Liquid dispensing device

Abstract

To prevent pigment settling in the damper. [Solution] A liquid ejection device according to the present disclosure includes a head having a nozzle row that ejects liquid, and a damper having a storage chamber that stores the liquid and supplies the liquid from the storage chamber to the nozzle row. The damper is configured so that the volume of the storage chamber changes depending on the pressure of the liquid. The liquid ejection device repeats a pressurization process that pressurizes the liquid in the damper and a depressurization process that depressurizes the liquid in the damper.

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection device. [Background technology]

[0002] Patent Document 1 describes an image forming apparatus equipped with an ink supply system that supplies ink to a head, and also describes a damper device that reduces pressure fluctuations in the ink supplied to the head and stabilizes the ink ejection operation from the nozzles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-156855 Summary of the Invention [Problem to be solved by the invention]

[0004] In the damper that stores the liquid (ink), the pigment in the liquid may settle.

[0005] The present invention aims to suppress the settling of pigments in a damper. [Means for solving the problem]

[0006] The main invention to achieve the above object is: a head having a nozzle array that ejects liquid; a damper having a storage chamber for storing the liquid and supplying the liquid in the storage chamber to the nozzle row; Equipped with The damper is configured so that the volume of the storage chamber changes in response to the pressure of the liquid, A pressurizing process for pressurizing the liquid in the damper and a depressurizing process for depressurizing the liquid in the damper are repeated. The liquid ejection device is characterized by the above.

[0007] Other features of the present invention will become apparent from the description of this specification. [Effects of the Invention]

[0008] According to the present invention, it is possible to suppress the settling of pigments in the damper. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic explanatory diagram of a liquid ejection device 1. As shown in FIG. [Figure 2] FIG. 2 is a block diagram of the liquid ejection device 1. As shown in FIG. [Figure 3] FIG. 3 is an explanatory diagram of the head 20. [Figure 4] FIG. 4 is an explanatory diagram of the supply unit 30. [Figure 5] Fig. 5A is an explanatory diagram of the damper 32. Fig. 5B is an explanatory diagram of the state of the damper 32 during pressurization processing. Fig. 5C is an explanatory diagram of the state of the damper 32 during depressurization processing. [Figure 6] FIG. 6 is a flow diagram of the stirring process. [Figure 7] FIG. 7 is an explanatory diagram of a supply unit according to a first modified example. [Figure 8] FIG. 8 is a flow diagram of the stirring process of the first modified example. [Figure 9] FIG. 9 is an explanatory diagram of a supply unit according to a second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] === Implementation form === <Basic configuration> Fig. 1 is a schematic explanatory diagram of a liquid ejection device 1. Fig. 2 is a block diagram of the liquid ejection device 1.

[0011] The liquid ejection device 1 is a device that ejects liquid onto a medium M (printing paper, printing film, etc.). Here, the liquid ejection device 1 is a device (inkjet printer) that prints an image onto the medium M. However, the liquid ejection device 1 does not have to be a device that prints an image onto the medium M, as long as it is a device that ejects liquid from the head 20. In other words, the liquid ejected from the head 20 is not limited to ink. The liquid ejection device 1 has a moving unit 10 (carriage unit 11 and transport unit 12), the head 20, a supply unit 30, a cleaning unit 40 (cap unit 41 and wiper unit 42), and a controller 50.

[0012] The moving unit 10 is a unit that moves at least one of the medium M and the head 20. Here, the moving unit 10 has a carriage unit 11 and a transport unit 12. The carriage unit 11 is a unit that moves a carriage 111 carrying the head 20 in the scanning direction. The transport unit 12 is a unit that transports the medium M in the transport direction. Note that the moving unit 10 is not limited to having the carriage unit 11 and the transport unit 12. For example, the moving unit 10 may be configured with a carriage unit 11 that moves the carriage 111 in two dimensions relative to the fixed medium M. The moving unit 10 may also be configured with a transport unit 12 that transports the medium M relative to the fixed head 20.

[0013] FIG. 3 is an explanatory diagram of the head 20. The head 20 has multiple nozzle rows 21 that eject liquid. The head 20 in the figure has four nozzle rows 21 (21C, 21M, 21Y, 21W). Here, the nozzle rows 21 that eject liquids of different colors (here, inks) are provided, including color ink nozzle rows (cyan ink nozzle row 21C, magenta ink nozzle row 21M, yellow ink nozzle row 21Y) that eject color inks (cyan ink, magenta ink, yellow ink), and a white ink nozzle row 21W that ejects white ink. The number of nozzle rows 21 is not limited to four and may be any other number. For example, the head 20 may further include a black ink nozzle row. Also, multiple nozzle rows 21 that eject ink of the same color may be provided. For example, two or more white ink nozzle rows 21W may be provided. Each nozzle row 21 has multiple nozzles 211 lined up in the transport direction. The nozzles 211 are open in the nozzle surface 22 of the head 20 (the lower surface of the head 20), and liquid is ejected from the openings.

[0014] Each nozzle 211 is provided with a discharge drive unit (not shown). For example, the discharge drive unit is configured with a piezoelectric element. When the discharge drive unit is driven, droplets are discharged from the nozzle 211. Note that the discharge drive unit is not limited to a piezoelectric element, and may be configured with, for example, a heater.

[0015] The supply unit 30 is a unit for supplying liquid to the nozzle rows 21 of the head 20. The configuration and operation of the supply unit 30 will be described later.

[0016] The cleaning unit 40 is a unit for cleaning the head 20. The cleaning unit 40 has a cap unit 41 and a wiper unit 42 (see FIG. 2). The cap unit 41 has a cap that covers the nozzle surface 22 of the head 20. By covering the nozzle surface 22 of the head 20 with the cap when the liquid ejection device 1 is stopped, the liquid inside the nozzles 211 is prevented from drying out. The wiper unit 42 has a wiper for wiping the nozzle surface 22 of the head 20.

[0017] The controller 50 is a control unit that controls the liquid ejection device 1. The controller 50 controls each unit of the liquid ejection device 1 (movement unit 10, head 20, supply unit 30, cleaning unit 40). The controller 50 has an arithmetic processing unit and a storage device (not shown). The arithmetic processing unit is composed of, for example, a CPU, an MPU, etc. The storage device has RAM used to execute programs, ROM for storing programs, etc. The arithmetic processing unit executes the programs stored in the storage device, thereby performing various processes (printing process, stirring process, etc.). Figure 2 shows functional blocks of the controller 50. The controller 50 has a print processing unit 51 and a stirring processing unit 52.

[0018] The print processing unit 51 performs processing (print processing) for printing on the medium M. For example, the print processing unit 51 alternately repeats a liquid ejection operation in which the carriage unit 11 is driven to move the head 20 in the scanning direction while ejecting liquid from the head 20, and a transport operation in which the transport unit 12 is driven to transport the medium M in the transport direction, thereby printing an image on the medium M.

[0019] The agitation processing unit 52 performs a process (agitation process) for agitating the liquid (ink in this case). The agitation process will be described later.

[0020] <About the supply unit> FIG. 4 is an explanatory diagram of the supply unit 30.

[0021] The supply unit 30 is a unit for supplying liquid (ink in this case) to the nozzle rows 21 of the head 20. As will be described later, the supply unit 30 also agitates the liquid. A supply unit 30 is provided for each nozzle row 21. When the head 20 has four nozzle rows 21 as shown in FIG. 3, the liquid ejection device 1 will have four supply units 30 (four systems).

[0022] 4 shows a supply unit 30 that supplies liquid to a certain nozzle row 21 (only one supply unit 30 is shown). Supply units that supply liquid to other nozzle rows 21 are not shown, but the supply units that supply liquid to other nozzle rows 21 also have the same configuration as the supply unit 30 in the figure. In this example, the liquid ejection device 1 is equipped with four supply units 30 shown in FIG. 4. Note that the supply units that supply liquid to other nozzle rows 21 may have a different configuration from the supply unit 30 in the figure (described below; see FIG. 9).

[0023] The supply unit 30 includes a tank 31 , a damper 32 , a supply control valve 33 , a liquid feed pump 34 A, a pressure reducing pump 35 , a pressure sensor 36 , a supply path 37 , a recovery path 38 , and a circulation path 39 .

[0024] The tank 31 is a supply source of liquid (ink in this case). The tank 31 is formed of, for example, an ink cartridge. The liquid in the tank 31 is supplied to a predetermined nozzle row 21 of the head 20 via a damper 32. The tank 31 is provided in the main body of the liquid ejection device 1 (see FIG. 1). Meanwhile, the damper 32 and the head 20 are mounted on a carriage 111.

[0025] FIG. 5A is an explanatory diagram of the damper 32. The damper 32 is a member for reducing pressure fluctuations in the liquid supplied to the head 20 (nozzle row 21). The damper 32 has a storage chamber 32A that stores the liquid, and a damper membrane 32B. The damper membrane 32B is a membrane-like member that can be elastically deformed, and forms one side of the storage chamber 32A. The elastic deformation of the damper membrane 32B can reduce pressure fluctuations in the liquid.

[0026] Fig. 5B is an explanatory diagram of the state of the damper 32 during pressurization processing, and Fig. 5C is an explanatory diagram of the state of the damper 32 during depressurization processing. As will be described later, in this embodiment, a pressurization process is performed to pressurize the liquid in the damper 32, and a decompression process is performed to decompress the liquid in the damper 32. The volume of the damper 32 (the volume of the storage chamber 32A) changes as the damper membrane 32B elastically deforms. As shown in FIG. 5B, when the pressure of the liquid in the damper 32 increases, the damper membrane 32B expands outward, and the volume of the damper 32 increases. As shown in FIG. 5C, when the pressure of the liquid in the damper 32 decreases, the damper membrane 32B contracts inward, and the volume of the damper 32 decreases.

[0027] As shown in FIG. 4, the damper 32 has an inlet 321, a supply port 322, and an outlet 323. The inlet 321 is an opening for allowing the liquid supplied from the tank 31 to flow into the storage chamber 32A. The inlet 321 is connected to the second supply path 37B. The supply port 322 is an opening for supplying the liquid in the storage chamber 32A to the head 20 (nozzle row 21). The supply port 322 is connected to the head 20. The outlet 323 is an opening for discharging the liquid in the storage chamber 32A to the outside. The outlet 323 is connected to the recovery path 38.

[0028] The supply control valve 33 is a valve disposed between the tank 31 and the first supply path 37A. When the supply control valve 33 is opened, the tank 31 and the first supply path 37A are connected, allowing the liquid to be supplied from the tank 31. When the supply control valve 33 is closed, the tank 31 and the first supply path 37A are blocked, and the supply of the liquid from the tank 31 is stopped. The supply control valve 33 may be provided at the supply port of the tank 31, or may be provided on the supply path downstream of the supply port of the tank 31 (between the tank 31 and the branch point of the first supply path 37A and the circulation path 39). The opening and closing of the supply control valve 33 is controlled by the controller 50.

[0029] The liquid feed pump 34A is a pump for feeding liquid from the tank 31 to the head 20 (nozzle array 21). The liquid feed pump 34A also feeds liquid from the tank 31 to the damper 32. The liquid feed pump 34A is disposed between the first supply path 37A and the second supply path 37B. When the liquid feed pump 34A is driven, the liquid is fed from the first supply path 37A to the second supply path 37B. When the liquid feed pump 34A is driven, the liquid in the damper 32 is pressurized. Therefore, the liquid feed pump 34A also functions as a pressure pump (pressurization mechanism) that pressurizes the liquid in the damper 32. Note that the liquid feed pump 34A may be driven in the reverse direction to depressurize the liquid in the damper 32. When the liquid feed pump 34A is stopped, the flow of fluid in the second supply path 37B is stopped. The liquid feed pump 34A is controlled by the controller 50. The liquid feed pump 34A is provided in the main body of the liquid discharger 1.

[0030] The decompression pump 35 is a pump for sucking out the liquid inside the damper 32. The decompression pump 35 has the function of reducing the pressure of the liquid inside the damper 32. The decompression pump 35 is disposed between the recovery path 38 and the circulation path 39. When the decompression pump 35 is driven, the liquid is sent from the recovery path 38 to the circulation path 39. When the decompression pump 35 stops, the flow of fluid in the recovery path 38 and the circulation path 39 stops. The decompression pump 35 is controlled by a controller 50. The decompression pump 35 is provided in the main body of the liquid discharger 1.

[0031] The pressure sensor 36 measures the pressure of the liquid in the damper 32 (storage chamber 32A). The pressure sensor 36 outputs the measurement result to the controller 50. The controller 50 controls the supply unit 30 (supply control valve 33, liquid feed pump 34A, and pressure reduction pump 35) based on the measurement result of the pressure sensor 36. The pressure sensor 36 is provided in the damper 32 (storage chamber 32A). Therefore, the pressure sensor 36 is mounted on the carriage 111 together with the damper 32. Note that, although the pressure sensor 36 in the drawing directly measures the pressure of the liquid in the damper 32, the pressure sensor 36 is not limited to this. For example, the pressure sensor 36 may be configured to indirectly measure the pressure of the liquid in the damper 32 by measuring the amount of elastic deformation of the damper membrane 32B.

[0032] The supply path 37 is a flow path for supplying liquid from the tank 31 to the damper 32. The supply path 37 has a first supply path 37A and a second supply path 37B.

[0033] The first supply path 37A is a flow path from the tank 31 to the liquid feed pump 34A. One end (upstream end) of the first supply path 37A is connected to the supply port of the tank 31, and the other end (downstream end) is connected to the liquid feed pump 34A. An end of a circulation path 39 is connected to the first supply path 37A.

[0034] The second supply path 37B is a flow path from the liquid feed pump 34A to the damper 32. One end (upstream end) of the second supply path 37B is connected to the liquid feed pump 34A, and the other end (downstream end) is connected to the inlet 321 of the damper 32. The second supply path 37B serves as a flow path for sending fluid from the liquid feed pump 34A on the main body side to the damper 32 on the carriage 111 side.

[0035] The recovery path 38 is a flow path for recovering liquid from the damper 32. The recovery path 38 is a flow path through which the liquid sucked out of the damper 32 by the decompression pump 35 flows. One end (upstream end) of the recovery path 38 is connected to the outlet 323 of the damper 32, and the other end (downstream end) is connected to the decompression pump 35. The recovery path 38 is a flow path for sending fluid from the damper 32 on the carriage 111 side to the decompression pump 35 on the main body side.

[0036] The circulation path 39 is a flow path for returning the liquid recovered from the damper 32 to the supply path 37. One end (upstream end) of the circulation path 39 is connected to the pressure reducing pump 35, and the other end (downstream end) is connected to the first supply path 37A. The liquid recovered from the damper 32 returns to the supply path 37 through the circulation path 39 and is supplied to the damper 32 again through the supply path 37.

[0037] During the printing process in which liquid is ejected from the head 20 to print on the medium M, the controller 50 (print processing unit 51) supplies the liquid (ink in this case) from the tank 31 to the head 20 (damper 32) and maintains the liquid in the damper 32 at a predetermined pressure. During the printing process, the controller 50 opens the supply control valve 33, drives the liquid feed pump 34A, and stops the pressure reduction pump 35 to supply the liquid from the tank 31 to the head 20 (damper 32). The controller 50 also drives the liquid feed pump 34A based on the pressure sensor 36 so that the liquid surface (ink meniscus) in the nozzle 211 becomes concave and the liquid in the damper 32 (storage chamber 32A) is maintained at a predetermined pressure (normal pressure).

[0038] <About the mixing process> If liquid continues to be stored in the damper 32 (storage chamber 32A), there is a risk that the pigment in the liquid (ink in this case) will settle inside the damper 32. Settling of the pigment inside the damper 32 may cause malfunctions of the supply unit or the head 20. In particular, when the liquid is white ink, the pigment in white ink tends to settle significantly, so settling of the pigment inside the damper 32 becomes a problem. In this embodiment, the liquid ejection device 1 performs a stirring process to prevent settling of the pigment inside the damper 32.

[0039] FIG. 6 is a flow diagram of the agitation process. The various processes (pressurization process, depressurization process, etc.) shown in the figure are performed by the arithmetic processing device constituting the controller 50 executing a program stored in the storage device. The controller 50 performs the agitation process shown in the figure, for example, when the nozzle surface 22 of the head 20 remains covered by the cap of the cap unit 41 for a predetermined period of time. However, the controller 50 may also perform the agitation process while performing the printing process. As will be described next, the controller 50 repeatedly performs the pressurization process and the depressurization process during the agitation process.

[0040] First, the controller 50 (agitation processing unit 52; pressure processing unit 521) performs a pressure application process (S001). The pressure application process is a process of pressurizing the liquid inside the damper 32 (storage chamber 32A). During the pressure application process, the controller 50 opens the supply control valve 33, drives the liquid feed pump 34A, and stops the decompression pump 35. By driving the liquid feed pump 34A with the supply control valve 33 open and the decompression pump 35 stopped, the liquid flows into the damper 32. During the pressure application process, the liquid inside the damper 32 is pressurized by the liquid flowing into the damper 32. During the pressure application process, the damper membrane 32B bulges outward, and the volume of the damper 32 increases, as shown in FIG. 5B.

[0041] During the pressurization process, the controller 50 drives the liquid feed pump 34A so that the measurement result of the pressure sensor 36 becomes the first pressure. The first pressure during the pressurization process is set higher than the normal pressure (the pressure of the liquid inside the damper 32 when the liquid is ejected from the head 20; the pressure that causes the ink meniscus to become concave). On the other hand, if the pressure of the liquid inside the damper 32 is too high, the liquid may leak from the nozzles 211 onto the nozzle surface 22 and drip from the nozzle surface 22. Therefore, the first pressure is set to a pressure that prevents the liquid from leaking from the nozzles 211 onto the nozzle surface 22. In other words, the first pressure is set to a pressure lower than the pressure of the liquid inside the damper 32 when the liquid leaks from the nozzles 211 onto the nozzle surface 22 (the leakage pressure). When the measurement result of the pressure sensor 36 during the pressurization process reaches the first pressure, the controller 50 stops driving the liquid feed pump 34A. This prevents the pressure of the liquid inside the damper 32 from becoming too high.

[0042] After the pressurization process, the controller 50 (agitation processing unit 52; decompression processing unit 522) performs a decompression process (S002). The decompression process is a process for decompressing the liquid inside the damper 32 (storage chamber 32A). During the decompression process, the controller 50 opens the supply control valve 33, stops the liquid feed pump 34A, and drives the decompression pump 35. By driving the decompression pump 35 with the supply control valve 33 open and the liquid feed pump 34A stopped, the liquid is sucked from the damper 32 to the recovery path 38 (and the liquid flows from the circulation path 39 into the first supply path 37A). During the decompression process, the liquid inside the damper 32 is decompressed by being sucked from the damper 32 to the recovery path 38. During the decompression process, as shown in FIG. 5C, the damper membrane 32B is recessed inward, and the volume of the damper 32 decreases.

[0043] During the decompression process, the controller 50 drives the decompression pump 35 so that the measurement result of the pressure sensor 36 becomes the second pressure. The second pressure during the decompression process is set to a pressure lower than the normal pressure. On the other hand, if the pressure of the liquid in the damper 32 is too low, air may flow into the nozzle 211. Therefore, the second pressure is set to a pressure that prevents air from flowing into the nozzle 211. In other words, the second pressure is set to a pressure higher than the pressure of the liquid in the damper 32 when air flows into the nozzle 211 (air inflow pressure). When the measurement result of the pressure sensor 36 during the decompression process reaches the second pressure, the controller 50 stops driving the decompression pump 35. This prevents the pressure of the liquid in the damper 32 from becoming too low.

[0044] The controller 50 alternately repeats the pressurization process and the depressurization process multiple times (NO in S003). As a result, the damper membrane 32B reciprocates, the damper 32 repeatedly increases and decreases in volume, and the damper 32 (storage chamber 32A) pulsates. This agitates the liquid in the damper 32, making it possible to suppress sedimentation of the pigment in the damper 32. Note that in this embodiment, the volume of the damper 32 is changed by reciprocating the damper membrane 32B. This makes it easier for the liquid to flow in the damper 32 (in other words, makes it harder for the liquid to stagnate in the damper 32) compared to when the liquid in the storage chamber 32A, whose volume does not change, is repeatedly pressurized and depressurized. This makes it possible to further suppress sedimentation of the pigment.

[0045] The controller 50 alternately repeats pressurization and depressurization processes every one to several seconds. However, the repetition period of the pressurization and depressurization processes is not limited to this. If the repetition period of the pressurization and depressurization processes is too fast, the change in the volume of the damper 32 will be small, making it difficult to agitate the liquid. For this reason, the repetition period of the pressurization and depressurization processes is set to a period that can cause the damper membrane 32B to reciprocate greatly and can change the volume of the damper 32 greatly.

[0046] The period of the pressurization treatment and the period of the depressurization treatment may be constant. When the period of the pressurization treatment and the period of the depressurization treatment are constant, the stirring treatment performed by the controller 50 can be simplified. On the other hand, the controller 50 may change the duration of the pressurization treatment or depressurization treatment each time the pressurization treatment or depressurization treatment is repeated. Changing the duration of the pressurization treatment or depressurization treatment changes the flow of the liquid inside the damper 32, making it possible to further suppress the settling of the pigment. The pressurization period and the depressurization period may be the same length or different lengths.

[0047] As already explained, the damper 32 is provided with an inlet 321 and an outlet 323. Therefore, during a pressurization process, the liquid flows into the damper 32 from the inlet 321, and during a depressurization process, the liquid is sucked out from the outlet 323, which is located separately from the inlet 321. By providing the inlet 321 through which the liquid enters the damper 32 during a pressurization process and the outlet 323 through which the liquid flows out of the damper 32 during a depressurization process separately, it is possible to prevent the liquid from accumulating inside the damper 32 compared to when the liquid flows in and out at the same location, and a structure that makes it easier to agitate the liquid is achieved.

[0048] Furthermore, if the structure were such that liquid flows in and out of the same inlet and outlet of damper 32, the liquid that has just been sucked out of damper 32 during the decompression process would flow back into damper 32 during the pressurization process, making it difficult to sufficiently agitate the liquid. In contrast, by providing inlet 321 and outlet 323 in damper 32, it is possible to create a structure in which the liquid collected from outlet 323 does not flow back into damper 32, making it easier to agitate the liquid.

[0049] The controller 50 alternately repeats the pressurization process and the depressurization process until a predetermined condition is met, such as a predetermined number of times or a predetermined period of time (NO in S003). Then, when the predetermined condition is met (YES in S003), the controller 50 completes the stirring process.

[0050] <First Modification> In the above description, during the pressurization process, the liquid in the damper 32 is pressurized by the liquid feed pump 34A. However, the pressurization mechanism that pressurizes the liquid in the damper 32 is not limited to the liquid feed pump 34A (pressurization pump).

[0051] FIG. 7 is an explanatory diagram of a supply unit according to a first modified example.

[0052] The supply unit 30 of the first modified example includes a tank 31, a damper 32, a supply control valve 33, an on-off valve 34B, a pressure reducing pump 35, a pressure sensor 36, a supply path 37 (37A, 37B), a recovery path 38, and a circulation path 39. The tank 31, damper 32, supply control valve 33, pressure reducing pump 35, pressure sensor 36, supply path 37, recovery path 38, and circulation path 39 of the supply unit 30 of the first modified example are the same as those of the supply unit shown in Fig. 4, and therefore description thereof will be omitted here. The supply unit 30 of the first modified example includes an on-off valve 34B instead of the liquid feed pump 34A (pressurizing pump) described above.

[0053] The on-off valve 34B is a valve for opening and closing the supply path 37. The on-off valve 34B is disposed between the first supply path 37A and the second supply path 37B. When the on-off valve 34B is open, the first supply path 37A and the second supply path 37B are connected to each other. There is a head difference between the tank 31 and the damper 32 (head 20) (see FIG. 1). When the on-off valve 34B is opened while the supply control valve 33 is open, liquid can be supplied from the tank 31 to the damper 32. When the on-off valve 34B is opened while the supply control valve 33 is open, the liquid in the damper 32 is pressurized. Therefore, the on-off valve 34B also functions as a pressurizing mechanism for pressurizing the liquid in the damper 32. When the on-off valve 34B is closed even if the supply control valve 33 is open, the supply path 37 is shut off, and the supply of liquid to the damper 32 is stopped. The on-off valve 34B is controlled to open and close by the controller 50. The on-off valve 34B is provided in the main body of the liquid discharger 1.

[0054] FIG. 8 is a flow diagram of the stirring process of the first modified example.

[0055] In the first modified example, during the pressurization process, the controller 50 opens the supply control valve 33, opens the on-off valve 34B, and stops the decompression pump 35 (S001'). By opening the on-off valve 34B while the supply control valve 33 is open and the decompression pump 35 is stopped, the liquid flows into the damper 32. In the pressurization process of the first modified example as well, the liquid flows into the damper 32, and the liquid inside the damper 32 is pressurized. Also, in the pressurization process of the first modified example as well, the damper membrane 32B bulges outward, and the volume of the damper 32 increases, as shown in FIG. 5B .

[0056] Furthermore, in the first modified example, during the decompression process, the controller 50 opens the supply control valve 33, closes the on-off valve 34B, and drives the decompression pump 35 (S002'). By driving the decompression pump 35 with the supply control valve 33 open and the on-off valve 34B closed, the liquid is sucked out of the damper 32 into the recovery path 38 (and the liquid flows from the circulation path 39 into the first supply path 37A). In the decompression process of the first modified example, the liquid is sucked out of the damper 32 into the recovery path 38, thereby reducing the pressure inside the damper 32. In the decompression process of the first modified example, the damper membrane 32B also dents inward, reducing the volume of the damper 32, as shown in FIG. 5C .

[0057] In the first modified example, the controller 50 also alternately repeats the pressurization process (S001') and the depressurization process (S002') multiple times (NO in S003). This causes the damper membrane 32B to reciprocate, the damper 32 repeatedly increases and decreases in volume, and the damper 32 (storage chamber 32A) pulsates. This agitates the liquid in the damper 32, making it possible to suppress the settling of the pigment in the damper 32.

[0058] <Second Modification> In the above description, the supply units provided for the multiple nozzle rows 21 have the same configuration. However, the configuration of the supply unit for one nozzle row 21 may be different from the configuration of the supply unit for another nozzle row 21.

[0059] Figure 9 is an explanatory diagram of a supply unit of the second modified example. The figure shows a supply unit 30W that supplies white ink to the white ink nozzle row 21W (see Figure 3), and a supply unit 30C that supplies cyan ink to the cyan ink nozzle row 21C. Note that the supply unit that supplies magenta ink to the magenta ink nozzle row 21M and the supply unit that supplies yellow ink to the yellow ink nozzle row 21Y are not shown in Figure 9, but have the same configuration as the supply unit 30C for the cyan ink nozzle row 21C.

[0060] The supply unit 30W that supplies white ink to the white ink nozzle row 21W has the same configuration as the supply unit 30 shown in Figure 4 or Figure 7. The pressurizing mechanism 34 in Figure 9 is made up of a liquid feed pump 34A (see Figure 4) or an on-off valve 34B (see Figure 7), and has the function of sending liquid from the tank 31 to the damper 32 (head 20) and the function of pressurizing the liquid inside the damper 32. Because white ink has large pigments that tend to settle, the supply unit 30W that supplies white ink is configured to be able to perform the stirring process described above.

[0061] The supply unit 30C, which supplies cyan ink to the cyan ink nozzle row 21C, has a different configuration from the supply unit 30W. The supply unit 30C includes a tank 31, a damper 32, a supply control valve 33, a liquid feed pump 34A, a pressure sensor 36, and a supply path 37 (37A, 37B). The liquid feed pump 34A of the supply unit 30C has the function of feeding liquid (cyan ink in this case) from the tank 31 to the damper 32 (head 20), similar to the liquid feed pump 34A in FIG. 4. Note that in the supply unit 30C, an on-off valve 34B may be used instead of the liquid feed pump 34A.

[0062] The supply unit 30C does not include a decompression pump 35. Therefore, the supply unit 30C cannot perform the decompression process using the decompression pump 35, and therefore cannot perform the stirring process described above. However, since the pigment in cyan ink is less likely to settle than in white ink, it is permissible not to perform the stirring process on cyan ink. On the other hand, the supply unit 30C, which does not include a decompression pump 35, can be constructed more inexpensively than the supply unit 30W, which includes a decompression pump 35. Therefore, according to the second modification, the liquid ejection device 1 can be constructed inexpensively.

[0063] It is also possible to agitate the liquid in the damper 32 of the supply unit 30C by repeatedly driving the liquid feed pump 34A of the supply unit 30C in the forward direction to pressurize the liquid (cyan ink in this case) in the damper 32, and then driving the liquid feed pump 34A in the reverse direction to depressurize the liquid in the damper 32. In this case, however, the location (inlet 321) where the liquid enters the damper 32 during the pressurization process and the location (inlet 321) where the liquid leaves the damper 32 during the depressurization process are the same, and since the liquid simply flows in and out through the inlet 321 of the damper 32, it is thought that the liquid is more likely to stagnate in the damper 32 than in the agitation process described above. However, because the pigment in cyan ink is less likely to settle than in white ink, it is acceptable to perform an agitation process such as a depressurization process using the liquid feed pump 34A on cyan ink.

[0064] <Summary> The liquid ejection device 1 described above includes a head 20 having a nozzle row 21 that ejects liquid, and a damper 32 having a storage chamber 32A that stores liquid and supplies the liquid from the storage chamber 32A to the nozzle row 21. In this embodiment, the damper 32 is configured so that the volume of the storage chamber 32A changes depending on the pressure of the liquid (see FIGS. 5A to 5C), and the liquid ejection device 1 is configured to repeatedly perform a pressurization process that pressurizes the liquid in the damper 32 and a depressurization process that depressurizes the liquid in the damper 32 (see FIGS. 6 and 8). This makes it possible to agitate the liquid in the damper 32 and suppress sedimentation of the pigment.

[0065] Damper 32 also has inlet 321 (first opening) that allows liquid to flow into storage chamber 32A during pressurization, and outlet 323 (second opening) that discharges liquid from storage chamber 32A to the outside during depressurization. Providing inlet 321 (first opening) and outlet 323 (second opening) in different locations results in a structure that makes it easy to agitate the liquid.

[0066] The liquid discharger 1 also includes a pressurizing mechanism 34 (34A, 34B) that sends liquid to the damper 32 during pressurization, and a decompression pump 35 that sucks the liquid out of the damper 32 during decompression (see FIGS. 4, 7, and 9). This allows the liquid in the damper 32 to be agitated by repeatedly performing pressurization and decompression, thereby preventing pigment sedimentation. When pressurizing and decompression are performed by driving the liquid feed pump 34A forward and backward, the liquid simply flows in and out of the inlet 321 of the damper 32, which is likely to cause the liquid to stagnate in the damper 32. In contrast, decompression is performed using a decompression pump 35 that is provided separately from the pressurizing mechanism 34 used during pressurization, preventing the liquid from stagnating in the damper 32 and providing a structure that facilitates agitation of the liquid.

[0067] The pressurizing mechanism 34 is preferably configured by a liquid pump 34A (see FIG. 4). This makes it possible to increase the pressure of the liquid in the damper 32 compared to when the liquid in the damper 32 is pressurized using a head difference.

[0068] On the other hand, the pressurizing mechanism 34 may be configured with an on-off valve 34B (see FIG. 7). This allows for a simpler configuration than when a pump is used to pressurize the liquid inside the damper 32, and allows the liquid discharger 1 to be configured at low cost.

[0069] It is desirable that a damper 32 that supplies liquid to a certain nozzle row 21 (first nozzle row) is provided with a pressure reduction pump 35, and that a damper 32 that supplies liquid to another nozzle row 21 (second nozzle row) is not provided with a pressure reduction pump 35 (see FIG. 9). This allows the liquid ejection device 1 to be configured inexpensively. Note that in the above explanation, a pressure reduction pump 35 is provided to the damper 32 of the white ink nozzle row 21W (corresponding to the first nozzle row) and a pressure reduction pump 35 is not provided to the damper 32 of the cyan ink nozzle row 21C (corresponding to the second nozzle row), but the first nozzle row is not limited to the white ink nozzle row 21W, and the second nozzle row is not limited to the cyan ink nozzle row 21C.

[0070] ===Other embodiments=== The above-described embodiments are presented as examples and do not limit the scope of the invention. The above configurations can be implemented in appropriate combinations, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The above-described embodiments and their modifications are included in the scope and spirit of the invention, as well as in the inventions described in the claims and their equivalents. [Explanation of symbols]

[0071] 1 liquid ejection device, 10 moving unit, 11 carriage unit, 111 carriage, 12 transport unit, 20 head, 21 nozzle row, 211 nozzle, 22 nozzle surface, 30 supply units, 31 tanks, 32 damper, 32A reservoir chamber, 32B damper membrane, 321 Inflow port (first opening), 322 Supply port, 323 Outflow port (second opening), 33 supply control valve, 34 pressurizing mechanism, 34A Liquid transfer pump, 34B On-off valve, 35 pressure reducing pump, 36 pressure sensor, 37 supply route, 37A first supply route, 37B second supply route, 38 Recovery route, 39 Circulation route, 40 cleaning units, 41 Cap unit, 42 Wiper unit, 50 controller, 51 print processing unit, 52 agitation processing section, 521 pressure processing section, 522 decompression processing section, M medium

Claims

1. a head having a nozzle array that ejects liquid; a damper having a storage chamber for storing the liquid and supplying the liquid in the storage chamber to the nozzle row; Equipped with The damper is configured so that the volume of the storage chamber changes in response to the pressure of the liquid, A pressurizing process for pressurizing the liquid in the damper and a depressurizing process for depressurizing the liquid in the damper are repeated. A liquid ejection device characterized by:

2. The liquid ejection device according to claim 1 , The damper is a first opening that allows the liquid to flow into the storage chamber during the pressurization process; a second opening that is provided separately from the first opening and that discharges the liquid in the storage chamber to the outside during the decompression process; A liquid ejection device comprising:

3. 3. The liquid ejection device according to claim 1, a pressurizing mechanism that sends the liquid to the damper during the pressurizing process; a decompression pump that sucks out the liquid in the damper during the decompression process; A liquid ejection device comprising:

4. The liquid ejection device according to claim 3, The liquid ejection device is characterized in that the pressurizing mechanism is constituted by a pump.

5. The liquid ejection device according to claim 3, The liquid ejection device is characterized in that the pressurizing mechanism is constituted by an on-off valve.

6. The liquid ejection device according to claim 3, the head includes a first nozzle row that ejects a first liquid and a second nozzle row that ejects a second liquid that is different from the first liquid; the decompression pump is provided in a damper that supplies the first liquid to the first nozzle row, The liquid ejection apparatus is characterized in that the damper that supplies the second liquid to the second nozzle row is not provided with the decompression pump.

7. 3. The liquid ejection device according to claim 1, a pressure of the liquid in the damper during the pressurization process is higher than a pressure of the liquid in the damper when the liquid is ejected from the head, The liquid ejection device according to claim 1, wherein the pressure of the liquid inside the damper during the decompression process is lower than the pressure of the liquid inside the damper when the liquid is ejected from the head.

Images