Cold cathode x-ray baggage inspection apparatus, control method and program product

Abstract

The embodiment of the application relates to the technical field of security inspection, and discloses a cold cathode X-ray luggage security inspection instrument, a control method and a program product; the security inspection instrument comprises a cold cathode X-ray source and a conveying unit; the method comprises the following steps: acquiring load data and shape size data of a detected object, and monitoring conveying speed of the conveying unit in real time; calculating an equivalent density parameter of the detected object according to the load data and the shape size data; determining basic working parameters of the cold cathode X-ray source according to the equivalent density parameter; adjusting a negative secondary high-voltage amplitude in a negative secondary high-voltage circuit; simultaneously adjusting an output amplitude of a positive high-voltage circuit; performing dynamic exposure compensation on the cold cathode X-ray source according to the conveying speed; adjusting a duty cycle of a positive high-voltage output in the positive high-voltage circuit in real time; during beam emission of the cold cathode X-ray source, collecting high-energy signals and low-energy signals penetrating through the detected object, and generating an X-ray image, so that imaging quality is ensured, and device power consumption is significantly reduced.

Description

Technical Field

[0001] This application relates to the field of security inspection technology, and in particular to a cold cathode X-ray baggage security inspection device, control method and program product. Background Technology

[0002] X-ray security inspection equipment is widely used in airports, train stations, and logistics centers for non-contact inspection of luggage and parcels. Existing X-ray security scanners typically use thermionic cathode X-ray tubes as the radiation source. The working principle of a thermionic cathode X-ray tube is to use a heated filament to generate electrons, which are then accelerated in an electric field to bombard the anode target, producing X-rays. Due to the significant thermal inertia of the thermionic cathode, a long preheating time is required, making it impossible to achieve nanosecond or microsecond-level rapid switching. Therefore, existing security scanners typically keep the X-ray source continuously lit during operation, or can only perform low-frequency switching control.

[0003] In real-world security inspection scenarios, the types of objects being inspected are diverse, with vastly different physical properties. These range from low-density, large-volume clothing and blankets to high-density, small-volume metal devices or electronic products. Existing security scanners typically use fixed tube voltage and current parameters for beam scanning, unable to dynamically adjust based on the actual material characteristics of the object being inspected. When using high parameters to scan low-density objects, it easily leads to image overexposure, causing loss of detail in thin objects and resulting in energy waste and unnecessary radiation dose accumulation. When using low parameters to scan high-density objects, insufficient X-ray penetration results in large black areas in the image, making it difficult to effectively identify internal structures. This often necessitates security personnel to open and re-inspect the bags, reducing security inspection efficiency.

[0004] Furthermore, the operating speed of the transmission unit often fluctuates due to the load weight and motor performance. In traditional fixed-frequency control mode, changes in transmission speed cause alterations in the integral dose of X-rays per unit area of ​​the inspected object, leading to nonlinear fluctuations in image stretching, compression, or brightness, thus affecting the accuracy of subsequent material identification algorithms. Simultaneously, single-view X-ray imaging is prone to creating blind spots due to obstruction when dealing with stacked objects, making it difficult to accurately distinguish the material properties of overlapping areas. Summary of the Invention

[0005] One objective of this application is to provide a cold cathode X-ray baggage security scanner, control method, and program product, which at least solves the technical problems in the prior art where X-ray security scanners using fixed parameters for beam output cannot adapt to the diverse density characteristics of the inspected objects, resulting in poor image quality, energy waste, and image distortion caused by transmission speed fluctuations.

[0006] To achieve the above objectives, some embodiments of this application provide the following aspects:

[0007] In a first aspect, some embodiments of this application provide a control method for a cold cathode X-ray baggage scanner, the scanner comprising a cold cathode X-ray source and a transmission unit; the cold cathode X-ray source comprising a positive high-voltage circuit for controlling the high-voltage output time and a negative secondary high-voltage circuit for controlling the electron beam current magnitude; the method comprising:

[0008] The load data and external dimensions of the object under inspection are acquired, and the transmission speed of the transmission unit is monitored in real time.

[0009] Based on the load data and the external dimensions data, the equivalent density parameter of the inspected object is calculated;

[0010] Based on the equivalent density parameter, the basic operating parameters of the cold cathode X-ray source are determined; the amplitude of the negative secondary high voltage in the negative secondary high voltage circuit is adjusted to match the electron beam intensity corresponding to the equivalent density parameter; at the same time, the output amplitude of the positive high voltage circuit is adjusted to obtain the X-ray penetration power corresponding to the equivalent density parameter.

[0011] Based on the transmission speed, dynamic exposure compensation is performed on the cold cathode X-ray source; the duty cycle of the positive high voltage output is adjusted in real time in the positive high voltage circuit so that the duty cycle and the transmission speed maintain a preset proportional relationship;

[0012] During the beam output of the cold cathode X-ray source based on the duty cycle, high-energy and low-energy signals passing through the object under inspection are acquired, and an X-ray image is generated.

[0013] Secondly, some embodiments of this application also provide a cold cathode X-ray baggage security scanner, including:

[0014] A conveying unit is used to transport the object to be inspected. The conveying unit is equipped with a gravity sensor and a position sensor.

[0015] A size detection unit is disposed above or to the side of the conveying unit and is used to detect the external dimensions of the object being inspected.

[0016] A cold cathode X-ray source includes a cold cathode X-ray tube, a positive high-voltage circuit, and a negative secondary high-voltage circuit; the positive high-voltage circuit is configured to control the high-voltage output time by adjusting the duty cycle, and the negative secondary high-voltage circuit is configured to control the electron beam current by adjusting the voltage amplitude.

[0017] The detection unit includes a high-energy detector and a low-energy detector, used to acquire X-ray transmission signals;

[0018] The control unit is communicatively connected to the transmission unit, the size detection unit, the cold cathode X-ray source, and the detection unit.

[0019] The control unit is configured to perform the control method for the cold cathode X-ray baggage scanner described in any of the preceding claims.

[0020] Thirdly, some embodiments of this application also provide a computer program product, including a computer program / instructions that, when executed by a processor, implement the steps of the method described above.

[0021] Compared with related technologies, the solution provided in this application firstly calculates the equivalent density parameter of the inspected object by jointly acquiring load data and external dimension data, and then dynamically adjusts the negative secondary high voltage amplitude and positive high voltage output amplitude of the cold cathode X-ray source accordingly. For low-density objects, the system automatically reduces the electron beam current and X-ray penetration power to avoid image overexposure and improve soft tissue contrast; for high-density objects, the system automatically enhances penetration power and signal-to-noise ratio. This on-demand beam output control strategy significantly reduces equipment power consumption and extends the service life of the cold cathode X-ray tube while ensuring imaging quality, achieving green and energy-saving security inspection.

[0022] Secondly, by monitoring the conveyor speed in real time and dynamically adjusting the duty cycle of the positive high voltage output, the X-ray exposure time and conveyor speed maintain a precise proportional relationship. Regardless of whether the conveyor belt slows down due to heavy load or speeds up due to no load, the system can ensure a constant X-ray dose per unit scanning area, effectively eliminating motion blur and image distortion, and ensuring the accuracy of subsequent image processing data.

[0023] Then, by utilizing symmetrically arranged cold cathode X-ray sources and detection units on both sides, combined with time difference calculations from position sensors, precise registration of dual-view images in the spatial domain was achieved. For overlapping areas, the system does not simply superimpose images. Instead, based on a goodness-of-fit test, it compares the measured data distribution with a pre-set stepped sample R-IL curve, selecting the data from the side with the higher correlation coefficient as the judgment criterion. This effectively eliminates overlapping interference and improves the accuracy of automatic identification of hazardous and contraband materials.

[0024] Finally, by employing a single-source dual-energy detection architecture, the synchronous acquisition of high and low energy data is achieved using the principle of stratified absorption. Compared to traditional methods of rapid voltage switching, this application can acquire high and low energy signals without complex power modulation circuits. Combined with the stability of the cold cathode, it ensures strict spatiotemporal alignment of high and low energy images, providing a reliable data foundation for R-value calculation and material classification. Attached Figure Description

[0025] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0026] Figure 1 A flowchart illustrating an exemplary control method for a cold cathode X-ray baggage security scanner provided in some embodiments of this application;

[0027] Figure 2 A schematic diagram of a control method for a cold cathode X-ray source provided in some embodiments of this application;

[0028] Figure 3 A schematic diagram of the sensor position of a cold cathode X-ray baggage security scanner provided for some embodiments of this application;

[0029] Figure 4 A schematic diagram of the architecture of a cold cathode X-ray baggage security scanner provided for some embodiments of this application;

[0030] Figure 5 A schematic diagram of another cold cathode X-ray baggage security scanner provided in some embodiments of this application;

[0031] Figure 6 A schematic diagram of UPS connection in a cold cathode X-ray baggage security scanner provided for some embodiments of this application;

[0032] Figure 7 This is an exemplary structural diagram of the control unit in a cold cathode X-ray baggage security scanner provided in some embodiments of this application. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] Figure 1 The flowchart below illustrates an exemplary control method for a cold cathode X-ray baggage security scanner according to some embodiments of this application. The security scanner includes a cold cathode X-ray source and a transmission unit. The cold cathode X-ray source includes a positive high-voltage circuit for controlling the high-voltage output time and a negative secondary high-voltage circuit for controlling the electron beam current magnitude.

[0035] Specifically, such as Figure 2As shown, the cold cathode X-ray source mainly consists of a cold cathode X-ray tube, a positive high-voltage circuit, and a negative secondary high-voltage circuit. The cold cathode X-ray tube contains an anode, a cathode, and a grid (or focusing electrode), with the cathode grounded (GND). The positive high-voltage circuit is electrically connected to the anode and provides a positive high-voltage electric field to accelerate electrons; the negative secondary high-voltage circuit is electrically connected to the cathode or grid and provides a negative bias electric field to control electron emission. Specifically, the negative secondary high-voltage circuit controls the magnitude of the electron beam current (mA). It changes the potential barrier strength on the cathode surface by adjusting the voltage amplitude of the output negative pulse, thereby determining the number of electrons bombarding the anode per unit time. The positive high-voltage circuit has a dual adjustment function: on the one hand, it determines the energy (i.e., penetrating power) of the X-ray photons by adjusting the voltage amplitude (kV) of the output positive pulse; on the other hand, it precisely controls the X-ray beam exit window time by adjusting the duty cycle of the output positive pulse.

[0036] The control method includes:

[0037] S101. Obtain the load data and external dimension data of the object under inspection, and monitor the transmission speed of the transmission unit in real time.

[0038] Specifically, during the security check process initiation phase, step S101, acquiring basic information about the object to be inspected, is executed first. When the object is conveyed into the security check channel by the conveyor belt, a gravity sensor array located below the conveyor unit senses changes in the force on the conveyor belt in real time, converting the collected analog pressure signals into digital load data and uploading it. Simultaneously, a size detection unit (e.g., an infrared light curtain sensor or a laser contour scanner) located above the conveyor channel entrance is operational. When the object blocks the light curtain or reflects the laser signal, the size detection unit records the number of blocked beams and the duration of the blockage. Combined with the conveyor belt's running speed, it analyzes the object's length, width, and height dimensions. At the same time, a rotary encoder or speed sensor installed on the conveyor belt drive motor shaft monitors the instantaneous linear velocity of the conveyor unit in real time and feeds back the speed signal at a millisecond-level refresh rate as a reference for subsequent timing control.

[0039] S102. Calculate the equivalent density parameter of the object under test based on the load data and the external dimensions data.

[0040] Specifically, after receiving the aforementioned raw data, step S102, which calculates the equivalent density parameter, is executed. First, a three-dimensional envelope model of the object under test is constructed based on its external dimensions, and the volume of this model is calculated. Then, the load data uploaded by the gravity sensor is divided by the calculated volume value to obtain the equivalent density parameter, which reflects the overall material properties of the object under test. To achieve refined control, the calculated equivalent density parameter is compared with a density grading threshold preset in the memory to determine the density range to which the object under test belongs, such as a low-density lightweight range, a medium-density mixed range, or a high-density metallic range.

[0041] S103. Determine the basic operating parameters of the cold cathode X-ray source based on the equivalent density parameter; adjust the amplitude of the negative secondary high voltage in the negative secondary high voltage circuit to match the electron beam intensity corresponding to the equivalent density parameter; and simultaneously adjust the output amplitude of the positive high voltage circuit to obtain the X-ray penetration power corresponding to the equivalent density parameter.

[0042] Specifically, the preset density-source parameter mapping table is consulted to determine the basic operating parameters that match the current equivalent density parameters. The adjustment process is divided into two dimensions: In the electron beam intensity control dimension, a bias adjustment command is sent to the negative secondary high-voltage circuit of the cold cathode X-ray source. The negative secondary high-voltage circuit adjusts the negative bias amplitude (i.e., negative secondary high-voltage amplitude) applied to the cold cathode grid or focusing electrode according to the command. By changing the electric field emission barrier on the cathode surface, the number of electrons overflowing from the cold cathode surface is precisely controlled, so that the electron beam intensity is adapted to the density of the object under inspection (i.e., a larger density results in a larger beam current, and a smaller density results in a smaller beam current). In the X-ray penetration control dimension, a voltage amplitude adjustment command is simultaneously sent to the positive high-voltage circuit to adjust the DC high-voltage amplitude (i.e., output amplitude) output by the positive high-voltage circuit to the anode target. This changes the kinetic energy when electrons bombard the target, thereby outputting X-rays with corresponding hardness, ensuring that the rays can penetrate the object under inspection without producing excessive scattering background. In practical setups, the positive high voltage can be set between 80kV and 160kV, covering all detection needs from thin clothing to heavy metal components. The output voltage amplitude of the negative high voltage circuit is typically set between -1kV and -10kV (relative to the cathode potential). By linearly adjusting the amplitude of the negative high voltage, the tube current can be continuously adjusted from 0.1mA to 3.0mA. For example, when detecting a thick object, the system simultaneously increases the amplitude (i.e., increases the absolute value) of the negative high voltage while increasing the positive high voltage, increasing the electron beam current, thereby ensuring that the detector receives a sufficient number of transmitted photons and avoiding noise or shadows in the image.

[0043] S104. Perform dynamic exposure compensation on the cold cathode X-ray source according to the transmission speed; adjust the duty cycle of the positive high voltage output in real time in the positive high voltage circuit so that the duty cycle and the transmission speed maintain a preset proportional relationship.

[0044] Specifically, when the cold cathode X-ray source is turned on and in beam-emitting state, the dynamic exposure compensation step S104 is executed in parallel. The real-time transmission speed fed back from the rotary encoder is continuously read, and the real-time speed is compared with the standard reference speed set by the system using a PID control algorithm. When it is detected that the transmission speed is lower than the reference speed due to excessive luggage weight, a duty cycle correction signal is generated and sent to the modulation module of the positive high voltage circuit to reduce the duty cycle of the positive high voltage pulse output, thereby reducing the beam emission frequency or duration per unit time and preventing image overlap and overexposure caused by slow transmission. Conversely, when the transmission speed is higher than the reference speed, the duty cycle of the positive high voltage output is increased, thereby increasing the exposure per unit time. Through this real-time closed-loop adjustment, the linear proportional relationship between the positive high voltage duty cycle and the transmission speed is locked, ensuring that the total amount of X-ray photons received by the inspected object per unit distance moved in the transmission direction remains constant.

[0045] S105. During the beam output of the cold cathode X-ray source based on the duty cycle, high-energy signals and low-energy signals passing through the object under inspection are acquired, and an X-ray image is generated.

[0046] Finally, in step S105, while the cold cathode X-ray source operates according to the aforementioned optimized parameters, the detection unit (including a high-energy detector array and a low-energy detector array) located on the other side and bottom of the transmission channel receives X-ray photons that have penetrated the object being inspected. The scintillation crystal within the detection unit converts the X-rays into visible light, which is then converted into electrical signals by a photodiode. The data acquisition system (DAS) integrates, amplifies, and performs analog-to-digital conversion on these high-energy and low-energy signals, and streams the raw data for image processing. After image processing, the data is stitched together based on the trigger signal from the position sensor, ultimately reconstructing an X-ray image with consistent clarity, appropriate contrast, and no geometric distortion, which is then displayed on the display terminal.

[0047] It should be noted that the low-energy signal and high-energy signal do not refer to the cold cathode X-ray source emitting two different energies of radiation in a time-division manner, but rather to the spatial energy spectrum separation of the same continuous energy spectrum X-ray beam based on the stacked physical structure of the detection unit. Specifically, a single exposure of the cold cathode X-ray source produces a continuous spectrum of X-rays containing a wide energy band. The low-energy detector at the front end of the detection assembly preferentially absorbs and responds to the soft X-ray photons with weaker penetrating power in the energy spectrum, and its output is defined as the low-energy signal. Meanwhile, the hard X-ray photons, after the low-energy components have been filtered out by the intermediate filter, continue to propagate and are absorbed and responded to by the thick scintillator high-energy detector at the rear end, and its output is defined as the high-energy signal. By synchronously acquiring data from these two channels, the attenuation information of the same object under test in different energy domains can be obtained.

[0048] In this embodiment, the refined control process significantly improves the overall performance of the security inspection system. First, this method abandons the fixed-parameter exposure mode of traditional security inspection machines. It uses load and size data to infer object density and independently adjusts the tube voltage (determining penetration power) and tube current (determining signal-to-noise ratio) of the cold cathode, fundamentally solving the imaging problem of "overexposure of light objects and underexposure of heavy objects." This greatly improves the accuracy of material identification while achieving on-demand radiation dose output and reducing operating power consumption. Second, by utilizing the physical characteristics of the cold cathode X-ray source—namely, its lack of thermal inertia and ability to rapidly pulse modulate—a real-time tracking mechanism of positive high-voltage duty cycle to conveyor speed is established. This completely eliminates image stretching or compression distortion caused by conveyor belt load fluctuations, ensuring accurate geometrical reproduction of the security inspection image and providing a high-quality standard data source for subsequent AI-assisted image interpretation.

[0049] In one embodiment, the step of dynamically exposing the cold cathode X-ray source according to the transmission speed and adjusting the duty cycle of the positive high voltage output in real time in the positive high voltage circuit so that the duty cycle and the transmission speed maintain a preset proportional relationship specifically includes:

[0050] Set the standard transmission speed and the corresponding standard duty cycle;

[0051] Real-time acquisition of the current actual transmission speed;

[0052] The real-time duty cycle of the positive high voltage output is adjusted according to a preset compensation logic; wherein, when the actual transmission speed is greater than the standard transmission speed, the real-time duty cycle is increased; when the actual transmission speed is less than the standard transmission speed, the real-time duty cycle is decreased.

[0053] Specifically, during the system initialization or calibration phase of the security scanner, the standard operating conditions of the cold cathode X-ray source are first set. The operating speed of the transmission unit under rated load is set to the standard transmission speed, and the positive high-voltage output pulse duty cycle that achieves the best image clarity and signal-to-noise ratio at this speed is set to the standard duty cycle. The standard duty cycle determines the effective exposure time of each X-ray emission cycle at the standard transmission speed.

[0054] During the actual operation of the security scanner, a rotary encoder or speed sensor mounted on the drive shaft of the conveyor unit collects the current actual conveying speed of the conveyor belt in real time at a high frequency (e.g., once every 10 milliseconds) and uploads the speed data. The system internally runs a PID control algorithm or a proportional tracking algorithm to compare the actual conveying speed in real time. The numerical difference from the standard transmission speed V is calculated, and the target duty cycle that should be applied to the positive high voltage circuit at this time is calculated according to the preset linear compensation logic.

[0055] The specific adjustment logic is as follows: when the actual transmission speed is detected... When the conveyor speed exceeds the standard transport speed V (i.e., the conveyor belt accelerates), it means the inspected object passes through the imaging area faster, and the sampling points per unit space become sparser. At this time, a boost command is generated and sent to the modulation module of the positive high-voltage circuit to increase the real-time duty cycle of the positive high-voltage output, extending the X-ray beam exit time of a single pulse to compensate for the reduced integrated exposure due to the increased speed. Conversely, when the actual transport speed is monitored... When the conveyor speed is less than the standard transport speed V (i.e., the conveyor belt decelerates), it means that the time the object under inspection spends in the imaging area increases. At this time, a reduction command is generated to lower the real-time duty cycle of the positive high-voltage output, shortening the X-ray beam exit time of a single pulse and preventing image pixel overflow or geometric stretching due to overexposure. Through the above real-time closed-loop adjustment, the ratio of the real-time duty cycle to the actual transport speed is always maintained constant, ensuring that the spatial sampling rate of the X-ray source is strictly synchronized with the movement speed of the object under inspection.

[0056] In this embodiment, by utilizing the nanosecond-level rapid switching characteristics of the cold cathode X-ray source, the system establishes a real-time tracking mechanism for the positive high-voltage duty cycle in relation to the conveyor speed. Regardless of fluctuations in the conveyor belt speed, this mechanism ensures that the radiation dose received by the inspected object remains consistent per unit distance traveled in the conveyor direction. This not only eliminates stretching or compression distortion of the image in the conveyor direction, ensuring accurate aspect ratio reproduction of the inspected object in the X-ray image, but also ensures the linearity of the image grayscale values ​​(density information), providing high-quality, standardized raw data support for subsequent automatic contraband identification algorithms based on image texture features.

[0057] In one embodiment, the step of calculating the equivalent density parameter of the inspected object based on the load data and the external dimensions specifically includes:

[0058] The volume of the inspected object is calculated based on the aforementioned external dimensions.

[0059] The equivalent density parameter is obtained by calculating the ratio of the load data to the volume value.

[0060] Multiple density control intervals are preset, and each density control interval corresponds to a set of preset negative secondary high voltage amplitude and positive high voltage rated voltage;

[0061] Determine the density control range into which the equivalent density parameter falls, and call the corresponding parameters to control the cold cathode X-ray source.

[0062] Specifically, in the data processing stage, the internal volume calculation unit is first invoked to multiply the length, width, and height dimension data uploaded by the size detection unit to establish a three-dimensional envelope model of the inspected object and calculate its volume value. Subsequently, the load data collected by the gravity sensor is divided by the calculated volume value to obtain the equivalent density parameter reflecting the overall material density of the inspected object.

[0063] To achieve precise parameter matching, the system pre-establishes and stores a density control strategy table. This table divides the density range of objects the security scanner might encounter into multiple consecutive density control intervals. For example, the range with a density less than a first threshold is defined as a low-density, lightweight interval; the range with a density between the first and second thresholds is defined as a medium-density, mixed interval; and the range with a density greater than the second threshold is defined as a high-density, dense interval. For each density control interval, the system is bound to a set of experimentally calibrated basic operating parameters for the cold cathode X-ray source. These basic operating parameters specifically include the negative secondary high voltage amplitude used to control the electron beam current and the positive high voltage rated voltage used to control the X-ray penetration power.

[0064] In actual control, the equivalent density parameter calculated in real time is compared one by one with the thresholds at each level in the density control strategy table to determine which density control interval the equivalent density parameter falls into. Once the target interval is determined, the preset parameter group corresponding to the target interval is immediately invoked. If the determination result is a low-density, lightweight interval (e.g., clothing or empty boxes), a low-level control signal is sent to the negative high-voltage circuit to reduce the amplitude of the negative high voltage to decrease the electron beam current, while a low-voltage command is sent to the positive high-voltage circuit to reduce the output amplitude to output soft X-rays and prevent image overexposure. If the determination result is a high-density, dense interval (e.g., solid metal parts), the amplitude of the negative high voltage is increased to increase the electron beam current intensity, and the output amplitude of the positive high-voltage circuit is simultaneously increased to output hard X-rays to ensure that the rays can penetrate the inspected object. Through this table lookup and matching mechanism, the optimal parameter configuration for the material characteristics of the inspected object is completed before the X-ray source exits the beam.

[0065] In this embodiment, by pre-setting a density control range and establishing its mapping relationship with the negative secondary high voltage amplitude and positive high voltage, the system can automatically select the most suitable scanning energy and dose for luggage of different densities. This not only effectively avoids the phenomenon of low-density objects losing detail due to excessive radiation and high-density objects forming black patches due to insufficient radiation, ensuring image clarity and contrast across the entire density range; but also, this on-demand energy allocation control strategy significantly reduces unnecessary high-energy radiation to small and light objects, greatly reducing the overall power consumption of the system and alleviating the pressure on radiation protection shielding.

[0066] In one embodiment, the security inspection device employs dual-vision imaging, with cold cathode X-ray sources and corresponding detection units respectively arranged on the left and right sides of the transmission unit; the step of acquiring high-energy and low-energy signals transmitted through the inspected object during the beam emission of the cold cathode X-ray source specifically includes:

[0067] Control the cold cathode X-ray sources on the left and right sides to emit X-rays toward the object being inspected;

[0068] For each detection unit, the transmitted X-rays are separated and collected using the principle of layered absorption:

[0069] It receives and converts the low-energy components in X-rays to obtain a low-energy signal;

[0070] The residual radiation after absorption of low-energy components is subjected to energy spectrum hardening treatment;

[0071] The hardened high-energy components are received and converted to obtain a high-energy signal.

[0072] Specifically, the security scanner has a first cold cathode X-ray source and a second cold cathode X-ray source installed on the left and right sides of the transmission unit, respectively, and a first detection unit and a second detection unit are respectively arranged on the opposite sides, thus forming a dual-view cross-imaging system. During the data acquisition phase, the cold cathode X-ray sources on the left and right sides are synchronously or according to a preset timing sequence to emit X-ray beams onto the object being inspected located in the transmission channel.

[0073] For the acquisition of detection signals on each side, the system does not rely on rapid voltage switching from the X-ray source. Instead, it utilizes the internal physical structure of the detection unit to achieve energy spectrum separation. When the mixed-energy X-ray beam, after penetrating the object under inspection, reaches the detection unit, it first enters the low-energy detector (usually a thin scintillation crystal layer) located at the frontmost layer. The low-energy detector has high absorption efficiency for the low-energy long-wavelength components in the X-ray spectrum, converting low-energy photons into visible light and outputting a low-energy signal, while allowing most of the high-energy short-wavelength components to penetrate.

[0074] After passing through the low-energy detector, the X-ray beam then enters a filter (such as a copper or aluminum sheet) located in the middle layer. This filter, acting as a high-pass filter, further absorbs the remaining low-energy components of the beam, hardening its energy spectrum so that the rays penetrating the filter consist primarily of high-energy photons. Finally, the hardened high-energy beam is incident on a high-energy detector located in the rear layer (typically a thicker scintillation crystal layer). The high-energy detector intercepts and absorbs these highly penetrating photons, converting them into a high-energy signal. Through this layered interception method, within a single exposure cycle, both the transmission enhancement signal (high energy) reflecting the object's density and the material absorption signal (low energy) reflecting the object's atomic number can be simultaneously obtained from the same geometric path.

[0075] In this embodiment, through dual-view imaging from both the left and right sides, the system can observe the inspected object from different projection angles, effectively eliminating blind spots caused by the single angle of object placement or mutual obstruction. Secondly, the single-source dual-energy acquisition technology achieved by physical layering of the detector, compared with traditional voltage-switched dual-energy imaging, eliminates the need for high-frequency voltage modulation of the cold cathode X-ray source, reducing the complexity of the power supply system and hardware costs. At the same time, since the high-energy signal and the low-energy signal are acquired at the same time and at the same location, the high-low energy image registration error (motion artifact) caused by the movement of the inspected object is fundamentally avoided, providing a strictly aligned data foundation for subsequent high-precision R-value calculation and material property identification.

[0076] In one embodiment, the step of generating the X-ray image is followed by:

[0077] The time point at which the object under test triggers the position sensor on the transmission unit is monitored, and the time difference ΔT between the object under test passing through the cold cathode X-ray sources on the left and right sides is calculated in combination with the transmission speed.

[0078] Based on the time difference ΔT, the first image data and the second image data collected by the detection units on the left and right sides are aligned and registered in the spatial domain.

[0079] For the overlapping area of ​​the inspected object, the first R value in the first image data and the second R value in the second image data are calculated respectively, and the corrected material property R value is calculated according to the preset rules.

[0080] Specifically, the R-value refers to the ratio of the logarithmic attenuation rate of the inspected object to that of high-energy X-rays to that of low-energy X-rays. Since X-rays decay exponentially when penetrating matter, after acquiring the high-energy signal from the high-energy detector and the low-energy signal from the low-energy detector, logarithmic operations are first performed on these two signals to calculate the logarithmic attenuation values ​​for high and low energy. Subsequently, the ratio of the low-energy logarithmic attenuation value to the high-energy logarithmic attenuation value is calculated to obtain the R-value.

[0081] In this embodiment, firstly, the time point at which the front end of the object under inspection triggers the position sensor set on the transmission unit is monitored in real time and marked as time zero. The physical distance parameters of the left and right cold cathode X-ray sources in the transmission direction are read, and combined with the real-time monitored transmission speed, the time difference ΔT required for the object under inspection to move from passing through the first imaging area to passing through the second imaging area is calculated using kinematic formulas.

[0082] Based on the calculated time difference ΔT, the first and second image data collected by the detection units on the left and right sides are spatially aligned and registered. Specifically, the system uses the first image data as a spatial reference, calculates the pixel displacement based on the product of the transmission speed and the time difference ΔT, and compensates for the translation of the second image data on the time axis, so that the pixels representing the same physical part of the inspected object in the two images precisely coincide in the coordinate system.

[0083] After image registration is completed, the first R value is calculated from the high and low energy signals of the first image data, and the second R value is calculated from the high and low energy signals of the second image data. For the overlapping area of ​​the inspected object (i.e., the part of the object covered by both views), a preset rule is applied to calculate the corrected material property R value.

[0084] In this embodiment, through precise image registration based on the time difference ΔT, the system successfully unified physical data collected at different times into the same spatial coordinate system, providing a prerequisite for data fusion. More importantly, by calculating the final R value through preset rules, this method effectively solves the problem of R value calculation deviation caused by mutual occlusion of objects (such as a metal cup occluding organic matter) under a single viewpoint. The system can achieve the elimination of false positives and true negatives in the material properties of overlapping areas, significantly reducing the false alarm rate and false negative rate caused by occlusion.

[0085] In one embodiment, the step of calculating a first R value in the first image data and a second R value in the second image data for the overlapping region of the inspected object, and calculating a corrected R value for characterizing the material properties according to a preset rule, specifically includes:

[0086] Obtain the preset R-IL relationship curve for the material sample;

[0087] Multiple high- and low-energy transmission signal points in the corresponding overlapping regions of the first image data and the second image data are selected respectively;

[0088] Calculate the correlation coefficient between the data distribution of the transmitted signal points and the fitting curve of the R-IL relationship of the material sample;

[0089] By comparing the fitting correlation coefficients of the first image data and the second image data respectively, the R value corresponding to the image data with the larger fitting correlation coefficient is selected as the basis for judging the material properties.

[0090] Specifically, during the system calibration phase of the security scanner, R-IL relationship curves for material samples are pre-constructed and stored. These R-IL relationship curves are generated by fitting transmission data of standard stepped samples of different thicknesses (including organic, inorganic, and mixed samples) under irradiation with a cold cathode X-ray source. They reflect the nonlinear functional relationship between the ratio of high to low energy signals (R value) and the intensity of low energy signals (IL, characterizing the thickness or attenuation of the object).

[0091] In actual security checks, when the system identifies an overlapping area between the first and second image data, it does not directly use a single-point calculation method. Instead, it performs a multi-point distribution fitting step. Multiple pixels within the overlapping areas of the first and second image data are selected to combine high and low energy transmission signals, forming the first and second measured data sequences. These two measured data sequences are then projected onto a pre-defined R-IL relationship curve coordinate system for the material sample. The least squares method or Pearson correlation coefficient algorithm is used to calculate the fitting correlation coefficient between the measured data distribution and the standard curve.

[0092] The two calculated correlation coefficients are compared numerically. If the correlation coefficient corresponding to the first image data is greater than that corresponding to the second image data, it indicates that the attenuation characteristics of X-rays penetrating the overlapping area under the first viewpoint are more consistent with the physical laws of a single substance (i.e., less interference from debris); conversely, it indicates that the second viewpoint is superior. Finally, the R value calculated from the image data with the larger correlation coefficient is selected as the final basis for determining the material properties of the overlapping area, and the area is rendered as the corresponding pseudo-color on the display terminal accordingly.

[0093] Furthermore, in one embodiment, the preset rule employs a weighted algorithm to calculate a first R value from the high- and low-energy signals of the first image data, and a second R value from the high- and low-energy signals of the second image data. Subsequently, a weighted fusion calculation is performed on these two R values.

[0094] Specifically, weighting coefficients can be set based on the intensity and signal-to-noise ratio of the transmitted signal: if a high-density metal blockage in the transmission path of a certain viewpoint causes the signal to be too weak, the system automatically reduces the weight of the R value on that side, while increasing the weight of the R value on the other viewpoint. The first R value and the second R value are weighted and averaged or selected based on the weighting coefficients to obtain the corrected material property R value, which is then used as the final basis for determining the material category.

[0095] In this embodiment, a substance identification method based on R-IL curve fitting goodness of fit effectively solves the problem of misjudging substance properties caused by random stacking of objects in security inspection images. Traditional dual-energy algorithms often rely solely on the R value of a single pixel for table lookup. When objects are occluded or have overlapping edges, the R value is prone to drift (e.g., misjudging overlapping organic matter as inorganic matter). By comparing the fit between the data distribution from two perspectives and the standard physical model, a selection process is performed. This significantly improves the system's accuracy in automatically identifying key contraband such as explosives and drugs in complex and cluttered luggage scenarios, and reduces the false alarm rate.

[0096] In one embodiment, the R-IL relationship curve of the material sample is constructed by fitting the transmission data of the stepped sample under the irradiation of the cold cathode X-ray source; the R-IL relationship curve of the material sample includes organic material curves, inorganic material curves and mixture curves;

[0097] The step of calculating the correlation coefficient between the data distribution of the transmission signal points and the fitting curve of the R-IL relationship of the material sample includes:

[0098] Calculate the correlation coefficients between the data distribution of the transmission signal points and the fitting curves of organic matter, inorganic matter, and mixture, respectively;

[0099] The material category corresponding to the calculated maximum correlation coefficient is determined as the material property of the tested object.

[0100] Specifically, during the system calibration phase before the security scanner is put into use, a set of standardized stepped samples are scanned and acquired using a cold cathode X-ray source. These stepped samples are typically made of polyoxymethylene (representing organic matter), aluminum (representing mixtures), and steel (representing inorganic matter) of varying thicknesses. The detection unit acquires high-energy and low-energy signals from these stepped samples at different thicknesses, calculating the corresponding R-value (logarithmic ratio of high to low energy) and IL-value (low-energy signal intensity, characterizing attenuation). Numerical analysis algorithms are used to perform curve fitting on the acquired discrete data points, constructing three benchmark curves: an organic matter curve representing the R-value variation with thickness, an inorganic matter curve representing the R-value variation with thickness, and a mixture curve representing the R-value variation with thickness. These three curves together constitute the R-IL relationship curve of the material sample and are stored in the system's database.

[0101] In actual security checks, a curve-matching-based recognition step is performed on the region of interest (especially the overlapping region mentioned in the previous embodiments) in the image of the object being inspected. The system does not rely solely on the isolated value of a single pixel, but rather selects a set of continuous high- and low-energy transmission signal points within the region of interest, forming a set of measured data distributions. Subsequently, three fitting operations are performed in parallel: first, the correlation coefficient between the measured data distribution and the organic curve is calculated; second, the correlation coefficient between the measured data distribution and the inorganic curve is calculated; and third, the correlation coefficient between the measured data distribution and the mixture curve is calculated. The correlation coefficients (e.g., using Pearson correlation coefficient or coefficient of determination R²) quantify the similarity between the trend of the measured data and the standard physical model.

[0102] Finally, the decision logic is executed, comparing the three calculated correlation coefficients and identifying the maximum value. The system determines the most likely substance category to which the measured data best fits the curve. For example, if the correlation coefficient with the inorganic curve is the highest, the object is classified as inorganic; if the correlation coefficient with the organic curve is the highest, it is classified as organic. The decision result is then output to guide the display terminal in applying appropriate pseudo-color processing to the affected area.

[0103] In this embodiment, curve fitting and trend matching are introduced to match the physical model using the overall distribution characteristics of a set of data. Since the slope and curvature of the R-value as a function of thickness (IL) for different materials are their inherent physical fingerprints, even in cases of weak signals or partial interference, as long as the overall trend of the data conforms to the curve characteristics of a certain type of material (i.e., the highest correlation coefficient), the system can make a correct classification judgment. This method effectively reduces the false alarm rate, making the material classification of security inspection images more accurate, consistent, and smooth.

[0104] Furthermore, in one embodiment, the method further includes:

[0105] The time point at which the object being inspected triggers the position sensor located on the transmission unit is monitored.

[0106] The physical distance between the position sensor and the cold cathode X-ray source on the same side is obtained, as well as the inherent response time of the cold cathode X-ray source from receiving the start command to actually emitting the beam;

[0107] Based on the real-time monitored transmission speed, the transmission time of the inspected object from the trigger position sensor to the imaging area is calculated.

[0108] The start-up delay time of the cold cathode X-ray source is determined based on the difference between the transmission time and the inherent response time.

[0109] After the start-up delay time has elapsed since the time point at which the position sensor is triggered by the object under inspection, the cold cathode X-ray source is controlled to start emitting beams.

[0110] Specifically, during the hardware calibration phase of the security inspection system, the inherent parameters of the system are acquired and stored in advance: first, the physical distance parameter L, which is the straight-line distance in the transmission direction from the center of the installation point of the position sensor on the transmission unit to the center of the imaging sector of the L-shaped detection unit on the same side; second, the inherent response time parameter T, which is the hardware delay time required from the cold cathode X-ray source and its driving circuit receiving the digital start command to the X-ray tube actually generating a stable X-ray beam.

[0111] During the security check process, such as Figure 3 As shown, the system scans the signal status of the position sensors on both sides in real time. The position sensor status combinations are defined as (same-side status, opposite-side status), where 0 represents no trigger and 1 represents trigger. When the object being inspected has not yet reached the same-side position sensor, the status of both sets of position sensors is determined to be (0, 0), and the system remains in standby mode. When the object being inspected moves with the conveyor unit and touches or obstructs the same-side position sensor, a status jump to (1, 0) is detected. At this point, the delay calculation program is immediately started, using the current moment as the reference point and combining it with the real-time monitored conveyor speed V.

[0112] To ensure precise synchronization between the X-ray beam exit time and the object's arrival time in the imaging area, a computational relationship is established based on kinematic principles. Considering the total distance L that the object moves from the sensor trigger to being effectively imaged, which consists of two parts: one is the distance V*N that the object moves during the countdown (i.e., delay time N), and the other is the distance V*T that the object moves during the cold cathode source's activation response (i.e., response time T). Therefore, these three satisfy the linear equation: VT + VN = L. By transforming and solving this equation, the activation delay time N required to open the cold cathode X-ray source is calculated using the following formula:

[0113]

[0114] In system design, to reduce computational complexity, the mechanical structures on both sides of the security scanner are typically designed to be perfectly symmetrical, assuming equal physical distances L on both sides, allowing the reuse of the same set of delay parameters. However, in practical engineering applications, if slight differences in installation positions on both sides or asymmetrical design requirements are considered, the activation delay time N is calculated independently for the left and right sides according to the formula above. After the calculated delay time N has elapsed since the triggering moment, an activation command is sent to the cold cathode X-ray source on the same side. After the inherent response time T, the X-ray beam is emitted precisely at the instant the object reaches the detection plane, achieving zero-error synchronous imaging.

[0115] In this embodiment, by explicitly defining the transition logic from sensor state (0,0) to (1,0), the system effectively prevents false triggering. More importantly, the introduced mathematical model compensates for the physical response hysteresis of the source component. This control strategy not only accommodates symmetrical or asymmetrical mechanical structure designs, exhibiting high engineering adaptability, but also ensures "immediate X-ray exposure," minimizing ineffective radiation dose while maintaining imaging integrity and enhancing radiation protection safety.

[0116] Furthermore, in one embodiment, a first gravity sensor and a second gravity sensor are respectively provided at both ends of the transmission unit; the method further includes:

[0117] Real-time monitoring of the trigger status of the first gravity sensor and the second gravity sensor;

[0118] If the first gravity sensor outputs a trigger signal and the second gravity sensor does not output a trigger signal, a forward running command is generated to control the transmission unit to run in the direction from the first gravity sensor to the second gravity sensor.

[0119] If the second gravity sensor outputs a trigger signal and the first gravity sensor does not output a trigger signal, a reverse operation command is generated to control the transmission unit to run in the direction from the second gravity sensor to the first gravity sensor.

[0120] Specifically, such as Figure 3 As shown, at the hardware architecture level, the conveyor unit is designed as a mechanical structure supporting bidirectional reversible transport. A first gravity sensor module and a second gravity sensor module are independently installed below the belts at the physical beginning (designated as the first end) and physical end (designated as the second end) of the conveyor unit, respectively. The controller collects the pressure signals output by the first and second gravity sensor modules in real time through independent data channels and compares them with a preset minimum trigger threshold to determine whether an object to be inspected is currently present.

[0121] When the system is in standby monitoring mode, it scans the signal status of the two sensors in parallel. When the pressure value output by the first gravity sensor exceeds the trigger threshold, a trigger signal is output. Simultaneously, if the second gravity sensor does not output a trigger signal (i.e., it is in an unloaded state), it is determined that the current security inspection requirement is to transport the object from the first end to the second end. At this time, a forward operation command is generated and sent to the frequency converter driver of the transmission unit. The drive motor rotates in the direction from the first gravity sensor to the second gravity sensor, automatically pulling the object to be inspected into the security inspection channel for scanning.

[0122] Conversely, when a trigger signal is detected from the second gravity sensor while the first gravity sensor does not, the security check requirement is determined to be a transfer from the second end to the first end. At this point, a reverse operation command is immediately generated, controlling the conveyor unit to run in the direction from the second gravity sensor to the first gravity sensor. If both sensors trigger simultaneously or neither triggers, the controller keeps the conveyor unit in a stopped or standby state until a clear single-sided trigger signal is detected. This control logic ensures that the security scanner can automatically respond based on the passenger's bag placement location without manual intervention to change the operating direction.

[0123] In this embodiment, by deploying gravity sensors at both ends of the conveying unit and cooperating with directional arbitration logic, the system enables the device to automatically identify and initiate the correct conveying process regardless of which side of the security scanner the operator or passenger is on. This eliminates the tedious step of frequently manually operating control panel buttons to switch motor directions, greatly improving security screening efficiency. Simultaneously, combined with idle stop logic, it achieves true on-demand operation, effectively reducing mechanical wear and power consumption, making it particularly suitable for applications such as subways and customs where passenger flow direction varies tidally.

[0124] Furthermore, in one embodiment, the method further includes a detector response inconsistency correction step before generating the X-ray image:

[0125] Acquiring background data of the detector under X-ray-free conditions. And calculate the baseline average. ;

[0126] Acquire no-load data from the detector while the X-ray source is on. And calculate the average value under no-load conditions. ;

[0127] According to the formula Calculate the correction factor for the nth detector unit. .

[0128] Specifically, because the detection unit contains hundreds or thousands of independent detection pixels, the sensitivity of each pixel to the same dose of X-rays is not entirely uniform due to manufacturing limitations. Direct imaging would result in vertical stripe noise in the image. Therefore, the following correction logic is performed before generating the X-ray image:

[0129] First, with the cold cathode X-ray source off and in an environment free from any external radiation interference, the system acquires the dark current signal from the detection units. The raw background data output by each detection unit is read and denoted as... And calculate the arithmetic mean of the background data of all detection units, denoted as the background mean. This step aims to obtain the detector's zero-point drift reference.

[0130] Secondly, with the transmission unit in idle operation (i.e., no object being inspected) and the cold cathode X-ray source turned on and in a stable beam output state, the system acquires the full-scale response signal of the detection unit. The raw idle data output by each detection unit is read and denoted as... And calculate the arithmetic mean of the no-load data of all detection units, denoted as the no-load average. This step aims to obtain a gain reference for the detector.

[0131] Finally, based on the collected data, the correction factor k[n] of the nth detection unit is calculated using the formula described above. The calculated correction factor k[n] is then stored in the correction coefficient table of the FPGA or DSP. In subsequent actual security scans, the real-time signal is normalized to output smooth image data.

[0132] In this embodiment, by introducing the background average and the idle average as global benchmarks, the sensitivity deviation (i.e., correction factor) of each pixel relative to the overall level can be accurately calculated. Processing the original signal using this factor not only completely eliminates vertical stripes and brightness unevenness in the image background, significantly improving the visual clarity of the image, but more importantly, it ensures that the signals output by different pixels have uniform dimensions and linearity. This provides high-precision raw data for subsequent calculation of the R-value based on the ratio of high and low energy signals, avoiding errors in material property identification caused by detector hardware errors.

[0133] Furthermore, in one embodiment, the step of generating the X-ray image includes correcting the acquired raw signal V[n] according to the following formula:

[0134]

[0135] in, This is the corrected output signal.

[0136] Specifically, during normal baggage scanning by the security scanner, each detection pixel in the detection unit outputs the original voltage signal, attenuated by the inspected object, in real time, denoted as... However, because the detector is not in an ideal linear response state, the original signal... The image contains dark current noise and gain errors caused by differences in pixel sensitivity. Therefore, before generating the final displayed X-ray image, the image processing unit must access the pre-calibrated background data stored in the memory unit. and the correction factor calculated in the foregoing embodiments. For the original signal Perform point-by-point calculations.

[0137] The specific correction logic follows the above formula, where n is the channel index number of the detection unit; The output signal after normalization correction is characterized, and this signal truly reflects the transmittance of the inspected object to X-rays. This represents the measured signal value output by the detection unit at the current scanning moment. This corresponds to the background bias value of the detection unit under no-light conditions; thus, a high signal-to-noise ratio X-ray image without fixed pattern noise is generated by stitching together the data.

[0138] In this embodiment, the correction method restores the strict linear mapping relationship between the detector output signal and the incident X-ray intensity by eliminating dark current and gain error. This linearity is the physical basis for dual-energy data analysis and equivalent atomic number inversion. By ensuring the accuracy of the input data, this application enables the subsequent calculation of the R value based on the ratio of high and low energy signals to be free from the interference of hardware performance fluctuations, thereby ensuring the stability of the determination of the material properties of the inspected object and effectively preventing false alarms or missed alarms of contraband caused by abnormal response of the detection unit.

[0139] Furthermore, in one embodiment, the formula for calculating the fitting correlation coefficient is:

[0140]

[0141] Where R represents the calculated fitting correlation coefficient, used to quantify the similarity between the distribution of the measured data and the distribution of the standard curve; n represents the total number of detection data involved in the calculation, that is, the number of sampling points selected in the overlapping area of ​​the image; i represents the index number of the data point, with a value ranging from 1 to n; This represents the i-th low-energy signal value actually acquired by the detection unit, which reflects the actual X-ray transmission intensity of the object under test at the i-th sampling position; This represents the arithmetic mean of the above n collected low-energy signal values; This represents the i-th simulated low-energy value obtained by substituting the corresponding coordinate parameters into the R-IL relationship curve of the material sample based on the current R-value assumption. It represents the standard signal intensity under the theoretical model. This represents the arithmetic mean of the above n simulated low-energy values.

[0142] Specifically, during the system calibration phase, data is first collected based on the stepped sample materials. These stepped sample materials include at least typical substances such as metals (representing inorganic materials) and liquids (representing organic materials). The system collects transmission data from these samples at different thicknesses and uses numerical analysis to fit a standard sample R-IL function. This R-IL function reflects the mapping relationship between the dual-energy R-value and the low-energy signal intensity (IL), serving as a benchmark model for subsequent comparisons.

[0143] During the scanning process of the security scanner, the X-ray detector acquires multiple high- and low-energy transmission signals of the object in real time. The detection unit acquires multiple sampling points within the region of interest (e.g., overlapping regions), recording the high-energy and low-energy transmission signals corresponding to each sampling point. Based on a preset dual-energy R-value algorithm, the R-value corresponding to the material is calculated using the acquired signals. Simultaneously, the current coordinate parameters are substituted into the sample R-IL relationship curve function obtained in the first step of fitting to calculate the simulated value that the point should present under the theoretical model. The measured data and simulated data of each point are then substituted into the fitting correlation coefficient formula. Specifically, the data from multiple sampling points are compared... The corresponding simulated values ​​are then substituted into the above formula for calculation.

[0144] Calculation of measured low-energy signals Low energy values ​​compared with theoretical simulations The Pearson correlation coefficient between the two is used to determine whether the distribution trend of the measured data conforms to the R-IL function characteristics of a specific substance (such as metal or liquid), thereby determining the material properties of the tested object.

[0145] In this embodiment, by introducing the ratio of covariance to standard deviation, the system no longer relies solely on the absolute amplitude of the signal when determining the substance, but instead focuses on the waveform trend of data changes. This algorithmic characteristic gives the system extremely strong anti-interference capabilities: even if the detector is affected by temperature drift causing a shift in the overall signal baseline, or if there are slight fluctuations in the X-ray source energy, as long as the relative trend of the measured data remains consistent with the physical model, the calculated correlation coefficient R can still remain stable. This effectively avoids misjudgment of substance properties caused by hardware parameter drift, ensuring the accuracy of identifying difficult targets such as overlapping luggage and thin explosive devices.

[0146] Furthermore, in one embodiment, the step of calculating the first R value and the second R value includes:

[0147] Obtain the transmission intensity of high-energy X-rays before they enter the object being inspected. and the transmission intensity of low-energy X-rays before they enter the object being inspected. ;

[0148] Obtain the transmission intensity of high-energy X-rays after they have passed through the object under inspection. And the transmission intensity of low-energy X-rays after passing through the object being inspected. ;

[0149] The R value is calculated using the following formula:

[0150] in, and These represent the mass absorption coefficients of high-energy X-rays and low-energy X-rays as they pass through the object under inspection, respectively.

[0151] Specifically, in security inspection imaging, equivalent atomic number identification is the core basis for distinguishing substances with different properties (such as organic matter, inorganic matter, and mixtures). In order to obtain accurate atomic number information, the system needs to calculate the characteristic value, namely the R value, which is unaffected by the thickness and physical state of the object.

[0152] First, during the initialization phase of each scan cycle or during idle intervals, the system controls the detection unit to acquire air calibration data that is not obstructed by any object. The signal received by the detector at this time is the incident intensity, denoted as the high-energy X-ray incident intensity. and low-energy X-ray incident intensity When the object being inspected enters the imaging area, the detection unit collects the attenuation signal after penetrating the object, which is recorded as the high-energy X-ray transmission intensity and the low-energy X-ray transmission intensity, respectively.

[0153] Then, the ratio of the logarithmic decay rate of low-energy rays to the logarithmic decay rate of high-energy rays is calculated using the above formula. According to the physical laws governing the interaction between X-rays and matter, this ratio is theoretically equivalent to the mass absorption coefficient of the matter for low-energy rays. and The ratio of mass absorption coefficients. Since the ratio directly depends on the effective atomic number (Zeff) of the substance and is independent of the substance's density, thickness, or aggregation state (solid, liquid, etc.), the calculated R value can serve as a unique "fingerprint" feature for substance classification. Based on the calculated R value, the substance type is determined by referring to a table, and the display module is driven to perform corresponding pseudo-color processing (e.g., smaller R values ​​are displayed as orange organic substances, and larger R values ​​are displayed as blue inorganic substances).

[0154] It is worth noting that, considering that in practical industrial applications, cold cathode X-ray sources emit continuous-spectrum X-rays with continuously varying wavelengths, the mass absorption coefficient is not a strictly constant but decreases with increasing photon energy (i.e., there is a beam hardening effect). Therefore, the R value calculated in this embodiment is usually used as a primary feature value, and can be further combined with the "R-IL fitting curve" in the aforementioned embodiment for second-order correction to obtain more accurate identification results.

[0155] In this embodiment, by introducing the logarithmic ratio of incident intensity to transmitted intensity, the R value calculated by the system will theoretically be consistent as long as the chemical components (atomic numbers) to be detected are the same. This enables accurate differentiation of contraband concealed under external camouflage, such as identifying hidden drugs or explosives from a thick pile of clothing, greatly improving the accuracy and reliability of security screening.

[0156] Furthermore, in one embodiment, after determining the material properties of the inspected object, a pseudo-color mapping step is also included:

[0157] A pre-defined mapping table between material properties and colors;

[0158] If the substance is determined to be organic, the corresponding area in the image will be mapped to the first preset color;

[0159] If the substance is determined to be inorganic, the corresponding area in the image will be mapped to the second preset color.

[0160] If the material is determined to be a mixture, the corresponding area in the image will be mapped to the third preset color;

[0161] The final pseudo-color X-ray image is generated based on the mapped colors and corrected signal strength.

[0162] Specifically, a mapping table (i.e., a color lookup table, LUT) between material properties and colors is pre-built and stored. This mapping table can be set according to common standards in the security inspection industry: substances with lower atomic numbers and smaller R values ​​are defined as organic substances and assigned a first preset color (usually orange); substances with higher atomic numbers and larger R values ​​are defined as inorganic substances and assigned a second preset color (usually blue); substances with atomic numbers and R values ​​between the two are defined as mixtures and assigned a third preset color (usually green).

[0163] In the specific processing flow of image generation, every pixel or segmented object region of the entire X-ray image is traversed. If the material property of a certain region is determined to be organic (such as food, plastic, explosives) based on the R value calculated or the fitting result of the aforementioned embodiment, the system retrieves the first preset color as the base color of the region; if it is determined to be inorganic (such as ironware, copper wire, firearms), the system retrieves the second preset color as the base color; if it is determined to be a mixture (such as aluminum products, glass), the system retrieves the third preset color as the base color.

[0164] After determining the primary color, the pixel brightness is further determined by combining the signal strength (i.e., the corrected high-energy or low-energy signal amplitude) processed in the aforementioned correction steps. A stronger signal strength indicates a thinner or lower-density object, resulting in higher pixel brightness; a weaker signal strength indicates a thicker or higher-density object, resulting in lower pixel brightness. The selected primary color and the calculated brightness are then fused and rendered to generate a pseudo-color X-ray image containing rich material and internal structural information, which is then presented to security personnel via a display terminal.

[0165] In this embodiment, the pseudo-color mapping image generation method greatly improves the intuitiveness and efficiency of security inspection image processing. It helps security personnel instantly distinguish between items of completely different natures, shortens the inspection time for a single piece of luggage, and significantly increases the detection rate of specific categories of prohibited items.

[0166] The steps of the various methods described above are only for clarity. In practice, they can be combined into one step or some steps can be split into multiple steps. As long as they include the same logical relationship, they are all within the scope of protection of this application. Adding insignificant modifications or introducing insignificant designs to the algorithm or process, but without changing the core design of the algorithm and process, are also within the scope of protection of this application.

[0167] Figure 4 A schematic diagram of the architecture of a cold cathode X-ray baggage security scanner provided for some embodiments of this application includes:

[0168] The conveying unit 1 is used to convey the object to be inspected, and the conveying unit is equipped with a gravity sensor and a position sensor.

[0169] Size detection unit 2 is disposed above or to the side of the conveying unit and is used to detect the external dimensions of the object being inspected.

[0170] The cold cathode X-ray source 3 includes a cold cathode X-ray tube, a positive high voltage circuit, and a negative secondary high voltage circuit; the positive high voltage circuit is configured to control the high voltage output time by adjusting the duty cycle, and the negative secondary high voltage circuit is configured to control the electron beam current by adjusting the voltage amplitude.

[0171] Detection unit 4 includes a high-energy detector and a low-energy detector, used to collect X-ray transmission signals;

[0172] Control unit 5 is communicatively connected to the transmission unit 1, size detection unit 2, cold cathode X-ray source 3, and detection unit 4;

[0173] The control unit 5 is configured to perform the control method for the cold cathode X-ray baggage scanner as described in any of the above.

[0174] Specifically, such as Figure 5As shown, the core physical carrier of the security inspection device is the conveyor unit, which is used to carry and transport various bags or goods to be inspected. The gravity sensor of the conveyor unit is responsible for monitoring whether there is an object load at the feeding end, while the position sensor is used to accurately capture the arrival time of the leading edge and the departure time of the trailing edge of the object being inspected, providing physical trigger signals for the timing control of the system.

[0175] A dimension detection unit (such as an infrared light curtain array or a 3D vision camera) is integrated on the front side of the entrance to the conveyor channel, that is, on the support above or to the side of the conveyor unit. The dimension detection unit is configured to scan the external contour of the object non-contactly before the object enters the X-ray imaging area, acquire the length, width and height data of the object in real time, and send these geometric parameters to the control unit.

[0176] The core components of the security scanner's radiation imaging system are the cold cathode X-ray source and the detection unit. The cold cathode X-ray source abandons the traditional filament heating structure and adopts a cold cathode X-ray tube based on the field emission principle. The accompanying drive circuit includes independent positive high-voltage and negative secondary high-voltage circuits. The positive high-voltage circuit is designed in pulse modulation output mode, precisely controlling the loading duration of the anode high voltage through microsecond-level duty cycle adjustment logic, thereby determining the time window for a single exposure. The negative secondary high-voltage circuit is designed in amplitude-adjustable output mode, linearly controlling the electric field strength on the cathode surface by changing the amplitude of the negative voltage applied to the grid, thus controlling the magnitude of the emitted electron beam. The detection unit is located on the opposite side of the X-ray source and includes a high-energy detector array and a low-energy detector array, used to simultaneously acquire high-energy and low-energy X-ray transmission signals after penetrating the inspected object.

[0177] The control unit, serving as the computational and scheduling center of the entire machine, establishes bidirectional communication connections with the transmission unit, dimensional detection unit, cold cathode X-ray source, and detection unit via an industrial bus. The control unit internally stores an execution program configured to coordinate the various components to perform the control method described in any of the aforementioned embodiments based on sensor feedback signals and dimensional data, then process the X-ray images and display them on a display device.

[0178] In this embodiment, the cold cathode X-ray baggage scanner fully utilizes the potential of the cold cathode source by employing a strategy of separating the positive high-voltage duty cycle and the negative secondary high-voltage amplitude control. Duty cycle adjustment enables nanosecond-level rapid exposure control, eliminating motion blur; amplitude adjustment achieves dynamic matching of beam intensity, automatically adapting the optimal dose based on object size and avoiding energy waste. Secondly, the integration of a size detection unit and a bidirectional transmission mechanism gives the device adaptive adjustment capabilities, automatically adjusting its operating strategy according to object size and supporting bidirectional blind operation, greatly improving the throughput and intelligence level of the security checkpoint. Finally, through the overall scheduling of the control unit, the entire machine seamlessly integrates sensor data from the physical layer with image processing logic from the algorithm layer, ensuring high-definition output images and high accuracy in material identification.

[0179] In one embodiment, the size detection unit is one of a light curtain sensor, a 3D depth camera, or a lidar.

[0180] The detection unit is an L-shaped detection unit, which includes a high-energy detector, a filter, and a low-energy detector; the low-energy detector, the filter, and the high-energy detector are stacked sequentially along the X-ray incident direction.

[0181] Specifically, for the size detection unit, designers can choose from three non-contact ranging devices—light curtain sensors, 3D depth cameras, or LiDAR—based on the specific requirements of the actual application scenario regarding detection accuracy and cost budget. If light curtain sensors are selected, they are installed in pairs on both sides of the conveyor channel, and the object size is inferred by calculating the number of blocked light beams. If 3D depth cameras or LiDAR are selected, they are installed on the top bracket of the conveyor channel, and high-precision three-dimensional point cloud data of the inspected object is obtained using the time-of-flight (ToF) method or structured light technology.

[0182] For the detection unit, this embodiment adopts an L-shaped detection unit layout, that is, the detector modules are arranged in a right-angled "L" shape along one side and bottom of the transmission channel, thereby forming an all-round detection field of view covering the cross-section of the object being inspected. In terms of microscopic pixel structure, each detection channel adopts a dual-energy stacked structure. Along the incident direction of X-rays emitted from the cold cathode X-ray source, a low-energy detector, a filter, and a high-energy detector are arranged sequentially. Among them, the low-energy detector is located at the front end and is configured to preferentially absorb and respond to low-energy soft X-rays; the filter (usually made of copper or intermediate atomic number metals) is located in the middle and is configured to filter out residual low-energy rays to achieve energy spectrum hardening; the high-energy detector is located at the rear end and is configured to receive and respond to high-energy hard X-rays with strong penetrating power.

[0183] In this embodiment, the diverse selection of size detection units allows the equipment to flexibly adapt to different inspection needs, ranging from ordinary express parcels to high-precision electronic products. Simultaneously, the L-shaped arrangement of the detection units eliminates the imaging blind spots at the bottom corners of the rectangular channel, ensuring complete scanning even when the object being inspected is placed close to the channel edge. Most importantly, the use of a stacked structure with a low-energy detector in front, a high-energy detector behind, and an intermediate filter utilizes physical filtering principles to achieve efficient spatial separation of the high and low energy X-ray spectra. This structure not only ensures strict alignment of high-energy and low-energy data in terms of sampling time and spatial position but also significantly improves the signal-to-noise ratio and separation of the dual-energy data, providing a high-quality raw signal foundation for subsequent accurate calculation of R-values ​​and material property identification. Furthermore, in one embodiment, the security inspection device also includes:

[0184] The transmission unit has a first end and a second end, which are used to carry and transport the object to be inspected.

[0185] The transmission unit of the security scanner also includes a bidirectional motor;

[0186] The first sensing component and the second sensing component are respectively disposed at the first end of the transmission unit and the second end of the transmission unit.

[0187] The cold cathode X-ray source includes a first cold cathode X-ray source and a second cold cathode X-ray source, which are arranged at intervals or side by side along the transport path of the transport unit; the first cold cathode X-ray source is configured to emit X-rays at the object under inspection from a first angle, and the second cold cathode X-ray source is configured to emit X-rays at the object under inspection from a second angle.

[0188] The detection unit includes a first detection unit and a second detection unit, which are arranged in a counter-firing configuration with the first cold cathode X-ray source and the second cold cathode X-ray source, respectively. The first detection unit is used to collect the transmission signal after the first cold cathode X-ray source penetrates the object under test, and the second detection unit is used to collect the transmission signal after the second cold cathode X-ray source penetrates the object under test.

[0189] The control unit is communicatively connected to the transmission unit, the first sensing component, the second sensing component, the first cold cathode X-ray source, the second cold cathode X-ray source, the first detection unit, and the second detection unit, respectively.

[0190] Specifically, the conveyor unit of the security scanner has a first end (e.g., the left entrance) and a second end (e.g., the right entrance) with physical opposite positions. To achieve automatic sensing of the feeding action, a first sensing component is integrated under the conveyor belt at the first end, and a second sensing component is integrated under the conveyor belt at the second end. Both the first and second sensing components are combinations of gravity sensors and photoelectric position sensors, capable of simultaneously detecting the load weight and object position. The drive mechanism of the conveyor unit uses a bidirectional motor capable of responding to forward and reverse commands. Together with the first and second sensing components installed under the conveyor belt or at both ends of the frame, they constitute an intelligent sensing conveyor system capable of automatically identifying the object to be inspected and initiating the correct conveying process.

[0191] The security scanner employs a dual-source, dual-detector 3D scanning architecture. The first cold cathode X-ray source is installed at the top of the conveyor channel, projecting its beam vertically downwards to form a top-view angle. A corresponding first detection unit is located at the bottom of the conveyor channel to collect transmission data from the first cold cathode X-ray source. The second cold cathode X-ray source can be installed on the side of the conveyor channel or at the top, a distance away from the first cold cathode X-ray source. A corresponding second detection unit is positioned opposite it to collect transmission data from the second cold cathode X-ray source. The first and second cold cathode X-ray sources maintain a preset physical distance along the conveying direction to avoid X-ray scattering interference.

[0192] The control unit, serving as the system's logical center, is independently connected to the two sets of light sources, two sets of detectors, and two sets of sensors. When the object being inspected triggers the sensing component at either end, the control unit drives the transmission unit to operate and, based on the object's real-time position within the channel, sequentially or synchronously triggers the first and second cold cathode X-ray sources to emit beams. The system ultimately transmits the images acquired by the first and second detection units to the display terminal for split or fused display on the same screen.

[0193] In this embodiment, the dual-view imaging of a first cold cathode X-ray source and a second cold cathode X-ray source significantly improves the detection rate of contraband. Simultaneously, by installing sensing components at both ends of the transmission unit, coupled with bidirectional control logic, the limitation of traditional security scanners that only allow unidirectional bag entry is broken. This enables the equipment to adapt to various complex on-site security inspection flow requirements, achieving efficient and blind-spot-free intelligent security inspection operations.

[0194] Furthermore, in one embodiment, the security inspection device also includes an uninterruptible power supply (UPS), which is electrically connected to the cold cathode X-ray source and the controller.

[0195] The uninterruptible power supply (UPS) monitors the power supply status of the external mains.

[0196] When an external mains power interruption is detected, the system switches to the uninterruptible power supply (UPS) mode and sends a power outage trigger signal to the controller.

[0197] In response to the power failure trigger signal, the controller cuts off the output of the negative high voltage circuit and the positive high voltage circuit of the cold cathode X-ray source.

[0198] Write the cached X-ray image data into non-volatile memory; after data storage is completed, control the security scanner to execute the system shutdown procedure.

[0199] Specifically, such as Figure 6 As shown in the hardware connection diagram, the cold cathode X-ray baggage scanner is equipped with an uninterruptible power supply (UPS). The UPS is connected in series between the external AC power input and the internal load of the equipment, and establishes power supply and signal communication connections with the cold cathode X-ray source and the controller, respectively.

[0200] During normal operation of the security scanner, the uninterruptible power supply (UPS) continuously monitors the power supply voltage and frequency of the external mains. Once an unexpected interruption of the external mains power or a voltage drop below the operating threshold is detected, the UPS automatically switches to the internal battery inverter power supply mode within milliseconds to maintain the instantaneous operational stability of the system and simultaneously sends a high-priority power failure trigger signal to the controller.

[0201] Upon receiving a power failure trigger signal, the controller immediately initiates an emergency shutdown sequence. First, to ensure radiation safety and reduce power consumption, the controller immediately cuts off the positive high-voltage circuit output and the negative secondary high-voltage circuit output of the cold cathode X-ray source, causing the X-ray tube to immediately cease radiation generation. Next, the controller executes data protection steps, quickly writing unarchived X-ray image data temporarily stored in volatile buffer (RAM) and the current system status log to non-volatile memory such as hard disk or flash memory to prevent the loss of critical security inspection data. After confirming that all data write operations are complete, the controller sends a shutdown command to the operating system, controlling the security scanner to execute standard file system unloading and soft shutdown procedures until the system completely stops operating.

[0202] The UPS power failure protection mechanism provided in this embodiment offers dual safety assurance for sophisticated security inspection equipment. On one hand, for expensive cold cathode X-ray sources, actively cutting off the high-voltage and sub-high-voltage outputs at the moment of power failure effectively avoids hardware shocks or insulation damage caused by power fluctuations, extending the lifespan of core components. On the other hand, for security inspection operations, the emergency data transfer logic ensures that even in the event of a sudden power outage, images of luggage currently being inspected can be completely saved and traced, eliminating the risk of data loss. Simultaneously, the execution of a standardized soft shutdown procedure prevents file system corruption or operating system crashes, ensuring that the equipment can quickly resume normal operation after power is restored.

[0203] The control unit in the above embodiments can be various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, etc. The control unit can also be various forms of mobile devices, such as cellular phones, smartphones, wearable devices, and other similar computing devices.

[0204] The control unit includes: one or more processors; and a memory storing computer program instructions that, when executed, cause the processors to perform the steps of the methods provided in any one or more of the above embodiments. Figure 7 An exemplary structural diagram of the control unit is disclosed. The control unit includes one or more processors 1101, a memory 1102, and interfaces for connecting the various components, including high-speed interfaces and low-speed interfaces. The various components are interconnected via different buses and can be mounted on a common motherboard or otherwise installed as needed. The processors can process instructions executed within the control unit, including instructions stored in or on memory to display graphical information of a GUI on an external input / output device (such as a display device coupled to the interface). In some other embodiments, multiple processors and / or multiple buses can be used with multiple memories and multiple memory modules, if desired. Similarly, multiple control units can be connected to provide some necessary operations for each device. The components, their connections and relationships, and their functions shown herein are merely examples and are not intended to limit the implementation of the present application described and / or claimed herein.

[0205] The control unit may further include an input device 1103 and an output device 1104. The processor 1101, memory 1102, input device 1103 and output device 1104 may be connected by a bus or other means, as shown in the figure, which is connected by a bus.

[0206] Input device 1103 can receive input numerical or character information, and generate key signal inputs related to user settings and function control of the control unit, such as a touch screen, keypad, mouse, trackpad, touchpad, pointer, one or more mouse buttons, trackball, joystick, etc. Output device 1104 may include a display device, auxiliary lighting device (e.g., LED), and haptic feedback device (e.g., vibration motor). The display device may include, but is not limited to, a liquid crystal display, a light-emitting diode display, and a plasma display. In some embodiments, the display device may be a touch screen.

[0207] To provide interaction with the user, the control unit can be a computer. The computer has: a display device (e.g., a cathode ray tube or LCD monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse) through which the user provides input to the computer. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback); and input from the user can be received in any form (e.g., voice input or tactile input).

[0208] In this embodiment, a computer-readable medium stores a computer program / instructions that, when executed by a processor, implement the steps of the methods provided in any one or more of the above embodiments. This computer-readable medium may be included in the control unit described in the above embodiments; or it may exist independently and not assembled into the device. The computer-readable medium carries one or more computer-readable instructions.

[0209] The memory 1102 can serve as a non-transitory computer-readable storage medium, used to store non-transitory software programs, non-transitory computer-executable programs, and modules. The processor 1101 executes various functional applications and data processing of the server by running the non-transitory software programs, instructions, and modules stored in the memory 1102, thereby implementing the program instructions / modules corresponding to the methods provided in any one or more of the embodiments described above in this application.

[0210] The memory 1102 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the control unit. Furthermore, the memory 1102 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, the memory 1102 may optionally include memory remotely located relative to the processor 1101, and these remote memories may be connected to the control unit via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0211] It should be noted that the computer-readable medium described in this application can be a computer-readable signal medium or a computer-readable storage medium, or any combination thereof. Computer-readable media can be, for example, but not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to, electrical connections having one or more wires, portable computer disks, hard disks, random access memory, read-only memory, erasable programmable read-only memory, optical fibers, portable compact disk read-only memory, optical storage devices, magnetic storage devices, or any suitable combination thereof. In this application, a computer-readable medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0212] Computer-readable media include permanent and non-permanent, removable and non-removable media, which can store information by any method or technology. Information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase-change memory, static random access memory, dynamic random access memory, other types of random access memory, read-only memory, electrically erasable programmable read-only memory, flash memory or other memory technologies, read-only optical discs, digital versatile optical discs or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transfer medium that can be used to store information accessible by a computing device.

[0213] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, and conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including local area networks (LANs) or wide area networks (WANs), or it can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0214] In the above embodiments, all or part of the implementation can be achieved through software, hardware, firmware, or any combination thereof. For example, it can be implemented using an application-specific integrated circuit (ASIC), a general-purpose computer, or any other similar hardware device. In some embodiments, the software program of this application can be executed by a processor to implement the above steps or functions. Similarly, the software program of this application (including related data structures) can be stored in a computer-readable recording medium, such as RAM memory, magnetic or optical drives, floppy disks, and similar devices. In addition, some steps or functions of this application can be implemented in hardware, for example, as circuitry that cooperates with a processor to perform the various steps or functions.

[0215] The computer program product provided in this application includes one or more computer programs / instructions. When executed by a processor, these computer programs / instructions generate, in whole or in part, the processes or functions described in this application. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium may be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state drive), etc.

[0216] The flowcharts or block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of devices, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented using a dedicated hardware-specific system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0217] The scope of this application is defined by the appended claims rather than the foregoing description, and is therefore intended to encompass all variations falling within the meaning and scope of equivalents of the claims. No reference numerals in the claims should be construed as limiting the scope of the claims. Furthermore, it is clear that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. Multiple units or devices recited in a device claim may also be implemented by a single unit or device in software or hardware. Terms such as "first," "second," etc., are used only for distinguishing descriptions and do not indicate any particular order, nor should they be construed as indicating or implying relative importance.

[0218] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily made by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims, and the above embodiments should be regarded as exemplary and non-limiting.

Claims

1. A control method of a cold cathode X-ray baggage inspection apparatus, characterized by, The security scanner includes a cold cathode X-ray source and a transmission unit; the cold cathode X-ray source includes a positive high-voltage circuit for controlling the high-voltage output time and a negative secondary high-voltage circuit for controlling the electron beam current magnitude; the method includes: The load data and external dimensions of the object under inspection are acquired, and the transmission speed of the transmission unit is monitored in real time. Based on the load data and the external dimensions data, the equivalent density parameter of the inspected object is calculated; Based on the equivalent density parameter, the basic operating parameters of the cold cathode X-ray source are determined; the amplitude of the negative secondary high voltage in the negative secondary high voltage circuit is adjusted to match the electron beam intensity corresponding to the equivalent density parameter; at the same time, the output amplitude of the positive high voltage circuit is adjusted to obtain the X-ray penetration power corresponding to the equivalent density parameter. Based on the transmission speed, dynamic exposure compensation is performed on the cold cathode X-ray source; the duty cycle of the positive high voltage output is adjusted in real time in the positive high voltage circuit so that the duty cycle and the transmission speed maintain a preset proportional relationship; During the beam output of the cold cathode X-ray source based on the duty cycle, high-energy and low-energy signals passing through the object under inspection are acquired, and an X-ray image is generated.

2. The control method of a cold cathode X-ray baggage inspection apparatus according to claim 1, characterized by, The cold cathode X-ray source is dynamically exposed according to the transmission speed; The step of adjusting the duty cycle of the positive high voltage output in real time in the positive high voltage circuit to maintain a preset proportional relationship between the duty cycle and the transmission speed specifically includes: Set the standard transmission speed and the corresponding standard duty cycle; Real-time acquisition of the current actual transmission speed; The real-time duty cycle of the positive high voltage output is adjusted according to a preset compensation logic; wherein, when the actual transmission speed is greater than the standard transmission speed, the real-time duty cycle is increased; when the actual transmission speed is less than the standard transmission speed, the real-time duty cycle is decreased.

3. The control method for the cold cathode X-ray baggage security scanner according to claim 1, characterized in that, The step of calculating the equivalent density parameter of the inspected object based on the load data and the external dimensions specifically includes: The volume of the inspected object is calculated based on the aforementioned external dimensions. The equivalent density parameter is obtained by calculating the ratio of the load data to the volume value. Multiple density control intervals are preset, and each density control interval corresponds to a set of preset negative secondary high voltage amplitude and positive high voltage rated voltage; Determine the density control range into which the equivalent density parameter falls, and call the corresponding parameters to control the cold cathode X-ray source.

4. The control method for the cold cathode X-ray baggage security scanner according to claim 1, characterized in that, The security inspection device employs dual-vision imaging, with cold cathode X-ray sources and corresponding detection units respectively arranged on the left and right sides of the transmission unit; the step of acquiring high-energy and low-energy signals transmitted through the inspected object during the period when the cold cathode X-ray source emits the beam based on the duty cycle specifically includes: Control the cold cathode X-ray sources on the left and right sides to emit X-rays toward the object being inspected; For each detection unit, the transmitted X-rays are separated and collected using the principle of layered absorption: It receives and converts the low-energy components in X-rays to obtain a low-energy signal; The residual radiation after absorption of low-energy components is subjected to energy spectrum hardening treatment; The hardened high-energy components are received and converted to obtain a high-energy signal.

5. The control method for the cold cathode X-ray baggage security scanner according to claim 4, characterized in that, The step of generating the X-ray image is followed by: The time point at which the object under test triggers the position sensor on the transmission unit is monitored, and the time difference between the object under test passing through the cold cathode X-ray sources on the left and right sides is calculated in combination with the transmission speed. Based on the time difference, the first image data and the second image data collected by the detection units on the left and right sides are aligned and registered in the spatial domain. For the overlapping area of ​​the inspected object, the first R value in the first image data and the second R value in the second image data are calculated respectively, and the corrected R value used to characterize the material properties is calculated according to the preset rules.

6. The control method for the cold cathode X-ray baggage security scanner according to claim 5, characterized in that, The steps of calculating the first R value in the first image data and the second R value in the second image data for the overlapping area of ​​the inspected object, and calculating the corrected R value for characterizing the material properties according to a preset rule, specifically include: Obtain the preset R-IL relationship curve for the material sample; Multiple high- and low-energy transmission signal points in the corresponding overlapping regions of the first image data and the second image data are selected respectively; Calculate the correlation coefficient between the data distribution of the transmitted signal points and the fitting curve of the R-IL relationship of the material sample; By comparing the fitting correlation coefficients of the first image data and the second image data respectively, the R value corresponding to the image data with the larger fitting correlation coefficient is selected as the basis for judging the material properties.

7. The control method for the cold cathode X-ray baggage security scanner according to claim 6, characterized in that, The R-IL relationship curves of the material samples are constructed by fitting the transmission data of the stepped samples under the irradiation of the cold cathode X-ray source; the R-IL relationship curves of the material samples include organic material curves, inorganic material curves and mixture curves; The step of calculating the correlation coefficient between the data distribution of the transmission signal points and the fitting curve of the R-IL relationship of the material sample includes: Calculate the correlation coefficients between the data distribution of the transmission signal points and the fitting curves of organic matter, inorganic matter, and mixture, respectively; The material category corresponding to the calculated maximum correlation coefficient is determined as the material property of the tested object.

8. A cold cathode X-ray baggage security scanner, characterized in that, include: A conveying unit is used to transport the object to be inspected. The conveying unit is equipped with a gravity sensor and a position sensor. A size detection unit is disposed above or to the side of the conveying unit and is used to detect the external dimensions of the object being inspected. A cold cathode X-ray source includes a cold cathode X-ray tube, a positive high-voltage circuit, and a negative secondary high-voltage circuit; the positive high-voltage circuit is configured to control the X-ray penetration power by adjusting the output amplitude and to control the high-voltage output time by adjusting the duty cycle; the negative secondary high-voltage circuit is configured to control the electron beam current by adjusting the voltage amplitude. The detection unit includes a high-energy detector and a low-energy detector, used to acquire X-ray transmission signals; The control unit is communicatively connected to the transmission unit, the size detection unit, the cold cathode X-ray source, and the detection unit. The control unit is configured to perform the control method for the cold cathode X-ray baggage scanner as described in any one of claims 1 to 7.

9. The cold cathode X-ray baggage security scanner according to claim 8, characterized in that, The size detection unit is one of a light curtain sensor, a 3D depth camera, or a lidar; and / or; The detection unit is an L-shaped detection unit, including a high-energy detector, a filter, and a low-energy detector; the low-energy detector, the filter, and the high-energy detector are stacked sequentially along the X-ray incident direction.

10. A computer program product, characterized in that, The system includes a computer program that, when executed by a processor, implements the control method for the cold cathode X-ray baggage scanner as described in any one of claims 1 to 7.

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