Liquid ejection head unit and liquid ejection device

Abstract

To provide a technique that reduces the influence of heat and noise from surrounding circuits on a temperature detection circuit, and improves the accuracy of temperature detection performed by the temperature detection circuit in a liquid discharge head unit.SOLUTION: A liquid discharge head unit comprises: a pressure chamber substrate having a plurality of pressure chambers; a piezoelectric element which applies a pressure to the plurality of pressure chambers; a liquid discharge head on which a drive wiring is provided which applies a voltage for driving the piezoelectric element to the piezoelectric element; and a wiring board. On the liquid discharge head, a detection resistor, which is formed from the same material as that of the piezoelectric element or the drive wiring and detects the temperature of the pressure chamber, is provided. The wiring board is provided with a first circuit, a second circuit, and a temperature detection circuit electrically connected to the detection resistor. The distance between the first circuit and the second circuit becomes a first distance, the distance between the first circuit and the temperature detection circuit becomes a second distance longer than the first distance, and the distance between the second circuit and the temperature detection circuit becomes a third distance longer than the first distance.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present disclosure relates to a liquid ejection head unit and a liquid ejection device.

Background Art

[0002] A printer is described that changes the number of application times of a maintenance drive pulse applied to a piezoelectric element based on the ambient temperature detected by a temperature sensor provided on the side surface of a carriage on which a liquid ejection head is mounted.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a liquid ejection head including a piezoelectric element, if a temperature detection circuit is provided outside the liquid ejection head, there is a possibility that the temperature of the ink in the pressure chamber cannot be accurately detected. Therefore, there is a desire to dispose the temperature detection circuit inside the liquid ejection head. However, if the temperature detection circuit is simply disposed on the wiring board inside the liquid ejection head, the measurement accuracy of the temperature by the temperature detection circuit may decrease.

Means for Solving the Problems

[0005] The present disclosure can be realized in the following forms.

[0006] According to a first aspect of the present disclosure, a liquid ejection head unit is provided. The liquid ejection head unit includes a pressure chamber substrate having a plurality of pressure chambers, a piezoelectric element laminated on the pressure chamber substrate for applying pressure to each of the plurality of pressure chambers, and a liquid ejection head provided with drive wiring for applying a voltage for driving the piezoelectric element to the piezoelectric element, and a wiring substrate electrically connected to the liquid ejection head. A detection resistor formed of the same material as the piezoelectric element or the drive wiring is provided in the liquid ejection head for detecting the temperature of the pressure chamber. The wiring substrate is provided with a first circuit, a second circuit different from the first circuit, and a temperature detection circuit electrically connected to the detection resistor. The first circuit, the second circuit, and the temperature detection circuit are provided on the wiring substrate such that a distance between the first circuit and the second circuit is a first distance, a distance between the first circuit and the temperature detection circuit is a second distance longer than the first distance, and a distance between the second circuit and the temperature detection circuit is a third distance longer than the first distance.

[0007] According to a second aspect of the present disclosure, a liquid ejection device is provided. The liquid ejection device includes the liquid ejection head unit according to the first aspect, and a liquid storage unit for storing the liquid ejected from the liquid ejection head unit.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Mode for Carrying Out the Invention

[0009] A. First Embodiment: FIG. 1 is an explanatory diagram showing a schematic configuration of a liquid ejection device 500 as a first embodiment of the present disclosure. In the present embodiment, the liquid ejection device 500 is an inkjet printer that ejects ink, which is an example of a liquid, onto a printing paper P to form an image. Instead of the printing paper P, the liquid ejection device 500 may use any type of medium such as a resin film or a fabric as the ejection target of the ink. X, Y, and Z shown in FIG. 1 and each subsequent figure represent three mutually orthogonal spatial axes. 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 a direction, the positive direction is denoted as "+", the negative direction is denoted as "-", and positive and negative signs are used in combination in the direction notation. The direction in which the arrow in each figure points is the + direction, and the opposite direction is the - direction for explanation. In the present embodiment, the Z direction coincides with the vertical direction, the +Z direction indicates vertically downward, and the -Z direction indicates vertically upward. Further, when the positive and negative directions are not limited, the three X, Y, and Z are described as the X-axis, the Y-axis, and the Z-axis.

[0010] As shown in FIG. 1, the liquid ejection device 500 includes a print head 5, an ink tank 550, a conveyance mechanism 560, a moving mechanism 570, and a control unit 540. A signal for controlling ink ejection and the like is supplied from the control unit 540 to the print head 5 via a cable 590. The print head 5 ejects the ink supplied from the ink tank 550 in an amount and at a timing according to the signal supplied from the control unit 540. The print head 5 includes the liquid ejection head unit 51 of the present embodiment and a circuit board described later. Although not shown in FIG. 1, in the present embodiment, the print head 5 includes a plurality of liquid ejection head units 51. Each liquid ejection head unit 51 is provided with a plurality of liquid ejection heads 510. The liquid ejection head unit 51 and the liquid ejection head 510 are not limited to plural numbers and may be singular numbers respectively.

[0011] The liquid ejection head 510 ejects, for example, a total of four colors of ink, namely black, cyan, magenta, and yellow, from the nozzles in the +Z direction to form an image on the printing paper P. The liquid ejection head 510 reciprocates in the main scanning direction along with the movement of the carriage 572. In the present embodiment, the main scanning direction is the +X direction and the -X direction. The liquid ejection head 510 may eject ink of any color, not limited to four colors, such as light cyan, light magenta, and white. The liquid ejection head 510 has a detection resistor 401 and a heating resistor 601.

[0012] The ink tank 550 functions as a liquid storage unit for storing ink. The ink tank 550 is connected to the print head 5 by a resin tube 552, and the ink in the ink tank 550 is supplied to the print head 5 via the tube 552. The ink supplied to the print head 5 is supplied to each liquid ejection head 510. Instead of the ink tank 550, a bag-shaped liquid pack formed of a flexible film may be provided.

[0013] The conveyance mechanism 560 conveys the printing paper P in the sub-scanning direction. The sub-scanning direction is a direction intersecting the X-axis direction which is the main scanning direction, and in this embodiment, it is the +Y direction and the -Y direction. The conveyance mechanism 560 includes a conveyance rod 564 to which three conveyance rollers 562 are attached, and a conveyance motor 566 that rotationally drives the conveyance rod 564. When the conveyance motor 566 rotationally drives the conveyance rod 564, the printing paper P is conveyed in the +Y direction which is the sub-scanning direction. The number of the conveyance rollers 562 is not limited to three and may be any number. Also, a configuration in which a plurality of conveyance mechanisms 560 are provided may be adopted.

[0014] The movement mechanism 570 includes a carriage 572, a conveyance belt 574, a movement motor 576, and a pulley 577. The carriage 572 mounts the print head 5 in a state where ink can be ejected. The carriage 572 is fixed to the conveyance belt 574. The conveyance belt 574 is spanned between the movement motor 576 and the pulley 577. When the movement motor 576 rotationally drives, the conveyance belt 574 reciprocates in the main scanning direction. Thereby, the carriage 572 fixed to the conveyance belt 574 also reciprocates in the main scanning direction.

[0015] The control unit 540 controls the entire liquid ejection device 500. The control unit 540 controls, for example, the reciprocating motion along the main scanning direction of the carriage 572, the conveyance motion along the sub-scanning direction of the printing paper P, the ejection operation of the liquid ejection head 510, and the like. The control unit 540 also functions as a drive control unit for the piezoelectric element 300. In the present embodiment, the control unit 540 can further heat the liquid in the pressure chamber 12 by the heating resistor 601 provided in the liquid ejection head 510, and can detect the temperature of the pressure chamber 12 by the detection resistor 401 provided in the liquid ejection head 510. The control unit 540 detects the temperature of the pressure chamber 12 and adjusts the temperature of the pressure chamber 12 by heating. The control unit 540 outputs a drive signal based on the detected temperature of the pressure chamber 12 to the liquid ejection head 510 and drives the piezoelectric element 300 to control the ejection of ink onto the printing paper P. The control unit 540 may be composed of, 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. In the present embodiment, the control unit 540 stores in advance in the storage circuit the correspondence relationship between the electrical resistance value of the detection resistor 401 and the temperature.

[0016] The detailed configuration of the liquid ejection head 510 will be described with reference to FIGS. 2 to 4. FIG. 2 is an exploded perspective view showing the configuration of the liquid ejection head 510. FIG. 3 is an explanatory view showing the configuration of the liquid ejection head 510 in a plan view. In FIG. 3, the configuration around the pressure chamber substrate 10 in the liquid ejection head 510 is shown. In FIG. 3, for ease of understanding of the technology, the protective substrate 30 and the case member 40 are omitted. FIG. 4 is a cross-sectional view showing the position IV-IV of FIG. 3.

[0017] As shown in FIG. 2, the liquid ejection head 510 includes a pressure chamber substrate 10, a communication plate 15, a nozzle plate 20, a compliance substrate 45, a protection substrate 30, a case member 40, and an intermediate substrate 120. Further, as shown in FIG. 3, it includes a piezoelectric element 300 and, as shown in FIG. 4, a diaphragm 50. The pressure chamber substrate 10, the communication plate 15, the nozzle plate 20, the compliance substrate 45, the diaphragm 50, the piezoelectric element 300, the protection substrate 30, and the case member 40 are laminated members, and by laminating them, the liquid ejection head 510 is formed. In the present disclosure, the direction in which the laminated members forming the liquid ejection head 510 are laminated is also referred to as the "lamination direction".

[0018] The pressure chamber substrate 10 is formed using, for example, a silicon substrate, a glass substrate, an SOI substrate, various ceramic substrates, or the like. As shown in FIG. 3, a plurality of pressure chambers 12 are arranged on the pressure chamber substrate 10 along a direction predetermined in the pressure chamber substrate 10. The direction in which the plurality of pressure chambers 12 are arranged is also referred to as the "arrangement direction". The pressure chamber 12 is formed in a rectangular shape in which the length in the X-axis direction is longer than the length in the Y-axis direction in plan view. The shape of the pressure chamber 12 is not limited to a rectangular shape, and may be a parallelogram shape, a polygonal shape, a circular shape, an oval shape, or the like. The oval shape referred to here means a shape in which both ends in the longitudinal direction are semi-circular based on a rectangular shape, and includes a rounded rectangular shape, an elliptical shape, an egg shape, and the like.

[0019] In the present embodiment, the plurality of pressure chambers 12 are arranged in two columns with the Y-axis direction as the arrangement direction. In the example of FIG. 3, on the pressure chamber substrate 10, two pressure chamber columns are formed: a first pressure chamber column L1 with the Y-axis direction as the arrangement direction and a second pressure chamber column L2 with the Y-axis direction as the arrangement direction. The second pressure chamber column L2 is arranged adjacent to the first pressure chamber column L1 in a direction intersecting the arrangement direction of the first pressure chamber column L1. The direction intersecting the arrangement direction is also referred to as the "intersecting direction". In the example of FIG. 3, the intersecting direction is the X-axis direction, and the second pressure chamber column L2 is adjacent to the first pressure chamber column L1 in the -X direction. The arrangement direction means the macroscopic arrangement direction of the plurality of pressure chambers 12. For example, it also includes the case where a plurality of pressure chambers 12 are arranged along the Y-axis direction according to a so-called staggered arrangement, where they are alternately arranged in the intersecting direction at every other one.

[0020] The plurality of pressure chambers 12 belonging to the first pressure chamber column L1 and the plurality of pressure chambers 12 belonging to the second pressure chamber column L2 are formed such that their positions in the arrangement direction coincide with each other, and are arranged adjacent to each other in the intersecting direction. In each pressure chamber column, the pressure chambers 12 adjacent to each other in the Y-axis direction are partitioned by a partition wall 11 shown in FIG. 6, as will be described later.

[0021] As shown in FIG. 2, on the +Z direction side of the pressure chamber substrate 10, a communication plate 15, a nozzle plate 20, and a compliance substrate 45 are laminated in this order. The communication plate 15 is, for example, a flat member made of a silicon substrate, a glass substrate, an SOI substrate, various ceramic substrates, a metal substrate, or the like. Examples of the metal substrate include a stainless steel substrate. As shown in FIG. 4, the communication plate 15 is provided with a nozzle communication path 16, a first manifold portion 17, a second manifold portion 18, and a supply communication path 19. It is preferable to use a material for the communication plate 15 having a coefficient of thermal expansion substantially the same as that of the pressure chamber substrate 10. Thereby, when the temperatures of the pressure chamber substrate 10 and the communication plate 15 change, warping of the pressure chamber substrate 10 and the communication plate 15 due to the difference in the coefficient of thermal expansion can be suppressed.

[0022] As shown in FIG. 4, the nozzle communication passage 16 is a passage that communicates the pressure chamber 12 and the nozzle 21. The first manifold portion 17 and the second manifold portion 18 function as a part of the manifold 100 that serves as a common liquid chamber in which a plurality of pressure chambers 12 communicate. The first manifold portion 17 is provided so as to penetrate the communication plate 15 in the Z-axis direction. Further, as shown in FIG. 4, 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.

[0023] The supply communication passage 19 is a passage that communicates with one end of the pressure chamber 12 in the X-axis direction. There are a plurality of supply communication passages 19, which are arranged along the Y-axis direction, that is, the arrangement direction, and are individually provided for each of the pressure chambers 12. The supply communication passage 19 communicates the second manifold portion 18 and each pressure chamber 12 to supply the ink in the manifold 100 to each pressure chamber 12.

[0024] The nozzle plate 20 is provided on the side opposite to the pressure chamber substrate 10 with the communication plate 15 interposed therebetween, that is, on the surface of the communication plate 15 on the +Z direction side. The material of the nozzle plate 20 is not particularly limited, and for example, a silicon substrate, a glass substrate, an SOI substrate, various ceramic substrates, or a metal substrate can be used. Examples of the metal substrate include a stainless substrate. As the material of the nozzle plate 20, an organic substance such as a polyimide resin can also be used. However, it is preferable to use a material having substantially the same coefficient of thermal expansion as that of the communication plate 15 for the nozzle plate 20. Thereby, when the temperatures of the nozzle plate 20 and the communication plate 15 change, warping of the nozzle plate 20 and the communication plate 15 due to the difference in the coefficient of thermal expansion can be suppressed.

[0025] A plurality of nozzles 21 are formed in the nozzle plate 20. Each nozzle 21 communicates with each pressure chamber 12 via the nozzle communication passage 16. The plurality of nozzles 21 are arranged along the arrangement direction of the pressure chambers 12, that is, the Y-axis direction. Two nozzle rows in which these plurality of nozzles 21 are arranged in a row are provided in the nozzle plate 20. The two nozzle rows respectively correspond to the first pressure chamber row L1 and the second pressure chamber row L2.

[0026] As shown in FIG. 4, the compliance substrate 45 is provided on the surface on the opposite side of the pressure chamber substrate 10 across the communication plate 15 together with the nozzle plate 20, that is, on the +Z direction side surface of the communication plate 15. 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 on the communication plate 15. In the present 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. 4, the region of the fixed substrate 47 facing the manifold 100 is an opening 48 that is completely removed in the thickness direction. For this reason, one surface of the manifold 100 is a compliance portion 49 sealed only by the sealing film 46.

[0027] As shown in FIG. 4, on the surface on the opposite side of the nozzle plate 20 etc. across the pressure chamber substrate 10, that is, on the -Z direction side surface of the pressure chamber substrate 10, a diaphragm 50 and a piezoelectric element 300 are laminated. The piezoelectric element 300 causes the diaphragm 50 to flex and deform, generating a pressure change in the ink in the pressure chamber 12. In FIG. 4, for ease of understanding of the technology, the configuration of the piezoelectric element 300 is shown in a simplified manner. The diaphragm 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 diaphragm 50.

[0028]

[0029] ​As shown in Fig. 4, a case member 40 is fixed on a protection substrate 30. The case member 40 forms a manifold 100 communicating with a plurality of pressure chambers 12 together with a communication plate 15. The case member 40 has an outer shape substantially the same as that of the communication plate 15 in a plan view, and is joined across the protection substrate 30 and the communication plate 15.

[0030] The case member 40 has a housing portion 41, a supply port 44, a third manifold portion 42, and a connection port 43. The housing portion 41 is a space having a depth capable of housing the pressure chamber substrate 10 and the protection substrate 30. The third manifold portion 42 is a space formed on both outer sides in the X-axis direction of the housing portion 41 in the case member 40. The manifold 100 is formed by connecting the third manifold portion 42 to a first manifold portion 17 and a second manifold portion 18 provided on the communication plate 15. The manifold 100 has an elongated shape continuous in the Y-axis direction. The supply port 44 communicates with the manifold 100 to supply ink to each manifold 100. The connection port 43 is a through hole communicating with the through hole 32 of the protection substrate 30, and the relay substrate 120 is inserted therethrough.

[0031] As shown in Fig. 4, in the liquid ejection head 510 of the present embodiment, the ink supplied from the ink tank 550 shown in Fig. 1 is taken in from the supply port 44, and after filling the internal flow path with ink from the manifold 100 to the nozzles 21, a voltage based on a drive signal is applied to each piezoelectric element 300 corresponding to the plurality of pressure chambers 12. Thereby, the diaphragm 50 bends and deforms together with the piezoelectric element 300, the pressure in each pressure chamber 12 increases, and ink droplets are ejected from each nozzle 21.

[0032] The structure on the -Z direction side of the pressure chamber substrate 10 will be described with reference to FIGS. 3 to 6. FIG. 5 is a cross-sectional view showing an enlarged view of the vicinity of the piezoelectric element 300. FIG. 6 is a cross-sectional view showing the position VI-VI in FIG. 3. The liquid ejection head 510 has, on the -Z direction side of the pressure chamber substrate 10, in addition to the diaphragm 50 and the piezoelectric element 300, an individual lead electrode 91, a common lead electrode 92, a measurement lead electrode 93, a heating lead electrode 94, a detection resistor 401, and a heating resistor 601.

[0033] As shown in FIGS. 5 and 6, the diaphragm 50 includes an elastic film 55 made of silicon oxide provided on the pressure chamber substrate 10 side, and an insulator film 56 made of a zirconium oxide film provided on the elastic film 55. The flow path formed in the pressure chamber substrate 10 such as the pressure chamber 12 is formed by anisotropic etching of the pressure chamber substrate 10 from the +Z direction side surface, and the -Z direction side surface of the flow path such as the pressure chamber 12 is constituted by the elastic film 55. The diaphragm 50 may be constituted by, for example, either one of the elastic film 55 and the insulator film 56, and furthermore, other films other than the elastic film 55 and the insulator film 56 may be included. Examples of the material of the other film include silicon and silicon nitride.

[0034] The piezoelectric element 300 applies pressure to the pressure chamber 12. As shown in FIGS. 5 and 6, the piezoelectric element 300 has a first electrode 60, a piezoelectric body 70, and a second electrode 80. The first electrode 60, the piezoelectric body 70, and the second electrode 80 are laminated in order from the +Z direction side to the -Z direction side as shown in FIGS. 5 and 6. The piezoelectric body 70 is provided between the first electrode 60 and the second electrode 80 in the lamination direction in which the first electrode 60, the second electrode 80, and the piezoelectric body 70 are laminated, that is, the Z-axis direction.

[0035] Both the first electrode 60 and the second electrode 80 are electrically connected to the relay substrate 120. The first electrode 60 and the second electrode 80 apply a voltage corresponding to a drive signal to the piezoelectric body 70. Different drive voltages are supplied to the first electrode 60 according to the ink ejection amount, and a constant reference voltage signal is supplied to the second electrode 80 regardless of the ink ejection amount. The ink ejection amount is the required volume change amount in the pressure chamber 12. When a potential difference occurs between the first electrode 60 and the second electrode 80 due to the driving of the piezoelectric element 300, the piezoelectric body 70 deforms. Due to the deformation of the piezoelectric body 70, the diaphragm 50 deforms or vibrates, and the volume of the pressure chamber 12 changes. When the volume of the pressure chamber 12 changes, pressure is applied to the ink accommodated in the pressure chamber 12, and the ink is ejected from the nozzle 21 through the nozzle communication passage 16.

[0036] As shown in FIG. 5, 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 310. On the other hand, a portion where no piezoelectric strain occurs in the piezoelectric body 70 is also called an inactive portion 320. That is, among the piezoelectric element 300, the portion where the piezoelectric body 70 is sandwiched between the first electrode 60 and the second electrode 80 is the active portion 310, and the portion where the piezoelectric body 70 is not sandwiched between the first electrode 60 and the second electrode 80 is the inactive portion 320. When the piezoelectric element 300 is driven, a portion that actually displaces in the Z-axis direction is also called a flexible portion, and a portion that does not displace in the Z direction is also called a non-flexible portion. That is, among the piezoelectric element 300, the portion facing the pressure chamber 12 in the Z-axis direction becomes the flexible portion, and the outer portion of the pressure chamber 12 becomes the non-flexible portion. The active portion 310 is also called an active part, and the inactive portion 320 is also called a non-active part.

[0037] The first electrode 60 is formed of a conductive material such as a metal such as platinum (Pt), iridium (Ir), gold (Au), titanium (Ti), or a conductive metal oxide such as indium tin oxide abbreviated as ITO. The first electrode 60 may be formed by laminating a plurality of materials such as platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti). In the present embodiment, platinum (Pt) is used as the first electrode 60.

[0038] As shown in FIG. 3, the first electrode 60 is an individual electrode provided individually for a plurality of pressure chambers 12. The width of the first electrode 60 in the Y-axis direction is narrower than the width of the pressure chamber 12. That is, both ends of the first electrode 60 in the Y direction are located inside both ends of the pressure chamber 12 in the Y-axis direction. As shown in FIG. 5, the +X-direction end portion 60a and the -X-direction end portion 60b of the first electrode 60 are respectively arranged outside the pressure chamber 12. For example, in the first pressure chamber row, the end portion 60a of the first electrode 60 is arranged at a position on the +X-direction side with respect to the +X-direction end portion 12a of the pressure chamber 12. The end portion 60b of the first electrode 60 is arranged at a position on the -X-direction side with respect to the -X-direction end portion 12b of the pressure chamber 12.

[0039] As shown in FIG. 3, the piezoelectric body 70 has a predetermined width in the X-axis direction and extends along the arrangement direction of the pressure chambers 12, that is, the Y-axis direction. Examples of the piezoelectric body 70 include a perovskite-structured crystal film made of a ferroelectric ceramic material exhibiting an electromechanical conversion effect formed on the first electrode 60, a so-called perovskite-type crystal. As the material of the piezoelectric body 70, for example, a ferroelectric piezoelectric material such as lead zirconate titanate (PZT), or a material obtained by adding a metal oxide such as niobium oxide, nickel oxide, or magnesium oxide thereto can be used. 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), or lead zirconium titanate magnesium niobate (Pb(Zr,Ti)(Mg,Nb)O3) can be used. In the present embodiment, lead zirconate titanate (PZT) is used as the piezoelectric body 70.

[0040] The material of the piezoelectric body 70 is not limited to lead-based piezoelectric materials containing lead, and non-lead-based piezoelectric materials can also be used. Examples of non-lead-based 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 tantalum 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"), bismuth manganate (BiMnO3, abbreviated as "BM"), a composite oxide containing bismuth, potassium, titanium and iron and having a perovskite structure (x[(BixK1-x)TiO3]-(1-x)[BiFeO3], abbreviated as "BKT-BF"), a composite oxide containing bismuth, iron, barium and titanium and having a perovskite structure ((1-x)[BiFeO3]-x[BaTiO3], abbreviated as "BFO-BT"), and those obtained by adding metals such as manganese, cobalt and chromium thereto ((1-x)[Bi(Fe1-yMy)O3]-x[BaTiO3] (M is Mn, Co or Cr)), etc.

[0041] The thickness of the piezoelectric body 70 is formed to be about 1000 nanometers to 4000 nanometers, for example. As shown in FIG. 5, the width of the piezoelectric body 70 in the X-axis direction is longer than the length in the X-axis direction, which is the longitudinal direction of the pressure chamber 12. Therefore, on both sides of the pressure chamber 12 in the X-axis direction, the piezoelectric body 70 extends to the outside of the pressure chamber 12. In this way, since the piezoelectric body 70 extends to the outside of the pressure chamber 12 in the X-axis direction, the strength of the diaphragm 50 is improved. Therefore, when the active part 310 is driven to displace the piezoelectric element 300, it is possible to suppress the occurrence of cracks or the like in the diaphragm 50 and the piezoelectric element 300.

[0042] As shown in Fig. 5, the +X-direction end 70a of the piezoelectric body 70 is located on the +X-direction side outside the end 60a of the first electrode 60 in the first pressure chamber row. That is, the end 60a of the first electrode 60 is covered by the piezoelectric body 70. On the other hand, the -X-direction end 70b of the piezoelectric body 70 is located on the +X-direction side inside the end 60b of the first electrode 60, and the end 60b of the first electrode 60 is not covered by the piezoelectric body 70.

[0043] As shown in Figs. 3 and 6, the piezoelectric body 70 is formed with a groove portion 71 which is a portion thinner in thickness than other regions. As shown in Fig. 6, the groove portion 71 is provided at a position corresponding to each partition wall 11. The groove portion 71 is formed by completely removing the piezoelectric body 70 in the Z-axis direction. The piezoelectric body 70 may be formed thinner than other portions on the bottom surface of the groove portion 71. The width of the groove portion 71 in the Y-axis direction is the same as or wider than the width of the partition wall 11 in the Y-axis direction. As shown in Fig. 3, the groove portion 71 has a substantially rectangular appearance shape in plan view. By providing the groove portion 71 in the piezoelectric body 70, the rigidity of the portion facing the Y-axis direction end of the pressure chamber 12 of the diaphragm 50, that is, the so-called arm portion of the diaphragm 50, can be suppressed, so that the piezoelectric element 300 can be displaced better. The groove portion 71 is not limited to a rectangular shape, and may be a polygon with five or more sides, or may be a circular shape, an elliptical shape, etc.

[0044] As shown in Figs. 5 and 6, the second electrode 80 is provided on the opposite side of the first electrode 60 with the piezoelectric body 70 interposed therebetween, that is, on the -Z-direction side of the piezoelectric body 70. As shown in Fig. 3, the second electrode 80 is provided in common for a plurality of pressure chambers 12 and is a common electrode common to a plurality of active portions 310. The material of the second electrode 80 is not particularly limited, but similar to the first electrode 60, for example, conductive materials such as metals such as platinum (Pt), iridium (Ir), gold (Au), titanium (Ti), and indium tin oxide abbreviated as ITO are used. Alternatively, a plurality of materials such as platinum (Pt), iridium (Ir), gold (Au), titanium (Ti), etc. may be laminated and formed. In this embodiment, iridium (Ir) is used as the second electrode 80.

[0045] As shown in FIG. 3, the second electrode 80 has a predetermined width in the X-axis direction and extends along the arrangement direction of the pressure chambers 12, that is, in the Y-axis direction. As shown in FIG. 6, the second electrode 80 is also provided on the side surface of the groove portion 71 of the piezoelectric body 70 and on the insulator film 56 which is the bottom surface of the groove portion 71.

[0046] As shown in FIG. 5, the end portion 80a of the second electrode 80 in the +X direction is disposed outside, that is, on the +X direction side, of the end portion 60a of the first electrode 60 covered by the piezoelectric body 70. The end portion 80a of the second electrode 80 is outside the end portion 12a of the pressure chamber 12 and is located outside the end portion 60a of the first electrode 60. In the present embodiment, the end portion 80a of the second electrode 80 substantially coincides with the end portion 70a of the piezoelectric body 70 in the X-axis direction. As a result, at the end portion of the active portion 310 in the +X direction, the boundary between the active portion 310 and the inactive portion 320 is defined by the end portion 60a of the first electrode 60.

[0047] As shown in FIG. 5, the end portion 80b of the second electrode 80 in the -X direction is disposed on the -X direction side outside the end portion 12b of the pressure chamber 12 in the -X direction and is disposed on the +X direction side inside the end portion 70b of the piezoelectric body 70. The end portion 70b of the piezoelectric body 70 is located on the inner side on the +X direction side of the end portion 60b of the first electrode 60. Therefore, the end portion 80b of the second electrode 80 is located on the piezoelectric body 70 on the +X direction side of the end portion 60b of the first electrode 60. On the -X direction side of the end portion 80b of the second electrode 80, there is a portion where the surface of the piezoelectric body 70 is exposed. Thus, since the end portion 80b of the second electrode 80 is disposed on the +X direction side of the end portion 70b of the piezoelectric body 70 and the end portion 60b of the first electrode 60, at the end portion of the active portion 310 in the -X direction, the boundary between the active portion 310 and the inactive portion 320 is defined by the end portion 80b of the second electrode 80.

[0048] Outside the end 80b of the second electrode 80, a wiring portion 85 is provided which is in the same layer as the second electrode 80 but is electrically discontinuous from the second electrode 80. The wiring portion 85 is formed from the vicinity of the end 70b of the piezoelectric body 70 to the end 60b of the first electrode 60 with a space from the end 80b of the second electrode 80. The wiring portion 85 is provided for each active portion 310. That is, a plurality of wiring portions 85 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. Thereby, the manufacturing process of the wiring portion 85 can be simplified and the cost can be reduced. However, the wiring portion 85 may be formed in a layer different from the second electrode 80.

[0049] As shown in FIG. 5, an individual lead electrode 91 is electrically connected to the first electrode 60 which is an individual electrode, and a common lead electrode 92 which is a driving common electrode is 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 driving wirings for applying a voltage for driving the piezoelectric body 70 to the piezoelectric body 70. In the present embodiment, the power supply circuit for supplying power to the piezoelectric body 70 via the driving wiring and the power supply circuit for supplying power to the heating resistor 601 and the detection resistor 401 are different circuits from each other.

[0050] As shown in FIGS. 3 and 4, the individual lead electrode 91 and the common lead electrode 92 extend so as to be exposed in the through hole 32 formed in the protective substrate 30, and are electrically connected to the relay substrate 120 in the through hole 32. A plurality of wirings for connecting to the control substrate 580 and a power supply circuit (not shown) are formed on the relay substrate 120. In the present embodiment, the relay substrate 120 is constituted by, for example, a flexible printed circuit (FPC). Instead of the FPC, it may be constituted by any substrate having flexibility such as a flexible flat cable (FFC).

[0051] An integrated circuit 121 having a switching element is mounted on the relay substrate 120. A signal for driving the piezoelectric element 300 propagating on the relay substrate 120 is input to the integrated circuit 121. The integrated circuit 121 controls the timing at which a signal for driving the piezoelectric element 300 is supplied to the first electrode 60 based on the input signal. Thereby, the timing at which the piezoelectric element 300 is driven and the driving amount of the piezoelectric element 300 are controlled.

[0052] The materials of the individual lead electrodes 91 and the common lead electrode 92 are conductive materials. For example, gold (Au), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), platinum (Pt), aluminum (Al), etc. can be used. In the present embodiment, gold (Au) is used as the individual lead electrodes 91 and the common lead electrode 92. Further, the individual lead electrodes 91 and the common lead electrode 92 may have an adhesion layer that improves the adhesion to the first electrode 60, the second electrode 80, and the diaphragm 50.

[0053] The individual lead electrodes 91 and the common lead electrode 92 are formed in the same layer but are formed so as to be electrically discontinuous. Thereby, compared with the case where the individual lead electrodes 91 and the common lead electrode 92 are formed individually, the manufacturing process can be simplified and the cost can be reduced. The individual lead electrodes 91 and the common lead electrode 92 may be formed in different layers.

[0054] The individual lead electrodes 91 are provided for each active part 310, that is, for each first electrode 60. As shown in FIG. 5, for example, in the first pressure chamber row L1, the individual lead electrodes 91 are connected to the vicinity of the end 60b of the first electrode 60 via the wiring part 85 and are drawn out in the -X direction up to the diaphragm 50.

[0055] As shown in FIG. 3, for example, in the first pressure chamber row L1, the common lead electrode 92 is drawn in the -X direction from above the second electrode 80 to above the diaphragm 50 at both ends in the Y-axis direction. The common lead electrode 92 has an extended portion 92a and an extended portion 92b. As shown in FIG. 5, for example, in the first pressure chamber row, the extended portion 92a extends along the Y-axis direction in a region corresponding to the end portion 12a of the pressure chamber 12, and the extended portion 92b extends along the Y-axis direction in a region corresponding to the end portion 12b of the pressure chamber 12. The extended portion 92a and the extended portion 92b are continuously provided across a plurality of active portions 310 in the Y-axis direction.

[0056] The extended portion 92a and the extended portion 92b extend from the inside of the pressure chamber 12 to the outside of the pressure chamber 12 in the X-axis direction. In the present embodiment, the active portion 310 of the piezoelectric element 300 extends to the outside of the pressure chamber 12 at both ends in the X-axis direction of the pressure chamber 12, and the extended portion 92a and the extended portion 92b extend to the outside of the pressure chamber 12 on the active portion 310.

[0057] As shown in FIGS. 3 and 5, a heating resistor 601 is provided on the -Z direction side surface of the diaphragm 50, specifically, on the -Z direction side surface of the diaphragm 50. Specifically, the heating resistor 601 is located between the diaphragm 50 and the piezoelectric body 70 in the Z-axis direction and is covered by the piezoelectric body 70. The heating resistor 601 is a conductor wiring used to heat the inside of the pressure chamber 12. In the present embodiment, the heating resistor 601 heats the liquid inside the pressure chamber 12 by utilizing resistive heating generated by passing an electric current through the electrical resistance of a metal, semiconductor, or the like.

[0058] As the material of the heating resistor 601, various heating elements can be used. As the heating element, for example, metal heating elements such as gold (Au), platinum (Pt), iridium (Ir), aluminum (Al), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), etc. can be used. The heating resistor 601 may be formed of a non-metal heating element such as silicon carbide, molybdenum silicide, carbon, etc. In the present embodiment, the heating resistor 601 is arranged at the same position as the first electrode 60 in the stacking direction, that is, in the same layer as the first electrode 60, and is formed so as to be electrically discontinuous with the first electrode 60. The material of the heating resistor 601 is the same platinum (Pt) as the first electrode 60. Thereby, compared with the case where the heating resistor 601 is formed separately from the first electrode 60, the manufacturing process can be simplified and the cost can be reduced. The heating resistor 601 may be formed in a layer different from the first electrode 60.

[0059] As shown in FIG. 3, a part of the heating resistor 601 is linearly formed along the first pressure chamber row L1, and is arranged on the +X direction side with respect to the pressure chamber 12 included in the first pressure chamber row L1, that is, outside the liquid ejection head 510 in the intersecting direction. In the present embodiment, in other parts of the heating resistor 601, it is linearly formed along the second pressure chamber row L2, and is arranged on the -X direction side with respect to the pressure chamber 12 included in the second pressure chamber row L2, that is, outside the liquid ejection head 510 in the intersecting direction. Thus, in the present embodiment, the heating resistor 601 is continuously formed outside the liquid ejection head 510 so as to surround the first pressure chamber row L1 and the second pressure chamber row L2.

[0060] FIG. 3 shows a heating lead electrode 94 including a heating lead electrode 94a and a heating lead electrode 94b. The heating lead electrode 94 functions as a connection part that connects the heating resistor 601 and the relay substrate 120. One end of the heating resistor 601 is connected to the heating lead electrode 94a, and the other end of the heating resistor 601 is connected to the heating lead electrode 94b. Thereby, the heating resistor 601 is electrically connected to the relay substrate 120, and the control unit 540 can apply a heating voltage for causing resistive heating to the heating resistor 601. In the example of FIG. 3, the heating resistor 601 is formed in a linear shape, but is not limited thereto, and may be formed, for example, in a so-called meandering pattern that reciprocates a plurality of times in the vicinity of the first pressure chamber row L1 and the second pressure chamber row L2.

[0061] In the present embodiment, the heating lead electrode 94 is formed in the same layer as the individual lead electrode 91 and the common lead electrode 92 and is formed to be electrically discontinuous. The material of the heating lead electrode 94 is a conductive material, for example, gold (Au), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), platinum (Pt), aluminum (Al), etc. In the present embodiment, gold (Au) is used as the heating lead electrode 94. The material of the heating lead electrode 94 is the same as that of the individual lead electrode 91 and the common lead electrode 92. The heating lead electrode 94 may have an adhesion layer that improves the adhesion to the heating resistor 601 and the diaphragm 50.

[0062] As shown in FIG. 5, in the present embodiment, a detection resistor 401 is further provided on the surface of the diaphragm 50 on the -Z direction side. Specifically, the detection resistor 401 is located between the diaphragm 50 and the piezoelectric body 70 in the Z-axis direction and is covered by the piezoelectric body 70. That is, the detection resistor 401 is arranged at the same position as the piezoelectric element 300, that is, in the same layer as the piezoelectric element 300, in the stacking direction of the piezoelectric element 300 with respect to the pressure chamber substrate 10. The detection resistor 401 is a conductor wiring used to detect the temperature of the pressure chamber 12. In the present embodiment, the temperature of the detection resistor 401 is detected by utilizing the characteristic that the electrical resistance value of a metal, semiconductor, or the like changes with temperature. When driving the piezoelectric element 300, the control unit 540 measures the electrical resistance value of the detection resistor 401 and detects the temperature of the pressure chamber 12 based on the correspondence relationship between the electrical resistance value of the detection resistor 401 and the temperature.

[0063] The material of the detection resistor 401 is a material having a temperature-dependent electrical resistance value. For example, gold (Au), platinum (Pt), iridium (Ir), aluminum (Al), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), etc. can be used. Among these, platinum (Pt) can be preferably adopted as the material of the detection resistor 401 from the viewpoints of large change in electrical resistance due to temperature and high stability and accuracy. The electrical resistance value is an example of the measured value of the detection resistor to be measured. In the present embodiment, the detection resistor 401 is made to be in the same layer as the heating resistor 601 and the first electrode 60 in the stacking direction, and is formed so as to be electrically discontinuous from the heating resistor 601 and the first electrode 60. The material of the detection resistor 401 is the same platinum (Pt) as that of the heating resistor 601 and the first electrode 60. Thereby, compared with the case where the detection resistor 401 is formed separately from the heating resistor 601 and the first electrode 60, the manufacturing process can be simplified and the cost can be reduced. The detection resistor 401 may be formed in a layer different from the heating resistor 601 and the first electrode 60.

[0064] As shown in FIG. 3, in the present embodiment, the detection resistor 401 is continuously formed so as to surround the first pressure chamber row L1 and the second pressure chamber row L2. FIG. 3 shows a measurement lead electrode 93 including a measurement lead electrode 93a and a measurement lead electrode 93b. The measurement lead electrode 93 functions as a connection portion that connects the detection resistor 401 and the relay substrate 120. One end of the detection resistor 401 is connected to the measurement lead electrode 93a, and the other end of the detection resistor 401 is connected to the measurement lead electrode 93b. Thereby, the detection resistor 401 is electrically connected to the relay substrate 120, and the control unit 540 can detect the electrical resistance value of the detection resistor 401. In the example of FIG. 3, the detection resistor 401 is formed in a linear shape, but is not limited thereto. For example, it may be formed in a so-called meandering pattern that reciprocates a plurality of times in the vicinity of the first pressure chamber row L1 and the second pressure chamber row L2. By configuring in this way, the detection accuracy of the temperature of the pressure chamber 12 can be increased.

[0065] In the present 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. The material of the measurement lead electrode 93 is a conductive material, for example, gold (Au), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), platinum (Pt), aluminum (Al), etc. In the present embodiment, gold (Au) is used as 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 have an adhesion layer that improves the adhesion to the detection resistor 401 and the diaphragm 50.

[0066] As shown in FIG. 3, a part of the detection resistor 401 is linearly formed along the arrangement direction of the pressure chambers 12 in the first pressure chamber row L1, and is disposed on the +X direction side of the pressure chambers 12 included in the first pressure chamber row L1, that is, outside the liquid ejection head 510 in the crossing direction. In the present embodiment, in other parts of the detection resistor 401, it is linearly formed along the arrangement direction of the pressure chambers 12 in the second pressure chamber row L2, and is disposed on the -X direction side of the pressure chambers 12 included in the second pressure chamber row L2, that is, outside the liquid ejection head 510 in the crossing direction. Thus, in the present embodiment, the detection resistor 401 is continuously formed outside the liquid ejection head 510 so as to surround the first pressure chamber row L1 and the second pressure chamber row L2. The detection resistor 401 is disposed inside the liquid ejection head 510 closer to the pressure chamber 12 than the heating resistor 601. By disposing the detection resistor 401 at a position close to the pressure chamber 12, the detection accuracy of the temperature of the pressure chamber 12 by the detection resistor 401 can be increased.

[0067] With reference to FIGS. 7 to 9, the functional configuration and arrangement method of the circuit board provided in the liquid ejection device 500 of the present embodiment will be described. FIG. 7 is a block diagram showing the functional configuration of the liquid ejection device 500. As shown in FIG. 7, the liquid ejection device 500 includes a print head 5 and a control board 580. The control board 580 is a board including a hardware logic circuit for realizing the functions of the control unit 540 described above. The control board 580 is formed using a rigid board and is disposed at a position different from the print head 5 inside the liquid ejection device 500. In the present embodiment, the control board 580 is separated from the wiring board 530 to reduce or suppress heat transfer from each electronic circuit of the control board 580 to the temperature detection circuit 400. As shown in FIG. 7, the print head 5 has a plurality of liquid ejection head units 51, and each of the liquid ejection head units 51 has a plurality of liquid ejection heads 510. Note that, hereinafter in FIG. 7 and later, the illustration of the ink tank 550, the conveyance mechanism 560, and the moving mechanism 570 is omitted.

[0068] The control board 580 and the print head 5 are communicably connected by a cable 590. In the present embodiment, the cable 590 electrically connects a terminal group provided on the control board 580 and a terminal group provided on the branch wiring board 520 included in the print head 5. As the cable 590, various cables corresponding to the form of the signal to be propagated, such as a flexible flat cable (FFC) or a coaxial cable, are used. The cable 590 may be an optical communication cable that propagates an optical signal.

[0069] Based on the image data input from a host computer or the like provided outside the liquid ejection device 500, the control board 580 generates a signal for controlling each component of the liquid ejection device 500 and outputs it to the corresponding component. The control board 580 includes a liquid ejection device control circuit 581, a signal conversion circuit 582, a time measurement circuit 583, a power supply circuit 584, a voltage detection circuit 585, a print head control circuit 586, and a drive signal output circuit 587. Note that the control board 580 is not limited to being composed of a single board, and may be composed of a plurality of boards. For example, at least a part of the plurality of circuits mounted on the control board 580 including the liquid ejection device control circuit 581, the signal conversion circuit 582, the time measurement circuit 583, the power supply circuit 584, the voltage detection circuit 585, the print head control circuit 586, and the drive signal output circuit 587 included in the control board 580 may be mounted on different boards and electrically connected by a connector or a cable (not shown).

[0070] Commercial power is input to the power supply circuit 584. The power supply circuit 584 converts the input commercial power into, for example, a DC voltage of 42V and outputs it. The DC voltage output from the power supply circuit 584 is input to the voltage detection circuit 585 and is also used as the power supply voltage for each component of the liquid ejection device 500. Here, each component of the liquid ejection device 500 may use the output DC voltage as it is as the power supply voltage and the drive voltage, or may use a voltage signal converted to various voltage values such as 3.3V, 5V, and 7.5V by a voltage conversion circuit (not shown) as the power supply voltage and the drive voltage.

[0071] The voltage detection circuit 585 detects whether a power supply voltage such as a commercial power supply is supplied to the liquid ejection device 500 based on the voltage value of the DC voltage output from the power supply circuit 584. Then, the voltage detection circuit 585 generates a voltage detection signal with a logic level corresponding to the detection result and outputs it to the time measurement circuit 583.

[0072] The time measurement circuit 583 determines whether a power supply voltage is supplied to the liquid ejection device 500 based on the input voltage detection signal. When the time measurement circuit 583 determines that a power supply voltage is supplied to the liquid ejection device 500 based on the voltage detection signal, it generates elapsed time information and outputs it to the liquid ejection device control circuit 581.

[0073] The liquid ejection device control circuit 581 generates various signals for controlling the operations of the respective parts of the liquid ejection device 500 and outputs them to the respective parts included in the liquid ejection device 500. A print head operation information signal including the driving status of the print head 5 is input to the liquid ejection device control circuit 581 from the print head control circuit 586.

[0074] The print head control circuit 586 generates a drive data signal for driving a plurality of piezoelectric elements 300 included in the print head 5, a print data signal SI for controlling the timing of supplying a drive signal COM to the piezoelectric elements 300, a clock signal SCK, a latch signal LAT, a change signal CH, and a switching signal SW. The print data signal SI, the clock signal SCK, the latch signal LAT, the change signal CH, and the switching signal SW generated by the print head control circuit 586 are input to the print head 5 via the cable 590. Note that the print head control circuit 586 generates and outputs a print data signal SI and a switching signal SW corresponding to each of the plurality of liquid ejection heads 510 included in the print head 5. The print head control circuit 586 generates a drive data signal that defines the waveform of the drive signal COM for driving the piezoelectric elements 300 and outputs it to the drive signal output circuit 587.

[0075] The drive signal output circuit 587 generates a drive signal COM by digitally / analog-converting each of the input drive data signals and then D-class amplifying the converted analog signals based on a DC voltage. In other words, the drive data signal is a digital signal that defines the waveform of the drive signal COM, and the drive signal output circuit 587 D-class amplifies the waveform defined by the drive data signal based on a DC voltage to generate a drive signal COM having a maximum voltage value sufficient to drive the piezoelectric element 300 and whose voltage value changes. The drive signal COM is input to the print head 5 via the cable 590. The drive data signal may be any signal that can define the waveform of the drive signal COM, for example, it may be an analog signal. The drive signal output circuit 587 only needs to be able to amplify the waveform defined by the drive data signal, and for example, it may be configured to include an A-class amplifier circuit, a B-class amplifier circuit, or an AB-class amplifier circuit, etc.

[0076] The print head control circuit 586 outputs a memory control signal for controlling the memory of the branch wiring board 520 described later. The control of the memory includes a read process of reading the information stored in the memory, a write process of writing information to the memory, and the like. When the memory control signal is output, a stored data signal corresponding to the information read from the memory is input to the print head control circuit 586.

[0077] As shown in FIG. 7, the print head 5 includes a branch wiring board 520 and a plurality of liquid ejection head units 51. The branch wiring board 520 is electrically connected to each of the plurality of liquid ejection head units 51 via the cable 522. The plurality of liquid ejection head units 51 included in the print head 5 all have the same configuration.

[0078] To the branch wiring board 520, a drive signal COM, a print data signal SI, a clock signal SCK, a latch signal LAT, a change signal CH, and a switching signal SW are input from the control board 580 via a cable 590. After each of the drive signal COM, the print data signal SI, the clock signal SCK, the latch signal LAT, the change signal CH, and the switching signal SW propagates through the branch wiring board 520, it is input to the corresponding liquid ejection head unit 51.

[0079] The branch wiring board 520 has an integrated circuit including a memory and a selector. The selector is provided corresponding to each liquid ejection head unit 51. Input to the selector are, for example, a print data signal SI, a memory control signal MC, a latch signal LAT, and a change signal CH input from the control board 580. The selector selects whether to output the print data signal SI, the latch signal LAT, and the change signal CH to the liquid ejection head unit 51 or to output the memory control signal MC, the latch signal LAT, and the change signal CH to the memory according to the logic levels of the input latch signal LAT and change signal CH. Stored in the memory is information indicating the operating state of the print head 5 and threshold information for determining whether to update the information. The memory in the present embodiment is an ultraviolet erasable non-volatile memory, specifically, a One-Time-PROM, an EPROM, etc. are used. The memory is controlled by a memory control signal MC, a clock signal SCK, a latch signal LAT, and a change signal CH input via the selector.

[0080] The functional configuration of the liquid ejection head unit 51 will be described with reference to FIG. 8. FIG. 8 is a block diagram showing the functional configuration of the liquid ejection head unit 51. As shown in FIG. 8, the liquid ejection head unit 51 has a wiring board 530, a liquid ejection head 510, and a relay board 120.

[0081] The wiring board 530 is a printed circuit board (PCB), for example, a rigid board such as a ceramic board or a glass epoxy board. The wiring board 530 is a so-called multilayer wiring board in which a plurality of layers are laminated. Each layer of the wiring board 530 to be laminated is also called a "wiring layer". The wiring board 530 is electrically connected to each of the plurality of liquid ejection heads 510 via the relay board 120. To the wiring board 530, a drive signal COM, a reference voltage signal VBS, a print data signal SI, a clock signal SCK, a latch signal LAT, a change signal CH, and a switching signal SW are respectively input from the branch wiring board 520 via the cable 522. Each of the drive signal COM, the reference voltage signal VBS, the print data signal SI, the clock signal SCK, the latch signal LAT, the change signal CH, and the switching signal SW input to the wiring board 530 is input to the relay board 120 after propagating through the wiring board 530. That is, the wiring board 530 branches and relays the drive signal COM, the reference voltage signal VBS, the print data signal SI, the clock signal SCK, the latch signal LAT, the change signal CH, and the switching signal SW between the branch wiring board 520 and the plurality of liquid ejection heads 510. The switching signal SW input to the relay board 120 switches whether the integrated circuit 121 outputs the drive voltage signal Vin or inputs the residual vibration Vout generated in the corresponding piezoelectric element 300 to the integrated circuit 121. The wiring board 530 may be various boards such as a flexible board or a rigid flexible board, not limited to a rigid board.

[0082] The relay board 120 connects the liquid ejection head 510 and the wiring board 530. The relay board 120 has an integrated circuit 121. The drive signal COM, print data signal SI, reference voltage signal VBS, clock signal SCK, latch signal LAT, change signal CH, and switch signal SW input to the relay board 120 are input to the integrated circuit 121. However, the reference voltage signal VBS may not be input to the integrated circuit 121 and may be input to the liquid ejection head 510 via the second circuit 532 and the relay board 120. In the present embodiment, the integrated circuit 121 has a switch and switches whether to apply the drive signal COM to the piezoelectric element 300 or to make it non-conductive. In the following description, the drive signal COM after the integrated circuit 121 is also referred to as the drive voltage signal Vin. The integrated circuit 121 controls whether to select the signal waveform included in the drive signal COM at the timing defined by the print data signal SI, clock signal SCK, latch signal LAT, and change signal CH, thereby generating the drive voltage signal Vin and outputting it to the first electrode 60 of the piezoelectric element 300 included in the liquid ejection head 510. The drive voltage signal Vin has a different potential for each ink ejection amount by the liquid ejection head 510. The integrated circuit 121 is likely to generate more heat than the wiring board 530.

[0083] The reference voltage signal VBS is supplied to the second electrode 80 of the piezoelectric element 300. The reference voltage signal VBS is a signal of a potential that serves as a reference for the displacement of the piezoelectric element 300, and is, for example, a signal of a potential such as a ground potential, DC5.5V, or DC6V. The reference voltage signal VBS has a constant potential regardless of the ejection amount from the liquid ejection head 510. In the present embodiment, the reference voltage signal VBS is generated by the drive signal output circuit 587. The reference voltage signal VBS is not limited to the drive signal output circuit 587 and may be generated by a voltage generation circuit (not shown). The piezoelectric element 300 included in the liquid ejection head 510 is driven according to the potential difference between the drive voltage signal Vin supplied to the first electrode 60 and the reference voltage signal VBS supplied to the second electrode 80. As a result, an amount of ink corresponding to the drive of the piezoelectric element 300 is ejected from the liquid ejection head 510.

[0084] The integrated circuit 121 included in the relay substrate 120 receives the residual vibration Vout generated in the liquid ejection head 510 driven based on the drive voltage signal Vin. The integrated circuit 121 may generate a residual vibration signal based on the input residual vibration Vout.

[0085] As shown in FIG. 8, in the present embodiment, the wiring substrate 530 includes a first circuit 531, a second circuit 532, and a temperature detection circuit 400. The first circuit 531 and the second circuit 532 include conductor wirings formed on the wiring substrate 530, electronic components and electronic circuits mounted on the wiring substrate 530, and the like. In the present embodiment, the first circuit 531 is a drive voltage wiring for outputting a drive signal COM for generating the drive voltage signal Vin to the relay substrate 120. In the present embodiment, the second circuit 532 is a reference voltage wiring for supplying the reference voltage signal VBS generated by the drive signal output circuit 587 and input to the wiring substrate 530 to the second electrode 80 which is a common electrode.

[0086] The temperature detection circuit 400 is electrically connected to the detection resistor 401 and detects a voltage value used to calculate the electrical resistance value of the detection resistor 401. The temperature detection circuit 400 includes a constant current circuit 430 and a voltage detection circuit 440. The constant current circuit 430 flows a constant current through the detection resistor 401 under the control of the control unit 540. The constant current circuit 430 may be provided not only on the wiring substrate 530 but also outside the wiring substrate 530, such as on the branch wiring substrate 520 or the control substrate 580. The voltage detection circuit 440 includes a differential amplifier circuit 442 and an A / D converter 444. The differential amplifier circuit 442 is an amplifier circuit that amplifies the voltage value generated in the detection resistor 401 by the current supplied from the constant current circuit 430, and an instrumentation amplifier can be used. The A / D converter 444 converts the input analog voltage value into a digital signal and outputs it to the control unit 540. Note that the differential amplifier circuit 442 can also be omitted.

[0087] With reference to FIG. 9, the layout of conductor wirings and the like of the wiring substrate 530 included in the liquid ejection head unit 51 of the present embodiment will be described. FIG. 9 is an explanatory diagram schematically showing the arrangement position of the temperature detection circuit 400 on the wiring substrate 530. In the example of FIG. 9, among the plurality of wiring layers of the wiring substrate 530, the wiring layer LY1 in which the first circuit 531 and the second circuit 532 are arranged is shown. In the wiring layer LY1, in addition to the first circuit 531 and the second circuit 532, the temperature detection circuit 400 is arranged. In FIG. 9, for ease of understanding of the technology, the regions occupied by the first circuit 531, the second circuit 532, and the temperature detection circuit 400 in the wiring layer LY1 of the wiring substrate 530 are each schematically shown in a block shape. The temperature detection circuit 400 may be formed across a plurality of layers of the wiring substrate 530. For example, it may include at least the wiring layer LY1 in which the first circuit 531 and the second circuit 532 are arranged and may be arranged across other wiring layers.

[0088] FIG. 9 shows a first distance D1, a second distance D2, and a third distance D3. The first distance D1 means the shortest distance between the first circuit 531 and the second circuit 532. The second distance D2 means the shortest distance between the first circuit 531 and the temperature detection circuit 400. The third distance D3 means the shortest distance between the second circuit 532 and the temperature detection circuit 400. In the example of FIG. 9, the first distance D1, the second distance D2, and the third distance D3 are each the shortest distance in a plan view in the wiring layer LY1. However, it is not limited to the shortest distance in a plan view, and the first distance D1, the second distance D2, and the third distance D3 may be the shortest distance in a three-dimensional space including the stacking direction of the wiring layers.

[0089] Here, when the temperature detection circuit 400 is disposed on the wiring board 530 inside the liquid ejection head 510, the measurement accuracy of the temperature by the temperature detection circuit 400 may decrease. The inventors newly found that the measurement accuracy of the temperature by the temperature detection circuit 400 may decrease due to the influence of heat and electrical noise from circuits and the like around the temperature detection circuit 400. The decrease in the detection accuracy of the temperature detection circuit 400 is particularly significant when a circuit for transmitting a signal for driving the piezoelectric element 300, such as a drive voltage wiring for outputting the drive signal COM to the relay board 120 and a reference voltage wiring for supplying the reference voltage signal VBS to the second electrode 80 which is a common electrode, is disposed.

[0090] In an inkjet type liquid ejection head 510 that ejects droplets using the piezoelectric element 300, for example, in order to adjust the amount of meniscus retraction and the strength of the return after retraction, a drive waveform with a large potential change with respect to time change, such as so-called pull-push-pull drive, may be applied to the piezoelectric element 300. Therefore, in the liquid ejection head unit 51, the amount of current flowing through the conductor wiring changes greatly, and the amount of heat generated in the electronic circuit changes greatly. As a result, it is presumed that this thermal change is transmitted to the temperature detection circuit 400 and the measurement accuracy of the temperature by the temperature detection circuit 400 is decreased. Further, when the amount of current flowing through the conductor wiring changes greatly, the inductive noise from circuits and the like around the temperature detection circuit 400 may increase. Therefore, it is presumed that this inductive noise is transmitted to the temperature detection circuit 400 and the measurement accuracy of the temperature by the temperature detection circuit 400 is decreased. From the above, the liquid ejection head unit 51 of the present embodiment is configured such that in the wiring board 530, conductors, electronic components, and electronic circuits are not disposed in a region up to a predetermined distance from the temperature detection circuit 400 from the viewpoint of reducing or preventing the influence of heat and electrical noise from circuits around the temperature detection circuit 400.

[0091] FIG. 9 shows a predetermined distance DN and a region NA from the temperature detection circuit 400 to the distance DN. The distance DN is a region where conductors, electronic components, electronic circuits, etc. are arranged, and the temperature detection circuit 400 can be affected by heat and electrical noise from surrounding circuits. That is, when circuits other than the temperature detection circuit 400, in the example of FIG. 9, the first circuit 531 or the second circuit 532 is arranged in the region NA, the measurement accuracy of the temperature by the temperature detection circuit 400 may decrease. The distance DN can be experimentally determined in advance, for example, by using the relationship between the distance from the temperature detection circuit 400 and the measurement accuracy of the temperature by the temperature detection circuit 400.

[0092] In the present embodiment, the first circuit 531 and the second circuit 532 are not arranged in the region NA. In other words, each of the second distance D2 and the third distance D3 is set to be longer than the distance DN, and the first circuit 531 and the second circuit 532 are provided at positions farther from the temperature detection circuit 400 than the predetermined distance DN. The first distance D1 between the first circuit 531 and the second circuit 532 can be set from the viewpoint of ensuring the quality such as insulation between the first circuit 531 and the second circuit 532 while avoiding an increase in the size of the wiring board 530. In the present embodiment, each of the second distance D2 and the third distance D3 is set to be longer than the first distance D1. By arranging the first circuit 531 and the second circuit 532 at positions farther from the first distance D1, it is possible to reduce or suppress the temperature detection circuit 400 from being affected by heat and electrical noise from surrounding circuits, and to improve the detection accuracy of the temperature by the temperature detection circuit 400. In the present embodiment, the distance DN is designed to be 0.5 mm from the viewpoint of avoiding an increase in the size of the wiring board 530 and avoiding being affected by heat and electrical noise from surrounding circuits. The distance DN is not limited to 0.5 mm, and from the viewpoint of avoiding being affected by heat and electrical noise from surrounding circuits, it is preferably 0.5 mm or more, and more preferably 1 mm or more.

[0093] As described above, the liquid ejection head unit 51 of the present embodiment includes a liquid ejection head 510 and a wiring board 530 electrically connected to the liquid ejection head 510. The liquid ejection head 510 is provided with a detection resistor 401 for detecting the temperature of the pressure chamber 12, and the wiring board 530 is provided with a first circuit 531, a second circuit 532, and a temperature detection circuit 400 electrically connected to the detection resistor 401. The first circuit 531, the second circuit 532, and the temperature detection circuit 400 are provided on the wiring board 530 such that a second distance D2 between the first circuit 531 and the temperature detection circuit 400 and a third distance D3 between the second circuit 532 and the temperature detection circuit 400 are each longer than a first distance D1 between the first circuit 531 and the second circuit 532. Therefore, according to the liquid ejection head unit 51 of the present embodiment, by arranging the first circuit 531 and the second circuit 532 at positions farther from the temperature detection circuit 400 than the first distance D1, it is possible to reduce or suppress the temperature detection circuit 400 from being affected by heat and electrical noise from surrounding circuits and the like, and it is possible to improve the detection accuracy of the temperature by the temperature detection circuit 400.

[0094] According to the liquid ejection head unit 51 of the present embodiment, the detection resistor 401 is arranged at the same position as the piezoelectric element 300, that is, in the same layer as the piezoelectric element 300, in the stacking direction of the piezoelectric element 300 with respect to the pressure chamber substrate 10. By arranging the detection resistor 401 in the vicinity of the pressure chamber 12 in the liquid ejection head 510, it is possible to improve the measurement accuracy of the temperature of the ink inside the pressure chamber 12 by the detection resistor 401.

[0095] According to the liquid ejection head unit 51 of the present embodiment, the temperature detection circuit 400 includes a constant current circuit 430 for flowing a constant current through the detection resistor 401. Therefore, it is possible to improve the measurement accuracy of the electrical resistance value of the detection resistor 401 by the temperature detection circuit 400 and improve the measurement accuracy of the temperature of the ink inside the pressure chamber 12.

[0096] According to the liquid ejection head unit 51 of the present embodiment, the temperature detection circuit 400 includes a voltage detection circuit 440 for detecting the voltage generated in the detection resistor 401 by the current flowing from the constant current circuit 430. By providing the voltage detection circuit 440 on the wiring board 530, the wiring length of the voltage detection circuit 440 can be shortened compared to the case where the voltage detection circuit 440 is arranged on another circuit board such as the control board 580, improving the measurement accuracy of the electrical resistance value of the detection resistor 401 by the temperature detection circuit 400 and improving the measurement accuracy of the temperature of the ink in the pressure chamber 12.

[0097] According to the liquid ejection head unit 51 of the present embodiment, there is provided a relay board 120 that connects the liquid ejection head 510 and the wiring board 530, and the relay board 120 is provided with an integrated circuit 121 that generates a drive voltage signal Vin for driving the piezoelectric element 300. By providing a drive IC with a larger heat generation amount than the wiring board 530 on a circuit board closer to the liquid ejection head 510 than the wiring board 530, heat conduction to the temperature detection circuit 400 can be reduced compared to the case where the integrated circuit 121 is provided on the wiring board 530.

[0098] According to the liquid ejection head unit 51 of the present embodiment, the wiring board 530 is a rigid board, and the relay board 120 is a flexible board. By making the relay board 120 on which the integrated circuit 121 is arranged a flexible board, while suppressing the enlargement of the liquid ejection head unit 51, by making the wiring board 530 provided with the temperature detection circuit 400 a rigid board, the influence of heat conduction and inductive noise to the temperature detection circuit 400 can be reduced compared to the case where the wiring board 530 is a flexible board.

[0099] According to the liquid ejection head unit 51 of the present embodiment, the first circuit 531 and the second circuit 532 are provided at positions farther than a predetermined distance DN from the temperature detection circuit 400. Therefore, it is possible to reduce or prevent the temperature detection circuit 400 from being affected by heat and electrical noise from the first circuit 531 and the second circuit 532.

[0100] In the liquid ejection head unit 51 of the present embodiment, the predetermined distance DN is 0.5 mm. Therefore, while avoiding an increase in the size of the wiring board 530, it is possible to reduce or prevent the temperature detection circuit 400 from being affected by heat and electrical noise from the first circuit 531 and the second circuit 532.

[0101] According to the liquid ejection head unit 51 of the present embodiment, the wiring board 530 includes a plurality of stacked wiring layers, and the first circuit 531, the second circuit 532, and the temperature detection circuit 400 are arranged on the same wiring layer LY1 among the plurality of wiring layers. Each of the second distance D2 and the third distance D3 is set to be longer than the first distance D1. By arranging the first circuit 531 and the second circuit 532 at positions farther away from the first distance D1, it is possible to reduce or suppress the temperature detection circuit 400 from being affected by heat and electrical noise from surrounding circuits and the like, and to improve the temperature detection accuracy by the temperature detection circuit 400.

[0102] According to the liquid ejection head unit 51 of the present embodiment, the piezoelectric element 300 includes a first electrode 60 which is an individual electrode, a second electrode 80 which is a common electrode, and a piezoelectric body 70 provided between the first electrode 60 and the second electrode 80. The first circuit 531 is a drive voltage wiring for supplying a drive signal COM for generating a drive voltage signal Vin to the individual electrodes. The drive signal COM has different voltage values for each liquid ejection amount. The second circuit 532 is a reference voltage wiring for supplying a reference voltage signal VBS having a constant voltage value regardless of the ejection amount to the common electrode. By arranging a circuit in which a decrease in the detection accuracy of the temperature detection circuit 400 is likely to be significant at a position farther away from the first distance D1 from the temperature detection circuit 400, the temperature detection accuracy by the temperature detection circuit 400 can be further improved.

[0103] In the liquid ejection head unit 51 of the present embodiment, the second distance D2 is longer than the third distance D3. Generally, the current value flowing through the drive voltage wiring for outputting the drive signal COM for generating the drive voltage signal Vin is larger than that of the reference voltage wiring for supplying the reference voltage signal VBS to the common electrode. Therefore, the amount of heat generated by the drive voltage wiring can be larger than that of the reference voltage wiring. According to the liquid ejection head unit 51 of the present embodiment, by separating the drive voltage wiring, which is more likely to generate a larger amount of heat than the reference voltage wiring, from the temperature detection circuit 400, heat transfer from the first circuit 531 and the second circuit 532 to the temperature detection circuit 400 can be further reduced.

[0104] B. Second Embodiment: The configuration of the liquid ejection head unit 51 as the second embodiment of the present disclosure will be described with reference to FIGS. 10 to 12. The liquid ejection head unit 51 of the second embodiment is different from the liquid ejection head unit 51 of the first embodiment in that it includes a wiring board 530b in which the arrangement positions of the first circuit 531 and the second circuit 532 are different, instead of the wiring board 530. FIG. 10 is an explanatory diagram schematically showing the arrangement relationship between the temperature detection circuit 400 and the first circuit 531 and the second circuit 532 on the wiring board 530b in a cross-sectional view. FIG. 11 is an explanatory diagram schematically showing the arrangement relationship between the temperature detection circuit 400 and the first circuit 531 on the wiring board 530b in a plan view. FIG. 12 is an explanatory diagram schematically showing the arrangement relationship between the temperature detection circuit 400 and the second circuit 532 on the wiring board 530b in a plan view. The cross-sectional view shown in FIG. 10 corresponds to the cross-sectional view at the XII-XII position shown in FIGS. 11 and 12.

[0105] As shown in FIG. 10, the wiring board 530b is formed by laminating a plurality of wiring layers. In the present embodiment, the wiring board 530b has three wiring layers, namely, the wiring layer LY1 to the wiring layer LY3, laminated thereon. The temperature detection circuit 400 is formed across two of the wiring layers, namely, the wiring layer LY1 to the wiring layer LY2.

[0106] As shown in FIG. 11, the first circuit 531 is provided in the wiring layer LY1 among the wiring layers LY1 to LY3. The second distance D2 is the shortest distance from the first circuit 531 to the temperature detection circuit 400 in the plan view of the wiring layer LY1. As shown in FIG. 12, the second circuit 532 is provided in the wiring layer LY2 among the wiring layers LY1 to LY3. The third distance D3 is the shortest distance from the first circuit 531 to the temperature detection circuit 400 in the plan view of the wiring layer LY2.

[0107] As shown in FIGS. 10 to 12, the region NA includes the region from the temperature detection circuit 400 to a predetermined distance DN in the stacking direction of the wiring layers LY1 to LY3. Note that the first distance D1, the second distance D2, and the third distance D3 also mean the shortest distance in the three-dimensional space including the stacking direction. In the example of FIG. 10, the first distance D1 is the shortest distance in the stacking direction between the first circuit 531 and the second circuit 532.

[0108] As shown in FIGS. 10 to 12, the first circuit 531 is arranged in the wiring layer LY1 at a position directly above the second circuit 532 in the wiring layer LY2. That is, the first circuit 531 and the second circuit 532 are arranged at positions overlapping each other in the plan view on the wiring board 530b. In contrast, in the present embodiment, the first circuit 531 and the second circuit 532 are not arranged at positions overlapping the temperature detection circuit 400 in the plan view on the wiring board 530b. The position overlapping the temperature detection circuit 400 in the plan view on the wiring board 530b is, for example, the region NL directly below the temperature detection circuit 400 in the wiring layer LY3. In the present embodiment, further, from the viewpoint of reducing the heat transfer to the temperature detection circuit 400 and the influence of induced noise, the conductor wirings, electronic components, and electronic circuits other than the first circuit 531 and the second circuit 532 are not arranged in the region NL and the region NA.

[0109] According to the liquid ejection head unit 51 of the present embodiment, the first circuit 531 and the second circuit 532 are arranged at positions that do not overlap with the temperature detection circuit 400 in a plan view. Therefore, heat transfer and induced noise from the first circuit 531 and the second circuit 532 to the temperature detection circuit 400 in the stacking direction can be reduced or suppressed, and the temperature detection accuracy by the temperature detection circuit 400 can be improved.

[0110] According to the liquid ejection head unit 51 of the present embodiment, the wiring board 530b includes a plurality of stacked wiring layers LY1 to LY3. The first circuit 531 and the second circuit 532 are arranged on different wiring layers among the plurality of wiring layers LY1 to LY3. The first distance D1 is the shortest distance in the stacking direction between the first circuit 531 and the second circuit 532. The second distance D2 is the shortest distance from the first circuit 531 to the temperature detection circuit 400 in a plan view of the wiring layer LY1, and the third distance D3 is the shortest distance from the first circuit 531 to the temperature detection circuit 400 in a plan view of the wiring layer LY2. By arranging the first circuit 531 and the second circuit 532 at positions farther than the first distance D1 in the stacking direction, it is possible to reduce or suppress the temperature detection circuit 400 from being affected by heat and electrical noise from surrounding circuits and the like, and the temperature detection accuracy by the temperature detection circuit 400 can be improved.

[0111] C. Other forms: (C1) In each of the above embodiments, the first circuit 531 functions as a drive voltage wiring for supplying a drive voltage signal Vin different for each ink discharge amount by the liquid discharge head 510 to the first electrode 60 which is an individual wiring, and the second circuit 532 functions as a reference voltage wiring for supplying a reference voltage signal VBS which is constant regardless of the ink discharge amount by the liquid discharge head 510 to the second electrode 80 which is a common electrode. On the other hand, the first circuit 531 may be a reference voltage wiring and the second circuit 532 may be a drive voltage wiring. However, the first circuit 531 and the second circuit 532 are not limited to the drive voltage wiring and the reference voltage wiring, and for example, may be a heating voltage wiring for applying a heating voltage for generating resistance heating to the heating resistor 601. According to the liquid discharge head unit 51 of this embodiment, when the wiring board 530 includes a heating voltage wiring, it is possible to reduce or suppress the temperature detection circuit 400 from being affected by heat or electrical noise from the heating voltage wiring. Further, the first circuit 531 and the second circuit 532 may be a ground wiring for grounding the temperature detection circuit 400. According to the liquid discharge head unit 51 of this embodiment, when the wiring board 530 includes a ground wiring, it is possible to reduce or suppress the temperature detection circuit 400 from being affected by heat or electrical noise from the ground wiring. The first circuit 531 and the second circuit 532 may be conductor wirings for outputting the print data signal SI, the clock signal SCK, the latch signal LAT, the change signal CH, and the switching signal SW input from the branch wiring board 520 to the relay board 120.

[0112] (C2) In each of the above embodiments, an example is shown in which a control board 580 provided with a drive signal output circuit 587 for generating a drive signal COM input to the integrated circuit 121 for generating the drive voltage signal Vin is provided in the liquid discharge device 500. On the other hand, the control board 580 may be provided in the liquid discharge head unit 51. According to the liquid discharge head unit 51 of this embodiment, it is possible to provide the liquid discharge head unit 51 with a function of controlling the discharge of ink.

[0113] (C3) In the liquid ejection head unit 51 of each of the above embodiments, the wiring board 530 may further include a circuit breaker such as an electromagnetic removal filter, which is different from the first circuit 531 and the second circuit 532. The circuit breaker blocks the transmission of the drive signal COM and the reference voltage signal VBS to the temperature detection circuit 400. The first circuit 531, the second circuit 532, the temperature detection circuit 400, and the circuit breaker may be arranged on the wiring board 530 such that a fourth distance from the circuit breaker to the temperature detection circuit 400 is shorter than either the second distance D2 or the third distance D3. According to the liquid ejection head unit 51 of this embodiment, the circuit breaker can block the transmission of the drive signal COM and the reference voltage signal VBS to the temperature detection circuit 400, and reduce or suppress the influence of electrical noise from the first circuit 531 and the second circuit 532 on the temperature detection circuit 400.

[0114] (C4) In each of the above embodiments, an example is shown in which the entire area of the temperature detection circuit 400 is arranged to be separated from the first circuit 531 and the second circuit 532 by a distance longer than the first distance D1. However, only a specific portion of the temperature detection circuit 400 where the detection error becomes particularly large due to being provided at a position close to the first circuit 531 and the second circuit 532 may be arranged to be separated from the first circuit 531 and the second circuit 532 by a distance longer than the first distance D1. This specific portion includes, for example, the constant current circuit 430 and the voltage detection circuit 440. At least one of the constant current circuit 430 and the voltage detection circuit 440 can also be arranged to be separated from the first circuit 531 and the second circuit 532 by a distance longer than the first distance D1.

[0115] (C5) In each of the above embodiments, the temperature detection circuit 400 is composed of a continuous member. However, the temperature detection circuit 400 may be composed of a plurality of members. In this case, it is sufficient that each of the plurality of members constituting the temperature detection circuit 400 is provided at a distance longer than the first distance D1 from the first circuit 531 and the second circuit 532.

[0116] The present disclosure is not limited to the above-described embodiments and can be implemented in various configurations without departing from the gist thereof. For example, the technical features in the embodiments corresponding to the technical features in each form described in the summary of the invention can be appropriately replaced or combined in order to solve some or all of the above-described problems or to achieve some or all of the above-described effects. Further, if the technical feature is not described as essential in this specification, it can be appropriately deleted.

[0117] (1) According to one embodiment of the present disclosure, a liquid ejection head unit is provided. This liquid ejection head unit includes a pressure chamber substrate having a plurality of pressure chambers, a piezoelectric element laminated on the pressure chamber substrate to apply pressure to each of the plurality of pressure chambers, and a liquid ejection head provided with drive wiring for applying a voltage for driving the piezoelectric element to the piezoelectric element, and a wiring substrate electrically connected to the liquid ejection head. A detection resistor formed of the same material as the piezoelectric element or the drive wiring is provided in the liquid ejection head for detecting the temperature of the pressure chamber. The wiring substrate is provided with a first circuit, a second circuit different from the first circuit, and a temperature detection circuit electrically connected to the detection resistor. The first circuit, the second circuit, and the temperature detection circuit are provided on the wiring substrate such that the distance between the first circuit and the second circuit is a first distance, the distance between the first circuit and the temperature detection circuit is a second distance longer than the first distance, and the distance between the second circuit and the temperature detection circuit is a third distance longer than the first distance. According to this liquid ejection head unit, by arranging the first circuit and the second circuit at positions farther from the temperature detection circuit than the first distance, it is possible to reduce or suppress the temperature detection circuit from being affected by heat and electrical noise from the first circuit and the second circuit, and it is possible to improve the detection accuracy of the temperature by the temperature detection circuit.

[0118] (2) In the liquid ejection head unit of the above-described form, at least a part of the detection resistor may be disposed at the same position as the piezoelectric element in the stacking direction of the piezoelectric element with respect to the pressure chamber substrate. According to the liquid ejection head unit of this form, by disposing the detection resistor near the pressure chamber, the measurement accuracy of the temperature of the pressure chamber by the detection resistor can be improved.

[0119] (3) In the liquid ejection head unit of the above-described form, the temperature detection circuit may include a constant current circuit for flowing a constant current through the detection resistor. According to the liquid ejection head unit of this form, the measurement accuracy of the electrical resistance value of the detection resistor by the temperature detection circuit can be improved, and the measurement accuracy of the temperature of the pressure chamber can be improved.

[0120] (4) In the liquid ejection head unit of the above-described form, it may include a voltage detection circuit for detecting the voltage generated in the detection resistor by the current flowing from the constant current circuit. According to the liquid ejection head unit of this form, compared with the case where the voltage detection circuit is disposed outside the liquid ejection head unit, the wiring length of the voltage detection circuit can be shortened, and the measurement accuracy of the electrical resistance value of the detection resistor by the temperature detection circuit can be improved.

[0121] (5) In the liquid ejection head unit of the above-described form, further, a relay substrate for connecting the liquid ejection head and the wiring substrate, the relay substrate provided with an integrated circuit for generating a drive voltage signal for driving the piezoelectric element may be provided. According to the liquid ejection head unit of this form, by providing a drive IC having a larger heat generation amount than the wiring substrate on a circuit board at a position closer to the liquid ejection head than the wiring substrate, heat conduction to the temperature detection circuit can be reduced.

[0122] (6) In the liquid ejection head unit of the above-described embodiment, the wiring board may be a rigid board, and the relay board may be a flexible board. According to the liquid ejection head unit of this embodiment, by using a flexible board as the relay board on which the integrated circuit is disposed, while suppressing the increase in size of the liquid ejection head unit, by using a rigid board as the wiring board provided with the temperature detection circuit, compared with the case where the wiring board is a flexible board, the influence of heat conduction and inductive noise on the temperature detection circuit can be reduced.

[0123] (7) In the liquid ejection head unit of the above-described embodiment, further, a control board different from the wiring board and the relay board, and a drive signal output circuit for generating a drive signal input to the integrated circuit that generates the drive voltage signal may be provided. According to the liquid ejection head unit of this embodiment, a function of controlling the ejection of liquid can be provided to the liquid ejection head unit.

[0124] (8) In the liquid ejection head unit of the above-described embodiment, the first circuit and the second circuit may be disposed at positions that do not overlap the temperature detection circuit in a plan view. According to the liquid ejection head unit of this embodiment, heat transfer and inductive noise from the first circuit and the second circuit to the temperature detection circuit in the stacking direction can be reduced or suppressed, and the detection accuracy of the temperature by the temperature detection circuit can be improved.

[0125] (9) In the liquid ejection head unit of the above-described embodiment, the first circuit and the second circuit may be provided at positions farther than a predetermined distance from the temperature detection circuit. According to the liquid ejection head unit of this embodiment, it is possible to reduce or prevent the temperature detection circuit from being affected by heat and electrical noise from the first circuit and the second circuit.

[0126] (10) In the liquid ejection head unit of the above-described form, the predetermined distance may be 0.5 mm. According to the liquid ejection head unit of this form, while avoiding an increase in the size of the wiring board, it is possible to reduce or prevent the temperature detection circuit from being affected by heat and electrical noise from the first circuit and the second circuit.

[0127] (11) In the liquid ejection head unit of the above-described form, the wiring board may include a plurality of laminated wiring layers. The first circuit and the second circuit may be arranged on the same wiring layer among the plurality of wiring layers. The temperature detection circuit may be arranged at least on the same wiring layer. The first distance is the distance from the first circuit to the second circuit in a plan view of the same wiring layer, the second distance is the distance from the first circuit to the temperature detection circuit in a plan view of the same wiring layer, and the third distance may be the distance from the second circuit to the temperature detection circuit in a plan view of the same wiring layer. According to the liquid ejection head unit of this form, it is possible to reduce or suppress the temperature detection circuit from being affected by heat and electrical noise from surrounding circuits and the like, and it is possible to improve the detection accuracy of the temperature by the temperature detection circuit.

[0128] (12) In the liquid ejection head unit of the above-described form, the wiring board may include a plurality of laminated wiring layers. The first circuit and the second circuit may be respectively arranged on different wiring layers among the plurality of wiring layers. The first distance is the distance from the first circuit to the second circuit in the stacking direction of the plurality of wiring layers, the second distance is the distance from the first circuit to the temperature detection circuit in a plan view of the wiring board, and the third distance may be the distance from the second circuit to the temperature detection circuit in a plan view of the wiring board. According to the liquid ejection head unit of this form, it is possible to reduce or suppress the temperature detection circuit from being affected by heat and electrical noise from surrounding circuits and the like, and it is possible to improve the detection accuracy of the temperature by the temperature detection circuit.

[0129] (13) In the liquid ejection head unit of the above-described form, the piezoelectric element may include an individual electrode provided individually for each of the plurality of pressure chambers, a common electrode provided commonly for the plurality of pressure chambers, and a piezoelectric body provided between the individual electrode and the common electrode. The first circuit may be a drive voltage wiring that outputs a drive signal having a different voltage value for each liquid ejection amount, and the second circuit may be a reference voltage wiring for supplying a reference voltage signal having a constant voltage value regardless of the ejection amount to the common electrode. According to the liquid ejection head unit of this form, by arranging a circuit in which a decrease in the detection accuracy of the temperature detection circuit is likely to be significant at a position farther from the temperature detection circuit than the first distance, the temperature detection accuracy by the temperature detection circuit can be further improved.

[0130] (14) In the liquid ejection head unit of the above-described form, the second distance may be longer than the third distance. According to the liquid ejection head unit of this form, by separating the drive voltage wiring, which is more likely to generate a larger amount of heat than the reference voltage wiring, from the temperature detection circuit, heat transfer from the first circuit and the second circuit to the temperature detection circuit can be further reduced.

[0131] (15) In the liquid ejection head unit of the above-described form, the wiring board may further include a cutoff circuit different from the first circuit and the second circuit for cutting off transmission of the drive signal and the reference voltage signal to the temperature detection circuit. The first circuit, the second circuit, the temperature detection circuit, and the cutoff circuit may be provided on the wiring board such that the distance from the cutoff circuit to the temperature detection circuit is a fourth distance shorter than either the second distance or the third distance. According to the liquid ejection head unit of this form, the cutoff circuit can cut off transmission of the drive signal and the reference voltage signal to the temperature detection circuit, and it is possible to reduce or suppress the temperature detection circuit from being affected by electrical noise from the first circuit and the second circuit.

[0132] (16) In the liquid ejection head unit of the above-described form, the liquid ejection head may further include a heating resistor for heating the liquid inside the pressure chamber. At least one of the first circuit and the second circuit may be a heating voltage wiring for applying a heating voltage that generates resistive heating to the heating resistor. According to the liquid ejection head unit of this form, when the wiring board includes the heating voltage wiring, it is possible to reduce or suppress the temperature detection circuit from being affected by heat or electrical noise from the heating voltage wiring.

[0133] (17) In the liquid ejection head unit of the above-described form, at least one of the first circuit and the second circuit may be a ground wiring for grounding the temperature detection circuit. According to the liquid ejection head unit of this form, when the wiring board includes the ground wiring, it is possible to reduce or suppress the temperature detection circuit from being affected by heat or electrical noise from the ground wiring.

[0134] (18) In the liquid ejection head unit of the above-described form, at least one of the first circuit and the second circuit may be a logic circuit.

[0135] (19) According to another form of the present disclosure, a liquid ejection device is provided. This liquid ejection device includes the liquid ejection head unit of the above-described form and a liquid storage unit that stores the liquid ejected from the liquid ejection head unit. According to this liquid ejection device, by arranging the first circuit and the second circuit at a position farther from the temperature detection circuit than the first distance, it is possible to reduce or suppress the temperature detection circuit from being affected by heat or electrical noise from the first circuit and the second circuit, and it is possible to improve the detection accuracy of the temperature by the temperature detection circuit.

[0136] The present disclosure can also be realized in various forms other than the liquid ejection head unit and the liquid ejection device. For example, it can be realized in the form of a manufacturing method of the liquid ejection head unit, a manufacturing method of the liquid ejection device, and the like.

[0137] The present disclosure is not limited to inkjet systems, and can also be applied to any liquid ejection device that ejects liquids other than ink, and to liquid ejection heads used in such liquid ejection devices. For example, it can be applied to various liquid ejection devices and their liquid ejection heads as follows. (1) An image recording device such as a facsimile machine. (2) A colorant ejection device used in the manufacture of color filters for image display devices such as liquid crystal displays. (3) An electrode material ejection device used for forming electrodes in organic EL (Electro Luminescence) displays, field emission displays (FEDs), etc. (4) A liquid ejection device that ejects a liquid containing a biological organic substance used in the manufacture of biochips. (5) A sample ejection device as a precision pipette. (6) A lubricating oil ejection device. (7) A resin liquid ejection device. (8) A liquid ejection device that precisely ejects lubricating oil 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 a micro hemisphere lens (optical lens) used in optical communication elements, etc. (10) A liquid ejection device that ejects an acidic or alkaline etching liquid for etching a substrate, etc. (11) A liquid ejection device equipped with a liquid consumption head that ejects any other minute droplets.

[0138] "Droplet" refers to the state of the liquid discharged from the liquid ejection device, including granular, teardrop-shaped, and those trailing in a filamentous form. Also, the "liquid" here may be any material that can be consumed by the liquid ejection device. For example, the "liquid" may be a material in a state when the substance is in a liquid phase, including highly viscous or low-viscosity liquid-state materials, and liquid-state materials such as sols, gels, water, other inorganic solvents, organic solvents, solutions, liquid resins, and liquid metals (molten metals). In addition, not only liquids as a state of matter but also materials in which particles of functional materials composed of solids such as pigments and metal particles are dissolved, dispersed, or mixed in a solvent are included in the "liquid". Also, as typical examples of the combination of the first liquid and the second liquid, in addition to the combination of ink and reaction liquid as described in the above embodiment, the following are included. (1) The main agent and curing agent of the adhesive (2) The base paint and thinner of the paint, and the clear paint and thinner (3) The main solvent and diluting solvent containing cells of the ink for cells (4) The metallic leaf pigment dispersion liquid and diluting solvent of the ink (metallic ink) that exhibits a metallic luster (5) Gasoline, light oil, and biofuel for vehicle fuel (6) The main drug component and protective component of the drug (7) The phosphor and encapsulant of the light-emitting diode (LED)

Explanation of symbols

[0139] 5... Print head, 10... Pressure chamber substrate, 11... Partition wall, 12... Pressure chamber, 12a, 12b... Ends, 15... Communication plate, 16... Nozzle communication path, 17... First manifold part, 18... Second manifold part, 19... Supply communication path, 20... Nozzle plate, 21... Nozzle, 30... Protection substrate, 31... Holding part, 32... Through hole, 40... Case member, 41... Accommodation part, 42... Third manifold part, 43... Connection port, 44... Supply port, 45... Compliance substrate, 46... Sealing film, 47... Fixed substrate, 48... Opening, 49... Compliance part, 50... Diaphragm, 51... Liquid ejection head unit, 55... Elastic film, 56... Insulator film, 60... First electrode, 60a, 60b... Ends, 70... Piezoelectric body, 70a, 70b... Ends, 71... Groove part, 80... Second electrode, 80a, 80b... Ends, 85... Wiring part, 91... Individual lead electrode, 92... Common lead electrode, 92a, 92b... Extended parts, 93, 93a, 93b... Measurement lead electrodes, 94, 94a, 94b... Heating lead electrodes, 100... Manifold, 120... Relay substrate, 121... Integrated circuit, 300... Piezoelectric element, 310... Active part, 320... Inactive part, 400... Temperature detection circuit, 401... Detection resistor, 430... Constant current circuit, 440... Voltage detection circuit, 442... Differential amplifier circuit, 444... A / D converter, 500... Liquid ejection device, 510... Liquid ejection head, 520... Branch wiring substrate, 522... Cable, 530, 530b... Wiring substrate, 531... First circuit, 532... Second circuit, 550... Ink tank, 552... Tube, 560... Conveying mechanism, 562... Conveying roller, 564... Conveying rod, 566... Conveying motor, 570... Moving mechanism, 572... Carriage, 574... Conveying belt, 576... Moving motor, 577... Pulley, 580... Control substrate, 581... Liquid ejection device control circuit, 582... Signal conversion circuit, 583... Time measurement circuit, 584... Power supply circuit, 585... Voltage detection circuit, 586... Print head control circuit, 587... Drive signal output circuit, 590... Cable, 601... Heating resistor, L1... First pressure chamber row, L2... Second pressure chamber row, LY1~LY3... Wiring layer, NA, NL... Regions, P... Printing paper

Claims

1. A liquid ejection head unit, comprising: a pressure chamber substrate having a plurality of pressure chambers; a piezoelectric element laminated on the pressure chamber substrate for applying pressure to each of the plurality of pressure chambers, the piezoelectric element including an individual electrode provided individually for each of the plurality of pressure chambers, a common electrode provided commonly for the plurality of pressure chambers, and a piezoelectric body provided between the individual electrode and the common electrode; a driving wiring for applying a voltage for driving the piezoelectric element to the piezoelectric element; and a liquid ejection head provided with a diaphragm, a wiring substrate electrically connected to the liquid ejection head, wherein a detection resistor formed of the same material as the piezoelectric element or the driving wiring is provided in the liquid ejection head for detecting the temperature of the pressure chamber, wherein a driving voltage wiring for outputting a driving signal having a different voltage value for each liquid ejection amount, a reference voltage wiring for supplying a reference voltage signal having a constant voltage value regardless of the ejection amount to the common electrode, and a temperature detection circuit electrically connected to the detection resistor are provided on the wiring substrate, wherein the temperature detection circuit includes at least one of a constant current circuit for flowing a constant current through the detection resistor and a voltage detection circuit for detecting a voltage generated in the detection resistor by the constant current, wherein the driving voltage wiring, the reference voltage wiring, and the temperature detection circuit are not electrically connected to each other on the wiring substrate, the driving voltage wiring, the reference voltage wiring, and the temperature detection circuit are arranged on the wiring substrate such that a distance between the driving voltage wiring and the reference voltage wiring is a first distance, a distance between the driving voltage wiring and the temperature detection circuit is a second distance longer than the first distance, and a distance between the reference voltage wiring and the temperature detection circuit is a third distance longer than the first distance, a liquid ejection head unit.

2. A liquid ejection head unit, comprising: a pressure chamber substrate having a plurality of pressure chambers; a piezoelectric element laminated on the pressure chamber substrate for applying pressure to each of the plurality of pressure chambers, the piezoelectric element including an individual electrode provided individually for each of the plurality of pressure chambers, a common electrode provided commonly for the plurality of pressure chambers, and a piezoelectric body provided between the individual electrode and the common electrode; and a liquid ejection head provided with a driving wiring for applying a voltage for driving the piezoelectric element to the piezoelectric element, A wiring board electrically connected to the liquid ejection head, The liquid ejection head is provided with a detection resistor formed of the same material as the piezoelectric element or the drive wiring for detecting the temperature of the pressure chamber, The wiring board is provided with a drive voltage wiring for outputting a drive signal having a different voltage value for each liquid ejection amount, a reference voltage wiring for supplying a reference voltage signal having a constant voltage value regardless of the ejection amount to the common electrode, and a temperature detection circuit electrically connected to the detection resistor, The drive voltage wiring, the reference voltage wiring, and the temperature detection circuit are not electrically connected to each other on the wiring board, The drive voltage wiring, the reference voltage wiring, and the temperature detection circuit, The distance between the drive voltage wiring and the reference voltage wiring is a first distance, The distance between the drive voltage wiring and the temperature detection circuit is a second distance longer than the first distance, The wiring board is provided such that the distance between the reference voltage wiring and the temperature detection circuit is a third distance longer than the first distance, Furthermore, a relay board for connecting the liquid ejection head and the wiring board, the relay board being provided with an integrated circuit for generating a drive voltage signal for driving the piezoelectric element, Liquid ejection head unit.

3. A liquid ejection head unit, A pressure chamber substrate having a plurality of pressure chambers, a piezoelectric element laminated on the pressure chamber substrate for applying pressure to each of the plurality of pressure chambers, an individual electrode provided individually for the plurality of pressure chambers, a common electrode provided commonly for the plurality of pressure chambers, and a piezoelectric body provided between the individual electrode and the common electrode, a liquid ejection head provided with a drive wiring for applying a voltage for driving the piezoelectric element to the piezoelectric element, A wiring board electrically connected to the liquid ejection head, The liquid ejection head is provided with a detection resistor formed of the same material as the piezoelectric element or the drive wiring for detecting the temperature of the pressure chamber, The wiring board is provided with a drive voltage wiring for outputting a drive signal having a different voltage value for each liquid ejection amount, a reference voltage wiring for supplying a reference voltage signal having a constant voltage value regardless of the ejection amount to the common electrode, and a temperature detection circuit electrically connected to the detection resistor, The drive voltage wiring, the reference voltage wiring, and the temperature detection circuit are not electrically connected to each other on the wiring substrate. The drive voltage wiring, the reference voltage wiring, and the temperature detection circuit The distance between the drive voltage wiring and the reference voltage wiring is a first distance. The distance between the drive voltage wiring and the temperature detection circuit is a second distance longer than the first distance. The wiring substrate is provided such that the distance between the reference voltage wiring and the temperature detection circuit is a third distance longer than the first distance. The wiring substrate further includes a cutoff circuit different from the drive voltage wiring and the reference voltage wiring for cutting off transmission of the drive signal and the reference voltage signal to the temperature detection circuit. The drive voltage wiring, the reference voltage wiring, the temperature detection circuit, and the cutoff circuit are provided on the wiring substrate such that the distance from the cutoff circuit to the temperature detection circuit is a fourth distance shorter than either the second distance or the third distance. Liquid ejection head unit.

4. A liquid ejection head unit according to any one of claims 1 to 3, At least a part of the detection resistor is disposed at the same position as the piezoelectric element in the stacking direction of the piezoelectric element with respect to the pressure chamber substrate. Liquid ejection head unit.

5. A liquid ejection head unit according to any one of claims 1 to 4, The temperature detection circuit includes a constant current circuit for passing a constant current through the detection resistor. Liquid ejection head unit.

6. A liquid ejection head unit according to claim 5, The temperature detection circuit includes a voltage detection circuit for detecting a voltage generated in the detection resistor by the current flowing from the constant current circuit. Liquid ejection head unit.

7. A liquid ejection head unit according to claim 2, The wiring substrate is a rigid substrate, The relay substrate is a flexible substrate. Liquid ejection head unit.

8. A liquid ejection head unit according to claim 2 or claim 7, Further provided is a control substrate different from the wiring substrate and the relay substrate, the control substrate being provided with a drive signal output circuit for generating a drive signal input to the integrated circuit that generates the drive voltage signal. Liquid ejection head unit.

9. The liquid ejection head unit according to any one of claims 1 to 8, wherein the drive voltage wiring and the reference voltage wiring are arranged at positions that do not overlap with the temperature detection circuit in a plan view, Liquid ejection head unit.

10. The liquid ejection head unit according to any one of claims 1 to 9, wherein the drive voltage wiring and the reference voltage wiring are provided at positions farther than a predetermined distance from the temperature detection circuit, Liquid ejection head unit.

11. The liquid ejection head unit according to claim 10, wherein the predetermined distance is 0.5 mm.

12. The liquid ejection head unit according to any one of claims 1 to 11, wherein the wiring board includes a plurality of laminated wiring layers, the drive voltage wiring and the reference voltage wiring are arranged in the same wiring layer among the plurality of wiring layers, the temperature detection circuit is arranged in at least the same wiring layer, the first distance is the distance from the drive voltage wiring to the reference voltage wiring in a plan view of the same wiring layer, the second distance is the distance from the drive voltage wiring to the temperature detection circuit in a plan view of the same wiring layer, the third distance is the distance from the reference voltage wiring to the temperature detection circuit in a plan view of the same wiring layer, Liquid ejection head unit.

13. The liquid ejection head unit according to any one of claims 1 to 11, wherein the wiring board includes a plurality of laminated wiring layers, the drive voltage wiring and the reference voltage wiring are respectively arranged in different wiring layers among the plurality of wiring layers, the first distance is the distance from the drive voltage wiring to the reference voltage wiring in the stacking direction of the plurality of wiring layers, the second distance is the distance from the drive voltage wiring to the temperature detection circuit in a plan view of the wiring board, the third distance is the distance from the reference voltage wiring to the temperature detection circuit in a plan view of the wiring board, Liquid ejection head unit.

14. The liquid ejection head unit according to any one of claims 1 to 13, wherein the second distance is longer than the third distance.

15. A liquid ejection head unit, A pressure chamber substrate having a plurality of pressure chambers, a piezoelectric element laminated on the pressure chamber substrate for applying pressure to each of the plurality of pressure chambers, an individual electrode provided individually for the plurality of pressure chambers, a common electrode provided commonly for the plurality of pressure chambers, and a piezoelectric body provided between the individual electrode and the common electrode, a piezoelectric element including the above, a drive wiring for applying a voltage for driving the piezoelectric element to the piezoelectric element, and a liquid discharge head provided with a heating resistor for heating the liquid inside the pressure chamber A wiring substrate electrically connected to the liquid discharge head The liquid discharge head is provided with a detection resistor formed of the same material as the piezoelectric element or the drive wiring for detecting the temperature of the pressure chamber The wiring substrate is provided with a wiring portion which is one of a drive voltage wiring for outputting a drive signal having a different voltage value for each discharge amount of the liquid and a reference voltage wiring for supplying a reference voltage signal having a constant voltage value regardless of the discharge amount to the common electrode, a heating voltage wiring for applying a heating voltage for generating resistance heating to the heating resistor, and a temperature detection circuit electrically connected to the detection resistor The wiring portion, the heating voltage wiring, and the temperature detection circuit are not electrically connected to each other on the wiring substrate The wiring portion, the heating voltage wiring, and the temperature detection circuit The distance between the wiring portion and the heating voltage wiring is a first distance The distance between the wiring portion and the temperature detection circuit is a second distance longer than the first distance The wiring substrate is provided such that the distance between the heating voltage wiring and the temperature detection circuit is a third distance longer than the first distance Liquid discharge head unit

16. A liquid discharge head unit according to any one of Claims 1 to 15 A liquid storage unit for storing the liquid discharged from the liquid discharge head unit Liquid discharge device

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