Piezoelectric actuator, liquid ejection head, and method of manufacturing the liquid ejection head

Abstract

To provide a piezoelectric actuator which prevents power concentration, a liquid discharge head, and a method for manufacturing a liquid discharge head.SOLUTION: A piezoelectric actuator includes an actuator part, and a conductor part. In the actuator part, a plurality of piezoelectric elements having a plurality of piezoelectric materials and internal electrodes are aligned, and inter-element grooves are formed between the adjacent piezoelectric elements in the alignment direction of the piezoelectric elements. The plurality of piezoelectric elements are provided through inter-array grooves. The conductor part has a plurality of electrode elements, which are provided in the inter-array grooves formed between the plurality of piezoelectric element arrays, and are composed of a conductive substance, aligned in the alignment direction, and has electrode arrays, in which inter-pole grooves are continuous to the inter-element grooves, formed between the adjacent electrode elements in the alignment direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] FIELD Embodiments of the present invention relate to a piezoelectric actuator, a liquid ejection head, and a method for manufacturing a liquid ejection head. [Background technology]

[0002] Various inkjet heads using piezoelectric materials such as PZT have been commercialized. For example, there is an inkjet head that uses an actuator unit in which a laminated piezoelectric member bonded to a base member is diced to form grooves, and a required number of piezoelectric pillars are formed in a comb-like shape at specified intervals on each piezoelectric member, with the upper end faces of the driving piezoelectric pillars bonded to a vibration plate to vibrate ink in a pressure chamber and eject ink droplets from a nozzle connected to the pressure chamber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5668382 Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the present invention is to provide a piezoelectric actuator, a liquid ejection head, and a method for manufacturing a liquid ejection head that are less susceptible to power concentration. [Means for solving the problem]

[0005] The piezoelectric actuator according to the embodiment The actuator section includes a plurality of rows of piezoelectric elements, each row having a plurality of stacked piezoelectric bodies and a plurality of internal electrodes, arranged in a row, with an inter-element groove formed between each of the piezoelectric elements adjacent in the arrangement direction of the piezoelectric elements, and a conductor section including an electrode row, each row having a plurality of electrode elements made of a conductive material filled in the inter-row grooves formed between the plurality of piezoelectric element rows, arranged in parallel in the arrangement direction, and an inter-electrode groove continuous with the inter-element grooves formed between the electrode elements adjacent in the arrangement direction, and the plurality of electrode elements are connected to a plurality of internal electrodes in each piezoelectric element. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a cross-sectional view showing the configuration of a portion of an inkjet head according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing a configuration of a part of the inkjet head. [Figure 3] 3A to 3C are explanatory diagrams showing a method of manufacturing the inkjet head. [Figure 4] 3A to 3C are explanatory diagrams showing a method of manufacturing the inkjet head. [Figure 5] 5A to 5C are explanatory diagrams showing a method for manufacturing an inkjet head. [Figure 6] 3A to 3C are explanatory diagrams showing a method of manufacturing the inkjet head. [Figure 7] 3A to 3C are explanatory diagrams showing a method of manufacturing the inkjet head. [Figure 8] FIG. 1 is an explanatory diagram showing a schematic configuration of an inkjet recording apparatus according to a first embodiment. [Figure 9] FIG. 10 is a cross-sectional view showing a configuration of a portion of an inkjet head according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] An inkjet head 1, which is a liquid ejection head, and an inkjet recording apparatus 100, which is a liquid ejection apparatus, according to a first embodiment will be described below with reference to FIGS. 1 to 8. FIGS. 1 and 2 are cross-sectional views showing the schematic configuration of a portion of the inkjet head 1. FIGS. 3 to 7 are explanatory diagrams showing a method for manufacturing an inkjet head. FIG. 8 is an explanatory diagram showing the schematic configuration of the inkjet recording apparatus 100. In the figures, arrows X, Y, and Z indicate three mutually orthogonal directions. For the sake of explanation, the configuration in each figure is enlarged, reduced, or omitted as appropriate.

[0008] As shown in FIG. 1, the inkjet head 1 includes a piezoelectric actuator 2, a vibration plate 30, a manifold 40, a nozzle plate 50 having a plurality of nozzles 51, and a wiring board .

[0009] The piezoelectric actuator 2 comprises a base 10 as a support member, an actuator unit 20 as an actuator section having a pair of piezoelectric element rows 201, 202, a conductor section 227 arranged between the pair of piezoelectric element rows 201, 202, and external electrodes 224 formed on the outer side surfaces of the pair of piezoelectric element rows 201, 202, respectively.

[0010] As shown in FIGS. 1 and 2 , the base 10 holds the actuator unit 20 having a plurality of piezoelectric element rows 201, 202. The base 10 is made of a processable material such as SUS or alumina, and the piezoelectric element rows 201, 202 are bonded to one end surface of the base 10. The base 10 has a conductive portion that forms part of the inter-row groove 25 and is connected to the conductor portion 227 in the inter-row groove 25. In one embodiment, for example, the base 10 is made of a conductive material, and the entire base 10 serves as a conductive portion. The inter-row groove 25 is formed up to the base 10, so that the base 10 forms part of the inner surface of the inter-row groove 25. The base 10 is connected to the conductor portion 227 formed in the inter-row groove 25, and the base 10 itself, which is a conductive portion, forms part of the wiring of the common electrode. In addition, the base 10 may have wiring for routing a common electrode, which is composed of a conductor portion 227 in a groove formed on the inner side surface on which the two piezoelectric element rows 201, 202 face each other, to the outer end surface of the actuator unit 20; for example, the common electrode may be connected to a common wiring layer of the wiring board 70 via the base 10.

[0011] The actuator unit 20 is composed of a laminated piezoelectric member 200 in which a plurality of piezoelectric layers 211, dummy layers 212, and internal electrodes 221, 222 are laminated. The actuator unit 20 is divided on one side in the lamination direction of the laminated piezoelectric member 200 by an inter-row groove 25 and a plurality of inter-element grooves 22, and includes a plurality of piezoelectric element rows 201, 202 arranged with the inter-row groove 25 interposed therebetween.

[0012] The piezoelectric element rows 201, 202 have inter-row grooves 25 and inter-element grooves 22 formed in the laminated piezoelectric member 200, and thus have a pair of plate-shaped bases 26 arranged in parallel via the inter-row grooves 25, and a plurality of columnar piezoelectric elements 21 each extending to one side of the pair of bases 26 in the stacking direction and arranged in parallel via the inter-element grooves 22.

[0013] Base 26 is formed, for example, in a plate shape, and is joined to one end in the stacking direction of base 10, which is a support member. Base 26 has a recess 261, where a corner is cut out by a predetermined amount, at the end on the base 10 side, at the outer end opposite inter-row groove 25. Recess 261 has a part of its outer surface receding inward and separated from base 10, thereby avoiding interference with wiring board 70 and other components.

[0014] Each piezoelectric element 21 is configured in a columnar shape extending to one side of the base 26. The piezoelectric element 21 includes a plurality of piezoelectric layers 211 stacked in a first direction, dummy layers 212 disposed on both ends in the stacking direction, and internal electrodes 221, 222 formed on the main surface of each piezoelectric layer 211. As an example, each piezoelectric element 21 has 50 or fewer stacked piezoelectric layers 211, each layer has a thickness of 10 μm to 40 μm, and the product of the thickness and the total number of stacked layers is less than 1000 μm.

[0015] The piezoelectric layer 211 is formed in a thin plate shape from a piezoelectric material such as PZT (lead zirconate titanate) or lead-free KNN (potassium sodium niobate), etc. The multiple piezoelectric layers 211 are stacked with their thickness direction aligned in the first direction, and are bonded to each other via adhesive layers.

[0016] The dummy layer 212 is made of the same material as the piezoelectric layer 211. For example, it is disposed on both ends of the region of the piezoelectric layer 211 where the internal electrodes 221 and 222 are formed, i.e., on both sides in the stacking direction. The dummy layer 212 has an electrode on only one side, so it is not subjected to an electric field and does not deform. In other words, the dummy layer 212 does not function as a piezoelectric layer, but serves as a base for fixing or as a polishing allowance for polishing to achieve precision during and after assembly.

[0017] The internal electrodes 221 and 222 are conductive films formed into a predetermined shape using a sinterable conductive material such as silver-palladium. The internal electrodes 221 and 222 are formed in predetermined regions on the main surfaces of each piezoelectric layer 211. The internal electrodes 221 and 222 have opposite polarities. For example, one internal electrode 221 is formed in a region that reaches one end of the piezoelectric layer 211 but does not reach the other end in the second direction, indicated by the Y direction in the figure. The second direction is perpendicular to or intersects with the first direction, which is the stacking direction. The other internal electrode 222 is formed in a region that does not reach one end of the piezoelectric layer 211 but reaches the other end in the second direction, indicated by the Y direction in the figure. The internal electrode 221 is connected to an external electrode 224 formed on the outer surface of the piezoelectric element 21, and the internal electrode 222 is connected to an inner electrode element 2271.

[0018] The plurality of inter-element grooves 22 extend in the second direction and divide each of the piezoelectric element rows 201, 202 into a plurality of piezoelectric elements 21. The inter-element grooves 22 are formed between adjacent piezoelectric elements 21 in a third direction, which is the arrangement direction. The third direction is a direction that is perpendicular to or intersects with the first and second directions. In this embodiment, the first direction is along the Z direction, the second direction is along the Y direction, and the third direction is along the X direction.

[0019] The inter-row groove 25 extends in the third direction and is disposed between the pair of piezoelectric element rows 201, 202 in the second direction. The inter-row groove 25 separates the pair of piezoelectric element rows 201, 202. The depth dimension of the inter-row groove 25 in the stacking direction is formed to be deeper than the depth dimension of the inter-element grooves 22. For example, the inter-row groove 25 penetrates the actuator unit 20 in the depth direction, which is the stacking direction, and is formed to a depth that reaches the base 10. In other words, a portion of the bottom side of the inter-row groove 25 is formed by the base 10.

[0020] The external electrode 224 is formed on the outer side surface opposite the inter-row groove 25 of the piezoelectric element rows 201, 202, each having a plurality of piezoelectric elements 21, and is formed by gathering the ends of the internal electrodes 221. The external electrode 224 is formed as a film of Ni, Cr, Au, or the like by a known method such as plating or sputtering.

[0021] The conductor portion 227 is provided in the inter-row groove 25 between the pair of piezoelectric element rows 201, 202. The conductor portion 227 is made of a conductive material such as silver paste or a conductive adhesive, and integrally includes a plurality of columnar electrode elements 2271 arranged via inter-electrode grooves 2273, which are third grooves communicating with the inter-element grooves 22, and connecting portions 2272 arranged at the bottom of the plurality of electrode elements 2271. After a paste or liquid conductive material such as silver paste or a conductive adhesive is filled into the inter-row groove 25 and hardened, the conductor portion 227 is divided at one end side in the stacking direction by forming a plurality of inter-electrode grooves 2273 that connect to the plurality of inter-element grooves 22, and the plurality of electrode elements 2271 and connecting portions 2272 that are integrally continuous at the bottom side of the electrode elements 2271 are formed integrally.

[0022] Each electrode element 2271 is arranged at the same position as the plurality of piezoelectric elements 21 in the arrangement direction of the piezoelectric elements 21, and is connected to each of the plurality of piezoelectric elements 21. That is, in the extension direction perpendicular to the stacking direction and the arrangement direction of the piezoelectric elements 21, the piezoelectric elements 21 of one piezoelectric element row 201, the electrode element 2271, and the piezoelectric elements 21 of the other piezoelectric element row 202 are arranged continuously in a line. Similarly, in the extension direction, the inter-element grooves 22 of one piezoelectric element row 201, the inter-electrode grooves 2273, and the inter-element grooves 22 of the other piezoelectric element row 202 are arranged continuously in a line. Therefore, each electrode element 2271 is connected to the internal electrode 222 in each piezoelectric element 21.

[0023] As an example in this embodiment, the inner conductor portion 227 on the opposing surface side of the pair of piezoelectric element rows 201, 202 serves as a common electrode, and the outer external electrode 224 serves as an individual electrode. The external electrodes 224, which serve as individual electrodes for the multiple piezoelectric elements 21, are divided by inter-element grooves 22 formed between the multiple piezoelectric elements 21 and are configured to be able to be driven independently of each other. The conductor portions 227, which serve as common electrodes on the opposing surface side, are connected by connecting portions 2272 in a bottom region closer to the base 10 than the inter-electrode grooves 2273, to form the common electrode.

[0024] The external electrodes 224 serving as individual electrodes are connected to, for example, the wiring board 70, and are connected to mounted components such as the driving IC 71 via various wirings.

[0025] When a voltage is applied to the internal electrodes 221 and 222 via the external electrode 224 and the conductor portion 227, each piezoelectric element 21 vibrates longitudinally along the stacking direction of the piezoelectric layer 211. For example, the longitudinal vibration referred to here means "vibration in the thickness direction defined by the piezoelectric constant d33." In this embodiment, as an example shown in FIG. 1, half of the piezoelectric elements 21 arranged in parallel, every other one, are arranged in correspondence with the pressure chambers 31 across the vibration plate 30, and the remaining half of the piezoelectric elements 21 are arranged in positions facing the partition wall portion 42 across the vibration plate 30.

[0026] The vibration plate 30 is disposed, for example, with its thickness direction aligned with the stacking direction, and extends in a plane direction perpendicular to the stacking direction. The vibration plate 30 is bonded to one side of the plurality of piezoelectric elements 21 in the stacking direction, i.e., to the surface on the nozzle plate 50 side. The vibration plate 30 includes, for example, a deformable plate portion and a plurality of, for example, protruding joint portions that are bonded to the piezoelectric elements 21 of the actuator unit 20. For example, the surfaces of the joint portions of the vibration plate 30 are bonded to the end faces of the piezoelectric elements 21.

[0027] The vibration plate 30 is bonded to one end surface of the piezoelectric element 21. As an example, in this embodiment, the vibration plate 30 is bonded to the manifold 40. The vibration plate 30 deforms in accordance with the deformation of the piezoelectric element 21, thereby changing the volume of the pressure chamber 31.

[0028] The manifold 40 is bonded to one side of the vibration plate 30. The manifold 40 forms a predetermined ink flow path having a plurality of pressure chambers 31 and a common chamber that communicates with the plurality of pressure chambers 31. The manifold 40 is provided with a plurality of partition walls 42 that separate the pressure chambers 31. The partition walls 42 are wall members that separate the plurality of pressure chambers 31 in the arrangement direction and form both side sides of the pressure chambers 31. The partition walls 42 are disposed opposite the piezoelectric elements 21 across the vibration plate 30 and are supported by the piezoelectric elements 21.

[0029] Each pressure chamber 31 communicates with a nozzle 51 formed in a nozzle plate 50 disposed on one side in the stacking direction. The pressure chamber 31 is closed by a vibration plate 30 on the opposite side of the nozzle plate 50.

[0030] The pressure chambers 31 communicate with the common chamber, hold liquid supplied from the common chamber, and are deformed by vibration of the vibration plate 30 that forms part of the pressure chambers 31, thereby ejecting the liquid from the nozzles 51.

[0031] The nozzle plate 50 is configured as a rectangular plate with a thickness of approximately 10 μm to 100 μm, made of a metal such as SUS or Ni, or a resin material such as polyimide. The nozzle plate 50 is disposed on one side of the manifold 40 so as to cover the openings on one side of the pressure chambers 31. The nozzle plate 50 has a plurality of nozzles 51 formed therethrough in the thickness direction. The nozzles 51 are aligned in the third direction to form a nozzle row. Each nozzle 51 is provided at a position corresponding to one of the pressure chambers 31.

[0032] Wiring board 70 is a wiring substrate such as an FPC having an electrode layer formed in a predetermined pattern. Wiring board 70 has individual wiring connected to external electrodes 224, which are individual electrodes, and common wiring connected to conductor portion 227, which is a common electrode. For example, wiring board 70 is connected to driving IC 71.

[0033] For example, each external electrode 224 and conductor portion 227 is connected by wiring to a drive circuit 1161 of the control unit 116 as a drive unit via a drive IC 71, and is configured to be drive-controllable by control such as a CPU (Central Processing Unit) possessed by the drive circuit 1161.

[0034] In the inkjet head 1 configured as described above, the nozzle plate 50, the manifold 40, and the diaphragm 30 form an ink flow path having a plurality of pressure chambers 31 communicating with the nozzles 51 and a common chamber communicating with the plurality of pressure chambers 31. For example, the common chamber is connected to an ink tank 132 via a connection flow path 133, and ink from the ink tank 132 is supplied to each pressure chamber 31 via the common chamber.

[0035] In the inkjet head 1, when the control unit 116 applies a driving voltage to the internal electrodes 221, 222 to be driven by the driving IC 71, the piezoelectric elements 21 vibrate in the stacking direction, i.e., in the thickness direction of each piezoelectric layer 211. In other words, the piezoelectric elements 21 vibrate longitudinally. Specifically, the control unit 116 applies a driving voltage to the internal electrodes 221, 222 of the piezoelectric elements 21 to be driven, thereby selectively driving the piezoelectric elements 21 to be driven. Then, the driving of the piezoelectric elements 21 deforms the vibration plate 30 by combining deformation in the tensile direction and deformation in the compressive direction, and changes the volume of the pressure chambers 31, thereby directing liquid from the common chamber and ejecting it from the nozzles 51.

[0036] A method for manufacturing an inkjet head according to this embodiment will be described with reference to Fig. 3 to Fig. 7. First, in the method for manufacturing the piezoelectric actuator 2, internal electrodes 221, 222 are printed on a sheet-shaped piezoelectric material to form piezoelectric layers 211 on which the internal electrodes 221, 222 are formed. Then, a plurality of piezoelectric layers 211 each having the internal electrodes 221, 222 are stacked and fired to form the multilayer piezoelectric member 200 shown in Fig. 3 and Fig. 4. Then, the multilayer piezoelectric member 200 on which the internal electrodes 221, 222 have been formed in advance is placed on a base 10 made of a workable and hard material such as SUS or alumina.

[0037] 5, an inter-row groove 25 is formed in the center of the laminated piezoelectric member 200 by dicing, and the laminated piezoelectric member is divided into two rows. At this time, the end of the inner side surface of each laminated piezoelectric member, which is on the inter-row groove 25 side, facing the base 10, is positioned closer to the base 10 than the end of the external electrode 224 on the outer side surface, facing the base 10.

[0038] Next, in the laminated piezoelectric member 200, the external electrodes 224 are formed by printing on the outer end faces of the pair of laminated piezoelectric members 200. In addition, a corner of the outer side of the laminated piezoelectric member 200 facing the base 10 is partially cut out to form a recess 261. 6, a paste or liquid conductive material such as silver paste or conductive adhesive is filled into the inter-row grooves 25. For example, depending on the viscosity of the conductive material, if the viscosity is low, the conductive material can be filled into the inter-row grooves 25 by dripping it near the inter-row grooves 25 and using surface tension, or if the viscosity is high, the conductive material can be pushed in with a spatula or the like. After filling, the conductive material is hardened by heat or the like to form a conductive solid.

[0039] After the conductive material in the inter-row grooves 25 has hardened, a plurality of inter-element grooves 22 and inter-pole grooves 2273 extending continuously in the second direction are simultaneously formed at a predetermined pitch in the conductive solid by dicing or the like, dividing one side of the laminated piezoelectric member 200 and the conductor portion 227 into a plurality of parts, thereby forming piezoelectric element rows 201, 202 each having a plurality of piezoelectric elements 21, and an electrode row 2270 each having a plurality of electrode elements 2271.

[0040] Here, the inter-element grooves 22 have a depth that reaches a position deeper than the portion where the external electrodes 224 formed on the outside are formed, and the external electrodes 224 are spaced apart from one another to form independent individual electrodes for each piezoelectric element 21. On the other hand, the inter-row grooves 25 are continuous in a portion closer to the base 10 than the bottoms of the inter-element grooves 22, and therefore the conductor portions 227 are integrally connected in a region closer to the base 10 than the external electrodes 224 and inter-element grooves 22.

[0041] The conductor portion 227 in the inter-row groove 25 is connected to the internal electrodes 221 of both piezoelectric element rows 201, 202 and constitutes part of a common electrode common to the pair of piezoelectric element rows 201, 202. Note that the conductor portion 227 in the groove, which is the common electrode, may be routed to the other side surface. In this way, the actuator unit 20 is formed.

[0042] Then, the piezoelectric elements 21 are polarized. Furthermore, the wiring board 70 is connected to the external electrodes 224, which serve as individual electrodes, by soldering. At this time, as shown in Fig. 7, one end of the actuator unit 20 is fixed on a support tool 81, the wiring board 70 is brought into contact with the external electrodes 224, which serve as individual electrodes, and pressure is applied with a pressure tool 82 to mount the wiring board 70. At this time, the piezoelectric elements 21 of the pair of piezoelectric element rows 201, 202 are connected by electrode elements 2271, and each piezoelectric element 21 is supported in the pressure direction, which facilitates the joining process.

[0043] Furthermore, the manifold 40 and frame members are joined, and the nozzle plate 50 is adhered with the nozzles 51 arranged to face each pressure chamber 31, and the inkjet head 1 is completed.

[0044] An example of an inkjet recording apparatus 100 equipped with the inkjet head 1 will be described below with reference to Fig. 8. The inkjet recording apparatus 100 includes a housing 111, a medium supply unit 112, an image forming unit 113, a medium discharge unit 114, a conveying device 115, and a control unit 116.

[0045] The inkjet recording device 100 is a liquid ejection device that performs an image formation process on paper P by ejecting a liquid such as ink while transporting the paper P as a printing medium, which is the ejection target, along a predetermined transport path A that runs from a medium supply section 112 through an image forming section 113 to a medium ejection section 114.

[0046] The housing 111 constitutes the outer shell of the inkjet recording apparatus 100. The housing 111 is provided at a predetermined location with an outlet for discharging the paper P to the outside.

[0047] The medium supply unit 112 includes a plurality of paper feed cassettes, and is configured to be able to hold a stack of multiple sheets of paper P of various sizes.

[0048] The medium discharge unit 114 includes a paper discharge tray configured to be able to hold the paper P discharged from the discharge port.

[0049] The image forming section 113 includes a support section 117 that supports the paper P, and a plurality of head units 130 that are disposed above the support section 117 and face each other.

[0050] The support section 117 includes a conveyor belt 118 that is looped in a predetermined area where image formation is performed, a support plate 119 that supports the conveyor belt 118 from the back side, and a plurality of belt rollers 120 that are provided on the back side of the conveyor belt 118.

[0051] During image formation, the support unit 117 supports the paper P on a holding surface, which is the upper surface of the conveyor belt 118, and conveys the paper P downstream by moving the conveyor belt 118 at a predetermined timing by the rotation of the belt roller 120.

[0052] The head unit 130 includes multiple (four color) inkjet heads 1, ink tanks 132 as liquid tanks mounted on each inkjet head 1, a connection flow path 133 connecting the inkjet heads 1 and the ink tanks 132, and a supply pump 134.

[0053] In this embodiment, the inkjet heads 1 are provided with four colors, cyan, magenta, yellow, and black, and ink tanks 132 that contain ink of each color. The ink tanks 132 are connected to the inkjet heads 1 by connecting channels 133.

[0054] A negative pressure control device such as a pump (not shown) is connected to the ink tank 132. The negative pressure control device controls the negative pressure inside the ink tank 132 in accordance with the head value between the inkjet head 1 and the ink tank 132, thereby causing the ink supplied to each nozzle 51 of the inkjet head 1 to form a meniscus of a predetermined shape.

[0055] The supply pump 134 is a liquid transfer pump formed, for example, by a piezoelectric pump. The supply pump 134 is provided in the supply flow path. The supply pump 134 is connected to a drive circuit 1161 of the control unit 116 by wiring, and is configured to be controllable by a CPU (Central Processing Unit). The supply pump 134 supplies liquid to the inkjet head 1.

[0056] The conveying device 115 conveys the paper P along a conveying path A that runs from the medium supply unit 112 through the image forming unit 113 to the medium discharge unit 114. The conveying device 115 includes a plurality of guide plate pairs 121 and a plurality of conveying rollers 122 that are arranged along the conveying path A.

[0057] Each of the guide plate pairs 121 includes a pair of plate members arranged opposite each other with the paper P being conveyed therebetween, and guides the paper P along the conveying path A.

[0058] The conveying rollers 122 are driven to rotate under the control of the control unit 116, thereby sending the paper P downstream along the conveying path A. Sensors for detecting the conveying status of the paper are arranged at various points along the conveying path A.

[0059] The control unit 116 includes a control circuit such as a CPU which is a controller, a ROM (Read Only Memory) which stores various programs, a RAM (Random Access Memory) which temporarily stores various variable data and image data, and an interface unit which inputs data from the outside and outputs data to the outside.

[0060] In the inkjet recording apparatus 100 configured as described above, when the control unit 116 detects a print instruction entered by a user operating the operation input unit via an interface, for example, the control unit 116 drives the transport device 115 to transport the paper P and outputs a print signal to the head unit 130 at a predetermined timing, thereby driving the inkjet head 1. For the inkjet head 1's ejection operation, the control unit 116 sends a drive signal to the drive IC 71 in response to an image signal corresponding to image data, which applies a drive voltage to the internal electrodes 221 and 222 to selectively drive the piezoelectric elements 21 and vibrate them vertically in the stacking direction, thereby changing the volume of the pressure chambers 31 to eject ink from the nozzles 51 and form an image on the paper P held on the conveyor belt 118. For the liquid ejection operation, the control unit 116 drives the supply pump 134 to supply ink from the ink tank 132 to the common chamber of the inkjet head 1.

[0061] The piezoelectric actuator 2, inkjet head 1, and manufacturing method of the inkjet head 1 according to the above-described embodiments provide a piezoelectric actuator 2, an inkjet head 1, and a manufacturing method of the inkjet head 1 that are less susceptible to power concentration. Specifically, by forming the conductor portion 227 constituting the common electrode in the inter-row groove 25 formed between a pair of piezoelectric element rows 201, 202, the area of ​​the common electrode can be secured, preventing current concentration in the wiring of the common electrode. This avoids a shortage of charge supply. Furthermore, forming the conductor portion 227 in the inter-row groove 25 allows the common electrode to be formed, simplifying wiring formation. By forming the conductor portion 227 in the inter-row groove 25 common to multiple piezoelectric element rows 201, 202, only one common electrode wiring is required, simplifying the wiring structure of the common electrode. Furthermore, since the pair of piezoelectric element rows 201, 202 are bonded to the base 10 while connected together, bonding is easy and positional accuracy of the multiple piezoelectric element rows 201, 202 can be ensured. Furthermore, by making the base 10 conductive, the resistance can be reduced and wiring can be easily led out.

[0062] Furthermore, in the inkjet head 1 according to the above embodiment, the pair of piezoelectric elements 21 are connected by the electrode element 2271 in the inter-row groove 25, and therefore when a compressive force is applied in the extension direction, the pair of piezoelectric elements 21 are supported by the electrode element 2271, facilitating bonding by pressure application. In other words, for example, if there is a hollow space between the pair of piezoelectric element rows 201, 202, it becomes difficult to support the pair of piezoelectric element rows in the pressure direction, making bonding difficult.

[0063] The present invention is not limited to the above-described embodiment, and in the implementation stage, the components can be modified and embodied without departing from the spirit of the invention.

[0064] For example, the method for manufacturing the inkjet head is not limited to the above, and may be a method in which a plurality of laminated piezoelectric members 200, each formed individually in a row, are bonded to the base 10. In this case, by attaching a plurality of laminated piezoelectric members 200 to the base 10 at a predetermined distance, inter-row grooves 25 are formed between them. Then, after filling the inter-row grooves 25 formed between the plurality of laminated piezoelectric members 200 with a conductive material and curing it, similar to the above embodiment, a plurality of grooves are formed in the plurality of laminated piezoelectric members 200 and the cured conductive material, and inter-element grooves 22 and inter-electrode grooves 2273 are formed, thereby forming a piezoelectric element array having a plurality of piezoelectric elements 21 and an electrode array 2270 having a plurality of electrode elements 2271.

[0065] In the above embodiment, the base 10 is made of a conductive material, but this is not limiting. For example, a portion of the surface or a portion of the interior of the base 10 may be conductive. Alternatively, a conductive layer connected to the conductor portion 227 may be separately formed on the surface of a base made of a non-conductive material. In addition, in the above embodiment, an example was shown in which the inter-row groove 25 was formed deep enough to separate the laminated piezoelectric member 200 into two and reach the base 10, but as another embodiment, for example, as in the actuator unit 1020 shown in Figure 9, the inter-row groove 25 may be deep enough not to reach the base 10, or may be shallower than the surface of the base 10, and the bases 26 of the two rows of piezoelectric elements may be continuous and integrated.

[0066] Furthermore, although the above embodiment has exemplified a laminated type piezoelectric element 21, a single layer piezoelectric body may also be used.

[0067] Furthermore, the specific configuration of the piezoelectric element 21, the shape of the flow path, and the configuration and positional relationship of various components including the manifold 40 and the nozzle plate 50 are not limited to the above example and can be changed as appropriate. Furthermore, the arrangement of the nozzles 51 and the pressure chambers 31 is not limited to the above example. For example, the nozzles 51 may be arranged in two or more rows. Furthermore, dummy chambers may be formed between multiple pressure chambers 31. Furthermore, although the example has been shown in which the piezoelectric element 21 has dummy layers 212 on both ends in the stacking direction, the present invention is not limited to this example. The piezoelectric element 21 may have a dummy layer 212 on only one side, or the piezoelectric element 21 may not have a dummy layer 212.

[0068] For example, the liquid to be ejected is not limited to ink for printing, but may be a device that ejects liquid containing conductive particles for forming a wiring pattern on a printed wiring board.

[0069] Furthermore, in the above embodiment, the inkjet head 1 is used in a liquid ejection device such as an inkjet recording device, but the invention is not limited to this and can also be used in, for example, 3D printers, industrial manufacturing machines, and medical applications, and can be made smaller, lighter, and less expensive.

[0070] According to at least one of the embodiments described above, it is possible to provide a piezoelectric actuator, a liquid ejection head, and a method for manufacturing a liquid ejection head that are less susceptible to power concentration.

[0071] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. The following is a description equivalent to the invention described in the claims of the original application. (1) an actuator section including a plurality of piezoelectric element rows, each row having a plurality of piezoelectric elements each having a plurality of piezoelectric bodies and an internal electrode, and each row having an inter-element groove formed between adjacent piezoelectric elements in an arrangement direction of the piezoelectric elements; a conductor portion including an electrode row, the conductor portion being provided in the inter-row grooves formed between the plurality of piezoelectric element rows, the conductor portion including a plurality of electrode elements made of a conductive material arranged in parallel in the row direction, and an inter-electrode groove being formed between the electrode elements adjacent in the row direction, the inter-electrode groove being continuous with the inter-element groove; A piezoelectric actuator comprising: (2) a base for holding a plurality of the piezoelectric element rows; the inter-column groove is deeper than the inter-element groove and is formed to reach the base; The piezoelectric actuator according to (1), wherein the base has, at least in part, a conductive portion that forms part of the inter-row groove and is connected to the conductor portion in the inter-row groove. (3) The piezoelectric actuator according to (1) or (2), a vibration plate that vibrates due to vibration of the piezoelectric element; a plurality of pressure chambers facing the diaphragm; The conductor portion has a connecting portion that connects the plurality of electrode elements on the bottom side of the inter-element groove. (4) bonding a plurality of rows of piezoelectric members each having a plurality of piezoelectric layers and internal electrodes to a base; forming a conductor portion made of a conductive material in an inter-row groove formed between the plurality of rows of piezoelectric members; A method for manufacturing a liquid ejection head, comprising: forming a plurality of inter-element grooves in the conductor portion and the plurality of rows of the piezoelectric members to form a piezoelectric element row having a plurality of piezoelectric elements and an electrode row having a plurality of electrode elements, respectively. (5) bonding a piezoelectric member having a plurality of piezoelectric layers and internal electrodes to a base; forming inter-row grooves in the piezoelectric member to divide it into a plurality of rows; forming a conductor portion made of a conductive material in the inter-row groove; A method for manufacturing a liquid ejection head, comprising: forming a plurality of inter-element grooves in the conductor portion and the plurality of rows of the piezoelectric members to form a piezoelectric element row having a plurality of piezoelectric elements and an electrode row having a plurality of electrode elements, respectively. [Explanation of symbols]

[0072] 1...inkjet head, 2...piezoelectric actuator, 10...base, 20...actuator unit, 21...piezoelectric element, 22...inter-element groove, 25...inter-row groove, 211...piezoelectric layer, 212...dummy layer, 30...diaphragm, 31...pressure chamber, 40...manifold, 42...partition wall portion, 50...nozzle plate, 51...nozzle, 70...wiring board, 71...driving IC, 100...inkjet recording device, 111...casing, 112...medium supply portion, 113...image forming portion, 114...medium discharge portion, 115...conveyor Feed device, 116...control unit, 117...support unit, 118...conveyor belt, 119...support plate, 120...belt roller, 121...pair of guide plates, 122...conveyor roller, 130...head unit, 132...ink tank, 133...connecting flow path, 134...supply pump, 200...laminated piezoelectric member, 201, 202...piezoelectric element array, 221, 222...internal electrode, 224...external electrode, 227...conductor portion, 2270...electrode array, 2271...electrode element, 2272...connecting portion, 2273...inter-pole groove.

Claims

1. An actuator section including a plurality of piezoelectric element rows, each row having a plurality of stacked piezoelectric bodies and a plurality of internal electrodes, arranged side by side, and an inter-element groove formed between each of the piezoelectric elements adjacent to each other in the arrangement direction of the piezoelectric elements; a conductor section including an electrode row, the electrode elements being made of a conductive material and filled in the inter-row grooves formed between the plurality of piezoelectric element rows, and arranged in parallel in the arrangement direction, and an inter-electrode groove being formed between the electrode elements adjacent in the arrangement direction, the inter-electrode groove being continuous with the inter-element groove; Equipped with A piezoelectric actuator, wherein the plurality of electrode elements are connected to a plurality of internal electrodes within each piezoelectric element.

2. a base for holding a plurality of the piezoelectric element rows; the inter-column groove is deeper than the inter-element groove and is formed to reach the base; The piezoelectric actuator according to claim 1 , wherein the base has, at least in part, a conductive portion that forms part of the inter-row groove and is connected to the conductor portion in the inter-row groove.

3. The piezoelectric actuator according to claim 1 or 2; a vibration plate that vibrates due to vibration of the piezoelectric element; a plurality of pressure chambers facing the diaphragm; The conductor portion has a connecting portion that connects the plurality of electrode elements on the bottom side of the inter-element groove.

4. A method of bonding a piezoelectric member having a plurality of laminated piezoelectric layers and a plurality of internal electrodes to a base in multiple rows; filling inter-row grooves formed between the plurality of rows of piezoelectric members with a conductive material to form conductor portions made of the conductive material connected to the plurality of internal electrodes of the piezoelectric members; A method for manufacturing a liquid ejection head, comprising: forming a plurality of inter-element grooves in the conductor portion and the plurality of rows of the piezoelectric members to form a piezoelectric element row having a plurality of piezoelectric elements and an electrode row having a plurality of electrode elements, respectively.

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