Multi-jet single droplet real-time observation device, observation method, and 3D printing system

Abstract

In order to solve the technical problems that the existing droplet observation device cannot monitor the multi-nozzle printing process and the overall observation precision is low, the present application provides a multi-nozzle single droplet real-time observation device, an observation method and a 3D printing system.The observation device of the present application can make the observation camera capture the current working printing nozzle and automatically focus on it in real time through the cooperation of the first steering engine and the displacement platform, and complete the real-time monitoring of the printing state of the printing nozzle; through the high-frequency multiple flashing of the LED flash, the observation camera can capture the images of the same droplet at multiple times in one shot, at the same time, the high-frequency deflection of the piezoelectric deflection mirror and the telecentric lens are matched with each other, the overlapping images of the single droplet at adjacent moments are separated, so that a single photo can have enough droplet images to show the forming process, the overall observation precision is improved, the quality monitoring and fault diagnosis problems during additive manufacturing are improved, and the waste rate of electronic 3D printing is reduced.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing, specifically relating to a real-time observation device and control method for a single droplet from multiple nozzles. Background Technology

[0002] Electron 3D printing is an emerging technology that can print circuit boards and electronic devices, with broad application prospects in curved circuits, flexible electronics, and other fields. During 3D printing, real-time monitoring of the printhead's operating status using a droplet observation device helps in online control of circuit printing quality.

[0003] Existing droplet observation devices typically set the monitoring camera and the print head to be relatively stationary, ensuring the camera remains focused on the print head to obtain real-time operational data. Because the spatial positions of the camera and print head are relatively fixed, the quality of the acquired images is relatively stable. After system processing, a conclusion can be drawn regarding whether the printing process is normal. Its disadvantages are:

[0004] 1. Because the focus position of the monitoring camera is relatively fixed, it can only monitor the 3D printing process of a single nozzle and cannot monitor the printing process of multiple nozzles.

[0005] 2. Because the monitoring process determines whether the printhead is working properly by capturing the shape of different droplets in the same spatial position, the overall observation accuracy is relatively low. Summary of the Invention

[0006] To address the technical problems of existing droplet observation devices being unable to monitor multi-nozzle printing processes and having low overall observation accuracy, this invention provides a real-time observation device, observation method, and 3D printing system for single droplets in multi-nozzle applications.

[0007] The technical solution of this invention is:

[0008] The multi-nozzle single droplet real-time observation device is unique in that it includes a first servo motor, a second servo motor, a displacement platform, an observation camera, a lens, a piezoelectric deflector, an LED flash, and a control system.

[0009] The observation camera is mounted on the displacement platform and observes through the lens; the displacement platform is used to provide linear motion for the observation camera and the lens to achieve focusing.

[0010] The displacement platform is mounted on the first servo motor, which is used to provide rotational motion to the observation camera and lens, causing them to rotate to a specified observation angle.

[0011] The piezoelectric deflector is mounted on the second servo motor, which provides rotational motion to the piezoelectric deflector so that it rotates to a specified optical path refraction position, thereby achieving optical path adjustment.

[0012] The LED flash is mounted on the side wall of the lens barrel, and the outgoing light path of the LED flash is parallel to the optical axis of the lens;

[0013] The positional relationship between the first servo motor and the second servo motor satisfies the following condition: the two work together to form the optical path of LED flash - piezoelectric deflection mirror - currently working print head - piezoelectric deflection mirror - lens - observation camera;

[0014] The control system is used to control the operation of the first servo motor, the second servo motor, the displacement platform, the observation camera, the piezoelectric deflector and the LED flash;

[0015] The LED flash is controlled to turn on and off by the control system and is triggered simultaneously with the printhead of the printer that is currently in operation, and flashes at fixed frequency intervals; the relationship between the droplet images captured by the observation camera and the time sequence can be established by the switching sequence of the LED flash;

[0016] During each shooting session of the observation camera, the piezoelectric deflector and the LED flash move in sync and repeatedly. Each change in the position of the piezoelectric deflector causes a shift in the droplet image, separating the overlapping parts of the droplet images at adjacent moments. This allows the observation camera to obtain images of the same droplet at multiple moments in a single shot.

[0017] Furthermore, the lens is a telecentric lens.

[0018] Furthermore, both the first and second servos are servos capable of 360° rotation.

[0019] Furthermore, the LED flash is a light-emitting LED with a fast response.

[0020] Furthermore, both the first and second servo motors are mounted on the 3D printer's work plate, which serves as a reference.

[0021] Furthermore, the control system is developed based on a PLC.

[0022] The present invention also provides a method for real-time observation of a single droplet from multiple nozzles using the above-mentioned multi-nozzle single-droplet real-time observation device, characterized in that it includes the following steps:

[0023] Step 1: Focus;

[0024] The control system controls the rotation of the first and second servo motors to form the optical path from LED flash to piezoelectric deflector to the print head to be used, then to the lens and finally to the observation camera.

[0025] The control system controls the movement of the displacement platform until the image from the observation camera is clear and the focus is achieved;

[0026] Step 2: Take the photo;

[0027] The control system triggers the observation camera. During each shooting session, the piezoelectric deflector and LED flash are controlled to move in sync and continuously multiple times. In this way, images of the same droplet at multiple moments can be obtained in each shooting session.

[0028] This invention also provides a multi-nozzle 3D printing system with real-time droplet observation function, including multiple printing nozzles and a motion slide for driving the printing nozzles; its special feature is that it also includes the aforementioned multi-nozzle single droplet real-time observation device; the control system in the multi-nozzle single droplet real-time observation device is also used to switch the printing nozzles to work alternately; the multi-nozzle single droplet real-time observation device is used to acquire droplet images generated by the currently working printing nozzle among the multiple printing nozzles.

[0029] The beneficial effects of this invention are:

[0030] 1. The observation device of the present invention, through the cooperation of the first servo motor and the displacement platform, adjusts the position of the observation camera to focus with the currently working printing nozzle, enabling the observation camera to capture the currently working printing nozzle in real time and automatically focus with it, thus completing real-time monitoring of the printing status of the printing nozzle; through the high-frequency LED flash lamp flashing multiple times, the observation camera can capture images of the same droplet at multiple moments in a single photograph. At the same time, the high-frequency deflection of the piezoelectric deflection mirror and the telecentric lens work together to separate the overlapping images of a single droplet at adjacent moments, effectively avoiding the phenomenon of droplet image overlap and distortion caused by the high number of exposures and high speed in traditional observation devices, ensuring the authenticity of the outline projection of the measured droplet, so that a single photograph can have enough droplet images to show the droplet forming process, improving the overall observation accuracy, improving the quality monitoring and fault diagnosis of the additive manufacturing production process, and reducing the scrap rate of electronic 3D printing.

[0031] 2. The moving parts in the observation device of this invention adopt high-precision, fast-response components. For example, the displacement platform is driven by a stepper motor and a ball screw, and the droplet separation is achieved by a piezoelectric deflection mirror, which improves the accuracy and real-time performance of droplet observation during the printing process.

[0032] 3. The control system (computer + drive controller) of the 3D printing system with droplet observation function of the present invention is developed based on PLC. It is simple and reliable, and integrates functions such as coarse / fine adjustment of transmission system, nozzle action control, nozzle switching, component reset, automatic focusing / fine adjustment of telecentric lens, automatic shooting, image processing, emergency stop, and warning.

[0033] 4. The present invention has a simple structure and good reliability. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the observation device of the present invention.

[0035] Figure 2 This is a schematic diagram showing the installation position of the observation camera in the observation device of the present invention.

[0036] Figure 3 This is a schematic diagram of the piezoelectric deflector mechanism in the observation device of the present invention.

[0037] Figure 4 This is a schematic diagram of the movement of the observation system after the nozzle of the observation device of the present invention is switched.

[0038] Figure 5 This is the LED light pulse sequence 1 (alignment calibration timing) of the observation device of the present invention.

[0039] Figure 6 This is the LED light pulse sequence 2 of the observation device of the present invention.

[0040] Figure 7 This is the logic control diagram for the focusing process.

[0041] Figure 8 This is the logic control diagram of the observation device.

[0042] Explanation of reference numerals in the attached figures:

[0043] 1. Working board; 2. Circuit printing nozzle; 3. Structure printing nozzle; 4. Pneumatic slide; 5. First servo motor; 6. Servo board of the first servo motor; 7. Observation camera; 8. Displacement platform; 9. Telecentric lens; 10. Second servo motor; 11. Servo board of the second servo motor; 12. Piezoelectric deflector; 13. Mounting hole for LED flash. Detailed Implementation

[0044] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0045] like Figure 1 As shown, the multi-nozzle single droplet real-time observation device of the present invention includes a first servo motor 5, a second servo motor 10, a displacement platform 8, an observation camera 7, a telecentric lens 9, a piezoelectric deflector 12, an LED flash lamp, and a control system.

[0046] Both the first servo motor 5 and the second servo motor 10 are mounted on the 3D printer's work plate 1, with the work plate 1 as the reference. The positional relationship between the first servo motor 5 and the second servo motor 10 satisfies the following condition: the telecentric lens 9 and the piezoelectric deflector 12 on them can form an optical path from the printing nozzle to the piezoelectric deflector 12, the telecentric lens 9, and the observation camera 7. Both the first servo motor 5 and the second servo motor 10 are servo motors capable of 360° rotation, and can output rotational motion after inputting a pulse electrical signal.

[0047] like Figure 2 As shown, the displacement platform 8 is a two-dimensional moving platform. The displacement platform 8 is mounted on the servo plate 6 of the first servo 5. The observation camera 7 is mounted on the displacement platform 8 and uses a telecentric lens 9 for observation. In this embodiment, the driving component of the displacement platform 8 consists of a stepper motor and a ball screw. The ball screw is used to convert the rotational motion of the stepper motor into linear motion.

[0048] The first servo motor 5 provides rotational motion for the observation camera 7, allowing it to rotate to a specified observation angle. The servo plate 6 of the first servo motor contacts the displacement platform 8, providing support. The displacement platform 8 provides linear motion for the observation camera 7 and the telecentric lens 9, enabling the observation camera 7 to adjust its focus and achieve focus on the observation point. The telecentric lens 9, as part of the optical path, provides the observation camera 7 with an image of the observation point. Therefore, through the rotation of the first servo motor 5 and the linear movement of the observation camera 7 on the displacement platform 8, the position of the telecentric lens 9 can be changed, thus achieving focus. Compared to non-telecentric lenses, the preferred telecentric lens 9 in this embodiment has a fixed optical magnification, preventing different magnifications due to varying object distances. This avoids the phenomenon of larger images captured at close range and smaller images captured at distant ranges during shooting, reducing the distortion coefficient to below 0.1%, eliminating parallax during shooting, and resulting in clear imaging.

[0049] like Figure 3As shown, the servo plate 11 of the second servo motor 10 is an L-shaped servo plate, and the piezoelectric deflector 12 is mounted on the vertical plate of the L-shaped multi-machine plate. The second servo motor 10 is used to provide rotational motion for the piezoelectric deflector 12, so that the piezoelectric deflector 12 rotates to the correct optical path refraction position (at this time, the image of the print head can be displayed in the image captured by the observation camera 7), thereby realizing optical path adjustment. The piezoelectric deflector 12 includes a plane mirror and four piezoelectric ceramics. Through the inverse piezoelectric effect, the thickness of the four piezoelectric ceramics changes after the input pulse electrical signal, thereby quickly and accurately driving the plane mirror to perform a slight deflection, so that the images of the droplets that are superimposed in space are separated, and an image of the formation process of a single droplet is obtained. Therefore, through the rotation of the second servo motor 10 and the high-speed deflection of the piezoelectric deflector 12 itself, a clear observation of a single droplet can be achieved.

[0050] The LED flash (not shown in the figure) uses a fast-response LED and is located at the LED flash mounting hole 13 on the side wall of the telecentric lens 9, with the emitted beam parallel to the optical axis of the telecentric lens 9. The LED flash is controlled by a drive controller and is triggered simultaneously with the printhead to be printed, flashing rapidly at fixed frequency intervals. Figure 6 The timing diagram sets the switching sequence of the LED flash (high level to turn on, low level to turn off), thereby establishing a connection between the droplet image and the timing sequence. The control system includes a computer and a drive controller; the computer is used to issue working instructions to the drive controller; the drive controller is used to control the actions of the first servo motor 5, the second servo motor 10, the observation camera 7, the telecentric lens 9, the displacement platform 8, the piezoelectric deflector 12, and the jetting system of the 3D printer according to the received working instructions.

[0051] The basic principle of this invention is:

[0052] The telecentric lens 9 has a fixed optical magnification. The entire optical path originates from the nozzle of the currently operating printhead, enters through the piezoelectric deflector 12, is refracted by the piezoelectric deflector 12, and then reaches the telecentric lens 9. The observation angle of the telecentric lens 9 can be adjusted by rotating the first servo motor 5, making its observation direction parallel to the optical path refracted by the piezoelectric deflector 12. The linear movement of the displacement platform 8 can cause the observation camera 7 and the telecentric lens 9 to translate together, thereby adjusting the position of the telecentric lens 9 so that the focal point of the telecentric lens 9 coincides with the observation point (the observation point is the area below the nozzle of the currently operating printhead, where the morphology of the formed droplets can be observed), thus completing the focusing work of the currently operating printhead.

[0053] Once focusing is complete, a shooting command is triggered, causing the piezoelectric deflector 12 to deflect. The change in the position of the piezoelectric deflector 12 achieves lateral image shift, which is simultaneously captured by the observation camera 7. By repeatedly shifting the image, the entire process from droplet generation to ejection can be captured within a single camera opening time. At this point, the droplet's flight trajectory is predicted using the principle of free fall motion by analyzing the relationship between the droplet image and the time sequence, and the initial velocity and acceleration information of the droplet are calculated using the equation of motion.

[0054] Droplet separation principle:

[0055] The droplet formation process is extremely brief, lasting only tens of microseconds, and capturing the morphology of droplets during this process requires exposure times on the order of microseconds. Therefore, this invention, by altering the pulse sequence of the LED flash, allows for the capture of multiple droplet images at a single moment in a single photograph, thus recording the entire droplet formation process. Since images of individual droplet formation processes at adjacent moments spatially overlap, the tilt angle of the plane mirror in the piezoelectric deflector 12 is changed so that the image position of the droplet during each exposure is offset linearly along the droplet's direction of motion compared to the previous moment. This offset is greater than or equal to the height of the overlapping portion of the droplet images, thereby separating the overlapping images and obtaining images of the formation process of the dispersed individual droplets.

[0056] While multiple exposures within the same time frame can cause droplet overlap in the original image, after droplet image separation, a larger number of images (e.g., 5 droplet images) can better display the entire droplet formation process. Conversely, reducing the number of exposures to avoid droplet image overlap results in too few droplets in the original image (e.g., only 2 droplet images), making it impossible to accurately display the entire droplet formation process.

[0057] The following describes the usage of the multi-nozzle single droplet real-time observation device of the present invention, taking its application in a dual-nozzle 3D printer as an example.

[0058] The dual-nozzle 3D printer includes a work plate 1, a structural printing nozzle 3, and a circuit printing nozzle 2. The structural printing nozzle 3 and the circuit printing nozzle 2 are each mounted on the work plate 1 via a pneumatic slide 4. The printer can precisely move the position of the corresponding printing nozzle as needed to perform printing work.

[0059] Upon power-on reset, the dual-nozzle 3D printer's work plate 1 starts up and moves to the appropriate position. The structural printing nozzle 3 begins to work, printing the substrate material. Simultaneously, the second servo motor 10 rotates to adjust the angle of the piezoelectric deflector 12, and the first servo motor 5 rotates to adjust the angle of the observation camera 7, forming the optical path as follows: LED flash – piezoelectric deflector 12 – structural printing nozzle 3 – piezoelectric deflector 12 – telecentric lens 9 – observation camera 7. Figure 4As shown, the observation camera 7 then adjusts the focus position through the linear movement of the displacement platform 8 to make the image clear and complete the focusing work.

[0060] Once focusing is complete, a shooting command is triggered. The piezoelectric deflector 12 deflects slightly to separate the overlapping droplet images. The images are then transmitted to a subsequent image processing and analysis system (which can use commercially available image analysis and processing software such as OpenCV or LabVIEW) to predict the droplet landing point.

[0061] After the structural printing nozzle 3 finishes its work and resets, the circuit printing nozzle 2 moves to the working position via the 3D printer's own displacement mechanism and pneumatic slide 4 to begin printing. At the same time, the first servo motor 5 and the second servo motor 10 rotate to adjust the position of the observation camera 7, the telecentric lens 9, and the piezoelectric deflector 12, forming the optical path from the LED flash to the piezoelectric deflector 12, then to the circuit printing nozzle 2, the piezoelectric deflector 12, the telecentric lens 9, and the observation camera 7. The observation camera 7 and the telecentric lens 9 move via the displacement platform 8 to refocus. After focusing, the image is captured. The piezoelectric deflector 12 slightly deflects to separate the overlapping droplet images. The images are then transmitted to the subsequent image processing and analysis system to predict the droplet landing point.

[0062] Applying the multi-nozzle single droplet real-time observation device of the present invention to an existing multi-nozzle 3D printer can create a 3D printing system with real-time droplet observation functionality. The control principle is explained below using a dual-nozzle 3D printer as an example:

[0063] Once the observation device is started, the computer sends a start command to the device drive controller, causing the rotation system (first servo motor 5 and second servo motor 10), focusing system (observation camera 7, telecentric lens 9, and displacement platform 8), galvanometer system (piezoelectric deflector 12), and the 3D printer's jetting system (circuit printing nozzle 2, structure printing nozzle 3, and pneumatic slide 4) to reset. After each system resets, the drive controller uses the pneumatic slide 4 to move the nozzle to be printed (the observed nozzle) to the set working position and begins adjusting the position of the observation camera 7 so that it can clearly capture images of the print nozzle to be observed.

[0064] First, the control system (computer + drive controller) issues commands to the first servo motor 5, the second servo motor 10, and the displacement platform 8, respectively, causing the displacement platform 8 and the piezoelectric deflector 12 to be coarsely adjusted to their theoretical set angles under the drive of the first servo motor 5 and the second servo motor 10. The displacement platform 8, driven by a stepper motor, coarsely adjusts the observation camera 7 and the telecentric lens 9 to their theoretical set positions. Since errors may exist in the installation position of the printhead and the rotation of the lead screw in the drive assembly of the servo motor and the displacement platform 8, fine adjustments to the rotation system and the focusing system are also required (e.g., Figure 7 (as shown)

[0065] (1) Fine-tune the first servo 5 and the second servo 10:

[0066] like Figure 5 As shown, the observation camera 7 is activated and LED pulse sequence 1 is triggered. When the observation camera 7 is triggered, the print head is triggered and ejects within the trigger time range of the observation camera 7, simultaneously generating a light source trigger waveform. The observation camera 7 takes a picture, and the captured image is analyzed to determine the position of the print head nozzle and its lower area within the captured image. If it is not located at the set position on the left side of the captured image, the rotating platform in the first servo motor 5 and the second servo motor 10 is controlled to perform repeated fine adjustments. Each adjustment triggers LED pulse sequence 1, and the observation camera 7 takes a picture. The judgment is made based on the captured photos until the print head nozzle is located at the set position on the left side of the image in the captured photo. At this point, the fine adjustments end, and the rotating platforms of the first servo motor 5 and the second servo motor 10 are locked.

[0067] (2) Fine-tuning the displacement system:

[0068] The observation camera 7 is activated and LED light pulse sequence 1 is triggered to take a picture. The edge information of the captured picture is continuously analyzed to determine whether the edges are sharp, thus determining whether the telecentric lens 9 has completed focusing. If the edge sharpness of the picture does not meet the requirements, it means that the telecentric lens 9 has not completed focusing. The control system then sends a focusing command to the displacement platform 8, which moves to change the distance between the telecentric lens 9 and the observed nozzle. After each adjustment, LED pulse sequence 1 is triggered, the observation camera 7 takes a picture, and the captured image is continuously analyzed to determine whether focusing is complete. If the requirements are not met, the control system continues to send focusing commands to the displacement platform 8 until the focusing requirements are met. After this, the fine adjustment ends, and the displacement platform 8 is locked.

[0069] The simplest and most direct method for analyzing the edge information of the captured photos to determine whether the edges are clean, and thus whether the telecentric lens 9 has completed focusing, is as follows:

[0070] The image is binarized. By acquiring the image multiple times, the trend of the proportion of black area in the whole image is compared. When the proportion of black area changes from less to more and then back to less, the position of telecentric lens 9 when the proportion of black area is at the critical value of change is the focus. At this time, telecentric lens 9 is focused.

[0071] After the above fine-tuning operations, the position of observation camera 7 has been adjusted and is now in the optimal observation position, so observation can be carried out.

[0072] like Figure 6 ,8 As shown, when the observation camera is triggered, the control system (computer + drive controller) controls the observed nozzle to start operating. The nozzle generates a droplet at a synchronous or slightly slower speed. Subsequently, the LED light pulse sequence 2 and the piezoelectric deflector 12 (galvanometer system) are triggered simultaneously, causing them to operate at the same frequency and continuously. That is, for each LED light pulse emitted by the control system, the piezoelectric deflector 12 deflects rapidly by a deflection angle α in sync with the LED flash. It is proposed that within one exposure time range of the observation camera 7, the LED flash light pulse is triggered five times, and the piezoelectric deflector 12 deflects five times simultaneously (the number of deflections can be adjusted in other embodiments, but it should be at least three times. The upper limit of the number of deflections is related to the droplet diameter. While ensuring droplet separation, more deflections result in a smoother trajectory, but this leads to a decrease in observation efficiency. Currently, five deflections are the optimal choice). This means that five states of a droplet formation process are displayed in one photograph. After the five triggers are completed, a stop operation command is sent to the observation camera 7, the LED light pulses, and the piezoelectric deflector 12.

[0073] During the observation period, it is also necessary to determine whether the nozzle is working properly. The specific method is as follows:

[0074] By setting a brightness threshold for the acquired image and binarizing it, the presence of droplet images larger than a set pixel size in the image area is observed to determine whether the nozzle is working properly. If such droplets are present, the droplets are considered to be ejected normally. If the nozzle is working properly, the acquired image is analyzed and droplet features are extracted to obtain the relevant motion parameters of the nozzle droplet formation process. If the acquired image is abnormal, the fault in the nozzle needs to be identified and resolved before the nozzle can restart.

[0075] Repeat the above observation steps until you obtain an image of the droplet formation process.

[0076] After observation by one nozzle (either circuit printing nozzle 2 or structure printing nozzle 3, which alternate during actual operation), the control system switches the printing nozzle to the working position. Because the observed object and its position change, refocusing is required. All systems reset. The first servo motor 5 and the displacement platform 8 coarsely adjust the observation camera 7 to the observation position, and the second servo motor 10 coarsely adjusts the piezoelectric deflector 12 to the observation position. The first servo motor 5 rotates for fine adjustment, moving the observation camera 7 to a reasonable observation angle before stopping. The second servo motor 10 finely adjusts the piezoelectric deflector 12 to a suitable reflection position before stopping and locking. The displacement platform 8 finely adjusts the distance between the observation camera 7, the telecentric lens 9, and the nozzle to within the specified object distance range, meeting the focusing requirements before stopping and locking. After the observation camera 7 is properly positioned, the formal observation phase begins, repeating the above observation actions to obtain the droplet formation image of the second nozzle.

Claims

1. A multi-jet single droplet real-time observation apparatus, characterized by: Includes a first servo motor, a second servo motor, a displacement platform, an observation camera, a lens, a piezoelectric deflector, an LED flash, and a control system; The observation camera is mounted on the displacement platform and observes through the lens; the displacement platform is used to provide linear motion for the observation camera and the lens to achieve focusing. The displacement platform is mounted on the first servo motor, which is used to provide rotational motion to the observation camera and lens, causing them to rotate to a specified observation angle. The piezoelectric deflector is mounted on the second servo motor, which provides rotational motion to the piezoelectric deflector so that it rotates to a specified optical path refraction position, thereby achieving optical path adjustment. The LED flash is mounted on the side wall of the lens barrel, and the outgoing light path of the LED flash is parallel to the optical axis of the lens; The positional relationship between the first servo motor and the second servo motor satisfies the following condition: the two work together to form the optical path of LED flash - piezoelectric deflection mirror - currently working print head - piezoelectric deflection mirror - lens - observation camera; The control system is used to control the operation of the first servo motor, the second servo motor, the displacement platform, the observation camera, the piezoelectric deflector and the LED flash; The LED flash is controlled to turn on and off by the control system and is triggered simultaneously with the printhead of the printer that is currently in operation, and flashes at fixed frequency intervals; the relationship between the droplet images captured by the observation camera and the time sequence can be established by the switching sequence of the LED flash; During each shooting session of the observation camera, the piezoelectric deflector and the LED flash move in sync and repeatedly. Each change in the position of the piezoelectric deflector causes a shift in the droplet image, separating the overlapping parts of the droplet images at adjacent moments. This allows the observation camera to obtain images of the same droplet at multiple moments in a single shot.

2. The multiple-jet single-droplet real-time observation apparatus according to claim 1, wherein: The lens in question is a telecentric lens.

3. The multi-jet single droplet real-time observation apparatus according to claim 1 or 2, characterized by: Both the first and second servos are servos capable of rotating 360°.

4. The multiple-jet single-droplet real-time observation apparatus according to claim 3, wherein the plurality of nozzles are arranged in a line. 5 The LED flashlight is a fast-response LED.

5. The multiple-jet single-droplet real-time observation apparatus according to claim 4, wherein: Both the first and second servos are mounted on the 3D printer's work plate, which serves as a reference.

6. The multiple-jet single-droplet real-time observation apparatus according to claim 5, wherein: The control system is developed based on PLC.

7. A method for real-time observation of multiple-jet single droplets using the multiple-jet single droplet real-time observation apparatus according to any one of claims 1 to 6, characterized by, Includes the following steps: Step 1: Focus; The control system controls the rotation of the first and second servo motors to form the optical path from LED flash to piezoelectric deflector to the print head to be used, then to the lens and finally to the observation camera. The control system controls the movement of the displacement platform until the image from the observation camera is clear and the focus is achieved; Step 2: Take the photo; The control system triggers the observation camera. During each shooting session, the piezoelectric deflector and LED flash are controlled to move in sync and continuously multiple times. In this way, images of the same droplet at multiple moments can be obtained in each shooting session.

8. A multi-jet 3D printing system with liquid droplet real-time observation function, comprising a plurality of printing jets, a motion slide for driving the printing jets to move; characterized in that: It also includes the multi-nozzle single droplet real-time observation device according to any one of claims 1-6; the control system in the multi-nozzle single droplet real-time observation device is further used to switch the printing nozzles to work alternately; the multi-nozzle single droplet real-time observation device is used to acquire droplet images generated by the currently working printing nozzle among the multiple printing nozzles.

Images