Piezoelectric actuator and liquid ejection head

Abstract

To provide a piezoelectric actuator and a liquid discharge head capable of inspecting the performance of piezoelectric elements.SOLUTION: A piezoelectric actuator according to an embodiment of the present invention includes piezoelectric members and internal electrodes, and has an electrode layer formed on one side region in a first direction on one side surface and an electrode-removed portion with no electrode layer formed on the other side region. The piezoelectric actuator includes a plurality of first grooves, a plurality of first piezoelectric elements, a second piezoelectric element, a second groove, a connection element portion, discrete electrodes, and a connection electrode. The plurality of first grooves are formed in a region extending from one side in the first direction to the electrode-removed portion. The second groove is shallower than the first grooves and formed in a region not reaching the electrode-removed portion. A connection element portion is provided adjacent to the second piezoelectric element via the second groove. A connection electrode extends from the one side surface of the connection element portion to the other side of the second groove in the first direction and is connected to the discrete electrodes of the adjacent second piezoelectric element.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] An embodiment of the present invention relates to a piezoelectric actuator and a liquid ejection head. [Background technology]

[0002] Conventionally, piezoelectric actuators using piezoelectric materials such as PZT are used to drive inkjet heads, etc. In inkjet heads, actuators are arranged at very small intervals, and many heads have a structure in which many grooves are formed in one piezoelectric material and the divided pillar parts serve as one actuator.

[0003] In such a liquid ejection head, it is necessary to inspect the performance of the piezoelectric element. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-56730 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a piezoelectric actuator and a liquid ejection head that are capable of inspecting the performance of a piezoelectric element. [Means for solving the problem]

[0006] A piezoelectric actuator according to an embodiment has a piezoelectric member and an internal electrode, and an electrode layer is formed in an area on one side in a first direction on one side of one side, and an electrode removed portion where no electrode layer is formed is provided on the other side. The piezoelectric actuator includes a plurality of first grooves, a plurality of first and second piezoelectric elements, a second groove, a connection element portion, an individual electrode, and a connection electrode. The plurality of first grooves are formed in an area from one side in the first direction to the electrode removed portion. The plurality of first and second piezoelectric elements are arranged side by side via the first grooves. The second groove is shallower than the first groove and is formed in an area not reaching the electrode removed portion. The connection element portion is provided adjacent to the second piezoelectric element via the second groove. A plurality of individual electrodes are formed in an area on the one side of the bottom of the first groove in the first direction on one side of the plurality of first piezoelectric elements and the second piezoelectric elements, respectively. The connection electrode extends from one side surface of the connection element portion to the other side in the first direction beyond the second groove, and is connected to the individual electrode of the adjacent second piezoelectric element. The first groove and the second groove have a depth that reaches the other side in the first direction beyond the internal electrode, and the internal electrode is divided by the first groove and the second groove. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a cross-sectional view showing the configuration of a portion of the inkjet head according to the first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing a configuration of a portion of the inkjet head. [Diagram 3] FIG. 2 is a perspective view showing a configuration of a portion of the inkjet head. [Figure 4] FIG. 2 is a cross-sectional view showing the configuration of a piezoelectric actuator of the inkjet head. [Diagram 5] 5A to 5C are explanatory diagrams showing a method of manufacturing the piezoelectric actuator of the inkjet head. [Figure 6] FIG. 1 is an explanatory diagram showing a schematic configuration of an inkjet recording apparatus according to a first embodiment. [Figure 7] FIG. 11 is a side view showing the configuration of a piezoelectric actuator according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] An inkjet head 1, which is a liquid ejection head according to a first embodiment, a piezoelectric actuator 20, and an inkjet recording device 100, which is a liquid ejection device, will be described below with reference to Figs. 1 to 6. Figs. 1 and 2 are cross-sectional views showing a schematic configuration of a portion of the inkjet head 1, and Fig. 3 is a perspective view showing a schematic configuration of a portion of the inkjet head 1. Fig. 4 is a side view showing the configuration of the piezoelectric actuator of the inkjet head, and Fig. 5 is an explanatory diagram showing a manufacturing method of the piezoelectric actuator. Fig. 6 is an explanatory diagram showing a schematic configuration of the inkjet recording device 100. In the figure, arrows X, Y, and Z respectively indicate three directions that are orthogonal to each other. In each figure, the configuration is enlarged, reduced, or omitted as appropriate for the purpose of explanation.

[0009] 1 to 4, the inkjet head 1 includes a base 10, a piezoelectric actuator 20 having a plurality of first piezoelectric elements 231, a second piezoelectric element 232, and a connection element portion 233, a vibration plate 30, a manifold 40, a nozzle plate 50 which is a nozzle member having a plurality of nozzles 51, a frame 60, and an FPC 70. As an example, the inkjet head 1 is provided with several hundreds of nozzles 51 and pressure chambers 31 in the third direction, and is configured to have a length of several tens of mm in the third direction which is the longitudinal direction of the piezoelectric actuator 20.

[0010] The piezoelectric actuator 20 is constituted by a laminated piezoelectric element 201, and is disposed at one end of the base 10 in the first direction, for example, and joined to the base 10.

[0011] The piezoelectric actuator 20 includes piezoelectric layers 211, which are a plurality of piezoelectric members stacked along a first direction indicated by the Z direction in the drawing, a dummy layer 212, internal electrodes 221, 222 formed on the main surface of each piezoelectric layer 211, an external electrode 223 constituting an individual electrode 2231 and a connection electrode 2232, and an external electrode 224 constituting a common electrode 2241. Thus, as part of the piezoelectric actuator 20, the plurality of first piezoelectric elements 231 and the plurality of second piezoelectric elements 232 arranged in parallel via the grooves 22 each include a plurality of piezoelectric layers 211, dummy layers 212, the internal electrodes 221, 222, and the external electrodes 223, 224.

[0012] 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 in the thickness direction along the stacking direction, and are bonded to each other via an adhesive layer.

[0013] The internal electrodes 221 and 222 are conductive films formed into a predetermined shape using a conductive material that can be fired, such as silver palladium. The internal electrodes 221 and 222 are formed in a predetermined region on the main surface of each piezoelectric layer 211. The internal electrodes 221 and 222 have different polarities. For example, one internal electrode 221 is formed in a region that reaches one end of the piezoelectric layer 211 in a second direction shown as the Y direction in the figure, but does not reach the other end. The second direction is a direction perpendicular to the first direction, which is the lamination direction. The other internal electrode 222 is formed in a region that does not reach one end of the piezoelectric layer 211 in the second direction shown as the Y direction in the figure, but reaches the other end. The internal electrodes 221 and 222 are connected to the piezoelectric elements 231 and 232, and the external electrodes 223 and 224 formed on the side surfaces of the connection element portion 233, respectively. The piezoelectric actuator 20 is polarized during the manufacturing process.

[0014] The external electrodes 223 and 224 are formed on the side surfaces of the piezoelectric elements 231 and 232 and the connecting element portion 233, respectively, and are formed by gathering the ends of the internal electrodes 221 and 222 together.

[0015] The external electrodes 223 and 224 are formed by a known method such as plating or sputtering using Ni, Cr, Au, etc. The external electrodes 223 and 224 are, for example, different poles, and are disposed on different side surfaces. Alternatively, the external electrodes 223 and 224 may be disposed on different regions of the same side surface.

[0016] The dummy layer 212 is made of the same material as the piezoelectric layer 211. The dummy layer 212 has an electrode on only one side, and is not subjected to an electric field, so it does not deform. In other words, the dummy layer 212 does not function as a piezoelectric body, but serves as a base for fixing the piezoelectric actuator 20 to the base 10, or serves as a polishing allowance for polishing to achieve precision during and after assembly.

[0017] In the piezoelectric actuator 20, an electrode removal portion 27 is formed at the end of the base portion 26 side on the side where the individual electrodes are arranged. For example, the electrode removal portion 27 is a chamfered portion 29 in which the end face on the side where the individual electrodes are arranged is tapered so as to retreat in a direction away from the FPC 70 toward the base 10 side, and extends in a surface direction along the first direction which is the stacking direction and the third direction which is the arrangement direction of the pressure chambers. For example, the electrode removal portion 27 is provided in a dummy layer 212 in which the common internal electrodes 221, 222 are not stacked in the first direction. That is, a portion of the piezoelectric member that does not function as a piezoelectric body and does not deform is partially cut out. The electrode removal portion 27 is arranged at a position avoiding the internal electrodes 221, 222 and the external electrodes 223, 224.

[0018] The piezoelectric actuator 20 is divided into multiple parts on one side by a plurality of first grooves 22 and second grooves 24, and integrally comprises a plurality of first piezoelectric elements 231 lined up on either side of the first groove 22 and a second piezoelectric element 232 provided at the end of the element row of the piezoelectric elements 231, a connection element portion 233 lined up to the second piezoelectric element 232 via the second groove 24, and a base portion 26.

[0019] That is, the piezoelectric actuator 20 has a comb-like shape in which one end is divided into a plurality of pieces by forming grooves 22, 24 by, for example, dicing, and the other end is connected. First piezoelectric elements 231 are arranged alternately in parallel with grooves 22 in between along a third direction indicated by X in the figure. Then, a connection element portion 233 is arranged adjacent to a second piezoelectric element 232 arranged at an end of the row of first piezoelectric elements 231, with a groove 24 shallower than the groove 22 interposed therebetween. The second piezoelectric element 232 is the piezoelectric element to be measured to which electricity is applied during measurement.

[0020] A plurality of first grooves 22 are arranged in the third direction. For example, the plurality of grooves 22 are arranged at equal intervals at a predetermined pitch in the third direction. The first grooves 22 are slits that open on one side and have a predetermined depth that reaches an electrode removal portion 27 described below, and extend over the entire length of the piezoelectric actuator 20 in the second direction, dividing the piezoelectric actuator 20 into a plurality of columnar first piezoelectric elements 231 and second piezoelectric elements 232 at the end portions.

[0021] External electrodes 223, 224 connected to the internal electrode 22 are formed on the side surfaces of the first piezoelectric element 231 and the second piezoelectric element 232, respectively. For example, the external electrodes 223 and 224 have different polarities, and are disposed on different side surface portions. Alternatively, the external electrodes 223 and 224 may be disposed in different regions of the same side surface portion.

[0022] As an example, in this embodiment, external electrodes 223 constituting individual electrodes are formed on one side surfaces of the first piezoelectric elements 231 and the second piezoelectric elements 232, and external electrodes 224 constituting the common electrode 2241 are formed on the other side surfaces. In other words, the external electrodes 223 serving as individual electrodes are disposed in regions on one side surfaces of the plurality of first piezoelectric elements 231 and second piezoelectric elements 232 on one side of the bottoms of the first grooves 22 in the first direction. The external electrodes 223 are separated from each other by the first grooves 22.

[0023] For example, the multiple first piezoelectric elements 231 and second piezoelectric elements 232 have the same width dimension. Half of the first piezoelectric elements 231 are arranged so that every other one faces the pressure chamber 31 via the vibration plate 30, and the remaining half are arranged so that they face the partition wall portion 42. The second piezoelectric element 232 has the same layered structure as the first piezoelectric element 231, and at least the columnar effective portion on which the internal electrodes 221, 222 are formed is configured to have the same shape and dimensions as the first piezoelectric element 231.

[0024] At least a part of the first piezoelectric elements 231 constitutes an actuator driven by application of an electrode voltage. For example, half of the first piezoelectric elements 231 facing the pressure chambers 31 among the plurality of first piezoelectric elements 231 become actuators driven by application of a voltage, and the remaining half of the first piezoelectric elements 231 facing the partition wall portion 42 are not driven or are auxiliarily driven by application of a predetermined voltage.

[0025] The first driving piezoelectric element 231, which serves as an actuator, vibrates longitudinally along the stacking direction of the piezoelectric layer 211 when a voltage is applied to the internal electrodes 221, 222 via the external electrodes 223, 224. For example, the longitudinal vibration referred to here is "vibration in the thickness direction defined by the piezoelectric constant d33." Note that in this embodiment, as an example, as shown in FIG. 2, a plurality of alternate driving first piezoelectric elements 231 are arranged corresponding to the pressure chambers 31 across the vibration plate 30, and the remaining first piezoelectric elements 231 are arranged in positions facing the partition wall 42 across the vibration plate 30.

[0026] The second groove 24 is arranged in line at the end of the row of the first grooves 22. For example, the second groove 24 is shallower than the first groove 22, and is configured to have a depth dimension that does not reach the electrode removal portion 27 described later. That is, the second piezoelectric element 232 for measurement and the connection element portion 233 for current flow, which are arranged on one side and the other side of the second groove 24, are connected at the side portion of the base portion 26, which is the region on the other side of the bottom of the groove 22. As an example, the second groove 24 is formed at a position deeper than the region where the internal electrodes 221, 222 are formed, that is, on the other side in the first direction. That is, the bottom of the second groove 24 is arranged at a position deeper than the region where the internal electrodes 221, 222 are formed, that is, on the other side in the first direction.

[0027] The connection element portion 233 is configured in a wall or column shape. The region of the connection element portion 233 adjacent to the second piezoelectric element 232 for measurement has the same laminated structure as the first piezoelectric element 231 and the second piezoelectric element 232, and is configured to have a width dimension in the third direction larger than the first piezoelectric element 231 and the second piezoelectric element 232. The connection element portion 233 is provided adjacent to the second piezoelectric element 232 for measurement that is to be measured, and has a connection electrode 2232 that is conductive to the individual electrode 2231 of the second piezoelectric element 232.

[0028] For example, the width dimension of the connection element portion 233 in the third direction is several tens of times that of the first piezoelectric element 231 and the second piezoelectric element 232. The connection element portion 233 is disposed adjacent to the second piezoelectric element 232 at the end of the row of the first piezoelectric element 231 via the second groove 24, for example. External electrodes 223 and 224 connected to the internal electrodes 221 and 222 are formed on the side surface of the connection element portion 233. For example, the external electrode 223 and the external electrode 224 are different polarities, and the external electrode 223 and the external electrode 224 are disposed on different side surfaces. Alternatively, the external electrodes 223 and 224 may be arranged in different regions of the same side surface.

[0029] On one side of the connection element portion 233, an external electrode 224 constituting a part of the common electrode 2241 is formed in an end region, and an external electrode 223 constituting the connection electrode 2232 is formed in a region on the second piezoelectric element 232 side, and an insulating layer 225 is formed between adjacent external electrodes 223 and 224. The external electrode 223 is formed from one side of the connection element portion 233 to one side of the adjacent second piezoelectric element 232, passing through a region of the base portion 26 that is on the other side of the second groove 24 in the first direction. That is, the individual electrode 2231 of the second piezoelectric element 232 arranged at the end of the piezoelectric actuator 20 and the connection electrode 2232 of the connection element portion 233 are formed to be integrally connected.

[0030] An external electrode 224 constituting a common electrode 2241 is formed on the other side surface and the end surface in the parallel direction of the connection element portion 233. That is, the external electrode 224 passes through an end surface portion 251 of the connection element portion 233 and is led out to an adjacent region on the same side surface as the surface on which the external electrode 223 is formed.

[0031] One side surface of the connection element portion 233 configured in this manner is formed wider than the first piezoelectric element 231 and the second piezoelectric element 232. The external electrode 223 formed on one side surface of the connection element portion 233 constitutes a current-carrying terminal 2233 for an individual electrode. Furthermore, the external electrode 224 formed on the side surface of the connection element portion 233 constitutes a current-carrying terminal 2243 for a common electrode 2241. In other words, the connection element portion 233 has current-carrying terminals 2233, 2243 for measurement, and is configured to be able to conduct electricity by applying a probe or the like to one side surface of the connection element portion 233.

[0032] Base portion 26 extends in the third direction, and connects the plurality of first piezoelectric elements 231, second piezoelectric elements 232, and connection element portion 233 on the bottom side of first groove 22 and second groove 24. For example, one side of base portion 26 has electrode removed portion 27 where no electrode is formed, and the other side has a part of common electrode 2241 formed thereon.

[0033] In this embodiment, as an example, the external electrode 223 is an individual electrode, and the external electrode 224 is a common electrode 2241. The external electrodes 223 constituting the individual electrodes 2231 of the multiple first piezoelectric elements 231 are arranged independently by dividing the electrode layer by the groove 22. The external electrodes 224 constituting the common electrode 2241 are connected to each other in an area of ​​the electrode layer closer to the base 10 than the groove 22, and are, for example, grounded. That is, the common electrode 2241 is formed on the other side surfaces of the first piezoelectric element 231, the second piezoelectric element 232, and the connection element portion 233 that are spaced apart from each other, and is connected to the side surface of the base portion 26 on the other side than the bottom of the groove 22, and is formed integrally.

[0034] The external electrodes 223 serving as the individual electrodes 2231 provided on the first piezoelectric element 231 to be driven are connected to, for example, the FPC 70, and are connected to mounted components such as a driving IC via various wirings.

[0035] For example, each of the external electrodes 223, 224 is connected to a driving circuit 1161 of the control unit 116 as a driving unit via a driving IC by wiring, and is configured to be drive-controllable under control of a CPU (Central Processing Unit).

[0036] As an example, each of the first piezoelectric element 231 and the second piezoelectric element 232 has 50 or less laminated 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 laminated layers is less than 1000 μm.

[0037] The vibration plate 30 has a plate portion 301 that is arranged along a first direction, which is the stacking direction, for example, the thickness direction, and extends in a planar direction perpendicular to the first direction. The vibration plate 30 is bonded to one side of the stacking direction of the multiple first piezoelectric elements 231, i.e., the surface on the nozzle plate 50 side. The vibration plate 30 may have multiple protruding joints, for example, on the surface of the plate portion 301 that is configured to be deformable and that is bonded to the first piezoelectric element 231 of the piezoelectric actuator 20, and may be bonded to the piezoelectric element 23 at the joints.

[0038] The plate portion 301 is, for example, a metal plate, and has a plurality of vibration parts that face each pressure chamber 31 and can be displaced individually, and the plurality of vibration parts are integrally formed in a continuous manner. For example, the plate portion 301 is formed in the shape of a single flat plate, and the regions bonded to each piezoelectric element 231 constitute vibration parts that displace individually. Note that the plate portion 301 may have folds or steps formed in the parts adjacent to the vibration parts or between adjacent vibration parts so that the plurality of vibration parts can be easily displaced. The vibration plate 30 is deformed by the extension and compression of the first piezoelectric element 231, which displaces the part arranged opposite the piezoelectric element 23.

[0039] The vibration plate 30 is bonded to an end surface on one side of the first piezoelectric element 231. As an example, in this embodiment, the regions at both ends in the second direction of the main surface of the vibration plate 30 on one side in the first direction are bonded to the manifold 40. In the center of the inkjet head 1 in the second direction, a pressure chamber 31 capable of accommodating ink and a guide flow path 34 are formed between the vibration plate 30 and the manifold 40. The main surface on the other side in the first direction of the vibration plate 30 has an area on one end side bonded to the first piezoelectric element 231, and a predetermined area on the other end side in the second direction bonded to the frame 60. A common chamber 32 capable of accommodating ink is formed between the main surface on the other side in the first direction of the vibration plate 30 and the frame 60. That is, one side of the vibration plate 30 faces the piezoelectric element 23, and the other side faces the pressure chamber 31, the partition wall 42, and the guide flow path 34.

[0040] The vibration plate 30 has an opening 33 that penetrates in the thickness direction and communicates between the pressure chamber 31 and the common chamber 32. The pressure chamber 31 is formed on one side of the vibration plate 30 in the first direction, and the common chamber 32 is formed on the other side of the vibration plate 30 in the first direction. The common chamber 32 extends in the third direction and communicates with the multiple pressure chambers 31 lined up in the third direction. The vibration plate 30 changes its volume in response to the deformation of the piezoelectric element 23.

[0041] The manifold 40 is joined to one side of the vibration plate 30. The manifold 40 is disposed between the nozzle plate 50 and the vibration plate 30, and has a predetermined ink flow path 35 formed therein, the predetermined ink flow path 35 having a plurality of pressure chambers 31 separated by partition walls 42, and guide flow paths 34 extending in the second direction from the plurality of pressure chambers 31 toward the opening 33 and separated by the partition walls 42. The manifold 40 includes a frame-shaped portion 41 joined to the outer edge of the vibration plate 30, a plurality of partition walls 42 separating the plurality of ink flow paths 35, and a guide wall 43 forming the guide flow paths 34.

[0042] Moreover, the multiple pressure chambers 31 arranged in parallel in the third direction are separated by partition walls 42. That is, both sides of the pressure chambers 31 in the third direction are formed by the partition walls 42. Each pressure chamber 31 communicates with a nozzle 51 formed in a nozzle plate 50 disposed on one side in the first direction. Moreover, the pressure chamber 31 is closed on the side opposite the nozzle plate 50 by the vibration plate 30.

[0043] The multiple pressure chambers 31 communicate with the common chamber 32 via the guide flow paths 34 and the openings 33. The pressure chambers 31 hold liquid supplied from the common chamber 32 via the guide flow paths 34, and are deformed by vibration of the vibration plate 30 that forms a part of the pressure chambers 31, thereby ejecting the liquid from the nozzles 51.

[0044] The partition portion 42 is a wall member that separates the multiple pressure chambers 31 aligned in the third direction and also separates the multiple guide channels 34 aligned in the third direction 2, and constitutes both side portions of the pressure chambers 31 and the guide channels 34. The partition portion 42 is disposed opposite the first piezoelectric element 231 with the vibration plate 30 interposed therebetween, and is supported by the first piezoelectric element 231.

[0045] 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 / 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 is formed with a plurality of nozzles 51 penetrating 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 each of the pressure chambers 31.

[0046] The frame 60 is disposed on the other side in the first direction of the vibration plate 30. The frame 60 forms a common chamber 32 between itself and the vibration plate 30. The common chamber 32 is formed inside the frame 60, and communicates with the pressure chamber 31 through an opening 33 and a guide flow path 34 provided in the vibration plate 30.

[0047] The FPC 70 is connected to the individual electrodes 2231. The FPC 70 includes a base layer, an electrode layer, a solder plating layer, an adhesive layer, and an insulating cover layer.

[0048] The FPC 70 is electrically and mechanically connected to the external electrode 223 by aligning the area where the solder-plated layer is formed opposite the bonding surface of the first piezoelectric element 231 and heating it to melt the solder in the solder-plated layer.

[0049] In the inkjet head 1 configured as above, the nozzle plate 50, the frame 60, the manifold 40, and the vibration plate 30 form an ink flow path 35 having a plurality of pressure chambers 31 communicating with the nozzles 51, a plurality of guide flow paths 34, and a common chamber 32 communicating with the plurality of pressure chambers 31. For example, the common chamber 32 communicates with a cartridge, and ink is supplied to each pressure chamber 31 through the common chamber 32. All the piezoelectric elements 23 are connected by wiring so that a voltage can be applied. In the inkjet head 1, when the control unit 116 applies a driving voltage to the internal electrodes 221 and 222 by the driving IC 1161, the first piezoelectric element 231 vibrates in the stacking direction, that is, in the thickness direction of each piezoelectric layer 211. In other words, the first piezoelectric element 231 vibrates vertically.

[0050] Specifically, the control unit 116 applies a driving voltage to the internal electrodes 221, 222 of the first piezoelectric element 231 to be driven, selectively driving the first piezoelectric element 231 to be driven. Then, the vibration plate 30 is deformed by combining the tensile deformation and the compressive deformation caused by the first piezoelectric element 231 to be driven, and the volume of the pressure chamber 31 is changed, so that liquid is guided from the common chamber 32 and ejected from the nozzle 51.

[0051] In the process of manufacturing the inkjet head 1 according to this embodiment, the internal electrodes 221, 222 are printed on a sheet-shaped piezoelectric material to form a piezoelectric layer 211 on which the internal electrodes 221, 222 are formed. Then, a plurality of piezoelectric layers 211 having the internal electrodes 221, 222 are stacked in a first direction and fired to form a laminated piezoelectric body 201. As shown in FIG. 5, external electrodes 223, 224 are formed on one and the other end faces in the second direction of the laminated piezoelectric body 201 by a printing process. Then, an electrode removal portion 27 is formed by chamfering one end portion on which the external electrode 223, which becomes the individual electrode 2231 and the connection electrode 2232, is disposed, by a dicing process. By forming the electrode removal portion 27, the electrode layer of the portion of the external electrode 223 on the base 10 side is removed. Furthermore, by forming a plurality of grooves 22 whose depth reaches the portion where the electrode has been removed by electrode removal portion 27, one side of laminated piezoelectric body 201 is divided into a plurality of portions to form a plurality of piezoelectric elements 21, and by forming grooves 24 that are shallower than the portion where the electrode has been removed by electrode removal portion, a second piezoelectric element 232 for measurement that is electrically connected to connection element portion 233 is formed. Note that the width of groove 24 for forming second piezoelectric element 232 for measurement may be set to be the same as the width of groove 22 for forming first piezoelectric element 231 for driving, and may be formed in the same processing step.

[0052] In this manner, piezoelectric actuator 20 is formed, one end of which is divided into a plurality of pieces and the other end of which is connected. Here, by making first groove 22 deep enough to reach electrode removal portion 27, the electrode layers on the side where electrode removal portion 27 is arranged become separate, independent individual electrodes 2231. Meanwhile, the electrode layers on the side where electrode removal portion 27 is not formed form common electrode 2241 that is continuous in the region closer to base portion 26 than the bottom of the groove.

[0053] Furthermore, the common electrode 2241 passes through the end face in the second direction and is drawn out to one side face. In this way, the individual electrodes 2231 of the second piezoelectric elements 232 at the end, the connection electrodes 2232 connected to the individual electrodes 2231, and the common electrode 2241 are formed side by side on the same surface.

[0054] Furthermore, the piezoelectric elements 231, 232 are polarized and attached to the base 10 with an adhesive or the like. Then, the FPC 70 is joined to the external electrode 223 which becomes the individual electrode 2231, the manifold 40 and the frame 60 are joined, the nozzles 51 are arranged opposite each pressure chamber 31, and the nozzle plate 50 is adhered, and the inkjet head 1 is completed.

[0055] An example of an inkjet recording device 100 including the inkjet head 1 will be described below with reference to Fig. 7. The inkjet recording device 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.

[0056] The inkjet recording device 100 is a liquid ejection device that performs an image formation process on paper P by ejecting liquid such as ink while transporting the paper P as a printing medium, which is the ejection target, along a predetermined transport path A from a medium supply section 112 through an image forming section 113 to a medium ejection section 114.

[0057] 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.

[0058] The medium supply unit 112 includes a plurality of paper feed cassettes, and is configured to be able to hold a plurality of sheets of paper P of various sizes in a stack.

[0059] The medium discharge unit 114 includes a paper discharge tray configured to be able to hold the paper P discharged from the discharge opening.

[0060] 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 so as to face the support section 117.

[0061] The support section 117 includes a conveyor belt 118 that is provided in a loop shape 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.

[0062] During image formation, the support section 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 feeding the conveyor belt 118 at a predetermined timing by the rotation of the belt roller 120.

[0063] The head unit 130 includes multiple (four colors) 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.

[0064] In this embodiment, the inkjet heads 1 are provided with four colors, cyan, magenta, yellow, and black, and ink tanks 132 that respectively contain ink of each color. The ink tanks 132 are connected to the inkjet heads 1 by connection channels 133.

[0065] In addition, a negative pressure control device such as a pump (not shown) is connected to the ink tank 132. Then, by controlling the negative pressure inside the ink tank 132 by the negative pressure control device according to the water head value between the inkjet head 1 and the ink tank 132, the ink supplied to each nozzle 51 of the inkjet head 1 is caused to form a meniscus of a predetermined shape.

[0066] The supply pump 134 is a liquid delivery pump constituted by, for example, a piezoelectric pump. The supply pump 134 is provided in a 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.

[0067] The conveying device 115 conveys the paper P along a conveying path A that extends 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.

[0068] Each of the guide plate pairs 121 includes a pair of plate members disposed opposite each other with the paper P being transported therebetween, and guides the paper P along the transport path A.

[0069] 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 disposed at various points along the conveying path A.

[0070] The control unit 116 includes a control circuit such as a CPU which serves as a controller, a ROM (Read Only Memory) which stores various programs, a RAM (Random Access Memory) which temporarily stores various variable data, image data, etc., and an interface unit which inputs data from the outside and outputs data to the outside.

[0071] In the inkjet recording device 100 configured as above, when the control unit 116 detects a print instruction by a user operating the operation input unit, for example, in an interface, the control unit 116 drives the conveying device 115 to convey the paper P and outputs a print signal to the head unit 130 at a predetermined timing, thereby driving the inkjet head 1. As a discharge operation, the inkjet head 1 sends a drive signal to the drive IC by an image signal corresponding to image data, applies a drive voltage to the internal electrodes 221 and 222, and selectively drives the first piezoelectric element 231 to be discharged, causing it to vibrate vertically in the stacking direction, and changes the volume of the pressure chamber 31 to discharge ink from the nozzle 51, thereby forming an image on the paper P held on the conveying belt 118. As a liquid discharge operation, the control unit 116 drives the supply pump 134 to supply ink from the ink tank 132 to the common chamber 32 of the inkjet head 1.

[0072] Here, the driving operation for driving the inkjet head 1 will be described. The inkjet head 1 according to this embodiment includes first piezoelectric elements 231 arranged opposite to the pressure chambers 31, and these first piezoelectric elements 231 are connected by wiring so that a voltage can be applied thereto. The control unit 116 sends a driving signal to the driving IC by an image signal corresponding to image data, applies a driving voltage to the internal electrodes 221 and 222 of the first piezoelectric element 231 to be driven, and selectively deforms the first piezoelectric element 231 to be driven, thereby deforming the vibration plate 30. Then, the volume of the pressure chamber 31 is changed by combining the deformation in the tensile direction and the deformation in the compressive direction of the vibration plate 30, thereby discharging the liquid. For example, the control unit 116 changes the volume of the pressure chamber 31 by alternately performing a pulling operation and a compressive operation.

[0073] In the inkjet head 1 and inkjet recording device 100 according to the above-mentioned embodiment, the second piezoelectric element 232 is formed at the end of the row of the first piezoelectric elements 231 constituting the actuator, and the connection element portion 233 serving as a current-carrying portion adjacent to the second piezoelectric element 232 via the second groove 24 is further formed to enable current to flow, so that the displacement of the second piezoelectric element 232 when a voltage is applied can be accurately measured after groove processing and before mounting of an FPC or the like. Therefore, it is possible to check whether the actuator member constituting the piezoelectric actuator 20 is normally polarized after groove processing and before mounting. That is, since current can be passed from the connection element portion 233 without mounting fine wiring or an FPC, the displacement of the top surface of the second piezoelectric element 232 for measurement when current is passed can be measured by a laser Doppler vibrometer or the like, and the driving performance of the piezoelectric element 231 can be measured. Note that, for example, a large piezoelectric member that generally corresponds to several hundred or more pressure chambers and has a length of several tens of mm or more has a large electrostatic capacitance and the waveform is dulled, making it difficult to accurately measure the deformation of the actuator. On the other hand, after groove processing and division into fine columnar members, the wiring is fine, and it is difficult to conduct electricity unless an FPC or the like is mounted. Furthermore, if a measurement is performed after processing and mounting of an FPC or the like and a defect is found, the mounted components such as the FPC and the current-carrying circuit will be discarded. In contrast, according to the above embodiment, by providing a second piezoelectric element 232 for measurement having a laminated structure similar to that of the first piezoelectric element 231 and a terminal connection element portion 233 constituting a current-carrying terminal at the end of the row of the first piezoelectric element 231, it is possible to conduct electricity to the second piezoelectric element 232 before mounting, and accurate measurement is possible. For example, if the displacement is within the allowable range, the next process is carried out, and even if a defect is found, it is not necessary to discard the expensive FPC or the driving circuit.

[0074] Further, according to the above embodiment, by simply forming the second groove 24 at the end of the column of the first piezoelectric element 231, the second piezoelectric element 232 for measurement can be easily formed. Further, the second groove 24 for forming the second piezoelectric element 232 for measurement is formed deeper than the region where the internal electrodes 221 and 222 are formed in the stacking direction, so that measurement equivalent to the displacement of the actual actuator is possible. At this time, if the width of the second groove 24 for forming the second piezoelectric element 232 for measurement is made the same as the width of the first groove 22 for forming the piezoelectric element 231 for driving, it can be formed by processing in the same process.

[0075] Note that the present invention is not limited to the above embodiment as it is, and at the implementation stage, the components can be deformed and embodied without departing from the gist thereof.

[0076] For example, the second piezoelectric element 232 for measurement may be provided at both ends of the element row of the first piezoelectric element 231, or may be provided only on one side. Although an example in which there is one second piezoelectric element 232 for measurement has been shown, the present invention is not limited thereto. For example, as another embodiment, a configuration including a plurality of second piezoelectric elements 232 for measurement may be used as in the piezoelectric actuator 200 shown in FIG. 7. For example, the piezoelectric actuator 200 has a plurality of second grooves 24 and a plurality of second piezoelectric elements 232, respectively. The plurality of second piezoelectric elements 232 are divided from each other by a plurality of second grooves 24 shallower than the electrode removal portion 27, and the individual electrodes 2231 are connected to each other. Therefore, these plurality of second piezoelectric elements 232 move in the same manner during measurement. Further, for example, when there is an internal electrode in the connection element portion 233, the connection element portion 233 also displaces simultaneously with the second piezoelectric element 232 during measurement. Note that these second piezoelectric elements 232 for measurement are not driven during printing. For example, when the piezoelectric elements 232 for measurement and the connection element portions 233 are arranged at both ends respectively, the characteristics of a wide range of the piezoelectric element 231 can be grasped. On the other hand, if the number of the piezoelectric elements 232 for measurement is increased, measurement variations and the like can be reduced. The second piezoelectric element 232 for measurement is not limited to having the same shape and size as the first piezoelectric element 231. For example, even if the shapes and sizes are different, the operation of the first piezoelectric element 231 for driving can be confirmed by inferring the operation of the second piezoelectric element 232 for measurement from the operation of the first piezoelectric element 231 for driving. In addition, although a configuration in which the external electrodes 223, 224 are formed on all of the plurality of columnar first piezoelectric elements 231 has been exemplified, the present invention is not limited to this, and there may be a first piezoelectric element 231 that is not formed with the external electrodes 223, 224. For example, an individual electrode or a common electrode may be formed on every other element or every few elements of the plurality of parallel first piezoelectric elements 231. In addition, the second piezoelectric element 232 for measurement and the connection element portion 233 may be configured to face or be joined to a peripheral member such as the frame 60. In the above embodiment, the connection element portion 233 having a laminated structure similar to that of the first piezoelectric element 231 and the second piezoelectric element 232 has been exemplified as the connection element portion 233 having the terminal for energizing, but the present invention is not limited to this. For example, the internal electrodes 221, 222 may not be formed on the connection element portion 233.

[0077] In the above embodiment, a plurality of piezoelectric layers are laminated, and the piezoelectric element 23 is driven by longitudinal vibration (d33) in the lamination direction, but the present invention is not limited to this. For example, the present invention is also applicable to a configuration in which the piezoelectric element 23 is composed of a single layer of piezoelectric material.

[0078] In addition, the specific configuration of the piezoelectric element 23, the shape of the flow path, and the configuration and positional relationship of various parts including the manifold 40, the nozzle plate 50, and the frame 60 are not limited to the above example, and can be changed as appropriate. In addition, 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. In addition, although an example has been shown in which the piezoelectric element 23 has the dummy layer 212 on both ends in the stacking direction, the present invention is not limited to this example. The piezoelectric element 23 may have the dummy layer 212 on only one side, or the first piezoelectric element 231 may have no dummy layer 212.

[0079] Furthermore, the liquid to be ejected is not limited to ink for printing, but may be, for example, a device that ejects liquid containing conductive particles for forming a wiring pattern on a printed wiring board.

[0080] In addition, in the above embodiment, the inkjet head 1 is used in a liquid ejection device such as an inkjet recording device, but the present invention is not limited to this and can also be used in, for example, 3D printers, industrial manufacturing machines, and medical applications, enabling reduction in size, weight, and cost.

[0081] According to at least one of the embodiments described above, it is possible to provide a liquid ejection head and a liquid ejection apparatus that can ensure liquid ejection performance with a small driving voltage.

[0082] Although several other 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 implemented 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 in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. The following is a description equivalent to the invention described in the claims of the original application. (1) a piezoelectric member and an internal electrode, an electrode layer is formed in one region on one side in a first direction on one side of the one surface, and an electrode removed portion is provided on the other side where the electrode layer is not formed; a plurality of first grooves formed in a region extending from one side in the first direction to the electrode removal portion; a plurality of first piezoelectric elements and a plurality of second piezoelectric elements arranged side by side via the first grooves; a second groove that is shallower than the first groove and does not reach the electrode removal portion; a connection element portion provided adjacent to the second piezoelectric element via the second groove; a plurality of individual electrodes formed in a region on the one side of a bottom of the first groove in the first direction on one side surfaces of the plurality of first piezoelectric elements and the second piezoelectric element; a connection electrode extending from one side surface of the connection element portion to the other side of the second groove in the first direction and connected to the individual electrode of the adjacent second piezoelectric element; A piezoelectric actuator comprising: (2) a base portion that connects the first piezoelectric elements, the second piezoelectric elements, and the connection element portion at bottom sides of the first groove and the second groove; a common electrode formed in a region extending from a bottom of the first groove to the other side in the first direction on the other side surfaces of the plurality of first piezoelectric elements, the second piezoelectric elements, and the connection element portion, the common electrode is connected to the base portion on the other side of the plurality of first piezoelectric elements, the second piezoelectric elements, and the connection element portion, the other side of the base portion being closer to the other side in the first direction than a bottom of the first groove; The first piezoelectric element and the second piezoelectric element each have a plurality of laminated piezoelectric layers and internal electrodes, The piezoelectric actuator of (1), wherein the first groove and the second groove have a depth extending beyond the internal electrode to the other side in the first direction, and the internal electrode is divided by the first groove and the second groove. (3) The piezoelectric actuator according to (2), wherein the common electrode extends from the other side surface to the one side surface. (4) the connection element portion has a width dimension larger than the width dimension of the first piezoelectric elements and the width dimension of the second piezoelectric elements in an arrangement direction of the first piezoelectric elements; The piezoelectric actuator according to any one of (1) to (3), wherein the first groove and the second groove have the same width dimension in the arrangement direction. (5) A piezoelectric actuator according to any one of (1) to (4); a pressure chamber whose volume changes due to vibration of the first piezoelectric element; a nozzle member that communicates with the pressure chamber and has a nozzle that ejects liquid in response to a change in volume of the pressure chamber; A liquid ejection head comprising: [Explanation of symbols]

[0083] 1...inkjet head, 10...base, 20...piezoelectric actuator, 22...first groove, 231...first piezoelectric element, 232...second piezoelectric element, 233...connection element portion, 24...second groove, 26...base portion, 27...electrode removal portion, 30...diaphragm, 31...pressure chamber, 32...common chamber, 33...opening, 34...guide flow path, 35...ink flow path, 40...manifold, 41...frame portion, 42...partition wall portion, 43...guide wall, 50...nozzle plate, 51...nozzle, 60...frame, 70...wiring board, 100...inkjet Recording device, 111...housing, 112...medium supply section, 113...image forming section, 114...medium discharge section, 115...conveying device, 116...control section, 117...support section, 118...conveying belt, 119...support plate, 120...belt roller, 121...pair of guide plates, 122...conveying roller, 130...head unit, 132...ink tank, 133...connecting flow path, 134...supply pump, 201...laminated piezoelectric element, 221, 222...internal electrodes, 223, 224...external electrodes, 2231...individual electrodes, 2232...connecting electrodes.

Claims

1. a piezoelectric member and an internal electrode, an electrode layer is formed in an area on one side in a first direction on one side of the one surface, and an electrode removed portion is provided on the other side where no electrode layer is formed; a plurality of first grooves formed in a region extending from one side in the first direction to the electrode removal portion; a plurality of first piezoelectric elements and a plurality of second piezoelectric elements arranged side by side via the first grooves; a second groove that is shallower than the first groove and does not reach the electrode removal portion; a connection element portion provided adjacent to the second piezoelectric element via the second groove; a plurality of individual electrodes formed in a region on one side of a plurality of the first piezoelectric elements and a plurality of the second piezoelectric elements on the one side of a bottom of the first groove in the first direction; a connection electrode extending from one side surface of the connection element portion to the other side of the second groove in the first direction and connected to the individual electrode of the adjacent second piezoelectric element; Equipped with A piezoelectric actuator, wherein the first groove and the second groove have a depth that reaches the other side in the first direction beyond the internal electrode, and the internal electrode is divided by the first groove and the second groove.

2. a base portion connecting the first piezoelectric elements, the second piezoelectric elements, and the connection element portion at bottom sides of the first groove and the second groove; a common electrode formed in a region extending from a bottom of the first groove to the other side in the first direction on the other side surfaces of the plurality of first piezoelectric elements, the second piezoelectric elements, and the connection element portion, the common electrode is connected to the base portion on the other side of the plurality of first piezoelectric elements, the second piezoelectric elements, and the connection element portion, the other side of the base portion being closer to the other side in the first direction than a bottom of the first groove; The piezoelectric actuator according to claim 1 , wherein the first piezoelectric element and the second piezoelectric element each have a plurality of laminated piezoelectric layers and internal electrodes.

3. The piezoelectric actuator according to claim 2 , wherein the common electrode extends from the other side surface to the one side surface.

4. the connection element portion has a width dimension larger than the first piezoelectric elements and the second piezoelectric elements in an arrangement direction of the first piezoelectric elements, 4. The piezoelectric actuator according to claim 1, wherein the first groove and the second groove have the same width in the arrangement direction.

5. A piezoelectric actuator according to any one of claims 1 to 4, a pressure chamber whose volume changes due to vibration of the first piezoelectric element; a nozzle member that communicates with the pressure chamber and has a nozzle that ejects liquid in response to a change in volume of the pressure chamber; A liquid ejection head comprising:

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