JP2020131439A - Liquid jet device, and method for controlling liquid jet device - Google Patents

Abstract

To provide a liquid jet device which can prevent pressure control is performed from getting complicated, and a method for controlling a liquid jet device.SOLUTION: A liquid jet device includes a liquid jet head 20 having a nozzle surface 21a to which a nozzle 21 is opened, a liquid supply path 30 that supplies a liquid to the liquid jet head 20, a liquid discharge path 40 that discharges the liquid from the liquid jet head 20, a supply side pressure control valve 31 that can control a pressure in a supply side liquid chamber 33 provided on the liquid supply path 30 to a first pressure of maintaining a gas-liquid interface formed on the nozzle 21, a liquid storage part 15 that is connected to the liquid discharge path 40, a third opening/closing valve 120 which is configured to act the pressure in the liquid storage part 15 on the nozzle 21 through the liquid discharge path 40 by being opened, and a control part that controls the third opening/closing valve 120, and makes a pressure in the liquid storage part 15 controlled to the second pressure that is lower than the first pressure and maintains a gas-liquid discharge path formed on the nozzle 21 act on the nozzle 21 through the liquid discharge path 40.SELECTED DRAWING: Figure 8

Description

The present invention relates to a liquid injection device such as a printer and a control method for the liquid injection device.

As an example of a liquid injection device, there is an inkjet printer that prints by ejecting ink, which is an example of liquid, from a nozzle that opens in a liquid injection head. In such a printer, when the ink is circulated, the pressure near the nozzle of the liquid injection head is set to an appropriate value so that the ink does not leak from the nozzle and air is not drawn from the nozzle. It is desirable to keep it.

For example, the printer of Patent Document 1 uses a preset calculation formula based on the pressure detected from the ink tanks connected to the liquid injection head and provided on the upstream side and the downstream side of the ink circulation system, respectively. It has a calculation means for obtaining pressure. Further, the printer of Patent Document 1 makes the value Y obtained by the calculation means compare with the reference value by the pressure determining means, and determines whether the pressure is positive or negative with respect to the reference value. Then, in the printer of Patent Document 1, a pump is connected to the ink circulation system, and when it is determined that the pressure is positive with respect to the reference value, the negative pressure value with respect to the nozzle is increased. As a result, the printer of Patent Document 1 can maintain an appropriate pressure in the vicinity of the nozzle of the liquid injection head when circulating the ink.

Japanese Unexamined Patent Publication No. 2013-107403

However, in such a printer, there is a problem that pressure control for maintaining an appropriate pressure in the vicinity of the nozzle of the liquid injection head becomes complicated when performing a circulation operation for circulating ink.

A liquid injection device that solves the above problems is a liquid that is connected to a liquid injection head having a nozzle surface through which a nozzle for injecting liquid opens and a liquid inlet of the liquid injection head to supply the liquid to the liquid injection head. A supply path, a liquid discharge path connected to the liquid outlet of the liquid injection head and discharging the liquid from the liquid injection head, and a supply side liquid chamber connected to the liquid outlet via the liquid supply path. When the pressure in the supply side liquid chamber becomes a first pressure lower than the pressure outside the supply side liquid chamber, the valve is opened to be upstream of the supply side liquid chamber and the supply side liquid chamber. A supply side having a supply side valve body communicating with the liquid supply path on the side and adjusting the pressure of the liquid supplied to the liquid injection head to a pressure at which a gas-liquid interface formed in the nozzle is maintained. A pressure adjusting valve, a liquid storage portion connected to the liquid discharge passage, a storage portion pressure adjusting mechanism configured so that the pressure in the liquid storage portion acts on the nozzle via the liquid discharge passage, and the above. The liquid in the liquid reservoir is adjusted to a second pressure that is lower than the first pressure and maintains the gas-liquid interface formed in the nozzle by controlling the reservoir pressure adjusting mechanism. A control unit that acts on the nozzle via the discharge path is provided.

A control method for a liquid injection device that solves the above problems is to connect a liquid injection head having a nozzle surface through which a nozzle for injecting a liquid opens and a liquid inlet of the liquid injection head to supply the liquid to the liquid injection head. A supply connected to the liquid supply path to be supplied, a liquid discharge path connected to the liquid outlet of the liquid injection head to discharge the liquid from the liquid injection head, and the liquid outlet via the liquid supply path. It has a side liquid chamber, and when the pressure in the supply side liquid chamber becomes a first pressure lower than the pressure outside the supply side liquid chamber, the valve is opened to open the supply side liquid chamber and the supply side liquid. It has a supply-side valve body that communicates with the liquid supply path on the upstream side of the chamber, and adjusts the pressure of the liquid supplied to the liquid injection head to a pressure that maintains the gas-liquid interface formed in the nozzle. A method for controlling a liquid injection device including a supply-side pressure adjusting valve and a liquid storage unit connected to the liquid discharge path, which is lower than the first pressure and is formed in the nozzle. The pressure in the liquid storage unit adjusted to a second pressure at which the interface is not broken is applied to the nozzle through the liquid discharge path, and the liquid in the liquid injection head is discharged to the liquid discharge path side. ..

Perspective view of the recording device. The schematic diagram which shows the structure of the liquid injection apparatus. The schematic diagram which shows the liquid injection head, the pressure adjustment valve of a supply side, and maintenance apparatus. FIG. 3 is a cross-sectional view taken along the line 4-4 in FIG. The block diagram which shows the electrical structure of a liquid injection device. A flowchart showing an example of cyclic processing. The flowchart which shows an example of a pressure cleaning process. The schematic diagram which shows the structure of the liquid injection apparatus in 2nd Embodiment. The schematic diagram which shows the structure of the liquid injection apparatus in 3rd Embodiment. FIG. 9 is a cross-sectional view taken along the line 10-10 in FIG. The schematic diagram which shows the supply side liquid storage part in 4th Embodiment. The schematic diagram which shows the structure of the liquid injection apparatus in 5th Embodiment.

(First Embodiment)
Hereinafter, the first embodiment of the recording device including the liquid injection device will be described with reference to the drawings.

As shown in FIG. 1, the recording device 11 includes a liquid injection device 11a, and has a substantially rectangular parallelepiped shape that is long in the vertical direction Z as a whole. The vertical direction Z is the direction of gravity. The liquid injection device 11a includes a liquid injection unit 12 capable of injecting ink, which is an example of a liquid. The liquid injection unit 12 records by injecting liquid onto the paper 14 transported along the transport path 13 indicated by the alternate long and short dash line in the figure. In the present embodiment, the liquid injection unit 12 is a so-called line head capable of simultaneously injecting ink in the width direction X of the paper 14. The width direction X is a direction along the transport region in which the paper 14 is transported and a direction intersecting (for example, orthogonal to) the transport direction Y of the paper 14. The transport region is a planar region along the transport path 13, and is a region through which the paper 14 transported by the transport unit passes.

As shown in FIG. 2, the liquid injection device 11a includes a liquid storage unit 15 capable of containing a liquid, a plurality of liquid injection heads 20 for injecting a liquid, and each liquid injection head for the liquid stored in the liquid storage unit 15. A liquid supply path 30 for supplying to 20 and a liquid discharge path 40 for discharging liquid from each liquid injection head 20 are provided. The liquid storage unit 15 may be a liquid tank capable of injecting liquid through an injection hole (not shown) while being attached to the recording device 11, or may be a liquid cartridge that can be attached to and detached from the recording device 11.

As shown in FIGS. 3 and 4, each liquid injection head 20 includes a nozzle surface 21a through which a plurality of nozzles 21 capable of injecting a liquid are opened. Each liquid injection head 20 includes a first common liquid chamber 22 to which a liquid is supplied. The liquid inflow port 22a connected to the liquid supply path 30 is opened in the first common liquid chamber 22. That is, the liquid supply path 30 is connected to the liquid inflow port 22a of each liquid injection head 20 to supply the liquid to each liquid injection head 20.

Each liquid injection head 20 includes a plurality of injection liquid chambers 23 that communicate with the first common liquid chamber 22 via the first continuous passage 22b shown in FIG. The plurality of nozzles 21 are provided corresponding to the plurality of injection liquid chambers 23. Each injection liquid chamber 23 communicates with the first common liquid chamber 22 and the nozzle 21. A part of the wall surface of each injection liquid chamber 23 is formed by the diaphragm 24.

Each liquid injection head 20 includes a plurality of actuators 25 corresponding to the plurality of injection liquid chambers 23. Each actuator 25 is provided on the surface of the diaphragm 24 opposite to the portion facing each injection liquid chamber 23. Each actuator 25 is housed in a storage chamber 26 arranged at a position different from that of the first common liquid chamber 22. Each liquid injection head 20 discharges the liquid in each injection liquid chamber 23 as droplets from each nozzle 21 by driving each actuator 25.

As an example, each actuator 25 of the present embodiment may be configured by a piezoelectric element that contracts when a driving voltage is applied. In this case, when the diaphragm 24 is deformed due to the contraction of each actuator 25 due to the application of the drive voltage and then the application of the drive voltage to each actuator 25 is released, the liquid in each injection liquid chamber 23 whose volume has changed. Is ejected as droplets from each nozzle 21.

Each liquid injection head 20 has a second common liquid chamber 27 that communicates with each injection liquid chamber 23 via the second continuous passage 27b shown in FIG. The liquid outlet 27a connected to the liquid discharge path 40 is opened in the second common liquid chamber 27. That is, the liquid discharge path 40 is connected to the liquid outlet 27a of each liquid injection head 20 and discharges the liquid from each liquid injection head 20.

As shown in FIG. 2, the liquid injection device 11a has a return flow path 50 that connects the liquid discharge path 40 and the liquid storage portion 15, and a first on-off valve that closes the return flow path 50 when the valve is closed. A 51 and a flow pump 52 as an example of a flow mechanism for flowing a liquid are provided. The flow pump 52 is provided on the liquid storage portion 15 side of the return flow path 50 with respect to the first on-off valve 51.

The liquid supply path 30 is provided with a degassing section 60 capable of degassing the liquid in the liquid supply path 30. The degassing unit 60 may include, for example, a cylindrical hollow fiber membrane 61 forming a part of the liquid supply path 30, and a decompression mechanism 62 for depressurizing the liquid in the liquid supply path 30 for degassing. it can. In this case, the decompression mechanism 62 includes a decompression chamber 63 for accommodating the hollow fiber membrane 61, a gas flow path 64 connected to the decompression chamber, and a vacuum pump 65 for decompressing the decompression chamber 63. When the vacuum pump 65 decompresses the pressure reducing chamber 63, the space outside the hollow fiber membrane 61 is depressurized, and the gas dissolved in the liquid inside the hollow fiber membrane 61 is sucked to the outside of the hollow fiber membrane 61. As a result, the liquid inside the hollow fiber membrane 61 is degassed.

In the liquid supply path 30, between the degassing unit 60 and each liquid injection head 20, a plurality of supply side pressures, which is an example of a supply side pressure adjusting mechanism for adjusting the pressure of the liquid supplied to each liquid injection head 20. A regulating valve 31 is provided.

As shown in FIG. 3, the supply-side pressure adjusting valve 31 includes a supply-side liquid chamber 33 whose volume is changed by bending the supply-side flexible portion 32 constituting the wall portion, and a supply-side liquid chamber 33. The supply side communication chamber 34 that communicates, the supply side valve body 35 that can shut off the supply side liquid chamber 33 and the supply side communication chamber 34, and the supply side urging that urges the supply side valve body 35 in the closing direction. A member 36 is provided. The supply-side liquid chamber 33 of each supply-side pressure adjusting valve 31 can communicate with the degassing unit 60 through the liquid supply passage 30. Further, the supply side communication chamber 34 of each supply side pressure adjusting valve 31 communicates with the first common liquid chamber 22 of each liquid injection head 20 through the liquid supply passage 30.

In each supply-side pressure adjusting valve 31, a portion where the cross-sectional area of the flow path is expanded, such as the supply-side liquid chamber 33 and the supply-side communication chamber 34, and a portion having a complicated shape, such as the supply-side urging member 36. Foreign matter such as air bubbles tends to collect in such places. Therefore, in the present embodiment, filters 37a and 37b are provided at the inlet of each supply side pressure adjusting valve 31 and the inside of each supply side pressure adjusting valve 31 in order to capture foreign matter such as air bubbles. The number and arrangement of the filters 37a and 37b can be arbitrarily changed, and the installation of the filters 37a and 37b can be omitted.

As shown in FIG. 2, a discharge side pressure adjusting valve 41 for adjusting the pressure of the liquid supplied to the liquid injection head 20 is provided at a position where the liquid discharge path 40 and the return flow path 50 are connected. .. The discharge side pressure adjusting valve 41 is provided through a discharge side liquid chamber 43 whose volume is changed by bending the discharge side flexible portion 42 constituting the wall portion, a discharge side liquid chamber 43, and a first communication hole 43a. It has a first discharge side communication room 44 that communicates with the first discharge side communication room 44, and a second discharge side communication room 45 that communicates with the first discharge side communication room 44. Further, the discharge side pressure adjusting valve 41 urges the discharge side valve body 46 capable of shutting off the discharge side liquid chamber 43 and the first discharge side communication chamber 44 and the discharge side valve body 46 in the closing direction. It has a side urging member 47.

The discharge side liquid chamber 43 communicates with the liquid discharge passage 40 through the second communication hole 43b. That is, the discharge side liquid chamber 43 is connected to the liquid outlet 27a via the liquid discharge path 40. In other words, the liquid discharge path 40 connects the discharge side liquid chamber 43 and the liquid outlet 27a of the second common liquid chamber 27. Further, the discharge side liquid chamber 43 communicates with the return flow path 50 through the third communication hole 43c. In other words, the return flow path 50 connects the discharge side liquid chamber 43 and the flow pump 52. That is, the flow pump 52 can discharge the liquid in each liquid injection head 20 to the liquid discharge path 40 side via the discharge side liquid chamber 43. Further, the discharge side liquid chamber 43 can communicate with the liquid storage portion 15 through the return flow path 50.

The liquid injection device 11a has a fluid introduction path 70 that communicates with the second discharge side communication chamber 45 and introduces the fluid into the second discharge side communication chamber 45. The fluid introduction path 70 is connected to an atmospheric communication passage 72 capable of introducing the atmosphere, which is an example of gas, via the first switching valve 71. Further, the fluid introduction path 70 is connected to the bypass flow path 73 capable of introducing the liquid from the liquid supply path 30 via the first switching valve 71. The first switching valve 71 is configured to be able to switch between a state in which the fluid introduction path 70 and the atmospheric communication passage 72 communicate with each other and a state in which the fluid introduction path 70 and the bypass flow path 73 communicate with each other. As an example, the first switching valve 71 is a three-way valve including three valve bodies capable of individually closing the three flow paths of the fluid introduction path 70, the atmospheric communication passage 72, and the bypass flow path 73. be able to.

One end of the atmospheric communication passage 72 communicates with the fluid introduction path 70, and the other end is opened to the atmosphere so that the atmosphere can be introduced into the second discharge side communication chamber 45 via the fluid introduction path 70. Has been done. In other words, the fluid introduction path 70 is configured so that air can be introduced into the discharge side liquid chamber 43 via the second discharge side communication chamber 45 and the first discharge side communication chamber 44. One end of the bypass flow path 73 communicates with the fluid introduction path 70, and the other end is connected between the degassing portion 60 in the liquid supply path 30 and the supply side pressure adjusting valve 31, so that the fluid introduction path 70 is connected. The liquid can be introduced into the second discharge side communication chamber 45 via the above. That is, the fluid introduction path 70 is connected to the discharge side liquid chamber 43 via the second discharge side communication chamber 45 and the first discharge side communication chamber 44, and of the liquid supply path 30 via the bypass flow path 73. It is connected to the upstream side liquid supply path 30a which is on the upstream side of the supply side liquid chamber 33. In other words, the fluid introduction passage 70 is configured so that the liquid can be introduced into the discharge side liquid chamber 43 by connecting the discharge side liquid chamber 43 and the upstream side liquid supply passage 30a.

The liquid injection device 11a has an upstream liquid flow path from the degassing unit 60 toward the first common liquid chamber 22 of each liquid injection head 20 at the connection portion between the bypass flow path 73 and the upstream side liquid supply path 30a. It is preferable to provide a second switching valve 74 that can be switched between the supply path 30a and the bypass flow path 73. As an example, the second switching valve 74 connects the bypass flow path 73, the upstream side of the connection portion between the bypass flow path 73 in the upstream liquid supply path 30a, and the bypass flow path 73 in the upstream liquid supply path 30a. It can be a three-way valve provided with three valve bodies capable of individually closing the three flow paths on the downstream side of the portion. The liquid injection device 11a may include only one of the atmospheric communication passage 72 and the bypass passage 73. That is, the fluid introduction passage 70 may be communicated with either the atmospheric communication passage 72 or the bypass passage 73.

In the discharge side liquid chamber 43, the second communication hole 43b is opened below the first communication hole 43a in the vertical direction Z. In other words, the liquid discharge passage 40 opens to the discharge side liquid chamber 43 at a position below the position where the fluid flowing in from the fluid introduction passage 70 flows into the discharge side liquid chamber 43.

Further, in the discharge side liquid chamber 43, the third communication hole 43c is opened above the first communication hole 43a in the vertical direction Z. In other words, the return flow path 50 opens into the discharge side liquid chamber 43 at a position above the position where the fluid flowing in from the fluid introduction path 70 flows into the discharge side liquid chamber 43.

In the liquid supply path 30, it is preferable to provide a temporary storage unit 80 for temporarily storing the degassed liquid by the degassing unit 60 between the degassing unit 60 and the second switching valve 74. Further, in the liquid supply path 30, a pressurizing pump 81 is provided between the degassing section 60 and the liquid accommodating section 15 to supply the liquid in a pressurized state from the degassing section 60 toward each liquid injection head 20. Is preferable.

The pressurizing pump 81 can function as a liquid flow unit for flowing the liquid in the liquid supply path 30. That is, since the liquid in the liquid supply path 30 is decompressed in the degassing unit 60, each liquid is stored in the temporary storage unit 80 in a state where the degassed liquid is pressurized by the pressurizing pump 81. It becomes possible to efficiently supply the liquid toward the injection head 20.

In the liquid supply path 30, the degassing unit 60 and the temporary storage unit 80 allow the liquid to flow from the degassing unit 60 to the temporary storage unit 80, while the degassing unit 80 to the temporary storage unit 80. It is preferable to provide a one-way valve 82 that regulates the flow of the liquid to 60. This is because the backflow of the liquid from the temporary storage unit 80, which is in a positive pressure state by pressurization, to the degassing unit 60, which is in a negative pressure state by decompression, is suppressed.

Further, a flexible storage bag is adopted as the temporary storage unit 80, and the temporary storage unit 80 composed of such a storage bag is housed in the pressurizing chamber 83 and pulled by the vacuum pump 65 for decompression. The gas may be introduced into the pressurizing chamber 83 through the gas flow path 64. In this case, by driving the vacuum pump 65 to introduce the gas into the pressurizing chamber 83, the liquid inside thereof can be pressurized through the storage bag.

In the case of adopting this configuration, if the first three-way valve 84 is arranged on the upstream side of the vacuum pump 65 and the second three-way valve 85 is arranged on the downstream side in the gas flow path 64, the pressure reducing chamber 63 The timing of depressurizing and the timing of pressurizing the pressurizing chamber 83 can be arbitrarily set.

That is, when the depressurization of the pressure reducing chamber 63 and the pressurization of the pressurizing chamber 83 are performed at the same time, they communicate with the outside of the first valve 84a and the second three-way valve 85 communicating with the outside of the first three-way valve 84. By closing the second valve 85a and driving the vacuum pump 65, the gas in the pressure reducing chamber 63 may be introduced into the pressurizing chamber 83. When the pressure reducing chamber 63 is depressurized independently, the gas drawn from the decompression chamber 63 is removed by closing the first valve 84a and opening the second valve 85a to drive the vacuum pump 65. It may be discharged to the outside. When pressurizing the pressurizing chamber 83 independently, the first valve 84a is opened and the second valve 85a is closed to drive the vacuum pump 65, thereby causing an external gas to flow. It may be taken into the road 64 and introduced into the pressurizing chamber 83.

In the liquid supply path 30, between the degassing section 60 and the liquid supply path 30, a foreign substance trapping section for trapping foreign substances such as air bubbles and dust mixed in the liquid and solidified solute components dissolved in the liquid is provided. Is preferable. The foreign matter trapping unit may be, for example, a filter 86 for filtering the liquid, an air trap 87 for trapping air bubbles mixed in the liquid, or a foreign matter having a high possibility of being mixed. These may be used in combination.

When the air trap 87 has a gas-liquid separation unit 87a capable of separating gas and liquid, a discharge pump 88 for flowing the liquid from the liquid supply path 30 toward the gas-liquid separation unit 87a and a valve closure. It is preferable to include a second on-off valve 89 that closes the liquid supply path 30 on the liquid storage portion 15 side of the discharge pump 88 when the state is reached.

The liquid injection device 11a includes a head holder 90 that holds each liquid injection head 20. The head holder 90 holds each liquid injection head 20 in a state where the nozzle surface 21a of each liquid injection head 20 faces downward in the vertical direction Z and is exposed. Further, the head holder 90 holds each supply side pressure adjustment valve 31 and discharge side pressure adjustment valve 41. The head holder 90 is configured to be displaceable along the vertical direction Z by driving a drive unit (not shown). Each liquid injection head 20, each supply side pressure adjusting valve 31, and discharging side pressure adjusting valve 41 do not move relative to the head holder 90. That is, each liquid injection head 20, each supply side pressure adjusting valve 31, and each discharging side pressure adjusting valve 41 move with the movement of the head holder 90. Further, each liquid injection head 20, each supply side pressure adjusting valve 31, and each discharging side pressure adjusting valve 41 are held in the head holder 90 in a state where they do not move relative to each other.

As shown in FIG. 3, the liquid injection device 11a includes a maintenance device 100 for performing maintenance of each liquid injection head 20. The maintenance device 100 includes a cap 101 that forms a closed space in which the nozzle 21 provided in each liquid injection head 20 opens, a suction mechanism 102, and a wiper unit 103.

The cap 101 is configured to be able to form a closed space by contacting the nozzle surface 21a of each liquid injection head 20. In the following description, capping means that the cap 101 contacts the nozzle surface 21a of each liquid injection head 20 to form a closed space. Capping can be performed by moving each liquid injection head 20 in a direction approaching the cap 101, or by moving the cap 101 in a direction approaching each liquid injection head 20. Further, the object that the cap 101 comes into contact with during capping is not limited to the nozzle surface 21a. For example, by contacting the side surface portion of each liquid injection head 20 or the head holder 90 holding each liquid injection head 20 with the cap 101, the nozzle It is also possible to form a closed space in which 21 opens. The cap 101 is provided with a cap opening valve 101a for opening the closed space to the atmosphere.

The suction mechanism 102 includes a waste liquid tank 102a, a waste liquid flow path 102b that connects the waste liquid tank 102a and the cap 101, and a pressure reducing pump 102c that is arranged at an intermediate position of the waste liquid flow path 102b. The wiper unit 103 includes a wiper 103a that wipes the nozzle surface 21a and a moving body 103b that holds and moves the wiper 103a.

Further, as shown in FIG. 5, the liquid injection device 11a includes a control unit 200 that controls the components constituting the liquid injection device 11a. The control unit 200 controls each liquid injection head 20, a flow pump 52, a vacuum pump 65, a pressure pump 81, a discharge pump 88, and a pressure reducing pump 102c. Further, the control unit 200 includes a first on-off valve 51, a second on-off valve 89, a first switching valve 71, a second switching valve 74, a first three-way valve 84, a second three-way valve 85, and a cap opening valve 101a. And the moving body 103b is controlled. The control unit 200 may be provided with a plurality of those that individually control the components, or may be provided with a device that comprehensively controls the plurality of components.

The liquid injection device 11a closes the first on-off valve 51 and the cap release valve 101a under the control of the control unit 200, and the second switching valve 74 switches the liquid flow path to the liquid supply path 30. It is in the normal state. Further, in the normal state, the control unit 200 caps each liquid injection head 20 with the cap 101 to suppress the drying of the nozzle 21.

When the liquid injection device 11a is activated, the discharge pump 88 and the pressure pump 81 are driven and controlled by the control unit 200 so that the inside of the temporary storage unit 80 is maintained at a predetermined positive pressure (pressurized state). .. As a result, in the normal state, the temporary storage unit 80, the supply side communication chamber 34 of each supply side pressure adjusting valve 31, and the liquid supply passage 30 between the temporary storage unit 80 and the supply side communication chamber 34 are added to a predetermined position. It is held in a pressure state. Further, the control unit 200 depressurizes the depressurizing chamber 63 by controlling the vacuum pump 65, the first three-way valve 84, and the second three-way valve 85 according to the drive of the pressurizing pump 81, and has been degassed. Liquid is sent to the temporary storage unit 80.

Even if the liquid in the supply side communication chamber 34 of each supply side pressure adjustment valve 31 is in a pressurized state, the supply side valve body 35 in each supply side pressure adjustment valve 31 is affected by the urging force of the supply side urging member 36. While the state in which the supply side liquid chamber 33 and the supply side communication chamber 34 are shut off is maintained, the liquid does not flow from the supply side communication chamber 34 to the supply side liquid chamber 33.

Here, each supply side pressure adjusting valve 31 and discharge side pressure adjusting valve 41 of the present embodiment will be described in detail.
As shown in FIG. 3, the supply-side flexible portion 32 of each supply-side pressure regulating valve 31 receives the pressure of the liquid in the supply-side liquid chamber 33 on the supply-side inner surface 32a, which is the inner surface of the supply-side liquid chamber 33. The supply-side flexible portion 32 receives atmospheric pressure on the supply-side outer surface 32b, which is the outer surface of the supply-side liquid chamber 33. Therefore, the supply-side flexible portion 32 of each supply-side pressure adjusting valve 31 bends when the pressure in the supply-side liquid chamber 33 fluctuates. In an example of this embodiment, the pressure in the supply-side liquid chamber 33 refers to the pressure applied to the central portion of the supply-side flexible portion 32.

The supply-side flexible portion 32 bends when the amount of liquid in the supply-side liquid chamber 33 changes, so that the center of the supply-side flexible portion 32 is displaced and the volume of the supply-side liquid chamber 33 changes. When the amount of liquid in the supply side liquid chamber 33 decreases due to the discharge of the liquid from the supply side liquid chamber 33, the pressure in the supply side liquid chamber 33 decreases, so that the supply side flexible portion 32 becomes It bends in the direction of reducing the volume of the liquid chamber 33 on the supply side. Further, when the amount of liquid in the supply side liquid chamber 33 increases due to the inflow of liquid into the supply side liquid chamber 33, the pressure in the supply side liquid chamber 33 rises, so that the supply side flexible portion 32 becomes , It bends in the direction of increasing the volume of the liquid chamber 33 on the supply side.

In each supply-side pressure adjusting valve 31, the supply-side valve body 35 is connected to the supply-side inner surface 32a of the supply-side flexible portion 32. The supply side valve body 35 of each supply side pressure adjusting valve 31 moves according to the displacement of the supply side inner surface 32a. The supply-side valve body 35 of each supply-side pressure adjusting valve 31 opens when the supply-side flexible portion 32 is displaced in the direction of reducing the volume of the supply-side liquid chamber 33, and supplies the supply-side liquid chamber 33 with the supply-side liquid chamber 33. It communicates with the side communication room 34. Further, the supply side valve body 35 of each supply side pressure adjusting valve 31 is closed when the supply side flexible portion 32 is displaced in the direction of increasing the volume of the supply side liquid chamber 33, and the supply side liquid chamber 33 is closed. And the supply side communication room 34 are cut off.

In each supply-side pressure adjusting valve 31, the supply-side urging member 36 urges the supply-side valve body 35 in the direction of closing the valve. In each supply-side pressure adjusting valve 31, the supply-side valve body 35 has a first pressure (for example, in FIG. 2), which is lower than the atmospheric pressure at which the pressure inside the supply-side liquid chamber 33 is the pressure outside the supply-side liquid chamber 33. When the pressure becomes −500 Pa to −1000 Pa) with respect to the atmospheric pressure, the valve is opened to communicate the supply side liquid chamber 33 and the supply side communication chamber 34. The first pressure is the pressing force of the supply side urging member 36, the force required to displace the supply side flexible portion 32, and the supply side liquid chamber 33 and the supply side communication chamber 34 by the supply side valve body 35. It is determined according to the seal load which is a pressing force required for shutting off, the pressure in the supply side communication chamber 34 acting on the surface of the supply side valve body 35, and the pressure in the supply side liquid chamber 33. That is, the larger the pressing force of the supply side urging member 36, the lower the first pressure for changing from the valve closed state to the valve open state. That is, the first pressure can be set by determining the pressing force of the supply side urging member 36.

The first pressure is set to the pressure in the supply-side liquid chamber 33 that can maintain the gas-liquid interface formed in the nozzle 21 of each liquid injection head 20. In this case, the gas-liquid interface is the boundary where the liquid and the gas come into contact with each other. The pressure capable of maintaining the gas-liquid interface formed in the nozzle 21 (for example, +500 Pa to -3500 Pa with respect to the atmospheric pressure) is, in other words, a pressure capable of forming a meniscus at the gas-liquid interface in the nozzle 21. The meniscus is a curved liquid surface formed by contacting the liquid with the nozzle 21. It is preferable that the nozzle 21 is formed with a concave meniscus suitable for ejecting droplets. The difference between the pressure applied to the gas-liquid interface formed on the nozzle 21 and the pressure in the supply-side liquid chamber 33 depends on the distance D1 between the position of the nozzle surface 21a in the vertical direction Z and the center position of the supply-side flexible portion 32. Change. Therefore, the first pressure is set in consideration of the distance D1 (for example, 50 mm in FIG. 2) between the position of the nozzle surface 21a in the vertical direction Z and the center position of the supply-side flexible portion 32. In the following description, the pressure applied to the gas-liquid interface formed on the nozzle 21 is referred to as the pressure applied to the nozzle 21.

In each supply-side pressure adjusting valve 31, when the pressure in the supply-side liquid chamber 33 becomes the first pressure, the supply-side valve body 35 opens to liquid from the supply-side communication chamber 34 to the supply-side liquid chamber 33. Inflows. That is, each supply-side pressure adjusting valve 31 can adjust the pressure in the supply-side liquid chamber 33 to the first pressure at which the gas-liquid interface formed in the nozzle 21 is maintained. In other words, each supply side pressure adjusting valve 31 adjusts the pressure of the liquid supplied to each liquid injection head 20 to a pressure at which the gas-liquid interface formed in the nozzle 21 is maintained.

As shown in FIG. 2, the discharge side flexible portion 42 of the discharge side pressure adjusting valve 41 receives the pressure of the liquid in the discharge side liquid chamber 43 on the discharge side inner surface 42a which is the inner surface of the discharge side liquid chamber 43. The discharge-side flexible portion 42 receives atmospheric pressure on the discharge-side outer surface 42b, which is the outer surface of the discharge-side liquid chamber 43. Therefore, the discharge-side flexible portion 42 bends when the pressure in the discharge-side liquid chamber 43 fluctuates. In an example of this embodiment, the pressure in the discharge side liquid chamber 43 refers to the pressure applied to the central portion of the discharge side flexible portion 42.

The discharge-side flexible portion 42 bends when the amount of liquid in the discharge-side liquid chamber 43 changes, so that the center of the discharge-side flexible portion 42 is displaced and the volume of the discharge-side liquid chamber 43 is changed. When the amount of liquid in the discharge side liquid chamber 43 decreases due to the discharge of the liquid from the discharge side liquid chamber 43, the pressure in the discharge side liquid chamber 43 decreases, so that the discharge side flexible portion 42 becomes. It bends in the direction of reducing the volume of the discharge side liquid chamber 43. Further, when the amount of liquid in the discharge side liquid chamber 43 increases due to the inflow of liquid into the discharge side liquid chamber 43, the pressure in the discharge side liquid chamber 43 rises, so that the discharge side flexible portion 42 , It bends in the direction of increasing the volume of the discharge side liquid chamber 43.

The discharge side valve body 46 is arranged so as to be in contact with the discharge side inner surface 42a of the discharge side flexible portion 42. The discharge side valve body 46 moves in contact with the discharge side inner surface 42a according to the displacement of the discharge side inner surface 42a. The discharge side valve body 46 is opened when the volume of the discharge side liquid chamber 43 is displaced in a direction of reducing the volume, so that the discharge side liquid chamber 43 and the first discharge side communication chamber 44 communicate with each other. The discharge side valve body 46 is closed when the discharge side flexible portion 42 is displaced in the direction of increasing the volume of the discharge side liquid chamber 43, and the discharge side liquid chamber 43 and the first discharge side communication chamber 44 are separated from each other. Cut off.

The discharge side urging member 47 urges the discharge side valve body 46 in the direction of closing the valve. In the discharge side valve body 46, the pressure inside the discharge side liquid chamber 43 is lower than the pressure outside the discharge side liquid chamber 43 and the first pressure (for example, in FIG. 2, -1000 Pa to atmospheric pressure in FIG. 2). When it reaches -3500 Pa), the valve is opened to communicate the discharge side liquid chamber 43 and the first discharge side communication chamber 44. The second pressure is the pressing force of the discharge side urging member 47, the force required to displace the discharge side flexible portion 42, and the discharge side valve body 46, so that the discharge side liquid chamber 43 and the first discharge side communication chamber 44 It is determined according to the seal load, which is a pressing force required to shut off the above, the pressure in the first discharge side communication chamber 44 acting on the surface of the discharge side valve body 46, and the pressure in the discharge side liquid chamber 43. That is, the larger the pressing force of the discharge side urging member 47, the lower the second pressure for changing from the valve closed state to the valve open state. That is, the second pressure can be set by determining the pressing force of the discharge side urging member 47.

The second pressure is a pressure in the discharge side liquid chamber 43 that can maintain the gas-liquid interface formed in the nozzle 21, and is set to a pressure lower than the first pressure. The difference between the pressure applied to the nozzle 21 and the pressure in the discharge side liquid chamber 43 changes depending on the distance D2 between the position of the nozzle surface 21a in the vertical direction Z and the center position of the discharge side flexible portion 42. Therefore, the second pressure is set in consideration of the distance D2 between the position of the nozzle surface 21a in the vertical direction Z and the center position of the discharge side flexible portion 42 (for example, 50 mm, which is the same as D1 in FIG. 2). ..

In an example of this embodiment, the center position of the discharge side flexible portion 42 coincides with the center position of the supply side flexible portion 32 in the vertical direction Z. That is, in an example of this embodiment, the distance D1 coincides with the distance D2.

In the discharge side pressure adjusting valve 41, when the pressure in the discharge side liquid chamber 43 becomes the first pressure, the discharge side valve body 46 opens and moves from the first discharge side communication chamber 44 to the discharge side liquid chamber 43. Liquid flows in. That is, the discharge side pressure adjusting valve 41 can adjust the pressure in the discharge side liquid chamber 43 to a second pressure at which the gas-liquid interface formed in the nozzle 21 is maintained. In other words, the discharge side pressure adjusting valve 41 adjusts the pressure of the liquid supplied to each liquid injection head 20 to a pressure at which the gas-liquid interface formed in the nozzle 21 is maintained.

In an example of this embodiment, the discharge side flexible portion 42 has a larger area than the supply side flexible portion 32. Therefore, the volume of the discharge side liquid chamber 43 that can be changed by the discharge side flexible portion 42 is larger than the volume of the supply side liquid chamber 33 that can be changed by the supply side flexible portion 32.

Next, the flow path resistance when the liquid is supplied from each supply side pressure adjusting valve 31 to each liquid injection head 20 and discharged from each liquid supply head to the discharge side pressure adjusting valve 41 will be described. In the following description, the direction in which the liquid flows from the supply side pressure adjusting valve 31 to the discharge side pressure adjusting valve 41 via each liquid injection head 20 is referred to as a flow path direction.

As shown in FIG. 4, the second flow path R2 between the nozzle 21 and the discharge side liquid chamber 43 extends from the supply side liquid chamber 33 of each supply side pressure adjusting valve 31 to the nozzle 21 of each liquid injection head 20. The flow path resistance is smaller than that of the first flow path R1 in between. The flow path resistance decreases when the cross section of the flow path is increased when cut in a plane orthogonal to the flow path direction, while the flow path breaks when cut in a plane orthogonal to the flow path direction. It increases when the area is reduced. Further, the flow path resistance decreases when the length of the flow path in the flow path direction is shortened, while increases when the length of the flow path in the flow path direction is increased.

Here, when the circulation operation is performed when the liquid is not injected from the nozzle 21 of the liquid injection head 20, the flow rate of the liquid flowing through the first flow path R1 and the second flow path R2 is Qm (m ³ / s). The first pressure is P1 (Pa), the second pressure is P2 (Pa), the pressure at the nozzle 21 is Pn (Pa), and the flow path resistance of the first flow path R1 is Ru (Pa · s / m ³ ). Assuming that the flow path resistance of the second flow path R2 is Rd (Pa · s / m ³ ),
P1-P2 = (Ru + Rd) * Qm
Pn-P2 = Rd * Qm → Pn = P2 + Rd * Qm
Further, when the circulation operation is performed while the liquid is being injected from the nozzle 21 of the liquid injection head 20, the flow rate of the liquid flowing through the second flow path R2 is Qj (m ³ / s), and the liquid injected from the nozzle 21. If the flow rate of is U (m ³ / s),
P1-P2 = Ru * (U + Qj) + Rd * Qj
Pn-P2 = Rd * Qj → Pn = P2 + Rd * Qj
In either case, in order to maintain the liquid pressure in the nozzle 21 with high accuracy, it is better that the difference between the liquid pressure Pn in the nozzle and the second pressure P2 is small, so that the flow in the second flow path R2 It is preferable to set the road resistance so that Rd is small.

In one example of the present embodiment, the cross-sectional area of the first flow path R1 when the liquid supply path 30 is cut by a plane orthogonal to the flow path direction is the flow path direction of the liquid discharge path 40 of the second flow path R2. It is smaller than the cross section when cut in a plane orthogonal to. Therefore, the flow path resistance of the liquid discharge path 40 between each liquid injection head 20 and the discharge side pressure adjusting valve 41 is the flow path resistance of the liquid supply path 30 between the supply side pressure adjusting valve 31 and each liquid injection head 20. It is smaller than the flow path resistance.

Further, in an example of the present embodiment, the cross-sectional area of the second flow path R2 when cut in a plane orthogonal to the flow path direction in the second common liquid chamber 27 is the first common liquid in the first flow path R1. It is larger than the cross-sectional area when cut in a plane orthogonal to the flow path direction in the chamber 22. Therefore, the flow path resistance between the second passage 27b and the liquid outlet 27a in the second common liquid chamber 27 is between the liquid inlet 22a and the first passage 22b in the first common liquid chamber 22. It is smaller than the flow path resistance.

On the other hand, in an example of the present embodiment, the length of the flow path in the flow path direction of the second communication passage 27b of the second flow path R2 is the flow path direction of the first communication passage 22b of the first flow path R1. Longer than the length of the flow path in. Therefore, the flow path resistance of the second passage 27b is larger than the flow path resistance of the first passage 22b.

In an example of the present embodiment, the first passage 22b and the second passage 27b are the first passage within a range in which the flow resistance in the second flow path R2 is smaller than the flow resistance in the first flow path R1. The flow path resistance of the 22b is configured to be smaller than the flow path resistance of the second passage 27b. In order to configure in this way, regarding the first flow path R1 and the second flow path R2, the flow path resistance in the liquid supply path 30 and the first common liquid chamber 22 of the first flow path R1 and the second flow. The difference between the flow path resistance in the liquid discharge path 40 and the second common liquid chamber 27 in the path R2 is larger than the difference between the flow path resistance in the first continuous passage 22b and the second continuous passage 27b. It may be configured as.

Next, a maintenance operation for maintaining the liquid injection device 11a and various processes executed by the control unit 200 will be described.
The liquid injection device 11a can execute a circulation operation for circulating the liquid in the liquid injection device 11a as a maintenance operation. In the liquid injection device 11a, when the flow of the liquid is stagnant, the liquid tends to thicken or bubbles tend to accumulate. In this case, since the states of the nozzle 21 and the injection liquid chamber 23 are not normal, the liquid ejection failure by the nozzle 21 is likely to occur. Therefore, the liquid injection device 11a is configured to execute a circulation operation for circulating the liquid in the liquid injection device 11a. Hereinafter, the cyclic processing for performing the cyclic operation will be described.

As shown in FIG. 6, in step S11, the control unit 200 opens the first on-off valve 51 to communicate the flow pump 52 and the discharge side liquid chamber 43. Subsequently, in step S12, the control unit 200 drives the flow pump 52 to discharge the liquid in the discharge side liquid chamber 43 to the return flow path 50 side. That is, the control unit 200 starts depressurizing the discharge side liquid chamber 43 in step S12. As a result, the control unit 200 circulates the liquid in the liquid injection device 11a. The flow of the liquid when the liquid in the liquid injection device 11a circulates will be described in detail later.

Subsequently, the control unit 200 stops driving the flow pump 52 in step S13. That is, the control unit 200 stops the depressurization of the discharge side liquid chamber 43 in step S13. After that, in step S14, the control unit 200 closes the first on-off valve 51 and ends the circulation process.

Here, the flow of the liquid in the circulation operation will be described.
As shown in FIG. 2, when the pressure in the discharge side liquid chamber 43 is higher than the second pressure, the discharge side valve body 46 does not open, and the discharge side liquid chamber 43 and the first discharge side communication chamber 43 do not open. 44 is cut off. Therefore, when the discharge side liquid chamber 43 is depressurized, the liquid flows into the discharge side liquid chamber 43 from the second common liquid chamber 27 of each liquid injection head 20 through the liquid discharge passage 40. In each liquid injection head 20, when the liquid flows from the second common liquid chamber 27 into the discharge side liquid chamber 43, the pressure in the second common liquid chamber 27 decreases, so that the injection liquid chamber passes through the second passage 27b. The liquid flows from the 23 to the second common liquid chamber 27. In each liquid injection head 20, when the liquid flows from the injection liquid chamber 23 into the second common liquid chamber 27, the pressure in the injection liquid chamber 23 decreases. In one example of this embodiment, the second pressure is set to a pressure that can maintain the meniscus at the gas-liquid interface of the nozzle 21. Therefore, when the pressure in the discharge side liquid chamber 43 is higher than the second pressure, the meniscus is maintained at the gas-liquid interface of the nozzle 21 when the pressure in the injection liquid chamber 23 of each liquid injection head 20 decreases. The liquid flows from the first common liquid chamber 22 into the injection liquid chamber 23 as it is. That is, when the pressure in the discharge side liquid chamber 43 is higher than the second pressure, when the pressure in the injection liquid chamber 23 of each liquid injection head 20 drops, the air is not drawn from the nozzle 21 and is common to the first. The liquid flows in from the liquid chamber 22. In each liquid injection head 20, when the liquid in the first common liquid chamber 22 flows into the injection liquid chamber 23, the pressure in the first common liquid chamber 22 decreases, so that the pressure on each supply side is adjusted through the liquid supply passage 30. Liquid flows from the supply side liquid chamber 33 of the valve 31 into the first common liquid chamber 22.

Then, the pressure in the supply side liquid chamber 33 drops to the first pressure due to the liquid flowing from the supply side liquid chamber 33 of each supply side pressure adjusting valve 31 into the first common liquid chamber 22 of each liquid injection head 20. Then, the supply side valve body 35 is opened, and the supply side liquid chamber 33 and the supply side communication chamber 34 are communicated with each other. In an example of this embodiment, the supply side communication chamber 34 of each supply side pressure adjusting valve 31 is held in a pressurized state. Therefore, when the supply side valve body 35 is opened in each supply side pressure adjusting valve 31 and the supply side liquid chamber 33 and the supply side communication chamber 34 are communicated with each other, the supply side liquid is connected from the supply side communication chamber 34. The liquid flows into the chamber 33. As a result, the pressure in the supply side liquid chamber 33 of each supply side pressure adjusting valve 31 rises and is adjusted to the first pressure.

In an example of this embodiment, the first pressure is set to the pressure of the supply side liquid chamber 33 capable of maintaining the meniscus at the gas-liquid interface of the nozzle 21 of each liquid injection head 20. Therefore, in the liquid injection device 11a, the pressure in the supply side liquid chamber 33 of each supply side pressure adjusting valve 31 is adjusted to the first pressure, so that the gas-liquid interface of the nozzle 21 of each liquid injection head 20 is reached. Meniscus can be maintained.

On the other hand, in an example of the present embodiment, the second pressure is the pressure in the discharge side liquid chamber 43 capable of maintaining the meniscus at the gas-liquid interface of the nozzle 21 of each liquid injection head 20, and the first pressure. Set to a lower pressure. Therefore, when the liquid in the discharge side liquid chamber 43 is discharged to the return flow path 50 side in the circulation process, in principle, the pressure in the discharge side liquid chamber 43 drops to the second pressure, and the discharge side valve body 46 The pressure in the supply side liquid chamber 33 of each supply side pressure adjusting valve 31 drops to the first pressure and the supply side valve body 35 opens before the valve opens. According to this, in the liquid injection device 11a, before the pressure in the discharge side liquid chamber 43 becomes the second pressure, the supply side communication chamber 34 to the supply side liquid chamber 33 and the liquid of each supply side pressure adjusting valve 31 The liquid can be supplied to the injection liquid chamber 23 via the supply passage 30 and the first common liquid chamber 22. Therefore, in the liquid injection device 11a, the pressure in the injection liquid chamber 23 of each liquid injection head 20 can be adjusted to a pressure that can maintain the meniscus at the gas-liquid interface of the nozzle 21.

However, depending on the amount of liquid discharged when the liquid is discharged from the discharge side liquid chamber 43 to the return flow path 50 side by driving the flow pump 52, the pressure in the discharge side liquid chamber 43 temporarily becomes the second pressure. It can also be assumed that As an example, the amount of liquid discharged when the liquid is discharged from the discharge side liquid chamber 43 to the return flow path 50 side is the amount of the liquid discharged from the supply side communication chamber 34 of each supply side pressure adjusting valve 31 to the supply side liquid chamber 33. If it exceeds the supply amount, it can be assumed that the pressure in the discharge side liquid chamber 43 reaches the second pressure.

In this case, the discharge side valve body 46 is opened, and the discharge side liquid chamber 43 and the first discharge side communication chamber 44 are communicated with each other. Therefore, the fluid introduced into the second discharge side communication chamber 45 from the fluid introduction path 70 flows into the discharge side liquid chamber 43 through the first discharge side communication chamber 44. As a result, the pressure in the discharge side liquid chamber 43 rises and is adjusted to the second pressure. Therefore, in the liquid injection device 11a, the meniscus can be maintained at the gas-liquid interface of the nozzle 21 by adjusting the pressure in the discharge side liquid chamber 43 to the second pressure.

When the control unit 200 allows the fluid to flow from the fluid introduction path 70 into the discharge side liquid chamber 43 via the second discharge side communication chamber 45 and the first discharge side communication chamber 44, the control unit 200 sets the first switching valve 71 to the fluid introduction passage. By switching to a state in which the 70 and the atmospheric communication passage 72 are communicated with each other, the air can flow into the discharge side liquid chamber 43. Further, when the control unit 200 causes the fluid to flow into the discharge side liquid chamber 43 from the fluid introduction path 70 via the second discharge side communication chamber 45 and the first discharge side communication chamber 44, the control unit 200 makes the first switching valve 71 fluid. By switching to a state in which the introduction path 70 and the bypass flow path 73 communicate with each other, the liquid can flow into the discharge side liquid chamber 43 from the temporary storage unit 80.

As described above, in the circulation operation, the liquid in the liquid injection device 11a circulates while maintaining the meniscus at the gas-liquid interface of the nozzle 21.
Further, the liquid injection device 11a may be configured to perform wiping to wipe the nozzle surface 21a with the wiper 103a as a maintenance operation. Wiping can be performed to remove foreign matter such as liquid and dust adhering to the nozzle surface 21a. The control unit 200 can execute wiping by moving the moving body 103b along the nozzle surface 21a in a state where the tip of the wiper 103a is in contact with the nozzle surface 21a. Wiping can also be performed by moving each liquid injection head 20 in contact with the wiper 103a.

Further, the liquid injection device 11a may be configured to perform flushing to discharge the liquid in the nozzle 21 by injecting the liquid from the nozzle 21 of each liquid injection head 20 toward the cap 101 as a maintenance operation. Good. Flushing can be performed to prevent or clear clogging of the nozzle 21 between printings, and can also be performed to prepare the liquid meniscus formed in the nozzle 21 after wiping, for example. it can.

Further, the liquid injection device 11a may be configured to perform a cleaning operation for discharging the liquid from the injection liquid chamber 23 through the nozzle 21 as a maintenance operation. Since the cleaning operation has a larger amount of liquid discharged from the nozzle 21 than flushing, it can be said that the cleaning operation has a greater effect of clearing the clogging of the nozzle 21 than flushing.

The liquid injection device 11a may be configured to perform suction cleaning as a cleaning operation. The control unit 200 can perform suction cleaning by driving the decompression pump 102c in a capped state to reduce the pressure in the closed space and discharge the liquid from the nozzle 21.

Further, the liquid injection device 11a may be configured to perform pressure cleaning as a cleaning operation. Hereinafter, the pressure cleaning process for performing the pressure cleaning will be described.

As shown in FIG. 7, the control unit 200 releases the capping of each liquid injection head 20 in step S21. When the capping is released, the cap 101 is arranged at a position facing the opening of the nozzle surface 21a.

Next, in step S22, the control unit 200 opens the first on-off valve 51 to communicate the flow pump 52 and the discharge side liquid chamber 43. Subsequently, in step S23, the control unit 200 drives the flow pump 52 to start pressurizing the discharge side liquid chamber 43. When the pressure in the discharge side liquid chamber 43 rises, the discharge side valve body 46 closes to shut off the discharge side liquid chamber 43 and the first discharge side communication chamber 44. Therefore, when the pressure in the discharge side liquid chamber 43 rises, the liquid stored in the discharge side liquid chamber 43 is pressurized and supplied to the second common liquid chamber 27 of each liquid injection head 20 through the liquid discharge passage 40. Then, the liquid in the second common liquid chamber 27 flows into the jet liquid chamber 23, flows out from the nozzle 21, and is received by the cap 101. As a result, foreign substances that cause injection failure, such as air bubbles in the second common liquid chamber 27 and the injection liquid chamber 23 and the liquid thickened by evaporation of the solvent component, are discharged through the nozzle 21 together with the liquid.

When a sufficient amount of liquid for discharging the foreign matter is discharged from the nozzle 21, the control unit 200 stops driving the flow pump 52 and stops pressurizing the discharge side liquid chamber 43 in step S24. Further, in step S25, the control unit 200 closes the first on-off valve 51 to shut off the flow pump 52 and the discharge side liquid chamber 43.

Next, the control unit 200 starts driving the pressure reducing pump 102c in step S26. As a result, the liquid accumulated in the cap 101 is discharged to the waste liquid tank 102a through the waste liquid flow path 102b. When the discharge of the liquid in the cap 101 is completed, the control unit 200 stops the drive of the pressure reducing pump 102c in step S27.

After that, in step S28, the control unit 200 moves the moving body 103b and executes wiping. As a result, droplets and the like adhering to the nozzle surface 21a as the liquid is discharged from the nozzle 21 are removed.

Then, in step S29, the control unit 200 executes flushing to prepare the meniscus of the nozzle 21, and in step S30, executes capping to complete the pressure cleaning process. If printing is to be performed immediately after the pressure cleaning is performed, the capping in step S30 may not be performed.

Next, the operation of the liquid injection device 11a of the present embodiment will be described.
When performing a circulation operation for circulating the liquid in the liquid injection device 11a, the discharge side pressure adjusting valve 41 flexes the discharge side flexible portion 42 when the pressure in the discharge side liquid chamber 43 becomes the second pressure. As a result, the discharge side valve body 46 opens to allow the fluid to flow from the fluid introduction path 70 into the discharge side liquid chamber 43. Therefore, in the discharge side pressure adjusting valve 41, even when the liquid is discharged to the return flow path 50 side in the circulation operation, the pressure in the discharge side liquid chamber 43 can form a meniscus at the gas-liquid interface of the nozzle 21. It is adjusted to a second pressure.

Further, in the case of performing the circulation operation, the supply side pressure adjusting valve 31 bends the supply side flexible portion 32 when the pressure in the supply side liquid chamber 33 becomes the first pressure, so that the supply side valve body 35 Opens the valve to allow liquid to flow from the supply side communication chamber 34 into the supply side liquid chamber 33. Therefore, in the supply side pressure adjusting valve 31, the pressure in the supply side liquid chamber 33 can form a meniscus at the gas-liquid interface of the nozzle 21 even when the liquid is discharged to the return flow path 50 side in the circulation operation. It is adjusted to the first pressure.

The liquid discharge passage 40 is connected to the discharge side liquid chamber 43 in the second communication hole 43b located below the first communication hole 43a in which the fluid flowing from the fluid introduction passage 70 flows into the discharge side liquid chamber 43 in the vertical direction Z. Connecting. Therefore, the liquid injection device 11a can prevent the fluid flowing in from the fluid introduction path 70 from flowing to the second communication hole 43b side.

The return flow path 50 is connected to the discharge side liquid chamber 43 in the third communication hole 43c located above the first communication hole 43a in which the fluid flowing from the fluid introduction path 70 flows into the discharge side liquid chamber 43 in the vertical direction Z. Connecting. Therefore, the liquid injection device 11a can guide the fluid flowing in from the fluid introduction path 70 to the third communication hole 43c side.

The fluid introduction path 70 can communicate with the bypass flow path 73 connected to the upstream side liquid supply path 30a on the upstream side of the supply side liquid chamber 33 in the liquid supply path 30. Therefore, in the liquid injection device 11a, the same liquid as the liquid supplied from the liquid supply path 30 to each liquid injection head 20 can flow into the discharge side liquid chamber 43 from the fluid introduction path 70.

The fluid introduction path 70 can be connected to the atmospheric communication passage 72. Therefore, in the liquid injection device 11a, the atmosphere can flow into the discharge side liquid chamber 43 from the fluid introduction path 70.
The difference between the pressure in the discharge side liquid chamber 43 and the pressure applied to the nozzle 21 during the circulation operation increases as the flow path resistance from the discharge side liquid chamber 43 to the nozzle 21 increases. In an example of this embodiment, the flow path resistance of the second flow path R2 between the nozzle 21 and the discharge side liquid chamber 43 is the flow path of the first flow path R1 between the supply side liquid chamber 33 and the nozzle 21. Less than resistance. Therefore, the difference between the pressure in the discharge side liquid chamber 43 and the pressure applied to the nozzle 21 can be reduced.

The flow path resistance of the second passage 27b is larger than the flow path resistance of the first passage 22b. Therefore, when the liquid is discharged from the nozzle 21, the liquid is easily flowed from the first common liquid chamber 22 into the injection liquid chamber 23, and the liquid flows from the second common liquid chamber 27 into the injection liquid chamber 23. Can be suppressed.

When the liquid is discharged from the discharge side liquid chamber 43 to the return flow path 50 side, the discharge side pressure adjusting valve 41 bends the discharge side flexible portion 42, so that the volume of the discharge side liquid chamber 43 becomes smaller. Therefore, the discharge side pressure adjusting valve 41 connects each liquid injection head to the discharge side liquid chamber 43 via the liquid discharge path 40 when the liquid is discharged from the discharge side liquid chamber 43 to the return flow path 50 side. The amount of liquid drawn from the second common liquid chamber 27 of 20 can be reduced. That is, the discharge side pressure adjusting valve 41 reduces the pressure fluctuation generated inside each liquid injection head 20 when the liquid is discharged from the discharge side liquid chamber 43 to the return flow path 50 side. Further, the volume of the discharge side liquid chamber 43 in which the discharge side flexible portion 42 can be changed is larger than the volume of the supply side liquid chamber 33 in which the supply side flexible portion 32 can be changed. Therefore, the discharge side pressure adjusting valve 41 can suitably reduce the pressure fluctuation even when the amount of liquid discharged from the discharge side liquid chamber 43 to the return flow path 50 side is large.

Each liquid injection head 20, each supply side pressure adjusting valve 31, and discharging side pressure adjusting valve 41 are held in the head holder 90 in a state where they do not move relative to each other. Therefore, the distance between the nozzle surface 21a and each supply-side pressure adjusting valve 31 in the vertical direction Z does not change even when the head holder 90 is displaced along the vertical direction Z. Therefore, in one example of the present embodiment, it is possible to suppress the change in the pressure applied to the nozzle 21 by changing the distance between the nozzle surface 21a and each supply side pressure adjusting valve 31 in the vertical direction Z.

Further, the distance between the nozzle surface 21a and the discharge side pressure adjusting valve 41 in the vertical direction Z does not change even when the head holder 90 is displaced along the vertical direction Z. Therefore, in one example of the present embodiment, it is possible to suppress the change in the pressure applied to the nozzle 21 by changing the distance between the nozzle surface 21a and the discharge side pressure adjusting valve 41 in the vertical direction Z.

The effect of this embodiment will be described.
(1) The liquid injection device 11a has a discharge side pressure adjusting valve 41 in a liquid discharge path 40 for discharging liquid from each liquid injection head 20. Therefore, the liquid injection device 11a can reduce the pressure fluctuation in the nozzle 21 when the liquid is discharged from the liquid outlet 27a by driving the flow pump 52 in the circulation operation of circulating the liquid. Therefore, the liquid injection device 11a can prevent the pressure control when performing the circulation operation from becoming complicated.

(2) The liquid injection device 11a can adjust the pressure of the supply side liquid chamber 33 by the supply side pressure adjusting valve 31. Therefore, the liquid injection device 11a can easily control the pressure of the supply side liquid chamber 33 as compared with the case where the pressure of the supply side liquid chamber 33 is adjusted by using, for example, a pump and a sensor.

(3) Since the liquid injection device 11a can reduce the pressure fluctuation in the supply side liquid chamber 33 by bending the supply side flexible portion 32, the pressure control of the supply side liquid chamber 33 can be easily performed.
(4) Since the liquid injection device 11a can reduce the pressure fluctuation in the discharge side liquid chamber 43 by bending the discharge side flexible portion 42, the pressure control of the discharge side liquid chamber 43 can be easily performed.

(5) The liquid injection device 11a can suppress the fluid flowing from the fluid introduction path 70 into the discharge side liquid chamber 43 from flowing into the liquid discharge path 40 side.
(6) The liquid injection device 11a can efficiently discharge the fluid that has flowed into the discharge side liquid chamber 43 from the fluid introduction path 70 from the discharge side liquid chamber 43 via the return flow path 50.

(7) When the discharge side liquid chamber 43 becomes the second pressure, the liquid injection device 11a introduces the same liquid as the liquid supplied to each liquid injection head 20 into the discharge side liquid chamber 43, thereby causing the discharge side. The pressure in the liquid chamber 43 can be maintained.

(8) In the liquid injection device 11a, the pressure inside the discharge side liquid chamber 43 is lower than the second pressure in a state where the first switching valve 71 is switched to a state in which the fluid introduction path 70 and the atmospheric communication passage 72 are communicated with each other. By driving the flow pump 52, the liquid in the discharge side pressure adjusting valve 41 and the return flow path 50 can be discharged through the return flow path 50.

(9) The liquid injection device 11a is set so that the inside of the discharge side liquid chamber 43 becomes lower than the second pressure in a state where the first switching valve 71 is switched to a state in which the fluid introduction path 70 and the atmospheric communication passage 72 are communicated with each other. By driving the flow pump 52, the atmosphere can be introduced into the discharge side liquid chamber 43. Therefore, as an example of a liquid, when an ink that solidifies when the amount of oxygen in the liquid decreases is used, the solidification of the liquid can be suppressed.

(10) Since the liquid injection device 11a includes the degassing unit 60, even when the air is introduced into the discharge side liquid chamber 43, the liquid is supplied to each liquid injection head 20 while containing the atmosphere. Can be suppressed.

(11) In the liquid injection device 11a, the flow path resistance of the second flow path R2 between the nozzle 21 and the discharge side liquid chamber 43 is the flow path resistance of the first flow path R1 between the supply side liquid chamber 33 and the nozzle 21. It is smaller than the flow path resistance. Therefore, the difference between the pressure in the discharge side liquid chamber 43 and the pressure applied to the nozzle 21 can be reduced. Therefore, by adjusting the pressure in the discharge side liquid chamber 43, the pressure applied to the nozzle 21 can be adjusted accurately.

(12) The liquid injection device 11a facilitates the inflow of the liquid from the first common liquid chamber 22 into the injection liquid chamber 23 when the liquid is discharged from the nozzle 21, and the liquid injection chamber 23 from the second common liquid chamber 27. It is possible to suppress the inflow of liquid into the water. Therefore, when the liquid is discharged from the nozzle 21, the liquid can flow into the injection liquid chamber 23 from the liquid supply path 30 side.

(13) The discharge side pressure adjusting valve 41 reduces the pressure fluctuation generated inside each liquid injection head 20 when the liquid is discharged from the discharge side liquid chamber 43 to the return flow path 50 side in the circulation operation. Therefore, the liquid injection device 11a can reduce the fluctuation of the pressure applied to the nozzle 21 during the circulation operation.

(14) The volume of the discharge side liquid chamber 43 in which the discharge side flexible portion 42 can be changed is larger than the volume of the supply side liquid chamber 33 in which the supply side flexible portion 32 can be changed. Therefore, even when the amount of liquid discharged from the discharge side liquid chamber 43 to the return flow path 50 side is large, the discharge side pressure adjusting valve 41 has a discharge side liquid chamber due to the displacement of the discharge side flexible portion 42. By reducing the volume of 43, the fluctuation of the pressure in the discharge side liquid chamber 43 can be suitably reduced. Therefore, the liquid injection device 11a can suitably reduce the fluctuation of the pressure applied to the nozzle 21.

(15) Each liquid injection head 20 and each supply side pressure adjusting valve 31 are held in the head holder 90 in a state where they do not move relative to each other. Therefore, in the liquid injection device 11a, when the head holder 90 is displaced, the pressure applied to the nozzle 21 changes by changing the distance between the nozzle surface 21a and each supply side pressure adjusting valve 31 in the vertical direction Z. Can be suppressed.

(16) Each liquid injection head 20 and the discharge side pressure adjusting valve 41 are held in the head holder 90 in a state where they do not move relative to each other. Therefore, in the liquid injection device 11a, when the head holder 90 is displaced, the pressure applied to the nozzle 21 changes due to the change in the distance between the nozzle surface 21a and the discharge side pressure adjusting valve 41 in the vertical direction Z. Can be suppressed.

(Second Embodiment)
Next, a second embodiment of the liquid injection device and the control method of the liquid injection device will be described with reference to the drawings. The second embodiment does not include the discharge side pressure adjusting valve 41, the return flow path 50, and the fluid introduction path 70, but the nozzle depends on the position where the liquid tank, which is an example of the liquid storage unit 15, is arranged. It is different from the case of the first embodiment in that the pressure applied to 21 is adjusted. Since it is almost the same as the first embodiment in other respects, duplicate description will be omitted by assigning the same reference numerals to the same configurations.

As shown in FIG. 8, the liquid discharge path 40 is connected between the degassing section 60 and the supply side pressure adjusting valve 31 in the liquid supply path 30. That is, the liquid discharge path 40 is connected to the upstream side liquid supply path 30a, which is on the upstream side of the supply side liquid chamber 33 in the liquid supply path 30.

The liquid injection device 11a has an upstream liquid supply path at the connection portion between the liquid discharge path 40 and the liquid supply path 30 through a liquid flow path from the degassing section 60 to the first common liquid chamber 22 of each liquid injection head 20. It is preferable to provide a third switching valve 110 that can be switched between the 30a and the liquid discharge path 40. As an example, the third switching valve 110 connects the liquid discharge path 40 on the upstream side of the connection portion between the liquid discharge path 40 and the liquid discharge path 40 in the upstream liquid supply path 30a and the liquid discharge path 40 in the upstream liquid supply path 30a. It can be a three-way valve provided with three valve bodies capable of individually closing the three flow paths on the downstream side of the portion.

The liquid discharge path 40 branches between each liquid injection head 20 and the third switching valve 110, and is connected to a liquid storage section 15 which is an example of a liquid storage section. That is, the liquid discharge path 40 has a branch portion 40a that branches. The liquid injection device 11a has a third on-off valve 120 as an example of a storage unit pressure adjusting mechanism provided between each liquid injection head 20 and the liquid storage unit 15 in the liquid discharge path 40. When the third on-off valve 120 is closed, the liquid discharge path 40 is closed on the liquid storage portion 15 side of the branch portion 40a. In other words, when the third on-off valve 120 is opened, the liquid accommodating portion 15 and each liquid injection head 20 are communicated with each other via the liquid discharge path 40. That is, when the third on-off valve 120 is opened, the pressure in the liquid accommodating portion 15 is applied to the nozzle 21 via the liquid discharge path 40. In an example of the present embodiment, the pressure in the liquid storage unit 15 is determined by the pressure applied to the liquid surface of the liquid stored in the liquid storage unit 15. The pressure in the liquid storage unit 15 may be determined by the pressure applied to an arbitrary position in the liquid storage unit 15.

The liquid injection device 11a includes a pressure damper 121 that reduces fluctuations in pressure in the liquid discharge path 40 between the branch portion 40a and the third on-off valve 120 of the liquid discharge path 40. That is, the liquid injection device 11a includes a pressure damper 121 between each liquid injection head 20 and the third on-off valve 120 in the liquid discharge path 40. As an example, the pressure damper 121 includes a pressure adjusting chamber 123 whose volume is changed by bending the pressure adjusting flexible portion 122 constituting the wall portion. In the pressure damper 121, when the amount of liquid in the liquid discharge path 40 increases, the pressure adjusting flexible portion 122 bends so as to increase the volume of the pressure adjusting chamber 123, while the liquid in the liquid discharge path 40 When the amount decreases, the pressure adjusting flexible portion 122 bends so as to reduce the volume of the pressure adjusting chamber 123. As a result, the liquid injection device 11a can reduce the fluctuation of the pressure in the liquid discharge path 40. The liquid injection device 11a includes a discharge flow pump 124 for flowing a liquid between the third on-off valve 120 and the liquid storage portion 15 in the liquid discharge path 40.

The liquid injection device 11a includes a holding unit 15a that holds the liquid storage unit 15. The liquid storage unit 15 is held by the holding unit 15a so that the position of the liquid surface in the liquid storage unit 15 in the vertical direction Z is within the range from the first position H1 to the second position H2. The first position H1 is the position of the liquid level when the liquid storage unit 15 stores the maximum amount of liquid that can be stored. The second position H2 is the position of the liquid level when the minimum amount of liquid that can be supplied from the liquid storage unit 15 to the liquid supply path 30 is stored.

In an example of the present embodiment, the first position H1 and the second position H2 are used as potential energy of the liquid in the liquid storage unit 15 when the inside of the liquid storage unit 15 is open to the atmosphere as shown in FIG. Is the position of the liquid level in the liquid storage portion 15 when the pressure of the above is lower than the first pressure and the pressure is such that the gas-liquid interface formed in the nozzle 21 is maintained. That is, in an example of the present embodiment, the pressure in the liquid storage portion 15 is lower than the first pressure because the liquid storage portion 15 is held by the holding portion 15a, and the gas-liquid interface formed in the nozzle 21. Is adjusted to a second pressure that is maintained. That is, the holding unit 15a holds the liquid storage unit 15 at a position where the pressure in the liquid storage unit 15 acting on the nozzle 21 via the liquid discharge path 40 becomes the second pressure.

At this time, the difference between the pressure applied to the nozzle 21 and the pressure in the liquid storage portion 15 changes depending on the distance between the position of the nozzle surface 21a in the vertical direction Z and the position of the liquid surface in the liquid storage portion 15. Therefore, the pressure applied to the nozzle 21 when the position of the liquid surface in the liquid accommodating portion 15 is the first position H1 changes depending on the distance D3 between the position of the nozzle surface 21a in the vertical direction Z and the first position H1. To do. Further, the pressure applied to the nozzle 21 when the position of the liquid surface in the liquid accommodating portion 15 is the second position H2 changes depending on the distance D4 between the position of the nozzle surface 21a in the vertical direction Z and the second position H2. ..

In the present embodiment, the control unit 200 controls the third on-off valve 120 and the discharge flow pump 124.
Next, a method of controlling the liquid injection device 11a by the control unit 200 will be described.

The control unit 200 causes the pressure in the liquid storage unit 15 to act on the nozzle 21 by opening the third on-off valve 120. Here, the pressure in the liquid accommodating portion 15 is adjusted to a second pressure that is lower than the first pressure and maintains the gas-liquid interface formed in the nozzle 21. Therefore, the control unit 200 causes the nozzle 21 to act on the pressure in the liquid storage unit 15 adjusted to a second pressure that is lower than the first pressure and maintains the gas-liquid interface formed in the nozzle 21. Then, the liquid in each liquid injection head 20 is discharged to the liquid discharge path 40 side.

Next, the circulation operation in this embodiment will be described.
The control unit 200 drives the pressure pump 81 and the discharge pump 88 to supply the liquid in the liquid storage unit 15 to the liquid supply path 30 side. That is, the pressurizing pump 81 and the discharge pump 88 allow the liquid stored in the liquid accommodating portion 15 to flow toward each supply-side pressure adjusting valve 31 via the liquid supply path 30. In the present embodiment, the pressurizing pump 81 and the discharge pump 88 are examples of the liquid flow mechanism.

Subsequently, when the liquid in each liquid injection head 20 is discharged to the liquid discharge path 40 side, the control unit 200 opens the third on-off valve 120 and the liquid storage unit 15 via the liquid discharge path 40. And each liquid injection head 20 are communicated with each other. According to this, the pressure in the liquid accommodating portion 15 acts on the nozzle 21 of each liquid injection head 20. Therefore, the liquid in each liquid injection head 20 can be discharged to the liquid storage portion 15 having a lower pressure. That is, the control unit 200 controls the third on-off valve 120 to apply the pressure in the liquid storage unit 15 to the nozzle 21 via the liquid discharge path 40, thereby causing the liquid in each liquid injection head 20 to be applied. The liquid is discharged to the liquid discharge path 40 side.

At this time, the pressure in the liquid storage portion 15 is adjusted to a second pressure at which the gas-liquid interface formed in the nozzle 21 is maintained. Therefore, in the liquid injection device 11a, the meniscus can be maintained at the gas-liquid interface of the nozzle 21 when the liquid in the liquid injection device 11a is circulated.

After that, the control unit 200 closes the third on-off valve 120 to shut off the liquid storage unit 15 and each liquid injection head 20. As described above, the liquid injection device 11a can circulate the liquid in the liquid injection device 11a.

Next, the operation of the liquid injection device 11a of the present embodiment will be described.
The holding portion 15a adjusts the pressure inside the liquid containing portion 15 to a pressure capable of maintaining the meniscus at the gas-liquid interface of the nozzle 21 by holding the liquid containing portion 15 at a predetermined position. Then, when the control unit 200 performs a circulation operation for circulating the liquid in the liquid injection device 11a, the pressure in the liquid storage unit 15 is applied to the nozzle 21 by opening the third on-off valve 120. That is, the pressure applied to the nozzle 21 in the circulation operation is adjusted to a pressure that can maintain the meniscus at the gas-liquid interface of the nozzle 21.

The effect of this embodiment will be described.
(17) Since the liquid injection device 11a has a supply-side pressure adjusting valve 31 on the liquid supply path 30 side for supplying the liquid to each liquid injection head 20, the pressure in the liquid storage portion 15 connected to the liquid discharge path 40. The pressure in the nozzle 21 can be adjusted by adjusting. Therefore, the liquid injection device 11a can prevent the pressure control when performing the circulation operation of circulating the liquid from becoming complicated.

(18) The liquid injection device 11a can easily perform a circulation operation of discharging the liquid in each liquid injection head 20 to the liquid discharge path 40 side by opening and closing the third on-off valve 120.
(19) Since the liquid injection device 11a includes a pressure damper 121 between each liquid injection head 20 and the third on-off valve 120 in the liquid discharge path 40, the pressure at which the third on-off valve 120 is opened and closed. It is possible to reduce the influence of fluctuations on each liquid injection head 20.

(20) The liquid injection device 11a adjusts the pressure on the liquid supply passage 30 side to the first pressure by the pressurized liquid supply passage 30 and the supply side pressure adjusting valve 31, and discharges the liquid depending on the position of the liquid storage portion 15. The pressure on the road 40 side can be adjusted to the second pressure.

(21) According to the control method by the control unit 200, the pressure in the liquid storage unit 15 adjusted to a second pressure that is lower than the first pressure and does not break the gas-liquid interface formed in the nozzle 21. The liquid in each liquid injection head 20 can be discharged to the liquid discharge path 40 side by acting on the nozzle 21 via the liquid discharge path 40. Therefore, it is possible to prevent the pressure control from becoming complicated when performing the circulation operation of circulating the liquid.

(22) According to the control method by the control unit 200, by opening the third on-off valve 120, the pressure is lower than the first pressure and the gas-liquid interface formed in the nozzle 21 is not broken. The pressure in the adjusted liquid storage portion 15 is applied to the nozzle 21 via the liquid discharge path 40. Therefore, it is possible to prevent the pressure control from becoming complicated when performing the circulation operation of circulating the liquid.

(Third Embodiment)
Next, a third embodiment of the liquid injection device will be described with reference to the drawings. The third embodiment is different from the case of the first embodiment in that the discharge side pressure adjusting valve 41 is not held by the head holder 90 and the bypass flow path 73 is not provided. Since it is almost the same as the first embodiment in other respects, duplicate description will be omitted by assigning the same reference numerals to the same configurations.

As shown in FIGS. 9 and 10, the discharge side pressure adjusting valve 41 is provided at a position where the center position of the pressure of the discharge side liquid chamber 43 is lower than the nozzle surface 21a by a distance D5 in the vertical direction Z. There is. Further, the discharge side pressure adjusting valve 41 is provided at a position where the center position of the pressure of the discharge side liquid chamber 43 is lower than the center position of the pressure of the supply side liquid chamber 33 in the vertical direction Z by a distance D6. .. The discharge side pressure adjusting valve 41 is provided outside the head holder 90. That is, the discharge side pressure adjusting valve 41 is configured so that the position of the discharge side liquid chamber 43 in the vertical direction Z does not change even when the head holder 90 is displaced along the vertical direction Z.

The fluid introduction path 70 is connected to the atmospheric communication passage 72. Further, the liquid injection device 11a includes a fourth on-off valve 130 that shuts off the fluid introduction path 70 and the atmospheric communication passage 72 when the valve is closed. The fourth on-off valve 130 is provided above the nozzle surface 21a in the vertical direction Z. The open end 72a of the atmospheric passage 72 that is open to the atmosphere is provided above the nozzle surface 21a in the vertical direction Z.

Next, the operation of the liquid injection device 11a of the present embodiment will be described.
The position of the discharge side liquid chamber 43 in the vertical direction Z does not change even when the head holder 90 is displaced along the vertical direction Z. Therefore, the pressure in the discharge side liquid chamber 43 does not change even when the head holder 90 is displaced along the vertical direction Z.

Further, the open end 72a of the fourth on-off valve 130 and the atmospheric communication passage 72 is provided above the nozzle surface 21a in the vertical direction Z. Therefore, when the fourth on-off valve 130 is opened, the gas-liquid interface in the flow path formed by the fluid introduction path 70 and the atmospheric communication passage 72 is formed below the fourth on-off valve 130. To.

The effect of this embodiment will be described.
(23) Since the pressure in the discharge side liquid chamber 43 does not change even when the head holder 90 is displaced along the vertical direction Z, the pressure in the discharge side liquid chamber 43 can be controlled accurately.

(24) When the fourth on-off valve 130 is opened, the gas-liquid interface in the flow path formed by the fluid introduction path 70 and the atmospheric communication passage 72 is formed below the fourth on-off valve 130. Will be done. Therefore, it is possible to prevent the liquid from leaking from the open end 72a of the atmospheric communication passage 72.

(Fourth Embodiment)
Next, a fourth embodiment of the liquid injection device will be described with reference to the drawings. In this fourth embodiment, as the supply-side pressure adjusting mechanism, instead of the supply-side pressure adjusting valve 31, the supply-side liquid storage unit 140 capable of storing liquid and the pressure in the supply-side liquid storage unit 140 are adjusted. It is different from the case of the first embodiment in that the supply side storage unit pressure adjusting mechanism 141 is provided. Since it is almost the same as the first embodiment in other respects, duplicate description will be omitted by assigning the same reference numerals to the same configurations.

As shown in FIG. 11, the supply-side liquid storage unit 140 is provided between the temporary storage unit 80 and each liquid injection head 20 in the liquid supply path 30. Then, the supply-side liquid storage unit 140 communicates with the temporary storage unit 80 via the liquid supply path 30, and also communicates with each liquid injection head 20.

The supply-side storage unit pressure adjusting mechanism 141 can adjust the pressure in the supply-side liquid storage unit 140 by adjusting the amount of gas in the supply-side liquid storage unit 140. In an example of this embodiment, the pressure in the supply-side liquid storage unit 140 is determined by the pressure of the gas at a predetermined position in the supply-side liquid storage unit 140. The pressure in the supply-side liquid storage unit 140 may be determined by the pressure applied to an arbitrary position in the supply-side liquid storage unit 140. As an example, the pressure in the supply-side liquid storage unit 140 may be determined by the pressure applied to the liquid level of the liquid contained in the supply-side liquid storage unit 140, or may be applied to the bottom surface of the supply-side liquid storage unit 140. It may be determined by pressure.

In one example of the present embodiment, the supply-side storage unit pressure adjusting mechanism 141 has an open air passage 141a in which one end is connected to the supply-side liquid storage unit 140 and the other end is open to the atmosphere, and the inside of the supply-side liquid storage unit 140. It is provided with a pressure gauge 141b for measuring the pressure of the above, and a gas discharge pump 141c for driving the gas in the supply side liquid storage unit 140 so as to be discharged. Further, the supply-side storage unit pressure adjusting mechanism 141 includes an atmosphere opening valve 141d that closes the atmosphere opening path 141a when the valve is closed. The pressure gauge 141b is preferably a relative pressure gauge that measures the pressure difference from the atmospheric pressure.

Then, when the pressure in the supply-side liquid storage unit 140 measured by the pressure gauge 141b is higher than the first pressure, the control unit 200 opens the atmosphere release valve 141d and drives the gas discharge pump 141c. The gas in the supply-side liquid storage unit 140 is discharged to reduce the pressure in the supply-side liquid storage unit 140.

Next, the operation of the liquid injection device 11a of the present embodiment will be described.
The supply-side liquid storage unit 140 stores the liquid supplied from the temporary storage unit 80 by communicating with the temporary storage unit 80 via the liquid supply path 30 and also with each liquid injection head 20. At the same time, the stored liquid is supplied to each liquid injection head 20. Further, since the supply-side liquid storage unit 140 and each liquid injection head 20 communicate with each other, the pressure applied to the nozzle 21 of each liquid injection head 20 varies depending on the pressure in the supply-side liquid storage unit 140. ..

Then, when the pressure in the supply-side liquid storage unit 140 is higher than the first pressure, the control unit 200 reduces the pressure in the supply-side liquid storage unit 140 to the liquid level of the liquid in the supply-side liquid storage unit 140. By controlling the pressure of the acting gas to be low, the pressure in the supply-side liquid storage unit 140 is adjusted to be equal to or lower than the first pressure.

The effect of this embodiment will be described.
(25) Since the liquid injection device 11a can adjust the pressure in the supply-side liquid storage unit 140 to be equal to or lower than the first pressure under the control of the control unit 200, the pressure applied to the nozzle 21 can be adjusted accurately.

(Fifth Embodiment)
Next, a fifth embodiment of the liquid injection device and the control method of the liquid injection device will be described with reference to the drawings. The fifth embodiment is different from the second embodiment in that the liquid storage unit is provided with a sub-liquid storage unit 150 provided in the liquid discharge path 40 and capable of storing the liquid. Since it is substantially the same as the second embodiment in other respects, duplicate description will be omitted by assigning the same reference numerals to the same configurations.

As shown in FIG. 12, the sub-liquid accommodating portion 150 is provided between the third on-off valve 120 and the liquid accommodating portion 15 in the liquid discharge path 40. The sub-liquid accommodating unit 150 communicates with each liquid injection head 20 via the liquid discharge path 40, and also communicates with the liquid accommodating unit 15 via the liquid discharge path 40. Further, the liquid injection device 11a includes a fifth on-off valve 151 that closes the liquid discharge path 40 by closing the valve between the sub-liquid storage section 150 and the liquid storage section 15 in the liquid discharge path 40. .. Further, the liquid injection device 11a includes a sub-holding unit 152 that holds the sub-liquid accommodating unit 150 as an example of the storage unit pressure adjusting mechanism.

Even if the sub-liquid storage unit 150 is held by the sub-holding unit 152 so that the position of the liquid level in the sub-liquid storage unit 150 in the vertical direction Z is within the range from the third position H3 to the fourth position H4. Good. The third position H3 is the position of the liquid level when the sub-liquid accommodating portion 150 is accommodating the maximum amount of liquid that can be accommodated. The fourth position H4 is the position of the liquid level when the sub-liquid accommodating portion 150 stores the minimum amount of liquid capable of supplying the liquid to each liquid injection head 20 and the liquid accommodating portion 15.

In an example of the present embodiment, the position of the liquid level in the sub-liquid storage unit 150 within the range from the third position H3 to the fourth position H4 is when the inside of the sub-liquid storage unit 150 is open to the atmosphere. When the pressure of the liquid in the sub-liquid accommodating portion 150 as the position energy is lower than the first pressure and the pressure at which the gas-liquid interface formed in the nozzle 21 is maintained, the pressure in the sub-liquid accommodating portion 150 is maintained. The position of the liquid level. That is, in an example of the present embodiment, the pressure in the sub-liquid accommodating portion 150 is lower than the first pressure and is formed in the nozzle 21 by holding the sub-liquid accommodating portion 150 by the sub-holding portion 152. It is adjusted to a second pressure that maintains the gas-liquid interface. That is, the sub-holding unit 152 holds the sub-liquid accommodating unit 150 at a position where the pressure in the sub-liquid accommodating unit 150 acting on the nozzle 21 via the liquid discharge path 40 becomes the second pressure. In an example of the present embodiment, the pressure in the sub-liquid storage unit 150 is determined by the pressure of the gas at a predetermined position in the sub-liquid storage unit 150. The pressure in the sub-liquid accommodating portion 150 may be determined by the pressure applied to an arbitrary position in the sub-liquid accommodating portion 150. As an example, the pressure in the sub-liquid storage unit 150 may be determined by the pressure applied to the liquid surface of the liquid contained in the sub-liquid storage unit 150, or may be determined by the pressure applied to the bottom surface of the sub-liquid storage unit 150. May be done.

At this time, the difference between the pressure applied to the nozzle 21 and the pressure in the sub-liquid accommodating portion 150 changes depending on the distance between the position of the nozzle surface 21a in the vertical direction Z and the position of the liquid surface in the sub-liquid accommodating portion 150. Therefore, the pressure applied to the nozzle 21 when the position of the liquid surface in the sub-liquid accommodating portion 150 is the third position H3 depends on the distance D7 between the position of the nozzle surface 21a in the vertical direction Z and the third position H3. Change. Further, the pressure applied to the nozzle 21 when the position of the liquid surface in the liquid accommodating portion 15 is the fourth position H4 changes depending on the distance D8 between the position of the nozzle surface 21a in the vertical direction Z and the fourth position H4. ..

Further, the liquid injection device 11a includes, as an example of the storage unit pressure adjusting mechanism, a gas amount adjusting mechanism 153 that adjusts the pressure in the sub-liquid accommodating unit 150 by adjusting the amount of gas in the sub-liquid accommodating unit 150. ..

The gas amount adjusting mechanism 153 includes a sub-atmosphere opening path 153a in which one end is connected to the sub-liquid accommodating portion 150 and the other end is open to the atmosphere, and a sub-pressure gauge 153b for measuring the pressure in the sub-liquid accommodating portion 150. It includes a gas amount adjusting pump 153c that is driven to adjustably drive the amount of gas in the sub-liquid accommodating portion 150. Further, the gas amount adjusting mechanism 153 includes a sub-atmosphere opening valve 153d that closes the sub-atmosphere opening path 153a when the valve is closed. The sub-pressure gauge 153b is preferably a relative pressure gauge that measures the pressure difference from the atmospheric pressure.

Then, when the pressure in the sub-liquid accommodating unit 150 measured by the sub-pressure gauge 153b is not the second pressure, the control unit 200 opens the sub-atmosphere release valve 153d and drives the gas amount adjusting pump 153c. Then, the amount of gas in the sub-liquid storage unit 150 is adjusted, and the pressure in the sub-liquid storage unit 150 is controlled to be the second pressure.

Next, the operation of the liquid injection device 11a of the present embodiment will be described.
The pressure in the sub-liquid accommodating portion 150 is adjusted to a second pressure capable of maintaining the meniscus at the gas-liquid interface of the nozzle 21 by holding the sub-liquid accommodating portion 150 in a predetermined position by the sub-holding portion 152. .. In other words, the sub-holding unit 152 adjusts the pressure in the sub-liquid accommodating unit 150 to a second pressure capable of maintaining the meniscus at the gas-liquid interface of the nozzle 21 by holding the sub-liquid accommodating unit 150 in a predetermined position. To do. Then, when the control unit 200 performs a circulation operation for circulating the liquid in the liquid injection device 11a, the pressure in the auxiliary liquid storage unit 150 is applied to the nozzle 21 by opening the third on-off valve 120. That is, the pressure applied to the nozzle 21 in the circulation operation is adjusted to a pressure that can maintain the meniscus at the gas-liquid interface of the nozzle 21.

Further, when the pressure in the sub-liquid accommodating unit 150 is not the second pressure, the control unit 200 controls the gas amount adjusting mechanism 153 to set the pressure in the sub-liquid accommodating unit 150 to the second pressure. adjust.

Next, a method of controlling the liquid injection device 11a by the control unit 200 will be described.
When the liquid in each liquid injection head 20 is discharged to the liquid discharge path 40 side, the control unit 200 executes a step of measuring the pressure in the sub liquid storage unit 150 by the sub pressure gauge 153b. Subsequently, the control unit 200 opens the sub-atmosphere release valve 153d and drives the gas amount adjusting pump 153c according to the measured pressure to lower the pressure in the sub-liquid storage unit 150 to be lower than the first pressure. And the step of adjusting to the second pressure at which the gas-liquid interface formed in the nozzle 21 is maintained is executed. After that, the control unit 200 executes the step of opening the third on-off valve 120. By such a control method, the control unit 200 causes the pressure in the sub-liquid storage unit 150 to act on the nozzle 21 in the circulation operation. That is, the control unit 200 causes the nozzle 21 to act on the pressure in the sub-liquid accommodating unit 150 which is lower than the first pressure and is adjusted to the second pressure at which the gas-liquid interface formed in the nozzle 21 is maintained. Then, the liquid in each liquid injection head 20 is discharged to the liquid discharge path 40 side.

In the circulation operation, the sub-atmosphere release valve 153d is opened to open the inside of the sub-liquid accommodating portion 150 to the atmosphere, and the inside of the sub-liquid accommodating portion 150 adjusted within the range from the third position H3 to the fourth position H4. When the liquid in each liquid injection head 20 is discharged to the liquid discharge path 40 side by applying the pressure of the above to the nozzle 21, the control unit 200 sets the storage unit pressure adjusting mechanism and each on-off valve as follows. You may control it.

For example, when the position of the liquid level of the liquid in the sub-liquid accommodating unit 150 is higher than the third position H3 in the vertical direction Z, the control unit 200 closes the third on-off valve 120 and closes the fifth on-off valve 151. In the state where the valve is open, the sub-atmosphere opening valve 153d is opened and the gas amount adjusting pump 153c is driven to pressurize the inside of the sub-liquid accommodating portion 150 to accommodate the liquid in the sub-liquid accommodating portion 150. The liquid is discharged to the unit 15 side, the position of the liquid level in the sub-liquid storage unit 150 is adjusted to the fourth position H4, the drive of the gas amount adjusting pump 153c is stopped, and the fifth on-off valve 151 is closed. And.

Further, for example, when the position of the liquid level of the liquid in the sub-liquid accommodating portion 150 is lower than the fourth position H4 in the vertical direction Z, the control unit 200 closes the third on-off valve 120 and the fifth on-off valve. With the valve opened 151, the sub-atmosphere opening valve 153d is opened and the gas amount adjusting pump 153c is driven to reduce the pressure inside the sub-liquid accommodating unit 150, thereby accommodating the sub-liquid from the liquid accommodating unit 15 side. The liquid is made to flow into the unit 150, the position of the liquid level in the sub-liquid storage unit 150 is adjusted to the fourth position H4, the drive of the gas amount adjusting pump 153c is stopped, and the fifth on-off valve 151 is closed. It is in a valve state. Then, when the liquid in each liquid injection head 20 is discharged to the liquid discharge path 40 side to perform a circulation operation, the control unit 200 closes the third on-off valve 120 with the sub-atmosphere release valve 153d open. Make it a state.

The effect of this embodiment will be described.
(26) The liquid injection device 11a can adjust the pressure in the nozzle 21 by adjusting the pressure in the sub-liquid accommodating portion 150 connected to the liquid discharge path 40. Therefore, the liquid injection device 11a can prevent the pressure control when performing the circulation operation of circulating the liquid from becoming complicated.

(27) Since the liquid injection device 11a can adjust the pressure in the sub-liquid storage unit 150 to the second pressure under the control of the control unit 200, the pressure applied to the nozzle 21 can be adjusted accurately.
(28) According to the control method by the control unit 200, the pressure in the sub-liquid storage unit 150 adjusted to a second pressure that is lower than the first pressure and does not break the gas-liquid interface formed in the nozzle 21 is applied. The liquid in each liquid injection head 20 can be discharged to the liquid discharge path 40 side by acting on the nozzle 21 via the liquid discharge path 40. Therefore, it is possible to prevent the pressure control from becoming complicated when performing the circulation operation of circulating the liquid.

(29) According to the control method by the control unit 200, by opening the third on-off valve 120, the pressure is lower than the first pressure and the gas-liquid interface formed in the nozzle 21 is not broken. The pressure in the adjusted sub-liquid accommodating portion 150 is applied to the nozzle 21 via the liquid discharge path 40. Therefore, it is possible to prevent the pressure control from becoming complicated when performing the circulation operation of circulating the liquid.

This embodiment can be modified and implemented as follows. The present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
-In a state where the liquid in the liquid injection device 11a is circulated, the liquid injection unit 12 may inject the liquid onto the paper 14 as a recording medium to perform recording.

The flow path between the supply side liquid chamber 33 of each supply side pressure adjusting valve 31 and the nozzle 21 of each liquid injection head 20 in the second embodiment is the first flow path, and between the nozzle 21 and the liquid storage portion 15. When the flow path is the second flow path, the flow path resistance of the second flow path may be smaller than the flow path resistance of the first flow path, as in the first embodiment.

The flow path between the supply side liquid chamber 33 of each supply side pressure adjusting valve 31 and the nozzle 21 of each liquid injection head 20 in the fifth embodiment is the first flow path, and the flow path from the nozzle 21 to the auxiliary liquid accommodating portion 150. When the flow path between them is the second flow path, the flow path resistance of the second flow path may be smaller than the flow path resistance of the first flow path, as in the first embodiment.

-As shown in FIGS. 2, 9, and 10, the posture of the discharge side pressure adjusting valve 41 can be appropriately changed in the first embodiment, the third embodiment, and the fourth embodiment. As an example, as shown in FIG. 2, the discharge side pressure adjusting valve 41 may be provided in a posture in which the discharge side flexible portion 42 is the bottom surface of the discharge side liquid chamber 43. Further, as shown in FIGS. 9 and 10, the discharge side pressure adjusting valve 41 may be provided in a posture in which the discharge side flexible portion 42 serves as a side wall of the discharge side liquid chamber 43. That is, the discharge side pressure adjusting valve 41 has a vertical direction Z in the discharge side liquid chamber 43 than the first communication hole 43a in which the second communication hole 43b communicating with the liquid discharge passage 40 communicates with the first discharge side communication chamber 44. The third communication hole 43c, which is located below the return flow path 50 and communicates with the return flow path 50, may be provided in a posture located above the first communication hole 43a in the vertical direction Z.

-In the third embodiment, the fluid introduction passage 70 may be connected to the atmospheric communication passage 72 and the bypass passage 73 via the first switching valve 71. In this case, the open end 72a of the first switching valve 71 and the atmospheric communication passage 72 may be provided above the nozzle surface 21a in the vertical direction Z. Further, while the fluid introduction path 70 is connected to the bypass flow path 73, it does not have to be connected to the atmospheric communication passage 72.

In the fifth embodiment, the control unit 200 opens and closes the sub-atmosphere release valve 153d and the gas amount adjusting pump 153c so that the pressure in the sub-liquid accommodating unit 150 measured by the sub-pressure gauge 153b becomes the second pressure. The pressure in the sub-liquid accommodating portion 150 may be applied to the nozzle 21 to discharge the liquid in each liquid injection head 20 to the liquid discharge path 40 side while controlling the drive of the liquid. In this case, the position of the liquid surface in the sub-liquid accommodating portion 150 in the vertical direction Z does not have to be adjusted within the range from the third position H3 to the fourth position H4.

-In the fifth embodiment, by providing either one of the sub-holding unit 152 for holding the sub-liquid accommodating unit 150 and the gas amount adjusting mechanism 153 for adjusting the pressure in the sub-liquid accommodating unit 150, the sub The pressure in the liquid container 150 may be adjusted to the second pressure.

In the fifth embodiment, when the gas amount adjusting mechanism 153 for adjusting the pressure in the sub-liquid accommodating portion 150 is not provided, the sub-liquid accommodating portion 150 is set in the sub-liquid accommodating portion 150 in the same manner as the liquid accommodating portion 15 in FIG. A liquid level detection sensor is provided to detect the liquid level of the liquid in the secondary liquid storage unit 150 in a state of being open to the atmosphere, and the position of the liquid level in the secondary liquid storage unit 150 in the vertical direction Z is from the third position H3. It may be adjusted so as to be within the range of the fourth position H4. For example, when it is detected that the liquid flows into the sub-liquid accommodating portion 150 through the liquid discharge passage 40 by the circulation operation and the position of the liquid surface becomes the third position H3, the control unit 200 sets the third position. 3 Even if the discharge pump is driven until the position of the liquid level reaches the fourth position H4 with the on-off valve 120 closed and the fifth on-off valve 151 and the second on-off valve 89 open. Good. Further, for example, when it is detected that the liquid flows into the sub-liquid accommodating portion 150 through the liquid discharge passage 40 by the circulation operation and the position of the liquid surface becomes the third position H3, the control unit 200 receives the control unit 200. Utilizing the fact that the third on-off valve 120 is in the closed state, the fifth on-off valve 151 is in the open state, and the liquid accommodating portion 15 is arranged below the sub-liquid accommodating portion 150 in the vertical direction Z. The liquid in the sub-liquid accommodating portion 150 may be allowed to flow into the liquid accommodating portion 15, and when it is detected that the position of the liquid surface has reached the fourth position H4, the fifth on-off valve 151 may be closed.

-The degassing of the liquid is not limited to the decompression via the hollow fiber membrane 61, and any method such as ultrasonic degassing or centrifugal degassing can be adopted.
-In the pressure cleaning process, the cap opening valve 101a may be opened instead of releasing the capping in step S21. According to this configuration, the pressure cleaning can be performed while the capping is performed, so that the scattering of the liquid flowing out from the nozzle 21 can be suppressed.

-The recording medium is not limited to the paper 14, and may be a cloth, a plastic film, or a metal film.
-The control unit 200 is configured to be realized by software by a CPU that executes a program, or by hardware by an electronic circuit (for example, a semiconductor integrated circuit) such as an FPGA (field-programmable gate array) or an ASIC (Application Specific IC). It may be realized, or it may be realized by the collaboration of software and hardware.

The liquid discharged by each liquid injection head 20 is not limited to ink, and may be, for example, a liquid material in which particles of a functional material are dispersed or mixed in the liquid. For example, each liquid injection head 20 may discharge a liquid material containing a material such as an electrode material or a pixel material used for manufacturing a liquid crystal display, an electroluminescence display, a surface emitting display, or the like in a dispersed or dissolved form.

The technical idea and its action and effect grasped from the above-described embodiments and modifications are described below.
The liquid injection device includes a liquid injection head having a nozzle surface through which a nozzle for injecting a liquid opens, a liquid supply path connected to a liquid inlet of the liquid injection head and supplying the liquid to the liquid injection head, and the above. It has a liquid discharge path that is connected to the liquid outlet of the liquid injection head and discharges the liquid from the liquid injection head, and a supply-side liquid chamber that is connected to the liquid outlet via the liquid supply path. When the pressure in the supply-side liquid chamber becomes the first pressure lower than the pressure outside the supply-side liquid chamber, the valve is opened to supply the liquid in the supply-side liquid chamber and upstream of the supply-side liquid chamber. A supply-side pressure regulating valve having a supply-side valve body communicating with the path and adjusting the pressure of the liquid supplied to the liquid injection head to a pressure at which a gas-liquid interface formed in the nozzle is maintained. A liquid storage unit connected to the liquid discharge passage, a storage unit pressure adjusting mechanism configured so that the pressure in the liquid storage unit acts on the nozzle through the liquid discharge passage, and the storage unit pressure adjusting mechanism. The pressure in the liquid reservoir adjusted to a second pressure that is lower than the first pressure and maintains the gas-liquid interface formed in the nozzle through the liquid discharge path. A control unit that acts on the nozzle is provided.

According to this configuration, since the liquid injection device has a supply-side pressure adjusting valve on the liquid supply path side that supplies the liquid to the liquid injection head, the nozzle can be adjusted by adjusting the pressure in the liquid storage section connected to the liquid discharge path. The pressure in can be adjusted. Therefore, the liquid injection device can suppress the complicated pressure control when performing the circulation operation of circulating the liquid.

In the liquid injection device, the supply-side pressure adjusting valve comprises a wall portion of the supply-side liquid chamber and bends when the pressure in the supply-side liquid chamber fluctuates, and the supply-side valve body. May have a supply-side urging member that urges the valve to close.

According to this configuration, the liquid injection device can reduce the pressure fluctuation in the supply side liquid chamber by bending the supply side flexible portion, so that the pressure control in the supply side liquid chamber can be facilitated.
In the liquid injection device, the storage unit pressure adjusting mechanism has an on-off valve provided between the liquid injection head and the liquid storage unit in the liquid discharge path, and the control unit has the liquid injection. The on-off valve may be opened when the liquid in the head is discharged to the liquid discharge path side.

According to this configuration, the liquid injection device can easily perform a circulation operation of discharging the liquid in the liquid injection head to the liquid discharge path side by opening and closing the on-off valve.
In the liquid injection device, a pressure damper may be provided between the liquid injection head and the on-off valve in the liquid discharge path.

According to this configuration, the liquid injection device can reduce the pressure fluctuation when opening and closing the on-off valve from acting on the liquid injection head.
In the liquid injection device, the liquid storage unit is connected to the liquid supply path so as to supply the liquid to the liquid injection head, and the liquid stored in the liquid storage unit is connected to the liquid supply path. The liquid storage unit is located at a position where the pressure in the liquid storage unit acting on the nozzle via the liquid discharge path and the liquid flow mechanism that flows toward the supply side pressure regulating valve becomes the second pressure. A holding portion for holding the above may be provided.

According to this configuration, the liquid injection device adjusts the pressure on the liquid supply path side to the first pressure by the pressurized liquid supply path and the supply side pressure adjusting valve, and the pressure on the liquid discharge path side depending on the position of the liquid storage portion. Can be adjusted to a second pressure.

In the liquid injection device, the storage unit pressure adjusting mechanism may adjust the pressure in the liquid storage unit by moving the liquid level of the liquid in the liquid storage unit in the direction of gravity.
According to this configuration, the liquid injection device can easily adjust the pressure on the liquid discharge path side.

The control method of the liquid injection device is a liquid supply path which is connected to a liquid injection head having a nozzle surface through which a nozzle for injecting liquid opens and a liquid inlet of the liquid injection head to supply the liquid to the liquid injection head. And a liquid discharge path connected to the liquid outlet of the liquid injection head to discharge the liquid from the liquid injection head, and a supply side liquid chamber connected to the liquid outlet via the liquid supply path. At the same time, when the pressure in the supply-side liquid chamber becomes the first pressure lower than the pressure outside the supply-side liquid chamber, the valve is opened to be upstream of the supply-side liquid chamber and the supply-side liquid chamber. Supply side pressure adjustment having a supply side valve body communicating with the liquid supply path and adjusting the pressure of the liquid supplied to the liquid injection head to a pressure at which a gas-liquid interface formed in the nozzle is maintained. A method for controlling a liquid injection device including a valve and a liquid storage unit connected to the liquid discharge path, wherein the pressure is lower than the first pressure and the gas-liquid interface formed in the nozzle is not broken. The pressure in the liquid storage unit adjusted to the pressure of 2 is applied to the nozzle through the liquid discharge path, and the liquid in the liquid injection head is discharged to the liquid discharge path side.

According to this method, since the liquid injection device has a supply side pressure adjusting valve on the liquid supply path side for supplying the liquid to the liquid injection head, the nozzle is adjusted by adjusting the pressure in the liquid storage section connected to the liquid discharge path. The pressure in can be adjusted. Therefore, the liquid injection device can suppress the complicated pressure control when performing the circulation operation of circulating the liquid.

In the control method of the liquid injection device, the liquid injection device includes an on-off valve between the liquid injection head and the liquid storage portion in the liquid discharge path, and the liquid in the liquid injection head is referred to as the liquid. The on-off valve is opened when the liquid is discharged to the discharge path side.

According to this method, the liquid injection device can easily perform a circulation operation of discharging the liquid in the liquid injection head to the liquid discharge path side by opening and closing the on-off valve.

11 ... Recording device, 11a ... Liquid injection device, 12 ... Liquid injection unit, 15 ... Liquid storage unit, 15a ... Holding unit, 20 ... Liquid injection head, 21 ... Nozzle, 21a ... Nozzle surface, 22 ... First common liquid chamber , 22a ... Liquid inlet, 22b ... First passage, 23 ... Injection chamber, 24 ... Vibrating plate, 25 ... Actuator, 26 ... Storage chamber, 27 ... Second common liquid chamber, 27a ... Liquid outlet, 27b ... 2nd passage, 30 ... Liquid supply path, 30a ... Upstream liquid supply path, 31 ... Supply side pressure regulating valve, 32 ... Supply side flexible part, 32a ... Supply side inner surface, 32b ... Supply side outer surface, 33 ... Supply Side liquid chamber, 34 ... Supply side communication chamber, 35 ... Supply side valve body, 36 ... Supply side urging member, 40 ... Liquid discharge path, 40a ... Branch, 41 ... Discharge side pressure adjustment valve, 42 ... Discharge side possible Flexible part, 42a ... Discharge side inner surface, 42b ... Discharge side outer surface, 43 ... Discharge side liquid chamber, 43a ... 1st communication hole, 43b ... 2nd communication hole, 43c ... 3rd communication hole, 44 ... 1st discharge side communication Room, 45 ... 2nd discharge side communication chamber, 46 ... Discharge side valve body, 47 ... Discharge side urging member, 50 ... Return flow path, 51 ... 1st on-off valve, 52 ... Flow pump, 70 ... Liquid introduction path, 71 ... 1st switching valve, 72 ... atmospheric communication passage, 72a ... open end, 73 ... bypass flow path, 74 ... 2nd switching valve, 81 ... pressurizing pump, 88 ... discharge pump, 90 ... head holder, 120 ... 3 on-off valve, 121 ... pressure damper, 122 ... flexible part for pressure adjustment, 123 ... pressure adjustment chamber, 124 ... discharge flow pump, 130 ... fourth on-off valve, 140 ... supply side liquid storage part, 141 ... supply side storage Part pressure adjustment mechanism, 141a ... open path to the atmosphere, 141b ... pressure gauge, 141c ... gas discharge pump, 141d ... open to the atmosphere valve, 150 ... sub liquid storage unit, 151 ... fifth on-off valve, 152 ... sub holding part, 153 ... Gas amount adjusting mechanism, 153a ... sub-atmosphere opening path, 153b ... sub-pressure gauge, 153c ... gas amount adjusting pump, 153d ... sub-atmosphere opening valve, 200 ... control unit.

Claims (8)

A liquid injection head having a nozzle surface through which a nozzle for injecting liquid opens,
A liquid supply path that is connected to the liquid inlet of the liquid injection head and supplies the liquid to the liquid injection head.
A liquid discharge path that is connected to the liquid outlet of the liquid injection head and discharges the liquid from the liquid injection head.
When it has a supply-side liquid chamber connected to the liquid outlet via the liquid supply passage, and the pressure in the supply-side liquid chamber becomes a first pressure lower than the pressure outside the supply-side liquid chamber. Has a supply-side valve body that communicates the supply-side liquid chamber and the liquid supply passage on the upstream side of the supply-side liquid chamber, and applies the pressure of the liquid supplied to the liquid injection head. A supply-side pressure regulating valve that adjusts the pressure to maintain the gas-liquid interface formed in the nozzle,
A liquid storage unit connected to the liquid discharge path and
A reservoir pressure adjusting mechanism configured so that the pressure in the liquid reservoir acts on the nozzle through the liquid discharge path.
The pressure in the liquid reservoir is adjusted to a second pressure that is lower than the first pressure and maintains the gas-liquid interface formed in the nozzle by controlling the reservoir pressure adjusting mechanism. A liquid injection device including a control unit that acts on the nozzle via a liquid discharge path. The supply-side pressure adjusting valve constitutes a wall portion of the supply-side liquid chamber and bends when the pressure in the supply-side liquid chamber fluctuates, and the supply-side flexible portion and the supply-side valve body are closed. The liquid injection device according to claim 1, further comprising a supply-side urging member for urging. The storage unit pressure adjusting mechanism has an on-off valve provided between the liquid injection head and the liquid storage unit in the liquid discharge path.
The liquid injection device according to claim 1 or 2, wherein the control unit opens the on-off valve when the liquid in the liquid injection head is discharged to the liquid discharge path side. The liquid injection device according to claim 3, wherein a pressure damper is provided between the liquid injection head and the on-off valve in the liquid discharge path. The liquid storage unit is connected to the liquid supply path so as to supply the liquid to the liquid injection head.
A liquid flow mechanism that causes the liquid stored in the liquid storage unit to flow toward the supply-side pressure regulating valve via the liquid supply path.
Claims 1 to 1 include a holding portion for holding the liquid storage portion at a position where the pressure in the liquid storage portion acting on the nozzle via the liquid discharge path becomes the second pressure. The liquid injection device according to any one of claims 4. Any of claims 1 to 5, wherein the storage unit pressure adjusting mechanism adjusts the pressure in the liquid storage unit by moving the liquid level of the liquid in the liquid storage unit in the direction of gravity. The liquid injection device according to one item. A liquid injection head having a nozzle surface through which a nozzle for injecting liquid opens,
A liquid supply path that is connected to the liquid inlet of the liquid injection head and supplies the liquid to the liquid injection head.
A liquid discharge path that is connected to the liquid outlet of the liquid injection head and discharges the liquid from the liquid injection head.
When it has a supply-side liquid chamber connected to the liquid outlet via the liquid supply passage, and the pressure in the supply-side liquid chamber becomes a first pressure lower than the pressure outside the supply-side liquid chamber. Has a supply-side valve body that communicates the supply-side liquid chamber and the liquid supply passage on the upstream side of the supply-side liquid chamber, and applies the pressure of the liquid supplied to the liquid injection head. A supply-side pressure regulating valve that adjusts the pressure to maintain the gas-liquid interface formed in the nozzle,
A method for controlling a liquid injection device including a liquid storage unit connected to the liquid discharge path.
A pressure in the liquid storage unit adjusted to a second pressure lower than the first pressure and not breaking the gas-liquid interface formed in the nozzle is applied to the nozzle through the liquid discharge path. , A method for controlling a liquid injection device, which comprises discharging the liquid in the liquid injection head to the liquid discharge path side. The liquid injection device includes an on-off valve between the liquid injection head and the liquid storage portion in the liquid discharge path.
The control method for a liquid injection device according to claim 7, wherein the on-off valve is opened when the liquid in the liquid injection head is discharged to the liquid discharge path side.