JP7600593B2 - HEAD SYSTEM, LIQUID SUPPLY SYSTEM, PRINTING APPARATUS, AND LIQUID DISTRIBUTING METHOD - Google Patents

Description

The present invention relates to a head system, a liquid supply system, a printing device, and a liquid distribution method.

There are image recording devices that record images by ejecting liquid such as ink onto a medium such as paper through a liquid ejection head. A liquid ejection head generally comprises a number of pressure chambers that contain liquid, a number of nozzles each 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 (see, for example, Patent Document 1). Liquid is ejected from the liquid ejection head by increasing the internal pressure of the desired pressure chamber using the actuator, and pushing ink out of the nozzle connected to the pressure chamber.

JP 2015-36218 A

The inventors of the present invention conducted extensive research into the quality of images formed by existing liquid ejection heads and discovered that a decrease in image quality can occur due to changes in the temperature of the liquid.

The present invention aims to provide a head system, a liquid supply system, a printing device, and a liquid distribution method that can suppress deterioration of image quality caused by temperature changes in the liquid.

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 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;
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.

According to a second 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 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.

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 for generating a pressure differential between the second supply tank and the second discharge tank.

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.

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.

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.

FIG. 1 is a diagram showing a schematic configuration of a printer. FIG. 2 is a plan view showing a schematic configuration of the head unit. FIG. 3 is a perspective view of the head system according to the first embodiment of the present invention. 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. 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. FIG. 6 is an exploded perspective view of the frame member and the head. FIG. 7 is a plan view of the flow passage unit and the actuator. FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. FIG. 9 is an explanatory diagram showing flow paths formed by the ink supply system according to the first embodiment of the present invention. 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. FIG. 11 is an explanatory diagram showing flow paths formed by the ink supply system of the modified example 1-1. FIG. 12 is a perspective view of a head system according to the second embodiment of the present invention. FIG. 13 is an exploded perspective view of the flow path member. FIG. 14 is an explanatory diagram showing flow paths formed by an ink supply system according to a second embodiment of the present invention. FIG. 15 is an explanatory diagram showing flow paths formed by the ink supply system of the modified example 2-1. FIG. 16 is an exploded perspective view of a flow path member according to Modification 2-2. FIG. 17 is an explanatory diagram showing flow paths formed by the ink supply system of the modified example 2-2. FIG. 18 is a plan view showing a modified embodiment of the manifold.

[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.

<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 unit 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.

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. With regard to 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."

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

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

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, these four colors are cyan, magenta, yellow, and black. The specific structure and function of each of the head units 100 will be described later.

The platen 700 is a plate-like member that supports the medium PM from the opposite side (below) to 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 greater than the width of the largest medium on which the printer 1000 can record an image.

The pair of transport rollers 801, 802 are arranged on either side of the platen 700 in the media feed direction. The pair of transport rollers 801, 802 transport the medium PM to the discharge side in the media feed direction in a predetermined manner when the head unit 100 forms an image on the medium PM. The transport rollers 801, 802 are an example of the "media transport section" of the present invention.

The ink tank IT is divided into four sections to accommodate four colors of ink. The sub tank ST and drain tank DT are provided above each head unit 100.

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, i.e., one for each color.

As shown in FIG. 2, each of the four subtanks 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 a 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 subtank ST and the drain tank DT. The ink supply system ISS1 of the first embodiment is composed of the head system HS1, the subtank ST connected thereto, the drain tank DT, and the pump PP.

The control unit CONT controls each part of the printer 1000 as a whole, and performs operations such as forming an image on the medium PM. The control unit CONT is equipped with an FPGA (Field Programmable Gate Array), an EEPROM (Electrically Erasable Programmable Read-Only Memory), a RAM (Random Access Memory), etc. The control unit CONT may also be equipped with a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), etc. The control device CONT is connected to an external device (not shown) such as a PC so that data communication is possible, and controls each part of the printer 1000 based on the print data sent from the external device.

<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.

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

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

<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.

<Ink supply tube 20>
The ink supply pipe 20 forms a part of a supply flow path S (FIG. 9) for flowing ink from the subtank ST to the head 60. The ink supply pipe 20 is a branched pipe having one upstream end 20a, a branch portion 20x, and two downstream ends 20b1, 20b2. The upstream end 20a is disposed above the downstream ends 20b1, 20b2.

The ink supply tube 20 has an ink supply port _SP20 at its upstream end 20a. The ink supply port _SP20 is connected to the downstream end of an ink flow path member IC2, the upstream end of which is connected to the sub-tank ST.

<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.

The ink discharge pipe 30 has an ink discharge port _DP30 at a downstream end 30b. The ink discharge port _DP30 is connected to the upstream end of an ink flow path member IC3, the downstream end of which is connected to a drain tank DT.

<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 on the downstream side of the ink supply pipe 20 and on the upstream side of the ink discharge pipe 30.

The first and second flow path blocks 41 and 42 have the same structure, so only the first flow path block 41 will be described here.

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

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

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

An inverted V-shaped groove G1 is formed on the side MBr of the main body MB on the right side in the medium width direction. The groove G1 includes a first portion G11 that extends downward from the top _G1tp (FIG. 5B) toward the discharge side in the medium feed direction to a lower end _G1bt1 , and a first portion G12 that extends downward from the top _G1tp toward the feed side in the medium feed direction to a lower end _G1bt2 . The top _G1tp is located in an area of the side MBr that is closer to the discharge side than the center in the medium feed direction.

An inverted V-shaped groove G2 is formed on the left side surface MBl 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 includes a first portion G21 that extends from the top G2 _tp downward and toward the discharge side in the medium feed direction to the bottom end G2 _bt1 , and a second portion G22 that extends from the top G2 _tp downward and toward the feed side in the medium feed direction to the bottom end G2 _bt2 . The top G2 _tp is located in an area of the side surface MBl that is closer to the feed side than the center in the medium feed direction. That is, the groove G1 and the groove G2 are formed at positions shifted from each other in the medium feed direction.

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, by making the extension direction of the flow path different from the horizontal direction in this way, it is possible to suppress the precipitation of pigment on the bottom surface of the flow path. In addition, it is possible to suppress the retention of air bubbles mixed in the ink on the upper surface of the flow path, and to more reliably flow upward.

Inside the main body MB, flow paths ch1, ch3, and ch5 extending in the vertical direction are formed at positions overlapping with _{the top G1tp, bottom end G1bt1, and bottom end G1bt2 in the medium feed direction, respectively. In addition, flow paths ch2, ch4, and ch6 extending in the vertical direction are formed at positions overlapping with the top G2tp , bottom end G2bt1} , and bottom end _G2bt2 in the medium feed direction, respectively.

The lower end of the flow channel ch1 communicates with the groove G1 through an opening A1 formed at the apex _G1tp of the groove G1, and the upper end of the flow channel ch1 communicates with a connecting pipe CT1 on the upper surface MBu of the main body part MB. The upper end of the flow channel ch3 communicates with the groove G1 through an opening A3 formed at the lower end _G1bt1 of the groove G1, and the lower end of the flow channel ch3 communicates with a connecting pipe CT3 on the lower surface MBd of the main body part MB. The upper end of the flow channel ch5 communicates with the groove G1 through an opening A5 formed at the lower end _G1bt2 of the groove G1, and the lower end of the flow channel ch5 communicates with a connecting pipe CT5 on the lower surface MBd of the main body part MB.

The lower end of the flow channel ch2 communicates with the groove G2 through an opening A2 formed at the apex _G2tp of the groove G2, and the upper end of the flow channel ch2 communicates with a connecting pipe CT2 on the upper surface MBu of the main body part MB. The upper end of the flow channel ch4 communicates with the groove G2 through an opening A4 formed at the lower end _G2bt1 of the groove G2, and the lower end of the flow channel ch4 communicates with a connecting pipe CT4 on the lower surface MBd of the main body part MB. The upper end of the flow channel ch6 communicates with the groove G2 through an opening A6 formed at the lower end _G2bt2 of the groove G2, and the lower end of the flow channel ch6 communicates with a connecting pipe CT6 on the lower surface MBd of the main body part MB.

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 media width direction are approximately 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 by any fastener such as a screw, respectively, and cover the grooves G1 and G2. To more reliably seal the grooves G1 and G2, an O-ring extending along the contours of the grooves G1 and G2 may be provided between the main body MB and the lids 412 and 413.

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

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

<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.

As shown in Figures 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 stacked in this order from the top.

The alignment frame 51 is, for example, a flat plate member made of SUS. The alignment frame 51 has a central through hole TH ₅₁ that is rectangular in plan view and penetrates the center from top to bottom, and eight flow path through holes th ₅₁ that are circular in plan view and provided around the central through hole TH _51. The flow path through holes th ₅₁ are provided side by side in the medium feed direction, four on each side of the central through hole TH ₅₁ in the medium width direction.

The back-end frame 52 is, for example, a rectangular parallelepiped member made of resin. The back-end frame 52 has a central through-hole TH ₅₂ that is rectangular in plan view and penetrates the center from top to bottom, and eight flow path through-holes th ₅₂ that are circular in plan view and provided around the central through-hole TH _52. The flow path through-holes th ₅₂ are provided side by side in the medium feed direction, four on each side of the central through-hole TH ₅₂ in the medium width direction.

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 ₅₃ that is rectangular in plan view and that vertically penetrates the center, and eight flow path through-holes th ₅₃ that are generally rectangular in plan view and provided around the central through-hole TH _53. The flow path through-holes th ₅₃ are provided side by side in the medium feed direction, four on each side of the central through-hole TH ₅₃ in the medium width direction.

When the alignment frame 51, back-end frame 52, and front-end frame 53 are stacked in this order from the top, the central through hole TH ₅₁ of the alignment frame 51, the central through hole TH ₅₂ of the back-end frame 52, and the central through hole TH ₅₃ of the front-end frame 53 communicate with each other to form the central through hole TH ( FIG. 4 ). Furthermore, each of the eight flow path through holes th ₅₁ of the alignment frame 51, each of the eight flow path through holes th ₅₂ of the back-end frame 52, and each of the eight flow path through holes th ₅₃ of the front-end frame 53 communicate with each other to form eight flow path through holes th ( FIG. 4 ).

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

The connecting pipes CT3 to CT6 of the first flow path block 41 are inserted into the four flow path through holes th 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 the four flow path through holes th 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 circumferential surface of the flow path through holes th and the outer circumferential surface of the connecting pipes CT3 to CT6.

<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.

As shown in FIG. 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.

As shown in FIGS. 7 and 8, the flow passage CH includes eight ink circulation ports _CP61 , four manifold flow passages M1, M2, M3, and M4, and 48 individual flow passages ICH.

The eight ink circulation ports _CP61 are arranged side by side in the medium feed direction, four on each end of the flow path unit 61 in the medium width direction. Each of the eight ink circulation ports _CP61 is formed by providing a coaxial through hole in each of the ink sealing film 61A and the plates 61B and 61C.

Each of the four manifold flow paths M1 to M4 is a linear flow path that extends in the media 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 media feed direction.

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.

Each of the manifold channels M1 to M4 communicates with an ink circulation port _CP61 at both ends in the medium width direction.

Each of the 48 individual flow channels ICH includes a pressure chamber 1, a descender flow channel 2, and a nozzle 3, as shown in FIG. 8.

The pressure chamber 1 is a space for applying pressure to the ink by the piezoelectric actuator 62, and is formed by removing a portion 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 (Figure 7), and a flow path that extends to the manifold flow path M1 (or any of the manifold flow paths M2 to M4) is connected near one of the arc portions, and a descender flow path 2 is connected near the other arc portion.

The descender flow path 2 is a flow path that allows ink in the pressure chamber 1 to flow to the nozzle 3, and is formed by providing circular through holes coaxially in each of the plates 61C to 61E. The descender flow path 2 extends vertically from the pressure chamber 1 to the nozzle 3.

Nozzle 3 is a tiny opening that ejects ink toward the medium PM and is formed in the nozzle plate 61F.

Twelve individual flow channels ICH are connected to each of the four manifold flow channels M1 to M4. The twelve individual flow channels ICH connected to one manifold flow channel form an individual flow channel row L _ICH aligned in the medium width direction. In addition, the nozzles 3 of the twelve individual flow channels ICH forming one individual flow channel row L _ICH form a nozzle row L _3. The pressure chambers 1 of the multiple individual flow channels ICH included in each individual flow channel row L _ICH are connected only to the corresponding manifold flow channel and are not connected to other manifold flow channels. Therefore, only ink is supplied to the pressure chambers 1 of the multiple individual flow channels ICH included in each individual flow channel row L _ICH via the corresponding manifold flow channel. In this embodiment, each nozzle 3 included in a certain nozzle row L ₃ and each nozzle 3 included in a nozzle row L ₃ adjacent to the nozzle row are provided at positions slightly shifted in the medium width direction.

As shown in FIG. 8, the piezoelectric actuator 62 is composed of a first piezoelectric layer 621 provided on the upper surface of the flow passage 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.

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, covering 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, covering the entire first piezoelectric layer 621 and the common electrode 623.

The common electrode 623 is grounded via wiring (not shown) and is always maintained at ground potential.

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

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.

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

A number of contacts (not shown) are formed on the FPC 632 on the lower surface 631d side of the holding plate 631. Two driver ICs 633 are mounted on the FPC 632 on the upper surface 631u side of the holding plate 631.

The ejection control unit 63 is disposed on the upper surface of the piezoelectric actuator 62 so that each of the multiple contacts of the FPC 632 is electrically connected to each of the multiple individual electrodes 624 of the piezoelectric actuator 62. As a result, each of the multiple 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 of 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 of 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).

The head 60 is fixed to a lower surface 53d (FIG. 4) of the front end frame 53 of the frame member 50. In this state, the eight ink circulation ports _CP61 communicate with the eight flow path through holes th, respectively. In addition, the piezoelectric actuator 62 and the ejection control unit 63 are disposed inside the central through hole TH.

<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.

The 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 the flow path through hole th of the frame member 50.

Ink supplied from the subtank ST to the ink supply port _SP20 at the upstream end 20a of the ink supply tube 20 via the ink flow path member IC2 flows through the ink supply tube 20 to the branch 20x and then splits into two, one flowing toward the downstream end 20b1 of the ink supply tube 20 and the first flow path block 41, and the other flowing toward the downstream end 20b2 of the ink supply tube 20 and the second flow path block 42.

The ink flowing toward the first flow path block 41 passes through the connection pipe CT1 connected to the downstream end 20b1 of the ink supply pipe 20, reaches the groove G1, and is divided into two at the apex _G1tp of the groove G1.

One of the two split ink flows into the manifold M1 via a first portion G11 of the groove G1, the flow path ch3, the connecting tube CT3, the flow path through hole th of the frame member 50, and the ink circulation port _CP61 on the left side in the medium width direction and on the most discharge side in the medium feed direction of the head 60. The other of the two split ink flows into the manifold M3 via a second portion G12 of the groove G1, the flow path ch5, the connecting tube CT5, the flow path through hole th of the frame member 50, and the third ink circulation port _CP61 from the left side in the medium width direction and on the discharge side end of the head 60 in the medium feed direction.

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 is divided into two at the apex _G2tp of the groove G2.

One of the two split ink flows into the manifold M2 via a first portion G21 of the groove G2, the flow path ch4, the connecting tube CT4, the flow path through hole th of the frame member 50, and the second ink circulation port _CP61 from the right side in the medium width direction and the discharge side end in the medium feed direction of the head 60. The other of the two split ink flows into the manifold M4 via a second portion G22 of the groove G2, the flow path ch6, the connecting tube CT6, the flow path through hole th of the frame member 50, and the fourth ink circulation port _CP61 from the right side in the medium width direction and the discharge side end in the medium feed direction of the head 60.

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.

The ink that has passed through the manifold M1 and reached the ink circulation port _CP61 located on the right side in the medium width direction and on the most discharge side in the medium feed direction passes through the flow path through hole th of the frame member 50 and flows into the second flow path block from the connection pipe CT3 of the second flow path block 42. The ink that has passed through the manifold M3 and reached the third ink circulation port _CP61 from the right side in the medium width direction and the discharge side end in the medium feed direction passes through the flow path 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. These inks are joined at the apex G1 _tp of the recessed groove G1 of the second flow path block 42, and are sent from the ink discharge port _DP30 to the drain tank DT via the connection pipe CT1 of the second flow path block 42 and the ink discharge pipe 30.

The ink that has passed through the manifold M2 and reached the ink circulation port _CP61 located second from the left side in the medium width direction and the discharge side end in the medium feed direction 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 that has passed through the manifold M4 and reached the ink circulation port _CP61 located second from the left side in the medium width direction and the discharge side end in the medium feed direction 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 CT6 of the first flow path block 41. These inks are joined at the apex _G2tp of the recessed groove G2 of the first flow path block 41, and are sent from the ink discharge port _DP30 to the drain tank DT via the connection pipe CT2 of the first flow path block 41 and the ink discharge pipe 30.

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

Here, the flow path formed between the upstream end 20a of the ink supply tube 20 and the branch 20x is the 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 the first supply branch flow path _S1 , and the flow path to the head 60 via the second flow path block 42 is the second supply branch flow path _S2 .

The ink supply tube 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 channel _S1 is the same as the flow path resistance of the second supply branch channel _S2 . Specifically, for example, the ink supply tube 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 channel _S1 is the same as the flow path length of the second supply branch channel _S2 , and the cross-sectional area of the first supply branch channel _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 channel _S2 . This makes it possible to equalize the amount of ink sent from the branch 20x to the first and second supply branch channels _S1 , _S2 (branching of equal amounts is possible), and allows 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).

Of the first supply branch channels _S1 , the channel formed between the branch 20x of the ink supply tube and the apex _G1tp of the groove G1 of the first flow path block 41 is the first common supply branch channel _S10 , and the channels between the apex _G1tp and the manifolds M1 and M3 are the first and third branch supply branch channels _S11 and _S13 . Of the second supply branch channels _S2 , the channel formed between the branch 20x of the ink supply tube and the apex _G2tp of the groove G2 of the second flow path block 42 is the second common supply branch channel _S20 , and the channels between the apex _G2tp and the manifolds M2 and M4 are the second and fourth branch supply branch channels _S22 and _S24 . The grooves G1, G2 of the first and second flow path blocks 41, 42 may be configured so that the flow path length of the first part G11 and the second part G12 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, second, third and fourth branch supply sub-flow paths _S11 , _S22 , _S13 and _S24 .

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 .

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 _D1 is the same as the flow path resistance of the second discharge tributary _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 _D1 is the same as the flow path length of the second discharge tributary _D2 , and the cross-sectional area of the first discharge tributary _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 _D2 . This makes the amount of ink sent from the first and second discharge tributary _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).

Of the first discharge tributary channels _D1 , the channel formed between the branch 30x of the ink discharge tube and the apex _G2tp of the groove G2 of the first flow path block 41 is the first common discharge tributary channel _D10 , and the channels between the apex _G2tp and the manifolds M2 and M4 are the second and fourth branch discharge tributary channels _D12 and _D14 . Of the second discharge tributary channels _D2 , the channel formed between the branch 30x of the ink discharge tube 30 and the apex _G1tp of the groove G1 of the second flow path block 42 is the second common discharge tributary channel _D20 , and the channels between the apex _G1tp and the manifolds M1 and M3 are the first and third branch discharge tributary channels _D21 and _D23 . The grooves G1, G2 of the first and second flow path blocks 41, 42 may be configured so that the flow path length of the first part G11 and the second part G12 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, second, third and fourth branch discharge tributary flows _D21 , _D12 , _D23 and _D14 .

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 a resin pipe, 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 path _S1 with respect to the flow path resistance of the second supply branch path _S2 is within 10% of the flow path resistance of the second supply branch 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 path _D1 with respect to the flow path resistance of the second discharge branch path _D2 is within 10% of the flow path resistance of the second discharge branch path _D2 , equal branching can be realized and density unevenness (described in detail later) in image formation can be suppressed well.

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 entire flow path, the average value of the cross-sectional area throughout the entire 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.

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

First, the medium PM in the feed tray (not shown) is sent to the feed side of the transport rollers 801, and is then sent onto the platen 700 by the transport rollers 801. 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 on it is sent to the discharge side of the transport rollers 802, and is discharged to the discharge tray (not shown).

The ejection of ink droplets using the head system HS1 is performed by applying pressure to the ink in a specific pressure chamber 1 (referred to as the "target pressure chamber") using the 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. This generates an electric field parallel to the polarization direction 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 the 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 that communicates with the pressure chamber 1 via the descender flow path 2.

Ink in the subtank ST is continuously supplied to the pressure chamber 1 via the supply flow path S and manifolds M1 to M4. Any ink in the manifolds M1 to M4 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. The ink returned to the drain tank DT is returned to the subtank ST by the pump PP via a filter (not shown).

In the head system HS1 of this embodiment, the reason why the ink flow direction in the manifolds M1 and M3 is opposite to the ink flow direction in the manifolds M2 and M4 is as follows.

Generally, the ink ejected from the nozzles of the head experiences a temperature drop in the flow path that runs 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).

The inventors of the present invention have discovered that such a drop in ink temperature can cause a decrease in the quality of the image formed. Specifically, this is due to the following reasons:

Ink is a liquid and its viscosity changes depending on the temperature. In an individual flow path to which ink with a higher viscosity due to a drop in temperature 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 pressure chambers located further downstream. In this way, supplying high-viscosity ink to a specific pressure chamber reduces the amount of ink ejected from that pressure chamber, which can result in reduced quality, such as uneven density, in the image formed on the medium PM.

As a specific example, consider the case where ink is made to flow in the same direction through all of the manifolds M1 to M4 shown in Figure 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 path ICH near the left end on the upstream side, and relatively low temperature ink is supplied to the individual flow path ICH near the right end on the downstream side. Therefore, the amount of ink ejected from the nozzle 3 of the individual flow path ICH near the right end is less than the amount of ink ejected from the nozzle 3 of the individual flow path ICH near the left end, resulting in density unevenness in the formed image.

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.

Considering the manifolds M1 and M2 specifically, in the manifold M1, relatively high temperature ink is supplied to the individual flow paths ICH connected to the manifold M1 on the left side (upstream side) in the medium width direction, and relatively low temperature ink is supplied to the individual flow paths ICH connected to the manifold M1 on the right side (downstream side) in the medium width direction. Therefore, an image formed by ink ejection from the nozzle row _L3 of the pressure chamber row L _ICH connected to the manifold M1 tends to have a high density on the left side in the medium width direction and a decreasing density toward the right side.

On the other hand, in the manifold M2, relatively high temperature ink is supplied to the individual flow paths ICH connected to the manifold M2 on the right side (upstream side) in the medium width direction, and relatively low temperature ink is supplied to the individual flow paths ICH connected to the manifold M2 on the left side (downstream side) in the medium width direction. Therefore, an image formed by ink ejection from the nozzle row _L3 of the pressure chamber row _L1CH connected to the manifold M3 tends to have a high density on the right side in the medium width direction and a decreasing density going leftward.

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, an 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 an 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.

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 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 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 density unevenness in the head system HS1 of the first embodiment is performed by bringing inks ejected from adjacent nozzles close to or overlapping 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 deterioration of image quality without complicating the flow path structure or increasing the size of the head accordingly.

Similar cancellation (averaging) of density unevenness is also achieved between manifold M2 and manifold M3, and between manifold M3 and manifold M4.

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

The supply flow paths S and discharge flow paths 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.

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, for example, a manifold that is U-shaped in a plan view and extends from the 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, suppressing deterioration of image quality due to changes in ink temperature.

In the head system HS1 of the first embodiment, the first, second, third and fourth branched supply tributary channels _S11 , _S22 , _S13 and _S24 of the supply flow path S and the first, second, third and fourth branched discharge tributary channels _D21 , _D12 , _D23 and _D14 of the discharge flow path D are formed by first and second flow path blocks 41 and 42. In this way, by forming the area of the supply flow paths S and the discharge flow paths D where the second stage branching is performed and the number of flow paths is the largest inside a block-shaped member, it is possible to efficiently arrange the flow paths in the limited space on the head 60 and to miniaturize the head system HS1.

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

[Modification 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.

The head system HS1' of modification 1-1 has first and second flow path blocks 41', 42' (FIGS. 10(a) and 10(b)) instead of the first and second flow path blocks 41, 42 of the head system HS1 of the first embodiment. Since the rest of the configuration is the same as the head system HS1 of the first embodiment, a description thereof will be omitted.

The first and second flow path blocks 41' and 42' differ from the first and second flow path blocks 41 and 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.

Specifically, the lower end of the flow channel ch1 communicates with the groove G1 through an opening A1 formed at the apex _G1tp of the groove G1, and the upper end of the flow channel ch1 communicates with a connecting pipe CT1 on the upper surface MBu of the main body part MB. The upper end of the flow channel ch3 communicates with the groove G1 through an opening A3 formed at the lower end _G1bt1 of the groove G1, and the lower end of the flow channel ch3 communicates with a connecting pipe CT3 on the lower surface MBd of the main body part MB. The upper end of the flow channel ch6 communicates with the groove G1 through an opening A6 formed at the lower end _G1bt2 of the groove G1, and the lower end of the flow channel ch6 communicates with a connecting pipe CT6 on the lower surface MBd of the main body part MB.

The lower end of the flow channel ch2 communicates with the groove G2 through an opening A2 formed at the apex _G2tp of the groove G2, and the upper end of the flow channel ch2 communicates with a connecting pipe CT2 on the upper surface MBu of the main body part MB. The upper end of the flow channel ch4 communicates with the groove G2 through an opening A4 formed at the lower end _G2bt1 of the groove G2, and the lower end of the flow channel ch4 communicates with a connecting pipe CT4 on the lower surface MBd of the main body part MB. The upper end of the flow channel ch5 communicates with the groove G2 through an opening A5 formed at the lower end _G2bt2 of the groove G2, and the lower end of the flow channel ch5 communicates with a connecting pipe CT5 on the lower surface MBd of the main body part MB.

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.

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

The ink supply system ISS1' of modified example 1-1, which includes the head system HS1' of modified example 1-1, is provided with 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.

11, the ink flowing from the subtank ST toward the first flow path block 41' is divided into two at the top _G1tp of the groove G1, one of which flows into the manifold M1 via the first portion G11 of the groove G1, the flow path ch3, and the connecting tube CT3, and the other of which flows into the manifold M4 via the second portion G12 of the groove G1, the flow path ch6, and the connecting tube CT6. The ink flowing from the subtank ST toward the second flow path block 42' is divided into two at the top _G2tp of the groove G2, one of which flows into the manifold M2 via the first portion G21 of the groove G2, the flow path ch4, and the connecting tube CT4, and the other of which flows into the manifold M3 via the second portion G22 of the groove G2, the flow path ch5, and the connecting tube CT5.

The ink flowing 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 flowing into the second flow path block 42' from the connection pipe CT6 of the second flow path block 42' via the manifold M4 are joined at the apex G1 _tp of the recessed groove G1 of the second flow path block 42' and sent to the drain tank DT via the connection pipe CT1 of the second flow path block 42'. The ink flowing into the first flow path block 41' from the connection pipe CT4 of the first flow path block 41' via the manifold M2 and the ink flowing into the first flow path block 41' from the connection pipe CT5 of the first flow path block 41' via the manifold M3 are joined at the apex G2 _tp of the recessed groove G2 of the first flow path block 41' and sent to the drain tank DT via the connection pipe CT2 of the first flow path block 41'.

Here, the flow path formed between the upstream end 20a of the ink supply tube 20 and the branch 20x is the 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 the first supply branch flow path _S1 ', and the flow path to the head 60 via the second flow path block 42' is the second supply branch flow path _S2 '.

Of the first supply branch channels _S1 ', the channel formed between the branch 20x of the ink supply tube and the apex _G1tp of the groove G1 of the first flow path block 41 is the first common supply branch channel _S10 ', and the channels between the apex _G1tp and the manifolds M1 and M4 are the first and third branch supply branch channels _S11 ', _S13 '. Of the second supply branch channels _S2 ', the channel formed between the branch 20x of the ink supply tube and the apex _G2tp of the groove G2 of the second flow path block 42' is the second common supply branch channel _S20 ', and the channels between the apex _G2tp and the manifolds M2 and M3 are the second and fourth branch supply branch channels _S22 ', _S24 '.

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 '.

Of the first discharge tributary paths _D1 ', the path formed between the branch 30x of the ink discharge tube and the apex _G2tp of the groove G2 of the first flow path block 41' is the first common discharge tributary path _D10 ', and the paths between the apex _G2tp and the manifolds M2, M3 are the second and fourth branch discharge tributary paths _D12 ', _D14 '. Of the second discharge tributary paths _D2 ', the path formed between the branch 30x of the ink discharge tube 30 and the apex _G1tp of the groove G1 of the second flow path block 42' is the second common discharge tributary path _D20 ', and the paths between the apex _G1tp and the manifolds M1, M4 are the first and third branch discharge tributary paths _D21 ', _D23 '.

In the head system HS1' of variant 1-1, density unevenness is offset (averaged) between manifold M1 and manifold M2, and between manifold M3 and manifold M4, by a mechanism similar to that of head system HS1 of the first embodiment, thereby suppressing deterioration in the quality of the image formed.

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

In the supply flow path S of the head system HS1 of the first embodiment, the common supply flow path _S0 is branched at a branch 20x into first and second common supply tributary flow paths _S10 , _S20 , which are further branched into first, second, third and fourth branch supply tributary flow paths _S11 , _S22 , _S13 and _S24 in the first and second flow path blocks 41, 42, but is not limited to this. The supply flow path S may have any configuration that supplies ink to the manifolds M1, M3 from one side in the medium width direction, and supplies ink to the manifolds M2, M4 from the other side in the medium width direction.

Specifically, for example, a configuration in which the common supply flow path _S0 is branched into four, that is, a configuration in which the upstream ends of the first, second, third and fourth branched supply sub-flow paths _S11 , _S22 , _S13 and _S24 are connected to the downstream end of the common supply flow path _S0 may be adopted. 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 tube 20 and the first and second flow path blocks 41 and 42.

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

In the head system HS1 of the first embodiment, a tubular member that branches into two on the path may be used instead of the first and second flow path members 41 and 42. Also, the entire supply flow path S and/or the exhaust flow path D may be formed of a tubular member such as a resin tube.

In the head system HS1 of the first embodiment, most of the common supply flow path _S0 and the first and second common supply branch paths _S10 , _S20 are formed by the ink supply pipe 20, but this is not limited to this. The common supply flow path _S0 and the first and second common supply branch paths _S10 , _S20 may be formed, for example, inside the first and second flow path blocks 41, 42. Furthermore, the entire area of the supply flow path S and/or the discharge flow path D may be formed inside a block-shaped member.

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.

The head system HS1 of the first embodiment is configured to circulate ink through four manifolds, but is not limited to this. The head system HS1 may be configured to circulate ink through two manifolds, or may be configured to circulate 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 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.

A modified form in which ink flows in opposite directions in two manifolds adjacent to each other 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.

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

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 flow through one head unit 100. Specifically, the head system HS2 of the second embodiment uses a flow path member 70 (Figures 12 and 13) instead of the ink supply tube 20, ink discharge tube 30, first block flow path 41, and second block flow path 42 of the first embodiment.

The printing device 1000 used with the head system HS2 of the second embodiment has first and second sub-tanks (fill tanks) ST1 and ST2 instead of the sub-tank (fill tank) ST, and has first and second drain tanks DT1 and DT2 instead of the drain tank DT (Figure 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 composed of 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.

The rest of the configuration is the same as the head system HS1 of the first embodiment, so a description will be omitted.

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.

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 that protrudes from the left and lower corner of the main part MP in the media width direction to the feed side and downward, and a second base part BP2 that protrudes from the right and lower corner of the main part MP in the media width direction to the feed side and downward.

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

Ink circulation ports CP3 and CP4 are formed on the underside of 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 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.

A first groove GG1 and a second groove GG2 are formed on the inner surface MPi of the main part MP (the surface facing the discharge side in the media feed direction).

The first groove GG1 is approximately inverted V-shaped and includes a first portion GG11 extending downward from the top GG1 _tp and to the left in the medium width direction to a bottom end GG1 _bt1 , and a second portion GG12 extending downward from the top GG1 _tp and to the right in the medium width direction to a bottom end GG1 _bt2 .

The apex GG1 _tp is located to the left of the center of the inner surface MPi in the medium width direction. The bottom end GG1 _bt1 is located near the left end of the inner surface MPi, and the bottom end GG1 _bt2 is located near the right end of the inner surface MPi. When viewed in the medium feed direction, the bottom end GG1 _bt1 is located within the area where the first stand portion BP1 is provided, and the bottom end GG1 _bt2 is located within the area where the second stand portion BP2 is provided. Since the apex GG1 _tp is located to the left of the center of the inner surface MPi in the medium width direction, the flow path length of the first portion GG11 is shorter than the flow path length of the second portion GG12.

The extension 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). The first portion GG11 is bent twice on the path from the top GG1 _tp to the bottom end GG1 _bt1 , and the angle of inclination with respect to the up-down direction changes with each bend. Similarly, the second portion GG12 is bent twice on the path from the top GG1 _tp to the bottom end GG1 _bt2 , and the angle of inclination with respect to the up-down direction changes with each bend. In this way, when the flow path is extended in a direction different from the vertical direction, the extension direction of the flow path is inclined with respect to the horizontal direction to suppress the precipitation of the pigment on the bottom surface of the flow path, and thus it is possible to prevent the 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, it is possible to suppress the retention of air bubbles mixed in the ink on the upper surface of the flow path, and to more reliably flow upward. The inclination angle of the first portion GG11 and the second portion GG12 with respect to the vertical axis extending downward from the top GG1 _tp can be set to any angle equal to or less than 90°. In addition, the flow path length can be adjusted by changing the number of bends on the path. The flow path length can be increased by increasing the number of bends, and the flow path length can be decreased by decreasing the number of bends.

The second groove GG2 is formed above the first groove GG1. The second groove GG2 is substantially inverted V-shaped and includes a first portion GG21 extending downward and to the left in the medium width direction from the apex _GG2tp to a bottom end _GG2bt1 , and a second portion GG22 extending downward and to the right in the medium width direction from the apex _GG2tp to a bottom end _GG2bt2 .

The apex GG2 _tp is located to the right of the center of the inner surface MPi in the medium width direction. The lower end GG2 _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. When viewed in the medium feed direction, the lower end GG2 _bt1 is located within the area where the first stand portion BP1 is provided, and the lower end GG2 _bt2 is located within the area where the second stand portion BP2 is provided. Since the apex GG2 _tp is located to the right of the center of the inner surface MPi in the medium width direction, the flow path length of the second portion GG22 is shorter than the flow path length of the first portion GG21.

Inside the main part MP, flow paths cch1 and cch2 are formed in positions overlapping with the tops _GG1tp and _GG2tp in the medium width direction, respectively. The lower end of the flow path cch1 communicates with the first groove GG1 through an opening AA1 formed in the top _GG1tp of the first groove GG1, and the upper end of the flow path cch1 communicates with the ink flow port CP1 on the upper surface MPu of the main part MP. The lower end of the flow path cch2 communicates with the second groove GG2 through an opening AA2 formed in the top _GG2tp of the second groove GG2, and the upper end of the flow path cch2 communicates with the ink flow port CP2 on the upper surface MPu of the main part MP.

Inside the main portion MP and the base portion BP1, there is formed a flow path cch3 that connects the lower end portion GG1 _bt1 of the first groove GG1 to the ink circulation hole CP3 on the underside of the base portion BP1, and a flow path cch4 that connects the lower end portion GG2 _bt1 of the second groove GG2 to the ink circulation hole CP4 on the underside of the base portion BP1.

The upper end of the flow path cch3 communicates with the first groove GG1 through an opening AA3 formed at the lower end GG1 _bt1 of the first groove GG1. The flow path cch3 extends from the upper end to the feed side in the medium feed direction, then bends downward and extends to the ink circulation hole CP3. The upper end of the flow path cch4 communicates with the second groove GG2 through an opening AA4 formed at the lower end GG2 _bt1 of the second groove GG2. The flow path cch4 extends from the upper end to the feed side in the medium feed direction, then bends downward, passes beside the flow path cch3, and extends to the ink circulation hole CP4. As shown in FIG. 13, the flow path length of the region extending horizontally toward the feed side in the medium feed direction is longer in the flow path cch3 than in the flow path cch4.

Inside the main portion MP and the base portion BP2, there is formed a flow path cch5 that connects the lower end portion GG1 _bt2 of the first groove GG1 to the ink circulation hole CP5 on the underside of the base portion BP2, and a flow path cch6 that connects the lower end portion GG2 _bt2 of the second groove GG2 to the ink circulation hole CP6 on the underside of the base portion BP2.

The upper end of the flow path cch5 communicates with the first groove GG1 through an opening AA5 formed at the lower end GG1 _bt2 of the first groove GG1. The flow path cch5 extends from the upper end to the feed side in the medium feed direction, then bends downward and extends to the ink circulation hole CP5. The upper end of the flow path cch6 communicates with the second groove GG2 through an opening AA6 formed at the lower end GG2 _bt2 of the second groove GG2. The flow path cch6 extends from the upper end to the feed side in the medium feed direction, then bends downward and extends to the ink circulation hole CP6. As shown in FIG. 13, the flow path length of the region extending horizontally toward the feed side in the medium feed direction is longer in the flow path cch6 than in the flow path cch5. Furthermore, the flow path lengths of the regions extending horizontally toward the feeding side in the medium feeding direction are equal to each other in the flow paths cch3 and cch6, and are equal to each other in the flow paths cch4 and cch5.

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. That is, the difference in flow path length between the flow paths cch3 and cch5 caused by the position of the ink circulation port CP3 and the position of the ink circulation port CP5 being misaligned in the medium feed direction is offset by positioning the apex _GG1tp of the first groove GG1 on the left side in the medium width direction and making the flow path length of the first portion GG11 shorter than the flow path length of the second portion GG12.

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 flow port CP2 and the ink flow port CP4 is equal to the flow path length between the ink flow port CP2 and the ink flow port CP6.

The second flow path block 72 has a structure that is mirror-symmetrical to the first flow path block 71 in terms of the plane extending in the vertical direction and the medium width direction. In the following description, the parts of the second flow path block 72 that are in mirror-symmetrical positions to the parts of the first flow path block 71 are referred to by the same reference numerals as the parts of the first flow path block 71.

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

The first flow path block 71 and the second flow path block 72 are joined together with a rubber sheet 73 sandwiched therebetween, with the inner surfaces MPi of the respective main portions MP facing each other.

By covering the first groove GG1 and the second groove GG2 of the first and second flow path blocks 71 and 72 with a rubber sheet 73, a branch flow path consisting of the flow paths cch1, cch3, cch5 and the first groove GG1, and a branch flow path consisting of 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.

When the first flow path block 71 and the second flow path block 72 are joined, the ink flow ports CP3 and CP4 of the first flow path block 71 and the ink flow ports CP3 and 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 flow ports CP5 and CP6 of the first flow path block 71 and the ink flow ports CP5 and CP6 of the second flow path block 72 are aligned in the medium feed direction at the right end in the medium width direction.

As shown in FIG. 12, the flow path member 70 is connected to the upper surface of the frame member 50. In this state, the eight ink flow ports CP3 to CP6 of the flow path member 70 are connected to the eight flow path through holes th of the frame member 50, respectively.

<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.

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

Ink 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 reaches the first groove GG1 via the flow path cch1 and is divided into two at the top GG1 _tp of the first groove GG1.

One of the two split ink flows into the manifold M4 via the first portion GG11 of the first groove GG1, the flow path cch3, the ink circulation port CP3, the flow path through hole th of the frame member 50, and the ink circulation port _CP61 on the left side in the medium width direction and on the most feeding side in the medium feed direction of the head 60. The other of the two split ink flows into the manifold M3 via the second portion GG12 of the first groove GG1, the flow path cch5, the ink circulation port CP5, the flow path through hole th of the frame member 50, and the ink circulation port _CP61 on the right side in the medium width direction and second from the feeding side end in the medium feed direction of the head 60.

The ink that has passed through the manifold M4 and reached the ink circulation port _CP61 located on the right side in the medium width direction and on the most feeding side in the medium feed direction passes through the ink circulation port CP6 of the first flow path block 71, the flow path cch6, and the second portion GG22 of the second groove GG2, and reaches the apex _GG2tp of the second groove GG2. The ink that has passed through the manifold M3 and reached the ink circulation port _CP61 located on the left side in the medium width direction and second from the feeding side end in the medium feed direction passes through the ink circulation port CP4 of the first flow path block 71, the flow path cch4, and the first portion GG21 of the second groove GG2, and reaches the apex _GG2tp of the second groove GG2. These inks join at the apex _GG2tp , and flow 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.

The second supply flow path S2 for sending the yellow ink from the second sub-tank ST2 to the head 60, and the second discharge flow path D2 for sending the 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.

Ink supplied from the second sub-tank ST2 to the ink flow port CP2 (second supply port) of the second flow path block 72 via the ink flow path member IC2 passes through the flow path cch2 to reach the second groove GG2, and is divided into two at the top GG2 _tp of the second groove GG2.

One of the two split ink flows into the manifold M2 via a first portion GG21 of the second groove GG2, the flow path cch4, the ink circulation port CP4, the flow path through hole th of the frame member 50, and the third ink circulation port _CP61 from the left side in the medium width direction and the feed side end in the medium feed direction of the head 60. The other of the two split ink flows into the manifold M1 via a second portion GG22 of the second groove GG2, the flow path cch6, the ink circulation port CP6, the flow path through hole th of the frame member 50, and the fourth ink circulation port _CP61 from the right side in the medium width direction and the feed side end in the medium feed direction of the head 60.

The ink that has passed through the manifold M2 and reached the third ink circulation port _CP61 from the right side in the medium width direction and the feed side end in the medium feed direction passes through the ink circulation port CP5 of the second flow path block 72, the flow path cch5, and the second part GG12 of the first groove GG1, and reaches the apex _GG1tp of the first groove GG1. The ink that has passed through the manifold M1 and reached the fourth ink circulation port _CP61 from the left side in the medium width direction and the feed side end in the medium feed direction passes through the ink circulation port CP3 of the second flow path block 72, the flow path cch3, and the first part GG11 of the first groove GG1, and reaches the apex _GG1tp of the first groove GG1. These inks join at the apex _GG1tp , and flow through the flow path cch1, the ink circulation port CP1 (second outlet), and the ink flow path 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.

Here, of the first supply flow path S1, the flow path formed between the ink circulation port CP1 (first supply port) of the first flow path block 71 and the apex _GG1tp of the first groove GG1 is a common supply flow path (first common supply flow path) _S10 , and the flow paths from the apex _GG1tp to the manifolds M4 and M3 are supply branch flow paths (first supply branch flow paths) _S11 .

The first flow path block 71 and the frame member 50 may be configured so that the flow path resistance of the two supply branch paths S1 ₁ is the same. Specifically, for example, the first flow path block 71 may be configured so that the flow path lengths of the two supply branch paths S1 ₁ are the same, and the cross-sectional areas (cross-sectional areas of the planes perpendicular to the flow path extension direction) of the two supply branch paths S1 ₁ are the same. This makes the amount of ink sent from the top GG1 _tp of the first groove GG1 to each of the two supply branch paths S1 ₁ equal (equal amount branching is possible), and ink can 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.

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 different from the vertical direction and intersects with a plane (horizontal plane) that includes the media width direction and the media feed direction is more than half the flow path length of the first supply flow path S1.

Of the first discharge flow paths D1, the flow path formed between the ink circulation port CP2 (first discharge port) of the first flow path block 71 and the apex _GG2tp of the second groove GG2 is a common discharge flow path (first common discharge flow path) _D10 , and the flow paths from the apex _GG2tp to the manifolds M4 and M3 are discharge tributary flow paths (first discharge tributary flow paths) _D11 .

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 D1 ₁ 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 D1 ₁ are the same, and the cross-sectional areas (cross-sectional areas of the planes perpendicular to the direction in which the paths extend) of the two discharge tributary paths D1 ₁ are the same. This makes the amount of ink sent from each of the two discharge tributary paths D1 ₁ toward the top GG2 _tp of the second groove GG2 equal (equal amounts can be branched), 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.

The first flow path block 71 may be configured so that the flow path length of the region (inclined portion) of the second groove GG2 that extends in a direction different from the vertical direction and intersects with a plane (horizontal plane) that includes the media width direction and the media feed direction is more than half the flow path length of the first discharge flow path D1.

Of the second supply flow paths S2, the flow path formed between the ink circulation port CP2 (second supply port) of the second flow path block 72 and the apex _GG2tp of the second groove GG2 is a common supply flow path (second common supply flow path) _S20 , and the flow paths from the apex _GG2tp to the manifolds M2 and M1 are supply branch flow paths (second supply branch flow paths) _S21 .

Of the second discharge flow paths D2, the flow path formed between the ink circulation port CP1 (second discharge port) of the second flow path block 72 and the apex _GG1tp of the first groove GG1 is a common discharge flow path (second common discharge flow path) _D20 , and the flow paths from the apex _GG1tp to the manifolds M2 and M1 are discharge tributary flow paths (second discharge tributary flow paths) _D21 .

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 independent ink flow paths as flow paths of approximately the same quality, making it less likely that a difference in flow rate will occur between the two flow paths, and thus making it possible to more effectively suppress deterioration in image quality.

In this embodiment, for example, if the error of the flow resistance of one of the two supply tributaries S1 ₁ relative to the flow resistance of the other of the two supply tributaries S1 ₁ is within 10% of the flow resistance of the other of the two supply tributaries S1 ₁ , 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 D1 ₁ relative to the flow resistance of the other of the two discharge tributaries D1 ₁ is within 10% of the flow resistance of the other of the two discharge tributaries D1 ₁ , equal branching can be realized and density unevenness in image formation can be suppressed favorably. Furthermore, 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.

As described above with respect to this specification and the present invention, 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 area throughout the flow path may be used. Furthermore, 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 a liquid flowing through a certain flow path relative to the flow velocity of a liquid flowing through another flow path is within 10% of the flow velocity of the liquid flowing through the other flow path.

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

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

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 to each other. Therefore, density unevenness that may occur in an image formed by the nozzle row _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.

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, for example, a manifold that is U-shaped in a plan view and extends from the 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 due to changes in ink temperature is suppressed.

The head system HS2 of the second embodiment has 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. Therefore, two different types of ink can be circulated through a single head.

In the head system HS2 of the second embodiment, most of the supply flow path S1 and discharge flow path D1 are formed by an integral flow path block 71, and most of the supply flow path S2 and 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 positioned above the head 60. This allows the flow paths to be efficiently arranged in the limited space on the head 60, making it possible to miniaturize the head system HS2. Furthermore, forming the flow paths from POM or the like can increase the durability of the flow paths against ink.

The ink supply system ISS2, printing device 1000, and ink distribution method of the second embodiment also achieve the same effects as the head system HS2.

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

In the ink supply system ISS2' of modified example 2-1, similar 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 the second flow path block 72 of the flow path member 70 and the 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.

As shown in FIG. 15, in the ink supply system ISS2' of variant 2-1, the second sub-tank ST2 and the ink flow port CP1 of the second flow path block 72 are connected by the 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 the ink flow path member IC3.

Ink 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 to the first groove GG1, and is divided into two at the top GG1 _tp of the first groove GG1.

One of the two ink streams flows into the manifold M1 from the right side in the medium width direction via the first part GG11 of the first groove GG1, the flow path cch3, and the ink flow port CP3. The other of the two ink streams flows into the manifold M2 from the right side in the medium width direction via the second part GG12 of the first groove GG1, the flow path cch5, and the ink flow port CP5.

The ink that has reached the ink circulation 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 apex _GG2tp of the second groove GG2. The ink that has reached the ink circulation 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 apex _GG2tp of the second groove GG2. These inks join at the apex _GG2tp and flow through the flow path cch2, the ink circulation port CP2 (second outlet), and the ink flow path member IC3 to the drain tank DT2.

Of the second supply flow paths S2', the flow path formed between the ink circulation port CP1 (second supply port) of the second flow path block 72 and the apex _GG1tp of the first groove GG1 is a common supply flow path (second common supply flow path) _S20 ', and the flow paths from the apex _GG1tp to the manifolds M2 and M1 are supply branch paths (second supply branch paths) _S21 '.

Of the second discharge flow paths D2', the flow path formed between the ink circulation port CP2 (second discharge port) of the second flow path block 72 and the apex _GG2tp of the second groove GG2 is a common discharge flow path (second common discharge flow path) _D20 ', and the flow paths from the apex _GG2tp to the manifolds M2 and M1 are discharge tributary paths (second discharge tributary paths) _D21 '.

In the ink supply system ISS2' of variant 2-1, as shown in FIG. 15, in manifolds M1 and M4, ink flows toward the right side in the medium width direction, and in manifolds M2 and M3, ink flows toward the left 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.

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 side in the medium width direction in the manifolds M1 and M4, and ink flows toward the right side in the medium width direction in the manifolds M2 and M3.

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

In the ink supply system ISS2" of 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. As other points are the same as the ink supply system ISS2 of the second embodiment, a description thereof will be omitted.

The flow path block 70" differs from the flow path block 70 of the second embodiment in that it includes a first flow path block 71" instead of the first flow path block 71.

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 in the first flow path block 71.

Specifically, the upper end of the flow path cch3 communicates with the first groove GG1 through an opening AA3 formed at the lower end GG1 _bt1 of the first groove GG1. The flow path cch3 extends from the upper end to the feed side in the medium feed direction, then bends downward and extends to the ink circulation hole CP4. The upper end of the flow path cch4 communicates with the second groove GG2 through an opening AA4 formed at the lower end GG2 _bt1 of the second groove GG2. The flow path cch4 extends from the upper end to 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 path length of the region extending horizontally toward the feed side in the medium feed direction is longer in the flow path cch4 than in the flow path cch3.

The upper end of the flow path cch5 communicates with the first groove GG1 through an opening AA5 formed at the lower end GG1 _bt2 of the first groove GG1. The flow path cch5 extends from the upper end to the feed side in the medium feed direction, then bends downward and extends to the ink circulation hole CP6. The upper end of the flow path cch6 communicates with the second groove GG2 through an opening AA6 formed at the lower end GG2 _bt2 of the second groove GG2. The flow path cch6 extends from the upper end to the feed side in the medium feed direction, then bends downward, and extends to the ink circulation hole CP5 by passing beside the flow path cch5. As shown in FIG. 16, the flow path length of the region extending horizontally toward the feed side in the medium feed direction is longer in the flow path cch5 than in the flow path cch6. Furthermore, the flow path lengths of the regions extending horizontally toward the feeding side in the medium feeding direction are equal to each other in the flow paths cch3 and cch6, and are equal to each other in the flow paths cch4 and cch5.

In the first flow path block 71", the flow path length of the flow path between the opening AA1 and the ink circulation port CP4 is shorter than the flow path length of the flow path 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 flow paths are equal. Note that the flow _path length between the opening AA1 and the ink circulation port CP4 and the flow path between the opening AA1 and the ink circulation port CP6 may be made equal to each other by changing the number of bends of the first groove GG11 and the second groove GG12 or shifting the position of the apex GG1 tp in the medium width direction. In this case, the cross-sectional areas of both flow paths may be equal to each other.

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

The ink supply system ISS2" of variant 2-2 includes a flow path block 70" instead of the flow path block 70, and thereby forms supply flow paths S1" and D1" (Figure 17) instead of the supply flow path S1 and the discharge flow path D1.

Specifically, as shown in FIG. 17, ink supplied from the first sub-tank ST1 to an ink circulation port (first supply port) CP1 of the first flow path block 71″ via the ink flow path member IC2 passes through a flow path cch1 and reaches the first groove GG1, and is divided into two at a top _GG1tp of the first groove GG1.

One of the two ink streams flows into the manifold M3 from the left side in the medium width direction via the first part GG11 of the first groove GG1, the flow path cch3, and the ink flow port CP4. The other of the two ink streams flows into the manifold M4 from the right side in the medium width direction via the second part GG12 of the first groove GG1, the flow path cch5, and the ink flow port CP6.

After flowing rightward through the manifold M3, the ink flows in from the ink circulation 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 apex _GG2tp of the second groove GG2. After flowing leftward through the manifold M4, the ink flows in from the ink circulation 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 apex _GG2tp of the second groove GG2. These inks join at the apex _GG2tp , and flow to the drain tank DT1 through the flow path cch2, the ink circulation port (first discharge port) CP2, and the ink flow path member IC3. The ink in the first drain tank DT1 is sent to the first sub-tank ST1 by the first pump PP1.

Here, of the first supply flow paths S1", the flow path formed between the ink circulation port CP1 (first supply port) of the first flow path block 71" and the apex _GG1tp of the first groove GG1 is the common supply flow path (first common supply flow path) _S10 ", and the flow paths from the apex _GG1tp to the manifolds M4 and M3 are respectively supply branch flow paths (first supply branch flow paths) _S11 ". Of the first discharge flow paths D1", the flow path formed between the ink circulation port CP2 (first discharge port) of the first flow path block 71" and the apex _GG2tp of the second groove GG2 is the common discharge flow path (first common discharge flow path) _D10 ", and the flow paths from the apex _GG2tp to the manifolds M4 and M3 are respectively discharge branch flow paths (first discharge branch flow paths) _D11 ".

In the ink supply system ISS2" of variant 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.

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 first flow path block 71" described above (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, the ink flows toward the right side in the medium width direction, and in the manifolds M2 and M3, the ink flows toward the left side in the medium width direction.

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 modified embodiment 2-1, and the head system provided in the ink supply system ISS" of modified embodiment 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 modified embodiment.

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 be configured to 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. In addition, 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 essentially be used as a single supply and discharge flow path.

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

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 capable of covering the first and second grooves GG1 and GG2 of the first and second flow path blocks 71 and 72 to form a flow path may be used, and a material that further exerts a function of suppressing the hydraulic pressure fluctuation caused by the change in flow rate through deformation (damper function) is preferable. It is preferable to form the sheet from a material that is more flexible than the material from which the first and second flow path blocks 71 and 72 are formed, but this is not limited to this. The first and second grooves GG1 and GG2 can also be covered to form a flow path using a material that has less deflection than rubber, such as resin or metal.

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

In addition, in the head systems HS1, HS2, and each of the modified examples, at least one of the manifolds M1 to M4 may branch in the media feed direction in at least a portion of the area between both ends, as in the manifold M shown in FIG. 18.

The manifold M shown in FIG. 18 branches into three small manifolds Ma, Mb, and Mc spaced apart in the media feed direction between the left and right ends in the media width direction. The small manifolds Ma, Mb, and Mc are parallel to each other. Each of the small manifolds Ma, Mb, and Mc is connected to a plurality of individual flow paths (not shown) aligned in the media width direction. 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 image quality degradation based on the mechanism of the present invention.

The embodiments described herein are illustrative in all respects and should not be considered limiting. For example, the number and configuration of the head units 100 may be changed. There is no limit to the number of colors that the printing device 1000 can print simultaneously, and the printing device 1000 may be configured to be capable of single-color printing only. The number and arrangement of the individual flow channels ICH may also be changed as appropriate. Furthermore, the technical features described in each embodiment may be combined with each other.

As long as the characteristics of the present invention are maintained, the present invention is not limited to the above-described embodiment, and other forms that are conceivable within the scope of the technical concept of the present invention are also included within the scope of the present invention.

The head system of the present invention can suppress degradation of image quality caused by changes in ink temperature.

Reference Signs List 1 Pressure chamber 3 Nozzle 20 Ink supply pipe 30 Ink discharge pipe 41, 71 First flow path block 42, 72 Second flow path block 50 Frame member 60 Head 70 Flow path member 100 Head unit 700 Platens 801, 802 Transport roller 1000 Printing device

Claims (27)

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;
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 . 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. 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. 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. 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. 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. 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 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. 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;
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. A head system according to 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. 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. The head system according to claim 10, wherein the first discharge flow path is formed by the groove and the elastic member. 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. The head system according to any one of claims 1 to 12, wherein in each of the first and second groups, the pressure chambers included in a specific group are supplied with liquid only via the manifold included in that specific group. The head system according to any one of claims 1 to 13, 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 vertical direction. 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. 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 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. 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. 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 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. 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. 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. 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. A head system according to 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. 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 . 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. 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. A liquid supply system according to claim 24 or 25 ;
A printing device comprising a medium transport unit that transports a medium. A liquid flowing method for flowing a liquid within the head of a head system using the head system according to any one of claims 1 to 23 .

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