Liquid ejection head and liquid ejection device

Abstract

To provide a technique that can suppress loss of energy and attenuation of a signal in resistive wiring arranged inside a liquid discharge head, so as to enhance accuracy in detecting temperatures.SOLUTION: A liquid discharge head comprises: a pressure chamber substrate provided with a plurality of pressure chambers; a piezoelectric body that is driven to apply pressure to liquid in the pressure chambers; an upper electrode provided above the piezoelectric body to apply a voltage to the piezoelectric body; a lower electrode provided below the piezoelectric body to apply a voltage to the piezoelectric body; a detection resistor provided below the piezoelectric body to detect temperatures of the liquid in the pressure chambers; and first wiring portion electrically connected to the detection resistor. The first wiring portion comprises a first part extended above the piezoelectric body, and a second part provided in at least at a part of a through hole penetrating through the piezoelectric body and electrically connected to the detection resistor.SELECTED DRAWING: Figure 8

Description

[Technical Field]

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

[0002] A liquid ejection device is known that has a temperature detection unit on the side of a carriage on which a liquid ejection head is mounted (for example, Patent Document 1). This liquid ejection device changes the number of maintenance drive pulses applied to the piezoelectric element based on the environmental temperature detected by the temperature detection unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-104916 Summary of the Invention [Problem to be solved by the invention]

[0004] However, providing a temperature detection unit outside the liquid ejection head may reduce the accuracy of detecting the temperature of the ink inside the pressure chamber. Therefore, there is a demand for locating the temperature detection unit near the pressure chamber inside the liquid ejection head. The inventors have therefore discovered a new method for obtaining the temperature of the ink inside the pressure chamber by locating a resistive wiring inside the liquid ejection head and using the correspondence between the resistance value of the resistive wiring and the temperature. However, there is a demand for improving the accuracy of temperature detection using resistive wiring located inside the liquid ejection head. [Means for solving the problem]

[0005] According to a first aspect of the present disclosure, there is provided a liquid ejection head comprising: a pressure chamber substrate having a plurality of pressure chambers; a piezoelectric element driven to apply pressure to the liquid in the pressure chamber; an upper electrode provided above the piezoelectric element for applying a voltage to the piezoelectric element; a lower electrode provided below the piezoelectric element for applying a voltage to the piezoelectric element; a detection resistor provided below the piezoelectric element for detecting the temperature of the liquid in the pressure chamber; and a first wiring portion electrically connected to the detection resistor. The first wiring portion comprises a first portion extending above the piezoelectric element and a second portion provided in at least a portion of a through hole penetrating the piezoelectric element and electrically connected to the detection resistor.

[0006] According to a second aspect of the present disclosure, there is provided a liquid ejection device, comprising: the liquid ejection head according to the first aspect; and a control unit that controls the ejection operation of the liquid ejection head. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is an explanatory diagram showing a schematic configuration of a liquid ejection device according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a block diagram showing the functional configuration of the liquid ejection device. [Figure 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. [Figure 5] 5 is a cross-sectional view showing the VV position in FIG. 4. [Figure 6] FIG. 5 is an enlarged cross-sectional view showing a part of FIG. 4. [Figure 7] FIG. 7 is a cross-sectional view taken along the line VII-VII in FIG. 6. [Figure 8] FIG. 8 is a cross-sectional view taken along the line VIII-VIII in FIG. 6. [Figure 9] FIG. 3 is an explanatory diagram showing an enlarged plan view of the protective layer. [Figure 10] FIG. 10 is a cross-sectional view showing the structure in the vicinity of a contact hole of a liquid ejection head according to a second embodiment. [Figure 11] FIG. 10 is a cross-sectional view showing the structure in the vicinity of a contact hole of a liquid ejection head according to a third embodiment. [Figure 12] FIG. 10 is an explanatory diagram showing, in plan view, the structure in the vicinity of a contact hole of a liquid ejection head according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] A. First embodiment: FIG. 1 is an explanatory diagram showing a schematic configuration of a liquid ejection device 500 according to a first embodiment of the present disclosure. In this embodiment, the liquid ejection device 500 is an inkjet printer that ejects ink, an example of a liquid, onto printing paper P to form an image. Instead of printing paper P, the liquid ejection device 500 may eject ink onto any type of medium, such as a resin film or fabric. X, Y, and Z shown in FIG. 1 and subsequent figures represent three mutually orthogonal spatial axes. In this specification, the directions along these axes are also referred to as the X-axis direction, Y-axis direction, and Z-axis direction. When specifying a direction, positive and negative signs are used in combination, with a positive direction indicated as "+" and a negative direction indicated as "-." The direction indicated by the arrow in each figure is referred to as the + direction and the opposite direction as the - direction. In this embodiment, the Z direction coincides with the vertical direction, with the +Z direction indicating a vertically downward direction and the -Z direction indicating a vertically upward direction. Furthermore, when the positive and negative directions are not limited, the following description will be given assuming that the three X, Y, and Z are the X-axis, Y-axis, and Z-axis.

[0009] As shown in FIG. 1 , the liquid ejection device 500 includes a liquid ejection head 510, a temperature acquisition unit 400, an ink tank 550, a transport mechanism 560, a movement mechanism 570, and a control unit 580. The liquid ejection head 510 includes a detection resistor 401. In this embodiment, the temperature acquisition unit 400 is provided in the liquid ejection head 510. The liquid ejection head 510 has multiple nozzles formed therein and ejects ink of four colors, for example, black, cyan, magenta, and yellow, in the +Z direction to form an image on printing paper P. The liquid ejection head 510 is mounted on a carriage 572 and moves back and forth in the main scanning direction along 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 eject ink of any color, such as light cyan, light magenta, or white.

[0010] 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. Instead of the ink tank 550, a bag-shaped liquid pack made of a flexible film may be provided.

[0011] The transport mechanism 560 transports the printing 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 rotates the transport rod 564. The transport motor 566 rotates the transport rod 564, thereby transporting the printing paper P 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. Furthermore, a configuration may be provided with multiple transport mechanisms 560.

[0012] The movement mechanism 570 includes a carriage 572, a conveyor belt 574, a movement motor 576, and a pulley 577. The carriage 572 carries a liquid ejection head 510 that is ready to eject 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. When the movement motor 576 is driven to rotate, the conveyor belt 574 moves back and forth in the main scanning direction. As a result, the carriage 572, which is fixed to the conveyor belt 574, also moves back and forth in the main scanning direction.

[0013] The control unit 580 controls the entire liquid ejection device 500. The control unit 580 controls, for example, the reciprocating movement of the carriage 572 in the main scanning direction, the transport movement of the printing paper P in the sub-scanning direction, and the ejection movement of the liquid ejection head 510. The control unit 580 includes, for example, one or more processing circuits such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array), and one or more storage circuits such as a semiconductor memory.

[0014] Fig. 2 is a block diagram showing the functional configuration of the liquid ejection device 500. In Fig. 2, the configurations of the ink tank 550, the transport mechanism 560, and the movement mechanism 570 are omitted. The liquid ejection head 510 of this embodiment is provided with a piezoelectric element 300, a detection resistor 401, and a temperature acquisition unit 400.

[0015] The piezoelectric element 300 generates a pressure change in the ink within the pressure chamber of the liquid ejection head 510. The detection resistor 401 is a resistive wiring used to detect the temperature of the ink within the pressure chamber. The temperature acquisition unit 400 estimates the temperature of the ink within the pressure chamber by detecting the temperature of the detection resistor 401 using the characteristic that the electrical resistance value of resistive wiring made of metal, semiconductor, or the like changes with temperature. The temperature acquisition unit 400 includes a current application circuit 430, a voltage detection circuit 440, a temperature calculation unit 450, and a memory unit 460.

[0016] The current application circuit 430 applies a current to the detection resistor 401. In this embodiment, the current application circuit 430 is a constant current circuit that applies a predetermined constant current to the detection resistor 401. The voltage detection circuit 440 detects the voltage value of the voltage generated in the detection resistor 401 by the application of the current.

[0017] The storage unit 460 may be, for example, a nonvolatile memory such as an EEPROM that can be erased with an electrical signal, a nonvolatile memory such as a One-Time-PROM or an EPROM that can be erased with ultraviolet light, or a non-erasable nonvolatile memory such as a PROM. The storage unit 460 stores various programs for realizing the functions provided by the temperature acquisition unit 400 in this embodiment. The CPU of the temperature acquisition unit 400 executes the various programs stored in the storage unit 460, thereby functioning as the temperature calculation unit 450.

[0018] The temperature calculation unit 450 acquires the electrical resistance value of the detection resistor 401 and calculates the temperature of the pressure chamber. Specifically, the temperature calculation unit 450 acquires the resistance value of the detection resistor 401 based on the current value of the current applied to the detection resistor 401 from the current application circuit 430 and the voltage value of the voltage generated in the detection resistor 401 by the application of the current. The temperature calculation unit 450 calculates the temperature of the pressure chamber using the acquired resistance value of the detection resistor 401 and a temperature calculation formula stored in the storage unit 460. The temperature calculation formula indicates the correspondence relationship between the electrical resistance value of the detection resistor 401 and the temperature.

[0019] The temperature acquisition unit 400 outputs the detected temperature of the pressure chamber to the control unit 580. The control unit 580 outputs a drive signal based on the temperature of the pressure chamber acquired from the temperature acquisition unit 400 to the liquid ejection head 510 to drive the piezoelectric element 300, thereby controlling the ejection of ink onto the printing paper P.

[0020] The detailed configuration of the liquid ejection head 510 will be described with reference to FIGS. 3 to 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. FIG. 4 shows the configuration of the pressure chamber substrate 10 and its surroundings in the liquid ejection head 510. In FIG. 4, the sealing substrate 30 and the case member 40 are omitted from illustration to facilitate understanding of the technology. FIG. 5 is a cross-sectional view showing the VV position in FIG. 4.

[0021] As shown in FIG. 3, the liquid ejection head 510 includes a pressure chamber substrate 10, a communication plate 15, a nozzle plate 20, a compliance substrate 45, a sealing substrate 30, a case member 40, a vibration plate 50, and an intermediate substrate 120, and further includes a piezoelectric element 300 shown in FIG. 4. The pressure chamber substrate 10, the communication plate 15, the nozzle plate 20, the compliance substrate 45, the vibration plate 50, the piezoelectric element 300, the sealing substrate 30, and the case member 40 are laminated members, and are stacked to form the liquid ejection head 510. In the present disclosure, the direction in which the laminated members that form the liquid ejection head 510 are stacked is also referred to as the "stacking direction." In this embodiment, the stacking direction coincides with the Z-axis direction.

[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 , the pressure chamber substrate 10 has a plurality of pressure chambers 12 arranged along a predetermined direction. The direction in which the plurality of pressure chambers 12 are arranged is also referred to as the “arrangement direction.” In a plan view, 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 the present disclosure, “plan view” refers to a state in which an object is viewed along the stacking direction. 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 refers to a shape based on a rectangular shape with semicircular ends at both longitudinal ends, and includes a rounded rectangle, an ellipse, an egg shape, etc.

[0023] In this embodiment, the pressure chambers 12 are arranged in two rows, each with its arrangement direction aligned in the Y-axis direction. In the example of FIG. 4, two pressure chamber rows are formed in the pressure chamber substrate 10: a first pressure chamber row L1 with its arrangement direction aligned in the Y-axis direction, and a second pressure chamber row L2 with its arrangement direction aligned in the Y-axis direction. The first pressure chamber row L1 and the second pressure chamber row L2 are arranged on either side of the relay substrate 120. Specifically, the second pressure chamber row L2 is arranged on the opposite side of the first pressure chamber row L1, across the relay 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." In the example of FIG. 4, the intersecting direction is the X-axis direction, and the second pressure chamber row L2 is arranged in the -X direction relative to the first pressure chamber row L1, across the relay substrate 120. The pressure chambers 12 do not necessarily have to be arranged in a straight line, but may be arranged in a staggered arrangement along the Y-axis direction, in which every other pressure chamber 12 is staggered in the intersecting direction, for example.

[0024] The plurality of pressure chambers 12 belonging to the first pressure chamber row L1 and the plurality of pressure chambers 12 belonging to the second pressure chamber row L2 are arranged so that their positions in the arrangement direction coincide with each other and that they are adjacent to each other in the intersecting direction.

[0025] As shown in FIG. 3, a communication plate 15, a nozzle plate 20, and a compliance substrate 45 are stacked on the +Z direction side of the pressure chamber substrate 10. The communication plate 15 is a flat plate-like member made of, for example, a silicon substrate, a glass substrate, an SOI substrate, various ceramic substrates, or a metal substrate. Examples of metal substrates include a stainless steel substrate. As shown in FIG. 5, the communication plate 15 is provided with a nozzle communication passage 16, a first manifold portion 17, a second manifold portion 18, and a supply communication passage 19. It is preferable that the communication plate 15 be made of a material with approximately the same thermal expansion coefficient 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 due to differences in thermal expansion coefficients when the temperatures of the pressure chamber substrate 10 and the communication plate 15 change.

[0026] As shown in Fig. 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 through 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. Furthermore, 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.

[0027] As shown in FIG. 5 , the supply communication passage 19 is a flow path connected to a 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 a throttle portion 13. The throttle portion 13 is a flow path provided between the pressure chamber 12 and the pressure chamber supply path 14. The throttle portion 13 is a flow path whose inner wall protrudes further than 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 throttle portion 13 is set to have a higher flow path resistance than the pressure chamber 12 and the pressure chamber supply path 14. With the liquid ejection head 510 configured in this manner, it is possible to reduce or prevent ink from flowing back into the pressure chamber supply path 14 in the pressure chamber 12 even when pressure is applied to the pressure chamber 12 by the piezoelectric element 300 during ink ejection. There are multiple supply communication passages 19, which are arranged in the Y-axis direction, i.e., the arrangement direction, and each is 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 in the manifold 100 to each pressure chamber 12.

[0028] The nozzle plate 20 is provided on the opposite side of the communicating plate 15 from the pressure chamber substrate 10, i.e., on the surface of the communicating plate 15 in the +Z direction. The material of the nozzle plate 20 is not particularly limited, and examples thereof include a silicon substrate, a glass substrate, an SOI substrate, various ceramic substrates, and a metal substrate. Examples of metal substrates include a stainless steel substrate. The nozzle plate 20 can also be made of an organic material such as a polyimide resin. However, it is preferable to use a material for the nozzle plate 20 with approximately the same thermal expansion coefficient as the communicating plate 15. This makes it possible to suppress warping of the nozzle plate 20 and the communicating plate 15 due to differences in thermal expansion coefficients when the temperatures of the nozzle plate 20 and the communicating plate 15 change.

[0029] A plurality of nozzles 21 are formed in the nozzle plate 20. Each nozzle 21 is connected to a corresponding 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, each of which is provided with a plurality of nozzles 21. The two nozzle rows are provided corresponding to the first pressure chamber row L1 and the second pressure chamber row L2, respectively.

[0030] As shown in FIG. 5 , the compliance substrate 45 is provided together with the nozzle plate 20 on the side opposite the pressure chamber substrate 10 across the communicating plate 15, i.e., on the surface of the communicating plate 15 on the +Z direction side. The compliance substrate 45 is provided around the nozzle plate 20 and covers the openings of the first manifold section 17 and the second manifold section 18 provided in the communicating plate 15. In this embodiment, the compliance substrate 45 includes 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 forms an opening 48 that is completely removed in the thickness direction. Therefore, one side of the manifold 100 forms a compliance section 49 that is sealed only by the sealing film 46.

[0031] As shown in Fig. 5, a vibration plate 50 and a piezoelectric element 300 are laminated on the side of the pressure chamber substrate 10 opposite the nozzle plate 20, etc., i.e., on the surface of the pressure chamber substrate 10 on the -Z direction side. The piezoelectric element 300 flexes and deforms the vibration plate 50, causing a pressure change in the ink inside the pressure chamber 12. In Fig. 5, the configuration of the piezoelectric element 300 is shown in a simplified manner to make the technology easier to understand. The vibration plate 50 is provided on the +Z direction side of the piezoelectric element 300, and the pressure chamber substrate 10 is provided on the +Z direction side of the vibration plate 50.

[0032] As shown in FIG. 5 , a sealing substrate 30 having substantially the same size as the pressure chamber substrate 10 in a plan view is bonded to the surface of the pressure chamber substrate 10 on the −Z direction side with an adhesive or the like. 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 concave space defined by the ceiling portion 30T and the wall portion 30W, and protects the active portions of the piezoelectric elements 300. The holding portions 31 of the sealing substrate 30 are provided for each column of the piezoelectric elements 300 arranged in the arrangement direction. In this embodiment, two holding portions 31 are formed adjacent to each other in the X-axis direction. The through-hole 32 extends along the Y-axis direction between the two holding portions 31 and penetrates the sealing substrate 30 along the Z-axis direction.

[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 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 deep enough to store the pressure chamber substrate 10 and the sealing substrate 30. The third manifold section 42 is a space formed in the case member 40 on both sides 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 an elongated shape that is continuous along the Y-axis direction. The supply port 44 communicates with the manifolds 100 and supplies ink to each manifold 100. The connection port 43 is a through hole that communicates with the through hole 32 of the sealing substrate 30, and an intermediate substrate 120 is inserted through the through hole 43.

[0035] 5, ink supplied from the ink tank 550 shown in Fig. 1 is taken in through the supply port 44 shown in Fig. 5, and the internal flow paths from the manifold 100 to the nozzles 21 are filled with ink. Then, a voltage based on a drive signal is applied to each of the piezoelectric elements 300 corresponding to the plurality of pressure chambers 12. This causes the vibration plate 50 to flex and deform together with the piezoelectric elements 300, increasing the pressure inside each pressure chamber 12 and causing ink droplets to be ejected from each nozzle 21.

[0036] The configurations of the piezoelectric element 300 and the detection resistor 401 will be described with reference to Figures 4 and 5 as well as Figures 6 to 8. Figure 6 is an enlarged cross-sectional view showing the range AR in Figure 4. Figure 7 is a cross-sectional view showing the position VII-VII in Figure 6. Figure 8 is a cross-sectional view showing the position VIII-VIII in Figure 6. As shown in Figure 6, the liquid ejection head 510 has, on the -Z direction side of the pressure chamber substrate 10, not only the vibration plate 50 and the piezoelectric element 300, but also individual lead electrodes 91, common lead electrodes 92, measurement lead electrodes 93, and the detection resistor 401.

[0037] As shown in FIG. 7, the diaphragm 50 includes an elastic film 55 made of silicon oxide (SiO2) provided on the pressure chamber substrate 10, and an insulating film 56 made of zirconium oxide (ZrO2) provided on the elastic film 55. The 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 elastic film 55 forms the surface on the -Z direction side of the flow paths of the pressure chambers 12, etc. Note that the diaphragm 50 may be made up of, for example, either the elastic film 55 or the insulating film 56, or may include other films in addition to the elastic film 55 and the insulating film 56. Examples of materials for the other films include silicon and silicon nitride.

[0038] The piezoelectric element 300 applies pressure to the pressure chamber 12. As shown in Fig. 7, the piezoelectric element 300 has a first electrode 60, a piezoelectric body 70, and a second electrode 80. As shown in Fig. 7, the first electrode 60, the piezoelectric body 70, and the second electrode 80 are stacked in this order from the +Z direction side to the -Z direction side along the stacking direction. The piezoelectric body 70 is provided between the first electrode 60 and the second electrode 80 in the stacking direction in which the first electrode 60, the second electrode 80, and the piezoelectric body 70 are stacked.

[0039] The first electrode 60 and the second electrode 80 are both electrically connected to the relay substrate 120 shown in FIG. 5. The first electrode 60 and the second electrode 80 apply a voltage corresponding to a drive signal to the piezoelectric body 70. A portion of the piezoelectric element 300 where piezoelectric strain occurs in the piezoelectric body 70 when a voltage is applied between the first electrode 60 and the second electrode 80 is also called an active portion. The active portion is a portion of the piezoelectric element 300 where the piezoelectric body 70 is sandwiched between the first electrode 60 and the second electrode 80.

[0040] A driving voltage that varies depending on the amount of ink ejected is supplied to the first electrode 60, and a constant reference voltage signal is supplied to the second electrode 80 regardless of the amount of ink ejected. When the active part of the piezoelectric element 300 is driven, a potential difference occurs between the first electrode 60 and the second electrode 80, causing the piezoelectric body 70 to deform. The part of the piezoelectric element 300 that actually displaces in the Z-axis direction when it is driven is also called the flexible part. The part of the piezoelectric element 300 that faces the pressure chamber 12 in the Z-axis direction is the flexible part. The deformation of the piezoelectric body 70 causes the vibration plate 50 to deform or vibrate, changing the volume of the pressure chamber 12. The change in volume of the pressure chamber 12 applies pressure to the ink contained in the pressure chamber 12, causing ink to be ejected from the nozzle 21 via the nozzle communication passage 16.

[0041] The first electrodes 60 are individual electrodes provided for the multiple pressure chambers 12. As shown in FIG. 7, the first electrodes 60 are lower electrodes provided on the opposite side of the piezoelectric body 70 from the second electrode 80, i.e., on the +Z direction side of the piezoelectric body 70, below the piezoelectric body 70. The thickness of the first electrodes 60 is, for example, approximately 80 nanometers. The first electrodes 60 are formed from a conductive material, for example, a metal such as platinum (Pt), iridium (Ir), gold (Au), or titanium (Ti), or a conductive metal oxide such as indium tin oxide (ITO). The first electrodes 60 may be formed by laminating multiple materials, such as platinum (Pt), iridium (Ir), gold (Au), or titanium (Ti). In this embodiment, platinum (Pt) is used as the first electrode 60.

[0042] As shown in FIG. 4, the piezoelectric body 70 has a predetermined width in the X-axis direction and extends along the arrangement direction of the pressure chambers 12, i.e., the Y-axis direction. As shown in FIG. 7, an end 70a of the piezoelectric body 70 in the +X direction is covered with a wiring portion 96 formed at the same time as the individual lead electrode 91. The thickness of the piezoelectric body 70 is, for example, approximately 1000 to 4000 nanometers. The piezoelectric body 70 may be a crystalline film with a perovskite structure, so-called perovskite crystal, made of a ferroelectric ceramic material exhibiting electromechanical transduction and formed on the first electrode 60. Examples of the material for the piezoelectric body 70 include ferroelectric piezoelectric materials such as lead zirconate titanate (PZT), and materials 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. In this embodiment, lead zirconate titanate (PZT) is used as the piezoelectric body 70.

[0043] The material of the piezoelectric body 70 is not limited to lead-based piezoelectric materials containing lead, and lead-free piezoelectric materials can also be used. Examples of lead-free piezoelectric materials include bismuth ferrite ((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 ((Bi1 / 2K1 / 2)TiO3, abbreviated as "BKT"), bismuth sodium titanate ((Bi1 / 2Na1 / 2)TiO3, abbreviated as "BNT"), manganese dioxide (MgO3), ... Examples include bismuth phosphate (BiMnO3, abbreviated as "BM"), composite oxides containing bismuth, potassium, titanium, and iron and having a perovskite structure (x[(BixK1-x)TiO3]-(1-x)[BiFeO3], abbreviated as "BKT-BF"), composite oxides containing bismuth, iron, barium, and titanium and having a perovskite structure ((1-x)[BiFeO3]-x[BaTiO3], abbreviated as "BFO-BT"), and oxides to which metals such as manganese, cobalt, and chromium are added ((1-x)[Bi(Fe1-yMy)O3]-x[BaTiO3] (M is Mn, Co, or Cr)).

[0044] As shown in FIG. 4, the second electrode 80 is a common electrode provided for the multiple pressure chambers 12. The second electrode 80 has a predetermined width in the X-axis direction and extends along the arrangement direction of the pressure chambers 12, i.e., the Y-axis direction. As shown in FIG. 7, the second electrode 80 is an upper electrode provided on the opposite side of the piezoelectric body 70 from the first electrode 60, i.e., on the −Z-direction side of the piezoelectric body 70, above the piezoelectric body 70. The material of the second electrode 80 is not particularly limited, but, like the first electrode 60, conductive materials such as metals such as platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti), and conductive metal oxides such as indium tin oxide (ITO) are used. Alternatively, the second electrode 80 may be formed by stacking multiple materials such as platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti). In this embodiment, iridium (Ir) is used as the second electrode 80.

[0045] As shown in FIG. 7 , a wiring portion 85 is provided further toward the −X direction than the −X direction end portion 80b of the second electrode 80. The wiring portion 85 is formed in the same layer as the second electrode 80 but is electrically discontinuous with the second electrode 80. The wiring portion 85 is formed from the −X direction end portion 70b of the piezoelectric body 70 to the −X direction end portion 60b of the first electrode 60, with a gap between the wiring portion 85 and the end portion 80b of the second electrode 80. The −X direction end portion 60b of the first electrode 60 extends further to the outside than the end portion 70b of the piezoelectric body 70. A plurality of wiring portions 85 are provided for each piezoelectric element 300, and are arranged at predetermined intervals along the Y axis direction. The wiring portion 85 is preferably formed in the same layer as the second electrode 80. This simplifies the manufacturing process of the wiring portion 85 and reduces costs. However, the wiring portion 85 may be formed in a layer separate from the second electrode 80.

[0046] 6 and 7, an individual lead electrode 91 is electrically connected to the first electrode 60, which is an individual electrode, and an extension portion 92a and an extension portion 92b of a common lead electrode 92 are electrically connected to the second electrode 80, which is a common electrode. The individual lead electrode 91 and the common lead electrode 92 function as drive wiring for applying a voltage to the piezoelectric body 70 to drive the piezoelectric body 70. In this embodiment, the power supply circuit for supplying power to the piezoelectric body 70 via the drive wiring and the current application circuit 430 for supplying power to the detection resistor 401 are different circuits.

[0047] The individual lead electrode 91 and the common lead electrode 92 are made of a conductive material, such as gold (Au), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), platinum (Pt), or aluminum (Al). In this embodiment, gold (Au) is used for the individual lead electrode 91 and the common lead electrode 92. The individual lead electrode 91 and the common lead electrode 92 may also have an adhesion layer that improves adhesion to the first electrode 60, the second electrode 80, and the diaphragm 50.

[0048] The individual lead electrode 91 and the common lead electrode 92 are formed in the same layer so as to be electrically discontinuous. This simplifies the manufacturing process and reduces costs compared to when the individual lead electrode 91 and the common lead electrode 92 are formed separately. The individual lead electrode 91 and the common lead electrode 92 may be formed in different layers.

[0049] As shown in FIG. 6, an individual lead electrode 91 is provided for each first electrode 60. As shown in FIG. 7, the individual lead electrode 91 is connected to the vicinity of the end 60b of the first electrode 60 via a wiring portion 85, and is drawn out in the −X direction onto the diaphragm 50. The individual lead electrode 91 electrically connected to the first electrode 60 is also referred to as a “second wiring portion.” The individual lead electrode 91 is electrically connected to the −X direction end 60b of the first electrode 60, which is drawn out further to the outside than the end 70b of the piezoelectric body 70. The wiring portion 85 may be omitted, and the individual lead electrode 91 may be directly connected to the end 60b of the first electrode 60.

[0050] 4, the common lead electrode 92 extends along the Y-axis direction, is bent at both ends in the Y-axis direction, and is drawn out in the −X direction. The common lead electrode 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 individual lead electrodes 91 and the common lead electrode 92 extend so as to be exposed in through holes 32 formed in the sealing substrate 30, and are electrically connected to the relay substrate 120 within the through holes 32.

[0051] The relay substrate 120 is formed of, for example, a flexible substrate (FPC: Flexible Printed Circuit). The relay substrate 120 has a plurality of wirings formed thereon for connection to the control unit 580 and a power supply circuit (not shown). Note that instead of an FPC, any flexible substrate such as an FFC (Flexible Flat Cable) may be used. An integrated circuit 121 having a switching element is mounted on the relay substrate 120. A signal for driving the piezoelectric element 300 is input to the integrated circuit 121. The integrated circuit 121 controls the timing at which the signal for driving the piezoelectric element 300 is supplied to the first electrode 60 based on the input signal. This controls the timing at which the piezoelectric element 300 is driven and the amount of drive of the piezoelectric element 300.

[0052] 4, a detection resistor 401 is further provided on the surface of the diaphragm 50 on the -Z direction side. As shown in Fig. 4, in this embodiment, the detection resistor 401 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 detection resistor 401 is electrically connected to the measurement lead electrode 93, which is the first wiring portion, and includes a first extension portion 401A extending along the intersecting direction on an outer side in the -Y direction of the multiple pressure chambers 12, a second extension portion 401B continuing from the second extension portion 401B and extending along the arrangement direction, and a third extension portion 401C extending along the intersecting direction on an outer side in the +Y direction of the multiple pressure chambers 12.

[0053] 4, the second extending portion 401B of the detection resistor 401 is formed in a so-called meandering pattern, which makes multiple trips along the arrangement direction near the first pressure chamber row L1 and the second pressure chamber row L2. This configuration can improve the accuracy with which the detection resistor 401 detects the temperature of ink in the pressure chambers 12. However, the second extending portion 401B of the detection resistor 401 is not limited to a meandering pattern and may be formed in any shape, such as a straight line.

[0054] 6 and 7, the detection resistor 401 is arranged so as to pass near the ink flow path in the pressure chamber substrate 10. Of the detection resistor 401, the second extension portion 401B is arranged so as to pass on the -Z direction side of the vibration plate 50 with respect to the throttle portion 13 near each pressure chamber 12. For this reason, the second extension portion 401B can be considered to be the portion that can contribute most to detecting the temperature of the ink in the pressure chamber 12. The first extension portion 401A and the third extension portion 401C are farther away from the pressure chamber 12, and can be considered to be portions that contribute less to temperature detection than the second extension portion 401B.

[0055] FIG. 6 schematically illustrates a first distance D1, which is the shortest distance from the first extension portion 401A to the multiple pressure chambers 12, and a second distance D2, which is the shortest distance from the second extension portion 401B to the multiple pressure chambers 12. In this embodiment, the first distance D1 is longer than the second distance D2. The longer the wiring length, the higher the resistance value, which increases the likelihood of noise, such as energy loss and electrical signal attenuation. Therefore, in order to suppress noise, such as energy loss and electrical signal attenuation, it is preferable that the wiring lengths of the first extension portion 401A and the third extension portion 401C, which are spaced apart from the pressure chambers 12, are as short as possible. In the present disclosure, the multiple pressure chambers 12 refer to those that are connected to a nozzle 21 and that are provided with a piezoelectric element 300. For example, so-called dummy pressure chambers, such as pressure chambers that are not connected to a nozzle 21 and pressure chambers that are not provided with a corresponding piezoelectric element 300, are considered to be different from the "multiple pressure chambers 12" in the present disclosure. For example, if the shortest distance from the first extending portion 401A to the "plurality of pressure chambers 12" that contribute to the ejection of liquid is the first distance D1, and the first distance D1 is longer than the second distance D2, the shortest distance from the first extending portion 401A to the dummy pressure chamber may be shorter than the second distance D2. In this case, there is a risk that noise will be generated in the dummy pressure chamber because the distance from the first extending portion 401A is short, but since the dummy pressure chamber does not contribute to ejection in the first place, this is not a problem, and rather the effect of reducing the size of the entire liquid ejection head 510 can be obtained.

[0056] The material of the detection resistor 401 is a material whose electrical resistance value is temperature dependent, and can be, for example, gold (Au), platinum (Pt), iridium (Ir), aluminum (Al), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), etc. Of these, platinum (Pt) is suitable for use as the material of the detection resistor 401 from the viewpoints of its large temperature-dependent change in electrical resistance, stability, and high accuracy.

[0057] 7, in this embodiment, the detection resistor 401 is formed in the same layer as the first electrode 60 in the stacking direction, and is electrically discontinuous with the first electrode 60. In this embodiment, the detection resistor 401 is formed together with the first electrode 60 in the process of forming the first electrode 60. The material of the detection resistor 401 is platinum (Pt), the same as the first electrode 60, and the thickness of the detection resistor 401 is about 80 nanometers, the same as the first electrode 60. However, this is not limiting, and the detection resistor 401 may be formed separately from the first electrode 60, or may be formed together with a layer different from that of the first electrode 60.

[0058] 7, in this embodiment, a low thermal conductive layer 402 is laminated on the detection resistor 401. Specifically, the low thermal conductive layer 402 is provided on the surface of the detection resistor 401 opposite to the surface facing the pressure chamber substrate 10, i.e., on the surface on the -Z direction side. The low thermal conductive layer 402 has a lower thermal conductivity than the detection resistor 401.

[0059] The low thermal conductive layer 402 is laminated on top of the detection resistor 401 and is covered together with the detection resistor 401 by the piezoelectric element 70. As will be described later, from the viewpoint of facilitating electrical connection between the measurement lead electrode 93 and the detection resistor 401 via the contact hole 93H, the low thermal conductive layer 402 is preferably made of a conductive material such as metal. By providing a layer with low thermal conductivity on the surface of the detection resistor 401 opposite to the surface facing the pressure chamber substrate 10, it is possible to prevent heat transferred from the ink in the pressure chamber 12 to the detection resistor 401 from being dissipated from the surface opposite to the surface facing the pressure chamber substrate 10. The thicker the low thermal conductive layer 402, the more reliably it is suppressed. The low thermal conductive layer 402 does not necessarily need to be in contact with the detection resistor 401, and for example, an adhesion layer such as iridium (Ir) may be disposed between the detection resistor 401 and the low thermal conductive layer 402 to improve adhesion between the detection resistor 401 and the low thermal conductive layer 402. The low thermal conductive layer 402 can be omitted, and in the following description, the configuration of the low thermal conductive layer 402 will be omitted unless otherwise specified.

[0060] 6 shows the measurement lead electrode 93. The measurement lead electrode 93 is a first wiring portion electrically connected to the detection resistor 401. In this embodiment, the measurement lead electrode 93 is formed in the same layer as the individual lead electrode 91 and the common lead electrode 92, and is formed so as to be electrically discontinuous with each other. The detection resistor 401 is electrically connected to the relay board 120 by the measurement lead electrode 93, which enables the temperature calculation unit 450 to detect the electrical resistance value of the detection resistor 401.

[0061] In this embodiment, the electrical resistance per unit length of the detection resistor 401 is set to be higher than the electrical resistance per unit length of the measurement lead electrode 93. The electrical resistance per unit length depends on the cross-sectional area and material of the wiring. The measurement lead electrode 93 is made of a conductive material, such as gold (Au), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), platinum (Pt), or aluminum (Al). In this embodiment, gold (Au), which has a lower electrical resistance than the detection resistor as platinum (Pt), is used for the measurement lead electrode 93. The material of the measurement lead electrode 93 is the same as that of the individual lead electrode 91 and the common lead electrode 92. The measurement lead electrode 93 may be made of any material other than gold (Au) and may be made of a different material from that of the individual lead electrode 91 and the common lead electrode 92. Instead of changing the material, the cross-sectional area of ​​the wiring may be increased so that the electrical resistance value of the measurement lead electrode 93 is set lower than that of the detection resistor 401 .

[0062] As shown in FIG. 8 , the measurement lead electrode 93 includes wiring portions 93a and 93b extending above the piezoelectric body 70 and a contact hole 93H provided in a through hole 70H that penetrates the piezoelectric body 70. The through hole 70H can be formed, for example, by ion milling when forming the piezoelectric body 70. The wiring portion 93a is electrically connected to the detection resistor 401 through the contact hole 93H. Although not shown, the wiring portion 93b is similarly connected to the wiring portion 93b through the contact hole 93H. The wiring portions 93a and 93b are also referred to as the “first portion,” and the contact hole 93H is also referred to as the “second portion.” The contact hole 93H may be provided in only one of the wiring portions 93a and 93b. As shown in Figures 6 and 8, the contact hole 93H is located inside the wall portion 30W of the sealing substrate 30 and overlaps with the ceiling portion 30T, and the connection portion between the wiring portion 93a and the detection resistor 401 is accommodated in the holding portion 31 of the sealing substrate 30.

[0063] 8 shows a region RA where the piezoelectric body 70 and the wiring portion 93a serving as the first wiring portion overlap when viewed along the stacking direction. Also shown within the region RA are a range R1 where the detection resistor 401 is not disposed and a range R2 where the detection resistor 401 is disposed. In this embodiment, the range R2 where the detection resistor 401 is disposed is set to be narrower than the range R1 where the detection resistor 401 is not disposed. By narrowing the overlapping portion between the detection resistor 401 and the wiring portion 93a in this manner, the first extension portion 401A of the detection resistor 401 is set to be smaller.

[0064] As shown in FIG. 8 , in this embodiment, a protective layer 94 is further provided between the contact hole 93H and the detection resistor 401. The protective layer 94 is made of the same material as the second electrode 80, which is iridium (Ir) in this embodiment. The protective layer 94 is conductive, and the contact hole 93H of the measurement lead electrode 93 is electrically connected to the detection resistor 401 via the protective layer 94. The protective layer 94 is laminated on top of the detection resistor 401 exposed from the through hole 70H of the piezoelectric body 70, thereby protecting the detection resistor 401 from damage caused by, for example, etching during the formation of the second electrode 80. This suppresses variations in the film thickness of the detection resistor 401 and reduces or prevents a decrease in temperature detection accuracy.

[0065] FIG. 9 is an explanatory diagram showing an enlarged plan view of the protective layer 94. FIG. 9 schematically illustrates the measurement lead electrode 93, the protective layer 94, and the detection resistor 401. Note that in FIG. 9, the protective layer 94 and the contact hole 93H are hatched to facilitate understanding of the technology. In this embodiment, as shown in FIG. 9, the area S1 of the protective layer 94 is designed to be larger than the area S2 of the contact hole 93H in a plan view. In this manner, the protective layer 94 is configured to cover the through hole 70H so that the detection resistor 401 in the through hole 70H is not exposed. This reduces damage to the detection resistor 401 during manufacturing, such as by etching, compared to when at least a portion of the detection resistor 401 is not covered by the protective layer 94 and is exposed through the through hole 70H.

[0066] As described above, the liquid ejection head 510 of this embodiment includes the pressure chamber substrate 10 having a plurality of pressure chambers 12 formed therein, the piezoelectric element 70 that is driven to apply pressure to the ink in the pressure chambers 12, the second electrode 80 that is provided above the piezoelectric element 70 and serves as an upper electrode for applying a voltage to the piezoelectric element 70, the first electrode 60 that is provided below the piezoelectric element 70 and serves as a lower electrode for applying a voltage to the piezoelectric element 70, the detection resistor 401 that is provided below the piezoelectric element 70 and serves to detect the temperature of the ink in the pressure chambers 12, and the measurement lead electrode 93 that serves as a first wiring portion electrically connected to the detection resistor 401. The measurement lead electrode 93 includes a wiring portion 93a that serves as a first portion extending above the piezoelectric element 70, and a contact hole 93H that serves as a second portion electrically connected to the detection resistor 401 and that is provided in at least a part of the through hole 32 that penetrates the piezoelectric element 70. By electrically connecting the detection resistor 401 and the measurement lead electrode 93 using the through hole 70H of the piezoelectric body 70, the wiring length of the detection resistor 401 can be shortened compared to a structure in which the detection resistor 401 extends from the end 70b of the piezoelectric body 70 to the outside and is electrically connected to the measurement lead electrode 93. This reduces energy loss and signal attenuation in the detection resistor 401, thereby improving the accuracy of temperature detection. Furthermore, using the through hole 70H of the piezoelectric body 70 allows the detection resistor 401 and the measurement lead electrode 93 to be electrically connected in a simpler manner than when the detection resistor 401 is exposed from the end 70b of the piezoelectric body 70 by, for example, etching.

[0067] The liquid ejection head 510 of this embodiment further includes an individual lead electrode 91 and a common lead electrode 92 as second wiring portions electrically connected to the first electrode 60 as a lower electrode. The individual lead electrode 91 and the common lead electrode 92 are electrically connected to a lower electrode that is drawn out beyond the end 70b of the piezoelectric body 70. By drawing the lower electrode out beyond the end 70b of the piezoelectric body 70, the contact area between the lower electrode and the piezoelectric body 70 can be increased. As a result, the area of ​​the active portion of the piezoelectric element 300 is increased, and ink ejection performance can be improved.

[0068] According to the liquid ejection head 510 of this embodiment, when viewed along the stacking direction, within the region RA where the piezoelectric body 70 and the measurement lead electrode 93 overlap, the range R2 where the detection resistor 401 is arranged is narrower than the range R1 where the detection resistor 401 is not arranged. By narrowing the overlapping portion between the detection resistor 401 and the wiring portion 93a, the first extension portion 401A of the detection resistor 401 is set to be small. Therefore, energy loss and signal attenuation in the detection resistor 401 can be suppressed, and the temperature detection accuracy can be improved.

[0069] The liquid ejection head 510 of this embodiment further includes a sealing substrate 30 having a wall portion 30W and a ceiling portion 30T, and the wall portion 30W and the ceiling portion 30T protect the active portion of the piezoelectric element 70. When viewed along the stacking direction, the contact hole 93H is provided at a position overlapping with the ceiling portion 30T. Covering with the sealing substrate 30 protects the electrical connection portion between the wiring portion 93a and the detection resistor 401, and can suppress problems such as electrical open circuits and short circuits between the wiring portion 93a and the detection resistor 401.

[0070] The liquid ejection head 510 of this embodiment further includes a protective layer 94 formed of the same material as the upper electrode between the contact hole 93H and the detection resistor 401. The contact hole 93H is electrically connected to the detection resistor 401 via the protective layer 94. By laminating the protective layer 94 on the upper part of the detection resistor 401 exposed from the through-hole 70H of the piezoelectric body 70, the detection resistor 401 can be protected from damage caused by, for example, etching when forming the second electrode 80. This prevents variations in the film thickness of the detection resistor 401 and prevents a decrease in temperature detection accuracy.

[0071] According to the liquid ejection head 510 of this embodiment, when viewed along the stacking direction, the through hole 70H is covered with the protective layer 94 having an area S1 larger than the area S2 of the contact hole 93H. By configuring the protective layer 94 to cover the detection resistor 401 exposed from the through hole 70H, damage to the detection resistor 401 due to etching during the manufacturing process can be reduced compared to when at least a portion of the detection resistor 401 is exposed from the through hole 70H.

[0072] According to the liquid ejection head 510 of this embodiment, the electrical resistance value per unit length of the detection resistor 401 is higher than the electrical resistance value per unit length of the measurement lead electrode 93. Increasing the electrical resistance value of the detection resistor 401 improves the accuracy of temperature detection, and furthermore, suppressing energy loss and signal attenuation in the measurement lead electrode 93, which do not directly contribute to temperature detection, can further increase the accuracy of temperature detection.

[0073] According to the liquid ejection head 510 of this embodiment, when the direction in which the multiple pressure chambers 12 are arranged is defined as the arrangement direction and the direction orthogonal to both the stacking direction and the stacking direction is defined as the intersecting direction, the detection resistor 401 is electrically connected to the measurement lead electrode 93 and includes a first extension portion 401A that extends along the intersecting direction outside the multiple pressure chambers 12, and a second extension portion 401B that is continuous with the first extension portion 401A and extends along the arrangement direction. By arranging the second extension portion 401B along the arrangement direction of the multiple pressure chambers 12, the detection resistor 401 can be efficiently arranged around the multiple pressure chambers 12 from the standpoint of temperature detection of the multiple pressure chambers 12.

[0074] According to the liquid ejection head 510 of this embodiment, when the shortest distance from the first extension portion 401A to the multiple pressure chambers 12 is defined as a first distance D1 and the shortest distance from the second extension portion 401B to the multiple pressure chambers 12 is defined as a second distance D2, the first distance D1 is longer than the second distance D2. By arranging the second extension portion 401B, which is arranged in the arrangement direction of the pressure chambers 12, closer to the multiple pressure chambers 12 than the first extension portion 401A, which is connected to the measurement lead electrode 93, the detection resistor 401 can be arranged around the multiple pressure chambers 12 more efficiently from the viewpoint of detecting the temperature of the multiple pressure chambers 12.

[0075] The liquid ejection device 500 of this embodiment includes the above-described liquid ejection head 510 and a control unit 580 that controls the ejection operation of the liquid ejection head 510. Therefore, it is possible to provide a liquid ejection device 500 that suppresses energy loss and signal attenuation in the detection resistor 401 and has high temperature detection accuracy.

[0076] B. Second embodiment: 10 is a cross-sectional view showing the structure of the vicinity of contact hole 93H2 of liquid ejection head 510 according to the second embodiment of the present disclosure. Liquid ejection head 510 of the second embodiment differs from liquid ejection head 510 of the first embodiment in that it has contact hole 93H2 instead of contact hole 93H, and in that it has protective layer 94b instead of protective layer 94 between contact hole 93H2 and detection resistor 401. Other configurations are the same as those of liquid ejection head 510 of the first embodiment.

[0077] The protective layer 94b differs from the protective layer 94 in that it includes an opening 94T, but otherwise has the same configuration as the protective layer 94. In this embodiment, the contact hole 93H2 of the measurement lead electrode 93 is electrically connected to the detection resistor 401 through a portion of the protective layer 94b, and is also electrically connected to the detection resistor 401 through the protective layer 94b, which abuts against the detection resistor 401 through the opening 94T. In this way, when the protective layer 94b is provided, the contact hole 93H2 is not limited to being electrically connected to the detection resistor 401 only through the protective layer 94b. It may be electrically connected to the detection resistor 401 through a portion of the protective layer 94b, or it may be electrically connected to the detection resistor 401 by abutting the contact hole 93H2 against the detection resistor 401 instead of or in addition to the protective layer 94b.

[0078] As a method for forming the opening 94T, for example, similar to the protective layer 94 in the first embodiment, a protective layer 94b is first formed to cover the detection resistor 401 so that the detection resistor 401 in the through hole 70H is not exposed when the second electrode 80 is formed. The opening 94T can be formed by removing a portion of the formed protective layer 94b located at the bottom of the through hole 70H by etching, for example, ion milling.

[0079] According to the liquid ejection head 510 of this embodiment, the contact hole 93H2 is electrically connected to the detection resistor 401 through the opening 94T provided in the protective layer 94b. Therefore, while providing the protective layer 94b, the contact hole 93H2 can be brought into contact with the detection resistor 401, reducing the electrical resistance between the detection resistor 401 and the contact hole 93H2 and improving the temperature detection accuracy. Furthermore, for example, by forming the opening 94T after forming the second electrode 80, damage to the detection resistor 401 due to etching or the like during the formation of the second electrode 80 can be suppressed by the protective layer 94b covering the detection resistor 401, thereby suppressing the occurrence of variations in the film thickness of the detection resistor 401.

[0080] C. Third embodiment: 11 is a cross-sectional view showing the structure near the contact hole 93H3 of a liquid ejection head 510 according to the third embodiment. The liquid ejection head 510 according to the second embodiment differs from the liquid ejection head 510 according to the first embodiment in that it has a contact hole 93H3 instead of the contact hole 93H and in that it does not have a protective layer 94 between the contact hole 93H3 and the detection resistor 401. Other than that, the configuration is the same as that of the liquid ejection head 510 according to the first embodiment.

[0081] According to the liquid ejection head 510 of this embodiment, the contact hole 93H3 is provided by filling the through hole 70H of the piezoelectric body 70. Therefore, compared to a configuration in which the liquid ejection head 510 includes the protective layer 94, the area in which the contact hole 93H3 abuts against the detection resistor 401 is increased, thereby reducing the electrical resistance between the detection resistor 401 and the contact hole 93H3 and improving the temperature detection accuracy.

[0082] D. Fourth embodiment: 12 is an explanatory diagram showing, in plan view, the structure in the vicinity of the contact hole 93H4 of a liquid ejection head 510 according to the fourth embodiment. The liquid ejection head 510 according to the fourth embodiment differs from the liquid ejection head 510 according to the first embodiment in that it has a contact hole 93H4 instead of the contact hole 93H and in that it does not have a protective layer 94 between the contact hole 93H4 and the detection resistor 401. Other than that, the configuration is the same as that of the liquid ejection head 510 according to the first embodiment. In FIG. 12, the contact hole 93H4 is hatched to facilitate understanding of the technology.

[0083] 12, in a plan view, the contact hole 93H4 is formed only in the center of the through hole 70H in the Y-axis direction, across the entire width in the X-axis direction. In this way, the contact hole 93H4 does not have to fill the through hole 70H, but may be formed in a part of the through hole 70H. With the liquid ejection head 510 configured in this way, the measurement lead electrode 93 and the detection resistor 401 can be electrically connected by the contact hole 93H4 shaped according to the shape of the measurement lead electrode 93. Note that the position at which the contact hole 93H4 is formed in the through hole 70H is not limited to the example in FIG. 12, and the contact hole 93H4 may be formed at any position within the through hole 70H.

[0084] E. Other Embodiments: (E1) In the above embodiments, an example was shown in which the second electrode 80 serving as a common electrode is provided above the piezoelectric body 70, and the first electrode 60 serving as an individual electrode is provided below the piezoelectric body 70. However, the common electrode may be a lower electrode provided below the piezoelectric body 70, and the individual electrodes may be upper electrodes provided above the piezoelectric body 70. In this case, it is preferable that the detection resistor 401 is formed using the same material as the lower electrode serving as a common electrode provided below the piezoelectric body 70. This allows the detection resistor 401 to be formed in the process of forming the common electrode, simplifying the manufacturing process and reducing costs.

[0085] (E2) In the above embodiments, the detection resistor 401 is made of platinum (Pt), the same material as the first electrode 60. However, the detection resistor 401 is not limited to being made of an individual electrode, and may be made of the same material as the common electrode or the drive wiring. For example, the detection resistor 401 may be made of the same material as the second electrode 80, which is a common electrode. According to the liquid ejection head 510 of this embodiment, for example, the detection resistor 401 can be formed in the process of forming the second electrode 80, thereby simplifying the manufacturing process and reducing costs. Furthermore, the detection resistor 401 may be made of the same material as the individual lead electrode 91 and the common lead electrode 92, which are the drive wiring. According to the liquid ejection head 510 of this embodiment, for example, the detection resistor 401 can be formed in the process of forming the individual lead electrode 91 and the common lead electrode 92, thereby simplifying the manufacturing process and reducing costs.

[0086] F. Other Forms: The present disclosure is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit thereof. For example, the technical features in the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted.

[0087] (1) According to one aspect of the present disclosure, a liquid ejection head is provided. The liquid ejection head includes a pressure chamber substrate having a plurality of pressure chambers, a piezoelectric element driven to apply pressure to the liquid in the pressure chamber, an upper electrode provided above the piezoelectric element for applying a voltage to the piezoelectric element, a lower electrode provided below the piezoelectric element for applying a voltage to the piezoelectric element, a detection resistor provided below the piezoelectric element for detecting the temperature of the liquid in the pressure chamber, and a first wiring portion electrically connected to the detection resistor. The first wiring portion includes a first portion extending above the piezoelectric element and a second portion provided in at least a portion of a through hole penetrating the piezoelectric element and electrically connected to the detection resistor. According to this aspect of the liquid ejection head, by using the second portion to electrically connect the detection resistor to the first wiring portion, the wiring length of the detection resistor can be shortened compared to a structure in which the first wiring portion and the detection resistor are electrically connected by abutting them. This reduces energy loss and signal attenuation in the detection resistor, thereby improving the accuracy of temperature detection.

[0088] (2) The liquid ejection head of the above embodiment may further include a second wiring portion electrically connected to the lower electrode. The second wiring portion may be electrically connected to the lower electrode that is extended beyond the end of the piezoelectric body. According to this embodiment of the liquid ejection head, by extending the lower electrode beyond the end of the piezoelectric body, the contact area between the lower electrode and the piezoelectric body 70 can be increased, and the area of ​​the active part of the piezoelectric element can be increased.

[0089] (3) In the liquid ejection head of the above aspect, when viewed along the stacking direction of the piezoelectric body, the upper electrode, and the lower electrode, the area where the piezoelectric body and the first wiring portion overlap, in which the detection resistor is arranged, may be narrower than the area where the detection resistor is not arranged. According to the liquid ejection head of this aspect, the number of detection resistors near the connection portion between the first wiring portion and the detection resistors can be reduced, thereby suppressing energy loss and signal attenuation in the detection resistors and improving temperature detection accuracy.

[0090] (4) The liquid ejection head of the above aspect may further include a sealing substrate having a wall portion and a ceiling portion, the wall portion and the ceiling portion protecting an active portion of the piezoelectric element. When viewed along the stacking direction of the piezoelectric element, the upper electrode, and the lower electrode, the second portion may be provided at a position overlapping the ceiling portion. Covering the first portion with the sealing substrate protects the electrical connection between the first portion and the detection resistor, and can suppress problems such as electrical open circuits and short circuits between the first portion and the detection resistor.

[0091] (5) The liquid ejection head of the above aspect may further include a protective layer formed of the same material as the upper electrode between the second portion and the detection resistor. The second portion may be electrically connected to the detection resistor via at least a portion of the protective layer. According to this aspect of the liquid ejection head, by laminating a protective layer on the detection resistor exposed from the through-hole of the piezoelectric body, damage to the detection resistor due to etching or the like during the manufacturing process can be reduced or prevented. This can suppress variations in the film thickness of the detection resistor and suppress a decrease in temperature detection accuracy.

[0092] (6) In the liquid ejection head of the above aspect, the through hole may be covered with the protective layer having an area larger than that of the second portion when viewed along the stacking direction of the piezoelectric body, the upper electrode, and the lower electrode. According to this aspect of the liquid ejection head, by configuring the protective layer to cover the detection resistor exposed from the through hole, damage to the detection resistor due to etching or the like during the manufacturing process can be reduced or prevented.

[0093] (7) In the liquid ejection head of the above aspect, the second portion may be electrically connected to the detection resistor through an opening provided in the protective layer. According to this aspect of the liquid ejection head, while including the protective layer, the second portion can be brought into contact with the detection resistor through the opening, thereby reducing the electrical resistance between the detection resistor and the second portion and improving the accuracy of temperature detection.

[0094] (8) In the liquid ejection head of the above aspect, the upper electrode may be provided in common to the plurality of pressure chambers, and the lower electrode may be provided individually for the plurality of pressure chambers.

[0095] (9) In the liquid ejection head of the above aspect, the electrical resistance per unit length of the detection resistor may be higher than the electrical resistance per unit length of the first wiring portion. According to this aspect of the liquid ejection head, the temperature detection accuracy can be improved by increasing the electrical resistance of the detection resistor, and the temperature detection accuracy can be further improved by suppressing energy loss and signal attenuation in the first wiring portion.

[0096] (10) In the liquid ejection head of the above aspect, the second portion may be provided by filling the through hole. With this aspect, compared to the aspect including a protective layer, the liquid ejection head has a larger area where the second portion abuts against the detection resistor, thereby reducing the electrical resistance between the detection resistor and the second portion and improving the temperature detection accuracy.

[0097] (11) In the liquid ejection head of the above aspect, when the direction in which the plurality of pressure chambers are arranged is defined as an arrangement direction and the direction orthogonal to both the stacking direction and the stacking direction is defined as an intersecting direction, the detection resistor may include a first extension portion electrically connected to the first wiring portion and extending along the intersecting direction outside the plurality of pressure chambers, and a second extension portion continuous with the first extension portion and extending along the arrangement direction. According to the liquid ejection head of this aspect, by arranging the second extension portion along the arrangement direction of the plurality of pressure chambers, the detection resistor can be arranged efficiently from the viewpoint of temperature detection of the plurality of pressure chambers.

[0098] (12) In the liquid ejection head of the above aspect, when the shortest distance from the first extension portion to the plurality of pressure chambers is defined as a first distance and the shortest distance from the second extension portion to the plurality of pressure chambers is defined as a second distance, the first distance may be longer than the second distance. According to the liquid ejection head of this aspect, by arranging the second extension portion in the vicinity of the plurality of pressure chambers, it is possible to arrange the detection resistors more efficiently from the viewpoint of detecting the temperatures of the plurality of pressure chambers.

[0099] (13) According to another aspect of the present disclosure, there is provided a liquid ejection device including the liquid ejection head of the above aspect and a control unit that controls the ejection operation of the liquid ejection head.

[0100] The present disclosure can also be realized in various forms other than liquid ejection devices and liquid ejection heads, for example, in the form of a method for manufacturing a liquid ejection head, a method for manufacturing a liquid ejection device, etc.

[0101] The present disclosure is not limited to inkjet systems, but can also be applied to any liquid ejection device that ejects liquid other than ink and the liquid ejection heads used in such liquid ejection devices. For example, the present disclosure can be applied to various liquid ejection devices and their liquid ejection heads, such as those listed below. (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, surface-emitting displays (Field Emission Displays, FEDs), etc. (4) A liquid ejection device that ejects a liquid containing a bioorganic substance used in biochip manufacturing. (5) A sample dispensing 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 precisely onto precision machinery such as watches and cameras. (9) A liquid ejection device that ejects a transparent resin liquid, such as an ultraviolet curable 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.

[0102] A "liquid" can be any material that can be consumed by a liquid ejection device. For example, a "liquid" can be any material in a liquid phase, and includes materials with high or low viscosity, as well as liquid materials such as sols, gel water, other inorganic solvents, organic solvents, solutions, liquid resins, and liquid metals (metal melts). Furthermore, not only liquids as a state of matter, but also 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 main agent and hardener of adhesives. (2) Base paints and thinners, and clear paints and thinners. (3) A main solvent and a dilution solvent containing cells for the cell 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 ingredient and protective ingredient of a drug. (7) Phosphors and encapsulants for light-emitting diodes (LEDs). [Explanation of symbols]

[0103] 10...pressure chamber substrate, 12...pressure chamber, 13...throttle 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, 40...case member, 41...accommodation portion, 42...third manifold portion, 43...connection port, 44...supply port, 45 ...Compliance substrate, 46...sealing film, 47...fixed substrate, 48...opening, 49...compliance portion, 50...diaphragm, 55...elastic film, 56...insulating film, 60...first electrode, 60b...end, 70...piezoelectric body, 70H...through hole, 70a, 70b...end, 80...second electrode, 80b...end, 85...wiring portion, 91...individual lead electrode, 92...common lead electrode, 92a, 92b...extension portion, 93...measurement lead electrode, 93H, 93H2 , 93H3, 93H4...contact holes, 93a, 93b...wiring portion, 94, 94b...protective layer, 94T...opening, 96...wiring portion, 100...manifold, 120...relay substrate, 121...integrated circuit, 300...piezoelectric element, 400...temperature acquisition portion, 401...detection resistor, 401A...first extension portion, 401B...second extension portion, 401C...third extension portion, 402...low thermal conductivity layer, 430...current application circuit, 440...voltage detection circuit, 4 50...Temperature calculation unit, 460...Memory unit, 500...Liquid ejection device, 510...Liquid ejection head, 550...Ink tank, 552...Tube, 560...Transport mechanism, 562...Transport roller, 564...Transport rod, 566...Transport motor, 570...Moving mechanism, 572...Carriage, 574...Transport belt, 576...Moving motor, 577...Pulley, 580...Control unit, L1...First pressure chamber row, L2...Second pressure chamber row, P...Printing paper

Claims

1. A liquid ejection head, a pressure chamber substrate provided with a plurality of pressure chambers; a piezoelectric element that is driven to apply pressure to the liquid in the pressure chamber; an upper electrode provided on the upper part of the piezoelectric body for applying a voltage to the piezoelectric body; a lower electrode provided below the piezoelectric body for applying a voltage to the piezoelectric body; a detection resistor provided below the piezoelectric body for detecting the temperature of the liquid in the pressure chamber; a first wiring portion electrically connected to the detection resistor, the first wiring portion includes a first portion extending above the piezoelectric body, and a second portion provided in at least a part of a through hole penetrating the piezoelectric body and electrically connected to the detection resistor; Liquid ejection head.

2. 2. The liquid ejection head according to claim 1, a second wiring portion electrically connected to the lower electrode; the second wiring portion is electrically connected to the lower electrode that is drawn out beyond the end of the piezoelectric body; Liquid ejection head.

3. 3. The liquid ejection head according to claim 1, When viewed along a stacking direction of the piezoelectric body, the upper electrode, and the lower electrode, in a region where the piezoelectric body and the first wiring portion overlap, a range in which the detection resistor is arranged is narrower than a range in which the detection resistor is not arranged. Liquid ejection head.

4. 4. The liquid ejection head according to claim 1, a sealing substrate having a wall portion and a ceiling portion, the wall portion and the ceiling portion protecting an active portion of the piezoelectric element; the second portion is provided at a position overlapping the ceiling portion when viewed along a stacking direction of the piezoelectric body, the upper electrode, and the lower electrode. Liquid ejection head.

5. 5. The liquid ejection head according to claim 1, a protection layer formed of the same material as the upper electrode between the second portion and the detection resistor; the second portion is electrically connected to the sense resistor through at least a part of the protection layer. Liquid ejection head.

6. 6. The liquid ejection head according to claim 5, the through hole is covered with the protective layer having an area larger than an area of ​​the second portion when viewed along a stacking direction of the piezoelectric body, the upper electrode, and the lower electrode; Liquid ejection head.

7. 7. The liquid ejection head according to claim 5, the second portion is electrically connected to the detection resistor through an opening provided in the protective layer. Liquid ejection head.

8. 8. The liquid ejection head according to claim 1, the upper electrode is provided in common to the plurality of pressure chambers, the lower electrodes are provided individually for the plurality of pressure chambers; Liquid ejection head.

9. 9. The liquid ejection head according to claim 1, wherein the electrical resistance value per unit length of the detection resistor is higher than the electrical resistance value per unit length of the first wiring portion.

10. The liquid ejection head according to claim 1 , wherein the second portion is provided by filling the through-hole.

11. 11. The liquid ejection head according to claim 1, a direction in which the plurality of pressure chambers are arranged is defined as an arrangement direction; When a direction perpendicular to both the stacking direction of the piezoelectric body, the upper electrode, and the lower electrode and the arrangement direction is defined as an intersecting direction, The detection resistor is a first extending portion electrically connected to the first wiring portion and extending along the intersecting direction outside the plurality of pressure chambers; a second extension portion that is continuous with the first extension portion and extends along the arrangement direction, Liquid ejection head.

12. The liquid ejection head according to claim 11, When the shortest distance from the first extension portion to the plurality of pressure chambers is defined as a first distance, and the shortest distance from the second extension portion to the plurality of pressure chambers is defined as a second distance, The first distance is greater than the second distance. Liquid ejection head.

13. A liquid ejection head according to any one of claims 1 to 12; a control unit that controls the ejection operation of the liquid ejection head, Liquid discharge device.

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