Head unit and inkjet recording device

Abstract

To provide a head unit of an inkjet recording device that enables recording using color ink, white ink and a reaction liquid, which achieves both miniaturization of the head unit and facilitation of exchange of a head.SOLUTION: A head unit includes a first head where a nozzle array for discharging a reaction liquid reacting with any one of color ink and white ink is formed, and a second head where a nozzle array for discharging color ink and a nozzle array for discharging white ink are formed, wherein the first head and the second head are arranged side by side in a main scanning direction, so that the nozzle array of the reaction liquid is positioned at a position closest to a first end which is one end in a main scanning direction in a head unit, and the nozzle array of the white ink is positioned at a position closest to a second end which is the other end.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a head unit and an inkjet recording apparatus. [Background technology]

[0002] In recent years, in the field of inkjet printers, in order to output high-quality printed matter even with liquid ejection head scanning type liquid ejection devices, there is a demand for ink circulation type liquid ejection devices that can use special inks in conjunction with high quality recording media. In order to obtain even higher image quality, configurations that combine reactive liquid with color inks and configurations that add white ink are also being considered.

[0003] Patent Document 1 describes an inkjet printer that uses ultraviolet-curable color ink, white ink, and clear ink. In the inkjet head of Patent Document 1, a nozzle row that ejects color ink and a nozzle row that ejects white ink and clear ink are arranged side by side along the main scanning direction and are arranged offset in the sub-scanning direction. The nozzle rows of color ink are arranged so as to sandwich the nozzle row of clear ink from both sides in the main scanning direction, and external light irradiators are provided at both ends of the inkjet head in the main scanning direction so as to sandwich the nozzle row of color ink from both sides. This ensures a distance between the ultraviolet irradiator and the nozzle of clear ink, and prevents the nozzle of clear ink from clogging due to stray light of the irradiation light from the ultraviolet irradiator. Patent Document 2 describes a printing method that forms a color image by depositing color inks on a medium, characterized in that white ink is used in addition to the color inks. Also, a printing method is known in which a reaction liquid containing a component that increases the viscosity of the ink is applied onto the recording medium before the ink is ejected, thereby immediately fixing the ink that has reached the recording medium, suppressing color mixing, and improving image quality. Also, a head unit may be configured in which the white ink head and the reaction liquid head are each configured as single-color heads, and are combined with heads of other colors and arranged in the main scanning direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-185737 A [Patent Document 2] JP 2004-25603 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the inkjet printer of Patent Document 1, the color ink heads and the white ink and clear ink heads are arranged offset in the sub-scanning direction, which causes a problem of the head unit becoming larger in the sub-scanning direction. In addition, the color ink heads are arranged on both sides of the clear ink and white ink heads in the main scanning direction, so the carriage movement distance is the same between a printing mode that does not use clear ink or white ink and a printing mode that uses clear ink or white ink. Therefore, there is room for improvement in the printing throughput depending on the printing mode. In addition, in a head unit configured such that the white ink head and the reaction liquid head are each configured as single-color heads and are combined with other color ink heads and arranged in the main scanning direction, it is easy to replace the heads, but the head unit becomes larger in the main scanning direction.

[0006] The present invention relates to a head unit of an inkjet recording device capable of recording using color inks, white ink, and a reaction liquid, and is characterized by its miniaturization of the head unit and ease of head replacement. Achieve both. [Means for solving the problem]

[0007] The present invention provides a head unit of an inkjet recording device having a plurality of heads each having a nozzle array formed with a plurality of nozzles for ejecting liquid, the head unit performing recording by ejecting liquid while moving back and forth in a main scanning direction onto a recording medium, The plurality of heads include a first head in which a nozzle row is formed to eject a reaction liquid that reacts with at least one of the color ink and the white ink; a second head in which a nozzle row for ejecting the color inks and a nozzle row for ejecting the white ink are formed; Including, The first head and the second head are the nozzle row for the reaction liquid is located at a position closest to a first end, which is one end of the head unit in the main scanning direction, and the nozzle row for the white ink is located at a position closest to a second end, which is the other end of the head unit in the main scanning direction; The head units are characterized in being arranged in line along the main scanning direction. Effect of the Invention

[0008] According to the present invention, in a head unit of an inkjet recording device capable of recording using color inks, white ink, and reaction liquid, it is possible to achieve both a compact head unit and ease of head replacement. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a liquid ejection device according to an embodiment of the present invention; [Diagram 2] FIG. 2 is an exploded perspective view of a liquid ejection head according to an embodiment of the present invention; FIG. [Diagram 3] FIG. 2 is a schematic diagram of a head unit according to the first embodiment. [Figure 4] 5A to 5C are schematic diagrams illustrating the movement range of a head unit in different print modes in the first embodiment. [Diagram 5] FIG. 2 is a schematic diagram illustrating a layer structure of a printed matter in Example 1. [Figure 6] FIG. 11 is a schematic diagram of a head unit according to a second embodiment. [Figure 7] FIG. 11 is a schematic diagram of a head unit according to a third embodiment. [Figure 8] 13 is a schematic diagram for explaining the direction in which a printed matter is viewed in the third embodiment. FIG. [Figure 9] FIG. 11 is a schematic diagram illustrating a layer structure of a printed matter in Example 3. [Figure 10] 5A and 5B are diagrams illustrating the ink flow in the ejection unit of the embodiment. [Figure 11] FIG. 2 is a schematic cross-sectional view of a discharge unit according to an embodiment of the present invention. [Figure 12] FIG. 1 is a diagram illustrating a liquid ejection device. [Figure 13] FIG. 2 is an exploded perspective view of the liquid ejection head. [Figure 14] 2A and 2B are a longitudinal section of a liquid ejection head and an enlarged cross-sectional view of an ejection module. [Figure 15] FIG. 2 is a schematic view showing the appearance of a circulation unit. [Figure 16] FIG. [Figure 17] FIG. 4 is a block diagram showing a schematic diagram of a circulation path. [Figure 18] FIG. 4 is a cross-sectional view showing an example of a pressure adjusting means. [Figure 19] FIG. 2 is an external perspective view of a circulation pump. [Figure 20] IX-IX line cross-sectional view of the circulating pump shown in FIG. [Figure 21] 3A and 3B are diagrams illustrating the flow of ink in a liquid ejection head. [Figure 22] FIG. 4 is a schematic diagram showing a circulation path in the discharge unit. [Figure 23] FIG. 3 shows an aperture plate 330. [Figure 24] FIG. 2 is a diagram showing a discharge element substrate. [Diagram 25] 5A and 5B are cross-sectional views showing the ink flow in the ejection unit. [Figure 26] FIG. 4 is a cross-sectional view showing the vicinity of a discharge port. [Figure 27] FIG. 11 is a cross-sectional view showing a comparative example near the ejection port. [Figure 28] 11A and 11B are diagrams showing a comparative example of a discharge element substrate. [Figure 29] FIG. 2 is a diagram showing a flow path configuration of a liquid ejection head. [Diagram 30]2A and 2B are diagrams illustrating a connection state between a main body of the liquid ejection device and a liquid ejection head. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative positions, etc. of the components described in the embodiments are not intended to limit the scope of the present invention unless otherwise specified.

[0011] 1 is a schematic diagram of a liquid ejection device 50 (recording device) which is an inkjet recording device using a head unit 10. The liquid ejection device 50 of the embodiment is a serial scan type inkjet recording device which ejects ink from the head unit 10 to record an image on a recording sheet S. The head unit 10 is mounted on a carriage 60, which moves in the main scanning direction of the arrow X along a guide shaft 51. The carriage 60 is reciprocated in the main scanning direction X by a carriage motor 105 (see FIG. 12), which is a driving means provided in the liquid ejection device 50. The recording sheet S is transported by transport rollers 55, 56, 57, and 58 in the sub-scanning direction of the arrow Y which intersects with the main scanning direction (orthogonal in this example).

[0012] The head unit 10 is made up of a plurality of liquid ejection heads 1 (for example, a first head 1a, a second head 1b, and a third head 1c), and the plurality of liquid ejection heads 1 are arranged side by side along the main scanning direction. A circulation unit 54 is mounted on the plurality of liquid ejection heads 1, and ink is circulated for each ink. While FIG. 1 illustrates a configuration in which the head unit 10 has three liquid ejection heads 1, this is merely an illustrative example, and the number of liquid ejection heads 1 that the head unit 10 has is not limited to this.

[0013] The liquid ejection device 50 is provided with an ink tank 2 and an external pump 21, which are ink supply sources. The ink stored in the ink tank 2 is supplied to the circulation unit 54 through an ink supply tube 59 by the driving force of the external pump 21. The ink supply tube 59 includes electrical wiring required for printing and piping for supplying air to the head unit 10 and the carriage 60. The head unit 10 is capable of high-quality full-color printing using a reaction liquid, white ink, and a plurality of color inks. The reaction liquid contains a component that increases the viscosity of the ink, and by applying the reaction liquid to the recording sheet S before ink ejection, the ink that has reached the recording sheet S can be immediately fixed, color mixing can be suppressed, and high image quality can be achieved. In the following description, the reaction liquid, white ink, and color ink may be collectively referred to simply as ink. A cap member is disposed at a position away from the conveyance path of the recording sheet S, and when no recording operation is performed, the cap member moves relatively to a position covering the face surface of the head unit 10 to prevent the ejection port from drying and to perform a suction operation for filling and recovery.

[0014] FIG. 2(a) shows an exploded perspective view of the liquid ejection head 1. FIG. 2(b) is a perspective view of the assembled state of the various parts, and FIG. 2(c) shows a view seen from the arrow A in FIG. 2(b). The liquid ejection head 1 has a circulation unit 54 which is a circulating device that supplies liquid to ejection ports 331 (see FIGS. 10 and 11) from which the liquid is ejected, and collects liquid that has not been ejected from the ejection ports 331 and supplies it again to the ejection ports 331. As the circulation units 54 correspond to each ink, the number of units to be mounted is determined according to the type of ink. In this embodiment, for example, the configuration includes circulation units 54a, 54b, 54c, and 54d for four colors. The circulation units 54a to 54d are each mounted in a head housing 53. Connected.

[0015] The head housing 53 has a joint surface 111 for receiving ink from the liquid ejection device 50, and the joint surface 111 has joints 111a, 111b, 111c, and 111d that are in communication with the circulation units 54a to 54d, respectively. When mounted on the liquid ejection device 50, supply tubes (not shown) corresponding to each ink are connected to the joints 111a to 111d from the liquid ejection device 50 side. Each ink supplied from an ink tank 2 provided in the device body of the liquid ejection device 50 through a supply tube passes through the joints 111a to 111d of the head housing 53, respectively, and is supplied to the circulation units 54a to 54d, respectively.

[0016] The head housing 53 is provided with a wiring board 23 (PWB) that receives an electric signal from the main body of the liquid ejection device 50. A support member 213 on which an ejection module 300 (comprised of an aperture plate 330 and a recording element substrate 340, see FIG. 10(a)) is mounted is connected to a bottom surface 113 of the head housing 53. In the embodiment, as shown in FIG. 2(c), two ejection modules 300a and 300b are provided on the bottom surface 113 of the head housing 53. The ejection module 300 is formed with a nozzle row 332 (see FIG. 10) composed of a plurality of ejection ports (nozzles) 331 (see FIG. 11) that eject liquid. The nozzle row 332 extends in the Y direction, and a plurality of nozzle rows 332 are arranged in the X direction. The head unit 10 has a plurality of liquid ejection heads 1 with the nozzle rows 332 formed therein, and performs printing by ejecting liquid while moving back and forth along the main scanning direction X to a recording sheet S, which is a recording medium. The discharge module 300, the support member 213, and the electric wiring member 22 (FPC) constitute the discharge unit 20. The discharge unit 20 and the head housing 53 constitute the liquid discharge head 1.

[0017] The ink supplied to the circulation units 54a to 54d is supplied to the support member 213 via the head housing 53. The ejection module 300 and the support member 213 are bonded with an adhesive. The ejection module 300 includes a silicon substrate having a thickness of 0.5 to 1 mm and an energy generating element provided on one side of the silicon substrate for ejecting liquid. As shown in FIG. 11(a) and FIG. 11(b), in the embodiment, a plurality of heat generating resistor elements 36 (heaters) are used as the energy generating elements, and electrical wiring for supplying power to each of the heat generating resistor elements 36 is formed on the silicon substrate by a film forming technique. A plurality of pressure chambers 325 corresponding to the heat generating resistor elements 36 and a plurality of ejection ports 331 for ejecting ink are formed on the silicon substrate by a photolithography technique. A common supply flow path 321 for supplying ink to the plurality of pressure chambers 325, a plurality of plate supply ports 311, and a common recovery flow path 322 for recovering ink from the pressure chambers 325 and a plurality of plate recovery ports 312 are opened on the rear surface of the silicon substrate.

[0018] The ink flow in the discharge unit 20 will be described with reference to FIG. 10(a) and FIG. 10(b). FIG. 10(a) is an exploded perspective view of the discharge unit 20 seen from the support member 213 side, and FIG. 10(b) is an exploded perspective view of the discharge unit 20 seen from the recording element substrate 340 side. For simplification, the connection substrate and the electric substrate are omitted. The ink flow will be described for only one color, but the other colors are similar. The ink flow path in the discharge unit 20 is formed by the support member 213 and the discharge module 300. Furthermore, the discharge module 300 is formed by the aperture plate 330 and the recording element substrate 340. The nozzle plate 320 having the discharge port 331 formed therein is provided on the surface of the recording element substrate 340 opposite to the aperture plate 330. The aperture plate 330 is connected to the surface of the recording element substrate 340 opposite to the nozzle plate 320. The surface of the aperture plate 330 opposite to the recording element substrate 340 is joined to the support member 213. This causes the discharge module 300 to be fixed to the support member 213 .

[0019] Arrows R1 and R2 shown in FIG. 10(a) and FIG. 10(b) indicate the above-mentioned support member 213 and the opening The diagram shows the flow of ink between the plate 330 and the recording element substrate 340. A solid arrow R1 indicates the flow of ink supplied to the recording element substrate 340, and a dashed arrow R2 indicates the flow of ink recovered from the recording element substrate 340 to the support member 213 side. A plate supply port 311 and a plate recovery port 312 are provided in the aperture plate 330. A support member supply port 211 and a support member recovery port 212 are provided in the support member 213. The supply ink flow indicated by arrow R1 passes through the support member supply port 211 and the plate supply port 311, and the recovered ink flow indicated by arrow R2 passes through the plate recovery port 312 and the support member recovery port 212.

[0020] FIG. 11(a) shows a schematic cross-sectional view of the plate supply port 311 section perpendicular to the Y direction, and FIG. 11(b) shows a schematic cross-sectional view of the plate recovery port 312 section perpendicular to the Y direction. Note that the ink flow will be described using one opening of each member, but the ink flow is similar for any opening. First, ink is supplied from the head housing 53 side to the support member supply port 211 of the support member 213, and then ink is supplied from the support member supply port 211 to the common supply flow channel 321 of the recording element substrate 340 via the plate supply port 311. After that, ink is supplied from the common supply flow channel 321 to the pressure chamber 325 via the supply connection flow channel 323. Next, the flow of recovery will be described. Of the ink supplied to the pressure chamber 325, the ink that was not ejected from the ejection port 331 flows to the common recovery flow channel 322 via the recovery connection flow channel 324. The liquid then flows from the common recovery passage 322 through the plate recovery port 312 of the opening plate 330 to the support member recovery port 212 of the support member 213 , and is then recovered on the head housing 53 side.

[0021] As shown in FIG. 11(a) and FIG. 11(b), the flow of ink connecting the support member 213 to the common supply flow path 321 and the common recovery flow path 322 occurs at the location where the plate supply port 311 and the plate recovery port 312 are present. Note that other areas where there are no plate supply port 311 or plate recovery port 312 serve as areas in the support member 213 to separate the support member supply port 211 and the support member recovery port 212. This area is used as an adhesion area when the ejection module 300 and the support member 213 are adhered to each other, and therefore the support member 213 does not have an opening. Therefore, in areas where there are no plate openings or support member openings, there is no direct connection between the ink in the common supply flow path 321 and the common recovery flow path 322 and the ink on the support member 213 or head housing 53 side, as shown in FIG. 11(c).

[0022] Ink flows in such a way that ink is supplied from the support member 213 from the location where the plate supply port 311 is open as shown in Fig. 11(a). Furthermore, ink flows from the supply connection flow path 323 to the pressure chamber 325, and then flows into the common recovery flow path 322 via the recovery connection flow path 324. As shown in the cross section of Fig. 11(a), there is no plate recovery port 312 on the common recovery flow path 322 side at this time. Therefore, once ink flows through a region where no opening exists in the opening plate 330 as shown in Fig. 11(c), and when it reaches a region where the plate recovery port 312 exists as shown in Fig. 11(b), a flow of ink flows into the common recovery flow path 322.

[0023] As described above, the common supply flow path 321 and the common recovery flow path 322 are separate flow paths. The common supply flow path 321 has a supply connection flow path 323 that supplies ink to the ejection port 331, and the common recovery flow path 322 has a recovery connection flow path 324 that recovers ink from the ejection port 331. In other words, since the ejection port 331 is located in the path connecting the supply connection flow path 323 and the recovery connection flow path 324, an ink flow from the supply connection flow path 323 side to the recovery connection flow path 324 side occurs in the pressure chamber 325 near the ejection port 331. This ink circulation keeps the ink in the pressure chamber 325 always fresh, and can prevent problems such as concentration changes and adhesion due to ink evaporation.

[0024] Example 1 Example 1 will be described with reference to Figures 3, 4, and 5. Figure 3 is a schematic diagram of the head unit 10 as viewed from the top (ink ejecting side) of the liquid ejection device 50. The head unit 10 is composed of a first head 1a and a second head 1b, and the first head 1a and the second head 1b are arranged to be aligned in the main scanning direction. One end (end on the +X direction side) of the head unit 10 in the main scanning direction X is called the first end 10a, and the other end (end on the -X direction side) is called the second end 10b. The second head 1b is arranged on the side closer to the second end 10b than the first head 1a.

[0025] The first head 1a is a head in which a nozzle row 332 of a reaction liquid that reacts with at least one of a color ink and a white ink is formed. In the first embodiment, the first head 1a is a head dedicated to reaction liquid in which a nozzle row 332 that ejects a white ink reaction liquid RCTW and a nozzle row 332 that ejects color ink reaction liquids RCTC1 and RCTC2 are formed. The second head 1b is a head in which a nozzle row 332 that ejects color inks and a nozzle row 332 that ejects white ink are formed. In the first embodiment, the second head 1b is formed with nozzle rows 332 that eject each of the inks black K, light cyan LC, cyan C, yellow Y, light magenta LM, magenta M, orange OR, gray GY, and white W.

[0026] In the first head 1a, a nozzle row 332 for the white ink reaction liquid RCTW is formed at a position closest to the first end portion 10a. In the second head 1b, a nozzle row 332 for the white ink W is formed at a position closest to the second end portion 10b.

[0027] The first head 1a and the second head 1b are arranged such that the nozzle row 332 of the reaction liquid RCT is located at a position closest to the first end 10a of the head unit 10, and the nozzle row 332 of the white ink W is located at a position closest to the second end 10b. In the first embodiment, when the first head 1a and the second head 1b are aligned in the main scanning direction, the nozzle rows 332 of the white ink reaction liquid RCTW and the white ink W are arranged at both ends of the head unit 10, respectively.

[0028] The first head 1a may be configured to have only the nozzle row 332 for the color ink reaction liquid RCTC, or may be configured to have only the nozzle row 332 for the white ink reaction liquid RCTW. When the first head 1a has the nozzle row 332 for the color ink reaction liquid RCTC and the nozzle row 332 for the white ink reaction liquid RCTW, either one may be disposed at a position closest to the first end 10a. The types and arrangement of the color inks in the second head 1b are not limited to the above example.

[0029] Since ink types of the same system are collected in one head, and the first head 1a and the second head 1b are arranged at the same position in the sub-scanning direction Y, the carriage 60 can be made more compact. Furthermore, the smaller movement range of the carriage 60 allows the liquid ejection device 50 to be made more compact. Furthermore, since the first head 1a is dedicated to the reaction liquid, it has a large effect on the heating resistor element 36 and has a short lifespan, but since it is separate from the second head 1b for the main color ink, there is the advantage that head replacement is easy.

[0030] FIG. 4 is a schematic diagram illustrating the movement range of the head unit 10 depending on the printing mode. The liquid ejection device 50 of the first embodiment can perform recording in any one of a plurality of printing modes. The plurality of printing modes include a first mode to a fourth mode. In the first mode, recording is performed using color inks, white ink, a reaction liquid for color ink, and a reaction liquid for white ink. In the second mode, recording is performed using only color inks and a reaction liquid for color ink. In the third mode, recording is performed using only color inks and white ink. In the fourth mode, recording is performed using only color inks. The printing mode using white ink is used when recording is performed on a transparent recording sheet S, for example. The printing mode using reaction liquid is used to obtain high-quality recording. It is used when you want to do the following.

[0031] FIG. 4(a) shows the movement range of the head unit 10 when printing in the first mode, FIG. 4(b) shows the movement range of the head unit 10 when printing in the second mode, FIG. 4(c) shows the movement range of the head unit 10 when printing in the third mode, and FIG. 4(d) shows the movement range of the head unit 10 when printing in the fourth mode. The direction toward the first end 10a in the main scanning direction is the forward direction (+X direction), and the direction toward the second end 10b is the return direction (-X direction). Of the recording range SR where recording is performed on the recording sheet S, the end closer to the first end 10a in the main scanning direction is the third end Sa, and the end closer to the second end 10b is the fourth end Sb. Note that the dashed line indicating the recording sheet S in FIG. 4(a) has been omitted in FIG. 4(b) to FIG. 4(d) to avoid cluttering the figures.

[0032] 4(a), in the first mode, when the carriage 60 is moved in the +X direction toward the first end 10a, it is moved to a position where the nozzle row of the white ink W of the second head 1b passes the third end Sa. When the carriage 60 is moved in the -X direction toward the second end 10b, it is moved to a position where the nozzle row of the white ink reaction liquid RCTW of the first head 1a passes the fourth end Sb.

[0033] As shown in Fig. 4(b) , in the second mode, when the carriage 60 is moved in the +X direction toward the first end 10a, it is moved to a position where the nozzle row of the color ink adjacent to the nozzle row of the white ink W of the second head 1b passes the third end Sa. In the example of Fig. 4(b) , this color ink is gray GY. Also, when the carriage 60 is moved in the -X direction toward the second end 10b, it is moved to a position where the nozzle row of the color ink reaction liquid RCTC of the first head 1a passes the fourth end Sb.

[0034] 4(c), in the third mode, when the carriage 60 is moved in the +X direction toward the first end 10a, it is moved to a position where the nozzle row of the white ink W of the second head 1b passes the third end Sa. Also, when the carriage 60 is moved in the -X direction toward the second end 10b, it is moved to a position where the nozzle row of the color ink (black K) closest to the first end 10a of the second head 1b passes the fourth end Sb.

[0035] As shown in Fig. 4(d) , in the fourth mode, when the carriage 60 is moved in the +X direction toward the first end 10a, it is moved to a position where the nozzle row of the color ink adjacent to the nozzle row of the white ink W of the second head 1b passes the third end Sa. In the example of Fig. 4(d) , this color ink is gray GY. Also, when the carriage 60 is moved in the -X direction toward the second end 10b, it is moved to a position where the nozzle row of the color ink (black K) closest to the first end 10a of the second head 1b passes the fourth end Sb.

[0036] 4(b), in the second mode, the movement distance of the carriage 60 is shorter than in the first mode by a distance X1 corresponding to the width of the nozzle row of the white ink W when moving in the +X direction, and by a distance X2 corresponding to the width of the nozzle row of the white ink reaction liquid RCTW when moving in the -X direction.

[0037] As shown in FIG. 4(c), in the third mode, compared to the first mode, the movement distance of the carriage 60 is shorter by the distance X3 between the nozzle row closest to the first end 10a of the first head 1a and the nozzle row closest to the first end 10a of the second head 1b when moving in the -X direction.

[0038] 4(d), in the fourth mode, the movement distance of the carriage 60 when moving in the +X direction is shorter than in the first mode by a distance X1 equivalent to the width of the nozzle row of the white ink W. Also, when moving in the -X direction, the movement distance is shorter by a distance X3 between the nozzle row closest to the first end 10a of the first head 1a and the nozzle row closest to the first end 10a of the second head 1b.

[0039] Therefore, in the second, third and fourth modes, compared to the first mode, it is possible to print faster by the amount of the reduction in the movement distance of the carriage 60, thereby improving throughput. If the ratio of print modes used by users is, for example, 5% for the first mode and 95% for the fourth mode, the improvement in throughput in the fourth mode will greatly contribute to improving user convenience.

[0040] FIG. 5 is a schematic diagram showing the layer structure when double-sided printing is performed on a transparent recording sheet S. As described above, when printing on a transparent recording sheet S, white ink W is used to create a base. FIG. 5(A) shows the layer structure when printing in a three-layer print mode in which color ink 31, white ink 30, and color ink 31 are printed in this order on a transparent recording sheet S. FIG. 5(B) shows the layer structure when printing in a five-layer print mode in which color ink 31, white ink 30, black ink 32, white ink 30, and color ink 31 are printed in this order on a transparent recording sheet S. The three-layer print mode is used when the images on both sides are the same, and the five-layer print mode is used when the images on both sides are different.

[0041] In order to reliably eject a special ink such as a reaction liquid, a preliminary ejection may be performed immediately before printing on the recording sheet S. In the liquid ejection device 50 of the first embodiment, the preliminary ejection is performed at a position beyond the end of the -X direction side of the passing range of the recording sheet S on the -X direction side. In the head unit 10 of the first embodiment, the nozzle row 332 of the reaction liquid RCTW for white ink is located at the end of the +X direction side, so in the three-layer printing mode and the five-layer printing mode in which double-sided printing is performed on the transparent recording sheet S, one-way printing is performed in which recording is performed only during movement in the +X direction. When using white ink W or when printing color inks with higher image quality, it is desirable to apply the reaction liquid first. Therefore, when the position where the preliminary ejection is performed is at the end of the -X direction as in the first embodiment, it is appropriate to position the nozzle row 332 of the reaction liquid at the end of the +X direction of the head unit 10 as in the first embodiment. Conversely, when the position where the preliminary ejection is performed is at the end of the +X direction, it is appropriate to position the nozzle row 332 of the reaction liquid at the end of the -X direction of the head unit 10. The first embodiment is more effective when an ink circulation configuration is applied, and can also be applied to a circulation configuration for a piezo head.

[0042] Example 2 Example 2 will be described with reference to Fig. 6. Fig. 6 is a schematic diagram of the head unit 10 as viewed from the top (the side from which ink is ejected) of the liquid ejection device 50. The head unit 10 is composed of a first head 1a, a second head 1b, and a third head 1c, and these multiple heads are arranged to line up in the main scanning direction X. The second head 1b is arranged on the side closer to the second end 10b than the first head 1a. The third head 1c is arranged on the side closer to the second end 10b than the second head 1b.

[0043] The first head 1a is a head in which a nozzle row 332 that ejects a reaction liquid that reacts with at least one of a color ink and a white ink is formed. In the second embodiment, the first head 1a is a head dedicated to reaction liquids in which a nozzle row 332 that ejects a white ink reaction liquid RCTW and color ink reaction liquids RCTC1 and RCTC2 are formed. The second head 1b is a head in which a nozzle row 332 that ejects color inks is formed. In the second embodiment, the second head 1b is formed with a nozzle row 332 that ejects each of the inks black K, light cyan LC, cyan C, yellow Y, light magenta LM, and magenta M. The third head 1c is a head in which a nozzle row 332 for white ink and a nozzle row 332 for color inks are formed. In the second embodiment, the third head 1c is formed with a nozzle row 332 that ejects each of the inks orange OR, gray GY, and white ink W.

[0044] In the first head 1a, the second head 1b, and the third head 1c, the nozzle row 332 of the reaction liquid RCT is located at a position closest to the first end 10a of the head unit 10, and the nozzle row 332 of the reaction liquid RCT is located at a position closest to the second end 10 b. In the second embodiment, the nozzle row 332 of the white ink W is located at the position closest to the first end 10a in the first head 1a. In the third head 1c, the nozzle row 332 of the white ink W is formed at the position closest to the second end 10b. In the third head 1c, the nozzle row 332 of the gray GY is formed adjacent to the nozzle row 332 of the white ink W on the side closer to the first end 10a than the nozzle row 332 of the white ink W. As a result, when the first head 1a, the second head 1b, and the third head 1c are aligned along the main scanning direction X, the nozzle rows 332 of the white ink reaction liquid RCTW and the white ink W are arranged at both ends of the head unit 10 in the main scanning direction X.

[0045] The first head 1a may be configured to have only the nozzle row 332 for the color ink reaction liquid RCTC, or may be configured to have only the nozzle row 332 for the white ink reaction liquid RCTW. When the first head 1a has the nozzle row 332 for the color ink reaction liquid RCTC and the nozzle row 332 for the white ink reaction liquid RCTW, either one may be disposed at a position closest to the first end 10a. The types and arrangement of the color inks in the second head 1b and the third head 1c are not limited to the above example. The third head 1c may be configured to have only the nozzle row 332 for ejecting the white ink W.

[0046] Ink types of the same system are collected in one head, and the first head 1a, the second head 1b, and the third head 1c are arranged at the same position in the sub-scanning direction Y. This allows the carriage 60 to be made smaller, and the movement range of the carriage 60 to be reduced, allowing the liquid ejection device 50 to be made smaller.

[0047] Also, the white ink W and the reaction liquid RCT have a greater effect on the heating resistor element 36 than the other color inks, and the heads equipped with them have a shorter lifespan. However, the first head 1a in which only the reaction liquid RCT is integrated, and the third head 1c equipped with the white ink W are independent from the second head 1b equipped with the other color inks, so there is an advantage in that the heads can be easily replaced. From the viewpoint of image quality change, it is desirable for the color inks to be combined with the white ink W in the third head 1c to be special colors (e.g., orange OR, gray GY) that are used in image formation less frequently. Even if color mixing occurs between the nozzle rows 332, it is possible to suppress the change in the color of the white ink W by arranging gray GY next to the white ink W, which is desirable from the viewpoint of reliability. In addition, the first head 1a and the third head 1c, which are frequently replaced, can be made common, so costs can be reduced. In the second embodiment, the effect is greater when an ink circulation configuration is applied, and it can also be applied to a circulation configuration of a piezo head.

[0048] Also, similar to the first embodiment, by controlling the movement range of the carriage 60 so that the nozzle rows 332 of the ink that is not used in each print mode do not pass through the recording range SR, it is possible to improve the throughput in the second to fourth modes.

[0049] In the first mode, when the carriage 60 is moved in the +X direction toward the first end 10a, it is moved to a position where the nozzle row of the white ink W of the third head 1c passes the third end Sa. When the carriage 60 is moved in the -X direction toward the second end 10b, it is moved to a position where the nozzle row of the white ink reaction liquid RCTW of the first head 1a passes the fourth end Sb.

[0050] In the second mode, when the carriage 60 is moved in the +X direction toward the first end 10a, it is moved to a position where the nozzle row of the color ink (gray GY) adjacent to the nozzle row of the white ink W of the third head 1c passes the third end Sa. Also, when the carriage 60 is moved in the -X direction toward the second end 10b, it is moved to a position where the nozzle rows of the color ink reaction liquids RCTC1 and RCTC2 of the first head 1a pass the fourth end Sb.

[0051] In the third mode, when the carriage 60 is moved in the +X direction toward the first end 10a, it is moved to a position where the nozzle row of the white ink W of the third head 1c passes the third end Sa. When the carriage 60 is moved in the -X direction toward the second end 10b, it is moved to a position where the nozzle row of the color ink (black K) closest to the first end 10a of the second head 1b passes the fourth end Sb.

[0052] In the fourth mode, when the carriage 60 is moved in the +X direction toward the first end 10a, it is moved to a position where the nozzle row of the color ink (gray GY) adjacent to the nozzle row of the white ink W of the third head 1c passes the third end Sa. Also, when the carriage 60 is moved in the -X direction toward the second end 10b, it is moved to a position where the nozzle row of the color ink (black K) closest to the first end 10a of the second head 1b passes the fourth end Sb.

[0053] Example 3 Example 3 will be described with reference to Figures 7, 8 and 9. Figure 7 is a schematic diagram of the head unit 10 as viewed from the top (the side from which ink is ejected) of the liquid ejection device 50. The head unit 10 is made up of a first head 1a, a second head 1b and a third head 1c, and these multiple heads are arranged to line up in the main scanning direction X. The second head 1b is arranged on the side closer to the second end 10b than the first head 1a. The third head 1c is arranged on the side closer to the second end 10b than the second head 1b.

[0054] The first head 1a is a head in which a nozzle row 332 that ejects a reaction liquid that reacts with at least one of a color ink and a white ink and a nozzle row 332 that ejects a white ink are formed. In the third embodiment, the first head 1a is formed with a nozzle row 332 that ejects a white ink reaction liquid RCTW, a white ink W, and a color ink reaction liquid RCTC. The second head 1b is a head in which a nozzle row 332 that ejects a color ink is formed. In the third embodiment, the second head 1b is formed with a nozzle row 332 that ejects each of black K, light cyan LC, cyan C, yellow Y, light magenta LM, magenta M, orange OR, and gray GY. The third head 1c is a head in which a nozzle row 332 that ejects a reaction liquid that reacts with at least one of a color ink and a white ink and a nozzle row 332 that ejects a white ink are formed. In the third embodiment, the third head 1c, like the first head 1a, is formed with nozzle rows 332 that eject the white ink reaction liquid RCTW, the white ink W, and the color ink reaction liquid RCTC.

[0055] The first head 1a, the second head 1b, and the third head 1c are arranged so that the nozzle row 332 of the reaction liquid RCT is located at the position closest to the first end 10a of the head unit 10, and the nozzle row 332 of the reaction liquid RCT is located at the position closest to the second end 10b. In the third embodiment, the nozzle row 332 of the white ink reaction liquid RCTW, the nozzle row 332 of the white ink W, and the nozzle row 332 of the color ink reaction liquid RCTC are formed in this order from the side closest to the first end 10a in the first head 1a. In addition, the nozzle row 332 of the white ink reaction liquid RCTW, the nozzle row 332 of the white ink W, and the nozzle row 332 of the color ink reaction liquid RCTC are formed in this order from the side closest to the second end 10b in the third head 1c. As a result, the color arrangement order of the first head 1a and the third head 1c is such that the white ink reaction liquid RCTW and the color ink reaction liquid RCTC are arranged at both ends in the main scanning direction X. When the first head 1a, the second head 1b, and the third head 1c are aligned along the main scanning direction X, the nozzle rows 332 of the first head 1a and the third head 1c are arranged symmetrically with respect to the color ink group of the second head 1b. That is, the nozzle rows 332 for the white ink reaction liquid RCTW are arranged at both ends in the main scanning direction X, the white ink W is arranged inside thereof, and the color ink reaction liquid RCTC is arranged further inside thereof.

[0056] The arrangement order of the white ink W, the white ink reaction liquid RCTW, and the color ink reaction liquid RCTC in the first head 1a and the third head 1c is not limited to the above example, as long as there are reaction liquid nozzle rows 332 positioned near both ends of the head unit 10 in the main scanning direction.

[0057] Fig. 8 is a schematic diagram showing a printout with an image formed on a transparent recording sheet S attached to a glass plate G (e.g., a window or a showcase) and viewed from the direction of the arrow. Fig. 8(A) shows the case where the printout is attached to the front of the glass plate G as seen by the observer, and Fig. 8(B) shows the case where the printout is attached to the rear side of the glass plate G as seen by the observer, for example, the case where the printout is attached to the inside of a showcase.

[0058] FIG. 9 is a schematic diagram showing the layer structure of the printed matter described in FIG. 8(A) and FIG. 8(B). As described above, when printing on a transparent recording sheet S, white ink is used to create a base. FIG. 9(A) shows the printed matter of FIG. 8(A), where white ink 30 and color ink 31 are printed in this order on a transparent recording sheet S. FIG. 9(B) shows the printed matter of FIG. 8(B), where color ink 31 and white ink 30 are printed in this order on a transparent recording sheet S. When printing the printed matter of FIG. 9(A) using the head unit 10 of the third embodiment, printing is performed in the order of the first head 1a and the second head 1b in the forward direction (+X direction). In the return direction (-X direction), printing is performed in the order of the third head 1c and the second head 1b. Therefore, bidirectional printing is possible, and high-speed printing is possible. Also, when printing the printed matter of FIG. 9(B), in the forward direction (+X direction), the first head 1a prints the reaction liquid for color ink RCTC, the second head 1b prints the reaction liquid for white ink RCTW, and the third head 1c prints the reaction liquid for white ink RCTW. In the backward direction (-X direction), the third head 1c prints the white ink W. Therefore, the printing speed is slightly slower, but this is possible. Also, when printing on a non-transparent recording sheet S, it is not necessary to apply white ink, and the head unit 10 can be used to print the reaction liquid for color ink RCTC first in both directions, making high-speed printing possible. In the third embodiment, the application of an ink circulation configuration provides a greater effect, and it can also be applied to a circulation configuration for a piezo head.

[0059] Also, similar to the first embodiment, by controlling the movement range of the carriage 60 so that the nozzle rows 332 of the ink that is not used in each print mode do not pass through the recording range SR, it is possible to improve the throughput in the second to fourth modes.

[0060] In the first mode, when the carriage 60 is moved in the +X direction toward the first end 10a, it is moved to a position where the nozzle row of the white ink reaction liquid RCTW of the third head 1c passes the third end Sa. When the carriage 60 is moved in the -X direction toward the second end 10b, it is moved to a position where the nozzle row of the white ink reaction liquid RCTW of the first head 1a passes the fourth end Sb.

[0061] In the second mode, when the carriage 60 is moved in the +X direction toward the first end 10a, it is moved to a position where the nozzle row of the color ink reaction liquid RCTC of the third head 1c passes the third end Sa. When the carriage 60 is moved in the -X direction toward the second end 10b, it is moved to a position where the nozzle row of the color ink reaction liquid RCTC of the first head 1a passes the fourth end Sb.

[0062] In the third mode, when the carriage 60 is moved in the +X direction toward the first end 10a, it is moved to a position where the nozzle row of the white ink W of the third head 1c passes the third end Sa. When the carriage 60 is moved in the -X direction toward the second end 10b, it is moved to a position where the nozzle row of the white ink W of the first head 1a passes the fourth end Sb.

[0063] In the fourth mode, when the carriage 60 is moved in the +X direction toward the first end 10a, When the carriage 60 is moved in the -X direction toward the second end 10b, the nozzle row of the color ink (gray GY) closest to the second end 10b of the second head 1b is moved to a position where it passes the third end Sa. When the carriage 60 is moved in the -X direction toward the second end 10b, the nozzle row of the color ink (black K) closest to the first end 10a of the second head 1b is moved to a position where it passes the fourth end Sb.

[0064] According to the above embodiment, since the positions of the multiple liquid ejection heads 1 in the head unit 10 in the sub-scanning direction are not shifted, the size of the head unit 10 in the sub-scanning direction can be suppressed. In addition, since the liquid ejection head in which the nozzle row 332 of the reaction liquid is formed and the liquid ejection head in which the nozzle row 332 of the color ink is formed are independent, efficient replacement is possible even if the replacement cycle (life) of the two is different. In particular, in the third embodiment, since the liquid ejection head in which the nozzle row 332 of the reaction liquid and the white ink is formed and the liquid ejection head in which the nozzle row 332 of the color ink is formed are independent, more efficient replacement is possible. In addition, the movement amount of the carriage 60 can be shortened in a printing mode that does not use white ink or reaction liquid, and throughput can be improved. In addition, in three-layer printing and five-layer printing when printing on both sides of a transparent sheet, high-quality printing can be achieved by first applying the reaction liquid. In addition, bidirectional printing can be performed while using the white ink first and then again, and high-speed printing can be achieved.

[0065] <Liquid discharge device> Fig. 1 is a diagram for explaining a liquid ejection device to which the present invention can be applied, and is an enlarged view of a liquid ejection head of the liquid ejection device and its surroundings. First, a schematic configuration of a liquid ejection device 50 in this embodiment will be described with reference to Fig. 1. Fig. 1 is a perspective view that shows a liquid ejection device that uses a liquid ejection head 1. The liquid ejection device 50 of this embodiment constitutes a serial type inkjet recording device that performs recording on a recording sheet S by ejecting ink as a liquid while scanning the liquid ejection head 1.

[0066] The liquid ejection head 1 is mounted on a carriage 60. The carriage 60 moves back and forth in the main scanning direction (X direction) along a guide shaft 51. The recording sheet S is transported in a sub-scanning direction (Y direction) that intersects (orthogonal in this example) the main scanning direction by transport rollers 55, 56, 57, and 58. In each of the figures referred to below, the Z direction indicates the vertical direction, and intersects (orthogonal in this example) the XY plane defined by the X and Y directions. The liquid ejection head 1 is configured to be removable and attachable to the carriage 60 by the user.

[0067] The liquid ejection head 1 includes a circulation unit 54 and an ejection unit 3 (see FIG. 13) described later. The specific configuration will be described later, but the ejection unit 3 is provided with a plurality of ejection ports and energy generating elements (hereinafter referred to as ejection elements) that generate ejection energy for ejecting liquid from each ejection port.

[0068] The liquid ejection device 50 is also provided with an ink tank 2, which is an ink supply source, and an external pump 21, and the ink stored in the ink tank 2 is supplied to the circulation unit 54 via an ink supply tube 59 by the driving force of the external pump 21.

[0069] The liquid ejection device 50 repeats a printing scan in which the liquid ejection head 1 mounted on the carriage 60 moves in the main scanning direction while ejecting ink to perform printing, and a transport operation in which the recording sheet S is transported in the sub-scanning direction. In this way, a predetermined image is formed on the recording sheet S. Note that the liquid ejection head 1 in this embodiment is capable of ejecting a reaction liquid, a white ink, and a plurality of color inks, and a full-color image can be recorded using these liquids. Note that in the following description, the reaction liquid, white ink, and color inks will be collectively referred to simply as ink. The color inks may include black (K), yellow (Y), magenta (M), cyan (C), light cyan (LC), light magenta (LM), orange (OR), gray (GY), and the like. However, the color inks that can be ejected from the liquid ejection head 1 are not limited to the inks exemplified here, and do not necessarily include all of the inks listed here. The present disclosure is also applicable to liquid ejection heads for ejecting other types of ink. In other words, the types and number of inks ejected from the liquid ejection head are not limited.

[0070] Furthermore, the liquid ejection device 50 is provided with a cap member (not shown) capable of covering the ejection port surface on which the ejection ports of the liquid ejection head are formed, at a position offset in the X direction from the transport path of the recording sheet S. The cap member covers the ejection port surface of the liquid ejection head 1 during non-recording operations, and is used to prevent and protect the ejection ports from drying, and to suck ink from the ejection ports, etc.

[0071] The head unit 10 shown in FIG. 1 includes three liquid ejection heads 1, a first head 1a, a second head 1b, and a third head 1c. An example is shown in which one liquid ejection head 1 is provided with four circulation units 54 corresponding to four types of liquid (reaction liquid, white ink, and color ink). However, the configuration of the head unit 10 is not limited to this, and it is sufficient that the head unit 10 is provided with a circulation unit 54 corresponding to the type of liquid to be ejected. Also, multiple circulation units 54 may be provided for the same type of liquid. In other words, the liquid ejection head 1 can be configured to include one or more circulation units. It is also possible to configure the head unit 10 to circulate at least one ink rather than circulating all four types of ink.

[0072] FIG. 12 is a block diagram showing a control system of the liquid ejection device 50. The CPU 103 functions as a control means for controlling the operation of each part of the liquid ejection device 50 based on a program such as a processing procedure stored in the ROM 101. The RAM 102 is used as a work area when the CPU 103 executes processing. The CPU 103 receives image data from a host device 400 outside the liquid ejection device 50, controls the head driver 1A, and controls the driving of the ejection elements provided in the ejection unit 3. The CPU 103 also controls the drivers of various actuators provided in the liquid ejection device. For example, the CPU 103 controls a motor driver 105A of a carriage motor 105 for moving the carriage 60, a motor driver 104A of a conveying motor 104 for conveying the recording sheet S, and the like. The CPU 103 also controls a pump driver 500A for driving a circulation pump 500 described later, a pump driver 21A of an external pump 21, and the like. Although FIG. 12 shows a form in which processing is performed upon receiving image data from the host device 400, processing may be performed by the liquid ejection device 50 independently of data from the host device 400.

[0073] <Basic configuration of liquid ejection head> Fig. 13 is an exploded perspective view of the liquid ejection head 1 of this embodiment. Fig. 14 is a cross-sectional view taken along line IIIa-IIIa of the liquid ejection head 1 shown in Fig. 13. Fig. 14(a) is an overall vertical cross-sectional view of the liquid ejection head 1, and Fig. 14(b) is an enlarged view of the ejection module shown in Fig. 14(a). The basic structure of the liquid ejection head 1 of this embodiment will be described below, mainly with reference to Fig. 13 and Fig. 14, and with appropriate reference to Fig. 1.

[0074] 13, the liquid ejection head 1 includes a circulation unit 54 and an ejection unit 3 for ejecting ink supplied from the circulation unit 54 onto a recording sheet S. The liquid ejection head 1 in this embodiment is fixedly supported on a carriage 60 of a liquid ejection device 50 by positioning means and electrical contacts (not shown) provided on the carriage 60. The liquid ejection head 1 ejects ink while moving together with the carriage 60 in the main scanning direction (X direction) shown in FIG. 1, and performs recording on the recording sheet S.

[0075] The external pump 21 connected to the ink tank 2, which is the ink supply source, is provided with an ink supply channel. A tube 59 is provided (see FIG. 1). A liquid connector (not shown) is provided at the end of this ink supply tube 59. When the liquid ejection head 1 is mounted on the liquid ejection device 50, the liquid connector provided at the end of the ink supply tube 59 is airtightly connected to a liquid connector insertion port 53a, which is a liquid inlet port provided in a head housing 53 of the liquid ejection head 1. As a result, an ink supply path is formed from the ink tank 2 to the liquid ejection head 1 via the external pump 21. In this embodiment, since four types of ink are used, four sets of the ink tank 2, the external pump 21, the ink supply tube 59, and the circulation unit 54 are provided corresponding to each ink, and four ink supply paths corresponding to each ink are independently formed. In this way, the liquid ejection device 50 of this embodiment is provided with an ink supply system to which ink is supplied from the ink tank 2 provided outside the liquid ejection head 1. Note that the liquid ejection device 50 of this embodiment is not provided with an ink recovery system that recovers the ink in the liquid ejection head 1 to the ink tank 2. Therefore, the liquid ejection head 1 is provided with a liquid connector insertion port 53a for connecting an ink supply tube 59 of the ink tank 2, but is not provided with a connector insertion port for connecting a tube for recovering ink from the liquid ejection head 1 to the ink tank 2. A liquid connector insertion port 53a is provided for each ink.

[0076] 14, the circulation unit 54 includes a circulation unit 54B for black ink, a circulation unit 54C for cyan ink, a circulation unit 54M for magenta ink, and a circulation unit 54Y for yellow ink. The circulation units 54 that circulate the reaction liquid, white ink, and other color inks have substantially the same configuration, and in the present embodiment, when there is no particular distinction between the circulation units 54, the reference characters indicating the colors, etc. may be omitted.

[0077] 13 and 14(a), the discharge unit 3 includes two discharge modules 300, a first support member 4, a second support member 7, an electric wiring member (electric wiring tape) 5, and an electric contact substrate 6. As shown in FIG. 14(b), the discharge module 300 includes a silicon substrate 310 having a thickness of 0.5 to 1 mm, and a plurality of discharge elements 15 provided on one side of the silicon substrate 310. In this embodiment, the discharge elements 15 are configured by electrothermal conversion elements (heaters) that generate thermal energy as discharge energy for discharging liquid. Each of the discharge elements 15 is supplied with power via electric wiring formed on the silicon substrate 310 by a film formation technique.

[0078] Further, a nozzle plate 320 is formed on the surface of the silicon substrate 310 (the lower surface in FIG. 14(b)). In the nozzle plate 320, a plurality of pressure chambers 12 corresponding to a plurality of ejection elements 15 and a plurality of ejection ports 13 for ejecting ink are formed by photolithography. Furthermore, a common supply flow path 18 and a common recovery flow path 19 are formed in the silicon substrate 310. Further, in the silicon substrate 310, a supply connection flow path 323 that communicates the common supply flow path 18 with each pressure chamber 12, and a recovery connection flow path 324 that communicates the common recovery flow path 19 with each pressure chamber 12 are formed. In this embodiment, one ejection module 300 is configured to eject two types of ink. That is, of the two ejection modules 300 shown in FIG. 14(a), the ejection module 300 located on the left side of the figure ejects black ink and cyan ink, and the ejection module 300 located on the right side of the figure ejects magenta ink and yellow ink. It should be noted that this combination is merely an example, and any combination of inks may be used. One ejection module may be configured to eject one type of ink, or may be configured to eject three or more types of ink. The two ejection modules 300 do not have to eject the same number of types of ink. One ejection module 300 may be provided, or three or more ejection modules 300 may be provided. Furthermore, in the example shown in FIG. 14, two ejection port arrays extending in the Y direction are formed for one color of ink. A pressure chamber 12, a supply connection flow path 323, and a recovery connection flow path 324 are respectively formed for each of the multiple ejection ports 13 that constitute each ejection port array. It has been made.

[0079] A plate supply port 311 and a plate recovery port 312 (described later) are formed on the back surface (upper surface in FIG. 14(b)) of the silicon substrate 310 (see FIGS. 22 and 23). The plate supply port 311 supplies ink from an ink supply flow path 48 to a plurality of common supply flow paths 18, and the plate recovery port 312 recovers ink from a plurality of common recovery flow paths 19 to an ink recovery flow path 49.

[0080] The plate supply port 311 and plate recovery port 312 referred to here refer to openings that supply and recover ink during forward ink circulation, which will be described later. That is, during forward ink circulation, ink is supplied from the plate supply port 311 to each of the common supply flow paths 18, and ink is recovered from each of the common recovery flow paths 19 to the plate recovery port 312. On the other hand, there are also cases where ink circulation is performed in which ink flows in the reverse direction. In this case, ink is supplied from the plate recovery port 312 described above to the common recovery flow path 19, and ink is recovered from the common supply flow path 18 to the plate supply port 311.

[0081] As shown in FIG. 14(a), the back surface (upper surface in FIG. 14(a)) of the ejection module 300 is adhesively fixed to one surface (lower surface in FIG. 14(a)) of the first support member 4. An ink supply flow path 48 and an ink recovery flow path 49 are formed in the first support member 4, penetrating from one surface to the other surface (upper surface in FIG. 14(a)). One opening of the ink supply flow path 48 is connected to the aforementioned plate supply port 311 in the silicon substrate 310, and one opening of the ink recovery flow path 49 is connected to the aforementioned plate recovery port 312 in the silicon substrate 310. The ink supply flow path 48 and the ink recovery flow path 49 are provided independently for each type of ink.

[0082] Moreover, a second support member 7 having an opening 7a (see FIG. 13) through which the ejection module 300 is inserted is adhesively fixed to one surface of the first support member 4 (the upper surface in FIG. 14(a)). The second support member 7 holds an electrical wiring member 5 that is electrically connected to the ejection module 300. The electrical wiring member 5 is a member for applying an electrical signal to the ejection module 300 for ejecting ink. The electrical connection portion between the ejection module 300 and the electrical wiring member 5 is sealed with a sealant (not shown) and is protected from corrosion by ink and external impacts.

[0083] Furthermore, an electrical contact board 6 is thermocompression bonded to an end 5a (see FIG. 13) of the electrical wiring member 5 using an anisotropic conductive film (not shown), and the electrical wiring member 5 and the electrical contact board 6 are electrically connected. The electrical contact board 6 has an external signal input terminal (not shown) for receiving an electrical signal from the liquid ejection device 50.

[0084] Furthermore, a joint member 8 (FIG. 14(a)) is provided between the first support member 4 and the circulation unit 54. A supply port 88 and a recovery port 89 are formed in the joint member 8 for each type of ink. The supply port 88 and the recovery port 89 communicate the ink supply flow path 48 and the ink recovery flow path 49 of the first support member 4 with the flow paths formed in the circulation unit 54. In FIG. 14(a), the supply port 88B and the recovery port 89B correspond to black ink, and the supply port 88C and the recovery port 89C correspond to cyan ink. Furthermore, the supply port 88M and the recovery port 89M correspond to magenta ink, and the supply port 88Y and the recovery port 89Y correspond to yellow ink.

[0085] The openings at one end of the ink supply flow passage 48 and the ink recovery flow passage 49 of the first support member 4 have small opening areas that correspond to the plate supply port 311 and the plate recovery port 312 of the silicon substrate 310. The openings at the other end of each of the ink supply flow passage 48 and the ink recovery flow passage 49 have a shape that is enlarged to the same opening area as the large opening area of ​​the joint member 8 that is formed to match the flow passage of the circulation unit 54. By adopting such a configuration, it is possible to suppress an increase in flow passage resistance to the ink collected from each recovery flow passage. However, the shapes of the openings at one end and the other end of each of the ink supply flow passage 48 and the ink recovery flow passage 49 are not limited to the above example.

[0086] In the liquid ejection head 1 having the above-mentioned configuration, ink supplied to the circulation unit 54 passes through the supply port 88 of the joint member 8 and the ink supply flow path 48 of the first support member 4, and flows into the common supply flow path 18 from the plate supply port 311 of the ejection module 300. The ink then flows from the common supply flow path 18 into the pressure chamber 12 via the supply connection flow path 323, and a portion of the ink that has flowed into the pressure chamber 12 is ejected from the ejection port 13 by driving the ejection element 15. The remaining ink that has not been ejected passes from the pressure chamber 12 through the recovery connection flow path 324 and the common recovery flow path 19, and flows into the ink recovery flow path 49 of the first support member 4 from the plate recovery port 312. The ink that has flowed into the ink recovery flow path 49 then flows into the circulation unit 54 via the recovery port 89 of the joint member 8, and is recovered.

[0087] <Components of the circulation unit> Fig. 15 is a schematic external view of one circulation unit 54 corresponding to one type of ink applied to the liquid ejection device of this embodiment. In addition to the circulation pump 500, the circulation unit 54 preferably has a filter 110, a first pressure adjustment means 120, and a second pressure adjustment means 150. These components are connected by respective flow paths as shown in Figs. 16 and 17, and constitute a circulation path that supplies and recovers ink to and from the ejection module 300 in the liquid ejection head 1.

[0088] <Circulation path inside the liquid ejection head> FIG. 16 is a vertical cross-sectional view showing a schematic diagram of a circulation path of one type of ink (one color ink) in the liquid ejection head 1. In order to explain the circulation path more clearly, the relative positions of each component (first pressure adjustment means 120, second pressure adjustment means 150, circulation pump 500, etc.) in FIG. 16 are simplified. Therefore, the relative positions of each component are different from the configuration in FIG. 30 described later. FIG. 17 is a block diagram showing a schematic diagram of the circulation path shown in FIG. 16. As shown in FIG. 16 and FIG. 17, the first pressure adjustment means 120 includes a first valve chamber 121 and a first pressure control chamber 122. The second pressure adjustment means 150 includes a second valve chamber 151 and a second pressure control chamber 152. The first pressure adjustment means 120 is configured to have a relatively higher control pressure than the second pressure adjustment means 150. In this embodiment, the first pressure adjustment means 120 and the second pressure adjustment means 150 are used to realize circulation within a certain pressure range in the circulation path. Also, the ink is configured to flow through the pressure chamber 12 (ejection element 15) at a flow rate according to the pressure difference between the first pressure adjustment means 120 and the second pressure adjustment means 150. Below, the circulation path in the liquid ejection head 1 and the flow of ink within the circulation path will be described with reference to Figures 16 and 17. Note that the arrows in each figure indicate the direction in which the ink flows.

[0089] First, the connection state of each component in the liquid ejection head 1 will be described. An external pump 21 that sends ink contained in an ink tank 2 (FIG. 17) provided outside the liquid ejection head 1 to the liquid ejection head 1 is connected to a circulation unit 54 via an ink supply tube 59 (FIG. 1). A filter 110 is provided in an ink flow path (inflow flow path) located upstream of the circulation unit 54. An ink supply path (inflow flow path) located downstream of the filter 110 is connected to a first valve chamber 121 of a first pressure adjustment means 120. The first valve chamber 121 communicates with a first pressure control chamber 122 via a communication port 191A that can be opened and closed by a valve 190A shown in FIG. 16. The inflow flow path is a flow path that flows into the liquid ejection head 1 to supply the liquid in the ink tank 2 provided outside the liquid ejection head 1 to the pressure chamber 12. It is a road.

[0090] The first pressure control chamber 122 is connected to the supply flow path 130, the bypass flow path 160, and the pump outlet flow path 180 of the circulation pump 500. The supply flow path 130 is connected to the common supply flow path 18 via the plate supply port 311 provided in the discharge module 300. The bypass flow path 160 is connected to the second valve chamber 151 provided in the second pressure adjustment means 150. The second valve chamber 151 is connected to the second pressure control chamber 152 via a communication port 191B that is opened and closed by a valve 190B shown in FIG. 16. FIGS. 16 and 17 show an example in which one end of the bypass flow path 160 is connected to the first pressure control chamber 122 of the first pressure adjustment means 120, and the other end of the bypass flow path 160 is connected to the second valve chamber 151 of the second pressure adjustment means 150. Alternatively, one end of the bypass flow path 160 may be connected to the supply flow path 130, and the other end of the bypass flow path may be connected to the second valve chamber 151.

[0091] The second pressure control chamber 152 is connected to the recovery passage 140. The recovery passage 140 is connected to the common recovery passage 19 via the plate recovery port 312 provided in the discharge module 300. Furthermore, the second pressure control chamber 152 is connected to the circulation pump 500 via a pump inlet passage 170. The pump inlet passage 170 is connected to the second pressure control chamber via an inlet 170a.

[0092] Next, a description will be given of the flow of ink in the liquid ejection head 1 having the above configuration. As shown in Fig. 17, the ink stored in the ink tank 2 is pressurized by an external pump 21 provided in the liquid ejection device 50, and is supplied to the circulation unit 54 of the liquid ejection head 1 as a positive pressure ink flow.

[0093] The ink supplied to the circulation unit 54 passes through the filter 110 to remove foreign matter such as dust and air bubbles, and then flows into the first valve chamber 121 provided in the first pressure adjustment means 120. The ink pressure decreases due to pressure loss when passing through the filter 110, but the ink pressure at this stage is positive. The ink that has flowed into the first valve chamber 121 then passes through the communication port 191A and flows into the first pressure control chamber 122 when the valve 190A is in the open state. Due to the pressure loss when passing through the communication port 191A, the ink that has flowed into the first pressure control chamber 122 switches from positive pressure to negative pressure.

[0094] Next, the flow of ink in the circulation path will be described. The circulation pump 500 operates to pump ink sucked from the pump inlet flow path 170 on the upstream side to the pump outlet flow path 180 on the downstream side. Therefore, when the circulation pump 500 is driven, the ink supplied to the first pressure control chamber 122 flows into the supply flow path 130 and the bypass flow path 160 together with the ink sent from the pump outlet flow path 180. Note that, although details will be described later, in this embodiment, a piezoelectric diaphragm pump using a piezoelectric element attached to a diaphragm as a driving source is used as the circulation pump 500 capable of sending liquid. The piezoelectric diaphragm pump is a pump that changes the volume of the pump chamber by inputting a driving voltage to a piezoelectric element, and sends liquid by alternately moving two check valves due to pressure fluctuations.

[0095] The ink that has flowed into the supply flow channel 130 flows from the plate supply port 311 of the ejection module 300 through the common supply flow channel 18 into the pressure chamber 12, and some of the ink is ejected from the ejection port 13 by driving (heat generation) the ejection element 15. The remaining ink that has not been used for ejection flows through the pressure chamber 12, passes through the common recovery flow channel 19, and then flows into the recovery flow channel 140 connected to the ejection module 300. The ink that has flowed into the recovery flow channel 140 flows into the second pressure control chamber 152 of the second pressure adjustment means 150.

[0096] On the other hand, the ink that has flowed from the first pressure control chamber 122 into the bypass flow path 160 passes through the second valve After flowing into the chamber 151, the ink passes through the communication port 191B and flows into the second pressure control chamber 152. The ink that has flowed into the second pressure control chamber 152 via the bypass flow path 160 and the ink that has been recovered from the recovery flow path 140 are sucked into the circulation pump 500 via the pump inlet flow path 170 by driving the circulation pump 500. The ink that has been sucked into the circulation pump 500 is sent to the pump outlet flow path 180 and flows into the first pressure control chamber 122 again. Thereafter, the ink that has flowed into the second pressure control chamber 152 from the first pressure control chamber 122 via the supply flow path 130 via the ejection module 300 and the ink that has flowed into the second pressure control chamber 152 via the bypass flow path 160 flow into the circulation pump 500. The ink is then sent from the circulation pump 500 to the first pressure control chamber 122. In this manner, the ink is circulated in the circulation path.

[0097] As described above, in this embodiment, the circulation pump 500 can circulate the liquid along the circulation path formed in the liquid ejection head 1. This makes it possible to suppress thickening of the ink in the ejection module 300 and accumulation of sedimentation components of the ink color material, and makes it possible to maintain the fluidity of the ink in the ejection module 300 and the ejection characteristics at the ejection port 13 in good condition.

[0098] In addition, since the circulation path in this embodiment is configured to be completed within the liquid ejection head 1, the length of the circulation path can be significantly shortened compared to when ink is circulated between the ink tank 2 provided outside the liquid ejection head and the liquid ejection head 1. This makes it possible to circulate the ink using a small circulation pump 500.

[0099] Furthermore, the connection flow path between the liquid ejection head 1 and the ink tank 2 is configured to include only a flow path for supplying ink. In other words, a configuration is adopted in which a flow path for recovering ink from the liquid ejection head 1 to the ink tank 2 is not required. Therefore, only the ink supply tube 59 is required to connect the ink tank 2 and the liquid ejection head 1, and there is no need to provide a tube for recovering ink. Therefore, the inside of the liquid ejection device 50 can be simplified with a reduced number of tubes, and the liquid ejection device 50 as a whole can be made smaller. Furthermore, by reducing the number of tubes, it is possible to reduce the pressure fluctuation of the ink caused by the oscillation of the ink supply tube 59 accompanying the main scanning of the liquid ejection head 1. In addition, the oscillation of the ink supply tube 59 during the main scanning of the liquid ejection head 1 becomes a driving load of the carriage motor 105 that drives the carriage 60. Therefore, by reducing the number of tubes, the driving load of the carriage motor 105 is reduced, and it is possible to simplify the main scanning mechanism including the carriage motor 105 and the like. Furthermore, since it is not necessary to recover ink from the liquid ejection head to an ink tank, it is also possible to reduce the size of the external pump 21. In this way, according to this embodiment, it is possible to realize a reduction in size and cost of the liquid ejection device 50.

[0100] <Pressure Adjustment Means> FIG. 18 is a diagram showing an example of pressure adjustment means. The configuration and operation of the pressure adjustment means (first pressure adjustment means 120, second pressure adjustment means 150) built into the liquid ejection head 1 described above will be described in more detail with reference to FIG. 18. The first pressure adjustment means 120 and the second pressure adjustment means 150 have substantially the same configuration. For this reason, the first pressure adjustment means 120 will be described below as an example, and the second pressure adjustment means 150 will only be described with the reference numerals of the parts corresponding to the first pressure adjustment means in FIG. 18. In the case of the second pressure adjustment means 150, the first valve chamber 121 described below will be read as the second valve chamber 151, and the first pressure control chamber 122 will be read as the second pressure control chamber 152.

[0101] The first pressure adjustment means 120 has a first valve chamber 121 and a first pressure control chamber 122 formed in a cylindrical housing 125. The first valve chamber 121 and the first pressure control chamber 122 are The first valve chamber 121 is separated by a partition wall 123 provided in a cylindrical housing 125. However, the first valve chamber 121 is in communication with the first pressure control chamber 122 via a communication port 191 formed in the partition wall 123. The first valve chamber 121 is provided with a valve 190 that switches between communication and blocking between the first valve chamber 121 and the first pressure control chamber 122 at the communication port 191. The valve 190 is held in a position facing the communication port 191 by a valve spring 200, and has a configuration that allows the valve 190 to come into close contact with the partition wall 123 by the biasing force of the valve spring 200. When the valve 190 comes into close contact with the partition wall 123, the flow of ink through the communication port 191 is blocked. In order to increase the close contact with the partition wall 123, the contact portion of the valve 190 with the partition wall 123 is preferably formed of an elastic member. Furthermore, a valve shaft 190a protrudes from the center of the valve 190 and is inserted into the communication port 191. By pressing this valve shaft 190a against the biasing force of a valve spring 200, the valve 190 moves away from the partition wall 123, allowing ink to flow through the communication port 191. Hereinafter, the state in which the valve 190 blocks the flow of ink through the communication port 191 is referred to as the "closed state," and the state in which ink can flow through the communication port 191 is referred to as the "open state."

[0102] The opening of the cylindrical housing 125 is closed by the flexible member 230 and the pressure plate 210. The first pressure control chamber 122 is formed by the flexible member 230, the pressure plate 210, the peripheral wall of the housing 125, and the partition wall 123. The pressure plate 210 is configured to be displaceable in accordance with the displacement of the flexible member 230. The materials of the pressure plate 210 and the flexible member 230 are not particularly limited, but for example, the pressure plate 210 can be configured from a resin molded part, and the flexible member 230 can be configured from a resin film. In this case, the pressure plate 210 can be fixed to the flexible member 230 by thermal welding.

[0103] A pressure adjustment spring 220 (biasing member) is provided between the pressure plate 210 and the partition wall 123. The pressure plate 210 and the flexible member 230 are biased by the biasing force of the pressure adjustment spring 220 in a direction in which the internal volume of the first pressure control chamber 122 expands, as shown in FIG. 18(a). When the pressure in the first pressure control chamber 122 decreases, the pressure plate 210 and the flexible member 230 are displaced in a direction in which the internal volume of the first pressure control chamber 122 decreases against the pressure of the pressure adjustment spring 220. When the internal volume of the first pressure control chamber 122 decreases to a certain amount, the pressure plate 210 abuts against the valve shaft 190a of the valve 190. When the internal volume of the first pressure control chamber 122 further decreases thereafter, the valve 190 moves together with the valve shaft 190a against the biasing force of the valve spring 200, and moves away from the partition wall 123. As a result, the communication port 191 is in an open state (the state shown in FIG. 18(b)).

[0104] In this embodiment, the connection in the circulation path is set so that the pressure in the first valve chamber 121 when the communication port 191 is in the open state is higher than the pressure in the first pressure control chamber 122. As a result, when the communication port 191 is in the open state, ink flows from the first valve chamber 121 to the first pressure control chamber 122. This ink flow causes the flexible member 230 and the pressure plate 210 to be displaced in a direction in which the internal volume of the first pressure control chamber 122 increases. As a result, the pressure plate 210 moves away from the valve shaft 190a of the valve 190, and the valve 190 is brought into close contact with the partition wall 123 by the biasing force of the valve spring 200, and the communication port 191 is in the closed state (the state of FIG. 18(c)).

[0105] In this manner, in the first pressure adjustment means 120 of this embodiment, when the pressure in the first pressure control chamber 122 decreases to a certain pressure or below (for example, when the negative pressure becomes stronger), ink flows in from the first valve chamber 121 via the communication port 191. This prevents the pressure in the first pressure control chamber 122 from decreasing any further. Therefore, the pressure in the first pressure control chamber 122 is controlled to be kept within a certain range.

[0106] Next, the pressure in the first pressure control chamber 122 will be described in more detail. Consider a state in which the flexible member 230 and the pressure plate 210 are displaced in response to the pressure in the force control chamber 122, causing the pressure plate 210 to come into contact with the valve shaft 190a and open the communication port 191 (the state shown in FIG. 18(b)). At this time, the relationship of the forces acting on the pressure plate 210 is expressed by the following Equation 1. P2×S2+F2+(P1-P2)×S1+F1=0...Equation 1 Furthermore, rearranging equation 1 with respect to P2 gives equation 2. P2=-(F1+F2+P1×S1) / (S2-S1)...Equation 2 P1: Pressure (gauge pressure) of the first valve chamber 121 P2: Pressure (gauge pressure) of the first pressure control chamber 122 F1: Valve spring force 200 F2: Spring force of the pressure adjusting spring 220 S1: Pressure receiving area of ​​valve 190 S2: Pressure receiving area of ​​the pressure plate 210

[0107] Here, the spring force F1 of the valve spring 200 and the spring force F2 of the pressure adjustment spring 220 are positive (leftward in FIG. 18) in the direction pressing the valve 190 and the pressure plate 210. In addition, the pressure P1 in the first valve chamber 121 and the pressure P2 in the first pressure control chamber 122 are configured so that P1 satisfies the relationship P1≧P2.

[0108] The pressure P2 in the first pressure control chamber 122 when the communication port 191 is open is determined by formula 2, and when the communication port 191 is open, due to the relationship P1≧P2, ink flows from the first valve chamber 121 into the first pressure control chamber 122. As a result, the pressure P2 in the first pressure control chamber 122 does not decrease any further, and P2 is maintained within a certain pressure range.

[0109] On the other hand, as shown in FIG. 18(c), when the pressure plate 210 is not in contact with the valve shaft 190a and the communication port 191 is closed, the relationship of the forces acting on the pressure plate 210 is expressed by Equation 3. P3×S3+F3=0...Equation 3 Here, if we rearrange Equation 3 for P3, we get Equation 4. P3 = -F3 / S3 Equation 4 F3: The spring force of the pressure adjusting spring 220 when the pressure plate 210 and the valve shaft 190a are not in contact with each other P3: pressure (gauge pressure) in the first pressure control chamber 122 when the pressure plate 210 and the valve shaft 190a are not in contact with each other S3: The pressure-receiving area of ​​the pressure plate 210 when the pressure plate 210 and the valve 190 are not in contact with each other

[0110] Here, Fig. 18(c) shows a state in which the pressure plate 210 and the flexible member 230 are displaced to the left in the figure to their limit of displacement. The pressure P3 in the first pressure control chamber 122, the spring force F3 of the pressure adjustment spring 220, and the pressure receiving area S3 of the pressure plate 210 change according to the amount of displacement while the pressure plate 210 and the flexible member 230 are displaced to the state of Fig. 18(c). Specifically, when the pressure plate 210 and the flexible member 230 are in the right direction in Fig. 18 compared to Fig. 18(c), the pressure receiving area S3 of the pressure plate 210 becomes smaller and the spring force F3 of the pressure adjustment spring 220 becomes larger. As a result, the pressure P3 in the first pressure control chamber 122 becomes smaller according to the relationship of Equation 4. Therefore, according to formulas 2 and 4, the pressure in the first pressure control chamber 122 gradually increases (i.e., the negative pressure weakens and approaches the positive pressure) from the state shown in Fig. 18(b) to the state shown in Fig. 18(c). That is, the pressure plate 210 and the flexible member 230 gradually displace to the left from the state in which the communication port 191 is open, and the pressure in the first pressure control chamber gradually increases until the internal volume of the first pressure control chamber 122 finally reaches the limit of possible displacement. In other words, the negative pressure weakens.

[0111] <Circulation pump> Next, the configuration and operation of the circulation pump 500 built into the above-mentioned liquid ejection head 1 will be described in detail with reference to FIGS.

[0112] FIG. 19 is an external perspective view of the circulation pump 500. FIG. 19(a) is an external perspective view showing the front side of the circulation pump 500, and FIG. 19(b) is an external perspective view showing the rear side of the circulation pump 500. The outer shell of the circulation pump 500 is composed of a pump housing 505 and a cover 507 fixed to the pump housing 505. The pump housing 505 is composed of a housing body 505a and a flow path connecting member 505b adhesively fixed to the outer surface of the housing body 505a. Each of the housing body 505a and the flow path connecting member 505b is provided with a pair of through holes communicating with each other at two different positions. The pair of through holes provided at one position forms the pump supply hole 501, and the pair of through holes provided at the other position forms the pump discharge hole 502. The pump supply hole 501 is connected to a pump inlet flow path 170 which is connected to the second pressure control chamber 152, and the pump discharge hole 502 is connected to a pump outlet flow path 180 which is connected to the first pressure control chamber 122. Ink supplied from the pump supply hole 501 passes through a pump chamber 503 (see FIG. 20) which will be described later, and is discharged from the pump discharge hole 502.

[0113] FIG. 20 is a cross-sectional view of the circulating pump 500 shown in FIG. 19(a) taken along line IX-IX. A diaphragm 506 is joined to the inner surface of a pump housing 505, and a pump chamber 503 is formed between the diaphragm 506 and a recess formed on the inner surface of the pump housing 505. The pump chamber 503 communicates with a pump supply hole 501 and a pump discharge hole 502 formed in the pump housing 505. A check valve 504a is provided in the middle of the pump supply hole 501, and a check valve 504b is provided in the middle of the pump discharge hole 502. Specifically, the check valve 504a is arranged so that a part of the check valve 504a can move leftward in the figure in a space 512a formed in the middle of the pump supply hole 501. A part of the check valve 504b is arranged so that it can move rightward in the figure in a space 512b formed in the middle of the pump discharge hole 502.

[0114] When diaphragm 506 is displaced to increase the volume of pump chamber 503 and reduce the pressure in pump chamber 503, check valve 504a moves away from the opening of pump supply hole 501 in space 512a (i.e., moves to the left in the figure). When check valve 504a moves away from the opening of pump supply hole 501 in space 512a, the check valve 504a enters an open state that allows the flow of ink through pump supply hole 501. When diaphragm 506 is displaced to decrease the volume of pump chamber 503 and reduce the pressure in pump chamber 503, check valve 504a comes into close contact with the wall surface surrounding the opening of pump supply hole 501. As a result, the check valve 504a enters a closed state that blocks the flow of ink through pump supply hole 501.

[0115] On the other hand, when the pump chamber 503 is depressurized, the check valve 504b comes into close contact with the wall surface surrounding the opening of the pump housing 505 and enters a closed state in which it blocks the flow of ink through the pump discharge hole 502. When the pump chamber 503 is pressurized, the check valve 504b moves away from the opening of the pump housing 505 toward the space 512b (i.e., moves to the right in the figure), allowing the flow of ink through the pump discharge hole 502.

[0116] The material of each of the check valves 504a and 504b may be any material that can deform in response to the pressure in the pump chamber 503, and may be, for example, an elastic material such as EPDM or elastomer, or a film or thin plate such as polypropylene, but is not limited to these.

[0117] As described above, the pump chamber 503 is formed by joining the pump housing 505 and the diaphragm 506. Therefore, the pump chamber 503 is formed by the deformation of the diaphragm 506. The pressure in the pump chamber 503 changes. For example, when diaphragm 506 is displaced toward pump housing 505 (displaced to the right in the figure) and the volume of pump chamber 503 decreases, the pressure in pump chamber 503 increases. This causes check valve 504b arranged opposite pump discharge hole 502 to open, and ink is discharged from pump chamber 503. At this time, check valve 504a arranged opposite pump supply hole 501 is in close contact with the wall surface surrounding pump supply hole 501, so that backflow of ink from pump chamber 503 to pump supply hole 501 is suppressed.

[0118] Conversely, when the diaphragm 506 is displaced in the direction in which the pump chamber 503 expands, the pressure in the pump chamber 503 decreases. As a result, the check valve 504a arranged opposite the pump supply hole 501 opens, and ink is supplied to the pump chamber 503. At this time, the check valve 504b arranged at the pump discharge hole 502 comes into close contact with the wall surface surrounding the opening formed in the pump housing 505 and closes the opening. As a result, the backflow of ink from the pump discharge hole 502 to the pump chamber 503 is suppressed.

[0119] In this way, in the circulation pump 500, the diaphragm 506 deforms, changing the pressure in the pump chamber 503, thereby sucking in and discharging ink. At this time, if bubbles get into the pump chamber 503, even if the diaphragm 506 is displaced, the bubbles expand and contract, reducing the pressure change in the pump chamber 503 and decreasing the amount of liquid delivered. Therefore, the pump chamber 503 is arranged parallel to gravity to make it easier for bubbles that get into the pump chamber 503 to gather above the pump chamber 503, and the pump discharge hole 502 is arranged above the center of the pump chamber 503. This makes it possible to improve the discharge of bubbles in the pump and stabilize the flow rate.

[0120] <Ink flow inside the liquid ejection head> FIG. 21 is a diagram for explaining the flow of ink in the liquid ejection head. The circulation of ink in the liquid ejection head 1 will be explained with reference to FIG. 21. In order to more clearly explain the ink circulation path, the relative positions of each component (first pressure adjustment means 120, second pressure adjustment means 150, circulation pump 500, etc.) in FIG. 21 are simplified. Therefore, the relative positions of each component are different from the configuration in FIG. 30 described later. FIG. 21(a) is a schematic diagram showing the flow of ink when a recording operation is performed in which ink is ejected from the ejection port 13 to perform recording. The arrows in the figure indicate the flow of ink. In this embodiment, when a recording operation is performed, both the external pump 21 and the circulation pump 500 start to be driven. The external pump 21 and the circulation pump 500 may be driven regardless of the recording operation. The external pump 21 and the circulation pump 500 may not be driven in conjunction with each other, and may be driven independently.

[0121] During the recording operation, the circulation pump 500 is ON (driven), and the ink flowing out from the first pressure control chamber 122 flows into the supply flow path 130 and the bypass flow path 160. The ink that flows into the supply flow path 130 passes through the ejection module 300, and then flows into the recovery flow path 140, and is then supplied to the second pressure control chamber 152. The supply flow path 130 is connected to the first pressure control chamber 122 via an opening 250, the bypass flow path 160 is connected to the first pressure control chamber 122 via an opening 260, and the recovery flow path 140 is connected to the second pressure control chamber 152 via an opening 240.

[0122] On the other hand, the ink that has flowed from the first pressure control chamber 122 into the bypass flow path 160 passes through the second valve chamber 151 and then flows into the second pressure control chamber 152. The ink that has flowed into the second pressure control chamber 152 passes through the pump inlet flow path 170, the circulation pump 500, and the pump outlet flow path 180, and then flows back into the first pressure control chamber 122. At this time, the control pressure by the first valve chamber 121 is set higher than the control pressure of the first pressure control chamber 122 based on the relationship of the above-mentioned formula 2. Therefore, the ink in the first pressure control chamber 122 does not flow into the first valve chamber 121, but is supplied again to the ejection module 300 via the supply flow path 130. The ejection module 3 The ink that has flowed into 00 passes through the recovery flow path 140, the second pressure control chamber 152, the pump inlet flow path 170, the circulation pump 500, and the pump outlet flow path 180, and then flows back into the first pressure control chamber 122. In this manner, the ink circulation is completed within the liquid ejection head 1.

[0123] In the above ink circulation, the amount of ink circulating (flow rate) in the ejection module 300 is determined by the difference in the control pressure between the first pressure control chamber 122 and the second pressure control chamber 152. This pressure difference is set so as to be a circulation amount capable of suppressing thickening of ink near the ejection port in the ejection module 300. In addition, the ink consumed by recording is supplied from the ink tank 2 to the first pressure control chamber 122 via the filter 110 and the first valve chamber 121. The mechanism by which the consumed ink is supplied will be described in detail. By reducing the ink from the circulation path by the amount of ink consumed by recording, the pressure in the first pressure control chamber is reduced, and as a result, the ink in the first pressure control chamber 122 is also reduced. As the ink in the first pressure control chamber 122 is reduced, the internal volume of the first pressure control chamber 122 is reduced. Due to this reduction in the internal volume of the first pressure control chamber 122, the communication port 191A is opened, and ink is supplied from the first valve chamber 121 to the first pressure control chamber 122. This supplied ink experiences a pressure loss when passing through communication port 191A from first valve chamber 121, and as it flows into first pressure control chamber 122, the ink changes from a positive pressure state to a negative pressure state. As ink flows from first valve chamber 121 into first pressure control chamber 122, the pressure inside first pressure control chamber 122 increases, increasing the internal volume of first pressure control chamber 122 and closing communication port 191A. In this way, communication port 191A alternates between an open state and a closed state depending on the consumption of ink. If no ink is consumed, communication port 191A is maintained in a closed state.

[0124] FIG. 21B is a schematic diagram showing the flow of ink immediately after the recording operation is completed and the circulation pump 500 is turned off (stopped). When the recording operation is completed and the circulation pump 500 is turned off, the pressure in the first pressure control chamber 122 and the pressure in the second pressure control chamber 152 are both at the control pressure during the recording operation. Therefore, the ink moves as shown in FIG. 21B according to the pressure difference between the pressure in the first pressure control chamber 122 and the pressure in the second pressure control chamber 152. Specifically, the ink continues to flow from the first pressure control chamber 122 to the ejection module 300 via the supply flow path 130, and then to the second pressure control chamber 152 via the recovery flow path 140. The ink also continues to flow from the first pressure control chamber 122 to the second pressure control chamber 152 via the bypass flow path 160 and the second valve chamber 151.

[0125] The amount of ink that has moved from the first pressure control chamber 122 to the second pressure control chamber 152 by these ink flows is supplied to the first pressure control chamber 122 from the ink tank 2 via the filter 110 and the first valve chamber 121. Therefore, the content volume in the first pressure control chamber 122 is kept constant. From the relationship of the above-mentioned formula 2, when the content volume in the first pressure control chamber 122 is constant, the spring force F1 of the valve spring 200, the spring force F2 of the pressure adjustment spring 220, the pressure receiving area S1 of the valve 190, and the pressure receiving area S2 of the pressure plate 210 are kept constant. Therefore, the pressure in the first pressure control chamber 122 is determined according to the change in the pressure (gauge pressure) P1 in the first valve chamber 121. Therefore, when there is no change in the pressure P1 in the first valve chamber 121, the pressure P2 in the first pressure control chamber 122 is kept at the same pressure as the control pressure during the recording operation.

[0126] On the other hand, the pressure in the second pressure control chamber 152 changes over time in response to a change in the content volume accompanying the inflow of ink from the first pressure control chamber 122. Specifically, from the state of FIG. 21(b) until the communication port 191B closes and the second valve chamber 151 and the second pressure control chamber 152 are not in communication with each other as shown in FIG. 21(c), the pressure in the second pressure control chamber 152 changes according to Equation 2. Thereafter, the pressure plate 210 and the valve shaft 190a are not in contact with each other and the communication port 191B is closed. Then, as shown in FIG. 21(d), ink flows from the recovery passageway 140 into the second pressure control chamber 152. This ink inflow causes the pressure plate 210 and As the flexible member 230 is displaced, the pressure in the second pressure control chamber 152 changes in accordance with Equation 4 until the internal volume of the second pressure control chamber 152 reaches its maximum. In other words, the pressure in the second pressure control chamber 152 rises.

[0127] 21(c), no ink flow occurs from the first pressure control chamber 122 to the second pressure control chamber 152 via the bypass flow path 160 and the second valve chamber 151. Therefore, after the ink in the first pressure control chamber 122 is supplied to the ejection module 300 via the supply flow path 130, only a flow occurs to the second pressure control chamber 152 via the recovery flow path 140. As described above, the movement of ink from the first pressure control chamber 122 to the second pressure control chamber 152 occurs according to the pressure difference between the pressure in the first pressure control chamber 122 and the pressure in the second pressure control chamber 152. Therefore, when the pressure in the second pressure control chamber 152 becomes equal to the pressure in the first pressure control chamber 122, the movement of ink stops.

[0128] In addition, in a state where the pressure in the second pressure control chamber 152 is equal to the pressure in the first pressure control chamber 122, the second pressure control chamber 152 expands to a state shown in FIG. 21(d). When the second pressure control chamber 152 expands as shown in FIG. 21(d), a storage portion capable of storing ink is formed in the second pressure control chamber 152. The time required from stopping the circulation pump 500 to transition to the state shown in FIG. 21(d) is about 1 to 2 minutes, which may vary depending on the shape and size of the flow path and the properties of the ink. When the circulation pump 500 is driven from the state shown in FIG. 21(d) where ink is stored in the storage portion, the ink in the storage portion is supplied to the first pressure control chamber 122 by the circulation pump 500. As a result, the amount of ink in the first pressure control chamber 122 increases as shown in FIG. 21(e), and the flexible member 230 and the pressure plate 210 are displaced in the expansion direction. Then, when the circulation pump 500 continues to be driven, the state inside the circulation path changes as shown in FIG. 21(a).

[0129] 21(a) is an example of the ink circulation during the printing operation, but as described above, the ink may be circulated without the printing operation. Even in this case, the ink flows as shown in FIG. 21(a) to FIG. 21(e) according to the driving and stopping of the circulation pump 500.

[0130] As described above, in this embodiment, the communication port 191B in the second pressure adjustment means 150 is in an open state when the circulation pump 500 is driven to circulate the ink, and is in a closed state when the circulation of the ink stops, but this is not limited to the above example. The control pressure may be set so that the communication port 191B in the second pressure adjustment means 150 is in a closed state even when the circulation pump 500 is driven to circulate the ink. Hereinafter, the role of the bypass flow path 160 will be specifically described.

[0131] The bypass flow path 160 connecting the first pressure adjustment means 120 and the second pressure adjustment means 150 is provided to prevent the negative pressure generated in the circulation path from being affected by the discharge module 300 when the negative pressure exceeds a predetermined value. The bypass flow path 160 is also provided to supply ink to the pressure chamber 12 from both sides of the supply flow path 130 and the recovery flow path 140.

[0132] First, an example will be described in which the bypass flow path 160 is provided to prevent the negative pressure from being affected by the increased negative pressure on the ejection module 300 when it exceeds a preset value. For example, the ink characteristics (e.g., viscosity) may change due to changes in the environmental temperature. When the ink viscosity changes, the pressure loss in the circulation path also changes. For example, when the ink viscosity decreases, the pressure loss in the circulation path decreases. As a result, the flow rate of the circulation pump 500, which is driven at a constant drive rate, increases, and the flow rate through the ejection module 300 increases. On the other hand, the ejection module 300 is kept at a constant temperature by a temperature adjustment mechanism (not shown), so the viscosity of the ink in the ejection module 300 remains constant even when the environmental temperature changes. The ejection module 300 is configured to have a constant temperature. The temperature of the ink is controlled by a temperature control mechanism (not shown), and the ink is maintained at a constant temperature. While there is no change in the viscosity of the ink in the ejection module 300, the flow rate of the ink flowing through the ejection module 300 increases, and the flow resistance increases the negative pressure in the ejection module 300. In this way, if the negative pressure in the ejection module 300 becomes stronger than the default value, the meniscus of the ejection port 13 may be destroyed, and external air may be drawn into the circulation path, preventing normal ejection. Even if the meniscus is not destroyed, the negative pressure in the pressure chamber 12 may become stronger than the default, affecting ejection.

[0133] For this reason, in this embodiment, the bypass flow path 160 is formed in the circulation path. By providing the bypass flow path 160, when the negative pressure becomes stronger than a preset value, ink also flows through the bypass flow path 160, so that the pressure of the ejection module 300 can be kept constant. Therefore, for example, the communication port 191B in the second pressure adjustment means 150 may be configured with a control pressure that maintains the closed state even when the circulation pump 500 is being driven. Then, the control pressure in the second pressure adjustment means may be set so that the communication port 191 in the second pressure adjustment means 150 is in an open state when the negative pressure becomes stronger than a preset value. In other words, if the meniscus does not collapse even when the flow rate of the pump is changed due to a viscosity change such as an environmental change, or if a predetermined negative pressure is maintained, the communication port 191B may be in a closed state when the circulation pump 500 is driven.

[0134] Next, an example will be described in which the bypass flow path 160 is provided to supply ink to the pressure chamber 12 from both the supply flow path 130 and the recovery flow path 140. Pressure fluctuations in the circulation path can also be caused by the ejection operation of the ejection element 15. This is because a force that draws ink into the pressure chamber 12 is generated in association with the ejection operation.

[0135] Below, it will be explained that when high duty recording continues, the ink supplied to the pressure chamber 12 is supplied to both the supply flow path 130 side and the recovery flow path 140 side. Note that the definition of duty can change depending on various conditions, but here, the state in which one 4pl ink droplet is recorded on a 1200dpi grid is treated as 100%. High duty recording means, for example, recording at a duty of 100%.

[0136] If recording at a high duty continues, the amount of ink flowing from the pressure chamber 12 into the second pressure control chamber 152 through the recovery flow path 140 decreases. On the other hand, since the circulation pump 500 causes a constant amount of ink to flow out, the balance between the inflow and outflow in the second pressure control chamber 152 is lost, the ink in the second pressure control chamber 152 decreases, the negative pressure in the second pressure control chamber 152 becomes stronger, and the second pressure control chamber 152 shrinks. Then, as the negative pressure in the second pressure control chamber 152 becomes stronger, the inflow amount of ink flowing into the second pressure control chamber 152 through the bypass flow path 160 increases, and the second pressure control chamber 152 becomes stable with the outflow and inflow balanced. As a result, the negative pressure in the second pressure control chamber 152 becomes stronger according to the duty. Furthermore, as described above, when the circulation pump 500 is driven, in a configuration in which the communication port 191B is in a closed state, the communication port 191B opens depending on the duty, and ink flows from the bypass flow path 160 into the second pressure control chamber 152.

[0137] Then, when recording at an even higher duty is continued, the amount of ink flowing from the pressure chamber 12 into the second pressure control chamber 152 through the recovery flow passage 140 decreases, and instead the amount of ink flowing into the second pressure control chamber 152 from the communication port 191B via the bypass flow passage 160 increases. If this state progresses further, the amount of ink flowing from the pressure chamber 12 into the second pressure control chamber 152 through the recovery flow passage 140 becomes zero, and all ink flowing out to the circulation pump 500 becomes ink flowing in from the communication port 191B. If this state progresses further, then ink flows back from the second pressure control chamber 152 into the pressure chamber 12 through the recovery flow passage 140. In this state, the ink flowing out from the second pressure control chamber 152 to the circulation pump 500 and the ink flowing out to the pressure chamber 12 flow into the second pressure control chamber 152 from the communication port 191B through the bypass flow passage 160. In this case, The pressure chamber 12 is filled with ink from the supply flow passage 130 and ink from the recovery flow passage 140, and is then ejected.

[0138] Incidentally, this backflow of ink occurring when the recording duty is high is a phenomenon that occurs due to the provision of the bypass flow path 160. Also, in the above, an example has been described in which the communication port 191B in the second pressure adjustment means 150 is opened in response to the backflow of ink, but backflow of ink may also occur when the communication port 191B in the second pressure adjustment means 150 is in the open state. Also, even in a configuration that does not include the second pressure adjustment means 150, the above-mentioned backflow of ink may occur due to the provision of the bypass flow path 160.

[0139] <Configuration of the discharge unit> FIG. 22 is a schematic diagram showing a circulation path for one color of ink in the discharge unit 3 of this embodiment. FIG. 22(a) is an exploded perspective view of the discharge unit 3 seen from the first support member 4 side, and FIG. 22(b) is an exploded perspective view of the discharge unit 3 seen from the discharge module 300 side. The arrows indicated by IN and OUT in the figure indicate the flow of ink, and the flow of ink for only one color will be described, but the other colors flow in the same manner. Also, the second support member 7 and the electric wiring member 5 are omitted in FIG. 22, and are also omitted in the following description of the configuration of the discharge unit 3. Also, the first support member 4 in FIG. 22(a) shows a cross section taken along the line XI-XI in FIG. 14(a). The discharge module 300 includes a recording element substrate 340 and an aperture plate 330. FIG. 23 is a diagram showing the aperture plate 330, and FIG. 24 is a diagram showing the recording element substrate 340.

[0140] Ink is supplied to the discharge unit 3 from the circulation unit 54 via a joint member 8 (see FIG. 14). The ink path from when the ink passes through the joint member 8 until when the ink returns to the joint member 8 will be described. Note that the joint member 8 will be omitted from the following drawings.

[0141] The ejection module 300 includes a recording element substrate 340, which is a silicon substrate 310, and an aperture plate 330, and further includes a nozzle plate 320. The recording element substrate 340, the aperture plate 330, and the nozzle plate 320 are overlapped and joined so that the flow paths of the inks communicate with each other to form the ejection module 300, which is supported by a first support member 4. The ejection module 300 is supported by the first support member 4 to form an ejection unit 3. The recording element substrate 340 includes the nozzle plate 320, which includes a plurality of ejection port rows in which a plurality of ejection ports 13 are arranged in a row, and ejects a portion of the ink supplied through the ink flow path in the ejection module 300 from the ejection port 13. Ink that is not ejected is collected through the ink flow path in the ejection module 300.

[0142] As shown in FIG. 22 and FIG. 23, the opening plate 330 includes a plurality of arranged plate supply ports 311 and a plurality of arranged plate recovery ports 312. As shown in FIG. 24 and FIG. 25, the recording element substrate 340 includes a plurality of arranged supply connection channels 323 and a plurality of arranged recovery connection channels 324. The recording element substrate 340 further includes a common supply channel 18 communicating with the plurality of supply connection channels 323 and a common recovery channel 19 communicating with the plurality of recovery connection channels 324. The ink flow channels in the ejection unit 3 are formed by communicating an ink supply channel 48 and an ink recovery channel 49 (see FIG. 14) provided in the first support member 4 with a flow channel provided in the ejection module 300. The support member supply port 211 is a cross-sectional opening that forms the ink supply channel 48, and the support member recovery port 212 is a cross-sectional opening that forms the ink recovery channel 49.

[0143] The ink to be supplied to the ejection unit 3 is supplied to the ink supply flow passage 48 (see FIG. 14(a)) of the first support member 4 from the circulation unit 54 (see FIG. 14(a)). The ink that has flowed through the support member supply port 211 in the passage 48 is supplied to the common supply flow path 18 of the recording element substrate 340 via the ink supply flow path 48 (see FIG. 14(a)) and the plate supply port 311 of the opening plate 330, and enters the supply connection flow path 323. This is the supply side flow path. The ink then flows through the pressure chamber 12 of the nozzle plate 320 (see FIG. 14(b)) to the recovery connection flow path 324, which is a recovery side flow path. The flow of ink in the pressure chamber 12 will be described in detail later.

[0144] In the recovery side flow path, the ink that has entered the recovery connection flow path 324 flows into the common recovery flow path 19. After that, the ink flows from the common recovery flow path 19 through the plate recovery port 312 of the opening plate 330 to the ink recovery flow path 49 of the first support member 4, and then through the support member recovery port 212 to be recovered in the circulation unit 54.

[0145] The area of ​​the aperture plate 330 without the plate supply port 311 or the plate recovery port 312 corresponds to the area for separating the support member supply port 211 and the support member recovery port 212 in the first support member 4. Moreover, the first support member 4 also does not have an opening in this area. Such an area is used as an adhesion area when the discharge module 300 and the first support member 4 are adhered to each other.

[0146] In FIG. 23, the aperture plate 330 has a plurality of rows of apertures arranged in the X direction, and the supply (IN) apertures and the recovery (OUT) apertures are arranged alternately in the Y direction so as to be shifted by half a pitch in the X direction. In FIG. 24, the recording element substrate 340 has a common supply flow path 18 communicating with a plurality of supply connection flow paths 323 arranged in the Y direction, and a common recovery flow path 19 communicating with a plurality of recovery connection flow paths 324 arranged in the Y direction, arranged alternately in the X direction. The common supply flow paths 18 and the common recovery flow path 19 are divided according to the type of ink, and further, the number of common supply flow paths 18 and common recovery flow paths 19 is determined according to the number of ejection port rows of each color. In addition, the supply connection flow paths 323 and the recovery connection flow paths 324 are also arranged in the number corresponding to the ejection ports 13. It is not necessarily required that there is a one-to-one correspondence, and one supply connection flow path 323 and one recovery connection flow path 324 may correspond to a plurality of ejection ports 13.

[0147] Such an aperture plate 330 and a recording element substrate 340 are overlapped and joined so that the flow paths of each ink are connected to form an ejection module 300, and by being supported by a first support member 4, an ink flow path is formed that has the above-mentioned supply flow path and recovery flow path.

[0148] Fig. 25(a) to Fig. 25(c) are cross-sectional views showing ink flows in different parts of the discharge unit 3. Fig. 25(a) is a cross-section taken along line XIVa-XIVa in Fig. 22(a) and shows a cross-section of a part where the ink supply flow path 48 and the plate supply port 311 in the discharge unit 3 communicate with each other. Fig. 25(b) is a cross-section taken along line XIVb-XIVb in Fig. 22(a) and shows a cross-section of a part where the ink recovery flow path 49 and the plate recovery port 312 in the discharge unit 3 communicate with each other. Fig. 25(c) is a cross-section taken along line XIVc-XIVc in Fig. 22(a) and shows a cross-section of a part where the plate supply port 311 and the plate recovery port 312 do not communicate with the flow path of the first support member 4.

[0149] In the supply flow path that supplies ink, as shown in FIG. 25(a), ink is supplied from a portion where the ink supply flow path 48 of the first support member 4 and the plate supply port 311 of the aperture plate 330 overlap and communicate with each other. In the recovery flow path that recovers ink, as shown in FIG. 25(b), ink is recovered from a portion where the ink recovery flow path 49 of the first support member 4 and the plate recovery port 312 of the aperture plate 330 overlap and communicate with each other. Also, as shown in FIG. 25(c), in the ejection unit 3, there are some regions where the aperture plate 330 does not have any openings. In such regions, ink is not supplied or recovered between the recording element substrate 340 and the first support member 4. Ink is supplied in the region where the plate supply port 311 is provided as shown in FIG. 25(a), and ink is not recovered from the region where the plate supply port 311 is provided as shown in FIG. As shown in FIG. 25(b), ink is recovered in an area where a plate recovery port 312 is provided. In the present embodiment, the opening plate 330 is used as an example, but a configuration may be adopted in which the opening plate 330 is not used. For example, a configuration may be adopted in which flow paths corresponding to the ink supply flow path 48 and the ink recovery flow path 49 are formed in the first support member 4, and the recording element substrate 340 is joined to the first support member 4.

[0150] 26(a) and 26(b) are cross-sectional views showing the vicinity of the ejection port 13 in the ejection module 300, and FIG. 27(a) and FIG. 27(b) are cross-sectional views showing an ejection module having a configuration in which the common supply flow path 18 and the common recovery flow path 19 are widened in the X direction as a comparative example. Note that the thick arrows shown in the common supply flow path 18 and the common recovery flow path 19 in FIG. 26 and FIG. 27 indicate the oscillation of ink in a configuration in which a serial type liquid ejection device 50 is used. The ink supplied to the pressure chamber 12 via the common supply flow path 18 and the supply connection flow path 323 is ejected from the ejection port 13 by driving the ejection element 15. When the ejection element 15 is not driven, the ink is recovered from the pressure chamber 12 to the common recovery flow path 19 via the recovery connection flow path 324, which is a recovery flow path.

[0151] In the case of using the serial type liquid ejection device 50, when ejecting from the circulating ink, the ejection of the ink is influenced by the ink oscillation in the ink flow path caused by the main scanning of the liquid ejection head 1. Specifically, the influence of the ink oscillation in the ink flow path may appear as a difference in the amount of ink ejected or a deviation in the ejection direction. As shown in FIG. 27, when the common supply flow path 18 and the common recovery flow path 19 have a cross-sectional shape that is wide in the X direction, which is the main scanning direction, the ink in the common supply flow path 18 and the common recovery flow path 19 is easily subjected to an inertial force in the main scanning direction, and the ink is greatly oscillated. As a result, there is a risk that the ink oscillation will affect the ejection of the ink from the ejection port 13. In addition, if the common supply flow path 18 and the common recovery flow path 19 are widened in the X direction, the distance between the colors will be increased, which may reduce the printing efficiency.

[0152] Therefore, the common supply flow path 18 and the common recovery flow path 19 of this embodiment extend in the Y direction in the cross section shown in FIG. 26, but are also configured to extend in the Z direction perpendicular to the X direction, which is the main scanning direction. With this configuration, the width of each flow path in the main scanning direction of the common supply flow path 18 and the common recovery flow path 19 can be reduced. By reducing the width of each flow path in the main scanning direction of the common supply flow path 18 and the common recovery flow path 19, the ink oscillation caused by the inertial force (indicated by the thick black arrow in the figure) acting on the ink in the common supply flow path 18 and the common recovery flow path 19 in the opposite direction to the main scanning direction during the main scanning is reduced. This makes it possible to suppress the effect of the ink oscillation on the ink ejection. In addition, the cross-sectional area is increased by extending the common supply flow path 18 and the common recovery flow path 19 in the Z direction, thereby reducing the flow path pressure loss.

[0153] As described above, by reducing the width of each of the common supply flow path 18 and the common recovery flow path 19 in the main scanning direction, the oscillation of ink in the common supply flow path 18 and the common recovery flow path 19 during main scanning is reduced, but the oscillation is not eliminated. Therefore, in order to suppress the occurrence of differences in ejection for each ink type that may still occur even with the reduced oscillation, in this embodiment, the common supply flow path 18 and the common recovery flow path 19 are configured to be disposed at positions that overlap with each other in the X direction.

[0154] As described above, in this embodiment, the supply connection flow path 323 and the recovery connection flow path 324 are provided corresponding to the discharge port 13, and the supply connection flow path 323 and the recovery connection flow path 324 are arranged side by side in the X direction with the discharge port 13 in between. If there is a portion where the common supply flow path 18 and the common recovery flow path 19 do not overlap in the Y direction, the corresponding relationship between the supply connection flow path 323 and the recovery connection flow path 324 in the X direction will be lost. In that case, If the ink fluctuation has an effect on the ink flow and ejection in the X direction, the ink ejection from each ejection port 13 may be further affected.

[0155] In contrast to this, in the embodiment, the common supply flow path 18 and the common recovery flow path 19 are arranged at positions where they overlap in the Y direction. Therefore, at any position in the Y direction where the ejection ports 13 are arranged, the ink oscillation during main scanning in the common supply flow path 18 and the common recovery flow path 19 is approximately the same. As a result, the pressure difference between the common supply flow path 18 side and the common recovery flow path 19 side generated in the pressure chamber 12 does not vary greatly, and stable ejection can be performed.

[0156] In addition, in some liquid ejection heads that circulate ink, the flow path that supplies ink to the liquid ejection head and the flow path that recovers ink are configured as the same flow path, but in this embodiment, the common supply flow path 18 and the common recovery flow path 19 are configured as separate flow paths. The supply connection flow path 323 and the pressure chamber 12 are connected to each other, and the pressure chamber 12 and the recovery connection flow path 324 are connected to each other, and ink is ejected from the ejection port 13 of the pressure chamber 12. In other words, the pressure chamber 12, which is a path that connects the supply connection flow path 323 and the recovery connection flow path 324, is configured to have the ejection port 13. Therefore, an ink flow that flows from the supply connection flow path 323 side to the recovery connection flow path 324 side is generated in the pressure chamber 12, and the ink in the pressure chamber 12 is efficiently circulated. By efficiently circulating the ink in the pressure chamber 12, the ink in the pressure chamber 12, which is easily affected by the evaporation of ink from the ejection port 13, can be kept fresh.

[0157] Furthermore, since the two flow paths, the common supply flow path 18 and the common recovery flow path 19, are connected to the pressure chamber 12, if it becomes necessary to eject ink at a high flow rate, it is possible to supply ink from both flow paths. In other words, compared to a configuration in which ink supply and recovery are configured using only one flow path, the configuration of this embodiment has the advantage of not only being able to circulate ink efficiently, but also being able to handle ejection at a high flow rate.

[0158] Furthermore, the common supply flow path 18 and the common recovery flow path 19 are less susceptible to the influence of ink fluctuations when they are disposed close to each other in the X direction. It is preferable that the distance between the flow paths is 75 μm to 100 μm.

[0159] FIG. 28 is a diagram showing a recording element substrate 340 as a comparative example. In FIG. 28, the supply connection flow path 323 and the recovery connection flow path 324 are omitted. Since ink that has received thermal energy from the ejection elements 15 in the pressure chambers 12 flows into the common recovery flow path 19, ink with a relatively high temperature flows in comparison with the temperature of the ink in the common supply flow path 18. At this time, in the comparative example, there is a portion in the Y direction of the recording element substrate 340 where only the common recovery flow path 19 exists, as in the α portion surrounded by the dashed line in FIG. 28. In other words, the common supply flow path 18 and the common recovery flow path 19 do not overlap at least partially in the Y direction. In this case, the temperature increases locally in that portion, causing temperature unevenness in the ejection module 300, which may affect ejection.

[0160] In the common supply flow path 18, ink flows that is at a relatively low temperature relative to the common recovery flow path 19. Therefore, when the common supply flow path 18 and the common recovery flow path 19 are adjacent to each other, the temperatures in the common supply flow path 18 and the common recovery flow path 19 are partially offset in the vicinity thereof, suppressing a temperature rise. Therefore, it is preferable that the common supply flow path 18 and the common recovery flow path 19 have approximately the same length in the Y direction, are positioned so as to overlap each other over approximately the entire area in the Y direction, and are adjacent to each other.

[0161] 29(a) and 29(b) are diagrams showing the flow path configuration of the liquid ejection head 1 corresponding to three colors of ink, cyan (C), magenta (M), and yellow (Y). As shown in FIG. 29(a), the liquid ejection head 1 is provided with circulation flow paths for each type of ink. are provided along the X direction which is the main scanning direction of the liquid ejection head 1. Also, as shown in Fig. 29(b), the common supply flow path 18 and the common recovery flow path 19 are provided along the ejection port row in which the ejection ports 13 are arranged, and are provided extending in the Y direction so as to sandwich the ejection port row between the common supply flow path 18 and the common recovery flow path 19.

[0162] <Connection between the main body and the liquid ejection head> 30 is a schematic diagram showing in more detail the connection state between the ink tank 2 and external pump 21 provided in the main body of the liquid ejection device 50 of this embodiment and the liquid ejection head 1, and the arrangement of the circulation pump 500, etc. The liquid ejection device 50 of this embodiment has a configuration that allows the liquid ejection head 1 alone to be easily replaced when a malfunction occurs in the liquid ejection head 1. Specifically, it has a liquid connection part 700 that allows the ink supply tube 59 connected to the external pump 21 to be easily connected and disconnected from the liquid ejection head 1. This makes it possible to easily attach and detach only the liquid ejection head 1 to and from the liquid ejection device 50.

[0163] 30, the liquid connection part 700 has a liquid connector insertion port 53a protruding from the head housing 53 of the liquid ejection head 1, and a cylindrical liquid connector 59a into which the liquid connector insertion port 53a can be inserted. The liquid connector insertion port 53a is fluidly connected to an ink supply flow path (inflow flow path) formed in the liquid ejection head 1, and is connected to the first pressure adjustment means 120 via the above-mentioned filter 110. In addition, the liquid connector 59a is provided at the tip of an ink supply tube 59 connected to an external pump 21 that pressurizes and supplies ink from the ink tank 2 to the liquid ejection head 1.

[0164] As described above, the liquid ejection head 1 shown in Fig. 30 allows easy attachment, detachment, and replacement of the liquid ejection head 1 by the liquid connection part 700. However, if the sealing performance between the liquid connector insertion port 53a and the liquid connector 59a deteriorates, there is a risk that ink supplied under pressure by the external pump 21 will leak from the liquid connection part 700. If the leaked ink adheres to the circulation pump 500 or the like, a malfunction may occur in the electrical system. Therefore, in this embodiment, the circulation pump and the like are arranged as follows.

[0165] <Location of circulating pumps, etc.> As shown in FIG. 30, in this embodiment, in order to prevent ink leaking from the liquid connection part 700 from adhering to the circulation pump 500, the circulation pump 500 is disposed above the liquid connection part 700 in the direction of gravity. That is, the circulation pump 500 is disposed above the liquid connector insertion port 53a, which is the liquid inlet port of the liquid ejection head 1, in the direction of gravity. Furthermore, the circulation pump 500 is disposed at a position where it is not in contact with the members constituting the liquid connection part 700. As a result, even if ink leaks from the liquid connection part 700, the ink flows in the horizontal direction, which is the opening direction of the liquid connector 59a, or downward in the direction of gravity, so that it is possible to prevent the ink from reaching the circulation pump 500, which is located above in the direction of gravity. In addition, since the circulation pump 500 is disposed at a position away from the liquid connection part 700, the possibility that the ink will reach the circulation pump 500 by running down the members is also reduced.

[0166] Furthermore, the electrical connection part 515, which electrically connects the circulation pump 500 and the electrical contact board 6 via a flexible wiring member 514, is provided above the liquid connection part 700 in the direction of gravity. This makes it possible to reduce the possibility of electrical trouble caused by ink from the liquid connection part 700.

[0167] Furthermore, in this embodiment, since the wall portion 53b of the head housing 53 is provided, even if ink is ejected from the opening 59b of the liquid connection portion 700, the ink can be blocked, reducing the possibility of the ink reaching the circulation pump 500 or the electrical connection portion 515.

[0168] The disclosure of this embodiment includes the following configurations and methods. (Configuration 1) A head unit of an inkjet recording device having a plurality of heads each having a nozzle array formed with a plurality of nozzles for ejecting liquid, the head unit performing recording by ejecting liquid while moving back and forth in a main scanning direction onto a recording medium, The plurality of heads include a first head in which a nozzle row is formed to eject a reaction liquid that reacts with at least one of the color ink and the white ink; a second head in which a nozzle row for ejecting the color inks and a nozzle row for ejecting the white ink are formed; Including, The first head and the second head are the nozzle row for the reaction liquid is located at a position closest to a first end, which is one end of the head unit in the main scanning direction, and the nozzle row for the white ink is located at a position closest to a second end, which is the other end of the head unit in the main scanning direction; The head units are arranged in line along the main scanning direction. (Configuration 2) The head unit according to configuration 1, wherein the first head has a nozzle row for the reaction liquid for the white ink and a nozzle row for the reaction liquid for the color inks formed therein. (Configuration 3) the second head is disposed closer to the second end than the first head, a nozzle row for the white ink reaction liquid is formed in the first head at a position closest to the first end portion; 3. The head unit according to configuration 2, wherein in the second head, a nozzle row for the white ink is formed at a position closest to the second end portion. (Configuration 4) A head unit of an inkjet recording device having a plurality of heads each having a nozzle array formed with a plurality of nozzles for ejecting liquid, the head unit performing recording by ejecting liquid while moving back and forth in a main scanning direction onto a recording medium, The plurality of heads include a first head in which a nozzle row is formed to eject a reaction liquid that reacts with at least one of the color ink and the white ink; a second head in which a nozzle row for ejecting the color ink is formed; a third head in which a nozzle row for ejecting the white ink is formed; Including, The first head, the second head, and the third head are the nozzle row for the reaction liquid is located at a position closest to a first end, which is one end of the head unit in the main scanning direction, and the nozzle row for the white ink is located at a position closest to a second end, which is the other end of the head unit in the main scanning direction; The head units are arranged in line along the main scanning direction. (Configuration 5) The head unit according to configuration 4, wherein the first head has a nozzle row for the reaction liquid for the white ink and a nozzle row for the reaction liquid for the color inks formed therein. (Configuration 6) the third head is formed with a nozzle row for the white ink and a nozzle row for the color inks, The head unit according to configuration 5, wherein in the third head, a nozzle row for the white ink is formed at a position closest to the second end portion. (Configuration 7) The third head further includes a nozzle row for gray ink. A head unit according to configuration 6, wherein in the third head, the nozzle row of the gray ink is formed adjacent to the nozzle row of the white ink on a side closer to the first end than the nozzle row of the white ink. (Configuration 8) the second head is disposed closer to the second end than the first head, the third head is disposed closer to the second end than the second head, a nozzle row for the white ink reaction liquid is formed in the first head at a position closest to the first end portion; The head unit according to configuration 6 or 7, wherein in the third head, a nozzle row for the white ink is formed at a position closest to the second end portion. (Configuration 9) A head unit of an inkjet recording device having a plurality of heads each having a nozzle array formed with a plurality of nozzles for ejecting liquid, the head unit performing recording by ejecting liquid while moving back and forth in a main scanning direction onto a recording medium, The plurality of heads include a first head in which a nozzle row for ejecting a reaction liquid that reacts with at least one of the color inks and the white ink and a nozzle row for ejecting the white ink are formed; a second head in which a nozzle row for ejecting the color ink is formed; a third head in which a nozzle row for ejecting the reaction liquid and a nozzle row for ejecting the white ink are formed; Including, The first head, the second head, and the third head are the nozzle row for the reaction liquid is located at a position closest to a first end, which is one end of the head unit in the main scanning direction, and the nozzle row for the reaction liquid is located at a position closest to a second end, which is the other end of the head unit in the main scanning direction; The head units are arranged in line along the main scanning direction. (Configuration 10) the first head is formed with a nozzle row for the white ink reaction liquid, a nozzle row for the color ink reaction liquid, and a nozzle row for the white ink; 10. The head unit according to configuration 9, wherein the third head includes a nozzle row for the reaction liquid for the white ink, a nozzle row for the reaction liquid for the color inks, and a nozzle row for the white ink. (Configuration 11) the first head is formed with a nozzle row for the white ink reaction liquid, a nozzle row for the white ink, and a nozzle row for the color ink reaction liquid in this order from the side closest to the first end portion, A head unit described in configuration 10, wherein the third head has a nozzle row for the reaction liquid for the white ink, a nozzle row for the white ink, and a nozzle row for the reaction liquid for the color inks formed in this order from the side closest to the second end. (Configuration 12) For each of the color inks, the white ink, and the reaction liquid, 12. The head unit according to any one of configurations 1 to 11, further comprising a circulation device that supplies liquid to the nozzles, recovers liquid that has not been ejected from the nozzles, and supplies the liquid to the nozzles again. (Configuration 13) 13. The head unit according to configuration 12, wherein the liquid is supplied to the circulation device from a tank provided in a main body of the inkjet recording device. (Configuration 14) A head unit according to any one of configurations 1 to 3, a carriage on which the head unit is mounted; a driving means for reciprocating the carriage in the main scanning direction; An inkjet recording apparatus comprising: Within a range in which recording is performed on the recording medium, an end portion closer to the first end portion in the main scanning direction is defined as a third end portion, and an end portion closer to the second end portion is defined as a fourth end portion, In a print mode in which recording is performed using only the color inks, The driving means is when the carriage is moved in a direction toward the first end portion, the carriage is moved to a position where a nozzle row of a color ink adjacent to the nozzle row of the white ink of the second head passes through the third end portion; An inkjet recording device characterized in that, when the carriage is moved in a direction toward the second end, the nozzle row of the color ink closest to the first end of the second head is moved to a position passing through the fourth end. (Configuration 15) A head unit according to any one of configurations 1 to 3, a carriage on which the head unit is mounted; a driving means for reciprocating the carriage in the main scanning direction; An inkjet recording apparatus comprising: Within a range in which recording is performed on the recording medium, an end portion closer to the first end portion in the main scanning direction is defined as a third end portion, and an end portion closer to the second end portion is defined as a fourth end portion, In a print mode in which recording is performed using only the color inks and the white ink, The driving means is when the carriage is moved in a direction toward the first end portion, the carriage is moved to a position where the nozzle row of the white ink of the second head passes through the third end portion; An inkjet recording device characterized in that, when the carriage is moved in a direction toward the second end, the nozzle row of the color ink closest to the first end of the second head is moved to a position passing through the fourth end. (Configuration 16) A head unit according to configuration 3; a carriage on which the head unit is mounted; a driving means for reciprocating the carriage in the main scanning direction; An inkjet recording apparatus comprising: Within a range in which recording is performed on the recording medium, an end portion closer to the first end portion in the main scanning direction is defined as a third end portion, and an end portion closer to the second end portion is defined as a fourth end portion, In a print mode in which recording is performed using only the color inks and the reaction liquid for the color inks, The driving means is when moving the carriage in a direction toward the first end portion, moving the carriage to a position where a nozzle row of a color ink adjacent to the nozzle row of the white ink of the second head passes through the third end portion; an inkjet recording device, characterized in that when the carriage is moved in a direction toward the second end, the carriage is moved to a position where a nozzle row for the reaction liquid for the color ink of the first head passes through the fourth end. (Configuration 17) A head unit according to any one of configurations 6 to 8, a carriage on which the head unit is mounted; a driving means for reciprocating the carriage in the main scanning direction; An inkjet recording apparatus comprising: Within a range in which recording is performed on the recording medium, an end portion closer to the first end portion in the main scanning direction is defined as a third end portion, and an end portion closer to the second end portion is defined as a fourth end portion, In a print mode in which recording is performed using only the color inks, The driving means is when moving the carriage in a direction toward the first end portion, moving the carriage to a position where a nozzle row of a color ink adjacent to the nozzle row of the white ink of the third head passes through the third end portion; An inkjet recording device characterized in that, when the carriage is moved in a direction toward the second end, the nozzle row of the color ink closest to the first end of the second head is moved to a position passing through the fourth end. (Configuration 18) A head unit according to any one of configurations 4 to 8, a carriage on which the head unit is mounted; a driving means for reciprocating the carriage in the main scanning direction; An inkjet recording apparatus comprising: Within a range in which recording is performed on the recording medium, an end portion closer to the first end portion in the main scanning direction is defined as a third end portion, and an end portion closer to the second end portion is defined as a fourth end portion, In a print mode in which recording is performed using only the color inks and the white ink, The driving means is when the carriage is moved in a direction toward the first end portion, the carriage is moved to a position where the nozzle row of the white ink of the third head passes through the third end portion; An inkjet recording device characterized in that, when the carriage is moved in a direction toward the second end, the nozzle row of the color ink closest to the first end of the second head is moved to a position passing through the fourth end. (Configuration 19) A head unit according to configuration 8; a carriage on which the head unit is mounted; a driving means for reciprocating the carriage in the main scanning direction; An inkjet recording apparatus comprising: Within a range in which recording is performed on the recording medium, an end portion closer to the first end portion in the main scanning direction is defined as a third end portion, and an end portion closer to the second end portion is defined as a fourth end portion, In a print mode in which recording is performed using only the color inks and the reaction liquid for the color inks, The driving means is when moving the carriage in a direction toward the first end portion, moving the carriage to a position where a nozzle row of a color ink adjacent to the nozzle row of the white ink of the third head passes through the third end portion; an inkjet recording device, characterized in that when the carriage is moved in a direction toward the second end, the carriage is moved to a position where a nozzle row for the reaction liquid for the color ink of the first head passes through the fourth end. (Configuration 20) A head unit according to any one of configurations 9 to 11, a carriage on which the head unit is mounted; a driving means for reciprocating the carriage in the main scanning direction; An inkjet recording apparatus comprising: Within a range in which recording is performed on the recording medium, an end portion closer to the first end portion in the main scanning direction is defined as a third end portion, and an end portion closer to the second end portion is defined as a fourth end portion, In a print mode in which recording is performed using only the color inks, The driving means is when the carriage is moved in a direction toward the first end, the carriage is moved to a position where a nozzle row of the color ink of the second head that is closest to the second end passes through the third end, When the carriage is moved in a direction toward the second end, the front of the second head an ink jet recording apparatus, comprising: a nozzle row for a color ink, the nozzle row being located closest to the first end portion, being moved to a position passing through the fourth end portion; (Configuration 21) A head unit according to any one of configurations 9 to 11, a carriage on which the head unit is mounted; a driving means for reciprocating the carriage in the main scanning direction; An inkjet recording apparatus comprising: Within a range in which recording is performed on the recording medium, an end portion closer to the first end portion in the main scanning direction is defined as a third end portion, and an end portion closer to the second end portion is defined as a fourth end portion, In a print mode in which recording is performed using only the color inks and the white ink, The driving means is when the carriage is moved in a direction toward the first end portion, the carriage is moved to a position where the nozzle row of the white ink of the third head passes through the third end portion; an inkjet recording apparatus, wherein when the carriage is moved in a direction toward the second end, the carriage is moved to a position where the nozzle row of the white ink of the first head passes through the fourth end; (Configuration 22) A head unit according to configuration 11, a carriage on which the head unit is mounted; a driving means for reciprocating the carriage in the main scanning direction; An inkjet recording apparatus comprising: Within a range in which recording is performed on the recording medium, an end portion closer to the first end portion in the main scanning direction is defined as a third end portion, and an end portion closer to the second end portion is defined as a fourth end portion, In a print mode in which recording is performed using only the color inks and the reaction liquid for the color inks, The driving means is when the carriage is moved in a direction toward the first end portion, the carriage is moved to a position where a nozzle row for the reaction liquid for the color ink of the third head passes through the third end portion; an inkjet recording device, characterized in that when the carriage is moved in a direction toward the second end, the carriage is moved to a position where a nozzle row for the reaction liquid for the color ink of the first head passes through the fourth end. [Explanation of symbols]

[0169] 10: head unit, 1: liquid ejection head, 1a: first head, 1b: second head, 1c: third head, 10a: first end, 10b: second end, 50: liquid ejection device, 331: ejection port, 332: nozzle row, S: recording sheet

Claims

1. A head unit for an inkjet recording apparatus having multiple heads each having a nozzle row consisting of multiple nozzles for ejecting liquid, and performing recording by ejecting liquid while reciprocating in the main scanning direction relative to a recording medium, The aforementioned multiple heads are A first head is formed with a first nozzle row that discharges a reaction solution for white ink that reacts with white ink, and a second nozzle row that discharges a reaction solution for color ink that reacts with color ink, A second head having a nozzle row for ejecting the aforementioned color ink and a nozzle row for ejecting the aforementioned white ink, Includes, The first head and the second head are The first nozzle row or the second nozzle row is positioned closest to the first end, which is one end of the main scanning direction in the head unit, and the white ink nozzle row is positioned closest to the second end, which is the other end. A head unit characterized by being arranged in a line along the main scanning direction.

2. The second head is positioned on the side closer to the second end of the first head, In the first head, the first nozzle row is formed at the position closest to the first end. The head unit according to claim 1, wherein the nozzle row for the white ink is formed at the position closest to the second end of the second head.

3. A head unit for an inkjet recording apparatus having multiple heads each having a nozzle row consisting of multiple nozzles for ejecting liquid, and performing recording by ejecting liquid while reciprocating in the main scanning direction relative to a recording medium, The aforementioned multiple heads are A first head is formed with a first nozzle row that discharges a reaction solution for white ink that reacts with white ink, and a second nozzle row that discharges a reaction solution for color ink that reacts with color ink, A second head having a row of nozzles for ejecting the aforementioned color ink, A third head having a row of nozzles for ejecting the aforementioned white ink, Includes, The first head, the second head, and the third head are The first nozzle row or the second nozzle row is positioned closest to the first end, which is one end of the main scanning direction in the head unit, and the white ink nozzle row is positioned closest to the second end, which is the other end. A head unit characterized by being arranged in a line along the main scanning direction.

4. The third head has a row of nozzles for the white ink and a row of nozzles for the color ink. The head unit according to claim 3, wherein the row of white ink nozzles is formed in the third head at the position closest to the second end.

5. The third head further has a row of gray ink nozzles formed therein. The head unit according to claim 4, wherein in the third head, the row of gray ink nozzles is formed adjacent to the row of white ink nozzles, on the side closer to the first end, relative to the row of white ink nozzles.

6. The second head is positioned on the side closer to the second end of the first head, The third head is positioned on the side closer to the second end of the second head, In the first head, the first nozzle row is formed at the position closest to the first end. The head unit according to claim 4 or 5, wherein the nozzle row of the white ink is formed at the position closest to the second end of the third head.

7. A head unit for an inkjet recording apparatus having multiple heads each having a nozzle row consisting of multiple nozzles for ejecting liquid, and performing recording by ejecting liquid while reciprocating in the main scanning direction relative to a recording medium, The aforementioned multiple heads are A first head having a nozzle row for dispensing a reaction solution that reacts with at least one of a color ink and a white ink, and a nozzle row for dispensing white ink, A second head having a row of nozzles for ejecting the aforementioned color ink, A third head having a row of nozzles for discharging the reaction solution and a row of nozzles for discharging the white ink, Includes, The first head, the second head, and the third head are The nozzle row of the reaction solution is positioned closest to the first end, which is one end of the main scanning direction in the head unit, and the nozzle row of the reaction solution is positioned closest to the second end, which is the other end. A head unit characterized by being arranged in a line along the main scanning direction.

8. The first head has a nozzle row for the reaction solution for the white ink, a nozzle row for the reaction solution for the color ink, and a nozzle row for the white ink. The head unit according to claim 7, wherein the third head has a nozzle row for the reaction solution for the white ink, a nozzle row for the reaction solution for the color ink, and a nozzle row for the white ink.

9. The first head has a row of nozzles for the reaction solution for the white ink, a row of nozzles for the white ink, and a row of nozzles for the reaction solution for the color ink, arranged in this order from the side closest to the first end. It is formed in The head unit according to claim 8, wherein the third head has a row of nozzles for the reaction solution for the white ink, a row of nozzles for the white ink, and a row of nozzles for the reaction solution for the color ink, formed in this order from the side closest to the second end.

10. Regarding each of the liquids in the aforementioned color ink, white ink, and reaction solution, The head unit according to any one of claims 1 to 5, 7 to 9, further comprising a circulation device that supplies liquid to the nozzle, recovers the liquid that was not discharged from the nozzle, and supplies it back to the nozzle.

11. The head unit according to claim 10, wherein the liquid is supplied to the circulation device from a tank provided in the main body of the inkjet recording device.

12. The head unit according to claim 1 or 2, A carriage on which the aforementioned head unit is mounted, A drive means for reciprocating the carriage in the main scanning direction, An inkjet recording device having, Within the recording area of ​​the recording medium, the end closer to the first end in the main scanning direction is defined as the third end, and the end closer to the second end is defined as the fourth end. In a printing mode that records using only the aforementioned color inks, The aforementioned driving means is When moving the carriage toward the first end, move it to a position where the nozzle row of color ink adjacent to the nozzle row of white ink of the second head passes the third end. An inkjet recording apparatus characterized in that, when moving the carriage toward the second end, the second head is moved to a position where the nozzle row of color ink closest to the first end passes the fourth end.

13. The head unit according to claim 1 or 2, A carriage on which the aforementioned head unit is mounted, A drive means for moving the carriage back and forth in the main scanning direction, An inkjet recording device having, Within the recording area of ​​the recording medium, the end closer to the first end in the main scanning direction is defined as the third end, and the end closer to the second end is defined as the fourth end. In a printing mode that records using only the aforementioned color ink and the aforementioned white ink, The aforementioned driving means is When moving the carriage toward the first end, move it to a position where the row of white ink nozzles of the second head passes the third end. An inkjet recording apparatus characterized in that, when moving the carriage toward the second end, the second head is moved to a position where the nozzle row of color ink closest to the first end passes the fourth end.

14. The head unit according to claim 2, A carriage on which the aforementioned head unit is mounted, A drive means for moving the carriage back and forth in the main scanning direction, An inkjet recording device having, Within the recording area of ​​the recording medium, the end closer to the first end in the main scanning direction is defined as the third end, and the end closer to the second end is defined as the fourth end. In a printing mode in which recording is performed using only the aforementioned color ink and the reaction solution for the color ink, The aforementioned driving means is When moving the carriage toward the first end, move it to a position where the nozzle row of color ink adjacent to the nozzle row of white ink of the second head passes the third end. An inkjet recording apparatus characterized in that, when moving the carriage toward the second end, the carriage is moved to a position where the second nozzle row of the reaction solution for the color ink of the first head passes the fourth end.

15. The head unit according to claim 4 or 5, A carriage on which the aforementioned head unit is mounted, A drive means for moving the carriage back and forth in the main scanning direction, An inkjet recording device having, Within the recording area of ​​the recording medium, the end closer to the first end in the main scanning direction is defined as the third end, and the end closer to the second end is defined as the fourth end. In a printing mode that records using only the aforementioned color inks, The aforementioned driving means is When moving the carriage toward the first end, move it to a position where the nozzle row of color ink adjacent to the nozzle row of white ink of the third head passes the third end. An inkjet recording apparatus characterized in that, when moving the carriage toward the second end, the second head is moved to a position where the nozzle row of color ink closest to the first end passes the fourth end.

16. A head unit according to any one of claims 3 to 5, A carriage on which the aforementioned head unit is mounted, A drive means for moving the carriage back and forth in the main scanning direction, An inkjet recording device having, Within the recording area of ​​the recording medium, the end closer to the first end in the main scanning direction is defined as the third end, and the end closer to the second end is defined as the fourth end. In a printing mode that records using only the aforementioned color ink and the aforementioned white ink, The aforementioned driving means is When moving the carriage toward the first end, move it to a position where the row of white ink nozzles of the third head passes the third end. An inkjet recording apparatus characterized in that, when moving the carriage toward the second end, the second head is moved to a position where the nozzle row of color ink closest to the first end passes the fourth end.

17. The head unit according to claim 6, A carriage on which the aforementioned head unit is mounted, A drive means for moving the carriage back and forth in the main scanning direction, An inkjet recording device having, Within the recording area of ​​the recording medium, the end closer to the first end in the main scanning direction is defined as the third end, and the end closer to the second end is defined as the fourth end. In a printing mode in which recording is performed using only the aforementioned color ink and the reaction solution for the color ink, The aforementioned driving means is When moving the carriage toward the first end, move it to a position where the nozzle row of color ink adjacent to the nozzle row of white ink of the third head passes the third end. When moving the carriage toward the second end, in front of the first head An inkjet recording apparatus characterized by moving the second nozzle row to a position where it passes the fourth end.

18. A head unit according to any one of claims 7 to 9, A carriage on which the aforementioned head unit is mounted, A drive means for moving the carriage back and forth in the main scanning direction, An inkjet recording device having, Within the recording area of ​​the recording medium, the end closer to the first end in the main scanning direction is defined as the third end, and the end closer to the second end is defined as the fourth end. In a printing mode that records using only the aforementioned color inks, The aforementioned driving means is When moving the carriage toward the first end, move it to a position where the nozzle row of color ink closest to the second end of the second head passes the third end. An inkjet recording apparatus characterized in that, when moving the carriage toward the second end, the second head is moved to a position where the nozzle row of color ink closest to the first end passes the fourth end.

19. A head unit according to any one of claims 7 to 9, A carriage on which the aforementioned head unit is mounted, A drive means for moving the carriage back and forth in the main scanning direction, An inkjet recording device having, Within the recording area of ​​the recording medium, the end closer to the first end in the main scanning direction is defined as the third end, and the end closer to the second end is defined as the fourth end. In a printing mode that records using only the aforementioned color ink and the aforementioned white ink, The aforementioned driving means is When moving the carriage toward the first end, move it to a position where the row of white ink nozzles of the third head passes the third end. An inkjet recording apparatus characterized in that, when moving the carriage toward the second end, the carriage is moved to a position where the row of white ink nozzles of the first head passes the fourth end.

20. The head unit according to claim 9, A carriage on which the aforementioned head unit is mounted, A drive means for moving the carriage back and forth in the main scanning direction, An inkjet recording device having, Within the recording area of ​​the recording medium, the end closer to the first end in the main scanning direction is defined as the third end, and the end closer to the second end is defined as the fourth end. In a printing mode in which recording is performed using only the aforementioned color ink and the reaction solution for the color ink, The aforementioned driving means is When moving the carriage toward the first end, move it to a position where the nozzle row of the reaction solution for the color ink of the third head passes the third end. An inkjet recording apparatus characterized in that, when moving the carriage toward the second end, the carriage is moved to a position where the nozzle row of the reaction solution for the color ink of the first head passes the fourth end.