Non-solid medium quality detection method and system

Abstract

The application discloses a non-solid medium quality detection method and system, which is applied to the technical field of non-solid medium printing and comprises the following steps: acquiring an original measurement speed sequence and a flow state image; determining the current flow speed of each non-solid medium flow column from the original measurement speed sequence; performing connected domain identification and adhesion domain segmentation on the flow state image to obtain a non-solid medium flow column region; for each non-solid medium flow column region, determining a current flow interruption detection result based on the change degree of pixel values along the flow direction of the flow column, calculating a current skew angle based on the circumscribed contour boundary of the non-solid medium flow column, and calculating a current flow column width based on the edge pixel point coordinate values along the width direction of the flow column; and integrating the current flow interruption detection result, the current flow speed, the current skew angle and the current flow column width into a jet flow quality detection result. Through the above method, full-process high-precision non-solid medium quality detection is realized, and flow column optimization and product control are realized.

Description

Technical Field

[0001] This application relates to the field of non-solid media printing technology, and in particular to a method and system for non-solid media quality testing. Background Technology

[0002] With the rapid development of advanced manufacturing technologies, non-solid media printing technology, with its unique advantages such as the ability to directly form complex structures, achieve high-precision manufacturing, and expand the range of material choices, has shown great application potential in many high-end fields such as aerospace, automobile manufacturing, and biomedicine, and is gradually becoming one of the key forces driving the upgrading and transformation of the manufacturing industry.

[0003] In the printing process of non-solid media printing equipment, the quality of the non-solid media directly determines the performance and quality of the final printed product. During the flow process, the non-solid media may be affected by various factors, such as its physical properties (viscosity, surface tension, etc.), the printing environment (temperature, air pressure, etc.), and equipment operating parameters (flow rate, pressure, etc.). This can lead to instability, breakage, and displacement of the non-solid media, resulting in a series of adverse consequences, such as poor interlayer bonding, excessive surface roughness of the formed part, and internal defects, thereby affecting the reliability of printing and the performance of the finished product. Therefore, there is an urgent need for an effective solution that can detect the quality of the non-solid media in real time, comprehensively, and accurately throughout the entire printing process. Summary of the Invention

[0004] This application provides a method and system for detecting the quality of non-solid media, aiming to solve the problem of real-time, comprehensive, and high-precision detection of the quality of non-solid media during the printing process. The technical solution provided by this application is as follows:

[0005] On the one hand, this application provides a method for quality detection of non-solid media, including:

[0006] During the process of ejecting non-solid media streams in a non-solid media printing device, the original measurement velocity sequence obtained by the laser velocimeter scanning each non-solid media stream sequentially, and the flow state image obtained by the optical imaging device performing optical imaging on each non-solid media stream are acquired.

[0007] The current flow velocity of each non-solid medium column is determined from the original measured velocity sequence;

[0008] Connected domain identification and adhesion domain segmentation are performed on the flow state image to obtain each non-solid medium flow column region;

[0009] For each non-solid medium flow column region, based on the degree of pixel value change along the flow direction of the non-solid medium flow column in the region, the current flow interruption detection result is obtained by detecting whether the non-solid medium flow column in the region has been interrupted; based on the outer contour boundary of the non-solid medium flow column in the region, the current tilt angle of the non-solid medium flow column in the region is calculated; based on the coordinate values ​​of the edge pixel points along the width direction of the non-solid medium flow column in the region, the current flow column width of the non-solid medium flow column in the region is calculated.

[0010] The current flow interruption detection results, current flow velocity, current tilt angle, and current flow column width of each non-solid medium column are integrated into the non-solid medium quality detection results.

[0011] Optionally, the current flow velocity of each non-solid medium column is determined from the original measured velocity sequence, including:

[0012] Using sampling time as the independent variable and the original measurement speed as the dependent variable, an original measurement speed curve is generated based on the original measurement speed sequence;

[0013] Identify each maximum value of the original measurement speed on the original measurement speed curve, and calculate the average value of each maximum value of the original measurement speed and its set number of adjacent original measurement speeds to obtain each effective measurement speed;

[0014] Based on the flow velocity matching rule, a matching effective measurement velocity is selected from each effective measurement velocity for each non-solid medium flow column as the current flow velocity.

[0015] Optionally, the flow velocity matching rule includes at least one of the following matching rules: a first matching rule based on position synchronization characteristics, a second matching rule based on flow velocity characteristics, and a third matching rule based on time interval characteristics; when the matching results of two or more matching rules are inconsistent, the priority of the first matching rule is greater than the priority of the second matching rule, and the priority of the second matching rule is greater than the priority of the third matching rule; wherein:

[0016] The first matching rule is: based on the time synchronization characteristics between the spatial position coordinates of the laser velocimeter and the effective measured velocity, and the position synchronization characteristics between the spatial position coordinates of the laser velocimeter and the spatial position coordinates of the non-solid medium nozzle, each effective measured velocity is mapped one-to-one with each non-solid medium flow column.

[0017] The second matching rule is: based on the periodic alternation of effective and ineffective measurement velocities, each effective measurement velocity is mapped to each non-solid medium flow column according to the scanning order of the non-solid medium flow column;

[0018] The third matching rule is: based on the equal time interval characteristics between each effective measurement velocity, each effective measurement velocity is mapped one-to-one with each non-solid medium flow column according to the scanning order of the non-solid medium flow column.

[0019] Optionally, connected component identification and adhesion domain segmentation are performed on the flow state image to obtain each non-solid medium flow column region, including:

[0020] Adaptive pixel threshold segmentation is performed on the flow state image to obtain images of each initial non-solid medium flow column;

[0021] Morphological reconstruction was performed on each initial non-solid medium flow column image to obtain each reconstructed non-solid medium flow column image;

[0022] Connected components are marked on each reconstructed non-solid medium flow column image to obtain each connected region;

[0023] Based on the set of concave points in each connected region, generate the adhesion dividing line of each connected region.

[0024] Based on the set of edge lines in each connected region, generate the adhesion boundary lines of each connected region;

[0025] Based on the adhesion dividing lines and adhesion boundary lines of each connected region, each connected region is divided into adhesion segments to obtain each non-solid medium flow column region.

[0026] Optionally, based on the set of concave points in each connected region, adhesion dividing lines are generated for each connected region, including:

[0027] For each non-solid medium flow column region, a contour search algorithm is used to extract all circumscribed contours in the non-solid medium flow column region, and the circumscribed contour with the largest area is selected as the target circumscribed contour. Convex defect detection is performed on the target circumscribed contour to obtain each depression point containing the depression start point, depression end point and the deepest depression point. The depression start point, depression end point and the deepest depression point in each depression point are connected to obtain the adhesion dividing line.

[0028] Optionally, based on the set of edge lines in each connected region, the adhesion boundary lines of each connected region are generated, including:

[0029] For each non-solid medium flow column region, an edge detection algorithm is used to extract all edge lines in the non-solid medium flow column region; from all edge lines, two parallel edge lines with a parallel spacing closest to the standard flow column spacing are selected as target edge lines; the center line between the two target edge lines is used as the adhesion boundary line of the connected region.

[0030] Optionally, based on the degree of pixel value change along the flow direction of the non-solid medium in the non-solid medium flow column region, the current flow interruption detection result is obtained by detecting whether the non-solid medium flow column in the non-solid medium flow column region has been interrupted, including:

[0031] A one-dimensional scan line is generated along the flow direction of the non-solid medium column within the non-solid medium column region. Based on the pixel values ​​of each pixel on the one-dimensional scan line, a scan pixel curve is generated.

[0032] When a step jump greater than the standard pixel threshold is detected in the scanned pixel curve, the current flow interruption detection result of the non-solid medium flow column in the non-solid medium flow column region is determined to be a flow interruption.

[0033] When no step jump greater than the standard pixel threshold is detected in the scanned pixel curve, the current flow interruption detection result of the non-solid medium flow column in the non-solid medium flow column region is determined to be no flow interruption.

[0034] Optionally, based on the circumscribed contour boundary of the non-solid medium flow column in the non-solid medium flow column region, the current tilt angle of the non-solid medium flow column in the non-solid medium flow column region is calculated, including:

[0035] A contour search algorithm is used to extract all circumscribed contours in the non-solid medium flow column region, and the circumscribed contour with the largest area is selected as the target circumscribed contour.

[0036] The minimum bounding rectangle fitting algorithm is used to fit the target bounding contour to obtain the bounding contour boundary and the rotation angle of the bounding contour boundary.

[0037] Based on the rotation angle of the circumscribed contour boundary, calculate the current tilt angle of the non-solid medium column in the non-solid medium column region.

[0038] Optionally, the width of the non-solid medium flow column in the non-solid medium flow column region is calculated based on the coordinate values ​​of the edge pixel points along the width direction of the non-solid medium flow column, including:

[0039] A one-dimensional probe line is generated along the width direction of the non-solid medium flow column within the non-solid medium flow column region;

[0040] Based on the pixel values ​​of each pixel on the one-dimensional detection line, a detection pixel curve is generated;

[0041] The first-order differential operation of the probe pixel curve is performed to obtain the maximum points of each pixel as candidate edge pixels of the non-solid medium flow column in the non-solid medium flow column region;

[0042] Non-maximum suppression is applied to each candidate edge pixel to obtain the left and right edge pixels of the non-solid medium flow column in the non-solid medium flow column region;

[0043] Based on the coordinate values ​​of the left and right edge pixels, calculate the current width of the non-solid medium flow column in the non-solid medium flow column region.

[0044] On the other hand, this application provides a non-solid medium quality detection system, comprising:

[0045] The image acquisition device includes a water-cooled backlight source disposed inside the printing cavity and an optical imaging device disposed outside the printing cavity; the optical imaging device captures flow state images of each non-solid medium flow column illuminated by the backlight of the water-cooled backlight source through a first high-temperature resistant window embedded in the first side wall of the printing cavity.

[0046] The flow rate measuring device includes a laser velocity measuring device and a servo motion platform disposed outside the printing cavity. The laser velocity measuring device is mounted on the servo motion platform. While the servo motion platform drives the laser velocity measuring device to move along the arrangement direction of the non-solid medium flow columns, the laser velocity measuring device scans each non-solid medium flow column sequentially along the arrangement direction of the non-solid medium flow columns through a second high-temperature resistant viewing window embedded in the second side wall of the printing cavity to obtain the original measurement velocity sequence.

[0047] The main control unit, connected to the image acquisition device and the flow rate measurement device, is used to execute the above-mentioned non-solid medium quality detection method.

[0048] The beneficial effects of this application are as follows:

[0049] This application achieves high-precision quality detection of non-solid media printing equipment throughout the entire process by acquiring flow state images with an image acquisition device, acquiring original measurement velocity sequences with a flow velocity measurement device, and performing non-solid media quality detection by a main control device based on the flow state images and original measurement velocity sequences. This enables jet optimization and product control of non-solid media printing equipment, providing an important basis for subsequent parameter adjustment and equipment optimization of non-solid media printing equipment.

[0050] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings. Attached Figure Description

[0051] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0052] Figure 1 This is a schematic diagram of the composition and structure of the non-solid medium quality detection system in the embodiments of this application;

[0053] Figure 2 This is a schematic flowchart illustrating the non-solid medium quality detection method in the embodiments of this application;

[0054] Figure 3 This is a schematic diagram of the flow state image in an embodiment of this application;

[0055] Figure 4 This is a schematic diagram of the original measured velocity curve of the non-solid medium flow column in the embodiments of this application;

[0056] Figure 5 This is a schematic diagram of a one-dimensional scan line of a non-solid medium flow column in an embodiment of this application;

[0057] Figure 6 This is a schematic diagram of a one-dimensional probe line of a non-solid medium flow column in an embodiment of this application;

[0058] Figure 7 This is a schematic diagram of the hardware structure of the main control device in the embodiments of this application. Detailed Implementation

[0059] To make the objectives, technical solutions, and beneficial effects of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the 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.

[0060] To facilitate a better understanding of this application by those skilled in the art, the technical terms used in this application will be briefly introduced below.

[0061] Non-solid media printing equipment uses non-solid media such as liquids, pastes, slurries, aerosols, and gels as the forming medium, and deposits and forms materials through methods such as jetting, extrusion, and coating. It is widely used in high-end fields such as precision metal manufacturing, biomedicine, electronic packaging, and ceramic molding. Non-solid media printing equipment includes, but is not limited to: liquid metal 3D printing equipment, inkjet electronic printing equipment, and photocurable resin printing equipment. Liquid metal 3D printing equipment uses molten metal (such as molten aluminum, molten copper, or molten titanium alloy) as the non-solid medium, which is ejected through a nozzle to form a liquid column, which is then directly formed after cooling. It is used in fields such as aerospace precision parts and heat dissipation structures for electronic devices. Inkjet electronic printing equipment uses conductive ink (silver nanoparticle suspension), insulating ink, etc., as the non-solid medium, which is ejected through piezoelectric / thermal bubble nozzles. It is used in fields such as printed circuit boards, flexible electronic devices, and sensor electrodes. Photocurable resin printing equipment uses photosensitive resin as the non-solid medium, which is selectively cured and formed by ultraviolet light. It is used in fields such as precision molds, dental restorations, and cultural and creative products.

[0062] An optical imaging device is a backlit imaging device that forms a flow state image by backlighting a non-solid medium column in a flow process.

[0063] A laser velocimeter is a non-contact velocimeter that uses a laser beam to irradiate a moving non-solid medium column, and then uses the Doppler effect to detect changes in the echo frequency and convert them into flow velocity.

[0064] A servo motion platform is a speed control device that drives a laser velocimeter to move at a constant speed along the direction of the non-solid medium flow column.

[0065] It should be noted that the terms "first," "second," etc., used in this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein.

[0066] After introducing the technical terms used in this application, the application scenarios and design concepts of this application will be briefly introduced next.

[0067] In the current research and application of 3D printing technology for non-solid media (such as liquid metal), researchers and engineers are focusing their efforts on optimizing the nozzles for non-solid media. Through continuous experimentation with new materials, improvements to nozzle structure design, and optimization of nozzle manufacturing processes, they are committed to enhancing the performance of non-solid media nozzles and achieving more stable and precise non-solid media jetting. For example, advanced nanomaterials are used to manufacture nozzles to improve their wear resistance and high-temperature resistance; nozzles with special flow channel structures are designed to improve the flow characteristics of non-solid media; and precision machining techniques are employed to ensure the dimensional accuracy and surface quality of the nozzles.

[0068] However, focusing solely on optimizing the non-solid media nozzle is far from sufficient. The quality of the non-solid media is a crucial monitoring indicator in the non-solid media 3D printing process, directly determining the performance and quality of the final printed product. During the jetting of the non-solid media, the media stream can be affected by various factors, such as the physical properties of the liquid metal (viscosity, surface tension, etc.), the printing environment (temperature, air pressure, etc.), and equipment operating parameters (jet speed, pressure, etc.), leading to instability, breakage, and displacement of the media stream. If these problems are not detected and corrected in time, they will trigger a series of serious consequences, such as poor interlayer bonding, excessive surface roughness of the formed part, and internal defects, ultimately affecting the reliability of the entire printing process and the performance of the finished product.

[0069] Unfortunately, there is currently no effective testing system on the market capable of real-time, comprehensive, and accurate monitoring of the quality of non-solid media. Existing testing methods are mostly limited to post-printing inspection of the finished product. This post-printing approach not only fails to promptly identify and address problems that arise during the printing process, but also often results in significant waste of materials and time, increasing manufacturing costs if the finished product fails inspection.

[0070] To this end, this application develops a non-solid media quality detection system and method suitable for non-solid media printing equipment. The non-solid media quality detection system includes an image acquisition device, a flow rate measurement device, and a main control device connected to both the image acquisition device and the flow rate measurement device. The image acquisition device includes a water-cooled backlight source located inside the printing cavity and an optical imaging device located outside the printing cavity. The optical imaging device captures images of each non-solid media column illuminated by the water-cooled backlight source through a first high-temperature resistant window embedded in the first sidewall of the printing cavity, obtaining an image of the flow state. The flow rate measurement device includes a laser velocity measuring device and a servo motion platform located outside the printing cavity. The laser velocity measuring device is mounted on the servo motion platform. While the servo motion platform drives the laser velocity measuring device to move along the non-solid media column arrangement direction, the laser velocity measuring device sequentially scans each non-solid media column along the non-solid media column arrangement direction through a second high-temperature resistant window embedded in the second sidewall of the printing cavity, obtaining an original measurement velocity sequence. During the ejection of non-solid medium columns in the non-solid medium printing equipment, the main control device acquires the original measured velocity sequence obtained by the laser velocimeter scanning each non-solid medium column and the flow state image of each non-solid medium column captured by the optical imaging device. It determines the current flow velocity of each non-solid medium column from the original measured velocity sequence; it performs connected component identification and adhesion domain segmentation on the flow state images to obtain each non-solid medium column region; and for each non-solid medium column region, it detects the non-solid medium based on the degree of pixel value change along the flow direction of the non-solid medium column. The system obtains the current flow interruption detection result by determining whether the non-solid medium flow column in the medium flow column region has experienced a flow interruption; it calculates the current tilt angle of the non-solid medium flow column in the non-solid medium flow column region based on the outer contour boundary of the non-solid medium flow column in the non-solid medium flow column region; it calculates the current flow column width of the non-solid medium flow column in the non-solid medium flow column region based on the coordinate values ​​of the edge pixel points along the width direction of the non-solid medium flow column in the non-solid medium flow column region; and it integrates the current flow interruption detection result, current flow velocity, current tilt angle, and current flow column width of each non-solid medium flow column into a non-solid medium quality detection result.

[0071] In this way, by acquiring flow state images through an image acquisition device, acquiring original measurement velocity sequences through a flow velocity measurement device, and performing non-solid medium quality detection based on the flow state images and original measurement velocity sequences by the main control device, high-precision quality detection of the entire process of non-solid medium printing equipment can be achieved. This enables jet optimization and product control of non-solid medium printing equipment, providing an important basis for subsequent parameter adjustment and equipment optimization of non-solid medium printing equipment.

[0072] After introducing the application scenarios and design concepts of this application, the technical solutions provided by this application will be described in detail below.

[0073] This application provides a non-solid medium quality detection system, see below. Figure 1 As shown, the non-solid medium quality detection system provided in this application embodiment includes:

[0074] The image acquisition device includes a water-cooled backlight source disposed inside the printing cavity and an optical imaging device disposed outside the printing cavity; the optical imaging device captures flow state images of each non-solid medium flow column illuminated by the backlight of the water-cooled backlight source through a first high-temperature resistant window embedded in the first side wall of the printing cavity.

[0075] The flow rate measuring device includes a laser velocity measuring device and a servo motion platform disposed outside the printing cavity. The laser velocity measuring device is mounted on the servo motion platform. While the servo motion platform drives the laser velocity measuring device to move along the arrangement direction of the non-solid medium flow columns, the laser velocity measuring device scans each non-solid medium flow column sequentially along the arrangement direction of the non-solid medium flow columns (that is, the direction perpendicular to the flow direction of the non-solid medium flow columns) through a second high-temperature resistant viewing window embedded in the second side wall of the printing cavity to obtain the original measurement velocity sequence.

[0076] The main control unit, connected to the image acquisition device and the flow velocity measurement device, is used to acquire the original measurement velocity sequence obtained by the laser velocimeter scanning each non-solid medium flow column sequentially and the flow state image obtained by the optical imaging device optically imaging each non-solid medium flow column during the ejection of non-solid medium flow columns in the non-solid medium printing equipment. It determines the current flow velocity of each non-solid medium flow column from the original measurement velocity sequence; performs connected component identification and adhesion domain segmentation on the flow state image to obtain each non-solid medium flow column region; and for each non-solid medium flow column region, it calculates the flow velocity along the non-solid medium flow column based on the flow direction within the non-solid medium flow column region. The system detects whether the non-solid medium flow column in the non-solid medium flow column region has experienced a flow interruption based on the degree of pixel value change. It then calculates the current skew angle of the non-solid medium flow column in the region based on the outer contour boundary of the non-solid medium flow column. Finally, it calculates the current flow column width based on the coordinates of the edge pixels along the width direction of the non-solid medium flow column. The system integrates the current flow interruption detection result, current flow velocity, current skew angle, and current flow column width of each non-solid medium flow column into a non-solid medium quality detection result.

[0077] In this embodiment, the laser velocimetry device can be a laser Doppler velocimeter, which samples the flow velocity of a non-solid medium column based on the Doppler effect. Specifically, if the non-solid medium is not a scattering medium, tracer particles, such as titanium oxide, carbon soot, or specially made microparticles, can be added to it. The particle concentration and particle diameter (e.g., 0.1-10 μm) of the tracer particles are experimentally selected to balance signal intensity and background noise, and to have strong tracking and astigmatism properties, ensuring that the tracer particles can effectively follow the flow of the non-solid medium to accurately reflect the flow velocity of the non-solid medium column. If the non-solid medium is a scattering medium, such as liquid metal, the surface roughness and oxide film of the liquid metal itself can be used as tracer particles, eliminating the need for additional tracer particles and enabling non-contact velocimetry in a high-temperature, enclosed environment. The velocimetry principle of the laser velocimetry device is as follows:

[0078] The laser velocimetry device emits two coherent laser beams that intersect to form an interference fringe region. The width of this interference fringe region is less than or equal to the width of a single non-solid dielectric column, preventing aliasing of velocity signals from adjacent non-solid dielectric columns. When a non-solid dielectric column flows through this interference fringe region, it scatters the laser light. The frequency of the scattered light undergoes a Doppler shift due to the motion of the tracer particles, satisfying the following formula:

[0079]

[0080] in, For Doppler frequency shift, For the refractive index of a non-solid medium, The wavelength of the laser. For flow velocity, The angle between the beams is denoted as .

[0081] The laser velocimetry device collects scattered laser light, which is converted into an electrical signal by a photodetector (such as a photomultiplier tube). This electrical signal is then filtered by a bandpass filter to remove low-frequency noise, and the Doppler frequency shift is analyzed by a spectrum analyzer (such as a Fast Fourier Transform / FFT) or a frequency tracker. Then, combined with optical path geometry parameters (such as...) , ) and non-solid media properties (such as Doppler frequency shift Substituting the above formula into the real-time inverse simulation of particle velocity The velocity of the tracer particle This represents the local flow velocity of a non-solid medium column.

[0082] In practical applications, in one embodiment, the servo motion platform sequentially stops at the location of each non-solid medium flow column. The interference fringe region formed by the intersection of two coherent laser beams emitted by the laser velocimeter is directly opposite the location of the non-solid medium flow column. As the non-solid medium flow column continuously flows through the interference fringe region, the laser velocimeter outputs a raw measurement velocity sequence. This raw measurement velocity sequence contains each raw measurement velocity (i.e., tracer particle velocity) arranged sequentially according to the sampling time. The main control device averages each raw measurement velocity in the raw measurement velocity sequence to obtain the current flow velocity of the non-solid medium flow column. In this velocimeter method, although each tracer particle is measured only once, the average velocity of a large number of tracer particles can represent the macroscopic flow velocity of the non-solid medium flow column.

[0083] In another embodiment, a servo motion platform drives a laser velocimetry device to move along the direction of the non-solid medium flow columns. Simultaneously, the interference fringe region formed by the intersection of two coherent laser beams emitted by the laser velocimetry device passes sequentially through each non-solid medium flow column. When the interference fringe region passes through a non-solid medium flow column, an effective measurement segment is formed. When the interference fringe region passes through the gap between two non-solid medium flow columns, an invalid measurement segment is formed. The duration of the effective measurement segment is determined by the moving speed of the servo motion platform and the diameter of the non-solid medium flow column. The value of this duration ensures that the number of effective measurement velocities collected within this duration is greater than a set threshold (e.g., 10), thereby ensuring the accuracy of the current flow velocity of the non-solid medium flow column. After the servo motion platform drives the laser velocimetry device to scan all non-solid medium flow columns, that is, after one scanning cycle is completed, the laser velocimetry device outputs a raw measurement velocity sequence. This raw measurement velocity sequence contains various raw measurement velocities arranged sequentially according to the sampling time. These raw measurement velocities exhibit a periodic alternation characteristic of "peak-valley-peak". The peak value corresponds to the effective measurement segment (i.e., the non-solid medium flow column region), and the valley value corresponds to the gap between two non-solid medium flow columns (invalid measurement velocities are approximately equal to 0). The main control device extracts the maximum value of each raw measurement velocity from the raw measurement velocity sequence, calculates the average value of each raw measurement velocity maximum value and its set number of adjacent raw measurement velocities to obtain each effective measurement velocity, and selects the matching effective measurement velocity from each non-solid medium flow column as the current flow velocity based on the flow velocity matching rule (the specific matching rule is detailed below). In this velocity measurement method, a velocity time series for each non-solid medium flow column can be constructed through multiple scanning cycles. This velocity time series contains the flow velocity of the non-solid medium flow column measured in multiple scanning cycles, which can reflect the overall flow velocity state of the non-solid medium flow column rather than the instantaneous flow velocity at a single point, and is more conducive to the detection of abnormal flow velocity.

[0084] In this embodiment, the laser velocimetry device utilizes the Euler measurement principle of laser Doppler velocimetry to measure the current flow velocity of a non-solid medium column. Specifically, it measures the flow velocity of the non-solid medium column flowing through the interference fringe region without tracking tracer particles flowing through it. By transforming the tracer particle tracking problem into a sampling point statistics problem, a servo motion platform carrying the laser velocimetry device sequentially scans each non-solid medium column, achieving spatial coverage of multiple non-solid medium columns. The flow velocity time sequence (i.e., velocity time series) is reconstructed through multiple scanning cycles, enabling monitoring of the velocity time series of each non-solid medium column. This is a key technical means to overcome the contradiction between the continuous flow of the non-solid medium column and the real-time detection requirement, thus enabling reliable flow velocity monitoring even under the physical reality of continuous non-solid medium column flow.

[0085] In one possible implementation, the water-cooled backlight source is positioned facing the lens of the optical imaging device, and each non-solid dielectric flow column is located between the water-cooled backlight source and the optical imaging device.

[0086] In one possible implementation, the image acquisition device further includes:

[0087] A narrow-band filter is installed at the front of the lens of an optical imaging device, and its center wavelength is matched with the emission wavelength of the water-cooled backlight source.

[0088] In one possible implementation, the main control device further includes a human-machine interface for inputting the number of jets, jet spacing, and probe line width of the non-solid medium flow column.

[0089] In one possible implementation, both the first and second high-temperature resistant windows are optical windows made of quartz glass or sapphire crystal.

[0090] In one possible implementation, the first high-temperature resistant window and the second high-temperature resistant window are tilted at a set angle (e.g., 15-30°) and embedded in the side wall of the printing cavity. That is, there is a tilt angle (e.g., 15-30°) between the first high-temperature resistant window and the second high-temperature resistant window and the side wall plane of the printing cavity, so as to prevent liquid metal vapor from condensing and depositing on the surface of the first high-temperature resistant window and the second high-temperature resistant window.

[0091] In one possible implementation, the servo motion platform includes:

[0092] Linear guide rails are used to support the laser velocimetry device to move along the direction of the non-solid medium flow column (that is, the direction perpendicular to the flow direction of the non-solid medium flow column). The travel range covers the total width of each non-solid medium flow column and leaves a set margin (such as a margin of 20% of the total width of each non-solid medium flow column).

[0093] Servo motors are used to drive the laser velocimetry device to move at a constant speed along a linear guide rail. The speed of movement is adjustable within a set range (e.g., 10-100 mm / s).

[0094] An absolute encoder is used to provide real-time feedback of the spatial position coordinates of the laser velocimetry device to the main control device.

[0095] Limit switches limit the safe range of motion of the laser velocimetry device.

[0096] In one possible implementation, the non-solid medium quality detection system provided in this application embodiment further includes:

[0097] The thermal protection device includes a cooling system controller, a first water-cooling jacket that encloses the water-cooled backlight source, and a second water-cooling jacket that encloses the edges of the first and second high-temperature resistant windows.

[0098] In one possible implementation, the second water-cooling jacket forms an annular cooling channel around the first and second high-temperature resistant windows.

[0099] In one possible implementation, the thermal protection device further includes:

[0100] A temperature sensor is embedded in the first and second water cooling jackets to monitor the coolant temperature in the first and second water cooling jackets in real time and form a closed-loop feedback with the cooling system controller.

[0101] In one possible implementation, the non-solid medium quality detection system provided in this application embodiment further includes:

[0102] The synchronization control device is connected to the main control device, the image acquisition device, and the flow velocity measurement device. It is used to provide synchronization trigger signals to the optical imaging device and the laser velocimetry device under the control of the main control device.

[0103] In one possible implementation, the synchronization control device includes:

[0104] The timing controller is connected to the main control device, the image acquisition device, and the flow velocity measurement device, and is used to provide synchronous trigger signals to the image acquisition device and the flow velocity measurement device under the control of the main control device.

[0105] A high-precision clock source, connected to the timing controller, is used to provide a reference clock for the timing controller.

[0106] In one possible implementation, the main control device includes:

[0107] The data caching unit is used to cache the flow state image and the original measurement velocity sequence respectively, and then pack and transmit the flow state image and the original measurement velocity sequence to the data processing unit after aligning them with timestamps.

[0108] The data processing unit is used to determine the current flow velocity of each non-solid medium column from the original measured velocity sequence; to perform connected component identification and adhesion domain segmentation on the flow state image to obtain each non-solid medium column region; for each non-solid medium column region, based on the degree of pixel value change along the flow direction of the non-solid medium column in the region, to detect whether the non-solid medium column in the region has experienced a flow interruption and obtain the current flow interruption detection result; based on the outer contour boundary of the non-solid medium column in the region, to calculate the current tilt angle of the non-solid medium column in the region; based on the coordinate values ​​of the edge pixel points along the width direction of the non-solid medium column in the region, to calculate the current column width of the non-solid medium column in the region; and to integrate the current flow interruption detection result, current flow velocity, current tilt angle, and current column width of each non-solid medium column into a non-solid medium quality detection result.

[0109] In one possible implementation, the main control device further includes:

[0110] The status monitoring unit is used to monitor the working status of the water-cooled backlight source, optical imaging device, laser velocimetry device and servo motion platform in real time, and triggers protection shutdown when an abnormal working status is detected.

[0111] The defect warning unit is used to send a STOP signal or parameter adjustment command to the main control system of the non-solid media printing equipment when a flow interruption, out-of-tolerance flow column width, or abnormal flow velocity is detected.

[0112] The self-learning optimization unit is used to train a process parameter prediction model (such as a machine learning model) based on historical non-solid media quality inspection data, and dynamically optimize the printing parameters of the non-solid media printing equipment (such as the jet pressure and jet temperature of the non-solid media nozzle array) based on the process parameter prediction model.

[0113] Based on the above embodiments, this application provides a method for detecting the quality of non-solid media, applied to the main control device of the aforementioned non-solid media quality detection system, see reference. Figure 2 As shown, the general flow of the non-solid medium quality detection method provided in this application embodiment is as follows:

[0114] Step 201: During the process of ejecting non-solid media streams in the non-solid media printing device, acquire the original measurement velocity sequence obtained by the laser velocimeter scanning each non-solid media stream sequentially, and acquire the flow state image obtained by the optical imaging device performing optical imaging on each non-solid media stream.

[0115] In this embodiment, a servo motion platform equipped with a laser velocimetry device sequentially and uniformly scans multiple parallel non-solid medium flow columns within the printing cavity along the arrangement direction of the non-solid medium flow columns, simultaneously acquiring the original flow velocity data of each non-solid medium flow column to form an original measurement velocity sequence; simultaneously, an optical imaging device performs optical imaging on the multiple parallel non-solid medium flow columns within the printing cavity, illuminated by a water-cooled backlight source, to obtain a flow state image; wherein, the flow state image is as follows... Figure 3 The grayscale image shown.

[0116] Step 202: Determine the current flow velocity of each non-solid medium column from the original measured velocity sequence.

[0117] In this embodiment of the application, when determining the current flow velocity of each non-solid medium column from the original measured velocity sequence, the following methods may be used, but are not limited to:

[0118] First, using sampling time as the independent variable and the original measurement speed as the dependent variable, an original measurement speed curve is generated based on the original measurement speed sequence; where the original measurement speed curve is as follows: Figure 4 As shown, the x-axis represents the sampling time, which can be determined based on the sampling timestamp carried by the original measurement speed, and the y-axis represents the original measurement speed.

[0119] Then, identify the maximum values ​​of each original measurement speed on the original measurement speed curve, and calculate the average of each maximum value and its set number of adjacent original measurement speeds to obtain each effective measurement speed. Specifically, the original measurement speed curve can be smoothed using a Gaussian kernel function to obtain a smoothed measurement speed curve. After identifying the maximum values ​​of each measurement speed on the smoothed measurement speed curve, calculate the average of each maximum value and its set number (e.g., two before and two after) of adjacent measurement speeds to obtain each effective measurement speed.

[0120] Finally, based on the flow velocity matching rule, a matching effective measurement velocity is selected from each of the effective measurement velocities for each non-solid medium flow column as the current flow velocity. The flow velocity matching rule includes at least one of the following: a first matching rule based on position synchronization characteristics, a second matching rule based on flow velocity characteristics, and a third matching rule based on time interval characteristics.

[0121] In practical implementation, under the synchronous triggering of the synchronous control device, the laser velocimetry device outputs the original measured velocity in real time, while the servo motion platform synchronously feeds back the spatial coordinate position of the laser velocimetry device. This allows the main control device to obtain the original measured velocity and spatial coordinate position with synchronized sampling time. In other words, the sampling time of each original measured velocity in the original measured velocity sequence obtained by the main control device is synchronized with the sampling time of each spatial coordinate position in the spatial coordinate position sequence. Based on this, the first matching rule based on the position synchronization characteristic is: based on the time synchronization characteristic between the spatial position coordinates of the laser velocimetry device and the effective measured velocity, and the position synchronization characteristic between the spatial position coordinates of the laser velocimetry device and the spatial position coordinates of the non-solid medium nozzle, each effective measured velocity is mapped one-to-one with each non-solid medium flow column. Specifically, the spatial position coordinates of each non-solid medium nozzle in the non-solid medium nozzle array are fixed and can be pre-configured in the main control device. When matching the effective measurement velocity and the non-solid medium flow column, the main control device can transform the spatial coordinates of each laser velocimeter and each non-solid medium nozzle in the spatial coordinate position sequence to the same coordinate system, such as the world coordinate system. The origin O of the world coordinate system is the geometric center of the printing cavity or a corner point, the X-axis is parallel to the direction of the non-solid medium flow column, the Y-axis is perpendicular to the direction of the non-solid medium flow column, and the Z-axis is the flow direction of the non-solid medium flow column. Based on the sampling time of each original maximum measurement velocity, the sampling time of each effective measurement velocity is determined. Based on the sampling time of each effective measurement velocity and the sampling time of each spatial coordinate of the laser velocimeter, the spatial coordinates of the laser velocimeter corresponding to the sampling time of each effective measurement velocity are determined. For each effective measurement velocity, the absolute deviation between the spatial coordinates of the laser velocimeter corresponding to the effective measurement velocity and the spatial coordinates of each non-solid medium nozzle is calculated, and the effective measurement velocity is determined as the current flow velocity of the non-solid medium flow column ejected by the non-solid medium nozzle whose absolute deviation is less than the first allowable error range.

[0122] When the laser velocimeter scans onto a non-solid medium flow column, its initial measurement velocity is the flow velocity of that column. When the laser velocimeter scans other locations (i.e., the gap between two non-solid medium flow columns), its initial measurement velocity is almost zero. Based on this, the second matching rule based on flow velocity characteristics is: based on the periodic alternation of effective and ineffective measurement velocities, each effective measurement velocity is mapped one-to-one with each non-solid medium flow column according to the scanning sequence. Specifically, the spatial coordinates of each non-solid medium nozzle in the non-solid medium nozzle array are fixed. The scanning path can be determined based on the spatial coordinates of each nozzle and pre-configured in the main control device. The main control device also records the pre-configured standard flow velocities of the non-solid medium flow columns. When matching effective measurement velocities with non-solid medium flow columns, the main control device can replace each maximum value of the original measurement velocity on the original measurement velocity curve (or smoothed measurement velocity curve) with the corresponding effective measurement velocity. Based on the flow velocity characteristics that the velocity amplitude of the effective measurement segment approaches the standard flow velocity of the non-solid medium flow column and the velocity amplitude of the invalid measurement segment approaches zero, it identifies the effective and invalid measurement segments on the original measurement velocity curve (or smoothed measurement velocity curve). The effective measurement velocity in the first effective measurement segment is determined as the current flow velocity of the non-solid medium flow column ejected by the first non-solid medium nozzle on the scanning path. The effective measurement velocity in the second effective measurement segment is determined as the current flow velocity of the non-solid medium flow column ejected by the second non-solid medium nozzle on the scanning path, and so on, until the matching determination of all effective measurement velocities with non-solid medium flow columns is completed.

[0123] The laser velocimetry device scans the non-solid medium flow column at equal time intervals, and a fixed scanning speed is internally set. The position and velocity of the non-solid medium flow column are determined by the time interval between each effective measurement speed. Based on this, the third matching rule based on the time interval characteristic is: based on the equal time interval characteristic between each effective measurement speed, each effective measurement speed is mapped one-to-one with each non-solid medium flow column according to the scanning order of the non-solid medium flow column. Specifically, the spatial position coordinates of each non-solid medium nozzle in the non-solid medium nozzle array are fixed. The standard spatial position spacing between each non-solid medium nozzle can be determined based on the spatial position coordinates of each non-solid medium nozzle and pre-configured in the main control device. The main control device also records the pre-configured fixed scanning speed and fixed time interval of the non-solid medium flow column. When matching effective measurement velocities with non-solid medium flow columns, the main control device can determine the sampling time of each effective measurement velocity based on the sampling time of each original maximum measurement velocity; calculate the actual time interval between each effective measurement velocity based on the sampling time of each effective measurement velocity; and map the actual time interval between each effective measurement velocity to the actual spatial position spacing between each effective measurement velocity based on a fixed scanning speed. If the absolute error between the actual spatial position spacing of two adjacent effective measurement velocities and the standard spatial position spacing of two adjacent non-solid medium nozzles is less than the second allowable error range, and the absolute error between the actual time interval of the two adjacent effective measurement velocities and the fixed time interval is... If the difference is less than the third allowable error range, then the two adjacent effective measured velocities are determined to belong to the non-solid medium flow column ejected by the two adjacent non-solid medium nozzles. According to the sampling time order of the two adjacent effective measured velocities and the scanning order of the two adjacent non-solid medium nozzles, the two adjacent effective measured velocities are sequentially determined as the current flow velocity of the non-solid medium flow column ejected by the two adjacent non-solid medium nozzles. That is, the effective measured velocity sampled earlier is determined as the current flow velocity of the non-solid medium flow column ejected by the non-solid medium nozzle scanned earlier, and the effective measured velocity sampled later is determined as the current flow velocity of the non-solid medium flow column ejected by the non-solid medium nozzle scanned later.

[0124] By using any one of the three matching rules described above, a matching effective measured velocity can be selected from each effective measured velocity for each non-solid medium flow column as the current flow velocity. To further improve the accuracy of flow velocity matching, two or more of the three matching rules can be combined to select a matching effective measured velocity from each effective measured velocity for each non-solid medium flow column as the current flow velocity. For example, when the matching results of two or more matching rules are consistent, the current flow velocity of each non-solid medium flow column is determined to be valid; when the matching results of two or more matching rules are inconsistent, the current flow velocity of each non-solid medium flow column matched by the highest priority matching rule is determined to be valid. The first matching rule has a higher priority than the second matching rule, and the second matching rule has a higher priority than the third matching rule.

[0125] Step 203: Perform connected component identification and adhesion domain segmentation on the flow state image to obtain each non-solid medium flow column region; for each non-solid medium flow column region, based on the degree of pixel value change along the flow direction of the non-solid medium flow column in the non-solid medium flow column region, detect whether the non-solid medium flow column in the non-solid medium flow column region has been interrupted to obtain the current interruption detection result; based on the outer contour boundary of the non-solid medium flow column in the non-solid medium flow column region, calculate the current tilt angle of the non-solid medium flow column in the non-solid medium flow column region; based on the edge pixel coordinate values ​​along the width direction of the non-solid medium flow column in the non-solid medium flow column region, calculate the current flow column width of the non-solid medium flow column in the non-solid medium flow column region.

[0126] In this embodiment of the application, when performing connected component identification and adhesion domain segmentation on the flow state image to obtain each non-solid medium flow column region, the following methods may be used, but are not limited to:

[0127] First, adaptive pixel thresholding is performed on the flow state image to obtain images of each initial non-solid medium flow column. Specifically, the flow state image can be resized and smoothed (e.g., Gaussian blur or median filtering) to obtain a smooth flow state image, so as to reduce noise caused by smoke, steam, etc. generated by high temperature while maintaining the aspect ratio. Then, based on the neighborhood pixel value change characteristics of the smooth flow state image, the segmentation threshold is dynamically calculated, and the flow state image is segmented based on the segmentation threshold to obtain images of each initial non-solid medium flow column.

[0128] Then, morphological reconstruction is performed on each initial non-solid medium flow column image to obtain reconstructed non-solid medium flow column images. Specifically, for each initial non-solid medium flow column image, a morphological opening operation (erosion followed by dilation) and a morphological closing operation (dilation followed by erosion) are sequentially performed to obtain the reconstructed non-solid medium flow column image. In this way, the morphological opening operation (erosion followed by dilation) removes small noise points and initially separates adjacent non-solid medium flow column regions; the morphological closing operation (dilation followed by erosion) fills in small pores within the non-solid medium flow column regions, making the non-solid medium flow column regions more coherent.

[0129] Secondly, connected component marking is performed on each reconstructed non-solid medium flow column image to obtain each connected region. Furthermore, non-solid medium flow columns are typically elongated; therefore, in each connected region, the height of the non-solid medium flow column is approximately the same as the height of the connected region, while the width of the non-solid medium flow column is less than the width of the connected region. Simultaneously, connected regions with excessively small areas may be noise or broken regions, while connected regions with excessively large areas may be regions where multiple non-solid medium flow columns are adhered together. Based on this, connected regions can be filtered according to the geometric characteristics of the non-solid medium flow columns, such as area, length, and width. Specifically, connected regions with areas smaller than the standard non-solid medium flow column area can be removed. Connected regions whose area difference from the standard non-solid medium flow column area is less than an area threshold are identified as non-solid medium flow column regions. Connected regions with areas larger than the standard non-solid medium flow column area are identified as regions where non-solid medium flow columns are adhered together, and subsequent adhesion segmentation processing is performed.

[0130] Next, depression point analysis is performed on each connected region to obtain a set of depression points in each connected region. Based on the set of depression points in each connected region, adhesion dividing lines are generated for each connected region. Specifically, for each non-solid medium flow column region, a contour search algorithm can be used to extract all circumscribed contours in the non-solid medium flow column region, and the circumscribed contour with the largest area is selected as the target circumscribed contour. Convex defect detection is performed on the target circumscribed contour to obtain each depression point containing the depression start point, depression end point, and deepest depression point. The depression start point, depression end point, and deepest depression point in each depression point are connected to obtain the adhesion dividing lines. Of course, each connected region can also be converted into a gradient graph (such as the Sobel operator), and the watershed algorithm can be used to detect the watershed line in the gradient graph of each connected region, and the watershed line can be used to replace the adhesion dividing line. In the gradient graph, the larger the gradient value, the steeper the terrain (ridge), and the smaller the value, the bottom of the basin. The boundary of the adhesion non-solid medium flow column corresponds to a high gradient value (ridge), and the interior has a low gradient value (basin). The adhesion non-solid medium flow column presents multiple adjacent basins in the gradient graph, and the watershed line is the dividing boundary between the non-solid medium flow columns.

[0131] Subsequently, edge line detection is performed on each connected region to obtain a set of edge lines in each connected region. Based on the set of edge lines in each connected region, the adhesion boundary line of each connected region is generated. Specifically, for each non-solid medium flow column region, an edge detection algorithm (such as the Canny algorithm) can be used to extract each edge image in the non-solid medium flow column region; Hough transform is used to detect straight lines in each edge image as edge lines; from all edge lines, two mutually parallel edge lines with a parallel spacing closest to the standard flow column spacing are selected as target edge lines; the center line between the two target edge lines is used as the adhesion boundary line of the connected region.

[0132] Finally, based on the adhesion dividing lines and adhesion boundary lines of each connected region, the connected regions are segmented to obtain each non-solid medium flow column region. Specifically, for each non-solid medium flow column region, the adhesion dividing lines and adhesion boundary lines of the connected region are compared. If the two are basically in the same position, the adhesion dividing lines or adhesion boundary lines are used to segment the connected region. Alternatively, the adhesion boundary lines with higher accuracy can be used, or the center lines of the adhesion dividing lines and adhesion boundary lines can be used. If the depression point analysis does not find an adhesion dividing line (e.g., parallel adhesion), but the edge line detection finds a clear adhesion boundary line, the adhesion boundary line is directly used to segment the connected region. If the edge line detection does not find a clear adhesion boundary line due to noise or other reasons, but the depression point analysis finds an adhesion dividing line, the adhesion dividing line is directly used to segment the connected region.

[0133] Furthermore, the previously screened non-solid medium flow column regions and the non-solid medium flow column regions after adhesion and segmentation can be counted to obtain the number of non-solid medium flow columns. In addition, on the one hand, the non-solid medium flow column regions can be further screened based on known input data (such as the number of columns and the distance between the jet outlets) to eliminate false detections and recount; on the other hand, inter-frame information between consecutive frames of flow column state images can be used to confirm the counting results by tracking the movement of the non-solid medium flow columns, further screening the non-solid medium flow column regions and improving robustness. Afterwards, the detected non-solid medium flow column regions can be marked on the flow column state image using bounding boxes, and the number of columns can be output.

[0134] In this embodiment, if the flow of the non-solid medium column is interrupted, the pixel value (i.e., grayscale value) will typically change gradually along the flow direction of the non-solid medium column. Simultaneously, detection can be performed at the location of the non-solid medium column, transforming global detection into localized targeted detection, greatly improving robustness and efficiency while reducing interference and false detection rates. Based on this, when detecting whether the non-solid medium column in the region has experienced a flow interruption based on the degree of pixel value change along the flow direction of the non-solid medium column, the following methods can be used, but are not limited to:

[0135] First, within the region of the non-solid medium flow column, a flow direction along the non-solid medium flow column is generated, such as... Figure 5 The one-dimensional scan line shown in red generates a scan pixel curve (i.e., grayscale change curve) based on the pixel values ​​(i.e., grayscale values) of each pixel on the one-dimensional scan line; the one-dimensional scan line can be located at the center line position of the non-solid medium flow column region.

[0136] Then, when a step jump greater than the standard pixel threshold is detected in the scanned pixel curve, the current flow interruption detection result of the non-solid medium flow column in the non-solid medium flow column region is determined to be a flow interruption; when no step jump greater than the standard pixel threshold is detected in the scanned pixel curve, the current flow interruption detection result of the non-solid medium flow column in the non-solid medium flow column region is determined to be no flow interruption. Specifically, for a continuous and uniform non-solid medium flow column, its scanned pixel curve (i.e., grayscale change curve) usually fluctuates smoothly around a low grayscale value (representing dark color), and there should be no drastic, cliff-like jumps; that is, the acceptable index (OK) is: the curve is generally flat, showing a dark plateau shape, and slight gradual changes in grayscale are allowed, as long as the changes are smooth and continuous (e.g., one end is slightly brighter and the other slightly darker due to lighting); the unacceptable index (NG / defect) is: the curve shows obvious step jumps. For example: the grayscale value suddenly jumps from 50 (dark color) to 200 (light color), and then jumps back to 50. This abrupt change clearly indicates a flow interruption in the non-solid medium column, disrupting its continuity. Therefore, the scan pixel curve can be smoothed first to obtain a smoothed scan pixel curve; then, it can be detected whether there is a step-like change greater than a standard pixel threshold in the smoothed scan pixel curve to determine whether the current flow interruption detection result of the non-solid medium column in the non-solid medium column region indicates a flow interruption (synchronously outputting the flow interruption position) or no flow interruption.

[0137] Furthermore, in this embodiment, after determining that the current flow interruption detection result of the non-solid medium flow column in the non-solid medium flow column region has occurred, the servo motion platform equipped with an optical coherence tomography (OCT) device (which is 90° orthogonal to the optical path of the optical imaging device to avoid cross-interference) can be controlled to move to the flow interruption position of the non-solid medium flow column in the non-solid medium flow column region and then pause. The OCT device starts single-point scanning and performs axial tomographic scanning on the non-solid medium flow column below the flow interruption position to obtain the structural interference signal inside the non-solid medium flow column and send it to the main control device. The main control device performs reflected light intensity distribution analysis on the structural interference signal to further identify whether the non-solid medium flow column has experienced internal flow interruption. If the non-solid medium flow column is in a continuous flow state, the reflected signal decays uniformly (exponential decay curve); if the non-solid medium flow column experiences internal flow interruption, the reflected signal shows a sudden drop (air gap) or a strong scattering peak (impurity blockage). In this way, by further detecting whether the non-solid medium flow column has internal flow interruption through optical coherence tomography, grayscale misjudgment caused by surface bubbles and reflection can be effectively eliminated, and the flow interruption misjudgment rate can be reduced.

[0138] In this embodiment of the application, when calculating the current tilt angle of the non-solid medium flow column in the non-solid medium flow column region based on the outer contour boundary of the non-solid medium flow column in the non-solid medium flow column region, the following methods may be used, but are not limited to:

[0139] First, a contour finding algorithm (such as the findContours algorithm in OpenCV) is used to extract all circumscribed contour regions in the non-solid medium flow column region, and the circumscribed contour region with the largest area is selected as the target circumscribed contour region.

[0140] Then, a minimum bounding rectangle fitting algorithm (such as the minAreaRect algorithm) is used to fit the minimum bounding rectangle of the target bounding contour region, obtaining the bounding contour boundary and its rotation angle. For example, using the minAreaRect algorithm, the coordinates of the center point (x, y), width and height (width, height), and rotation angle of the minimum bounding rectangle are output.

[0141] Finally, based on the rotation angle of the circumscribed boundary, the current tilt angle of the non-solid medium column in the non-solid medium column region is calculated. Specifically, the rotation angle of the circumscribed boundary can be determined as the current tilt angle of the non-solid medium column in the non-solid medium column region.

[0142] In this embodiment of the application, when calculating the current width of the non-solid medium flow column in the non-solid medium flow column region based on the coordinate values ​​of the edge pixel points along the width direction of the non-solid medium flow column, the following methods may be used, but are not limited to:

[0143] First, within the region of the non-solid medium flow column, a flow is generated along the width direction of the non-solid medium flow column, as shown below. Figure 6 The red line represents a one-dimensional detection line, and a detection pixel curve is generated based on the pixel values ​​of each pixel on the one-dimensional detection line. The width of the one-dimensional detection line is greater than the width of the non-solid medium flow column. For example, the width of the one-dimensional detection line... satisfy , The maximum estimated width of the non-solid medium flow column; the generation position of the one-dimensional probe line can be a fixed position, such as the middle position of the non-solid medium flow column region, or a dynamic position, such as using at least one of the following dynamic position generation strategies based on adaptive changes in the spatial distribution of the non-solid medium flow column to generate the one-dimensional probe line:

[0144] Centroid tracking method: Calculate the centroid coordinates of the non-solid medium flow column region, and generate a one-dimensional probe line along the flow direction perpendicular to the non-solid medium flow column using the centroid coordinates.

[0145] Maximum width priority method: Scan the location of the maximum width in the non-solid medium flow column region, and place the one-dimensional probe line at the location of the maximum width (to ensure coverage of the widest area).

[0146] Motion prediction method: Based on the motion speed of the servo motion platform and the center point coordinates of the non-solid medium flow column in the non-solid medium flow column region predicted in the previous N frames, the center point coordinates of the non-solid medium flow column in the current frame are predicted by Kalman filtering; along the direction perpendicular to the flow direction of the non-solid medium flow column, a one-dimensional detection line is generated by the center point coordinates.

[0147] One-dimensional probe lines can be dynamically generated using any one of the three dynamic position generation strategies described above. To further improve the accuracy of the one-dimensional probe lines, two or more of the three strategies can be combined. For example, if the positions of the one-dimensional probe lines generated by two or more strategies are consistent, the probe line is considered valid. If the positions are inconsistent, the probe line generated by the strategy with the highest priority is considered valid. The priority of the dynamic position generation strategies is as follows: centroid tracking method has a higher priority than maximum width first method, which in turn has a higher priority than motion prediction method.

[0148] In addition, considering that the non-solid medium column is constantly flowing, the width of the non-solid medium column also varies within a narrow range. Therefore, the flow column state image can be re-acquired at intervals, and the detection line can be regenerated in the aforementioned manner, and the detection pixel curve can be generated based on the pixel value of each pixel point on the one-dimensional detection line.

[0149] Then, the first-order differential operation is performed on the probe pixel curve to obtain the maxima of each pixel, which are then used as candidate edge pixels of the non-solid dielectric flow column in the non-solid dielectric flow column region. Specifically, the probe pixel curve can first be smoothed using a Gaussian smoothing filter to obtain a smoothed probe pixel curve, and then the first-order differential operation is performed on the smoothed probe pixel curve to obtain the maxima of each pixel, which are then used as candidate edge pixels of the non-solid dielectric flow column in the non-solid dielectric flow column region. The Gaussian smoothing filter kernel is generated by a Gaussian function, and its two-dimensional mathematical expression is as follows:

[0150]

[0151] Where x and y represent the pixel coordinates of the distance from the center of the filter; The standard deviation of the Gaussian distribution determines the width of the filter; It is a normalization constant that ensures the sum of the filter coefficients is 1.

[0152] Secondly, non-maximum suppression processing is performed on each candidate edge pixel to obtain the left and right edge pixels of the non-solid medium flow column in the non-solid medium flow column region.

[0153] Finally, based on the coordinate values ​​of the left and right edge pixels, the width of the non-solid medium flow column in the non-solid medium flow column region is calculated.

[0154] Step 204: Integrate the current flow interruption detection results, current flow velocity, current tilt angle, and current flow column width of each non-solid medium column into a non-solid medium quality detection result.

[0155] In this embodiment of the application, when integrating the current flow interruption detection result, current flow velocity, current tilt angle and current flow column width of each non-solid medium flow column into the non-solid medium quality detection result, the timestamp can be used as a reference. In another embodiment, the working state of the non-solid medium nozzle corresponding to each non-solid medium column can be determined based on the current flow velocity and current column width of each non-solid medium column and integrated into the non-solid medium quality detection results. This allows for dynamic optimization of the printing parameters of the non-solid medium printing equipment (such as the injection pressure and injection temperature of the non-solid medium nozzle array) based on the non-solid medium quality detection results. Specifically, if the current flow velocity is normal but the current column width changes abruptly, it can be determined that the non-solid medium nozzle has local deformation (flow velocity remains unchanged, cross-sectional area changes). If the current flow velocity changes abruptly but the current column width is normal, it can be determined that the non-solid medium nozzle has fluctuations in the feeding pressure (overall flow velocity changes, nozzle remains unchanged). If both the current flow velocity and the current column width change abruptly, it can be determined that the non-solid medium nozzle has signs of impending flow interruption or severe blockage.

[0156] After introducing the non-solid medium quality detection system and method provided in the embodiments of this application, the main control device provided in the embodiments of this application will be briefly introduced next.

[0157] See Figure 7 As shown, the main control device 700 provided in this application embodiment includes at least a processor 701, a memory 702, and a computer program stored in the memory 702 and executable on the processor 701. When the processor 701 executes the computer program, it implements the above-mentioned non-solid medium quality detection method provided in this application embodiment.

[0158] In one possible implementation, processor 701 can be a single processing element or a collective term for multiple processing elements. For example, processor 701 can be a central processing unit (CPU), or one or more integrated circuits configured to implement the non-solid media quality detection method provided in the embodiments of this application. Specifically, processor 701 can be a general-purpose processor, including but not limited to CPUs, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0159] In one possible implementation, memory 702 may include a readable medium in the form of volatile memory, such as random access memory (RAM) 7021 and / or cache memory 7022, and may further include read-only memory (ROM) 7023; memory 702 may also include a program tool 7025 having a set (at least one) of program modules 7024, including but not limited to: operating subsystem, one or more application programs, other program modules, and program data, each or some combination of these examples may include an implementation of a network environment.

[0160] In one possible implementation, the main control device 700 provided in this application embodiment may further include a bus 703 connecting different components (including processor 701 and memory 702). The bus 703 represents one or more types of bus structures, including memory bus, peripheral bus, local area bus, etc.

[0161] In one possible implementation, the main control device 700 can also communicate with one or more devices that allow user interaction (e.g., mobile phones, computers, etc.), and / or with one or more devices that enable it to communicate with other non-solid media printing devices (e.g., routers, modems, etc.), and other external devices 704. This communication can be performed via an input / output (I / O) interface 705. Furthermore, the main control device 700 can also communicate with one or more networks (e.g., local area networks (LANs), wide area networks (WANs), and / or public networks, such as the Internet) via a network adapter 706. Figure 7 As shown, network adapter 706 communicates with other modules of the main control unit 700 via bus 703. It should be understood that, although... Figure 7 As not shown, other hardware and / or software modules can be used in conjunction with the main control unit 700, including but not limited to microcode, device drivers, redundant processors, external disk drive arrays, Redundant Arrays of Independent Disks (RAID) subsystems, tape drives, and data backup storage subsystems.

[0162] It should be noted that, Figure 7 The main control device 700 shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0163] Furthermore, this application also provides a computer-readable storage medium storing computer instructions. When executed by a processor, these computer instructions implement the non-solid media quality detection method described above in this application. Specifically, the computer instructions may be built into or installed in a processor, enabling the processor to implement the non-solid media quality detection method described above in this application by executing the built-in or installed computer instructions.

[0164] Of course, the non-solid medium quality detection method provided in the embodiments of this application can also be implemented as a program product, which includes program code. When the program code is executed by a processor, it implements the non-solid medium quality detection method provided in the embodiments of this application.

[0165] The program product provided in this application embodiment can be any combination of one or more readable media, wherein the readable media can be a readable signal medium or a readable storage medium, and the readable storage medium can be, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or apparatus, or any combination thereof. Specifically, more specific examples of readable storage media (a non-exhaustive list) include: electrical connections with one or more wires, portable disks, hard disks, RAM, ROM, erasable programmable read-only memory (EPROM), optical fibers, portable compact disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0166] It should be noted that although several units or sub-units of the device have been mentioned in the detailed description above, this division is merely exemplary and not mandatory. In fact, according to embodiments of this application, the features and functions of two or more units described above can be embodied in one unit. Conversely, the features and functions of one unit described above can be further divided and embodied by multiple units.

[0167] Furthermore, although the operations of the method of this application are described in a specific order in the accompanying drawings, this does not require or imply that these operations must be performed in that specific order, or that all the operations shown must be performed to achieve the desired result. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps.

[0168] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0169] Obviously, those skilled in the art can make various modifications and variations to the embodiments of this application without departing from the spirit and scope of the embodiments of this application. Therefore, if these modifications and variations to the embodiments of this application fall within the scope of the claims of this application and their equivalents, this application also intends to include these modifications and variations.

Claims

1. A method for detecting the quality of a non-solid medium, characterized in that, include: During the process of ejecting non-solid media streams in a non-solid media printing device, the original measurement velocity sequence obtained by the laser velocimeter scanning each non-solid media stream sequentially, and the flow state image obtained by the optical imaging device performing optical imaging on each non-solid media stream are acquired. The current flow velocity of each non-solid medium column is determined from the original measured velocity sequence; The flow state image is subjected to connected component identification and adhesion domain segmentation to obtain each non-solid medium flow column region; For each non-solid medium flow column region, based on the degree of change of pixel values ​​along the flow direction of the non-solid medium flow column in the non-solid medium flow column region, the current flow interruption detection result is obtained by detecting whether the non-solid medium flow column in the non-solid medium flow column region has been interrupted. Based on the outer contour boundary of the non-solid medium flow column in the non-solid medium flow column region, calculate the current tilt angle of the non-solid medium flow column in the non-solid medium flow column region; Based on the coordinate values ​​of the edge pixels in the non-solid medium flow column region along the width direction of the non-solid medium flow column, the current flow column width of the non-solid medium flow column in the non-solid medium flow column region is calculated. The current flow interruption detection results, current flow velocity, current tilt angle, and current flow column width of each non-solid medium column are integrated into the non-solid medium quality detection results.

2. The method for detecting the quality of non-solid media as described in claim 1, characterized in that, Determining the current flow velocity of each non-solid medium column from the original measured velocity sequence includes: Using sampling time as the independent variable and the original measurement speed as the dependent variable, an original measurement speed curve is generated based on the original measurement speed sequence; Identify each maximum value of the original measurement speed on the original measurement speed curve, and calculate the average value of each maximum value of the original measurement speed and its set number of adjacent original measurement speeds to obtain each effective measurement speed; Based on the flow velocity matching rule, a matching effective measurement velocity is selected from each effective measurement velocity for each non-solid medium flow column as the current flow velocity.

3. The method for detecting the quality of non-solid media as described in claim 2, characterized in that, The flow velocity matching rule includes at least one of the following matching rules: a first matching rule based on position synchronization characteristics, a second matching rule based on flow velocity characteristics, and a third matching rule based on time interval characteristics; when the matching results of two or more matching rules are inconsistent, the priority of the first matching rule is greater than the priority of the second matching rule, and the priority of the second matching rule is greater than the priority of the third matching rule; wherein: The first matching rule is: based on the time synchronization characteristics between the spatial position coordinates of the laser velocimeter and the effective measured velocity, and the position synchronization characteristics between the spatial position coordinates of the laser velocimeter and the spatial position coordinates of the non-solid medium nozzle, each effective measured velocity is mapped one-to-one with each non-solid medium flow column. The second matching rule is as follows: based on the periodic alternation of effective and ineffective measurement velocities, each effective measurement velocity is mapped to each non-solid medium flow column according to the scanning order of the non-solid medium flow column; The third matching rule is as follows: based on the equal time interval characteristics between each effective measurement velocity, each effective measurement velocity is mapped one-to-one with each non-solid medium flow column according to the scanning order of the non-solid medium flow column.

4. The method for detecting the quality of non-solid media as described in claim 1, characterized in that, The flow state image is subjected to connected component identification and adhesion domain segmentation to obtain various non-solid medium flow column regions, including: Adaptive pixel threshold segmentation is performed on the flow state image to obtain images of each initial non-solid medium flow column; Morphological reconstruction was performed on each initial non-solid medium flow column image to obtain each reconstructed non-solid medium flow column image; Connected components are marked on each reconstructed non-solid medium flow column image to obtain each connected region; Based on the set of concave points in each connected region, generate the adhesion dividing line of each connected region. Based on the set of edge lines in each connected region, generate the adhesion boundary lines of each connected region; Based on the adhesion dividing lines and adhesion boundary lines of each connected region, each connected region is divided into adhesion segments to obtain each non-solid medium flow column region.

5. The method for detecting the quality of non-solid media as described in claim 4, characterized in that, Based on the set of concave points in each connected region, adhesion dividing lines are generated for each connected region, including: For each non-solid medium flow column region, a contour search algorithm is used to extract all circumscribed contours in the non-solid medium flow column region, and the circumscribed contour with the largest area is selected as the target circumscribed contour; convex defect detection is performed on the target circumscribed contour to obtain each concave point containing the concave initiation point, concave end point, and deepest concave point; the concave initiation point, concave end point, and deepest concave point in each concave point are connected to obtain the adhesion dividing line.

6. The method for detecting the quality of non-solid media as described in claim 4, characterized in that, Based on the set of edge lines in each connected region, the adhesion boundary lines of each connected region are generated, including: For each non-solid medium flow column region, an edge detection algorithm is used to extract all edge lines in the non-solid medium flow column region; from all edge lines, two parallel edge lines with a parallel spacing closest to the standard flow column spacing are selected as target edge lines; the center line between the two target edge lines is taken as the adhesion boundary line of the connected region.

7. The method for detecting the quality of non-solid media as described in claim 1, characterized in that, Based on the degree of pixel value change along the flow direction of the non-solid medium in the non-solid medium flow column region, the current flow interruption detection result is obtained by detecting whether the non-solid medium flow column in the non-solid medium flow column region has been interrupted, including: A one-dimensional scan line is generated along the flow direction of the non-solid medium column within the non-solid medium column region. Based on the pixel values ​​of each pixel on the one-dimensional scan line, a scan pixel curve is generated. When a step jump greater than the standard pixel threshold is detected in the scanned pixel curve, the current flow interruption detection result of the non-solid medium flow column in the non-solid medium flow column region is determined to be a flow interruption. When no step jump greater than the standard pixel threshold is detected in the scanned pixel curve, the current flow interruption detection result of the non-solid medium flow column in the non-solid medium flow column region is determined to be no flow interruption.

8. The method for detecting the quality of non-solid media as described in claim 1, characterized in that, Based on the circumscribed boundary of the non-solid medium flow column in the non-solid medium flow column region, the current tilt angle of the non-solid medium flow column in the non-solid medium flow column region is calculated, including: A contour search algorithm is used to extract all circumscribed contours in the non-solid medium flow column region, and the circumscribed contour with the largest area is selected as the target circumscribed contour. The minimum bounding rectangle fitting algorithm is used to fit the target bounding contour to obtain the bounding contour boundary and the rotation angle of the bounding contour boundary. Based on the rotation angle of the outer contour boundary, calculate the current tilt angle of the non-solid medium flow column in the non-solid medium flow column region.

9. The method for detecting the quality of non-solid media as described in claim 1, characterized in that, Based on the coordinate values ​​of the edge pixels along the width direction of the non-solid medium flow column in the non-solid medium flow column region, the width of the non-solid medium flow column in the non-solid medium flow column region is calculated, including: A one-dimensional detection line is generated along the width direction of the non-solid medium flow column within the region of the non-solid medium flow column. Based on the pixel values ​​of each pixel on the one-dimensional detection line, a detection pixel curve is generated; Perform a first-order differential operation on the detected pixel curve to obtain the maximum value points of each pixel as candidate edge pixels of the non-solid medium flow column in the non-solid medium flow column region; Non-maximum suppression processing is performed on each candidate edge pixel to obtain the left and right edge pixels of the non-solid medium flow column in the non-solid medium flow column region; Based on the coordinate values ​​of the left edge pixel and the right edge pixel, the width of the non-solid medium flow column in the non-solid medium flow column region is calculated.

10. A non-solid medium quality detection system, characterized in that, include: The image acquisition device includes a water-cooled backlight source disposed inside the printing cavity and an optical imaging device disposed outside the printing cavity. The optical imaging device captures flow state images of each non-solid medium column illuminated by the water-cooled backlight source through a first high-temperature resistant window embedded in the first side wall of the printing cavity. A flow rate measuring device includes a laser velocity measuring device and a servo motion platform disposed outside the printing cavity. The laser velocity measuring device is mounted on the servo motion platform. While the servo motion platform drives the laser velocity measuring device to move along the arrangement direction of the non-solid medium flow columns, the laser velocity measuring device scans each non-solid medium flow column sequentially along the arrangement direction of the non-solid medium flow columns through a second high-temperature resistant viewing window embedded in the second side wall of the printing cavity to obtain the original measurement velocity sequence. A main control device, connected to the image acquisition device and the flow rate measurement device, is used to execute the non-solid medium quality detection method as described in any one of claims 1-9.

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