Liquid discharge head and method for manufacturing liquid discharge head

Abstract

To provide a liquid discharge head that can improve strength, and to provide a method for manufacturing a liquid discharge head.SOLUTION: A liquid discharge head includes a piezoelectric member. The piezoelectric member has one side that is divided by grooves in one direction where a plurality of piezoelectric elements is formed and to which the other side is connected. An individual electrode and a common electrode are disposed to the one side and the other side respectively.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] An embodiment of the present invention relates to a liquid ejection head and a method for manufacturing a liquid ejection head. [Background technology]

[0002] An actuator unit using a piezoelectric material such as PZT is used as a driving source for a liquid ejection device such as an inkjet printer head. A piston-type inkjet head is known to have an actuator unit arranged on a vibration plate provided near a pressure chamber. For example, an actuator is attached to each nozzle row.

[0003] For example, the actuator section is made by forming multiple grooves in a piezoelectric body and dividing it into columnar piezoelectric elements, but the finer the piezoelectric element, the weaker its mechanical strength is, and the more likely it is to be damaged during machining to separate the piezoelectric body. In particular, piezoelectric elements with a laminated structure in which multiple piezoelectric layers and electrode layers are laminated are prone to damage from the interface between the piezoelectric layers and the electrode layers. [Prior art documents] [Patent documents]

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

[0005] An object of the present invention is to provide a liquid ejection head capable of improving strength, and a method for manufacturing the liquid ejection head. [Means for solving the problem]

[0006] A liquid ejection head according to one embodiment includes a piezoelectric member, the piezoelectric member being divided by grooves on one side in one direction to form a plurality of piezoelectric elements, and the piezoelectric member being connected on the other side, and individual electrodes and a common electrode being disposed on the one side and the other side, respectively. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view showing a configuration of an inkjet head according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing the configuration of the inkjet head. [Diagram 3] FIG. 2 is a plan view of an actuator unit of the inkjet head. [Figure 4] FIG. 2 is a side view showing a configuration of a part of the actuator unit of the inkjet head. [Diagram 5] FIG. 1 is an explanatory diagram showing a schematic configuration of an inkjet recording apparatus according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] An inkjet head 1, which is a liquid ejection head according to an embodiment, and an inkjet recording device 100, which is a liquid ejection device, will be described below with reference to Figs. 1 to 5. Figs. 1 and 2 are cross-sectional views showing a schematic configuration of the inkjet head 1. Fig. 3 is a plan view of an actuator unit of the inkjet head, and Fig. 4 is a side view showing a partial configuration of the actuator unit. Fig. 5 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 perpendicular to each other. For the sake of explanation, the configuration is enlarged, reduced, or omitted in each figure as appropriate.

[0009] As shown in Figures 1 and 2, the inkjet head 1 includes a base 10, a pair of actuator members 20, a flow path member 40, a nozzle plate 50 having a plurality of nozzles 51, a frame portion 60 as a structural portion, and a drive circuit 70.

[0010] As an example, the inkjet head 1 has two rows each of a nozzle row in which a plurality of nozzles 51 are arranged in a row direction (X direction), a pressure chamber row in which a plurality of pressure chambers 31 are arranged in the row direction, and an element row in which a plurality of piezoelectric elements 21, 22 are arranged in the row direction. In this embodiment, an example is shown in which the depth direction of the plurality of grooves 23 is aligned along the Y direction as one direction, and the stacking direction of the plurality of piezoelectric layers 211, the vibration direction of the piezoelectric elements 21, and the vibration direction of the diaphragm 30 are each aligned along the Z direction.

[0011] The base 10 is a member that supports the pair of actuator parts 20. The base 10 is formed, for example, in a plate or block shape. For example, the base 10 is made of a material that is easy to process and has high hardness, such as SUS or alumina.

[0012] The actuator section 20 is joined to a mounting surface that is one side in the stacking direction of the base 10. For example, two actuator sections 20 are arranged side by side in one direction (Y direction) that is perpendicular to or intersects with the stacking direction.

[0013] 1 to 4, the actuator section 20 is made of, for example, a piezoelectric material and includes a plurality of driving piezoelectric elements 21 and a plurality of non-driving piezoelectric elements 22 serving as actuators alternately arranged along the column direction, and a connecting section 26 connecting the plurality of piezoelectric elements 21, 22. The piezoelectric material is a laminated piezoelectric material 201 in which a plurality of piezoelectric layers 211 and a plurality of internal electrode layers 221, 222 are laminated.

[0014] In the actuator section 20, the multiple driving piezoelectric elements 21 and the multiple non-driving piezoelectric elements 22 are arranged at regular intervals in the column direction. One side of the pair of actuator sections 20 in one direction is divided by a groove 23 to form the multiple piezoelectric elements 21, 22, and the other side is connected by a connecting section 26.

[0015] As an example, the plurality of driving piezoelectric elements 21 and the plurality of non-driven piezoelectric elements 22 are both configured in the shape of a rectangular parallelepiped column with the same external shape. The actuator section 20 is configured in a comb shape with the individual electrode side divided into multiple parts by the plurality of grooves 23, and the plurality of driving piezoelectric elements 21 and the plurality of non-driven piezoelectric elements 22 are alternately arranged in the column direction at the same pitch by the grooves 23 of the same width.

[0016] For example, the groove 23 is formed over the entire length of the actuator section 20 in the stacking direction. Also, the groove 23 is formed in the depth direction (Y direction) from an end surface portion on one side of the actuator section 20 to a middle portion of the actuator section 20. For example, by forming the groove 23 at a depth that does not reach the end portion on the other side where the external electrode 223 forming the individual electrode is formed and the external electrode 224 forming the common electrode is formed, one side is configured as a comb tooth shape with a free end, and a plurality of elements 21, 22 are arranged on one side, and the end portion on the other side is connected to form a connecting portion 26, and configured as a cantilever beam. Therefore, the external electrode 223 on one end side is divided into a plurality of parts to form a plurality of individual electrodes, and the external electrode 224 is integrally and continuously formed on the side surface portion on the other side of the laminated piezoelectric member 201 to form a common electrode. That is, in the laminated piezoelectric member 201, the individual electrodes and the common electrode are respectively arranged on one side and the other side.

[0017] For example, the plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22 are each configured in a rectangular shape in a plan view seen from the Z direction, with the short side direction aligned with the row direction of the element row and the long side aligned with one direction (Y direction) perpendicular to the row direction and the Z direction, and are connected at one end side in one direction (Y direction). As an example, the opposing sides of a pair of actuator parts 20 arranged opposite to one direction (Y direction) are integrally connected, and the opposite side is divided into a plurality of parts. A retreat part 25 is formed at the end part on the individual electrode side of each of the piezoelectric elements 21, 22. That is, of the end faces of the piezoelectric elements 21, 22 joined to the base 10, the end part on one side in one direction is notched in a stepped or tapered shape, and a part of the end face on the individual electrode side on the base 10 side is retreated. For example, the retreat part 25 is provided in the electrode non-facing part 203 which is a dummy layer. That is, of the piezoelectric element 21, a part that does not function as a piezoelectric body and does not deform is partially cut out.

[0018] The driving piezoelectric elements 21 are arranged in positions in the Z direction facing the multiple pressure chambers 31 formed in the flow path member 40. As an example, the center positions in the row direction of the driving piezoelectric elements 21 and the center positions in the row direction of the pressure chambers 31 are arranged side by side in the Z direction.

[0019] The non-driven piezoelectric elements 22 are arranged in positions in the Z direction facing the multiple partition walls 42 formed in the flow path member 40. As an example, the center positions in the row direction of the non-driven piezoelectric elements 22 and the center positions in the row direction of the partition walls 42 are arranged side by side in the Z direction.

[0020] For example, the actuator unit 20 is formed by dicing the laminated piezoelectric member 201 previously bonded to the base 10 from the end face opposite to the opposing face to form grooves 23, thereby forming a plurality of rectangular columnar piezoelectric elements at predetermined intervals. Then, electrodes and the like are provided on the formed columnar elements to form a plurality of driving piezoelectric elements 21 and a plurality of non-driven piezoelectric elements 22 that are alternately arranged. The driving piezoelectric elements 21 and the non-driven piezoelectric elements 22 are alternately arranged in parallel in the column direction with the grooves 23 between them.

[0021] For example, the laminated piezoelectric member 201 constituting the actuator section 20 is formed by laminating and sintering sheet-shaped piezoelectric materials.

[0022] The piezoelectric member constituting the driving piezoelectric element 21 and the non-driven piezoelectric element 22 is, for example, a laminated piezoelectric member 201. The driving piezoelectric element 21 and the non-driven piezoelectric element 22 each include a plurality of laminated piezoelectric layers 211 and internal electrode layers 221, 222 formed on the main surface of each piezoelectric layer 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 surface.

[0023] For example, the laminated piezoelectric member 201 has an electrode facing portion 202 where the electrodes 221, 222 of different polarities face each other in the lamination direction, and electrode non-facing portions 203, 204 where only the electrodes 221 or 222 of the same polarity are laminated and the electrodes 221, 222 of different polarities do not face each other. For example, the electrode non-facing portions 203, 204 are formed on both sides of the electrode facing portion 202 in one direction (Y direction) which is the depth direction of the groove 23. Here, the center of the electrode facing portion 202 in one direction (Y direction) is located closer to the individual electrode side than the center position of the actuator unit 20. That is, in this embodiment, the electrode non-facing portion 204 at the end on the common electrode side of the actuator unit 20 in one direction is larger than the electrode non-facing portion 203 at the end on the individual electrode side. That is, the center position of the electrode facing portion 202 where the electrodes 221, 222 of different polarities are arranged to face each other in one direction is located on one side of the center position of the laminated piezoelectric member 201. That is, the actuator section 20 is configured such that the internal electrode layers 221, 222 are arranged asymmetrically in one direction such that the non-electrode facing portion 204 on the common electrode side is larger than the non-electrode facing portion 203 on the individual electrode side.

[0024] For example, the non-electrode facing parts 203 and 204 are formed on either or both of the ends on the base 10 side and the nozzle plate 50 side. The non-electrode facing parts 203 and 204 are made of the same material as the piezoelectric layer 211, for example, and have electrodes on only one side, so that they constitute a dummy layer to which no electric field is applied. In other words, the non-electrode facing parts 203 and 204 do not deform and serve as a base for fixing the actuator part 20 to the base 10, or as a polishing allowance for polishing to achieve precision during or after assembly. In this embodiment, at least the entire length of the non-electrode facing part 203 on the individual electrode side and the electrode facing part 202 is separated into a plurality of parts in the column direction by the groove 23 to constitute the elements 21 and 22, and at least a part of the non-electrode facing part 204 on the common electrode side constitutes the connecting part 26.

[0025] Furthermore, in the actuator section 20, for example, the end portion on the base 10 side may constitute a dummy layer in which the internal electrode layers 221, 222 are not arranged.

[0026] The piezoelectric layer 211 is formed in a thin plate shape from a piezoelectric ceramic material such as PZT (lead zirconate titanate) or lead-free KNN (potassium sodium niobate). The multiple piezoelectric layers 211 are laminated with their thickness direction aligned with the lamination direction and are bonded to each other. For example, in this embodiment, the thickness direction and lamination direction of the piezoelectric layers 211 are arranged along the vibration direction (Z direction).

[0027] The internal electrode layers 221 and 222 are conductive films formed in a predetermined shape from a sinterable conductive material such as silver palladium. The internal electrode layers 221 and 222 are formed in a predetermined region on the main surface of each piezoelectric layer 211. The internal electrode layers 221 and 222 have different poles. For example, one internal electrode layer 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 a depth direction (Y direction) that is a direction perpendicular to both the row direction (X direction) in which the multiple driving piezoelectric elements 21 and the multiple non-driving piezoelectric elements 22 are arranged and the vibration direction (Z direction). The other internal electrode layer 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 one direction. The internal electrode layers 221 and 222 are connected to external electrodes 223 and 224 formed on the side surfaces of the piezoelectric elements 21 and 22, respectively.

[0028] The external electrodes 223, 224 are formed on the surfaces of the multiple driving piezoelectric elements 21 and the multiple non-driven piezoelectric elements 22, and are configured by collecting the ends of the internal electrode layers 221, 222. For example, the external electrode 223 is formed on one end face in one direction of the piezoelectric layer 211. The external electrode 224 is formed on the other end face in one 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, etc. The external electrodes 223 and 224 have different polarities. The external electrodes 223 and 224 are disposed on different side portions of the multiple driving piezoelectric elements 21 and the multiple 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 electrode 223, which serves as an individual electrode for the multiple driving piezoelectric elements 21 and the multiple non-driven piezoelectric elements 22, is formed by dividing an electrode layer formed on one end face of the laminated piezoelectric member 201 in the manufacturing process into multiple parts by grooves 23, so that independent individual electrodes are formed at a distance from each other in the parallel direction.

[0031] The external electrodes 223 are connected to the drive circuit 70 via an FPC 71 serving as a flexible substrate, which is an example of a wiring board. For example, each of the external electrodes 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 by the control of the control circuit 1161.

[0032] The external electrode 224 is composed of an electrode layer formed on the other end face of the actuator section 20. That is, the external electrodes 224 are connected to each other on the other end face of the laminated piezoelectric member 201 to form a common electrode. The external electrode 224 is routed around the side surface on the external electrode 223 side, and may be connected to the drive circuit 70 via the FPC 71 or may be grounded.

[0033] 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.

[0034] As an example, each of the piezoelectric elements 21, 22 has 3 to 50 layers, each layer has a thickness of 10 to 40 μm, and the product of the thickness and the total number of layers is less than 1000 μm.

[0035] The driving piezoelectric element 21 vibrates when a voltage is applied to the internal electrode layers 221, 222 via the external electrodes 223, 224. In this embodiment, the driving piezoelectric element 21 vibrates longitudinally along the stacking direction of the piezoelectric layer 211. The longitudinal vibration here means, 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.

[0036] The flow path member 40 includes a diaphragm 30 disposed opposite one side of the actuator section 20 in the deformation direction, and a flow path substrate 405 laminated on one side of the diaphragm 30.

[0037] The diaphragm 30 is provided between the flow path substrate 405 and the actuator section 20 in the vibration direction. The diaphragm 30, together with the flow path substrate 405, constitutes a flow path member 40. The diaphragm 30 extends in a direction intersecting with the side surface of the laminated piezoelectric member 201 on which the individual electrodes and the common electrode are formed.

[0038] 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 driving piezoelectric element 21 and the non-driving piezoelectric element 22 of the actuator section 20, 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.

[0039] The vibration region 301 is, for example, a flat plate arranged such that the thickness direction is the vibration direction of the piezoelectric layer 211. The vibration plate 30 has a surface extending in the direction in which the driving piezoelectric elements 21 and the non-driving piezoelectric elements 22 are arranged. The vibration plate 30 is, for example, a metal plate. The vibration plate 30 is arranged opposite to each pressure chamber 31 and bonded, and has a plurality of bonding parts 304 that can be individually displaced. For example, the bonding parts 304 are transmission parts that transmit vibration. The bonding parts 304 may be integrally provided as part of the vibration plate 30, or may be composed of a separate member. For example, the plurality of bonding parts 304 may be in the form of protrusions that protrude toward the actuator part 20, or may be composed of a part of the flat vibration plate 30.

[0040] For example, the joint 304 is disposed at a position closer to the individual electrode than the center in one direction of the actuator unit 20. That is, the joint 304 is disposed at a position biased toward one side where the multiple piezoelectric elements 21, 22 are separated and become free ends, rather than the base end side where the multiple piezoelectric elements 21, 22 are connected. For example, in one direction, the center position of the joint 304 bonded to the vibration plate 30 is disposed opposite the center position of the electrode opposing portion 202. Therefore, the joint 304 is disposed at a position far from the end on the common electrode side and close to the end on the individual electrode side.

[0041] As an example, the vibration plate 30 is made of nickel or SUS plate, and the thickness dimension along the vibration direction is set to about 5 μm to 15 μm. The vibration region 301 may have folds or steps formed in the region adjacent to the vibration region or between adjacent joints so that the multiple joints 304 can be easily displaced. The vibration region 301 is deformed by the displacement of the joints 304 arranged opposite the driving piezoelectric element 21 due to the expansion and compression of the driving piezoelectric element 21. For example, the vibration plate 30 is required to be very thin and have a complex shape, and is formed by electroforming or the like. The vibration plate 30 is bonded to the upper end surface of the actuator section 20 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 diaphragm 30 in the vibration direction. The flow path substrate 405 is bonded to one side of the diaphragm 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 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] In 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 the partition walls 42. Each pressure chamber 31 communicates with a nozzle 51 formed in a nozzle plate 50 disposed on one side. In addition, the pressure chamber 31 is closed by a vibration plate 30 on the side opposite the nozzle plate 50.

[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 a part of the pressure chambers 31 , thereby ejecting the liquid from a nozzle 51 .

[0049] The partitions 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 partitions 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 partitions 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 rectangular plate having a thickness of about 10 μm to 100 μm and 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 of the pressure chambers 31 on one side.

[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 end positions of the pressure chambers 31 in one direction, which is the depth direction of the groove 23.

[0052] The frame portion 60 is a structure that is joined 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 20 in this embodiment, for example. The frame portion 60 constitutes the outer shell of the inkjet head 1. The frame portion 60 may also form a liquid flow path therein. In this embodiment, the frame portion 60 is joined to the other side of the vibration plate 30, and forms a common chamber 32 between the frame portion 60 and the vibration plate 30.

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

[0054] The drive circuit 70 includes an FPC 71 (Flexible printed circuits) connected to the external electrodes 223, 224 of the actuator section 20, a drive IC 72 mounted on the FPC 71, and a printed wiring board 73 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 via the drive IC 72 to drive the drive piezoelectric element 21 , thereby increasing or decreasing the volume of the pressure chamber 31 and causing droplets to be ejected from the nozzle 51 .

[0056] The FPC 71 is connected to a plurality of external electrodes 223, 224 of the actuator section 20. 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 driving IC 72 is connected to external electrodes 223 and 224 via the FPC 71. The driving IC 72 is an electronic component used for ejection control.

[0058] The driving IC 72 generates a control signal and a driving signal for operating each driving piezoelectric element 21. The driving IC 72 generates a control signal for controlling the timing of ink ejection and the selection of the driving piezoelectric element 21 for ejecting ink according to an image signal input from the control unit 116 of the inkjet recording device 100 on which the inkjet head 1 is mounted. The driving IC 72 also generates a voltage to be applied to the driving piezoelectric element 21, i.e., a driving signal, according to a control signal from the control unit 116. When the driving IC 72 applies a driving signal to the driving piezoelectric element 21, the driving piezoelectric element 21 is driven to displace the vibration plate 30 and change the volume of the pressure chamber 31. This causes the ink filled in the pressure chamber 31 to generate pressure vibration. The pressure vibration causes ink to be ejected from the nozzle 51 communicating with the pressure chamber 31. The inkjet head 1 may be configured to realize gradation expression by changing the amount of ink droplets that land on one pixel. The inkjet head 1 may also be configured to change the amount of ink droplets that land on one pixel by changing the number of times ink is ejected. In this manner, the driving IC 72 is an example of an application unit that applies a driving signal to the driving piezoelectric element 21.

[0059] 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 based on the control of the decoder. The drive signal is, for example, a voltage applied to each drive piezoelectric element 21.

[0060] The printed wiring board 73 is a PWA (Printing Wiring Assembly) on which various electronic components and connectors are mounted, and has a head control circuit 731. The printed wiring board 73 is connected to the control unit 116 of the inkjet recording apparatus 100.

[0061] In the inkjet head 1 configured as above, the nozzle plate 50, the frame portion 60, the flow path substrate 405, and the vibration plate 30 form an ink flow path having a plurality of pressure chambers 31 communicating with the nozzle 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 the driving piezoelectric elements 21 are connected to each other by wiring so that a voltage can be applied thereto. In the inkjet head 1, when the control unit 116 of the inkjet recording device 100 applies a driving voltage to the electrodes 221 and 222 by the driving IC 72, the driving piezoelectric element 21 to be driven vibrates, for example, in the stacking direction, that is, in the thickness direction of each piezoelectric layer 211. In other words, the driving piezoelectric element 21 vibrates vertically.

[0062] Specifically, the control unit 116 applies a driving voltage to the internal electrode layers 221, 222 of the driving piezoelectric element 21 to be driven, selectively driving the driving piezoelectric element 21 to be driven. Then, the vibration plate 30 is deformed by combining the deformation in the tensile direction and the deformation in the compressive direction by the driving piezoelectric element 21 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.

[0063] An example of a manufacturing method of the inkjet head 1 according to this embodiment will be described. First, the internal electrode layers 221, 222 are formed by printing on a sheet-shaped piezoelectric material. Then, a plurality of piezoelectric layers 211 having the internal electrode layers 221, 222 are laminated, and a firing process and a polarization process are performed to form the laminated piezoelectric member 201.

[0064] Furthermore, external electrodes 223, 224 are formed by printing on one and the other end faces in the second direction of the laminated piezoelectric member 201. Then, by dicing using a tool such as a diamond cutter, multiple grooves 23 of a predetermined depth are formed from one side where the external electrodes 223 serving as individual electrodes are arranged, leaving part of the other side, thereby dividing one side of the laminated piezoelectric member 201 into multiple pieces to form multiple piezoelectric elements 21, 22. For example, as shown in Fig. 4, by placing the individual electrode side on top and dividing the individual electrode side to a predetermined depth, it is possible to maintain the connection of the actuator section 20 on the common electrode surface side. As a result of the above, a piezoelectric member is formed in which one end is divided into several pieces and the other end is connected, and the external electrode 223 on one side is separated to form several independent individual electrodes that are spaced apart from each other. At this time, by leaving a portion of the groove 23 so that it does not reach the entire length in one direction, the external electrode 224 on the side surface on the other side is not separated and forms an integral, continuous common electrode. Also, by removing a portion of the corner on the external electrode 223 side that will become the individual electrode, a retreat portion such as a step or a tapered surface is formed. The retreat portion may be formed before the groove 23.

[0065] Furthermore, the piezoelectric element 21 is polarized and attached to the base 10 with an adhesive or the like.

[0066] Furthermore, an FPC 71 on which electronic components such as a driver IC 72 are mounted as control components is connected, for example, by solder mounting, anisotropic conductive film, etc. Furthermore, a printed wiring board 73 having a head control circuit 731 is connected to the FPC 71.

[0067] Then, the vibration plate 30, the flow path substrate 405, and the nozzle plate 50 are stacked on the actuator section 20 with bonding material between them to determine their position, and the frame section 60 is placed on the outer periphery of the actuator section 20. By bonding these multiple components together, the inkjet head 1 is completed.

[0068] An example of an inkjet recording device 100 including the inkjet head 1 will be described below with reference to Fig. 5. 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.

[0069] 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 R from a medium supply section 112 through an image forming section 113 to a medium ejection section 114.

[0070] 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.

[0071] 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.

[0072] The medium discharge unit 114 includes a paper discharge tray configured to be able to hold the paper P discharged from the discharge opening.

[0073] 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.

[0074] The support section 117 includes a conveyor belt 118 provided in a loop shape in a predetermined area where image formation is performed, a support plate 119 supporting the conveyor belt 118 from the back side, and a plurality of belt rollers 120 provided on the back side of the conveyor belt 118.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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 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 inkjet head 1.

[0080] 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.

[0081] 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 R.

[0082] 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 disposed at various points along the conveying path R.

[0083] The control unit 116 includes a control circuit 1161 such as a CPU (Central Processing Unit) 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, and the like, and an interface unit which inputs data from the outside and outputs data to the outside.

[0084] In the inkjet recording device 100 configured as above, when the control unit 116 detects a print instruction by a user operating an 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 driving IC 72 by an image signal corresponding to image data, applies a drive voltage to the internal electrode layers 221 and 222, and selectively drives the driving piezoelectric element 21 to be discharged, for example, to vibrate vertically in the lamination 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.

[0085] Here, the driving operation for driving the inkjet head 1 will be described. The inkjet head 1 according to this embodiment includes driving piezoelectric elements 21 arranged to face 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 by an image signal corresponding to image data, and applies a driving voltage to the internal electrode layers 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 discharging liquid.

[0086] For example, the control unit 116 alternates between a pulling operation and a compression operation. In the inkjet head 1, during pulling to increase the internal volume of the target pressure chamber 31, the driving piezoelectric element 21 to be driven is contracted, and the driving piezoelectric element 21 that is not the driving target is not deformed. Also, during compression to decrease the internal volume of the target pressure chamber 31 in the inkjet head 1, the target driving piezoelectric element 21 is expanded. Note that the non-driven piezoelectric element 22 is not deformed.

[0087] According to the inkjet head 1 and the inkjet recording device 100 of the above-mentioned embodiment, it is possible to provide a liquid ejection head and a liquid ejection device having high strength and high mountability. That is, compared to a configuration in which one side is divided in the lamination direction, the internal common electrode is supported over a wider area, and therefore, it is expected that the yield rate will be improved by suppressing the destruction from the electrode interface. That is, the yield rate can be improved by reducing the stress applied to the internal electrode layers 221, 222 and reducing the risk of destruction at the interface.

[0088] In the actuator section 20, the individual electrodes are completely separated, and the joint section 304 of the vibration region is disposed in a position close to the individual electrode side, which is the free end, thereby reducing structural crosstalk. In addition, since the common electrode has a large area, the electrode volume increases, and current concentration in the common electrode is prevented when driving the actuator, and a single common electrode wiring can supply electric charge to each actuator common electrode. For example, vibration is small in the non-opposing electrode sections 203 and 204 where the electrodes 221 and 222 of the different internal electrode layers do not overlap each other and do not displace, but by making the non-opposing electrode section 204 on the connecting section 26 side large, the distance to the vibration section can be secured and the influence of crosstalk can be reduced.

[0089] In the above embodiment, the retracted portion 25 is formed on the end face of the actuator portion 20 on the individual electrode side, which is the face on which the FPC 71 is provided, so that interference with peripheral members such as the FPC 71 can be avoided.

[0090] 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.

[0091] For example, the specific materials and configurations of the piezoelectric elements 21 and 22 in the above embodiment are not limited to those described above, and may be changed as appropriate.

[0092] In the above embodiment, a plurality of piezoelectric layers 211 are laminated, and the driving piezoelectric element 21 is driven by longitudinal vibration (d33) in the lamination direction, but the present invention is not limited to this. For example, the present invention can be applied to a configuration in which the driving piezoelectric element 21 is composed of 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.

[0093] The arrangement of the nozzles 51 and the 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. Also, air chambers serving as dummy chambers may be formed between a plurality of pressure chambers 31. The inkjet head may be of a non-circulation type instead of a circulation type, and may be of a side shooter type instead of an end shooter type.

[0094] In addition, the configurations and positional relationships of various parts including the flow path member 40, the nozzle plate 50, and the frame portion 60 are not limited to the above-mentioned examples, and can be changed as appropriate.

[0095] In the above embodiment, an example is shown in which two actuator sections 20 are arranged in parallel on the base 10, but this is not limiting and there may be a single actuator section 20. The actuator section 20 is not limited to being formed over the entire length in the stacking direction, and a portion of the actuator section 20 on the base 10 side may be continuous. A configuration in which a portion of the end on the individual electrode side on the base 10 side is not retracted is also possible.

[0096] 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.

[0097] 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.

[0098] 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 improve mountability.

[0099] 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. [Explanation of symbols]

[0100] 1...inkjet head, 10...base, 20...actuator section, 21...driven piezoelectric element, 22...non-driven piezoelectric element, 23...groove, 26...connecting section, 30...diaphragm, 31...pressure chamber, 32...common chamber, 33...communicating section, 40...flow path member, 42...partition wall section, 50...nozzle plate, 51...nozzle, 60...frame section, 70...drive circuit, 71...FPC, 72...drive IC, 73...printed wiring board, 731...head control circuit, 100...inkjet recording device, 111...housing, 112...medium supply section, 113...image forming section, 114...medium discharge section, 115...transport device , 117...support portion, 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, 116...control portion, 1161...control circuit, 201...laminated piezoelectric member, 202...electrode facing portion, 203, 204...electrode non-facing portion, 211...piezoelectric layer, 221...internal electrode layer, 222...internal electrode layer, 223...external electrode, 224...external electrode, 301...vibration region, 302...support region, 304...joint portion, 405...flow path substrate.

Claims

1. A liquid ejection head comprising a piezoelectric member, one side of which is divided by grooves in one direction to form a plurality of piezoelectric elements, the other side being connected, and individual electrodes and a common electrode being disposed on the one side and the other side, respectively.

2. 2. The liquid ejection head according to claim 1, wherein the piezoelectric member is a laminated piezoelectric member having a plurality of electrode layers and a plurality of piezoelectric layers stacked in a stacking direction intersecting the one direction, the one side being a free end and the other side being connected to each other.

3. The liquid ejection head according to claim 2 , wherein a central position of an electrode opposing portion where electrode layers of different polarities are arranged to face each other in the one direction is located on the one side of a central position of the piezoelectric member.

4. A base is bonded to one side of the piezoelectric member in a stacking direction; a vibration plate disposed opposite the piezoelectric member and extending in a direction intersecting a side surface on which the individual electrodes and the common electrode are formed, The liquid ejection head according to claim 1 , further comprising: a plurality of pressure chambers, at least a portion of which faces said vibration plate; and a plurality of nozzles communicating with said plurality of pressure chambers.

5. A method for manufacturing a liquid ejection head, comprising forming a plurality of grooves in a laminated piezoelectric component having a plurality of piezoelectric layers and a plurality of electrode layers stacked in a stacking direction, the grooves extending from one side in a direction intersecting the stacking direction to a midway portion of the electrode layers in the one direction.

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