Liquid ejection device, liquid ejection system, and method for cleaning a liquid ejection device

Abstract

To provide a liquid discharge device capable of improving a cleaning property of a nozzle opening surface of a liquid discharge head.SOLUTION: Provided is a liquid discharge device including: a liquid discharge nozzle that discharges liquid; a housing that holds a plurality of liquid discharge nozzles; and a support part that supports the housing. The housing includes an opening array surface in which a plurality of nozzle arrays is arrayed, the nozzle arrays being formed by opening parts of the liquid discharge nozzles. The support part fixes the housing in a cleaning posture as a fixation posture when the opening array surface is cleaned. The opening parts are formed such that a positional relationship of the housing in a gravity direction when being fixed in the cleaning posture is such that the opening parts do no overlap each other in the opening array surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection device, a liquid ejection system, and a method for cleaning a liquid ejection device. [Background technology]

[0002] Liquid ejection devices that eject liquid onto a medium are known. Liquid ejection devices include a liquid ejection head that ejects liquid from liquid ejection ports (nozzles). When the liquid ejection head ejects liquid, some of the liquid (residual liquid) may adhere to the nozzle or the area around the nozzle. If this residual liquid is left, the liquid in the nozzle area will dry out and thicken, and as it dries further, it will solidify, which will have an effect on the ejection performance the next time the liquid is ejected. To maintain the ejection performance of the liquid ejection device, a cleaning device is also known that periodically cleans the liquid ejection head to remove residual liquid.

[0003] As a configuration for performing a cleaning process to prevent a deterioration in the liquid ejection characteristics, a configuration has been disclosed that includes a first cleaning unit that wipes the nozzle opening surface by wiping, and a second cleaning unit that can wipe the lower end of the nozzle opening surface in an inclined state, for cleaning when the nozzle opening surface is installed at an angle (see Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0004] When the nozzle opening surface is tilted during cleaning, as in the configuration disclosed in Patent Document 1, the cleaning liquid containing the residual liquid flows along the nozzle opening surface in the direction of gravity, which poses the problem of secondary contamination of the nozzle opening surface due to the flow of the residual liquid.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid ejection device or the like that can improve the ease of cleaning the nozzle opening surface of the liquid ejection head. [Means for solving the problem]

[0006] The present invention, which aims to solve the above-mentioned problems, relates to a liquid ejection device, comprising: a liquid ejection nozzle for ejecting liquid; a housing for holding a plurality of the liquid ejection nozzles; and a support part for supporting the housing, wherein the housing has an opening arrangement surface on which a plurality of nozzle rows each formed by openings of the plurality of the liquid ejection nozzles are arranged, and the support part a multi-axis movable support unit having a plurality of axes, which rotate in different directions around the axes to support the housing with multiple axes, fixing the housing in a cleaning posture as a fixed posture when cleaning the opening arrangement surface; When cleaning the aperture arrangement surface, the aperture arrangement surface is maintained in the cleaning position; The openings are formed so that they do not overlap with each other on the opening arrangement surface when the housing is fixed in the cleaning posture in the direction of gravity. [Effects of the Invention]

[0007] According to the present invention, it is possible to improve the cleaning performance of the nozzle opening surface of the liquid ejection head. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view of a liquid ejection system and a liquid ejection device according to an embodiment of the present invention. [Figure 2] 1A is a perspective view of a liquid ejection head according to an embodiment of the present invention, and FIG. 1B is a partial cross-sectional view thereof. [Figure 3] FIG. 1 is a detailed perspective view of a liquid ejection head according to an embodiment of the present invention. [Figure 4] 1 is an overall cross-sectional view of a liquid ejection head according to an embodiment of the present invention. [Figure 5] 3A to 3C are diagrams illustrating the operating principle of the liquid ejection head. [Figure 6] 3A to 3C are diagrams illustrating the operating principle of the liquid ejection head. [Figure 7] 5A and 5B are diagrams showing examples of stains around nozzle openings in the liquid ejection head. [Figure 8] 10A and 10B are diagrams showing another example of dirt around the nozzle opening of the liquid ejection head. [Figure 9] 10A and 10B are diagrams showing another example of dirt around the nozzle opening of the liquid ejection head. [Figure 10]1 is a perspective view showing an example of a cleaning device according to an embodiment of the present invention; [Figure 11] FIG. 1 is a diagram showing an internal configuration of a cleaning device according to an embodiment of the present invention. [Figure 12] 5A to 5C are diagrams illustrating the operation of the cleaning device according to the embodiment of the present invention. [Figure 13] 5A to 5C are diagrams illustrating the operation of the cleaning device according to the embodiment of the present invention. [Figure 14] FIG. 2 is a diagram illustrating an air supply configuration of the cleaning device according to the embodiment of the present invention. [Figure 15] 5A and 5B are diagrams illustrating a fixed state during cleaning of a liquid ejection head according to an embodiment of the present invention. [Figure 16] 5A and 5B are diagrams illustrating secondary stains that occur when the liquid ejection head is cleaned. [Figure 17] FIG. 2 is a diagram showing an example of a nozzle arrangement of a liquid ejection head according to an embodiment of the present invention. [Figure 18] 5A and 5B are diagrams for explaining the effects obtained by the nozzle arrangement of the liquid ejection head according to the embodiment of the present invention. [Figure 19] FIG. 10 is a diagram showing another example of the nozzle arrangement of the liquid ejection head according to the embodiment of the present invention. [Figure 20] FIG. 10 is a perspective view showing another example of a cleaning device according to an embodiment of the present invention. [Figure 21] 5A and 5B are diagrams for explaining the effects obtained by the nozzle arrangement of the liquid ejection head according to the embodiment of the present invention. [Figure 22] 5A and 5B are diagrams illustrating accumulation positions of secondary dirt that occurs when the liquid ejection head is normal. [Figure 23] 5A and 5B are diagrams illustrating accumulation positions of secondary dirt that occurs when the liquid ejection head is normal. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of a liquid ejection device and a cleaning device for a liquid ejection device according to the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram showing an overall view of an embodiment of a liquid ejection system according to the present invention. As shown in Fig. 1, the liquid ejection system 1 according to this embodiment includes an inkjet head 100, a head transport robot 190, and a cleaning station 200.

[0010] In the following description, the term "direction" may be used to describe the orientation of each component. The definition of this direction will be explained below. As shown in FIG. 1, two orthogonal axes (X-axis and Y-axis) constituting a horizontal plane are assumed, along with a Z-axis that is orthogonal to both of these axes. In this case, since the medium 2 is positioned in the direction of the Y-axis (Y direction) relative to the inkjet head 100, the direction in which the inkjet head 100 ejects liquid ink corresponds to the Y-direction. Furthermore, with respect to the head transport robot 190 that supports the inkjet head 100, the cleaning station 200 is disposed in the direction of the X-axis (X-direction). Therefore, as will be described later, when the inkjet head 100 is cleaned, the orientation of the inkjet head 100 corresponds to the X-direction. Furthermore, when the liquid ejection system 1 is installed on the XY plane, the height direction corresponds to the Z-axis direction (Z-direction). If the direction of each arrow in FIG. 1 is defined as the positive direction, the direction of gravity corresponds to the -Z direction.

[0011] [Overview of an embodiment of a liquid ejection system] The liquid ejection system 1 ejects liquid ink or the like onto a medium 2, and is also used for image formation processes such as painting the surface of the medium 2 and forming an image. The medium 2 may be a three-dimensional object or a flat object, but may also be a three-dimensional object such as a vehicle.

[0012] The inkjet head 100 according to this embodiment is one example of an embodiment of a liquid ejection head according to the present invention, and includes an ejection mechanism that ejects liquid ink onto the medium 2. The ejection mechanism of the inkjet head 100 will be described in detail below.

[0013] The head transport robot 190 has a support unit that supports the inkjet head 100 and has multiple axes. The rotation direction around each axis is a different direction. Therefore, the head transport robot 190 corresponds to a multi-axis movable support unit that can freely move the inkjet head 100 in three-dimensional space (XYZ space) and hold it in a predetermined state by combining the rotation of each axis. In other words, the ejection direction of liquid ink from the inkjet head 100 is changed three-dimensionally by the support of the head transport robot 190. The head transport robot 190 is, for example, a six-axis robot that can support the posture of the inkjet head 100 so that when liquid ink is ejected onto the three-dimensional surface of the medium 2, which is a three-dimensional object, the ejection direction of the liquid ink is directed in a predetermined direction toward the three-dimensional surface.

[0014] The cleaning station 200 is a cleaning device that performs a cleaning process to clean off residual liquid that adheres to the periphery of the ejection ports (nozzles 102) when the inkjet head 100 ejects liquid ink. The cleaning station 200 sprays cleaning liquid 4 toward the nozzles 102 to wash away the residual liquid, and has the function of blowing gas to wipe off the cleaning liquid 4 that has adhered to the nozzles 102 during cleaning. Details of the cleaning station 200 will be described later.

[0015] The liquid ejection system 1 includes a control unit that controls the ejection operation of the inkjet head 100, the operation of the head transport robot 190, and the operation of the cleaning station 200. Note that a detailed description of the control unit included in the liquid ejection system 1 will be omitted.

[0016] The cleaning process in the liquid ejection system 1 is performed on the nozzle plate 101 of the inkjet head 100 when the ejection operation of the inkjet head 100 is completed, or when the number of uses of the ejection operation or the cumulative operation time has passed a predetermined threshold. When this cleaning process is performed, the head transport robot 190, under the control of the control unit, moves the position of the nozzle plate 101 of the inkjet head 100 to a predetermined position relative to the cleaning station 200. Then, the cleaning process is performed with the nozzle plate 101 of the inkjet head 100 fixed at the moved position.

[0017] [Outline of an embodiment of a liquid ejection device] Here, an embodiment of a liquid ejection device according to the present invention will be described. A liquid ejection device 10 according to this embodiment is configured to include at least an inkjet head 100 as an embodiment of a liquid ejection head, and a head transport robot 190 that moves the inkjet head 100 to a predetermined position relative to a cleaning station 200 and fixes it there.

[0018] As will be described later, the liquid ejection device 10 is characterized in that the nozzles 102 of the inkjet head 100 are formed so that the arrangement of the nozzles 102 is in a specific arrangement when the nozzle plate 101 and the nozzles 102 of the inkjet head 100 are cleaned. In other words, the liquid ejection device 10 is provided with a nozzle plate 101 that is formed so that the nozzles 102 are in a specific arrangement when the inkjet head 100 is cleaned.

[0019] [Outline of the embodiment of the liquid ejection head] Next, the configuration of an inkjet head 100 as an embodiment of a liquid ejection head will be described with reference to FIG. 2. FIG. 2 is a diagram illustrating the inkjet head 100 in the state shown in FIG. 1. FIG. 2(a) is a perspective view schematically illustrating the inkjet head 100. FIG. 2(b) is a partial cross-sectional view of a housing 110 of the inkjet head 100. As shown in FIGS. 2(a) and 2(b), the inkjet head 100 includes at least a nozzle plate 101 corresponding to a part of the housing 110, a plurality of nozzles 102 formed in the nozzle plate 101, and a needle valve 131 that operates to eject liquid ink from one nozzle 102. The needle valve 131 is held by the housing 110, which serves as a nozzle holder. The housing 110 holds a liquid ejection mechanism including the needle valve 131 so that the ejection direction of the liquid ink ejected by the needle valve 131 is the direction of the black arrow in FIG. 2(b). Here, the ejection direction corresponds to the Y direction.

[0020] 2(a) and 2(b), a housing 110 serving as a nozzle holder has a plurality of nozzles 102, and a plurality of nozzle openings 103 serving as openings of the nozzles 102 are arranged on one surface of the housing 110. The surface on which the plurality of nozzle openings 103 are arranged corresponds to the opening arrangement surface. Therefore, the surface of the nozzle plate 101 corresponds to the opening arrangement surface.

[0021] The housing 110 is also provided with an array of nozzles 102 as liquid ejection ports for ejecting liquid ink as droplets using needle valves 131. The nozzles 102 are a nozzle opening surface that constitutes part of the housing 110, and a plurality of nozzles 102 are formed in a nozzle plate 101 that constitutes the nozzle array surface. There is a one-to-one relationship between the nozzles 102 and the needle valves 131, so when a specific needle valve 131 operates, droplets are ejected from the corresponding nozzle 102.

[0022] The nozzles 102 are tiny holes formed in a two-dimensional array in the nozzle plate 101 .

[0023] The detailed structure of the inkjet head 100 will now be described with reference to Figures 3 and 4. Figure 3 is an overall perspective view showing an example of the inkjet head 100.

[0024] The inkjet head 100 mainly comprises a housing 110, a connector 150, a supply port 111, and a recovery port 113. The housing 110 is made of a metal material or a resin material. The connector 150 is a terminal for transmitting electrical signals, and in this embodiment, the connector 150 is provided on the top of the housing 110.

[0025] The supply port 111 and the recovery port 113 are located on the left and right sides of the housing 110. The supply port 111 supplies liquid into the head, and the recovery port 113 discharges the liquid ink from the inkjet head 100.

[0026] Figure 4 is a cross-sectional view taken along line AA in Figure 3. Housing 110 has, at its top, a connector 150 for transmitting electrical signals, and at its bottom, holds a nozzle plate 101 as an opening arrangement surface on which nozzles 102 for ejecting liquid are arranged. Housing 110 also has a flow path 112 that sends liquid from the supply port 111 side, over the nozzle plate 101, to the recovery port 113 side. Here, nozzle plate 101 is an example of a "nozzle member."

[0027] Between the supply port 111 and the recovery port 113, a liquid ejection module 130 is arranged as a liquid ejection nozzle for ejecting the liquid ink in the flow path 112 from the nozzle 102. The number of liquid ejection modules 130 corresponds to the number of nozzles 102, and Fig. 4 shows a configuration including eight liquid ejection modules 130 corresponding to the eight nozzles 102 arranged in a row.

[0028] It should be noted that the number and arrangement of the nozzles 102 and liquid ejection modules 130 are not limited to those described above. For example, the number of nozzles 102 and liquid ejection modules 130 may be nine or more, or may be one instead of multiple. Furthermore, the nozzles 102 and liquid ejection modules 130 may be arranged in multiple rows instead of a single row.

[0029] With the above configuration, the supply port 111 takes in pressurized liquid ink from the outside, sends the liquid ink in the direction of arrow a1, and supplies the liquid ink to the flow path 112. The flow path 112 sends the liquid ink from the supply port 111 in the direction of arrow a2. Then, the recovery port 113 discharges the liquid ink that was not ejected from the nozzles 102 arranged along the flow path 112 in the direction of arrow a3.

[0030] The liquid ejection module 130 includes a needle valve 131 that opens and closes the nozzle 102, and a piezoelectric element 132 that drives the needle valve 131. The housing 110 includes a regulating member 134 at a position facing the upper end of the piezoelectric element 132. The regulating member 134 abuts against the upper end of the piezoelectric element 132, and serves as a fixing point for the piezoelectric element 132. Here, the needle valve 131 is an example of an ejection unit that ejects liquid ink, and the piezoelectric element 132 is an example of an actuator.

[0031] [Outline of liquid ink ejection principle] 5 and 6, an outline of the liquid ink ejection operation in the inkjet head 100 will be described. As shown in Fig. 5, when the tip of the needle valve 131 is in close contact with the nozzle 102, the liquid ink is not ejected from the nozzle 102 as pressurized liquid.

[0032] In the above configuration, when the piezoelectric element 132 is actuated and the needle valve 131 is displaced to the right in Fig. 6, the nozzle 102, which was closed by the needle valve 131, opens, and liquid ink is ejected from the nozzle 102 as ejection droplets 3. When the piezoelectric element 132 is actuated and the needle valve 131 is displaced to the left, the state returns to that shown in Fig. 5, so that the tip of the needle valve 131 comes into contact with the nozzle 102 and the nozzle 102 is closed. In other words, liquid is no longer ejected from the nozzle 102.

[0033] The piezoelectric element 132 operates several thousand times per minute, and the needle valve 131 performs a piston action in accordance with the operation cycle, closing and opening the nozzle 102. In accordance with this opening and closing operation of the nozzle 102, liquid ink is ejected drop by drop from the nozzle 102.

[0034] [About dirt on nozzle 102] Next, a description will be given of stains caused by remaining liquid ink (residual liquid) in the inkjet head 100 according to this embodiment. Figures 7, 8 and 9 each show examples of stains around the nozzles 102.

[0035] As shown in FIGS. 7 and 8, when the ejection operation is completed, thickened residual liquid 31, which is thickened liquid, may remain in the nozzles 102 and the nozzle plate 101 serving as the nozzle opening surface.

[0036] Furthermore, as shown in FIG. 9, mist generated during ejection may cause residual liquid to solidify around the nozzles 102 of the nozzle plate 101, resulting in solidified residual liquid 32.

[0037] If there is thickened residual liquid 31 or solidified residual liquid 32 around the nozzle 102 or on the nozzle plate 101, it will cause discharge resistance the next time the ink is discharged. This discharge resistance can cause the ink to bend or, if the viscosity is large, cause ink to fail to be discharged. To maintain the quality of the discharge, it is necessary to remove this thickened residual liquid 31 or solidified residual liquid 32.

[0038] [Cleaning Station 200 Overview] Next, Fig. 10 shows a cleaning station 200 as an embodiment of the cleaning device provided in the liquid ejection system 1. As shown in Fig. 10, the cleaning station 200 is composed of a cleaning station housing 210, a base plate 220, a sealing member 230 as a head holder, and the like.

[0039] The nozzles 102 and the nozzle plate 101 are cleaned in the cleaning station 200. Therefore, when cleaning the inkjet head 100, the head transport robot 190 moves the inkjet head 100 close to the cleaning station 200 and fixes the inkjet head 100 in contact with the cleaning station 200 in a state that will be described later.

[0040] [Internal structure of the Cleaning Station 200] Fig. 11 illustrates the internal structure of the cleaning station 200 serving as the cleaning unit. Fig. 12 illustrates a schematic diagram of the state when cleaning the nozzle plate 101. Fig. 13 illustrates a schematic diagram of the state when the cleaning liquid 4 is removed after the cleaning operation on the nozzle plate 101.

[0041] 11, the cleaning station 200 is equipped with at least a cleaning nozzle 240 as a cleaning liquid spraying unit, an air nozzle 250 as a gas spraying unit, a cleaning liquid supply tube 241 for supplying cleaning liquid 4 to the cleaning nozzle 240, and an air supply tube 251 for supplying gas to the air nozzle 250. The cleaning liquid supply tube 241 and the air supply tube 251 are supported at predetermined positions by a nozzle support rod 260.

[0042] 11 illustrates a state when the inkjet head 100 is being cleaned. That is, during cleaning, the nozzle plate 101 of the inkjet head 100 is fixed in close contact with the sealing member 230. This prevents the cleaning liquid 4 from leaking out of the cleaning station 200.

[0043] During cleaning, the inkjet head 100 is fixed so that the surface of the nozzle plate 101, which serves as the aperture arrangement surface, faces in a direction parallel to the horizontal plane (XY plane) rather than facing the horizontal plane. That is, the inkjet head 100 is fixed so that the aperture arrangement surface is inclined with respect to the horizontal plane. In the example of FIG. 11, the nozzle plate 101 having the aperture arrangement surface is inclined at an angle of 90 degrees with respect to the horizontal plane. That is, when the inkjet head 100 ejects liquid ink while in the cleaning posture, which is the posture during cleaning, the ejection direction of the ejected droplets 3 ejected from each nozzle 102 is not the direction of gravity (-Z direction) but a direction intersecting the direction of gravity (X direction).

[0044] Therefore, when cleaning the inkjet head 100, the cleaning liquid 4 is sprayed onto the nozzle plate 101, which is fixed in a state inclined (for example, vertical) with respect to the horizontal plane. As a result, as will be described later, the cleaning liquid 4 and the thickened residual liquid 31 and solidified residual liquid 32 cleaned by the cleaning liquid 4 flow in the direction of gravity along the surface of the nozzle plate 101.

[0045] 12 illustrates an example of how the nozzle plate 101 and the nozzles 102 are cleaned. As shown in FIG. 12, when cleaning the nozzle plate 101 and the nozzles 102, the housing 110 is moved to the cleaning position, the nozzle plate 101 is brought into contact with the sealing member 230 and fixed, and then the cleaning liquid 4 is sprayed from the cleaning nozzle 240. The cleaning nozzle 240 sprays the cleaning liquid 4 after the inkjet head 100 is fixed in close contact with the sealing member 230 at a predetermined position. Therefore, the control unit provided in the liquid ejection system 1 determines the fixed state of the inkjet head 100 based on a signal from a sensor that detects that the inkjet head 100 has been fixed to the sealing member 230, and controls the start of spraying from the cleaning nozzle 240.

[0046] The spraying of the cleaning liquid 4 from the cleaning nozzle 240 continues until a preset threshold time has elapsed, and is controlled based on a detection signal from a sensor that detects the cleaning state of the inkjet head 100.

[0047] When the cleaning liquid 4 is sprayed onto the nozzle plate 101 , a sealing member 230 seals the gap between the nozzle plate 101 and the base plate 220 to prevent the cleaning liquid 4 from scattering outside the cleaning station 200 .

[0048] Note that by spraying the cleaning liquid 4 onto the nozzle plate 101, it is possible to remove residual liquid adhering to the surface of the nozzle plate 101 and the nozzles 102. However, the cleaning liquid 4 will remain attached to the nozzle plate 101. If ejection onto the medium 2 is resumed while the cleaning liquid 4 remains attached, there is a possibility that the cleaning liquid 4 will adhere to the medium 2, which will have an adverse effect on the state of adhesion of the liquid ink to the medium 2.

[0049] 12, after the cleaning liquid 4 is sprayed onto the nozzle plate 101, cleaning liquid removal air 5 is sprayed from the air nozzle 250. The spray of this cleaning liquid removal air 5 removes the cleaning liquid 4 adhering to the nozzle plate 101. The spray of the cleaning liquid removal air 5 from the air nozzle 250 continues until a preset threshold time has elapsed, or is controlled based on a detection signal from a sensor that detects the remaining state of cleaning liquid 4 in the inkjet head 100. Even when the cleaning liquid removal air 5 is sprayed, the nozzle plate 101 is fixed in a state aligned with the direction of gravity. Therefore, the remaining liquid that has been moved across the nozzle plate 101 by the cleaning liquid removal air 5 flows in the direction of gravity (-Z direction) and is removed.

[0050] [Cleaning fluid and air wiring diagram] Next, we will explain the supply configuration of the cleaning liquid 4 and the supply configuration of the cleaning liquid removal air 5 that enable the spraying operations of the cleaning nozzle 240 and the air nozzle 250 provided in the cleaning station 200. Figure 14 is a diagram schematically showing the supply configuration 270 of the cleaning liquid 4 and the cleaning liquid removal air 5.

[0051] At the location where cleaning station 200 is installed, pressurized gas (air) is supplied from facility air 290, which is an air source for facilities etc. that is already available for use. After the pressure is adjusted by primary regulator 271, the air is branched into two lines by primary joint 272 and supplied.

[0052] One of the air branches by the primary joint 272 is further branched by a secondary joint 273 and separated into air for spraying cleaning liquid and air 5 for removing cleaning liquid.

[0053] The other air branched by the primary joint 272 is conveyed to a solenoid valve 279 and used to control the ON / OFF of the cleaning liquid 4 and the cleaning liquid removal air 5 .

[0054] Of the gases branched by the secondary joint 273, the air for spraying the cleaning liquid 4 is carried to a pressurized tank 275 in order to spray the cleaning liquid 4 at a predetermined pressure. A liquid pressure adjustment regulator 274 is installed immediately before the pressurized tank 275, making it possible to adjust the pressure of the pressurized tank 275. The cleaning liquid 4 is poured into the pressurized tank 275, and the cleaning liquid 4 pressurized to a predetermined pressure in the pressurized tank 275 is carried to the cleaning nozzle 240.

[0055] A cleaning liquid ON / OFF valve 276 is disposed between the cleaning nozzle 240 and the pressure tank 275, and air branched by a solenoid valve 279 is input to the valve. The solenoid valve 279 is controlled by a control PC 280, and it is possible to control the input of air to the cleaning liquid ON / OFF valve 276.

[0056] When it is determined that the housing 110 has moved to the cleaning station 200 and is fixed, the air from the solenoid valve 279 to the cleaning liquid ON / OFF valve 276 is turned ON, and the cleaning liquid 4 is sprayed from the cleaning nozzle 240 toward the nozzle plate 101. After a predetermined time has elapsed, the air from the solenoid valve 279 to the cleaning liquid ON / OFF valve 276 is turned OFF, and spraying of the cleaning liquid 4 ends.

[0057] Of the air branched by the secondary joint 273, the air for spraying the cleaning liquid removal air 5 is conveyed to the air nozzle 250 via an air pressure adjustment regulator 278 for adjusting the air pressure to the required level and an air ON / OFF valve 277. Air branched by a solenoid valve 279 is input to the air ON / OFF valve 277, and by controlling the solenoid valve 279 with a control PC 280, it is possible to control the input of air to the air ON / OFF valve 277.

[0058] When the spraying of the cleaning liquid 4 onto the nozzle plate 101 has finished and the air from the solenoid valve 279 to the cleaning liquid ON / OFF valve 276 has been turned off, the air is turned on to the air ON / OFF valve 277, and cleaning liquid removal air 5 is sprayed from the air nozzle 250. After a predetermined time has elapsed, the air from the solenoid valve 279 to the air ON / OFF valve 277 is turned off, and the spraying of the cleaning liquid removal air 5 has finished.

[0059] [Conventional issues when cleaning the inkjet head 100] Here, the problems that arise when cleaning the inkjet head 100 using the cleaning station 200 will be explained with reference to the drawings.

[0060] FIG. 15 is a view showing a state in which the housing 110 of the inkjet head 100 is fixed to a sealing member 230 fixed to the cleaning station 200, as viewed from the opening side of the nozzles 102. In the example of FIG. 15, the nozzles 102 are arranged in a vertical array of three, each arranged at a predetermined interval in the longitudinal direction. This arrangement of the nozzles 102 is maintained by the housing 110. Therefore, depending on the state in which the housing 110 is fixed to the cleaning station 200, the vertical and horizontal directions in the drawing may differ. However, in the description herein, the up-down direction (Z direction) when facing the drawing head is referred to as the vertical direction of the inkjet head 100, and the left-right direction (X direction) is referred to as the horizontal direction of the inkjet head. The vertical direction of the inkjet head 100 shown in FIG. 15 will be described as the direction of gravity.

[0061] In other words, as shown in FIG. 15 , the inkjet head 100 has a nozzle plate 101 that is rectangular in shape in a plan view, and a plurality of nozzles 102 formed in a planar manner on the nozzle plate 101. The surface (aperture arrangement surface) of the nozzle plate 101 on which the nozzles 102 are formed is outlined by four sides. The nozzles 102 are formed at predetermined intervals along two opposing long sides (longitudinal directions) of the four sides. The plurality of nozzles 102 formed along the longitudinal direction are referred to as nozzle rows, and the plurality of nozzle rows are arranged in the lateral direction of the nozzle plate 101. That is, the aperture arrangement surface, which is the surface of the nozzle plate 101, has a plurality of nozzle rows, each of which has a plurality of nozzles 102 arranged therein. Note that each nozzle row is formed at a predetermined interval in the lateral direction of the nozzle plate 101. As described above, when the inkjet head 100 is fixed to the cleaning station 200, the inkjet head 100 has a plurality of nozzles 102 on the aperture arrangement surface that are arranged along the direction of gravity.

[0062] Assume that the nozzles 102 are cleaned when the nozzles 102 are arranged as shown in Fig. 15, that is, when the nozzles 102 are arranged as shown in Fig. 15 when the housing 110 is fixed to the sealing member 230. In this case, the sprayed cleaning liquid 4 flows in the direction of gravity (-Z direction) like the post-cleaning residual liquid 30 shown in Fig. 16. At this time, the thickened residual liquid 31 and solidified residual liquid 32 washed off by the cleaning liquid 4 also flow in the direction of gravity along the surface of the nozzle plate 101 together with the post-cleaning residual liquid 30.

[0063] When the post-cleaning residual liquid 30 flows in the state illustrated in FIG. 16 , the post-cleaning residual liquid 30 washed away from the nozzle 102 at the uppermost position in the direction of gravity flows toward the nozzle 102 at the middle position. Furthermore, the post-cleaning residual liquid 30 washed away from the middle position in the direction of gravity flows toward the nozzle 102 at the lowermost position together with the post-cleaning residual liquid 30 from the uppermost position. In this way, since the post-cleaning residual liquid 30 flows from top to bottom in the direction of gravity, the lower the nozzle 102 is located, the higher the possibility of secondary contamination by the post-cleaning residual liquid 30 flowing from the upper position. Furthermore, the cleaning effect of the cleaning liquid 4 on the nozzle 102 at the lowermost position and the surface of the nozzle plate 101 in the vicinity thereof is reduced, increasing the possibility of thickened residual liquid 31 or solidified residual liquid 32 remaining unwashed.

[0064] Furthermore, post-cleaning residual liquid 30 that is not blown away by the spraying of cleaning liquid removal air 5 and remains on the surface of nozzle plate 101 also moves in the direction of gravity, as described above, and may re-adhere to the nozzle 102, which is at the lowest position. If it is dried in this state, the thickened residual liquid 31 or solidified residual liquid 32 will again remain on the surface of nozzle plate 101 and nozzle opening 103, which may cause problems such as deflected ejection or non-ejection.

[0065] [First embodiment] Next, a first embodiment of a liquid ejection head provided in a liquid ejection device according to the present invention will be described. The inkjet head 100 according to this embodiment solves the problems described above, maintains the ejection performance of the inkjet head 100, and prevents problems such as deflected ejection and ejection failure.

[0066] The inkjet head 100 according to this embodiment is configured so that, when fixed for cleaning, the multiple nozzles 102 held in the housing 110 are positioned so that at least adjacent nozzles 102 in the direction of gravity do not overlap with each other in the direction of gravity. For example, as shown in Fig. 17, among the nozzles 102 on the surface (aperture arrangement surface) of the nozzle plate 101, the nozzle 102 formed at the uppermost position in the direction of gravity and the nozzle 102 formed at the lowermost position are positioned so that they do not overlap with each other in the direction of gravity. Furthermore, the nozzles 102 formed at the middle positions are positioned so that they do not overlap with the nozzles 102 formed at the uppermost position in the direction of gravity, and also do not overlap with the nozzles 102 formed at the lowermost position in the direction of gravity.

[0067] When the inkjet head 100 is fixed to the cleaning station 200 during cleaning, the nozzle plate 101 is fixed with the nozzle plate 101 facing horizontally. That is, the nozzles 102 (nozzle openings 103) are formed in the nozzle plate 101 so that when the nozzle plate 101 is fixed in an orientation perpendicular to the horizontal plane (an example of an inclination), the positional relationship of the nozzles 102 (nozzle openings 103) that are adjacent to each other in the direction of gravity is such that they do not overlap each other in the direction along the direction of gravity.

[0068] In other words, the nozzles 102 are formed on the nozzle plate 101 so that the relative positional relationship between the multiple nozzles 102 in their arrangement is established when the nozzle plate 101 is fixed in a tight contact state to the sealing member 230 by the head transport robot 190.

[0069] Fig. 18 shows an example of a state when a cleaning process is performed on the inkjet head 100 according to this embodiment shown in Fig. 17. As shown in Fig. 18, the nozzles 102 are positioned so that they do not overlap in the direction of gravity, and therefore the post-cleaning residual liquid 30 flows from the upper position to the lower position, which reduces the possibility that the post-cleaning residual liquid 30 flowing from the upper position will flow into the nozzle 102 in the middle position, and further reduces the possibility that the post-cleaning residual liquid 30 from the upper and middle positions will flow into the nozzle 102 in the lower position.

[0070] Furthermore, even when a small amount of post-cleaning residual liquid 30 remaining after the spraying of the cleaning liquid removal air 5 flows downward in the direction of gravity, the possibility of the post-cleaning residual liquid 30 re-adhering to the nozzles 102 formed in the downward position can be reduced. Therefore, even if the post-cleaning residual liquid 30 remains on the nozzle plate 101 and dries, it is possible to prevent the nozzles 102 and the vicinity of the nozzles 102 from becoming thickened residual liquid 31 or solidified residual liquid 32. In other words, it is possible to reduce the possibility of problems such as deflected ejection or non-ejection due to secondary contamination.

[0071] The inkjet head 100 is an embodiment of a liquid ejection head capable of ejecting liquid in multiple directions including the direction of gravity, and the ejection direction of the ejected droplets 3 from the inkjet head 100 is controlled by a head transport robot 190. That is, the cleaning process is also performed in a state where the inkjet head 100 is supported by the head transport robot 190 and fixed in a predetermined posture. When performing this cleaning process, the nozzles 102 are formed and used so that the positional relationship of the array of the nozzles 102 does not overlap with each other in the direction of gravity.

[0072] That is, the inkjet head 100 according to this embodiment can effectively prevent problems (such as deflected ejection or ejection failure) that can occur when the ejection direction of the ejected droplets 3 is not the direction of gravity. That is, this embodiment can solve problems that can occur when the inkjet head 100 is positioned during cleaning such that the ejection direction of the ejected droplets 3 is not the direction of gravity, but is, for example, perpendicular to the direction of gravity.

[0073] [Modification of the first embodiment] As shown in FIG. 19, the number of nozzles 102 arranged in the direction of gravity (the number of nozzle rows) may be greater than the number illustrated in FIG. 17. In FIG. 17, the needle valves 131 held by the housing 110 of the inkjet head 100 are arranged in three rows in the direction of gravity, so three nozzle rows are formed in the direction of gravity. In this regard, in order to improve the productivity of the process of ejecting liquid to form an image and to improve coating quality, the number of nozzles 102 held by the inkjet head 100 (the number of nozzle rows) may be increased from the example illustrated in FIG. 17. In this case, three or more nozzle rows are arranged in the direction of gravity on the surface (opening arrangement surface) of the nozzle plate 101 that forms the housing 110. In other words, the number of needle valves 131 arranged in the direction of gravity is increased.

[0074] As shown in the example of FIG. 17, even if the nozzles 102 are formed at positions where they do not overlap each other in the direction of gravity when the housing 110 is fixed to the cleaning station 200, if the number of nozzles 102 formed in the nozzle plate 101 is increased, there is a possibility that the positional relationship in the direction of gravity will become a state where the nozzles 102 partially overlap. An example of this is shown in FIG. 19. If the number of nozzles 102 arranged is increased two-dimensionally, the positional relationship in the direction of gravity of the nozzles 102 in the fixed state during cleaning may become a positional relationship where the nozzles 102 overlap at the uppermost and lowermost positions. Furthermore, if more nozzles 102 are formed than in the example of FIG. 19, it is conceivable that the number of nozzles 102 overlapping in the direction of gravity will increase in the positional relationship in the fixed state during cleaning.

[0075] Therefore, at least among the relative positions of the nozzles 102 in the direction of gravity, the nozzles 102 formed in the uppermost position and the nozzles 102 formed in the lowermost position are allowed to overlap, and the other relative positions are formed so that they do not overlap in the direction of gravity. That is, as shown in Fig. 19, when the nozzles 102 overlap in the direction of gravity, the distance between the nozzles is set as far as possible. This can reduce the possibility of secondary contamination occurring.

[0076] 19, the nozzles 102 corresponding to the uppermost position among the positions formed on the nozzle plate 101 are positioned so as to overlap with the nozzles 102 corresponding to the lowermost position in the direction of gravity. On the other hand, the other nozzles 102 are positioned so as not to overlap with each other in the direction of gravity.

[0077] [Second embodiment] Next, a second embodiment of the liquid ejection device according to the present invention will be described. In the first embodiment, when the housing 110 is fixed to the cleaning station 200, the nozzles 102 are arranged so that they do not overlap with each other in terms of their relative positional relationship in the direction of gravity.

[0078] In the second embodiment, as shown in FIG. 20, a base plate 220a and a sealing member 230a included in a cleaning station 200a are inclined relative to the horizontal plane so that the housing 110 of the inkjet head 100 itself is fixed in an inclined position during cleaning.

[0079] During cleaning, the nozzle plate 101 of the inkjet head 100 is tightly attached to the sealing member 230a and fixed so that the cleaning liquid 4 does not leak out of the cleaning station 200a. In this fixed state, the nozzle plate 101 is fixed with its longitudinal direction tilted relative to the horizontal plane. This tilt relative to the horizontal direction is at a predetermined tilt angle θ, which is determined by the base plate 220a and the sealing member 230a provided on the cleaning station housing 210a. This makes it possible to create a state in which none of the nozzles 102 overlap in the direction of gravity during cleaning.

[0080] Figure 21 is a diagram showing an example of the fixed posture of the inkjet head 100 held in the cleaning station 200a according to this embodiment during cleaning. When cleaning the inkjet head 100 using the cleaning station 200a, the portion where the inkjet head 100 is fixed is inclined at an inclination angle θ with respect to the horizontal plane. Therefore, as shown in Figure 21, of the sides that form the outline of the nozzle plate 101 of the housing 110, the longitudinal side is inclined at an inclination angle θ with respect to the horizontal plane, and the inkjet head 100 is fixed to the cleaning station 200 in this state.

[0081] 1, the inkjet head 100 including the housing 110 is supported by supports that are rotatable in the axial directions of multiple shafts provided in the head transport robot 190. Therefore, the orientation of the inkjet head 100 can be freely changed in accordance with the rotation of the movable shafts. Therefore, when the inkjet head 100 is fixed to the cleaning station 200a, it can be maintained in an orientation in which the longitudinal direction of the housing 110 is tilted at an angle θ with respect to the horizontal plane.

[0082] That is, according to the inkjet head 100 according to the second embodiment, the orientation of the housing 110 serving as a nozzle holder when fixed to the cleaning station 200a is maintained in a state inclined at an inclination angle θ. Due to this inclined state, even if the nozzles 102 overlap with each other in the direction of gravity when the longitudinal direction of the housing 110 is parallel to the horizontal plane (see FIG. 15), the nozzles 102 can be prevented from overlapping with each other in the direction of gravity during cleaning.

[0083] 21, the nozzle plate 101 is fixed and cleaned with its longitudinal sides forming an inclination angle θ with respect to the horizontal plane, which reduces the possibility that residual liquid 30 remaining after cleaning that occurs when cleaning upper nozzles 102 flows to lower nozzles 102. As a result, it is possible to reduce the risk of incomplete cleaning.

[0084] Furthermore, if a small amount of cleaning liquid droplets remain after the cleaning liquid removal air 5 is sprayed, they move downward in the direction of gravity, but since the nozzle 102 is not present in the direction of gravity, secondary contamination can be prevented and cleaning performance is improved.

[0085] As explained in the first embodiment, in the second embodiment, when the number of nozzles 102 increases, it becomes difficult to prevent the nozzles 102 from overlapping in the direction of gravity. In this case, the tilt angle θ when fixing the inkjet head 100 to the cleaning station 200 is adjusted by the head transport robot 190. This adjustment is made to an angle that maximizes the distance between the nozzles 102 when they overlap in the direction of gravity, thereby reducing the possibility of secondary contamination.

[0086] Figures 22 and 23 illustrate the difference in the locations where residual liquid 30 is likely to accumulate after cleaning when the inkjet head 100 is fixed to the cleaning station 200 and the sides of the nozzle plate 101 are in a position parallel to the horizontal plane and when the sides form an inclination angle θ.

[0087] 22, when the housing 110 of the inkjet head 100 is fixed to the cleaning station 200 (during cleaning), if the nozzle plate 101 is fixed so that its longitudinal direction is parallel to the horizontal plane, the post-cleaning residual liquid 30 remains at the lower end of the sealing member 230. In FIGS. 22 and 23, the remaining position 35 of the post-cleaning residual liquid 30 is shown by a dashed circle.

[0088] On the other hand, as shown in FIG. 23, when the nozzle plate 101 is fixed with its longitudinal direction inclined at an angle θ with respect to the horizontal plane, the post-cleaning residual liquid 30 remains at the corners of the sealing member 230 .

[0089] If cleaning liquid 4 or post-cleaning residual liquid 30 remains on the nozzle plate 101, it can cause ejection defects, so it is necessary to remove as much of the post-cleaning residual liquid 30 remaining on the nozzle plate 101 as possible. In this case, when the nozzle plate 101 is fixed so that its longitudinal direction is parallel to the horizontal plane, as in the example of Figure 22, attention must be paid to a wide range over the entire lower end of the sealing member 230. However, when the nozzle plate 101 is fixed in an orientation that forms an inclination angle θ, as shown in the example of Figure 23, attention must be paid only to the corners of the sealing member 230, making it easier to remove the post-cleaning residual liquid 30 from the nozzle plate 101.

[0090] [others] In the cleaning methods for the inkjet head 100 according to the first and second embodiments described above, the cleaning liquid 4 is sprayed onto the nozzles 102 and the nozzle plate 101. However, cleaning methods that can be applied to the liquid ejection device according to the present invention are not limited to this.

[0091] For example, a similar effect can be obtained with a wiping method using a wiper member. However, even when the wiping method is applied, as described above, in order to efficiently clean the nozzles 102 and the nozzle plate 101, it is necessary to apply the cleaning liquid 4, and therefore, after wiping the nozzle plate 101, the post-cleaning residual liquid 30 may drip in the direction of gravity.

[0092] As explained in the first and second embodiments, when fixing the nozzle holder to the cleaning station 200, by controlling the nozzle 102 so that it does not overlap in the direction of gravity, it is possible to reduce the risk of secondary contamination even in the wiper wiping method, and to improve cleaning performance.

[0093] The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the technical gist thereof. The present invention covers all technical matters included in the technical ideas described in the claims. The above-described embodiments are preferred examples, but a person skilled in the art can realize various modifications from the disclosed contents. Such modifications are also included in the technical scope described in the claims. [Explanation of symbols]

[0094] 1: Liquid dispensing system 10:Liquid discharge device 100: Inkjet head 101: Nozzle plate 102: Nozzle 110: Housing 131: Needle valve 190: Head transport robot 200: Cleaning Station 210: Cleaning station housing 220: Base plate 230: Sealing member 280: Control PC [Prior art documents] [Patent documents]

[0095] [Patent Document 1] Japanese Patent Application Publication No. 2020-189446

Claims

1. a liquid discharge nozzle that discharges a liquid; a housing for holding a plurality of the liquid discharge nozzles; a support portion that supports the housing, the housing has an opening arrangement surface on which a plurality of nozzle rows each formed by openings of the plurality of liquid ejection nozzles are arranged, The support portion is a multi-axis movable support unit having a plurality of axes and rotating in different directions around the axes to support the housing on multiple axes, the multi-axis movable support unit fixing the housing in a cleaning posture as a fixed posture when cleaning the opening arrangement surface, and holding the posture of the opening arrangement surface in the cleaning posture when cleaning the opening arrangement surface; The liquid ejection device according to claim 1, wherein the openings are formed so as not to overlap with each other on the opening arrangement surface in terms of their positional relationship in the direction of gravity of the housing when fixed in the cleaning posture.

2. The cleaning posture is a posture in which the opening arrangement surface is inclined with respect to a horizontal plane, The liquid ejection device according to claim 1 , wherein the openings are formed in a positional relationship such that adjacent positions in the direction of gravity do not overlap on the opening arrangement surface in the cleaning posture.

3. The cleaning posture is a posture in which the opening arrangement surface is inclined with respect to a horizontal plane, 2. The liquid ejection device according to claim 1, wherein the openings are formed such that, on the opening arrangement surface in the cleaning posture, the openings corresponding to the uppermost position in the direction of gravity and the openings corresponding to the lowermost position do not overlap with each other in the direction of gravity, and adjacent openings do not overlap with each other in the direction of gravity.

4. a liquid discharge nozzle that discharges a liquid; a housing for holding a plurality of the liquid discharge nozzles; a support portion that supports the housing, the housing has an opening arrangement surface on which a plurality of nozzle rows each formed by openings of the plurality of liquid ejection nozzles are arranged, the support portion fixes the housing in a cleaning posture that is a fixed posture when cleaning the opening arrangement surface; The liquid ejection device is characterized in that the positional relationship of the openings when fixed in the cleaning posture is such that, among the multiple nozzle rows that form the opening arrangement surface, the positional relationship of the openings that constitute the nozzle row corresponding to the uppermost position and the positional relationship of the openings that constitute the nozzle row corresponding to the lowermost position overlap in the direction of gravity, and the positional relationships of the openings that constitute the other nozzle rows are such that they do not overlap in the direction of gravity.

5. The cleaning posture is a posture in which the opening arrangement surface is inclined with respect to a horizontal plane, and the sides constituting the outline of the opening arrangement surface are also inclined with respect to the horizontal plane, The liquid ejection device according to claim 1 , wherein the openings are formed so as not to overlap with each other on the opening arrangement surface when the housing is fixed in the cleaning posture in the direction of gravity.

6. the support portion is a multi-axis movable support portion having a plurality of axes and rotating in different directions around the axes to support the housing with multiple axes, The liquid ejection device according to claim 4 or 5, wherein the multiaxial movable support member rotates and fixes the housing in an axial direction perpendicular to the aperture arrangement surface when the aperture arrangement surface is cleaned.

7. A liquid ejection system including a liquid ejection device having a liquid ejection head and a cleaning device that cleans the liquid ejection head, The liquid ejection device a liquid discharge nozzle that discharges a liquid; a housing that holds the plurality of liquid ejection nozzles and has an opening arrangement surface on which a plurality of nozzle rows each formed by openings of the plurality of liquid ejection nozzles are arranged; a support portion that fixes the housing in a cleaning posture as a fixed posture when cleaning the opening arrangement surface, The cleaning device is a cleaning unit that cleans the openings and the opening arrangement surface; a head holding part that holds the housing in a cleaning position as a fixed position during cleaning by the cleaning part, the openings are formed so that the positional relationship of the housing in the direction of gravity when the housing is fixed in the cleaning posture does not overlap with each other on the opening arrangement surface, The cleaning unit includes: a cleaning liquid jetting unit capable of jetting a cleaning liquid for cleaning the openings and the opening arrangement surface; a gas ejection unit capable of ejecting gas onto the openings and the opening arrangement surface.

8. A method for cleaning a liquid ejection device having a plurality of liquid ejection nozzles that eject liquid, comprising: a multi-axis movable support part having a plurality of axes, which rotates in different directions around the axes to support a housing having an opening arrangement surface on which a plurality of nozzle rows each formed by openings of the plurality of liquid ejection nozzles are arranged; the multi-axis movable support unit rotates to move the opening arrangement surface to a cleaning position; When cleaning the aperture arrangement surface, the aperture arrangement surface is fixed in an inclined position relative to a horizontal plane, The orientation of the aperture arrangement surface is maintained in a cleaning orientation; After the positional relationship of the openings in the gravity direction is such that they do not overlap on the opening arrangement surface, a cleaning liquid is sprayed onto the openings and the opening arrangement surface to clean them; A method for cleaning a liquid ejection device, comprising spraying gas onto the openings and the opening arrangement surface.

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