HEAD SYSTEM, LIQUID SUPPLY SYSTEM, PRINTING APPARATUS, AND LIQUID DISTRIBUTING METHOD

Abstract

To provide a head system which can suppress deterioration of image quality due to temperature change of a liquid.SOLUTION: A head system comprises: a head; a first supply passage which has a first supply port into which a liquid is supplied, and extends between the first supply port and the head; and a first discharge passage which has a first discharge port for discharging the liquid, and extends between the first discharge port and the head. The head has a manifold extending along a prescribed direction, and two groups including a plurality of pressure chambers of which each is connected to a nozzle and the manifold. Two groups are arranged along a direction crossing the prescribed direction in the order of a first group, and a second group. One end of the manifold included in each of two groups is positioned on one side in the prescribed direction, and other end thereof is positioned on the other side in the prescribed direction. The first supply passage is connected to one end of the manifold included in the first group, and to the other end of the manifold included in the second group. The first discharge passage is connected to the other end of the manifold included in the first group, and to one end of the manifold included in the second group.SELECTED DRAWING: Figure 14

Description

[Technical field]

[0001] The present invention relates to a head system, a liquid supply system, a printing apparatus, and a liquid distribution method. [Background technology]

[0002] There are image recording devices that record images by ejecting liquid such as ink onto a medium such as paper via a liquid ejection head. A liquid ejection head generally includes a number of pressure chambers that contain liquid, a number of nozzles that are respectively connected to the number of pressure chambers, a flow path that distributes the liquid to the number of pressure chambers, and an actuator that applies pressure to the pressure chambers (for example, Patent Document 1). The liquid ejection head ejects liquid by increasing the internal pressure of a desired pressure chamber using an actuator, and pushing out ink from a nozzle connected to the pressure chamber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-36218 A Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors of the present invention have conducted extensive research into the quality of images formed by existing liquid ejection heads and have found that deterioration of image quality can occur due to changes in the temperature of the liquid.

[0005] An object of the present invention is to provide a head system, a liquid supply system, a printing apparatus, and a liquid distribution method that are capable of suppressing deterioration in image quality caused by temperature changes in the liquid. [Means for solving the problem]

[0006] According to a first aspect of the present invention, Head and a first supply flow path having a first supply port through which a liquid is supplied and extending between the first supply port and the head; A head system having a first outlet for discharging liquid and a first discharge flow path extending between the first outlet and the head, the head includes a manifold extending in a predetermined direction, and two groups including a plurality of pressure chambers, each of the pressure chambers being connected to a nozzle and the manifold; The two groups are arranged in the order of a first group and a second group along a cross direction that crosses the predetermined direction, one end of the manifold included in each of the two groups is located in one direction of the predetermined direction, and the other end of the manifold included in each of the two groups is located in the other direction of the predetermined direction; the first supply flow path is connected to the one end of the manifold included in the first group and the other end of the manifold included in the second group; A head system is provided in which the first discharge flow path is connected to the other end of the manifold included in the first group and the one end of the manifold included in the second group.

[0007] According to a second aspect of the present invention, A head system according to a first aspect; A first supply tank connected to the first supply flow path; A first discharge tank connected to the first discharge flow path; A liquid supply system is provided that includes a first differential pressure mechanism for generating a pressure differential between the first supply tank and the first discharge tank.

[0008] According to a third aspect of the present invention, A head system according to the first aspect; A first supply tank connected to the first supply flow path; A first discharge tank connected to the first discharge flow path; a first differential pressure mechanism that generates a differential pressure between the first supply tank and the first discharge tank; A second supply tank connected to the second supply flow path; A second discharge tank connected to the second discharge flow path; A liquid supply system is provided that includes a second differential pressure mechanism that generates a pressure differential between the second supply tank and the second discharge tank.

[0009] According to a fourth aspect of the present invention, A liquid supply system according to the second or third aspect; A printing device is provided that includes a medium transport section that transports a medium.

[0010] According to a fifth aspect of the present invention, A liquid flowing method for flowing liquid in a head, comprising the steps of: the head includes a manifold extending in a predetermined direction, and two groups including a plurality of pressure chambers, each of the pressure chambers being connected to a nozzle and the manifold; The two groups are arranged in the order of a first group and a second group along a cross direction that crosses the predetermined direction, flowing a liquid from one side to the other side in the predetermined direction in the manifolds included in the first group; A method is provided that includes flowing liquid from the other side to the one side in the predetermined direction in the manifolds included in the second group. Effect of the Invention

[0011] According to the head system, liquid supply system, printing apparatus, and liquid distribution method of the present invention, It is possible to suppress deterioration in image quality caused by changes in the temperature of the liquid. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a printer. [Diagram 2] FIG. 2 is a plan view showing a schematic configuration of the head unit. [Diagram 3] FIG. 3 is a perspective view of the head system according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a side view showing the positional relationship between the ink supply tube, the ink discharge tube, the first and second flow path blocks, the frame member, and the head. [Diagram 5] Fig. 5(a) is an exploded perspective view of the first and second flow path blocks, and Fig. 5(b) is a side view of the flow path forming portion of the first and second flow path blocks. [Figure 6] FIG. 6 is an exploded perspective view of the frame member and the head. [Figure 7] FIG. 7 is a plan view of the flow path unit and the actuator. [Figure 8] FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. [Figure 9] FIG. 9 is an explanatory diagram showing flow paths formed by the ink supply system according to the first embodiment of the present invention. [Figure 10] Fig. 10(a) is an exploded perspective view of the first and second flow path blocks of the modified example 1-1, and Fig. 10(b) is a side view of the flow path forming portion of the first and second flow path blocks of the modified example 1-1. [Figure 11] FIG. 11 is an explanatory diagram showing flow paths formed by the ink supply system of the modified example 1-1. [Figure 12] FIG. 12 is a perspective view of a head system according to the second embodiment of the present invention. [Figure 13] FIG. 13 is an exploded perspective view of the flow path member. [Figure 14] FIG. 14 is an explanatory diagram showing flow paths formed by an ink supply system according to the second embodiment of the present invention. [Figure 15] FIG. 15 is an explanatory diagram showing flow paths formed by the ink supply system of the modified example 2-1. [Figure 16] FIG. 16 is an exploded perspective view of a flow path member of Modification 2-2. [Figure 17] FIG. 17 is an explanatory diagram showing flow paths formed by the ink supply system of the modified example 2-2. [Figure 18] FIG. 18 is a plan view showing a modified embodiment of the manifold. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] [First embodiment] A head system HS1 (FIG. 2), an ink supply system ISS1, a printing apparatus 1000, and an ink distribution method according to a first embodiment of the present invention will be described with reference to FIGS.

[0014] <Printer 1000> 1, the printer 1000 mainly comprises four head units 100, a platen 700, a pair of transport rollers 801, 802, an ink tank IT, a control device CONT, and a housing 900 that houses these components. Inside the housing 900, a sub-tank (fill tank, supply tank) ST (FIG. 2) and a drain tank (recovery tank) DT (FIG. 2) are further provided, one for each of the four head units 100.

[0015] In the following description, the direction in which the pair of transport rollers 801, 802 are aligned, i.e., the direction in which the medium PM is transported during image formation, is referred to as the "medium feed direction" of the printer 1000. Regarding the "medium feed direction," the upstream side of the direction in which the medium PM is transported is referred to as the "feed side," and the downstream side is referred to as the "discharge side."

[0016] Additionally, the direction in the horizontal plane perpendicular to the medium feed direction, i.e., the direction in which the rotation axes of the transport rollers 801, 802 extend, is referred to as the "medium width direction." With regard to the "medium width direction," the left and right sides when looking at the feed side from the discharge side in the medium feed direction are referred to as the left and right sides of the medium width direction. The direction perpendicular to the "medium feed direction" and "medium width direction" is referred to as the "up-down direction."

[0017] In the description of the flow path in this specification, the terms "upstream side" and "downstream side" refer to the upstream side and downstream side in the flow direction of the liquid flowing inside.

[0018] Each of the four head units 100 is a so-called line type head, and is supported by a support 100a at both ends in the medium width direction. In this embodiment, the four head units 100 are configured to eject ink of four different colors. As an example, the four colors are cyan, magenta, yellow, and black. The specific structure and function of each of the head units 100 will be described later.

[0019] The platen 700 is a plate-like member that supports the medium PM from the side opposite (below) the head unit 100 when ink is ejected from the head unit 100 toward the medium PM. The width of the platen 700 in the medium width direction is larger than the width of the largest medium on which the printer 1000 can record an image.

[0020] The pair of transport rollers 801, 802 are disposed on either side of the platen 700 in the medium feed direction. The pair of transport rollers 801, 802 transport the medium PM to the discharge side in the medium feed direction in a predetermined manner when an image is formed on the medium PM by the head unit 100. The transport rollers 801, 802 are an example of a "medium transport section" in the present invention.

[0021] The ink tank IT is divided into four sections so as to accommodate four different color inks. The sub-tanks ST and the drain tank DT are provided above each head unit 100, one each.

[0022] The ink tank IT is connected to each of the four sub-tanks ST via an ink flow path member IC1. One ink flow path member IC1 is provided for each sub-tank ST, that is, one for each color.

[0023] 2, each of the four sub-tanks ST is connected to a head system HS1 (described in detail later) included in the head unit 100 via an ink flow path member IC2 so as to supply ink to the corresponding head unit 100. Each of the four drain tanks DT is connected to the head system HS1 of the head unit 100 via an ink flow path member IC3 so as to discharge ink from the corresponding head unit 100. A pump (differential pressure mechanism) PP is provided between the sub-tank ST and the drain tank DT. The head system HS1, the sub-tank ST connected thereto, the drain tank DT, and the pump PP constitute an ink supply system ISS1 of the first embodiment.

[0024] The control device CONT controls each part of the printer 1000 overall, and causes the printer 1000 to perform operations such as forming an image on the medium PM. The control device CONT includes an FPGA (Field Programmable Gate Array), an EEPROM (Electrically Eracable Programmable Read-Only Memory), and a RAM (Random Access Memory). The control device CONT may also include a CPU (Central Processing Unit) or an ASIC (Application Specific Integrated Circuit). The control device CONT is connected to an external device (not shown) such as a PC so as to be able to communicate data with the printer 1000, and controls each part of the printer 1000 based on print data sent from the external device.

[0025] <Head Unit 100> As shown in FIG. 2, the head unit 100 includes a holding member 10 and nine head systems HS1 supported integrally by the holding member 10.

[0026] The holding member 10 is a rectangular plate-like member in a plan view, with the longitudinal direction being the medium width direction and the transverse direction being the medium feed direction. Both ends of the holding member 10 in the longitudinal direction are supported portions that are supported by the support body 100a.

[0027] The nine head systems HS1 are each disposed inside a plurality of openings (not shown) of the holding member 10, and are thereby held together by the holding member 10. The nine head systems HS1 are disposed in a staggered pattern along the medium width direction in a plan view. Each of the head systems HS1 has a plurality of nozzles 3 (described in detail below) at its bottom.

[0028] <Head system HS1> Each of the plurality of head systems HS1 mainly includes an ink supply tube 20, an ink discharge tube 30, a first flow path block 41, a second flow path block 42, a frame member 50, and a head 60, as shown in FIGS.

[0029] <Ink supply pipe 20> The ink supply pipe 20 forms a part of a supply flow path S (FIG. 9) for causing ink in the sub tank ST to flow to the head 60. The ink supply pipe 20 is a branched pipe having one upstream end 20a, a branching portion 20x, and two downstream ends 20b1, 20b2. The upstream end 20a is disposed above the downstream ends 20b1, 20b2.

[0030] The ink supply pipe 20 has an ink supply port SP 20 Ink supply port SP 20 The downstream end of the ink flow path member IC2, the upstream end of which is connected to the sub-tank ST, is connected to the ink flow path member IC2.

[0031] <Ink discharge pipe 30> The ink discharge pipe 30 forms a part of a discharge flow path D (FIG. 9) for causing ink in the head 60 to flow to a drain tank DT. The ink discharge pipe 30 is a branched pipe having two upstream ends 30a1, 30a2, a branched portion 30x, and one downstream end 30b. The downstream end 30b is disposed above the upstream ends 30a1, 30a2.

[0032] The ink discharge pipe 30 has an ink discharge port DP 30 Ink outlet DP 30The upstream end of the ink flow path member IC3, the downstream end of which is connected to the drain tank DT, is connected to the ink flow path member IC4.

[0033] <First and second flow path blocks 41, 42> The first and second flow path blocks (first and second flow path members) 41, 42 form a part of a supply flow path S for causing ink in the subtank ST to flow to the head 60, and a part of a discharge flow path D for causing ink in the head 60 to flow to the drain tank DT. The first and second flow path blocks 41, 42 are disposed downstream of the ink supply pipe 20 and upstream of the ink discharge pipe 30.

[0034] Since the first and second flow path blocks 41 and 42 have the same structure, only the first flow path block 41 will be described here.

[0035] As shown in FIG. 5, the first flow path block 41 mainly includes a flow path forming portion 411 and a pair of lid portions 412 and 413 attached to the flow path forming portion 411.

[0036] The flow path forming portion 411 has a rectangular parallelepiped main body portion MB, two connection pipes CT1 and CT2 protruding upward from an upper surface MBu of the main body portion MB, and four connection pipes CT3, CT4, CT5, and CT6 protruding downward from a lower surface MBd of the main body portion MB.

[0037] The connecting pipe CT1 is located on the discharge side of the center of the upper surface MBu in the medium feed direction, and the connecting pipe CT2 is located on the feed side of the center of the upper surface MBu in the medium feed direction. The four connecting pipes CT3, CT4, CT5, and CT6 are lined up in this order from the discharge side to the feed side in the medium feed direction.

[0038] An inverted V-shaped groove G1 is formed on the right side MBr of the main body MB in the medium width direction. tp (FIG. 5(b)) extends downward and toward the discharge side in the medium feed direction and has a lower end G1 bt1 The first portion G11 leading to the top portion G1 tp Extending downward from the lower end G1 toward the feeding side in the medium feeding direction bt2and a first portion G12 leading to the top portion G1 tp is located in an area on the side MBr closer to the discharge side than the center in the medium feed direction.

[0039] An inverted V-shaped groove G2 is formed on the left side surface MB1 of the main body MB in the medium width direction. The groove G2 has the same shape as the groove G1 when viewed in the medium width direction. Specifically, the groove G2 has a top G2 tp Extending downward from the lower end G2 to the discharge side in the medium feed direction bt1 The first portion G21 leading to the top portion G2 tp Extending downward from the lower end G2 toward the feeding side in the medium feeding direction bt2 and a second portion G22 leading to the top portion G2. tp is located in an area on the feeding side of the center of the side MB1 in the medium feeding direction. That is, the grooves G1 and G2 are formed at positions shifted from each other in the medium feeding direction.

[0040] The extension direction of the first parts G11, G21 and the extension direction of the second parts G12, G22 are inclined at an angle θ with respect to the up-down direction (vertical direction) so that the first parts G11, G21 and the second parts G12, G22 approach each other as they move upward. In this embodiment, the angle θ is about 45°, but it can be set to any angle less than 90°. When the flow path is extended in a direction other than the vertical direction, the flow path is extended in a direction other than the vertical direction, so that the pigment can be prevented from settling on the bottom surface of the flow path by making the flow path extend in this way different from the horizontal direction. In addition, the retention of air bubbles mixed in the ink on the upper surface of the flow path can be prevented, and the ink can be more reliably flowed upward.

[0041] Inside the main body part MB, there is a top G1 tp , lower end G1 bt1 , lower end G1 bt2 In the medium feed direction, the top G2 is formed at a position where the top G2 and the bottom G3 are overlapped with each other. tp , lower end G2 bt1 , lower end G2 bt2 At positions where these overlap, channels ch2, ch4, and ch6 extending in the up-down direction are formed.

[0042] The lower end of the flow channel ch1 is the top G1 of the groove G1. tp The upper end of the flow channel ch3 communicates with the groove G1 through an opening A1 formed in the upper surface of the main body MB, and the upper end of the flow channel ch3 communicates with the connection pipe CT1 on the upper surface MBu of the main body MB. bt1 The upper end of the flow channel ch5 communicates with the groove G1 through an opening A3 formed in the lower surface of the main body MB, and the lower end of the flow channel ch3 communicates with the connection pipe CT3 on the lower surface MBd of the main body MB. bt2 The flow passage ch5 communicates with the recessed groove G1 via an opening A5 formed in the lower surface of the main body portion MB, and the lower end of the flow passage ch5 communicates with a connection pipe CT5 on the lower surface MBd of the main body portion MB.

[0043] The lower end of the flow channel ch2 is the top G2 of the groove G2. tp The upper end of the flow channel ch2 communicates with the groove G2 through an opening A2 formed in the upper surface MBu of the main body MB. bt1 The upper end of the flow channel ch6 communicates with the groove G2 through an opening A4 formed in the lower surface of the main body MB, and the lower end of the flow channel ch4 communicates with the connection pipe CT4 on the lower surface MBd of the main body MB. bt2 The flow passage ch6 communicates with the recessed groove G2 via an opening A6 formed in the lower end of the flow passage ch6, and the lower end of the flow passage ch6 communicates with a connection pipe CT6 on the lower surface MBd of the main body portion MB.

[0044] The lids 412 and 413 are members for covering the grooves G1 and G2 of the main body MB. The lids 412 and 413 are flat plates, and their shape and dimensions in the medium width direction are substantially the same as those of the main body MB. The lids 412 and 413 are attached to the side surfaces MBr and MBl of the main body MB, respectively, with any fastener such as a screw, and cover the grooves G1 and G2. In order to more reliably seal the grooves G1 and G2, an O-ring extending along the contour of the grooves G1 and G2 may be provided between the main body MB and the lids 412 and 413.

[0045] By covering the groove G1 of the main body part MB with the lid part 412, a branch flow path consisting of the connecting pipes CT1, CT3, CT5, the flow paths ch1, ch3, ch5, and the groove G1 is formed inside the first flow path block 41. By covering the groove G2 of the main body part MB with the lid part 413, a branch flow path consisting of the connecting pipes CT2, CT4, CT6, the flow paths ch2, ch4, ch6, and the groove G2 is formed.

[0046] The downstream end 20b1 of the ink supply pipe 20 is connected to the connecting pipe CT1 of the first flow path block 41, and the upstream end 30a1 of the ink discharge pipe 30 is connected to the connecting pipe CT2. The upstream end 30a2 of the ink discharge pipe 30 is connected to the connecting pipe CT1 of the second flow path block 42, and the downstream end 20b2 of the ink supply pipe 20 is connected to the connecting pipe CT2.

[0047] <Frame member 50> The frame member 50 is a structure for connecting the first and second flow path blocks 41, 42 and the head 60, and for fixing them to the support plate 10. The frame member 50 is disposed below the first and second flow path members 41, 42.

[0048] As shown in FIGS. 3 and 6, the frame member 50 is a laminated structure in which an alignment frame 51, a back end frame 52, and a front end frame 53 are laminated in this order from the top.

[0049] The alignment frame 51 is, for example, a flat plate member made of SUS. The alignment frame 51 has a central through hole TH that is rectangular in plan view and penetrates the center from top to bottom. 51 and the central through hole TH 51 Eight through holes for flow passages, which are circular in plan view, are provided around the 51 The through hole for the flow path th 51 is the central through hole TH 51 Four of them are provided on each side in the media width direction, lined up in the media feed direction.

[0050] The back-end frame 52 is, for example, a rectangular member made of resin. The back-end frame 52 has a central through hole TH that is rectangular in plan view and penetrates the center from top to bottom. 52 and the central through hole TH 52 Eight through holes for flow passages, which are circular in plan view, are provided around the 52 The through hole for the flow path th 52 is the central through hole TH 52 Four of them are provided on each side in the media width direction, lined up in the media feed direction.

[0051] The front end frame 53 is, for example, a flat plate member made of SUS. The front end frame 53 has a central through hole TH that is rectangular in plan view and penetrates the center from top to bottom. 53 and the central through hole TH 53 Eight through holes th for flow paths, each of which is substantially rectangular in plan view, are provided around the 53 The through hole for the flow path th 53 is the central through hole TH 53 Four of them are provided on each side in the media width direction, lined up in the media feed direction.

[0052] When the alignment frame 51, the back-end frame 52, and the front-end frame 53 are stacked in this order from the top, the central through hole TH 51 , the central through hole TH of the back end frame 52 52 , and the central through hole TH of the front end frame 53 53 The eight through holes th 51 Each of the eight through holes th for flow passages in the back end frame 52 52 and the eight flow passage through holes th of the front end frame 53 53 These are connected to each other to form eight through holes th for flow paths (FIG. 4).

[0053] The frame member 50 is fixed to the support plate 10 via an alignment frame 51 .

[0054] The connecting pipes CT3 to CT6 of the first flow path block 41 are inserted into four through holes th for flow paths formed on the left side of the central through hole TH in the medium width direction, and the connecting pipes CT3 to CT6 of the second flow path block 42 are inserted into four through holes th for flow paths formed on the right side of the central through hole TH in the medium width direction. An O-ring (not shown) may be disposed between the inner peripheral surface of the through hole th for flow paths and the outer peripheral surface of the connecting pipes CT3 to CT6.

[0055] <Head 60> As shown in FIGS. 6, 7 and 8, the head 60 includes a flow passage unit 61, a piezoelectric actuator 62, and a discharge control unit 63.

[0056] 8, the flow path unit 61 is a laminated structure in which an ink sealing film 61A, plates 61B to 61E, and a nozzle plate 61F are laminated in this order from the top. Inside the flow path unit 61, a flow path CH (FIG. 7) is formed by removing a portion of each of the plates 61B to 61E and the nozzle plate 61F.

[0057] As shown in FIG. 7 and FIG. 8, the flow channel CH has eight ink flow ports CP 61 The manifold flow paths M1, M2, M3, and M4 include four manifold flow paths M1, M2, M3, and M4, and 48 individual flow paths ICH.

[0058] 8 ink flow ports CP 61 The eight ink flow ports CP are arranged in a line in the medium feed direction, four at each end of the flow passage unit 61 in the medium width direction. 61 Each of these is formed by providing a through hole coaxially in the ink sealing film 61A and the plates 61B and 61C.

[0059] Each of the four manifold flow paths M1 to M4 is a linear flow path extending in the medium width direction. That is, the four manifold flow paths M1 to M4 extend parallel to one another. The four manifold flow paths M1 to M4 are provided in this order from the discharge side to the feed side in the medium feed direction.

[0060] Each of the four manifold flow paths M1 to M4 is formed by removing a portion of the plate 61D. That is, the four manifold flow paths M1 to M4 are formed at the same position in the vertical direction. The top surfaces Mt of the four manifold flow paths M1 to M4 are flush with one another, and the bottom surfaces Md of the four manifold flow paths M1 to M4 are flush with one another.

[0061] Each of the manifold flow paths M1 to M4 has an ink flow port CP 61 It is connected to.

[0062] Each of the 48 individual channels ICH includes a pressure chamber 1, a descender channel 2, and a nozzle 3, as shown in FIG.

[0063] The pressure chamber 1 is a space for applying pressure to ink by the piezoelectric actuator 62, and is formed by removing a part of the plate 61B. The upper surface of the pressure chamber 1 is formed by an ink sealing film 61A. The shape of the pressure chamber 1 in a plan view is an ellipse that is long in the medium feed direction (FIG. 7), with a flow path that extends to the manifold flow path M1 (or any of the manifold flow paths M2 to M4) connected to the vicinity of one of the arc portions, and a descender flow path 2 connected to the vicinity of the other arc portion.

[0064] The descender flow paths 2 are flow paths that allow ink in the pressure chambers 1 to flow to the nozzles 3, and are formed by providing circular through holes coaxially in each of the plates 61C to 61E. The descender flow paths 2 extend in the vertical direction from the pressure chambers 1 to the nozzles 3.

[0065] The nozzles 3 are minute openings that eject ink toward the medium PM, and are formed in the nozzle plate 61F.

[0066] The individual flow channels ICH are connected to each of the four manifold flow channels M1 to M4, 12 of which are arranged in an individual flow channel row L arranged in the medium width direction by the 12 individual flow channels ICH connected to one manifold flow channel. ICH In addition, one individual flow path array LICH The nozzles 3 of the twelve individual flow channels ICH form a nozzle row L3. ICH The pressure chambers 1 of the individual flow channels ICH included in each individual flow channel array L are connected only to the corresponding manifold flow channels and are not connected to other manifold flow channels. ICH To the pressure chambers 1 of the individual channels ICH included in the manifold, only ink is supplied via the corresponding manifold channel. In this embodiment, each nozzle 3 included in a given nozzle row L3 and each nozzle 3 included in a nozzle row L3 adjacent to the given nozzle row are provided at positions slightly offset in the medium width direction.

[0067] As shown in Figure 8, the piezoelectric actuator 62 is composed of a first piezoelectric layer 621 provided on the upper surface of the flow path unit 61, a second piezoelectric layer 622 above the first piezoelectric layer 621, a common electrode 623 sandwiched between the first piezoelectric layer 621 and the second piezoelectric layer 622, and a number of individual electrodes 624 provided on the upper surface of the second piezoelectric layer 622.

[0068] The first piezoelectric layer 621 is provided on the upper surface of the ink sealing film 61A so as to cover all of the multiple individual channels ICH formed in the channel unit 61. A common electrode 623 is provided on the upper surface of the first piezoelectric layer 621 so as to cover almost the entire upper surface of the first piezoelectric layer 621, and a second piezoelectric layer 622 is provided on the upper surface of the common electrode 623 so as to cover the entire areas of the first piezoelectric layer 621 and the common electrode 623.

[0069] The common electrode 623 is grounded via a wiring (not shown) and is always maintained at the ground potential.

[0070] Each of the individual electrodes 624 has a generally rectangular planar shape with the medium feed direction as the longitudinal direction. The individual electrodes 624 are provided on the upper surface of the second piezoelectric layer 622 so as to be located above the pressure chambers 1 of the individual channels ICH. Each of the individual electrodes 624 is aligned so as to be located above the center of the corresponding pressure chamber 1.

[0071] In a structure in which the first piezoelectric layer 621, the second piezoelectric layer 622, the common electrode 623, and the multiple individual electrodes 624 are arranged as described above, the portions of the second piezoelectric layer 622 sandwiched between the common electrode 623 and each of the multiple individual electrodes 624 become active portions 622a polarized in the thickness direction.

[0072] As shown in FIG. 6, the discharge control unit 63 includes a holding plate 631, an FPC (Flexible Printed Circuits) 632 wrapped around the holding plate 631, and two driver ICs 633 mounted on the FPC 632.

[0073] A plurality of contacts (not shown) are formed on a portion of the FPC 632 located on the lower surface 631d side of the holding plate 631. Two driver ICs 633 are mounted on a portion of the FPC 632 located on the upper surface 631u side of the holding plate 631.

[0074] The ejection control unit 63 is disposed on the upper surface of the piezoelectric actuator 62 such that each of the contacts of the FPC 632 is electrically connected to each of the individual electrodes 624 of the piezoelectric actuator 62. As a result, each of the individual electrodes 624 of the piezoelectric actuator 62 is connected to the driver IC 633 via the FPC 632. Specifically, the driver IC 633 disposed on the right side in the medium width direction is connected to the individual electrode 624 located to the right of the center in the medium width direction, and the driver IC 633 disposed on the left side in the medium width direction is connected to the individual electrode 624 located to the left of the center in the medium width direction. In addition, the driver IC 633 is connected to the control unit CONT via wiring (not shown).

[0075] The head 60 is fixed to the lower surface 53d (FIG. 4) of the front end frame 53 of the frame member 50. In this state, the eight ink circulation ports CP 61 Each of the eight through holes TH communicates with the eight flow passage through holes th. The piezoelectric actuator 62 and the discharge control section 63 are disposed inside the central through hole TH.

[0076] <Flow path configuration of ink supply system ISS1> The flow paths formed by the ink supply system ISS1 including the head system HS1 having the above configuration will be summarized with reference to FIG.

[0077] A supply flow path S for sending ink from the subtank ST to the head 60 is formed by the ink supply tube 20, a flow path extending from the connecting tube CT1 of the first flow path block 41 to the connecting tubes CT3 and CT5, a flow path extending from the connecting tube CT2 of the second flow path block 42 to the connecting tubes CT4 and CT6, and a flow path through hole th of the frame member 50.

[0078] The ink supply port SP at the upstream end 20a of the ink supply tube 20 is connected to the sub tank ST via the ink flow path member IC2. 20 The ink supplied to the ink supply pipe 20 flows through the ink supply pipe 20 to the branch 20x, and then splits into two, one flowing toward the downstream end 20b1 of the ink supply pipe 20 and the first flow path block 41, and the other flowing toward the downstream end 20b2 of the ink supply pipe 20 and the second flow path block 42.

[0079] The ink flowing toward the first flow path block 41 passes through a connection pipe CT1 connected to the downstream end 20b1 of the ink supply pipe 20, reaches the recessed groove G1, and reaches the top G1 of the recessed groove G1. tp In this case, it is divided into two.

[0080] One of the two separated ink flows through the first portion G11 of the groove G1, the flow path ch3, the connection pipe CT3, the flow path through hole th of the frame member 50, and the ink flow port CP 61 The other of the two split ink flows through the second portion G12 of the groove G1, the flow channel ch5, the connection pipe CT5, the frame The through hole th for the flow passage of the head member 50, the third ink flow port CP 61 Then, it flows into manifold M3.

[0081] The ink flowing toward the second flow path block 42 passes through the connection pipe CT2 connected to the downstream end 20b2 of the ink supply pipe 20, reaches the groove G2, and reaches the top G2 of the groove G2. tp In this case, it is divided into two.

[0082] One of the two separated ink flows through the first portion G21 of the groove G2, the flow path ch4, the connection pipe CT4, the flow path through hole th of the frame member 50, and the ink flow port CP 10 , which is the second ink flow port from the right side in the medium width direction and the discharge side end in the medium feed direction of the head 60. 61 The other of the two split ink flows through the second portion G22 of the groove G2, the flow passage ch6, the connection pipe CT6, the flow passage through hole th of the frame member 50, and the fourth ink flow port CP 61 Then, it flows into manifold M4.

[0083] The discharge flow path D for sending ink from the head 60 to the drain tank DT is formed by the ink discharge pipe 30, a flow path extending from the connecting tube CT2 of the first flow path block 41 to the connecting tubes CT4 and CT6, a flow path extending from the connecting tube CT1 of the second flow path block 42 to the connecting tubes CT3 and CT5, and the flow path through hole th of the frame member 50.

[0084] Through the manifold M1, an ink flow port CP 61 The ink that has reached the ink passage passes through the flow passage through hole th of the frame member 50, and flows into the second flow passage block from the connection pipe CT3 of the second flow passage block 42. The ink passes through the manifold M3 and flows to the ink passage port CP 61 The ink that has reached the ink passage passes through the through hole th of the frame member 50 and flows into the second flow path block from the connection pipe CT5 of the second flow path block 42. tp , and passes through the connection pipe CT1 of the second flow path block 42 and the ink discharge pipe 30 to the ink discharge port DP 30 from there to the drain tank DT.

[0085] Through the manifold M2, the ink flow port CP is located on the left side in the media width direction and second from the end on the discharge side in the media feed direction. 61 The ink that has reached the first flow path passes through the flow path through hole th of the frame member 50, and flows into the first flow path block from the connection pipe CT4 of the first flow path block 41. The ink passes through the manifold M4 and flows to the fourth ink flow port CP 61 The ink that has reached the ink passage passes through the through hole th of the frame member 50 and flows into the first flow path block from the connection pipe CT6 of the first flow path block 41. tp , and passes through the connection pipe CT2 of the first flow path block 41 and the ink discharge pipe 30 to the ink discharge port DP 30 from there to the drain tank DT.

[0086] The directions in which ink flows in the supply flow path S, the manifolds M1 to M4, and the discharge flow path D are as shown by the arrows in Fig. 9. As shown in Fig. 9, in an ink supply system ISS1 including the head system HS1 of this embodiment, in the manifolds M1 and M3, ink flows toward the right in the medium width direction, and in the manifolds M2 and M4, ink flows toward the left in the medium width direction. That is, in two manifolds that are adjacent to each other without another manifold in between in the medium feed direction, ink flows in opposite directions to each other. The reason for flowing ink in this manner will be described later.

[0087] Here, the flow path formed between the upstream end 20a of the ink supply pipe 20 and the branch 20x is a common supply flow path S0. The flow path leading to the head 60 is a first supply branch flow path S1, and the flow path leading to the head 60 via the second flow path block 42 is a second supply branch flow path S2.

[0088] The ink supply pipe 20 and the first and second flow path blocks 41, 42 may be configured so that the flow path resistance of the first supply branch flow path S1 is the same as the flow path resistance of the second supply branch flow path S2. Specifically, for example, the ink supply pipe 20 and the first and second flow path blocks 41, 42 may be configured so that the flow path length of the first supply branch flow path S1 is the same as the flow path length of the second supply branch flow path S2, and the cross-sectional area of ​​the first supply branch flow path S1 (cross-sectional area of ​​a plane perpendicular to the flow path extension direction) is the same as the cross-sectional area of ​​the second supply branch flow path S2. This makes the amount of ink sent from the branch 20x to the first and second supply branch flow paths S1, S2 equal (equal amount branching is possible), and ink can flow at a stable flow rate. This also makes the flow speed of the ink flowing through the manifolds M1 and M3 the same as the flow speed of the ink flowing through the manifolds M2 and M4, thereby more effectively eliminating temperature unevenness in the ink flowing through the manifolds M1 to M4, and ultimately, density unevenness in image formation (described in more detail below).

[0089] In the first supply branch flow path S1, the branch 20x of the ink supply pipe and the top G1 of the groove G1 of the first flow path block 41 tp The flow path formed between the first common supply branch flow path S 10 and the top G1 tp The flow paths between the manifolds M1 and M3 are the first and third branch supply tributary flow paths S 11 , S 13 In the second supply branch flow path S2, the branch 20x of the ink supply pipe and the top G2 of the groove G2 of the second flow path block 42 tp The flow path formed between the first and second common supply tributary paths S 20 and the top G2 tp The flow paths between the manifolds M2 and M4 are the second and fourth branch supply tributary flow paths S 22 , S 24 The grooves G1 and G2 of the first and second flow path blocks 41 and 42 have a first portion G11 and a second portion G12 extending in a direction different from the vertical direction and intersecting a plane (horizontal plane) including the medium width direction and the medium feed direction, and the flow path length of the first, second, third, and fourth branch supply tributary flow paths S 11 , S 22 , S 13 , S 24The length of the flow passage may be more than half of the length of the flow passage.

[0090] In addition, the flow path formed between the downstream end 30b of the ink discharge tube 30 and the branch 30x is a common discharge flow path D0, the flow path from the branch 30x of the ink discharge tube 30 to the head 60 via the first flow path block 41 is a first discharge tributary flow path D1, and the flow path to the head 60 via the second flow path block 42 is a second discharge tributary flow path D2.

[0091] The ink discharge pipe 30 and the first and second flow path blocks 41, 42 may be configured so that the flow path resistance of the first discharge tributary flow path D1 is the same as the flow path resistance of the second discharge tributary flow path D2. Specifically, for example, the ink discharge pipe 30 and the first and second flow path blocks 41, 42 may be configured so that the flow path length of the first discharge tributary flow path D1 is the same as the flow path length of the second discharge tributary flow path D2, and the cross-sectional area of ​​the first discharge tributary flow path D1 (cross-sectional area of ​​a plane perpendicular to the flow path extension direction) is the same as the cross-sectional area of ​​the second discharge tributary flow path D2. This makes the amount of ink sent from the first and second discharge tributary flow paths D1, D2 to the branch 30x equal, allowing the ink to flow at a stable flow rate. This also makes the flow speed of the ink flowing through the manifolds M1 and M3 the same as the flow speed of the ink flowing through the manifolds M2 and M4, thereby more effectively eliminating temperature unevenness in the ink flowing through the manifolds M1 to M4, and ultimately, density unevenness in image formation (described in more detail below).

[0092] In the first discharge branch flow path D1, the branch 30x of the ink discharge pipe and the top G2 of the recessed groove G2 of the first flow path block 41 tp The flow path formed between the first common exhaust tributary flow path D 10 and the top G2 tp The flow paths between the manifolds M2 and M4 are the second and fourth branch exhaust tributary flow paths D 12 , D 14 In the second discharge branch flow path D2, the branch 30x of the ink discharge pipe 30 and the top G1 of the recessed groove G1 of the second flow path block 42 tp The flow path formed between the 20 and the top G1 tpThe flow paths between the manifolds M1 and M3 are the first and third branch exhaust tributary flow paths D 21 , D 23 The grooves G1 and G2 of the first and second flow path blocks 41 and 42 have a first portion G11 and a second portion G12 extending in a direction different from the vertical direction and intersecting a plane (horizontal plane) including the medium width direction and the medium feed direction, and the flow path length of the first, second, third, and fourth branch discharge tributary flow paths D 21 , D 12 , D 23 , D 14 The length of the flow passage may be more than half of the length of the flow passage.

[0093] In addition, in consideration of manufacturing errors of each part constituting the flow path, assembly errors of each part constituting the flow path, errors due to shape changes of each part (deformation of resin pipes, etc.) that may occur during assembly, etc., it is not necessarily easy or necessary to make the flow path resistance of the two flow paths completely the same. In this embodiment, for example, if the error of the flow path resistance of the first supply branch flow path S1 relative to the flow path resistance of the second supply branch flow path S2 is within 10% of the flow path resistance of the second supply branch flow path S2, equal branching can be realized and density unevenness (described in detail later) in image formation can be suppressed well. Similarly, if the error of the flow path resistance of the first discharge branch flow path D1 relative to the flow path resistance of the second discharge branch flow path D2 is within 10% of the flow path resistance of the second discharge branch flow path D2, equal branching can be realized and density unevenness (described in detail later) in image formation can be suppressed well.

[0094] In this specification and the present invention, the flow resistance of a certain flow path is the same as the flow resistance of another flow path means that the error of the flow resistance of a certain flow path relative to the flow resistance of the other flow path is within 10% of the flow resistance of the other flow path. The cross-sectional area of ​​a certain flow path is the same as the cross-sectional area of ​​another flow path means that the error of the cross-sectional area of ​​a certain flow path relative to the cross-sectional area of ​​the other flow path is less than 10% of the cross-sectional area of ​​the other flow path. The flow length of a certain flow path is the same as the flow length of another flow path means that the error of the flow length of a certain flow path relative to the flow length of the other flow path is less than 10% of the flow length of the other flow path. When comparing the cross-sectional area of ​​a certain flow path with the cross-sectional area of ​​another flow path, if the cross-sectional area is not constant throughout the flow path, the average value of the cross-sectional area throughout the flow path may be used. In addition, the flow velocity of a liquid flowing through a certain flow path is the same as the flow velocity of a liquid flowing through another flow path means that the error of the flow velocity of a liquid flowing through a certain flow path relative to the flow velocity of a liquid flowing through the other flow path is within 10% of the flow velocity of the liquid flowing through the other flow path.

[0095] <Image forming method> An image is formed on the medium PM using the printer 1000 and the head unit 100 as follows.

[0096] First, the medium PM in a feed tray (not shown) is sent to the feed side of the transport rollers 801, and is then sent by the transport rollers 801 onto the platen 700. The multiple head systems HS1 of the head unit 100 continuously eject ink droplets onto the medium PM being sent in the medium feed direction by the transport rollers 801, 802, forming an image on the medium PM. The medium PM with the image formed thereon is sent to the discharge side of the transport rollers 802, and is discharged to a discharge tray (not shown).

[0097] The ejection of ink droplets using the head system HS1 is performed by applying pressure to the ink in a predetermined pressure chamber 1 (referred to as a "target pressure chamber") using a piezoelectric actuator 62. Specifically, first, under the command of the control device CONT, the driver IC 633 applies a driving potential to the individual electrode 624 corresponding to the target pressure chamber via the FPC 632. As a result, an electric field parallel to the polarization direction is generated in the active portion 622a sandwiched between the individual electrode 624 to which the driving potential is applied and the common electrode 623, and the active portion 622a contracts in a horizontal direction perpendicular to the polarization direction. As a result, the ink sealing film 61A above the target pressure chamber vibrates, pressure is applied to the ink in the target pressure chamber, and ink droplets are ejected from the nozzle 3 communicating with the pressure chamber 1 via the descender flow path 2.

[0098] Ink in the subtank ST is continuously supplied to the pressure chamber 1 via the supply flow path S and manifolds M1 to M4. Furthermore, of the ink in the manifolds M1 to M4, the ink that is not supplied to the pressure chamber 1 is sent to the drain tank DT via the discharge flow path D. The flow of ink from the subtank ST to the drain tank DT via the supply flow path S and discharge flow path D is generated by, for example, a pump PP. Furthermore, the ink returned to the drain tank DT is returned to the subtank ST by the pump PP via a filter (not shown).

[0099] In the head system HS1 of this embodiment, the direction of ink flow in the manifolds M1 and M3 and the direction of ink flow in the manifolds M2 and M4 are The reasons for their opposition to each other are as follows:

[0100] Generally, the ink ejected from the nozzles of the head experiences a temperature drop in the flow path from the ink tank to the nozzles. This is because the outside air temperature is lower than the optimum temperature for the ink (for example, about 40°C).

[0101] The inventors of the present invention have found that such a drop in the temperature of the ink can cause a decrease in the quality of the formed image, specifically for the following reasons.

[0102] Ink is a liquid and its viscosity changes depending on the temperature, and in an individual flow path to which ink with a lower temperature and higher viscosity is supplied, the amount of ink ejected from the nozzle in response to the application of pressure in the pressure chamber may decrease. Because the temperature of the ink gradually decreases in the flow path leading from the ink tank to the pressure chamber, ink with a lower temperature (higher viscosity) is supplied to the pressure chamber located further downstream. In this way, when high-viscosity ink is supplied to a specific pressure chamber, the amount of ink ejected from that pressure chamber decreases, and this may result in quality degradation such as uneven density in the image formed on the medium PM.

[0103] As a specific example, consider a case where ink is made to flow in the same direction through all of the manifolds M1 to M4 shown in Fig. 7. If ink is made to flow from the left to the right in the medium width direction through all of the manifolds M1 to M4, relatively high temperature ink is supplied to the individual flow paths ICH near the left end on the upstream side, and relatively low temperature ink is supplied to the individual flow paths ICH near the right end on the downstream side. Therefore, the amount of ink ejected from the nozzles 3 of the individual flow paths ICH near the right end is smaller than the amount of ink ejected from the nozzles 3 of the individual flow paths ICH near the left end, causing density unevenness in the formed image.

[0104] In contrast, the head system HS1 of the first embodiment supplies and discharges ink to and from the head 60 so that the direction of the ink flow in the manifolds M1 and M3 is opposite to the direction of the ink flow in the manifolds M2 and M4. This offsets density unevenness in the image formed by the nozzle row L3 corresponding to each manifold.

[0105] Considering the manifold M1 and the manifold M2 specifically, in the manifold M1, a relatively high temperature ink is supplied to the individual flow channel ICH connected to the manifold M1 on the left side (upstream side) in the medium width direction, and a relatively low temperature ink is supplied to the individual flow channel ICH connected to the manifold M1 on the right side (downstream side) in the medium width direction. ICHAn image formed by ejecting ink from nozzle row L3 tends to have a high density on the left side in the medium width direction and a decrease in density toward the right side.

[0106] On the other hand, in the manifold M2, ink of a relatively high temperature is supplied to the individual flow passage ICH connected to the manifold M2 on the right side (upstream side) in the medium width direction, and ink of a relatively low temperature is supplied to the individual flow passage ICH connected to the manifold M2 on the left side (downstream side) in the medium width direction. ICH An image formed by ejecting ink from nozzle row L3 has a tendency to have a high density on the right side in the medium width direction and a decrease in density toward the left side.

[0107] Here, since the nozzle row L3 connected to the manifold M1 and the nozzle row L3 connected to the manifold M2 are close to each other, in the image formed on the medium PM, the density unevenness of the image formed by the nozzle row L3 connected to the manifold M1 and the density unevenness of the image formed by the nozzle row L3 connected to the manifold M2 are offset to a certain extent. That is, the image formed by the nozzle row L3 connected to the manifold M1, which is darkest at the left end in the medium width direction and tends to become lighter toward the right side in the medium width direction, and the image formed by the nozzle row L3 connected to the manifold M2, which is darkest at the right end in the medium width direction and tends to become lighter toward the left side in the medium width direction, are formed close to each other, so that the density unevenness of both images is averaged, and the density unevenness is eliminated or suppressed overall.

[0108] In this way, in the head system HS1 of the first embodiment, the deterioration of image quality is suppressed by combining the density of an image formed by a certain nozzle and the density of an image formed by a nozzle adjacent to the certain nozzle. Here, a certain nozzle is connected only to a corresponding single manifold and is not connected to other manifolds. In addition, a nozzle adjacent to a certain nozzle is also connected only to a corresponding single manifold and is not connected to other manifolds. The manifold to which a certain nozzle is connected and the manifold to which a nozzle adjacent to the certain nozzle is connected are different manifolds adjacent to each other. That is, the averaging of the density unevenness in the head system HS1 of the first embodiment is performed between nozzles that do not share a manifold. In addition, the averaging of the density unevenness in the head system HS1 of the first embodiment is performed by bringing inks ejected from adjacent nozzles close to or overlapping each other outside the head 60, specifically on the medium PM, rather than by merging inks of different temperatures inside the head 60. This makes it possible to suppress the deterioration of image quality without causing the flow path structure to become complicated and the head to become larger accordingly.

[0109] A similar cancellation (averaging) of density unevenness is performed between the manifolds M2 and M3, and between the manifolds M3 and M4.

[0110] The effects of the head system HS1 of the first embodiment are summarized below.

[0111] The supply flow path S and discharge flow path D of the head system HS1 of the first embodiment are configured to supply and discharge ink in opposite directions to the manifolds arranged adjacent to each other in the medium feed direction of the head 60. Therefore, density unevenness that may occur in an image formed by the nozzle rows L3 corresponding to each manifold can be offset between the manifolds adjacent in the medium feed direction (between the nozzle rows adjacent in the medium feed direction), and deterioration in the quality of the formed image can be suppressed.

[0112] In the head system HS1 of the first embodiment, all of the manifolds M1 to M4 of the head 60 are linear and extend in the medium width direction. Therefore, the flow path length is shorter than that of a manifold that is U-shaped in a plan view and extends from an ink supply port (upstream end) to one side in the medium width direction and then turns back to extend to the ink discharge side (downstream end). Therefore, the difference in temperature between the ink supplied to the pressure chamber connected near the upstream end of the manifold and the ink supplied to the pressure chamber connected near the downstream end of the manifold is small, and deterioration of image quality according to changes in ink temperature is suppressed.

[0113] In the head system HS1 of the first embodiment, the first, second, third, and fourth branch supply tributary channels S 11 , S 22 , S 13 , S 24 , and the first, second, third, and fourth branch exhaust tributary channels D of the exhaust channel D 21 , D 12 , D 23 , D 14 are formed by the first and second flow path blocks 41, 42. In this way, by forming the region where the second stage branching is performed and the number of flow paths is greatest among the supply flow paths S and the discharge flow paths D inside a block-shaped member, the flow paths can be efficiently arranged in the limited space on the head 60, and the head system HS1 can be made compact.

[0114] The ink supply system ISS, the printing apparatus 1000, and the ink distribution method of the first embodiment also achieve the same effects as the head system HS1.

[0115] [Variation 1-1] Next, a head system HS1' according to modified example 1-1 will be described with reference to FIGS. 10(a), 10(b) and 11. FIG.

[0116] The head system HS1' of the modified example 1-1 includes first and second flow path blocks 41' and 42' (FIGS. 10(a) and 10(b)) instead of the first and second flow path blocks 41 and 42 included in the head system HS1 of the first embodiment. Since the other points are the same as those of the head system HS1 of the first embodiment, the description thereof will be omitted.

[0117] The first and second flow path blocks 41', 42' differ from the first and second flow path blocks 41, 42 in that the second portion G12 of the groove G1 is connected to the flow path ch6, and the second portion G22 of the groove G2 is connected to the flow path ch5.

[0118] Specifically, the lower end of the flow channel ch1 is located at the top G1 of the groove G1. tp The upper end of the flow channel ch3 communicates with the groove G1 through an opening A1 formed in the upper surface of the main body MB, and the upper end of the flow channel ch3 communicates with the connection pipe CT1 on the upper surface MBu of the main body MB. bt1 The upper end of the flow channel ch6 communicates with the groove G1 through an opening A3 formed in the lower surface of the main body MB, and the lower end of the flow channel ch3 communicates with the connection pipe CT3 on the lower surface MBd of the main body MB. bt2 The flow passage ch6 communicates with the recessed groove G1 via an opening A6 formed in the lower end of the flow passage ch6, and the lower end of the flow passage ch6 communicates with a connection pipe CT6 on the lower surface MBd of the main body portion MB.

[0119] The lower end of the flow channel ch2 is the top G2 of the groove G2. tp The upper end of the flow channel ch2 communicates with the groove G2 through an opening A2 formed in the upper surface MBu of the main body MB. bt1 The upper end of the flow channel ch5 communicates with the groove G2 through an opening A4 formed in the lower surface of the main body MB, and the lower end of the flow channel ch4 communicates with the connection pipe CT4 on the lower surface MBd of the main body MB. bt2 The flow passage ch5 communicates with the recessed groove G2 via an opening A5 formed in the lower end of the flow passage ch5, and the lower end of the flow passage ch5 communicates with a connection pipe CT5 on the lower surface MBd of the main body portion MB.

[0120] In the first and second flow path blocks 41' and 42', the flow path length of the first portion G11 of the groove G1 is shorter than the flow path length of the second portion G12. Therefore, the cross-sectional area of ​​the second portion G12 is larger than the cross-sectional area of ​​the first portion G11 so that the flow path resistance of the first portion G11 and the flow path resistance of the second portion G12 are equal. Similarly, the cross-sectional area of ​​the second portion G22 is smaller than the cross-sectional area of ​​the first portion G21 of the groove G2 so that the flow path resistance of the first portion G21 and the flow path resistance of the second portion G22 are equal.

[0121] The first and second flow path blocks 41', 42' may be of any configuration in which a flow path is formed on one side of the main body portion MB connecting one of the flow paths ch1, ch2 to flow path ch3 and flow path ch6, and a flow path is formed on the other side of the main body portion MB connecting the other of the flow paths ch1, ch2 to flow path ch4 and flow path ch5.

[0122] An ink supply system ISS1' of modified example 1-1 including a head system HS1' of modified example 1-1 has first and second flow path blocks 41', 42' instead of the first and second flow path blocks 41, 42, thereby configuring supply flow paths S', D' (FIG. 11) instead of the supply flow path S and the discharge flow path D. The supply flow path S' and the discharge flow path D' are configured to flow ink from the left to the right in the medium width direction for the manifolds M1, M4, and to flow ink from the right to the left in the medium width direction for the manifolds M2, M3.

[0123] Specifically, as shown in FIG. 11, the ink flowing from the sub tank ST toward the first flow path block 41′ passes through the top G1 of the groove G1. tp One flows into the manifold M1 via the first portion G11 of the groove G1, the flow path ch3, and the connecting pipe CT3, and the other flows into the manifold M4 via the second portion G12 of the groove G1, the flow path ch6, and the connecting pipe CT6. The ink flowing from the subtank ST toward the second flow path block 42' flows into the top G2 tpOne flows into the manifold M2 via the first portion G21 of the groove G2, the flow path ch4, and the connecting pipe CT4, and the other flows into the manifold M3 via the second portion G22 of the groove G2, the flow path ch5, and the connecting pipe CT5.

[0124] The ink that has flowed into the second flow path block 42' from the connection pipe CT3 of the second flow path block 42' via the manifold M1, and the ink that has flowed into the second flow path block 42' from the connection pipe CT6 of the second flow path block 42' via the manifold M4, contacts the top G1 of the recessed groove G1 of the second flow path block 42'. tp The ink flows through the manifold M2 and the connecting pipe CT4 of the first flow path block 41' into the first flow path block 41', and the ink flows through the manifold M3 and the connecting pipe CT5 of the first flow path block 41' into the first flow path block 41'. tp The two flows are joined at and sent to the drain tank DT via the connecting pipe CT2 of the first flow path block 41'.

[0125] Here, the flow path formed between the upstream end 20a of the ink supply tube 20 and the branch 20x is a common supply flow path S0', the flow path from the branch 20x of the ink supply tube 20 to the head 60 via the first flow path block 41' is a first supply branch flow path S1', and the flow path to the head 60 via the second flow path block 42' is a second supply branch flow path S2'.

[0126] In the first supply branch flow path S1', the branch 20x of the ink supply pipe and the top G1 of the groove G1 of the first flow path block 41 tp The flow path formed between the first common supply branch flow path S 10 ' and the top G1 tp The flow paths between the manifolds M1 and M4 are the first and third branch supply tributary flow paths S 11 ', S 13 In the second supply branch flow path S2', the branch 20x of the ink supply pipe and the top G2 of the groove G2 of the second flow path block 42' tpThe flow path formed between the first and second common supply tributary paths S 20 ' and the top G2 tp The flow paths between the manifolds M2 and M3 are the second and fourth branch supply tributary flow paths S 22 ', S 24 ' is.

[0127] In addition, the flow path formed between the downstream end 30b of the ink discharge tube 30 and the branch 30x is a common discharge flow path D0', the flow path from the branch 30x of the ink discharge tube 30 to the head 60 via the first flow path block 41' is a first discharge tributary flow path D1', and the flow path to the head 60 via the second flow path block 42' is a second discharge tributary flow path D2'.

[0128] In the first discharge branch channel D1', the branch 30x of the ink discharge pipe and the top G2 of the groove G2 of the first channel block 41' tp The flow path formed between the first common exhaust tributary flow path D 10 ' and the top G2 tp The flow paths between the manifolds M2 and M3 are the second and fourth branch exhaust tributary flow paths D 12 ', D 14 In the second discharge branch flow path D2', the branch 30x of the ink discharge pipe 30 and the top G1 of the recessed groove G1 of the second flow path block 42' tp The flow path formed between the 20 ' and the top G1 tp The flow paths between the manifolds M1 and M4 are the first and third branch exhaust tributary flow paths D 21 ', D 23 ' is.

[0129] In the head system HS1' of variant example 1-1, a mechanism similar to that of the head system HS1 of the first embodiment is used to cancel out (average) density unevenness between manifold M1 and manifold M2, and between manifold M3 and manifold M4, thereby suppressing deterioration in the quality of the image formed.

[0130] The following modified embodiments can also be used in the head system HS1 of the first embodiment and the head system HS1' of the modified embodiment. Although the following modified embodiments are described for the head system HS1 of the first embodiment, similar modifications can also be used in the head system HS1' of the modified embodiment 1-1.

[0131] In the supply flow path S of the head system HS1 of the first embodiment, the common supply flow path S0 is branched at 20x into first and second common supply branch flow paths S 10 , S 20 This is further divided into first, second, third and fourth branch supply tributary channels S in the first and second channel blocks 41 and 42. 11 , S 22 , S 13 , S 24 The supply flow path S may have any configuration in which ink is supplied to the manifolds M1 and M3 from one side in the medium width direction, and ink is supplied to the manifolds M2 and M4 from the other side in the medium width direction.

[0132] Specifically, for example, the common supply flow path S0 is branched into four, that is, the first, second, third, and fourth branch supply tributary flow paths S are provided at the downstream end of the common supply flow path S0. 11 , S 22 , S 13 , S 24 Such a flow path may be formed, for example, by using a tubular member that branches into four on the path, instead of the ink supply pipe 20 and the first and second flow path blocks 41 and .

[0133] The same applies to the discharge flow path D of the head system HS1 of the first embodiment.

[0134] In the head system HS1 of the first embodiment, a tubular member branching into two on the path may be used instead of the first and second flow path members 41 and 42. Furthermore, the entire area of ​​the supply flow path S and / or the discharge flow path D may be formed of a tubular member such as a resin tube.

[0135] In the head system HS1 of the first embodiment, a common supply flow path S0 and first and second common supply branch flow paths S 10 , S 20 The common supply flow path S0 and the first and second common supply branch flow paths S 10 , S 20 For example, they may be formed inside the first and second flow path blocks 41 and 42. Also, the entire area of ​​the supply flow path S and / or the discharge flow path D may be formed inside a block-shaped member.

[0136] In the head system HS1 of the first embodiment, the first and second flow path members 41, 42 may be formed as an integrated member.

[0137] The head system HS1 of the first embodiment is configured to distribute ink through four manifolds, but is not limited to this. The head system HS1 may be configured to distribute ink through two manifolds, or may be configured to distribute ink through any even number of manifolds, such as six or eight. If the number of manifolds through which ink flows from one side to the other side in the medium width direction is the same as the number of manifolds through which ink flows from the other side to one side in the medium width direction, temperature unevenness of the ink flowing through the manifolds, and therefore density unevenness in image formation, are more effectively eliminated.

[0138] A modified embodiment in which ink flows in opposite directions through two manifolds adjacent in the medium feed direction can be obtained, for example, by omitting the second portion G12 of groove G1, the second portion G22 of groove G2, and the connecting pipes CT5 and CT6 in the first flow path member 41 and the second flow path member 42.

[0139] [Second embodiment] Next, a head system HS2 according to a second embodiment of the present invention will be described with reference to FIGS.

[0140] The head system HS2 of the second embodiment is configured to allow two different types of ink (black ink and yellow ink, as an example) to circulate through one head unit 100. Specifically, the head system HS2 of the second embodiment uses a flow path member 70 (FIGS. 12 and 13) instead of the ink supply pipe 20, the ink discharge pipe 30, the first block flow path 41, and the second block flow path 42 of the first embodiment.

[0141] Furthermore, the printing apparatus 1000 used with the head system HS2 of the second embodiment is provided with first and second sub-tanks (fill tanks) ST1 and ST2 instead of the sub-tank (fill tank) ST, and first and second drain tanks DT1 and DT2 instead of the drain tank DT (FIG. 14). A pump PP1 is provided between the first sub-tank ST1 and the first drain tank DT1, and a pump PP2 is provided between the second sub-tank ST2 and the first drain tank DT2. The ink supply system ISS2 of the second embodiment is configured by the head system HS2, the first and second sub-tanks ST1 and ST2, the first and second drain tanks DT1 and DT2, and the first and second pumps PP1 and PP2 connected thereto.

[0142] The other configuration is the same as that of the head system HS1 of the first embodiment, so a description thereof will be omitted.

[0143] As shown in Figures 12 and 13, the flow path member 70 has a first flow path block (first flow path forming member) 71, a second flow path block (second flow path forming member) 72, and a rubber sheet (elastic sheet) 73 interposed between them.

[0144] The first flow path block 71 is formed, for example, from a resin such as POM, and has a rectangular plate-shaped main part MP, a first base part BP1 protruding to the feed side and downward from the left corner of the main part MP in the medium width direction and the lower side, and a second base part BP2 protruding to the feed side and downward from the right corner of the main part MP in the medium width direction and the lower side.

[0145] Ink circulation ports CP1 and CP2 are formed side by side in the medium width direction on the upper surface MPu of the main part MP. The ink circulation port CP1 is located on the left side of the center of the main part MP in the medium width direction, and the ink circulation port CP2 is located on the right side of the center of the main part MP in the medium width direction.

[0146] Ink circulation ports CP3 and CP4 are formed on the underside of the base portion BP1, side by side in the medium feed direction. Ink circulation port CP3 is located on the feed side, and ink circulation port CP4 is located on the discharge side. Ink circulation ports CP5 and CP6 are formed on the underside of the base portion BP2, side by side in the medium feed direction. Ink circulation port CP6 is located on the feed side, and ink circulation port CP5 is located on the discharge side.

[0147] A first groove GG1 and a second groove GG2 are formed on an inner surface MPi of the main portion MP (the surface facing the discharge side in the medium feed direction).

[0148] The first groove GG1 is generally inverted V-shaped, and the top GG1 tp Extending downward and to the left in the media width direction from the lower end GG1 bt1 The first part GG11 leading to the top GG1 tp GG1 bt2 and a second portion GG12 leading to

[0149] Top GG1 tp The lower end GG1 is located to the left of the center of the inner surface MPi in the medium width direction. bt1 is located near the left end of the inner surface MPi, and the lower end GG1 bt2 is located near the right end of the inner surface MPi. bt1 is located within the area where the first base portion BP1 is provided, and the lower end portion GG1 bt2 is located within the area in which the second base portion BP2 is provided. tp However, since it is located to the left of the center in the medium width direction of the inner surface MPi, the flow path length of the first portion GG11 is shorter than the flow path length of the second portion GG12.

[0150] The extending direction of the first portion GG11 and the second portion GG12 is inclined at a predetermined angle with respect to the up-down direction (vertical direction). tp From bottom end GG1 bt1 The second portion GG12 is bent twice on the path leading to the top GG1, and the angle of inclination with respect to the vertical direction changes each time the second portion GG12 is bent. tp From bottom end GG1 bt2 The flow path is bent twice on the path leading to the ink passage, and the angle of inclination with respect to the vertical direction changes with each bend. In this way, when the flow path is extended in a direction other than the vertical direction, by inclining the extension direction of the flow path with respect to the horizontal direction, it is possible to suppress the settling of the pigment on the bottom surface of the flow path, and in turn to prevent blockage of the flow path that may occur when the pigment that has settled on the bottom surface of the flow path flows all at once. In addition, air bubbles mixed in the ink are suppressed from remaining on the upper surface of the flow path, and can be more reliably flowed upward. The top GG1 of the first portion GG11 and the second portion GG12 tp The angle of inclination with respect to the vertical axis extending downward from the flow path can be set to any angle equal to or less than 90°. The flow path length can be adjusted by changing the number of bends in the path. By increasing the number of bends, the flow path length can be increased, and by decreasing the number of bends, the flow path length can be decreased.

[0151] The second groove GG2 is formed above the first groove GG1. The second groove GG2 is substantially inverted V-shaped, and the top GG2 tp Extending downward and to the left in the media width direction from the lower end GG2 bt1 A first portion GG21 leading to the top GG2 tp Extending downward and to the right in the medium width direction, the lower end GG2 bt2 and a second portion GG22 leading to

[0152] Top GG2 tp The lower end GG2 is located to the right of the center of the inner surface MPi in the medium width direction. bt1 is located near the left end of the inner surface MPi, and the lower end GG2 bt2 is located near the right end of the inner surface MPi.bt1 is located within the area where the first base portion BP1 is provided, and the lower end portion GG2 bt2 is located within the area in which the second base portion BP2 is provided. tp However, since it is located to the right of the center in the medium width direction of the inner surface MPi, the flow path length of the second portion GG22 is shorter than the flow path length of the first portion GG21.

[0153] Inside the main portion MP, a top portion GG1 is tp ,GG2 tp The lower end of the flow passage cch1 is aligned with the top GG1 of the first groove GG1. tp The upper end of the flow passage cch1 communicates with the ink flow port CP1 on the upper surface MPu of the main portion MP. The lower end of the flow passage cch2 communicates with the top GG2 of the second groove GG2. tp The flow passage cch2 communicates with the second groove GG2 via an opening AA2 formed in the upper end thereof, and the upper end of the flow passage cch2 communicates with an ink flow port CP2 in the upper surface MPu of the main portion MP.

[0154] The inside of the main part MP and the base part BP1 has a lower end GG1 of the first groove GG1. bt1 A flow path cch3 connecting the ink flow hole CP3 on the lower surface of the base portion BP1 and the lower end portion GG2 of the second groove GG2 bt1 and a flow passage cch4 that connects the ink flow passage CP4 on the lower surface of the base portion BP1 to the ink flow passage CP4 on the lower surface of the base portion BP1.

[0155] The upper end of the flow passage cch3 is the lower end GG1 of the first groove GG1. bt1 The flow passage cch3 communicates with the first groove GG1 through an opening AA3 formed in the second groove GG2. The flow passage cch3 extends from the upper end to the feed side in the medium feed direction, and then bends downward and extends to the ink circulation hole CP3. The upper end of the flow passage cch4 is connected to the lower end GG2 of the second groove GG2. bt1The flow passage cch4 communicates with the second groove GG2 through an opening AA4 formed in the upper end of the flow passage cch4. The flow passage cch4 extends from the upper end toward the feed side in the medium feed direction, then bends downward, passes beside the flow passage cch3, and extends to the ink circulation hole CP4. As shown in Fig. 13, the flow passage length of the region extending horizontally toward the feed side in the medium feed direction is longer in the flow passage cch3 than in the flow passage cch4.

[0156] The inside of the main part MP and the base part BP2 has a lower end GG1 of the first groove GG1. bt2 and a flow passage cch5 connecting the ink flow hole CP5 on the lower surface of the base portion BP2 and the lower end portion GG2 of the second groove GG2. bt2 and an ink flow passage cch6 that connects the ink flow passage CP6 on the lower surface of the base portion BP2 to the ink flow passage CP6 on the lower surface of the base portion BP2.

[0157] The upper end of the flow passage cch5 is the lower end GG1 of the first groove GG1. bt2 The flow passage cch5 communicates with the first groove GG1 through an opening AA5 formed in the second groove GG2. The flow passage cch5 extends from the upper end to the feed side in the medium feed direction, and then bends downward and extends to the ink circulation hole CP5. The upper end of the flow passage cch6 is connected to the lower end GG2 of the second groove GG2. bt2 The flow passage cch6 communicates with the second groove GG2 via an opening AA6 formed in the upper end of the flow passage cch6. The flow passage cch6 extends from the upper end toward the feed side in the medium feed direction, and then bends downward and extends to the ink circulation hole CP6. As shown in FIG. 13, the flow passage length of the region extending horizontally toward the feed side in the medium feed direction is longer in the flow passage cch6 than in the flow passage cch5. Furthermore, the flow passage lengths of the region extending horizontally toward the feed side in the medium feed direction are equal in the flow passages cch3 and cch6, and are equal in the flow passages cch4 and cch5.

[0158] In the first flow path block 71 of the second embodiment, the flow path length of the first groove GG1 and the flow paths cch3, cch5 are set so that the flow path length between the ink circulation port CP1 and the ink circulation port CP3 is equal to the flow path length between the ink circulation port CP1 and the ink circulation port CP5. In other words, the difference in flow path length between the flow paths cch3 and cch5 caused by the position of the ink circulation port CP3 being misaligned with the position of the ink circulation port CP5 in the medium feed direction is compensated for by the apex GG1 of the first groove GG1. tp is positioned on the left side in the medium width direction to make the flow path length of the first portion GG11 shorter than the flow path length of the second portion GG12, thereby offsetting the difference.

[0159] In the first flow path block 71 of the second embodiment, the flow path lengths of the first portion GG21 and the second portion GG22 of the second groove GG2 and the flow paths cch4 and cch6 are set so that the flow path length between the ink circulation port CP2 and the ink circulation port CP4 is equal to the flow path length between the ink circulation port CP2 and the ink circulation port CP6.

[0160] The second flow path block 72 has a structure that is mirror-symmetrical with respect to the plane extending in the up-down direction and the medium width direction to the first flow path block 71. In the following description, the parts of the second flow path block 72 that are located in mirror-symmetrical positions with respect to the parts of the first flow path block 71 will be referred to by the same reference numerals as the parts of the first flow path block 71.

[0161] The rubber sheet 73 is, for example, an EPDM or silicone sheet. When viewed in the medium feeding direction, the rubber sheet 73 has approximately the same shape as the first and second flow path blocks 71, 72. The thickness of the rubber sheet 73 can be, for example, about 0.1 to 0.5 mm.

[0162] The first flow path block 71 and the second flow path block 72 are opposed to each other by the inner surface MPi of each main portion MP. In this state, the two are joined together with a rubber sheet 73 sandwiched therebetween.

[0163] By covering the first groove GG1 and the second groove GG2 of the first and second flow path blocks 71 and 72 with the rubber sheet 73, a branch flow path constituted by the flow paths cch1, cch3, cch5 and the first groove GG1, and a branch flow path constituted by the flow paths cch2, cch4, cch6 and the second groove GG2 are formed inside the first and second flow path blocks 71 and 72, respectively. Since the first and second grooves GG1 and GG2 are covered with the rubber sheet 73 to form the flow paths, the cross-sectional shape of the flow path is variable within the flow paths, and fluctuations in hydraulic pressure caused by changes in flow rate are suppressed.

[0164] In a state where the first flow path block 71 and the second flow path block 72 are joined together, the ink circulation ports CP3, CP4 of the first flow path block 71 and the ink circulation ports CP3, CP4 of the second flow path block 72 are aligned in the medium feed direction at the left end in the medium width direction. Similarly, the ink circulation ports CP5, CP6 of the first flow path block 71 and the ink circulation ports CP5, CP6 of the second flow path block 72 are aligned in the medium feed direction at the right end in the medium width direction.

[0165] 12, the flow path member 70 is connected to the upper surface of the frame member 50. In this state, the eight ink circulation ports CP3 to CP6 of the flow path member 70 communicate with the eight flow path through holes th of the frame member 50, respectively.

[0166] <Flow path configuration of head system HS2> The flow paths formed by the head system HS2 having the above configuration will be summarized with reference to Fig. 14. Here, it is assumed that the first sub-tank ST1 contains black ink, and the second sub-tank ST2 contains yellow ink.

[0167] A first supply flow path S1 for sending black ink from the first sub-tank ST1 to the head 60, and a first discharge flow path D1 for sending black ink from the head 60 to the drain tank DT1 are formed by a first flow path block 71 of the flow path member 70 and a flow path through hole th of the frame member 50.

[0168] Ink is supplied from the first sub-tank ST1 to the ink flow port (first supply port) CP1 of the first flow path block 71 via the ink flow path member IC2, and reaches the first groove GG1 through the flow path cch1. tp In this case, it is divided into two.

[0169] One of the two separated ink flows through the first portion GG11 of the first groove GG1, the flow passage cch3, the ink flow port CP3, the flow passage through hole th of the frame member 50, and the ink flow port CP4 of the head 60 on the left side in the medium width direction and on the most feeding side in the medium feed direction. 61 The other of the two split ink flows through the second portion GG12 of the first groove GG1, the flow passage cch5, the ink circulation port CP5, the flow passage through hole th of the frame member 50, and the ink circulation port CP2 that is the second ink circulation port CP3 from the right side in the medium width direction and the feed side end in the medium feed direction of the head 60. 61 Then, it flows into manifold M3.

[0170] Through the manifold M4, the ink flow port CP is located on the right side in the media width direction and on the most feeding side in the media feed direction. 61 The ink flows through the ink flow port CP6 of the first flow path block 71, the flow path cch6, the second portion GG22 of the second groove GG2, and reaches the top GG2 of the second groove GG2. tp Through the manifold M3, the ink flow port CP 61 The ink flows through the ink flow port CP4 of the first flow path block 71, the flow path cch4, the first portion GG21 of the second groove GG2, and reaches the top GG2 of the second groove GG2. tp These inks are tp The ink flows through the flow path cch2, the ink circulation port (first discharge port) CP2, and the ink flow path member IC3 to the drain tank DT1. The ink in the first drain tank DT1 is sent to the first sub-tank ST1 by the first pump PP1.

[0171] A second supply flow path S2 for sending yellow ink from the second sub-tank ST2 to the head 60, and a second discharge flow path D2 for sending yellow ink from the head 60 to the second drain tank DT2 are formed by the second flow path block 72 of the flow path member 70 and the flow path through hole th of the frame member 50.

[0172] The ink supplied from the second sub-tank ST2 to the ink flow port CP2 (second supply port) of the second flow path block 72 through the ink flow path member IC2 reaches the second groove GG2 through the flow path cch2 and reaches the top GG2 of the second groove GG2. tp In this case, it is divided into two.

[0173] One of the two separated ink flows through the first portion GG21 of the second groove GG2, the flow path cch4, the ink flow port CP4, the flow path through hole th of the frame member 50, and the third ink flow port CP1 of the head 60 from the left side in the medium width direction and the feed side end in the medium feed direction. 61 The other of the two split ink flows through the second portion GG22 of the second groove GG2, the flow passage cch6, the ink circulation port CP6, the flow passage through hole th of the frame member 50, and the fourth ink circulation port CP 61 Then, it flows into the manifold M1.

[0174] Through the manifold M2, the third ink flow port CP 61 The ink flows through the ink flow port CP5 of the second flow path block 72, the flow path cch5, the second portion GG12 of the first groove GG1, and reaches the top GG1 of the first groove GG1. tp The ink flow port CP 1 passes through the manifold M1 and is the fourth ink flow port CP 61 The ink flows through the ink flow port CP3 of the second flow path block 72, the flow path cch3, the first portion GG11 of the first groove GG1, and reaches the top GG1 of the first groove GG1. tp These inks are tpThe ink flows through the ink passage cch1, the ink flow port CP1 (second outlet port) and the ink passage member IC3 to the drain tank DT2. The ink in the second drain tank DT2 is sent to the second sub-tank ST2 by the second pump PP2.

[0175] Here, in the first supply flow path S1, the ink flow port CP1 (first supply port) of the first flow path block 71 and the top GG1 of the first groove GG1 tp The flow path formed between the top GG1 and the bottom GG2 is a common supply flow path (first common supply flow path) S10. tp 3 to the manifolds M4 and M3 are supply branch channels (first supply branch channels) S11.

[0176] The first flow path block 71 and the frame member 50 may be configured so that the flow path resistances of the two supply tributary flow paths S11 are the same. Specifically, for example, the first flow path block 71 may be configured so that the flow path lengths of the two supply tributary flow paths S11 are the same, and the cross-sectional areas (cross-sectional areas in a plane perpendicular to the direction in which the flow paths extend) of the two supply tributary flow paths S11 are the same. This allows the top GG1 of the first groove GG1 to be tp The amount of ink sent from the manifold M3 to each of the two supply branch paths S11 is equal (equal amount branching is possible), allowing the ink to flow at a stable flow rate. In addition, the flow rate of the ink flowing through the manifold M3 and the flow rate of the ink flowing through the manifold M4 are the same, which makes it possible to more effectively eliminate temperature unevenness of the ink flowing through the manifolds M3 and M4, and thus to more effectively eliminate density unevenness in image formation.

[0177] The first flow path block 71 may be configured so that the flow path length of a region (inclined portion) of the first groove GG1 that extends in a direction intersecting a plane (horizontal plane) including the medium width direction and the medium feed direction and in a direction different from the vertical direction is more than half the flow path length of the first supply flow path S1.

[0178] In the first discharge flow path D1, the ink flow port CP2 (first discharge port) of the first flow path block 71 and the top GG2 of the second groove GG2 tpThe flow path formed between the top GG2 and the bottom GG3 is a common exhaust flow path (first common exhaust flow path) D10. tp 3 to the manifolds M4 and M3 are exhaust tributary paths (first exhaust tributary paths) D11.

[0179] The first flow path block 71 and the frame member 50 may be configured so that the flow path resistances of the two discharge tributary paths D11 are the same. Specifically, for example, the first flow path block 71 may be configured so that the flow path lengths of the two discharge tributary paths D11 are the same, and the cross-sectional areas (cross-sectional areas in a plane perpendicular to the direction in which the flow paths extend) of the two discharge tributary paths D11 are the same. As a result, the top GG2 of the second groove GG2 tp The amount of ink sent from each of the two discharge branch paths D11 toward the manifold M1 is equal (equal amount branching is possible), allowing the ink to flow at a stable flow rate. In addition, the flow rate of the ink flowing through the manifold M3 and the flow rate of the ink flowing through the manifold M4 are the same, which makes it possible to more effectively eliminate temperature unevenness of the ink flowing through the manifolds M3 and M4, and thus to more effectively eliminate density unevenness in image formation.

[0180] The first flow path block 71 may be configured so that the flow path length of a region (inclined portion) of the second groove GG2 extending in a direction intersecting a plane (horizontal plane) including the medium width direction and the medium feed direction and different from the vertical direction is more than half the flow path length of the first discharge flow path D1.

[0181] In the second supply flow path S2, the ink flow port CP2 (second supply port) of the second flow path block 72 and the top GG2 of the second groove GG2 tp The flow path formed between the top GG2 is a common supply flow path (second common supply flow path) S20. tp 3 to the manifolds M2 and M1 are supply branch channels (second supply branch channels) S21.

[0182] In the second discharge flow path D2, the ink flow port CP1 (second discharge port) of the second flow path block 72 and the top GG1 of the first groove GG1 tpThe flow path formed between the top GG1 and the bottom GG20 is a common exhaust flow path (second common exhaust flow path) D20. tp 3 to the manifolds M2 and M1 are discharge tributary channels (second discharge tributary channels) D21.

[0183] The first flow path block 71 and the second flow path block 72 may be configured so that the flow path resistance of the first supply flow path S1 is the same as the flow path resistance of the second supply flow path S2, and may be configured so that the flow path resistance of the first discharge flow path D1 is the same as the flow path resistance of the second discharge flow path D2. This makes it possible to regard the two ink flow paths independent of each other as flow paths of substantially the same quality, making it difficult for a difference in flow rate to occur between the two flow paths, and thus making it possible to more suitably suppress deterioration in image quality.

[0184] In this embodiment, for example, if the error of the flow resistance of one of the two supply tributaries S11 relative to the flow resistance of the other of the two supply tributaries S11 is within 10% of the flow resistance of the other of the two supply tributaries S11, equal branching can be realized and density unevenness in image formation can be suppressed favorably. Similarly, if the error of the flow resistance of one of the two discharge tributaries D11 relative to the flow resistance of the other of the two discharge tributaries D11 is within 10% of the flow resistance of the other of the two discharge tributaries D11, equal branching can be realized and density unevenness in image formation can be suppressed favorably. Also, if the error of the flow resistance of the first supply flow path S1 relative to the flow resistance of the second supply flow path S2 is within 10% of the flow resistance of the second supply flow path S2, a difference in flow rate between the two flow paths is unlikely to occur, and deterioration of image quality can be more favorably suppressed.

[0185] As described above with respect to the present specification and the present invention, also in this embodiment and its modified examples, the flow resistance of a certain flow path is the same as the flow resistance of another flow path means that the error of the flow resistance of a certain flow path relative to the flow resistance of the other flow path is within 10% of the flow resistance of the other flow path. The cross-sectional area of ​​a certain flow path is the same as the cross-sectional area of ​​another flow path means that the error of the cross-sectional area of ​​a certain flow path relative to the cross-sectional area of ​​the other flow path is less than 10% of the cross-sectional area of ​​the other flow path. The flow length of a certain flow path is the same as the flow length of another flow path means that the error of the flow length of a certain flow path relative to the flow length of the other flow path is less than 10% of the flow length of the other flow path. Note that when comparing the cross-sectional area of ​​a certain flow path with the cross-sectional area of ​​another flow path, if the cross-sectional area is not constant throughout the flow path, the average value of the cross-sectional areas throughout the flow path may be used. In addition, the flow velocity of a liquid flowing through a certain flow path being the same as the flow velocity of a liquid flowing through another flow path means that the error in the flow velocity of the liquid flowing through one flow path relative to the flow velocity of the liquid flowing through the other flow path is within 10% of the flow velocity of the liquid flowing through the other flow path.

[0186] The directions in which ink flows in the first and second supply flow paths S1, S2, the manifolds M1 to M4, and the first and second discharge flow paths D1, D2 are as shown by the arrows in Fig. 14. As shown in Fig. 14, in the head system HS2 of this embodiment, the ink flows toward the left in the medium width direction in the manifolds M1 and M3, and the ink flows toward the right in the medium width direction in the manifolds M2 and M4. This suppresses degradation of image quality by a mechanism similar to that of the head system HS1 of the first embodiment.

[0187] The effects of the head system HS2 of the second embodiment are summarized below.

[0188] The supply flow paths S1 and S2 and the discharge flow paths D1 and D2 of the head system HS2 of the second embodiment are as follows: The head 60 is configured to supply and discharge ink to and from manifolds arranged adjacent to each other in the medium feed direction so that the ink flows in opposite directions. Therefore, density unevenness that may occur in an image formed by the nozzle rows L3 corresponding to each manifold can be offset between the manifolds adjacent in the medium feed direction (between the nozzle rows adjacent in the medium feed direction), and deterioration in the quality of the formed image can be suppressed.

[0189] In the head system HS2 of the second embodiment, all of the manifolds M1 to M4 of the head 60 are linear and extend in the medium width direction. Therefore, the flow path length is shorter than that of a manifold that is U-shaped in a plan view and extends from an ink supply port (upstream end) to one side in the medium width direction and then turns back to extend to the ink discharge side (downstream end). Therefore, the difference in temperature between the ink supplied to the pressure chamber connected near the upstream end of the manifold and the ink supplied to the pressure chamber connected near the downstream end of the manifold is small, and deterioration of image quality according to changes in ink temperature is suppressed.

[0190] The head system HS2 of the second embodiment includes supply flow paths S1 and S2 that are separated from each other over the entire area from the ink supply port to the head, and discharge flow paths D1 and D2 that are separated from each other over the entire area from the head to the ink discharge port, so that two different types of ink can be circulated through a single head.

[0191] In the head system HS2 of the second embodiment, most of the supply flow path S1 and the discharge flow path D1 are formed by an integral flow path block 71, and most of the supply flow path S2 and the discharge flow path D2 are formed by an integral flow path block 72. Furthermore, the flow path block 71 and the flow path block 72 are joined together and disposed above the head 60. This allows the flow paths to be efficiently disposed in the limited space on the head 60, and the head system HS2 to be made compact. Furthermore, forming the flow paths from POM or the like increases the durability of the flow paths against ink.

[0192] The ink supply system ISS2, the printing apparatus 1000, and the ink distribution method of the second embodiment also have the same effects as the head system HS2.

[0193] [Variation 2-1] Next, an ink supply system ISS2' according to the modified example 2-1 will be described with reference to FIG.

[0194] In the ink supply system ISS2' of modified example 2-1, similarly to the ink supply system ISS2 of the second embodiment, a second supply flow path S2' for sending yellow ink from the second sub-tank ST2 to the head 60, and a second discharge flow path D2' for sending yellow ink from the head 60 to the second drain tank DT2 are formed by a second flow path block 72 of the flow path member 70 and a flow path through hole th of the frame member 50. However, the direction of ink flow in the second flow path block 72 is opposite to that of the ink supply system ISS2 of the second embodiment.

[0195] As shown in Figure 15, in the ink supply system ISS2' of variant example 2-1, the second sub-tank ST2 and the ink flow port CP1 of the second flow path block 72 are connected by an ink flow path member IC2, and the second drain tank DT2 and the ink flow port CP2 of the second flow path block 72 are connected by an ink flow path member IC3.

[0196] Ink is supplied from the second sub-tank ST2 to the ink flow port CP1 (second supply port) of the second flow path block 72 via the ink flow path member IC2, passes through the flow path cch1, reaches the first groove GG1, and contacts the top GG1 of the first groove GG1. tp In this case, it is divided into two.

[0197] One of the two ink flows through the first portion GG11 of the first groove GG1, the flow path cch3, and the ink circulation port CP3, and then flows into the manifold M1 from the right side in the medium width direction. The other of the two ink flows through the second portion GG12 of the first groove GG1, the flow path cch5, and the ink circulation port CP5, and then flows into the manifold M2 from the right side in the medium width direction.

[0198] The ink that has reached the ink flow port CP6 of the second flow path block 72 through the manifold M1 passes through the second portion GG22 of the second groove GG2 and reaches the top GG2 of the second groove GG2. tp The ink that has reached the ink flow port CP4 of the second flow path block 72 through the manifold M2 passes through the first portion GG21 of the second groove GG2 and reaches the top GG2 of the second groove GG2. tp These inks are tp The two ink flows join at and flow through the flow path cch2, the ink circulation port CP2 (second outlet port), and the ink flow path member IC3 to the drain tank DT2.

[0199] In the second supply flow path S2', the ink flow port CP1 (second supply port) of the second flow path block 72 and the top GG1 of the first groove GG1 tp The flow path formed between the top GG1 and the bottom GG2 is a common supply flow path (second common supply flow path) S20'. tp 3 to the manifolds M2 and M1 are supply branch channels (second supply branch channels) S21'.

[0200] In the second discharge flow path D2', the ink flow port CP2 (second discharge port) of the second flow path block 72 and the top GG2 of the second groove GG2 tp The flow path formed between the top GG2 and the bottom GG2 is a common exhaust flow path (second common exhaust flow path) D20'. tp The flow paths from the manifolds M2 and M1 are exhaust tributary flow paths (second exhaust tributary flow paths) D21'.

[0201] In the ink supply system ISS2' of the modified example 2-1, the ink flows toward the right side in the medium width direction in the manifolds M1 and M4, and the ink flows toward the left side in the medium width direction in the manifolds M2 and M3, as shown in Fig. 15. Density unevenness is offset (averaged) between the manifolds M1 and M2, and between the manifolds M3 and M4, and deterioration in the quality of the formed image is suppressed.

[0202] In the ink supply system ISS2 of the second embodiment, the first sub-tank ST1 and the ink flow port CP2 of the first flow path block 71 may be connected by an ink flow path member IC2, and the first drain tank DT1 and the ink flow port CP1 of the first flow path block 71 may be connected by an ink flow path member IC3. In this case, ink flows toward the left in the medium width direction in the manifolds M1 and M4, and ink flows toward the right in the medium width direction in the manifolds M2 and M3.

[0203] [Variation 2-2] Next, an ink supply system ISS2″ according to the modified example 2-2 will be described with reference to FIGS.

[0204] In the ink supply system ISS2" of the modified example 2-2, a flow path block 70" is used instead of the flow path block 70 provided in the ink supply system ISS2 of the second embodiment. Since other points are the same as those of the ink supply system ISS2 of the second embodiment, the description will be omitted.

[0205] The flow path block 70 ″ differs from the flow path block 70 of the second embodiment in that a first flow path block 71 ″ is provided instead of the first flow path block 71 .

[0206] In the first flow path block 71'', the configuration of the flow paths cch3 to cch6 is different from the configuration of the flow paths cch3 to cch6 of the first flow path block 71.

[0207] Specifically, the upper end of the flow passage cch3 is aligned with the lower end GG1 of the first groove GG1. bt1 The flow passage cch3 communicates with the first groove GG1 through an opening AA3 formed in the second groove GG2. The flow passage cch3 extends from the upper end to the feed side in the medium feed direction, and then bends downward and extends to the ink circulation hole CP4. The upper end of the flow passage cch4 is connected to the lower end GG2 of the second groove GG2. bt1The flow passage cch4 communicates with the second groove GG2 through an opening AA4 formed in the upper end of the flow passage cch4. The flow passage cch4 extends from the upper end toward the feed side in the medium feed direction, then bends downward and extends to the ink circulation hole CP3. As shown in Fig. 16, the flow passage length of the region extending horizontally toward the feed side in the medium feed direction is longer in the flow passage cch4 than in the flow passage cch3.

[0208] The upper end of the flow passage cch5 is the lower end GG1 of the first groove GG1. bt2 The flow passage cch5 communicates with the first groove GG1 through an opening AA5 formed in the second groove GG2. The flow passage cch5 extends from the upper end to the feed side in the medium feed direction, and then bends downward and extends to the ink circulation hole CP6. The upper end of the flow passage cch6 is connected to the lower end GG2 of the second groove GG2. bt2 The flow passage cch6 communicates with the second groove GG2 through an opening AA6 formed in the flow passage cch6. The flow passage cch6 extends from the upper end toward the feed side in the medium feed direction, then bends downward, and extends to the ink circulation hole CP5 by passing beside the flow passage cch5. As shown in FIG. 16, the flow passage length of the region extending horizontally toward the feed side in the medium feed direction is longer in the flow passage cch5 than in the flow passage cch6. Furthermore, the flow passage lengths of the region extending horizontally toward the feed side in the medium feed direction are equal in the flow passages cch3 and cch6, and are equal in the flow passages cch4 and cch5.

[0209] In the first flow path block 71'', the flow path length between the opening AA1 and the ink circulation port CP4 is shorter than the flow path length between the opening AA1 and the ink circulation port CP6. Therefore, the cross-sectional area of ​​the flow path between the opening AA1 and the ink circulation port CP6 is larger than the cross-sectional area of ​​the flow path between the opening AA1 and the ink circulation port CP4 so that the flow path resistances of both flows are equal to each other. Note that the number of bends of the first groove GG11 and the second groove GG12 may be changed, or the top GG1 may be changed. tp The position of the ink flow passage CP4 may be shifted in the medium width direction, so that the length of the ink flow passage between the opening AA1 and the ink flow passage CP4 and the length of the ink flow passage between the opening AA1 and the ink flow passage CP6 are equal to each other. In this case, the cross-sectional areas of both ink flow passages may be equal to each other.

[0210] Similarly, in the first flow path block 71'', the flow path length of the flow path between the opening AA2 and the ink circulation port CP5 is shorter than the flow path length of the flow path between the opening AA2 and the ink circulation port CP3. Therefore, the cross-sectional area of ​​the flow path between the opening AA2 and the ink circulation port CP3 is larger than the cross-sectional area of ​​the flow path between the opening AA2 and the ink circulation port CP5 so that the flow path resistances of both flows are equal to each other.

[0211] The ink supply system ISS2'' of the modified example 2-2 includes a flow path block 70'' instead of the flow path block 70, and thereby configures supply flow paths S1'', D1'' (FIG. 17) instead of the supply flow path S1 and the discharge flow path D1.

[0212] Specifically, as shown in FIG. 17, ink is supplied from the first sub-tank ST1 to the ink flow port (first supply port) CP1 of the first flow path block 71″ via the ink flow path member IC2, and reaches the first groove GG1 through the flow path cch1. tp In this case, it is divided into two.

[0213] One of the two ink streams passes through the first portion GG11 of the first groove GG1, the flow path cch3, and the ink circulation port CP4, and then flows into the manifold M3 from the left side in the width direction of the medium. The other of the two ink streams passes through the second portion GG12 of the first groove GG1, the flow path cch5, and the ink circulation port CP6, and then flows into the manifold M4 from the right side in the width direction of the medium.

[0214] After flowing rightward through the manifold M3, the ink flows in from the ink flow port CP5 of the first flow path block 71″, passes through the flow path cch6 and the second portion GG22 of the second groove GG2, and reaches the top GG2 of the second groove GG2. tp After flowing leftward through the manifold M4, the ink flows in from the ink flow port CP3 of the first flow path block 71″, passes through the flow path cch4 and the first portion GG21 of the second groove GG2, and reaches the top GG2 of the second groove GG2. tp These inks are tpThe ink flows through the flow path cch2, the ink circulation port (first discharge port) CP2, and the ink flow path member IC3 to the drain tank DT1. The ink in the first drain tank DT1 is sent to the first sub-tank ST1 by the first pump PP1.

[0215] Here, in the first supply flow passage S1″, the ink flow port CP1 (first supply port) of the first flow passage block 71″ and the top GG1 of the first groove GG1 tp The flow path formed between the top GG1 and the bottom GG2 is a common supply flow path (first common supply flow path) S10″. tp The flow paths from the first discharge flow path D1″ to the manifolds M4 and M3 are supply branch flow paths (first supply branch flow paths) S11″. In the first discharge flow path D1″, the ink flow port CP2 (first discharge port) of the first flow path block 71″ and the top GG2 of the second groove GG2 tp The flow path formed between the top GG2 is a common exhaust flow path (first common exhaust flow path) D10″. tp The flow paths from the manifolds M4 and M3 are discharge tributary flow paths (first discharge tributary flow paths) D11''.

[0216] In the ink supply system ISS2" of variant example 2-2, as shown in FIG. 17, in manifolds M1 and M4, ink flows toward the left side in the medium width direction, and in manifolds M2 and M3, ink flows toward the right side in the medium width direction. Density unevenness is offset (averaged) between manifolds M1 and M2, and between manifolds M3 and M4, suppressing deterioration in the quality of the formed image.

[0217] In the ink supply system ISS2 of the second embodiment, the second flow path block 72 of the flow path block 70 may be modified in the same manner as the above-mentioned first flow path block 71'' (i.e., so that the second flow path block 72 is mirror symmetrical to the first flow path block 71'' with respect to a plane perpendicular to the medium feed direction). In this case, in the manifolds M1 and M4, ink flows toward the right in the medium width direction, and in the manifolds M2 and M3, ink flows toward the left in the medium width direction.

[0218] The following modified embodiments can also be used in the head system HS2 of the second embodiment, the head system provided in the ink supply system ISS' of variant 2-1, and the head system provided in the ink supply system ISS" of variant 2-2. Although each of the modified embodiments below is described for the head system HS2 of the second embodiment, similar modifications can be used in the head systems of each variant.

[0219] The head system HS2 of the second embodiment has two supply and discharge flow paths, i.e., supply flow paths S1 and S2 and discharge flow paths D1 and D2, but is not limited to this. The head system HS2 may have only the supply flow path S1 and the discharge flow path D1, or only the supply flow path S2 and the discharge flow path D2. Also, the same ink may be circulated through the supply flow paths S1 and S2 and the discharge flow paths D1 and D2, and they may be used as substantially a single supply and discharge flow path.

[0220] In the head system HS2 of the second embodiment, the supply flow paths S1, S2 and the discharge flow paths D1, D2 are configured by the flow path member 70, but are not limited to this. The supply flow paths S1, S2 and the discharge flow paths D1, D2 may be configured by using a tubular member such as a resin tube.

[0221] In the head system HS2 of the second embodiment, a material other than rubber may be used instead of the rubber sheet 73. Any material that can form a flow path by providing a lid to the first groove GG1 and the second groove GG2 of the first and second flow path blocks 71 and 72 can be used, and a material that further exerts a function (damper function) of suppressing the liquid pressure fluctuation caused by the flow rate change by deformation is more preferable. It is preferable to form the sheet with a material that is more flexible than the material forming the first flow path block 71 and the second flow path block 72, but this is not limited. The first and second grooves GG1 and GG2 can be covered and the flow path can be formed by using a material such as resin or metal that has a smaller deflection than rubber.

[0222] The above describes the embodiment and modified examples using as an example a case where ink is ejected from the head systems HS1 and HS2 to form an image on a medium PM. The head systems HS1 and HS2 may be liquid ejection systems that eject any liquid for forming an image, and the medium PM on which the image is formed may be, for example, paper, cloth, resin, etc. The head systems HS1 and HS2 may also be used as head systems in a serial head type printer.

[0223] Furthermore, in the head systems HS1, HS2 and the modified examples, at least one of the manifolds M1 to M4 may branch in the medium feed direction in at least a part of the region between both ends, like the manifold M shown in FIG.

[0224] The manifold M shown in Fig. 18 branches into three small manifolds Ma, Mb, Mc spaced apart in the medium feed direction between the left end and the right end in the medium width direction. The small manifolds Ma, Mb, Mc are parallel to one another. A plurality of individual flow paths (not shown) aligned in the medium width direction are connected to each of the small manifolds Ma, Mb, Mc. Each of the plurality of individual flow paths forms a nozzle row. The small manifolds Ma to Mc essentially behave as a single manifold in suppressing degradation of image quality based on the mechanism of the present invention.

[0225] The embodiments described in this specification are illustrative in all respects and should not be considered as limiting. For example, the number and configuration of the head units 100 may be changed. The number of colors that the printing device 1000 can print simultaneously is not limited, and the printing device 1000 may be configured to be capable of only monochromatic printing. The number and arrangement of the individual flow channels ICH may also be changed as appropriate. The technical features described in each embodiment may be combined with each other.

[0226] As long as the characteristics of the present invention are maintained, the present invention is not limited to the above-described embodiments, and other forms conceivable within the scope of the technical idea of ​​the present invention are also included within the scope of the present invention. [Industrial Applicability]

[0227] According to the head system of the present invention, it is possible to suppress deterioration of image quality caused by changes in ink temperature. [Explanation of symbols]

[0228] 1. Pressure chamber 3 Nozzles 20 Ink supply pipe 30 Ink discharge pipe 41, 71 First flow path block 42, 72 Second flow path block 50 Frame members 60 Head 70 Flow path components 100 Head Unit 700 Platen 801, 802 Conveyor roller 1000 printing devices

Claims

1. Head and a first supply flow path having a first supply port through which a liquid is supplied and extending between the first supply port and the head; A head system having a first outlet for discharging liquid and a first discharge flow path extending between the first outlet and the head, the head includes a manifold extending in a predetermined direction, and two groups including a plurality of pressure chambers, each of the pressure chambers being connected to a nozzle and the manifold; The two groups are arranged in the order of a first group and a second group along a cross direction that crosses the predetermined direction, one end of the manifold included in each of the two groups is located on one side of the predetermined direction, and the other end of the manifold included in each of the two groups is located on the other side of the predetermined direction, the first supply flow path is connected to the one end of the manifold included in the first group and the other end of the manifold included in the second group; the first discharge flow path is connected to the other end of the manifold included in the first group and the one end of the manifold included in the second group, The first supply flow path has a common supply flow path and two supply branch flow paths, the common supply flow path is connected to the first supply port at an upstream end, one of the two supply branch channels is connected at an upstream end to a downstream end of the common supply channel and is connected at a downstream end to the one end of the manifold included in the first group; the other of the two supply branch channels is connected at an upstream end to the downstream end of the common supply channel and is connected at a downstream end to the other end of the manifold included in the second group; a flow resistance of one of the two supply branch paths is equal to a flow resistance of the other of the two supply branch paths, Each of the two supply tributaries includes a first region and a second region downstream of the first region; In each of the two supply branch channels, an upstream end of the first region and a downstream end of the first region are offset from each other in the predetermined direction, and an upstream end of the second region and a downstream end of the second region are offset from each other in the intersecting direction, A head system in which the flow path length of the first region of one of the two supply tributaries is longer than the flow path length of the first region of the other of the two supply tributaries, and the flow path length of the second region of one of the two supply tributaries is shorter than the flow path length of the second region of the other of the two supply tributaries.

2. a flow path length of one of the two supply branch channels is equal to a flow path length of the other of the two supply branch channels; 2. The head system according to claim 1, wherein a cross-sectional area of ​​one of the two supply tributaries is the same as a cross-sectional area of ​​the other of the two supply tributaries.

3. A head system as described in claim 1 or 2, wherein the first supply flow path includes an inclined region extending in a direction intersecting a plane including the specified direction and the intersecting direction and different from the vertical direction, and the flow path length of the inclined region is more than half the flow path length of the first supply flow path.

4. The first discharge flow path has a common discharge flow path and two discharge branch flow paths, The common discharge flow path is connected to a first discharge port at a downstream end thereof, one of the two discharge branch channels is connected at a downstream end to an upstream end of the common discharge channel and is connected at an upstream end to the other end of the manifold included in the first group; the other of the two discharge branch channels is connected at a downstream end to the upstream end of the common discharge channel and is connected at an upstream end to the one end of the manifold included in the second group; 4. The head system according to claim 1, wherein a flow resistance of one of the two discharge tributary paths is equal to a flow resistance of the other of the two discharge tributary paths.

5. a flow path length of one of the two discharge tributaries is equal to a flow path length of the other of the two discharge tributaries; 5. The head system according to claim 4, wherein a cross-sectional area of ​​one of the two exhaust tributaries is the same as a cross-sectional area of ​​the other of the two exhaust tributaries.

6. Each of the two exhaust tributaries includes a first region and a second region upstream of the first region; In each of the two exhaust tributary channels, an upstream end of the first region and a downstream end of the first region are offset from each other in the predetermined direction, and an upstream end of the second region and a downstream end of the second region are offset from each other in the intersecting direction, A head system as described in claim 4 or 5, wherein the flow path length of the first region of one of the two exhaust tributaries is longer than the flow path length of the first region of the other of the two exhaust tributaries, and the flow path length of the second region of one of the two exhaust tributaries is shorter than the flow path length of the second region of the other of the two exhaust tributaries.

7. A head, a first supply flow path having a first supply port through which a liquid is supplied and extending between the first supply port and the head; A head system having a first outlet for discharging liquid and a first discharge flow path extending between the first outlet and the head, the head includes a manifold extending in a predetermined direction, and two groups including a plurality of pressure chambers, each of the pressure chambers being connected to a nozzle and the manifold; The two groups are arranged in the order of a first group and a second group along a cross direction that crosses the predetermined direction, one end of the manifold included in each of the two groups is located on one side of the predetermined direction, and the other end of the manifold included in each of the two groups is located on the other side of the predetermined direction, the first supply flow path is connected to the one end of the manifold included in the first group and the other end of the manifold included in the second group; the first discharge flow path is connected to the other end of the manifold included in the first group and the one end of the manifold included in the second group, The first discharge flow path has a common discharge flow path and two discharge branch flow paths, The common discharge flow path is connected to a first discharge port at a downstream end thereof, one of the two discharge branch channels is connected at a downstream end to an upstream end of the common discharge channel and is connected at an upstream end to the other end of the manifold included in the first group; the other of the two discharge branch channels is connected at a downstream end to the upstream end of the common discharge channel and is connected at an upstream end to the one end of the manifold included in the second group; a flow resistance of one of the two discharge tributary paths is equal to a flow resistance of the other of the two discharge tributary paths; Each of the two exhaust tributaries includes a first region and a second region upstream of the first region; In each of the two exhaust tributary channels, an upstream end of the first region and a downstream end of the first region are offset from each other in the predetermined direction, and an upstream end of the second region and a downstream end of the second region are offset from each other in the intersecting direction, A head system in which the flow path length of the first region of one of the two exhaust tributaries is longer than the flow path length of the first region of the other of the two exhaust tributaries, and the flow path length of the second region of one of the two exhaust tributaries is shorter than the flow path length of the second region of the other of the two exhaust tributaries.

8. A flow path length of one of the two discharge tributaries is the same as a flow path length of the other of the two discharge tributaries; 8. The head system according to claim 7, wherein a cross-sectional area of ​​one of the two exhaust tributaries is the same as a cross-sectional area of ​​the other of the two exhaust tributaries.

9. A head system described in any one of claims 4 to 8, wherein the first discharge flow path includes an inclined region extending in a direction intersecting a plane including the specified direction and the intersecting direction and different from the vertical direction, and the flow path length of the inclined region is at least half the flow path length of the first discharge flow path.

10. A flow path forming member having a groove formed on a surface thereof; an elastic member formed of a material softer than a material forming the flow path forming member, 10. The head system according to claim 1, wherein the first supply flow path is formed by the groove and the elastic member.

11. 11. The head system according to claim 10, wherein the first discharge flow path is formed by the groove and the elastic member.

12. a flow path block formed with the first supply flow path and the first discharge flow path, 10. The head system according to claim 1, wherein the first supply port and the first discharge port are formed on a surface of the flow path block.

13. A head system according to any one of claims 1 to 12, wherein in each of the first group and the second group, the plurality of pressure chambers included in a predetermined group are supplied with liquid only through the manifold included in that predetermined group.

14. 14. The head system according to claim 1, wherein the manifold included in the first group and the manifold included in the second group are provided at the same position relative to each other in the up-down direction.

15. a second supply flow path having a second supply port through which a liquid is supplied and extending between the second supply port and the head; a second discharge flow path having a second discharge port for discharging liquid and extending between the second discharge port and the head; the head has a manifold extending along the predetermined direction, and four groups including the first group and the second group, the groups including a plurality of pressure chambers, each of the pressure chambers being connected to a nozzle and the manifold; The four groups are arranged in the intersecting direction in the order of the first group, the second group, the third group, and the fourth group, one end of the manifold included in each of the four groups is located on one side of the predetermined direction, and the other end of the manifold included in each of the four groups is located on the other side of the predetermined direction, the second supply flow path is connected to the one end of the manifold included in the third group and the other end of the manifold included in the fourth group, A head system described in any one of claims 1 to 14, wherein the second discharge flow path is connected to the other end of the manifold included in the third group and to the one end of the manifold included in the fourth group.

16. A head, a first supply flow path having a first supply port through which a liquid is supplied and extending between the first supply port and the head; a first discharge flow path having a first discharge port for discharging a liquid and extending between the first discharge port and the head; a second supply flow path having a second supply port through which a liquid is supplied and extending between the second supply port and the head; A head system having a second outlet for discharging liquid and a second discharge flow path extending between the second outlet and the head, the head includes a manifold extending in a predetermined direction, and four groups including a plurality of pressure chambers, each of the pressure chambers being connected to a nozzle and the manifold; the four groups are arranged in the order of a first group, a second group, a third group, and a fourth group along a cross direction that crosses the predetermined direction, one end of the manifold included in each of the four groups is located on one side of the predetermined direction, and the other end of the manifold included in each of the four groups is located on the other side of the predetermined direction, the first supply flow path is connected to the one end of the manifold included in the first group and the other end of the manifold included in the second group; the first discharge flow path is connected to the other end of the manifold included in the first group and the one end of the manifold included in the second group, the second supply flow path is connected to the one end of the manifold included in the third group and the other end of the manifold included in the fourth group, A head system, wherein the second discharge flow path is connected to the other end of the manifold included in the third group and to the one end of the manifold included in the fourth group.

17. a second supply flow path having a second supply port through which a liquid is supplied and extending between the second supply port and the head; a second discharge flow path having a second discharge port for discharging liquid and extending between the second discharge port and the head; the head has a manifold extending along the predetermined direction, and four groups including the first group and the second group, the groups including a plurality of pressure chambers, each of the pressure chambers being connected to a nozzle and the manifold; The four groups are arranged in the intersecting direction in the order of the first group, the second group, the third group, and the fourth group, one end of the manifold included in each of the four groups is located on one side of the predetermined direction, and the other end of the manifold included in each of the four groups is located on the other side of the predetermined direction, the second supply flow path is connected to the one end of the manifold included in the fourth group and the other end of the manifold included in the third group, A head system described in any one of claims 1 to 14, wherein the second discharge flow path is connected to the other end of the manifold included in the fourth group and to the one end of the manifold included in the third group.

18. A head, a first supply flow path having a first supply port through which a liquid is supplied and extending between the first supply port and the head; a first discharge flow path having a first discharge port for discharging a liquid and extending between the first discharge port and the head; a second supply flow path having a second supply port through which a liquid is supplied and extending between the second supply port and the head; A head system having a second outlet for discharging liquid and a second discharge flow path extending between the second outlet and the head, the head includes a manifold extending in a predetermined direction, and four groups including a plurality of pressure chambers, each of the pressure chambers being connected to a nozzle and the manifold; the four groups are arranged in the order of a first group, a second group, a third group, and a fourth group along a cross direction that crosses the predetermined direction, one end of the manifold included in each of the four groups is located on one side of the predetermined direction, and the other end of the manifold included in each of the four groups is located on the other side of the predetermined direction, the first supply flow path is connected to the one end of the manifold included in the first group and the other end of the manifold included in the second group; the first discharge flow path is connected to the other end of the manifold included in the first group and the one end of the manifold included in the second group, the second supply flow path is connected to the one end of the manifold included in the fourth group and the other end of the manifold included in the third group, A head system, wherein the second discharge flow path is connected to the other end of the manifold included in the fourth group and the one end of the manifold included in the third group.

19. A head system described in any one of claims 15 to 18, wherein the flow resistance of the first supply flow path is the same as the flow resistance of the second supply flow path, and the flow resistance of the first discharge flow path is the same as the flow resistance of the second discharge flow path.

20. A first flow path forming member having a groove formed on a surface thereof; A second flow path forming member having a groove formed on a surface thereof; an elastic sheet formed of a material softer than a material forming the first flow path forming member and the second flow path forming member, the elastic sheet is sandwiched between the first flow path forming member and the second flow path forming member, A head system according to any one of claims 15 to 19, wherein the first supply flow path and the first discharge flow path are formed by the groove of the first flow path forming member and one surface of the elastic sheet, and the second supply flow path and the second discharge flow path are formed by the groove of the second flow path forming member and the other surface of the elastic sheet.

21. The head system according to claim 20, wherein the groove of the first flow path forming member and the groove of the second flow path forming member are formed so as to be mirror symmetrical with respect to the elastic sheet when the first flow path forming member and the second flow path forming member are in a state in which the elastic sheet is sandwiched between them.

22. A head system described in any one of claims 1 to 21, wherein the number of manifolds through which the liquid flows from the one end to the other end is equal to the number of manifolds through which the liquid flows from the other end to the one end.

23. A head system described in any one of claims 1 to 22, wherein the manifold included in at least one of the first group and the second group branches into a plurality of flow paths spaced apart in the intersecting direction in at least a portion of the region between the one end and the other end.

24. A head system according to any one of claims 1 to 14, 22 and 23; A first supply tank connected to the first supply flow path; A first discharge tank connected to the first discharge flow path; A liquid supply system comprising a first differential pressure mechanism that generates a differential pressure between the first supply tank and the first discharge tank.

25. A head system according to any one of claims 15 to 21, A first supply tank connected to the first supply flow path; A first discharge tank connected to the first discharge flow path; a first differential pressure mechanism that generates a differential pressure between the first supply tank and the first discharge tank; A second supply tank connected to the second supply flow path; A second discharge tank connected to the second discharge flow path; A liquid supply system comprising a second differential pressure mechanism that generates a pressure difference between the second supply tank and the second discharge tank.

26. A liquid supply system according to claim 24 or 25; A printing device comprising a medium transport unit that transports a medium.

27. ​​A liquid circulation method for circulating liquid within the head of a head system using the head system described in any one of claims 1 to 23.

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