Liquid ejection device

Abstract

To solve such a problem that a large amount of ink has to be discharged in order to discharge sedimented ink in all distribution flow passages until there is no influence on a print result.SOLUTION: A liquid ejection device includes: a distribution flow passage that has a common portion commonly communicating with two or more common liquid chambers, a first branch portion branching from the common portion at a first position and communicating with a first common liquid chamber communicating with a first nozzle group, and a second branch portion branching from the common portion at a second position and communicating with a second common liquid chamber communicating with a second nozzle group; and a liquid inlet for introducing liquid into the distribution flow passage. The distance from the liquid inlet to the first position is longer than the distance from the liquid inlet to the second position. The device executes flushing processing in which more liquid is discharged from the first nozzle group than from the second nozzle group.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a liquid ejection apparatus. [Background technology]

[0002] Patent Document 1 discloses a liquid jet head having a distribution flow path that distributes ink to multiple head chips. In the liquid jet head disclosed in Patent Document 1, when ink is not ejected from the liquid jet head for a certain period of time, the coloring material such as pigment contained in the ink gradually settles in the distribution flow path, and settled ink with a high concentration of the coloring material may be generated. Therefore, as described in Patent Document 2, a technology is proposed to discharge the settled ink from the liquid jet head by performing a flushing process that discharges ink from each head chip. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-174392 A [Patent Document 2] JP 2008-201003 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when flushing is performed to discharge the settled ink from a liquid jet head having multiple head chips, the amount of discharged settled ink varies from head chip to head chip, and therefore, when discharging an equal amount of ink from each head chip in the flushing process, it is necessary to discharge a large amount of ink from the liquid jet head in order to discharge the settled ink from the liquid jet head. [Means for solving the problem]

[0005] In order to solve the above problems, a liquid ejection device according to a first preferred aspect of the present invention comprises a plurality of common liquid chambers including a first common liquid chamber communicating with a first nozzle group and a second common liquid chamber communicating with a second nozzle group, a distribution flow path having a common portion communicating in common with two or more of the plurality of common liquid chambers and a plurality of branch portions branching off from the common portion, and an inlet for introducing liquid into the distribution flow path, wherein the plurality of branch portions have a first branch portion branching off from the common portion at a first position and communicating with the first common liquid chamber, and a second branch portion branching off from the common portion at a second position and communicating with the second common liquid chamber, wherein a length along the distribution flow path from the inlet to the first position is longer than a length along the distribution flow path from the inlet to the second position, and a flushing process is performed in which an amount of liquid discharged from the first nozzle group is greater than an amount of liquid discharged from the second nozzle group.

[0006] In order to solve the above problems, a liquid ejecting device according to a second preferred aspect of the present invention includes a plurality of common liquid chambers including a first common liquid chamber communicating with a first nozzle group and a second common liquid chamber communicating with a second nozzle group, a distribution flow path having a common portion communicating in common with the plurality of common liquid chambers and a plurality of branch portions branching off from the common portion, and an inlet for introducing liquid into the distribution flow path, wherein the plurality of branch portions include a first branch portion communicating with the first common liquid chamber and a second branch portion communicating with the second common liquid chamber, a first flushing operation is performed to discharge liquid from at least the first nozzle group without discharging liquid from the second nozzle group, and a second flushing operation is performed to discharge liquid from at least the second nozzle group, and an amount of liquid discharged from the first nozzle group by the first flushing operation is greater than an amount of liquid discharged from the second nozzle group by the second flushing operation.

[0007] In addition, in order to solve the above problems, a liquid ejection device according to a third preferred aspect of the present invention comprises a first common liquid chamber communicating with a first nozzle group, a second common liquid chamber communicating with a second nozzle group, a distribution flow path for supplying liquid so as to distribute it to the first common liquid chamber and the second common liquid chamber, and an inlet for introducing liquid into the distribution flow path, wherein the length of the flow path from the inlet to the first common liquid chamber is longer than the length of the flow path from the inlet to the second common liquid chamber, and a flushing process is performed in which the amount of liquid ejected from the first nozzle group is greater than the amount of liquid ejected from the second nozzle group. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a partial configuration diagram of a liquid ejection apparatus 100 according to a first embodiment. [Diagram 2] FIG. 2 is an exploded perspective view of the liquid ejection head 14. [Diagram 3] FIG. 2 is an exploded perspective view of the liquid ejection head 14. [Figure 4] 4 is a plan view of the surface of the liquid ejecting unit G3 facing the medium M. FIG. [Diagram 5] FIG. 4 is an exploded perspective view of the liquid jet unit U3. [Figure 6] 5 is a plan view of the laminate of the filter portion 52, the communication member 54, and the wiring board 56, viewed from the head chip 70 side. [Figure 7] FIG. [Figure 8] 4 is a perspective view of a second flow path substrate 64 of the liquid distribution section 60 as viewed from the head chip 70 side. FIG. [Figure 9] FIG. [Figure 10] FIG. 4 is an explanatory diagram of flow paths formed inside the liquid distributor 60. [Figure 11] FIG. 13 is an explanatory diagram of a flow path formed inside a liquid distributor 60 according to a fourth modified example. [Figure 12] FIG. 13 is an explanatory diagram of a flow path formed inside a liquid distributor 60 according to a fifth modified example. [Figure 13] FIG. 13 is an explanatory diagram of a flow path formed inside a liquid distributor 60 according to a fifth modified example. [Figure 14] FIG. 13 is an explanatory diagram of a flow path formed inside a liquid distributor 60 according to a fifth modified example. [Figure 15] FIG. 13 is an explanatory diagram of flow paths formed inside a liquid distributor 60 according to a sixth modified example. [Figure 16] FIG. 13 is an explanatory diagram of a flow path formed inside a liquid distributor 60 according to a seventh modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments of 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.

[0010] For convenience, the following description will be given using the mutually intersecting X-axis, Y-axis, and Z-axis as appropriate. In the following description, one direction along the X-axis is the +X direction, and the direction opposite to the +X direction is the -X direction. Similarly, the mutually opposite directions along the Y-axis are the +Y direction and the -Y direction. In addition, the mutually opposite directions along the Z-axis are the +Z direction and the -Z direction. Here, typically, the Z-axis is a vertical axis, and the +Z direction corresponds to the downward direction in the vertical direction. However, the Z-axis does not have to be a vertical axis. In addition, the X-axis, Y-axis, and Z-axis are typically perpendicular to each other, but are not limited thereto, and may intersect at an angle within a range of 80° to 100°. In addition, in the figures described below, the direction in which the arrow indicating the X-axis shown in the figure faces is the +X direction. The same applies to the Y-axis and the Z-axis.

[0011] 1: First embodiment 1-1: Schematic configuration of liquid ejection device 1 is a partial configuration diagram of a liquid ejection device 100 according to a first embodiment of the present invention. The liquid ejection device 100 of the first embodiment is a liquid ejection device that ejects ink, which is an example of a liquid, onto a medium M such as printing paper, and includes a control unit 10, a transport mechanism 12, and a liquid ejection head 14. A liquid container 18 that stores ink I of multiple colors is attached to the liquid ejection device 100.

[0012] The control unit 10 comprehensively controls each element of the liquid ejection device 100. The control unit 10 includes one or more CPUs. However, the control unit 10 may include a programmable logic device such as an FPGA instead of or in addition to the CPU. Here, CPU is an abbreviation for Central Processing Unit, and FPGA is an abbreviation for field-programmable gate array. The control unit 10 also includes a memory. The memory includes one or both of a volatile memory such as a RAM (Random Access Memory) and a non-volatile memory such as a ROM (Read Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), or a PROM (Programmable ROM).

[0013] The transport mechanism 12 transports the medium M in the Y direction under the control of the control unit 10. The control unit 10 also transmits to the liquid ejection head 14 a print signal for selecting a nozzle N to be ejected from among the multiple nozzles N based on image data to be printed on the medium M, a drive signal for driving a piezoelectric element 732 described later, a power supply voltage, and the like. The liquid ejection head 14 then ejects the ink I supplied from the liquid container 18 toward the medium M based on the print signal and the like transmitted from the control unit 10. In this manner, a printing operation is performed to form a desired image on the medium M. The liquid ejection head 14 of the first embodiment is a line head that is elongated in the X direction intersecting with the Y direction. Note that the direction perpendicular to the XY plane, i.e., the plane parallel to the surface of the medium M, is hereinafter referred to as the Z direction. The ejection direction of the ink I by the liquid ejection head 14 corresponds to the Z direction.

[0014] 2 and 3 are exploded perspective views of the liquid jet head 14. As illustrated in FIGS. 2 and 3, the liquid jet head 14 of the first embodiment is configured to include a flow path structure G1, a flow path control unit G2, and a liquid jet unit G3. Schematically, the flow path control unit G2 is installed between the flow path structure G1 and the liquid jet unit G3. That is, the flow path structure G1, the flow path control unit G2, and the liquid jet unit G3 overlap each other when viewed in the Z direction. The liquid jet unit G3 is a structure in which six liquid jet units U3 are accommodated and supported in a housing 142.

[0015] FIG. 4 is a plan view of the surface of the liquid ejection unit G3 facing the medium M. As illustrated in FIG. 4, six liquid ejection units U3 are arranged along the X direction. Each liquid ejection unit U3 has a plurality of head chips 70 arranged along the X direction. Each head chip 70 includes a plurality of nozzles N. Each of the plurality of nozzles N ejects ink I. The plurality of nozzles N included in one head chip 70 are arranged in two rows along the W direction inclined at a predetermined angle with respect to the X direction and the Y direction. One row of nozzles N constitutes a nozzle group Ns. Therefore, one head chip 70 includes a plurality of nozzle groups Ns. Ink I is supplied in parallel to each head chip 70 of the liquid ejection unit U3. In the following, for the sake of simplicity of explanation, it is assumed that two systems of ink I are supplied in parallel to each head chip 70.

[0016] 2 and 3 is an element that controls the opening and closing of the flow paths of the liquid jet head 14 and the pressure within the flow paths, and is configured to include six flow path control units U2 corresponding to different liquid jet units U3. There is a one-to-one correspondence between the flow path control units U2 and the liquid jet units U3. Each flow path control unit U2 controls the opening and closing and pressure of the two systems of ink I flow paths distributed by the flow path structure G1 to each liquid jet unit U3.

[0017] The liquid ejection unit G3 ejects the ink I of each system from the nozzles N via the flow path control unit G2. As illustrated in Fig. 2, two supply ports SI3 are formed in the surface of each liquid ejection unit U3 of the liquid ejection unit G3 facing the flow path control unit G2. When the flow path control unit G2 and the liquid ejection unit G3 are fixed to each other, each supply port SI3 of each liquid ejection unit U3 is inserted into each outlet DI2 of the flow path control unit U2. Therefore, the ink I of each system is supplied in parallel from the outlet DI2 of the flow path control unit U2 to the two supply ports SI3 of each liquid ejection unit U3.

[0018] Fig. 5 is an exploded perspective view of any one of the liquid ejection units U3. As illustrated in Fig. 5, the liquid ejection unit U3 includes a filter unit 52, a communication member 54, a wiring board 56, a liquid distribution unit 60, six head chips 70, and a fixing plate 58. Between the filter unit 52 and the six head chips 70, the communication member 54, the wiring board 56, and the liquid distribution unit 60 are installed in this order.

[0019] As can be understood from the above explanation, the flow path control section G2 including the flow path control unit U2, the filter section 52, the communicating member 54, and the wiring board 56 are installed in this order between the flow path structure G1 and the liquid distribution section 60, which overlap each other in a planar view.

[0020] The filter unit 52 is an element that removes air bubbles and foreign matter contained in each ink I supplied from the flow path control unit G2. As illustrated in FIG. 5, the filter unit 52 includes two filters 526 corresponding to each ink I.

[0021] Fig. 6 is a plan view of the laminate of the filter section 52, the communication member 54, and the wiring board 56, viewed from the head chip 70 side. For convenience, illustration of the liquid distribution section 60 and the head chip 70 is omitted in Fig. 6. As illustrated in Fig. 6, the filter section 52 has two outlets 528 corresponding to each ink I formed therein.

[0022] 5 connects each outlet 528 of the filter section 52 to the liquid distribution section 60. As illustrated in Fig. 6, the communication member 54 is formed with a plurality of through holes 542 corresponding to each outlet 528 of the filter section 52. Specifically, each through hole 542 is located at each corner of the communication member 54 in a plan view.

[0023] 5 is a board on which wiring is formed for transmitting print signals, drive signals, and power supply voltage to each head chip 70. It is also possible to mount electronic circuits on the wiring board 56 for generating print signals, drive signals, and power supply voltage.

[0024] The liquid distributor 60 in FIG. 5 distributes each of the two systems of ink I supplied via each through-hole 542 of the communication member 54 into six systems corresponding to each head chip 70.

[0025] FIG. 7 is an exploded perspective view of the liquid distribution section 60. The outline of the wiring board 56 laminated on the first flow path board 62 is conveniently illustrated by a dashed line in FIG. 7. As illustrated in FIG. 7, inlets 60A corresponding to the inks I are formed at two diagonal corners of the first flow path board 62 corresponding to the notches 562 of the wiring board 56. As illustrated in FIG. 5, when the wiring board 56 is sandwiched between the communicating member 54 and the liquid distribution section 60, the communicating member 54 is pressed toward the wiring board 56, so that the first flow path board 62 and the communicating member 54 come into close contact with each other inside the notches 562 of the wiring board 56. As a result, the through holes 542 of the communicating member 54 and the inlets 60A of the liquid distribution section 60 are mutually communicated. That is, the inks I of the two systems that have passed through the filter section 52 and the communicating member 54 are supplied in parallel to the inlets 60A of the liquid distribution section 60.

[0026] As illustrated in FIG. 7, grooves 642 corresponding to the distribution channels Q1 and Q2 are formed on the surface of the second flow path substrate 64 facing the first flow path substrate 62. The distribution channels Q1 and Q2 are formed by blocking the grooves 642 on the surface of the second flow path substrate 64 with the surface of the first flow path substrate 62 facing the second flow path substrate 64. In the example illustrated in FIG. 7, the distribution channels Q1 and Q2 are formed by the grooves 642 on the surface of the second flow path substrate 64, but a configuration in which the distribution channels Q1 and Q2 are formed by grooves formed on the surface of the first flow path substrate 62 facing the second flow path substrate 64 may also be employed. A configuration in which the distribution channels Q1 and Q2 are formed by a combination of grooves formed on the respective opposing surfaces of the first flow path substrate 62 and the second flow path substrate 64 may also be employed.

[0027] As exemplified above, each of the distribution channels Q1 and Q2 is formed between the first flow path substrate 62 and the second flow path substrate 64. That is, each of the distribution channels Q1 and Q2 is a channel extending along the XY plane.

[0028] Fig. 8 is a perspective view of the second flow path substrate 64 of the liquid distribution unit 60 as viewed from the head chip 70 side. For the sake of convenience, the contour lines of each head chip 70 are illustrated by dashed lines in Fig. 8. As illustrated in Fig. 8, in the second flow path substrate 64, two outlets 60B corresponding to the two systems of ink I are formed for each of the six head chips 70.

[0029] Each of the six head chips 70 in FIG. 5 ejects from each nozzle N two systems of ink I supplied from each outlet 60B of the liquid distributor 60.

[0030] Fig. 9 is a cross-sectional view of one head chip 70. As illustrated in Fig. 9, in the head chip 70 of the first embodiment, a pressure chamber forming substrate 72 and a vibration plate 73 are laminated on one surface of a flow path forming substrate 71, and a nozzle plate 74 and a compliance portion 75 are provided on the other surface. A plurality of nozzles N are formed in the nozzle plate 74. As can be understood from Fig. 9, in one head chip 70, structures corresponding to two rows of nozzles N are formed in a substantially line symmetrical manner, so the structure of the head chip 70 will be described below by focusing on one row of nozzles N for the sake of convenience.

[0031] The flow path forming substrate 71 is a flat plate material that constitutes a flow path of the ink I. In the flow path forming substrate 71 of the first embodiment, an opening 712, a first communication flow path 714, a supply flow path 716, and a second communication flow path 718 are formed. The opening 712 and the first communication flow path 714 communicate with each other. The first communication flow path 714 and the supply flow path 716 communicate with each other. The supply flow path 716 and a pressure chamber C described below communicate with each other. The pressure chamber C and the second communication flow path 718 communicate with each other. The supply flow path 716, the pressure chamber C, and the second communication flow path 718 are formed for each nozzle N. The supply flow path 716, the pressure chamber C, and the second communication flow path 718 form an individual flow path IP. The opening 712 and the first communication flow path 714 are continuous across a plurality of nozzles N that eject one system of ink I. The pressure chamber forming substrate 72 is a flat plate material in which a plurality of openings 722 corresponding to the different nozzles N are formed. The flow passage forming substrate 71 and the pressure chamber forming substrate 72 are formed of, for example, a silicon single crystal substrate.

[0032] 9 is a mechanism for absorbing pressure fluctuations in the flow paths of the head chip 70, and includes a sealing plate 752 and a support 754. The sealing plate 752 is a flexible film-like member, and the support 754 fixes the sealing plate 752 to the flow path forming substrate 71 such that the openings 712 and the first communication flow paths 714 of the flow path forming substrate 71 are closed.

[0033] A vibration plate 73 is provided on the surface of the pressure chamber forming substrate 72 in Fig. 9 opposite to the flow path forming substrate 71. The vibration plate 73 is a flat member that can vibrate elastically, and is composed of a laminate of an elastic film made of an elastic material such as silicon oxide and an insulating film made of an insulating material such as zirconium oxide. As can be seen from Fig. 9, the vibration plate 73 and the flow path forming substrate 71 face each other with a gap between them inside each opening 722 formed in the pressure chamber forming substrate 72. The space between the flow path forming substrate 71 and the vibration plate 73 inside each opening 722 functions as a pressure chamber C that applies pressure to the ink I. The multiple pressure chambers C are arranged along the W direction.

[0034] A plurality of piezoelectric elements 732 corresponding to different nozzles N are formed on the surface of the vibration plate 73 opposite to the pressure chamber forming substrate 72. Each piezoelectric element 732 is a laminate having a piezoelectric body interposed between electrodes facing each other. When a drive signal is supplied, the piezoelectric elements 732 deform, causing the vibration plate 73 to vibrate, thereby fluctuating the pressure in the pressure chamber C and causing the ink I in the pressure chamber C to be ejected from the nozzle N. Each piezoelectric element 732 is sealed and protected by a protective plate 76 fixed to the vibration plate 73.

[0035] 9, a support 77 is fixed to the flow path forming substrate 71 and the protective plate 76. The support 77 is integrally formed, for example, by molding a resin material. In the support 77 of the first embodiment, a space 772 communicating with the opening 712 of the flow path forming substrate 71 and a supply port 774 communicating with the space 772 are formed. A common liquid chamber CR is formed by the space 772, the opening 712, and the first communication flow path 714. The common liquid chamber CR extends along the W direction and is continuous across the multiple nozzles N. In addition, since the multiple head chips 70 are aligned in the X direction, the multiple common liquid chambers CR are also aligned in the X direction.

[0036] Each supply port 774 communicates with each outlet 60B of the liquid distribution unit 60. Therefore, the ink I of each system after distribution by the liquid distribution unit 60 is supplied from the outlet 60B via the supply port 774 of the head chip 70 to the common liquid chamber CR and stored therein. The ink I stored in the common liquid chamber CR is distributed and filled into each pressure chamber C by the multiple supply flow paths 716, and is ejected from each pressure chamber C through the second communication flow path 718 and the nozzle N to the outside.

[0037] 9, an end of a wiring board 78 is joined to the vibration plate 73. The wiring board 78 is a flexible board on which wiring is formed for transmitting print signals, drive signals, power supply voltages, and the like to each piezoelectric element 732, and protrudes toward the wiring board 56 side through openings formed in the protective plate 76 and the support body 77.

[0038] 8, openings 60C corresponding to the wiring boards 78 of the head chips 70 are formed in the liquid distribution section 60. The wiring boards 78 of the head chips 70 protrude toward the wiring board 56 through the respective openings 60C of the liquid distribution section 60, and the ends opposite the head chips 70 are connected to the wiring board 56. Driving signals and power supply voltages are supplied from the wiring board 56 to the piezoelectric elements 732 of the head chips 70 through the respective wiring boards 78.

[0039] 1 to 9 is merely an example. For example, liquid ejecting device 100 may include any number of head chips 70, such as two or more. In addition, the relative position of inlet 60A with respect to multiple outlets 60B may be any position.

[0040] (Regarding the routing of distribution flow path Q) FIG. 10 is an explanatory diagram of the flow paths formed inside the liquid distribution unit 60. For the sake of simplicity, FIG. 10 shows only the above-mentioned distribution flow path Q1 out of the two distribution flow paths Q formed inside the liquid distribution unit 60 of the first embodiment. For convenience of explanation, the W direction and the X direction are perpendicular to each other in FIG. 10, but as can be understood from FIG. 4 and the like, in this embodiment, the W direction and the X direction actually intersect so as not to be perpendicular to each other. This point is the same for FIG. 11 and subsequent figures. Of course, as shown in FIG. 10, the W direction and the X direction may actually be perpendicular to each other.

[0041] The distribution flow channel Q1 distributes ink I supplied to one inlet 60A to six outlets 60B corresponding to different head chips 70. Specifically, the distribution flow channel Q1 has one trunk part EA extending in the X direction. The trunk part EA has a common part CP that is in communication with two or more common liquid chambers CR among a plurality of common liquid chambers CR[1]-CR[6] described below. The distribution flow channel Q1 is also configured to include six branch parts FA that branch off from different positions LC of the common part CP. Specifically, the six branch portions FA include a branch portion FA[1] that branches from the common portion CP at a position LC[1], a branch portion FA[2] that branches from the common portion CP at a position LC[2], a branch portion FA[3] that branches from the common portion CP at a position LC[3], a branch portion FA[4] that branches from the common portion CP at a position LC[4], a branch portion FA[5] that branches from the common portion CP at a position LC[5], and a branch portion FA[6] that branches from the common portion CP at a position LC[6]. In this embodiment, as shown in FIG. 10, the positions LC[1] and LC[2] arranged at one end of the common portion CP are the same position. Similarly, the positions LC[5] and LC[6] arranged at the other end of the common portion CP are the same position. That is, the branch portion FA[1] and the branch portion FA[2] individually branch from the common portion CP at the same position LC[1]=LC[2]. The branch portions FA[5] and FA[6] branch off individually from the common portion CP at the same position LC[5]=LC[6].

[0042] The common portion CP of the distribution flow channel Q1 is connected to an inlet 60A, and each end of the six branch portions FA[1] to FA[6] of the distribution flow channel Q1 is connected to an outlet 60B. The outlet 60B is connected to the common liquid chambers CR[1] to CR[6] shown by dashed lines in FIG. 10. The six branch portions FA[1] to FA[6] correspond one-to-one to the six common liquid chambers CR[1] to CR[6]. Here, the common portion CP that is connected to the two or more common liquid chambers CR described above is a portion of the distribution flow channel Q1 where ink flows from the inlet 60A to two or more outlets 60B, specifically, the portion of the distribution flow channel Q1 from position LC[1]=LC[2] to position LC[5]=LC[6]. For example, the part of the trunk EA in the +X direction from LC[1]=LC[2] is not the common part CP because it is a part where ink flows only toward one outlet 60B that communicates with the branch part FA[1]. Similarly, the part of the trunk EA in the -X direction from LC[5]=LC[6] is not the common part CP.

[0043] As described above with reference to FIG. 9, the common liquid chamber CR communicates with the individual flow paths IP. Each of the individual flow paths IP communicates with each of the nozzles N. That is, the common liquid chamber CR communicates with the nozzle group Ns having the nozzles N through the individual flow path group IPs having the individual flow paths IP. In FIG. 10, the nozzle group Ns is indicated by a dashed line. In FIG. 10, the six common liquid chambers CR[1]-CR[6] communicate with the six individual flow path groups IPs[1]-IPs[6]. The six individual flow path groups IPs[1]-IPs[6] communicate with the six nozzle groups Ns[1]-Ns[6]. The six common liquid chambers CR[1]-CR[6] and the six individual flow path groups IPs[1]-IPs[6] correspond one-to-one to each other. The six individual flow path groups IPs[1] to IPs[6] and the six nozzle groups Ns[1] to Ns[6] have a one-to-one correspondence with each other.

[0044] The inlet 60A is located between the position LC[3] and the position LC[4] in the X-axis direction. The position LC[2] is located in the +X direction relative to the position LC[3]. The position LC[5] is located in the -X direction relative to the position LC[4]. That is, the length from the inlet 60A to the position LC[2] along the distribution flow path Q1 is longer than the length from the inlet 60A to the position LC[3] along the distribution flow path Q1. The length from the inlet 60A to the position LC[5] along the distribution flow path Q1 is longer than the length from the inlet 60A to the position LC[4] along the distribution flow path Q1.

[0045] The branch portion FA[3] branches off individually from the common portion CP at position LC[3] between position LC[2], which is one end of the common portion CP, and the inlet 60A. The branch portion FA[4] branches off individually from the common portion CP at position LC[4] between position LC[5], which is the other end of the common portion CP, and the inlet 60A. In other words, the number of branch portions FA branching off from the common portion CP between position LC[2] and the inlet 60A and the number of branch portions FA branching off from the common portion CP between position LC[5] and the inlet 60A are both one, and are the same number.

[0046] The ink I[1] that passes through the branch portion FA[1] passes through the common liquid chamber CR[1] and the individual flow path group IPs[1] and is discharged from the nozzle group Ns[1]. The ink I[2] that passes through the branch portion FA[2] passes through the common liquid chamber CR[2] and the individual flow path group IPs[2] and is discharged from the nozzle group Ns[2]. The ink I[3] that passes through the branch portion FA[3] passes through the common liquid chamber CR[3] and the individual flow path group IPs[3] and is discharged from the nozzle group Ns[3]. The ink I[4] that passes through the branch portion FA[4] passes through the common liquid chamber CR[4] and the individual flow path group IPs[4] and is discharged from the nozzle group Ns[4]. The ink I[5] that passes through the branch portion FA[5] passes through the common liquid chamber CR[5] and the individual flow path group IPs[5] and is discharged from the nozzle group Ns[5]. The ink I[6] that passes through the branch portion FA[6] passes through the common liquid chamber CR[6] and the individual flow path group IPs[6], and is discharged from the nozzle group Ns[6].

[0047] In addition, in Figure 10, the flow path width of the main trunk EA is shown as being sufficiently larger than the flow path width of the portion of the branching portion FA along the W direction, but in reality, they are almost the same, and the cross-sectional area A1 of the main trunk EA and the cross-sectional area A2 of the portion of the branching portion FA along the W direction satisfy the relationship cross-sectional area A1 < cross-sectional area A2 × 2.

[0048] (Regarding normal flushing process) The liquid ejecting apparatus 100 of this embodiment is capable of executing two types of flushing processes: a normal flushing process and a flushing process for eliminating sedimentation. First, the normal flushing process will be described.

[0049] During printing operations, the frequency of use of each of the multiple nozzles N, i.e., the number of times ink is ejected, varies. Some nozzles N are used frequently, while other nozzles N are hardly used at all. In nozzles N that are used less frequently, the viscosity of the ink increases. As a result, clogging occurs, and the quality of the printed image deteriorates.

[0050] In order to prevent such inconvenience, the control unit 10 performs flushing of the less frequently used nozzles N as a normal flushing process after the printing operation is completed. Here, flushing refers to a series of operations in which a drive signal is supplied to the piezoelectric element 732 to generate a pressure fluctuation in the ink in the pressure chamber C, thereby ejecting ink from the nozzle N toward a waste liquid container (not shown), and ink is supplied from the liquid container 18 to the pressure chamber C in association with the ejection. In other words, flushing refers to discharging ink from the liquid ejection head 14 from the nozzle N as waste liquid that does not contribute to image formation on the medium M. There are no particular limitations on the signal shape of the drive signal as long as it ejects ink from the nozzle N.

[0051] Furthermore, the normal flushing process may be performed after a wiping operation is performed to wipe the surface of the nozzle plate 74 with a wiping member such as a cloth (not shown) in order to remove foreign matter and ink adhering to the surface of the nozzle plate 74. By performing flushing after the wiping operation, the meniscus of ink in the nozzle N can be formed normally.

[0052] (About settling ink) Here, the settled ink in the distribution flow channel Q and the common liquid chamber CR will be described. If ink is not discharged from the nozzle N for a long period of time after the previous printing operation, the normal flushing process described above, or the cleaning operation described below, which discharges ink from the nozzle N, the state in which no ink flow occurs in the distribution flow channel Q and the common liquid chamber CR continues. Then, coloring material such as pigment particles may gradually settle in the common liquid chamber CR and the distribution flow channel Q. As a result, a layer with a high concentration of coloring material and an excessively dark color (hereinafter referred to as settled ink) is generated on the bottom surface of the distribution flow channel Q and the common liquid chamber CR. If a printing operation is performed with such settled ink present in the distribution flow channel Q, density unevenness will occur in the image. Therefore, if ink is not discharged from the nozzle N for a long period of time, it is desirable to discharge all settled ink in the distribution flow channel Q and the common liquid chamber CR before performing the printing operation.

[0053] In order to discharge the settled ink from within the distribution flow paths Q and the common liquid chamber CR, it is possible to carry out suction cleaning or pressure cleaning on the liquid ejecting head 14. Suction cleaning is a cleaning method in which, in order to expel foreign matter such as air bubbles that have entered the liquid jet head 14, a concave-shaped cap (not shown), which can move relative to the liquid jet head 14, is abutted against the nozzle forming surface of the liquid jet head 14 on which the multiple nozzles N are formed, forming a closed space in which the multiple nozzles N are open.A negative pressure generating mechanism, such as a pump, connected inside the cap is then driven to create negative pressure in the closed space, thereby expelling ink from the liquid jet head 14 through the multiple nozzles N. Pressurized cleaning is a cleaning method in which ink is discharged from multiple nozzles N by pressurizing the liquid container 18, for example, upstream of the pressure chamber C, using a pressure mechanism such as a diaphragm pump (not shown) in order to expel foreign matter such as air bubbles that have entered the liquid ejection head 14. However, suction cleaning and pressure cleaning generally involve a large amount of ink being discharged from the liquid ejection head 14 through the multiple nozzles N, consuming more ink than the volume of the flow path downstream of the inlet 60A, which creates the problem that after all the settled ink has been discharged, non-settled ink is also discharged through the nozzles N.

[0054] (Issues with the flushing process for eliminating sedimentation in the comparative example) Therefore, in order to discharge the settled ink in the distribution flow paths Q and the common liquid chamber CR, it is conceivable to carry out a flushing process that consumes a relatively small amount of ink instead of cleaning. This flushing process is a flushing process for eliminating sedimentation that is carried out in response to an instruction from the control unit 10 when the operation of discharging ink from the nozzles N has not been carried out for a predetermined period of time since the previous operation. This predetermined period is desirably set to the time until settled ink occurs, and is, for example, 48 hours, but may also be 24 hours or 3 hours. Next, a flushing process for eliminating sedimentation as a comparative example (hereinafter, sometimes simply referred to as a comparative flushing process) and the problems associated with the comparative flushing process will be described.

[0055] In the flushing process of the comparative example, in order to discharge the ink that has settled in the distribution flow path Q and the common liquid chamber CR, the nozzle groups Ns[1] to Ns[6] are flushed to discharge an approximately equal amount of ink for the same period of time. In this embodiment, "the amount of ink discharged from each of the nozzle groups Ns by flushing is approximately equal to each other" means that, for example, the number of nozzles N for which flushing is performed is the same for each of the six nozzle groups Ns, the signal shape of the drive signal supplied to the piezoelectric element 732 of each nozzle group Ns to perform flushing is the same, and further, the number of times that ink is discharged from the nozzles N of each nozzle group Ns is the same, so that the amounts of ink are theoretically equal to each other, with the design error being within the allowable range. As an error, an error of about ±10% is allowed with respect to the average amount of ink discharged from each nozzle group Ns when flushing is performed on each nozzle group Ns under the same conditions described above. In this way, during the flushing process of the comparative example, the same amount of ink is discharged from each nozzle group Ns, so the flow rates per unit time of the ink I[1] to I[6] flowing through each of the branch portions FA[1] to FA[6] are approximately equal to each other.

[0056] Here, the problem in the flushing process of the comparative example will be described. For example, when focusing on the branch portions FA[1] to FA[3], as shown in Fig. 10, the distance from the inlet 60A to the branch portions FA[1] and FA[2] is longer than the distance from the inlet 60A to the branch portion FA[3]. In other words, immediately before the flushing process of the comparative example is performed, the amount of settled ink present in each of the portions from the inlet 60A to the outlet 60B connected to the branch portion FA[1] and the portions from the inlet 60A to the outlet 60B connected to the branch portion FA[2] is greater than the amount of settled ink present in the portion from the inlet 60A to the outlet 60B connected to the branch portion FA[3]. Therefore, when the flow rates per unit time of the inks I[1] to I[3] flowing through the branch portions FA[1] to FA[3] are approximately equal to each other as in the flushing process of the comparative example, when all the settled ink is discharged from the branch portion FA[3], all the settled ink present in each of the branch portions FA[1] and FA[2] is not yet discharged. As a result, even after all the settled ink is discharged from the branch portion FA[3], the flushing process of the comparative example needs to be continued until all the settled ink present in each of the branch portions FA[1] and FA[2] is discharged, so that the ink that has not settled (hereinafter, sometimes referred to as normal ink) flowing in from the inlet 60A may flow into the branch portion FA[3] and be discharged wastefully from the nozzle group Ns[3]. The same is true for branch portions FA[4] to FA[6]. Even after all the settled ink has been discharged from branch portion FA[4], the flushing process of the comparative example continues until all the settled ink in each of branch portions FA[5] and FA[6] has been discharged, resulting in normal ink flowing in from the inlet 60A being wasted from nozzle group Ns[4].

[0057] Next, another problem in the flushing process of the comparative example will be described. During the flushing process of the comparative example, if the flow rate per unit time of each of the inks I[1] to I[6] flowing through each of the branch portions FA[1] to FA[6] is a, the flow rate per unit time of the ink I[3] moving from the position LC[3] to the branch portion FA[3] is a. On the other hand, the flow rate per unit time of the ink I moving from the position LC[3] to the position LC[1]=LC[2], not to the branch portion FA[3], is 2a, which is the total amount of the ink I[1] and I[2]. Therefore, the flow rate of the ink I moving from the position LC[3] to the position LC[1]=LC[2] is faster than the flow rate of the ink I[3] moving from the position LC[3] to the branch portion FA[3]. Since the settled ink tends to move along with the flow with a faster flow rate, the settled ink in the common part CP flows toward the position LC[1]=LC[2] more than toward the branch part FA[3]. In other words, in the flushing process of the comparative example, when attempting to discharge all the settled ink in the flow path downstream of the inlet 60A, the amount of settled ink discharged from each of the nozzle groups Ns[1] and Ns[2] is greater than the amount of settled ink discharged from the nozzle group Ns[3]. Therefore, in the flushing process of the comparative example, normal ink is wasted from the nozzle group Ns[3] while the settled ink is being discharged from each of the nozzle groups Ns[1] and Ns[2].

[0058] Of the ink I flowing from position LC[3] to position LC[1]=LC[2], the amount of ink I[2] flowing toward the branch portion FA[2] and the amount of ink I[1] flowing toward the branch portion FA[1] are both equal to a. As a result, the amount of settled ink flowing from the common portion CP toward the branch portion FA[1] is approximately equal to the amount of settled ink flowing from the common portion CP toward the branch portion FA[2].

[0059] A similar difference in flow speed occurs at branch portions FA[4] to FA[6], so that during the flushing process of the comparative example, normal ink is unnecessarily discharged from nozzle group Ns[4] while settled ink is being discharged from each of nozzle groups Ns[5] and Ns[6].

[0060] 1-2: Contents of the flushing process

[0061] (Flushing process for eliminating sedimentation according to this embodiment) Here, the flushing process for eliminating sedimentation according to this embodiment (hereinafter, sometimes referred to as the flushing process of this embodiment) will be described. In the flushing process of the comparative example described above, normal ink is unnecessarily discharged from the nozzle groups Ns[3] and Ns[4], so in the flushing process of this embodiment, the control unit 10 executes flushing for each nozzle group Ns so that the discharge amount of the ink I[1] discharged from the nozzle group Ns[1], the discharge amount of the ink I[2] discharged from the nozzle group Ns[2], the discharge amount of the ink I[5] discharged from the nozzle group Ns[5], and the discharge amount of the ink I[6] discharged from the nozzle group Ns[6] are each greater than the discharge amount of the ink I[3] discharged from the nozzle group Ns[3] and the discharge amount of the ink I[4] discharged from the nozzle group Ns[4].

[0062] It is also preferable that the discharge amount of ink I[1] is approximately equal to the discharge amount of ink I[2]. It is also preferable that the discharge amount of ink I[5] is approximately equal to the discharge amount of ink I[6]. Also, it is preferable that the total discharge amount of ink I[1] and ink I[2] is approximately equal to the total discharge amount of ink I[5] and ink I[6]. In addition, in the flushing process for eliminating sedimentation, the amount of ink discharged from the nozzle group Ns[1] is greater than the amount of ink discharged from each nozzle group Ns in a normal flushing process.

[0063] The nozzle group Ns[1] is an example of a "first nozzle group". The nozzle group Ns[3] is an example of a "second nozzle group". The nozzle group Ns[2] is an example of a "third nozzle group". The nozzle group Ns[5] is an example of a "fourth nozzle group". The nozzle group Ns[6] is an example of a "fifth nozzle group". The common liquid chamber CR[1] is an example of a "first common liquid chamber". The common liquid chamber CR[3] is an example of a "second common liquid chamber". The common liquid chamber CR[2] is an example of a "third common liquid chamber". The common liquid chamber CR[5] is an example of a "fourth common liquid chamber". The common liquid chamber CR[6] is an example of a "fifth common liquid chamber". Branch portion FA[1] is an example of a "first branch portion," branch portion FA[3] is an example of a "second branch portion," branch portion FA[2] is an example of a "third branch portion," branch portion FA[5] is an example of a "fourth branch portion," and branch portion FA[6] is an example of a "fifth branch portion." Position LC[1] = LC[2] is an example of a "first position." Position LC[3] is an example of a "second position." Position LC[5] = LC[6] is an example of a "third position."

[0064] As an example, the control unit 10 executes, as the flushing process of the present embodiment, a first flushing operation and a second flushing operation that is started after the first flushing operation is completed.

[0065] In the first flushing operation of this embodiment, the nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6] are targeted for flushing, and ink I is ejected from the nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6] without ejecting ink from the nozzle groups Ns[3] and Ns[4].

[0066] Furthermore, in the second flushing operation of this embodiment, the nozzle groups Ns[1] to Ns[6] are targets for flushing, and the ink I is discharged from the nozzle groups Ns[1] to Ns[6]. During the first flushing operation, the amounts of ink I[1], I[2], I[5], and I[6] discharged from the nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6] are greater than the amounts of ink I[1] to I[6] discharged from the nozzle groups Ns[1] to Ns[6] during the second flushing operation. Also, the period during which the first flushing operation is performed is longer than the period during which the second flushing operation is performed.

[0067] During the first flushing operation, it is preferable that the total amount of ink discharged from the nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6] that are the targets of flushing be equal to or greater than half the volume of the common part CP or half the volume of the distribution flow path Q1. Furthermore, it is more preferable that the total amount of ink discharged from the nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6] during the first flushing operation is greater than or equal to the volume of the common part CP or the volume of the distribution flow path Q1.

[0068] During the first flushing operation, it is preferable that the total amount of ink discharged from nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6] is less than the amount of ink discharged when suction cleaning or pressure cleaning is performed on nozzle groups Ns[1] to Ns[6]. Furthermore, it is even more preferable that the total amount of ink discharged from the nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6] during the first flushing operation is less than the total amount of the flow paths downstream of the inlet 60A, i.e., the volume of the distribution flow path Q1, the volume of the common liquid chambers CR[1] to CR[6], the volume of the individual flow path groups IPs[1] to IPs[6], the volume of the multiple supply ports 774 communicating with each of the common liquid chambers CR[1] to CR[6], and the multiple outlets 60B.

[0069] Also, the first flushing operation is preferably an operation in which ink I is discharged from nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6] during the same period. Furthermore, the first flushing operation is preferably an operation in which ink I is discharged from all nozzles N constituting one nozzle group Ns. In this case, the discharge of ink I from all nozzles N constituting one nozzle group Ns may be performed simultaneously, or may be divided during the execution period of the first flushing operation without being performed simultaneously.

[0070] Furthermore, during the second flushing operation, the discharge amount of each of the inks I[1] to I[6] discharged from the nozzle groups Ns[1] to Ns[6] may be equal to or greater than the volume of one common liquid chamber CR.

[0071] Furthermore, during the second flushing operation, it is preferable that the discharge amount of each of the inks I[1] to I[6] discharged from the nozzle groups Ns[1] to Ns[6] is equal to or less than the volume of the flow path downstream of each of the branch positions Lc[1] to Lc[6]. Specifically, it is preferable that the discharge amount of the ink I[3] discharged from the nozzle group Ns[3] during the second flushing operation is equal to or less than the total volume of the branch portion FA, the common liquid chamber CR[3], and the individual flow path group IPs[3]. The same applies to the other nozzle groups Ns.

[0072] 1-3: Advantages of the First Embodiment As described above, the liquid ejection device 100 according to the present embodiment includes a plurality of common liquid chambers CR, a distribution flow path Q1, and an inlet 60A for introducing liquid into the distribution flow path Q1. The plurality of common liquid chambers CR include a common liquid chamber CR[1] communicating with the nozzle group Ns[1] and a common liquid chamber CR[3] communicating with the nozzle group Ns[3]. The distribution flow path Q1 has a common portion CP that is commonly connected to two or more common liquid chambers CR among the plurality of common liquid chambers CR, and a plurality of branch portions FA branching from the common portion CP. The plurality of branch portions FA include a branch portion FA[1] that branches from the common portion CP at a position LC[1] and communicates with the common liquid chamber CR[1], and a branch portion FA[3] that branches from the common portion CP at a position LC[3] and communicates with the common liquid chamber CR[3]. The length from the inlet 60A to the position LC[1] along the distribution flow path Q1 is longer than the length from the inlet 60A to the position LC[3] along the distribution flow path Q1. The control unit 10 executes a flushing process in which the amount of ink I[1] discharged from the nozzle group Ns[1] is greater than the amount of ink I[3] discharged from the nozzle group Ns[3].

[0073] According to this, there is no need to wastefully discharge normal ink in order to discharge all of the settled ink in the distribution flow path Q1 until the print result is no longer affected. As described above, since the length from the inlet 60A to the position LC[1] is longer than the length from the inlet 60A to the position LC[3], in the flushing process of the comparative example, the amount of settled ink discharged from the nozzle group Ns[1] is greater than the amount of settled ink discharged from the nozzle group Ns[3]. Therefore, in the flushing process of the present embodiment, the amount of ink discharged from the nozzle group Ns[1] is made greater than the amount of ink discharged from the nozzle group Ns[3], thereby reducing the amount of normal ink wasted from the nozzle group Ns[3] compared to the flushing process of the comparative example.

[0074] In the liquid ejection device 100, the control unit 10 performs a first flushing operation to discharge at least the ink I[1] from the nozzle group Ns[1] without discharging the ink I[3] from the nozzle group Ns[3] as a flushing process, and then performs a second flushing operation to discharge at least the ink I[3] from the nozzle group Ns[3]. The amount of the ink I[1] discharged from the nozzle group Ns[1] by the first flushing operation is greater than the amount of the ink I[3] discharged from the nozzle group Ns[3] by the second flushing operation.

[0075] According to this, the first flushing operation first discharges the settled ink that has accumulated in the common part CP, and then the second flushing operation eliminates the accumulation of settled ink in the common liquid chamber CR, thereby further reducing wasted ink.

[0076] Furthermore, in the second flushing operation in the liquid ejecting apparatus 100, the control unit 10 ejects the ink I[1] from the nozzle group Ns[1].

[0077] This reduces the amount of ink I to be discharged from the nozzle group Ns[1] by the first flushing operation, thereby shortening the execution period of the first flushing operation, and as a result, the time required for the flushing process can be shortened.

[0078] Furthermore, in the liquid ejecting device 100, the amount of ink I discharged in the first flushing operation is less than the volume of the flow path downstream of the inlet 60A.

[0079] This makes it possible to reduce the amount of ink I that is wasted in the first flushing operation.

[0080] Furthermore, in the liquid ejecting apparatus 100, the amount of ink I[3] discharged from the nozzle group Ns[3] by the second flushing operation is equal to or greater than the volume of the common liquid chamber CR[3].

[0081] This increases the likelihood that the accumulation of settled ink in the common liquid chamber CR[3] can be eliminated.

[0082] Furthermore, in the liquid ejecting device 100, the amounts of ink I discharged from the nozzle group Ns[1] and the nozzle group Ns[3] during the second flushing operation are approximately equal.

[0083] This simplifies the control of the second flushing operation. Also, the time for the second flushing operation for the nozzle group Ns[1] and the time for the second flushing operation for the nozzle group Ns[3] can be made substantially equal, thereby shortening the time for the second flushing operation.

[0084] Furthermore, in the liquid ejecting device 100, the amount of ink I discharged in the first flushing operation is equal to or greater than half the volume of the common portion CP.

[0085] This increases the likelihood that the accumulation of settled ink in the distribution channel Q1 can be eliminated, making it possible to reduce wasted ink I.

[0086] Furthermore, in the liquid ejecting apparatus 100, the first flushing operation is an operation in which the ink I[1] is discharged from all the nozzles N that constitute the nozzle group Ns[1].

[0087] According to this, by applying a strong negative pressure to the distribution channel Q1 via the branch portion FA[1] that communicates with the nozzle group Ns[1], the settled ink in the distribution channel Q1 can be quickly discharged.

[0088] In the liquid ejection device 100, the common liquid chambers CR each have a common liquid chamber CR[2] that communicates with the nozzle group Ns[2]. The branch portions FA each include a branch portion FA[2] that communicates with the common liquid chamber CR[2]. The branch portions FA[1] and FA[2] each branch separately at a position LC[1]=LC[2] that is located at one end of the common portion CP. The branch portion FA[3] each branch separately at a position LC[3] that is located between the position LC[1]=LC[2] and the inlet 60A.

[0089] According to this, there is no need to wastefully discharge normal ink in order to discharge all of the sedimented ink in the distribution flow path Q1 until the print result is no longer affected. As described above, in the flushing process of the comparative example, the flow rate of the ink in the common part CP is fast, so that the sedimented ink in the common part CP easily flows into the nozzle group Ns[1], and the flow rate of the ink in the branch part FA[3] is slow, so that the sedimented ink does not easily flow into the nozzle group Ns[3]. Therefore, in the flushing process of this embodiment, the amount of ink discharged from the nozzle group Ns[1] into which the sedimented ink in the common part CP easily flows is made larger than the amount of ink discharged from the nozzle group Ns[3] into which the sedimented ink in the common part CP does not easily flow, thereby reducing the wasteful discharge of normal ink from the nozzle group Ns[3] compared to the flushing process of the comparative example. In particular, when the number of branch parts FA is five or more as in this embodiment, the flow rate of the ink flowing in the common part CP is easily biased in the flushing process of the comparative example regardless of the position where the inlet 60A is arranged, so that the above effect is remarkable.

[0090] Furthermore, in the liquid ejecting apparatus 100, the amount of ink I[2] discharged from the nozzle group Ns[2] during the flushing process is greater than the amount of ink I[3] discharged from the nozzle group Ns[3] during the flushing process.

[0091] This can shorten the time required for the flushing process. As described above, in the flushing process of the comparative example, the ink flow rate in the common part CP is fast, just like in the nozzle group Ns[1], so the settled ink in the common part CP tends to flow into the nozzle group Ns[2]. Therefore, by making the ink discharge amount from each of the nozzle groups Ns[1] and Ns[2] in the flushing process greater than the ink discharge amount from the nozzle group Ns[3], normal ink is not discharged unnecessarily from the nozzle group Ns[2], and the settled ink in the common part CP can be discharged quickly.

[0092] Furthermore, in the liquid ejecting device 100, the discharge amount of the ink I[1] discharged from the nozzle group Ns[1] is approximately equal to the discharge amount of the ink I[2] discharged from the nozzle group Ns[2].

[0093] According to this, the ink flow speed from position LC[1] = LC[2] toward branch portion FA[1] can be made substantially equal to the ink flow speed from position LC[1] = LC[2] toward branch portion FA[2]. Therefore, in order to discharge the settled ink in the common portion CP, the period for performing flushing on nozzle group Ns[1] and the period for performing flushing on nozzle group Ns[2] can be made substantially equal, thereby shortening the flushing process time compared to when the two are different.

[0094] In the liquid ejecting device 100, the common liquid chambers CR further include a common liquid chamber CR[5] communicating with the nozzle group Ns[5] and a common liquid chamber CR[6] communicating with the nozzle group Ns[6]. The branch portions FA include a branch portion FA[5] communicating with the common liquid chamber CR[5] and a branch portion FA[6] communicating with the common liquid chamber CR[6]. The branch portions FA[5] and FA[6] are each separately branched at a position LC[5]=LC[6] disposed at the other end of the common portion CP. In the flushing process, the amount of ink I[5] discharged from the nozzle group Ns[5] is greater than the amount of ink I[3] discharged from the nozzle group Ns[3]. In the flushing process, the amount of ink I[6] discharged from the nozzle group Ns[6] is greater than the amount of ink I[3] discharged from the nozzle group Ns[3].

[0095] According to this, by efficiently discharging the settled ink from both ends of the common portion CP, the flushing process time can be shortened and the amount of wasted ink I can be reduced.

[0096] Furthermore, in the liquid ejection device 100, the number of branch portions FA branching off from the common portion CP between the position LC[1]=LC[2] and the inlet 60A is the same as the number of branch portions FA branching off from the common portion CP between the position LC[5]=LC[6] and the inlet 60A. In the flushing process, the amounts of ink I discharged from the nozzle group Ns[1], the nozzle group Ns[2], the nozzle group Ns[5], and the nozzle group Ns[6] are approximately equal.

[0097] According to this, when the first flushing operation is performed, even if flushing is performed on each of the nozzle group Ns[1], the nozzle group Ns[2], the nozzle group Ns[5], and the nozzle group Ns[6] during the same period, the ink I flows evenly in the common portion CP based on the inlet 60A. As a result, the liquid ejecting device 100 can reduce printing unevenness after the flushing process is completed.

[0098] The liquid ejecting device 100 according to the present embodiment includes a plurality of common liquid chambers CR, a distribution flow path Q1, and an inlet 60A for introducing ink I into the distribution flow path Q1. The plurality of common liquid chambers CR include a common liquid chamber CR[1] communicating with the nozzle group Ns[1] and a common liquid chamber CR[3] communicating with the nozzle group Ns[3]. The distribution flow path Q1 has a common portion CP that is commonly communicating with the plurality of common liquid chambers CR, and a plurality of branch portions FA branching from the common portion CP. The plurality of branch portions FA include a branch portion FA[1] communicating with the common liquid chamber CR[1] and a branch portion FA[3] communicating with the common liquid chamber CR[3]. The branch portion FA[1] branches off individually at one end of the common portion CP. The branch portion FA[3] branches off individually between the one end and the inlet 60A. The control unit 10 executes a flushing process in which a first flushing operation is performed to discharge at least the ink I[1] from the nozzle group Ns[1] without discharging the ink I[3] from the nozzle group Ns[3], and then a second flushing operation is performed to discharge at least the ink I[3] from the nozzle group Ns[3]. The amount of the ink I[1] discharged from the nozzle group Ns[1] by the first flushing operation is greater than the amount of the ink I[3] discharged from the nozzle group Ns[3] by the second flushing operation.

[0099] According to this, by first discharging the settled ink in the common portion CP and then discharging the settled ink remaining in the common liquid chamber CR, it is possible to reduce wasted ink I compared to the flushing process of the comparative example.

[0100] 2: Variations The above-mentioned embodiments can be modified in various ways. Specific modified embodiments are illustrated below. Two or more embodiments selected from the following examples can be combined as long as they are not mutually contradictory.

[0101] 2-1: First modified version In the first embodiment, ink I was discharged from nozzle groups Ns[1], Ns[2], Ns[3], Ns[4], Ns[5], and Ns[6] during the second flushing operation. However, this variant differs from the first embodiment in that ink I is not discharged from nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6] for which the first flushing operation is to be performed during the second flushing operation.

[0102] When ink I is not discharged from the nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6] for which the first flushing operation is to be performed, the total amount of ink discharged from the nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6] during the first flushing operation is preferably greater than or equal to the sum of the volume of one common liquid chamber CR and the volume of the distribution flow path Q1, and more preferably greater than or equal to the sum of the volumes of the common liquid chambers CR[1], CR[2], CR[5], and CR[6] corresponding to the nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6] for which the first flushing operation is to be performed, and the volume of the distribution flow path Q1. This increases the likelihood that all of the settled ink can be discharged from the flow path downstream of the inlet 60A, except for the common liquid chambers CR[3], CR[4] and the branch portions FA[3], FA[4] that communicate with the nozzle groups Ns[3], Ns[4] for which the first flushing operation is not performed. Therefore, by not performing the second flushing operation on the nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6], it is possible to prevent the ink that has not settled from being discharged unnecessarily.

[0103] As described above, the control unit 10 does not discharge the ink I[1] from the nozzle group Ns[1] in the second flushing operation in the liquid ejecting device 100. This makes it possible to reduce wasted ink I because the second flushing operation is not performed on the nozzle group Ns[1] from which the settled ink has already been discharged.

[0104] Furthermore, in the liquid ejecting device 100, the amount of ink I[1] discharged by the first flushing operation is equal to or greater than the combined volume of the distribution flow path Q1 and the common liquid chamber CR[1]. This increases the likelihood that the retention of settled ink in the distribution flow path Q1 can be eliminated.

[0105] 2-2: Second variant In the first embodiment, the flushing process is performed in which the discharge amount of ink I discharged from each of the nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6] is greater than the discharge amount of ink I discharged from each of the nozzle groups Ns[3] and Ns[4]. In this modified example, the flushing process is performed in which the discharge amount of ink I discharged from one of the nozzle groups Ns[1] and Ns[2] and one of the nozzle groups Ns[5] and Ns[6] is greater than the discharge amount of ink I discharged from the other of the nozzle groups Ns[1] and Ns[2], the other of the nozzle groups Ns[5] and Ns[6], and the nozzle groups Ns[3] and Ns[4]. This modified example differs from the first embodiment in that the flushing process requires a longer period of time than the first embodiment, but the same effects as the first embodiment can be achieved.

[0106] 2-3: Third variant In the first embodiment, the total amount of ink discharged in the first flushing operation was determined in advance, but this modified example differs from the first embodiment in that pressure fluctuations in a pressure chamber C communicating with the nozzles N that constitute the nozzle group Ns for which the first flushing operation is to be performed are detected, and the first flushing operation for the nozzle group Ns is terminated based on the detection results.

[0107] Specifically, when the control unit 10 supplies a drive signal to the piezoelectric element 732 to drive the piezoelectric element 732 to generate a pressure fluctuation in the ink in the pressure chamber C, residual vibration is generated in the ink in the pressure chamber C after driving the piezoelectric element 732. This residual vibration of the ink in the pressure chamber C causes the diaphragm 73 to vibrate together with the piezoelectric element 732, generating a piezoelectric effect in the piezoelectric element 732, and a residual vibration voltage change is induced in the electrodes that constitute the piezoelectric element 732. This residual vibration voltage change is detected by the control unit 10 as a damped vibration waveform.

[0108] After performing the first flushing operation for a certain period of time, the control unit 10 detects a residual vibration voltage change that is correlated with the pressure fluctuation in the pressure chamber C, and estimates the viscosity of the ink I based on the detection result. For example, it is estimated that the lower the viscosity of the ink I, the larger the amplitude of the damped vibration of the damped vibration waveform. If the estimated viscosity is below a predetermined value, the amount of settled ink remaining in the branch portion FA, the common liquid chamber CR, and the individual flow path group IPs that are the targets of the first flushing operation is expected to have decreased to an allowable range, and the control unit 10 ends the first flushing operation. On the other hand, if the estimated viscosity is above the predetermined value, the control unit 10 resumes the first flushing operation, and after a certain period of time has passed, it determines whether to end the first flushing operation by estimating the viscosity again. This is repeated thereafter. The length of the certain period of time for performing the first flushing operation may be set arbitrarily, but it is preferable that the period of the second and subsequent first flushing operations is shorter than the period of the first first flushing operation.

[0109] When the control unit 10 ends the first flushing operation for the nozzle group Ns based on the detection result of the pressure fluctuation, in the second flushing operation, it is preferable not to discharge the ink I from the nozzle group Ns that is the target of the first flushing operation. In other words, in the second flushing operation, it is preferable to discharge the ink I only from the nozzle groups Ns[3] and Ns[4].

[0110] In addition, when there are multiple nozzle groups Ns to which the first flushing operation is to be performed, the control unit 10 may detect pressure fluctuations in the pressure chambers C communicating with the nozzles N constituting any one of the nozzle groups Ns, and terminate the first flushing operation for each of the multiple nozzle groups Ns based on the detection results. By shortening the time for viscosity detection, the time for the flushing process can be shortened. In this modification, among the branch portions FA[1], FA[2], FA[5], and FA[6] communicating with the nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6] to which the first flushing operation is to be performed, the length of each of the flow paths of the branch portions FA[1] and FA[6] is slightly longer than the length of each of the flow paths of the branch portions FA[2] and FA[5]. Therefore, it is preferable to detect pressure fluctuations in a pressure chamber C connected to a nozzle N that constitutes either the nozzle group Ns[1] or Ns[6], and terminate the first flushing operation for the nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6] based on the detection results.

[0111] Also, similarly to the first flushing operation, pressure fluctuations within the pressure chambers C communicating with the nozzles N constituting the nozzle group Ns for which the second flushing operation is to be performed may be detected, and the second flushing operation for the nozzle group Ns for which the second flushing operation is to be performed may be terminated based on the detection results. Also, when there are multiple nozzle groups Ns for which the second flushing operation is to be performed, it is preferable to detect pressure fluctuations within the pressure chambers C communicating with the nozzles N constituting the nozzle group Ns farthest from the inlet 60A, and terminate the second flushing operation for the nozzle group Ns for which the second flushing operation is to be performed based on the detection results.

[0112] As described above, in the liquid ejection device 100, the pressure fluctuation in the pressure chamber C communicating with the nozzles N constituting the nozzle group Ns[1] is detected, and the first flushing operation for the nozzle group Ns[1] is terminated based on the detection result. This allows the first flushing operation to be performed just enough depending on the state of the settled ink. Also, there are cases where the discharge amount of the ink I in the first flushing operation can be set to be equal to or less than the volume of the distribution flow path Q1.

[0113] Furthermore, the ink I[1] is not discharged from the nozzle group Ns[1] during the second flushing operation of the liquid ejecting device 100. This makes it possible to reduce the amount of ink I discharged that is not wasted, since it has already been confirmed that the settled ink is not remaining in the nozzle group Ns[1].

[0114] 2-4: Fourth variant In the above embodiment, the inlet 60A is disposed between the position LC[3] and the position LC[4] in the X-axis direction. However, the inlet 60A may be disposed in another position.

[0115] Fig. 11 is an explanatory diagram of a flow path formed inside a liquid distributor 60 according to a fourth modified example. In the example shown in Fig. 11, an inlet 60A is located in the common part CP between position LC[4] and position LC[5] corresponding to the end opposite to position LC[2]. The number of branch portions FA branching from the common portion CP between position LC[2] and the inlet 60A is greater than the number of branch portions FA branching from the common portion CP between position LC[5] and the inlet 60A. Specifically, the number of branch portions FA branching from the common portion CP between position LC[2] and the inlet 60A is two, namely, branch portions FA[3] and FA[4], and the number of branch portions FA branching from the common portion CP between position LC[5] and the inlet 60A is zero.

[0116] In the example shown in FIG. 11, the amount of settled ink in the common portion CP between position LC[2] and the inlet 60A is expected to be greater than the amount of settled ink between position LC[5] and the inlet 60A.

[0117] Therefore, the control unit 10 executes a first flushing operation in which the amount of ink I discharged from the nozzle groups Ns[1] and Ns[2] is greater than the amount of ink I discharged from the nozzle groups Ns[5] and Ns[6]. After that, the control unit 10 executes a second flushing operation in which the amount of ink I discharged from the nozzle groups Ns[3] and Ns[4] is less than the amount of ink I discharged from the nozzle groups Ns[5] and Ns[6].

[0118] The control unit 10 executes a first operation of discharging the ink I from the nozzle groups Ns[1] and Ns[2] as the first flushing operation. After the first operation is completed, the control unit 10 then executes a second operation of discharging the ink I from the nozzle groups Ns[5] and Ns[6] as the first flushing operation. Finally, the control unit 10 executes an operation of discharging the ink I from the nozzle groups Ns[3] and Ns[4] as the second flushing operation. In this way, by dividing the first flushing operation into the first operation for the nozzle groups Ns[1] and Ns[2] and the second operation of discharging the ink from the nozzle groups Ns[5] and Ns[6], it is possible to suppress a shortage of ink supply from the inlet 60A to the nozzle groups Ns compared to the case where the first operation and the second operation are performed simultaneously. In addition, the second flushing operation may also be divided and executed for each nozzle group Ns.

[0119] In the fourth modified example, the number of branched portions FA branching from the common portion CP between the position LC[2] and the inlet 60A is greater than the number of branched portions FA branching from the common portion CP between the position LC[5] and the inlet 60A, and in the flushing process, the discharge amount of ink discharged from the nozzle groups Ns[1] and Ns[2] is greater than the discharge amount of ink discharged from the nozzle groups Ns[5] and Ns[6]. According to this, the discharge amount of ink discharged from the nozzle groups Ns[1] and Ns[2], which need to discharge more settled ink in the common portion CP than the nozzle groups Ns[5] and Ns[6], is made greater than the discharge amount of ink discharged from the nozzle groups Ns[5] and Ns[6], thereby reducing the discharge of unnecessary ink I from the nozzle groups Ns[5] and Ns[6]. In other words, the discharge amount of ink I can be optimized according to the position of the inlet 60A.

[0120] Note that the control unit 10 may execute an operation of discharging ink I from the nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6] during the same period as the first flushing operation. As described above, in this modification, in the flushing process, the discharge amount of ink I discharged from the nozzle groups Ns[1] and Ns[2] is greater than the discharge amount of ink I discharged from the nozzle groups Ns[5] and Ns[6]. Therefore, for example, during the first flushing operation, the frequency of ejecting ink I by flushing from the nozzle groups Ns[5] and Ns[6] is set to be less than the frequency of ejecting ink I by flushing from the nozzle groups Ns[1] and Ns[2], in other words, the number of times ink I is ejected by flushing from each of the nozzle groups Ns[5] and Ns[6] is set to be less than the number of times ink I is ejected by flushing from each of the nozzle groups Ns[1] and Ns[2], so that an operation of ejecting ink I from the nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6] can be performed as the first flushing operation during the same period. As another example, the weight of the ink droplets ejected from the nozzles N by flushing may be changed, so that an operation of ejecting ink I from the nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6] can be performed as the first flushing operation during the same period.

[0121] Furthermore, in the second flushing operation, ink I may be discharged not only from the nozzle groups Ns[3] and Ns[4], but also from the nozzle groups Ns[1], Ns[2], Ns[5] and Ns[6].

[0122] 2-5: Fifth variant In the above embodiment, the trunk EA is connected to six branch portions FA[1] to FA[6]. However, the number of branch portions FA to which the trunk EA is connected may be any number equal to or greater than two.

[0123] 12 to 14 are explanatory diagrams of flow paths formed inside a liquid distributor 60 according to a fifth modified example. In the example shown in Fig. 12 to 14, the trunk portion EA communicates with five branch portions FA[1] to FA[5].

[0124] 12, the inlet 60A is at the same position as the position LC[3] in the X-axis direction. That is, the length from the inlet 60A to the position LC[3] can be regarded as 0, and is shorter than the length from the inlet 60A to the position LC[1]=LC[2] and the length from the inlet 60A to the position LC[4]=LC[5]. Therefore, the control unit 10 executes a flushing process in which the amount of ink I discharged from each of the nozzle groups Ns[1], Ns[2], Ns[4], and Ns[5] is greater than the amount of ink I[3] discharged from the nozzle group Ns[3].

[0125] The liquid ejection device 100 according to the modified example of FIG. 12 includes a plurality of common liquid chambers CR, a distribution flow path Q1, and an inlet 60A for introducing liquid into the distribution flow path Q1. The plurality of common liquid chambers CR include a common liquid chamber CR[1] communicating with the nozzle group Ns[1] and a common liquid chamber CR[3] communicating with the nozzle group Ns[3]. The distribution flow path Q1 has a common portion CP that is commonly communicating with two or more common liquid chambers CR among the plurality of common liquid chambers CR, and a plurality of branch portions FA branching from the common portion CP. The plurality of branch portions FA include a branch portion FA[1] that branches from the common portion CP at a position LC[1] and communicates with the common liquid chamber CR[1], and a branch portion FA[3] that branches from the common portion CP at a position LC[3] and communicates with the common liquid chamber CR[3]. The length from the inlet 60A to the position LC[1] along the distribution flow path Q1 is longer than the length from the inlet 60A to the position LC[3] along the distribution flow path Q1. The control unit 10 executes a flushing process in which the amount of ink I[1] discharged from the nozzle group Ns[1] is greater than the amount of ink I[3] discharged from the nozzle group Ns[3]. This can provide the same effects as the first embodiment.

[0126] Note that the modified example in Figure 12 differs from the first embodiment in that the nozzle group Ns[4] is an example of the "fourth nozzle group," the nozzle group Ns[5] is an example of the "fifth nozzle group," the common liquid chamber CR[4] is an example of the "fourth common liquid chamber," the common liquid chamber CR[5] is an example of the "fifth common liquid chamber," the branch portion FA[4] is an example of the "fourth branch portion," the branch portion FA[5] is an example of the "fifth branch portion," and the position LC[4] = LC[5] is an example of the "third position."

[0127] In FIG. 13, the inlet 60A is located at position LC[5]. In FIG. 14, the inlet 60A is located in the -X direction from position LC[5]. In other words, the inlet 60A is located at a position corresponding to the other end of the common part CP opposite to position LC[1]=LC[2], which is one end of the common part CP. Here, the "position corresponding to the other end of the common part CP" corresponds to the position where the inlet 60A of the area is located when the inlet 60A is located at any position within the area from position LC[5] to the end of the trunk part EA in the -X direction. Therefore, it is preferable that the control unit 10 executes a flushing process in which the discharge amount of the ink I discharged from the nozzle groups Ns[1] and Ns[2] is greater than the discharge amount of the ink I discharged from the nozzle groups Ns[3], Ns[4], and Ns[5].

[0128] 13 and 14, the inlet 60A is disposed at a position corresponding to the other end of the common part CP. This makes it possible to reduce wasted ink I by increasing only the amount of ink I discharged from the nozzle group Ns[1] communicating with the branch part FA[1] that branches at position LC[1]=LC[2] and the nozzle group Ns[2] communicating with the branch part FA[2].

[0129] 13 and 14, the amount of ink I discharged from the nozzle group Ns[1] communicating with the branch portion FA[1] branching at the position LC[1]=LC[2] at one end of the common portion CP may be greater than the amount of ink I discharged from the other nozzle groups Ns[2]-Ns[5]. Also, the amount of ink I discharged from the nozzle group Ns[2] communicating with the branch portion FA[2] branching at the position LC[1]=LC[2] at one end of the common portion CP may be greater than the amount of ink I discharged from the other nozzle groups Ns[1], Ns[3]-Ns[5].

[0130] 2-6: 6th variant FIG. 15 is an explanatory diagram of a flow path formed inside the liquid distributor 60 according to the sixth modified example. In the example shown in FIG. 15, the backbone EA communicates with two branch portions FA[1]-FA[2]. The two branch portions FA[1]-FA[2] branch from the common portion CP at the same position LC[1]=LC[2]. The distance from the inlet 60A to the common liquid chamber CR[1] is longer than the distance from the inlet 60A to the common liquid chamber CR[2]. In this modified example, the "distance from the inlet 60A to the common liquid chamber CR[1]" corresponds to the total flow path length of the common portion CP, the branch portion FA[1], the outlet 60B connected to the branch portion FA[1], and the supply port 774, and the "distance from the inlet 60A to the common liquid chamber CR[2]" corresponds to the total flow path length of the common portion CP, the branch portion FA[2], the outlet 60B connected to the branch portion FA[2], and the supply port 774. Therefore, it is preferable that the control unit 10 executes a flushing process in which the amount of ink I[1] discharged from the nozzle group Ns[1] is greater than the amount of ink I[2] discharged from the nozzle group Ns[2].

[0131] The liquid ejection device 100 of this modification includes a common liquid chamber CR[1], which is an example of a "first common liquid chamber" communicating with a nozzle group Ns[1], which is an example of a "first nozzle group", a common liquid chamber CR[2], which is an example of a "second common liquid chamber" communicating with a nozzle group Ns[2], which is an example of a "second nozzle group", a distribution flow path Q1 for distributing and supplying ink to the common liquid chamber CR[1] and the common liquid chamber CR[2], and an inlet 60A for introducing ink into the distribution flow path Q1. In addition, the length of the flow path from the inlet 60A to the common liquid chamber CR[1] is longer than the length of the flow path from the inlet 60A to the common liquid chamber CR[2]. Then, the control unit 10 executes a flushing process in which the amount of ink I discharged from the nozzle group Ns[1] is greater than the amount of ink I discharged from the nozzle group Ns[2]. This can achieve the same effect as the first embodiment.

[0132] 2-7: 7th variant In the above embodiment, the branch portion FA[1] branches off from the trunk EA at position LC[1]. Also, the branch portion FA[2] branches off from the trunk EA at position LC[2]. That is, the two branch portions FA[1] and FA[2] branch off individually from the trunk EA at position LC[2], which is the end of the common portion CP. However, any number of branch portions FA may branch off individually from the trunk EA at the end of the common portion CP. Fig. 16 is an explanatory diagram of the flow paths formed inside the liquid distributor 60 according to the seventh modified example. In the example shown in Fig. 16, three branch portions FA[1], FA[2], and FA[6] individually branch off from the trunk portion EA at the same position LC[1] = LC[2] = LC[6], which is the end of the common portion CP.

[0133] The control unit 10 executes a flushing process in which the amount of ink I[1] discharged from the nozzle group Ns[1], the amount of ink I[2] discharged from the nozzle group Ns[2], and the amount of ink I[6] discharged from the nozzle group Ns[6] are all equal.

[0134] Note that the seventh modified example differs from the first embodiment in that the nozzle group Ns[6] is an example of the "sixth nozzle group," the common liquid chamber CR[6] is an example of the "sixth common liquid chamber," the branch portion FA[6] is an example of the "sixth branch portion," and the position LC[1] = LC[2] = LC[6] is an example of the "first position."

[0135] In the liquid ejection device 100 of the seventh modification, the common liquid chambers CR include a common liquid chamber CR[6] that communicates with the nozzle group Ns[6], and the branch portions FA include a branch portion FA[6] that communicates with the common liquid chamber CR[6], and the branch portion FA[6] branches off separately from the branch portions FA[1] and FA[2] at a position LC[1]. The control unit 10 executes a flushing process in which the amounts of ink discharged from the nozzle groups Ns[1], Ns[2], and Ns[6] are approximately equal. This allows the flushing process time to be shortened.

[0136] 2-8: 8th variant Although the flushing process of the first embodiment includes a first flushing operation and a second flushing operation performed after the first flushing operation, the flushing process may include only one flushing operation performed in the same period. For example, if the amount of ink I discharged from each nozzle group Ns in the flushing process is the same as in the first embodiment, the flushing process of this modification may perform flushing for the nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6] that discharge a relatively large amount of ink I, and flushing for the nozzle groups Ns[3] and Ns[4] that discharge a relatively small amount of ink I, in the same period. In this case, during the flushing process, the frequency of ejecting ink I by flushing from the nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6] is set to be higher than the frequency of ejecting ink I by flushing from the nozzle groups Ns[3] and Ns[4], in other words, the number of times that ink is ejected by flushing from each of the nozzle groups Ns[3] and Ns[4] is set to be lower than the number of times that ink is ejected by flushing from each of the nozzle groups Ns[1], Ns[2], Ns[5], and Ns[6]. Note that by varying the weight of the ink droplets ejected from the nozzles N by flushing, an operation of ejecting ink I from the nozzle groups Ns[1] to Ns[6] as a flushing process may be performed during the same period. [Explanation of symbols]

[0137] 10...control unit, 12...transport mechanism, 14...liquid ejection head, 16...pump, 18...liquid container, 52...filter unit, 54...connecting member, 56...wiring board, 58...fixing plate, 60...liquid distribution unit, 60A...inlet, 60B...outlet, 60C...opening, 62...first flow path board, 64...second flow path board, 70...ejection head unit, 71...flow path forming board, 72...pressure chamber forming board, 73...vibration plate, 74...nozzle plate, 75...compliance unit, 76...protection plate, 77...support, 78...wiring board, 100...liquid ejection device, 142...housing, 526...filter, 528...outlet, 542...through hole, 562...cutting notch, 642...groove portion, 712...opening, 714...first communicating flow path, 716...supply flow path, 718...second communicating flow path, 722...opening, 732...piezoelectric element, 752...sealing plate, 754...support, 772...space, 774...supply port, C...pressure chamber, CP...common portion, CR...common liquid chamber, DI2...outlet, EA...main portion, FA...branching portion, G1...flow path structure, G2...flow path control unit, G3...liquid ejection unit, I...ink, IP...individual flow path, IPs...individual flow path group, M...medium, N...nozzle, Ns...nozzle group, Q...distribution flow path, Q1...distribution flow path, SI3...supply port, U2...flow path control unit, U3...liquid ejection unit

Claims

1. a plurality of common liquid chambers including a first common liquid chamber communicating with the first nozzle group and a second common liquid chamber communicating with the second nozzle group; a distribution flow path including a common portion commonly communicating with two or more of the plurality of common liquid chambers, and a plurality of branch portions branching off from the common portion; an inlet for introducing liquid into the distribution channel; Equipped with The plurality of branched portions are a first branched portion branching from the common portion at a first position and communicating with the first common liquid chamber; a second branched portion branching from the common portion at a second position and communicating with the second common liquid chamber; a length from the inlet to the first position along the distribution flow path is longer than a length from the inlet to the second position along the distribution flow path, A flushing process is executed in which the amount of liquid discharged from the first nozzle group is greater than the amount of liquid discharged from the second nozzle group. A liquid ejection apparatus comprising:

2. in the flushing process, a first flushing operation is performed in which liquid is discharged from at least the first nozzle group without discharging liquid from the second nozzle group, and then a second flushing operation is performed in which liquid is discharged from at least the second nozzle group; a discharge amount of liquid discharged from the first nozzle group by the first flushing operation is greater than a discharge amount of liquid discharged from the second nozzle group by the second flushing operation; The liquid ejecting apparatus according to claim 1 .

3. In the second flushing operation, liquid is discharged from the first nozzle group. The liquid ejecting apparatus according to claim 2 .

4. A discharge amount of the liquid discharged by the first flushing operation is less than a volume of the flow path downstream of the inlet. The liquid ejecting apparatus according to claim 3 .

5. a discharge amount of the liquid discharged from the second nozzle group by the second flushing operation is equal to or greater than a volume of the second common liquid chamber. The liquid ejecting apparatus according to claim 3 .

6. the amount of liquid discharged from the first nozzle group and the amount of liquid discharged from the second nozzle group by the second flushing operation are substantially equal; The liquid ejecting apparatus according to claim 3 .

7. In the second flushing operation, liquid is not discharged from the first nozzle group. The liquid ejecting apparatus according to claim 2 .

8. a discharge amount of the liquid discharged by the first flushing operation is equal to or greater than a total volume of the distribution flow path and the first common liquid chamber; The liquid ejecting apparatus according to claim 7 .

9. ending the first flushing operation for the first nozzle group based on a detection result of a pressure fluctuation in a pressure chamber communicating with the nozzles that constitute the first nozzle group; The liquid ejecting apparatus according to claim 2 .

10. In the second flushing operation, liquid is not discharged from the first nozzle group. The liquid ejection apparatus according to claim 9 .

11. The amount of liquid discharged by the first flushing operation is equal to or greater than half the volume of the common portion. The liquid ejecting apparatus according to claim 2 .

12. the first flushing operation is an operation of discharging liquid from all nozzles constituting the first nozzle group; The liquid ejecting apparatus according to claim 2 .

13. the plurality of common liquid chambers include a third common liquid chamber communicating with a third nozzle group, the plurality of branch portions include a third branch portion communicating with the third common liquid chamber, each of the first and third branched portions branching separately at the first location disposed at one end of the common portion; The second branched portion branches off individually at the second position disposed between the first position and the inlet. The liquid ejecting apparatus according to claim 1 .

14. In the flushing process, an amount of liquid discharged from the third nozzle group is greater than an amount of liquid discharged from the second nozzle group. The liquid ejection apparatus according to claim 13 .

15. In the flushing process, a discharge amount of liquid discharged from the first nozzle group and a discharge amount of liquid discharged from the third nozzle group are substantially equal to each other. The liquid ejection apparatus according to claim 14 .

16. The inlet is disposed at a position corresponding to the other end of the common portion. The liquid ejection apparatus according to claim 14 .

17. the plurality of common liquid chambers further include a fourth common liquid chamber communicating with a fourth nozzle group and a fifth common liquid chamber communicating with a fifth nozzle group, the plurality of branch portions include a fourth branch portion communicating with the fourth common liquid chamber and a fifth branch portion communicating with the fifth common liquid chamber, each of the fourth and fifth branch portions branching separately at a third location disposed at the other end of the common portion; In the flushing process, an amount of liquid discharged from the fourth nozzle group is greater than an amount of liquid discharged from the second nozzle group, In the flushing process, an amount of liquid discharged from the fifth nozzle group is greater than an amount of liquid discharged from the second nozzle group. The liquid ejection apparatus according to claim 14 .

18. the number of the branched portions branching from the common portion between the first position and the inlet is equal to the number of the branched portions branching from the common portion between the third position and the inlet, In the flushing process, the discharge amounts of liquid discharged from the first nozzle group, the third nozzle group, the fourth nozzle group, and the fifth nozzle group are approximately equal. The liquid ejection apparatus according to claim 17 .

19. the number of the branched portions branching from the common portion between the first position and the inlet is greater than the number of the branched portions branching from the common portion between the third position and the inlet, In the flushing process, each of the discharge amounts of liquid discharged from the first nozzle group and the discharge amount of liquid discharged from the third nozzle group is greater than each of the discharge amounts of liquid discharged from the fourth nozzle group and the discharge amount of liquid discharged from the fifth nozzle group. The liquid ejection apparatus according to claim 17 .

20. the plurality of common liquid chambers include a sixth common liquid chamber communicating with a sixth nozzle group, the plurality of branch portions include a sixth branch portion communicating with the sixth common liquid chamber, the sixth branch portion branches separately from the first and third branch portions at the first position; In the flushing process, the discharge amounts of liquid discharged from the first nozzle group, the third nozzle group, and the sixth nozzle group are approximately equal. The liquid ejection apparatus according to claim 13 .

21. a plurality of common liquid chambers including a first common liquid chamber communicating with the first nozzle group and a second common liquid chamber communicating with the second nozzle group; a distribution flow path including a common portion commonly communicating with the plurality of common liquid chambers and a plurality of branch portions branching from the common portion; an inlet for introducing liquid into the distribution channel; Equipped with the plurality of branch portions include a first branch portion communicating with the first common liquid chamber and a second branch portion communicating with the second common liquid chamber; the first branched portion branches off individually at one end of the common portion, The second branched portion branches separately between the one end and the inlet, performing a flushing process in which a first flushing operation is performed to discharge liquid from at least the first nozzle group without discharging liquid from the second nozzle group, and then a second flushing operation is performed to discharge liquid from at least the second nozzle group; a discharge amount of liquid discharged from the first nozzle group by the first flushing operation is greater than a discharge amount of liquid discharged from the second nozzle group by the second flushing operation; A liquid ejection apparatus comprising:

22. a first common liquid chamber communicating with the first nozzle group; a second common liquid chamber communicating with the second nozzle group; a distribution flow path for distributing and supplying liquid to the first common liquid chamber and the second common liquid chamber; an inlet for introducing liquid into the distribution channel; Equipped with a length of a flow path from the inlet to the first common liquid chamber is longer than a length of a flow path from the inlet to the second common liquid chamber, performing a flushing process in which the amount of liquid discharged from the first nozzle group is greater than the amount of liquid discharged from the second nozzle group; A liquid ejection apparatus comprising:

Images