Liquid discharge device and control method for liquid discharge device

Abstract

To provide a liquid discharge device capable of reducing the risk of air entering a discharge part from a nozzle.SOLUTION: A liquid discharge device includes: a discharge part that discharges liquid from a nozzle; a storage part that is connected to the discharge part; a pressure variable unit that is connected to the storage part; and a control part that controls the pressure variable unit. The storage part includes a membrane member that divides the interior of the storage part into an air chamber and a liquid chamber. The liquid chamber communicates with the discharge part, and the air chamber communicates with the pressure variable unit. The pressure variable unit includes a vacuum pump for depressurizing the air chamber, and a motor for driving the vacuum pump. The control part gradually increases the applied voltage until the applied voltage of the motor reaches a target voltage.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] Patent Document 1 describes a liquid ejection device including an ejection unit that ejects liquid from a nozzle and a storage unit connected to the ejection unit. The storage unit has a film member that divides the inside of the storage unit into an air chamber and a liquid chamber. The liquid ejection device has a decompression pump that decompresses the air chamber. When the decompression pump decompresses the air chamber, liquid flows from the ejection unit into the liquid chamber. When the decompression pump stops, the liquid chamber is pressurized by air flowing into the air chamber. Thereby, the liquid ejection device discharges liquid from the nozzle or circulates the liquid.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such a liquid ejection device, when the decompression pump rapidly decompresses the air chamber, air may flow into the ejection unit from the nozzle.

Means for Solving the Problems

[0005] The liquid ejection device for solving the above problems includes a discharge unit that discharges liquid from a nozzle, a storage unit connected to the discharge unit, a pressure variable unit connected to the storage unit, and a control unit that controls the pressure variable unit. The storage unit has a membrane member that divides the inside of the storage unit into an air chamber and a liquid chamber. The liquid chamber communicates with the discharge unit, and the air chamber communicates with the pressure variable unit. The pressure variable unit has a decompression pump that decompresses the air chamber and a motor that drives the decompression pump. The control unit gradually increases the applied voltage until the applied voltage of the motor reaches the target voltage.

[0006] The control method of the liquid ejection device for solving the above problems includes a discharge unit that discharges liquid from a nozzle, a supply flow path through which the liquid supplied to the discharge unit flows, and a flow unit connected to the supply flow path and the discharge unit and controlling the flow of the liquid supplied to the discharge unit. The control method further includes a pressure variable unit connected to the flow unit and a control unit that controls the pressure variable unit. The flow unit has a membrane member that divides the flow space inside the flow unit into an air chamber and a liquid chamber, and a regulating valve located upstream of the liquid chamber. The liquid chamber communicates with the discharge unit, and the air chamber communicates with the pressure variable unit. The pressure variable unit has a decompression pump that decompresses the air chamber and a motor that drives the decompression pump. The regulating valve is configured to open when the pressure in the liquid chamber becomes equal to or lower than a predetermined pressure. The control method gradually increases the applied voltage until the applied voltage applied to the motor reaches the target voltage.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the liquid ejection device will be described 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 ejection device> As shown in FIG. 1, the liquid ejection device 11 includes a liquid ejection unit 12. The liquid ejection unit 12 is configured to eject a liquid. The liquid ejection unit 12 prints an image on the medium M1 by ejecting the liquid onto the medium M1.

[0010] The liquid is supplied to the liquid ejection unit 12 from a liquid container 13. The liquid container 13 stores the liquid. The liquid container 13 is, for example, an ink cartridge, an ink tank, or the like. The liquid container 13 is attached to the liquid ejection device 11. The liquid ejection device 11 is configured to be able to attach the liquid container 13.

[0011] The liquid ejection unit 12 has a discharge unit 14. The discharge unit 14 has a nozzle surface 15. The nozzle surface 15 is a surface facing the medium M1. One or more nozzles 16 are open on the nozzle surface 15. The discharge unit 14 discharges the liquid from the nozzles 16.

[0012] The liquid ejection device 11 includes one or more storage units 17 connected to the discharge unit 14. In one example, the liquid ejection device 11 includes a plurality of storage units 17. The storage unit 17 is configured to store the liquid. The storage unit 17 is located between the liquid container 13 and the discharge unit 14. The storage unit 17 stores the liquid between the liquid container 13 and the discharge unit 14. The storage unit 17 is, for example, an on-off valve 23, a pressurizing unit 24, and a flow path pump 44. The on-off valve 23, the pressurizing unit 24, and the flow path pump 44 will be described later.

[0013] Based on FIG. 2, the common configuration of the accommodating portion 17 will be described. As shown in FIG. 2, the accommodating portion 17 has a membrane member 18. The membrane member 18 is a flexible member. The membrane member 18 is deformable. The membrane member 18 divides the inside of the accommodating portion 17 into a liquid chamber C1 and an air chamber C2. The liquid chamber C1 is a space in which liquid is accommodated. The air chamber C2 is a space in which air is accommodated. The membrane member 18 partitions the liquid chamber C1 and the air chamber C2. The membrane member 18 constitutes the wall surface of the liquid chamber C1 and the wall surface of the air chamber C2. The membrane member 18 deforms according to the pressure in the liquid chamber C1 and the pressure in the air chamber C2. When the membrane member 18 deforms, the volume of the liquid chamber C1 and the volume of the air chamber C2 change.

[0014] A plurality of openings are formed in the accommodating portion 17. Through the plurality of openings, liquid and air are supplied into the accommodating portion 17, or liquid and air are discharged from the accommodating portion 17. In one example, an inlet H1, an outlet H2, and an air port H3 open in the accommodating portion 17. The inlet H1 communicates with the liquid chamber C1. Through the inlet H1, liquid flows into the liquid chamber C1. The outlet H2 communicates with the liquid chamber C1. Through the outlet H2, liquid flows out of the liquid chamber C1. The air port H3 communicates with the air chamber C2. Through the air port H3, air is supplied to the air chamber C2 or air is discharged from the air chamber C2. That is, through the air port H3, the air chamber C2 is pressurized or the air chamber C2 is depressurized. When the air chamber C2 is pressurized, the membrane member 18 deforms so as to reduce the volume of the liquid chamber C1. As a result, liquid flows out of the liquid chamber C1 through the outlet H2. When the air chamber C2 is depressurized, the membrane member 18 deforms so as to increase the volume of the liquid chamber C1. As a result, liquid flows into the liquid chamber C1 through the inlet H1.

[0015] As shown in FIG. 1, the liquid ejection unit 12 has a flow portion 21. In the flow portion 21, the liquid supplied to the ejection portion 14 flows. The flow portion 21 is connected to the ejection portion 14. The flow portion 21 is located between the liquid container 13 and the ejection portion 14.

[0016] The fluid section 21 may have a regulating valve 22. The regulating valve 22 is configured to open and close. The regulating valve 22 is normally closed. When the regulating valve 22 opens, liquid flows into the fluid section 21.

[0017] The regulating valve 22 is configured to adjust the pressure in the discharge section 14. In one example, the regulating valve 22 is configured to adjust the pressure in the fluid section 21. The regulating valve 22 adjusts the pressure in the fluid section 21 by opening and closing based on the pressure in the fluid section 21. The regulating valve 22 adjusts the pressure in the discharge section 14 by adjusting the pressure in the fluid section 21.

[0018] The regulating valve 22 is configured to open and close according to the differential pressure between the pressure in the discharge section 14 and the atmospheric pressure. In one example, the regulating valve 22 opens and closes according to the differential pressure between the pressure in the fluid section 21 and the atmospheric pressure. Specifically, the regulating valve 22 opens when the pressure downstream of itself is below a predetermined pressure. That is, the regulating valve 22 opens when the pressure in the fluid section 21 is below a predetermined pressure. The regulating valve 22 closes when the pressure in the fluid section 21 is greater than the predetermined pressure.

[0019] The regulating valve 22 maintains the inside of the fluid section 21 at a predetermined pressure by opening and closing. The regulating valve 22 maintains the inside of the discharge section 14 at a predetermined pressure by maintaining the inside of the fluid section 21 at a predetermined pressure. The operating pressure at which the regulating valve 22 opens is a predetermined negative pressure. Therefore, the inside of the discharge section 14 is maintained at a predetermined negative pressure by the regulating valve 22. When the inside of the discharge section 14 is maintained at a predetermined negative pressure, a meniscus is formed at the nozzle 16. When a meniscus is formed at the nozzle 16, the discharge section 14 can discharge the liquid well.

[0020] The operating pressure of the regulating valve 22 is greater than the meniscus withstand pressure. Therefore, the inside of the discharge section 14 is maintained at a negative pressure to such an extent that the meniscus is maintained by the regulating valve 22. If the negative pressure inside the discharge section 14 exceeds the meniscus withstand pressure, that is, if the pressure inside the discharge section 14 is below the meniscus withstand pressure, the meniscus may be destroyed. If the meniscus is destroyed, air may flow into the discharge section 14 through the nozzle 16.

[0021] The flow unit 21 has one or more accommodating parts 17. The flow unit 21 has, for example, an on-off valve 23 and a pressurizing part 24. The on-off valve 23 and the pressurizing part 24 are an example of the accommodating part 17. The on-off valve 23 and the pressurizing part 24 are located downstream of the regulating valve 22. In the flow unit 21, the liquid is supplied to the discharge part 14 by passing through the regulating valve 22, the on-off valve 23, and the pressurizing part 24 in this order.

[0022] The on-off valve 23 is connected to the regulating valve 22. The on-off valve 23 is connected to the pressurizing part 24. The on-off valve 23 is connected to the discharge part 14 through the pressurizing part 24. The on-off valve 23 is configured to open and close. Different from the regulating valve 22, the on-off valve 23 is configured to open and close arbitrarily. The on-off valve 23 closes by changing the pressure in the air chamber C2 of the on-off valve 23. The on-off valve 23 closes when cleaning the discharge part 14. Specifically, the on-off valve 23 closes when the pressurizing part 24 cleans the discharge part 14. The on-off valve 23 is normally open.

[0023] The pressurizing part 24 is connected to the on-off valve 23. The pressurizing part 24 is connected to the discharge part 14. The pressurizing part 24 is configured to pressurize the inside of the discharge part 14. The pressurizing part 24 pressurizes the inside of the discharge part 14 by changing the pressure in the air chamber C2 of the pressurizing part 24. The pressurizing part 24 cleans the discharge part 14 by pressurizing the inside of the discharge part 14. Specifically, the pressurizing part 24 discharges the liquid from the nozzle 16 by pressurizing the inside of the discharge part 14. Thereby, the thickened liquid, foreign matters, etc. are discharged from the inside of the discharge part 14. When the pressurizing part 24 pressurizes the inside of the discharge part 14, closing the on-off valve 23 reduces the risk of liquid backflow from the pressurizing part 24. By closing the on-off valve 23, that is, choking, the pressurizing part 24 can effectively pressurize the inside of the discharge part 14.

[0024] As shown in FIG. 3, the flow section 21 has a flow member 25. The flow member 25 also defines a space for accommodating a liquid. The flow member 25 is a member that defines a space for accommodating air. In one example, the flow member 25 constitutes an on-off valve 23 and a pressurizing section 24. The flow member 25 may constitute a regulating valve 22.

[0025] The flow member 25 defines a choke space C3. The choke space C3 is a space within the on-off valve 23. A choke inlet H4 and a choke outlet H5 open in the flow member 25. The choke inlet H4 is an example of the inlet H1. The choke outlet H5 is an example of the outlet H2. A choke air port H6 opens in the flow member 25. The choke air port H6 is an example of the air port H3.

[0026] The flow member 25 defines a pressurizing space C4. The pressurizing space C4 is a space within the pressurizing section 24. A pressurizing inlet H7 and a pressurizing outlet H8 open in the flow member 25. The pressurizing inlet H7 is an example of the inlet H1. The pressurizing outlet H8 is an example of the outlet H2. A pressurizing air port H9 opens in the flow member 25. The pressurizing air port H9 is an example of the air port H3.

[0027] The flow section 21 has a choke diaphragm 26. The choke diaphragm 26 is attached to the flow member 25. The choke diaphragm 26 is an example of the membrane member 18. The choke diaphragm 26 constitutes the on-off valve 23. The choke diaphragm 26 divides the choke space C3 into a choke liquid chamber C5 and a choke air chamber C6. The choke liquid chamber C5 is an example of the liquid chamber C1. The choke liquid chamber C5 communicates with the choke inlet H4 and the choke outlet H5. The choke air chamber C6 is an example of the air chamber C2. The choke air chamber C6 communicates with the choke air port H6.

[0028] The choke film 26 has a valve portion 27 and an operating portion 28. The valve portion 27 is a portion that closes the choke inlet H4 or the choke outlet H5. In one example, the valve portion 27 closes the choke outlet H5. The valve portion 27 closes the choke outlet H5 when pressed against a lever 29 described later. The operating portion 28 is a portion that operates the lever 29.

[0029] The operating portion 28 is configured to be more easily deformed than the valve portion 27. In one example, the operating portion 28 is configured to have less elasticity than the valve portion 27. For example, the thickness of the operating portion 28 may be smaller than the thickness of the valve portion 27. The area of the operating portion 28 facing the choke air chamber C6 may be larger than the area of the valve portion 27 facing the choke air chamber C6.

[0030] When the choke air chamber C6 is depressurized, the valve portion 27 and the operating portion 28 deform so as to reduce the volume of the choke air chamber C6. At this time, the operating portion 28 is more easily deformed than the valve portion 27.

[0031] The fluid portion 21 has a lever 29. The lever 29 constitutes an on-off valve 23. The lever 29 is attached to the fluid member 25. The lever 29 is located in the choke space C3. Specifically, the lever 29 is located in the choke air chamber C6. The lever 29 has, for example, a shaft portion 30. The shaft portion 30 is attached to the fluid member 25. The lever 29 is displaced about the shaft portion 30. The lever 29 is displaced in the choke air chamber C6.

[0032] The lever 29 has a first portion 31 and a second portion 32. The first portion 31 is a portion including one end of the lever 29. The first portion 31 is positioned to contact the valve portion 27. The second portion 32 is a portion including the other end of the lever 29. The second portion 32 is positioned to contact the operating portion 28.

[0033] When the choke air chamber C6 is depressurized, the valve portion 27 deforms to push up the first portion 31. The operating portion 28 deforms to push up the second portion 32. Since the operating portion 28 is more deformable than the valve portion 27, the force with which the operating portion 28 pushes up the lever 29 is greater than the force with which the valve portion 27 pushes up the lever 29. Therefore, the lever 29 is displaced such that the first portion 31 pushes down the valve portion 27. That is, the lever 29 presses the valve portion 27 against the choke outlet H5. As a result, the choke outlet H5 is blocked.

[0034] The fluid portion 21 has a pressure membrane 33. The pressure membrane 33 is attached to the fluid member 25. The pressure membrane 33 is an example of the membrane member 18. The pressure membrane 33 constitutes the pressurizing portion 24. The pressure membrane 33 divides the pressurizing space C4 into a pressurized liquid chamber C7 and a pressurized air chamber C8. The pressurized liquid chamber C7 is an example of the liquid chamber C1. The pressurized liquid chamber C7 communicates with a pressurized inlet H7 and a pressurized outlet H8. The pressurized air chamber C8 is an example of the air chamber C2. The pressurized air chamber C8 communicates with a pressurized air port H9.

[0035] The fluid portion 21 may have a pressurizing member 34. The pressurizing member 34 is configured to press against the pressure membrane 33. Specifically, the pressurizing member 34 presses against the pressure membrane 33 such that the volume of the pressurized liquid chamber C7 decreases. The pressurizing member 34 is located in the pressurized air chamber C8. The pressurizing member 34 is attached to the fluid member 25 and the pressure membrane 33.

[0036] When the pressurized air chamber C8 is depressurized, the pressure membrane 33 is displaced such that the volume of the pressurized air chamber C8 decreases. At this time, the pressure membrane 33 is displaced such that the volume of the pressurized liquid chamber C7 increases. As a result, liquid flows into the pressurized liquid chamber C7. Specifically, liquid flows into the pressurized liquid chamber C7 from the discharge portion 14, the regulating valve 22, the on-off valve 23, etc. When the pressurized air chamber C8 is pressurized or opened to the atmosphere, the pressure membrane 33 deforms such that the volume of the pressurized liquid chamber C7 decreases. At this time, the liquid in the pressurized liquid chamber C7 is pressurized. As a result, liquid is discharged from the nozzle 16.

[0037] As shown in FIG. 1, the liquid ejection unit 12 may have a moving body 36. The moving body 36 mounts the ejection part 14. The moving body 36 mounts the flow part 21. The moving body 36 is movable. The moving body 36 moves in the scanning direction with respect to the medium M1. The liquid ejection unit 12 is a serial head capable of ejecting liquid over the entire width of the medium M1. The liquid ejection unit 12 may also be a line head capable of ejecting liquid all at once over the entire width of the medium M1.

[0038] The liquid ejection device 11 includes a liquid supply unit 41. The liquid supply unit 41 is connected to the liquid container 13 and the liquid ejection unit 12. The liquid supply unit 41 is configured to supply liquid to the liquid ejection unit 12.

[0039] The liquid supply unit 41 has a supply channel 42. The supply channel 42 is a channel through which liquid flows. Specifically, the supply channel 42 is a channel through which the liquid supplied to the ejection part 14 flows. Liquid is supplied to the liquid ejection unit 12 through the supply channel 42. The supply channel 42 is connected to the liquid container 13 and the liquid ejection unit 12. In one example, the supply channel 42 is connected to the liquid container 13 and the flow part 21.

[0040] The liquid supply unit 41 may have a supply valve 43. In one example, the liquid supply unit 41 has a supply valve 43. The supply valve 43 is located in the supply channel 42. Specifically, the supply valve 43 is located between the liquid container 13 and a channel pump 44 described later. The supply valve 43 is a valve that controls the flow of liquid in the supply channel 42. The supply valve 43 is, for example, a one-way valve. The supply valve 43 allows liquid to flow from the liquid container 13 toward the liquid ejection unit 12 in the supply channel 42. The supply valve 43 restricts liquid from flowing from the liquid ejection unit 12 toward the liquid container 13 in the supply channel 42. The supply valve 43 may be an electromagnetic valve that can be arbitrarily opened and closed.

[0041] The liquid supply unit 41 has a flow path pump 44. The flow path pump 44 is an example of the housing portion 17. The flow path pump 44 is a so-called diaphragm pump. The flow path pump 44 is located in the supply flow path 42. The flow path pump 44 is located between the liquid container 13 and the liquid discharge unit 12. Specifically, the flow path pump 44 is located between the supply valve 43 and the liquid discharge unit 12. The flow path pump 44 is configured to supply liquid from the liquid container 13 toward the liquid discharge unit 12. The flow path pump 44 supplies liquid from the liquid container 13 toward the liquid discharge unit 12 by changing the air chamber C2 of the flow path pump 44.

[0042] The flow path pump 44 has a diaphragm 45 which is an example of a membrane member. The diaphragm 45 divides the inside of the flow path pump 44 into a flow path liquid chamber C11 and a flow path air chamber C12. The flow path liquid chamber C11 is an example of the liquid chamber C1. The flow path air chamber C12 is an example of the air chamber C2.

[0043] The flow path pump 44 has a pressing member 46. The pressing member 46 is configured to press the diaphragm 45. Specifically, the pressing member 46 presses the diaphragm 45 so that the volume of the flow path liquid chamber C11 becomes smaller. That is, the pressing member 46 presses the diaphragm 45 so as to pressurize the flow path liquid chamber C11. The pressing member 46 is located in the flow path air chamber C12.

[0044] When the flow path air chamber C12 is depressurized, the diaphragm 45 deforms so that the volume of the flow path liquid chamber C11 becomes larger. Thereby, liquid flows into the flow path liquid chamber C11 from the liquid container 13. When the flow path air chamber C12 is pressurized or opened to the atmosphere, the diaphragm 45 deforms so that the volume of the flow path liquid chamber C11 becomes smaller by the pressing member 46. Thereby, liquid flows out from the flow path liquid chamber C11 toward the flow portion 21.

[0045] The liquid supply unit 41 has a pressure variable unit 47. The pressure variable unit 47 is connected to the housing part 17. In one example, the pressure variable unit 47 is connected to each of the on-off valve 23, the pressurizing part 24, and the flow path pump 44.

[0046] The pressure variable unit 47 is configured to change the pressure of the housing part 17. In one example, the pressure variable unit 47 is configured to change the pressure of any one of the plurality of housing parts 17. The pressure variable unit 47 changes the pressure of the air chamber C2. In one example, the pressure variable unit 47 decompresses the air chamber C2.

[0047] The pressure variable unit 47 has a vacuum pump 48. The vacuum pump 48 is a pump that generates a negative pressure. The vacuum pump 48 is connected to the housing part 17. The vacuum pump 48 decompresses the air chamber C2.

[0048] The pressure variable unit 47 has a motor 49. The motor 49 is connected to the vacuum pump 48. The motor 49 drives the vacuum pump 48. That is, the vacuum pump 48 is driven by the power of the motor 49. The motor 49 operates, for example, by PWM control.

[0049] The liquid supply unit 41 has an air flow path 50. The air flow path 50 is connected to the pressure variable unit 47 and the housing part 17. In one example, the air flow path 50 is connected to the vacuum pump 48 and the on-off valve 23. The air flow path 50 is connected to the vacuum pump 48 and the pressurizing part 24. The air flow path 50 is connected to the vacuum pump 48 and the flow path pump 44. Through the air flow path 50, the air chamber C2 is decompressed by the vacuum pump 48.

[0050] The liquid supply unit 41 has one or more air valves. In one example, the liquid supply unit 41 has a first air valve 51, a second air valve 52, and a third air valve 53. The air valves are located in the air flow path 50. The air valves are configured to open and close. The air valves are, for example, solenoid valves. The first air valve 51 is located between the vacuum pump 48 and the on-off valve 23. When the first air valve 51 opens, the on-off valve 23 can be depressurized by the vacuum pump 48. The second air valve 52 is located between the vacuum pump 48 and the pressurizing unit 24. When the second air valve 52 opens, the pressurizing unit 24 can be depressurized by the vacuum pump 48. The third air valve 53 is located between the vacuum pump 48 and the flow path pump 44. When the third air valve 53 opens, the flow path pump 44 can be depressurized by the vacuum pump 48.

[0051] The liquid supply unit 41 has an atmosphere release valve 54. The atmosphere release valve 54 is connected to the air flow path 50. The atmosphere release valve 54 is configured to open and close. The atmosphere release valve 54 is, for example, a solenoid valve. When the atmosphere release valve 54 opens, the air flow path 50 is opened to the atmosphere. Through the air flow path 50, the housing portion 17 is opened to the atmosphere. Specifically, when the atmosphere release valve 54 and the first air valve 51 open, the on-off valve 23 is opened to the atmosphere. When the atmosphere release valve 54 and the second air valve 52 open, the pressurizing unit 24 is opened to the atmosphere. When the atmosphere release valve 54 and the third air valve 53 open, the flow path pump 44 is opened to the atmosphere.

[0052] The liquid ejection device 11 includes a power supply circuit 56. The power supply circuit 56 is connected to the liquid supply unit 41. The power supply circuit 56 is connected to the pressure variable unit 47. The power supply circuit 56 is connected to the motor 49. The power supply circuit 56 applies a voltage to the motor 49. The power supply circuit 56 applies an arbitrary voltage to the motor 49. When the power supply circuit 56 applies a voltage to the motor 49, the motor 49 starts.

[0053] The liquid ejection device 11 includes a control unit 57. The control unit 57 controls the liquid supply unit 41. The control unit 57 controls the pressure variable unit 47. The control unit 57 controls the power supply circuit 56. By controlling the power supply circuit 56, the control unit 57 controls the applied voltage of the motor 49. The control unit 57 controls the applied voltage by PWM control. By controlling the applied voltage, the control unit 57 controls the vacuum pump 48. Thereby, the control unit 57 controls the negative pressure generated by the vacuum pump 48.

[0054] The control unit 57 controls the air valve. By controlling the air valve, the control unit 57 controls the operation of the storage unit 17. The control unit 57 controls the atmosphere release valve 54. By controlling the atmosphere release valve 54, the control unit 57 controls the operation of the storage unit 17. By controlling the air valve and the atmosphere release valve 54, the control unit 57 decompresses an arbitrary storage unit 17 or opens it to the atmosphere. Thereby, the control unit 57 controls the flow of the liquid.

[0055] The control unit 57 executes cleaning by controlling the operations of the on-off valve 23 and the pressurizing unit 24. In one example, first, the control unit 57 opens the second air valve 52. Next, the control unit 57 starts the motor 49. Thereby, the pressurized air chamber C8 is decompressed by the vacuum pump 48. As a result, the liquid flows into the pressurized liquid chamber C7. Next, the control unit 57 closes the second air valve 52. Thereby, the pressurized air chamber C8 is maintained at a negative pressure. Next, the control unit 57 opens the first air valve 51. Thereby, the choke air chamber C6 is decompressed by the vacuum pump 48. As a result, the on-off valve 23 closes. Next, the control unit 57 opens the second air valve 52 and the atmosphere release valve 54. Thereby, the pressurized air chamber C8 is opened to the atmosphere. As a result, the liquid is discharged from the nozzle 16.

[0056] The control unit 57 supplies liquid to the liquid discharge unit 12 by controlling the flow path pump 44. In one example, first, the control unit 57 opens the third air valve 53. Next, the control unit 57 starts the motor 49. As a result, the pressure in the flow path air chamber C12 is reduced by the vacuum pump 48. Consequently, liquid flows from the liquid container 13 into the flow path liquid chamber C11. Next, the control unit 57 opens the atmosphere release valve 54. As a result, the flow path air chamber C12 is opened to the atmosphere. Consequently, the diaphragm 45 pressurizes the liquid in the flow path liquid chamber C11. Therefore, liquid flows out from the flow path liquid chamber C11 toward the liquid discharge unit 12.

[0057] The control unit 57 may control not only the liquid supply unit 41 but also the liquid discharge unit 12. The control unit 57 may comprehensively control the liquid discharge device 11. The control unit 57 may be composed of one or more processors that execute various processes according to a computer program. The control unit 57 may be composed of one or more dedicated hardware circuits such as an ASIC that execute at least some of the various processes. The control unit 57 may be composed of a circuit including 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 codes or instructions configured to cause the CPU to execute processes. The memory, that is, the computer-readable medium, includes any readable medium accessible by a general-purpose or dedicated computer.

[0058] <Control of Applied Voltage> Next, the control of the applied voltage by the control unit 57 will be described. When the control unit 57 chokes with the on-off valve 23, the control unit 57 drives the motor 49 at the target voltage. When the control unit 57 cleans the discharge unit 14 with the pressurizing unit 24, the control unit 57 drives the motor 49 at the target voltage. When the control unit 57 supplies liquid to the discharge unit 14 with the flow path pump 44, the control unit 57 drives the motor 49 at the target voltage. By driving the motor 49 at the target voltage, the accommodation unit 17 can be sufficiently depressurized.

[0059] When the pressure in the storage section 17 is reduced, the negative pressure in the storage section 17 may act on the discharge section 14. Therefore, if the pressure in the storage section 17 is rapidly reduced, the meniscus in the nozzle 16 may be damaged. In one example, when the pressure in the pressurizing section 24 is reduced, the negative pressure in the pressurizing section 24 acts on the discharge section 14 until the regulating valve 22 opens. If the pressure in the pressurizing section 24 is rapidly reduced, the meniscus in the nozzle 16 may be damaged. Therefore, the control unit 57 controls the applied voltage of the motor 49 to reduce the pressure in the storage section 17 so as not to damage the meniscus.

[0060] As shown in FIG. 4, the control unit 57 gradually increases the applied voltage of the motor 49 until the applied voltage reaches the target voltage. Specifically, the control unit 57 reaches the target voltage by increasing the applied voltage over a predetermined period of time. As a result, the pressure reducing pump 48 gradually reduces the pressure in the pressurizing section 24. Therefore, the risk of the meniscus being damaged is reduced. The control unit 57 controls the applied voltage of the motor 49 by PWM control, for example. The control unit 57 controls the applied voltage of the motor 49 by controlling the duty ratio with the power supply circuit 56.

[0061] As shown in FIG. 5, when the control unit 57 gradually increases the applied voltage, the pressurized air chamber C8 is gradually depressurized. The solid line graph in FIG. 5 shows the pressure change of the pressurized air chamber C8 when the applied voltage is gradually increased. The broken line graph in FIG. 5 shows the pressure change of the pressurized air chamber C8 when the applied voltage immediately reaches the target voltage.

[0062] As shown in FIG. 6, when the control unit 57 gradually increases the applied voltage, the pressurized liquid chamber C7 is depressurized so that the pressure in the pressurized liquid chamber C7 does not exceed the meniscus pressure resistance. The meniscus pressure resistance is, for example, -2.0 kPa. The operating pressure of the regulating valve 22 is, for example, -1.0 kPa. In the graph shown in FIG. 6, the pressure in the pressurized liquid chamber C7 drops below -1.0 kPa and then rises. This is because when the regulating valve 22 opens, liquid flows into the pressurized liquid chamber C7.

[0063] When the air chamber C2 is depressurized by the vacuum pump 48, the control unit 57 gradually increases the applied voltage until the applied voltage reaches the target voltage so that the pressure in the discharge unit 14 does not fall below the meniscus withstand voltage. In one example, when the pressure in the discharge unit 14 does not fall below -2.0 kPa when the pressurized air chamber C8 is depressurized by the vacuum pump 48, the control unit 57 gradually increases the applied voltage. The pressure in the discharge unit 14 is usually maintained at the operating pressure of the regulating valve 22. Therefore, the pressure in the discharge unit 14 is usually -1.0 kPa. That is, the control unit 57 gradually increases the applied voltage so that the negative pressure acting in the discharge unit 14 by the vacuum pump 48 does not exceed -1.0 kPa. The control unit 57 gradually increases the applied voltage so that the sum of the negative pressure and the operating pressure acting in the discharge unit 14 by the vacuum pump 48 does not exceed the meniscus withstand voltage.

[0064] As shown in FIG. 4, the control unit 57 controls to gradually increase the applied voltage from a voltage lower than the starting voltage of the motor 49. Specifically, the control unit 57 controls to gradually increase the applied voltage from a voltage lower than the starting voltage range. That is, the control unit 57 makes the starting voltage applied to the motor 49 lower than the starting voltage. The starting voltage is the voltage at which the motor 49 starts to rotate. The starting voltage range is the voltage range indicating the range of the starting voltage. In the motor 49, there is a variation in the starting voltage. The starting voltage is the applied voltage at the start of application. By increasing the applied voltage from a voltage lower than the starting voltage, the possibility that the motor 49 starts to rotate vigorously immediately after the start of application is reduced. That is, the possibility that the pressurizing unit 24 is rapidly depressurized by the motor 49 with a low starting voltage is reduced.

[0065] The control unit 57 increases the applied voltage at a constant slope until a predetermined time elapses after starting to apply the voltage to the motor 49. The predetermined time is the time until the applied voltage becomes greater than the starting voltage. Specifically, the predetermined time is the time required until the negative pressure by the vacuum pump 48 acts on the housing part 17. When the predetermined time elapses, the motor 49 starts regardless of the variation in the starting voltage. Immediately after the motor 49 starts, the negative pressure by the vacuum pump 48 may not be acting on the pressurized air chamber C8. Therefore, the predetermined time needs to be longer than the time until the applied voltage reaches the starting voltage. When the predetermined time elapses while the slope of the applied voltage is maintained constant, the vacuum pump 48 can gently depressurize the pressurized air chamber C8.

[0066] After the predetermined time has elapsed, the control unit 57 increases the slope of the applied voltage. As a result, the time required until the applied voltage reaches the target voltage is shortened. After increasing the slope of the applied voltage, the control unit 57 maintains the applied voltage at an intermediate voltage lower than the target voltage for a certain time. If the applied voltage rapidly rises to the target voltage after increasing the slope of the applied voltage, there is a risk that the negative pressure in the discharge part 14 exceeds the meniscus pressure resistance. By having the applied voltage wait at the intermediate voltage, the risk of the pressurizing part 24 being rapidly depressurized is reduced.

[0067] After maintaining the applied voltage at the intermediate voltage for a certain time, the control unit 57 increases the applied voltage at a constant slope. The control unit 57, for example, increases the applied voltage from the intermediate voltage toward the target voltage at the slope after the predetermined time has elapsed. As a result, the time required until the applied voltage reaches the target voltage is shortened. Due to the intermediate voltage, the applied voltage changes in a stepwise manner. The control unit 57 may change the applied voltage via a plurality of intermediate voltages.

[0068] <Actions and Effects of the Embodiment> Next, the actions and effects of the above embodiment will be described. (1) The control unit 57 gradually increases the applied voltage until the applied voltage of the motor 49 reaches the target voltage. According to the above configuration, since the air chamber C2 is gradually depressurized, the possibility that the liquid rapidly flows from the discharge unit 14 into the liquid chamber C1 is reduced. Therefore, the possibility that air flows into the discharge unit 14 from the nozzle 16 is reduced.

[0069] (2) The control unit 57 increases the applied voltage from a voltage lower than the starting voltage of the motor 49. Usually, there is a variation in the starting voltage of the motor 49. According to the above configuration, the possibility that the motor 49 starts immediately after the voltage application to the motor 49 is reduced. Therefore, even when there is a variation in the starting voltage of the motor 49, the possibility that the air chamber C2 is rapidly depressurized is reduced.

[0070] (3) The control unit 57 increases the applied voltage at a constant slope until a predetermined time elapses after starting to apply the voltage to the motor 49. According to the above configuration, even when there is a variation in the starting voltage of the motor 49, the possibility that the air chamber C2 is rapidly depressurized is reduced.

[0071] (4) After the predetermined time has elapsed, the control unit 57 increases the slope of the applied voltage. According to the above configuration, compared with the case where the slope of the applied voltage remains constant, the time until the applied voltage reaches the target voltage is shortened.

[0072] (5) After increasing the slope of the applied voltage, the control unit 57 maintains the applied voltage at a relay voltage lower than the target voltage for a certain time. When the slope of the applied voltage increases, there is a possibility that the air chamber C2 is rapidly depressurized. In this case, there is a possibility that air flows into the discharge unit 14 from the nozzle 16. In this regard, according to the above configuration, since the applied voltage is maintained at the relay voltage for a certain time, the possibility that the air chamber C2 is rapidly depressurized is reduced.

[0073] (6) The flow unit 21 has a housing unit 17. According to the above configuration, the flow of the liquid supplied to the discharge unit 14 can be controlled by the housing unit 17. (7) The operating pressure of the regulating valve 22 is greater than the meniscus withstand pressure. According to the above configuration, the regulating valve 22 opens before the pressure in the liquid chamber C1 falls below the meniscus withstand pressure. Therefore, the risk of air flowing into the discharge portion 14 from the nozzle 16 is reduced.

[0074] <Modified Example> The above embodiment can be implemented with the following modifications. The above embodiment and the following modified examples can be implemented in combination with each other within a technically non - conflicting range.

[0075] · In the liquid discharge device 11, at least a part of the regulating valve 22, the on - off valve 23, and the pressurizing portion 24 may be provided in the supply flow path 42. That is, one of the regulating valve 22, the on - off valve 23, and the pressurizing portion 24 may be provided in the supply flow path 42, or two of the regulating valve 22, the on - off valve 23, and the pressurizing portion 24 may be provided in the supply flow path 42, or all of the regulating valve 22, the on - off valve 23, and the pressurizing portion 24 may be provided in the supply flow path 42.

[0076] · In the liquid discharge device 11, not limited to the regulating valve 22, for example, the inside of the discharge portion 14 may be maintained at a negative pressure by a head difference. In this case, the flow portion 21 does not have the regulating valve 22. In this modified example, the pressure in the flow path pump 44 acts on the discharge portion 14. Therefore, when driving the flow path pump 44, the control unit 57 may gradually increase the applied voltage. According to this modified example, the risk of air flowing into the discharge portion 14 from the nozzle 16 is reduced. Also, the liquid in the discharge portion 14 can be returned to the supply flow path 42. Thereby, the liquid can be agitated.

[0077] · The liquid discharged from the discharge portion 14 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 discharge portion 14 may discharge a liquid containing a material such as an electrode material or a pixel material used in the manufacture of a liquid crystal display, an electroluminescence display, and a surface - emitting display in a dispersed or dissolved form.

[0078] <Technical Idea> The following describes the technical idea and its effects grasped from the above-described embodiments and modified examples.

[0079] (A) The liquid ejection device includes a discharge unit that discharges liquid from a nozzle, a storage unit connected to the discharge unit, a pressure variable unit connected to the storage unit, and a control unit that controls the pressure variable unit. The storage unit has a membrane member that divides the inside of the storage unit into an air chamber and a liquid chamber. The liquid chamber communicates with the discharge unit, and the air chamber communicates with the pressure variable unit. The pressure variable unit has a decompression pump that decompresses the air chamber and a motor that drives the decompression pump. The control unit gradually increases the applied voltage until the applied voltage of the motor reaches the target voltage. According to the above configuration, since the air chamber is gradually decompressed, the possibility that the liquid rapidly flows from the discharge unit into the liquid chamber is reduced. Therefore, the possibility that air flows into the discharge unit from the nozzle is reduced.

[0080] (B) In the liquid ejection device, the control unit may increase the applied voltage from a voltage lower than the starting voltage of the motor. Usually, there is variation in the starting voltage of the motor. According to the above configuration, the possibility that the motor starts immediately after the voltage application to the motor starts due to the applied voltage is reduced. Therefore, even when there is variation in the starting voltage of the motor, the possibility that the air chamber is rapidly decompressed is reduced.

[0081] (C) In the liquid ejection device, the control unit may increase the applied voltage at a constant slope until a predetermined time has elapsed after starting to apply voltage to the motor. According to the above configuration, even when there is variation in the starting voltage of the motor, the possibility that the air chamber is rapidly decompressed is reduced.

[0082] (D) In the liquid ejection device, the control unit may increase the slope of the applied voltage after the predetermined time has elapsed. According to the above configuration, compared with the case where the slope of the applied voltage remains constant, the time until the applied voltage reaches the target voltage is shortened.

[0083] (E) In the above liquid ejection device, the control unit may increase the slope of the applied voltage and then maintain the applied voltage at a relay voltage lower than the target voltage for a certain period of time. When the slope of the applied voltage increases, there is a risk that the air chamber will be rapidly depressurized. In this case, there is a risk that air will flow into the ejection part from the nozzle. In this regard, according to the above configuration, since the applied voltage is maintained at the relay voltage for a certain period of time, the risk that the air chamber will be rapidly depressurized is reduced.

[0084] (F) The above liquid ejection device includes a movable body on which the ejection part is mounted, a supply flow path through which the liquid supplied to the ejection part flows, and a flow part mounted on the movable body and connected to the supply flow path and the ejection part. The flow part may have the housing part. According to the above configuration, the flow of the liquid supplied to the ejection part can be controlled by the housing part.

[0085] (G) The above liquid ejection device includes a movable body on which the ejection part is mounted, a supply flow path through which the liquid supplied to the ejection part flows, and a flow part mounted on the movable body and connected to the supply flow path and the ejection part. The housing part may be located in the supply flow path. According to the above configuration, the liquid in the ejection part can be returned to the supply flow path.

[0086] (H) In the above liquid ejection device, the flow part has a regulating valve located upstream of the housing part. The regulating valve is configured to open when the pressure in the liquid chamber becomes equal to or lower than a predetermined pressure, and the predetermined pressure may be higher than the pressure resistance of the meniscus formed at the nozzle. According to the above configuration, the regulating valve opens before the pressure in the liquid chamber falls below the pressure resistance of the meniscus. Therefore, the risk that air will flow into the ejection part from the nozzle is reduced.

[0087] (I) The control method of the liquid ejection device includes a discharge unit that discharges liquid from a nozzle, a supply flow path through which the liquid supplied to the discharge unit flows, and a flow control unit that is connected to the supply flow path and the discharge unit and controls the flow of the liquid supplied to the discharge unit. The control method further includes a pressure variable unit connected to the flow control unit and a control unit that controls the pressure variable unit. The flow control unit includes a membrane member that divides the flow space in the flow control unit into an air chamber and a liquid chamber, and a regulating valve located upstream of the liquid chamber. The liquid chamber communicates with the discharge unit, and the air chamber communicates with the pressure variable unit. The pressure variable unit includes a vacuum pump that decompresses the air chamber and a motor that drives the vacuum pump. The regulating valve is configured to open when the pressure in the liquid chamber becomes equal to or lower than a predetermined pressure. The control method includes gradually increasing the applied voltage to the motor until the applied voltage reaches a target voltage. According to the above method, the same effect as the above-described liquid ejection device can be obtained.

[0088] (J) The control method of the liquid ejection device may include increasing the applied voltage from a voltage lower than the starting voltage of the motor. According to the above method, the same effect as the above-described liquid ejection device can be obtained.

Description of Reference Numerals

[0089] 11…Liquid ejection device, 12…Liquid ejection unit, 13…Liquid container, 14…Ejection part, 15…Nozzle surface, 16…Nozzle, 17…Accommodation part, 18…Membrane member, 21…Flow part, 22…Adjustment valve, 23…On-off valve, 24…Pressurization part, 25…Flow member, 26…Choke membrane, 27…Valve part, 28…Operation part, 29…Lever, 30…Shaft part, 31…First part, 32…Second part, 33…Pressurization membrane, 34…Pressurization member, 36…Moving body, 41…Liquid supply unit, 42…Supply flow path, 43…Supply valve, 44…Flow path pump, 45…Diaphragm, 46…Pressing member, 47…Pressure variable unit, 48…Vacuum pump, 49…Motor, 50…Air flow path, 51…First air valve, 52…Second air valve, 53…Third air valve, 54…Atmospheric release valve, 56…Power supply circuit, 57…Control unit, C1…Liquid chamber, C11…Flow path liquid chamber, C12…Flow path air chamber, C2…Air chamber, C3…Choke space, C4…Pressurization space, C5…Choke liquid chamber, C6…Choke air chamber, C7…Pressurization liquid chamber, C8…Pressurization air chamber, H1…Inlet, H2…Outlet, H3…Air port, H4…Choke inlet, H5…Choke outlet, H6…Choke air port, H7…Pressurization inlet, H8…Pressurization outlet, H9…Pressurization air port, M1…Medium.

Claims

1. A discharge part that discharges liquid from a nozzle, A housing part connected to the discharge part, A pressure variable unit connected to the housing part, A control unit that controls the pressure variable unit, and is provided with, The housing part has a film member that partitions the inside of the housing part into an air chamber and a liquid chamber, The liquid chamber communicates with the discharge part, The air chamber communicates with the pressure variable unit, The pressure variable unit, A decompression pump that decompresses the air chamber, A motor that drives the decompression pump, and has, The control unit gradually increases the applied voltage until the applied voltage of the motor reaches a target voltage, and is characterized in that it is a liquid discharge device.

2. The control unit increases the applied voltage from a voltage lower than the starting voltage of the motor, and is characterized in that it is the liquid discharge device according to claim 1.

3. The control unit increases the applied voltage at a constant slope until a predetermined time has elapsed after starting to apply a voltage to the motor, and is characterized in that it is the liquid discharge device according to claim 2.

4. After the predetermined time has elapsed, the control unit increases the slope of the applied voltage, and is characterized in that it is the liquid discharge device according to claim 3.

5. After increasing the slope of the applied voltage, the control unit maintains the applied voltage at a relay voltage lower than the target voltage for a certain period of time, and is characterized in that it is the liquid discharge device according to claim 4.

6. A movable body on which the discharge part is mounted and movable, A supply flow path through which the liquid supplied to the discharge part flows, A fluid part mounted on the movable body and connected to the supply flow path and the discharge part, and is provided with, The liquid discharge device according to claim 1, wherein the flow portion has the housing portion.

7. A moving body on which the discharge portion is mounted and is movable, A supply flow path through which the liquid supplied to the discharge portion flows, A flow portion mounted on the moving body and connected to the supply flow path and the discharge portion, The liquid discharge device according to claim 1, wherein the housing portion is located in the supply flow path.

8. The flow portion has a regulating valve located upstream of the housing portion, The regulating valve is configured to open when the pressure in the liquid chamber becomes equal to or lower than a predetermined pressure, The liquid discharge device according to claim 6, wherein the predetermined pressure is greater than the pressure resistance of the meniscus formed in the nozzle.

9. A discharge portion that discharges liquid from a nozzle, A supply flow path through which the liquid supplied to the discharge portion flows, A flow portion connected to the supply flow path and the discharge portion and controlling the flow of the liquid supplied to the discharge portion, A pressure variable unit connected to the flow portion, A control unit that controls the pressure variable unit, The flow portion, A membrane member that partitions the flow space in the flow portion into an air chamber and a liquid chamber, A regulating valve located upstream of the liquid chamber, The liquid chamber communicates with the discharge portion, The air chamber communicates with the pressure variable unit, The pressure variable unit, A decompression pump that decompresses the air chamber, A motor that drives the decompression pump, A control method for a liquid discharge device, wherein the regulating valve is configured to open when the pressure in the liquid chamber becomes equal to or lower than a predetermined pressure, A method for controlling a liquid ejection device, comprising gradually increasing an applied voltage until the applied voltage applied to the motor reaches a target voltage.

10. The method for controlling a liquid ejection device according to claim 9, comprising increasing the applied voltage from a voltage lower than a starting voltage of the motor.

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