A high-precision airflow-assisted electrohydrodynamic contour printing device

Abstract

This invention discloses a high-precision airflow-assisted electrohydrodynamic conformal printing device, belonging to the field of electrohydrodynamic inkjet printing technology. The device includes a printhead system, which comprises a printhead module, an airflow assist system, and an electrical signal supply section. The airflow assist system is symmetrically arranged around the central axis of the printhead module. The printhead module is connected to the electrical signal supply section. The printhead module includes a nozzle. The airflow assist system includes a gas buffer chamber, vent pipes, a conical chamber, and air pipes. The gas buffer chamber is located above the conical chamber. The gas buffer chamber is arranged in a ring around the nozzle. Several vent pipes are located below the gas buffer chamber. The inlet and outlet ends of the vent pipes are connected to the outlet of the gas buffer chamber and the conical chamber, respectively. The air pipes are located below the conical chamber and coaxially arranged around the nozzle, forming an airflow channel between the air pipes and the nozzle.

Description

Technical Field

[0001] This invention belongs to the field of electrohydrodynamic inkjet printing technology, specifically relating to a high-precision airflow-assisted electrohydrodynamic conformal printing device. Background Technology

[0002] Three-dimensional curved surface electronics represent a trend in the microelectronics industry. By directly molding circuits onto the surface of a product structure, it not only achieves structural-functional integration but also enables miniaturization, intelligence, and lightweighting of electronic products. Conformal curved electronics possess the unique ability to coexist with complex curved surfaces while retaining the electronic functions of planar integrated circuit technology. This allows electronic devices to be applied more broadly in complex and ever-changing scenarios, holding significant importance for functional integration in areas such as health monitoring, environmental sensing, and frequency-selective surfaces. Examples include intelligent sensing skins for aircraft, stealth electromagnetic functional structures, and conformal curved antennas. Currently, the manufacturing technologies for curved electronics can be broadly categorized into three types: extrusion 3D printing, laser direct writing, and inkjet printing. Extrusion-based 3D printing is simple in principle, economical, and allows for a wide range of material viscosities, but it suffers from slow printing speeds, poor resolution, and the inability to directly print circuits on highly curved surfaces. Laser direct writing can etch circuits by modifying the substrate material, but this process has requirements for the substrate material, a narrow application range, and is not environmentally friendly. Inkjet printing is a green additive manufacturing technology that can directly deposit functional inks onto a substrate to build images, offering advantages such as material savings, environmental friendliness, and ease of operation, and has been widely used in recent years. However, traditional inkjet printing technology still suffers from drawbacks such as low printing resolution (≥20μm), droplet size limited by nozzle diameter (droplet diameter ≈ nozzle diameter × 2), easy nozzle clogging, and complex nozzle manufacturing processes. Electrohydrodynamic inkjet printing is a novel inkjet printing method with submicron resolution and wide ink viscosity compatibility, providing a good solution for high-resolution deposition of high-viscosity materials.

[0003] Unlike traditional inkjet printing, which uses an "extrusion" method, computer fluid dynamics printing uses an electric field to drive and "pull" an extremely fine jet from the tip of a formed "Taylor cone." This offers advantages such as easy ejection of particles or polymer solutions without clogging, and the ability to print high-viscosity (≤10000 mPa·s) conductive liquids. Its printing resolution is not directly affected by the nozzle diameter, achieving sub-micron resolution (>0.3 μm), making it suitable for curved electronic circuits, solar cells, and bio-functional devices. However, existing electrofluid printing methods are not suitable for substrates with large curvatures. Furthermore, the influence of non-planar substrates on the electric field, as well as charge accumulation and polarization issues on insulating substrates, result in poor printing performance on non-planar and insulating substrates. This is because the electric field on curved surfaces interferes with the electrofluid printing jet, thus affecting print quality. Specifically, when the printhead prints on surfaces with different curvatures, it cannot print according to the shape of the surface, causing the jet direction to be not vertically downward, but rather "pulled" by the lateral electric field. This causes two problems for printing: (1) Because the jet is "pulled" by the lateral electric field, the landing point of the jet is inconsistent with the actual movement trajectory of the nozzle, affecting the positioning accuracy of the print; (2) The normal distance between the nozzle and the substrate will decrease, while the voltage between the nozzle and the substrate is fixed, which means that the interelectrode field strength will increase, resulting in turbulence in the electrohydraulic printing jet. Therefore, when printing on non-planar substrates, it is difficult to keep the relative vertical height between the printhead and the substrate surface constant. The change in the relative vertical height will cause the change in the electric field strength at the printhead tip, which is a key factor in controlling droplet ejection. After the electric field distribution on the curved surface changes, the direction of the electric field between the printhead and the substrate will deviate with the change of the substrate surface, affecting the uniformity of the applied electric field. Moreover, the range of variation of the height of the existing printhead from the non-planar substrate is limited, and a slightly higher printing height will lead to a deterioration in the printing effect.

[0004] In electrohydraulic inkjet printing, the printed jet has a high charge density, and its movement is primarily controlled by an electric field. During printing, due to the low conductivity of the insulating material, the charge carried by the deposited droplets cannot be eliminated through the substrate. Charge accumulation and polarization on the insulating substrate, as well as the irregular surface of the curved substrate, all affect the electric field at the nozzle. Charge accumulation and substrate polarization affect the electric field around the printhead or repel subsequent printed droplets, reducing the stability and accuracy of electrohydraulic inkjet printing, and even causing printing failure. Therefore, existing printing methods cannot form a stable electric field, failing to meet the uniformity and stability requirements of conformal printing of curved circuits. Ensuring the stability of the electric field distribution and the forces acting on the charged jet in the electrohydraulic inkjet printing space is crucial for improving printing performance. Furthermore, the printing efficiency of electrohydraulic inkjet printing hinders its application in the widespread rapid prototyping field, mainly because the size of the droplets or jet exhibits a strong dependence on the flow rate. Low Reynolds numbers are constrained by the requirement that the total flow rate does not increase beyond a threshold to ensure that inertial forces remain negligible. Furthermore, due to the inherent limitations of the electric fluid itself, it is difficult to print materials that are insensitive to electric fields, such as insulating materials between multilayer circuits, within a given target droplet size.

[0005] In summary, existing electrohydraulic inkjet printing systems suffer from several drawbacks, including the inability to directly print on insulating substrates, the inability to perform conformal printing on complex curved surfaces, low printing efficiency, and the inability to print materials insensitive to electric fields. These issues have reduced printing accuracy and stability, and in some cases, rendered printing impossible, severely limiting the application scope of electrohydraulic inkjet printing. Therefore, given the urgent need for conformal printing in curved functional electronic devices, designing a high-precision electrohydraulic conformal printing system for complex hard curved surfaces to address these problems is of great significance. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies in meeting the requirements of conformal printing for curved functional electronic devices, the present invention aims to provide a high-precision airflow-assisted conformal electrohydraulic printing device. By applying an auxiliary airflow between the printing nozzle and the annular electrode, the airflow changes the direction of the jet ejected from the nozzle, which can both guide the jet for precise positioning and constrain the airflow, breaking through the limitation of the limited distance between the nozzle and the substrate and improving the accuracy of electrohydraulic printing. By focusing the airflow, materials that are not sensitive to electric fields can be printed more widely, breaking through the limitation of the printing material's own conductivity and broadening the application range of printing materials. By using gas focusing to assist electrohydraulic printing, fluids with higher Reynolds numbers can be ejected, eliminating the strong dependence of droplet or jet size on flow rate and improving ejection efficiency. The gas buffer chamber and conical airflow channel achieve buffering and focusing of the airflow, improving printing quality and meeting the requirements of conformal printing for curved functional electronic devices.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] This invention provides a high-precision airflow-assisted electrohydrodynamic conformal printing device, including a printhead system. The printhead system includes a printhead module, an airflow assist system, and an electrical signal supply section. The airflow assist system is symmetrically arranged around the central axis of the printhead module. The printhead module is connected to the electrical signal supply section.

[0009] The nozzle module includes a nozzle; the airflow assist system includes a gas buffer chamber, an air vent, a conical chamber, and an air pipe;

[0010] The gas buffer chamber is positioned above the conical chamber; the gas buffer chamber is arranged in a ring around the nozzle, and several vent pipes are positioned below the gas buffer chamber. The inlet and outlet ends of the vent pipes are connected to the outlet of the gas buffer chamber and the conical chamber, respectively. The vent pipes are positioned below the conical chamber and are coaxially positioned around the nozzle, forming an airflow channel between the vent pipes and the nozzle.

[0011] In practice, the bottom end of the nozzle is located above the bottom end of the air pipe and maintains a fixed distance.

[0012] In practice, the nozzle module also includes an annular electrode; the annular electrode is coaxially disposed below the nozzle and the air pipe.

[0013] In the specific implementation process, an air inlet is provided on the side of the gas buffer chamber, and the air inlet is connected to a pressurized air source.

[0014] In the specific implementation process, the inner wall at the outlet of the trachea contracts towards the center;

[0015] The airflow flowing out of the trachea forms an airflow sleeve, which surrounds the ink droplet.

[0016] In practice, the electrical signal supply section includes a high-voltage power supply and a high-voltage amplifier.

[0017] The high-voltage power supply and high-voltage amplifier are used to apply voltage to the inner wall of the nozzle and the annular electrode. The nozzle is connected to the positive high voltage, the annular electrode is connected to the positive low voltage, and the negative high voltage is connected to the worktable.

[0018] In the specific implementation process, the electrical signal supply part also includes a flow supply module and an air pressure balance system that are connected to each other. The flow supply module is used to adjust the flow rate of ink ejected from the nozzle.

[0019] In the specific implementation process, a vision system is also included, which includes a positioning camera and an observation camera. The positioning camera is set perpendicular to the substrate, and the observation camera is set aligned with the nozzle. The observation camera is used to observe the Taylor cone of the printed jet in real time during the printing process, and the positioning camera is used for real-time accurate positioning between the curved substrate and the nozzle.

[0020] In the specific implementation process, it also includes a five-axis motion system, which includes a support column, a Z-axis group is provided inside the support column, a support plate is provided between the two Z-axis groups, a connecting base plate is provided on the support plate, and a nozzle module is provided on the connecting base plate.

[0021] A worktable is located directly below the nozzle module, a two-dimensional rotary table is located below the worktable, a Y-axis group is located below the two-dimensional rotary table, an X-axis group is located below the Y-axis group, and a sliding table is located between the Y-axis group and the X-axis group.

[0022] In specific implementation, the two-dimensional rotary table includes a first rotating part and a second rotating part;

[0023] The second rotating part is mounted on the platform of the first rotating part;

[0024] The first rotating part rotates around the Y-axis, and the second rotating part rotates around the normal direction of the plane perpendicular to the first rotating part.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention provides a high-precision airflow-assisted electrohydraulic conformal printing device. The auxiliary airflow provided by the airflow assistance system can change the direction of the jet ejected from the nozzle, guiding the jet for precise positioning and constraining the airflow. This overcomes the limitation of the limited distance between the nozzle and the substrate, improving the accuracy of electrohydraulic printing. By focusing the auxiliary airflow, materials insensitive to electric fields can be printed more widely, solving the problem that simple electrohydraulic printing cannot meet the printing requirements of electrically insensitive materials. This overcomes the limitation of printing materials being limited by their inherent conductivity, broadening the application range of printing materials. Furthermore, by using gas focusing to assist electrohydraulic printing, higher Reynolds number fluids can be ejected, eliminating the strong dependence of droplet or jet size on flow velocity and improving ejection efficiency.

[0027] Furthermore, in this invention, an airflow is introduced between the nozzle and the annular electrode. The electrical signal section applies an alternating voltage to the ink in the ink tank and the electrode ring. The positive voltage applied to the nozzle is higher than the positive voltage applied to the electrode ring. The ground potential of the printing substrate is zero. Through multi-level voltage control, a stable electric field required for electrofluid printing is formed between the nozzle and the substrate. Under the action of airflow and electric field force, the charged ink is sprayed from the nozzle onto the insulating substrate with high resolution. The annular electrode significantly reduces the voltage between the electrode ring and the insulating substrate. The alternating voltage solves the problem of the influence of the polarization of the insulating substrate on electrofluid printing.

[0028] Furthermore, the present invention includes an observation camera in the vision system for real-time observation of the Taylor cone of the electro-inkjet printing jet during the printing process, and a positioning camera for real-time precise positioning between the curved substrate and the nozzle. A real-time monitoring system for the printing process is established, enabling monitoring of the jet morphology throughout the entire printing process. By observing the liquid state at the nozzle tail in real time, printing process parameters can be adjusted promptly, thereby printing the required high-quality, high-precision curved circuit.

[0029] Furthermore, the present invention enables the five-axis linkage of the five-axis motion system to achieve conformal printing motion of the electrofluid on any complex curved surface, breaking through the limitation of the non-planar substrate shape on the uniformity of the applied electric field and solving the problem of interference of the curved surface electric field on the electrofluid printing jet. Attached Figure Description

[0030] Figure 1 A schematic diagram of the airflow-assisted electrofluid conformal printing principle constructed according to a preferred embodiment of the present invention;

[0031] Figure 2 A schematic diagram illustrating the airflow structure principle of the airflow-assisted electrofluid conformal printing nozzle constructed according to a preferred embodiment of the present invention;

[0032] Figure 3 A schematic diagram illustrating the motion relationship principle of the airflow-assisted electrofluid conformal printing device constructed according to a preferred embodiment of the present invention;

[0033] Figure 4 A front view of the structure of the airflow-assisted electrofluid conformal printing device constructed according to a preferred embodiment of the present invention;

[0034] Figure 5 A schematic left view of the airflow-assisted electrofluid conformal printing device constructed according to a preferred embodiment of the present invention;

[0035] Figure 6 A side view schematic diagram of an airflow-assisted electrofluid conformal printing device constructed according to a preferred embodiment of the present invention;

[0036] Figure 7This is a schematic diagram of a printhead constructed according to a preferred embodiment of the present invention for printing a curved conformal circuit on a non-planar insulating substrate.

[0037] Among them, 1-Z-axis drive motor; 2-observation camera; 3-support plate; 4-C-axis drive motor; 5-moving slide; 6-X-axis motion axis group; 7-X-axis drive motor; 8-nozzle module; 9-positioning camera; 10-connecting base plate; 11-rib plate; 12-second rotating part; 13-B-axis drive motor; 14-Y-axis motion axis group; 15-first rotating part; 16-coupling; 17-X-axis lead screw; 18-two-dimensional rotary table; 19-Y-axis drive motor; 20-support column; 21-Z-axis lead screw; 22- Z-axis motion assembly; 23-flow pump; 24-infusion tube; 25-high voltage amplifier; 26-high voltage power supply; 27-host computer; 28-worktable; 29-substrate; 30-jet; 31-ring electrode; 32-conical chamber; 33-air inlet; 34-ink tank; 35-gas buffer chamber; 36-nozzle; 37-air pipe; 38-Taylor cone; 39-linear movement along the Z-axis; 40-rotational movement along the C-axis; 41-linear movement along the Y-axis; 42-linear movement along the X-axis; 43-rotational movement along the B-axis. Detailed Implementation

[0038] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of the present invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the present invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0039] This invention provides a high-precision airflow-assisted electrohydrodynamic conformal printing device, comprising a printhead system consisting of a printhead module 8, an airflow-assisted system, and an electrical signal supply unit, a five-axis motion system, and a vision system.

[0040] The five-axis motion system, or motion module, includes motion modules and a motion control system. The five-axis motion system consists of three translation axes (X, Y, Z) and two rotation axes (B, C), where axes B and C rotate around the Y and Z axes, respectively. The X, Y, and Z motion modules and the B and C rotation axes are driven by five motor modules. Specifically, the five-axis motion system includes a vertical support column 20, within which a Z-axis motion axis group 22 is installed. Support plates 3 are arranged on the two Z-axis motion axis groups 22, and connecting base plates 10 are arranged on the support plates 3. A nozzle module 8 is mounted on the connecting base plate 10 and moves in the Z-direction (linearly along the Z-axis direction 39) along with the connecting base plate 10. A worktable 28 is located directly below the nozzle module 8, mounted on a two-dimensional rotary table 18. The first rotating part 15 (B rotation module) rotates around the Y-axis (e.g., ...). Figure 3 As shown in the trajectory of rotational motion 43 in direction B), the second rotating part 12 (C rotating module) is mounted on the platform of the first rotating part 15, and the second rotating part 12 rotates about the normal direction of the plane perpendicular to the first rotating part 15 (as shown in the trajectory of rotational motion 43 in direction B). Figure 3 (The trajectory of the rotational motion 40 in the C direction is shown); the two-dimensional rotary table 18 is mounted on the Y-axis group 14, which is mounted on the X-axis group 6 via the sliding table 5. The two-dimensional rotary table 18 as a whole moves in translational motion along the X and Y directions simultaneously with the X and Y axis groups. Through the relative movement of the worktable 28 and the nozzle module 8, three translational motions (X, Y, Z) and two rotational motions (B, C) are realized. Through five-axis linkage, the nozzle can follow the shape of the complex curved surface. The nozzle 36 can reach any curved surface position on the printed entity and maintain a reasonable printing distance, realizing the basic motion requirements of three-dimensional printing and ensuring the uniformity of the electric field applied to the nozzle.

[0041] A rib plate 11 is provided below the connecting base plate 10. The coupling 16 is a commonly used component in mechanical devices, mainly used to connect shafts to transmit motion and torque, and can also be used as a safety device.

[0042] The printhead system includes a printhead module 8, an airflow assist system, and an electrical signal supply section. The printhead module 8 mainly includes an ink tank 34, a nozzle 36, and an annular electrode 31. The printhead module 8 is mounted on a connecting base plate 10. The connecting base plate 10 moves vertically up and down with the Z-axis motion assembly 22 to achieve the Z-axis freedom of the printhead. The nozzle 36 is located below the ink tank 34. High-frequency stable ink supply is achieved by controlling the air pressure in the air pressure valve. The airflow assist system is integrated outside the nozzle 36 and is an axisymmetric structure about the central axis of the nozzle 36. It mainly includes a gas buffer chamber 35, a conical chamber 32, an air vent, and an air pipe 37, which are coaxially integrated into the printhead module. Below the nozzle 36, the bottom end of the nozzle 36 is located above the bottom end of the airflow assist system and maintains a fixed distance. There is an air inlet 33 on the side of the gas buffer chamber 35. The air inlet 33 is connected to the pressurized air source. The gas from the air source is homogenized by the annular gas buffer chamber 35 and flows into the conical chamber 32 and converges into the air pipe 37. The air pipe 37 is coaxially installed outside the nozzle 36. There is an air outlet at the bottom end of the conical chamber 32 that is coaxial with the nozzle 36. The airflow flows in from the cylindrical area between the nozzle 36 and the air pipe 37 and finally focuses onto the jet 30. It gathers at the air outlet below the nozzle 36, and the gas-liquid and electro-hydraulic jets are ejected from the air outlet. Specifically, a gas buffer chamber 35 is arranged in a ring around the nozzle 36. Several air vents are located below the gas buffer chamber 35. The inlet and outlet ends of the air vents are connected to the outlet of the gas buffer chamber 35 and the conical chamber 32, respectively. An air pipe 37 is located below the conical chamber 32 and is coaxially arranged around the nozzle 36, forming an airflow channel between the air pipe 37 and the nozzle 36. The annular electrode 31 is located at the lowest end of the airflow assist system. The electrical signal supply section includes a high-voltage power supply 26 and a high-voltage amplifier 25. The high-voltage power supply 26 and the high-voltage amplifier 25 apply voltage to the inner wall of the nozzle 36 and the annular electrode 31. The nozzle 36 is connected to the positive high voltage, the annular electrode 31 is connected to the positive low voltage, and the worktable 28 is connected to the negative high voltage. This creates a gradient potential difference on the ink, the annular electrode 31, and the substrate 29 to be printed, thereby maintaining the stability of the electric field of the substrate 29 during complex posture changes.

[0043] In the specific implementation process, the nozzle 36 is placed coaxially above the air outlet, and the distance between the nozzle 36 and the air outlet is kept fixed. The pressure difference of the air on both sides of the air outlet causes a violently contracting airflow to be formed between the small hole and the nozzle 36. The airflow plays a focusing role on the liquid flowing out of the nozzle 36.

[0044] The advantage lies in the fact that the nozzle 36 is coaxially positioned above a small orifice, i.e., the air outlet. The pressure difference of the air on both sides of the orifice creates a rapidly contracting airflow between the orifice and the nozzle 36. This airflow focuses the electrically insensitive liquid flowing out of the nozzle 36, causing the liquid to form a cone shape at the tip of the nozzle 36 (i.e., at the orifice), similar to the Taylor cone shape produced in electrohydraulic inkjet printing. After passing through the orifice, the liquid forms a fine jet 30 at the end of the cone. As the disturbance increases, the jet breaks into droplets after traveling a certain distance. Similar to electrohydraulic inkjet printing, the size of the jet generated by flow focusing is also much smaller than the size of the nozzle 36, and the size of the formed droplets is on the micro-nano scale.

[0045] The deposition behavior of the jet 30 in electrohydraulic inkjet printing is also affected by the surrounding flow field, inevitably leading to jet adhesion. Applying airflow around the jet is an important auxiliary method in electrohydraulic inkjet printing. Airflow-assisted electrohydraulic inkjet printing involves applying a stable airflow in the same direction as the jet, coaxially between the nozzle 36 and the air pipe 37. The auxiliary airflow provides external tensile force and constraint to the charged jet. The airflow converges around the electrohydraulic jet, giving it better focusing and a better constraint effect on the jet, which can overcome the interference of residual charge and high-speed moving substrate.

[0046] In the specific implementation process, the air pipe 37 is coaxially installed in the airflow-assisted electro-hydraulic nozzle outside the solution nozzle 36. The auxiliary airflow is uniformly and stably introduced between the air pipe 37 and the nozzle 36. The airflow changes the movement direction of the jet ejected from the nozzle 36. The airflow converges around the electro-hydraulic jet and constrains the jet, guiding the jet to be accurately printed onto the target substrate located below the printing nozzle and electrode.

[0047] The airflow enters from the cylindrical area between the nozzle 36 and the air pipe 37, and gathers at the outlet of the air pipe 37 below the nozzle 36 at a relatively high speed. As the airflow develops, its speed decreases after contacting the substrate and it diffuses in all directions, eventually settling into the surrounding environment.

[0048] The dual manufacturing process of gas-fluid and electro-fluid involves the following steps: If only the EHD method is used, the switch is turned on to prevent compressed air from entering the conical chamber 32. A strong electric field is formed between the nozzle 36 and the substrate 29, and the liquid can only be drawn out of the nozzle 36 by electricity. If only the gas-fluid focusing jet method is used, the switch is turned off to remove the electric field in the chamber. Pressurized gas enters the ink tank 34, forcing the ink chamber to form a pointed cone similar to a Taylor cone 38. Then, accompanied by flowing air, the liquid jet is ejected from the orifice.

[0049] Specifically, a dual manufacturing process combining two methods is proposed, using a pneumatic-fluid-assisted method as a complementary approach to address the inherent limitations of electrohydraulic inkjet printing. When the ink is an electric field-sensitive material, a pneumatic-fluid-assisted electrohydraulic inkjet printing method is used. Compressed air is allowed to enter the conical chamber 32, a high positive voltage is applied to the printhead, a low positive voltage is applied to the annular electrode 31, the stage 28 is grounded, and a strong electric field is formed between the nozzle 36 and the stage 28. The liquid is drawn out of the nozzle 36 by electricity under the assistance of the pneumatic field. When the ink is an electric field-insensitive material, a pneumatic-fluid focusing jet method is used. The switch is turned off to remove the electric field between the nozzle 36 and the stage 28. The stage 28 does not need to be grounded. At the same time, the collecting substrate can be any curved or non-curved substrate made of insulating material. Pressurized gas enters the conical chamber 32, forcing the ink cavity to form a pointed cone similar to a Taylor cone. Then, accompanied by flowing air, the liquid jet is ejected from the orifice.

[0050] In the specific implementation process, the annular electrode 31 is coaxial with the nozzle 36 to reduce the voltage between the annular electrode 31 and the stage 28, thereby reducing the impact of substrate 29 polarization on the printing effect; the annular electrode 31 is also used to focus the jet to suppress satellite droplets.

[0051] In the specific implementation process, the grounding of the worktable 28 makes the potential of the curved substrate to be printed zero. The voltage applied to the ink is higher than the voltage applied to the annular electrode 31, thereby forming a gradient potential difference on the ink, the annular electrode 31 and the substrate to be printed. This ensures the stability of the electric field during the change of the posture of the curved substrate to be printed, and the liquid is accurately sprayed from the tip of the cone onto the curved substrate.

[0052] In practical implementation, the high-voltage power supply 26 generates alternating positive and negative voltages. The voltage signal is amplified 1000 times by the high-voltage amplifier 25 and applied between the nozzle 36 and the substrate 29 to achieve the high-voltage range required for electro-ink printing. Different electrical signals can cause the nozzle 36 to generate electro-hydraulic printing jets of different shapes. The high-voltage power supply 26 and the high-voltage amplifier 25 provide an alternating positive and negative electric field for printing. By applying alternating positive and negative AC voltage signals to the printhead, the charge properties of the droplets printed on the insulating substrate are also alternating between positive and negative. By neutralizing the charge carried by the droplets, the influence of charge on the jet is reduced, thereby solving the printing instability problem caused by any charge accumulation effect on the insulating substrate.

[0053] An annular electrode 31, coaxial with the nozzle 36, is added between the nozzle 36 and the substrate 29. The nozzle 36 and the annular electrode 31 are controlled by multi-level voltage, with the voltage of the annular electrode 31 being lower than that of the nozzle 36. This creates a gradient potential difference between the printhead and the annular electrode 31, and between the annular electrode 31 and the substrate 29 being printed. This significantly reduces the voltage between the annular electrode 31 and the substrate 29, thus reducing the impact of substrate 29 polarization on printing.

[0054] Furthermore, the precision printhead includes a matching high-precision pressure balancing system and electrical control circuitry, which is used to drive the ink supply of the nano-silver conductive solution.

[0055] In the specific implementation process, the electrical signal supply section also includes a flow supply module, which is used to adjust the flow rate of ink ejected from the nozzle, such as the device flow pump 23.

[0056] Its advantage is that the flow supply module is driven by the air pressure balance system. The automatic compensation function of the balance system can automatically adjust the air pressure according to the amount of ink in the ink tank 34 to prevent the ink "needle crawling" phenomenon caused by capillary effect, so as to realize the quantitative and stable supply of functional materials throughout the printing process.

[0057] Furthermore, a central pneumatic compressor is used as the compressed air source, capable of providing compressed air up to 125 psi. A custom regulator setting with 2 psi resolution is used to control the pressure air delivered to the pressurization chamber.

[0058] Furthermore, in the airflow field at the nozzle, the contour shape of the constricted portion of the inner wall of the air tube 37 and the position of the outlet relative to the tip of the nozzle 36 are key factors affecting the airflow field. The nozzle 36 of the flow focusing micro-injection of the present invention is manufactured by flame polishing, resulting in a smooth glass air tube surface. The roughness of the orifice surface is less than the thickness of the boundary layer on the orifice surface, which not only discourages the formation of turbulence and backflow but also facilitates the removal of impurities and prevents air tube blockage.

[0059] Furthermore, the nozzle 36 is treated with a hydrophobic coating to prevent liquid from wetting the nozzle edge and to ensure a repeatable conical base for repeatable conical jet transitions.

[0060] The vision system includes an observation camera 2 and a positioning camera 9. The observation camera 2 is aligned with the nozzle 36 for real-time observation of the Taylor cone 38 of the EHD printing jet during the printing process. The positioning camera 9 is aligned with the curved surface for real-time and precise positioning between the substrate 29 and the nozzle 36. This invention establishes a real-time monitoring system for the printing process, enabling monitoring of the jet morphology throughout the entire printing process. By observing the liquid state at the nozzle tail in real time, printing process parameters can be adjusted promptly, thereby printing the required high-quality, high-precision curved surface circuits.

[0061] This invention effectively solves the current technical challenge of directly manufacturing high-precision circuits on non-planar substrates in the printed electronics field. It enables automated, precise, environmentally friendly, and highly efficient direct manufacturing of arbitrarily complex curved conformal circuits without the need for additional transfer, deformation, or other auxiliary processes. It utilizes a pneumatic fluid-assisted method as a complementary approach to overcome the inherent limitations of electrofluid printing, representing a dual manufacturing process combining two methods. When the printing material is an electric field-sensitive conductive ink, the pneumatic fluid is applied concurrently to the electrofluid jet as an auxiliary process; when the printing material is insensitive to an electric field, pneumatic fluid focusing jetting is the primary process for focusing and ejecting the droplets. This invention enables the direct conformal manufacturing of curved circuits on the surface of products with arbitrarily complex shapes, overcoming the limitations of traditional printing processes in terms of printing conditions and resolution. It also solves the problem of high-viscosity liquids clogging the nozzle, offering advantages such as simple process, high resolution, high efficiency, high reliability, and low cost, meeting the flexibility requirements for direct manufacturing of arbitrarily curved conformal circuits.

[0062] The airflow focusing assisted electrohydrodynamic printing method used in this invention eliminates the limitations imposed by substrate material and shape on printing in electrohydrodynamic inkjet printing, and realizes accurate and stable printing of electrohydrodynamic inkjet printing on insulating and non-planar substrates, greatly expanding the application range of electrohydrodynamic inkjet printing.

[0063] In a further step of the above technical solution, the airflow assist system is made of insulating material; the annular electrode 31 is made of conductive material, and the thickness of the annular electrode 31 is 0.5mm to 3mm. The axial distance between the nozzle 36 and the annular electrode 31, that is, the distance along the central axis of the airflow assist electro-hydraulic printing head, is adjusted by installing annular electrodes 31 of different thicknesses. The adjustable range of the axial distance is 0mm to 3mm.

[0064] This invention uses a high-voltage power supply 26 and a high-voltage amplifier 25 to apply a high voltage to the conductive ink, and applies a low voltage to the annular electrode 31. The worktable 28 is grounded so that the potential on the substrate 29 of the printed curved surface is zero. This forms a stable electric field that does not change with the posture movement of the printed curved surface substrate, thereby making the conductive ink at the nozzle 36 spray out smoothly, continuously spray, with high printing accuracy and good forming effect.

[0065] The electric field formed between the nozzle 36 and the annular electrode 31 has a radial component pointing towards the annular electrode. Applying an auxiliary airflow between the printing nozzle 36 and the annular electrode 31 creates a continuous microjet. This airflow alters the direction of the jet ejected from the nozzle 36, preventing the charged jet from printing onto the annular electrode 31 and guiding the jet 30 to print onto the substrate 29 located below the printing nozzle 36 and the annular electrode 31. This method eliminates the restriction that the substrate 29 must be grounded and significantly reduces the impact of changes in the relative height of the substrate 29 on the electric field strength at the nozzle tip, enabling printing on curved insulating substrates. Furthermore, applying an auxiliary airflow between the nozzle 36 and the ground electrode alters the direction of the jet 30 ejected from the nozzle 36, guiding the jet 30 to precisely print onto the substrate located below the printing nozzle and the ground electrode, eliminating the dependence of the printing behavior on the substrate's levelness and the distance between the nozzle tip and the ground electrode.

[0066] This invention utilizes airflow-assisted electrofluid printing to prepare conformal electrons on curved surfaces, reducing manufacturing costs, expanding the application range of printable materials, and improving printing accuracy. Employing a five-degree-of-freedom motion platform ensures that the normal to the surface to be printed coincides with the nozzle direction at all times. Combined with the matching of the function and parameter settings of the annular electrode 31, a stable electrofluid printing process environment is provided, guaranteeing the stable formation and maintenance of the "Taylor cone" during the electrofluid printing process. In conjunction with the printing method of this invention, conformal patterning processes for arbitrarily complex curved surfaces can be achieved. High-quality circuits and devices with high straightness, good uniformity, strong coherence, and excellent electrical performance can be directly printed, overcoming the technical bottleneck of not being able to directly manufacture high-precision conformal circuits on arbitrarily complex curved surfaces (especially concave surfaces with large curvature). This breaks the limitation of traditional curved electron preparation being restricted to simple curved surfaces or planes with small curvature, thus expanding the application range of electrofluid conformal printing technology.

[0067] This invention applies an auxiliary airflow between the print nozzle and the ground electrode. When ink is ejected, the airflow flows through a channel, forming an airflow sleeve. This airflow sleeve surrounds the ejected ink droplets, maintaining their stable shape and speed. By controlling the airflow, the ejection position and shape of the ink can be precisely controlled, thereby achieving higher resolution and higher quality printing results.

[0068] The airflow-assisted electrohydrodynamic jetting method in this invention can accelerate ink ejection speed, overcoming the strong dependence of droplet or jet size on flow rate. Low Reynolds numbers are constrained by the requirement that the total flow rate should not increase beyond a threshold; the medium-to-high Reynolds number airflow focusing method opens a new perspective for high-productivity complementarity in low Reynolds number EHD printing systems. By generating continuous microjets through co-current airflow, ink can be deposited at higher production rates, and its printing capability is not limited by ink viscosity.

[0069] This invention addresses the common problems encountered when printing on curved insulating substrates, such as the inability to generate electrofluid jets or jet turbulence due to strong electric field polarization. By improving the nozzle for curved electrofluid printing, incorporating an AC amplifier and pulse function generator, and supplemented by pneumatic fluid and alternating positive and negative electric fields, the electrofluid printing process can directly and on-demand print high-precision conformal circuits on any substrate, ensuring that the shape of the deposited droplets and the jet trajectory are unaffected by the substrate material. Pneumatic fluid-assisted electrofluid printing can also print on various types of media, including ordinary paper, photo paper, and fabric. In addition to printing conductive materials, the pneumatic fluid-assisted electrofluid printing system can also print non-conductive materials that are insensitive to electric fields.

[0070] The device described in this invention enables precise and stable printing on an insulating non-planar substrate using pneumatic fluid-assisted electrohydraulic inkjet printing compatible with various electrohydraulic inkjet printing modes, achieving three printing modes: continuous direct writing, on-demand inkjet printing, and near-field spinning.

[0071] Example

[0072] The present invention will now be described in further detail with reference to the accompanying drawings:

[0073] See Figures 1 to 7 This embodiment provides a high-precision airflow-assisted electrohydrodynamic conformal printing device, including a five-axis motion system, a printhead module 8, an airflow-assisted system, and an electrical signal supply unit, comprising a printhead system and a vision system, the details of which are as follows:

[0074] Five-axis motion system

[0075] The device described in this embodiment employs a five-axis motion system. The object to be printed, i.e., the substrate 29 to be printed, is mounted on a two-dimensional rotary table 18. The first rotating part 15 of the two-dimensional rotary table 18 can rotate around the Y-axis (e.g., ...). Figure 3 As shown in Figure 43 (rotational motion in direction B), the second rotating part 12 is mounted on the platform of the first rotating part 15, and the second rotating part 12 can rotate about the normal direction of the plane perpendicular to the first rotating part 15 (e.g., rotational motion in direction B). Figure 3(See diagram 40 for C-axis rotational motion); the two-dimensional rotary table 18 is simultaneously mounted on the movable slide 5, which performs left and right translational motion in the Y-axis, and the Y-axis motion axis group 14 is mounted on the X-axis motion axis group 6, which performs left and right translational motion in the Y-axis along with the movable slide 5; the nozzle module 8 is mounted on the connecting base plate 10, which can perform translational motion in the Y and Z axes simultaneously. Through the relative motion between the printed entity, i.e., the substrate 29, and the nozzle module 8, three translational motions are achieved: linear motion 42 along the X-axis, linear motion 41 along the Y-axis, and linear motion 39 along the Z-axis, and two rotational motions: rotational motion 43 in the B-axis and rotational motion 40 in the C-axis. This achieves a five-axis linkage motion mechanical structure, enabling the nozzle 36 in the nozzle module 8 to reach any curved surface position on the substrate 29 to be printed, while maintaining a reasonable printing distance. This allows the five-axis motion platform to achieve vertical printing of the nozzle on the curved substrate, fulfilling the basic motion requirements for three-dimensional printing.

[0076] like Figure 4 , Figure 5 and Figure 6 As shown, the X-axis drive motor 7, Y-axis drive motor 19, and Z-axis drive motor 1 receive control commands from the host computer 27. The X, Y, and Z axis drive motors are used to realize the horizontal free movement of the substrate 29 in the X, Y, and Z directions through the X-axis lead screw 17, Y-axis lead screw, Z-axis lead screw 21, and guide rails, forming the X-axis motion axis group 6, Y-axis motion axis group 14, and Z-axis motion axis group 22.

[0077] The nozzle module 8 on the connecting substrate 10 moves linearly in the Y and Z directions. The two-dimensional rotary table 18 moves linearly in the X direction along the X axis 42 and in the Y direction along the Y axis 41. The worktable 28 has mechanical clamps to fix the substrate 29 to be printed and is strongly connected to the X motion axis group 6. The B-axis drive motor 13 of the two-dimensional rotary table 18 receives the control command from the host computer 27 and drives the second rotating part 12 of the tilting action table to rotate in the B direction around the X axis 43. The C-axis drive motor 4 of the tilting action table of the two-dimensional rotary table 18 receives the command from the host computer 27 and drives the rotary action table to rotate in the C direction around the Z axis 40.

[0078] The above three linear motions and two rotational motions realize the five-axis linkage motion function, which can directly print on any complex curved surface circuit.

[0079] Nozzle system

[0080] The structure of a high-precision airflow-assisted conformal electrochemical printer differs somewhat from that of ordinary electrochemical printers. Due to the inherent limitations of electrochemical printing itself, ordinary electrochemical printers struggle to print materials insensitive to electric fields, such as insulating materials between multilayer circuits, at a given target droplet size. Furthermore, existing electrochemical printing methods suffer from limitations such as the inability to directly print on insulating substrates, the inability to conformally print on complex curved surfaces, and low printing efficiency, severely restricting the application scope of electrochemical printing technology.

[0081] Based on the above problems, the printhead system in the device provided in this embodiment includes a printhead module 8, an airflow assist system, and an electrical signal supply section. The airflow assist system is integrated inside the printhead module 8, located coaxially around the nozzle 36. The electrical signal supply section is connected to the printhead module 8 to provide the drive electrical signals required for electro-hydraulic printing. The printhead module 8 is positioned below the support plate 3 connected to the Z-axis motion assembly 22 and moves linearly 39 along the Z-axis direction with the Z-axis motion assembly 22. It includes an ink tank 34, a nozzle 36 located below the ink tank, and a coaxial auxiliary annular electrode 31 located below the nozzle 36. The annular electrode 31 is positioned at the bottom of the airflow assist system, and the annular electrode 31 and the bottom of the nozzle 36 maintain a fixed distance. The electrical signal supply section includes a high-voltage power supply 26, a high-voltage amplifier 25, and a flow pump 23. Ink in ink tank 34 is supplied to nozzle 36 via inlet tube 24 by air pump 23. High-voltage power supply 26 provides alternating voltage required for electrofluid printing to nozzle 36 and annular electrode 31. The voltage signal is amplified by high-voltage amplifier 25 and applied to nozzle 36 and annular electrode 31. Different electrical signals can cause nozzle 36 to generate electrofluid printing jets in three different modes: continuous direct writing, on-demand printing, and near-field spinning. The printhead module 8 is connected to alternating positive and negative AC voltage signals, so that the charge properties of the droplets printed on the insulating substrate are also alternating positive and negative. The alternating positive and negative charges can avoid the problem of charge accumulation on the insulating substrate after long-term printing. The grounding of the worktable 28 makes the potential of the substrate 29 of the curved surface to be printed zero. The positive voltage applied to the nozzle 36 is higher than the voltage applied to the annular electrode 31, so that a gradient potential difference is formed between the nozzle 36, the annular electrode 31 and the substrate 29 of the curved surface to be printed. The voltage between the annular electrode 31 and the worktable 28 is reduced by multi-level voltage control, thereby reducing the impact of the polarization of the insulating substrate on printing.

[0082] The airflow assist system includes a gas buffer chamber 35, a vent pipe, a conical chamber 32, and an air pipe 37. The gas buffer chamber 35 is located above the conical chamber 32. The gas buffer chamber 35 is arranged in a ring around the nozzle 36. Several vent pipes are located below the gas buffer chamber 35. The inlet and outlet ends of the vent pipes are connected to the outlet of the gas buffer chamber 35 and the conical chamber 32, respectively. The air pipe 37 is located below the conical chamber 32 and is coaxially arranged around the nozzle 36, forming an airflow channel between the air pipe 37 and the nozzle 36. An auxiliary airflow is introduced between the nozzle 36 and the annular electrode 31. The airflow auxiliary system is coaxially integrated around the nozzle 36. The gas enters from the air inlet 33 on the side of the gas buffer chamber 35. The air inlet 33 of the gas buffer chamber 35 is connected to a pressurized air source. The gas from the air source is homogenized by the annular gas buffer chamber 35 and then flows into the conical chamber 32 and converges into the air pipe 37. The airflow flows in from the cylindrical area between the nozzle 36 and the air pipe 37 and finally focuses onto the electro-hydraulic jet 30. The jet 30 is ejected from the outlet of the airflow auxiliary system, and the ink is precisely sprayed onto the curved substrate 29 to be printed.

[0083] like Figure 2 As shown, the nozzle 36 in the printhead module 8 has a slender tube structure. The diameter of the nozzle 36 is allowed to be slightly larger than that of the nozzle 36 in general electrohydraulic inkjet equipment, which can reduce the processing difficulty of the nozzle 36 and improve the manufacturing efficiency. The nozzle 36 maintains a fixed distance from the bottom of the airflow-assisted system. The distance between the annular electrode 31 and the nozzle 36 can be adjusted by installing annular electrodes 31 of different thicknesses according to the jetting process requirements. Because high-precision airflow-assisted electrohydraulic conformal printing equipment needs to complete the printing and jetting of various complex curved surfaces, especially the printing of many concave surfaces, the printhead module 8 cannot be too large. Otherwise, interference between the printhead module 8 and the workpiece surface will occur, making it impossible to accurately approach the printed surface for printing. The printhead module 8 is relatively small in size. Depending on the actual needs, a single-tube printhead or multiple printheads can be selected, provided that the size of the nozzle group 36 meets the narrowest shape requirements of the printed entity surface, i.e., the substrate 29. When the surface shape allows, multiple material nozzles 36 can jet ink simultaneously to improve the printing speed.

[0084] The ink tank 34 is used to store the ink to be printed. The ink in the ink tank 34 is stably supplied to the nozzle 36 by the infusion tube 24 under the drive of the flow pump 23. The high voltage power supply 26 applies a high alternating voltage to the conductive ink and applies a low voltage to the auxiliary ring electrode 31. The potential on the printed object, i.e. the substrate 29, is zero. Multi-level voltage control, supplemented by airflow, forms a stable curved electric field between the nozzle 36 and the non-planar substrate that does not change with the posture of the substrate 29, providing a stable force field for the conductive ink at the nozzle 36.

[0085] In this embodiment, the gas-fluid-assisted method is used as a complementary method to overcome the inherent limitations of electrohydraulic printing, and it is a dual manufacturing process that combines the two methods.

[0086] When the printing material is a conductive ink that is sensitive to an electric field, gas-fluid is applied to the electrofluid jet as an auxiliary process; when the printing material is a material that is not sensitive to an electric field, gas-fluid focusing jetting is used as the main process to focus and jet the droplets, depositing the electrically insensitive ink at a higher production rate.

[0087] When using the airflow-assisted electrohydraulic inkjet printing method, compressed air is allowed to enter the conical chamber 32, the printhead module 8 is supplied with a high positive voltage, the annular electrode 31 is supplied with a low positive voltage, the collection stage 28 is grounded, and a strong electric field is formed between the nozzle 36 and the stage 28. The liquid is drawn out of the nozzle 36 by electricity under the assistance of the airflow field. When only the airflow focusing jet method can be used, the switch is turned off to remove the electric field between the nozzle 36 and the substrate 29. The collection substrate 29 does not need to be grounded. At the same time, the collection substrate can be any curved substrate 29 made of insulating material or a non-curved substrate 29. Pressurized gas enters the conical chamber 32, forcing the ink cavity to form a pointed cone similar to a Taylor cone 38. Then, accompanied by the flowing air, the liquid jet is ejected from the orifice.

[0088] In this embodiment, gas flows into the gas buffer chamber 35 through the air inlet 33 for buffering. The buffered gas then flows into the conical chamber 32 through multiple air vents, and then into the air pipe 37 through the conical chamber 32, focusing onto the tip of the nozzle 36 to act on the solution printed by the nozzle 36, thereby improving the printing accuracy of the solution. The transition surfaces of the conical airflow channel are all smooth arc transition surfaces, which can ensure smooth airflow, avoid the generation of airflow eddies, reduce airflow interference, and help improve the airflow constraint effect and enhance the stability of the printing solution jet. In airflow-assisted electrohydraulic inkjet printing, the airflow is air, and its relevant physical properties are constant when using a given solution. Therefore, in the airflow-assisted electrohydraulic inkjet printing of this embodiment, the flow rate of the auxiliary airflow is a quantity that needs to be controlled to ensure that the flow rate of the airflow is similar to that of the jet, so as to reduce the viscous shear force on the jet and improve the stability of the jet.

[0089] The airflow assist system is connected to the nozzle 36 by a cylindrical connector. Multiple vent pipes are arranged around the connector, and the upper and lower ends of the vent pipes are respectively connected to a gas buffer chamber 35 and a conical chamber 32 for buffering the airflow. The nozzle 36 is connected to the conical chamber 32 and the air pipe 37 by threads.

[0090] The printhead module 8 includes a printhead holder connected to an air inlet 33, a connector with an air vent, and an ink tank 34 for support. The printhead holder has a threaded hole for connecting to the ink tank 34. In this embodiment, the central axis of the threaded hole coincides with the central axis of the printhead holder.

[0091] In this embodiment, the central axis of several vent pipes is set at a predetermined distance from the central axis of the threaded hole. The two ends of the conductive wire are respectively connected to a high-voltage power supply 26 and a nozzle 36, which are housed within the through hole.

[0092] visual system

[0093] The vision system is mainly used for reference alignment and real-time visual monitoring of the substrate 29 to be printed during the printhead ejection process. Specifically, the positioning camera 9 is used for real-time precise positioning between the substrate 29 and the nozzle 36. At the start of printing, a special mark (usually a crosshair, but other shapes can also be used) is printed at a specific location. Simultaneously, an independent high-resolution camera captures images of the mark and, based on image recognition technology, decomposes the deviations in the five degrees of freedom (X, Y, Z, B, C). The deviations are then controlled to correct the deviations along the five motion axes. After correction, the printed surface circuit is directly printed. During printing, the observation camera 2 is used to monitor the Taylor cone 38 of the electro-jet jet 30 and the gas-fluid focusing jet 30 in real time. By monitoring the jet morphology throughout the process, the liquid state at the tail of the nozzle 36 can be observed in real time, allowing for timely adjustment of printing process parameters to print the required high-quality, high-precision curved surface circuit.

[0094] CNC system

[0095] The CNC system of a high-precision airflow-assisted electrohydraulic conformal printer is the core of the entire equipment. With the aforementioned five-axis motion system and printhead system, the CNC system needs to tightly integrate the control of the five-axis motion system and the printhead system. Simultaneously, it must fully utilize software advantages to achieve the function of planning the motion trajectory from three-dimensional curved surface modeling to solid motion, in order to realize complete three-dimensional printing functionality. Therefore, the supporting CNC system must not only meet the requirements of various real-time motion control and synchronous printing control, but also have powerful motion trajectory planning capabilities. A control system that can simultaneously meet these functions needs not only strong real-time control capabilities, but also synchronous control capabilities, and must also possess strong capabilities in three-dimensional modeling processing, computer-aided design, and computer-aided manufacturing (CAD / CAM) processing.

[0096] The high-precision airflow-assisted electro-hydraulic conformal printing equipment of this embodiment adopts a control system with a multi-general-purpose PC parallel processing structure. Multiple PCs are used to complete different tasks. The core structure consists of two PCs working with general-purpose I / O boards. The PCs interact with each other in real time through a real-time data link to complete the parallel control tasks. The first PC runs on a general-purpose multi-tasking operating system software platform and mainly completes functions such as 3D processing, motion trajectory planning, computer-aided design and auxiliary processing, human-computer interaction and network communication. The second PC runs on a general-purpose strong real-time operating system software platform. On this PC, different real-time motion control, printing control and other auxiliary control functions are realized by configuring various computer general-purpose bus multi-function boards, motion control boards, bus communication boards and other controllers. It mainly realizes real-time motion control and real-time inkjet control, as well as the synchronous control between the two, and online information processing.

[0097] Specifically, the CNC system includes a three-axis motion control section, a two-axis rotation control section, and an electrical signal control section. The electrical signal control section includes current fluid injection control and auxiliary airflow injection control, all highly integrated in the form of control cards and software. It is used both to control the coordinated movement of motion modules to achieve the required printing circuitry on complex curved surfaces, and to provide electrical signals and flow rates to the conformal printing mold via the high-voltage power supply 26 and the flow pump 23. By controlling the provided electrical signals and flow rates, combined with the precise control of the motion modules, real-time on-demand control of the printing process on arbitrary curved surfaces can be achieved.

[0098] This embodiment provides a high-precision airflow-assisted conformal electro-hydraulic printing device. The airflow-assisted electro-inking system, through a five-axis motion system, achieves conformal printing of electro-hydraulic fluid on curved surfaces, overcoming the limitation of non-planar substrate shapes on the uniformity of the applied electric field and solving the interference problem caused by the curved surface electric field on the electro-hydraulic printing jet. By incorporating an annular electrode 31 within the airflow-assisted electro-inking printhead, the voltage between the annular electrode 31 and the insulating substrate is significantly reduced, solving the problem of the influence of insulating substrate polarization on electro-hydraulic printing. The distance between the annular electrode 31 and the nozzle 36 can be adjusted by installing annular electrodes 31 of different thicknesses, making operation convenient. By applying auxiliary airflow between the printing nozzle 36 and the annular electrode 31, the airflow changes the movement direction of the jet 30 ejected from the nozzle 36, which can both guide the jet 30 for precise positioning and constrain the airflow, overcoming the limitation of the distance between the printhead and the substrate. The limitations of traditional printing methods have been overcome, improving the accuracy of electrohydraulic printing. Air focusing allows for the printing of materials less sensitive to electric fields, overcoming the limitations imposed by the conductivity of the printing materials themselves and broadening their application range. Gas focusing assists electrohydraulic printing, enabling the jetting of fluids with higher Reynolds numbers, eliminating the strong dependence of droplet or jet size on flow velocity and improving jetting efficiency. The airflow channel formed by the gas buffer chamber 35, the conical chamber 32, and the air pipe 37 achieves buffering and focusing of the airflow, improving print quality. The nozzle 36, treated with a hydrophobic coating, prevents liquid from wetting its edges and ensures a repeatable conical base for repeatable conical jet transitions. The auxiliary airflow focuses the liquid flowing from the nozzle 36, causing the liquid to form a cone at the nozzle tip (i.e., the orifice), similar in shape to the Taylor cone produced in electrohydraulic printing. In addition, the observation camera 2 and the positioning camera 9 in the vision system are used to observe the Taylor cone 38 of the electrohydrodynamic printing jet in real time by aligning the observation camera 2 with the nozzle 36, and to achieve real-time accurate positioning between the substrate 29 and the nozzle 36 by aligning the positioning camera 9 with the curved surface, thereby improving the printing quality.

[0099] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A high-precision airflow-assisted electrohydraulic conformal printing device, characterized in that, The system includes a nozzle system comprising a nozzle module (8), an airflow assist system, and an electrical signal supply section; the airflow assist system is symmetrically arranged around the central axis of the nozzle module (8); the nozzle module (8) is connected to the electrical signal supply section. The nozzle module (8) includes a nozzle (36); the airflow assist system includes a gas buffer chamber (35), an air duct, a conical chamber (32), and an air pipe (37); The gas buffer chamber (35) is located above the conical chamber (32); the gas buffer chamber (35) is arranged in a ring around the nozzle (36); several vent pipes are located below the gas buffer chamber (35); the inlet end and outlet end of the vent pipes are connected to the outlet of the gas buffer chamber (35) and the conical chamber (32) respectively; the air pipe (37) is located below the conical chamber (32); the air pipe (37) is coaxially arranged around the nozzle (36); and an airflow channel is formed between the air pipe (37) and the nozzle (36). The nozzle module (8) also includes an annular electrode (31); the annular electrode (31) is coaxially disposed below the nozzle (36) and the air pipe (37); The electrical signal supply section includes a high-voltage power supply (26) and a high-voltage amplifier (25). The high-voltage power supply (26) and high-voltage amplifier (25) are used to apply voltage to the inner wall of the nozzle (36) and the annular electrode (31). The nozzle (36) is connected to the positive high voltage, the annular electrode (31) is connected to the positive low voltage, and the negative high voltage is connected to the worktable (28). The bottom end of the nozzle (36) is located above the bottom end of the air pipe (37) and maintains a fixed distance; An air inlet (33) is provided on the side of the gas buffer chamber (35); The inner wall of the outlet of the trachea (37) contracts toward the center; The airflow flowing out of the air tube (37) forms an airflow sleeve, which surrounds the ink droplet; The electrical signal supply section also includes a flow supply module and a pressure balance system connected to each other. The flow supply module is used to adjust the flow rate of ink ejected from the nozzle (36). The high-voltage power supply (26) is used to generate positive and negative alternating voltage, and the voltage signal is amplified by 1000 times by the high-voltage amplifier (25) and applied between the nozzle (36) and the substrate (29); The bottom end of the conical chamber (32) has an air outlet coaxial with the nozzle (36).

2. The high-precision airflow-assisted electrohydraulic conformal printing equipment according to claim 1, characterized in that, The air inlet (33) is connected to a pressurized air source.

3. The high-precision airflow-assisted electrohydraulic conformal printing equipment according to claim 1, characterized in that, It also includes a vision system, which includes a positioning camera (9) and an observation camera (2). The positioning camera (9) is set perpendicular to the substrate (29), and the observation camera (2) is set aligned with the nozzle (36). The observation camera (2) is used to observe the Taylor cone (38) of the jet (30) being printed in real time during the printing process. The positioning camera (9) is used for real-time precise positioning between the curved substrate (29) and the nozzle (36).

4. The high-precision airflow-assisted electrohydraulic conformal printing equipment according to claim 1, characterized in that, It also includes a five-axis motion system, which includes a support column (20), a Z-axis motion group (22) is provided inside the support column (20), a support plate (3) is provided between the two Z-axis motion groups (22), a connecting base plate (10) is provided on the support plate (3), and a nozzle module (8) is provided on the connecting base plate (10). A worktable (28) is provided directly below the nozzle module (8), a two-dimensional rotary table (18) is provided below the worktable (28), a Y-axis group (14) is provided below the two-dimensional rotary table (18), an X-axis group (6) is provided below the Y-axis group (14), and a movable slide (5) is provided between the Y-axis group (14) and the X-axis group (6).

5. The high-precision airflow-assisted electrohydraulic conformal printing equipment according to claim 4, characterized in that, The two-dimensional rotary table (18) includes a first rotating part (15) and a second rotating part (12); The second rotating part (12) is mounted on the platform of the first rotating part (15); The first rotating part (15) rotates around the Y-axis, and the second rotating part (12) rotates around the normal direction of the plane perpendicular to the first rotating part (15).

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