Liquid ejecting head and liquid ejecting apparatus

Abstract

To inhibit displacement of a piezoelectric body in conjunction with driving of a piezoelectric element.SOLUTION: A liquid ejection head includes: a pressure chamber substrate in which a plurality of pressure chambers extending in a first direction are provided; piezoelectric elements each disposed at an upper part of the pressure chamber and including a piezoelectric body, an upper electrode, and a lower electrode; and a sealing plate provided with a recessed part for housing the piezoelectric elements, the sealing plate disposed above the piezoelectric elements. When the liquid ejecting head is planarly viewed with respect to a vertical direction, the piezoelectric body has: a first area overlapping with the pressure chamber; and a second area overlapping with one of two walls included in the recessed part in the first direction. The first area and the second area are provided spaced apart from each other. A width in the first direction of a first electric potential area where electrical potential is substantially the same between an upper part and a lower part of the piezoelectric body of the second area is larger than a width in the first direction of a second electric potential area where electrical potential is not substantially the same between the upper part and the lower part of the piezoelectric body.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] Liquid ejection heads that eject liquid such as ink are widely known. For example, Patent Document 1 discloses a liquid ejection head that includes a piezoelectric element including a piezoelectric body, an upper electrode, and a lower electrode, a pressure chamber that increases or decreases the internal pressure as the piezoelectric element is driven, a sealing plate that has a recess that accommodates the piezoelectric element, and a nozzle that ejects the liquid in the pressure chamber as the pressure in the pressure chamber increases. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-020407 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional technology, when the liquid ejection head is viewed from above, the piezoelectric element is provided so as to extend widely over a range from an area overlapping with one wall of a recess provided in the sealing plate to an area overlapping with the other wall of the recess, in addition to an area overlapping with the pressure chamber. Therefore, with the conventional technology, vibrations caused by driving the piezoelectric element are transmitted to both walls of the recess via the piezoelectric element, which can change the relative positional relationship between the piezoelectric element and the sealing plate, or change the relative positional relationship between the pressure chamber substrate in which the pressure chamber is formed and the piezoelectric element. [Means for solving the problem]

[0005] In order to solve the above problems, the liquid ejection head of the present invention is a liquid ejection head comprising: a pressure chamber substrate having a pressure chamber extending in a first direction; a piezoelectric element arranged above the pressure chamber and including a piezoelectric body, an upper electrode, and a lower electrode; a sealing plate arranged above the piezoelectric element and having a recess for accommodating the piezoelectric element; wherein, when the liquid ejection head is viewed in a plane in the vertical direction, the piezoelectric body has a first region that overlaps with the pressure chamber, and a second region that overlaps with one of two walls of the recess in the first direction, the first region and the second region are arranged apart, and within the second region, the width in the first direction of a first potential region in which the potentials at the top and bottom of the piezoelectric body are approximately the same is longer than the width in the first direction of a second potential region in which the potentials at the top and bottom of the piezoelectric body are not approximately the same.

[0006] Furthermore, the liquid ejection device according to the present invention is a liquid ejection head comprising: a pressure chamber substrate having a pressure chamber extending in a first direction; a piezoelectric element arranged above the pressure chamber and including a piezoelectric body, an upper electrode, and a lower electrode; and a sealing plate arranged above the piezoelectric element and having a recess for accommodating the piezoelectric element, wherein the piezoelectric body has a first region that overlaps with the pressure chamber when the liquid ejection head is viewed in a plane in the vertical direction, and a second region that overlaps with one of two walls of the recess in the first direction, the first region and the second region being spaced apart, and the width in the first direction of a first potential region in the second region, where the potentials at the top and bottom of the piezoelectric body are approximately the same, is longer than the width in the first direction of a second potential region in which the potentials at the top and bottom of the piezoelectric body are not approximately the same. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a configuration diagram showing an example of a liquid ejection apparatus 100 according to a first embodiment of the present invention. [Figure 2] FIG. 1 is an exploded perspective view showing an example of the configuration of a liquid ejection head 1. [Figure 3] FIG. 1 is a cross-sectional view showing an example of the configuration of a liquid ejection head 1. [Figure 4] It is a cross-sectional view showing an example of the configuration of the liquid ejection head 1. [Figure 5] It is a plan view showing an example of the configuration of the actuator substrate AT. [Figure 6] It is a plan view showing an example of the configuration of the pressure chamber substrate 23. [Figure 7] It is a cross-sectional view showing an example of the configuration of the liquid ejection head 1Z according to Reference Example 1. [Figure 8] It is a plan view showing an example of the configuration of the actuator substrate AT-Z according to Reference Example 1. [Figure 9] It is a cross-sectional view showing an example of the configuration of the liquid ejection head 1W according to Reference Example 2. [Figure 10] It is a plan view showing an example of the configuration of the actuator substrate AT-W according to Reference Example 2. [Figure 11] It is a cross-sectional view showing an example of the configuration of the liquid ejection head 1B according to the second embodiment of the present invention. [Figure 12] It is a plan view showing an example of the configuration of the actuator substrate AT-B.

Mode for Carrying Out the Invention

[0008] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, in each figure, the dimensions and scales of each part are appropriately different from the actual ones. Further, the embodiments described below are preferred specific examples of the present invention, and thus various technically preferable limitations are imposed. However, the scope of the present invention is not limited to these embodiments unless there is a description specifically limiting the present invention in the following description.

[0009] <<A. First Embodiment>> Hereinafter, the liquid ejection device 100 according to the first embodiment will be described.

[0010] <<A.1. Outline of Liquid Ejection Device>> FIG. 1 is an explanatory view showing the liquid ejection device 100 according to the first embodiment.

[0011] The liquid ejection device 100 is an inkjet printing device that ejects ink onto a medium PP. The medium PP is typically printing paper, but any printing target such as a resin film or fabric can also be used as the medium PP.

[0012] As shown in FIG. 1, the liquid ejection device 100 includes a plurality of liquid ejection heads 1, a control device 8, a transport mechanism 91, a moving mechanism 92, and a liquid container 93.

[0013] The liquid container 93 stores ink and supplies the stored ink to the liquid ejection head 1. As the liquid container 93, for example, a cartridge that is detachable from the liquid ejection device 100, a bag-shaped ink pack made of flexible film, or an ink tank that can be refilled with ink can be used. The liquid container 93 stores a plurality of types of ink with different colors. Ink is an example of a "liquid."

[0014] The control device 8 includes, for example, a processing circuit such as a CPU or FPGA, and a storage circuit such as a semiconductor memory, and controls each element of the liquid ejection device 100. Here, CPU is an abbreviation for Central Processing Unit, and FPGA is an abbreviation for Field Programmable Gate Array.

[0015] The transport mechanism 91 transports the medium PP in the Y1 direction along the Y axis under the control of the control device 8. Hereinafter, the Y1 direction and the Y2 direction opposite to the Y1 direction will be collectively referred to as the Y-axis direction. Hereinafter, the X1 direction along the X axis intersecting the Y axis and the X2 direction opposite to the X1 direction will be collectively referred to as the X-axis direction. Hereinafter, the Z1 direction along the Z axis intersecting the X and Y axes and the Z2 direction opposite to the Z1 direction (an example of the "upward direction") will be collectively referred to as the Z-axis direction (an example of the "up-down direction"). In the first embodiment, as an example, a case will be described in which the X axis, Y axis, and Z axis are perpendicular to one another. However, the present invention is not limited to this example. It is sufficient that the X axis, Y axis, and Z axis intersect with one another.

[0016] Under the control of the control device 8, the moving mechanism 92 reciprocates the plurality of liquid ejection heads 1 in the X1 direction and the X2 direction. The moving mechanism 92 includes a storage case 921 that houses the plurality of liquid ejection heads 1 and an endless belt 922 to which the storage case 921 is fixed. Note that the liquid container 93 may be stored in the storage case 921 together with the liquid ejection head 1.

[0017] The control device 8 supplies a drive signal Com for driving the liquid ejection head 1 and a control signal SI for controlling the liquid ejection head 1 to the liquid ejection head 1. Then, the liquid ejection head 1 is driven by the drive signal Com under the control of the control signal SI, and ink is ejected in the Z1 direction from some or all of the plurality of nozzles N provided in the liquid ejection head 1. That is, the liquid ejection head 1 ejects ink from some or all of the plurality of nozzles N in conjunction with the conveyance of the medium PP by the conveyance mechanism 91 and the reciprocation of the liquid ejection head 1 by the moving mechanism 92, and lands the ejected ink on the surface of the medium PP, thereby forming a desired image on the surface of the medium PP. Note that the nozzles N will be described later with reference to FIGS. 2 and 3.

[0018] <<A.2. Outline of Liquid Ejection Head>> Hereinafter, the outline of the liquid ejection head 1 will be described while referring to FIGS. 2 and 3.

[0019] FIG. 2 is an exploded perspective view of the liquid ejection head 1, and FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2.

[0020] 2 and 3, the liquid ejection head 1 includes a nozzle substrate 21, compliance sheets CS1 and CS2, a communication plate 22, a pressure chamber substrate 23, a vibration plate 24, a sealing substrate 25, a flow path forming substrate 26, and a piezoelectric structure 27 including a piezoelectric element PZ. Note that, hereinafter, the configuration including the vibration plate 24 and the piezoelectric structure 27 will be referred to as an actuator substrate AT. Also, hereinafter, the configuration including the vibration plate 24, the piezoelectric structure 27, the sealing substrate 25, and the pressure chamber substrate 23 will be referred to as an actuator chip AC.

[0021] 2, the nozzle substrate 21 is a plate-like member that is long in the Y-axis direction and extends approximately parallel to the XY plane. In the first embodiment, it is assumed that the nozzle substrate 21 is manufactured by processing a silicon single crystal substrate using semiconductor manufacturing techniques such as etching, but any known material and manufacturing method may be used to manufacture the nozzle substrate 21.

[0022] In this specification, the term "substantially parallel" is a concept that includes not only cases where the two are completely parallel, but also cases where the two can be considered to be parallel when an error is taken into consideration. Specifically, the term "substantially parallel" is a concept that includes cases where the two can be considered to be parallel when an error of about 10% is taken into consideration. Furthermore, in this specification, expressions such as "substantially the same" are also terms that mean that the two can be considered to be "identical" when an error is taken into consideration, similar to "substantially parallel."

[0023] A plurality of nozzles N are formed on the nozzle substrate 21. Here, the nozzles N are through-holes provided in the nozzle substrate 21. In the first embodiment, it is assumed that the plurality of nozzles N formed on the nozzle substrate 21 include a plurality of nozzles N1 arranged to extend in the Y-axis direction and a plurality of nozzles N2 arranged to extend in the Y-axis direction at positions in the X2 direction as viewed from the plurality of nozzles N1. Hereinafter, the plurality of nozzles N1 extending in the Y-axis direction will be referred to as a nozzle row Ln1, and the plurality of nozzles N2 extending in the Y-axis direction will be referred to as a nozzle row Ln2. Furthermore, hereinafter, the nozzle row Ln1 and the nozzle row Ln2 may be collectively referred to as a nozzle row Ln.

[0024] In the first embodiment, it is assumed that the components of the liquid ejection head 1 corresponding to the nozzle row Ln1 and the components of the nozzle row Ln2 are configured to be substantially symmetrical with respect to a plane having the X-axis direction as the normal direction. Therefore, the following description will focus on the components of the liquid ejection head 1 corresponding to the nozzle row Ln1, and will omit a description of the components of the liquid ejection head 1 corresponding to the nozzle row Ln2 as appropriate.

[0025] 2 and 3, a communicating plate 22 is provided at a position in the Z2 direction (above) as viewed from the nozzle substrate 21. The communicating plate 22 is a plate-shaped member that is long in the Y-axis direction and extends approximately parallel to the XY plane. In the first embodiment, it is assumed that the communicating plate 22 is manufactured by processing a silicon single crystal substrate using semiconductor manufacturing technology, but known materials and manufacturing methods may be arbitrarily adopted to manufacture the communicating plate 22.

[0026] Ink flow paths are formed in the communication plate 22. Specifically, a single supply flow path BA1 is formed in the communication plate 22, corresponding to the nozzle row Ln1, extending in the Y-axis direction. Furthermore, a plurality of connection flow paths BK1 corresponding to the plurality of nozzles N1 and a plurality of communication flow paths BR1 corresponding to the plurality of nozzles N1 are formed in the communication plate 22, corresponding to the nozzle row Ln1. The connection flow path BK1 communicates with the supply flow path BA1 and is provided so as to extend in the Z-axis direction at a position in the X2 direction as viewed from the supply flow path BA1. The communication flow path BR1 is provided so as to extend in the Z-axis direction at a position in the X2 direction as viewed from the connection flow path BK1. The communication flow path BR1 communicates with the nozzle N1 corresponding to the communication flow path BR1.

[0027] In addition, in the communicating plate 22, one supply flow path BA2, which is an element symmetrical to one supply flow path BA1, a plurality of connection flow paths BK2, which are elements symmetrical to the plurality of connection flow paths BK1, and a plurality of communication flow paths BR2, which are elements symmetrical to the plurality of communication flow paths BR1, are formed corresponding to the nozzle row Ln2. Hereinafter, the supply flow path BA1 and the supply flow path BA2 may be collectively referred to as supply flow paths BA, the connection flow paths BK1 and the connection flow paths BK2 may be collectively referred to as connection flow paths BK, and the communication flow paths BR1 and the communication flow paths BR2 may be collectively referred to as communication flow paths BR.

[0028] 2 and 3, a pressure chamber substrate 23 is provided at a position in the Z2 direction as viewed from the communication plate 22. The pressure chamber substrate 23 is a plate-shaped member that is long in the Y-axis direction and extends approximately parallel to the XY plane. In the first embodiment, it is assumed that the pressure chamber substrate 23 is manufactured by processing a silicon single crystal substrate using semiconductor manufacturing technology, but the pressure chamber substrate 23 may be manufactured using any known material and manufacturing method.

[0029] Ink flow paths are formed in the pressure chamber substrate 23. Specifically, the pressure chamber substrate 23 is formed with a plurality of pressure chambers CV1 corresponding to the plurality of nozzles N1, a plurality of communication flow paths BC1 (not shown in FIG. 2) corresponding to the plurality of nozzles N1, and a plurality of communication flow paths BD1 (not shown in FIG. 2) corresponding to the plurality of nozzles N1, in correspondence with the nozzle row Ln1. As shown in FIG. 3, the communication flow path BC1 communicates with the connection flow path BK1 and is provided so as to extend in the X-axis direction at a position in the Z2 direction as viewed from the connection flow path BK1. The communication flow path BD1 communicates with the communication flow path BC1 and is provided so as to extend in the X-axis direction at a position in the X2 direction as viewed from the communication flow path BC1. The pressure chamber CV1 connects the X2-direction end of the communication flow path BD1 and the X1-direction end of the communication flow path BR1, and is provided so as to extend in the X-axis direction.

[0030] In addition, a plurality of pressure chambers CV2, which are elements symmetrical to the plurality of pressure chambers CV1, a plurality of communicating channels BC2, which are elements symmetrical to the plurality of communicating channels BC1, and a plurality of communicating channels BD2, which are elements symmetrical to the plurality of communicating channels BD1, are formed in the pressure chamber substrate 23, corresponding to the nozzle row Ln2. Hereinafter, the pressure chambers CV1 and CV2 may be collectively referred to as pressure chambers CV, the communicating channels BC1 and BC2 may be collectively referred to as communicating channels BC, and the communicating channels BD1 and BD2 may be collectively referred to as communicating channels BD.

[0031] 2 and 3, a diaphragm 24 is provided at a position in the Z2 direction as viewed from the pressure chamber substrate 23. The diaphragm 24 is a plate-like member that is elongated in the Y-axis direction and extends substantially parallel to the XY plane, and is a member that can vibrate elastically.

[0032] As shown in FIGS. 2 and 3, a plurality of piezoelectric elements PZ1 corresponding to the plurality of pressure chambers CV1 are provided at positions in the Z2 direction as viewed from the vibration plate 24, corresponding to the nozzle row Ln1. The piezoelectric elements PZ1 are drive elements that deform in response to changes in the potential of the drive signal Com. In other words, the piezoelectric elements PZ1 are an example of energy conversion elements that convert the electrical energy of the drive signal Com into kinetic energy. Specifically, the piezoelectric elements PZ1 are driven and deformed in response to changes in the potential of the drive signal Com. The vibration plate 24 vibrates in conjunction with the deformation of the piezoelectric elements PZ1, and this vibration fluctuates the pressure within the pressure chambers CV1. As the pressure within the pressure chambers CV1 fluctuates, ink filled inside the pressure chambers CV1 is ejected from the nozzles N1 via the communication flow path BR1.

[0033] Note that a plurality of piezoelectric elements PZ2, which are elements symmetrical to the plurality of piezoelectric elements PZ1, are provided corresponding to the nozzle row Ln2 at positions in the Z2 direction as viewed from the vibration plate 24. Hereinafter, the piezoelectric elements PZ1 and PZ2 may be collectively referred to as the piezoelectric elements PZ.

[0034] 2 and 3, a sealing substrate 25 for protecting the plurality of piezoelectric elements PZ is provided at a position in the Z2 direction as viewed from the diaphragm 24. The sealing substrate 25 is a plate-like member that is elongated in the Y-axis direction and extends substantially parallel to the XY plane. In the first embodiment, it is assumed that the sealing substrate 25 is manufactured by processing a silicon single crystal substrate using semiconductor manufacturing technology, but the sealing substrate 25 may be manufactured using any known material and manufacturing method.

[0035] 2 and 3, the sealing substrate 25 has two surfaces whose normal direction is the Z-axis direction, and the surface in the Z1 direction has a recess OB1 that defines a sealed space SP1 for accommodating a plurality of piezoelectric elements PZ1, corresponding to the nozzle row Ln1. The sealed space SP1 is a space for sealing the piezoelectric elements PZ1 and preventing the piezoelectric elements PZ1 from being deteriorated by the influence of moisture, etc. Hereinafter, when the sealing substrate 25 is viewed in a plan view in the Z1 direction, of the two walls that the recess OB1 has in the X-axis direction, the wall located in the X2 direction will be referred to as wall WA1, and the wall located in the X1 direction will be referred to as wall WB1.

[0036] In addition, the sealing substrate 25 is provided with a recess OB2 that corresponds to the nozzle row Ln2 and has a wall WA2 that is an element symmetrical to the wall WA1 and a wall WB2 that is an element symmetrical to the wall WB1, and that defines a sealed space SP2 that is an element symmetrical to the sealed space SP1. Hereinafter, the sealed spaces SP1 and SP2 may be collectively referred to as a sealed space SP, the recesses OB1 and OB2 may be collectively referred to as a recess OB, the walls WA1 and WA2 may be collectively referred to as a wall WA, and the walls WB1 and WB2 may be collectively referred to as a wall WB.

[0037] Further, the sealing substrate 25 is provided with a through hole 250. When the sealing substrate 25 is viewed in the Z1 direction, the through hole 250 is located between the sealed space SP1 and the sealed space SP2, and is a hole that penetrates from the Z1 direction surface of the sealing substrate 25 to the Z2 direction surface of the sealing substrate 25. The wiring substrate 4 is inserted into the through hole 250.

[0038] 2 and 3, a flow path forming substrate 26 is provided at a position in the Z2 direction as viewed from the communicating plate 22. The flow path forming substrate 26 is a plate-like member that is elongated in the Y-axis direction and extends substantially parallel to the XY plane. In the first embodiment, it is assumed that the flow path forming substrate 26 is formed by injection molding of a resin material, but the flow path forming substrate 26 may be manufactured using any known material and method.

[0039] An ink flow channel is formed in the flow channel forming substrate 26. Specifically, the flow channel forming substrate 26 is provided with one supply channel BB1 and one inlet HL1 corresponding to the nozzle row Ln1. The supply channel BB1 communicates with the supply channel BA1 and is provided so as to extend in the Y-axis direction at a position in the Z2 direction as viewed from the supply channel BA1. The inlet HL1 communicates with the supply channel BB1. Ink is supplied to the supply channel BB1 from the liquid container 93 via the inlet HL1. The ink supplied to the supply channel BB1 from the liquid container 93 via the inlet HL1 flows into the supply channel BA1. Some of the ink that flows into the supply channel BA1 passes through the connecting channel BK1 and fills the pressure chamber CV1. When the piezoelectric element PZ1 is driven by the drive signal Com, some of the ink filling the pressure chamber CV1 passes through the connecting channel BR1 and is ejected from the nozzle N1.

[0040] In addition, a supply flow path BB2, which is an element symmetrical to the supply flow path BB1, and an inlet HL2, which is an element symmetrical to the inlet HL1, are provided in the flow path forming substrate 26, corresponding to the nozzle row Ln2. Hereinafter, the supply flow path BB1 and the supply flow path BB2 may be collectively referred to as supply flow paths BB, and the inlet HL1 and the inlet HL2 may be collectively referred to as inlet HL.

[0041] Furthermore, a through hole 260 is provided in the flow path forming substrate 26. When the flow path forming substrate 26 is viewed in the Z1 direction, the through hole 260 is located between the supply flow path BB1 and the supply flow path BB2, and is a hole that penetrates from the Z1 direction surface of the flow path forming substrate 26 to the Z2 direction surface of the flow path forming substrate 26. The wiring substrate 4 is inserted into the through hole 260.

[0042] As shown in FIGS. 2 and 3, a wiring board 4 is mounted on the surface of the actuator substrate AT in the Z2 direction, which includes a diaphragm 24 and a piezoelectric structure 27. The wiring board 4 is a component for electrically connecting the liquid ejection head 1 to the control device 8. As the wiring board 4, for example, a flexible wiring board such as an FPC or an FFC is preferably adopted. Here, FPC is an abbreviation for Flexible Printed Circuit, and FFC is an abbreviation for Flexible Flat Cable. An integrated circuit 40 is mounted on the wiring board 4. The integrated circuit 40 is an electric circuit that switches whether to supply a drive signal Com to the piezoelectric element PZ under the control of a control signal SI.

[0043] As shown in FIGS. 2 and 3, at a position in the Z1 direction as viewed from the communication plate 22, a compliance sheet CS1 is provided so as to block the supply channel BA1 and the connection channel BK1 corresponding to the nozzle row Ln1. The compliance sheet CS1 is a plate-like member that is long in the Y-axis direction and extends substantially parallel to the XY plane. The compliance sheet CS1 is formed of an elastic material and absorbs pressure fluctuations of the ink in the supply channel BA1 and the connection channel BK1.

[0044] Note that a compliance sheet CS2, which is an element symmetric to the compliance sheet CS1, is provided on the liquid ejection head 1 corresponding to the nozzle row Ln2. Hereinafter, the compliance sheet CS1 and the compliance sheet CS2 may be collectively referred to as the compliance sheet CS.

[0045] <<A.3. Structure of Liquid Ejection Head>> Hereinafter, the structure of the liquid ejection head 1 will be described while referring to FIGS. 4 to 6.

[0046] Fig. 4 is a cross-sectional view of the liquid ejection head 1 when the vicinity of the piezoelectric element PZ1 of the liquid ejection head 1 is viewed in the Y2 direction. Note that Fig. 4 is drawn to a different scale in the X-axis direction for simplicity's sake, and the actual scale may be, for example, the scale corresponding to Fig. 3. For example, Fig. 4 illustrates the width of the pressure chamber CV1 in the X-axis direction as being approximately the same as the combined width of the communicating flow path BC1 and the communicating flow path BD1 in the X-axis direction, but in reality, as shown in Fig. 3, the pressure chamber CV1 is larger.

[0047] As shown in FIG. 4, the liquid ejection head 1 includes the communication plate 22, the pressure chamber substrate 23, the vibration plate 24, the piezoelectric structure 27, and the sealing substrate 25, as described above.

[0048] The diaphragm 24 includes an elastic film layer 241 and an insulating layer 242 laminated on the elastic film layer 241. The elastic film layer 241 is an elastic film made of, for example, silicon dioxide (SiO2) or other silicon oxide. The insulating layer 242 is an insulating layer made of, for example, zirconium oxide such as zirconium dioxide (ZrO2). The piezoelectric structure 27 is formed on the insulating layer 242.

[0049] As shown in Figure 4, the piezoelectric structure 27 corresponds to the nozzle row Ln1 and includes a plurality of piezoelectric elements PZ1 corresponding to the plurality of nozzles N1, a plurality of individual wirings LC1 corresponding to the plurality of nozzles N1, a plurality of individual electrodes QC1 corresponding to the plurality of nozzles N1, one piezoelectric body Qm common to the plurality of nozzles N1, one common electrode QB1 common to the plurality of nozzles N1, one auxiliary electrode LA1 common to the plurality of nozzles N1, one auxiliary electrode LB1 common to the plurality of nozzles N1, one auxiliary electrode Hx11 common to the plurality of nozzles N1, one auxiliary electrode Hx41 common to the plurality of nozzles N1, one auxiliary electrode HC11 common to the plurality of nozzles N1, one auxiliary layer Hy1 common to the plurality of nozzles N1, one auxiliary layer LD1 common to the plurality of nozzles N1, and one auxiliary layer HC21 common to the plurality of nozzles N1.

[0050] The piezoelectric element PZ1 is a laminated body in which a piezoelectric body Qm is interposed between an individual electrode QC1 and a common electrode QB1. Specifically, the piezoelectric element PZ1 is a portion where the individual electrode QC1, the common electrode QB1, and the piezoelectric body Qm overlap when the liquid ejection head 1 is viewed in a plan view in the Z1 direction. In the first embodiment, as an example, it is assumed that the piezoelectric body Qm is provided in the piezoelectric element PZ1 at a position in the Z2 direction as viewed from the individual electrode QC1, and the common electrode QB1 is provided at a position in the Z2 direction as viewed from the piezoelectric body Qm.

[0051] The individual electrode QC1 is formed of a conductive material such as platinum (Pt) or iridium (Ir), etc. The individual electrode QC1 is laminated on the diaphragm 24.

[0052] The piezoelectric body Qm is made of a piezoelectric material such as lead zirconate titanate (Pb(Zr,Ti)O3). Hereinafter, the portion of the piezoelectric body Qm that constitutes the multiple piezoelectric elements PZ1 will be referred to as the piezoelectric body driving region RK1, and the portion that is spaced apart from the piezoelectric body driving region RK1 in the X1 direction as viewed from the piezoelectric body driving region RK1 will be referred to as the piezoelectric body outer edge region RG1.

[0053] The piezoelectric driving region RK1 is laminated on the individual electrode QC1. When the liquid ejection head 1 is viewed in a plane in the Z1 direction, the piezoelectric driving region RK1 is provided at a position where at least a portion of the piezoelectric driving region RK1 overlaps with at least a portion of the pressure chamber CV1 and also overlaps with at least a portion of the wall WA1. The piezoelectric outer edge region RG1 is laminated on the auxiliary electrode HC11 and the auxiliary layer HC21. When the liquid ejection head 1 is viewed in a plane in the Z1 direction, the piezoelectric outer edge region RG1 is provided at a position where at least a part of the piezoelectric outer edge region RG1 overlaps with at least a part of the wall WB1.

[0054] In the first embodiment, as an example, it is assumed that the piezoelectric body Qm is provided so that the width of the piezoelectric body driving region RK1 in the X-axis direction is longer than the width of the piezoelectric body outer edge region RG1 in the X-axis direction.

[0055] The common electrode QB1 is made of a conductive material such as platinum (Pt) or iridium (Ir), etc. The common electrode QB1 is laminated on the piezoelectric body driving region RK1 of the piezoelectric body Qm. The auxiliary electrode LA1 is made of a conductive material such as gold (Au), and is stacked on the common electrode QB1. The auxiliary electrode LA1 is electrically connected to the common electrode QB1.

[0056] The individual wiring LC1 is made of a conductive material such as gold (Au). The individual wiring LC1 is laminated on the insulating layer 242, the individual electrode QC1, and the piezoelectric element driving region RK1. The individual wiring LC1 is electrically connected to the individual electrode QC1 and supplies a drive signal Com, which is supplied from the control device 8, to the individual electrode QC1. Note that in the first embodiment, it is assumed that the individual wiring LC1 is laminated directly on the individual electrode QC1, thereby electrically connecting the individual wiring LC1 and the individual electrode QC1, but the present invention is not limited to this. The individual wiring LC1 may also be electrically connected to the individual electrode QC1 via a conductor inserted into a contact hole provided in the piezoelectric element driving region RK1 of the piezoelectric element Qm.

[0057] The auxiliary electrode HC11 is made of the same conductive material as the individual electrode QC1, and is laminated on the insulating layer 242. The auxiliary electrode HC11 is arranged so as to be electrically connected to the common electrode QB1 and insulated from the individual electrode QC1. The auxiliary electrode Hx11 is made of the same conductive material as the common electrode QB1 and is stacked on the auxiliary electrode HC11. The auxiliary electrode Hx11 is arranged so as to be electrically connected to the common electrode QB1 and insulated from the individual electrode QC1. The auxiliary electrode Hx41 is made of the same conductive material as the common electrode QB1 and is laminated on the piezoelectric outer edge region RG1. The auxiliary electrode Hx41 is electrically connected to the common electrode QB1 and is insulated from the individual electrode QC1. The auxiliary electrode LB1 is made of a conductive material such as gold (Au). The auxiliary electrode LB1 is laminated on the common electrode QB1, the auxiliary electrode HC11, the auxiliary electrode Hx11, and the auxiliary electrode Hx41. The auxiliary electrode LB1 electrically connects the common electrode QB1 to the auxiliary electrode HC11, the auxiliary electrode Hx11, and the auxiliary electrode Hx41.

[0058] The auxiliary layer HC21 is formed of the same conductive material as the individual electrode QC1. However, the auxiliary layer HC21 may also be formed of a non-conductive material. The auxiliary layer HC21 is stacked on the insulating layer 242. The auxiliary layer HC21 is arranged so as to be insulated from the common electrode QB1 and the individual electrode QC1 and to be in a floating state. The auxiliary layer Hy1 is made of a conductive material such as nichrome (NiCr). However, the auxiliary layer Hy1 may also be made of a non-conductive material. The auxiliary layer Hy1 is laminated on the piezoelectric outer edge region RG1. The auxiliary layer Hy1 is arranged so as to be insulated from the common electrode QB1 and the individual electrode QC1 and to be in a floating state. The auxiliary layer LD1 is made of a conductive material such as gold (Au). However, the auxiliary layer LD1 may also be made of a non-conductive material. The auxiliary layer LD1 is laminated on the insulating layer 242, the auxiliary layer HC21, the piezoelectric outer edge region RG1, and the auxiliary layer Hy1, and is electrically connected to the auxiliary layer HC21 and the auxiliary layer Hy1. The auxiliary layer LD1 is arranged so as to be in a floating state and insulated from the common electrode QB1 and the individual electrode QC1.

[0059] In the first embodiment, as an example, a configuration is assumed in which the auxiliary layer LD1 electrically connects the auxiliary layer HC21 and the auxiliary layer Hy1, but the present invention is not limited to this configuration. The auxiliary layer HC21 may be arranged so as to be insulated from the auxiliary layer Hy1. For example, the auxiliary layer LD1 may be arranged only on the auxiliary layer Hy1 and not connected to the auxiliary layer HC21. Furthermore, for example, the liquid ejection head 1 may be configured without the auxiliary layer LD1.

[0060] 4, the piezoelectric structure 27 includes an adhesive layer 50. The adhesive layer 50 is made of an insulating adhesive. The adhesive layer 50 bonds the individual wiring LC1, the piezoelectric driving region RK1, and the auxiliary electrode LA1 to a wall WA1 of the sealing substrate 25. The adhesive layer 50 also bonds the auxiliary electrode LB1, the piezoelectric outer edge region RG1, and the auxiliary layer LD1 to a wall WB1 of the sealing substrate 25.

[0061] Although not shown in the drawings, the piezoelectric structure 27 corresponds to the nozzle row Ln2 and includes a plurality of piezoelectric elements PZ2 which are elements symmetrical to the plurality of piezoelectric elements PZ1, a plurality of individual wirings LC2 which are elements symmetrical to the plurality of individual wirings LC1, a plurality of individual electrodes QC2 which are elements symmetrical to the plurality of individual electrodes QC1, one piezoelectric body Qm, one common electrode QB2 which is an element symmetrical to the common electrode QB1, one auxiliary electrode LA2 which is an element symmetrical to the auxiliary electrode LA1, and one auxiliary electrode LB1 which is an element symmetrical to the auxiliary electrode LB1. The nozzle array Ln2 includes one auxiliary electrode LB2 which is a symmetrical element with the auxiliary electrode Hx11, one auxiliary electrode Hx12 which is a symmetrical element with the auxiliary electrode Hx41, one auxiliary layer Hy2 which is a symmetrical element with the auxiliary layer Hy1, one auxiliary layer LD2 which is a symmetrical element with the auxiliary layer LD1, one auxiliary electrode HC12 which is a symmetrical element with the auxiliary electrode HC11, and one auxiliary layer HC22 which is a symmetrical element with the auxiliary layer HC21. Furthermore, the piezoelectric element Qm corresponds to the nozzle array Ln2 and includes a piezoelectric element driving region RK2 which is a symmetrical element with the piezoelectric element driving region RK1, and a piezoelectric element outer edge region RG2 which is a symmetrical element with the piezoelectric element outer edge region RG1. Hereinafter, the individual wirings LC1 and LC2 will be collectively referred to as individual wirings LC, the individual electrodes QC1 and QC2 will be collectively referred to as individual electrodes QC, the common electrodes QB1 and QB2 will be collectively referred to as common electrodes QB, the auxiliary electrodes LA1 and LA2 will be collectively referred to as auxiliary electrodes LA, the auxiliary electrodes LB1 and LB2 will be collectively referred to as auxiliary electrodes LB, the auxiliary electrodes Hx11 and Hx12 will be collectively referred to as auxiliary electrodes Hx1, and the auxiliary electrodes Hx41 and Hx42 will be collectively referred to as auxiliary electrodes Hx4. The electrodes Hx1 and Hx2 may be collectively referred to as the auxiliary layer Hy, the auxiliary layers Hy1 and Hy2 may be collectively referred to as the auxiliary layer Hy, the auxiliary layers LD1 and LD2 may be collectively referred to as the auxiliary layer LD, the auxiliary electrodes HC11 and HC12 may be collectively referred to as the auxiliary electrode HC1, the auxiliary layers HC21 and HC22 may be collectively referred to as the auxiliary layer HC2, the piezoelectric driving regions RK1 and RK2 may be collectively referred to as the piezoelectric driving regions RK, and the piezoelectric outer edge regions RG1 and RG2 may be collectively referred to as the piezoelectric outer edge regions RG.

[0062] 4, as described above, the sealing substrate 25 is provided with a recess OB1 that defines a sealing space SP1 for accommodating a plurality of piezoelectric elements PZ1, corresponding to the nozzle row Ln1. Furthermore, the sealing substrate 25 is provided with a groove ON1 in the wall WB1, corresponding to the nozzle row Ln1, for accommodating excess adhesive of the adhesive contained in the adhesive layer 50.

[0063] 4, as described above, the sealing substrate 25 is provided with a recess OB2, which is an element symmetrical to the recess OB1, and a groove portion ON2, which is an element symmetrical to the groove portion ON1, corresponding to the nozzle row Ln2. Hereinafter, the groove portion ON1 and the groove portion ON2 may be collectively referred to as the groove portion ON.

[0064] Below, we will consider the voltage applied to the piezoelectric body Qm. Specifically, we will consider the potential difference between the potential on the lower surface (surface in the Z1 direction) of the piezoelectric body Qm and the potential on the upper surface (surface in the Z2 direction) of the piezoelectric body Qm at each part of the piezoelectric body Qm. Note that when "potential difference" is mentioned in the following explanation, this potential difference refers to the "potential difference" at each part of the piezoelectric body Qm when the drive signal Com is applied to the individual electrode QC1 and the reference potential VBS is applied to the common electrode QB1.

[0065] 4, the voltage applied to the piezoelectric body Qm in the piezoelectric body driving region RK1 is referred to as voltage VK. Specifically, voltage VK is the potential difference between the potential of the lower surface of the piezoelectric body Qm and the potential of the upper surface of the piezoelectric body Qm in the piezoelectric body driving region RK1. As described above, in the piezoelectric body driving region RK1, the individual electrode QC1 connected to the lower surface of the piezoelectric body Qm is supplied with a driving signal Com. When the driving signal Com drives the piezoelectric element PZ, the potential of the driving signal Com fluctuates. However, in the first embodiment, for the sake of convenience, the potential of the driving signal Com is referred to as a driving potential VC. In addition, in the piezoelectric body driving region RK1, the common electrode QB1 connected to the upper surface of the piezoelectric body Qm is electrically connected to a power supply wiring set to a reference potential VBS. Note that the first embodiment assumes the case where "VC>VBS." Therefore, in the first embodiment, the voltage VK is "VK=VC-VBS>0," which is greater than "0V."

[0066] As shown in FIG. 4, the piezoelectric outer edge region RG1 includes a partial region RG11, a partial region RG12, a partial region RG13, and a partial region RG14. The partial region RG11 is a region including the end portion in the X2 direction of the piezoelectric body outer edge region RG1, and is a region connected to the auxiliary electrode HC11 on the lower surface of the piezoelectric body Qm and connected to the auxiliary electrode Hx41 on the upper surface of the piezoelectric body Qm. The partial region RG12 is a region adjacent to the partial region RG11 in the X1 direction when viewed from the partial region RG11, and is a region connected to the auxiliary electrode HC11 on the lower surface of the piezoelectric body Qm and connected to the adhesive layer 50 on the upper surface of the piezoelectric body Qm. The partial region RG13 is a region adjacent to the partial region RG12 in the X1 direction when viewed from the partial region RG12, and is a region that connects to the insulating layer 242 on the lower surface of the piezoelectric body Qm and connects to the adhesive layer 50 on the upper surface of the piezoelectric body Qm. The partial region RG14 is adjacent to the partial region RG13 in the X1 direction when viewed from the partial region RG13, and is a region that includes the end portion of the piezoelectric outer edge region RG1 in the X1 direction, and is a region that connects to the auxiliary layer HC21 on the lower surface of the piezoelectric body Qm and connects to the auxiliary layer Hy1 on the upper surface of the piezoelectric body Qm.

[0067] 4, the voltage applied to the piezoelectric body Qm in the partial region RG11 is referred to as a voltage VG1. Specifically, the voltage VG1 is the potential difference between the potential of the lower surface of the piezoelectric body Qm and the potential of the upper surface of the piezoelectric body Qm in the partial region RG11. As described above, in the partial region RG11, the auxiliary electrode HC11 connected to the lower surface of the piezoelectric body Qm is set to the reference potential VBS. In the partial region RG11, the auxiliary electrode Hx41 connected to the upper surface of the piezoelectric body Qm is electrically connected to the auxiliary electrode HC11 and is set to the reference potential VBS. Therefore, in the first embodiment, the voltage VG1 is "VG1 = VBS - VBS = 0", and even when errors such as noise are taken into consideration, the voltage VG1 is approximately the same as "0 V". In other words, in the partial region RG11, the potentials at the top and bottom of the piezoelectric body Qm are approximately the same.

[0068] 4, the voltage applied to the piezoelectric body Qm in the partial region RG12 is referred to as a voltage VG2. Specifically, the voltage VG2 is the potential difference between the potential of the lower surface of the piezoelectric body Qm and the potential of the upper surface of the piezoelectric body Qm in the partial region RG12. As described above, in the partial region RG12, the auxiliary electrode HC11 connected to the lower surface of the piezoelectric body Qm is set to the reference potential VBS. In the partial region RG12, the adhesive layer 50 connected to the upper surface of the piezoelectric body Qm is an insulator. In the first embodiment, for convenience of explanation, the potential of the insulator is assumed to be a potential V0, which is lower than the reference potential VBS. Therefore, in the first embodiment, the voltage VG2 is "VG2=VBS-V0>0", which is greater than "0V". In other words, in the partial region RG12, the potentials of the upper and lower parts of the piezoelectric body Qm are different.

[0069] 4, the voltage applied to the piezoelectric body Qm in the partial region RG13 is referred to as a voltage VG3. Specifically, the voltage VG3 is the potential difference between the potential of the lower surface of the piezoelectric body Qm and the potential of the upper surface of the piezoelectric body Qm in the partial region RG13. As described above, in the partial region RG13, the insulating layer 242 connected to the lower surface of the piezoelectric body Qm is an insulator. In the partial region RG13, the adhesive layer 50 connected to the upper surface of the piezoelectric body Qm is also an insulator. Therefore, in the first embodiment, the voltage VG3 is "VG3 = V0 - V0 = 0", and even when errors such as noise are taken into consideration, the voltage VG3 is approximately the same as "0 V". In other words, in the partial region RG13, the potentials at the top and bottom of the piezoelectric body Qm are approximately the same.

[0070] 4, the voltage applied to the piezoelectric body Qm in the partial region RG14 is referred to as a voltage VG4. Specifically, the voltage VG4 is the potential difference between the potential of the lower surface of the piezoelectric body Qm and the potential of the upper surface of the piezoelectric body Qm in the partial region RG14. As described above, in the partial region RG14, the auxiliary layer HC21 connected to the lower surface of the piezoelectric body Qm is in a floating state. In the partial region RG14, the auxiliary layer Hy1 connected to the upper surface of the piezoelectric body Qm is also in a floating state and is electrically connected to the auxiliary layer HC21. In the first embodiment, for convenience of explanation, the potential of a conductor in a floating state is assumed to be potential V0. Therefore, in the first embodiment, the voltage VG4 is "VG4 = V0 - V0 = 0", and even when errors such as noise are taken into consideration, the voltage VG4 is approximately the same as "0 V". In other words, in the partial region RG14, the potentials at the top and bottom of the piezoelectric body Qm are approximately the same.

[0071] In the first embodiment, the region of the piezoelectric body outer edge region RG1 where the potential of the lower surface of the piezoelectric body Qm and the potential of the upper surface of the piezoelectric body Qm are substantially the same is referred to as the "same potential region." Also, in the first embodiment, the region of the piezoelectric body outer edge region RG1 where the potential of the lower surface of the piezoelectric body Qm and the potential of the upper surface of the piezoelectric body Qm are different is referred to as the "different potential region." In the first embodiment, partial regions RG11, RG13, and RG14 correspond to the "same potential region," and partial region RG12 corresponds to the "different potential region."

[0072] In the first embodiment, the piezoelectric structure 27 is provided so that the sum of the width of the partial region RG11 in the X-axis direction, the width of the partial region RG13 in the X-axis direction, and the width of the partial region RG14 in the X-axis direction is longer than the width of the partial region RG12 in the X-axis direction. That is, in the first embodiment, the piezoelectric structure 27 is provided so that the width of the same potential region in the X-axis direction is longer than the width of the different potential region in the X-axis direction. Furthermore, in the first embodiment, the piezoelectric structure 27 may be provided so that the sum of the width of the partial region RG11 in the X-axis direction and the width of the partial region RG14 in the X-axis direction is longer than the sum of the width of the partial region RG12 in the X-axis direction and the width of the partial region RG13 in the X-axis direction.

[0073] Fig. 5 is a plan view of the actuator substrate AT provided in the liquid ejection head 1 when viewed in plan in the Z1 direction. In Fig. 5, in addition to the actuator substrate AT including the vibration plate 24 and the piezoelectric element Qm, the sealing substrate 25 provided at a position (above) in the Z2 direction as viewed from the actuator substrate AT, and a plurality of pressure chambers CV provided at a position (below) in the Z1 direction as viewed from the actuator substrate AT are indicated by dashed lines.

[0074] As described above, the actuator substrate AT has the diaphragm 24 and the piezoelectric body Qm laminated on the diaphragm 24.

[0075] 5, as described above, the piezoelectric body Qm has a piezoelectric body driving region RK1 that extends in the Y-axis direction in correspondence with the nozzle row Ln1. When the liquid ejection head 1 is viewed from above, the piezoelectric body driving region RK1 is provided so as to overlap with the multiple pressure chambers CV1 and at least a portion of the wall WA1. It should be noted that the piezoelectric body driving region RK1 is provided with a plurality of openings KK1. The openings KK1 are through-holes that penetrate the piezoelectric body driving region RK1 in the Z-axis direction. When the liquid ejection head 1 is viewed in a plan view, each opening KK1 is provided in the piezoelectric body driving region RK1 between two adjacent pressure chambers CV1 among the plurality of pressure chambers CV1. Because the piezoelectric body driving region RK1 is provided with the openings KK1, when the piezoelectric element PZ1 corresponding to one of the two adjacent pressure chambers CV1 is driven by the drive signal Com, it is possible to prevent vibrations caused by the drive from propagating to the piezoelectric element PZ1 corresponding to the other of the two adjacent pressure chambers CV1. Furthermore, it has been found that the boundary between the piezoelectric body Qm's active portion (piezoelectric body driving region RK1) and its adjacent inactive portion in the X2 direction is prone to damage to the piezoelectric body with use. Because the moving and non-moving portions of the piezoelectric body Qm are adjacent to each other when driven, the difference in strain of the piezoelectric body Qm increases, leading to damage. To mitigate this, in this embodiment, the boundary is positioned so that it overlaps with the wall WA1 when the liquid ejection head 1 is viewed from above, and the wall WA1 presses against the boundary. This reduces the movement of the portion of the piezoelectric body driving region RK1 that overlaps with the wall WA1, thereby reducing the damage. To achieve this configuration, as described above, a portion of the piezoelectric body driving region RK1 is positioned so that it overlaps with the wall WA when viewed from above. Even in a position overlapping with wall WA1 in plan view, if the piezoelectric element Qm is provided at a distance from the piezoelectric element drive region RK1, as in the position overlapping with wall WB1 in plan view described below, it is possible to achieve the effects of reducing foreign matter contamination, sealing performance due to vibration transmission, and suppressing degradation of ejection characteristics. However, the wall WA1 side is more susceptible to damage at the boundary between the active and inactive parts during use than the wall WB1 side. This is thought to be due to the fact that the wall WA1 side is closer to the nozzle N1, which could prevent ejection itself if damage occurs, and because the drive signal Com is applied to the individual electrode QC1 from the wall WA1 side, the voltage drop is smaller on the wall WA1 side than on the wall WB1, making it more likely to receive a large voltage. Therefore, in this embodiment, we prioritized reducing damage during use on the wall WA1 side, so a portion of the piezoelectric element drive region RK1 overlaps with wall WA in plan view.

[0076] As described above, the piezoelectric element Qm has a piezoelectric element driving region RK2 that corresponds to the nozzle row Ln2 and is an element symmetrical to the piezoelectric element driving region RK1. The piezoelectric element driving region RK2 has a plurality of openings KK2 that are elements symmetrical to the plurality of openings KK1.

[0077] 5, the piezoelectric element Qm has a piezoelectric element outer edge region RG1 corresponding to the nozzle row Ln1, as described above. When the liquid ejection head 1 is viewed from above, the piezoelectric element outer edge region RG1 overlaps with at least a portion of the wall WB1 and is spaced apart from the piezoelectric element driving region RK1.

[0078] The piezoelectric outer edge region RG1 has an extending portion RGy extending in the Y-axis direction at a position in the X1 direction as viewed from the piezoelectric drive region RK1, and two extending portions RGx extending in the X-axis direction at positions in the Y1 direction and the Y2 direction as viewed from the piezoelectric drive region RK1. The extending portion RGy has a central portion RGm that overlaps with the pressure chambers CV1 when viewed from the liquid ejection head 1 in the X-axis direction, and end portions RGs that do not overlap with the pressure chambers CV1 when viewed from the liquid ejection head 1 in the X-axis direction. In the first embodiment, as an example, it is assumed that the piezoelectric outer edge region RG1 is provided so that the width of the central portion RGm in the X-axis direction is longer than the width of the end portions RGs in the X-axis direction. In the first embodiment, as an example, it is assumed that the piezoelectric outer edge region RG1 is provided so that the width of the central portion RGm in the X-axis direction is longer than the width of the extending portion RGx in the Y-axis direction.

[0079] As described above, the piezoelectric element Qm has a piezoelectric element outer edge region RG2 that corresponds to the nozzle row Ln2 and is an element symmetrical to the piezoelectric element outer edge region RG1. The piezoelectric element outer edge region RG2 has an extension portion RGy and an extension portion RGx.

[0080] 5, the piezoelectric body Qm has a piezoelectric body central region RP1 that extends in the Y-axis direction in correspondence with the nozzle row Ln1. The piezoelectric body central region RP1 is provided so as to overlap with the wiring substrate 4 when the liquid ejection head 1 is viewed in plan. A conductive wiring (not shown) is provided above the piezoelectric body central region RP1 to electrically connect the wiring provided on the wiring substrate 4 and the individual wiring LC.

[0081] As described above, the piezoelectric body Qm has a piezoelectric body central region RP2 that is an element symmetrical to the piezoelectric body central region RP1, corresponding to the nozzle row Ln2. Hereinafter, the piezoelectric body central region RP1 and the piezoelectric body central region RP2 may be collectively referred to as the piezoelectric body central region RP.

[0082] FIG. 6 is a plan view of the pressure chamber substrate 23 provided in the liquid ejection head 1, in the vicinity of the pressure chamber CV1, when viewed in plan in the Z1 direction.

[0083] As shown in FIG. 6, in the pressure chamber substrate 23, a pressure chamber CV1, a communication flow path BC1, and a communication flow path BD1 are formed corresponding to the nozzle row Ln1. The pressure chamber CV1 extends in the X-axis direction and communicates with the communication flow path BR1. The communication flow path BC1 extends in the X-axis direction and communicates with the connection flow path BK1. The communication flow path BD1 extends in the X-axis direction and communicates the pressure chamber CV1 and the communication flow path BC1. In the first embodiment, the cross-sectional area of the communication flow path BD1 is smaller than the cross-sectional area of the pressure chamber CV1 and smaller than the cross-sectional area of the communication flow path BC1. For example, when the pressure chamber substrate 23 is viewed in plan in the Z-axis direction, the width dBD in the Y-axis direction of the communication flow path BD1 is shorter than the width dBC in the Y-axis direction of the communication flow path BC1 and shorter than the width dCV in the Y-axis direction of the pressure chamber CV1. Note that a portion of the pressure chamber substrate 23 that defines the wall surface of the communication flow path BD1 is referred to as a throttle portion SB1.

[0084] Further, in the pressure chamber substrate 23, as described above, corresponding to the nozzle row Ln2, a pressure chamber CV2 which is an element symmetric to the pressure chamber CV1, a communication flow path BC2 which is an element symmetric to the communication flow path BC1, and a communication flow path BD2 which is an element symmetric to the communication flow path BD1 are formed.

[0085] <<A.4. Reference Example>> Hereinafter, in order to clarify the advantages of the liquid ejection head 1 according to the first embodiment, a liquid ejection head 1Z according to Reference Example 1 and a liquid ejection head 1W according to Reference Example 2 will be described.

[0086] FIG. 7 is a cross-sectional view of the liquid ejection head 1Z when viewed in cross-section in the Y2 direction for the liquid ejection head 1Z according to Reference Example 1. FIG. 8 is a plan view of the actuator substrate AT-Z provided on the liquid ejection head 1Z when viewed in plan in the Z1 direction.

[0087] 7 and 8, the liquid ejection head 1Z differs from the liquid ejection head 1 according to the first embodiment in that it includes a piezoelectric structure 27Z including a piezoelectric element QmZ instead of the piezoelectric structure 27 including the piezoelectric element Qm. The piezoelectric element QmZ differs from the piezoelectric element Qm according to the first embodiment in that it includes a piezoelectric element extending region RZ1 instead of a piezoelectric element driving region RK1 and a piezoelectric element outer edge region RG1 corresponding to the nozzle row Ln1.

[0088] 7 and 8, when the liquid ejection head 1Z is viewed in a plane in the Z1 direction, the piezoelectric element extending region RZ1 is provided in a range where at least a portion of the piezoelectric element extending region RZ1 overlaps with the pressure chamber CV1, where at least a portion of the piezoelectric element extending region RZ1 overlaps with at least a portion of the wall WA1, and where at least a portion of the piezoelectric element extending region RZ1 overlaps with at least a portion of the wall WB1. In other words, the piezoelectric element extending region RZ1 of the piezoelectric element QmZ is a region obtained by expanding the extension ranges of the piezoelectric element driving region RK1 and the piezoelectric element outer edge region RG1 of the piezoelectric element Qm, as in the conventional technology, so that the piezoelectric element driving region RK1 and the piezoelectric element outer edge region RG1 are connected together.

[0089] Piezoelectric structure 27Z also differs from piezoelectric structure 27 according to the first embodiment in that it includes a piezoelectric element PZ-Z1 instead of piezoelectric element PZ1. Piezoelectric element PZ-Z1 differs from piezoelectric element PZ1 according to the first embodiment in that it includes a piezoelectric element QmZ instead of piezoelectric element Qm and a common electrode QB-Z1 instead of common electrode QB1. Piezoelectric structure 27Z also differs from piezoelectric structure 27 according to the first embodiment in that it includes an auxiliary electrode LB-Z1 instead of auxiliary electrode LB1. Piezoelectric structure 27Z also differs from piezoelectric structure 27 according to the first embodiment in that it does not include auxiliary electrodes Hx11 and Hx41. Piezoelectric structure 27Z also differs from piezoelectric structure 27 according to the first embodiment in that it includes an auxiliary layer HC-Z instead of auxiliary electrode HC11 and auxiliary layer HC21.

[0090] The common electrode QB-Z1 is made of the same conductive material as the common electrode QB1 according to embodiment 1. The common electrode QB-Z1 is laminated on the piezoelectric body QmZ. The auxiliary electrode LB-Z1 is made of the same conductive material as the auxiliary electrode LB1 according to the first embodiment. The auxiliary electrode LB-Z1 is stacked on the common electrode QB-Z1. The auxiliary layer HC-Z is formed of the same conductive material as the individual electrode QC1. The auxiliary layer HC-Z is laminated on the insulating layer 242. The auxiliary layer HC-Z is electrically connected to the auxiliary layer Hy1 via the auxiliary layer LD1. The auxiliary layer HC-Z is arranged so as to be in a floating state, insulated from the common electrode QB-Z1 and the individual electrode QC1.

[0091] 7, the region of the piezoelectric body extending region RZ1 that constitutes the piezoelectric element PZ-Z1 is referred to as the piezoelectric body driving region RZK1. In the piezoelectric body driving region RZK1, the lower surface of the piezoelectric body QmZ is connected to the individual electrode QC1, and the upper surface of the piezoelectric body QmZ is connected to the common electrode QB-Z1. In the following description, the portion of the piezoelectric body extending region RZ1 that is located below the wall WB1 and supports the wall WB1 will be referred to as a piezoelectric body outer edge region RZG1. In the following description, the portion of the piezoelectric extension region RZ1 between the piezoelectric driving region RZK1 and the piezoelectric outer edge region RZG1 is referred to as the piezoelectric connection region RZM1. In the piezoelectric connection region RZM1, the lower surface of the piezoelectric body QmZ is connected to the insulating layer 242, and the upper surface of the piezoelectric body QmZ is connected to the common electrode QB-Z1.

[0092] In the following description, a region of the piezoelectric body outer edge region RZG1 that includes the end portion of the piezoelectric body outer edge region RZG1 in the X2 direction is referred to as a partial region RZ11. In the partial region RZ11, the lower surface of the piezoelectric body QmZ is connected to the auxiliary layer HC-Z, and the upper surface of the piezoelectric body QmZ is connected to the common electrode QB-Z1. In the following description, the region of the piezoelectric body outer edge region RZG1 adjacent to the partial region RZ11 in the X1 direction as viewed from the partial region RZ11 is referred to as the partial region RZ12. In the partial region RZ12, the lower surface of the piezoelectric body QmZ is connected to the auxiliary layer HC-Z, and the upper surface of the piezoelectric body QmZ is connected to the adhesive layer 50. In the following description, the region of the piezoelectric body outer edge region RZG1 that is adjacent to the partial region RZ12 in the X1 direction as viewed from the partial region RZ12 and that includes the end of the piezoelectric body outer edge region RZG1 in the X1 direction is referred to as the partial region RZ13. In the partial region RZ13, the lower surface of the piezoelectric body QmZ is connected to the auxiliary layer HC-Z, and the upper surface of the piezoelectric body QmZ is connected to the auxiliary layer Hy1.

[0093] It is assumed that the liquid ejection head 1Z has a configuration that is substantially plane-symmetrical with respect to a plane having the X-axis direction as the normal direction.

[0094] The voltage applied to the piezoelectric body QmZ will be considered below.

[0095] As shown in FIG. 7, in the piezoelectric body driving region RZK1, a voltage VK (=VC-VBS>0) is applied to the piezoelectric body QmZ.

[0096] As shown in FIG. 7, the voltage applied to the piezoelectric body QmZ in the piezoelectric body connection region RZM1 is referred to as a voltage VM. As described above, in the piezoelectric body connection region RZM1, the insulating layer 242 connected to the lower surface of the piezoelectric body QmZ is an insulator. In the piezoelectric body connection region RZM1, the common electrode QB-Z1 connected to the upper surface of the piezoelectric body QmZ is set to the reference potential VBS. Therefore, in Reference Example 1, the voltage VM is "VM=VBS-V0>0", which is greater than "0V". In other words, in the piezoelectric body connection region RZM1, the potentials at the top and bottom of the piezoelectric body QmZ are different.

[0097] As shown in FIG. 7, in the partial region RZ11, the voltage applied to the piezoelectric body QmZ is referred to as a voltage VZ1. As described above, in the partial region RZ11, the auxiliary layer HC-Z connected to the lower surface of the piezoelectric body QmZ is in a floating state. In the partial region RZ11, the common electrode QB-Z1 connected to the upper surface of the piezoelectric body QmZ is set to the reference potential VBS. Therefore, in Reference Example 1, the voltage VZ1 is "VZ1=VBS-V0>0", which is greater than "0V". In other words, in the partial region RZ11, the potentials at the top and bottom of the piezoelectric body QmZ are different.

[0098] Furthermore, in the partial region RZ11, the auxiliary layer HC-Z connected to the lower surface of the piezoelectric body QmZ is a conductor, and in the partial region RZ11, the common electrode QB-Z1 connected to the upper surface of the piezoelectric body QmZ is a conductor, so that a parasitic capacitance occurs between the auxiliary layer HC-Z and the common electrode QB-Z1.

[0099] As shown in FIG. 7, the voltage applied to the piezoelectric body QmZ in the partial region RZ12 is referred to as a voltage VZ2. As described above, in the partial region RZ12, the auxiliary layer HC-Z connected to the lower surface of the piezoelectric body QmZ is in a floating state. In the partial region RZ12, the adhesive layer 50 connected to the upper surface of the piezoelectric body QmZ is an insulator. Therefore, in Reference Example 1, the voltage VZ2 is "VZ2 = V0 - V0 = 0", and even when errors such as noise are taken into consideration, the voltage VZ2 is approximately the same as "0 V". In other words, in the partial region RZ12, the potentials at the top and bottom of the piezoelectric body QmZ are approximately the same.

[0100] As shown in FIG. 7, the voltage applied to the piezoelectric body QmZ in the partial region RZ13 is referred to as a voltage VZ3. As described above, in the partial region RZ13, the auxiliary layer HC-Z connected to the lower surface of the piezoelectric body QmZ is in a floating state. In the partial region RZ13, the auxiliary layer Hy1 connected to the upper surface of the piezoelectric body QmZ is in a floating state and is electrically connected to the auxiliary layer HC-Z. Therefore, in Reference Example 1, the voltage VZ3 is "VZ3 = V0 - V0 = 0", and even when errors such as noise are taken into consideration, the voltage VZ3 is approximately the same as "0 V". In other words, in the partial region RZ13, the potentials at the top and bottom of the piezoelectric body QmZ are approximately the same.

[0101] In Reference Example 1, the regions of the piezoelectric body connection region RZM1 and the piezoelectric body outer edge region RZG1 where the potential of the lower surface of the piezoelectric body QmZ and the potential of the upper surface of the piezoelectric body QmZ are approximately the same are referred to as "same potential regions." Also, in Reference Example 1, the regions of the piezoelectric body connection region RZM1 and the piezoelectric body outer edge region RZG1 where the potential of the lower surface of the piezoelectric body QmZ and the potential of the upper surface of the piezoelectric body QmZ are different are referred to as "different potential regions." In Reference Example 1, partial regions RZ12 and RZ13 correspond to the "same potential regions," and partial regions RZ11 correspond to the "different potential regions."

[0102] In Reference Example 1, the piezoelectric structure 27Z is provided so that the sum of the width of the piezoelectric body connection region RZM1 in the X-axis direction and the width of the partial region RZ11 in the X-axis direction is greater than the sum of the width of the partial region RZ12 in the X-axis direction and the width of the partial region RZ13 in the X-axis direction. In other words, in Reference Example 1, the piezoelectric structure 27Z is provided so that the width of the same potential region in the X-axis direction is shorter than the width of the different potential region in the X-axis direction.

[0103] Thus, in the piezoelectric body QmZ according to Reference Example 1, in the regions other than the piezoelectric body driving region RZK1 constituting the piezoelectric element PZ-Z1, i.e., the piezoelectric body connection region RZM1 and the piezoelectric body outer edge region RZG1, the width in the X-axis direction of the different potential region is longer than the width in the X-axis direction of the same potential region. Therefore, according to Reference Example 1, the voltage applied to the piezoelectric body QmZ displaces the piezoelectric body QmZ in the Z-axis direction, which may change the relative positional relationship between the piezoelectric body QmZ and the sealing substrate 25. If the relative positional relationship between the piezoelectric body QmZ and the sealing substrate 25 changes, the sealing ability of the sealing substrate 25 to seal the piezoelectric element PZ-Z1 may decrease, potentially leading to deterioration of the piezoelectric element PZ-Z1.

[0104] In contrast, in the piezoelectric body Qm according to the first embodiment, in the region other than the piezoelectric body driving region RZK1 that constitutes the piezoelectric element PZ1, i.e., in the piezoelectric body outer edge region RZG1, the width of the same potential region in the X-axis direction is longer than the width of the different potential region in the X-axis direction. Therefore, according to the first embodiment, it is possible to suppress displacement of the piezoelectric body Qm in the Z-axis direction due to the voltage applied to the piezoelectric body Qm, compared to Reference Example 1. As a result, according to the first embodiment, it is possible to suppress deterioration in the sealing performance of the piezoelectric element PZ1 by the sealing substrate 25, compared to Reference Example 1.

[0105] Furthermore, in the liquid ejection head 1Z according to Reference Example 1, in the partial region RZ11, a parasitic capacitance occurs between the auxiliary layer HC-Z connected to the lower surface of the piezoelectric element QmZ and the common electrode QB-Z1 connected to the upper surface of the piezoelectric element QmZ. Therefore, in Reference Example 1, for example, when the potential of the common electrode QB-Z1 deviates from the reference potential VBS, charging and discharging of the parasitic capacitance generated in the partial region RZ11 may occur, causing the partial region RZ11 to generate heat. As a result, in Reference Example 1, the heat generated in the partial region RZ11 may affect the ejection characteristics of the liquid ejection head 1Z, such as by causing the operating characteristics of the piezoelectric element PZ-Z1 to fluctuate.

[0106] In contrast, in the liquid ejection head 1 according to the first embodiment, the potential of the conductor connected to the lower surface of the piezoelectric body Qm and the potential of the conductor connected to the upper surface of the piezoelectric body Qm are set to be substantially the same in the piezoelectric body outer edge region RG1. Therefore, in the first embodiment, compared to Reference Example 1, it is possible to reduce the possibility of parasitic capacitance occurring between the lower and upper surfaces of the piezoelectric body Qm in the piezoelectric body outer edge region RG1. As a result, in the first embodiment, it is possible to suppress heat generation in the piezoelectric body outer edge region RG1 compared to Reference Example 1.

[0107] Furthermore, in the liquid ejection head 1Z according to Reference Example 1, the piezoelectric body extension region RZ1 of the piezoelectric body QmZ includes a piezoelectric body driving region RZK1 located above the pressure chamber CV1 and constituting the piezoelectric element PZ-Z1, a piezoelectric body outer edge region RZG1 located below the wall WB1, and a piezoelectric body connection region RZM1 connecting the piezoelectric body driving region RZK1 and the piezoelectric body outer edge region RZG1, and extends widely in the X-axis direction from the lower part of the wall WA1 to the lower part of the wall WB1. In Reference Example 1, the piezoelectric body extension region RZ1 includes the piezoelectric body connection region RZM1 and has a wide area. Therefore, compared to an embodiment that does not include the piezoelectric body connection region RZM1, for example, when the actuator substrate AT-Z having the piezoelectric structure 27Z including the piezoelectric body QmZ and the sealing substrate 25 are bonded together with the adhesive layer 50, there is a higher possibility that foreign matter will be mixed in between the actuator substrate AT-Z and the sealing substrate 25. If foreign matter gets mixed in between the actuator substrate AT-Z and the sealing substrate 25, when the piezoelectric element PZ-Z1 having the piezoelectric body QmZ included in the actuator substrate AT-Z is driven by the drive signal Com, the influence of the foreign matter may cause the piezoelectric element PZ-Z1 to be driven in a manner different from that specified by the drive signal Com. In other words, if foreign matter gets mixed in between the actuator substrate AT-Z and the sealing substrate 25, the influence of the foreign matter may cause a decrease in the ink ejection performance from the liquid ejection head 1Z.

[0108] In contrast, in the first embodiment, the piezoelectric body driving region RK1 and the piezoelectric body outer edge region RG1 included in the piezoelectric body Qm are spaced apart from each other. That is, according to the first embodiment, the piezoelectric body driving region RK1 located above the pressure chamber CV1 and constituting the piezoelectric element PZ1, and the piezoelectric body outer edge region RG1 located below the wall WB1, are spaced apart from each other. Therefore, according to the first embodiment, the area of the piezoelectric body Qm as viewed in the Z-axis direction can be reduced compared to Reference Example 1. As a result, according to the first embodiment, it is possible to reduce the possibility of foreign matter being mixed between the actuator substrate AT and the sealing substrate 25 compared to Reference Example 1, and it is possible to reduce the possibility of the ink ejection performance from the liquid ejection head 1 being degraded due to the influence of foreign matter mixed between the actuator substrate AT and the sealing substrate 25.

[0109] Furthermore, in the liquid ejection head 1Z according to Reference Example 1, when the piezoelectric element PZ-Z1 is driven by the drive signal Com and the piezoelectric driving region RZK1 of the piezoelectric extension region RZ1 of the piezoelectric element QmZ vibrates, the vibrations generated in the piezoelectric driving region RZK1 are transmitted to the piezoelectric outer edge region RZG1 via the piezoelectric connection region RZM1. In Reference Example 1, the vibrations transmitted to the piezoelectric outer edge region RZG1 displace the sealing substrate 25 located above the piezoelectric outer edge region RZG1 and the pressure chamber substrate 23 located below the piezoelectric outer edge region RZG1. When the sealing substrate 25 is displaced, the sealing performance of the sealing substrate 25 for the piezoelectric element PZ-Z1 deteriorates. Furthermore, when the pressure chamber substrate 23 is displaced, the volume and shape of the pressure chamber CV1 change, thereby deteriorating the ink ejection performance from the liquid ejection head 1Z. Thus, according to Reference Example 1, there is a high possibility that vibrations transmitted from the piezoelectric driving region RZK1 via the piezoelectric connection region RZM1 to the piezoelectric outer edge region RZG1 will result in a decrease in the sealing ability of the piezoelectric element PZ-Z1 and a decrease in the ejection performance of the liquid ejection head 1Z.

[0110] In contrast to this, in the first embodiment, as described above, the piezoelectric body driving region RK1 and the piezoelectric body outer edge region RG1 are spaced apart, and therefore the degree to which vibrations generated in the piezoelectric body driving region RK1 when the piezoelectric element PZ1 is driven by the drive signal Com are transmitted to the piezoelectric body outer edge region RG1 can be reduced compared to Reference Example 1. Therefore, according to the first embodiment, it is possible to reduce deterioration in the sealing performance for the piezoelectric element PZ1 and also reduce deterioration in the ejection performance of the liquid ejection head 1 compared to Reference Example 1.

[0111] Fig. 9 is a cross-sectional view of the liquid ejection head 1W according to Reference Example 2 when viewed in the Y2 direction. Fig. 10 is a plan view of the actuator substrate AT-W provided in the liquid ejection head 1W when viewed in the Z1 direction.

[0112] 9 and 10, the liquid ejection head 1W differs from the liquid ejection head 1 according to the first embodiment in that it includes a piezoelectric structure 27W including a piezoelectric element QmW instead of the piezoelectric structure 27 including the piezoelectric element Qm. The piezoelectric element QmW differs from the piezoelectric element Qm according to the first embodiment in that it does not include a piezoelectric element outer edge region RG1 corresponding to the nozzle row Ln1. In other words, the piezoelectric element QmW includes a piezoelectric element driving region RK1 and a piezoelectric element central region RP1 corresponding to the nozzle row Ln1.

[0113] Liquid ejection head 1W also differs from liquid ejection head 1 according to the first embodiment in that it includes a piezoelectric element PZ-W1 instead of piezoelectric element PZ1. Piezoelectric element PZ-W1 also differs from piezoelectric element PZ1 according to the first embodiment in that it includes a piezoelectric body QmW instead of piezoelectric body Qm. Piezoelectric structure 27W also differs from piezoelectric structure 27 according to the first embodiment in that it includes an auxiliary electrode LB-W1 laminated on piezoelectric body QmZ instead of auxiliary electrode LB1. Piezoelectric structure 27W also differs from piezoelectric structure 27 according to the first embodiment in that it does not include auxiliary electrodes Hx11, Hx41, and HC1.

[0114] It is assumed that the liquid ejection head 1W has a configuration that is substantially plane-symmetrical with respect to a plane having the X-axis direction as the normal direction.

[0115] As described above, in the liquid ejection head 1W according to Reference Example 2, the piezoelectric element QmW has a piezoelectric element driving region RK1 that is smaller in area than the piezoelectric element extending region RZ1 according to Reference Example 1. Therefore, according to Reference Example 2, it is possible to reduce the possibility of foreign matter getting mixed in between the actuator substrate AT-W and the sealing substrate 25 when bonding the actuator substrate AT-W and the sealing substrate 25 with the adhesive layer 50, compared to an embodiment in which the liquid ejection head 1Z is provided with a piezoelectric element QmZ that has a piezoelectric element extending region RZ1 with a larger area, as in Reference Example 1.

[0116] 9, in the piezoelectric structure 27W according to Reference Example 2, in addition to the adhesive layer 50 and the individual electrode QC1, the piezoelectric element QmW, the individual wiring LC1, and the auxiliary electrode LA1 are provided below the wall WA1, while only the adhesive layer 50 and the auxiliary layer Hy1 are provided below the wall WB1. That is, in Reference Example 2, the thickness of the adhesive layer 50 below the wall WA1 is different from the thickness of the adhesive layer 50 below the wall WB1. Therefore, compared to Reference Example 1, Reference Example 2 has weaker adhesion between the piezoelectric structure 27W and the sealing substrate 25, and the strength of the actuator chip including the actuator substrate AT-W and the sealing substrate 25 is lower.

[0117] In contrast, in the first embodiment, the piezoelectric element Qm includes a piezoelectric element outer edge region RG1 in addition to a piezoelectric element driving region RK1. Furthermore, in the first embodiment, individual wiring LC1 and auxiliary electrodes LA1 are provided on the piezoelectric element driving region RK1, and auxiliary electrodes LB1 and auxiliary layers LD1 are provided on the piezoelectric element outer edge region RG1. Therefore, in the first embodiment, the thickness of the adhesive layer 50 below the wall WA1 and the thickness of the adhesive layer 50 below the wall WB1 can be made substantially the same. Therefore, compared to Reference Example 2, the first embodiment can improve the adhesion between the piezoelectric structure 27 and the sealing substrate 25, thereby increasing the strength of the actuator chip AC including the actuator substrate AT and the sealing substrate 25.

[0118] As described above, according to the first embodiment, it is possible to achieve both reduction in the possibility of displacement of the piezoelectric body Qm, reduction in the possibility of heat generation in the piezoelectric body Qm, reduction in the possibility of foreign matter mixing between the actuator substrate AT and the sealing substrate 25, and reduction in the possibility of deterioration of the sealing performance of the piezoelectric element PZ1 by the sealing substrate 25, and ensuring the strength of the actuator chip AC.

[0119] <<A.5. Conclusion of the First Embodiment>> As described above, the liquid ejection head 1 according to the first embodiment includes a pressure chamber substrate 23 provided with a pressure chamber CV1 extending in the X1 direction, a piezoelectric element PZ1 disposed at a position in the Z2 direction when viewed from the pressure chamber CV1 and including a piezoelectric body Qm, a common electrode QB1, and an individual electrode QC1, and a sealing substrate 25 provided with a recess OB1 for accommodating the piezoelectric element PZ1 and disposed at a position in the Z2 direction when viewed from the piezoelectric element PZ1. The piezoelectric body Qm has a piezoelectric drive region RK1 that overlaps the pressure chamber CV1 and a piezoelectric outer edge region RG1 that overlaps a wall WB1 of two walls of the recess OB1 in the X1 direction when the liquid ejection head 1 is viewed in a plan view with respect to the direction perpendicular to the sealing substrate 25. The piezoelectric drive region RK1 and the piezoelectric outer edge region RG1 are provided separately. Among the piezoelectric outer edge regions RG1, the width in the X1 direction of the potential identical region where the potentials of the upper and lower portions of the piezoelectric body Qm are substantially the same is longer than the width in the X1 direction of the potential different region where the potentials of the upper and lower portions of the piezoelectric body Qm are not substantially the same.

[0120] Thus, according to the liquid ejection head 1 of the first embodiment, in the piezoelectric outer edge region RG1, the width in the X1 direction of the same potential region is longer than the width in the X1 direction of the different potential region, and therefore, displacement of the piezoelectric body Qm in the piezoelectric outer edge region RG1 can be suppressed compared to an embodiment in which the width in the X1 direction of the same potential region is shorter than the width in the X1 direction of the different potential region. Therefore, according to the first embodiment, it is possible to suppress fluctuations in the relative positional relationship between the piezoelectric body Qm and the sealing substrate 25 compared to an embodiment in which the width in the X1 direction of the same potential region is shorter than the width in the X1 direction of the different potential region, and this makes it possible to suppress deterioration in the sealing performance of the piezoelectric element PZ1 by the sealing substrate 25.

[0121] Furthermore, according to the liquid ejection head 1 of the first embodiment, the piezoelectric body driving region RK1 and the piezoelectric body outer edge region RG1 are spaced apart, which reduces the possibility of foreign matter entering between the piezoelectric body Qm and the sealing substrate 25 compared to an embodiment in which the piezoelectric body driving region RK1 and the piezoelectric body outer edge region RG1 are continuously provided, and also reduces the possibility that, even if foreign matter does enter between the piezoelectric body Qm and the sealing substrate 25, the relative positional relationship between the piezoelectric body Qm and the sealing substrate 25 will fluctuate due to the foreign matter. Therefore, according to the first embodiment, it is possible to suppress fluctuations in ejection characteristics due to foreign matter entering between the piezoelectric body Qm and the sealing substrate 25 compared to an embodiment in which the piezoelectric body driving region RK1 and the piezoelectric body outer edge region RG1 are continuously provided. Furthermore, according to the first embodiment, compared to the aspect in which the piezoelectric driving region RK1 and the piezoelectric outer edge region RG1 are continuously arranged, it is possible to suppress fluctuations in the relative positional relationship between the piezoelectric body Qm and the sealing substrate 25 due to foreign matter mixed between the piezoelectric body Qm and the sealing substrate 25, and to suppress fluctuations in the ejection characteristics due to fluctuations in the relative positional relationship between the piezoelectric body Qm and the sealing substrate 25.

[0122] Furthermore, according to the liquid ejection head 1 of the first embodiment, the piezoelectric body driving region RK1 and the piezoelectric body outer edge region RG1 are spaced apart from each other. This reduces the degree to which vibrations generated in the piezoelectric body driving region RK1 when the piezoelectric element PZ1 is driven by the drive signal Com are transmitted to the piezoelectric body outer edge region RG1, compared to an embodiment in which the piezoelectric body driving region RK1 and the piezoelectric body outer edge region RG1 are continuously provided. Therefore, according to the first embodiment, compared to an embodiment in which the piezoelectric body driving region RK1 and the piezoelectric body outer edge region RG1 are continuously provided, the possibility of displacement of the pressure chamber substrate 23 due to vibrations in the piezoelectric body outer edge region RG1 is reduced, and the possibility of fluctuations in the volume and shape of the pressure chamber CV1 due to displacement of the pressure chamber substrate 23 is reduced. As a result, according to the first embodiment, it is possible to suppress fluctuations in the ejection performance of the liquid ejection head 1 due to fluctuations in the volume and shape of the pressure chamber CV1, compared to an embodiment in which the piezoelectric body driving region RK1 and the piezoelectric body outer edge region RG1 are continuously provided.

[0123] In the first embodiment, the X1 direction is an example of the "first direction," the Z2 direction is an example of the "upper side," the common electrode QB is an example of the "upper electrode," the individual electrode QC is an example of the "lower electrode," the sealing substrate 25 is an example of the "sealing plate," the piezoelectric driving region RK1 is an example of the "first region," the piezoelectric outer edge region RG1 is an example of the "second region," the wall WB1 is an example of "one of the two walls of the first recess," the same potential region of the piezoelectric outer edge region RG1 is an example of the "first potential region," and the different potential region of the piezoelectric outer edge region RG1 is an example of the "second potential region."

[0124] Furthermore, in the liquid ejection head 1 of the first embodiment, the upper element connected to the piezoelectric body Qm at a position in the Z2 direction as viewed from the piezoelectric body outer edge region RG1 includes an auxiliary layer Hy1 that is not electrically connected to the common electrode QB1 and the individual electrode QC1, and the lower element connected to the piezoelectric body Qm at a position in the Z1 direction as viewed from the piezoelectric body outer edge region RG1 includes an auxiliary layer HC21 that overlaps with the auxiliary layer Hy1 when the liquid ejection head 1 is viewed in a plane and is not electrically connected to the common electrode QB1 and the individual electrode QC1.

[0125] Therefore, in the liquid ejection head 1 according to the first embodiment, in the piezoelectric outer edge region RG1, the upper and lower portions of the piezoelectric body Qm can be made substantially the same potential, thereby suppressing the displacement of the piezoelectric body Qm in the piezoelectric outer edge region RG1.

[0126] In the first embodiment, the auxiliary layer Hy1 is an example of the "first upper element", and the auxiliary layer HC21 is an example of the "first lower element".

[0127] Further, in the liquid ejection head 1 according to the first embodiment, the upper element connected to the piezoelectric body Qm at a position in the Z2 direction as viewed from the piezoelectric outer edge region RG1 includes an auxiliary electrode Hx41 electrically connected to the common electrode QB1, and the lower element connected to the piezoelectric body Qm at a position in the Z1 direction as viewed from the piezoelectric outer edge region RG1 includes an auxiliary electrode HC11 that overlaps with the auxiliary electrode Hx41 when the liquid ejection head 1 is viewed in plan and is electrically connected to the common electrode QB1.

[0128] Therefore, in the liquid ejection head 1 according to the first embodiment, in the piezoelectric outer edge region RG1, the upper and lower portions of the piezoelectric body Qm can be made substantially the same potential, thereby suppressing the displacement of the piezoelectric body Qm in the piezoelectric outer edge region RG1.

[0129] In the first embodiment, the common electrode QB1 is an example of "one of the upper electrode and the lower electrode", the auxiliary electrode Hx41 is an example of the "second upper element", and the auxiliary electrode HC11 is an example of the "second lower element".

[0130] <<B. Second Embodiment>> Hereinafter, the liquid ejection device according to the second embodiment will be described while referring to FIGS. 11 and 12. For elements whose operations and functions are the same as those in the first embodiment in each of the embodiments illustrated below, the reference numerals used in the description of the first embodiment are reused, and the detailed description of each is appropriately omitted.

[0131] <<B.1. Outline of the Liquid Ejection Head According to the Second Embodiment>> The liquid ejection device according to the second embodiment differs from the liquid ejection device 100 according to the first embodiment in that it includes a liquid ejection head 1B instead of the liquid ejection head 1.

[0132] Fig. 11 is a cross-sectional view of the liquid ejection head 1B according to the second embodiment when viewed in the Y2 direction. Fig. 12 is a plan view of the actuator substrate AT-B provided in the liquid ejection head 1B when viewed in the Z1 direction.

[0133] 11 and 12, the liquid ejection head 1B differs from the liquid ejection head 1 according to the first embodiment in that it includes a piezoelectric structure 27B including a piezoelectric element QmB instead of the piezoelectric structure 27 including the piezoelectric element Qm. The piezoelectric element QmB differs from the piezoelectric element Qm according to the first embodiment in that it further includes a piezoelectric element support region RS1 in addition to a piezoelectric element driving region RK1, a piezoelectric element outer edge region RG1, and a piezoelectric element central region RP1 corresponding to the nozzle row Ln1.

[0134] Here, as shown in Figures 11 and 12, the piezoelectric support region RS1 is located between the piezoelectric driving region RK1 and the piezoelectric outer edge region RG1 in the X-axis direction, and is spaced apart from the piezoelectric driving region RK1 and the piezoelectric outer edge region RG1.

[0135] Furthermore, the piezoelectric body support region RS1 is provided at a position where at least a part of the piezoelectric body support region RS1 and at least a part of the wall WB1 overlap when the liquid ejection head 1B is viewed in a plan view in the Z1 direction. In the following description, the region including the end portion of the wall WB1 in the X-axis direction located in the X1 direction will be referred to as the end portion Wt1, and the region including the end portion located in the X2 direction will be referred to as the end portion Wt2. In the second embodiment, the piezoelectric support region RS1 is provided at a position where at least a portion of the piezoelectric support region RS1 overlaps with at least a portion of the end portion Wt2 when the liquid ejection head 1B is viewed in a plane in the Z1 direction. Furthermore, the piezoelectric outer edge region RG1 is provided at a position where at least a portion of the piezoelectric outer edge region RG1 overlaps with at least a portion of the end portion Wt1 when the liquid ejection head 1B is viewed in a plane in the Z1 direction. However, the present invention is not limited to this configuration. The piezoelectric support region RS1 may be provided at a position where the piezoelectric support region RS1 does not overlap with the end portion Wt2 when the liquid ejection head 1B is viewed in a plane in the Z1 direction. Furthermore, the piezoelectric outer edge region RG1 may be provided at a position where the piezoelectric outer edge region RG1 and the end region Wt1 do not overlap when the liquid ejection head 1B is viewed in a plan view in the Z1 direction.

[0136] In the second embodiment, as an example, it is assumed that the piezoelectric body support region RS1 is provided at a position where at least a portion of the piezoelectric body support region RS1 and at least a portion of the throttle portion SB1 overlap when the liquid ejection head 1B is viewed in a plane in the Z1 direction. However, the present invention is not limited to this aspect. The piezoelectric body support region RS1 may be provided at a position where the piezoelectric body support region RS1 and the throttle portion SB1 do not overlap when the liquid ejection head 1B is viewed in a plane in the Z1 direction.

[0137] In the second embodiment, as an example, it is assumed that the piezoelectric body QmB is provided so that the width of the piezoelectric body driving region RK1 in the X-axis direction is greater than the width of the piezoelectric body outer edge region RG1 in the X-axis direction, and the width of the piezoelectric body outer edge region RG1 in the X-axis direction is greater than the width of the piezoelectric body support region RS1 in the X-axis direction. However, the width of the piezoelectric body outer edge region RG1 in the X-axis direction may be less than or equal to the width of the piezoelectric body support region RS1 in the X-axis direction.

[0138] 12, the second embodiment is assumed to have an extending portion RSy1 that extends in the X-axis direction at a position in the Y1 direction as viewed from the plurality of pressure chambers CV1 of the liquid ejection head 1B, and an extending portion RSy2 that extends in the X-axis direction at a position in the Y2 direction as viewed from the plurality of pressure chambers CV1 of the liquid ejection head 1B. In other words, the second embodiment is assumed to have a case in which the piezoelectric support region RS1 is provided so as to surround the plurality of pressure chambers CV1 of the liquid ejection head 1B.

[0139] Liquid ejection head 1B also differs from liquid ejection head 1 according to the first embodiment in that it includes a piezoelectric element PZ-B1 instead of piezoelectric element PZ1. Piezoelectric element PZ-B1 also differs from piezoelectric element PZ1 according to the first embodiment in that it includes a piezoelectric body QmB instead of piezoelectric body Qm. Piezoelectric structure 27B also differs from piezoelectric structure 27 according to the first embodiment in that it includes an auxiliary electrode Hx21 laminated on piezoelectric body support region RS1 and an auxiliary electrode Hx31 laminated on auxiliary electrode HC11. Piezoelectric structure 27B also differs from piezoelectric structure 27 according to the first embodiment in that it includes an auxiliary electrode LB-B1 instead of auxiliary electrode LB1. The auxiliary electrode LB-B1 is laminated on the common electrode QB1, the piezoelectric element QmB, the auxiliary electrode Hx11, the auxiliary electrode Hx21 provided on the piezoelectric element support region RS1, the auxiliary electrode Hx31, the auxiliary electrode Hx41 provided on the piezoelectric element outer edge region RG1, and the auxiliary electrode HC11. Note that the auxiliary electrode LB-B1 only needs to be laminated on at least a portion of the common electrode QB1 provided on the piezoelectric element drive region RK1 and at least a portion of the auxiliary electrode Hx21 provided on the piezoelectric element support region RS1. Like the auxiliary electrode LB1, the auxiliary electrode LB-B1 is formed of a conductive material such as gold (Au).

[0140] It is assumed that the liquid ejection head 1B has a configuration that is approximately symmetrical with respect to a plane normal to the X-axis direction. Specifically, the liquid ejection head 1B corresponds to the nozzle row Ln2 and includes a piezoelectric support region RS2 that is an element symmetrical to the piezoelectric support region RS1, a piezoelectric element PZ-B2 that is an element symmetrical to the piezoelectric element PZ-B1, and an auxiliary electrode LB-B2 that is an element symmetrical to the auxiliary electrode LB-B1.

[0141] The voltage applied to the piezoelectric body QmB will be considered below.

[0142] 11, in partial region RG11, a voltage VG1 (=VBS-VBS=0) is applied to the piezoelectric body QmB, in partial region RG12, a voltage VG2 (=VBS-V0>0) is applied to the piezoelectric body QmB, in partial region RG13, a voltage VG3 (=V0-V0=0) is applied to the piezoelectric body QmB, and in partial region RG14, a voltage VG4 (=V0-V0=0) is applied to the piezoelectric body QmB. That is, in partial region RG11, the electric potentials at the top and bottom of the piezoelectric body QmB are approximately the same, in partial region RG12, the electric potentials at the top and bottom of the piezoelectric body QmB are different, in partial region RG13, the electric potentials at the top and bottom of the piezoelectric body QmB are approximately the same, and in partial region RG14, the electric potentials at the top and bottom of the piezoelectric body QmB are approximately the same.

[0143] As shown in FIG. 11, the voltage applied to the piezoelectric body QmB in the piezoelectric body support region RS1 is referred to as voltage VS. As described above, in the piezoelectric body support region RS1, the auxiliary electrode HC11 connected to the lower surface of the piezoelectric body QmB is electrically connected to the auxiliary electrode LB-B1 and set to the reference potential VBS. In the piezoelectric body support region RS1, the auxiliary electrode Hx21 connected to the upper surface of the piezoelectric body QmB is electrically connected to the auxiliary electrode LB-B1 and set to the reference potential VBS. Therefore, the voltage VS becomes "VS = VBS - VBS = 0", and even considering errors such as noise, the voltage VS is approximately the same as "0V". That is, in the piezoelectric body support region RS1, the potentials of the upper and lower parts of the piezoelectric body QmZ are substantially the same. In other words, in the second embodiment, the piezoelectric body support region RS1 corresponds to the "equal potential region".

[0144] In the second embodiment, an aspect in which the piezoelectric body support region RS1 is composed only of the equal potential region and does not include the potential difference region is illustrated and described, but the present invention is not limited to such an aspect. The piezoelectric body support region RS1 may include a potential difference region. In this case, it is preferable that the width in the X1 direction of the equal potential region in the piezoelectric body support region RS1 is longer than the width in the X1 direction of the potential difference region in the piezoelectric body support region RS1.

[0145] <<B.2. Conclusion of the Second Embodiment>> As described above, the liquid ejection head 1B according to the second embodiment is a liquid ejection head 1 including: a pressure chamber substrate 23 in which a pressure chamber CV1 extending in the X1 direction is provided; a piezoelectric element PZ1 that is arranged in the Z2 direction as viewed from the pressure chamber CV1, and that includes a piezoelectric body Qm, a common electrode QB1, and an individual electrode QC1; and a sealing substrate 25 that is arranged in the Z2 direction as viewed from the piezoelectric element PZ1, and that has a recess OB1 that houses the piezoelectric element PZ1. When the liquid ejection head 1 is viewed in a plane perpendicular to the sealing substrate 25, the piezoelectric body Qm is divided into a piezoelectric body driving region RK1 that overlaps with the pressure chamber CV1; a piezoelectric body outer edge region RG1 that overlaps with the wall WB1 of the two walls that the recess OB1 has in the X1 direction; The piezoelectric element may have a piezoelectric support region RS1 overlapping with WB1, and the piezoelectric driving region RK1 and the piezoelectric outer edge region RG1 are spaced apart, and the piezoelectric support region RS1 is located between the piezoelectric driving region RK1 and the piezoelectric outer edge region RG1, and the width in the X1 direction of the same potential region in the piezoelectric outer edge region RG1, where the potentials at the top and bottom of the piezoelectric element Qm are approximately the same, is longer than the width in the X1 direction of the different potential region in the X1 direction where the potentials at the top and bottom of the piezoelectric element Qm are not approximately the same, and the width in the X1 direction of the same potential region in the piezoelectric support region RS1, where the potentials at the top and bottom of the piezoelectric element Qm are approximately the same, is longer than the width in the X1 direction of the different potential region in the X1 direction where the potentials at the top and bottom of the piezoelectric element Qm are not approximately the same.

[0146] As described above, in the liquid ejection head 1B according to the second embodiment, in the piezoelectric support region RS1, the width in the X1 direction of the same potential region is longer than the width in the X1 direction of the different potential region, and therefore, displacement of the piezoelectric Qm in the piezoelectric support region RS1 can be suppressed compared to an embodiment in which the width in the X1 direction of the same potential region is shorter than the width in the X1 direction of the different potential region. Therefore, according to the second embodiment, it is possible to suppress fluctuations in the relative positional relationship between the piezoelectric QmB and the sealing substrate 25 compared to an embodiment in which the width in the X1 direction of the same potential region is shorter than the width in the X1 direction of the different potential region, and this makes it possible to suppress deterioration in the sealing performance of the sealing substrate 25 for the piezoelectric element PZ-B1.

[0147] Furthermore, according to the liquid ejection head 1B of the second embodiment, the piezoelectric body driving region RK1 and the piezoelectric body outer edge region RG1 are spaced apart, which reduces the possibility of foreign matter entering between the piezoelectric body QmB and the sealing substrate 25 compared to an embodiment in which the piezoelectric body driving region RK1 and the piezoelectric body outer edge region RG1 are continuously provided, and even if foreign matter does enter between the piezoelectric body QmB and the sealing substrate 25, it reduces the possibility that the foreign matter will cause a change in the relative positional relationship between the piezoelectric body QmB and the sealing substrate 25. Therefore, according to the second embodiment, as with the first embodiment, it is possible to suppress changes in ejection characteristics caused by foreign matter entering between the piezoelectric body QmB and the sealing substrate 25 compared to an embodiment in which the piezoelectric body driving region RK1 and the piezoelectric body outer edge region RG1 are continuously provided.

[0148] Furthermore, according to the liquid ejection head 1B of the second embodiment, the piezoelectric body driving region RK1 and the piezoelectric body outer edge region RG1 are provided at a distance from each other, and therefore, compared to an embodiment in which the piezoelectric body driving region RK1 and the piezoelectric body outer edge region RG1 are provided continuously, the degree to which vibrations generated in the piezoelectric body driving region RK1 when the piezoelectric element PZ-B1 is driven by the drive signal Com are transmitted to the piezoelectric body outer edge region RG1 can be reduced. Therefore, according to the second embodiment, as with the first embodiment, compared to an embodiment in which the piezoelectric body driving region RK1 and the piezoelectric body outer edge region RG1 are provided continuously, the possibility of displacement of the pressure chamber substrate 23 due to vibrations of the piezoelectric body outer edge region RG1 is reduced, and the possibility of fluctuations in the volume and shape of the pressure chamber CV1 due to displacement of the pressure chamber substrate 23 can be reduced.

[0149] Furthermore, according to the liquid ejection head 1B of the second embodiment, since the piezoelectric body QmB has a piezoelectric body support region RS1, pressure is more easily transmitted from the piezoelectric body QmB to the sealing substrate 25 in the process of bonding the actuator substrate AT-B including the piezoelectric body QmB to the sealing substrate 25, or in the process of bonding the actuator chip including the actuator substrate AT-B and the sealing substrate 25 to other components such as the communicating plate 22, compared to an embodiment that does not have a piezoelectric body support region RS1, thereby enabling reliable bonding to be achieved in each bonding process.

[0150] In the second embodiment, the piezoelectric body support region RS1 is an example of the "third region", the region with the same potential in the piezoelectric body support region RS1 is an example of the "third potential region", and the region with different potentials in the piezoelectric outer edge region RG1 is an example of the "fourth potential region".

[0151] <<C. Modified Example>> Each of the embodiments exemplified above can be variously modified. Specific modification modes are exemplified below. Two or more modes arbitrarily selected from the following examples can be appropriately combined within a range where they do not conflict with each other.

[0152] <Modified Example 1> In the first and second embodiments described above, the mode in which the piezoelectric outer edge region RG1 includes the partial region RG12 has been exemplified and described, but the present invention is not limited to such a mode. The piezoelectric outer edge region RG1 may be configured without including the partial region RG12. For example, when the liquid ejection head 1 (or the liquid ejection head 1B) is viewed in plan view, the auxiliary electrode Hx41 and the auxiliary electrode HC11 may be provided such that the end portion of the auxiliary electrode Hx41 in the X1 direction and the end portion of the auxiliary electrode HC11 in the X1 direction are substantially at the same position in the X-axis direction.

[0153] That is, the liquid ejection head according to Modified Example 1 is characterized in that the piezoelectric outer edge region RG1 is configured not to include a region with different potentials.

[0154] Therefore, in the liquid ejection head 1 according to Modified Example 1, it is possible to make the upper and lower portions of the piezoelectric body Qm (or the piezoelectric body QmB) substantially at the same potential throughout the piezoelectric outer edge region RG1, and thereby it is possible to suppress the displacement of the piezoelectric body Qm (or the piezoelectric body QmB) in the piezoelectric outer edge region RG1.

[0155] <Modified Example 2> In the first and second embodiments and Modification 1 described above, an example was described in which the individual electrode QC1 is disposed in the Z1 direction as viewed from the piezoelectric body Qm, and the common electrode QB1 is disposed in the Z2 direction as viewed from the piezoelectric body Qm. However, the present invention is not limited to such an example. The individual electrode QC1 may be disposed in the Z2 direction as viewed from the piezoelectric body Qm, and the common electrode QB1 may be disposed in the Z1 direction as viewed from the piezoelectric body Qm. In this case, it is sufficient that the individual electrode QC1 is provided corresponding to each of the multiple nozzles N1. Furthermore, in this case, the auxiliary electrodes LA1, LB1, and HC11 may be provided corresponding to each of the multiple nozzles N1 and electrically connected to the individual electrode QC1.

[0156] <Variation 3> In the above-described first and second embodiments and modifications 1 and 2, a serial-type liquid ejection device in which the storage case 921 mounting the liquid ejection head 1 or 1B is moved back and forth in the X-axis direction is exemplified, but the present invention is not limited to such an embodiment. The liquid ejection device may also be a line-type liquid ejection device in which multiple nozzles N are distributed across the entire width of the medium PP.

[0157] <Variation 4> The liquid ejection devices exemplified in the first and second embodiments and modifications 1 to 3 described above can be employed in various devices such as facsimile machines and copiers, as well as devices dedicated to printing. However, the use of the liquid ejection device of the present invention is not limited to printing. For example, a liquid ejection device that ejects a solution of a color material is used as a manufacturing device for forming color filters for liquid crystal display devices. Furthermore, a liquid ejection device that ejects a solution of a conductive material is used as a manufacturing device for forming wiring and electrodes for wiring substrates. [Explanation of symbols]

[0158] 1...liquid ejection head, 21...nozzle substrate, 22...communicating plate, 23...pressure chamber substrate, 24...vibration plate, 25...sealing substrate, 26...flow path forming substrate, 27...piezoelectric structure, CV1...pressure chamber, OB1...recess, PZ1...piezoelectric element, Qm...piezoelectric body, RG1...outer edge region of piezoelectric body, RG11...partial region, RG12...partial region, RG13...partial region, RG14...partial region, RK1...piezoelectric body driving region, WA1...wall, WA2...wall.

Claims

1. a pressure chamber substrate provided with pressure chambers extending in a first direction; a piezoelectric element disposed above the pressure chamber and including a piezoelectric body, an upper electrode, and a lower electrode; a sealing plate having a recess for accommodating the piezoelectric element and disposed above the piezoelectric element; A liquid ejection head comprising: the piezoelectric body has a first region that overlaps with the pressure chamber when the liquid ejection head is viewed in a plan view in the vertical direction, and a second region that overlaps with one of two walls of the recess in the first direction, the first region and the second region are spaced apart from each other, In the second region, a width in the first direction of a first potential region in which the potentials of the upper and lower parts of the piezoelectric body are substantially the same is longer than a width in the first direction of a second potential region in which the potentials of the upper and lower parts of the piezoelectric body are not substantially the same. A liquid ejection head characterized by:

2. The second region is configured without including the second potential region.

2. The liquid ejection head according to claim 1, wherein the liquid ejection head comprises: a first electrode;

3. an upper element connected to the piezoelectric body in an upper portion of the second region includes a first upper element that is not electrically connected to the upper electrode and the lower electrode; a lower element connected to the piezoelectric body below the second region overlaps with the first upper element when the liquid ejection head is viewed from above, and includes a first lower element that is not electrically connected to the upper electrode and the lower electrode; 2. The liquid ejection head according to claim 1, wherein the liquid ejection head comprises: a first electrode;

4. an upper element connected to the piezoelectric body above the second region includes a second upper element electrically connected to one of the upper electrode and the lower electrode; a lower element connected to the piezoelectric body below the second region overlaps with the second upper element when the liquid ejection head is viewed from above, and includes a second lower element electrically connected to one of the upper electrode and the lower electrode; 2. The liquid ejection head according to claim 1, wherein the liquid ejection head comprises: a first electrode;

5. the piezoelectric body has a third region that overlaps with the one wall when the liquid ejection head is viewed from above, the third region is located between the first region and the second region and is spaced apart from the first region and the second region; a width in the first direction of a third potential region in which the potentials of the upper and lower parts of the piezoelectric body are substantially the same is greater than a width in the first direction of a fourth potential region in which the potentials of the upper and lower parts of the piezoelectric body are not substantially the same; 2. The liquid ejection head according to claim 1, wherein the liquid ejection head comprises: a first electrode;

6. A liquid ejection head according to any one of claims 1 to 5, A liquid ejection device characterized by:

Images