Liquid ejection head

Abstract

To provide a liquid discharge head which can secure positional accuracy while securing insulation properties between a diaphragm and a piezoelectric element.SOLUTION: A liquid discharge head includes: a plurality of piezoelectric elements; a structure; a diaphragm; a plurality of first protrusion sections; a second protrusion section; and a plurality of pressure chambers. The plurality of piezoelectric elements are composed of a piezoelectric material. The structure is provided side by side with the plurality of piezoelectric elements. The diaphragm has a plate section. The plurality of first protrusion sections are formed at positions facing the piezoelectric elements on one side of the plate section and are composed of an organic polymer material. The second protrusion section is formed at a position facing the structure on one side of the plate section and is composed of an organic polymer material. The plurality of pressure chambers are formed on the other side of the plate section and are communicated with a plurality of nozzles for discharging liquid.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a liquid ejection head.

Background Art

[0002] In a liquid ejection head such as an inkjet head, a method is used in which a piezoelectric body such as PZT is used to deform a diaphragm, thereby deforming a pressure chamber facing the diaphragm and ejecting ink from a nozzle communicating with the pressure chamber. In such an inkjet head, electrodes may be formed on a surface orthogonal to the diaphragm. If a piezoelectric column is brought into direct contact with the diaphragm, the diaphragm may short-circuit when it is conductive. For this reason, a technique has been provided in which a convex portion narrower than between the electrodes is provided on the diaphragm to prevent the piezoelectric body and the diaphragm from short-circuiting due to electrical connection. However, when fine protrusions are provided at a portion of the diaphragm facing the piezoelectric column, it becomes difficult to ensure the positional accuracy with respect to a peripheral member joined to the diaphragm.

[0003] In such a liquid ejection head, it is required to ensure the positional accuracy while ensuring the insulation between the diaphragm and the piezoelectric element.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem to be solved by the present invention is to provide a liquid ejection head capable of ensuring the positional accuracy while ensuring the insulation between the diaphragm and the piezoelectric element.

Means for Solving the Problems

[0006] A liquid ejection head according to an embodiment includes a plurality of piezoelectric elements which are a laminated piezoelectric body including a plurality of piezoelectric members laminated along a lamination direction, a structure provided side by side with the plurality of piezoelectric elements, and the plurality of piezoelectric elements The above-mentioned a plate portion disposed opposite to one side in the lamination direction, and in the plate portion, the piezoelectric elements The above-mentioned a plurality of first convex portions formed of an organic polymer material at positions facing the end surface on one side in the lamination direction, and in the plate portion, the structure the piezoelectric element in the above-mentioned of The above-mentioned a second convex portion formed of an organic polymer material at a position facing the end surface on one side in the lamination direction, a diaphragm including the same, and the plate portion The above-mentioned a plurality of pressure chambers formed on one side in the lamination direction and communicating with a plurality of nozzles for ejecting liquid. The first convex portion and the second convex portion are configured to have a thickness dimension along the stacking direction smaller than that of the plate portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] [Figure 1] A cross-sectional view showing the configuration of an inkjet head according to the first embodiment. [Figure 2] A perspective view showing a part of the configuration of the inkjet head. [Figure 3] A cross-sectional view showing a part of the configuration of the inkjet head. [Figure 4] An explanatory view showing a schematic configuration of an inkjet recording apparatus according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, the inkjet head 1 which is a liquid ejection head according to the first embodiment and the inkjet recording apparatus 100 which is a liquid ejection apparatus will be described with reference to FIGS. 1 to 4. FIG. 1 is a cross-sectional view showing a schematic configuration of the inkjet head 1, and FIG. 2 is a perspective view showing a schematic configuration of a part of the inkjet head 1. FIG. 3 is a cross-sectional view showing a configuration of a part of the inkjet head. FIG. 4 is an explanatory view showing a schematic configuration of the inkjet recording apparatus 100. Arrows X, Y, and Z in the figures respectively indicate three mutually orthogonal directions. For the sake of explanation in each figure, the configuration is appropriately enlarged, reduced, or omitted.

[0009] As shown in FIGS. 1 to 3, the inkjet head 1 includes a base 10, a piezoelectric member 20, a diaphragm 30, a manifold 40, a nozzle plate 50 having a plurality of nozzles 51, a frame member 60 as a structural part, and an FPC 70.

[0010] The piezoelectric member 20 alternately includes drive piezoelectric elements 23 and auxiliary piezoelectric elements 24 as a plurality of piezoelectric elements. The piezoelectric member 20 is divided into a plurality on one side by a plurality of grooves 22. That is, one end side of the piezoelectric member 20 is divided into a plurality by forming grooves 22 by, for example, dicing, and the other end side is connected, and the drive piezoelectric elements 23 and the auxiliary piezoelectric elements 24 are alternately arranged in parallel with the grooves 22 interposed therebetween along the third direction indicated by X in the figure. The piezoelectric member 20 is disposed, for example, at one end of the base 10 in the first direction and joined to the base 10. The plurality of piezoelectric members are laminated with their thickness directions along the first direction and adhered to each other via an adhesive layer. Note that the piezoelectric member 20 is polarized in the manufacturing process.

[0011] As shown in FIG. 3, the drive piezoelectric element 23 and the auxiliary piezoelectric element 24 are, for example, laminated piezoelectric bodies, and include a plurality of piezoelectric layers 211 laminated along the first direction indicated by the Z direction in the figure, a dummy layer 212, internal electrodes 221 and 222 formed on the main surfaces of the respective piezoelectric layers, and external electrodes 223 and 224. As an example, the drive piezoelectric element 23 and the auxiliary piezoelectric element 24 have the same configuration.

[0012] The piezoelectric layer 211 is formed into a thin plate shape from a piezoelectric material such as a PZT (lead zirconate titanate) - based material or a lead - free KNN (sodium potassium niobate) - based material. A plurality of piezoelectric layers 211 are laminated in the thickness direction along the lamination direction and are adhered to each other via an adhesive layer.

[0013] The internal electrodes 221 and 222 are conductive films formed in a predetermined shape from a sinterable conductive material such as silver palladium. The internal electrodes 221 and 222 are formed in a predetermined region on the main surface of each piezoelectric layer 211. The internal electrodes 221 and 222 have different polarities. For example, one internal electrode 221 is formed in a region that reaches one end of the piezoelectric layer 211 in the second direction indicated by the Y - direction in the figure and does not reach the other end. The second direction is a direction orthogonal to the first direction which is the lamination direction. The other internal electrode 222 is formed in a region that does not reach one end of the piezoelectric layer 211 but reaches the other end in the second direction indicated by the Y - direction in the figure. The internal electrodes 221 and 222 are respectively connected to the external electrodes 223 and 224 formed on the side surfaces of the piezoelectric elements 23 and 24.

[0014] The external electrodes 223 and 224 are formed on the surfaces of the piezoelectric elements 23 and 24 and are configured by gathering the ends of the internal electrodes 221 and 222. For example, the external electrodes 223 and 224 are respectively formed on one end face and the other end face in the second direction orthogonal to the lamination direction. The external electrodes 223 and 224 are formed of Ni, Cr, Au, etc. by a known method such as a plating method or a sputtering method. The external electrode 223 and the external electrode 224 are, for example, of different polarities, and the external electrode 223 and the external electrode 224 are respectively arranged on different side portions. Alternatively, the external electrodes 223 and 224 may be routed in different regions on the same side portion.

[0015] 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 serving as the individual electrodes of the plurality of piezoelectric elements 23 and 24 have electrode layers divided by grooves and are arranged independently of each other. The external electrode 224 serving as the common electrode has electrode layers connected to each other in a region on the base side rather than in the grooves and is, for example, grounded.

[0016] The external electrode 223 serving as an individual electrode is connected to, for example, the FPC 70, and is connected to mounted components such as a driving IC via various wirings.

[0017] For example, the individual external electrodes 223 and 224 are connected to the driving circuit 1161 of the control unit 116 as a driving unit via a wiring and a driving IC, and are configured to be drivable under the control by a CPU (Central Processing Unit).

[0018] The dummy layer 212 is made of the same material as the piezoelectric layer 211. The dummy layer 212 has an electrode only on one side and does not deform because no electric field is applied thereto. That is, the dummy layer 212 does not function as a piezoelectric body, serves as a base for fixing the piezoelectric member 20 to the base 10, or serves as a grinding allowance for polishing to achieve accuracy during or after assembly.

[0019] As an example, each of the piezoelectric elements 23 and 24 has 50 or fewer layers of the piezoelectric layer 211, each layer having a thickness of 10 μm to 40 μm, and the product of the thickness and the total number of layers being less than 1000 μm.

[0020] Voltage is applied to the internal electrodes 221 and 222 via the external electrodes 223 and 224, causing the piezoelectric elements 23 and 24 to vibrate longitudinally along the stacking direction of the piezoelectric layer 211. The longitudinal vibration referred to here is, for example, "vibration in the thickness direction defined by the piezoelectric constant d33". In this embodiment, as shown in FIG. 1 as an example, a plurality of driving piezoelectric elements 23 arranged at intervals sandwich the diaphragm 30 and are arranged corresponding to the pressure chamber 31, and the remaining auxiliary piezoelectric elements 24 are arranged at positions facing the partition portion 42 with the diaphragm 30 interposed therebetween. Here, end faces 231, 241, and 601, which are the opposing surfaces on the diaphragm 30 side of the piezoelectric elements 23 and 24 constituting the vibrating portion and the frame member 60 serving as a non-vibrating portion arranged on the outer periphery of the piezoelectric member 20, are flush and arranged on the same plane in the Z direction, which is the height direction.

[0021] The diaphragm 30 is joined to one side in the stacking direction of the plurality of piezoelectric elements 23 and 24, that is, the surface on the nozzle plate 50 side. The diaphragm 30 includes, for example, a plate portion 301 configured to be deformable, a first convex portion 302 joined to the drive piezoelectric element 23 and the auxiliary piezoelectric element 24 of the piezoelectric member 20, and a second convex portion 303 joined to the frame 60.

[0022] The plate portion 301 is, for example, flat and arranged along a first direction in which the thickness direction is the stacking direction, and extends in a surface direction orthogonal to the first direction. The plate portion 301 is, for example, a metal plate, has a plurality of vibration sites facing each pressure chamber 31 and displaceable individually, and the plurality of vibration sites are integrally formed continuously. For example, the plate portion 301 is configured as a single flat plate, and the regions joined to the respective piezoelectric elements 23 and 24 constitute vibration sites that displace individually. The plate portion 301 is configured of, for example, a SUS plate, and the thickness dimension along the Z direction is configured to be about 5 μm to 15 μm. Note that, in the plate portion 301, folds or steps may be formed between the vibration sites and the adjacent sites or between the vibration sites adjacent to each other so that the plurality of vibration sites are easily displaceable.

[0023] The first convex portion 302 and the second convex portion 303 are formed on the main surface on the other side of the plate portion 301. The convex portions 302 and 303 are made of an insulating organic polymer material, for example, photosensitive polyimide. The first convex portion 302 is disposed opposite to the end faces 231 and 241 of the piezoelectric elements 23 and 24. That is, the first convex portion 302 is formed in a region facing the end faces 231 and 241 of the plurality of piezoelectric elements 23 and 24, and is an insulating layer having the same shape as the end faces 231 and 241 and a predetermined thickness. The second convex portion 303 is disposed opposite to the end face 601 of the frame 60. That is, the second convex portion 303 is formed in a region facing the end face 601 of the frame 60 on the main surface on the other side of the plate portion 301, and is an insulating layer having the same shape as the end face 601 and a predetermined thickness. The first convex portion 302 and the second convex portion 303 are formed on the other side surface of the plate portion 301 with the same thickness. That is, the end faces of the plurality of first convex portions 302 and second convex portions 303 are arranged side by side at the same height position. The first convex portion 302 and the second convex portion 303 are configured to have a thickness dimension smaller than that of the plate portion 301. For example, the convex portions 302 and 303 are formed with a uniform film thickness on the main surface on the other side of the plate portion 301, which is opposite to the surface on the pressure chamber 31 side, and are formed into the same shape as the end faces 231 and 241 of the piezoelectric elements 23 and 24 and the end face 601 of the frame 60 by exposure processing and development processing. The thickness of the convex portions 302 and 303 is configured to be 5 μm or less.

[0024] For example, the first convex portion 302 disposed opposite to the pressure chamber 31 is configured to have a width dimension along the first direction smaller than that of the end face 231 of the piezoelectric element 23. Note that the first convex portion 302 facing the pressure chamber 31 and the second convex portion 303 disposed opposite to the frame 60 may have the same dimensions as the opposing end faces 241 and 601, or may be configured to be smaller. As an example, in the present embodiment, the end face of the first convex portion 302 is configured to have a dimension in the first direction smaller than that of the opposing end faces 231 and 241, and the second convex portion 303 is formed to have the same size as the end face 601.

[0025] The diaphragm 30 is deformed by the displacement of the portion disposed opposite to the driving piezoelectric element 23 due to the extension and compression of the driving piezoelectric element 23.

[0026] The diaphragm 30 is joined to the end faces 231 and 241 on one side of the piezoelectric elements 23 and 24 and the end face 601 of the frame member 60. As an example, in the present embodiment, regions at both ends in the second direction on the main surface on one side in the first direction of the diaphragm 30 are joined to the manifold 40. In the central portion of the inkjet head 1 in the second direction, a pressure chamber 31 and a guide flow path 34 capable of accommodating ink are formed between the diaphragm 30 and the manifold 40. A region on one end side of the main surface on the other side in the first direction of the diaphragm 30 is joined to the piezoelectric elements 23 and 24 via the first convex portion 302, and a predetermined region on the other end side in the second direction is joined to the end face 601 of the frame 60 via the second convex portion 303. For example, the first convex portion 302 and the second convex portion 303 are adhered to the end faces 231 and 241 of the piezoelectric elements 23 and 24 and the end face 601 of the frame 60. Note that the end faces 231 and 241 of the piezoelectric elements 23 and 24 and the end face 601 of the frame 60 may be subjected to a polishing process so as to be flush before joining the diaphragm 30.

[0027] In the present embodiment, a common chamber 32 capable of accommodating ink is formed between a part of the plate portion 301 of the diaphragm 30 on the other side in the first direction and the frame 60. That is, one side of the diaphragm 30 faces the piezoelectric elements 23 and 24, the frame 60, and the common chamber 32, respectively, and the other side faces the pressure chamber 31, the partition portion 42, and the guide flow path 34, respectively.

[0028] The diaphragm 30 has an opening 33 that penetrates in the thickness direction and communicates the pressure chamber 31 and the common chamber 32. The pressure chamber 31 is formed on one side of the diaphragm 30 in the first direction, and the common chamber 32 is formed on the other side of the diaphragm 30 in the first direction. The common chamber 32 extends in the third direction and communicates with a plurality of pressure chambers 31 arranged in the third direction. The diaphragm 30 changes the volume of the pressure chamber 31 by deforming as the piezoelectric elements 23 and 24 deform.

[0029] The manifold 40 is joined to one side of the diaphragm 30. The manifold 40 is disposed between the nozzle plate 50 and the diaphragm 30 and has a plurality of pressure chambers 31 separated by partition walls 42, and a guide flow path 34 that extends in a second direction from the plurality of pressure chambers 31 toward the opening 33 and is separated by the partition walls 42, and a predetermined ink flow path 35 is formed. The manifold 40 includes a frame-shaped portion 41 joined to the outer edge portion of the diaphragm 30, a plurality of partition walls 42 that separate the plurality of ink flow paths 35, and a guide wall 43 that forms the guide flow path 34.

[0030] Also, the plurality of pressure chambers 31 arranged in parallel in the third direction are separated by the partition walls 42. That is, both sides of the pressure chamber 31 in the third direction are constituted by the partition walls 42. The plurality of pressure chambers 31 are formed on one side of the plate portion 301 of the diaphragm 30. Each pressure chamber 31 communicates with a nozzle 51 formed in the nozzle plate 50 disposed on one side in the first direction. Also, the opposite side of the nozzle plate 50 is blocked by the diaphragm 30.

[0031] The plurality of pressure chambers 31 communicate with a common chamber 32 via the guide flow path 34 and the opening 33. The pressure chamber 31 holds the liquid supplied from the common chamber 32 via the guide flow path 34, and by deforming due to the vibration of the diaphragm 30 that forms a part of the pressure chamber 31, the liquid is ejected from the nozzle 51.

[0032] The partition wall 42 is a wall member that separates between the plurality of pressure chambers 31 arranged in the third direction, separates between the plurality of guide flow paths 34 arranged in the third direction, and constitutes both side portions of the pressure chamber 31 and the guide flow path 34. The partition wall 42 is disposed opposite to the auxiliary piezoelectric element 24 via the diaphragm 30 and is supported by the auxiliary piezoelectric element 24.

[0033] The nozzle plate 50 is formed of 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 manifold 40 so as to cover the opening on one side of the pressure chamber 31. A plurality of nozzles 51 penetrating in the thickness direction are formed in the nozzle plate 50. The nozzles 51 are arranged along the third direction to form a nozzle row. Each nozzle 51 is provided at a position corresponding to a plurality of pressure chambers 31, respectively.

[0034] The frame member 60 is disposed on the other side of the diaphragm 30 in the first direction. The frame member 60 is a structure joined to the diaphragm 30 together with the piezoelectric elements 23 and 24. The frame member 60 is provided in a direction orthogonal to the vibration direction of the diaphragm 30 of the piezoelectric elements 23 and 24, and is disposed around the piezoelectric member 20 in the present embodiment, for example. The frame member 60 constitutes the outer contour of the inkjet head 1. Further, the frame member 60 may form a liquid flow path inside. In the present embodiment, the frame member 60 is joined to the other side of the diaphragm 30 and forms a common chamber 32 between the frame member 60 and the diaphragm 30.

[0035] The common chamber 32 is formed inside the frame member 60 and communicates with the pressure chamber 31 through the opening 33 and the guide flow path 34 provided in the diaphragm 30.

[0036] The FPC 70 is connected to the individual electrodes. The FPC 70 is electrically and mechanically connected to the external electrodes 223 of the piezoelectric elements 23 and 24, for example.

[0037] In the inkjet head 1 configured as described above, a plurality of pressure chambers 31 communicating with the nozzles 51, a plurality of guide channels 34, and a common chamber 32 communicating with the plurality of pressure chambers 31 are formed by the nozzle plate 50, the frame member 60, the manifold 40, and the diaphragm 30. For example, the common chamber 32 communicates with the cartridge, and ink is supplied to each pressure chamber 31 through the common chamber 32. All the piezoelectric elements 23, 24 are connected by wiring so that a voltage can be applied thereto. In the inkjet head 1, when the control unit 116 applies a driving voltage to the electrodes 221, 222 by the driving IC 1161, the driving piezoelectric element 23 to be driven vibrates in the stacking direction, that is, in the thickness direction of each piezoelectric layer 211. That is, the driving piezoelectric element 23 vibrates longitudinally.

[0038] Specifically, the control unit 116 applies a driving voltage to the internal electrodes 221, 222 of the driving piezoelectric element 23 to be driven, and selectively drives the driving piezoelectric element 23 to be driven. Then, by combining the deformation in the tensile direction and the deformation in the compression direction by the driving piezoelectric element 23 to be driven, the diaphragm 30 is deformed, and the volume of the pressure chamber 31 is changed, so that the liquid is guided from the common chamber 32 and discharged from the nozzle 51.

[0039] Hereinafter, an example of an inkjet recording apparatus 100 including the inkjet head 1 will be described with reference to FIG. 4. The inkjet recording apparatus 100 includes a housing 111, a medium supply unit 112, an image forming unit 113, a medium discharge unit 114, a transport device 115, and a control unit 116.

[0040] The inkjet recording apparatus 100 is a liquid discharge apparatus that performs an image forming process on a sheet P by discharging a liquid such as ink while transporting the sheet P as a printing medium to be discharged along a predetermined transport path A from the medium supply unit 112 through the image forming unit 113 to the medium discharge unit 114.

[0041] The housing 111 constitutes the outer shell of the inkjet recording apparatus 100. A discharge port for discharging the sheet P to the outside is provided at a predetermined position of the housing 111.

[0042] The medium supply unit 112 includes a plurality of paper feed cassettes and is configured to stack and hold a plurality of sheets of paper P of various sizes.

[0043] The medium discharge unit 114 includes a paper discharge tray configured to hold the paper P discharged from the discharge port.

[0044] The image forming unit 113 includes a support unit 117 that supports the paper P, and a plurality of head units 130 disposed opposite to the upper side of the support unit 117.

[0045] The support unit 117 includes a conveyance belt 118 provided in a loop shape in a predetermined region where image formation is performed, a support plate 119 that supports the conveyance belt 118 from the back side, and a plurality of belt rollers 120 provided on the back side of the conveyance belt 118.

[0046] During image formation, the support unit 117 supports the paper P on the holding surface which is the upper surface of the conveyance belt 118, and conveys the paper P to the downstream side by sending the conveyance belt 118 at a predetermined timing by the rotation of the belt roller 120.

[0047] The head unit 130 includes a plurality (4 colors) of inkjet heads 1, ink tanks 132 as liquid tanks respectively mounted on each inkjet head 1, a connection flow path 133 that connects the inkjet head 1 and the ink tank 132, and a supply pump 134.

[0048] In the present embodiment, there are provided four inkjet heads 1 of cyan, magenta, yellow, and black, and ink tanks 132 that store the inks of these respective colors. The ink tanks 132 are connected to the inkjet heads 1 by connection flow paths 133.

[0049] In addition, a negative pressure control device such as a pump (not shown) is connected to the ink tank 132. Then, corresponding to the head values of the inkjet head 1 and the ink tank 132, the negative pressure in the ink tank 132 is controlled by the negative pressure control device, so that the ink supplied to each discharge nozzle 28 of the inkjet head 1 forms a meniscus of a predetermined shape.

[0050] The supply pump 134 is a liquid feeding pump composed of, for example, a piezoelectric pump. The supply pump 134 is provided in the supply flow path. The supply pump 134 is connected to the drive circuit 1161 of the control unit 116 by wiring and is configured to be controllable under the control of a CPU (Central Processing Unit). The supply pump 134 supplies liquid to the inkjet head 1.

[0051] The conveyance device 115 conveys the paper P along a conveyance path A extending from the medium supply unit 112 through the image forming unit 113 to the medium discharge unit 114. The conveyance device 115 includes a plurality of pairs of guide plates 121 arranged along the conveyance path A and a plurality of conveyance rollers 122.

[0052] Each of the plurality of pairs of guide plates 121 includes a pair of plate members arranged to face each other with the conveyed paper P therebetween, and guides the paper P along the conveyance path A.

[0053] The conveyance roller 122 is driven to rotate under the control of the control unit 116, and sends the paper P downstream along the conveyance path A. In addition, sensors for detecting the conveyance state of the paper are arranged at various positions in the conveyance path A.

[0054] The control unit 116 includes a control circuit such as a CPU which is a controller, a ROM (Read Only Memory) for storing various programs, etc., a RAM (Random Access Memory) for temporarily storing various variable data and image data, etc., and an interface unit for inputting data from the outside and outputting data to the outside.

[0055] In the inkjet recording apparatus 100 configured as described above, when the control unit 116 detects a print instruction by the operation of the operation input unit at the interface, for example, it drives the conveyance device 115 to convey the paper P and outputs a print signal to the head unit 130 at a predetermined timing, thereby driving the inkjet head 1. As a discharge operation, the inkjet head 1 sends a drive signal to the drive IC by an image signal corresponding to the image data, applies a drive voltage to the internal electrodes 221 and 222, selectively drives the drive piezoelectric element 23 to be discharged, vibrates vertically in the stacking direction, changes the volume of the pressure chamber 31, discharges the ink from the nozzle 51, and forms an image on the paper P held on the conveyance belt 118. Further, 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.

[0056] Here, the drive operation for driving the inkjet head 1 will be described. The inkjet head 1 according to the present embodiment includes drive piezoelectric elements 23 disposed opposite to the pressure chamber 31, and these drive piezoelectric elements 23 are connected by wiring so that a voltage can be applied. The control unit 116 sends a drive signal to the drive IC by an image signal corresponding to the image data, applies a drive voltage to the internal electrodes 221 and 222 of the drive piezoelectric element 23 to be driven, and selectively deforms the drive piezoelectric element 23 to be driven. Then, by combining the deformation in the tensile direction and the deformation in the compressive direction of the diaphragm 30, the volume of the pressure chamber 31 is changed to discharge the liquid.

[0057] For example, the control unit 116 alternately performs a pulling operation and a compressing operation. In the inkjet head 1, when pulling to increase the internal volume of the target pressure chamber 31, the drive piezoelectric element 23 to be driven is contracted, and the drive piezoelectric elements outside the drive target are not deformed. Also, in the inkjet head 1, when compressing to decrease the internal volume of the target pressure chamber 31, the drive piezoelectric element 23 to be driven is extended, and the drive piezoelectric elements outside the drive target are not deformed.

[0058] According to the inkjet head 1 and the inkjet recording apparatus 100 according to the above-described embodiment, it is possible to ensure the positional accuracy while ensuring the insulation between the diaphragm 30 and the piezoelectric elements 23 and 24. That is, since the diaphragm 30 has insulating convex portions 302 and 303 at the portions joined to the piezoelectric elements 23 and 24 and the frame member 60, the insulation between the diaphragm 30 and the piezoelectric elements 23 and 24 can be ensured, and the positional accuracy of the joint surfaces of the plurality of members can be improved. Further, the convex portions 302 and 303 can be formed at low cost by using a resist process on the joint surface side of the plate portion 301 without using a special manufacturing method such as electroforming. Further, since the structure is provided with the convex portions 302 and 303 corresponding to each of the piezoelectric elements 23 and 24, the diaphragm 30 can be easily deformed for each pressure chamber 31, and the vibration of the piezoelectric element 23 can be accurately transmitted independently for each pressure chamber 31. Also, in the above embodiment, by forming the convex portions 302 and 303 using polyimide having higher strength than the electroformed film, it is possible to maintain the strength while making the diaphragm 30 thinner, and by bringing the pressure chamber 31 closer to the piezoelectric elements 23 and 24, the vibration of the drive unit can be efficiently transmitted to the liquid chamber. In the above embodiment, the convex portions 302 and 303 made of a photosensitive resin material softer than the plate portion 301 are made thinner than the plate portion 301, so that the rigidity can be maintained. Therefore, the vibration of the piezoelectric element 23 can be transmitted to the pressure chamber 31, and the diaphragm 30 having insulating properties can be realized.

[0059] Also, for example, when forming a resin layer only on the part facing the piezoelectric element, it becomes difficult to ensure the height accuracy with peripheral members, which may cause poor adhesion. However, in the inkjet head 1 according to the above embodiment, in addition to the parts facing the piezoelectric elements 23 and 24, convex portions 302 and 303 having the same thickness are formed on the parts facing the frame member 60, which is a structure separate from the piezoelectric elements 23 and 24. Thereby, it becomes easy to form the plurality of convex portions 302 and 303 on the same height plane, and the adhesion accuracy can also be improved. Further, according to the above embodiment, by making the convex portions 302 and 303 insulating, it is easier to ensure the insulation between the piezoelectric elements 23 and 24 and the diaphragm 30 than in the case of being formed of, for example, a metal film. For example, in the case of being made of metal, it is necessary to form a convex portion at a portion narrower than the end face of the piezoelectric element so as not to reach the electrode formed at the end of the piezoelectric element, and fine processing is required. However, by making the convex portions 302 and 303 insulating, the required processing accuracy can be relaxed.

[0060] Note that the present invention is not limited to the above embodiment as it is, and at the implementation stage, the components can be modified and embodied without departing from the gist thereof.

[0061] For example, in the above embodiment, the frame member 60 is described as the structure, but it is not limited thereto. For example, the structure may be another member joined to the diaphragm 30 together with the piezoelectric elements 23 and 24.

[0062] For example, in the above embodiment, a configuration is adopted in which a plurality of layers of piezoelectric members are laminated and the piezoelectric element 23 is driven using the longitudinal vibration (d33) in the lamination direction, but it is not limited thereto. For example, it is applicable to a form in which the piezoelectric element is composed of a single-layer piezoelectric member, and is also applicable to a form driven by transverse vibration (d31).

[0063] In addition, the specific configurations of the piezoelectric elements 23 and 24, the shape of the flow path, and the configurations and positional relationships of various components including the manifold 40, the nozzle plate 50, and the frame member 60 are not limited to the examples described above and can be changed as appropriate. Also, the arrangement of the nozzles 51 and the pressure chambers 31 is not limited to the above. For example, two or more rows of nozzles 51 may be arranged. Also, a dummy chamber may be formed between a plurality of pressure chambers 31. Further, although an example in which the piezoelectric elements 23 and 24 have dummy layers 212 at both ends in the stacking direction has been shown, this is not limiting, and the dummy layer 212 may be provided only on one side of the piezoelectric elements 23 and 24, or the piezoelectric elements 23 and 24 may be configured without the dummy layer 212.

[0064] Also, the liquid to be ejected is not limited to the ink for printing, and for example, an apparatus that ejects a liquid containing conductive particles for forming a wiring pattern of a printed wiring board may be used.

[0065] In addition, in the above embodiment, an example in which the inkjet head 1 is used in a liquid ejection apparatus such as an inkjet recording apparatus has been shown, but this is not limiting, and for example, it can also be used in a 3D printer, an industrial manufacturing machine, and a medical application, and can be made smaller, lighter, and less costly.

[0066] According to at least one of the embodiments described above, it is possible to provide a liquid ejection head that can ensure positional accuracy while ensuring the insulation between the diaphragm and the piezoelectric element.

[0067] In addition, although some 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, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention and are included in the invention described in the claims and its equivalent scope. The following is an additional description of the invention equivalent to that described in the claims of the present application at the time of filing. (1) A plurality of piezoelectric elements made of a piezoelectric material, A structure provided side by side with the plurality of piezoelectric elements, A diaphragm having a plate portion, A plurality of first convex portions made of an organic polymer material formed at positions facing the piezoelectric elements on one side of the plate portion, A second convex portion made of an organic polymer material formed at a position facing the structure on one side of the plate portion, A plurality of pressure chambers formed on the other side of the plate portion and communicating with a plurality of nozzles for discharging liquid, A liquid ejection head comprising the above. (2) An electrode is formed on the surface of the piezoelectric element, The plurality of nozzles are arranged side by side in a first direction, The plurality of pressure chambers and piezoelectric elements are arranged side by side in the first direction, The liquid ejection head according to (1), wherein the piezoelectric element is a laminated piezoelectric body. (3) The liquid ejection head according to (1), wherein the first convex portion and the second convex portion are insulating layers made of a photosensitive resin material and formed by exposure. (4) The liquid ejection head according to (1), wherein the thickness dimension of the first convex portion and the second convex portion is smaller than the thickness dimension of the plate portion. (5) The structure is a frame member provided around the plurality of piezoelectric elements, The opposing surfaces of the first convex portion and the second convex portion facing the diaphragm are flush, the organic polymer material is polyimide, and the thickness of the first convex portion and the second convex portion is 5 μm or less. The liquid ejection head according to (1).

Explanation of Symbols

[0068] 1... Inkjet head, 10... Base, 20... Piezoelectric member, 22... Groove, 23... Driving piezoelectric element, 24... Auxiliary piezoelectric element, 30... Diaphragm, 31... Pressure chamber, 32... Common chamber, 33... Opening, 34... Guide flow path, 35... Ink flow path, 40... Manifold, 41... Frame-like portion, 42... Partition portion, 43... Guide wall, 50... Nozzle plate, 51... Nozzle, 60... Frame member, 70... Wiring board, 71... Base layer, 73... Solder plating layer, 74... Adhesive layer, 75... Insulating cover layer, 100... Inkjet recording apparatus, 111... Housing, 112... Medium supply unit, 113... Image forming unit, 114... Medium discharge unit, 115... Conveying device, 116... Control unit, 117... Support unit, 118... Conveying belt, 119... Support plate, 120... Belt roller, 121... Pair of guide plates, 122... Conveying roller, 130... Head unit, 132... Ink tank, 133... Connection flow path, 134... Supply pump, 201... Stacked piezoelectric body, 221, 222... Internal electrodes, 223, 224... External electrodes, 301... Plate portion, 302... First convex portion, 303... Second convex portion.

Claims

1. A plurality of piezoelectric elements, which are a laminated piezoelectric body including a plurality of piezoelectric members laminated along a lamination direction, A structure provided side by side with the plurality of piezoelectric elements, A plate portion disposed to face one side in the lamination direction of the plurality of piezoelectric elements; a plurality of first convex portions formed of an organic polymer material at positions facing the end faces on one side in the lamination direction of the piezoelectric elements in the plate portion; and a second convex portion formed of an organic polymer material at a position facing the end face on one side in the lamination direction of the piezoelectric elements in the structure in the plate portion. A diaphragm including: A plurality of pressure chambers formed on one side in the lamination direction of the plate portion and communicating with a plurality of nozzles for discharging liquid, Comprising, The liquid discharge head, wherein the first convex portion and the second convex portion are configured to have a thickness dimension along the lamination direction smaller than that of the plate portion.

2. An electrode is formed on the surface of the piezoelectric element, The plurality of nozzles are arranged side by side in a first direction different from the lamination direction, The liquid discharge head according to claim 1, wherein the plurality of pressure chambers and piezoelectric elements are arranged side by side in the first direction.

3. The liquid discharge head according to claim 1, wherein the first convex portion and the second convex portion are insulating layers formed of a photosensitive resin material and formed by exposure.

4. The liquid discharge head according to claim 1, wherein the thickness dimension along the lamination direction of the first convex portion and the second convex portion is smaller than the thickness dimension of the plate portion.

5. The structure is a frame member provided around the plurality of piezoelectric elements, The liquid discharge head according to claim 1, wherein the opposing surfaces of the first convex portion and the second convex portion facing the diaphragm are flush, the organic polymer material is polyimide, and the thicknesses of the first convex portion and the second convex portion are 5 μm or less.

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