Liquid dispensing head

Abstract

To provide a liquid discharge head which can secure stable discharge characteristics.SOLUTION: A liquid discharge head according to one embodiment includes: actuator parts; a nozzle plate; and contracted parts. The actuator part has multiple pressure chambers. The nozzle plate is arranged facing the multiple pressure chambers. The contracted part is provided at a communication port between a common chamber communicating with the pressure chambers and the pressure chamber. The contracted part forms a contracted port in which passage resistance is larger than that in the pressure chamber and includes a lid part disposed at the nozzle plate side of the contracted port.SELECTED DRAWING: Figure 4

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 increasing the speed and the amount of droplets ejected have become issues. 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 three-cycle drive in which one-third of a plurality of arranged chambers are simultaneously driven as pressure chambers is common. Also, an independent drive head in which both sides of a pressure chamber to be driven are dummy pressure chambers and one pressure chamber is driven by two independent drive columns has been developed. 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 meniscus swells due to overshoot at the nozzle. The smaller the flow path 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 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 discharge head according to one embodiment comprises an actuator section, a nozzle plate, and a throttling section. The actuator section has a plurality of pressure chambers. The nozzle plate is arranged opposite to the plurality of pressure chambers. The throttling section is provided at the communication port between a common chamber communicating with the pressure chambers and the pressure chambers. The throttling section forms a throttling opening with a greater flow resistance than the pressure chambers and includes a lid section positioned on the nozzle plate side of the throttling opening. The actuator portion comprises a plurality of side wall portions arranged in a first direction, with a plurality of grooves formed between the plurality of side wall portions that constitute the pressure chamber and open toward the nozzle plate side, and the throttling portion is made of a photosensitive resin and is positioned at the end of the groove in a second direction intersecting the first direction, and has a pair of protrusions that project into the groove from a pair of side wall portions that constitute both sides of the pressure chamber in the first direction, thereby narrowing the width dimension of the communication opening in the first direction to the width dimension of the pressure chamber in the first direction, and a cover portion provided at the nozzle plate side end of the opening formed between the pair of protrusions, which closes the nozzle plate side opening of the throttling portion, and there is an adhesive layer between the side wall portions and the cover portion and the nozzle plate. [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 the manufacturing method of the inkjet head. [Figure 7] A schematic diagram showing an inkjet printer according to this embodiment. [Modes for carrying out the invention]

[0008] The configuration of the inkjet head 10, which is a liquid ejection head according to the first embodiment, will be described below with reference to Figures 1 to 6. Figure 1 is a perspective view showing the inkjet head according to the first embodiment, and Figure 2 is an exploded perspective view of a part of the inkjet head. Figure 3 is an enlarged perspective view showing a part of the configuration of the inkjet head, and Figures 4 and 5 are enlarged cross-sectional views showing a part of the configuration of the inkjet head. Figure 6 is an explanatory diagram showing a method for manufacturing the inkjet head, and Figure 7 is a schematic diagram showing an inkjet printer, which is a liquid ejection device. In the figures, X, Y, and Z indicate the first, second, and third directions, respectively, which are orthogonal to each other. In this embodiment, the directions are described based on the orientation in which the parallel direction of the nozzles 28 and pressure chamber 31 of the inkjet head 10 is along the X axis, the extension direction of the pressure chamber 31 is along the Y axis, and the liquid ejection direction is along the Z axis, but the description is not limited to this.

[0009] The inkjet head 10 shown in Figures 1 to 5 is a device for ejecting ink and is installed, for example, inside an inkjet printer. The inkjet head 10 is a share-mode share-wall type inkjet head. For example, the inkjet head 10 is an independently driven inkjet head in which pressure chambers 31 and air chambers 32 are arranged alternately. The air chambers 32 are air chambers to which ink is not supplied and do not have nozzles 28. In this embodiment, the inkjet head 10 is a so-called side-shooter type inkjet head.

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

[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 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 and a pair of actuator units 22.

[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 sections 22, and are arranged along the longitudinal direction of the actuator sections 22. The supply holes 25 communicate with the ink supply section of the manifold 18. The supply holes 25 are connected to the ink tank via the ink supply section. The supply holes 25 supply ink from the ink tank to the ink chamber 27. Note that the supply holes 25 are not limited to multiple circular holes as shown in Figure 2, but may be a single elongated hole that is long in the X direction along the actuator section 22.

[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] The pair of actuator units 22 are adhered to the mounting surface of the substrate 21. The pair of actuator units 22 are provided on the substrate 21 in two rows with the supply holes 25 interposed therebetween. Each actuator unit 22 is formed by, for example, two plate-shaped piezoelectric bodies formed 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 unit 22 is adhered to the mounting surface of the substrate 21 by, for example, an epoxy-based adhesive having thermosetting properties. As shown in FIG. 2, the actuator units 22 are arranged in parallel in the ink chamber 27 corresponding to the nozzles 28 arranged in two rows. The actuator unit 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 width of the actuator unit 22 in the short side direction gradually increases from the top surface portion side toward the substrate side. The cross-sectional shape along the direction (short side direction) orthogonal to the longitudinal direction of the actuator unit 22 is formed in a trapezoidal shape. The side surface portion 221 of the actuator unit 22 has inclined surfaces inclined with respect to the second direction and the third direction. The top surface portion 222 of the actuator unit 22 is adhered to the nozzle plate 12 via an adhesive layer 291.

[0019] The actuator unit 22 includes a plurality of pressure chambers 31, a plurality of air chambers 32, and throttle portions 240 provided at the inlets and outlets of each pressure chamber 31, respectively. The actuator unit 22 has a plurality of element walls 33 (side wall portions), and between the element walls 33, there are grooves 14 that constitute the pressure chambers 31 and the air chambers 32. In other words, the element walls 33 are formed as driving elements between the grooves 14 that form the pressure chambers 31 and the air chambers 32.

[0020] As shown in FIGS. 1 to 5, the bottom surface portion of the groove 14 and the main surface of the substrate 21 are connected by the inclined side surface portion 221. The plurality of pressure chambers 31 and the plurality of air chambers 32 are alternately arranged. The pressure chambers 31 and the air chambers 32 extend in directions intersecting the longitudinal direction of the actuator portion 22, and a plurality of them are arranged in parallel in the longitudinal direction (X direction) of the actuator portion 22. That is, the arrangement direction of the plurality of pressure chambers 31 and air chambers 32 is along the X direction. In the present embodiment, for example, the groove 14 is configured such that the width dimension in the X direction is constant in the depth direction along the Z direction, and the cross section orthogonal to the extending direction, which is the Y direction, is rectangular.

[0021] Note that the shapes of the pressure chamber 31 and the air chamber 32 may be different. The element wall 33 is formed between the pressure chamber 31 and the air chamber 32, and by being deformed according to the drive signal, the volume of the pressure chamber 31 is changed.

[0022] Electrode layers 34 are provided on the inner wall surfaces of the pressure chambers 31 and the air chambers 32 of the actuator base 11, respectively. The electrode layer 34 is formed of a conductive film such as a nickel thin film, for example. The electrode layer 34 extends from the inner surface portion of the groove 14 onto the substrate 21 and is connected to the pattern wiring 211. For example, the electrode layer 34 is formed on at least the side surface portion of the element wall 33, that is, the side wall surface of the groove 14 that constitutes the pressure chamber 31. The electrode layer 34 may be formed on the side surface portion and the bottom surface portion of the pressure chamber 31, for example.

[0023] The plurality of pressure chambers 31 communicate with the plurality of nozzles 28 of the nozzle plate 12 joined to the top 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 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. Therefore, ink flows in from one end of the pressure chamber 31 and flows out from the other end. A throttle portion 240 having a throttle port 242 configured to have a larger flow path resistance than the inside of the pressure chamber 31 is formed at the communication port of the pressure chamber 31 with the ink chamber 27. As an example, in the present embodiment, throttle portions 240 are formed at the communication ports at both ends in the extending direction of the pressure chamber 31, respectively.

[0024] As shown in Figures 4 and 5, the aperture portion 240 is configured to narrow the opening communicating with the ink chamber 27 of the pressure chamber 31 in the X direction. As an example, the aperture portion 240 has projections 241 and lid portions 243 as aperture walls made of photosensitive resin, and forms an aperture opening 242 which is a slit-shaped opening surrounded by these projections 241 and lid portions 243.

[0025] The projection 241 protrudes from the element wall 33 into the groove 14 at the second end of the pressure chamber 31. In this embodiment, projections 241 made of photosensitive resin are formed on each of the pair of element walls 33 that constitute both sides of the pressure chamber 31 in the X direction, i.e., on the element walls 33 on both sides in the X direction.

[0026] For example, the projection 241 may be formed along its entire length in the third direction, which is the depth direction of the groove 14 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 14 in addition to the side surface of the groove 14. That is, the projections 241 on both sides may be continuous at the bottom of the groove 14.

[0027] The cover portion 243 is provided at one end in the depth direction of the opening formed between the pair of protrusions 241, i.e., the end on the nozzle plate 12 side. The cover portion 243 is a wall-like member that covers the nozzle plate 12 side of the nozzle opening 242 and prevents the adhesive 29 applied to the nozzle plate 12 during joining from entering the nozzle opening 242. For example, the cover portion 243 is a wall-like member made of photosensitive resin and having a predetermined thickness in the Z direction. For example, the cover portion 243 is formed in a region including the area between the nozzle opening 242 and the nozzle plate 12, as shown in Figure 5, and closes the opening of the nozzle opening 242 on the nozzle plate 12 side. For example, the cover portion 243 may be formed in a region including the peripheral part of the nozzle opening 242. Furthermore, the lid portion 243 only needs to be configured to narrow the opening of the nozzle plate 12 side of the suction opening 242 and suppress the inflow of the adhesive 29. Depending on conditions such as the viscosity of the adhesive 29, it may also have a gap in a part of it.

[0028] The groove 14 constituting the pressure chamber 31 is not completely covered by the projection 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 31, and its opening width in the first direction is set to be smaller than the width of the inside of the pressure chamber 31 in the first direction, so that it is set to be smaller than the flow path cross-sectional area of ​​the pressure chamber 31. In other words, the projection 241 partially blocks the communication openings at both ends in the second direction, forming a throttling section 240 that increases the flow path resistance.

[0029] For example, the aperture portion 240 is formed by first forming a photosensitive resin film 244 on the inner walls of the pressure chamber 31 and the air chamber 32, and then curing the portion constituting the projection 241 and the portion constituting the lid 243 by two exposure processes with different exposure conditions.

[0030] Furthermore, if the flow 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 that corresponds 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. For example, the projections 241 provided on both sides of each communication opening of the pressure chamber 31 are each configured with a rectangular cross-section perpendicular to the third direction, and have a uniform cross-sectional shape in the third direction.

[0031] The air chamber 32 is sealed by a nozzle plate 12, which is joined to the top of one side in the third direction. Furthermore, multiple air chambers 32 are sealed by cover portions 23, for example, both ends in the second direction, which are made of a photosensitive resin material. 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 and the second common chamber 272, 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 cannot 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 portion in the same or a different process as when the protrusion portion 241 was formed.

[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 a drive IC 52 connected to the multiple wirings of the film 51. The drive IC 52 is electrically connected to the electrode layer 34 via the wirings and pattern wirings 211 of the film 51.

[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, the drive 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 that forms multiple grooves 14 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 14 that constitute 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, the method for forming the aperture portion 240 includes a film formation process in which a film of photosensitive resin is formed in the groove 14 that constitutes the pressure chamber 31, and a molding process in which the film is formed by exposure and development.

[0045] As part of the film formation process, first, as shown in Act 11 of Figure 6, a photosensitive resin is applied to the inner wall of the pressure chamber 31 to form a photosensitive resin film 244.

[0046] Next, as a molding process, the photosensitive resin film 244 at both ends of the pressure chamber 31 is formed by exposure and development processes. For example, in this embodiment, as an example, the portion 2441 constituting the projection 241 and the portion 2443 constituting the lid 243 are hardened by two exposure processes under different exposure conditions, and then a development process is performed to form the aperture portion 240 having the projection 241 and the lid 243.

[0047] In each exposure process of the molding process, a photomask having a pattern that hardens the area where the resin film is to be formed is placed on top as needed, and ultraviolet light is irradiated onto it. Conditions such as the exposure direction and exposure intensity are set as appropriate. For example, as the first exposure process, as shown in Act 11, an exposure mask 245 is placed on the top side of the element wall 33, and exposure is performed from the top side through the exposure mask 245 to expose to a depth reaching the bottom of the groove 14, thereby hardening the photosensitive resin film 244 of the portion 2441 that constitutes the protrusion 241. As an example, by setting the exposure direction in the depth direction of the pressure chamber 31, both protrusions 241 can be exposed and molded simultaneously.

[0048] Subsequently, as shown in Act 12, a second exposure mask 246 having an opening pattern corresponding to a cured area wider than the opening end on the top side of the aperture 242 is placed on the top side of the actuator base 11 element wall 33, and a second exposure is performed to cure the region including the part 2443 corresponding to the lid 243. That is, only the part 2442 corresponding to the aperture 242 remains uncured. The exposure depth of the second exposure process is shallower than the first exposure depth and is set to an exposure depth corresponding to the thickness of the lid 243. Alternatively, the exposure depth and cured area may be set by setting the exposure direction oblique to the depth direction of the groove 14, or exposure may be performed without using the exposure mask 246, for example. After that, by washing away the unnecessary unexposed resin with a developer, as shown in Act 13, an aperture portion 240 is formed at the inlet and outlet of the pressure chamber 31, with the aperture 242 opening due to the projection 241 and the lid 243.

[0049] As a result, a projection 241 and a cover portion 243 made of resin film are formed at the inlet and outlet of the pressure chamber 31, and a constricted portion 240 is formed between the projections 241 and the cover portion 243 on both sides.

[0050] Furthermore, during the film formation process and exposure and development process of the aperture portion 240, the cover portion 23 that closes the air chamber 32 may be formed simultaneously with the aperture portion 240 by simultaneously performing the film formation process and exposure and development process to apply photosensitive resin to both ends of the air chamber 32. Alternatively, the cover portion 23 may be formed in a separate process before or after the aperture portion 240 is formed.

[0051] 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.

[0052] Next, the assembled frame 13, the top 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 of the element wall 33, the frame 13, and the projection 241. For example, adhesive 29 is applied to the surface of the nozzle plate 12 facing the pressure chamber 31 to form an adhesive layer 291, the nozzle 28 is positioned to face it, and after being attached, the adhesive 29 is cured to bond it. At this time, since a cover portion 243 is formed on the nozzle plate 12 side, it is possible to prevent the uncured adhesive 29 from entering the nozzle opening 242. As a result, the nozzle plate 12 is bonded to the actuator section 22, and an adhesive layer 291 is provided between the element wall 33 and the cover portion 243 and the nozzle plate 12. Furthermore, as shown in Figure 1, the inkjet head 10 is completed by connecting the drive IC 52 and the circuit board 17 to the pattern wiring 211 formed on the main surface of the substrate 21 via a flexible printed circuit board.

[0053] An example of an inkjet printer 100 equipped with an inkjet head 10 will be described below with reference to Figure 7. 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] The media discharge unit 114 includes a paper output tray configured to hold the paper P discharged from the discharge port.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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 drive IC 52 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 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 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.

[0070] According to the embodiment described above, the formation of a throttling at the inlet and outlet of the pressure chamber 31 improves discharge stability. 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.

[0071] Furthermore, in the inkjet head 1, the structure is designed to fill the upper part of the slit-shaped aperture 242 of the aperture section 240 with a photosensitive resin, thereby suppressing the flow of adhesive 29 and improving productivity. That is, for example, when joining the nozzle plate 12 to the actuator section 22, if the aperture section 240 is filled with excess adhesive 29 flowing in, printing defects will occur and productivity will decrease, but the cover section 243 can prevent printing defects.

[0072] Furthermore, according to the above embodiment, a photosensitive resin film can be formed in the groove 14 of the actuator section 22 and patterned by exposure treatment to form the aperture section 240, which allows for the formation of the aperture section 240 with fewer steps, low cost, and ease. Moreover, since the thickness and shape of the protrusions 241 can be selected relatively freely by exposure and development, it is easy to freely design the flow resistance of the aperture. In addition, in the above embodiment, since the side surface 221 of the actuator section 22 constitutes an inclined surface, there are fewer constraints on the exposure direction, and exposure and development treatments are easier.

[0073] 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.

[0074] In the above embodiment, the lid portion 243 is shown to be formed in the region of the throttling opening 242, but it is not limited to this. For example, the lid portion 243 may be formed in a region including the parts of the pressure chamber 31 and air chamber 32 on the nozzle plate 12 side, or it may be formed in a position corresponding to the entire surface of the nozzle plate 12. Alternatively, it may be partially formed in some or more of these areas.

[0075] For example, if a cover portion 243 is to be formed in the area of ​​the nozzle plate 12 that includes the position of the nozzle 28, for example, the area that includes the upper surface of the pressure chamber 31, the nozzle plate 12 can be joined to the actuator portion 22, and then the nozzle plate 12 can be processed together with the cover portion 243 to form the nozzle 28.

[0076] 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.

[0077] Furthermore, the cover portion 23, projection portion 241, and lid portion 243 are formed inside the groove 14 that forms the pressure chamber 31 and air chamber 32, and are shaped to fill a part of the groove 14, but are not limited to this. For example, on the side surface of the actuator portion 22, the cover portion 23 that closes the air chamber 32, the projection portion 241 that partially closes the communication opening of the pressure chamber 31, and the lid portion 243 may be formed outside the groove 14 that forms the pressure chamber 31 and air chamber 32, and the throttling portion 240 may be formed outside the groove 14 and the element wall 33.

[0078] In the above embodiment, an example was shown in which an actuator unit 22 having a plurality of grooves 14 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.

[0079] 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.

[0080] 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, it is not limited to this. For example, it may be a non-circulating type. Alternatively, for example, the common chambers on both sides of the pressure chamber 31 may be the supply sides, and the fluid may flow in from both sides. That is, the fluid may flow in from both sides of the pressure chamber 31 and flow out from the 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, the flow resistance can be increased and the discharge efficiency can be improved. Also, the configuration of the throttling portions 240 formed at each end may be different.

[0081] 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 flow resistance compared to the inside of the pressure chamber 31 may be formed at one end, and the other end may have the same flow 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.

[0082] In the above embodiment, a side-shooter type in which both sides of the pressure chamber 31 communicate with the ink chamber was exemplified, 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.

[0083] 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.

[0084] The example shown illustrates the lid being formed by curing a photosensitive resin, but this is not the only option. For example, the lid 243 may be formed by heat-welding a film-like material such as a dry film resist.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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 section having multiple pressure chambers, A nozzle plate positioned opposite to the plurality of pressure chambers, A throttling section is provided at the communication port between the common chamber, which communicates with the pressure chamber, and the pressure chamber, forming a throttling opening that has greater flow resistance than the pressure chamber, and a lid portion is provided on the nozzle plate side of the throttling opening. A liquid dispensing head equipped with a liquid dispensing head. (2) The actuator portion comprises a plurality of side wall portions arranged in a first direction, and a plurality of grooves are formed between the plurality of side wall portions, forming the pressure chamber and opening toward the nozzle plate side, and the throttling portion is provided on the side wall portion and has a throttling wall that narrows the width dimension of the communication opening in the first direction to that of the inside of the pressure chamber in the first direction, An adhesive layer is provided between the side wall portion and the lid portion and the nozzle plate. (1) The liquid dispensing head described above. (3) The lid and the aperture wall are made of photosensitive resin. (2) The liquid dispensing head described above. (4) The actuator section has a plurality of air chambers, each formed between the plurality of pressure chambers. The pressure chamber and the air chamber are aligned in a first direction and extend in a second direction intersecting the first direction, A side-shooter type liquid discharge head according to (1), wherein the throttling portions are arranged at both ends of the pressure chamber in the second direction, and both ends of the pressure chamber communicate with the common chamber via the throttling ports. (5) The liquid discharge head according to (1), wherein the lid portion is formed on the nozzle plate side in an area including the nozzle opening and the area surrounding the nozzle opening. [Explanation of Symbols]

[0089] 10...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, 100...Inkjet printer, 111...Housing, 112...Media supply section, 113...Image forming section , 114...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, 240...Constriction section, 241...Protrusion, 242...Constriction opening, 243...Lid section, 271...First common chamber, 27...Ink chamber, 272...Second common chamber.

Claims

1. A liquid discharge head comprising: an actuator section having a plurality of pressure chambers; a nozzle plate positioned opposite the plurality of pressure chambers; and a throttling section provided at a communication port between a common chamber communicating with the pressure chambers and the pressure chambers, forming a throttling opening with greater flow resistance than the pressure chambers, and having a lid portion positioned on the nozzle plate side of the throttling opening, The actuator portion comprises a plurality of side wall portions arranged in a first direction, a plurality of grooves formed between the plurality of side wall portions that constitute the pressure chamber and open toward the nozzle plate side, the throttling portion is made of photosensitive resin and is positioned at the end of the groove in a second direction intersecting the first direction, and has a pair of protrusions that project into the groove from a pair of side wall portions that constitute both sides of the pressure chamber in the first direction, thereby narrowing the width dimension of the communication opening in the first direction to that of the pressure chamber in the first direction, and a lid portion provided at the nozzle plate side end of the opening formed between the pair of protrusions, which closes the nozzle plate side opening of the throttling portion, and has an adhesive layer between the side wall portions and the lid portion and the nozzle plate.

2. The actuator section has a plurality of air chambers, each formed between the plurality of pressure chambers. The pressure chamber and the air chamber are aligned in the first direction and extend in the second direction, A liquid discharge head according to claim 1, of the side-shooter type, wherein the throttling portions are arranged at both ends of the pressure chamber in the second direction, and both ends of the pressure chamber communicate with the common chamber via the throttling ports.

3. The liquid dispensing head according to claim 1, wherein the lid portion is formed on the nozzle plate side in an area including the nozzle opening and the area surrounding the nozzle opening.

Images