Panel and security inspection apparatus

Abstract

A panel and a security inspection apparatus. The panel comprises: a panel body (100) and at least two detection modules (110) sequentially arranged on the panel body (100). Each detection module (110) comprises: a fundamental-frequency transmitting unit (111) for transmitting a fundamental-frequency signal and a harmonic receiving unit (112) for receiving a harmonic signal. A harmonic receiving unit (112) of at least one detection module (110) is configured for receiving a harmonic signal corresponding to a fundamental-frequency signal transmitted by a fundamental-frequency transmitting unit (111) in the detection module (110) where the harmonic receiving unit is located, and for receiving a harmonic signal corresponding to a fundamental-frequency signal transmitted by a fundamental-frequency transmitting unit (111) in at least one other detection module (110).

Description

Door panel and security inspection device

[0001] The present application claims priority to the Chinese patent application No. 2024115299325, filed on October 30, 2024, entitled "Door panel and security inspection door" and the Chinese patent application No. 202510732747.4, filed on June 3, 2025, entitled "Door panel and security inspection device", both of which are incorporated herein by reference in their entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of security inspection, more particularly, to a door panel and a security inspection device. BACKGROUND

[0003] The walkthrough security inspection door is mainly applied in public places with large number of people, such as airports, stations and large conferences. The working principle is mainly to use eddy current detection technology to identify hidden metal objects, such as guns and controlled knives, in the walkthrough security inspection door to identify dangerous objects therein. However, the detection effect of the traditional walkthrough security inspection door on electronic devices containing little or no metal is poor.

[0004] The non-linear junction detection technology can detect electronic devices. If this technology is applied to the walkthrough security inspection door, how to reduce the detection blind area is a problem to be solved when the walkthrough security inspection door conducts safety detection. SUMMARY

[0005] Therefore, it is necessary to provide a door panel, which comprises a door panel body and at least two detection modules on the door panel body. The detection module comprises a fundamental wave transmitting unit for transmitting a fundamental wave signal and a harmonic wave receiving unit for receiving a harmonic wave signal. The harmonic wave receiving unit of at least one detection module is used to receive the harmonic wave signal corresponding to the fundamental wave signal transmitted by the fundamental wave transmitting unit in the detection module, and to receive the harmonic wave signal corresponding to the fundamental wave signal transmitted by the fundamental wave transmitting unit in at least one other detection module.

[0006] A security inspection device comprises a door panel. The door panel comprises a door panel body and at least two detection modules on the door panel body. The detection module comprises a fundamental wave transmitting unit for transmitting a fundamental wave signal and a harmonic wave receiving unit for receiving a harmonic wave signal. The harmonic wave receiving unit of at least one detection module is used to receive the harmonic wave signal corresponding to the fundamental wave signal transmitted by the fundamental wave transmitting unit in the detection module, and to receive the harmonic wave signal corresponding to the fundamental wave signal transmitted by the fundamental wave transmitting unit in at least one other detection module.

[0007] Details of one or more embodiments of this application are set forth in the following drawings and description. Other features, objects, and advantages of the invention will become apparent from the specification, drawings, and claims. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained from these drawings without creative effort.

[0009] Figure 1 is a structural schematic diagram of the first type of door panel provided in an embodiment of the present invention;

[0010] Figure 2 is a structural schematic diagram of the second type of door panel provided in an embodiment of the present invention;

[0011] Figure 3 is a schematic diagram of the radiation of the security gate in the direction of gravity in the related technology;

[0012] Figure 4 is a schematic diagram of the radiation of the security inspection device provided in the embodiment of the present invention along the direction of gravity;

[0013] Figure 5 is a schematic diagram of a security gate in related technologies when a user carrying the object to be tested just enters the detection area.

[0014] Figure 6 is a schematic diagram of a user moving the object to be tested to the boundary of the detection area in a security gate in related technologies;

[0015] Figure 7 is a schematic diagram of a security gate in related technologies when the user moves outside the detection area;

[0016] Figure 8 is a structural schematic diagram of the third type of door panel provided in an embodiment of the present invention;

[0017] Figure 9 is a structural schematic diagram of the fourth type of door panel provided in an embodiment of the present invention;

[0018] Figure 10 is a structural schematic diagram of the fifth type of door panel provided in an embodiment of the present invention;

[0019] Figure 11 is a schematic diagram of the object being tested just entering the detection area of ​​the security inspection device provided in this embodiment of the invention;

[0020] Figure 12 is a schematic diagram showing the object being tested located in the middle of the detection area of ​​the security inspection device provided in this embodiment of the invention;

[0021] Figure 13 is a schematic diagram of a user moving with the object to be tested to the boundary of the detection area of ​​the security inspection device provided in this embodiment of the invention.

[0022] Reference numerals: 100, door panel body; 110, detection module; 111, fundamental wave transmitting unit; 112, harmonic receiving unit; 1121, first receiving unit; 1122, second receiving unit; 1123, third receiving unit. Detailed Implementation

[0023] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0025] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," just as "comprising" is interpreted as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

[0026] Nonlinear node detection technology can be applied to security gates. Multiple nonlinear node detection modules can be arranged along a specific direction (e.g., the height) of the gate panel, forming multiple detection zones along the height. When an object passes through the gate's detection channel, it can be detected and identified to confirm whether it is a suspicious item containing nonlinear nodes. However, the harmonic receiving unit inside the security gate is limited by its hardware (e.g., the receiving antenna), resulting in a limited receiving angle. When the spacing between two nonlinear node detection modules is large, if the object passes through the detection channel and happens to be located in the corresponding interval area, it may not be detected, creating a detection blind spot and leading to a high false negative rate for the security gate.

[0027] Figures 1 and 4 show schematic diagrams of a door panel according to an embodiment of the present invention. It should be noted that this door panel can be used in various security inspection devices, such as the security inspection device shown in Figure 4. The security inspection device has a detection channel for people to pass through. When a person passes through, the items they are carrying can be inspected.

[0028] In some embodiments, the door panel may include a door panel body 100 and at least two detection modules 110 on the door panel body 100. The detection modules 110 may be arranged in the direction of gravity or in the horizontal direction (i.e., the direction of movement of a person in the detection channel).

[0029] The detection module 110 may include a fundamental wave transmitting unit 111 for transmitting a fundamental wave signal and a harmonic receiving unit 112 for receiving harmonic signals. The harmonic receiving unit 112 is used to receive the harmonic signal corresponding to the fundamental wave signal transmitted by the fundamental wave transmitting unit 111 in its detection module 110, and to receive the harmonic signal corresponding to the fundamental wave signal transmitted by at least one other detection module 110's fundamental wave transmitting unit 111.

[0030] It should be noted that the detection module 110 mentioned in all embodiments of the present invention can be a nonlinear node detection module, used to detect hidden eavesdropping devices, detonation circuits, and other electronic devices containing nonlinear nodes within the tested area. Specifically, the detection module 110 can transmit a fundamental wave signal to the tested area. When an electronic device containing a nonlinear node exists within the tested area, the nonlinear node will generate and radiate a harmonic signal corresponding to the fundamental wave signal under the influence of the fundamental wave signal. The detection module 110 can receive this harmonic signal and make a judgment based on the received harmonic signal, thereby obtaining a judgment result on whether a nonlinear node exists in the tested area. It should be noted that the "harmonic signal corresponding to the fundamental wave signal" below refers to the harmonic signal radiated by the nonlinear node after the fundamental wave signal is transmitted to it.

[0031] In this embodiment, each detection module 110, divided according to the function of the circuit modules, includes an independent fundamental wave transmitting unit 111 and a harmonic receiving unit 112. The fundamental wave transmitting unit 111 of each detection module 110 can transmit a fundamental wave signal. At least one harmonic receiving unit 112 in one detection module 110 can receive not only the harmonic signal corresponding to the fundamental wave signal transmitted by the fundamental wave transmitting unit 111 in its own detection module 110, but also the harmonic signal corresponding to the fundamental wave signal transmitted by at least one other detection module 110's fundamental wave transmitting unit 111. This broadens the frequency band range of the signals received by the harmonic receiving unit 112, effectively increasing the coverage area of ​​the detection region of the harmonic receiving unit 112 and thus reducing the range of the blind zone. Therefore, through this embodiment, in practical applications, the range of the detection blind zone can be reduced without increasing the number of detection modules 110, so that the detection channel is covered as much as possible by the detection areas corresponding to the multiple detection modules 110 on the door panel body 100, thereby reducing the range of the detection blind zone of the security inspection device and thus reducing the false alarm rate during the detection process.

[0032] It should be noted that the coverage area of ​​the detection area mentioned in this embodiment refers to the area that can be effectively detected within the security checkpoint. In related technologies, harmonic receiving units can only receive harmonic signals corresponding to their respective detection modules, and the intensity of the harmonic signal is related to the location of the object being tested (i.e., the closer the object is to the detection module 110, the stronger the harmonic signal). Therefore, each harmonic receiving unit can only detect an area relatively close to its own detection module, meaning the area that a harmonic receiving unit can effectively detect within the security checkpoint is relatively small. However, the harmonic receiving unit 112 provided in this embodiment can also receive harmonic signals corresponding to other detection modules 110. Thus, for this harmonic receiving unit 112, an object can be detected when it is close to its own detection module 110, and it can also be detected when it is close to other detection modules 110 and also close to the harmonic receiving unit 112. This effectively increases the coverage area of ​​the harmonic receiving unit 112 within the detection channel, thereby reducing the false negative rate. Therefore, this solution can effectively reduce the range of the blind zone by widening the receiving bandwidth of the harmonic receiving unit 112.

[0033] Furthermore, in the embodiments of this application, the harmonic receiving unit 112 can receive a second harmonic signal radiated by the object under test, a third harmonic signal radiated by the object under test, or both second and third harmonic signals simultaneously. It should be noted that the frequencies of the harmonic signals corresponding to the fundamental signal are multiples of the fundamental signal frequency; for example, the frequency of the second harmonic signal is twice the frequency of the fundamental signal, and the frequency of the third harmonic signal is three times the frequency of the fundamental signal.

[0034] In one example, at least one harmonic receiving unit 112 of a detection module 110 can receive the harmonic signal corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit 111 in its own detection module 110, as well as the harmonic signal corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit 111 of a detection module 110 adjacent to the detection module 110 (e.g., the fundamental wave transmitting unit 111 in a detection module 110 located above or below the detection module 110 in the direction of gravity), or the harmonic signal corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit 111 of a detection module 110 that is far away from the detection module 110 (e.g., separated by one or more detection modules 110).

[0035] In another example, at least one harmonic receiving unit 112 of a detection module 110 can receive harmonic signals corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit 111 in its own detection module 110, as well as harmonic signals corresponding to the fundamental wave signal emitted by the fundamental wave transmitting units 111 of multiple other detection modules 110. That is, the detection module 110 can receive harmonic signals corresponding to the fundamental wave signal emitted by the fundamental wave transmitting units 111 of more than two detection modules 110. For example, the harmonic receiving unit 112 of the detection module 110 can receive harmonic signals corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit 111 of a detection module 110 adjacent to it, and simultaneously receive harmonic signals corresponding to the fundamental wave signal emitted by the fundamental wave transmitting units 111 of detection modules 110 that are farther away (e.g., separated by one or more detection modules 110). This scheme further expands the detection area corresponding to the detection module 110, thereby reducing the range of the detection blind zone.

[0036] It should be noted that if the harmonic receiving unit 112 can simultaneously receive harmonic signals corresponding to multiple detection modules 110 arranged along the direction of gravity (i.e., the height direction of the door panel body 100), the detection blind zone along the direction of gravity can be reduced. Alternatively, if the harmonic receiving unit 112 can simultaneously receive harmonic signals corresponding to multiple detection modules 110 arranged along the direction of human movement within the detection channel, the detection blind zone along the direction of movement can be reduced. The direction of movement is perpendicular to the direction of gravity.

[0037] It should be noted that the number of harmonic signals received by the harmonic receiving units 112 in different detection modules 110 can be the same (e.g., all harmonic receiving units 112 in detection modules 110 receive the harmonic signals of their own detection module 110 and the harmonic signals of another detection module 110), or they can be different. For example, some receive only the harmonic signals of their own detection module 110, some receive the harmonic signals of two detection modules 110 (including their own detection module 110), and some receive the harmonic signals of more than two detection modules 110 (including their own detection module 110). All of these are within the scope of protection of this application.

[0038] In one specific embodiment, the harmonic receiving unit 112 can receive harmonic signals from multiple detection modules 110 by setting appropriate receiving parameters (such as receiving bandwidth and center frequency). As shown in Figure 2, taking the example that the harmonic receiving unit 112 in detection module 110A can simultaneously receive the second harmonic signal (frequency f1) corresponding to detection module 110A and the second harmonic signal (frequency f2) corresponding to detection module 110B, the center frequency of the harmonic receiving unit 112 in detection module 110A can be between f1 and f2, for example, equal to the average of f1 and f2, and the receiving bandwidth can simultaneously cover f1 and f2.

[0039] Based on the previous embodiment, as shown in Figure 2, taking the example that the harmonic receiving unit 112 in the detection module 110A can simultaneously receive the third harmonic signal (frequency f3) corresponding to the detection module 110A and the third harmonic signal (frequency f4) corresponding to the detection module 110B. The harmonic receiving unit 112 in the detection module 110A may include a first receiving antenna (not shown in the figure) and a second receiving antenna (not shown in the figure), wherein the receiving bandwidth of the first receiving antenna can simultaneously cover f1 and f2, and the center frequency point is between f1 and f2 (for example, equal to the average value of f1 and f2). Furthermore, the receiving bandwidth of the second receiving antenna can simultaneously cover f3 and f4, and the center frequency point is between f3 and f4 (for example, equal to the average value of f3 and f4). The first and second receiving antennas can be activated in a time-division multiplexing manner or simultaneously.

[0040] In one embodiment of the present invention, the fundamental wave signals emitted by the fundamental wave transmitting units 111 of at least two detection modules 110 have different frequencies, and the harmonic signals corresponding to the at least two fundamental wave signals with different frequencies are received by the harmonic receiving unit 112 in one of the detection modules 110.

[0041] Specifically, the fundamental frequency of all detection modules 110 can be different from each other, meaning the frequency of the fundamental frequency of any one detection module 110 is different from the frequency of the fundamental frequency of the other detection modules 110. Alternatively, only in a portion of the detection modules 110, the frequency of the fundamental frequency of any one detection module 110 is different from the frequency of the fundamental frequency of the other detection modules 110 in that portion, while the frequency of the fundamental frequency of the other portion of the detection modules 110 is not restricted. For example, if there are 10 detection modules 110 in total, then 3 detection modules 110 have fundamental frequency differences, and the other 7 detection modules 110 all have the same fundamental frequency (or the frequency of the fundamental frequency of any one of these 7 detection modules 110 is the same as the frequency of the fundamental frequency of at least one of the other 6 detection modules 110).

[0042] When the detection module 110 is working, multiple harmonic signals of the same frequency propagate in space and may superimpose on each other, which may cause the signal strength of the harmonic signals to be unstable, thereby interfering with the detection process. Therefore, in the embodiments of the present invention, the fundamental wave transmitting units 111 of at least two detection modules 110 may be configured to transmit fundamental wave signals with different frequencies, so that when these detection modules 110 are working simultaneously, they will not interfere with each other.

[0043] Meanwhile, in this embodiment, harmonic signals corresponding to at least two fundamental wave signals with different frequencies are received by the same harmonic receiving unit 112. In other words, at least one harmonic receiving unit 112 receives two or more harmonic signals of different frequencies. For example, if the fundamental wave signals of detection modules 110A, 110B, and 110C have different frequencies, then: the harmonic receiving unit 112 of detection module 110A can simultaneously receive the harmonic signals of detection modules 110A and 110B, or it can simultaneously receive the harmonic signals of detection modules 110A, 110B, and 110C, without restriction on detection modules 110B and 110C. Alternatively, the harmonic receiving unit 112 of detection module 110A can simultaneously receive the harmonic signals of detection modules 110A and 110B, and the harmonic receiving unit 112 of detection module 110B can simultaneously receive the harmonic signals of detection modules 110B and 110C, without restriction on detection module 110C.

[0044] The above solution also avoids the harmonic receiving unit 112 from causing problems for the subsequent signal processing end (e.g., central control module, processor, computing chip, etc.) when it receives harmonic signals corresponding to the fundamental wave signals emitted by the fundamental wave transmitting units 111 of two or more detection modules 110. For example, when the fundamental wave signals of different detection modules 110 have the same frequency, the frequencies of the second and third harmonic signals corresponding to the fundamental wave signals are also the same. The detection module 110 may not be able to distinguish which detection module 110 the harmonic signal specifically corresponds to. Consequently, during the harmonic processing, it will affect the amount of computation, computation time, and computational complexity of the signal processing end, and thus affect the detection efficiency of the entire security inspection device. In this embodiment, in order to overcome the above problems, the frequencies of the fundamental wave signals emitted by at least two detection modules 110 are set to different values. Since the signal frequency of the harmonic signal is a multiple of the fundamental wave signal, the signal frequencies of the harmonic signals will also differ significantly depending on the signal frequency of the fundamental wave signal. Therefore, when the harmonic receiving unit 112 receives harmonic signals corresponding to the fundamental signals emitted by two different detection modules 110, it can quickly determine which detection module 110 the harmonic signal corresponds to based on the frequency of the harmonic signal. Thus, the solution provided in this embodiment reduces the range of the detection blind zone while also reducing the difficulty of identifying harmonic signals and improving the detection efficiency of the entire detection process.

[0045] It should be noted that when the fundamental frequencies of the two fundamental signals are different, for example, if the frequencies of the two fundamental signals are separated by a preset value (which can be understood as a preset frequency bandwidth), the frequencies of the corresponding harmonic signals will be spaced out by a factor of two. For example, if the frequencies of the two fundamental signals are 2000MHz and 2100MHz, the corresponding second harmonic signals will have a frequency difference of twice the preset value, i.e., a frequency difference of 200MHz. The corresponding third harmonic signals of the two fundamental signals will have a frequency difference of three times the preset value, i.e., a frequency difference of 300MHz. Therefore, the frequency spacing between the harmonic signals increases exponentially, making it easier for the detection module 110 to distinguish which detection module 110 corresponds to each harmonic signal when processing the harmonic signals.

[0046] In one embodiment of the present invention, there are multiple detection modules 110 arranged along the direction of gravity, and the fundamental wave signals emitted by the fundamental wave transmitting units 111 of any two adjacent detection modules 110 are at different frequencies. By providing multiple detection modules 110 arranged along the direction of gravity on the door panel body 100, the detection range along the direction of gravity within the detection channel is increased due to the increased number of detection modules 110. Furthermore, since the fundamental wave signals emitted by the fundamental wave transmitting units 111 of any two adjacent detection modules 110 are at different frequencies, and adjacent detection modules 110 are relatively close together, the possibility of receiving each other's harmonic signals is relatively high, making interference more likely. Therefore, this embodiment can avoid mutual interference between adjacent detection modules 110 and facilitates the distinction of received harmonic signals by the harmonic receiving unit 112.

[0047] Furthermore, the harmonic receiving unit 112 is used to receive the harmonic signals corresponding to the fundamental wave signals emitted by the fundamental wave transmitting unit 111 within its own detection module 110, and to receive the harmonic signals corresponding to the fundamental wave signals emitted by the fundamental wave transmitting unit 111 within an adjacent detection module 110. For example, the fundamental wave signal emitted by the fundamental wave transmitting unit 111 in a certain detection module 110 has a frequency of F1, and the corresponding second and third harmonic signals are 2F1 and 3F1, respectively. The fundamental wave signal emitted by the fundamental wave transmitting unit 111 in an adjacent detection module 110 has a frequency of F2, and the corresponding second and third harmonic signals are 2F2 and 3F2, respectively. When receiving harmonic signals, the detection module 110 can determine which detection module 110's fundamental wave transmitting unit 111 emitted the harmonic signal based on whether the received harmonic signal is 2F1 and 3F1 or 2F2 and 3F2.

[0048] In embodiments of the present invention, when multiple detection modules 110 are arranged along the direction of gravity, the frequency of the fundamental wave signal emitted by the fundamental wave transmitting unit 111 of all detection modules 110 can be set to decrease or increase sequentially along the direction of gravity. For example, the frequency of the fundamental wave signal corresponding to each detection module 110 can be set to gradually decrease or increase in the direction of gravity according to a preset step, so as to facilitate the setting of the signal frequency of the fundamental wave signal corresponding to each detection module 110, while avoiding mutual interference during the operation of the detection modules 110. In a specific embodiment, the frequency of the fundamental wave signal corresponding to each detection module 110 is set to increase sequentially in a preset step. This preset step can be set as needed. For example, the frequency difference between the fundamental wave signals corresponding to two adjacent detection modules 110 can be set to 6 kHz, that is, the frequency of the fundamental wave signal corresponding to each detection module 110 is 6 kHz higher than the frequency of the fundamental wave signal corresponding to the detection module 110 located above it in the direction of gravity. As shown in Figure 2, the frequencies of the fundamental wave signals of each detection module 110, from top to bottom, can be: F1 kHz, (F1+6) kHz…(F1+24) kHz. In one specific embodiment, the fundamental wave signal frequencies corresponding to each detection module 110 are set to decrease sequentially in a preset step. This preset step can be set as needed; for example, the fundamental wave signal frequency interval corresponding to each detection module 110 can be set to 6 kHz, that is, the frequency of the fundamental wave signal corresponding to two adjacent detection modules 110 is 6 kHz lower than the frequency of the fundamental wave signal corresponding to the detection module 110 located above it in the direction of gravity. Those skilled in the art can select and adjust the frequencies of the fundamental wave signals corresponding to each detection module 110 according to actual needs.

[0049] As shown in Figure 2, in one embodiment, the detection modules 110 are arranged along the direction of gravity. For each detection module 110, the harmonic receiving unit 112 may include a first receiving unit 1121. The first receiving unit 1121 is located between two fundamental wave transmitting units 111 that are adjacent along the direction of gravity. The first receiving unit 1121 is used to receive the harmonic signal corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit 111 of the detection module 110 to which it belongs, and to receive the harmonic signal corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit 111 of the detection module 110 adjacent to it. The two fundamental wave transmitting units 111 that are adjacent along the direction of gravity belong to two detection modules 110 that are adjacent along the direction of gravity.

[0050] For example, as shown in Figure 2, one fundamental wave transmitting unit 111 and the first receiving unit 1121 belong to the same detection module 110, such as detection module 110A. Another fundamental wave transmitting unit 111 belongs to a detection module 110 adjacent to the first receiving unit 1121, such as detection module 110B. Detection modules 110A and 110B are arranged sequentially and adjacently in the direction of gravity. Detection module 110A is located above in the direction of gravity. The first receiving unit 1121 in detection module 110A is located between the fundamental wave transmitting unit 111 in detection module 110A and the fundamental wave transmitting unit 111 in detection module 110B, and can receive the harmonic signals corresponding to the fundamental wave signals emitted by these two fundamental wave transmitting units 111, reducing the area of ​​the detection blind zone and thus reducing the false alarm rate of the detection device.

[0051] In this embodiment, placing the first receiving unit 1121 between two adjacent fundamental wave transmitting units 111 can reduce the blind zone range along the direction of gravity between the two detection modules 110. For example, as shown in Figures 1 and 2, if the object being tested is located between the two detection modules 110A and 110B in the security check channel, and the object being tested is far from the fundamental wave transmitting unit 111 of detection module 110A and the harmonic receiving unit 112 of detection module 110B, but close to the harmonic receiving unit 112 of detection module 110A and the fundamental wave transmitting unit 111 of detection module 110B. At this point, if, according to relevant technology, each harmonic receiving unit only receives the harmonic signal from its own detection module 110, then because the object under test is far from the fundamental wave transmitting unit 111 of detection module 110A, the fundamental wave signal reaches the object with low intensity, and the intensity of the harmonic signal generated by the object is correspondingly low. Although the object under test is close to the harmonic receiving unit 112 of detection module 110A, due to the low intensity of the harmonic signal, the harmonic receiving unit 112 has a high probability of not being able to detect the object. Furthermore, although the object under test is close to the fundamental wave transmitting unit 111 of detection module 110B, because the distance between the object under test and the harmonic receiving unit 112 of detection module 110B is far, the probability of the object being detected by the harmonic receiving unit 112 of detection module 110B is also low. In summary, the probability of the object being detected is low at this time, meaning that the location of the object under test is a blind zone. However, this embodiment overcomes this problem. Since the harmonic receiving unit 112 can receive harmonic signals from adjacent detection modules 110 in addition to its own detection module 110, for example, the harmonic receiving unit 112 of detection module 110A can receive harmonic signals from both detection modules 110A and 110B. If the object under test is located in the area between these two detection modules 110 within the detection channel, the harmonic signal radiated by the fundamental wave transmitting unit 111 of detection module 110B, which is closer to the fundamental wave transmitting unit 111, is easily detected by the harmonic receiving unit 112 of detection module 110A. Therefore, by optimizing the receiving scheme of the harmonic receiving unit 112, this solution can effectively reduce the range of the gravity direction blind zone.

[0052] On the other hand, since the door panel is relatively high in the direction of gravity, it is at least greater than the height of a pedestrian. If the first receiving unit 1121 receives a harmonic signal corresponding to the fundamental wave signal emitted by a detection module 110 that is far away (for example, the first receiving unit 1121 is located on the side of the door panel near the top, and another detection module 110 is located on the side of the door panel near the bottom), then at a greater distance, the received signal may be weak or not received at all, which may affect the detection accuracy. Therefore, for the first receiving unit 1121, the distance between it and the adjacent detection module 110 is relatively close. This makes it easier to receive the harmonic signal corresponding to the fundamental wave signal emitted by the adjacent detection module 110, and avoids the aforementioned situation.

[0053] Furthermore, based on an embodiment of the present invention, as shown in FIG2, there are multiple detection modules 110, arranged from top to bottom along the direction of gravity. The multiple detection modules 110 are sequentially defined as the i-th group, where i is greater than or equal to 1. The first receiving unit 1121 in the i-th group simultaneously receives the harmonic signal corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit 111 in the i-th group, and the harmonic signal corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit 111 in the (i+1)-th group. Simply put, in addition to receiving the harmonic signals corresponding to the fundamental wave signal emitted by the detection module 110 (detection module 110A shown in Figure 2), the first receiving unit 1121 can also receive the harmonic signals corresponding to the fundamental wave signal emitted by an adjacent detection module 110 (detection module 110B shown in Figure 2) located below in the direction of gravity. This is equivalent to widening the coverage area of ​​the detection area of ​​the first receiving unit 1121 along the direction of gravity, thereby enabling the detection of the interval area corresponding to the two adjacent detection modules 110 in the detection channel, which reduces the range of the detection blind zone.

[0054] Therefore, by combining the advantages of the two aspects mentioned above, the area between adjacent detection modules 110 can also be covered, thereby reducing the range of the detection blind zone that appears in the gravity direction of the door panel body 100 and reducing the false alarm rate.

[0055] In one specific embodiment, as shown in Figures 2 and 4, the first receiving unit 1121 and the fundamental wave transmitting unit 111 are arranged sequentially in the direction of gravity, and the first receiving unit 1121 may be located below the fundamental wave transmitting unit 111 in the direction of gravity. In another embodiment, the first receiving unit 1121 may also be located above the fundamental wave transmitting unit 111 in the direction of gravity. It should be noted that the arrangement of the first receiving unit 1121 and the fundamental wave transmitting unit 111 in the direction of gravity mentioned in this embodiment refers to the sequential arrangement of the first receiving unit 1121 and the fundamental wave transmitting unit 111 in the direction of gravity within the same detection module 110.

[0056] Specifically, when the first receiving unit 1121 is located below the fundamental wave transmitting unit 111 in the direction of gravity, the distance between the first receiving unit 1121 and the fundamental wave transmitting unit 111 below it is closer. This allows the first receiving unit 1121 to receive not only the harmonic signals from its own detection module 110, but also more easily the harmonic signals corresponding to the fundamental wave signals emitted by the fundamental wave transmitting unit 111 in the detection module 110 below it. When the first receiving unit 1121 is located above the fundamental wave transmitting unit 111 in the direction of gravity, the distance between the first receiving unit 1121 and the fundamental wave transmitting unit 111 in the detection module 110 above it is shorter. This allows the first receiving unit 1121 to receive not only the harmonic signals from its own detection module 110, but also conveniently the harmonic signals corresponding to the fundamental wave signals emitted by the fundamental wave transmitting unit 111 in the detection module 110 above it.

[0057] For example, as shown in FIG2, two adjacent detection modules 110 arranged from top to bottom in the direction of gravity, namely detection module 110A and detection module 110B, will be used for explanation. Since the first receiving unit 1121 of detection module 110A is located below the fundamental wave transmitting unit 111 in the direction of gravity, it can not only receive the harmonic signal corresponding to detection module 110A, but also more easily receive the harmonic signal corresponding to detection module 110B.

[0058] It should also be noted that the security gates in this technology not only have detection blind spots in the direction of gravity but also in the direction of the person's movement. Specifically, as shown in Figures 5 to 7, when the security gate in this technology is working, if the person carrying the object to be tested moves in the direction shown in the figure, only one harmonic receiving unit is set at the same height to receive harmonic signals. When the harmonic receiving unit receives harmonic signals, its signal receiving angle is limited. For nonlinear nodes within this range, the detection sensitivity is high, while for nonlinear nodes outside this range, detection is more difficult (i.e., the area outside this range can be regarded as the detection blind spot in the direction of movement). Therefore, the object to be tested can only be detected if it is exactly within a small area (the fan-shaped area formed by the dashed lines in Figures 5 to 7). At the same time, for areas outside the dashed line range, due to detection sensitivity and other reasons, it may not be detected. Moreover, during the security gate detection process, since the detection channel is generally not very long, the time it takes for the person carrying the item to pass through the detection channel is also short. Consequently, the amount of effective detection data that the harmonic receiving unit can receive during the detection process is also small, making it difficult to accurately identify the object being tested, resulting in a high rate of missed detections and false alarms.

[0059] It should be noted that the aforementioned sector-shaped area is a virtual area defined for ease of explanation. In specific embodiments, the actual boundary of the detection area is not necessarily regular; it is merely idealized into a relatively regular shape for ease of explanation. As shown in Figure 8, in one embodiment of the present invention, the harmonic receiving unit 112 may further include a second receiving unit 1122. The second receiving unit 1122 is located differently from the first receiving unit 1121 in the direction perpendicular to the direction of gravity. The second receiving unit 1122 is used to receive the harmonic signal corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit 111 of the detection module 110 to which it belongs.

[0060] Specifically, in each detection module 110, in addition to the first receiving unit 1121, a second receiving unit 1122 is also provided, thus increasing the number of modules for receiving harmonic signals. Furthermore, the second receiving unit 1122 is positioned differently from the first receiving unit 1121 in the direction of travel; that is, the detection area corresponding to the second receiving unit 1122 and the detection area corresponding to the first receiving unit 1121 do not overlap at least partially in the direction of travel. This increases the coverage of the entire detection area corresponding to the door panel (i.e., including the detection areas corresponding to each detection module 110) in the vertical direction of gravity (the direction of travel in Figures 10-12), reducing the range of the detection blind zone in the direction of travel.

[0061] Meanwhile, the two detection zones formed perpendicular to the direction of gravity extend the path through which the object can be detected, thereby increasing the data acquisition time and the amount of data, improving the accuracy of the detection results, and avoiding inaccurate results and missed detections due to the object's path being too short (small detection area coverage). The entire detection area corresponding to the door panel has a significantly increased coverage in the direction of travel, ensuring that the object can be detected regardless of its position as long as it enters the detection area, reducing the blind spot in the direction of travel and lowering the false alarm rate during detection.

[0062] The second receiving unit 1122 and the first receiving unit 1121 are located in different positions in the direction perpendicular to the direction of gravity. Their positions in the direction of gravity can be the same or different.

[0063] In one specific embodiment, the second receiving unit 1122 and the first receiving unit 1121 are located at different positions in the direction of gravity; that is, the second receiving unit 1122 is located above the first receiving unit 1121 in the direction of gravity, and the other is located below. For example, as shown in FIG9, the first receiving unit 1121 is located below in the direction of gravity, and the second receiving unit 1122 is located above.

[0064] In this configuration, a second receiving unit 1122 is added, which increases the number of modules for receiving harmonic signals in the direction of gravity. Since the second receiving unit 1122 and the first receiving unit 1121 are positioned differently in the direction of gravity, the coverage areas of their respective detection regions also differ in the direction of gravity. Therefore, the coverage area of ​​the detection module 110 in the direction of gravity is increased, thereby reducing the detection blind zone and lowering the false alarm rate.

[0065] The differences between security gates in related technologies and the security gates provided in the embodiments of this application will be described in detail below with reference to Figures 3 and 4.

[0066] As shown in Figure 3, in the security gate of the related technology, multiple detection modules can be arranged at intervals along the direction of gravity. However, since there is only one harmonic receiving unit in the detection module, and the harmonic receiving unit only receives the harmonic signal of the detection module it is in, a detection blind zone will be formed between the detection areas of two adjacent detection modules.

[0067] The solution provided in this embodiment overcomes the above-mentioned problems. As shown in Figure 4, taking detection modules 110A and 110B as examples, along the direction of gravity, if the height of the object being measured is close to the second receiving unit 1122 of detection module 110A, the harmonic signal radiated by the object being measured is more easily received by the second receiving unit 1122 of detection module 110A. If the height of the object being measured is between detection modules 110A and 110B, the fundamental wave signal radiated by the fundamental wave transmitting unit 111 of detection module 110B is relatively strong when it reaches the object being measured. Furthermore, the first receiving unit 1121 in detection module 110A is closer to the object being measured and can also receive the harmonic signal radiated after the fundamental wave signal from detection module 110B reaches the object being measured. Therefore, the harmonic signal is more easily received by the first receiving unit 1121 in detection module 110A. In summary, regardless of the location of the object being measured along the direction of gravity, the harmonic signals radiated by it can be effectively received by each receiving unit, thereby reducing the false alarm rate.

[0068] In summary, for this embodiment, by adding a second receiving unit 1122 and adjusting its position in the gravity direction and the travel direction, the range of the detection blind zone in the gravity direction and the range of the detection blind zone in the travel direction can be reduced respectively, thus having two functions.

[0069] As shown in Figure 9, in one embodiment of the present invention, the harmonic receiving unit 112 may further include a third receiving unit 1123. The third receiving unit 1123 is located at a different position from the first receiving unit 1121 and the second receiving unit 1122 in the direction perpendicular to the direction of gravity. The third receiving unit 1123 is used to receive the harmonic signal corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit 111 in the detection module 110 where it is located.

[0070] Specifically, in each detection module 110, the third receiving unit 1123, the second receiving unit 1122, and the first receiving unit 1121 are positioned differently in the vertical direction of gravity. For example, the second receiving unit 1122 may be located to the left of the fundamental wave transmitting unit 111, and the third receiving unit 1123 may be located to the right of the fundamental wave transmitting unit 111. In some embodiments, the second receiving unit 1122 and the third receiving unit 1123 may be located simultaneously to the left or right of the fundamental wave transmitting unit 111, and the first receiving unit 1121 may be located between the second receiving unit 1122 and the third receiving unit 1123. Simply put, the first receiving unit 1121, the second receiving unit 1122, and the third receiving unit 1123 can be arranged in a vertical direction along the direction of gravity. The first receiving unit 1121, the second receiving unit 1122, and the third receiving unit 1123 will each form different detection areas in the vertical direction of gravity, and the person carrying the device will pass through these detection areas sequentially during travel. If the first receiving unit 1121, the second receiving unit 1122, and the third receiving unit 1123 are offset in the direction perpendicular to the direction of gravity, the corresponding three detection areas will also be partially offset. This will allow the three detection areas to collectively form a larger detection area, thereby increasing the coverage of the detection module 110 in the direction perpendicular to the direction of gravity and reducing the detection blind zone. Furthermore, based on this embodiment, compared to the current solution, adding a third receiving unit 1123 in the direction of travel and adjusting the positions of the third receiving unit 1123 relative to the first receiving unit 1121 and the second receiving unit 1122 in the direction of travel can also increase the coverage of the detection area, reduce the detection blind zone, and increase the amount of acquired detection data. The specific principle is the same as that of the embodiment with the second receiving unit 1122 added, and will not be elaborated further here.

[0071] It should be noted that the difference in the positions of the third receiving unit 1123, the second receiving unit 1122, and the first receiving unit 1121 in the vertical direction of gravity refers only to the difference in the positions of their projections in the vertical direction of gravity. Whether the positions of the three receiving units in the direction of gravity are the same is within the scope of protection of this application. For example, the position of the third receiving unit 1123 in the direction of gravity may be the same as or different from that of the first receiving unit 1121.

[0072] In one specific embodiment, the third receiving unit 1123 and the first receiving unit 1121 are located at different positions in the direction of gravity; that is, the third receiving unit 1123 is located above the first receiving unit 1121 in the direction of gravity, and the other is located below. For example, as shown in FIG9, the first receiving unit 1121 is located below in the direction of gravity, and the third receiving unit 1123 is located above.

[0073] In this configuration, by adding a third receiving unit 1123, the number of modules for receiving signals in the direction of gravity is increased. Since the third receiving unit 1123 and the first receiving unit 1121 are positioned differently in the direction of gravity, their corresponding detection areas also have different coverage areas in the direction of gravity. Therefore, the detection range of the detection module 110 in the direction of gravity is increased, thereby reducing the detection blind zone in the direction of gravity and lowering the false alarm rate.

[0074] In summary, for this embodiment, the addition of a third receiving unit 1123 and the adjustment of its position in the gravity direction and the travel direction can reduce the range of the detection blind zone in the gravity direction and the range of the detection blind zone in the travel direction, respectively, thus having two functions.

[0075] It should be noted that in other embodiments, at least two of the first receiving unit 1121, the second receiving unit 1122, and the third receiving unit 1123 are positioned differently in the direction of gravity. The specific principles and advantages are the same as in the embodiments described above, and will not be elaborated upon here. For example, as shown in FIG9, the first receiving unit 1121, the third receiving unit 1123, and the second receiving unit 1122 are arranged sequentially from bottom to top in the direction of gravity.

[0076] In one embodiment, as shown in FIG10, in each detection module 110, the second receiving unit 1122 and the third receiving unit 1123 can be respectively arranged on both sides of the fundamental wave transmitting unit 111. The detection areas corresponding to the three receiving units are arranged sequentially along the direction of travel to increase the coverage of the detection area of ​​the detection module 110 in the direction perpendicular to the direction of gravity (i.e., the direction of travel in FIG11-FIG13), minimize the range of detection blind spots, and reduce the false alarm rate. In a specific embodiment, the distance between the second receiving unit 1122 and the third receiving unit 1123 and the fundamental wave transmitting unit 111 can be appropriately set to ensure that the detection areas corresponding to the three receiving units cover the entire detection channel in the direction of travel, thereby reducing the range of detection blind spots in the direction of travel.

[0077] In one specific embodiment, when the harmonic receiving unit 112 in the detection module 110 includes a first receiving unit 1121, a second receiving unit 1122, and a third receiving unit 1123, the second receiving unit 1122, the first receiving unit 1121, and the third receiving unit 1123 are arranged sequentially in the travel direction of the detection channel. As shown in Figures 11 to 13, when the person carrying the object to be tested moves in the travel direction, upon entering the detection channel of the security inspection device, the person first enters the detection area corresponding to the second receiving unit 1122, and the detection module 110 can receive the harmonic signal generated by the object to be tested through the second receiving unit 1122. When the person continues to move and reaches the middle position of the detection channel, the harmonic signal can be received through at least one of the first receiving unit 1121, the second receiving unit 1122, and the third receiving unit 1123. When the carrier leaves the detection channel, i.e., moves to the boundary of the detection channel, the detection module 110 can receive harmonic signals through the third receiving unit 1123. This process ensures that the object under test can be detected throughout the entire detection channel. That is, as long as the carrier enters the detection channel, regardless of where the object is placed on the carrier, the resulting harmonic signals will not be blocked or weakened by the carrier and can be received by any receiving unit, completing the detection work. Compared with related technologies, this embodiment expands the coverage area of ​​the detection region and reduces the detection blind zone of the entire detection channel in the direction of travel (the direction perpendicular to the aforementioned direction of gravity). Furthermore, by setting the second receiving unit 1122 and the third receiving unit 1123 on both sides of the first receiving unit 1121, not only is the detection distance extended, but the detection time is also extended. The amount of data that the detection module 110 can receive increases exponentially, improving detection accuracy and reducing the false negative rate during the detection process.

[0078] In some embodiments of this application, as shown in FIG10, the first receiving unit 1121 of the detection module 110 located at the top in the direction of gravity can not only receive the second and third harmonic signals (2F1, 3F1) corresponding to the fundamental wave signal (F1) emitted by the fundamental wave transmitting unit 111 in the detection module 110 where it is located, but also receive the second and third harmonic signals (2F2, 3F2) corresponding to the fundamental wave signal (F2) emitted by the fundamental wave transmitting unit 111 in the detection module 110 located below the first receiving unit 1121. Meanwhile, the fundamental wave signals emitted by the fundamental wave transmitting unit 111 in each detection module 110 have different frequencies. When the first receiving unit 1121 receives the second and third harmonic signals from two different detection modules 110 at the same time, it can identify the detection module 110 corresponding to the harmonic signal based on the frequency of the harmonic signal. That is, it can determine which fundamental wave signal in the detection module 110 the harmonic signal corresponds to. This can speed up the detection process by obtaining the detection result based on the harmonic signal. In addition to increasing the detection area of ​​the detection module 110 and reducing the blind zone, it can also improve the processing speed of the detection module 110 during the detection process, ensure the timeliness and accuracy of the detection results, and reduce the false alarm rate.

[0079] Meanwhile, in a detection module 110, the second receiving unit 1122 and the third receiving unit 1123 can receive the second and third harmonic signals generated corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit 111 in their respective detection modules 110. For example, in Figure 10, in the detection module 110 located at the top in the direction of gravity, the second receiving unit 1122 and the third receiving unit 1123 can receive the second and third harmonic signals (2F1, 3F1) generated corresponding to the fundamental wave signal (F1) emitted by the fundamental wave transmitting unit 111. In the second detection module 110 from the top, the second receiving unit 1122 and the third receiving unit 1123 can receive the second and third harmonic signals (2F2, 3F2) generated corresponding to the fundamental wave signal (F2) emitted by the fundamental wave transmitting unit 111 in their respective detection modules 110. And so on. The remaining detection modules 110 will not be described in detail here, as the principle is the same. By additionally setting a second receiving unit 1122 and a third receiving unit 1123 in the direction perpendicular to the direction of gravity, the coverage of the detection area of ​​the detection module 110 in the direction perpendicular to the direction of gravity is expanded, and the range of the detection blind zone is reduced.

[0080] In one embodiment, when the first receiving unit 1121 has only one adjacent fundamental wave transmitting unit 111, the first receiving unit 1121 can be configured to receive only the harmonic signals corresponding to the fundamental wave signals emitted by the fundamental wave transmitting unit 111. For example, as shown in FIG10, for the detection module 110 located at the bottom in the direction of gravity, since there is no detection module 110 below it, the first receiving unit 1121 can be used only to receive the harmonic signals corresponding to the fundamental wave signals emitted by the fundamental wave transmitting unit 111 in the detection module 110 to which it is located.

[0081] This invention also provides a security inspection device, including at least one of the aforementioned door panels. In one embodiment, the door panel forms a detection channel for detecting objects passing through it. The security inspection device may further include a main control module, with the detection modules 110 in the door panel connected to the main control module. The main control module obtains a final judgment result for the object being inspected based on the detection results of each detection module 110.

[0082] In one specific embodiment, a single door panel can form a detection channel with the surface of other devices, such as walls or other plate-like objects. For example, a security inspection device may include the aforementioned door panel and a plate-like member that only provides a supporting structure and does not have a detection function; its role is solely to cooperate with the door panel to form a detection channel for people to pass through.

[0083] In another embodiment, the security inspection device may include two of the above-mentioned door panels and a main control module. The two door panels are spaced apart to form a detection channel for detecting human bodies or objects passing through the detection channel. The detection module 110 in each door panel is connected to the main control module of the security inspection device. The main control module obtains the judgment result of the object to be tested based on the detection results of each detection module 110.

[0084] In one specific embodiment, as shown in Figure 4, the security inspection device is a security gate comprising two of the aforementioned door panels. The two door panels and the top panel together form a detection channel. During the process of a pedestrian carrying an object to be tested passing through the detection channel, the object can be detected by the detection module 110 in each door panel. When the object to be tested contains nonlinear nodes, harmonic signals will be generated under the influence of the fundamental wave signal emitted by the detection module 110. The detection module 110 can receive the harmonic signals and perform operations such as identification and alarm. Alternatively, the detection module 110 can also process the received harmonic signals and send them to other devices (such as a main control module), which can then perform operations such as identification and alarm on the processed signals.

[0085] In this application embodiment, the security inspection device uses the aforementioned door panel. In the aforementioned door panel, the harmonic receiving unit 112 in the detection module 110 can receive the harmonic signals generated corresponding to the fundamental wave signals emitted by the fundamental wave transmitting unit 111 in its own detection module 110 and at least one other detection module 110. The detection area coverage of the harmonic receiving unit 112 will be larger. Compared with related technologies, it can reduce the range of the detection blind zone. The object being tested can also be detected when it is in the interval area between two adjacent detection modules 110, thereby reducing the false alarm rate of the security inspection device.

[0086] It should be noted that the operation process of each gate panel can be referred to the description above. The two gate panels can be set to be controlled by the same main control module, or they can be set to be controlled by different main control modules. In some application scenarios, such as airports and subways, this security gate can be used to minimize missed or false alarms, ensuring the security of various locations.

[0087] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0088] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A door panel, comprising: The door panel body and at least two detection modules on the door panel body; The detection module includes: a fundamental wave transmitting unit for transmitting fundamental wave signals and a harmonic receiving unit for receiving harmonic signals; At least one of the harmonic receiving units of the detection module is used to receive the harmonic signal corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit in the detection module, and to receive the harmonic signal corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit in at least one other detection module.

2. The door panel according to claim 1, characterized in that, The fundamental wave signals emitted by the fundamental wave transmitting units of at least two detection modules have different frequencies, and the harmonic signals corresponding to the fundamental wave signals with at least two different frequencies are received by the same harmonic receiving unit.

3. The door panel according to claim 1, characterized in that, The number of the detection modules is multiple, and they are arranged along the direction of gravity; The fundamental wave signals emitted by the fundamental wave transmitting units of any two adjacent detection modules have different frequencies.

4. The door panel according to claim 3, characterized in that, The frequencies of the fundamental wave signals emitted by the fundamental wave transmitting units of all the aforementioned detection modules decrease or increase sequentially along the direction of gravity.

5. The door panel according to claim 1, characterized in that, Each of the aforementioned detection modules is arranged along the direction of gravity; the harmonic receiving unit includes a first receiving unit, which is located between two adjacent fundamental wave transmitting units along the direction of gravity. The first receiving unit is used to receive the harmonic signal corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit of the detection module to which it is located, and to receive the harmonic signal corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit of the detection module adjacent to it.

6. The door panel according to claim 5, characterized in that, The number of the detection modules is multiple, and they are arranged from top to bottom along the direction of gravity. The multiple detection modules are sequentially defined as the i-th group, where i is greater than or equal to 1. The first receiving unit in the i-th group simultaneously receives the harmonic signal corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit in the i-th group, as well as the harmonic signal corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit in the (i+1)-th group.

7. The door panel according to claim 5, characterized in that, In the same detection module, the first receiving unit is located below the fundamental wave transmitting unit in the direction of gravity.

8. The door panel according to claim 5, characterized in that, The harmonic receiving unit further includes a second receiving unit, which is located differently from the first receiving unit in the direction perpendicular to the direction of gravity. The second receiving unit is used to receive the harmonic signal corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit of the detection module to which it is located.

9. The door panel according to claim 8, characterized in that, The second receiving unit is located on one side of the fundamental wave transmitting unit in the direction perpendicular to the direction of gravity.

10. The door panel according to claim 8, characterized in that, The harmonic receiving unit further includes a third receiving unit, which is located at a different position from the first receiving unit in the direction perpendicular to the direction of gravity. The third receiving unit is used to receive the harmonic signal corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit in the detection module in which it is located.

11. The door panel according to claim 10, characterized in that, The second receiving unit and the third receiving unit are located on opposite sides of the fundamental wave transmitting unit.

12. The door panel according to claim 1, characterized in that, The fundamental wave signals emitted by all the aforementioned detection modules have different frequencies.

13. The door panel according to claim 8, characterized in that, The second receiving unit is located in a different position from the first receiving unit in the direction of gravity.

14. The door panel according to claim 10, characterized in that, The third receiving unit is located in a different position from the first receiving unit and the second receiving unit in the direction perpendicular to the direction of gravity.

15. The door panel according to claim 10, characterized in that, The third receiving unit is located in a different position from the first receiving unit in the direction of gravity.

16. The door panel according to claim 10, characterized in that, At least two of the first receiving unit, the second receiving unit, and the third receiving unit are located at different positions in the direction of gravity.

17. A door panel, comprising: The door panel body and at least two detection modules on the door panel body; The detection module includes: a fundamental wave transmitting unit for transmitting fundamental wave signals and a harmonic receiving unit for receiving harmonic signals; Each of the detection modules is arranged along the direction of gravity; the harmonic receiving unit includes a first receiving unit, which is located between two fundamental wave transmitting units that are adjacent along the direction of gravity.

18. The door panel according to claim 17, characterized in that, In the same detection module, the first receiving unit is located below the fundamental wave transmitting unit in the direction of gravity.

19. The door panel according to claim 17, characterized in that, The harmonic receiving unit further includes a second receiving unit, which is located differently from the first receiving unit in the direction perpendicular to the direction of gravity.

20. A security inspection device, comprising a door panel; the door panel comprising: The door panel body and at least two detection modules on the door panel body; The detection module includes: a fundamental wave transmitting unit for transmitting fundamental wave signals and a harmonic receiving unit for receiving harmonic signals; At least one of the harmonic receiving units of the detection module is used to receive the harmonic signal corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit in the detection module, and to receive the harmonic signal corresponding to the fundamental wave signal emitted by the fundamental wave transmitting unit in at least one other detection module.

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