Array nozzle of integrated heating layer

Abstract

The invention belongs to the related technical field of ink-jet printing, and particularly relates to a heating layer integrated array nozzle which comprises an ink box, a protective layer, a heating layer, a micro-channel layer and an array nozzle which are sequentially connected from top to bottom. A groove is formed in the upper surface of the heating layer, a plurality of heat units are sequentially stacked in the groove from bottom to bottom, each unit comprises an electric insulation layer, an adhesion layer and a heating wire which are sequentially stacked to form a heat island area, and the area of the heat island area can cover a flow channel area in the micro-flow channel layer; the heating device is used for uniformly heating the ink in the whole ink conveying path in the micro-channel layer, so that the ink in the narrow branched channel is maintained at the required injection temperature; the protective layer completely covers the groove, and an air gap is formed between the protective layer and the heating wire; a micro-channel outlet is formed in the upper surface of the micro-channel layer and used for discharging ink of an outlet convergence channel of the branch channels to an external ink path. According to the invention, the viscosity application range of the ink jettable by the array nozzle can be improved, and the ink coagulation and blockage risk can be reduced.

Description

Technical Field

[0001] This invention belongs to the technical field of inkjet printing, and more specifically, relates to an arrayed printhead with an integrated heating layer. Background Technology

[0002] Electrohydraulic inkjet printing is an advanced additive manufacturing process that uses a high-voltage electric field to induce ink at the nozzle to form a Taylor cone and spray it onto the substrate, achieving the deposition of patterned functional structures. Unlike traditional piezoelectric or thermal inkjet printing technologies, which "push" ink droplets out of the nozzle, electrohydraulic inkjet printing uses a "pulling" method in principle. It employs an electric field to pull the ink out of the nozzle, giving it advantages such as high resolution, a wide range of ink viscosity adaptability, and high-precision patterning. This technology has shown broad application prospects in fields such as functional material printing, microelectronic packaging, and biomanufacturing.

[0003] However, electrohydraulic inkjet printing technology is suitable for a wide range of ink viscosities, from 1 to 10,000 cP. This results in significantly increased flow resistance for high-viscosity inks within the printhead, especially in narrow channels. During prolonged continuous or intermittent operation, ink may stagnate in localized areas, leading to printhead clogging, drastically shortening printhead lifespan, and reducing print quality. Therefore, effectively suppressing stagnation and clogging of high-viscosity inks within the flow channels is crucial for the design and performance optimization of the microchannel structure within arrayed printheads.

[0004] Chinese patent CN204586129U proposes an adjustable pressure printhead ink cavity internal circulation structure. By controlling the ink supply pressure, it achieves full-flow internal circulation of ink within the ink cavity, thereby significantly improving the printhead's continuous operating time and reducing maintenance costs. However, this solution still carries the risk of introducing impurities into the ink path, thus reducing print quality. On the other hand, Chinese patent CN116728776A proposes a printhead internal temperature control scheme, which heats the ink by introducing a ring heating coil at the printhead inlet tube, aiming to solve the printhead clogging problem. However, this scheme is only applicable to extrusion piezoelectric printheads and not to other complex structures such as electrohydrodynamic printheads, bending piezoelectric printheads, and shearing piezoelectric printheads. Therefore, this heating scheme has limitations. Summary of the Invention

[0005] In view of the above-mentioned defects or improvement needs of the prior art, the present invention provides an arrayed printhead with an integrated heating layer, which aims to improve the viscosity range of the ink that the arrayed printhead can spray and reduce the risk of ink stagnation and clogging, thereby improving spraying stability and process reliability.

[0006] To achieve the above objectives, according to one aspect of the present invention, an arrayed printhead with an integrated heating layer is provided, comprising an ink cartridge (1), a protective layer (2), a heating layer (3), a microchannel layer (4), and an array nozzle (6) connected sequentially from top to bottom. The upper surface of the heating layer (3) is provided with a groove, and m thermal units are stacked in the groove from bottom to top, where m is greater than or equal to 1. Each thermal unit includes an electrical insulation layer (12), an adhesive layer (11) for fixing the heating wire, and a heating wire (15) stacked in the groove from bottom to top, forming a heat island area (10). The area of ​​the heat island area can cover the multi-level branched flow channel area in the microchannel layer (4), which is used to uniformly heat the ink in the entire ink delivery path in the microchannel layer (4) so ​​that the ink in the narrow branched flow channel is maintained at the required spraying temperature. The protective layer (2) completely covers the groove and has an air gap (9) between it and the heating wire (15) for electrically isolating the heating wire. The upper surface of the microchannel layer (4) is provided with multi-level branched channels, microchannel inlet (7) and microchannel outlet (8). The microchannel inlet (7) is used to connect the total inlet channel of the multi-level branched channels with the ink chamber in the ink cartridge (1) to introduce the ink in the ink chamber into the total inlet channel. The microchannel outlet (8) is used to discharge the ink from the outlet convergence channel of the multi-level branched channels to the external ink path. The array through holes corresponding to the array nozzle (6) are located at the center of each branched channel of the last level of the microchannel layer (4) and extend to the lower surface of the microchannel layer (4).

[0007] Furthermore, the heating wire (15) has a uniformly coiled serpentine pattern structure.

[0008] Furthermore, the area covered by the heating wire (15) is a rectangular area, and the layout of the heating wire (15) is a uniformly coiled square shape. The structural dimensions of the heating wire (15) are determined by the following method: The heat island region (10) is considered as a rectangular area with a length of... Width is Leave a gap around the area f The length of the rectangular area covered by the heating wire (15) is... ,width The wire width of the heating wire (15) is b The center distance between any two adjacent heating wire segments along the length of the rectangular area covered by the heating wire (15) is... , The spacing between the conductor segments, and the number of bendable conductor segments in the heating conductor along its length. The total length of the heating wire (15) The expression is:

[0009] By preset , , f , b , The value of is calculated. , , , The structural dimensions of the heating wire (15) are determined.

[0010] Furthermore, the heating wires (15) are arranged symmetrically in two separate regions of the serpentine pattern structure.

[0011] Furthermore, a temperature sensor is provided in the outer area of ​​the heating wire (15) in the groove, arranged in a ring, for real-time monitoring of the ink temperature in the multi-level branched channels in the microchannel layer (4).

[0012] Furthermore, the temperature of the ink within the multi-stage bifurcated flow channels for:

[0013] In the formula, This indicates the stable temperature of the heat island area (10) after being heated by the heating wire (15). This indicates the input current of the heating wire (15). This indicates the total resistance of the heating wire (15). , This indicates the resistivity of the material of the heating wire (15). To determine the cross-sectional area of ​​the heating wire (15), Indicates the total length of the heating wire (15); The value is 3m, which represents the number of thin film layers in the heat island area (10). , and The first i The thickness, thermal conductivity, and cross-sectional area of ​​the layer; Indicates the heat transfer coefficient on the flow channel side. This indicates the heat exchange area of ​​the ink.

[0014] Furthermore, the connection shape between adjacent bifurcation channels in the microchannel layer (4) is a ring-shaped bifurcation, a rectangular bifurcation, or a triangular bifurcation; based on the range =( — ) / To measure flow uniformity, simulations were used to determine the bifurcation shape that resulted in low flow resistance and uniform ink supply. , These represent the maximum and minimum flow rates of each nozzle. This represents the average flow rate of each nozzle. In the simulation, each branched flow channel satisfies the continuity equation: ,in, For the first The average flow velocity within the bifurcation channel, For the first The cross-sectional areas of all branched flow channels in a multi-stage flow system are summed; the cross-sectional shapes of the first-stage, second-stage, and third-stage flow channels in a multi-stage flow system are rectangular or trapezoidal.

[0015] Furthermore, the heating wire (15) is a platinum thin film.

[0016] According to another aspect of the present invention, an arrayed printhead printing system is provided, including a power supply, a host computer, a heating unit, a driving unit, and an arrayed printhead, wherein the printhead is an arrayed printhead as described in any one of claims 1 to 8; the heating unit includes a heating wire (15) located in the heat island area, a heating electrode (16) located outside the arrayed printhead, and a control interface thereof; both ends of the heating wire (15) are led out through conductive extension areas and connected to the heating electrode (16), and the heating electrode (16) is connected to the control interface; The drive unit includes a control electrode (13), an array nozzle (6), and a boss electrode (14) surrounding each nozzle; each boss electrode (14) is controlled by the control electrode (13), and the opening and closing of the array nozzle (6) is controlled by the voltage of the control electrode (16). The decision is made that when a designated nozzle is operating, the host computer outputs a command and controls the voltage. In addition, the host computer dynamically adjusts the heating voltage through the control interface based on the temperature feedback and working status of the electro-hydraulic nozzle. When the nozzle is in spray mode, a PID closed-loop algorithm is used to control the voltage. Maintain the ink temperature within the preset window; reduce the heating voltage when the printhead is in standby or during intermittent operation. Avoid localized overheating; heating voltage With driving voltage All of these are controlled by the coding program on the host computer.

[0017] In summary, compared with the prior art, the technical solutions conceived by this invention have the following main advantages: This invention proposes an arrayed printhead with an integrated heating layer. A heat island region is set between the ink cartridge and the microchannel layer. This region completely covers the multi-level branching channels in the microchannel layer, uniformly heating the ink throughout the entire delivery path and maintaining the high-viscosity ink in the narrow etched channels at a suitable ejection temperature. The heating function of the heat island region is achieved by a multi-layer heating film. Each heat unit film layer structure includes, from bottom to top, an insulating layer, an adhesive layer, and a heating wire. The two ends of the heating wire are connected to heating electrodes. This solution achieves a stable and uniform thermal field distribution through the multi-layer heating film structure, ensuring that the high-viscosity ink maintains a suitable ejection temperature in the narrow channels, effectively preventing ink clogging, thereby improving the stability of the ejection process and making it applicable to various complex printhead structures. Furthermore, this invention proposes a pollution-free ink cartridge structure. The cartridge contains an independent ink storage cavity and employs a unidirectional circulating ink supply method. This means the ink storage cavity is not directly connected to the ink outlet channel. Ink is transported through the ink storage cavity to the microchannel inlet, evenly distributed to each nozzle path in the branched flow channels, and then discharged from the ink outlet, avoiding repeated heating or deposition of the ink. Therefore, this invention can improve the viscosity range of inks that can be jetted by arrayed printheads and reduce the risk of ink stagnation and clogging, thereby improving jetting stability and process reliability. Attached Figure Description

[0018] Figure 1 An exploded view of the structure of an arrayed nozzle with an integrated heating layer provided in an embodiment of the present invention; Figure 2 An exploded view of an arrayed nozzle with an integrated heating layer provided in an embodiment of the present invention. Figure 3 A cross-sectional view of an arrayed nozzle with an integrated heating layer provided in an embodiment of the present invention; Figure 4 A top view of the heat island area of ​​the integrated single serpentine heating film layer provided in an embodiment of the present invention; Figure 5 This is a top view of the integrated dual-serpentine heating and temperature-sensing film layer heat island area provided in an embodiment of the present invention; Figure 6 This is a top view of the microchannel layer inside the nozzle chip provided in an embodiment of the present invention; Figure 7 A schematic diagram of optional shapes for connecting the branches of the bifurcated flow channel provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of the nozzle arrangement in an arrayed nozzle provided in an embodiment of the present invention; Figure 9 This is a cross-sectional view of the ink cartridge inlet / outlet provided in an embodiment of the present invention; Figure 10 This is a cross-sectional view of the ink cartridge fixing countersunk hole provided in an embodiment of the present invention; Figure 11This is a schematic diagram of a printing system with arrayed printheads provided in an embodiment of the present invention.

[0019] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1 is the ink cartridge; 2 is the protective layer; 3 is the heating layer; 4 is the microchannel layer; 5 is the protective layer; 6 is the array nozzle; 7 is the microchannel inlet; 8 is the microchannel outlet; 9 is the air gap; 10 is the heat island area; 11 is the adhesive layer; 12 is the insulating layer; 13 is the control electrode; 14 is the boss electrode; 15 is the heating wire; 16 is the heating electrode; 17 is the branched flow channel; 18 is the through hole; 19 is the ink inlet; 20 is the ink outlet; 21 is the ink storage cavity; 22 is the fixing countersunk hole; 23 is the fixing side plate; 24 is the substrate; 25 is the temperature sensing wire. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0021] Example 1 An arrayed printhead with an integrated heating layer includes an ink cartridge, a protective layer, a heating layer, a microchannel layer, and an array of nozzles connected sequentially from top to bottom. The upper surface of the heating layer has a groove, and m heating units are stacked sequentially from bottom to top in the groove, where m is greater than or equal to 1. Each heating unit includes an electrical insulation layer, an adhesive layer for fixing the heating wire, and a heating wire stacked sequentially from bottom to top, forming a heat island area. The area of ​​the heat island area is large enough to cover the multi-level branched flow channel area in the microchannel layer, which is used to uniformly heat the ink in the entire ink delivery path in the microchannel layer, so that the ink in the narrow branched flow channel is maintained at the required spraying temperature. The protective layer completely covers the groove and has an air gap between it and the heating wire for electrical isolation of the heating wire. The upper surface of the microchannel layer is provided with multi-stage branched channels, microchannel inlets and microchannel outlets. The microchannel inlet is used to connect the main inlet channel of the multi-stage branched channels with the ink chamber in the ink cartridge to guide the ink in the ink chamber into the main inlet channel. The microchannel outlet is used to discharge the ink from the outlet convergence channel of the multi-stage branched channels to the external ink path. The array through holes corresponding to the array nozzles are located at the center of each branched channel of the last stage of the microchannel layer and extend to the lower surface of the microchannel layer.

[0022] This embodiment incorporates a heat island region between the ink cartridge and the microchannel layer. This region completely covers the multi-level branching channels within the microchannel layer, uniformly heating the ink throughout the entire delivery path and maintaining the high-viscosity ink within the narrow etched channels at a suitable ejection temperature. The heating function of the heat island region is achieved through a multi-layer heating film. Each heat unit film layer structure, from bottom to top, includes an insulating layer, an adhesive layer, and a heating wire. The two ends of the heating wire are connected to heating electrodes. This solution achieves a stable and uniform thermal field distribution through the multi-layer heating film structure, ensuring that the high-viscosity ink maintains a suitable ejection temperature within the narrow channels, effectively preventing ink clogging, thereby improving the stability of the ejection process and making it suitable for various complex printhead structures.

[0023] In addition, this embodiment also proposes a pollution-free ink cartridge structure. The ink cartridge is equipped with an independent ink storage cavity and adopts a one-way circulating ink supply method. That is, the ink storage cavity is not directly connected to the ink outlet channel. The ink is transported to the microchannel inlet through the ink storage cavity in the ink cartridge, and is evenly distributed to each nozzle passage of the branched flow channel, and then discharged from the ink outlet, avoiding repeated heating of the ink or the formation of deposits.

[0024] In this embodiment, the microchannel outlet is used to discharge the ink from the convergence channel of the multi-stage branching channels to the external ink path. It can be led out through the ink cartridge outlet, which is not connected to the ink chamber. The ink storage cavity inside the ink cartridge is not directly connected to the ink outlet channel (ink cartridge outlet), ensuring that high-viscosity ink only enters the printhead through the ink inlet and exits through the ink outlet, while residual ink is discharged from the ink outlet channel. This avoids contamination of the ink in the ink storage cavity and maintains the purity of the ink supply system.

[0025] The protective layer is located between the ink cartridge and the heat island area, and there is an air gap between it and the heating wire to prevent the heating wire from directly contacting the outside world and to play an electrical isolation role; the protective layer may have ink inlet and outlet through holes, which are connected to the ink cartridge and the microchannel layer respectively.

[0026] The printhead may also include a hollow boss electrode, which is fitted around the array nozzle to facilitate electric field focusing and promote ink ejection; the array nozzle and the hollow boss electrode can be bonded to the lower surface of the nozzle plate with epoxy resin sealant, corresponding one-to-one with the through holes on the nozzle plate (i.e., the microchannel layer).

[0027] like Figures 1 to 4As shown, an exemplary arrayed electrohydrodynamic printhead with an integrated heating layer is provided, comprising an ink cartridge 1, a protective layer 2, a heating layer 3, a microchannel layer 4, and an array nozzle 6 connected in sequence; the upper surface of the microchannel layer 4 includes a branched flow channel 17, a microchannel inlet 7, and a microchannel outlet 8, and its lower surface is provided with a plurality of through holes 18; the array nozzle 6 is placed on a nozzle plate on the lower surface of the microchannel layer 4; the hollow boss electrode 14 is sleeved around the array nozzle 6, is made of conductive metal, and is electrically connected to a control electrode 13; wherein, the array nozzle 6 and the hollow boss electrode 14 are both firmly bonded to the lower surface of the microchannel layer 4 with epoxy resin sealant; wherein, the array nozzle 6, the through holes 18, and the boss electrode 14 are one-to-one corresponding and coaxially arranged, with a spacing of 550μm, and the diameter of the array nozzle 6 and the through holes 18 is 50μm, and the diameter of the boss electrode 14 is 100μm.

[0028] When the control electrode 13 is connected to a high-voltage power supply, a high-voltage electric field is formed between the array nozzle 6 and the substrate 26, inducing the ink in the nozzle to form a Taylor cone, thereby forming a jetting phenomenon. A hydrophobic protective layer 5 is provided below the nozzle plate to prevent the ink from wetting and spreading on the surface of the nozzle plate and the electrode area. It also has good corrosion resistance and insulation to avoid leakage and protect the electrode from oxidation. The ink in the ink cartridge 1 is transported to the microchannel inlet 7 through the ink storage cavity 21 and evenly distributed to each array nozzle 6 through the branched flow channel 17 to achieve a stable supply of high-viscosity ink. A heat island area 10 is provided between the ink cartridge 1 and the microchannel layer 4. A multilayer heating film 3 is integrated in the heat island area 10. The multilayer heating film 3 adopts a composite film structure. There is only one thermal unit in the figure, that is, m=1. Each thermal unit includes an insulating layer 12, an adhesive layer 11 and a heating wire 15 from bottom to top.

[0029] like Figure 3 As shown, this embodiment provides a structural design scheme for a heating layer 3. A protective layer 2 covers the upper part of the heating layer 3, and the lower part is closely attached to the microfluidic layer 4. An air gap 9 is formed between the upper protective layer 2 and the heating layer 3. On the one hand, the air gap 9 can effectively reduce heat loss to the outside, and on the other hand, the air gap 9 has a good electrical isolation effect. The protective layer 2 is made of an insulating material with a thickness of about 2mm. The two ends of the heating wire 15 are electrically connected to the heating electrode 16 respectively. When the power module applies voltage to the heating electrode 15, the heating wire 15 generates heat and transfers it downward to the microfluidic layer 4 through the heat conduction path, thereby realizing uniform heating of high viscosity ink in the narrow area within the microfluidic layer 4.

[0030] As a preferred embodiment, the heating wire has a uniformly coiled serpentine pattern structure.

[0031] like Figure 4As shown, this embodiment proposes several arrangements of the heating wires 15, including serpentine, double-serpentine, or grid-like arrangements; the coverage area of ​​the heat island 10 and the heating uniformity need to be comprehensively considered. Here, different arrangements are analyzed through finite element simulation, and the temperature difference is determined based on the simulation results. To select the arrangement shape of the heating wire 15.

[0032] As a preferred embodiment, the area covered by the heating wire is a rectangular area, and the heating wire is arranged in a uniformly coiled, zigzag pattern. Figure 4 As shown, the curved serpentine pattern structure consists of several parallel heating segments and connecting segments, with both ends of the serpentine wire connected to the heating electrode.

[0033] The structural dimensions of the heating wire are determined by the following method: Considering heat island zone 10 as a rectangular region with a length of... Width is Leave a gap around the area f The length of the rectangular area covered by the heating wire 15 is... ,width The wire width of heating wire 15 is b The center-to-center distance between any two adjacent heating wire segments along the length of the rectangular area covered by heating wire 15 is... , The spacing between the conductor segments, and the number of bendable conductor segments in the heating conductor along its length. The total length of the heating wire 15 The expression is:

[0034] By preset , , f , b , The value of is calculated. , , , The structural dimensions of the heating wire are determined.

[0035] This preferred approach proposes a size design scheme and layout relationship for a serpentine pattern heating wire; the heating wire is designed parametrically based on the area of ​​the heat island and the heating range, and the heating coverage area completely corresponds to the ink path in the bifurcation channel. This design scheme ensures the high efficiency of the heating function.

[0036] As a preferred embodiment, the heating wires are arranged symmetrically in two serpentine patterns, such as... Figure 5 As shown.

[0037] When supplying temperature-sensitive ink, the heating wires preferably adopt a double serpentine pattern structure, which can form a higher density of heating units within the same heating area, thereby achieving a faster thermal response speed; however, its wiring design and process preparation are relatively complex, and the manufacturing cost is higher than that of a single serpentine structure.

[0038] As a preferred embodiment, a temperature sensor (i.e., ...) is provided in the outer region of the heating wire inside the groove. Figure 5 The temperature-sensing wire 25 is arranged in a ring to monitor the ink temperature in the multi-level branched channels within the microchannel layer in real time.

[0039] A ring-shaped temperature sensor can be installed on the reserved area around the heating wire. The ring-shaped temperature sensor is arranged in a ring shape to completely cover the heating wire area and monitor the ink temperature in the microchannel in real time.

[0040] like Figure 5 As shown, this embodiment proposes an integrated dual serpentine heating and temperature-sensitive film structure. When supplying temperature-sensitive ink, the heating wire 15 preferably adopts a dual serpentine pattern structure, which can form a higher density of heating units within the same heating area, thereby achieving a faster thermal response speed. However, its wiring design and process preparation are relatively complex, and the manufacturing cost is higher than that of a single serpentine pattern structure.

[0041] For example, the preparation scheme of the heating film layer is as follows: a 1.5μm SiO2 insulating layer is prepared on a silicon substrate using a thermal oxidation process to effectively avoid electrical breakdown or short circuit. Due to the poor adhesion between the metal and SiO2, and to prevent interlayer peeling under thermal cycling conditions, an adhesive layer 11 must be added between the insulating layer 12 and the heating wire 15. The material of the adhesive layer 11 is preferably a chromium thin film, which is deposited on the insulating layer 12 using a magnetron sputtering process and has a thickness of 30nm. The heating wire 15 is preferably a platinum thin film with a width of 3μm and a thickness of 0.2μm. It is also deposited on the adhesive layer 11 using a magnetron sputtering process and combined with a photolithography patterning process to form a curved serpentine heating path. Lift-off peeling process is preferred. In addition, in order to improve the overall stability of the multilayer heating film 3, the film layer can be annealed at 300-400℃ after preparation to release the residual stress between the film layers and improve the interface stability.

[0042] As a preferred embodiment, the temperature of the ink within the multi-stage branched flow channels... for:

[0043] In the formula, This indicates the stable temperature of the heat island area after being heated by the heating wire. This indicates the input current to the heating wire. This indicates the total resistance of the heating wire. , This indicates the resistivity of the heating wire material. The cross-sectional area of ​​the heating wire. Indicates the total length of the heating wire; This indicates the number of thin film layers within the heat island zone, with a value of 3m. , and The first i The thickness, thermal conductivity, and cross-sectional area of ​​the layer; Indicates the heat transfer coefficient on the flow channel side. This indicates the heat exchange area of ​​the ink.

[0044] This can be used as a preferred implementation method, such as Figure 6 As shown, this embodiment provides a multi-stage branched flow channel structure for an arrayed nozzle, including a microchannel inlet 7, a microchannel outlet 8, branched flow channels 17, and an array of nozzles 6; the branched flow channels 17 are located on the front side of the microchannel layer 4 and are arranged in a tree-like shape.

[0045] The ink enters the ink storage cavity 21 inside the ink cartridge 1 through the ink inlet 19, and then enters the microchannel through the microchannel inlet 7. It forms a branch in the center through the main branch of the branch channel, and then is distributed step by step along the first, second and third branch channels, and finally delivered to the array nozzle 6 through the through hole 18. The through hole 18 corresponds to each array nozzle 6 and is arranged coaxially.

[0046] The flow channel cavity of the bifurcated flow channel 17 is constructed by laser ablation of a tree-like flow channel groove structure onto a ceramic sheet. For example, the depth is 100 μm, the width of the first-stage flow channel is 200 μm, and the widths of the second- and third-stage flow channels are determined according to the continuity equation. Calculations are performed; the cross-sectional shape of each flow channel can be rectangular or trapezoidal; by reasonably adjusting the width and length of the second and third flow channels, flow matching and pressure drop balance can be achieved.

[0047] This preferred approach proposes a design scheme suitable for multi-stage bifurcated channels within a microchannel layer, such as... Figure 7 As shown, the connection methods between each level can be: ring, rectangle or triangle, and a scheme to optimize the channel size of each level through simulation is proposed to ensure that the ink in the channel is evenly distributed to each array nozzle.

[0048] As shown in Figure 7, the arrangement shape of the tree-like flow channels can be annular, rectangular, or triangular. To achieve uniform ink supply to each nozzle branch under high-viscosity ink, this embodiment designs the tree-like flow channels using Murray's law, and then verifies the flow uniformity using finite element numerical simulation. The initial geometric configuration of each branch channel is designed based on Murray's law: ,in, The equivalent hydraulic radius of the main channel, This is the equivalent hydraulic radius of the corresponding sub-pipe.

[0049] This embodiment further introduces the finite element numerical simulation method to compare and analyze different flow channel structures. The flow field distribution, pressure drop, and flow rate of each branch are calculated numerically under high viscosity fluid conditions. Simultaneously, nozzle ink supply uniformity is achieved using a flow rate difference parameter. Conduct an assessment: In the formula, This indicates the maximum volumetric flow rate of each nozzle. This represents the minimum volumetric flow rate of each nozzle. This represents the average volumetric flow rate of each nozzle.

[0050] like Figure 8 As shown, the through hole 18 is located at the confluence center after the three-level bifurcation of the microchannel layer 4. The through hole 18 runs through the entire microchannel module, and its axis coincides with the symmetry axis of the corresponding boss electrode 14, ensuring that the ink is radially and uniformly transported from the central through hole to each array nozzle 6, forming an isobaric ink supply condition during the spraying stage.

[0051] like Figure 9 and Figure 10 As shown, an ink cartridge suitable for arrayed printheads is provided. The ink cartridge 1 includes an ink inlet 19, an ink outlet 20, an ink storage cavity 21, a microchannel inlet 7, a microchannel outlet 8, a fixed countersunk hole 22, and a fixed side plate 23. The fixed side plates 23 are located on both sides of the upper surface of the ink cartridge 1. Four fixed countersunk holes 22 are provided, all of which are set on the fixed side plates 23 on both sides of the ink cartridge 1. Each of them has threaded holes corresponding to the matching bolts inside, which are used to fix it to the work platform. The ink inlet 19 and ink outlet 20 of ink cartridge 1 are in the same plane (i.e., the upper surface of the ink cartridge) as the fixed countersunk hole 22; the microchannel inlet 7 and microchannel outlet 8 are arranged on the lower surface of the ink cartridge; the microchannel outlet 8 is directly connected to the ink outlet 20, and the ink storage cavity 21 is located between the microchannel inlet 7 and the ink inlet 19, so that the two are connected to each other. The flow controller controls the flow rate of the ink inlet 19. Specifically, ink enters the ink storage cavity 21 from the ink inlet 19 through the external ink supply tube. The ink storage cavity 21 has a buffering function. When ink is replenished in the ink cartridge 1, the ink gradually fills the ink storage cavity 21, and the air is driven to the nozzle or discharged from the ink outlet 20 of the ink cartridge 1. After the air in the ink cartridge 1 and each layer of the flow channel is exhausted, the electro-hydraulic printhead can be driven to spray.

[0052] In this example, the ink outlet 20 is connected to the microchannel outlet 8, but not directly connected to the ink storage cavity 21. The ink flowing out of the microchannel through the microchannel outlet 8 is discharged through the ink outlet 20. This design ensures that high-viscosity ink is discharged only from the ink outlet 20 inside the ink cartridge 1, forming a unidirectional circulating flow path. This avoids the ink in the microchannel from contaminating the ink in the ink cartridge due to the introduction of air and nozzle impurities when passing through the nozzle, thereby effectively reducing the contamination of the ink in the ink cartridge 1. In addition, the volume of the ink storage cavity 21 is designed according to the supply flow rate of the arrayed printhead. The ink cartridge 1 is made of insulating material, such as polyimide or epoxy resin, and is integrally formed by injection molding or 3D printing. The fixed side plate 23 in the upper part of the ink cartridge 1 is provided with a fixed countersunk hole 22, which fixes the ink cartridge 1 to the working platform by screwing. A hydrophobic protective layer 5 is coated on the lower surface of the nozzle plate in the microchannel layer 4. The hydrophobic material is Teflon, which is prepared by vapor deposition process to avoid the ink from wetting and spreading in the nozzle plate.

[0053] The overall assembly of this embodiment includes an ink cartridge 1, a protective layer 2, a heating layer 3, a microfluidic layer 4, and an array of nozzles 6. Interlayer bonding is achieved through the following methods: In specific implementation, the protective layer 2, heating layer 3, and microfluidic layer 4 can be bonded using a low-temperature bonding process to achieve a dense bond between the inner film layers of the printhead chip assembly; the printhead chip assembly and ink cartridge 1 can be bonded together using epoxy resin sealant; and the array of nozzles 6 can also be bonded to the printhead chip assembly using epoxy resin adhesive. During assembly, the overall sealing of each component must be ensured; the entire assembly can be securely connected to the working platform by bolts on the fixing countersunk hole 22.

[0054] Example 2 An arrayed printhead printing system, wherein the printhead used is an arrayed printhead as described above.

[0055] As a preferred embodiment, it includes a power supply, a host computer, a heating unit, a driving unit, and an arrayed nozzle; the heating unit includes a heating wire located in the heat island area, a heating electrode located outside the arrayed nozzle, and a control interface; both ends of the heating wire are led out through conductive extension areas and connected to the heating electrode, and the heating electrode is connected to the control interface; a narrow connection area is provided between the pad and the heating wire to reduce thermal stress concentration; The drive unit includes a control electrode 13, an array nozzle 6, and a boss electrode 14 surrounding each nozzle; each boss electrode 14 is controlled by the control electrode 13, and the opening and closing of the array nozzle 6 is controlled by the voltage of the control electrode 16. The decision is made that when a designated nozzle is operating, the host computer outputs a command and controls the voltage. In addition, the host computer dynamically adjusts the heating voltage through the control interface based on the temperature feedback and working status of the electro-hydraulic nozzle. When the nozzle is in spray mode, a PID closed-loop algorithm is used to control the voltage. Maintain the ink temperature within the preset window; reduce the heating voltage when the printhead is in standby or during intermittent operation. Avoid localized overheating; heating voltage With driving voltage All are controlled by the coding program of the host computer. The maximum operating voltage of the heating wire 15 does not exceed 50V.

[0056] The boss electrode is made of conductive material and is electrically connected to the control electrode. When the control electrode is connected to a high-voltage power supply, a high-voltage electric field is formed between the array nozzle and the substrate. The ink is stretched and forms a Taylor cone under the action of the electric field force, which further generates the jetting phenomenon. The boss electrode, the array nozzle, and the through holes on the microchannel layer are all coaxially arranged and correspond to the center position of the heat island area to ensure that the ink is radially and uniformly delivered to each array nozzle through the central through hole.

[0057] The relevant technical solutions are the same as in Embodiment 1, and will not be repeated here.

[0058] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An arrayed nozzle with an integrated heating layer, characterized in that, It includes an ink cartridge (1), a protective layer (2), a heating layer (3), a microchannel layer (4), and an array nozzle (6) connected sequentially from top to bottom; The upper surface of the heating layer (3) is provided with a groove, and m thermal units are stacked in the groove from bottom to top, where m is greater than or equal to 1. Each thermal unit includes an electrical insulation layer (12), an adhesive layer (11) for fixing the heating wire, and a heating wire (15) stacked in the groove from bottom to top, forming a heat island area (10). The area of ​​the heat island area can cover the multi-level branched flow channel area in the microchannel layer (4), which is used to uniformly heat the ink in the entire ink delivery path in the microchannel layer (4) so ​​that the ink in the narrow branched flow channel is maintained at the required spraying temperature. The protective layer (2) completely covers the groove and has an air gap (9) between it and the heating wire (15) for electrically isolating the heating wire. The upper surface of the microchannel layer (4) is provided with multi-level branched channels, microchannel inlet (7) and microchannel outlet (8). The microchannel inlet (7) is used to connect the total inlet channel of the multi-level branched channels with the ink chamber in the ink cartridge (1) to introduce the ink in the ink chamber into the total inlet channel. The microchannel outlet (8) is used to discharge the ink from the outlet convergence channel of the multi-level branched channels to the external ink path. The array through holes corresponding to the array nozzle (6) are located at the center of each branched channel of the last level of the microchannel layer (4) and extend to the lower surface of the microchannel layer (4).

2. The arrayed nozzle as described in claim 1, characterized in that, The heating wire (15) has a uniformly coiled serpentine pattern structure.

3. The arrayed nozzle as described in claim 2, characterized in that, The area covered by the heating wire (15) is a rectangular area, and the layout of the heating wire (15) is a uniformly coiled square shape. The structural dimensions of the heating wire (15) are determined by the following method: The heat island region (10) is considered as a rectangular area with a length of... Width is Leave a gap around the area f The length of the rectangular area covered by the heating wire (15) is... ,width The wire width of the heating wire (15) is b The center distance between any two adjacent heating wire segments along the length of the rectangular area covered by the heating wire (15) is... , The spacing between the conductor segments, and the number of bendable conductor segments in the heating conductor along its length. The total length of the heating wire (15) The expression is: By preset , , f , b , The value of is calculated. , , , The structural dimensions of the heating wire (15) are determined.

4. The arrayed nozzle as described in claim 2, characterized in that, The heating wire (15) is arranged symmetrically in two separate areas of the serpentine pattern structure.

5. The arrayed nozzle as described in any one of claims 1 to 4, characterized in that, A temperature sensor is provided in the outer area of ​​the heating wire (15) in the groove, arranged in a ring, for real-time monitoring of the ink temperature in the multi-level branched flow channels in the microchannel layer (4).

6. The arrayed nozzle as described in claim 1, characterized in that, Temperature of ink in multi-stage bifurcation channels for: In the formula, This indicates the stable temperature of the heat island area (10) after being heated by the heating wire (15). This indicates the input current of the heating wire (15). This indicates the total resistance of the heating wire (15). , This indicates the resistivity of the material of the heating wire (15). To determine the cross-sectional area of ​​the heating wire (15), Indicates the total length of the heating wire (15); The value is 3m, which represents the number of thin film layers in the heat island area (10). , and The first i The thickness, thermal conductivity, and cross-sectional area of ​​the layer; Indicates the heat transfer coefficient on the flow channel side. This indicates the heat exchange area of ​​the ink.

7. The arrayed nozzle as described in claim 1, characterized in that, The connection shape between adjacent bifurcation channels in the microchannel layer (4) can be annular, rectangular, or triangular; based on the range =( — ) / To measure flow uniformity, simulations were used to determine the bifurcation shape that resulted in low flow resistance and uniform ink supply. , These represent the maximum and minimum flow rates of each nozzle. This represents the average flow rate of each nozzle. In the simulation, each branched flow channel satisfies the continuity equation: ,in, For the first The average flow velocity within the bifurcation channel, For the first The cross-sectional areas of all branched flow channels in a multi-stage flow system are summed; the cross-sectional shapes of the first-stage, second-stage, and third-stage flow channels in a multi-stage flow system are rectangular or trapezoidal.

8. The arrayed nozzle as described in claim 1, characterized in that, The heating wire (15) is a platinum thin film.

9. An arrayed printhead printing system, characterized in that, The device includes a power supply, a host computer, a heating unit, a drive unit, and an arrayed nozzle, wherein the nozzle is an arrayed nozzle as described in any one of claims 1 to 8; the heating unit includes a heating wire (15) located in the heat island area, a heating electrode (16) located outside the arrayed nozzle, and a control interface thereof; both ends of the heating wire (15) are led out through conductive extension areas and connected to the heating electrode (16), and the heating electrode (16) is connected to the control interface; The drive unit includes a control electrode (13), an array nozzle (6), and a boss electrode (14) surrounding each nozzle; each boss electrode (14) is controlled by the control electrode (13), and the opening and closing of the array nozzle (6) is controlled by the voltage of the control electrode (16). The decision is made that when a designated nozzle is in operation, the host computer outputs a command and controls the voltage. In addition, the host computer dynamically adjusts the heating voltage through the control interface based on the temperature feedback and working status of the electro-hydraulic nozzle. ; When the nozzle is in spray mode, a PID closed-loop algorithm is used to control the voltage. Maintain the ink temperature within the preset window; reduce the heating voltage when the printhead is in standby or during intermittent operation. Avoid localized overheating; heating voltage With driving voltage All of these are controlled by the coding program on the host computer.

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