Liquid ejection head

Abstract

To provide a liquid ejection head which can secure stable ejection characteristics.SOLUTION: A liquid ejection head according to an embodiment comprises an actuator, common chambers and a cover portion. The actuator has: a plurality of grooves constituting a plurality of pressure chambers communicated with nozzles, and a plurality of dummy chambers; and side walls. The common chambers are communicated with both ends of the plurality of pressure chambers. The cover portion has a throttling port which blocks portions of communication ports through which the pressure chambers are communicated with the common chambers at both end parts of the pressure chambers and communicates with the pressure chambers, and which is larger in fluid resistance than the insides of the pressure chambers. The cover portion has, in one body, first sites formed while superimposed on the side walls and arranged in the grooves and second sites formed outside the grooves in a first direction, wherein a dimension, in an extending direction, of the pressure chambers of the first sites is above 50% of a dimension, in the extending direction, of the pressure chambers of the cover portion.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, a share mode shared wall type inkjet head has high power and is suitable for ejecting high-viscosity ink and large droplets. In a share mode shared wall type inkjet head, the same drive column is shared by two pressure chambers, and a so-called 3-cycle drive is generally used in which 1 / 3 of a plurality of arranged chambers are simultaneously driven as pressure chambers. In addition, an independent drive head has been developed in which both sides of the 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, after an ink droplet is ejected, ink is supplied from a common liquid chamber to the pressure chamber. At this time, a phenomenon occurs in which the nozzle overshoots and the meniscus swells. The smaller the fluid resistance of the flow path from the common liquid chamber to the nozzle, the greater the overshoot. If this overshoot does not subside, the meniscus cannot eject in a stable state. Therefore, in order to increase the speed of an inkjet head, it is required to quickly converge the swelling of the meniscus and ensure stable ejection characteristics.

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 Problem

[0006] The liquid ejection head according to one embodiment is of a side shooter type and includes an actuator, a common chamber, and a cover portion. The actuator has a plurality of grooves that form a plurality of pressure chambers communicating with a plurality of nozzles for ejecting liquid and a plurality of dummy chambers disposed between the plurality of pressure chambers, and side walls formed between the plurality of grooves and configured to change the volume of the pressure chambers in response to a drive signal. The common chamber communicates with both ends of the plurality of pressure chambers. The cover portion has a throttle port that closes a part of the communication port where the pressure chamber communicates with the common chamber at both end portions of the pressure chamber, communicates with the pressure chamber, and has a greater fluid resistance than inside the pressure chamber. The cover portion integrally has a first portion formed to overlap the side wall and disposed in the groove and the groove and a second portion formed outside the first portion. throughout the depth direction of the pressure chamber The dimension of the first portion in the extending direction of the pressure chamber is 50% or more of the dimension of the cover portion in the extending direction of the pressure chamber.

Brief Description of the Drawings

[0007] [Fig. 1] Perspective view showing an inkjet head according to an embodiment. [Fig. 2] Exploded perspective view showing a partial configuration of an inkjet head according to an embodiment. [Fig. 3] Cross-sectional view showing an enlarged partial configuration of the inkjet head. [Fig. 4] Cross-sectional view showing an enlarged partial configuration of the inkjet head. [Fig. 5] Explanatory view showing the configuration of the throttle portion of the inkjet head according to the first embodiment. [Fig. 6] Explanatory view showing the configuration of the throttle portion of the inkjet head according to Comparative Example 1. [Fig. 7] Graph showing the measured values of the dimensions of the throttle part of the inkjet head according to the first embodiment and Comparative Example 1. [Fig. 8] Explanatory drawing showing the configuration of the throttle part of the inkjet head according to the second embodiment. [Fig. 9] Explanatory drawing showing the configuration of the throttle part of the inkjet head according to the third embodiment. [Fig. 10] Explanatory drawing showing the configuration of the throttle part of the inkjet head according to the fourth embodiment. [Fig. 11] Explanatory drawing showing the configuration of the throttle part of the inkjet head according to Comparative Example 2. [Fig. 12] Explanatory drawing of the inkjet head according to Test Example 1 and Test Example 2. [Fig. 13] Graph showing the ejection speed of the inkjet head according to Test Example 1. [Fig. 14] Graph showing the ejection speed of the inkjet head according to Test Example 2. [Fig. 15] Graph showing the meniscus recovery characteristics of the inkjet head according to Test Example 1 and Test Example 2. [Fig. 16] Explanatory drawing of the end shooter inkjet head according to Test Example 1 and Test Example 3. [Fig. 17] Graph showing the drive waveforms of the inkjet head according to Test Example 1 and Test Example 3. [Fig. 18] Graph showing the nozzle flow rate vibration of the inkjet head according to Test Example 1 and Test Example 3. [Fig. 19] Graph showing the ejection volume of the inkjet head according to Test Example 1 and Test Example 3. [Fig. 20] Graph showing the meniscus recovery characteristics of the inkjet head according to Test Example 1 and Test Example 3. [Fig. 21] Schematic diagram showing the inkjet printer according to the embodiment.

Modes for Carrying Out the Invention

[0008] Hereinafter, the configuration of the inkjet head 10, which is a liquid ejection head according to the first embodiment, will be described with reference to FIGS. 1 to 11. 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. FIGS. 3 and 4 are cross-sectional views showing an enlarged configuration of a part of the inkjet head. FIGS. 5 and 6 are explanatory views of the throttle portions of the inkjet heads according to the first embodiment and Comparative Example 1, and FIG. 7 is a graph showing the measured values of the throttle portions of the first embodiment and Comparative Example 1. FIG. 8 is an explanatory view showing the configuration of the throttle portion according to the second embodiment, FIG. 9 is an explanatory view showing the configuration of the throttle portion according to the third embodiment, and FIG. 10 is an explanatory view showing the configuration of the throttle portion according to the fourth embodiment. FIG. 11 is an explanatory view showing the configuration of the throttle portion according to Comparative Example 2. In the figures, X, Y, and Z respectively indicate the first direction, the second direction, and the third direction that are orthogonal to each other. In this embodiment, the description of the direction is given 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 to this.

[0009] As shown in FIGS. 1 to 4, 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 dummy chambers 32 are alternately arranged. The dummy chamber 32 is an air chamber to which no ink is supplied and does not include a nozzle 28.

[0010] The inkjet head 10 includes an actuator base 11, a nozzle plate 12, and a frame 13. An ink chamber 27 into which ink, which is an example of a liquid, is supplied is formed inside the actuator base 11 of 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, a pair of actuator members 22, and a cover portion 23.

[0013] The substrate 21 is an example of a base material and 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 actuator members 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 FIG. 2, 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 that is connected to the electrode layer 34 formed on the actuator member 22.

[0015] The supply holes 25 are provided side by side in the longitudinal direction of the actuator member 22 at the center of the substrate 21 and between the pair of actuator members 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 actuator members 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 actuator members 22 are adhered to the mounting surface of the substrate 21. The pair of actuator members 22 are provided on the substrate 21 in two rows with the supply holes 25 interposed therebetween. Each actuator member 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 member 22 is adhered to the mounting surface of the substrate 21 with, for example, an epoxy-based adhesive having thermosetting properties. As shown in FIG. 2, the actuator members 22 are arranged in parallel in the ink chamber 27 corresponding to the nozzles 28 arranged in two rows. The actuator member 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 pair of actuator members 22 are provided with their longitudinal directions along the first direction, and a cross-section orthogonal to the first direction is formed in a trapezoidal shape. The side surface portion 221 of the actuator member 22 has an inclined surface that is inclined with respect to the second direction and the third direction. That is, the actuator member 22 is configured to have a trapezoidal shape in a cross-sectional view orthogonal to the second direction. The top portion of the actuator member 22 is adhered to the nozzle plate 12. The actuator member 22 includes a plurality of pressure chambers 31 and a plurality of dummy chambers 32. The actuator member 22 has a plurality of side walls 33, and between the side walls 33, there are grooves that form the pressure chambers 31 and the dummy 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 dummy chambers 32. The plurality of pressure chambers 31 and the dummy chambers 32 are formed by grooves that open at both ends in the second direction and one side in the third direction.

[0019] As shown in FIGS. 1 to 4, the bottom surface portion of the groove and the main surface of the substrate 21 are connected by the inclined side surface portion 221. The pressure chambers 31 and the dummy chambers 32 are arranged alternately. The pressure chambers 31 and the dummy chambers 32 each extend in a direction intersecting the longitudinal direction of the actuator member 22, 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 member 22.

[0020] Note that the shape of the pressure chamber 31 and the shape of the dummy chamber 32 may be different. The side wall 33 is formed between the pressure chamber 31 and the dummy chamber 32, and changes its volume by deforming according to the drive signal, thereby changing the volume of the pressure chamber 31.

[0021] 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 in from one end of the pressure chamber 31 and flows out from the other end. At both ends of the pressure chamber 31, throttle portions 240 are formed with a larger fluid resistance than inside the pressure chamber 31.

[0022] One side of the dummy chamber 32 in the third direction is blocked by the nozzle plate 12 joined to the top 222. Also, both ends of the plurality of dummy chambers 32 in the second direction are blocked by the cover portion 23, for example. That is, cover portions 23 are arranged between the first common chamber 271 of the ink chamber 27 and the inlet of the dummy chamber 32, and between the outlet of the dummy chamber 32 and the second common chamber 272, respectively, and both ends of the dummy chamber 32 are separated from the ink chamber 27. For this reason, the dummy chamber 32 constitutes an air chamber into which ink does not flow.

[0023] Electrode layers 34 are provided in the pressure chamber 31 and the dummy chamber 32 of the actuator base 11, respectively. The electrode layer 34 is formed of, for example, a nickel thin film. The electrode layer 34 reaches from the inner surface portion of the groove onto the substrate 21 and is connected to the pattern wiring 211. The electrode layer 34 is formed on the inner wall of the groove. For example, the electrode layer 34 is formed on the side surface portion and the bottom surface portion of the side wall 33.

[0024] The cover part 23 is provided at both ends in the second direction of the grooves that constitute the plurality of pressure chambers 31 and the dummy chamber 32. The cover part 23 is made of, for example, a photosensitive resin. The cover part 23 is exposed and developed after the photosensitive resin is formed into a film, or is formed into a predetermined shape having a slit-shaped opening by being exposed, developed, and machined after the photosensitive resin is formed into a film. That is, on the inner surface on the pressure chamber side of the side walls 33 that constitute both side surfaces of the pressure chamber 31, protrusions protruding toward the pressure chamber side are formed. After applying the photosensitive resin to the inlets on both sides of the pressure chamber 31, the cover part 23 is formed into a predetermined shape that closes both ends of the grooves that constitute the dummy chamber 32 and a part of both ends of the grooves that constitute the pressure chamber 31 by a developing process in which the target part is cured by exposure and unnecessary unexposed resin is washed away with a developer.

[0025] The cover part 23 closes the end portion of the dummy chamber 32 in the second direction, and at the end portion of the pressure chamber 31 in the second direction, it has a plurality of protrusion parts 241 formed on both side surfaces in the first direction. The protrusion parts 241 are formed, for example, on both side surfaces of the pressure chamber 31 respectively.

[0026] The pair of protrusion parts 241 formed at the end of each pressure chamber 31 may be formed over the entire length in the third direction, which is the depth direction of the groove of the pressure chamber 31, or may be formed in a part in the third direction. For example, each of the pair of protrusion parts 241 is configured in a rectangular parallelepiped shape that is long in the third direction. The protrusion part 241 constitutes a throttle part 240 that increases the fluid resistance more than that in the pressure chamber by narrowing the opening of the communication port more than that in the pressure chamber.

[0027] That is, the groove forming the pressure chamber 31 is not completely covered by the protrusions 241, and a throttle port 242 that communicates the pressure chamber 31 with the first common chamber 271 and the second common chamber 272 is formed between the pair of protrusions 241. The throttle port 242 has a slit shape extending in the third direction that is the depth direction of the pressure chamber 31, and the opening width in the first direction thereof is configured to be smaller than the width in the first direction inside the pressure chamber 31, and thus is configured to be smaller than the flow path cross-sectional area of the pressure chamber 31. That is, a throttle portion 240 is formed in which the communication ports at both ends in the second direction are partially blocked by the protrusions 241 and the flow path resistance increases. The throttle portion 240 is formed by being exposed and developed after the formation of the photosensitive resin film, or by being exposed, developed, and machined after the formation of the photosensitive resin film. For example, the throttle portion 240 is configured in a predetermined shape by applying a photosensitive resin to the inlets on both sides of the pressure chamber 31, then curing the target portions constituting the protrusions 241 by exposure, and performing a developing process of washing away unnecessary unexposed resin with a developer. Alternatively, after applying a photosensitive resin to the pressure chamber 31 and curing the photosensitive resin at predetermined locations of the communication ports on both sides by exposure processing and developing processing, the throttle port 242 may be formed by machining such as dicing.

[0028] Note that if the fluid resistance of the throttle portion 240 is made too large, the replenishment of ink to the pressure chamber 31 after the ink droplet ejection will be delayed, which will inhibit the high speed operation. Also, the swelling of the meniscus varies depending on the ink viscosity, ejection volume, driving frequency, etc. Therefore, the shape of the protrusions 241 and the dimensions and positions of the throttle port 242 of the throttle portion 240 are set to have a flow path resistance corresponding to the ink replenishment conditions and the characteristics of the swelling of the meniscus.

[0029] The cover part 23 has a first part 231 formed in the gap between the side walls 33 and overlapping the wall surface of the side walls 33, and a second part 232 located outside the pressure chamber 31 than the side walls 33 in the second direction. That is, the throttle port 242 constituted by the protrusion 241 configured as a part of the cover part 23 integrally has a first part 2421 overlapping the side walls 33 and a second part 2422 extending outside the pressure chamber 31 in the second direction than the side walls 33. Here, the dimensions of the cover part 23, the protrusion 241, and the throttle port 242 in the second direction are configured such that the part overlapping the side walls 33 is longer than the part formed outside the side walls 33.

[0030] For example, as the first embodiment, the first part 231 is configured to be larger than the second part 232. That is, among the total thickness which is the dimension of the cover part 23 in the second direction, 50% or more overlaps the side walls 33. The dimension of the first part 2421 of the protrusion 241 in the second direction is 50% or more of the total length of the protrusion 241 in the second direction. That is, the length of the first part is longer than the second part. In other words, the dimension of the first part 2421 of the throttle port 242 in the second direction, which is the flow path length of the throttle port 242 constituted by the protrusion 241, is 50% or more of the total length of the throttle port 242 in the second direction. That is, the length of the first part 2421 is longer than the second part 2422.

[0031] FIG. 5 is an explanatory diagram showing the configuration of the throttle portion 240 according to the first embodiment, and FIG. 6 is an explanatory diagram showing the configuration of the throttle portion according to Comparative Example 1. FIG. 7 is a graph showing, for the first embodiment and Comparative Example 1, the dimensions of the width a [μm] at the outlet 2431 on the pressure chamber 31 side, which is inside the throttle port 242, with respect to the design value, and the dimensions of the width b [μm] at the inlet 2432 on the ink chamber 27 side, which is outside. In FIG. 7, for both the first embodiment and Comparative Example 1, the measured values of the width a [μm] and the width b [μm] in five different pressure chambers 31, the average value [μm] of each width, and the standard deviation are shown when the number of measurements n is 5. The first embodiment and Comparative Example 1 both show the measured values in five pressure chambers 31 when a slit that becomes the throttle port 242 is formed by dicing after the cover portion 23 is applied. In both the first embodiment and Comparative Example 1, the design value is set with the throttle length, that is, the total length of the throttle port 242 in the second direction being 500 μm, the throttle width, that is, the dimension of the slit that is the throttle port 242 in the first direction being 28 μm, and the width of the groove, that is, the dimension of the pressure chamber 31 in the first direction being 48 μm.

[0032] In the first embodiment, the lengths of both the first part and the second part are each 50% of the throttle length. In the first embodiment, the width dimension of the throttle port 242 inside the pressure chamber 31 was on average 27.98 μm, and the standard deviations of the width dimensions of the openings inside and outside the throttle portion 240 were about 0.13 and 0.16.

[0033] In Comparative Example 1, 40% of the throttle length was the first part and 60% was the second part. In the first embodiment, the width dimension of the throttle port 242 inside the pressure chamber 31 was on average 27.94 μm inside the pressure chamber and 25.36 μm on average at the opening outside the pressure chamber. Also, the standard deviations of the width dimensions of the openings inside and outside the throttle portion 240 were 0.11 and 0.33. As shown in FIG. 7, in the case of Comparative Example 1, the width of the slit as the throttle port 242 formed by machining varies greatly between the first part 2421 that overlaps the side wall 33 and the second part 2422 formed outside the side wall 33, and the variation in the width dimension of the outer inlet 2432 for each pressure chamber 31 becomes particularly large.

[0034] FIG. 8 is an explanatory diagram showing the configuration of the aperture portion 240 according to the second embodiment. In the second embodiment, the design values are set such that the aperture length, that is, the total length of the aperture 242 in the second direction is 500 μm, the aperture width, that is, the dimension of the slit-shaped aperture 242 in the first direction is 28 μm, and the groove width, that is, the dimension of the pressure chamber 31 in the first direction is 48 μm. For example, as the second embodiment, more than 80% of the total thickness, which is the dimension of the cover portion 23 in the second direction, is configured to overlap with the side wall 33. That is, in the aperture 242 formed by the protrusion 241, the dimension of the first portion 2421 is set to be 80% or more of the total length of the aperture 242 in the second direction. Further, in the second embodiment, based on the width dimension of the pressure chamber 31 in the first direction, the dimension of the first portion 2421 is set to be 80% or more of the total length of the aperture 242 in the second direction so that the thickness of the second portion in the second direction is the same as or less than the width dimension of the pressure chamber 31 in the first direction, or is approximately the same as or less than the width dimension of the pressure chamber 31 in the first direction.

[0035] FIG. 9 is an explanatory diagram showing the configuration of the throttle portion 240 according to the third embodiment. In the third embodiment, the design values are set such that the throttle length, that is, the total length of the throttle port 242 in the second direction is 500 μm, the throttle width, that is, the dimension of the slit constituting the throttle port 242 in the first direction is 28 μm, and the width of the groove, that is, the dimension of the pressure chamber 31 in the first direction is 48 μm. For example, as the third embodiment, more than 95% of the total thickness, which is the dimension of the cover portion 23 in the second direction, is the first portion 231 that overlaps with the side wall 33. That is, the throttle port 242 formed by the protrusion 241 has the dimension of the first portion 2421 being more than 95% of the total length of the throttle port 242 in the second direction. In this third embodiment, the dimension of the second portion 2422 in the second direction is set to be equal to or less than the wall thickness of the protrusion 241 formed by overlapping the side wall 33, that is, the thickness dimension of the protrusion 241 in the first direction in the first portion 2421. In the present embodiment, the wall thickness in the pressure chamber 31 is 10 μm, which is (groove width 48 μm - slit width 28 μm) / 2. And the length of the first portion 2421 is 490 μm, that is, 98% of the total length. In this embodiment, based on this wall thickness, the thickness of the second portion in the second direction is set to be the same as or less than the wall thickness in the pressure chamber 31 of the first portion, or equal to or less than the wall thickness. As an example, the thickness of the second portion in the second direction is set to be equal to or less than the thickness of the thinnest portion among the wall thicknesses of the bottom surface portion and the side surface portion in the pressure chamber 31 of the first portion, based on the thinnest portion. In the present embodiment, as an example, the dimension of the first portion 2421 is set to be more than 95% of the total length of the throttle port 242 in the second direction.

[0036] FIG. 10 is an explanatory diagram showing the configuration of the throttle portion 240 according to the fourth embodiment. In the fourth embodiment, the design values are set such that the throttle length, that is, the total length of the throttle port 242 in the second direction is 500 μm, the throttle width, that is, the dimension of the slit constituting the throttle port 242 in the first direction is 28 μm, and the width of the groove, that is, the dimension of the pressure chamber 31 in the first direction is 48 μm. In the fourth embodiment, the entire cover portion 23 and the protrusion 241 are formed by overlapping between the side walls 33 or on the inner wall of the side wall 33. That is, it is a configuration without a second portion. In this embodiment, 100% of the total thickness of the cover portion 23 becomes the first portion 231.

[0037] 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.

[0038] The plurality of nozzles 28 are provided in the same number as the pressure chambers 31 and are respectively arranged to face the pressure chambers 31. The nozzles 28 are arranged in a plurality along the first direction and are arranged in two rows corresponding to the pair of actuator members 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 in which the diameter is reduced toward the central portion or the tip portion. The nozzles 28 are arranged to face the middle portion in the extending direction of the pressure chambers 31 formed in the pair of actuator members 22 and communicate with the pressure chambers 31 respectively. The nozzles 28 are arranged one by one at the longitudinal center portion of each pressure chamber 31.

[0039] The frame 13 is formed in a rectangular frame shape of, 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.

[0040] 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.

[0041] The circuit board 17 is a film carrier package (FCP). The circuit board 17 has a plurality of wirings formed thereon, and includes a resin film 51 having flexibility and an IC 52 connected to the plurality of wirings of the film 51. The IC 52 is electrically connected to the electrode layer 34 via the wirings of the film 51 and the pattern wiring 211.

[0042] Inside the inkjet head 10 configured as described above, an ink chamber 27 surrounded by the actuator base 11, the nozzle plate 12, and the frame 13 is formed. 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 by two actuator members 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.

[0043] 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, by a signal input from the control unit of the inkjet printer, the drive IC 52 applies a drive voltage to the electrode layer 34 of the pressure chamber 31 via the wiring of the film 51, thereby generating a potential difference between the electrode layer 34 of the pressure chamber 31 and the electrode layer 34 of the dummy chamber 32, and selectively deforming the side wall 33 in the shear mode. By deforming the side wall 33 formed between the pressure chamber 31 and the dummy chamber 32 in response to a drive signal, the volume of the pressure chamber 31 is changed.

[0044] When the side wall 33 deforms in the shear mode, the volume of the pressure chamber 31 provided with the electrode layer 34 increases and the pressure decreases. As a result, the ink in the ink chamber 27 flows into the pressure chamber 31.

[0045] With the volume of the pressure chamber 31 increased, the IC 52 applies a drive voltage with an inverse potential to the electrode layer 34 of the pressure chamber 31. As a result, the side wall 33 deforms in the shear mode, the volume of the pressure chamber 31 provided with the electrode layer 34 decreases, and the pressure increases. Thereby, the ink in the pressure chamber 31 is pressurized and ejected from the nozzle 28.

[0046] A method for manufacturing an 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 member 22 having an outer shape of a predetermined 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.

[0047] Subsequently, an electrode layer 34 and a pattern wiring 211 are formed on the inner surface of the grooves constituting the pressure chamber 31 and the dummy chamber 32 and the surface of the substrate 21. As described above, the electrode layer 34 and the pattern wiring 211 are formed at predetermined positions on the surface of the actuator base 11. Subsequently, a cover portion 23 is formed of a photosensitive resin. For example, the cover portion 23 includes a filling process of filling a photosensitive resin material into communication ports that are the entrances and exits on both sides of the grooves constituting the dummy chamber 32 and the pressure chamber 31 and closing the communication ports at both ends with the photosensitive resin, and a molding process of molding the photosensitive resin into a predetermined shape. As an example, after filling a photosensitive resin material into the communication ports on both sides of the grooves constituting the dummy chamber 32 and the pressure chamber 31, an exposure mask having an exposure pattern in which a portion to form an aperture 242 is uncured is overlaid and exposed, so that portions other than the uncured target portion to become the aperture 242 are cured, and a developing process of washing away the uncured portion with a developer is performed to open the aperture 242 having a predetermined shape. As described above, the photosensitive resin material is molded into a predetermined shape, and a throttle portion 240 is formed. That is, a cover portion 23 having a pair of protrusions 241 with an aperture 242 formed therebetween is formed.

[0048] Also, as another example, for instance, when sufficient resolution cannot be obtained in forming a tapered pattern of a photosensitive resin by exposure depending on conditions, the tapered opening 242 may be formed by machining to form the protruding portion 241. As a filling process Act1, a photosensitive resin material is applied and filled at both ends of the dummy chamber 32 and the pressure chamber 31, and the filled photosensitive resin material is cured by exposure and development processes to block the communication ports of the dummy chamber 32 and the pressure chamber 31 with walls of the photosensitive resin. Then, as a molding process, the tapered opening 242 is formed by machining using a dicing saw having a desired width. Thus, the cover portion 23 having the protruding portion 241 of a predetermined shape is formed.

[0049] Furthermore, 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 an adhesive sheet of a thermoplastic resin.

[0050] Then, the assembled frame 13, the top 222 of the side wall 33 of the actuator member 22, and the opposing surfaces facing the nozzle plate 12 of the protruding portion 241 are polished so as to be on the same plane. Then, the nozzle plate 12 is adhered and attached to the polished top 222 of the side wall 33, the frame 13, and the opposing surfaces of the protruding portion 241. At this time, positioning is performed so that the nozzle 28 faces the pressure chamber 31. Further, by connecting the drive IC chip 52 and the circuit board 17 to the pattern wiring 211 formed on the main surface of the substrate 21 as shown in FIG. 1 via a flexible printed circuit board, the inkjet head 10 is completed.

[0051] Hereinafter, an example of an inkjet printer 100 including the inkjet head 10 will be described with reference to FIG. 21. 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.

[0052] The inkjet printer 100 is a liquid ejection device that performs an image forming process on 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.

[0053] The housing 111 forms 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.

[0054] 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.

[0055] 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.

[0056] The image forming unit 113 includes a support unit 117 that supports the sheet of paper P, and a plurality of head units 130 disposed opposite the upper side of the support unit 117.

[0057] 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.

[0058] During image formation, the support unit 117 supports the sheet of paper P on the holding surface, which is the upper surface of the conveyance belt 118, and conveys the sheet of paper P to the downstream side by sending the conveyance belt 118 at a predetermined timing by the rotation of the belt rollers 120.

[0059] The head unit 130 includes a plurality (4 colors) of inkjet heads 10, ink tanks 132 as liquid tanks respectively mounted on each inkjet head 10, a connection flow path 133 connecting the inkjet head 10 and the ink tank 132, and a circulation pump 134 which is a circulation section. The head unit 130 is a circulation type head unit that constantly circulates liquid in the ink tank 132, the pressure chamber 31, the dummy chamber 32, and the ink chamber 27 formed inside the inkjet head 10.

[0060] In the present embodiment, it includes four-color inkjet heads 10 of cyan, magenta, yellow, and black, and ink tanks 132 that store the inks of these respective colors. The ink tank 132 is connected to the inkjet head 10 by a connection flow path 133. The connection flow path 133 includes a supply flow path connected to the supply port of the inkjet head 10 and a recovery flow path connected to the discharge port of the inkjet head 10.

[0061] Also, 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, so as to form a meniscus of a predetermined shape with the ink supplied to each nozzle 28 of the inkjet head 10.

[0062] The circulation pump 134 is a liquid feed 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 liquid in the circulation flow path including the inkjet head 10 and the ink tank 132.

[0063] The conveying device 115 conveys the paper P along a conveyance path A that extends from the medium supply unit 112, passes through the image forming unit 113, and reaches the medium discharge unit 114. The conveying device 115 includes a plurality of pairs of guide plates 121 arranged along the conveyance path A and a plurality of conveying rollers 122.

[0064] Each of the plurality of pairs of guide plates 121 includes a pair of plate members that are arranged to face each other with the conveyed paper P therebetween, and guides the paper P along the conveyance path A.

[0065] The conveying roller 122 is driven to rotate under the control of the control unit 116, and thereby sends the paper P downstream along the conveyance path A. Sensors for detecting the conveyance state of the paper are arranged at various positions along the conveyance path A.

[0066] The control unit 116 includes a control circuit such as a CPU that is a controller, a ROM (Read Only Memory) that stores various programs and the like, a RAM (Random Access Memory) that temporarily stores various variable data, image data, and the like, and an interface unit that inputs data from the outside and outputs data to the outside.

[0067] In the inkjet printer 100 configured as described above, when the control unit 116 detects a print instruction by the user's operation of the operation input unit at the interface, for example, it drives the conveyance device 115 to convey the paper P, and outputs a print signal to the head unit 130 at a predetermined timing, thereby driving the inkjet head 10. As a discharge operation, the inkjet head 10 sends a drive signal to the IC by an image signal corresponding to the image data, applies a drive voltage to the electrode layer 34 of the pressure chamber 31 via a wiring, selectively drives the side wall 33 of the actuator member 22, discharges ink from the nozzle 28, and forms an image on the paper P held on the conveyance belt 118. Further, as a liquid discharge operation, the control unit 116 drives the 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 supply section of the manifold 18 through the supply hole 25 to the first common chamber 271 of the ink chamber 27 when the circulation pump 134 is driven. This ink is supplied to a plurality of pressure chambers 31 of the pair of actuator members 22 and a plurality of dummy chambers 32. The ink flows into the second common chamber 272 of the ink chamber 27 through the pressure chamber 31 and the dummy chamber 32. This ink is discharged from the discharge hole 26 to the ink tank 132 through the ink discharge section of the manifold 18.

[0068] According to the above-described embodiment, it is possible to provide a liquid discharge head and a method for manufacturing the liquid discharge head that can ensure stable discharge characteristics. That is, the inkjet head 10 according to the above embodiment includes the cover portion 23 in the pressure chamber 31, so that the inlet and outlet of the pressure chamber 31 have a larger flow path resistance than the inside of the pressure chamber 31, the first common chamber 271, and the second common chamber 272. As a specific example, the opening that opens into the first common chamber 271 or the second common chamber 272, which is the common chamber of the pressure chamber 31, is smaller than the flow path cross-sectional area of the pressure chamber 31. For this reason, the swelling of the meniscus when liquid is discharged in the inkjet head 10 becomes smaller. Therefore, the return of the meniscus is accelerated, the influence on the next shot can be reduced, and the discharge stability can be improved.

[0069] FIG. 12 shows Test Example 1 of the inkjet head 110 including a throttle (throttle portion 240) and Test Example 2 of the inkjet head 1010 not including a throttle. FIG. 13 shows the frequency characteristics of the inkjet head 110 having a throttle according to Test Example 1, and FIG. 14 shows the frequency characteristics of the inkjet head 1010 not including a throttle as Comparative Example 2. In FIGS. 13 and 14, the relationships between the ejection speed of the nozzles and the frequency are shown for the cases of 1 drop and 3 drops, respectively.

[0070] The inkjet head 110 according to Test Example 1 is a side shooter type in which both sides in the second direction, which is the extending direction of the pressure chamber 31, communicate with the common chamber, and the nozzle 28 opens at an intermediate portion in the extending direction of the pressure chamber 31.

[0071] As shown in FIG. 14, in the inkjet head 1010 according to Test Example 2, the ejection speed is flat in the low frequency region, but the ejection speed tends to decrease as the frequency increases, and there is a difference in the ejection speed between the low frequency region and the high frequency region. In the case of 1 drop of the inkjet head 1010 according to Test Example 2, the ejection speed is flat up to 25 kHz, but the ejection speed tends to decrease as the frequency increases above 25 kHz. Also, in the case of 3 drops of the inkjet head 1010 according to Test Example 2, the ejection speed is flat up to 15 kHz, but the ejection speed tends to decrease as the frequency increases above 15 kHz. Therefore, a deviation occurs in the landing position depending on the printed pattern. When the difference in the ejection speed is large in this way, it takes time for the meniscus swelling to subside, causing a deterioration in the printing quality, so it cannot be driven at high speed.

[0072] On the other hand, as shown in FIG. 13, in the inkjet head 110 having a throttle portion, the ejection speed tends to be flat for both 1 drop and 3 drops. This is because the fluid resistance between the nozzles from the common liquid becomes large and the swelling of the meniscus becomes small.

[0073] Figure 15 shows the simulation results of the meniscus return for Test Example 1 with a throttle provided in the pressure chamber and Test Example 2 without a throttle. According to Figure 15, in the case of low frequency, for the meniscus state of the nozzle, there is sufficient time from when an ink droplet is ejected until the next shot is ejected, and ejection can be performed in a stable state after waiting for the meniscus to return regardless of the presence or absence of a throttle. On the other hand, in the case of high frequency, since the time from when a dot (ink droplet) is ejected until the next shot is ejected is short, the ejection of the next shot starts before the meniscus returns. Therefore, in the case of the inkjet head 1010 without a throttle, after ejection, the swelling of the meniscus becomes large, the meniscus cannot return by the time of the next shot, and the ejection speed decreases. In contrast, when a throttle is provided, the swelling of the meniscus becomes small, so the return of the meniscus is accelerated and the influence on the next shot can be reduced. Thus, from these simulation results, it can be said that providing a throttle between the pressure chamber 31 and the common chamber leads to an improvement in the ejection stability of the inkjet head 110.

[0074] Figure 16 is an explanatory diagram of a side shooter type inkjet head 110 as Test Example 1 and a share mode shared wall type end shooter type inkjet head 2010 as Test Example 3 in which an ink inlet / outlet is formed at one end and nozzles are formed at the other end.

[0075] Figures 17 to 20 are diagrams comparing the simulation characteristics when a throttle is provided in the end shooter type inkjet head 2010 as Test Example 3 and the inkjet head 110 of the side shooter type Test Example 1, respectively. Figure 17 shows the drive waveform, Figure 18 shows the nozzle flow velocity vibration, Figure 19 shows the ejection volume, and Figure 20 shows the meniscus return characteristics.

[0076] In addition, the inkjet head 2010 according to Test Example 3 is an end shooter type in which one end side in the second direction, which is the extending direction of the pressure chamber 31, communicates with the common chamber, the other end is closed, and nozzles are opened at the end of the flow path. That is, the inkjet head 2010 constitutes a flow path that flows from one side in the second direction toward the nozzle 28.

[0077] As the end shooter type inkjet head 2010 supplied from one side in Test Example 3 and the inkjet head 110 of the side shooter type with two-sided supply in Test Example 1 have the same ejection volume, nozzle flow velocity vibration, and meniscus return characteristics, the drive voltage of the two-sided supply side shooter type configuration is the lowest. Therefore, it can be said that two-sided supply has a high superiority over one-sided supply from the perspective of drive efficiency. That is, the so-called side shooter type inkjet head 110, which has a nozzle at the center of the pressure chamber and ink inlets and outlets at both ends, has better ejection efficiency than the end shooter type inkjet head 2010.

[0078] In general, in a shared mode shared wall type inkjet head, for example, since the pressure chamber is composed of fine grooves formed in the piezoelectric body with a diamond cutter, it is difficult to reduce the cross-section of a part of the pressure chamber. However, according to the above embodiment, by making the first part 2421 sandwiched between the side walls 33 in the throttle port 242 be 50% or more, it is easy to design the shape of the throttle part 240 with high precision. Also, by reducing the second part 2422 protruding from the side wall 33 to the outside of the pressure chamber 31, dimensional variations can be suppressed, and the flow path resistance of the throttle port 242 can be stabilized. Further, in the above embodiment, since the side surface part 221 of the actuator member 22 constitutes an inclined surface, there are few restrictions on the exposure direction, and exposure and development processes become easy. Also, by using mechanical processing in combination, finer patterning can be realized with high precision.

[0079] Also, in the second embodiment, by making the first part 2421 sandwiched between the side walls 33 in the throttle port 242 be 80% or more and making the dimension of the second part 2422 protruding to the outside of the pressure chamber 31 be equal to or less than the width dimension of the pressure chamber 31, generation of bubbles larger than inside the pressure chamber 31 can be suppressed. Therefore, the dimension of the throttle port 242 can be set with high precision, and the flow path resistance of the throttle port 242 can be stabilized.

[0080] Also, in the third embodiment, in the throttle port 242, the first portion 2421 sandwiched between the side walls 33 is set to 90% or more, and the dimension of the second portion 2422 protruding outside the pressure chamber 31 is set to be equal to or less than the wall thickness inside the pressure chamber 31, whereby the influence of swelling or the like can be suppressed. That is, even if swelling occurs depending on the type of ink, if the thickness is equal to or less than the wall thickness inside the pressure chamber, swelling can be suppressed less than in the case where the thickness of the second portion is large as shown in FIG. 11 as Comparative Example 2. Therefore, the dimensions of the throttle port 242 can be set with high precision, and the flow path resistance of the throttle port 242 can be stabilized.

[0081] Also, in the inkjet head 10 according to the above embodiment, since a throttle is partially formed at the communication port serving as the inlet and outlet of the pressure chamber 31, it is easier to secure the volume of the pressure chamber 31 than to reduce the width of the entire pressure chamber 31. Therefore, compared with a configuration in which the entire pressure chamber is narrowed, there are fewer restrictions on the size of the nozzles and droplets, and it is easy to maintain the ejection performance.

[0082] Note that the present invention is not limited to the above embodiment as it is, and at the implementation stage, the components can be modified and embodied without departing from the gist thereof.

[0083] In the above embodiment, as an example, the first common chamber 271 is arranged on one side of the pressure chamber 31, and the second common chamber 272 is arranged on the other side, and an example in which the fluid flows in from one side of the pressure chamber and out from the other side is shown, but the present invention is not limited thereto. For example, the common chambers on both sides of the pressure chamber 31 may be on the supply side, and a configuration in which the fluid flows in from both sides may be used. That is, a configuration in which the fluid flows in from both sides of the pressure chamber 31 and flows out from the nozzle 28 arranged at the center of the pressure chamber 31 may be used. Even in this case, by providing throttles at the inlet portions on both sides of the pressure chamber 31, the fluid resistance increases, and the ejection efficiency can be improved.

[0084] In addition, in the above-described embodiment, the throttle portion 240 that increases the flow path resistance has a configuration having a pair of protrusions 241 formed on the wall surfaces of the side walls 33 on both sides of the pressure chamber 31. However, the shape of the throttle portion 240 is not limited to this. For example, although the throttle opening 242 has a slit shape extending in the third direction that is the depth direction of the pressure chamber, it may extend in other directions, or may have other shapes including circular or oval shapes. Further, the shape, position, and size of the throttle portions 240 provided on both sides can be set according to the flow path resistance, and they may be configured under the same conditions on both sides, or the throttle portions 240 on one side and the other side may be configured under different conditions.

[0085] In the above-described embodiment, an example in which the actuator member 22 having a plurality of grooves is arranged on the main surface portion of the substrate 21 is shown. However, the present invention is not limited to this. For example, the end face of the substrate 21 may have a configuration including an actuator. Further, the number of nozzle rows is not limited to the above-described embodiment, and may be configured to include one row or three or more rows.

[0086] In addition, in the above-described embodiment, the actuator base 11 including the laminated piezoelectric body made of the piezoelectric member is illustrated on the substrate 21. However, the present invention is not limited to this. For example, the actuator member 22 may be formed only of the piezoelectric member without using the substrate. Further, instead of using two piezoelectric members, a single piezoelectric member may be used. Further, the dummy chamber 32 may communicate with the first common chamber 271 or the second common chamber 272 that is a common chamber. Further, the supply side and the discharge side may be reversed, or may be configured to be switchable.

[0087] In the above embodiment, as an example, one side of the pressure chamber 31 is the supply side, and the other side is the discharge side, and a circulation type inkjet head in which fluid flows in from one side of the pressure chamber and out from the other side is exemplified, but it 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 side, and the configuration may be such that fluid flows in from both sides. That is, a configuration may be adopted 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. Even in this case, by providing the throttle portion 240 at the communication ports serving as the inlets on both sides of the pressure chamber 31, the fluid resistance increases and the discharge efficiency can be improved. For example, a non-circulation configuration may be adopted by not providing a flow path on the discharge side or by closing the flow path on the discharge side. For example, a supply hole 25 may be provided instead of the discharge hole 26, or the flow path on the discharge side may be opened only during ink replenishment or maintenance and closed during printing, and a non-circulation configuration may be adopted.

[0088] For example, the liquid to be discharged is not limited to the ink for printing, and for example, an apparatus that discharges a liquid containing conductive particles for forming a wiring pattern of a printed wiring board may be used.

[0089] Further, in the above embodiment, an example in which the inkjet head is used in a liquid discharge apparatus such as an inkjet printer is shown, but it is not limited thereto. For example, it can also be used in a 3D printer, an industrial manufacturing machine, and medical applications, and can be made smaller, lighter, and less costly.

[0090] According to at least one of the embodiments described above, it is possible to provide a liquid discharge head capable of ensuring stable discharge characteristics and a method for manufacturing the liquid discharge head.

[0091] In addition, although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and 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) An actuator having a plurality of pressure chambers communicating with a plurality of nozzles for discharging a liquid, a plurality of grooves forming a plurality of dummy chambers arranged between the plurality of pressure chambers, and side walls formed between the plurality of grooves and changing the volume of the pressure chamber in response to a drive signal. A common chamber communicating with both ends of the plurality of pressure chambers A cover portion having a throttle port that blocks a part of a communication port through which the pressure chamber communicates with the common chamber at both ends of the pressure chamber, communicates with the pressure chamber, and has a greater fluid resistance than the inside of the pressure chamber. The cover portion integrally has a first portion formed to overlap the side wall and disposed in the groove, and a second portion formed outside the groove. The dimension of the first portion in the extending direction of the pressure chamber is 50% or more of the dimension of the cover portion in the extending direction of the pressure chamber. A side shooter type liquid ejection head. (2) The cover portion is made of a photosensitive resin. The liquid ejection head according to (1), wherein the dimension of the first portion in the extending direction of the pressure chamber is 80% or more of the dimension of the cover portion in the extending direction. (3) The liquid ejection head according to (1), wherein the dimension of the first portion in the extending direction of the pressure chamber is 95% or more of the dimension of the cover portion in the extending direction. (4) The plurality of nozzles and the plurality of pressure chambers are arranged side by side in a first direction. Each of the pressure chambers extends in a second direction intersecting the first direction. The nozzles are arranged at positions corresponding to the middle portions of the pressure chambers in the second direction. The ejection direction of the nozzles intersects both the first direction and the second direction. The liquid ejection head according to any one of (1) to (3), wherein the dimension of the throttle port in the first direction is configured to be smaller than the dimension of the pressure chamber in the first direction. (5) The liquid ejection head according to any one of (1) to (4), wherein the dimension of the second portion in the extending direction of the pressure chamber is equal to or less than the width dimension of the pressure chamber intersecting the extending direction.

Description of Reference Numerals

[0092] 10... Inkjet head, 11... Actuator base, 12... Nozzle plate, 13... Frame, 17... Circuit board, 18... Manifold, 21... Substrate, 22... Actuator member, 23... Cover part, 231... First part, 232... Second part, 25... Supply hole, 26... Discharge hole, 27... Ink chamber, 31... Pressure chamber, 32... Dummy chamber, 33... Side wall, 34... Electrode layer, 51... Film, 52... Driving IC chip, 100... Inkjet printer, 111... Housing, 112... Medium supply part, 113... Image forming part, 114... Medium discharge part, 115... Conveyor, 116... Control part, 117... Support part, 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, 222... Top part, 240... Throttle part, 241... Protrusion part, 242... Throttle opening, 2421... First part, 2422... Second part, 271... First common chamber, 27... Ink chamber, 272... Second common chamber.

Claims

1. A plurality of grooves forming a plurality of pressure chambers communicating with a plurality of nozzles for discharging a liquid, and a plurality of dummy chambers arranged between the plurality of pressure chambers, and formed between the plurality of grooves, and actuated according to a drive signal An actuator having side walls that change the volume of the pressure chamber; A common chamber communicating with both ends of the plurality of pressure chambers; A cover portion having a throttle port that closes a part of a communication port through which the pressure chamber communicates with the common chamber at both ends of the pressure chamber, communicates with the pressure chamber, and has a greater fluid resistance than the inside of the pressure chamber; The cover portion integrally has a first portion formed to overlap the side wall and disposed in the groove, and a second portion formed outside the groove; In the entire depth direction of the pressure chamber, the dimension of the first portion in the extending direction of the pressure chamber is 50% or more of the dimension of the cover portion in the extending direction of the pressure chamber; A side shooter type liquid discharge head.

2. The cover portion is made of a photosensitive resin, In the entire depth direction of the pressure chamber, the dimension of the first portion in the extending direction of the pressure chamber is 80% or more of the dimension of the cover portion in the extending direction. The liquid discharge head according to claim 1.

3. In the entire depth direction of the pressure chamber, the dimension of the first portion in the extending direction of the pressure chamber is 95% or more of the dimension of the cover portion in the extending direction. The liquid discharge head according to claim 1.

4. The plurality of nozzles and the plurality of pressure chambers are arranged side by side in a first direction, Each of the pressure chambers extends in a second direction intersecting the first direction, The nozzles are arranged at positions corresponding to intermediate portions of the pressure chambers in the second direction, The discharge direction of the nozzles intersects both the first direction and the second direction, and The liquid ejection head according to any one of claims 1 to 3, wherein a dimension of the aperture in the first direction is configured to be smaller than a dimension of the pressure chamber in the first direction.

5. The liquid ejection head according to any one of claims 1 to 4, wherein a dimension of the pressure chamber in the extending direction of the second portion is equal to or smaller than a width dimension of the pressure chamber intersecting the extending direction.

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