Head chip, liquid jet head, and liquid jet device

Abstract

To provide a head chip, which is downsized and enables pressure chambers to be individually inspected.SOLUTION: The head chip comprises: a first nozzle that jets liquid; a second nozzle that jets liquid; a first pressure chamber communicating with the first nozzle; a second pressure chamber communicating with the first nozzle; a third pressure chamber communicating with the second nozzle; a fourth pressure chamber communicating with the second nozzle; a first piezoelectric body that generates pressure in the first pressure chamber; a second piezoelectric body that generates pressure in the second pressure chamber; a third piezoelectric body that generates pressure in the third pressure chamber; a fourth piezoelectric body that generates pressure in the fourth pressure chamber; a first individual electrode connected to the first piezoelectric body; a second individual electrode connected to the second piezoelectric body; a third individual electrode connected to the third piezoelectric body; a fourth individual electrode connected to the fourth piezoelectric body; a first common electrode connected to the first piezoelectric body and the third piezoelectric body in common; and a second common electrode connected to the second piezoelectric body and the fourth piezoelectric body in common, independently from the first common electrode.SELECTED DRAWING: Figure 7

Description

[Technical Field]

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

[0002] Liquid ejection devices, such as piezoelectric inkjet printers, generally include a pressure chamber that communicates with a nozzle and a piezoelectric element that generates pressure fluctuations in the pressure chamber. For example, as disclosed in Patent Document 1, there are cases in which multiple pressure chambers and multiple piezoelectric elements are provided for one nozzle.

[0003] The head unit described in Patent Document 1 includes a first pressure chamber and a second pressure chamber communicating with one nozzle, a first piezoelectric element corresponding to the first pressure chamber, a second piezoelectric element corresponding to the second pressure chamber, and a wiring substrate connected to a switch circuit. Here, each of the first and second piezoelectric elements includes a first electrode, a second electrode, and a piezoelectric layer sandwiched between the two electrodes. The first electrodes of the first and second piezoelectric elements are common electrodes connected to a common power supply line. In contrast, the second electrodes of the first and second piezoelectric elements are individual electrodes. Individual drive signals are sent from the switch circuit to the second electrodes of the first and second piezoelectric elements.

[0004] Incidentally, conventionally, there are cases where the natural frequency of a vibrating part formed by a piezoelectric element is measured, as disclosed in, for example, Patent Document 2. The method described in Patent Document 2 uses a measuring device called an impedance analyzer to measure the natural frequency of a vibrating part formed by a piezoelectric actuator based on the results of measuring the impedance when a specific sine wave is input to the piezoelectric actuator. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-104456 [Patent Document 2] Japanese Patent Application Publication No. 2018-51844 Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 1, separate drive signals are sent from a switch circuit to piezoelectric elements corresponding to two pressure chambers that communicate with a common nozzle. This increases the number of switching elements, which can result in an increase in the size of the wiring board on which the switch circuit is mounted and the possibility of the switch circuit overheating. Therefore, it is conceivable that sending a common drive signal to the individual electrodes of the two piezoelectric elements that correspond to a common nozzle would reduce the size of the wiring board and suppress heat generation in the switch circuit.

[0007] However, in Patent Document 1, two piezoelectric elements corresponding to a common nozzle are connected to the same common electrode, and a common power supply line is also used to supply power to the common electrode. Therefore, if Patent Document 1 adopts a configuration in which a common drive signal is sent to the individual electrodes of two piezoelectric elements corresponding to a common nozzle, it is not possible to separately measure the natural frequencies of the two vibration units corresponding to the common nozzle using the method described in Patent Document 2. Therefore, in this case, it is not possible to determine whether there is a difference in the characteristics of the two vibration units. Under these circumstances, in a configuration in which multiple pressure chambers are provided for one nozzle, it is desirable to reduce the size of the head chip, suppress heat generation, and test the performance of each pressure chamber. [Means for solving the problem]

[0008] In order to solve the above problems, a head chip according to a preferred embodiment of the present disclosure comprises a first nozzle for ejecting liquid, a second nozzle for ejecting liquid, a first pressure chamber communicating with the first nozzle, a second pressure chamber communicating with the first nozzle, a third pressure chamber communicating with the second nozzle, a fourth pressure chamber communicating with the second nozzle, a first piezoelectric element for generating pressure in the first pressure chamber, a second piezoelectric element for generating pressure in the second pressure chamber, a third piezoelectric element for generating pressure in the third pressure chamber, a fourth piezoelectric element for generating pressure in the fourth pressure chamber, a first individual electrode connected to the first piezoelectric element, a second individual electrode connected to the second piezoelectric element, a third individual electrode connected to the third piezoelectric element, a fourth individual electrode connected to the fourth piezoelectric element, a first common electrode connected in common to the first piezoelectric element and the third piezoelectric element, and a second common electrode independent of the first common electrode and connected in common to the second piezoelectric element and the fourth piezoelectric element.

[0009] A liquid jet head according to a preferred aspect of the present disclosure includes the head chip according to the above aspect, and a relay substrate connected to the head chip.

[0010] A liquid ejecting apparatus according to a preferred aspect of the present disclosure includes the liquid ejecting head according to the above aspect, and a wiring member connected to the liquid ejecting head. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram of a liquid ejecting apparatus according to a first embodiment. [Figure 2] FIG. 2 is a block diagram of a head unit of the liquid ejecting apparatus according to the first embodiment. [Figure 3] FIG. 1 is an exploded perspective view of a liquid jet head according to a first embodiment. [Figure 4] FIG. 4 is a diagram for explaining the operation of a drive circuit. [Figure 5] FIG. 2 is a cross-sectional view of the head chip according to the first embodiment. [Figure 6] FIG. 2 is a cross-sectional view of a piezoelectric element. [Figure 7]FIG. 2 is a schematic plan view illustrating a piezoelectric element according to the first embodiment. [Figure 8] FIG. 2 is a schematic diagram for explaining a wiring substrate in the first embodiment. [Figure 9] FIG. 2 is a schematic diagram for explaining a drive circuit in the first embodiment. [Figure 10] FIG. 2 is a schematic diagram illustrating a relay substrate in the first embodiment. [Figure 11] FIG. 10 is a diagram for explaining a performance test of a head chip. [Figure 12] FIG. 10 is a schematic plan view illustrating a piezoelectric element according to a second embodiment. [Figure 13] FIG. 10 is a schematic diagram for explaining a wiring substrate according to a second embodiment. [Figure 14] FIG. 10 is a schematic plan view illustrating a piezoelectric element according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Preferred embodiments of the present disclosure will be described below with reference to the accompanying drawings. Note that the dimensions and scale of each part in the drawings may differ from the actual dimensions and are shown schematically to facilitate understanding. Furthermore, the scope of the present disclosure is not limited to these embodiments unless otherwise specified in the following description to the effect that the present disclosure is limited.

[0013] For convenience, the following description will use the mutually intersecting X-axis, Y-axis, and Z-axis as appropriate. Hereinafter, one direction along the X-axis is the X1 direction, and the direction opposite the X1 direction is the X2 direction. Similarly, the opposite directions along the Y-axis are the Y1 direction and the Y2 direction. Furthermore, the opposite directions along the Z-axis are the Z1 direction and the Z2 direction. Hereinafter, viewing in the Z1 direction or the Z2 direction may be referred to as "planar view."

[0014] Here, the Z axis is typically 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 and may be inclined relative to the vertical axis. Furthermore, the X axis, Y axis, and Z axis are typically perpendicular to each other, but are not limited to this. For example, they may intersect at an angle between 80° and 100°.

[0015] 1. First embodiment 1-1.Liquid injection device FIG. 1 is a schematic diagram of a liquid ejection apparatus 100 according to a first embodiment. The liquid ejection apparatus 100 is an inkjet printing apparatus that ejects ink, an example of a liquid, as droplets onto a medium M. The liquid ejection apparatus 100 of this embodiment is a so-called line-type printing apparatus in which a plurality of nozzles that eject ink are distributed across the entire range in the width direction of the medium M. The medium M is typically printing paper. Note that the medium M is not limited to printing paper, and may be a printing target made of any material, such as a resin film or fabric.

[0016] As shown in FIG. 1, the liquid ejecting device 100 includes a liquid container 10, a control unit 20, a transport mechanism 30, a plurality of head units 40, and a circulation mechanism 50.

[0017] The liquid container 10 stores ink. Specific examples of the liquid container 10 include a cartridge that is detachable from the liquid ejection device 100, a bag-shaped ink pack made of flexible film, and an ink tank that can be refilled with ink. Any type of ink can be stored in the liquid container 10. The ink in the liquid container 10 is transferred to a subtank 51, which will be described later, by a pump 11 that is arranged between the liquid container 10 and the subtank 51.

[0018] The control unit 20 controls the operation of each element of the liquid ejection device 100. The control unit 20 includes, for example, a processing circuit such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array), and a storage circuit such as a semiconductor memory. Various programs and data are stored in the storage circuit. The processing circuit executes the programs and uses the data as appropriate to realize various controls.

[0019] The transport mechanism 30 transports the medium M under the control of the control unit 20. In the example shown in FIG. 1, the transport mechanism 30 transports the medium M in the Y1 direction. The transport mechanism 30 includes, for example, a long transport roller along the X axis and a motor that rotates the transport roller. Note that the transport mechanism 30 is not limited to a configuration using a transport roller, and may be configured, for example, to use a drum or endless belt that transports the medium M while adsorbed to its outer peripheral surface by electrostatic force or the like.

[0020] Each of the plurality of head units 40, under the control of the control unit 20, ejects ink supplied from the liquid container 10 via the circulation mechanism 50 onto the medium M from each of the plurality of nozzles.

[0021] In the example shown in FIG. 1, each of the multiple head units 40 has a liquid ejection head 41 and a drive module 42. The multiple liquid ejection heads 41 form a line head in which multiple nozzles are distributed across the entire range of the medium M in the X-axis direction, and eject ink in the Z2 direction. The drive module 42 drives the liquid ejection head 41 based on image information IP from the control unit 20. The image information IP is information based on data representing the image to be printed. Note that the number of head units 40 is not limited to the example shown in FIG. 1 and can be any number.

[0022] The circulation mechanism 50 is a mechanism that supplies ink to each head unit 40 and recovers ink discharged from each head unit 40 so that it can be resupplied to the head unit 40. The circulation mechanism 50 has, for example, a sub-tank 51 that stores ink supplied from the liquid container 10, a supply flow path 53 for supplying ink from the sub-tank 51 to the head unit 40, a recovery flow path 54 for recovering ink from the head unit to the sub-tank, and a pump 52 for transporting ink to each of these flow paths. The above operation of the circulation mechanism 50 can suppress an increase in the viscosity of the ink and reduce the accumulation of air bubbles in the ink.

[0023] 1-2.Head unit Fig. 2 is a block diagram of the head unit 40 of the liquid jet device 100 according to the first embodiment. As described above, the head unit 40 has a liquid jet head 41 and a driving module 42. The liquid jet head 41 and the driving module 42 are electrically connected to each other via a wiring member 43. Fig. 3 is an exploded perspective view of the liquid jet head 41. Note that Fig. 3 also illustrates the wiring member 43.

[0024] The wiring member 43 is a flexible member for electrically connecting the liquid jet head 41 and the drive module 42 to each other. Specifically, the wiring member 43 is, for example, a flexible printed circuit (FPC) or a flexible flat cable (FFC). Note that the configuration for electrically connecting the liquid jet head 41 and the drive module 42 to each other is not limited to a configuration using the wiring member 43, and may be, for example, a configuration using a BtoB (Board to Board) connector, or a configuration using both a BtoB connector and an FPC or an FFC.

[0025] 2, the drive module 42 has a control circuit 42a, a power supply circuit 42b, drive signal output circuits 42c_1 to 42c_m, and a conversion circuit 42d. Note that m is a natural number of 2 or more, and corresponds to the number of head chips 41a (described later) mounted on the liquid jet head 41. Furthermore, hereinafter, each of the drive signal output circuits 42c_1 to 42c_m may be referred to as a drive signal output circuit 42c. Furthermore, hereinafter, suffixes "_1" to "_m" are added to the reference numerals of elements corresponding to the drive signal output circuits 42c_1 to 42c_m.

[0026] The power supply circuit 42b receives power from a commercial power supply (not shown) and generates a power supply potential GVDD, a ground potential GND, a high-side power supply potential VHV, and a low-side power supply potential VDD. Each of these potentials is a constant potential. Specifically, for example, the power supply potential GVDD is approximately 7.5 V, the ground potential GND is approximately 0 V, the power supply potential VHV is approximately 42 V, and the power supply potential VDD is approximately 3.3 V. Each of these potentials is supplied to each of the drive signal output circuits 42c_1 to 42c_m. Of these potentials, the ground potential GND, the power supply potential VHV, and the power supply potential VDD are supplied to the liquid ejection head 41 via the wiring member 43 in addition to the drive signal output circuits 42c_1 to 42c_m.

[0027] The control circuit 42a is configured with a processing circuit such as a CPU or FPGA, and outputs various data and signals based on the image information IP input from the control unit 20.

[0028] Here, the control circuit 42a generates print data signals SI_1 to SI_m, a latch signal LAT, a change signal ch, and a clock signal SCK based on the image information IP. Each of the generated signals is input to the conversion circuit 42d. Each of the print data signals SI_1 to SI_m is a digital signal for specifying the type of operation of the piezoelectric element 400, which will be described later. Specifically, each of the print data signals SI_1 to SI_m specifies whether or not to supply drive signals COM_A and COM_B to the piezoelectric element 400, thereby specifying the type of operation of the piezoelectric element 400. The latch signal LAT and the change signal CH are used in conjunction with the print data signals SI_1 to SI_m to determine the drive timing of the piezoelectric element 400. The timing of the pulses included in these signals is determined based on the clock signal SCK. Note that, hereinafter, each of the print data signals SI_1 to SI_m may be referred to as a print data signal SI. Furthermore, each of the drive signals COM_A and COM_B may be referred to as a drive signal COM.

[0029] The conversion circuit 42d generates the data signal DATA by converting the print data signals SI_1 to SI_m, the latch signal LAT, the change signal CH, and the clock signal SCK into a differential signal such as LVDS (Low Voltage Differential Signaling). The data signal DATA is input to the liquid ejection head 41 via the wiring member 43. Note that the data signal DATA is not limited to LVDS, and may be, for example, a differential signal of a high-speed transfer method such as LVPECL (Low Voltage Positive Emitter Coupled Logic) or CML (Current Mode Logic), or a signal in which some or all of the print data signals SI_1 to SI_m, the latch signal LAT, the change signal ch, and the clock signal SCK are single-ended.

[0030] The control circuit 42a also generates drive data dA and dB, which are input to the drive signal output circuits 42c_1 to 42c_m, respectively.

[0031] The drive signal output circuit 42c generates a drive signal COM_A based on the drive data dA, and generates a drive signal COM_B based on the drive data dB. This generation uses a ground potential GND, a power supply potential VHV, and a power supply potential VDD. Here, for example, the drive signal output circuit 42c converts the drive data dA from a digital signal to an analog signal, and then performs class-D amplification on the analog signal to generate the drive signal COM_A. Similarly, the drive signal output circuit 42c converts the drive data dB from a digital signal to an analog signal, and then performs class-D amplification on the analog signal to generate the drive signal COM_B. Each of the drive signals COM_A and COM_B is input to the liquid ejection head 41 via a wiring member 43.

[0032] Furthermore, the drive signal output circuit 42c generates an offset potential VBS in addition to the drive signals COM_A and COM_B. The power supply potential GVDD is used for this generation. The offset potential VBS is a constant potential. The specific potential of the offset potential VBS is not particularly limited, and may be, for example, a constant potential of about 5.5 V or 6 V, or may be ground potential. The offset potential VBS is input to the liquid ejection head 41 via the wiring member 43. Note that the term "constant potential" includes cases where the potential can be considered constant when various fluctuations are taken into account, such as fluctuations in potential caused by the operation of peripheral circuits, fluctuations in potential caused by variations in circuit elements, and fluctuations in potential caused by the temperature characteristics of circuit elements.

[0033] The liquid jet head 41 has a restoration circuit 41b and head chips 41a_1 to 41a_m. As shown in Fig. 3, the liquid jet head 41 of this embodiment has six head chips 41a. Note that, hereinafter, each of the head chips 41a_1 to 41a_m may be referred to as head chip 41a.

[0034] The restoration circuit 41b restores the data signal DATA to a single-ended signal and separates it into signals corresponding to the head chips 41a_1 to 41a_m, respectively.

[0035] Specifically, the restoration circuit 41b restores the data signal DATA to generate print data signals SI_1 to SI_m, a latch signal LAT, a change signal ch, and a clock signal SCK. The restoration circuit 41b also separates the print data signals SI_1 to SI_m, the latch signal LAT, the change signal ch, and the clock signal SCK for each head chip 41a. Each separated signal is input to each head chip 41a. Here, the print data signals SI_1 to SI_m correspond to the head chips 41a_1 to 41a_m, respectively.

[0036] The restoration circuit 41b described above is mounted on a relay board 440. The relay board 440 is connected to the driving module 42 via a wiring member 43. Details of the relay board 440 will be described later with reference to FIG.

[0037] Here, drive signals COM_A, COM_B, offset potential VBS, ground potential GND, power supply potential VHV, and power supply potential VDD are supplied to each of head chips 41a_1 to 41a_m from drive module 42 via relay substrate 440. Also, as described above, print data signal SI, latch signal LAT, change signal CH, and clock signal SCK are input from restoration circuit 41b to each of head chips 41a_1 to 41a_m.

[0038] 3, the liquid jet head 41 includes a fixing plate 470, head chips 41a_1 to 41a_m, a holder 450, a relay substrate 440, and a flow path structure 460, which are stacked in this order. These stacked components constituting the liquid jet head 41 are fixed by fixing devices such as adhesives and screws (not shown).

[0039] The fixed plate 470 has six openings 471 penetrating the fixed plate 470 along the Z2 direction. The six head chips 41a are fixed to the surface of the fixed plate 470 facing the Z1 direction so that the nozzle substrates 413 of the head chips 41a are exposed from the six openings 471, respectively.

[0040] Holder 450 is located on the Z1 direction side of head chip 41a and accommodates head chip 41a between it and fixing plate 470. Two inlet portions 451 and two outlet portions 452 are provided on the surface of holder 450 facing the Z1 direction. Each of the two inlet portions 451 communicates with a first supply channel hole (not shown) formed on the surface of holder 450 facing the Z2 direction via a holder supply channel (not shown) formed inside holder 450. This first supply channel hole is connected to a supply port H1 of head chip 41a (described later). Each of the two outlet portions 452 communicates with a first discharge channel hole (not shown) formed on the surface of holder 450 facing the Z2 direction via a holder discharge channel (not shown) formed inside holder 450. This first discharge channel hole is connected to a discharge port H2 of head chip 41a (described later). Holder 450 also has six openings 453 penetrating along the Z1 direction. Wiring substrates 430 of the six head chips 41a are inserted into the six openings 453, respectively.

[0041] The relay substrate 440 is positioned in the Z1 direction of the holder 450. The relay substrate 440 has a connector 445 to which one end of a wiring member 43 for electrically connecting the drive module 42 and the liquid ejection head 41 is connected. The relay substrate 440 also has four openings 447 and two notches 448 formed therein. The wiring substrates 430 of the head chips 41a_2 to 41a_5 are inserted into the four openings 447. The wiring substrates 430 of the head chips 41a_2 to 41a_5 inserted into the four openings 447 are electrically connected to the relay substrate 440 by solder or the like. The wiring substrate 430 of the head chip 41a_1 passes through one of the notches 448, and the wiring substrate 430 of the head chip 41a_6 passes through the other of the notches 448. Then, the wiring substrates 430 of the head chips 41a_1 and 41a_6 that have passed through the two notches 448 are electrically connected to the relay substrate 440 by solder or the like.

[0042] The flow path structure 460 has two inlet portions 461 and two outlet portions 462 that protrude in the Z1 direction on a surface facing the Z1 direction. Each of the two inlet portions 461 communicates with a second supply flow path hole (not shown) formed on a surface of the flow path structure 460 facing the Z2 direction via a flow path (not shown) formed inside the flow path structure 460. This second supply flow path hole is connected to the inlet portion 451 of the holder 450. A supply flow path 53 formed by, for example, a tube is connected to the two inlet portions 461. Furthermore, each of the two outlet portions 472 communicates with a second discharge flow path hole (not shown) formed on a surface of the flow path structure 460 facing the Z2 direction via a flow path (not shown) formed inside the flow path structure 460. This second discharge flow path hole is connected to the outlet portion 452 of the holder 450. A recovery flow path 54 formed by, for example, a tube is connected to the two outlet portions 462.

[0043] Furthermore, the flow path structure 460 has a through hole 463 formed therethrough in the Z1 direction. A wiring member 43 that is electrically connected to the relay substrate 440 is inserted into the through hole 463. Note that a filter or the like may be provided inside the flow path structure 460 to capture foreign matter contained in the ink flowing through the flow paths formed inside the flow path structure 460.

[0044] Head chips 41a_1 to 41a_m have drive circuits 410_1 to 410_m that drive piezoelectric elements 400 (piezoelectric bodies), respectively. Drive circuits 410 will be described below. Head chip 41a will be described in detail later with reference to Figs. 5 to 8. Furthermore, hereinafter, each of drive circuits 410_1 to 410_m may be referred to as drive circuit 410.

[0045] The drive circuit 410 has multiple switching elements 410sw that switch whether or not to supply each of the drive signals COM_A and COM_B to the piezoelectric element 400 based on the clock signal SCK, the print data signal SI, the change signal CH, and the latch signal LAT. Here, of the waveforms included in the drive signals COM_A and COM_B, the waveform that is actually supplied to the piezoelectric element 400 is the drive signal VOUT. Of the pair of electrodes of the piezoelectric element 400, one electrode (an individual electrode 401 described below) is supplied with the drive signal VOUT, and the other electrode (a common electrode 403 described below) is supplied with an offset potential VBS. Note that examples of the change signal CH, the latch signal LAT, and the drive signals COM_A and COM_B will be described later with reference to FIG. 4.

[0046] The above-described driving circuit 410 is mounted on a wiring board 430. The wiring board 430 electrically connects the plurality of piezoelectric elements 400 to an intermediate board 440. Details of the wiring board 430 will be described later with reference to FIG.

[0047] As described above, the liquid jet device 100 includes the liquid jet head 41 and the wiring member 43 connected to the liquid jet head 41. Here, as described above, the liquid jet head 41 includes at least one head chip 41a and the relay substrate 440 connected to the head chip 41a.

[0048] 1-3. Operation of the driving circuit 410 FIG. 4 is a diagram illustrating the operation of the drive circuit 410. As shown in FIG. 4, the latch signal LAT includes a pulse PlsL for defining a unit period Tu. In the example shown in FIG. 4, the unit period Tu is defined as the period from the rising edge of a pulse PlsL to the rising edge of the next pulse PlsL. The unit period Tu corresponds to a printing cycle for forming dots of ink from the nozzles N on the medium M. In other words, the unit period Tu corresponds to the control cycle of the drive circuit 410 described above.

[0049] The change signal CH includes a pulse PlsC for dividing the unit period Tu into control periods Tu1 and Tu2. The control periods Tu1 and Tu2 are arranged in this order over time. The control period Tu1 is, for example, the period from the rising edge of the pulse PlsL to the rising edge of the first pulse PlsC. The control period Tu2 is, for example, the period from the rising edge of the first pulse PlsC to the rising edge of the subsequent second pulse PlsC. In the example shown in FIG. 4, the control periods Tu1 and Tu2 have the same time length, but this is not limited thereto, and the control periods Tu1 and Tu2 may have different time lengths. The change signal CH may also divide the unit period into three or more control periods.

[0050] The drive signal COM_A has a pulse PA1 provided in the control period Tu1 and a pulse PA2 provided in the control period Tu2. The drive signal COM_B has a pulse PB1 provided in the control period Tu1 and a pulse PB2 provided in the control period Tu2.

[0051] In the example shown in Figure 4, pulses PA1, PA2, and PB2 are each a potential pulse that drives the piezoelectric element 400 to generate pressure fluctuations in pressure chambers Ca and Cb (described below) that are strong enough to eject ink from nozzles N (described below). In contrast, pulse PB1 is a potential pulse that drives the piezoelectric element 400 to generate pressure fluctuations in pressure chambers Ca and Cb (described below) that are strong enough not to eject ink from nozzles N (described below). Note that the waveforms of pulses PA1, PA2, PB1, and PB2 are not limited to the example shown in Figure 4 and are arbitrary. Furthermore, pulse PB1 may be a potential pulse that drives the piezoelectric element 400 to generate pressure fluctuations in pressure chambers Ca and Cb (described below) that are strong enough to eject ink from nozzles N (described below).

[0052] The above pulses PA1, PA2, PB1, and PB2 are appropriately selected for each unit period Tu and used in the drive signal VOUT, which makes it possible to adjust the amount of ink ejected from the nozzle N, or to slightly vibrate the ink in the nozzle N without ejecting ink from the nozzle N.

[0053] 1-4.Head chip 5 is a cross-sectional view of head chip 41a according to the first embodiment. For convenience, the following description will use the X-axis, Y-axis, and Z-axis as well as the V-axis and W-axis as appropriate. Furthermore, one direction along the V-axis is the V1 direction, and the direction opposite to the V1 direction is the V2 direction. Similarly, the W1 direction and the W2 direction are opposite directions along the W-axis.

[0054] Here, the V axis is an axis along the nozzle row direction DN, which is the arrangement direction of the multiple nozzles N described below, and is an axis obtained by rotating the Y axis at a predetermined angle around the Z axis. The W axis is an axis obtained by rotating the X axis at the same predetermined angle around the Z axis. Therefore, the V axis and the W axis are typically perpendicular to each other, but are not limited to this. For example, they may intersect at an angle between 80° and 100°. Furthermore, the predetermined angle, i.e., the angle between the V axis and the Y axis or the angle between the W axis and the X axis, is, for example, between 40° and 60°.

[0055] 5, the head chip 41a has a flow path substrate 411, a pressure chamber substrate 412, a nozzle substrate 413, a vibration absorber 414, a vibration plate 415, a cover 416, a case 417, a plurality of piezoelectric elements 400, and a wiring substrate 430. Here, the pressure chamber substrate 412 and the vibration plate 415 constitute an actuator substrate 420 on which the plurality of piezoelectric elements 400 are mounted.

[0056] The flow path substrate 411 and the pressure chamber substrate 412 are layered in this order in the Z1 direction to form a plurality of individual flow paths P for supplying ink to a plurality of nozzles N. The plurality of individual flow paths P are aligned in a direction along the V axis. Each of the plurality of individual flow paths P is connected to a different nozzle N, and has a pressure chamber Ca, a pressure chamber Cb, a nozzle flow path Nf, a supply flow path Ra1, a discharge flow path Ra2, a first vertical flow path Na1, and a second vertical flow path Na2. Note that hereinafter, each of the pressure chambers Ca and Cb may be referred to as a pressure chamber C.

[0057] In an area located in the Z1 direction from the laminated body consisting of the flow path substrate 411 and the pressure chamber substrate 412, a vibration plate 415, multiple piezoelectric elements 400, covers 416 and 417, and a wiring substrate 430 are installed. On the other hand, in an area located in the Z2 direction from the laminated body, a nozzle substrate 413 and a vibration absorber 414 are installed. The elements of the head chip 41a are generally plate-like members that are elongated in the direction along the V axis, and are joined to each other, for example, by an adhesive. A plurality of nozzles N are provided on the nozzle substrate 413. The plurality of nozzles N are arranged in a direction along the V axis (nozzle row direction DN, described below). Each of the plurality of nozzles N is a through-hole that penetrates the nozzle substrate 413 and allows ink to pass through.

[0058] The pressure chamber substrate 412 is provided with a plurality of pressure chambers Ca and a plurality of pressure chambers Cb. The plurality of pressure chambers Ca are arranged in a direction along the V axis. The plurality of pressure chambers Cb are arranged in a direction along the V axis at positions in the W1 direction relative to the plurality of pressure chambers Ca. Here, the pressure chambers Ca and Cb corresponding to a common nozzle N are aligned in a direction along the W axis, and when viewed in the Z2 direction, which is the direction in which ink is ejected from the nozzle N, the nozzle N is disposed between the pressure chamber Ca and pressure chamber Cb corresponding to the common nozzle N. Each of the pressure chambers Ca and pressure chambers Cb penetrates the pressure chamber substrate 412, and forms a gap between the flow path substrate 411 and the vibration plate 415.

[0059] The flow path substrate 411 is provided with spaces R1a, R2a, a nozzle flow path Nf, a supply flow path Ra1, and a discharge flow path Ra2.

[0060] Each of the spaces R1a and R2a penetrates the flow path substrate 411 in the direction along the Z axis. Here, the space R1a constitutes a part of the first common liquid chamber R1. Furthermore, the space R2a constitutes a part of the second common liquid chamber R2. A vibration absorber 414 that closes the openings formed by the spaces R1a and R2a is installed on the surface of the flow path substrate 411 facing the Z2 direction.

[0061] The vibration absorber 414 is a layered member made of an elastic material. The vibration absorber 414 constitutes part of the wall surfaces of the first common liquid chamber R1 and the second common liquid chamber R2, and absorbs pressure fluctuations in the first common liquid chamber R1 and the second common liquid chamber R2.

[0062] The nozzle flow channel Nf is a space that connects the pressure chamber Ca and the pressure chamber Cb. In the example shown in FIG. 5, the nozzle flow channel Nf has a horizontal flow channel Nf1, a first vertical flow channel Na1, and a second vertical flow channel Na2. The horizontal flow channel Nf1 is a space within a groove provided on a surface of the flow channel substrate 411 facing the Z2 direction. Here, the nozzle substrate 413 constitutes part of the wall surface of the horizontal flow channel Nf1. The first vertical flow channel Na1 and the second vertical flow channel Na2 each extend along the Z axis and are spaces that penetrate the flow channel substrate 411. The first vertical flow channel Na1 connects the pressure chamber Ca and the horizontal flow channel Nf1, and guides ink from the pressure chamber Ca to the horizontal flow channel Nf1. On the other hand, the second vertical flow channel Na2 connects the pressure chamber Cb and the horizontal flow channel Nf1, and guides ink from the horizontal flow channel Nf1 to the pressure chamber Cb.

[0063] The supply flow path Ra1 and the discharge flow path Ra2 each extend along the Z axis and are spaces that penetrate the flow path substrate 411. The supply flow path Ra1 connects the first common liquid chamber R1 to the pressure chamber Ca, and supplies ink from the first common liquid chamber R1 to the pressure chamber Ca. One end of the supply flow path Ra1 opens to the surface of the flow path substrate 411 facing the Z1 direction. The other end of the supply flow path Ra1 is the upstream end of the individual flow path P, and opens to the wall surface of the first common liquid chamber R1 in the flow path substrate 411. On the other hand, the discharge flow path Ra2 connects the second common liquid chamber R2 to the pressure chamber Cb, and discharges ink from the pressure chamber Cb to the second common liquid chamber R2. One end of the discharge flow path Ra2 opens to the surface of the flow path substrate 411 facing the Z1 direction. On the other hand, the other end of the discharge flow path Ra2 is the downstream end of the individual flow path P, and opens into the wall surface of the second common liquid chamber R2 in the flow path substrate 411.

[0064] Diaphragm 415 is a plate-like member that can vibrate elastically. Details of diaphragm 415 will be described later with reference to FIG.

[0065] A plurality of piezoelectric elements 400 corresponding to different pressure chambers C are provided on the surface of the vibration plate 415 facing the Z1 direction. In a plan view, the piezoelectric elements 400 overlap the corresponding pressure chambers C. When a drive signal VOUT is supplied, the piezoelectric elements 400 deform, causing the vibration plate 415 to vibrate. This vibration causes the pressure chambers C to expand and contract, thereby fluctuating the pressure of the ink in the pressure chambers C.

[0066] The case 417 is a case for storing ink. Spaces R1b and R2b are provided in the case 417. The space R1b, together with the aforementioned space R1a, constitutes the first common liquid chamber R1. The space R2b, together with the aforementioned space R2a, constitutes the second common liquid chamber R2. The case 417 is also provided with a supply port H1 and a discharge port H2. The supply port H1 is a conduit communicating with the first common liquid chamber R1 and is connected to the supply flow path 53 of the circulation mechanism 50 via the aforementioned holder 450 and the flow path in the flow path structure 460. Therefore, ink from the circulation mechanism 50 is supplied to the first common liquid chamber R1 via the supply port H1. On the other hand, the discharge port H2 is a conduit communicating with the second common liquid chamber R2 and is connected to the recovery flow path 54 of the circulation mechanism 50 via the aforementioned holder 450 and the flow path in the flow path structure 460. As a result, the ink in the second common liquid chamber R2 is discharged to the circulation mechanism 50 via the discharge port H2.

[0067] Cover 416 is a plate-like member placed on the surface of diaphragm 415 facing the Z1 direction, and protects the plurality of piezoelectric elements 400 and reinforces the mechanical strength of diaphragm 415. Here, a space for accommodating the plurality of piezoelectric elements 400 is formed between cover 416 and diaphragm 415.

[0068] Wiring board 430 is mounted on the surface of diaphragm 415 facing the Z1 direction, and is a flexible wiring board such as an FPC (Flexible Printed Circuit) or an FFC (Flexible Flat Cable). Driving circuit 410 described above is mounted on wiring board 430.

[0069] In the head chip 41a configured as described above, ink is transferred in this order to the first common liquid chamber R1, supply flow path Ra1, pressure chamber Ca, nozzle flow path Nf, pressure chamber Cb, discharge flow path Ra2, and second common liquid chamber R2 by the operation of the circulation mechanism 50. The operation period or operation timing of the circulation mechanism 50 is arbitrary.

[0070] Furthermore, the piezoelectric elements 400 corresponding to both the pressure chamber Ca and the pressure chamber Cb that communicate with the common nozzle N are simultaneously driven by the drive signal VOUT from the drive circuit 410, thereby fluctuating the pressure in the pressure chamber Ca and the pressure chamber Cb, and in accordance with this pressure fluctuation, ink is ejected from the nozzle N. In Figure 5, the flow of ink when the piezoelectric elements 400 corresponding to both the pressure chamber Ca and the pressure chamber Cb are simultaneously driven is indicated by dashed arrows.

[0071] 1-5. Piezoelectric element and actuator substrate 6 is a cross-sectional view of the piezoelectric element 400. As described above, the actuator substrate 420 includes a pressure chamber substrate 412 having pressure chambers C, and a vibration plate 415. A piezoelectric element 400 is arranged for each pressure chamber C on the surface of the actuator substrate 420 facing the Z1 direction. The vibration plate 415 is laminated on the pressure chamber substrate 412.

[0072] 6, diaphragm 415 has a first layer 415a and a second layer 415b, which are stacked in this order in the Z1 direction. First layer 415a is an elastic film made of, for example, silicon oxide (SiO2). The elastic film is formed, for example, by thermally oxidizing one surface of a silicon single crystal substrate. Second layer 415b is an insulating film made of, for example, zirconium oxide (ZrO2). The insulating film is formed, for example, by forming a zirconium layer by sputtering and then thermally oxidizing the layer.

[0073] The first layer 415a is not limited to silicon oxide and may be made of other elastic materials such as silicon alone. The material of the second layer 415b is not limited to zirconium oxide and may be other insulating materials such as silicon nitride. Another layer such as a metal oxide may be interposed between the first layer 415a and the second layer 415b. A part or all of the diaphragm 415 may be made integral with the pressure chamber substrate 412 using the same material. The diaphragm 415 may also be made of a layer of a single material.

[0074] Note that the diaphragm 415 or at least a part of the diaphragm 415 (for example, the second layer 415b) may be configured integrally with the pressure chamber substrate 412. In other words, in this specification, "the diaphragm 415 is laminated on the pressure chamber substrate 412" does not only mean that the diaphragm 415 or a part of the diaphragm 415 is laminated on the pressure chamber substrate 412, which is made of a different material from the diaphragm 415 or a part of the diaphragm 415, and is fixed to the pressure chamber substrate 412, but also includes that the diaphragm 415 or a part of the diaphragm 415 is configured integrally with the pressure chamber substrate 412 using the same material.

[0075] The piezoelectric element 400 has an individual electrode 401, a piezoelectric body 402, and a common electrode 403, which are stacked in this order in the Z1 direction.

[0076] Note that other layers, such as layers for improving adhesion, may be interposed between the layers of the piezoelectric elements 400 or between the piezoelectric elements 400 and the vibration plate 415. A seed layer may be provided between the individual electrodes 401 and the piezoelectric bodies 402. The seed layer has the function of improving the orientation of the piezoelectric bodies 402 when the piezoelectric bodies 402 are formed. The seed layer may be made of, for example, titanium (Ti) or a composite oxide having a perovskite structure, such as Pb(Fe,Ti)O3.

[0077] The individual electrodes 401 are mounted on the actuator substrate 420 and are spaced apart from one another for each piezoelectric element 400. A drive signal VOUT is supplied to the individual electrodes 401. The individual electrodes 401 have, 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 individual electrodes 401 are formed by, for example, a known film formation technique such as sputtering, and a known processing technique using photolithography, etching, etc.

[0078] The configuration of the individual electrode 401 is not limited to the above example. For example, either the second or third layer may be omitted, or a layer made of iridium may be provided between the first and second layers. Furthermore, instead of or in addition to the second and third layers, a layer made of an electrode material other than iridium and platinum may be used. Examples of such electrode materials include metal materials such as aluminum (Al), nickel (Ni), gold (Au), and copper (Cu). One of these materials may be used alone, or two or more may be combined in the form of a laminate or alloy.

[0079] 6, the piezoelectric body 402 is disposed between the individual electrode 401 and the common electrode 403. In the example shown in Fig. 6, the piezoelectric body 402 is provided individually for each piezoelectric element 400. The piezoelectric body 402 may also be provided in common to a plurality of piezoelectric elements 400. In this case, the piezoelectric body 402 has a strip shape extending in the direction along the Y axis so as to be continuous across the plurality of piezoelectric elements 400.

[0080] The piezoelectric body 402 is made of a piezoelectric material having a perovskite-type crystal structure represented by the general composition formula ABO3. Specific examples of the piezoelectric material include lead titanate (PbTiO3), lead zirconate titanate (Pb(Zr,Ti)O3), lead zirconate (PbZrO3), lead lanthanum titanate ((Pb,La),TiO3), lead lanthanum zirconate titanate ((Pb,La)(Zr,Ti)O3), lead zirconium niobate titanate (Pb(Zr,Ti,Nb)O3), and lead magnesium zirconium niobate titanate (Pb(Zr,Ti)(Mg,Nb)O3). Among these, lead zirconate titanate is preferably used as the material for the piezoelectric body 402. The piezoelectric body 402 may contain small amounts of other elements, such as impurities.

[0081] Piezoelectric body 402 is formed by forming a precursor layer of the piezoelectric body by a liquid phase method such as a sol-gel method or a metal organic decomposition (MOD) method, and then baking and crystallizing the precursor layer. Here, piezoelectric body 402 may be formed of a single layer, but if it is formed of multiple layers, there is an advantage that the characteristics of piezoelectric body 402 can be easily improved even if the thickness of piezoelectric body 402 is increased.

[0082] The common electrode 403 is a strip-shaped common electrode that extends continuously along the Y-axis across the plurality of piezoelectric elements 400. An offset potential VBS is applied to the common electrode 403. As will be described later with reference to FIG. 7, the common electrode 403 is independent between the piezoelectric element 400 corresponding to the pressure chamber Ca and the piezoelectric element 400 corresponding to the pressure chamber Cb.

[0083] The common electrode 403 is made of a metal such as iridium (Ir), titanium (Ti), platinum (Pt), aluminum (Al), nickel (Ni), gold (Au), or copper (Cu), or an alloy or conductive oxide containing these metals. The common electrode 403 is formed by a known film formation technique such as sputtering, or a known processing technique using photolithography, etching, or the like. The common electrode 403 may be made of multiple layers.

[0084] FIG. 7 is a schematic plan view illustrating a piezoelectric element 400 according to the first embodiment. In FIG. 7, n nozzles N are shown as nozzles N_1 to N_n, pressure chambers Ca corresponding to the nozzles N_1 to N_n are shown as pressure chambers Ca_1 to Ca_n, and pressure chambers Cb corresponding to the nozzles N_1 to N_n are shown as pressure chambers Cb_1 to Cb_n. n is a natural number equal to or greater than 2 and is not particularly limited, but may be, for example, in the range of 200 to 600. Here, the nozzles N_1 to N_n are arranged in a nozzle row direction DN along the V axis, constituting a nozzle row LN. Also shown in FIG. 7 are a plurality of individual electrodes 401, a plurality of common electrodes 403, and a plurality of piezoelectric elements 402 arranged on an actuator substrate 420.

[0085] As shown in FIG. 7, head chip 41a has individual electrodes 401_A1 to 401_An, individual electrodes 401_B1 to 401_Bn, piezoelectric elements 402_A1 to 402_An, piezoelectric elements 402_B1 to 402_Bn, a first common electrode 403_A, and a second common electrode 403_B.

[0086] The individual electrodes 401_A1 to 401_An are the individual electrodes 401 corresponding to the pressure chambers Ca_1 to Ca_n, respectively. Similarly, the individual electrodes 401_B1 to 401_Bn are the individual electrodes 401 corresponding to the pressure chambers Cb_1 to Cb_n, respectively.

[0087] In this embodiment, the individual electrodes 401_A1 to 401_An and the individual electrodes 401_B1 to 401_Bn are independent on the actuator substrate 420. Here, each of the individual electrodes 401_A1 to 401_An has a terminal portion 401a for connection to the wiring substrate 430. Each of the individual electrodes 401_B1 to 401_Bn has a terminal portion 401b for connection to the wiring substrate 430. The terminal portions 401a and 401b are aligned in the nozzle row direction DN. In the example shown in FIG. 7, each of the nozzles N_1 to N_n is disposed between the corresponding terminal portion 401a and terminal portion 401b in a plan view.

[0088] Piezoelectric bodies 402_A1 to 402_An are piezoelectric bodies 402 corresponding to pressure chambers Ca_1 to Ca_n, respectively. Therefore, corresponding individual electrodes 401_A1 to 401_An are connected to piezoelectric bodies 402_A1 to 402_An. Similarly, piezoelectric bodies 402_B1 to 402_Bn are piezoelectric bodies 402 corresponding to pressure chambers Cb_1 to Cb_n, respectively. Therefore, corresponding individual electrodes 401_B1 to 401_Bn are connected to piezoelectric bodies 402_B1 to 402_Bn.

[0089] The first common electrode 403_A is the common electrode 403 corresponding to the pressure chambers Ca_1 to Ca_n. Therefore, the first common electrode 403_A is commonly connected to the piezoelectric bodies 402_A1 to 402_An. Here, the piezoelectric bodies 402_A1 to 402_An are located between the individual electrodes 401_A1 to 401_An and the first common electrode 403_A. Similarly, the second common electrode 403_B is the common electrode 403 corresponding to the pressure chambers Cb_1 to Cb_n. Therefore, the second common electrode 403_B is commonly connected to the piezoelectric bodies 402_B1 to 402_Bn. Here, the piezoelectric bodies 402_B1 to 402_Bn are located between the individual electrodes 401_B1 to 401_Bn and the second common electrode 403_B.

[0090] The first common electrode 403_A and the second common electrode 403_B are independent on the actuator substrate 420. That is, the first common electrode 403_A and the second common electrode 403_B are arranged on the actuator substrate 420 at an interval from each other.

[0091] Here, the first common electrode 403_A has two terminal portions 403a_A for connection to the wiring substrate 430. The two terminal portions 403a_A are arranged at or near both ends of the first common electrode 403_A in the nozzle row direction DN, and are aligned in the nozzle row direction DN on the same straight line as the plurality of terminal portions 401a and the plurality of terminal portions 401b described above.

[0092] Similarly, the second common electrode 403_B has two terminal portions 403a_B for connection to the wiring substrate 430. The two terminal portions 403a_B are arranged at or near both ends of the second common electrode 403_B in the nozzle row direction DN, and are aligned in the nozzle row direction DN on the same straight line as the plurality of terminal portions 401a and the plurality of terminal portions 401b. In the example shown in Fig. 7, the two terminal portions 403a_A are arranged between the two terminal portions 403a_B.

[0093] The individual electrodes 401_A1 to 401_An, the piezoelectric bodies 402_A1 to 402_An, and the first common electrode 403_A constitute piezoelectric elements 400_A1 to 400_An. The piezoelectric elements 400_A1 to 400_An are piezoelectric elements 400 corresponding to the pressure chambers Ca_1 to Ca_n. Similarly, the individual electrodes 401_B1 to 401_Bn, the piezoelectric bodies 402_B1 to 402_Bn, and the second common electrode 403_B constitute piezoelectric elements 400_B1 to 400_Bn. The piezoelectric elements 400_B1 to 400_Bn are piezoelectric elements 400 corresponding to the pressure chambers Cb_1 to Cb_n.

[0094] Here, of two nozzles N arbitrarily selected from the nozzles N_1 to N_n, one is the "first nozzle" and the other is the "second nozzle." Of the pressure chambers Ca and Cb communicating with the first nozzle, one is the "first pressure chamber" and the other is the "second pressure chamber." Of the pressure chambers Ca and Cb communicating with the second nozzle, one is the "third pressure chamber" and the other is the "fourth pressure chamber." However, hereinafter, for convenience of explanation, the nozzle N_1 will be referred to as the "first nozzle," the nozzle N_2 will be referred to as the "second nozzle," the pressure chamber Ca_1 will be referred to as the "first pressure chamber," the pressure chamber Cb_1 will be referred to as the "second pressure chamber," the pressure chamber Ca_2 will be referred to as the "third pressure chamber," and the pressure chamber Cb_2 will be referred to as the "fourth pressure chamber."

[0095] 1-6. Wiring board Fig. 8 is a schematic diagram for explaining a wiring board 430 in the first embodiment. As shown in Fig. 8, the wiring board 430 has a first common wiring 431_A1, a second common wiring 431_B1, a third common wiring 431_A2, a fourth common wiring 431_B2, two signal lines 432_A, two signal lines 432_B, wirings 433a, 433b, 433c, 434a, 434b, 434c, 434d, and individual wirings 435_1 to 435_n.

[0096] Here, the wiring substrate 430 has a first end E1 and a second end E2 facing in the opposite direction to the first end E1. The first end E1 is the end connected to the relay substrate 440. The second end E2 is the end connected to the actuator substrate 420. As shown in FIG. 5, the wiring substrate 430 of this embodiment is bent so that the first end E1 and the second end E2 are each along a plane perpendicular to the Z-axis. In the example shown in FIG. 8, the length of the first end E1 is shorter than the length of the second end E2. Furthermore, as described above, the driving circuit 410 is mounted on the wiring substrate 430.

[0097] The first common wiring 431_A1, the second common wiring 431_B1, the third common wiring 431_A2, and the fourth common wiring 431_B2 are wirings for transmitting the offset potential VBS. The first common wiring 431_A1, the second common wiring 431_B1, the third common wiring 431_A2, and the fourth common wiring 431_B2 are each provided from the first end E1 to the second end E2 without passing through the drive circuit 410.

[0098] Here, when viewed in the thickness direction of the wiring substrate 430, i.e., the direction along the W axis, the drive circuit 410 is arranged between the first common wiring 431_A1 and the second common wiring 431_B1 and the third common wiring 431_A2 and the fourth common wiring 431_B2. In the example shown in Fig. 8, the first common wiring 431_A1 and the second common wiring 431_B1 are arranged on the left side of the wiring substrate 430 in Fig. 8, and the third common wiring 431_A2 and the fourth common wiring 431_B2 are arranged on the right side of the wiring substrate 430 in Fig. 8. Furthermore, the first common wiring 431_A1 and the third common wiring 431_A2 are arranged between the second common wiring 431_B1 and the fourth common wiring 431_B2.

[0099] The first common wiring 431_A1 and the third common wiring 431_A2 are each connected to two terminal portions 403a_A of the actuator substrate 420 at the second end E2. Specifically, one of the two terminal portions 403a_A is connected to the first common wiring 431_A1, and the other is connected to the third common wiring 431_A2. Therefore, a constant offset potential VBS is supplied to the first common electrode 403_A via the first common wiring 431_A1 and the third common wiring 431_A2. As described above, the first common wiring 431_A1 and the third common wiring 431_A2 each electrically connect the first common electrode 403_A to the outside of the wiring substrate 430 without passing through the drive circuit 410.

[0100] Meanwhile, the second common wiring 431_B1 and the fourth common wiring 431_B2 are each connected to two terminals 403a_B of the actuator substrate 420 at the second end E2. Specifically, one of the two terminals 403a_B is connected to the second common wiring 431_B1, and the other is connected to the fourth common wiring 431_B2. Therefore, the second common electrode 403_B is supplied with an offset potential VBS, which is the same constant potential as that of the first common wiring 431_A1, via the second common wiring 431_B1 and the fourth common wiring 431_B2. As described above, the second common wiring 431_B1 and the fourth common wiring 431_B2 are independent of the first common wiring 431_A1 and the third common wiring 431_A2, and electrically connect the second common electrode 403_B to the outside of the wiring substrate 430 without passing through the drive circuit 410.

[0101] Each of the two signal lines 432_A is a wiring for transmitting a drive signal COM_A. Meanwhile, each of the two signal lines 432_B is a wiring for transmitting a drive signal COM_B. Each of the signal lines 432_A, 432_B extends from the first end E1 toward the drive circuit 410 and is connected to the drive circuit 410. Furthermore, each of the signal lines 432_A, 432_B is connected to the individual wirings 435_1 to 435_n via the drive circuit 410. As a result, each of the signal lines 432_A, 432_B electrically connects the outside of the wiring board 430 to the individual wirings 435_1 to 435_n via the drive circuit 410.

[0102] Here, the two signal lines 432_B and the two signal lines 432_A are arranged between the first common wiring 431_A1 and the third common wiring 431_A2. In the example shown in Fig. 8, the two signal lines 432_B are arranged between the two signal lines 432_A. Furthermore, one of the two signal lines 432_A and one of the two signal lines 432_B are arranged on the left side of the wiring board 430 in Fig. 8, and the other of the two signal lines 432_A and the other of the two signal lines 432_B are arranged on the right side of the wiring board 430 in Fig. 8.

[0103] The wiring 433a is a wiring for transmitting the power supply potential VDD. The wiring 433b is a wiring for transmitting the power supply potential VHV. The wiring 433c is a wiring for transmitting the ground potential GND. The wiring 434a is a wiring for transmitting the clock signal SCK. The wiring 434b is a wiring for transmitting the print data signal SI. The wiring 434c is a wiring for transmitting the latch signal LAT. The wiring 434d is a wiring for transmitting the change signal CH. Each of these wirings extends from the first end E1 toward the drive circuit 410 and is connected to the drive circuit 410.

[0104] 8, the wiring 433a, wiring 433b, wiring 433c, wiring 434a, wiring 434b, wiring 434c, and wiring 434d are arranged in this order. Note that the arrangement order of these wirings is not limited to the example shown in FIG. 8, and may be arbitrary.

[0105] The individual wirings 435_1 to 435_n are wirings for transmitting the drive signal VOUT. Each of the individual wirings 435_1 to 435_n extends from the second end E2 toward the drive circuit 410 and is connected to the drive circuit 410.

[0106] Here, the individual wirings 435_1 to 435_n correspond to the nozzles N_1 to N_n, respectively, and are arranged in the order of 435_1 to 435_n. In this manner, the individual wirings 435_1 to 435_n correspond to the individual electrodes 401_A1 to 401_An, respectively. Furthermore, the individual wirings 435_1 to 435_n correspond to the individual electrodes 401_B1 to 401_Bn, respectively. Each of the individual wirings 435_1 to 435_n is connected at the second end E2 to the corresponding individual electrode 401 of the actuator substrate 420, respectively.

[0107] In this embodiment, each of the individual wirings 435_1 to 435_n branches midway and extends toward the second end E2. Therefore, each of the individual wirings 435_1 to 435_n has two portions provided at the second end E2 by branching. The two portions are connected to the corresponding terminal portions 401a and 401b. For example, the individual wiring 435_1 branches at the wiring substrate 430 and is thereby electrically connected to each of the individual electrodes 401_A1 and 401_B1. As a result, a common drive signal VOUT is supplied to the two individual electrodes 401 corresponding to a common nozzle N.

[0108] Here, the switching elements 410sw of the drive circuit 410 will be described with reference to FIG. 9. FIG. 9 is a schematic diagram for explaining the drive circuit 410. The multiple switching elements 410sw include switching elements 410swa_1 to 410swa_n and switching elements 410swb_1 to 410swb_n. The switching elements 410swa_1 to 410swa_n are switching elements 410sw corresponding to each of the individual electrodes 401_A1 to 401_An and each of the individual electrodes 401_B1 to 401_Bn. The switching elements 410swa_1 to 410swa_n select whether or not to supply the drive signal COM_A to each piezoelectric element. The switching elements 410swb_1 to 410swb_n are switching elements 410sw corresponding to each of the individual electrodes 401_A1 to 401_An and each of the individual electrodes 401_B1 to 401_Bn. The switching elements 410swb_1 to 410swb_n select whether or not to supply the drive signal COM_B to each piezoelectric element 400.

[0109] To give a specific example, switching element 410swa_1 selects whether to supply drive signal COM_A to individual electrode 401_A1 and individual electrode 401_B1, switching element 410swa_2 selects whether to supply drive signal COM_A to individual electrode 401_A2 and individual electrode 401_B2, switching element 410swb_1 selects whether to supply drive signal COM_B to individual electrode 401_A1 and individual electrode 401_B1, and switching element 410swb_2 selects whether to supply drive signal COM_B to individual electrode 401_A2 and individual electrode 401_B2.

[0110] That is, a plurality of switching elements 410sw are provided corresponding to each of the plurality of nozzles N. In other words, for two individual electrodes 401 corresponding to the same nozzle N, a common switching element 410sw selects whether or not the drive signal COM_A or the drive signal COM_B is supplied to the two individual electrodes 401. With this configuration, the number of switching elements 410sw can be reduced compared to when separate switching elements 410sw are provided corresponding to each of the two individual electrodes 401, thereby enabling the drive circuit 410 to be made smaller and heat generation to be suppressed.

[0111] Here, the drive signal COM_A or the drive signal COM_B is an example of a "drive signal."

[0112] Furthermore, among the multiple switching elements 410sw, either switching element 410swa_1, which selects whether to supply drive signal COM_A to individual electrode 401_A1, which is an example of a "first individual electrode," and individual electrode 401_B1, which is an example of a "second individual electrode," corresponding to nozzle N_1, which is an example of a "first nozzle," or switching element 410swb_1, which selects whether to supply drive signal COM_B to individual electrode 401_A1, which is an example of a "first individual electrode," and individual electrode 401_B1, which is an example of a "second individual electrode," is an example of a "first switching element."

[0113] Similarly, among the multiple switching elements 410sw, either switching element 410swa_2, which selects whether to supply drive signal COM_A to individual electrode 401_A2, which is an example of a "third individual electrode," and individual electrode 401_B2, which is an example of a "fourth individual electrode," corresponding to nozzle N_2, which is an example of a "second nozzle," or switching element 410swb_2, which selects whether to supply drive signal COM_B to these individual electrodes, is an example of a "second switching element."

[0114] 1-7.Relay board Fig. 10 is a schematic diagram illustrating a relay substrate 440 according to the first embodiment. As shown in Fig. 10, the relay substrate 440 includes second relay wirings 441_1 and 441_2, two first relay wirings 442_A and two first relay wirings 442_B, and wirings 443a, 443b, 443c, 444a, 444b, 444c, and 444d. Fig. 10 illustrates a connector 445, an arbitrary one of a plurality of openings 447, a first end E1 of a wiring substrate 430 inserted into the opening 447, and the second relay wirings 441_1 and 441_2, two first relay wirings 442_A and two first relay wirings 442_B, and wirings 443a, 443b, 443c, 444a, 444b, 444c, and 444d corresponding to the wiring substrate 430. In Figure 10, for the sake of simplifying the illustration, the relative positional relationships between the connector 445, opening 447, connection portion 446, second relay wirings 441_1 and 441_2, two first relay wirings 442_A, two first relay wirings 442_B, and wirings 443a, 443b, 443c, 444a, 444b, 444c, and 444d differ from the actual positions.

[0115] Here, relay substrate 440 has connector 445. Connector 445 is a component for connecting to wiring member 43 described above. Relay substrate 440 has restoration circuit 41b described above, but is not shown in FIG. 10. Restoration circuit 41b may be disposed outside connector 445. Although not shown, connector 445 of this embodiment is connected to second relay wirings 441_1 and 441_2, two first relay wirings 442_A, two first relay wirings 442_B, and wirings 443a, 443b, 443c, 444a, 444b, 444c, and 444d corresponding to head chips 41a_1 to 41a_6, respectively.

[0116] The relay substrate 440 has a connection portion 446 that is a portion connected to the surface of the first end E1 of the wiring substrate 430 facing the Z2 direction.

[0117] Each of the second relay wirings 441_1 and 441_2 is a wiring for transmitting the offset potential VBS. Each of the second relay wirings 441_1 and 441_2 is provided from the connector 445 to the connection portion 446.

[0118] Here, the second relay wiring 441_1 is connected to both the first common wiring 431_A1 and the second common wiring 431_B1 of the wiring substrate 430 at the connection portion 446. On the other hand, the second relay wiring 441_2 is connected to both the third common wiring 431_A2 and the fourth common wiring 431_B2 of the wiring substrate 430 at the connection portion 446.

[0119] Each of the two first relay wirings 442_A is a signal line for transmitting a drive signal COM_A. Meanwhile, each of the two first relay wirings 442_B is a signal line for transmitting a drive signal COM_B. Each of the first relay wirings 442_A, 442_B is provided from the connector 445 to the connection portion 446.

[0120] Here, the two first relay wirings 442_A are connected to the two signal lines 432_A of the wiring board 430 at connection portions 446. On the other hand, the two first relay wirings 442_B are connected to the two signal lines 432_B of the wiring board 430 at connection portions 446.

[0121] The wiring 443a is a wiring for transmitting the power supply potential VDD. The wiring 443b is a wiring for transmitting the power supply potential VHV. The wiring 443c is a wiring for transmitting the ground potential GND. The wiring 444a is a wiring for transmitting the clock signal SCK. The wiring 444b is a wiring for transmitting the print data signal SI. The wiring 444c is a wiring for transmitting the latch signal LAT. The wiring 444d is a wiring for transmitting the change signal CH. Each of these wirings is provided from the connector 445 to the connection portion 446.

[0122] 10, the wiring 443a, wiring 443b, wiring 443c, wiring 444a, wiring 444b, wiring 444c, and wiring 444d are arranged in this order. Note that the arrangement order of these wirings is not limited to the example shown in FIG. 10, and may be arbitrary.

[0123] 1-8. Head tip inspection 11 is a diagram for explaining a performance test of head chip 41a. The performance test of head chip 41a is carried out using measuring instrument 200 and switches 300_A and 300_B in a state where relay board 440 is not connected to head chip 41a.

[0124] The measuring instrument 200 is an impedance analyzer that has a positive terminal and a negative terminal and measures the impedance between them. The test signal is, for example, a sine wave signal. Note that the measuring instrument 200 is not limited to an impedance analyzer and may be, for example, a current measuring instrument or a capacitance measuring instrument.

[0125] The positive terminal of measuring instrument 200 is electrically connected to the input side of drive circuit 410, specifically to at least one of signal line 432_A and signal line 432_B. Meanwhile, the negative terminal of measuring instrument 200 is connected to first common wiring 431_A1 and third common wiring _A2 via switch 300_A, thereby electrically connected to first common electrode 403_A. Furthermore, the negative terminal of measuring instrument 200 is connected to second common wiring 431_B1 and fourth common wiring _B2 via switch 300_B, thereby electrically connected to second common electrode 403_B. Measuring instrument 200 outputs a test signal as drive signal COM from its positive terminal. Furthermore, when a performance test of head chip 41a is performed, wirings 433a, 433b, 433c, 434a, 434b, 434c, and 434d are connected to a control device (not shown), and the control device controls the driving of drive circuit 410.

[0126] The switch 300_A switches between a state in which the first common electrode 403_A is electrically connected to the negative terminal of the measuring instrument 200 and a state in which the first common electrode 403_A is electrically connected to a constant potential VMB. The switch 300_B switches between a state in which the second common electrode 403_B is electrically connected to the negative terminal of the measuring instrument 200 and a state in which the second common electrode 403_B is electrically connected to a constant potential VMB. The constant potential VMB is not particularly limited, but is, for example, a constant potential in the range of 0 V to 35 V.

[0127] The inspection of the piezoelectric elements 400_A1 to 400_An is performed in a state in which the switch 300_A electrically connects the first common electrode 403_A to the negative terminal of the measuring instrument 200, and the switch 300_B electrically connects the second common electrode 403_B to a constant potential VMB. Here, when inspecting a desired piezoelectric element 400 among the piezoelectric elements 400_A1 to 400_An, the measuring instrument 200 controls the driving of the drive circuit 410 so that a drive signal VOUT, which is an inspection signal, is input only to the desired piezoelectric element 400. Specifically, when inspecting the piezoelectric element 400_A1, for example, the drive circuit 410 supplies the drive signal VOUT only to the individual wiring 435_1 connected to the piezoelectric element 400_A1. At this time, because the second common electrode 403_B is electrically connected to the constant potential VMB by the switch 300_B, the piezoelectric element 400_A1, not the piezoelectric element 400_B1, is placed between the positive terminal and the negative terminal of the measuring instrument 200. Therefore, even if the individual wiring 435_1 is a wiring common to the piezoelectric element 400_A1 and the piezoelectric element 400_B1, the impedance of only the piezoelectric element 400_A1 can be measured.

[0128] This is because the first common electrode 403_A connected to the piezoelectric elements 400_A1 to 400_An and the second common electrode 403_B connected to the piezoelectric elements 400_B1 to 400_Bn are independent, and the first common wiring 431_A1 and the third common wiring 431_A2 connected to the first common electrode 403_A are independent from the second common wiring 431_B1 and the fourth common wiring 431_B2 connected to the second common electrode 403_B, so that the switch 300_A connected to the first common electrode 403_A and the switch 300_B connected to the second common electrode 403_B can be provided separately.

[0129] On the other hand, the inspection of the piezoelectric elements 400_B1 to 400_Bn is performed in a state in which the switch 300_A electrically connects the first common electrode 403_A to the constant potential VMB and the switch 300_B electrically connects the second common electrode 403_B to the negative terminal of the measuring instrument 200. Here, when inspecting a desired one of the piezoelectric elements 400_B1 to 400_Bn, the measuring instrument 200 controls the driving of the driving circuit 410 so that the driving signal VOUT for inspection is input only to the desired one piezoelectric element 400. Specifically, when inspecting the piezoelectric element 400_B1, for example, the driving circuit 410 supplies the driving signal VOUT only to the individual wiring 435_1 connected to the piezoelectric element 400_B1. At this time, because the first common electrode 403_A is electrically connected to the constant potential VMB by the switch 300_A, the piezoelectric element 400_B1, not the piezoelectric element 400_A1, is placed between the positive terminal and the negative terminal of the measuring instrument 200. Therefore, even if the individual wiring 435_1 is a wiring common to the piezoelectric elements 400_A1 and 400_B1, the impedance of only the piezoelectric element 400_B1 can be measured.

[0130] As described above, the head chip 41a includes the nozzle N_1 which is an example of a "first nozzle," the nozzle N_2 which is an example of a "second nozzle," the pressure chamber Ca_1 which is an example of a "first pressure chamber," the pressure chamber Cb_1 which is an example of a "second pressure chamber," the pressure chamber Ca_2 which is an example of a "third pressure chamber," the pressure chamber Cb_2 which is an example of a "fourth pressure chamber," the piezoelectric body 402_A1 which is an example of a "first piezoelectric body," and the piezoelectric body 402_B1 which is an example of a "second piezoelectric body." 02_B1, a piezoelectric element 402_A2 which is an example of a "third piezoelectric element," a piezoelectric element 402_B2 which is an example of a "fourth piezoelectric element," an individual electrode 401_A1 which is an example of a "first individual electrode," an individual electrode 401_B1 which is an example of a "second individual electrode," an individual electrode 401_A2 which is an example of a "third individual electrode," an individual electrode 401_B2 which is an example of a "fourth individual electrode," a first common electrode 403_A, and a second common electrode 403_B.

[0131] Each of the nozzles N_1 and N_2 ejects ink, which is an example of "liquid." Each of the pressure chambers Ca_1 and Cb_1 communicates with the nozzle N_1. Each of the pressure chambers Ca_2 and Cb_2 communicates with the nozzle N_2. The piezoelectric element 402_A1 generates pressure in the pressure chamber Ca_1. The piezoelectric element 402_B1 generates pressure in the pressure chamber Cb_1. The piezoelectric element 402_A2 generates pressure in the pressure chamber Ca_2. The piezoelectric element 402_B2 generates pressure in the pressure chamber Cb_2. The individual electrode 401_A1 is connected to the piezoelectric element 402_A1. The individual electrode 401_B1 is connected to the piezoelectric element 402_B1. The individual electrode 401_A2 is connected to the piezoelectric element 402_A2. The individual electrode 401_B2 is connected to the piezoelectric element 402_B2. The first common electrode 403_A is commonly connected to the piezoelectric body 402_A1 and the piezoelectric body 402_A2. The second common electrode 403_B is independent of the first common electrode 403_A and commonly connected to the piezoelectric body 402_B1 and the piezoelectric body 402_B2.

[0132] In the above-described head chip 41a, the first common electrode 403_A and the second common electrode 403_B are independent of each other, and therefore even if a configuration is adopted in which a common drive signal VOUT is supplied to the individual electrodes 401 corresponding to a common nozzle N, signals can be supplied separately between the individual electrode 401_A1 or 401_A2 and the first common electrode 403_A, and between the individual electrode 401_B1 or 401_B2 and the second common electrode 403_B. This makes it possible to reduce the size of the head chip 41a and to individually test the performance of the piezoelectric element 400 for each pressure chamber C.

[0133] As described above, the head chip 41a is also provided with the first common liquid chamber R1 communicating with the pressure chambers Ca_1 and Ca_2, and the second common liquid chamber R2 communicating with the pressure chambers Cb_1 and Cb_2. This allows ink to be supplied to each pressure chamber Ca from the first common liquid chamber R1 or the second common liquid chamber R2, and ink to be collected from each pressure chamber Cb to the first common liquid chamber R1 or the second common liquid chamber R2.

[0134] As described above, the first common liquid chamber R1 is a flow path for supplying ink to the pressure chambers Ca_1 and Ca_2. The second common liquid chamber R2 is a flow path for recovering ink from the pressure chambers Cb_1 and Cb_2. This allows for an ink circulation configuration in which ink is supplied from the first common liquid chamber R1 to each pressure chamber Ca and ink is recovered from each pressure chamber Cb to the second common liquid chamber R2.

[0135] As described above, the head chip 41a includes a pressure chamber substrate 412 having pressure chambers Ca_1, Cb_1, Ca_2, and Cb_2, and a vibration plate 415 laminated on the pressure chamber substrate 412. Furthermore, the piezoelectric element 402_A1 is located between the individual electrode 401_A1 and the first common electrode 403_A. The piezoelectric element 402_B1 is located between the individual electrode 401_B1 and the second common electrode 403_B. The piezoelectric element 402_A2 is located between the individual electrode 401_A2 and the first common electrode 403_A. The piezoelectric element 402_B2 is located between the individual electrode 401_B2 and the second common electrode 403_B. This electrode arrangement allows performance testing of the head chip 41a for each pressure chamber C.

[0136] Furthermore, as described above, the head chip 41a has a nozzle row LN made up of a plurality of nozzles N aligned in the nozzle row direction DN. Nozzle N_1 and nozzle N_2 are aligned in the nozzle row direction DN and form part of the nozzle row LN. Therefore, when viewed in the direction of ink ejection from nozzle N_1 or nozzle N_2, nozzle N_1 can be disposed between pressure chamber Ca_1 and pressure chamber Cb_1, and nozzle N_2 can be disposed between pressure chamber Ca_2 and pressure chamber Cb_2.

[0137] As described above, the pressure chamber Ca_1 and the pressure chamber Cb_1 are aligned in a direction intersecting the nozzle row direction DN. The pressure chamber Ca_2 and the pressure chamber Cb_2 are aligned in a direction intersecting the nozzle row direction DN. The pressure chamber Ca_1 and the pressure chamber Ca_2 are aligned in the nozzle row direction DN. The pressure chamber Cb_1 and the pressure chamber Cb_2 are aligned in the nozzle row direction DN. Furthermore, the nozzle N_1 is disposed between the pressure chamber Ca_1 and the pressure chamber Cb_1 when viewed in the direction of ink ejection from the nozzle N_1 or the nozzle N_2. The nozzle N_2 is disposed between the pressure chamber Ca_2 and the pressure chamber Cb_2 when viewed in the direction of ink ejection from the nozzle N_1 or the nozzle N_2. Therefore, a voltage can be applied separately between the individual electrode 401_A1 or 401_A2 and the first common electrode 403_A, and between the individual electrode 401_B1 or 401_B2 and the second common electrode 403_B.

[0138] Furthermore, as described above, head chip 41a includes wiring substrate 430 on which piezoelectric elements 402_A1, 402_B1, and 402_A2, and drive circuit 410 for driving piezoelectric elements 402_B2, are mounted. Wiring substrate 430 has individual wiring 435_1, which is an example of a "first individual wiring," individual wiring 435_2, which is an example of a "second individual wiring," signal lines 432_A and 432_B, first common wiring 431_A1, and second common wiring 431_B1. Signal lines 432_A and 432_B electrically connect individual wiring 435_1 and individual wiring 435_2 to the outside of wiring substrate 430 via drive circuit 410. Individual wiring 435_1 electrically connects drive circuit 410 to individual electrode 401_A1 and individual electrode 401_B1. Therefore, a common drive signal can be supplied to the individual electrodes 401_A1 and 401_B1 using the individual wiring 435_1. The individual wiring 435_2 electrically connects the drive circuit 410 to the individual electrodes 401_A2 and 401_B2. Therefore, a common drive signal can be supplied to the individual electrodes 401_A2 and 401_B2 using the individual wiring 435_2.

[0139] The first common wiring 431_A1 electrically connects the outside of the wiring substrate 430 to the first common electrode 403_A without passing through the drive circuit 410. The second common wiring 431_B1 is independent of the first common wiring 431_A1 and electrically connects the outside of the wiring substrate 430 to the second common electrode 403_B without passing through the drive circuit 410. Therefore, a constant potential can be supplied to the first common electrode 403_A from the outside of the wiring substrate 430 using the first common wiring 431_A1, and a constant potential can be supplied to the second common electrode 403_B from the outside of the wiring substrate 430 using the second common wiring 431_B1.

[0140] As described above, the head chip 41a also includes an actuator substrate 420. The actuator substrate 420 has pressure chambers Ca_1, Cb_1, Ca_2, and Cb_2, and is mounted with individual electrodes 401_A1, 401_B1, 401_A2, and 401_B2. The individual wiring 435_1 branches off at the wiring substrate 430 and is electrically connected to each of the individual electrodes 401_A1 and 401_B1. The individual wiring 435_2 branches off at the wiring substrate 430 and is electrically connected to each of the individual electrodes 401_A2 and 401_B2. This makes it possible to realize a wiring substrate 430 that can be used for an actuator substrate 420 configured with an independent individual electrode for each pressure chamber C. Unlike the wiring board 430, such an actuator board 420 has independent individual wiring that does not branch out, and when the individual wiring is connected to a wiring board configured so that each individual wiring corresponds to each individual electrode, a head chip can be realized that separately drives two piezoelectric elements 400 corresponding to the same nozzle N.

[0141] Furthermore, as described above, the first common wiring 431_A1 supplies a constant potential to the first common electrode 403_A. The second common wiring 431_B1 supplies a constant potential that is the same as the potential of the first common wiring 431_A1 to the second common electrode 403_B. Therefore, each piezoelectric element 402 can be driven in the same way as if the first common electrode 403_A and the second common electrode 403_B were connected to one common electrode.

[0142] As described above, the signal lines 432_A and 432_B are supplied with drive signals COM_A and COM_B, respectively, for driving the piezoelectric elements 402_A1, 402_B1, 402_A2, and 402_B2. The drive circuit 410 includes a plurality of switching elements 410sw that select whether to supply the drive signal COM_A to the individual electrodes 401_A1 and 401_B1, and a plurality of switching elements 410sw that select whether to supply the drive signal COM_A to the individual electrodes 401_A2 and 401_B2. The drive circuit 410 also includes a plurality of switching elements 410sw that select whether to supply the drive signal COM_B to the individual electrodes 401_A1 and 401_B1, and a plurality of switching elements 410sw that select whether to supply the drive signal COM_B to the individual electrodes 401_A2 and 401_B2. Therefore, the number of switching elements 410sw can be reduced compared to a configuration in which separate switching elements 410sw are provided for multiple individual electrodes 401 corresponding to the same nozzle N. As a result, the drive circuit 410 can be made smaller.

[0143] Furthermore, as described above, the wiring substrate 430 has the third common wiring 431_A2 and the fourth common wiring 431_B2. The third common wiring 431_A2 is independent of the first common wiring 431_A1 and the second common wiring 431_B1, and electrically connects the outside of the wiring substrate 430 to the first common electrode 403_A without passing through the drive circuit 410. The fourth common wiring 431_B2 is independent of the first common wiring 431_A1, the second common wiring 431_B1, and the third common wiring 431_A2, and electrically connects the outside of the wiring substrate 430 to the second common electrode 403_B without passing through the drive circuit 410. In addition, the drive circuit 410 is disposed between the first common wiring 431_A1 and the second common wiring 431_B1 and the third common wiring 431_A2 and the fourth common wiring 431_B2 in the thickness direction of the wiring substrate 430. This makes it possible to supply a constant potential for the common electrode 403 near both ends in the longitudinal direction of the actuator substrate 420. As a result, it is possible to reduce a drop in the potential of the common electrode 403 due to differences in position in the nozzle row direction DN.

[0144] As described above, the liquid jet head 41 includes at least one head chip 41a and a relay substrate 440. The relay substrate 440 includes first relay wirings 442_A and 442_B electrically connected to the signal lines 432_A and 432_B, and a second relay wiring 441_1 electrically connected to the first common wiring 431_A1 and the second common wiring 431_B1. Therefore, the first common wiring 431_A1 and the second common wiring 431_B1 are commonized by the second relay wiring 441_1, thereby simplifying the routing of the wiring. Furthermore, the second relay wiring 441_1 can be made thicker, which prevents a drop in the potential of the first common wiring 431_A1 and the second common wiring 431_B1.

[0145] In this embodiment, as described above, the wiring substrates 430 of the plurality of head chips 41a are connected to the relay substrate 440. In this manner, when one liquid jet head 41 includes a plurality of head chips 41a, if performance testing cannot be performed for each head chip 41a, the yield during manufacturing of the liquid jet head 41 will be poor. Therefore, in this case, being able to perform performance testing for each head chip 41a is particularly useful in improving yield.

[0146] 2. Second embodiment A second embodiment of the present disclosure will be described below, focusing on the differences from the first embodiment.

[0147] 12 is a schematic plan view illustrating a piezoelectric element 400 according to the second embodiment. In this embodiment, the individual electrodes 401_A1 to 401_An and the individual electrodes 401_B1 to 401_Bn are electrically connected to each other on the actuator substrate 420 for each nozzle N. Here, the individual electrodes 401_A1 to 401_An and the individual electrodes 401_B1 to 401_Bn have terminal portions 401c for connection to the wiring substrate 430 for each nozzle N. The terminal portions 401c are aligned in the nozzle row direction DN. In the example shown in FIG. 12, each of the nozzles N_1 to N_n overlaps with the corresponding terminal portion 401c in a plan view.

[0148] 13 is a schematic diagram illustrating a wiring substrate 430 according to the second embodiment. In this embodiment, each of the individual wirings 435_1 to 435_n extends toward the second end E2 without branching. Each of the individual wirings 435_1 to 435_n is connected to a corresponding terminal portion 401c. As a result, a common drive signal VOUT is supplied to two individual electrodes 401 corresponding to a common nozzle N.

[0149] The second embodiment described above also makes it possible to miniaturize the head chip 41a and to individually test each pressure chamber C. In this embodiment, as described above, the individual electrodes 401_A1 and 401_B1 are electrically connected to each other on the actuator substrate 420. This allows the number of terminals on the wiring substrate 430 to be reduced.

[0150] As described above, one end of the individual wiring 435_1 is a terminal common to the individual electrodes 401_A1 and 401_B1, and one end of the individual wiring 435_2 is a terminal common to the individual electrodes 401_A2 and 401_B2, thereby reducing the number of terminals on the wiring substrate 430.

[0151] 3. Variations The above-described embodiments can be modified in various ways. Specific modifications that can be applied to the above-described embodiments are exemplified below. Any of the following embodiments can be combined as desired within the scope of their mutual compatibility.

[0152] 3. Third embodiment The third embodiment of the present disclosure will be described below, focusing on the differences from the first embodiment.

[0153] 14 is a schematic plan view illustrating a piezoelectric element 400 in the third embodiment. This embodiment is similar to the second embodiment described above, except that four pressure chambers C communicate with one nozzle N. Therefore, the number of piezoelectric elements 400 corresponding to the pressure chamber Ca and the number of piezoelectric elements 400 corresponding to the pressure chamber Cb are each n, while the number of nozzles N constituting the nozzle row LN is n / 2.

[0154] In this embodiment, ink is ejected from a common nozzle N by simultaneously driving the piezoelectric elements 400 corresponding to the four pressure chambers C that communicate with the nozzle N.

[0155] Here, of two nozzles N arbitrarily selected from the nozzles N_1 to N_n / 2, one is a "first nozzle" and the other is a "second nozzle." Of the two pressure chambers Ca and two pressure chambers Cb that communicate with the first nozzle, either pressure chamber Ca is an example of a "first pressure chamber," and either pressure chamber Cb is an example of a "second pressure chamber." Of the two pressure chambers Ca and two pressure chambers Cb that communicate with the second nozzle, either pressure chamber Ca is an example of a "third pressure chamber," and either pressure chamber Cb is an example of a "fourth pressure chamber." Furthermore, the individual electrode 401 corresponding to the "first pressure chamber" is a "first individual electrode," the individual electrode 401 corresponding to the "second pressure chamber" is a "second individual electrode," the individual electrode 401 corresponding to the "third pressure chamber" is a "third individual electrode," and the individual electrode 401 corresponding to the "fourth pressure chamber" is a "fourth individual electrode."

[0156] According to the third embodiment described above, the head chip 41a can be made smaller and heat generation can be suppressed, and each pressure chamber C can be inspected individually.

[0157] 4-1. Variation 1 In each of the above-described embodiments, a configuration using two types of drive signals COM_A and COM_B is exemplified, but the present invention is not limited to this configuration, and the number of types of drive signals input to the drive circuit 410 may be one, or three or more. Furthermore, the number of pulses included in the drive signal COM may be one, or three or more.

[0158] 4-2. Variation 2 In each of the above-described embodiments, a configuration in which multiple head chips 41a are mounted on the liquid ejection head 41 is exemplified, but this configuration is not limited to this, and the number of multiple head chips 41a mounted on the liquid ejection head 41 is arbitrary and may be as small as one.

[0159] 4-3. Variation 3 In each of the above-described embodiments, a configuration in which two or four pressure chambers C correspond to one nozzle N is exemplified, but this configuration is not limited to this, and the number of pressure chambers C corresponding to one nozzle N may be, for example, six or eight or more.

[0160] 4-4. Variation 4 In each of the above-described embodiments, a configuration is exemplified in which the ink used in the liquid jet head is circulated by a circulation mechanism, but the present invention is not limited to this configuration, and the configuration may not include such a circulation mechanism.

[0161] 4-5. Variation 5 In each of the above-described embodiments, a line-type liquid ejection device 100 in which multiple nozzles N are distributed across the entire width of the medium M has been exemplified, but the present invention can also be applied to a serial-type liquid ejection device in which a transport body equipped with a liquid ejection head 41 is moved back and forth in the width direction of the medium M.

[0162] 4-6. Variation 6 The liquid ejection device 100 exemplified in the above embodiment may be employed in various devices such as facsimile machines and copiers, in addition to devices dedicated to printing, and the use of the present invention is not particularly limited. However, the use of the liquid ejection device is not limited to printing. For example, a liquid ejection device that ejects a solution of a coloring material is used as a manufacturing device for forming color filters for display devices such as liquid crystal display panels. Furthermore, a liquid ejection device that ejects a solution of a conductive material is used as a manufacturing device for forming wiring and electrodes on a wiring board. Furthermore, a liquid ejection device that ejects a solution of an organic substance related to a living body is used as a manufacturing device for manufacturing biochips, for example.

[0163] 4-7. Variation 7 In the above embodiments, the drive module 42 constitutes the head unit 40 together with the liquid ejection head 41, but this is not limiting. For example, the drive module 42 may be part of the control unit 20. [Explanation of symbols]

[0164] 10...liquid container, 20...control unit, 30...transport mechanism, 34...pressure chamber substrate, 40...head unit, 41...liquid ejection head, 41a...head chip, 41a_1 to 41a_m...head chip, 41b...restoration circuit, 42...drive module, 42a...control circuit, 42b...power supply circuit, 42c...drive signal output circuit, 42c_1 to 42c_m...drive signal output circuit, 42d...conversion circuit, 43...wiring member, 45...drive circuit, 50...circulation mechanism, 100...liquid ejection device, 200...measuring instrument, 300_A...switch, 300_B...switch, 400...piezoelectric element, 400_A 1 to 400_An...piezoelectric elements, 400_B1 to 400_Bn...piezoelectric elements, 401...individual electrode, 401_A1...individual electrode (first individual electrode), 401_A2...individual electrode (third individual electrode), 401_B1...individual electrode (second individual electrode), 401_B2...individual electrode (fourth individual electrode), 401a...terminal portion, 401b...terminal portion, 401c...terminal portion, 402...piezoelectric body, 402_A1...piezoelectric body (first piezoelectric body), 402_A2...piezoelectric body (third piezoelectric body), 402_B1...piezoelectric body (second piezoelectric body), 402_B2...piezoelectric body (fourth piezoelectric body), 403...common electrode, 403_A...first common electrode, 403_B...second common electrode, 403a_A...terminal portion, 403a_B...terminal portion, 410...drive circuit, 410_1 to 410_m...drive circuit, 410sw...switching element, 411...flow path substrate, 412...pressure chamber substrate, 413...nozzle substrate, 414...vibration absorber, 415...diaphragm, 415a...first layer, 415b...second layer, 416...cover, 417...case, 420...actuator substrate, 430...wiring substrate, 431_A1...first common wiring, 431_A2...third common wiring, 431_B1...second common wiring, 431_B2...fourth common wiring, 432_A...signal line, 432_B...signal line, 433a...wiring, 433b...wiring, 433c...wiring, 434a...wiring, 434b...wiring, 434c...wiring, 434d...wiring, 435_1...individual wiring, 435_2...individual wiring, 440...relay board, 441_1...second relay wiring, 441_2...second relay wiring, 442_A...first relay wiring, 442_B...first relay wiring, 443a...wiring, 443b...wiring, 443c...wiring, 444a...wiring, 444b...wiring, 444c...wiring, 444d...wiring, 445...connector, 446...connection part, C...pressure chamber, CH...change signal, COM...drive signal,COM_A...drive signal, COM_B...drive signal, Ca...pressure chamber, Ca_1...pressure chamber (first pressure chamber), Ca_2...pressure chamber (third pressure chamber), Cb...pressure chamber, Cb_1...pressure chamber (second pressure chamber), Cb_2...pressure chamber (fourth pressure chamber), DATA...data signal, DN...nozzle row direction, E1...first end, E2...second end, GND...ground potential, GVDD...power supply potential, H1...supply port, H2...discharge port, IP...image information, LAT...latch signal, LN...nozzle row, M...medium, N...nozzle, N_1...nozzle (first nozzle), N_2...nozzle (second nozzle), Na1...first vertical flow path, Na2...second vertical flow path, Nf...nozzle flow path, Nf1 ...lateral flow path, P...individual flow path, PA1...pulse, PA2...pulse, PB1...pulse, PB2...pulse, PlsC...pulse, PlsL...pulse, R1...first common liquid chamber, R1a...space, R1b...space, R2...second common liquid chamber, R2a...space, R2b...space, Ra1...supply flow path, Ra2...discharge flow path, SCK...clock signal, SI...print data signal, SI_1 to SI_m...print data signal, Tu...unit period, Tu1...control period, Tu2...control period, VBS...offset potential, VDD...power supply potential, VHV...power supply potential, VMB...constant potential, VOUT...drive signal, ch...change signal, dA...drive data, dB...drive data.

Claims

1. A first nozzle for ejecting liquid; A second nozzle for ejecting liquid; a first pressure chamber communicating with the first nozzle; a second pressure chamber communicating with the first nozzle; a third pressure chamber communicating with the second nozzle; a fourth pressure chamber communicating with the second nozzle; a first piezoelectric body that generates pressure in the first pressure chamber; a second piezoelectric body that generates pressure in the second pressure chamber; a third piezoelectric body that generates pressure in the third pressure chamber; a fourth piezoelectric body that generates pressure in the fourth pressure chamber; a first individual electrode connected to the first piezoelectric body; A second individual electrode connected to the second piezoelectric body; a third individual electrode connected to the third piezoelectric body; a fourth individual electrode connected to the fourth piezoelectric body; a first common electrode connected in common to the first piezoelectric body and the third piezoelectric body; a second common electrode independent of the first common electrode and commonly connected to the second piezoelectric body and the fourth piezoelectric body; A head chip characterized by:

2. a first common liquid chamber communicating with the first pressure chamber and the third pressure chamber; a second common liquid chamber communicating with the second pressure chamber and the fourth pressure chamber; 2. The head chip according to claim 1.

3. the first common liquid chamber is a flow path for supplying liquid to the first pressure chamber and the third pressure chamber, the second common liquid chamber is a flow path for recovering liquid from the second pressure chamber and the fourth pressure chamber.

3. The head chip according to claim 2.

4. a pressure chamber substrate having the first pressure chamber, the second pressure chamber, the third pressure chamber, and the fourth pressure chamber; a vibration plate laminated on the pressure chamber substrate, the first piezoelectric body is located between the first individual electrode and the first common electrode, the second piezoelectric element is located between the second individual electrode and the second common electrode, the third piezoelectric element is located between the third individual electrode and the first common electrode, the fourth piezoelectric element is located between the fourth individual electrode and the second common electrode; 4. The head chip according to claim 1, wherein the first and second electrodes are arranged in a first direction.

5. A first nozzle flow path which is a space that communicates between the first pressure chamber and the second pressure chamber such that the first pressure chamber and the second pressure chamber are communicated with the first nozzle; a second nozzle flow path which is a space that communicates the third pressure chamber and the fourth pressure chamber such that the third pressure chamber and the fourth pressure chamber communicate with the second nozzle; 5. The head chip according to claim 1, wherein the first and second electrodes are arranged in a first direction.

6. An actuator substrate having the first pressure chamber, the second pressure chamber, the third pressure chamber, and the fourth pressure chamber; The first common electrode and the second common electrode are disposed on the actuator substrate.

6. The head chip according to claim 1, wherein the first and second electrodes are arranged in a first direction.

7. The nozzle array is made up of a plurality of nozzles aligned in a nozzle array direction, the first nozzles and the second nozzles are aligned in the nozzle row direction and form a part of the nozzle row; 7. The head chip according to claim 1, wherein the first and second electrodes are arranged in a first direction.

8. the first pressure chamber and the second pressure chamber are aligned in a direction intersecting the nozzle row direction, the third pressure chamber and the fourth pressure chamber are aligned in a direction intersecting the nozzle row direction, the first pressure chamber and the third pressure chamber are aligned in the nozzle row direction, the second pressure chamber and the fourth pressure chamber are aligned in the nozzle row direction, the first nozzle is disposed between the first pressure chamber and the second pressure chamber as viewed in a liquid ejection direction from the first nozzle or the second nozzle; the second nozzle is disposed between the third pressure chamber and the fourth pressure chamber as viewed in a liquid ejection direction from the first nozzle or the second nozzle. The head chip according to claim 7 .

9. a wiring board on which a drive circuit for driving the first piezoelectric element, the second piezoelectric element, the third piezoelectric element, and the fourth piezoelectric element is mounted, The wiring board includes: a first individual wiring that electrically connects the drive circuit to the first individual electrode and the second individual electrode; second individual wiring electrically connecting the drive circuit to the third individual electrode and the fourth individual electrode; a signal line electrically connecting an outside of the wiring board to the first individual wiring and the second individual wiring via the drive circuit; a first common wiring that electrically connects the outside of the wiring substrate to the first common electrode without passing through the drive circuit; a second common wiring that is independent of the first common wiring and electrically connects the outside of the wiring substrate to the second common electrode without passing through the drive circuit; 9. The head chip according to claim 1, wherein the first and second electrodes are arranged in a first direction.

10. an actuator substrate having the first pressure chamber, the second pressure chamber, the third pressure chamber, and the fourth pressure chamber, and on which the first individual electrode, the second individual electrode, the third individual electrode, and the fourth individual electrode are mounted, the first individual wiring is branched on the wiring substrate and electrically connected to the first individual electrode and the second individual electrode, the second individual wiring is branched at the wiring substrate to be electrically connected to the third individual electrode and the fourth individual electrode, The head chip according to claim 9 .

11. an actuator substrate having the first pressure chamber, the second pressure chamber, the third pressure chamber, and the fourth pressure chamber, and on which the first individual electrode, the second individual electrode, the third individual electrode, and the fourth individual electrode are mounted, the first individual electrode and the second individual electrode are electrically connected to each other on the actuator substrate; the third individual electrode and the fourth individual electrode are electrically connected to each other on the actuator substrate; The head chip according to claim 9 .

12. one end of the first individual wiring is a terminal common to the first individual electrode and the second individual electrode, one end of the second individual wiring is a terminal common to the third individual electrode and the fourth individual electrode; The head chip according to claim 11 .

13. the first common wiring supplies a constant potential to the first common electrode; the second common wiring supplies a constant potential, which is the same as that of the first common wiring, to the second common electrode; The head chip according to any one of claims 9 to 12.

14. a drive signal for driving the first piezoelectric element, the second piezoelectric element, the third piezoelectric element, and the fourth piezoelectric element is supplied to the signal line; the drive circuit includes a first switching element that selects whether or not to supply the drive signal to the first individual electrode and the second individual electrode, and a second switching element that selects whether or not to supply the drive signal to the third individual electrode and the fourth individual electrode.

14. The head chip according to claim 9, wherein the first and second electrodes are arranged in a first direction.

15. The wiring board includes: a third common wiring that is independent of the first common wiring and the second common wiring and electrically connects the outside of the wiring substrate to the first common electrode without passing through the drive circuit; a fourth common wiring that is independent of the first common wiring, the second common wiring, and the third common wiring and electrically connects an outside of the wiring substrate to the second common electrode without passing through the drive circuit; the drive circuit is disposed between the first common wiring and the second common wiring and between the third common wiring and the fourth common wiring in a thickness direction of the wiring substrate; 15. The head chip according to claim 9, wherein the first and second electrodes are arranged in a first direction.

16. At least one head chip according to any one of claims 9 to 15; A relay board, The relay substrate is a first relay wiring electrically connected to the signal line; a second relay wiring electrically connected in common to the first common wiring and the second common wiring; A liquid jet head comprising:

17. The at least one head chip is composed of a plurality of head chips, the relay substrate is connected to the wiring substrate of each of the plurality of head chips; The liquid jet head according to claim 16 .

18. The head chip according to any one of claims 1 to 15, A relay substrate connected to the head chip. A liquid jet head comprising:

19. The liquid jet head according to any one of claims 16 to 18, A wiring member connected to the liquid jet head. A liquid ejection apparatus comprising:

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