Liquid ejecting head

Abstract

The invention provides a liquid ejection head capable of applying a driving voltage for driving each piezoelectric actuator to a comb-shaped laminated piezoelectric block in which a plurality of piezoelectric actuators are disposed. According to one embodiment, a liquid ejection head includes a laminated piezoelectric block, a pressure chamber, a substrate, a flexible substrate, and a wiring electrode of the substrate. The laminated piezoelectric body block has a comb tooth shape in which a plurality of piezoelectric actuators and pillars are alternately arranged. The pressure chamber joins a part of a partition wall to an end surface of the piezoelectric actuator. The substrate is bonded to the surface of the base end side of the laminated piezoelectric body block. The flexible substrate is connected to the outer peripheral portion of the substrate. A wiring electrode of the substrate is connected to an external electrode of the piezoelectric actuator and is connected to a wiring of the flexible substrate at an outer peripheral portion of the substrate, and an electrode width at a connection portion of the substrate and the flexible substrate is equal to or greater than a pillar width of the piezoelectric actuator.

Description

Technical Field

[0001] An embodiment of the present invention relates to a liquid ejection head. Background Art

[0002] There is known a liquid ejection head that supplies a specified amount of liquid to a specified position. The liquid ejection head is mounted on, for example, an inkjet printer, a 3D printer, a dispensing device, etc. An inkjet printer ejects droplets of ink from an inkjet head to form an image on the surface of a recording medium. A 3D printer ejects droplets of a modeling material from a modeling material ejection head and solidifies the droplets to form a three-dimensional modeling object. A dispensing device ejects droplets of a sample and supplies a specified amount to a plurality of containers, etc.

[0003] The liquid ejection head has a plurality of channels for ejecting liquid. Each channel has a nozzle for ejecting liquid, a pressure chamber connected to the nozzle, and a piezoelectric actuator for changing the volume of the pressure chamber. The liquid ejection head selects a channel for ejecting liquid from the plurality of channels, applies a driving voltage to the piezoelectric actuator of the selected channel, and ejects the liquid. However, when the piezoelectric actuators of the plurality of channels are integrally formed using, for example, a comb-shaped stacked piezoelectric block, and a flexible substrate to which the driving voltage is applied is directly connected to the stacked piezoelectric block, the stacked piezoelectric block is easily damaged.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2009-208234

[0007] Patent Document 2: Japanese Patent Application Publication No. 2016-137589

[0008] Patent Document 3: Japanese Patent Application Publication No. 2011-5774 Summary of the invention

[0009] Technical problem to be solved by the invention

[0010] The technical problem to be solved by the present invention is to provide a liquid ejection head capable of applying a driving voltage for driving each piezoelectric actuator to a comb-shaped stacked piezoelectric body block in which a plurality of piezoelectric actuators are arranged.

[0011] Technical solutions to solve problems

[0012] The liquid ejection head of the embodiment of the present invention comprises a stacked piezoelectric block, a pressure chamber, a substrate, a flexible substrate, and a wiring electrode of the substrate. The stacked piezoelectric block is a comb-shaped structure in which a plurality of piezoelectric actuators and pillars are alternately arranged. The pressure chamber joins a portion of a partition wall to an end face of the piezoelectric actuator. The substrate joins to a surface on the base end side of the stacked piezoelectric block. The flexible substrate is connected to the outer periphery of the substrate. The wiring electrode of the substrate is connected to an external electrode of the piezoelectric actuator and is connected to the wiring of the flexible substrate at the outer periphery of the substrate, and the electrode width at the connection portion between the substrate and the flexible substrate is greater than the column width of the piezoelectric actuator. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a diagram showing the overall structure of an inkjet printer including the inkjet head according to the embodiment.

[0014] Figure 2 It is a perspective view of the above-mentioned inkjet head.

[0015] Figure 3 This is a cross-sectional view of a partially enlarged portion of the head portion of the inkjet head.

[0016] Figure 4 This is a cross-sectional view of a partially enlarged portion of the head portion of the inkjet head.

[0017] Figure 5 It is a top view which enlarges a part of the head part of the said inkjet head.

[0018] Figure 6 1 is a top view of the actuator substrate of the head.

[0019] Figure 7 It is a top view of a part of the actuator substrate which is enlarged.

[0020] Figure 8 It is a partially enlarged perspective view of the actuator substrate.

[0021] Fig. 9 It is a partially enlarged perspective view of the actuator substrate.

[0022] Fig.10 It is a partially enlarged perspective view of the actuator substrate.

[0023] Fig.11 It is a figure explaining the assembly process of the said inkjet head.

[0024] Fig.12 This is an assembly diagram of the inkjet head.

[0025] Fig.13 It is a circuit diagram of the control system of the above-mentioned inkjet head.

[0026] Fig.14 This is a driving waveform applied to the actuator of the inkjet head.

[0027] Fig.15 This is a diagram for explaining the operation of the above-mentioned actuator.

[0028] Description of Reference Numerals

[0029] 10: inkjet printer, 100-103: inkjet head, 2: head, 24: nozzle, 3: driver IC, 47: substrate, 6: actuator, 60: support, 64: individual electrode, 65: common electrode, 66: individual wiring, 67: common wiring, 600: stacked piezoelectric block, 604: extension part. DETAILED DESCRIPTION

[0030] Hereinafter, the liquid ejection head according to the embodiment will be described in detail with reference to the accompanying drawings. In addition, in each figure, the same reference numerals are given to the same structure. In addition, in order to clarify the orientation of the structure shown in each figure, XYZ coordinates are recorded in each figure.

[0031] As an example of an image forming apparatus equipped with the liquid ejection head according to the embodiment, an inkjet printer 10 that prints an image on a recording medium will be described. Figure 1 1 shows a schematic configuration of an inkjet printer 10. The inkjet printer 10 is provided inside a housing 11 with: a cassette 12 for storing a sheet S as an example of a recording medium, an upstream conveying path 13 for the sheet S, a conveyor belt 14 for conveying the sheet S taken out from the cassette 12, a plurality of inkjet heads 100 to 103 for ejecting ink droplets toward the sheet S on the conveyor belt 14, a downstream conveying path 15 for the sheet S, a discharge tray 16, and a control board 17. An operation unit 18 as a user interface is provided on the upper side of the housing 11.

[0032] Image data to be printed on the sheet S is generated by, for example, a computer 200 as an externally connected device. The image data generated by the computer 200 is sent to the control board 17 of the inkjet printer 10 via the cable 201 and the connectors 202 and 203 .

[0033] The pickup roller 204 feeds the sheets S one by one from the cassette 12 to the upstream conveying path 13. The upstream conveying path 13 is composed of a feed roller pair 131, 132 and sheet guide plates 133, 134. The sheet S is conveyed to the upper surface of the conveyor belt 14 via the upstream conveying path 13. The arrow 104 in the figure indicates the conveying path of the sheet S from the cassette 12 to the conveyor belt 14.

[0034] The conveyor belt 14 is an endless belt with a mesh having a plurality of through holes formed on the surface. The three rollers, namely, the driving roller 141, the driven rollers 142 and 143, support the conveyor belt 14 rotatably. The motor 205 rotates the conveyor belt 14 by rotating the driving roller 141. The motor 205 is an example of a driving device. 105 in the figure indicates the rotation direction of the conveyor belt 14. A negative pressure container 206 is arranged on the back side of the conveyor belt 14. The negative pressure container 206 is connected to a fan 207 for decompression. The fan 207 creates a negative pressure in the negative pressure container 206 through the airflow formed, thereby adsorbing and holding the sheet S on the upper surface of the conveyor belt 14. 106 in the figure indicates the flow direction of the airflow.

[0035] The inkjet heads 100 to 103 as an example of a liquid ejection head are arranged opposite to the sheet S held by adsorption on the conveyor belt 14, for example, with a small gap of 1 mm therebetween. The inkjet heads 100 to 103 eject ink droplets in the -Z direction toward the sheet S transported from the -Y direction to the Y direction. The inkjet heads 100 to 103 print an image when the sheet S passes from below. The structures of the inkjet heads 100 to 103 are the same except that the colors of the ejected inks are different. The colors of the inks are, for example, cyan, magenta, yellow, and black.

[0036] The inkjet heads 100 to 103 are connected to ink tanks 315 to 318 and ink supply pressure adjustment devices 321 to 324 via ink flow paths 311 to 314, respectively. Each ink tank 315 to 318 is arranged above each inkjet head 100 to 103. When on standby, each ink supply pressure adjustment device 321 to 324 adjusts the pressure inside each inkjet head 100 to 103 to a negative pressure, for example -1.2 kPa, relative to the atmospheric pressure to prevent the ink from flowing out of the nozzles 24 (see Figure 2 When forming an image, the ink in each ink tank 315 to 318 is supplied to each inkjet head 100 to 103 through the ink supply pressure adjustment device 321 to 324.

[0037] After the image is formed, the sheet S is conveyed from the conveyor belt 14 toward the downstream conveying path 15. The downstream conveying path 15 is composed of feed roller pairs 151, 152, 153, 154 and sheet guide plates 155, 156 that define the conveying path of the sheet S. The sheet S is conveyed from the discharge port 157 to the discharge tray 16 via the downstream conveying path 15. The arrow 107 in the figure indicates the conveying path of the sheet S.

[0038] Next, the structure of the inkjet heads 100 to 103 will be described. Figures 2 to 10 The inkjet head 100 will be described. The structures of the inkjet heads 101 to 103 are also the same as that of the inkjet head 100 .

[0039] like Figure 2As shown in FIG. 1 , the inkjet head 100 includes a head portion 2 as an example of a liquid ejecting portion. The head portion 2 is connected to the inkjet head 100 via an ink flow path 311. Figure 1 The ink supply pressure regulating device 321 is connected. In the case of circulating ink supply, the ink supply path and the discharge path are connected to the head 2. The nozzles 24 of each ejection channel that ejects ink are arranged along the first direction of the nozzle plate 23, for example, the X direction. The nozzle density is set in the range of 150dpi to 1200dpi, for example. The nozzles 24 are arranged in two columns, column A on the Y direction side and column B on the -Y direction side. For example, when the number of ejection channels is 656, column A arranges nozzles No. 1 to No. 328 in sequence from the X direction to the -X direction, and column B arranges nozzles No. 1 to No. 328 in sequence from the -X direction to the X direction. However, the nozzles 24 can be either one column or three or more columns. In addition, as described above, the sheet S is transported from the -Y direction to the Y direction, and the ink is ejected in the -Z direction toward the surface of the sheet S located below the nozzle 24.

[0040] The head 2 is connected to a flexible printed wiring board 21 as an example of a flexible substrate. The flexible printed wiring board 21 is connected to a printed circuit board 22 as an example of a relay substrate. The flexible printed wiring board 21 and the printed circuit board 22 are connected to the head 2 symmetrically in two groups, for example, for column A and column B.

[0041] The flexible printed wiring board 21 is a flexible printed wiring substrate using a synthetic resin film such as polyimide. The flexible printed wiring board 21 is equipped with a driving IC (Integrated Circuit) 3 (hereinafter referred to as a driving IC) as a driving chip. The printed substrate 22 is a hard through-hole substrate formed by stacking epoxy resin layers containing glass fibers and copper wiring layers. The driving IC 3, which is the control unit of the inkjet head 100, temporarily stores data sent from the control substrate 17 via the printed substrate 22, and applies a driving signal to each channel at a specified timing to eject ink, wherein the control substrate 17 has a CPU as the control unit of the inkjet printer 10.

[0042] Figures 3 to 5 It is a partial cross-sectional view of the head 2. Figure 4 yes Figure 3 A cross-sectional view of CC, Figure 5 yes Figure 3 DD is a cross-sectional view of FIG. In addition, the ejection channels of column A and column B are symmetrically arranged back to back with the center line of the X direction interposed therebetween. Therefore, in the following description, there are places where only the ejection channels of column A are illustrated and described, but the structure of the ejection channels of column B is the same.

[0043] The nozzle plate 23 is bonded to one side of the pressure chamber substrate 4. The nozzle plate 23 is a rectangular plate formed of, for example, a resin such as polyimide or a metal such as stainless steel. The vibration plate 5 is bonded to one side of the pressure chamber substrate 4 on the opposite side of the nozzle plate 23. The vibration plate 5 has flexibility to deform when an external force is applied. The vibration plate 5 is, for example, a thin plate formed of a metal such as nickel or stainless steel. The material of the vibration plate 5 may also be a material other than metal such as a polyimide film.

[0044] The pressure chamber 42 is formed on the pressure chamber substrate 4. The pressure chambers 42 of each ejection channel are arranged at the position of each nozzle 24 and are respectively connected to the nozzle 24. The pressure chamber substrate 4 is formed of a metal such as stainless steel. As an example, the pressure chamber 42 is formed by forming a rectangular opening penetrating along the second direction, such as the Z direction, on the pressure chamber substrate 4, and blocking the openings on both sides with the nozzle plate 23 and the vibration plate 5. That is, the vibration plate 5 constitutes a part of the partition wall of the pressure chamber 42.

[0045] The pressure chamber 42 is connected to the guide flow path 43 having a narrow portion, and further connected to the ink supply manifold 45 via the ink supply port 44 which is an opening hole penetrating the vibration plate 5. The guide flow path 43 is formed in a groove shape along a third direction, for example, the Y direction, on one surface of the pressure chamber substrate 4 on the vibration plate 5 side for each pressure chamber 42. The nozzle 24, the pressure chamber 42, and the guide flow path 43 are provided in each ejection channel. The ink supply port 44 is shared by the ejection channels of the back-to-back A column and the B column.

[0046] The ink supply manifold 45 is formed in a frame 46 joined to one surface of the vibration plate 5. The ink supply manifold 45 extends in the X direction and communicates with the pressure chamber 42 of each channel via the ink supply port 44 and the guide flow path 43 of each channel. The ink supply manifold 45 as a common ink chamber communicates with the ink flow path 311 (see Figure 1 , Figure 2 ). Ink ports 48 and ink ports 49 are provided at both ends of the frame 46 in the X direction and the -X direction. The ink ports 48 and the ink ports 49 can also be used for supplying and discharging ink when filling ink (see Fig.12 ).

[0047] The actuators 6 of each ejection channel are arranged at positions opposite to the pressure chambers 42 of each ejection channel via the vibration plate 5. The end faces of the actuators 6 of each ejection channel in the -Z direction are bonded to the vibration plate 5 constituting a part of the partition wall of the pressure chamber 42, for example, by an adhesive. The actuator 6, which is an example of a piezoelectric actuator, is a stacked piezoelectric actuator (see in particular FIG. 1 ) in which a piezoelectric body 61 such as a piezoelectric element, a first internal electrode 62, and a second internal electrode 63 are alternately stacked in layers. Figure 3). Each piezoelectric body 61 is configured so that the polarization directions are opposite to each other, for example, in the Z direction, and deforms in the d33 mode. The piezoelectric body 61 is formed of a lead-containing piezoelectric material such as lead zirconate titanate (PZT) or a lead-free piezoelectric material such as sodium potassium niobate.

[0048] The first internal electrode 62 and the second internal electrode 63 are conductive films formed on the main surface of the piezoelectric body 61, respectively. The first internal electrode 62 and the second internal electrode 63 are formed of a conductive material that can be fired, such as silver palladium. In the case of column A, the first internal electrode 62 of the actuator 6 is formed on one side of the actuator 6 in the Y direction, and is connected to a separate electrode 64 formed on the side as an external electrode. The second internal electrode 63 is formed on the other side of the actuator 6 in the -Y direction, and is connected to a common electrode 65 formed on the side as an external electrode. The virtual layer 68 is made of the same material as the piezoelectric body 61. However, the virtual layer 68 is not provided with an internal electrode, and an electric field is not applied, so it does not deform.

[0049] The side surface of the actuator 6 forming the individual electrode 64 is inclined outward from the end surface connected to the vibration plate 5 toward the substrate 47. The inclination angle θ is, for example, 45 degrees to 80 degrees. On the other hand, the side surface of the actuator 6 forming the common electrode 65 is set to an inclination angle greater than θ, or is not inclined but stands vertically relative to the surface of the substrate 47. The individual electrode 64 and the common electrode 65 are formed of, for example, Ni, Cr, Au, etc.

[0050] Especially if Figure 4 As shown, the support 60 is arranged between the actuators 6 of each ejection channel via the groove 69. The support 60 is arranged at a position corresponding to the partition wall 40 between the adjacent pressure chambers 42. The driving actuator 6 and the dummy actuator as the support 60 are formed uniformly using a common piezoelectric body 61, a first internal electrode 62, a second internal electrode 63, a single electrode 64, and a common electrode 65, and the groove 69 is formed to form a comb-shaped stacked piezoelectric body block 600. The dummy layer 68 located on the base end side of the actuator 6 becomes the basis for connecting the alternately adjacent actuators 6 and the support 60.

[0051] The stacked piezoelectric block 600 is fixed to the substrate 47 by bonding the end face in the Z direction to the surface of the substrate 47. The bonding surface of the substrate 47 to which the stacked piezoelectric block 600 is fixed is the surface on the base end side of the stacked piezoelectric block 600. The substrate 47 is, for example, a ceramic substrate. The ceramic substrate is, for example, an alumina substrate. The stacked piezoelectric block 600 and the substrate 47 are bonded, for example, with an adhesive. As described in detail below, the substrate 47 electrically connects the wiring electrodes formed on the surface to the external electrodes of the actuator 6. The bonded stacked piezoelectric block 600 and the substrate 47 constitute an actuator substrate 601.

[0052] Figures 6 to 10601 are a top view and a three-dimensional view of the actuator substrate 601. Figures 6 to 10 As shown in FIG. 1 , individual electrodes 64 as external electrodes formed on one side of each actuator 6 are connected to individual wirings 66 as wiring electrodes formed on the surface of the substrate 47 for each ejection channel. In addition, common electrodes 65 as external electrodes formed on the other side of each actuator 6 are connected in common to common wirings 67 as wiring electrodes formed on the surface of the substrate 47 along the arrangement direction of the actuators 6. The common wirings 67 of the ejection channels of the A column and the B column are separated by a separation groove 602 formed along the X direction in the central portion of the substrate 47.

[0053] The individual wiring 66 is led out from the stacked piezoelectric block 600 to the edge of the substrate 47 for each ejection channel. The A column is led out in a straight line along the Y direction, and the B column is led out in a straight line along the -Y direction. The edge of the substrate 47 becomes a connection portion 603 with the flexible printed wiring board 21. Since the pillar 60 is not driven, the individual wiring 66 is formed at a position corresponding to the actuator 6. The individual wiring 66 is not provided on the pillar 60, and accordingly, the pitch of the individual wiring 66 on the surface of the substrate 47 becomes coarser to twice the pitch of the groove 69, and there is a surplus space on the surface of the substrate 47. By utilizing this space, an extension portion 604 is provided on the individual wiring 66, so that the wiring width of the individual wiring 66 is expanded to be larger than the column width of the actuator 6 in the X direction. The extension portion 604 is preferably provided near the stacked piezoelectric block 600, but it is sufficient as long as it is expanded to be larger than the column width of the actuator 6 at least at the connection portion 603. The individual wirings 66 are preferably formed at the same pitch as the pitch of the actuator 6 in the X direction so that the center line of the individual wirings 66 is aligned with the center of the width of the actuator 6 in the X direction.

[0054] The common wiring 67 is formed, for example, in a straight line along the X direction, which is the arrangement direction of the actuator 6 and the pillar 60. In order to prevent current concentration during driving, the common wiring 67 has a wider wiring width than the individual wiring 66. In addition, both ends are led out to the edge of the substrate 47. The leading direction is the same direction as the individual wiring 66. That is, the common wiring 67 is formed into a "コ" shape when viewed from above, and the individual wiring 66 of each channel is arranged in parallel in the area inside the "コ" shape of the common wiring 67.

[0055] The flexible printed wiring board 21 overlaps and joins with the surface of the connection portion 603 of the substrate 47. Figure 7As shown, each individual wiring 27 of the flexible printed wiring board 21 is electrically connected to each individual wiring 66 of the substrate 47. Similarly, the common wiring 28 of the flexible printed wiring board 21 is electrically connected to the common wiring 67 of the substrate 47. The substrate 47 and the flexible printed wiring board 21 are fixed by, for example, ACF (Anisotropic Conductive Film), ACP (AnisotropicConductive paste), NCF (Non-Conductive Film), NCP (Non-Conductive paste), etc., and are anisotropically conductively connected in the thickness direction. NCF is obtained by removing conductive particles from ACF. It is an insulator itself, but it is conductive in the thickness direction by contacting the individual wiring 27 with the individual wiring 66 and the common wiring 28 with the common wiring 67 and thermally curing. Alternatively, it can also be fixed by solder or the like.

[0056] Here, the column width La in the X direction of the actuator 6 and the width Sa of the groove 69, the wiring electrode width Lb of the individual wiring 66 of the substrate 47 and the space Sb as the electrode node distance, and the wiring width Lf of the individual wiring 27 of the flexible printed wiring board 21 and the space Sf as the wiring node distance respectively have the following relationship with respect to the pitch P of the ejection channel.

[0057] Pitch P = 2 (La + Sa) = Lb + Sb = Lf + Sf

[0058] Sb≥Lb>La

[0059] Sf≥Lf>La

[0060] For example, when the pitch P is 169 μm, an example of La, Sa, Lb, Sb, Lf, Sf, and d is as follows.

[0061] La=50μm, Sa=34.5μm,

[0062] Lb=60μm, Sb=109μm,

[0063] Lf=84μm, Sf=85μm,

[0064] d=10μm

[0065] That is, since the actuator 6 and the pillar 60 are arranged alternately, P=2(Sa+La). In the above example, La is 50μm, which is smaller than half of the pitch P. Since the separate wiring 66 of the pillar 60 is not required on the substrate 47, the wiring electrode width Lb of the separate wiring 66 can be expanded while maintaining the necessary space Sb on the substrate 47. This can be achieved by, for example, the pattern shape of the exposure mask in the manufacturing process described later. In the above example, the expansion portion 604 of d=10μm is expanded from La=50μm to Lb=60μm. By expanding the wiring electrode width Lb of the separate wiring 66 on the substrate 47, the connection resistance is reduced, the ink ejection efficiency between the ejection channels is improved, and the connection reliability with the separate wiring 27 of the flexible printed wiring board 21 is improved. It is also possible to further expand the wiring electrode width Lb of the separate wiring 66, but in order to further expand the wiring electrode width Lb, it is necessary to extend the distance d of the expansion portion 604. For example, in Figure 1 In the case of the inkjet printer 10, since it is desired to reduce the interval between the inkjet heads 100 to 103 in the Y direction as much as possible and to suppress the size of the inkjet head 100 in the Y direction as much as possible, Lb is set to 60 μm.

[0066] In the flexible printed wiring board 21, the wiring width of the individual wiring 27 is further increased, for example, to Lf = 84μm, Sf = 85μm. That is, the wiring width (line) and the wiring node distance (space) on the flexible printed wiring board 21 are approximately 1:1. The wiring width Lf of the individual wiring 27 of the flexible printed wiring board 21 is 24μm larger than the wiring electrode width Lb of the individual wiring 66 of the substrate 47. When the flexible printed wiring board 21 and the substrate 47 are overlapped and connected, the goal is to make the center lines of the individual wiring 27 and the individual wiring 66 coincide with each other, but when the NCF, ACF, etc. are sandwiched for thermal compression bonding, the flexible printed wiring board 21 thermally expands, and there is also a manufacturing error in the connection position, so the center lines often cannot accurately coincide with each other. However, in the above example, the wiring width Lf of the individual wiring 27 of the flexible printed wiring board 21 is 24μm larger than the wiring electrode width Lb of the individual wiring 66 of the substrate 47, so even if the center lines are offset by a maximum of ±12μm, Lb will not exceed the range of La. Therefore, even if the center lines are offset by ±12 μm, the connection resistance between the individual wiring 27 of the flexible printed wiring board 21 and the individual wiring 66 of the substrate 47 does not change. As a result, the ejection characteristics of the ink can be made uniform between the ejection channels, thereby suppressing uneven density of printing. In addition, the wiring electrode pitch (space) on the substrate 47 does not fall below half of the pitch P, so the connection reliability can be ensured.

[0067] As an example, a comb-shaped stacked piezoelectric block 600 in which the actuators 6 and the pillars 60 are alternately arranged is manufactured as follows. First, the first internal electrode 62 and the second internal electrode 63 are formed on the main surface of the piezoelectric body 61 processed into a thin plate-like strip, and the piezoelectric bodies 61 are stacked and fired to form a whole. Then, the strip-shaped block is bonded to the surface of the substrate 47 using, for example, an adhesive. Then, a conductive film is formed on the surface of the strip-shaped block and the substrate 47 by, for example, full-surface plating.

[0068] Then, grooves 69 are formed on the strip-shaped block by, for example, machining, and the strip-shaped block is separated into the actuators 6 and the pillars 60. After the conductive film is plated on the entire surface, the individual electrodes 64 and the common electrode 65 of the actuator 6 and the individual wirings 66 and the common wirings 67 of the substrate 47 function, but at this point in time, all of them are short-circuited. Therefore, for example, a liquid resist is applied to the strip-shaped block with the grooves 69 formed therein, and the resist is exposed through a mask, and the conductive film is selectively etched, so that Figure 8 As shown, a separate electrode 64 and a separate wiring 66 are formed for each ejection channel. In addition, the selective etching also includes the removal of the conductive film on the end face of the actuator 6 connected to the vibration plate 5. It can also be removed by grinding to make the height of the end face consistent. The height of the separate electrode 64 and the separate wiring 66 in the -Z direction is different, but since the side of the actuator 6 is tilted, it is easy to expose. In addition, if the exposure height is different, there is a problem that it is difficult to obtain the accuracy of the wiring width, but the wiring electrode width Lb allows a width of Sb≥Lb>La, so it has the effect of facilitating exposure. In this method, the separate electrode 64 and the separate wiring 66 can be formed integrally using the same conductive film, but they can also be formed separately. In addition, although the separate wiring 66 of the pillar 60 is not required, the conductive film on the side of the pillar 60 equivalent to the separate electrode 64 can also be left without etching.

[0069] On the other hand, since the common electrode side is not patterned like the individual electrode side, Fig. 9 The figure shows a state where a conductive film is formed by full plating on the side surfaces of the adjacent actuators 6 and pillars 60, and on the substrate 47. That is, the common electrode 65 and the common wiring 67 can be formed integrally using the same conductive film. The edge portions of the substrate 47 extending to both ends of the common wiring 67 are formed together when the individual wiring 66 is patterned. In addition, the separation groove 602 that separates the common wiring 67 of the A column from the common wiring 67 of the B column can also be formed together when the individual wiring 66 is patterned. Since the common electrode side is not selectively etched, the inclination of the side surface of the actuator 6 can be made steeper than the individual electrode 64 side or not inclined, and the need for useless space is suppressed, thereby making the head width narrow and compact.

[0070] That is, the stacked piezoelectric block 600 has a trapezoidal shape in which one side is inclined and the other side is vertical in the strip-shaped state before being bonded to the substrate 47 or at least in the state before the groove 69 is formed. At this time, the upper end surface in the -Z direction is preferably polished to a uniform height to facilitate the subsequent bonding process with the vibration plate 5. Thus, when the groove 69 is formed in the strip-shaped block, the actuator 6 and the support 60 can be separated into trapezoidal shapes with the same height based on the surface of the substrate 47.

[0071] Then, a polarization voltage is applied to the actuator 6 via the individual wiring 66 and the common wiring 67, thereby polarizing the piezoelectric body 61 of each actuator 6. For example, a polarization power source that can apply a voltage higher than the driving voltage is connected to the individual wiring 66 and the common wiring 67 to perform polarization. Alternatively, as Fig.10 As shown, wiring for polarization may be formed in advance on the substrate 47, and after polarization, the wiring for polarization may be cut off at the position shown by the double-dashed line by the substrate 47. Alternatively, polarization may be performed via the driver IC 3 after the flexible printed wiring board 21, the driver IC 3, and the printed substrate 22 are connected.

[0072] like Fig.11 As shown in FIG. 1 , the actuator substrate 601 as the first structure thus manufactured is joined to the flow path block as the second structure formed by joining the nozzle plate 23, the pressure chamber substrate 4, the vibration plate 5, the frame 46, etc., by, for example, an adhesive. Furthermore, the flexible printed wiring board 21 and the printed substrate 22 are connected to complete the Fig.12 The inkjet head 100 shown in FIG. 2 is flexible and can be bent, so it is usually as shown in FIG. Figure 2 The printed circuit board 22 as a relay board is supplied with a driving control signal and a driving voltage power supply via a connection cable 220 .

[0073] Next, the operation of the inkjet head 100 will be described. Fig.13 is a circuit diagram of a control system of the inkjet head 100. Fig.13 As shown, the actuator 6 (#1ch, #2ch, ..., #nch) of each ejection channel connects the individual electrodes 64 to the output terminals of the driver D (i.e., the drive circuit) of the driver IC 3 via the individual wirings 66 and 27. Furthermore, the actuator 6 connects the common electrode 65 to the common potential via the common wirings 67 and 28. The common potential is, for example, ground (GND).

[0074] The driver IC 3 is connected to a power source 7 for applying a driving voltage V1 to the actuator 6 and a power source 70 for applying a driving voltage V2. The positive electrodes of the power sources 7 and 70 are connected to the driver IC 3, and the negative electrodes are connected to the ground (GND). The driver IC 3 is connected to a control substrate 17 (see FIG. 1 ) which is a control unit of the inkjet printer 10. Figure 1The print data is an example of a drive control signal supplied via the connection cable 220.

[0075] Next, refer to Fig.14 and Fig.15 The ink ejection operation is described. Each driver D of the driver IC 3 applies a drive waveform to the individual electrodes 64 of each actuator 6 using drive voltages V1, V2 and ground (GND). The voltage V1 is, for example, 20 V. The voltage V2 is, for example, 10 V. The ground (GND) is, for example, 0 V. Which actuator 6 is driven depends on, for example, the print data. Fig.14 This is an example of a driving waveform applied to the actuator 6 .

[0076] like Fig.14 As shown in FIG. 1 , when the actuator 6 is driven to apply a ground potential to the common electrode 65, a voltage V2 is applied to the individual electrode 64 to enter a standby state. When the voltage V2 is applied, an electric field is applied in the direction of the polarization axis of the piezoelectric body 61, as shown in FIG. Fig.15 As shown in (a), the actuator 6 is extended in the stacking direction (Z direction) and the volume of the pressure chamber 42 is reduced. This is done before the timing of ink ejection. Then, by Fig.14 At time t1), the potential of the individual electrode 64 is initially lowered to ground (GND). Fig.15 As shown in (b), the extended actuator 6 returns to its original state, that is, contracts relatively, and the volume of the pressure chamber 42 relatively expands. In accordance with the volume expansion of the pressure chamber 42, the ink flows into the pressure chamber 42 through the guide flow path 43.

[0077] Then, for example, after a period of 1 / 2 of the pressure vibration period of the head 2 has passed, Fig.14 When a voltage V2 is applied to the individual electrode 64 at time t2, as shown in FIG. Fig.15 As shown in (c), the actuator 6 expands in the stacking direction (Z direction) and the volume of the pressure chamber 42 is relatively reduced, thereby ejecting ink droplets R from the nozzle 24. Then, for example, after a time of 1 / 2 of the pressure vibration cycle of the head 2 has passed, Fig.14 At time t3, the voltage V1 is applied to the individual electrode 64, and at time t4 after a predetermined time, the voltage is restored to V2. Fig.15 (d)) and recovery ( Fig.15 (a)) reduces and restores the volume of the pressure chamber 42, and this action attenuates the residual vibration. In this way, the volume of the pressure chamber 42 changes in accordance with the longitudinal vibration of the actuator 6 in the stacking direction, so that ink can be ejected.

[0078] As described above, according to the above embodiment, it is possible to provide the inkjet head 100 capable of applying a driving voltage for driving each actuator 6 to the comb-teeth-shaped stacked piezoelectric block 600 in which a plurality of actuators 6 and pillars 60 are alternately arranged.

[0079] In the above embodiment, the inkjet head 100 of the inkjet printer 10 is described as an example of the liquid ejection head, but the liquid ejection head may be a modeling material ejection head of a 3D printer or a sample ejection head of a dispensing device.

[0080] That is, the liquid ejection head according to the preferred embodiment of the present invention can be expressed as follows.

[0081] (1) A liquid ejection head, comprising:

[0082] A comb-shaped stacked piezoelectric block having a plurality of piezoelectric actuators and struts alternately arranged;

[0083] a pressure chamber, engaging a portion of the partition wall with an end surface of the piezoelectric actuator;

[0084] a substrate bonded to a surface on a base end side of the stacked piezoelectric block;

[0085] a flexible substrate connected to the outer periphery of the substrate; and

[0086] The wiring electrode is formed on the substrate, connected to the external electrode of the piezoelectric actuator and connected to the wiring of the flexible substrate at the periphery of the substrate, and the electrode width at the connection portion between the substrate and the flexible substrate is larger than the column width of the piezoelectric actuator.

[0087] (2) The wiring width of the flexible substrate is larger than the electrode width of the wiring electrode at the connection portion, and the pitch of the wiring electrode is equal to the pitch of the wiring of the flexible substrate at the connection portion.

[0088] (3) The substrate and the flexible substrate are connected at the connection portion via an ACF (Anisotropic Conductive Film).

[0089] (4) Among the external electrodes of the piezoelectric actuator, a single electrode to which a driving voltage is applied is formed on a side surface of the piezoelectric actuator, and the side surface is inclined outward from the end surface toward the substrate.

[0090] (5) A common electrode among the external electrodes of the piezoelectric actuator for applying a common potential to a plurality of the piezoelectric actuators is formed on a side surface of the piezoelectric actuator, and the inclination of the side surface is larger (ie, steeper) than the inclination of the individual electrodes.

[0091] (6) The individual electrodes of each of the piezoelectric actuators and the wiring electrodes of the substrate connected to the individual electrodes and connected to the wiring of the flexible substrate at the outer periphery of the substrate are formed by an integrated conductive film.

[0092] (7) The common electrode of the piezoelectric actuator and the wiring electrode of the substrate connected to the common electrode and connected to the wiring of the flexible substrate at the outer periphery of the substrate are formed by an integral conductive film.

[0093] The embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the scope of the main purpose of the invention. These embodiments and their variations are included in the scope or main purpose of the invention, and are included in the invention recorded in the claims and their equivalents.

Claims

1. A liquid ejection head, characterized in that: have: A comb-shaped stacked piezoelectric block having a plurality of piezoelectric actuators and struts alternately arranged; a pressure chamber, engaging a portion of the partition wall with an end surface of the piezoelectric actuator; a substrate bonded to a surface on a base end side of the stacked piezoelectric block; a flexible substrate connected to the outer periphery of the substrate; as well as The wiring electrodes of the substrate are connected to the external electrodes of the piezoelectric actuator and to the wiring of the flexible substrate at the periphery of the substrate, and the electrode width at the connection between the substrate and the flexible substrate is larger than the column width of the piezoelectric actuator.

2. The liquid ejection head according to claim 1, wherein: The wiring width of the flexible substrate is larger than the electrode width of the wiring electrode at the connection portion, A pitch of the wiring electrodes is equal to a pitch of the wiring of the flexible substrate at the connection portion.

3. The liquid ejection head according to claim 1 or 2, characterized in that: The substrate and the flexible substrate are connected at the connection portion through an anisotropic conductive film.

4. The liquid ejection head according to claim 1, wherein: A single electrode to which a driving voltage is applied among the external electrodes of the piezoelectric actuator is formed on a side surface of the piezoelectric actuator, and the side surface is inclined outward from the end surface toward the substrate.

5. The liquid ejection head according to claim 4, wherein: Among the external electrodes of the piezoelectric actuator, a common electrode for applying a common potential to a plurality of the piezoelectric actuators is formed on a side surface of the piezoelectric actuator, and an inclination of the side surface is greater than an inclination of the individual electrodes.

6. The liquid ejection head according to claim 4, wherein: The individual electrodes of the piezoelectric actuator and the wiring electrodes of the substrate connected to the individual electrodes and connected to the wirings of the flexible substrate at the outer periphery of the substrate are formed by an integrated conductive film.

7. The liquid ejection head according to claim 5, wherein: The common electrode of the piezoelectric actuator and the wiring electrode of the substrate connected to the common electrode and connected to the wiring of the flexible substrate at the outer periphery of the substrate are formed by an integrated conductive film.

8. The liquid ejection head according to claim 1, wherein: The liquid ejection head prints an image as a sheet passes underneath.

9. The liquid ejection head according to claim 1, wherein: The liquid ejection head ejects ink.

10. The liquid ejection head according to claim 9, wherein: The colors of the ink are cyan, magenta, yellow and black.

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