Liquid dispensing head

Abstract

To provide a liquid discharge head capable of securing stable discharge characteristics.SOLUTION: A liquid discharge head includes an actuator part, and a narrowed part. The actuator part has a plurality of pressure chambers. The narrowed part includes a narrowed wall which is provided on a communication port between a common chamber communicating with the pressure chamber with the pressure chamber, and has a guide surface inclined or curved on at least an inside surface of the pressure chamber.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 speeding up and increasing the amount of liquid droplets have become problems. For example, a share mode shared wall type inkjet head becomes high power and is suitable for discharging high-viscosity ink and large liquid droplets. In a share mode shared wall type inkjet head, the same drive column is shared by two pressure chambers, and so-called three-cycle driving is generally used in which one-third 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 inlets and outlets are blocked every other one, the grooves whose inlets and outlets are not blocked are used as pressure chambers, and the blocked grooves are used as air chambers for independent driving.

[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 meniscus swells due to overshoot at the nozzle. The smaller the fluid resistance of the flow path from the common liquid chamber to the nozzle, the larger the overshoot becomes, and if this overshoot does not subside, the meniscus cannot eject in a stable state. Therefore, in order to increase the speed in 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 that this invention aims to solve is to provide a liquid dispensing head that can ensure stable dispensing characteristics. [Means for solving the problem]

[0006] A liquid dispensing head according to one embodiment is The device has multiple element walls made of piezoelectric material, grooves forming pressure chambers and air chambers between the multiple element walls, and the multiple pressure chambers and multiple air chambers are arranged alternately in the direction in which the multiple element walls are aligned, and is an independently driven type Actuator section, multiple A throttling section is provided at the communication opening between a common chamber communicating with the pressure chamber and the pressure chamber, and comprises a throttling wall having a guide surface that is inclined or curved on at least the inner surface of the pressure chamber. The device is a side-shooter type in which both sides of the extension direction of the plurality of pressure chambers communicate with a common chamber, and liquid is supplied to the plurality of pressure chambers from the common chamber on both sides in the extension direction, and the constriction wall is made of a photosensitive resin, and the constriction wall is a projection provided on a pair of element walls that constitute the pressure chamber, which are arranged on one side and the other side in the direction in which the plurality of pressure chambers are arranged, respectively, at the communication openings on both sides in the extension direction of the pressure chamber. [Brief explanation of the drawing]

[0007] [Figure 1] A perspective view showing an inkjet head according to an embodiment. [Figure 2] An exploded perspective view showing a partial configuration of an inkjet head according to an embodiment. [Figure 3] A perspective view showing a magnified view of a portion of the components of the inkjet head. [Figure 4] A cross-sectional view showing a magnified view of a part of the inkjet head's components. [Figure 5] A cross-sectional view showing a magnified view of a part of the inkjet head's components. [Figure 6] An explanatory diagram showing some of the components and fluid flow of the inkjet head. [Figure 7] Diagram illustrating the inkjet heads related to Test Example 1 and Test Example 2. [Figure 8] A graph showing the ejection speed of the inkjet head related to Test Example 1. [Figure 9] A graph showing the ejection speed of the inkjet head in Test Example 2. [Figure 10] Graphs showing the meniscus return characteristics of the inkjet heads in Test Example 1 and Test Example 2. [Figure 11]Explanatory drawing of the inkjet head of the end shooter according to Test Example 1 and Test Example 3. [Figure 12] Graph showing the drive waveforms of the inkjet head according to Test Example 1 and Test Example 3. [Figure 13] Graph showing the nozzle flow rate vibration of the inkjet head according to Test Example 1 and Test Example 3. [Figure 14] Graph showing the discharge volume of the inkjet head according to Test Example 1 and Test Example 3. [Figure 15] Graph showing the meniscus return characteristics of the inkjet head according to Test Example 1 and Test Example 3. [Figure 16] Schematic diagram showing the inkjet printer according to the embodiment. [Figure 17] Explanatory drawing showing a part of the configuration of the inkjet head and the flow of fluid according to another embodiment. [Figure 18] Explanatory drawing showing a part of the configuration of the inkjet head and the flow of fluid according to another embodiment. [Figure 19] Explanatory drawing showing a part of the configuration of the inkjet head and the flow of fluid according to another embodiment. [Figure 20] Explanatory drawing showing a part of the configuration of the inkjet head and the flow of fluid according to another embodiment. [Figure 21] Explanatory drawing showing a part of the configuration of the inkjet head and the flow of fluid according to another embodiment. [Figure 22] Explanatory drawing showing a part of the configuration of the inkjet head and the flow of fluid according to another embodiment. [Figure 23] Explanatory drawing showing a part of the configuration of the inkjet head and the flow of fluid according to another embodiment. [Figure 24] Explanatory drawing showing a part of the configuration of the inkjet head and the flow of fluid according to another embodiment. [Figure 25] Explanatory drawing showing a part of the configuration of the inkjet head and the flow of fluid according to another embodiment.

Mode for Carrying Out the Invention

[0008] The configuration of an inkjet head 10, which is a liquid ejection head according to the first embodiment, will be described below with reference to FIGS. 1 to 6. 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 and 5 are cross-sectional views showing an enlarged configuration of a part of the inkjet head. FIG. 6 is an explanatory view showing a part of the configuration of the inkjet head and the flow of fluid. In the figure, X, Y, and Z respectively indicate the first direction, the second direction, and the third direction that are perpendicular to each other. In the present 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 to this.

[0009] As shown in FIGS. 1 to 6, the inkjet head 10 is a share mode share 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. In the present embodiment, the inkjet head 10 is a so-called side shooter type inkjet head.

[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 as 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 for controlling 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 Figures 2 to 5, the actuator base 11 comprises a substrate 21, a pair of actuator parts 22, and a throttling part 240.

[0013] The substrate 21 is formed in the shape of a rectangular plate from a ceramic such as alumina. The substrate 21 has a flat mounting surface. A pair of actuator parts 22 are bonded to the mounting surface of the substrate. Multiple supply holes 25 and discharge holes 26 are formed in the substrate 21.

[0014] As shown in Figures 2 and 3, pattern wiring 211 is formed on the substrate 21 of the actuator base 11. The pattern wiring 211 is formed, for example, from a nickel thin film. The pattern wiring 211 has common patterns and individual patterns and is configured in a predetermined pattern shape that is connected to the electrode layer 34 formed on the actuator part 22.

[0015] The supply holes 25 are located in the center of the substrate 21, between a pair of actuator units 22, and are arranged along the longitudinal direction of the actuator units 22. The supply holes 25 communicate with the ink supply unit of the manifold 18. The supply holes 25 are connected to the ink tank via the ink supply unit. The supply holes 25 supply ink from the ink tank to the ink chamber 27.

[0016] The discharge holes 26 are arranged in two rows, flanking the supply holes 25 and the pair of actuator units 22. The discharge holes 26 communicate with the ink discharge section of the manifold 18. The discharge holes 26 are connected to the ink tank via the ink discharge section. The discharge holes 26 discharge the ink from the ink chamber 27 to the ink tank.

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

[0018] The actuator section 22 has a width in the short direction that gradually increases from the top 222 side toward the substrate side. The cross-sectional shape of the actuator section 22 along the direction perpendicular to the longitudinal direction (short direction) is formed as a trapezoid. The side portion 221 of the actuator section 22 has inclined surfaces that are inclined with respect to the second and third directions. The top 222 of the actuator section 22 is bonded to the nozzle plate 12. The actuator section 22 comprises a plurality of pressure chambers 31 and a plurality of air chambers 32. The actuator section 22 has a plurality of element walls 33 (wall portions), and grooves that constitute the pressure chambers 31 and air chambers 32 are located between the element walls 33. In other words, the element walls 33 are formed as driving elements between the grooves that form the pressure chambers 31 and air chambers 32.

[0019] As shown in Figures 1 to 5, the bottom surface of the groove and the main surface of the substrate 21 are connected by an inclined side surface 221. Multiple pressure chambers 31 and multiple air chambers 32 are arranged alternately. The pressure chambers 31 and air chambers 32 extend in directions intersecting the longitudinal direction of the actuator section 22, and multiple chambers are arranged in parallel in the longitudinal direction (X direction) of the actuator section 22. That is, the direction in which the multiple pressure chambers 31 and air chambers 32 are arranged is along the X direction. In this embodiment, for example, the width dimension of the groove 14 in the X direction is configured to be constant in the depth direction along the Z direction, and the cross section perpendicular to the Y direction, which is the extension direction, is configured to be rectangular.

[0020] The shape of the pressure chamber 31 and the shape of the air chamber 32 may be different. The element wall 33 is formed between the pressure chamber 31 and the air chamber 32 and changes the volume of the pressure chamber 31 by deforming in response to the drive signal.

[0021] Electrode layers 34 are provided on the inner wall surfaces of the pressure chamber 31 and air chamber 32 of the actuator base 11, respectively. The electrode layers 34 are formed of a conductive film, such as a nickel thin film. The electrode layers 34 extend from the inner surface of the groove onto the substrate 21 and are connected to the pattern wiring 211. For example, the electrode layers 34 are formed on at least the side surfaces of the element wall 33, i.e., on the side wall surfaces of the grooves constituting the pressure chamber 31. The electrode layers 34 may also be formed on the side and bottom surfaces of the pressure chamber 31, for example.

[0022] Multiple pressure chambers 31 communicate with multiple nozzles 28 of a nozzle plate 12 joined to the top portion 222 of the element wall 33. Both ends of the pressure chamber 31 in the second direction communicate with the ink chamber 27. That is, one end opens into the first common chamber 271 of the ink chamber 27, and the other end opens into the second common chamber 272 of the ink chamber 27. Therefore, ink flows in from one end of the pressure chamber 31 and flows out from the other end. A throttling portion 240 is formed at the communication opening of the pressure chamber 31 with the ink chamber 27, having a throttling opening 242 configured to have a greater fluid resistance than the inside of the pressure chamber 31. As an example, in this embodiment, throttling portions 240 are formed at the communication openings at both ends of the pressure chamber 31 in the extending direction.

[0023] As shown in Figures 4 to 6, the aperture portion 240 is configured to narrow the opening of the pressure chamber 31 that communicates with the ink chamber 27 in the X direction. As an example, the aperture portion 240 has a projection 241 that protrudes from the element wall 33 into the groove at the second end of the pressure chamber 31. The projection 241 is made of photosensitive resin.

[0024] In this embodiment, a pair of element walls 33 that constitute both sides of the pressure chamber 31 in the X direction, i.e., the element walls 33 on both sides in the X direction, each have projections 241 made of photosensitive resin.

[0025] For example, the projection 241 may be formed along its entire length in the third direction, which is the depth direction of the groove of the pressure chamber 31, or it may be formed in only a part of the third direction. Also, the projection 241 may have a photosensitive resin formed on the bottom surface of the groove in addition to the side surface of the groove. That is, the projections 241 on both sides may be continuous at the bottom of the groove.

[0026] The inner surface of the pressure chamber 31 in the Y direction of the projection 241 constitutes a guide surface 2411 having a chamfered or R-shaped form. The surface direction or tangential direction of the guide surface 2411 is inclined at less than 90 degrees with respect to the surface of the element wall 33. Specifically, the guide surface 2411 constitutes a planar inclined surface inclined at less than 90 degrees with respect to the extension direction of the pressure chamber 31, which is the direction of fluid flow, or a curved surface having a tangent inclined at less than 90 degrees with respect to the extension direction. The guide surface 2411 is a portion of the surface of the projection 241 that includes the end face (side surface) in the Y direction, a corner rising from the element wall 33, or a corner on the top 2412 side of the projection 241.

[0027] In this embodiment, each of the multiple protrusions 241 has guide surfaces 2411 formed on both ends in the second direction, i.e., the inner end and both outer sides of the pressure chamber 31. The guide surfaces 2411 are inclined surfaces that rise from the surface of the element wall 33 toward the tip (top 2412) of each protrusion, with an inclination angle of less than 90 degrees relative to the surface of the element wall 33. Specifically, the side surface from the end of the protrusion 241 that rises from the element wall 33 in the X direction toward the top 2412 constitutes the inclined surface.

[0028] The inclination angle of the inclined surface is set according to the application and various design conditions, such as an ink circulation structure or an ink non-circulation structure. For example, the projections 241 provided on both sides of each communication port of the pressure chamber 31 are configured with a trapezoidal cross-section perpendicular to the third direction, and have a uniform cross-sectional shape in the third direction.

[0029] The grooves constituting the pressure chamber 31 are not completely covered by the projections 241, and a throttling opening 242 is formed between the pair of projections 241 on both sides, connecting the pressure chamber 31 with the first common chamber 271 and the second common chamber 272. The throttling opening 242 is a slit shape extending in a third direction which is the depth direction of the pressure chamber, and its opening width in the first direction is smaller than the width of the inside of the pressure chamber 31 in the first direction, so that it is smaller than the flow path cross-sectional area of ​​the pressure chamber 31. In other words, the projections 241 partially block the communication openings at both ends in the second direction, forming a throttling section 240 that increases the flow path resistance. For example, the aperture portion 240 is formed at the entrance and exit of the pressure chamber groove by first forming a photosensitive resin film on the inner walls of the pressure chamber 31 and the air chamber 32, then, for example, placing an exposure mask on the top 222 side of the element wall 33, and performing exposure from the top 222 side through the exposure mask to harden the photosensitive resin at the desired position, and then washing away the unnecessary unexposed resin with a developer solution.

[0030] Furthermore, if the fluid resistance of the throttling section 240 is made too large, the replenishment of ink to the pressure chamber 31 after ink droplet ejection will be delayed, hindering high-speed operation. Also, the meniscus bulge varies depending on the ink viscosity, ejection volume, drive frequency, etc. Therefore, the shape of the projection 241 and the dimensions and position of the throttling opening 242 of the throttling section 240 are set to provide flow resistance according to the ink replenishment conditions and the characteristics of the meniscus bulge. Note that the throttling sections 240 on both sides may have different configurations.

[0031] The air chamber 32 is sealed on one side in the third direction by a nozzle plate 12 which is joined to the top portion 222. In addition, multiple air chambers 32 are sealed at both ends in the second direction by cover portions 23. Specifically, cover portions 23 are placed between the first common chamber 271 of the ink chamber 27 and one end of the air chamber 32 in the second direction, and between the second common chamber 272 and the other end of the air chamber 32 in the second direction, so that both ends of the air chamber 32 are separated from the ink chamber 27. As a result, the air chamber 32 constitutes an air chamber into which ink does not flow.

[0032] For example, the cover portion 23 is formed by applying a photosensitive resin to both ends of the air chamber 32 and then curing the target area.

[0033] The nozzle plate 12 is formed from, for example, a rectangular film made of polyimide. The nozzle plate 12 faces the mounting surface of the actuator base 11. Multiple nozzles 28 are formed on the nozzle plate 12, penetrating the nozzle plate 12 in the thickness direction.

[0034] Multiple nozzles 28 are provided in the same number as the pressure chambers 31, and are positioned opposite each other to the pressure chambers 31. Multiple nozzles 28 are arranged in a row along a first direction, corresponding to a pair of actuator parts 22, and are arranged in two rows. Each nozzle 28 is configured as a cylindrical shape with its axis extending in a third direction. For example, the nozzle 28 may have a constant diameter, or it may have a shape that narrows in diameter towards the center or tip. The nozzles 28 are positioned opposite each other at the midpoint in the extension direction of the pressure chambers 31 formed in the pair of actuator parts 22, and each nozzle communicates with the pressure chambers 31. The nozzles 28 are positioned one by one at a location corresponding to the space between the ends of each pressure chamber 31, for example, at the center in the longitudinal direction.

[0035] The frame 13 is formed in a rectangular frame shape, for example, from 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 bonded to the mounting surface of the actuator base 11 and the nozzle plate 12, respectively. In other words, the nozzle plate 12 is attached to the actuator base 11 via the frame 13.

[0036] The manifold 18 is joined to the actuator base 11 on the side opposite to the nozzle plate 12. Inside the manifold 18, an ink supply section is formed, which is a flow path communicating with the supply hole 25, and an ink discharge section is formed, which is a flow path communicating with the discharge hole 26.

[0037] The circuit board 17 is a film carrier package (FCP). The circuit board 17 has a flexible resin film 51 on which multiple wirings are formed, and an IC 52 connected to the multiple wirings of the film 51. The IC 52 is electrically connected to the electrode layer 34 via the wirings and pattern wirings 211 of the film 51.

[0038] Within 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 divided into three sections in the second direction by two actuator sections 22, and has two second common chambers 272 as a common chamber through which the discharge holes 26 open, and a first common chamber 271 as a common chamber through which the supply holes 25 open. The first common chamber 271 and the second common chambers 272 are in communication with a plurality of pressure chambers 31.

[0039] In the inkjet head 10 configured as described above, ink circulates between the ink tank and the ink chamber 27 through the supply hole, pressure chamber, and discharge hole. For example, a signal input from the control unit of the inkjet printer causes the drive IC 52 to apply a drive voltage to the electrode layer 34 of the pressure chamber 31 via the wiring of the film 51, thereby creating a potential difference between the electrode layer 34 of the pressure chamber 31 and the electrode layer 34 of the air chamber 32, and selectively deforming the element wall 33 in shear mode. By deforming the element wall 33 formed between the pressure chamber 31 and the air chamber 32 in accordance with the drive signal, the volume of the pressure chamber 31 is changed.

[0040] As the element wall 33 undergoes shear-mode deformation, the volume of the pressure chamber 31 in which the electrode layer 34 is provided increases, and the pressure decreases. As a result, ink from the ink chamber 27 flows into the pressure chamber 31.

[0041] With the volume of the pressure chamber 31 increased, IC 52 applies a reverse potential drive voltage to the electrode layer 34 of the pressure chamber 31. This causes the element wall 33 to undergo shear mode deformation, reducing the volume of the pressure chamber 31 where the electrode layer 34 is located and increasing the pressure. As a result, the ink in the pressure chamber 31 is pressurized and ejected from the nozzle 28.

[0042] As a method for manufacturing the inkjet head 10, first, a piezoelectric member with multiple grooves is attached to a plate-shaped substrate 21 with an adhesive or the like, and then an actuator base 11 having a predetermined outer shape is formed by machining using a dicing saw or slicer. Alternatively, for example, a block-shaped base member with the thickness of multiple sheets may be formed in advance and then divided to manufacture multiple actuator bases 11 of the predetermined shape.

[0043] Next, electrode layers 34 and pattern wiring 211 are formed on the inner surfaces of the grooves constituting the pressure chamber 31 and air chamber 32, and on the surface of the substrate 21. As a result, electrode layers 34 and pattern wiring 211 are formed at predetermined locations on the surface of the actuator base 11.

[0044] Next, an aperture portion 240, which is a communication opening with greater flow resistance than the inside of the pressure chamber 31, is formed at the end of the pressure chamber 31. For example, a method for forming the aperture portion 240 includes a film formation process in which a film of photosensitive resin is formed in the grooves constituting the pressure chamber 31, and a molding process in which the film is formed by exposure and development.

[0045] Specifically, as a film formation process, a photosensitive resin is applied to the inner wall of the pressure chamber 31 to form a resin film. At the same time, a cover portion 23 is formed at a predetermined location using the photosensitive resin to seal both ends of the air chamber 32. As a result, a resin film is formed on the surfaces of the element walls 33 on both sides that constitute the groove and on the bottom surface of the groove at both ends of the pressure chamber 31 and both ends of the air chamber 32. Next, as a molding process, the resin films at both ends of the pressure chamber 31 are molded by exposure and development. In the molding process, a photomask having an exposure pattern in which the area to be molded is cured is placed on top, and exposure is performed from, for example, the top surface side of the element wall 33 where the element wall 33 opens, in the depth direction (third direction) of the pressure chamber 31, and the uncured resin film is removed with a developer. The exposure direction and exposure intensity at this time are set as appropriate. As an example, by setting the exposure direction in the depth direction of the pressure chamber 31, the protrusions 241 on both sides can be exposed and molded simultaneously.

[0046] As a result, a resin film projection 241 is formed at the inlet and outlet of the pressure chamber 31, and a constricted portion 240 is formed between the projections 241 on both sides.

[0047] The cover portion 23 may be formed before or after the aperture portion 240 is formed.

[0048] Then, the actuator base 11 is assembled to the manifold 18, and the frame 13 is attached to one side of the substrate 21 of the actuator base 11 using a thermoplastic resin adhesive sheet.

[0049] Next, the assembled frame 13, the top 222 of the element wall 33 of the actuator section 22, and the nozzle plate 12 side of the projection 241 are polished so that they are on the same plane. Then, the nozzle plate 12 is attached by bonding it to the polished surfaces of the top 222 of the element wall 33, the frame 13, and the projection 241. At this time, the nozzle 28 is positioned so that it faces the pressure chamber 31. Furthermore, as shown in Figure 1, the inkjet head 10 is completed 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 via a flexible printed circuit board.

[0050] An example of an inkjet printer 100 equipped with an inkjet head 10 will be described below with reference to Figure 16. The inkjet printer 100 comprises a housing 111, a media supply unit 112, an image forming unit 113, a media discharge unit 114, a transport device 115, and a control unit 116.

[0051] The inkjet printer 100 is a liquid ejection device that performs image formation processing on paper P by ejecting a liquid such as ink while transporting paper P, for example, as a recording medium to be ejected, along a predetermined transport path A from the media supply unit 112 through the image forming unit 113 to the media ejection unit 114.

[0052] The housing 111 constitutes the outer casing of the inkjet printer 100. The housing 111 is provided with an outlet at a predetermined location for ejecting paper P to the outside.

[0053] The media supply unit 112 is equipped with multiple paper feed cassettes and is configured to hold multiple sheets of paper P of various sizes stacked on top of each other.

[0054] The media discharge unit 114 includes a paper output tray configured to hold the paper P discharged from the discharge port.

[0055] The image forming unit 113 includes a support unit 117 that supports the paper P, and a plurality of head units 130 that are positioned opposite each other above the support unit 117.

[0056] The support unit 117 includes a conveyor belt 118 provided in a loop shape in a predetermined area where image formation is performed, a support plate 119 that supports the conveyor belt 118 from the back, and a plurality of belt rollers 120 provided on the back of the conveyor belt 118.

[0057] During image formation, the support unit 117 supports the paper P on the holding surface, which is the upper surface of the conveyor belt 118, and conveys the paper P downstream by moving the conveyor belt 118 at a predetermined timing by the rotation of the belt roller 120.

[0058] The head unit 130 comprises multiple (four-color) inkjet heads 10, ink tanks 132 acting as liquid tanks mounted on each inkjet head 10, a connecting channel 133 connecting the inkjet heads 10 and the ink tanks 132, and a circulation pump 134 which is a circulation unit. The head unit 130 is a circulating type head unit that constantly circulates liquid in the ink tanks 132 and in the pressure chamber 31, air chamber 32, and ink chamber 27 built inside the inkjet heads 10.

[0059] In this embodiment, the system includes four inkjet heads 10 for cyan, magenta, yellow, and black, and ink tanks 132 each containing ink for one of these colors. The ink tanks 132 are connected to the inkjet heads 10 by a connecting channel 133. The connecting channel 133 includes 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.

[0060] Furthermore, a negative pressure control device, such as a pump (not shown), is connected to the ink tank 132. The negative pressure control device controls the negative pressure inside the ink tank 132 in accordance with the head value between the inkjet head 10 and the ink tank 132, thereby forming a meniscus of a predetermined shape with the ink supplied to each nozzle 28 of the inkjet head 10.

[0061] The circulation pump 134 is a liquid transfer pump, for example, a piezoelectric pump. The circulation pump 134 is installed in the supply channel. The circulation pump 134 is connected to the drive circuit of the control unit 116 by wiring and is configured to be controllable by the CPU (Central Processing Unit). The circulation pump 134 circulates the liquid in the circulation channel, which includes the inkjet head 10 and the ink tank 132.

[0062] The transport device 115 transports the paper P along a transport path A, which runs from the media supply unit 112 through the image forming unit 113 to the media discharge unit 114. The transport device 115 comprises a plurality of guide plate pairs 121 and a plurality of transport rollers 122 arranged along the transport path A.

[0063] Each of the multiple guide plate pairs 121 comprises a pair of plate members positioned opposite each other with the paper being transported P in between, and guides the paper P along the transport path A.

[0064] The transport roller 122 is driven and rotated by the control unit 116 to feed the paper P downstream along the transport path A. Sensors for detecting the paper transport status are placed at various points along the transport path A.

[0065] The control unit 116 includes a control circuit such as a CPU which acts as a controller, a ROM (Read Only Memory) for storing various programs, a RAM (Random Access Memory) for temporarily storing various variable data and image data, and an interface unit for inputting data from the outside and outputting data to the outside.

[0066] In the inkjet printer 100 configured as described above, when the control unit 116 detects a print command from a user operating the operation input unit on the interface, for example, it drives the transport device 115 to transport the paper P and drives the inkjet head 10 by outputting a print signal to the head unit 130 at a predetermined timing. In its ejection operation, the inkjet head 10 sends a drive signal to the IC using an image signal corresponding to the image data, applies a drive voltage to the electrode layer 34 of the pressure chamber 31 via wiring, selectively drives the element wall 33 of the actuator unit 22 to eject ink from the nozzle 28, and forms an image on the paper P held on the transport belt 118. In addition, in its liquid ejection operation, the control unit 116 drives the circulation pump 134 to circulate liquid through a circulation channel that passes between the ink tank 132 and the inkjet head 10. Through the circulation operation, the ink in the ink tank 132 is supplied from the supply hole 25 to the first common chamber 271 of the ink chamber 27 through the ink supply section 25 of the manifold 18, when the circulation pump 134 is driven. This ink is supplied to the multiple pressure chambers 31 and multiple air chambers 32 of the pair of actuator sections 22. The ink flows through the pressure chambers 31 and air chambers 32 to the second common chamber 272 of the ink chamber 27. This ink is then discharged from the discharge hole 26 through the ink discharge section of the manifold 18 to the ink tank 132.

[0067] According to the embodiment described above, the formation of a throttling at the inlet and outlet of the pressure chamber 31 improves ejection stability. Furthermore, in the inkjet head 10, the projection 241 provided at the communication port of the pressure chamber 31 has a guide surface that is inclined or curved toward the inside of the pressure chamber 31, thereby promoting the discharge of air bubbles B and improving print quality. In other words, if a rectangular parallelepiped-shaped throttling portion is provided at the inlet and outlet of the pressure chamber using a photosensitive resin as a means of increasing fluid resistance, air bubbles B may accumulate at the corners of the element wall 33 and the projection 241, potentially reducing print quality due to bubble growth (cavitation) or failure to eject due to pressure vibration malfunctions during high-speed driving. However, by configuring the end face (side), corner, or edge of the projection 241 in the Y direction to have an inclined or curved guide surface, the accumulation of air bubbles B can be prevented, and print quality can be ensured.

[0068] Furthermore, the openings of the diaphragm 240 that open into the first common chamber 271 and the second common chamber 272, which are common chambers of the pressure chamber 31, are smaller than the flow path cross-sectional area of ​​the pressure chamber 31. As a result, the meniscus bulge is reduced when liquid is ejected in the inkjet head 10. Consequently, the meniscus recovers faster, reducing the impact on the next print and improving ejection stability.

[0069] Figure 7 shows Test Example 1 of an inkjet head 110 equipped with an aperture (aperture section 240) and Test Example 2 of an inkjet head 1010 without an aperture. Figure 8 shows the frequency characteristics of the inkjet head 110 with an aperture according to Test Example 1, and Figure 9 shows the frequency characteristics of the inkjet head 1010 without an aperture as Comparative Example 2. In Figures 8 and 9, the relationship between nozzle ejection speed and frequency is shown for 1 drop and 3 drop cases, respectively.

[0070] Here, the inkjet head 110 in Test Example 1 is a side-shooter type in which both sides of the second direction, which is the extension direction of the pressure chamber 31, communicate with a common chamber, and the nozzle 28 opens in the middle of the extension direction of the pressure chamber 31. Also, Test Example 1 is an example that demonstrates the effect of the diaphragm 240, and the projection 241 of Test Example 1 does not have a guide surface 2411.

[0071] As shown in Figure 9, in the inkjet head 1010 of Test Example 2, the ejection speed is flat in the low-frequency range, but tends to decrease as the frequency increases, resulting in a difference in ejection speed between the low-frequency and high-frequency ranges. In 1 drop of the inkjet head 1010 of Test Example 2, the ejection speed is flat up to 25 kHz, but tends to decrease as the frequency increases above 25 kHz. Also, in 3 drop of the inkjet head 1010 of Test Example 2, the ejection speed is flat up to 15 kHz, but tends to decrease as the frequency increases above 15 kHz. Therefore, a shift in the landing position occurs depending on the printing pattern. Such a large difference in ejection speed causes a long time for the meniscus to settle, leading to a decrease in print quality, and thus making high-speed driving impossible.

[0072] On the other hand, as shown in Figure 8, in the inkjet head 110 with an aperture, the ejection speed tends to be flat for both 1-drop and 3-drop applications. This is because the fluid resistance between the common chamber and the nozzle increases, and the meniscus rise decreases.

[0073] Figure 10 shows the simulation results of meniscus recovery for Test Example 1, in which an aperture is provided in the pressure chamber, and Test Example 2, in which an aperture is not provided. According to Figure 10, in the case of low frequency, there is sufficient time between the ejection of one ink droplet and the ejection of the next droplet, and regardless of whether an aperture is provided, it is possible to wait for the meniscus to recover before ejection in a stable state. On the other hand, in the case of high frequency, the time between the ejection of one dot (ink droplet) and the ejection of the next droplet is short, so the ejection of the next droplet begins before the meniscus recovers. For this reason, in the case of the inkjet head 1010 without an aperture, the meniscus bulge becomes large after ejection, and the meniscus cannot recover before the ejection of the next droplet, resulting in a decrease in ejection speed. In contrast, when an aperture is provided, the bulge of the meniscus is smaller, so the meniscus recovers faster and the impact on the next droplet is reduced. Therefore, from these simulation results, it can be said that providing an aperture between the pressure chamber 31 and the common chamber leads to improved ejection stability of the inkjet head 110.

[0074] Figure 11 is an explanatory diagram of a side-shooter type inkjet head 110 as Test Example 1, and a shear-mode shared-wall type end-shooter type inkjet head 2010 as Test Example 3, in which the ink inlet / outlet is formed at one end and the nozzle is formed at the other end.

[0075] Figures 12 to 15 show a comparison of the simulation characteristics of an end-shooter type inkjet head 2010 (Test Example 3) and an inkjet head 110 (Side-shooter type) (Test Example 1), when an aperture is provided. Figure 12 shows the drive waveform, Figure 13 shows the nozzle flow velocity vibration, Figure 14 shows the ejection volume, and Figure 15 shows the meniscus return characteristics.

[0076] Furthermore, the inkjet head 2010 in Test Example 3 is of the end-shooter type, in which one end in the second direction, which is the extension direction of the pressure chamber 31, communicates with a common chamber, the other end is closed, and a nozzle opens at the end of the flow path. In other words, the inkjet head 2010 constitutes a flow path from one side of the second direction toward the nozzle 28.

[0077] In the case of Test Example 3, the end-shooter type inkjet head 2010, which supplies ink from one side, and the side-shooter type inkjet head 110, which supplies ink from both sides, the drive voltage is lowest when the ejection volume, nozzle flow velocity vibration, and meniscus return characteristics are matched for the side-shooter type configuration with both sides supplying ink. Therefore, it can be said that the side-shooter type has a significant advantage over the single-sided supply in terms of drive efficiency. In other words, the so-called side-shooter type inkjet head 110, which has the nozzle in the center of the pressure chamber and the ink inlet and outlet at both ends, has better ejection efficiency than the end-shooter type inkjet head 2010.

[0078] Furthermore, according to the above embodiment, the aperture portion 240 can be formed by depositing a photosensitive resin film in the groove of the actuator portion 22 and patterning it by exposure treatment, thus enabling the formation of the aperture portion 240 with fewer steps, at low cost, and easily. Moreover, since the thickness and shape of the protrusion portion 241 can be selected relatively freely by exposure and development, it is also easy to freely design the fluid resistance of the aperture. In addition, in the above embodiment, since the side portion 221 of the actuator portion 22 constitutes an inclined surface, there are fewer constraints on the exposure direction, and exposure and development treatments become easier.

[0079] It should be noted that the present invention is not limited to the embodiments described above, and the components can be modified and implemented in practice without departing from the spirit of the invention.

[0080] In the above embodiment, the throttling portion 240 that increases flow resistance is configured to have a pair of protrusions 241 formed on the wall surfaces of the element walls 33 on both sides of the pressure chamber 31, but the shape of the throttling portion 240 is not limited to this. For example, the protrusions may be formed on a part of the bottom side of the pressure chamber 31 or on a part of the nozzle plate 12 side, or the area on the bottom side of the pressure chamber 31 may be partially filled with a photosensitive resin. For example, the throttling opening 242 is a slit shape extending in a third direction which is the depth direction of the pressure chamber, but it may extend in other directions, or it may be a shape including a circle or an oval. In addition, the throttling portions 240 on both sides may have different configurations. For example, by forming a throttling portion 240 with a protrusion 241 at at least one communication opening of the pressure chamber 31 which communicates with common chambers 271 and 272 on both sides, the discharge performance can be improved and the throttling portion 240 can be formed inexpensively and easily.

[0081] Furthermore, although the cover portion 23 and the projection portion 241 are formed inside the grooves that form the pressure chamber 31 and the air chamber 32 and fill a part of the grooves, the design is not limited to this. For example, on the side surface of the actuator, a cover portion 23 that closes the air chamber 32 and a throttling portion 240, such as a projection portion 241 that partially closes the communication opening of the pressure chamber 31, may be formed outside the grooves that form the pressure chamber 31 and the air chamber 32.

[0082] In the above embodiment, an example was shown in which an actuator section 22 having multiple grooves is arranged on the main surface portion of the substrate 21, but the embodiment is not limited to this. For example, the actuator may be provided on the end face of the substrate 21. Also, the number of nozzle rows is not limited to the above embodiment, and a configuration with one row or three or more rows may be used.

[0083] Furthermore, although the above embodiment illustrates an actuator base 11 equipped with a laminated piezoelectric body made of piezoelectric material on a substrate 21, the actuator base is not limited to this. For example, the actuator base 11 may be formed using only piezoelectric material without a substrate. Also, instead of using two piezoelectric material members, one piezoelectric material may be used. The air chamber 32 may also be in communication with a common chamber, such as a first common chamber 271 or a second common chamber 272. The supply side and discharge side may also be reversed, or they may be configured to be switchable.

[0084] Furthermore, in the above embodiment, as an example, a circulating inkjet head is provided in which one side of the pressure chamber 31 is the supply side and the other side is the discharge side, and the fluid in the first common chamber flows in from one side of the pressure chamber and flows out from the other side. However, the invention is not limited to this. For example, a non-circulating type may be used. Alternatively, for example, the common chambers on both sides of the pressure chamber 31 may be the supply sides, and fluid may flow in from both sides. That is, fluid may flow in from both sides of the pressure chamber 31 and flow out from a nozzle 28 located in the center of the pressure chamber 31. Even in this case, by providing throttling portions 240 at the communication ports that serve as inlets on both sides of the pressure chamber 31, fluid resistance can be increased and discharge efficiency can be improved. Also, the configuration of the throttling portions 240 formed at each end may be different.

[0085] Furthermore, although the above embodiment shows an example in which the throttling portion 240 is formed at both ends in the extending direction of the pressure chamber 31, it is not limited to this, and the throttling portion 240 may be formed on only one of the two inlets / outlets on both sides of the pressure chamber 31 that communicate with the common chambers 271 and 272 at both ends. For example, the throttling portion 240 that increases the fluid resistance compared to the inside of the pressure chamber 31 may be formed at one end, and the other end may have the same fluid resistance as the inside of the pressure chamber 31, for example, the same cross-sectional area of ​​the communication opening as the cross-sectional area of ​​the inside of the pressure chamber 31. In the above embodiment, a side-shooter type in which both sides of the pressure chamber 31 communicate with the ink chamber was illustrated, but the invention is not limited to this. For example, an end-shooter type in which only one side of the pressure chamber 31 communicates with the ink chamber 27 may also be used.

[0086] Furthermore, although the above embodiment shows an example in which protrusions 241 are formed on both sides, it is not limited to this. For example, the protrusions 241 may be formed only on one side of the element wall 33.

[0087] Figure 17 is an explanatory diagram showing a part of the configuration and fluid flow of an inkjet head 1001 according to the second embodiment. In this embodiment, the guide surface 2411 is formed only on the inside side of the pressure chamber, rather than on both sides in the extension direction of the projection 241. The other shapes are the same as in the above embodiment. Even with this structure, by having a curved or inclined guide surface 2411 on the surface of the projection 241, the fluid can be guided, suppressing the accumulation of bubbles B and promoting the discharge of bubbles B.

[0088] Figure 18 is an explanatory diagram showing some of the configuration and fluid flow of an inkjet head 1002 according to the third embodiment. This embodiment has a so-called double-sided supply structure in which fluid is supplied from both sides of the pressure chamber 31. The other configurations are the same as those of the first embodiment described above. Even in this structure, by having a curved or inclined guide surface 2411 on the surface of the projection 241, the fluid can be guided, suppressing the accumulation of bubbles B and promoting the discharge of bubbles B.

[0089] Figure 19 is an explanatory diagram showing a part of the configuration and fluid flow of an inkjet head 1003 according to the fourth embodiment. This embodiment has a so-called double-sided supply structure in which fluid is supplied from both sides of the pressure chamber 31, and the guide surface 2411 is formed only on the inside of the pressure chamber 31. The other configurations are the same as those of the first to third embodiments described above. Even in this structure, by having a curved or inclined guide surface 2411 on the surface of the projection 241, the fluid can be guided, suppressing the accumulation of bubbles B and promoting the discharge of bubbles B.

[0090] Figure 20 is an explanatory diagram showing some of the configuration and fluid flow of an inkjet head 1004 according to the fifth embodiment. This embodiment is a so-called double-sided supply structure in which fluid is supplied from both sides of the pressure chamber 31, and a projection 241 is formed on only one side of the pair of element walls 33 that form the pressure chamber 31, while the other side does not have a projection 241. The other configurations are the same as those of the third embodiment described above. Even in this structure, by having a curved or inclined guide surface 2411 on the surface of the projection 241, the fluid can be guided, suppressing the accumulation of bubbles B and promoting the discharge of bubbles B.

[0091] Figure 21 is an explanatory diagram showing a part of the configuration and fluid flow of an inkjet head 1005 according to the sixth embodiment. This embodiment has a so-called double-sided supply structure in which fluid is supplied from both sides of the pressure chamber 31. In this configuration, at each communication port, a projection 241 is formed on only one side of the pair of element walls 33 that form the pressure chamber 31. Specifically, at the communication port on one side in the extension direction, a projection 241 is formed on the element wall 33 on one side in the parallel direction, and at the communication port on the other side in the extension direction, a projection 241 is formed on the element wall 33 on the other side in the parallel direction. That is, at both ends, projections 241 are provided on opposite sides of the opposing pair of element walls 33. The other configurations are the same as in the third embodiment described above. Even with this structure, by having a curved or inclined guide surface 2411 on the surface of the projection 241, the fluid can be guided, suppressing the accumulation of bubbles B and promoting the discharge of bubbles B.

[0092] Figure 22 is an explanatory diagram showing a part of the configuration and fluid flow of an inkjet head 1006 according to the seventh embodiment. This embodiment is a so-called end-shooter type inkjet head in which one side of the pressure chamber in the extension direction communicates with a common chamber 271, and the other side is closed or covered by a nozzle plate 12. In this embodiment, the liquid discharge direction is the extension direction (Y direction). For example, in this embodiment, a nozzle plate 12 having a nozzle 28 is provided at the other end of the pressure chamber 31 in the extension direction. In this embodiment, at the communication port to which the fluid is supplied, protrusions 241 are formed on each of the pair of element walls 33 that form the pressure chamber 31. The other configurations are the same as in the first embodiment described above. Even with such a structure, by having a curved or inclined guide surface 2411 on the surface of the protrusion 241, the fluid can be guided, suppressing the accumulation of bubbles B and promoting the discharge of bubbles B. Furthermore, as another example of an end-shooter type inkjet head, in an inkjet head where the other side of the pressure chamber 31 in the Y direction is closed and the nozzle plate 12 is positioned opposite the pressure chamber 31 in the Z direction, as shown in Comparative Example 3 in Figure 11, the surface of the projection 241 may be provided with a guide surface 2411 that is inclined or curved with respect to the element wall 33.

[0093] Figure 23 is an explanatory diagram showing some of the configuration and fluid flow of an inkjet head 1007 according to the eighth embodiment. This embodiment is a so-called end-shooter type inkjet head in which one side of the pressure chamber in the extension direction communicates with a common chamber 271. In this embodiment, the liquid discharge direction is the extension direction (Y direction). For example, in this embodiment, a nozzle plate 12 having a nozzle 28 is arranged at the other end of the pressure chamber 31 in the extension direction. In this embodiment, at the communication port to which the fluid is supplied, a projection 241 is formed on only one side of the pair of element walls 33 that form the pressure chamber 31. The other configurations are the same as in the seventh embodiment described above. Even with such a structure, by having a curved or inclined guide surface 2411 on the surface of the projection 241, the fluid can be guided, suppressing the accumulation of bubbles B and promoting the discharge of bubbles B.

[0094] Furthermore, the shape of the projection 241 is not limited to the above and can be changed as appropriate. In the above embodiment, an example was shown in which the guide surface 2411 is inclined, but this is not limited to this, and the surface of the projection 241 may have a curved surface, for example, as shown in the inkjet heads 1008 and 1009 in Figures 24 and 25. Also, in the above first embodiment, an example was shown in which the guide surface 2411 is formed at the corner on the top 2412 side of the projection 241, but instead of this, or in addition to this, the guide surface 2411 may be formed at the corner portion on the element wall 33 side. Moreover, not only the corners and edges, but the entire surface of each projection 241 may be configured to be curved.

[0095] Figure 24 is an explanatory diagram showing a part of the configuration and fluid flow of an inkjet head 1008 according to the ninth embodiment. In this embodiment, the projection 241 has a curved surface as a guide surface 2411 at the corner on the top 2412 side of the projection 241. The tangential direction of the guide surface 2411 at the corner on the top 2412 side of the projection 241 is inclined at less than 90 degrees with respect to the extension direction.

[0096] Figure 25 is an explanatory diagram showing a part of the configuration and fluid flow of an inkjet head 1009 according to the tenth embodiment. In this embodiment, the projection 241 has a curved surface as a guide surface 2411 at the corner portion on the element wall 33 side. The tangential direction of the guide surface 2411 at the corner portion on the element wall 33 side is inclined at less than 90 degrees with respect to the extension direction. In one projection 241, one guide surface 2411 in the fluid flow direction may have a curved surface, and the other guide surface 2411 may be inclined at less than 90 degrees with respect to the extension direction.

[0097] In the above embodiment, a shear-mode sheared-wall type inkjet head 10 in which pressure chambers 31 and air chambers 32 are arranged alternately was illustrated, but the invention is not limited to this. For example, a configuration without air chambers may also be used. Furthermore, the invention is not limited to the shear-mode sheared-wall type, but is also applicable to other types such as the piston type. For example, in these embodiments as well, the same effects as in the above embodiment can be obtained by providing a throttling wall with an inclined or curved guide surface at least on the inner surface of the pressure chamber at the communication port between the common chamber and the pressure chamber. Furthermore, the liquid to be dispensed is not limited to printing ink; for example, it could be a device that dispenses a liquid containing conductive particles for forming wiring patterns on a printed circuit board.

[0098] Furthermore, while the above embodiment shows an example of the inkjet head being used in a liquid ejection device such as an inkjet printer, it is not limited to this, and can also be used in 3D printers, industrial manufacturing machinery, and medical applications, enabling miniaturization, weight reduction, and cost reduction.

[0099] According to at least one embodiment described above, it is possible to provide a liquid dispensing head and a method for manufacturing a liquid dispensing head that can ensure stable dispensing characteristics.

[0100] In addition, several embodiments of the present invention have been described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be carried out in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. The following is an appended description equivalent to the invention described in the claims of the original application. (1) An actuator unit having multiple pressure chambers, A throttling section is provided at the communication opening between a common chamber communicating with the pressure chamber and the pressure chamber, and includes a throttling wall having at least an inclined or curved guide surface on the inner surface of the pressure chamber, A liquid dispensing head equipped with a liquid dispensing head. (2) The aforementioned throttling wall is a projection provided on the wall portion constituting the pressure chamber, The guide surface is such that the surface of a portion of the tapered wall, including at least one of the side, the corner on the wall side, and the corner on the top side, or the tangent to the surface of such portion, is inclined at less than 90 degrees with respect to the surface of the wall. The liquid discharge head according to (1), wherein the throttling portion increases the fluid resistance at the communication port compared to that in the pressure chamber. (3) This is a side-chute type in which both sides in the extension direction intersecting the direction of arrangement of the pressure chambers communicate with a common chamber. The liquid discharge head according to (1), wherein the constriction walls are formed at the communication ports on both sides in the extending direction of the pressure chamber. (4) The pressure chamber is of an end-shooter type, in which one side in the extension direction intersecting the alignment direction communicates with the common chamber. The liquid discharge head according to (1), wherein the constriction wall is formed at the communication port on one side of the pressure chamber. (5) The throttling wall is made of a photosensitive resin and is provided on a pair of wall portions that constitute the pressure chamber, which are arranged on one side and the other side in the direction in which the plurality of pressure chambers are arranged in the communication port, respectively, according to any one of (1) to (4). [Explanation of symbols]

[0101] 10, 1001~1009, 1010…Inkjet head, 11…Actuator base, 12…Nozzle plate, 13…Frame, 17…Circuit board, 18…Manifold, 21…Substrate, 22…Actuator section, 23…Cover section, 25…Supply hole, 26…Discharge hole, 27…Ink chamber, 31…Pressure chamber, 32…Air chamber, 33…Element wall (wall section), 34…Electrode layer, 51…Film, 52…Drive IC chip, 100…Inkjet printer, 111…Housing, 112…Media supply section, 113…Image forming section, 11 4...Media discharge section, 115...Conveying device, 116...Control unit, 117...Support section, 118...Conveying belt, 119...Support plate, 120...Belt roller, 121...Guide plate pair, 122...Conveying roller, 130...Head unit, 132...Ink tank, 133...Connecting channel, 134...Circulation pump, 211...Pattern wiring, 221...Side section, 222...Top section, 240...Constriction section, 241...Protrusion, 2411...Guide surface, 2412...Top section, 242...Constriction opening, 271...First common chamber, 27...Ink chamber, 272...Second common chamber.

Claims

1. An independently driven actuator unit having a plurality of element walls made of piezoelectric material, grooves forming pressure chambers and air chambers between the plurality of element walls, and in the direction in which the plurality of pressure chambers and the plurality of air chambers are arranged alternately, A throttling section is provided at the communication opening between a common chamber communicating with a plurality of the aforementioned pressure chambers and the pressure chambers, and includes a throttling wall having a guide surface that is inclined or curved on at least the inner surface of the pressure chamber, In a side-chute type system, both sides of the multiple pressure chambers in the extending direction each communicate with a common chamber, and liquid is supplied to the multiple pressure chambers from the common chambers on both sides in the extending direction. The aforementioned throttling wall is made of a photosensitive resin and is a projection provided on a pair of element walls that constitute the pressure chamber, respectively, which are arranged on one side and the other side in the direction in which the plurality of pressure chambers are arranged at the communication openings on both sides in the extending direction of the pressure chamber. Liquid dispensing head.

2. The guide surface is such that the surface of a portion of the constricted wall including at least one of the side surface, the corner on the element wall side, and the corner on the top side, or the tangent to the surface of said portion, is inclined at less than 90 degrees with respect to the surface of the element wall. The liquid discharge head according to claim 1, wherein the throttling portion increases the fluid resistance at the communication port compared to the pressure chamber.

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