Liquid discharge head

Abstract

To provide a liquid discharge head in which strength of a passage part can be improved.SOLUTION: A liquid discharge head according to an embodiment comprises a nozzle plate and a passage part. The nozzle plate has a plurality of nozzles that discharges droplets. The passage part comprises a plurality of passage substrates having openings or grooves and is laminated and arranged, which constitutes a passage formed of the opening parts or of the grooves. The opening or the groove which is longest in one direction of the plurality of openings or the plurality of grooves is configured to be smaller in dimension of a width crossing the one direction and a direction of the laminate than the other opening or the other groove.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In a liquid ejection head such as an inkjet head, a method is used in which a vibration plate is deformed using an actuator made of a piezoelectric material such as PZT (lead zirconate titanate) to deform a pressure chamber facing the vibration plate, thereby ejecting ink from a nozzle communicating with the pressure chamber. The liquid ejection head includes a plurality of actuators bonded to the vibration plate, and a flow path portion that forms a plurality of pressure chambers facing the vibration plate and flow paths communicating with the pressure chambers. In some of the flow path portions of such inkjet heads, the flow path portion is formed by stacking a plurality of flow path plates having slits of a predetermined shape. Depending on the shape of the flow path, the slits become elongated, making it difficult to ensure the shape of the flow path. In particular, in a circulation method in which ink circulates in a pressure chamber, the slits become even more elongated. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-149368 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a liquid ejection head capable of improving the strength of a flow path portion. [Means for solving the problem]

[0005] A liquid ejection head according to one embodiment includes a nozzle plate and a flow path section. The nozzle plate has a plurality of nozzles that eject liquid droplets. The flow path section includes a plurality of flow path substrates that have openings or grooves and are arranged in a stacked manner, and constitutes a flow path formed by the openings or grooves. Of the plurality of openings or grooves, the opening or groove that is longest in one direction is configured to have a width dimension intersecting the one direction and the stacking direction that is smaller than the other openings or grooves. [Brief description of the drawings]

[0006] [Figure 1] FIG. 2 is a cross-sectional view showing the configuration of a portion of the inkjet head according to the first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing a configuration of a portion of the inkjet head. [Diagram 3] FIG. 2 is a plan view showing the configuration of a flow path portion of the inkjet head. [Figure 4] FIG. 2 is a cross-sectional view of a first flow path substrate of the inkjet head. [Diagram 5] FIG. 4 is a cross-sectional view of a second flow path substrate of the inkjet head. [Figure 6] FIG. 1 is an explanatory diagram showing a schematic configuration of an inkjet recording apparatus according to a first embodiment. [Figure 7] FIG. 11 is a cross-sectional view showing a configuration of a portion of an inkjet head according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] An inkjet head 1, which is a liquid ejection head according to the first embodiment, and an inkjet recording device 100, which is a liquid ejection device, will be described below with reference to Figs. 1 to 6. Fig. 1 is a cross-sectional view showing a part of the configuration of the inkjet head according to the first embodiment, and Fig. 2 is a cross-sectional view showing a part of the configuration of the inkjet head. Fig. 3 is a plan view showing the configuration of a flow path part of the inkjet head, Fig. 4 is a cross-sectional view showing the configuration of a first flow path substrate, and Fig. 5 is a cross-sectional view of a second flow path substrate. Fig. 6 is an explanatory diagram showing a schematic configuration of an inkjet recording device. In the figure, arrows X, Y, and Z respectively indicate three directions perpendicular to each other. In this embodiment, X is the parallel direction of the nozzles 51 and the pressure chambers 31, Y is the extension direction, and Z is along the axial direction of the nozzles. In each figure, the configuration is enlarged, reduced, or omitted as appropriate for the purpose of explanation.

[0008] 1 and 2, the inkjet head 1 includes an actuator section 20, a vibration plate 30, a manifold 40 as a flow path section having a plurality of flow path substrates 401, 402, a nozzle plate 50 as a nozzle section having a plurality of nozzles 51, a frame section 45 as a structural section, and a drive circuit 70. As an example, the inkjet head 1 in this embodiment shows an example in which the stacking direction of the piezoelectric layer 211, the vibration direction of the piezoelectric element 21, and the vibration direction of the vibration plate 30 are all along the Z direction. In this embodiment, on the back side of the nozzle plate 50, the vibration plate 30 and the manifold 40 form a flow path structure section that forms an ink flow path 35 in the head 1. The inkjet head 1 is of a circulation type that circulates liquid in a predetermined flow path.

[0009] The actuator section 20 is made of, for example, a piezoelectric member and includes a plurality of driving piezoelectric elements 21 and a plurality of non-driving piezoelectric elements 22 as actuators alternately arranged along the column direction, and a piezoelectric structure section 26 that integrally connects the plurality of piezoelectric elements 21, 22. In this embodiment, a nozzle 51 is provided at the center of the actuator section 20 in the extension direction, and the actuator section 20 has a structure in which one side and the other side are symmetrical with respect to the nozzle 51. For example, the actuator section 20 is joined to a rectangular base.

[0010] In the actuator section 20, the driving piezoelectric elements 21 and the non-driven piezoelectric elements 22 are arranged in parallel at regular intervals. As an example, the driving piezoelectric elements 21 and the non-driven piezoelectric elements 22 are all configured in the shape of a rectangular parallelepiped column having the same external shape. The actuator section 20 is divided into a plurality of sections by a plurality of grooves 23, and the driving piezoelectric elements 21 and the non-driven piezoelectric elements 22 are arranged in a row at the same pitch by grooves 23 of the same width, for example.

[0011] For example, the multiple driving piezoelectric elements 21 and the multiple non-driven piezoelectric elements 22 are each configured in a rectangular shape when viewed in a planar view from the Z direction, which is the axial direction of the nozzle 51, with the short side direction aligned with the row direction of the element row and the long side direction aligned with an extension direction perpendicular to the row direction and the Z direction.

[0012] The driving piezoelectric elements 21 are arranged in positions in the Z direction facing the multiple pressure chambers 31 formed in the manifold 40. As an example, the center positions in the row direction and extension direction of the driving piezoelectric elements 21 and the center positions in the row direction and extension direction of the pressure chambers 31 are arranged side by side in the Z direction.

[0013] The non-driven piezoelectric elements 22 are arranged in positions in the Z direction facing the partition walls 42 formed in the manifold 40. As an example, the center positions in the row direction and extension direction of the non-driven piezoelectric elements 22 and the center positions in the row direction and extension direction of the partition walls 42 are arranged side by side in the Z direction.

[0014] For example, the laminated piezoelectric member constituting the actuator section 20 is formed by stacking and sintering sheet-like piezoelectric materials. The actuator section 20 is formed by dicing the laminated piezoelectric member from one end face to form grooves 23, thereby forming a plurality of rectangular columnar piezoelectric elements at predetermined intervals. Electrodes and the like are then provided on the formed columnar elements to form a plurality of driving piezoelectric elements 21 and a plurality of non-driving piezoelectric elements 22 that are alternately arranged. The driving piezoelectric elements 21 and the non-driving piezoelectric elements 22 are alternately arranged in parallel in the column direction, sandwiching the grooves 23 therebetween.

[0015] The piezoelectric members constituting the driving piezoelectric element 21 and the non-driven piezoelectric element 22 are, for example, laminated piezoelectric elements. The driving piezoelectric element 21 and the non-driven piezoelectric element 22 each include a plurality of laminated piezoelectric layers 211 and internal electrodes 221, 222 formed on the main surface of each piezoelectric layer 211. As an example, the driving piezoelectric element 21 and the non-driven piezoelectric element 22 have the same laminated structure. The driving piezoelectric element 21 and the non-driven piezoelectric element 22 each include external electrodes 223, 224 formed on the surface.

[0016] The piezoelectric layers 211 are made of a piezoelectric material such as PZT (lead zirconate titanate) or lead-free KNN (potassium sodium niobate). The thickness direction of the piezoelectric layers 211 is stacked along the stacking direction. For example, in this embodiment, the thickness direction and stacking direction of the piezoelectric layers 211 are arranged along the vibration direction (Z direction).

[0017] The internal electrodes 221 and 222 are conductive films formed into a predetermined shape using 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 but does not reach the other end of the piezoelectric layer 211 in the extension direction (Y direction) that is perpendicular to both the row direction (X direction) in which the multiple driving piezoelectric elements 21 and the multiple non-driving piezoelectric elements 22 are arranged and the vibration direction (Z direction). The other internal electrode 222 is formed in a region that does not reach one end of the piezoelectric layer 211 but reaches the other end of the piezoelectric layer 211 in the extension direction. The internal electrodes 221 and 222 are connected to external electrodes 223 and 224 formed on the side surfaces of the piezoelectric elements 21 and 22, respectively.

[0018] Furthermore, the laminated piezoelectric members constituting the driving piezoelectric element 21 and the non-driving piezoelectric element 22 may further include a dummy layer on either or both of the ends on the nozzle plate 50 side or the opposite side. For example, the dummy layer is made of the same material as the piezoelectric layer 211, has an electrode on only one side, and is not deformed because no electric field is applied. For example, the dummy layer does not function as a piezoelectric body, but serves to fix the actuator unit 20 to the base, or serves as a polishing allowance for polishing to achieve precision during or after assembly.

[0019] The external electrodes 223, 224 are formed on the surfaces of the driving piezoelectric elements 21 and the non-driven piezoelectric elements 22, and are formed by collecting the ends of the internal electrodes 221, 222. For example, the external electrodes 223, 224 are formed on one end face and the other end face in the extension direction of the piezoelectric layer 211, respectively. The external electrodes 223, 224 are formed by a known method such as plating or sputtering, using Ni, Cr, Au, or the like. The external electrodes 223 and 224 have different polarities. The external electrodes 223 and 224 are disposed on different side surfaces of the driving piezoelectric elements 21 and the non-driven piezoelectric elements 22, respectively. The external electrodes 223 and 224 may be disposed on different regions of the same side surfaces of the driving piezoelectric elements 21 and the non-driven piezoelectric elements 22.

[0020] In this embodiment, as an example, the external electrode 223 is an individual electrode, and the external electrode 224 is a common electrode. The external electrode 223, which serves as an individual electrode for the multiple driving piezoelectric elements 21 and the multiple non-driving piezoelectric elements 22, has an electrode layer divided by grooves 23 and is arranged independently of each other. The external electrode 224, which serves as a common electrode, has an electrode layer connected to each other, for example, on the side surface of the piezoelectric structure 26, and is, for example, grounded. The external electrodes 223 and 224 are connected to the drive circuit 70, for example, via a wiring film. For example, each of the external electrodes 223 and 224 is connected to the control unit 150 via a drive IC 72 of the drive circuit 70, and is configured to be drive-controllable. The arrangement of the common electrode and the individual electrodes may be reversed.

[0021] The vibration direction of each of the piezoelectric elements 21, 22 is along the stacking direction, and is displaced in the d33 direction by application of an electric field. Each of the piezoelectric elements 21, 22 has three or more stacked layers of piezoelectric layers 211 and internal electrodes 221, 222. As an example, each of the piezoelectric elements 21, 22 has three or more and 50 or less layers, each layer has a thickness of 10 μm or more and 40 μm or less, and the product of the thickness and the total number of stacked layers is less than 1000 μm.

[0022] In the inkjet head 1, the driving piezoelectric element 21 vibrates when a voltage is applied to the internal electrodes 221, 222 via the external electrodes 223, 224. In this embodiment, the driving piezoelectric element 21 vibrates longitudinally along the stacking direction of the piezoelectric layer 211. The longitudinal vibration here means, for example, "vibration in the thickness direction defined by the piezoelectric constant d33." The driving piezoelectric element 21 displaces the vibration plate 30 and deforms the pressure chamber 31 by the longitudinal vibration.

[0023] The vibration plate 30 extends along a plane perpendicular to the Z direction, which is the vibration direction, and is bonded to one side of the vibration direction of the piezoelectric layer 211 of the plurality of piezoelectric elements 21, 22, i.e., the surface on the nozzle plate 50 side. The vibration plate 30 faces the plurality of nozzles 51 through the pressure chambers 31 in the Z direction, which is the vibration direction. The vibration plate 30 is configured to be deformable, for example. The vibration plate 30 is bonded to the driving piezoelectric element 21 and the non-driving piezoelectric element 22 of the actuator section 20 and to the frame section 45. For example, the vibration plate 30 has a vibration region 301 facing the piezoelectric elements 21, 22 and a support region 302 facing the frame section 45. The vibration plate 30 is provided between the flow path substrate 401 and the actuator section 20 in the vibration direction. The vibration plate 30 is arranged overlapping the plurality of flow path substrates 401, 402, and 403, and forms a part of the ink flow path 35.

[0024] The vibration region 301 is, for example, in the form of a flat plate arranged such that the thickness direction coincides with the vibration direction of the piezoelectric layer 211. The vibration plate 30 has a surface direction extending in the arrangement direction of the multiple driving piezoelectric elements 21 and the multiple non-driving piezoelectric elements 22. The vibration plate 30 is, for example, a metal plate. The vibration plate 30 has multiple vibration parts that face each pressure chamber 31 and are individually displaceable. The vibration plate 30 is formed by integrally connecting the multiple vibration parts.

[0025] As an example, the vibration plate 30 is made of a nickel or SUS plate, and the thickness dimension along the vibration direction is set to about 5 μm to 15 μm. The vibration region 301 may have folds or steps formed in the regions adjacent to the vibration regions or between adjacent vibration regions so that the multiple vibration regions can be easily displaced. The vibration region 301 is deformed by the displacement of the region arranged opposite the driving piezoelectric element 21 due to the expansion and compression of the driving piezoelectric element 21. For example, the vibration plate 30 is required to be very thin and have a complex shape, and is formed by electroforming or the like. The vibration plate 30 is joined to the upper end surface of the actuator section 20 by adhesive or the like.

[0026] The support region 302 is a plate-like member disposed between the frame portion 45 and the flow path substrate 401. The vibration plate 30 has a structure in which one side and the other side in the Y direction are symmetrical with respect to the nozzle 51 at the center.

[0027] The manifold 40 is bonded to one side of the diaphragm 30 .

[0028] As shown in FIGS. 1 to 3, the manifold 40 includes a plurality of stacked flow path substrates 401, 402, and 403. As an example, the manifold 40 includes a stack of a flow path substrate 401 and a flow path substrate 402 as a first flow path substrate configured to have the same shape, and a flow path substrate 403 as a second flow path substrate. For example, the plurality of flow path substrates 401, 402, and 403 having openings or grooves according to the viscosity of the ink and the volume to be discharged are combined and joined with the nozzle plate 50 and the vibration plate 30 to form a desired ink flow path 35. The plurality of flow path substrates 401, 402, and 403 are stacked in the stacking direction, and a predetermined ink flow path 35 including an individual liquid chamber 33 communicating with a plurality of nozzles 51, a throttle flow path 34 as an individual flow path, and a pressure chamber 31 is formed by the openings or grooves formed in each of the flow path substrates 401, 402, and 403. As an example, flow path substrates 401, 402, and 403 are stacked in this order from the vibration plate 30 side, and the flow path substrate 403 is disposed opposite the nozzle plate 50.

[0029] The manifold 40 is disposed between the nozzle plate 50 and the vibration plate 30. The manifold 40 is formed by stacking a plurality of flow path substrates 401, 402, 403 and bonding them together to form a predetermined ink flow path 35 (liquid chamber) having a plurality of pressure chambers 31, an individual liquid chamber 33 communicating with the common chamber 32, and a plurality of throttle flow paths 34 (throttle portion) from the individual liquid chamber 33 to the pressure chamber 31. In other words, the manifold 40 forms a peripheral wall portion 41 surrounding the ink flow path 35 (liquid chamber) consisting of the plurality of pressure chambers 31, the plurality of throttle flow paths 34, and the individual liquid chambers 33, a plurality of partition wall portions 42 separating the rows of the plurality of pressure chambers 31, and a side wall portion 43 separating the plurality of throttle flow paths 34 by the plurality of stacked flow path substrates 401, 402, 403. For example, in this embodiment, the manifold 40 forms an example of three rows of ink flow paths 35.

[0030] A flow path substrate 401, which is a first flow path substrate shown in FIGS. 1 to 4, is bonded to the vibration plate 30. The flow path substrate 401 is a plate-like member having the same shape as the vibration plate 30, and is made of a metal material including SUS430, or a resin material such as silicon, for example. The flow path substrate 401 has a first opening 4011 forming a part of the pressure chamber 31 and a second opening 4012 forming a part of the individual liquid chamber 33. For example, the first opening 4011 is arranged in the center of the extension direction in which the ink flow path 35 extends, and the second openings 4012 are arranged on both ends. In the arrangement direction, the openings 4011 and 4012 are arranged in three rows, and a beam-like portion 461 is formed between the openings 4011 adjacent to each other in the arrangement direction, and a beam-like portion 462 is formed between the openings 4012 adjacent to each other in the arrangement direction. The beam-like portions 461 and 462 have the same lengths as the lengths LA and LB of the openings 4011 and 4012, respectively.

[0031] The flow path substrate 402, which is a first flow path substrate, is joined to the flow path substrate 401. The flow path substrate 402 is a plate-like member having the same shape as the flow path substrate 401, and is made of a metal material including SUS430, or a resin material such as silicon, for example. The flow path substrate 402 has a first opening 4021 forming a part of the pressure chamber 31 and a second opening 4022 forming a part of the individual liquid chamber 33. For example, the first opening 4021 is arranged in the center of the extension direction in which the ink flow path 35 extends, and the second openings 4022 are arranged at both ends. In the arrangement direction, the openings 4021, 4022 are arranged in three rows, and a beam-like portion 461 is formed between the openings 4021 adjacent to each other in the arrangement direction, and a beam-like portion 462 is formed between the openings 4012 adjacent to each other in the arrangement direction. The beam-like portions 461, 462 have the same length as the lengths LA, LB of the openings 4021, 4022, respectively, in the longitudinal direction.

[0032] As shown in FIG. 1 to FIG. 3 and FIG. 5, the flow path substrate 403, which is the second flow path substrate, is laminated on the flow path substrate 402 and joined to the flow path substrate 402. The flow path substrate 403 is a plate-like member having the same shape as the vibration plate 30, and is made of a metal material including SUS430, or a resin material such as silicon. The flow path substrate 403 has a long and thin slit 4031 (groove) which constitutes the throttle flow path 34, which is an individual flow path. That is, the slit 4031, which is the longest opening in one direction among the multiple openings or grooves, is configured to have a width dimension smaller than the other openings 4011, 4012, 4021, and 4022. The slit 4031 forms an opening penetrating in the thickness direction, and is formed, for example, to reach both ends in the extension direction in which the ink flow path 35 extends.

[0033] The slits 4031 are rectangular openings, and are arranged in a plurality of rows, for example, in three rows, in the arrangement direction. In the flow channel substrate 403, beam-like portions 463 are formed between the slits 4031 adjacent to each other in the arrangement direction. The beam-like portions 463 have the same length as the length LC of the slits 4031.

[0034] That is, flow path substrate 403 has slits 4031 whose opening length in the extension direction is longer than the other flow path substrates, that is, flow path substrate 401 and flow path substrate 402. For example, slits 4031 of flow path substrate 403 are slits that span the entire length in one direction of ink flow path 35 in the flow path structure portion, and extend from one end to the other end of ink flow path 35 in the extension direction (Y direction).

[0035] For example, the second flow path substrate 403 is configured to have a thickness of 20 μm to 100 μm. For example, in the case of 300 dpi, the pitch of the arrangement of the pressure chambers 31 in the parallel direction is 169 μm, the width Wa of the pressure chambers 31 is about 100 μm to 150 μm, the width Wc of the slit 4031 is smaller than the width Wa of the first opening and the second opening, and therefore the width Wd of the beam-like portion 463 is configured to be larger than the width Wb of the beam-like portions 461 and 462. The width Wa of the pressure chambers 31, the width Wb of the beam-like portions 461 and 462, the width Wc of the slit 4031, and the width Wd of the beam-like portion 463 are width dimensions that intersect with one direction and the stacking direction. In Figs. 4 and 5, the width Wa of the pressure chambers 31, the width Wb of the beam-like portions 461 and 462, the width Wc of the slit 4031, and the width Wd of the beam-like portion 463 are width dimensions in the X direction.

[0036] For example, in this embodiment, some of the slits 4031 are arranged to overlap the openings 4011, 4012, 4021, and 4022 of the other flow channel substrates 401 and 402, and communicate with these openings 4011, 4012, 4021, and 4022.

[0037] In the manifold 40, a plurality of pressure chambers 31 are formed by first openings 4011, 4021 and slits 4031 of a plurality of flow path substrates 401, 402, 403 that are aligned in the stacking direction and communicate with each other. The plurality of pressure chambers 31 are spaces formed on one side of the vibration region 301 of the vibration plate 30, and each pressure chamber 31 communicates with a nozzle 51 formed in the nozzle plate 50. In addition, the pressure chamber 31 is closed on the side opposite to the nozzle plate 50 by the vibration plate 30.

[0038] The multiple pressure chambers 31 communicate with the common chamber 32 via the throttle flow path 34 and the individual liquid chambers 33 and the opening 303. The pressure chambers 31 hold liquid supplied from the common chamber 32, and are deformed by vibration of the vibration plate 30 that forms a part of the pressure chambers 31, thereby ejecting the liquid from the nozzles 51.

[0039] In the manifold 40, the second openings 4012, 4022 and slits 4031 of the multiple flow path substrates 401, 402, 403 that are aligned in the stacking direction and communicate with each other form individual liquid chambers 33 on both sides of the pressure chamber in the Y direction.

[0040] The individual liquid chambers 33 are flow paths that communicate with the ends in the flow direction of the multiple throttle flow paths 34. The individual liquid chambers 33 are formed, for example, between the vibration plate 30 and the nozzle plate 50, and communicate with the common chamber 32 of the frame portion 45. Here, each of the flow path substrates 401, 402, 403 has a structure that is symmetrical on one side and the other side in the Y direction with the nozzle 51 at the center, and the flow path lengths and flow path cross-sectional shapes perpendicular to the Y direction of the individual liquid chambers 33 arranged on both sides in the Y direction with the central pressure chamber 31 at the center are configured to be equal.

[0041] In the manifold 40, throttle channels 34 are formed by slits 4031 in the channel substrate 403. The throttle channels 34 communicate with each pressure chamber 31 and the individual liquid chambers 33, and extend in the Y direction, which is the flow direction. The throttle channels 34 on both sides are configured to have a smaller dimension in the width direction perpendicular to the extension direction, which is the flow direction, than the individual liquid chambers 33 and the pressure chambers 31, and are configured to have a narrow channel cross section.

[0042] Here, each flow path substrate 401, 402, 403 has a structure that is symmetrical on one side and the other side in the Y direction with the nozzle 51 at the center, and the flow path lengths and flow path cross-sectional shapes perpendicular to the Y direction of the throttle flow paths 34 arranged on both sides in the Y direction with the central pressure chamber 31 at the center are configured to be equal. In the manifold 40 , the beam-like portions 461 of the stacked flow path substrates 401 , 402 and the central portion of the beam-like portion 463 of the flow path substrate 403 form partition portions 42 that separate the pressure chambers 31 .

[0043] The partition portion 42 is a wall-shaped member that separates the multiple pressure chambers 31 in the arrangement direction. The partition portion 42 is disposed opposite the non-driven piezoelectric element 22 via the vibration plate 30, and is supported by the non-driven piezoelectric element 22. A plurality of partition portions 42 are provided at the same pitch as the arrangement of the multiple pressure chambers 31.

[0044] In the manifold 40, the sidewall portion 43 that separates the multiple throttle channels 34 is formed by the beam-like portion 463 of the channel substrate 403.

[0045] The side wall portion 43 is a wall-like member that separates the multiple throttle channels 34 in the arrangement direction. For example, the side wall portion 43 is provided so as to communicate with both sides of the pressure chamber 31. The side wall portion 43 serves as a flow path resistance portion configured so that the flow path resistance of the throttle channel 34 is greater than that inside the pressure chamber 31 and the flow path cross-sectional area of ​​the throttle channel 34 is smaller than that inside the pressure chamber 31. A plurality of side wall portions 43 are provided at the same pitch as the pitch at which the multiple pressure chambers 31 are arranged.

[0046] The nozzle plate 50 is configured as a rectangular plate with a thickness of approximately 10 μm to 100 μm, made of a metal such as SUS.Ni or a resin material such as polyimide. The nozzle plate 50 is disposed on one side of the manifold 40 so as to cover the openings on one side of the pressure chambers 31. The nozzle plate 50 has a plurality of nozzles 51 that eject droplets. The plurality of nozzles 51 are holes that penetrate the nozzle plate 50 in the thickness direction. The nozzles 51 are aligned in a first direction, which is the same as the alignment direction of the pressure chambers 31, to form a nozzle row. Each nozzle 51 is provided at a position corresponding to each of the plurality of pressure chambers 31.

[0047] The frame portion 45 is a structure that is joined to the vibration plate 30 together with the piezoelectric elements 21 and 22. The frame portion 45 is provided on the side of the vibration plate 30 opposite the manifold 40, between the piezoelectric elements 21 and 22, and is disposed adjacent to the actuator portion 20 in this embodiment, for example. The frame portion 45 forms the outer shell of the inkjet head 1. The frame portion 45 may also form a liquid flow path therein. In this embodiment, the frame portion 45 is joined to the other side of the vibration plate 30, and forms a common chamber 32 between the frame portion 45 and the vibration plate 30.

[0048] The common chamber 32 is formed inside the frame portion 45, and communicates with the pressure chamber 31 through an opening 303 provided in the vibration plate 30, the individual liquid chamber 33, and the throttle flow path .

[0049] The driving circuit 70 includes a wiring film having one end connected to the external electrodes 223 and 224, a driver IC mounted on the wiring film, and a printed wiring board mounted on the other end of the wiring film.

[0050] The drive circuit 70 applies a drive voltage to the external electrodes 223 and 224 via a driver IC, thereby driving the piezoelectric element 21 and increasing or decreasing the volume of the pressure chamber 31 , thereby causing droplets to be ejected from the nozzle 51 .

[0051] The wiring film is connected to the multiple external electrodes 223, 224. For example, the wiring film is an ACF (anisotropic conductive film) that is fixed by thermocompression or the like to the connection portions of the external electrodes 223, 224. The wiring film is, for example, a COF (chip on film) on which a driver IC is mounted.

[0052] The driver IC is connected to the external electrodes 223, 224 via a wiring film. The driver IC may be connected to the external electrodes 223, 224 by other means such as ACP (anisotropic conductive paste), NCF (non-conductive film), and NCP (non-conductive paste) instead of the wiring film.

[0053] The driver IC generates a control signal and a drive signal for operating each piezoelectric element 21. The driver IC generates a control signal for controlling the timing of ink ejection and the selection of the piezoelectric element 21 to eject ink according to an image signal input from the control unit 150 of the inkjet recording device 100. The driver IC also generates a voltage to be applied to the piezoelectric element 21, that is, a drive signal (electrical signal), according to the control signal. When the driver IC applies a drive signal to the piezoelectric element 21, the piezoelectric element 21 is driven to displace the vibration plate 30 to change the volume of the pressure chamber 31. This causes the ink filled in the pressure chamber 31 to generate pressure vibration. The pressure vibration causes the ink to be ejected from the nozzle 51 provided in the pressure chamber 31. The inkjet head 1 may be configured to realize gradation expression by changing the amount of ink droplets that land on one pixel. The inkjet head 1 may also be configured to change the amount of ink droplets that land on one pixel by changing the number of times the ink is ejected. In this way, the driver IC is an example of an application unit that applies a drive signal to the piezoelectric element 21.

[0054] For example, the driver IC includes a data buffer, a decoder, and a driver. The data buffer stores print data for each piezoelectric element 21 in chronological order. The decoder controls the driver for each piezoelectric element 21 based on the print data stored in the data buffer. The driver outputs a drive signal that operates each piezoelectric element 21 based on the control of the decoder. The drive signal is, for example, a voltage applied to each piezoelectric element 21.

[0055] The printed wiring board is a printing wiring assembly (PWA) on which various electronic components and connectors are mounted. The printed wiring board is connected to a control unit 150 of the inkjet recording apparatus 100.

[0056] In the inkjet head 1 configured as above, the nozzle plate 50, the frame portion 45, the manifold 40, and the vibration plate 30 form an ink flow path 35 having a plurality of pressure chambers 31 communicating with the nozzles 51, individual flow paths each composed of a throttle flow path 34 and an individual liquid chamber 33 communicating with the plurality of pressure chambers 31, and a common chamber 32 serving as a common flow path. For example, the common chamber 32 communicates with a cartridge, and ink is supplied to each pressure chamber 31 through the common chamber 32. All the piezoelectric elements 21 are connected by wiring so that a voltage can be applied thereto. In the inkjet head 1, when the control unit 150 applies a driving voltage to the electrodes 221 and 222 by the driver IC, the piezoelectric element 21 to be driven vibrates in the stacking direction, i.e., in the thickness direction of each piezoelectric layer 211. In other words, the piezoelectric element 21 vibrates vertically.

[0057] Specifically, the control unit 150 applies a driving voltage to the internal electrodes 221, 222 of the piezoelectric element 21 to be driven, selectively driving the piezoelectric element 21 to be driven. Then, the vibration plate 30 is deformed by combining the deformation in the tensile direction and the deformation in the compressive direction by the piezoelectric element 21 to be driven, and the volume of the pressure chamber 31 is changed, so that liquid is guided from the common chamber 32 and ejected from the nozzle 51.

[0058] An example of an inkjet recording device 100 including an inkjet head 1 will be described below with reference to Fig. 6. The inkjet recording device 100 includes a housing 111, a medium supply unit 112, an image forming unit 113, a medium discharge unit 114, a conveying device 115, and a control unit 150.

[0059] The inkjet recording device 100 is a liquid ejection device that performs an image formation process on paper P by ejecting liquid such as ink while transporting the paper P as a printing medium, which is the ejection target, along a predetermined transport path A from a medium supply section 112 through an image forming section 113 to a medium ejection section 114.

[0060] The housing 111 constitutes the outer shell of the inkjet recording apparatus 100. The housing 111 is provided at a predetermined location with an outlet for discharging the paper P to the outside.

[0061] The medium supply unit 112 includes a plurality of paper feed cassettes, and is configured to be able to hold a plurality of stacked sheets of paper P of various sizes.

[0062] The medium discharge unit 114 includes a paper discharge tray configured to be able to hold the paper P discharged from the discharge opening.

[0063] The image forming section 113 includes a support section 117 that supports the paper P, and a plurality of head units 130 that are disposed above the support section 117 so as to face the support section 117.

[0064] The support section 117 includes a conveyor belt 118 provided in a loop shape in a predetermined area where image formation is performed, a support plate 119 supporting the conveyor belt 118 from the back side, and a plurality of belt rollers 120 provided on the back side of the conveyor belt 118.

[0065] During image formation, the support section 117 supports the paper P on a holding surface, which is the upper surface of the conveyor belt 118, and conveys the paper P downstream by feeding the conveyor belt 118 at a predetermined timing by the rotation of the belt roller 120.

[0066] The head unit 130 includes multiple (four colors) inkjet heads 1, ink tanks 132 as liquid tanks mounted on each inkjet head 1, a connection flow path 133 connecting the inkjet heads 1 and the ink tanks 132, and a supply pump 134.

[0067] In this embodiment, the inkjet heads 1 are provided with four colors, cyan, magenta, yellow, and black, and ink tanks 132 that respectively contain ink of each color. The ink tanks 132 are connected to the inkjet heads 1 by connection channels 133.

[0068] In addition, a negative pressure control device such as a pump (not shown) is connected to the ink tank 132. Then, by controlling the negative pressure inside the ink tank 132 by the negative pressure control device according to the water head value between the inkjet head 1 and the ink tank 132, the ink supplied to each nozzle 51 of the inkjet head 1 is caused to form a meniscus of a predetermined shape.

[0069] The supply pump 134 is a liquid delivery pump constituted by, for example, a piezoelectric pump. The supply pump 134 is provided in a supply flow path. The supply pump 134 is connected to a drive circuit of the control unit 150 by wiring, and is configured to be controllable by a CPU (Central Processing Unit). The supply pump 134 supplies liquid to the inkjet head 1.

[0070] The conveying device 115 conveys the paper P along a conveying path A that extends from the medium supply unit 112 through the image forming unit 113 to the medium discharge unit 114. The conveying device 115 includes a plurality of guide plate pairs 121 and a plurality of conveying rollers 122 that are arranged along the conveying path A.

[0071] Each of the guide plate pairs 121 includes a pair of plate members disposed opposite each other with the paper P being transported therebetween, and guides the paper P along the transport path A.

[0072] The conveying rollers 122 are driven to rotate under the control of the control unit 150, thereby sending the paper P downstream along the conveying path A. Sensors for detecting the conveying status of the paper are disposed at various points along the conveying path A.

[0073] The control unit 150 includes a control circuit 151 such as a CPU which serves as a controller, a ROM (Read Only Memory) which stores various programs, a RAM (Random Access Memory) which temporarily stores various variable data, image data, etc., and an interface unit which inputs data from the outside and outputs data to the outside.

[0074] In the inkjet recording device 100 configured as above, when the control unit 150 detects a print instruction by a user operating an operation input unit in an interface, for example, the control unit 150 drives the conveying device 115 to convey the paper P and outputs a print signal to the head unit 130 at a predetermined timing to drive the inkjet head 1. As a discharge operation, the inkjet head 1 sends a drive signal to the driver IC by an image signal corresponding to image data, applies a drive voltage to the internal electrodes 221 and 222 to selectively drive the piezoelectric elements 21 to be discharged and vibrate them vertically in the stacking direction, and changes the volume of the pressure chambers 31 to discharge ink from the nozzles 51, forming an image on the paper P held on the conveying belt 118. As a liquid discharge operation, the control unit 150 drives the supply pump 134 to supply ink from the ink tank 132 to the common chamber 32 of the inkjet head 1.

[0075] Here, the driving operation for driving the inkjet head 1 will be described. The inkjet head 1 according to this embodiment includes piezoelectric elements 21 arranged opposite to the pressure chambers 31, and these piezoelectric elements 21 are connected by wiring so that a voltage can be applied thereto. The control unit 150 sends a driving signal to the driver IC by an image signal corresponding to image data, and applies a driving voltage to the internal electrodes 221, 222 of the piezoelectric element 21 to be driven, thereby selectively deforming the piezoelectric element 21 to be driven. Then, the volume of the pressure chamber 31 is changed by combining the deformation in the tensile direction and the deformation in the compressive direction of the vibration plate 30, thereby discharging liquid.

[0076] For example, the control unit 150 alternates between a pulling operation and a compressing operation. In the inkjet head 1, during pulling to increase the internal volume of the target pressure chamber 31, the piezoelectric element 21 to be driven is contracted, and the driving piezoelectric elements that are not the driving targets are not deformed. Also, during compression to decrease the internal volume of the target pressure chamber 31 in the inkjet head 1, the target driving piezoelectric element 21 is expanded, and the non-driven piezoelectric elements 22 are not deformed.

[0077] According to the inkjet head 1 and the inkjet recording device 100 of the above-mentioned embodiment, the width dimension of the long beam-like portion 463 can be secured by stacking the multiple flow path substrates 401, 402, and 403 and configuring the longest slit 4031 to be small. That is, by combining the multiple flow path substrates 401, 402, and 403 and securing the width dimension at the openings 4011, 4012, 4021, and 4022 with a short extension direction and narrowing the width of the openings with a long extension direction, the rigidity of each of the flow path substrates 401, 402, and 403 can be effectively secured. That is, the flow path substrates 401 and 402 can secure the rigidity by dividing the openings, and the flow path substrate 403 can secure the rigidity by narrowing the width of the slit 4031 that becomes the opening. Therefore, it is easier to secure the strength and maintain the fine flow path shape than, for example, forming a wide and long opening or groove in one flow path substrate. Therefore, it is possible to prevent the flow channel substrates 401, 402, and 403 from being deformed during cleaning or the like.

[0078] Furthermore, by narrowing the width of the slits 4031 that form the throttle flow path 34, strength can be ensured and the flow path shape can be narrowed, so that a narrower flow path can be effectively formed depending on the specifications.

[0079] Furthermore, since the slit 4031, which is the longest opening or groove, is formed in the flow path substrate 403 which is arranged opposite the highly rigid nozzle plate 50, it is easier to ensure stability and shape retention compared to, for example, a configuration in which openings are arranged opposite each other on both sides.

[0080] Furthermore, since the rigidity of the flow path can be increased, the number of substrates can be reduced, leading to cost reduction. For example, when thin plates of SUS are used as the flow path substrates 401, 402, and 403, chemical resistance and ink resistance can be ensured. On the other hand, when the material of 401, 402, and 403 is silicon, dry etching can be performed, and a flow path with high accuracy can be formed.

[0081] The present invention is not limited to the above-described embodiment, and in the implementation stage, the components can be modified and embodied without departing from the spirit of the invention.

[0082] For example, the specific configuration of the manifold 40 is not limited to the above. For example, although an example formed of three flow path substrates 401, 402, and 403 has been shown, the manifold 40 may be formed of two or four or more substrates. Furthermore, the shape of the openings in each of the flow path substrates 401 and 402 is not limited to the above embodiment.

[0083] 7, the flow path section 1040 may be composed of four flow path substrates 401, 402, 402, and 403. In these embodiments, the width of the long slit in the flow path substrate 403 having a long slit is narrowed, so that the strength of the beam-shaped member can be easily ensured and a fine flow path shape can be maintained. Therefore, deformation of the flow path substrate during cleaning, etc. can be prevented.

[0084] For example, in the above embodiment, the slits 4031 of the flow channel substrate 403 are openings that penetrate in the thickness direction, but the present invention is not limited to this. For example, at least a part of the slits may be blocked without penetrating in the thickness direction (stacking direction). The slits 4031 may be formed with a bottom by etching to the middle of the thickness direction (stacking direction) by half etching, leaving a part of the bottom wall.

[0085] Furthermore, for example, in the above embodiment, an example was shown in which the second openings 4012, 4022 and the slits 4031 are divided in the arrangement direction for each row of pressure chambers 31 to form individual liquid chambers 33, but this is not limited to this, and for example, multiple second openings 4012, 4022 and slits 4031 may be continuous in the arrangement direction to form a common flow path.

[0086] In the above embodiment, the flow path substrates 401 and 402 serving as the first flow path substrates have a plurality of openings 4011, 4012, 4021, and 4022, but the present invention is not limited to this. For example, the flow path substrates 401 and 402 serving as the first flow path substrates may have grooves that are at least partially blocked. For example, the flow path substrates 401 and 402 serving as the first flow path substrates may have grooves that are partially blocked and have openings that penetrate through the other parts, and the grooves of the first flow path substrates 401 and 402 and the slits 4031 of the flow path substrate 403 serving as the second flow path substrate are disposed opposite to each other and communicate with each other to form a predetermined flow path. In addition, the positions of the first flow path substrates 401, 402 and the second flow path substrate 403 in the stacking direction are not limited to those in the above embodiment, and can be appropriately changed. For example, the flow path substrates 401, 402 as the first flow path substrates may be located on the nozzle plate 50 side, and the flow path substrate 403 as the second flow path substrate may be located on the actuator section 20 side.

[0087] For example, in the above embodiment, a plurality of layers of piezoelectric members are stacked, and the piezoelectric element 21 is driven by longitudinal vibration (d33) in the stacking direction, but the present invention is not limited to this. For example, the present invention can be applied to a configuration in which the piezoelectric element 21 is composed of a single layer of piezoelectric member, and can also be applied to a configuration in which the piezoelectric element 21 is driven by lateral vibration (d31).

[0088] Furthermore, the specific configuration of the piezoelectric elements 21 and 22, the shape of the flow paths, and the configurations and positional relationships of various components including the manifold 40, the nozzle plate 50, and the frame portion 45 are not limited to the above examples, and can be modified as appropriate. Furthermore, the arrangement of the nozzles 51 and the pressure chambers 31 is not limited to the above examples. For example, the nozzles 51 may be arranged in two or more rows. Furthermore, dummy chambers may be formed between multiple pressure chambers 31.

[0089] Furthermore, the liquid to be ejected is not limited to ink for printing, but may be, for example, a device that ejects liquid containing conductive particles for forming a wiring pattern on a printed wiring board.

[0090] In addition, in the above embodiment, the inkjet head 1 is used in a liquid ejection device such as an inkjet recording device, but the present invention is not limited to this and can also be used in, for example, 3D printers, industrial manufacturing machines, and medical applications, enabling reduction in size, weight, and cost.

[0091] According to at least one of the embodiments described above, a desired flow path shape can be easily set.

[0092] Although several other embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0093] 1...inkjet head, 20...actuator section, 21...driven piezoelectric element, 22...non-driven piezoelectric element, 23...groove, 26...piezoelectric structure section, 30...diaphragm, 31...pressure chamber, 32...common chamber, 33...individual liquid chamber, 34...throttling flow path, 35...ink flow path, 40...manifold, 41...peripheral wall section, 42...partition wall section, 43...side wall section, 45...frame section, 50...nozzle plate, 51...nozzle, 70...driving circuit, 100...inkjet recording device, 111...housing, 112...medium supply section, 113...image forming section, 114...medium discharge section, 115...conveyor device, 117...support section, 118...conveyor belt, 119...support plate, 120...belt rod roller, 121...pair of guide plates, 122...conveyor roller, 130...head unit, 132...ink tank, 133...connecting flow path, 134...supply pump, 150...control unit, 151...control circuit, 211...piezoelectric layer, 221...internal electrode, 222...internal electrode, 223...external electrode, 224...external electrode, 301...vibration region, 302...support region, 303...opening, 401...flow path substrate, 402...flow path substrate, 403...flow path substrate, 461...beam-shaped portion, 462...beam-shaped portion, 463...beam-shaped portion, 1040...flow path portion, 4011...first opening, 4012...second opening, 4021...first opening, 4022...second opening, 4031...slit.

Claims

1. a nozzle plate having a plurality of nozzles for ejecting droplets; A flow path portion including a plurality of flow path substrates having openings or grooves and stacked together, the flow path being formed by the openings or the grooves; A liquid ejection head, wherein among the plurality of openings or grooves, the opening or groove that is longest in one direction has a width dimension intersecting the one direction and the stacking direction that is smaller than the other openings or grooves.

2. The opening or the groove that is the longest in one direction is a rectangular slit, The flow path portion is disposed on the nozzle plate, the flow path includes a plurality of pressure chambers communicating with the plurality of nozzles, and a plurality of individual flow paths communicating with the pressure chambers, The liquid ejection head according to claim 1 , further comprising a vibration plate disposed on the flow path portion on the opposite side to the nozzle plate.

3. The liquid ejection head according to claim 1 , wherein the opening or groove that is longest in the one direction is formed across both ends in the one direction of a flow path that is formed in a flow path structure in which a plurality of the flow path substrates are stacked.

4. The liquid ejection head according to claim 1 , wherein the opening or groove that is longest in the one direction is formed in the flow path substrate that is disposed opposite the nozzle plate.

5. 3. The liquid ejection head according to claim 2, wherein another flow path substrate arranged on top of the flow path substrate having the opening or groove that is the longest in the one direction has one or more openings that are connected to the opening or groove that is the longest in the one direction, and that are shorter in a first direction and have a larger width dimension than the opening or groove that is the longest in the one direction.

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