Liquid discharge device

Abstract

To provide a liquid discharge device improved in discharge characteristics.SOLUTION: The liquid discharge device comprises: a pressure chamber substrate, which is laminated on a first surface of a vibration plate, and has a bulkhead partitioning a pressure chamber communicating with a nozzle for discharging liquid; a piezoelectric element, which is laminated on a second surface of the vibration plate, and has a first active part overlapping with a center of the pressure chamber when viewed in a thickness direction of the vibration plate and a second active part overlapping with the pressure chamber, at a position closer to an outer edge of the pressure chamber than the first active part; a driving signal generating part that generates a first driving signal for driving the first active part and a second driving signal for driving the second active part. The first driving signal includes a first contractile element for contracting a volume of the pressure chamber for each periodic unit period, and the second driving signal includes a second contractile element for contracting the volume of the pressure chamber for unit period. The liquid discharge device executes a contraction process in which a first period during which the first contractile element is supplied to the first acting part and a second period during which the second contractile element is supplied to the second acting part overlap with each other.SELECTED DRAWING: Figure 9

Description

Technical Field

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

Background Art

[0002] A liquid ejection device typified by a piezoelectric inkjet printer generally employs a configuration in which a piezoelectric element is disposed on a diaphragm that forms part of the wall surface of a pressure chamber communicating with a nozzle. Here, a liquid such as ink is stored in the pressure chamber. Then, the piezoelectric element causes the diaphragm to deform, thereby ejecting the liquid from the nozzle along with the expansion or contraction of the volume of the pressure chamber.

[0003] The piezoelectric element of such a liquid ejection device may be divided, for example, as disclosed in Patent Document 1, into an active portion that overlaps the central portion of the pressure chamber and an active portion that overlaps the end portion of the pressure chamber when viewed in the thickness direction of the diaphragm.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, Patent Document 1 does not disclose a specific drive signal for driving each of the above-described two active portions. Under such circumstances, it is desired to realize a liquid ejection device having excellent ejection characteristics.

Means for Solving the Problems

[0006] To solve the above problems, one embodiment of a liquid discharge device according to the present disclosure includes: a diaphragm having a first surface and a second surface facing in the opposite direction to the first surface; a pressure chamber substrate laminated on the first surface and having a partition wall that divides a pressure chamber communicating with a nozzle for discharging liquid; a piezoelectric element laminated on the second surface and having a first active part that overlaps the center of the pressure chamber when viewed in the thickness direction of the diaphragm and a second active part that overlaps the pressure chamber at a position closer to the outer edge of the pressure chamber than the first active part; and a drive for the first active part The system includes a drive signal generation unit that generates a first drive signal and a second drive signal that drives the second active unit, wherein the first drive signal includes a first contraction element that reduces the volume of the pressure chamber at periodic unit intervals, and the second drive signal includes a second contraction element that reduces the volume of the pressure chamber at period intervals, and performs a contraction process in which a first period in which the first contraction element is supplied to the first active unit and a second period in which the second contraction element is supplied to the second active unit overlap.

[0007] Another embodiment of the liquid discharge device according to the present disclosure comprises: a diaphragm having a first surface and a second surface facing in the opposite direction to the first surface; a pressure chamber substrate laminated on the first surface and having a partition wall that demarcates a pressure chamber communicating with a nozzle for discharging liquid; a piezoelectric element laminated on the second surface and having a first active portion that overlaps the center of the pressure chamber when viewed in the thickness direction of the diaphragm and a second active portion that overlaps the pressure chamber at a position closer to the outer edge of the pressure chamber than the first active portion; and a drive signal generation unit that generates a first drive signal for driving the first active portion and a second drive signal for driving the second active portion, wherein the first drive signal includes a first period in which it changes from a first potential to a second potential for each period of time, and the second drive signal includes a second period in which it changes from a third potential to a fourth potential for each period of time, and the first period and the second period overlap each other. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing a liquid dispensing device according to the first embodiment. [Figure 2]This figure shows the electrical configuration of the liquid dispensing device according to the first embodiment. [Figure 3] This is a disassembled perspective view of the head chip. [Figure 4] This is a cross-sectional view along line AA in Figure 3. [Figure 5] This is a plan view of the head tip. [Figure 6] This is a cross-sectional view along line BB in Figure 5. [Figure 7] This is a diagram illustrating a switching circuit. [Figure 8] This is a diagram illustrating the first drive signal and the second drive signal in the first embodiment. [Figure 9] This is a diagram illustrating the shrinkage process in the first embodiment. [Figure 10] This is a schematic diagram illustrating the deformation of the diaphragm caused by the first drive signal. [Figure 11] This is a schematic diagram illustrating the deformation of the diaphragm caused by the second drive signal. [Figure 12] This is a diagram illustrating the shrinkage process in the second embodiment. [Figure 13] This is a diagram illustrating the first drive signal and the second drive signal in the third embodiment. [Figure 14] This is a diagram illustrating the shrinking and expanding processes in the third embodiment. [Figure 15] This is a diagram illustrating the shrinking and expanding processes in the fourth embodiment. [Figure 16] This figure illustrates the contraction process, expansion process, and vibration damping process in the fifth embodiment. [Figure 17] This is a diagram illustrating the first drive signal and the second drive signal in the sixth embodiment. [Figure 18] This is a diagram illustrating the contraction and expansion processes in the sixth embodiment. [Figure 19] This is a diagram illustrating the contraction and expansion processes in the seventh embodiment. [Figure 20] This figure illustrates the first drive signal and the second drive signal in the eighth embodiment. [Figure 21] This is a diagram for explaining the contraction process, the first expansion process, and the second expansion process in the eighth embodiment. [Figure 22] This is a diagram for explaining the contraction process, the first expansion process, and the second expansion process in the ninth embodiment. [Figure 23] This is a diagram for explaining the contraction process and the expansion process in the tenth embodiment. [Figure 24] This is a diagram for explaining the contraction process and the expansion process in Modification 1.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, preferred embodiments according to the present disclosure will be described with reference to the accompanying drawings. Note that the dimensions and scales of each part in the drawings are appropriately different from the actual ones, and there are also parts schematically shown for easy understanding. Further, the scope of the present disclosure is not limited to these embodiments unless there is a description specifically limiting the present disclosure in the following description.

[0010] In the following description, for convenience, the X-axis, Y-axis, and Z-axis that intersect each other are appropriately used. Further, hereinafter, one direction along the X-axis is the X1 direction, and the direction opposite to the X1 direction is the X2 direction. Similarly, the directions opposite to each other along the Y-axis are the Y1 direction and the Y2 direction. Also, the directions opposite to each other along the Z-axis are the Z1 direction and the Z2 direction. Also, when looking in the direction along the Z-axis, it may be referred to as "plan view".

[0011] Here, typically, the Z-axis is a vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. However, the Z-axis does not have to be a vertical axis. Also, the X-axis, Y-axis, and Z-axis typically intersect each other at right angles, but are not limited thereto, and for example, they may intersect at an angle within the range of 80° or more and 100° or less.

[0012] 1. First Embodiment 1-1. Overall Configuration of the Liquid Discharge Device Figure 1 is a schematic diagram showing a liquid dispensing device 100 according to the first embodiment. The liquid dispensing device 100 is an inkjet printing device that dispenses ink, which is 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 any material to be printed on, such as a resin film or a cloth.

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

[0014] The liquid container 10 is a container for storing ink. Specific examples of the liquid container 10 include a cartridge that can be attached to or detached from the liquid dispensing device 100, a bag-shaped ink pack made of a 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, for example, a processing circuit such as a CPU (Central Processing Unit) or FPGA (Field Programmable Gate Array) and a storage circuit such as a semiconductor memory, and controls the operation of each element of the liquid dispensing device 100.

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

[0017] The liquid dispensing head 50, under the control of the control unit 20, dispenses ink supplied from the liquid container 10 from each of its multiple nozzles toward the medium M in the Z2 direction. This dispensing occurs in parallel with the transport of the medium M by the transport mechanism 30 and the reciprocating movement of the liquid dispensing head 50 by the moving mechanism 40, thereby forming an image on the surface of the medium M with ink.

[0018] 1-2. Electrical configuration of the liquid dispensing device Figure 2 shows the electrical configuration of the liquid dispensing device 100 according to the first embodiment. The control unit 20 will be described below based on Figure 2, but before that, the liquid dispensing head 50 will be briefly described.

[0019] As shown in Figure 2, the liquid discharge head 50 has a head tip 51 and a switching circuit 52.

[0020] The print head 51 has multiple piezoelectric elements 51f, and ink is ejected from the nozzle by appropriately driving these piezoelectric elements 51f. Here, each piezoelectric element 51f has an active part P1 which is an example of a "first active part", an active part P2 which is an example of a "second active part", and an active part P3 which is an example of a "third active part". Active part P1 is driven by the supply signal Vin-A. On the other hand, active parts P2 and P3 are driven by the supply signal Vin-B. Details of the print head 51 will be explained later with reference to Figures 3 to 6.

[0021] The switching circuit 52, under the control of the control unit 20, 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. Details of the switching circuit 52 will be explained later with reference to Figure 7.

[0022] In the example shown in Figure 2, the liquid discharge head 50 has one head tip 51, but this is not limited to this, and the liquid discharge head 50 may have two or more head tips 51.

[0023] As shown in Figure 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 unit".

[0024] The control circuit 21 has the function of controlling the operation of each part of the liquid dispensing device 100 and the function of processing various data. The control circuit 21 includes, for example, one or more processors such as CPUs (Central Processing Units). The control circuit 21 may also include a programmable logic device such as an FPGA (field-programmable gate array) instead of a CPU, or in addition to a CPU. Furthermore, if the control circuit 21 is composed of multiple processors, these 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: volatile memory such as RAM (Random Access Memory) and 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 also be configured as part of the control circuit 21.

[0026] The power supply circuit 23 receives power from a commercial power source (not shown) and generates various predetermined potentials. The generated potentials are supplied to various parts of the liquid dispensing 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 dispensing head 50. The power supply potential VHV is supplied to the drive signal generation circuit 24.

[0027] The drive signal generation circuit 24 is a circuit that generates a first drive signal Com-A and a second drive signal Com-B. Specifically, the drive signal generation circuit 24 includes, for example, a DA conversion circuit and an amplification 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 amplification 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. Here, the waveform signal that is actually supplied to the active part P1 of the piezoelectric element 51f from the waveforms included in the first drive signal Com-A is the aforementioned supply signal Vin-A. The waveform signal that is actually supplied to the active part P2 or active part P3 of the piezoelectric element 51f from the waveforms included in the second drive signal Com-B is the aforementioned supply signal Vin-B. The waveform specification signal dCom is a digital signal for defining the waveforms of the first drive signal Com-A and the second drive signal Com-B.

[0028] The control circuit 21 controls the operation of each part of the liquid dispensing device 100 by executing a program stored in the memory circuit 22. In this case, the control circuit 21 generates control signals Sk1 and Sk2, a print data signal SI, a waveform specification signal dCom, a latch signal LAT, a change signal CNG, and a clock signal CLK as signals to control the operation of each part of the liquid dispensing device 100 by executing the program.

[0029] Control signal Sk1 is a signal for controlling the drive of the transport mechanism 30. Control signal Sk2 is a signal for controlling the drive of the moving 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 define 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.

[0030] 1-3. Overall configuration of the liquid dispensing head

[0031] Figure 3 is an exploded perspective view of the head chip 51. Figure 4 is a cross-sectional view taken along line AA in Figure 3. As shown in Figures 3 and 4, the head chip 51 includes a flow channel 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 board 51i.

[0032] Here, the region located in the Z1 direction from the flow channel substrate 51a is equipped with a pressure chamber substrate 51b, a diaphragm 51e, a plurality of piezoelectric elements 51f, a case 51h, and a cover 51g. On the other hand, the region located in the Z2 direction from the flow channel substrate 51a is equipped with a nozzle plate 51c and a vibration absorber 51d. Each element of the liquid discharge head 50 is generally a long plate-like member along the Y axis, and is joined to each other, for example, by adhesive.

[0033] As shown in Figure 3, the nozzle plate 51c is a plate-shaped member provided with a plurality of nozzles N arranged in the direction along the Y axis. Each nozzle N is a through-hole through which ink passes. The nozzle plate 51c is manufactured by processing a silicon single crystal substrate using semiconductor manufacturing technology, such as dry etching or wet etching. However, other known methods and materials may be used in the manufacture of the nozzle plate 51c as appropriate.

[0034] The flow channel substrate 51a is a plate-shaped member for forming ink flow channels. As shown in Figures 2 and 3, the flow channel substrate 51a is provided with an opening R1, a plurality of supply flow channels Ra, and a plurality of communication flow channels Na. The opening R1 is a long through-hole that extends in the direction along the Y-axis in a plan view along the Z-axis, so as to be continuous across a plurality of nozzles N. On the other hand, the supply flow channels Ra and communication flow channels Na are through-holes provided individually for each nozzle N. Each of the plurality of supply flow channels Ra communicates with the opening R1. The flow channel substrate 51a is manufactured, for example, by processing a silicon single crystal substrate using semiconductor manufacturing technology, similar to the nozzle plate 51c described above. However, other known methods and materials may be used as appropriate for the manufacture of the flow channel substrate 51a. Note that a portion of the supply flow channels Ra may be formed in the pressure chamber substrate 51b.

[0035] The pressure chamber substrate 51b is a plate-shaped member on which multiple pressure chambers C corresponding to multiple nozzles N are formed. The pressure chamber C is located between the flow channel substrate 51a and the diaphragm 51e and is a space called a cavity for applying pressure to the ink filled in the pressure chamber C. The multiple pressure chambers C are arranged in the direction along the Y axis. Each pressure chamber C is composed of holes opening on both sides of the pressure chamber substrate 51b and has a long shape extending in the direction along the X axis. The end of each pressure chamber C in the X2 direction communicates with the corresponding supply flow channel Ra. The supply flow channel Ra has a narrower cross-sectional area than the pressure chamber C, and this part functions as flow resistance, thereby suppressing backflow when pressure is applied to the ink. On the other hand, the end of each pressure chamber C in the X1 direction communicates with the corresponding communication channel Na. The pressure chamber substrate 51b is manufactured, for example, by processing a silicon single crystal substrate using semiconductor manufacturing technology, similar to the nozzle plate 51c described above. However, other known methods and materials may be used as appropriate for the manufacture of each of the pressure chamber substrates 51b.

[0036] A diaphragm 51e is positioned on the surface of the pressure chamber substrate 51b facing the Z1 direction. The diaphragm 51e is an elastically deformable plate-shaped member. In the example shown in Figure 4, the diaphragm 51e has a first layer 51e1 which is an elastic film and a second layer 51e2 which is an insulating film, and these are stacked in this order in the Z1 direction. Details of the diaphragm 51e will be explained later based on Figure 6.

[0037] Multiple piezoelectric elements 51f, corresponding to different nozzles N or pressure chambers C, are arranged on the surface of the diaphragm 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 a long, elongated shape extending along the X-axis. The multiple piezoelectric elements 51f are arranged along the Y-axis to correspond to multiple pressure chambers C. When the diaphragm 51e vibrates in conjunction with the deformation of the piezoelectric elements 51f, the pressure in the pressure chamber C fluctuates, causing ink to be ejected from the nozzle N. Details of the piezoelectric elements 51f will be explained later with reference to Figure 6.

[0038] Case 51h is a case for storing ink supplied to multiple pressure chambers C, and is bonded to the surface of the flow channel substrate 51a facing the Z1 direction by adhesive or the like. Case 51h is made of, for example, a resin material and is manufactured by injection molding. Case 51h is provided with a housing section R2 and an inlet IH. Housing section R2 is a recess with an outer shape corresponding to the opening R1 of the flow channel substrate 51a. Inlet IH is a through hole communicating with housing section R2. The space formed by the opening R1 and housing section R2 functions as a liquid storage chamber R, which is a reservoir for storing ink. Ink from the liquid container 10 is supplied to the liquid storage chamber R through the inlet IH.

[0039] The vibration absorber 51d is an element for absorbing pressure fluctuations in the liquid storage chamber R. The vibration absorber 51d is, for example, a compliance substrate which is an elastically deformable flexible sheet member. Here, the vibration absorber 51d is positioned on the surface of the flow channel substrate 51a facing the Z2 direction so as to block the opening R1 of the flow channel substrate 51a and the plurality of supply channels Ra, thereby forming the bottom surface of the liquid storage chamber R.

[0040] 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 diaphragm 51e. The cover 51g is bonded to the surface of the diaphragm 51e, for example, by adhesive. The cover 51g is provided with recesses for housing the multiple piezoelectric elements 51f.

[0041] A wiring board 51i is bonded to the surface of the pressure chamber substrate 51b or the diaphragm 51e facing the Z1 direction. The wiring board 51i is a mounting component on which multiple wirings for electrically connecting the control unit 20 and the liquid discharge head 50 are formed. The wiring board 51i is a flexible wiring board such as an FPC (Flexible Printed Circuit) or FFC (Flexible Flat Cable). A switching circuit 52 is mounted on the wiring board 51i.

[0042] 1-4. Details of the diaphragm and piezoelectric element Figure 5 is a plan view of the head chip 51. Figure 6 is a cross-sectional view of line BB in Figure 5. In Figure 5, the plan view shape of the pressure chamber C is shown by the dashed line. Between two adjacent pressure chambers C on the pressure chamber substrate 51b, a wall-like partition wall 51b1 extending along the X direction is provided. The partition wall 51b1 divides the pressure chamber C.

[0043] In the example shown in Figure 5, the plan view shape of the pressure chamber C is a parallelogram. A pressure chamber C with such a plan view shape is formed, for example, by anisotropic etching of a silicon single crystal substrate with a (110) orientation. For the etching solution used in this anisotropic etching, for example, an aqueous potassium hydroxide solution (KOH) is used. In this anisotropic etching, the first layer 51e1 of the diaphragm 51e is used as an etching stop layer. Note that the plan view shape of the pressure chamber C is not limited to the example shown in Figure 5 and can be arbitrary.

[0044] As shown in Figure 6, the diaphragm 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 Figure 6, the thickness direction of the diaphragm 51e is along the Z-axis. Therefore, the first surface F1 is the surface of the diaphragm 51e facing the Z2 direction, and the second surface F2 is the surface of the diaphragm 51e facing the Z1 direction. A piezoelectric element 51f is placed on the second surface F2. A pressure chamber substrate 51b is placed on the first surface F1.

[0045] The diaphragm 51e has a first layer 51e1 and a second layer 51e1, which are stacked in this order in the Z1 direction. The first layer 51e1 is an elastic film composed of, for example, silicon oxide (SiO2). This elastic film is formed, for example, by thermal oxidation of one side of a silicon single crystal substrate. The second layer 51e1 is an insulating film composed of, for example, zirconium oxide (ZrO2). This insulating film is formed, for example, by forming a zirconium layer by sputtering and then thermally oxidizing the layer.

[0046] The first layer 51e1 is not limited to silicon oxide, but may be composed of other elastic materials such as pure silicon. The constituent material of the second layer 51e1 is not limited to zirconium oxide, but may be other insulating materials such as silicon nitride. Furthermore, other layers such as metal oxides may be interposed between the first layer 51e1 and the second layer 51e1. In other words, the first layer 51e1 or the second layer 51e1 may be composed of multiple layers that are identical or different from each other. Also, part or all of the diaphragm 51e may be integrally constructed from the same material as the pressure chamber substrate 51b. Furthermore, the diaphragm 51e may be composed of layers of a single material.

[0047] As shown in Figure 5, the piezoelectric element 51f overlaps the pressure chamber C in a plan view. As shown in Figure 6, the piezoelectric element 51f has a first electrode layer 51f1, a piezoelectric body layer 51f2, and a second electrode layer 51f3, which are stacked in this order in the Z1 direction.

[0048] Furthermore, other layers, such as layers to improve adhesion, may be appropriately interposed between the layers of the piezoelectric element 51f, or between the piezoelectric element 51f and the diaphragm 51e. In addition, a seed layer may be provided between the first electrode layer 51f1 and the piezoelectric layer 51f2. This seed layer has the function of improving the orientation of the piezoelectric layer 51f2 when it is formed. The seed layer may be composed of, for example, titanium (Ti) or a composite oxide having a perovskite structure such as Pb(Fe,Ti)O3. When the seed layer is composed of titanium, island-shaped Ti acts as crystal nuclei when the piezoelectric layer 51f2 is formed, 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 by, for example, known film deposition techniques such as sputtering, and known processing techniques such as photolithography and etching. Furthermore, when the seed layer is composed of the composite oxide, the orientation of the piezoelectric layer 51f2 is improved because the piezoelectric layer 51f2 is influenced by the crystal structure of the seed layer during its formation. In this case, the seed layer is formed, for example, by forming a precursor layer of the composite oxide using the sol-gel method or the MOD (metal-organic decomposition) method, and then crystallizing the precursor layer by firing.

[0049] The first electrode layer 51f1 has individual electrodes 51f1a, 51f1b, and 51f1c for each piezoelectric element 51f. Each of the individual electrodes 51f1a, 51f1b, and 51f1c extends in the direction along the X-axis. The individual electrodes 51f1a, 51f1b, and 51f1c are arranged in the direction along the Y-axis with spacing between them.

[0050] Here, individual electrode 51f1a is positioned in the center of the width direction of the pressure chamber C in a plan view, and overlaps with the center of the pressure chamber C. Individual electrode 51f1a is supplied with a first drive signal Com-A via wiring. On the other hand, individual electrodes 51f1b and 51f1c are positioned at the ends of the width direction of the pressure chamber C in a plan view, and overlap the pressure chamber C at a position closer to the outer edge BD of the pressure chamber C than individual electrode 51f1a. Individual electrodes 51f1b and 51f1c are supplied with a second drive signal Com-B via wiring.

[0051] The first electrode layer 51f1 includes, 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, known film deposition techniques such as sputtering, and known processing techniques such as photolithography and etching.

[0052] Here, the aforementioned first layer of the first electrode layer 51f1 functions as an adhesion layer to improve the 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 constituent material of the first layer is not limited to titanium, and for example, chromium may be used instead of titanium.

[0053] 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 have similar chemical properties. Therefore, the electrode properties of the first electrode layer 51f1 can be made excellent. The thickness of the second layer is not particularly limited, but for example, it is about 50 nm to 200 nm. The thickness of the third layer is not particularly limited, but for example, it is about 4 nm to 20 nm.

[0054] The configuration of the first electrode layer 51f1 is not limited to the examples described above. For example, either the second or third layer described above may be omitted, or a layer made of iridium may be further provided between the first and second layers. Alternatively, a layer made of an electrode material other than iridium and platinum may be used instead of, or in addition to, the second and third layers. Examples of such electrode materials include metallic materials such as aluminum (Al), nickel (Ni), gold (Au), and copper (Cu). One of these may be used alone, or two or more may be used in combination in the form of a laminate or alloy.

[0055] The piezoelectric layer 51f2 is positioned between the first electrode layer 51f1 and the second electrode layer 51f3. The piezoelectric layer 51f2 is a strip-shaped structure that extends along the Y-axis so as to be continuous across multiple piezoelectric elements 51f. The piezoelectric layer 51f2 may also be provided individually for each piezoelectric element 51f or for each active part P1, P2, and P3.

[0056] The piezoelectric layer 51f2 is composed of a piezoelectric material having a perovskite-type 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 zirconium magnesium niobate titanate (Pb(Zr,Ti)(Mg,Nb)O3). Among these, lead zirconate titanate is preferably used as the constituent material of the piezoelectric layer 51f2. The piezoelectric layer 51f2 may contain small amounts of other elements such as impurities. Furthermore, the piezoelectric material constituting the piezoelectric layer 51f2 may be a lead-free material such as barium titanate.

[0057] The piezoelectric layer 51f2 is formed by, for example, creating a piezoelectric precursor layer using a liquid-phase method such as the sol-gel method or the MOD (metal-organic decomposition) method, and then crystallizing the precursor layer by firing. Here, the piezoelectric layer 51f2 may consist of a single layer, but when it consists of multiple layers, there is an advantage in that the properties of the piezoelectric layer 51f2 can be easily improved even if the thickness of the piezoelectric layer 51f2 is increased.

[0058] The second electrode layer 51f3 is a strip-shaped common electrode that extends in the direction along the Y axis so as to be continuous across multiple piezoelectric elements 51f. An offset potential VBS is supplied to the second electrode layer 51f3 as a predetermined reference voltage.

[0059] The second electrode layer 51f3 has, for example, a layer composed of iridium (Ir) and a layer composed of titanium (Ti), which are stacked in this order in the Z1 direction. The second electrode layer 51f3 is formed by, for example, known film deposition techniques such as sputtering, and known processing techniques such as photolithography and etching.

[0060] Furthermore, the constituent material of the second electrode layer 51f3 is not limited to iridium and titanium, but may also be a metallic material such as platinum (Pt), aluminum (Al), nickel (Ni), gold (Au), or copper (Cu). The second electrode layer 51f3 may also be constructed using one of these metallic materials alone, or by combining two or more materials in the form of a laminate or alloy. The second electrode layer 51f3 may also be a single layer.

[0061] The piezoelectric element 51f described above has active parts P1, P2, and P3. Active part P1 is the portion of the piezoelectric element 51f where the individual electrodes 51f1a, the piezoelectric layer 51f2, and the second electrode layer 51f3 all overlap when viewed in the thickness direction of the diaphragm 51e. Active part P2 is the portion of the piezoelectric element 51f where the individual electrodes 51f1b, the piezoelectric layer 51f2, and the second electrode layer 51f3 all overlap when viewed in the thickness direction of the diaphragm 51e. Active part P3 is the portion of the piezoelectric element 51f where the individual electrodes 51f1c, the piezoelectric layer 51f2, and the second electrode layer 51f3 all overlap when viewed in the thickness direction of the diaphragm 51e.

[0062] The active part P1 is positioned between the active parts P2 and P3. In the example shown in Figure 6, the active parts P2, P1, and P3 are arranged in this order in the Y1 direction. Also, each of the active parts P1, P2, and P3 extends in the direction along the X axis.

[0063] Here, the active part P1, when viewed in the thickness direction of the diaphragm 51e, overlaps the center of the pressure chamber C and does not overlap the outer edge BD of the pressure chamber C. On the other hand, the active parts P2 and P3, when viewed in the thickness direction of the diaphragm 51e, overlap the pressure chamber C at a position closer to the outer edge BD of the pressure chamber C than the active part P1. In the example shown in Figure 6, the active parts P2 and P3, when viewed in the thickness direction of the diaphragm 51e, are positioned across the pressure chamber C and the partition wall 51b1 and overlap the outer edge BD.

[0064] The width W1 of the active part 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. Similarly, the width W2 of the active part P2 along the Y-axis is smaller than the width of the pressure chamber C along the Y-axis, preferably less than or equal to half the width of the pressure chamber C along the Y-axis. Likewise, the width W3 of the active part P3 along the Y-axis is smaller than the width of the pressure chamber C along the Y-axis, preferably less than or equal to half the width of the pressure chamber C along the Y-axis. Here, widths W2 and W3 may be equal to or different from each other.

[0065] 1-5. Configuration of the switching circuit Figure 7 is a diagram illustrating the switching circuit 52. The switching circuit 52 will be described below based on Figure 7.

[0066] As shown in Figure 7, the switching circuit 52 is connected to wiring LHa and wiring LHb, respectively. Wiring LHa is a signal line that transmits the first drive signal Com-A. Wiring LHb is a signal line that transmits the second drive signal Com-B. In addition, wiring LHd is connected to the second electrode layer 51f3 of the piezoelectric element 51f. Wiring LHd is a power supply line that supplies the offset potential VBS.

[0067] The switching circuit 52 includes a plurality of switches SWa and a plurality of switches SWb that correspond one-to-one with a plurality of piezoelectric elements 51f, and a connection state specifying circuit 52a that specifies the connection state of these switches.

[0068] Switch SWa is a switch that switches between conduction (on) and non-conduction (off) between the wiring LHa for the transmission of the first drive signal Com-A and the individual electrode 51f1a of the piezoelectric element 51f. Switch SWb is a switch that switches between conduction (on) and non-conduction (off) between the wiring LHa for the transmission of the second drive signal Com-B and the individual electrodes 51f1b and 51f1c of the piezoelectric element 51f. Each of these switches is, for example, a transmission gate.

[0069] The connection status specification circuit 52a generates a connection status specification signal SLa that specifies the on / off state of 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.

[0070] For example, although not shown in the diagram, the connection state designation circuit 52a has multiple transfer circuits, multiple latch circuits, and multiple decoders so as to correspond one-to-one with multiple piezoelectric elements 51f. Of these, the transfer circuits are supplied with a print data signal SI. Here, the print data signal SI includes an individual designation signal for each piezoelectric element 51f, and the individual designation signals are supplied serially, for example, and are transferred sequentially to multiple transfer circuits in synchronization with the clock signal CLK. The latch circuits latch the individual designation signals supplied to the transfer circuits based on the latch signal LAT. The decoders generate a connection state designation signal SLa based on the individual designation signals, the latch signal LAT, and the change signal CNG.

[0071] As described above, the on / off states of switches SWa and SWb are switched according to the connection state specification signal SLa that is generated. For example, switches SWa and SWb are turned on when the connection state specification signal SLa is at a high level and turned off when it is at a low level. As described above, the switching circuit 52 supplies a part or all of the waveform included in the first drive signal Com-A as a supply signal Vin-A to one or more piezoelectric elements 51f selected from the plurality of piezoelectric elements 51f, and supplies a part or all of the waveform included in the second drive signal Com-B as a supply signal Vin-B.

[0072] 1-6. First drive signal and second drive signal Figure 8 is a diagram illustrating 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 Figure 8 represents 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 Figure 8 represents 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 Figure 8 may also represent the potential of the first drive signal Com-A, and the vertical axis "Voltage" in the lower part of Figure 8 may also represent the potential of the second drive signal Com-B.

[0073] As shown in Figure 8, the first drive signal Com-A and the second drive signal Com-B each have waveforms that change with a predetermined unit period Tu. The unit period Tu is defined by the latch signal LAT mentioned above, and corresponds to the printing period in which ink dots from the nozzle N are formed on the medium M.

[0074] In the example shown in Figure 8, the first drive signal Com-A has a waveform that returns to the intermediate potential Vca via potential VHa within a unit period Tu, with the intermediate potential Vca as the reference potential. Here, the intermediate potential Vca is an example of the "first potential" and the "fifth potential," and is, for example, a potential below the offset potential VBS. Potential VHa is an example of the "second potential," and is a potential higher than the offset potential VBS and also higher than the intermediate potential Vca.

[0075] Here, the potential of the first drive signal Com-A is maintained at the intermediate potential Vca over period P1a, then rises from the intermediate potential Vca to potential VHa over period P2a, is maintained at potential VHa over period P3a, then falls from potential VHa to the intermediate potential Vca over period P4a, and is maintained at the intermediate potential Vca over period P5a. Period P2a is an example of the "first period". Period P3a is an example of the "first holding period". Period P4a is an example of the "third period". Note that periods P1a, P2a, P3a, P4a, and P5a are included in this order from the start to the end of the unit period Tu.

[0076] The waveform portion of the first drive signal Com-A during period P2a represents the contraction element ESa, which 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 represents the holding element ERa, which is an example of a "first holding element". The waveform portion of the first drive signal Com-A during period P4a represents the expansion element EEa, which expands the volume of the pressure chamber C.

[0077] On the other hand, the second drive signal Com-B has a waveform that returns to the intermediate potential Vcb via potential VHb within a unit period Tu, with the intermediate potential Vcb as the reference potential. Here, the intermediate potential Vcb is an example of the "third potential" and the "sixth potential," and is, for example, a potential below the offset potential VBS. 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.

[0078] Here, the potential of the second drive signal Com-B is maintained at the intermediate potential Vcb over period P1b, then rises from the intermediate potential Vcb to potential VHb over period P2b, is maintained at potential VHb over period P3b, then falls from potential VHb to the intermediate potential Vcb over period P4b, and is maintained at the intermediate potential Vcb over period P5b. Period P4b is an example of a "second period". Period P3b is an example of a "second holding period". Period P2b is an example of a "fourth period". Note that periods P1b, P2b, P3b, P4b, and P5b are included in this order from the start to the end of the unit period Tu.

[0079] The waveform portion of the second drive signal Com-B during period P2b represents the expansion element EEb, which expands the volume of the pressure chamber C. The waveform portion of the second drive signal Com-B during period P3b represents the holding element ERb, which is an example of a "second holding element". The waveform portion of the second drive signal Com-B during period P4b represents the contraction element ESb, which contracts the volume of the pressure chamber C. The contraction element ESb is an example of a "second contraction element".

[0080] In this embodiment, the first drive signal Com-A and the second drive signal Com-B have substantially identical waveforms. However, the phases at which the waveforms of the first drive signal Com-A and the second drive signal Com-B are supplied are different. "Substantially identical waveforms" means that the patterns match when waveforms due to electrical noise and errors are removed.

[0081] In other words, the length of the period P1a of the first drive signal Com-A is longer than the length of the period P1b of the second drive signal Com-B. The length of the period P2a of the first drive signal Com-A and the length of the period P2b of the second drive signal Com-B are equal. The length of the period P3a of the first drive signal Com-A and the length of the period P3b of the second drive signal Com-B are equal. The length of the period P4a of the first drive signal Com-A and the length of the period P4b of the second drive signal Com-B are equal. The length of the period P5a of the first drive signal Com-A is shorter than the length of the period P5b of the second drive signal Com-B.

[0082] Note that 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 only need to generate a single waveform and supply it with a phase shift. Therefore, compared to the case where the waveforms of the first drive signal Com-A and the second drive signal Com-B are different, there is an advantage in that the configuration of the drive signal generation circuit 24 can be simplified.

[0083] The start timing of period P3a of the first drive signal Com-A is later than the end timing of period P3b of the second drive signal Com-B.

[0084] 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.

[0085] In the example shown in Figure 8, within the unit period Tu, the start time of period P2a is later than the start time of period P4b. Consequently, within the unit period Tu, the end time of period P2a is later than the end time of period P4b.

[0086] 1-7. Shrinkage process Figure 9 is a diagram illustrating the shrinkage process SS in the first embodiment. In Figure 9, the first drive signal Com-A is shown by a solid line, and the second drive signal Com-B is shown by a dashed line. In the example shown in Figure 9, the potentials VHa and VHb are equal to each other, and the intermediate potentials Vca and Vcb are equal to each other.

[0087] Furthermore, 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 the case where they are not equal.

[0088] As described above, after the supply of the holding element ERb for the second drive signal Com-B to the active parts P2 and P3 is completed, the supply of the holding element ERa for the first drive signal Com-A to the active part P1 is started after a period PS. During this period PS, the contraction process SS is performed.

[0089] Figure 10 is a schematic diagram illustrating the deformation of the diaphragm 51e due to the first drive signal Com-A. Figure 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 explanation, the piezoelectric element 51F is not shown, and the diaphragm 51e is shown schematically. In Figures 10 and 11, the diaphragm 51e in its natural state, which is the reference state, is shown by a dashed line. 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.

[0090] When a voltage is applied to the active parts P1, P2, and P3 in the direction along the Z-axis, they tend to contract in the direction perpendicular to the Z-axis as they expand in the direction along the Z-axis. At this time, since the faces of the active parts P1, P2, and P3 facing the Z2 direction are fixed to the diaphragm 51e, the amount of contraction of the faces of the active parts P1, P2, and P3 facing the Z2 direction is smaller than the amount of contraction of the faces of the active parts P1, P2, and P3 facing the Z1 direction. As a result, the active parts P1, P2, and P3 deform by bending in the direction along the Z-axis, and the diaphragm 51e deforms accordingly.

[0091] Here, of the two ends of the active parts P2 and P3 along the Y-axis, the end closer to the partition wall 511 of the pressure chamber C is restricted in displacement by the partition wall 511, while the end further away from the partition wall 511 of the pressure chamber C is less restricted in displacement. Therefore, when the active parts P2 and P3 attempt to contract along the Y-axis, the far end is displaced in the Z1 direction. As a result, the diaphragm 51e deforms so that the first surface F1 becomes concave. Consequently, when the holding element ERb of the second drive signal Com-B is supplied to the active parts P2 and P3, the diaphragm 51e deforms so that the first surface F1 becomes concave, as shown in Figure 10. This causes the volume of the pressure chamber C to expand.

[0092] On the other hand, both ends of the active part P1 in the direction along the Y axis are located relatively far from the partition wall 511 of the pressure chamber C, and are not easily restricted in displacement by the partition wall 511. Therefore, when the active part P1 attempts to contract in the direction along the Y axis, the diaphragm 51e deforms so that the first surface F1 becomes convex. Consequently, when the holding element ERa of the first drive signal Com-A is supplied to the active part P1, the diaphragm 51e deforms so that the first surface F1 becomes convex, as shown in Figure 11. As a result, the volume of the pressure chamber C contracts.

[0093] Here, during the period in which the active units P2 and P3 receive the contraction element ESb of the second drive signal Com-B, they attempt to return the diaphragm 51e from the state shown by the solid line in Figure 10 to the state shown by the dashed line. Also, during the period in which the active unit P1 receives the contraction element ESa of the first drive signal Com-A, it attempts to deform the diaphragm 51e from the state shown by the dashed line in Figure 11 to the state shown by the solid line.

[0094] In the contraction process SS, when deforming the diaphragm 51e from the state shown by the dashed line in Figure 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 Figure 10 to the state shown by the dashed line can be utilized. That is, in the contraction process SS, when the active unit P1 deforms the diaphragm 51e from the reference state to a state that contracts the volume of the pressure chamber C, the forces that attempt to return the diaphragm 51e from the state in which the volume of the pressure chamber C has expanded can be utilized. Therefore, the amount of deformation of the diaphragm 51e can be increased compared to a configuration in which only the active unit P1 is driven by the first drive signal Com-A. As a result, ink can be ejected efficiently from the nozzle N.

[0095] In contrast, if the start timing of the supply of the contraction element ESa of the first drive signal Com-A to the active unit P1 coincides with or is after the end timing of the supply to the active units P2 and P3, when deforming the diaphragm 51e from the state shown by the dashed line in Figure 11 to the state shown by the solid line, it is not possible to utilize the force that attempts to return the diaphragm 51e from the state shown by the solid line in Figure 10 to the state shown by the dashed line, and the aforementioned effect cannot be obtained.

[0096] As described above, the liquid discharge device 100 comprises a diaphragm 51e, a pressure chamber substrate 51b, a piezoelectric element 51f, and a drive signal generation circuit 24, which is an example of a "drive signal generation unit". Here, as previously mentioned, 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 demarcates a pressure chamber C that communicates with a nozzle N for discharging ink, which is an example of a "liquid". The piezoelectric element 51f is laminated on the second surface F2 and has an active part P1, which is an example of a "first active part", and an active part P2, which is an example of a "second active part". The active part P1 overlaps the center of the pressure chamber C when viewed in the thickness direction of the diaphragm 51e. The active part P2 overlaps the pressure chamber C at a position closer to the outer edge of the pressure chamber C than the active part P1 when viewed in the thickness direction of the diaphragm 51e. The drive signal generation circuit 24 generates a first drive signal Com-A for driving the active unit P1 and a second drive signal Com-B for driving the active unit P2.

[0097] The first drive signal Com-A includes a contraction element ESa, which is an example of a "first contraction element," for each periodic unit period Tu. On the other hand, the second drive signal Com-B includes a contraction element ESb, which is an example of a "second contraction element," for each unit period Tu. Each of the contraction elements ESa and ESb reduces the volume of the pressure chamber C. The liquid discharge device 100 then performs a contraction process SS. The contraction process SS is a period in which a period P2a, which is an example of a "first period," and a period P4b, which is an example of a "second period," overlap. During period P2a, the contraction element ESa is supplied to the active unit P1. During period P4b, the contraction element ESb is supplied to the active unit P2.

[0098] Here, period P2a is the period during which, for each unit period Tu, the potential changes from an intermediate potential Vca, which is an example of the "first potential," to a potential VHa, which is an example of the "second potential." Similarly, period P4b is the period during which, for each unit period Tu, the potential changes from an intermediate potential Vcb, which is an example of the "third potential," to a potential VHb, which is an example of the "fourth potential."

[0099] In the liquid dispensing device 100 described above, periods P2a and P4b overlap during the shrinkage process SS. Compared to a configuration where these periods do not overlap, this allows for a larger displacement of the diaphragm 51e and a faster displacement speed of the diaphragm 51e. As a result, the ink discharge speed from the nozzle N can be increased, and the amount of ink discharged per nozzle N can be increased. Furthermore, by increasing the displacement speed of the diaphragm 51e, the ink discharge cycle from the nozzle N can also be shortened. In this way, the discharge characteristics of the liquid dispensing device 100 can be improved.

[0100] As mentioned above, during the contraction process SS, the relative magnitudes of the potentials of the first drive signal Com-A and the second drive signal Com-B are reversed. That is, during the period when periods P2a and P4b overlap, the relative magnitudes of the voltages of the first drive signal Com-A and the second drive signal Com-B are reversed.

[0101] Furthermore, as mentioned above, in a unit period Tu, the start timing of the contraction element ESa is later than the start timing of the contraction element ESb. That is, in a unit period Tu, the start timing of period P2a is later than the start timing of period P4b. Therefore, excessive stress is prevented between the part of the diaphragm 51e deformed by the active part P1 and the part of the diaphragm 51e deformed by the active part P2. As a result, damage such as cracks in the diaphragm 51e can be reduced.

[0102] Furthermore, as mentioned above, in a unit period Tu, the termination timing of the contraction element ESa is later than the termination timing of the contraction element ESb. Therefore, in a unit period Tu, the start timing of the contraction element ESa can be set later than the start timing of the contraction element ESb.

[0103] Furthermore, as mentioned above, the piezoelectric element 51f further has an active part P3, which is an example of a "third active part". The active part P3 overlaps the pressure chamber C at a position closer to the outer edge of the pressure chamber C than the active part P1 when viewed in the thickness direction of the diaphragm 51e. The active part P1 is located between the active parts P2 and P3 when viewed in the thickness direction of the diaphragm 51e. Therefore, the active part P3 can be made to function in the same way as the active part P2.

[0104] Furthermore, as described above, the piezoelectric element 51f has a first electrode layer 51f1, a piezoelectric layer 51f2, and a second electrode layer 51f3 in that order, moving away from the diaphragm 51e. The piezoelectric layer 51f2 and the second electrode layer 51f3 are provided in common across the active parts P1, P2, and P3. In contrast, the first electrode layer 51f1 includes a plurality of individual electrodes 51f1a, 51f1b, and 51f1c, which are individually provided in the active parts P1, P2, and P3. Therefore, compared to a configuration in which individual electrodes are provided for each active part in the second electrode layer 51f3, the wiring can be simplified. Also, compared to a configuration in which the piezoelectric layer 51f2 is divided for each active part, the manufacturing of the piezoelectric layer 51f2 can be simplified.

[0105] 2. Second Embodiment The following describes a second embodiment of this disclosure. The following description will focus on the differences from the first embodiment.

[0106] Figure 12 is a diagram illustrating the shrinkage process SS in the second embodiment. This embodiment is the same as the first embodiment described above, except that, as shown in Figure 12, the intermediate potential Vcb of the second drive signal Com-B is higher than the intermediate potential Vca of the first drive signal Com-A.

[0107] The second embodiment described above also improves the discharge characteristics of the liquid discharge device 100. In this embodiment, as mentioned above, the intermediate potential Vcb is higher than the intermediate potential Vca. Therefore, by appropriately setting the difference between these potentials, the hardness of the diaphragm 51e can be adjusted. As a result, even if there are manufacturing variations, the discharge characteristics among multiple head tips 51 can be standardized.

[0108] 3. Third Embodiment The following describes a third embodiment of this disclosure. The differences from the first embodiment will be the main focus of this description.

[0109] Figure 13 is a diagram illustrating the first drive signal Com-A and the second drive signal Com-B in the third embodiment. In the example shown in Figure 13, the first drive signal Com-A has a waveform that, with the intermediate potential Vca as the reference potential, returns to the intermediate potential Vca within a unit period Tu, passing through potential VLa and potential VHa in that order. Potential VLa is a lower potential than the intermediate potential Vca.

[0110] Here, the potential of the first drive signal Com-A is maintained at the intermediate potential Vca over period P1c, then decreases from the intermediate potential Vca to potential VLa over period P2c, maintained at potential VLa over period P3c, then increases from potential VLa to potential VHa over period P4c, maintained at potential VHa over period P5c, then decreases from potential VHa to the intermediate potential Vca over period P6c, and maintained at the intermediate potential Vca over period P7c. Period P2c is an example of the "third period". Period P4c is an example of the "first period". Note that periods P1c, P2c, P3c, P4c, P5c, P6c, and P7c are included in this order from the start to the end of the unit period Tu.

[0111] The waveform portion of the first drive signal Com-A during period P2c represents the expansion element EEa1, which expands the volume of the pressure chamber C. The expansion element EEa1 is an example of a "first expansion element". The waveform portion of the first drive signal Com-A during period P3c represents the holding element ERa1. The waveform portion of the first drive signal Com-A during period P4c represents the contraction element ESa, which 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 P5c represents the holding element ERa2. The waveform portion of the first drive signal Com-A during period P6c represents the expansion element EEa2, which expands the volume of the pressure chamber C.

[0112] On the other hand, the second drive signal Com-B shown in Figure 13 has a waveform that, with the intermediate potential Vcb as the reference potential, returns to the intermediate potential Vcb within a unit period Tu, passing through potential VLb and potential VHb in that order. Potential VLb is lower than the intermediate potential Vcb.

[0113] Here, the potential of the second drive signal Com-B is maintained at the intermediate potential Vcb over period P1d, then decreases from the intermediate potential Vcb to potential VLb over period P2d, maintained at potential VLb over period P3d, then increases from potential VLb to potential VHb over period P4d, maintained at potential VHb over period P5d, then decreases from potential VHb to the intermediate potential Vcb over period P6d, and maintained at the intermediate potential Vcb over period P7d. Period P4d is an example of the "fourth period". Period P6d is an example of the "second period". Note that periods P1d, P2d, P3d, P4d, P5d, P6d, and P7d are included in this order from the start to the end of the unit period Tu.

[0114] The waveform portion of the second drive signal Com-B during period P2d represents the contraction element ESb1, which contracts the volume of pressure chamber C. The waveform portion of the second drive signal Com-B during period P3d represents the holding element ERb1. The waveform portion of the second drive signal Com-B during period P4d represents the expansion element EEb, which expands the volume of pressure chamber C. The expansion element EEb is an example of a "second expansion element". The waveform portion of the second drive signal Com-B during period P5d represents the holding element ERb2. The waveform portion of the second drive signal Com-B during period P6d represents the contraction element ESb2, which contracts the volume of pressure chamber C. The contraction element ESb2 is an example of a "second contraction element".

[0115] 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 respect to each other.

[0116] Here, the length of the period P1c of the first drive signal Com-A is longer than the length of the period P1d of the second drive signal Com-B. The length of the period P2c of the first drive signal Com-A and the length of the period P2d of the second drive signal Com-B are equal. The length of the period P3c of the first drive signal Com-A and the length of the period P3d of the second drive signal Com-B are equal. The length of the period P4c of the first drive signal Com-A and the length of the period P4d of the second drive signal Com-B are equal. The length of the period P5c of the first drive signal Com-A and the length of the period P5d of the second drive signal Com-B are equal. The length of the period P6c of the first drive signal Com-A and the length of the period P6d of the second drive signal Com-B are equal. The length of the period P7c of the first drive signal Com-A is shorter than the length of the period P7d of the second drive signal Com-B.

[0117] Note that 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 identical, the drive signal generation circuit 24 may only need 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 the case where the waveforms of the first drive signal Com-A and the second drive signal Com-B are different.

[0118] The start timing of period P3c of the first drive signal Com-A is later than the end timing of period P3d of the second drive signal Com-B. Similarly, the start timing of period P5c of the first drive signal Com-A is later than the end timing of period P5d of the second drive signal Com-B.

[0119] Here, at least a portion of the period P2c of the first drive signal Com-A and at least a portion of the period P4d of the second drive signal Com-B overlap each other in time during period PE.

[0120] In the example shown in Figure 13, within the unit period Tu, the start time of period P2c is before the start time of period P4d. Also, within the unit period Tu, the end time of period P2c is before the end time of period P4d. Note that within the unit period Tu, the start time of period P2c may be after the start time of period P4d, and the end time of period P2c may be after the end time of period P4d.

[0121] Furthermore, at least a portion of the period P4c of the first drive signal Com-A and at least a portion of the period P6d of the second drive signal Com-B overlap each other in time during the period PS.

[0122] In the example shown in Figure 13, within the unit period Tu, the start time of period P4c is before the start time of period P6d. Also, within the unit period Tu, the end time of period P2c is before the end time of period P4d. Note that within the unit period Tu, the start time of period P4c may be after the start time of period P6d, and the end time of period P2c may be after the end time of period P4d.

[0123] Figure 14 is a diagram illustrating the contraction process SS and expansion process SE in the third embodiment. In Figure 14, the first drive signal Com-A is shown by a solid line, and the second drive signal Com-B is shown by a dashed line. In the example shown in Figure 14, potentials VLa and VLb are equal to each other, potentials VHa and VHb are equal to each other, and intermediate potentials Vca and Vcb are equal to each other.

[0124] Furthermore, the potentials VLa and VLb may be different from each other, 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 VLa and VLb are equal to each other, 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 the cases where they are not equal.

[0125] As described above, after the supply of the holding element ERb1 of the second drive signal Com-B to the active parts P2 and P3 is completed, the supply of the holding element ERa1 of the first drive signal Com-A to the active part P1 is started after a period PE. During this period PE, the expansion process SE is executed. The contraction process SS is the same as in the first embodiment described above.

[0126] During the period when the holding element ERb1 of the second drive signal Com-B is supplied to the active parts P2 and P3, the diaphragm 51e deforms so that the first surface F1 becomes convex. As a result, the volume of the pressure chamber C is reduced. On the other hand, during the period when the holding element ERa1 of the first drive signal Com-A is supplied to the active part P1, the diaphragm 51e deforms so that the first surface F1 becomes concave. As a result, the volume of the pressure chamber C is expanded.

[0127] As mentioned above, in the expansion process SE, in which the volume of the pressure chamber C changes from a contracted state to an expanded state, when the active unit P1 deforms the diaphragm 51e from the reference state to a state that expands the volume of the pressure chamber C, the force of the active units P2 and P3 that tries to return the diaphragm 51e from the contracted state to the reference state can be utilized. For this reason, the amount of deformation of the diaphragm 51e can be increased compared to a configuration in which only the active unit P1 is driven by the first drive signal Com-A. As a result, ink can be ejected from the nozzle N efficiently.

[0128] The discharge characteristics of the liquid discharge device 100 can also be improved by the third embodiment described above. In this embodiment, as mentioned above, the first drive signal Com-A includes an expansion element EEa1, which is an example of a "first expansion element". The second drive signal Com-B includes an expansion element EEb, which is an example of a "second expansion element". Each of the expansion elements EEa1 and EEb expands the volume of the pressure chamber C for each unit period Tu. The liquid discharge device 100 then performs an expansion process SE. The expansion process SE is a period in which a period P2c, which is an example of a "third period", and a period P4d, which is an example of a "fourth period", overlap. During period P2c, the expansion element EEa1 is supplied to the active unit P1. During period P4d, the expansion element EEb is supplied to the active units P2 and P3.

[0129] In the expansion process SE, periods P2c and P4d overlap, allowing for an increase in the force of the ink introduced into the pressure chamber C compared to a configuration where these periods do not overlap. Furthermore, the ink ejection cycle from the nozzle N can be shortened compared to a configuration where these periods do not overlap.

[0130] As mentioned above, in a unit period Tu, the expansion process SE is executed before the contraction process SS. Therefore, the amount discharged per discharge from the nozzle N can be increased.

[0131] Furthermore, as mentioned above, periods P4c and P4d do not overlap, and periods P2c and P6d do not overlap. Therefore, excessive stress is prevented between the portion of the diaphragm 51e deformed by the active part P1 and the portion of the diaphragm 51e deformed by the active part P2. As a result, damage such as cracks to the diaphragm 51e can be reduced.

[0132] 4. Fourth Embodiment The following describes a fourth embodiment of this disclosure. The following description will focus on the differences from the first embodiment.

[0133] Figure 15 is a diagram illustrating the contraction process SS and expansion process SE in the fourth embodiment. This embodiment is the same as the third embodiment described above, except that the contraction element ESb1 and the holding element ERb1 of the second drive signal Com-B are omitted. Therefore, the second drive signal Com-B in this embodiment is the same as the second drive signal Com-B in the first embodiment.

[0134] The fourth embodiment described above can also improve the discharge characteristics of the liquid dispensing device 100.

[0135] 5. Fifth Embodiment The fifth embodiment of this disclosure will be described below. The differences from the first embodiment will be the main focus of this description.

[0136] Figure 16 is a diagram illustrating the contraction process SS, expansion process SE, and vibration damping process SC in the fifth embodiment. This embodiment is the same as the third embodiment described above, except that the phases of the first drive signal Com-A and the second drive signal Com-B are different.

[0137] In this embodiment, the contraction process SS is executed when the period of the contraction element ESa of the first drive signal Com-A and the period of the contraction element ESb1 of the second drive signal Com-B overlap for period PS. Furthermore, the expansion process SE is executed when the period of the expansion element EEa2 of the first drive signal Com-A and the period of the expansion element EEb of the second drive signal Com-B overlap for period PE. After the expansion process SE, the damping process SC is executed by applying a damping force to the diaphragm 51e using the holding element ERb2 of the second drive signal Com-B. It is preferable that the timing of the damping process SC and the potential VHb of the damping process SC be appropriately determined according to the vibration period and amplitude of the diaphragm 51e generated by the processes prior to the expansion process SE.

[0138] The fifth embodiment described above also improves the discharge characteristics of the liquid discharge device 100. In this embodiment, as mentioned above, in a unit period Tu, the expansion process SE is executed after the contraction process SS. Therefore, ink can be supplied to the pressure chamber C, where the ink has decreased due to the execution of the contraction process SS, by executing the expansion process SE. In addition, after the active part P1 is driven by the first drive signal Com-A, the vibration damping process SC is executed to dampen the vibration of the diaphragm 51e. As a result, the discharge cycle can be shortened while improving print quality.

[0139] 6. Sixth Embodiment The sixth embodiment of this disclosure will be described below. The following description will focus on the differences from the first embodiment.

[0140] Figure 17 is a diagram illustrating the first drive signal Com-A and the second drive signal Com-B in the sixth embodiment. In the example shown in Figure 17, the first drive signal Com-A is the same as the first drive signal COM-A in the first embodiment.

[0141] On the other hand, the second drive signal Com-B shown in Figure 17 is a signal with the opposite phase to the first drive signal Com-A. That is, the second drive signal Com-B shown in Figure 17 has a waveform that returns to the intermediate potential Vcb via potential VLb within a unit period Tu, with the intermediate potential Vcb as the reference potential. The intermediate potential Vcb is an example of the "third potential" and the "sixth potential". Potential VLb is an example of the "fourth potential".

[0142] Here, the potential of the second drive signal Com-B is maintained at the intermediate potential Vcb over period P1b, then decreases from the intermediate potential Vcb to the potential VLb over period P2b, maintained at the potential VLb over period P3b, then increases from the potential VLb to the intermediate potential Vcb over period P4b, and maintained at the intermediate potential Vcb over period P5b. Period P2b is an example of the "second period". Period P4b is an example of the "fourth period".

[0143] The waveform portion of the second drive signal Com-B during period P2b is an example of a "second contraction element," which is the contraction element ESb that contracts the volume of the pressure chamber C. The waveform portion of the second drive signal Com-B during period P3b is an example of a "second holding element," which is the holding element ERb. The waveform portion of the second drive signal Com-B during period P4b is an example of a "second expansion element," which is the expansion element EEb that expands the volume of the pressure chamber C.

[0144] Here, at least a portion of the period P2a of the first drive signal Com-A and at least a portion of the period P2b of the second drive signal Com-B overlap in time during period PS. Also, at least a portion of the period P4a of the first drive signal Com-A and at least a portion of the period P4b of the second drive signal Com-B overlap in time during period PE. By providing such periods PS and PE, it becomes possible to improve the discharge characteristics, as in other embodiments.

[0145] In the example shown in Figure 17, the lengths of periods P1a and P1b are equal. The lengths of periods P2a and P2b are equal. The lengths of periods P3a and P3b are equal. The lengths of periods P4a and P4b are equal. The lengths of periods P5a and P5b are equal. When the waveforms of the first drive signal Com-A and the second drive signal Com-B are out of phase with 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 out of phase.

[0146] In the example shown in Figure 17, the lengths of periods P3a and P3b are the same, but these lengths may be different. That is, the length of period P3a may be longer or shorter than the length of period P3b. In this case, even if an error occurs in the phase of the first drive signal Com-A and the second drive signal Com-B for some reason, there is an advantage in that fluctuations in the discharge characteristics can be easily reduced.

[0147] Figure 18 is a diagram illustrating the contraction process SS and expansion process SE in the sixth embodiment. In Figure 18, the first drive signal Com-A is shown by a solid line, and the second drive signal Com-B is shown by a dashed line. In the example shown in Figure 18, the potentials VHa and Vcb are equal to each other, and the intermediate potentials Vca and VLb are equal to each other.

[0148] Furthermore, the potentials VHa and Vcb may be different from each other, and the intermediate potential Vca and VLb may be different from each other. However, when the potentials VHa and Vcb are equal to each other, and the intermediate potential Vca and VLb 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 the case where they are not equal.

[0149] During period PS, the shrinkage process SS is performed. Subsequently, during period PE, the expansion process SE is performed.

[0150] The sixth embodiment described above, like the first embodiment described above, can improve the discharge characteristics of the liquid discharge device 100. In this embodiment, as described above, the first drive signal Com-A includes a period P3a during which the voltage is held after the contraction element ESa as an example of the "first holding period". On the other hand, the second drive signal Com-B includes a period P3b during which the voltage is held after the contraction element ESb as an example of the "second holding period". Here, if the lengths of periods P3a and P3b are different, even if there is some error in the phase of the first drive signal Com-A and the second drive signal Com-B, the length of the overlapping period between periods P3a and P3b is less likely to fluctuate. Therefore, it is possible to reduce the variation in the amount of ink discharged from the nozzle N due to this error. In contrast, if the lengths of periods P3a and P3b are equal, the length of the overlapping period between periods P3a and P3b is more likely to fluctuate due to this error. Therefore, variations in the amount of ink discharged from the nozzle N are more likely to occur. However, in this case, there is the advantage that the drive signal generation circuit 24 can be simplified.

[0151] Furthermore, as mentioned above, the first drive signal Com-A and the second drive signal Com-B are signals with opposite phases to each other. Therefore, the influence of electrical noise between two adjacent output elements (electronic crosstalk) can be reduced. Also, in this case, since each element included in the first drive signal Com-A and the second drive signal Com-B is executed simultaneously, the overall time required for a unit period Tu can be shortened compared to the first to fifth embodiments, etc.

[0152] Furthermore, as mentioned above, the intermediate potential Vcb is higher than the intermediate potential Vca. Therefore, in the standby state when no ink is ejected from the nozzle N, the second drive signal Com-B maintains a state in which the volume of the pressure chamber C is expanded. As a result, tension is applied to the diaphragm 51e, which can increase the spring constant of the diaphragm 51e. Consequently, by shortening the natural vibration period of the diaphragm 51e, the ink ejection period from the nozzle N can be shortened.

[0153] As mentioned above, the first drive signal Com-A includes, for each unit period Tu, a period P3a, which is an example of a "first holding period," and a period P4a, which is an example of a "third period." Period P3a follows period P2a, which is an example of a "first period," and holds the potential VHa, which is an example of a "second potential." Period P4a follows period P3a and changes from the potential VHa to the intermediate potential Vca, which is an example of a "fifth potential." On the other hand, the second drive signal Com-B includes, for each unit period Tu, a period P3b, which is an example of a "second holding period," and a period P4b, which is an example of a "fourth period." Period P3b follows period P2b, which is an example of a "second period," and holds the potential VLb, which is an example of a "fourth potential." Period P4b follows period P3b and changes from the potential VLb to the intermediate potential Vcb, which is an example of a "sixth potential." Then, periods P4a and P4b overlap with each other. In other words, the expansion process SE is performed. This allows the force of the ink introduced into the pressure chamber C to be increased. It also allows the ink ejection cycle from the nozzle N to be shortened.

[0154] Here, as mentioned above, during period PE, when periods P4a and P4b overlap, the relative magnitudes of the potentials of the first drive signal Com-A and the second drive signal Com-B are reversed.

[0155] 7. Seventh Embodiment The following describes a seventh embodiment of this disclosure. The following description will focus on the differences from the first embodiment.

[0156] Figure 19 is a diagram illustrating the contraction and expansion processes in the seventh embodiment. This embodiment is the same as the sixth embodiment described above, except that, as shown in Figure 19, the intermediate potential Vcb of the second drive signal Com-B is different from the potential VHa of the first drive signal Com-A.

[0157] The seventh embodiment described above also improves the discharge characteristics of the liquid discharge device 100. In this embodiment, as mentioned above, the intermediate potential Vcb is different from the potential VHa. Therefore, by appropriately setting the intermediate potential Vcb, the stiffness of the diaphragm 51e can be adjusted. As a result, even if there are manufacturing variations, the discharge characteristics between multiple head tips 51 and between multiple pressure chambers C can be standardized.

[0158] 8. Eighth Embodiment The following describes an eighth embodiment of this disclosure. The following description will focus on the differences from the first embodiment.

[0159] Figure 20 is a diagram illustrating the first and second drive signals in the eighth embodiment. In the example shown in Figure 20, the first drive signal Com-A is the same as the first drive signal COM-A in the sixth embodiment.

[0160] On the other hand, the second drive signal Com-B shown in Figure 20 is a signal with the opposite phase to the first drive signal Com-A. That is, the second drive signal Com-B shown in Figure 20 has a waveform that, with the intermediate potential Vcb as the reference potential, returns to the intermediate potential Vcb within a unit period Tu, passing through potential VHb and potential VLb in that order.

[0161] Here, the potential of the second drive signal Com-B is maintained at the intermediate potential Vcb over period P1d, then rises from the intermediate potential Vcb to potential VHb over period P2d, is maintained at potential VHb over period P3d, then falls from potential VHb to potential VLb over period P4d, is maintained at potential VLb over period P5d, then rises from potential VLb to intermediate potential Vcb over period P6d, and is maintained at the intermediate potential Vcb over period P7d. Period P4d is an example of the "second period". Period P6d is an example of the "fourth period".

[0162] The waveform portion of the second drive signal Com-B during period P2d is an example of a "second expansion element," which is the expansion element EEb1 that expands the volume of the pressure chamber C. The waveform portion of the second drive signal Com-B during period P3d is an example of a "second holding element," which is the holding element ERb1. The waveform portion of the second drive signal Com-B during period P4d is an example of a "second contraction element," which is the contraction element ESb that contracts the volume of the pressure chamber C. The waveform portion of the second drive signal Com-B during period P5d is an example of a "second holding element," which is the holding element ERb2. The waveform portion of the second drive signal Com-B during period P6d is an example of a "second expansion element," which is the expansion element EEb2 that expands the volume of the pressure chamber C.

[0163] In this embodiment, the waveform portion of the first drive signal Com-A during period P2c is an example of a "first expansion element," which is the expansion element EEa1 that expands the volume of the pressure chamber C. The waveform portion of the first drive signal Com-A during period P3c is the holding element ERa1, which is an example of a "first holding element." The waveform portion of the first drive signal Com-A during period P4c is an example of a "first contraction element," which is the contraction element ESa that contracts the volume of the pressure chamber C. The waveform portion of the first drive signal Com-A during period P5c is the holding element ERa2, which is an example of a "first holding element." The waveform portion of the first drive signal Com-A during period P6c is an example of a "first expansion element," which is the expansion element EEa2 that expands the volume of the pressure chamber C.

[0164] Here, at least a portion of the period P2c of the first drive signal Com-A and at least a portion of the period P2d of the second drive signal Com-B overlap in time during period PE1. Also, at least a portion of the period P4c of the first drive signal Com-A and at least a portion of the period P4d of the second drive signal Com-B overlap in time during period PS. Furthermore, at least a portion of the period P6c of the first drive signal Com-A and at least a portion of the period P6d of the second drive signal Com-B overlap in time during period PE2.

[0165] Figure 21 is a diagram illustrating the contraction process SS, the first expansion process SE1, and the second expansion process SE2 in the eighth embodiment. In Figure 21, the first drive signal Com-A is shown by a solid line, and the second drive signal Com-B is shown by a dashed line. In the example shown in Figure 21, potentials VHa and VHb are equal to each other, and potentials VLa and VLb are equal to each other. Also, the intermediate potential Vcb is higher than the intermediate potential Vca.

[0166] Furthermore, the potentials VHa and VHb may be different from each other, and the potentials VLa and VLb may be different from each other.

[0167] During period PE1, the first expansion process SE1 is executed. Subsequently, during period PS, the contraction process SS is executed. Then, during period PE2, the second expansion process SE2 is executed. Both the first expansion process SE1 and the second expansion process SE2 have the same effect as the aforementioned expansion process SE. In other words, the first expansion process SE1 and the second expansion process SE2 can be said to be included in the expansion process SE.

[0168] The eighth embodiment described above also improves the discharge characteristics of the liquid discharge device 100. In this embodiment, as mentioned above, the expansion process SE includes a first expansion process SE1 and a second expansion process SE2. In a unit period Tu, the contraction process SS is performed between the first expansion process SE1 and the second expansion process SE2. Therefore, as with the other embodiments, the amount of ink discharged per cycle from the nozzle N can be increased. In addition, since each element included in the first drive signal Com-A and the second drive signal Com-B is executed simultaneously, the time required for a unit period Tu can be shortened overall compared to the first to fifth embodiments. In other words, it is possible to achieve both an increased discharge volume and a shorter liquid discharge cycle from the nozzle N.

[0169] 9. Ninth Embodiment The ninth embodiment of this disclosure will be described below. The differences from the first embodiment will be described in particular.

[0170] Figure 22 is a diagram illustrating the contraction process SS, the first expansion process SE1, and the second expansion process SE2 in the ninth embodiment. This embodiment is the same as the eighth embodiment described above, except that the potential difference between the intermediate potential Vca and the intermediate potential Vcb is different.

[0171] In this embodiment, the potential difference between the intermediate potential Vca and the intermediate potential Vcb is smaller than in the eighth embodiment. In the example shown in Figure 22, although the intermediate potential Vcb is slightly higher than the intermediate potential Vca, the potential difference between the intermediate potential Vca and the intermediate potential Vcb is extremely small. Note that the intermediate potentials Vca and Vcb may be equal to each other, or the intermediate potential Vcb may be lower than the intermediate potential Vca.

[0172] The ninth embodiment described above can also improve the discharge characteristics of the liquid dispensing device 100, similar to the eighth embodiment.

[0173] 10. Tenth Embodiment The following describes the tenth embodiment of this disclosure. The following description will focus on the differences from the first embodiment.

[0174] Figure 23 is a diagram illustrating the contraction process SS and expansion process SE in the tenth embodiment. This embodiment is the same as the sixth embodiment described above, except that a waveform for the vibration damping process SC is added to the second drive signal Com-B.

[0175] In this embodiment, the vibration damping process SC is executed when the potential of the second drive signal Com-B drops from the intermediate potential Vcb to the potential VLb1 after the expansion process SE. The potential VLb1 is the potential between the intermediate potential Vcb and the potential VLb.

[0176] The tenth embodiment described above also improves the discharge characteristics of the liquid discharge device 100. In this embodiment, in addition to the same effects as in the sixth embodiment, the effects of the vibration damping process SC are obtained.

[0177] 11. Variations Each of the above examples can be modified in various ways. Specific examples of modifications that can be applied to each of the aforementioned examples are given below. Note that two or more of the following examples can be arbitrarily selected and combined as appropriate, provided they do not contradict each other.

[0178] 11-1. Variation 1 Figure 24 is a diagram illustrating the shrinkage process SS and expansion process SE in modified example 1. Modification 1 is the same as the sixth embodiment described above, except that a step SX is added before the shrinking step SS.

[0179] In the example shown in Figure 24, the process SX is executed by repeatedly lowering the potential of the second drive signal Com-B from the intermediate potential Vcb to the potential VLb multiple times before the contraction process SS. The discharge characteristics of the liquid discharge device 100 can also be improved by the above modification 1. Note that the waveform used in process SX is not limited to the example shown in Figure 24 and can be arbitrary. According to process SX, for example, vibration can be generated to the extent that ink is not discharged, causing the pressure chamber C to expand immediately before period PS, and the vibration during discharge can be adjusted to excite the vibration. In addition, according to process SX, the intermediate potential Vcb, which is a high potential, is not always maintained in the standby state when no liquid is discharged, so the power consumption of the drive signal generation circuit 24 can be suppressed.

[0180] 11-2. Variation 2 In the above-described embodiment, a piezoelectric layer is interposed between individual electrodes and a common electrode, but the invention is not limited to this configuration, and a piezoelectric layer may be interposed between individual electrodes.

[0181] 11-3. Variation 3 In the embodiments described above, a serial-type liquid dispensing device 100 is exemplified, in which a carriage 41 equipped with a liquid dispensing head 50 is reciprocated. However, this disclosure can also be applied to a line-type liquid dispensing device in which multiple nozzles N are distributed across the entire width of the medium M.

[0182] 11-4. Variation 4 The liquid dispensing devices 100 exemplified in each of the above-described embodiments can be used in various devices such as facsimile machines and photocopiers, in addition to equipment dedicated to printing. However, the applications of the liquid dispensing devices of this disclosure are not limited to printing. For example, a liquid dispensing device that dispenses a colorant solution can be used as a manufacturing device for forming color filters for liquid crystal display devices. Also, a liquid dispensing device that dispenses a conductive material solution can be used as a manufacturing device for forming wiring and electrodes on a wiring board. [Explanation of symbols]

[0183] 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 discharge head, 51...Head tip, 51F...Piezoelectric element, 51a...Flow channel substrate, 51b...Pressure chamber substrate, 51b1...Partition wall, 51c...Nozzle plate, 51d...Vibration absorber, 51e...Vibrating plate, 51f...Piezoelectric element, 51f1...First electrode layer, 51f1a...Individual electrode, 51f1b...Individual electrode, 51f1c...Individual electrode, 51f2...Piezoelectric layer, 51f3...Second electrode layer, 51g...C Bar, 51h…Case, 51i…Wiring board, 52…Switching circuit, 52a…Connection status specification circuit, 100…Liquid discharge device, 200…External device, 51e1…First layer, 51e1…Second layer, ABO3…General composition formula, BD…Outer edge, C…Pressure chamber, CLK…Clock signal, CNG…Change signal, COM-A…First drive signal, Com-1…First drive signal, Com-A…First drive signal, Com-B…Second drive signal, EEa…Expansion element, EEa1…Expansion element, EEa2…Expansion element, EEb…Expansion element, EEb1…Expansion element, EEb2…Expansion element, ERa…Holding element, ERa1…Holding Element, ERa2...holding element, ERb...holding element, ERb1...holding element, ERb2...holding element, ESa...shrinking element, ESb...shrinking element, ESb1...shrinking element, ESb2...shrinking 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...communication channel, P1...active part, P1a...period, P1b...period, P1c...period, P1d...period, P2...active part, P2a...period, P2b...period, P2c...period, P2d...period, P3...active part, P3a...period, P3b...period Interval, P3c...period, P3d...period, P4a...period, P4b...period, P4c...period, P4d...period, P5a...period, P5b...period, P5c...period, P5d...period, P6c...period, P6d...period, P7c...period, P7d...period, PE...period, PE1...period, PE2...period, PS...period, R...liquid storage chamber, R1...opening, R2...container, Ra...supply channel, SC...vibration damping process, SE...expansion process, SE1...first expansion process, SE2...second expansion process, SI...printing data signal, SLa...connection status specification signal, SS...contraction process, SWa...switch, SWb...switch, SX...process,Sk1…Control signal, Sk2…Control signal, Tu…Unit period, VBS…Offset potential, VHV…Power supply potential, VHa…Potential, VHb…Potential, VLa…Potential, VLb…Potential, VLb1…Potential, Vca…Intermediate potential, Vcb…Intermediate potential, Vin-A…Supply signal, Vin-B…Supply signal, W1…Width, W2…Width, W3…Width, dCom…Waveform specification 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 laminated on the second surface and has a first active portion that overlaps with a center of the pressure chamber when viewed in a thickness direction of the vibration plate, and a second active portion that overlaps with the pressure chamber at a position closer to an outer edge of the pressure chamber than the first active portion; 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; the first drive signal includes a first contraction element that contracts the volume of the pressure chamber for each periodic unit period, the second drive signal includes a second contraction element for contracting a volume of the pressure chamber for each unit period, performing a contraction step in which a first period during which the first contraction element is supplied to the first active section and a second period during which the second contraction element is supplied to the second active section overlap each other; A liquid ejection device comprising:

2. During the contraction process, the magnitude relationship between the potentials of the first drive signal and the second drive signal is reversed. The liquid ejection device according to claim 1 .

3. In the unit period, a start timing of the first contraction element is later than a start timing of the second contraction element.

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

4. In the unit period, an end timing of the first contraction element is later than an end timing of the second contraction element.

4. The liquid ejection device according to claim 3.

5. the first drive signal includes a first expansion element that expands a volume of the pressure chamber for each unit period, the second drive signal includes a second expansion element that expands the volume of the pressure chamber for each unit period, performing an expansion step in which a third period during which the first expansion element is supplied to the first active portion and a fourth period during which the second expansion element is supplied to the second active portion overlap; 4. The liquid ejection device according to claim 1, wherein the liquid ejection device is a liquid ejection device.

6. In the unit period, the expansion step is performed prior to the contraction step.

6. The liquid ejection device according to claim 5.

7. In the unit period, the expansion step is performed after the contraction step.

6. The liquid ejection device according to claim 5.

8. The expansion step includes a first expansion step and a second expansion step, In the unit period, the contraction step is performed between the first expansion step and the second expansion step.

6. The liquid ejection device according to claim 5.

9. the first drive signal includes a first hold period that holds a voltage after the first contraction element; the second drive signal includes a second hold period that holds a voltage after the second contraction element; the first holding period and the second holding period have different lengths; 9. The liquid ejection device according to claim 7, wherein the liquid ejection device is a liquid ejection device.

10. The first drive signal and the second drive signal are signals having opposite phases to each other.

9. The liquid ejection device according to claim 7, wherein the liquid ejection device is a liquid ejection device.

11. In a standby state in which liquid is not ejected from the nozzle, the second drive signal maintains a state in which the volume of the pressure chamber is expanded.

10. The liquid ejection device according to claim 7, wherein the liquid ejection device is a liquid ejection device.

12. the first period and the fourth period do not overlap each other; the second time period and the third time period do not overlap with each other.

12. The liquid ejection device according to claim 5, wherein the liquid ejection device is a liquid ejection device.

13. 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 laminated on the second surface and has a first active portion that overlaps with a center of the pressure chamber when viewed in a thickness direction of the vibration plate, and a second active portion that overlaps with the pressure chamber at a position closer to an outer edge of the pressure chamber than the first active portion; 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; the first drive signal includes a first period during which the first drive signal changes from a first potential to a second potential, for each periodic unit period; the second drive signal includes a second period during which the second drive signal changes from a third potential to a fourth potential in each unit period; the first period and the second period overlap each other; A liquid ejection device comprising:

14. In a period in which the first period and the second period overlap each other, a magnitude relationship between the voltages of the first drive signal and the second drive signal is reversed. The liquid ejection device according to claim 13 .

15. In the unit period, a start timing of the first period is later than a start timing of the second period.

15. The liquid ejection apparatus according to claim 13 or 14.

16. The first drive signal is, for each unit period, a first hold period following the first period and in which the second potential is held; a third period following the first holding period, in which the potential changes from the second potential to a fifth potential; The second drive signal is, for each unit period, a second holding period following the second period and holding the fourth potential; a fourth period following the second holding period, in which the potential changes from the fourth potential to a sixth potential; the third period and the fourth period overlap each other; 16. The liquid ejection device according to claim 13,

17. In a period in which the third period and the fourth period overlap each other, a magnitude relationship between the potentials of the first drive signal and the second drive signal is reversed. The liquid ejection device according to claim 16 .

18. the first holding period and the second holding period have different lengths; 18. The liquid ejection apparatus according to claim 16 or 17.

19. the piezoelectric element has a third active portion that overlaps with the pressure chamber at a position closer to an outer edge of the pressure chamber than the first active portion in a thickness direction of the vibration plate, the first active portion is located between the second active portion and the third active portion in a thickness direction of the diaphragm; 19. The liquid ejection device according to claim 1,

20. the piezoelectric element has a first electrode layer, a piezoelectric layer, and a second electrode layer in this order in a direction away from the vibration plate; the piezoelectric layer and the second electrode layer are provided in common across the first active section, the second active section, and the third active section; the first electrode layer includes a plurality of individual electrodes provided respectively in the first active portion, the second active portion, and the third active portion; 20. The liquid ejection device according to claim 19.

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