Liquid jetting device and cleaning method for liquid ejection head

Abstract

To properly discharge air bubbles from a head in a liquid jetting device including circulation mechanism.SOLUTION: A liquid jetting device 100 comprises: one or more liquid jetting heads 10 each of which has a filter 116 provided in the middle of a flow path supplying liquid to a plurality of nozzles N jetting liquid; a liquid storage unit 93 storing liquid which is supplied to the liquid jetting head 10; a circulation mechanism 94 which circulates the liquid between the liquid jetting head 10 and the liquid storage unit 93; and a control unit 90 which controls the circulation mechanism 94. The one or each of the more liquid jetting heads 10 includes a first liquid jetting head 10_1 which has a first filter as the filter 116. The control unit 90 performs the first circulation cleaning processing which performs the second circulation operation of circulating the liquid at a second flow rate greater than a first flow rate after performing the first circulation operation of circulating the liquid at a first flow rate with respect to the first liquid jetting head 10_1.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a liquid ejecting apparatus and a method for cleaning a liquid ejecting head. [Background technology]

[0002] Patent document 1 discloses a liquid ejection device that includes a liquid ejection head in which a filter for filtering liquid is provided midway through a flow path that supplies liquid to multiple nozzles that eject the liquid, and a liquid storage section that stores the liquid to be supplied to the liquid ejection head. The liquid ejection device circulates the liquid between the liquid ejection head and the liquid storage section, thereby discharging air bubbles within the flow passages of the liquid ejection head to the outside of the liquid ejection head. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-194881 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, with conventional technology, even when liquid was circulated between the liquid ejection head and the liquid storage section, there was a risk of air bubbles remaining in the upstream chamber located upstream of the filter in the filter chamber in which the filter is located. [Means for solving the problem]

[0005] In order to solve the above problems, a liquid ejection device according to a preferred embodiment of the present invention comprises one or more liquid ejection heads having a filter provided in the middle of a flow path that supplies liquid to a plurality of nozzles that eject the liquid, a liquid storage section that stores liquid to be supplied to the liquid ejection heads, a circulation mechanism that circulates liquid between the liquid ejection heads and the liquid storage section, and a control section that controls the circulation mechanism, wherein the one or more liquid ejection heads include a first liquid ejection head having a first filter as the filter, and the control section performs a first circulation cleaning process on the first liquid ejection head, which performs a first circulation operation to circulate liquid at a first flow rate, and then a second circulation operation to circulate liquid at a second flow rate that is greater than the first flow rate.

[0006] Furthermore, a preferred embodiment of a method for cleaning a liquid jet head according to the present invention is a method for cleaning a first liquid jet head having a first filter provided in the middle of a flow path that supplies liquid to a plurality of nozzles that eject the liquid supplied from a first liquid storage section, and is characterized in that a first circulation cleaning process is performed on the first liquid jet head, which performs a first circulation operation to circulate liquid between the first liquid jet head and the first liquid storage section at a first flow rate, and then a second circulation operation to circulate the liquid at a second flow rate greater than the first flow rate. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic diagram showing an example of the configuration of a liquid ejecting apparatus 100 according to a first embodiment. [Diagram 2] FIG. 2 is a diagram of the liquid ejection device 100 viewed in the x1 direction. [Diagram 3] FIG. [Figure 4] FIG. [Diagram 5] Cross-sectional view taken along line AA in Figure 4. [Figure 6] FIG. [Figure 7]FIG. 13 is a diagram showing the state around the filter 116 during printing when the arrangement angle θ is 45 degrees. [Figure 8] FIG. 13 is a diagram showing the state near the filter 116 during the circulation cleaning operation when the arrangement angle θ is 45 degrees. [Figure 9] FIG. 13 is a diagram showing a state near the filter 116 after a circulation cleaning operation when the arrangement angle θ is 45 degrees. [Figure 10] FIG. 13 is a diagram showing the state near the filter 116 when the arrangement angle θ is 45 degrees and during the first circulation cleaning operation. [Figure 11] FIG. 13 is a diagram showing the state near the filter 116 when the arrangement angle θ is 45 degrees and the second circulation cleaning operation is being performed. [Figure 12] FIG. 13 is a diagram showing a state near the filter 116 after the second circulation cleaning operation when the arrangement angle θ is 45 degrees. [Figure 13] 13 is a diagram showing a state near the filter 116 when the arrangement angle θ is 0 degrees and at a stage prior to the first circulation cleaning operation. FIG. [Figure 14] FIG. 13 is a diagram showing a state near the filter 116 when the arrangement angle θ is 0 degrees and during the first circulation cleaning operation. [Figure 15] FIG. 13 is a diagram showing a state near the filter 116 when the arrangement angle θ is 0 degrees and during the second circulation cleaning operation. [Figure 16] FIG. 13 is a diagram showing the state near the filter 116 when the arrangement angle θ is 30 degrees and at a stage prior to the first circulation cleaning operation. [Figure 17] FIG. 13 is a diagram showing the state near the filter 116 when the arrangement angle θ is 30 degrees and during the first circulation cleaning operation. [Figure 18] FIG. 13 is a diagram showing the state near the filter 116 when the arrangement angle θ is 60 degrees and at a stage prior to the first circulation cleaning operation. [Figure 19] FIG. 13 is a diagram showing the state near the filter 116 when the arrangement angle θ is 75 degrees and at a stage prior to the first circulation cleaning operation. [Figure 20]FIG. 13 is a diagram showing the state near the filter 116 when the arrangement angle θ is 90 degrees and at a stage prior to the first circulation cleaning operation. [Figure 21] 11 is a diagram showing an example of a first flow rate of ink circulated in a first circulation cleaning operation and a second flow rate of ink circulated in a second circulation cleaning operation. FIG. [Figure 22] 13 is a flowchart showing the contents of a circulatory cleaning process of the head 10_1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the embodiments for carrying out the present invention will be described with reference to the drawings. However, in each drawing, the dimensions and scale of each part are appropriately different from the actual ones. In addition, since the embodiments described below are preferred specific examples of the present invention, various technically preferable limitations are attached, but the scope of the present invention is not limited to these embodiments unless otherwise specified in the following description to the effect that the present invention is limited.

[0009] In the following description, the mutually intersecting x-axis, y-axis, and z-axis are appropriately used. Moreover, one direction along the x-axis is called the x1 direction, and the direction opposite to the x1 direction is called the x2 direction. Similarly, the opposite directions along the y-axis are called the y1 direction and the y2 direction. Moreover, the opposite directions along the z-axis are called the z1 direction and the z2 direction. The xyz coordinate system having the x-axis, y-axis, and z-axis is a coordinate system fixed to the liquid ejection device. The orientation of the xyz coordinate system is determined so that the z2 direction is the direction of gravity and the z axis is parallel to the direction of gravity.

[0010] 1: First embodiment 1-1: Schematic configuration of liquid ejection device FIG. 1 is a schematic diagram showing an example of the configuration of a liquid ejection device 100 according to a first embodiment. The liquid ejection device 100 is an inkjet printing device that ejects ink, which is an example of a "liquid," as droplets onto a medium PP. The liquid ejection device 100 of this embodiment is a so-called line-type printing device in which a plurality of nozzles that eject ink are distributed across the entire range in the width direction of the medium PP. The medium PP is typically printing paper. Note that the medium PP is not limited to printing paper, and may be a printing target of any material, such as a resin film or fabric.

[0011] 1, the liquid ejection device 100 is equipped with a plurality of liquid supply sources 930 that store ink. The liquid supply sources 930 function as main tanks. Specific examples of the liquid supply sources 930 include a cartridge that is detachable from the liquid ejection device 100, a bag-shaped ink pack formed of a flexible film, and an ink tank that can be refilled with ink. The type of ink stored in the liquid supply sources 930 is arbitrary.

[0012] The liquid supply source 930 of this embodiment includes a first liquid container and a second liquid container, not shown. The storage section 93 stores ink to be supplied to the head 10 described later. The storage section 93 is an example of a "liquid storage section." A pump 931 is provided between each of the multiple liquid supply sources 930 and each of the multiple storage sections 93. The first liquid container stores a first ink. The second liquid container stores a second ink of a different type from the first ink. For example, the first ink and the second ink are inks of different colors. Note that the first ink and the second ink may be inks of the same type. The composition of the ink is not particularly limited, and may be, for example, any of a water-based ink in which a coloring material such as a dye or pigment is dissolved in a water-based solvent, an ultraviolet-curable ink, or a solvent-based ink.

[0013] The liquid ejecting device 100 includes a control unit 90, a storage unit 91, a conveying mechanism 92, a plurality of head modules 3, a plurality of circulation mechanisms 94, and a plurality of angle sensors 95 in addition to a plurality of liquid supply sources 930, a plurality of pumps 931, and a plurality of storage units 93. In the first embodiment, the liquid ejecting device 100 includes storage units 93, circulation mechanisms 94, and angle sensors 95 corresponding to the three head modules 3, respectively. Specifically, the liquid ejecting device 100 includes head modules 3_1 to 3_3, liquid supply sources 930_1 to 930_3, a plurality of pumps 931_1 to 931_3, storage units 93_1 to 93_3, circulation mechanisms 94_1 to 94_3, and angle sensors 95_1 to 95_3. However, the number of head modules 3 included in the liquid ejecting device 100 is not limited to three, and may be two, or may be four or more. Hereinafter, the liquid ejecting device 100 will be described as having three head modules 3. The head 10 in the head module 3_1 will be referred to as head 10_1. The head 10 in the head module 3_2 will be referred to as head 10_2. The head 10 in the head module 3_3 will be referred to as head 10_3. The head 10 is a collective term for the head 10_1, head 10_2, and head 10_3.

[0014] The storage unit 91 is configured with a magnetic storage device, a flash ROM, etc. ROM is an abbreviation for Read Only Memory. The storage unit 91 stores various programs and various data.

[0015] The control unit 90 controls the operation of each element of the liquid ejection device 100. The control unit 90 is, for example, a processing circuit such as a CPU or FPGA. CPU is an abbreviation for Central Processing Unit. FPGA is an abbreviation for Field Programmable Gate Array. The control unit 90 may be a multiprocessor having multiple processors. The control unit 90 reads out a program from the storage unit 91, executes the program, and realizes various controls by appropriately using data stored in the storage unit 91. The control unit 90 outputs a drive signal Com and a control signal SI to the head 10. The drive signal Com is a signal including a drive pulse that drives the drive elements Ea and Eb of the head 10. The control signal SI is a signal that specifies whether or not to supply the drive signal Com to the drive elements Ea and Eb.

[0016] The transport mechanism 92 transports the medium PP. The transport mechanism 92 has a drum 921 that transports the medium PP while adsorbing it to its outer circumferential surface, and a drive mechanism 922 such as a motor. The positional relationship between the drum 921 and the three head modules 3 is shown in FIG. 2.

[0017] 2 is a view of the liquid ejecting device 100 viewed in the x1 direction. The drum 921 is a cylindrical or columnar member having an outer circumferential surface along a central axis Ax parallel to the x-axis. The drum 921 is driven about the central axis Ax by a driving mechanism 922. The outer circumferential surface of the drum 921 is charged by a charger (not shown). The medium PP is electrostatically attracted to the outer circumferential surface of the drum 921 by electrostatic force due to this charge.

[0018] The head modules 3_1, 3_2, and 3_3 face the outer circumferential surface of the drum 921. The head modules 3_1, 3_2, and 3_3 have different postures around an axis parallel to the x-axis direction. Specifically, the head modules 3_1, 3_2, and 3_3 are arranged in this order along the outer circumferential surface of the drum 921 in the circumferential direction CD of the central axis Ax.

[0019] Further, each of the head modules 3_1, 3_2, and 3_3 is disposed at a position rotated around a rotation axis extending in the x1 direction, which is the longitudinal direction of the head module 3, so that the nozzle surface FN of the head 10 of the head module 3 is perpendicular to the radial direction RD of the central axis Ax of the drum 921 and inclined with respect to the horizontal plane SF. In the following, for the sake of simplicity of explanation, the angle formed by the nozzle surface FN and the horizontal plane SF may be referred to as an "arrangement angle θ". The nozzle surface FN_1 of the head 10_1 of the head module 3_1 is disposed so that the arrangement angle θ is an arrangement angle θ1. The nozzle surface FN_2 of the head 10_2 of the head module 3_2 is disposed so that the arrangement angle θ is an arrangement angle θ2. The nozzle surface FN_3 of the head 10_3 of the head module 3_3 is disposed so that the arrangement angle θ is an arrangement angle θ3. The angle between two planes is 0 degrees when the two planes are parallel, and when the two planes intersect, it is the acutest angle among the four angles formed by a first line segment and a second line segment perpendicular to the first intersection line between the two planes. The first line segment is a line segment that is perpendicular to the first intersection line and is included in one of the two planes. The second line segment is a line segment that is perpendicular to the first intersection line and is included in the other of the two planes.

[0020] 2, the arrangement angle θ1 is 0 degrees, the arrangement angle θ2 is 45 degrees, and the arrangement angle θ3 is 90 degrees. However, these arrangement angles θ1 to θ3 are merely examples, and for the sake of convenience in the following description, the angles may differ from those described here.

[0021] Returning to FIG. 1 for explanation, each of the three head modules 3 ejects ink, which is supplied from a storage unit 93 corresponding to each of the three head modules 3 via a circulation mechanism 94 corresponding to each of the three head modules 3, from each of the multiple nozzles onto the medium PP under the control of the control unit 90. Ink is supplied from a liquid supply source 930 corresponding to each of the three head modules 3 to the storage unit 93 corresponding to each of the three head modules 3 by a pump 931 controlled by the control unit 90. The three head modules 3 are a line head having multiple heads 10 arranged such that multiple nozzles are distributed over the entire range of the medium PP in the x-axis direction. In other words, the multiple heads 10 form a line head that is long in the direction in which the x-axis extends.

[0022] Each of the three circulation mechanisms 94 is a mechanism that supplies ink to each of the multiple heads 10 included in the head module 3 and collects ink discharged from each of the multiple heads 10 for resupply to the head 10. The circulation mechanism 94 has a supply path 941 for supplying ink from the storage unit 93 to the multiple heads 10, a recovery path 942 for recovering ink from the multiple heads 10 to the storage unit 93, and a flow mechanism 943 for appropriately flowing ink. The flow mechanism 943 is provided between the supply paths 941. The flow mechanism 943 flows the ink in the supply path 941 under the control of the control unit 90. The flow mechanism 943 is, for example, a pump or a compressor. By the operation of the circulation mechanism 94, it is possible to suppress an increase in the viscosity of the ink in the head 10 and to discharge air bubbles in the flow path of the head 10 to the outside of the head 10.

[0023] Each of the three angle sensors 95 measures the arrangement angle θ of the multiple heads 10 included in the head module 3, and transmits angle information DI indicating the measured arrangement angle to the control unit 90. More specifically, the angle sensor 95_1 measures the arrangement angle θ1 of any one of the multiple heads 10_1, and transmits angle information DI_1 indicating the arrangement angle θ1 to the control unit 90. The angle sensor 95_2 measures the arrangement angle θ2 of any one of the multiple heads 10_2, and transmits angle information DI_2 indicating the arrangement angle θ2 to the control unit 90. The angle sensor 95_3 measures the arrangement angle θ3 of any one of the multiple heads 10_3, and transmits angle information DI_3 indicating the arrangement angle θ3 to the control unit 90. Each of the three angle sensors 95 is disposed in the vicinity of any one of the multiple heads 10 included in the head module 3 in order to measure the arrangement angle θ of the head 10. In this embodiment, the liquid ejecting apparatus 100 has one angle sensor 95 corresponding to one head module 3, but the head 10 may have the angle sensor 95.

[0024] The liquid ejecting device 100 executes a printing process in which an image is formed on the surface of the medium PP by ejecting ink from the multiple head modules 3 in parallel with the transport mechanism 92 transporting the medium PP. Even during the printing process, the circulation mechanism 94 operates to circulate the ink between the storage unit 93 and the head 10. Furthermore, the liquid ejecting device 100 executes a maintenance process either before or after the printing process, or both. As one of the maintenance processes, the liquid ejecting device 100 executes a circulatory cleaning process in which the ink is circulated between the storage unit 93 and the head 10. The flow rate in the circulatory cleaning process is greater than the maximum flow rate in the printing process. The flow rate means the amount of liquid moved per unit period. The maximum flow rate in the printing process occurs when a so-called solid image is formed on the medium PP. In the following description, the flow rate in the circulatory cleaning process is referred to as the "circulatory cleaning flow rate." In addition, the period during which the circulatory cleaning is executed is referred to as the "circulatory cleaning period." For example, the maximum flow rate in the printing process is 0.9 [g / sec]. The circulating cleaning flow rate differs depending on the head 10, but is 1.0 [g / sec] or more.

[0025] The control unit 90 controls the three circulation mechanisms 94. More specifically, the control unit 90 controls the flow mechanism 943 in the circulation mechanism 94 to adjust the circulation cleaning flow rate and the circulation cleaning period. For example, when the flow mechanism 943 is a tube pump, the control unit 90 adjusts the circulation cleaning flow rate by changing the rotation speed of a rotor in the pump to achieve a desired flow rate. When the flow mechanism 943 is a compressor, the control unit 90 adjusts the differential pressure of the compressor to achieve a desired flow rate.

[0026] Hereinafter, the head module 3, which collectively refers to the head modules 3_1, 3_2, and 3_3, will be described with reference to FIG.

[0027] 1-2: Head module 3 configuration FIG. 3 is a perspective view of the head module 3. In the following description, an XYZ coordinate system is used in addition to the xyz coordinate system. One direction along the X axis is called the X1 direction, and the direction opposite to the X1 direction is called the X2 direction. Similarly, opposite directions along the Y axis are called the Y1 direction and the Y2 direction. Also, opposite directions along the Z axis are called the Z1 direction and the Z2 direction. The XYZ coordinate system is a local coordinate system that indicates coordinates based on the head module 3. When the attitude of the head module 3 changes, the orientation of the X axis direction, the orientation of the Y axis direction, and the orientation of the Z axis direction change. For example, as shown in FIG. 2, the Y axis direction in the head module 3_1 is different from the Y axis direction in the head module 3_2.

[0028] The head module 3 includes a plurality of heads 10 and a head fixing substrate 9 that holds the plurality of heads 10. The plurality of heads 10 are arranged in parallel along the X-axis and fixed to the head fixing substrate 9. The head module 3 may be a line head that is long in the direction in which the X-axis extends and is composed of only a single head 10 in which a plurality of nozzles N are distributed over the entire range of the medium PP in the X-axis direction. The head fixing substrate 9 has a plurality of mounting holes 9a for mounting the heads 10. The heads 10 are supported by the head fixing substrate 9 in a state in which they are inserted into the mounting holes 9a.

[0029] 1-3: Head 10 configuration FIG. 4 is an exploded perspective view of the head 10. As shown in FIG. 4, the head 10 has a flow path structure 11, a wiring board 12, a holder 13, a plurality of head chips 14_1, 14_2, 14_3, 14_4, 14_5, and 14_6, a fixing plate 15, and a base 16. These are arranged in the Z2 direction in the order of the base 16, the flow path structure 11, the wiring board 12, the holder 13, a plurality of head chips 14_1, 14_2, 14_3, 14_4, 14_5, and 14_6, and the fixing plate 15. Each part of the head 10 will be described below in order. Note that, hereinafter, each of the head chips 14_1, 14_2, 14_3, 14_4, 14_5, and 14_6 may be referred to as a head chip 14.

[0030] The flow path structure 11 is a structure in which a flow path for flowing ink between the circulation mechanism 94 and the plurality of head chips 14 is provided. As shown in FIG. 4, the flow path structure 11 has a flow path member 110 and connection pipes 11a, 11b, 11c, and 11d. Although not shown in FIG. 4, the flow path member 110 is provided with an inflow flow path for the first ink to flow into the plurality of head chips 14, an inflow flow path for the second ink to flow into the plurality of head chips 14, an outflow flow path for the first ink to flow out from the plurality of head chips 14, and an outflow flow path for the second ink to flow out from the plurality of head chips 14. Specifically, the connection pipes 11a and 11b communicate with the inflow flow path, and the connection pipes 11c and 11d communicate with the outflow flow path. Between the connection pipe 11a and the inflow flow path, and between the connection pipe 11b and the inflow flow path, a filter 116 for capturing foreign matter and the like is provided. However, the filter 116 may be provided in the middle of the inflow flow path.

[0031] FIG. 5 is a cross-sectional view taken along line AA in FIG. 4. Line AA is a virtual straight line parallel to the Y-axis and cutting connecting tube 11b. Connecting tube 11b is a hollow needle-shaped member, and is provided with ink introduction hole 112, ink introduction path 113, and upstream chamber 117A. Ink introduction hole 112 is provided at the end of connecting tube 11b in the Z1 direction, and communicates with ink introduction path 113. Ink introduction path 113 is an internal space of connecting tube 11b, and communicates ink introduction hole 112 with upstream chamber 117A. In FIG. 5, flow path member 110 is shown with flow path 118, which is a part of the inflow flow path.

[0032] The air bubble chamber 114 defines a part of the filter chamber 117 that includes the filter 116. The filter chamber 117 is divided by the filter 116 into an upstream chamber 117A located relatively in the Z1 direction and a downstream chamber 117B located relatively in the Z2 direction. The upstream chamber 117A has an air bubble chamber 114 that temporarily stores air bubbles contained in the ink, and an expanded portion 117a1 that is disposed between the air bubble chamber 114 and the filter 116. When the filter chamber 117 is viewed in the Z-axis direction, which is the thickness direction of the filter 116, the area of ​​the expanded portion 117a1 is larger than the area of ​​the air bubble chamber 114. The maximum dimension d1 in the Z-axis direction, which is the thickness direction of the expanded portion 117a1, is smaller than the difference d2 between the outer periphery OC1 of the air bubble chamber 114 and the outer periphery OC2 of the expanded portion 117a1 in the XY plane when viewed in the Z-axis direction. The air bubbles stored in the air bubble chamber 114 flow through the widened portion 117a1, the filter 116, and the downstream chamber 117B in this order, and then flow out of the filter chamber 117 from the flow path 118.

[0033] The filter 116 is a plate- or sheet-shaped member that allows the ink to pass through while capturing foreign matter mixed into the ink. The filter 116 is provided along the XY plane. The filter 116 is made of, for example, metal fibers such as twill weave or plain weave. The filter 116 is not limited to a configuration using metal fibers, and may be made of, for example, resin fibers such as nonwoven fabric.

[0034] 5 shows filter 116 arranged between connecting pipe 11b and the inflow flow path, but filter 116 arranged between connecting pipe 11a and the inflow flow path has substantially the same configuration as filter 116 arranged between connecting pipe 11b and the inflow flow path. "Substantially the same" includes cases where they are completely the same, as well as cases where they can be considered to be the same taking manufacturing errors into consideration.

[0035] Returning to Fig. 4 for explanation, the flow path member 110 is composed of a plurality of plate-like members. By appropriately providing grooves or holes in these plurality of plate-like members, flow paths such as inflow flow paths and outflow flow paths are formed. The flow path member 110 is provided with a hole 110a into which a connector 12c, which will be described later, is inserted. Connection pipes 11a, 11b, 11c, and 11d protrude from the surface of the flow path member 110 facing the Z1 direction.

[0036] The connecting tube 11a is a tube that constitutes a flow path for supplying a first ink to the flow path member 110. The connecting tube 11b is a tube that constitutes a flow path for supplying a second ink to the flow path member 110. On the other hand, the connecting tube 11c is a tube that constitutes a flow path for discharging the first ink from the flow path member 110. The connecting tube 11d is a tube that constitutes a flow path for discharging the second ink from the flow path member 110.

[0037] The wiring board 12 is a mounting component for electrically connecting the head chips 14 and the assembly board 16b described later. The wiring board 12 is, for example, a rigid wiring board. The wiring board 12 is disposed between the flow path structure 11 and the holder 13, and a connector 12c is disposed on the surface of the wiring board 12 facing the flow path structure 11. The connector 12c is a connection part connected to the assembly board 16b described later. The wiring board 12 is also provided with a plurality of holes 12a and a plurality of openings 12b. Each hole 12a is a hole for allowing the connection between the flow path structure 11 and the holder 13. Each opening 12b is a hole through which a wiring member 14a that connects the head chip 14 and the wiring board 12 is passed. The wiring member 14a is connected to the surface of the wiring board 12 facing the Z1 direction. The wiring member 14a is a member including wiring electrically connected to the driving element Ea or Eb described later, and is, for example, an FPC or a COF. FPC is an abbreviation for Flexible Printed Circuits, and COF is an abbreviation for Chip On Film.

[0038] The holder 13 is a structure that houses and supports a plurality of head chips 14. The holder 13 is made of, for example, a resin material or a metal material. The holder 13 is in the form of a plate extending in a direction perpendicular to the Z axis. The holder 13 is provided with a plurality of ink holes 13a and a plurality of wiring holes 13b. Each ink hole 13a is an opening on the flow path on the flow path structure 11 side in a flow path that allows ink to flow between the head chip 14 and the flow path structure 11. Each wiring hole 13b is a hole through which a wiring member 14a that connects the head chip 14 and the wiring board 12 is passed. Here, the inside of the holder 13 has, although not shown, an inflow flow path through which the first ink flows into the head chip 14, an inflow flow path through which the second ink flows into the head chip 14, a circulation flow path for flowing the first ink from the head chip 14 to the outflow flow path of the flow path structure 11, and a circulation flow path for flowing the second ink from the head chip 14 to the outflow flow path of the flow path structure 11. Although not shown, branch flow paths are provided inside holder 13 for distributing or collecting ink between each ink hole 13a and the multiple head chips 14. Although not shown, a surface of holder 13 facing the Z2 direction is provided with a plurality of recesses for accommodating the multiple head chips 14.

[0039] The head chip 14 ejects ink. Specifically, although not shown in FIG. 4, each head chip 14 has a plurality of nozzles N that eject a first ink and a plurality of nozzles N that eject a second ink. These nozzles N are provided on a nozzle surface FN, which is a surface of each head chip 14 facing the Z2 direction. The configuration of the head chip 14 will be described later. The nozzle surface FN is provided along the XY plane. As described above, the filter 116 is also provided along the XY plane. Therefore, the filter 116 is provided approximately parallel to the nozzle surface FN. "Approximately parallel" includes cases where the nozzles are completely parallel, as well as cases where the nozzles can be considered to be parallel when manufacturing errors are taken into consideration.

[0040] Fixing plate 15 is a plate member for fixing multiple head chips 14 to holder 13. Specifically, fixing plate 15 is arranged with multiple head chips 14 sandwiched between fixing plate 15 and holder 13, and is fixed to holder 13 by adhesive. Fixing plate 15 is made of, for example, a metal material. Fixing plate 15 is provided with multiple openings 15a for exposing nozzles of the multiple head chips 14. In the example shown in FIG. 4, the multiple openings 15a are provided individually for each head chip 14. Note that openings 15a may be shared by two or more head chips 14.

[0041] The base 16 is a member for fixing the flow path structure 11, the wiring board 12, the holder 13, the head chips 14, and the fixing plate 15 to the head fixing substrate 9. The base 16 has a main body 16a, an assembly substrate 16b, and a cover 16c.

[0042] The main body 16a is fixed to the holder 13 by screwing or the like, thereby holding the flow path structure 11 and the wiring board 12 disposed between the base 16 and the holder 13. The main body 16a is made of, for example, a resin material or the like. The main body 16a has a plate-like portion facing the above-mentioned flow path member 110, and the plate-like portion is provided with a plurality of holes 16d into which the above-mentioned connection pipes 11a, 11b, 11c, and 11d are inserted. The main body 16a also has a portion extending from the plate-like portion in the Z2 direction, and a flange 16e for fixing to the head fixing substrate 9 is provided at the tip of the portion.

[0043] The collective substrate 16b is a mounting component for electrically connecting the control unit 90 and the wiring substrate 12 described above. The collective substrate 16b is, for example, a rigid wiring substrate. The cover 16c is a plate-like member for protecting the collective substrate 16b and for fixing the collective substrate 16b to the main body 16a. The cover 16c is made of, for example, a resin material, and is fixed to the main body 16a by screws or the like.

[0044] 1-4: Head chip 14 Fig. 6 is a plan view of the head chip 14. Fig. 6 shows a schematic diagram of the internal structure of the head chip 14 as viewed in the Z1 direction. As shown in Fig. 6, the head chip 14 has a liquid ejecting section Qa and a liquid ejecting section Qb. The liquid ejecting section Qa has a nozzle row La consisting of a plurality of nozzles N that ejects a first ink supplied from the circulation mechanism 94 described above. The liquid ejecting section Qb has a nozzle row Lb consisting of a plurality of nozzles N that ejects a second ink supplied from the circulation mechanism 94. The plurality of nozzles N in each of the nozzle row La and the nozzle row Lb are arranged in the direction DN.

[0045] The liquid ejection unit Qa has a common liquid chamber Ra, multiple pressure chambers Ca, and multiple drive elements Ea. The common liquid chamber Ra is continuous across the multiple nozzles N of the nozzle row La. Each of the pressure chambers Ca and the drive elements Ea is provided for each nozzle N of the nozzle row La. The pressure chamber Ca is a space that communicates with the nozzle N. Each of the multiple pressure chambers Ca is filled with the first ink supplied from the common liquid chamber Ra. The drive elements Ea vary the pressure of the first ink in the pressure chamber Ca. The drive elements Ea are, for example, piezoelectric elements that change the volume of the pressure chamber Ca by deforming the wall surface of the pressure chamber Ca, or heating elements that generate air bubbles in the pressure chamber Ca by heating the first ink in the pressure chamber Ca. The drive elements Ea are driven by a drive signal Com to vary the pressure of the first ink in the pressure chamber Ca, causing the first ink in the pressure chamber Ca to be ejected from the nozzle N.

[0046] Like the liquid ejection unit Qa, the liquid ejection unit Qb has a common liquid chamber Rb, multiple pressure chambers Cb, and multiple drive elements Eb. The common liquid chamber Rb is continuous across the multiple nozzles N of the nozzle row Lb. Each of the pressure chambers Cb and the drive elements Eb is provided for each nozzle N of the nozzle row Lb. Each of the multiple pressure chambers Cb is filled with the second ink supplied from the common liquid chamber Rb. The drive elements Eb are, for example, the above-mentioned piezoelectric elements or heat generating elements. The drive elements Eb are driven by a drive signal Com to vary the pressure of the second ink in the pressure chambers Cb, causing the second ink in the pressure chambers Cb to be ejected from the nozzles N.

[0047] As shown in Fig. 6, the head chip 14 is provided with an inlet Ra_in, an outlet Ra_out, an inlet Rb_in, and an outlet Rb_out. The inlet Ra_in and the outlet Ra_out each communicate with the common liquid chamber Ra. The inlet Rb_in and the outlet Rb_out each communicate with the common liquid chamber Rb. Hereinafter, the inlet Ra_in and the inlet Rb_in will be collectively referred to as the inlet R_in. The outlet Ra_out and the outlet Rb_out will be collectively referred to as the outlet R_out.

[0048] In the head chip 14 described above, the first ink that is not ejected from each nozzle N of the nozzle row La and is stored in the common liquid chamber Ra circulates via the outlet port Ra_out, the circulation flow path for the first ink in the holder 13, the outflow flow path for the first ink in the flow path structure 11, the storage section 93 for the first ink in the circulation mechanism 94, the inflow flow path for the first ink in the flow path structure 11, the inflow flow path for the first ink in the holder 13, the introduction port Ra_in, and the common liquid chamber Ra in this order. Similarly, the second ink that is not ejected from each nozzle N of the nozzle row Lb and is stored in the common liquid chamber Rb circulates via the outlet port Rb_out, the circulation flow path for the second ink in the holder 13, the outflow flow path for the second ink in the flow path structure 11, the storage section 93 for the second ink in the circulation mechanism 94, the inflow flow path for the second ink in the flow path structure 11, the inflow flow path for the second ink in the holder 13, the introduction port Rb_in, and the common liquid chamber Rb in this order.

[0049] 1-5: Air bubbles in the upstream chamber 117A If air bubbles are generated in the upstream chamber 117A, there is a risk that the air bubbles will clog a portion of the filter 116. This will increase the pressure loss in the filter 116, causing the ink supply pressure to fluctuate, which may result in a meniscus not being formed properly in the nozzle N and causing an ejection abnormality. An ejection abnormality is a state in which, even if an attempt is made to eject ink from the nozzle N by the drive signal Com, the ink cannot be ejected in the manner defined by the drive signal Com. Here, the ink ejection manner defined by the drive signal Com means that the nozzle N ejects an amount of ink defined by the waveform of the drive signal Com, and that the nozzle N ejects ink at an ejection speed defined by the waveform of the drive signal Com. In other words, a state in which ink cannot be ejected according to the ink ejection pattern specified by the drive signal Com includes, in addition to a state in which ink cannot be ejected from nozzle N, a state in which a smaller amount of ink is ejected from nozzle N than the ink ejection amount specified by the drive signal Com, a state in which a larger amount of ink is ejected from nozzle N than the ink ejection amount specified by the drive signal Com, or a state in which ink cannot land at the desired landing position on medium PP because ink is ejected at a speed different from the ink ejection speed specified by the drive signal Com.

[0050] 1-5-1: Issues with conventional circulation cleaning operations Even with the conventional circulation cleaning operation, some of the air bubbles in the upstream chamber 117A can be discharged from the filter chamber 117. However, with the conventional circulation cleaning operation, minute air bubbles smaller than the aforementioned some of the air bubbles may remain in the filter chamber 117.

[0051] Fig. 7 is a diagram showing a state immediately before the execution of a circulation cleaning operation, that is, a state in which air bubbles have invaded and grown in the upstream chamber 117A due to the passage of a predetermined period from the previous circulation cleaning operation through a printing period in which printing is performed until the execution of the current circulation cleaning operation. Fig. 7 is also a diagram showing a state near the filter 116 when the arrangement angle θ is 45 degrees and during printing. Fig. 8 is a diagram showing a state near the filter 116 when the arrangement angle θ is 45 degrees and during the circulation cleaning operation. Fig. 9 is a diagram showing a state near the filter 116 when the arrangement angle θ is 45 degrees and after the circulation cleaning operation.

[0052] As shown in FIG. 7 and FIG. 8, in the upstream chamber 117A, a large bubble Bu exists at the end of the bubble chamber 114 in the z1 direction due to buoyancy. In the upstream chamber 117A, a small bubble bb exists near the end of the widened portion 117a1 in the Y1 direction due to buoyancy. In the state shown in FIG. 7, the large bubble Bu and the small bubble bb exist at different positions in the upstream chamber 117A. If the large bubble Bu comes into contact with the filter 116 during printing and clogs a part of the filter 116, ejection abnormalities are likely to occur as described above. Therefore, during printing, that is, before the circulation cleaning operation, it is preferable that the large bubble Bu is separated from the filter 116. As shown in FIG. 7, the large bubble Bu is located away from the filter 116 in the z1 direction. FIG. 7 shows the center of gravity G45P of the large bubble Bu when the arrangement angle θ is 45 degrees and when printing. The center of gravity is the point where the sum of the first moments of area becomes zero in the target shape.

[0053] During the circulatory cleaning operation, the large bubbles Bu need to come into contact with the filter 116 in order to be discharged in the Z2 direction. In the example shown in Fig. 8, the circulatory cleaning operation causes ink to flow in the Z2 direction at a flow rate greater than during printing, so the large bubbles Bu move in the Z2 direction. Fig. 8 shows a case in which the arrangement angle θ is 45 degrees and the center of gravity G45C of the large bubbles Bu during the circulatory cleaning operation.

[0054] As shown in Fig. 8, because the ink flows in the Z2 direction, the large bubble Bu moves in the Z2 direction, but a buoyant force BF toward the z1 direction is generated on the large bubble Bu. In the example shown in Fig. 8, the ink flow direction and the direction of the buoyant force BF intersect. Therefore, the Z1 direction component of the buoyant force BF is offset by the ink flow, but the Y1 direction component of the buoyant force BF is not offset by the ink flow. As shown in Fig. 8, the movement distance of the large bubble Bu when the arrangement angle θ is 45 degrees is the distance L45 from the center of gravity G45P shown in Fig. 7 to the center of gravity G45C shown in Fig. 8.

[0055] As a result of the large bubble Bu moving in the Z2 direction, the large bubble Bu comes into contact with the filter 116. The area of ​​contact of the large bubble Bu with the filter 116 is R45 in the example shown in Fig. 8. While the component of the buoyancy force BF in the Y1 direction is not offset by the flow of ink, the large bubble Bu moves in the Z2 direction in conjunction with the flow of ink in the Z2 direction, resulting in the large bubble Bu becoming elongated in the Z axis direction such that it is in contact with the wall surface of the air bubble chamber 114 in the Z1 direction and in contact with the filter 116 in the Z2 direction. The width of the large bubble Bu in the Y axis direction becomes shorter by the amount that the shape becomes elongated in the Z axis direction.

[0056] Since the width of the large bubble Bu in the Y-axis direction becomes shorter and the small bubble bb exists in the Y1 direction as seen from the large bubble Bu, the large bubble Bu does not come into contact with the small bubble bb in the widened portion 117a1. Therefore, the small bubble bb is not absorbed by the large bubble Bu in the widened portion 117a1, and as a result, does not disappear.

[0057] Thereafter, as ink continues to flow in, the large bubbles Bu pass through the filter 116 and then flow out of the filter chamber 117 from the flow path 118. However, as shown in Fig. 9, small bubbles bb remain near the end of the widened portion 117a1 in the Y1 direction. Thus, if a printing process is performed again with small bubbles bb remaining in the widened portion 117a1, the small bubbles bb will clog the filter 116, increasing the pressure loss of the filter 116 and creating a risk of ejection abnormalities.

[0058] 1-5-2: Circulation cleaning operation in this embodiment Therefore, in this embodiment, the control unit 90 executes two circulation cleaning operations, a first circulation cleaning operation and a second circulation cleaning operation. The first circulation cleaning operation is an operation of circulating the ink at a first flow rate. The second circulation cleaning operation is an operation of circulating the ink at a second flow rate that is greater than the first flow rate. Here, the "first flow rate" is a flow rate at which air bubbles of a predetermined size or more do not pass through the filter 116. More specifically, the "first flow rate" is a flow rate at which large bubbles Bu, which are the largest air bubbles present in the upstream chamber 117A, do not pass through the filter 116. The "second flow rate" is a flow rate at which air bubbles of the predetermined size or more pass through the filter 116. More specifically, the "second flow rate" is a flow rate at which large bubbles Bu, which are the largest air bubbles present in the upstream chamber 117A, pass through the filter 116. Here, the "flow rate" refers to the amount of ink passing through the filter 116 per unit time. Moreover, air bubbles of a "predetermined size" refer to air bubbles that are too large to pass through the filter 116 even when the maximum flow rate of ink during a printing operation passes through the filter 116. As an example, air bubbles of a "predetermined size" are air bubbles that are larger than the size of the holes in the filter 116.

[0059] The first flow rate is greater than the maximum flow rate of ink passing through the filter 116 during printing.

[0060] Furthermore, in this embodiment, the control unit 90 causes the large bubbles Bu to come into contact with the small bubbles bb in the first circulation cleaning operation, so that the small bubbles bb are absorbed by the large bubbles Bu. As a result, the large bubbles Bu and the small bubbles bb are integrated into a new large bubble Bu. Thereafter, the control unit 90 causes the new large bubbles Bu to pass through the filter 116 and then flow out of the filter chamber 117 from the flow path 118 in the second circulation cleaning operation. As a result, the small bubbles bb do not remain in the widened portion 117a1. In addition, when a printing operation is performed again, the risk of the filter 116 being clogged by the small bubbles bb is reduced. The second circulation cleaning operation corresponds to the conventional circulation cleaning operation shown in FIG. 8.

[0061] In this embodiment, the control unit 90 executes a circulatory cleaning process for executing a second circulatory cleaning operation after executing a first circulatory cleaning operation on the head module 3. Here, the first circulatory cleaning operation is an example of a "first circulatory operation". The second circulatory cleaning operation is an example of a "second circulatory operation". The circulatory cleaning process for executing a second circulatory cleaning operation after executing a first circulatory cleaning operation is an example of a "first circulatory cleaning process".

[0062] Fig. 10 is a diagram showing the state around filter 116 when the arrangement angle θ is 45 degrees and during the first circulation cleaning operation. Fig. 11 is a diagram showing the state around filter 116 when the arrangement angle θ is 45 degrees and during the second circulation cleaning operation. Fig. 12 is a diagram showing the state around filter 116 when the arrangement angle θ is 45 degrees and after the second circulation cleaning operation.

[0063] Before the first circulation cleaning operation, the state is similar to the state around the filter 116 during printing, as shown in Fig. 7. Specifically, small air bubbles bb are present near the end of the widened portion 117a1 in the Y1 direction.

[0064] Thereafter, the control unit 90 executes a first circulation cleaning operation shown in FIG. 10. The first flow rate in the first circulation cleaning operation is less than the second flow rate in the second circulation cleaning operation corresponding to the conventional circulation cleaning operation. Therefore, the force moving the large bubble Bu in the Z2 direction is weakened compared to the state in FIG. 8 showing the conventional circulation cleaning operation, and the large bubble Bu extends to the end in the Y1 direction in the widened portion 117a1 due to the buoyancy BF. Furthermore, the large bubble Bu cannot pass through the filter 116 and is pressed against the filter 116, so that it extends in the extension direction of the filter 116. As a result, the small bubble bb is absorbed by the large bubble Bu, and the two are integrated into a new large bubble Bu.

[0065] After performing the first circulation cleaning operation, the control unit 90 performs a second circulation cleaning operation shown in Fig. 11. The state shown in Fig. 11 differs from the state shown in Fig. 8 in that small bubbles bb are not formed near the end of the widened portion 117a1 in the Y1 direction.

[0066] The control unit 90 causes new large bubbles Bu shown in Fig. 11 to pass through the filter 116 and then flow out of the filter chamber 117 from the flow path 118 by the second circulation cleaning operation. As a result, as shown in Fig. 12, small bubbles bb do not remain near the end of the widened portion 117a1 in the Y1 direction. This in turn reduces the risk of the filter 116 becoming clogged with small bubbles bb when the printing process is executed again.

[0067] After the second circulation cleaning operation, the control unit 90 executes a standby operation to stop the circulation of ink by the circulation mechanism 94 for a predetermined time. The predetermined time is at least 30 seconds or more, and preferably 1 to 5 minutes. This predetermined time corresponds to the period during which the driving of the flow mechanism 943 is stopped. By executing the standby operation by the control unit 90, even if the small bubbles bb are not completely removed and as a result the small bubbles bb are attached to the surface of the filter 116, the small bubbles bb can move vertically upward of the widened portion 117a1 due to buoyancy. As a result, it is possible to prevent the filter 116 from becoming clogged by the small bubbles bb present in the gaps at the outer circumferential end of the widened portion 117a1, which would increase the pressure loss.

[0068] After the control unit 90 performs the standby operation, the control unit 90 executes the printing operation, or the control unit 90 enters a state in which the control unit 90 waits for the printing operation itself.

[0069] The first circulation cleaning operation and the second circulation cleaning operation when the arrangement angle θ is 45 degrees have been described above with reference to Figures 10 to 12. Below, the first circulation cleaning operation and the second circulation cleaning operation at other arrangement angles θ will be described with reference to Figures 13 to 20.

[0070] Fig. 13 is a diagram showing the state around filter 116 when the arrangement angle θ is 0 degrees and at a stage before the first circulation cleaning operation. Fig. 14 is a diagram showing the state around filter 116 when the arrangement angle θ is 0 degrees and during the first circulation cleaning operation. Fig. 15 is a diagram showing the state around filter 116 when the arrangement angle θ is 0 degrees and during the second circulation cleaning operation.

[0071] 13, the large bubbles Bu are located away from the filter 116 in the z1 direction. Small bubbles bb exist near the ends of the widened portion 117a1 in the Y1 direction and in the Y2 direction.

[0072] After that, the control unit 90 executes the first circulation cleaning operation shown in FIG. 14. During the first circulation cleaning shown in FIG. 14, the large bubble Bu needs to extend to the end of the widened portion 117a1 in order to absorb the small bubble bb. In the example shown in FIG. 14, the first circulation cleaning causes the ink to flow in the Z2 direction at a first flow rate that is greater than that during printing, so the large bubble Bu moves in the Z2 direction. However, the large bubble Bu generates a buoyancy force BF toward the z1 direction. In the example shown in FIG. 14, the Z2 direction and the z1 direction are parallel and opposite to each other, so that the buoyancy force BF can be offset by the flow of the ink. Furthermore, during the circulation of the ink at the first flow rate, the large bubble Bu does not pass through the filter 116. For this reason, as shown in FIG. 14, the large bubble Bu extends to the end of the widened portion 117a1.

[0073] After performing the first circulation cleaning operation, the control unit 90 performs a second circulation cleaning operation shown in FIG. 15. During the second circulation cleaning shown in FIG. 15, the large bubbles Bu need to come into contact with the filter 116 in order to discharge the large bubbles Bu in the Z2 direction. In the example shown in FIG. 15, the ink flows in the Z2 direction at a second flow rate that is greater than that during the first circulation cleaning, and the large bubbles Bu move in the Z2 direction. However, a buoyancy force BF toward the z1 direction is generated in the large bubbles Bu. In the example shown in FIG. 15, the Z2 direction and the z1 direction are parallel and opposite to each other, so that the buoyancy force BF can be offset by the flow of the ink. As a result of the large bubbles Bu moving in the Z2 direction, the large bubbles Bu come into contact with the filter 116.

[0074] 15 passes through the filter 116, and then flows out of the filter chamber 117 through the flow path 118. As a result, small bubbles bb do not remain near the Y1-direction end and the Y2-direction end of the widened portion 117a1. This reduces the risk of the filter 116 becoming clogged with small bubbles bb when the printing process is executed again.

[0075] After performing the second circulation cleaning operation, the control unit 90 executes the above-mentioned standby operation.

[0076] Fig. 16 is a diagram showing the state around filter 116 when the arrangement angle θ is 30 degrees and at a stage before the first circulation cleaning operation, and Fig. 17 is a diagram showing the state around filter 116 when the arrangement angle θ is 30 degrees and during the first circulation cleaning operation.

[0077] The state before the first circulation cleaning operation is similar to the state near the filter 116 during printing, as shown in Fig. 7. Specifically, small air bubbles bb are formed near the end of the widened portion 117a1 in the Y1 direction.

[0078] Thereafter, the control unit 90 executes the first circulation cleaning operation shown in FIG. 17. As in the first circulation cleaning operation shown in FIG. 10 when the arrangement angle θ is 45 degrees, the large bubble Bu extends to the end in the Y1 direction in the widened portion 117a1 due to the buoyancy BF. Furthermore, since the large bubble Bu cannot pass through the filter 116 and is pressed against the filter 116, the large bubble Bu extends to the end in the Y1 direction. As a result, the small bubble bb is absorbed into the large bubble Bu, and both are integrated as a new large bubble Bu. Note that, compared to the first circulation cleaning operation shown in FIG. 14 when the arrangement angle θ is 0 degrees, the large bubble Bu shown in FIG. 17 is less likely to be subjected to the buoyancy BF in the Z1 direction, and is therefore easier to move in the Z2 direction toward the filter 116. Furthermore, the large bubble Bu moved to the filter 116 is more likely to extend toward the end in the Y1 direction due to the buoyancy compared to the case when the arrangement angle θ is 0 degrees. For this reason, the first flow rate when the arrangement angle θ is 30 degrees is less than the first flow rate when the arrangement angle θ is 0 degree. On the other hand, compared to the first circulation cleaning operation when the arrangement angle θ is 45 degrees shown in Fig. 10, the large bubble Bu shown in Fig. 17 is more likely to be subjected to a buoyancy force BF in the Z1 direction. For this reason, the first flow rate when the arrangement angle θ is 30 degrees is greater than the first flow rate when the arrangement angle θ is 45 degrees.

[0079] The control unit 90 executes the second circulation cleaning operation after executing the first circulation cleaning operation. The second circulation cleaning operation when the arrangement angle θ is 30 degrees is the same as the second circulation cleaning operation when the arrangement angle θ is 45 degrees shown in FIG. 11, and is therefore omitted from the illustration. Note that when the arrangement angle θ is 30 degrees, the buoyancy BF acts on the end of the large bubble Bu in the Y2 direction to move away from the filter 116 during the second circulation cleaning operation, compared to when the arrangement angle θ is 0 degrees, so that the area of ​​contact of the large bubble Bu with the filter 116 is reduced, making it difficult for the large bubble Bu to pass through the filter 116. For this reason, it is preferable to set the second flow rate when the arrangement angle θ is 30 degrees higher than the second flow rate when the arrangement angle θ is 0 degrees.

[0080] The control unit 90 causes the new large bubbles Bu to pass through the filter 116 and then flow out of the filter chamber 117 through the flow path 118 by the second circulation cleaning operation. As a result, small bubbles bb do not remain near the end of the widened portion 117a1 in the Y1 direction. This in turn reduces the risk of the filter 116 becoming clogged with small bubbles bb when the printing process is executed again.

[0081] After performing the second circulation cleaning operation, the control unit 90 executes the above-mentioned standby operation.

[0082] Fig. 18 is a diagram showing the state around filter 116 when the arrangement angle θ is 60 degrees and at a stage prior to the first circulation cleaning operation. Fig. 19 is a diagram showing the state around filter 116 when the arrangement angle θ is 75 degrees and at a stage prior to the first circulation cleaning operation. Fig. 20 is a diagram showing the state around filter 116 when the arrangement angle θ is 90 degrees and at a stage prior to the first circulation cleaning operation.

[0083] At these arrangement angles θ, the large bubbles Bu extend to the end of the widened portion 117a1 in the Y1 direction due to buoyancy BF before the first circulation cleaning operation. In other words, even if the control unit 90 does not perform the first circulation cleaning operation, the small bubbles bb are integrated into the large bubbles Bu in advance. For this reason, at these arrangement angles θ, the control unit 90 omits the first circulation cleaning operation and performs only the second circulation cleaning operation. The second circulation cleaning operation at these arrangement angles θ is similar to the second circulation cleaning operation when the arrangement angle θ is 45 degrees shown in FIG. 11, for example, except for the difference in the arrangement angle θ, and is therefore not shown in the figures.

[0084] The control unit 90 causes the large bubbles Bu to pass through the filter 116 and then flow out of the filter chamber 117 from the flow path 118 by the second circulation cleaning operation. As a result, small bubbles bb do not remain near the end of the widened portion 117a1 in the Y1 direction. This in turn reduces the risk of the filter 116 becoming clogged with small bubbles bb when the printing process is executed again.

[0085] After performing the second circulation cleaning operation, the control unit 90 executes the above-mentioned standby operation.

[0086] 1-6: An example of the first flow rate and the second flow rate Fig. 21 is a diagram showing an example of a first flow rate of ink circulated in a first circulation cleaning operation and a second flow rate of ink circulated in a second circulation cleaning operation. Table T1 shown in Fig. 21 has records 160_1 to 160_7. The storage unit 91 stores table T1.

[0087] Table T1 shows an example of specific values ​​of the first flow rate and the second flow rate for each of the arrangement angles θ of 0 degrees, 15 degrees, 30 degrees, 45 degrees, 60 degrees, 75 degrees, and 90 degrees. The units of the first flow rate and the second flow rate shown in Fig. 16 are [g / sec], that is, they show so-called mass flow rates.

[0088] Record 160_1 indicates that when the arrangement angle θ is 0 degrees, the first flow rate is 1.2 [g / sec] and the second flow rate is 1.5 [g / sec]. Record 160_2 indicates that when the arrangement angle θ is 15 degrees, the first flow rate is 1.15 [g / sec] and the second flow rate is 1.55 [g / sec]. Record 160_3 indicates that when the arrangement angle θ is 30 degrees, the first flow rate is 1.1 [g / sec] and the second flow rate is 1.6 [g / sec]. Record 160_4 indicates that when the arrangement angle θ is 45 degrees, the first flow rate is 1.0 [g / sec] and the second flow rate is 1.7 [g / sec]. Record 160_5 indicates that when the arrangement angle θ is 60 degrees, the first flow rate is 0 [g / sec] and the second flow rate is 2.0 [g / sec]. Record 160_6 indicates that the first flow rate is 0 [g / sec] and the second flow rate is 1.5 [g / sec] when the arrangement angle θ is 75 degrees. Record 160_7 indicates that the first flow rate is 0 [g / sec] and the second flow rate is 1.5 [g / sec] when the arrangement angle θ is 90 degrees.

[0089] In table T1, the first flow rate decreases as the arrangement angle θ increases within the range of 0 degrees to 45 degrees. This is because, as the arrangement angle θ increases, the degree to which the buoyancy force BF offsets the movement of the ink in the Z2 direction decreases and the Y1 direction component of the buoyancy force BF increases, making it easier for the large bubble Bu to extend to the end of the widened portion 117a1 in the Y1 direction. When the arrangement angle θ is 0 degrees, the first flow rate is 1.2 [g / sec].

[0090] When the arrangement angle θ is 0 degrees, there is a risk that the small bubbles bb will remain at the outer peripheral end of the widened portion 117a1. In such a case, the control unit 90 executes the first circulation cleaning operation with the first flow rate set to 1.2 [g / sec]. When the first circulation cleaning operation is executed with the arrangement angle θ being 0 degrees, it is necessary to press the large bubbles Bu against the filter 116 and extend them in the horizontal direction so that the large bubbles Bu will spread to the outer peripheral end of the widened portion 117a1. Therefore, it is preferable that the first flow rate is higher than when the arrangement angle θ is greater than 0 degrees (for example, when the arrangement angle θ is 15 degrees or 30 degrees).

[0091] When the arrangement angle θ is 0 degrees, the first flow rate may be 0 [g / sec]. This is because when the arrangement angle θ is 0 degrees, the small bubbles bb at the outer peripheral end of the widened portion 117a1 may naturally rise to the bubble chamber 114 due to the influence of buoyancy depending on the shape of the widened portion 117a1.

[0092] Furthermore, as described above, when the arrangement angle θ is 60 degrees, 75 degrees, and 90 degrees, the control unit 90 does not need to execute the first circulation cleaning operation.

[0093] In table T1, the degree to which large bubbles Bu are discharged changes with an increase in the arrangement angle θ with respect to the second flow rate. Therefore, as shown in Fig. 21, the second flow rate increases monotonically with an increase in the arrangement angle θ when the arrangement angle θ is between 0 degrees and 60 degrees, and at arrangement angles θ of 75 degrees and 90 degrees, the second flow rate is the same as when the arrangement angle θ is 0 degrees. This is because, when the arrangement angle θ is 75 degrees or more, it becomes more difficult for the buoyancy force BF acting on the large bubbles Bu to oppose the direction of the force that causes the ink to flow in the Z2 direction and presses the large bubbles Bu against the filter 116, compared to when the arrangement angle θ is less than 75 degrees.

[0094] Note that the values ​​shown in table T1 are merely examples. For example, at least one of the first flow rate and the second flow rate may be the same when the arrangement angle θ is 15 degrees and when it is 30 degrees. Also, the values ​​shown in table T1 may be different depending on the viscosity of the ink. Also, for example, the first flow rate may be the same when the arrangement angle θ is 30 degrees and when it is 0 degrees.

[0095] In addition, it is preferable that the circulation cleaning process including the first circulation cleaning operation and the second circulation cleaning operation shown in Table T1 is performed periodically. In this case, it is more preferable that the interval between the periodic circulation cleaning operations is shorter as the arrangement angle θ is larger.

[0096] 1-7: Circulation cleaning process The control unit 90 executes the circulation cleaning process of the head 10_1, the circulation cleaning process of the head 10_2, and the circulation cleaning process of the head 10_3 in parallel. For example, when the control unit 90 is a multi-processor and has three or more processors, each of the three processors of the control unit 90 may execute the circulation cleaning process of any one of the heads 10_1 to 10_3. When the control unit 90 has one processor, the circulation cleaning process of the head 10_1, the circulation cleaning process of the head 10_2, and the circulation cleaning process of the head 10_3 are executed by switching at regular intervals. The circulation cleaning process of the head 10_1 will be described with reference to FIG. 22. Note that the circulation cleaning process of the head 10_2 and the circulation cleaning process of the head 10_3 are almost the same as the circulation cleaning process of the head 10_1, and therefore the description thereof will be omitted.

[0097] FIG. 22 is a flow chart showing the contents of the circulatory cleaning process of the head 10_1.

[0098] In step S4, the control unit 90 acquires angle information DI_1 from the angle sensor 95_1.

[0099] Then, in step S6, the control unit 90 determines the first flow rate of the head 10_1 based on the table T1 and the arrangement angle θ indicated by the angle information DI_1. More specifically, the control unit 90 determines whether the arrangement angle θ1 indicated by the angle information DI_1 is registered in the table T1. If the arrangement angle θ1 indicated by the angle information DI_1 is registered in the table T1, the control unit 90 determines the first flow rate corresponding to the registered arrangement angle θ as the first flow rate of the head 10_1. On the other hand, if the arrangement angle θ1 indicated by the angle information DI_1 is not registered in the table T1, the control unit 90 executes an interpolation process based on the first flow rate corresponding to the arrangement angle θ close to the arrangement angle θ1 indicated by the angle information DI_1 among the multiple arrangement angles θ registered in the table T1, thereby determining it as the first flow rate of the head 10_1. The interpolation process may be, for example, linear interpolation or cubic spline interpolation.

[0100] After the process of step S6 is completed, in step S8, the control unit 90 executes a first circulatory cleaning operation for the multiple heads 10_1 of the head module 3_1 at the determined first flow rate. Note that, if the first flow rate corresponding to the arrangement angle θ1 indicated by the angle information DI_1 is 0 [g / sec], the first circulatory cleaning operation is omitted, and a second circulatory cleaning operation is executed as the circulatory cleaning process.

[0101] Then, in step S10, the control unit 90 determines the second flow rate of the head 10_1 based on the table T1 and the arrangement angle θ1 indicated by the angle information DI_1. More specifically, the control unit 90 determines whether the arrangement angle θ1 indicated by the angle information DI_1 is registered in the table T1. If the arrangement angle θ1 indicated by the angle information DI_1 is registered in the table T1, the control unit 90 determines the second flow rate corresponding to the registered arrangement angle θ as the second flow rate of the head 10_1. On the other hand, if the arrangement angle θ1 indicated by the angle information DI_1 is not registered in the table T1, the control unit 90 executes an interpolation process based on the second flow rate corresponding to the arrangement angle θ close to the arrangement angle θ1 indicated by the angle information DI_1 among the multiple arrangement angles θ registered in the table T1, thereby determining it as the second flow rate of the head 10_1. The interpolation process may be, for example, linear interpolation or cubic spline interpolation.

[0102] After completing the process of step S12, the control unit 90 executes the second circulation cleaning operation on the multiple heads 10_1 of the head module 3_1 at the second flow rate determined in step S10.

[0103] After completing the process of step S12, the control unit 90 ends the series of processes shown in FIG.

[0104] The control unit 90 may sequentially execute the circulation cleaning process of the head 10_1, the circulation cleaning process of the head 10_2, and the circulation cleaning process of the head 10_3.

[0105] A specific example of the circulation cleaning process will now be described.

[0106] For example, the arrangement angle θ1 of the head 10_1 indicated by the angle information DI_1 may be 5 degrees or more and 45 degrees or less. In this case, as an example, the arrangement angle θ1 of the head 10_1 is approximately 30 degrees. "Approximately 30 degrees" includes a case where the angle is exactly 30 degrees, as well as a case where the angle is considered to be 30 degrees considering manufacturing errors. Here, the Z2 direction, which is the flow direction of the ink passing through the filter 116 of the head 10_1, intersects with the z2 direction, which is the direction of gravity. The arrangement angle θ described above is the angle between the Z2 direction and the z2 direction in the head 10_1. Note that the flow direction of the ink passing through the filter 116 in the head 10_1 is an example of the "first direction". The arrangement angle θ1 of the head 10_1 is an example of the "first angle". Also, the head 10_1 is an example of the "first liquid ejection head". The filter 116 of the head 10_1 is an example of the "first filter".

[0107] The control unit 90 executes the above-mentioned circulation cleaning process for the head 10_1. The circulation cleaning process is an example of the above-mentioned "first circulation cleaning process." When performing a circulation cleaning process in which a second circulation cleaning operation is performed after the first circulation cleaning operation, the arrangement angle θ1 is preferably 10 degrees or more, and more preferably 15 degrees or more.

[0108] Moreover, the arrangement angle θ2 of the head 10_2 indicated by the angle information DI_2 may be larger than the first angle of the head 10_1 and may be equal to or smaller than 45 degrees. In this case, as an example, the arrangement angle θ2 of the head 10_2 is approximately 45 degrees. "Approximately 45 degrees" includes a case where the angle is exactly 45 degrees, as well as a case where the angle is considered to be 45 degrees considering manufacturing errors. Here, the Z2 direction, which is the flow direction of the ink passing through the filter 116 of the head 10_2, intersects with the z2 direction, which is the direction of gravity. The arrangement angle θ2 described above is the angle between the Z2 direction and the z2 direction in the head 10_2. The flow direction of the ink passing through the filter 116 in the head 10_2 is an example of the "second direction". The arrangement angle θ2 of the head 10_2 is an example of the "second angle". Moreover, the head 10_2 is an example of the "second liquid ejection head". The filter 116 provided in the head 10_2 is an example of a "second filter."

[0109] The control unit 90 performs the above-mentioned circulation cleaning process on the head 10_2. As is clear from the table T1 shown in Fig. 21, the first flow rate in the circulation cleaning process performed on the head 10_2 is smaller than the first flow rate in the circulation cleaning process performed on the head 10_1. Moreover, the second flow rate in the circulation cleaning process performed on the head 10_2 is larger than the second flow rate in the circulation cleaning process performed on the head 10_1.

[0110] Furthermore, the arrangement angle θ3 of the head 10_3 indicated by the angle information DI_3 may be approximately 0 degrees. "Approximately 0 degrees" includes cases where the angle is completely 0 degrees, as well as cases where the angle is considered to be 0 degrees in consideration of manufacturing errors. For example, "approximately 0 degrees" includes angles between 0 degrees and 3 degrees. Here, the Z2 direction, which is the flow direction of the ink passing through the filter 116 provided in the head 10_3, intersects with the z2 direction, which is the direction of gravity. The arrangement angle θ3 described above is the angle between the Z2 direction and the z2 direction in the head 10_3. Note that the flow direction of the ink passing through the filter 116 in the head 10_3 when the arrangement angle θ3 is approximately 0 degrees is an example of the "third direction". The arrangement angle θ of the head 10_3 when the arrangement angle θ3 is approximately 0 degrees is an example of the "third angle". Furthermore, the head 10_3 when the arrangement angle θ3 is approximately 0 degrees is an example of the "third liquid ejection head". The filter 116 provided in the head 10_3 when the arrangement angle θ3 is approximately 0 degree is an example of the “third filter”.

[0111] The control unit 90 executes the above-mentioned circulation cleaning process for the head 10_3. As is clear from the table T1 shown in FIG. 21, the first flow rate in the circulation cleaning process executed for the head 10_1 is smaller than the first flow rate in the circulation cleaning process executed for the head 10_3. Moreover, the second flow rate in the circulation cleaning process executed for the head 10_1 is larger than the second flow rate in the circulation cleaning process executed for the head 10_3. Note that, when executing the above-mentioned circulation cleaning process for the head 10_3, the control unit 90 may execute the second circulation cleaning operation without executing the first circulation cleaning operation. The circulation cleaning process in this case is an example of the "second circulation cleaning process".

[0112] Also, the arrangement angle θ3 of the head 10_3 indicated by the angle information DI_3 may be greater than 45 degrees. In this case, as an example, the arrangement angle θ3 of the head 10_3 is approximately 60 degrees. "Approximately 60 degrees" includes a case where the arrangement angle is exactly 60 degrees, as well as a case where the arrangement angle is considered to be 60 degrees in consideration of manufacturing errors. Here, the Z2 direction, which is the flow direction of the ink passing through the filter 116 provided in the head 10_3, intersects with the z2 direction, which is the direction of gravity. The arrangement angle θ3 described above is an angle between the Z2 direction and the z2 direction in the head 10_3. Note that the flow direction of the ink passing through the filter 116 in the head 10_3 when the arrangement angle θ3 is greater than 45 degrees is an example of the "fourth direction". The arrangement angle θ3 of the head 10_3 when the arrangement angle θ3 is 45 degrees or more is an example of the "fourth angle". Moreover, the head 10_3 when the arrangement angle θ3 is greater than 45 degrees is an example of a “fourth liquid ejecting head.” The filter 116 provided in the head 10_3 when the arrangement angle θ3 is greater than 45 degrees is an example of a “fourth filter.”

[0113] When the control unit 90 performs the above-mentioned circulation cleaning process on the head 10_3 whose arrangement angle θ3 is greater than 45 degrees, the control unit 90 performs the second circulation cleaning operation without performing the first circulation cleaning operation. The circulation cleaning process in this case is an example of the "second circulation cleaning process." When performing the second cleaning process, it is preferable that the arrangement angle θ3 of the head 10_3 is greater than 50 degrees.

[0114] 1-8: Advantages of the First Embodiment As described above, the liquid ejection device 100 according to the present embodiment includes one or more heads 10 as liquid ejection heads, a storage unit 93 as a liquid storage unit, a circulation mechanism 94, and a control unit 90. The head 10 has a filter 116 provided in the middle of a flow path that supplies liquid to a plurality of nozzles N that eject the liquid. The storage unit 93 stores the liquid to be supplied to the head 10. The circulation mechanism 94 circulates the liquid between the head 10 and the storage unit 93. The control unit 90 controls the circulation mechanism 94. The one or more heads 10 include a head 10_1 as a first liquid ejection head having a filter 116 as a first filter as the filter 116. The control unit 90 executes a first circulation cleaning process for the head 10_1, which executes a second circulation cleaning operation as a second circulation operation that circulates the liquid at a second flow rate that is greater than the first flow rate after executing a first circulation cleaning operation as a first circulation operation that circulates the liquid at a first flow rate.

[0115] Therefore, the liquid ejecting apparatus 100 can appropriately discharge the air bubbles from the upstream chamber 117A. More specifically, the liquid ejecting apparatus 100 integrates the large bubbles Bu and the small bubbles bb in the head 10_1 by a first circulation operation in which the liquid is circulated at a relatively small first flow rate. Thereafter, the liquid ejecting apparatus 100 causes the integrated new large bubbles Bu to pass through the first filter and be discharged from the head 10_1 by a second circulation operation in which the liquid is circulated at a relatively large second flow rate. As a result, the liquid ejecting apparatus 100 can suppress the small bubbles bb from remaining in the widened portion 117a1 on the upstream side of the first filter after the first circulation cleaning process.

[0116] Furthermore, in the liquid ejecting device 100 according to this embodiment, the first flow rate is a rate at which air bubbles of a predetermined size or larger do not pass through the filter 116. The second flow rate is a rate at which air bubbles of a predetermined size or larger pass through the filter 116.

[0117] Therefore, at the time of the first circulation cleaning operation, the liquid ejecting device 100 allows the small bubbles bb to remain in the widened portion 117a1, and then integrates these small bubbles bb into larger bubbles Bu, and then the second circulation cleaning operation is performed to expel the newly integrated large bubbles Bu from the head 10_1.

[0118] Furthermore, in the liquid ejecting device 100 according to this embodiment, the first flow rate is greater than the maximum flow rate of the liquid passing through the filter 116 while the head 10 serving as a liquid ejecting head is performing printing.

[0119] Therefore, the liquid ejecting device 100 can integrate the large bubbles Bu and the small bubbles bb in the head 10_1 by performing a first circulation cleaning operation that circulates liquid at a first flow rate that is greater than the circulation amount during printing or during print standby.

[0120] Furthermore, in the liquid ejecting device 100 according to this embodiment, after the second circulation cleaning operation has been performed in the first circulation cleaning process, the control unit 90 stops the circulation of the liquid by the circulation mechanism 94 for a predetermined time.

[0121] Therefore, even if small air bubbles bb are attached to the surface of the filter 116, the air bubbles will move vertically upward from the filter 116 due to buoyancy. As a result, the liquid ejection device 100 can remove the small air bubbles bb attached to the surface of the filter 116. In turn, the liquid ejection device 100 can prevent the filter 116 from becoming clogged with the small air bubbles bb, which would increase the pressure loss.

[0122] Furthermore, in the liquid ejecting device 100 according to this embodiment, the first direction, which is the flow direction of the liquid passing through the first filter, intersects with the direction of gravity.

[0123] Therefore, the liquid ejecting device 100 can remove the small air bubbles bb that are retained in the widened portion 117a1 on the upstream side of the filter 116 due to the first direction intersecting with the direction of gravity.

[0124] Furthermore, in the liquid ejecting device 100 according to this embodiment, the first angle formed between the first direction and the direction of gravity is equal to or smaller than 45 degrees.

[0125] For example, since it is necessary to tilt the head 10 of the liquid ejecting device 100 in accordance with the transport direction of the medium, etc., there are cases in which the filter 116 cannot be arranged horizontally. The liquid ejecting device 100 can remove small air bubbles bb that are retained in the widened portion 117a1 on the upstream side of the filter 116 due to the filter 116 not being arranged horizontally.

[0126] In the liquid ejecting device 100 according to this embodiment, the first angle is equal to or greater than 5 degrees.

[0127] For example, since it is necessary to tilt the head 10 of the liquid ejecting device 100 in accordance with the transport direction of the medium, etc., there are cases in which the filter 116 cannot be arranged horizontally. The liquid ejecting device 100 can remove small air bubbles bb that are retained in the widened portion 117a1 on the upstream side of the filter 116 due to the filter 116 not being arranged horizontally.

[0128] Furthermore, in the liquid ejecting device 100 according to this embodiment, the head 10 as one or more liquid ejecting heads includes a head 10_2 as a second liquid ejecting head having a second filter as the filter 116. A second angle, which is an angle between a second direction, which is a flow direction of the liquid passing through the second filter, and the direction of gravity, is larger than the first angle and is equal to or smaller than 45 degrees. The control unit 90 performs a first circulation cleaning process on the head 10_2. A first flow rate in the first circulation cleaning process performed on the head 10_2 is smaller than a first flow rate in the first circulation cleaning process performed on the head 10_1.

[0129] Therefore, the liquid ejecting device 100 can set the optimal first flow rate for moving the large bubble Bu inside the head 10.

[0130] Furthermore, in the liquid ejection apparatus 100 according to this embodiment, the second flow rate in the first circulation cleaning process performed on the head 10_2 as the second liquid ejection head is greater than the second flow rate in the first circulation cleaning process performed on the head 10_1 as the first liquid ejection head.

[0131] Therefore, the liquid ejecting apparatus 100 can set the optimal first flow rate for discharging the large bubbles Bu from the head 10.

[0132] Furthermore, in the liquid ejecting device 100 according to this embodiment, the one or more heads 10 include a head 10_3 as a third liquid ejecting head having a third filter as the filter 116. A third angle, which is an angle between a third direction, which is a flow direction of the liquid passing through the third filter, and the direction of gravity, is approximately 0 degrees. The control unit 90 executes a first circulation cleaning process on the third liquid ejecting head. A first flow rate in the first circulation cleaning process executed on the head 10_1 as the first liquid ejecting head is smaller than a first flow rate in the first circulation cleaning process executed on the head 10_3 as the third liquid ejecting head.

[0133] Therefore, the liquid ejecting device 100 can set the optimal first flow rate for moving the large bubble Bu inside the head 10.

[0134] Furthermore, in the liquid ejection apparatus 100 according to this embodiment, the second flow rate in the first circulation cleaning process performed on the head 10_1 as the first liquid ejection head is greater than the second flow rate in the first circulation cleaning process performed on the head 10_3 as the third liquid ejection head.

[0135] Therefore, the liquid ejecting apparatus 100 can set the optimal first flow rate for discharging the large bubbles Bu from the head 10.

[0136] Furthermore, in the liquid ejecting device 100 according to this embodiment, the one or more heads 10 include a head 10_3 serving as a third liquid ejecting head having a third filter as the filter 116. A third angle formed between the third direction, which is the flow direction of the liquid passing through the third filter, and the direction of gravity is approximately 0°. The control unit 90 executes a second circulation cleaning process for the head 10_3, which executes a second circulation cleaning operation without executing a first circulation cleaning operation.

[0137] Therefore, if small air bubbles bb are relatively unlikely to remain in the widened portion 117a1 upstream of the filter 116 due to the shape of the filter 116, the type of ink, etc., and their presence can be tolerated, the liquid ejection device 100 may perform a second circulation cleaning process that omits the first circulation cleaning operation.

[0138] Furthermore, in the liquid ejecting device 100 according to this embodiment, the one or more heads 10 include a head 10_3 serving as a fourth liquid ejecting head having a fourth filter as the filter 116. A fourth angle formed between a fourth direction, which is the flow direction of the liquid passing through the fourth filter, and the direction of gravity is greater than 45 degrees. The control unit 90 executes a second circulation cleaning process, which executes a second circulation cleaning operation without executing a first circulation cleaning operation, on the head 10_3.

[0139] Therefore, the liquid ejecting apparatus 100 does not need to perform the first circulation cleaning operation unnecessarily.

[0140] Furthermore, in the liquid ejecting device 100 according to this embodiment, the head 10 serving as a liquid ejecting head has a filter chamber 117 partitioned into an upstream chamber 117A and a downstream chamber 117B by a filter 116. The upstream chamber 117A has an air bubble chamber 114 that temporarily stores air bubbles, and an expanded portion 117a1 that is disposed between the air bubble chamber 114 and the filter 116 and has an area larger than that of the air bubble chamber 114 when viewed in the thickness direction of the filter 116.

[0141] Therefore, the liquid ejecting device 100 can discharge, from the head 10, the small air bubbles bb that remain in the widened portion 117a1.

[0142] In addition, in the liquid ejecting device 100 according to this embodiment, the maximum dimension d1 in the thickness direction of the widened portion 117a1 is smaller than the difference d2 between the outer periphery OC1 of the air bubble chamber 114 and the outer periphery OC2 of the widened portion 117a1 when viewed in the thickness direction.

[0143] Therefore, the liquid ejecting device 100 can discharge, from the head 10, the small air bubbles bb that remain in the widened portion 117a1.

[0144] Furthermore, the liquid ejection head cleaning method of the present embodiment is a cleaning method for head 10_1 as a first liquid ejection head, which has filter 116 as a first filter provided in the middle of a flow path that supplies liquid to a plurality of nozzles N that eject the liquid supplied from a storage section 93 as a first liquid storage section, and is characterized in that a first circulation cleaning process is performed on head 10_1, which performs a first circulation operation to circulate liquid between head 10_1 and storage section 93 at a first flow rate, and then a second circulation operation to circulate liquid at a second flow rate greater than the first flow rate.

[0145] Therefore, the liquid ejecting device 100 integrates the large bubbles Bu and the small bubbles bb in the head 10_1 by a first circulation operation in which the liquid is circulated at a relatively small first flow rate. After that, the liquid ejecting device 100 causes the newly integrated large bubbles Bu to pass through the first filter and be discharged from the head 10_1 by a second circulation operation in which the liquid is circulated at a relatively large second flow rate. As a result, the liquid ejecting device 100 can reduce the frequency of small bubbles bb occurring in the widened portion 117a1 on the upstream side of the first filter.

[0146] 2: Variations The above-mentioned embodiments can be modified in various ways. Specific modified embodiments are exemplified below. Two or more embodiments selected from the following examples can be combined as long as they are not mutually contradictory.

[0147] 2-1: First modified version In the first embodiment, the liquid ejection device 100 has three angle sensors 95, but the liquid ejection device 100 does not need to have the angle sensor 95. For example, the liquid ejection device 100 has a reception unit that receives operation information indicating a user's operation. The reception unit is, for example, a plurality of buttons. The reception unit receives operation information indicating the arrangement angles of head 10_1, head 10_2, and head 10_3. The control unit 90 identifies the arrangement angles of head 10_1, head 10_2, and head 10_3 based on the operation information received by the reception unit.

[0148] 2-2: Second variant In the above embodiment, the head 10 constitutes a line head, but the present invention is not limited to this configuration, and the head 10 may be configured as a serial type that reciprocates along the X-axis. The liquid ejecting device 100 in the second modified example has a head 10_1 in which the angle between the nozzle surface FN_1 and the horizontal plane SF is an arrangement angle θ1, and a head 10_2 in which the angle between the nozzle surface FN_2 and the horizontal plane SF is an arrangement angle θ2.

[0149] 2-3: Third variant The liquid ejection apparatus 100 exemplified in each of the above-mentioned embodiments can be adopted in various devices such as facsimile machines and copy machines, in addition to devices dedicated to printing. However, the use of the liquid ejection apparatus of the present invention is not limited to printing. For example, a liquid ejection apparatus that ejects a solution of a coloring material is used as a manufacturing device that forms a color filter of a liquid crystal display device. Also, a liquid ejection apparatus that ejects a solution of a conductive material is used as a manufacturing device that forms wiring and electrodes of a wiring board. [Explanation of symbols]

[0150] 3, 3_1, 3_2, 3_3...Head module, 9...Head fixing substrate, 9a...Mounting hole, 10, 10_1, 10_2, 10_3...Head, 11...Flow path structure, 11a, 11b, 11c, 11d...Connecting tube, 12...Wiring substrate, 12a...Hole, 12b...Opening, 12c...Connector, 13...Holder, 13a...Ink hole, 13b...Wiring hole, 14, 14_1, 14_2, 14_3, 14_4, 14_5...Head chip, 14a...Wiring member, 15...Fixing plate, 15a...Opening, 16...Base, 16a...Main body, 16b...Assembled substrate, 16c...Cover, 16d...Hole, 16e...Flange, 90...control unit, 91...memory unit, 92...transport mechanism, 93, 93_1, 93_2, 93_3...storage unit, 94, 94_1, 94_2, 94_3...circulation mechanism, 95, 95_1, 95_2, 95_3...angle sensor, 100...liquid ejection device, 110...flow path member, 112...ink introduction hole, 114...bubble chamber, 116...filter, 117...filter chamber, 117A...upstream chamber, 117a1...widening portion, 117B...downstream chamber, 118...flow path, 921...drum, 922...driving mechanism, 930...liquid supply source, 931...pump, 941...supply path, 942...recovery path, 943...flow mechanism, T1...table

Claims

1. one or more liquid ejection heads each having a filter provided in a flow path that supplies liquid to a plurality of nozzles that eject the liquid; a liquid storage section configured to store a liquid to be supplied to the liquid jet head; a circulation mechanism that circulates liquid between the liquid ejection head and the liquid storage section; A control unit for controlling the circulation mechanism; Equipped with the one or more liquid jet heads include a first liquid jet head having a first filter as the filter, the control unit executes a first circulation cleaning process on the first liquid ejecting head, the first circulation cleaning process being for executing a second circulation operation to circulate the liquid at a second flow rate that is greater than the first flow rate, after executing a first circulation operation to circulate the liquid at a first flow rate. A liquid ejection apparatus comprising:

2. the first flow rate is a flow rate at which air bubbles of a predetermined size or larger do not pass through the filter, The second flow rate is a flow rate at which bubbles having a size equal to or larger than the predetermined size pass through the filter. The liquid ejecting apparatus according to claim 1 .

3. the first flow rate is greater than a maximum flow rate of liquid passing through the filter while the liquid ejection head is printing; The liquid ejecting apparatus according to claim 1 .

4. the control unit stops the circulation of the liquid by the circulation mechanism for a predetermined time after performing the second circulation operation in the first circulation cleaning process. The liquid ejecting apparatus according to claim 1 .

5. A first direction, which is a flow direction of the liquid passing through the first filter, intersects with the direction of gravity. The liquid ejecting apparatus according to claim 1 .

6. A first angle between the first direction and the direction of gravity is 45 degrees or less. The liquid ejecting apparatus according to claim 5 .

7. The first angle is greater than or equal to 5 degrees. The liquid ejecting apparatus according to claim 6 .

8. the one or more liquid jet heads include a second liquid jet head having a second filter as the filter, a second angle between a second direction, which is a flow direction of the liquid passing through the second filter, and the direction of gravity is greater than the first angle and is equal to or less than 45 degrees; the control unit executes the first circulation cleaning process on the second liquid jet head, the first flow rate in the first circulation cleaning process performed on the second liquid jet head is smaller than the first flow rate in the first circulation cleaning process performed on the first liquid jet head; The liquid ejecting apparatus according to claim 6 .

9. the second flow rate in the first circulation cleaning process performed on the second liquid jet head is greater than the second flow rate in the first circulation cleaning process performed on the first liquid jet head; The liquid ejecting apparatus according to claim 8 .

10. the one or more liquid jet heads include a third liquid jet head having a third filter as the filter, a third angle between a third direction, which is a flow direction of the liquid passing through the third filter, and the direction of gravity is approximately 0 degrees; the control unit executes the first circulation cleaning process on the third liquid jet head, the first flow rate in the first circulation cleaning process performed on the first liquid jet head is smaller than the first flow rate in the first circulation cleaning process performed on the third liquid jet head; The liquid ejecting apparatus according to claim 6 .

11. the second flow rate in the first circulation cleaning process performed on the first liquid jet head is greater than the second flow rate in the first circulation cleaning process performed on the third liquid jet head; The liquid ejection apparatus according to claim 10 .

12. the one or more liquid jet heads include a third liquid jet head having a third filter as the filter, a third angle between a third direction, which is a flow direction of the liquid passing through the third filter, and the direction of gravity is approximately 0 degrees; the control unit performs a second circulation cleaning process on the third liquid jet head, the second circulation process being performed without performing the first circulation process. The liquid ejecting apparatus according to claim 6 .

13. the one or more liquid jet heads include a fourth liquid jet head having a fourth filter as the filter, a fourth angle between a fourth direction, which is a flow direction of the liquid passing through the fourth filter, and the direction of gravity is greater than 45 degrees; the control unit performs a second circulation cleaning process on the fourth liquid jet head, the second circulation process being performed without performing the first circulation process. The liquid ejecting apparatus according to claim 6 .

14. the liquid ejection head has a filter chamber partitioned into an upstream chamber and a downstream chamber by the filter, The upstream chamber has an air bubble chamber for temporarily storing air bubbles, and an expanded width portion that is disposed between the air bubble chamber and the filter and has an area larger than that of the air bubble chamber when viewed in a thickness direction of the filter. The liquid ejecting apparatus according to claim 1 .

15. a maximum dimension of the widened portion in the thickness direction is smaller than a difference between an outer periphery of the air bubble chamber and an outer periphery of the widened portion when viewed in the thickness direction; The liquid ejection apparatus according to claim 14 .

16. A cleaning method for a first liquid jet head having a first filter provided in a flow path that supplies liquid supplied from a first liquid storage portion to a plurality of nozzles that eject the liquid, the method comprising: a first circulation cleaning process is performed on the first liquid jet head, the first circulation process being for circulating liquid between the first liquid jet head and the first liquid storage section at a first flow rate, and then a second circulation process is performed on the first liquid jet head being for circulating liquid at a second flow rate that is greater than the first flow rate; A method for cleaning a liquid ejection head.

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