.
  • the antioxidant is illustrated by reference numeral 2a and the needle is illustrated by reference numeral 2b.
  • An optical sensor 8a and an optical sensor 8b are disposed in the vicinity of the sensor unit 3.
  • the optical sensor 8a has a timing when the detected object 2 enters the sensor unit 3, and the optical sensor 8b includes the detected object 2 as a sensor unit. The timing to go out from 3 is detected.
  • an optical sensor 8 a for detecting the detected object 2 entering the sensor unit 3 is disposed at the entrance of the detected object 2 of the sensor unit 3.
  • the detected object 2 is conveyed in a state of being grasped by a belt or a human hand when a foreign object is detected.
  • an optical sensor 8b for detecting the detected object 2 that exits from the sensor unit 3 is disposed at the outlet of the detected object 2 of the sensor unit 3.
  • the detection object 2 passes through the optical sensor 8a, the first sensor 5 and / or the second sensor 6, the third sensor 7, and the optical sensor 8b in this order.
  • the conveyance direction of the detection object 2 is indicated by an arrow 2 ′.
  • the magnetic substance in the object to be detected 2 is magnetized by the action of the static magnetic field of the magnet 11 to generate a magnetic pole, or the magnetization of the magnetic substance is enhanced. This change in magnetic pole affects an alternating magnetic field of a sensor coil, which will be described later, and this is detected by a detection circuit.
  • the applicant of the present invention has proposed a sensor for a metal detector and a metal detector that detect a magnetic substance by disposing a magnet near the iron core of a sensor coil as disclosed in Patent Document 3 described above.
  • This embodiment is an embodiment in which the metal detector sensor and the metal detector described in Patent Document 3 are improved. Therefore, the magnet 11 may be arranged at any position as long as the magnet 11 is arranged in a range covered by an alternating magnetic field generated when an alternating current is passed through the sensor coil. However, if there is no problem even if the sensor detection function of the sensor coil is slightly lowered, this arrangement may be arranged outside the range covered by the alternating magnetic field as in the case of the magnet booster described in Patent Document 1 described above. good.
  • the sensor coils of the first sensor 5, the second sensor 6, and the third sensor 7 are excited with a weak current and / or voltage of several hundred Hz to several tens kHz.
  • the sensor coils of the first sensor 5, the second sensor 6, and the third sensor 7 are excited with a weak sinusoidal current of about 1 kHz.
  • the optical sensor 8a detects the timing when the detected object 2 is conveyed, passes through the optical sensor 8a, and outputs a first timing signal.
  • the optical sensor 8b detects the timing when the detected object 2 is conveyed, passes through the optical sensor 8b, and outputs a second timing signal.
  • the first timing signal and the second timing signal are transmitted to the control unit 4.
  • the control unit 4 receives the first timing signal and the second timing signal received from the optical sensor 8a and the optical sensor 8b, and calculates the conveyance speed at which the detected object 2 passes through the sensor unit 3. Then, the control unit 4 normalizes the signal gain and the signal period with respect to the average conveyance time using the conveyance speed.
  • the detection waveform when the metal object in the object to be detected 2 is detected is different.
  • the detected waveform is normalized using the average conveyance speed. In the case of this example, 80 m / min close to the actually measured average value is used as the average conveyance speed.
  • the optical sensor 8a is used. In this case, since there is no difference in the detected waveform due to individual differences, normalization is possible in the range of 40 m / min to 50 m / min.
  • the control unit 4 analyzes the detection signal of each sensor coil when the detected object 2 passes through the first sensor 5, the second sensor 6, and the third sensor 7, and outputs this as a digital signal.
  • the digital signal processing unit 20 determines whether or not the digital signal is a signal indicating a magnetic material. Then, the digital signal processing unit 20 outputs an output signal indicating an alarm. This output signal is transmitted from the digital signal processing unit 20 to an alarm device 22 (see FIG. 3) provided in the metal detector 1 or another machine connected to the metal detector 1. Appropriate measures are taken.
  • a signal tower can be exemplified.
  • Examples of other devices include a production line management computer, a factory management control computer, and an administrator computer.
  • the control unit 4 is installed adjacent to or near the sensor unit 3 while being connected to the sensor unit 3.
  • the control unit 4 is not necessarily installed in the vicinity of the sensor unit 3, and can be installed in any place as long as it can receive and process a detection signal from the sensor unit 3.
  • each of the first sensor 5, the second sensor 6, and the third sensor 7 includes a sensor coil.
  • the first sensor 5 and the second sensor 6 are arranged so that the detected object 2 passes between them.
  • the first sensor 5 is disposed on the upper side of the sensor unit 3
  • the second sensor 6 is disposed on the lower side of the sensor unit 3.
  • the first sensor 5 is for detecting a magnetic body that passes through the upper region of the sensor unit 3.
  • the second sensor 6 is for detecting a magnetic body that passes through the lower region of the sensor unit 3.
  • the distance between the first sensor 5 and the second sensor 6 can be adjusted according to the shape, height, length, width, and the like of the object 2 to be detected.
  • the third sensor 7 is arranged vertically. That is, the third sensor 7 is disposed in a space between the first sensor 5 and the second sensor 6.
  • the third sensor 7 can perform highly efficient detection when the needle in the detection object 2 is arranged so as to pass through the vicinity of the center thereof.
  • the first sensor 5, the second sensor 6, and the third sensor 7 each operate independently. If even one of the three sensor coils of the first sensor 5, the second sensor 6, and the third sensor 7 generates a needle signal, the digital signal processing unit 20 issues an alarm signal.
  • the object to be detected 2 is arranged so that it can pass between the first sensor 5 and the second sensor 6.
  • the third sensor 7 is disposed between the first sensor 5 and the second sensor 6, and the detection object 2 is disposed so as to pass through the vicinity of the third sensor 7.
  • Each sensor coil constituting the first sensor 5, the second sensor 6, and the third sensor 7 is configured by bifilar winding a conducting wire around one E core.
  • a bifilar-wound coil is one in which two conductors are wound together around a core and terminals are output as two separate coils.
  • FIG. 4 shows bifilar-wound coils L1-1 and L1-2. Since the first sensor 5, the second sensor 6, and the third sensor 7 have substantially the same structure, only the 31st sensor 7 will be described below as an example. However, although it may be the same, the magnet 11 is preferably slightly different in shape and arrangement.
  • FIG. 2 illustrates the structure of the third sensor 7.
  • 2 (a) is a front view of the third sensor 7
  • FIG. 2 (b) is a plan view of the third sensor 7 in FIG. 2 (a)
  • FIG. 2 (c) is an AA view in FIG. 2 (a).
  • FIG. 2A the third sensor 7 has an elongated rod shape.
  • the 3rd sensor 7 is the structure which wound the coil 13 along the longitudinal direction along the groove part of the iron core 12 of the electrically conductive material which has the shape of this elongate rod shape, and a cross-sectional structure is E shape.
  • a magnet 11 is disposed in the vicinity of the iron core of the third sensor 7 (fixed to the side surface in this example).
  • the magnet 11 is for magnetizing the magnetic body in the object 2 to be detected.
  • the magnet 11 is installed in front of the first sensor 5, the second sensor 6, and the third sensor 7 in the conveying direction of the detection object 2.
  • the object to be detected 2 is disposed so as to pass through the vicinity of the magnet 11 and then pass through the vicinity of each sensor coil.
  • the magnet 11 is attached to the iron core side surface of the iron core 12.
  • the magnet 11 is a permanent magnet.
  • the magnet 11 is composed of a plurality of magnet elements, and the magnet elements are arranged on the surface of the iron core 12 with magnetic poles alternately directed.
  • the adjacent magnet element is arranged with the south pole facing the iron core 12.
  • an alternating current is passed through the sensor coil of the third sensor 7, an alternating magnetic field is generated.
  • the static magnetic field by the magnet 11 exists simultaneously. Therefore, two types of magnetic fields independent from each other exist in the vector space, and the characteristics of each magnetic field can be utilized. Since the magnet 11 is fixed to the iron core 12, it does not have a relative speed with the third sensor 7 and is not affected by vibration or the like.
  • the iron core 12 is configured by laminating silicon steel plates or amorphous plates. Alternatively, a ferrite core or a permanent magnet may be used. Since the magnet is directly attached to the E core, the magnetic body is magnetized in the vicinity of the coil. This not only increases the detection sensitivity, but also facilitates extraction of signal waveform features.
  • austenitic stainless steel SUS304, etc.
  • the portion with the is magnetized by the action of a static magnetic field to generate a magnetic pole.
  • This change in magnetic pole affects the alternating magnetic field of the third sensor 7 and is detected by the detection circuit.
  • this effect appears greatly in the vicinity of the third sensor 7, it is possible to reliably detect minute debris with the third sensor 7.
  • ferromagnetic materials such as iron, nickel, cobalt contaminants, alloys thereof, and martensitic stainless steel, and the detection sensitivity is significantly improved over the prior art.
  • the range in which the magnetic field of the permanent magnet affects the fine metal piece can be greatly expanded, and the sensor detection distance can be greatly extended.
  • the optical sensor 8 a installed in front of the first sensor 5 is necessary for specifying the timing when the detected object 2 passes through the first sensor 5.
  • the optical sensor 8 b is also installed on the rear side of the first sensor 5.
  • the optical sensor 8a includes an optical oscillator for oscillating a detection light wave and an optical receiver for receiving the light wave. When the detected object 2 crosses the light wave and the optical receiver can no longer receive the light wave, it outputs a detection signal.
  • the optical sensor 8b includes an optical oscillator and an optical receiver. Using the signals detected by these two optical sensors, the speed and timing at which the detection object 2 passes through the sensor storage unit can be calculated. Using this speed, the detection waveform of the detection object 2 is normalized. However, in the case of a transport means for transporting the detection object 2 at a constant speed, only one optical sensor for detecting the detection object 2 is sufficient. Further, in the case of a transport unit that transports the detection object 2 at a constant speed, in an extreme case, detection can be performed without performing waveform normalization.
  • the optical sensors 8a and 8b are used.
  • a known arbitrary shape and detection method can be used instead of the optical sensors 8a and 8b.
  • an ultrasonic sensor or the like can be used.
  • FIG. 3 illustrates a configuration example of the metal detector 1 according to the present embodiment.
  • the metal detector 1 includes a sensor unit 3, a control unit 4, a digital signal processing unit 20, and the like. Furthermore, it has a touch panel 21, an alarm device 22, and a level meter 23.
  • the sensor unit 3 includes the first sensor 5, the second sensor 6, the third sensor 7, and the optical sensor 8 including the optical sensor 8a and the optical sensor 8b.
  • the control unit 4 is a circuit that processes various signals detected by the sensor unit 3 and outputs digital signals.
  • the digital signal processing unit 20 performs signal processing on the digital signal received from the control unit 4 to determine whether or not the magnetic material has been detected, and outputs a determination signal.
  • the digital signal processing unit 20 can be configured by any of a programmable logic circuit, a microcomputer, an electronic computer, and the like.
  • the touch panel 21 is a user interface for inputting instructions to the digital signal processing unit 20.
  • the touch panel 21 is a touch-type display that includes a plurality of buttons and the like for operation by an operator and includes a panel that displays an operation status.
  • the alarm device 22 outputs an alarm signal according to the determination result signal output from the digital signal processing unit 20.
  • the alarm device 22 emits an alarm signal by flashing or sounding a buzzer when a shortage is detected.
  • the alarm device 22 has a signal tower 22a that emits a color signal.
  • the signal tower 22a normally shines in a specific color, such as green, and emits another color, such as red, when an alarm signal is issued.
  • the alarm device 22 has a signal tower 22b that emits an audio signal.
  • the signal tower 22b is quiet during normal times when it does not detect a magnetic substance as a foreign object, and emits an audio buzzer when an alarm signal is issued.
  • the level meter 23 is attached for checking the noise situation around the place where the metal detector 1 is installed and for displaying that the sensor is operating normally.
  • the level meter 23 generates a level signal by shaping the signal voltage and converting the level of the DC voltage. This level signal is displayed on the display means.
  • the display means is a display composed of LEDs or the like. Further, the level of the level meter 23 is displayed on the touch panel 21 (see FIG. 3). This level meter is not an essential component of the metal detector 1, but is convenient for grasping the environmental situation.
  • FIG. 4 shows an outline of a configuration example of the control unit 4 for processing a signal detected by the first sensor 5.
  • a similar circuit is prepared for the second sensor 6 and the third sensor 7.
  • the digital signal processing unit 20 is connected in parallel with three circuits for the first sensor 5, the second sensor 6 and the third sensor 7.
  • the control unit 4 illustrated in FIG. 4 includes a power supply circuit 41, a bridge circuit 42, an amplifier 43, a phase transfer circuit 44, a multiplier 45, a low-pass filter (LPF) 46, an envelope detection circuit 47, a DSP filter 48, a constant current.
  • the circuit 49 is configured.
  • the power circuit 41 supplies AC power to the control unit 4.
  • the power supply circuit 41 supplies power to the bridge circuit 42.
  • the power supply circuit 41 preferably supplies an alternating current to the bridge circuit 42 via an input matching transformer.
  • an input matching transformer not shown
  • the bridge circuit 42 is a circuit that detects a magnetic material.
  • the bridge circuit 42 includes two coils L1-1 and L1-2 that constitute the first sensor 5 described above.
  • the bridge circuit 42 includes two coils and two resistors R1 and R2, and is normally balanced.
  • the resistor R3 is a variable resistor for adjusting a resistor connected in series with the resistors R1 and R2.
  • the resistor R3 is a variable element and is divided.
  • the divided resistor R3 is connected in series with the resistors R1 and R2. Therefore, in practice, the bridge circuit 42 can be regarded as comprising the coil L1-1, the coil L1-2, and the resistors R1 and R2.
  • connection terminal between the coil L1-1 and the resistor R1 and the connection terminal between the coil L1-2 and the resistor R2 become two output terminals, which are connected to the amplifier 43.
  • the bridge circuit 42 since the bridge circuit 42 is normally balanced, there is no voltage difference and almost no current flows.
  • a minute current flows through the bridge circuit 42 and the resistor R4.
  • the minute current is preferably about several mA to several tens mA, for example.
  • the constant current circuit 49 is a circuit for allowing a constant current to always flow through the resistor R4. After the balance of the bridge of the bridge circuit 42 is lost, the constant current circuit 49 quickly returns to the balanced state.
  • the balance of the bridge circuit 42 is lost. Therefore, a voltage difference is generated at this output terminal, and the potential difference that has lost the balance of the bridge circuit 42 is amplified by a differential amplifier to be a signal. For example, upon detecting a Tetsuhari large diameter 0.8 mm, length 35 mm, the output terminal can potential difference of about ⁇ 10mV P-P. Thereby, the bridge circuit 42 outputs a detection signal. This detection signal is amplified by the amplifier circuit 43.
  • the amplifier 43 is a circuit that amplifies the output signal of the bridge circuit 42 and is a differential amplifier circuit.
  • the differential amplifier circuit uses an instrumentation amplifier (Instrumentation Amplifier).
  • the signal amplified by the amplifier circuit 43 is input to the multiplier 45.
  • the phase transfer circuit 44 is a circuit that converts the phase of the signal from the power supply circuit 41 and outputs a reference signal. That is, the reference signal from the power supply circuit 41 is shifted in phase by 90 ° to generate a reference signal. This reference signal is input to the multiplier 45.
  • the multiplier 45 multiplies the signal output from the amplifier 43 by the reference signal from the phase transfer circuit 44 to create a reference frequency and a high-frequency component twice the reference frequency.
  • the reference frequency here is a current and / or voltage frequency illustrating the sensor coil of the bridge circuit 42.
  • the multiplier 45 modulates the signal output from the amplifier 43.
  • a signal output from the multiplier 45 is referred to as a modulation signal.
  • the LPF 46 is a circuit that removes a signal having an unnecessary frequency from the modulation signal.
  • the envelope detection circuit 47 is a circuit that specifies and outputs only the foreign substance signal including the envelope from the signal output from the LPF 46.
  • the multiplier 45 modulates the phase signal of the reference frequency, and outputs a high frequency component that is twice the reference phase frequency.
  • the LPF 46 cuts high-frequency components and extracts a signal that depends only on a foreign substance signal (a signal depending on the magnetic material) related to the excitation signal.
  • the DSP filter 48 shapes the waveform of the signal output from the envelope detection circuit 47, converts it into a digital signal, and adjusts the reception sensitivity.
  • the signal that has passed through the DSP filter 47 is input to the digital signal processing unit 20 at the subsequent stage.
  • the digital signal processing unit 20 standardizes the waveform signal and specifies the needle signal.
  • the digital signal processing unit 20 is preferably composed of a memory circuit, an arithmetic circuit, an amplitude comparison / signal extraction circuit, and the like.
  • the digital signal processing unit 20 receives a signal from the optical sensor 8 and calculates the conveyance speed of the object 2 to be detected. Therefore, the digital signal processing unit 20 receives the digital signal from the DSP filter 48 and normalizes the detection waveform together with the speed signal of the detected object 2 and the like. Then, the detection waveform is determined.
  • the digital signal processing unit 20 outputs an output signal to the alarm device 22 when it is determined that a needle-like magnetic material has been detected.
  • the digital signal processing unit 20 receives a signal from the touch panel 21 and a signal from the optical sensor 8.
  • FIG. 5 is a flowchart showing an operation example of the digital signal processing unit 20.
  • the digital signal processing unit 20 receives a signal from the touch panel 21 and executes the command in accordance with an instruction from the touch panel 21 (step 10-14).
  • the touch panel 21 performs operations such as starting operation of the apparatus and inputting initial values, for example.
  • initial values the arrangement angle ⁇ of the first sensor 5, the second sensor 6, and the third sensor 7, and the distance between the optical sensor 8a and the optical sensor 8b are input and stored in the memory.
  • the apparatus is activated (step 16).
  • the digital signal processing unit 20 receives the entrance detection signal from the optical sensor 8a. At this time, the time t1 when the entrance detection signal is received is also acquired (step 18).
  • the digital signal processing unit 20 receives the exit detection signal from the optical sensor 8b. At this time, the time t2 when the exit detection signal is received is also acquired (step 20). The digital signal processing unit 20 receives from the DSP filter 48 a digital signal indicating an output signal of one or more of the first sensor 5, the second sensor 6, and the third sensor 7 (step 22). If there is no digital signal, the digital signal processing unit 20 waits for an entrance detection signal from the optical sensor 8a (step 22 ⁇ step 18).
  • the digital signal processing unit 20 calculates the conveyance speed V1 using the signal received from the optical sensor 8 (step 24). This calculation is performed in the following steps. First, a time difference t between time t2 and time t1 is obtained.
  • the digital signal processing unit 20 standardizes the waveform signal using the transport speed V1 (step 26). In this normalization, for example, the waveform signal is stretched or compressed so that the time width and amplitude value (gain) of the reference waveform are the same. The digital signal processing unit 20 performs normalization by extending or compressing the waveform signal so that the time width and the amplitude value (gain) of the reference waveform are the same using the conveyance speed V1.
  • the digital signal processing unit 20 extracts the features from the standardized waveform that has been standardized (step 28). As features, for example, the uneven portion of the waveform, the number of peaks, the maximum value and the average value of each peak are compared.
  • the waveform feature indicating the extracted feature is compared with the comparison feature 1 (see the description below) (step 30).
  • This feature 1 is a feature showing, for example, iron powder described later.
  • step 34 when both features match, it is determined that the digital waveform is that of feature 1, and is output (step 34). Then, the waveform feature indicating the extracted feature is compared with the feature 2 for comparison (see the description below) (step 36). This feature 2 is a feature showing a needle to be described later, for example. If both features match in this comparison, the digital waveform is judged to indicate feature 2 and output (steps 38 and 40). Then, the next detection is performed (step 42).
  • the detected object 2 has an elongated magnetic body.
  • This magnetic body is, for example, a needle or a metal fragment mixed in food, medicine or the like.
  • a waveform having three peaks as shown in FIG. 8A is obtained. This is clearly different from the above-described waveform of iron powder.
  • the peaks of the detected waveform can be counted by signal processing to determine the shape of the magnetic material. In particular, looking at the waveform of FIG. 8A, the third small peak is not in FIG. 8B.
  • the metal detector 1 of the present embodiment may be used, for example, in a supermarket fee payment system. It is installed adjacent to the cash register or built in the cash register, and performs the cash register operation and the needle inspection simultaneously. At this time, the operator may handle (carry) the product by hand and pass the sensor portion of the register and the discriminating device. Since there are individual differences in the transport time of the operator, as described above, the optical sensor 8a and the optical sensor 8b are attached to the entrance and the exit of the sensor of the discrimination device, respectively.
  • FIG. 7 is a front view (FIG. 7A), a side view (FIG. 7B), and a plan view (FIG. 7). (C)).
  • an arrow 2 ′ indicates the conveyance direction of the detected object.
  • a housing 3 ′ in which a sensor is stored is shown by an imaginary line.
  • the first sensor 5 and the second sensor 6 are arranged on parallel planes.
  • the first sensor 5 and the second sensor 6 are arranged with a space in which the detection object 2 is conveyed therebetween.
  • the 1st sensor 5 and the 2nd sensor 6 are arranged in the position where the central axis of the longitudinal direction becomes parallel.
  • the longitudinal central axes of the first sensor 5 and the second sensor 6 are arranged to have a predetermined angle with respect to the transport direction 2 ′. In the drawing, they are arranged at angles ⁇ 1 and ⁇ 2 counterclockwise with respect to the transport direction.
  • the third sensor 7 is arranged in the vertical direction at an angle with the first sensor 5 and the second sensor 6. Further, as shown in FIG. 7A, the third sensor 7 is arranged so as to form a predetermined angle, for example, a counterclockwise angle ⁇ 3 , with a surface perpendicular to the transport direction 2 ′. .
  • these angles ⁇ 1 , ⁇ 2 , and ⁇ 3 are preferably optimized depending on the type and shape of the object to be detected.
  • the first center line that is the center axis in the longitudinal direction of the first sensor 5 and the second center line that is the center axis in the longitudinal direction of the second sensor 6 with respect to the conveyance direction of the detection object 2. are arranged with an angle.
  • the first center line and the second center line are arranged in parallel. This is because when the signals are arranged in parallel to each other, the phases of the detection signals of the first sensor and the second sensor appear in synchronism even if there is a difference in strength. This is to make it easier.
  • the arrangement of the first sensor 5, the second sensor 6, and the third sensor 7 can be expressed strictly in mathematical terms, the first surface including the first center line of the first sensor 5, and the second sensor 6.
  • the second surface including the second center line is a parallel plane.
  • the first center line of the first sensor 5 may be arranged at any angle with respect to the conveyance direction of the detection object as long as it is within the first plane.
  • the second center line of the second sensor 6 is It may be arranged at any angle within the second plane with respect to the conveyance direction of the detected object.
  • the third surface including the third center line that is the central axis in the longitudinal direction of the third sensor 7 is orthogonal to the first surface and the second surface. As long as the 3rd center line of the 3rd sensor 7 is in a 3rd surface, you may arrange
  • FIG. 9 shows a second embodiment of the sensor coil of the present invention.
  • the second embodiment is basically the same as the above-described first embodiment, and only different parts will be described here.
  • the sensor coil of the second embodiment is a trifilar winding. Trifilar winding is a method of winding three conductors around an iron core simultaneously. Therefore, the sensor coil of the third embodiment has a structure in which three conducting wires are wound around an E-type iron core. Therefore, the sensor coil has three pairs of terminals.
  • one pair L1-0 is connected to an excitation power source 41 for constant current excitation.
  • the remaining pair becomes the coils L1-1 and L1-2 of the two arms constituting the bridge circuit.
  • the advantage of the trifilar winding is that the excitation power supply and the electronic circuit of the bridge circuit can be insulated and the bridge circuit can be configured. Therefore, there is an advantage that the input matching transformer used for the power source of the first embodiment is not necessary.
  • FIG. 8 is a photograph showing an experimental example using the metal detector 1 of the present invention.
  • FIG. 8 is an oscilloscope waveform in which a needle and an antioxidant are detected by a bridge circuit, and an amplified signal after amplification and a modulated signal after modulation with a reference signal are measured.
  • the circuit shown in FIG. 4 was used.
  • an iron needle having a length of 35 mm and a thickness of 0.8 mm was used.
  • FIG. 8A shows the amplified signal of the needle.
  • FIG. 8B is an amplified signal of the antioxidant.
  • FIG. 8C shows a needle modulation signal.
  • FIG. 8D shows a modulation signal of the antioxidant.
  • the waveform in the case of a needle, the waveform has three peaks. This is presumably because the tip of the needle is sharp and the volume of the magnetic material of the detected object is accompanied by a sudden change.
  • the waveform In the case of an antioxidant, the waveform has two peaks. This waveform has two peaks as follows. The antioxidant is an aggregate of iron powder, and a signal is created assuming that the tip has an area, and the volume of the magnetic substance of the detected object is considered to be accompanied by a gradual change. The peaks of these waveforms can be compared to determine whether they are antioxidants or needles.
  • the present invention is preferably used in the field of detecting and using a magnetic substance contained in an object to be detected according to its shape, particularly in the field of manufacturing pharmaceuticals, cosmetics, and foods.
  • the present invention detects a metallic foreign object of a magnetic substance mixed in an object to be detected that is wrapped with a conductive packaging material such as aluminum vapor deposition or aluminum foil.
  • the present invention can be used in the field of detecting magnetic metal foreign matter mixed in frozen foods, food materials such as grains, pharmaceuticals, industrial materials and the like.

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Abstract

La présente invention concerne une bobine de détection pour un détecteur de métal et un détecteur de métal qui sont utilisés pour déterminer et détecter la forme de l’objet métallique d’un corps magnétique. La bobine de détection est formée par l’enroulement d’un fil autour d’un noyau par enroulement bifilaire ou enroulement trifilaire, et un aimant est disposé près du noyau. La bobine de détection est excitée par une alimentation infime en courant alternatif. Lorsqu’un objet devant être détecté passe au voisinage de la bobine de détection, un champ magnétique généré par le corps magnétique perturbe le champ magnétique CA de la bobine de détection et un circuit en pont détecte la variation du champ magnétique CA. Une section traitement de signaux traite la forme d’onde d’un signal de détection et extrait les caractéristiques de ceux-ci dans le but de déterminer la forme du corps magnétique. Lorsque la forme d’onde du signal de détection comporte trois pics ou plus, on décide que le corps magnétique est de forme aciculaire. Lorsque la forme d’onde du signal de détection comporte deux pics ou moins, on décide que le corps magnétique est de la poudre de fer.
PCT/JP2010/050186 2009-01-09 2010-01-08 Bobine de détection pour détecteur de métal, et détecteur de métal WO2010079836A1 (fr)

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CN107942396A (zh) * 2017-12-08 2018-04-20 青岛众海汇智能源科技有限责任公司 金属探测定位系统及探测定位方法
CN112505266A (zh) * 2020-11-19 2021-03-16 邓文朝 一种用于散料粉末食品检测的喉式金属探测仪

Families Citing this family (1)

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Publication number Priority date Publication date Assignee Title
KR101786790B1 (ko) * 2015-09-07 2017-10-18 주식회사 센지켄 금속 탐지 센서 및 이를 포함하는 금속 탐지기

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JPH02287149A (ja) * 1989-04-27 1990-11-27 Matsushita Electric Ind Co Ltd 導体欠損検出装置
JP3875161B2 (ja) * 2002-08-28 2007-01-31 トック・エンジニアリング株式会社 金属探知機用センサーと金属探知機

Patent Citations (2)

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Publication number Priority date Publication date Assignee Title
JPH02287149A (ja) * 1989-04-27 1990-11-27 Matsushita Electric Ind Co Ltd 導体欠損検出装置
JP3875161B2 (ja) * 2002-08-28 2007-01-31 トック・エンジニアリング株式会社 金属探知機用センサーと金属探知機

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107942396A (zh) * 2017-12-08 2018-04-20 青岛众海汇智能源科技有限责任公司 金属探测定位系统及探测定位方法
CN112505266A (zh) * 2020-11-19 2021-03-16 邓文朝 一种用于散料粉末食品检测的喉式金属探测仪

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