Cap unit and liquid discharge device

Abstract

To provide a cap unit that can prevent moisturizing effect of a liquid in a nozzle from decreasing due to decrease in moisture content of the liquid in a cap unit when capping, and a liquid discharge device.SOLUTION: A cap unit 41 contacts a nozzle surface 28 of a liquid discharge part 20, thereby forming a space S where a nozzle opens. The cap unit 41 has a space formation part 71, a liquid storage part 72, a partition wall 75, a communication passage 76, an absorber 74 and a first discharge port 77. The space formation part 71 forms the space S. The liquid storage part 72 is provided below the space formation part 71, and can store a liquid IL. The partition wall 75 has gas permeability, and partitions the space formation part 71 and the liquid storge part 72. The communication passage 76 communicates the space formation part 71 and the liquid storage part 72 separately from the partition wall 75. The absorber 74 is provided in the space formation part 71, and can absorb the liquid. The first discharge port 77 communicates the interior and the exterior of the liquid storage part 72.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a cap unit capable of forming a space by coming into contact with a nozzle face of a liquid ejection portion that ejects liquid, and a liquid ejection apparatus. [Background technology]

[0002] Patent Document 1 discloses a liquid ejection device equipped with a recording head (an example of a liquid ejection section) that ejects liquid. This liquid ejection device includes a cap (an example of a cap unit) that covers a nozzle forming surface (nozzle surface) where the nozzles of the recording head are opened. The cap seals the nozzle forming surface to form an enclosed space (an example of a space). The liquid ejection device includes a partition plate in the cap that partitions and forms an enclosed space for one or more nozzle rows based on the concentration of the moisturizing component of each ink ejected from each nozzle when the nozzle forming surface is sealed with the cap. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-69583 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the moisture in the liquid, such as ink, inside the cap evaporates and the concentration of the moisturizer in the liquid inside the cap increases, the moisturizer in the cap absorbs the moisture from the liquid inside the nozzle, which causes the liquid inside the nozzle to thicken, potentially resulting in ejection problems. [Means for solving the problem]

[0005] A cap unit that solves the above problem is a cap unit that can form a space in which the nozzle opens by contacting the nozzle surface of a liquid ejection section that can eject liquid in an ejection direction from a nozzle formed on the nozzle surface, and has a space forming section that forms the space, a liquid storage section that is provided below the space forming section and is capable of storing liquid, a partition that is gas permeable and separates the space forming section from the liquid storage section, a communicating passage that connects the space forming section and the liquid storage section separately from the partition, an absorbent that is provided in the space forming section and is capable of absorbing liquid, and a first exhaust port that connects the inside of the liquid storage section to the outside.

[0006] A liquid ejection device that solves the above problem includes a liquid ejection section capable of ejecting liquid in an ejection direction from nozzles formed on a nozzle face, the above-mentioned cap unit, and a suction mechanism capable of sucking the liquid through the first outlet.

[0007] A liquid ejection device that solves the above problem includes a liquid ejection section capable of ejecting liquid in an ejection direction from a nozzle formed on a nozzle face, the above-mentioned cap unit, and a suction mechanism capable of sucking the liquid through the first outlet and the second outlet. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing a liquid ejection device according to the first embodiment. [Diagram 2] FIG. 2 is a schematic front cross-sectional view showing the internal configuration of the liquid ejection device. [Diagram 3] FIG. 3 is a bottom view of the liquid ejection section. [Figure 4] FIG. 4 is a schematic diagram showing a liquid ejection unit and a maintenance unit. [Diagram 5] FIG. 5 is a perspective view showing the cap unit. [Figure 6] 6 is a cross-sectional view of the cap unit taken along line 6-6 in FIG. [Figure 7] 7 is a cross-sectional view of the cap unit taken along line 7-7 in FIG. [Figure 8] FIG. 8 is a perspective view of the cap unit with the absorbent body removed. [Figure 9] FIG. 9 is a perspective view showing a cap unit in the second embodiment. [Figure 10] 10 is a cross-sectional view of the cap unit taken along line 10-10 in FIG. [Figure 11] 11 is a cross-sectional view of the cap unit taken along line 11-11 in FIG. [Figure 12] FIG. 12 is a perspective view of the cap unit with the absorbent body removed. [Figure 13] FIG. 13 is a graph showing the relationship between the difference in moisturizer concentration and the moisture transfer rate. [Figure 14] FIG. 14 is a schematic cross-sectional view showing a modification of the cap unit of the first embodiment. [Figure 15] FIG. 15 is a schematic cross-sectional view showing a modification of the cap unit of the second embodiment. [Figure 16] FIG. 16 is a graph showing the relationship between the number of printed sheets and the concentration of moisturizer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A liquid ejection device and a control method thereof according to an embodiment will be described below with reference to the drawings. The liquid ejection device 11 shown in Fig. 1 is, for example, an inkjet printer that ejects ink, which is an example of a liquid, onto a medium M such as paper to record. In Fig. 1, the liquid ejection device 11 is placed on a horizontal plane, and the direction of gravity is indicated by the Z axis, and the directions along the horizontal plane are indicated by the X axis and the Y axis. The X axis, the Y axis, and the Z axis are perpendicular to each other.

[0010] As shown in FIG. 1, the liquid ejection device 11 may include a device main body 12, an image reading unit 13 that reads an image of a document, and an automatic feeder 14 that sends the document to the image reading unit 13. The liquid ejection device 11 may include an operation unit 15 that is operated by a user to give instructions to the liquid ejection device 11, a medium storage unit 16 that can store a medium M such as paper, and a stacker 17 that receives the medium M discharged after printing. The operation unit 15 may be, for example, a touch panel or a button, or a combination of these. The medium storage unit 16 can store multiple media M in a stacked state. The liquid ejection device 11 may include multiple medium storage units 16.

[0011] Next, the internal configuration of the liquid ejection device 11 will be described with reference to Fig. 2. As shown in Fig. 2, the device main body 12 has a housing 18 having a substantially rectangular parallelepiped shape. The liquid ejection device 11 includes, within the housing 18, a liquid ejection unit 20, a transport unit 30 that transports the medium M, a maintenance unit 40 that performs maintenance on the liquid ejection head 22, and a control unit 100 that controls the components including these.

[0012] The liquid ejection section 20 includes a liquid ejection head 22 having a plurality of nozzles 21 capable of ejecting liquid droplets, and a support section 23 that holds the liquid ejection head 22 at a predetermined height. The plurality of nozzles 21 are opened in a nozzle surface 28, which is a surface (e.g., a bottom surface) of the liquid ejection head 22 that faces a transport path along which the medium M is transported.

[0013] The liquid ejection head 22 ejects liquid onto the medium M. If the position at which the liquid ejection head 22 ejects liquid is defined as a recording position, then printing is performed by ejecting liquid from the nozzles 21 toward the medium M at the recording position. The liquid ejection head 22 of this embodiment is a line head having multiple nozzles 21 capable of simultaneously ejecting liquid across the entire width of the medium M in the width direction X that intersects (orthogonal in this embodiment) the transport direction Y and the vertical direction Z. The liquid ejection device 11 performs line printing by ejecting liquid from the multiple nozzles 21 located at positions facing the entire width of the medium M, which is transported at a constant speed corresponding to the print mode.

[0014] The liquid ejection head 22 is supported by the support portion 23 in a state in which it extends in a width direction X intersecting with the transport direction Y of the medium M. The liquid ejection head 22 is configured to eject liquid onto the medium M from a plurality of nozzles 21 constituting a plurality of nozzle groups. A supply flow path 25 for supplying liquid from the liquid container 24 is connected to the liquid ejection head 22. A plurality of liquid containers 24 are attached to a holder 26 in the housing 18. A liquid supply mechanism 25S is provided in the middle of the supply flow path 25 between the liquid container 24 and the liquid ejection unit 20. The liquid supply mechanism 25S has a function of supplying liquid and pressurizing the liquid to discharge a small amount of liquid from the nozzle 21 for maintenance. The liquid supply mechanism 25S controls the supply of liquid to the liquid ejection unit 20 and the pressurization of the liquid by generating pressurized air and controlling the air pressure.

[0015] The liquid containers 24 each contain a different type of liquid. In an example where the liquid is ink, the liquid containers 24 each contain ink of a different color. In this example, the liquid containers 24 each contain black ink and color ink. The liquid containers 24 each contain black, yellow, cyan, and magenta ink. Note that the black liquid container 24 may have a larger capacity than the liquid containers 24 of the other ink colors, as in the example shown in FIG. 2, and a plurality of liquid containers 24 (for example, two) may be attached. The number of liquid containers 24 is not limited to the five in the example shown in FIG. 2, and may be changed appropriately according to the number of ink colors, and may be 6 to 10, or 1 to 4.

[0016] The liquid container 24 is, for example, a liquid cartridge that is detachably attached to the holder 26, but may also be a liquid tank. In the case of a liquid tank, the liquid may be replenished by a user pouring liquid from a container such as a bottle.

[0017] The transport unit 30 includes a feed roller 31 that feeds the media M one by one from the group of media M stacked in the medium storage unit 16, starting from the top one, and a separation roller 32 that separates the media M one by one. The transport unit 30 further includes a plurality of transport rollers 33 that transport the media M along a transport path that is a path that passes through the recording position, and a transport belt 34 that transports the media M at the recording position. The transport belt 34 is wound around a first roller 35 and a second roller 36.

[0018] The conveyor belt 34 is configured to be rotatable about the first roller 35. The conveyor belt 34 is moved by a support portion moving mechanism 37 between a support position shown by a solid line in FIG. 2 and a retracted position shown by a two-dot chain line in FIG. 2. At the support position, the conveyor belt 34 supports the medium M being conveyed. That is, the conveyor belt 34 has the function of a support portion that supports the medium M so as to keep a constant gap between the medium M being conveyed and the liquid ejection head 22. Here, the conveying direction Y refers to the conveying direction of the medium M at the recording position.

[0019] The medium storage unit 16 is, for example, a cassette, and is removably inserted into a recess (not shown) formed in the housing 18. In the inserted state shown in Fig. 2, the medium M stored in the medium storage unit 16 is located inside the housing 18. Note that Fig. 2 shows only the topmost one of the multiple medium storage units 16, and the others are omitted.

[0020] The medium container 16 includes a movable edge guide 16A that is operated by a user. The medium M in the medium container 16 is positioned in the width direction by the edge guide 16A. The liquid ejection device 11 may include a size detection unit 19 shown in FIG. 2 that detects the size of the medium M contained in the medium container 16.

[0021] The liquid ejection device 11 includes a waste liquid container 50 that contains waste liquid generated during maintenance of the liquid ejection head 22. The waste liquid container 50 is detachably attached to a holder 51. The waste liquid container 50 attached to the holder 51 is disposed at a predetermined position within the housing 18.

[0022] The maintenance unit 40 performs maintenance of the liquid ejection head 22. Maintenance is performed to prevent or resolve ejection defects caused by clogging of the nozzles 21 or adhesion of foreign matter. Maintenance includes blank ejection and cleaning. Blank ejection is an ejection operation for maintenance that ejects droplets unrelated to printing from the nozzles 21 for the purpose of maintaining the liquid ejection head 22. Blank ejection is also called flushing. By performing blank ejection, thickened ink, etc. that causes ejection defects are discharged from the nozzles 21. By discharging thickened ink, etc., the inside of the nozzles 21 is replaced with fresh liquid. Cleaning resolves clogging of the nozzles 21 by forcibly discharging liquid from the nozzles 21.

[0023] The maintenance unit 40 includes a plurality of cap units 41 configured to cover a plurality of nozzle groups, a suction mechanism 44 that discharges liquid from within the cap units 41, and a cap moving mechanism 45 that moves the cap units 41. The suction mechanism 44 includes a waste liquid flow path 42 that connects the cap units 41 and the holder 51, and a pressure reducing unit 43 provided midway along the waste liquid flow path 42. The liquid ejection device 11 includes a waste liquid container 50 that stores the waste liquid discharged from the cap units 41 by the suction mechanism 44.

[0024] 1 and a capping position (shown by a two-dot chain line in FIG. 1) in contact with the nozzle surface 28 of the liquid ejection head 22. When the cap unit 41 moves to the capping position, the conveyor belt 34 retracts from the support position shown by a solid line in FIG. 2 to the retracted position shown by a two-dot chain line in FIG. 2.

[0025] Capping is performed by the cap unit 41 moving to the capping position and coming into contact with the nozzle surface 28 of the liquid ejection head 22 so as to surround the nozzles 21. When liquid ejection is not being performed, capping is performed to suppress thickening of the liquid inside the nozzles 21, thereby preventing ejection defects.

[0026] The liquid discharged as waste liquid from the nozzles 21 by idling is received in the cap unit 41. During flushing, maintenance, and when printing is completed, the cap unit 41 is placed in the capping position. Note that idling may be performed at the flushing position where the cap unit 41 is slightly separated from the nozzle surface 28.

[0027] Moreover, cleaning is performed by driving the decompression unit 43 with the cap unit 41 placed at the capping position. The cleaning in this example is suction cleaning in which the space formed between the nozzle surface 28 and the cap unit 41 is decompressed to a negative pressure when the cap unit 41 comes into contact with the nozzle surface 28, thereby forcibly sucking and discharging the liquid from the nozzles 21. A waste liquid flow path 42 is connected to one end of the cap unit 41 opposite the opening. The other end of the waste liquid flow path 42 is connected to a holder 51 via a decompression unit 43. The cap unit 41 is in communication with a waste liquid container 50 via the waste liquid flow path 42, the decompression unit 43, and the holder 51.

[0028] The liquid discharged from the nozzles 21 to the cap unit 41 by cleaning is collected as waste liquid from the cap unit 41 through the waste liquid flow path 42 into the waste liquid container 50. When a predetermined amount of waste liquid discharged from the nozzles 21 by idle discharge accumulates in the cap unit 41, the liquid in the cap unit 41 is collected through the waste liquid flow path 42 into the waste liquid container 50 by driving the pressure reducing unit 43 with the cap unit 41 separated from the liquid discharge head 22 by a predetermined gap distance. This suction is called idle suction. The idle suction is performed to discharge the liquid accumulated in the cap unit 41.

[0029] <Configuration of the nozzle surface of the liquid ejection unit 20> Next, the configuration of the nozzle surface of the liquid ejection unit 20 will be described with reference to FIG. 3, the liquid ejection section 20 is configured to be capable of recording by ejecting liquid from a plurality of nozzle groups N1 to N4 formed on a nozzle surface 28. In detail, a plurality of unit ejection heads 27 are arranged at regular intervals in the width direction X on the bottom of a liquid ejection head 22 provided in the liquid ejection section 20. The plurality of unit ejection heads 27 are arranged in an attitude inclined at a predetermined angle with respect to the transport direction Y in which the medium M is transported.

[0030] For example, one cap unit 41, indicated by a two-dot chain line in Fig. 3, faces every three unit discharge heads 27. As shown in Fig. 3, the cap unit 41 has a parallelogram opening shape in a plan view (i.e., in a bottom view), and is capable of capping three unit discharge heads 27 arranged at an angle with respect to the transport direction Y.

[0031] The unit discharge head 27 has a plurality of nozzle groups N1 to N4 (for example, four rows) each having a plurality of nozzles 21 arranged in rows that open to a nozzle surface 28. Each of the nozzle groups N1 to N4 has a predetermined number of nozzles 21 arranged in a row along the longitudinal direction of the unit discharge head 27. Although the nozzles 21 are omitted in Fig. 3, one nozzle group is formed by a row of a predetermined number (for example, about 400) of nozzles 21 in a range of 200 to 1000 nozzles (see Figs. 2 and 4).

[0032] The liquid ejection device 11 of this embodiment is capable of color printing. In an example where the liquid is ink, a first nozzle group N1, a second nozzle group N2, a third nozzle group N3, and a fourth nozzle group N4 are formed on the nozzle surface 28 of the liquid ejection head 22, each of which is made up of a row of nozzles 21 capable of ejecting four colors of ink. The first nozzle group N1 is formed by arranging the nozzles 21 ejecting black ink in a row at a constant nozzle pitch. The second nozzle group N2 is formed by arranging the nozzles 21 ejecting yellow ink in a row at a constant nozzle pitch. The third nozzle group N3 is formed by arranging the nozzles 21 ejecting cyan ink in a row at a constant nozzle pitch. The fourth nozzle group N4 is formed by arranging the nozzles 21 ejecting magenta ink in a row at a constant nozzle pitch. In the liquid ejection head 22, the unit ejection heads 27 are arranged at a predetermined inclination angle so that when the nozzles 21 are projected in the transport direction Y, the projected nozzles are aligned in the width direction X at a pitch according to the printing resolution over a range corresponding to the maximum width size of the medium M.

[0033] <Configuration of the maintenance unit 40> Next, referring to FIG. 4, the configuration of the maintenance unit 40 that maintains the nozzles 21 of the liquid ejection head 22 will be described. As shown in FIG. 4, the line printing type liquid ejection head 22 includes a plurality of unit ejection heads 27. The plurality of unit ejection heads 27 are held by a support unit 23. The plurality of unit ejection heads 27 are arranged side by side in the width direction X. In this embodiment, the number of unit ejection heads 27 is 36. Each unit ejection head 27 has a plurality of nozzles 21. Each unit ejection head 27 has a plurality of types of nozzles 21 that can eject a plurality of color liquids corresponding to the number of liquid containers 24. Each unit ejection head 27 is a unit that includes a plurality of types of nozzles 21 that can eject a plurality of color liquids. In this example, each unit ejection head 27 is a unit that includes four types of nozzles 21 that can eject four color liquids.

[0034] As shown in FIG. 4, the multiple unit discharge heads 27 are units in which one cap unit 41 covers multiple nozzles 21. That is, the multiple (N) nozzles 21 of the liquid discharge head 22 are covered by multiple (M) cap units 41 for each of the multiple unit discharge heads 27. In this example, the multiple (N) nozzles 21 of the liquid discharge head 22 are covered by 12 cap units 41 for each of three unit discharge heads 27. In this way, the multiple nozzles 21 of the liquid discharge head 22 are divided and covered by multiple cap units 41. The multiple nozzles 21 covered by one cap unit 41 correspond to an example of a "nozzle group". The liquid discharge head 22 has multiple (M) nozzle groups each composed of N / M nozzles 21. In this way, the liquid discharge head 22 has multiple (N) nozzles 21 composed of multiple (M) nozzle groups. Note that both N and M are natural numbers greater than or equal to 2, and have a relationship of N>M.

[0035] When the nozzles 21 of the multiple unit discharge heads 27 are projected in the transport direction of the medium M, the nozzles 21 of the projected unit discharge heads 27 are aligned at regular intervals in the width direction of the medium M for each color of liquid to be discharged. A detailed configuration of the liquid discharge head 22 will be described later.

[0036] The liquid ejection device 11 has a pressure pump 29 that pressurizes and supplies the liquid stored in the liquid container 24 toward the liquid ejection part 20. When the pressure pump 29 is driven, the liquid is supplied from the liquid container 24 through the supply flow path 25 to the liquid ejection part 20.

[0037] The maintenance unit 40 includes the above-mentioned cap unit 41 and suction mechanism 44, which are disposed at a position facing the nozzle surface 28 of the liquid ejection head 22. The suction mechanism 44 includes a waste liquid flow path 42 that connects the cap unit 41 and the waste liquid container 50, and a pressure reduction unit 43 provided midway along the waste liquid flow path 42. The pressure reduction unit 43 includes a buffer tank 52 capable of storing a fluid (mainly air) that has been reduced in pressure below atmospheric pressure, and a pressure reduction pump 43P that reduces the pressure of the buffer tank 52. The waste liquid flow path 42 includes a plurality of branch flow paths 53, one end of which is connected to each of the cap units 41, a junction flow path 54 that connects the other end of each branch flow path 53 to the buffer tank 52, and two flow paths 55 that connect the buffer tank 52 to the waste liquid container 50.

[0038] Hereinafter, the detailed configuration of the maintenance unit 40 will be described with reference to FIG. The cap unit 41 is in the shape of a bottomed box that opens upward, and is movable relative to the nozzle surface 28 of the liquid ejection head 22. The cap unit 41 moves from the retracted position toward the liquid ejection head 22 to a flushing position at a clearance distance from the nozzle surface 28, and to a capping position at which the nozzle surface 28 and the cap unit 41 form a closed space by contacting the nozzle surface 28. In this embodiment, the position of the cap unit 41 when the liquid ejection head 22 performs idle ejection is the flushing position. Also, the position at which the cap unit 41 contacts the nozzle surface 28 during cleaning or during standby without printing is the capping position. When the cap unit 41 is in the capping position, the nozzle 21 communicates with the closed space formed by the cap unit 41 and the nozzle surface 28, thereby suppressing thickening of the liquid in the nozzle 21.

[0039] As described above, one cap unit 41 is provided for each of the three unit ejection heads 27. One cap unit 41 is disposed at a position facing each of the three unit ejection heads 27. Each of the three unit ejection heads 27 is capped by a common cap unit 41. Furthermore, dummy ejection is performed for each of the three unit ejection heads 27, ejecting liquid toward the common cap unit 41. Furthermore, during standby when printing is performed and when the liquid ejection device 11 is turned off, the liquid ejection heads 22 are capped by a plurality of cap units 41. Note that the number of unit ejection heads 27 capped by a common cap unit 41 is not limited to three, and may be two or four or more. However, when the number of unit ejection heads 27 is N, it is preferable that the number of unit ejection heads 27 capped in common by one cap unit 41 is N / 3 or less.

[0040] The branch flow path 53 is provided with a first on-off valve 56 that allows or restricts the flow of fluid in the branch flow path 53. Therefore, when the cap unit 41 caps the liquid ejection head 22, if the first on-off valve 56 is opened, the inside of the cap unit 41 and the buffer tank 52 are brought into communication with each other via the branch flow path 53 and the junction flow path 54.

[0041] On the other hand, when the cap unit 41 caps the liquid ejection head 22, if the first on-off valve 56 is closed, the inside of the cap unit 41 and the buffer tank 52 are not in communication with each other. Also, each first on-off valve 56 can be opened and closed individually. Therefore, by opening only a specific first on-off valve 56, only the inside of the specific cap unit 41 corresponding to the first on-off valve 56 can be in communication with the buffer tank 52. Note that the other end of each branch flow path 53 may be connected to the buffer tank 52 without providing the junction flow path 54.

[0042] The buffer tank 52 is provided with a pressure sensor 57 for measuring the pressure inside the buffer tank 52 and an air release valve 58 for opening the buffer tank 52 to the atmosphere. When the air release valve 58 is open, the buffer tank 52 communicates with the atmosphere, and when it is closed, the buffer tank 52 does not communicate with the atmosphere. When the decompression pump 43P is driven with the first opening / closing valve 56 and the air release valve 58 closed, the buffer tank 52 is decompressed to a pressure (negative pressure) below atmospheric pressure. In addition, when the liquid ejection head 22 is capped and the buffer tank 52 is decompressed to a pressure below atmospheric pressure, by opening any of the first opening / closing valves 56, the negative pressure is quickly applied to any of the cap units 41 that communicate with the buffer tank 52. This shortens the operation time for suction cleaning and dry suction.

[0043] As shown in Fig. 4, two decompression pumps 43P are provided. The buffer tank 52 and the waste liquid container 50 are connected by two flow paths 55. The two decompression pumps 43P are provided midway through the two flow paths 55, respectively, and reduce the pressure in the buffer tank 52 via the flow paths 55. As an example, one of the two decompression pumps 43P may be a diaphragm pump and the other a rotary pump, so that the amount of pressure reduction by one decompression pump 43P is greater than the amount of pressure reduction by the other decompression pump 43P. Note that only one decompression pump 43P may be provided.

[0044] The maintenance unit 40 further includes a wiping unit 60 that performs a wiping process on the nozzle surface 28 of the liquid ejection head 22 , and a liquid discharge mechanism 61 that discharges the ink wiped by the wiping unit 60 into the waste liquid container 50 .

[0045] The wiping unit 60 has a wiper member 62 and a wiper carriage 63 that supports the wiper member 62. The wiping unit 60 wipes the nozzle surface 28 with the wiper member 62 by moving the wiper carriage 63 in the direction along the X-axis.

[0046] The liquid discharge mechanism 61 has a connection flow path 64 connectable to the wiper carriage 63, and an on-off valve 65 provided in the middle of the connection flow path 64. The downstream end of the connection flow path 64 is connected to the buffer tank 52. When the on-off valve 65 is opened, the liquid removed by the wiper member 62 is discharged into the buffer tank 52.

[0047] 4 includes a liquid ejection section 20 capable of ejecting liquid in an ejection direction D from nozzles 21 formed on a nozzle surface 28, a cap unit 41, and a suction mechanism 44 capable of sucking liquid through the cap unit 41. The suction mechanism 44 performs suction to create a negative pressure in the closed space during cleaning to suck and discharge liquid from the nozzles 21, and performs suction to discharge excess liquid accumulated in the cap unit 41.

[0048] At a predetermined time during printing or after wiping or cleaning, dummy discharge is performed in which droplets are discharged from the nozzles 21. By dummy discharge, droplets are accumulated little by little in the cap unit 41. In this way, liquid is supplied from the nozzles 21 into the cap unit 41 regularly or irregularly by cleaning or dummy discharge.

[0049] The cap unit 41 of the present embodiment stores a certain amount of liquid therein, and uses the stored liquid to keep the nozzles 21 moist during capping. The multiple cap units 41 are biased upward via springs (not shown) on the upper surface of a base member (not shown). The base member is movable between a maintenance position and a retracted position. When in the maintenance position, the base member may be provided so as to be movable to multiple height positions including a capping position, a flushing position, and the like. The multiple cap units 41 disposed in the capping position are in contact with the nozzle surface 28 while being pressed against it by the biasing force of the springs.

[0050] For this reason, a space S (see FIG. 6) in which the nozzle 21 opens is formed between the nozzle surface 28 and the cap unit 41. During cleaning, the air inside the cap unit 41 is sucked and discharged to the outside, thereby reducing the pressure in the space S and forcibly discharging the liquid from the nozzle 21. The liquid discharged from the nozzle 21 accumulates inside the cap unit 41, and any excess liquid exceeding a certain amount passes through the branch flow path 53 and is ultimately collected in the waste liquid container 50.

[0051] <Configuration of Cap Unit 41> Next, a detailed configuration of the cap unit 41 will be described with reference to Figures 5 to 8. As shown in Figures 5 and 6, the cap unit 41 is configured to be able to form a space S (see Figure 5) in which the nozzle 21 opens by coming into contact with the nozzle surface 28 of the liquid ejection section 20 capable of ejecting liquid from the nozzle 21 (see Figure 4) in the ejection direction D.

[0052] The cap unit 41 has a moisturizing function for moisturizing the liquid inside the nozzle 21 during capping. To this end, the cap unit 41 has a space forming part 71 that forms the space S, and a liquid storage part 72 that is provided below the space forming part 71 and is capable of storing the liquid.

[0053] The space forming part 71 of the cap unit 41 includes a lip part 73 which is a rectangular ring-shaped part formed along the entire circumference thereof, and an absorber 74 which is disposed in an area inside the lip part 73. The upper surface of the absorber 74 is located at a position lower than the height of the upper end of the lip part 73 in the discharge direction D. Therefore, in a capping state in which the lip part 73 of the space forming part 71 contacts the nozzle surface 28 of the liquid discharge part 20 shown by the two-dot chain line in FIG. 6, the upper surface of the absorber 74 is separated from the nozzle surface 28.

[0054] The space forming portion 71 has, for example, a rectangular box shape with an open upper side that can come into contact with the nozzle surface 28 of the liquid ejection head 22 so as to surround each nozzle 21. The space forming portion 71 has a rectangular frame-shaped lip portion 73 (seal portion) made of a flexible material such as rubber or elastomer around the entire upper end periphery of the opening. Note that in the cap unit 41 of this embodiment, the nozzle rows are arranged obliquely at a predetermined angle with respect to the width direction X, and therefore the cap unit 41 has a parallelogram shape when viewed in a plan view from the ejection direction D. Therefore, the lip portion 73 also has a parallelogram shape when viewed in a plan view from the ejection direction D.

[0055] As shown in FIG. 5, the cap unit 41 has an absorber 74 that is provided in the space forming portion 71 and can absorb liquid. The absorber 74 is formed of a porous material made of synthetic resin. The absorber 74 absorbs and holds liquid. The absorber 74 can hold a certain amount of liquid. The liquid held in the absorber 74 gradually becomes more concentrated in the moisturizer when capping is removed during printing or the like, or as the moisture evaporates during capping. The absorber 74 also has the function of suppressing the splashing of liquid discharged from the nozzle 21 during cleaning.

[0056] The absorbent 74 is disposed so as to be in contact with the partition wall 75 and the communicating passage 76. For this reason, liquid is likely to exist between the absorbent 74 and the bottom surface of the space forming portion 71 due to capillary action. In other words, liquid is likely to exist between the absorbent 74 and the partition wall 75 due to capillary action.

[0057] The space forming portion 71 has an upper housing 81. The upper housing 81 is a rectangular ring-shaped member. In this embodiment, the upper housing 81 is formed integrally with the lip portion 73. Therefore, the upper housing 81 is formed of the same material as that used for the lip portion 73. In other words, the upper housing 81 is made of a flexible member such as rubber or elastomer. Note that the upper housing 81 may be composed of multiple members including an upper end member including the lip portion 73 and a lower support member that supports the upper end member.

[0058] As shown in FIG. 6, the cap unit 41 includes a gas-permeable partition wall 75 that separates the space forming portion 71 and the liquid storage portion 72, and a communication passage 76 that communicates the space forming portion 71 and the liquid storage portion 72 separately from the partition wall 75. In detail, the upper housing 81 has a partition wall 83 that constitutes a part of the bottom wall of the space forming portion 71. The partition wall 83 is formed with a communication hole 83a that opens over a predetermined area including the center portion, and the above-mentioned communication passage 76. The partition wall 75 is fixed to the upper surface of the partition wall 83 in a state of covering the communication hole 83a from above. Therefore, the partition wall 75 has a ventilation area as large as the opening area of ​​the communication hole 83a. The ventilation area of ​​the partition wall 75 is larger than the opening area of ​​the communication passage 76. The partition wall 75 is formed of, for example, a moisture-permeable film. The moisture-permeable film that constitutes the partition wall 75 does not cover the communication passage 76. Furthermore, the partition wall 75 may be a gas-permeable material that allows water vapor to pass through, for example.

[0059] During idle ejection or cleaning, the liquid discharged from the nozzle 21 is discharged into the space forming portion 71 of the cap unit 41. The liquid discharged into the space forming portion 71 flows from the space forming portion 71 through the communication passage 76 to the liquid storage portion 72. Then, the liquid IL that flows into the liquid storage portion 72 is stored in the liquid storage portion 72. The gas evaporated from the liquid stored in the liquid storage portion 72 is supplied to the space forming portion 71 through the partition wall 75 having gas permeability.

[0060] The space forming portion 71 is exposed to the atmosphere and separated from the nozzle surface 28 during printing by the liquid ejection device 11. For this reason, moisture in the liquid within the space forming portion 71 easily evaporates. The liquid IL (e.g., ink) contains a humectant to suppress the drying or thickening of the liquid in the nozzle 21. The humectant has the function of suppressing the evaporation of moisture from the liquid IL. On the other hand, when the concentration of the humectant in the liquid IL becomes high to a certain extent, the humectant tries to absorb moisture. Therefore, when the liquid in the space forming portion 71 is not in a capping state, it is exposed to the atmosphere and the moisture evaporates. Then, when the concentration of the humectant in the liquid in the space forming portion 71 exceeds a certain level, the humectant absorbs moisture from the surrounding air. Therefore, when the cap unit 41 is in a capping state, the moisture (water vapor) in the space S is absorbed by the humectant, and the space S becomes easily dried. As a result, even when the capping state is in a capping state, moisture is easily evaporated from the liquid in the nozzle 21. In other words, the humectant in the liquid in the space forming portion 71 takes moisture from the liquid in the nozzle 21 through the space S. Therefore, the viscosity of the liquid in the nozzle 21 becomes easy to proceed.

[0061] The cap unit 41 of the present embodiment includes a liquid storage portion 72 capable of supplying moisture such as water vapor to the space S of the space forming portion 71 in order to suppress thickening of the liquid in this type of nozzle 21.

[0062] The liquid storage section 72 has a lower housing 82 in the shape of a square box with an open top. The lower housing 82 is made of, for example, synthetic resin. The lower housing 82 is joined to the underside of the upper housing 81. The upper housing 81 and the lower housing 82 may be joined by assembly, or by joining with an adhesive or welding, etc. The upper housing 81 and the lower housing 82 may be joined in a liquid-tight state. The upper housing 81 and the lower housing 82 may be constructed as a single unit.

[0063] The cap unit 41 has a first discharge port 77 that communicates between the inside of the liquid storage portion 72 and the outside. The liquid storage portion 72 has a discharge pipe portion 86 that extends from the inner bottom surface of the bottom wall 85 in the direction opposite to the discharge direction D (upward). The first discharge port 77 opens at the upper end surface of the discharge pipe portion 86.

[0064] 6 and 7, the first discharge port 77 opens in the liquid storage portion 72 at a position higher than the bottom wall 85 of the liquid storage portion 72. The volume of the liquid storage portion 72 is larger than the volume of the space forming portion 71. Moreover, the horizontal cross-sectional areas of the internal spaces of the liquid storage portion 72 and the space forming portion 71 are approximately the same. For this reason, the height of the first discharge port 77 from the bottom wall 85 of the liquid storage portion 72, that is, the extension length from the bottom wall 85, is larger than the height (length) from the partition wall 75 or the partition wall 83, which is the bottom surface of the space forming portion 71, to the tip (upper end) of the lip portion 73.

[0065] As shown in FIG. 6, the gap G (distance) between the partition 75 and the first outlet 77 is preferably as small as possible. The smaller the gap G, the larger the volume that can be stored in the liquid storage section 72 can be set, and the smaller the gap between the liquid level LP of the liquid in the liquid storage section 72 and the partition 75 can be. The larger the liquid storage volume of the liquid storage section 72, the more the rate at which the moisturizing agent concentration increases can be suppressed. In addition, the smaller the gap between the liquid level LP and the partition 75, that is, the smaller the volume ratio of air to the liquid in the liquid storage section 72, the faster the supply speed of moisture (water vapor) from the liquid storage section 72 to the space S via the partition 75 can be. The smaller the distance between the liquid IL in the liquid storage section 72 and the liquid in the space forming section 71, the faster the moisture transfer speed, so it is preferable to place the first outlet 77 as close to the partition 75 as possible.

[0066] As shown in Fig. 7, in this embodiment, two discharge pipe sections 86 are provided. Therefore, two first discharge ports 77 are provided. The discharge pipe section 86 has a connection pipe section 86a protruding from the bottom surface of the liquid storage section 72. One end (upstream end) of a tube constituting the branch flow path 53 (waste liquid flow path 42) is connected to the connection pipe section 86a. The discharge pipe section 86 is in communication with the waste liquid flow path 42 through an opening 86b. The number of first discharge ports 77 may be one or three or more.

[0067] 6 and 7, the communication passage 76 and the first discharge port 77 are provided at different positions when viewed in the discharge direction D. Therefore, the liquid discharged from the space S into the liquid storage portion 72 through the communication passage 76 during cleaning flows into a portion other than the first discharge port 77, and the liquid IL in the liquid storage portion 72 is agitated by a liquid flow generated by the liquid that has flowed in.

[0068] Fig. 8 shows the bottom surface of the space forming portion 71 with the absorber 74 removed. As shown in Fig. 8, the partition wall 75 (moisture permeable membrane) is provided across a predetermined region including the central portion of the space forming portion 71. Among the bottom surfaces of the space forming portion 71, the upper surface of the partition wall 83 has an area smaller than that of the partition wall 75. A plurality of (for example, two) communication passages 76 open into the upper surface of the partition wall 83 on the downstream side in the Y direction.

[0069] <Operation of the First Embodiment> Next, the operation of the liquid ejection device 11 in this embodiment will be described. In the liquid ejection device 11, the liquid ejection unit 20 prints on the medium M while the maintenance unit 40 is in the retracted position. When printing is completed, the maintenance unit 40 is placed in the maintenance position. As a result, the liquid ejection unit 20 is capped by the cap unit 41.

[0070] When it is time for flushing during printing, the maintenance unit 40 is placed in the maintenance position, and the liquid ejection unit 20 ejects droplets from the nozzles 21 to perform idling. When it is time for cleaning, the maintenance unit 40 is placed in the maintenance position, and the suction mechanism 44 is driven to perform cleaning. In this cleaning, the cap unit 41 comes into contact with the nozzle surface 28, and a space S is formed between the nozzle surface 28 and the space forming unit 71, where the nozzles 21 open. In this capping state, the suction mechanism 44 creates a negative pressure in the space S, and the liquid is forcibly sucked and discharged from the nozzles 21. The suction mechanism 44 sucks air in the space S through the first discharge port 77 in the cap unit 41, the partition wall 75 having gas permeability, and the communication passage 76. As a result, the space S becomes negative pressure. As a result, the liquid is forcibly sucked and discharged from the nozzles 21 into the space forming unit 71.

[0071] The liquid discharged into the space S in the space forming portion 71 flows through the communication passage 76 into the liquid storage portion 72. At this time, since the communication passage 76 is located at a different position from the first discharge port 77 as viewed from the discharge direction D, the liquid from the communication passage 76 flows into a portion of the liquid storage portion 72 other than the first discharge port 77. As a result, the liquid in the liquid storage portion 72 is agitated. If the first discharge port 77 is located directly below the communication passage 76, there is a risk that the fresh liquid (waste liquid) with a high moisture content from the communication passage 76 will be discharged directly into the first discharge port 77. In this case, the rate at which the concentration of the moisturizing agent in the liquid in the liquid storage portion 72 increases is likely to increase. When the concentration of the moisturizing agent in the liquid in the liquid storage portion 72 increases, the amount of moisture supplied from the liquid storage portion 72 to the space S and the supply rate of the moisture decrease. As a result, depending on the circumstances, the moisture in the space S may be taken away by the moisturizing agent in the liquid on the liquid storage portion 72 side.

[0072] In this embodiment, the liquid in the liquid storage portion 72 is agitated by flowing from the communication passage 76 into the liquid storage portion 72 other than the first outlet 77, and the agitated liquid is discharged from the first outlet 77. In other words, a mixture of old liquid and new liquid is discharged from the first outlet 77. As a result, the rate at which the concentration of the moisturizer in the liquid in the liquid storage portion 72 increases can be suppressed.

[0073] As a result of the liquid flowing into the liquid storage section 72, the amount of liquid in the liquid storage section 72 increases. The liquid that exceeds the height of the first discharge port 77 is discharged to the outside from the first discharge port 77. In other words, the liquid that exceeds the height of the first discharge port 77 is collected in the waste liquid storage body 50 from the first discharge port 77 through the discharge pipe section 86 and the waste liquid flow path 42. In this embodiment, the liquid discharged from the cap unit 41 is collected in the waste liquid storage body 50 through the buffer tank 52 by driving the decompression pump 43P.

[0074] Thereafter, the cap unit 41 moves away from the nozzle surface 28, and then the wiping unit 60 wipes the nozzle surface 28. Furthermore, after the liquid ejection unit 20 performs idle ejection, the liquid ejection unit 20 is capped by the cap unit 41.

[0075] During this capping, water vapor that has permeated through the partition 75 from the liquid storage section 72 is supplied to the space S. When the space is not capped, such as during printing or wiping, the space forming section 71 is exposed to the atmosphere. As a result, the moisture in the liquid held in the absorber 74 gradually evaporates, and the concentration of the moisturizer in the liquid gradually increases.

[0076] However, even if capping is performed in this state, moisture evaporated from the liquid in the liquid storage section 72 disposed below the space forming section 71 passes through the gas-permeable partition wall 75 and is supplied to the absorber 74 and space S. Therefore, the moisture in the space S approaches a saturated state due to the supply of moisture from the liquid storage section 72 and the absorber 74. As a result, moisture is less likely to be taken away from the liquid in the nozzle 21. In other words, the liquid in the nozzle 21 is kept moist.

[0077] <Advantages of the First Embodiment> (1-1) The cap unit 41 is configured to be able to form a space S in which the nozzle 21 opens by contacting the nozzle surface 28 of the liquid ejection section 20 capable of ejecting liquid in an ejection direction D from the nozzle 21 formed on the nozzle surface 28. The cap unit 41 has a space forming section 71, a liquid storage section 72, a partition wall 75, a communication passage 76, an absorber 74, and a first outlet 77. The space forming section 71 forms the space S. The liquid storage section 72 is provided below the space forming section 71 and is configured to be able to store liquid. The partition wall 75 is gas permeable and separates the space forming section 71 from the liquid storage section 72. The communication passage 76 communicates the space forming section 71 with the liquid storage section 72 separately from the partition wall 75. The absorber 74 is provided in the space forming section 71 and is configured to be able to absorb liquid. The first outlet 77 communicates the inside of the liquid storage section 72 with the outside. According to this configuration, since a large amount of liquid can be stored in the liquid storage portion 72, the concentration of the moisturizer in the cap unit 41 is unlikely to increase even if the moisture evaporates. This makes it possible to prevent a decrease in the moisturizing effect on the liquid in the nozzle 21 during capping due to a decrease in the moisture content of the liquid in the cap unit 41. For example, it is possible to prevent the liquid in the nozzle 21 from thickening.

[0078] (1-2) First outlet 77 opens into liquid storage portion 72 at a position higher than the bottom wall of liquid storage portion 72. This configuration allows liquid storage portion 72 to store a larger amount of liquid.

[0079] (1-3) The volume of liquid storage portion 72 is larger than the volume of space forming portion 71. According to this configuration, more liquid can be stored in liquid storage portion 72. (1-4) The communication passage 76 and the first discharge port 77 are provided at different positions when viewed in the discharge direction D. With this configuration, it is possible to prevent fresh liquid that has flowed from the space forming portion 71 to the liquid storage portion 72 from being discharged as is.

[0080] (1-5) The liquid ejection device 11 includes a liquid ejection section 20, a cap unit 41, and a suction mechanism 44. The liquid ejection section 20 is configured to be able to eject liquid in an ejection direction D from nozzles 21 formed in the nozzle surface 28. The suction mechanism 44 is configured to be able to suck in the liquid via a first outlet 77. With this liquid ejection device 11, the above-mentioned effects (1-1) to (1-4) obtained by the cap unit 41 can be obtained in the same way.

[0081] Second embodiment Next, a second embodiment will be described with reference to Figures 9 to 12. The second embodiment differs from the first embodiment in the configuration of the cap unit 41. The configuration of the liquid ejection device 11 other than the cap unit 41 is the same as that of the first embodiment.

[0082] As in the first embodiment, the liquid ejection device 11 comprises a liquid ejection section 20 capable of ejecting liquid in an ejection direction D from a nozzle 21 formed on a nozzle surface 28, a cap unit 41, and a suction mechanism 44 capable of sucking the liquid through a first outlet 77.

[0083] 9 to 11 has a common configuration with the first embodiment in the following respects. That is, the cap unit 41 includes a space forming portion 71 that forms a space S, and a liquid storage portion 72 that is provided below the space forming portion 71 and is capable of storing liquid. Furthermore, the cap unit 41 includes a partition wall 87 that separates the space forming portion 71 and the liquid storage portion 72, and a communication passage 88 that communicates between the space forming portion 71 and the liquid storage portion 72, separate from the partition wall 87. The partition wall 87 is gas permeable.

[0084] Furthermore, the cap unit 41 has absorbers 74, 78 that are provided in the space forming portion 71 and are capable of absorbing liquid, and a first outlet 77 that connects the inside of the liquid storage portion 72 to the outside. The space forming portion 71 has an upper housing 91 and a middle housing 92. The upper housing 91 is formed integrally with the lip portion 73. Therefore, the upper housing 91 is made of a flexible material such as rubber or elastomer.

[0085] The space forming portion 71 has a storage portion 97 that is recessed downward (in the discharge direction D) from the bottom surface of the space forming portion 71. For example, a ring-shaped storage portion 97 is recessed in the discharge direction D along the periphery of the bottom surface of the space forming portion 71. The storage portion 97 accommodates an absorber 78 that contacts the absorber 74. The absorber 74 is preferably disposed so as to contact the communication passage 88. The absorber 78 is preferably disposed so as to contact the partition wall 87. The absorber 74 is held in the space forming portion 71 with a plurality of pins 99 (shown in FIG. 10 ) that protrude upward from the partition wall 94 inserted therethrough.

[0086] More specifically, the middle housing 92 has a partition wall 94 that constitutes a part of the bottom wall of the space forming portion 71. The partition wall 94 has an upper wall portion 95 that supports the center of the absorber 74, and a recessed portion 96 that is bent from the peripheral portion of the upper wall portion 95 and recessed in the discharge direction D. A communication hole 96a is formed in the bottom of the recessed portion 96. The partition wall 87 is fixed to the inner bottom surface (upper surface) of the recessed portion 96 in a state where it covers the communication hole 96a from above. The partition wall 87 is made of, for example, a moisture permeable membrane. The partition wall 87 is formed of a moisture permeable membrane that covers the communication hole 96a. A portion of the bottom of the storage portion 97 that corresponds to the communication hole 96a is formed of a moisture permeable membrane. Note that no moisture permeable membrane is provided in the communication passage 88.

[0087] 11, partition wall 87 is provided on the bottom surface of storage portion 97. Here, the bottom surface of storage portion 97 refers to the inner bottom surface of recess 96. In other words, the bottom surface of storage portion 97 refers to the upper surface of the portion of recess 96 where communication hole 96a opens.

[0088] 10 and 11, the communication passage 88 is provided in the bottom surface of the space forming portion 71. Here, the bottom surface of the space forming portion 71 refers to the top surface of an upper wall portion 95, which is the portion of the partition wall 94 other than the recessed portion 96. The communication passage 88 opens into the upper wall portion 95, which is located higher than the recessed portion 96 of the partition wall 94.

[0089] 10, the liquid storage portion 72 has a curved guide surface 89 capable of guiding the liquid that has flowed in from the communication passage 88 in a direction different from the inflow direction. More specifically, the liquid storage portion 72 has a lower housing 93. The lower housing 93 has a side wall 84 and a bottom wall 85 that extend parallel to the discharge direction D. The portion of the liquid storage portion 72 that connects the side wall 84 and the bottom wall 85 is curved. The guide surface 89 is formed on the inner circumferential surface of the curved portion.

[0090] 10 and 11, the cap unit 41 has a first exhaust port 77 that communicates between the inside of the liquid storage portion 72 and the outside. The liquid storage portion 72 has a exhaust pipe portion 86 that extends from its bottom surface in a direction opposite to the discharge direction D (upward). The first exhaust port 77 opens into an upper end surface of the exhaust pipe portion 86. The first exhaust port 77 communicates between the inside of the liquid storage portion 72 and the outside.

[0091] 10 and 11, in liquid storage portion 72, first outlet 77 opens at a position higher than bottom wall 85 of liquid storage portion 72. The volume of liquid storage portion 72 is larger than the volume of space forming portion 71. The volume of liquid that can be stored in liquid storage portion 72 is larger than the volume of space forming portion 71. The volume of liquid that can be stored in liquid storage portion 72 is larger than the volume of storage portion 97.

[0092] 11, in the discharge direction D, the first discharge port 77 opens between the bottom surface of the space forming portion 71 and the partition wall 87. Here, the bottom surface of the space forming portion 71 refers to the top surface of the upper wall portion 95, which is the portion of the partition wall 94 other than the recessed portion 96. In other words, the bottom surface of the space forming portion 71 refers to the top surface of the upper wall portion 95, which is the portion of the partition wall 94 where the communication passage 88 opens.

[0093] The first discharge port 77 opens in the liquid storage portion 72 at a position higher than the bottom wall 85 of the liquid storage portion 72. The volume of the liquid storage portion 72 is larger than the volume of the space forming portion 71. Moreover, the horizontal cross-sectional areas of the internal spaces of the liquid storage portion 72 and the space forming portion 71 are approximately the same. For this reason, the height of the first discharge port 77 from the bottom wall 85 of the liquid storage portion 72, that is, the extension length from the bottom wall 85, is larger than the height (length) from the partition wall 87 or the partition wall 83, which is the bottom surface of the space forming portion 71, to the tip (upper end) of the lip portion 73.

[0094] As shown in Fig. 10, in this embodiment, two discharge pipe sections 86 are provided. Therefore, two first discharge ports 77 are provided. The discharge pipe section 86 has a connection pipe section 86a protruding from the bottom surface of the liquid storage section 72. One end (upstream end) of a tube constituting the branch flow path 53 (waste liquid flow path 42) is connected to the connection pipe section 86a. The discharge pipe section 86 is in communication with the waste liquid flow path 42 through an opening 86b. The number of first discharge ports 77 may be one or three or more.

[0095] 10, the communication passage 76 and the first discharge port 77 are provided at different positions when viewed in the discharge direction D. Therefore, the liquid discharged from the space S into the liquid storage portion 72 through the communication passage 88 during cleaning flows into a portion other than the first discharge port 77, and the liquid in the liquid storage portion 72 is agitated by a liquid flow generated by the liquid that has flowed in.

[0096] FIG. 12 shows the bottom surface of the space forming portion 71 with the absorbent 74 removed. As shown in FIG. 12, a storage portion 97 is formed along the periphery of the bottom surface of the space forming portion 71. Partition walls 87 (moisture permeable membranes) are provided at two locations on both sides of the storage portion 97 in the X direction on the bottom surface of the space forming portion 71. The two partition walls 87 extend along the Y direction. The upper surface of the upper wall portion 95 of the partition wall 94 is disposed in the center of the bottom surface of the space forming portion 71. The absorbent 74 (see FIG. 9) is mainly supported by the upper surface of the upper wall portion 95. One communication passage 88 opens in the center of the upper surface of the upper wall portion 95. Note that a plurality of communication passages 88 may be formed at positions different from the partition walls 87 on the bottom surface of the space forming portion 71.

[0097] As shown in FIGS. 10 and 11, the height of the first discharge port 77 determines the height of the liquid level LP of the liquid IL1 stored in the liquid storage section 72. Since the bottom surface of the storage section 97 is located lower than the first discharge port 77, the liquid IL2 is stored in the storage section 97 until the liquid level LP reaches the same height as the height of the first discharge port 77. The liquid IL2 in the storage section 97 is mainly the liquid discharged to the space S in the immediately preceding cleaning, and the moisturizer concentration thereof is relatively low immediately after cleaning. However, the moisturizer concentration thereof gradually increases as the liquid IL2 is exposed to the atmosphere during the subsequent printing. Therefore, in many cases, the moisturizer concentration of the liquid IL2 in the storage section 97 becomes higher than the moisturizer concentration of the liquid IL1 in the liquid storage section 72. When a difference in moisturizer concentration occurs between the liquids IL1 and IL2 on either side of the moisture-permeable membrane (partition 87) in this manner, the rate at which moisture moves from the liquid IL1 through the moisture-permeable membrane (partition 87) to the liquid IL2 increases in accordance with the difference in moisturizer concentration.

[0098] 13 is a graph showing the relationship between the moisture transfer rate and the moisturizer concentration difference in the liquids IL1 and IL2 on both sides of the partition 87. An example is shown in which the thickness of the moisture permeable membrane constituting the partition 87 is different. Examples of moisture permeable membranes having thicknesses of 600 μm, 300 μm, and 150 μm are shown by graph lines L1, L2, and L3, respectively. This graph also shows an example in which a space is provided between the moisture permeable membrane (partition 75) and the liquid level LP in the liquid storage section 72, as in the first embodiment, by graph line L0. As can be seen from the graph, the thinner the moisture permeable membrane, the faster the moisture transfer rate relative to the moisturizer concentration difference.

[0099] <Operation of the Second Embodiment> Next, the operation of the cap unit 41 in the second embodiment will be described. During cleaning, the liquid discharged from the nozzle 21 into the space S in the space forming part 71 is stored in the storage part 97 and flows through the communicating passage 88 to the liquid storage part 72. After cleaning, due to the hydraulic head pressure, the liquid level LP of the liquid IL1 in the liquid storage part 72 and the liquid level LP of the liquid IL2 in the storage part 97, which faces the liquid storage part 72 via the moisture permeable membrane (partition wall 87), become the same height.

[0100] At this time, because the communication passage 88 is in a different position from the first discharge port 77 when viewed from the discharge direction D, the liquid from the communication passage 88 flows into a portion of the liquid storage portion 72 other than the first discharge port 77. As a result, the liquid in the liquid storage portion 72 is agitated by the flow of the liquid that has flowed in. Furthermore, a liquid flow is generated that flows in a direction toward the center of the bottom wall 85 along the guide surface 89, which is a curved surface. This promotes the agitation of the liquid IL1 in the liquid storage portion 72.

[0101] Then, the liquid that exceeds the height of first outlet 77 is discharged to the outside from first outlet 77. In other words, liquid IL1 after being stirred is discharged from first outlet 77. For this reason, liquid IL1 that is a mixture of old liquid and new liquid is discharged from first outlet 77. As a result, the rate at which the moisturizer concentration in liquid IL1 in liquid storage section 72 increases can be slowed down.

[0102] The liquid discharged from the first discharge port 77 through the discharge pipe portion 86 and the waste liquid flow path 42 is collected in the waste liquid container 50. In this embodiment, the liquid discharged from the cap unit 41 is collected in the waste liquid container 50 through the buffer tank 52 by driving the decompression pump 43P.

[0103] Thereafter, the cap unit 41 moves away from the nozzle surface 28, and then the wiping unit 60 wipes the nozzle surface 28. Furthermore, after the liquid ejection unit 20 performs idle ejection, the liquid ejection unit 20 is capped by the cap unit 41.

[0104] During this capping, water vapor from the liquid IL1 in the liquid storage portion 72 passes through the partition wall 87 and is supplied to the storage portion 97. When the space forming portion 71 is uncapped, such as during printing or wiping, the space forming portion 71 is exposed to the atmosphere. As a result, the moisture in the liquid held in the absorbers 74, 78 and the liquid IL2 stored in the storage portion 97 gradually evaporates. As a result, the moisturizer concentrations in the liquid in the absorbers 74, 78 and the liquid IL2 in the storage portion 97 gradually increase.

[0105] In this state, the cap unit 41 comes into contact with the nozzle surface 28 to cap it. There is a difference in moisturizer concentration between the liquids IL1 and IL2 on both sides of the moisture-permeable membrane (partition 87) at the bottom of the storage section 97. That is, the moisturizer concentration of the liquid IL2 is usually higher than the moisturizer concentration of the liquid IL1. Therefore, due to the difference in moisturizer concentration, the water vapor of the liquid IL1 permeates the moisture-permeable membrane (partition 87) and moves into the storage section 97. As a result, the moisturizer concentration of the liquid IL2 in the storage section 97 decreases. Because the absorbers 74 and 78 are partially immersed in the liquid IL2, the moisturizer concentration of the liquid held in the absorbers 74 and 78 also decreases due to capillary action.

[0106] Therefore, the moisture necessary for the space S evaporates from the liquid held in the absorbers 74, 78 and the liquid IL2 in the storage portion 97, and the water vapor in the space S approaches a saturated state. As a result, moisture is less likely to be lost from the liquid in the nozzle 21. In other words, the liquid in the nozzle 21 is kept moist.

[0107] <Effects of the second embodiment> In the second embodiment, the partition wall 75 and the communicating passage 76 in the first embodiment are replaced by a partition wall 87 and a communicating passage 88. However, by having the same configuration as the first embodiment, the same effects as (1-1) to (1-5) in the first embodiment can be obtained, as well as the following effects.

[0108] (2-1) The space forming portion 71 has a storage portion that is recessed downward from the bottom surface of the space forming portion 71. The communication passage 88 is provided on the bottom surface of the space forming portion 71. The partition wall 87 is provided on the bottom surface of the storage portion. In the discharge direction D, the first discharge port 77 opens between the bottom surface of the space forming portion 71 and the partition wall 87. With this configuration, the liquid in the liquid storage portion 72 and the liquid absorbed in the absorbers 74, 78 can be brought into contact with each other via the partition wall 87, thereby improving the speed at which moisture moves to the liquid absorbed in the absorbers 74, 78.

[0109] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

[0110] 14 and 15, the cap unit 41 of the first and second embodiments may further include a second outlet 101 that opens into the bottom wall 85 of the liquid storage section 72 and communicates the inside of the liquid storage section 72 with the outside, an outlet flow path 103 that is connected to the second outlet 101, and an on-off valve 104 that can open and close the outlet flow path 103. A connection pipe section 102 that communicates with the second outlet 101 protrudes downward from the bottom wall 85. One end (upstream end) of the outlet flow path 103 is connected to the connection pipe section 102. The other end (downstream end) of the outlet flow path 103 is connected to, for example, the waste liquid flow path 42. FIG. 16 is a graph showing the timing for controlling the opening and closing of the on-off valve 104. In this graph, the horizontal axis shows the number of printed sheets, and the vertical axis shows the concentration of the moisturizer in the liquid storage section 72. Generally, during printing, the cap unit 41 is in an uncapping state and the liquid in the space forming portion 71 is exposed to the atmosphere, so that the humectant concentration increases as the number of printed sheets increases, as shown by the graph line F in FIG. 16. Each time the stored liquid replacement time Tx is reached, when the set number of printed sheets is reached and the humectant concentration is estimated to have reached a predetermined threshold, the liquid in the liquid storage portion 72 is replaced with new liquid. That is, when the stored liquid replacement time Tx is reached, the control unit 100 opens the opening / closing valve 104, which had been in a closed state until then, to drain the liquid in the liquid storage portion 72. When the drainage of the liquid in the liquid storage portion 72 is completed, the opening / closing valve 104 is closed. Next, the control unit 100 performs cleaning. As a result, new liquid is stored in the liquid storage portion 72. In this way, the control unit 100 replaces the liquid in the liquid storage portion 72 of the cap unit 41. According to this configuration, compared to the configuration of the above embodiment, it is possible to prevent the humectant concentration of the liquid in the liquid storage portion 72 from becoming excessively high. In each of the above embodiments, the rate at which the moisturizer concentration of the liquid in liquid storage portion 72 increases is suppressed by the stirring action, but even so, when an excessive number of sheets are printed, it is possible that the moisturizer concentration in the liquid in liquid storage portion 72 will exceed the allowable range. In this case, a service technician may need to perform maintenance by cleaning cap unit 41 and replacing the liquid in liquid storage portion 72, but this type of maintenance work can be omitted.

[0111] Thus, the liquid ejection device 11 includes the liquid ejection section 20, the cap unit 41, and the suction mechanism 44. The liquid ejection section 20 is configured to be capable of ejecting liquid in the ejection direction D from the nozzles 21 formed on the nozzle surface 28. The suction mechanism 44 is configured to be capable of sucking liquid via the first outlet 77 and the second outlet 101. With this configuration, the liquid ejection device 11, like the cap unit 41, can periodically discharge old liquid that has accumulated at the bottom of the liquid storage section 72.

[0112] In the configuration of the modified example shown in FIG. 14 and FIG. 15, the on-off valve 104 may be a manual on-off valve. In this case, the control unit 100 counts the number of printed sheets with an internal counter, and when the set number of printed sheets is reached, displays a message on the display unit constituting the operation unit 15 or the display unit of the host device, urging the user to replace the liquid in the liquid storage unit 72 of the cap unit 41. When the user operates the operation unit 15 for the OK operation, the control unit 100 displays an operation procedure, and the user operates according to the operation procedure. First, the user opens the on-off valve 104 and operates the operation unit 15. When a certain time has passed since the control unit 100 accepted the operation, the control unit 100 displays a message urging the user to close the on-off valve 104. When the user closes the on-off valve 104, the control unit 100 operates the operation unit 15. When the control unit 100 accepts the operation, it executes cleaning and causes the liquid storage unit 72 to store the required amount of liquid. With this configuration in which the user operates the on-off valve 104, the same effect as the configuration in which the control unit 100 controls the on-off valve 104 can be obtained. In this configuration, the opening and closing valve 104 may be operated by a serviceman instead of a user.

[0113] In the second embodiment, it is sufficient that the first discharge port 77 opens between the bottom surface of the space forming portion 71 and the partition wall 87 in the discharge direction D, and the first discharge port 77 may be located at the same height as the communicating passage 88. For example, the upper wall portion 95 constituting the partition wall 94 may have a convex portion that convex upward in a portion other than the communicating passage 88, and the first discharge port 77 may be located at the same height as the communicating passage 88 at a position corresponding to this convex portion.

[0114] In the first embodiment, the number of partition walls 75 is not limited to one, and may be multiple. For example, the number of partition walls 75 may be two or three or more. In the second embodiment, the number of partition walls 87 is not limited to two, and may be one or three or more.

[0115] In the second embodiment, the first exhaust port 77 and the partition wall 75 may be at the same height. In the first embodiment, the absorbent 74 does not have to be disposed so as to be in contact with the partition wall 75. Moreover, the absorbent 74 does not have to be disposed so as to be in contact with the communication passage 76. For example, a convex shape or a groove may be provided on the upper surface of the partition wall 83, and the absorbent 74 may be disposed so as to be in contact with the convex shape or the groove. These configurations allow smooth movement of moisture between the absorbent 74 and the communication passage 76, and smooth movement of moisture from the liquid storage section 72 to the absorbent 74 via the partition wall 75.

[0116] In the second embodiment, the absorber 74 does not have to be disposed so as to contact the partition wall 87. The absorber 74 does not have to be disposed so as to contact the communication passage 88. For example, a convex or a groove may be provided on the upper surface of the upper wall portion 95 constituting the partition wall 94, and the absorber 74 may be disposed so as to contact the convex or the groove. For example, a convex or a groove may be provided on the upper surface of the bottom of the recess 96 constituting the partition wall 94, and the absorber 78 may be disposed so as to contact the convex or the groove. These configurations allow smooth movement of moisture between the absorber 74 and the communication passage 88, and smooth movement of moisture from the liquid storage portion 72 to the absorber 78 via the partition wall 87.

[0117] The liquid ejection device 11 is not limited to a line printer, and may be a serial printer or a page printer. For example, in the case of a serial printer, the liquid ejection unit 20 is composed of a carriage that can move back and forth along the width direction X, and a liquid ejection head 22 provided on the carriage. Then, printing is performed on the medium M by alternately performing a transport operation that transports the medium M to the next printing position and a printing operation that ejects liquid droplets from the nozzles 21 of the liquid ejection head 22 during the movement of the carriage. Then, the maintenance unit 40 is disposed at a position facing the nozzle surface 28 of the liquid ejection head 22 when the carriage is at the home position. The cap unit 41 constituting the maintenance unit 40 is disposed in a state in which it can be raised and lowered at a position facing the nozzle surface of the liquid ejection head 22 when the carriage is at the home position. The cap unit 41 is raised by a lifting mechanism to come into contact with the nozzle surface 28 of the liquid ejection head 22. In this capping state, a space S in which the nozzle 21 is open is formed, surrounded by the space forming portion 71 and the nozzle surface 28 constituting the cap unit 41.

[0118] The liquid ejection device 11 is not limited to an inkjet printer that ejects liquid such as ink onto a medium M such as paper, but may be a textile printing device that ejects liquid such as ink onto fabric. The liquid ejection device 11 may not include the image reading unit 13 and may be a printer having only a printing function.

[0119] The technical ideas and effects derived from the above-described embodiment and modified examples will be described below. (A) The cap unit is a cap unit capable of forming a space in which the nozzle opens by contacting the nozzle surface of a liquid ejection section capable of ejecting liquid in an ejection direction from a nozzle formed on the nozzle surface, and has a space forming section that forms the space, a liquid storage section that is provided below the space forming section and is capable of storing liquid, a partition wall that is gas permeable and separates the space forming section from the liquid storage section, a communicating passage that connects the space forming section and the liquid storage section separately from the partition wall, an absorbent that is provided in the space forming section and is capable of absorbing liquid, and a first exhaust port that connects the inside of the liquid storage section to the outside.

[0120] According to this configuration, since a large amount of liquid can be stored in the liquid storage section, the concentration of the moisturizer in the cap unit is unlikely to increase even if the moisture evaporates. Therefore, it is possible to prevent a decrease in the moisturizing effect on the liquid in the nozzle during capping due to a decrease in moisture from the liquid in the cap unit. As a result, for example, thickening of the liquid in the nozzle can be prevented.

[0121] (B) In the cap unit described above in (A), the first outlet may open into the liquid storage section at a position higher than a bottom wall of the liquid storage section. With this configuration, a larger amount of liquid can be stored in the liquid storage section.

[0122] (C) In the cap unit described above in (A) or (B), the volume of the liquid storage portion may be larger than the volume of the space forming portion. With this configuration, a larger amount of liquid can be stored in the liquid storage portion.

[0123] (D) In ​​the cap unit according to any one of (A) to (C) above, the communication passage and the first discharge port may be provided at different positions when viewed in the discharge direction. With this configuration, it is possible to prevent fresh liquid that has flowed from the space forming portion to the liquid storage portion from being discharged as is.

[0124] (E) In the cap unit described in any one of (A) to (D) above, the space forming portion may have a storage portion that is recessed downward from a bottom surface of the space forming portion, the communication passage may be provided on the bottom surface of the space forming portion, the partition wall may be provided on the bottom surface of the storage portion, and the first discharge port may open between the bottom surface of the space forming portion and the partition wall in the discharge direction. With this configuration, the liquid in the liquid storage portion and the liquid absorbed in the absorber can be brought into contact with each other via the partition wall, thereby improving the speed of moisture transfer to the liquid absorbed in the absorber.

[0125] (F) In the cap unit described in any one of (A) to (E) above, the liquid storage portion may have a curved guide surface capable of guiding the liquid that has flowed in from the communication passage in a direction different from the direction in which the liquid flows in. With this configuration, the liquid is easily agitated in the liquid storage portion, making it possible to prevent old liquid from remaining in the liquid storage portion.

[0126] (G) The cap unit according to any one of (A) to (F) above may further include a second outlet opening in a bottom wall of the liquid storage portion and communicating the inside of the liquid storage portion with the outside, a discharge flow path connected to the second outlet, and an on-off valve capable of opening and closing the discharge flow path. With this configuration, old liquid accumulated at the bottom of the liquid storage portion can be periodically discharged.

[0127] (H) A liquid ejection device includes a liquid ejection section capable of ejecting liquid in an ejection direction from nozzles formed on a nozzle face, a cap unit according to any one of (A) to (F) above, and a suction mechanism capable of sucking the liquid through the first outlet. With this configuration, the liquid ejection device can achieve the same effects as those of (A) to (F) above.

[0128] (I) A liquid ejection device includes a liquid ejection section capable of ejecting liquid in an ejection direction from nozzles formed on a nozzle face, the cap unit described in (G) above, and a suction mechanism capable of sucking the liquid through the first outlet and the second outlet. With this configuration, the liquid ejection device can achieve the same effect as (G) above. [Explanation of symbols]

[0129] 11...liquid ejection device, 12...device body, 13...image reading device, 14...automatic feed device, 15...operation unit, 16...medium storage unit, 16A...edge guide, 17...stacker, 18...casing, 19...size detection unit, 20...liquid ejection unit, 21...nozzle, 22...liquid ejection head, 23...support unit, 24...liquid storage body, 25...supply flow path, 25S...liquid supply mechanism, 26...holder, 27...unit ejection head, 28...nozzle surface, 29...check valve, 30...transport unit, 3 1...feed roller, 33...transport roller, 34...transport belt, 37...support part moving mechanism, 40...maintenance part, 41...cap unit, 42...waste liquid flow path, 43...pressure reduction unit, 43P...pressure reduction pump, 44...suction mechanism, 45...cap moving mechanism, 50...waste liquid container, 51...holder, 52...buffer tank, 55...flow path, 56...first opening / closing valve, 57...pressure sensor, 58...atmospheric release valve, 60...wiping part, 61...liquid discharge mechanism, 62...wipe Par member, 63...wiper carriage, 64...connecting flow path, 65...opening / closing valve, 71...space forming portion, 72...liquid storage portion, 73...lip portion, 74...absorber, 75...partition wall, 76...communicating passage, 77...first discharge port, 78...absorber, 81...upper housing, 82...lower housing, 83...partition wall, 83a...communicating hole, 84...side wall, 85...bottom wall, 86a...connecting pipe portion, 86b...opening, 87...partition wall, 88...communicating passage, 89...guide surface, 91...upper housing, 92... Middle housing, 93...lower housing, 94...partition wall, 95...upper wall portion, 96...recess, 97...storage portion, 99...pin, 100...control portion, 101...second discharge port, 102..., 103...discharge flow path, 104...opening / closing valve, N1...first nozzle group, N2...second nozzle group, N3...third nozzle group, N4...fourth nozzle group, S...space, G...spacing, X...width direction, Y...conveying direction, Z...vertical direction, IL...liquid, IL1...liquid, IL2...liquid, LP...liquid level, D...discharge direction.

Claims

1. a cap unit capable of forming a space in which a nozzle is open by contacting a nozzle surface of a liquid ejection section capable of ejecting liquid in an ejection direction from a nozzle formed on the nozzle surface, A space forming portion that forms the space; a liquid storage portion provided below the space forming portion and capable of storing liquid; a partition wall having gas permeability and partitioning the space forming portion and the liquid storage portion; a communication passage that communicates the space forming portion and the liquid storage portion separately from the partition wall; an absorbent body provided in the space forming portion and capable of absorbing liquid; A first outlet that communicates the inside of the liquid storage portion with the outside; A cap unit comprising:

2. The cap unit according to claim 1 , wherein the first outlet is open in the liquid storage portion at a position higher than a bottom wall of the liquid storage portion.

3. 2. The cap unit according to claim 1, wherein the liquid storage portion has a volume larger than the volume of the space forming portion.

4. The cap unit according to claim 1 , wherein the communication passage and the first discharge port are provided at different positions when viewed in the discharge direction.

5. The space forming portion has a storage portion that is recessed downward from a bottom surface of the space forming portion, The communication passage is provided on the bottom surface of the space forming portion, The partition is provided on a bottom surface of the storage portion, The cap unit according to claim 1 , wherein the first discharge port opens between the bottom surface of the space forming portion and the partition wall in the discharge direction.

6. 2. The cap unit according to claim 1, wherein the liquid storage portion has a curved guide surface capable of guiding the liquid flowing in from the communication passage in a direction different from the flow-in direction.

7. a second outlet opening in a bottom wall of the liquid storage portion and communicating the inside of the liquid storage portion with the outside; A discharge flow path connected to the second discharge port; an on-off valve capable of opening and closing the discharge flow path; The cap unit according to claim 1 , further comprising:

8. a liquid ejection unit capable of ejecting liquid in an ejection direction from a nozzle formed on a nozzle surface; A cap unit according to any one of claims 1 to 6; a suction mechanism capable of sucking the liquid through the first outlet; A liquid ejection device comprising:

9. a liquid ejection unit capable of ejecting liquid in an ejection direction from a nozzle formed on a nozzle surface; A cap unit according to claim 7; a suction mechanism capable of sucking the liquid through the first outlet and the second outlet; A liquid ejection device comprising:

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