Inkjet recording device

Abstract

This invention provides an inkjet recording device with a compact and low-cost configuration that can prevent nozzle clogging and suppress nozzle drying, all within a single cap section. [Solution] The inkjet recording device 1 comprises a recording head 52, a cap section 13C, an ink discharge section 14, and a humidification section 15. The cap section 13C comprises a partition wall 22, an ink absorber 21, and a humidification fluid flowing body 23. The partition wall 22 divides the inside of the cap section 13C into a first space Sp1 through which ink and humidification fluid flow, and a second space Sp2 through which only humidification fluid flows. The ink absorber 21 is made of a first porous material through which ink can pass. The partition wall 22 is made of a second porous material having an average pore diameter smaller than that of the first porous material, through which only gas can pass. The humidification fluid flowing body 23 is made of a third porous material having an average pore diameter greater than or equal to that of the first porous material.

Description

Technical Field

[0001] The present invention relates to an inkjet recording apparatus.

Background Art

[0002] As a recording apparatus such as a printer or a copier, an inkjet recording apparatus that ejects ink onto a recording medium such as paper to record an image is widely used because it can record a high-definition image. In such an inkjet recording apparatus, the ink in the nozzles provided on the ink ejection surface of the recording head may thicken due to drying or the like, resulting in ejection failure. In order to suppress the thickening of the ink in the nozzles, conventional techniques such as capping, purging (forced ejection), and humidification inside the cap are known for the recording head and nozzles.

[0003] For example, the cap device of a conventional liquid ejection apparatus disclosed in Patent Document 1 can form a space surrounding the opening of the nozzle of the liquid ejection head. Inside the recess that forms the space, there are provided a humidification chamber into which a humidification fluid for humidifying the space flows in and out, and a gas-permeable partition wall that partitions the recess and the humidification chamber. Thereby, both prevention of nozzle clogging and suppression of nozzle drying can be achieved with a single cap, and an increase in the size of the apparatus can be suppressed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in conventional technology, because the head unit and cap device are inclined with respect to the horizontal direction, the humidifying fluid does not easily accumulate in the upper part of the inclined direction within the cap, making it difficult to humidify uniformly across the entire nozzle surface.

[0006] The present invention has been made in view of the above points, and aims to provide an inkjet recording device that can uniformly humidify the entire surface of the ink ejection area, thereby preventing nozzle clogging and suppressing nozzle drying, all with a single cap. [Means for solving the problem]

[0007] To solve the above problems, the inkjet recording apparatus of the present invention comprises a recording head, a cap portion, an ink discharge portion, and a humidifying portion. The recording head has an ink discharge surface through which nozzles for discharging ink onto a recording medium open. The cap portion is detachably attached to the ink discharge surface and covers the ink discharge surface. The ink discharge portion is connected to the cap portion and discharges the ink from the nozzles via the cap portion, discharging the ink inside the cap portion to the outside. The humidifying portion supplies a humidifying fluid containing humidifying liquid and gas into the cap portion attached to the ink discharge surface. The cap portion comprises a partition body, an ink absorber, and a humidifying fluid flowing body. The partition body is arranged inside the cap portion and divides the inside of the cap portion into a first space through which the ink and the humidifying fluid flow, and a second space through which only the humidifying fluid flow. The ink absorber is arranged in the first space and absorbs the ink. The humidifying fluid flowing body is arranged in the second space through which the humidifying fluid flows. The ink absorber is made of a first porous material through which the ink can pass. The partition is made of a second porous material having a smaller average pore diameter than the first porous material, through which only the gas can pass. The humidifying fluid flowing body is made of a third porous material having an average pore diameter greater than or equal to that of the first porous material. [Effects of the Invention]

[0008] According to the configuration of the present invention, a humidifying fluid circulating body made of a third porous material is arranged in a second space within the cap through which the humidifying fluid flows. Therefore, the capillary force of the humidifying fluid circulating body makes it possible to uniformly distribute the humidifying fluid throughout the entire circulating body. In other words, even when the ink ejection surface is inclined with respect to the horizontal direction, the entire surface of the ink ejection surface can be uniformly humidified. This makes it possible to prevent nozzle clogging and suppress nozzle drying with a single cap. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional front view of an inkjet recording apparatus according to the first embodiment of the present invention. [Figure 2] Figure 1 is a plan view of the area around the recording section of an inkjet recording device. [Figure 3] Figure 2 is a side view of the recording head. [Figure 4] Figure 2 is a bottom view of the recording head. [Figure 5] Figure 1 is a perspective view of the recording unit and maintenance unit of the inkjet recording device. [Figure 6] Figure 5 is a perspective view of the cap unit of the maintenance unit. [Figure 7] Figure 5 is an explanatory diagram showing the configuration of the recording head and cap unit, as well as the ink discharge unit and humidification unit. [Figure 8] Figure 7 is a top view of the cap portion. [Figure 9] Figure 7 is an explanatory diagram showing the flow of ink inside the cap. [Figure 10] Figure 7 is an explanatory diagram showing the flow of the humidifying fluid inside the cap. [Figure 11] Figure 7 is an explanatory diagram showing the gas flow of the humidifying fluid inside the cap section. [Figure 12] This is a cross-sectional front view of the recording head and cap portion of the inkjet recording device of Modified Example 1. [Figure 13]It is a top view of the cap portion of FIG. 12. [Figure 14] It is an exploded perspective view of the ink absorber, the partition body, and the humidifying fluid flow body of FIG. 12. [Figure 15] It is a cross-sectional front view of the recording head and the cap portion of the inkjet recording apparatus of Modification 2.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described based on the drawings. Note that the present invention is not limited to the following content.

[0011] FIG. 1 is a schematic cross-sectional front view of the inkjet recording apparatus 1 of the embodiment. FIG. 2 is a plan view of the periphery of the recording unit 5 of the inkjet recording apparatus 1 of FIG. 1. The inkjet recording apparatus 1 is, for example, an inkjet recording type printer. As shown in FIGS. 1, 2, and 3, the inkjet recording apparatus 1 includes an apparatus main body 2, a sheet supply unit 3, a sheet conveyance unit 4, a recording unit 5, a drying unit 6, and a control unit 7.

[0012] The sheet supply unit 3 is disposed, for example, at the lower part of the apparatus main body 2. The sheet supply unit 3 accommodates a plurality of sheets (recording media) S and separates and feeds out the sheets S one by one at the time of recording.

[0013] The sheet conveyance unit 4 is disposed on the downstream side in the sheet conveyance direction of the sheet supply unit 3 and above. The sheet conveyance unit 4 conveys the sheet S fed out from the sheet supply unit 3. The sheet conveyance unit 4 conveys the sheet S to the recording unit 5 and the drying unit 6, and further discharges the sheet S after recording and drying to the sheet discharge unit 2d. In addition, the sheet conveyance unit 4 has, for example, a reverse conveyance unit 4r. When double-sided recording is performed, the sheet conveyance unit 4 distributes the sheet S after recording and drying on the first side to the reverse conveyance unit 4r, and further conveys the sheet S with the conveyance direction switched and the front and back reversed to the recording unit 5 and the drying unit 6 again.

[0014] The sheet conveyance unit 4 includes a first belt conveyance unit 41 and a second belt conveyance unit 42. The first belt conveyance unit 41 has an endless first conveyance belt 411. The second belt conveyance unit 42 has an endless second conveyance belt 421. The first belt conveyance unit 41 and the second belt conveyance unit 42 adsorb and hold the sheet S on the upper outer surface (upper surface) of each of the first conveyance belt 411 and the second conveyance belt 421 and convey it. The first belt conveyance unit 41 is disposed below the recording unit 5 and conveys the sheet S. The second belt conveyance unit 42 is located on the downstream side in the sheet conveyance direction with respect to the first belt conveyance unit 41, is disposed in the drying unit 6, and conveys the sheet S.

[0015] The recording unit 5 is located on the downstream side in the sheet conveyance direction of the sheet supply unit 3 and is disposed opposite to the first belt conveyance unit 41. The recording unit 5 faces the sheet S adsorbed and held on the upper surface of the first conveyance belt 411 and is disposed above the first conveyance belt 411 with a predetermined interval. That is, the recording unit 5 faces the sheet S conveyed by the sheet conveyance unit 4.

[0016] As shown in FIG. 2, the recording unit 5 holds head units 51B, 51C, 51M, and 51Y corresponding to each of the four colors of black, cyan, magenta, and yellow. The head units 51B, 51C, 51M, and 51Y are juxtaposed along the sheet conveyance direction Dc so that the longitudinal direction is parallel to the sheet width direction Dw orthogonal to the sheet conveyance direction Dc. Since the basic configurations of the four head units 51B, 51C, 51M, and 51Y are the same, in the following description, the identification symbols "B", "C", "M", and "Y" representing each color may be omitted unless otherwise limited.

[0017] Each head unit 51 of each color has a line type inkjet recording head 52. In each head unit 51 of each color, a plurality (for example, three (52a, 52b, 52c)) are arranged in a staggered manner along the sheet width direction Dw.

[0018] The recording head 52 has a plurality of nozzles 521 at its bottom. The plurality of nozzles 521 are arranged in a line along the sheet width direction Dw, and are able to eject ink over the entire recording area on the sheet S. In other words, the recording head 52 has a plurality of nozzles 521 that eject ink onto the sheet S. The recording unit 5 sequentially ejects ink from each of the four color head units 51B, 51C, 51M, and 51Y recording heads 52 toward the sheet S which is being transported by the first transport belt 411, and records a full-color image or a monochrome image on the sheet S.

[0019] The drying unit 6 is located downstream of the recording unit 5 in the sheet transport direction and is positioned laterally. The drying unit 6 is provided with a second belt transport unit 42. The sheet S on which the ink image has been recorded in the recording unit 5 is held by the second transport belt 421 in the drying unit 6 and transported while the ink dries. The sheet S on which the image has been recorded, dried, and printing is complete is discharged to the sheet discharge unit 2d provided on the upper side of the main body 2 of the device.

[0020] The control unit 7 includes a CPU, an image processing unit, a memory unit, and other electronic circuits and electronic components (none of which are shown). The CPU controls the operation of each component provided in the inkjet recording device 1 based on control programs and data stored in the memory unit, and performs processing related to the functions of the inkjet recording device 1. The sheet supply unit 3, sheet transport unit 4, recording unit 5, and drying unit 6 each receive individual commands from the control unit 7 and perform recording on the sheet S in conjunction with each other. The memory unit is composed of a combination of non-volatile storage devices such as program ROM (Read Only Memory) and data ROM, and volatile storage devices such as RAM (Random Access Memory).

[0021] Next, the configuration of the recording head 52 of the recording unit 5 will be explained using Figures 3 and 4. Figures 3 and 4 are side and bottom views of the recording head 52 shown in Figure 2. Note that the three recording heads 52a, 52b, and 52c of each color have the same shape and configuration, so the identification symbols (a, b, c) will be omitted in the following explanation.

[0022] The recording head 52 has an ink ejection surface 52F on its lower surface. The ink ejection surface 52F faces the surface (upper surface) of the sheet S being transported on the first conveyor belt 411. As shown in Figure 3, the ink ejection surface 52F has a nozzle area 52R in which a number of nozzles 521 are arranged. That is, the ink ejection surface 52F has a number of nozzles 521 that open and eject ink onto the sheet S. A water-repellent film (not shown) is formed on the ink ejection surface 52F. Each of the four color (black, cyan, magenta, yellow) recording heads 52 is individually supplied with four colors of ink stored in an ink tank outside the head unit 51.

[0023] Based on a control signal from the control unit 7, the recording head 52 ejects ink from the nozzle 521 toward the sheet S that is being transported by being held and adsorbed onto the transport surface of the first transport belt 411, according to the image data received from the external computer. More specifically, the control unit 7 inputs an ejection drive signal with a predetermined drive voltage and pulse width to the recording head 52 to drive the recording head 52 and eject ink from the nozzle 521. As a result, a color image or a monochrome image is formed on the sheet S on the first transport belt 411 by superimposing four colors of ink: black, cyan, magenta, and yellow.

[0024] Furthermore, as shown in Figure 1, the inkjet recording device 1 includes a maintenance unit 11 and a unit movement mechanism 12. The maintenance unit 11 is detachable from the ink ejection surface 52F of the recording head 52 by the unit movement mechanism 12. When maintenance processing of the recording head 52 is not performed, the control unit 7 uses the unit movement mechanism 12 to position the maintenance unit 11 in a first position below the second belt transport unit 42, retracted from below the recording unit 5 as shown in Figure 1.

[0025] In the inkjet recording device 1, maintenance processing for the recording head 52 is performed at predetermined timings. This maintenance processing for the recording head 52 is performed, for example, when recording starts after a long period of inactivity or in between recording operations, in order to suppress drying of the ink ejection surface 52F and nozzles 521 of the recording head 52, and to remove thickened ink, solidified ink, foreign matter, etc. When performing maintenance processing for the recording head 52, the control unit 7 moves the maintenance unit 11 to a second position below the recording unit 5 using the unit moving mechanism 12.

[0026] During maintenance of the recording head 52, the first belt transport unit 41, which is positioned opposite the lower surface of the recording unit 5, is retracted by a movement mechanism (not shown) of the transport unit to a position lower than that shown in Figure 1, closer to the sheet supply unit 3. Subsequently, the maintenance unit 11 is moved to a second position below the recording unit 5, bringing it closer to the ink ejection surface 52F.

[0027] Figure 5 is a perspective view of the recording unit 5 and maintenance unit 11 of the inkjet recording device 1 shown in Figure 1. Figure 6 is a perspective view of the cap unit 13 of the maintenance unit 11 shown in Figure 5.

[0028] The maintenance unit 11 includes a cap unit 13. During maintenance of the recording head 52, the cap unit 13 is positioned to cover the ink ejection surface 52F and is mounted on the lower surface of the recording unit 5. The cap unit 13 has a tray 13T and a cap portion 13C. The tray 13T is formed in a rectangular shape that extends horizontally in the sheet transport direction Dc and the sheet width direction Dw.

[0029] The cap portion 13C is positioned on the upper surface of the tray 13T. The cap portion 13C is positioned to correspond to a plurality of recording heads 52a, 52b, 52c which are arranged in a staggered pattern along the sheet width direction Dw for each color. In other words, in this embodiment, the cap unit 13 has 12 cap portions 13C. The cap portion 13C is made of an elastic material such as rubber and is formed in a concave shape that is recessed downwards.

[0030] The cap portion 13C is detachable from the ink ejection surface 52F and covers the ink ejection surface 52F. The cap portion 13C is formed in a rectangular, oval, or other shape, extending horizontally in the sheet transport direction Dc and the sheet width direction Dw. Similar to the ink ejection surface 52F, the cap portion 13C is longitudinal, extending longer in the sheet width direction Dw than in the sheet transport direction Dc. When the cap unit 13 is positioned to cover the ink ejection surface 52F, the bottom of the recording head 52 enters the inside of the cap portion 13C, forming a closed space between the ink ejection surface 52F and the cap portion 13C.

[0031] The unit movement mechanism 12 is located below the recording unit 5 and the drying unit 6. The unit movement mechanism 12 includes a carriage 121, a horizontal movement mechanism 122, and a lifting mechanism 123, and also supports the maintenance unit 11.

[0032] The carriage 121 is supported by the horizontal movement mechanism 122. The carriage 121 is formed in the shape of a rectangular box with an open top and houses the maintenance unit 11 inside. The carriage 121 also holds the lifting mechanism 123.

[0033] The horizontal movement mechanism 122 includes a guide rail 1221 and a motor 1222.

[0034] Guide rails 1221 are positioned at one end and the other end of the sheet width direction Dw, and extend horizontally along the sheet transport direction Dc from below the recording unit 5 to below the drying unit 6. The maintenance unit 11 is supported by the guide rails 1221 so as to be able to move horizontally along them. The cap unit 13 is supported independently above the carriage 121.

[0035] The motor 1222 is positioned adjacent to the guide rail 1221, and its output shaft is connected to the cap unit 13 and carriage 121 via a gear group or wires and pulleys (not shown). When the motor 1222 is driven, the horizontal movement mechanism 122 moves the cap unit 13 and carriage 121 horizontally along the sheet transport direction Dc. The horizontal movement mechanism 122 can move the cap unit 13 and carriage 121 horizontally individually.

[0036] The lifting mechanism 123 includes a support mechanism (not shown) and a motor 1231. The support mechanism is located at the bottom of the carriage 121. The support mechanism supports the bottom of the maintenance unit 11 and is connected to the motor 1231 via a gear group, or wires and pulleys (neither shown), etc.

[0037] When the motor 1231 is started, the lifting mechanism 123 drives the support mechanism to push up or pull down the maintenance unit 11, thereby raising or lowering the maintenance unit 11. In other words, the cap unit 13 is raised or lowered by the lifting mechanism 123.

[0038] Furthermore, the maintenance unit 11 includes an ink discharge unit 14 and a humidification unit 15. Figure 7 is an explanatory diagram showing the configuration of the recording head 52 and cap unit 13 of Figure 5, and the ink discharge unit 14 and humidification unit 15. Figure 8 is a top view of the cap unit 13C of Figure 7.

[0039] The ink discharge unit 14 is connected to the cap unit 13C. The ink discharge unit 14 discharges ink from the nozzle 521 via the cap unit 13C and discharges the ink inside the cap unit 13C to the outside. The ink discharge unit 14 includes a discharge pipe 141, a discharge pump 142, and a waste liquid tank 143.

[0040] In this embodiment, two discharge pipes 141 are provided, with one end of each connected to the cap portion 13C and the other end connected to the waste liquid tank 143. The two discharge pipes 141 are connected, for example, to both ends of the cap portion 13C in the sheet width direction Dw. More specifically, the two discharge pipes 141 are individually connected to outlets 13Ca and 13Cb provided on the lower surface of both ends of the cap portion 13C in the sheet width direction Dw. The ink inside the cap portion 13C flows into each of the two discharge pipes 141 via the outlets 13Ca and 13Cb, is discharged to the outside of the cap portion 13C, and is sent to the waste liquid tank 143.

[0041] The discharge pump 142 is located downstream of the discharge port 13Ca of one of the discharge pipes 141 in the ink discharge direction, and is positioned in the middle of the discharge pipe 141 that extends to the waste liquid tank 143. The discharge pump 142 applies negative pressure to the cap portion 13C attached to the ink discharge surface 52F, and sucks the ink from inside the cap portion 13C. This makes it possible to forcibly discharge the ink from inside the nozzle 521. In other words, it is possible to prevent clogging of the nozzle 521. The discharge pump 142 sucks the ink from inside the cap portion 13C and discharges the ink towards the waste liquid tank 143. The operation of the discharge pump 142 is controlled by the control unit 7.

[0042] The waste liquid tank 143 is connected to the cap section 13C via the discharge pipe 141. The waste liquid tank 143 contains the ink (waste liquid) that is discharged from the nozzle 521 via the cap section 13C and discharged to the outside of the cap section 13C.

[0043] The humidifying unit 15 is connected to the cap portion 13C. The humidifying unit 15 supplies humidifying fluid into the cap portion 13C, which is attached to the ink ejection surface 52F. The humidifying unit 15 comprises a humidifying fluid tank 151, a supply pipe 152, a supply pump 153, and a recovery pipe 154.

[0044] The humidifying fluid tank 151 is connected to the cap section 13C via a supply pipe 152. The humidifying fluid tank 151 contains the humidifying fluid supplied to the cap section 13C. The humidifying fluid includes both a humidifying liquid and a gas.

[0045] The humidifying fluid is supplied into the cap portion 13C to humidify the ink absorbed by the ink ejection surface 52F of the recording head 52 and the ink absorber 21, which will be described later. Therefore, it is desirable to use an aqueous solution of a high-boiling point solvent, such as glycerin, whose concentration has been adjusted to match that of the inkjet ink, as the humidifying fluid.

[0046] The supply pipe 152 is connected at one end to the humidifying fluid tank 151 and at the other end to the cap portion 13C. More specifically, the supply pipe 152 is connected to a supply port 13Cc provided on the lower surface of the cap portion 13C. The humidifying fluid in the humidifying fluid tank 151 passes through the supply pipe 152 and flows into and is supplied to the cap portion 13C via the supply port 13Cc.

[0047] The supply pump 153 is located downstream of the supply pipe 152 in the direction of supplying humidifying fluid to the humidifying fluid tank 151, and is positioned in the middle of the supply pipe 152 that extends to the cap portion 13C. The supply pump 153 draws in the humidifying fluid from the humidifying fluid tank 151 and discharges the humidifying fluid toward the cap portion 13C. In other words, the supply pump 153 sends the humidifying fluid toward the cap portion 13C. The operation of the supply pump 153 is controlled by the control unit 7.

[0048] The recovery pipe 154 has one end connected to the cap portion 13C and the other end connected to the humidifying fluid tank 151. More specifically, the recovery pipe 154 is connected to a recovery port 13Cd provided on the underside of the cap portion 13C. The humidifying fluid inside the cap portion 13C flows into the recovery pipe 154 through the recovery port 13Cd, is discharged to the outside of the cap portion 13C, and is recovered in the humidifying fluid tank 151.

[0049] Next, the detailed configuration of the cap section 13C will be described. Figures 9, 10, and 11 are explanatory diagrams showing the flow of ink, the flow of humidifying fluid, and the flow of gaseous humidifying fluid within the cap section 13C of Figure 7. In Figure 9, the flow of ink is shown by arrow f1. In Figures 10 and 11, the flow of humidifying fluid (humidifying liquid, gas) is shown by arrow (solid line) f2, and the flow of humidifying fluid (gas only) is shown by arrow (dashed line) f3.

[0050] The cap portion 13C comprises an ink absorber 21, a partition 22, and a humidifying fluid flowing body 23.

[0051] The ink absorber 21 is positioned inside the cap portion 13C. More specifically, the ink absorber 21 is installed at the inner bottom of the concave cap portion 13C. The ink absorber 21 has an outer shape that is rectangular in plan view, adjacent to each of the four inner wall surfaces of the cap portion 13C in the horizontal direction.

[0052] The ink absorber 21 absorbs the ink discharged from the nozzle 521 of the recording head 52. The ink absorber 21 is made of a first porous material through which ink can pass. The ink discharged from the nozzle 521 is held inside the ink absorber 21 by capillary action and does not accumulate on the upper surface of the ink absorber 21 and the partition body 22. The ink absorber 21 plays a role in holding a certain amount of ink discharged from the nozzle 521 during operations such as flushing and purging, and discharging the excess.

[0053] In this embodiment, the first porous material, which is the ink absorber 21, has an average pore size of 70 μm or more and 200 μm or less. From the viewpoint of ink retention and discharge, it is preferable to use the first porous material with this configuration as the ink absorber 21.

[0054] Two discharge ports 21a and 21b are provided on the lower surface of the ink absorber 21. The discharge ports 21a and 21b are located at both ends of the sheet width direction Dw of the ink absorber 21 and are positioned to overlap vertically with the discharge ports 13Ca and 13Cb of the cap portion 13C. Two discharge pipes 141 are individually connected to each of the discharge ports 21a and 21b.

[0055] As shown by the arrow f1 in Figure 9, the ink discharged from the nozzle 521 is absorbed into the ink absorber 21, discharged from inside the cap portion 13C via the discharge portions 21a and 21b, and flows into each of the two discharge pipes 141.

[0056] The partition body 22 is positioned within the cap portion 13C. More specifically, the partition body 22 is installed at the inner bottom of the concave cap portion 13C. The partition body 22 is positioned in the center of the cap portion 13C, at predetermined intervals from each of the four inner wall surfaces in the sheet conveying direction Dc and the sheet width direction Dw, relative to the horizontal direction.

[0057] The partition body 22 is a box-shaped structure with a rectangular parallelepiped exterior, and has an internal space 22S enclosed on the front, back, left, right, top, and bottom by walls. The partition body 22 divides the inside of the cap portion 13C into a first space Sp1 in which the ink absorber 21 is located, and a second space Sp2 which is the internal space 22S.

[0058] The internal space 22S (second space Sp2) of the partition wall 22 is through which the humidifying fluid flows. The partition wall 22 is made of a second porous material through which only gas can pass. The partition wall 22 is impassable to ink and humidifying liquid (the liquid component of the humidifying fluid), but only to gas (the gaseous component of the humidifying fluid). The gaseous component of the humidifying fluid vaporizes from the humidifying fluid and passes through the micropores of the partition wall 22 (second porous material). In other words, the partition wall 22 divides the inside of the cap portion 13C into a first space Sp1 through which ink and humidifying fluid flow, and a second space Sp2 through which only the humidifying fluid flows.

[0059] In other words, the partition wall 22 is formed of a second porous material having a smaller average pore diameter than the first porous material (ink absorber 21). In this embodiment, the second porous material that forms the partition wall 22 has an average pore diameter of 1 μm or more and 20 μm or less. It is preferable to use a second porous material with this configuration as the partition wall 22 in order to allow only the gaseous component of the humidifying fluid to pass through.

[0060] The lower surface of the partition wall 22 is provided with an inlet 22a and an outlet 22b, both of which communicate with the internal space 22S. The inlet 22a is located at the supply port 13Cc of the cap portion 13C, and the supply pipe 152 is connected to it. The outlet 22b is located at the recovery port 13Cd of the cap portion 13C, and the recovery pipe 154 is connected to it.

[0061] As shown by the arrow (solid line) f2 in Figures 10 and 11, the humidifying fluid flows into the internal space 22S (second space Sp2) of the partition wall 22 from the inlet 22a and flows out from the outlet 22b. Also, as shown by the arrow (dashed line) f3 in Figure 11, the gaseous component of the humidifying fluid flows from the second space Sp2 (internal space 22S of the partition wall 22) in the cap section 13C through the partition wall 22 to the first space Sp1.

[0062] This allows the residual ink in the cap section 13C and the ink discharge surface 52F to be humidified without discharging ink from the nozzle 521 into the cap section 13C. In other words, it becomes possible to suppress the drying of the nozzle 521. However, as the vaporization of the humidifying fluid progresses, the humidifying fluid itself dries out, and the humidifying performance deteriorates. For this reason, the control unit 7 drives the supply pump 153 at a predetermined timing to supply new humidifying fluid to the internal space 22S of the partition wall 22 from the inlet 22a (supply port 13Cc) and discharge the old humidifying fluid from the outlet 22b (recovery port 13Cd).

[0063] The humidifying fluid circulating body 23 is located inside the cap portion 13C. More specifically, the humidifying fluid circulating body 23 is located in the internal space 22S (second space Sp2) of the partition wall 22. The humidifying fluid circulating body 23 is formed in the same rectangular parallelepiped shape as the internal space 22S (second space Sp2) of the partition wall 22, when viewed from above.

[0064] The humidifying fluid circulating body 23 is through which the humidifying fluid flowing into the second space Sp2 flows. The humidifying fluid circulating body 23 is made of a third porous material having an average pore diameter greater than or equal to that of the first porous material (ink absorber 21). The humidifying fluid flowing into the second space Sp2 is uniformly distributed throughout the entire humidifying fluid circulating body 23 by the capillary force of the humidifying fluid circulating body 23. The gaseous component of the humidifying fluid vaporizes from the entire humidifying fluid circulating body 23 and moves to the first space Sp1 through the micropores of the partition body 22 (second porous material).

[0065] In this embodiment, the third porous material, which is the humidifying fluid flow body 23, has an average pore diameter of 100 μm or more and 200 μm or less. Since the humidifying fluid has a greater surface tension than the ink, if the average pore diameter of the ink absorber 21 and the humidifying fluid flow body 23 are the same, the flow resistance in the humidifying fluid flow body 23 will be relatively large. From the viewpoint of humidifying fluid retention and substitution, it is preferable to use a third porous material having an average pore diameter greater than or equal to that of the first porous material (ink absorber 21) as the humidifying fluid flow body 23.

[0066] According to the above configuration, a humidifying fluid circulating body 23, made of a third porous material, is positioned in the second space Sp2 through which the humidifying fluid flows within the cap portion 13C. Therefore, the capillary force of the humidifying fluid circulating body 23 makes it possible to uniformly distribute the humidifying fluid throughout the entire area within the humidifying fluid circulating body 23. In other words, even if the ink ejection surface 52F is inclined with respect to the horizontal direction (see Figure 15), the entire area of ​​the ink ejection surface 52F can be uniformly humidified. This makes it possible to prevent clogging of the nozzle 521 and suppress drying of the nozzle 521 with a single cap portion.

[0067] Furthermore, the ink absorber 21 (first porous material), the partition wall 22 (second porous material), and the humidifying fluid flowing body 23 (third porous material) have the strength to not deform when ink is discharged from the nozzle 521 by the ink discharge section 14. Specifically, the ink absorber 21 (first porous material), the partition wall 22 (second porous material), and the humidifying fluid flowing body 23 (third porous material) are formed from materials such as metals like stainless steel or alumina (aluminum oxide), synthetic resins like PPS (polyphenylene sulfide), or ceramics.

[0068] With the above configuration, even if, for example, ink is forcibly discharged from the nozzle 521 by the ink discharge unit 14 to prevent nozzle clogging, and negative pressure is created inside the cap unit 13C, the ink absorber 21, the partition wall 22, and the humidifying fluid flowing body 23 will not deform. As a result, even when the ink discharge unit 14 is operating, it is possible to maintain the first space Sp1 and the second space Sp2 inside the cap unit 13C. In other words, no other members are required to restrict the deformation of the ink absorber 21, the partition wall 22, and the humidifying fluid flowing body 23, and ink purging can be effectively achieved. Therefore, with a configuration that is miniaturized and low-cost, both prevention of nozzle clogging and suppression of nozzle drying can be achieved with a single cap unit 13C.

[0069] Figure 12 is a cross-sectional front view of the recording head 52 and cap portion 13C of the inkjet recording device 1 of Modified Example 1. Figure 13 is a top view of the cap portion 13C of Figure 12. Figure 14 is an exploded perspective view of the ink absorber 24, partition body 22, and humidifying fluid flow body 23 of Figure 12. In the inkjet recording device 1 of Modified Example 1, the cap portion 13C comprises an ink absorber 24, a partition body 22, and a humidifying fluid flow body 23. The lower surface of the ink absorber 24 is provided with discharge portions 24a and 24b, to which two discharge pipes 141 are individually connected.

[0070] The ink absorber 24 has an annular portion 24r and a flat plate portion 24p. The annular portion 24r is formed in an annular shape with a rectangular outer shape in plan view, adjacent to each of the four inner wall surfaces of the cap portion 13C in the horizontal direction. The flat plate portion 24p is positioned above the annular portion 24r and is formed in a rectangular plate shape in plan view, extending across the entire horizontal area within the cap portion 13C. The flat plate portion 24p is positioned to cover the upper surface of the partition body 22. The flat plate portion 24p also faces the ink discharge surface 52F in the vertical direction across its entire horizontal area.

[0071] Thus, the ink absorber 24 is positioned between the ink discharge surface 52F and the partition wall 22. More specifically, the flat portion 24p of the ink absorber 24 is positioned between the ink discharge surface 52F and the partition wall 22.

[0072] With the above configuration, the ink discharged from the nozzle 521 can be held in the ink absorber 24 (flat plate portion 24p) directly below the nozzle 521. The ink remaining in the flat plate portion 24p can then be humidified by the gaseous component of the humidifying fluid that has passed through the micropores of the partition body 22. Furthermore, the humidified ink remaining in the flat plate portion 24p can humidify the ink discharge surface 52F over its entire horizontal surface.

[0073] Furthermore, as shown in Figure 14, the ink absorber 24, the partition wall 22, and the humidifying fluid circulating body 23 are formed in a stacked structure in the vertical direction, with roughly plate-shaped members extending horizontally. The ink absorber 24, the partition wall 22, and the humidifying fluid circulating body 23 are formed as a single unit. The multiple roughly plate-shaped members constituting the ink absorber 24, the partition wall 22, and the humidifying fluid circulating body 23 are formed as a single unit by methods such as welding and bonding (e.g., ultrasonic welding, laser welding, heat welding, adhesive, etc., the method is not limited). This configuration offers advantages such as a reduction in the number of parts, miniaturization (thinning) of parts, and reduction in labor costs during replacement.

[0074] Figure 15 is a cross-sectional front view of the recording head 52 and cap portion 13C of the inkjet recording device 1 of Modified Example 2. In the inkjet recording device 1 of Modified Example 2, the recording head 52 is positioned with the ink ejection surface 52F inclined with respect to the horizontal direction. Although not shown, the transport surface of the transport path that transports the sheet S on which ink is ejected, which is positioned opposite the ink ejection surface 52F, is also positioned inclined with respect to the horizontal direction. In this embodiment, the ink ejection surface 52F is inclined at an angle of 60 degrees with respect to the horizontal direction, for example.

[0075] The cap portion 13C is positioned opposite the ink ejection surface 52F, parallel to it. That is, the cap portion 13C extends in a direction inclined with respect to the horizontal direction and is formed in a rectangular, oval, or other shape. The cap portion 13C is detachable from the ink ejection surface 52F, which is inclined with respect to the horizontal direction, and covers the ink ejection surface 52F.

[0076] By arranging the ink ejection surface 52F, i.e., the recording head 52, at an angle, the inkjet recording device 1 can be miniaturized. With the above configuration, in the inkjet recording device 1 which has been miniaturized in this way, the maintenance unit 11 can be further miniaturized and its cost reduced, and both the prevention of nozzle clogging 521 and the suppression of nozzle drying 521 can be achieved with a single cap portion 13C.

[0077] Furthermore, as described above, by providing a humidifying fluid circulating body 23 made of a third porous material in the second space Sp2 through which the humidifying fluid flows within the cap portion 13C, it is possible to uniformly distribute the humidifying fluid throughout the entire area of ​​the humidifying fluid circulating body 23, even when the ink ejection surface 52F is inclined with respect to the horizontal direction. As a result, in an inkjet recording device 1 in which the recording head 52 is tilted to reduce the overall size of the device, uniform humidification can be achieved over the entire area of ​​the ink ejection surface 52F.

[0078] Although embodiments of the present invention have been described above, the scope of the present invention is not limited thereto, and various modifications can be made to implement the invention without departing from the spirit of the invention. [Industrial applicability]

[0079] This invention is applicable to inkjet recording devices. [Explanation of Symbols]

[0080] 1. Inkjet recording device 5. Records Section 6 Drying section 7 Control Unit 11 Maintenance Unit 12 Unit Movement Mechanism 13 Cap Unit 13C Cap 14. Ink ejection section 15 Humidification section 21 Ink absorber 22 Partition body 22S interior space 23 Humidifying fluid distributor 24 Ink absorber 24p flat plate part 24r Circular section 51 Head Unit 52 recording heads 52F Ink ejection surface 141 Discharge pipe 142 Discharge pump 143 Waste liquid tank 151 Humidifying fluid tank 152 Supply pipe 153 Supply pump 154 Recovery pipe 521 Nozzle S Sheet (Recording medium) Sp1 1st space Sp2 2nd space

Claims

1. A recording head having an ink ejection surface from which nozzles for ejecting ink onto a recording medium open, A cap portion that is detachable from the ink ejection surface and covers the ink ejection surface, An ink discharge unit connected to the cap portion, which discharges the ink from the nozzle via the cap portion and discharges the ink inside the cap portion to the outside, A humidifying unit that supplies a humidifying fluid containing humidifying liquid and gas into the cap portion attached to the ink ejection surface, Equipped with, The aforementioned cap portion is A partition body is disposed within the cap portion and divides the cap portion into a first space through which the ink and the humidifying fluid flow, and a second space through which only the humidifying fluid flows. An ink absorber arranged in the first space to absorb the ink, A humidifying fluid circulator arranged in the second space through which the humidifying fluid flows, Equipped with, The ink absorber is formed of a first porous material through which the ink can pass. The partition wall is formed of a second porous material having a smaller average pore diameter than the first porous material through which only the gas can pass. The inkjet recording apparatus is characterized in that the humidifying fluid flow body is formed of a third porous material having an average pore diameter greater than or equal to that of the first porous material.

2. The inkjet recording apparatus according to claim 1, characterized in that the ink absorber is disposed between the ink discharge surface and the partition wall.

3. The inkjet recording apparatus according to claim 1, characterized in that the ink absorber and the partition body are formed as a single unit.

4. The ink discharge unit is characterized by having a pump that applies negative pressure to the cap portion attached to the ink discharge surface to suck out the ink inside the cap portion, as described in claim 1.

5. The inkjet recording apparatus according to claim 4, characterized in that the first porous material, the second porous material, and the third porous material have strength that prevents deformation when the ink is discharged by the ink discharge unit.

6. The inkjet recording apparatus according to claim 1, characterized in that the average pore diameter of the first porous material is 70 μm or more and 200 μm or less, the average pore diameter of the second porous material is 1 μm or more and 20 μm or less, and the average pore diameter of the third porous material is 100 μm or more and 200 μm or less.

7. The inkjet recording apparatus according to any one of claims 1 to 6, characterized in that it comprises a recording head inclined with respect to the horizontal direction on which the ink ejection surface is located.

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