Piezoelectric actuator and liquid discharge head

Abstract

To provide a piezoelectric actuator and a liquid discharge head that secure high positional accuracy.SOLUTION: A piezoelectric actuator is a laminated piezoelectric member in which a plurality of piezoelectric layers constituted of a piezoelectric material and a plurality of electrode layers are laminated. The piezoelectric actuator integrally comprises: a plurality of element parts that are divided by a plurality of grooves formed on one side in the lamination direction, and that are arrayed in a first direction; and a base part that is formed of a piezoelectric material, and that is arranged to be continuous with the other side in the lamination direction, of the plurality of element parts.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In a liquid ejection device such as an inkjet printer head, an actuator member using a piezoelectric material such as PZT is used as a drive source for the liquid ejection head. For example, the actuator member is configured by attaching a grooved actuator member to a base member.

[0003] High precision is required in bonding the actuator member to the base member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 5668382 Summary of the Invention [Problem to be solved by the invention]

[0005] The problem to be solved by the present invention is to provide a piezoelectric actuator and a liquid ejection head that can ensure high positional accuracy. [Means for solving the problem]

[0006] The piezoelectric actuator according to the embodiment is a laminated piezoelectric component in which a plurality of piezoelectric layers made of a piezoelectric material and a plurality of electrode layers are stacked, and integrally comprises a plurality of element portions separated by a plurality of grooves formed on one side of the stacking direction and aligned in a first direction, and a base portion formed of a piezoelectric material and arranged continuously with the plurality of element portions on the other side of the stacking direction. [Brief explanation of the drawings]

[0007] [Figure 1]FIG. 1 is a cross-sectional view showing the configuration of a portion of a liquid ejection head according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing a configuration of a part of the liquid ejection head. [Figure 3] 5A to 5C are explanatory diagrams showing a method for manufacturing the liquid ejection head. [Figure 4] 5A to 5C are explanatory diagrams showing a method for manufacturing the liquid ejection head. [Figure 5] FIG. 1 is an explanatory diagram showing a schematic configuration of a liquid ejection device according to a first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] A liquid ejection head 1 and a liquid ejection device 100 according to the first embodiment will be described below with reference to FIGS. 1 to 5. FIGS. 1 and 2 are cross-sectional views showing the configuration of a portion of the liquid ejection head according to the first embodiment. FIGS. 3 and 4 are explanatory diagrams showing a method for manufacturing a liquid ejection head. FIG. 5 is an explanatory diagram showing the schematic configuration of a liquid ejection device. In the figures, arrows X, Y, and Z indicate three mutually orthogonal directions. For the purpose of explanation, the configuration is enlarged, reduced, or omitted in each figure as appropriate.

[0009] As shown in Figures 1 and 2, the liquid ejection head 1 is an inkjet head that includes a piezoelectric actuator 10 (piezoelectric member) that has multiple actuator portions 11 and a base portion 12 integrated together, a flow path member 40, a nozzle plate 50 that has multiple nozzles 51, a frame portion 60 as a structural portion, and a drive circuit 70.

[0010] As an example, the liquid ejection head 1 includes two rows of actuator units 11, each of which has two rows of nozzle units 51 arranged in a row direction (X direction), two rows of pressure chamber units 31 arranged in the row direction, and two rows of element units 21, 22 (element units) arranged in the row direction. In this embodiment, an example is shown in which the stacking direction of the plurality of piezoelectric layers 211, the vibration direction of the piezoelectric elements 21, and the vibration direction of the vibration plate 30 are all along the Z direction.

[0011] The piezoelectric actuator 10 integrally comprises a pair of actuator parts 11 and a base part 12, and the two actuator parts 11 are arranged side by side in the Y direction on one side of the base part 12 in the Z direction, for example with a groove 25 interposed therebetween.

[0012] Each actuator section 11 includes a plurality of drive piezoelectric elements 21, which are arranged alternately along the direction and serve as actuators, and a plurality of non-drive piezoelectric elements 22. The actuator section 11 is a laminated piezoelectric member 201 in which a plurality of piezoelectric layers 211 and a plurality of internal electrodes 221, 222 (internal electrode layers) are laminated.

[0013] In the actuator section 11, the plurality of drive piezoelectric elements 21 and the plurality of non-drive piezoelectric elements 22 are arranged in one direction at regular intervals. For example, the plurality of piezoelectric elements 21, 22 are connected to each other by the base section 12.

[0014] As an example, the plurality of drive piezoelectric elements 21 and the plurality of non-drive piezoelectric elements 22 are each configured in the shape of a rectangular parallelepiped pillar with the same external shape. A plurality of grooves 23 are formed on one side of the actuator section 11, dividing one end side into a plurality of drive piezoelectric elements 21 and non-drive piezoelectric elements 22. The plurality of drive piezoelectric elements 21 and non-drive piezoelectric elements 22 are aligned in the column direction at the same pitch by grooves 23 of the same width in the alignment direction. Furthermore, since the depth of the grooves 23 of the actuator section 11 is set to be smaller than the overall length of the actuator section 11 in the Z direction, a base section 12 that integrally connects the plurality of elements 21, 22 is formed on the base end side from the bottom surfaces of the grooves 23.

[0015] Individual electrodes constituting the external electrode 223 are formed on one side surface of the actuator section 11, which is an end surface in the Y direction different from the Z direction. The individual electrodes are, for example, a plurality of line patterns spaced apart from one another on one side surface of the actuator section 11. In other words, on one side surface of the actuator section 11, external electrodes 223 each having a plurality of line patterns spaced apart from one another and electrode removal portions in which the electrode layer has been removed by PEP or the like are alternately formed.

[0016] One side surface constitutes a mounting portion where ACF mounting or solder mounting is performed. As an example, an FPC 71 is electrically and mechanically connected to the individual electrodes on one side surface of the actuator unit 11 by solder mounting or ACF mounting. For example, the side surface on which the mounting portion is formed and the other side surface on the opposite side form a surface perpendicular to the stacking direction.

[0017] Furthermore, a common electrode that constitutes the external electrode 224 is formed on the other side surface of the actuator element 11 in the Y direction. The common electrode is formed on the other side surface of the actuator element 11 by a continuous electrode layer.

[0018] For example, the multiple driving piezoelectric elements 21 and the multiple non-driving piezoelectric elements 22 are each configured in a rectangular shape when viewed in a plan view from the Z direction, with the short side direction aligned with the row direction of the element row and the long side direction aligned with the extension direction (second direction) perpendicular to the row direction and the Z direction.

[0019] The driving piezoelectric elements 21 are arranged in positions in the Z direction opposite the plurality of pressure chambers 31 formed in the flow path member 40. As an example, the center positions in the column direction and extension direction of the driving piezoelectric elements 21 and the center positions in the column direction and extension direction of the pressure chambers 31 are arranged side by side in the Z direction.

[0020] The non-driven piezoelectric elements 22 are arranged in positions in the Z direction facing the plurality of partition walls 42 formed in the flow path member 40. As an example, the center positions in the column direction and extension direction of the non-driven piezoelectric elements 22 and the center positions in the column direction and extension direction of the partition walls 42 are arranged side by side in the Z direction.

[0021] For example, the actuator section 11 is formed by dicing the laminated piezoelectric member 201 from one end face in the stacking direction to form grooves 23, thereby forming a plurality of rectangular pillar-shaped piezoelectric elements at predetermined intervals. Then, electrode layers are formed on the formed pillar-shaped elements, and a plurality of driving piezoelectric elements 21 and a plurality of non-driving piezoelectric elements 22 are formed, which are alternately arranged. The driving piezoelectric elements 21 and the non-driving piezoelectric elements 22 are alternately arranged in parallel in the column direction, with the grooves 23 sandwiched between them.

[0022] For example, the laminated piezoelectric member 201 that constitutes the actuator section 11 is formed by laminating sheet-shaped piezoelectric materials and electrode layers and sintering them.

[0023] The piezoelectric members constituting the driving piezoelectric element 21 and the non-driven piezoelectric element 22 are, for example, laminated piezoelectric members 201. The driving piezoelectric element 21 and the non-driven piezoelectric element 22 each include a plurality of laminated piezoelectric layers 211 and internal electrodes 221, 222 formed on the main surfaces of the piezoelectric layers 211. As an example, the driving piezoelectric element 21 and the non-driven piezoelectric element 22 have the same laminated structure. The driving piezoelectric element 21 and the non-driven piezoelectric element 22 each include external electrodes 223, 224 formed on the surfaces thereof.

[0024] The piezoelectric layer 211 is formed in the shape of a thin plate from, for example, a lead-free KNN (potassium sodium niobate) piezoelectric material. The lead-free piezoelectric material is a lead-free piezoelectric material. The multiple piezoelectric layers 211 are stacked with their thickness direction aligned with the stacking direction and are bonded to each other. For example, in this embodiment, the thickness direction and stacking direction of the piezoelectric layers 211 are arranged along the vibration direction (Z direction).

[0025] The internal electrodes 221, 222 are conductive films formed into a predetermined shape using a sinterable conductive material such as silver-palladium. The internal electrodes 221, 222 are formed in predetermined regions on the main surface of each piezoelectric layer 211. The internal electrodes 221, 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 of the piezoelectric layer 211 in the extension direction (Y direction), which is a direction perpendicular to both the row direction (X direction) in which the multiple drive piezoelectric elements 21 and the multiple non-drive piezoelectric elements 22 are arranged and the vibration direction (Z 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 of the piezoelectric layer 211 in the extension direction. The internal electrodes 221, 222 are connected to external electrodes 223, 224 formed on the side surfaces of the piezoelectric elements 21, 22, respectively.

[0026] The base portion 12 is disposed on the base end side of the plurality of piezoelectric elements 21, 22, and is a block-shaped member that connects the plurality of piezoelectric elements 21, 22 arranged in two rows of the actuator portion 11. That is, the longitudinal direction of the base portion 12 is along the X direction, and the base portion 12 is configured in the shape of a plate that continues over the entire longitudinal length of the laminated piezoelectric member 201. The base portion 12 is made of the same piezoelectric material as the piezoelectric layers that make up the actuator portion 11, for example.

[0027] Furthermore, the base portion 12, which is part of one end of the laminated piezoelectric member 201 that constitutes the drive piezoelectric elements 21 and the non-drive piezoelectric elements 22, is made up of a dummy layer 212. The dummy layer 212 is made of the same material as the piezoelectric layer 211 that constitutes the actuator section 11, has an electrode on only one side, and is not subjected to an electric field, so is a portion that does not deform. Note that a dummy layer of a predetermined thickness may be formed on the end of the laminated piezoelectric member 201 opposite the base portion 12 as part of the actuator section 11.

[0028] The external electrodes 223, 224 are formed on the surfaces of the plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22, and are configured by gathering the ends of the internal electrodes 221, 222. For example, the external electrode 223 is formed on one end surface in the extension direction of the piezoelectric layer 211. The external electrode 224 is formed on the other end surface in the extension direction of the piezoelectric layer 211.

[0029] The external electrodes 223 and 224 are formed by a known method such as plating or sputtering using Ni, Cr, Au, or the like. The external electrodes 223 and 224 have different polarities. The external electrodes 223 and 224 are disposed on different side surfaces of the plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22, respectively.

[0030] In this embodiment, as an example, the external electrode 223 is an individual electrode, and the external electrode 224 is a common electrode. The external electrodes 223, which serve as individual electrodes for the plurality of drive piezoelectric elements 21 and the plurality of non-drive piezoelectric elements 22, are arranged independently of each other by patterning an electrode layer formed on one side surface of the laminated piezoelectric member 201 in the manufacturing process.

[0031] The external electrodes 223 are connected to the drive circuit 70 on the side surface of the actuator element 11 via an FPC 71 serving as a flexible substrate, which is an example of a wiring board. For example, each external electrode 223 is connected to the control unit 116 serving as a drive unit via a drive IC 72 of the drive circuit 70 by the FPC 71, and is configured to be drive-controllable under control of the control circuit 1161. The external electrode 224 may be routed to the side surface on the external electrode 223 side, and connected to the drive circuit 70 via the FPC 71.

[0032] An external electrode 224 formed on the other end face of the actuator element 11 is continuous with the area closer to the base element 12 than the bottom of the groove 23, and forms a common electrode. The external electrode 224 is, for example, grounded.

[0033] For example, both side surfaces of the base portion 12 have outer surfaces that are recessed inward relative to the outer surfaces of the actuator portion 11 on which the external electrodes 223 are formed. For example, at a predetermined location of the dummy layer 212 on the other side in the stacking direction relative to the groove 23, a step 27 is formed in which one side in the stacking direction is recessed inward relative to the other side, and the outer surface of the base portion 12 is recessed in a direction away from the FPC 70.

[0034] The vibration direction of each of the piezoelectric elements 21 and 22 is along the stacking direction, and when an electric field is applied, they are displaced in the d33 direction.

[0035] For example, each of the piezoelectric elements 21 and 22 has 3 to 50 layers, each layer having a thickness of 10 to 40 μm, and the product of the thickness and the total number of layers is less than 1000 μm.

[0036] The driving piezoelectric element 21 vibrates when a voltage is applied to the internal electrodes 221 and 222 via the external electrodes 223 and 224. In this embodiment, the driving piezoelectric element 21 vibrates longitudinally along the stacking direction of the piezoelectric layer 211. The longitudinal vibration here refers to, for example, "vibration in the thickness direction defined by the piezoelectric constant d33." The driving piezoelectric element 21 displaces the vibration plate 30 and deforms the pressure chamber 31 by the longitudinal vibration.

[0037] The flow path member 40 includes a diaphragm 30 disposed opposite one side of the actuator element 11 in the deformation direction, and a flow path substrate 405 laminated on one side of the diaphragm 30.

[0038] The diaphragm 30 is provided between the flow path substrate 405 and the actuator section 11 in the vibration direction. The diaphragm 30, together with the flow path substrate 405, constitutes the flow path member 40. The diaphragm 30 extends in a direction intersecting the side surfaces of the laminated piezoelectric member 201 on which the individual electrodes and the common electrode are formed.

[0039] The vibration plate 30 extends along a plane perpendicular to the Z direction, which is the vibration direction, and is bonded to one side in the vibration direction of the piezoelectric layer 211 of the multiple piezoelectric elements 21, 22, i.e., the surface on the nozzle plate 50 side. The vibration plate 30 is configured to be deformable, for example. The vibration plate 30 is bonded to the drive piezoelectric elements 21 and non-drive piezoelectric elements 22 of the actuator section 11 and to the frame section 60. For example, the vibration plate 30 has a vibration region 301 facing the piezoelectric elements 21, 22, and a support region 302 facing the frame section 60.

[0040] The vibration region 301 is, for example, in the form of a flat plate arranged such that the thickness direction coincides with the vibration direction of the piezoelectric layer 211. The vibration plate 30 has a surface extending in the direction in which the multiple drive piezoelectric elements 21 and the multiple non-drive piezoelectric elements 22 are arranged. The vibration plate 30 is, for example, a metal plate. The vibration plate 30 has multiple vibration parts that face each pressure chamber 31 and can be displaced individually. The vibration plate 30 is formed by integrally connecting the multiple vibration parts.

[0041] As an example, the vibration plate 30 is made of a nickel or SUS plate, and is configured to have a thickness dimension along the vibration direction of approximately 5 μm to 15 μm. Note that the vibration region 301 may have folds or steps formed in areas adjacent to a vibration region or between adjacent vibration regions to facilitate displacement of multiple vibration regions. The vibration region 301 is deformed when the area opposite the drive piezoelectric element 21 is displaced due to expansion and compression of the drive piezoelectric element 21. For example, since the vibration plate 30 needs to be very thin and have a complex shape, it is formed by electroforming or the like. The vibration plate 30 is joined to the upper end surface of the actuator section 11 by adhesive or the like.

[0042] The support region 302 is a plate-like member disposed between the frame portion 60 and the flow path substrate 405. The support region 302 has a communication portion 33 having a through-hole communicating with the common chamber 32.

[0043] For example, the communication portion 33 includes a filter member having a large number of pores as through-holes through which liquid can pass.

[0044] The flow path substrate 405 is disposed between the nozzle plate 50 and the vibration plate 30 in the vibration direction. The flow path substrate 405 is bonded to one side of the vibration plate 30 in the vibration direction.

[0045] The flow path substrate 405 has wall members such as a guide wall portion 41 and a partition portion 42, and forms a predetermined ink flow path having a plurality of pressure chambers 31 that are separated from each other, and a plurality of individual flow paths that are separated from each other and connect the pressure chambers 31 to a common chamber 32.

[0046] Within the flow path substrate 405, the multiple pressure chambers 31 are separated by partition walls 42. That is, both sides of the pressure chambers 31 in the parallel arrangement direction are formed by partition walls 42. Each pressure chamber 31 communicates with a nozzle 51 formed in a nozzle plate 50 disposed on one side. Furthermore, the pressure chamber 31 is closed on the side opposite the nozzle plate 50 by a vibration plate 30.

[0047] The multiple pressure chambers 31 are spaces formed on one side of the vibration region 301 of the vibration plate 30, and communicate with the common chamber 32 via individual flow paths and communication parts 33. The multiple pressure chambers 31 communicate with nozzles 51 formed in the nozzle plate 50. In addition, the pressure chambers 31 are closed on the side opposite to the nozzle plate 50 by the vibration plate 30.

[0048] The pressure chambers 31 hold liquid supplied from a common chamber 32 and are deformed by vibration of a vibration plate 30 that forms part of the pressure chambers 31, thereby ejecting the liquid from the nozzles 51.

[0049] The partition wall portions 42 are wall members that separate the multiple pressure chambers 31 lined up in the parallel direction and that form both side portions of the pressure chambers 31. The partition wall portions 42 are disposed opposite the non-driven piezoelectric elements 22 via the vibration plate 30, and are supported by the non-driven piezoelectric elements 22. A plurality of partition wall portions 42 are provided at the same pitch as the pitch at which the multiple pressure chambers 31 are lined up.

[0050] The nozzle plate 50 is configured as a square 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 flow path substrate 405 so as to cover the openings on one side of the pressure chambers 31.

[0051] A plurality of nozzles 51 are arranged in a first direction, which is the same as the arrangement direction of the pressure chambers 31, to form a nozzle row. For example, two rows of nozzles 51 are provided, and each nozzle 51 is provided at a position corresponding to the plurality of pressure chambers 31 arranged in the two rows. In this embodiment, the nozzles 51 are provided at the end positions of the pressure chambers 31 in the extension direction.

[0052] The frame portion 60 is a structure that is bonded to the vibration plate 30 together with the piezoelectric elements 21 and 22. The frame portion 60 is provided on the side of the vibration plate 30 opposite the flow path substrate 405 of the piezoelectric elements 21 and 22, and is disposed adjacent to the actuator portion 11 in this embodiment, for example. The frame portion 60 forms the outer shell of the liquid ejection head 1. The frame portion 60 may also form a liquid flow path therein. In this embodiment, the frame portion 60 is bonded to the other side of the vibration plate 30, and forms a common chamber 32 between itself and the vibration plate 30.

[0053] The common chamber 32 is formed inside the frame portion 60 and communicates with the pressure chamber 31 through a communication portion 33 provided in the diaphragm 30 and an individual flow path.

[0054] The drive circuit 70 comprises an FPC 71 (Flexible printed circuits) connected to the actuator section 11 via various wiring, a drive IC 72 mounted on the FPC 71, and a printed wiring board mounted on the other end of the FPC 71.

[0055] The drive circuit 70 applies a drive voltage to the external electrodes 223 and 224 by the drive IC 72 to drive the drive piezoelectric element 21 , increase or decrease the volume of the pressure chamber 31 , and cause droplets to be ejected from the nozzle 51 .

[0056] The FPC 71 is connected to the side surface of the actuator section 11, and is connected to a plurality of external electrodes 223, 224 of the actuator section 11. As the FPC 71, a COF (Chip on Film) on which a driving IC 72 is mounted as an electronic component is used.

[0057] The FPC 71 has a wiring layer formed in a predetermined pattern. The FPC 71 is bonded to the side of the actuator section 11 on which the external electrodes 223 are formed. At this time, the external electrodes 223 and the wiring layer are arranged opposite each other and are electrically connected by, for example, solder mounting or ACF mounting using an anisotropic conductive film.

[0058] The driving IC 72 is connected to the external electrodes 223 and 224 via the FPC 71. The driving IC 72 is an electronic component used for ejection control.

[0059] The drive IC 72 generates control signals and drive signals for operating each drive piezoelectric element 21. The drive IC 72 generates control signals for controlling, for example, the timing of ink ejection and the selection of drive piezoelectric elements 21 for ink ejection, in accordance with an image signal input from the control unit 116 of the liquid ejection device 100 in which the liquid ejection head 1 is mounted. The drive IC 72 also generates a voltage, i.e., a drive signal, to be applied to the drive piezoelectric elements 21 in accordance with the control signal from the control unit 116. When the drive IC 72 applies the drive signal to the drive piezoelectric elements 21, the drive piezoelectric elements 21 displace the diaphragm 30, driving the drive piezoelectric elements 21 to change the volume of the pressure chambers 31. This causes pressure vibrations in the ink filled in the pressure chambers 31. The pressure vibrations cause ink to be ejected from the nozzles 51 connected to the pressure chambers 31. The liquid ejection head 1 may be configured to achieve gradation expression by changing the amount of ink droplets that land on one pixel. The liquid ejection head 1 may also be configured to change the amount of ink droplets that land on one pixel by changing the number of ink ejections. In this way, the driving IC 72 is an example of an application unit that applies a driving signal to the driving piezoelectric element 21.

[0060] For example, the drive IC 72 includes a data buffer, a decoder, and a driver. The data buffer stores print data for each drive piezoelectric element 21 in chronological order. The decoder controls the driver for each drive piezoelectric element 21 based on the print data stored in the data buffer. The driver outputs a drive signal that operates each drive piezoelectric element 21 under the control of the decoder. The drive signal is, for example, a voltage applied to each drive piezoelectric element 21.

[0061] The printed wiring board is a PWA (Printing Wiring Assembly) on which various electronic components and connectors are mounted, and has a head control circuit. The printed wiring board is connected to the control unit 116 of the liquid ejection device 100.

[0062] In the liquid ejection head 1 configured as described above, the nozzle plate 50, frame portion 60, flow path substrate 405, and diaphragm 30 form an ink flow path having a plurality of pressure chambers 31 communicating with the nozzles 51 and a common chamber 32 communicating with each of the 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 of the driving piezoelectric elements 21 are connected by wiring so that a voltage can be applied. In the liquid ejection head 1, when the control unit 116 of the liquid ejection device 100 applies a driving voltage to the electrodes 221, 222 using the driving IC 72, the driving piezoelectric element 21 to be driven vibrates, for example, in the stacking direction, i.e., in the thickness direction of each piezoelectric layer 211. In other words, the driving piezoelectric element 21 vibrates vertically.

[0063] Specifically, the control unit 116 applies a drive voltage to the internal electrodes 221, 222 of the drive piezoelectric element 21 to be driven, thereby selectively driving the drive piezoelectric element 21 to be driven. Then, the drive piezoelectric element 21 to be driven deforms the vibration plate 30 by combining deformation in the tensile direction and deformation in the compressive direction, thereby changing the volume of the pressure chamber 31, thereby guiding liquid from the common chamber 32 and ejecting it from the nozzle 51.

[0064] An example of a manufacturing method for the liquid ejection head 1 according to this embodiment will be described. First, internal electrodes 221, 222 are formed by printing on a sheet-shaped piezoelectric material. At this time, a dummy layer 212 having a predetermined thickness that constitutes the base portion 12 is laminated on one end in the lamination direction. Then, multiple piezoelectric layers 211 and dummy layers 212 each having the internal electrodes 221, 222 are laminated, and a firing process and a polarization process are performed to form the laminated piezoelectric member 201 shown in FIG.

[0065] Second grooves 25 extending in the parallel direction are formed in the center of the laminated piezoelectric member 201, dividing the laminated piezoelectric member 201 into two rows. At this time, the second grooves 25 are formed to a depth that reaches the base portion 12 formed by the dummy layer 212, and are deeper than the multiple first grooves 23 that divide the multiple element portions 21 and 22 in the first direction. In other words, the second grooves 25 reach the other side in the stacking direction beyond the first grooves 23. In other words, the second grooves 25 are formed to a position that is farther away from the vibration plate 30 arranged opposite one side of the actuator portion 11 than the first grooves 23 in the stacking direction.

[0066] Then, the piezoelectric elements 21 of the laminated piezoelectric member 201 on which the internal electrodes 221 and 222 have been formed in advance are subjected to polarization treatment.

[0067] The surface of the laminated piezoelectric member 201 is processed using a tool such as a diamond cutter to shape the outer surface of the laminated piezoelectric member 201. This ensures the flatness of the top surface of the actuator section 11 to which the vibration plate 30 will be bonded in a later process.

[0068] Next, electrode layers that become the external electrodes 223, 224 are formed by printing on one and the other end faces of the laminated piezoelectric member 201. As an example, an electrode may be formed once on the top of the actuator element 11, and in this case, the external electrodes 223, 224 are spaced apart by removing the electrode on the top of the actuator element 11 by polishing or the like.

[0069] Next, a portion of one end of the side surface of the actuator unit 11 on which the external electrode 223 is formed is removed to form a step 27. Next, a tool such as a diamond cutter is moved in the Z direction to perform processing, thereby forming a plurality of first grooves 23 that divide the laminated piezoelectric member 201 into a plurality of pieces in the first direction. At this time, the plurality of grooves 23 are simultaneously formed at a predetermined pitch in the X direction to divide the laminated piezoelectric member 201 into a plurality of pieces, thereby forming a plurality of columnar elements that become a plurality of piezoelectric elements 21, 22 arranged at the same pitch. As a result of the above, a plurality of drive piezoelectric elements 21 and non-drive piezoelectric elements 22 arranged at the same pitch are formed.

[0070] Here, the first groove 23 is deeper than the position of the step 27 in the stacking direction, which is the Z direction. In other words, the first groove 23 reaches the other side of the step 27 in the stacking direction. That is, the first groove 23 is formed in the stacking direction to a position farther away from the vibration plate 30 arranged opposite one side of the actuator section 11 than the position of the step 27. With this configuration, the electrode layer constituting the external electrode 223 is divided into individual elements, and individual electrodes are formed. Furthermore, the depth of the groove 23 does not reach the entire length of the actuator section 11, so that a portion is left, and the base section 12 is formed in a region on the base end side of the bottom surface of the groove 23.

[0071] Furthermore, an FPC 71 on which electronic components such as a driver IC 72 are mounted as control components is electrically and mechanically connected, for example, by solder mounting or ACF mounting using an anisotropic conductive film, to a mounting portion on the side of the actuator section 11. Furthermore, a printed wiring board having a head control circuit is connected to the FPC 71.

[0072] Then, the vibration plate 30, flow path substrate 405, and nozzle plate 50 are stacked on the actuator section 11 with bonding material in between to position them, and the frame section 60 is placed around the outer periphery of the actuator section 11, and these multiple components are bonded together to complete the liquid ejection head 1.

[0073] An example of a liquid ejection device 100 including the liquid ejection head 1 will be described below with reference to Fig. 5. The liquid ejection device 100 includes a housing 111, a medium supply unit 112, an image forming unit 113, a medium ejection unit 114, a conveying device 115, and a control unit 116.

[0074] The liquid ejection device 100 is an inkjet recording 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 R that runs from a medium supply section 112 through an image forming section 113 to a medium ejection section 114.

[0075] The housing 111 constitutes the outer shell of the liquid ejection device 100. The housing 111 has an outlet at a predetermined location for ejecting the paper P to the outside.

[0076] 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.

[0077] The medium discharge unit 114 includes a paper discharge tray configured to be able to hold the paper P discharged from the discharge port.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] The head unit 130 includes multiple (four color) liquid ejection heads 1, ink tanks 132 as liquid tanks mounted on each liquid ejection head 1, a connection flow path 133 connecting the liquid ejection heads 1 and the ink tanks 132, and a supply pump 134.

[0082] In this embodiment, the liquid ejection heads 1 are provided with four colors of ink: cyan, magenta, yellow, and black, and ink tanks 132 that contain ink of each color. The ink tanks 132 are connected to the liquid ejection heads 1 by connection flow paths 133.

[0083] 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 liquid ejection head 1 and the ink tank 132, thereby causing the ink supplied to each nozzle 51 of the liquid ejection head 1 to form a meniscus of a predetermined shape.

[0084] The supply pump 134 is a liquid transfer pump formed, for example, by a piezoelectric pump. The supply pump 134 is provided in a supply flow path. The supply pump 134 is connected to a control circuit 1161 of the control unit 116 by wiring, and is configured to be controllable by the control unit 116. The supply pump 134 supplies liquid to the liquid ejection head 1.

[0085] The conveying device 115 conveys the paper P along a conveying path R 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 R.

[0086] 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 R.

[0087] 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 R. Sensors for detecting the conveying status of the paper are arranged at various points along the conveying path R.

[0088] The control unit 116 includes a control circuit 1161 such as a CPU (Central Processing Unit) which is 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.

[0089] In the liquid ejection device 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 liquid ejection head 1. As an ejection operation, the liquid ejection head 1 sends a drive signal to the drive IC 72 using an image signal corresponding to image data, which applies a drive voltage to the internal electrodes 221 and 222 to selectively drive the drive piezoelectric elements 21 to be ejected, causing them to vibrate vertically in the stacking direction, for example, and change the volume of the pressure chambers 31, thereby ejecting ink from the nozzles 51 and forming an image on the paper P held on the conveyor belt 118. As a liquid ejection 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 liquid ejection head 1.

[0090] Here, the driving operation for driving the liquid ejection head 1 will be described. The liquid ejection head 1 according to this embodiment includes driving piezoelectric elements 21 arranged opposite the pressure chambers 31, and these driving piezoelectric elements 21 are connected by wiring so that a voltage can be applied thereto. The control unit 116 sends a driving signal to the driving IC 72 based on an image signal corresponding to image data, and applies a driving voltage to the internal electrodes 221, 222 of the driving piezoelectric elements 21 to be driven, thereby selectively deforming the driving piezoelectric elements 21 to be driven. Then, the volume of the pressure chambers 31 is changed by combining the deformation in the tensile direction and the deformation in the compressive direction of the vibration plate 30, thereby ejecting liquid.

[0091] For example, the control unit 116 alternately performs a tensioning operation and a compression operation. In the liquid ejection head 1, when tensioning to increase the internal volume of the target pressure chamber 31, the drive piezoelectric element 21 to be driven is contracted, and the drive piezoelectric elements 21 that are not the drive targets are not deformed. Also, in the liquid ejection head 1, when compression to decrease the internal volume of the target pressure chamber 31 is performed, the target drive piezoelectric element 21 is expanded. Note that the non-driven piezoelectric elements 22 are not deformed.

[0092] According to the liquid ejection head 1 of the embodiment described above, by configuring the piezoelectric member 10 to integrally include the actuator portion 11 and the base portion 12, it is possible to arrange a plurality of actuator rows with high precision.

[0093] Furthermore, the actuator section 11 is made of a lead-free piezoelectric material, which is preferable from an environmental perspective. Furthermore, the piezoelectric member 10 uses a potassium sodium niobate (KNN)-based piezoelectric material, which allows it to be configured to be harder and more rigid than lead zirconate titanate (PZT), and in particular, in a configuration in which fine columnar elements are arranged, it is possible to make the columnar elements less likely to break at their bases.

[0094] Furthermore, by forming a step 27 where the outer surface of the base portion 12 is recessed inward from the actuator portion 11 side, the external electrodes 223 can be individually separated, and interference with the flexible substrate can be avoided, improving mountability.

[0095] 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.

[0096] In the above embodiment, multiple piezoelectric layers 211 are stacked, and the driving piezoelectric element 21 is driven using longitudinal vibration (d33) in the stacking direction, but this is not limiting. For example, the present invention is applicable to a configuration in which the driving piezoelectric element 21 is configured from a single layer of piezoelectric material, or to a configuration in which the driving element 21 is driven by lateral vibration displacing in the d31 direction.

[0097] The arrangement of the nozzles 51 and pressure chambers 31 is not limited to that in the above embodiment. For example, the nozzles 51 may be arranged in two or more rows. Furthermore, air chambers serving as dummy chambers may be formed between a plurality of pressure chambers 31. The liquid ejection head is not limited to a circulation type, but may also be a non-circulation type, and is not limited to an end shooter type, but may also be a side shooter type liquid ejection head.

[0098] In addition, the configurations and positional relationships of the various components including the flow path member 40, the nozzle plate 50, and the frame portion 60 are not limited to the examples described above, and can be changed as appropriate.

[0099] 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.

[0100] Furthermore, in the above embodiment, the liquid ejection head 1 is used in a liquid ejection device such as a liquid ejection apparatus, but 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.

[0101] According to at least one of the embodiments described above, it is possible to provide a piezoelectric actuator and a liquid ejection head that can ensure high positional accuracy.

[0102] 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. [Explanation of symbols]

[0103] 1...liquid ejection head, 10...piezoelectric member, 11...actuator section, 21...driving piezoelectric element, 22...non-driving piezoelectric element, 23...first groove, 25...second groove, 27...step, 30...vibration plate, 31...pressure chamber, 32...common chamber, 33...communicating section, 40...flow path member, 41...guide wall section, 42...partition wall section, 50...nozzle plate, 51...nozzle, 60...frame section, 70...driving circuit, 100...liquid ejection device, 111...casing, 112...medium supply section, 113...image forming section, 114...medium discharge section, 115...conveying 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, 201...laminated piezoelectric member, 211...piezoelectric layer, 212...dummy layer, 221...internal electrode, 222...internal electrode, 223...external electrode, 224...external electrode, 301...vibration area, 302...support area, 405...flow path substrate, 1161...control circuit.

Claims

1. a laminated piezoelectric member in which a plurality of piezoelectric layers made of a piezoelectric material and a plurality of internal electrode layers are laminated, the laminated piezoelectric member having a plurality of element portions arranged in a first direction and divided by a plurality of first grooves formed on one side of the lamination direction; a base portion formed of a piezoelectric material and arranged continuously on the other side of the plurality of element portions in the stacking direction; A piezoelectric actuator comprising:

2. 2. The piezoelectric actuator according to claim 1, wherein the piezoelectric material constituting the base portion and the plurality of element portions is a lead-free piezoelectric material.

3. 2. The piezoelectric actuator according to claim 1, wherein the piezoelectric material constituting the base portion and the element portion is a KNN-based piezoelectric material.

4. a plurality of element rows in which the element portions are aligned in a first direction are arranged in a second direction different from the first direction via second grooves; A step is formed on the side surface in the second direction, such that the other side in the stacking direction is recessed more inward than the one side, In the stacking direction, the first groove reaches the other side in the stacking direction beyond the step, the second groove extends to the other side in the stacking direction beyond the first groove; The piezoelectric actuator according to claim 1 .

5. A piezoelectric actuator according to any one of claims 1 to 4; a flow path portion having a plurality of pressure chambers arranged opposite the plurality of element portions and nozzles communicating with the pressure chambers; A liquid ejection head comprising:

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