A four-valve nozzle for a code jet

Abstract

The application discloses a four-valve nozzle for a code spraying machine, which comprises a nozzle shell, an insulating base plate detachably connected to the nozzle shell, and a nozzle upper cover rotatably connected to the top of the insulating base plate, wherein the nozzle upper cover and the insulating base plate cooperate to form a first upper cavity of the nozzle, a valve seat is fixed on one side of the first upper cavity of the nozzle in the nozzle shell, a second upper cavity of the nozzle is formed above the valve seat, and a lower cavity of the nozzle is formed below the first upper cavity and the second upper cavity of the nozzle; a spraying cavity, a charging detection pole assembly and a high-voltage deflection pole plate assembly are arranged on the insulating base plate, and a recovery groove is arranged on the nozzle shell; an ink electromagnetic valve, a backflow electromagnetic valve, a cleaning electromagnetic valve and a recovery electromagnetic valve are arranged on the upper surface of the valve seat, and a valve passage plate connected to the ink electromagnetic valve, the backflow electromagnetic valve, the cleaning electromagnetic valve and the recovery electromagnetic valve is arranged on the lower surface of the valve seat. The nozzle has the advantages that the spraying and printing elements in the first upper cavity of the nozzle can be conveniently cleaned, there is no problem of damage of high-voltage wires, the maintenance and replacement cost of the insulating base plate is low, and the nozzle of the spraying cavity is convenient to disassemble and clean.

Description

Technical Field

[0001] This invention belongs to the field of inkjet printer technology, and specifically relates to a four-valve printhead for inkjet printers. Background Technology

[0002] As a mature printing equipment, inkjet printers are widely used in various fields such as food, beverage, electronics, pharmaceuticals, and building materials to print production dates, batch numbers, barcodes, QR codes, and other identification information on the surface of products or packaging.

[0003] The printhead is the core component of an inkjet printer. Internally, it typically contains a print chamber, charging electrodes, detection electrodes, a high-voltage deflection plate assembly, a recycling tank, and other printing components. The high-voltage deflection plate assembly includes two high-voltage deflection plates, one applying a positive voltage and the other a negative voltage, to create a deflection electric field. A crystal oscillator is located inside the print chamber, and nozzles are positioned outside the print chamber. During operation, ink entering the print chamber is ejected from the nozzles as intermittent droplets under the high-frequency vibration of the crystal oscillator. These droplets travel forward along their ejection path. Some droplets are charged by the charging electrodes as they pass through the charging area, acquiring a negative charge proportional to the applied voltage. These charged droplets continue flying, and when they pass between the two high-voltage deflection plates, their flight path is deflected by the electric field. The ink droplets eventually land on the surface of the object to be printed, forming the desired mark. The remaining ink droplets are not charged by the charging electrode when they fly through the charging area formed by the charging electrode, thus becoming uncharged ink droplets. These uncharged ink droplets return to the ink tank of the inkjet printer via the recycling tank after flying through the area between the two high-voltage deflection plates, realizing the recycling of ink. When the inkjet printer is not printing a mark, the charging electrode pre-charges the ink droplets ejected from the nozzle of the printing chamber with a low voltage to establish an initial charge state. The detection electrode detects the pre-charged ink droplets for phase detection and adjusts the charging timing of subsequent ink droplets based on the detection results. Subsequently, according to the printing requirements, the charging electrode applies a variable charging voltage corresponding to the desired deflection position to the phase-adjusted ink droplets that are to be printed, so that they carry the corresponding negative charge.

[0004] However, existing nozzle structures still have the following shortcomings in practical applications:

[0005] First, current printheads are usually covered by detachable covers to protect the internal printing components. When it is necessary to clean or maintain the printing components inside the printhead, the cover must be removed from the printhead housing, which is a cumbersome operation and makes cleaning and maintenance inconvenient.

[0006] Secondly, some nozzles have the high-voltage deflection plates directly mounted on the cover plate. This arrangement requires the laying of high-voltage wires that are electrically connected to the high-voltage deflection plates on the cover plate. Since the cover plate needs to be opened and closed frequently during cleaning, maintenance and daily use, the high-voltage wires are frequently bent and pulled. After long-term use, the insulation layer is prone to wear and conductor breakage, which not only affects the reliability of power supply, but also poses certain safety hazards.

[0007] Third, the printing components inside the printhead, such as the spray chamber, charging electrode, and high-voltage deflection plate assembly, are usually mounted on the printhead's insulating substrate. Currently, the insulating substrate is generally integrally connected to the printhead housing. Under the long-term application of high voltage by the high-voltage deflection plates, the insulation performance of the area between the two high-voltage deflection plates on the insulating substrate is prone to decline due to electrolytic corrosion, aging, and other reasons. Once the insulation performance declines, it will directly affect the reliability and printing accuracy of the printhead. In this case, to restore the equipment performance, the insulating substrate needs to be replaced. However, since the insulating substrate and the printhead housing are an integral structure, the printhead housing must be replaced together when replacing the insulating substrate, resulting in high maintenance and replacement costs.

[0008] Fourth, the charging electrode and the detection electrode of the existing printhead are fixedly mounted on the insulating substrate as two independent printing components. When disassembling and cleaning the nozzle of the spray chamber, the charging electrode and the detection electrode will cause spatial interference to the disassembly of the nozzle, making it inconvenient to disassemble and clean the nozzle.

[0009] Fifth, existing printheads can generally only be connected and installed in a fixed direction to the inkjet printer's chassis. This limitation on installation direction makes it difficult to adapt to different production line layouts, different installation spaces, and different printing angle requirements, causing inconvenience for users' on-site installation and debugging, and also limiting the applicability and flexibility of the inkjet printer under different working conditions. Summary of the Invention

[0010] In view of the above-mentioned defects of the prior art, the present invention provides a four-valve printhead for inkjet printers, which facilitates cleaning and maintenance of the printing components in the first upper cavity of the printhead, eliminates the problem of high-voltage wire damage, reduces the cost of repair and replacement after the insulation performance of the insulating substrate deteriorates, and makes the nozzle of the printing cavity easy to disassemble and clean.

[0011] The technical solution adopted by this invention to solve its technical problem is:

[0012] A four-valve printhead for an inkjet printer includes a printhead housing, an insulating substrate detachably connected to the printhead housing, and a printhead flip cover rotatably connected above the insulating substrate. The printhead flip cover and the insulating substrate cooperate to form a first upper cavity of the printhead. A valve seat is fixed inside the printhead housing on one side of the first upper cavity. A second upper cavity is formed in the area above the valve seat, and a lower cavity is formed in the area below the first and second upper cavities. A spray cavity, a charging detection electrode assembly, and a high-voltage deflection electrode assembly are sequentially arranged along the spray path on the upper surface of the insulating substrate. A recovery groove is provided on the printhead housing downstream of the high-voltage deflection electrode assembly. A high-voltage wire electrically connected to the high-voltage deflection electrode assembly is arranged in the lower cavity of the printhead. The charging detection electrode seat of the charging detection electrode assembly is detachably connected to the insulating substrate. An ink solenoid valve, a return solenoid valve, a cleaning solenoid valve, and a recovery solenoid valve are sequentially arranged on the upper surface of the valve seat. A valve channel plate connected to the ink solenoid valve, the return solenoid valve, the cleaning solenoid valve, and the recovery solenoid valve is provided on the lower surface of the valve seat.

[0013] Furthermore, one end of the valve channel plate is sequentially connected to an ink pipe connector, a return pipe connector, an internal cleaning pipe connector, and a recovery pipe connector, while the other end is sequentially connected to a spray chamber inlet pipe connector, a spray chamber outlet pipe connector, and a recovery tank connection pipe connector.

[0014] The ink pipe connector is connected to the ink tank inside the printer's chassis via an ink pipe equipped with an ink pressurizing pump; the return pipe connector is connected to one end of a return pipe equipped with a return suction pump, and the other end of the return pipe is connected to both the ink tank and the liquid storage tank inside the chassis via a return three-way valve; the internal cleaning pipe connector is connected to the cleaning liquid tank inside the chassis via an internal cleaning pipe equipped with a first cleaning liquid pressurizing pump; and the recovery pipe connector is connected to the ink tank via a recovery pipe.

[0015] The ink pipe connector is connected to the ink solenoid valve in sequence via a valve channel plate and a valve seat. The ink solenoid valve is connected to the spray chamber inlet pipe connector in sequence via a valve seat and a valve channel plate. The return pipe connector is connected to the return solenoid valve in sequence via a valve channel plate and a valve seat. The return solenoid valve is connected to the spray chamber outlet pipe connector in sequence via a valve seat and a valve channel plate. The internal cleaning pipe connector is connected to the cleaning solenoid valve in sequence via a valve channel plate and a valve seat. The cleaning solenoid valve is connected to the spray chamber inlet pipe connector in sequence via a valve seat and a valve channel plate. The recovery pipe connector is connected to the recovery solenoid valve in sequence via a valve channel plate and a valve seat. The recovery solenoid valve is connected to the recovery tank connection pipe connector in sequence via a valve seat and a valve channel plate.

[0016] The spray chamber inlet pipe connector is connected to the inlet of the spray chamber through the spray chamber inlet pipe, the spray chamber outlet pipe connector is connected to the outlet of the spray chamber through the spray chamber outlet pipe, and the recovery tank connection pipe connector is connected to the recovery tank through the recovery tank connection pipe.

[0017] The four-valve printhead performs the printing operation. The ink solenoid valve, the return solenoid valve, and the recovery solenoid valve work together. The inlet pipe of the spray chamber is connected to the ink solenoid valve in sequence through the valve channel plate and the valve seat. The other end of the return pipe is connected to the ink tank.

[0018] The four-valve nozzle performs internal cleaning of the spray chamber. The cleaning solenoid valve and the return solenoid valve work together. The inlet pipe of the spray chamber is connected to the cleaning solenoid valve in sequence through the valve channel plate and the valve seat. The other end of the return pipe is connected to the liquid storage tank.

[0019] Furthermore, the nozzle housing has an opening at one end corresponding to the positions of the second upper cavity and the lower cavity of the nozzle, forming a throat connection port. The nozzle housing is detachably connected to a throat connector at the throat connection port. The throat connector includes a throat connector frame, and a throat connector tube is integrally formed on the outer end of the throat connector frame. The axis of the throat connector tube is not parallel to the center line of the frame opening of the throat connector frame. The inner end of the throat connector frame is detachably and sealingly connected to the nozzle housing at the throat connection port. The free end of the throat connector tube is connected to the chassis through the throat tube. The throat connector can rotate 180° around a rotation axis perpendicular to the plane where the throat connection port is located, allowing the axis of the throat connector tube to switch between a first direction and a second direction.

[0020] Furthermore, the spray cavity inlet pipe, spray cavity outlet pipe, and recovery tank connecting pipe are all arranged inside the lower cavity of the printhead. The insulating substrate has spray cavity connection ports at positions corresponding to the spray cavity inlet and the spray cavity outlet, respectively. One end of the spray cavity inlet pipe is connected to the spray cavity inlet through one of the insulating substrate spray cavity connection ports, and one end of the spray cavity outlet pipe is connected to the spray cavity outlet through the other insulating substrate spray cavity connection port. The ink pipe, return pipe, internal cleaning pipe, and recovery pipe all pass through the lower cavity of the printhead and the throat pipe in sequence.

[0021] Furthermore, the charging detection electrode holder is detachably connected to the substrate holder fixed to the upper surface of the insulating substrate by bolts; the charging detection electrode assembly includes a charging electrode and a detection electrode sequentially mounted on the charging detection electrode holder along the spray path;

[0022] The charging electrode and the detection electrode are respectively electrically connected to the electronic amplifier block arranged in the lower cavity of the nozzle through a common wire that passes through the inner cavity of the charging and detection electrode base and the insulating substrate in sequence; or the charging electrode and the detection electrode are both electrically connected to the electronic amplifier block through a spring-loaded connector that passes through the inner cavity of the charging and detection electrode base and the insulating substrate in sequence.

[0023] The electronic amplifier is electrically connected to the control circuit located inside the chassis via ordinary wires passing through the throat tube.

[0024] Furthermore, an electronic amplification block placement cavity is provided around the outer side of the electronic amplification block on the lower surface of the insulating substrate, which is located within the lower cavity of the nozzle. The electronic amplification block is located within the electronic amplification block placement cavity, and the electronic amplification block placement cavity is filled with insulating adhesive around the electronic amplification block.

[0025] Two high-voltage electrode seats are also provided on the upper surface of the insulating substrate. Each high-voltage electrode seat is provided with a high-voltage deflection plate conductive element. Each high-voltage deflection plate of the high-voltage deflection plate assembly is installed on the corresponding high-voltage electrode seat and is electrically connected to the control circuit in the chassis through the corresponding high-voltage deflection plate conductive element and the high-voltage wire that passes through the nozzle lower cavity and the throat tube in sequence. An isolation cavity is provided on the lower surface of the insulating substrate at a position corresponding to each high-voltage deflection plate conductive element in the nozzle lower cavity. The end of the high-voltage wire connected to the high-voltage deflection plate conductive element is called the high-voltage wire conductive element connection end. The part of the high-voltage wire near the high-voltage wire conductive element connection end is in the corresponding isolation cavity, and the isolation cavity is filled with insulating glue around the high-voltage wire.

[0026] The portion of the high-voltage conductor located inside the lower cavity of the nozzle and the recovery tank connecting pipe are both arranged outside the electronic amplifier block placement cavity.

[0027] Furthermore, an external cleaning nozzle is provided on one side of the spray path on the upper surface of the insulating substrate. The external cleaning nozzle is connected to the cleaning fluid tank through an external cleaning pipe that passes through the lower cavity of the printhead and the throat in sequence and is equipped with a second cleaning fluid pressurization pump. The cleaning fluid tank is connected to the inner cleaning pipe and the outer cleaning pipe through a cleaning three-way valve. The cleaning fluid sprayed through the external cleaning nozzle is used to clean the residual ink droplets in the first upper cavity of the printhead.

[0028] Furthermore, the external cleaning nozzle is provided with three sets of spray nozzles. The spray direction of the first set of spray nozzles is aligned with the nozzle of the spray chamber, the spray direction of the second set of spray nozzles is aligned with the charging electrode, and the spray direction of the third set of spray nozzles is aligned with the high-voltage deflection plate assembly.

[0029] Furthermore, a crystal oscillator conductive element is disposed on the insulating substrate, and the crystal oscillator in the spray cavity is electrically connected to the control circuit in the chassis through the crystal oscillator conductive element and ordinary wires that pass through the lower cavity of the nozzle and the throat tube in sequence.

[0030] Furthermore, an observation port is provided on the flip cover of the printhead at a position corresponding to the nozzle of the spray chamber, and a magnifying glass is installed at the observation port for observing the separation state of the ink droplets ejected from the nozzle of the spray chamber; the printhead housing is detachably and sealingly connected to the lower cover of the printhead at the lower end opening of the lower cavity of the printhead, and the printhead housing is slidably connected to the upper cover of the printhead at the upper end opening of the second upper cavity of the printhead.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] This invention relates to a four-valve printhead for an inkjet printer, comprising a printhead housing, an insulating substrate detachably connected to the printhead housing, and a printhead flip-top rotatably connected above the insulating substrate. The printhead flip-top and the insulating substrate cooperate to form a first upper cavity of the printhead. A valve seat is fixed inside the printhead housing on one side of the first upper cavity. A second upper cavity is formed in the area above the valve seat within the printhead housing, and a lower cavity is formed in the area below the first and second upper cavities. A spray cavity, a charging detection electrode assembly, and a high-voltage deflection electrode assembly are sequentially arranged along the spray path on the upper surface of the insulating substrate. A recovery groove is provided on the printhead housing downstream of the high-voltage deflection electrode assembly. A high-voltage wire electrically connected to the high-voltage deflection electrode assembly is arranged in the lower cavity of the printhead. The charging detection electrode seat of the charging detection electrode assembly is detachably connected to the insulating substrate. An ink solenoid valve, a return solenoid valve, a cleaning solenoid valve, and a recovery solenoid valve are sequentially arranged on the upper surface of the valve seat. A valve channel plate connected to all three solenoid valves is provided on the lower surface of the valve seat. Because the printhead cover is rotatably connected to the printhead housing, when cleaning or maintaining the printing components inside the first upper cavity of the printhead is required, simply flip the printhead cover upwards to open it and expose the printing components inside the first upper cavity. This simple operation facilitates cleaning and maintenance of the printing components inside the first upper cavity. Furthermore, since the high-voltage wires electrically connected to the high-voltage deflection plate assembly are located inside the lower cavity of the printhead, the high-voltage wires are not frequently bent or pulled when opening and closing the printhead cover. This eliminates the insulation wear and conductor breakage problems associated with high-voltage wires mentioned in the prior art, thus ensuring the reliability of the high-voltage deflection plate assembly's power supply and eliminating any safety concerns. The advantages of this design are: Firstly, because the insulating substrate and nozzle housing are detachably and sealed, if the insulation performance of the area between the two high-voltage deflection plates of the high-voltage deflection plate assembly on the insulating substrate deteriorates due to electrolytic corrosion, aging, or other reasons, the insulating substrate can be replaced directly without replacing the nozzle housing as well. Therefore, the repair and replacement cost of the insulating substrate after its insulation performance deteriorates is low. Secondly, because the charging detection electrode assembly's charging detection electrode holder is detachably connected to the insulating substrate, when it is necessary to disassemble the nozzle of the cleaning spray chamber, the charging detection electrode holder of the charging detection electrode assembly can be directly removed from the insulating substrate. This prevents the charging electrode and detection electrode of the charging detection electrode assembly from interfering with the disassembly of the nozzle, thus facilitating the disassembly of the nozzle of the cleaning spray chamber. Attached Figure Description

[0033] Figure 1 This is a three-dimensional structural diagram of the four-valve printhead of the inkjet printer of the present invention, in which the charging electrode and the detection electrode are electrically connected to the electronic amplifier block through ordinary wires, and the axis of the throat connecting tube is parallel to the direction of the spray path of the printhead.

[0034] Figure 2 for Figure 1 A partially enlarged structural diagram;

[0035] Figure 3 for Figure 1 A three-dimensional structural diagram of the concealed nozzle after the sliding cover is removed;

[0036] Figure 4 for Figure 1 A schematic diagram of the three-dimensional structure from another direction;

[0037] Figure 5 for Figure 4 A schematic diagram of the three-dimensional structure behind the concealed nozzle cover;

[0038] Figure 6 This is a three-dimensional structural diagram of the four-valve printhead of the inkjet printer of the present invention, in which the charging electrode and the detection electrode are electrically connected to the electronic amplifier block through ordinary wires, and the axis of the throat connecting tube is perpendicular to the direction of the spray path of the printhead.

[0039] Figure 7 This is a three-dimensional structural diagram of the four-valve printhead of the inkjet printer of the present invention, in which the charging electrode and the detection electrode are electrically connected to the electronic amplifier block through a spring pin connector, and the axis of the throat connecting tube is parallel to the direction of the printhead's spray path.

[0040] Figure 8 for Figure 7 A partially enlarged sectional view;

[0041] Figure 9 This is a three-dimensional structural diagram of the four-valve printhead of the inkjet printer of the present invention, in which the charging electrode and the detection electrode are electrically connected to the electronic amplifier block through a spring pin connector, and the axis of the throat connecting tube is perpendicular to the direction of the printhead's spray path.

[0042] Figure 10 This is a three-dimensional structural diagram of the nozzle housing from one direction.

[0043] Figure 11 This is a three-dimensional structural diagram of the nozzle housing from another direction;

[0044] Figure 12 This is a three-dimensional structural diagram of the insulating substrate in one direction when the charging electrode and the detection electrode in the four-valve printhead of the inkjet printer of the present invention are electrically connected to the electronic amplifier block through ordinary wires.

[0045] Figure 13 for Figure 12 A schematic diagram of the three-dimensional structure from another direction;

[0046] Figure 14This is a three-dimensional structural diagram of the insulating substrate when both the charging electrode and the detection electrode in the four-valve printhead of the inkjet printer of the present invention are electrically connected to the electronic amplifier block through a spring-loaded connector.

[0047] Figure 15 This is a three-dimensional structural diagram of the valve channel plate in one direction.

[0048] Figure 16 This is a three-dimensional structural diagram of the valve channel plate from another direction.

[0049] Figure reference numerals: 1. Printhead housing; 101. Throat connection port; 2. Insulating substrate; 3. Printhead flip cover; 301. Observation port; 302. Ink droplet exit port; 4. Valve seat; 5. Second upper chamber of printhead; 6. Lower chamber of printhead; 7. Spray chamber; 801. Charging detection electrode; 802. Charging electrode; 803. Detection electrode; 804. Spring connector; 9. Recovery tank; 10. Ink solenoid valve; 11. Return solenoid valve; 12. Cleaning solenoid valve; 13. Recovery solenoid valve; 14. Valve channel plate; 15. Ink tube connector; 16. 17. Return pipe connector, 18. Internal cleaning pipe connector, 19. Recovery pipe connector, 20. Spray chamber inlet pipe connector, 21. Spray chamber outlet pipe connector, 22. Recovery tank connecting pipe connector, 23. Throat connector, 24. Throat connector frame, 25. Throat connecting pipe, 26. Electronic amplifier block placement cavity, 27. External cleaning nozzle, 28. High-voltage electrode base, 29. High-voltage deflection electrode plate, 20. Nozzle lower cover, 21. Nozzle upper sliding cover, 22. Spray chamber nozzle, 23. Isolation cavity, 34. Valve channel plate cover, 35. Base plate base. Detailed Implementation

[0050] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0051] In the description of this invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0052] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0053] like Figures 1-11 As shown, a four-valve printhead for an inkjet printer includes a printhead housing 1, an insulating substrate 2 detachably connected to the printhead housing 1, and a printhead flip-up cover 3 rotatably connected above the insulating substrate 2. The printhead flip-up cover 3 and the insulating substrate 2 cooperate to form a first upper cavity of the printhead. A valve seat 4 is fixed inside the printhead housing 1 on one side of the first upper cavity of the printhead. A second upper cavity 5 of the printhead is formed in the area above the valve seat 4 inside the printhead housing 1, and a lower cavity 6 of the printhead is formed in the area below the first upper cavity and the second upper cavity 5 of the printhead. A spray chamber 7 and a charging detection electrode group are sequentially arranged along the spray path on the upper surface of the insulating substrate 2. The nozzle housing 1 has a high-voltage deflection plate assembly and a recovery trough 9 on the downstream side of the high-voltage deflection plate assembly. A high-voltage wire electrically connected to the high-voltage deflection plate assembly is arranged in the lower cavity 6 of the nozzle. The charging detection electrode seat 801 of the charging detection electrode assembly is detachably connected to the insulating substrate 2. An ink solenoid valve 10, a return solenoid valve 11, a cleaning solenoid valve 12, and a recovery solenoid valve 13 are arranged sequentially on the upper surface of the valve seat 4. A valve channel plate 14 is arranged on the lower surface of the valve seat 4, which is connected to the ink solenoid valve 10, the return solenoid valve 11, the cleaning solenoid valve 12, and the recovery solenoid valve 13.

[0054] Since the printhead cover 3 is rotatably connected to the printhead housing 1, when it is necessary to clean or maintain the printing components in the first upper cavity of the printhead, it is only necessary to flip the printhead cover 3 upwards to open it and expose the printing components in the first upper cavity of the printhead to the outside. The operation of opening the printhead cover 3 is simple, thus facilitating the cleaning and maintenance of the printing components in the first upper cavity of the printhead. Since the high-voltage wires electrically connected to the high-voltage deflection plate assembly are arranged in the lower cavity 6 of the printhead, the high-voltage wires will not be frequently bent or pulled when opening and closing the printhead cover 3. There are no problems such as insulation wear and conductor breakage of high-voltage wires as seen in the background art. Therefore, it will not affect the power supply reliability of the high-voltage deflection plate assembly and there is no safety hazard. Since the insulating substrate 2 and The nozzle housing 1 is detachably sealed, so when the insulation performance of the part of the insulating substrate 2 between the two high-voltage deflection plates 2502 of the high-voltage deflection plate assembly decreases due to electrolytic corrosion, aging, etc., the insulating substrate 2 can be replaced directly without replacing the nozzle housing 1. Therefore, the maintenance and replacement cost of the insulating substrate 2 after the insulation performance decreases is low. Since the charging detection electrode seat 801 of the charging detection electrode assembly is detachably connected to the insulating substrate 2, when it is necessary to disassemble the nozzle of the cleaning spray chamber 7, the charging detection electrode seat 801 of the charging detection electrode assembly can be directly removed from the insulating substrate 2 to prevent the charging electrode 802 and the detection electrode 803 of the charging detection electrode assembly from causing spatial position interference to the disassembly of the nozzle. Therefore, it is convenient to disassemble the nozzle of the cleaning spray chamber 7.

[0055] Among them, such as Figure 5 , Figure 15 and Figure 16 As shown, one end of the valve channel plate 14 is sequentially connected to the ink pipe connector 15, the return pipe connector 16, the internal cleaning pipe connector 17, and the recovery pipe connector 18, while the other end is sequentially connected to the spray chamber inlet pipe connector 19, the spray chamber outlet pipe connector 20, and the recovery tank connection pipe connector 21. The valve channel plate 14 has a detachable and sealingly connected valve channel plate cover plate 30 on the side opposite to the valve seat 4.

[0056] Ink pipe connector 15 is connected to the ink tank inside the printer chassis via an ink pipe with an ink pressurizing pump; return pipe connector 16 is connected to one end of a return pipe with a return suction pump, and the other end of the return pipe is connected to the ink tank and the liquid storage tank inside the chassis via a return three-way valve; internal cleaning pipe connector 17 is connected to the cleaning liquid tank inside the chassis via an internal cleaning pipe with a first cleaning liquid pressurizing pump; recovery pipe connector 18 is connected to the ink tank via a recovery pipe.

[0057] Ink pipe connector 15 is connected to ink solenoid valve 10 via valve channel plate 14 and valve seat 4 in sequence. Ink solenoid valve 10 is connected to spray chamber inlet pipe connector 19 via valve seat 4 and valve channel plate 14 in sequence. Return pipe connector 16 is connected to return solenoid valve 11 via valve channel plate 14 and valve seat 4 in sequence. Return solenoid valve 11 is connected to spray chamber outlet pipe connector 20 via valve seat 4 and valve channel plate 14 in sequence. Internal cleaning pipe connector 17 is connected to cleaning solenoid valve 12 via valve channel plate 14 and valve seat 4 in sequence. Cleaning solenoid valve 12 is connected to spray chamber inlet pipe connector 19 via valve seat 4 and valve channel plate 14 in sequence. Recovery pipe connector 18 is connected to recovery solenoid valve 13 via valve channel plate 14 and valve seat 4 in sequence. Recovery solenoid valve 13 is connected to recovery tank connection pipe connector 21 via valve seat 4 and valve channel plate 14 in sequence.

[0058] The spray chamber inlet pipe joint 19 is connected to the inlet of the spray chamber 7 through the spray chamber inlet pipe, the spray chamber outlet pipe joint 20 is connected to the outlet of the spray chamber 7 through the spray chamber outlet pipe, and the recovery tank connection pipe joint 21 is connected to the recovery tank 9 through the recovery tank connection pipe.

[0059] The four-valve printhead performs the printing work. The ink solenoid valve 10, the return solenoid valve 11 and the recovery solenoid valve 13 work together. The inlet pipe connector 19 of the spray chamber is connected to the ink solenoid valve 10 through the valve channel plate 14 and the valve seat 4 in sequence. The other end of the return pipe is connected to the ink tank.

[0060] The four-valve nozzle performs internal cleaning of the spray chamber 7. The cleaning solenoid valve 12 and the return solenoid valve 11 work together. The inlet pipe joint 19 of the spray chamber is connected to the cleaning solenoid valve 12 through the valve channel plate 14 and the valve seat 4 in sequence. The other end of the return pipe is connected to the liquid storage tank.

[0061] When the four-valve printhead performs printing, the ink solenoid valve 10 and the recovery solenoid valve 13 are opened simultaneously. The ink in the ink tank, under the pressure of the ink pressurizing pump, sequentially passes through the ink tube, ink tube connector 15, valve channel plate 14, valve seat 4, ink solenoid valve 10, valve seat 4, valve channel plate 14, nozzle inlet connector 19, nozzle inlet pipe, and the inlet of nozzle 7, entering the nozzle 7. The ink entering the nozzle 7 is then ejected from the nozzle outside the nozzle 7 as intermittent droplets under the high-frequency vibration of the crystal oscillator within the nozzle 7. The droplets travel forward along the ejection path, and some droplets are charged by the charging electrode 8 when they pass through the charging area formed by the charging electrode 8, carrying a negative charge proportional to the voltage applied by the charging electrode 8. The ink droplets continue to fly. When they pass through the area between the two high-voltage deflection plates 2502 of the high-voltage deflection plate assembly, their flight path is deflected under the action of the electric field force. Finally, they fly out of the first upper cavity of the printhead and fall onto the surface of the object to be printed, forming the required mark. The remaining ink droplets are not charged by the charging electrode 8 when they fly through the charging area formed by the charging electrode 8, and thus become uncharged ink droplets. After passing through the area between the two high-voltage deflection plates 2502, these uncharged ink droplets pass through the recovery tank 9, the recovery tank connecting pipe, the recovery tank connecting pipe joint 21, the valve channel plate 14, the valve seat 4, the recovery solenoid valve 13, the valve seat 4, the valve channel plate 14, the recovery pipe joint 18, and the recovery pipe in sequence to return to the ink tank, realizing the recycling of ink.

[0062] During the printing process of the four-valve printhead, when it is necessary to stir the ink in the spray chamber 7, the reflux solenoid valve 11 is opened, and the other end of the reflux pipe is connected to the ink tank by controlling the reflux three-way valve. In this way, part of the ink entering the spray chamber 7 is drawn back into the ink tank by the reflux suction pump through the outlet of the spray chamber 7, the spray chamber outlet pipe, the spray chamber outlet pipe connector 20, the valve channel plate 14, the valve seat 4, the reflux solenoid valve 11, the valve seat 4, the valve channel plate 14, the reflux pipe connector 16, and the reflux pipe, thereby achieving the stirring of the ink in the spray chamber 7.

[0063] When the four-valve printhead performs the internal cleaning operation of the spray chamber 7, the cleaning solenoid valve 12 and the return solenoid valve 11 are opened simultaneously. The other end of the return pipe is connected to the storage tank by controlling the return three-way valve. In this way, the cleaning liquid in the cleaning liquid tank, under the pressure of the first cleaning liquid pressurizing pump, enters the spray chamber 7 through the inner cleaning pipe, the inner cleaning pipe connector 17, the valve channel plate 14, the valve seat 4, the cleaning solenoid valve 12, the valve seat 4, the valve channel plate 14, the spray chamber inlet pipe connector 19, the spray chamber inlet pipe and the inlet of the spray chamber 7 in sequence, thereby cleaning the ink in the spray chamber 7. The diluted liquid formed in the spray chamber 7 after cleaning then flows back to the storage tank through the outlet of the spray chamber 7, the spray chamber outlet pipe, the spray chamber outlet pipe connector 20, the valve channel plate 14, the valve seat 4, the return solenoid valve 11, the valve seat 4, the valve channel plate 14, the return pipe connector 16 and the return pipe in sequence.

[0064] When the inkjet printer is turned off or the ink line is not turned on for a long time, the recovery tube needs to be closed by the recovery solenoid valve 13 to prevent the recovery tube from communicating with the outside air and reduce the blockage caused by ink drying in the recovery tube.

[0065] In this process, ink dots with different amounts of negative charge are deflected by different distances under the action of the two high-voltage deflection plates 2502 of the high-voltage deflection plate assembly, so as to print the required markings on the moving object to be printed.

[0066] Among them, the printhead flip cover 3 has an ink droplet exit 302 on the downstream side of the high-voltage deflection plate assembly. The ink droplets whose flight path is deflected fly out of the first upper cavity of the printhead from the ink droplet exit 302 and fall onto the surface of the object to be printed.

[0067] The nozzle outside the spray chamber 7 is called the spray chamber nozzle 28.

[0068] in, Figure 2 , Figure 6 and Figure 8 The direction indicated by the middle arrow A is the direction of the jet path.

[0069] In one embodiment, such as Figure 10 and Figure 11 As shown, the nozzle housing 1 has an opening at one end corresponding to the positions of the second upper cavity 5 and the lower cavity 6 of the nozzle, forming a throat connection port 101, as shown. Figure 1 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 9 As shown, the nozzle housing 1 is detachably connected to the throat connector 22 at the throat connection port 101. The throat connector 22 includes a throat connector frame 2201. The outer end of the throat connector frame 2201 is integrally provided with a throat connection tube 2202. The axis of the throat connection tube 2202 is not parallel to the center line of the frame opening of the throat connector frame 2201. The inner end of the throat connector frame 2201 is detachably and sealed to the nozzle housing 1 at the throat connection port 101. The free end of the throat connection tube 2202 is connected to the chassis through the throat tube. The throat connector 22 can rotate 180° around a rotation axis perpendicular to the plane where the throat connection port 101 is located, so that the axis of the throat connection tube 2202 switches between the first direction and the second direction.

[0070] By controlling the throat connector 22 to rotate 180° around the rotation axis perpendicular to the plane where the throat connector 101 is located, and by detachably and sealingly connecting the throat connector frame 2201 to the throat connector 101 on the printhead housing 1, the axis of the throat connector 2202 can be switched from the first direction to the second direction. Therefore, this four-valve printhead can be connected and installed to the inkjet printer chassis along the first direction and the second direction respectively. The installation direction is not restricted, and it can adapt to different production line layouts, different installation spaces and different printing angle requirements, which is convenient for users to install and debug on site. At the same time, it can improve the applicability and flexibility of the inkjet printer under different working conditions.

[0071] The direction of the straight line perpendicular to the plane of the throat connection port 101 is called the vertical direction of the throat connection port. The vertical direction of the throat connection port is inclined relative to the direction of the nozzle's spray path, so that the axis of the throat connection pipe 2202 is parallel to the direction of the nozzle's spray path in the first direction, and the axis of the throat connection pipe 2202 is perpendicular to the direction of the nozzle's spray path in the second direction.

[0072] The spray cavity inlet pipe, spray cavity outlet pipe, and recovery tank connecting pipe are all arranged in the lower cavity 6 of the printhead. The insulating substrate 2 has an insulating substrate spray cavity connection port at the position corresponding to the inlet and outlet of the spray cavity 7, respectively. A sealing ring is provided at the two insulating substrate spray cavity connection ports. One end of the spray cavity inlet pipe is connected to the inlet of the spray cavity 7 through one of the insulating substrate spray cavity connection ports, and one end of the spray cavity outlet pipe is connected to the outlet of the spray cavity 7 through the other insulating substrate spray cavity connection port. The ink tube, return tube, internal cleaning tube, and recovery tube all pass through the lower cavity 6 of the printhead and the throat tube in sequence.

[0073] This design of the lower cavity 6 of the printhead facilitates the arrangement of the spray cavity inlet pipe, spray cavity outlet pipe, recovery tank connecting pipe, ink pipe, return pipe, internal cleaning pipe, and recovery pipe within the lower cavity 6 of the printhead.

[0074] The charging detection electrode 801 is detachably connected to the substrate base 31 fixed to the upper surface of the insulating substrate 2 by bolts. Figure 8 The charging detection electrode assembly includes a charging electrode 802 and a detection electrode 803 sequentially mounted on the charging detection electrode holder 801 along the injection path, see... Figures 1-3 as well as Figures 6-9 ;

[0075] The charging electrode 802 and the detection electrode 803 are respectively electrically connected to the electronic amplifier block arranged in the lower cavity 6 of the nozzle via a common wire that passes sequentially through the inner cavity of the charging and detection electrode holder 801 and the insulating substrate 2; or the charging electrode 802 and the detection electrode 803 are both electrically connected to the electronic amplifier block via a spring-loaded connector 804 that passes sequentially through the inner cavity of the charging and detection electrode holder 801 and the insulating substrate 2, see Figure 8 ;

[0076] The electronic amplifier is electrically connected to the control circuit located inside the chassis via ordinary wires passing through the lower cavity 6 of the nozzle and the throat.

[0077] By sequentially mounting the charging electrode 802 and the detection electrode 803 onto the charging and detection electrode holder 801, the charging electrode 802 and the detection electrode 803 are integrated into a single printing component. This allows for simultaneous separation of the charging electrode 802 and the detection electrode 803 from the insulating substrate 2 simply by removing the charging and detection electrode holder 801 from the insulating substrate 2 when the nozzle of the spray chamber 7 needs to be disassembled for cleaning. Furthermore, the electronic amplification block amplifies the phase signal detected by the detection electrode 803, preventing interference.

[0078] Preferably, an electronic amplification block placement cavity 23 is provided around the outer periphery of the lower surface of the insulating substrate 2, located within the nozzle lower cavity 6. Figure 5 and Figure 13 The electronic amplifier block is located inside the electronic amplifier block placement cavity 23, and the electronic amplifier block placement cavity 23 is filled with insulating glue around the electronic amplifier block.

[0079] Two high-voltage electrode holders 2501 are also provided on the upper surface of the insulating substrate 2, see Figures 1-3 , Figures 6-9 as well as Figure 12 and Figure 14 Each high-voltage electrode holder 2501 is provided with a high-voltage deflection electrode conductive element. Each high-voltage deflection electrode 2502 of the high-voltage deflection electrode assembly is mounted on the corresponding high-voltage electrode holder 2501 and is electrically connected to the control circuit inside the chassis through the corresponding high-voltage deflection electrode conductive element and the high-voltage wire that passes through the nozzle lower cavity 6 and the throat tube in sequence. An isolation cavity 29 is provided on the lower surface of the insulating substrate 2 at a position corresponding to each high-voltage deflection electrode conductive element, which is located in the nozzle lower cavity 6. See Figure 5 and Figure 13 The end of the high-voltage conductor that is connected to the high-voltage deflection plate conductive component is called the high-voltage conductor conductive component connection end. The part of the high-voltage conductor near the high-voltage conductor conductive component connection end is located in the corresponding isolation cavity 29, and the isolation cavity 29 is filled with insulating glue around the high-voltage conductor.

[0080] The portion of the high-voltage conductor located inside the nozzle lower chamber 6 and the recovery tank connecting pipe are both arranged outside the electronic amplifier block placement chamber 23.

[0081] The design of the nozzle lower cavity 6 facilitates the arrangement of various wires within it. The combination of the isolation cavity 29 and the insulating adhesive prevents high-voltage leakage near the connection points of the high-voltage wires. Since the electronic amplifier block is located within the electronic amplifier block placement cavity 23, the portion of the high-voltage wire inside the nozzle lower cavity 6 is positioned outside the cavity. This arrangement of the electronic amplifier block placement cavity 23 ensures that the portion of the high-voltage wire inside the nozzle lower cavity 6 is spaced a certain distance from the electronic amplifier block, preventing interference from the high-voltage electricity transmitted by the wire. Furthermore, the electronic amplifier block placement cavity 23 is filled with insulating adhesive, and the recovery tank connecting pipe is positioned outside the cavity. This insulating adhesive covering of the electronic amplifier block prevents condensation on the recovery tank connecting pipe, thus preventing the electronic amplifier block from becoming damp.

[0082] Among them, an external cleaning nozzle 24 is provided on one side of the spray path on the upper surface of the insulating substrate 2, see Figures 1-3 as well as Figures 6-9 The external cleaning nozzle 24 is connected to the cleaning fluid tank via an external cleaning pipe that passes through the lower chamber 6 of the printhead and the throat and is equipped with a second cleaning fluid pressurization pump. The cleaning fluid tank is connected to the inner cleaning pipe and the external cleaning pipe via a cleaning three-way valve. The cleaning fluid sprayed from the external cleaning nozzle 24 is used to clean the residual ink droplets in the first upper chamber of the printhead.

[0083] When it is necessary to clean the residual ink droplets in the first upper chamber of the printhead, first open the printhead flip cover 3 and turn off the high-pressure output of the high-pressure deflection plate assembly. Then, control the cleaning three-way valve to connect the cleaning fluid tank to the external cleaning pipe. In this way, the cleaning fluid in the cleaning fluid tank is sprayed into the first upper chamber of the printhead through the external cleaning pipe and the external cleaning nozzle 24 under the pressure of the second cleaning fluid pressurizing pump, thereby cleaning the residual ink droplets in the first upper chamber of the printhead.

[0084] Preferably, the external cleaning nozzle 24 is provided with three sets of spray ports. The spray direction of the first set of spray ports is aligned with the nozzle of the spray chamber 7, the spray direction of the second set of spray ports is aligned with the charging electrode 802, and the spray direction of the third set of spray ports is aligned with the high-voltage deflection plate assembly.

[0085] Preferably, a magnetic induction switch is installed on one side of the recycling tank 9 on the nozzle housing 1, and a magnet is installed on the nozzle flip cover 3 at a position corresponding to the magnetic induction switch. The magnetic induction switch is connected to the controller on the control circuit inside the chassis.

[0086] When it is necessary to clean the outside of the printing components in the first upper cavity of the printhead or to maintain the printing components in the first upper cavity of the printhead, the flip cover 3 on the printhead is opened. At this time, the magnetic induction switch detects that the flip cover 3 on the printhead is open by sensing the distance of the magnet, and controls the controller to shut off the high voltage output of the high voltage deflection plate assembly.

[0087] The insulating substrate 2 is provided with a crystal oscillator conductive element. The crystal oscillator in the spray cavity 7 is electrically connected to the control circuit in the chassis through the crystal oscillator conductive element and ordinary wires that pass through the lower cavity 6 of the nozzle and the throat tube in sequence.

[0088] In one embodiment, an observation port 301 is provided on the flip cover 3 of the nozzle head at a position corresponding to the nozzle of the spray chamber 7, see Figure 1 , Figure 3 , Figure 6 and Figure 7 A magnifying glass is installed at the observation port 301 to observe the separation state of the ink droplets ejected from the nozzle of the spray chamber 7; the lower cover 26 of the printhead housing 1 is detachably and sealingly connected to the lower opening of the lower chamber 6 of the printhead, see Figure 4 The nozzle housing 1 is slidably connected to the nozzle head sliding cover 27 at the upper opening of the second upper cavity 5 of the nozzle, see Figure 1 , Figure 6 , Figure 7 and Figure 9 .

[0089] The magnifying glass allows for easy observation of the separation of ink droplets ejected from the nozzle of the spray chamber 7. The lower chamber 6 of the printhead can be opened by opening the lower cover 26, and the second upper chamber 5 of the printhead can be opened by sliding the upper cover 27, which facilitates the maintenance of the ink solenoid valve 10, the return solenoid valve 11, the cleaning solenoid valve 12, and the recovery solenoid valve 13.

[0090] In one embodiment, the nozzle housing 1 is die-cast from aluminum, and the insulating substrate 2 is injection molded from Keep material; wherein the ink pipe connector 15, the return pipe connector 16, the internal cleaning pipe connector 17, the recovery pipe connector 18, the spray chamber inlet pipe connector 19, the spray chamber outlet pipe connector 20, and the recovery tank connection pipe connector 21 are all pagoda connectors; the crystal oscillator frequency in the spray chamber 7 is 62.5KHz, 88KHz, and 125KHz. Taking the spray chamber 7 with a 62.5KHz crystal oscillator as an example, the ink line sprayed from the nozzle of the spray chamber 7 is uniformly broken, and the ink line is broken into 62,500 uniform ink dots per second.

[0091] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A four-valve printhead for an inkjet printer, characterized in that: The device includes a nozzle housing (1), an insulating substrate (2) detachably connected to the nozzle housing (1), and a nozzle head flip cover (3) rotatably connected above the insulating substrate (2). The nozzle head flip cover (3) and the insulating substrate (2) cooperate to form a first upper cavity of the nozzle. A valve seat (4) is fixed inside the nozzle housing (1) on one side of the first upper cavity of the nozzle. A second upper cavity (5) of the nozzle is formed in the area above the valve seat (4) inside the nozzle housing (1), and a lower cavity (6) of the nozzle is formed in the area below the first upper cavity and the second upper cavity (5). A spray cavity (7), a charging detection electrode assembly, and a high-voltage deflection electrode plate are sequentially arranged along the spray path on the upper surface of the insulating substrate (2). The assembly includes a recycling trough (9) on the downstream side of the high-voltage deflection plate assembly on the nozzle housing (1), a high-voltage wire electrically connected to the high-voltage deflection plate assembly is arranged in the lower cavity (6) of the nozzle, and the charging detection electrode seat (801) of the charging detection electrode assembly is detachably connected to the insulating substrate (2); an ink solenoid valve (10), a return solenoid valve (11), a cleaning solenoid valve (12) and a recycling solenoid valve (13) are arranged sequentially on the upper surface of the valve seat (4), and a valve channel plate (14) is arranged on the lower surface of the valve seat (4) and is connected to the ink solenoid valve (10), the return solenoid valve (11), the cleaning solenoid valve (12) and the recycling solenoid valve (13).

2. A four-valve printhead for an inkjet printer according to claim 1, characterized in that: One end of the valve channel plate (14) is connected in sequence to the ink pipe connector (15), the return pipe connector (16), the internal cleaning pipe connector (17) and the recovery pipe connector (18), and the other end is connected in sequence to the spray chamber inlet pipe connector (19), the spray chamber outlet pipe connector (20) and the recovery tank connection pipe connector (21). The ink pipe connector (15) is connected to the ink tank inside the machine housing of the inkjet printer via an ink pipe with an ink pressurizing pump; the return pipe connector (16) is connected to one end of a return pipe with a return suction pump, and the other end of the return pipe is connected to the ink tank and the liquid storage tank inside the machine housing via a return three-way valve; the internal cleaning pipe connector (17) is connected to the cleaning liquid tank inside the machine housing via an internal cleaning pipe with a first cleaning liquid pressurizing pump; the recovery pipe connector (18) is connected to the ink tank via a recovery pipe; The ink pipe connector (15) is connected to the ink solenoid valve (10) in sequence via the valve channel plate (14) and the valve seat (4). The ink solenoid valve (10) is connected to the spray chamber inlet pipe connector (19) in sequence via the valve seat (4) and the valve channel plate (14). The return pipe connector (16) is connected to the return solenoid valve (11) in sequence via the valve channel plate (14) and the valve seat (4). The return solenoid valve (11) is connected to the spray chamber outlet pipe connector (20) in sequence via the valve seat (4) and the valve channel plate (14). The internal cleaning pipe connector (17) is connected to the cleaning solenoid valve (12) in sequence through the valve channel plate (14) and the valve seat (4). The cleaning solenoid valve (12) is connected to the spray chamber inlet pipe connector (19) in sequence through the valve seat (4) and the valve channel plate (14). The recovery pipe connector (18) is connected to the recovery solenoid valve (13) in sequence through the valve channel plate (14) and the valve seat (4). The recovery solenoid valve (13) is connected to the recovery tank connection pipe connector (21) in sequence through the valve seat (4) and the valve channel plate (14). The spray chamber inlet pipe joint (19) is connected to the inlet of the spray chamber (7) through the spray chamber inlet pipe, the spray chamber outlet pipe joint (20) is connected to the outlet of the spray chamber (7) through the spray chamber outlet pipe, and the recovery tank connection pipe joint (21) is connected to the recovery tank (9) through the recovery tank connection pipe. The four-valve printhead performs the printing work. The ink solenoid valve (10), the return solenoid valve (11) and the recovery solenoid valve (13) work together. The inlet pipe joint (19) of the spray chamber is connected to the ink solenoid valve (10) in sequence through the valve channel plate (14) and the valve seat (4). The other end of the return pipe is connected to the ink tank. The four-valve nozzle performs cleaning work inside the spray chamber (7). The cleaning solenoid valve (12) and the return solenoid valve (11) work together. The spray chamber inlet pipe joint (19) is connected to the cleaning solenoid valve (12) in sequence through the valve channel plate (14) and the valve seat (4). The other end of the return pipe is connected to the liquid storage tank.

3. A four-valve printhead for an inkjet printer according to claim 2, characterized in that: The nozzle housing (1) has an opening at one end corresponding to both the second upper cavity (5) and the lower cavity (6) of the nozzle, forming a throat connection port (101). The nozzle housing (1) is detachably connected to a throat connector (22) at the throat connection port (101). The throat connector (22) includes a throat connector frame (2201), and a throat connection tube (2202) is integrally formed on the outer end of the throat connector frame (2201). The axis of the throat connection tube (2202) is relative to the throat. The center lines of the frame opening of the connector frame (2201) are not parallel. The inner end of the throat connector frame (2201) is detachably and sealed to the nozzle housing (1) at the throat connection port (101). The free end of the throat connection tube (2202) is connected to the chassis through the throat tube. The throat connector (22) can rotate 180° around the rotation axis perpendicular to the plane where the throat connection port (101) is located, so that the axis of the throat connection tube (2202) switches between the first direction and the second direction.

4. A four-valve printhead for an inkjet printer according to claim 3, characterized in that: The spray cavity inlet pipe, spray cavity outlet pipe, and recovery tank connecting pipe are all arranged in the lower cavity (6) of the nozzle. The insulating substrate (2) has an insulating substrate spray cavity connection port at the position corresponding to the inlet and outlet of the spray cavity (7). One end of the spray cavity inlet pipe is connected to the inlet of the spray cavity (7) through one of the insulating substrate spray cavity connection ports, and one end of the spray cavity outlet pipe is connected to the outlet of the spray cavity (7) through the other insulating substrate spray cavity connection port. The ink tube, return tube, internal cleaning tube, and recovery tube all pass through the lower cavity (6) of the nozzle and the throat tube in sequence.

5. A four-valve printhead for an inkjet printer according to claim 3, characterized in that: The charging detection electrode holder (801) is detachably connected to the substrate holder (31) fixed on the upper surface of the insulating substrate (2) by bolts; the charging detection electrode assembly includes a charging electrode (802) and a detection electrode (803) installed sequentially on the charging detection electrode holder (801) along the spray path. The charging electrode (802) and the detection electrode (803) are respectively electrically connected to the electronic amplifier block arranged in the lower cavity (6) of the nozzle through a common wire that passes through the inner cavity of the charging and detection electrode base (801) and the insulating substrate (2) in sequence; or the charging electrode (802) and the detection electrode (803) are both electrically connected to the electronic amplifier block through a spring-loaded connector (804) that passes through the inner cavity of the charging and detection electrode base (801) and the insulating substrate (2) in sequence. The electronic amplifier is electrically connected to the control circuit located inside the chassis via ordinary wires passing through the throat tube.

6. A four-valve printhead for an inkjet printer according to claim 5, characterized in that: The lower surface of the insulating substrate (2) is provided with an electronic amplification block placement cavity (23) located in the nozzle lower cavity (6) around the outer side of the electronic amplification block. The electronic amplification block is located in the electronic amplification block placement cavity (23), and the electronic amplification block placement cavity (23) is filled with insulating glue around the electronic amplification block. Two high-voltage electrode seats (2501) are also provided on the upper surface of the insulating substrate (2). Each high-voltage electrode seat (2501) is provided with a high-voltage deflection electrode conductive element. Each high-voltage deflection electrode (2502) of the high-voltage deflection electrode assembly is installed on the corresponding high-voltage electrode seat (2501) and is electrically connected to the control circuit in the chassis through the corresponding high-voltage deflection electrode conductive element and the high-voltage wire passing through the nozzle lower cavity (6) and the throat tube in sequence. An isolation cavity (29) is provided in the nozzle lower cavity (6) at the position corresponding to each high-voltage deflection electrode conductive element on the lower surface of the insulating substrate (2). The end of the high-voltage wire connected to the high-voltage deflection electrode conductive element is called the high-voltage wire conductive element connection end. The part of the high-voltage wire near the high-voltage wire conductive element connection end is in the corresponding isolation cavity (29), and the isolation cavity (29) is filled with insulating glue around the high-voltage wire. The portion of the high-voltage conductor located inside the nozzle lower cavity (6) and the recovery tank connecting pipe are both arranged outside the electronic amplifier block placement cavity (23).

7. A four-valve printhead for an inkjet printer according to claim 3, characterized in that: An external cleaning nozzle (24) is provided on one side of the spray path on the upper surface of the insulating substrate (2). The external cleaning nozzle (24) is connected to the cleaning liquid tank through an external cleaning pipe that passes through the lower cavity (6) of the printhead and the throat and is equipped with a second cleaning liquid pressurizing pump. The cleaning liquid tank is connected to the inner cleaning pipe and the outer cleaning pipe through a cleaning three-way valve. The cleaning liquid sprayed through the external cleaning nozzle (24) is used to clean the residual ink droplets in the first upper cavity of the printhead.

8. A four-valve printhead for an inkjet printer according to claim 7, characterized in that: The external cleaning nozzle (24) is provided with three sets of spray ports. The spray direction of the first set of spray ports is aligned with the nozzle of the spray chamber (7), the spray direction of the second set of spray ports is aligned with the charging electrode (802), and the spray direction of the third set of spray ports is aligned with the high voltage deflection plate assembly.

9. A four-valve printhead for an inkjet printer according to claim 3, characterized in that: The insulating substrate (2) is provided with a crystal oscillator conductive element. The crystal oscillator in the spray cavity (7) is electrically connected to the control circuit in the chassis through the crystal oscillator conductive element and ordinary wires that pass through the lower cavity (6) of the nozzle and the throat tube in sequence.

10. A four-valve printhead for an inkjet printer according to claim 2, characterized in that: An observation port (301) is provided on the flip cover (3) of the printhead at a position corresponding to the nozzle of the spray chamber (7). A magnifying glass is installed at the observation port (301) to observe the separation state of the ink droplets ejected from the nozzle of the spray chamber (7). The printhead housing (1) is detachably and sealingly connected to the lower cover (26) of the printhead lower chamber (6). The printhead housing (1) is slidably connected to the upper cover (27) of the printhead upper chamber (5) of the printhead sliding cover (27).

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