Circulating ink supply system

Abstract

The invention belongs to the technical field of ink-jet printing, and particularly relates to a circulating ink supply system which comprises a first pressure supply mechanism, a second pressure supply mechanism, a first ink box, a first ink supply pump, a second ink box, a third ink box, a spray head and a first ink box. Ink can be conveyed from the first ink box to the second ink box under the action of the first ink supply pump, then the ink can be conveyed to the spray head after passing through the third ink box under the action of the gravity of the ink, and the gravity serves as power for ink supply in the process. Then ink in the spray head can flow back to the first ink box under the action of the negative pressure difference between the first ink box and the third ink box, in the process, the negative pressure difference serves as backflow power, and compared with a mechanical pump, the gravity and the negative pressure difference serve as power, negative pressure fluctuation of the ink cannot be generated, so that the stability of the ink in the circulation process is improved, and the service life of the ink is prolonged. Therefore, the problems of ink interruption, ink dripping and the like of the nozzle can be avoided, and printing quality is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of inkjet printing, and particularly to a circulating ink supply system. Background Art

[0002] In traditional industrial printing processes, ink is often supplied to the print head in a circulating manner. Currently, most circulating ink supplies use a mechanical pump as the power source for circulation. Since the mechanical pump generates vibrations during ink pumping, it is likely to cause negative pressure fluctuations in the entire circulation loop, resulting in problems such as ink breakage and dripping at the print head, which affect the printing quality.

[0003] Therefore, the above problems need to be solved urgently. Summary of the Invention

[0004] The purpose of the present invention is to provide a circulating ink supply system to avoid the phenomenon of unstable negative pressure during ink pumping by a mechanical pump, thereby improving the printing quality.

[0005] To achieve this purpose, the present invention adopts the following technical solutions:

[0006] A circulating ink supply system, comprising:

[0007] A first ink cartridge, a first ink supply pump, a second ink cartridge, a third ink cartridge, a print head, and the first ink cartridge are sequentially connected through an ink pipe. The first ink supply pump is used to transport the ink in the first ink cartridge to the second ink cartridge; the second ink cartridge is disposed above the third ink cartridge, so that the ink in the second ink cartridge flows from the second ink cartridge to the third ink cartridge under the action of its own gravity.

[0008] A first pressure supply mechanism, which is communicated with the first ink cartridge and is used to apply a first negative pressure to the inside of the first ink cartridge.

[0009] A second pressure supply mechanism, which is communicated with the third ink cartridge and is used to apply a second negative pressure with a pressure value lower than the first negative pressure to the inside of the third ink cartridge, so as to form a negative pressure difference for returning the ink in the print head to the first ink cartridge.

[0010] Preferably, the circulating ink supply system further includes a degassing structure, which is disposed between the first ink supply pump and the first ink cartridge, and the degassing structure is used to remove the bubbles in the ink.

[0011] Preferably, a one-way valve is disposed between the second ink cartridge and the third ink cartridge, and the one-way valve is used to restrict the ink in the third ink cartridge from flowing back to the second ink cartridge.

[0012] Preferably, the circulating ink supply system further includes:

[0013] A flow detector is arranged between the third ink cartridge and the print head and is used to detect the flow value of the ink flowing to the print head;

[0014] An ink path control module is electrically connected to the first pressure supply mechanism, the second pressure supply mechanism and the flow detector. The ink path control module is used to change the negative pressure difference based on the flow value so as to adjust the flow rate of the ink.

[0015] Preferably, a first liquid level detector electrically connected to the ink path control module is arranged inside each of the first ink cartridge and the third ink cartridge. The first liquid level detector is used to detect the liquid level height inside the first ink cartridge or the third ink cartridge;

[0016] The ink path control module is electrically connected to the first ink supply pump. The ink path control module is used to adjust the power of the first ink supply pump based on the liquid level heights of the first ink cartridge and the third ink cartridge so that the liquid level heights of the first ink cartridge and the third ink cartridge are at the same height.

[0017] Preferably, a second liquid level detector electrically connected to the ink path control module is arranged inside the second ink cartridge. The second liquid level detector is used to detect the lowest liquid level height and the highest liquid level height inside the second ink cartridge;

[0018] The circulating ink supply system further includes:

[0019] A fourth ink cartridge, which is communicated with the first ink cartridge;

[0020] A second ink supply pump is arranged between the fourth ink cartridge and the first ink cartridge and is used to convey the ink in the fourth ink cartridge to the first ink cartridge;

[0021] A first electromagnetic valve electrically connected to the control module is arranged between the first ink supply pump and the second ink cartridge. The first electromagnetic valve is used to open and close the ink pipe between the first ink supply pump and the second ink cartridge;

[0022] A second electromagnetic valve electrically connected to the control module is arranged between the first ink cartridge and the second ink supply pump. The second electromagnetic valve is used to open and close the ink pipe between the first ink cartridge and the second ink supply pump.

[0023] Preferably, the circulating ink supply system further includes:

[0024] A temperature detection part is arranged on the ink flow path and is used to detect the actual temperature values of the ink at different positions;

[0025] A heating part is arranged on the ink flow path and is used to heat the ink;

[0026] A temperature control module, electrically connected to the temperature detection unit and the heating unit, is configured to adjust the heating power of the heating unit based on the actual temperature value so that the ink remains at a preset temperature during the flowing process.

[0027] Preferably, the heating unit includes heating wires disposed on the ink tube, the first ink cartridge, the second ink cartridge, the third ink cartridge, and the print head.

[0028] Preferably, the first pressure supply mechanism or the second pressure supply mechanism includes:

[0029] A negative pressure source, communicated with the first ink cartridge or the third ink cartridge;

[0030] A buffer tank, disposed between the negative pressure source and the first ink cartridge or between the negative pressure source and the third ink cartridge to buffer the negative pressure in the ink tube.

[0031] Preferably, the first pressure supply mechanism or the second pressure supply mechanism further includes a positive pressure source, communicated with the buffer tank to deliver positive pressure into the first ink cartridge and the third ink cartridge.

[0032] Advantages of the present invention:

[0033] In the circulating ink supply system of the present invention, under the action of the first ink supply pump, the ink can be transported from the first ink cartridge to the second ink cartridge, and then under the action of the gravity of the ink itself, it can be transported to the print head after passing through the third ink cartridge. In this process, gravity is used as the power for ink supply. Compared with a mechanical pump, using gravity as the power will not cause negative pressure fluctuations, so as to improve the stability during the ink supply process, thereby avoiding problems such as ink breakage and ink dripping at the print head. And the setting of the second ink cartridge can prevent the negative pressure fluctuations generated during the ink pumping process by the first ink supply pump from affecting the ink between the third ink cartridge and the print head, further avoiding problems such as ink breakage and ink dripping at the print head. Subsequently, under the action of the negative pressure difference between the first ink cartridge and the third ink cartridge, the ink in the print head can be refluxed to the first ink cartridge. In this process, the negative pressure difference is used as the power for reflux. Compared with a mechanical pump, using the negative pressure difference as the power will not cause negative pressure fluctuations to the ink either, so as to improve the stability during the reflux process, and further avoid problems such as ink breakage and ink dripping at the print head, improving the printing quality. Description of the Drawings

[0034] Figure 1 It is a schematic structural diagram of the circulating ink supply system in an embodiment of the present invention.

[0035] In the figure:

[0036] 100, ink tube; 200, air tube;

[0037] 1. First ink cartridge; 2. First ink supply pump; 3. Second ink cartridge; 4. Third ink cartridge; 5. Printhead; 6. First pressure supply mechanism;

[0038] 7. Second pressure supply mechanism; 71. Negative pressure source; 72. Buffer tank;

[0039] 8. Degassing structure; 9. Check valve; 10. Flow detector; 11. First liquid level detector; 12. Second liquid level detector; 13. Fourth ink cartridge; 14. Second ink supply pump; 15. First solenoid valve; 16. Second solenoid valve; 17. Temperature detection part; 18. Heating part; 19. Temperature control module; 20. First ink filter; 21. First air pipe; 22. First air filter; 23. Second ink filter; 24. Second air pipe; 25. Second air filter; 26. Third air filter. Detailed implementation manners

[0040] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. Additionally, it should be noted that for the sake of description, only the parts related to the present invention are shown in the drawings, rather than all the structures.

[0041] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected to", and "fixed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features between them. Moreover, the first feature being "above", "above the top of", and "on the top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "below the bottom of", and "under the bottom of" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0043] In the description of this embodiment, the orientation or positional relationships such as "upper", "lower", "left", "right", etc. are based on the orientation or positional relationships shown in the drawings. They are only for the convenience of description and simplifying the operations, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0044] Please refer to Figure 1 , in this embodiment, a circulating ink supply system is proposed, which includes a first ink cartridge 1, a first ink supply pump 2, a second ink cartridge 3, a third ink cartridge 4, a print head 5, and a first ink cartridge 1 connected in sequence through an ink tube 100. The flow path of the ink is as shown by the solid arrow in Figure 1 . The first ink cartridge 1, the second ink cartridge 3, and the third ink cartridge 4 are all ink cartridges for containing ink in the prior art, and their specific structures are the prior art and will not be elaborated here. One end of the top of the print head 5 has an ink inlet of the print head 5 communicating with the third ink cartridge 4, and the other end has an ink outlet of the print head 5 communicating with the first ink cartridge 1. The bottom of the print head 5 has a print nozzle for inkjetting. The first ink supply pump 2 is used to transport the ink in the first ink cartridge 1 to the second ink cartridge 3; the second ink cartridge 3 is arranged above the third ink cartridge 4 so that the ink in the second ink cartridge 3 flows from the second ink cartridge 3 to the third ink cartridge 4 under the action of its own gravity; the circulating ink supply system further includes a first pressure supply mechanism 6 and a second pressure supply mechanism 7. The first pressure supply mechanism 6 communicates with the first ink cartridge 1 and is used to apply a first negative pressure to the inside of the first ink cartridge 1; the second pressure supply mechanism 7 communicates with the third ink cartridge 4 and is used to apply a second negative pressure with a pressure value lower than the first negative pressure to the inside of the third ink cartridge 4 to form a negative pressure difference for returning the ink in the print head 5 to the first ink cartridge 1. The negative pressure difference is preferably 0.6 to 1 KPa, and the specific value can be adjusted according to the actual printing requirements and will not be specifically limited here.

[0045] It can be understood that under the action of the first ink supply pump 2, ink can be transported from the first ink cartridge 1 to the second ink cartridge 3, and then under the action of the gravity of the ink itself, it can be transported to the nozzle 5 after passing through the third ink cartridge 4. In this process, gravity is used as the power for ink supply. Compared with a mechanical pump, using gravity as the power will not cause negative pressure fluctuations, so as to improve the stability during the ink supply process, thereby avoiding problems such as ink breakage and dripping at the nozzle 5. In addition, the setting of the second ink cartridge 3 can prevent the negative pressure fluctuations generated by the first ink supply pump 2 during the ink pumping process from affecting the ink between the third ink cartridge 4 and the nozzle 5, further avoiding problems such as ink breakage and dripping at the nozzle 5. Subsequently, under the action of the negative pressure difference between the first ink cartridge 1 and the third ink cartridge 4, the ink in the nozzle 5 can be circulated to the first ink cartridge 1. In this process, the negative pressure difference is used as the power for the return flow. Compared with a mechanical pump, using the negative pressure difference as the power will not cause negative pressure fluctuations in the ink either, so as to improve the stability during the return flow process, and further avoid problems such as ink breakage and dripping at the nozzle 5, improving the printing quality. In addition, using the gravity of the ink itself and the negative pressure difference between the first ink cartridge 1 and the third ink cartridge 4 as the power, compared with traditional mechanical pumps, will not generate additional noise, thus reducing noise pollution. And to further reduce the noise generated by the entire circulating ink supply system, the first ink supply pump 2 is preferably a peristaltic pump with a relatively low noise in the prior art. The specific structure of the peristaltic pump is the prior art and will not be elaborated here.

[0046] Further, a one-way valve 9 is provided between the second ink cartridge 3 and the third ink cartridge 4. The one-way valve 9 is used to restrict the ink in the third ink cartridge 4 from flowing back to the second ink cartridge 3. It can be understood that when the second pressure supply mechanism 7 applies a second negative pressure to the third ink cartridge 4, the provided one-way cut-off valve can prevent the ink in the third ink cartridge 4 from flowing back to the second ink cartridge 3 when the negative pressure value in the third ink cartridge 4 is too high, thereby ensuring the stability during the ink supply process.

[0047] In addition, a first ink filter 20 is provided between the third ink cartridge 4 and the nozzle 5. The first ink filter 20 is preferably a 10um - specification butterfly ink filter in the prior art, so as to filter impurities in the ink path and protect the nozzle 5 from being blocked by large particles.

[0048] In this embodiment, the circulating ink supply system further includes a degassing structure 8. The degassing structure 8 is arranged between the first ink supply pump 2 and the first ink cartridge 1, and the degassing structure 8 is used to remove bubbles in the ink. It can be understood that during the process of the ink being transported from the first ink cartridge 1 to the second ink cartridge 3, passing through the degassing structure 8 can remove the bubbles doped in the ink, thereby preventing the bubbles from being ejected from the nozzle 5 along with the ink, and further improving the printing quality.

[0049] Among them, the degassing structure 8 is preferably a columnar degassing lung in the prior art. The ink inlet of the degassing lung is communicated with the ink outlet of the first ink cartridge 1 through an ink pipe 100. The ink outlet of the degassing lung is communicated with the ink inlet of the second ink cartridge 3. The air inlet of the degassing lung is communicated with the first pressure supply mechanism 6 through an air pipe 200. The first pressure supply mechanism 6 can apply negative pressure to the degassing lung, and its gas path is as shown by the dotted arrow in Figure 1 to reduce the pressure inside the degassing lung, making it easier for gas to separate from the ink to achieve the removal of bubbles. In some other feasible embodiments, the degassing structure 8 can also be an ultrasonic degasser in the prior art, and its specific structure is the prior art and will not be elaborated here.

[0050] Furthermore, the ink inlet of the second ink cartridge 3 is at the top of the second ink cartridge 3, and a first air exchange pipe 21 is also provided at the top of the second ink cartridge 3. A first air filter 22 is provided on the first air exchange pipe 21. It can be understood that during the process of ink entering the second ink cartridge 3 from the ink inlet, the residual bubbles in the ink can be precipitated under the action of the height difference and then discharged from the second ink cartridge 3 through the first air exchange pipe 21, further improving the degassing effect of the ink. In addition, the setting of the first air exchange pipe 21 can maintain the air pressure inside the second ink cartridge 3 in a stable state to ensure the stability of the ink during transportation. The function of the first air filter 22 is to prevent external impurities from entering the inside of the second ink cartridge 3 through the first air exchange pipe 21.

[0051] In this embodiment, the circulating ink supply system further includes a flow detector 10 and an ink path control module. The flow detector 10 is arranged between the third ink cartridge 4 and the print head 5 and is used to detect the flow value of the ink flowing to the print head 5. The ink path control module is electrically connected to the first pressure supply mechanism 6, the second pressure supply mechanism 7, and the flow detector 10. The ink path control module is used to change the negative pressure difference based on the flow value to adjust the flow rate of the ink. It can be understood that according to the actual printing needs, a flow threshold is set. The actual flow value of the ink flowing to the print head 5 is detected by the flow detector 10. If the actual flow value is lower than the flow threshold, the ink path control module sends signals to the first pressure supply mechanism 6 and the second pressure supply mechanism 7. By adjusting the values of the first negative pressure and the second negative pressure, the negative pressure difference is increased, thereby improving the power of the backflow and further increasing the flow rate of the ink. On the contrary, if the actual flow value is higher than the flow threshold, the ink path control module sends signals to the first pressure supply mechanism 6 and the second pressure supply mechanism 7. By adjusting the values of the first negative pressure and the second negative pressure, the negative pressure difference is reduced, thereby reducing the power of the backflow and further reducing the flow rate of the ink. The ink path control module is preferably a PLC controller in the prior art, and the flow detector 10 is a clamp-type flow detector in the prior art.

[0052] Further, a first liquid level detector 11 electrically connected to the ink path control module is provided inside each of the first ink cartridge 1 and the third ink cartridge 4. The first liquid level detector 11 is used to detect the liquid level height inside the first ink cartridge 1 or the third ink cartridge 4. The ink path control module is electrically connected to the first ink supply pump 2. The ink path control module is used to adjust the power of the first ink supply pump 2 based on the liquid level heights of the first ink cartridge 1 and the third ink cartridge 4, so that the liquid level heights of the first ink cartridge 1 and the third ink cartridge 4 are at the same height. It can be understood that a communicating vessel structure is formed between the first ink cartridge 1 and the second ink cartridge 3 through the ink tube 100 and the print head 5. Based on the characteristics of the communicating vessel, the ink inside the first ink cartridge 1 and the second ink cartridge 3 can be maintained at the same horizontal height under the action of gravity, pressure, etc., which is likely to affect the ink reflux. Therefore, in this embodiment, during the ink pumping process of the first ink supply pump 2, the first liquid level detector 11 can detect the liquid level heights inside the first ink cartridge 1 and the second ink cartridge 3. By adjusting the power of the first ink supply pump 2, the liquid level heights inside the first ink cartridge 1 and the second ink cartridge 3 can be kept consistent, so as to further improve the stability of the circulating ink supply system and improve the ink supply efficiency.

[0053] Further, a second liquid level detector 12 electrically connected to the ink path control module is disposed inside the second ink cartridge 3. The second liquid level detector 12 is used to detect the lowest liquid level height and the highest liquid level height inside the second ink cartridge 3. The circulating ink supply system further includes a fourth ink cartridge 13, a second ink supply pump 14, a first solenoid valve 15, and a second solenoid valve 16. The fourth ink cartridge 13 is connected to the first ink cartridge 1. The second ink supply pump 14 is disposed between the fourth ink cartridge 13 and the first ink cartridge 1 and is used to transport the ink in the fourth ink cartridge 13 to the first ink cartridge 1. The first solenoid valve 15 is electrically connected to the control module. The first solenoid valve 15 is disposed between the first ink supply pump 2 and the second ink cartridge 3. The first solenoid valve 15 is used to open and close the ink pipe 100 between the first ink supply pump 2 and the second ink cartridge 3. The second solenoid valve 16 is electrically connected to the control module. The second solenoid valve 16 is disposed between the first ink cartridge 1 and the second ink supply pump 14. The second solenoid valve 16 is used to open and close the ink pipe 100 between the first ink cartridge 1 and the second ink supply pump 14. It can be understood that during the ink supply process, the ink inside the first ink cartridge 1 comes from two sources. One is the ink supplied from the fourth ink cartridge 13 to the first ink cartridge 1, and the other is the ink that flows back to the first ink cartridge 1 through the negative pressure difference. To ensure that the ink levels inside the first ink cartridge 1 and the third ink cartridge 4 are at the same height, it is necessary to transport the ink from the first ink cartridge 1 to the second ink cartridge 3 through the first ink supply pump 2, and the second ink cartridge 3 serves as a temporary buffer. When the second liquid level detector 12 detects that the liquid level height inside the second ink cartridge 3 reaches the highest liquid level height, it sends a signal to the ink path control module. The ink path control module can control the first solenoid valve 15 and the second solenoid valve 16 to disconnect the ink pipe 100. That is, the fourth ink cartridge 13 stops supplying ink to the first ink cartridge 1, the first ink cartridge 1 stops sending ink to the second ink cartridge 3, and the ink in the second ink cartridge 3 can enter the third ink cartridge 4 under the action of its own gravity. The ink in the print head 5 can be circulated to the first ink cartridge 1 under the action of the negative pressure difference, and the liquid level heights inside the first ink cartridge 1 and the third ink cartridge 4 can be at the same height under the combined action of the first liquid level detector 11 and the ink path control module to ensure the stability of the circulating ink supply system. In addition, the ink can be transported under the action of gravity and pressure difference. During this process, the first ink supply pump 2 and the second ink supply pump 14 can be temporarily turned off, thereby effectively alleviating the problem that the first ink supply pump 2 and the second ink supply pump 14 become hot and burned due to long-term operation, greatly reducing the material damage rate and significantly saving the material cost. In this embodiment, the second ink supply pump 14 is preferably a peristaltic pump with a relatively low noise in the prior art to further reduce the noise of the entire circulating ink supply system.

[0054] In addition, a second ink filter 23 is provided between the fourth ink cartridge 13 and the second ink supply pump 14. A third ink filter 26 is also provided on the ink tube 100 connected to the ink inlet of the fourth ink cartridge 13. Both the second ink filter 23 and the third ink filter 26 are preferably 10um specification butterfly ink filters in the prior art to prevent particulate matters such as impurities from entering the circulating ink path.

[0055] It is worth noting that the ink inlet of the fourth ink cartridge 13 is located at the top of the fourth ink cartridge 13 and is connected to an external ink supply mechanism through the ink tube 100. A second air exchange tube 24 is also provided at the top of the fourth ink cartridge 13, and a second air filter 25 is provided on the second air exchange tube 24. It can be understood that the external ink supply mechanism supplies ink to the fourth ink cartridge 13 through the ink tube 100. Under the action of the height difference, the air bubbles in the ink can be separated out and then discharged from the fourth ink cartridge 13 through the second air exchange tube 24, further improving the degassing effect of the ink. In addition, the setting of the second air exchange tube 24 can keep the air pressure inside the fourth ink cartridge 13 stable to ensure the stability of the ink during transportation. The function of the second air filter 25 is to prevent external impurities from entering the interior of the second ink cartridge 3 through the second air exchange tube 24. Among them, the volume of the fourth ink cartridge 13 is preferably 500 ml, and the volumes of the first ink cartridge 1, the second ink cartridge 3, and the third ink cartridge 4 are all 150 ml. With such a setting, it is possible to ensure that ink replenishment is not required during long-term printing.

[0056] In this embodiment, the specific structures of the first pressure supply mechanism 6 and the second pressure supply mechanism 7 are the same. Here, the second pressure supply mechanism 7 is taken as an example for description. The second pressure supply mechanism 7 includes a negative pressure source 71 and a buffer tank 72. The negative pressure source 71 is connected to the first ink cartridge 1 or the third ink cartridge 4; the buffer tank 72 is arranged between the negative pressure source 71 and the first ink cartridge 1 or between the negative pressure source 71 and the third ink cartridge 4 to buffer the negative pressure in the ink tube 100. It can be understood that during the process of supplying negative pressure to the first ink cartridge 1 and the second ink cartridge 3, the setting of the buffer tank 72 can reduce the influence of the decrease in air pressure in the first ink cartridge 1 or the second ink cartridge 3 on the ink path, so as to prevent negative pressure fluctuations from occurring inside the ink tube 100, thereby further improving the stability of the ink path.

[0057] During the printing process, if there are still air bubbles remaining inside the print head 5, it will affect the printing effect. Therefore, in this embodiment, the second pressure supply mechanism 7 further includes a positive pressure source, which is connected to the buffer tank 72 to supply positive pressure to the first ink cartridge 1 and the third ink cartridge 4. It can be understood that by supplying positive pressure to the first ink cartridge 1 and the third ink cartridge 4 through the positive pressure source, under the action of the positive pressure, the ink in the print head 5 can be discharged from the print nozzle. After the air bubbles are exhausted, printing can start again.

[0058] Conventionally, industrial printing nozzles 5 generally only support inks with viscosities of 5 to 12 centipoise (cp) at room temperature, and the upper limit of some models only reaches 30 cp. For high-viscosity solvents with viscosities exceeding 30 cp at room temperature, they need to be heated to about 60 to 80 °C during use. Therefore, the circulating ink supply system in this embodiment further includes a temperature detection unit 17, a heating unit 18, and a temperature control module 19 to achieve full-range heat preservation on the flow path, so that the circulating ink supply system can transport solvents with different viscosities.

[0059] Specifically, the temperature detection unit 17 is arranged on the ink flow path and is used to detect the actual temperature values of the ink at different positions; the heating unit 18 is arranged on the ink flow path and is used to heat the ink; the temperature control module 19 is electrically connected to the temperature detection unit 17 and the heating unit 18, and is used to adjust the heating power of the heating unit 18 based on the actual temperature value, so that the ink remains at a preset temperature during the flow process. It can be understood that the above-mentioned flow path means that the ink flows from the fourth ink cartridge 13 through the ink pipe 100 to the first ink cartridge 1, from the first ink cartridge 1 through the ink pipe 100 to the second ink cartridge 3, from the second ink cartridge 3 through the ink pipe 100 to the third ink cartridge 4, from the third ink cartridge 4 through the ink pipe 100 to the nozzle 5, part of the ink is ejected from the print head for printing, and the remaining ink flows back to the first ink cartridge 1 through the ink pipe 100. The heating unit 18 is provided on the ink pipe 100, the first ink cartridge 1, the second ink cartridge 3, the third ink cartridge 4, and the nozzle 5, and the temperature detection unit 17 is provided on the first ink cartridge 1, the second ink cartridge 3, the third ink cartridge 4, and the nozzle 5. With such a setting, the temperature detection unit 17 can detect the ink temperature at different positions and transmit the detection results to the temperature control module 19. Based on the detection results, the temperature control module 19 can control the heating unit 18 to heat the ink or stop heating the ink. Among them, the temperature control module 19 is preferably a temperature control board card in the prior art to achieve precise temperature control.

[0060] Specifically in this embodiment, for the ink cartridges (including the first ink cartridge 1, the second ink cartridge 3, the third ink cartridge 4, and the fourth ink cartridge 13), the ink cartridges are preferably black light-shielding cartridges treated by aluminum anodization. The heating unit 18 includes a heating wire and a substrate. Substrates are provided on each side wall of the ink cartridge, and the heating wire is embedded inside the substrate. Through the heat conduction of the substrate and the side wall of the ink cartridge, the ink inside the ink cartridge is heated. Among them, the heating wire is preferably a nickel-chromium alloy heating wire, and the substrate is preferably a ceramic substrate. Such a setting can ensure the stability of temperature during transmission.

[0061] The temperature detection unit 17 includes a temperature sensor, and the detection end of the temperature sensor is clamped between the substrate and the side wall of the ink cartridge to detect the temperature of the ink inside the ink cartridge.

[0062] For the pipeline, the ink pipe 100 is preferably a Teflon high-temperature resistant black ink pipe 100 to avoid damage to the ink pipe 100 caused by high temperature and improve safety performance. The heating part 18 includes a heating wire and heat-insulating cotton. The heating wire is wound around the outside of the ink pipe 100 and is wrapped by the heat-insulating cotton to ensure the heating performance. Among them, the heating wire is preferably a nickel-chromium alloy heating wire, and the heat-insulating cotton is preferably an insulating and high-temperature resistant aerogel heat-insulating cotton.

[0063] For the nozzle 5, the heating part 18 includes a heating wire and a substrate. Substrates are arranged on each side wall of the nozzle 5. The heating wire is embedded inside the substrate, and the ink inside the nozzle 5 is heated through the heat conduction of the substrate and the side wall of the nozzle 5, so that there is no need to integrate a heating structure inside the nozzle 5. Among them, the heating wire is preferably a nickel-chromium alloy heating wire, and the substrate is preferably a ceramic substrate. Such an arrangement can ensure the stability of the temperature during transmission.

[0064] The temperature detection part 17 includes two temperature sensors. One is arranged on the ink pipe 100 connecting the ink inlet of the nozzle 5, and the other is arranged on the ink pipe 100 at the ink outlet of the nozzle 5. The temperature of the ink inside the nozzle 5 can be obtained through the difference between the two temperature sensors, so as to facilitate the heating part 18 to heat the nozzle 5.

[0065] Obviously, the above-mentioned embodiments of the present invention are only examples for clearly explaining the present invention, and are not intended to limit the implementation manners of the present invention. For those of ordinary skill in the art, various obvious changes, re-adjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A circulating ink supply system, characterized in that, Including: The first ink cartridge (1), the first ink supply pump (2), the second ink cartridge (3), the third ink cartridge (4), the nozzle (5) and the first ink cartridge (1) are sequentially connected through an ink pipe (100). The first ink supply pump (2) is used to transport the ink in the first ink cartridge (1) to the second ink cartridge (3). The second ink cartridge (3) is arranged above the third ink cartridge (4) so that the ink in the second ink cartridge (3) flows from the second ink cartridge (3) to the third ink cartridge (4) under the action of its own gravity. The first pressure supply mechanism (6) is communicated with the first ink cartridge (1) and is used to apply a first negative pressure to the inside of the first ink cartridge (1). The second pressure supply mechanism (7) is communicated with the third ink cartridge (4) and is used to apply a second negative pressure with a pressure value lower than the first negative pressure to the inside of the third ink cartridge (4) to form a negative pressure difference for returning the ink in the nozzle (5) to the first ink cartridge (1).

2. The circulating ink supply system according to claim 1, wherein The circulating ink supply system further includes a degassing structure (8). The degassing structure (8) is arranged between the first ink supply pump (2) and the first ink cartridge (1), and the degassing structure (8) is used to remove the bubbles in the ink.

3. The circulating ink supply system according to claim 1, wherein, A one-way valve (9) is arranged between the second ink cartridge (3) and the third ink cartridge (4). The one-way valve (9) is used to restrict the ink in the third ink cartridge (4) from flowing back to the second ink cartridge (3).

4. The circulating ink supply system according to claim 1, characterized in that The circulating ink supply system further includes: A flow detector (10) is arranged between the third ink cartridge (4) and the nozzle (5) and is used to detect the flow value of the ink flowing to the nozzle (5). An ink path control module is electrically connected to the first pressure supply mechanism (6), the second pressure supply mechanism (7) and the flow detector (10). The ink path control module is used to change the negative pressure difference based on the flow value to adjust the flow rate of the ink.

5. The circulating ink supply system according to claim 4, characterized in that, First liquid level detectors (11) electrically connected to the ink path control module are arranged inside the first ink cartridge (1) and the third ink cartridge (4). The first liquid level detectors (11) are used to detect the liquid level height inside the first ink cartridge (1) or the third ink cartridge (4). The ink path control module is electrically connected to the first ink supply pump (2). The ink path control module is used to adjust the power of the first ink supply pump (2) based on the liquid level heights of the first ink cartridge (1) and the third ink cartridge (4) so that the liquid level heights of the first ink cartridge (1) and the third ink cartridge (4) are at the same height.

6. The circulating ink supply system according to claim 5, characterized in that, A second liquid level detector (12) electrically connected to the ink path control module is arranged inside the second ink cartridge (3). The second liquid level detector (12) is used to detect the lowest liquid level height and the highest liquid level height inside the second ink cartridge (3). The circulating ink supply system further includes: A fourth ink cartridge (13) is communicated with the first ink cartridge (1). A second ink supply pump (14) is arranged between the fourth ink cartridge (13) and the first ink cartridge (1) and is used to transport the ink in the fourth ink cartridge (13) to the first ink cartridge (1). A first solenoid valve (15) electrically connected to the control module, the first solenoid valve (15) being disposed between the first ink supply pump (2) and the second ink cartridge (3), the first solenoid valve (15) being configured to open and close an ink tube (100) between the first ink supply pump (2) and the second ink cartridge (3); A second solenoid valve (16) electrically connected to the control module, the second solenoid valve (16) being disposed between the first ink cartridge (1) and the second ink supply pump (14), the second solenoid valve (16) being configured to open and close an ink tube (100) between the first ink cartridge (1) and the second ink supply pump (14).

7. The circulating ink supply system according to claim 1, wherein The circulating ink supply system further includes: A temperature detection unit (17) disposed on the flow path of the ink and configured to detect an actual temperature value of the ink at different positions; A heating unit (18) disposed on the flow path of the ink and configured to heat the ink; A temperature control module (19) electrically connected to the temperature detection unit (17) and the heating unit (18), configured to adjust the heating power of the heating unit (18) based on the actual temperature value so that the ink remains at a preset temperature during the flow process.

8. The circulating ink supply system according to claim 7, characterized in that, The heating unit (18) includes heating wires disposed on the ink tube (100), the first ink cartridge (1), the second ink cartridge (3), the third ink cartridge (4), and the print head (5).

9. The circulating ink supply system according to claim 1, wherein The first pressure supply mechanism (6) or the second pressure supply mechanism (7) includes: A negative pressure source (71) communicating with the first ink cartridge (1) or the third ink cartridge (4); A buffer tank (72) disposed between the negative pressure source (71) and the first ink cartridge (1) or disposed between the negative pressure source (71) and the third ink cartridge (4) to buffer the negative pressure in the ink tube (100).

10. The circulating ink supply system according to claim 9, wherein The first pressure supply mechanism (6) or the second pressure supply mechanism (7) further includes a positive pressure source communicating with the buffer tank (72) to supply positive pressure to the first ink cartridge (1) and the third ink cartridge (4).

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