Liquid discharge head and liquid discharge system

Abstract

To inhibit deterioration of performance of a protection film and a piezoelectric element in a liquid discharge head.SOLUTION: A liquid discharge head includes: a piezoelectric element in which a first driving electrode, a piezoelectric material, and a second driving electrode are laminated in a lamination direction; a sealing substrate which forms a sealing space provided with the piezoelectric element; a protection film formed on the piezoelectric material in the lamination direction; a humidity detection unit which is formed on the piezoelectric material in the lamination direction and has a first detection electrode, an interposition layer, and a second detection electrode. A water absorption rate of the protection film is lower than a water absorption rate of the interposition layer.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present disclosure relates to a liquid ejection head and a liquid ejection system. [Background technology]

[0002] A liquid ejection head is known that includes a piezoelectric actuator including a pressure chamber plate having a pressure chamber, a vibration plate that generates pressure in the pressure chamber, and a piezoelectric element formed on the vibration plate. For example, Patent Document 1 discloses that the piezoelectric actuator is covered by a case, and a humidity sensor is provided in the space inside the case. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-33834 A Summary of the Invention [Problem to be solved by the invention]

[0004] The performance of the piezoelectric actuator and its neighboring members may be degraded by the influence of humidity. Conventional techniques have not proposed a specific structure for employing a humidity sensor, such as the structure of the humidity sensor itself or the position of the humidity sensor relative to the piezoelectric actuator and its neighboring members, and therefore may not be able to properly obtain information about the humidity of the piezoelectric actuator and its neighboring members. Therefore, there is a demand for a technique for a liquid ejection head that can properly obtain information about the humidity of the piezoelectric actuator and its neighboring members and properly manage the influence of humidity using a simple structure. [Means for solving the problem]

[0005] According to one aspect of the present disclosure, there is provided a liquid ejection head, the liquid ejection head including a piezoelectric element having a first driving electrode, a piezoelectric body, and a second driving electrode stacked in a stacking direction, a sealing substrate forming a sealed space in which the piezoelectric element is provided, a protective film formed on the piezoelectric body in the stacking direction, and a humidity detection unit formed on the piezoelectric body in the stacking direction, the humidity detection unit having a first detection electrode, an intermediate layer, and a second detection electrode, the protective film having a lower water absorption rate than the intermediate layer. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is an explanatory diagram showing a schematic configuration of a liquid ejection device according to a first embodiment. [Diagram 2] FIG. 2 is a block diagram showing the functional configuration of the liquid ejection system. [Diagram 3] FIG. 2 is an exploded perspective view showing the configuration of a liquid ejection head. [Figure 4] FIG. 2 is an explanatory diagram showing the configuration of a liquid ejection head in a plan view. [Diagram 5] 5 is a cross-sectional view showing the VV position in FIG. 4. [Figure 6] FIG. 5 is an explanatory diagram showing an enlarged view of a portion of FIG. 4; [Figure 7] FIG. 7 is a cross-sectional view taken along the line VII-VII in FIG. 6 . [Figure 8] 7 is a cross-sectional view taken along line VII-VII of FIG. 6 in another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] A. First embodiment: FIG. 1 is an explanatory diagram showing a schematic configuration of a liquid ejection system 500 as a first embodiment of the present disclosure. In this embodiment, the liquid ejection system 500 is an inkjet printer that ejects ink, as an example of a liquid, onto a printing paper P to form an image. The liquid ejection system 500 may eject ink onto any type of medium, such as a resin film or fabric, instead of the printing paper P. X, Y, and Z shown in FIG. 1 and the figures following FIG. 1 represent three spatial axes that are mutually orthogonal. In this specification, the directions along these axes are also referred to as the X-axis direction, the Y-axis direction, and the Z-axis direction. When specifying the direction, the positive direction is represented as "+" and the negative direction is represented as "-", and the direction notation is made using both positive and negative signs, with the direction indicated by the arrow in each figure being the + direction and the opposite direction being the - direction. In this embodiment, the Z-axis direction coincides with the vertical direction, with the +Z direction representing the vertical downward direction and the -Z direction representing the vertical upward direction. Furthermore, in cases where the positive and negative directions are not specified, the description will be given assuming that the three X, Y, and Z are the X-axis, Y-axis, and Z-axis.

[0008] The liquid ejection system 500 includes a liquid ejection head 510, an ink tank 550, a transport mechanism 560, a movement mechanism 570, and a control device 580. The liquid ejection head 510 has a plurality of nozzles formed therein, and ejects a total of four colors of ink, for example, black, cyan, magenta, and yellow, in the +Z direction to form an image on a print paper P. The liquid ejection head 510 is mounted on a carriage 572, and moves back and forth in the main scanning direction together with the movement of the carriage 572. In this embodiment, the main scanning direction is the +X direction and the -X direction. The liquid ejection head 510 is not limited to the four colors, and may further eject any ink, such as light cyan, light magenta, clear, and white.

[0009] The ink tank 550 contains ink to be ejected from the liquid ejection head 510. The ink tank 550 is connected to the liquid ejection head 510 by a resin tube 552. The ink in the ink tank 550 is supplied to the liquid ejection head 510 via the tube 552. Note that instead of the ink tank 550, a bag-shaped liquid pack formed of a flexible film may be provided.

[0010] The transport mechanism 560 transports the print paper P in the sub-scanning direction. The sub-scanning direction is a direction that intersects with the X-axis direction, which is the main scanning direction, and in this embodiment, is the +Y direction and the -Y direction. The transport mechanism 560 includes a transport rod 564 to which three transport rollers 562 are attached, and a transport motor 566 that drives and rotates the transport rod 564. The transport motor 566 drives and rotates the transport rod 564, so that the print paper P is transported in the +Y direction, which is the sub-scanning direction. The number of transport rollers 562 is not limited to three, and may be any number. Also, a configuration may be provided with a plurality of transport mechanisms 560.

[0011] The movement mechanism 570 includes a carriage 572, a conveyor belt 574, a movement motor 576, and a pulley 577. The carriage 572 carries the liquid ejection head 510 in a state capable of ejecting ink. The carriage 572 is fixed to the conveyor belt 574. The conveyor belt 574 is stretched between the movement motor 576 and the pulley 577. The movement motor 576 is driven to rotate, so that the conveyor belt 574 moves back and forth in the main scanning direction. As a result, the carriage 572 fixed to the conveyor belt 574 also moves back and forth in the main scanning direction.

[0012] Fig. 2 is a block diagram showing the functional configuration of the liquid ejection system 500. Some components of the liquid ejection system 500, such as an ink tank 550, a transport mechanism 560, and a moving mechanism 570, are omitted in Fig. 2. As shown in Fig. 2, the liquid ejection head 510 includes a piezoelectric element 300, a humidity detection mechanism 200, and a temperature detection mechanism 400.

[0013] The piezoelectric element 300 is a drive element that generates a pressure change in the ink in the pressure chamber of the liquid ejection head 510. The humidity detection mechanism 200 functions as a so-called electrical humidity sensor.

[0014] As shown in FIG. 2, the humidity detection mechanism 200 includes a humidity detection unit 210, a humidity detection power supply unit 230, and a humidity detection resistance measurement unit 240. In this embodiment, the humidity detection unit 210 is configured as a resistance detection type humidity sensor, and utilizes the property that the conductivity of the measurement target changes with moisture absorption. The humidity detection power supply unit 230 is, for example, a constant current circuit, and flows a predetermined current to the humidity detection unit 210 under the control of the humidity management unit 250. The humidity detection resistance measurement unit 240 detects the electrical resistance value of the humidity detection unit 210 based on the current value of the current that the humidity detection power supply unit 230 flows to the humidity detection unit 210 and the voltage value of the voltage generated in the humidity detection unit 210. The detection result by the humidity detection resistance measurement unit 240 is output to the humidity management unit 250. The humidity detection power supply unit 230 may be a circuit that applies a predetermined voltage to the humidity detection unit 210. The humidity detection power supply unit 230 and the humidity detection resistance measurement unit 240 may be provided in the control device 580.

[0015] The temperature detection mechanism 400 functions as a temperature sensor that detects the temperature of ink in a pressure chamber, which will be described later. The temperature detection mechanism 400 includes a temperature detection unit 410, a temperature detection power supply unit 430, and a temperature detection resistor measurement unit 440. The temperature detection unit 410 is configured with conductive wiring including a resistor for temperature detection. The temperature detection power supply unit 430 is, for example, a constant current circuit, and passes a predetermined current to the temperature detection unit 410 under the control of the temperature management unit 450. The temperature detection resistor measurement unit 440 acquires the resistance value of the detection resistor of the temperature detection unit 410 based on the current value of the current passed by the temperature detection power supply unit 430 to the temperature detection unit 410 and the voltage value of the voltage generated in the temperature detection unit 410. The detection result by the temperature detection resistor measurement unit 440 is output to the temperature management unit 450.

[0016] As shown in FIG. 2, the control device 580 is configured as a microcomputer including a CPU 582 and a storage unit 584. The control device 580 is mounted on, for example, the wiring board 120 or a circuit board directly or indirectly connected to the wiring board 120. The storage unit 584 can be, for example, a non-volatile memory that can be erased by an electric signal such as an EEPROM, a non-volatile memory that can be erased by ultraviolet light such as a One-Time-PROM or an EPROM, or an inerasable non-volatile memory such as a PROM. Various programs for realizing the functions provided in this embodiment are stored in the storage unit 584. The CPU 582 functions as the head control unit 520, the humidity control unit 250, and the temperature control unit 450 by developing and executing the programs stored in the storage unit 584. The control device 580 may further include a communication unit for transmitting and receiving detection results of humidity or temperature to and from a predetermined server.

[0017] The head control unit 520 supervises the control of each unit of the liquid ejection head 510, such as the ejection operation. In addition to controlling the liquid ejection head 510, the head control unit 520 may also control, for example, the reciprocating operation of the carriage 572 in the main scanning direction and the transport operation of the printing paper P in the sub-scanning direction. As the ejection operation of the liquid ejection head 510, the head control unit 520 can control the ejection of ink onto the printing paper P by, for example, outputting a drive signal based on the temperature of the ink in the pressure chamber acquired from the temperature management unit 450 to the liquid ejection head 510 to drive the piezoelectric element 300.

[0018] The humidity management unit 250 derives information on the humidity of the detection target using the resistance value of the humidity detection unit 210 acquired from the humidity detection resistor measurement unit 240 and a humidity calculation formula stored in advance in the storage unit 584. The "information on humidity" includes, for example, the amount of moisture absorbed or desorbed by the member, the relative humidity and absolute humidity as the amount of moisture contained in the air, and the degree of influence on the performance of the member due to moisture absorption or desorption. The "degree of influence on the performance of the member" may include the presence or absence of a malfunction of the member, and the change in the performance of the member over time. In this embodiment, the humidity management unit 250 derives information on the humidity of the sealed space described later and outputs it to the head control unit 520. Note that the humidity management unit 250 is not limited to the information on the humidity of the sealed space, but may also derive information on the humidity of the piezoelectric body 70 described later and output it to the head control unit 520. The humidity calculation formula indicates the correspondence between the electrical resistance value of the detection target and the humidity. Instead of the humidity calculation formula, a conversion table indicating the correspondence between the electrical resistance value of the detection target and the humidity may be used. Furthermore, the correspondence relationship between the electrical resistance value of the detection target and the change over time in the performance of the detection target may be stored in the storage unit 584. The circuit constituting the humidity control unit 250 may be disposed on the wiring board 120, for example. This makes it possible to prevent the liquid ejection head 510 from becoming large.

[0019] The temperature management unit 450 derives the temperature of the ink in the pressure chamber 12 using the electrical resistance value of the detection resistor of the temperature detection unit 410 acquired from the temperature detection resistor measurement unit 440 and a temperature calculation formula previously stored in the memory unit 584. The electrical resistance value of the detection resistor changes depending on the temperature. The temperature calculation formula indicates the correspondence relationship between the electrical resistance value of the temperature detection resistor and the temperature. In other words, the temperature management unit 450 derives the temperature of the ink in the pressure chamber 12 by utilizing the characteristic that the electrical resistance value of the detection resistor changes depending on the temperature. Note that a conversion table indicating the correspondence relationship between the electrical resistance value of the temperature detection resistor and the temperature may be used instead of the temperature calculation formula. The temperature management unit 450 outputs the derived temperature of the ink in the pressure chamber 12 to the head control unit 520.

[0020] A detailed configuration of the liquid ejection head 510 will be described with reference to FIG. 3 to FIG. 5. FIG. 3 is an exploded perspective view showing the configuration of the liquid ejection head 510. FIG. 4 is an explanatory diagram showing the configuration of the liquid ejection head 510 in a plan view. In this disclosure, "plan view" means a state in which an object is viewed along a stacking direction described later. FIG. 4 shows the configuration of the pressure chamber substrate 10 and the diaphragm 50 of the liquid ejection head 510, and the protective film 82, the sealing substrate 30, the case member 40, etc. are omitted to facilitate understanding of the technology. FIG. 5 is a cross-sectional view showing the VV position of FIG. 4.

[0021] The liquid ejection head 510 includes the pressure chamber substrate 10, the communication plate 15, the nozzle plate 20, the compliance substrate 45, the vibration plate 50, the sealing substrate 30, the case member 40, the wiring substrate 120, and the piezoelectric element 300 shown in FIG. 4. The liquid ejection head 510 is formed by stacking these laminated members. In the present disclosure, the direction in which the laminated members forming the liquid ejection head 510 are stacked is also called the "stacking direction". In the present embodiment, the stacking direction coincides with the Z-axis direction. In the present disclosure, the +Z direction side with respect to a predetermined reference position is also called the "one side of the stacking direction" or the "lower side", and the -Z direction side is also called the "other side of the stacking direction" or the "upper side".

[0022] The pressure chamber substrate 10 is formed using, for example, a silicon substrate, a glass substrate, an SOI substrate, various ceramic substrates, etc. As shown in FIG. 4, a plurality of pressure chambers 12 are formed in the pressure chamber substrate 10. The ink flow paths formed in the pressure chamber substrate 10, such as the pressure chambers 12, are formed by anisotropically etching the pressure chamber substrate 10 from the surface on the +Z direction side. The pressure chambers 12 are formed in a substantially rectangular shape in which the length in the X-axis direction is longer than the length in the Y-axis direction in a plan view. However, the shape of the pressure chambers 12 is not limited to a rectangular shape, and may be a parallelogram, a polygon, a circle, an oval, etc. An oval shape means a shape in which both ends in the longitudinal direction are semicircular based on a rectangular shape, and includes a rounded rectangular shape, an elliptical shape, an egg shape, etc.

[0023] As shown in FIG. 4, the pressure chambers 12 are arranged in a predetermined direction in the pressure chamber substrate 10. In a plan view of the liquid ejection head 510 seen along the stacking direction, the direction in which the pressure chambers 12 are arranged is also referred to as the "arrangement direction". In this embodiment, the pressure chambers 12 are arranged in two parallel rows, with the Y-axis direction being the arrangement direction. In the example of FIG. 4, the pressure chamber substrate 10 is formed with two pressure chamber rows: a first pressure chamber row L1 having a first arrangement direction parallel to the Y-axis direction, and a second pressure chamber row L2 having a second arrangement direction parallel to the Y-axis direction. The first pressure chamber row L1 and the second pressure chamber row L2 are arranged on both sides of the wiring substrate 120. Specifically, the second pressure chamber row L2 is arranged on the opposite side of the first pressure chamber row L1 across the wiring substrate 120 in a direction intersecting the arrangement direction of the first pressure chamber row L1. A direction perpendicular to both the arrangement direction and the stacking direction is also referred to as the "intersecting direction". 4, the intersecting direction is the X-axis direction, and the second pressure chamber row L2 is arranged in the -X direction with respect to the first pressure chamber row L1, sandwiching the wiring substrate 120. All of the pressure chambers 12 do not necessarily need to be arranged in a straight line, and for example, the pressure chambers 12 may be arranged in a so-called staggered arrangement along the Y-axis direction, in which every other pressure chamber 12 is arranged in a staggered manner in the intersecting direction.

[0024] As shown in FIG. 3, a communication plate 15, a nozzle plate 20, and a compliance substrate 45 are laminated on the +Z direction side of the pressure chamber substrate 10. The communication plate 15 is a flat plate member using, for example, a silicon substrate, a glass substrate, an SOI substrate, various ceramic substrates, a metal substrate, or the like. Examples of metal substrates include a stainless steel substrate. The communication plate 15 is provided with a nozzle communication passage 16, a first manifold portion 17, a second manifold portion 18 shown in FIG. 5, and a supply communication passage 19. The communication plate 15 is preferably made of a material having a thermal expansion coefficient substantially the same as that of the pressure chamber substrate 10. This makes it possible to suppress warping of the pressure chamber substrate 10 and the communication plate 15 caused by the difference in thermal expansion coefficient when the temperatures of the pressure chamber substrate 10 and the communication plate 15 change.

[0025] 5, the nozzle communication passage 16 is a flow path that communicates between the pressure chambers 12 and the nozzles 21. The first manifold portion 17 and the second manifold portion 18 function as part of a manifold 100 that serves as a common liquid chamber to which the multiple pressure chambers 12 communicate. The first manifold portion 17 is provided so as to penetrate the communication plate 15 in the Z-axis direction. In addition, as shown in FIG. 5, the second manifold portion 18 is provided on the surface of the communication plate 15 on the +Z direction side, without penetrating the communication plate 15 in the Z-axis direction.

[0026] As shown in FIG. 5, the supply communication passage 19 is a flow path connected to the pressure chamber supply path 14 provided in the pressure chamber substrate 10. The pressure chamber supply path 14 is a flow path connected to one end of the pressure chamber 12 in the X-axis direction via the throttling portion 13. The throttling portion 13 is a flow path provided between the pressure chamber 12 and the pressure chamber supply path 14. The throttling portion 13 is a flow path whose inner wall protrudes beyond the pressure chamber 12 and the pressure chamber supply path 14 and is formed narrower than the pressure chamber 12 and the pressure chamber supply path 14. As a result, the flow path resistance of the throttling portion 13 is higher than the flow path resistance of the pressure chamber 12 and the pressure chamber supply path 14. With this configuration, even if pressure is applied to the pressure chamber 12 by the piezoelectric element 300 during ink ejection, it is possible to suppress or prevent the ink in the pressure chamber 12 from flowing back into the pressure chamber supply path 14. There are multiple supply communication passages 19, which are arranged along the Y-axis direction, i.e., the arrangement direction, and are provided individually for each pressure chamber 12. The supply communication passage 19 and the pressure chamber supply passage 14 connect the second manifold portion 18 to each pressure chamber 12 , and supply ink within the manifold 100 to each pressure chamber 12 .

[0027] The nozzle plate 20 is provided on the opposite side of the pressure chamber substrate 10 across the communication plate 15, that is, on the surface of the communication plate 15 in the +Z direction. The material of the nozzle plate 20 is not particularly limited, and may be, for example, a silicon substrate, a glass substrate, an SOI substrate, various ceramic substrates, or a metal substrate. Examples of metal substrates include stainless steel substrates. The material of the nozzle plate 20 may be an organic material such as polyimide resin. However, it is preferable that the nozzle plate 20 is made of a material having a thermal expansion coefficient substantially equal to that of the communication plate 15. This makes it possible to suppress warping of the nozzle plate 20 and the communication plate 15 caused by the difference in thermal expansion coefficient when the temperature of the nozzle plate 20 and the communication plate 15 changes.

[0028] A plurality of nozzles 21 are formed in the nozzle plate 20. Each nozzle 21 is connected to each pressure chamber 12 via a nozzle communication passage 16. As shown in Fig. 3, the plurality of nozzles 21 are arranged along the arrangement direction of the pressure chambers 12, i.e., the Y-axis direction. The nozzle plate 20 is provided with two nozzle rows in which the plurality of nozzles 21 are arranged. The two nozzle rows correspond to the first pressure chamber row L1 and the second pressure chamber row L2, respectively.

[0029] As shown in FIG. 5, the compliance substrate 45 is provided together with the nozzle plate 20 on the opposite side of the communication plate 15 from the pressure chamber substrate 10, that is, on the surface of the communication plate 15 in the +Z direction. The compliance substrate 45 is provided around the nozzle plate 20 and covers the openings of the first manifold portion 17 and the second manifold portion 18 provided in the communication plate 15. The compliance substrate 45 includes, for example, a sealing film 46 made of a flexible thin film, and a fixed substrate 47 made of a hard material such as metal. As shown in FIG. 5, the region of the fixed substrate 47 facing the manifold 100 is completely removed in the thickness direction to define the opening 48. Therefore, one surface of the manifold 100 is a compliance portion 49 sealed only by the sealing film 46.

[0030] 5, a vibration plate 50 and a piezoelectric element 300 are laminated on the side of the pressure chamber substrate 10 opposite the communicating plate 15, etc., i.e., on the -Z direction side of the pressure chamber substrate 10. The piezoelectric element 300 flexibly deforms the vibration plate 50 to cause a pressure change in the ink inside the pressure chamber 12. The piezoelectric element 300 is illustrated simply in FIG.

[0031] The vibration plate 50 is provided between the piezoelectric element 300 and the pressure chamber substrate 10. The vibration plate 50 is provided at a position closer to the pressure chamber substrate 10 side than the piezoelectric element 300, and includes an elastic film 55 having silicon oxide (SiO2), and an insulator film 56 having zirconium oxide (ZrO2) provided on the elastic film 55. The elastic film 55 constitutes the surface on the -Z direction side of the flow path of the pressure chamber 12, etc. Note that the vibration plate 50 may be composed of, for example, either the elastic film 55 or the insulator film 56, or may include other films other than the elastic film 55 and the insulator film 56. Examples of materials for the other films include silicon, silicon nitride, etc.

[0032] As shown in FIG. 3, a sealing substrate 30 having substantially the same size as the pressure chamber substrate 10 in plan view is bonded to the surface of the pressure chamber substrate 10 on the -Z direction side by adhesive or the like. The sealing substrate 30 may be bonded to a protective film 82 described later by adhesive. As shown in FIG. 5, the sealing substrate 30 includes a ceiling portion 30T, a wall portion 30W, a holding portion 31, and a through hole 32. The holding portion 31 is a space defined by the ceiling portion 30T and the wall portion 30W, and protects the active portion of the piezoelectric element 300 by accommodating the piezoelectric element 300. In this embodiment, the holding portion 31 is provided for each row of the piezoelectric element 300, and more specifically, two holding portions 31 corresponding to the first pressure chamber row L1 and the second pressure chamber row L2 are formed adjacent to each other. The through hole 32 penetrates the sealing substrate 30 along the Z axis direction. The through hole 32 is disposed between the two holding portions 31 in plan view, and is formed in a rectangular shape elongated along the Y axis direction. In addition, the space formed as the holding portion 31, which is formed by sealing the sealing substrate 30 from the external space by joining the sealing substrate 30 with an adhesive or the like as described above, corresponds to the "sealed space" in this disclosure.

[0033] 5, a case member 40 is fixed on the sealing substrate 30. The case member 40 forms a manifold 100, which communicates with the multiple pressure chambers 12, together with the communication plate 15. The case member 40 has approximately the same outer shape as the communication plate 15 in a plan view, and is joined so as to cover the sealing substrate 30 and the communication plate 15.

[0034] The case member 40 has a storage section 41, a supply port 44, a third manifold section 42, and a connection port 43. The storage section 41 is a space having a depth capable of storing the pressure chamber substrate 10, the vibration plate 50, and the sealing substrate 30. The third manifold section 42 is a space formed in the case member 40 near both ends of the storage section 41 in the X-axis direction. The third manifold section 42 is connected to the first manifold section 17 and the second manifold section 18 provided on the communication plate 15, thereby forming a manifold 100. The manifold 100 has a shape elongated in the Y-axis direction. The supply port 44 communicates with the manifold 100 and supplies ink to each manifold 100. The connection port 43 is a through hole communicating with the through hole 32 of the sealing substrate 30, and the wiring substrate 120 is inserted through the through hole.

[0035] 5, the liquid ejection head 510 takes in ink supplied from the ink tank 550 shown in Fig. 1 through the supply port 44 shown in Fig. 5, fills the internal flow paths from the manifold 100 to the nozzles 21 with ink, and then applies a voltage based on a drive signal to each of the piezoelectric elements 300 corresponding to the multiple pressure chambers 12. This causes the vibration plate 50 to bend and deform together with the piezoelectric elements 300, changes the volume of each pressure chamber 12, and increases the internal pressure, causing ink droplets to be ejected from each nozzle 21.

[0036] The configurations of the piezoelectric element 300, the humidity detection unit 210, and the temperature detection unit 410 will be described with reference to Figures 4, 5, 6, and 7 as appropriate. Figure 6 is an explanatory diagram showing an enlarged view of a part of the range AR in Figure 4. Figure 7 is a cross-sectional view showing the position VII-VII in Figure 6.

[0037] 7, the piezoelectric element 300 has a first drive electrode 60, a piezoelectric body 70, and a second drive electrode 80. The first drive electrode 60, the piezoelectric body 70, and the second drive electrode 80 are stacked in this order toward the −Z direction of the stacking direction. The piezoelectric body 70 is provided between the first drive electrode 60 and the second drive electrode 80 in the stacking direction.

[0038] As shown in FIG. 6, the first driving electrode 60 and the second driving electrode 80 are electrically connected to the wiring board 120 shown in FIG. 5 via driving wiring. The driving wiring includes a first driving wiring 91 that electrically connects the wiring board 120 and the first driving electrode 60, and a second driving wiring 92 that electrically connects the wiring board 120 and the second driving electrode 80. The first driving electrode 60 and the second driving electrode 80 apply a voltage corresponding to a driving signal to the piezoelectric body 70. The driving voltage is a voltage applied to the piezoelectric element 300 from the first driving electrode 60 and the second driving electrode 80 by the head control unit 520 to drive the piezoelectric element 300. A part of the piezoelectric element 300 where a piezoelectric distortion occurs in the piezoelectric body 70 when a voltage is applied between the first driving electrode 60 and the second driving electrode 80 is also called an active part.

[0039] A driving voltage that varies depending on the amount of ink ejected is applied to the first driving electrode 60, and a predetermined reference voltage is applied to the second driving electrode 80 regardless of the amount of ink ejected. When a voltage difference occurs between the first driving electrode 60 and the second driving electrode 80 due to application of the driving voltage and the reference voltage, the piezoelectric body 70 of the piezoelectric element 300 is deformed. Due to the deformation of the piezoelectric body 70, the vibration plate 50 is deformed or vibrated, and the volume of the pressure chamber 12 changes. As the volume of the pressure chamber 12 changes, pressure is applied to the ink contained in the pressure chamber 12, and the ink is ejected from the nozzle 21 via the nozzle communication passage 16.

[0040] In this embodiment, the first driving electrode 60 is an individual electrode provided for each of the pressure chambers 12. As shown in FIG. 7, the first driving electrode 60 is a lower electrode provided on the opposite side of the piezoelectric body 70 from the second driving electrode 80, that is, below the piezoelectric body 70. The first driving electrode 60 is formed to a thickness of, for example, about 80 nanometers. The first driving electrode 60 is formed of a conductive material such as a metal such as platinum (Pt), iridium (Ir), gold (Au), or titanium (Ti), or a conductive metal oxide such as indium tin oxide, abbreviated as ITO. The first driving electrode 60 may be formed by laminating a plurality of materials such as platinum (Pt), iridium (Ir), gold (Au), or titanium (Ti). In this embodiment, platinum (Pt) is used as the first driving electrode 60.

[0041] As shown in FIG. 4, the piezoelectric body 70 has a predetermined width in the X-axis direction and has a long rectangular shape along the arrangement direction of the pressure chambers 12, i.e., the Y-axis direction. The thickness of the piezoelectric body 70 is, for example, about 1000 to 4000 nanometers. The piezoelectric body 70 may be a crystal film having a perovskite structure, so-called perovskite crystal, made of a ferroelectric ceramic material that exhibits an electromechanical conversion effect and is formed on the first driving electrode 60. The material of the piezoelectric body 70 may be, for example, a ferroelectric piezoelectric material such as lead zirconate titanate (PZT), or a material to which a metal oxide such as niobium oxide, nickel oxide, or magnesium oxide is added. Specifically, lead titanate (PbTiO3), lead zirconate titanate (Pb(Zr,Ti)O3), lead zirconate (PbZrO3), lead lanthanum titanate ((Pb,La),TiO3), lead lanthanum zirconate titanate ((Pb,La)(Zr,Ti)O3), lead magnesium zirconium titanate (Pb(Zr,Ti)(Mg,Nb)O3), etc. can be used. In this embodiment, lead zirconate titanate (PZT) is used as the piezoelectric body 70.

[0042] The material of the piezoelectric body 70 is not limited to lead-based piezoelectric materials that contain lead, and lead-free piezoelectric materials that do not contain lead can also be used. Examples of lead-free piezoelectric materials include bismuth ferrate ((BiFeO3), abbreviated as "BFO"), barium titanate ((BaTiO3), abbreviated as "BT"), potassium sodium niobate ((K,Na)(NbO3), abbreviated as "KNN"), potassium sodium lithium niobate ((K,Na,Li)(NbO3)), potassium sodium lithium tantalate niobate ((K,Na,Li)(Nb,Ta)O3), bismuth potassium titanate ((Bi 1 / 2 K 1 / 2 )TiO3, abbreviated as "BKT"), sodium bismuth titanate ((Bi 1 / 2 Na 1 / 2 )TiO3, abbreviated as "BNT"), bismuth manganate (BiMnO3, abbreviated as "BM"), and complex oxides containing bismuth, potassium, titanium, and iron and having a perovskite structure (x[(Bi x K 1-x )TiO3]-(1-x)[BiFeO3], abbreviated as "BKT-BF"); complex oxides containing bismuth, iron, barium and titanium and having a perovskite structure ((1-x)[BiFeO3]-x[BaTiO3], abbreviated as "BFO-BT"); and those to which metals such as manganese, cobalt and chromium have been added ((1-x)[Bi(Fe 1-y M y )O3]-x[BaTiO3] (M is Mn, Co or Cr)).

[0043] As shown in FIG. 4, the second driving electrode 80 is a common electrode provided in common to the multiple pressure chambers 12. The second driving electrode 80 has a predetermined width in the X-axis direction and is provided extending along the arrangement direction of the pressure chambers 12, i.e., the Y-axis direction. As shown in FIG. 7, the second driving electrode 80 is an upper electrode provided on the opposite side of the piezoelectric body 70 from the first driving electrode 60, i.e., on the upper side of the piezoelectric body 70. As with the first driving electrode 60, the material of the second driving electrode 80 is a conductive material such as metals such as platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti), and conductive metal oxides such as indium tin oxide, abbreviated as ITO. The second driving electrode 80 may be formed by laminating multiple materials such as platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti). In this embodiment, iridium (Ir) is used as the second driving electrode 80.

[0044] As shown in FIG. 7, a protective film 82 is formed on one end 80b of the second drive electrode 80 on the −X direction side. The material of the protective film 82 is a material having electrical insulation and moisture barrier properties. For example, an oxide insulating film such as aluminum oxide or hafnia, or a polymer material film such as polyimide can be used for the protective film 82. When the protective film 82 is a photosensitive resin such as polyimide, a resist layer used in the manufacturing process can be used. In this embodiment, the protective film 82 is made of polyimide.

[0045] As shown in FIG. 6, the protective film 82 is disposed at the driving electrode end position overlapping with the end of the second driving electrode 80 in a plan view of the liquid ejection head 510, and is formed so as to cover one end 80b of the second driving electrode 80 and the surface of the piezoelectric body 70 as shown in FIG. 7. The protective film 82 covers the surface of the piezoelectric body 70, thereby protecting the piezoelectric body 70 from the outside air and moisture in the air. For this reason, the protective film 82 is preferably made of a material with low water vapor permeability. Furthermore, the protective film 82 covers the one end 80b, thereby suppressing or preventing peeling of the second driving electrode 80 from the one end 80b. Furthermore, the covering of the one end 80b can suppress the driving of the piezoelectric element 300 in the vicinity of the end of the active part of the piezoelectric element 300. As a result, for example, it is possible to suppress the occurrence of physical damage such as cracks in the members in the vicinity of the end of the active part, such as the joint between the vibration plate 50 and the pressure chamber substrate 10 and the vibration plate 50. For this reason, the protective film 82 is preferably made of a material with a large elastic modulus or Young's modulus, for example. The Young's modulus is preferably 2 GPa or more from the viewpoint of optimizing the drive suppression. In addition, since the protective film 82 has insulating properties, the progress of migration between the one end 80b and the first drive wiring 91 and the like can be suppressed or prevented. In addition, when the second drive electrode 80 is disposed below the piezoelectric body 70 as a lower electrode and the first drive electrode 60 is disposed above the piezoelectric body 70 as an upper electrode, the drive electrode end position means a position overlapping with the end of the first drive electrode 60 on the -X direction side. However, the drive electrode end position is not limited to only the end of the first drive electrode 60 on the -X direction side, and may be set using an end located in either direction of the first drive electrode 60 or the second drive electrode 80, or a combination of multiple ends thereof.

[0046] As shown in FIG. 7, a wiring portion 85 is provided on the -X direction side of the one end 80b of the second driving electrode 80 in the -X direction. Note that the wiring portion 85 is omitted from FIG. 4 and FIG. 6. The wiring portion 85 is formed in the same layer as the second driving electrode 80, but is electrically discontinuous with the second driving electrode 80. The wiring portion 85 is formed from the one end 70b of the piezoelectric body 70 in the -X direction to the one end 60b of the first driving electrode 60 in the -X direction, with a gap between the one end 80b of the second driving electrode 80 and the one end 60b of the first driving electrode 60 in the -X direction. The one end 60b of the first driving electrode 60 in the -X direction is drawn out to the outside beyond the one end 70b of the piezoelectric body 70. The wiring portion 85 is provided for each piezoelectric element 300, and a plurality of wiring portions 85 are arranged at predetermined intervals along the Y axis direction. It is preferable that the wiring portion 85 is formed in the same layer as the second driving electrode 80. This simplifies the manufacturing process of the wiring portion 85, thereby reducing costs. However, the wiring portion 85 may be formed in a layer separate from the second drive electrode 80.

[0047] 6 and 7, a first drive wiring 91 is electrically connected to the first drive electrode 60, which is an individual electrode, and an extension portion 92a and an extension portion 92b of a second drive wiring 92 are electrically connected to the second drive electrode 80, which is a common electrode. The first drive wiring 91 and the second drive wiring 92 function as drive wiring for applying a voltage for driving the piezoelectric body 70 from the wiring substrate 120.

[0048] The material of the first drive wiring 91 and the second drive wiring 92 is a material having electrical conductivity, and for example, gold (Au), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), platinum (Pt), aluminum (Al), etc. can be used. In this embodiment, gold (Au) is used as the first drive wiring 91 and the second drive wiring 92. In this embodiment, the first drive wiring 91 and the second drive wiring 92 are formed by sputtering. Note that the first drive wiring 91 and the second drive wiring 92 may be formed by any known film formation technique, not limited to sputtering.

[0049] The first drive wiring 91 and the second drive wiring 92 are formed in the same layer in a state where they are electrically discontinuous from each other. This allows the first drive wiring 91 and the second drive wiring 92 to be formed in a common process, and compared to the case where the first drive wiring 91 and the second drive wiring 92 are formed separately, the manufacturing process can be simplified and a decrease in productivity of the liquid ejection head 510 can be suppressed. However, the first drive wiring 91 and the second drive wiring 92 may be formed in different layers from each other. The first drive wiring 91 and the second drive wiring 92 may have an adhesion layer that improves adhesion with the first drive electrode 60 and the second drive electrode 80 and the vibration plate 50.

[0050] The first drive wiring 91 is provided for each first drive electrode 60. As shown in Fig. 7, the first drive wiring 91 is connected to the vicinity of one end 60b of the first drive electrode 60 via a wiring portion 85, and is drawn out in the -X direction onto the vibration plate 50. The first drive wiring 91 is electrically connected to one end 60b in the -X direction of the first drive electrode 60, which is drawn out to the outside beyond one end 70b of the piezoelectric body 70. The wiring portion 85 may be omitted, and the first drive wiring 91 may be directly connected to one end 60b of the first drive electrode 60.

[0051] As shown in Fig. 4, the second drive wiring 92 extends along the Y-axis direction, is bent at both ends in the Y-axis direction, and is drawn out along the X-axis direction. The second drive wiring 92 has an extension portion 92a and an extension portion 92b that extend along the Y-axis direction. As shown in Figs. 4 and 5, the ends of the first drive wiring 91 and the second drive wiring 92 extend so as to be exposed in the through-hole 32 of the sealing substrate 30, and are electrically connected to the wiring substrate 120 within the through-hole 32.

[0052] The wiring board 120 is formed of, for example, a flexible printed circuit (FPC). A plurality of wirings are formed on the wiring board 120 for connection to the control device 580 and a power supply circuit (not shown). Instead of the FPC, the wiring board 120 may be formed of any flexible board such as a flexible flat cable (FFC). An integrated circuit 121 having a switching element and the like is mounted on the wiring board 120. A command signal for driving the piezoelectric element 300 and the like are input to the integrated circuit 121. The integrated circuit 121 controls the timing of supplying a drive signal for driving the piezoelectric element 300 to the first drive electrode 60 based on the command signal.

[0053] As shown in FIG. 6, the temperature detection unit 410 includes a temperature detection resistor 415 and a temperature detection wiring 93. The temperature detection resistor 415 is a resistive wiring used to detect the temperature of the ink in the pressure chamber 12. The temperature detection wiring 93 electrically connects the wiring board 120 and the temperature detection resistor 415. More specifically, the temperature detection wiring 93 includes a first temperature detection wiring 931 connected to one end of the temperature detection resistor 415 and a second temperature detection wiring 932 connected to the other end of the temperature detection resistor 415. The temperature detection wiring 93 is formed, for example, in the same layer as the first drive wiring 91, the second drive wiring 92, and a humidity detection wiring 94 described later, and is formed so as to be electrically discontinuous with each other. An end of the temperature detection wiring 93 is extended so as to be exposed to the through hole 32 of the sealing substrate 30, and is electrically connected to the wiring board 120 within the through hole 32.

[0054] The material of the temperature detection resistor 415 is a material whose electrical resistance value has temperature dependency, and can be, for example, gold (Au), platinum (Pt), iridium (Ir), aluminum (Al), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), etc. Among these, platinum (Pt) is suitable as the material of the temperature detection resistor 415 from the viewpoints of large change in electrical resistance due to temperature, stability and high accuracy.

[0055] As shown in FIG. 7, the temperature detection resistor 415 is formed in the same layer as the first drive electrode 60 in the stacking direction, for example, and is formed so as to be electrically discontinuous with the first drive electrode 60. In this embodiment, the temperature detection resistor 415 is formed together with the first drive electrode 60 in the process of forming the first drive electrode 60. As a result, the temperature detection resistor 415 is formed of platinum (Pt), which is the same material as the first drive electrode 60, and the thickness of the temperature detection resistor 415 is about 80 nanometers, similar to the first drive electrode 60. However, this is not limited thereto, and the temperature detection resistor 415 may be formed separately from the process of forming the first drive electrode 60, or may be formed together with a conductor wiring different from that of the first drive electrode 60.

[0056] The temperature detection wiring 93 is made of a conductive material, such as gold (Au), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), platinum (Pt), aluminum (Al), etc. The temperature detection wiring 93 is made of gold (Au), the same material as the first drive wiring 91, the second drive wiring 92, and the humidity detection wiring 94 described below. However, the temperature detection wiring 93 may be made of any material other than gold (Au), and may be made of a different material from the first drive wiring 91, the second drive wiring 92, and the humidity detection wiring 94.

[0057] As shown in FIG. 4, in this embodiment, the temperature detection resistor 415 is continuously formed so as to surround the periphery of the first pressure chamber row L1 and the second pressure chamber row L2 in a plan view. More specifically, the temperature detection resistor 415 includes a first extension portion 415A electrically connected to the first temperature detection wiring 931, a third extension portion 415C electrically connected to the second temperature detection wiring 932, and a second extension portion 415B between the first extension portion 415A and the third extension portion 415C. The area surrounded by the first extension portion 415A, the second extension portion 415B, and the third extension portion 415C is also called a "temperature detection area." In the example of FIG. 4, the temperature detection resistor 415 has two temperature detection areas, a first temperature detection area including the first pressure chamber row L1 and a second temperature detection area including the second pressure chamber row L2.

[0058] The first extension portion 415A is disposed on one side of the pressure chambers 12 in the arrangement direction, specifically on the -Y direction side, and extends along the X-axis direction, which is the intersecting direction. The second extension portion 415B is disposed on the outer side of the liquid ejection head 510 than the first pressure chamber row L1 and the second pressure chamber row L2, and extends along the Y-axis direction, which is the arrangement direction. The third extension portion 415C is disposed on the other side of the pressure chambers 12 in the arrangement direction, specifically on the +Y direction side, and extends along the X-axis direction. In this way, the temperature detection resistor 415 is disposed so as to surround the first pressure chamber row L1 and the second pressure chamber row L2. By widening the area in which the temperature detection resistor 415 is disposed, the temperature of the ink in the entire liquid ejection head 510 can be detected.

[0059] As shown in FIG. 6 and FIG. 7, the temperature detection resistor 415 is arranged so as to pass near the ink flow path in the pressure chamber substrate 10. In this embodiment, the second extension portion 415B of the temperature detection resistor 415 is arranged so as to pass over the throttle portion 13 near each pressure chamber 12. Also, as shown in FIG. 4, the second extension portion 415B is formed as a so-called meandering pattern that goes back and forth multiple times along the arrangement direction. By increasing the wiring length of the part of the temperature detection resistor 415 that passes near the pressure chamber 12 and is likely to contribute to ink temperature detection, it is possible to improve the detection accuracy of the ink temperature in the pressure chamber 12. However, the second extension portion 415B may have any shape, and may be formed in a meandering pattern that goes back and forth multiple times along the intersecting direction instead of the arrangement direction, or may be formed in any shape such as a straight line or a wave shape instead of the meandering pattern. Furthermore, the position of the temperature detection resistor 415 is not limited to above the throttling portion 13, but may be any position above the pressure chamber 12, and if it cannot be placed above the pressure chamber 12, it may be a position close to the pressure chamber 12.

[0060] As shown in FIG. 4, the humidity detection units 210 are disposed on the outside of the pressure chamber substrate 10 along the direction perpendicular to the first arrangement direction and the second arrangement direction in a plan view. In other words, the pair of humidity detection units 210 are disposed so as to sandwich the first pressure chamber row L1 and the second pressure chamber row L2. Each humidity detection unit 210 is disposed so that at least a part of the humidity detection unit 210 contacts the sealed space. By providing the humidity detection unit 210 individually for each of the sealed spaces corresponding to the first pressure chamber row L1 and the second pressure chamber row L2, information on the humidity of each pressure chamber row can be obtained with high accuracy. The humidity detection units 210 are disposed at both ends along the direction perpendicular to the first arrangement direction and the second arrangement direction, so that the humidity detection units 210 can be easily disposed so as to contact the sealed spaces, and an increase in the size of the humidity detection unit 510 along the arrangement direction can be suppressed. Furthermore, when humidity control unit 250 or the like is provided as an IC chip on wiring board 120, the layout of conductor wiring on wiring board 120 becomes easier.

[0061] The humidity detection unit 210 includes a humidity detection wiring 94, a first detection electrode 211, a second detection electrode 212, and an intermediate layer 215. In FIG. 4, for convenience of illustration, the humidity detection wiring 94 is not included in the humidity detection unit 210, but the humidity detection unit 210 includes the humidity detection wiring 94. As shown in FIG. 4, the first detection electrode 211 and the second detection electrode 212 are arranged in parallel to each other along the Y direction at a predetermined distance from each other in the X direction so as to be electrically discontinuous. Although detailed illustration of the shapes of the first detection electrode 211 and the second detection electrode 212 is omitted, they may be any shape such as a straight shape, a flat plate shape, or the above-mentioned comb shape.

[0062] The first detection electrode 211 and the second detection electrode 212 can be formed of any conductive material, for example, metals such as platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti), conductive metal oxides such as indium tin oxide abbreviated as ITO, and other conductive materials. The first detection electrode 211 and the second detection electrode 212 may be formed by laminating a plurality of materials such as platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti). The first detection electrode 211 and the second detection electrode 212 may be made of the same material or different materials.

[0063] In this embodiment, the first detection electrode 211 and the second detection electrode 212 are formed using iridium (Ir) the same as the second drive electrode 80. This allows the process of forming the first detection electrode 211 and the second detection electrode 212 to be common to the process of forming the second drive electrode 80, and suppresses a decrease in productivity of the liquid ejection head 510. In addition, for example, gold (Au), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), platinum (Pt), aluminum (Al), etc. can be used for the first detection electrode 211 and the second detection electrode 212, and it is also possible to commonize the material for the first drive wiring 91, the second drive wiring 92, the temperature detection wiring 93, and the humidity detection wiring 94. In addition, as an example of a process order when the process of forming the first detection electrode 211 and the second detection electrode 212 and the process of forming the second drive electrode 80 are common, first, the intermediate layer 215 is formed, and after the first detection electrode 211, the second detection electrode 212, and the second drive electrode 80 are formed in the same process, the protective film 82 is formed at the end positions of the drive electrodes. In addition, the first detection electrode 211 and the second detection electrode 212 may be formed using a material different from that of the second drive electrode 80, and may be formed in a process different from that of the second drive electrode 80.

[0064] Between the first detection electrode 211 and the second detection electrode 212, the intermediate layer 215 is formed. The intermediate layer 215 is formed to be in contact with the first detection electrode 211 and the second detection electrode 212 so that the current from the humidity detection power supply unit 230, which is a constant current circuit, flows to the intermediate layer 215. Note that "current flows through the intermediate layer 215" means that the current flows inside the intermediate layer 215 formed between the first detection electrode 211 and the second detection electrode 212. Note that it may also include the current flowing through the surface of the intermediate layer 215 and the interface between the intermediate layer 215 and another layer. In this embodiment, by detecting the electrical resistance of the current flowing through the protective film 82, it is possible to manage the change over time in the moisture absorption state of the protective film 82 and the change over time in the performance of the protective film 82 caused by humidity. Note that the intermediate layer 215 may be doped with a metal such as chromium (Cr) by ion implantation or the like so that the current for humidity detection can easily flow.

[0065] The intermediate layer 215 is a humidity detection target, and is formed of a material whose electrical resistance changes depending on humidity. The intermediate layer 215 may be a member laminated on at least one of the piezoelectric body 70, the vibration plate 50, and the pressure chamber substrate 10, which may be affected by humidity and may cause performance degradation in the piezoelectric element 300 or in its vicinity, among the members constituting the liquid ejection head 510. The intermediate layer 215 is formed of a material having a higher water absorption rate than the protective film 82. The "water absorption rate" is determined, for example, by exposing a sample of the member to be analyzed to heavy water and quantitatively analyzing the amount of heavy water that has entered the sample by an elemental analysis method such as secondary ion mass spectrometry (SIMS evaluation). In this embodiment, the intermediate layer 215 is formed of an epoxy resin, and the water absorption rate of the intermediate layer 215 is 1.8% or less.

[0066] In a high humidity environment, the protective film 82 may absorb moisture and deteriorate, resulting in a decrease in performance. As shown in FIG. 7, in this embodiment, an adhesive 33, which will be described later, is present between the protective film 82 and the sealed space, and the protective film 82 is not in direct contact with the sealed space. However, moisture present in the sealed space may be absorbed by the adhesive 33, and the protective film 82 may be in contact with the adhesive 33 that has absorbed the moisture, so that the protective film 82 may absorb the moisture present in the sealed space via the adhesive 33. In addition, the performance of the piezoelectric element 300 may be deteriorated due to the moisture absorbed by the protective film 82 adhering thereto. By using a material having a higher water absorption rate than the protective film 82 as the intermediate layer 215, moisture is preferentially absorbed by the intermediate layer 215 rather than the protective film 82. This makes it possible to suppress a decrease in the performance of the protective film 82 and the piezoelectric element 300 due to moisture being absorbed by the protective film 82.

[0067] As shown in FIG. 7, a part of the second detection electrode 212, the first detection electrode 211, and the intermediate layer 215 are formed on the piezoelectric body 70 via the intermediate layer 84. In this embodiment, the intermediate layer 84 is formed in the same layer as the second drive electrode 80, and is spaced apart from the other end 80a, which is the end of the second drive electrode 80 in the +X direction, so as to be electrically discontinuous with the second drive electrode 80. Although not shown in FIG. 7, a protective film made of the same material as the protective film 82 may be provided between the second drive electrode 80 and the intermediate layer 84. The intermediate layer 84 is made of the same material as the second drive electrode 80 and has the same thickness as the second drive electrode 80. By forming at least a part of the second detection electrode 212, the first detection electrode 211, and the intermediate layer 215 on the piezoelectric body 70 via such an intermediate layer 84, it is possible to suppress a decrease in adhesion between the second detection electrode 212, the first detection electrode 211, and the intermediate layer 215 and the piezoelectric body 70, compared to a configuration in which they are formed directly on the piezoelectric body 70. Note that the second detection electrode 212, the first detection electrode 211, and the intermediate layer 215 may be formed on the piezoelectric body 70 or on the diaphragm 50.

[0068] In this embodiment, the humidity detection unit 210 is provided such that the piezoelectric body 70 is located between the humidity detection unit 210 and the temperature detection resistor 415 in the stacking direction. As a result, the humidity detection unit 210 and the temperature detection resistor 415 are separated from each other by the piezoelectric body 70, and therefore electrical conduction between the humidity detection unit 210 and the temperature detection resistor 415 can be suppressed. This makes it possible to suppress problems occurring in the detection of humidity and temperature.

[0069] As shown in Fig. 4, in this embodiment, the first driving electrode 60, the temperature detection resistor 415, and the second detection electrode 212 are provided in this order from the inside to the outside of the liquid ejection head 510 along the X direction in a plan view of the liquid ejection head 510 in the stacking direction. Also, as shown in Fig. 7, the first detection electrode 211 and the intermediate layer 215 of the humidity detection unit 210 are provided at positions overlapping the temperature detection resistor 415 in the stacking direction. Note that "provided at an overlapping position" means that the first detection electrode 211 and the intermediate layer 215 are provided at positions that appear to overlap the temperature detection resistor 415 in a plan view of the liquid ejection head 510 in the stacking direction. Therefore, compared to a configuration in which the first detection electrode 211 and the intervening layer 215 are located in the +X direction from the temperature detection resistor 415 and neither the first detection electrode 211 nor the intervening layer 215 overlaps with the temperature detection resistor 415, it is possible to suppress an increase in the size of the liquid ejection head 510 along the X direction. Also, compared to a configuration in which neither the first detection electrode 211 nor the intervening layer 215 overlaps with the temperature detection resistor 415, the first detection electrode 211, the intervening layer 215, and the temperature detection resistor 415 can be arranged to be closer to each other, so that the difference between the humidity detection position and the temperature detection position can be suppressed, and when temperature is used to calculate humidity, humidity can be calculated more accurately. Also, since humidity can be calculated more accurately, when a judgment using humidity is executed in the control of the ejection operation in the head control unit 520, the ejection operation can be controlled more appropriately.

[0070] The sealing substrate 30 is bonded at the lower end of one wall portion 30W to the upper end portions of the first driving wiring 91, the protective film 82, and the second driving wiring 92 with the adhesive 33. The sealing substrate 30 is bonded at the lower end surface of the other wall portion 30W to the upper end surfaces of the intermediate layer 215 and the second detection electrode 212 with the adhesive 33. More specifically, the sealing substrate 30 is bonded to the first driving wiring 91, the protective film 82, and the second driving wiring 92, and to the intermediate layer 215 and the second detection electrode 212 with the adhesive 33 so as to form the above-mentioned sealed space. In the above description, the "upper end surface" means the end surface in the -Z direction, and the "lower end surface" means the end surface in the +Z direction.

[0071] In this embodiment, the water absorption rate of the adhesive 33 is higher than that of the protective film 82 and the intervening layer 215. Therefore, moisture is absorbed preferentially into the adhesive 33 rather than the protective film 82, and the deterioration of the performance of the protective film 82 can be suppressed. In addition, moisture is absorbed preferentially into the adhesive 33 rather than the intervening layer 215, so that the intervening layer 215 can be prevented from being excessively absorbed by the moisture and thus deteriorating, and the life of the humidity detection unit 210 can be suppressed. Furthermore, since the adhesive 33 is in contact with the intervening layer 215, the moisture absorbed into the intervening layer 215 moves to the adhesive 33, which has a higher water absorption rate than the intervening layer 215. Therefore, the intervening layer 215 can be prevented from being absorbed by the moisture and thus deteriorating, and the life of the humidity detection unit 210 can be suppressed.

[0072] The first drive wiring 91, the protective film 82, the second drive wiring 92, the first detection electrode 211, the intermediate layer 215, and the second detection electrode 212 are formed so that the heights of the upper end faces of the respective components are the same with respect to the upper end face of the piezoelectric body 70. This allows the heights of the respective components in the stacking direction to be the same, and allows the respective components to be bonded to the sealing substrate 30 with high precision.

[0073] In this embodiment, the adhesive 33 is in contact with a portion of the upper end surface of the intervening layer 215, and the intervening layer 215 has an exposed portion EX exposed to the sealed space. Since the intervening layer 215 is in contact with the sealed space in the holding part 31, the electrical resistance value of the intervening layer 215 is likely to change due to a humidity change in the sealed space. Therefore, the humidity control part 250 can detect the humidity change in the sealed space with high accuracy. Note that the adhesive 33 may be in contact with the entire upper end surface of the intervening layer 215, and the intervening layer 215 may not have an exposed portion EX.

[0074] The second detection electrode 212 is formed so as to cover the other end 70a, which is an end different from the one end 70b of the piezoelectric body 70. By forming the second detection electrode 212 in this manner, it is possible to prevent the piezoelectric body 70 from absorbing moisture and deteriorating in performance due to the other end 70a being exposed to the atmosphere outside the sealing substrate 30. Note that the second detection electrode 212 may be formed only on the intermediate layer 84 and may not be formed so as to cover the other end 70a.

[0075] The sealing substrate 30 has an air opening portion 34 in the ceiling portion 30T. Gas generated when the adhesive 33 hardens is discharged through the air opening portion 34, and the like, and thus the occurrence of a pressure difference between the inside of the sealed space and the outside of the sealing substrate 30 can be suppressed. In this embodiment, the air opening portion 34 is formed at a position corresponding to a corner of the sealed space in the ceiling portion 30T, more specifically, at a position corresponding to an end in the -Y direction and an end in the +X direction of the sealed space corresponding to the first pressure chamber row L1. Although not shown, in the sealing substrate 30 corresponding to the second pressure chamber row L2, the air opening portion 34 is formed at a position corresponding to an end in the -Y direction and an end in the -X direction of the sealed space corresponding to the second pressure chamber row L2. That is, the air opening portion 34 is formed at a position corresponding to an end in the -Y direction and an outer end in the X direction in each sealed space. By forming the air opening portion 34 at such a position, it is possible to suppress the attachment of dust and the like entering from the outside of the sealing substrate 30 through the air opening portion 34 to the piezoelectric element 300. The atmosphere opening portion 34 may be formed at a position corresponding to the end in the +Y direction.

[0076] Furthermore, since the atmosphere open portion 34 is located at a position in the ceiling portion 30T corresponding to the end in the +X direction of the sealed space corresponding to the first pressure chamber row L1, the distance between the atmosphere open portion 34 and the protective film 82 is greater than the distance between the atmosphere open portion 34 and the intervening layer 215. Therefore, moisture that penetrates from the outside of the sealing substrate 30 through the atmosphere open portion 34 can be absorbed by the intervening layer 215 before the protective film 82 absorbs it, thereby suppressing the protective film 82 from absorbing moisture through the adhesive 33 and suppressing a decrease in performance of the protective film 82. Note that the sealing substrate 30 does not necessarily have to have the atmosphere open portion 34.

[0077] 4, the humidity detection wiring 94 includes a first humidity detection wiring 941 that electrically connects the wiring substrate 120 and the first detection electrode 211, and a second humidity detection wiring 942 that electrically connects the wiring substrate 120 and the second detection electrode 212. Ends of the first humidity detection wiring 941 and the second humidity detection wiring 942 are extended so as to be exposed in the through hole 32 of the sealing substrate 30, and are electrically connected to the wiring substrate 120 within the through hole 32.

[0078] The humidity detection wiring 94 is made of a conductive material, such as gold (Au), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), platinum (Pt), aluminum (Al), etc. The humidity detection wiring 94 is made of gold (Au), the same material as the first drive wiring 91, the second drive wiring 92, and the temperature detection wiring 93. However, the humidity detection wiring 94 may be made of any material other than gold (Au), and may be made of a different material from the first drive wiring 91, the second drive wiring 92, and the temperature detection wiring 93.

[0079] 4, the first drive wiring 91, the second drive wiring 92, the temperature detection wiring 93, and the humidity detection wiring 94 are connected to the wiring substrate 120 in this order from the center CP of the liquid ejection head 510 toward the outside. "The outside of the liquid ejection head 510" means a position closer to the peripheral edge of the pressure chamber substrate 10 than a predetermined reference position in the direction away from the center CP. The liquid ejection head 510 of this embodiment is configured to have the following characteristics by arranging the conductor wiring connected to the wiring substrate 120 in this order.

[0080] The first temperature detection wiring 931 and the second temperature detection wiring 932 are arranged outside the liquid ejection head 510 relative to the first drive wiring 91 and the second drive wiring 92, and the first humidity detection wiring 941 and the second humidity detection wiring 942 are arranged outside the liquid ejection head 510 relative to the first temperature detection wiring 931 and the second temperature detection wiring 932.

[0081] By arranging the temperature detection wiring 93 between the first drive wiring 91 and the second drive wiring 92 and the humidity detection wiring 94, the first humidity detection wiring 941 and the second humidity detection wiring 942 can be arranged at a position away from the first drive wiring 91 and the second drive wiring 92. Therefore, compared with an embodiment in which the first humidity detection wiring 941 and the second humidity detection wiring 942 are arranged at a position adjacent to the first drive wiring 91 and the second drive wiring 92, it is possible to suppress or prevent the influence of noise of the drive voltage on the detection of humidity. In addition, by arranging the first temperature detection wiring 931 and the second temperature detection wiring 932 at a position closer to the drive wiring than the first humidity detection wiring 941 and the second humidity detection wiring 942, it is possible to shorten the wiring length of the temperature detection resistor 415 and the temperature detection wiring 93, and it is possible to detect the temperature efficiently.

[0082] According to the liquid ejection head 510 of the embodiment described above, since the water absorption rate of the protective film 82 is lower than that of the intervening layer 215, it is possible to cause the intervening layer 215 to absorb moisture preferentially rather than the protective film 82, and it is possible to prevent the performance of the protective film 82 and the piezoelectric element 300 from being deteriorated due to the absorption of moisture by the protective film 82. Therefore, it is possible to appropriately obtain information regarding the humidity in the piezoelectric element 300 and members in the vicinity thereof, and appropriately manage the effects of humidity.

[0083] Furthermore, since the water absorption rate of the protective film 82 is lower than that of the adhesive 33, the adhesive 33 can absorb water preferentially over the protective film 82, and deterioration of the performance of the protective film 82 can be suppressed.

[0084] Furthermore, since the water absorption rate of the intervening layer 215 is lower than that of the adhesive 33, the adhesive 33 can absorb moisture preferentially over the intervening layer 215, and the shortening of the life span of the humidity detection unit 210 can be suppressed.

[0085] In addition, because intervening layer 215 is in contact with adhesive 33, moisture absorbed in intervening layer 215 can be transferred to adhesive 33. This makes it possible to suppress the amount of moisture absorbed in intervening layer 215, and thus suppress a decrease in the life span of humidity detection unit 210.

[0086] Furthermore, since the intervening layer 215 has the exposed portion EX, it can be in direct contact with the sealed space, and the humidity control unit 250 can detect the humidity change in the sealed space with higher accuracy.

[0087] Furthermore, since protective film 82 has a lower water absorption rate than intermediate layer 215, which has a water absorption rate of 1.8% or less, deterioration in the performance of protective film 82 and piezoelectric element 300 caused by moisture absorption by protective film 82 can be further suppressed.

[0088] Furthermore, since the distance between the atmospheric opening portion 34 and the protective film 82 is greater than the distance between the atmospheric opening portion 34 and the intervening layer 215, moisture that penetrates from outside the sealing substrate 30 through the atmospheric opening portion 34 can be absorbed by the intervening layer 215 before it is absorbed by the protective film 82, thereby suppressing the absorption of moisture by the protective film 82 and further suppressing the deterioration of the performance of the protective film 82.

[0089] Furthermore, since the first detection electrode 211 and the second detection electrode 212 are formed from the same material as the second drive electrode 80, the formation process of the first detection electrode 211 and the second detection electrode 212 can be common to the formation process of the second drive electrode 80, thereby suppressing a decrease in productivity of the liquid ejection head 510.

[0090] Furthermore, since the second driving electrode 80 and the second detection electrode 212 are provided at the same height in the stacking direction, the second driving electrode 80 and the second detection electrode 212 can be adhered to the sealing substrate 30 with high precision.

[0091] B. Other embodiments: (B1) In the above embodiment, the liquid ejection head 510 includes the humidity detection unit 210 configured as a resistance detection type humidity sensor, but the present disclosure is not limited thereto. The liquid ejection head 510 may include a humidity detection unit configured as a capacitance type humidity sensor instead of the humidity detection unit 210. In this embodiment, humidity is detected by utilizing the property that the dielectric constant of the intervening layer 215 changes due to moisture absorption, causing a change in capacitance. The intervening layer 215 may be formed using the same material as in the first embodiment. In addition, the intervening layer 215 may be formed using a material suitable for a humidity-sensitive film, such as a polymer material such as a cellulose compound, a polyvinyl compound, or an aromatic polymer, or a metal oxide such as aluminum oxide (Al2O3) or silicon oxide (SiO2).

[0092] In this embodiment, the liquid ejection head 510 includes a capacitance measurement unit instead of the humidity detection resistance measurement unit 240. The humidity detection power supply unit 230 applies a predetermined voltage to the humidity detection unit 210 under the control of the humidity management unit 250. The capacitance measurement unit detects the capacitance of the humidity detection unit 210, for example, by measuring the time it takes for the voltage value applied to the humidity detection unit 210 by the humidity detection power supply unit 230 to reach a predetermined reference voltage. The detection result by the capacitance measurement unit is output to the humidity management unit 250.

[0093] The humidity management unit 250 derives information on the humidity of the object to be detected using the capacitance of the humidity detection unit 210 acquired from the capacitance measurement unit and a humidity calculation formula stored in advance in the storage unit 584. The humidity calculation formula indicates the correspondence between the capacitance of the object to be detected and the humidity. Instead of the humidity calculation formula, a conversion table indicating the correspondence between the capacitance of the object to be detected and the humidity may be used. Furthermore, the storage unit 584 may store the correspondence between the capacitance of the object to be detected and the change over time in the performance of the object to be detected. The capacitance may be measured using various general methods such as a constant current discharge method. This form also provides the same effects as the above embodiment.

[0094] (B2) In the above embodiment, the water absorption rate of the adhesive 33 is higher than that of the intervening layer 215, but the present disclosure is not limited thereto. The water absorption rate of the adhesive 33 may be the same as that of the intervening layer 215. In such an embodiment, the intervening layer 215 may be formed using the same material as the adhesive 33. According to such an embodiment, the process of forming the intervening layer 215 and the process of bonding the sealing substrate 30 can be shared, and a decrease in productivity of the liquid ejection head 510 can be suppressed.

[0095] (B3) In the above embodiment, the entire protective film 82 is formed from the same material, but the present disclosure is not limited to this. Of the protective film 82, the portion in contact with the second drive electrode 80 and the piezoelectric body 70 may be formed from a material having a lower water absorption rate than the other portions, and the other portions may be formed from the same material as the adhesive 33. This form also provides the same effects as the above embodiment. In addition, even if the cost of a material with a higher water absorption rate is higher, an increase in the manufacturing cost of the liquid ejection head 510 can be suppressed.

[0096] (B4) In the above embodiment, the adhesive 33 is in contact with a portion of the upper end surface of the intervening layer 215, but the present disclosure is not limited to this. The adhesive 33 may be in contact only with the upper end surface of the second detection electrode 212, and may not be in contact with the upper end surface of the intervening layer 215. According to this embodiment, the intervening layer 215 can be in contact with the sealed space over the entire upper end surface, and the humidity control unit 250 can detect humidity changes in the sealed space with greater accuracy.

[0097] (B5) In the above embodiment, the humidity detection unit 210 is formed by stacking the first detection electrode 211, the intervening layer 215, and the second detection electrode 212 in the X direction, but the present disclosure is not limited to this. The humidity detection unit 210 may be formed by stacking the first detection electrode 211, the intervening layer 215, and the second detection electrode 212 in the Z direction. This form also provides the same effects as the above embodiment.

[0098] FIG. 8 is a cross-sectional view showing the configuration of a liquid ejection head 510b of another embodiment. As shown in FIG. 8, the sealing substrate 30 of this embodiment has a conductive layer 35 on the lower end surface of the wall portion 30W on the side to be bonded to the humidity detection portion 210. The conductive layer 35 is formed along the Y-axis direction. In addition, the conductive layer 35 has a resin portion (not shown) formed of synthetic resin to have a convex shape in the +Z direction and having elasticity at the end in the Y-axis direction, and a conductive portion (not shown) that covers the surface of the resin portion and has conductivity. The conductive portion is connected to the second humidity detection wiring 942 at the end in the +Y direction (not shown). In other words, the conductive layer 35 has a resin core bump structure at the end in the Y-axis direction. In this embodiment, the sealing substrate 30 is bonded to the first detection electrode 211 by the intermediate layer 215 functioning as an adhesive, and forms a sealed space sealed from the space outside the holding portion 31.

[0099] When the sealing substrate 30 is attached to the humidity detection unit 210, the conductive layer 35 contacts the upper end surface of the intermediate layer 215. At this time, the intermediate layer 215 is sandwiched between the conductive layer 35 connected to the second humidity detection wiring 942 and the first detection electrode 211 connected to the first humidity detection wiring 941, and a current flows from the humidity detection power supply unit 230, which is a constant current circuit. That is, in this embodiment, the conductive layer 35 corresponds to the second detection electrode 212 in the above embodiment. According to this embodiment, the same effect as the above embodiment is achieved. In addition, since the conductive layer 35 can also serve as the second detection electrode 212, which is a part of the components of the humidity detection unit 210, the configuration of the humidity detection unit 210 can be simplified and the liquid ejection head 510b can be prevented from becoming large. Furthermore, since the process of forming the conductive layer 35 on the sealing substrate 30 can be performed in parallel with the process of forming the intervening layer 215 on the first detection electrode 211, a decrease in productivity of the liquid ejection head 510b can be suppressed compared to a configuration in which the second detection electrode 212 is formed separately after the formation of the intervening layer 215.

[0100] As a modification of this embodiment, the conductive layer 35 may be provided on the side of the sealing substrate 30 on which the protective film 82 is provided. In this case, when the sealing substrate 30 is attached to the extension portion 92b of the second driving electrode 80, the conductive layer 35 is located on the upper surface of the extension portion 92b via the adhesive 33. That is, the adhesive 33 is sandwiched between the conductive layer 35 and the extension portion 92b of the second driving electrode 80. The conductive layer 35 has a resin core bump structure at the end in the Y-axis direction and is connected to the second humidity detection wiring 942. In this configuration, the adhesive 33 corresponds to the intermediate layer 215 in the above embodiment, and the second driving electrode 80 corresponds to the first detection electrode 211 in the above embodiment. By passing a current through the adhesive 33 sandwiched between the conductive layer 35 and the extension portion 92b of the second driving electrode 80 and detecting the electrical resistance of the current flowing through the adhesive 33, information on the humidity of at least one of the sealed space and the protective film 82 is derived. According to this configuration, the second driving electrode 80 can also function as the first detection electrode 211, which is one of the components of the humidity detection unit 210, so that the configuration of the humidity detection unit 210 can be simplified and the liquid ejection head 510b can be prevented from becoming large.

[0101] (B6) In the above embodiment, the atmosphere opening portion 34 is formed in the ceiling portion 30T at a position corresponding to the end in the -Y direction and the end in the +X direction of the sealed space corresponding to the first pressure chamber row L1, but the present disclosure is not limited thereto. The atmosphere opening portion 34 may be formed in the ceiling portion 30T at a position corresponding to the center in the -Y direction and the end in the +X direction of the sealed space corresponding to the first pressure chamber row L1. Even in this embodiment, the atmosphere opening portion 34 is located in the ceiling portion 30T at a position corresponding to the end in the +X direction of the sealed space corresponding to the first pressure chamber row L1, so that the distance between the atmosphere opening portion 34 and the protective film 82 can be made larger than the distance between the atmosphere opening portion 34 and the intermediate layer 215. Therefore, moisture that penetrates from the outside of the sealing substrate 30 through the atmosphere opening portion 34 can be absorbed by the intermediate layer 215 before the protective film 82, which suppresses the absorption of moisture by the protective film 82 and suppresses the performance of the protective film 82 from deteriorating.

[0102] (B7) In the above embodiment, the liquid ejection head 510 includes the temperature detection mechanism 400 and the temperature management unit 450, but the present disclosure is not limited thereto. The liquid ejection head 510 does not need to include the temperature detection mechanism 400 and the temperature management unit 450. Even in this embodiment, information related to the humidity of the drive element can be detected by a simple structure in which the drive element and the humidity detection unit 210 are connected to a single wiring board 120. In addition, since the number of components of the liquid ejection head 510 can be reduced, an increase in the manufacturing cost of the liquid ejection head 510 can be suppressed.

[0103] (B8) In the above embodiment, the first detection electrode 211 and the intermediate layer 215 are provided at positions where they overlap the temperature detection resistor 415 in the stacking direction, but the present disclosure is not limited thereto. For example, the first detection electrode 211, the intermediate layer 215, and the second detection electrode 212 may be provided at positions where they overlap the temperature detection resistor 415, or only one of the first detection electrode 211, the intermediate layer 215, and the second detection electrode 212 may be provided at a position where they overlap the temperature detection resistor 415. In addition, the intermediate layer 215 and the second detection electrode 212, or the first detection electrode 211 and the second detection electrode 212 may be provided at a position where they overlap the temperature detection resistor 415 in the stacking direction. That is, at least one of the first detection electrode 211, the intermediate layer 215, and the second detection electrode 212 and the temperature detection resistor 415 may be provided at a position where they overlap each other. According to this embodiment, it is possible to suppress an increase in the size of the liquid ejection head 510 along the X direction, compared to a configuration in which none of the first detection electrode 211, the intervening layer 215, and the second detection electrode 212 overlaps with the temperature detection resistor 415. The first detection electrode 211, the intervening layer 215, and the second detection electrode 212, and the temperature detection resistor 415 may be provided at positions where they do not overlap with each other. According to this embodiment, it is possible to suppress a decrease in the degree of freedom in arranging the first detection electrode 211, the intervening layer 215, the second detection electrode 212, and the temperature detection resistor 415.

[0104] (B9) In the above embodiment, the first driving electrode 60, the temperature detection resistor 415, and the second detection electrode 212 are provided in this order from the inside to the outside of the liquid ejection head 510 along the X direction in a plan view of the liquid ejection head 510 seen along the stacking direction, but the present disclosure is not limited to this. The first driving electrode 60, the temperature detection resistor 415, and the second detection electrode 212 may be provided in this order from the inside to the outside of the liquid ejection head 510 along the Y direction in a plan view of the liquid ejection head 510 seen along the stacking direction. According to this embodiment, it is possible to suppress an increase in the size of the liquid ejection head 510 in the Y direction.

[0105] (B10) In the above embodiment, as shown in Fig. 4, the first drive wiring 91, the second drive wiring 92, the temperature detection wiring 93, and the humidity detection wiring 94 are perpendicular to the wiring substrate 120, but the present disclosure is not limited to this. The first drive wiring 91, the second drive wiring 92, the temperature detection wiring 93, and the humidity detection wiring 94 may cross at an angle with respect to the wiring substrate 120. According to this embodiment, it is possible to suppress positional deviation in the X direction due to thermal expansion caused by temperature change of the first drive wiring 91, the second drive wiring 92, the temperature detection wiring 93, and the humidity detection wiring 94, and to suppress wiring problems caused by wiring pattern deviation.

[0106] (B11) In the above embodiment, the first drive wiring 91 and the second drive wiring 92 are formed by sputtering, but the present disclosure is not limited thereto. The first drive wiring 91 and the second drive wiring 92 may be formed by plating. By forming the first drive wiring 91 and the second drive wiring 92 by plating, an increase in the electrical resistance of the first drive wiring 91 and the second drive wiring 92 can be suppressed compared to a configuration in which the first drive wiring 91 and the second drive wiring 92 are formed by sputtering. In addition, when the first drive wiring 91 and the second drive wiring 92 are formed by either sputtering or plating, an increase in the electrical resistance of the first drive wiring 91 and the second drive wiring 92 can also be suppressed by forming the first drive wiring 91 and the second drive wiring 92 thicker in the stacking direction. By suppressing the increase in electrical resistance of the first drive wiring 91 and the second drive wiring 92 as described above, even if the area of ​​the second drive electrode 80 in a planar view of the liquid ejection head 510 along the stacking direction is reduced as the liquid ejection head 510 is made smaller, and the electrical resistance of the second drive electrode 80 increases, the increase in electrical resistance in the first drive wiring 91, the second drive wiring 92 and the entire second drive electrode 80 can be suppressed.

[0107] (B12) In each of the above embodiments, an example was shown in which a piezoelectric element 300 was used as the drive element. However, a heat generating element including a heater may be used as the drive element. In this case, a heater is provided in each pressure chamber, and ink is ejected from the nozzle by changing the pressure in the pressure chamber using bubbles that are generated when the heater is heated. Even with this form of liquid ejection head, it is possible to obtain the same effects as in each of the above embodiments.

[0108] (B13) In the above embodiment, the intermediate layer 215 is formed of an epoxy resin, and the protective film 82 is formed of a polyimide, but the present disclosure is not limited to this. The intermediate layer 215 may be formed of, for example, a polyimide having a higher water absorption rate than the polyimide used in the protective film 82.

[0109] C. Other forms: The present disclosure is not limited to the above-mentioned embodiment, and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features in the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention column can be appropriately replaced or combined to solve some or all of the above-mentioned problems or to achieve some or all of the above-mentioned effects. Furthermore, if the technical feature is not described as essential in this specification, it can be appropriately deleted.

[0110] (1) According to one embodiment of the present disclosure, a liquid ejection head is provided. The liquid ejection head includes a piezoelectric element in which a first driving electrode, a piezoelectric body, and a second driving electrode are stacked in a stacking direction, a sealing substrate forming a sealed space in which the piezoelectric element is provided, a protective film formed on the piezoelectric body in the stacking direction, and a humidity detection unit formed on the piezoelectric body in the stacking direction, the humidity detection unit having a first detection electrode, an intervening layer, and a second detection electrode, the moisture absorption rate of the protective film being lower than that of the intervening layer. According to the liquid ejection head of this embodiment, since the moisture absorption rate of the protective film is lower than that of the intervening layer, the intervening layer can absorb moisture preferentially over the protective film, and the performance of the protective film and the piezoelectric element can be prevented from being deteriorated due to moisture absorption by the protective film. Therefore, information about the humidity in the piezoelectric element and its neighboring members can be appropriately acquired, and the influence of humidity can be appropriately managed.

[0111] (2) In the liquid ejection head of the above aspect, the sealing substrate may be bonded to the piezoelectric element and the humidity detection unit via an adhesive, and the water absorption rate of the protective film may be lower than that of the adhesive. According to this aspect of the liquid ejection head, since the water absorption rate of the protective film is lower than that of the adhesive, the adhesive can absorb moisture preferentially over the protective film, and deterioration of the performance of the protective film can be further suppressed.

[0112] (3) In the liquid ejection head of the above embodiment, the intervening layer may have a lower water absorption rate than the adhesive. In this liquid ejection head, the intervening layer has a lower water absorption rate than the adhesive, so that the adhesive can absorb moisture preferentially rather than the intervening layer, thereby suppressing a decrease in the life of the humidity detection unit.

[0113] (4) In the liquid ejection head of the above embodiment, the intervening layer may be in contact with the adhesive. According to the liquid ejection head of this embodiment, since the intervening layer is in contact with the adhesive, the moisture absorbed in the intervening layer can be transferred to the adhesive. Therefore, the amount of moisture absorbed in the intervening layer can be suppressed, and the reduction in the life of the humidity detection unit can be suppressed.

[0114] (5) In the liquid ejection head of the above aspect, the intervening layer may have an exposed portion that is exposed to the sealed space. According to the liquid ejection head of this aspect, the intervening layer has an exposed portion and can be in direct contact with the sealed space, so that a humidity change in the sealed space can be detected with higher accuracy.

[0115] (6) In the liquid ejection head of the above aspect, the sealing substrate may be bonded to the piezoelectric element and the humidity detection unit via an adhesive, and the adhesive may be made of the same material as that of the intermediate layer. According to this aspect of the liquid ejection head, since the adhesive is made of the same material as that of the intermediate layer, the step of forming the intermediate layer and the step of bonding the sealing substrate can be performed in the same process, thereby improving the productivity of the liquid ejection head.

[0116] (7) In the liquid ejection head of the above aspect, the intermediate layer may have a water absorption rate of 1.8% or less. This liquid ejection head includes a protective film having a lower water absorption rate than the intermediate layer, which has a water absorption rate of 1.8% or less. This makes it possible to further prevent the performance of the protective film and the piezoelectric element from being deteriorated due to moisture absorption by the protective film.

[0117] (8) In the liquid ejection head of the above aspect, the sealing substrate may have an atmosphere opening portion that opens the sealed space to the atmosphere, and the distance between the atmosphere opening portion and the protective film may be greater than the distance between the atmosphere opening portion and the intermediate layer. According to the liquid ejection head of this aspect, since the distance between the atmosphere opening portion and the protective film is greater than the distance between the atmosphere opening portion and the intermediate layer, moisture that penetrates from outside the sealing substrate through the atmosphere opening portion can be absorbed by the intermediate layer before the protective film absorbs it, thereby suppressing the absorption of moisture by the protective film and further suppressing deterioration of the performance of the protective film.

[0118] (9) In the liquid ejection head of the above aspect, the first detection electrode and the second detection electrode may be formed of the same material as the second drive electrode. According to this aspect of the liquid ejection head, the first detection electrode and the second detection electrode are formed of the same material as the second drive electrode, so that the process of forming the first detection electrode and the second detection electrode can be shared with the process of forming the second drive electrode, thereby improving the productivity of the liquid ejection head.

[0119] (10) In the liquid ejection head of the above embodiment, the second driving electrode and the second detection electrode may be provided at the same height in the stacking direction, and one end of the sealing substrate in a direction intersecting the stacking direction may be provided on the second detection electrode, and the other end of the sealing substrate may be provided on the second driving electrode. According to this form of liquid ejection head, the second driving electrode and the second detection electrode are provided at the same height in the stacking direction, so that the second driving electrode and the second detection electrode can be bonded to the sealing substrate with high precision.

[0120] (11) In the liquid ejection head of the above embodiment, the humidity detection unit may be formed in the stacking direction in the order of the first detection electrode, the intermediate layer, and the second detection electrode, and the second detection electrode may be formed by a conductive layer formed on the sealing substrate. According to this embodiment of the liquid ejection head, the conductive layer can also serve as the second detection electrode, which is one of the components of the humidity detection unit, so that the configuration of the humidity detection unit can be simplified and the liquid ejection head can be prevented from becoming large. In addition, the process of forming the conductive layer on the sealing substrate can be performed in parallel with the process of forming the intermediate layer on the first detection electrode, and the productivity of the liquid ejection head can be improved compared to a configuration in which the second detection electrode is formed separately after the formation of the intermediate layer.

[0121] (12) According to another aspect of the present disclosure, there is provided a liquid ejection system. The liquid ejection system includes the liquid ejection head according to the above embodiment, and a control unit that calculates humidity using a detection result from the humidity detection unit. According to the liquid ejection system of this aspect, moisture is absorbed preferentially by the intervening layer rather than the protective film, and therefore it is possible to prevent the performance of the protective film and the piezoelectric element from being deteriorated due to moisture absorption by the protective film.

[0122] The present disclosure may be realized in various forms other than a liquid ejection apparatus or a liquid ejection head, for example, a method for manufacturing a liquid ejection head, a method for manufacturing a liquid ejection apparatus, etc.

[0123] The present disclosure is not limited to the inkjet type, but can also be applied to any liquid ejection device that ejects liquid other than ink and the liquid ejection head used in such liquid ejection device. For example, the present disclosure can be applied to various liquid ejection devices and their liquid ejection heads as follows: (1) Image recording devices such as facsimile machines. (2) A color material ejection device used in the manufacture of color filters for image display devices such as liquid crystal displays. (3) Electrode material ejection equipment used to form electrodes for organic EL (Electro Luminescence) displays, field emission displays (FEDs), etc. (4) A liquid ejection device that ejects liquid containing a bioorganic substance used in biochip production. (5) A sample ejection device as a precision pipette. (6) Lubricating oil discharge device. (7) A resin liquid ejection device. (8) A liquid ejection device that ejects lubricating oil with pinpoint precision into precision machinery such as watches and cameras. (9) A liquid ejection device that ejects transparent resin liquid, such as ultraviolet curing resin liquid, onto a substrate to form minute hemispherical lenses (optical lenses) used in optical communication elements, etc. (10) A liquid ejection device that ejects an acidic or alkaline etching liquid for etching a substrate or the like. (11) A liquid ejection device having a liquid consuming head that ejects any other minute amount of liquid droplets.

[0124] A "liquid" may be any material that can be consumed by a liquid ejection device. For example, a "liquid" may be any material in a liquid phase, and includes materials in a liquid state with high or low viscosity, as well as materials in a liquid state such as sol, gel water, other inorganic solvents, organic solvents, solutions, liquid resins, and liquid metals (metal melts). In addition to liquids as one state of matter, particles of functional materials made of solids such as pigments and metal particles dissolved, dispersed, or mixed in a solvent are also included in the term "liquid." Representative examples of liquids include the following: (1) The base adhesive and hardener. (2) Paint base paints and thinners, and clear paints and thinners. (3) A main solvent and a dilution solvent containing cells for the cell-based ink. (4) Metallic leaf pigment dispersion and dilution solvent for ink (metallic ink) that exhibits a metallic luster. (5) Gasoline, diesel and biofuels for vehicles. (6) The active pharmaceutical ingredient and protective ingredients of a drug. (7) Phosphors and encapsulants for light-emitting diodes (LEDs). [Explanation of symbols]

[0125] Reference Signs List 10...pressure chamber substrate, 12...pressure chamber, 13...throttling portion, 14...pressure chamber supply path, 15...communication plate, 16...nozzle communication path, 17...first manifold portion, 18...second manifold portion, 19...supply communication path, 20...nozzle plate, 21...nozzle, 30...sealing substrate, 30T...ceiling portion, 30W...wall portion, 31...holding portion, 32...through hole, 33...adhesive, 34...atmospheric opening portion, 35...conductive layer, 40...case member, 41...accommodating portion, 42...third manifold portion, 43...connection port, 44...supply port, 45...compliance substrate, 46...sealing film, 47...fixing Substrate, 48...opening, 49...compliance portion, 50...diaphragm, 55...elastic membrane, 56...insulating membrane, 60...first driving electrode, 60b...one end portion, 70...piezoelectric body, 70a...other end portion, 70b...one end portion, 80...second driving electrode, 80a...other end portion, 80b...one end portion, 82...protective film, 84...intermediate layer, 85...wiring portion, 91...first driving wiring, 92...second driving wiring, 92a...extension portion, 92b...extension portion, 93...temperature detection wiring, 94...humidity detection wiring, 100...manifold, 120...wiring substrate, 121...integrated circuit, 200...humidity detection mechanism, 210... Humidity detection section, 211...first detection electrode, 212...second detection electrode, 215...intervening layer, 230...power supply section for humidity detection, 240...resistance measurement section for humidity detection, 250...humidity control section, 300...piezoelectric element, 400...temperature detection mechanism, 410...temperature detection section, 415...temperature detection resistor, 415A...first extension portion, 415B...second extension portion, 415C...third extension portion, 430...power supply section for temperature detection, 440...resistance measurement section for temperature detection, 450...temperature control section, 500...liquid ejection system, 510, 510b...liquid ejection head, 520...head control section, 5 50...ink tank, 552...tube, 560...transport mechanism, 562...transport roller, 564...transport rod, 566...transport motor, 570...movement mechanism, 572...carriage, 574...transport belt, 576...movement motor, 577...pulley, 580...control device, 582...CPU, 584...storage unit, 931...first temperature detection wiring, 932...second temperature detection wiring, 941...first humidity detection wiring, 942...second humidity detection wiring, AR...range, CP...center, EX...exposed portion, L1...first pressure chamber row, L2...second pressure chamber row, P...printing paper

Claims

1. A liquid ejection head, a piezoelectric element in which a first driving electrode, a piezoelectric body, and a second driving electrode are stacked in a stacking direction; a sealing substrate that forms a sealed space in which the piezoelectric element is provided; a protective film formed on the piezoelectric body in the stacking direction; a humidity detection unit formed on the piezoelectric body in the stacking direction, the humidity detection unit having a first detection electrode, an intermediate layer, and a second detection electrode; Equipped with The water absorption rate of the protective film is lower than the water absorption rate of the intermediate layer. Liquid ejection head.

2. 2. The liquid ejection head according to claim 1, the sealing substrate is bonded to the piezoelectric element and the humidity detector via an adhesive; The water absorption rate of the protective film is lower than the water absorption rate of the adhesive. Liquid ejection head.

3. 3. The liquid ejection head according to claim 2, The water absorption rate of the intermediate layer is lower than the water absorption rate of the adhesive. Liquid ejection head.

4. 3. The liquid ejection head according to claim 2, the intermediate layer is in contact with the adhesive; Liquid ejection head.

5. 5. The liquid ejection head according to claim 4, The intermediate layer has an exposed portion exposed to the sealed space. Liquid ejection head.

6. 2. The liquid ejection head according to claim 1, the sealing substrate is bonded to the piezoelectric element and the humidity detector via an adhesive; The adhesive is formed from the same material as the material constituting the intermediate layer. Liquid ejection head.

7. 7. The liquid ejection head according to claim 1, The water absorption rate of the intermediate layer is 1.8% or less. Liquid ejection head.

8. 7. The liquid ejection head according to claim 1, the sealing substrate has an air opening portion that opens the sealed space to the atmosphere, the distance between the atmospheric open portion and the protective film is greater than the distance between the atmospheric open portion and the intermediate layer; Liquid ejection head.

9. 7. The liquid ejection head according to claim 1, the first detection electrode and the second detection electrode are formed of the same material as the second drive electrode; Liquid ejection head.

10. 7. The liquid ejection head according to claim 1, the second driving electrode and the second detection electrode are provided at the same height in the stacking direction, one end of the sealing substrate in a direction intersecting the stacking direction is provided on the second detection electrode, and the other end is provided on the second driving electrode; Liquid ejection head.

11. 7. The liquid ejection head according to claim 1, the humidity detection section is formed in the stacking direction with the first detection electrode, the intermediate layer, and the second detection electrode in this order, the second detection electrode is formed by a conductive layer formed on the sealing substrate; Liquid ejection head.

12. A liquid ejection system, comprising: A liquid ejection head according to any one of claims 1 to 6, A control unit that calculates humidity by using a detection result of the humidity detection unit; Equipped with Liquid dispensing system.

Images