Liquid discharge head and liquid discharge apparatus

Abstract

The present invention relates to a liquid ejecting head and a liquid ejecting apparatus that reduce stress generated at a boundary of a vibration plate and a pressure chamber substrate. The liquid ejecting head of the present invention includes a piezoelectric element (41) that generates energy, a vibration plate (35) that vibrates by the energy, and a pressure chamber substrate (34) that has a first face (3A) that is in contact with a portion of a bottom face of the vibration plate (35) and a first wall face (3Aa) that is continuous with the first face (3A), a recess (60) is provided on the bottom face of the vibration plate (35), the recess (60) has a bottom portion (61) and a curved portion (62) that surrounds the bottom portion (61), the curved portion (62) is provided between an end portion (61a) of the bottom portion (61) and an end portion of the recess (60) in a manner that spans therebetween, and forms a curved surface shape, a plurality of wall faces that constitute inner walls of a pressure chamber (Ca1) include a face of the recess (60) and the first wall face (3Aa), and an angle (θ1) formed by the first face (3A) and the first wall face (3Aa) is greater than 90 degrees and less than 180 degrees.

Description

Technical Field

[0001] This invention relates to a liquid ejector head and a liquid ejection device. Background Technology

[0002] A liquid ejector head for ejecting liquids such as ink from multiple nozzles has been proposed. For example, the liquid ejector head described in Patent Document 1 includes a pressure chamber forming substrate with a pressure chamber cavity formed therein, and a vibrating plate having a piezoelectric element. The vibrating plate faces the pressure chamber cavity. A recess consisting of a bottom surface and a curved surface is provided on the vibrating plate. The pressure chamber includes the recess of the vibrating plate and the pressure chamber cavity. The side surface of the pressure chamber includes the curved surface of the recess and the wall surface of the pressure forming substrate. The wall surface has a horizontal plane parallel to the bottom surface and a vertical plane perpendicular to the bottom surface. The vibrating plate and the pressure chamber forming substrate are in contact. The boundary between the vibrating plate and the pressure chamber forming substrate in the pressure chamber is located on the horizontal plane.

[0003] Typically, stress concentrates at the boundary between two components. Therefore, in the aforementioned liquid ejector head, stress concentration occurs at the boundary between the vibrating plate in the pressure chamber and the pressure chamber forming substrate. This stress concentration can sometimes cause cracks to form at the boundary. Consequently, conventional liquid ejector heads suffer from low durability.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2019-111738 Summary of the Invention

[0005] To address the above issues, a preferred embodiment of the present invention comprises: an energy generating element that generates energy for applying pressure to a liquid within a pressure chamber; a vibrating plate that vibrates using the energy; a pressure chamber substrate having a first surface in contact with a portion of the bottom surface of the vibrating plate and a first wall surface connected to the first surface; a recess provided on the bottom surface of the vibrating plate, the recess having a bottom and a curved portion surrounding the bottom, the curved portion being provided across the end of the bottom and the end of the recess and forming a curved shape; and a plurality of wall surfaces constituting the inner wall of the pressure chamber including the surface of the recess and the first wall surface, wherein the angle formed by the first surface and the first wall surface is greater than 90 degrees and less than 180 degrees. Attached Figure Description

[0006] Figure 1 This is a schematic diagram showing a partial structural example of the liquid ejection device according to the first embodiment.

[0007] Figure 2 This is a schematic diagram illustrating the flow channel structure inside a liquid ejector head.

[0008] Figure 3 for Figure 2 A cross-sectional view of line aa.

[0009] Figure 4 for Figure 2 A cross-sectional view of the bb line.

[0010] Figure 5 To be Figure 3 The enlarged cross-sectional view of a portion of pressure chamber Ca1 is shown.

[0011] Figure 6 A graph showing the relationship between the stress distribution of the bend 62 and the radius of curvature of the bend 62.

[0012] Figure 7 An explanatory diagram illustrating the configuration of the first wall 3Aa and the second wall 3Ab when the angles θ1 and θ2 are varied.

[0013] Figure 8 for Figure 6 An enlarged view of the curved portion 62 shown.

[0014] Figure 9 This is a schematic diagram illustrating the flow channel structure within the liquid ejector head according to the second embodiment.

[0015] Figure 10 for Figure 9 A cross-sectional view of line aa.

[0016] Figure 11 for Figure 9 A cross-sectional view of the bb line. Detailed Implementation

[0017] A: First Implementation Method

[0018] In the following description, the X, Y, and Z axes are assumed to be mutually orthogonal. The X, Y, and Z axes are common to all the figures illustrated in the following description. Figure 1 As illustrated, when observing from any point, one direction along the X-axis is labeled X1, and the opposite direction is labeled X2. X1 is equivalent to the "first direction." Similarly, from any point along the Y-axis, opposite directions are labeled Y1 and Y2. Furthermore, from any point along the Z-axis, opposite directions are labeled Z1 and Z2. Z1 is equivalent to the "second direction." Moreover, the XY plane, including the X and Y axes, is equivalent to the horizontal plane. The Z-axis is the vertical axis, and Z2 is equivalent to the downward direction of the vertical.

[0019] Figure 1This is a schematic diagram showing a partial structural example of the liquid ejection device 100 according to this embodiment. The liquid ejection device 100 is an inkjet printing apparatus that ejects droplets of liquid such as ink onto a medium 11. The medium 11 is, for example, printing paper. The medium 11 can also be any printing material such as resin film or cloth.

[0020] The liquid dispensing device 100 includes a liquid container 12. The liquid container 12 stores ink. The liquid container 12 can be, for example, a detachable box from the liquid dispensing device 100, a bag-shaped ink pouch formed of a flexible film, or an ink canister for refilling ink. Furthermore, the type of ink stored in the liquid container 12 is arbitrary.

[0021] like Figure 1 As shown, the liquid dispensing device 100 includes a control unit 21, a conveying mechanism 22, a moving mechanism 23, and a liquid dispensing head 24. The control unit 21 includes processing circuits such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array) and storage circuits such as semiconductor memory, and controls the various elements of the liquid dispensing device 100.

[0022] The conveying mechanism 22 conveys the medium 11 along the Y-axis under the control of the control unit 21. The moving mechanism 23 reciprocates the liquid nozzle 24 along the X-axis under the control of the control unit 21. The moving mechanism 23 has a generally box-shaped conveyor body 231 that houses the liquid nozzle 24, and a seamless conveyor belt 232 to which the conveyor body 231 is fixed. In addition, in this embodiment, a structure in which multiple liquid nozzles 24 are mounted on the conveyor body 231, and a structure in which the liquid container 12 is mounted on the conveyor body 231 together with the liquid nozzles 24, can be adopted.

[0023] The liquid ejector head 24, under the control of the control unit 21, ejects ink supplied from the liquid container 12 from each of a plurality of nozzles onto the medium 11. The ink is ejected onto the medium 11 by the liquid ejector head 24 in parallel with the repetitive reciprocating conveying of the medium 11 by the conveying mechanism 22 and the conveyor body 231, thereby forming an image on the surface of the medium 11.

[0024] Figure 2 This is a schematic diagram showing the flow channel structure within the liquid nozzle 24 when viewed along the Z-axis. (See diagram for reference.) Figure 2As shown, multiple nozzles Na and multiple nozzles Nb are formed on the surface of the liquid ejector head 24 opposite to the medium 11. The multiple nozzles Na and multiple nozzles Nb are arranged along the Y-axis. Each of the multiple nozzles Na and multiple nozzles Nb ejects ink in the Z-axis direction. Therefore, the Z-axis corresponds to the direction in which ink is ejected from each of the multiple nozzles Na and multiple nozzles Nb.

[0025] like Figure 2 As shown, multiple nozzles Na constitute a first nozzle array La, and multiple nozzles Nb constitute a second nozzle array Lb. The first nozzle array La is a collection of multiple nozzles Na arranged in a straight line along the Y-axis. Similarly, the second nozzle array Lb is a collection of multiple nozzles Nb arranged in a straight line along the Y-axis. Figure 2 As shown, the first nozzle array La and the second nozzle array Lb are arranged side-by-side at a predetermined interval in the X-axis direction. Furthermore, the positions of the nozzles Na in the Y-axis direction and the positions of the nozzles Nb in the Y-axis direction are different. Figure 2 As shown, multiple nozzles N, including nozzles Na and Nb, are arranged at a spacing θ. The spacing θ is the distance between the center of nozzle Na and the center of nozzle Nb in the Y-axis direction. In the following description, subscript a is added to the symbol of the element associated with nozzle Na of the first nozzle column La, and subscript b is added to the symbol of the element associated with nozzle Nb of the second nozzle column Lb. Furthermore, unless there is a specific need to distinguish between nozzle Na of the first nozzle column La and nozzle Nb of the second nozzle column Lb, they are simply referred to as "nozzle N". Additionally, nozzles Na and Nb are positioned at the same location in the Z-axis direction, and the first nozzle column La and the second nozzle column Lb can also be arranged in a straight line.

[0026] like Figure 2 As shown, an independent flow channel array 25 is provided in the liquid nozzle 24. The independent flow channel array 25 is a collection of multiple independent flow channels Pa and multiple independent flow channels Pb. Each of the multiple independent flow channels Pa extends in the X1 direction and corresponds to a different nozzle Na. Each of the multiple independent flow channels Pa is connected to a nozzle Na. Similarly, each of the multiple independent flow channels Pb extends in the X1 direction and corresponds to a different nozzle Nb. Each of the multiple independent flow channels Pb is connected to a nozzle Nb. The detailed structure of the independent flow channels Pa and Pb will be described later. Furthermore, in the following description, unless there is a specific need to distinguish between the independent flow channels Pa and Pb, they will simply be referred to as "independent flow channel P".

[0027] Independent flow channels Pa and Pb, which are face-to-face and adjacent in the Y-axis direction, are in a reversed relationship with the Z-axis as the center. Specifically, when independent flow channel Pa rotates 180° around the Z-axis, it becomes the same configuration as independent flow channel Pb, and when independent flow channel Pb rotates 180° around the Z-axis, it becomes the same configuration as independent flow channel Pa.

[0028] like Figure 2 As shown, the independent flow channel Pa has pressure chambers Ca1 and Ca2. Pressure chambers Ca1 and Ca2 within the independent flow channel Pa extend in the X1 direction. Ink ejected from nozzle Na, which communicates with the independent flow channel Pa, is stored in pressure chambers Ca1 and Ca2. When the pressure within pressure chambers Ca1 and Ca2 changes, ink is ejected from nozzle Na.

[0029] Similarly, the independent flow channel Pb has pressure chambers Cb1 and Cb2. Pressure chambers Cb1 and Cb2 of the independent flow channel Pb extend in the X1 direction. Ink ejected from the nozzle Nb, which is connected to the independent flow channel Pb, is stored in pressure chambers Cb1 and Cb2. When the pressure within pressure chambers Cb1 and Cb2 changes, ink is ejected from the nozzle Nb.

[0030] Furthermore, in the following description, unless there is a specific need to distinguish between the pressure chambers Ca1 and Ca2 corresponding to the first nozzle line La and the pressure chambers Cb1 and Cb2 corresponding to the second nozzle line Lb, they will simply be referred to as "pressure chamber C".

[0031] like Figure 2 As shown, a first common liquid chamber R1 and a second common liquid chamber R2 are provided in the liquid nozzle 24. The first common liquid chamber R1 and the second common liquid chamber R2 each extend in the Y-axis direction, covering the entire area where the plurality of nozzles N are distributed. In a top view taken from the Z1 direction, the independent flow channel row 25 and the plurality of nozzles N are located between the first common liquid chamber R1 and the second common liquid chamber R2.

[0032] Multiple independent flow channels P are connected to a first common liquid chamber R1. Specifically, the end E1 of each independent flow channel P in the X2 direction is connected to the first common liquid chamber R1. Similarly, multiple independent flow channels P are connected to a second common liquid chamber R2. Specifically, the end E2 of each independent flow channel P in the X1 direction is connected to the second common liquid chamber R2. In the liquid ejector head 24, each independent flow channel P connects the first common liquid chamber R1 and the second common liquid chamber R2. As a result, ink supplied from the first common liquid chamber R1 to each independent flow channel P is ejected from the nozzle N. Furthermore, ink from the first common liquid chamber R1 that is not ejected from the nozzle N is discharged into the second common liquid chamber R2.

[0033] like Figure 2 As shown, the liquid ejector head 24 has a circulation mechanism 26. The circulation mechanism 26 is a mechanism that circulates the ink discharged from each individual flow channel P to the second common liquid chamber R2 back into the first common liquid chamber R1. The circulation mechanism 26 includes a first supply pump 261, a second supply pump 262, a storage container 263, a circulation flow channel 264, and a supply flow channel 265.

[0034] The first supply pump 261 is a pump that supplies ink stored in the liquid container 12 to the storage container 263. The storage container 263 is a secondary tank that temporarily stores the ink supplied from the liquid container 12.

[0035] The circulation channel 264 is a channel that connects the second common liquid chamber R2 and the storage container 263, and ink is discharged from the discharge channel Ra2 and the discharge channel Rb2 (described later) through the second common liquid chamber R2.

[0036] In the storage container 263, in addition to the ink stored in the liquid container 12 being supplied from the first supply pump 261, ink discharged from each individual channel P to the second common liquid chamber R2 is also supplied via the circulation channel 264.

[0037] The second supply pump 262 is a pump that delivers ink stored in the storage container 263. The ink delivered from the second supply pump 262 is supplied to the first common liquid chamber R1 via the supply channel 265.

[0038] The independent flow channel row 25 has multiple independent flow channels P, each having multiple independent flow channels Pa and multiple independent flow channels Pb. Each independent flow channel Pa is connected to a nozzle Na in the first nozzle row La. Each independent flow channel Pb is connected to a nozzle Nb in the second nozzle row Lb. The independent flow channels Pa and Pb are arranged alternately along the Y-axis. Thus, the independent flow channels Pa and Pb form a structure that is face-to-face, i.e., adjacent to each other, in the Y-axis direction.

[0039] like Figure 2 As shown, the independent flow channel Pa has a nozzle flow channel Nfa. The nozzle flow channel Nfa extends in the X1 direction and, as shown in the figure, is located between pressure chambers Ca1 and Ca2 when viewed in the Z1 direction. The nozzle flow channel Nfa communicates with both pressure chambers Ca1 and Ca2 and is provided with a nozzle Na that ejects ink supplied from pressure chamber Ca1.

[0040] like Figure 2 As shown, the independent flow channel Pb has a nozzle flow channel Nfb. The nozzle flow channel Nfb extends in the X1 direction and, as shown in the figure, is located between pressure chambers Cb1 and Cb2 when viewed in the Z1 direction, that is, when viewed from the Z1 direction. The nozzle flow channel Nfb communicates with pressure chambers Cb1 and Cb2 and is provided with a nozzle Nb that ejects ink supplied from pressure chamber Cb1.

[0041] Nozzle channels Nfa and Nfb are arranged in a straight line along the Y-axis. Nozzle channels Nfa and Nfb are arranged side by side with a predetermined interval in the Y-axis direction. Nozzle channels Nfa and Nfb that face each other in the Y-axis direction are in a reversed relationship about the Z-axis.

[0042] In the liquid ejector head 24 of this embodiment, as Figure 2 As shown, multiple pressure chambers Ca1 corresponding to different nozzles Na of the first nozzle array La, and multiple pressure chambers Cb1 corresponding to different nozzles Nb of the second nozzle array Lb, are arranged in a straight line along the Y-axis. Similarly, multiple pressure chambers Ca2 corresponding to different nozzles Na of the first nozzle array La, and multiple pressure chambers Cb2 corresponding to different nozzles Nb of the second nozzle array Lb, are arranged in a straight line along the Y-axis. The arrangement consisting of multiple pressure chambers Ca1 and multiple pressure chambers Cb1, and the arrangement consisting of multiple pressure chambers Ca2 and multiple pressure chambers Cb2, are arranged side by side in the X-axis direction at predetermined intervals. The positions of each pressure chamber Ca1 and each pressure chamber Ca2 in the Y-axis direction are the same here, but they may also be different. Similarly, the positions of each pressure chamber Cb1 and each pressure chamber Cb2 in the Y-axis direction are also the same here, but they may also be different.

[0043] The liquid ejector head 24 circulates the ink during ejection, thereby suppressing thickening or sedimentation of ink near nozzles Na and Nb and preventing deterioration of ink ejection characteristics. This allows for a relatively stable ink ejection characteristic, suppressing deviations and improving ink ejection quality. Furthermore, the aforementioned "ejection characteristics" refer to, for example, the ink ejection volume or ejection speed.

[0044] Next, the detailed structure of the liquid ejector head 24 will be described. Figure 3 for Figure 2 A cross-sectional view of line aa. Figure 4 for Figure 2 A cross-sectional view along the bb line. Figure 3 The image shows a cross-section through the independent flow channel Pa. Figure 4 The image shows a cross-section through the independent flow channel Pb.

[0045] like Figure 3 as well as Figure 4 As shown, the liquid ejector head 24 has a flow channel structure 30, multiple piezoelectric elements 41, a housing portion 42, a protective substrate 43, and a wiring substrate 44. The flow channel structure 30 is a structure that forms a flow channel having a first common liquid chamber R1, a second common liquid chamber R2, multiple independent flow channels P, and multiple nozzles N.

[0046] The flow channel structure 30 is a structure in which a nozzle plate 31, a flow channel substrate 33, a pressure chamber substrate 34, and a vibrating plate 35 are stacked sequentially in the Z1 direction. These elements constituting the flow channel structure 30 are manufactured by processing a single-crystal substrate using, for example, a general processing method for manufacturing semiconductors. The vibrating plate 35 extends in the X1 direction.

[0047] Multiple nozzles N are formed in the nozzle plate 31. Each nozzle N is a cylindrical through-hole through which ink passes. Figure 3 as well as Figure 4 As shown, the nozzle plate 31 is a plate-shaped member having a surface Fa1 facing the Z2 direction and a surface Fa2 facing the Z1 direction. The flow channel substrate 33 is a plate-shaped member having a surface Fc1 facing the Z2 direction and a surface Fc2 facing the Z1 direction.

[0048] The various elements constituting the flow channel structure 30 are formed into rectangular shapes and are joined together with each other using, for example, an adhesive. For example, the surface Fa2 of the nozzle plate 31 is joined to the surface Fc1 of the flow channel substrate 33, and the surface Fc2 of the flow channel substrate 33 is joined to the surface Fd1 of the pressure chamber substrate 34. The surface Fd2 of the pressure chamber substrate 34 is joined to the surface Fe1 of the vibrating plate 35. The surface Fe1 of the vibrating plate 35 is an example of the bottom surface of the vibrating plate.

[0049] Spaces O12 and O22 are formed in the flow channel substrate 33. Spaces O12 and O22 are elongated openings in the Y-axis direction. A vibration absorber 361 that closes space O12 and a vibration absorber 362 that closes space O22 are provided on the surface Fc1 of the flow channel substrate 33. Vibration absorbers 361 and 362 are layered components formed of an elastic material.

[0050] The housing 42 is a shell for storing ink. The housing 42 is joined to the surface Fc2 of the flow channel substrate 33. Within the housing 42, a space O13 communicating with space O12 and a space O23 communicating with space O22 are formed. Spaces O13 and O23 are elongated spaces in the Y-axis direction. Spaces O12 and O13 are interconnected to form a first common liquid chamber R1. Similarly, spaces O22 and O23 are interconnected to form a second common liquid chamber R2. A vibration absorber 361 forms the wall of the first common liquid chamber R1 and absorbs pressure fluctuations of the ink within the first common liquid chamber R1. A vibration absorber 362 forms the wall of the second common liquid chamber R2 and absorbs pressure fluctuations of the ink within the second common liquid chamber R2.

[0051] A supply port 421 and a discharge port 422 are formed on the housing portion 42. The supply port 421 is a pipe communicating with the first common liquid chamber R1 and connected to the supply flow channel 265 of the circulation mechanism 26. Ink supplied from the second supply pump 262 to the supply flow channel 265 is supplied to the first common liquid chamber R1 through the supply port 421. On the other hand, the discharge port 422 is a pipe communicating with the second common liquid chamber R2 and connected to the circulation flow channel 264 of the circulation mechanism 26. Ink in the second common liquid chamber R2 is supplied to the circulation flow channel 264 through the discharge port 422.

[0052] Pressure chambers Ca1 and Ca2, and pressure chambers Cb1 and Cb2 are provided in the pressure chamber substrate 34. Each pressure chamber C is the interval between the surface Fc2 of the flow channel substrate 33 and the vibrating plate 35. In a top view taken from the Z1 direction, each pressure chamber C is formed as an elongated strip along the X-axis and extends in the X1 direction.

[0053] The vibrating plate 35 is a plate-shaped component capable of elastic vibration. The vibrating plate 35 is, for example, at least a portion of which is formed of silicon oxide (SiO2). More specifically, it is constructed by stacking a first layer of silicon oxide (SiO2) functioning as an elastic layer and a second layer of zirconium oxide (ZrO2) functioning as an insulating layer. Alternatively, a portion in the thickness direction can be selectively removed from the plate-shaped component of a predetermined thickness, corresponding to the pressure chamber C, thereby integrally forming the vibrating plate 35 and the pressure chamber substrate 34. Furthermore, the vibrating plate 35 can also be formed as a single layer.

[0054] On the surface Fe2 of the vibrating plate 35, a plurality of piezoelectric elements 41 corresponding to different pressure chambers C are provided. When viewed from above in the Z1 direction, the piezoelectric elements 41 corresponding to each pressure chamber C overlap with the pressure chamber C. Specifically, each piezoelectric element 41 is constructed by stacking a first electrode and a second electrode that are opposed to each other, and a piezoelectric layer formed between the two electrodes. Each piezoelectric element 41 is an energy generating element that generates energy to apply pressure to the ink within the pressure chamber C. Furthermore, the vibrating plate 35 vibrates using the energy generated by the piezoelectric elements 41. Specifically, the piezoelectric elements 41 deform themselves by receiving a drive signal, thereby causing the vibrating plate 35 to vibrate. When the vibrating plate 35 vibrates, the pressure chamber C expands and contracts. Through the expansion and contraction of the pressure chamber C, pressure is applied to the ink from the pressure chamber C. As a result, the ink is ejected from the nozzle N.

[0055] The protective substrate 43 is a plate-shaped component disposed on the surface Fe2 of the vibrating plate 35, protecting the plurality of piezoelectric elements 41 and reinforcing the mechanical strength of the vibrating plate 35. The plurality of piezoelectric elements 41 are housed between the protective substrate 43 and the vibrating plate 35. Furthermore, a wiring substrate 44 is mounted on the surface Fe2 of the vibrating plate 35. The wiring substrate 44 is a mounting component for electrically connecting the control unit 21 and the liquid ejector head 24. For example, a flexible wiring substrate 44 such as an FPC (Flexible Printed Circuit) or an FFC (Flexible Flat Cable) is preferably used. A drive circuit 45 for supplying drive signals to each piezoelectric element 41 is mounted on the wiring substrate 44. The drive circuit 45 functions as a control unit for controlling the ejection action from the liquid ejector head 24.

[0056] Next, the detailed structure of pressure chamber Ca1 will be described. Additionally, Figure 3 The pressure chamber Ca2 shown Figure 4 The pressure chambers Cb1 and Cb2 shown are constructed in the same manner as pressure chamber Ca1. Figure 5 For, will Figure 3 The image shows an enlarged cross-sectional view of a portion of pressure chamber Ca1. (See image.) Figure 5 As shown, a recess 60 is provided on the surface Fe1 of the vibrating plate 35. The recess 60 has a bottom 61 and a curved portion 62. The bottom 61 is the base of the recess 60. Therefore, when the recess 60 is viewed in the Y1 direction, the bottom 61 is located at the furthest position in the Z1 direction. The bottom 61 is, for example, a plane parallel to the XY plane. The curved portion 62 surrounds the bottom 61. The curved portion 62 is provided such that it spans between the end 61a of the bottom 61 and the end 60a of the recess 60. In the following description, the end 60a of the recess 60 is referred to as the first end 60a, and the end 61a of the bottom 61 is referred to as the second end 61a. When the curved portion 62 is cut by multiple planes parallel to the XY plane, the cross-sectional area of ​​the multiple cut planes increases toward the Z2 direction. The curved portion 62 forms a curved surface shape. The width of the curved portion 62 in the Z1 direction is Wz, and the width of the curved portion 62 in the X1 direction is Wx. The curved surface of the curved portion 62 is, for example, an arc shape. When the shape of the curved portion 62 is an arc shape, the width Wx and the width Wz are equal. The curved surface of the curved portion 62 is not limited to an arc shape.

[0057] The surface Fd2 of the pressure chamber substrate 34 has a first surface 3A that is in contact with a part of the surface Fe1, which is the bottom surface of the vibrating plate 35, and a second surface 3B that is in contact with a part of the surface Fe1, which is the bottom surface of the vibrating plate 35. The pressure chamber substrate 34 has a first wall surface 3Aa connected to the first surface 3Aa and a second wall surface 3Ab connected to the first wall surface 3Aa. Furthermore, the pressure chamber substrate 34 has a third wall surface 3Ba connected to the second surface 3B and a fourth wall surface 3Bb connected to the third wall surface 3Ba. The plurality of wall surfaces constituting the inner wall of the pressure chamber Ca1 include the surface of the recess 60, the first wall surface 3Aa, the second wall surface 3Ab, the third wall surface 3Ba, and the fourth wall surface 3Bb. The third wall surface 3Ba faces the first wall surface 3Aa in the X1 direction. Furthermore, the fourth wall surface 3Bb faces the second wall surface 3Ab in the X1 direction.

[0058] In this example, when the recess 60 is viewed in the Z1 direction, the position x1 of the second end 61a in the X1 direction is substantially the same as the position x2 of the second wall surface 3Ab in the X1 direction. The position x1 of the second end 61a is the position of the boundary between the bottom 61 and the curved portion 62 in the X1 direction.

[0059] Furthermore, the position z2 of the second face 3B in the Z1 direction is basically the same as the position z1 of the first face 3A in the Z1 direction.

[0060] The angle formed by the first surface 3A and the first wall surface 3Aa is θ1, and the angle formed by the first wall surface 3Aa and the second wall surface 3Ab is θ2. Furthermore, the angle formed by the second surface 3B and the third wall surface 3Ba is θ3, and the angle formed by the third wall surface 3Ba and the fourth wall surface 3Bb is θ4. In the following description, the angle formed by one surface of a component and another surface refers to the angle formed by the interior of the component, not the exterior of the component.

[0061] When a drive signal is applied to the piezoelectric element 41, the vibrating plate 35 will displace along the Z-axis. Stress is generated due to this displacement of the vibrating plate 35. The simulation results are explained regarding the relationship between the stress distribution and the radius of curvature of the bent portion 62. In this simulation, a tantalum oxide (TaO) layer with a thickness of 30 nm is assumed. X A vibrating plate 35 is covered with silicon oxide (SiO2). Furthermore, the angle θ1 is set to 180 degrees. In this case, the first surface 3A and the first wall surface 3Aa are contained within the same plane. Moreover, it is assumed that the curved surface of the bent portion 62 is an ideal arc shape. Figure 6 The simulation results are shown in [the image]. Figure 6 In the diagram, the vertical axis represents the maximum principal stress, and the horizontal axis represents the radius of curvature. Point P1 is the location where the principal stress is maximum in the plane facing the pressure chamber Ca1. Point P2 is the location where the principal stress is maximum at the center of the tantalum oxide thickness. Point P3 is the location where the principal stress is maximum in silicon oxide.

[0062] like Figure 6 As shown, when the radius of curvature is less than 150 nm, stress concentrates at the first end 60a. Furthermore, it is known that when the radius of curvature exceeds 150 nm and increases, the stress concentration point shifts from the first end 60a towards the center of the arc of the curved portion 62.

[0063] If the radius of curvature is increased, the stress at the first end 60a will be reduced. To increase the radius of curvature, the thickness of the vibrating plate 35 in the film thickness direction needs to be increased; in other words, the width of the vibrating plate 35 in the Z1 direction needs to be increased.

[0064] The vibrating plate 35 can be manufactured through various manufacturing processes. When the width of the vibrating plate 35 in the Z1 direction is increased during a certain manufacturing process, the compressive stress of the silicon oxide constituting the vibrating plate 35 will increase the amount of wafer warpage. Therefore, depending on the type of manufacturing process, wafer warpage can make manufacturing the vibrating plate 35 difficult. Alternatively, depending on the type of manufacturing process, additional steps may be required to suppress wafer warpage. Therefore, depending on the type of manufacturing process, to reduce the thickness of the vibrating plate 35 in the film thickness direction, it is desirable to set the radius of curvature to 150 nm or less. In this case, it is preferable to suppress stress concentration at the first end 60a.

[0065] Return to the instructions Figure 5 In this embodiment, there is a first wall surface 3Aa that is inclined relative to the first surface 3A, and a third wall surface 3Ba that is inclined relative to the second surface 3B. Specifically, the angle θ1 formed by the first surface 3A and the first wall surface 3Aa is given by Equation 1 shown below.

[0066] 90<θ1<180…Equation 1

[0067] That is, the angle θ1 is greater than 90 degrees and less than 180 degrees.

[0068] θ2=180-{180-90-(180-θ1)}=270-θ1...Equation 2

[0069] That is, the angle θ2 formed by the first wall surface 3Aa and the second wall surface 3Ab is substantially equal to the angle obtained by subtracting the angle θ1 formed by the first surface 3Aa and the first wall surface 3Aa from 270 degrees. In this specification, "substantially equal" means including manufacturing errors.

[0070] Equation 3 is derived from Equations 1 and 2.

[0071] 90<θ2<180…Equation 3

[0072] That is, the angle θ2 is greater than 90 degrees and less than 180 degrees.

[0073] Next, the angle θ3 formed by the second surface 3B and the third wall surface 3Ba is given by Equation 4 as shown below.

[0074] 90 < θ3 < 180… Equation 4

[0075] That is, angle θ3 is greater than 90 degrees and less than 180 degrees.

[0076] Furthermore, the angle θ4 formed by the third wall 3Ba and the fourth wall 3Bb is given by Equation 5 as shown below.

[0077] θ4=180-{180-90-(180-θ3)}=270-θ3...Equation 5

[0078] That is, the angle θ4 formed by the third wall 3Ba and the fourth wall 3Bb is approximately equal to the angle obtained by subtracting the angle θ3 formed by the second wall 3B and the third wall 3Ba from 270 degrees.

[0079] Equation 6 is derived from Equations 4 and 5.

[0080] 90 < θ4 < 180… Equation 6

[0081] That is, angle θ4 is greater than 90 degrees and less than 180 degrees.

[0082] By setting angles θ1, θ2, θ3, and θ4 in this way, the stress in the first end 60a is reduced compared to the case where θ1 = θ3 = 180°.

[0083] When the liquid ejector head 24 is in operation, air bubbles may sometimes flow in from the nozzle Na. When these air bubbles mix into the ink in the pressure chamber Ca1, the plasticity increases compared to the case where no air bubbles are mixed into the pressure chamber Ca1. Therefore, even if the same drive signal is applied to the piezoelectric element 41 as it would be in the case where no air bubbles are mixed into the pressure chamber Ca1, the displacement of the vibrating plate 35 will increase. Furthermore, with the increase in plasticity, the inherent vibration frequency, which is determined by the shape of the piezoelectric element 41, the vibrating plate 35, the pressure chamber Ca1, and the viscosity of the ink, will change. Due to the change in the inherent vibration frequency, the vibrating plate 35 may sometimes resonate, and the displacement of the vibrating plate 35 will increase. When the displacement of the vibrating plate 35 increases, the stress in the first end 60a increases. Therefore, when air bubbles are mixed into the ink in the pressure chamber Ca1, the possibility of cracks forming at the first end 60a increases. Preferably, the air bubbles mixed into the pressure chamber Ca1 are rapidly expelled from the pressure chamber Ca1. However, when the angle θ1 is 180 degrees, when an air bubble enters the bend 62, the air bubble becomes more likely to get stuck in the bend 62.

[0084] As described above, the first wall surface 3Aa is inclined relative to the first surface 3A, and the third wall surface 3Ba is inclined relative to the second surface 3B. Even if an air bubble enters the bend 62, the bubble will easily detach from the bend 62. Moreover, the air bubble detached from the bend 62 will be discharged from the pressure chamber Ca1 as the ink circulates. Therefore, from the viewpoint of preventing air bubbles from being trapped in the bend 62, by making the first wall surface 3Aa inclined relative to the first surface 3A and the third wall surface 3Ba inclined relative to the second surface 3B, the stress in the first end 60a can be reduced.

[0085] As explained above, by providing a first wall surface 3Aa inclined relative to the first surface 3A and a third wall surface 3Ba inclined relative to the second surface 3B, the stress at the first end 60a is reduced. As a result, cracking at the first end 60a can be suppressed, and the durability of the liquid ejector head 24 is improved.

[0086] Furthermore, since the stress at the first end 60a can be reduced, the radius of curvature of the curved surface of the bent portion 62 can be set to 150 nm or less. By setting the radius of curvature of the surface in this way, the manufacturing of the vibrating plate 35 can be made easier.

[0087] Next, from the perspective of structural crosstalk related to pressure chamber C, angles θ1 and θ2 will be studied and discussed. Structural crosstalk related to pressure chamber C refers to the phenomenon that, in adjacent pressure chambers Ca1 and Cb1 along the Y-axis, vibration caused by pressure change in one pressure chamber C propagates to the other pressure chamber C, thereby reducing the ejection characteristics of the nozzle connected to the other pressure chamber C. Figure 7 This is an explanatory diagram schematically showing the configuration of the first wall 3Aa and the second wall 3Ab when the angles θ1 and θ2 are varied. Figure 7 The pressure chamber Ca1 shown is divided into pressure chamber Ca1 and adjacent pressure chamber Cb1 by pressure chamber substrate 34. In other words, pressure chamber substrate 34 functions as a sidewall that separates pressure chamber Ca1 and pressure chamber Cb1.

[0088] like Figure 7 As shown, when angle θ1 is gradually decreased, the position of the first wall 3Aa changes in the direction of arrow S. Since angles θ1 and θ2 have the relationship shown in Equation 2, when angle θ1 decreases, angle θ2 increases.

[0089] Furthermore, as the angle θ1 decreases, the cross-sectional area of ​​the pressure chamber substrate 34 decreases. As a result, the strength of the sidewalls between the pressure chambers Ca1 and Cb1, which are formed by the pressure chamber substrate 34, decreases. Since vibrations become easier to transmit when the strength of the sidewalls decreases, structural crosstalk increases. On the other hand, the smaller the angle θ1 and the larger the angle θ2, the smaller the stress in the first end 60a becomes.

[0090] Therefore, the stress at the first end 60a and the structural crosstalk are mutually exclusive.

[0091] From the viewpoint of tolerating the effects of structural crosstalk and the durability of the liquid nozzle 24 caused by stress at the first end 60a, it is preferable that the angle θ1 is less than 180 degrees and greater than 150 degrees. Furthermore, it is preferable that the angle θ2 is greater than 90 degrees and less than 120 degrees.

[0092] Furthermore, it is preferable that the magnitude of the stress at the first end 60a of the first surface 3A is equal to the magnitude of the stress at the first end 60a of the second surface 3B. This is because if the magnitudes of the stress at the first end 60a of the first surface 3A and the first end 60a of the second surface 3B are different, the likelihood of a crack forming at the first end 60a with the greater stress is higher. Therefore, it is preferable that angles θ1 and θ3 are substantially equal. Furthermore, it is preferable that angles θ2 and θ4 are substantially equal.

[0093] The curved surface shape of the bending portion 62, which is suitable for reducing stress at the first end 60a, will be further described below.

[0094] Figure 8 for, Figure 6 An enlarged view of the curved portion 62 shown. (See attached image.) Figure 8 As shown, preferably, the width Wz in the Z1 direction of the bent portion 62 is greater than the width Wx in the X1 direction of the bent portion 62. Figure 7 As shown, the bent portion 62 has a first portion 621 including a first end 60a and a second portion 622 including a second end 61a. That is, the first portion 621 includes the boundary between the pressure chamber substrate 34 and the bent portion 62. Furthermore, the second portion 622 includes the boundary between the bottom 61 and the bent portion 62. In this case, the degree of bending of the first portion 621 is greater than the degree of bending of the second portion 622. In other words, the radii of curvature of the bent portion 62 are not uniform; the radius of curvature of the first portion 621 is greater than the radius of curvature of the second portion 622. By defining the radii of curvature of the first portion 621 and the second portion 622 in this manner, the width Wz in the Z1 direction of the bent portion 62 is greater than the width Wx in the X1 direction of the bent portion 62.

[0095] The stress at the first end 60a is more significantly affected by the first portion 621 than that at the second portion 622. Therefore, compared to the case where the radius of curvature of the first portion 621 is smaller, the stress at the first end 60a is smaller when the radius of curvature of the first portion 621 is larger. Therefore, by making the radius of curvature of the first portion 621 smaller than that of the second portion 622, it is possible to reduce the stress at the first end 60a while simultaneously reducing the width Wz in the Z1 direction of the bent portion 62. This improves the durability of the liquid ejector head 24 and reduces the likelihood of problems caused by wafer warping.

[0096] Next, the relationship between the width Wz in the Z1 direction of the bent portion 62, the width Wx in the X1 direction of the bent portion 62, and the angle θ1 will be explained. The inventors of this application have confirmed through experiments that as long as the relationship shown in Table 1 below is maintained, the magnitude of the stress at the first end 60a can be reduced.

[0097] Table 1

[0098] Wx[nm] Wx[nm] θ1 50 106.7 169.8 100 184.5 170.0 150 254.2 170.3 200 319.1 170.5 250 380.6 170.7 300 439.6 170.9 400 496.5 171.1

[0099] Based on the above experiment, the following relationship exists between width Wx and width Wz, as shown in Equation 7.

[0100] Wz = 4.8541Wx -(-0.79) …Form 7

[0101] Furthermore, in the angle θ1 and the width Wx, there exists a relationship as shown in Equation 8.

[0102] θ1=0.0042Wx+169.65…Equation 8

[0103] B: Second Implementation Method

[0104] Figure 9 This is a schematic diagram showing the flow channel structure within the liquid ejector head 24 according to the second embodiment when viewed in the Z-axis direction. Figure 9 As illustrated, a plurality of nozzles N (Na, Nb) are formed on the surface of the liquid ejector head 24 opposite to the medium 11. The plurality of nozzles N are arranged along the Y-axis. Ink is ejected from each of the plurality of nozzles N in the Z-axis direction. That is, the Z-axis corresponds to the direction in which ink is ejected from each nozzle N.

[0105] In the second embodiment, the plurality of nozzles N are divided into a first nozzle array La and a second nozzle array Lb. The first nozzle array La is a collection of nozzles Na arranged in a straight line along the Y-axis. Similarly, the second nozzle array Lb is a collection of nozzles Nb arranged in a straight line along the Y-axis. The first nozzle array La and the second nozzle array Lb are arranged side-by-side in the X-axis direction at predetermined intervals. Furthermore, the positions of each nozzle Na in the Y-axis direction and the positions of each nozzle Nb in the Y-axis direction are different. Figure 9 As illustrated, multiple nozzles N, including nozzle Na and nozzle Nb, are arranged with a spacing (period) θ. The spacing θ is the distance between the centers of nozzle Na and nozzle Nb in the Y-axis direction.

[0106] like Figure 9As illustrated, an independent flow channel array 25 is provided in the liquid nozzle 24. The independent flow channel array 25 is a collection of multiple independent flow channels P (Pa, Pb) corresponding to different nozzles N. Each of the multiple independent flow channels P is a flow channel communicating with the nozzle N corresponding to that independent flow channel P. Each independent flow channel P extends along the X-axis. The independent flow channel array 25 is composed of multiple independent flow channels P arranged side-by-side along the Y-axis. Furthermore, although in Figure 9 For convenience, each independent flow channel P is illustrated as a simple straight line, but the actual shape of each independent flow channel P will be described later.

[0107] Each independent flow channel P includes a pressure chamber C (Ca, Cb). The pressure chamber C within each independent flow channel P is a space for storing ink ejected from the nozzle N connected to that independent flow channel P. That is, by changing the pressure of the ink within the pressure chamber C, the ink is ejected from the nozzle N. Furthermore, the pressure chamber C of the second embodiment is compared with that of the reference... Figures 5 to 8 The pressure chamber C of the first embodiment is constructed in the same manner. Therefore, the liquid ejector head 24 of the second embodiment can reduce the stress at the first end 60a in the same way as the liquid ejector head 24 of the first embodiment. Therefore, the liquid ejector head 24 of the second embodiment has improved durability.

[0108] like Figure 9 As illustrated, a first common liquid chamber R1 and a second common liquid chamber R2 are provided in the liquid nozzle 24. The first common liquid chamber R1 and the second common liquid chamber R2 extend in the Y-axis direction, each spanning the entire area where the plurality of nozzles N are distributed. In a top view taken from the Z1 direction, the independent flow channel row 25 and the plurality of nozzles N are located between the first common liquid chamber R1 and the second common liquid chamber R2.

[0109] Multiple independent flow channels P are connected to a first common liquid chamber R1. Specifically, the end E1 of each independent flow channel P in the X2 direction is connected to the first common liquid chamber R1. Furthermore, the multiple independent flow channels P are also connected to a second common liquid chamber R2. Specifically, the end E2 of each independent flow channel P in the X1 direction is connected to the second common liquid chamber R2. As understood from the above description, each independent flow channel P connects the first common liquid chamber R1 and the second common liquid chamber R2. Ink supplied from the first common liquid chamber R1 to each independent flow channel P is ejected from the nozzle N corresponding to that independent flow channel P. Furthermore, the portion of ink supplied from the first common liquid chamber R1 to each independent flow channel P that is not ejected from the nozzle N is discharged into the second common liquid chamber R2.

[0110] like Figure 9As illustrated, the liquid ejection device 100 of the second embodiment includes a circulation mechanism 26. The circulation mechanism 26 is a mechanism that circulates the ink discharged from each individual flow channel P to the second common liquid chamber R2 back into the first common liquid chamber R1. Specifically, the circulation mechanism 26 includes a first supply pump 261, a second supply pump 262, a storage container 263, a circulation flow channel 264, and a supply flow channel 265.

[0111] The first supply pump 261 is a pump that supplies ink stored in the liquid container 12 to the storage container 263. The storage container 263 is a secondary tank that temporarily stores the ink supplied from the liquid container 12. The circulation channel 264 is a channel that connects the second common liquid chamber R2 and the storage container 263. In the storage container 263, in addition to the ink stored in the liquid container 12 supplied from the first supply pump 261, ink discharged from each independent channel P to the second common liquid chamber R2 is also supplied via the circulation channel 264. The second supply pump 262 is a pump that delivers ink stored in the storage container 263. The ink delivered from the second supply pump 262 is supplied to the first common liquid chamber R1 via the supply channel 265.

[0112] The independent flow channel row 25 includes multiple independent flow channels P, each connected to a nozzle Na in the first nozzle row La. The multiple independent flow channels Pb are each connected to a nozzle Nb in the second nozzle row Lb. The independent flow channels Pa and Pb are arranged alternately along the Y-axis; that is, they are adjacent in the Y-axis direction.

[0113] As understood from the above explanation, the multiple pressure chambers Ca corresponding to the different nozzles Na of the first nozzle array La are arranged in a straight line along the Y-axis. Similarly, the multiple pressure chambers Cb corresponding to the different nozzles Nb of the second nozzle array Lb are arranged in a straight line along the Y-axis. The arrangement of the multiple pressure chambers Ca and the arrangement of the multiple pressure chambers Cb are set side by side in the X-axis direction at predetermined intervals. The positions of the pressure chambers Ca in the Y-axis direction are different from the positions of the pressure chambers Cb in the Y-axis direction.

[0114] The specific structure of the liquid ejector head 24 will be described in detail below. Figure 10 for Figure 9 The sectional view of line aa in the middle. Figure 11 for Figure 9 A cross-sectional view along the bb line. Figure 10 The diagram shows a cross-section through the independent flow channel Pa. Figure 11 The diagram shows a cross-section of Pb through an independent flow channel.

[0115] like Figure 10 as well as Figure 11 As illustrated, the liquid ejector head 24 includes a flow channel structure 30, multiple piezoelectric elements 41, a housing portion 42, a protective substrate 43, and a wiring substrate 44. The flow channel structure 30 is a structure in which a flow channel including a first common liquid chamber R1, a second common liquid chamber R2, multiple independent flow channels P, and multiple nozzles N are formed inside.

[0116] The flow channel structure 30 is a structure formed by stacking a nozzle plate 31, a first flow channel substrate 32, a second flow channel substrate 331, a pressure chamber substrate 34, and a vibrating plate 35 in the Z1 direction in the above order. The various components constituting the flow channel structure 30 are manufactured by processing a single crystal substrate, for example, using semiconductor manufacturing technology.

[0117] In the nozzle plate 31, a plurality of nozzles N are formed. Each of the plurality of nozzles N is a circular through-hole through which ink passes. The nozzle plate 31 of the first embodiment is a plate-shaped member including a surface Fa1 located in the Z2 direction and a surface Fa2 located in the Z1 direction.

[0118] Figure 10 as well as Figure 11 The first flow channel substrate 32 is a plate-shaped member including a surface Fb1 in the Z2 direction and a surface Fb2 in the Z1 direction. The second flow channel substrate 331 is a plate-shaped member including a surface Fc1 in the Z2 direction and a surface Fc2 in the Z1 direction. The second flow channel substrate 331 is thicker than the first flow channel substrate 32.

[0119] The pressure chamber substrate 34 is a plate-shaped member including a surface Fd1 in the Z2 direction and a surface Fd2 in the Z1 direction. The vibrating plate 35 is a plate-shaped member including a surface Fe1 in the Z2 direction and a surface Fe2 in the Z1 direction.

[0120] The components constituting the flow channel structure 30 are formed into elongated rectangular shapes in the Y-axis direction and are joined together with each other using, for example, an adhesive. For example, the surface Fa2 of the nozzle plate 31 is joined to the surface Fb1 of the first flow channel substrate 32, and the surface Fb2 of the first flow channel substrate 32 is joined to the surface Fc1 of the second flow channel substrate 331. Furthermore, the surface Fc2 of the second flow channel substrate 331 is joined to the surface Fd1 of the pressure chamber substrate 34, and the surface Fd2 of the pressure chamber substrate 34 is joined to the surface Fe1 of the vibrating plate 35.

[0121] Spaces O11 and O21 are formed in the first flow channel substrate 32. Spaces O11 and O21 are elongated openings in the Y-axis direction. Spaces O12 and O22 are formed in the second flow channel substrate 331. Spaces O12 and O22 are also elongated openings in the Y-axis direction. Spaces O11 and O12 are interconnected. Similarly, spaces O21 and O22 are interconnected. A vibration absorber 361 that encloses space O11 and a vibration absorber 362 that encloses space O21 are provided on the surface Fb1 of the first flow channel substrate 32. The vibration absorbers 361 and 362 are layered components formed of an elastic material.

[0122] The housing 42 is a shell for storing ink. The housing 42 is bonded to the surface Fc2 of the second flow channel substrate 331. Within the housing 42, a space O13 communicating with space O12 and a space O23 communicating with space O22 are formed. Spaces O13 and O23 are elongated spaces in the Y-axis direction. Spaces O11, O12, and O13 are interconnected to form a first common liquid chamber R1. Similarly, spaces O21, O22, and O23 are interconnected to form a second common liquid chamber R2. A vibration absorber 361 forms the wall of the first common liquid chamber R1 and absorbs pressure fluctuations of the ink within the first common liquid chamber R1. A vibration absorber 362 forms the wall of the second common liquid chamber R2 and absorbs pressure fluctuations of the ink within the second common liquid chamber R2.

[0123] A supply port 421 and a discharge port 422 are formed on the housing portion 42. The supply port 421 is a pipe communicating with the first common liquid chamber R1 and connected to the supply flow channel 265 of the circulation mechanism 26. Ink supplied from the second supply pump 262 to the supply flow channel 265 is supplied to the first common liquid chamber R1 through the supply port 421. On the other hand, the discharge port 422 is a pipe communicating with the second common liquid chamber R2 and connected to the circulation flow channel 264 of the circulation mechanism 26. Ink in the second common liquid chamber R2 is supplied to the circulation flow channel 264 through the discharge port 422.

[0124] Multiple pressure chambers C (Ca, Cb) are formed in the pressure chamber substrate 34. Each pressure chamber C is the gap between the surface Fc2 of the second flow channel substrate 331 and the surface Fe1 of the vibrating plate 35. Each pressure chamber C is formed as an elongated strip along the X-axis when viewed from above in the Z1 direction.

[0125] The vibrating plate 35 is a plate-shaped component capable of elastic vibration. The vibrating plate 35 is constructed, for example, by laminating a first layer of silicon oxide (SiO2) and a second layer of zirconium oxide (ZrO2). Alternatively, a portion in the thickness direction can be selectively removed from the plate-shaped component of a predetermined thickness, corresponding to the pressure chamber C, thereby integrally forming the vibrating plate 35 and the pressure chamber substrate 34. Furthermore, the vibrating plate 35 can also be formed as a single layer.

[0126] On the surface Fe2 of the vibrating plate 35, a plurality of piezoelectric elements 41 corresponding to different pressure chambers C are provided. When viewed from above in the Z1 direction, the piezoelectric element 41 corresponding to each pressure chamber C overlaps with that pressure chamber C. Specifically, each piezoelectric element 41 is constructed by stacking a first electrode and a second electrode that are opposite each other, and a piezoelectric layer formed between the two electrodes. Each piezoelectric element 41 is an energy-generating element that causes the ink in the pressure chamber C to be ejected from the nozzle N by varying the pressure of the ink. That is, the vibrating plate 35 is vibrated by deforming the piezoelectric element 41 using a drive signal, and the pressure chamber C is expanded and contracted by the vibration of the vibrating plate 35, thereby ejecting the ink from the nozzle N. The pressure chambers C (Ca, Cb) are defined as the range within the independent flow channel P where the vibrating plate 35 is vibrated by the deformation of the piezoelectric element 41.

[0127] The protective substrate 43 is a plate-shaped component disposed on the surface Fe2 of the vibrating plate 35, protecting the plurality of piezoelectric elements 41 and reinforcing the mechanical strength of the vibrating plate 35. The plurality of piezoelectric elements 41 are housed between the protective substrate 43 and the vibrating plate 35. Furthermore, a wiring substrate 44 is mounted on the surface Fe2 of the vibrating plate 35. The wiring substrate 44 is a mounting component for electrically connecting the control unit 21 and the liquid ejector head 24. For example, a flexible wiring substrate 44 such as an FPC (Flexible Printed Circuit) or an FFC (Flexible Flat Cable) is preferably used. A drive circuit 45 for supplying drive signals to each piezoelectric element 41 is mounted on the wiring substrate 44.

[0128] C: Other implementation methods

[0129] The liquid nozzle 24 is not limited to the structure illustrated in the first and second embodiments described above. The liquid nozzle 24 may also be a structure composed of two or more structures selected from the structures illustrated in the first and second embodiments, within a non-contradictory range.

[0130] D: Variation Example

[0131] While embodiments of this disclosure have been described above, this disclosure is not limited to the above-described embodiments, and various modifications can be applied. Specific variations that can be applied to the foregoing embodiments are illustrated below. Methods arbitrarily selected from the examples below may also be appropriately combined within a non-contradictory scope.

[0132] (1) Although the structures for circulating ink from the second common liquid chamber R2 to the first common liquid chamber R1 have been illustrated in the aforementioned embodiments, the technical concept of ink circulation can be omitted as needed. Therefore, the second common liquid chamber R2 and the circulation mechanism 26 can also be omitted as needed.

[0133] (2) The energy generating element that causes pressure changes in the ink within the pressure chamber C is not limited to the piezoelectric element 41 exemplified in the aforementioned manner. For example, a heating element that causes pressure changes in the ink by generating bubbles inside the pressure chamber C through heating can also be used as the energy generating element. In the structure that uses a heating element as the energy generating element, the area in the independent flow channel P where bubbles are generated due to heating by the heating element is defined as the pressure chamber C.

[0134] (3) Although the above-described manner exemplifies a serial liquid ejection device 100 that reciprocates the conveyor 231 equipped with the liquid ejection head 24, the present invention is also applied to a row-type liquid ejection device in which multiple nozzles N are distributed across the entire width of the medium 11.

[0135] (4) In the aforementioned manner, there is a case where the width Wz in the Z1 direction of the bent portion 62 is greater than the width Wx in the X1 direction of the bent portion 62. In this case, the first wall surface 3Aa is not inclined relative to the first surface 3A, and the first surface 3A and the first wall surface 3Aa can also be contained in the same plane. If the width Wz is greater than the width Wx, the magnitude of the stress in the first end 60a will be reduced.

[0136] (5) In the aforementioned manner, there is a case where the radius of curvature of the first portion 621 is greater than the radius of curvature of the second portion 622. In this case, the first wall surface 3Aa is not inclined relative to the first surface 3A, and the first surface 3A and the first wall surface 3Aa can also be contained in the same plane. If the radius of curvature of the first portion 621 is greater than the radius of curvature of the second portion 622, the magnitude of the stress in the first end 60a will be reduced.

[0137] E: Supplement

[0138] The structure of the liquid ejection device 100 is not limited to Figures 1 to 11The structure shown, for example, could also be a common liquid ejection device that circulates ink, other than the structure illustrated in these figures. Furthermore, the liquid ejection device 100 illustrated in the foregoing embodiments can be used in various devices such as fax machines or copiers, in addition to equipment specifically designed for printing; the application of the present invention is not particularly limited. Of course, the application of the liquid ejection device is not limited to printing. For example, a liquid ejection device that ejects a solution of color material can be used as a manufacturing apparatus for color filters in display devices such as liquid crystal display panels. Furthermore, a liquid ejection device that ejects a solution of conductive material can be used as a manufacturing apparatus for wiring or electrodes in wiring substrates. Moreover, a liquid ejection device that ejects a solution of organic matter related to living organisms can, for example, be used as a manufacturing apparatus for biochips.

[0139] Furthermore, the effects described in this specification are ultimately illustrative or exemplary, and not limiting. In other words, those skilled in the art will recognize that the invention, based on the description herein, can achieve other obvious effects while performing or replacing the aforementioned effects.

[0140] Although preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to the examples described. It is obvious to those skilled in the art that various modifications or alterations will arise within the scope of the technical concept set forth in the claims, and these modifications are also understood to fall within the technical scope of the present invention.

[0141] F: Postscript

[0142] From the examples above, the following structure can be understood, for instance.

[0143] Furthermore, in this application, "overlapping" of elements A and B when viewed from a specific direction means that, when viewed along that direction, at least a portion of element A and at least a portion of element B overlap. It is not necessary for all of element A and all of element B to overlap; as long as at least a portion of element A overlaps with at least a portion of element B, it can be interpreted as "element A and element B overlap".

[0144] As one embodiment of this disclosure, the liquid ejector head includes: an energy generating element that generates energy to apply pressure to a liquid in a pressure chamber; a vibrating plate that vibrates by the energy; a pressure chamber substrate having a first surface in contact with a portion of the bottom surface of the vibrating plate and a first wall surface connected to the first surface; a recess is provided on the bottom surface of the vibrating plate, the recess having a bottom and a curved portion surrounding the bottom, the curved portion being provided across the end of the bottom and the end of the recess and forming a curved shape; a plurality of wall surfaces constituting the inner wall of the pressure chamber including the surface of the recess and the first wall surface, the angle formed by the first surface and the first wall surface being greater than 90 degrees and less than 180 degrees. According to this embodiment, the durability of the liquid ejector head is improved because the stress at the boundary between the first surface and the first wall surface can be reduced.

[0145] According to Method 2, a specific example of Method 1, the angle formed by the first surface and the first wall surface is greater than 150 degrees and less than 180 degrees. This method can improve the durability of the liquid nozzle while reducing structural crosstalk.

[0146] According to embodiment 3, which is a specific example of embodiment 1 or embodiment 2, the vibrating plate extends in a first direction, and the width of the curved portion in the first direction is smaller than the width of the curved portion in a second direction that is perpendicular to the vibrating plate.

[0147] According to embodiment 4, which is a specific example of any of embodiments 1 to 3, the bent portion includes a first portion and a second portion. The first portion includes the boundary between the pressure chamber substrate and the bent portion, and the second portion includes the bottom and the boundary of the bent portion. The radius of curvature of the first portion is larger than the radius of curvature of the second portion. According to this embodiment, the width of the bent portion in the second direction can be reduced while decreasing the magnitude of stress at the boundary between the first surface and the first wall surface. Therefore, the durability of the liquid ejector head can be improved, and problems arising during the manufacturing process of the vibrating plate can be suppressed.

[0148] According to Method 5, which is a specific example of any of Methods 1 to 4, the radius of curvature of the surface is less than 150 nm.

[0149] According to embodiment 6, which is a specific example of any one of embodiments 1 to 5, the pressure chamber substrate has a second wall connected to the first wall, and the second wall is included among the plurality of walls constituting the inner wall of the pressure chamber. The angle formed by the first wall and the second wall is substantially equal to the angle obtained by subtracting the angle formed by the first wall and the first wall from 270 degrees.

[0150] According to embodiment 7, which is a specific example of embodiment 6, the vibrating plate extends in a first direction, and when the recess is viewed in a second direction perpendicular to the vibrating plate, the position of the bottom and the boundary of the curved portion in the first direction is substantially consistent with the position of the second wall surface in the first direction.

[0151] According to embodiment 8, which is a specific example of any one of embodiments 1 to 7, the vibrating plate extends in a first direction, the pressure chamber substrate has a second surface and a third wall surface, the second surface is in contact with a portion of the bottom surface of the vibrating plate, the third wall surface is connected to the second surface, the position of the second surface in the second direction is substantially the same as the position of the first surface in the second direction, the third wall surface faces the first wall surface in the first direction, and the angle formed by the second surface and the third wall surface is substantially equal to the angle formed by the first surface and the first wall surface.

[0152] According to embodiment 9, a specific example of embodiment 8, the pressure chamber substrate includes a second wall and a fourth wall. The second wall is connected to the first wall, and the fourth wall is connected to the third wall. The fourth wall is included among the plurality of walls constituting the inner wall of the pressure chamber. The angle formed by the third and fourth walls is substantially equal to the angle formed by the first and second walls. According to this embodiment, since the angle between the second and third walls is equal to the angle between the first and second walls, the stress acting at the boundary between the second and third walls is substantially equal to the stress acting at the boundary between the first and second walls. Therefore, the durability of the liquid ejector head is improved.

[0153] According to embodiment 10, which is a specific example of any one of embodiments 1 to 9, the pressure chamber substrate is formed of silicon, and at least a portion of the vibrating plate is formed of silicon oxide.

[0154] As one aspect of this disclosure, the liquid ejection device according to aspect 11 includes: any one of aspect 1 to aspect 10; and a control unit that controls the ejection action of the liquid ejection from the liquid ejection head.

[0155] Symbol Explanation

[0156] Pressure chamber…C, Ca, Cb, Ca1, Ca2, Cb1, Cb2; Nfa, Nfb…nozzle flow channel; 35…vibrating plate; 41…piezoelectric element; 60…recess; 60a…first end; 61…bottom; 61a…second end; 62…bend; 100…liquid ejection device; 621…first part; 622…second part; first surface…3A; second surface…3B; first wall surface…3Aa; second wall surface…3Ab; third wall surface…3Ba; fourth wall surface…3Bb.

Claims

1. A liquid ejection head, characterized by, Possessing: an energy generating element that generates energy for applying pressure to a liquid in a pressure chamber; a vibrating plate that vibrates by the energy; a pressure chamber substrate that has a first surface that interfaces with a portion of a bottom surface of the vibrating plate, and a first wall surface that is continuous with the first surface, the first wall surface is inclined with respect to the first surface, and extends away from the vibrating plate toward the pressure chamber, a recess is provided on the bottom surface of the vibrating plate, the recess has a bottom portion and a curved portion that surrounds the bottom portion, the curved portion is provided between an end portion that straddles the bottom portion and an end portion of the recess, and forms a curved surface shape, a plurality of wall surfaces that constitute inner walls of the pressure chamber include a surface of the recess and the first wall surface, an angle formed by the first surface and the first wall surface is greater than 90 degrees and less than 180 degrees.

2. The liquid ejection head according to claim 1, wherein an angle formed by the first surface and the first wall surface is greater than 150 degrees and less than 180 degrees.

3. The liquid ejection head according to claim 1 or 2, wherein the vibrating plate extends in a first direction, a width of the curved portion in the first direction is smaller than a width of the curved portion in a second direction that is perpendicular with respect to the vibrating plate.

4. The liquid ejection head according to claim 1, wherein the curved portion includes a first portion that includes a boundary of the pressure chamber substrate and the curved portion, and a second portion that includes a boundary of the bottom portion and the curved portion, a radius of curvature of the first portion is greater than a radius of curvature of the second portion.

5. The liquid ejection head according to claim 1, wherein a radius of curvature of the curved surface is 150 nm or less.

6. The liquid ejection head according to claim 1, wherein the pressure chamber substrate possesses a second wall surface that is continuous with the first wall surface, a plurality of wall surfaces that constitute inner walls of the pressure chamber include the second wall surface, an angle formed by the first wall surface and the second wall surface is substantially equal to an angle obtained by subtracting an angle formed by the first surface and the first wall surface from 270 degrees.

7. The liquid ejection head according to claim 6, wherein the vibrating plate extends in a first direction, a position of a boundary of the bottom portion and the curved portion in the first direction substantially coincides with a position of the second wall surface in the first direction when the recess is observed in a second direction that is perpendicular with respect to the vibrating plate.

8. The liquid ejection head according to claim 1, wherein the vibrating plate extends in a first direction, the pressure chamber substrate possesses a second surface that interfaces with a portion of a bottom surface of the vibrating plate, and a third wall surface that is continuous with the second surface, a position of the second surface in a second direction that is perpendicular with respect to the vibrating plate substantially coincides with a position of the first surface in the second direction, the third wall surface faces the first wall surface in the first direction, An angle formed by the second face and the third wall face is substantially equal to an angle formed by the first face and the first wall face.

9. The liquid ejection head according to claim 8, wherein The pressure chamber substrate has a second wall face connected to the first wall face and a fourth wall face connected to the third wall face, The plurality of wall faces constituting the inner wall of the pressure chamber include the fourth wall face, An angle formed by the third wall face and the fourth wall face is substantially equal to an angle formed by the first wall face and the second wall face.

10. The liquid ejection head according to claim 1, wherein The pressure chamber substrate is formed of silicon, At least a portion of the vibrating plate is formed of silicon oxide.

11. A liquid discharge apparatus characterized by comprising: has; the liquid ejection head according to any one of claims 1 to 10; a control section that controls an ejection operation from the liquid ejection head.

Images