Liquid discharge device and control method of liquid discharge device

Abstract

To provide a liquid discharge device and a control method of a liquid discharge device which can accurately inspect an atmosphere release valve.SOLUTION: A control method of a liquid discharge device, which includes a discharge part that has a nozzle surface where a nozzle is opened and discharges a liquid from the nozzle, a cap covering the nozzle by being brought into contact with the nozzle surface, a decompression part for decompressing the inside of the cap, a measurement part for measuring the pressure in the cap, an atmosphere open path for making the inside of the cap communicate with the atmosphere, and an atmosphere release valve for opening / closing the atmosphere open path, includes executing open inspection that includes executing control of opening the atmosphere open valve in a state in which the cap is brought into contact with the nozzle surface, then starting the decompression by the decompression part, and determining that the atmosphere open valve is opened when a measurement pressure by the measurement part is equal to or more a threshold after predetermined stand-by time has passed since the decompression by the decompression part started.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a liquid ejection apparatus and a method for controlling the liquid ejection apparatus. [Background technology]

[0002] Patent Document 1 describes a liquid ejection device having a ejection part that ejects liquid, a cap that contacts the ejection part, an air release path that connects the inside of the cap to the atmosphere, and an air release valve located in the air release path. The cap receives the liquid ejected from the ejection part. The liquid ejection device ejects the liquid from the cap by reducing the pressure inside the cap with the cap in contact with the ejection part and the air release valve open. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-30421 Summary of the Invention [Problem to be solved by the invention]

[0004] In such liquid ejection devices, the air release valve is inspected for normal operation by measuring the pressure inside the cap while reducing the pressure inside the cap. If liquid remains in the air release path at this time, it will affect the pressure inside the cap. For example, if liquid remains in the air release path, the negative pressure inside the cap may increase even if the air release valve is open. Therefore, if liquid remains in the air release path, the air release valve may not be inspected correctly. [Means for solving the problem]

[0005] A control method for a liquid ejection device that solves the above problem is a control method for a liquid ejection device that has a nozzle surface through which a nozzle opens and ejects liquid from the nozzle, a cap that covers the nozzle by contacting the nozzle surface, a pressure reduction unit that reduces the pressure inside the cap, a measurement unit that measures the pressure inside the cap, an atmosphere open path that connects the inside of the cap to the atmosphere, and an atmosphere open valve that opens and closes the atmosphere open path, and includes performing an open inspection that includes starting pressure reduction by the pressure reduction unit after executing control to open the atmosphere open valve with the cap in contact with the nozzle surface, and determining that the atmosphere open valve is open if the pressure measured by the measurement unit after a predetermined waiting time has elapsed since the pressure reduction by the pressure reduction unit started is equal to or greater than a threshold value.

[0006] A liquid ejection device that solves the above problem comprises an ejection unit having a nozzle surface through which a nozzle opens and ejecting liquid from the nozzle, a cap that covers the nozzle by contacting the nozzle surface, a pressure reduction unit that reduces the pressure inside the cap, a measurement unit that measures the pressure inside the cap, an atmosphere open path that connects the inside of the cap to the atmosphere, an atmosphere open valve that opens and closes the atmosphere open path, and a control unit, wherein the control unit executes control to open the atmosphere open valve with the cap in contact with the nozzle surface, and then starts reducing pressure by the pressure reduction unit, and executes an open test to determine that the atmosphere open valve is open if the pressure measured by the measurement unit after a predetermined waiting time has elapsed since the pressure reduction by the pressure reduction unit started is equal to or greater than a threshold value. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram showing an embodiment of a liquid ejection device. [Diagram 2] FIG. 2 is a graph showing the change in the measurement pressure during the open / close inspection. [Diagram 3] FIG. 3 is a flowchart showing an example of an open inspection. [Figure 4] FIG. 4 is a flow chart showing an example of a closure test. [Diagram 5]FIG. 5 is a graph showing the progress of the measurement pressure in the wiper inspection. [Figure 6] FIG. 6 is a graph showing the transition of the measured pressure during the discharge process. [Figure 7] FIG. 7 is a graph showing the progress of the measurement pressure in the factor determination test. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] An embodiment of a liquid ejection device will be described below with reference to the drawings. The liquid ejection device is, for example, an inkjet printer that prints images such as characters and photographs by ejecting ink, which is an example of a liquid, onto a medium such as paper or fabric.

[0009] <Liquid discharge device> 1, the liquid ejection device 11 includes an ejection unit 12. The ejection unit 12 is configured to eject liquid. The ejection unit 12 ejects the liquid onto a medium, thereby printing an image on the medium.

[0010] The ejection unit 12 has a nozzle surface 13. One or more nozzles 14 are opened on the nozzle surface 13. The ejection unit 12 ejects liquid from the nozzles 14. In one example, the ejection unit 12 ejects liquid with the nozzle surface 13 in an inclined position oblique to the horizontal. The ejection unit 12 is a line head capable of ejecting liquid simultaneously across the width of the medium. The ejection unit 12 may be a serial head that ejects liquid while scanning the medium.

[0011] The ejection part 12 may be configured to move in a direction perpendicular to the nozzle surface 13. By moving in this direction, the ejection part 12 approaches or moves away from a maintenance part 21, which will be described later. By approaching the maintenance part 21, the ejection part 12 can come into contact with the maintenance part 21.

[0012] The liquid ejection device 11 is configured to allow a liquid container 15 to be detachably attached. The liquid container 15 contains liquid. The liquid container 15 is, for example, an ink cartridge. When the liquid container 15 is attached to the liquid ejection device 11, liquid can be supplied from the liquid container 15 to the ejection unit 12.

[0013] The liquid ejection device 11 includes a connection flow path 16. The connection flow path 16 is connected to the ejection portion 12 and the liquid container 15. Through the connection flow path 16, liquid is supplied from the liquid container 15 to the ejection portion 12.

[0014] The liquid ejection device 11 may include one or more sub-tanks 17. The sub-tanks 17 store liquid. The sub-tanks 17 are located in the connection flow paths 16. The sub-tanks 17 store liquid supplied from the liquid container 15. The liquid ejection device 11 may be configured to circulate the liquid between the sub-tanks 17 and the ejection unit 12. The liquid ejection device 11 may include, for example, a return flow path that returns the liquid from the ejection unit 12 to the sub-tanks 17.

[0015] The liquid ejection device 11 includes a pressurizing unit 18. The pressurizing unit 18 is configured to pressurize the inside of the ejection unit 12. The pressurizing unit 18 is connected to, for example, the sub-tank 17. The pressurizing unit 18 includes, for example, an air pump. In this case, the pressurizing unit 18 pressurizes the inside of the ejection unit 12 by sending air into the sub-tank 17. The ejection unit 12 is cleaned by the pressurizing unit 18 pressurizing the inside of the ejection unit 12. The cleaning will be described later. The liquid may be circulated by the pressurizing unit 18 pressurizing the inside of the ejection unit 12. The pressurizing unit 18 may be a liquid pump located in the connection flow path 16.

[0016] The liquid ejection device 11 includes a maintenance unit 21. The maintenance unit 21 is configured to perform maintenance on the ejection unit 12. For example, the maintenance unit 21 performs maintenance on the ejection unit 12 by receiving liquid discharged from the ejection unit 12 by cleaning. Cleaning is an operation for forcibly discharging liquid from the nozzle 14. Viscous liquid, air bubbles, and the like are discharged from the ejection unit 12 by cleaning.

[0017] The cleaning includes pressure cleaning. Pressure cleaning is an operation for forcibly discharging liquid from the nozzle 14 by pressurizing the inside of the discharge part 12. In one example, the pressure unit 18 pressurizes the inside of the discharge part 12 to perform pressure cleaning.

[0018] The cleaning includes suction cleaning. Suction cleaning is an operation for forcibly discharging liquid from the nozzle 14 by suctioning the inside of the discharge part 12. In one example, the maintenance part 21 performs suction cleaning by suctioning the inside of the discharge part 12.

[0019] The cleaning may include slight pressure cleaning. Slight pressure cleaning is an operation in which the liquid is forcibly discharged from the nozzle 14 by pressurizing the inside of the discharge part 12, similar to the pressurized cleaning. In one example, the slight pressure cleaning is performed by the pressurizing part 18 pressurizing the inside of the discharge part 12. In the slight pressure cleaning, the amount of liquid discharged from the nozzle 14 is smaller than in the pressurized cleaning. Therefore, the cleaning strength in the slight pressure cleaning is smaller than in the pressurized cleaning.

[0020] The cleaning may include circulation cleaning. Similar to pressurized cleaning and slightly pressurized cleaning, circulation cleaning is an operation in which the liquid is circulated by pressurizing the inside of the discharge part 12. In circulation cleaning, pressurization inside the discharge part 12 may cause liquid to leak from the nozzle 14. In this respect, circulation cleaning is an operation in which the liquid is forcibly discharged from the nozzle 14.

[0021] The maintenance unit 21 may perform maintenance on the ejection unit 12 by receiving liquid ejected from the ejection unit 12 by flushing. Flushing is a maintenance in which the ejection unit 12 ejects liquid appropriately from the nozzle 14. Clogging of the nozzle 14 is suppressed by flushing.

[0022] The maintenance unit 21 may perform maintenance on the ejection unit 12 by wiping the ejection unit 12. Wiping is an operation in which the maintenance unit 21 wipes the nozzle surface 13. Liquid, foreign matter, and the like are removed from the nozzle surface 13 by wiping.

[0023] The maintenance part 21 may maintain the ejection part 12 by capping the ejection part 12. Capping is an operation in which the maintenance part 21 comes into contact with the ejection part 12 to form a space communicating with the nozzle 14. The nozzle 14 is kept moist by the capping.

[0024] The maintenance unit 21 has a cap 22. The cap 22 covers the nozzles 14 by contacting the nozzle face 13. That is, the cap 22 performs capping. In addition to capping, the cap 22 maintains the ejection unit 12 by receiving liquid used in cleaning and flushing. The liquid received by cleaning and flushing is accumulated in the cap 22.

[0025] The cap 22 may be configured to move in a direction perpendicular to the nozzle face 13. By moving in this direction, the cap 22 moves closer to or away from the ejection portion 12. By approaching the ejection portion 12, the cap 22 can come into contact with the ejection portion 12.

[0026] The maintenance unit 21 has an atmosphere open path 23. The atmosphere open path 23 is connected to the cap 22. The atmosphere open path 23 is a flow path that connects the inside of the cap 22 to the atmosphere. The atmosphere open path 23 reduces the risk of the pressure inside the cap 22 increasing during capping, for example. If the pressure inside the cap 22 increases due to, for example, an increase in temperature during capping, the meniscus formed in the nozzle 14 may be destroyed. The atmosphere open path 23 may include a thin tube. In this case, the flow path resistance of the atmosphere open path 23 increases. This allows the pressure inside the cap 22 to escape through the atmosphere open path 23, and steam is less likely to be discharged from inside the cap 22, improving the moisture retention ability of the cap 22.

[0027] The maintenance unit 21 has an atmosphere release valve 24. The atmosphere release valve 24 is located in the atmosphere release path 23. The atmosphere release valve 24 opens and closes the atmosphere release path 23. When the atmosphere release valve 24 is opened, the inside of the cap 22 communicates with the atmosphere through the atmosphere release path 23. The atmosphere release valve 24 is, for example, a solenoid valve.

[0028] The maintenance unit 21 may have a wiper 25. The wiper 25 wipes the nozzle surface 13 by coming into contact with the nozzle surface 13. In other words, the wiper 25 performs wiping.

[0029] The wiper 25 has a blade 26 that comes into contact with the nozzle surface 13, and a holder 27 that holds the blade 26. The wiper 25 wipes the nozzle surface 13 by moving in the longitudinal direction of the ejection section 12 while in contact with the nozzle surface 13. The nozzle surface 13 may be wiped by the ejection section 12 moving relative to the wiper 25. Liquid wiped away by wiping accumulates on the wiper 25. More specifically, liquid flows from the nozzle surface 13 down the blade 26 and accumulates in the holder 27.

[0030] The wiper 25 may be configured to move in a direction perpendicular to the nozzle face 13. By moving in this direction, the wiper 25 moves closer to and away from the ejection portion 12. By approaching the ejection portion 12, the wiper 25 can come into contact with the ejection portion 12.

[0031] The maintenance unit 21 has a pressure reducing unit 28. The pressure reducing unit 28 is configured to reduce the pressure inside the cap 22. The pressure reducing unit 28 is connected to the cap 22. In one example, the pressure reducing unit 28 is configured to reduce the pressure not only of the cap 22 but also of the wiper 25. The pressure reducing unit 28 is connected to the wiper 25.

[0032] The pressure reduction unit 28 has one or more pressure reduction paths. In one example, the pressure reduction unit 28 has two pressure reduction paths. More specifically, the pressure reduction unit 28 has a cap pressure reduction path 29 and a wiper pressure reduction path 30. The pressure reduction paths are flow paths to which negative pressure acts. The cap pressure reduction path 29 is connected to the cap 22. The inside of the cap 22 is reduced in pressure through the cap pressure reduction path 29. The wiper pressure reduction path 30 is connected to the wiper 25. More specifically, the wiper pressure reduction path 30 is connected to the holder 27. The inside of the holder 27 is reduced in pressure through the wiper pressure reduction path 30.

[0033] The pressure reducing unit 28 has a buffer 31. The buffer 31 is connected to the pressure reducing passage. In one example, the buffer 31 is connected to the cap pressure reducing passage 29 and the wiper pressure reducing passage 30. The pressure in the buffer 31 acts on the cap 22 through the cap pressure reducing passage 29. The pressure of the buffer 31 acts on the wiper 25 through the wiper pressure reducing passage 30. In more detail, the pressure of the buffer 31 acts on the holder 27 through the wiper pressure reducing passage 30.

[0034] The buffer 31 stores the liquid collected from the discharge portion 12 through the decompression path. The buffer 31 stores the liquid received by the cap 22 through the cap decompression path 29. The buffer 31 stores the liquid wiped by the wiper 25 through the wiper decompression path 30.

[0035] The pressure reducing unit 28 has one or more on-off valves. In one example, the pressure reducing unit 28 has two on-off valves. More specifically, the pressure reducing unit 28 has a cap on-off valve 32 and a wiper on-off valve 33. The on-off valves are located in the pressure reducing passages. The on-off valves open and close the pressure reducing passages. The cap on-off valve 32 is located in the cap pressure reducing passage 29. The cap on-off valve 32 opens and closes the cap pressure reducing passage 29. When the cap on-off valve 32 is open, the cap 22 and the buffer 31 communicate with each other through the cap pressure reducing passage 29. The wiper on-off valve 33 is located in the wiper pressure reducing passage 30. The wiper on-off valve 33 opens and closes the wiper pressure reducing passage 30. When the wiper on-off valve 33 is open, the wiper 25 and the buffer 31 communicate with each other through the wiper pressure reducing passage 30.

[0036] The pressure reducing unit 28 has a pressure reducing pump 34. The pressure reducing pump 34 is configured to reduce the pressure inside the cap 22. In one example, the pressure reducing pump 34 is connected to the buffer 31. The pressure reducing pump 34 reduces the pressure inside the cap 22 by reducing the pressure inside the buffer 31. The pressure reducing pump 34 reduces the pressure inside the cap 22 through the buffer 31 and the cap pressure reducing passage 29. The pressure reducing pump 34 may be directly connected to the cap 22 or may be directly connected to the cap pressure reducing passage 29. The pressure reducing pump 34 is, for example, an air pump.

[0037] The pressure reducing unit 28 performs suction cleaning by reducing the pressure inside the cap 22 with the pressure reducing pump 34. More specifically, the pressure reducing unit 28 performs suction cleaning by reducing the pressure inside the cap 22 with the cap 22 in contact with the nozzle surface 13 and the air release valve 24 closed. With the cap 22 in contact with the nozzle surface 13 and the air release valve 24 closed, the inside of the cap 22 is not connected to the atmosphere. Therefore, the pressure reducing pump 34 reduces the pressure inside the cap 22, and the negative pressure inside the cap 22 acts on the nozzle 14. As a result, the liquid is discharged from the nozzle 14. In one example, in suction cleaning, the pressure reducing unit 28 first reduces the pressure inside the buffer 31 with the cap opening / closing valve 32 closed by the pressure reducing pump 34. Next, the pressure reducing unit 28 opens the cap opening / closing valve 32. As a result, the negative pressure inside the buffer 31 acts on the cap 22. In this way, the pressure reducing unit 28 performs suction cleaning.

[0038] The pressure reducing unit 28 performs the empty suction by reducing the pressure inside the cap 22 with the pressure reducing pump 34. More specifically, the pressure reducing unit 28 performs the empty suction by reducing the pressure inside the cap 22 with the cap 22 in contact with the nozzle surface 13 and the atmosphere release valve 24 open. The empty suction is an operation for discharging liquid from the cap 22. With the cap 22 in contact with the nozzle surface 13 and the atmosphere release valve 24 open, the inside of the cap 22 communicates with the atmosphere through the atmosphere release path 23. Therefore, the atmosphere is drawn into the cap 22 through the atmosphere release path 23 by the pressure reducing pump 34 reducing the pressure inside the cap 22. As a result, the liquid is discharged from the cap 22. In one example, in the empty suction, the pressure reducing unit 28 first reduces the pressure inside the buffer 31 with the pressure reducing pump 34 with the cap opening / closing valve 32 closed. Next, the pressure reducing unit 28 opens the cap opening / closing valve 32. As a result, the negative pressure inside the buffer 31 acts on the inside of the cap 22. In this manner, the decompression unit 28 performs dry suction.

[0039] The vacuum pump 34 may be configured to reduce the pressure inside the holder 27. In one example, the vacuum pump 34 reduces the pressure inside the holder 27 by reducing the pressure inside the buffer 31. The vacuum pump 34 reduces the pressure inside the holder 27 through the buffer 31 and the wiper vacuum path 30. The vacuum pump 34 may be directly connected to the holder 27 or directly connected to the wiper vacuum path 30.

[0040] The pressure reducing unit 28 exhausts the liquid from the holder 27 by reducing the pressure inside the holder 27 with the pressure reducing pump 34. Since the inside of the holder 27 is always open to the atmosphere, the pressure reducing pump 34 reduces the pressure inside the holder 27, drawing the atmosphere into the holder 27. This exhausts the liquid from the holder 27. In one example, the pressure reducing unit 28 first reduces the pressure inside the buffer 31 with the pressure reducing pump 34 while the wiper opening / closing valve 33 is closed. Next, the pressure reducing unit 28 opens the wiper opening / closing valve 33. This causes the negative pressure in the buffer 31 to act on the inside of the holder 27. In this manner, the pressure reducing unit 28 exhausts the liquid from the holder 27.

[0041] The decompression unit 28 is not limited to reducing the pressure inside the buffer 31, and may be configured to pressurize the buffer 31. The decompression unit 28 pressurizes the buffer 31, thereby discharging liquid from the buffer 31. In one example, the decompression unit 28 has a decompression flow path 35 and a pressurization flow path 36. The decompression flow path 35 is connected to the buffer 31 and the decompression pump 34. The pressurization flow path 36 is connected to the buffer 31 and the decompression pump 34. The decompression pump 34 draws air from the decompression flow path 35. The decompression pump 34 exhausts air to the pressurization flow path 36. Therefore, the decompression unit 28 can reduce the pressure inside the buffer 31 through the decompression flow path 35. The decompression unit 28 can pressurize the buffer 31 through the pressurization flow path 36.

[0042] The pressure reduction unit 28 has a pressure reduction flow path valve 37 and a pressure reduction flow path valve 38. The pressure reduction flow path valve 37 is located in the pressure reduction flow path 35. The pressure reduction flow path valve 37 opens and closes the pressure reduction flow path 35. When the pressure reduction flow path valve 37 is open, the buffer 31 and the pressure reduction pump 34 communicate with each other through the pressure reduction flow path 35. The pressure reduction flow path valve 38 is located in the pressure reduction flow path 36. The pressure reduction flow path valve 38 opens and closes the pressure reduction flow path 36. When the pressure reduction flow path valve 38 is open, the buffer 31 and the pressure reduction pump 34 communicate with each other through the pressure reduction flow path 36.

[0043] The pressure reduction section 28 has a pressure reduction release path 39 and a pressure reduction release path 40. The pressure reduction release path 39 is connected to the pressure reduction flow path 35. More specifically, the pressure reduction release path 39 is connected in the pressure reduction flow path 35 between the pressure reduction pump 34 and the pressure reduction flow path valve 37. The pressure reduction release path 39 connects the pressure reduction flow path 35 to the atmosphere. The pressure reduction release path 40 is connected to the pressure reduction flow path 36. More specifically, the pressure reduction release path 40 is connected in the pressure reduction flow path 36 between the pressure reduction pump 34 and the pressure reduction flow path valve 38. The pressure reduction release path 40 connects the pressure reduction flow path 36 to the atmosphere.

[0044] The pressure reduction section 28 has a pressure reduction release valve 41 and a pressurization release valve 42. The pressure reduction release valve 41 is located in the pressure reduction release path 39. The pressure reduction release valve 41 opens and closes the pressure reduction release path 39. When the pressure reduction release valve 41 opens, the pressure reduction flow path 35 is opened to the atmosphere. The pressurization release valve 42 is located in the pressurization release path 40. The pressurization release valve 42 opens and closes the pressurization release path 40. When the pressurization release valve 42 opens, the pressurization flow path 36 is opened to the atmosphere.

[0045] The pressure reducing unit 28 reduces the pressure inside the buffer 31 through the pressure reducing flow path 35 by driving the pressure reducing pump 34 with the pressure reducing flow path valve 38 and the pressure reducing release valve 41 closed and with the pressure reducing flow path valve 37 and the pressure reducing release valve 42 open. The pressure reducing unit 28 pressurizes the inside of the buffer 31 through the pressure reducing flow path 36 by driving the pressure reducing pump 34 with the pressure reducing flow path valve 37 and the pressure reducing release valve 42 closed and with the pressure reducing flow path valve 38 and the pressure reducing release valve 41 open.

[0046] The pressure reducing unit 28 has a discharge flow path 43. The discharge flow path 43 is connected to the buffer 31. The discharge flow path 43 is a flow path through which liquid discharged from the buffer 31 flows. The pressure reducing pump 34 pressurizes the inside of the buffer 31, whereby the liquid is discharged from the buffer 31 through the discharge flow path 43.

[0047] The pressure reducing unit 28 has a discharge valve 44. The discharge valve 44 is located in the discharge flow path 43. The discharge valve 44 opens and closes the discharge flow path 43. When the discharge valve 44 is opened, liquid can be discharged from the buffer 31 through the discharge flow path 43.

[0048] The maintenance unit 21 has a maintenance box 45. The maintenance box 45 is connected to the discharge flow path 43. The maintenance box 45 stores the liquid discharged from the buffer 31.

[0049] The maintenance box 45 has a moisture-permeable membrane 46. The moisture-permeable membrane 46 is a membrane that restricts the passage of liquid while allowing the passage of gas. The moisture-permeable membrane 46 allows the inside of the maintenance box 45 to communicate with the atmosphere. By allowing the inside of the maintenance box 45 to communicate with the atmosphere, liquid can be discharged from the buffer 31 to the maintenance box 45.

[0050] The maintenance box 45 may have an absorbent material 47. The absorbent material 47 is configured to absorb liquid. The absorbent material 47 is made of, for example, a foam material. The absorbent material 47 absorbs liquid, allowing the maintenance box 45 to effectively retain the liquid.

[0051] The maintenance unit 21 has a measurement unit 48. The measurement unit 48 is configured to measure the pressure in the cap 22. In one example, the measurement unit 48 is connected to the buffer 31. The measurement unit 48 measures the pressure in the cap 22 through the buffer 31 and the cap decompression path 29. The measurement unit 48 may be directly connected to the cap 22, or may be directly connected to the cap decompression path 29. The measurement unit 48 includes, for example, a pressure sensor. The decompression unit 28 is controlled based on the pressure measured by the measurement unit 48.

[0052] The measuring unit 48 may be configured to measure the pressure in the holder 27, not limited to the pressure in the cap 22. In one example, the measuring unit 48 measures the pressure in the holder 27 through the buffer 31 and the wiper pressure reduction path 30. The measuring unit 48 may be directly connected to the holder 27, or may be directly connected to the wiper pressure reduction path 30.

[0053] The liquid ejection device 11 includes a control unit 50. The control unit 50 controls various components of the liquid ejection device 11. The control unit 50 controls the ejection unit 12, the pressurizing unit 18, and the maintenance unit 21. The control unit 50 may be configured with one or more processors that execute various processes according to a computer program. The control unit 50 may be configured with one or more dedicated hardware circuits, such as an ASIC, that execute at least a part of the various processes. The control unit 50 may be configured with a circuit that includes a combination of a processor and a hardware circuit. The processor includes a CPU and a memory, such as a RAM and a ROM. The memory stores program code or instructions that are configured to cause the CPU to execute a process. The memory, i.e., a computer-readable medium, includes any readable medium that can be accessed by a general-purpose or dedicated computer.

[0054] <Control of liquid ejection device> Next, the control of the liquid ejection device 11 by the control unit 50 will be described. The control unit 50 controls the liquid discharge device 11 according to the program code or instructions. The control unit 50 executes an open / close inspection. The open / close inspection is a process for inspecting whether the atmosphere release valve 24 operates normally. If the atmosphere release valve 24 does not operate normally, liquid may leak. For example, if the atmosphere release valve 24 does not operate while closed, liquid may not be properly discharged from the cap 22, and liquid may leak from the cap 22. In cleaning, the cap 22 receives a large amount of liquid. Therefore, in one example, the control unit 50 executes an open / close inspection before cleaning. Note that if the atmosphere release valve 24 does not operate while open, suction cleaning may not be properly performed, and maintenance of the discharge unit 12 may not be possible.

[0055] The open / close test includes an open test and a closed test. The open test is a test to determine whether the atmospheric release valve 24 is open. The closed test is a test to determine whether the atmospheric release valve 24 is closed. In the open test, the control unit 50 determines whether the atmospheric release valve 24 is open based on the pressure measured by the measurement unit 48. In the closed test, the control unit 50 determines whether the atmospheric release valve 24 is closed based on the pressure measured by the measurement unit 48. If the control unit 50 determines that the atmospheric release valve 24 is open in the open test and determines that the atmospheric release valve 24 is closed in the closed test, the control unit 50 determines that the atmospheric release valve 24 is operating normally.

[0056] The control unit 50 executes the closed test after the open test. In one example, the control unit 50 executes the closed test immediately after the open test. The control unit 50 may execute the closed test with an interval after the open test.

[0057] In the open inspection, the control unit 50 executes control to open the atmosphere release valve 24 with the cap 22 in contact with the nozzle surface 13. Thereafter, the control unit 50 starts depressurization by the depressurization unit 28. The control unit 50 determines that the atmosphere release valve 24 is open when the pressure measured by the measurement unit 48 is equal to or greater than a predetermined value. In other words, the control unit 50 determines that the inside of the cap 22 is in communication with the atmosphere through the atmosphere release path 23.

[0058] In the closing test, the control unit 50 executes control to close the atmosphere release valve 24 with the cap 22 in contact with the nozzle surface 13, and executes decompression by the decompression unit 28. At this time, the decompression by the decompression unit 28 may be continued from the opening test, or may be started again in the closing test. The control unit 50 determines that the atmosphere release valve 24 is closed when the pressure measured by the measurement unit 48 is equal to or lower than a predetermined value. In other words, the control unit 50 determines that the inside of the cap 22 is sealed.

[0059] In the maintenance unit 21, when the cap 22 receives liquid, liquid may adhere to the atmosphere release path 23. Therefore, liquid may remain in the atmosphere release path 23 during the open / close inspection. If liquid remains in the atmosphere release path 23, it may affect the pressure measured by the measurement unit 48 during the open / close inspection. For example, if liquid remains in the atmosphere release path 23, air may not flow easily from the atmosphere release path 23 into the cap 22. In this case, even if the atmosphere release valve 24 is open, the measured pressure by the measurement unit 48 may be less than a predetermined value, and it may be determined that the atmosphere release valve 24 is closed. In one example, the same risk may occur when liquid remains in the cap decompression path 29. If liquid remains in the cap decompression path 29, it may be less likely for liquid and air to flow from the inside of the cap 22 into the buffer 31. Therefore, even if the atmosphere release valve 24 is open, the measured pressure by the measurement unit 48 may be less than a predetermined value, and it may be determined that the atmosphere release valve 24 is closed.

[0060] The liquid remaining in the atmosphere open path 23 moves from the atmosphere open path 23 to the cap 22 as the pressure reduction by the pressure reduction unit 28 continues. That is, the liquid is discharged from the atmosphere open path 23 as the pressure reduction by the pressure reduction unit 28 continues. When the liquid is discharged from the atmosphere open path 23, the negative pressure in the cap 22 decreases, that is, the pressure in the cap 22 increases. Similarly, the liquid remaining in the cap pressure reduction path 29 moves from the cap pressure reduction path 29 to the buffer 31 as the pressure reduction by the pressure reduction unit 28 continues. That is, the liquid is discharged from the cap pressure reduction path 29 as the pressure reduction by the pressure reduction unit 28 continues. When the liquid is discharged from the cap pressure reduction path 29, the negative pressure in the buffer 31 decreases, that is, the pressure in the buffer 31 increases. In this way, when the pressure reduction by the pressure reduction unit 28 continues, the liquid remaining in the atmosphere open path 23, the cap pressure reduction path 29, etc. is discharged. This allows the measurement unit 48 to correctly measure the pressure in the cap 22.

[0061] The control unit 50 determines that the atmosphere release valve 24 is open when the pressure measured by the measurement unit 48 after a predetermined waiting time has elapsed since the start of depressurization by the depressurization unit 28 in the open inspection is equal to or greater than the first threshold value. This allows the control unit 50 to determine whether the atmosphere release valve 24 is open in a state in which the influence of the remaining liquid is reduced.

[0062] The first threshold value is a possible pressure value when it is expected that no liquid remains in the atmosphere open path 23, the cap decompression path 29, etc. For example, the first threshold value is the minimum value of the measured pressure when decompression is performed by the decompression unit 28 with the atmosphere release valve 24 open when no liquid remains in the atmosphere open path 23, the cap decompression path 29, etc. The first threshold value can also be said to be the peak value of the negative pressure when the decompression unit 28 decompresses the inside of the cap 22 when no liquid remains in the atmosphere open path 23, the cap decompression path 29, etc.

[0063] The waiting time is the time during which the liquid remaining in the atmosphere release path 23, the cap decompression path 29, etc. is expected to move. When the remaining liquid starts to move, the pressure measured by the measurement unit 48 starts to increase. In other words, the waiting time is a time longer than the time during which the pressure measured by the measurement unit 48 reaches its minimum value. It can also be said that the waiting time is a time longer than the time during which the negative pressure measured by the measurement unit 48 reaches its peak value.

[0064] As shown in FIG. 2, when liquid remains in the atmosphere release path 23, the cap pressure reduction path 29, etc., during the open inspection, when the pressure reduction by the pressure reduction unit 28 starts, the measured pressure starts to decrease. When the pressure reduction by the pressure reduction unit 28 continues, the measured pressure starts to increase. The measured pressure reaches a peak negative pressure value just before it starts to increase. The time required for the measured pressure to reach a peak negative pressure value varies depending on the amount of liquid remaining in the atmosphere release path 23, the cap pressure reduction path 29, etc. The larger the amount of remaining liquid, the longer the time required for the measured pressure to reach a peak negative pressure value. The waiting time is set, for example, to a time longer than the maximum value of the time required for the measured pressure to reach a peak negative pressure value. This makes it possible to determine whether the atmosphere release valve 24 is open based on the measured pressure after exceeding the peak negative pressure value, regardless of the amount of liquid remaining in the atmosphere release path 23.

[0065] The control unit 50 continues depressurization by the depressurization unit 28 even after determining that the atmosphere release valve 24 is open in the open test. In particular, the control unit 50 continues depressurization by the depressurization unit 28 for a continuous period of time after determining that the atmosphere release valve 24 is open in the open test. This causes the liquid remaining in the atmosphere release path 23 and the liquid remaining in the cap 22 to be discharged. In other words, the next close test can be performed in a state in which the influence of the liquid remaining in the atmosphere release path 23 has been reduced.

[0066] The duration is a time sufficient to drain the liquid from the atmosphere open path 23 and the cap 22. The duration may be longer or shorter than the waiting time. The duration may be the same as the waiting time. The time required to drain the liquid from the atmosphere open path 23 and the cap 22 varies depending on the amount of liquid remaining in the atmosphere open path 23 and the cap 22. The greater the amount of liquid remaining in the atmosphere open path 23 and the cap 22, the longer this time will be. The duration is set, for example, to a time longer than the maximum time required to drain the liquid from the atmosphere open path 23 and the cap 22. This allows the liquid to be drained from the atmosphere open path 23 and the cap 22 regardless of the amount of liquid remaining in the atmosphere open path 23 and the cap 22.

[0067] The control unit 50 determines that the atmosphere release valve 24 is closed when the pressure measured by the measurement unit 48 is equal to or lower than the second threshold value in the closing test. By executing the closing test after the opening test, the control unit 50 can determine whether the atmosphere release valve 24 is closed in a state in which the influence of remaining liquid is reduced. The control unit 50 stops the pressure reducing unit 28 when it determines that the atmosphere release valve 24 is closed in the closing test.

[0068] The second threshold value is a pressure value that can be assumed when the inside of the cap 22 is expected to be sealed. For example, the second threshold value is a pressure value required to perform suction cleaning. The second threshold value may be the same as the first threshold value or may be different.

[0069] Next, an example of a flowchart for the open inspection will be described. As shown in FIG. 3, the control unit 50 opens the cap opening / closing valve 32 in step S11.

[0070] The control unit 50 brings the cap 22 into contact with the nozzle surface 13 in step S12. In step S13, the control unit 50 executes an operation to open the atmosphere release valve 24. At this time, the control unit 50 transmits an open signal to the atmosphere release valve 24 to cause the atmosphere release valve 24 to open.

[0071] In step S14, the control unit 50 starts decompression by the decompression unit 28. At this time, the control unit 50 decompresses the inside of the buffer 31 by the decompression pump 34. In step S15, the control unit 50 waits for the waiting time. At this time, the decompression by the decompression unit 28 continues for the waiting time. As a result, liquid remaining in the atmosphere release path 23, the cap decompression path 29, etc. starts to be discharged.

[0072] In step S16, the control unit 50 acquires the pressure measured by the measurement unit 48. That is, the control unit 50 acquires the pressure measured in a state in which the influence of the remaining liquid has been reduced. In step S17, the control unit 50 determines whether the measured pressure is equal to or greater than the first threshold. If the measured pressure is equal to or greater than the first threshold, the control unit 50 shifts the process to step S18. If the measured pressure is less than the first threshold, the control unit 50 returns the process to step S16. If the process does not shift to step S18 even after repeating the processes of steps S16 and S17 multiple times, the control unit 50 may report an error.

[0073] In step S18, the control unit 50 waits for the duration. At this time, the decompression by the decompression unit 28 continues for the duration. This causes liquid to be discharged from the atmosphere release path 23 and the cap 22. When the control unit 50 finishes the process of step S18, it ends the open inspection.

[0074] When the control unit 50 executes a closed test immediately after the open test, the control unit 50 may continue the depressurization by the depressurization unit 28. That is, the control unit 50 may continue the depressurization by the depressurization unit 28 that was started in the open test throughout the closed test. In this case, the time required for the closed test is shortened compared to the case where the depressurization unit 28 is stopped between the open test and the closed test. When the control unit 50 starts a closed test with an interval after finishing the open test, the control unit 50 may end the depressurization by the depressurization unit 28 at the same time as ending the open test.

[0075] Next, a flowchart of the closure test will be described. 4, in step S21, the control unit 50 opens the cap opening / closing valve 32. When a close test is executed successively after the open test, the cap opening / closing valve 32 remains open.

[0076] In step S22, the control unit 50 brings the cap 22 into contact with the nozzle surface 13. When a closed test is executed successively after the open test, the cap 22 remains in contact with the nozzle surface 13.

[0077] In step S23, the control unit 50 executes an operation to close the atmosphere release valve 24. At this time, the control unit 50 transmits a closing signal to the atmosphere release valve 24 to close the atmosphere release valve 24.

[0078] In step S24, the control unit 50 executes decompression by the decompression unit 28. At this time, the control unit 50 decompresses the inside of the buffer 31 by the decompression pump 34. When a closed test is performed immediately after the open test, the control unit 50 continues decompressing the inside of the cap 22 by the decompression unit 28 from step S14. When a closed test is performed with an interval after the open test, the control unit 50 starts decompression by the decompression unit 28.

[0079] The control unit 50 acquires the pressure measured by the measurement unit 48 in step S25. In step S26, the control unit 50 determines whether the measured pressure is equal to or less than the second threshold. If the measured pressure is equal to or less than the second threshold, the control unit 50 shifts the process to step S27. If the measured pressure is greater than the second threshold, the control unit 50 returns the process to step S25. If the process does not shift to step S27 even after repeating the processes of steps S25 and S26 multiple times, the control unit 50 may notify an error.

[0080] The control unit 50 stops the pressure reducing unit 28 in step S27. In step S28, the control unit 50 executes an operation to open the atmosphere release valve 24. At this time, the control unit 50 transmits an open signal to the atmosphere release valve 24. When the atmosphere release valve 24 opens, the negative pressure in the cap 22 is released. When the control unit 50 finishes the process of step S28, it ends the closure test. When the closure test ends, the open / close test ends.

[0081] Next, the wiper inspection will be described. The control unit 50 may execute a wiper inspection. The wiper inspection is an inspection to determine whether liquid is normally discharged from the wiper 25. In the maintenance unit 21, if the wiper pressure reduction path 30 is choked, liquid may not be discharged from the holder 27. For example, if a foreign object enters the wiper pressure reduction path 30 or if the wiper pressure reduction path 30 is bent, the wiper pressure reduction path 30 will be choked. In this case, liquid may leak from the holder 27. The wiper inspection can also be said to be an inspection to determine whether the wiper pressure reduction path 30 is choked.

[0082] In the wiper inspection, the control unit 50 executes decompression by the decompression unit 28. At this time, the control unit 50 decompresses the buffer 31, thereby decompressing the holder 27. Thereafter, the control unit 50 judges whether the pressure measured by the measurement unit 48 is equal to or lower than the choke threshold. If the measured pressure is equal to or lower than the choke threshold, the control unit 50 judges that the wiper decompression path 30 is choked. The choke threshold is the measured pressure at which it is expected that liquid will not be normally discharged from the wiper 25. If the measured pressure is equal to or lower than the choke threshold, the control unit 50 judges that negative pressure is not acting inside the holder 27.

[0083] As shown in Fig. 5, when the wiper pressure reduction passage 30 is choked, the pressure measured by the measuring unit 48 is smaller than when the wiper pressure reduction passage 30 is not choked. The graph shown by the two-dot chain line in Fig. 5 is the pressure measured when the wiper pressure reduction passage 30 is choked. The graph shown by the solid line in Fig. 5 is the pressure measured when the wiper pressure reduction passage 30 is not choked.

[0084] Next, the discharge process will be described. The control unit 50 may execute a discharge process. The discharge process is a process of discharging liquid from the buffer 31. The discharge process can also be said to be a process of causing liquid to flow from the buffer 31 to the maintenance box 45. The control unit 50 executes the discharge process at a predetermined timing. In the discharge process, the control unit 50 executes pressurization of the inside of the buffer 31 by the decompression unit 28. In the discharge process, the control unit 50 controls the pressurization by the decompression unit 28 based on the pressure measured by the measurement unit 48.

[0085] 6, in the discharge process, the control unit 50 pressurizes the inside of the buffer 31 so that the measured pressure does not exceed the allowable threshold value. This is to prevent the pressure inside the buffer 31 from exceeding the withstand pressure of the discharge flow path 43, the maintenance box 45, etc.

[0086] In the discharge process, the control unit 50 judges whether the measured pressure at the remaining amount judgment time is equal to or greater than the remaining amount judgment threshold. In detail, the control unit 50 judges whether the measured pressure after the remaining amount judgment time has elapsed since the pressure reduction unit 28 started pressurizing is equal to or greater than the remaining amount judgment threshold. When the measured pressure is equal to or greater than the remaining amount judgment threshold, the control unit 50 judges that there is liquid in the buffer 31. When the measured pressure is less than the remaining amount judgment threshold, the control unit 50 judges that there is no liquid in the buffer 31 or that there is only a small amount of liquid in the buffer 31. When there is liquid in the buffer 31, the measured pressure is likely to increase as the pressure reduction unit 28 pressurizes the buffer 31. That is, the degree of increase in the measured pressure differs depending on whether there is liquid in the buffer 31. Therefore, the control unit 50 can judge whether there is liquid in the buffer 31 based on the remaining amount judgment threshold.

[0087] The graph shown by the solid line in Fig. 6 shows the transition when the measured pressure at the remaining amount determination time is equal to or greater than the remaining amount determination threshold. The graphs shown by the dashed dotted line and the dashed two dotted line in Fig. 6 show the transition when the measured pressure at the remaining amount determination time is less than the remaining amount determination threshold. The graph shown by the dashed dotted line in Fig. 6 shows the transition when there is very little liquid in the buffer 31. The graph shown by the dashed two dotted line in Fig. 6 shows the transition when there is no liquid in the buffer 31.

[0088] When the control unit 50 determines that there is no liquid in the buffer 31 or that the amount of liquid in the buffer 31 is small, the control unit 50 continues pressurization by the decompression unit 28 for a certain period of time and then stops the decompression unit 28. Thereafter, the control unit 50 ends the discharge process.

[0089] When the control unit 50 determines that there is liquid in the buffer 31, it causes the liquid to be discharged from the buffer 31. More specifically, the control unit 50 pressurizes the inside of the buffer 31 until the measured pressure falls below the abnormality determination threshold. When the liquid is discharged by pressurizing the buffer 31, the measured pressure decreases as the liquid is discharged. When the measured pressure falls below the abnormality determination threshold, the control unit 50 determines that the liquid is being discharged normally.

[0090] When the control unit 50 determines that there is liquid in the buffer 31 and when the measured pressure at the abnormality determination time is equal to or greater than the abnormality determination threshold, it determines that the liquid is not being discharged normally. In this case, the control unit 50 executes a cause determination test.

[0091] The cause determination test is a test to determine the cause of the liquid not being discharged normally. In the maintenance unit 21, if an abnormality occurs in the discharge flow path 43 or the maintenance box 45, it may become impossible to discharge the liquid from the buffer 31. If the discharge flow path 43 is choked, it becomes impossible to discharge the liquid from inside the buffer 31 to the maintenance box 45. If the moisture permeable membrane 46 becomes wet with the liquid, it becomes impossible to discharge the liquid from inside the buffer 31 to the maintenance box 45. The cause determination test can also be said to be a test to determine whether the abnormality occurs in the discharge flow path 43 or the maintenance box 45.

[0092] As shown in Fig. 7, the control unit 50 pressurizes the buffer 31 in the factor determination test. Thereafter, the control unit 50 determines whether the measured pressure at the factor determination time is equal to or greater than the factor determination threshold. More specifically, the control unit 50 determines whether the measured pressure after the factor determination time has elapsed since the start of pressurization in the buffer 31 is equal to or greater than the factor determination threshold. If the measured pressure is equal to or greater than the factor determination threshold, the control unit 50 determines that an abnormality has occurred in the discharge flow path 43. If the measured pressure is less than the factor determination threshold, the control unit 50 determines that an abnormality has occurred in the maintenance box 45.

[0093] The graph shown by the solid line in Fig. 7 shows the transition when an abnormality occurs in the discharge flow path 43. The graph shown by the dashed dotted line in Fig. 7 shows the transition when an abnormality occurs in the maintenance box 45. When an abnormality occurs in the discharge flow path 43, the pressure in the buffer 31 is more likely to increase than when an abnormality occurs in the maintenance box 45. This is because when an abnormality occurs in the discharge flow path 43, it is more difficult for liquid and air to flow from the buffer 31 into the maintenance box 45 than when an abnormality occurs in the maintenance box 45.

[0094] The control unit 50 may notify the user of the cause of the discharge failure, so that the user can know whether the discharge flow path 43 or the maintenance box 45 should be replaced.

[0095] <Action and Effects> Next, the operation and effects of the above embodiment will be described. (1) The control method of the liquid ejection device 11 includes executing an open inspection. The open inspection includes starting depressurization in the cap 22 by the pressure reducing unit 28 after executing control to open the atmosphere release valve 24 with the cap 22 in contact with the nozzle surface 13, and determining that the atmosphere release valve 24 is open when the pressure measured by the measurement unit 48 after a predetermined waiting time has elapsed since the start of depressurization by the pressure reducing unit 28. When the pressure reducing unit 28 reduces the pressure in the cap 22 with the cap 22 in contact with the nozzle surface 13 and the atmosphere release valve 24 open, air flows into the cap 22 through the atmosphere release path 23. At this time, if liquid remains in the atmosphere release path 23, air is less likely to flow into the cap 22. That is, if liquid remains in the atmosphere release path 23, the negative pressure in the cap 22 increases due to the pressure reduction by the pressure reducing unit 28. Therefore, even if the atmosphere release valve 24 is open, the negative pressure in the cap 22 is large, so that it may be determined that the atmosphere release valve 24 is closed. According to the above method, the pressure reduction by the pressure reduction unit 28 continues for the waiting time, so that the liquid remaining in the atmosphere open path 23 is sucked. Therefore, the negative pressure inside the cap 22 decreases as the waiting time passes from the start of pressure reduction by the pressure reduction unit 28. In other words, the pressure inside the cap 22 can be measured in a state where the influence of the liquid remaining in the atmosphere open path 23 is reduced as the waiting time passes from the start of pressure reduction by the pressure reduction unit 28. This allows the atmosphere open valve 24 to be properly inspected.

[0096] (2) The control method of the liquid ejection device 11 includes continuing the decompression by the decompression unit 28 even after it is determined in the open inspection that the atmosphere release valve 24 is open. According to the above method, liquid remaining in the atmosphere release path 23 is easily discharged.

[0097] (3) The control method of the liquid discharger 11 includes continuing the decompression by the decompression unit 28 for a predetermined duration after it is determined in the open inspection that the atmosphere release valve 24 is open. According to the above method, the liquid remaining in the cap 22 can be discharged together with the liquid remaining in the atmosphere release path 23.

[0098] (4) The control method of the liquid ejection device 11 includes performing a closed test after an open test. The closed test includes performing control to close the atmosphere release valve 24 while the cap 22 is in contact with the nozzle face 13, performing a decompression inside the cap 22 by the decompression unit 28, and determining that the atmosphere release valve 24 is closed when the measured pressure is equal to or less than the second threshold value. According to the above method, since the closed test is performed after the open test, the pressure inside the cap 22 can be measured in a state where the influence of the liquid remaining in the atmosphere release path 23 is reduced. This allows the atmosphere release valve 24 to be properly tested.

[0099] (5) The control method of the liquid ejection device 11 includes executing a closed test immediately after the open test. The control method of the liquid ejection device 11 includes continuing the decompression by the decompression unit 28 that was started in the open test throughout the closed test. With the above configuration, the time required for the closed test can be shortened compared to the case where the decompression unit 28 is stopped between the open test and the closed test.

[0100] <Example of change> This embodiment can be modified as follows: The above embodiment and the following modified examples can be combined with each other to the extent that there is no technical contradiction.

[0101] The open inspection, the close inspection, the wiper inspection, the discharge process, and the factor determination inspection may be executed by a control device such as a computer connected to the liquid ejection device 11. The liquid ejected by the ejection unit 12 is not limited to ink, and may be, for example, a liquid in which particles of a functional material are dispersed or mixed in a liquid. For example, the ejection unit 12 may eject a liquid containing, in a dispersed or dissolved form, a material such as an electrode material or a pixel material used in the manufacture of liquid crystal displays, electroluminescence displays, and surface-emitting displays.

[0102] <Technical philosophy> The technical ideas and effects obtained from the above-mentioned embodiment and modified examples will be described below.

[0103] (A) A method for controlling a liquid ejection device includes an ejection unit having a nozzle surface on which a nozzle is opened and ejecting liquid from the nozzle, a cap that covers the nozzle by contacting the nozzle surface, a pressure reducing unit that reduces the pressure inside the cap, a measurement unit that measures the pressure inside the cap, an air release path that connects the inside of the cap to the atmosphere, and an air release valve that opens and closes the air release path, and includes performing an open inspection including starting the pressure reduction by the pressure reducing unit after performing control to open the air release valve with the cap in contact with the nozzle surface, and determining that the air release valve is open if the pressure measured by the measurement unit after a predetermined waiting time has elapsed since the pressure reduction by the pressure reducing unit was started. When the pressure reducing unit reduces the pressure inside the cap with the cap in contact with the nozzle surface and the air release valve open, air flows into the cap through the air release path. At this time, if liquid remains in the air release path, air is less likely to flow into the cap. In other words, if liquid remains in the air release path, the negative pressure inside the cap increases due to the pressure reduction by the pressure reducing unit. Therefore, even though the atmospheric release valve is open, the negative pressure inside the cap is large, so that it may be determined that the atmospheric release valve is closed. According to the above method, the decompression by the decompression unit continues for the waiting time, so that the liquid remaining in the atmospheric release path is sucked. Therefore, the negative pressure inside the cap decreases as the waiting time passes after the decompression by the decompression unit starts. In other words, the pressure inside the cap can be measured in a state where the influence of the liquid remaining in the atmospheric release path is reduced as the waiting time passes after the decompression by the decompression unit starts. This allows the atmospheric release valve to be properly inspected.

[0104] (B) The control method for the liquid ejection device may include continuing the decompression by the decompression unit even after it is determined in the open test that the atmosphere release valve is open. According to the method, liquid remaining in the atmosphere release path is easily discharged.

[0105] (C) The method for controlling the liquid ejection device may include continuing the decompression by the decompression unit for a predetermined duration after determining that the atmosphere release valve is open in the open test. According to the method, the liquid remaining in the cap can be discharged together with the liquid remaining in the atmosphere release path.

[0106] (D) The control method of the liquid ejection device may include performing a closing test after the opening test, the threshold being a first threshold, and the closing test may include performing control to close the atmosphere release valve while the cap is in contact with the nozzle face, performing decompression by the decompression unit, and determining that the atmosphere release valve is closed when the pressure measured by the measurement unit is equal to or less than a second threshold. According to the above method, since the closing test is performed after the opening test, the pressure inside the cap can be measured in a state where the influence of liquid remaining in the atmosphere release path is reduced. This allows the atmosphere release valve to be properly inspected.

[0107] (E) The method of controlling the liquid ejection device may include performing the closed test immediately after the open test, and continuing the decompression by the decompression unit that was started in the open test throughout the closed test. With the above configuration, the time required for the closed test can be shortened compared to a case in which the decompression unit is stopped between the open test and the closed test.

[0108] (F) A liquid ejection device includes a nozzle surface on which a nozzle is opened and an ejection section that ejects liquid from the nozzle, a cap that covers the nozzle by contacting the nozzle surface, a pressure reducing section that reduces the pressure inside the cap, a measurement section that measures the pressure inside the cap, an atmosphere release path that connects the inside of the cap to the atmosphere, an atmosphere release valve that opens and closes the atmosphere release path, and a control section, wherein the control section executes control to open the atmosphere release valve while the cap is in contact with the nozzle surface, and then starts depressurization by the depressurization section, and executes an open inspection to determine that the atmosphere release valve is open if the pressure measured by the measurement section after a predetermined waiting time has elapsed since the start of depressurization by the depressurization section is equal to or greater than a threshold value. With the above configuration, the same effect as the above-mentioned method can be obtained.

[0109] (G) In the liquid ejection device, the control unit may continue decompression by the decompression unit even after determining that the atmosphere release valve is open in the open inspection. According to the above configuration, the same effect as the above-mentioned method can be obtained.

[0110] (H) In the above liquid ejection device, the threshold value may be a first threshold value, and the control unit may execute a control to close the atmosphere release valve with the cap in contact with the nozzle face after the open test, execute a depressurization by the depressurization unit, and execute a closed test to determine that the atmosphere release valve is closed if the pressure measured by the measurement unit is equal to or less than a second threshold value. With the above configuration, the same effect as the above-mentioned method can be obtained. [Explanation of symbols]

[0111] 11...liquid ejection device, 12...ejection section, 13...nozzle surface, 14...nozzle, 15...liquid container, 16...connection flow path, 17...subtank, 18...pressurization section, 21...maintenance section, 22...cap, 23...atmospheric release path, 24...atmospheric release valve, 25...wiper, 26...blade, 27...holder, 28...pressurization section, 29...cap pressure reduction path, 30...wiper pressure reduction path, 31...buffer, 32...cap opening / closing valve, 33...wiper opening / closing valve, 34...pressurization pump, 35...pressurization flow path, 36...pressurization flow path, 37...pressurization flow path valve, 38...pressurization flow path valve, 39...pressurization release path, 40...pressurization release path, 41...pressurization release valve, 42...pressurization release valve, 43...discharge flow path, 44...discharge valve, 45...maintenance box, 46...moisture permeable membrane, 47...absorbent, 48...measurement section, 50...control section.

Claims

1. a discharge section having a nozzle surface on which nozzles are opened and configured to discharge liquid from the nozzles; a cap for covering the nozzle by contacting the nozzle face; A pressure reducing unit that reduces the pressure inside the cap; A measurement unit for measuring a pressure inside the cap; an atmosphere opening passage that connects the inside of the cap to the atmosphere; an atmosphere release valve that opens and closes the atmosphere release path, executing control to open the atmosphere release valve in a state where the cap is in contact with the nozzle face, and then starting a pressure reduction by the pressure reduction unit; A control method for a liquid ejection device, comprising: performing an open test, the control method including: determining that the atmospheric release valve is open if the pressure measured by the measurement unit after a predetermined waiting time has elapsed since the start of pressure reduction by the pressure reduction unit is equal to or greater than a threshold value.

2. 2. The method for controlling a liquid ejection device according to claim 1, further comprising continuing the decompression by the decompression unit even after it is determined that the atmosphere release valve is open in the open inspection.

3. The method for controlling a liquid ejection device according to claim 2 , further comprising: continuing the decompression by the decompression unit for a predetermined duration after determining that the atmosphere release valve is open in the open inspection.

4. performing a close test after the open test; the threshold is a first threshold, The closure test is executing control to close the atmosphere release valve while keeping the cap in contact with the nozzle face, and executing pressure reduction by the pressure reduction unit; The method for controlling a liquid ejection device according to claim 3 , further comprising: determining that the atmosphere release valve is closed when the pressure measured by the measurement unit is equal to or less than a second threshold value.

5. performing the close test subsequent to the open test; The method for controlling a liquid ejection device according to claim 4 , further comprising: continuing the decompression by the decompression unit, which has been started in the open test, throughout the closed test.

6. a discharge section having a nozzle surface on which nozzles are opened and configured to discharge liquid from the nozzles; a cap for covering the nozzle by contacting the nozzle face; A pressure reducing unit that reduces the pressure inside the cap; A measurement unit for measuring a pressure inside the cap; an atmosphere opening passage that connects the inside of the cap to the atmosphere; an atmosphere release valve that opens and closes the atmosphere release path; A control unit, The control unit executes control to open the atmospheric release valve while the cap is in contact with the nozzle surface, then starts decompression by the pressure reduction unit, and performs an open test to determine that the atmospheric release valve is open if the measured pressure by the measurement unit after a predetermined waiting time has elapsed since the start of decompression by the pressure reduction unit is equal to or greater than a threshold value.

7. The liquid ejection device according to claim 6 , wherein the control unit continues decompression by the decompression unit even after determining that the atmosphere release valve is open in the open inspection.

8. the threshold is a first threshold, The liquid ejection device described in claim 7, characterized in that after the open test, the control unit executes control to close the atmospheric release valve while the cap is in contact with the nozzle face, and also executes a decompression test using the decompression unit, and determines that the atmospheric release valve is closed if the pressure measured by the measurement unit is equal to or lower than a second threshold value.

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