Liquid ejection device

Abstract

The present application provides a liquid ejection device that can reduce the possibility of foreign matter generated at a gas-liquid interface flowing further downstream than a liquid storage portion. The device is provided with: an ejection portion (12) that can eject liquid toward a medium; a supply flow path (21) that can supply liquid to the ejection portion (12); a liquid storage portion (22) that is connected to the supply flow path (21) and can store liquid, forming a gas-liquid interface (36) at which liquid and air are in contact; a first filter (23) that is disposed below the gas-liquid interface (36) and divides the supply flow path (21) and the liquid storage portion (22); an adjustment mechanism (14) that can raise the height of the gas-liquid interface (36) within the liquid storage portion (22); and a control portion (15) that controls the adjustment mechanism (14).

Description

Technical Field

[0001] This invention relates to liquid jetting devices such as printers. Background Technology

[0002] For example, as in Patent Document 1, there is a liquid ejection device, an example of a liquid ejection apparatus, which ejects ink, an example of a liquid, from a liquid nozzle, an example of a ejection section, and performs printing. The liquid ejection device includes a flow path, an example of a supply flow path, a bubble chamber, an example of a liquid storage section, and a bubble chamber filter, an example of a first filter. The flow path allows ink to flow from a liquid supply source to the liquid nozzle. The bubble chamber is provided in the flow path. The bubble chamber stores air bubbles contained in the ink.

[0003] The liquid inside the bubble chamber is prone to producing foreign matter at the gas-liquid interface where it comes into contact with the stored air. A bubble chamber filter is positioned between the gas-liquid interface and the flow path. Therefore, the bubble chamber filter captures and collects the foreign matter generated at the gas-liquid interface before it flows into the flow path.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2019-77107

[0005] In Patent Document 1, the position of the gas-liquid interface in the bubble chamber varies depending on the amount of air stored in the liquid storage section. That is, the gas-liquid interface is located below the gas-liquid interface when there is more air. In particular, when the gas-liquid interface descends to a position lower than the bubble chamber filter, foreign matter generated at the gas-liquid interface cannot be captured by the bubble chamber filter, and the foreign matter flows into the supply path. Summary of the Invention

[0006] A liquid injection device for solving the above-mentioned technical problems includes: an injection unit capable of injecting liquid into a medium; a supply flow path capable of supplying the liquid to the injection unit; a liquid storage unit connected to the supply flow path capable of storing the liquid and forming a gas-liquid interface where the liquid and air meet; a first filter disposed below the gas-liquid interface, dividing the supply flow path and the liquid storage unit; an adjustment mechanism capable of raising the height of the gas-liquid interface within the liquid storage unit; and a control unit controlling the adjustment mechanism. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of one embodiment of a liquid injection device.

[0008] Explanation of reference numerals in the attached figures

[0009] 11: Liquid injection device; 12: Injection section; 13: Supply mechanism; 14: Adjustment mechanism; 15: Control section; 16: Mounting section; 17: Liquid supply source; 19: Nozzle; 21: Supply flow path; 22: Liquid storage section; 23: First filter; 24: Second flexible membrane; 25: Drive section; 26: Second filter; 27: Branch section; 28: Branch flow path; 29: Pump; 30: Liquid level detection sensor; 32: Supply needle; 34: Supply chamber; 36: Gas-liquid interface; 38: First flexible membrane; 39: Valve section; 40: Suction section; 42: Cover; 43: Discharge flow path; 44: Pressure reducing section; 45: Waste liquid collection section; 46: Lip; D: Liquid delivery direction; Z: Vertical direction. Detailed Implementation

[0010] Implementation

[0011] Liquid injection device

[0012] Hereinafter, one embodiment of the liquid jetting device will be described with reference to the accompanying drawings. The liquid jetting device is, for example, an inkjet printer that jets ink, as a liquid, onto media such as paper, fabric, vinyl resin, plastic parts, and metal parts for printing.

[0013] In the accompanying drawings, it is assumed that the liquid injection device 11 is placed on a horizontal plane, with the Z-axis representing the direction of gravity and the X and Y axes representing the directions along the horizontal plane. The X, Y, and Z axes are orthogonal to each other. In the following description, the direction parallel to the Z-axis is referred to as the vertical direction Z, the area above the vertical direction Z is simply referred to as above or above, and the area below the vertical direction Z is simply referred to as below or below.

[0014] The liquid injection device 11 includes an injection unit 12, a supply mechanism 13, an adjustment mechanism 14, and a control unit 15. The liquid injection device 11 may also include a mounting unit 16. A liquid supply source 17 for containing liquid is detachably mounted on the mounting unit 16. The liquid supply source 17 can also be replenished with liquid. If liquid replenishment is possible, the liquid supply source 17 can also be fixed to the mounting unit 16.

[0015] The jetting unit 12 has multiple nozzles 19. The jetting unit 12 is capable of jetting liquid onto a medium (not shown). The jetting unit 12 jets liquid from the nozzles 19 to perform printing on the medium. The jetting unit 12 can also be a serial type that jets liquid while moving to perform printing. The jetting unit 12 can also be a linear type that is set as a strip in the width direction of the medium and jets liquid onto the conveyed medium to perform printing.

[0016] The supply mechanism 13 includes a supply flow path 21, a liquid storage section 22, and a first filter 23. The supply mechanism 13 may also include a second flexible membrane 24, a drive section 25, a second filter 26, a branch section 27, a branch flow path 28, a pump 29, and a liquid level detection sensor 30.

[0017] The upstream end of the supply flow path 21 can also be constituted by a supply needle 32. The supply needle 32 is provided on the mounting part 16. By inserting the supply needle 32 into the liquid supply source 17 mounted on the mounting part 16, the liquid contained in the liquid supply source 17 can be discharged.

[0018] The supply flow path 21 is capable of supplying liquid to the injection section 12. The supply flow path 21 supplies liquid from the liquid supply source 17 installed on the mounting section 16 to the injection section 12. The supply flow path 21 can also supply liquid via a water head. In this embodiment, the direction of the liquid flowing in the supply flow path 21 is defined as the liquid delivery direction D. The upstream end of the liquid delivery direction D of the supply flow path 21 is connected to the liquid supply source 17, and the downstream end of the liquid delivery direction D is connected to the injection section 12.

[0019] The supply flow path 21 may also have a supply chamber 34. The supply chamber 34 is located below the liquid storage section 22. The supply chamber 34 is separated from the liquid storage section 22 by a first filter 23. The supply chamber 34 is a space located below the first filter 23. Liquid supplied from the liquid supply source 17 is supplied to the injection section 12 through the supply chamber 34. The liquid in the supply chamber 34 passes through the first filter 23 due to the pressure difference between the supply chamber 34 and the liquid storage section 22. That is, liquid can flow from the supply chamber 34 into the liquid storage section 22 through the first filter 23. Liquid in the liquid storage section 22 can flow into the supply chamber 34 through the first filter 23.

[0020] The second flexible membrane 24 is positioned lower than the first filter 23. The second flexible membrane 24 may also form part of the wall of the supply chamber 34. For example, the second flexible membrane 24 may also form the bottom of the supply chamber 34. The second flexible membrane 24 is deformable. The second flexible membrane 24 may also be formed of an elastic material such as silicone rubber.

[0021] The drive unit 25 enables the second flexible membrane 24 to move to Figure 1 The second retreat position shown by the solid line and Figure 1 The second forward position is indicated by the double-dotted line. The second forward position is the position where the material advances towards the first filter 23 compared to the second retracted position. The drive unit 25 changes the volume of the supply flow path 21 by moving the second flexible membrane 24. Specifically, the drive unit 25 reduces the volume of the supply chamber 34 by pressing the second flexible membrane 24 from the second retracted position to the second forward position.

[0022] The liquid storage section 22 is connected to the supply flow path 21. The liquid storage section 22 is positioned above the supply flow path 21. The liquid storage section 22 is capable of storing liquid. The liquid storage section 22 is capable of recovering air bubbles from the liquid. In this embodiment, the air bubbles gathered in the liquid storage section 22 are also referred to as air. A gas-liquid interface 36, where the liquid and air come into contact, is formed in the liquid storage section 22. The gas-liquid interface 36 is the upper surface of the stored liquid, also referred to as the liquid surface.

[0023] The first filter 23 divides the supply flow path 21 and the liquid storage section 22. The first filter 23 can be installed horizontally or at an angle. In this embodiment, the space below the first filter 23 is the supply chamber 34, and the space above the first filter 23 is the liquid storage section 22. Therefore, when the gas-liquid interface 36 is located in the liquid storage section 22, the first filter 23 is located below the gas-liquid interface 36. At least a portion of the gas-liquid interface 36 in the liquid storage section 22 and at least a portion of the first filter 23 are arranged in the vertical direction Z. The liquid storage section 22, the first filter 23, and the supply chamber 34 are arranged in the vertical direction Z.

[0024] The second filter 26 may also be provided in the supply flow path 21 on the downstream side, closer to the liquid delivery direction D than the liquid storage section 22. The second filter 26 may also be provided on the downstream side, closer to the liquid delivery direction D than the supply chamber 34. Alternatively, the second filter 26 may be provided between the supply chamber 34 and the branch section 27 in the liquid delivery direction D.

[0025] The first filter 23 and the second filter 26 can be made of materials such as mesh, porous materials, or porous plates with fine through-holes. Mesh filters include metal wire mesh, resin mesh, sieve filters, and metal fibers. Metal fiber filters include felt filters made by forming fine stainless steel wire into a felt shape, and sintered metal filters made by compressing and sintering fine stainless steel wire. Porous plate filters include electroformed metal filters, electron beam processed metal filters, and laser beam processed metal filters.

[0026] The first filter 23 and the second filter 26 can be the same filter, or they can be filters of different types and shapes. For example, the mesh size of the second filter 26 can be finer than that of the first filter 23.

[0027] Branch 27 causes branch flow path 28 to branch from supply flow path 21. That is, branch flow path 28 separates from supply flow path 21 on a downstream side closer to the liquid delivery direction D than liquid storage section 22. Branch flow path 28 branches from a downstream side closer to the liquid delivery direction D than supply chamber 34. In this embodiment, the side of branch flow path 28 that branches from supply flow path 21 is referred to as one end side, and the opposite side is referred to as the other end side. One end side of branch flow path 28 is connected to branch 27. The other end side of branch flow path 28 is connected to liquid storage section 22. Branch flow path 28 connects supply flow path 21 and liquid storage section 22.

[0028] Pump 29 circulates the liquid within branch flow path 28. Pump 29 causes the liquid to flow from one end to the other within branch flow path 28. Pump 29 delivers liquid from supply chamber 34 downstream in the delivery direction D to liquid storage section 22 via branch flow path 28. Pump 29 circulates the liquid within supply chamber 34, supply flow path 21 between supply chamber 34 and branch section 27, branch flow path 28, and liquid storage section 22. The liquid circulates while passing through first filter 23 and second filter 26.

[0029] The liquid level sensor 30 detects that the gas-liquid interface 36 is located at a predetermined position above the first filter 23. For example, the liquid level sensor 30 may also be a contact sensor that detects liquid contact. The liquid level sensor 30 may also include an electrode disposed at a predetermined position within the liquid storage section 22. The liquid level sensor 30 may also detect that the gas-liquid interface 36 has dropped to a predetermined position by detecting the change in resistance when the liquid is in contact with the electrode and when the liquid is not in contact with the electrode. The predetermined position may also be located above the position connecting the branch flow path 28.

[0030] The adjustment mechanism 14 may also have a first flexible membrane 38, a valve section 39, and a suction section 40.

[0031] The first flexible membrane 38 is deformable. The first flexible membrane 38 can also be positioned above the gas-liquid interface 36. The first flexible membrane 38 can also be positioned above the liquid level detection sensor 30. The first flexible membrane 38 can also form part of the wall surface in the liquid storage section 22. For example, the first flexible membrane 38 can also form the top of the liquid storage section 22.

[0032] The first flexible membrane 38 can move to Figure 1 The first retreat position shown by the solid line and Figure 1The first advancing position is indicated by the double-dotted line. The first advancing position is the position where the membrane advances towards the gas-liquid interface 36 compared to the first retreating position. The first advancing position is the position closer to the first filter 23 than the first retreating position. The first flexible membrane 38 moves with changes in pressure within the liquid storage section 22. The first flexible membrane 38 may also be formed of an elastic material such as silicone rubber.

[0033] A valve 39 is provided on the supply flow path 21, which is closer to the upstream side of the liquid delivery direction D than the liquid storage section 22. The valve 39 is also closer to the upstream side of the supply chamber 34, which is closer to the upstream side of the liquid delivery direction D. The valve 39 allows the flow of liquid in the supply flow path 21 by opening. The valve 39 restricts the flow of liquid in the supply flow path 21 by closing.

[0034] The suction unit 40 may also include a cover 42, a discharge path 43, a pressure reducing unit 44, and a waste liquid receiving unit 45. The waste liquid receiving unit 45 may also be detachably provided relative to the liquid injection device 11.

[0035] The cap 42 is capable of receiving liquid discharged from the nozzle 19. The cap 42 may also have a lip 46. The lip 46 is configured to be annular, forming an opening in the cap 42.

[0036] The cover 42 can also be configured to move to a cover position (not shown) of the cover injection section 12 and to open the injection section 12. Figure 1 The separation position is shown.

[0037] When the cap 42 is in the pressure-fit position, the lip 46 contacts the spray section 12. The cap 42 in the pressure-fit position is blocked by the spray section 12 through its opening, forming a closed space for the nozzle 19 opening. When the lip 46 is formed, for example, of elastically deformable rubber or an elastomer, the sealing performance of the closed space can be improved. When the cap 42 is in the separation position, the lip 46 separates from the spray section 12. The cap 42 in the separation position opens its opening.

[0038] The upstream end of the discharge path 43 is connected to the cover 42, and the downstream end is connected to the waste liquid receiving section 45. The discharge path 43 may also be constructed of a tube, for example, that can deform to follow the movement of the cover 42. The discharge path 43 is capable of discharging liquid from the cover 42 to the waste liquid receiving section 45.

[0039] The pressure reducing unit 44 can also be provided on the discharge flow path 43. The pressure reducing unit 44 is, for example, a pipe pump. The pressure reducing unit 44 can reduce the pressure of the space inside the cover 42 via the discharge flow path 43.

[0040] The suction unit 40 performs a suction operation by depressurizing the contents of the cap 42 with the cap 42 in the press-fit position using the depressurization unit 44. When the contents of the cap 42 are depressurized, liquid is discharged from the nozzle 19 while liquid is supplied to the injection unit 12 from the supply flow path 21. That is, the suction unit 40 performs a suction operation to draw liquid from the liquid storage unit 22, causing the liquid in the liquid storage unit 22 to flow downstream in the liquid delivery direction D. The liquid in the liquid storage unit 22 flows downstream in the liquid delivery direction D through the first filter 23 and the supply chamber 34.

[0041] The control unit 15 controls the adjustment mechanism 14. The control unit 15 uniformly controls the driving of each mechanism in the liquid injection device 11, controlling various actions performed by the liquid injection device 11. The control unit 15 can be configured as a circuit including α, β, or γ, where α is one or more processors executing various processes according to a computer program, β is one or more dedicated hardware circuits executing at least a portion of the various processes, and γ is a combination thereof. The hardware circuit is, for example, an application-specific integrated circuit. The processor includes a CPU (Central Processing Unit), and memories such as RAM (Random Access Memory) and ROM (Read-Only Memory), storing program code or instructions configured to cause the CPU to execute processes. Memory, or computer-readable medium, includes all readable media that can be accessed by a general-purpose or special-purpose computer.

[0042] The role of the implementation method

[0043] The function of this embodiment will be explained.

[0044] Air bubbles may sometimes be introduced into the supply flow path 21. These bubbles may be generated, for example, when air enters the supply needle 32 during the connection or disconnection of the liquid supply source 17 to the supply needle 32. They may also be generated, for example, when air dissolved in the liquid becomes gas. The bubbles flow along with the liquid in the supply flow path 21 in the delivery direction D. The bubbles delivered to the supply chamber 34 are propelled by buoyancy through the first filter 23 and accumulate in the liquid storage section 22.

[0045] However, depending on factors such as the type of the first filter 23 and the size of the bubbles, sometimes bubbles may not pass through the first filter 23 and remain below it. The control unit 15 can also control the drive of the drive unit 25 to transport the bubbles in the supply chamber 34 to the liquid storage unit 22.

[0046] Specifically, the drive unit 25 moves the second flexible membrane 24 when the gas-liquid interface 36 is positioned above the first filter 23. The drive unit 25 moves the second flexible membrane 24 from... Figure 1 The second retreat position indicated by the solid line is towards Figure 1The second forward position, indicated by the double-dotted line, advances, thereby reducing the volume of the supply flow path 21. When the second flexible membrane 24 moves from the second retracted position to the second forward position, the volume of the supply chamber 34 decreases, and the pressure inside the supply chamber 34 increases, so that air bubbles inside the supply chamber 34 can easily pass through the first filter 23.

[0047] Bubbles that accumulate in the liquid storage section 22 form air clusters, creating a gas-liquid interface 36 between the liquid and the air. Because the liquid is in contact with air at the gas-liquid interface 36, the surface of the liquid tends to dry out. This surface-dried liquid locally concentrates, sometimes causing dispersion disruption. For example, if the liquid contains resin components, the resin particles may become large and form foreign matter due to their binding together. Such foreign matter is difficult to dissolve back into the liquid. Therefore, once foreign matter is formed, it tends to remain intact. However, a first filter 23 is provided between the gas-liquid interface 36 and the supply flow path 21. The first filter 23 traps and collects the foreign matter, keeping it in the liquid storage section 22.

[0048] The gas-liquid interface 36 within the liquid storage section 22 moves according to the amount of air within the liquid storage section 22. Specifically, the gas-liquid interface 36 descends as the amount of air increases. The adjustment mechanism 14 can raise the height of the gas-liquid interface 36 within the liquid storage section 22. The control unit 15 raises the gas-liquid interface 36 before the liquid storage section 22 is filled with air. The control unit 15 raises the gas-liquid interface 36 before it descends to the first filter 23.

[0049] In this embodiment, the control unit 15, based on the detection of the liquid level sensor 30, controls the adjustment mechanism 14 to raise the gas-liquid interface 36 when it drops to a predetermined position. For example, the control unit 15 may also determine that the gas-liquid interface 36 has dropped to a predetermined position when switching from a state where the liquid level sensor 30 detects liquid to a state where it does not detect liquid.

[0050] To raise the gas-liquid interface 36, the control unit 15 first performs a lowering action. The lowering action involves the suction unit 40 performing a suction action with the valve unit 39 closed, thereby lowering the gas-liquid interface 36. During the lowering action, the pressure in the liquid storage unit 22 is reduced. Therefore, the first flexible membrane 38 moves from... Figure 1 Advance to the first retreat position indicated by the solid line. Figure 1 The first forward position is indicated by the double-dotted line. The first flexible membrane 38 reduces the volume of the liquid storage section 22.

[0051] When the gas-liquid interface 36 descends to a position lower than the first filter 23, the gas-liquid interface 36 forms a supply chamber 34. Therefore, the air stored in the liquid storage section 22 is transported downstream in the liquid delivery direction D via the supply chamber 34. That is, the liquid storage section 22 becomes a state where air is discharged and the pressure decreases. Therefore, when the valve section 39 is opened while the gas-liquid interface 36 has descended to a position lower than the first filter 23 through the descending action, the gas-liquid interface 36 rises to a position higher than its position before the descending action. The control unit 15 can open the valve section 39 after the suction action has stopped, or it can open the valve section 39 while the suction action is in progress.

[0052] Effects of the implementation method

[0053] The effects of this implementation method will be explained.

[0054] (1) The first filter 23 divides the supply flow path 21 and the liquid storage section 22. The adjustment mechanism 14 can adjust the height of the gas-liquid interface 36 in the liquid storage section 22. Therefore, by controlling the adjustment mechanism 14, the control unit 15 can adjust the gas-liquid interface 36 to be located higher than the first filter 23. That is, it is possible to maintain the state in which the first filter 23 is located below the gas-liquid interface 36, thereby reducing the possibility that the foreign flow generated at the gas-liquid interface 36 will flow further downstream than the liquid storage section 22.

[0055] (2) The control unit 15 performs a suction operation by closing the valve 39, causing the gas-liquid interface 36 to drop below the first filter 23. As a result, the air and liquid in the liquid storage unit 22 are sent downstream in the liquid delivery direction D. Therefore, when the valve 39 is opened and liquid is supplied from upstream in the liquid delivery direction D, the gas-liquid interface 36 in the liquid storage unit 22 rises from its original position. Thus, the gas-liquid interface 36 can be raised with a simple configuration.

[0056] (3) The first flexible membrane 38 moves from the first retracted position to the first forward position as it descends, thereby reducing the volume of the liquid storage section 22. Therefore, the gas-liquid interface 36 can be easily lowered by the descending action, and the gas-liquid interface 36 can be easily raised by opening the valve section 39.

[0057] (4) The gas-liquid interface 36 descends, for example, as the air in the liquid storage section 22 increases. When the gas-liquid interface 36 descends to a predetermined position, the control unit 15 controls the adjustment mechanism 14 to raise the gas-liquid interface 36. The predetermined position is a position higher than the first filter 23. Therefore, the gas-liquid interface 36 can be positioned higher than the first filter 23.

[0058] (5) Sometimes, air bubbles in the supply flow path 21 fail to pass through the first filter 23 and remain below it. To address this, the drive unit 25 reduces the volume of the supply flow path 21 by advancing the second flexible membrane 24 from the second retracted position to the second forward position. This increases the pressure within the supply flow path 21, making it easier for air bubbles remaining below the first filter 23 to pass through. Therefore, the air bubbles can be easily collected in the liquid storage unit 22.

[0059] (6) The second filter 26 is provided on the supply flow path 21, which is closer to the downstream side than the liquid storage section 22. The mesh of the second filter 26 is finer than that of the first filter 23. Therefore, even if foreign matter passes through the first filter 23, the foreign matter can be captured and collected by the second filter 26.

[0060] (7) Branch flow path 28 connects supply flow path 21 and liquid storage section 22, which are located further downstream than liquid storage section 22. Pump 29 circulates the liquid within branch flow path 28. The liquid is delivered in the order of supply flow path 21, branch flow path 28, and liquid storage section 22, and circulated through first filter 23. Therefore, even when using liquid with sedimentation, sedimentation can be reduced.

[0061] Change Example

[0062] This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined and implemented within the scope of technical inconsistency.

[0063] The supply mechanism 13 may also include a supply pump that supplies liquid from the liquid supply source 17 to the injection section 12. The supply pump may also be installed in the supply flow path 21 upstream of the supply chamber 34 in the liquid delivery direction D. Alternatively, the supply pump may be installed in the supply flow path 21 downstream of the supply chamber 34 in the liquid delivery direction D.

[0064] The pump 29 may also be installed in the supply flow path 21 between the first filter 23 and the branch 27 in the liquid delivery direction D. The liquid injection device 11 may also have a downstream valve installed in the supply flow path 21 or the injection section 12, which is located downstream of the branch 27 in the liquid delivery direction D. The pump 29 may also be driven with the downstream valve open to supply liquid to the nozzle 19. The pump 29 may also be driven with the downstream valve closed to allow liquid to flow from one end of the branch flow path 28 to the other end.

[0065] • Branch section 27 may also be provided on the spray section 12. Branch flow path 28 may also connect the spray section 12 and the liquid storage section 22. Pump 29 may also circulate the liquid in the supply chamber 34, the supply flow path 21 which is closer to the downstream of the liquid delivery direction D than the supply chamber 34, the spray section 12, the branch flow path 28 and the liquid storage section 22.

[0066] The mesh size of the second filter 26 can be the same as that of the first filter 23. The mesh size of the second filter 26 can also be coarser than that of the first filter 23. By making the mesh size of the second filter 26 coarser than that of the first filter 23, pressure loss can be reduced. The second filter 26 can also be located at the outlet where liquid flows out of the supply chamber 34. The second filter 26 can also trap and collect air bubbles, thus making it easier for bubbles to accumulate in the liquid storage section 22. The second filter 26 can also be located on the spray section 12.

[0067] The drive unit 25 can also move the first flexible membrane 38. For example, the drive unit 25 can reduce the pressure in the liquid storage section 22 by moving the first flexible membrane 38 from the first forward position to the first retracted position, thereby moving the air bubbles in the supply chamber 34 into the liquid storage section 22.

[0068] The liquid level detection sensor 30 may also include: a prism positioned at a predetermined location; an illumination section that illuminates the prism with light; and a light-receiving section that receives the light refracted by the prism. During contact between the liquid and the prism, the light diffuses into the liquid. When the gas-liquid interface 36 is located lower than the prism, and the prism is exposed from the liquid, the light refracted by the prism reaches the light-receiving section. The liquid level detection sensor 30 may also detect the position of the gas-liquid interface 36 based on changes in the amount of light received by the light-receiving section.

[0069] • The liquid level detection sensor 30 can also be a float sensor that detects the position of a float floating on the liquid.

[0070] The liquid level detection sensor 30 can also be an image sensor that detects images. The liquid level detection sensor 30 can also detect the position of the gas-liquid interface 36 by analyzing the image detected by the image sensor.

[0071] The liquid level detection sensor 30 can also be a photoelectric sensor comprising a light-emitting part that emits light and a light-receiving part that receives light. The light-emitting part and the light-receiving part can also be disposed with the liquid storage unit 22 sandwiched between them. The light-receiving part can also receive light transmitted through the liquid storage unit 22. For example, when the gas-liquid interface 36 is positioned higher than a predetermined position, the light is blocked by the liquid present between the light-emitting part and the light-receiving part. The liquid level detection sensor 30 can also detect the position of the gas-liquid interface 36 based on changes in the amount of light received by the light-receiving part.

[0072] The suction unit 40 can also be used for the maintenance of the spray unit 12. The suction unit 40 can also perform suction cleaning of the liquid discharged from the nozzle 19 by performing suction action. Suction cleaning is the maintenance of removing liquid with increased viscosity and air bubbles near the nozzle 19.

[0073] At least a portion of the first flexible membrane 38 may form a sidewall of the liquid storage section 22. A portion of the first flexible membrane 38 may also be located below the gas-liquid interface 36.

[0074] • The volume of the liquid storage section 22 may remain unchanged. The liquid storage section 22 may also be formed of a rigid component. The liquid storage section 22 may also be open to the atmosphere. That is, atmospheric pressure may also act on the gas-liquid interface 36. The adjustment mechanism 14 may also have, for example, a supply pump located upstream of the supply chamber 34 in the liquid delivery direction D, which supplies liquid to the supply chamber 34 to raise the gas-liquid interface 36 within the liquid storage section 22.

[0075] The adjusting mechanism 14 may also include a pressure reducing pump for depressurizing the liquid storage section 22. The adjusting mechanism 14 may also use the pressure reducing pump to depressurize the liquid storage section 22, thereby causing the gas-liquid interface 36 to rise.

[0076] A portion of the first filter 23 may also be located below the inlet that allows liquid to flow into the supply chamber 34. A portion of the first filter 23 may also be located below the outlet that allows liquid to flow out of the supply chamber 34.

[0077] The liquid storage unit 22 can also adjust the pressure of the supply flow path 21. When the pressure of the supply flow path 21 changes, the volume of air in the liquid storage unit 22 changes. As a result, the pressure change in the supply flow path 21 can be mitigated. The liquid storage unit 22 can also mitigate the pressure change in the supply flow path 21 by changing its volume through the movement of the first flexible membrane 38.

[0078] • The liquid jetting device 11 can also be a liquid jetting device that jets or sprays liquids other than ink. The state of the liquid ejected from the liquid jetting device as micro-droplets includes granular, tear-like, and filamentous tailing states. The liquid referred to here can be any material that can be jetted from the liquid jetting device. For example, the liquid can be any liquid in its liquid phase state, including liquids with high or low viscosity, sols, gel water, other inorganic solvents, organic solvents, solutions, liquid resins, liquid metals, and molten metals. The liquid includes not only liquids in a state of matter, but also liquids in which functional material particles composed of solid substances such as pigments or metal particles are dissolved, dispersed, or mixed in a solvent. Representative examples of liquids include inks or liquid crystals described in the above embodiments. Here, inks include general water-based inks, oil-based inks, and various liquid compositions such as gel inks and hot-melt inks. Specific examples of liquid jetting devices include those that jet liquids containing electrode materials or coloring materials used in the manufacture of liquid crystal displays, electroluminescent displays, surface-emitting displays, and color filters in a dispersed or dissolved form. Liquid jetting devices can also be used to jet organic substances from living organisms used in biochip manufacturing, as well as to jet liquid samples using precision pipettes, or as printing and dyeing devices or micro-dispensers. Liquid jetting devices can also be used to precisely jet lubricating oil into precision machinery such as watches or cameras, or to jet transparent resin liquids such as UV-curable resins onto substrates to form micro-hemispherical lenses or optical lenses used in optical communication components. Liquid jetting devices can also be used to jet etching solutions such as acids or alkalis to etch substrates.

[0079] Postscript

[0080] The following describes the technical concepts and effects learned based on the above-described implementation methods and modifications.

[0081] (A) A liquid injection device includes: an injection section capable of injecting liquid into a medium; a supply flow path capable of supplying the liquid to the injection section; a liquid storage section connected to the supply flow path capable of storing the liquid and forming a gas-liquid interface where the liquid and air are in contact; a first filter disposed below the gas-liquid interface and dividing the supply flow path and the liquid storage section; an adjustment mechanism capable of raising the height of the gas-liquid interface within the liquid storage section; and a control section controlling the adjustment mechanism.

[0082] According to this configuration, the first filter is divided into a supply flow path and a liquid storage section. An adjustment mechanism can adjust the height of the gas-liquid interface within the liquid storage section. Therefore, the control unit can adjust the gas-liquid interface to be positioned higher than the first filter by controlling the adjustment mechanism. That is, since the first filter can be maintained below the gas-liquid interface, the possibility of foreign matter generated at the gas-liquid interface flowing downstream of the liquid storage section can be reduced.

[0083] (B) Alternatively, in the liquid injection device, when the direction of the liquid flowing in the supply flow path is taken as the liquid delivery direction, the adjustment mechanism has: a valve section disposed on the supply flow path closer to the upstream side in the liquid delivery direction than the liquid storage section; and a suction section that performs a suction action to draw the liquid in the liquid storage section and cause the liquid to flow to the downstream side in the liquid delivery direction, wherein the control section performs a descending action to lower the gas-liquid interface by performing the suction action with the valve section closed, and opens the valve section when the gas-liquid interface is lowered to a position lower than the first filter by the descending action.

[0084] According to this configuration, the control unit closes the valve and performs a suction operation, causing the gas-liquid interface to drop below the first filter. As a result, the air and liquid in the liquid storage unit are sent downstream in the liquid delivery direction. Therefore, when the valve opens and liquid is supplied from upstream in the liquid delivery direction, the gas-liquid interface in the liquid storage unit rises from its original position. Thus, the gas-liquid interface can be raised with a simple configuration.

[0085] (C) Alternatively, in the liquid injection device, the adjustment mechanism has a first flexible membrane disposed above the gas-liquid interface, the first flexible membrane being movable to a first retracted position and a first forward position advancing towards the gas-liquid interface side compared to the first retracted position, thereby reducing the volume of the liquid storage section by advancing from the first retracted position to the first forward position with the descent action.

[0086] According to this configuration, the first flexible membrane moves from a first retracted position to a first forward position during the descent action, thereby reducing the volume of the liquid storage section. Therefore, the gas-liquid interface can be easily lowered by the descent action, and the gas-liquid interface can be easily raised by opening the valve section.

[0087] (D) Alternatively, the liquid injection device may be equipped with a liquid level detection sensor to detect that the position of the gas-liquid interface is at a predetermined position above the first filter. Based on the detection of the liquid level detection sensor, the control unit controls the adjustment mechanism to raise the gas-liquid interface when the gas-liquid interface drops to the predetermined position.

[0088] The gas-liquid interface, for example, descends as air increases within the liquid storage section. According to this configuration, when the gas-liquid interface descends to a predetermined position, the control unit controls the adjustment mechanism to raise the gas-liquid interface. This predetermined position is above the first filter. Therefore, it is possible to position the gas-liquid interface above the first filter.

[0089] (E) Alternatively, the liquid injection device may further include: a second flexible membrane disposed at a position lower than the first filter; and a drive unit capable of moving the second flexible membrane to a second retracted position and a second forward position that moves towards the first filter side compared to the second retracted position, wherein the drive unit moves the second flexible membrane from the second retracted position to the second forward position when the gas-liquid interface is positioned higher than the first filter, thereby reducing the volume of the supply flow path.

[0090] Sometimes, air bubbles in the supply flow path fail to pass through the first filter and remain below it. To address this, according to this configuration, the drive unit advances the second flexible membrane from a second retracted position to a second forward position, thereby reducing the volume of the supply flow path. This increases the pressure within the supply flow path, making it easier for air bubbles remaining below the first filter to pass through. Therefore, it is possible to easily collect the air bubbles into the liquid storage section.

[0091] (F) Alternatively, in the liquid injection device, when the direction of the liquid flowing in the supply flow path is taken as the liquid delivery direction, a second filter is provided on the supply flow path on the downstream side closer to the liquid delivery direction than the liquid storage section, and the mesh of the second filter is finer than that of the first filter.

[0092] According to this configuration, the second filter is installed in the supply flow path closer to the downstream side than the liquid storage section. The mesh size of the second filter is finer than that of the first filter. Therefore, even if foreign matter passes through the first filter, it can be captured and collected by the second filter.

[0093] (G) Alternatively, when the direction of the liquid flowing in the supply flow path is taken as the liquid delivery direction, the liquid injection device further includes: a branch flow path that separates from the supply flow path on a downstream side closer to the liquid delivery direction than the liquid storage unit; and a pump that causes the liquid to flow in the branch flow path, wherein when one side of the branch from the supply flow path is taken as one end side and the opposite side of the branch from the supply flow path is taken as another end side, the pump causes the liquid to flow from the one end side to the other end side, the other end side being connected to the liquid storage unit.

[0094] According to this configuration, the branch flow path connects the supply flow path and the liquid storage section, which are located closer to the downstream side than the liquid storage section. A pump circulates the liquid within the branch flow path. The liquid is delivered in the order of supply flow path, branch flow path, and liquid storage section, and circulated through a first filter. Therefore, even when using liquids prone to precipitation, precipitation can be reduced.

Claims

1. A liquid injection device, characterized in that, The liquid injection device includes: The jetting section is capable of spraying liquid onto the medium; A supply flow path is provided to supply the liquid to the jet section; A liquid storage unit, connected to the supply flow path, is capable of storing the liquid and forming a gas-liquid interface between the liquid and air; The first filter is located below the gas-liquid interface, dividing the supply flow path and the liquid storage section; The adjustment mechanism enables the height of the gas-liquid interface within the liquid storage section to be increased; and The control unit controls the adjustment mechanism. When the direction of the liquid flowing in the supply path is taken as the liquid delivery direction... The adjustment mechanism has: A valve section is disposed on the supply flow path on the upstream side of the liquid delivery direction, closer to the liquid storage section than the liquid storage section; and The suction unit performs a suction action to draw the liquid from the liquid storage unit and cause the liquid to flow downstream in the liquid delivery direction. The control unit performs a descent action to lower the gas-liquid interface by performing the suction action while the valve is closed, and opens the valve when the gas-liquid interface is lowered to a position below the first filter.

2. The liquid injection device according to claim 1, characterized in that, The adjustment mechanism includes: a first flexible membrane positioned above the gas-liquid interface. The first flexible membrane is capable of moving to a first retracted position and a first forward position that moves towards the gas-liquid interface side compared to the first retracted position. By moving from the first retracted position to the first forward position with the descent action, the volume of the liquid storage section is reduced.

3. The liquid injection device according to claim 1, characterized in that, The liquid injection device includes: a liquid level detection sensor, which detects that the position of the gas-liquid interface is at a predetermined position above the first filter. Based on the detection of the liquid level sensor, the control unit controls the adjustment mechanism to raise the gas-liquid interface when the gas-liquid interface drops to the predetermined position.

4. The liquid injection device according to claim 2, characterized in that, The liquid injection device also includes: The second flexible membrane is disposed below the first filter; and The drive unit is capable of moving the second flexible membrane to a second retracted position and a second advancing position that advances towards the first filter side compared to the second retracted position. When the gas-liquid interface is positioned above the first filter, the drive unit reduces the volume of the supply path by advancing the second flexible membrane from the second retracted position to the second forward position.

5. The liquid injection device according to claim 1, characterized in that, When the direction of the liquid flowing in the supply path is taken as the liquid delivery direction... The liquid injection device, located downstream of the liquid storage section in the liquid delivery direction, also includes a second filter disposed in the supply flow path. The mesh size of the second filter is finer than that of the first filter.

6. The liquid injection device according to claim 1, characterized in that, When the direction of the liquid flowing in the supply path is taken as the liquid delivery direction, the liquid injection device further comprises: A branch flow path, located downstream of the supply flow path closer to the liquid storage section in the liquid delivery direction; and The pump causes the liquid to flow within the branch flow path. When, in the branch flow path, one side of the branch from the supply flow path is taken as one end side, and the opposite side of the branch from the supply flow path is taken as the other end side, The pump causes the liquid to flow from one end to the other end. The other end is connected to the liquid storage section.

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