JP7689066B2 - Liquid ejection head - Google Patents

Description

An embodiment of the present invention relates to a liquid ejection head.

In recent years, high productivity has been required for inkjet heads, and higher speeds and increased droplet volume have become issues. For example, in a share-mode share-wall type inkjet head, the same drive column is shared by two pressure chambers, and so-called three-cycle drive is common, in which one-third of the multiple arranged chambers are driven simultaneously as pressure chambers. In addition, an independent drive head has been developed in which both sides of the driven pressure chamber are used as dummy pressure chambers and one pressure chamber is driven by two independent drive columns. For example, a structure has been developed in which many grooves are formed in a piezoelectric body, and the entrances and exits of every other groove are blocked, with the grooves whose entrances and exits are not blocked serving as pressure chambers and the blocked grooves serving as air chambers, and independent drive is achieved.

In such inkjet heads, the displacement vibrations that occur when driving a pressure chamber are transmitted through the wall that blocks the air chamber to the ink in an adjacent pressure chamber, causing crosstalk.

JP 2008-94036 A

The problem that this invention aims to solve is to provide a liquid ejection head that can ensure stable ejection characteristics.

A liquid ejection head according to one embodiment is made of a piezoelectric material and includes a plurality of side walls forming a plurality of grooves that alternately configure a plurality of pressure chambers and a plurality of air chambers, a first common chamber arranged at one end side of the extension direction of the plurality of pressure chambers, a second common chamber arranged at the other end side of the extension direction of the plurality of pressure chambers, a pair of extension walls extending in the extension direction of the air chamber from ends of a pair of the side walls that configure both sides of the air chamber, respectively, and a connecting wall that connects the extension walls outside the ends of the side walls and closes the ends of the grooves of the air chambers, and the pressure chambers communicate with a nozzle that ejects liquid droplets. One end side of the extension direction opens into the first common chamber, and the other end side of the extension direction opens into the second common chamber.

FIG. 1 is a perspective view showing an inkjet head according to an embodiment. FIG. 2 is an exploded perspective view showing a configuration of a portion of an inkjet head according to an embodiment. FIG. 3 is a partially enlarged perspective view of a main part of the inkjet head of FIG. 2 . FIG. 2 is an enlarged cross-sectional view showing a configuration of a portion of the inkjet head. 5 is a cross-sectional view of the inkjet head of FIG. 4 taken along line F5-F5. 6 is a cross-sectional view of the inkjet head of FIG. 4 taken along line F6-F6. 3 is a partially enlarged cross-sectional view of the inkjet head of FIG. 2 taken along line F7-F7; 5A and 5B are enlarged partial cross-sectional views for explaining the driving operation of the inkjet head according to the embodiment. 5A and 5B are explanatory diagrams of vibration states during driving in the inkjet head according to the first comparative example and the inkjet head according to the first comparative example. 4 is an explanatory diagram of crosstalk in the inkjet head according to the first embodiment and the inkjet head according to the first comparative example. 11A and 11B are explanatory diagrams of a vibration state during driving in the inkjet head according to Comparative Example 2. FIG. 1 is a schematic diagram showing an inkjet printer according to an embodiment.

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 Figs. 1 to 8. Fig. 1 is a perspective view showing the inkjet head according to the first embodiment, and Fig. 2 is an exploded perspective view of a part of the inkjet head. Fig. 3 is an enlarged perspective view showing a part of the configuration of the inkjet head, and Figs. 4 to 7 are enlarged cross-sectional views showing a part of the configuration of the inkjet head. Fig. 8 is an explanatory diagram of the driving state. In the figure, X, Y, and Z respectively indicate a first direction, a second direction, and a third direction that are perpendicular to each other. Note that in this embodiment, the directions are described based on the orientation in which the parallel direction of the nozzles 28 and pressure chambers 31 of the inkjet head 10 is along the X axis, the extension direction of the pressure chambers 31 is along the Y axis, and the ejection direction of the liquid is along the Z axis, but the present invention is not limited to this.

As shown in Figures 1 to 7, the inkjet head 10 is a so-called side shooter type share mode share wall type inkjet head. The inkjet head 10 is a device for ejecting ink, and is mounted inside an inkjet printer, for example. 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 chamber 32 is an air chamber to which ink is not supplied, and does not have a nozzle 28.

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 substrate. Inside the inkjet head 10, an ink chamber 27 is formed to which ink, an example of a liquid, is supplied.

The inkjet head 10 further 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.

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

The substrate 21 is formed in a rectangular plate shape from ceramics such as alumina. The substrate 21 has a flat mounting surface. A pair of actuators 22 are bonded to the mounting surface of the substrate. A plurality of supply holes 25 and discharge holes 26 are formed in the substrate 21.

As shown in Figures 2 and 3, a 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 a common pattern and an individual pattern, and is configured in a predetermined pattern shape that is connected to the electrode layer 34 formed on the actuator 22. For example, the pattern wiring 211 is formed at a position that avoids the supply hole 25 and the discharge hole 26.

The supply holes 25 are provided in the center of the substrate 21, between the pair of actuators 22, and aligned in the longitudinal direction of the actuators 22. The supply holes 25 communicate with the ink supply section of the manifold 18. The supply holes 25 are connected to an ink tank via the ink supply section. The supply holes 25 supply ink from the ink tank to the ink chambers 27.

The discharge holes 26 are arranged in two rows, sandwiching the supply holes 25 and the pair of actuators 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 into the ink tank.

The pair of actuators 22 are attached to the mounting surface of the substrate 21. The pair of actuators 22 are arranged in two rows on the substrate 21 with the supply hole 25 in between. Each actuator 22 is formed of two plate-shaped piezoelectric bodies made of lead zirconate titanate (PZT), for example. The two piezoelectric bodies are bonded together so that their polarization directions are opposite to each other in the thickness direction. The actuators 22 are attached to the mounting surface of the substrate 21, for example, with a thermosetting epoxy adhesive. As shown in FIG. 2, the actuators 22 are arranged in parallel in the ink chamber 27 corresponding to the two rows of nozzles 28. The actuators 22 divide 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 hole 26 opens.

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

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

As shown in Figures 2, 5, and 6, the bottom surface of the groove and the main surface of the substrate 21 are connected by an inclined side surface 221. The pressure chambers 31 and air chambers 32 are arranged alternately. The pressure chambers 31 and air chambers 32 each extend in a direction intersecting the longitudinal direction of the actuator 22, and are arranged in parallel in a first direction (X-axis in the figures) which is the longitudinal direction of the actuator 22. In this embodiment, for example, the width dimension of the groove 14 in the X direction is constant in the depth direction along the Z direction, and the cross section perpendicular to the Y direction which is the extension direction of the groove 14 is rectangular.

The shape of the pressure chamber 31 and the shape of the air chamber 32 may be different. The side 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 a drive signal.

An electrode layer 34 is provided on the inner wall surfaces of the pressure chamber 31 and air chamber 32 of the actuator base 11 and on the side surface 221. The electrode layer 34 is formed of a conductive film such as a nickel thin film. The electrode layer 34 runs from the inner surface of the groove through the side surface 221 onto the substrate 21 and is connected to the pattern wiring 211. For example, the electrode layer 34 is formed on at least one of the side surface and bottom surface of the side wall 33.

The multiple pressure chambers 31 communicate with multiple nozzles 28 of the nozzle plate 12 joined to the top. Both ends of the pressure chamber 31 in the second direction communicate with the ink chamber 27. That is, one end opens 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 ink flows out from the other end. Also, ink may flow in from both ends of the pressure chamber 31.

As shown in Figures 3 and 6, one side of the air chamber 32 in the third direction (Z direction) is blocked by the nozzle plate 12 joined to the top. In addition, both ends of the multiple air chambers 32 in the second direction are blocked by the cover portion 23, for example. That is, cover portions 23 are arranged between the first common chamber 271 of the ink chamber 27 and the air chamber 32, and between the air chamber 32 and the second common chamber 272, respectively, and both ends of the air chamber 32 are separated from the ink chamber 27. Therefore, the air chamber 32 constitutes an air chamber into which ink does not flow.

For example, the cover portion 23 is provided at both ends of each air chamber 32 in the Y direction, which is the extension direction of each air chamber 32. The cover portion 23 connects the ends of the side walls 33 to each other and has a partition portion 230 that separates the common chambers 271, 272 from the air chamber 32. For example, at least a portion of the partition portion 230 is disposed outside the side walls 33 in the extension direction of the air chamber 32.

The partition wall 230 is configured to suppress the transmission of displacement vibration of the side wall 33. The partition wall 230 includes a pair of extending walls 231 extending in the extension direction of the air chamber 32, and a connecting wall 232 connecting the pair of extending walls 231. An air layer 321 is interposed between the pair of extending walls 231. That is, the pair of extending walls 231 are spaced apart in the first direction (X direction) which is the deformation direction. The partition wall 230 has a bent portion, and connects the pair of side walls 33 in a detour at a connection distance longer than the distance between the pair of side walls 33. The partition wall 230 is elastically deformable and configured to absorb the displacement vibration of the side wall 33. That is, the partition wall 230 is configured such that the connection distance connecting the side walls 33 is longer than the connection distance of the end portions of the side walls 33 connected to each other at the shortest distance with a flat plate-shaped member. The length of the wall of the partition wall 230 is longer than the width dimension of the air chamber 32. The partition 230 is a wall-shaped member that passes outside the end of the side wall 33 in the extension direction of the air chamber 32, blocks the end of the air chamber 32, and has a bent portion that is U-shaped or C-shaped.

The pair of extending walls 231 are wall members that extend in the extending direction of the air chamber 32 from a pair of side walls 33 that form both sides of the target air chamber 32. The extending walls 231 form an elastic deformation portion that can be deformed by the displacement vibration of the side walls 33. An air layer 321 that connects to the air chamber 32 is interposed between the pair of extending walls 231. In other words, the pair of extending walls 231 expands the air chamber 32 outward beyond the ends of the side walls 33.

The connecting wall 232 connects the outer ends of the pair of extending walls 231 at a position away from the side walls 33. The connecting wall 232 is a wall member that extends in a direction perpendicular to the longitudinal direction of the air chamber 32 and in the direction in which the multiple grooves are arranged. The connecting wall 232 may be a flat wall member that is disposed outside the ends of the side walls 33, or may be a curved wall.

The partition 230 is also made of a material that is less hard than the piezoelectric material. For example, the partition 230 is made of a resin material that is softer than the side walls 33. As an example, the partition 230 is made of a photosensitive resin material. For example, the partition 230 is formed by applying a photosensitive resin to both ends of the air chamber 32, and then exposing the resin to light and curing it into the shape of the partition 230.

When the side wall 33 is displaced in the X direction, the partition wall 230 configured in this manner elastically deforms so that the extending walls 231 are displaced in the X direction, thereby absorbing the displacement vibration of the side wall 33 and suppressing the transmission of vibration from one side wall 33 to the other side wall 33. In other words, the presence of a pair of extending walls 231 spaced apart from each other in the X direction, which is the vibration direction of the side wall 33, can suppress the transmission of vibration of one side wall 33 to the other side wall 33.

The nozzle plate 12 is formed, for example, from a rectangular film made of polyimide. The nozzle plate 12 faces the mounting surface of the actuator base 11. The nozzle plate 12 has a plurality of nozzles 28 formed therein, which penetrate the nozzle plate 12 in the thickness direction.

The nozzles 28 are provided in the same number as the pressure chambers 31, and are arranged opposite each of the pressure chambers 31. The nozzles 28 are arranged in two rows along the first direction (X direction) corresponding to the pair of actuators 22. Each nozzle 28 is configured in a cylindrical shape with an axis extending in the third direction. For example, the nozzles 28 may have a constant diameter, or may have a shape that narrows toward the center or tip. The nozzles 28 are arranged opposite the midpoint of the pressure chambers 31 formed in the pair of actuators 22 in the extension direction, and each nozzle 28 is connected to the pressure chambers 31. The nozzles 28 are arranged at positions corresponding to between both ends of each pressure chamber 31, for example, one nozzle each in the longitudinal center.

The frame 13 is formed into 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 adhered to both the mounting surface of the actuator base 11 and the nozzle plate 12. In other words, the nozzle plate 12 is attached to the actuator base 11 via the frame 13.

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

The circuit board 17 shown in FIG. 1 is a film carrier package (FCP). The circuit board 17 has a flexible resin film 51 on which multiple wirings are formed, and a driving IC 52 connected to the multiple wirings of the film 51. The driving IC 52 is electrically connected to the electrode layer 34 via the wirings of the film 51 and the pattern wiring 211.

Inside the inkjet head 10 configured as 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 (Y direction) by the two actuators 22, and has two second common chambers 272 as common chambers into which the discharge holes 26 open, and a first common chamber 271 as common chamber into which the supply hole 25 opens. The first common chamber 271 and the second common chamber 272 are connected to a plurality of pressure chambers 31.

Figure 7 is an enlarged cross-sectional view of the inkjet head 10 of Figure 2 cut longitudinally along F7-F7. Figure 8 is an enlarged cross-sectional view showing an example of the state in which the side wall 33 of Figure 7 has been deformed in a shear mode.

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

As shown by the solid line in FIG. 8, when the side 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. This causes ink in the ink chamber 27 to flow into the pressure chamber 31.

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

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

Next, the electrode layer 34 and the pattern wiring 211 are formed on the inner surfaces of the grooves that form the pressure chamber 31 and the air chamber 32 and on the surface of the substrate 21. As a result, the electrode layer 34 and the pattern wiring 211 are formed in predetermined locations on the surface of the actuator base 11.

Next, cover portions 23 are formed at the ends of air chamber 32 to close both ends of air chamber 32. For example, photosensitive resin is filled into the groove that constitutes air chamber 32, and the target area of the detour shape is hardened to form cover portion 23. Alternatively, after hardening the photosensitive resin, the area that will become air layer 321 is removed to form slit-shaped air layer 321, and the photosensitive resin layer is molded into a U-shape to form cover portion 23.

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.

The assembled frame 13, the top of the side wall 33 of the actuator 22, and the surface of the protrusion 241 facing the nozzle plate 12 are polished to be flush with each other. The nozzle plate 12 is then attached by gluing to the polished surface of the top of the side wall 33, the frame 13, and the protrusion 241. At this time, the nozzle 28 is positioned so that it faces the pressure chamber 31. Furthermore, as shown in FIG. 1, the driving IC 52 and the circuit board 17 are connected to the pattern wiring 211 formed on the main surface of the substrate 21 via a flexible printed circuit board, thereby completing the inkjet head 10.

Below, an example of an inkjet printer 100 equipped with an inkjet head 10 will be described with reference to FIG. 12. The inkjet printer 100 includes a housing 111, a medium supply unit 112, an image forming unit 113, a medium discharge unit 114, a conveying device 115, and a control unit 116.

The inkjet printer 100 is a liquid ejection device that ejects liquid such as ink onto a recording medium, such as paper P, while transporting the recording medium, such as paper P, along a predetermined transport path A that runs from the medium supply unit 112 through the image forming unit 113 to the medium ejection unit 114, thereby forming an image on the paper P.

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

The media supply unit 112 is equipped with multiple paper feed cassettes and is configured to hold multiple stacks of paper P of various sizes.

The medium discharge unit 114 is equipped with a paper discharge tray configured to hold the paper P discharged from the discharge port.

The image forming unit 113 includes a support unit 117 that supports the paper P, and a number of head units 130 that are arranged opposite each other above the support unit 117.

The support section 117 includes a conveyor belt 118 that is looped in a predetermined area where image formation is performed, a support plate 119 that supports the conveyor belt 118 from the back side, and a number of belt rollers 120 that are provided on the back side of the conveyor belt 118.

During image formation, the support section 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 feeding the conveyor belt 118 at a predetermined timing by rotating the belt roller 120.

The head unit 130 includes multiple (four colors) inkjet heads 10, ink tanks 132 as liquid tanks mounted on each inkjet head 10, a connection flow path 133 connecting the inkjet heads 10 and the ink tanks 132, and a circulation pump 134 as a circulation unit. The head unit 130 is a circulation type head unit that constantly circulates liquid in the ink tanks 132 and the pressure chambers 31, air chambers 32, and ink chambers 27 built inside the inkjet heads 10.

In this embodiment, the inkjet head 10 has four colors, cyan, magenta, yellow, and black, and ink tanks 132 that contain ink of each color. The ink tanks 132 are connected to the inkjet head 10 by a connection flow path 133. The connection flow path 133 has a supply flow path that is connected to the supply port of the inkjet head 10, and a recovery flow path that is connected to the discharge port of the inkjet head 10.

The ink tank 132 is also connected to a negative pressure control device such as a pump (not shown). 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, causing the ink supplied to each nozzle 28 of the inkjet head 10 to form a meniscus of a predetermined shape.

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

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

Each of the multiple guide plate pairs 121 has a pair of plate members arranged opposite each other with the paper P being transported therebetween, and guides the paper P along the transport path A.

The conveying rollers 122 are driven to rotate under the control of the control unit 116, thereby sending the paper P downstream along the conveying path A. Sensors that detect the conveying status of the paper are placed at various points along the conveying path A.

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

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

According to the above-mentioned embodiment, so-called crosstalk can be suppressed, and it is easy to maintain the ejection performance. According to the above-mentioned embodiment, the transmission of the displacement vibration between the multiple side walls 33 can be suppressed by blocking with the partition part 230 having a pair of extension walls 231 extending in the direction of the air chamber 32. For example, the extension wall 231 of the partition part 230 extending in the extension direction of the air chamber 32 is elastically deformed, and the displacement vibration can be damped. Therefore, the displacement vibration of the side wall 33 when driving the pressure chamber 31 in the actuator 22 is transmitted to the ink in another adjacent pressure chamber 31, which affects the pressure of the ink in the pressure chamber, so-called crosstalk can be suppressed, and the ejection performance can be easily maintained. In addition, the partition part 230 that connects the side walls 33 with a connection distance longer than the straight-line distance between the ends of the multiple side walls 33 increases the effect of damping the vibration within the partition part 230, and the transmission of the displacement vibration can be suppressed.

9 is an explanatory diagram showing the state of vibration of the side walls 33 during driving for the inkjet head 10 according to the present embodiment and the inkjet head 1010 according to the comparative example 1. As shown in FIG. 9, the inkjet head 1010 according to the comparative example 1 has a configuration in which the side walls 33 are connected at the shortest distance by a flat cover part 123. The cover part 123 of the inkjet head 1010 does not deform when the side walls 33 are displaced and vibrated. Therefore, in the inkjet head 1010, the displacement vibration of the side walls 33 when the pressure chamber 31 is driven is propagated inside the cover part 123, and the displacement vibration is transmitted to the adjacent side walls 33, which tends to cause crosstalk that affects the pressure of the ink in another adjacent pressure chamber 31. On the other hand, in the inkjet head 10, when the side walls 33 are displaced and vibrated, the extension wall 231 is elastically deformed, so that the displacement vibration can be attenuated. Therefore, crosstalk can be suppressed.

Figure 10 is a graph showing the relationship between crosstalk and the Young's modulus of the partition, the position of the partition, and the length of the extension wall 231 where the partition extends outward from the side wall 33. The configuration of the inkjet head 10 of this embodiment corresponds to a value greater than 0 μm in Figure 10, and it can be seen that the further outward the partition is positioned in the groove (the longer the extension wall 231), the more crosstalk can be reduced. The configuration of the inkjet head 1010 of Comparative Example 1 corresponds to the 0 μm position in Figure 10.

The inkjet head 2010 according to Comparative Example 2 shown in FIG. 11 corresponds to the position of less than 0 μm (negative value) in FIG. 10, and has a configuration in which the cover portion 123 is also formed inside the groove of the air chamber 32. The longer the length of the cover portion 123 formed inside the groove of the air chamber 32, the more easily the displacement vibration of the side wall 33 is transmitted to the adjacent side wall 33 via the cover portion 123 inside the groove of the air chamber 32, and the effect of crosstalk becomes greater. In the inkjet head 10 according to this embodiment, the partition portion 230 protrudes outward from the groove, and the extending wall 231 mitigates the displacement vibration of the side wall 33 by elastic deformation, thereby reducing crosstalk more than the inkjet heads of Comparative Examples 1 and 2.

In other words, in the inkjet head 10 according to this embodiment, the partition 230 has an extending wall 231 and a connecting wall 232, and since the partition 230 has an elastically deformable shape, when the side wall 33 undergoes displacement vibration, the displacement vibration of the side wall 33 is reduced, thereby suppressing the transmission of vibration to adjacent pressure chambers. Furthermore, in the inkjet head 10, the connection distance between adjacent side walls 33 of the partition 230 is long, which increases the effect of attenuating the displacement vibration within the partition 230. In addition, in the inkjet head 10, the partition 230 is made of a resin material that is softer than the piezoelectric member, thereby achieving the effect of attenuating vibration.

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

For example, the partition wall 230 has a bent portion and is configured with a protruding wall and an extending wall, but this is not limited to this. For example, the partition wall 230 may have a curved portion that is curved in a U-shape.

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

In the above embodiment, the actuator base 11 is provided with a laminated piezoelectric body made of a piezoelectric member 131 on a substrate 21, but the present invention is not limited to this. For example, the actuator base 11 may be formed only from a piezoelectric member without using a substrate. Also, instead of using two piezoelectric members, a single piezoelectric member may be used. The supply side and discharge side may be reversed, or may be configured to be switchable.

In addition, in the above embodiment, as an example, a circulation type inkjet head is exemplified in which one side of the pressure chamber 31 is the supply side and the other side is the discharge side, and the first common chamber fluid flows in from one side of the pressure chamber and flows out from the other side, but this is not limited to this. For example, a non-circulation type is also possible. Also, for example, the common chambers on both sides of the pressure chamber 31 may be the supply side, and the fluid may flow in from both sides. In other words, 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. Also, the shapes of the cover parts 23 formed on both ends may be different from each other.

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

In addition, in the above embodiment, the inkjet head is used in a liquid ejection device such as an inkjet printer, but the invention is not limited to this and can also be used in, for example, 3D printers, industrial manufacturing machines, and medical applications, allowing for reductions in size, weight, and cost.

At least one of the embodiments described above can provide a liquid ejection head and a method for manufacturing a liquid ejection head that can ensure stable ejection characteristics.

Although several other embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and their equivalents. Below, descriptions equivalent to the invention described in the claims at the time of the initial filing of this application are added.
(1)
a plurality of side walls formed of a piezoelectric material and forming a plurality of grooves that alternately define a plurality of pressure chambers and a plurality of air chambers;
a pair of extending walls extending in an extending direction of the air chamber from ends of the pair of side walls constituting both sides of the air chamber, and a connecting wall connecting the extending walls outside the ends of the side walls, and a partition wall portion closing an end of a groove of the air chamber,
The pressure chamber of the liquid ejection head communicates with a nozzle that ejects liquid droplets.
(2)
The liquid ejection head according to (1), wherein the extension wall extends in a direction perpendicular to a vibration direction of the side wall.
(3)
The partition wall has a bent portion,
The pair of extending walls are spaced apart from each other,
The liquid ejection head according to (1) or (2), wherein the connecting wall connects the pair of extending walls at a position spaced apart from the side walls.
(4)
The liquid ejection head according to any one of (1) to (3), wherein the partition portion is made of a material having a lower hardness than the piezoelectric material.
(5)
The liquid ejection head according to any one of (1) to (4), wherein the partition portion is made of a photosensitive resin material.

10...inkjet head, 11...actuator base, 12...nozzle plate, 13...frame, 17...circuit board, 18...manifold, 21...substrate, 22...actuator, 23...cover portion, 230...partition portion, 231...extension wall, 232...connection wall, 321...air layer, 25...supply hole, 26...discharge hole, 27...ink chamber, 31...pressure chamber, 32...air chamber, 33...side wall, 34...electrode layer, 51...film, 52...driving IC, 100...inkjet printer , 111...housing, 112...medium supply section, 113...image forming section, 114...medium discharge section, 115...conveyor device, 116...control section, 117...support section, 118...conveyor belt, 119...support plate, 120...belt roller, 121...pair of guide plates, 122...conveyor roller, 130...head unit, 132...ink tank, 133...connection flow path, 134...circulation pump, 211...pattern wiring, 221...side section, 271...first common chamber, 272...second common chamber.

Claims (5)

a plurality of side walls formed of a piezoelectric material and forming a plurality of grooves that alternately define a plurality of pressure chambers and a plurality of air chambers;
a first common chamber disposed on one end side of the extension direction of the plurality of pressure chambers;
a second common chamber disposed on the other end side in the extension direction of the plurality of pressure chambers;
a pair of extending walls extending in an extending direction of the air chamber from ends of the pair of side walls constituting both sides of the air chamber, and a connecting wall connecting the extending walls outside the ends of the side walls, and a partition wall portion closing an end of a groove of the air chamber,
the pressure chamber communicates with a nozzle that ejects droplets, one end side in the extension direction opens into the first common chamber, and the other end side in the extension direction opens into the second common chamber;
Liquid ejection head. The liquid ejection head according to claim 1, wherein the extension wall extends in a direction perpendicular to the vibration direction of the side wall. The partition wall has a bent portion,
The pair of extending walls are spaced apart from each other,
The liquid ejection head according to claim 1 , wherein the connecting wall connects the pair of extending walls at a position spaced apart from the side walls. The liquid ejection head according to any one of claims 1 to 3, wherein the partition is made of a material that is lower in hardness than the piezoelectric material. The liquid ejection head according to any one of claims 1 to 4, wherein the partition portion is made of a photosensitive resin material.