Liquid discharge head unit and liquid discharge apparatus

Abstract

The present disclosure provides a liquid ejection head unit and a liquid ejection apparatus. The liquid ejection head unit includes a liquid ejection head and a wiring substrate. The liquid ejection head includes a pressure chamber substrate having a plurality of pressure chambers, a piezoelectric element that applies pressure to the plurality of pressure chambers, and a drive wiring that applies a voltage for driving the piezoelectric element to the piezoelectric element. A detection resistor is provided in the liquid ejection head. The detection resistor is formed of the same material as the piezoelectric element or the drive wiring and is used to detect the temperature of the pressure chamber. A first circuit, a second circuit, and a temperature detection circuit electrically connected to the detection resistor are provided on the wiring substrate. 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.

Description

TECHNICAL FIELD

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

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

[0003] In a liquid ejection head having a piezoelectric element, if a temperature detection circuit is provided outside the liquid ejection head, there is a possibility that the temperature of ink in a pressure chamber cannot be accurately detected. Therefore, there is a desire to configure the temperature detection circuit inside the liquid ejection head. However, if the temperature detection circuit is simply configured on a wiring board inside the liquid ejection head, there is a case where the measurement accuracy of the temperature achieved by the temperature detection circuit decreases.

[0004] Patent Literature 1: Japanese Patent Application Publication No. 2011-104916 SUMMARY

[0005] The present disclosure can be implemented as the following modes.

[0006] According to a first mode of the present disclosure, a liquid ejection head unit is provided. The liquid ejection head unit includes a liquid ejection head provided with a pressure chamber substrate having a plurality of pressure chambers, a piezoelectric element stacked on the pressure chamber substrate and giving pressure to each of the plurality of pressure chambers, and a drive wiring for applying a voltage for driving the piezoelectric element to the piezoelectric element; and a wiring board electrically connected to the liquid ejection head. A detection resistor is provided in the liquid ejection head, the detection resistor being formed of the same material as the piezoelectric element or the drive wiring and being used for detecting the temperature of the pressure chamber. A first circuit, a second circuit different from the first circuit, and a temperature detection circuit electrically connected to the detection resistor are provided on the wiring board. The first circuit, the second circuit, and the temperature detection circuit are provided on the wiring board in such a manner that 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.

[0007] According to a second aspect of this disclosure, a liquid ejection device is provided. This liquid ejection device includes: a liquid ejection head unit as described in the first aspect; and a liquid receiving section for receiving liquid ejected from the liquid ejection head unit. Attached Figure Description

[0008] Figure 1 This is an explanatory diagram showing the general structure of a liquid ejection device.

[0009] Figure 2 An exploded perspective view showing the structure of a liquid ejector head.

[0010] Figure 3 This is an explanatory diagram showing the structure of a liquid ejector head from a top-down perspective.

[0011] Figure 4 To indicate Figure 3 A cross-sectional view at position IV-IV.

[0012] Figure 5 This is a magnified cross-sectional view showing the vicinity of the piezoelectric element.

[0013] Figure 6 To indicate Figure 3 A sectional view at position VI-VI.

[0014] Figure 7 A block diagram illustrating the functional structure of a liquid ejection device.

[0015] Figure 8 This is a block diagram illustrating the functional structure of a liquid ejector unit.

[0016] Figure 9 An explanatory diagram illustrating the placement of a temperature detection circuit in a wiring board.

[0017] Figure 10 This is an explanatory diagram illustrating the configuration relationship between the temperature detection circuit and the first and second circuits in the wiring board through cross-sectional observation.

[0018] Figure 11 This is an explanatory diagram illustrating the configuration relationship between the temperature detection circuit and the first circuit in the wiring board from a top-down view.

[0019] Figure 12 This is an explanatory diagram illustrating the configuration relationship between the temperature detection circuit and the second circuit in the wiring board from a top-down view. Detailed Implementation

[0020] A. First implementation method:

[0021] Figure 1A diagram for illustrating an outline configuration of a liquid ejecting apparatus 500 as a first embodiment of the present disclosure will be described. In the present embodiment, the liquid ejecting apparatus 500 is an inkjet printer that ejects ink as an example of a liquid to a print sheet P to form an image. The liquid ejecting apparatus 500 can also eject a resin film, cloth, or the like as a medium as an object of ejection of the ink instead of the print sheet P. Figure 1 and Figure 1 X, Y, and Z shown in each of the following drawings represent three spatial axes orthogonal to each other. In the present specification, the directions along these axes are also referred to as an X-axis direction, a Y-axis direction, and a Z-axis direction. In the case of determining an orientation, a positive direction is set to "+" and a negative direction is set to "-," and in the direction mark, the direction indicated by the arrow mark of each drawing is set to the + direction and the opposite direction thereof is set to the - direction. In the present embodiment, the Z direction coincides with the vertical direction, the +Z direction represents the vertically downward direction, and the -Z direction represents the vertically upward direction. In addition, in the case where the positive direction and the negative direction are not limited, the configuration of the three X, Y, and Z axes is described.

[0022] As shown in Figure 1 , the liquid ejecting apparatus 500 includes a print head 5, an ink tank 550, a conveyance mechanism 560, a moving mechanism 570, and a control section 540. In the print head 5, a signal or the like for controlling ejection of ink is supplied from the control section 540 via a cable 590. The print head 5 ejects ink supplied from the ink tank 550 at an amount and timing corresponding to the signal supplied from the control section 540. The print head 5 includes the liquid ejecting head unit 51 of the present embodiment and a circuit substrate described later. Although illustration is omitted in Figure 1 , in the present embodiment, the print head 5 includes a plurality of liquid ejecting head units 51. A plurality of liquid ejecting heads 510 are included in each of the liquid ejecting head units 51. The number of the liquid ejecting head units 51 and the liquid ejecting heads 510 is not limited to a plurality and can be one.

[0023] The liquid ejecting head 510 ejects, for example, ink of four colors of black, cyan, magenta, and yellow in the +Z direction from a nozzle to form an image on the print sheet P. The liquid ejecting head 510 moves back and forth in the main scanning direction 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 ejecting head 510 is not limited to four colors and can eject ink of any color such as light cyan, light magenta, white, and the like. The liquid ejecting head 510 has a detection resistor 401 and a heating resistor 601.

[0024] The ink tank 550 functions as a liquid storage portion that stores ink. The ink tank 550 is connected to the print head 5 by a hose 552 made of resin, and ink in the ink tank 550 is supplied to the print head 5 via the hose 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 can be provided.

[0025] The conveyance mechanism 560 conveys the print paper P in the sub-scanning direction. The sub-scanning direction is a direction that intersects the X-axis direction that is the main scanning direction, and in the present embodiment, the +Y direction and the -Y direction. The conveyance mechanism 560 includes a conveyance rod 564 on which three conveyance rollers 562 are mounted, and a conveyance motor 566 that rotationally drives the conveyance rod 564. The print paper P is conveyed in the +Y direction that is the sub-scanning direction by rotationally driving the conveyance rod 564 by the conveyance motor 566. The number of the conveyance rollers 562 is not limited to three, and can be any number. Furthermore, a structure in which a plurality of conveyance mechanisms 560 are provided can be provided.

[0026] The moving mechanism 570 includes a carriage 572, a conveyance belt 574, a moving motor 576, and a pulley 577. The carriage 572 carries the print head 5 in a state in which ink can be ejected. The carriage 572 is fixed to the conveyance belt 574. The conveyance belt 574 is stretched between the moving motor 576 and the pulley 577. The conveyance belt 574 is moved back and forth in the main scanning direction by rotationally driving the moving motor 576. As a result, the carriage 572 fixed to the conveyance belt 574 is also moved back and forth in the main scanning direction.

[0027] The control section 540 controls the entire liquid discharge apparatus 500. The control section 540 controls, for example, the reciprocating movement of the carriage 572 in the main scanning direction, the conveyance movement of the print paper P in the sub-scanning direction, and the ejection movement of the liquid discharge head 510. The control section 540 also functions as a drive control section of the piezoelectric element 300. In the present embodiment, the control section 540 is also capable of heating the liquid in the pressure chamber 12 by the heating resistor 601 provided in the liquid discharge head 510, and capable of detecting the temperature of the pressure chamber 12 by the detection resistor 401 provided in the liquid discharge head 510. The control section 540 detects the temperature of the pressure chamber 12, and adjusts the temperature of the pressure chamber 12 by heating. The control section 540 drives the piezoelectric element 300 by outputting a drive signal based on the detected temperature of the pressure chamber 12 to the liquid discharge head 510, thereby controlling the ejection of the ink to the print paper P. The control section 540 can be constituted by one or a plurality of processing circuits such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array), or one or a plurality of storage circuits such as a semiconductor memory. In the present embodiment, the control section 540 stores the correspondence relation between the resistance value of the detection resistor 401 and the temperature in the storage circuit in advance.

[0028] Reference Signs List Figures 2 to 4 The detailed structure of the liquid discharge head 510 will be described. Figure 2 is an exploded perspective view showing the structure of the liquid discharge head 510. Figure 3 is a view showing the structure of the liquid discharge head 510 in a plan view. In Figure 3 , the structure around the pressure chamber substrate 10 in the liquid discharge head 510 is shown. In Figure 3 , the protective substrate 30 and the housing member 40 are omitted for easy understanding of the technology. Figure 4 is a sectional view showing the IV-IV position of Figure 3 .

[0029] As shown in Figure 2 , the liquid discharge head 510 is provided with the pressure chamber substrate 10, the communication plate 15, the nozzle plate 20, the plastic substrate 45, the protective substrate 30, the housing member 40, and the relay substrate 120, and also has the piezoelectric element 300 shown in Figure 3 and the detection resistor 401 shown in Figure 4The vibration plate 50 is shown. The pressure chamber substrate 10, the communication plate 15, the nozzle plate 20, the plastic substrate 45, the vibration plate 50, the piezoelectric element 300, the protection substrate 30, and the housing member 40 are stacked members, and form the liquid ejecting head 510 by being stacked. In the present disclosure, the direction in which the stacked members that form the liquid ejecting head 510 are stacked is referred to as the "stacking direction".

[0030] 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. 1, the pressure chamber substrate 10 is formed in a rectangular shape in plan view. Figure 3 As shown in FIG. 1, a plurality of pressure chambers 12 are arranged in the pressure chamber substrate 10 in a direction that is predetermined. The direction in which the plurality of pressure chambers 12 are arranged is referred to as the "arrangement direction". The pressure chambers 12 are formed in a rectangular shape in which the length in the X-axis direction is longer than the length in the Y-axis direction when viewed in plan view. The shape of the pressure chambers 12 is not limited to the rectangular shape, and can be a parallelogram shape, a polygonal shape, a circular shape, an elliptical shape, or the like. The elliptical shape referred to herein means a shape in which both end portions in the long side direction are provided in a semicircular shape on the basis of the rectangular shape, and includes a rounded rectangular shape, an elliptical shape, an egg-shaped, and the like.

[0031] In the present embodiment, the plurality of pressure chambers 12 are arranged in two rows each of which has the Y-axis direction as the arrangement direction. In the present embodiment, the arrangement direction of the pressure chambers 12 is the Y-axis direction. Figure 3 In the example shown in FIG. 1, two pressure chamber rows, a first pressure chamber row L1 in which the Y-axis direction is the arrangement direction, and a second pressure chamber row L2 in which the Y-axis direction is the arrangement direction, are formed on the pressure chamber substrate 10. The second pressure chamber row L2 is disposed in a manner that is adjacent to the first pressure chamber row L1 in a direction that intersects the arrangement direction of the first pressure chamber row L1. The direction that intersects the arrangement direction is referred to as the "intersecting direction". In the example shown in FIG. 1, the intersecting direction is the X-axis direction, and the second pressure chamber row L2 is adjacent to the first pressure chamber row L1 in the -X direction. Figure 3 In the example shown in FIG. 1, the intersecting direction is the X-axis direction, and the second pressure chamber row L2 is adjacent to the first pressure chamber row L1 in the -X direction. The arrangement direction refers to the macroscopic arrangement direction of the plurality of pressure chambers 12. For example, a case in which the plurality of pressure chambers 12 are arranged in the Y-axis direction in a so-called staggered arrangement in which the pressure chambers are disposed in a manner that is offset from each other in the intersecting direction at every other pressure chamber is also included in the arrangement direction.

[0032] The plurality of pressure chambers 12 belonging to the first pressure chamber row L1 and the plurality of pressure chambers 12 belonging to the second pressure chamber row L2 are formed in a manner that the positions in the respective arrangement directions coincide with each other, and are disposed in a manner that is adjacent to each other in the intersecting direction. In each pressure chamber row, the pressure chambers 12 that are adjacent to each other in the Y-axis direction are divided by the partition walls 11 as described later. Figure 6

[0033] As shown in FIG. 1, the plurality of pressure chambers 12 are arranged in the Y-axis direction in a manner that is offset from each other in the X-axis direction at every other pressure chamber. In the example shown in FIG. 1, the pressure chambers 12 are arranged in the Y-axis direction in a manner that is offset from each other in the X-axis direction at every other pressure chamber in the first pressure chamber row L1 and the second pressure chamber row L2. Figure 2 ​As shown, a connecting plate 15, a nozzle plate 20, and a malleable substrate 45 are sequentially stacked on the +Z direction side of the pressure chamber substrate 10. The connecting plate 15 is, for example, a flat plate made of a silicon substrate, glass substrate, SOI substrate, various ceramic substrates, metal substrates, etc. Examples of metal substrates include stainless steel substrates. Figure 4 As shown, a nozzle communication channel 16, a first manifold section 17, a second manifold section 18, and a supply communication channel 19 are provided on the communication plate 15. The communication plate 15 is preferably made of a material with a thermal expansion coefficient approximately the same as that of the pressure chamber substrate 10. Therefore, when the temperature of the pressure chamber substrate 10 and the communication plate 15 changes, warping of the pressure chamber substrate 10 and the communication plate 15 due to differences in thermal expansion coefficients can be suppressed.

[0034] like Figure 4 As shown, the nozzle communication channel 16 is a flow channel connecting the pressure chamber 12 and the nozzle 21. The first manifold section 17 and the second manifold section 18 function as part of a manifold 100, which becomes a common liquid chamber connected to the plurality of pressure chambers 12. The first manifold section 17 is provided such that it penetrates the connecting plate 15 in the Z-axis direction. Furthermore, as... Figure 4 As shown, the second manifold 18 does not penetrate the connecting plate 15 in the Z-axis direction, but is disposed on the surface of the connecting plate 15 in the +Z direction.

[0035] The supply communication channel 19 is a flow channel that communicates with one end of the pressure chamber 12 in the X-axis direction. There are multiple supply communication channels 19, which are arranged along the Y-axis direction, i.e., the arrangement direction, and are individually provided for each of the pressure chambers 12. The supply communication channel 19 communicates the second manifold 18 and each pressure chamber 12, thereby supplying ink in the manifold 100 to each pressure chamber 12.

[0036] The nozzle plate 20 is disposed on the opposite side of the pressure chamber substrate 10, i.e., on the +Z direction side of the connecting plate 15, sandwiching the connecting plate 15. The material of the nozzle plate 20 is not particularly limited; for example, silicon substrates, glass substrates, SOI substrates, various ceramic substrates, and metal substrates can be used. Examples of metal substrates include stainless steel substrates. Organic materials such as polyimide resin can also be used as the material of the nozzle plate 20. However, it is preferable that the nozzle plate 20 is made of a material with approximately the same coefficient of thermal expansion as the connecting plate 15. Therefore, when the temperature of the nozzle plate 20 and the connecting plate 15 changes, warping of the nozzle plate 20 and the connecting plate 15 due to differences in their coefficients of thermal expansion can be suppressed.

[0037] 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 in the arrangement direction of the pressure chambers 12, that is, the Y-axis direction. In the nozzle plate 20, nozzle rows in which the plurality of nozzles 21 are arranged are provided in two rows. The two nozzle rows correspond to the first pressure chamber row L1 and the second pressure chamber row L2, respectively.

[0038] As Figure 4 indicated, the plastic substrate 45 is provided on the side opposite to the nozzle plate 20, that is, the +Z direction side of the face of the pressure chamber substrate 10, together with the communication plate 15. The plastic substrate 45 is provided at the periphery of 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 plastic substrate 45 has a sealing film 46 composed of a thin film having flexibility and a fixed substrate 47 composed of a hard material such as metal. As Figure 4 indicated, the region of the fixed substrate 47 opposite to the manifold 100 becomes an opening portion 48 completely removed in the thickness direction. Therefore, one face of the manifold 100 becomes a plastic portion 49 sealed only with the sealing film 46.

[0039] As Figure 4 indicated, on the side opposite to the nozzle plate 20 and the like, that is, the -Z direction side of the face of the pressure chamber substrate 10, sandwiching the pressure chamber substrate 10, a vibration plate 50 and a piezoelectric element 300 are laminated. The piezoelectric element 300 causes the vibration plate 50 to be flexibly deformed, thereby causing the ink in the pressure chamber 12 to be subjected to pressure variation. In Figure 4 , the structure of the piezoelectric element 300 is simplified for easy understanding of the technology. The vibration plate 50 is provided on the +Z direction side of the piezoelectric element 300, and the pressure chamber substrate 10 is provided on the +Z direction side of the vibration plate 50.

[0040] As Figure 4 indicated, on the -Z direction side of the face of the pressure chamber substrate 10, a protection substrate 30 having substantially the same size as the pressure chamber substrate 10 is also joined by an adhesive or the like. The protection substrate 30 has a holding portion 31 as a space for protecting the piezoelectric element 300. The holding portion 31 is provided for each row of the piezoelectric elements 300 arranged in the arrangement direction, and in the present embodiment, the holding portions 31 are formed in two rows in parallel in the X-axis direction. Further, in the protection substrate 30, a through hole 32 penetrating in the Z-axis direction is provided between the two holding portions 31 arranged side by side in the X-axis direction.

[0041] As Figure 4As shown, a housing component 40 is fixed on the protective base plate 30. The housing component 40, together with the connecting plate 15, forms a manifold 100 connecting the plurality of pressure chambers 12. When viewed from above, the housing component 40 has a substantially the same shape as the connecting plate 15 and is joined together across the connecting plate 15 and the protective base plate 30.

[0042] The housing component 40 has a receiving portion 41, a supply port 44, a third manifold portion 42, and a connection port 43. The receiving portion 41 is a space with a depth sufficient to receive the pressure chamber substrate 10 and the protective substrate 30. The third manifold portion 42 is a space formed in the housing component 40 at two outer sides in the X-axis direction of the receiving portion 41. By connecting the third manifold portion 42 with the first manifold portion 17 and the second manifold portion 18 provided on the connecting plate 15, a manifold 100 is formed. The manifold 100 has a shape that is a continuous strip spanning the Y-axis direction. The supply port 44 communicates with the manifold 100 and supplies ink to each manifold 100. The connection port 43 is a through hole communicating with the through hole 32 of the protective substrate 30, and a relay substrate 120 is inserted through it.

[0043] In the liquid ejector head 510 of this embodiment, liquid is received from the supply port 44 from... Figure 1 After the ink tank 550 is supplied with ink and its internal flow channels are filled with ink from the manifold 100 to the nozzle 21, a voltage based on a drive signal is applied to each piezoelectric element 300 corresponding to the plurality of pressure chambers 12. As a result, the vibrating plate 50 and the piezoelectric elements 300 flex and deform together, causing the pressure in each pressure chamber 12 to increase, thereby ejecting ink droplets from each nozzle 21.

[0044] use Figures 3 to 6 The structure of the pressure chamber substrate 10 in the -Z direction will be described. Figure 5 This is a magnified cross-sectional view showing the area around the piezoelectric element 300. Figure 6 To indicate Figure 3 A cross-sectional view at position VI-VI. In addition to the vibrating plate 50 and the piezoelectric element 300, the liquid ejector head 510 on the -Z direction side of the pressure chamber substrate 10 also has a separate lead electrode 91, a common lead electrode 92, a measuring lead electrode 93, a heating lead electrode 94, a detection resistor 401, and a heating resistor 601.

[0045] like Figure 5 and Figure 6As shown, the diaphragm 50 is provided with an elastic film 55 composed of silicon oxide provided on the side of the pressure chamber substrate 10, and an insulator film 56 composed of a zirconium oxide film provided on the elastic film 55. The flow passage of the pressure chamber 12 and the like formed on the pressure chamber substrate 10 is formed by anisotropic etching from the side of the surface of the pressure chamber substrate 10 in the +Z direction, and the surface of the flow passage of the pressure chamber 12 and the like in the -Z direction is composed of the elastic film 55. The diaphragm 50 can be composed of either one of the elastic film 55 and the insulator film 56, for example, and can include other films other than the elastic film 55 and the insulator film 56. As a material of the other films, silicon, silicon nitride, and the like can be listed.

[0046] The piezoelectric element 300 applies pressure to the pressure chamber 12. As shown in FIG. 1, the piezoelectric element 300 is provided on the side of the pressure chamber 12 in the -Z direction. Figure 5 Figure 6 As shown, 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 sequentially stacked from the side of the surface of the piezoelectric element 300 in the +Z direction toward the side of the surface of the piezoelectric element 300 in the -Z direction. Figure 5 Figure 6 The piezoelectric body 70 is provided between the first electrode 60 and the second electrode 80 in the stacking direction in which the first electrode 60, the second electrode 80, and the piezoelectric body 70 are stacked, that is, in the Z-axis direction.

[0047] 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. In the first electrode 60, a different drive voltage is supplied in accordance with the amount of ink to be ejected, and in the second electrode 80, a fixed reference voltage signal is supplied regardless of the amount of ink to be ejected. The amount of ink to be ejected is the amount of change in volume required for the pressure chamber 12. When a potential difference is generated between the first electrode 60 and the second electrode 80 by driving the piezoelectric element 300, the piezoelectric body 70 is deformed. By the deformation of the piezoelectric body 70, the diaphragm 50 is deformed or vibrated to change the volume of the pressure chamber 12. By the change in the volume of the pressure chamber 12, pressure is applied to the ink accommodated in the pressure chamber 12 to cause the ink to be ejected from the nozzle 21 via the nozzle communication passage 16.

[0048] As shown in FIG. 1, the piezoelectric element 300 is provided on the side of the pressure chamber 12 in the -Z direction. Figure 5 ​​As shown, a portion of the piezoelectric element 300 in which a piezoelectric strain is generated in the piezoelectric body 70 when a voltage is applied between the first electrode 60 and the second electrode 80 is referred to as an active portion 310. In contrast, a portion in which a piezoelectric strain is not generated in the piezoelectric body 70 is referred to as an inactive portion 320. That is, in the piezoelectric element 300, a portion of the piezoelectric body 70 that is sandwiched by the first electrode 60 and the second electrode 80 is the active portion 310, and a portion of the piezoelectric body 70 that is not sandwiched by the first electrode 60 and the second electrode 80 is the inactive portion 320. When the piezoelectric element 300 is caused to drive, a portion that actually undergoes displacement in the Z-axis direction is referred to as a flexible portion, and a portion that does not undergo displacement in the Z direction is referred to as a non-flexible portion. That is, in the piezoelectric element 300, a portion that opposes the pressure chamber 12 in the Z-axis direction becomes the flexible portion, and an outer portion of the pressure chamber 12 becomes the non-flexible portion. The active portion 310 is also referred to as a powered portion, and the inactive portion 320 is also referred to as an unpowered portion.

[0049] The first electrode 60 is formed of a conductive material such as a metal such as platinum (Pt), iridium (Ir), gold (Au), titanium (Ti), a conductive metal oxide such as indium tin oxide (ITO), or the like. The first electrode 60 can also be formed by laminating a plurality of materials such as platinum (Pt), iridium (Ir), gold (Au), titanium (Ti), or the like. In the present embodiment, platinum (Pt) is used as the first electrode 60.

[0050] As shown, the first electrode 60 is a separate electrode that is separately provided with respect to the 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 at an inner side compared to both ends of the pressure chamber 12 in the Y-axis direction. As shown, the end portion 60a of the first electrode 60 in the +X direction and the end portion 60b in the -X direction are respectively disposed at the outer side of the pressure chamber 12. For example, in the first pressure chamber row, the end portion 60a of the first electrode 60 is disposed at a position that is on the +X direction side compared to the end portion 12a of the pressure chamber 12 in the +X direction. The end portion 60b of the first electrode 60 is disposed at a position that is on the -X direction side compared to the end portion 12b of the pressure chamber 12 in the -X direction. Figure 3 Figure 5 As shown, the end portion 60a of the first electrode 60 in the +X direction and the end portion 60b in the -X direction are respectively disposed at the outer side of the pressure chamber 12. For example, in the first pressure chamber row, the end portion 60a of the first electrode 60 is disposed at a position that is on the +X direction side compared to the end portion 12a of the pressure chamber 12 in the +X direction. The end portion 60b of the first electrode 60 is disposed at a position that is on the -X direction side compared to the end portion 12b of the pressure chamber 12 in the -X direction.

[0051] As shown, the end portion 60a of the first electrode 60 in the +X direction and the end portion 60b in the -X direction are respectively disposed at the outer side of the pressure chamber 12. For example, in the first pressure chamber row, the end portion 60a of the first electrode 60 is disposed at a position that is on the +X direction side compared to the end portion 12a of the pressure chamber 12 in the +X direction. The end portion 60b of the first electrode 60 is disposed at a position that is on the -X direction side compared to the end portion 12b of the pressure chamber 12 in the -X direction. Figure 3 ​As shown, the piezoelectric body 70 has a predetermined width in the X-axis direction, and is disposed in a manner extending in the arrangement direction of the pressure chamber 12, that is, the Y-axis direction. As the piezoelectric body 70, a crystal film of a perovskite structure composed of a ferroelectric ceramic material exhibiting an electromechanical conversion action, so-called perovskite crystal, formed on the first electrode 60 can be cited. As the material of the piezoelectric body 70, for example, a ferroelectric piezoelectric material such as zirconate titanate (PZT), or a substance to which a metal oxide such as niobium oxide, nickel oxide, or magnesium oxide is added, or the like 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 niobium magnesium zirconate titanate (Pb(Zr,Ti)(Mg,Nb)O3), or the like can be used. In the present embodiment, lead zirconate titanate (PZT) is used as the piezoelectric body 70.

[0052] As the material of the piezoelectric body 70, not only a lead-containing lead-based piezoelectric material, but also a non-lead-containing non-lead-based piezoelectric material can be used. As the non-lead-based piezoelectric material, for example, 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 niobate tantalate ((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 manganese oxide (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] (x is 0.1 to 0.9), abbreviated as "BFO-BT"), a substance to which a metal such as manganese, cobalt, or chromium is added ((1-x)[Bi(Fe1-yMy)O3]-x[BaTiO3] (M is Mn, Co, or Cr)), or the like can be cited. 3 ], abbreviated as "BFO-BT"), a substance to which a metal such as manganese, cobalt, or chromium is added ((1-x)[Bi(Fe1-yMy)O3]-x[BaTiO3] (M is Mn, Co, or Cr)), or the like can be cited.

[0053] The thickness of the piezoelectric body 70 is formed, for example, to be about 1000 nm to 4000 nm. As the thickness of the piezoelectric body 70, for example, a thickness of 1000 nm to 4000 nm can be used. The thickness of the piezoelectric body 70 is not limited to this range, and can be appropriately set according to the intended use. Figure 5As shown, the width of the piezoelectric body 70 in the X-axis direction is longer than its length in the X-axis direction, which is the long side of the pressure chamber 12. Therefore, the piezoelectric body 70 extends to the outer side of the pressure chamber 12 on both sides in the X-axis direction. In this way, by extending the piezoelectric body 70 to the outer side of the pressure chamber 12 in the X-axis direction, the strength of the vibrating plate 50 is improved. Therefore, when the active part 310 is driven to displace the piezoelectric element 300, it is possible to suppress the generation of cracks or other defects in the vibrating plate 50 or the piezoelectric element 300.

[0054] like Figure 5 As shown, the +X direction end 70a of the piezoelectric body 70 is located on the +X direction side, which is further outward than 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, which is further inward than the end 60b of the first electrode 60, so that the end 60b of the first electrode 60 is not covered by the piezoelectric body 70.

[0055] like Figure 3 and Figure 6 As shown, a groove portion 71 is formed on the piezoelectric body 70, which is thinner than other regions. Figure 6 As shown, groove portions 71 are provided at positions corresponding to each partition wall 11. Groove portions 71 are formed by completely removing the piezoelectric element 70 in the Z-axis direction. On the bottom surface of the groove portion 71, the piezoelectric element 70 may also be formed to be thinner than other portions. The width of the groove portion 71 in the Y-axis direction is formed to be the same as the width of the partition wall 11 in the Y-axis direction, or it is formed to be wider than the width of the partition wall 11 in the Y-axis direction. Figure 3 As shown, the groove portion 71 has a generally rectangular shape when viewed from above. By providing the groove portion 71 on the piezoelectric element 70, the rigidity of the portion of the vibrating plate 50 that faces the end of the pressure chamber 12 in the Y-axis direction, the so-called arm portion of the vibrating plate 50, is suppressed, thus enabling better displacement of the piezoelectric element 300. The groove portion 71 is not limited to a rectangular shape; it can be a polygonal shape with pentagonal or larger shapes, or it can be a circular or elliptical shape, etc.

[0056] like Figure 5 and Figure 6 As shown, the second electrode 80 is disposed on the side opposite to the first electrode 60, that is, on the -Z direction side of the piezoelectric body 70, sandwiching the piezoelectric body 70. Figure 3As shown, the second electrode 80 is provided in a manner shared with respect to the multiple pressure chambers 12, and is a common electrode shared by the multiple active parts 310. Although the material of the second electrode 80 is not particularly limited, similar to the first electrode 60, conductive materials such as metals like platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti), or conductive metal oxides such as indium tin oxide (ITO) are used. Alternatively, it can be formed by stacking multiple materials such as platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti). In this embodiment, iridium (Ir) is used as the second electrode 80.

[0057] like Figure 3 As shown, the second electrode 80 has a predetermined width in the X-axis direction and is arranged to extend along the arrangement direction of the pressure chamber 12, i.e., the Y-axis direction. Figure 6 As shown, the second electrode 80 is also disposed on the side of the groove portion 71 of the piezoelectric body 70 and on the insulating film 56, which serves as the bottom surface of the groove portion 71.

[0058] like Figure 5 As shown, the +X direction end 80a of the second electrode 80 is positioned outward compared to the end 60a of the first electrode 60 covered by the piezoelectric body 70, i.e., on the +X direction side. The end 80a of the second electrode 80 is located outward compared to the end 12a of the pressure chamber 12, and also outward compared to the end 60a of the first electrode 60. In this embodiment, the end 80a of the second electrode 80 is substantially aligned with the end 70a of the piezoelectric body 70 in the X-axis direction. As a result, at the end 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 60a of the first electrode 60.

[0059] like Figure 5 As shown, the -X direction end 80b of the second electrode 80 is positioned on the -X direction side, which is outer compared to the -X direction end 12b of the pressure chamber 12, and on the +X direction side, which is inner compared to the end 70b of the piezoelectric body 70. The end 70b of the piezoelectric body 70 is located on the inner side, which is on the +X direction side, compared to the end 60b of the first electrode 60. Therefore, the end 80b of the second electrode 80 is located on the piezoelectric body 70, which is on the +X direction side, compared to the end 60b of the first electrode 60. On the -X direction side of the end 80b of the second electrode 80, there is a portion where the surface of the piezoelectric body 70 is exposed. Thus, since the end 80b of the second electrode 80 is positioned on the +X direction side compared to the end 70b of the piezoelectric body 70 and the end 60b of the first electrode 60, the boundary between the active part 310 and the inactive part 320 is defined by the end 80b of the second electrode 80 at the end of the active part 310 in the -X direction.

[0060] A wiring portion 85 is provided on the outer side of the end 80b of the second electrode 80. Although the wiring portion 85 is in the same layer as the second electrode 80, it is not electrically continuous with the second electrode 80. The wiring portion 85 is formed from near the end 70b of the piezoelectric body 70 to the end 60b of the first electrode 60, spaced apart from the end 80b of the second electrode 80. The wiring portion 85 is provided for each active part 310. That is, multiple 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. This simplifies the manufacturing process of the wiring portion 85 and reduces costs. However, the wiring portion 85 may also be formed in a different layer than the second electrode 80.

[0061] like Figure 5 As shown, a separate lead electrode 91 is connected to the first electrode 60, which is a separate electrode, and a common lead electrode 92, which serves as a common electrode for driving, is electrically connected to the second electrode 80, which is a common electrode. The separate lead electrode 91 and the common lead electrode 92 function as drive wiring for applying a voltage to the piezoelectric element 70 to drive the piezoelectric element 70. In this embodiment, the power supply circuit for supplying power to the piezoelectric element 70 via the drive wiring and the power supply circuit for supplying power to the heating resistor 601 and the sensing resistor 401 are set to be different circuits.

[0062] like Figure 3 and Figure 4 As shown, the individual lead electrode 91 and the common lead electrode 92 extend into the through-hole 32 formed on the protective substrate 30 and are electrically connected to the relay substrate 120 within the through-hole 32. The relay substrate 120 has multiple wirings formed for connection to the control substrate 580 and a power circuit (not shown). In this embodiment, the relay substrate 120 is, for example, constructed from a flexible substrate (FPC). Alternatively, it may be constructed from any flexible substrate such as an FFC (Flexible Flat Cable) instead of an FPC.

[0063] An integrated circuit 121 with switching elements is mounted on the relay substrate 120. A signal for driving the piezoelectric element 300, transmitted via the relay substrate 120, is input into the integrated circuit 121. Based on the input signal, the integrated circuit 121 controls the timing of the supply of the signal for driving the piezoelectric element 300 to the first electrode 60. Thus, the timing of driving the piezoelectric element 300 and the amount of driving the piezoelectric element 300 are controlled.

[0064] The individual lead electrode 91 and the common lead electrode 92 are made of conductive materials, such as gold (Au), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), platinum (Pt), and aluminum (Al). In this embodiment, gold (Au) is used as both the individual lead electrode 91 and the common lead electrode 92. Furthermore, the individual lead electrode 91 and the common lead electrode 92 may also have a bonding layer that improves adhesion to the first electrode 60, the second electrode 80, or the vibrating plate 50.

[0065] Although the individual lead electrode 91 and the common lead electrode 92 are formed on the same layer, they are formed in a non-electrically continuous manner. Therefore, compared to forming the individual lead electrode 91 and the common lead electrode 92 separately, the manufacturing process can be simplified, thereby reducing costs. The individual lead electrode 91 and the common lead electrode 92 can also be formed on different layers.

[0066] Individual lead electrodes 91 are provided for each active portion 310, i.e., each first electrode 60. For example... Figure 5 As shown, for example, a single lead electrode 91 is connected to the vicinity of the end 60b of the first electrode 60 via a wiring portion 85 in the first pressure chamber row L1, and is led out in the -X direction to the vibrating plate 50.

[0067] like Figure 3 As shown, for example in the first pressure chamber row L1, the common lead electrode 92 is led out from the second electrode 80 in the -X direction at both ends in the Y-axis direction until it reaches the vibrating plate 50. The common lead electrode 92 has an extension portion 92a and an extension portion 92b. Figure 5 As shown, for example in the first pressure chamber row L1, the extension portion 92a is provided along the Y-axis direction in the region corresponding to the end 12a of the pressure chamber 12, and the extension portion 92b is provided along the Y-axis direction in the region corresponding to the end 12b of the pressure chamber 12. The extension portions 92a and 92b are provided continuously across the Y-axis direction relative to the plurality of active portions 310.

[0068] The extension portions 92a and 92b extend from the inside of the pressure chamber 12 to the outside of the pressure chamber 12 in the X-axis direction. In this 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, and the extension portions 92a and 92b extend from the active portion 310 to the outside of the pressure chamber 12.

[0069] like Figure 3 as well asFigure 5 As shown, a heating resistor 601 is provided on the Z-direction side of the vibrating plate 50, specifically on the Z-direction side of the vibrating plate 50. Specifically, the heating resistor 601 is located between the vibrating plate 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 for heating the pressure chamber 12. In this embodiment, the heating resistor 601 utilizes resistance heating generated by allowing current to flow through the resistance of a metal or semiconductor, thereby heating the liquid within the pressure chamber 12.

[0070] Various heating elements can be used as the material for the heating resistor 601. Examples of heating elements include metallic heating elements such as gold (Au), platinum (Pt), iridium (Ir), aluminum (Al), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), and chromium (Cr). The heating resistor 601 can also be formed from non-metallic heating elements such as silicon carbide, molybdenum silicide, or carbon. In this embodiment, the heating resistor 601 is disposed at the same position as the first electrode 60 in the stacking direction, i.e., on the same layer as the first electrode 60, and is formed in a manner that is not electrically continuous with the first electrode 60. The material of the heating resistor 601 is platinum (Pt), the same as that of the first electrode 60. Therefore, compared to forming the heating resistor 601 and the first electrode 60 separately, the manufacturing process can be simplified, thereby reducing costs. The heating resistor 601 can also be formed on a different layer than the first electrode 60.

[0071] like Figure 3 As shown, a portion of the heating resistor 601 is formed in a straight line along the first pressure chamber row L1 and is disposed outside the liquid ejector head 510 in the +X direction, i.e., in the intersecting direction, compared to the pressure chamber 12 included in the first pressure chamber row L1. In this embodiment, the remaining portion of the heating resistor 601 is formed in a straight line along the second pressure chamber row L2 and is disposed outside the liquid ejector head 510 in the -X direction, i.e., in the intersecting direction, compared to the pressure chamber 12 included in the second pressure chamber row L2. Thus, in this embodiment, the heating resistor 601 is continuously formed outside the liquid ejector head 510 in a manner that surrounds both the first pressure chamber row L1 and the second pressure chamber row L2.

[0072] exist Figure 3The diagram 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 portion connecting 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. Thus, the heating resistor 601 is electrically connected to the relay substrate 120, and the control unit 540 can apply a heating voltage to the heating resistor 601 to cause resistive heating. Although in Figure 3 In the example, the heating resistor 601 is formed in a straight line, but it is not limited to this. For example, it can also be formed as a so-called meandering pattern that goes back and forth multiple times near the first pressure chamber row L1 and the second pressure chamber row L2.

[0073] In this embodiment, the heating lead electrode 94 is formed on the same layer as the individual lead electrode 91 and the shared lead electrode 92, and is formed in a non-electrically continuous manner. The material of the heating lead electrode 94 is a conductive material, such as gold (Au), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), platinum (Pt), aluminum (Al), etc. In this 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 shared lead electrode 92. The heating lead electrode 94 may also have a bonding layer that improves the adhesion to the heating resistor 601 or the vibrating plate 50.

[0074] like Figure 5 As shown, in this embodiment, a detection resistor 401 is also provided on the surface of the vibrating plate 50 in the -Z direction. Specifically, the detection resistor 401 is located between the vibrating plate 50 and the piezoelectric element 70 in the Z-axis direction and is covered by the piezoelectric element 70. That is, the detection resistor 401 is disposed at the same position as the piezoelectric element 300, i.e., on the same layer as the piezoelectric element 300, in the stacking direction of the piezoelectric element 300 relative 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 this embodiment, the temperature of the detection resistor 401 is detected by utilizing the characteristic that the resistance value of the metal or semiconductor changes with temperature. The control unit 540 measures the resistance value of the detection resistor 401 when the piezoelectric element 300 is driven, and detects the temperature of the pressure chamber 12 based on the correspondence between the resistance value of the detection resistor 401 and the temperature.

[0075] The material of the detection resistor 401 is a material having a temperature-dependent resistance value, and, for example, gold (Au), platinum (Pt), iridium (Ir), aluminum (Al), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), or the like can be used. Among these, platinum (Pt) is preferably used as the material of the detection resistor 401 from the viewpoint that the change in resistance value caused by temperature is large and the stability and accuracy are high. The resistance value is one example of the measurement value of the detection resistor that is measured. In the present embodiment, the detection resistor 401 is provided in the same layer as the heating resistor 601 and the first electrode 60 in the stacking direction, and is formed so as not to be electrically continuous with the heating resistor 601 and the first electrode 60. The material of the detection resistor 401 is platinum (Pt) that is the same as the heating resistor 601 and the first electrode 60. Thus, compared to a 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 to reduce the cost. The detection resistor 401 can also be formed in a layer different from the heating resistor 601 and the first electrode 60.

[0076] As shown in FIG. 6, in the present embodiment, the detection resistor 401 is continuously formed so as to surround the periphery of the first pressure chamber row L1 and the second pressure chamber row L2. In the present embodiment, the detection resistor 401 is formed so as to surround the periphery of the first pressure chamber row L1 and the second pressure chamber row L2. Thus, the temperature of the pressure chamber 12 can be detected with high accuracy. Figure 3 As shown in FIG. 6, in the present embodiment, the detection resistor 401 is continuously formed so as to surround the periphery of the first pressure chamber row L1 and the second pressure chamber row L2. In the present embodiment, the detection resistor 401 is formed so as to surround the periphery of the first pressure chamber row L1 and the second pressure chamber row L2. Thus, the temperature of the pressure chamber 12 can be detected with high accuracy. Figure 3 As shown in FIG. 6, in the present embodiment, the detection resistor 401 is continuously formed so as to surround the periphery of the first pressure chamber row L1 and the second pressure chamber row L2. In the present embodiment, the detection resistor 401 is formed so as to surround the periphery of the first pressure chamber row L1 and the second pressure chamber row L2. Thus, the temperature of the pressure chamber 12 can be detected with high accuracy. Figure 3 In the example of FIG. 6, although the detection resistor 401 is formed in a straight line shape, it is not limited thereto, and, for example, can be formed in a so-called meandering pattern that goes back and forth several times in the vicinity of the first pressure chamber row L1 and the second pressure chamber row L2. By being configured in this way, the detection accuracy of the temperature of the pressure chamber 12 can be improved.

[0077] In this embodiment, the measurement lead electrode 93 is formed on the same layer as the individual lead electrode 91 and the common lead electrode 92, and is formed in a manner that is not electrically continuous. The material of the measurement lead electrode 93 is a material having electrical conductivity, such as gold (Au), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), platinum (Pt), aluminum (Al), or the like. In this embodiment, gold (Au) is used as the measurement lead electrode 93. The material of the measurement lead electrode 93 is the same material as the individual lead electrode 91 and the common lead electrode 92. The measurement lead electrode 93 can also have a tack layer that improves adhesion to the detection resistor 401 or the vibration plate 50.

[0078] As Figure 3 shown, a portion of the detection resistor 401 is formed in a linear shape along the arrangement direction of the pressure chambers 12 in the first pressure chamber column L1, and is disposed on the +X direction side, that is, the outside of the liquid ejection head 510 in the cross direction, compared to the pressure chambers 12 included in the first pressure chamber column L1. In this embodiment, the other portion of the detection resistor 401 is formed in a linear shape along the arrangement direction of the pressure chambers 12 in the second pressure chamber column L2, and is disposed on the -X direction side, that is, the outside of the liquid ejection head 510 in the cross direction, compared to the pressure chambers 12 included in the second pressure chamber column L2. In this way, in this embodiment, the detection resistor 401 is continuously formed on the outside of the liquid ejection head 510 in a manner that surrounds the periphery of the first pressure chamber column L1 and the second pressure chamber column L2. The detection resistor 401 is disposed on the inner side in the liquid ejection head 510 compared to the heating resistor 601. By disposing the detection resistor 401 at a position close to the pressure chambers 12, it is possible to improve the detection accuracy of the temperature of the pressure chambers 12 achieved by the detection resistor 401.

[0079] Referring Figures 7 to 9 to the functional structure and the disposition method of the circuit board included in the liquid ejection apparatus 500 of this embodiment will be described. Figure 7 is a block diagram showing the functional structure of the liquid ejection apparatus 500. As Figure 7 shown, the liquid ejection apparatus 500 includes a print head 5 and a control board 580. The control board 580 is a board including a hardware logic circuit that is used to achieve the functions of the control section 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 within the main body of the liquid ejection apparatus 500. In this embodiment, the control board 580 is made separate from the wiring board 530, thereby reducing or suppressing heat transfer from each electronic circuit of the control board 580 to the temperature detection circuit 400. As Figure 7As shown, the print head 5 has a plurality of liquid discharge head units 51 each having a plurality of liquid discharge heads 510. In addition, in the liquid discharge head units 51, the liquid discharge heads 510 are arranged in a row in the direction in which the liquid discharge heads 510 are arrayed in the liquid discharge head unit 51. Figure 7 Hereafter, illustration of the ink tank 550, the conveyance mechanism 560, and the moving mechanism 570 is omitted.

[0080] The control substrate 580 and the print head 5 are communicably connected together by a cable 590. In the present embodiment, a terminal group provided on the control substrate 580 and a terminal group provided on the branch wiring substrate 520 included in the print head 5 are electrically connected by the cable 590. The cable 590 uses various cables corresponding to the form of the signals to be transmitted, such as a flexible flat cable (FFC), a coaxial cable, or the like. The cable 590 can also be an optical communication cable that transmits optical signals.

[0081] The control substrate 580 generates signals for controlling the respective structures of the liquid discharge apparatus 500 on the basis of image data input from a host computer or the like provided outside the liquid discharge apparatus 500, and outputs the signals to the corresponding structures. The control substrate 580 has a liquid discharge apparatus 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. In addition, the control substrate 580 is not limited to being composed of one substrate, and can be composed of a plurality of substrates. For example, it can be a structure in which at least a part of the plurality of circuits mounted on the control substrate 580, including the liquid discharge apparatus 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, which the control substrate 580 has, are mounted on different substrates, and are electrically connected using a connector, a cable, or the like, not shown.

[0082] A commercial power supply is input to the power supply circuit 584. The power supply circuit 584 converts the input commercial power supply to a direct-current voltage of, for example, 42 V, and outputs the same. The direct-current voltage output from the power supply circuit 584 is input to the voltage detection circuit 585, and is also used as a power supply voltage of the respective structures of the liquid discharge apparatus 500. Here, in the respective structures of the liquid discharge apparatus 500, the output direct-current voltage can be used as it is as a power supply voltage and a drive voltage, or a voltage signal converted to various voltage values of 3.3 V, 5 V, 7.5 V, or the like by a voltage conversion circuit, not shown, can be used as a power supply voltage and a drive voltage.

[0083] The voltage detection circuit 585 detects whether or not the power supply voltage such as commercial power is being supplied to the liquid discharge apparatus 500, based on the voltage value of the direct current voltage output from the power supply circuit 584. Then, the voltage detection circuit 585 generates a voltage detection signal of a logic level corresponding to the detection result, and outputs to the time measurement circuit 583.

[0084] The time measurement circuit 583 judges whether or not the power supply voltage is being supplied to the liquid discharge apparatus 500, based on the voltage detection signal input. The time measurement circuit 583 generates elapsed time information and outputs to the liquid discharge apparatus control circuit 581, in a case where it is judged based on the voltage detection signal that the power supply voltage is being supplied to the liquid discharge apparatus 500.

[0085] The liquid discharge apparatus control circuit 581 generates various signals for controlling the operation of each portion of the liquid discharge apparatus 500, and outputs to each portion possessed by the liquid discharge apparatus 500. In the liquid discharge apparatus control circuit 581, the print head operation information signal including the driving state of the print head 5 is input from the print head control circuit 586.

[0086] The print head control circuit 586 generates a drive data signal for driving the plurality of piezoelectric elements 300 possessed by the print head 5, a print data signal SI for controlling the timing of supplying the drive signal COM to the piezoelectric elements 300, a clock signal SCK, a latch signal LAT, a switching signal CH, and a switching signal SW. The print data signal SI, the clock signal SCK, the latch signal LAT, the switching 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. In addition, the print head control circuit 586 generates and outputs the print data signal SI and the switching signal SW corresponding to each of the plurality of liquid discharge heads 510 possessed by the print head 5. The print head control circuit 586 generates a drive data signal that specifies the waveform of the drive signal COM for driving the piezoelectric elements 300, and outputs to the drive signal output circuit 587.

[0087] After converting the input drive data signal to an analog signal, the drive signal output circuit 587 performs D-level amplification on the converted analog signal based on a DC voltage to generate a drive signal COM. In other words, the drive data signal is a digital signal that defines the waveform of the drive signal COM. The drive signal output circuit 587 performs D-level amplification on the waveform defined by the drive data signal based on a DC voltage to generate a drive signal COM with a sufficiently large maximum voltage value for driving the piezoelectric element 300, and whose voltage value changes. The drive signal COM is input to the print head 5 via cable 590. The drive data signal can be any signal capable of defining the waveform of the drive signal COM, and can be, for example, an analog signal. The drive signal output circuit 587 can amplify the waveform defined by the drive data signal, and can be configured to include an A-level amplification circuit, a B-level amplification circuit, or an AB-level amplification circuit.

[0088] The printhead control circuit 586 outputs a memory control signal for controlling the memory of the branch line board 520, which will be described later. Memory control includes processes such as reading information stored in the memory and writing information to the memory. When the memory control signal is output, a storage data signal corresponding to the information read from the memory is input to the printhead control circuit 586.

[0089] like Figure 7 As shown, the printhead 5 has a branch line substrate 520 and a plurality of liquid ejection head units 51. The branch line substrate 520 is electrically connected to each of the plurality of liquid ejection head units 51 via a cable 522. The plurality of liquid ejection head units 51 of the printhead 5 have the same structure.

[0090] In the sub-controller board 520, drive signal COM, printing data signal SI, clock signal SCK, latch signal LAT, exchange signal CH, and switching signal SW are input from the control board 580 via cable 590. After being transmitted to the sub-controller board 520, drive signal COM, printing data signal SI, clock signal SCK, latch signal LAT, exchange signal CH, and switching signal SW are input to the corresponding liquid ejector head unit 51.

[0091] The branch control board 520 includes an integrated circuit including a memory and a selector. The selector is configured to correspond to each liquid ejector unit 51. For example, the print data signal SI, the memory control signal MC, the latch signal LAT, and the exchange signal CH input from the control board 580 are input to the selector. The selector selects whether to output the print data signal SI, the latch signal LAT, and the exchange signal CH to the liquid ejector unit 51 or to the memory control signal MC, the latch signal LAT, and the exchange signal CH to the memory, based on the logic level of the input latch signal LAT and the exchange signal CH. The memory stores information indicating the operating state of the print head 5 and threshold information for determining whether to update the information. The memory in this embodiment is a non-volatile memory that can be erased using ultraviolet light, specifically using a One-Time-PROM (One-Time-Programmable read-only memory), an EPROM (Electrically programmable read-only memory), etc. The memory is controlled by the memory control signal MC, clock signal SCK, latch signal LAT, and exchange signal CH, which are input via a selector.

[0092] use Figure 8 The functional structure of the liquid ejector unit 51 will be explained. Figure 8 This is a block diagram illustrating the functional structure of the liquid ejector unit 51. (See diagram below.) Figure 8 As shown, the liquid ejector unit 51 includes a wiring board 530, a liquid ejector head 510, and a relay board 120.

[0093] The wiring substrate 530 is a printed circuit board (PCB), such as a ceramic substrate or a glass epoxy substrate, and is a rigid substrate. The wiring substrate 530 is a so-called multilayer wiring substrate in which a plurality of layers are stacked. Each layer of the wiring substrate 530 that is stacked is referred to as a "wiring layer". The wiring substrate 530 is electrically connected to the plurality of liquid discharge heads 510 via the relay substrate 120. In the wiring substrate 530, the drive signal COM, the reference voltage signal VBS, the print data signal SI, the clock signal SCK, the latch signal LAT, the exchange signal CH, and the switching signal SW are respectively input from the branch wiring substrate 520 via the cable 522. The drive signal COM, the reference voltage signal VBS, the print data signal SI, the clock signal SCK, the latch signal LAT, the exchange signal CH, and the switching signal SW that are input to the wiring substrate 530 are input to the relay substrate 120 after being transmitted through the wiring substrate 530. That is, the wiring substrate 530 relays the drive signal COM, the reference voltage signal VBS, the print data signal SI, the clock signal SCK, the latch signal LAT, the exchange signal CH, and the switching signal SW that are branched between the branch wiring substrate 520 and the plurality of liquid discharge heads 510. The switching signal SW that is input to the relay substrate 120 switches whether to output the drive voltage signal VIN to the integrated circuit 121 or to input the residual vibration Vout generated by the corresponding piezoelectric element 300 to the integrated circuit 121. The wiring substrate 530 is not limited to a rigid substrate, and can be various substrates such as a flexible substrate or a rigid-flexible substrate.

[0094] The relay substrate 120 connects the liquid discharge head 510 and the wiring substrate 530. The relay substrate 120 has an integrated circuit 121. The drive signal COM, the print data signal SI, the reference voltage signal VBS, the clock signal SCK, the latch signal LAT, the exchange signal CH, and the switching signal SW input to the relay substrate 120 are input to the integrated circuit 121. However, the reference voltage signal VBS can not be input to the integrated circuit 121, but can be input to the liquid discharge head 510 via the second circuit 532 and the relay substrate 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 set the piezoelectric element 300 to be non-conductive. In addition, in the following description, the drive signal COM after the integrated circuit 121 is referred to as a drive voltage signal VIN. The integrated circuit 121 generates the drive voltage signal VIN by controlling whether to select the signal waveform included in the drive signal COM at the timing specified by the print data signal SI, the clock signal SCK, the latch signal LAT, and the exchange signal CH, and outputs the drive voltage signal VIN to the first electrode 60 of the piezoelectric element 300 included in the liquid discharge head 510. The drive voltage signal VIN is different in potential depending on the amount of ink to be discharged from the liquid discharge head 510. The integrated circuit 121 is more likely to generate heat than the wiring substrate 530.

[0095] 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 becomes a reference of displacement of the piezoelectric element 300, and is, for example, a signal of a potential of ground, DC 5.5 V, DC 6 V, or the like. The reference voltage signal VBS is a fixed potential regardless of the amount of discharge from the liquid discharge 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 being generated by the drive signal output circuit 587, but can be generated by a voltage generation circuit not shown. The piezoelectric element 300 included in the liquid discharge head 510 is driven in accordance with 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 driving of the piezoelectric element 300 is discharged from the liquid discharge head 510.

[0096] In the integrated circuit 121 included in the relay substrate 120, a residual vibration Vout generated by the liquid discharge head 510 driven on the basis of the drive voltage signal VIN is input. The integrated circuit 121 can also generate a residual vibration signal on the basis of the input residual vibration Vout.

[0097] As Figure 8As shown, in the present embodiment, the wiring substrate 530 is provided with a first circuit 531, a second circuit 532, and a temperature detection circuit 400. In the first circuit 531 and the second circuit 532, a conductor wiring formed on the wiring substrate 530 and an electronic component or an electronic circuit mounted on the wiring substrate 530, or the like are included. In the present embodiment, the first circuit 531 is a drive voltage wiring for outputting a drive signal COM for generating a drive voltage signal VIN to the relay substrate 120. In the present embodiment, the second circuit 532 is a reference voltage wiring for supplying a reference voltage signal VBS generated by the drive signal output circuit 587 and input to the wiring substrate 530 to the second electrode 80 as a common electrode.

[0098] The temperature detection circuit 400 is electrically connected to the detection resistor 401 and detects a voltage value used to calculate the resistance value of the detection resistor 401. The temperature detection circuit 400 is provided with a constant current circuit 430 and a voltage detection circuit 440. The constant current circuit 430 causes a constant current to flow to the detection resistor 401 on the basis of the control of the control section 540. The constant current circuit 430 is not limited to being provided with the wiring substrate 530, and can be provided with a branch wiring substrate 520 and a control substrate 580, or the like, in addition to the wiring substrate 530. The voltage detection circuit 440 includes a differential amplification circuit 442 and an A / D converter 444. The differential amplification circuit 442 is an amplification circuit that amplifies a voltage value generated in the detection resistor 401 by a current supplied from the constant current circuit 430, and can use an instrument amplifier. The A / D converter 444 converts an input analog voltage value into a digital signal and outputs it to the control section 540. In addition, the differential amplification circuit 442 can be omitted.

[0099] Using Figure 9 The layout of the conductor wiring and the like of the wiring substrate 530 provided in the liquid discharge head unit 51 of the present embodiment will be described. Figure 9 A diagram schematically showing the arrangement position of the temperature detection circuit 400 in the wiring substrate 530. In the present embodiment, the temperature detection circuit 400 is arranged in the wiring layer LY1 of the wiring substrate 530. Figure 9 In the example of FIG. 9, the wiring layer LY1 of the plurality of wiring layers of the wiring substrate 530 in which the first circuit 531 and the second circuit 532 are arranged is shown. On the wiring layer LY1, the temperature detection circuit 400 is arranged in addition to the first circuit 531 and the second circuit 532. Figure 9In the present embodiment, in order to facilitate understanding of the technology, the regions of the wiring layer LY1 of the wiring board 530 occupied by the first circuit 531, the second circuit 532, and the temperature detection circuit 400 are schematically shown in block form, respectively. The temperature detection circuit 400 can be formed across multiple layers of the wiring board 530, for example, and can be configured across at least the wiring layer LY1 in which the first circuit 531 and the second circuit 532 are disposed, and other wiring layers.

[0100] In Figure 9 In the present embodiment, the first distance D1, the second distance D2, and the third distance D3 are shown. The first distance D1 refers to the shortest distance between the first circuit 531 and the second circuit 532. The second distance D2 refers to the shortest distance between the first circuit 531 and the temperature detection circuit 400. The third distance D3 refers to the shortest distance between the second circuit 532 and the temperature detection circuit 400. In Figure 9 In the example described above, the first distance D1, the second distance D2, and the third distance D3 are the shortest distances in plan view of the wiring layer LY1, respectively. However, the first distance D1, the second distance D2, and the third distance D3 are not limited to the shortest distances in plan view, and can be the shortest distances in three-dimensional space including the stacking direction of the wiring layers.

[0101] Here, in the case where the temperature detection circuit 400 is disposed on the wiring board 530 inside the liquid ejecting head 510, there is a case where the measurement accuracy of the temperature achieved by the temperature detection circuit 400 decreases. The inventors have newly found that the measurement accuracy of the temperature achieved by the temperature detection circuit 400 can decrease due to the influence of heat or 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 in the case where circuits that transmit signals for driving the piezoelectric element 300 are disposed, for example.

[0102] In the liquid ejecting head 510 of the inkjet system in which the piezoelectric element 300 is used to eject liquid droplets, for example, in order to adjust the amount of introduction of the meniscus and the strength of recovery after the introduction, a drive waveform in which the potential changes greatly with respect to time, so-called pull-push-pull drive, or the like can be applied to the piezoelectric element 300. Therefore, in the liquid ejecting head unit 51, the amount of current flowing through the conductor wiring greatly changes, and thus the amount of heat generated in the electronic circuit greatly changes. As a result, it is presumed that this change in heat is transmitted to the temperature detecting circuit 400, and the measurement accuracy of the temperature achieved by the temperature detecting circuit 400 decreases. In addition, in a case where the amount of current flowing through the conductor wiring greatly changes, the induced noise from the circuits and the like around the temperature detecting circuit 400 can become large. Therefore, it is presumed that this induced noise is transmitted to the temperature detecting circuit 400, and the measurement accuracy of the temperature achieved by the temperature detecting circuit 400 decreases. In view of the above, the liquid ejecting head unit 51 of the present embodiment is configured so that, in the wiring substrate 530, in a region from the temperature detecting circuit 400 to a predetermined distance, no conductor wiring, electronic parts, and electronic circuits, and the like are disposed, from the viewpoint of reducing or preventing the influence of heat or electrical noise from the circuits around the temperature detecting circuit 400.

[0103] In Figure 9 In the example of the present embodiment, the first circuit 531 or the second circuit 532 is disposed in the region NA, and thus the measurement accuracy of the temperature achieved by the temperature detecting circuit 400 can decrease. The distance DN can be found in advance, for example, by using the relationship between the distance from the temperature detecting circuit 400 and the measurement accuracy of the temperature achieved by the temperature detecting circuit 400. Figure 9

[0104] ​In the present embodiment, the first circuit 531 and the second circuit 532 are not arranged in the region NA. In other words, the second distance D2 and the third distance D3 are set to be longer than the distance DN, and the first circuit 531 and the second circuit 532 are arranged at positions farther than the prescribed distance DN from the temperature detection circuit 400. The first distance D1 between the first circuit 531 and the second circuit 532 can be set in consideration of securing quality such as insulation between the first circuit 531 and the second circuit 532 while avoiding the increase in size of the wiring substrate 530. In the present embodiment, the second distance D2 and the third distance D3 are set to be longer than the first distance D1, respectively. By arranging the first circuit 531 and the second circuit 532 at positions farther than the first distance D1, it is possible to reduce or suppress the case where the temperature detection circuit 400 is affected by heat or electrical noise from the surrounding circuits, and it is possible to improve the detection accuracy of the temperature achieved by the temperature detection circuit 400. In the present embodiment, the distance DN is set to 0.5 mm in consideration of avoiding the influence of heat or electrical noise from the surrounding circuits while avoiding the increase in size of the wiring substrate 530. The distance DN is not limited to 0.5 mm, and it is preferable to be 0.5 mm or more, and more preferably 1 mm or more, from the viewpoint of avoiding the influence of heat or electrical noise from the surrounding circuits.

[0105] As described above, the liquid discharge head unit 51 of the present embodiment is provided with the liquid discharge head 510 and the wiring substrate 530 electrically connected to the liquid discharge head 510. The liquid discharge head 510 is provided with the detection resistor 401 for detecting the temperature of the pressure chamber 12, and the wiring substrate 530 is provided with the first circuit 531, the second circuit 532, and the temperature detection circuit 400 electrically connected to the detection resistor 401. In the first circuit 531, the second circuit 532, and the temperature detection circuit 400, the second distance D2 between the first circuit 531 and the temperature detection circuit 400 and the third distance D3 between the second circuit 532 and the temperature detection circuit 400 are set to be longer than the first distance D1 between the first circuit 531 and the second circuit 532 on the wiring substrate 530, respectively. Therefore, according to the liquid discharge head unit 51 of the present embodiment, by arranging the first circuit 531 and the second circuit 532 at positions farther than the first distance D1 from the temperature detection circuit 400, it is possible to reduce or suppress the case where the temperature detection circuit 400 is affected by heat or electrical noise from the surrounding circuits, and it is possible to improve the detection accuracy of the temperature achieved by the temperature detection circuit 400.

[0106] According to the liquid ejecting head unit 51 of this embodiment, the detection resistor 401 is arranged at the same position as the piezoelectric element 300 in the stacking direction with respect to the pressure chamber substrate 10, that is, at the same layer as the piezoelectric element 300. By arranging the detection resistor 401 near the pressure chamber 12 within the liquid ejecting 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.

[0107] According to the liquid ejecting head unit 51 of this embodiment, the temperature detection circuit 400 includes a constant current circuit 430 for causing a constant current to flow to the detection resistor 401. Thus, the measurement accuracy of the resistance value of the detection resistor 401 by the temperature detection circuit 400 is improved, and it is possible to improve the measurement accuracy of the temperature of the ink inside the pressure chamber 12.

[0108] According to the liquid ejecting head unit 51 of this 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 wiring substrate 530 with the voltage detection circuit 440, it is possible to shorten the wiring length of the voltage detection circuit 440 compared to the case where the voltage detection circuit 440 is arranged on another circuit substrate such as the control substrate 580, thereby improving the measurement accuracy of the resistance value of the detection resistor 401 by the temperature detection circuit 400, and it is possible to improve the measurement accuracy of the temperature of the ink inside the pressure chamber 12.

[0109] According to the liquid ejecting head unit 51 of this embodiment, the relay substrate 120 connects the liquid ejecting head 510 and the wiring substrate 530, and is provided with an integrated circuit 121 that generates a drive voltage signal VIN for driving the piezoelectric element 300. By providing the drive IC having a larger heat generation amount than the wiring substrate 530 on the circuit substrate located closer to the liquid ejecting head 510 than the wiring substrate 530, it is possible to reduce the heat conduction to the temperature detection circuit 400 compared to the case where the integrated circuit 121 is provided on the wiring substrate 530.

[0110] According to the liquid ejecting head unit 51 of this embodiment, the wiring substrate 530 is a rigid substrate, and the relay substrate 120 is a flexible substrate. By providing the relay substrate 120 in which the integrated circuit 121 is arranged as a flexible substrate, it is possible to suppress the increase in size of the liquid ejecting head unit 51, and by providing the wiring substrate 530 in which the temperature detection circuit 400 is arranged as a rigid substrate, it is possible to reduce the influence of heat conduction or induced noise to the temperature detection circuit 400 compared to the case where the wiring substrate 530 is a flexible substrate.

[0111] According to the liquid discharge head unit 51 of the present embodiment, the first circuit 531 and the second circuit 532 are provided at positions farther than the prescribed 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 or electrical noise from the first circuit 531 and the second circuit 532.

[0112] In the liquid discharge head unit 51 of the present embodiment, the prescribed distance DN is 0.5 mm. Therefore, it is possible to reduce or prevent the temperature detection circuit 400 from being affected by heat or electrical noise from the first circuit 531 and the second circuit 532 while avoiding the increase in size of the wiring substrate 530.

[0113] According to the liquid discharge head unit 51 of the present embodiment, the wiring substrate 530 has a plurality of wiring layers stacked, 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, and the second distance D2 and the third distance D3 are each set to be longer than the first distance D1. By arranging the first circuit 531 and the second circuit 532 at positions farther than the first distance D1, it is possible to reduce or suppress the temperature detection circuit 400 from being affected by heat or electrical noise from the surrounding circuits and the like, and to improve the detection accuracy of the temperature achieved by the temperature detection circuit 400.

[0114] According to the liquid discharge head unit 51 of the present embodiment, the piezoelectric element 300 has the first electrode 60 as a separate electrode, the second electrode 80 as a common electrode, and the 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 separate electrode. The drive signal COM has different voltage values according to the discharge amount of the liquid. The second circuit 532 is a reference voltage wiring for supplying a reference voltage signal VBS having a fixed voltage value regardless of the discharge amount to the common electrode. By arranging the circuit whose detection accuracy of the temperature detection circuit 400 is likely to significantly decrease at a position farther than the first distance D1 from the temperature detection circuit 400, it is possible to further improve the detection accuracy of the temperature achieved by the temperature detection circuit 400.

[0115] In the liquid discharge head unit 51 of this embodiment, the second distance D2 is longer than the third distance D3. Generally, the current value flowing through one of the drive voltage lines outputting the drive signal COM for generating the drive voltage signal VIN is larger than that of the reference voltage line for supplying the reference voltage signal VBS to the common electrode. Therefore, one of the heat generation amounts of the drive voltage lines can become larger than that of the reference voltage line. According to the liquid discharge head unit 51 of this embodiment, by distancing the drive voltage line, the heat generation amount of which is more likely to become larger than that of the reference voltage line, from the temperature detection circuit 400, it is possible to further reduce the heat transfer amount from the first circuit 531 and the second circuit 532 to the temperature detection circuit 400.

[0116] B. Second Embodiment:

[0117] Using Figures 10 to 12 The structure of the liquid discharge head unit 51 as a second embodiment of the present disclosure will be described. The liquid discharge head unit 51 of the second embodiment differs from the liquid discharge head unit 51 of the first embodiment in that the disposition positions of the first circuit 531 and the second circuit 532 are different from those of the wiring substrate 530b provided instead of the wiring substrate 530. Figure 10 A diagram schematically showing the disposition relationship of the temperature detection circuit 400 with the first circuit 531 and the second circuit 532 in the wiring substrate 530b as viewed in cross section. Figure 11 A diagram schematically showing the disposition relationship of the temperature detection circuit 400 with the first circuit 531 in the wiring substrate 530b as viewed in plan. Figure 12 A diagram schematically showing the disposition relationship of the temperature detection circuit 400 with the second circuit 532 in the wiring substrate 530b as viewed in plan. Figure 10 The cross-sectional view shown corresponds to Figure 11 and Figure 12 the cross-sectional view at the XII-XII position shown.

[0118] As shown in Figure 10 The wiring substrate 530b is formed in a manner in which a plurality of wiring layers are stacked. In this embodiment, three wiring layers are stacked on the wiring substrate 530b, up to the wiring layer LY3. The temperature detection circuit 400 is formed across two of the wiring layers, from the wiring layer LY1 to the wiring layer LY2.

[0119] As shown in Figure 11 The wiring layer LY1 of the wiring layers LY1 to LY3 has the first circuit 531. The second distance D2 is the shortest distance from the first circuit 531 to the temperature detection circuit 400 as viewed in plan of the wiring layer LY1. As shown in Figure 12As shown, wiring layer LY2 in wiring layers LY1 to LY3 includes a second circuit 532. The third distance D3 is the shortest distance from the first circuit 531 to the temperature detection circuit 400 when viewed from above in wiring layer LY2.

[0120] like Figure 10 As shown, region NA also includes the area from the temperature detection circuit 400 to the predetermined distance DN in the stacking direction of wiring layers LY1 to LY3. Furthermore, the first distance D1, the second distance D2, and the third distance D3 similarly refer to the shortest distances in three-dimensional space, including the stacking direction. Figure 10 In the example, the first distance D1 is the shortest distance in the stacking direction of the first circuit 531 and the second circuit 532.

[0121] like Figures 10 to 12 As shown, the first circuit 531 is positioned directly above the second circuit 532 on the wiring layer LY1. That is, the first circuit 531 and the second circuit 532 are positioned in the wiring substrate 530b that overlap when viewed from above. In contrast, in this embodiment, the first circuit 531 and the second circuit 532 are not positioned in the wiring substrate 530b that overlaps with the temperature detection circuit 400 when viewed from above. The overlapping position in the wiring substrate 530b with the temperature detection circuit 400 when viewed from above refers, for example, region NL directly below the temperature detection circuit 400 in the wiring layer LY3. In this embodiment, from the viewpoint of further reducing heat transfer to the temperature detection circuit 400 and the impact of induced noise, conductor wiring, electronic components, and electronic circuits other than the first circuit 531 and the second circuit 532 are not positioned in regions NL and NA.

[0122] According to the liquid ejector unit 51 of this embodiment, the first circuit 531 and the second circuit 532 are arranged in a position that does not overlap with the temperature detection circuit 400 when viewed from above. Therefore, the 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 decreased, and the temperature detection accuracy achieved by the temperature detection circuit 400 can be improved.

[0123] The liquid ejecting head unit 51 according to the present embodiment is provided with the wiring substrate 530b having a plurality of wiring layers LY1 to LY3 stacked. The first circuit 531 and the second circuit 532 are arranged on different wiring layers among the plurality of wiring layers LY1 to LY3, respectively. 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 detecting circuit 400 in plan view of the wiring layer LY1, and the third distance D3 is the shortest distance from the first circuit 531 to the temperature detecting circuit 400 in 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 case where the temperature detecting circuit 400 is affected by heat or electrical noise from the surrounding circuits, and it is possible to improve the detection accuracy of the temperature by the temperature detecting circuit 400.

[0124] C. Other modes:

[0125] (C1) In each of the above embodiments, the first circuit 531 is shown as an example of a driving voltage wiring for supplying a driving voltage signal VIN that differs depending on the amount of ink ejected by the liquid ejecting head 510 to the individual wiring, i.e., the first electrode 60, and the second circuit 532 is shown as an example of a reference voltage wiring for supplying a reference voltage signal VBS that is fixed regardless of the amount of ink ejected by the liquid ejecting head 510 to the common electrode, i.e., the second electrode 80. In contrast, the first circuit 531 can also be a reference voltage wiring, and the second circuit 532 can also be a driving voltage wiring. However, the first circuit 531 and the second circuit 532 are not limited to the driving voltage wiring and the reference voltage wiring, and can also be, for example, a heating voltage wiring for applying a heating voltage that causes the heating resistor 601 to generate resistance heating. The liquid ejecting head unit 51 according to this mode, in the case where the wiring substrate 530 is provided with a heating voltage wiring, can reduce or suppress the case where the temperature detecting circuit 400 is affected by heat or electrical noise from the heating voltage wiring. Furthermore, the first circuit 531 and the second circuit 532 can also be a ground wiring for grounding the temperature detecting circuit 400. The liquid ejecting head unit 51 according to this mode, in the case where the wiring substrate 530 is provided with a ground wiring, can reduce or suppress the case where the temperature detecting circuit 400 is affected by heat or electrical noise from the ground wiring. The first circuit 531 and the second circuit 532 can also be a conductor wiring for outputting a print data signal SI, a clock signal SCK, a latch signal LAT, a switching signal CH, and a switching signal SW input from the branch wiring substrate 520 to the relay substrate 120.

[0126] (C2) In each of the above-described embodiments, an example is shown in which the liquid ejecting apparatus 500 is provided with the control substrate 800 provided with the drive signal output circuit 587 that generates the drive signal COM to be input to the integrated circuit 121 that generates the drive voltage signal VIN. In contrast to this, the liquid ejecting head unit 51 can also be provided with the control substrate 580. According to the liquid ejecting head unit 51 of this mode, the liquid ejecting head unit 51 can be provided with a function of controlling the ejection of ink.

[0127] (C3) In the liquid ejecting head unit 51 of each of the above-described embodiments, the wiring substrate 530 can also be provided with a circuit breaker such as an electromagnetic removal filter that is different from the first circuit 531 and the second circuit 532. The circuit breaker cuts off 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 can also be arranged on the wiring substrate 530 in such a manner that a fourth distance from the circuit breaker to the temperature detection circuit 400 is shorter than either of the second distance D2 and the third distance D3. According to the liquid ejecting head unit 51 of this mode, the transmission of the drive signal COM and the reference voltage signal VBS to the temperature detection circuit 400 can be cut off by the circuit breaker, and the temperature detection circuit 400 can be less affected or inhibited from being affected by electrical noise from the first circuit 531 and the second circuit 532.

[0128] (C4) In each of the above-described embodiments, an example is shown in which the entire temperature detection circuit 400 is arranged at a distance farther than the first distance D1 from the first circuit 531 and the second circuit 532. However, only a specific portion of the temperature detection circuit 400 that is particularly susceptible to detection errors due to being arranged in a position close to the first circuit 531 and the second circuit 532 can be arranged at a distance farther than the first distance D1 from the first circuit 531 and the second circuit 532. In this specific portion, for example, the constant current circuit 430 and the voltage detection circuit 440 are included. At least any one of the constant current circuit 430 and the voltage detection circuit 440 can also be arranged at a distance farther than the first distance D1 from the first circuit 531 and the second circuit 532.

[0129] (C5) In each of the above-described embodiments, the temperature detection circuit 400 is configured by continuous components. However, the temperature detection circuit 400 can also be configured by being divided into a plurality of components. In this case, the plurality of components that configure the temperature detection circuit 400 can each be arranged at a distance farther than the first distance D1 from the first circuit 531 and the second circuit 532.

[0130] The present disclosure is not limited to the above-described embodiments, and can be implemented in various structures without departing from the gist thereof. For example, in order to solve part or all of the above-described problems or in order to achieve part or all of the above-described effects, the technical features in the embodiments corresponding to the technical features in each of the modes described below can be appropriately replaced or combined. Furthermore, the technical features can be appropriately deleted as long as the technical features are not described as essential technical features in the present specification.

[0131] (1) A liquid discharge head unit according to one embodiment of the present disclosure is provided. The liquid discharge head unit includes a liquid discharge head provided with a pressure chamber substrate having a plurality of pressure chambers, a piezoelectric element stacked on the pressure chamber substrate and giving pressure to each of the plurality of pressure chambers, and a drive wiring for applying a voltage for driving the piezoelectric element to the piezoelectric element, and a wiring substrate electrically connected to the liquid discharge head. A detection resistor is provided in the liquid discharge head, the detection resistor is formed of the same material as the piezoelectric element or the drive wiring, and is used to detect the temperature of the pressure chamber. A first circuit, a second circuit different from the first circuit, and a temperature detection circuit electrically connected to the detection resistor are provided on the wiring substrate. The first circuit, the second circuit, and the temperature detection circuit are provided on the wiring substrate in such a manner that 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. According to the liquid discharge head unit, by disposing the first circuit and the second circuit at a position farther than the first distance from the temperature detection circuit, it is possible to reduce or suppress the case where the temperature detection circuit is 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.

[0132] (2) In the liquid discharge head unit of the above-described mode, at least a part of the detection resistor can 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 discharge head unit of this mode, by disposing the detection resistor near the pressure chamber, it is possible to improve the measurement accuracy of the temperature of the pressure chamber by the detection resistor.

[0133] (3) In the liquid discharge head unit of the above-described aspect, the temperature detection circuit can include a constant current circuit configured to cause a constant current to flow to the detection resistor. According to the liquid discharge head unit of this aspect, it is possible to improve the measurement accuracy of the resistance value of the detection resistor implemented by the temperature detection circuit, and to improve the measurement accuracy of the temperature of the pressure chamber.

[0134] (4) In the liquid discharge head unit of the above-described aspect, the temperature detection circuit can include a voltage detection circuit configured to detect a voltage generated in the detection resistor by a current flowing from the constant current circuit. According to the liquid discharge head unit of this aspect, compared to a case where the voltage detection circuit is configured outside the liquid discharge head unit, it is possible to shorten the wiring length of the voltage detection circuit, and thus to improve the measurement accuracy of the resistance value of the detection resistor implemented by the temperature detection circuit.

[0135] (5) In the liquid discharge head unit of the above-described aspect, the liquid discharge head unit can further include a relay substrate configured to connect the liquid discharge head and the wiring substrate, and provided with an integrated circuit configured to generate a drive voltage signal for driving the piezoelectric element. According to the liquid discharge head unit of this aspect, by providing the drive IC having a larger heat generation amount than the wiring substrate on the circuit substrate located closer to the liquid discharge head than the wiring substrate, it is possible to reduce the heat conduction to the temperature detection circuit.

[0136] (6) In the liquid discharge head unit of the above-described aspect, the wiring substrate can be a rigid substrate, and the relay substrate can be a flexible substrate. According to the liquid discharge head unit of this aspect, by providing the relay substrate configured with the integrated circuit as a flexible substrate, it is possible to suppress the increase in size of the liquid discharge head unit, and by providing the wiring substrate configured with the temperature detection circuit as a rigid substrate, compared to a case where the wiring substrate is a flexible substrate, it is possible to reduce the influence of heat conduction or induced noise to the temperature detection circuit.

[0137] (7) In the liquid discharge head unit of the above-described aspect, the liquid discharge head unit can further include a control substrate different from the wiring substrate and the relay substrate, and provided with a drive signal output circuit configured to generate a drive signal to be input to the integrated circuit configured to generate the drive voltage signal. According to the liquid discharge head unit of this aspect, it is possible to provide the liquid discharge head unit with a function of controlling the discharge of liquid.

[0138] (8) In the liquid discharge head unit of the above-described aspect, the first circuit and the second circuit can be arranged at positions that do not overlap the temperature detection circuit in a plan view. With the liquid discharge head unit of this aspect, the amount of heat transfer and the induced noise from the first circuit and the second circuit to the temperature detection circuit in the stacking direction can be reduced or decreased, and the detection accuracy of the temperature by the temperature detection circuit can be improved.

[0139] (9) In the liquid discharge head unit of the above-described aspect, the first circuit and the second circuit can be arranged at positions that are farther apart from the temperature detection circuit than a predetermined distance. With the liquid discharge head unit of this aspect, the temperature detection circuit can be less affected by the heat or the electrical noise from the first circuit and the second circuit.

[0140] (10) In the liquid discharge head unit of the above-described aspect, the predetermined distance can be 0.5 mm. With the liquid discharge head unit of this aspect, the temperature detection circuit can be less affected by the heat or the electrical noise from the first circuit and the second circuit while avoiding the increase in the size of the wiring substrate.

[0141] (11) In the liquid discharge head unit of the above-described aspect, the wiring substrate can include a plurality of wiring layers stacked. The first circuit and the second circuit can be arranged on the same wiring layer of the plurality of wiring layers. The temperature detection circuit can be arranged on at least the same wiring layer. The first distance can be a distance from the first circuit to the second circuit in a plan view of the same wiring layer, the second distance can be a distance from the first circuit to the temperature detection circuit in the plan view of the same wiring layer, and the third distance can be a distance from the second circuit to the temperature detection circuit in the plan view of the same wiring layer. With the liquid discharge head unit of this aspect, the temperature detection circuit can be less affected by the heat or the electrical noise from the surrounding circuits, and the detection accuracy of the temperature by the temperature detection circuit can be improved.

[0142] (12) In the liquid discharge head unit of the above-described aspect, the wiring substrate can include a plurality of wiring layers stacked. The first circuit and the second circuit can be respectively provided on different wiring layers of the plurality of wiring layers. The first distance can be a distance from the first circuit to the second circuit in a stacking direction of the plurality of wiring layers, the second distance can be a distance from the first circuit to the temperature detection circuit in a plan view of the wiring substrate, and the third distance can be a distance from the second circuit to the temperature detection circuit in the plan view of the wiring substrate. According to the liquid discharge head unit of this aspect, the temperature detection circuit can be less affected by heat or electrical noise from surrounding circuits, and the temperature detection accuracy of the temperature detection circuit can be improved.

[0143] (13) In the liquid discharge head unit of the above-described aspect, the piezoelectric element can include individual electrodes individually provided with respect to the plurality of pressure chambers, a common electrode provided in common with respect to the plurality of pressure chambers, and a piezoelectric body provided between the individual electrodes and the common electrode. The first circuit can be a drive voltage wiring that outputs a drive signal having a voltage value that varies depending on a discharge amount of liquid, and the second circuit can be a reference voltage wiring that supplies a reference voltage signal having a fixed voltage value regardless of the discharge amount to the common electrode. According to the liquid discharge head unit of this aspect, by arranging a circuit in which the detection accuracy of the temperature detection circuit easily significantly decreases farther from the temperature detection circuit than the first distance, the temperature detection accuracy of the temperature detection circuit can be further improved.

[0144] (14) In the liquid discharge head unit of the above-described aspect, the second distance can be longer than the third distance. According to the liquid discharge head unit of this aspect, by distancing the drive voltage wiring, which is more likely to generate heat than the reference voltage wiring, farther from the temperature detection circuit, the amount of heat transferred from the first circuit and the second circuit to the temperature detection circuit can be further reduced.

[0145] (15) In the liquid discharge head unit of the above-described aspect, the wiring substrate can further include a cut-off circuit that is different from the first circuit and the second circuit and that cuts 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 cut-off circuit can be arranged on the wiring substrate in such a manner that a distance from the cut-off circuit to the temperature detection circuit is shorter than either of the second distance and the third distance. According to the liquid discharge head unit of this aspect, the cut-off circuit can cut off transmission of the drive signal and the reference voltage signal to the temperature detection circuit, and the temperature detection circuit can be less affected or less likely to be affected by electrical noise from the first circuit and the second circuit.

[0146] (16) In the liquid discharge head unit of the above-described aspect, the liquid discharge head can further include a heating resistor that heats liquid inside the pressure chamber. At least one of the first circuit and the second circuit can be a heating voltage wiring that applies a heating voltage that causes the heating resistor to generate resistance heating. According to the liquid discharge head unit of this aspect, in a case where the wiring substrate includes the heating voltage wiring, the temperature detection circuit can be less affected or less likely to be affected by heat or electrical noise from the heating voltage wiring.

[0147] (17) In the liquid discharge head unit of the above-described aspect, at least one of the first circuit and the second circuit can be a ground wiring that grounds the temperature detection circuit. According to the liquid discharge head unit of this aspect, in a case where the wiring substrate includes the ground wiring, the temperature detection circuit can be less affected or less likely to be affected by heat or electrical noise from the ground wiring.

[0148] (18) In the liquid discharge head unit of the above-described aspect, at least one of the first circuit and the second circuit can be a logic circuit.

[0149] (19) A liquid discharge apparatus is provided according to another aspect of the present disclosure. The liquid discharge apparatus includes the liquid discharge head unit of the above-described aspect, and a liquid storage portion that stores liquid discharged from the liquid discharge head unit. According to the liquid discharge apparatus, by arranging the first circuit and the second circuit at a position farther than the first distance from the temperature detection circuit, the temperature detection circuit can be less affected or less likely to be affected by heat or electrical noise from the first circuit and the second circuit, and the temperature detection circuit can improve detection accuracy of temperature.

[0150] The present disclosure can also be implemented in various ways other than the liquid ejecting head unit and the liquid ejecting apparatus. For example, it can be implemented in a method of manufacturing the liquid ejecting head unit, a method of manufacturing the liquid ejecting apparatus, and the like.

[0151] The present disclosure is not limited to the inkjet method, and can also be applied to any liquid ejecting apparatus that ejects a liquid other than ink, and a liquid ejecting head used for such liquid ejecting apparatus. For example, it can be applied to various liquid ejecting apparatuses and liquid ejecting heads thereof as follows.

[0152] (1) An image recording apparatus such as a facsimile apparatus.

[0153] (2) A color material ejecting apparatus used in the manufacture of a color filter for an image display apparatus such as a liquid crystal display.

[0154] (3) An electrode material ejecting apparatus used in the formation of an electrode for an organic EL (Electro Luminescence) display, or a Field Emission Display (FED), or the like.

[0155] (4) A liquid ejecting apparatus that ejects a liquid containing a biological organic substance used in the manufacture of a biochip.

[0156] (5) A sample ejecting apparatus as a precision pipette.

[0157] (6) A lubricating oil ejecting apparatus.

[0158] (7) A resin liquid ejecting apparatus.

[0159] (8) A liquid ejecting apparatus that ejects lubricating oil to a precision machine such as a timepiece or a camera using a needle.

[0160] (9) A liquid ejecting apparatus that ejects a transparent resin liquid such as an ultraviolet hardening resin liquid to a substrate in order to form a minute lenticular lens (optical lens) or the like used in an optical communication element or the like.

[0161] (10) A liquid ejecting apparatus that ejects an acidic or alkaline etching liquid in order to etch a substrate or the like.

[0162] (11) A liquid ejecting apparatus that has a liquid consuming head that ejects an arbitrary minute amount of liquid droplets.

[0163] The "liquid droplet" refers to a state of liquid ejected from the liquid ejection device, and is set to include a state of granular, teardrop, filament-like pulled tail. Further, the "liquid" herein is only a material such as that which can be consumed by the liquid ejection device. For example, the "liquid" is only a material in a state in which a substance is in a liquid phase, and in the "liquid", a material of a liquid body having a higher or lower viscosity, and a material of a liquid body such as sol, gel water, other inorganic solvent, organic solvent, solution, liquid resin, liquid metal (metallic melt) is also included. Further, in the "liquid", not only a liquid as a state of a substance, but also a liquid in which a functional material composed of a solid substance such as a pigment or a metal particle is dissolved, dispersed, or mixed with a particle, and the like is also included. Further, as representative examples of a combination of the first liquid and the second liquid, in addition to the combination of the ink and the reaction liquid as described in the above embodiment, the following substances can be listed.

[0164] (1) Main agent of adhesive and hardening agent

[0165] (2) Base paint and diluent of paint, transparent paint and diluent

[0166] (3) Main solvent of cell containing ink and diluent solvent of cell

[0167] (4) Metal foil pigment dispersion liquid and diluent solvent of ink for presenting metallic luster (metallic ink)

[0168] (5) Gasoline, light oil, and biofuel of fuel for vehicle

[0169] (6) Main component and protective component of medicine

[0170] (7) Phosphor and sealing material of light emitting diode (LED)

[0171] Explanation of symbols

[0172] 5…printhead; 10…pressure chamber substrate; 11…partition wall; 12…pressure chamber; 12a, 12b…end portion; 15…communication plate; 16…nozzle communication passage; 17…first manifold portion; 18…second manifold portion; 19…supply communication passage; 20…nozzle plate; 21…nozzle; 30…protective substrate; 31…holding portion; 32…through hole; 40…housing member; 41…accommodating portion; 42…third manifold portion; 43…connection port; 44…supply port; 45…plastic substrate; 46…sealing film; 47…fixed substrate; 48…opening portion; 49…plastic portion; 50…vibration plate; 51…liquid discharge head unit; 55…elastic film; 56…insulator film; 60…first electrode; 60a, 60b…end portion; 70…piezoelectric body; 70a, 70b…end portion; 71…groove portion; 80…second electrode; 80a, 80b…end portion; 85…wiring portion; 91…individual lead electrode; 92…common lead electrode; 92a, 92b…extension portion; 93, 93a, 93b…measurement lead electrode; 94, 94a, 94b…heating lead electrode; 100…manifold; 120…relay substrate; 121…integrated circuit; 300…piezoelectric element; 310…active portion; 320…inactive portion; 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 discharge apparatus; 510…liquid discharge head; 520…branch wiring substrate; 522…cable; 530, 530b…wiring substrate; 531…first circuit; 532…second circuit; 550…ink tank; 552…hose; 560…transport mechanism; 562…transport roller; 564…transport lever; 566…transport motor; 570…moving mechanism; 572…carriage; 574…transport belt; 576…moving motor; 577…pulley; 580…control substrate; 581…liquid discharge apparatus control circuit; 582…signal conversion circuit; 583…time measurement circuit; 584…power supply circuit; 585…voltage detection circuit; 586…printhead control circuit; 587…drive signal output circuit; 590…cable; 601…heating resistor; L1…first pressure chamber row; L2…second pressure chamber row; LY1 to LY3…wiring layer; NA, NL…region; P…print paper.

Claims

1. A liquid ejection head unit, comprising: a liquid ejection head provided with a pressure chamber substrate having a plurality of pressure chambers, a piezoelectric element stacked on the pressure chamber substrate and imparting pressure to each of the plurality of pressure chambers, the piezoelectric element including individual electrodes provided separately with respect to the plurality of pressure chambers, a common electrode provided in a common manner with respect to the plurality of pressure chambers, and a piezoelectric body provided between the individual electrodes and the common electrode, and a drive wiring for applying a voltage for driving the piezoelectric element to the piezoelectric element; 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 drive wiring and used for detecting a temperature of the pressure chamber is provided in the liquid ejection head, a drive voltage wiring outputting a drive signal having a different voltage value for each of an amount of ejection of liquid, a reference voltage wiring for supplying a reference voltage signal having a fixed voltage value irrespective of the amount of ejection to the common electrode, and a temperature detection circuit electrically connected to the detection resistor are provided on the wiring substrate, the temperature detection circuit includes a constant current circuit for causing a constant current to flow 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 are provided on the wiring substrate in such a manner that: a distance between the drive voltage wiring and the reference voltage wiring becomes a first distance, a distance between the drive voltage wiring and the temperature detection circuit becomes a second distance longer than the first distance, and a distance between the reference voltage wiring and the temperature detection circuit becomes a third distance longer than the first distance.

2. The liquid ejection head unit according to claim 1, wherein at least a portion of the detection resistor is disposed at the same position as the piezoelectric element in a stacking direction of the piezoelectric element with respect to the pressure chamber substrate.

3. The liquid ejection head unit according to claim 1, wherein the temperature detection circuit includes a voltage detection circuit for detecting a voltage generated in the detection resistor by the constant current.

4. The liquid ejection head unit according to claim 1, further comprising a relay substrate connecting the liquid ejection head and the wiring substrate and provided with an integrated circuit generating a drive voltage signal for driving the piezoelectric element.

5. The liquid ejection head unit according to claim 4, wherein the wiring substrate is a rigid substrate, and the relay substrate is a flexible substrate.

6. The liquid ejection head unit according to claim 4 or 5, wherein ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Further provided is a control substrate different from the wiring substrate and the relay substrate and provided with a drive signal output circuit that generates a drive signal to be input to the integrated circuit that generates the drive voltage signal.

7. The liquid ejecting head unit according to claim 1, wherein The drive voltage wiring and the reference voltage wiring are arranged at positions that do not overlap the temperature detection circuit when viewed in plan.

8. The liquid ejecting head unit according to claim 1, wherein The drive voltage wiring and the reference voltage wiring are arranged at positions that are farther apart from the temperature detection circuit than a predetermined distance.

9. The liquid ejecting head unit according to claim 8, wherein The predetermined distance is 0.5 mm.

10. The liquid ejecting head unit according to claim 1, wherein The wiring substrate has a plurality of wiring layers stacked, The drive voltage wiring and the reference voltage wiring are arranged on the same wiring layer among the plurality of wiring layers, The temperature detection circuit is arranged on at least the same wiring layer, The first distance is a distance from the drive voltage wiring to the reference voltage wiring when viewed in plan of the same wiring layer, The second distance is a distance from the drive voltage wiring to the temperature detection circuit when viewed in plan of the wiring substrate, The third distance is a distance from the reference voltage wiring to the temperature detection circuit when viewed in plan of the wiring substrate.

11. The liquid ejecting head unit according to claim 1, wherein The wiring substrate has a plurality of wiring layers stacked, The drive voltage wiring and the reference voltage wiring are arranged on different wiring layers among the plurality of wiring layers, The first distance is a distance from the drive voltage wiring to the reference voltage wiring in a stacking direction of the plurality of wiring layers, The second distance is a distance from the drive voltage wiring to the temperature detection circuit when viewed in plan of the wiring substrate, The third distance is a distance from the reference voltage wiring to the temperature detection circuit when viewed in plan of the wiring substrate.

12. The liquid ejecting head unit according to claim 1, wherein The second distance is longer than the third distance.

13. The liquid ejecting head unit according to claim 12, wherein The wiring substrate further has a cut-off circuit different from the drive voltage wiring and the reference voltage wiring and configured to cut 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 cut-off circuit are arranged on the wiring substrate in such a manner that a distance from the cut-off circuit to the temperature detection circuit becomes a fourth distance shorter than either the second distance or the third distance.

14. The liquid ejecting head unit according to claim 1, wherein At least one of the drive voltage wiring and the reference voltage wiring is a ground wiring for grounding the temperature detection circuit.

15. A liquid ejection apparatus comprising: the liquid ejection head unit according to any one of claims 1 to 14; a liquid storage portion that stores a liquid ejected from the liquid ejection head unit.

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