Liquid discharge head and liquid discharge apparatus

Abstract

To discharge ink from a nozzle efficiently while improving reliability of a liquid discharge head.SOLUTION: A liquid discharge head includes a diaphragm, a pressure chamber substrate laminated on a first surface of the diaphragm, and a piezoelectric element that includes first and second active portions disposed at mutually different positions and is laminated on a second surface of the diaphragm. If a lamination direction of the diaphragm and the piezoelectric element is defined as a first direction, a direction in which the first and second active portions are arranged when viewed in the first direction is defined as a second direction, and a direction orthogonal to the first and second directions is defined as a third direction, then at least a part of the first and second active portions overlaps a pressure chamber of the pressure chamber substrate when viewed in the first direction, and the piezoelectric element includes a first region in which both the first and second active portions are provided along the third direction, and a second region in which one of the first and second active portions is provided along the third direction and the other is not provided along the third direction.SELECTED DRAWING: Figure 14

Description

[Technical Field]

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

[0002] Liquid ejection devices, such as piezoelectric inkjet printers, generally have a liquid ejection head configured with a piezoelectric element disposed on a diaphragm that forms part of the wall of a pressure chamber that communicates with a nozzle. The pressure chamber contains a liquid, such as ink. The piezoelectric element deforms the diaphragm, expanding or contracting the volume of the pressure chamber, thereby ejecting the liquid from the nozzle.

[0003] The piezoelectric element of such a liquid ejection head may be divided into an active part that overlaps the center of the pressure chamber when viewed in the thickness direction of the vibration plate, and an active part that overlaps the end of the pressure chamber, as disclosed in Patent Document 1, for example. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-25225 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, the active parts corresponding to one pressure chamber are all equal in length and are arranged so that their longitudinal ends are aligned with one another. This causes excessive stress to be generated locally in the diaphragm near the longitudinal ends of these active parts, which may result in damage such as cracks in the diaphragm. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of a liquid ejection head according to the present disclosure includes a vibration plate having a first surface and a second surface facing in a direction opposite to the first surface, a pressure chamber substrate laminated on the first surface and having partition walls that define pressure chambers that communicate with nozzles that eject liquid, and a piezoelectric element laminated on the second surface, the piezoelectric element having a first active section and a second active section that deform when a voltage is applied and are disposed at different positions from each other, wherein the lamination direction of the vibration plate and the piezoelectric element is defined as a first direction, and the first active section and the second active section are aligned in the first direction. When the direction in which the first and second active parts are lined up is defined as a second direction, and a direction perpendicular to the first and second directions is defined as a third direction, at least a portion of each of the first active part and the second active part overlaps the pressure chamber when viewed in the first direction, and the piezoelectric element has a first region which is a region where both the first active part and the second active part are provided along the third direction, and a second region which is a region where one of the first active part and the second active part is provided along the third direction and the other is not provided along the third direction.

[0007] An aspect of a liquid ejection device according to the present disclosure includes a liquid ejection head according to the above-described aspect, and a drive signal generation unit that generates a first drive signal that drives the first active unit and a second drive signal that drives the second active unit. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a configuration diagram that schematically illustrates a liquid ejection device according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing the electrical configuration of the liquid ejection device according to the first embodiment. [Figure 3] FIG. 2 is an exploded perspective view of a head chip. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Figure 5] FIG. 2 is a plan view of a head chip. [Figure 6] FIG. 6 is a cross-sectional view taken along line BB in FIG. 5. [Figure 7] FIG. 2 is a diagram for explaining a switching circuit. [Figure 8]5A and 5B are diagrams for explaining a first drive signal and a second drive signal in the first embodiment. [Figure 9] FIG. 4 is a diagram for explaining a shrinking step in the first embodiment. [Figure 10] 5A and 5B are schematic diagrams for explaining deformation of a diaphragm due to a first drive signal. [Figure 11] 10A and 10B are schematic diagrams for explaining deformation of the diaphragm due to a second drive signal. [Figure 12] 3A and 3B are diagrams for explaining a first region, a second region, and a third region of the piezoelectric element in the first embodiment. [Figure 13] FIG. 3 is a cross-sectional view of a second region. [Figure 14] FIG. 3 is a cross-sectional view of a third region. [Figure 15] FIG. 10 is a diagram for explaining, as a comparative example, a configuration in which the longitudinal ends of the first region, the second region, and the third region are aligned. [Figure 16] FIG. 10 is a plan view of a head chip of a liquid ejection head according to a second embodiment. [Figure 17] FIG. 10 is a diagram illustrating a first region, a second region, and a third region of a liquid ejection head according to a third embodiment. [Figure 18] FIG. 10 is a diagram illustrating a first region, a second region, and a third region of a liquid ejection head according to a fourth embodiment. [Figure 19] FIG. 10 is a plan view of a head chip of a liquid ejection head according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Preferred embodiments of the present disclosure will be described below with reference to the accompanying drawings. Note that the dimensions and scale of each part in the drawings may differ from the actual dimensions and are shown schematically to facilitate understanding. Furthermore, the scope of the present disclosure is not limited to these embodiments unless otherwise specified in the following description to the effect that the present disclosure is limited.

[0010] For convenience, the following description will use the mutually intersecting X-axis, Y-axis, and Z-axis as appropriate. In the following description, one direction along the X-axis is the X1 direction, and the direction opposite the X1 direction is the X2 direction. Similarly, the opposite directions along the Y-axis are the Y1 direction and the Y2 direction. Furthermore, the opposite directions along the Z-axis are the Z1 direction and the Z2 direction. Viewing in the direction along the Z-axis is sometimes referred to as "planar view."

[0011] Here, the Z1 direction or Z2 direction is an example of a "first direction" and corresponds to the stacking direction of a vibration plate 51e and a piezoelectric element 51f (described later). The Y1 direction or Y2 direction is an example of a "second direction" and corresponds to the arrangement direction of an active part P1 and an active part P2 (described later). The X1 direction or X2 direction is an example of a "third direction" and is perpendicular to the stacking direction and the arrangement direction.

[0012] 1. First embodiment 1-1. Overall configuration of the liquid ejection device FIG. 1 is a schematic diagram illustrating a configuration of a liquid ejection device 100 according to a first embodiment. The liquid ejection device 100 is an inkjet printing device that ejects ink, an example of a liquid, as droplets onto a medium M. The medium M is typically printing paper. However, the medium M is not limited to printing paper, and may be a printing target made of any material, such as a resin film or fabric.

[0013] As shown in FIG. 1, the liquid ejection device 100 includes a liquid container 10, a control unit 20, a transport mechanism 30, a moving mechanism 40, and a liquid ejection head 50.

[0014] The liquid container 10 is a container that stores ink. Specific examples of the liquid container 10 include a cartridge that is detachable from the liquid ejection device 100, a bag-shaped ink pack made of flexible film, and an ink tank that can be refilled with ink. The type of ink stored in the liquid container 10 is arbitrary.

[0015] The control unit 20 includes a processing circuit such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array) and a storage circuit such as a semiconductor memory, and controls the operation of each element of the liquid ejection device 100.

[0016] The transport mechanism 30 transports the medium M in the Y2 direction under the control of the control unit 20. The movement mechanism 40 reciprocates the liquid ejection head 50 in the X1 direction and the X2 direction under the control of the control unit 20. In the example shown in FIG. 1, the movement mechanism 40 has a substantially box-shaped carriage 41 that houses the liquid ejection head 50, and an endless transport belt 42 to which the carriage 41 is fixed. Note that the number of liquid ejection heads 50 mounted on the carriage 41 is not limited to one, and may be multiple. In addition to the liquid ejection head 50, the carriage 41 may also be equipped with the aforementioned liquid container 10.

[0017] Under the control of the control unit 20, the liquid ejection head 50 ejects ink supplied from the liquid container 10 from each of the multiple nozzles in the Z2 direction toward the medium M. This ejection is performed in parallel with the transport of the medium M by the transport mechanism 30 and the reciprocating movement of the liquid ejection head 50 by the movement mechanism 40, so that an image is formed on the surface of the medium M using ink.

[0018] 1-2. Electrical configuration of the liquid ejection device 2 is a diagram showing the electrical configuration of the liquid ejection device 100 according to the first embodiment. The control unit 20 will be described below with reference to FIG. 2, but prior to this, the liquid ejection head 50 will be briefly described.

[0019] As shown in FIG. 2, the liquid ejection head 50 includes a head chip 51 and a switching circuit 52.

[0020] The head chip 51 has a plurality of piezoelectric elements 51f, which are appropriately driven to eject ink from the nozzles. Each piezoelectric element 51f has an active portion P1, which is an example of a "first active portion," an active portion P2, which is an example of a "second active portion," and an active portion P3, which is an example of a "third active portion." The active portion P1 is driven by a supply signal Vin-A. Meanwhile, the active portions P2 and P3 are each driven by a supply signal Vin-B. Details of the head chip 51 will be described later with reference to FIGS. 3 to 6.

[0021] Under the control of the control unit 20, the switching circuit 52 switches whether or not to supply the first drive signal Com-A and the second drive signal Com-B output from the control unit 20 to each of the multiple piezoelectric elements 51f of the head chip 51. The first drive signal Com-A is supplied to the active unit P1 as a supply signal Vin-A. The second drive signal Com-B is supplied to the active units P2 and P3 as a supply signal Vin-B. The active units P1, P2, and P3 will be described later with reference to FIG. 6. The switching circuit 52 will be described later in detail with reference to FIG. 7.

[0022] In the example shown in FIG. 2, the liquid ejection head 50 has one head chip 51, but the number is not limited to this, and the liquid ejection head 50 may have two or more head chips 51.

[0023] As shown in FIG. 2, the control unit 20 includes a control circuit 21, a memory circuit 22, a power supply circuit 23, and a drive signal generation circuit 24, which is an example of a "drive signal generation section."

[0024] The control circuit 21 has a function to control the operation of each part of the liquid ejection device 100 and a function to process various data. The control circuit 21 includes, for example, one or more processors such as a CPU (Central Processing Unit). Note that the control circuit 21 may include a programmable logic device such as an FPGA (Field-Programmable Gate Array) instead of or in addition to a CPU. Furthermore, when the control circuit 21 is made up of multiple processors, the multiple processors may be mounted on different boards or the like.

[0025] The memory circuit 22 stores various programs executed by the control circuit 21 and various data such as print data Img processed by the control circuit 21. The memory circuit 22 includes, for example, one or both of semiconductor memories: a volatile memory such as RAM (Random Access Memory) and a non-volatile memory such as ROM (Read Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), or PROM (Programmable ROM). The print data Img is supplied from an external device 200 such as a personal computer or digital camera. The memory circuit 22 may be configured as part of the control circuit 21.

[0026] The power supply circuit 23 receives power from a commercial power supply (not shown) and generates various predetermined potentials. The generated potentials are supplied to various parts of the liquid ejection device 100 as appropriate. For example, the power supply circuit 23 generates a power supply potential VHV and an offset potential VBS. The offset potential VBS is supplied to the liquid ejection head 50. The power supply potential VHV is also supplied to the drive signal generation circuit 24.

[0027] The drive signal generation circuit 24 generates the first drive signal Com-A and the second drive signal Com-B. Specifically, the drive signal generation circuit 24 includes, for example, a DA conversion circuit and an amplifier circuit. In the drive signal generation circuit 24, the DA conversion circuit converts the waveform specification signal dCom from the control circuit 21 from a digital signal to an analog signal, and the amplifier circuit amplifies the analog signal using the power supply potential VHV from the power supply circuit 23 to generate the first drive signal Com-A and the second drive signal Com-B, respectively. Among the waveforms included in the first drive signal Com-A, the signal having the waveform actually supplied to the active portion P1 of the piezoelectric element 51f is the aforementioned supply signal Vin-A. Among the waveforms included in the second drive signal Com-B, the signal having the waveform actually supplied to the active portion P2 or P3 of the piezoelectric element 51f is the aforementioned supply signal Vin-B. The waveform specification signal dCom is a digital signal that defines the waveforms of the first drive signal Com-A and the second drive signal Com-B.

[0028] The control circuit 21 executes a program stored in the memory circuit 22 to control the operation of each part of the liquid ejection device 100. Here, by executing the program, the control circuit 21 generates control signals Sk1 and Sk2, a print data signal SI, a waveform designation signal dCom, a latch signal LAT, a change signal CNG, and a clock signal CLK as signals for controlling the operation of each part of the liquid ejection device 100.

[0029] The control signal Sk1 is a signal for controlling the driving of the transport mechanism 30. The control signal Sk2 is a signal for controlling the driving of the movement mechanism 40. The print data signal SI is a digital signal for specifying the operating state of the piezoelectric element 51f. The latch signal LAT and the change signal CNG are used in conjunction with the print data signal SI and are timing signals that determine the timing of ink ejection from each nozzle of the head chip 51. These timing signals are generated, for example, based on the output of an encoder that detects the position of the carriage 41 mentioned above.

[0030] 1-3. Overall configuration of liquid ejection head Fig. 3 is an exploded perspective view of head chip 51. Fig. 4 is a cross-sectional view taken along line AA in Fig. 3. As shown in Fig. 3 and Fig. 4, head chip 51 has a flow path substrate 51a, a pressure chamber substrate 51b, a nozzle plate 51c, a vibration absorber 51d, a diaphragm 51e, a plurality of piezoelectric elements 51f, a cover 51g, a case 51h, and a wiring substrate 51i.

[0031] Here, a pressure chamber substrate 51b, a vibration plate 51e, a plurality of piezoelectric elements 51f, a case 51h, and a cover 51g are disposed in an area positioned further in the Z1 direction than the flow path substrate 51a. On the other hand, a nozzle plate 51c and a vibration absorber 51d are disposed in an area positioned further in the Z2 direction than the flow path substrate 51a. Each element of the liquid ejection head 50 is generally a plate-like member that is elongated in the direction along the Y axis, and is joined to one another by, for example, an adhesive.

[0032] As shown in FIG. 3, the nozzle plate 51c is a plate-shaped member provided with a plurality of nozzles N arranged in a direction along the Y axis. Each nozzle N is a through-hole that allows ink to pass through. The nozzle plate 51c is manufactured by processing a silicon single crystal substrate using semiconductor manufacturing techniques such as dry etching or wet etching. However, other known methods and materials may also be used as appropriate to manufacture the nozzle plate 51c.

[0033] The flow path substrate 51a is a plate-like member for forming ink flow paths. As shown in FIGS. 2 and 3, the flow path substrate 51a is provided with an opening R1, multiple supply flow paths Ra, and multiple communication flow paths Na. The opening R1 is an elongated through-hole extending in the Y-axis direction in a plan view along the Z-axis so as to connect to the multiple nozzles N. On the other hand, the supply flow paths Ra and the communication flow paths Na are through-holes individually provided for each nozzle N. Each of the multiple supply flow paths Ra communicates with the opening R1. Like the nozzle plate 51c described above, the flow path substrate 51a is manufactured by processing a silicon single crystal substrate using semiconductor manufacturing technology, for example. However, other known methods and materials may also be used to manufacture the flow path substrate 51a. Note that a portion of the supply flow path Ra may be formed in the pressure chamber substrate 51b.

[0034] The pressure chamber substrate 51b is a plate-like member in which multiple pressure chambers C corresponding to the multiple nozzles N are formed. The pressure chambers C are spaces called cavities located between the flow path substrate 51a and the vibration plate 51e, and are used to apply pressure to the ink filling the pressure chambers C. The multiple pressure chambers C are arranged in a direction along the Y axis. Each pressure chamber C is formed by a hole that opens on both sides of the pressure chamber substrate 51b and is elongated in a direction along the X axis. The X2-direction end of each pressure chamber C communicates with a corresponding supply flow path Ra. The cross-sectional area of ​​the supply flow path Ra is narrower than that of the pressure chambers C, and this portion functions as a flow path resistance, thereby suppressing backflow when pressure is applied to the ink. Meanwhile, the X1-direction end of each pressure chamber C communicates with a corresponding communication flow path Na. Like the nozzle plate 51c described above, the pressure chamber substrate 51b is manufactured by processing a silicon single crystal substrate using, for example, semiconductor manufacturing technology. However, other known methods and materials may be used appropriately to manufacture each of the pressure chamber substrates 51b.

[0035] A diaphragm 51e is disposed on the surface of the pressure chamber substrate 51b facing the Z1 direction. The diaphragm 51e is a plate-like member that is elastically deformable. In the example shown in FIG. 4, the diaphragm 51e has a first layer 51e1 that is an elastic film and a second layer 51e2 that is an insulating film, which are laminated in this order in the Z1 direction. Details of the diaphragm 51e will be described later with reference to FIG. 6.

[0036] A plurality of piezoelectric elements 51f corresponding to different nozzles N or pressure chambers C are arranged on the surface of the vibration plate 51e facing the Z1 direction. Each piezoelectric element 51f is a passive element that deforms in response to the supply of a first drive signal Com-A and a second drive signal Com-B, and has an elongated shape extending in the direction along the X axis. The plurality of piezoelectric elements 51f are arranged in the direction along the Y axis so as to correspond to the plurality of pressure chambers C. When the vibration plate 51e vibrates in conjunction with the deformation of the piezoelectric elements 51f, the pressure in the pressure chambers C fluctuates, causing ink to be ejected from the nozzles N. Details of the piezoelectric elements 51f will be described later with reference to FIG. 6.

[0037] The case 51h is a case for storing ink to be supplied to the multiple pressure chambers C, and is bonded to the surface of the flow path substrate 51a facing the Z1 direction with an adhesive or the like. The case 51h is made of, for example, a resin material and manufactured by injection molding. The case 51h is provided with a storage section R2 and an inlet IH. The storage section R2 is a recessed portion whose outer shape corresponds to the opening R1 of the flow path substrate 51a. The inlet IH is a through-hole that communicates with the storage section R2. The space formed by the opening R1 and the storage section R2 functions as a liquid storage chamber R, which is a reservoir that stores ink. Ink is supplied to the liquid storage chamber R from the liquid container 10 via the inlet IH.

[0038] The vibration absorber 51d is an element for absorbing pressure fluctuations within the liquid storage chamber R. The vibration absorber 51d is, for example, a compliance substrate that is a flexible sheet member that can be elastically deformed. Here, the vibration absorber 51d is arranged on the surface of the flow path substrate 51a facing the Z2 direction so as to close the opening R1 and the multiple supply flow paths Ra of the flow path substrate 51a and form the bottom surface of the liquid storage chamber R.

[0039] The cover 51g is a structure that protects the multiple piezoelectric elements 51f and reinforces the mechanical strength of the pressure chamber substrate 51b and the vibration plate 51e. The cover 51g is bonded to the surface of the vibration plate 51e with, for example, an adhesive. The cover 51g is provided with recesses that accommodate the multiple piezoelectric elements 51f.

[0040] A wiring board 51i is bonded to the surface of the pressure chamber substrate 51b or the vibration plate 51e facing the Z1 direction. The wiring board 51i is a mounting component on which a plurality of wires are formed for electrically connecting the control unit 20 and the liquid ejection head 50. The wiring board 51i is a flexible wiring board such as an FPC (Flexible Printed Circuit) or an FFC (Flexible Flat Cable). A switching circuit 52 is mounted on the wiring board 51i.

[0041] 1-4. Details of the diaphragm and piezoelectric element Fig. 5 is a plan view of the head chip 51. Fig. 6 is a cross-sectional view taken along line BB in Fig. 5. In Fig. 5, the planar shape of the pressure chamber C is indicated by a two-dot chain line. A wall-like partition 51b1 extending along the X direction is provided between two adjacent pressure chambers C of the pressure chamber substrate 51b. The partition 51b1 divides the pressure chambers C.

[0042] In the example shown in FIG. 5, the pressure chamber C has a parallelogram shape in a plan view. The pressure chamber C having such a shape in a plan view is formed, for example, by anisotropically etching a silicon single crystal substrate having a (110) surface orientation. An etchant used in the anisotropic etching is, for example, an aqueous potassium hydroxide solution (KOH). In the anisotropic etching, the first layer 51e1 of the diaphragm 51e is used as an etching stop layer. The shape of the pressure chamber C in a plan view is not limited to the example shown in FIG. 5 and may be any shape.

[0043] As shown in Fig. 6, the vibration plate 51e has a first surface F1 and a second surface F2 facing in the opposite direction to the first surface F1. In the example shown in Fig. 6, the thickness direction of the vibration plate 51e is along the Z axis. Therefore, the first surface F1 is the surface of the vibration plate 51e facing in the Z2 direction, and the second surface F2 is the surface of the vibration plate 51e facing in the Z1 direction. A piezoelectric element 51f is disposed on the second surface F2. A pressure chamber substrate 51b is disposed on the first surface F1.

[0044] The diaphragm 51e has a first layer 51e1 and a second layer 51e2, which are stacked in this order in the Z1 direction. The first layer 51e1 is an elastic film made of, for example, silicon oxide (SiO2). The elastic film is formed, for example, by thermally oxidizing one surface of a silicon single crystal substrate. The second layer 51e2 is an insulating film made of, for example, zirconium oxide (ZrO2). The insulating film is formed, for example, by forming a zirconium layer by sputtering and then thermally oxidizing the layer.

[0045] The first layer 51e1 is not limited to silicon oxide and may be made of other elastic materials such as silicon alone. The material of the second layer 51e2 is not limited to zirconium oxide and may be other insulating materials such as silicon nitride. Another layer such as a metal oxide may be interposed between the first layer 51e1 and the second layer 51e2. In other words, the first layer 51e1 or the second layer 51e2 may be made of multiple layers, which may be the same or different from each other. A part or all of the diaphragm 51e may be made integral with the pressure chamber substrate 51b using the same material. The diaphragm 51e may also be made of a layer of a single material.

[0046] As shown in Fig. 5, the piezoelectric element 51f overlaps the pressure chamber C in a plan view. As shown in Fig. 6, the piezoelectric element 51f has a first electrode layer 51f1, a piezoelectric layer 51f2, and a second electrode layer 51f3, which is an example of a "common electrode," which are stacked in this order in the Z1 direction. Therefore, the first electrode layer 51f1 is interposed between the vibration plate 51e and the second electrode layer 51f3.

[0047] Other layers, such as layers for improving adhesion, may be interposed between the layers of the piezoelectric elements 51f or between the piezoelectric elements 51f and the diaphragm 51e. A seed layer may be provided between the first electrode layer 51f1 and the piezoelectric layer 51f2. The seed layer functions to improve the orientation of the piezoelectric layer 51f2 when the piezoelectric layer 51f2 is formed. The seed layer may be made of, for example, titanium (Ti) or a complex oxide having a perovskite structure, such as Pb(Fe,Ti)O3. When the seed layer is made of titanium, islands of Ti serve as crystal nuclei during the formation of the piezoelectric layer 51f2, improving the orientation of the piezoelectric layer 51f2. In this case, the seed layer is formed to a thickness of approximately 3 nm to 20 nm using a known film formation technique, such as sputtering, and a known processing technique using photolithography and etching. Furthermore, when the seed layer is made of the complex oxide, the crystal structure of the seed layer affects the piezoelectric layer 51f2 during formation, improving the orientation of the piezoelectric layer 51f2. In this case, the seed layer is formed by, for example, forming a precursor layer of the complex oxide by a sol-gel method or a metal organic decomposition (MOD) method, and then firing the precursor layer to crystallize it.

[0048] The first electrode layer 51f1 has, for each piezoelectric element 51f, an individual electrode 51f11 which is an example of a "first individual electrode," an individual electrode 51f12 which is an example of a "second individual electrode," and an individual electrode 51f13 which is an example of a "third individual electrode." Each of the individual electrodes 51f11, 51f12, and 51f13 extends in the direction along the X-axis. The individual electrodes 51f11, 51f12, and 51f13 are arranged in the direction along the Y-axis at intervals from one another.

[0049] In this embodiment, the positions in the X1 direction of the end of the individual electrode 51f11 in the X1 direction and the end of the individual electrode 51f12 in the X1 direction are different from each other. Similarly, the positions in the X2 direction of the end of the individual electrode 51f11 in the X2 direction and the end of the individual electrode 51f12 in the X2 direction are different from each other. By shifting the ends of the individual electrodes 51f11 and 51f12 from each other in this manner, even if the second electrode layer 51f3 is provided over an area including the active portions P1 and P2 described below in a plan view, it is possible to provide the first region RA1, second region RA2, and third region RA3 described below.

[0050] Here, the individual electrode 51f11 is disposed at the center of the pressure chamber C in the width direction in a plan view, and overlaps with the center of the pressure chamber C. In other words, the individual electrode 51f11 overlaps with the center of the pressure chamber C in the direction along the Y axis when viewed along the Z axis. A first drive signal Com-A is supplied to the individual electrode 51f11 via an individual wiring 51j, which is an example of a "first individual wiring." Meanwhile, the individual electrodes 51f12 and 51f13 are each disposed at an end of the pressure chamber C in the width direction in a plan view. In other words, the individual electrode 51f12 is disposed in the Y2 direction when viewed from the individual electrode 51f11, and the individual electrode 51f13 is disposed in the Y1 direction when viewed from the individual electrode 51f11. Furthermore, the individual electrodes 51f12 and 51f13 overlap with the pressure chamber C at a position closer to the outer edge BD of the pressure chamber C in the width direction than the individual electrode 51f11. A second drive signal Com-B is supplied to each of the individual electrodes 51f12 and 51f13 via an individual wiring 51k, which is an example of a "second individual wiring."

[0051] 5, the individual wiring 51j and the individual wiring 51k are drawn out in opposite directions from the piezoelectric element 51f. Here, the individual wiring 51j is connected to the individual electrode 51f11 at a position offset from the center of the individual electrode 51f11 in the direction along the X-axis. More specifically, the individual wiring 51j is connected to an end of the individual electrode 51f11 in the X2 direction and has a portion extending from that end in the X2 direction. Meanwhile, the individual wiring 51k is connected to the individual electrode 51f12 at a position offset from the center of the individual electrode 51f12 in the direction along the X-axis in the opposite direction to the individual wiring 51j. More specifically, the individual wiring 51k is connected to the ends of the individual electrodes 51f12 and 51f13 in the X1 direction and has a portion extending from that end in the X1 direction. Furthermore, individual wiring 51k extending from individual electrode 51f12 and individual wiring 51k extending from individual electrode 51f13 are connected to each other within head chip 51. This simplifies the routing of individual wiring 51k within head chip 51 and reduces the number of wires on wiring board 51i. Note that individual wiring 51k extending from individual electrode 51f12 and individual wiring 51k extending from individual electrode 51f13 may be connected to wiring board 51i individually without being connected to each other.

[0052] The individual wirings 51j and 51k are provided as a layer separate from the first electrode layer 51f1. Here, the individual wirings 51j and 51k are layers formed after the formation of the first electrode layer 51f1. The individual wirings 51j and 51k may be layers formed simultaneously with the formation of the first electrode layer 51f1, or may be provided in the same layer as the first electrode layer 51f1.

[0053] The first electrode layer 51f1 has, for example, a first layer made of titanium (Ti), a second layer made of platinum (Pt), and a third layer made of iridium (Ir), which are stacked in this order in the Z1 direction. The first electrode layer 51f1 is formed by, for example, a known film formation technique such as sputtering, and a known processing technique using photolithography, etching, etc.

[0054] Here, the first layer of the first electrode layer 51f1 functions as an adhesion layer that improves adhesion of the first electrode layer 51f1 to the diaphragm 51e. The thickness of the first layer is not particularly limited, but is, for example, about 3 nm to 50 nm. The material of the first layer is not limited to titanium; for example, chromium may be used instead of titanium.

[0055] Furthermore, the platinum constituting the second layer and the iridium constituting the third layer of the first electrode layer 51f1 are both electrode materials with excellent conductivity and similar chemical properties. This allows the first electrode layer 51f1 to have excellent electrode characteristics. The thickness of the second layer is not particularly limited, but is, for example, approximately 50 nm to 200 nm. The thickness of the third layer is not particularly limited, but is, for example, approximately 4 nm to 20 nm.

[0056] The configuration of the first electrode layer 51f1 is not limited to the above example. For example, either the second or third layer may be omitted, or a layer made of iridium may be provided between the first and second layers. Furthermore, instead of or in addition to the second and third layers, a layer made of an electrode material other than iridium and platinum may be used. Examples of such electrode materials include metal materials such as aluminum (Al), nickel (Ni), gold (Au), and copper (Cu). One of these materials may be used alone, or two or more may be combined in the form of a laminate or alloy.

[0057] The individual wirings 51j and 51k are made of a metal material such as platinum (Pt), aluminum (Al), nickel (Ni), gold (Au), or copper (Cu). The individual wirings 51j and 51k are formed by known film formation techniques such as sputtering, and known processing techniques using photolithography and etching. The individual wirings 51j and 51k may be made of one of the above-mentioned metal materials alone, or may be made of two or more of them combined in the form of a laminate or alloy. The individual wirings 51j and 51k may be formed together with the second electrode layer 51f3 described below.

[0058] The piezoelectric layer 51f2 is disposed between the first electrode layer 51f1 and the second electrode layer 51f3. The piezoelectric layer 51f2 has a strip shape extending in the direction along the Y axis so as to be continuous across the plurality of piezoelectric elements 51f. Note that the piezoelectric layer 51f2 may be provided individually for each piezoelectric element 51f or for each active portion P1, P2, and P3.

[0059] The piezoelectric layer 51f2 is made of a piezoelectric material having a perovskite crystal structure represented by the general composition formula ABO3. Examples of such piezoelectric materials include lead titanate (PbTiO3), lead zirconate titanate (Pb(Zr,Ti)O3), lead zirconate (PbZrO3), lead lanthanum titanate ((Pb,La),TiO3), lead lanthanum zirconate titanate ((Pb,La)(Zr,Ti)O3), lead zirconium niobate titanate (Pb(Zr,Ti,Nb)O3), and lead magnesium zirconium niobate titanate (Pb(Zr,Ti)(Mg,Nb)O3). Among these, lead zirconate titanate is preferably used as the material for the piezoelectric layer 51f2. The piezoelectric layer 51f2 may contain small amounts of other elements, such as impurities. The piezoelectric material forming the piezoelectric layer 51f2 may be a lead-free material such as barium titanate.

[0060] The piezoelectric layer 51f2 is formed by forming a piezoelectric precursor layer by a liquid phase method such as a sol-gel method or a metal organic decomposition (MOD) method, and then baking and crystallizing the precursor layer. Here, the piezoelectric layer 51f2 may be composed of a single layer, but if it is composed of multiple layers, there is an advantage that the characteristics of the piezoelectric layer 51f2 can be easily improved even if the thickness of the piezoelectric layer 51f2 is increased.

[0061] The second electrode layer 51f3 is a strip-shaped common electrode that extends continuously in the direction along the Y-axis across the plurality of piezoelectric elements 51f. An offset potential VBS is supplied to the second electrode layer 51f3 as a predetermined reference voltage.

[0062] The second electrode layer 51f3 has, for example, a layer made of iridium (Ir) and a layer made of titanium (Ti), which are stacked in this order in the Z1 direction. The second electrode layer 51f3 is formed by, for example, a known film formation technique such as sputtering, and a known processing technique using photolithography, etching, etc.

[0063] The constituent materials of the second electrode layer 51f3 are not limited to iridium and titanium, and may be, for example, metal materials such as platinum (Pt), aluminum (Al), nickel (Ni), gold (Au), or copper (Cu). The second electrode layer 51f3 may be composed of one of these metal materials alone, or may be composed of two or more of them combined in the form of a laminate or alloy. The second electrode layer 51f3 may also be composed of a single layer.

[0064] The piezoelectric element 51f has active portions P1, P2, and P3. As shown in FIG. 6, the active portion P1 is a portion of the piezoelectric element 51f where the individual electrode 51f11, the piezoelectric layer 51f2, and the second electrode layer 51f3 all overlap when viewed in the thickness direction of the diaphragm 51e. The active portion P2 is a portion of the piezoelectric element 51f where the individual electrode 51f12, the piezoelectric layer 51f2, and the second electrode layer 51f3 all overlap when viewed in the thickness direction of the diaphragm 51e. The active portion P3 is a portion of the piezoelectric element 51f where the individual electrode 51f13, the piezoelectric layer 51f2, and the second electrode layer 51f3 all overlap when viewed in the thickness direction of the diaphragm 51e.

[0065] The active portion P1 is disposed between the active portions P2 and P3 in the direction along the Y axis. Here, the active portion P1 is disposed closer to the center of the pressure chamber C in the Y1 or Y2 direction than the active portions P2 and P3. Furthermore, the active portions P2 and P3 are disposed closer to the ends of the pressure chamber C in the Y1 or Y2 direction than the active portion P1. In the example shown in FIG. 6, the active portion P2, active portion P1, and active portion P3 are lined up in this order in the Y1 direction. Furthermore, each of the active portions P1, P2, and P3 extends in the direction along the X axis.

[0066] Here, at least a portion of each of the active portions P1 and P2 overlaps with the pressure chamber C when viewed in the direction along the Z axis. More specifically, the active portion P1 overlaps with the center of the pressure chamber C when viewed in the thickness direction of the diaphragm 51e, but does not overlap with the outer edge BD of the pressure chamber C. On the other hand, each of the active portions P2 and P3 overlaps with the pressure chamber C at a position closer to the outer edge BD of the pressure chamber C than the active portion P1 when viewed in the thickness direction of the diaphragm 51e. In the example shown in FIG. 6, each of the active portions P2 and P3 is disposed across the pressure chamber C and the partition wall 51b1 when viewed in the thickness direction of the diaphragm 51e, and overlaps with the outer edge BD.

[0067] The width W1 of the active portion P1 along the Y axis is smaller than the width of the pressure chamber C along the Y axis, preferably smaller than the width of the pressure chamber C along the Y axis and at least half the width of the pressure chamber C along the Y axis. Furthermore, the width W2 of the active portion P2 along the Y axis is smaller than the width of the pressure chamber C along the Y axis, preferably not more than half the width of the pressure chamber C along the Y axis. Similarly, the width W3 of the active portion P3 along the Y axis is smaller than the width of the pressure chamber C along the Y axis, preferably not more than half the width of the pressure chamber C along the Y axis. Here, the widths W2 and W3 may be equal to or different from each other.

[0068] In this embodiment, the width of each of the active portions P1, P2, and P3 is constant over the entire area in the direction along the X-axis. However, the width of each of the active portions P1, P2, and P3 does not have to be constant, and for example, each of the active portions P1, P2, and P3 may have portions with different widths, as in the second embodiment described below.

[0069] 5, in order to reduce stresses locally generated in the diaphragm 51e near the ends of the active parts P1, P2, and P3 in the X1 direction, the position of the end of the active part P1 in the X1 direction is offset from the position of the end of the active parts P2 and P3 in the X1 direction in the direction along the X axis. Similarly, in order to reduce stresses locally generated in the diaphragm 51e near the ends of the active parts P1, P2, and P3 in the X2 direction, the position of the end of the active part P1 in the X2 direction is offset from the position of the end of the active parts P2 and P3 in the X2 direction in the direction along the X axis.

[0070] Such a piezoelectric element 51f has a first region RA1, a second region RA2, and a third region RA3. In the first region RA1, all of the active portions P1, P2, and P3 are arranged along the X-axis. In contrast, in each of the second region RA2 and the third region RA3, one of the active portion P1 and the active portions P2 and P3 is arranged along the X1 direction or the X2 direction, and the other is not arranged along the X-axis. Details of these regions will be described later with reference to FIGS. 12 to 14.

[0071] 1-5. Switching circuit configuration 7 is a diagram for explaining the switching circuit 52. The switching circuit 52 will be explained below with reference to FIG.

[0072] 7, the switching circuit 52 is connected to a line LHa and a line LHb. The line LHa is a signal line that transmits a first drive signal Com-A. The line LHb is a signal line that transmits a second drive signal Com-B. The second electrode layer 51f3 of the piezoelectric element 51f is connected to a line LHd. The line LHd is a power supply line that supplies an offset potential VBS.

[0073] The switching circuit 52 has a plurality of switches SWa and a plurality of switches SWb that correspond one-to-one to the plurality of piezoelectric elements 51f, and a connection state designation circuit 52a that designates the connection state of these switches.

[0074] The switch SWa switches between conduction (ON) and non-conduction (OFF) between the wiring LHa for transmitting the first drive signal Com-A and the individual electrode 51f11 of the piezoelectric element 51f. The switch SWb switches between conduction (ON) and non-conduction (OFF) between the wiring LHa for transmitting the second drive signal Com-B and the individual electrodes 51f12 and 51f13 of the piezoelectric element 51f. Each of these switches is, for example, a transmission gate.

[0075] The connection state designation circuit 52a generates a connection state designation signal SLa that designates the on / off states of the multiple switches SWa and multiple switches SWb based on the clock signal CLK, print data signal SI, latch signal LAT, and change signal CNG supplied from the control circuit 21.

[0076] For example, although not shown, the connection state designation circuit 52a includes multiple transfer circuits, multiple latch circuits, and multiple decoders, each corresponding to one of the piezoelectric elements 51f. Of these, the transfer circuit receives a print data signal SI. The print data signal SI includes an individual designation signal for each piezoelectric element 51f. The individual designation signals are serially supplied and transferred sequentially to the multiple transfer circuits in synchronization with a clock signal CLK. The latch circuit latches the individual designation signal supplied to the transfer circuit based on a latch signal LAT. The decoder generates a connection state designation signal SLa based on the individual designation signal, the latch signal LAT, and the change signal CNG.

[0077] The switches SWa and SWb are switched on and off according to the connection state designation signal SLa generated as described above. For example, the switches SWa and SWb are turned on when the connection state designation signal SLa is at a high level, and turned off when the connection state designation signal SLa is at a low level. As described above, the switching circuit 52 supplies part or all of the waveform included in the first drive signal Com-A as the supply signal Vin-A, and supplies part or all of the waveform included in the second drive signal Com-B as the supply signal Vin-B, to one or more piezoelectric elements 51f selected from the plurality of piezoelectric elements 51f.

[0078] 1-6. First drive signal and second drive signal Fig. 8 is a diagram for explaining the first drive signal Com-A and the second drive signal Com-B in the first embodiment. The vertical axis "voltage" in the upper part of Fig. 8 is the potential difference between the first drive signal Com-A and the offset potential VBS, and the vertical axis "voltage" in the lower part of Fig. 8 is the potential difference between the second drive signal Com-B and the offset potential VBS. Note that the vertical axis "voltage" in the upper part of Fig. 8 may be the potential of the first drive signal Com-A, and the vertical axis "voltage" in the lower part of Fig. 8 may be the potential of the second drive signal Com-B.

[0079] 8, the first drive signal Com-A and the second drive signal Com-B each have a waveform that changes every unit period Tu of a predetermined cycle. The unit period Tu is determined by the latch signal LAT and the like, and corresponds to the printing cycle in which dots are formed on the medium M using ink from the nozzles N.

[0080] 8, the first drive signal Com-A has a waveform that, with the intermediate potential Vca as a reference potential, changes from the intermediate potential Vca via a potential VHa and back to the intermediate potential Vca within a unit period Tu. Here, the intermediate potential Vca is an example of a "first potential" and a "fifth potential," and is, for example, a potential equal to or lower than the offset potential VBS. The potential VHa is an example of a "second potential," and is a potential higher than the offset potential VBS and higher than the intermediate potential Vca.

[0081] Here, the potential of the first drive signal Com-A is maintained at the intermediate potential Vca for a period P1a, then rises from the intermediate potential Vca to a potential VHa for a period P2a, is maintained at the potential VHa for a period P3a, then falls from the potential VHa to the intermediate potential Vca for a period P4a, and is maintained at the intermediate potential Vca for a period P5a. The period P2a is an example of a "first period." The period P3a is an example of a "first hold period." The period P4a is an example of a "third period." The periods P1a, P2a, P3a, P4a, and P5a are included, in this order, between the start and end points of the unit period Tu.

[0082] The waveform portion of the first drive signal Com-A during period P2a is a contraction element ESa that contracts the volume of the pressure chamber C. The contraction element ESa is an example of a "first contraction element." The waveform portion of the first drive signal Com-A during period P3a is a hold element ERa, which is an example of a "first hold element." The waveform portion of the first drive signal Com-A during period P4a is an expansion element EEa that expands the volume of the pressure chamber C.

[0083] On the other hand, the second drive signal Com-B has a waveform that, with the intermediate potential Vcb as a reference potential, changes from the intermediate potential Vcb via the potential VHb and back to the intermediate potential Vcb within the unit period Tu. Here, the intermediate potential Vcb is an example of the "third potential" and "sixth potential," and is, for example, a potential equal to or lower than the offset potential VBS. The potential VHb is an example of the "fourth potential," and is a potential higher than the offset potential VBS and also higher than the intermediate potential Vcb.

[0084] Here, the potential of the second drive signal Com-B is maintained at the intermediate potential Vcb for a period P1b, then rises from the intermediate potential Vcb to a potential VHb for a period P2b, is maintained at the potential VHb for a period P3b, then falls from the potential VHb to the intermediate potential Vcb for a period P4b, and is maintained at the intermediate potential Vcb for a period P5b. The period P4b is an example of a "second period." The period P3b is an example of a "second hold period." The period P2b is an example of a "fourth period." The periods P1b, P2b, P3b, P4b, and P5b are included, in this order, between the start and end points of the unit period Tu.

[0085] The waveform portion of the second drive signal Com-B during period P2b is an expansion element EEb that expands the volume of the pressure chamber C. The waveform portion of the second drive signal Com-B during period P3b is a hold element ERb, which is an example of a "second hold element." The waveform portion of the second drive signal Com-B during period P4b is a contraction element ESb that contracts the volume of the pressure chamber C. The contraction element ESb is an example of a "second contraction element."

[0086] In this embodiment, the first drive signal Com-A and the second drive signal Com-B have substantially identical waveforms. However, the first drive signal Com-A and the second drive signal Com-B are supplied with waveforms that are out of phase with each other. Note that "substantially identical waveforms" means that the patterns match when waveforms due to electrical noise and errors are removed.

[0087] That is, the length of period P1a of the first drive signal Com-A is longer than the length of period P1b of the second drive signal Com-B. The length of period P2a of the first drive signal Com-A and the length of period P2b of the second drive signal Com-B are equal. The length of period P3a of the first drive signal Com-A and the length of period P3b of the second drive signal Com-B are equal. The length of period P4a of the first drive signal Com-A and the length of period P4b of the second drive signal Com-B are equal. The length of period P5a of the first drive signal Com-A is shorter than the length of period P5b of the second drive signal Com-B.

[0088] The waveforms of the first drive signal Com-A and the second drive signal Com-B may be different from each other. However, if the waveforms of the first drive signal Com-A and the second drive signal Com-B are substantially the same, the drive signal generation circuit 24 may be able to generate a single waveform and supply it with a phase shift. This has the advantage of simplifying the configuration of the drive signal generation circuit 24 compared to when the waveforms of the first drive signal Com-A and the second drive signal Com-B are different from each other.

[0089] The start timing of the period P3a of the first drive signal Com-A is after the end timing of the period P3b of the second drive signal Com-B.

[0090] Here, at least a portion of the period P2a of the first drive signal Com-A and at least a portion of the period P4b of the second drive signal Com-B overlap each other in time during the period PS.

[0091] 8, within the unit period Tu, the start timing of the period P2a is later than the start timing of the period P4b, and accordingly, within the unit period Tu, the end timing of the period P2a is later than the end timing of the period P4b.

[0092] 1-7. Shrinkage process Fig. 9 is a diagram for explaining the contraction process SS in the first embodiment. In Fig. 9, the first drive signal Com-A is indicated by a solid line, and the second drive signal Com-B is indicated by a dashed line. In the example shown in Fig. 9, the potentials VHa and VHb are equal to each other, and the intermediate potentials Vca and Vcb are equal to each other.

[0093] The potentials VHa and VHb may be different from each other, and the intermediate potentials Vca and Vcb may be different from each other. However, when the potentials VHa and VHb are equal to each other and the intermediate potentials Vca and Vcb are equal to each other, there is an advantage in that the configuration of the drive signal generation circuit 24 can be simplified compared to when they are not.

[0094] As described above, after the supply of the hold element ERb of the second drive signal Com-B to the active units P2 and P3 is completed, the supply of the hold element ERa of the first drive signal Com-A to the active unit P1 begins after the period PS. Here, the period PS is a period in which the period for driving the active unit P1 and the period for driving the active unit P2 at least partially overlap each other. During the period PS, the contraction process SS is executed.

[0095] FIG. 10 is a schematic diagram illustrating the deformation of the diaphragm 51e due to the first drive signal Com-A. FIG. 11 is a schematic diagram illustrating the deformation of the diaphragm due to the second drive signal Com-B. In these figures, for the sake of convenience, the piezoelectric element 51f is omitted from the illustration, and the diaphragm 51e is shown schematically. In addition, in FIGS. 10 and 11, the diaphragm 51e in its natural state, which is its reference state, is indicated by a two-dot chain line. Note that the "natural state of the diaphragm 51e" refers to the state of the diaphragm 51e when no voltage is applied to the piezoelectric element 51f.

[0096] When a voltage is applied in the direction along the Z axis, each of the active parts P1, P2, and P3 expands along the Z axis and attempts to contract in a direction perpendicular to the Z axis. At this time, because the surfaces of the active parts P1, P2, and P3 facing the Z2 direction are fixed to the diaphragm 51e, the amount of contraction of the surfaces of the active parts P1, P2, and P3 facing the Z2 direction is smaller than the amount of contraction of the surfaces of the active parts P1, P2, and P3 facing the Z1 direction. As a result, the active parts P1, P2, and P3 deform so as to warp in the direction along the Z axis, and the diaphragm 51e also deforms accordingly.

[0097] Here, of the two ends of each of the active portions P2 and P3 along the Y axis, the end closest to the partition wall 51b1 of the pressure chamber C is restricted in displacement by the partition wall 51b1, while the end farther from the partition wall 51b1 of the pressure chamber C is less restricted in displacement. Therefore, when the active portions P2 and P3 attempt to contract along the Y axis, the farther end displaces in the Z1 direction. As a result, the diaphragm 51e deforms so that the first surface F1 becomes concave. Therefore, when the holding element ERb of the second drive signal Com-B is supplied to the active portions P2 and P3, the diaphragm 51e deforms so that the first surface F1 becomes concave, as shown in FIG. 10. This causes the volume of the pressure chamber C to expand.

[0098] On the other hand, both ends of the active portion P1 in the direction along the Y axis are located relatively far from the partition wall 51b1 of the pressure chamber C, and displacement is less likely to be restricted by the partition wall 51b1. Therefore, when the active portion P1 attempts to contract in the direction along the Y axis, the diaphragm 51e deforms so that the first surface F1 becomes convex. Therefore, when the holding element ERa of the first drive signal Com-A is supplied to the active portion P1, the diaphragm 51e deforms so that the first surface F1 becomes convex, as shown in FIG. 11. This causes the volume of the pressure chamber C to contract.

[0099] Here, during the period in which the contraction element ESb of the second drive signal Com-B is supplied, the active units P2 and P3 attempt to return the diaphragm 51e from the state shown by the solid line to the state shown by the two-dot chain line in Fig. 10. Also, during the period in which the active unit P1 receives the contraction element ESa of the first drive signal Com-A, the active unit P1 attempts to deform the diaphragm 51e from the state shown by the two-dot chain line to the state shown by the solid line in Fig. 11.

[0100] In the contraction process SS, when the diaphragm 51e is deformed from the state indicated by the two-dot chain line in FIG. 11 to the state indicated by the solid line, the force that attempts to return the diaphragm 51e from the state indicated by the solid line in FIG. 10 to the state indicated by the two-dot chain line can be utilized. That is, in the contraction process SS, when the active part P1 deforms the diaphragm 51e from the reference state to the state that contracts the volume of the pressure chamber C, the forces that the active parts P2 and P3 attempt to return the diaphragm 51e from the state in which the volume of the pressure chamber C is expanded to the reference state can be utilized. Therefore, the amount of deformation of the diaphragm 51e can be made larger compared to a configuration in which only the active part P1 is driven by the first drive signal Com-A. As a result, ink can be ejected efficiently from the nozzle N.

[0101] In contrast, if the start timing of the supply of the contraction element ESa of the first drive signal Com-A to the active portion P1 coincides with or after the end timing of the supply to the active portions P2 and P3, when the diaphragm 51e is deformed from the state shown by the two-dot chain line in FIG. 11 to the state shown by the solid line, the force that attempts to return the diaphragm 51e from the state shown by the solid line in FIG. 10 to the state shown by the two-dot chain line cannot be fully utilized, and the above-mentioned effect tends to be reduced. Note that the start timing of the supply of the contraction element ESa of the first drive signal Com-A to the active portion P1 may coincide with or after the end timing of the supply to the active portions P2 and P3. However, from the viewpoint of efficiently ejecting ink from the nozzle N, it is preferable that the length of time between the start timing and the end timing be as short as possible.

[0102] 1-8. Area 1, Area 2 and Area 3 FIG. 12 is a diagram illustrating the first region RA1, the second region RA2, and the third region RA3 of the piezoelectric element 51f in the first embodiment. FIG. 13 is a cross-sectional view of the second region RA2. FIG. 14 is a cross-sectional view of the third region RA3. FIG. 15 is a diagram illustrating, as a comparative example, a configuration in which the longitudinal ends of the first region RA1, the second region RA2, and the third region RA3 are aligned. The upper parts of FIGS. 12 and 15 each show a schematic planar arrangement of the first region RA1, the second region RA2, and the third region RA3. The lower parts of FIGS. 12 and 15 each show a graph illustrating the relationship between the horizontal axis representing position along the X-axis and the vertical axis representing strain generated in the diaphragm 51e. Here, the strain on the vertical axis is the sum of the strains generated in the diaphragm 51e due to the driving of the active portion P1 and the active portions P2 and P3.

[0103] 12, the first region RA1 is a region in which both the active portion P1 and the active portion P2 are provided along the X-axis. In this embodiment, in addition to the active portion P1 and the active portion P2, the first region RA1 also has an active portion P3 provided along the X1 direction or the X2 direction. Here, the first region RA1 is a region between the second region RA2 and the third region RA3.

[0104] The second region RA2 is a region in which one of the active portion P1 and the active portion P2 is provided along the X1 direction or the X2 direction, and the other is not provided along the X axis. In this embodiment, as shown in Fig. 13, the second region RA2 is a region in which the active portion P2 is provided along the X axis, and the active portion P1 is not provided along the X axis. In addition to the active portion P2, the second region RA2 is also provided with the active portion P2 along the X axis.

[0105] Here, of both ends of the second region RA2 in the direction along the X axis, the end farther from the first region RA1, i.e., the end of the second region RA2 in the X1 direction, overlaps with the pressure chamber C when viewed in the Z1 or Z2 direction.

[0106] The third region RA3 is a region where one of the active portion P1 and the active portion P2 is provided along the X-axis, and the other is not provided along the X-axis. In this embodiment, as shown in Fig. 14, the third region RA3 is a region where the active portion P1 is provided along the X-axis, and the active portion P2 is not provided along the X-axis. Furthermore, the active portion P3 is also not provided along the X-axis in the third region RA3.

[0107] Here, of both ends of the third region RA3 in the direction along the X axis, the end farther from the first region RA1, i.e., the end of the third region RA3 in the X2 direction, overlaps with the pressure chamber C when viewed in the Z1 or Z2 direction.

[0108] As described above, the first region RA1 is provided with all of the active portions P1, P2, and P3. Meanwhile, as shown in FIGS. 13 and 14 , the second region RA2 and the third region RA3 each include one of the active portion P1 and the active portions P2 and P3, but not the other. Therefore, the second region RA2 is located closer to the X1 direction than the second region RA2 and functions as a relaxation region between the region without any active portions and the first region RA1, which includes all of the active portions P1, P2, and P3. The third region RA3 is located closer to the X2 direction than the third region RA3 and functions as a relaxation region between the region without any active portions and the first region RA1, which includes all of the active portions P1, P2, and P3. Here, the relaxation region refers to a region that relaxes structural discontinuities and electric field discontinuities along the X axis. The structural discontinuity refers to the change in the rigidity of the laminate of the piezoelectric element 51f and the diaphragm 51e depending on the presence or absence of various electrodes and the number of such electrodes, etc. The electric field discontinuity refers to the presence or absence of a potential difference applied to the piezoelectric layer 51f2, i.e., whether or not it is an active part, and the number of active parts provided.

[0109] Thus, in this embodiment, the second region RA2 and the third region RA3 function as relaxation regions. Therefore, as shown in the lower part of FIG. 12, the change in strain occurring in the diaphragm 51e relative to the position along the X-axis occurs in two stages, and the slope of the graph is relatively small. In other words, the steep change in strain of the diaphragm 51e near both ends of the active sections P1, P2, and P3 along the X-axis is reduced. As a result, the occurrence of localized stress in the diaphragm 51e near the ends of the active sections P1, P2, and P3 in the X1 direction is reduced. Similarly, the occurrence of localized stress in the diaphragm 51e near the ends of the active sections P1, P2, and P3 in the X2 direction is also reduced.

[0110] In contrast, in a configuration without the second region RA2 or the third region RA3, as shown in the upper part of FIG. 15, there is no region that functions as a relaxation region, resulting in increased structural discontinuity and electric field discontinuity. Therefore, as shown in the lower part of FIG. 15, the change in strain occurring in the diaphragm 51e with respect to position along the X-axis is not two-stage, and the slope of the graph is relatively steep. In other words, a steep change in strain occurs in the diaphragm 51e near the ends of the active sections P1, P2, and P3 in the X1 direction. As a result, stress is generated locally in the diaphragm 51e near the ends of the active sections P1, P2, and P3 in the X1 direction, which may cause damage such as cracks in the diaphragm 51e.

[0111] In the example shown in FIG. 12, the lengths L1, L2, and L3 of the active portions P1, P2, and P3 along the X axis are equal to each other. The active portions P2 and P3 are arranged so that their ends along the X axis are aligned. That is, the positions in the X1 direction of the end of the active portion P2 and the end of the active portion P3 are equal to each other. Similarly, the positions in the X2 direction of the end of the active portion P2 and the end of the active portion P3 are equal to each other. In contrast, the active portion P1 is arranged offset in the X2 direction relative to the active portions P2 and P3. The above-described arrangement of the active portions P1, P2, and P3 provides a first region RA1, a second region RA2, and a third region RA3.

[0112] When the length of the first region RA1 along the X1 direction or the X2 direction is defined as La, and the length of the second region RA2 along the X1 direction or the X2 direction is defined as Lb, it is preferable to satisfy the relationship of 0.025×La < Lb < 0.5×La. By satisfying the relationship of 0.025×La < Lb, damage such as cracks in the diaphragm 51e can be suitably reduced. Also, by satisfying the relationship of Lb < 0.5×La, sufficient displacement of the diaphragm 51e can be ensured. On the other hand, if the length Lb is too small, the effect of reducing damage such as cracks in the diaphragm 51e tends to decrease. On the contrary, if the length Lb is too large, it tends to be difficult to increase the displacement of the diaphragm 51e.

[0113] As described above, the liquid ejection head 50 includes a diaphragm 51e, a pressure chamber substrate 51b, and a piezoelectric element 51f. The diaphragm 51e has a first surface F1 and a second surface F2 facing in the opposite direction to the first surface F1. The pressure chamber substrate 51b is laminated on the first surface F1 and has a partition wall 51b1 that defines a pressure chamber C communicating with a nozzle N that ejects ink, which is an example of "liquid". When the piezoelectric element 51f partitions a region in the X1 direction or the X2 direction, it has an active part P1, which is an example of "the first active part", and an active part P2, which is an example of "the second active part", and is laminated on the second surface F2. The active part P1 and the active part P2 deform by the application of a voltage and are arranged at different positions.

[0114] Here, the lamination direction of the diaphragm 51e and the piezoelectric element 51f is the Z1 direction or the Z2 direction, which is an example of "the first direction". The direction in which the active part P1 and the active part P2 are arranged when viewed in the Z1 direction or the Z2 direction is the Y1 direction or the Y2 direction, which is an example of "the second direction". The direction orthogonal to the Z1 direction or the Z2 direction and the Y1 direction or the Y2 direction is the X1 direction or the X2 direction, which is an example of "the third direction".

[0115] At least a portion of each of the active portions P1 and P2 overlaps with the pressure chamber C when viewed in the Z1 or Z2 direction. Furthermore, the piezoelectric element 51f has a first region RA1 and a second region RA2. The first region RA1 is a region where both the active portion P1 and the active portion P2 are provided along the X1 or X2 direction. The second region RA2 is a region where one of the active portion P1 and the active portion P2 is provided along the X1 or X2 direction and the other is not provided along the X1 or X2 direction.

[0116] In the liquid ejection head 50 described above, both the active portion P1 and the active portion P2 are provided in the first region RA1, which allows ink to be ejected from the nozzles N more efficiently than in a configuration in which only the active portion P1 or the active portion P2 is provided across the entire area in the X1 or X2 direction. Moreover, because only one of the active portion P1 and the active portion P2 is provided in the second region RA2, it is possible to reduce stress that occurs locally in the vibration plate 51e when the piezoelectric element 51f is driven. This reduces damage such as cracks in the vibration plate 51e, thereby improving the reliability of the liquid ejection head 50.

[0117] As described above, the active part P2 is disposed at a position closer to the end of the pressure chamber C in the Y1 direction or the Y2 direction than the active part P1. On the other hand, the active part P1 is disposed at a position closer to the center of the pressure chamber C in the Y1 direction or the Y2 direction than the active part P2. With the active parts P1 and P2 disposed in this manner, the diaphragm 51e can be vibrated efficiently by supplying out-of-phase drive pulses to the active parts P1 and P2.

[0118] As described above, the piezoelectric element 51f further includes a third region RA3. The third region RA3 is a region where one of the active portion P1 and the active portion P2 is provided along the X1 direction or the X2 direction, and the other is not provided along the X1 direction or the X2 direction. The first region RA1 is a region between the second region RA2 and the third region RA3. This effectively reduces damage, such as cracks, to the vibration plate 51e.

[0119] Furthermore, as described above, in the second region RA2, the active part P2 is provided and the active part P1 is not provided. In the third region RA3, the active part P1 is provided and the active part P2 is not provided. Therefore, it becomes easy to draw out the individual wirings 51j and 51k for the active part P1 and the active part P2 in different directions from each other.

[0120] Also, as described above, the lengths of the second region RA2 and the third region RA3 along the X1 direction or the X2 direction are equal to each other. Therefore, compared with a configuration in which the lengths of the second region RA2 and the third region RA3 along the X1 direction or the X2 direction are different from each other, the symmetry of the shape of the piezoelectric element 51f can be enhanced. As a result, the diaphragm 51e can be vibrated stably.

[0121] Furthermore, as described above, when the length of the first region RA1 along the X1 direction or the X2 direction is La and the length of the second region RA2 along the X1 direction or the X2 direction is Lb, if the relationship 0.05×La < Lb is satisfied, damage such as cracks in the diaphragm 51e can be suitably reduced. On the other hand, if the length Lb is too small, the effect of reducing damage such as cracks in the diaphragm 51e tends to decrease.

[0122] Also, as described above, when the relationship Lb < 0.5×La is satisfied, sufficient displacement of the diaphragm 51e can be ensured. On the other hand, if the length Lb is too large, it tends to be difficult to increase the displacement of the diaphragm 51e.

[0123] Furthermore, as described above, the piezoelectric element 51f further has an active part P3 that is deformed by the application of a voltage. The active part P3 is disposed at a position closer to the end of the pressure chamber C in the Y1 direction or the Y2 direction than the active part P1. And the active part P1 is disposed between the active part P2 and the active part P3. Moreover, the first region RA1 is a region where all of the active part P1, the active part P2, and the active part P3 are provided. Therefore, the symmetry of the shape of the piezoelectric element 51f can be enhanced. As a result, the diaphragm 51e can be vibrated stably.

[0124] As described above, the X1-direction end of the active portion P2 and the X1-direction end of the active portion P3 are positioned at the same position in the X1 direction. Similarly, the X2-direction end of the active portion P2 and the X2-direction end of the active portion P3 are positioned at the same position in the X2 direction. By aligning the ends of the active portions P2 and P3 in this way, the symmetry of the shape of the piezoelectric element 51f can be improved. As a result, the vibration plate 51e can be vibrated stably.

[0125] Furthermore, as described above, the piezoelectric element 51f includes the second electrode layer 51f3, which is an example of a "common electrode," the piezoelectric layer 51f2, the individual electrode 51f11, which is an example of a "first individual electrode," and the individual electrode 51f12, which is an example of a "second individual electrode." The active portion P1 includes the piezoelectric layer 51f2, the individual electrode 51f11, and the second electrode layer 51f3, which overlap when viewed in the Z1 or Z2 direction. Meanwhile, the active portion P2 includes the piezoelectric layer 51f2, the individual electrode 51f12, and the second electrode layer 51f3, which overlap when viewed in the Z1 or Z2 direction. The positions of the X1-direction end of the individual electrode 51f11 and the X1-direction end of the individual electrode 51f12 are different from each other. Similarly, the positions of the X2-direction end of the individual electrode 51f11 and the X2-direction end of the individual electrode 51f12 are different from each other. By shifting the ends of the individual electrodes 51f11 and 51f12 from each other in this manner, the second electrode layer 51f3 can be provided over an area that includes the active portions P1 and P2 in a plan view. Therefore, the second electrode layer 51f3 can be used as a protective layer for the piezoelectric layer 51f2.

[0126] As described above, the liquid ejection head 50 further includes individual wiring 51j, which is an example of a "first individual wiring," and individual wiring 51k, which is an example of a "second individual wiring." Individual wiring 51j is connected to individual electrode 51f11 at a position offset from the center of individual electrode 51f11 in the X1 or X2 direction. Individual wiring 51k is connected to individual electrode 51f12 at a position offset in the opposite direction from individual wiring 51j from the center of individual electrode 51f12 in the X1 or X2 direction. These connections make it easy to route the individual wirings 51j and 51k.

[0127] Furthermore, as described above, of the two ends of the second region RA2 in the X1 and X2 directions, the end farther from the first region RA1 overlaps with the pressure chamber C when viewed in the Z1 or Z2 direction. In this case, the effect of reducing damage such as cracks to the diaphragm 51e becomes significant.

[0128] Furthermore, as described above, when the period in which the active part P1 is driven and the period in which the active part P2 is driven at least partially overlap each other, the effect of reducing damage such as cracks in the diaphragm 51e becomes significant.

[0129] Furthermore, as described above, each of the individual electrodes 51f11 and 51f12 is interposed between the diaphragm 51e and the second electrode layer 51f3, so that the second electrode layer 51f3 can be used as a protective layer for the piezoelectric layer 51f2.

[0130] 2. Second embodiment A second embodiment of the present disclosure will be described below, focusing on the differences from the first embodiment.

[0131] 16 is a plan view of a head chip 51A of a liquid ejection head 50A according to the second embodiment. The liquid ejection head 50A is configured in the same manner as the liquid ejection head 50 of the first embodiment described above, except that it includes a head chip 51A instead of the head chip 51. The head chip 51A is similar to the head chip 51, except that it includes a first electrode layer 51f4 instead of the first electrode layer 51f1.

[0132] The first electrode layer 51f4 is configured similarly to the first electrode layer 51f1 except for the shape in plan view, and accordingly, the shapes of the active parts P1, P2, and P3 in this embodiment in plan view are different from those of the active parts P1, P2, and P3 in the first embodiment.

[0133] Specifically, the first electrode layer 51f4 has, for each piezoelectric element 51f, an individual electrode 51f41 which is an example of a "first individual electrode," an individual electrode 51f42 which is an example of a "second individual electrode," and an individual electrode 51f43 which is an example of a "third individual electrode."

[0134] The individual electrode 51f41 is configured similarly to the individual electrode 51f11 of the first embodiment, except that the end portion in the X2 direction is tapered toward the X2 direction. In the example shown in Fig. 16, the width of the individual electrode 51f41 along the Y axis at the end portion in the X2 direction continuously narrows toward the X2 direction. Note that the width of the individual electrode 51f41 along the Y axis at the end portion in the X2 direction may narrow in stages toward the X2 direction.

[0135] The individual electrode 51f42 is configured similarly to the individual electrode 51f12 of the first embodiment, except that its end in the X1 direction is tapered. In the example shown in FIG. 16, the width of the end in the X1 direction of the individual electrode 51f41 along the Y axis continuously narrows toward the X1 direction. Similarly, the individual electrode 51f43 is configured similarly to the individual electrode 51f13 of the first embodiment, except that its end in the X1 direction is tapered. Note that the width of each of the end in the X1 direction of the individual electrodes 51f42 and 51f43 along the Y axis may narrow stepwise toward the X1 direction.

[0136] 16, the range of the tapered portions of individual electrodes 51f42 and 51f43 along the X axis does not overlap with the range of the constant-width portion of individual electrode 51f41 along the X axis. This allows the first region RA1 to efficiently deform diaphragm 51e. However, these ranges may overlap.

[0137] Due to the planar shapes of the individual electrodes 51f41, 51f42, and 51f43 described above, the end of the active part P1 in the X2 direction tapers toward the X2 direction, and the end of each of the active parts P2 and P3 in the X1 direction tapers toward the X1 direction.

[0138] That is, the width of the end portion of the active portion P1 in the X2 direction narrows continuously in the X2 direction. The width of the end portion of each of the active portions P2 and P3 in the X1 direction narrows continuously in the X1 direction. Note that the width of the end portion of the active portion P1 in the X2 direction may narrow stepwise in the X2 direction. The width of the end portion of each of the active portions P2 and P3 in the X1 direction may narrow stepwise in the X1 direction.

[0139] 16, the tapered portion of the active portion P1 is included in the third region RA3. Furthermore, the tapered portions of the active portions P2 and P3 are included in the second region RA2. Note that a portion of the tapered portion of the active portion P1 may be included in the first region RA1, or a portion of the tapered portion of the active portions P2 and P3 may be included in the first region RA1.

[0140] The second embodiment described above also improves the reliability of the liquid ejection head 50A while allowing ink to be ejected efficiently from the nozzles N. In this embodiment, as described above, for each of the active portions P1, P2, and P3, the width in the Y1 or Y2 direction at the end in the X1 or X2 direction is narrower than the width in the Y1 or Y2 direction at the center in the X1 or X2 direction. This reduces stress generated in the diaphragm 51e between the active portions P1, P2, and P3 and the non-active portions. As a result, damage to the diaphragm 51e, such as cracks, can be effectively reduced. Note that one of the active portion P1 and the active portions P2 and P3 may have a constant width, as in the first embodiment.

[0141] 3. Third embodiment The third embodiment of the present disclosure will be described below, focusing on the differences from the first embodiment.

[0142] 17 is a diagram illustrating the first region RA1, second region RA2, and third region RA3 of a liquid ejection head 50B according to the third embodiment. The liquid ejection head 50B is configured similarly to the liquid ejection head 50 of the first embodiment, except that the length relationships along the X-axis of the active portions P1, P2, and P3 are different.

[0143] In the liquid ejection head 50B, the lengths L2 and L3 of the active portions P2 and P3 along the X axis are equal to each other. The active portions P2 and P3 are arranged so that their ends along the X axis are aligned. That is, the ends of the active portions P2 and P3 in the X1 and X2 directions are positioned equal to each other along the X axis. In contrast, the length L1 of the active portion P1 along the X axis is shorter than the lengths L2 and L3 of the active portions P2 and P3 along the X axis. The end of the active portion P1 in the X1 direction is located closer to the X2 direction than the ends of the active portions P2 and P3 in the X1 direction, and the end of the active portion P1 in the X2 direction is located closer to the X1 direction than the ends of the active portions P2 and P3 in the X2 direction. The above-described arrangement of the active portions P1, P2, and P3 provides a first region RA1, a second region RA2, and a third region RA3.

[0144] Here, the first region RA1 is provided with all of the active parts P1, P2, and P3, whereas the second region RA2 and the third region RA3 are provided with the active parts P2 and P3, respectively, but are not provided with the active part P1.

[0145] According to the third embodiment described above, ink can be efficiently ejected from the nozzles N while improving the reliability of the liquid ejection head 50B.

[0146] 4. Fourth embodiment The fourth embodiment of the present disclosure will be described below, focusing on the differences from the first embodiment.

[0147] 18 is a diagram illustrating the first region RA1, second region RA2, and third region RA3 of a liquid ejection head 50C according to the fourth embodiment. The liquid ejection head 50C is configured similarly to the liquid ejection head 50 of the first embodiment, except that the length relationships along the X-axis of the active portions P1, P2, and P3 are different.

[0148] In the liquid ejection head 50C, the lengths L2 and L3 of the active portions P2 and P3 along the X axis are equal to each other. The active portions P2 and P3 are arranged so that their ends along the X axis are aligned. That is, the ends of the active portions P2 and P3 in the X1 and X2 directions are positioned equal to each other along the X axis. In contrast, the length L1 of the active portion P1 along the X axis is longer than the lengths L2 and L3 of the active portions P2 and P3 along the X axis. The end of the active portion P1 in the X1 direction is located further in the X1 direction than the ends of the active portions P2 and P3 in the X1 direction, and the end of the active portion P1 in the X2 direction is located further in the X2 direction than the ends of the active portions P2 and P3 in the X2 direction. The above-described arrangement of the active portions P1, P2, and P3 provides a first region RA1, a second region RA2, and a third region RA3.

[0149] The first region RA1 is provided with all of the active parts P1, P2, and P3, whereas the second region RA2 and the third region RA3 are each provided with the active part P1 but not the active parts P2 or P3.

[0150] According to the fourth embodiment described above, ink can be efficiently ejected from the nozzles N while improving the reliability of the liquid ejection head 50C.

[0151] 5. Fifth embodiment The fifth embodiment of the present disclosure will be described below, focusing on the differences from the first embodiment.

[0152] 19 is a plan view of a head chip 51D of a liquid ejection head 50D according to the fifth embodiment. The liquid ejection head 50D is configured similarly to the liquid ejection head 50 of the first embodiment described above, except that it includes a head chip 51D instead of the head chip 51. The head chip 51D is similar to the head chip 51, except that it includes a first electrode layer 51f5 instead of the first electrode layer 51f1 and a second electrode layer 51f6 instead of the second electrode layer 51f3. The second electrode layer 51f6 is an example of a "common electrode."

[0153] The first electrode layer 51f5 has the same configuration as the first electrode layer 51f1 except for its different shape in a plan view. Specifically, the first electrode layer 51f5 has, for each piezoelectric element 51f, an individual electrode 51f51 that is an example of a "first individual electrode," an individual electrode 51f52 that is an example of a "second individual electrode," and an individual electrode 51f53 that is an example of a "third individual electrode."

[0154] The individual electrodes 51f51, 51f52, and 51f53 are configured in the same manner as the individual electrodes 51f11, 51f12, and 51f13 of the first embodiment, except that they are arranged so that both ends thereof in the direction along the X axis are aligned with each other. That is, the individual electrodes 51f51, 51f52, and 51f53 have the same length in the direction along the X axis, and are arranged so that both ends thereof in the direction along the X axis are aligned with each other.

[0155] The second electrode layer 51f6 has the same configuration as the second electrode layer 51f3 of the first embodiment, except for its shape in a plan view. The second electrode layer 51f6 has a shape in which portions overlapping both ends of the individual electrode 51f51 in the X1 and X2 directions are cut out in a plan view. This provides a first region RA1, a second region RA2, and a third region RA3.

[0156] Here, the first region RA1 is provided with all of the active parts P1, P2, and P3, whereas the second region RA2 and the third region RA3 are provided with the active parts P2 and P3, respectively, but are not provided with the active part P1.

[0157] The fifth embodiment described above also improves the reliability of the liquid ejection head 50D while allowing ink to be efficiently ejected from the nozzles N. In this embodiment, as described above, the piezoelectric element 51f includes a second electrode layer 51f6, which is an example of a "common electrode," a piezoelectric layer 51f2, an individual electrode 51f51, which is an example of a "first individual electrode," and an individual electrode 51f52, which is an example of a "second individual electrode." In the active portion P1, the piezoelectric layer 51f2, the individual electrode 51f51, and the second electrode layer 51f6 overlap when viewed in the Z1 or Z2 direction. Meanwhile, in the active portion P2, the piezoelectric layer 51f2, the individual electrode 51f52, and the second electrode layer 51f6 overlap when viewed in the Z1 or Z2 direction. Furthermore, in the first region RA1, the second electrode layer 51f6 is provided over the individual electrodes 51f51 and 51f52. In the second region RA2, the second electrode layer 51f6 is provided on one of the individual electrodes 51f51 and 51f52, but not on the other. Therefore, even if the individual electrodes 51f51 and 51f52 are aligned in the longitudinal direction, the active portions P1 and P2 can be shifted in the longitudinal direction.

[0158] 6. Variations Each of the above-mentioned exemplary embodiments can be modified in various ways. Specific modified embodiments that can be applied to each of the above-mentioned embodiments are exemplified below. Two or more embodiments arbitrarily selected from the following examples can be appropriately combined within the scope of not contradicting each other.

[0159] 6-1. Variation 1 In the above embodiment, the waveform of the first drive signal Com-A used to drive the active unit P1 and the waveform of the second drive signal Com-B used to drive the active units P2 and P3 are the same, but this is not limiting and these waveforms may be different from each other. Also, a constant potential may be supplied to the active units P2 and P3 instead of the second drive signal Com-B.

[0160] 6-2. Variation 2 In the above-described embodiment, a configuration in which a piezoelectric layer is interposed between an individual electrode and a common electrode is exemplified, but this is not limitative, and a configuration in which a piezoelectric layer is interposed between individual electrodes may also be used.

[0161] 6-3. Variation 3 In the above embodiment, the planar shape of the pressure chamber C is a parallelogram, and the active portions P1, P2, and P3 are rectangular, but the present invention is not limited to this, and the planar shape of the pressure chamber C may be circular, elliptical, horseshoe, rhombus, etc. In such cases, the active portions P1, P2, and P3 may be changed to various shapes other than rectangular, depending on the planar shape of the pressure chamber C.

[0162] 6-4. Variation 4 In each of the above-mentioned embodiments, a serial-type liquid ejection device 100 is exemplified, in which a carriage 41 carrying a liquid ejection head 50 moves back and forth, but the present disclosure can also be applied to a line-type liquid ejection device in which multiple nozzles N are distributed across the entire width of the medium M.

[0163] 6-5. Variation 5 The liquid ejection device 100 exemplified in each of the above-described embodiments 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 disclosure 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 on a wiring board. [Explanation of symbols]

[0164] 10...liquid container, 20...control unit, 21...control circuit, 22...memory circuit, 23...power supply circuit, 24...drive signal generation circuit, 30...transport mechanism, 40...movement mechanism, 41...carriage, 42...transport belt, 50...liquid ejection head, 50A...liquid ejection head, 50B...liquid ejection head, 50C...liquid ejection head, 50D...liquid ejection head, 51...head chip, 51A...head chip, 51D...head chip, 51a...flow path substrate, 51b...pressure chamber substrate, 51b1...partition wall, 51c...nozzle plate, 51d...vibration absorber, 51e...vibration plate, 51e1...first layer, 51e2...second layer, 51f...piezoelectric element, 51f1...first electrode layer, 51f11...individual electrode (first individual electrode), 51f12...individual electrode (second individual electrode), 51f13...individual electrode (third individual electrode), 51f2...piezoelectric layer, 51f3...second electrode layer (common electrode), 51f4...first electrode layer, 51f41...individual electrode (first individual electrode), 51f42...individual electrode (second individual electrode), 51f43...individual electrode (third individual electrode), 51f5...first electrode layer, 51f51...individual electrode (first individual electrode), 51f52...individual electrode (second individual electrode), 51f53...individual electrode (third individual electrode), 51f6...second electrode layer (common electrode), 51g...cover, 51h...case, 51i...wiring board, 51j...individual wiring (first individual wiring), 51k...individual wiring (second individual wiring), 52...switching circuit, 52a...connection state designation circuit, 100...liquid ejection device, 200...external device, ABO3...general composition formula, BD...outer edge, C...pressure chamber, CLK...clock signal, CNG...change signal, Com-A...first drive signal, Com-B...second drive signal, EEa...expansion element, EEb...expansion element, ERa...retention element, ERb...retention element, ESa...contraction element, ESb...contraction element, F1...first surface, F2...second surface, IH... Inlet, Img...print data, LAT...latch signal, LHa...wiring, LHb...wiring, LHd...wiring, M...medium, N...nozzle, Na...communicating flow path, P1...active portion (first active portion), P1a...period, P1b...period, P2...active portion (second active portion), P2a...period, P2b...period, P3...active portion (third active portion), P3a...period, P3b...period, P4a...period, P4b...period, P5a...period, P5b...period, PS...period, R...liquid storage chamber, R1...opening, R2...storage portion, RA1...first area, RA2...second area, RA3...third area, Ra...supply flow path, SI...print data signal,SLa...connection state designation signal, SS...contraction process, SWa...switch, SWb...switch, Sk1...control signal, Sk2...control signal, Tu...unit period, VBS...offset potential, VHV...power supply potential, VHa...potential, VHb...potential, Vca...intermediate potential, Vcb...intermediate potential, Vin-A...supply signal, Vin-B...supply signal, W1...width, W2...width, W3...width, dCom...waveform designation signal.

Claims

1. a diaphragm having a first surface and a second surface facing in a direction opposite to the first surface; a pressure chamber substrate laminated on the first surface and having partition walls that define pressure chambers communicating with nozzles that eject liquid; a piezoelectric element that is deformed by application of a voltage and has a first active portion and a second active portion that are disposed at different positions from each other, and is laminated on the second surface; a lamination direction of the vibration plate and the piezoelectric element is a first direction; a direction in which the first active unit and the second active unit are arranged side by side as viewed in the first direction is defined as a second direction; When a direction perpendicular to the first direction and the second direction is defined as a third direction, At least a portion of each of the first active portion and the second active portion overlaps with the pressure chamber when viewed in the first direction; When the piezoelectric element defines a region in the third direction, a first region in which both the first active unit and the second active unit are provided; a second region in which one of the first active section and the second active section is provided and the other is not provided; A liquid ejection head comprising:

2. the second active portion is disposed at a position closer to an end of the pressure chamber in the second direction than the first active portion, the first active portion is disposed at a position closer to a center of the pressure chamber in the second direction than the second active portion; 2. The liquid ejection head according to claim 1.

3. When the piezoelectric element defines a region in the third direction, a third region in which one of the first active section and the second active section is provided and the other is not provided, The first region is a region between the second region and the third region.

3. The liquid ejection head according to claim 1, wherein the liquid ejection head is a liquid ejection head.

4. the second region is provided with the second active unit and is not provided with the first active unit; the third region is provided with the first active unit and is not provided with the second active unit; 4. The liquid ejection head according to claim 3.

5. the second region is provided with the second active unit and is not provided with the first active unit; the third region is provided with the second active unit and is not provided with the first active unit; 4. The liquid ejection head according to claim 3.

6. the second region is provided with the first active portion and is not provided with the second active portion; the third region is provided with the first active unit and is not provided with the second active unit; 4. The liquid ejection head according to claim 3.

7. The lengths of the second region and the third region in the third direction are equal to each other.

7. The liquid ejection head according to claim 3, wherein the liquid ejection head is a liquid ejection head.

8. When the length of the first region in the third direction is La and the length of the second region along the third direction is Lb, The relationship of 0.025×La<Lb is satisfied.

8. The liquid ejection head according to claim 1, wherein the liquid ejection head is a liquid ejection head.

9. When the length of the first region in the third direction is La and the length of the second region in the third direction is Lb, The relationship Lb<0.5×La is satisfied.

9. The liquid ejection head according to claim 1,

10. The piezoelectric element further includes a third active portion that is deformed by application of a voltage, the third active portion is disposed at a position closer to an end of the pressure chamber in the second direction than the first active portion; the first active unit is disposed between the second active unit and the third active unit in the second direction; the first region is a region in which the first active unit, the second active unit, and the third active unit are all provided; 10. The liquid ejection head according to claim 1,

11. an end of the second active portion in the third direction and an end of the third active portion in the third direction are positioned equal to each other in the third direction; 11. The liquid ejection head according to claim 10.

12. For one or both of the first active portion and the second active portion, a width in the second direction at an end in the third direction is narrower than a width in the second direction at a center in the third direction.

12. The liquid ejection head according to claim 1,

13. The piezoelectric element is A common electrode; A piezoelectric layer; A first individual electrode; a second individual electrode; the first active portion has the piezoelectric layer, the first individual electrode, and the common electrode overlapping each other when viewed in the first direction; the second active portion has the piezoelectric layer, the second individual electrode, and the common electrode overlapping each other when viewed in the first direction, In the first region, the common electrode is provided across the first individual electrode and the second individual electrode, In the second region, the common electrode is provided on one of the first individual electrode and the second individual electrode, but not on the other of the first individual electrode and the second individual electrode.

13. The liquid ejection head according to claim 1,

14. The piezoelectric element is A common electrode; A piezoelectric layer; A first individual electrode; a second individual electrode; the first active portion has the piezoelectric layer, the first individual electrode, and the common electrode overlapping each other when viewed in the first direction; the second active portion has the piezoelectric layer, the second individual electrode, and the common electrode overlapping each other when viewed in the first direction, an end of the first individual electrode in the third direction and an end of the second individual electrode in the third direction are positioned differently in the third direction; 13. The liquid ejection head according to claim 1, 15. The piezoelectric element according to claim 1, further comprising: a common electrode; a piezoelectric layer; a first individual electrode; and a second individual electrode. a first individual wiring connected to the first individual electrode at a position shifted from a center of the first individual electrode in the third direction; a second individual wiring connected to the second individual electrode at a position shifted in a direction opposite to the first individual wiring from a center of the second individual electrode in the third direction, 13. The liquid ejection head according to claim 1,

16. an end of the second region farther from the first region in the third direction and in the direction opposite to the third direction overlaps with the pressure chamber when viewed in the first direction; 16. The liquid ejection head according to claim 1,

17. At least a part of a period in which the first active unit is driven and a part of a period in which the second active unit is driven overlap each other.

17. The liquid ejection head according to claim 1, 18. The piezoelectric element includes a common electrode, a piezoelectric layer, a first individual electrode, and a second individual electrode, each of the first individual electrode and the second individual electrode is interposed between the vibration plate and the common electrode in the first direction; At least a part of a period in which the first active unit is driven and a part of a period in which the second active unit is driven overlap each other.

13. The liquid ejection head according to claim 1,

19. A liquid ejection head according to any one of claims 1 to 18, a drive signal generating unit that generates a first drive signal that drives the first active unit and a second drive signal that drives the second active unit; A liquid ejection device comprising:

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