Coil structure of a magnetic field probe, attitude recognition method and probe

Abstract

This invention discloses a coil structure, attitude recognition method, and detector for a through-type detector. The coil structure of the through-type detector includes two opposing sets of transmitting coils arranged on both sides, forming a central channel for the passage of the object being measured. Each side of the bilateral transmitting coil sets includes a first transmitting coil, a second transmitting coil, and a third transmitting coil. The first transmitting coil includes an upper coil and a lower coil, and is respectively positioned within the area enclosed by the second and third transmitting coils. This improves detection stability and avoids missed detections. The method separates the received signal using different frequencies to determine the attitude of a plate-shaped metal object. The detector possesses various functional modules for attitude recognition of plate-shaped metal objects, enabling attitude recognition of these objects.

Description

Technical Field

[0001] This invention relates to the field of walk-through detector technology, and more particularly to a coil structure, attitude recognition method, and detector for a walk-through detector. Background Technology

[0002] In traditional detection technologies, coils are installed inside the door panels on both sides of the walk-through detector. The magnetic field lines inside the detector are distributed horizontally from one side of the door panel to the other. When a person carrying a plate-shaped metal object, such as a mobile phone, tablet, or copper plate, passes through the walk-through detector while keeping the maximum cross-section of the plate-shaped metal object parallel to the direction of the horizontal magnetic field lines, the eddy current effect generated is small because the cross-section of the plate-shaped metal object passing through the horizontal magnetic field lines is very small, and fewer magnetic field lines pass through. As a result, the detected eddy current signal is weak, which may lead to the detector missing detections. The reliability of the detection results is greatly reduced. In other words, traditional walk-through detectors cannot guarantee that metal panels or mobile phones can be detected in any posture.

[0003] In addition, regulators in the field of detector applications hope to be able to detect the posture of plate-shaped metal objects in order to more easily find the location where the person being tested has hidden the plate-shaped metal object. Summary of the Invention

[0004] This invention provides a coil structure for a walk-through detector, a method for recognizing the posture of a plate-shaped metal object, and a detector, which improves the detection reliability of the walk-through detector, reduces missed detections, and identifies the posture of the object passing through the detection area.

[0005] In a first aspect, the present invention provides a coil structure for a through-type detector, comprising: a pair of transmitting coils arranged opposite each other on both sides, with an intermediate channel between them for the passage of the object to be measured;

[0006] Each side of the bilateral transmitting coil group includes a first transmitting coil, a second transmitting coil, and a third transmitting coil. The first transmitting coil includes an upper coil and a lower coil, and is respectively located within the area enclosed by the second and third transmitting coils. The normal directions of the upper and lower coils on each side are opposite at the same time, and the normal directions of the two upper coils in the bilateral transmitting coil group are opposite at the same time. The normal directions of the bilateral second transmitting coils are in the same direction, and the normal directions of the bilateral third transmitting coils are opposite. Within the three-dimensional space of the intermediate channel, electromagnetic fields are formed in three directions: x, y, and z. The x-direction is perpendicular to the door panel, the y-direction is through the intermediate channel, and the z-direction is perpendicular to the ground. The x, y, and z directions are mutually perpendicular.

[0007] In this scheme, an electromagnetic field in the x-axis direction is generated by the normal direction of the double-sided second transmitting coils arranged in the same direction; an electromagnetic field in the y-axis direction is generated by the normal direction of the double-sided third transmitting coils arranged in opposite directions. Because the normals of the upper and lower coils of the double-sided first transmitting coils are opposite, and the normals of the upper coils on both sides are opposite, the electromagnetic fields are relatively compressed, forcing the magnetic field of the upper coil on one side to enter the lower coil on the same side, forming a ring-shaped magnetic field, thus generating a magnetic field in the z-axis direction. Therefore, when the maximum cross-section of the plate-shaped metal object is in any of the x, y, and z directions, a large number of magnetic field lines can pass through, generating a strong eddy current signal, thereby improving the reliability of the coil structure in detecting plate-shaped metal objects and avoiding missed detections. The first transmitting coil is placed within the area enclosed by the second transmitting coils, compensating for the loss of the magnetic field in the x-axis direction caused by the magnetic field compression of the upper and lower coils of the first transmitting coil structure due to their opposite normals, further improving the detection sensitivity of the coil structure when detecting plate-shaped metal objects parallel to the door panel. The first transmitting coil is positioned within the area enclosed by the third transmitting coil, further enhancing the magnetic field strength in the y-axis direction of the middle portion of the intermediate channel corresponding to the adjacent positions of the upper and lower coils.

[0008] As an improvement to the above scheme, the first transmitting coil operates at a first frequency, the second transmitting coil operates at a second frequency, and the third transmitting coil operates at a third frequency.

[0009] In this scheme, the first, second, and third transmitting coils are set with different frequencies to facilitate the differentiation of the magnetic fields generated by the corresponding transmitting coils in the x-axis, y-axis, and z-axis directions during detection, and to determine the posture of the plate-shaped metal object by the magnetic fields in the corresponding directions.

[0010] Preferably, the upper coil and the lower coil are electrically connected.

[0011] Optionally, the upper and lower coils are electrically disconnected.

[0012] Secondly, the present invention provides a method for recognizing the posture of a plate-shaped metal object, employing the coil structure of the aforementioned through-type detector. The method includes the following steps:

[0013] A plate-shaped metal object passes through the middle channel, and the receiving coil receives signals containing a first frequency, a second frequency, and a third frequency.

[0014] Selectively acquire signals at a first frequency, a second frequency, and a third frequency, and extract data from the first frequency, the second frequency, and the third frequency signals respectively;

[0015] Select the largest data point;

[0016] The maximum data is extracted from one of the frequency signals while the data of the other two frequency signals are very small. The transmitting coil corresponding to that frequency generates a magnetic field in the corresponding direction that passes through the maximum cross-section of the metal object. It is determined that the object being tested is a plate-shaped metal object and passes through in an attitude perpendicular to the direction of the maximum cross-section of the plate-shaped metal object.

[0017] As an improvement to the above solution, the method is specifically as follows:

[0018] The maximum data is extracted from the first frequency signal. The data of the second and third frequency signals are very small. The magnetic field in the z-axis direction passes through the maximum cross section of the metal object. It can be determined that the object being tested is a plate-shaped metal object, and it passes through the maximum cross section of the plate-shaped metal object in an attitude that is perpendicular to the z-axis (parallel to the ground).

[0019] As an improvement to the above solution, the method is specifically as follows:

[0020] The maximum data is extracted from the second frequency signal. The data of the first and third frequency signals are very small. The magnetic field in the x-axis direction passes through the maximum cross section of the metal object. It can be determined that the object being tested is a plate-shaped metal object, and it passes through the maximum cross section of the plate-shaped metal object in an attitude perpendicular to the x-axis (parallel to the door panel).

[0021] As an improvement to the above solution, the method is specifically as follows:

[0022] The maximum data is extracted from the third frequency signal. The data of the first and second frequency signals are very small. The magnetic field in the y-axis direction passes through the maximum cross section of the metal object. It can be determined that the object being tested is a plate-shaped metal object, and it passes through the maximum cross section of the plate-shaped metal object in an orientation that is perpendicular to the y-axis (parallel to the abdomen).

[0023] As an improvement to the above scheme, the method further includes displaying the attitude information detection results through text and / or images. Optionally, the data of the first frequency signal, the second frequency signal, and the third frequency signal are selected from one or any combination of metal strength value, metal phase value, and metal phase fluctuation value.

[0024] Thirdly, the present invention also provides a through-type detector, which includes

[0025] The coil structure of the through-type detector described above;

[0026] A signal receiving unit is used to receive signals containing a first frequency, a second frequency, and a third frequency;

[0027] The frequency selection unit is used to selectively acquire signals of a first frequency, a second frequency, and a third frequency.

[0028] The extraction unit is used to extract data from the first frequency signal, the second frequency signal, and the third frequency signal;

[0029] The comparison unit is used to select the largest data point;

[0030] The judgment unit is used when the maximum data is extracted from one of the frequency signals, while the data of the other two frequency signals are very small. The transmitting coil of the corresponding frequency generates a magnetic field in the corresponding direction that passes through the maximum cross section of the metal object, and determines that the object being tested is a plate-shaped metal object, and that it passes through the maximum cross section of the plate-shaped metal object in an attitude perpendicular to the direction stated therein.

[0031] As an improvement to the above scheme, the judgment unit also includes

[0032] The first judgment unit is used to identify that when the maximum data is extracted from the first frequency signal, the data of the second and third frequency signals are very small, and the magnetic field in the z-axis direction passes through the maximum cross section of the metal object. It is then determined that the object being tested is a plate-shaped metal object, and that it passes through the object with the maximum cross section of the plate-shaped metal object parallel to the ground.

[0033] As an improvement to the above scheme, the judgment unit also includes

[0034] The second judgment unit is used to identify that when the maximum data is extracted from the second frequency signal, the data of the first frequency signal and the third frequency signal are very small, and the magnetic field in the x-axis direction passes through the maximum cross section of the metal object. It is then determined that the object being tested is a plate-shaped metal object, and that it passes through the plate-shaped metal object with the maximum cross section being parallel to the door panel.

[0035] As an improvement to the above scheme, the judgment unit also includes

[0036] The third judgment unit is used to identify that when the maximum data is extracted from the third frequency signal, the data of the first frequency signal and the second frequency signal are very small. The magnetic field in the y-axis direction passes through the maximum cross section of the metal object, which can determine that the object being tested is a plate-shaped metal object, and that it passes through the plate-shaped metal object with the maximum cross section parallel to the abdomen.

[0037] As an improvement to the above solution, the detector further includes a display unit for displaying the attitude information detection results through text and / or images. Optionally, the data of the first frequency signal, the second frequency signal, and the third frequency signal are selected from one or any combination of metal strength value, metal phase value, and metal phase fluctuation value.

[0038] Beneficial effects

[0039] The coil structure of this through-type detector generates electromagnetic fields in the y and z directions in the middle channel through the upper and lower coils of the first transmitting line. The second transmitting coils on both sides generate a stronger electromagnetic field in the x direction. The magnetic fields of the third transmitting coils on both sides are relatively compressed, generating a magnetic field strength in the y-axis direction in the middle part of the channel corresponding to the adjacent positions of the upper and lower coils. This allows a large number of magnetic field lines to pass through the maximum cross-section of the plate-shaped metal object in any of the x, y, and z directions, generating strong eddy current signals and improving the reliability of the coil structure in detecting plate-shaped metal objects. Furthermore, the plate-shaped metal object attitude identification method separates the received signal at different frequencies. The largest data collected at the three frequencies indicates that the receiving coil measures a larger induced signal at the corresponding frequency electromagnetic field. Since the magnetic field lines of the corresponding frequency magnetic field pass through the maximum cross-section of the metal object, it can be determined that the maximum cross-section of the plate-shaped metal object is perpendicular to the magnetic field lines in that specific direction, thus determining the attitude of the plate-shaped metal object and achieving attitude identification. Moreover, the detector possesses various functional modules for attitude identification of plate-shaped metal objects. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the coil structure of a through-type detector provided in Embodiment 1 of the present invention;

[0041] Figure 2 This is a front view of the coil structure of a through-type detector provided in Embodiment 1 of the present invention;

[0042] Figure 3 This is a top view of the coil structure of a through-type detector provided in Embodiment 1 of the present invention.

[0043] Figure 4 This is a bottom view of the coil structure of a through-type detector provided in Embodiment 1 of the present invention;

[0044] Figure 5 This is a schematic diagram of the coil structure of a through-type detector provided in Embodiment 2 of the present invention;

[0045] Figure 6 This is a schematic diagram of the structure of a through-type detector provided in Embodiment 3 of the present invention. Detailed Implementation

[0046] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0047] The plate-shaped metal articles in each embodiment are mobile phones, tablets, copper plates, and other plate-shaped metal articles.

[0048] See Figure 1This is a schematic diagram of the coil structure of a through-type detector 3 according to Embodiment 1 of the present invention. The coil structure includes transmitting coils 1 and 2 arranged opposite each other on both sides, forming a central channel for the passage of the object being measured. Transmitting coil 1 consists of an upper coil 111, a lower coil 112, a transmitting coil 113, and a transmitting coil 114. The upper coil 111 and the lower coil 112 are wound in opposite directions on the same conductor. The upper coil 111 and the lower coil 112 operate at a first frequency, the transmitting coil 113 operates at a second frequency, and the transmitting coil 114 operates at a third frequency. Transmitting coil 2 consists of an upper coil 211, a lower coil 212, a transmitting coil 213, and a transmitting coil 214. The upper coil 211 and the lower coil 212 are wound in opposite directions on the same conductor. The upper coil 211 and the lower coil 212 operate at the first frequency, the transmitting coil 213 operates at the second frequency, and the transmitting coil 214 operates at the third frequency. Transmitting coil 1 and transmitting coil 2 are the same shape and size, and the centers of the two coils coincide, that is, the coil projections overlap.

[0049] The transmitting coils 113 and 213 are energized with a second frequency current. The signals on both sides are 0 degrees out of phase and the normals of the coils on both sides are in the same direction. The magnetic field in the measured area of ​​the middle channel is mainly a magnetic field along the horizontal direction of the x-axis.

[0050] Transmitting coils 114 and 214 are fed with a third frequency current, and the signals on both sides are 180 degrees out of phase. The magnetic field in the measured area of ​​the middle channel is mainly along the y-axis.

[0051] Transmitting coils 111 and 211 are energized with a first-frequency current, and the signals on both sides are 180 degrees out of phase. Transmitting coils 112 and 212 are also energized with a first-frequency current, and the signals on both sides are 180 degrees out of phase. The resulting magnetic field lines of the upper coils on both sides are relatively compressed, causing them to shift towards the y and z axes within the middle channel. The normals of the lower coils on both sides are opposite, forming a larger annular magnetic field within the middle channel. The magnetic field generated in the middle channel is mainly along the y and z axes.

[0052] When the metal plate and the maximum cross-section of the mobile phone are parallel to the x-axis and y-axis, for example, parallel to the ground, the electromagnetic field generated by the first frequency current has the greatest magnetic induction intensity in the z-axis direction of the middle channel. The magnetic field lines pass through the maximum cross-section of the metal plate and the mobile phone, and the eddy current effect is the greatest, which can detect the object under test.

[0053] When the metal plate and the maximum cross-section of the mobile phone are parallel to the y-axis and z-axis, such as when they are parallel to a door panel, the electromagnetic field generated by the second frequency current has the greatest magnetic induction intensity in the x-axis direction of the middle channel. The magnetic field lines pass through the maximum cross-section of the metal plate and the mobile phone, and the eddy current effect is the greatest, which can detect the object under test.

[0054] When the metal plate and the maximum cross-section of the mobile phone are parallel to the x-axis and z-axis, such as parallel to the human abdomen, the electromagnetic field generated by the third frequency current has the greatest magnetic induction intensity in the y-axis direction of the middle channel. The magnetic field lines pass through the maximum cross-section of the metal plate and the mobile phone, and the eddy current effect is the greatest, which can detect the object under test.

[0055] By complementing electromagnetic fields of different frequencies within the measured area, a magnetic field is formed that exists simultaneously in the x, y, and z axes. Therefore, regardless of the posture in which the metal plate or mobile phone passes through the detector, the maximum cross-sectional area of ​​the measured object can generate an effective eddy current effect, greatly improving the detection rate of the measured object.

[0056] If the person being inspected conceals their mobile phone inside a book or document, parallel to the ground (perpendicular to the z-axis and parallel to the x and y axes), and passes through the detection channel, the receiving coil will detect the largest data at the first frequency (z-axis), while the receiving coil will detect smaller data at the second frequency (x-axis) and third frequency (y-axis). This indicates that the object is a plate-shaped item, and the mobile phone passes through the detection channel in an attitude parallel to the ground.

[0057] If a person being inspected conceals a cube-shaped object in the middle of the passage, the detection coil will measure large values ​​in all three directions, indicating that the object is a non-plate-shaped three-dimensional object.

[0058] See Figure 2 This is a front view of the coil structure of a through-type detector provided in Embodiment 1 of the present invention. Transmitting coils 111 and 211, and 112 and 212, are on the same horizontal plane with opposite magnetic field lines on their left and right sides. Within the middle channel, the magnetic field lines deflect towards the z-axis, thus generating a z-axis magnetic field in this region. Transmitting coils 114 and 214 are on the same horizontal plane with opposite magnetic field lines on their left and right sides, generating a z-axis magnetic field in the upper and lower parts of the middle channel.

[0059] Transmitting coil 113 and transmitting coil 213 have magnetic field lines in the same direction at the same level, generating a magnetic field in the x-axis direction in the middle channel, indicated by a hollow arrow.

[0060] See Figure 3 This is a top view of the coil structure of a through-type detector provided in Embodiment 1 of the present invention. Transmitting coils 114 and 214 operate at a third frequency. The magnetic field lines of the left and right coils are in opposite directions, and within the middle channel, the magnetic field lines deflect towards the y-axis, thus generating a y-axis magnetic field in this region, indicated by a dashed arrow. Transmitting coils 111 and 211 operate at a first frequency. The magnetic field lines of the left and right coils are in opposite directions, and within the middle channel, the magnetic field lines deflect towards the y-axis, thus generating a y-axis magnetic field in this region, indicated by a solid triangular arrow.

[0061] See Figure 4 This is a bottom view of the coil structure of a through-type detector provided in Embodiment 1 of the present invention. The transmitting coils 114 and 214 have magnetic field lines in opposite directions on their left and right sides. Within the middle channel, the magnetic field lines deflect towards the y-axis, thus generating a y-axis magnetic field in this region, indicated by a dotted-dash arrow. Similarly, the transmitting coils 112 and 212 have magnetic field lines in opposite directions on their left and right sides. Within the middle channel, the magnetic field lines deflect towards the y-axis, thus generating a y-axis magnetic field in this region, indicated by a solid triangular arrow.

[0062] See Figure 5 This is a schematic diagram of the coil structure of a through-type detector provided in Embodiment 2 of the present invention. This embodiment is based on Embodiment 1, except that the upper coil 111 and the lower coil 112 of the transmitting coil 1 are electrically disconnected, and the upper coil 211 and the lower coil 212 of the transmitting coil 2 are electrically disconnected. The two embodiments operate on the same principle.

[0063] Embodiment 3 of the present invention provides a method for attitude recognition of a plate-shaped metal object, which uses the coil structure of the through-type detector of Embodiment 1 as the implementation environment. The method includes the following steps:

[0064] S1: A plate-shaped metal object passes through the middle channel, and the receiving coil receives signals containing the first frequency, the second frequency, and the third frequency.

[0065] S2: Selectively acquire signals at the first, second, and third frequencies, and extract the first amplitude of the first frequency signal, the second amplitude of the second frequency signal, and the third amplitude of the third frequency signal, respectively.

[0066] The first amplitude, second amplitude, and third amplitude are the metal strength values. In an optional embodiment, the first phase of the first frequency signal, the second phase of the second frequency signal, and the third phase of the third frequency signal are extracted respectively. In another optional embodiment, the first phase fluctuation value of the first frequency signal, the second phase fluctuation value of the second frequency signal, and the third phase fluctuation value of the third frequency signal are extracted respectively.

[0067] S3: Select the data with the largest amplitude.

[0068] S4: When the largest data is the first amplitude, the values ​​of the second and third amplitudes are very small. This corresponds to the magnetic field in the z-axis direction passing through the largest cross section of the metal object. It can be determined that the object being tested is a plate-shaped metal object, and it passes through the object with the largest cross section of the plate-shaped metal object perpendicular to the z-axis, i.e., parallel to the ground.

[0069] S5: When the largest data is the second amplitude, the values ​​of the first and third amplitudes are very small. The magnetic field in the x-axis direction passes through the largest cross section of the metal object. It can be determined that the object being tested is a plate-shaped metal object, and it passes through in an attitude where the largest cross section of the plate-shaped metal object is perpendicular to the x-axis, that is, parallel to the door panel.

[0070] S6: When the largest data is the third amplitude, the values ​​of the first and second amplitudes are very small. The magnetic field in the y-axis direction passes through the largest cross section of the metal object. It can be determined that the object being tested is a plate-shaped metal object, and it passes through the object with the largest cross section of the plate-shaped metal object perpendicular to the y-axis, that is, parallel to the abdomen of the person being tested.

[0071] Embodiment 3 of the present invention provides a walk-through detector. The detector includes the coil structure of the walk-through detector of Embodiment 1, a signal receiving unit 310, a frequency selection unit 320, an extraction unit 330, a comparison unit 340, a judgment unit 350, and a display unit 360.

[0072] The signal receiving unit is used to receive signals containing a first frequency, a second frequency, and a third frequency.

[0073] The frequency selection unit is used to select and acquire signals of the first frequency, the second frequency, and the third frequency.

[0074] The extraction unit is used to extract data from the first frequency signal, the second frequency signal, and the third frequency signal.

[0075] The comparison unit is used to select the largest data.

[0076] The judgment unit includes a first judgment unit, a second judgment unit, and a third judgment unit.

[0077] The display unit is used to display the attitude information detection results through text and / or images.

[0078] The first judgment unit 351 is used to identify that when the maximum data is extracted from the first frequency signal, the data of the second frequency signal and the third frequency signal are very small, and the magnetic field in the z-axis direction passes through the maximum cross section of the metal object. It can be determined that the object being tested is a plate-shaped metal object, and it passes through the maximum cross section of the plate-shaped metal object in an attitude perpendicular to the z-axis.

[0079] The second judgment unit 352 is used to identify that when the maximum data is extracted from the second frequency signal, the data of the first frequency signal and the third frequency signal are very small, and the magnetic field in the x-axis direction passes through the maximum cross section of the metal object. It can be determined that the object being tested is a plate-shaped metal object, and it passes through the maximum cross section of the plate-shaped metal object in an attitude perpendicular to the x-axis.

[0080] The third judgment unit 353 is used to identify that when the maximum data is extracted from the third frequency signal, the data of the first frequency signal and the second frequency signal are very small, and the magnetic field in the y-axis direction passes through the maximum cross section of the metal object. It can be determined that the object being tested is a plate-shaped metal object, and it passes through the maximum cross section of the plate-shaped metal object in an attitude perpendicular to the y-axis.

[0081] In this embodiment, the through-type detector receiving unit (not shown) receives the signal. The frequency selection unit separates the signals of different frequencies. The extraction unit extracts data corresponding to the first frequency signal, the second frequency signal, and the third frequency signal, including the metal strength value, the metal phase value, and the metal phase fluctuation value, either individually or in any combination. The comparison unit calculates the maximum data. The judgment unit identifies that the maximum data is extracted from one of the frequency signals while the data of the other two frequency signals are very small. The transmitting coil corresponding to that frequency generates a magnetic field in the corresponding direction that passes through the maximum cross-section of the metal object. It is determined that the object being tested is a plate-shaped metal object, and that it passes through in an attitude perpendicular to the maximum cross-section of the plate-shaped metal object in the stated direction. The through-type detector and the plate-shaped metal object attitude recognition method provided in the above embodiment belong to the same concept. The specific implementation process is detailed in the method embodiment and will not be repeated here.

[0082] It should be noted that the above is only an example of the division of the functional modules of the through-type detector in the embodiment. In actual applications, the above functions can be assigned to different functional modules as needed.

[0083] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0084] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. Coil structure for a search coil, characterized in that include: It includes two opposing sets of transmitting coils, with an intermediate channel between them for the object being measured to pass through; Each of the two-sided transmitting coil groups includes a first transmitting coil, a second transmitting coil, and a third transmitting coil; the first transmitting coil includes an upper coil and a lower coil, and the first transmitting coil is respectively arranged in the area enclosed by the second transmitting coil and the third transmitting coil; The normals of the second transmitting coils on both sides are in the same direction, while the normals of the third transmitting coils on both sides are in opposite directions. The normal directions of the upper and lower coils on one side are opposite at the same time, and the normal directions of the two upper coils of the double-sided transmitting coil group are opposite at the same time; the first transmitting coil operates at the first frequency, the second transmitting coil operates at the second frequency, and the third transmitting coil operates at the third frequency.

2. The coil structure of a through-type probe according to claim 1, wherein Within the three-dimensional space of the central channel, electromagnetic fields are formed in three directions: x, y, and z. The x-direction is perpendicular to the door panel, the y-direction is the direction through the central channel, and the z-direction is perpendicular to the ground. The x, y, and z directions are mutually perpendicular.

3. The coil structure of a through-type probe according to claim 1 or 2, wherein The upper and lower coils are electrically connected.

4. The coil structure of a through-type probe according to claim 1 or 2, wherein The upper and lower coils are electrically disconnected.

5. A method for recognizing the posture of a plate-like metal article using the coil structure of the through-type probe according to claim 1, characterized by, The method includes the following steps: A plate-shaped metal object passes through the middle channel, and the receiving coil receives signals containing a first frequency, a second frequency, and a third frequency. Selectively acquire signals at a first frequency, a second frequency, and a third frequency, and extract data from the first frequency, the second frequency, and the third frequency signals respectively; Select the largest data point; The maximum data is extracted from one of the frequency signals while the data of the other two frequency signals are very small. The transmitting coil corresponding to that frequency generates a magnetic field in the corresponding direction that passes through the maximum cross-section of the metal object. It is determined that the object being tested is a plate-shaped metal object and passes through in an attitude perpendicular to the direction of the maximum cross-section of the plate-shaped metal object.

6. The method according to claim 5, wherein the plate-like metal article is a steel sheet. The maximum data is extracted from one frequency signal while the data of the other two frequency signals are very small. The transmitting coil corresponding to that frequency generates a magnetic field in the corresponding direction that passes through the maximum cross-section of the metal object. The specific steps for determining that the tested object is a plate-shaped metal object and that it passes through in an orientation perpendicular to the maximum cross-section of the plate-shaped metal object are as follows: The maximum data is extracted from the first frequency signal. The data of the second and third frequency signals are very small. The magnetic field in the z-axis direction passes through the maximum cross section of the metal object. It can be determined that the object being tested is a plate-shaped metal object, and it passes through the maximum cross section of the plate-shaped metal object in an orientation perpendicular to the z-axis.

7. The method according to claim 5, wherein the step of determining the attitude of the plate-like metal article is performed by using a plurality of cameras. The maximum data is extracted from one frequency signal while the data of the other two frequency signals are very small. The transmitting coil corresponding to that frequency generates a magnetic field in the corresponding direction that passes through the maximum cross-section of the metal object. The specific steps for determining that the tested object is a plate-shaped metal object and that it passes through in an orientation perpendicular to the maximum cross-section of the plate-shaped metal object are as follows: The maximum data is extracted from the second frequency signal. The data of the first and third frequency signals are very small. The magnetic field in the x-axis direction passes through the maximum cross-section of the metal object. It can be determined that the object being tested is a plate-shaped metal object, and it passes through the maximum cross-section of the plate-shaped metal object in an attitude perpendicular to the x-axis.

8. The method according to claim 5, wherein the plate-like metal article is a steel sheet. The maximum data is extracted from one of the frequency signals, and the data of the other two frequency signals is very small, a magnetic field corresponding to the frequency is generated by the transmission coil in the corresponding direction to pass through the maximum cross section of the metal object, and it is determined that the measured object is a plate-shaped metal object and passes through in an attitude in which the maximum cross section of the plate-shaped metal object is perpendicular to the direction. The maximum data is extracted from the third frequency signal, the data of the first frequency signal and the second frequency signal is very small, a magnetic field corresponding to the y-axis direction passes through the maximum cross section of the metal object, and it is determined that the measured object is a plate-shaped metal object and passes through in an attitude in which the maximum cross section of the plate-shaped metal object is perpendicular to the y-axis.

9. The method according to any one of claims 5 to 7, wherein the plate-like metal article is a steel sheet. The data of the first frequency signal, the second frequency signal, and the third frequency signal is one or any combination of a metal strength value, a metal phase value, and a metal phase fluctuation value.

10. The method according to any one of claims 5 to 7, wherein Further comprising The attitude information detection result is displayed through text and / or images.

11. A through-probe, characterized by Comprising The coil structure of the through-type detector of claim 1; A signal receiving unit for receiving a signal containing a first frequency, a second frequency, and a third frequency for detecting a plate-shaped metal object; A frequency selection unit for selecting a signal of the first frequency, a signal of the second frequency, and a signal of the third frequency; An extraction unit for extracting data of the first frequency signal, the second frequency signal, and the third frequency signal; A comparison unit for selecting the maximum data; A judgment unit for determining that the measured object is a plate-shaped metal object and passes through in an attitude in which the maximum cross section of the plate-shaped metal object is perpendicular to the direction of the magnetic field corresponding to the frequency when the maximum data is extracted from one of the frequency signals and the data of the other two frequency signals is very small.

12. The through-type probe of claim 11, wherein, The judgment unit comprises A first judgment unit for identifying that the maximum data is extracted from the first frequency signal, the data of the second frequency signal and the third frequency signal is very small, a magnetic field corresponding to the z-axis direction passes through the maximum cross section of the metal object, and it is determined that the measured object is a plate-shaped metal object and passes through in an attitude in which the maximum cross section of the plate-shaped metal object is perpendicular to the z-axis.

13. The through-type probe of claim 11, wherein, The judgment unit comprises A second judgment unit for identifying that the maximum data is extracted from the second frequency signal, the data of the first frequency signal and the third frequency signal is very small, a magnetic field corresponding to the x-axis direction passes through the maximum cross section of the metal object, and it is determined that the measured object is a plate-shaped metal object and passes through in an attitude in which the maximum cross section of the plate-shaped metal object is perpendicular to the x-axis.

14. The through-type probe of claim 11, wherein, The judgment unit comprises A third judgment unit for identifying that the maximum data is extracted from the third frequency signal, the data of the first frequency signal and the second frequency signal is very small, a magnetic field corresponding to the y-axis direction passes through the maximum cross section of the metal object, and it is determined that the measured object is a plate-shaped metal object and passes through in an attitude in which the maximum cross section of the plate-shaped metal object is perpendicular to the y-axis.

15. The through-type probe of claim 11, wherein, Further comprising A display unit for displaying the attitude information detection result through text and / or images.

16. The through-type probe according to any one of claims 11 to 13, wherein The data of the first frequency signal, the second frequency signal, and the third frequency signal is one or any combination of a metal strength value, a metal phase value, and a metal phase fluctuation value.

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