A reduction ink path for a liquid metal ink supply system

Abstract

The present invention provides a reduction ink path of a liquid metal ink supply system, comprising an ink tube, a reduction filter and a print head; the ink tube connects a liquid metal ink cartridge and the print head to form an ink path; the reduction filter is connected to the ink path and has a cavity, in which an oxide removal solution is contained, so that the oxide in the liquid metal flowing to the print head through the reduction filter is reduced. By adding an oxide removal solution to the ink path to filter the oxide in the liquid metal, the liquid metal flowing into the print head has a higher quality, thereby ensuring the ink output quality of the liquid metal print head.

Description

Technical Field

[0001] The invention relates to a reduction ink path of a liquid metal ink supply system, which is mainly used in the ink supply system of a liquid metal printer. Background Art

[0002] With the continuous advancement of printed electronics technology, conductive fluids represented by liquid metal have emerged, making it possible to print wires to make liquid metal flexible electronic circuits. This has not only changed the traditional PCB (printed circuit board) hard electronic circuit manufacturing model, but also greatly reduced the time and cost of electronic circuit manufacturing. Liquid metal printing technology has unique advantages in the rapid manufacturing of flexible circuits, PCBs, antennas and other electronic devices, and has a very broad application prospect.

[0003] In existing liquid metal printing, liquid metal ink mainly uses its own gravity as the printing driving force, relying on the wetting and adhesion of liquid metal to the base material to achieve continuous ink discharge and line printing.

[0004] However, (1) as the liquid level of the liquid metal ink continues to decrease, the printing driving force becomes smaller, the amount of ink will decrease, and the width of the printed conductive line will become inconsistent; (2) the fluidity of liquid metal is greatly affected by temperature. Generally, as the temperature rises, the fluidity will improve, and vice versa. When the external ambient temperature changes, the fluidity of the liquid metal will change and the ink output will change; (3) as time goes by, the content of oxides in the liquid metal ink gradually increases. The more oxides there are, the worse the fluidity of the liquid metal will become, and the ink output will also be affected; (4) the existing printing method that relies on gravity flow cannot accurately control the flow of liquid metal, and the stability of the ink supply system itself and the consistency of the printed line width are difficult to guarantee; (5) when printing stops, the gravity of the metal ink will cause it to leak at the pen tip, which not only wastes liquid metal materials but also affects printing performance.

[0005] Therefore, the existing ink supply systems and methods greatly limit the scope of application of traditional liquid metal printing technology. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the problem of unstable quality of traditional liquid metal printing and improve the stability of printing line width. In particular, the reduction ink path of the liquid metal ink supply system of the printer is improved. By adding the reduction ink path, the printing environment is improved to ensure that the liquid metal flowing to the print head is basically free of oxides.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] It includes an ink tube, a reduction filter and a print head; the ink tube connects the liquid metal ink cartridge and the print head to form an ink path; the reduction filter is connected to the ink path and has a cavity, in which an oxide removal solution is contained, so that the oxide in the liquid metal flowing to the print head through the reduction filter is reduced.

[0009] It also includes a one-way valve connected to the ink path between the liquid metal ink cartridge and the reduction filter.

[0010] The utility model also comprises a one-way valve connected at the inlet of the reduction filter.

[0011] The inlet and outlet of the one-way valve are both sealed and connected to the ink tube using a Luer connector.

[0012] The inlet and outlet of the reduction filter are both sealed and connected to the ink tube using a pagoda joint.

[0013] The connection between the print head and the ink tube is thread-sealed using a knurled joint.

[0014] The oxide removal solution is one of NaOH, HCL, H2SO4, and KOH solutions, the volume of which does not exceed 40% of the cavity volume, and the concentration is 0.05mol / L-0.5mol / L.

[0015] Among them, the ink tube, Luer joint, pagoda joint and knurled joint are all made of plastic.

[0016] The beneficial effects of the present invention are:

[0017] By adding an oxide removal solution in the ink path to filter the oxides in the liquid metal, the quality of the liquid metal flowing into the print head is higher, thereby ensuring the ink output quality of the liquid metal print head. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the liquid metal ink supply system of the present invention;

[0019] Figure 2 A schematic diagram of an ink supply method of a liquid metal ink supply system of the present invention;

[0020] Figure 3A It is a schematic diagram of a temperature control component of a liquid metal ink supply system of the present invention;

[0021] Figure 3B A schematic diagram of a control method for a temperature control component of a liquid metal ink supply system of the present invention;

[0022] Figure 4A , 4B Schematic diagrams of two specific implementations of the oxide content testing assembly of the liquid metal ink supply system of the present invention;

[0023] Figure 5 It is a schematic diagram of a liquid level control component of a liquid metal ink supply system of the present invention;

[0024] Figure 6 A schematic diagram of an air pressure control component of a liquid metal ink supply system of the present invention;

[0025] Figure 7 A schematic diagram of a reduction ink path of a liquid metal ink supply system of the present invention;

[0026] Figure numerals: 1-gravity sensor, 2-liquid metal ink cartridge, 3-ink discharge joint, 4-ink supply joint, 5-check valve, 6-filter, 7-ink supply pump, 8-ink discharge pump, 9-ink pool, 10-ink tube, 13-negative pressure air pump, 14-positive pressure air pump, 15-pressure stabilizing gas cylinder, 16-valve block, 17-solenoid valve, 18-air pipe, 19-air pressure control board, 20-air pressure sensor, 21-control circuit, 22-atmosphere connection port, 24-reduction filter, 25, 28, 33-ink tube, 26, 27-Luer joint, 29, 32- Pagoda joint, 30-oxide removal solution, 31-reduced liquid metal, 34-knurled joint, 35-print head, 36, 37, 38, 40, 42-metal knurled joint, 39, 41-pagoda joint, 44-liquid metal cartridge cover, 11, 50-test cell, 12-viscosity measuring instrument, 43-Luer joint, 44-liquid metal cartridge cover, 47-resistance measuring instrument, 45, 48-test cell cover, 46, 49-tested liquid metal, 54-heating device, 55-temperature measuring device, 56-refrigeration device, 57-control device. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0028] See also Figure 1 The specific implementation manner shown is a liquid metal ink supply system, including a liquid metal ink cartridge 2, a temperature control component, a life counting component, an oxide test component, a liquid level control component, an air pressure control component, a reduction ink path, and a print head; the liquid metal ink cartridge 2 is connected to the reduction ink path and the oxide test component through two different ink tubes, respectively, and is connected to the air pressure control component through an air pipe 18; the ink discharge joint 3 and the ink supply joint 4 of the liquid level control component are directly connected to the liquid metal ink cartridge 2, and are in direct contact with the liquid metal, and its gravity sensor 1 is connected to the lower surface of the liquid metal ink cartridge 2; the temperature control component and the life counting component are connected to the outer surface of the liquid metal ink cartridge 2.

[0029] The liquid metal ink cartridge 2 also includes a liquid metal ink cartridge cover 44, and the air pipe 18, the ink discharge connector 3, and the ink supply connector 4 are connected to the liquid metal ink cartridge cover 44. The cover of the liquid metal ink cartridge ensures the sealed connection of other components with it, and also ensures the convenience of disassembly and assembly and the sealing of the entire liquid metal ink cartridge.

[0030] Wherein, the liquid metal used is also called low melting point metal, which includes low melting point metal element with melting point below 300 degrees Celsius, low melting point metal alloy or conductive nanofluid formed by mixing liquid metal element / low melting point metal alloy with metal nanoparticles and fluid dispersant. More specifically, when the conductive nanofluid is selected, the fluid dispersant is preferably one of ethanol, propylene glycol, glycerol, polyvinyl pyrrolidone, polydimethylsiloxane, polyethylene glycol, polymethyl methacrylate. In some embodiments, the low melting point metal alloy component may include one or more of gallium, indium, tin, zinc, silver, copper, iron, nickel, etc.

[0031] Preferably, the specific selection range of liquid metal includes: one or more of gallium element, gallium-indium alloy, gallium-indium-tin alloy, gallium-tin alloy, gallium-zinc alloy, gallium-indium-zinc alloy, gallium-tin-zinc alloy, and gallium-indium-tin-zinc alloy.

[0032] Two different ink tubes connected to the reduction ink path and the oxide test assembly are connected to the side wall of the liquid metal ink cartridge 2. The position of the ink tube on the side wall can be flexibly set according to the position of the reduction ink path and the oxide test assembly.

[0033] The air pressure control component is an electric air pressure source to realize the supply of air pressure.

[0034] The life counting component is a timing chip that is directly mounted on the liquid metal cartridge.

[0035] See also Figure 2 , the ink supply method of the ink supply system shown in the specific implementation manner is:

[0036] (1) The temperature control component is started to control the working temperature in the liquid metal ink cartridge to 21-26°C;

[0037] (2) The life counting component detects whether the liquid metal ink cartridge is in a normal working time state. If it exceeds the normal working time, the upper computer software of the ink supply system prompts the user to replace the ink cartridge. If it does not exceed the normal working time, the counting starts;

[0038] (3) The oxide content test component is started, the liquid metal in the liquid metal ink cartridge is sucked into the test pool, and the oxide mass percentage C is detected, and the value is fed back to the upper computer device of the ink supply system. When C>20%, the ink supply system fails, and the upper computer software prompts the user to replace the ink cartridge. When C≤20%, the life counting component starts counting;

[0039] (4) The liquid level control component is started to control the liquid level height in the liquid metal ink cartridge to always be -0.2 mm ≤ h-h0 ≤ 0.2 mm, where h is the liquid level height and h0 is the recommended liquid level height;

[0040] (5) The air pressure control component is started to control the air pressure in the liquid metal ink cartridge to be in a stable state;

[0041] (6) The ink supply system starts supplying ink for printing.

[0042] The air pressure control component and liquid level control component of the ink supply system have a fault self-detection function. When the continuous working time of the air pressure control component or the liquid level control component exceeds 10 minutes, it means that the air pressure or liquid level in the liquid metal ink cartridge is always in an unstable state. It is assumed that the relevant component is faulty, and the upper computer software of the ink supply system prompts the user of the system failure.

[0043] The normal working time of the life counting component of the ink supply system is 3 months.

[0044] The present invention defines the ink supply system and ink supply method of the liquid metal printer, so that a series of control components can work in sequence, eliminate system failures step by step, ensure the working stability of the ink supply system, and ensure the stability of the liquid metal in the liquid metal ink cartridge by starting each system in an orderly manner, so as to improve the printing line width and printing quality.

[0045] The temperature control component and its control method are to ensure that the printing temperature T of the liquid metal is always at the optimal preset temperature T0.

[0046] See also Figure 3A and 3B The specific implementation shows a temperature control method of a temperature control component of a liquid metal ink supply system, which uses a heating device 54, a cooling device 56, a temperature measuring device 55 and a control device 57 to control the printing temperature T of the liquid metal 49 in the liquid metal ink cartridge 2 according to the preset temperature T0 of the liquid metal; the heating device 54 and the cooling device 56 are located at the bottom of the liquid metal ink cartridge 2 and are in direct contact with the liquid metal 49; when T<T0, the heating device 54 is started, when T>T0, the cooling device 56 is started, and when T=T0, the temperature control component does not work.

[0047] According to the properties of liquid metal, in general, the preset temperature T0=21-26°C, and the control device in the temperature control method adopts a common PID control device.

[0048] The heating device 54 and the cooling device 56 also adopt common forms. The heating device 54 is any one of a heating rod, a polyimide heating film and a ceramic heating plate; the cooling device 56 is any one of a semiconductor cooling plate, water cooling and air cooling.

[0049] The main purpose of the temperature control method is to control the printing temperature, which is related to the installation position of the temperature measuring device. Figure 3A , shows an installation method of the temperature measuring device 55, which is located at the bottom of the liquid metal ink cartridge 2. At this time, the temperature measuring device 55 is in direct contact with the liquid metal 49, T = T c +T', where T is the printing temperature, T c To measure the temperature, T' is the temperature loss difference between the liquid metal ink cartridge 2 and the print head 35. This measurement method is indirect temperature measurement. The printing temperature of the liquid metal in the print head 35 is estimated by measuring the temperature of the liquid metal 49 in the liquid metal ink cartridge 2. Here, T' is mainly affected by the ambient temperature. Generally, the lower the ambient temperature, the greater T', and vice versa. Another installation method of the temperature measuring device 55, not shown in the figure, is located inside the print head 35. At this time, the temperature measuring device 55 is also in direct contact with the liquid metal, T = T c , where T is the printing temperature, T c To measure the temperature, this measurement method is direct temperature measurement, which directly obtains the printing temperature by measuring the temperature of the liquid metal in the print head 35. Of the above two temperature measurement methods, the indirect temperature measurement method is not as accurate as the direct temperature measurement method, but since the preset temperature T0 of the liquid metal is a temperature range, i.e., 21-26°C, both of the above two temperature measurement methods can be used.

[0050] Regarding the assembly method in the temperature control assembly, the heating device, the cooling device and the temperature measuring device are all fixedly connected to the wall of the liquid metal ink cartridge or the wall of the print head by means of threads or heat-resistant adhesive bonding.

[0051] It is worth noting that the temperature control component and its control method are to ensure that the liquid metal in the liquid metal ink cartridge is always at a suitable temperature for printing, so that the ink output of the liquid metal remains stable, which is conducive to the precise flow control of the ink supply system. If the temperature control component is repeatedly started or works for too long, it means that the temperature in the liquid metal ink cartridge cannot reach the preset temperature. Then the host computer of the ink supply system may determine that it has failed and prompt the user to check.

[0052] The life counting component is the prerequisite for ensuring the normal operation of the liquid metal ink supply system, ensuring that the liquid metal in the ink supply system always has good quality.

[0053] The cumulative use time of liquid metal ink cartridges is generally about three months. Each liquid metal ink cartridge has a separate anti-counterfeiting password number. When the user uses a new liquid metal ink cartridge for the first time, the anti-counterfeiting password number needs to be manually entered in the upper computer software operation interface. When the user operates the printer to start printing, the printer device is in working mode, and the upper computer software of the ink supply system starts timing. When the device ends, the timing also ends. When the timing reaches three months, the anti-counterfeiting password number becomes invalid, the upper computer software exits the normal operational interface, and prompts the user to replace the ink cartridge. In addition, when the oxide content test component of the liquid metal ink supply system detects that the mass percentage of oxides in the liquid metal ink cartridge is C>20%, the life counting component will also prompt the user to replace the ink cartridge through the upper computer software.

[0054] The life counting module board is installed at the bottom of the ink cartridge and fixed at the four corners by screws.

[0055] The oxide content test component in the ink supply system mainly realizes the measurement of the oxide mass percentage through the following principles: first, as the oxide in the liquid metal ink cartridge increases, the viscosity of the liquid metal will increase accordingly. By measuring the viscosity value of the liquid metal being tested, the size of the oxide mass percentage C is indirectly converted; second, as the oxide in the liquid metal ink cartridge increases, the resistance of the liquid metal will increase accordingly. By measuring the resistance value of the liquid metal being tested, the size of the oxide mass percentage C is indirectly calculated; third, as the oxide in the liquid metal ink cartridge increases, the weight of the liquid metal will increase accordingly. By measuring the mass value of the liquid metal being tested, the size of the oxide mass percentage C is indirectly calculated; fourth, as the oxide in the liquid metal ink cartridge increases, the electrical parameters at the same position in the liquid metal will change accordingly. By measuring the corresponding electrical parameter values ​​in the liquid metal being tested, the size of the oxide mass percentage C is indirectly calculated. In the above principle, the process of converting the measured value into the oxide mass percentage C is completed by the host computer of the liquid metal ink supply system.

[0056] See also Figure 3A and 3B , are two specific embodiments of the present invention, an oxide content test component of a liquid metal ink supply system, comprising a test cell 11 or 50, a test cell cover 45 or 48, a measuring instrument 12 or 47, a liquid metal 46 or 49 to be tested, and a feedback component; the measuring instrument 12 or 47 is fixedly mounted on the test cell cover 45 or 48, the lower end of the measuring instrument 12 or 47 is always in contact with the liquid metal 46 or 49 to be tested in the test cell 11 or 50, and the upper end of the measuring instrument 12 or 47 is exposed from the test cell cover 45 or 48; the feedback component is fixed at the upper end of the measuring instrument 12 or 47, and is connected to a host computer of the liquid metal ink supply system.

[0057] The test pool of the oxide content test assembly actually measures and feeds back the data in the liquid metal ink cartridge 2 in real time, and the two containers are interconnected. Therefore, the oxide content test assembly also includes a suction device, which is fixed to the side wall of the test pool 11 or 50 and connected to the liquid metal ink cartridge 2 of the liquid metal ink supply system through an ink tube, and sucks liquid metal from the liquid metal ink cartridge 2 into the test pool 11 or 50.

[0058] The feedback component can be in various forms. For example, the feedback component is a feedback circuit, which is fixedly connected to the upper end of the measuring instrument 12 or 47 and the upper computer of the liquid metal ink supply system, and feeds back the measured value of the measuring instrument 12 or 47. For another example, the feedback component is a wireless signal transmitter, which is fixed to the upper end of the measuring instrument 12 or 47 and sends a wireless signal of the measured value of the measuring instrument 12 or 47, and the upper computer of the liquid metal ink supply system receives the wireless signal.

[0059] The measuring instruments for the oxide content test kit can also be used in various forms. For example, see Figure 3A The measuring instrument in this embodiment is a viscosity measuring instrument 12, and the measuring principle adopted is: as the amount of oxide in the liquid metal ink cartridge increases, the viscosity of the liquid metal increases accordingly. By measuring the viscosity value of the liquid metal being measured, the mass percentage C of the oxide is indirectly calculated. For another example, see Figure 3B The measuring instrument in this embodiment is a resistance measuring instrument 47, and the measuring principle adopted is: as the oxide in the liquid metal ink cartridge increases, the resistance of the liquid metal increases accordingly, and by measuring the resistance value of the liquid metal being measured, the mass percentage C of the oxide is indirectly calculated. In addition, the measuring instrument can also be any one of a weight measuring instrument, a voltage measuring instrument, and a potential measuring instrument.

[0060] The measured value measured by the measuring instrument 12 or 47 is fed back to the host computer of the liquid metal ink supply system through the feedback component, and the host computer of the ink supply system obtains the oxide mass percentage C of the measured liquid metal 46 or 49 through numerical calculation and conversion.

[0061] The measuring instrument 12 or 47 is fixed on the test cell cover 45 or 48 in the following manner: threaded holes are drilled on the test cell cover 45 or 48 and threaded connection is achieved by cooperating with the fixing tool on the measuring instrument 12 or 47 .

[0062] The working principle of the liquid level control component is that the gravity sensor measures the weight of the entire liquid metal cartridge, then calculates the corresponding liquid level height, and then adjusts the liquid level according to demand.

[0063] Referring to FIG. 4 , a specific embodiment shows a liquid metal ink supply system liquid level control assembly, including a gravity sensor 1, a liquid metal ink cartridge 2, an ink discharge joint 3, an ink supply joint 4, an ink supply pump 7, an ink discharge pump 8, an ink pool 9, and an ink tube 10; the gravity sensor 1 is located below the liquid metal ink cartridge 2; the ink discharge joint 3 and the ink supply joint 4 are located above the liquid metal ink cartridge 2; the ink supply pump 7 and the ink discharge pump 8 are located in the ink pool 9, for supplying and discharging ink to the liquid metal ink cartridge 2; the ink tube 10 is connected between the ink pool 9 and the liquid metal ink cartridge 2 to form an ink supply channel and an ink discharge channel. In the liquid level control assembly, there are two interconnected containers, namely the liquid metal ink cartridge 2 and the ink pool 9, which ensures the continuous stability of the liquid level in the liquid metal ink cartridge 2 by monitoring the liquid level in the liquid metal ink cartridge 2 and inputting or outputting liquid metal from the ink pool 9.

[0064] In order to improve the purity of the liquid metal in the liquid metal ink cartridge 2, the liquid level control assembly further includes a one-way valve 5 and a filter 6, wherein the one-way valve 5 and the filter 6 are both arranged on the ink supply channel formed by the ink tube 10 connecting the ink pool 9 and the liquid metal ink cartridge 2. The positions of the two can be flexibly selected, and after the one-way valve 5 which is convenient to operate is arranged, the filter 6 can be arranged between the one-way valve 5 and the ink supply pump 7, or between the one-way valve 5 and the ink supply connector 4.

[0065] The liquid metal ink cartridge 2 also includes a liquid metal ink cartridge cover 44 above, and the two cooperate with each other to accommodate liquid metal. The ink discharge connector 3 and the ink supply connector 4 are fixed to the liquid metal ink cartridge cover 44 in a manner that allows for flexible installation and disassembly, such as a threaded connection.

[0066] The gravity sensor 1 is fixed to the bottom of the liquid metal ink cartridge 2 by gluing. The gravity sensor 1 is generally not connected to the liquid metal ink cartridge 2 by screws or bolts, because the inherent gravity of the screws or bolts will affect the measurement result of the gravity sensor.

[0067] Many sealing connectors are used in the liquid level control assembly to ensure the assembly and sealing between the various components. The Luer connector 43 is located at both ends of the one-way valve 5 and the filter 6, and at the connection between the ink discharge connector 3 and the ink supply connector 4 and the outer surface of the liquid metal ink cartridge cover 44. The pagoda connector is located at the two connections between the ink supply pump 7 and the ink discharge pump 8 and the ink tube 10.

[0068] The liquid level control component is used to monitor the liquid level in the liquid metal ink cartridge. Ensuring the liquid level actually ensures the quality of the liquid metal in the ink cartridge. The first step in controlling the liquid level height is to obtain the liquid level height. The liquid level control component converts the liquid level height h according to the weight G of the liquid metal ink cartridge 2 measured by the gravity sensor 1, and the host computer of the ink supply system can obtain the liquid level height h in the liquid metal ink cartridge 2 for real-time control; the conversion formula is h = (G-G0) / ρ sg, where h is the liquid level height, G is the weight of the liquid metal ink cartridge 2, G0 is the weight of the liquid metal ink cartridge 2 when it is empty, ρ is the density of the liquid metal, s is the bottom area of ​​the liquid metal ink cartridge 2, and g is the acceleration of gravity.

[0069] Next, the host computer of the ink supply system controls the ink supply pump 7 or the ink discharge pump 8 to work according to the value of the liquid level height h and the recommended liquid level height h0; when h-h0<-0.2mm, the liquid metal ink cartridge 2 is in an ink shortage state, and the host computer of the ink supply system starts the ink supply pump 7 to transport liquid metal to the liquid metal ink cartridge 2; when h-h0>0.2mm, the liquid metal ink cartridge 2 is in an ink overflow state, and the host computer of the ink supply system starts the ink discharge pump 8 to output liquid metal from the liquid metal ink cartridge 2; when -0.2mm≤h-h0≤0.2mm, the liquid metal ink cartridge 2 is in a normal working state, and the liquid level control component does not work.

[0070] It is worth noting that different liquid metal ink compositions have different recommended liquid level heights h0. The liquid level control component is to ensure that the liquid metal in the liquid metal ink cartridge is always at a suitable height for printing, so that the liquid metal's own gravity remains constant, which is conducive to the precise flow control of the ink supply system. If the liquid level control component is repeatedly started or continues to work for too long, it means that the liquid level in the liquid metal ink cartridge cannot reach the recommended height. Then the host computer of the ink supply system may determine that it has failed and prompt the user to check.

[0071] The air pressure control component is used to accurately adjust the pressure inside the liquid metal ink cartridge. Traditional printer ink supply systems do not have air pressure control components.

[0072] See also Figure 5 , a specific implementation manner shows an air pressure control component of a liquid metal ink supply system, including a negative pressure air pump 13, a positive pressure air pump 14, a pressure-stabilizing gas cylinder 15, a valve block 16, an air pressure control board 19, an air pipe 18 and a control circuit 21; the valve block 16 is connected to the liquid metal ink cartridge 2 of the ink supply system through the air pipe 18; the negative pressure air pump 13, the positive pressure air pump 14, and the pressure-stabilizing gas cylinder 15 are respectively connected to the valve block 16 through the air pipe 18; the air pressure control board 19 is connected to and controls the negative pressure air pump 13 and the positive pressure air pump 14 through the control circuit 21.

[0073] In the air pressure control assembly, the negative pressure air pump 13, the positive pressure air pump 14, and the pressure-stabilizing gas cylinder 15 are used to adjust the air pressure inside the liquid metal ink cartridge 2, and the valve block 16 plays a role in overall adjustment and control, and the control of each component is achieved through the control circuit 21.

[0074] The valve block 16 of the air pressure control assembly also includes an atmospheric communication port 22, an air pressure sensor 20, and an electromagnetic valve 17. The atmospheric communication port 22 connects the interior of the valve block 16 with the atmosphere; the air pressure sensor 20 is connected to the valve block 16 through an air pipe 18 to measure the air pressure of the valve block 16; the electromagnetic valve 17 is located inside the valve block 16, and is respectively arranged at the air pipe 18 connected to the liquid metal ink cartridge 2 and at the atmospheric communication port 22, by means of threaded connection.

[0075] It can be seen that the air pressure of the valve block 16 has a certain relationship with the air pressure of the liquid metal ink cartridge 2, which requires measurement by the air pressure sensor 20. The various parts of the air pressure control component are mainly connected and the air pressure is transported through the air pipe 18. There are two solenoid valves 17, both of which are connected to the inside of the valve block 16 for separate connection and separate control.

[0076] The connection between the air pressure control components is mainly completed by metal knurled joints 37, 38, 40, 42 and pagoda joints 39, 41. On the outside of the valve block 16, the connection with the air pipe 18 is threaded and sealed by metal knurled joints 37, 38, 40. The connection between the pressure-stabilizing gas cylinder 15 and the air pipe 18 is also threaded and sealed by metal knurled joints 42. Pagoda joints 39, 41 are respectively located on the negative pressure air pump 13, the positive pressure air pump 14, and the air pressure sensor 20, and are sealed at the connection with the air pipe 18. The selection of metal knurled joints or pagoda joints is based on ensuring the sealed connection of parts and components, and ensuring the premise of easy disassembly and maintenance. Different connectors should also be selected according to the different conveying and connecting materials, and the oxidation properties of the liquid metal itself and the related properties of the conveyed material should be fully considered.

[0077] The air pressure control assembly also includes a battery connected to the control circuit 21. This ensures that the air pressure control assembly is still effective when the device is powered off to prevent leakage of the print head.

[0078] The air pressure control method of the air pressure control component in the specific embodiment of the present invention mainly uses the host computer of the ink supply system to convert the air pressure to obtain the air pressure P in the liquid metal ink cartridge 2 for real-time control; the conversion formula is P = -(G-γ Cf) / s, where P is the air pressure, G is the weight of the liquid metal ink cartridge 2, γ is the simulation coefficient, C is the mass percentage of the oxide, f is the resistance in the ink supply system, and s is the bottom area of ​​the liquid metal ink cartridge 2. It can be seen that the value of the air pressure value P is related to the liquid level height h and the mass percentage C of the oxide in the liquid metal ink cartridge 2, and the various control components in the entire liquid metal ink supply system work together and are controlled together.

[0079] During the printing process, the host computer of the ink supply system controls the negative pressure air pump 13 or the positive pressure air pump 14 to work according to the printing requirements; when preparing to start printing, the host computer of the ink supply system starts the positive pressure air pump 14 to apply positive pressure to the liquid metal ink cartridge to give the liquid metal driving force. At this time, when G-γ Cf≤0, P≥0; when preparing to terminate printing, the host computer of the ink supply system starts the negative pressure air pump 13 to apply negative pressure to the liquid metal ink cartridge to give the liquid metal a balancing force. At this time, G-γ Cf>0, P<0.

[0080] It is worth noting that due to the weight of the liquid metal itself, when its liquid level reaches a certain height, its total weight is too heavy. At this time, even if no positive pressure is given and it is only connected to the atmosphere, the liquid metal will leak downwards. Therefore, the air pressure control component is required to give a negative pressure inside the liquid metal cartridge to balance the weight of the liquid metal and prevent leakage. This is the same principle as giving a negative pressure to the liquid metal cartridge when printing is about to stop, so that the liquid metal in the print head can be recovered and prevented from dripping. On the other hand, when the liquid metal level is lower than a certain value, although its weight is large, its surface tension is also large, so that it cannot enter the print head smoothly by its own weight. At this time, the air pressure control component is required to give it a positive pressure to push the liquid metal to flow downward and print.

[0081] The air pressure value range of the liquid metal ink cartridge 2 controlled by the air pressure control method during the printing process is -9kPa-9kPa.

[0082] The reduction ink path is the channel connecting the liquid metal ink cartridge and the print head. Its main function is to remove oxide impurities in the liquid metal, ensure that the liquid metal reaching the print head contains almost no oxides, prevent oxide particles from clogging the print head, and ensure printing quality.

[0083] See also Figure 7, a specific implementation manner shows a reduction ink path of a liquid metal ink supply system, including ink tubes 25, 28, 33, a reduction filter 24 and a print head 35; the ink tubes 25, 28, 33 connect the liquid metal ink cartridge 2 and the print head 35 to form an ink path; the reduction filter 24 is connected to the ink path and has a cavity, in which an oxide removal solution 30 is contained, so that the oxide in the liquid metal flowing through the reduction filter 24 to the print head 35 is reduced.

[0084] The reduction ink path also includes a one-way valve 23, which is connected to the ink path between the liquid metal ink cartridge 2 and the reduction filter 24, or directly connected to the inlet of the reduction filter 24. The function of the one-way valve is to prevent the liquid metal from flowing back. The above two methods can be set accordingly according to the length of the ink path, and there is no difference in function.

[0085] However, the location of the one-way valve 23 has a certain influence on the selection of the connectors between the one-way valve 23 and the reduction filter 24 and the ink tube. When the one-way valve 23 is connected between the liquid metal ink cartridge 2 and the reduction filter 24, both the one-way valve 23 and the reduction filter 24 have an inlet and an outlet. At this time, at the inlet and outlet of the one-way valve 23, Luer joints 26 and 27 are used to seal the ink tubes 25 and 28, while at the inlet and outlet of the reduction filter 24, pagoda joints 29 and 32 are used to seal the ink tubes 28 and 33. When the one-way valve 23 is directly connected to the inlet of the reduction filter 24, the one-way valve 23 has an inlet but no outlet, and the reduction filter 24 has an outlet but no inlet. At this time, the inlet of the one-way valve 23 is sealed with the ink tube 25 by a Luer joint, and the outlet of the reduction filter 24 is sealed with the ink tube 33 by a pagoda joint.

[0086] The connection between the print head 35 and the ink tube 33 of the ink path restoration is threadedly sealed by a knurled joint 34 .

[0087] In the above connection relationship, ink tubes 25, 28, 33, Luer connectors 26, 27, pagoda connectors 29, 32, and knurled connector 34 are all made of plastic. The characteristics of plastic connectors are that they are oxygen-impermeable and do not react with liquid metal to ensure the stability of the liquid metal.

[0088] The oxide removal solution 30 in the reduction filter 24 is one of NaOH, HCL, H2S04, and KOH solutions, with a volume not exceeding 40% of the cavity volume and a concentration of 0.05mol / L-0.5mol / L. Since the density of the oxide removal solution 30 is much lower than the density of the liquid metal, the oxide removal solution 30 is always on the upper surface of the reduced liquid metal 31 in the cavity, and the reduced liquid metal 31 sinks to the lower part of the cavity after reduction.

[0089] The above embodiments are only used to illustrate the present invention, but not to limit the present invention. Although the present invention is described in detail with reference to the embodiments, it should be understood by those skilled in the art that various combinations, modifications or equivalent substitutions of the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and should be included in the scope of the claims of the present invention.

Claims

1. A reduction ink circuit of a liquid metal ink supply system, characterized in that: It includes ink tubes (25, 28, 33), a reduction filter (24), a print head (35) and a one-way valve (23); The ink tube (25, 28, 33) connects the liquid metal ink cartridge (2) and the print head (35) to form an ink path; the reduction filter (24) is connected to the ink path and has a cavity, wherein the cavity contains an oxide removal solution (30) so that the oxide in the liquid metal flowing through the reduction filter (24) to the print head (35) is reduced; the one-way valve (23) is connected to the ink path between the liquid metal ink cartridge (2) and the reduction filter (24), and the one-way valve (23) is connected to the inlet of the reduction filter (24); The oxide removal solution (30) is one of NaOH, HCL, H2SO4, and KOH solutions, with a volume not exceeding 40% of the volume of the chamber and a concentration of 0.05 mol / L-0.5 mol / L; The invention also comprises: an air pressure control component, comprising: a negative pressure air pump (13), a positive pressure air pump (14), a pressure-stabilizing gas cylinder (15), a valve block (16), an air pressure control board (19), an air pipe (18) and a control circuit (21); the valve block (16) is connected to the liquid metal ink cartridge (2) of the liquid metal ink supply system through the air pipe (18); the negative pressure air pump (13), the positive pressure air pump (14) and the pressure-stabilizing gas cylinder (15) are respectively connected to the valve block (16) through the air pipe (18); the air pressure control board (19) is connected to the liquid metal ink cartridge (2) of the liquid metal ink supply system through the air pipe (18); The circuit (21) is connected to and controls the negative pressure air pump (13) and the positive pressure air pump (14); the valve block (16) also includes an atmospheric communication port (22) to connect the interior of the valve block (16) with the atmosphere; the air pressure control component also includes: an air pressure sensor (20) connected to the valve block (16) via an air pipe (18) to measure the air pressure of the valve block (16); and an electromagnetic valve (17) located inside the valve block (16) and connected to the air pipe (18) connected to the liquid metal ink cartridge (2). The metal knurled joints (37, 38, 40) are located outside the valve block (16) and are threadedly connected to the air pipe (18). The metal knurled joints (37, 38, 40) are used for threaded sealing connection at the connection with the air pipe (18). The connection between the pressure-stabilizing gas cylinder (15) and the air pipe (18) is also threadedly connected to the metal knurled joint (42). The pagoda joints (39, 41) are located on the negative pressure air pump (13), the positive pressure air pump (14), and the air pump (15), respectively. The connection between the pressure sensor (20) and the air pipe (18) is sealed; the battery is connected to the control circuit (21); the upper computer of the liquid metal ink supply system converts the air pressure to obtain the air pressure P in the liquid metal ink cartridge (2) for real-time control; the conversion formula is P=-(G-γC-f) / s, wherein P is the air pressure, G is the weight of the liquid metal ink cartridge (2), γ is the simulation coefficient, C is the mass percentage of the oxide, f is the resistance in the ink supply system, and s is the bottom area of ​​the liquid metal ink cartridge (2).

2. The restored ink path according to claim 1, characterized in that: The inlet and outlet of the one-way valve (23) are both sealedly connected to the ink tubes (25, 28) using Luer connectors (26, 27).

3. The reduction ink path according to claim 1 or 2, characterized in that: The inlet and outlet of the reduction filter (24) are both sealedly connected to the ink tubes (28, 33) using pagoda joints (29, 32).

4. The restored ink path according to claim 1, characterized in that: The connection between the print head (35) and the ink tube (33) is thread-sealed using a knurled joint (34).

5. The reduction ink path according to any one of claims 2 to 4, characterized in that: The ink tubes (25, 28, 33), the Luer connectors (26, 27), the pagoda connectors (29, 32), and the knurled connector (34) are all made of plastic.

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