Security check door and metal detection method and device for security check door

Abstract

The invention relates to a security check door and a metal detection method and device for the security check door. Based on the security check door, the security check door comprises two sets of coil assemblies, and the two sets of coil assemblies are configured to alternately work in a time-sharing manner, so that a primary magnetic field in a detection channel is a single-side primary magnetic field generated by a transmitting coil in one set of coil assembly; the receiving coil in each set of coil assembly is located in an attenuation area after the single-side primary magnetic field is attenuated across the detection channel during working, so that the primary magnetic field intensity sensed by the receiving coil during working can be reduced. Therefore, if the target metal exists in the detection channel, even if the target metal is a small metal object with a small size, the secondary magnetic field generated by the target metal possibly penetrates through the attenuation area of the single-side primary magnetic field and is successfully induced by the receiving coil, and the omission ratio of the security door is further reduced.

Description

Technical Field

[0001] The present application relates to security inspection equipment, and in particular to a security inspection door, a metal detection method for the security inspection door, and a target metal detection device for the security inspection door. Background Art

[0002] The door panels on both sides of the security door are equipped with transmitting coils and receiving coils. The magnetic signals generated by the transmitting coils installed on the door panels on both sides can form a primary magnetic field in the detection channel between the door panels on both sides. During this period, if the object to be detected passing through the detection channel carries metal objects, the metal objects can generate a secondary magnetic field under the action of the primary magnetic field, and the superposition of the secondary magnetic field and the primary magnetic field will cause the signal strength of the receiving signal generated by the receiving coil to fluctuate. Therefore, by identifying the signal strength of the receiving signal generated by the receiving coil, it can be detected whether the current object to be detected carries metal objects.

[0003] Among them, the intensity of the secondary magnetic field is smaller than the magnetic field intensity of the primary magnetic field, and the intensity of the secondary magnetic field is also related to the volume of the metal object, that is, under the action of the primary magnetic field of the same intensity, the smaller the volume of the metal object, the smaller the intensity of the secondary magnetic field generated.

[0004] For small metal objects such as paper clips, metal coins, screws, etc., the strength of the secondary magnetic field generated by the primary magnetic field will be much smaller than the strength of the primary magnetic field. In this case, the secondary magnetic field surrounded by the primary magnetic field is difficult to be successfully sensed by the receiving coil, resulting in missed detection of small metal objects.

[0005] That is, the security gate's ability to detect metal objects is only effective for metal objects of larger size, which results in a high rate of missed detection of small metal objects by the security gate.

[0006] It can be seen that how to reduce the missed detection rate of security doors has become a technical problem to be solved in the prior art. Summary of the invention

[0007] In an embodiment of the present application, a security door, a metal detection method for a security door, and a target metal detection device for a security door are provided, which help to reduce the missed detection rate of the security door.

[0008] An embodiment of the present application provides a security door comprising:

[0009] The door panel assembly comprises a first door panel and a second door panel respectively arranged on opposite sides of the detection channel in the width direction;

[0010] an induction component, comprising a first coil component and a second coil component, wherein the first coil component comprises a first receiving coil arranged on the first door panel and a first transmitting coil arranged on the second door panel, and the second coil component comprises a second receiving coil arranged on the second door panel and a second transmitting coil arranged on the first door panel;

[0011] A control component is used to control the first coil component and the second coil component to work in a first time slot and a second time slot of an alternating cycle respectively, and is also used to:

[0012] Obtain a first discrete receiving signal obtained by the first receiving coil inducing the physical magnetic field in the detection channel in the first time slot, and a second discrete receiving signal obtained by the second receiving coil inducing the physical magnetic field in the second time slot, wherein the signal strength of the first discrete receiving signal is used to characterize the first unilateral magnetic field strength of the physical magnetic field on the side where the first door panel is located, and the signal strength of the second discrete receiving signal is used to characterize the second unilateral magnetic field strength of the physical magnetic field on the side where the second door panel is located, and the physical magnetic field includes the unilateral primary magnetic field alternately generated by the first transmitting coil and the second transmitting coil in the first time slot and the second time slot respectively;

[0013] Based on the first discrete received signal and the second discrete received signal, detecting intensity fluctuations of the first unilateral magnetic field intensity and the second unilateral magnetic field intensity;

[0014] In response to the detection result that the fluctuation amplitude of the intensity fluctuation reaches the target amplitude, it is determined that the target metal exists in the detection channel, wherein the target amplitude is used to characterize the magnetic field intensity threshold of the secondary magnetic field generated by the target metal based on the unilateral primary magnetic field.

[0015] In some examples, optionally, the control component is specifically configured to: detect the intensity fluctuation of the first unilateral magnetic field strength and the second unilateral magnetic field strength compared to the primary magnetic field strength of the unilateral primary magnetic field based on the first discrete received signal and the second discrete received signal, wherein the primary magnetic field strength is associated with the signal strength of the transmission signal alternately generated by the first transmitting coil and the second transmitting coil.

[0016] In some examples, optionally, the control component is specifically configured to: utilize the signal strength of the transmitted signal to perform signal demodulation on the first discrete received signal and the second discrete received signal with the unilateral primary magnetic field as the carrier; and detect the intensity changes of the first unilateral magnetic field strength and the second unilateral magnetic field strength based on the demodulation result of the signal demodulation; wherein the demodulation result includes first discrete amplitude information obtained by performing the signal demodulation on the first discrete received signal, and second discrete amplitude information obtained by performing the signal demodulation on the second discrete received signal, the first discrete amplitude information being used to characterize the first fluctuation amplitude of the first unilateral magnetic field strength compared to the primary magnetic field strength, the second discrete amplitude information being used to characterize the second fluctuation amplitude of the second unilateral magnetic field strength compared to the primary magnetic field strength, and the detection result of the intensity fluctuation reaching the target amplitude includes at least one of the first fluctuation amplitude and the second fluctuation amplitude reaching the target amplitude.

[0017] In some examples, optionally, the control component is specifically configured to: perform discrete numerical value continuation processing on the first discrete amplitude information and the second discrete amplitude information; determine whether the first change amplitude and the second change amplitude reach the target amplitude by comparing the processing result of the discrete numerical value continuation processing with the target amplitude; wherein the processing result of the discrete numerical value continuation processing includes: a first continuous amplitude sequence obtained by performing the discrete numerical value continuation processing on the first discrete amplitude information, and a second continuous amplitude sequence obtained by performing the discrete numerical value continuation processing on the second discrete amplitude information.

[0018] In some examples, optionally, the control component is specifically configured to: successively perform interpolation processing and smoothing filtering on the first discrete amplitude information to obtain the first continuous amplitude sequence; successively perform interpolation processing and smoothing filtering on the second discrete amplitude information to obtain the second continuous amplitude sequence; wherein the interpolation processing of the first discrete amplitude information and the second discrete amplitude information includes: determining the amplitude value at the end time of the previous valid time slot of each invalid time slot where information is missing as the amplitude value of the invalid time slot.

[0019] In some examples, optionally, the control component is further used to: generate an alarm signal in response to a detection event of the target metal in the detection channel, wherein the alarm signal is used to indicate that the object to be detected currently passing through the detection channel carries the target metal.

[0020] In some examples, optionally, it also includes a first transmitting circuit connected between the control component and the first transmitting coil, a second transmitting circuit connected between the control component and the second transmitting coil, a first receiving circuit connected between the control component and the first receiving coil, and a second receiving circuit connected between the control component and the second receiving coil, the first transmitting circuit and the second transmitting circuit both include a full-bridge inverter circuit, and the control component is specifically configured to: activate the first transmitting circuit and the first receiving circuit in the first time slot, turn off the second transmitting circuit and the second receiving circuit, and activate the second transmitting circuit and the second receiving circuit in the second time slot, and turn off the first transmitting circuit and the first receiving circuit.

[0021] In some examples, optionally, a third transmitting circuit and a third receiving circuit connected to the control component are further included, the third transmitting circuit is connected to the first transmitting coil and the second transmitting coil through a first two-to-one switch, the third transmitting circuit includes a full-bridge inverter circuit, and the third receiving circuit is connected to the first receiving coil and the second receiving coil through a second two-to-one switch, and the control component is specifically configured to control the first two-to-one switch and the second two-to-one switch so that: the third transmitting circuit is connected to the first transmitting coil in the first time slot and is connected to the second transmitting coil in the second time slot, and the third receiving circuit is connected to the first receiving coil in the first time slot and is connected to the second receiving coil in the second time slot.

[0022] Another embodiment of the present application provides a metal detection method for a security door, the security door comprising a door panel assembly and a sensing assembly, the door panel assembly comprising a first door panel and a second door panel respectively arranged on opposite sides of a detection channel in a width direction, the sensing assembly comprising a first coil assembly and a second coil assembly, the first coil assembly comprising a first receiving coil arranged on the first door panel, and a first transmitting coil arranged on the second door panel, and the second coil assembly comprising a second receiving coil arranged on the second door panel, and a second transmitting coil arranged on the first door panel, the metal detection method controls the first coil assembly and the second coil assembly to work in a first time slot and a second time slot of an alternating cycle, respectively, and the metal detection method comprises:

[0023] Obtain a first discrete receiving signal obtained by the first receiving coil inducing the physical magnetic field in the detection channel in the first time slot, and a second discrete receiving signal obtained by the second receiving coil inducing the physical magnetic field in the second time slot, wherein the signal strength of the first discrete receiving signal is used to characterize the first unilateral magnetic field strength of the physical magnetic field on the side where the first door panel is located, and the signal strength of the second discrete receiving signal is used to characterize the second unilateral magnetic field strength of the physical magnetic field on the side where the second door panel is located, and the physical magnetic field includes the unilateral primary magnetic field alternately generated by the first transmitting coil and the second transmitting coil in the first time slot and the second time slot respectively;

[0024] Based on the first discrete received signal and the second discrete received signal, detecting intensity fluctuations of the first unilateral magnetic field strength and the second unilateral magnetic field strength, wherein the primary magnetic field strength is used to characterize the calibrated magnetic field strength of the unilateral primary magnetic field;

[0025] In response to the detection result that the fluctuation amplitude of the intensity fluctuation reaches the target amplitude, it is determined that the target metal exists in the detection channel, wherein the target amplitude is used to characterize the magnetic field intensity threshold of the secondary magnetic field generated by the target metal based on the unilateral primary magnetic field.

[0026] In some examples, optionally, detecting the intensity fluctuation of the first unilateral magnetic field strength and the second unilateral magnetic field strength based on the first discrete received signal and the second discrete received signal includes: detecting the intensity fluctuation of the first unilateral magnetic field strength and the second unilateral magnetic field strength compared to the primary magnetic field strength of the unilateral primary magnetic field based on the first discrete received signal and the second discrete received signal, wherein the primary magnetic field strength is associated with the signal strength of the transmitting signal alternately generated by the first transmitting coil and the second transmitting coil.

[0027] In some examples, optionally, the detecting, based on the first discrete received signal and the second discrete received signal, the intensity fluctuation of the first unilateral magnetic field strength and the second unilateral magnetic field strength compared to the primary magnetic field strength includes: using the signal strength of the transmitted signal to perform signal demodulation on the first discrete received signal and the second discrete received signal using the unilateral primary magnetic field as a carrier; based on the demodulation result of the signal demodulation, detecting the intensity change of the first unilateral magnetic field strength and the second unilateral magnetic field strength; wherein the demodulation result includes first discrete amplitude information obtained by performing the signal demodulation on the first discrete received signal, and second discrete amplitude information obtained by performing the signal demodulation on the second discrete received signal, the first discrete amplitude information being used to characterize the first fluctuation amplitude of the first unilateral magnetic field strength compared to the primary magnetic field strength, the second discrete amplitude information being used to characterize the second fluctuation amplitude of the second unilateral magnetic field strength compared to the primary magnetic field strength, and the detection result that the intensity fluctuation reaches the target amplitude includes at least one of the first fluctuation amplitude and the second fluctuation amplitude reaching the target amplitude.

[0028] In some examples, optionally, the demodulation result based on the signal demodulation is used to detect the intensity change of the first unilateral magnetic field strength and the second unilateral magnetic field strength, including: performing discrete numerical value continuity processing on the first discrete amplitude information and the second discrete amplitude information; comparing the processing result of the discrete numerical value continuity processing with the target amplitude to determine whether the first change amplitude and the second change amplitude reach the target amplitude; wherein the processing result of the discrete numerical value continuity processing includes: a first continuous amplitude sequence obtained by performing the discrete numerical value continuity processing on the first discrete amplitude information, and a second continuous amplitude sequence obtained by performing the discrete numerical value continuity processing on the second discrete amplitude information.

[0029] In some examples, optionally, the discrete numerical continuity processing of the first discrete amplitude information and the second discrete amplitude information includes: successively performing interpolation processing and smoothing filtering on the first discrete amplitude information to obtain the first continuous amplitude sequence; successively performing interpolation processing and smoothing filtering on the second discrete amplitude information to obtain the second continuous amplitude sequence; wherein the interpolation processing of the first discrete amplitude information and the second discrete amplitude information includes: determining the amplitude value at the end time of the previous valid time slot of each invalid time slot where information is missing as the amplitude value of the invalid time slot.

[0030] In some examples, optionally, it further includes: generating an alarm signal in response to a detection event of the target metal in the detection channel, wherein the alarm signal is used to indicate that the object to be detected currently passing through the detection channel carries the target metal.

[0031] Another embodiment of the present application provides a metal detection device for a security door, the security door comprising a door panel assembly, a first coil assembly and a second coil assembly, the door panel assembly comprising a first door panel and a second door panel respectively arranged on opposite sides of a detection channel in a width direction, the first coil assembly comprising a first receiving coil arranged on the first door panel, and a first transmitting coil arranged on the second door panel, the second coil assembly comprising a second receiving coil arranged on the second door panel, and a second transmitting coil arranged on the first door panel, the first coil assembly and the second coil assembly working alternately at a preset frequency in time division, and the target metal detection device comprising:

[0032] a signal acquisition module, used for acquiring a first discrete receiving signal obtained by the first receiving coil inducing the physical magnetic field in the detection channel in the first time slot, and a second discrete receiving signal obtained by the second receiving coil inducing the physical magnetic field in the second time slot, wherein the signal strength of the first discrete receiving signal is used to characterize the first unilateral magnetic field strength of the physical magnetic field on the side where the first door panel is located, and the signal strength of the second discrete receiving signal is used to characterize the second unilateral magnetic field strength of the physical magnetic field on the side where the second door panel is located, and the physical magnetic field includes the unilateral primary magnetic field alternately generated by the first transmitting coil and the second transmitting coil in the first time slot and the second time slot respectively;

[0033] an intensity detection module, configured to detect intensity fluctuations of the first unilateral magnetic field intensity and the second unilateral magnetic field intensity based on the first discrete received signal and the second discrete received signal, wherein the primary magnetic field intensity is used to characterize a calibrated magnetic field intensity of the unilateral primary magnetic field;

[0034] A target identification module is used to determine the presence of target metal in the detection channel in response to a detection result that the fluctuation amplitude of the intensity fluctuation reaches a target amplitude, wherein the target amplitude is used to characterize the magnetic field intensity threshold of the secondary magnetic field generated by the target metal based on the unilateral primary magnetic field.

[0035] In some examples, optionally, the strength detection module is specifically used to: detect the intensity fluctuation of the first unilateral magnetic field strength and the second unilateral magnetic field strength compared to the primary magnetic field strength of the unilateral primary magnetic field based on the first discrete received signal and the second discrete received signal, wherein the primary magnetic field strength is associated with the signal strength of the transmitting signal alternately generated by the first transmitting coil and the second transmitting coil.

[0036] In some examples, optionally, the strength detection module is specifically used to: utilize the signal strength of the transmitted signal to perform signal demodulation on the first discrete received signal and the second discrete received signal with the unilateral primary magnetic field as the carrier; and detect the intensity changes of the first unilateral magnetic field strength and the second unilateral magnetic field strength based on the demodulation result of the signal demodulation; wherein the demodulation result includes first discrete amplitude information obtained by performing the signal demodulation on the first discrete received signal, and second discrete amplitude information obtained by performing the signal demodulation on the second discrete received signal, the first discrete amplitude information being used to characterize the first fluctuation amplitude of the first unilateral magnetic field strength compared to the primary magnetic field strength, the second discrete amplitude information being used to characterize the second fluctuation amplitude of the second unilateral magnetic field strength compared to the primary magnetic field strength, and the detection result of the intensity fluctuation reaching the target amplitude includes at least one of the first fluctuation amplitude and the second fluctuation amplitude reaching the target amplitude.

[0037] In some examples, optionally, the intensity detection module is specifically used to: perform discrete numerical value continuity processing on the first discrete amplitude information and the second discrete amplitude information; compare the processing result of the discrete numerical value continuity processing with the target amplitude to determine whether the first change amplitude and the second change amplitude reach the target amplitude; wherein the processing result of the discrete numerical value continuity processing includes: a first continuous amplitude sequence obtained by performing the discrete numerical value continuity processing on the first discrete amplitude information, and a second continuous amplitude sequence obtained by performing the discrete numerical value continuity processing on the second discrete amplitude information.

[0038] In some examples, optionally, the intensity detection module is specifically used to: successively perform interpolation processing and smoothing filtering on the first discrete amplitude information to obtain the first continuous amplitude sequence; successively perform interpolation processing and smoothing filtering on the second discrete amplitude information to obtain the second continuous amplitude sequence; wherein the interpolation processing of the first discrete amplitude information and the second discrete amplitude information includes: determining the amplitude value at the end time of the previous valid time slot of each invalid time slot where information is missing as the amplitude value of the invalid time slot.

[0039] In some examples, optionally, it also includes: an alarm triggering module, which is used to generate an alarm signal in response to a detection event of the target metal in the detection channel, wherein the alarm signal is used to indicate that the object to be detected currently passing through the detection channel carries the target metal.

[0040] Another embodiment of the present application provides a non-transitory computer-readable storage medium, which stores instructions. When the instructions are executed by a processor, the processor performs the metal detection method as described in the above embodiments.

[0041] Based on the embodiment of the present application, the security inspection door includes two sets of coil assemblies, and the two sets of coil assemblies are configured to work alternately in time-sharing, so that the primary magnetic field in the detection channel is a unilateral primary magnetic field generated by the transmitting coil in one set of coil assemblies, and the receiving coils in each set of coil assemblies are located in the attenuation area after the unilateral primary magnetic field crosses the detection channel during operation, thereby reducing the primary magnetic field intensity sensed by the receiving coil during operation. Therefore, if there is a target metal in the detection channel, even if the target metal is a small metal object with a small volume, the secondary magnetic field generated by it may penetrate the attenuation area of ​​the unilateral primary magnetic field and be successfully sensed by the receiving coil, thereby helping to reduce the missed detection rate of the security inspection door. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The following drawings are only used to illustrate and explain the present application, and do not limit the scope of the present application:

[0043] Figure 1 This is a schematic diagram of an exemplary structure of a security door in one embodiment of the present application;

[0044] Figure 2 For Figure 1 An example diagram of a waveform of a discrete received signal acquired by a security door in the illustrated embodiment;

[0045] Figure 3 For Figure 1 A schematic diagram of a first example of a transceiver circuit structure of a security door in the illustrated embodiment;

[0046] Figure 4 For Figure 1 A second example schematic diagram of the structure of the transceiver circuit of the security door in the illustrated embodiment;

[0047] Figure 5 For Figure 3 and Figure 4 The example shown is a waveform example diagram of a discrete transmission signal generated based on a full-bridge inverter circuit;

[0048] Figure 6 For Figure 1A signal-to-noise ratio curve diagram of a first discrete received signal in the illustrated embodiment;

[0049] Figure 7 For Figure 1 A signal-to-noise ratio curve diagram of a second discrete received signal in the illustrated embodiment;

[0050] Figure 8 For Figure 1 A high signal-to-noise ratio curve diagram based on bilateral unilateral determination in the illustrated embodiment;

[0051] Fig. 9 For Figure 1 A schematic diagram of the signal processing principle of the security door in the illustrated embodiment;

[0052] Fig.10 For Fig. 9 A waveform example diagram of discrete amplitude information obtained in the signal processing principle shown;

[0053] Fig.11 For Fig. 9 Schematic diagram of the optimization process of the signal processing principle shown;

[0054] Fig.12 For Fig.11 A waveform example diagram of the interpolation amplitude information during the optimization process shown;

[0055] Fig.13 For Fig.11 An example waveform diagram of a continuous amplitude sequence obtained by the optimization process shown;

[0056] Fig.14 This is a test effect diagram when the first coil assembly and the second coil assembly work synchronously in the embodiment of the present application;

[0057] Fig.15 This is a test effect diagram of the embodiment of the present application using the first coil assembly and the second coil assembly to work in time sharing

[0058] Fig.16 This is a schematic diagram of an exemplary process of a metal detection method for a security door in an embodiment of the present application;

[0059] Fig.17 For Fig.16 Schematic diagram of the optimization process of the metal detection method shown;

[0060] Fig.18 This is a schematic diagram of an exemplary structure of a metal detection device for a security door in an embodiment of the present application. DETAILED DESCRIPTION

[0061] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and examples.

[0062] Figure 1 This is an exemplary structural diagram of a security door in one embodiment of the present application. Figure 1 In one embodiment of the present application, the security door may include a door panel assembly 10 , a sensing assembly 20 and a control assembly 50 .

[0063] The door panel assembly 10 may include a first door panel 11 and a second door panel 12 respectively arranged on opposite sides of the detection channel 100 in the width direction X. Moreover, in the embodiment of the present application, the door panel assembly 10 may also include a top panel 13 covering the detection channel 100, the top panel 13 may be connected between the top ends of the first door panel 11 and the second door panel 12 in the vertical direction Z, the top panel 13 may be equipped with a control box, and the control assembly 50 may be accommodated in the control box installed in the top panel 13.

[0064] The induction component 20 may include a first coil component 21 and a second coil component 22, the first coil component 21 includes a first receiving coil 211 arranged on the first door panel 11, and a first transmitting coil 212 arranged on the second door panel 12, and the second coil component 22 includes a second receiving coil 221 arranged on the second door panel 12, and a second transmitting coil 222 arranged on the first door panel 11. In the illustrated expression of the embodiment of the present application, the first receiving coil 211 includes a plurality of coils arranged in an array on the first door panel 11, the second receiving coil 221 includes a plurality of coils arranged in an array on the second door panel 12, the first transmitting coil 212 is configured as a single coil surrounding the second receiving coil 221 along the edge of the second door panel 12, and the second transmitting coil 222 is configured as a single coil surrounding the first receiving coil 211 along the edge of the first door panel 11, but it can be understood that the deployment mode and form of the first receiving coil 211, the second receiving coil 221, the first transmitting coil 212 and the second transmitting coil 222 are not limited to the illustrated expression of the embodiment of the present application.

[0065] The control component 50 may include any logic device such as FPGA (Field Programmable Gate Array), and / or a processor with data processing capabilities such as CPU (Central Processing Unit) and MCU (Microcontroller Unit).

[0066] The control component 50 is used to control the induction component 20. For example, the control component 50 can generate a transmission signal for the first transmitting coil 212 and the second transmitting coil 222 to generate a primary magnetic field in the detection channel 100 through the transmitting circuit 30, and the control component 50 can also obtain the receiving signal (or eddy current signal) generated by the first receiving coil 211 and the second receiving coil 221 through magnetic induction through the receiving circuit 40. It can be understood that the receiving circuit 40 can include multiple parallel transmission links to achieve multi-coil parallel reception of the first receiving coil 211 and the second receiving coil 221.

[0067] Moreover, in order to save power consumption of the security door, the control component 50 can control the sensing component 20 to start only during the detection period when the target to be detected passes through the detection channel 100 along the depth direction Y of the security door. For example, the security door can also include a first sensor arranged at the entrance side of the detection channel 100 in the depth direction Y of the security door, and a second sensor arranged at the exit side of the detection channel in the depth direction Y of the security door. Any one of the first sensor and the second sensor can include a non-contact sensor such as an infrared sensor or a photoelectric sensor, and the control component 50 can determine the start of the detection period in response to a first trigger signal generated by the first sensor when the target to be detected passes through its sensing range (i.e., the target to be detected enters the detection channel 100), and determine the end of the detection period in response to a second trigger signal generated by the second sensor when the target to be detected passes through its sensing range (i.e., the target to be detected leaves the detection channel 100).

[0068] In the embodiment of the present application, the control component 50 can control (for example, during the detection period) the first coil component 21 and the second coil component 22 to work in a first time slot and a second time slot of an alternating cycle, respectively. For example, the duration of the first time slot and the second time slot can be in the millisecond level. Figure 1 In the figure, the two dotted lines between the control component 50 and the first coil component 21 and the second coil component 22 are used to indicate that the control component 50 enables the first coil component 21 and the second coil component 22, and the pulse symbols at the two dotted lines are used to indicate that the first coil component 21 and the second coil component 22 are controlled by the enabling state of the control component 50. Figure 1 It can be clearly seen from the pulse symbols in that the enabling state Enb_asm1 of the first coil assembly 21 and the enabling state Enb_asm2 of the second coil assembly 22 are interlaced and complementary, that is, the first time slot when the first coil assembly 21 is enabled and the second time slot when the second coil assembly 22 is enabled are complementary time slots.

[0069] Accordingly, the transmission signal generated by the control component 50 through the transmission circuit 30 may include a first discrete transmission signal Dis_emt1 used in the first time slot for the first transmitting coil 212 to generate a primary magnetic field in the detection channel 100, and a second discrete transmission signal Dis_emt2 used in the second time slot for the second transmitting coil 222 to generate a primary magnetic field in the detection channel 100. That is, the control component 50 may be used to: generate the first discrete transmission signal Dis_emt1 used to drive the first transmitting coil 212 in the first time slot, and generate the second discrete transmission signal Dis_emt2 used to drive the second transmitting coil 222 in the second time slot.

[0070] Figure 2 For Figure 1 The waveform example of the discrete received signal obtained by the security gate in the embodiment shown is shown. Figure 2 , similar to the transmitting signal, the receiving signal acquired by the control component 50 through the receiving circuit 40 may include the first discrete receiving signal (or called the first discrete eddy current signal) Dis_rec1 generated by the first receiving coil 211 in the first time slot, and the second discrete receiving signal (or called the second discrete eddy current signal) Dis_rec2 generated by the second receiving coil 221 in the second time slot. That is, the control component 50 can be used to: acquire the first discrete receiving signal Dis_rec1 obtained by the first receiving coil 211 inducing the physical magnetic field in the detection channel 100 in the first time slot, and the second discrete receiving signal Dis_rec2 obtained by the second receiving coil 221 inducing the physical magnetic field in the detection channel 100 in the second time slot.

[0071] Figure 3 For Figure 1 The first example schematic diagram of the transceiver circuit structure of the security door in the embodiment shown. Figure 3 In an embodiment of the present application, the transmitting circuit 30 may include a first transmitting circuit 31 connected between the control component 50 and the first transmitting coil 212, and a second transmitting circuit 32 connected between the control component 50 and the second transmitting coil 222, and the receiving circuit 40 may include a first receiving circuit 41 connected between the control component 50 and the first receiving coil 211, and a second receiving circuit 42 connected between the control component 30 and the second receiving coil 221. Moreover, in Figure 3 In the first example shown, the control component 50 can be specifically configured to: activate the first transmitting circuit 31 and the first receiving circuit 41, turn off the second transmitting circuit 32 and the second receiving circuit 42 in the first time slot, and activate the second transmitting circuit 32 and the second receiving circuit 42, turn off the first transmitting circuit 31 and the first receiving circuit 42 in the second time slot.

[0072] like Figure 3As shown, the first transmitting circuit 31 and the second transmitting circuit 32 may include a full-bridge drive circuit 30a, a gate isolation circuit 30b, a full-bridge inverter circuit 30c and an impedance matching circuit 30d sequentially cascaded from the control component 50 to the first transmitting coil 212 or the second transmitting coil 222. Among them, the control component 50 can generate PWM (Pulse Width Modulation) signals to the full-bridge drive circuit 30a of the first transmitting circuit 31 and the second transmitting circuit 32 alternately in the first time slot and the second time slot. For example, the control component 50 may include a timing control module 51 and a signal transmission module 53 integrated in an FPGA, the signal transmission module 53 is controlled by the timing control module 51, and the signal transmission module 53 can generate a PWM signal to the full-bridge drive circuit 30a of the first transmitting circuit 31 in the first time slot and generate a PWM signal to the full-bridge drive circuit 30a of the second transmitting circuit 32 in the second time slot under the control of the timing control module 51. For another example, the PWM signal generated by the control component 50 (i.e., the signal transmitting module 53) may include two complementary PWM signals with dead zones to prompt the full-bridge drive circuit 30a to generate an excitation pulse signal to the gate of the MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) of the full-bridge inverter circuit 30.

[0073] and, Figure 3 The gate isolation circuit 30b shown in the figure is used to prevent the gate of the MOSFET of the full-bridge inverter circuit 30 from being impacted by the oscillating voltage; the full-bridge inverter circuit 30 can use the gate voltage change of the MOSFET to generate an AC voltage signal (ie, the first discrete emission signal Dis_emt1 or the second discrete emission signal Dis_emt2).

[0074] Specifically, the AC voltage signal (i.e., the first discrete transmitting signal Dis_emt1) generated by the full-bridge inverter circuit 30c in the first transmitting circuit 31 in the first time slot is output to the first transmitting coil 212 after impedance matching by the impedance matching circuit 30d, so that the first transmitting coil 212 generates a primary magnetic field located in the detection channel 100 in the first time slot; similarly, the AC voltage signal (i.e., the second discrete transmitting signal Dis_emt2) generated by the full-bridge inverter circuit 30 of the second transmitting circuit 32 in the second time slot is output to the second transmitting coil 222 after impedance matching by the impedance matching circuit 30d, so that the second transmitting coil 222 generates a primary magnetic field located in the detection channel 100 in the second time slot.

[0075] Still see Figure 3, the first receiving circuit 41 and the second receiving circuit 42 may include a limiting circuit 40a, an amplifying circuit 40b, a bandpass filtering circuit 40c and an analog-to-digital conversion circuit 40d which are sequentially cascaded from the first receiving coil 211 or the second receiving coil 221 to the control component 50. The limiting circuit 40a is used to limit the amplitude of the analog eddy current signal generated by the first receiving coil 211 in the first time slot or the second receiving coil 221 in the second time slot, so as to avoid the overshoot voltage in the analog eddy current signal from impacting the first receiving circuit 41 or the second receiving circuit 42; the analog eddy current signal is input to the analog-to-digital conversion circuit 40d after the signal amplification processing of the amplifying circuit 40b and the filtering processing of the bandpass filtering circuit 40c, and is converted into a discrete digital signal (i.e., the first discrete receiving signal Dis_rec1 or the second discrete receiving signal Dis_rec2) by the analog-to-digital conversion circuit 40d. Accordingly, the control component 50 can obtain the first discrete receiving signal Dis_rec1 from the analog-to-digital conversion circuit 40d of the first receiving circuit 41 in the first time slot, and obtain the second discrete receiving signal Dis_rec2 from the analog-to-digital conversion circuit 40d of the second receiving circuit 42 in the second time slot. For example, the control component 50 can also include a data acquisition module 54 integrated into the FPGA, the data acquisition module 54 is controlled by the timing control module 51, and the data acquisition module 54 can, under the control of the timing control module 51, obtain the first discrete receiving signal Dis_rec1 from the digital-to-analog conversion circuit 40d of the first receiving circuit 41 in the first time slot, and obtain the second discrete receiving signal Dis_rec2 from the analog-to-digital conversion circuit 40d of the second receiving circuit 42 in the second time slot.

[0076] Figure 4 For Figure 1 A second example schematic diagram of the transceiver circuit structure of the security door in the embodiment shown. Figure 4 In an embodiment of the present application, the transmitting circuit 30 may include a third transmitting circuit 33 connected to the control component 50, and the third transmitting circuit 33 may include the full-bridge drive circuit 30a, the gate isolation circuit 30b, the full-bridge inverter circuit 30c and the impedance matching circuit 30d described above; and the receiving circuit 40 may include a third receiving circuit 43 connected to the control component 50, and the third receiving circuit 43 may include the limiting circuit 40a, the amplifying circuit 40b, the bandpass filtering circuit 40c and the analog-to-digital conversion circuit 40d described above.

[0077] In an embodiment of the present application, the third transmitting circuit 33 is connected to the first transmitting coil 212 and the second transmitting coil 222 through a first two-selection switch 35. For example, the impedance matching circuit 30d of the third transmitting circuit 33 can be connected to the first transmitting coil 212 and the second transmitting coil 222 through the first two-selection switch 35; the third receiving circuit 43 is connected to the first receiving coil 211 and the second receiving coil 221 through a second two-selection switch 45. For example, the limiting circuit 40a of the third receiving circuit 43 can be connected to the first receiving coil 211 and the second receiving coil 221 through the second two-selection switch 45.

[0078] In this case, the control component 50 can be specifically configured to control the first two-to-one switch 35 and the second two-to-one switch 45 so that: the third transmitting circuit 33 (for example, the impedance matching circuit 30d) is connected to the first transmitting coil 212 in the first time slot and is connected to the second transmitting coil 222 in the second time slot, and the third receiving circuit 43 (for example, the limiter circuit 40a) is connected to the first receiving coil 211 in the first time slot and is connected to the second receiving coil 221 in the second time slot. For example, in Figure 4 In the embodiment, the timing control module 51 of the control component 50 may not need to be like Figure 3 The signal transmission module 53 and the data acquisition module 54 are controlled as shown, so that the time-sharing control of the first coil assembly 21 and the second coil assembly 22 can be achieved by controlling the first two-to-one switch 35 and the second two-to-one switch 45.

[0079] Whether Figure 3 The first transmitting circuit 31 and the second transmitting circuit 32 shown in FIG. Figure 4 The third transmitting circuit 33 shown in the figure uses the full-bridge inverter circuit 30c as the driving circuit of the first transmitting coil 212 and the second transmitting coil 222. This is because the full-bridge inverter circuit has a response speed of nanoseconds (i.e., the on-off response speed of MOSFET). Therefore, the full-bridge inverter circuit 30c can be more suitable for the timing control of the first transmitting circuit 31 and the second transmitting circuit 32 working alternately at the nanosecond level, thereby ensuring the timing control accuracy of the first discrete transmitting signal Dis_emt1 and the second discrete transmitting signal Dis_emt2.

[0080] Figure 5 For Figure 3 and Figure 4 The example shown is based on the waveform example of the discrete transmission signal generated by the full-bridge inverter circuit. Figure 5 The MOSFET of the full-bridge inverter circuit 30 can support an inverter period with an accuracy level of 4 μm, and thus can support timing control of the first time slot and the second time slot based on a millisecond duration.

[0081] It is understandable that if Figure 3 and Figure 4 The example structure shown is only used to express that the security door in the embodiment of the present application can use transmitting circuits 30 and receiving circuits 40 with different structures to achieve time-sharing control of the first coil assembly 21 and the second coil assembly 22, and is not intended to make unnecessary restrictions on the structure of the transmitting circuit 30 and the receiving circuit 40.

[0082] Based on the time-sharing control method of the first coil assembly 21 and the second coil assembly 22, the signal strength of the first discrete receiving signal Dis_rec1 is used to characterize the first unilateral magnetic field strength of the physical magnetic field in the detection channel 100 on the side where the first door panel 11 is located, and the signal strength of the second discrete receiving signal Dis_rec2 is used to characterize the second unilateral magnetic field strength of the physical magnetic field in the detection channel 100 on the side where the second door panel is located.

[0083] When the first receiving coil 211 deployed on the first door panel 11 is working (i.e., the first time slot), the first transmitting coil 212 deployed on the second door panel 12 on the opposite side of the first receiving coil 211 generates a primary magnetic field, and the second transmitting coil 222 deployed on the same side of the first door panel 11 as the first receiving coil 211 is closed, so that the primary magnetic field included in the physical magnetic field in the detection channel 100 gradually decays from the second door panel 12 to the first door panel 11, and there is only a weak primary magnetic field attenuated along the width direction X across the detection channel 100 in the neighborhood space of the first receiving coil 211, and there is no strong primary magnetic field that has not been attenuated generated by the second transmitting coil 222 deployed on the same side of the first door panel 11, that is, the first unilateral magnetic field strength at least includes the strength of the weak primary magnetic field generated by the first transmitting coil 212 after the primary magnetic field is attenuated across the detection channel 100 along the width direction X;

[0084] When the second receiving coil 221 deployed on the second door panel 12 is working (i.e., the second time slot), the second transmitting coil 222 deployed on the first door panel 11 on the opposite side of the second receiving coil 221 generates a primary magnetic field, and the first transmitting coil 212 deployed on the same side of the second door panel 12 as the second receiving coil 221 is closed. Therefore, the primary magnetic field included in the physical magnetic field in the detection channel 100 gradually decays from the first door panel 11 to the second door panel 12, and there is only a weak primary magnetic field attenuated along the width direction X across the detection channel 100 in the neighborhood space of the second receiving coil 221, and there is no strong primary magnetic field that has not been attenuated generated by the first transmitting coil 212 deployed on the same side of the second door panel 12, that is, the second unilateral magnetic field strength at least includes the strength of the weak primary magnetic field generated by the second transmitting coil 222 after the primary magnetic field is attenuated along the width direction X across the detection channel 100.

[0085] That is, the primary magnetic field included in the physical magnetic field in the detection channel 100 is only the unilateral primary magnetic field generated alternately by the first transmitting coil 212 and the second transmitting coil 22 in the first time slot and the second time slot respectively, and the first receiving coil 211 and the second receiving coil 221 working in the first time slot and the second time slot respectively are both located in the attenuation area of ​​the unilateral primary magnetic field, that is, based on the time-sharing operation of the first coil assembly 21 and the second coil assembly 22 in the alternating first time slot and the second time slot respectively, the primary magnetic field intensity induced by the first receiving coil 211 and the second receiving coil 221 during operation can be reduced.

[0086] Therefore, if there is a target metal in the detection channel 100, even if the target metal is a small metal object with a relatively small volume, the secondary magnetic field generated by it may penetrate the attenuation area of ​​the unilateral primary magnetic field and be successfully sensed by the first receiving coil 211 in the first time slot, or by the second receiving coil 221 in the second time slot. Moreover, the secondary magnetic field successfully sensed by the first receiving coil 211 in the first time slot, or successfully sensed by the second receiving coil 221 in the second time slot, can be expressed as an intensity fluctuation of the first unilateral magnetic field intensity or the second unilateral magnetic field intensity, and the fluctuation amplitude of the intensity fluctuation is associated with the magnetic field intensity of the secondary magnetic field.

[0087] Based on the above reasons, in an embodiment of the present application, the control component 50 can also be used to: detect the intensity fluctuation of the first unilateral magnetic field strength and the second unilateral magnetic field strength based on the first discrete receiving signal Dis_rec1 and the second discrete receiving signal Dis_rec2. For example, the control component 50 can detect the intensity fluctuation of the first unilateral magnetic field strength and the second unilateral magnetic field strength compared with the primary magnetic field strength of the unilateral primary magnetic field based on the first discrete receiving signal Dis_rec1 and the second discrete receiving signal Dis_rec2, wherein the primary magnetic field strength of the unilateral primary magnetic field is associated with the signal strength of the transmitting signals (i.e., the first discrete transmitting signal Dis_emt1 and the second discrete transmitting signal Dis_emt2) alternately generated by the first transmitting coil 212 and the second transmitting coil in the first time slot and the second time slot respectively.

[0088] Since the primary magnetic field strength included in the first unilateral magnetic field strength or the second unilateral magnetic field strength is weakened to the attenuated strength of the unilateral primary magnetic field in the embodiment of the present application, the intensity ratio of the magnetic field strength of the secondary magnetic field generated by the target metal to the magnetic field strength of the primary magnetic field can be improved. If the signal component representing the intensity fluctuation in the first discrete received signal Dis_rec1 and the second discrete received signal Dis_rec2 is taken as the target signal, and the signal component representing the unilateral primary magnetic field strength in the first discrete received signal Dis_rec1 and the second discrete received signal Dis_rec2 is regarded as the interference signal, then the improvement of the intensity ratio of the magnetic field strength of the secondary magnetic field to the magnetic field strength of the primary magnetic field can help improve the signal-to-noise ratio of the above-mentioned target signal (i.e., the intensity fluctuation caused by the secondary magnetic field generated by the target metal).

[0089] Figure 6 For Figure 1 A signal-to-noise ratio curve diagram of a first discrete received signal in the illustrated embodiment. Figure 7 For Figure 1 The signal-to-noise ratio curve of the second discrete received signal in the embodiment shown. Figure 6 and Figure 7 :

[0090] If the target metal is located in the detection channel 100 close to the first door panel 11, the first receiving coil 211 has a higher sensitivity to the magnetic field strength of the secondary magnetic field generated by the target metal, and Figure 6 As shown, the intensity fluctuation caused by the secondary magnetic field in the first unilateral magnetic field intensity has a higher signal-to-noise ratio in the first discrete receiving signal Dis_rec1. For example, the signal-to-noise ratio of the intensity fluctuation caused by the secondary magnetic field in the first unilateral magnetic field intensity in the first discrete receiving signal Dis_rec1 may be exponentially related to the distance of the target metal relative to the first door panel 11 in the width direction X of the detection channel 100.

[0091] If the target metal is located in the detection channel 100 close to the second door panel 12, the second receiving coil 221 has a higher sensitivity to the magnetic field strength of the secondary magnetic field generated by the target metal, and Figure 7 As shown, the signal-to-noise ratio of the intensity fluctuation in the second unilateral magnetic field strength caused by the secondary magnetic field in the second discrete receiving signal Dis_rec2 is higher. For example, the signal-to-noise ratio of the intensity fluctuation in the second unilateral magnetic field strength caused by the secondary magnetic field in the second discrete receiving signal Dis_rec2 may be exponentially related to the distance of the target metal relative to the second door panel 12 in the width direction X of the detection channel 100.

[0092] That is, the magnetic field strength of the secondary magnetic field induced by the first receiving coil 211 and the second receiving coil 221 is associated with the distance of the target metal relative to the first receiving coil 211 and the second receiving coil 221 in the width direction of the detection channel 100, and the high signal-to-noise ratio characteristics of the first discrete receiving signal Dis_rec1 and the second discrete receiving signal Dis_rec2 are only effective on a single side of the detection channel 100 in the width direction X.

[0093] In order to integrate the high signal-to-noise ratio characteristics of the first discrete receiving signal Dis_rec1 and the second discrete receiving signal Dis_rec2, in an embodiment of the present application, the control component 50 can comprehensively consider the first unilateral magnetic field strength represented by the first discrete receiving signal Dis_rec1 and the second unilateral magnetic field strength represented by the second discrete receiving signal Dis_rec2 to detect whether there is target metal in the detection channel 100.

[0094] Figure 8 For Figure 1 The high signal-to-noise ratio curve diagram based on the bilateral unilateral determination in the embodiment shown. Figure 8 As shown, the control component 50 can use the first unilateral magnetic field strength represented by the first discrete receiving signal Dis_rec1 to detect and determine the target metal in the unilateral area on one side close to the first door panel 11 in the detection channel 100, and can use the second unilateral magnetic field strength represented by the second discrete receiving signal Dis_rec2 to detect and determine the target metal in the other unilateral area on the second side close to the second door panel 12 in the detection channel 100. Therefore, no matter where the target metal generates the secondary magnetic field in the width direction X of the detection channel 100, the signal-to-noise ratio of the intensity fluctuation caused by the secondary magnetic field can reach 100. Figure 6 and Figure 7 The high signal-to-noise ratio range.

[0095] That is, in an embodiment of the present application, in order to ensure that the target metal can be successfully detected at any position in the width direction of the detection channel 100 through effective induction of the secondary magnetic field generated by it, the control component 50 can also be used to: in response to the detection result that the fluctuation amplitude of the first unilateral magnetic field strength and / or the second unilateral magnetic field strength (for example, the intensity fluctuation of the first unilateral magnetic field strength and / or the second unilateral magnetic field strength compared to the primary magnetic field strength of the unilateral primary magnetic field) reaches the target amplitude, determine that there is target metal in the detection channel 100, that is, determine that the object to be detected currently passing through the detection channel 100 carries the target metal, wherein the target amplitude is used to characterize the magnetic field strength threshold of the secondary magnetic field generated by the target metal based on the primary magnetic field.

[0096] Furthermore, in an embodiment of the present application, the control component 50 can be further used to: generate an alarm signal in response to a detection event of the presence of target metal in the detection channel 100, wherein the alarm signal is used to characterize that the object to be detected currently passing through the detection channel 100 carries the target metal.

[0097] In an embodiment of the present application, in order to improve the accuracy of the intensity fluctuation based on which the unilateral decision is based, a signal component (ie, a target signal) for characterizing the intensity fluctuation may be extracted from the first discrete received signal Dis_rec1 and the second discrete received signal Dis_rec2 by signal demodulation.

[0098] Fig. 9 For Figure 1 Schematic diagram of the signal processing principle of the security door in the embodiment shown. Fig. 9 In an embodiment of the present application, the control component 50 (eg, the data acquisition module 54) may be specifically configured as follows:

[0099] Using the signal strength of the transmission signal (i.e., the first discrete transmission signal Dis_emt1 and the second discrete transmission signal Dis_emt2), the first discrete reception signal Dis_rec1 and the second discrete reception signal Dis_rec2 are subjected to signal demodulation S90 using the unilateral primary magnetic field as the carrier, that is, the first discrete reception signal Dis_rec1 is subjected to signal demodulation S90 using the unilateral primary magnetic field generated by the first transmitting coil 212 as the carrier, and the second discrete reception signal Dis_rec2 is subjected to signal demodulation S90 using the unilateral primary magnetic field generated by the second transmitting coil 222 as the carrier. For example, the signal demodulation S90 may include IQ (quadrature) demodulation.

[0100] Fig.10 For Fig. 9 The waveform example diagram of the discrete amplitude information obtained in the signal processing principle shown in FIG. Any one of the first discrete amplitude information ΔW_rec1 and the second discrete amplitude information ΔW_rec2 can have the following characteristics: Fig.10 The discrete waveform is shown.

[0101] Since the first discrete amplitude information ΔW_rec1 is obtained by demodulating the first discrete received signal Dis_rec1 representing the first unilateral magnetic field strength, the first discrete amplitude information ΔW_rec1 can be regarded as the intensity fluctuation remaining after removing the primary magnetic field strength of the unilateral primary magnetic field from the first unilateral magnetic field strength (i.e., the target signal mentioned above), that is, the first discrete amplitude information ΔW_rec1 can be used to represent the first fluctuation amplitude of the intensity fluctuation of the first unilateral magnetic field strength of the unilateral primary magnetic field generated by the first transmitting coil 212 on the first door panel 11 side compared to the primary magnetic field strength of the unilateral primary magnetic field.

[0102] Since the second discrete amplitude information ΔW_rec2 is obtained by demodulating the second discrete received signal Dis_rec2 characterizing the second unilateral magnetic field strength, the second discrete amplitude information ΔW_rec2 can be regarded as the intensity fluctuation remaining after removing the primary magnetic field strength of the unilateral primary magnetic field from the second unilateral magnetic field strength (i.e., the target signal mentioned above), that is, the second discrete amplitude information ΔW_rec2 can be used to characterize the second fluctuation amplitude of the intensity fluctuation of the second unilateral magnetic field strength of the unilateral primary magnetic field generated by the second transmitting coil 222 on the second door panel 12 side compared to the primary magnetic field strength of the unilateral primary magnetic field.

[0103] Therefore, please look back Fig. 9 , the control component 50 (such as the data acquisition module 54) can also be specifically configured as:

[0104] Based on the demodulation result of the signal demodulation S90, the intensity change of the first unilateral magnetic field strength of the unilateral primary magnetic field generated by the first transmitting coil 212 on the side of the first door panel 11 and the intensity change of the second unilateral magnetic field strength of the unilateral primary magnetic field generated by the second transmitting coil 222 on the side of the second door panel 12 are detected.

[0105] The demodulation result includes the first discrete amplitude information ΔW_rec1 obtained by performing the signal demodulation on the first discrete received signal Dis_rec1, and the second discrete amplitude information ΔW_rec2 obtained by performing the signal demodulation on the second discrete received signal Dis_rec2. Moreover, in an embodiment of the present application, the detection result indicating that the intensity fluctuation reaches the target amplitude generated by the control component 50 may include: at least one of the first fluctuation amplitude and the second fluctuation amplitude reaches the target amplitude ΔW_obj.

[0106] In an embodiment of the present application, there is a timing misalignment between the first discrete receiving signal Dis_rec1 and the second discrete receiving signal Dis_rec2. Therefore, there is also the same timing misalignment between the first discrete amplitude information ΔW_rec1 and the second discrete amplitude information ΔW_rec2. As a result, the unilateral judgment on the first door panel 11 side and the unilateral judgment on the second door panel 12 side are not synchronized.

[0107] If unilateral determination on the first door panel 11 side and unilateral synchronization on the second door panel 12 side are required, the control component 50 may be specifically configured as follows:

[0108] Perform discrete value continuity processing on the first discrete amplitude information ΔW_rec1 and the second discrete amplitude information ΔW_rec2;

[0109] By comparing the processing results of discrete numerical continuous processing with the target amplitude ΔW_obj, it is determined whether the first change amplitude of the intensity fluctuation of the first unilateral magnetic field strength of the unilateral primary magnetic field generated by the first transmitting coil 212 on the first door panel 11 side compared to the primary magnetic field strength of the unilateral primary magnetic field, and the second change amplitude of the intensity fluctuation of the second unilateral magnetic field strength of the unilateral primary magnetic field generated by the second transmitting coil 222 on the second door panel 12 side compared to the primary magnetic field strength of the unilateral primary magnetic field reach the target amplitude ΔW_obj.

[0110] The processing result of the discrete numerical value continuation processing includes: a first continuous amplitude sequence ΔW_seq1 obtained by performing the discrete numerical value continuation processing on the first discrete amplitude information ΔW_rec1, and a second continuous amplitude sequence ΔW_seq2 obtained by performing the discrete numerical value continuation processing on the second discrete amplitude information ΔW_rec1.

[0111] Fig.11 For Fig. 9 Schematic diagram of the optimization process of the signal processing principle shown. Fig.11 , the discrete numerical value continuous processing of the first discrete amplitude information ΔW_rec1 and the second discrete amplitude information ΔW_rec2 may include interpolation processing S91 and smoothing filtering S92 (such as bandpass filtering and / or sliding filtering), that is, the control component 50 may be specifically configured as follows:

[0112] The first discrete amplitude information ΔW_rec1 is interpolated S91 and smoothed S92 to obtain a first continuous amplitude sequence ΔW_seq1, that is, the first discrete amplitude information ΔW_rec1 is interpolated S91 to obtain first interpolation amplitude information ΔW_int1, and then the first interpolation amplitude information ΔW_int1 is smoothed S92 to obtain the first continuous amplitude sequence ΔW_seq1;

[0113] The second discrete amplitude information ΔW_rec2 is interpolated S91 and smoothed S92 to obtain a second continuous amplitude sequence ΔW_seq2, that is, the second discrete amplitude information ΔW_rec2 is interpolated S91 to obtain the second interpolation amplitude information ΔW_int2, and then the second interpolation amplitude information ΔW_int2 is smoothed S92 to obtain the second continuous amplitude sequence ΔW_seq2.

[0114] Fig.12 For Fig.11 The waveform example of the interpolation amplitude information in the optimization process is shown in FIG. The waveform of any one of the first interpolation amplitude information ΔW_int1 and the second interpolation amplitude information ΔW_int2 can be as follows: Fig.12 As shown by the thick solid line in , and Fig.12The dotted line in may represent the first discrete amplitude information ΔW_rec1 or the second discrete amplitude information ΔW_rec2.

[0115] based on Fig.12 As can be seen from the waveforms shown, in the embodiment of the present application, the interpolation processing of the first discrete amplitude information ΔW_rec1 and the second discrete amplitude information ΔW_rec2 by the control component 50 can include: determining the amplitude value at the end time of the previous valid time slot of each invalid time slot where information is missing as the amplitude value of the invalid time slot, that is, the amplitude value at each invalid time keeps the amplitude value at the end time of the previous valid time slot. Among them, the valid time slot of the first discrete amplitude information ΔW_rec1 is the first time slot, and the invalid time slot where information is missing is the second time slot, and conversely, the valid time slot of the second discrete amplitude information W_rec2 is the second time slot, and the invalid time slot where information is missing is the first time slot.

[0116] Fig.13 For Fig.11 The waveform of any one of the first continuous amplitude sequence ΔW_seq1 and the second continuous amplitude sequence ΔW_seq2 can be as follows: Fig.13 As shown, that is, the amplitude values ​​of the first continuous amplitude sequence ΔW_seq1 and the second continuous amplitude sequence ΔW_seq2 can both be presented as continuous smooth curves.

[0117] Fig.14 This is a test effect diagram when the first coil assembly and the second coil assembly work synchronously in the embodiment of the present application. Fig.14 Three tests on the same target metal are shown, namely, a test in which the target metal is placed at a first test position P1 in the detection channel 100 close to the first door panel 11 side, a test in which the target metal is placed at a second test position P2 in the detection channel 100 close to the second door panel 12 side, and a test in which the target metal is placed at a third test position P3 in the detection channel 100 that is equidistant from the first door panel 11 and the second door panel 12 (i.e., the middle position between the first door panel 11 and the second door panel 12).

[0118] See also Fig.14In the enabling states Enb_asm1 and Enb_asm2 in the detection channel 100, during the test process in which the target metal is placed at each of the first test position P1, the second test position P2 and the third test position P3, the control component 50 controls the first coil component 21 and the second coil component 22 to work synchronously and continuously through the transmitting circuit 30'. In this case, the primary magnetic field included in the physical magnetic field in the detection channel 100 is the bilateral primary magnetic field generated by the first transmitting coil 212 and the second transmitting coil 222 at the same time, and the control component 50 can simultaneously receive the first continuous receiving signal Seq_rec1 and the second continuous receiving signal Seq_rec2 respectively generated by the first receiving coil 211 and the second receiving coil 221 through the receiving circuit 40', and the control component 50 can obtain the first continuous amplitude sequence ΔW_seq1' and the second continuous amplitude sequence ΔW_seq2' by demodulating the first continuous receiving signal Seq_rec1 and the second continuous receiving signal Seq_rec2 with the bilateral primary magnetic field as the carrier.

[0119] Among them, since the intensity of the bilateral primary magnetic field is relatively high, the intensity fluctuation (i.e., the target signal) represented by the first continuous amplitude sequence ΔW_seq1' and the second continuous amplitude sequence ΔW_seq2' is lower than the magnetic field intensity ratio of the bilateral primary magnetic field (i.e., the signal-to-noise ratio of the first continuous received signal Seq_rec1 and the second continuous received signal Seq_rec2), so that:

[0120] During the test process in which the target metal is placed at the first test position P1 near the first door panel 11 in the detection channel 100, the fluctuation peak value R_ΔW_d1 of the secondary magnetic field generated by the target metal in the first continuous amplitude sequence ΔW_seq1' barely exceeds the target amplitude ΔW_obj, but the second continuous amplitude sequence ΔW_seq2' does not reach the target amplitude ΔW_obj because the second receiving coil 221 is too far away from the target metal;

[0121] During the test process in which the target metal is placed at the second test position P2 near the second door panel 12 in the detection channel 100, the fluctuation peak value R_ΔW_d2 of the secondary magnetic field generated by the target metal in the second continuous amplitude sequence ΔW_seq2' barely exceeds the target amplitude ΔW_obj, but the first continuous amplitude sequence ΔW_seq1' does not have an amplitude value that reaches the target amplitude ΔW_obj because the first receiving coil 211 is too far away from the target metal;

[0122] During the test process in which the target metal is placed at the third test position P3 in the detection channel 100, the first continuous amplitude sequence ΔW_seq1' does not have an amplitude value that reaches the target amplitude ΔW_obj because the first receiving coil 211 is too far away from the target metal. At the same time, the second continuous amplitude sequence ΔW_seq2' also does not have an amplitude value that reaches the target amplitude ΔW_obj because the second receiving coil 221 is too far away from the target metal.

[0123] Thus, in Fig.14 In the three test processes shown, missed detection of the target metal occurs at least in the third test position P3 (ie, the middle position between the first door panel 11 and the second door panel 12 ) and its adjacent positions.

[0124] Fig.15 This is a test effect diagram of the embodiment of the present application when the first coil assembly and the second coil assembly work in time sharing. Fig.15 3 tests on the same target metal are shown in FIG. 1 , i.e., a test in which the target metal is placed at a first test position P1 near the first door panel 11 in the detection channel 100, a test in which the target metal is placed at a second test position P2 near the second door panel 12 in the detection channel 100, and a test in which the target metal is placed at a third test position P3 equidistant from the first door panel 11 and the second door panel 12 in the detection channel 100 (i.e., the middle position between the first door panel 11 and the second door panel 12). And, Fig.15 The target metals used in Fig.14 The target metals used are the same.

[0125] See also Fig.15 In the enabling states Enb_asm1 and Enb_asm2 in the detection channel 100, during the test process in which the target metal is placed at each of the first test position P1, the second test position P2 and the third test position P3, the control component 50 controls the first coil component 21 and the second coil component 22 to work in the first time slot and the second time slot respectively in the manner described above. Therefore, as described above, the primary magnetic field included in the physical magnetic field in the detection channel 100 is a unilateral primary magnetic field generated alternately by the first transmitting coil 212 and the second transmitting coil 222 in a time-sharing manner, and the control component 50 can control the first coil component 21 and the second coil component 22 to work in the first time slot and the second time slot respectively in a time-sharing manner. Fig.11 In the manner shown, a first continuous amplitude sequence ΔW_seq1 and a second continuous amplitude sequence ΔW_seq2 are obtained based on the first discrete received signal Dis_rec1 and the second discrete received signal Dis_rec2.

[0126] Obviously, the control component 50 is Fig.15 The first discrete received signal Dis_rec1 and the second discrete received signal Dis_rec2 obtained in the test process shown in FIG. Fig.14 The first continuous received signal Seq_rec1 and the second continuous received signal Seq_rec2 obtained in the test process shown have a higher signal-to-noise ratio, so:

[0127] During the test process in which the target metal is placed at the first test position P1 near the first door panel 11 in the detection channel 100, the fluctuation peak value R_ΔW_s1 of the secondary magnetic field generated by the target metal in the first continuous amplitude sequence ΔW_seq1 greatly exceeds the target amplitude ΔW_obj and is higher than Fig.14 The fluctuation peak value R_ΔW_d1 barely exceeds ΔW_obj;

[0128] During the test process in which the target metal is placed at the second test position P2 near the second door panel 12 in the detection channel 100, the fluctuation peak value R_ΔW_s2 for characterizing the secondary magnetic field generated by the target metal in the second continuous amplitude sequence ΔW_seq2 greatly exceeds the target amplitude ΔW_obj and is higher than Fig.14 The fluctuation peak value R_ΔW_d2 barely exceeds ΔW_obj;

[0129] During the test process in which the target metal is placed at the third test position P3 in the detection channel 100 , the fluctuation peak values ​​R_ΔW_s3 of the first continuous amplitude sequence ΔW_seq1 and the second continuous amplitude sequence ΔW_seq2 both exceed the target amplitude ΔW_obj.

[0130] Thus, by Fig.15 and Fig.14 By comparison, it can be seen that the embodiments of the present application can reduce the probability of missed detection of target metals.

[0131] Fig.16 This is an exemplary flow chart of the metal detection method for security doors in the embodiment of the present application. Fig.16 In an embodiment of the present application, a security door using the metal detection method may include: Figure 1 The first coil assembly and the second coil assembly shown in the figure, the metal detection method can control the first coil assembly and the second coil assembly of the security door to work in a time-sharing manner in the first time slot and the second time slot of the alternating cycle, respectively, and the metal detection method includes:

[0132] S1610: Acquire a first discrete receiving signal obtained by the first receiving coil included in the first coil assembly sensing the physical magnetic field in the detection channel in the first time slot, and a second discrete receiving signal obtained by the second receiving coil included in the second coil assembly sensing the physical magnetic field in the detection channel in the second time slot.

[0133] S1630: Detect intensity fluctuations of the first unilateral magnetic field intensity and the second unilateral magnetic field intensity based on the first discrete received signal and the second discrete received signal.

[0134] For example, S1630 can detect the intensity fluctuation of the first unilateral magnetic field intensity and the second unilateral magnetic field intensity compared to the primary magnetic field intensity of the unilateral primary magnetic field based on the first discrete received signal and the second discrete received signal, wherein the primary magnetic field intensity of the unilateral primary magnetic field is associated with the signal strength of the transmission signals (i.e., the first discrete transmission signal and the second discrete transmission signal) alternately generated by the first transmitting coil and the second transmitting coil in the first time slot and the second time slot respectively.

[0135] S1650: In response to the detection result that the fluctuation amplitude of the intensity fluctuation of the first unilateral magnetic field intensity and / or the second unilateral magnetic field intensity reaches the target amplitude, determine that there is a target metal in the detection channel, wherein the target amplitude is used to characterize the magnetic field intensity threshold of the secondary magnetic field generated by the target metal based on the primary magnetic field.

[0136] Based on the above metal detection method, since the two sets of coil assemblies of the security inspection door are configured to work alternately in time-sharing, so that the primary magnetic field in the detection channel is a unilateral primary magnetic field generated by the transmitting coil in one set of coil assemblies, and the receiving coils in each set of coil assemblies are located in the attenuation area after the unilateral primary magnetic field crosses the detection channel during operation, the primary magnetic field intensity sensed by the receiving coil during operation can be reduced. Therefore, if there is a target metal in the detection channel, even if the target metal is a small metal object with a small volume, the secondary magnetic field generated by it may penetrate the attenuation area of ​​the unilateral primary magnetic field and be successfully sensed by the receiving coil, thereby helping to reduce the missed detection rate of the security inspection door.

[0137] Furthermore, in an embodiment of the present application, the metal detection method may also include a step performed after S1650: generating an alarm signal in response to a detection event of the presence of target metal in the detection channel, wherein the alarm signal is used to characterize that the object to be detected currently passing through the detection channel carries the target metal.

[0138] In an embodiment of the present application, in order to improve the accuracy of the intensity fluctuation on which the unilateral judgment is based, S1630 can extract the signal component used to characterize the intensity fluctuation as the target signal from the first discrete received signal and the second discrete received signal by means of signal demodulation; and / or, if unilateral judgment on the first door panel side and unilateral synchronization on the second door panel side are required, then S1630 can also perform discrete numerical continuity processing on the first discrete amplitude information and the second discrete amplitude information, and, by comparing the processing result of the discrete numerical continuity processing with the target amplitude, determine whether the first change amplitude of the intensity fluctuation of the first unilateral magnetic field intensity of the unilateral primary magnetic field generated by the first transmitting coil on the first door panel side compared to the primary magnetic field intensity of the unilateral primary magnetic field, and the second change amplitude of the intensity fluctuation of the second unilateral magnetic field intensity of the unilateral primary magnetic field generated by the second transmitting coil on the second door panel side compared to the primary magnetic field intensity of the unilateral primary magnetic field reach the target amplitude.

[0139] Fig.17 For Fig.16 Schematic diagram of the optimized metal detection method shown in Figure 1. Fig.17 If signal demodulation and discrete data continuous processing are introduced at the same time, the metal detection method in the embodiment of the present application may include:

[0140] S1610: Acquire a first discrete receiving signal obtained by the first receiving coil included in the first coil assembly sensing the physical magnetic field in the detection channel in the first time slot, and a second discrete receiving signal obtained by the second receiving coil included in the second coil assembly sensing the physical magnetic field in the detection channel in the second time slot.

[0141] S1631: Using the signal strength of the transmission signals alternately generated by the first transmitting coil and the second transmitting coil in the first time slot and the second time slot respectively, signal demodulation is performed on the first discrete receiving signal and the second discrete receiving signal using the unilateral primary magnetic field as the carrier, wherein the demodulation result includes first discrete amplitude information obtained by performing the above signal demodulation on the first discrete receiving signal, and second discrete amplitude information obtained by performing the above signal demodulation on the second discrete receiving signal.

[0142] That is, S1631 may perform signal demodulation on the first discrete received signal using the unilateral primary magnetic field generated by the first transmitting coil as a carrier, and perform signal demodulation on the second discrete received signal using the unilateral primary magnetic field generated by the second transmitting coil as a carrier. For example, signal demodulation may include IQ demodulation.

[0143] Moreover, the demodulation result obtained by S1631 through signal demodulation can be used to detect the intensity changes of the first unilateral magnetic field strength and the second unilateral magnetic field strength, wherein the first discrete amplitude information is used to characterize the first fluctuation amplitude of the first unilateral magnetic field strength compared with the primary magnetic field strength of the unilateral primary magnetic field, and the second discrete amplitude information is used to characterize the second fluctuation amplitude of the second unilateral magnetic field strength compared with the primary magnetic field strength of the unilateral primary magnetic field.

[0144] S1633: Perform discrete numerical value continuation processing on the first discrete amplitude information and the second discrete amplitude information, wherein the processing result of the discrete numerical value continuation processing includes: a first continuous amplitude sequence obtained by performing the discrete numerical value continuation processing on the first discrete amplitude information, and a second continuous amplitude sequence obtained by performing the discrete numerical value continuation processing on the second discrete amplitude information.

[0145] For example, S1633 may specifically include:

[0146] The first discrete amplitude information is interpolated and smoothed to obtain a first continuous amplitude sequence, that is, the first discrete amplitude information is interpolated to obtain first interpolation amplitude information, and then the first interpolation amplitude information is smoothed to obtain a first continuous amplitude sequence;

[0147] The second discrete amplitude information is interpolated and smoothed to obtain a second continuous amplitude sequence, that is, the second discrete amplitude information is interpolated to obtain the second interpolation amplitude information, and then the second interpolation amplitude information is smoothed to obtain the second continuous amplitude sequence.

[0148] Among them, S1633 interpolation processing of the first discrete amplitude information and the second discrete amplitude information includes: determining the amplitude value at the end time of the previous valid time slot of each invalid time slot where information is missing as the amplitude value of the invalid time slot, that is, the amplitude value at each invalid time remains the amplitude value at the end time of the previous valid time slot. For example, the valid time slot of the first discrete amplitude information ΔW_rec1 is the first time slot, and the invalid time slot where information is missing is the second time slot. Conversely, the valid time slot of the second discrete amplitude information W_rec2 is the second time slot, and the invalid time slot where information is missing is the first time slot.

[0149] Moreover, the smoothing filtering performed on the first interpolation amplitude information and the second interpolation amplitude information at S1633 may include bandpass filtering and / or sliding filtering, so that the amplitude values ​​of the first continuous amplitude sequence and the second continuous amplitude sequence can both be presented as continuous smooth curves.

[0150] S1635: By comparing the processing result of discrete numerical continuous processing with the target amplitude, determine whether the first change amplitude of the intensity fluctuation of the first unilateral magnetic field strength of the unilateral primary magnetic field generated by the first transmitting coil on the first door panel side compared to the primary magnetic field strength of the unilateral primary magnetic field, and the second change amplitude of the intensity fluctuation of the second unilateral magnetic field strength of the unilateral primary magnetic field generated by the second transmitting coil on the second door panel side compared to the primary magnetic field strength of the unilateral primary magnetic field have reached the target amplitude.

[0151] That is, the detection result indicating that the intensity fluctuation reaches the target amplitude may include: at least one of the first fluctuation amplitude of the first unilateral magnetic field intensity compared to the primary magnetic field intensity of the unilateral primary magnetic field, and the second fluctuation amplitude of the second unilateral magnetic field intensity compared to the primary magnetic field intensity of the unilateral primary magnetic field reaches the target amplitude.

[0152] S1650: In response to the detection result that the fluctuation amplitude of the intensity fluctuation of the first unilateral magnetic field intensity and / or the second unilateral magnetic field intensity reaches the target amplitude, determine that there is a target metal in the detection channel, wherein the target amplitude is used to characterize the magnetic field intensity threshold of the secondary magnetic field generated by the target metal based on the primary magnetic field.

[0153] Fig.18 This is an exemplary structural diagram of a metal detection device for a security door in an embodiment of the present application. Fig.18 In an embodiment of the present application, a security door using the metal detection device may include Figure 1 The first coil assembly and the second coil assembly shown in the figure, the metal detection device may include a timing control module 1800, which is used to control the first coil assembly and the second coil assembly of the security door to work in a first time slot and a second time slot of an alternating cycle respectively, and the metal detection method includes:

[0154] The signal acquisition module 1810 is used to: acquire a first discrete receiving signal obtained by the first receiving coil included in the first coil assembly sensing the physical magnetic field in the detection channel in the first time slot, and a second discrete receiving signal obtained by the second receiving coil included in the second coil assembly sensing the physical magnetic field in the detection channel in the second time slot.

[0155] The strength detection module 1830 is used to: detect the intensity fluctuation of the first unilateral magnetic field intensity and the second unilateral magnetic field intensity based on the first discrete received signal and the second discrete received signal. For example, the strength detection module 1830 can detect the intensity fluctuation of the first unilateral magnetic field intensity and the second unilateral magnetic field intensity compared with the primary magnetic field intensity of the unilateral primary magnetic field based on the first discrete received signal and the second discrete received signal, wherein the primary magnetic field intensity of the unilateral primary magnetic field is associated with the signal strength of the transmission signals (i.e., the first discrete transmission signal and the second discrete transmission signal) alternately generated by the first transmitting coil and the second transmitting coil in the first time slot and the second time slot respectively.

[0156] The target identification module 1850 is used to: determine the presence of target metal in the detection channel in response to the detection result that the fluctuation amplitude of the intensity fluctuation of the first unilateral magnetic field intensity and / or the second unilateral magnetic field intensity (for example, the intensity fluctuation of the first unilateral magnetic field intensity and / or the second unilateral magnetic field intensity compared to the primary magnetic field intensity of the unilateral primary magnetic field) reaches the target amplitude, wherein the target amplitude is used to characterize the magnetic field intensity threshold of the secondary magnetic field generated by the target metal based on the primary magnetic field.

[0157] Based on the above metal detection device, since the two sets of coil assemblies of the security inspection door are configured to work alternately in time sharing, so that the primary magnetic field in the detection channel is a unilateral primary magnetic field generated by the transmitting coil in one set of coil assemblies, and the receiving coils in each set of coil assemblies are located in the attenuation area after the unilateral primary magnetic field crosses the detection channel during operation, the primary magnetic field intensity sensed by the receiving coil during operation can be reduced. Therefore, if there is a target metal in the detection channel, even if the target metal is a small metal object with a small volume, the secondary magnetic field generated by it may penetrate the attenuation area of ​​the unilateral primary magnetic field and be successfully sensed by the receiving coil, thereby helping to reduce the missed detection rate of the security inspection door.

[0158] Further, in the embodiment of the present application, the metal detection device may also include Fig.18 The alarm trigger module shown in is used to: generate an alarm signal in response to a detection event of the presence of target metal in the detection channel, wherein the alarm signal is used to indicate that the object to be detected currently passing through the detection channel carries the target metal.

[0159] In an embodiment of the present application, in order to improve the accuracy of the intensity fluctuation based on which the unilateral decision is based, the intensity detection module 1830 can extract the signal component used to characterize the intensity fluctuation from the first discrete received signal and the second discrete received signal as the target signal by signal demodulation. That is, the intensity detection module 1830 can be specifically configured as follows:

[0160] The signal strength of the transmission signals alternately generated by the first transmitting coil and the second transmitting coil in the first time slot and the second time slot are used to demodulate the first discrete receiving signal and the second discrete receiving signal using the unilateral primary magnetic field as the carrier, wherein the demodulation result includes the first discrete amplitude information obtained by performing the above signal demodulation on the first discrete receiving signal and the second discrete amplitude information obtained by performing the above signal demodulation on the second discrete receiving signal.

[0161] That is, the strength detection module 1830 may perform signal demodulation on the first discrete received signal using the unilateral primary magnetic field generated by the first transmitting coil as a carrier, and may perform signal demodulation on the second discrete received signal using the unilateral primary magnetic field generated by the second transmitting coil as a carrier. For example, signal demodulation may include IQ demodulation.

[0162] Moreover, the demodulation result obtained by the intensity detection module 1830 through signal demodulation can be used to detect the intensity changes of the first unilateral magnetic field intensity and the second unilateral magnetic field intensity, wherein the first discrete amplitude information is used to characterize the first fluctuation amplitude of the first unilateral magnetic field intensity compared to the primary magnetic field intensity of the unilateral primary magnetic field, and the second discrete amplitude information is used to characterize the second fluctuation amplitude of the second unilateral magnetic field intensity compared to the primary magnetic field intensity of the unilateral primary magnetic field.

[0163] If unilateral judgment on the first door panel side and unilateral synchronization on the second door panel side are required, the intensity detection module 1830 can also perform discrete numerical continuous processing on the first discrete amplitude information and the second discrete amplitude information, and, by comparing the processing result of the discrete numerical continuous processing with the target amplitude, determine whether the first change amplitude of the intensity fluctuation of the first unilateral magnetic field strength of the unilateral primary magnetic field generated by the first transmitting coil on the first door panel side compared to the primary magnetic field strength of the unilateral primary magnetic field, and the second change amplitude of the intensity fluctuation of the second unilateral magnetic field strength of the unilateral primary magnetic field generated by the second transmitting coil on the second door panel side compared to the primary magnetic field strength of the unilateral primary magnetic field reach the target amplitude.

[0164] That is, the strength detection module 1830 may be specifically configured as follows:

[0165] The first discrete amplitude information and the second discrete amplitude information are subjected to discrete numerical value continuous processing, wherein the processing result of the discrete numerical value continuous processing includes: a first continuous amplitude sequence obtained by performing the discrete numerical value continuous processing on the first discrete amplitude information, and a second continuous amplitude sequence obtained by performing the discrete numerical value continuous processing on the second discrete amplitude information; and,

[0166] By comparing the processing result of the discrete value continuous processing with the target amplitude, it is determined whether the first change amplitude of the intensity fluctuation of the first unilateral magnetic field intensity of the unilateral primary magnetic field generated by the first transmitting coil on the first door panel side compared with the primary magnetic field intensity of the unilateral primary magnetic field, and the second change amplitude of the intensity fluctuation of the second unilateral magnetic field intensity of the unilateral primary magnetic field generated by the second transmitting coil on the second door panel side compared with the primary magnetic field intensity of the unilateral primary magnetic field have reached the target amplitude. That is, the detection result indicating that the intensity fluctuation has reached the target amplitude may include: at least one of the first fluctuation amplitude of the first unilateral magnetic field intensity compared with the primary magnetic field intensity of the unilateral primary magnetic field, and the second fluctuation amplitude of the second unilateral magnetic field intensity compared with the primary magnetic field intensity of the unilateral primary magnetic field has reached the target amplitude.

[0167] For example, the discrete data continuous processing performed by the intensity detection module 1830 may specifically include:

[0168] The first discrete amplitude information is interpolated and smoothed to obtain a first continuous amplitude sequence, that is, the first discrete amplitude information is interpolated to obtain first interpolation amplitude information, and then the first interpolation amplitude information is smoothed to obtain a first continuous amplitude sequence;

[0169] The second discrete amplitude information is interpolated and smoothed to obtain a second continuous amplitude sequence, that is, the second discrete amplitude information is interpolated to obtain the second interpolation amplitude information, and then the second interpolation amplitude information is smoothed to obtain the second continuous amplitude sequence.

[0170] The interpolation processing of the first discrete amplitude information and the second discrete amplitude information by the intensity detection module 1830 includes: determining the amplitude value at the end time of the previous valid time slot of each invalid time slot where information is missing as the amplitude value of the invalid time slot, that is, the amplitude value at each invalid time remains the amplitude value at the end time of the previous valid time slot. For example, the valid time slot of the first discrete amplitude information ΔW_rec1 is the first time slot, and the invalid time slot where information is missing is the second time slot. Conversely, the valid time slot of the second discrete amplitude information W_rec2 is the second time slot, and the invalid time slot where information is missing is the first time slot.

[0171] Moreover, the smoothing filtering performed by the intensity detection module 1830 on the first interpolation amplitude information and the second interpolation amplitude information may include bandpass filtering and / or sliding filtering, so that the amplitude values ​​of the first continuous amplitude sequence and the second continuous amplitude sequence can both be presented as continuous smooth curves.

[0172] In another embodiment of the present application, a non-transitory computer-readable storage medium is provided. The non-transitory computer-readable storage medium stores instructions. When the instructions are executed by a processor, the processor executes the metal detection method as described above.

[0173] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A security door, characterized in that: include: The door panel assembly comprises a first door panel and a second door panel respectively arranged on opposite sides of the detection channel in the width direction; an induction component, comprising a first coil component and a second coil component, wherein the first coil component comprises a first receiving coil arranged on the first door panel and a first transmitting coil arranged on the second door panel, and the second coil component comprises a second receiving coil arranged on the second door panel and a second transmitting coil arranged on the first door panel; A control component is used to control the first coil component and the second coil component to work in a first time slot and a second time slot of an alternating cycle respectively, and is also used to: Obtain a first discrete receiving signal obtained by the first receiving coil inducing the physical magnetic field in the detection channel in the first time slot, and a second discrete receiving signal obtained by the second receiving coil inducing the physical magnetic field in the second time slot, wherein the signal strength of the first discrete receiving signal is used to characterize the first unilateral magnetic field strength of the physical magnetic field on the side where the first door panel is located, and the signal strength of the second discrete receiving signal is used to characterize the second unilateral magnetic field strength of the physical magnetic field on the side where the second door panel is located, and the physical magnetic field includes the unilateral primary magnetic field alternately generated by the first transmitting coil and the second transmitting coil in the first time slot and the second time slot respectively; Based on the first discrete received signal and the second discrete received signal, detecting intensity fluctuations of the first unilateral magnetic field intensity and the second unilateral magnetic field intensity; In response to the detection result that the fluctuation amplitude of the intensity fluctuation reaches the target amplitude, it is determined that the target metal exists in the detection channel, wherein the target amplitude is used to characterize the magnetic field intensity threshold of the secondary magnetic field generated by the target metal based on the unilateral primary magnetic field.

2. The security door according to claim 1, characterized in that: The control component is specifically configured as follows: Based on the first discrete received signal and the second discrete received signal, the intensity fluctuation of the first unilateral magnetic field strength and the second unilateral magnetic field strength compared to the primary magnetic field strength of the unilateral primary magnetic field is detected, wherein the primary magnetic field strength is associated with the signal strength of the transmission signal alternately generated by the first transmitting coil and the second transmitting coil.

3. The security door according to claim 2, characterized in that: The control component is specifically configured as follows: Using the signal strength of the transmission signal, the first discrete reception signal and the second discrete reception signal are demodulated using the unilateral primary magnetic field as a carrier; Based on the demodulation result of the signal demodulation, detecting the intensity change of the first unilateral magnetic field intensity and the second unilateral magnetic field intensity; The demodulation result includes first discrete amplitude information obtained by demodulating the first discrete received signal, and second discrete amplitude information obtained by demodulating the second discrete received signal, the first discrete amplitude information is used to characterize the first fluctuation amplitude of the first unilateral magnetic field intensity compared to the primary magnetic field intensity, the second discrete amplitude information is used to characterize the second fluctuation amplitude of the second unilateral magnetic field intensity compared to the primary magnetic field intensity, and the detection result of the intensity fluctuation reaching the target amplitude includes at least one of the first fluctuation amplitude and the second fluctuation amplitude reaching the target amplitude.

4. The security door according to claim 3, characterized in that: The control component is specifically configured as follows: Performing discrete value continuity processing on the first discrete amplitude information and the second discrete amplitude information; Determine whether the first change range and the second change range reach the target range by comparing the processing result of the discrete value continuous processing with the target range; The processing result of the discrete numerical value continuation processing includes: a first continuous amplitude sequence obtained by performing the discrete numerical value continuation processing on the first discrete amplitude information, and a second continuous amplitude sequence obtained by performing the discrete numerical value continuation processing on the second discrete amplitude information.

5. The security door according to claim 4, characterized in that: The control component is specifically configured as follows: performing interpolation processing and smoothing filtering on the first discrete amplitude information successively to obtain the first continuous amplitude sequence; performing interpolation processing and smoothing filtering on the second discrete amplitude information successively to obtain the second continuous amplitude sequence; The interpolation processing of the first discrete amplitude information and the second discrete amplitude information includes: determining the amplitude value at the end time of the previous valid time slot of each invalid time slot where information is missing as the amplitude value of the invalid time slot.

6. The security door according to claim 1, characterized in that: The control component is further used to: In response to a detection event of the target metal in the detection channel, an alarm signal is generated, wherein the alarm signal is used to indicate that the object to be detected currently passing through the detection channel carries the target metal.

7. The security door according to claim 1, characterized in that: The invention also includes a first transmitting circuit connected between the control component and the first transmitting coil, a second transmitting circuit connected between the control component and the second transmitting coil, a first receiving circuit connected between the control component and the first receiving coil, and a second receiving circuit connected between the control component and the second receiving coil, wherein the first transmitting circuit and the second transmitting circuit both include a full-bridge inverter circuit, and the control component is specifically configured to: activate the first transmitting circuit and the first receiving circuit in the first time slot, and turn off the second transmitting circuit and the second receiving circuit, and activate the second transmitting circuit and the second receiving circuit in the second time slot, and turn off the first transmitting circuit and the first receiving circuit; or, The invention also includes a third transmitting circuit and a third receiving circuit connected to the control component, wherein the third transmitting circuit is connected to the first transmitting coil and the second transmitting coil through a first two-select-one switch, the third transmitting circuit includes a full-bridge inverter circuit, and the third receiving circuit is connected to the first receiving coil and the second receiving coil through a second two-select-one switch. In addition, the control component is specifically configured to control the first two-select-one switch and the second two-select-one switch so that: the third transmitting circuit is connected to the first transmitting coil in the first time slot and is connected to the second transmitting coil in the second time slot, and the third receiving circuit is connected to the first receiving coil in the first time slot and is connected to the second receiving coil in the second time slot.

8. A metal detection method for a security door, characterized in that: The security door comprises a door panel assembly and a sensing assembly, wherein the door panel assembly comprises a first door panel and a second door panel respectively arranged on opposite sides of a detection channel in a width direction, the sensing assembly comprises a first coil assembly and a second coil assembly, the first coil assembly comprises a first receiving coil arranged on the first door panel, and a first transmitting coil arranged on the second door panel, and the second coil assembly comprises a second receiving coil arranged on the second door panel, and a second transmitting coil arranged on the first door panel, the metal detection method controls the first coil assembly and the second coil assembly to work in a first time slot and a second time slot of an alternating cycle respectively, and the metal detection method comprises: Obtain a first discrete receiving signal obtained by the first receiving coil inducing the physical magnetic field in the detection channel in the first time slot, and a second discrete receiving signal obtained by the second receiving coil inducing the physical magnetic field in the second time slot, wherein the signal strength of the first discrete receiving signal is used to characterize the first unilateral magnetic field strength of the physical magnetic field on the side where the first door panel is located, and the signal strength of the second discrete receiving signal is used to characterize the second unilateral magnetic field strength of the physical magnetic field on the side where the second door panel is located, and the physical magnetic field includes the unilateral primary magnetic field alternately generated by the first transmitting coil and the second transmitting coil in the first time slot and the second time slot respectively; Based on the first discrete received signal and the second discrete received signal, detecting intensity fluctuations of the first unilateral magnetic field intensity and the second unilateral magnetic field intensity; In response to the detection result that the fluctuation amplitude of the intensity fluctuation reaches the target amplitude, it is determined that the target metal exists in the detection channel, wherein the target amplitude is used to characterize the magnetic field intensity threshold of the secondary magnetic field generated by the target metal based on the unilateral primary magnetic field.

9. The metal detection method according to claim 8, characterized in that: The detecting, based on the first discrete received signal and the second discrete received signal, the intensity fluctuation of the first unilateral magnetic field intensity and the second unilateral magnetic field intensity comprises: Based on the first discrete received signal and the second discrete received signal, the intensity fluctuation of the first unilateral magnetic field strength and the second unilateral magnetic field strength compared to the primary magnetic field strength of the unilateral primary magnetic field is detected, wherein the primary magnetic field strength is associated with the signal strength of the transmission signal alternately generated by the first transmitting coil and the second transmitting coil.

10. The metal detection method according to claim 9, characterized in that: The detecting, based on the first discrete received signal and the second discrete received signal, the intensity fluctuation of the first unilateral magnetic field intensity and the second unilateral magnetic field intensity compared to the primary magnetic field intensity comprises: Using the signal strength of the transmission signal, the first discrete reception signal and the second discrete reception signal are demodulated using the unilateral primary magnetic field as a carrier; Based on the demodulation result of the signal demodulation, detecting the intensity change of the first unilateral magnetic field intensity and the second unilateral magnetic field intensity; The demodulation result includes first discrete amplitude information obtained by demodulating the first discrete received signal, and second discrete amplitude information obtained by demodulating the second discrete received signal, the first discrete amplitude information is used to characterize the first fluctuation amplitude of the first unilateral magnetic field intensity compared to the primary magnetic field intensity, the second discrete amplitude information is used to characterize the second fluctuation amplitude of the second unilateral magnetic field intensity compared to the primary magnetic field intensity, and the detection result of the intensity fluctuation reaching the target amplitude includes at least one of the first fluctuation amplitude and the second fluctuation amplitude reaching the target amplitude.

11. The metal detection method according to claim 10, characterized in that: The detecting, based on the demodulation result of the signal demodulation, the intensity change of the first unilateral magnetic field intensity and the second unilateral magnetic field intensity comprises: Performing discrete value continuity processing on the first discrete amplitude information and the second discrete amplitude information; Determine whether the first change range and the second change range reach the target range by comparing the processing result of the discrete value continuous processing with the target range; The processing result of the discrete numerical value continuation processing includes: a first continuous amplitude sequence obtained by performing the discrete numerical value continuation processing on the first discrete amplitude information, and a second continuous amplitude sequence obtained by performing the discrete numerical value continuation processing on the second discrete amplitude information.

12. The metal detection method according to claim 11, characterized in that: The step of performing discrete numerical value continuous processing on the first discrete amplitude information and the second discrete amplitude information includes: performing interpolation processing and smoothing filtering on the first discrete amplitude information successively to obtain the first continuous amplitude sequence; performing interpolation processing and smoothing filtering on the second discrete amplitude information successively to obtain the second continuous amplitude sequence; The interpolation processing of the first discrete amplitude information and the second discrete amplitude information includes: determining the amplitude value at the end time of the previous valid time slot of each invalid time slot where information is missing as the amplitude value of the invalid time slot.

13. The metal detection method according to claim 12, characterized in that: Also includes: In response to a detection event of the target metal in the detection channel, an alarm signal is generated, wherein the alarm signal is used to indicate that the object to be detected currently passing through the detection channel carries the target metal.

14. A metal detection device for a security door, characterized in that: The security door comprises a door panel assembly, a first coil assembly and a second coil assembly, the door panel assembly comprises a first door panel and a second door panel respectively arranged on opposite sides of a detection channel in a width direction, the first coil assembly comprises a first receiving coil arranged on the first door panel, and a first transmitting coil arranged on the second door panel, the second coil assembly comprises a second receiving coil arranged on the second door panel, and a second transmitting coil arranged on the first door panel, the first coil assembly and the second coil assembly work alternately at a preset frequency in time division, and the target metal detection device comprises: a signal acquisition module, used for acquiring a first discrete receiving signal obtained by the first receiving coil inducing the physical magnetic field in the detection channel in the first time slot, and a second discrete receiving signal obtained by the second receiving coil inducing the physical magnetic field in the second time slot, wherein the signal strength of the first discrete receiving signal is used to characterize the first unilateral magnetic field strength of the physical magnetic field on the side where the first door panel is located, and the signal strength of the second discrete receiving signal is used to characterize the second unilateral magnetic field strength of the physical magnetic field on the side where the second door panel is located, and the physical magnetic field includes the unilateral primary magnetic field alternately generated by the first transmitting coil and the second transmitting coil in the first time slot and the second time slot respectively; an intensity detection module, configured to detect intensity fluctuations of the first unilateral magnetic field intensity and the second unilateral magnetic field intensity based on the first discrete received signal and the second discrete received signal; A target identification module is used to determine the presence of target metal in the detection channel in response to a detection result that the fluctuation amplitude of the intensity fluctuation reaches a target amplitude, wherein the target amplitude is used to characterize the magnetic field intensity threshold of the secondary magnetic field generated by the target metal based on the unilateral primary magnetic field.

15. A non-transitory computer-readable storage medium, characterized in that The non-transitory computer-readable storage medium stores instructions which, when executed by a processor, cause the processor to perform the metal detection method of any one of claims 8 to 13.

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