Inkjet head, method of manufacturing the inkjet head, and inkjet recording apparatus

Abstract

An inkjet head, the inkjet head having: a silicon nozzle substrate (11) having an ink flow path surface (S1) and an ink ejection surface (S2) facing the flow path surface (S1), and having a nozzle (111) penetrating from the flow path surface (S1) to the ejection surface (S2); a flow path substrate (12) joined to the ink flow path surface (S1) of the silicon nozzle substrate (11) and including an ink flow path and a substrate main body (12a) having a formation surface of the flow path; and a liquid-repellent film (14) provided on the ejection surface (S2) of the silicon nozzle substrate (11), wherein the flow path substrate (12) has: a through-flow path (125) penetrating the substrate main body (12a) so as to face the nozzle (111); and n individual circulation flow paths (121) communicating with the through-flow path (125) and extending in a direction away from the nozzle (111), and having a portion overlapping the substrate main body (12a) when viewed from above in a plan view from the side opposite to the surface of the flow path substrate (12) joined to the silicon nozzle substrate (11), and the positional relationship between each individual circulation flow path (121) and the nozzle (111) has a specific relationship.

Description

Technical Field

[0001] The present invention relates to an inkjet head, a method for manufacturing the inkjet head, and an inkjet recording apparatus. Background Art

[0002] For the nozzle substrate and the flow path substrate of an inkjet head, a silicon processing technique is applied to ensure processing accuracy. In particular, in a structure having a circulation flow path, a process of processing and bonding a silicon nozzle substrate and a flow path substrate having a circulation flow path is performed. However, from the viewpoint of flow path design, the silicon nozzle substrate sometimes has a substrate thickness of 100 μm or less, and the processing during manufacturing becomes difficult. Therefore, sometimes the following method is adopted: a nozzle is formed on a silicon substrate having a support layer, and after bonding to the flow path substrate, the support layer is removed, thereby manufacturing an inkjet head chip in which the silicon nozzle substrate and the flow path substrate are integrated.

[0003] On the other hand, on the ejection surface of the silicon nozzle substrate, a liquid-repellent film is formed to stabilize the ejection direction of ink droplets and improve ejection performance.

[0004] In the embodiment shown in Patent Document 1, a manufacturing method of forming a liquid-repellent film after bonding the nozzle substrate and the flow path substrate is shown. However, since the liquid-repellent film is also formed in the flow path, it is conceivable that the wettability is reduced and ejection failure occurs. In order to remove the liquid-repellent film, generally a process of removing it by oxygen plasma treatment or the like is adopted. However, in the flow path structure shown in Patent Document 1, particularly in a structure having a circulation flow path in the upper part of the nozzle, oxygen ions or oxygen radicals often cannot reach the flow path and cannot be removed.

[0005] In addition, Patent Document 2 shows a method of forming a liquid-repellent film on the nozzle substrate after nozzle processing and then bonding it to the flow path substrate. However, there is a concern that the liquid-repellent film may accidentally spread to the bonding surface side of the nozzle substrate during the manufacturing process. In particular, when an adhesive is used for bonding the nozzle substrate and the flow path substrate, when the removal process of the liquid-repellent film by oxygen plasma treatment is insufficient, the reliability of the bonding portion is reduced. Therefore, it is preferable to form the liquid-repellent film after bonding the nozzle substrate and the flow path substrate.

[0006] In the process of forming a liquid-repellent film on the ejection surface of the silicon nozzle substrate after bonding the silicon nozzle substrate and the circulation flow path substrate, it is required to form the liquid-repellent film only on the ejection surface side of the silicon nozzle substrate.

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: Japanese Patent No. 5645863 Gazette

[0010] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2006-256223 Gazette Summary of the Invention

[0011] Problems to be Solved by the Invention

[0012] The present invention has been made in view of the above problems and circumstances, and the problem to be solved is to provide an inkjet head with excellent ink ejection performance, a method for manufacturing the inkjet head, and an inkjet recording apparatus.

[0013] Means for Solving the Problems

[0014] In order to solve the above problems, the inventors of the present invention found in the process of studying the causes of the above problems that by setting the positional relationship between the nozzles of the silicon nozzle substrate and the circulation flow paths of the flow path substrate to a relationship that satisfies specific conditions, an inkjet head in which the formation of a liquid-repellent film in the flow path substrate is suppressed can be obtained. The inkjet head includes a silicon nozzle substrate and a flow path substrate having a circulation flow path, and thus the present invention has been completed. That is, the above problems of the present invention are solved by the following means.

[0015] 1. An inkjet head, the inkjet head having:

[0016] A silicon nozzle substrate having an ink flow surface and an ink ejection surface facing the flow surface, and having nozzles penetrating from the flow surface to the ejection surface;

[0017] A flow path substrate joined to the flow surface of the silicon nozzle substrate, and including an ink flow path and a substrate body forming the flow path; and

[0018] A liquid-repellent film provided on the ejection surface of the silicon nozzle substrate,

[0019] wherein,

[0020] The flow path substrate has a through-flow path and n individual circulation flow paths as the ink flow paths. The through-flow path penetrates the substrate body facing the nozzles. The n individual circulation flow paths communicate with the through-flow path and extend in a direction away from the nozzles, and the n individual circulation flow paths have portions overlapping the substrate body when viewed from above on the side opposite to the surface of the flow path substrate joined to the silicon nozzle substrate,

[0021] The positional relationship between each of the individual circulation flow paths and the nozzles satisfies the following formula 1:

[0022] L×tanφ>H1 Formula 1

[0023] Each symbol in Formula 1 has the following meanings in a cross-section obtained by cutting the silicon nozzle substrate and the flow path substrate with a plane orthogonal to the flow path surface of the silicon nozzle substrate in such a way as to include the center of the nozzle and the separate circulation flow path:

[0024] φ: The angle formed by the straight line connecting the first nozzle end on the side of the ejection surface away from the separate circulation flow path and the second nozzle end on the side of the flow path surface close to the separate circulation flow path with the ejection surface

[0025] L: The distance from the straight line passing through the first nozzle end and orthogonal to the ejection surface to the intersection point of the formation surface of the through-flow path and the formation surface of the separate circulation flow path in the substrate body that is farthest from the flow path surface

[0026] H1: The distance from the ejection surface to the intersection point of the formation surface of the through-flow path and the formation surface of the separate circulation flow path in the substrate body that is farthest from the flow path surface.

[0027] 2. The inkjet head according to the first item, wherein the inkjet head has a structure in which the diameter of the nozzle gradually decreases from the flow path surface toward the ejection surface, and the φ in Formula 1 is the maximum angle among the angles formed by the straight line connecting the first nozzle end and the end on the side of each section close to the separate circulation flow path on the flow path surface with the ejection surface.

[0028] 3. The inkjet head according to the first or second item, wherein at least two of the separate circulation flow paths are located on a straight line passing through the center of the nozzle on the flow path surface,

[0029] the centers of the nozzle and the through-flow path coincide, and in a cross-section obtained by cutting with a plane orthogonal to the flow path surface of the silicon nozzle substrate in such a way as to include the centers of the nozzle and the through-flow path and the two separate circulation flow paths, the two separate circulation flow paths are in a symmetric relationship,

[0030] the positional relationship among the separate circulation flow path, the through-flow path, and the nozzle satisfies the following Formula 2:

[0031] (W - D2) / (D1 + D2) × t > H2 Formula 2

[0032] D1: The diameter of the nozzle on the ejection surface

[0033] D2: The diameter of the nozzle on the flow path surface

[0034] t: The thickness of the silicon nozzle substrate

[0035] H2: The distance from the flow path surface to the intersection point of the formation surface of the through-flow path in the substrate main body and the formation surface of the individual circulation flow path, which is the intersection point farthest from the flow path surface.

[0036] W: The width of the through-flow path.

[0037] 4. The inkjet head according to any one of the first to third items, wherein the liquid-repellent film is formed by vapor deposition.

[0038] 5. The inkjet head according to any one of the first to fourth items, wherein the silicon nozzle substrate and the flow path substrate are joined by an adhesive.

[0039] 6. The inkjet head according to any one of the first to fifth items, wherein the liquid-repellent film is composed of a base layer containing a silicon compound and a fluoropolymer layer sequentially provided from the side of the silicon nozzle substrate.

[0040] 7. The inkjet head according to any one of the first to sixth items, wherein the thickness of the silicon nozzle substrate is in the range of 10 to 100 μm.

[0041] 8. A method for manufacturing an inkjet head, which manufactures the inkjet head according to any one of the first to seventh items, wherein the method for manufacturing the inkjet head includes:

[0042] The first step, in which the flow path substrate is joined to the flow path surface of the silicon nozzle substrate in the first step;

[0043] The second step, after the first step, in which a vapor deposition source of the liquid-repellent film is arranged on the ejection surface side of the silicon nozzle substrate joined to the flow path substrate and the liquid-repellent film is formed by vapor deposition; and

[0044] The third step, after the second step, in which the liquid-repellent film on the formation surface of the through-flow path formed in the substrate main body is removed from the side of the flow path substrate in the third step.

[0045] 9. The method for manufacturing an inkjet head according to the eighth item, wherein in the removal of the liquid-repellent film, UV ozone irradiation or oxygen plasma irradiation is performed from the side of the flow path substrate to the formation surface of the through-flow path of the substrate main body.

[0046] 10. An inkjet recording apparatus including the inkjet head according to any one of the first to seventh items.

[0047] Effects of the invention

[0048] According to the above solution of the present invention, an inkjet head and a method for manufacturing an inkjet head can be provided. In an inkjet head having a silicon nozzle substrate with a liquid-repellent film on the ejection surface side and a flow path substrate having a circulation flow path, the formation of the liquid-repellent film into the flow path substrate is suppressed, whereby the ink ejection performance is excellent. In the method for manufacturing an inkjet head, the situation where the liquid-repellent film is formed in the flow path substrate during manufacturing is suppressed. In addition, an inkjet recording apparatus including an inkjet head with excellent ink ejection performance can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 FIG. is a schematic diagram showing an example of an embodiment of the inkjet recording apparatus of the present invention.

[0050] Figure 2 is Figure 1 a bottom view of an example of the head unit of the inkjet recording apparatus shown in FIG.

[0051] Figure 3 FIG. is a perspective view showing an example of an embodiment of the inkjet head of the present invention.

[0052] Figure 4 is Figure 3 a cross-sectional view in the left-right direction of the lower part of the inkjet head shown in FIG.

[0053] Figure 5 is Figure 3 an exploded perspective view of the inkjet head shown in FIG.

[0054] Figure 6 FIG. is an enlarged top view of the nozzle periphery showing an example of a laminate of a liquid-repellent film, a silicon nozzle substrate, and a flow path substrate as viewed from the flow path substrate side.

[0055] Figure 7 FIG. is a cross-sectional view taken along VII-VII of Figure 6 the laminate shown in FIG.

[0056] Figure 8A FIG. is a cross-sectional view of an example of a shear mode type inkjet head chip using Figure 6 , 7 the laminate shown in FIG.

[0057] Figure 8B FIG. is a cross-sectional view of an example of an embodiment of a bending mode type inkjet head chip.

[0058] Figure 9A FIG. is a cross-sectional view of a modified example of a laminate of a liquid-repellent film, a silicon nozzle substrate, and a flow path substrate.

[0059] Figure 9B FIG. is a cross-sectional view of a modified example of a laminate of a liquid-repellent film, a silicon nozzle substrate, and a flow path substrate.

[0060] Figure 10 An enlarged top view of the periphery of the nozzle showing a modified example of the stack of the liquid-repellent film, the silicon nozzle substrate, and the flow path substrate as viewed from the side of the flow path substrate.

[0061] Figure 11 Is a cross-sectional view taken along XI-XI Figure 10 Of the stack shown.

[0062] Figure 12 Is Figure 1 A bottom view of another example of the head unit of the inkjet recording apparatus shown.

[0063] Figure 13 Is a component of Figure 12 An exploded perspective view of the inkjet head chip of the inkjet head that constitutes the head unit shown.

[0064] Figure 14A Is Figure 13 A top view of the pressure chamber substrate of the inkjet head chip shown.

[0065] Figure 14B Is Figure 13 A bottom view of the pressure chamber substrate of the inkjet head chip shown.

[0066] Figure 15A Is Figure 13 A top view of the flow path substrate of the inkjet head chip shown.

[0067] Figure 15B Is Figure 13 A bottom view of the flow path substrate of the inkjet head chip shown.

[0068] Figure 16 Is Figure 13 A top view of the silicon nozzle substrate of the inkjet head chip shown.

[0069] Figure 17A Is a cross-sectional view taken along XVIIA-XVIIA Figure 13 Of the inkjet head chip shown.

[0070] Figure 17B Is a cross-sectional view taken along XVIIB-XVIIB Figure 13 Of the inkjet head chip shown.

[0071] Figure 18A Is a cross-sectional view taken along XVIIIA-XVIIIA Figure 13 Of the inkjet head chip shown.

[0072] Figure 18B Is a cross-sectional view taken along XVIIIB-XVIIIB Figure 13 Of the inkjet head chip shown.

[0073] Figure 19 It is a schematic diagram showing an ink circulation system.

[0074] Figure 20 It is a cross-sectional view after the first process in an example of the manufacturing method of the inkjet head of the present invention.

[0075] Figure 21 It is a cross-sectional view after the second process in an example of the manufacturing method of the inkjet head of the present invention.

[0076] Figure 22 It is a cross-sectional view after the third process in an example of the manufacturing method of the inkjet head of the present invention. Detailed Embodiments

[0077] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the scope of the invention is not limited to the illustrated examples. It should be noted that, in this specification, for the sake of convenience of explanation, the direction in which the following recording medium M is conveyed is defined as the front-rear direction, the direction orthogonal to the direction in which the recording medium M is conveyed on the printing surface of the recording medium M, that is, the printing width direction of the inkjet head 100 is defined as the left-right direction, and the thickness direction of the recording medium M is defined as the up-down direction for explanation. In addition, the arrows in the flow paths of the drawings indicate the flow direction of the ink.

[0078] The inkjet head of the present invention is used by being mounted on an inkjet recording apparatus. Figure 3 It is a perspective view showing an example of an embodiment of the inkjet head of the present invention, Figure 4 and Figure 5 is Figure 3 a left-right direction cross-sectional view of the lower part of the inkjet head 100 shown and an exploded perspective view of the inkjet head 100. Figure 1 For example, it is mounted with Figure 3 a schematic diagram of an inkjet recording apparatus 200 equipped with the inkjet head 100 of the present invention shown, Figure 2 is Figure 1 a bottom view of the head unit of the inkjet recording apparatus 200 shown.

[0079] [Inkjet Recording Apparatus]

[0080] Figure 1 The inkjet recording apparatus 200 shown includes a paper feeding unit 210, an image recording unit 220, a paper discharging unit 230, and an ink circulation system (refer to Figure 19 ) as an ink supply member, etc. The inkjet recording apparatus 200 conveys the recording medium M stored in the paper feeding unit 210 to the image recording unit 220, forms an image on the recording medium M using the image recording unit 220, and conveys the recording medium M with the formed image to the paper discharging unit 230.

[0081] The paper supply unit 210 includes a paper supply tray 211 for storing the recording medium M and a medium supply unit 212 for conveying and supplying the recording medium M from the paper supply tray 211 to the image recording unit 220. The medium supply unit 212 includes an annular belt supported by two rollers on the inner side, and rotates the rollers while the recording medium M is placed on the belt, thereby conveying the recording medium M from the paper supply tray 211 to the image recording unit 220.

[0082] The image recording unit 220 includes a conveyance drum 221, a transfer unit 222, a heating unit 223, a head unit 224, a fixing unit 225, a conveyance unit 226, etc.

[0083] The conveyance drum 221 has a cylindrical surface, and its outer peripheral surface serves as a conveyance surface for placing the recording medium M. The conveyance drum 221 rotates in the direction of the arrow in Figure 1 while holding the recording medium M on its conveyance surface, thereby conveying the recording medium M along the conveyance surface. In addition, the conveyance drum 221 includes a claw portion and a suction portion (not shown), presses the end portion of the recording medium M by the claw portion, and attracts the recording medium M to the conveyance surface by the suction portion, thereby holding the recording medium M on the conveyance surface.

[0084] The transfer unit 222 is provided at a position between the medium supply unit 212 of the paper supply unit 210 and the conveyance drum 221, holds and picks up one end of the recording medium M conveyed from the medium supply unit 212 by the swing arm portion 222a, and transfers it to the conveyance drum 221 via the transfer drum 222b.

[0085] The heating unit 223 is provided between the arrangement position of the transfer drum 222b and the arrangement position of the head unit 224, and heats the recording medium M so that the recording medium M conveyed by the conveyance drum 221 becomes a temperature within a specified temperature range. The heating unit 223 has, for example, an infrared heater, etc., and energizes the infrared heater based on a control signal supplied from a control unit (not shown) to make the heater generate heat.

[0086] The head unit 224 has a rectangular ink ejection surface with the long side direction in the direction orthogonal to the feeding direction of the recording medium M (left - right direction), and the ink ejection surface is arranged facing the conveyance drum 221 with a specified distance therebetween. The length of the ink ejection surface of the head unit 224 in the long side direction corresponds to the printing width of the recording medium M.

[0087] The head unit 224 ejects ink onto the recording medium M at an appropriate timing corresponding to the rotation of the conveyance drum 221 holding the recording medium M based on the image data, thereby forming an image. In the inkjet recording apparatus 200 of the present embodiment, for example, four head units 224 corresponding to inks of four colors, namely yellow (Y), magenta (M), cyan (C), and black (K), are arranged at prescribed intervals in the color order of Y, M, C, K from the upstream side in the conveyance direction of the recording medium M.

[0088] The head unit 224, for example, as Figure 2 shown, a pair of groups of inkjet heads 100 adjacent in the front-rear direction are arranged in a staggered manner at different positions in the front-rear direction. The inkjet head 100 has a rectangular ink ejection surface with the left-right direction being the long side direction, and on the ink ejection surface, a plurality of nozzles 111 are arranged at substantially equal intervals along the left-right direction. A liquid-repellent film 14 is formed on the ink ejection surface.

[0089] In addition, the position of the head unit 224 relative to the rotation axis of the conveyance drum 221 is fixed during image recording and used. That is, the inkjet recording apparatus 200 is an inkjet recording apparatus 200 that performs image recording using a single-pass (one-pass) drawing method with a line head.

[0090] The fixing unit 225 has a light-emitting unit arranged over the width of the conveyance drum 221 in the X direction, and irradiates energy rays such as ultraviolet rays from the light-emitting unit onto the recording medium M placed on the conveyance drum 221 to cure and fix the ink ejected onto the recording medium M. The light-emitting unit of the fixing unit 225 is arranged on the downstream side of the arrangement position of the head unit 224 and on the upstream side of the arrangement position of the transfer drum 226a of the conveying unit 226 in the conveyance direction, facing the conveyance surface.

[0091] The conveying unit 226 includes: a belt loop 226b having an annular belt supported by two rollers on the inner side; and a cylindrical transfer drum 226a that transfers the recording medium M from the conveyance drum 221 to the belt loop 226b, and conveys the recording medium M transferred from the conveyance drum 221 to the belt loop 226b by the belt loop 226b and sends it out to the paper discharge unit 230.

[0092] The paper discharge unit 230 has a plate-shaped paper discharge tray 231 on which the printed recording medium PM sent out from the image recording unit 220 by the conveying unit 226 is placed.

[0093] [Inkjet head]

[0094] As Figure 3 , Figure 4 and Figure 5As shown in the figure, the inkjet head 100 of the present embodiment includes: an inkjet head chip 1; a wiring substrate 2 provided with the inkjet head chip 1; a drive circuit substrate 4 connected to the wiring substrate 2 via a flexible substrate 3; a manifold 5 for storing ink supplied to the inkjet head chip 1; a housing 6 for accommodating the manifold 5 inside; a cover receiving plate 7 installed to block the bottom opening of the housing 6; and a cover member 9 installed on the housing 6, etc. It should be noted that in Figure 3 the illustration of the manifold 5 is omitted, and in Figure 4 and Figure 5 the illustration of the cover member 9 is omitted.

[0095] The inkjet head chip 1 is a substantially quadrangular prism-shaped component that is long in the left-right direction, and is formed by sequentially laminating a pressure chamber substrate 13, a flow path substrate 12, a silicon nozzle substrate 11, and a liquid-repellent film 14 from the manifold 5 side. Regarding the inkjet head chip 1, it will be described in detail later. Here, the schematic structure of the inkjet head 100 will be described below. Figures 6 to 18B It will be described in detail later. Here, the schematic structure of the inkjet head 100 will be described below.

[0096] The silicon nozzle substrate 11 is a plate-like body mainly made of silicon (Si), and has nozzles 111 penetrating between the two main surfaces. The main surface of the silicon nozzle substrate 11 on the side opposite to the flow path substrate 12 constitutes the ink ejection surface. A liquid-repellent film 14 is formed on the ink ejection surface of the silicon nozzle substrate 11.

[0097] The flow path substrate 12 has a substrate main body for forming the ink flow path and the ink flow path formed by the substrate main body. The flow path substrate 12 has, as the ink flow path: at least a through-flow path that penetrates the substrate main body and is located at a position facing the nozzles 111; and a separate circulation flow path provided to circulate the ink in the inkjet recording apparatus 200.

[0098] The pressure chamber substrate 13 includes a mechanism for applying pressure to the ink so as to eject the ink supplied from the manifold 5 to the inkjet head chip 1 through the flow path substrate 12 from the nozzles 111 of the silicon nozzle substrate toward the recording medium M. The pressure applying mechanism can be a shear mode type or a bending mode type. The pressure chamber substrate 13 has, for example, a supply flow path for supplying ink from the manifold 5 to the flow path substrate 12 and a common circulation flow path communicating with the separate circulation flow path of the flow path substrate 12.

[0099] The ink supplied to the inkjet head chip 1 is pressurized and a part of it is ejected from the nozzles 111, and the remaining part is discharged from the inkjet head chip 1 via the separate circulation flow path and the common circulation flow path. The ink discharged from the inkjet head chip 1 is supplied to the inkjet head chip 1 again through the ink circulation system (refer to Figure 19 ).

[0100] As shown in Figure 5As shown, a wiring substrate 2 is disposed on the upper surface of the inkjet head chip 1 , and two flexible substrates 3 connected to a driving circuit substrate 4 are disposed on both edges of the wiring substrate 2 along the front-rear direction.

[0101] The wiring substrate 2 is formed in a substantially rectangular plate shape that is long in the horizontal direction and has an opening 22 substantially in the center thereof. The wiring substrate 2 is formed to have a width greater than that of the inkjet head chip 1 in the horizontal direction and the front-rear direction.

[0102] The opening 22 is formed in a substantially rectangular shape that is long in the left-right direction, and when the inkjet head chip 1 is mounted on the wiring substrate 2, the inlet of the ink supply flow path and the outlet of the common circulation flow path of the pressure chamber substrate 13 in the inkjet head chip 1 are opened, for example, Figure 13 The inlet of each supply flow path 131 and the outlet of the second common circulation flow path 135 in the inkjet head chip 1 are exposed upward. It should be noted that in this specification, the "inlet" of the ink flow path refers to the upstream end, and the "outlet" refers to the downstream end.

[0103] The flexible substrate 3 electrically connects the driving circuit substrate 4 and the electrode portion of the wiring substrate 2 , and can apply a signal from the driving circuit substrate 4 to the driving electrode provided on the partition wall 136 in the inkjet head chip 1 via the flexible substrate 3 .

[0104] The lower end of the manifold 5 is fixed by bonding to the outer edge of the wiring substrate 2. That is, the manifold 5 is disposed above the pressure chamber substrate 13 of the inkjet head chip 1 and connected to the inkjet head chip 1 via the wiring substrate 2.

[0105] The manifold 5 is a component formed of resin, and is disposed on the upper portion of the pressure chamber substrate 13 of the inkjet head chip 1 to store ink supplied to the inkjet head chip 1. Figure 4 As shown in the figures, the manifold 5 is formed long in the left-right direction and includes a hollow main body 52 constituting an ink storage portion 51 and first to fourth ink ports 53 to 56 constituting an ink flow path. In addition, the ink storage portion 51 is divided into two liquid chambers, a first liquid chamber 51a on the upper side and a second liquid chamber 51b on the lower side, by a filter F for removing debris in the ink.

[0106] The first ink port 53 is connected to the upper right end of the first liquid chamber 51a and is used to introduce ink into the ink storage unit 51. In addition, a first joint 81a is externally inserted into the front end of the first ink port 53. The second ink port 54 is connected to the upper left end of the first liquid chamber 51a and is used to remove bubbles in the first liquid chamber 51a.

[0107] In addition, a second connector 81b is externally inserted at the front end of the second ink port 54. The third ink port 55 communicates with the upper left end of the second liquid chamber 51b and is used to remove air bubbles in the second liquid chamber 51b. In addition, a third connector 82a is externally inserted at the front end of the third ink port 55. The fourth ink port 56 communicates with the discharge liquid chamber 57 that is connected to the outlet of the common circulation path of the inkjet head chip 1, and the ink discharged from the inkjet head chip 1 is discharged to the outside of the inkjet head 100 through the fourth ink port 56.

[0108] The housing 6 is a component formed by die-casting using aluminum as a material and is formed in a long strip shape in the left-right direction. In addition, the housing 6 is formed so as to be able to accommodate the manifold 5 in which the inkjet head chip 1, the wiring substrate 2, and the flexible substrate 3 are installed inside, and the bottom surface of the housing 6 is open. In addition, mounting holes 68 for mounting the housing 6 to the printer main body side are respectively formed at both ends in the left-right direction of the housing 6.

[0109] The nozzle receiving plate 7 is formed with a nozzle opening 71 that is long in the left-right direction at its substantially central portion, and is mounted so that the nozzle substrate 11 is exposed through the nozzle opening 71 to block the bottom opening of the housing 6.

[0110] In the inkjet head 100 of the present embodiment, the inkjet head chip 1 has features. In the inkjet head chip 1, in particular, the laminated structure of the flow path substrate 12, the silicon nozzle substrate 11, and the liquid-repellent film 14 has features. Hereinafter, with reference to Figures 6 to 11 , the laminate of the flow path substrate 12, the silicon nozzle substrate 11, and the liquid-repellent film 14 in the inkjet head chip 1 will be described.

[0111] Figure 6 is a magnified top view of the periphery of the nozzle 111 of the laminate 10A, which is an example of the laminate of the flow path substrate 12, the silicon nozzle substrate 11, and the liquid-repellent film 14 in the inkjet head 100 as viewed from the side of the flow path substrate 12, Figure 2 as shown, Figure 7 is a cross-sectional view obtained by cutting the laminate 10A along VII-VII, Figure 6 as shown. Figure 8A is a cross-sectional view of an example of a shear mode type inkjet head chip using the laminate 10A, Figure 6 , Figure 7 as shown. Figure 8B represents a cross-sectional view of an example of an embodiment of a bending mode type inkjet head chip of a laminate of a flow path substrate 12, a silicon nozzle substrate 11, and a liquid-repellent film 14, which uses a structure different from that of the laminate 10A, particularly a different structure of the flow path substrate 12. Figure 8B The laminate shown as Figure 2 is also the laminate used in the inkjet head 100 shown as

[0112] The laminate 10A includes: a silicon nozzle substrate 11 having an ink flow path surface S1 and an ink ejection surface S2 facing the flow path surface S1, and having nozzles 111 penetrating from the flow path surface S1 to the ejection surface S2; a flow path substrate 12 joined to the flow path surface S1 of the silicon nozzle substrate 11, having an ink flow path and a substrate main body 12a having a formation surface of the flow path; and a liquid-repellent film 14 disposed on the ejection surface S2 of the silicon nozzle substrate 11.

[0113] As Figure 2 shown, a plurality of nozzles 111 are provided in the silicon nozzle substrate 11 that is substantially rectangular in plan view. The nozzles 111 are formed to be arranged in a row along the long side direction (left-right direction) of the silicon nozzle substrate 11 and are located substantially at the center in the short side direction (front-back direction). The nozzles 111 are in the shape of an inverted truncated cone, and are formed such that the diameter on the flow path surface S1 side is larger than the diameter on the ejection surface S2 side in plan view.

[0114] The diameter of the nozzles 111 is appropriately adjusted according to the specifications of the inkjet head 100. The diameter of the nozzles 111 can be set to be approximately 20 to 200 μm on the flow path surface S1 side and approximately 10 to 100 μm on the ejection surface S2 side in plan view. As Figure 7 shown, the angle φ used in Equation 1 is determined by the height of the nozzles 111 (the thickness of the silicon nozzle substrate 11) and the diameters of the nozzles 111 on the flow path surface S1 side and the ejection surface S2 side. The shape of the nozzles 111 such as the height and diameter is adjusted so that Equation 1 holds.

[0115] It should be noted that the number, formation position, and shape of the nozzles 111 in the silicon nozzle substrate 11 are not limited thereto. They are appropriately adjusted according to the design of the inkjet head 100 in such a way that at least Equation 1 holds. For example, the number and formation position of the nozzles 111 can also be formed by arranging four columns of a plurality of nozzles 111 in each row in a manner parallel to the long side direction as in the example shown later. Figure 16 shown, and regarding the shape of the nozzles 111, as Figure 9A and Figure 9B shown, the cross section can also be a shape that gradually decreases from the flow path surface S1 toward the ejection surface S2.

[0116] The silicon nozzle substrate 11 may be a plate-like body mainly composed of silicon (Si). For example, a substrate made of single-crystalline silicon with a (100) surface can be cited. In addition, as the silicon nozzle substrate 11, an SOI (Silicon On Insulator) substrate having an active layer of Si forming the nozzle 111 and a support layer, with an oxide film layer (also called a BOX layer) sandwiched between the active layer and the support layer, can also be used. By forming the nozzle substrate from a material mainly composed of silicon, the nozzle can be processed with high precision, and a nozzle substrate with less error in the position and deviation in the shape of the nozzle can be formed.

[0117] The thickness of the silicon nozzle substrate 11 is not particularly limited, but when it is in the range of 10 to 100 μm, the effects of the present invention are more significant and it is preferred. The thickness of the silicon nozzle substrate 11 is more preferably in the range of 30 to 60 μm.

[0118] The flow path substrate 12 has, as a flow path for ink: a through-flow path 125 that penetrates the substrate main body 12a so as to face the nozzle 111; and three individual circulation flow paths 121a, 121b, 121c, which communicate with the through-flow path 125 and extend in a direction away from the nozzle 111, and have a portion that overlaps the substrate main body 12a when viewed from above on the side opposite to the surface S3 of the flow path substrate 12 that is joined to the silicon nozzle substrate 11.

[0119] Specifically, the surface S3 of the flow path substrate 12 that is joined to the silicon nozzle substrate 11 is the lower surface S3 of the substrate main body 12a. The upper surface S4 of the substrate main body 12a is joined to the lower surface of the pressure chamber substrate 13 as shown in Figure 8A and Figure 8B .

[0120] From the viewpoints of facilitating the processing (high precision) of the through-flow path 125 and the individual circulation flow paths 121a, 121b, 121c, and being able to easily keep the ink temperature uniform due to the high thermal conductivity, the substrate main body 12a of the flow path substrate 12 is preferably made of silicon (Si), stainless steel (SUS), or 42 alloy. In addition, the pressure chamber substrate 13 can also use the same material. It should be noted that the materials constituting the substrate main body 12a of the flow path substrate 12 and the material constituting the pressure chamber substrate 13 are preferably materials with similar coefficients of thermal expansion.

[0121] The joining of the pressure chamber substrate 13 and the flow path substrate 12, and the joining of the flow path substrate 12 and the silicon nozzle substrate 11 can be performed, for example, by a known adhesive. The adhesive can be appropriately selected from known adhesives according to the constituent materials of each substrate.

[0122] Figure 8A This is a schematic cross-sectional view showing a case where the inkjet head chip 1 having a shear mode type pressure mechanism has a pressure chamber substrate 13 laminated on the laminate 10A, for example. The pressure chamber substrate 13 has an ink supply flow path 131 that communicates with the through-flow path 125 and has a diameter substantially the same as that of the through-flow path 125, and a common circulation flow path 134 that communicates with the individual circulation flow paths 121a. In the shear mode type pressure mechanism, for example, the through-flow path 125 and the supply flow path 131 function as pressure chambers. Specifically, in the pressure chamber substrate 13, for example, the partition walls that separate the respective supply flow paths 131 in the left-right direction are repeatedly displaced in the shear mode by the drive electrodes, thereby applying pressure to the ink in the pressure chamber and ejecting the ink from the nozzle 111.

[0123] At the same time, the ink in the pressure chamber is also discharged into the individual circulation flow paths 121a, 121b, and 121c. The common circulation flow path 134 is a flow path that extends in the left-right direction in a manner that communicates with the respective individual circulation flow paths 121a corresponding to the respective nozzles 111, and is a flow path that discharges the ink discharged from the respective individual circulation flow paths 121a to the outside of the inkjet head chip 1. It should be noted that the respective individual circulation flow paths 121b and 121c also communicate with other common circulation flow paths 134 provided in the pressure chamber substrate 13, and discharge the ink concentrated in the common circulation flow path 134 to the outside of the inkjet head chip 1.

[0124] Figure 8B This shows a cross-section of an example of an embodiment of an inkjet head chip having a bending mode type pressure mechanism. Figure 8B The shown inkjet head chip 1 has a silicon nozzle substrate 11 having an ink flow surface S1, an ejection surface S2, and a nozzle 111 that penetrates from the flow surface S1 to the ejection surface S2; a flow path substrate 12 joined to the flow surface S1 of the silicon nozzle substrate 11; a pressure chamber substrate 13 joined to the surface S4 on the side opposite to the surface S3 joined to the silicon nozzle substrate 11 of the flow path substrate 12; and a liquid-repellent film 14 provided on the ejection surface S2 of the silicon nozzle substrate 11.

[0125] In Figure 8B In the shown inkjet head chip 1, the flow path substrate 12 has, as an ink flow path, a through-flow path 125 that penetrates the substrate main body 12a so as to face the nozzle 111; an individual circulation flow path 121 that communicates with the through-flow path 125 and extends in a direction away from the nozzle 111, and has a portion that overlaps the substrate main body 12a when viewed from above on the side opposite to the surface S3 joined to the silicon nozzle substrate 11 of the flow path substrate 12; and a common circulation flow path 126 that communicates with the individual circulation flow path 121.

[0126] It should be noted that in Figure 8B the inkjet head chip 1 shown in Figure 8B , the flow path substrate 12 may also have a plurality of individual circulation flow paths 121 that communicate with the through-flow paths 125 located at positions facing the nozzles 111, similar to the laminate 10A. In this case, the cross-section obtained by cutting the inkjet head chip 1 with a plane orthogonal to the flow path surface S1 of the silicon nozzle substrate 11 in a manner that includes the center 111C of the nozzle 111 and the individual circulation flow paths 121 has the same shape in each individual circulation flow path 121.

[0127] The common circulation flow path 126 has the same function as the common circulation flow path 134 provided in the pressure chamber substrate 13 in the Figure 8A inkjet head chip 1 shown in Figure 8A . In the Figure 8B inkjet head chip 1 shown in Figure 8B , this common circulation flow path is provided as the common circulation flow path 126 within the flow path substrate 12. The common circulation flow path 126 is a flow path that extends and is arranged in the left-right direction in a manner that communicates with each corresponding individual circulation flow path 121, and is a flow path that discharges the ink discharged from each individual circulation flow path 121 to the outside of the inkjet head chip 1.

[0128] Therefore, in the flow path substrate 12 of the inkjet head chip 1 in Figure 8B Figure 8B , the individual circulation flow path 121 has a connection portion 122 and an extension portion 123 with respect to the individual circulation flow path 121 of the inkjet head chip 1 shown in Figure 8A as described later, and is composed only of the connection portion 122. Figure 8A

[0129] Figure 8B The pressure chamber substrate 13 of the inkjet head chip 1 shown in sequentially has a pressure chamber layer 13a, a diaphragm 13V, and a spacer layer 13b having a space 13S in contact with the diaphragm 13V and having a piezoelectric element 13P on the diaphragm 13V inside the space 13S, starting from the side of the flow path substrate 12.

[0130] The pressure chamber substrate 13 has an ink supply flow path 131 that penetrates the spacer layer 13b, the diaphragm 13V, and the pressure chamber layer 13a and communicates with the through-flow path 125 of the flow path substrate 12. The supply flow path 131 exists as a supply flow path 131a with a large diameter and serving as a main pressure chamber in the pressure chamber layer 13a. The supply flow path 131 exists as a supply flow path 131b with a diameter smaller than that of the supply flow path 131a in the spacer layer 13b and the diaphragm 13V. The inlet of the supply flow path 131b becomes the inlet of the ink supplied from the manifold 5 to the inkjet head chip 1, and supplies the ink to the pressure chamber constituted by the supply flow path 131a and the through-flow path 125.

[0131] Figure 8B In Figure 8BIn the inkjet head chip 1 shown, in the pressure chamber substrate 13 by a bending-mode pressure mechanism, the piezoelectric element 13P is displaced through the drive electrode, whereby the diaphragm 13V is displaced, thereby applying pressure to the ink in the pressure chamber (supply flow path 131a and through-flow path 125), and the ink is ejected from the nozzle 111.

[0132] It should be noted that the following describes the case where in the laminate 10A of the liquid-repellent film 14, the silicon nozzle substrate 11, and the flow path substrate 12 included in the inkjet head chip 1 shown, the positional relationship between the individual circulation flow path 121 and the nozzle 111 satisfies Equation 1. However, in Figure 8A the laminate of the liquid-repellent film 14, the silicon nozzle substrate 11, and the flow path substrate 12 included in the inkjet head chip 1 shown, the positional relationship between the individual circulation flow path 121 and the nozzle 111 also satisfies Equation 1. Similarly to that described later, in Figure 8B Y represents the position of the height of L×tanφ on the formation surface F1 of the through-flow path 125. In Figure 8B In the cross-sectional view of Figure 8B it can also be seen that the positional relationship between the individual circulation flow path 121 and the nozzle 111 satisfies Equation 1, that is, the position Y of the height of L×tanφ is located above the inlet of the individual circulation flow path 121.

[0133] In the case where the pressure chamber substrate 13 is either a shear-mode or a bending-mode pressure mechanism, the ink present in the through-flow path 125 is ejected from the nozzle 111 by being pressurized. In the flow path substrate 12 of the laminate 10A, as long as the through-flow path 125 is formed by penetrating the substrate main body 12a and is located at a position facing the nozzle 111, the size and position in plan view are not particularly limited. Usually, the through-flow path 125 has a diameter larger than the diameter of the nozzle 111 in plan view. The flow path of the ink is formed by the inner wall surface of the substrate main body 12a of the flow path substrate 12. This inner wall surface is referred to as the formation surface of the ink flow path. F1 represents the formation surface of the through-flow path 125 in the substrate main body 12a.

[0134] The number of through-flow paths 125 corresponding to one nozzle 111 is usually one. In Figure 6 and Figure 7 the flow path substrate 12 shown, the through-flow path 125 communicates with three individual circulation flow paths 121a, 121b, and 121c. The number n of individual circulation flow paths corresponding to one through-flow path 125 is not particularly limited as long as it is 1 or more. It is preferably 1 to 4, and more preferably one or two from the viewpoint of ease of manufacturing.

[0135] The individual circulation channels 121a, 121b, and 121c each have portions (hereinafter also referred to as "connection portions") 122a, 122b, and 122c that communicate with the through-channel 125 and extend in a direction away from the nozzle 111. The connection portions 122a, 122b, and 122c are portions that overlap the substrate main body 12a when viewed from above, that is, when viewed from the upper surface S4 side of the substrate main body 12a, on the opposite side of the surface S3 of the flow path substrate 12 that is joined to the silicon nozzle substrate 11.

[0136] In Figure 6 and Figure 7 In the flow path substrate 12 shown, the individual circulation channels 121a, 121b, and 121c each further have extension portions 123a, 123b, and 123c that extend upward from the end of the connection portions 122a, 122b, and 122c that is farthest from the nozzle 111 and reach the position of the upper surface S4 of the substrate main body 12a. In Figure 7 In the substrate main body 12a shown, the formation surfaces of the connection portions 122a, 122b, and 122c of the individual circulation channels 121a, 121b, and 121c are denoted by F2. In addition, the formation surfaces of the extension portions 123a, 123b, and 123c are denoted by F3. Hereinafter, when referring to the individual circulation channels regardless of the number, the individual circulation channel 121 is used. Similarly, when referring to the connection portions and the extension portions regardless of the number, the connection portion 122 and the extension portion 123 are used.

[0137] In Figure 6 and Figure 7 In the flow path substrate 12 shown, the connection portions 122a, 122b, and 122c of the individual circulation channels 121a, 121b, and 121c are arranged such that the flow path cross-section is rectangular and is parallel to the flow path surface S1 of the silicon nozzle substrate 11 with the flow path surface S1 as the lower surface. The upper surface of the connection portions 122a, 122b, and 122c is the formation surface F2 of the substrate main body 12a that is arranged to face the flow path surface S1.

[0138] The shape and formation position of the flow path cross-section of the connection portions 122a, 122b, and 122c are not limited to this as long as the conditions of the following formula 1 are satisfied. For example, the flow path cross-section of the connection portions 122a, 122b, and 122c may also be a circle including an ellipse, a polygon, etc. In addition, as Figure 9A shown, the upper surface and the lower surface of the connection portions 122a, 122b, and 122c may also be constituted by a pair of formation surfaces F2 formed on the substrate main body 12a in a manner parallel to the flow path surface S1 of the silicon nozzle substrate 11 and facing each other with a predetermined distance therebetween. In addition, in this case, as Figure 9BAs shown, the upper and lower surfaces of the connecting portions 122a, 122b, and 122c may also be provided at a predetermined angle with respect to the flow path surface S1 of the silicon nozzle substrate 11.

[0139] In the laminate 10A, the liquid-repellent film 14 is formed so as to cover the entire ejection surface S2 of the silicon nozzle substrate 11. The liquid-repellent film 14 is not formed on the surface of components other than the ejection surface S2. Specifically, it is not formed on the flow path surface S1 of the silicon nozzle substrate 11, the formation surface of the nozzle 111, and the inner wall surface of the flow path substrate 12. The inner wall surface of the flow path substrate 12 is, for example, the formation surface F1 of the through-flow path 125, the formation surfaces F2 of the connecting portions 122a, 122b, and 122c of the individual circulation flow paths 121a, 121b, and 121c, and the formation surfaces F3 of the extension portions 123a, 123b, and 123c.

[0140] In the laminate 10A of the present invention, the positional relationship between each of the individual circulation flow paths 121a, 121b, and 121c and the nozzle 111 satisfies the following formula 1.

[0141] L×tanφ>H1 Formula 1

[0142] In the cross-section obtained by cutting the silicon nozzle substrate 11 and the flow path substrate 12 with a plane orthogonal to the flow path surface S1 of the silicon nozzle substrate 11 so as to include the center 111C of the nozzle 111 and the individual circulation flow paths 121a, 121b, or 121c, each symbol in Formula 1 represents the following meaning. Figure 7 The cross-sectional view of the laminate 10A shown is a cross-section obtained by cutting the laminate 10A with a plane orthogonal to the flow path surface S1 of the silicon nozzle substrate 11 so as to include the center 111C of the nozzle 111 and the individual circulation flow path 121a. Hereinafter, Figure 7 the following cross-sectional view is used to explain Formula 1.

[0143] φ is the angle formed by the straight line connecting the first nozzle end ( Figure 7 in, the nozzle end represented by “A”, hereinafter also referred to as “nozzle end A”) located on the side of the ejection surface S2 away from the individual circulation flow path 121a and the second nozzle end ( Figure 7 in, the nozzle end represented by “B”, hereinafter also referred to as “nozzle end B”) located on the side of the flow path surface S1 close to the individual circulation flow path 121a and the ejection surface S2.

[0144] L is the distance from the straight line SL orthogonal to the ejection surface S2 including the nozzle end A to the intersection point X, which is the farthest from the flow path surface S1, among the intersection points of the formation surface F1 of the through-flow path 125 in the substrate main body 12a and the formation surface of the individual circulation flow path 121a. As described above, the individual circulation flow path 121a is composed of a connection part 122a communicating with the through-flow path 125 and an extension part 123a extending from the connection part 122a. Therefore, the intersection point of the formation surface F1 of the through-flow path 125 in the substrate main body 12a and the formation surface of the individual circulation flow path 121a refers to the intersection point of the formation surface F1 of the through-flow path 125 in the substrate main body 12a and the formation surface F2 of the connection part 122a.

[0145] In the flow path substrate 12 of the laminate 10A, the connection part 122a of the individual circulation flow path 121a uses the flow path surface S1 of the silicon nozzle substrate 11 as the lower surface. Therefore, in Figure 7 the cross-section shown, the intersection point of the formation surface F1 and the formation surface F2 is one point, and this point becomes the intersection point X that is the farthest from the flow path surface S1. The intersection point X represents the point that is the farthest from the flow path surface S1 at the boundary between the through-flow path 125 and the connection part 122a. In other words, the intersection point X represents the point that is the farthest from the flow path surface S1 at the entrance of the connection part 122a. For example, as Figure 9A and Figure 9B shown, there are two intersection points of the formation surface F1 and the formation surface F2, and in the present invention, the point that is the farthest from the flow path surface S1 among them is used as the intersection point X for the index.

[0146] H1 is the distance from the ejection surface S2 to the intersection point X, which is the farthest from the flow path surface S1, among the intersection points of the formation surface F1 of the through-flow path 125 in the substrate main body 12a and the formation surface of the individual circulation flow path 121a.

[0147] In Figure 7 , the lengths of L×tanφ and H1 are arranged and represented by a double-headed dotted arrow. Hereinafter, the position that is L×tanφ away from the ejection surface S2 upward is called the height of L×tanφ, and in Figure 7 , Y represents the position of the height of L×tanφ on the formation surface F1 of the through-flow path 125.

[0148] As Figure 7 shown, it can be seen that in the laminate 10A, the positional relationship between the individual circulation flow path 121a, specifically the entrance of the connection part 122a of the individual circulation flow path 121a and the nozzle 111 satisfies Equation 1. In other words, in Figure 7In this case, the position Y at the height of L×tanφ on the formation surface F1 of the through-flow path 125 is located above the intersection point X, which is the farthest from the flow path surface S1 among the intersection points of the formation surface F1 of the through-flow path 125 and the formation surface of the individual circulation flow path 121a in the substrate main body 12a. By making the positional relationship between the inlet of the connection portion 122a of the individual circulation flow path 121a and the nozzle 111 satisfy Equation 1, when forming the liquid-repellent film 14 on the ejection surface S2, the liquid-repellent film will not be formed at a difficult-to-remove portion on the inner wall surface of the flow path substrate 12, and the liquid-repellent film formed on the inner wall surface of the flow path substrate 12 can be efficiently removed through subsequent processing.

[0149] As the liquid-repellent film 14, for example, a liquid-repellent film composed of a fluoropolymer layer can be cited. The liquid-repellent film 14 preferably further includes a silicon compound base layer and a fluoropolymer layer sequentially provided from the ejection surface S2 side of the silicon nozzle substrate 11.

[0150] Here, the formation of the liquid-repellent film 14 can be carried out, for example, on the ejection surface S2 of the silicon nozzle substrate 11 alone before joining the silicon nozzle substrate 11 and the flow path substrate 12, or on the ejection surface S2 of the silicon nozzle substrate 11 in the laminate after joining the silicon nozzle substrate 11 and the flow path substrate 12. However, it is difficult to perform the treatment on the silicon nozzle substrate 11 alone, especially difficult to treat the silicon nozzle substrate 11 with the above-mentioned preferred thickness as a single body. Therefore, the formation of the liquid-repellent film 14 is usually carried out on the laminate after joining the silicon nozzle substrate 11 and the flow path substrate 12.

[0151] As the fluoropolymer layer, a layer formed from a raw material fluoropolymer having a hydrolyzable silyl group and a long-chain hydrocarbon group substituted with a fluorine atom or a polyoxyalkylene group substituted with a fluorine atom is preferably used. As the raw material fluoropolymer, a perfluoropolyether compound having a hydrolyzable silyl group is preferred. This perfluoropolyether compound more preferably has a fluoroalkyl group at the end different from the end having a hydrolyzable silyl group, and preferably has a perfluoroalkyl group. As the raw material fluoropolymer, commercially available products such as OPTOOL (registered trademark, manufactured by Daikin Industries, Ltd.) can also be used.

[0152] If the raw material fluoropolymer has a hydrolyzable silyl group, for example, a silanol group (Si-OH group) is formed on the ejection surface S2 of the silicon nozzle substrate 11, and a hydrolysis condensation reaction is carried out between this silanol group and the above-mentioned hydrolyzable silyl group, thereby enabling a strong siloxane bond (Si-O-Si) to be formed between the silicon nozzle substrate 11 and the liquid-repellent film 14. As a result, the durability of the liquid-repellent film 14 is improved. The liquid-repellent film 14 formed in this way exists on the surface by extending the fluoropolymer chain, for example, the perfluoropolyether chain, from the binding end with the silicon nozzle substrate 11, and further has liquid-repellent properties, for example, by having a structure with a perfluoroalkyl group on the outermost surface.

[0153] Furthermore, a base layer containing a silicon compound may also be formed on the ejection surface S2 of the silicon nozzle substrate 11, and a fluoropolymer layer may be formed on this base layer, thereby forming a siloxane bond (Si-O-Si) between the base layer and the fluoropolymer layer. The base layer preferably has a silicon oxide (SiO2) layer at least on the fluoropolymer layer side. The base layer can be formed by known methods such as evaporation, sputtering, and CVD. The thickness of the base layer can be approximately 10 to 100 nm.

[0154] When forming a liquid-repellent film 14, such as a fluoropolymer layer, on the ejection surface S2 of the silicon nozzle substrate 11, for example, a method of applying a composition containing a raw material fluoropolymer (hereinafter referred to as "liquid repellent") to the ejection surface S2 and curing it is used. Curing includes drying and reaction, such as the above hydrolysis condensation reaction. The liquid repellent can be composed only of the raw material fluoropolymer or can contain a solvent. Furthermore, any solid component can also be contained as needed. As a method of applying the liquid repellent, evaporation and the like can be cited.

[0155] For example, in the case of a laminate formed by bonding the flow path substrate 12 and the silicon nozzle substrate 11, when forming a liquid-repellent film 14, specifically a fluoropolymer layer, by evaporation from the ejection surface S2 side of the silicon nozzle substrate 11, the liquid repellent as the evaporation source is arranged on the ejection surface S2 side for evaporation. By evaporation, the liquid repellent adheres to the ejection surface S2 of the silicon nozzle substrate 11 and the inner wall surface (forming surface) of the nozzle 111, and enters the inside of the flow path substrate 12 from the nozzle 111 and adheres to the inner wall surface of the substrate main body 12a. At this time, in the substrate main body 12a of the flow path substrate 12, the liquid repellent does not adhere to the inner wall surface up to the position Y at a height of L×tanφ from the ejection surface S2, but adheres to the inner wall surface above it.

[0156] When observing in the Figure 7 shown cross-sectional view, the positional relationship between the inlet of the connection portion 122a of the individual circulation flow path 121a and the nozzle 111 satisfies Equation 1. That is, the whole of the inlet of the connection portion 122a of the individual circulation flow path 121a is located at a position lower than the position Y at a height of L×tanφ. As a result, the liquid repellent does not adhere to the forming surface F2 of the connection portion 122a of the individual circulation flow path 121a and the portion of the flow path surface S1 corresponding to the lower surface of the connection portion 122a in the substrate main body 12a.

[0157] After vapor-depositing the liquid repellent agent, the liquid repellent agent adhering to the above-described position of the laminate of the flow path substrate 12 and the silicon nozzle substrate 11 is cured to form a liquid repellent film. Since curing is usually performed by heating, when heating, the liquid repellent agent that enters the inside of the flow path substrate 12 and adheres to the inner wall surface, specifically, the inner wall surface at a position above the position Y at a height of L×tanφ, also cures in the same manner to become a liquid repellent film. After curing, the liquid repellent film formed on the inner wall surface of the flow path substrate 12 can be selectively removed by performing treatment, such as UV ozone irradiation or oxygen plasma irradiation, from the side of the flow path substrate 12 opposite to the silicon nozzle substrate 11, that is, the upper side.

[0158] In UV ozone irradiation and oxygen plasma irradiation, the irradiation cannot reach the portion that overlaps with the substrate main body 12a when viewed from the upper side of the flow path substrate 12. Therefore, assuming that a liquid repellent film is formed on the formation surface F2 of the connection portion 122a of the individual circulation flow path 121a and the flow path surface S1 corresponding to the lower surface of the connection portion 122a, it is almost impossible to remove the liquid repellent film by this method. In Figure 7 In the cross-section shown above, as described above, a liquid repellent film is not formed on the formation surface F2 of the connection portion 122a of the individual circulation flow path 121a and the flow path surface S1 corresponding to the lower surface of the connection portion 122a. Therefore, by performing UV ozone irradiation or oxygen plasma irradiation from the upper side of the flow path substrate 12, almost all of the liquid repellent film formed on the inner wall surface of the flow path substrate 12 can be removed. In addition, the liquid repellent film formed on the formation surface of the nozzle 111 can also be removed by this method.

[0159] In this way, as in Figure 7 the cross-section shown, a laminate 10A in which a liquid repellent film 14 is formed only on the ejection surface S2 of the silicon nozzle substrate 11 can be obtained. It should be noted that the liquid repellent film 14 does not necessarily have to be formed on the entire surface of the ejection surface S2 as long as it is formed at least around the nozzle 111, but it is preferably formed on the entire surface.

[0160] The above has described Figure 7 the case where the cross-section obtained by cutting the laminate 10A with a plane orthogonal to the flow path surface S1 of the silicon nozzle substrate 11 in a manner including the center 111C of the nozzle 111 and the individual circulation flow path 121a as shown satisfies Equation 1. In the laminate 10A, in the cross-section obtained by cutting with a plane orthogonal to the flow path surface S1 of the silicon nozzle substrate 11 in a manner including the center 111C of the nozzle 111 and the individual circulation flow path 121b, that is, the cross-section obtained by cutting the laminate 10A along B-B Figure 6 shown, Equation 1 is also satisfied. And in the cross-section obtained by cutting with a plane orthogonal to the flow path surface S1 of the silicon nozzle substrate 11 in a manner including the center 111C of the nozzle 111 and the individual circulation flow path 121c, that is, the cross-section obtained by cutting along C-CFigure 6 In the cross section obtained from the laminate 10A shown, Equation 1 is also satisfied.

[0161] Thus, by satisfying Equation 1 with respect to the positional relationship between the three individual circulation channels 121a, 121b, and 121c in the laminate 10A and the nozzle 111, in the laminate 10A, when forming the liquid-repellent film 14 on the ejection surface S2, the liquid-repellent film is not formed at a difficult-to-remove portion on the inner wall surface of the flow path substrate 12, and the liquid-repellent film formed on the inner wall surface of the flow path substrate 12 can be efficiently removed by subsequent processing.

[0162] Next, the application of Equation 1 in the case where the cross section of the nozzle 111 in the silicon nozzle substrate 11 gradually decreases from the flow path surface S1 toward the ejection surface S2 will be described using Figure 9A and Figure 9B .

[0163] Figure 9A The laminate 10B showing the cross section in Figure 9B and the laminate 10C showing the cross section in

[0164] are laminates that are substantially the same as the laminate 10A in the enlarged plan view of the periphery of the nozzle 111 observed from the flow path substrate 12 side. Specifically, the laminate 10A, the laminate 10B, and the laminate 10C are laminates that are the same in plan view except for the different diameters on the flow path surface S1 of the nozzle 111. The laminate 10B and the laminate 10C have a structure in which the diameter of the nozzle 111 in plan view gradually decreases from the flow path surface S1 toward the ejection surface S2.

[0165] Figure 9A The cross-sectional view of the laminate 10B shown is a cross section obtained by cutting with a plane orthogonal to the flow path surface S1 of the silicon nozzle substrate 11 so as to include the center 111C of the nozzle 111 and the individual circulation channel 121a. Figure 9A The difference between the laminate 10B shown and the laminate 10A is that, with respect to the silicon nozzle substrate 11, the cross section of the nozzle 111 decreases in two stages from the flow path surface S1 toward the ejection surface S2. The diameter of the opening portion of the nozzle 111 on the flow path surface S1 in the laminate 10B is larger than that of the nozzle 111 in the laminate 10A, and the diameter is significantly reduced in the first stage from the flow path surface S1 toward the ejection surface S2, and there is no diameter reduction in the second stage.

[0166] In the case of a structure in which the diameter of the nozzle 111 of the silicon nozzle substrate 11 in a plan view decreases stepwise from the flow path surface S1 toward the ejection surface S2, as φ in Equation 1, the maximum angle among the angles formed by the straight line connecting the nozzle end A (the nozzle end on the side of the ejection surface S2 away from the individual circulation flow path 121a) and the end on the side of the flow path surface S1 of each stage and closer to the individual circulation flow path 121a with the ejection surface S2 is used.

[0167] In the laminate 10B, in the first stage from the flow path surface S1 toward the ejection surface S2, the end on the side of the flow path surface S1 and closer to the individual circulation flow path 121a is Figure 9A denoted by B2 in Figure 9A . Further, in the second stage from the flow path surface S1 toward the ejection surface S2, the end on the side of the flow path surface S1 and closer to the individual circulation flow path 121a is

[0168] denoted by B1 in Figure 9A . When comparing the angle formed by the straight line connecting the nozzle end A and the nozzle end B2 with the ejection surface S2 and the angle formed by the straight line connecting the nozzle end A and the nozzle end B1 with the ejection surface S2, the angle formed by the straight line connecting the nozzle end A and the nozzle end B1 with the ejection surface S2 is larger. Therefore, this angle is set as φ in Equation 1.

[0169] Further, Figure 9A the lengths of L×tanφ and H1 are arranged and indicated by a dotted double arrow in Figure 9A . In Figure 9A , the position of the height of L×tanφ on the formation surface F1 of the through-flow path 125 is denoted by Y. As Figure 9A shown, it can be seen that in the laminate 10B as well as in the laminate 10A, the positional relationship between the individual circulation flow path 121a, specifically the inlet of the connecting portion 122a of the individual circulation flow path 121a and the nozzle 111 satisfies Equation 1. That is, in Figure 9A , the position Y of the height of L×tanφ on the formation surface F1 of the through-flow path 125 is located above the intersection point X, which is the farthest from the flow path surface S1 among the intersection points of the formation surface F1 of the through-flow path 125 and the formation surface of the individual circulation flow path 121a in the substrate main body 12a.

[0170] Further, in the laminate 10B, Equation 1 is also satisfied in a cross-section obtained by cutting the laminate 10B with a plane orthogonal to the flow surface S1 of the silicon nozzle substrate 11 so as to include the center 111C of the nozzle 111 and the individual circulation flow path 121b, and in a cross-section obtained by cutting the laminate 10B with a plane orthogonal to the flow surface S1 of the silicon nozzle substrate 11 so as to include the center 111C of the nozzle 111 and the individual circulation flow path 121c.

[0171] In this way, by satisfying Equation 1 with respect to the positional relationship between the nozzle 111 and each of the three individual circulation flow paths 121a, 121b, and 121c in the laminate 10B, when forming the liquid-repellent film 14 on the ejection surface S2 in the laminate 10B, the liquid-repellent film is not formed at a difficult-to-remove portion on the inner wall surface of the flow path substrate 12, and the liquid-repellent film formed on the inner wall surface of the flow path substrate 12 can be efficiently removed by subsequent processing.

[0172] Figure 9B The cross-sectional view of the laminate 10C shown is a cross-section obtained by cutting the laminate 10C with a plane orthogonal to the flow surface S1 of the silicon nozzle substrate 11 so as to include the center 111C of the nozzle 111 and the individual circulation flow path 121a. Figure 9B The difference between the laminate 10C shown and the laminate 10A is that, with respect to the silicon nozzle substrate 11, the cross-section of the nozzle 111 decreases in two stages from the flow surface S1 toward the ejection surface S2. The diameter of the opening portion of the nozzle 111 on the flow surface S1 in the laminate 10C is larger than that of the nozzle 111 in the laminate 10A, and the diameter is decreased in the first stage from the flow surface S1 toward the ejection surface S2, and there is no decrease in diameter in the second stage. Compared with the laminate 10B, in the laminate 10C, the diameter of the opening portion of the flow surface S1 is smaller than that of the nozzle 111 in the laminate 10B, and the reduction ratio of the diameter in the first stage is small.

[0173] In the laminate 10C, in the first stage from the flow surface S1 toward the ejection surface S2, the end portion on the side of the flow surface S1 and close to the individual circulation flow path 121a is Figure 9B denoted by B2 in Figure 9B . Further, in the second stage from the flow surface S1 toward the ejection surface S2, the end portion on the side of the flow surface S1 and close to the individual circulation flow path 121a is

[0174] denoted by B1 in Figure 9BThe difference between the laminate 10C shown and the laminate 10A is that, regarding the flow path substrate 12, both the upper surface and the lower surface of the connection part 122a of the individual circulation flow path 121a are formed by the formation surface F2 in the substrate main body 12a, and are inclined so as not to be parallel to the flow path surface S1 and to rise toward the extension part 123a. Therefore, in the laminate 10C, there are two intersection points between the formation surface F1 of the through-flow path 125 and the formation surface F2 of the connection part 122a. The intersection point X related to L used in Equation 1 is the intersection point farthest from the flow path surface S1 among these intersection points, that is, the point farthest from the flow path surface S1 at the entrance of the connection part 122a.

[0175] In Figure 9B , the lengths of L×tanφ and H1 are arranged and represented by a dotted double arrow. In Figure 9B , the position of the height of L×tanφ on the formation surface F1 of the through-flow path 125 is represented by Y. As Figure 9B shown, it can be seen that in the laminate 10C, similar to the laminate 10A, the positional relationship between the individual circulation flow path 121a, specifically the entrance of the connection part 122a of the individual circulation flow path 121a and the nozzle 111 satisfies Equation 1. That is, in Figure 9B , the position Y of the height of L×tanφ on the formation surface F1 of the through-flow path 125 is located above the intersection point X farthest from the flow path surface S1 among the intersection points between the formation surface F1 of the through-flow path 125 in the substrate main body 12a and the formation surface of the individual circulation flow path 121a.

[0176] Moreover, in the laminate 10C, Equation 1 is also satisfied in the cross-section obtained by cutting with a plane orthogonal to the flow path surface S1 of the silicon nozzle substrate 11 including the center 111C of the nozzle 111 and the individual circulation flow path 121b, and in the cross-section obtained by cutting with a plane orthogonal to the flow path surface S1 of the silicon nozzle substrate 11 including the center 111C of the nozzle 111 and the individual circulation flow path 121c.

[0177] In this way, by satisfying Equation 1 in the positional relationship between all three individual circulation flow paths 121a, 121b, and 121c of the laminate 10C and the nozzle 111, in the laminate 10C, when forming the liquid-repellent film 14 on the ejection surface S2, the liquid-repellent film will not be formed at the difficult-to-remove parts on the inner wall surface of the flow path substrate 12, and the liquid-repellent film formed on the inner wall surface of the flow path substrate 12 can be efficiently removed through subsequent processing.

[0178] Next, use Figure 10 and Figure 11, the application of Formula 2 will be described for a laminate in which, when viewed from above the upper surface S4 side of the flow path substrate 12, the center of the nozzle 111 coincides with the center of the through-flow path 125, and in a cross-section obtained by cutting with a plane orthogonal to the flow path surface S1 of the silicon nozzle substrate 11 in a manner including the center of the nozzle 111, the center of the through-flow path 125, and the two individual circulation flow paths 121, the two individual circulation flow paths 121 are in a symmetric relationship.

[0179] Figure 10 is viewed from the flow path substrate 12 side Figure 2 An enlarged plan view of the periphery of the nozzle 111 of the laminate 10D, which is an example of a laminate of the flow path substrate 12, the silicon nozzle substrate 11, and the liquid-repellent film 14 in the inkjet head 100 shown in Figure 11 is a cross-sectional view obtained by cutting along XI-XI of Figure 10 the laminate 10D shown in

[0180] As Figure 10 shown, the laminate 10D has two individual circulation flow paths 121a and 121b. These individual circulation flow paths 121a and 121b are located on a straight line passing through the center of the nozzle 111 on the flow path surface S1. When viewed from above the upper surface S4 side of the flow path substrate 12, the center 111C of the nozzle 111 coincides with the center 125C of the through-flow path 125. The silicon nozzle substrate 11 and the liquid-repellent film 14 in the laminate 10D have the same structure as the laminate 10A.

[0181] The flow path substrate 12 of the laminate 10D has two individual circulation flow paths 121a and 121b, each having connecting portions 122a and 122b extending forward and backward with the through-flow path 125 as the center. A cross-section obtained by cutting the laminate 10D along XI-XI Figure 11 shown is a cross-section obtained by cutting with a plane orthogonal to the flow path surface S1 of the silicon nozzle substrate 11 in a manner including the center of the nozzle 111, the center of the through-flow path 125, and the two individual circulation flow paths 121a, 121b. In the Figure 11 cross-section shown, with the through-flow path 125 as the center, the two individual circulation flow paths 121a, 121b are in a symmetric relationship.

[0182] The individual circulation flow path 121a in the flow path substrate 12 of the laminate 10D has the same structure as the individual circulation flow path 121a in the flow path substrate 12 of the laminate 10A, and is composed of a connecting portion 122a that communicates with the through-flow path 125 and extends in a direction away from the nozzle 111, and an extension portion 123a that extends upward from the end portion of the connecting portion 122a on the side farthest from the nozzle 111 and reaches the upper surface S4 of the substrate main body 12a. Similarly, the individual circulation flow path 121b that is in a symmetric relationship with the individual circulation flow path 121a is also composed of a connecting portion 122b that communicates with the through-flow path 125 and extends in a direction away from the nozzle 111, and an extension portion 123b that extends upward from the connecting portion 122b and reaches the upper surface S4 of the substrate main body 12a.

[0183] In the laminate 10D of the present invention, in Figure 11 the cross section shown, the positional relationship between each of the individual circulation flow paths 121a and 121b and the nozzle 111 satisfies Equation 1. When explaining Equation 1 for the positional relationship between the individual circulation flow path 121a and the nozzle 111, the nozzle end portion located on the side of the ejection surface S2 away from the individual circulation flow path 121a is designated as Ai, and the nozzle end portion located on the side of the flow path surface S1 close to the individual circulation flow path 121a is designated as Bi. The angle of the straight line connecting the nozzle end portion Ai and the nozzle end portion Bi with the ejection surface S2 is φ, and L×tanφ is obtained in the same manner as in the case of the laminate 10A.

[0184] On the other hand, when explaining Equation 1 for the positional relationship between the individual circulation flow path 121b and the nozzle 111, the nozzle end portion located on the side of the ejection surface S2 away from the individual circulation flow path 121b is designated as Aii, and the nozzle end portion located on the side of the flow path surface S1 close to the individual circulation flow path 121a is designated as Bii. The angle of the straight line connecting the nozzle end portion Aii and the nozzle end portion Bii with the ejection surface S2 is φ, and L×tanφ is obtained in the same manner as in the case of the laminate 10A. The individual circulation flow path 121a and the individual circulation flow path 121b have the above-described symmetric positional relationship, and the angle φ and L×tanφ represent the same value.

[0185] In Figure 11 , Y represents the position of the height of L×tanφ on the formation surface F1 of the through-flow path 125. It should be noted that in Figure 11 , the description of L is omitted. In addition, H3 represents the distance from the flow path surface S1 of the silicon nozzle substrate 11 to the position Y of the height of L×tanφ.

[0186] As Figure 11As shown, it can be seen that in laminate 10D, similar to laminate 10A, the positional relationships between the individual circulation channels 121a and 121b, specifically the inlets of the connecting portions 122a and 122b of the individual circulation channels 121a and 121b, and the nozzle 111 respectively satisfy Equation 1. That is, in Figure 11 the position Y at the height of L×tanφ on the formation surface F1 of the individual circulation channel 121a side of the through-channel 125 is located above the intersection point X between the formation surface F1 of the through-channel 125 and the formation surface F2 of the individual circulation channel 121a in the substrate body 12a. Similarly, the position Y at the height of L×tanφ on the formation surface F1 of the individual circulation channel 121b side of the through-channel 125 is located above the intersection point X between the formation surface F1 of the through-channel 125 and the formation surface F2 of the individual circulation channel 121b in the substrate body 12a.

[0187] In addition, in laminate 10D, the positional relationships between the individual circulation channels 121a and 121b, the through-channel 125, and the nozzle 111 satisfy the following Equation 2.

[0188] (W - D2) / (D1 + D2)×t > H2 Equation 2

[0189] Each symbol in Equation 2 represents the following meanings in a cross-section obtained by cutting with a plane orthogonal to the flow surface S1 of the silicon nozzle substrate 11 in a manner that includes the center of the nozzle 111 and the through-channel 125 and the two individual circulation channels 121a and 121b, that is, the cross-section shown in Figure 11 Shown. Hereinafter, Equation 2 will be described using the cross-sectional view shown in Figure 11 Shown.

[0190] D1 is the diameter of the nozzle 111 on the ejection surface S2 of the silicon nozzle substrate 11. D2 is the diameter of the nozzle 111 on the flow surface S1 of the silicon nozzle substrate 11. t is the thickness of the silicon nozzle substrate 11. Regarding D1, D2, and t in the silicon nozzle substrate 11, it is preferably in the same range as that described for laminate 10A.

[0191] W is the width of the through-channel 125, and in Figure 11 it is the distance between the formation surface F1 of the through-channel 125 on the side connected to the individual circulation channel 121a and the formation surface F1 of the through-channel 125 on the side connected to the individual circulation channel 121b.

[0192] H2 is the distance from the flow surface S1 of the silicon nozzle substrate 11 to the intersection point X that is the farthest from the flow surface S1 among the intersection points between the formation surface F1 of the through-channel 125 in the substrate body 12a and the formation surfaces F2 of the individual circulation channels 121a and 121b.

[0193] (W - D2) / (D1 + D2)×t in Equation 2 is equivalent to the distance H3 from the flow path surface S1 of the silicon nozzle substrate 11 to the position Y at a height of L×tanφ as shown in the following Equation 3. Further, H3 can also be obtained using φ by the following Equation 4.

[0194] (W - D2) / (D1 + D2)×t = H3 Equation 3

[0195] H3 = (W - D2) / (2×tanφ) Equation 4

[0196] In Figure 11 , H3 and H2 are arranged near the entrance of the individual circulation flow path 121b and are indicated by a double-headed dotted arrow. As Figure 11 shows, in the laminate 10D, regarding the positional relationship of the individual circulation flow paths 121a and 121b, the through-flow path 125, and the nozzle 111, H3 > H2, and it can be seen that Equation 2 is satisfied. Thus, in the laminate 10D, satisfying Equation 1 and satisfying Equation 2 have the same meaning. By making the positional relationship of the individual circulation flow paths 121a and 121b, the through-flow path 125, and the nozzle 111 satisfy Equation 1 and Equation 2, when forming the liquid-repellent film 14 on the ejection surface S2, the liquid-repellent film is not formed at the difficult-to-remove part on the inner wall surface of the flow path substrate 12, and the liquid-repellent film formed on the inner wall surface of the flow path substrate 12 can be efficiently removed by subsequent processing.

[0197] Next, as a modification example of the inkjet head chip 1 included in the inkjet head 100 of the present embodiment, an example in which the number of columns of the nozzles 111 is 4 columns will be described with reference to Figures 12 to 18B As described above, the number of columns and the arrangement of the nozzles 111 can be appropriately changed. For example, as described above, it can be 1 column, or any one of 2 to 3 columns, or 5 columns or more.

[0198] Figure 12 is Figure 1 a bottom view of an example different from the head unit shown in Figure 2 of the head unit 224 of the inkjet recording apparatus 200 shown in Figure 2 In the inkjet head 100 shown in Figure 12 , the number of columns of the nozzles 111 is 1 column. In contrast, in the head unit 224 shown in Figure 3 and Figure 4 , the number of columns of the nozzles 111 in the inkjet head 100 is 4 columns. The three-dimensional view of the inkjet head 100 with 4 columns of nozzles 111 and the cross-sectional view in the left-right direction at the bottom of the inkjet head 100 are the same as those shown in

[0199] Figure 13 represents Figure 12 an exploded three-dimensional view of the inkjet head chip 1 of the inkjet head 100 constituting the head unit 224 shown inFigure 14A and Figure 14B respectively represent Figure 13 the top view and the bottom view of the pressure chamber substrate 13 of the inkjet head chip 1 shown in the figure. Figure 15A and Figure 15B respectively represent Figure 13 the top view and the bottom view of the flow path substrate 12 of the inkjet head chip 1 shown in the figure. Figure 16 represents Figure 13 the top view of the silicon nozzle substrate 11 of the inkjet head chip 1 shown in the figure. Figures 17A to 18B are cross-sectional views obtained by cutting the inkjet head chip 1 shown in the figure along XVIIA-XVIIA, XVIIB-XVIIB, XVIIIA-XVIIIA, and XVIIIB-XVIIIB respectively Figure 13 shown in the figure.

[0200] The inkjet head chip 1 is a substantially quadrangular prism-shaped component that is long in the left-right direction and is formed by sequentially laminating the pressure chamber substrate 13, the flow path substrate 12, the silicon nozzle substrate 11, and the liquid-repellent film 14 ( Figures 13 to 18B ). It should be noted that in Figure 13 , the silicon nozzle substrate 11 and the liquid-repellent film 14 are not shown separately.

[0201] Figure 13 The inkjet head chip 1 shown in the figure is an inkjet head chip having a shear mode type pressure mechanism. The pressure chamber substrate 13 is provided with a supply flow path 131, an air chamber 132, a common circulation flow path 133, etc. (refer to Figure 13 , Figure 14A and Figure 14B etc.). A plurality of supply flow paths 131 and air chambers 132 are provided in an alternating arrangement in the left-right direction and are arranged in 4 columns in the front-rear direction. The supply flow path 131 has a substantially rectangular cross-section and is formed along the up-down direction, and has an inlet on the upper surface and an outlet on the lower surface of the pressure chamber substrate 13.

[0202] In addition, the upper end of the supply flow path 131 communicates with the ink storage portion 51 of the manifold 5, and ink is supplied from the ink storage portion 51 to the supply flow path 131, and the ink for ejection from the nozzle 111 is stored inside the supply flow path 131. It should be noted that the supply flow path 131 of the pressure chamber substrate 13 and the through-flow path 125 of the flow path substrate 12 together constitute the pressure chamber in the shear mode type pressure mechanism. In Figure 13 the inkjet head chip 1 shown in the figure, the pressure chamber straddles the supply flow path 131 of the pressure chamber substrate 13 and the through-flow path 125 of the flow path substrate 12 and is formed along the up-down direction in a substantially rectangular cross-section with the same area, and communicates with the nozzle 111 at the lower end (refer to Figure 17A , Figure 17B etc.).

[0203] The air chamber 132 is formed to have a substantially rectangular cross section slightly larger than that of the supply flow path 131 and is parallel to the supply flow path 131 in the vertical direction. In addition, unlike the supply flow path 131, the air chamber 132 is not connected to the ink storage unit 51, and ink does not flow into the air chamber 132. Further, the air chamber 132 is not connected to the nozzle 111 (refer to Figure 17A , Figure 17B etc.).

[0204] The supply flow path 131 and the air chamber 132 are formed by being separated by a partition wall 136 made of a piezoelectric material as a pressure generating member (refer to Figure 18A ). A driving electrode (not shown) is provided on the partition wall 136. When a voltage is applied to the driving electrode, the portion of the partition wall 136 between the adjacent supply flow paths 131 repeatedly undergoes shear mode displacement, thereby applying pressure to the ink in the supply flow path 131. It should be noted that, in the supply flow paths 131 shown in Figures 13 to 18B etc., the supply flow paths 131 located at the left and right ends having the partition wall 136 only on one side are not used, and the supply flow paths 131 having the partition wall 136 on both sides other than these are used.

[0205] It should be noted that the air chamber 132 may not be provided and only the supply flow path 131 may be formed, but as described above, it is preferable to alternately provide the supply flow path 131 and the air chamber 132. Thereby, the supply flow paths 131 can be made not adjacent to each other. Therefore, when the partition wall 136 adjacent to one supply flow path 131 deforms, it is possible not to affect other supply flow paths 131.

[0206] The common circulation flow path 133 is constituted by connecting a first common circulation flow path 134 and a second common circulation flow path 135 (refer to Figure 13 and Figure 14B etc.). The first common circulation flow path 134 is provided on the lower surface side of the pressure chamber substrate 13 and is arranged in three columns along the left - right direction on the front side, the rear side, and the central part thereof of the inkjet head chip 1 so as to avoid the portions where the supply flow path 131 and the air chamber 132 are provided.

[0207] In addition, on the lower surface side of the first common circulation flow path 134, a plurality of individual circulation flow paths 121 provided on the flow path substrate 12 are connected. The individual circulation flow path 121 is constituted by a connection portion 122 communicating with the through - flow path 125 and an extension portion 123 extending from the connection portion 122. Ink is discharged from the through - flow path 125 of the flow path substrate 12 via the connection portion 122 and from the extension portion 123, and can converge in the first common circulation flow path 134 ( Figure 14B , Figure 15A and Figure 17A , 17B)。In addition, the first common circulation flow path 134 is connected to a second common circulation flow path 135 that can discharge ink outside the inkjet head chip 1 near the right end portion. Therefore, the first common circulation flow path 134 becomes a flow path through which the ink flowing from the extension portion 123 of the individual circulation flow path 121 flows toward the second common circulation flow path 135.

[0208] The second common circulation flow path 135 is formed along the vertical direction in the same manner as the supply flow path 131. In addition, the lower surface side of the pressure chamber substrate 13 of the second common circulation flow path 135 communicates with the first common circulation flow path 134, and the upper surface side communicates with the discharge liquid chamber 57 of the manifold 5, becoming a flow path for discharging the ink flowing from the first common circulation flow path 134 upward (the side opposite to the side of the silicon nozzle substrate 11) to the outside of the inkjet head chip 1. In addition, the second common circulation flow path 135 is provided near the right end portion of the inkjet head chip 1 and communicates with the first common circulation flow path 134. In addition, by setting the second common circulation flow path 135 to have a larger volume than each of the supply flow paths 131, the discharge efficiency of the ink can be improved.

[0209] In the flow path substrate 12, there are formed: a through-flow path 125 that communicates with the supply flow path 131 of the pressure chamber substrate 13 and is formed along the vertical direction in a substantially rectangular cross-section having the same area as the supply flow path 131; and an individual circulation flow path 121 that branches from the through-flow path 125 (refer to Figure 17A and Figure 17B etc.). The through-flow path 125 of the flow path substrate 12 and the supply flow path 131 of the pressure chamber substrate 13 function together as a pressure chamber.

[0210] The individual circulation flow path 121 is composed of a connection portion 122 that communicates with the through-flow path 125 and an extension portion 123 that extends from the connection portion 122. The entrance of the connection portion 122 of the individual circulation flow path 121 is connected to the through-flow path 125, and the exit of the extension portion 123 is connected to the first common circulation flow path 134, becoming a flow path for discharging the ink in the through-flow path 125 to the first common circulation flow path 134. From the viewpoint of easily discharging bubbles, foreign substances, etc. together with the ink, it is preferable to provide at least two individual circulation flow paths 121 in each supply flow path 131. In addition, for example, as Figure 17A and Figure 17B shown, one individual circulation flow path 121 is provided in each of the front direction and the rear direction of the supply flow path 131, for a total of two. This can achieve the effect of easily discharging bubbles, foreign substances, etc. together with the ink, and the manufacturing efficiency is also high, so it is preferable.

[0211] The silicon nozzle substrate 11 has an ink flow path surface S1 and an ink ejection surface S2 facing the flow path surface S1, and has a nozzle 111 penetrating from the flow path surface S1 to the ejection surface S2. A flow path substrate 12 is joined to the flow path surface S1 of the silicon nozzle substrate 11, and a liquid-repellent film 14 is provided on the ejection surface S2 of the silicon nozzle substrate 11. The nozzles 111 provided in the silicon nozzle substrate 11 are arranged in a manner corresponding to the respective through-flow paths 125 of the flow path substrate 12. The structures of the silicon nozzle substrate 11 and the liquid-repellent film 14 can adopt, for example, the same structures as those in the above-described laminates 10A to 10D.

[0212] Here, Figure 13 the XVIIA-XVIIA cross-section ( Figure 17A ) and the XVIIB-XVIIB cross-section ( Figure 17B ) of the inkjet head chip 1 shown are equivalent to the cross-sections obtained by cutting the inkjet head chip 1 in which the pressure chamber substrate 13, the flow path substrate 12, the silicon nozzle substrate 11, and the liquid-repellent film 14 are laminated with a plane orthogonal to the flow path surface S1 of the silicon nozzle substrate 11 in a manner including the center of the nozzle 111 and the individual circulation flow path 121. In the inkjet head chip 1, in this cross-section, the positional relationship between each individual circulation flow path 121 and the nozzle 111 satisfies the above formula 1.

[0213] [Ink Circulation System]

[0214] The ink circulation system 8 is an ink supply member for generating a circulation flow of ink from the pressure chamber constituted by the supply flow path 131 and the through-flow path 125 in the inkjet head 100 to the common circulation flow path 131 via the individual circulation flow path 121. The ink circulation system 8 includes a supply sub-tank 81, a circulation sub-tank 82, a main tank 83, etc. ( Figure 19 ).

[0215] The supply sub-tank 81 is filled with ink for supplying to the ink storage unit 51 of the manifold 5 and is connected to the first ink port 53 through an ink flow path 84. The circulation sub-tank 82 is filled with ink discharged from the discharge liquid chamber 57 of the manifold 5 and is connected to the fourth ink port 56 through an ink flow path 85. In addition, the supply sub-tank 81 and the circulation sub-tank 82 are provided at different positions in the vertical direction (gravity direction) with respect to the nozzle surface of the inkjet head chip 1 (hereinafter, also referred to as "position reference surface"). Thereby, a pressure P1 based on the water level difference between the position reference surface and the supply sub-tank 81 and a pressure P2 based on the water level difference between the position reference surface and the circulation sub-tank 82 are generated. In addition, the supply sub-tank 81 and the circulation sub-tank 82 are connected through an ink flow path 86. Moreover, by the pressure applied by the pump 88, the ink can be returned from the circulation sub-tank 82 to the supply sub-tank 81.

[0216] The main tank 83 is filled with ink for supplying the sub-tank 81 for supply, and is connected to the sub-tank 81 for supply through the ink flow path 87. Moreover, the ink can be supplied from the main tank 83 to the sub-tank 81 for supply by the pressure applied by the pump 89.

[0217] In addition, by appropriately changing the ink filling amount in each sub-tank and the position of each sub-tank in the vertical direction (gravity direction), the pressure P1 and the pressure P2 can be adjusted. Moreover, by the pressure difference between the pressure P1 and the pressure P2, the ink in the inkjet head 100 can be circulated at an appropriate circulation flow rate. Thereby, bubbles, foreign matters, etc. generated in the inkjet head chip 1 can be removed, and clogging of the nozzles 111, ejection failure, etc. can be suppressed.

[0218] It should be noted that, as an example of the ink circulation system 8, a method of controlling the circulation of ink using the water level difference has been described, but as long as it is a structure capable of generating a circulation flow of ink, it can of course be appropriately changed.

[0219] [Manufacturing method of inkjet head]

[0220] The inkjet head of the present invention can be manufactured, for example, by a manufacturing method including the following first process to third process.

[0221] First process; a process of bonding the flow path substrate to the flow path surface of the silicon nozzle substrate

[0222] Second process; after the first process, a process of forming the liquid-repellent film by vapor deposition by disposing the vapor deposition source of the liquid-repellent film on the ejection surface side of the silicon nozzle substrate bonded to the flow path substrate

[0223] Third process; after the second process, a process of removing the liquid-repellent film formed on the formation surface of the through-flow path in the substrate main body from the flow path substrate side

[0224] And, after manufacturing a laminate in which a flow path substrate, a silicon nozzle substrate, and a liquid-repellent film are laminated by the above first process to third process, an inkjet head chip can be obtained by bonding a pressure chamber substrate to the flow path substrate side of the obtained laminate.

[0225] Hereinafter, with reference to Figures 20 to 22 , taking the case where the laminate 10D of the present invention is manufactured as a laminate in which a flow path substrate, a silicon nozzle substrate, and a liquid-repellent film are laminated, the first process to the third process will be described. In Figures 20 to 22 the symbols used, the same symbols as those used in the laminate 10D shown in Figure 7 mean the same as those in the case of the laminate 10D. Hereinafter, only the symbols required for explaining the manufacturing method will be used for the explanation.

[0226] (First process)

[0227] Figure 20 It is a cross-sectional view showing a laminate of the flow path substrate 12 and the silicon nozzle substrate 11 obtained in the first process.

[0228] The first process is a process of bonding the flow path substrate 12 having the through-flow path 125 and two individual circulation flow paths 121a and 121b formed thereon to the flow path surface S1 of the silicon nozzle substrate 11 having the nozzle 111 formed thereon.

[0229] The silicon nozzle substrate 11 is prepared, for example, by the following method. First, a silicon base substrate that becomes a base member is prepared. The base substrate is composed of a first support layer having a thickness of 200 μm or more, a BOX layer, and a silicon nozzle substrate layer. The silicon nozzle substrate layer is the layer that becomes the silicon nozzle substrate 11. Next, on the surface on the side of the silicon nozzle substrate layer of the base substrate (the surface that becomes the emission surface S2 of the silicon nozzle substrate 11), a resist pattern is provided using a mask corresponding to the position where the nozzle 111 is to be formed, and the nozzle 111 is formed by etching the nozzle hole. As the etching method, for example, reactive ion etching (RIE) based on the Bosch method that is easy to etch deeply is used. It should be noted that in the formation of the nozzle, laser drilling or sandblasting may also be used (used in combination).

[0230] Next, after providing a second support layer having a thickness of 200 μm or more, for example, on the surface on the side of the silicon nozzle substrate layer of the base substrate having the nozzle hole that becomes the nozzle 111 (the surface that becomes the emission surface S2 of the silicon nozzle substrate 11), the above-mentioned first support layer and BOX layer are removed, and the silicon nozzle substrate 11 with the second support layer exposed on the flow path surface S1 side can be obtained.

[0231] The flow path substrate 12 is obtained by forming the through-flow path 125 and two individual circulation flow paths 121a and 121b at the positions shown in Figure 10 and Figure 11 on the base substrate that becomes a base member by a known method. Thus, the flow path substrate 12 having the through-flow path 125 and two individual circulation flow paths 121a and 121b that are the flow paths of the ink and the substrate main body 12a having the formation surfaces (F1 to F3) of these flow paths is obtained.

[0232] The first process is carried out, for example, by bonding the flow path surface S2 of the silicon nozzle substrate 11 with the second support layer to the lower surface S3 of the substrate main body 12a of the flow path substrate 12 and then removing the second support layer. It should be noted that the use of the second support layer is particularly useful for protecting the silicon nozzle substrate 11 when the thickness of the silicon nozzle substrate 11 is about 10 to 100 μm. If necessary, the silicon nozzle substrate 11 and the flow path substrate 12 may be bonded without using the second support layer.

[0233] The bonding of the flow path substrate 12 and the silicon nozzle substrate 11 can be performed, for example, using a known adhesive. The adhesive can be appropriately selected from known adhesives according to the constituent materials of each substrate. Specifically, as the adhesive, a known epoxy-based adhesive or the like can be used. As a commercially available product of the epoxy-based adhesive, for example, Epotek 353ND (manufactured by Epoxy Technology) can be cited. Hereinafter, the laminate of the flow path substrate 12 and the silicon nozzle substrate 11 will be referred to as laminate La.

[0234] (Second process)

[0235] Figure 21 FIG. is a cross-sectional view of the laminate La with a liquid-repellent film obtained by forming a liquid-repellent film on the laminate La composed of the flow path substrate 12 and the silicon nozzle substrate 11 obtained in the first process through the second process.

[0236] The second process is a process of forming the liquid-repellent film 14 by vapor deposition by disposing a vapor deposition source of the liquid-repellent film 14 on the ejection surface S2 side of the silicon nozzle substrate 11 in the laminate La. It should be noted that, in Figure 21 , regarding the liquid-repellent film, the liquid-repellent film to be removed in the third process is denoted as the liquid-repellent film 14x, and the liquid-repellent film formed on the ejection surface S2 side of the silicon nozzle substrate 11 that is not removed after the third process is denoted as the liquid-repellent film 14. That is, in the second process, the liquid-repellent film 14x is formed together with the liquid-repellent film 14.

[0237] As the liquid-repellent film 14, for example, a liquid-repellent film composed of a fluoropolymer layer can be cited. Hereinafter, the case of forming a liquid-repellent film composed of a fluoropolymer layer will be described as an example, but the liquid-repellent film is not limited thereto, and a known liquid-repellent film can be used.

[0238] As the vapor deposition source of the liquid-repellent film, the liquid-repellent agent described above can be used. As Figure 21 shown, the vapor deposition of the liquid-repellent agent in the second process is performed from the ejection surface S2 side of the silicon nozzle substrate 11. Through vapor deposition, the liquid-repellent agent adheres to the ejection surface S2 of the silicon nozzle substrate 11 and the inner wall surface (formation surface) of the nozzle 111, and enters the inside of the flow path substrate 12 from the nozzle 111 and adheres to the inner wall surface of the substrate main body 12a.

[0239] As described in the laminate 10D, the positional relationship between the inlet of the connection portion 122a of the individual circulation flow path 121a and the nozzle 111 satisfies Equation 1. Figure 21The evaporation source is schematically shown. The evaporation source is, for example, a heatable container containing a liquid repellent agent. By moving the heated container containing the liquid repellent agent in the front-rear direction, or by moving the laminate La on the container in the front-rear direction, the entire ejection surface S2 of the silicon nozzle substrate 11 of the laminate La is vapor-deposited. In Figure 21 In the positional relationship between the laminate La and the container in, the state in which, when the liquid repellent agent is vapor-deposited, the vapor of the liquid repellent agent travels from both ends of the container into the interior of the flow path substrate 12 via the end portion Ai on the ejection surface S2 side of the nozzle 111 and the end portion Bi on the flow path surface S2 side and the state in which it travels from the end portion Aii on the ejection surface S2 side of the nozzle 111 via the end portion Bii on the flow path surface S2 side into the interior of the flow path substrate 12 are indicated by the dotted arrows.

[0240] As Figure 21 shown, in the flow path substrate 12, the liquid repellent agent does not adhere to the inner wall surface below the position Y at a height of L×tanφ from the ejection surface S2, but adheres to the inner wall surface above it. Specifically, it adheres to the inner wall surface above the position Y on the formation surface F1 of the through-flow path 125 in the substrate main body 12a.

[0241] Moreover, afterwards, by performing treatments such as drying and curing on the adhered liquid repellent agent, as Figure 21 shown, a liquid repellent film 14x is formed at the portion where the liquid repellent agent is adhered. Similarly, as Figure 21 shown, liquid repellent films 14x and 14 are formed from the liquid repellent agent adhered to the ejection surface S2 of the silicon nozzle substrate 11 and the inner wall surface (formation surface) of the nozzle 111. In addition, since the entire inlets of the connection portions 122a and 122b of the individual circulation flow paths 121a and 121b are located below the position Y at a height of L×tanφ, the liquid repellent agent does not adhere to the formation surface F2 of the connection portions 122a and 122b of the individual circulation flow paths 121a and 121b in the substrate main body 12a and the portion of the flow path surface S1 corresponding to the lower surface of the connection portions 122a and 122b, and no liquid repellent film is formed. Also, the vapor of the liquid repellent agent does not reach the extension portions 123a and 123b of the individual circulation flow paths 121a and 121b, and no liquid repellent film is formed on the formation surface F3 of the extension portions 123a and 123b.

[0242] Drying and curing are usually carried out by heating. Appropriate conditions are determined according to the type of the liquid repellent agent, etc., and heat treatment is carried out at normal temperature or at a high temperature state (for example, 300 to 400 °C) as needed. Afterwards, in order to remove unreacted raw materials, for example, raw material fluoropolymers, it is preferable to perform cleaning (rinsing) using a fluorine-based solvent (such as hydrofluoroether), and it is more preferable to perform this cleaning using ultrasonic cleaning.

[0243] It should be noted that the liquid-repellent film 14 preferably has a base layer containing a silicon compound between its formed surface and the fluoropolymer layer. The formation of the base layer is carried out between the above-mentioned first process and the second process. The base layer is formed by a known method such as vapor deposition or sputtering according to the type of constituent material. The formation range of the base layer is at least the range where the liquid-repellent film 14 is formed. The base layer may also be formed, as required, on a surface outside the range where the liquid-repellent film 14 is formed, such as the formed surface of the nozzle 111 of the silicon nozzle substrate 11 or a part or the whole of the inner wall surface of the flow path substrate 12.

[0244] (Third process)

[0245] Figure 22 It is a cross-sectional view showing the laminate 10D obtained by removing the liquid-repellent film 14x from the laminate La with the liquid-repellent film obtained in the second process.

[0246] The third process is as follows: After the second process, the liquid-repellent film 14x formed on the formation surface F1 of the through-flow path 125 formed in the substrate main body 12a is removed from the upper surface S4 side of the flow path substrate 12. In Figure 22 , the liquid-repellent film 14x is removed by irradiating oxygen plasma from the upper surface S4 side of the flow path substrate 12. At this time, the liquid-repellent film 14x formed on the formation surface of the nozzle 111 of the silicon nozzle substrate 11 is also removed. In this method, the liquid-repellent film 14 formed on the emission surface S2 of the silicon nozzle substrate 11 is not removed.

[0247] As a method of removing only the liquid-repellent film 14x while leaving the liquid-repellent film 14, in addition to oxygen plasma irradiation, UV ozone irradiation etc. can also be cited. These methods are carried out by irradiating active rays with rectilinear progression, and therefore, the above-mentioned selective removal of the liquid-repellent film can be carried out.

[0248] In the method of irradiating active rays with rectilinear progression, the irradiation cannot reach the part overlapping with the substrate main body 12a when viewed from the upper side of the flow path substrate 12. Therefore, assuming that a liquid-repellent film is formed on the formation surface F2 of the connection parts 122a, 122b of the individual circulation flow paths 121a, 121b and the part of the flow path surface S1 corresponding to the lower surface of the connection parts 122a, 122b, it is almost impossible to remove the liquid-repellent film by this method. In Figure 21In the cross section shown, as described above, a liquid-repellent film is not formed on the formation surfaces F2 of the connection portions 122a and 122b of the individual circulation channels 121a and 121b and on the portions of the flow path surfaces S1 corresponding to the lower surfaces of the connection portions 122a and 122b. Therefore, by irradiating the upper side of the flow path substrate 12 with actinic rays having linear progressivity, substantially all of the liquid-repellent film formed on the inner wall surface of the flow path substrate 12 can be removed. In addition, the liquid-repellent film formed on the formation surface of the nozzle 111 can also be removed by this method.

[0249] Thus, as Figure 22 shown in the cross section, a laminate 10D having a liquid-repellent film 14 formed only on the ejection surface S2 of the silicon nozzle substrate 11 can be obtained.

[0250] Industrial Applicability

[0251] According to the present invention, it is possible to provide an inkjet head and a method for manufacturing an inkjet head. In an inkjet head including a silicon nozzle substrate having a liquid-repellent film on the ejection surface side and a flow path substrate having a circulation channel, the formation of the liquid-repellent film inside the flow path substrate is suppressed, whereby the ink ejection performance is excellent. In the method for manufacturing an inkjet head, the formation of the liquid-repellent film inside the flow path substrate during manufacturing is suppressed. In addition, it is possible to provide an inkjet recording apparatus including an inkjet head having excellent ink ejection performance.

[0252] Explanation of Reference Numerals

[0253] 1 Inkjet head chip

[0254] 11 Silicon nozzle substrate

[0255] 111 Nozzle

[0256] 12 Flow path substrate

[0257] 12a Substrate main body

[0258] 121 Individual circulation channel

[0259] 122 Connection portion

[0260] 123 Extension portion

[0261] 125 Through-flow channel

[0262] 10A, 10B, 10C, 10D Laminates of liquid-repellent film, silicon nozzle substrate, and flow path substrate

[0263] 13 Pressure chamber substrate

[0264] 131 Supply channel

[0265] 132 Air chamber

[0266] 126, 133 Common circulation channel

[0267] 134 First common circulation passage

[0268] 135 Second common circulation passage

[0269] 136 Partition wall

[0270] 14 Liquid repellent film

[0271] 5 Manifold

[0272] 8 Ink circulation system

[0273] 100 Inkjet head

[0274] 200 Inkjet recording apparatus

Claims

1. An inkjet head, the inkjet head having: A silicon nozzle substrate having a flow path surface for ink and an ejection surface for ink facing the flow path surface, and having nozzles penetrating from the flow path surface to the ejection surface; A flow path substrate that is joined to the flow path surface of the silicon nozzle substrate and has a flow path for ink and a substrate body forming the flow path; And A liquid-repellent film that is provided on the ejection surface of the silicon nozzle substrate, Wherein The flow path substrate has a through-flow path and n individual circulation flow paths as the flow paths for the ink. The through-flow path penetrates the substrate body facing the nozzle. The n individual circulation flow paths communicate with the through-flow path and extend in a direction away from the nozzle. And the n individual circulation flow paths have a portion that overlaps with the substrate body when viewed from above on the side opposite to the surface of the flow path substrate joined to the silicon nozzle substrate. The positional relationship between each of the individual circulation flow paths and the nozzle satisfies the following formula 1: L×tanφ>H1 Formula 1 In Formula 1, each symbol represents the following meanings in a cross-section obtained by cutting the silicon nozzle substrate and the flow path substrate with a plane orthogonal to the flow path surface of the silicon nozzle substrate in a manner that includes the center of the nozzle and the individual circulation flow path: φ: The angle formed by the straight line connecting the first nozzle end on the side of the ejection surface away from the individual circulation flow path and the second nozzle end on the side of the flow path surface close to the individual circulation flow path with the ejection surface. L: The distance from the straight line passing through the first nozzle end and orthogonal to the ejection surface to the intersection point of the formation surface of the through-flow path and the formation surface of the individual circulation flow path in the substrate body that is the farthest from the flow path surface. H1: The distance from the ejection surface to the intersection point of the formation surface of the through-flow path and the formation surface of the individual circulation flow path in the substrate body that is the farthest from the flow path surface.

2. The inkjet head according to claim 1, wherein, The inkjet head has a structure in which the diameter of the nozzle gradually decreases from the flow path surface toward the ejection surface. The φ in Formula 1 is the maximum angle among the angles formed by the straight line connecting the first nozzle end and the end on the side of each section close to the individual circulation flow path on the flow path surface with the ejection surface.

3. The inkjet head according to claim 1 or 2, wherein, At least two of the individual circulation flow paths are located on a straight line passing through the center of the nozzle on the flow path surface. The centers of the nozzle and the through-flow path coincide. In a cross-section obtained by cutting with a plane orthogonal to the flow path surface of the silicon nozzle substrate in a manner that includes the centers of the nozzle and the through-flow path and the two individual circulation flow paths, the two individual circulation flow paths are in a symmetric relationship. The positional relationship between the individual circulation flow paths, the through-flow path, and the nozzle satisfies the following formula 2: (W-D2) / (D1+D2)×t>H2 Formula 2 D1: The diameter of the nozzle on the ejection surface D2: The diameter of the nozzle on the flow path surface t: The thickness of the silicon nozzle substrate H2: The distance from the flow path surface to the intersection point of the formation surface of the through-flow path and the formation surface of the individual circulation flow path in the substrate body that is the farthest from the flow path surface. W: The width of the through-flow path.

4. The inkjet head according to claim 1 or 2, wherein, The liquid-repellent film is formed by vapor deposition.

5. The inkjet head according to claim 1 or 2, wherein, The silicon nozzle substrate and the flow path substrate are joined by an adhesive.

6. The inkjet head according to claim 1 or 2, wherein, The liquid-repellent film is composed of a base layer containing a silicon compound and a fluoropolymer layer sequentially provided from the silicon nozzle substrate side.

7. The inkjet head according to claim 1 or 2, wherein, The thickness of the silicon nozzle substrate is in the range of 10 to 100 μm.

8. A method for manufacturing an inkjet head, manufacturing the inkjet head according to any one of claims 1 to 7, wherein, The method for manufacturing the inkjet head includes: A first step in which the flow path substrate is joined to the flow path surface of the silicon nozzle substrate in the first step; A second step in which, after the first step, in the second step, an evaporation source of the liquid-repellent film is disposed on the ejection surface side of the silicon nozzle substrate joined to the flow path substrate and the liquid-repellent film is formed by evaporation; and A third step in which, after the second step, in the third step, the liquid-repellent film on the formation surface of the through-flow path formed in the substrate body is removed from the flow path substrate side.

9. The manufacturing method of an inkjet head according to claim 8, wherein, In the removal of the liquid-repellent film, UV ozone irradiation or oxygen plasma irradiation is performed from the flow path substrate side to the formation surface of the through-flow path of the substrate body.

10. An inkjet recording apparatus, wherein, The inkjet recording apparatus includes the inkjet head according to any one of claims 1 to 7.

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