Inkjet head

Abstract

The present invention addresses the problem of providing an inkjet head comprising an actuator having high long-term reliability. This inkjet head includes an actuator comprising a layered substrate obtained by joining a plurality of substrates using an adhesive layer. The actuator includes: an ink flow path that enables communication among the plurality of substrates; and a protective film that is formed between the ink flow path and the layered substrates and covers at least the surface of the adhesive layer. The protective film includes a first layer, a second layer, and a third layer in order from the layered substrate side toward the ink flow path. The first layer is made of a first organic thin film, the second layer is made of an inorganic thin film, and the third layer is in contact with the ink flow path and made of a second organic thin film.

Description

[Technical Field]

[0001] The present invention relates to an inkjet head, and more particularly to an inkjet head having an actuator with high long-term reliability. [Background technology]

[0002] The actuator included in an inkjet head is manufactured by bonding, with an adhesive layer, substrates such as a pressure chamber substrate having a pressure chamber that stores ink and applies pressure to the ink to eject it, and a flow path substrate having an ink flow path that introduces ink into the pressure chamber. In such actuators, if each substrate has a metal material such as an electrode, contact with highly corrosive water-based ink can corrode the metal material of the substrate, leading to failure of the actuator. Therefore, a technology is known that ensures the long-term reliability of the inkjet head by forming a protective film on the ink-contacting portion.

[0003] In particular, in inkjet heads equipped with a shear mode actuator that ejects ink by deforming the partition wall of the pressure chamber (e.g., made of a piezoelectric element), the role that the protective film plays in ensuring long-term reliability is extremely important because metal electrodes are present in the partition wall of the pressure chamber.

[0004] In such actuators, a highly chemical-resistant organic protective film, such as polyparaxylylene (parylene), has been used as a protective film to protect the substrate from water-based ink. However, actuators using organic protective films such as polyparaxylylene have a problem: when an electrical signal pulse is applied to a piezoelectric element for a long period of time to eject ink, the ink gradually stops ejecting from the pressure chamber, causing the inkjet head to break down. The ink does not eject due to small defects in the protective film, particularly those in the area in contact with the adhesive layer, which allow ink to penetrate into the actuator substrate and reach the metal electrodes, resulting in a disconnection.

[0005] One known example of an attempt to suppress the occurrence of the above-mentioned microdefects is to form a protective film with multiple layers. For example, Patent Document 1 describes a structure in which protective films made of two types of polyparaxylylene are laminated. Furthermore, Patent Document 2 describes a laminated structure in which an electrodeposited insulating layer is formed as a first layer on the metal electrode of a piezoelectric element, and an organic insulating layer is formed as a second layer on top of that. While the techniques described in Patent Documents 1 and 2 are expected to suppress the occurrence of microdefects to a certain extent, they do not sufficiently suppress the occurrence of microdefects in the protective film in contact with the adhesive layer, and therefore cannot sufficiently suppress failures due to the long-term application of the above-mentioned electrical signal pulses.

[0006] Also disclosed are actuators with laminated structures in which a first inorganic insulating layer is formed on a metal electrode, and a second organic insulating layer is formed on top of that (see, for example, Patent Documents 3 and 4). However, with the techniques described in these patent documents, it is known that in structures in which an adhesive layer is present, the growth of the inorganic insulating layer in the area in contact with the adhesive layer is inhibited by volatile components and the like, making it difficult to apply the techniques to actuators laminated with adhesive layers. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-71451 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-122684 [Patent Document 3] Special Publication No. 2019-508285 [Patent Document 4] Japanese Patent Application Laid-Open No. 2010-214895 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in view of the above problems and circumstances, and an object of the present invention is to provide an inkjet head equipped with an actuator that has high long-term reliability. [Means for solving the problem]

[0009] In the course of investigating the causes of the above problems in order to solve them, the present inventors discovered that in an actuator including an ink flow path, a laminated substrate formed by bonding multiple substrates with an adhesive layer, and a protective film between the ink flow path and the laminated substrate, the protective film can be configured to have, in order from the laminated substrate side toward the ink flow path, a first organic thin film, an inorganic thin film, and a second organic thin film, with the second organic thin film being in contact with the ink flow path, thereby achieving the present invention. That is, the above problems according to the present invention are solved by the following means.

[0010] 1. An inkjet head including an actuator having a laminated substrate in which a plurality of substrates are bonded with an adhesive layer, the actuator has an ink flow path that communicates between the plurality of substrates, and a protective film that covers at least a surface of the adhesive layer that is formed between the ink flow path and the laminated substrate, The protective film is formed from the laminated substrate side. The aforementioned Ink flow path side The first layer, the second layer, and the third layer are provided in this order. the first layer is made of a first organic thin film, the second layer is made of an inorganic thin film, The third layer is a layer that contacts the ink flow path and is made of a second organic thin film. the law of nature, The first organic thin film and the second organic thin film contain polyparaxylylene or a derivative thereof, and the inorganic thin film contains an oxide of a metal selected from aluminum, silicon, titanium, hafnium, and tantalum. Inkjet head.

[0013] 2 .An inkjet head as described in item 1, wherein the first layer and the second layer are in contact with each other.

[0014] 3.An inkjet head as described in item 1, wherein the first layer is in contact with the adhesive layer.

[0016] 4 .An inkjet head as described in item 1, wherein the thickness of the third layer is 3 μm or more.

[0017] 5 The plurality of substrates include a pressure chamber substrate and a flow channel substrate. 4 Item 1. The inkjet head according to any one of items 1 to 5.

[0018] 6 The pressure chamber substrate has a partition wall made of a piezoelectric material and an electrode formed on the surface of the partition wall, and the adhesive layer has conductivity. 5 Item 1. An inkjet head according to item 1. [Effects of the Invention]

[0019] The above-described means of the present invention make it possible to provide an inkjet head equipped with an actuator that has long-term reliability. The mechanism by which the effects of the present invention are exhibited or acted upon is presumed to be as follows.

[0020] An actuator included in an inkjet head typically includes a laminated substrate formed by bonding and stacking multiple substrates, with ink channels formed to connect the substrates. The substrates are bonded together using, for example, an adhesive layer made of an adhesive, and the surfaces (side surfaces) of the adhesive layer in the thickness direction, along with the ink channel-forming surfaces (wall surfaces) of the substrates, face the ink channels. The present invention relates to technology for a protective film formed on the surface of the laminated substrate facing the ink channels in the actuator.

[0021] As described above, it is known that micro-defects occur in the organic protective film, particularly in the portion that contacts the adhesive layer of the laminated substrate (hereinafter also referred to as "on the adhesive layer"), causing defects. The inventors hypothesized that the surface of the laminated substrate that contacts the ink flow path is a unique portion where multiple materials exist, including the substrate, adhesive layer, and substrate, and therefore micro-defects are particularly likely to occur in the organic protective film on the adhesive layer. For example, they hypothesized that low-molecular-weight volatile components remaining in the adhesive in the adhesive layer are released during the formation of the organic protective film, inhibiting its growth and causing micro-defects.

[0022] Therefore, in the present invention, the protective film, particularly the protective film covering the adhesive layer, is configured to have the above-mentioned first, second and third layers from the surface of the laminated substrate toward the ink flow path, thereby sufficiently suppressing the penetration of ink into the laminated substrate and improving the long-term reliability of the actuator.

[0023] Specifically, by using an organic thin film for the first layer, which is closest to the laminate substrate (adhesive layer), the adhesive is less likely to affect film growth during film formation and the release of components that inhibit film growth in the second and subsequent layers is suppressed. However, if the first layer were an organic thin film, micro-defects caused by the adhesive layer would be more likely to occur. Therefore, a second layer made of an inorganic thin film was placed between the first and third layers to fill the origins of micro-defects that occur in the first layer, preventing micro-defects from continuing up to the third layer. Furthermore, by using an organic thin film for the third layer, which contacts the ink flow path, the third layer is ink-resistant and prevents the first and second layers from being altered by ink.

[0024] In this way, the present invention makes it possible to sufficiently prevent ink from penetrating into the laminated substrate and sufficiently protect, for example, the metal electrodes from the ink, thereby improving the long-term reliability of the actuator. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is a perspective view showing an example of an embodiment of an inkjet head according to the present invention; [Figure 2]Bottom view of the inkjet head shown in Figure 1 [Figure 3] Cross-sectional view of the lower part of the inkjet head shown in Figure 1, cut in the left-right direction [Figure 4] FIG. 2 is an exploded perspective view of the actuator and nozzle substrate of the inkjet head shown in FIG. 1. [Figure 5] Cross-sectional view along line VV in Figure 4 [Figure 6] Cross-sectional view along line VI-VI in Figure 5 [Figure 7] Partial cross-sectional view taken along line VII-VII in Figure 6 [Figure 8] Partial cross-sectional view taken along line VIII-VIII in Figure 6 [Figure 9] FIG. 10 is a partial cross-sectional view of another example of an inkjet head according to an embodiment of the present invention. [Figure 10] An enlarged cross-sectional view of a protective film covering the adhesive layer surface of the inkjet head shown in Figure 9. DETAILED DESCRIPTION OF THE INVENTION

[0026] The inkjet head of the present invention includes an actuator having a laminated substrate formed by bonding multiple substrates with an adhesive layer, the actuator having an ink flow path connecting the multiple substrates, and a protective film formed between the ink flow path and the laminated substrate and covering at least the surface of the adhesive layer, the protective film having, in order from the laminated substrate side toward the ink flow path, a first layer, a second layer, and a third layer, the first layer being made of a first organic thin film, the second layer being made of an inorganic thin film, and the third layer being a layer in contact with the ink flow path and made of a second organic thin film. This feature is a technical feature common to or corresponding to each of the following embodiments.

[0027] In an embodiment of the present invention, the first organic thin film or the second organic thin film preferably contains polyparaxylylene or a derivative thereof. It is more preferable that both the first organic thin film and the second organic thin film contain polyparaxylylene or a derivative thereof. Polyparaxylylene and its derivatives are preferable in that they can be formed into a film by, for example, a vapor deposition method, have excellent permeability into fine structures, and can fully and uniformly permeate deep into the fine structures even after the formation of ink flow paths.

[0028] In an embodiment of the present invention, from the viewpoint of further exhibiting the effects of the present invention, it is preferable that the first layer and the second layer are in contact with each other, and it is also preferable that the first layer is in contact with the adhesive layer.

[0029] In an embodiment of the present invention, from the viewpoint of more effectively exhibiting the effects of the present invention, the inorganic thin film preferably contains an oxide of a metal selected from aluminum, silicon, titanium, hafnium, and tantalum.

[0030] In an embodiment of the present invention, from the viewpoint of further exhibiting the effects of the present invention, the thickness of the third layer is preferably 3 μm or more.

[0031] In one embodiment of the present invention, the plurality of substrates include a pressure chamber substrate and a flow channel substrate.

[0032] An embodiment of the present invention is an inkjet head in which the pressure chamber substrate comprises a partition wall made of a piezoelectric body and an electrode formed on the surface of the partition wall, and the adhesive layer is conductive.

[0033] The present invention, its components, and embodiments for carrying out the present invention will be described in detail below. In this application, the symbol "to" is used to mean that the numerical values ​​before and after it are included as lower and upper limits.

[0034] [Inkjet head] The inkjet head of the present invention includes an actuator having a laminated substrate formed by bonding multiple substrates with an adhesive layer, wherein the actuator has an ink flow path connecting the multiple substrates and a protective film formed between the ink flow path and the laminated substrate and covering at least the surface of the adhesive layer. In the inkjet head of the present invention, the protective film has, in order from the laminated substrate side toward the ink flow path, a first layer, a second layer, and a third layer, the first layer being made of a first organic thin film, the second layer being made of an inorganic thin film, and the third layer being a layer in contact with the ink flow path and made of a second organic thin film.

[0035] Preferred embodiments of the present invention will be described below with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples. The components shown in these drawings can be modified as appropriate without departing from the spirit of the present invention. For the sake of convenience, the present specification defines the direction in which ink is ejected from the inkjet head as "downward" and the direction opposite to the "downward" as "upward." Furthermore, arrows in the ink flow paths in the drawings indicate the direction in which ink flows.

[0036] FIG. 1 is a perspective view showing an example of an embodiment of an inkjet head of the present invention, and FIG. 2 is a bottom view of the inkjet head shown in FIG. 1. When recording on a recording medium, the bottom surface of the inkjet head and the recording surface of the recording medium are positioned opposite each other. Specifically, the recording medium is positioned so that its recording surface is located below the inkjet head in a direction perpendicular to the direction in which ink is ejected, and inkjet recording is performed while the recording medium is transported. In the following description, for convenience, the direction in which the recording medium is transported is referred to as the front-to-rear direction, and the direction on the recording surface perpendicular to the direction in which the recording medium is transported is referred to as the left-to-right direction.

[0037] Fig. 3 is a cross-sectional view taken in the left-right direction of the lower part of the inkjet head shown in Fig. 1. Fig. 4 is an exploded perspective view of an actuator and a nozzle substrate of the inkjet head shown in Fig. 1. Fig. 5 is a cross-sectional view taken along line VV in Fig. 4, and Fig. 6 is a cross-sectional view taken along line VI-VI in Fig. 5. Figs. 7 and 8 are partial cross-sectional views taken along line VII-VII and line VIII-VIII in Fig. 6, respectively.

[0038] 1, 2, 3, etc., the inkjet head 100 of this embodiment includes an actuator 10A, a manifold 5 that stores ink to be supplied to the actuator 10A, and a nozzle plate 20 having nozzles 21A and 21B for ejecting ink from the actuator 10A to the outside of the inkjet head 100. The actuator 10A is a shear mode type actuator, and includes a laminated substrate in which a flow path substrate 3A, an adhesive layer 2, and a pressure chamber substrate 1A are laminated in this order from the manifold 5 side.

[0039] The actuator 10A has a laminated substrate that includes one flow path substrate and one pressure chamber substrate, which are bonded together with an adhesive layer. The actuator according to the present invention may have multiple flow path substrates and pressure chamber substrates, and may further include substrates other than the flow path substrates and pressure chamber substrates. In this case, an adhesive layer is present between at least one of the substrates, and at least the surface (side surface) of the adhesive layer facing the ink flow path is covered with the protective film according to the present invention.

[0040] The flow path substrate 3A included in the actuator 10A is a wiring substrate having wiring electrodes 33A and 33B (see FIG. 4), and the inkjet head 100 has, above the actuator 10A, a flexible substrate 8 (see FIG. 4) connected to the wiring electrodes of the flow path substrate 3A, and a drive circuit board (not shown) connected to the flexible substrate 8. The inkjet head 100 has a housing 6 that houses lower members (nozzle plate 20, actuator 10A, manifold 5, etc.), and a cover member 7 attached to the housing 6 so as to cover upper members (flexible substrate 8, drive circuit board, etc.).

[0041] The housing 6 is a member formed by die-casting, for example, from aluminum, and is formed long in the left-right direction. The bottom surface of the housing 6 has an opening so that the nozzle plate 20 is exposed to the outside. Mounting holes 68 are formed at both left and right ends of the housing 6, respectively, for mounting the housing 6 to the printer main body.

[0042] The lower end of the manifold 5 is attached and fixed by adhesive to the outer edge of the upper surface 3Sb of the flow path substrate 3A. The manifold 5 is a member molded from, for example, resin, and is disposed above the flow path substrate 3A of the actuator 10A. It functions to store ink to be supplied to the actuator 10A. Specifically, as shown in FIG. 3 and other figures, the manifold 5 is formed from, for example, a resin material and is elongated in the left-right direction. It includes a hollow main body 52 that forms the ink storage section 51 and first to third ink ports 53 to 55 that form the ink flow paths. The ink storage section 51 is further partitioned into two sections, an upper first liquid chamber 51a and a lower second liquid chamber 51b, by a filter F that removes foreign matter from the ink.

[0043] 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 section 51. A first joint 81a is fitted onto the tip 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 air bubbles inside the first liquid chamber 51a.

[0044] A second joint 81b is fitted onto the tip of the second ink port 54. The third ink port 55 is connected to the upper left end of the second liquid chamber 51b and is used to remove air bubbles from the second liquid chamber 51b. A third joint 82a is fitted onto the tip of the third ink port 55. The manifold 5 may further have a fourth ink port (not shown) as an ink outlet for discharging surplus ink that is not used in printing and is discharged from the actuator 10A to the outside of the inkjet head 100.

[0045] The nozzle plate 20 is disposed below the pressure chamber substrate 1A of the actuator 10A. The nozzle plate 20 is made primarily of, for example, silicon (Si), and has nozzles 21A and 21B that serve as ink ejection holes when ink is ejected from the pressure chamber substrate 1A toward a recording medium.

[0046] As shown in FIG. 4, the pressure chamber substrate 1A of the actuator 10A is a substantially rectangular prism-shaped member that is elongated in the left-right direction and has two channel rows, row A and row B. Here, the rear channel row shown in FIG. 4 is row A, and the front channel row is row B. Each channel row is composed of drive channels 11A, 11B and dummy channels 12A, 12B that are alternately arranged. The partition between adjacent drive channels 11A or 11B and dummy channels 12A or 12B is a drive wall 13 made of a piezoelectric material.

[0047] The piezoelectric material preferably contains a perovskite compound such as barium titanate (BaTiO3) and lead zirconate titanate ([Pb(Zr·Ti)O3], hereinafter also referred to as "PZT"), and preferably contains mainly PZT. The molar ratio of Zr to Ti in PZT is preferably Zr / Ti=30 / 70 to 70 / 30. "Containing mainly PZT" means that PZT accounts for 85 mass% or more of the total amount of the piezoelectric material.

[0048] To improve the performance of the piezoelectric material, donor ions may be added to PZT, and examples of donor ions include metal ions such as lanthanum (La), niobium (Nb), tantalum (Ta), tungsten (W), aluminum (Al), and strontium (Sr), and it is preferable to include one or more ions selected from the group consisting of La, Nb, Ta, and W. It is preferable to include one or more metal ions selected from the group consisting of iron (Fe), cobalt (Co), and manganese (Mn) as acceptor ions.

[0049] In this specification, a drive channel is a channel that serves as an ink flow path that ejects ink in accordance with image data during image recording. A dummy channel is a channel that never ejects ink, regardless of the image data. A dummy channel is not filled with ink because it does not need to eject ink. A dummy channel is usually filled with a gas such as air.

[0050] As shown in Fig. 4 and its cross-sectional view along line VV in Fig. 5, each of the drive channels 11A, 11B and each of the dummy channels 12A, 12B opens to the lower surface 1Sa and the upper surface 1Sb of the pressure chamber substrate 1A, respectively, and is straight across the lower surface 1Sa and the upper surface 1Sb, and is formed so that a cross section perpendicular to the thickness direction is rectangular, i.e., a quadrangular prism. Note that the cross-sectional view in Fig. 5 shows a cross section of the channel row B, but the cross section of the channel row A is similar, and in the following explanation, the channel rows A and B will be explained with reference to Fig. 5. The same applies to Figs. 6 to 8.

[0051] 5 and its cross-sectional view taken along line VI-VI in FIG. 6, a driving electrode 14 is formed on each of the four wall surfaces facing into each of the driving channels 11A, 11B and each of the dummy channels 12A, 12B. Furthermore, as shown in FIG. 6, a protective film 4 is formed on the entire surface of the driving electrode 14 facing into the driving channels 11A, 11B, and is made up of a first layer 41, a second layer 42, and a third layer 43 laminated in this order from the driving electrode 14 side toward the driving channels 11A, 11B side.

[0052] The protective film 4 has the same three-layer structure as above, and is formed on the entire wall surface of the flow path substrate 3A facing the through holes 32A and 32B and on the entire wall surface of the adhesive layer 2 facing the through holes. The detailed structure of the protective film 4 will be described later. The through holes 32A and 32B (first ink flow path) of the flow path substrate 3A, the through holes of the adhesive layer 2, and the drive channels 11A and 11B (second ink flow path) are connected to each other, forming an ink flow path for the actuator 10A.

[0053] Connection electrodes 15A and 15B are formed on the upper surface 1Sb of the pressure chamber substrate 1A so as to correspond one-to-one to the drive channels 11A and 11B and the dummy channels 12A and 12B. One end of each connection electrode 15A and 15B is electrically connected to the drive electrode 14 in the corresponding drive channel 11A, 11B or dummy channel 12A, 12B.

[0054] The actuator 10A is an independently driven actuator in which drive channels 11A, 11B and dummy channels 12A, 12B are alternately arranged in each channel row of the pressure chamber substrate 1A, and shear deformation is caused in the drive wall 13 by applying a drive signal of a predetermined voltage to the drive electrode 14. This applies a pressure change for ejection to the ink supplied into the drive channels 11A, 11B, causing it to be ejected as ink droplets from the nozzles 21A, 21B of the nozzle plate 20 bonded to the lower surface of the actuator 10A, i.e., the lower surface 1Sa of the pressure chamber substrate 1A.

[0055] Nozzles 21A and 21B are formed in the nozzle plate 20 at positions corresponding to the drive channels 11A and 11B of the pressure chamber substrate 1A. Since ink is not ejected from the dummy channels 12A and 12B, the nozzle plate 20 does not have nozzles at positions corresponding to the dummy channels 12A and 12B. Therefore, the openings below the dummy channels 12A and 12B are blocked by the nozzle plate 20.

[0056] The other ends of the connection electrodes 15A corresponding to the drive channels 11A and dummy channels 12A in row A extend from within each channel 11A, 12A toward one edge of the upper surface 1Sb of the pressure chamber substrate 1A and terminate at a distance of approximately 200 μm from the edge. The other ends of the connection electrodes 15B corresponding to the drive channels 11B and dummy channels 12B in row B extend from within each channel 11B, 12B toward row A and terminate at a distance of approximately 200 μm from the channel row A. Therefore, all of the connection electrodes 15A, 15B extend in the same direction from the channels 11A, 11B, 12A, and 12B.

[0057] The driving electrode 14 and the connection electrodes 15A and 15B are made of a conductive material. Specific examples of the conductive material include conductive materials containing one or more metals such as platinum (Pt), gold (Au), copper (Cu), palladium (Pd), ruthenium (Ru), titanium (Ti), nickel (Ni), aluminum (Al), chromium (Cr), tungsten (W), and iridium (Ir). The conductive material may be a material containing one or more of these metals. The conductive material may be a mixture or alloy of metals. In this case, the conductive material may be a mixture or alloy of at least one of the above metals with another metal.

[0058] The flow path substrate 3A is a flat substrate having a lower surface 3Sa and an upper surface 3Sb that have areas larger than the area of ​​the upper surface 1Sb of the pressure chamber substrate 1A. The flow path substrate 3A has a bonding region 31 (shown by a dashed line in FIG. 4) on the lower surface 3Sa bonded to the upper surface 1Sb of the pressure chamber substrate 1A via an adhesive layer 2. After bonding, at least one end of the flow path substrate 3A extends outside the bonding region 31 to which the pressure chamber substrate 1A is bonded, and protrudes significantly to the side in the direction in which the channel rows of the pressure chamber substrate 1A are arranged.

[0059] The bonding region 31 is the region covered by the pressure chamber substrate 1A to which the lower surface 3Sa of the flow path substrate 3A is bonded, and is defined by a line extending downward from the outer periphery of the upper surface 1Sb of the pressure chamber substrate 1A to the flow path substrate 3A.

[0060] The flow path substrate 3A may be made of any suitable material such as glass, ceramics, silicon, plastic, etc. Among these, glass is preferred because it has appropriate rigidity, is inexpensive, and is easy to process.

[0061] The flow path substrate 3A is bonded via an adhesive layer 2 so as to cover the openings of all channels located on the upper surface 1Sb of the pressure chamber substrate 1A in a bonding region 31. Within the bonding region 31 of the pressure chamber substrate 1A in the flow path substrate 3A, through holes 32A and 32B are individually opened only at positions corresponding to the drive channels 11A and 11B of the pressure chamber substrate 1A, for supplying ink to each of the drive channels 11A and 11B from the upper surface 3Sb side of the flow path substrate 3A.

[0062] Each of the through holes 32A, 32B is formed so that the opening on the pressure chamber substrate 1A side, i.e., the opening on the lower surface 3Sa of the flow path substrate 3A, is the same size and shape as the opening of each of the drive channels 11A, 11B on the flow path substrate 3A side, i.e., the opening on the upper surface 1Sb of the pressure chamber substrate 1A. In the actuator 10A, each of the through holes 32A, 32B in the flow path substrate 3A has a cross-sectional shape that widens from the lower surface 3Sa toward the upper surface 3Sb of the flow path substrate 3A.

[0063] On the other hand, in the flow path substrate 3A, such through holes are not formed in the portions corresponding to the dummy channels 12A and 12B of the pressure chamber substrate 1A, and therefore the openings above the dummy channels 12A and 12B (on the flow path substrate 3A side) are blocked by the flow path substrate 3A.

[0064] On the surface (lower surface) 3Sa of the flow channel substrate 3A, which is the bonding surface with the pressure chamber substrate 1A, wiring electrodes 33A and 33B are formed in one-to-one correspondence with the connection electrodes 15A and 15B arranged on the upper surface 1Sb of the pressure chamber substrate 1A. The wiring electrode 33A corresponds to each connection electrode 15A in the channel row A, and the wiring electrode 33B corresponds to each connection electrode 15B in the channel row B. The wiring electrodes 33A and 33B are made of a conductive material. Examples of the conductive material include the same conductive materials as described above.

[0065] 4, one end of the wiring electrode 33A reaches the vicinity of the corresponding drive channel 11A and dummy channel 12A and overlaps the corresponding connection electrode 15A in a plan view seen from above, while the other end extends toward the rear end of the flow path substrate 3A that protrudes laterally from the pressure chamber substrate 1A. Furthermore, one end of the wiring electrode 33B reaches the vicinity of the corresponding drive channel 11B and dummy channel 12B and overlaps the corresponding connection electrode 15B in a plan view seen from above, while the other end passes between adjacent drive channels 11A in row A of channel array, straddles row A of channel array A, and extends toward the rear end of the flow path substrate 3A, similar to the wiring electrode 33A. Therefore, the wiring electrodes 33A and 33B are alternately arranged side by side from the inside of the bonding region 31 to the rear end on the underside 3Sa of the flow path substrate 3A that protrudes laterally from the pressure chamber substrate 1A.

[0066] A flexible substrate 8, which is an example of an external wiring member, is connected to the rear end of the flow path substrate 3A via, for example, an ACF (anisotropic conductive film) or the like, and electrically connects it to a drive circuit (not shown). As a result, a drive signal of a predetermined voltage from the drive circuit is applied to the drive electrodes 14 in each of the channels 11A, 11B, 12A, and 12B via the flexible substrate 8, the wiring electrodes 33A and 33B of the flow path substrate 3A, and the connection electrodes 15A and 15B of the pressure chamber substrate 1A.

[0067] The wiring electrodes 33A and 33B, which extend from the bonding region 31 of the flow path substrate 3A to the rear end, are covered with an insulating film 34 having a predetermined width outside the bonding region 31. The edge 34a of the insulating film 34 on the bonding region 31 side is formed linearly along the rear edge of the bonding region 31 so as to contact the rear edge, as shown in FIG. 4 . The width of the insulating film 34 preferably extends from the outside of the bonding region 31 to the connection position with the flexible substrate 8. Covering the wiring electrodes 33A and 33B near the bonding region 31 with the insulating film 34 in this manner prevents short-circuiting between the wiring electrodes 33A and 33B due to overflow of a conductive adhesive, contamination of the wiring electrodes 33A and 33B, and short-circuiting due to the adhesion of ink, etc., when a conductive adhesive is used as the adhesive, as in the actuator 10A. Examples of materials for the insulating film 34 include TiO2, SiO2, and Al2O3.

[0068] The adhesive layer 2 that bonds the pressure chamber substrate 1A and the flow path substrate 3A has through holes that connect the drive channels 11A, 11B of the pressure chamber substrate 1A to the through holes 32A, 32B of the flow path substrate 3A. The through holes have openings on the pressure chamber substrate 1A side that are the same size and shape as the openings on the upper surface 1Sb of the drive channels 11A, 11B, and openings on the flow path substrate 3A side that are the same size and shape as the openings on the lower surface 3Sa of the through holes 32A, 32B.

[0069] In the actuator 10A, the adhesive layer 2 is a conductive adhesive layer made of a conductive adhesive. The conductive adhesive layer 2 enables electrical connection between the connection electrodes 15A, 15B of the pressure chamber substrate 1A and the wiring electrodes 33A, 33B of the flow channel substrate 3A, which are bonded via the adhesive layer 2. The thickness of the adhesive layer 2 is preferably in the range of 0.1 to 5 μm, for example.

[0070] The conductive adhesive may be, for example, an adhesive in which conductive particles are dispersed. Examples of the adhesive include a room temperature curing adhesive that cures at room temperature, a heat curing adhesive that cures by accelerating polymerization when heated, and an active energy ray curing adhesive that cures by irradiating active energy rays such as ultraviolet rays.

[0071] Among these, thermosetting adhesives are preferred. Thermosetting adhesives are preferred because when heated to a predetermined temperature for curing after bonding, the viscosity of the adhesive temporarily decreases, making it easier to flow, and ensuring uniformity in the thickness of the resulting adhesive layer. Epoxy adhesives are preferably used as thermosetting adhesives, but are not particularly limited thereto.

[0072] The conductive particles include metal particles such as Au or Ni particles themselves, as well as synthetic resin particles whose surfaces are coated with a metal film such as Au or Ni by plating or the like, and either can be used in the present invention.

[0073] In the actuator 10A, a driving electrode is formed on the wall surface of the partition wall of the pressure chamber substrate facing each channel, and the adhesive constituting the adhesive layer as described above is a conductive adhesive to electrically connect the driving electrode to the wiring electrode of the flow path substrate. However, in the actuator according to the present invention, the driving electrode does not necessarily have to be formed on the wall surface of the partition wall facing each channel, as long as it is arranged to drive the partition wall. In other words, the adhesive layer may not necessarily be required to be conductive. In such cases, the adhesive layer may be formed, for example, with an adhesive that does not contain conductive particles in the above-mentioned conductive adhesive.

[0074] Next, the configuration of the protective film 4 of the actuator 10A will be described in detail with reference to FIGS. 5 to 8. As described above, FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. FIGS. 7 and 8 are partial cross-sectional views taken along line VII-VII and line VIII-VIII in FIG. 6, respectively. The cross-sectional views shown in FIGS. 7 and 8 are of the upper surface of the actuator 10A, that is, the portion extending from the upper surface 3Sb of the flow path substrate 3A through the adhesive layer 2 to the top of the pressure chamber substrate 1A (the driving wall 13 and the driving electrode 14).

[0075] 5, the protective film 4 is formed on the entire wall surface of the laminated substrate facing the ink flow path that connects the laminated substrate formed by bonding the flow path substrate 3A and the pressure chamber substrate 1A with the adhesive layer 2. The wall surface facing the ink flow path of the laminated substrate is made up of the wall surfaces facing the ink flow path of the flow path substrate 3A, the adhesive layer 2, and the pressure chamber substrate 1A.

[0076] The protective film 4 shown in FIGS. 6 to 8 has a configuration in which a first layer 41, a second layer 42, and a third layer 43 are laminated in this order from the laminate substrate side toward the ink flow path. The first layer 41 is made of a first organic thin film, the second layer 42 is made of an inorganic thin film, and the third layer is made of a second organic thin film. In the actuator according to the present invention, the protective film may have an optional layer between the laminate substrate and the first layer, between the first layer and the second layer, and between the second layer and the third layer. Such optional layers include, for example, inorganic oxide layers, such as a silicon dioxide (SiO) layer or an aluminum oxide (AlO) layer, which improve adhesion.

[0077] The first organic thin film constituting first layer 41 can be made of a material containing a resin capable of being formed into a thin film. The thickness of first layer 41 is preferably 1 μm or more, more preferably 3 μm or more, from the viewpoint of suppressing the release of volatile components from the adhesive that constitutes adhesive layer 2. The upper limit of the thickness of first layer 41 is preferably 15 μm or more, more preferably 10 μm, from the viewpoint of not inhibiting the displacement of driving wall 13.

[0078] Specifically, the resin capable of forming a thin film is preferably one or more selected from polyparaxylylene or its derivatives, polyimide, etc. The resin preferably contains polyparaxylylene or its derivatives, and is preferably a resin consisting only of polyparaxylylene or its derivatives. As the first organic thin film, a thin film consisting only of polyparaxylylene or its derivatives is particularly preferred.

[0079] A thin film made of polyparaxylylene or its derivatives is called a parylene film, and can be formed by a vapor phase synthesis method using a dimer (solid) of paraxylylene or its derivatives as a deposition source, the so-called CVD (Chemical Vapor Deposition) method.

[0080] Specifically, a parylene film can be formed according to the following chemical reaction formula. In the formula, (I) represents the chemical structural formula of a dimer (hereinafter also referred to as dimer (I)) of paraxylylene or a derivative thereof (hereinafter referred to as paraxylylene compound (A)). In the formula, (II) represents the chemical structural formula of the stable diradical of paraxylylene compound (A) generated by vaporizing and thermally decomposing dimer (I) and the paraxylylene compound (A). In the formula, (II) represents a state in which the diradical of paraxylylene compound (A) and the paraxylylene compound (A) reversibly coexist. In the formula, (III) represents the chemical structural formula of a polymer of paraxylylene compound (A) (hereinafter also referred to as polymer (III)) obtained by adsorbing and polymerizing the diradical of paraxylylene compound (A) onto a substrate. In this way, polymer (III) is formed as a thin film (parylene film) on the substrate, i.e., on the surface of the wall surface or the like of a laminate substrate constituting an actuator in this invention.

[0081] The parylene film is preferably formed by a CVD method, since the diradical of the stable paraxylylene compound (A) generated by vaporizing and thermally decomposing the dimer (I) has excellent permeability into fine structures and can penetrate sufficiently uniformly deep into the fine structures of the wall surface of the laminate substrate after the ink flow path is formed.

[0082] [ka]

[0083] In the above formula, R represents a hydrogen atom, or an atom or substituent substituted for a hydrogen atom. The four Rs bonded to each benzene ring may be the same or different. When all four Rs bonded to the benzene ring are hydrogen atoms, the paraxylylene compound (A) is paraxylylene. n represents the degree of polymerization.

[0084] Specific examples of R other than a hydrogen atom include a halogen atom such as fluorine, chlorine, or bromine, an alkyl group, etc. Preferred paraxylylene compounds (A) for the first organic thin film include paraxylylene in which four R are hydrogen atoms, monochloroparaxylylene in which one R is a chlorine atom and three R are hydrogen atoms, and dichloroparaxylylene in which two R are chlorine atoms and two R are hydrogen atoms.

[0085] Hereinafter, polyparaxylylene will be referred to as Parylene N, polymonochloroparaxylylene as Parylene C, and polydichloroparaxylylene as Parylene D. Dimers such as paraxylylene, monochloroparaxylylene, and dichloroparaxylylene, which are the raw materials for Parylene N, Parylene C, Parylene D, etc., can be obtained from Daisan Kasei Co., Ltd., etc. The thickness of the parylene film can be controlled by adjusting the film formation conditions and the amount of raw material input.

[0086] The surface of the first layer 41, for example, the first layer 41 made of a parylene film, may be subjected to an oxidation treatment. The oxidation treatment method may be appropriately selected from laser irradiation treatment, UV / ozone treatment, plasma irradiation treatment, etc. Plasma irradiation treatment is preferred as the oxidation treatment method. The oxidation treatment introduces hydrophilic groups such as carboxyl groups and hydroxyl groups into the surface of the parylene film, making it possible to uniformly increase the critical surface tension of the film. It is also possible to impart minute irregularities to the surface of the parylene film. This improves the adhesion between the first layer 41 and the second layer 42, thereby improving the durability of the actuator and the manufacturing yield.

[0087] The inorganic thin film constituting the second layer 42 may be made of an inorganic material capable of forming an inorganic thin film, particularly a dense inorganic thin film. By using an inorganic thin film, particularly a dense inorganic thin film, for the second layer, even if a micro-defect occurs in the first layer 41, the starting point of the defect can be filled.

[0088] The inorganic thin film can be formed by, for example, chemical vapor deposition (CVD), molecular layer deposition (MLD), atomic layer deposition (ALD), etc. From the viewpoint of low-temperature film formation and the denseness of the resulting film, the inorganic thin film is preferably formed by atomic layer deposition (ALD).

[0089] Inorganic materials suitable for the inorganic thin film include metal oxides, metal nitrides, metal carbides, and allotropes of carbon such as diamond-like carbon (DLC). Among these inorganic materials, metal oxides are preferred, and oxides of metals selected from aluminum, silicon, titanium, hafnium, magnesium, zirconium, and tantalum are more preferred, and oxides of metals selected from aluminum, silicon, titanium, hafnium, and tantalum are particularly preferred.

[0090] The metal oxide may be a composite oxide of two or more metals selected from the above metals. Furthermore, the inorganic material constituting the inorganic thin film may be a mixture of multiple metal oxides. Specific examples of metal oxides include SiO2, Al2O3, TiO2, ZrO2, MgO, Ta2O5, and HfO2, with SiO2, Al2O3, TiO2, Ta2O5, and HfO2 being preferred.

[0091] To form an inorganic thin film, particularly a metal oxide film, by atomic layer deposition (ALD), a precursor is first vaporized and adsorbed onto the substrate surface, in this case, the surface of the first layer 41, and then the precursor is exposed to an oxidizing gas to form a metal oxide thin film. The film formation is carried out in a vacuum chamber.

[0092] For example, precursors of Al2O3 include trimethylaluminum (TMA), dimethylaluminum isopropoxide (DMAIP), and dimethylaluminum hydride (DMAH).

[0093] Examples of precursors for SiO2 include tetraethoxysilane (TEOS; Si(OC2H5)4) and hexamethyldisilazane (HMDS; (CH3)3Si-NH-Si(CH3)3), while examples of precursors for TiO2 include tetrakis(dimethylamino)titanium (TDMAT; Ti[N(CH3)2]4) and TiCl4. Examples of precursors for HfO2 include tetrakis(ethylmethylamido)hafnium (TEMAH; Hf[N(CH3)(C2H5)]4), while examples of precursors for ZrO2 include tetrakis(ethylmethylamido)zirconium (TEMAZ; Zr[N(CH3)(C2H5)]4). Examples of precursors for Ta2O5 include tetrachlorotantalum (TaCl4). Examples of oxidizing agents include water (HO), ozone (O3), and O2 plasma.

[0094] In the formation of inorganic thin films using atomic layer deposition (ALD), the film thickness can be adjusted by repeating a cycle consisting of precursor adsorption and precursor oxidation by an oxidizing agent. The inorganic thin film formed in one cycle is usually a monolayer-level film.

[0095] The inorganic thin film constituting the second layer 42 may be a single layer film or a multilayer film. An example of a multilayer film is a multilayer film formed by stacking single layers made of a metal oxide, such as a metal oxide selected from SiO2, Al2O3, TiO2, Ta2O5, and HfO2. When the inorganic thin film is a multilayer film, it is preferable that the number of layers be at most two. A two-layer structure preferably includes a layer that improves adhesion and a layer that does not cause microdefects (a layer with high barrier properties).

[0096] The multilayer film may be, for example, a multilayer film formed by laminating a first metal oxide film and a second metal oxide film in this order from the first layer 41 side. The metal oxide constituting the first metal oxide film is preferably Al2O3 or the like. The metal oxide constituting the second metal oxide film is preferably TiO2 or the like. For example, a combination of an Al2O3 film as the first metal oxide film and a TiO2 film as the second metal oxide film is preferable for the multilayer film.

[0097] From the viewpoints of burying the starting points of microdefects and durability, the thickness of the second layer 42 is preferably in the range of 5 to 500 nm, more preferably in the range of 20 to 100 nm, as a total thickness. When the inorganic thin film is made up of multiple films, it is preferable to adjust the thickness of each film so that the total thickness is in the above range.

[0098] The second organic thin film constituting third layer 43 can be made of a material containing a resin capable of being formed into a thin film. The thickness of third layer 43 is preferably 1 μm or more, more preferably 3 μm or more, from the viewpoint of protecting the inorganic thin film layer from contact with ink. The upper limit of the thickness of third layer 43 is preferably 15 μm, more preferably 10 μm, from the viewpoint of not inhibiting the displacement of driving wall 13.

[0099] The second organic thin film can have the same configuration as the first organic thin film, except for the thickness. The second organic thin film is preferably a thin film made solely of polyparaxylylene or a derivative thereof. Specifically, an organic thin film made of parylene N, parylene C, or parylene D is preferred. The third layer 43, for example, the third layer 43 made of a parylene film, may be subjected to an oxidation treatment on its surface, similar to the first layer 41. Because the third layer 43 is in contact with the ink flow path, the oxidation treatment improves the wettability of the parylene film or the like with respect to aqueous ink, thereby enabling stable ink ejection.

[0100] The shear mode actuator and the inkjet head of the present invention having the same have been described above using actuator 10A as an example. Below, an inkjet head of the present invention having a bend mode actuator will be described with reference to Figures 9 and 10.

[0101] Fig. 9 is a partial cross-sectional view of another example of an embodiment of an inkjet head according to the present invention. Fig. 9 shows an actuator 10B in the inkjet head and a nozzle plate 20 laminated on the actuator 10B. The actuator 10B is a bend-mode actuator. Fig. 10 is an enlarged cross-sectional view of a portion surrounded by a dotted line in a protective film that covers the surface of the laminated substrate, including the adhesive layer surface, facing the ink flow path, in the actuator 10B of the inkjet head shown in Fig. 9.

[0102] The actuator 10B includes a flow path substrate 3B, which is formed by laminating, from top to bottom, a wiring substrate 3a, an adhesive layer 3d, a spacer substrate 3b, and a diaphragm 3v, an adhesive layer 2 located below the flow path substrate 3B, and a pressure chamber substrate 1B bonded to the flow path substrate 3B via the adhesive layer 2. The spacer substrate 3b has a hollow portion, and inside the hollow portion is a piezoelectric element, which is formed by laminating, from top to bottom, an upper electrode (driving electrode) 3e, a piezoelectric element 3P, and a lower electrode (driving electrode) 3f. The portion of the hollow portion other than the piezoelectric element is space 3S.

[0103] The upper electrode 3e of the piezoelectric element is connected to an external power supply by multiple wiring conductors E that are electrically connected from the spacer substrate 3b to the wiring substrate 3a. The lower electrode 3f is connected to the external power supply via a separate path. The piezoelectric element 3P is driven by applying a voltage via the upper electrode 3e and the lower electrode 3f. This causes the diaphragm 3v to bend downward.

[0104] The diaphragm 3v is bonded to the pressure chamber substrate 1B, which is placed below the piezoelectric element, via an adhesive layer 2. A nozzle plate 20 having nozzles 21 is disposed below the pressure chamber substrate 1B. The nozzle plate 20 can be made of the same material as the nozzle plate bonded to the actuator 10A.

[0105] The pressure chamber substrate 1B has pressure chambers (drive channels) 11 that contain ink, and nozzles 21 communicate with the pressure chambers 11. When the piezoelectric element is driven, the volume of the pressure chambers 11 decreases due to the curved vibration plate 3v, causing the ink contained in the pressure chambers 11 to be ejected from the nozzles 21.

[0106] The flow path substrate 3B and the adhesive layer 2 have through holes 32 that serve as ink flow paths that communicate with the pressure chambers 11 of the pressure chamber substrate 1B. Ink is supplied to the pressure chambers 11 from the upper side of the actuator 10B through the through holes 32. The ink flow paths in the actuator 10B are made up of the through holes 32 and the pressure chambers 11.

[0107] The wiring substrate 3a, spacer substrate 3b, and pressure chamber substrate 1B in the flow path substrate 3B of actuator 10B can be made of materials such as SUS, nickel, 42 alloy, and silicon (Si). The piezoelectric body constituting piezoelectric body 3P, the upper electrode (driving electrode) 3e, the lower electrode (driving electrode) 3f, and the conductive materials constituting wiring conductors can be the same materials as those described for actuator 10A. Adhesive layer 3d and adhesive layer 2 do not need to be conductive. Therefore, adhesives that do not contain conductive particles, etc., as described for actuator 10A, can be used.

[0108] As the diaphragm 3v, any general diaphragm used in a bend mode type actuator can be used without any particular restrictions.

[0109] In the actuator 10B, a protective film 4 is formed on the entire wall surfaces of the flow path substrate 3B, adhesive layer 2, and pressure chamber substrate 1B that face the ink flow path. As shown in Fig. 10, the protective film 4 is composed of, from the wall surface toward the ink flow path, a first layer 41, a second layer 42, and a third layer 43. The configurations of the first layer 41, second layer 42, and third layer 43 can be the same as those described for the actuator 10A above. [Example]

[0110] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0111] [Inkjet head manufacturing] For the actuator of the inkjet head KM1024i series manufactured by Konica Minolta, the protective film on the surface of the wall forming the ink flow path was replaced with a protective film having the configuration shown in Table I to obtain inkjet heads of each comparative example or example.

[0112] The inkjet head KM1024i is equipped with a shear-mode actuator, and the actuator configuration has a cross section similar to that shown in Figure 5. However, in the KM1024i, the actuator has a total of 1024 ink flow paths. As shown in Figure 5, the protective film is formed on the entire wall surface of the laminated substrate, which faces the ink flow paths that connect the laminated substrate, in which the flow path substrate and the pressure chamber substrate are bonded with an adhesive layer. The wall surface of the laminated substrate facing the ink flow paths is made up of the flow path substrate, the adhesive layer, and the wall surfaces of the pressure chamber substrate facing the ink flow paths.

[0113] Example 1 In Example 1, an organic thin film made of parylene C was formed as the first layer of the protective film on the wall surface of the laminate substrate facing the ink flow path using a parylene vapor deposition device (manufactured by SCS Corporation). Specifically, a monochloroparaxylylene dimer was used as the film-forming material, and the surface on which the protective film was to be formed (the entire surface of the wall surface) was exposed to vapor obtained by vaporizing the dimer at a film-forming pressure of 40 mTorr and room temperature (25°C), thereby forming the first layer of the protective film (thickness 1.0 μm).

[0114] Next, an inorganic thin film (consisting of two layers, Al2O3 and TiO2, from the first layer side) was formed on the first layer to form the second layer of the protective film. The inorganic thin film was deposited by ALD using a PICOSUN R-200 Advanced (equipment). The Al2O3 layer was deposited to a thickness of 40 nm on the first layer (Parylene C film) by cycles of alternating exposure to TMA and water at a deposition temperature of 100°C. The TiO2 layer was deposited to a thickness of 10 nm on the Al2O3 layer by cycles of alternating exposure to TDMAT and water at a deposition temperature of 100°C. The total thickness of the second layer was 0.05 μm (50 nm).

[0115] Furthermore, as the third layer of the protective film, an organic thin film made of parylene C was formed on the second layer in the same manner as the first layer, with a thickness of 3.8 μm.

[0116] (Comparative Example 1) As a protective film, an 8.9 μm thick organic thin film made of parylene C was formed on the wall surface of the laminated substrate facing the ink flow path in the same manner as the first layer in Example 1. The second and third layers were not formed.

[0117] (Comparative Example 2) As a protective film, a 5.0 μm thick organic thin film (first layer) made of parylene C was formed on the wall surface of the laminated substrate facing the ink flow path, in the same manner as the first layer in Example 1. A 4.5 μm thick organic thin film (second layer) made of parylene C was further formed on top of that. A third layer was not formed.

[0118] <Evaluation> A durability test was conducted under the following conditions using a reactive dye ink (cyan, genuine ink for the inkjet textile printer "Nassenger") manufactured by Konica Minolta. The results are shown in Table I.

[0119] <Drive conditions> Drive unit: Konica Minolta Inkjet Control System IJCS-1 Applied voltage: 17V Frequency: 40kHz Test temperature: Room temperature

[0120] <Evaluation method> After each pulse application count shown in Table I, it was checked whether electricity was flowing from the drive substrate to the partition walls (piezoelectric elements) of each ink flow path. If electricity was flowing to all 1024 ink flow paths, it was marked as "Good." If electricity was not flowing to even one of the 1024 ink flow paths, it was marked as "Poor."

[0121] [Table 1]

[0122] From Table I, it can be seen that the actuator in the ink jet head of the present invention has high long-term reliability. [Industrial Applicability]

[0123] According to the present invention, it is possible to provide an inkjet head equipped with an actuator that has high long-term reliability. [Explanation of symbols]

[0124] 100: Inkjet head 10A, 10B: Actuator 1A, 1B: Pressure chamber substrate 11, 11A, 11B: driving channel (second ink flow path) 12A, 12B: Dummy channels 13: Driving wall 14: Drive electrode 15A, 15B: Connection electrodes 2: Adhesive layer 3A, 3B: Channel board 31:Joint area 32, 32A, 32B: through holes (first ink flow paths) 33A, 33B: Wiring electrode 34: insulating film 3a: Wiring board 3b: Spacer substrate 3d:adhesive layer 3v: diaphragm 3e: Upper electrode (drive electrode) 3f: Lower electrode (drive electrode) 3P: Piezoelectric 3S: Space E: Wiring conductor 4:Protective film 41: 1st layer 42:Second layer 43:Third layer 5: Manifold 6: Housing 7: Cover material 8: Flexible board 20: Nozzle plate 21, 21A, 21B: Nozzle

Claims

1. An inkjet head including an actuator having a laminated substrate in which a plurality of substrates are bonded with an adhesive layer, the actuator has an ink flow path that communicates between the plurality of substrates, and a protective film that covers at least a surface of the adhesive layer that is formed between the ink flow path and the laminated substrate, the protective film includes a first layer, a second layer, and a third layer in this order from the laminated substrate side toward the ink flow path side, the first layer is made of a first organic thin film, the second layer is made of an inorganic thin film, the third layer is a layer in contact with the ink flow path and is made of a second organic thin film; The first organic thin film and the second organic thin film contain polyparaxylylene or a derivative thereof, and the inorganic thin film contains an oxide of a metal selected from aluminum, silicon, titanium, hafnium, and tantalum. Inkjet head.

2. The ink jet head according to claim 1 , wherein the first layer and the second layer are in contact with each other.

3. 2. The ink jet head according to claim 1, wherein the first layer is in contact with the adhesive layer.

4. 2. The ink jet head according to claim 1, wherein the third layer has a thickness of 3 [mu]m or more.

5. The inkjet head according to claim 1 , wherein the plurality of substrates include a pressure chamber substrate and a flow path substrate.

6. the pressure chamber substrate comprises a partition wall made of a piezoelectric material and an electrode formed on the surface of the partition wall; 6. The ink jet head according to claim 5, wherein the adhesive layer is electrically conductive.

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