Liquid ejection head

Abstract

To provide a liquid discharge head capable of ensuring stable discharge characteristics.SOLUTION: A liquid discharge head is equipped with a plurality of side walls that are configured by a piezoelectric material and form a plurality of grooves alternately configuring a plurality of pressure chambers and a plurality of air chambers, a pair of extension walls extending from end portions of the pair of side walls in extension directions of the air chambers, and a partitioning wall portion that has a connection wall connecting the extension walls on the outer side than the end portions of the side walls, and block the end portions of the groove of the air chambers. The pressure chambers communicate with a nozzle discharging droplets.SELECTED DRAWING: Figure 5

Description

Technical Field

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

Background Art

[0002] In recent years, in inkjet heads, high productivity has been demanded, and issues such as high speed and increased droplet volume have arisen. For example, in a share mode share wall type inkjet head, the same drive column is shared by two pressure chambers, and a so-called 3-cycle drive in which 1 / 3 of a plurality of arranged chambers are simultaneously driven as pressure chambers is common. In addition, an independent drive head has been developed in which both sides of a pressure chamber to be driven are dummy pressure chambers and one pressure chamber is driven by two independent drive columns. For example, a structure has been developed in which a large number of grooves are formed in a piezoelectric body, the entrances and exits are blocked every other one, the grooves whose entrances and exits are not blocked are used as pressure chambers, and the blocked grooves are used as air chambers for independent drive.

[0003] In such an inkjet head, displacement vibration when driving a pressure chamber is transmitted to the ink in an adjacent pressure chamber through a wall that closes the air chamber, causing crosstalk.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem to be solved by the present invention is to provide a liquid ejection head capable of ensuring stable ejection characteristics.

Means for Solving the Problems

[0006] The liquid ejection head according to one embodiment is composed of a piezoelectric material, and includes a plurality of side walls that form a plurality of grooves alternately configuring a plurality of pressure chambers and a plurality of air chambers, A first common chamber arranged on one end side in the extending direction of the plurality of pressure chambers, and a second common chamber arranged on the other end side in the extending direction of the plurality of pressure chambers; a pair of extending walls respectively extending in the extending direction of the air chamber from the ends of a pair of the side walls that constitute both sides of the air chamber, and a connecting wall that connects the extending walls outside the ends of the side walls, and includes a partition wall portion that closes the end of the groove of the air chamber, and the pressure chamber communicates with a nozzle that ejects droplets. One end side in the extending direction opens to the first common chamber, and the other end side in the extending direction opens to the second common chamber.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

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Figure 4

Figure 5

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Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Best Mode for Carrying Out the Invention

[0008] Hereinafter, the configuration of an inkjet head 10, which is a liquid ejection head according to the first embodiment, will be described with reference to FIGS. 1 to 8. FIG. 1 is a perspective view showing the inkjet head according to the first embodiment, and FIG. 2 is an exploded perspective view of a part of the inkjet head. FIG. 3 is a perspective view showing an enlarged configuration of a part of the inkjet head, and FIGS. 4 to 7 are cross-sectional views showing an enlarged configuration of a part of the inkjet head. FIG. 8 is an explanatory diagram of the driving state. In the figure, X, Y, and Z respectively indicate a first direction, a second direction, and a third direction that are perpendicular to each other. In this embodiment, the description of the direction is based on the posture in which the parallel direction of the nozzles 28 and the pressure chambers 31 of the inkjet head 10 is along the X-axis, the extending direction of the pressure chambers 31 is along the Y-axis, and the liquid ejection direction is along the Z-axis, but it is not limited thereto.

[0009] As shown in FIGS. 1 to 7, the inkjet head 10 is a so-called side shooter type shared mode shared wall type inkjet head. The inkjet head 10 is a device for ejecting ink, and is mounted, for example, inside an inkjet printer. For example, the inkjet head 10 is an independently driven type inkjet head in which pressure chambers 31 and air chambers 32 are alternately arranged. The air chamber 32 is an air chamber to which no ink is supplied and does not include the nozzles 28.

[0010] The inkjet head 10 includes an actuator base 11, a nozzle plate 12, and a frame 13. The actuator base 11 is an example of a base material. An ink chamber 27 to which ink, which is an example of a liquid, is supplied is formed inside the inkjet head 10.

[0011] Furthermore, the inkjet head 10 includes components such as a circuit board 17 that controls the inkjet head 10 and a manifold 18 that forms a part of the path between the inkjet head 10 and the ink tank.

[0012] As shown in FIG. 2, the actuator base 11 includes a substrate 21 and a pair of actuators 22.

[0013] The substrate 21 is formed in a rectangular plate shape by ceramics such as alumina, for example. The substrate 21 has a flat mounting surface. A pair of actuators 22 are joined to the mounting surface of the substrate. A plurality of supply holes 25 and discharge holes 26 are formed in the substrate 21.

[0014] As shown in FIGS. 2 and 3, a pattern wiring 211 is formed on the substrate 21 of the actuator base 11. The pattern wiring 211 is formed by, for example, a nickel thin film. The pattern wiring 211 has a common pattern and individual patterns, and is configured in a predetermined pattern shape connected to an electrode layer 34 formed on the actuator 22. For example, the pattern wiring 211 is formed at a position avoiding the supply holes 25 and the discharge holes 26.

[0015] The supply holes 25 are provided side by side in the longitudinal direction of the actuator 22 at the center of the substrate 21 and between the pair of actuators 22. The supply holes 25 communicate with the ink supply portion of the manifold 18. The supply holes 25 are connected to the ink tank via the ink supply portion. The supply holes 25 supply the ink in the ink tank to the ink chamber 27.

[0016] The discharge holes 26 are provided in two rows with the supply holes 25 and the pair of actuators 22 interposed therebetween. The discharge holes 26 communicate with the ink discharge portion of the manifold 18. The discharge holes 26 are connected to the ink tank via the ink discharge portion. The discharge holes 26 discharge the ink in the ink chamber 27 to the ink tank.

[0017] A pair of actuators 22 are adhered to the mounting surface of the substrate 21. The pair of actuators 22 are provided on the substrate 21 in two rows with the supply holes 25 interposed therebetween. Each actuator 22 is formed by, for example, two plate-shaped piezoelectric bodies made of lead zirconate titanate (PZT). The two piezoelectric bodies are bonded together such that their polarization directions are opposite to each other in the thickness direction. The actuator 22 is adhered to the mounting surface of the substrate 21 by, for example, an epoxy-based adhesive having thermosetting properties. As shown in FIG. 2, the actuators 22 are arranged in parallel in the ink chamber 27 corresponding to the nozzles 28 arranged in two rows. The actuator 22 divides the ink chamber 27 into a first common chamber 271 in which the supply hole 25 opens and two second common chambers 272 in which the discharge holes 26 open.

[0018] The actuator 22 has a width in the short direction that gradually increases from the top side toward the substrate side. The cross-sectional shape along the direction (short direction) orthogonal to the longitudinal direction of the actuator 22 is formed in a trapezoidal shape. The side surface portion 221 of the actuator 22 has an inclined surface that is inclined with respect to the second direction and the third direction. The top of the actuator 22 is adhered to the nozzle plate 12. The actuator 22 includes a plurality of pressure chambers 31 and a plurality of air chambers 32. The actuator 22 has a plurality of side walls 33, and between the side walls 33, there are grooves that constitute the pressure chambers 31 and the air chambers 32. In other words, the side walls 33 are formed as driving elements between the grooves that form the pressure chambers 31 and the air chambers 32.

[0019] FIG. 4 is a partially enlarged plan view of one of the actuators 22 of the inkjet head 10 shown in FIG. 2. FIG. 5 is a cross-sectional view taken along line F5-F5 of the groove constituting the pressure chamber 31 of the inkjet head 10 shown in FIG. 4. And FIG. 6 is a cross-sectional view taken along line F6-F6 of the groove constituting the air chamber 32 of the inkjet head 10 shown in FIG. 4.

[0020] As shown in FIGS. 2, 5, and 6, the bottom surface of the groove and the main surface of the substrate 21 are connected by an inclined side surface portion 221. The pressure chambers 31 and the air chambers 32 are alternately arranged. The pressure chambers 31 and the air chambers 32 extend in directions intersecting the longitudinal direction of the actuator 22, respectively, and a plurality of them are arranged in parallel in the first direction (X-axis in the figure), which is the longitudinal direction of the actuator 22. In the present embodiment, for example, the groove 14 is configured such that the width dimension in the X direction is constant in the depth direction along the Z direction, and the cross section orthogonal to the extending direction of the groove 14, which is the Y direction, is rectangular.

[0021] Note that the shapes of the pressure chamber 31 and the air chamber 32 may be different. The side wall 33 is formed between the pressure chamber 31 and the air chamber 32, and deforms according to the drive signal to change the volume of the pressure chamber 31.

[0022] Electrode layers 34 are provided on the inner wall surfaces of the pressure chamber 31 and the air chamber 32 of the actuator base 11, and on the side surface portion 221, respectively. The electrode layer 34 is formed of a conductive film such as a nickel thin film, for example. The electrode layer 34 extends from the inner surface portion of the groove through the side surface portion 221 to the substrate 21 and is connected to the pattern wiring 211. For example, the electrode layer 34 is formed on at least one of the side surface portion and the bottom surface portion of the side wall 33.

[0023] The plurality of pressure chambers 31 communicate with the plurality of nozzles 28 of the nozzle plate 12 joined to the top. Both ends of the pressure chamber 31 in the second direction communicate with the ink chamber 27. That is, one end opens to the first common chamber 271 of the ink chamber 27, and the other end opens to the second common chamber 272 of the ink chamber 27. For this reason, ink flows into the pressure chamber 31 from one end and flows out from the other end. Also, ink may flow into the pressure chamber 31 from both ends.

[0024] As shown in FIGS. 3 and 6, one side of the air chamber 32 in the third direction (Z direction) is blocked by a nozzle plate 12 joined to the top. Also, the plurality of air chambers 32 are blocked at both ends in the second direction by a cover portion 23, for example. That is, cover portions 23 are disposed between the first common chamber 271 of the ink chamber 27 and the air chamber 32, and between the air chamber 32 and the second common chamber 272, and both ends of the air chamber 32 are separated from the ink chamber 27. For this reason, the air chamber 32 constitutes an air chamber into which ink does not flow.

[0025] For example, the cover portions 23 are respectively provided at both ends in the Y direction, which is the extending direction of each air chamber 32. The cover portion 23 has a partition wall portion 230 that connects the ends of the side walls 33 and separates the common chambers 271, 272 from the air chamber 32. For example, at least a part of the partition wall portion 230 is disposed outside the side wall 33 in the extending direction of the air chamber 32.

[0026] The partition wall portion 230 is configured to suppress the transmission of displacement vibration of the side wall 33. The partition wall portion 230 includes a pair of extending walls 231 extending in the extending direction of the air chamber 32, and a connecting wall 232 connecting the pair of extending walls 231. An air layer 321 is interposed between the pair of extending walls 231. That is, the pair of extending walls 231 are separated in the first direction (X direction) which is the deformation direction. The partition wall portion 230 has a bent portion and connects between the pair of side walls 33 in a roundabout manner with a connection distance longer than the distance between the pair of side walls 33. The partition wall portion 230 is elastically deformable and is configured to absorb the displacement vibration of the side wall 33. That is, the partition wall portion 230 is configured to have a longer connection distance for connecting the side walls 33 than a configuration in which the ends of the side walls 33 are connected by a flat plate-like member at the shortest distance. The wall length of the partition wall portion 230 is longer than the width dimension of the air chamber 32. The partition wall portion 230 is a wall-like member that passes outside the air chamber 32 in the extending direction from the ends of the side walls 33 and closes the ends of the air chamber 32, and has a bent portion that bends in a U shape or a C shape.

[0027] The pair of extending walls 231 are wall members that extend from a pair of side walls 33 that constitute both side portions of the target air chamber 32 in the extending direction of the air chamber 32. The extending walls 231 constitute an elastically deformable portion that can be deformed by the displacement vibration of the side walls 33. An air layer 321 connected to the air chamber 32 is interposed between the pair of extending walls 231. In other words, the air chamber 32 is expanded outside the end portions of the side walls 33 by the pair of extending walls 231.

[0028] The connecting wall 232 connects the outer end portions of the pair of extending walls 231 at a position away from the side walls 33. The connecting wall 232 is a wall member that extends in a direction orthogonal to the longitudinal direction of the air chamber 32 and in the arrangement direction of a plurality of grooves. The connecting wall 232 may be a flat plate-shaped wall member arranged outside the end portions of the side walls 33, or may be a curved wall.

[0029] Also, the partition wall portion 230 is made of a material having a lower hardness than the piezoelectric material. For example, the partition wall portion 230 is made of a resin material softer than the side walls 33. As an example, the partition wall portion 230 is made of a photosensitive resin material. For example, after applying a photosensitive resin to both end portions of the air chamber 32, the partition wall portion 230 is formed by exposure curing into its shape.

[0030] When the side wall 33 is displaced in the X direction, the partition wall portion 230 configured as described above can absorb the displacement vibration of the side wall 33 by elastically deforming so that the extending walls 231 are displaced in the X direction, and suppress the transmission of vibration from one side wall 33 to the other side wall 33. That is, by interposing a pair of extending walls 231 spaced apart from each other in the X direction, which is the vibration direction of the side wall 33, the transmission of vibration of one side wall 33 to the other side wall 33 can be suppressed.

[0031] The nozzle plate 12 is formed of, for example, a rectangular film made of polyimide. The nozzle plate 12 faces the mounting surface of the actuator base 11. A plurality of nozzles 28 penetrating the nozzle plate 12 in the thickness direction are formed in the nozzle plate 12.

[0032] A plurality of nozzles 28 are provided in the same number as the pressure chambers 31 and are arranged to face the pressure chambers 31 respectively. The nozzles 28 are arranged in a plurality along the first direction (X direction) and are arranged in two rows corresponding to the pair of actuators 22. Each nozzle 28 is configured in a cylindrical shape with its axis extending in the third direction. For example, even if the diameter of the nozzle 28 is constant, it may have a shape with a reduced diameter from the central portion to the tip portion. The nozzle 28 is arranged to face the middle portion in the extending direction of the pressure chamber 31 formed in the pair of actuators 22 and communicates with the pressure chamber 31 respectively. The nozzle 28 is arranged one by one at positions corresponding between both ends of each pressure chamber 31, for example, at the central portion in the longitudinal direction.

[0033] The frame 13 is formed in a rectangular frame shape by, for example, a nickel alloy. The frame 13 is interposed between the mounting surface of the actuator base 11 and the nozzle plate 12. The frame 13 is adhered to the mounting surface of the actuator base 11 and the nozzle plate 12 respectively. That is, the nozzle plate 12 is attached to the actuator base 11 via the frame 13.

[0034] The manifold 18 is joined to the side of the actuator base 11 opposite to the nozzle plate 12. Inside the manifold 18, an ink supply portion which is a flow path communicating with the supply hole 25 and an ink discharge portion which is a flow path communicating with the discharge hole 26 are formed.

[0035] The circuit board 17 shown in FIG. 1 is a film carrier package (FCP). The circuit board 17 has a resin film 51 having flexibility and a plurality of wirings formed thereon, and a drive IC 52 connected to the plurality of wirings of the film 51. The drive IC 52 is electrically connected to the electrode layer 34 via the wirings and pattern wirings 211 of the film 51.

[0036] Inside the inkjet head 10 configured as described above, an ink chamber 27 is formed, surrounded by the actuator base 11, the nozzle plate 12, and the frame 13. That is, the ink chamber 27 is formed between the actuator base 11 and the nozzle plate 12. For example, the ink chamber 27 is partitioned into three sections in the second direction (Y direction) by two actuators 22, and has two second common chambers 272 as common chambers where the discharge holes 26 open, and a first common chamber 271 as a common chamber where the supply holes 25 open. The first common chamber 271 and the second common chambers 272 communicate with a plurality of pressure chambers 31.

[0037] FIG. 7 is an enlarged cross-sectional view of a portion of the inkjet head 10 of FIG. 2 cut along F7-F7 in the longitudinal direction. FIG. 8 is a partially enlarged cross-sectional view showing an example of a state in which the side wall 33 of FIG. 7 is deformed in the share mode.

[0038] In the inkjet head 10 configured as described above, ink circulates between the ink tank and the ink chamber 27 through the supply holes, the pressure chambers, and the discharge holes. For example, a drive voltage is applied to the electrode layer 34 of the pressure chamber 31 via the wiring of the film 51 by the drive IC 52 according to a signal input from the control unit of the inkjet printer, creating a potential difference between the electrode layer 34 of the pressure chamber 31 and the electrode layer 34 of the air chamber 32, thereby selectively deforming the side wall 33 in the share mode. By deforming the side wall 33 formed between the pressure chamber 31 and the air chamber 32 in response to a drive signal, the volume of the pressure chamber 31 is changed.

[0039] As shown by the solid line in FIG. 8, when the side wall 33 is deformed in the share mode, the volume of the pressure chamber 31 provided with the electrode layer 34 increases and the pressure decreases. As a result, ink from the ink chamber 27 flows into the pressure chamber 31.

[0040] With the volume of the pressure chamber 31 increased, the driving IC 52 applies a driving voltage of reverse potential to the electrode layer 34 of the pressure chamber 31. As a result, as shown by the two-dot chain line in FIG. 8, the side wall 33 undergoes shear mode deformation, reducing the volume of the pressure chamber 31 where the electrode layer 34 is provided and increasing the pressure. Thereby, the ink in the pressure chamber 31 is pressurized and ejected from the nozzle 28.

[0041] A method for manufacturing the inkjet head 10 will be described. First, a piezoelectric member having a plurality of grooves is attached to a plate-shaped substrate 21 with an adhesive or the like, and machining using a dicing saw, a slicer, or the like is performed to form an actuator base 11 having a predetermined outer shape. For example, a block-shaped base member having a thickness for a plurality of sheets may be formed in advance and then divided to manufacture a plurality of actuator bases 11 having a predetermined shape.

[0042] Subsequently, an electrode layer 34 and a pattern wiring 211 are formed on the inner surface of the groove forming the pressure chamber 31 and the air chamber 32 and the surface of the substrate 21. Thus, the electrode layer 34 and the pattern wiring 211 are formed at predetermined positions on the surface of the actuator base 11, respectively.

[0043] Subsequently, by forming a cover portion 23 at the end of the air chamber 32, both ends of the air chamber 32 are closed. For example, the groove forming the air chamber 32 is filled with a photosensitive resin, and the target portion having a detour shape is cured to form the cover portion 23. Alternatively, after curing the photosensitive resin, the portion to become the air layer 321 is removed to form a slit-shaped air layer 321, and the photosensitive resin layer is formed in a U shape, thereby forming the cover portion 23.

[0044] Then, the actuator base 11 is assembled to the manifold 18, and the frame 13 is attached to one surface of the substrate 21 of the actuator base 11 with a thermoplastic resin adhesive sheet.

[0045] Then, polish so that the assembled frame 13, the top of the side wall 33 of the actuator 22, and the surface of the protrusion 241 on the nozzle plate 12 side are flush. Then, adhere and attach the nozzle plate 12 to the polished surfaces of the top of the side wall 33, the frame 13, and the protrusion 241. At this time, position the nozzle 28 so that it faces the pressure chamber 31. Further, as shown in FIG. 1, by connecting the drive IC 52 and the circuit board 17 to the pattern wiring 211 formed on the main surface of the substrate 21 via a flexible printed circuit board, the inkjet head 10 is completed.

[0046] An example of an inkjet printer 100 including the inkjet head 10 will be described below with reference to FIG. 12. The inkjet printer 100 includes a housing 111, a medium supply unit 112, an image forming unit 113, a medium discharge unit 114, a conveyance device 115, and a control unit 116.

[0047] The inkjet printer 100 is a liquid ejection device that performs an image forming process on a recording medium such as a sheet of paper P by ejecting a liquid such as ink while conveying the sheet of paper P as a recording medium to be ejected along a predetermined conveyance path A that extends from the medium supply unit 112 through the image forming unit 113 to the medium discharge unit 114.

[0048] The housing 111 constitutes the outer shell of the inkjet printer 100. A discharge port for discharging the sheet of paper P to the outside is provided at a predetermined location on the housing 111.

[0049] The medium supply unit 112 includes a plurality of paper feed cassettes and is configured to be able to stack and hold a plurality of sheets of paper P of various sizes.

[0050] The medium discharge unit 114 includes a paper discharge tray configured to be able to hold the sheet of paper P discharged from the discharge port.

[0051] The image forming unit 113 includes a support unit 117 that supports the sheet of paper P and a plurality of head units 130 that are disposed opposite each other above the support unit 117.

[0052] The support unit 117 includes a conveyance belt 118 provided in a loop shape in a predetermined area where image formation is performed, a support plate 119 that supports the conveyance belt 118 from the back side, and a plurality of belt rollers 120 provided on the back side of the conveyance belt 118.

[0053] During image formation, the support unit 117 supports the sheet P on the holding surface, which is the upper surface of the conveyance belt 118, and conveys the sheet P to the downstream side by sending the conveyance belt 118 at a predetermined timing by the rotation of the belt roller 120.

[0054] The head unit 130 includes a plurality (four colors) of inkjet heads 10, ink tanks 132 as liquid tanks respectively mounted on each inkjet head 10, connection channels 133 that connect the inkjet heads 10 and the ink tanks 132, and a circulation pump 134 that is a circulation unit. The head unit 130 is a circulation type head unit that constantly circulates liquid in the ink tank 132, the pressure chamber 31, the air chamber 32, and the ink chamber 27 formed inside the inkjet head 10.

[0055] In the present embodiment, four-color inkjet heads 10 of cyan, magenta, yellow, and black, and ink tanks 132 that store the inks of these respective colors are provided. The ink tanks 132 are connected to the inkjet heads 10 by connection channels 133. The connection channels 133 include a supply channel connected to the supply port of the inkjet head 10 and a recovery channel connected to the discharge port of the inkjet head 10.

[0056] Further, a negative pressure control device such as a pump (not shown) is connected to the ink tank 132. Then, corresponding to the head values of the inkjet head 10 and the ink tank 132, the negative pressure control device controls the inside of the ink tank 132 to be under negative pressure, thereby forming a meniscus of a predetermined shape for the ink supplied to each nozzle 28 of the inkjet head 10.

[0057] The circulation pump 134 is a liquid delivery pump composed of, for example, a piezoelectric pump. The circulation pump 134 is provided in the supply flow path. The circulation pump 134 is connected to the drive circuit of the control unit 116 by wiring and is configured to be controllable under the control of a CPU (Central Processing Unit). The circulation pump 134 circulates the liquid in a circulation flow path including the inkjet head 10 and the ink tank 132.

[0058] The conveyance device 115 conveys the paper P along a conveyance path A extending from the medium supply unit 112 through the image forming unit 113 to the medium discharge unit 114. The conveyance device 115 includes a plurality of pairs of guide plates 121 arranged along the conveyance path A and a plurality of conveyance rollers 122.

[0059] Each of the plurality of pairs of guide plates 121 includes a pair of plate members arranged to face each other with the conveyed paper P sandwiched therebetween, and guides the paper P along the conveyance path A.

[0060] The conveyance roller 122 is driven to rotate under the control of the control unit 116, and sends the paper P downstream along the conveyance path A. Sensors for detecting the conveyance state of the paper are arranged at various positions in the conveyance path A.

[0061] The control unit 116 includes a control circuit such as a CPU which is a controller, a ROM (Read Only Memory) for storing various programs, etc., a RAM (Random Access Memory) for temporarily storing various variable data and image data, etc., and an interface unit for inputting data from the outside and outputting data to the outside.

[0062] In the inkjet printer 100 configured as described above, when the control unit 116 detects a print instruction by the operation of the operation input unit at the interface, for example, it drives the conveyance device 115 to convey the paper P and outputs a print signal to the head unit 130 at a predetermined timing to drive the inkjet head 10. As a discharge operation, the inkjet head 10 sends a drive signal to the drive IC 52 according to an image signal corresponding to the image data, applies a drive voltage to the electrode layer 34 of the pressure chamber 31 through the wiring, selectively drives the side wall 33 of the actuator 22, and discharges the ink as droplets from the nozzle 28 to form an image on the paper P held on the conveyance belt 118. Further, as a liquid discharge operation, the control unit 116 drives the circulation pump 134 to circulate the liquid in the circulation path passing through the ink tank 132 and the inkjet head 10. By the circulation operation, the ink in the ink tank 132 is supplied from the ink tank 132 to the first common chamber 271 of the ink chamber 27 through the ink supply portion of the manifold 18 and the supply hole 25 when the circulation pump 134 is driven. This ink is supplied to the plurality of pressure chambers 31 of the pair of actuators 22. The ink flows into the second common chamber 272 of the ink chamber 27 through the pressure chamber 31. This ink is discharged from the discharge hole 26 to the ink tank 132 through the ink discharge portion of the manifold 18.

[0063] According to the above-described embodiments, so-called crosstalk can be suppressed, and the ejection performance can be easily maintained. According to the above embodiments, by being blocked by the partition portion 230 having a pair of extending walls 231 extending in the direction of the air chamber 32, the transmission of displacement vibration between the plurality of side walls 33 can be suppressed. For example, by elastic deformation of the extending wall 231 extending in the extending direction of the air chamber 32 in the partition portion 230, the displacement vibration can be attenuated. Therefore, when driving the pressure chamber 31 in the actuator 22, the displacement vibration of the side wall 33 is transmitted to the ink in another adjacent pressure chamber 31, so-called crosstalk that affects the pressure of the ink in the pressure chamber can be suppressed, and the ejection performance can be easily maintained. In addition, with a connection distance longer than the linear distance between the ends of the plurality of side walls 33, the partition portion 230 connecting between the side walls 33 increases the effect of vibration attenuation in the partition portion 230, and the transmission of displacement vibration can be suppressed.

[0064] FIG. 9 is an explanatory diagram showing the vibration state of the side wall 33 during driving for the inkjet head 10 according to the present embodiment and the inkjet head 1010 according to Comparative Example 1. As shown in FIG. 9, the inkjet head 1010 according to Comparative Example 1 has a configuration in which the space between the side walls 33 is connected by a flat cover portion 123 at the shortest distance. The cover portion 123 of the inkjet head 1010 does not deform when the side wall 33 is displaced and vibrated. Therefore, in the inkjet head 1010, the displacement vibration of the side wall 33 when driving the pressure chamber 31 propagates through the cover portion 123, and the displacement vibration is transmitted to the adjacent side wall 33, so that crosstalk that affects the pressure of the ink in another adjacent pressure chamber 31 is likely to occur. On the other hand, in the inkjet head 10, when the side wall 33 is displaced and vibrated, the displacement vibration can be attenuated by elastic deformation of the extending wall 231. Therefore, crosstalk can be suppressed.

[0065] FIG. 10 is a graph showing the relationship between the Young's modulus of the partition wall portion, the position of the partition wall portion, the length of the extending wall 231 where the partition wall portion extends outward from the side wall 33, and crosstalk. The configuration of the inkjet head 10 of the present embodiment corresponds to a value greater than 0 μm in FIG. 10. It can be seen that the crosstalk can be reduced as the position of the partition wall portion is further outside the groove (the longer the extending wall 231 is). The configuration of the inkjet head 1010 of Comparative Example 1 corresponds to the position of 0 μm in FIG. 10.

[0066] The inkjet head 2010 according to Comparative Example 2 shown in FIG. 11 corresponds to a position less than 0 μm (negative value) in FIG. 10, and the cover portion 123 is also formed in the groove of the air chamber 32. The longer the length of the cover portion 123 formed in the groove of the air chamber 32 is, the easier it is for the displacement vibration of the side wall 33 to be transmitted to the adjacent side wall 33 through the cover portion 123 in the groove of the air chamber 32, and the greater the influence of crosstalk becomes. In the inkjet head 10 according to the present embodiment, the partition wall portion 230 protrudes outside the groove, and the extending wall 231 relaxes the displacement vibration of the side wall 33 by elastic deformation, so that the crosstalk can be reduced more than that of the inkjet heads of Comparative Examples 1 and 2.

[0067] That is, in the inkjet head 10 according to the present embodiment, the partition wall portion 230 has the extending wall 231 and the connecting wall 232, and when the side wall 33 undergoes displacement vibration, the partition wall portion 230 has an elastically deformable shape, so that the displacement vibration of the side wall 33 is reduced, and the transmission of vibration to the adjacent pressure chamber can be suppressed. Further, according to the inkjet head 10, since the connection distance between the adjacent side walls 33 of the partition wall portion 230 is long, the effect of attenuating the displacement vibration in the partition wall portion 230 can be enhanced. Also, in the inkjet head 10, since the partition wall portion 230 is made of a resin material softer than the piezoelectric member, an effect of attenuating vibration can be obtained.

[0068] Note that the present invention is not limited to the above-described embodiment as it is, and at the implementation stage, the components can be modified and embodied without departing from the gist thereof.

[0069] For example, although the partition portion 230 having a bent portion and composed of a protruding wall and an extending wall has been shown, the present invention is not limited thereto. For example, it may have a configuration having a curved portion that curves in a U shape.

[0070] In the above embodiment, an example in which the actuator 22 having a plurality of grooves is arranged on the main surface portion of the substrate 21 has been shown, but the present invention is not limited thereto. For example, the actuator may be provided on the end face of the substrate 21. Further, the number of nozzle rows is not limited to the above embodiment, and may be configured to have one row or three or more rows.

[0071] In the above embodiment, the actuator base 11 having a laminated piezoelectric body made of the piezoelectric member 131 provided on the substrate 21 has been exemplified, but the present invention is not limited thereto. For example, the actuator base 11 may be formed only of the piezoelectric member without using a substrate. Further, instead of using two piezoelectric members, a single piezoelectric member may be used. Also, the supply side and the discharge side may be reversed, or may be configured to be switchable.

[0072] In the above embodiment, as an example, a circulation type inkjet head in which one side of the pressure chamber 31 is the supply side, the other side is the discharge side, and the first common chamber fluid flows in from one side of the pressure chamber and out from the other side has been exemplified, but the present invention is not limited thereto. For example, a non-circulation type may be used. Further, for example, the common chambers on both sides of the pressure chamber 31 may be the supply sides, and a configuration in which fluid flows in from both sides may be used. That is, a configuration in which fluid flows in from both sides of the pressure chamber 31 and flows out from the nozzle 28 disposed at the center of the pressure chamber 31 may be used. Also, the shapes of the cover portions 23 formed at both ends may be different from each other.

[0073] Further, for example, the liquid to be ejected is not limited to the printing ink, and for example, an apparatus that ejects a liquid containing conductive particles for forming a wiring pattern of a printed wiring board may be used.

[0074] In addition, in the above-described embodiment, the inkjet head has been described as an example used in a liquid ejection device such as an inkjet printer, but the present invention is not limited thereto. For example, it can also be used in a 3D printer, an industrial manufacturing machine, or a medical application, and can be made smaller, lighter, and less costly.

[0075] According to at least one of the embodiments described above, it is possible to provide a liquid ejection head capable of ensuring stable ejection characteristics and a method for manufacturing the liquid ejection head.

[0076] In addition, although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof. The following is an appended description equivalent to the invention described in the claims of the present application at the time of filing. (1) A plurality of side walls made of a piezoelectric material and forming a plurality of grooves that alternately form a plurality of pressure chambers and a plurality of air chambers; A pair of extending walls extending in the extending direction of the air chamber from the ends of a pair of the side walls constituting both sides of the air chamber, and a connecting wall connecting the extending walls outside the ends of the side walls, and a partition portion closing the end of the groove of the air chamber; The pressure chamber is a liquid discharge head communicating with a nozzle for discharging liquid droplets. (2) The liquid discharge head according to (1), wherein the extending wall extends in a direction orthogonal to the vibration direction of the side wall. (3) The partition portion has a bent portion. A space is provided between the pair of extending walls. The liquid discharge head according to (1) or (2), wherein the connecting wall connects the pair of extending walls at a position away from the side wall. (4) The liquid discharge head according to any one of (1) to (3), wherein the partition portion is made of a material having a lower hardness than the piezoelectric material. (5) The liquid discharge head according to any one of (1) to (4), wherein the partition portion is made of a photosensitive resin material.

Explanation of Reference Numerals

[0077] 10…Inkjet head, 11…Actuator base, 12…Nozzle plate, 13…Frame, 17…Circuit board, 18…Manifold, 21…Substrate, 22…Actuator, 23…Cover part, 230…Partition part, 231…Extended wall, 232…Connection wall, 321…Air layer, 25…Supply hole, 26…Discharge hole, 27…Ink chamber, 31…Pressure chamber, 32…Air chamber, 33…Side wall, 34…Electrode layer, 51…Film, 52…Drive IC, 100…Inkjet printer, 111…Housing, 112…Media supply unit, 113…Image forming unit, 114…Media discharge unit, 115…Conveyor, 116…Control unit, 117…Support unit, 118…Conveyor belt, 119…Support plate, 120…Belt roller, 121…Pair of guide plates, 122…Conveyor roller, 130…Head unit, 132…Ink tank, 133…Connection flow path, 134…Circulation pump, 211…Pattern wiring, 221…Side surface part, 271…First common chamber, 272…Second common chamber.

Claims

1. A plurality of side walls made of a piezoelectric material and forming a plurality of grooves that alternately form a plurality of pressure chambers and a plurality of air chambers; A first common chamber arranged on one end side in the extending direction of the plurality of pressure chambers; A second common chamber arranged on the other end side in the extending direction of the plurality of pressure chambers; A pair of extending walls extending in the extending direction of the air chamber from the ends of a pair of the side walls that constitute both sides of the air chamber, and a connecting wall that connects the extending walls outside the ends of the side walls, and a partition wall portion that closes the ends of the grooves of the air chamber; The pressure chamber communicates with a nozzle that discharges droplets, one end side in the extending direction opens to the first common chamber, and the other end side in the extending direction opens to the second common chamber; A liquid ejection head.

2. The liquid ejection head according to claim 1, wherein the extending wall extends in a direction orthogonal to the vibration direction of the side wall.

3. The partition wall portion has a bent portion; A space is provided between the pair of extending walls; The liquid ejection head according to claim 1 or 2, wherein the connecting wall connects the pair of extending walls at a position away from the side wall.

4. The liquid ejection head according to any one of claims 1 to 3, wherein the partition wall portion is made of a material having a lower hardness than the piezoelectric material.

5. The liquid ejection head according to any one of claims 1 to 4, wherein the partition wall portion is made of a photosensitive resin material.

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