Liquid discharge device and ink discharge device

Abstract

An ink discharge device (1) has an ink discharge head (3) and an ink receiving part (8) for receiving ink discharged from a nozzle of the ink discharge head (3). The ink receiving part (8) is provided with: a cleaning liquid storage section (120) provided with a recessed section (121) in which a cleaning liquid (C) is stored; and an overflow liquid inflow section (122) into which the cleaning liquid (C) overflowing from the recessed section (121) flows. The ink discharged from the nozzle lands on a liquid surface (C1) of the cleaning liquid (C) stored in the recessed section (121).

Description

Liquid ejection device and ink ejection device

[0001] The present invention relates to a liquid ejection device and an ink ejection device.

[0002] In devices that eject liquids such as ink, a discharge operation called flushing has been performed to prevent the nozzles of the head from drying out and to stabilize the ink meniscus at the tip of the nozzle. Ink ejection devices that perform flushing are provided with an ink receiver that receives the ink ejected by flushing.

[0003] If ink remains and accumulates on the surface of the ink receiving section, it becomes impossible to maintain an appropriate distance between the head nozzle and the ink receiving section, causing problems. For example, if the distance between the nozzle and the ink receiving section is too great, the ejected ink will turn into mist and contaminate the surrounding area. Conversely, if the distance between the nozzle surface and the ink receiving section is too close, the ink that lands will bounce back and contaminate the head surface.

[0004] Patent Document 1 describes a structure in which ink ejected by flushing is received by foam that has absorbed cleaning liquid, preventing ink from remaining in a receiving portion. The foam contained in the flushing box is supplied with cleaning liquid from a reservoir, so the foam absorbs the cleaning liquid. The ink ejected onto the surface of the foam is sucked into the bottom of the flushing box and discharged together with the cleaning liquid by suctioning the space at the bottom of the flushing box with a pump.

[0005] Japanese Patent Application Laid-Open No. 2023-134902

[0006] In Patent Document 1, ink and cleaning liquid are sucked downwards by creating a negative pressure in the space below the foam, which makes it difficult for ink to remain on the ink receiving surface. However, a mechanism for suctioning from below the foam is required. Furthermore, because cleaning liquid is sucked and discharged along with the ink, new cleaning liquid must be supplied from a reservoir each time suction is performed from below the foam. Therefore, a cleaning liquid reservoir and supply pump are required in addition to the flushing box, making the structure complicated.

[0007] In view of the above, the present invention aims to suppress problems caused by the residue of thickened and solidified ejection liquid while providing a mechanism for receiving ejection liquid such as ink ejected by flushing with a simple structure.

[0008] In order to solve the above problem, the ink ejection device of the present invention has an ink ejection head and an ink receiving section that receives ink ejected from the nozzles of the ink ejection head, and the ink receiving section has a cleaning liquid storage section that has a recess in which cleaning liquid is stored, and an overflow liquid inlet section into which the cleaning liquid that has overflowed from the recess flows, and is characterized in that the ink ejected from the nozzle lands on the liquid surface of the cleaning liquid stored in the recess.

[0009] In order to solve the above problems, the liquid ejection device of the present invention has a liquid ejection head and a liquid receiving portion that receives liquid ejected from a nozzle of the liquid ejection head, and the liquid receiving portion has a cleaning liquid storage portion that has a recess in which cleaning liquid is stored, and an overflow liquid inlet portion into which the cleaning liquid that has overflowed from the recess flows, and is characterized in that the liquid ejected from the nozzle lands on the liquid surface of the cleaning liquid stored in the recess.

[0010] According to the present invention, the ejected liquid lands on the surface of the cleaning liquid and immediately mixes with the cleaning liquid. Furthermore, when the cleaning liquid is replenished, not only the cleaning liquid but also the ejected liquid mixed with the cleaning liquid overflows. Therefore, despite the simple structure that does not include a mechanism for removing the ejected liquid using power or a dedicated mechanism for suctioning the ejected liquid, there is little risk of the ejected liquid remaining in the liquid receiver in a thickened or solidified state. Furthermore, even if an excessive amount of cleaning liquid is injected when refilling, the specified liquid volume is achieved. Therefore, there is no need to check the liquid volume when refilling the cleaning liquid, and the cleaning liquid will not overflow in unintended locations, reducing the maintenance burden.

[0011] In the present invention, the ink receiving section preferably includes a three-dimensional structure having a void through which the cleaning liquid passes, the three-dimensional structure being disposed in the recess and immersed below the surface of the cleaning liquid, and the liquid ejected from the nozzle preferably lands on the surface of the cleaning liquid at a position where the three-dimensional structure is immersed. The presence of the three-dimensional structure below the surface of the cleaning liquid thus suppresses swaying of the cleaning liquid. Therefore, the liquid surface sway caused by air currents generated near the liquid surface due to the scanning of the ink ejection head or vibrations of the ink receiving section is small, reducing the risk of the cleaning liquid spilling outside the cleaning liquid storage section. Furthermore, although there is a concern about splashing of the cleaning liquid when ink lands on the liquid surface, the presence of the three-dimensional structure below the liquid surface reduces this splashing. Furthermore, the ink mixed with the cleaning liquid flows down the interior of the three-dimensional structure and mixes with the cleaning liquid passing through the interior of the three-dimensional structure, which tends to dilute the ink concentration. Therefore, there is little risk of the ink remaining in the ink receiving section in a thickened or solidified state.

[0012] In the present invention, the three-dimensional structure is preferably a three-dimensional lattice structure. As a result of experiments using various three-dimensional structures, the inventors have found that when a three-dimensional lattice structure is used, the swaying of the liquid surface is smallest.

[0013] In the present invention, the three-dimensional structure is preferably a porous body with an open cell structure. Even when a porous body is used, the fluctuation of the liquid surface can be reduced compared to when no porous body is placed under the liquid surface. In addition, the splashing of the cleaning liquid can be reduced.

[0014] In the present invention, the porous body preferably has an open cell structure in which the number of cells, which is the average number of pores intersecting a straight line 25 mm long in any direction, is 8 or less. With this specification, the cleaning liquid mixed with the ink can easily pass through the inside of the foam material, and the ink is less likely to thicken and solidify inside the foam material.

[0015] In the present invention, it is preferable that the distance between the liquid surface and the three-dimensional structure when the maximum amount of the cleaning liquid is stored in the recess is 4 mm or less. By reducing the distance between the liquid surface and the three-dimensional structure, it is possible to reduce the swaying of the liquid surface and suppress the splashing of the cleaning liquid.

[0016] In the present invention, when the outflow direction is a direction perpendicular to the up-down direction in which the ink ejection head and the ink receiving portion face each other and perpendicular to the scanning direction of the ink ejection head, it is preferable that the overflow liquid inlet portion be provided at a position adjacent to the recess in the outflow direction. The fluctuation of the liquid surface of the cleaning liquid is greater in the scanning direction than in the direction perpendicular to the scanning direction. Therefore, by overflowing in the direction with less fluctuation, it is possible to avoid excessive overflow and a reduction in the amount of liquid stored in the recess.

[0017] In the present invention, the ink receiving section preferably includes a partition wall that separates the overflow liquid inlet section from the recess, and a groove formed by cutting out the upper end of the partition wall. This allows the groove wall to function as an outlet, so the height of the cleaning liquid surface can be determined by the shape of the groove wall. Furthermore, there is little risk of the cleaning liquid spilling outside the overflow liquid inlet section. Furthermore, even if the top of the overflow liquid inlet section is blocked, the cleaning liquid can still overflow.

[0018] In the present invention, the ink receiving section preferably includes an outer wall section that surrounds the recess and the overflow liquid inlet section, and a cover plate that is supported on the upper end of the outer wall section and covers the top of the overflow liquid inlet section, the cover plate having an opening that overlaps the recess, and ink ejected from the nozzle passes through the opening and hits the liquid surface. This prevents overflowing cleaning liquid from spilling outside and prevents foreign matter from falling into the overflow liquid inlet section. Furthermore, since cleaning liquid can be replenished through the opening, there is no need to provide a separate refill port.

[0019] In the present invention, the cover plate is preferably provided with a protrusion that protrudes upward along the edge of the opening, which makes it difficult for the cleaning liquid to spill out of the opening even if the surface of the cleaning liquid is disturbed by air currents or vibrations.

[0020] In the present invention, it is preferable that the cleaning liquid storage section includes an overflow liquid receiving section provided below the recess and the overflow liquid inlet section, and that a hole penetrating the bottom of the overflow liquid inlet section is located above the overflow liquid receiving section. In this way, by utilizing the space below the recess, it is possible to reduce the planar size of the ink receiving section while ensuring the volume of the overflow liquid receiving section.

[0021] In the present invention, it is preferable that the ink ejection device 1 further includes a head cap that covers the nozzles of the ink ejection head, an ink suction flow path connected to the head cap, a pump that sucks the inside of the head cap via the ink suction flow path, a waste liquid storage unit that is connected to the head cap via the ink suction flow path, and a cleaning liquid discharge flow path that connects the overflow liquid receiver and the waste liquid storage unit. In this way, the waste liquid storage unit can be shared by a mechanism that creates negative pressure inside the head cap to suck ink from the nozzles and a mechanism that receives ink ejected by flushing, thereby simplifying the ink ejection device 1.

[0022] In the present invention, the ink is preferably UV-curable ink. UV-curable ink tends to thicken and solidify easily, but in this embodiment, problems caused by ink ejected by flushing thickening and solidifying and remaining in the ink receiving section can be suppressed.

[0023] According to the present invention, the ejected liquid that hits the surface of the cleaning liquid immediately mixes with the cleaning liquid. Furthermore, if an excessive amount of cleaning liquid is poured in when refilling the tank, the cleaning liquid mixed with the ejected liquid will overflow. Therefore, despite the simple structure that does not include a mechanism for removing the ejected liquid using power or a dedicated mechanism for suctioning the ejected liquid, there is little risk of the ejected liquid remaining in the liquid receptacle in a thickened or solidified state. Furthermore, there is no need to check the liquid level when refilling the cleaning liquid, and it does not overflow into unintended locations, reducing the burden of maintenance.

[0024] 1 is an explanatory diagram showing the configuration of an ink ejection device; 2 is a cross-sectional view of an ink receiving section; 3 is a perspective view showing the cover plate, three-dimensional structure, and flushing receiving section assembled; 4 is an exploded perspective view of the cover plate, three-dimensional structure, and flushing receiving section as viewed from above; 5 is an exploded perspective view of the cover plate, three-dimensional structure, and flushing receiving section as viewed from below; 6 is a plan view of the flushing receiving section and the three-dimensional structure; 7 is a cross-sectional view (cross-sectional view taken at position C-C in FIG. 3) showing the cover plate, three-dimensional structure, and flushing receiving section assembled; 8 is a cross-sectional view of an ink receiving section of a reference embodiment; 9 is a perspective view of the flushing receiving section, foam material, and pressure plate; 10 is a perspective view of the flushing receiving section and foam material; 11 is a perspective view of the flushing receiving section as viewed from above; 12 is a perspective view of the flushing receiving section as viewed from below; 13 is a cross-sectional view (cross-sectional view taken at position A-A in FIG. 3) of the flushing receiving section, foam material, and pressure plate; 10A and 10B are explanatory diagrams of a cleaning liquid refilling process, a residual ink removing process, and a foam material according to a modified example.

[0025] Hereinafter, an embodiment of a liquid ejection device to which the present invention is applied will be described with reference to the drawings. In this specification, an ink ejection device 1 that ejects UV-curable ink that is cured by irradiation with ultraviolet (UV) rays will be described as an embodiment of the liquid ejection device. Note that the ink ejected by the ink ejection device 1 may be an ink other than UV-curable ink.

[0026] (Ink Discharge Device) Figure 1 is an explanatory diagram showing the configuration of an ink discharge device 1. The ink discharge device 1 is a printing device that performs printing by discharging ink toward a print medium 2. The ink discharge device 1 includes an ink discharge head 3, a head scanning mechanism (not shown) that moves the ink discharge head 3 back and forth in a main scanning direction CR, a transport mechanism 4 that transports the print medium 2 in a transport direction PF that is perpendicular to the main scanning direction CR, a UV light irradiation unit (not shown), and a nozzle maintenance mechanism 5.

[0027] The transport mechanism 4 has a transport surface 6 that faces the print medium 2 in the Z direction, which is perpendicular to the main scanning direction CR and perpendicular to the transport direction PF. In this embodiment, the Z direction is the up-and-down direction. The transport mechanism 4 transports the print medium 2, for example, while adsorbing it to the transport surface 6. The ink ejection device 1 ejects ink while moving the ink ejection head 3 relative to the print medium 2 in the main scanning direction CR in conjunction with the transport operation of the print medium 2. Thereafter, the UV light irradiation unit is driven to irradiate UV light onto the ink ejected onto the surface of the print medium 2, thereby curing the ink. The UV light irradiation unit is, for example, mounted on a carriage (not shown) together with the ink ejection head 3, and moves back and forth in the main scanning direction CR together with the ink ejection head 3.

[0028] The nozzle maintenance mechanism 5 is a mechanism for performing flushing and suctioning ink from the nozzles. The nozzle maintenance mechanism 5 includes, for example, an ink receiving unit 8 and a head cap 9 that are arranged adjacent to the transport surface 6 in the main scanning direction CR, and a waste liquid storage unit 10 that is connected to the ink receiving unit 8 and the head cap 9. The head scanning mechanism moves the ink ejection head 3 within a range that includes a flushing position 3A that faces the ink receiving unit 8 and a capping position 3B that faces the head cap 9.

[0029] The ink ejection device 1 performs flushing by moving the ink ejection head 3 to the flushing position 3A at a predetermined timing and ejecting ink toward the ink receiving unit 8. Flushing is performed at various times. For example, flushing is performed each time the ink ejection head 3 moves back and forth once in the main scanning direction CR while ejecting ink toward the print medium 2. Alternatively, flushing is performed immediately before returning from a standby state and starting to eject ink toward the print medium 2 based on new print data. A cleaning liquid discharge flow path 12 is connected to the bottom of the ink receiving unit 8. Ink ejected during flushing is discharged from the ink receiving unit 8 together with cleaning liquid, which will be described later. The nozzle maintenance mechanism 5 directs the ink ejected during flushing and cleaning liquid into the waste liquid storage unit 10 via the cleaning liquid discharge flow path 12 and stores them there.

[0030] The ink ejection device 1 moves the ink ejection head 3 to the capping position 3B at a predetermined timing and covers the nozzle surface 11 with the head cap 9. This forms an airtight space around the nozzle surface 11. A pump 7 is provided in an ink suction flow path 13 that connects the head cap 9 to a waste liquid storage section 10. When the pump 7 is driven, a negative pressure is created in the airtight space inside the head cap 9, so that ink inside the nozzles is sucked in and discharged into the head cap 9. The sucked ink flows into the waste liquid storage section 10 via the ink suction flow path 13.

[0031] For example, when the ink ejection device 1 finishes ejecting ink onto the print medium 2 and enters a standby state, the nozzle surface 11 is covered with the head cap 9. This prevents the ink in the nozzles from drying out during standby. The pump 7 is then driven at a predetermined timing to suck out the ink. For example, when new print data is received, the pump 7 is driven to suck out the ink in the nozzles before starting to eject ink onto the print medium 2.

[0032] (Ink Receiving Section) The configuration of the ink receiving section 8 to which the present invention is applied will now be described. FIG. 2 is a cross-sectional view of the ink receiving section 8. FIG. 3 is a perspective view showing the cover plate 140, the three-dimensional structure 130, and the flushing receiving section 150 assembled together. FIG. 4 is an exploded perspective view of the cover plate 140, the three-dimensional structure 130, and the flushing receiving section 150 as viewed from above. FIG. 5 is an exploded perspective view of the cover plate 140, the three-dimensional structure 130, and the flushing receiving section 150 as viewed from below. FIG. 6 is a plan view of the flushing receiving section 150 and the three-dimensional structure 130. FIG. 7 is a cross-sectional view showing the cover plate 140, the three-dimensional structure 130, and the flushing receiving section 150 assembled together, taken along the line CC in FIG. 3.

[0033] In this specification, the X direction, Y direction, and Z direction are directions that are perpendicular to one another. One side of the Y direction is the Y1 direction, and the other side of the Y direction is the Y2 direction. One side of the Z direction is the Z1 direction, and the other side of the Z direction is the Z2 direction. When the ink receiving section 8 is mounted on the ink ejection device 1, the Z direction coincides with the up-down direction, the Z1 direction coincides with the downward direction, and the Z2 direction coincides with the upward direction. Furthermore, the CR direction coincides with the X direction, and the PF direction coincides with the Y direction.

[0034] As shown in FIG. 2, the ink receiving section 8 includes a cleaning liquid storage section 120, a three-dimensional structure 130, and a cover plate 140. The cleaning liquid storage section 120 has a recess 121 recessed in the Z1 direction (downward). Cleaning liquid C is stored in the recess 121. The three-dimensional structure 130 is disposed in the recess 121 and is immersed below the surface of the cleaning liquid C. Note that in FIG. 2, only the outer shape of the three-dimensional structure 130 is shown by dashed lines, and the internal structure of the three-dimensional structure 130 is not shown. Also, part of the structure of the cleaning liquid storage section 120 is not shown in FIG. 2. Specifically, the second wall portion 159Y shown in FIG. 7 is not shown.

[0035] The three-dimensional structure 130 is a block material having a roughly rectangular parallelepiped shape. The three-dimensional structure 130 is supported on the bottom surface of the recess 21. The height T1 of the three-dimensional structure 130 in the Z direction is smaller than the depth T2 of the recess 21. Therefore, when the maximum amount of cleaning liquid C is stored in the recess 21, the upper end 131 of the three-dimensional structure 130 is located below the liquid surface of the cleaning liquid C.

[0036] 2, the height T1 of the three-dimensional structure 130 in the Z direction and the depth T2 of the recess 21 are set to dimensions that allow the distance T3 between the liquid surface C1 of the cleaning liquid C and the three-dimensional structure 130 to be an appropriate distance. The appropriate distance T3 is 4 mm or less. Although T1 and T2 are not particularly limited, it is preferable to set them so that T3≦4 mm.

[0037] The cover plate 140 is fixed to the upper end of the cleaning liquid reservoir 120. The cover plate 140 has an opening 141 that penetrates an area that overlaps with the recess 121 when viewed from the Z2 direction. Therefore, when the ink receiving section 8 is viewed from above, the liquid level C1 of the cleaning liquid C is exposed inside the opening 141. The cover plate 140 has a protrusion 142 that protrudes in the Z2 direction along the edge of the opening 141. The protrusion 142 has a constant height and surrounds the entire periphery of the opening 141. This reduces the risk of the cleaning liquid C overflowing from the opening 141 when the liquid level C1 of the cleaning liquid C is shaken by vibrations or air currents.

[0038] The shape of the opening 141 corresponds to the planar shape of the nozzle surface 11 of the ink ejection head 3. When flushing is performed, the ink ejection head 3 is positioned so that the nozzle surface 11 faces the area inside the opening 141. Therefore, ink ejected from the nozzle passes through the opening 141 and lands on the liquid surface C1 of the cleaning liquid C.

[0039] The three-dimensional structure 130 is disposed at a position that overlaps with the opening 141 when viewed from the Z direction. Therefore, when flushing is performed, ink ejected from the nozzle lands in the area below the liquid surface where the three-dimensional structure 130 is disposed.

[0040] 4 and 5 , the three-dimensional structure 130 has a gap 132 therein through which the cleaning liquid C passes. When flushing is performed, the ink that lands on the liquid surface C1 of the cleaning liquid C immediately mixes with the cleaning liquid C. The cleaning liquid C mixed with the ink enters the gap 132 of the three-dimensional structure 130. Therefore, ink does not accumulate on the upper end 131 of the three-dimensional structure 130.

[0041] The three-dimensional structure 130 of this embodiment is a three-dimensional lattice structure. As shown in Figures 5, 6, and 7, the three-dimensional structure 130 includes lattice members 133 that extend parallel to each other in the X direction, Y direction, and Z direction and intersect with each other. Each lattice member 133 has a square cross section. Voids 132 are gaps between adjacent lattice members 133.

[0042] The thickness of the lattice material 133, the width of the gaps therebetween, and the cross-sectional shape of the lattice material 133 may be different from those in this embodiment. Furthermore, the three-dimensional structure 130 is not limited to a lattice structure, and may be any structure that has voids 132 through which the cleaning liquid passes. For example, a grid structure or a honeycomb structure may be used.

[0043] The three-dimensional structure 130 may also be a porous body with an open-cell structure having interconnected cells. Specifically, a foam material such as a soft polyurethane foam with a large amount of cells can be used as the porous body. When using a foam material, it is preferable that the size of the cells is large. For example, it is preferable to use a foam material with a cell count of 8 or less, which is the average number of pores intersecting a straight line 25 mm long in any direction.

[0044] 6, the area that overlaps with the opening 141 when viewed from the Z direction is indicated by a dashed line. As shown in Fig. 6, the three-dimensional structure 130 of this embodiment has a planar shape that is larger than the opening 141 when viewed from the Z direction, but the planar shape of the three-dimensional structure 130 does not have to be this size. For example, multiple three-dimensional structures 130 whose planar shape is smaller than the opening 141 may be arranged inside the recess 121.

[0045] 6 , the entire opening 141 overlaps with the three-dimensional structure 130 when viewed from the Z direction, but it is sufficient that at least a portion of the opening 141 overlaps with the three-dimensional structure 130. However, it is preferable that most of the opening 141 overlaps with the three-dimensional structure 130. For example, it is preferable that half or more of the area of ​​the opening 141 overlaps with the three-dimensional structure 130.

[0046] As shown in FIG. 2 , the cleaning liquid reservoir 120 includes a flushing receiver 150 having a recess 121, and a holder 160 that holds the flushing receiver 150. The holder 160 includes a bottom 161 located in the Z1 direction relative to the bottom 151 of the flushing receiver 150, and a wall 162 extending in the Z2 direction from the outer periphery of the bottom 161. A step 163 facing in the Z2 direction is provided on the inner surface of the wall 162. The wall 162 includes an inclined portion 164 that extends from the step 163 in the Z2 direction. The inclined portion 164 is inclined in a direction that widens outward as it extends in the Z2 direction. The flushing receiver 150 is housed inside the inclined portion 164 and is supported by the step 163.

[0047] The flushing receiving portion 150 includes overflow liquid inlet portions 122 provided on both sides of the recess 121 in the Y direction. When the amount of liquid in the recess 121 increases due to ink landing on the liquid surface C1 of the cleaning liquid C stored in the recess 121, the cleaning liquid C mixed with the ink overflows, thereby maintaining a constant amount of liquid in the recess 121. Furthermore, as shown in FIG. 7 , when new cleaning liquid C is poured onto the three-dimensional structure 130 through the opening 141 to replenish the liquid, the excess cleaning liquid C overflows.

[0048] The cleaning liquid reservoir 120 includes an overflow liquid inlet 122 and an overflow liquid receiver 123 that receives the cleaning liquid C below the recess 121. In this embodiment, the space between the bottom 151 of the flushing receiver 150 and the bottom 161 of the holder 160 is the overflow liquid receiver 123.

[0049] 2 and 5 , the flushing receiver 150 is provided with a hole 152 that penetrates the bottom of the overflow liquid inlet 122. The cleaning liquid C that overflows from the recess 121 flows out in the Z1 direction from the hole 152 of the overflow liquid inlet 122 and accumulates in the overflow liquid receiver 123. The cleaning liquid C is then discharged from the cleaning liquid discharge flow path 12 connected to the bottom 161 of the holder 160 and accumulated in the waste liquid reservoir 10.

[0050] As shown in Figures 4, 5, and 6, the flushing receiving portion 150 includes a pair of outer wall portions 154 extending in the X direction, a pair of partition wall portions 153 extending in the X direction inside the pair of outer wall portions 154, and a pair of side wall portions 157 extending in the Y direction. Both ends of the partition wall portions 153 and the outer wall portion 154 in the X direction are connected to the side wall portions 157. As a result, a recess 121 opening in the Z2 direction is formed inside the partition wall portions 153 and the side wall portions 157. In addition, overflow liquid inlet portions 122 opening in the Z2 direction are formed on both sides of the recess 121 in the Y direction. The overflow liquid inlet portions 122 are formed between the partition wall portions 153 and the outer wall portions 154 and are separated from the recess 121 by the partition wall portions 153.

[0051] 4, a plurality of grooves 155 are cut out in the Z1 direction (downward) at the upper end of the partition wall 153. The cleaning liquid C in the recess 121 flows out from the grooves 155 to the overflow liquid inlet 122. Therefore, when the maximum amount of cleaning liquid C is stored in the recess 121, the height of the liquid surface C1 coincides with the height of the bottom of the grooves 155.

[0052] As shown in FIG. 6 , the overflow liquid inlet portions 122 are disposed on both sides of the recess 121 in the Y direction. This arrangement is intended to align the outflow direction of the cleaning liquid C during overflow (i.e., the Y direction) with the direction in which the liquid surface C1 of the cleaning liquid C oscillates least. When the ink ejection head 3 scans immediately before flushing, an airflow in the CR direction is generated as the ink ejection head 3 moves. Therefore, the liquid surface C1 of the cleaning liquid C oscillates more in the CR direction and less in the direction perpendicular to the CR direction (the Y direction). If the direction in which the oscillates least is aligned with the outflow direction of the cleaning liquid C during overflow, it is possible to prevent the cleaning liquid C from overflowing more than necessary due to the oscillating liquid surface C1.

[0053] The pair of outer wall portions 154 and the pair of side wall portions 157 that form the outer peripheral surface of the flushing receiving portion 150 are inclined outward in the Z2 direction. Furthermore, the upper ends of the pair of outer wall portions 154 and the pair of side wall portions 157 are provided with frame portions 158 shaped to fit the cover plate 140 inside. Therefore, the cover plate 140 is supported by the upper ends of the pair of outer wall portions 154 and the pair of side wall portions 157. As shown in FIG. 2 , the cover plate 140 blocks the overflow liquid inlet portion 122 from above.

[0054] As shown in FIGS. 4 , 6 , and 7 , the flushing receiving portion 150 includes an inner wall portion 159 that surrounds the three-dimensional structure 130 placed in the recess 121. The inner wall portion 159 includes a pair of first walls 159X that extend in the Y direction on both sides of the three-dimensional structure 130 in the X direction, and a second wall portion 159Y that extends in the X direction in the Y1 direction of the three-dimensional structure 130. The Y2-direction ends of the pair of first walls 159X are spaced apart from the partition wall 153. Therefore, when the amount of liquid inside the inner wall portion 159 increases by pouring new cleaning liquid C onto the three-dimensional structure 130 to replenish it, the cleaning liquid C flows between the Y2-direction end of the first wall portion 159X and the partition wall 153 to the outer periphery of the inner wall portion 159, as shown by arrow F1 in FIG. 6 .

[0055] A plurality of ribs 156 extending in the X direction are arranged at regular intervals in the Y direction on the outer side of the inner wall 159 in the X direction. Each of the plurality of ribs 156 is connected to a side wall 157 and is spaced apart from the inner wall 159. Therefore, the cleaning liquid C that has flowed out to the outer periphery of the inner wall 159 flows through the gap between the ribs 156 and the inner wall 159 to the gap between the second wall 159Y and the partition 153. Therefore, as shown in FIG. 7 , even if the second wall 159Y is arranged between the three-dimensional structure 130 and the partition 153, excess cleaning liquid C flows into both the overflow liquid inlet 122 on the Y2 side of the recess 121 and the overflow liquid inlet 122 on the Y1 side of the recess 121.

[0056] 4 , the height in the Z direction of the inner wall portion 159, the height in the Z direction of the partition wall portion 153, and the height in the Z direction of the rib 156 are all the same. Therefore, the cover plate 140 is supported by the upper end of the inner wall portion 159, the upper end of the partition wall portion 153, and the upper end of the rib 156. The upper ends of the partition wall portion 153 and the rib 156 are provided with protrusions 143 that protrude in the Z2 direction. The protrusions 143 fit into holes 144 provided on the outer periphery of the cover plate 140.

[0057] As shown in Fig. 6 , the opening 141 overlaps with the central region of the inner wall portion 159 in the X direction. The three-dimensional structure 130 is disposed inside the inner wall portion 159, and the movement range in the X direction is restricted by the inner wall portion 159. Furthermore, the movement range of the three-dimensional structure 130 in the Y direction is restricted by the inner wall portion 159 and the partition portion 153. In this embodiment, the three-dimensional structure 130 is held at a position overlapping with the opening 141 by the inner wall portion 159 and the partition portion 153.

[0058] The structure that regulates the position of the three-dimensional structure 130 is not limited to the shape of the inner wall portion 159 of this embodiment. For example, the height of the inner wall portion 159 in the Z direction may be shorter than in this embodiment. Furthermore, the length of the second wall portion 159Y in the X direction and the length of the first wall portion 159X in the Y direction may be shorter than in this embodiment, and the first wall portion 159X and the second wall portion 159Y may not be connected. Alternatively, the inner wall portion 159 may not be provided. For example, the three-dimensional structure 130 may be fixed to or formed integrally with the bottom portion 151 of the flushing receiving portion 150.

[0059] (Replenishing cleaning liquid) When the amount of cleaning liquid C stored in the recess 21 decreases due to drying or the like, new cleaning liquid C is poured into the recess 121 through the opening 141 to replenish the liquid, as shown in FIG. 7 . The new cleaning liquid C is poured onto the three-dimensional structure 130, so it enters the void 132. Therefore, the ink concentration of the cleaning liquid C that has entered the inside of the void 132 becomes diluted. The cleaning liquid C mixed with ink flows out of the void 132 to the outside of the three-dimensional structure 130. As described above, part of the cleaning liquid C mixed with ink flows to the outside of the inner wall 159.

[0060] If the amount of liquid replenished is excessive, the excess cleaning liquid C will overflow to both sides in the Y direction of the recess 121. Therefore, even if the amount of liquid in the recess 121 is not checked, the cleaning liquid C injected in excess will overflow, so the cleaning liquid C will not overflow outside the ink receiving section 8, and the appropriate amount can be easily replenished.

[0061] In this embodiment, the ink lands on the liquid surface C1 of the cleaning liquid C and immediately mixes with the cleaning liquid C, so the ink does not accumulate on the three-dimensional structure 130. Even if flushing is performed when the liquid volume has decreased due to drying or the like, and as a result some of the ink remains on the upper end 131 of the three-dimensional structure 130, when the cleaning liquid C is replenished, the ink can be washed down into the void portion 132 by pouring the cleaning liquid C over the remaining ink.

[0062] (Operation and Effect) As described above, the ink ejection device 1 of this embodiment has the ink ejection head 3 and the ink receiving section 8 that receives ink ejected from the nozzles of the ink ejection head 3. The ink receiving section 8 has a cleaning liquid storage section 120 provided with a recess 121 in which cleaning liquid C is stored, and an overflow liquid inlet section 122 into which cleaning liquid C that overflows from the recess 121 flows. Ink ejected from the nozzles lands on the liquid surface C1 of the cleaning liquid C stored in the recess 121.

[0063] In this embodiment, when flushing is performed, ink lands on the liquid surface C1 of the cleaning liquid C, and the ink and cleaning liquid C immediately mix. Furthermore, if an excessive amount of cleaning liquid C is poured when refilling the cleaning liquid C, the cleaning liquid C mixed with the ink will overflow. Therefore, even though the structure is simple and does not include a mechanism for removing ink using power or a dedicated mechanism for sucking ink, there is little risk of ink remaining in a thickened and solidified state in the ink receiving section 8. Furthermore, there is no need to check the liquid level when refilling the cleaning liquid C, and the cleaning liquid C will not overflow in unintended places, reducing the burden of maintenance.

[0064] The ink receiving section 8 of this embodiment includes a three-dimensional structure 130 having a void 132 through which the cleaning liquid C passes. The three-dimensional structure 130 is disposed in the recess 121 and immersed below the surface of the cleaning liquid C. Ink ejected from the nozzle lands on the liquid surface C1 at the position where the three-dimensional structure 130 is immersed below the surface of the cleaning liquid C. In this manner, the presence of the three-dimensional structure 130 below the surface of the cleaning liquid C can suppress swaying of the cleaning liquid C. Therefore, air currents generated near the liquid surface C1 due to scanning of the ink ejection head 3 and swaying of the liquid surface C1 caused by vibration of the ink receiving section 8 are small, so there is little risk of the cleaning liquid C spilling outside the cleaning liquid storage section 120. Furthermore, although there is a concern about rebounding of the cleaning liquid C when ink lands on the liquid surface C1, the presence of the three-dimensional structure 130 below the liquid surface can reduce this rebounding. Furthermore, when the ink mixed with the cleaning liquid C flows down inside the three-dimensional structure 130, it mixes with the cleaning liquid C passing through the inside of the three-dimensional structure 130, so the ink concentration is likely to be diluted. Therefore, there is little risk that the ink will remain in the ink receiving section 8 in a thickened and solidified state.

[0065] The three-dimensional structure 130 of this embodiment is a three-dimensional lattice structure. The inventors have examined the magnitude of the swaying of the liquid surface C1 using various three-dimensional structures 130. As a result, it has been confirmed that the swaying of the liquid surface C1 is smallest when a three-dimensional lattice structure is used.

[0066] As described above, a porous body with an open cell structure can also be used as the three-dimensional structure 130. Among the reference embodiments described later, the modified example shown in Fig. 17 is provided with an overflow liquid inlet 22, and ink lands at a location where the porous body is immersed below the surface of the cleaning liquid C, and therefore corresponds to an embodiment of the present invention.

[0067] Even when a porous body is used, the fluctuation of the liquid surface C1 can be reduced compared to when no porous body is placed below the liquid surface. Also, the rebound of the cleaning liquid C can be reduced. When a porous body is used as the three-dimensional structure 130, it is preferable that the porous body has an open cell structure with a cell count of 8 or less, which is the average number of pores intersecting a straight line 25 mm long in any direction. With these specifications, the cleaning liquid mixed with the ink can easily pass through the interior of the foam material, and the ink is less likely to thicken or solidify inside the foam material.

[0068] In this embodiment, the distance T3 between the liquid surface C1 when the maximum amount of cleaning liquid C is stored in the recess 121 and the three-dimensional structure 130 is 4 mm or less. By shortening the distance T3 between the liquid surface C1 and the three-dimensional structure 130, it is possible to reduce the fluctuation of the liquid surface C1 and suppress the splashing of the cleaning liquid C.

[0069] In this embodiment, when the outflow direction (Y direction) is a direction orthogonal to the up-down direction (Z direction) in which the ink ejection head 3 and the ink receiving portion 8 face each other and orthogonal to the CR direction, which is the scanning direction of the ink ejection head 3, the overflow liquid inlet portion 122 is provided at a position adjacent to the recess 121 in the outflow direction (Y direction). The fluctuation of the liquid surface C1 of the cleaning liquid C is small in the direction (Y direction) orthogonal to the CR direction. Therefore, by overflowing in a direction with less fluctuation, it is possible to avoid excessive overflow and a rapid decrease in the amount of liquid stored in the recess 121.

[0070] The ink receiving section 8 of this embodiment includes a partition wall 153 that separates the overflow liquid inlet section 122 and the recess 121, and a groove 155 that is formed by cutting out the upper end of the partition wall 153. Therefore, the groove 155 serves as an outlet, and the height of the liquid surface C1 of the cleaning liquid C can be determined by the shape of the groove 155. Furthermore, because the outflowing cleaning liquid C collects in the groove 155, there is little risk of the cleaning liquid C spilling outside the overflow liquid inlet section 122. Furthermore, even if the top of the overflow liquid inlet section 122 is blocked, the cleaning liquid C can overflow.

[0071] The ink receiving section 8 of this embodiment includes a pair of outer wall portions 154 and a pair of side wall portions 157 as outer wall portions surrounding the outer peripheries of the recess 121 and the overflow liquid inlet portion 122. The ink receiving section 8 also includes a cover plate 140 that is supported on the upper ends of the pair of outer wall portions 154 and the pair of side wall portions 157 and covers the top of the overflow liquid inlet portion 122. The cover plate 140 has an opening 141 at a position overlapping the recess 121. Ink ejected from the nozzle passes through the opening 141 and lands on the liquid level C1. This prevents overflowing cleaning liquid C from spilling outside and prevents foreign matter from falling into the overflow liquid inlet portion 122. Furthermore, since cleaning liquid C can be replenished through the opening 141, there is no need to provide a separate refill port.

[0072] In this embodiment, the cover plate 140 is provided with a protrusion 142 that protrudes upward along the edge of the opening 141. Therefore, even if the liquid surface C1 of the cleaning liquid C is shaken by air currents or vibrations, the cleaning liquid C is unlikely to spill out of the opening 141.

[0073] In this embodiment, the cleaning liquid storage section 120 includes an overflow liquid receiving section 123 provided below the recess 121 and the overflow liquid inlet section 122. A hole 152 penetrating the bottom of the overflow liquid inlet section 122 is located above the overflow liquid receiving section 123. In this way, by utilizing the space below the recess 121, the planar size of the ink receiving section 8 can be reduced while ensuring the volume of the overflow liquid receiving section 123.

[0074] In this embodiment, the ink ejection head 3 includes a head cap 9 that covers the nozzles of the ink ejection head 3, an ink suction flow path 13 connected to the head cap 9, a pump 7 that sucks the inside of the head cap 9 via the ink suction flow path 13, a waste liquid storage section 10 that is connected to the head cap 9 via the ink suction flow path 13, and a cleaning liquid C discharge flow path that connects the overflow liquid receiver and the waste liquid storage section 10. This allows the waste liquid storage section 10 to be shared by both the mechanism that creates negative pressure inside the head cap 9 to suck ink from the nozzles and the mechanism that receives ink ejected by flushing, thereby simplifying the configuration.

[0075] In this embodiment, the ink is UV-curable ink. UV-curable ink tends to thicken and solidify easily, but in this embodiment, problems caused by ink ejected by flushing thickening and solidifying and remaining in the ink receiving section 8 can be suppressed.

[0076] Other Embodiments (1) The above embodiment may be configured such that the three-dimensional structure 130 is not disposed in the recess 121 and only the cleaning liquid C is stored in the recess 121 .

[0077] (2) The above embodiment does not necessarily have to include the cover plate 140. For example, as long as the distance in the Z direction from the upper end of the cleaning liquid reservoir 120 to the liquid surface C1 of the cleaning liquid C can be secured, the risk of the cleaning liquid C spilling outside the flushing receiving portion 150 can be reduced even if the cover plate 140 is not provided.

[0078] (3) In the above embodiment, the present invention is applied to the ink ejection device 1, but the present invention can also be applied to liquid ejection devices that eject liquid other than ink. That is, the present invention can take the following embodiment 2. The configurations adopted in the above embodiment and their modifications can all be applied to the following embodiment 2. (Embodiment 2) A liquid ejection device comprising: a liquid ejection head; and a liquid receiving portion that receives liquid ejected from a nozzle of the liquid ejection head; the liquid receiving portion comprising: a cleaning liquid storage portion provided with a recess for storing cleaning liquid; and an overflow liquid inlet portion into which the cleaning liquid that overflows from the recess flows; and the liquid ejected from the nozzle lands on the surface of the cleaning liquid stored in the recess.

[0079] (Reference embodiment) A reference embodiment of the ink receiving section will be described below. The reference embodiment can be applied to the ink ejection device 1 of the above embodiment. Fig. 8 is a cross-sectional view of the ink receiving section 8 of the reference embodiment. Fig. 9 is a perspective view of the flushing receiving section 50, foam material 30, and presser plate 40. Fig. 10 is a perspective view of the flushing receiving section 50 and foam material 30. Fig. 11 is a perspective view of the flushing receiving section 50 seen from above. Fig. 12 is a perspective view of the flushing receiving section 50 seen from below. Figs. 13 and 14 are cross-sectional views of the flushing receiving section 50, foam material 30, and presser plate 40. Fig. 13 is a cross-sectional view taken along line A-A in Fig. 9. Fig. 14 is a cross-sectional view taken along line B-B in Fig. 9.

[0080] As shown in Figure 8, the ink receiving section 8 of the reference embodiment includes a cleaning liquid storage section 20, a foam material 30, and a presser plate 40. The cleaning liquid storage section 20 has a recess 21 recessed in the Z1 direction (downward). The presser plate 40 is fixed to the upper end of the cleaning liquid storage section 20. The presser plate 40 has an opening 41 that penetrates a portion that overlaps with the recess 21 when viewed from the Z2 direction. The surface 31 of the foam material 30 arranged in the recess 21 is exposed at the center of the upper end surface of the ink receiving section 8 through the opening 41. When flushing is performed, ink ejected from the nozzles of the ink ejection head 3 lands on the surface 31 of the foam material 30.

[0081] As shown in Figure 9, the opening 41 of the pressure plate 40 is a rectangle whose dimension in the X direction is smaller than its dimension in the Y direction. The shape of the opening 41 corresponds to the shape of the nozzle surface 11. For example, the opening 41 is larger than the nozzle surface 11. As shown in Figures 9 and 10, the dimensions of the foam material 30 in both the X direction and the Y direction are larger than those of the opening 41. Therefore, the inner peripheral edge of the opening 41 of the pressure plate 40 overlaps the outer peripheral portion of the foam material 30 all around. The pressure plate 40 functions as a pressing member that holds the foam material 30 so that it does not expand in the Z2 direction.

[0082] As shown in Figure 8, cleaning liquid C is stored in recess 21. Foam material 30 is supported on the bottom surface of recess 21 and is immersed in cleaning liquid C. Because foam material 30 is a porous body with open cells formed therein, foam material 30 is impregnated with cleaning liquid C. Ink that has landed on surface 31 of foam material 30 moves by gravity through the cells of foam material 30 to liquid surface C1, where it mixes with cleaning liquid C.

[0083] The foam material 30 is a porous material with an open cell structure. For example, the foam material 30 is a polyurethane foam with an open cell structure. The foam material 30 is preferably a soft polyurethane foam with a large amount of air bubbles, and the air bubbles are preferably large. In the reference embodiment, a foam material 30 having a cell count of 8 or less, which is the average number of voids intersecting a 25 mm long straight line in any direction, is used.

[0084] As shown in FIG. 14 , in the reference embodiment, the thickness T1 of the foam material 30 is greater than the depth T2 of the recess 21, and the surface 31 of the foam material 30 is located above the liquid level C1 of the cleaning liquid C. Therefore, the ink receiving section 8 is configured to receive ink via the surface 31 of the foam material 30. The thickness T1 of the foam material 30 and the depth T2 of the recess 21 are set so that the distance T3 between the liquid level C1 of the cleaning liquid C and the surface 31 of the foam material 30 is an appropriate distance. The appropriate distance T3 is 4 mm or less. For example, if the depth T2 of the recess 21 is 6 mm, the thickness T1 of the foam material 30 is set to 10 mm or less. This ensures that the distance T3 between the liquid level C1 and the surface 31 of the foam material 30 is 4 mm or less.

[0085] In the reference embodiment, the depth T2 of the recess 21 is 6 mm, and the thickness T1 of the foam material 30 is 10 mm. Therefore, 60% of the thickness T1 of the foam material 30 is immersed in the cleaning solution C. It is preferable that at least half of the thickness T1 of the foam material 30, and preferably 60% or more of the thickness T1 of the foam material 30, is immersed in the cleaning solution C. Note that the depth T2 of the recess 21 is not limited to 6 mm, but it is preferable that the depth T2 of the recess 21 and the thickness T1 of the foam material 30 be set so as to satisfy the above-mentioned appropriate distance (T3≦4 mm).

[0086] As shown in Figure 8, the cleaning liquid reservoir 20 includes a flushing receiver 50 having a recess 21, and a holder 60 that holds the flushing receiver 50. The holder 60 includes a bottom 61 located in the Z1 direction (downward) relative to the flushing receiver 50, and a wall 62 extending in the Z2 direction (upward) from the outer periphery of the bottom 61. The wall 62 is inclined so as to widen outward as it extends in the Z2 direction (upward). A step 63 that protrudes inward is provided on the inner surface of the wall 62. The flushing receiver 50 is housed inside the wall 62 and is supported by the step 63.

[0087] 10 , 11 , and 12 , the flushing receiving portion 50 includes a pair of outer wall portions 54 extending in the Y direction, a pair of inner wall portions 53 extending in the Y direction inside the pair of outer wall portions 54, and a pair of side wall portions 57 extending in the X direction. Both Y-direction ends of the inner wall portions 53 and the outer wall portions 54 are connected to the side wall portions 57. As a result, a recess 21 opening in the Z2 direction is formed inside the inner wall portions 53 and the side wall portions 57. The outer wall portions 54 and the side wall portions 57 are inclined toward the outer periphery as they extend in the Z2 direction (upward). As shown in FIG. 10 , a rib 56 protrudes in the Y direction from the inner surface of the side wall portion 57 to position the foam material 30 placed in the recess 21 in the Y direction.

[0088] A frame portion 58 shaped to fit the presser plate 40 is provided on the upper ends of the pair of outer wall portions 54 and the pair of side wall portions 57. A protrusion is formed on the tip of the inner wall portion 53 for fixing the presser plate 40 by welding. Note that, since Figures 8, 13, and 14 are diagrams that schematically show the cross-sectional configuration, the frame portion 58 is not shown.

[0089] In the flushing receiving section 50, overflow liquid inlet sections 22 are provided between inner wall sections 53 and outer wall sections 54 on both sides of the recessed section 21 in the X direction. As shown in Figures 8 and 9, the upper ends of the overflow liquid inlet sections 22 are blocked by presser plates 40. As shown in Figures 11 and 12, the upper ends of each inner wall section 53 are provided with a plurality of grooves 55 cut out in the Z1 direction (downward). In the flushing receiving section 50, when the amount of liquid increases as a result of ink that has landed on the surface 31 of the foam material 30 flowing down to the liquid level C1 of the cleaning liquid C, the cleaning liquid C mixed with the ink overflows from the grooves 55, thereby maintaining a constant amount of liquid.

[0090] 8, the cleaning liquid reservoir 20 includes an overflow liquid inlet 22 and an overflow liquid receiver 23 that receives the cleaning liquid C below the recess 21. In the reference embodiment, the space between the bottom 51 of the flushing receiver 50 and the bottom 61 of the holder 60 serves as the overflow liquid receiver 23.

[0091] 8 and 12 , the flushing receiving section 50 is provided with a hole 52 that penetrates the bottom of the overflow liquid inlet section 22. The cleaning liquid C mixed with ink flows out in the Z1 direction (downward) from the hole 52 of the overflow liquid inlet section 22 and accumulates in the overflow liquid receiving section 23. The cleaning liquid C is then discharged from the cleaning liquid discharge flow path 12 connected to the bottom 61 of the holder 60 and accumulated in the waste liquid storage section 10.

[0092] (Replenishing Cleaning Liquid) FIG. 15 is an explanatory diagram of the cleaning liquid replenishing process. FIG. 16 is an explanatory diagram of the residual ink removal process. As shown in FIG. 15 , when the amount of cleaning liquid C stored in the recess 21 decreases due to drying or the like, cleaning liquid C is supplied to the surface 31 of the foam material 30. Because the foam material 30 has an open-cell structure, cleaning liquid C passes through the foam material 30 and flows into the recess 21. As described above, the flushing receiving section 50 has a structure that allows cleaning liquid C to overflow. Therefore, even without checking the amount of liquid in the recess 21, cleaning liquid C injected in excess will overflow, so cleaning liquid C will not overflow outside the ink receiving section 8 and the appropriate amount can be easily replenished.

[0093] As shown in Figure 15, if residual ink P remains on the surface 31 of the foam material 30, when refilling the cleaning liquid C, the residual ink P can be washed away by pouring the cleaning liquid C onto the surface 31 of the foam material 30.

[0094] (Removal of Residual Ink) If residual ink P remains on the surface 31 of the foam material 30, as shown in Figure 16, a removal tool 70 can be used to cause the residual ink P to react with the cleaning liquid C impregnated in the foam material 30. As described above, in the reference embodiment, the foam material 30 is soft, the bubbles are large, and the distance between the liquid surface C1 and the surface 31 is small. Therefore, by simply pressing the area where the residual ink P remains with the tool 70, the residual ink P can be brought into contact with the liquid surface C1 and removed.

[0095] (Operation and Effect) As described above, the ink ejection device 1 of the reference embodiment has the ink ejection head 3 and the ink receiving section 8 that receives ink ejected from the nozzles of the ink ejection head 3. The ink receiving section 8 includes a cleaning liquid storage section 20 that is provided with a recess 21 in which cleaning liquid C is stored, and a foam material 30 that is placed in the recess 21. At least a portion of the foam material 30 is immersed in the cleaning liquid C. The ink ejected from the nozzle lands on the surface 31 of the foam material 30 that is above the liquid level C1 of the cleaning liquid C.

[0096] In the reference embodiment, the foam material 30 onto which the ink lands is immersed in the cleaning liquid C, so the ink is easily absorbed by the foam material 30 and easily mixes with the cleaning liquid C. The ink also easily flows down inside the foam material 30 and reaches the liquid surface C1. Therefore, even though the structure is simple and does not include a mechanism for removing ink using power or a dedicated mechanism for sucking ink, there is little risk of ink remaining and accumulating in the ink receiving section 8.

[0097] The ink receiving section 8 of the reference embodiment uses a foam material 30 that is a porous material with an open cell structure and has a cell count of 8 or less, which is the average number of pores that intersect a 25 mm long straight line in any direction. The inventors produced prototype ink receiving sections 8 using various foam materials 30 with different structures and pore sizes, and performed flushing. As a result, they confirmed that when foam materials 30 with such specifications are used, ink is less likely to solidify on the surface 31 of the foam material 30, and the air bubbles in the foam material 30 are less likely to be filled with ink. On the other hand, they confirmed that when foam materials 30 with 13 or more cells are used, ink is less likely to penetrate into the foam material, and the air bubbles are filled and accumulate on the surface.

[0098] Furthermore, when foam material 30 having the same specifications as the reference embodiment was used, it was confirmed that when refilling cleaning liquid C, it was poured onto surface 31 of foam material 30 and quickly absorbed and replenished into recesses 21. It was also confirmed that even if ink remained on surface 31 or inside foam material 30, this ink was washed away together with cleaning liquid C and removed.

[0099] In the reference embodiment, the distance T3 between the liquid level C1 when the maximum amount of cleaning liquid C is stored in the recess 21 and the surface 31 of the foam material 30 is an appropriate dimension (4 mm or less). This makes it short the distance that ink that lands on the surface 31 of the foam material 30 passes through the bubbles of the foam material 30 due to gravity and reaches the liquid level C1. Therefore, the ink is less likely to solidify between reaching the liquid level C1 and mixing with the cleaning liquid C, and therefore less likely to remain on the surface 31 of the foam material 30 or in the bubbles.

[0100] In the reference embodiment, the depth T2 of the cleaning liquid C immediately after it overflows from the recess 21 is set to 60% or more of the thickness T1 of the foam material 30. When half or more, preferably 60% or more, of the foam material 30 is immersed in the cleaning liquid C in this way, the distance T3 between the liquid level C1 and the surface 31 of the foam material 30 becomes small. Therefore, ink is less likely to remain on the surface 31 of the foam material 30 or in the air bubbles.

[0101] The ink receiving section 8 of the reference embodiment is equipped with a presser plate 40 that presses down on the edge of the foam material 30 that is above the liquid level C1 of the cleaning liquid C. This prevents the foam material 30 from expanding and improves the positional accuracy of the surface 31, making it possible to maintain a small distance between the foam material 30 and the nozzle surface 11. If the distance between the foam material 30 and the nozzle surface 11 is small, the ink ejected from the nozzles lands on the foam material 30 before turning into mist. This makes it possible to suppress contamination by ink mist.

[0102] The cleaning liquid reservoir 20 of the reference embodiment is provided with an overflow liquid inlet 22 into which the cleaning liquid C that overflows from the recess 21 flows. Therefore, when refilling the cleaning liquid C, even if an excessive amount is poured, the specified amount of liquid can always be maintained. Therefore, there is no need to check the amount of liquid when refilling the cleaning liquid C, and the cleaning liquid C will not spill outside the ink receiving section 8, reducing the burden of maintenance.

[0103] The cleaning liquid reservoir 20 of the reference embodiment includes an inner wall 53 surrounding both sides of the recess 21 in the X direction and an outer wall 54 surrounding the inner wall 53. The overflow liquid inlet 22 is located between the inner wall 53 and the outer wall 54. Furthermore, a pressure plate 40 is provided that is supported on the upper end of the outer wall 54 and covers the upper part of the overflow liquid inlet 22. The pressure plate 40 has an opening 41 that overlaps the recess 21, and the inner peripheral edge of the opening 41 overlaps the edge of the foam material 30. This prevents overflowing cleaning liquid C from spilling to the outside and prevents foreign matter from falling into the overflow liquid inlet 22. Furthermore, by using the pressure plate 40 as a lid to cover the upper part of the overflow liquid inlet 22, the number of parts can be reduced and the configuration can be simplified. Furthermore, cleaning liquid C can be refilled through the opening 41 of the pressure plate 40, eliminating the need for a separate refill port.

[0104] The cleaning liquid reservoir 20 of the reference embodiment has a groove 55 formed by cutting out the upper end of the inner wall 53, so that the cleaning liquid C can overflow from the groove 55 even when the upper part of the overflow liquid inlet 22 is blocked by the retaining plate 40. In this case, the height of the liquid level C1 when overflowing can be determined by the shape of the groove 55.

[0105] The cleaning liquid storage section 20 of the reference embodiment includes an overflow liquid receiving section 23 provided below the recess 21 and the overflow liquid inlet section 22, and a hole 52 penetrating the bottom of the overflow liquid inlet section 22 is located above the overflow liquid receiving section 23. In this way, by utilizing the space below the recess 21, the planar size of the ink receiving section 8 can be reduced while ensuring the volume of the overflow liquid receiving section 23.

[0106] The ink ejection device 1 of the reference embodiment has a head cap 9 that covers the nozzles of the ink ejection head 3, an ink suction flow path 13 connected to the head cap 9, a pump 7 that sucks the inside of the head cap 9 via the ink suction flow path 13, a waste liquid storage section 10 that is connected to the head cap 9 via the ink suction flow path 13, and a cleaning liquid discharge flow path 12 that connects an overflow liquid receiver 23 to the waste liquid storage section 10. In this way, by sharing the waste liquid storage section 10 between the mechanism that sucks ink from the nozzles and the mechanism that receives ink ejected by flushing, the configuration can be simplified.

[0107] The ink ejection device 1 of the reference embodiment ejects UV-curable ink. UV-curable ink tends to thicken and solidify easily, but even when UV-curable ink is used, the reference embodiment can prevent problems caused by ink ejected by flushing thickening and solidifying and remaining in the ink receiving section 8.

[0108] (Modification) Figure 17 is an explanatory diagram of a modification of the foam material 30. Figure 17 shows a configuration example in which the thickness T2 of the foam material 30 is smaller than the depth T2 of the recess 21. In this case, the entire foam material 30 is immersed in the cleaning liquid C, and the surface 31 of the foam material 30 is located below the liquid level C1 of the cleaning liquid C. Ink ejected from the nozzle lands on the liquid level C1 at the location where the foam material 30 is immersed below the liquid level C1 of the cleaning liquid C.

[0109] 17, the distance T3 between the liquid level C1 of the cleaning liquid C and the surface 31 of the foam material 30 is preferably 4 mm or less. For example, if the depth T2 of the recess 21 is 6 mm, the thickness T1 of the foam material 30 is set to 2 mm or more, preferably 3 mm or more.

[0110] When ink lands on the liquid surface C1 of the cleaning liquid C, the ink mixes directly with the cleaning liquid C, so the ink does not solidify and does not accumulate. Therefore, even though the structure is simple and does not include a mechanism for removing ink using power, there is little risk of ink remaining and accumulating in the ink receiving section 8. Note that when ink lands on the liquid surface C1, there is a concern that the cleaning liquid C may bounce back, but this can be reduced by having the ink land at a location where the foam material 30 is located below the liquid surface C1 of the cleaning liquid C. If the distance T3 between the liquid surface C1 and the surface 31 of the foam material 30 is an appropriate dimension (for example, 4 mm or less), there is little risk of the ink bouncing back.

[0111] (Other Reference Forms) (1) The above-mentioned reference form has an overflow liquid inlet 22 and an overflow liquid receiving section 23 as a structure that prevents the cleaning liquid C that overflows from the recess 21 from spilling outside the ink receiving section 8, but the ink receiving section 8 may also have a structure that does not have the overflow liquid inlet 22 or the overflow liquid receiving section 23.

[0112] (2) The above-described reference embodiment includes a presser plate 40 that presses down the foam material 30, but the structure may also include no presser plate 40. Furthermore, the presser member that presses down the foam material 30 is not limited to the presser plate 40. For example, the presser plate 40 does not have to double as a lid that closes the overflow liquid inlet portion 22.

[0113] (3) The configuration of the above-mentioned reference embodiment can be applied to a liquid ejection device that ejects an ejection liquid other than ink. That is, the following reference embodiment 2 can be adopted. Furthermore, the configuration adopted in the above-mentioned reference embodiment and its variations can all be applied to the following reference embodiment 2. (Reference embodiment 2) A liquid ejection device comprising: a liquid ejection head; and an ejection liquid receiving portion that receives liquid ejected from a nozzle of the liquid ejection head; the ejection liquid receiving portion comprises a cleaning liquid storage portion having a recess for storing cleaning liquid, and a foam material disposed in the recess; at least a portion of the foam material is immersed in the cleaning liquid; and the liquid ejected from the nozzle lands on a surface of the foam material that is above the liquid surface of the cleaning liquid, or on the liquid surface at a portion where the foam material is immersed below the liquid surface of the cleaning liquid.

[0114] As described above, this specification discloses the following Supplementary Notes 1 to 12 as reference forms. (Supplementary Note 1) A liquid ejection device comprising: a liquid ejection head; and a ejected liquid receiving section that receives liquid ejected from a nozzle of the liquid ejection head, wherein the ejected liquid receiving section comprises a cleaning liquid storage section having a recess for storing cleaning liquid, and a foam material placed in the recess, wherein at least a portion of the foam material is immersed in the cleaning liquid, and wherein the liquid ejected from the nozzle lands on a surface of the foam material that is above the surface of the cleaning liquid, or on the surface of the cleaning liquid at a location where the foam material is immersed below the surface of the cleaning liquid.

[0115] (Appendix 2) An ink ejection device comprising an ink ejection head and an ink receiving section that receives ink ejected from the nozzles of the ink ejection head, wherein the ink receiving section comprises a cleaning liquid storage section having a recess for storing cleaning liquid, and a foam material placed in the recess, wherein at least a portion of the foam material is immersed in the cleaning liquid, and wherein the ink ejected from the nozzle lands on a surface of the foam material that is above the liquid surface of the cleaning liquid, or on the liquid surface at a location where the foam material is immersed below the liquid surface of the cleaning liquid.

[0116] According to Supplementary Note 1 and Supplementary Note 2, a discharged liquid such as ink is landed on the surface of a foam material immersed in cleaning liquid or on the surface of the cleaning liquid at the location where the foam material is immersed. If the foam material on which the discharged liquid lands is immersed in cleaning liquid, the foam material absorbs a large amount of the discharged liquid, making it easier for the discharged liquid to mix with the cleaning liquid and flow down the interior of the foam material to reach the surface of the cleaning liquid. Furthermore, when the discharged liquid lands on the surface of the cleaning liquid, it directly mixes with the cleaning liquid. Therefore, despite the simple structure that does not include a mechanism for removing the discharged liquid using power or a dedicated mechanism for suctioning the discharged liquid, there is little risk of the discharged liquid remaining in a thickened or solidified state. Furthermore, even when the discharged liquid lands on the surface of the cleaning liquid, there is little risk of the cleaning liquid bouncing back because the foam material is present below the surface of the cleaning liquid.

[0117] (Appendix 3) The ink ejection device described in Appendix 1, characterized in that the foam material is a porous body with an open cell structure and the number of cells, which is the average number of pores intersecting a straight line in any direction with a length of 25 mm, is 8 or less.

[0118] The inventors conducted experiments using various foam materials and confirmed that when using a foam material with the specifications of Appendix 3, ink easily flows down the inside of the foam material and is less likely to thicken or solidify on the surface or inside of the foam material. Furthermore, even if ink remains on the surface of the foam material, it can be washed away by pouring a cleaning liquid onto the surface.

[0119] (Appendix 4) The ink ejection device according to appendix 3, wherein the distance between the liquid level when the maximum amount of the cleaning liquid is stored in the recess and the surface of the foam material is 4 mm or less.

[0120] According to Supplementary Note 4, when the foam material is above the liquid surface, the ink that lands on the surface of the foam material flows down a short distance to the liquid surface. Therefore, the ink is less likely to thicken or solidify between reaching the liquid surface and mixing with the cleaning liquid, so the ink is less likely to remain on the surface of the foam material or in the bubbles. Furthermore, when the foam material is submerged below the liquid surface, the short distance between the liquid surface and the foam material can prevent the cleaning liquid from splashing back.

[0121] (Supplementary Note 5) The ink ejection device according to Supplementary Note 3, wherein the depth of the cleaning liquid when the maximum amount of the cleaning liquid is stored in the recess is 60% or more of the thickness of the foam.

[0122] By increasing the depth of the cleaning liquid, the distance between the liquid surface and the surface of the foam material is reduced, and therefore, according to Appendix 5, ink is less likely to remain on the surface of the foam material or in the bubbles.

[0123] (Appendix 6) The ink ejection device according to any one of appendices 2 to 5, further comprising a pressing member for pressing down an edge of the foam material that is above the liquid surface.

[0124] According to Supplementary Note 6, the expansion of the foam material can be suppressed, and the positional accuracy of the foam material surface can be improved. This allows the distance between the foam material and the nozzle surface to be kept small. If the distance between the foam material and the nozzle surface is small, the ink ejected from the nozzle lands on the foam material before turning into mist. Therefore, contamination by ink mist can be suppressed.

[0125] (Supplementary Note 7) In the ink ejection device according to any one of Supplementary Note 2 to Supplementary Note 5, the cleaning liquid storage section includes an overflow liquid inlet section into which the cleaning liquid that has overflowed from the recessed section flows.

[0126] According to Supplementary Note 7, even if an excessive amount of cleaning liquid is poured when refilling, the liquid volume will be the specified volume. Therefore, there is no need to check the liquid volume when refilling the cleaning liquid, and the liquid will not overflow into unintended places, reducing the burden of maintenance.

[0127] (Appendix 8) The ink ejection device described in Appendix 7 is characterized in that the cleaning liquid storage section has an inner wall section that surrounds the recess and an outer wall section that surrounds the outer periphery of the inner wall section, the overflow liquid inlet section is provided between the inner wall section and the outer wall section, and further has a pressure plate that is supported on the upper end of the outer wall section and covers the top of the overflow liquid inlet section, and the pressure plate has an opening that overlaps the recess, and the inner peripheral edge of the opening overlaps the edge of the foam material.

[0128] According to Appendix 8, by using the retaining plate as a lid to cover the top of the overflow liquid inlet, it is possible to prevent overflowing cleaning liquid from spilling outside and to prevent foreign matter from falling into the overflow liquid inlet. Furthermore, since cleaning liquid can be refilled through the opening, there is no need to provide a separate refill port. Furthermore, since the edge of the opening can press the entire edge of the foam material, it is possible to reduce the bulging of the surface of the foam material and shorten the distance between the foam material and the nozzle surface.

[0129] (Supplementary Note 9) The ink ejection device according to Supplementary Note 8, further comprising a groove formed by cutting out an upper end of the inner wall portion.

[0130] According to Supplementary Note 9, even if the overflow liquid inlet is blocked by the pressing plate, the cleaning liquid can be made to overflow from the groove. In addition, the height of the liquid surface when overflowing can be determined by the shape of the groove.

[0131] (Appendix 10) The ink ejection device described in Appendix 7 is characterized in that the cleaning liquid storage section has an overflow liquid receiving section provided below the recess and the overflow liquid inlet section, and a hole section penetrating the bottom of the overflow liquid inlet section is located above the overflow liquid receiving section.

[0132] According to Supplementary Note 10, by utilizing the space below the recess, it is possible to reduce the planar size of the ink receiving portion while ensuring the volume of the overflow liquid receiving portion.

[0133] (Appendix 11) An ink ejection device as described in Appendix 10, characterized in that it comprises: a head cap that covers the nozzles of the ink ejection head; an ink suction flow path connected to the head cap; a pump that sucks the inside of the head cap via the ink suction flow path; a waste liquid storage section connected to the head cap via the ink suction flow path; and a cleaning liquid discharge flow path that connects the overflow liquid receiving section and the waste liquid storage section.

[0134] According to Appendix 11, the waste liquid storage section can be shared between the mechanism that creates negative pressure inside the head cap to suck ink from the nozzles and the mechanism that receives ink ejected by flushing, thereby simplifying the configuration.

[0135] (Appendix 12) The ink ejection device according to any one of appendices 2 to 5, wherein the ink is a UV curable ink.

[0136] UV curable ink tends to thicken and solidify easily, but in this embodiment, problems caused by ink ejected by flushing thickening and solidifying and remaining in the ink receiving section can be suppressed.

Claims

1. An ink ejection device comprising an ink ejection head and an ink receiving section that receives ink ejected from the nozzles of said ink ejection head, wherein said ink receiving section comprises a cleaning liquid storage section having a recess for storing cleaning liquid, and an overflow liquid inlet section into which said cleaning liquid overflows from said recess, and wherein ink ejected from said nozzles lands on the surface of said cleaning liquid stored in said recess.

2. The ink ejection device described in claim 1, characterized in that the ink receiving section has a three-dimensional structure with a void section through which the cleaning liquid passes, the three-dimensional structure is placed in the recess and immersed below the surface of the cleaning liquid, and the liquid ejected from the nozzle lands on the surface of the cleaning liquid at a position where the three-dimensional structure is immersed below the surface of the cleaning liquid.

3. The ink ejection device according to claim 2, wherein the three-dimensional structure is a three-dimensional lattice structure.

4. The ink ejection device according to claim 2, wherein the three-dimensional structure is a porous body with an open cell structure.

5. The ink discharge device according to claim 4, wherein the porous body has an open cell structure in which the number of cells, which is the average number of pores intersecting a straight line of 25 mm in any direction, is 8 or less.

6. The ink ejection device according to claim 2, wherein the distance between the liquid surface when the maximum amount of cleaning liquid is stored in the recess and the three-dimensional structure is 4 mm or less.

7. An ink ejection device as described in claim 1, characterized in that, when the outflow direction is a direction perpendicular to the vertical direction in which the ink ejection head and the ink receiving portion face each other and perpendicular to the scanning direction of the ink ejection head, the overflow liquid inlet portion is provided at a position adjacent to the recess in the outflow direction.

8. An ink ejection device according to claim 7, characterized in that the ink receiving section is provided with a partition wall that separates the overflow liquid inlet section and the recess, and a groove is provided by cutting out the upper end of the partition wall.

9. The ink ejection device according to claim 7, wherein the ink receiving section comprises an outer wall section that surrounds the outer periphery of the recess and the overflow liquid inlet section, and a cover plate that is supported on the upper end of the outer wall section and covers the top of the overflow liquid inlet section, the cover plate having an opening at a position that overlaps with the recess, and the ink ejected from the nozzle passes through the opening and lands on the liquid surface.

10. The ink ejection device according to claim 9, wherein the cover plate is provided with a protrusion that protrudes upward along the edge of the opening.

11. An ink ejection device as described in claim 1, characterized in that the cleaning liquid storage section has an overflow liquid receiving section provided below the recess and the overflow liquid inlet section, and a hole section penetrating the bottom of the overflow liquid inlet section is located above the overflow liquid receiving section.

12. An ink ejection device as described in claim 11, characterized in that it comprises: a head cap that covers the nozzles of the ink ejection head; an ink suction flow path connected to the head cap; a pump that sucks the inside of the head cap via the ink suction flow path; a waste liquid storage section that is connected to the head cap via the ink suction flow path; and a cleaning liquid discharge flow path that connects the overflow liquid receiving section and the waste liquid storage section.

13. The ink ejection device according to any one of claims 1 to 11, wherein the ink is a UV curable ink.

14. A liquid ejection device comprising a liquid ejection head and a liquid receiving section that receives liquid ejected from a nozzle of said liquid ejection head, wherein said liquid receiving section comprises a cleaning liquid storage section having a recess for storing cleaning liquid, and an overflow liquid inlet section into which said cleaning liquid overflows from said recess, and wherein said liquid ejected from said nozzle lands on the surface of said cleaning liquid stored in said recess.

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