Liquid discharge head

Abstract

To provide a liquid discharge head configured so that wiring on a substrate can be connected to an electrode of a piezoelectric actuator.SOLUTION: A liquid discharge head according to an embodiment comprises a laminate piezoelectric body block, a pressure chamber, individual electrodes, a common electrode and a substrate. A portion of a bulkhead of the pressure chamber is joined to an end face of the piezoelectric actuator. The individual electrodes are individually connected to one terminal of the piezoelectric actuator and one terminal of the other piezoelectric actuator, electrically separately from each other. The common electrode is electrically connected in common to the other terminal of the piezoelectric actuator and the other terminal of the other piezoelectric actuator. In the substrate, a plurality of individual wiring and common wiring are respectively formed on a surface thereof. In the liquid discharge head, the substrate is joined to a surface at a base end side of the laminated piezoelectric body block that is the opposite side of the end face of the piezoelectric actuator, the individual electrodes are electrically connected to the individual wiring through the surface at the base end side, and the common electrode is electrically connected to the common wiring.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] Liquid ejection heads that supply a predetermined amount of liquid to a predetermined position are known. Liquid ejection heads are mounted on, for example, inkjet printers, 3D printers, and dispensing devices. Inkjet printers eject droplets of ink from an inkjet head to form an image or the like on the surface of a recording medium. 3D printers eject droplets of modeling material from a modeling material ejection head, harden the droplets, and form a three-dimensional object. Dispensing devices eject droplets of a sample and supply a predetermined amount to a plurality of containers, etc.

[0003] A liquid ejection head has a plurality of channels for ejecting liquid. Each channel is equipped with a nozzle for ejecting liquid, a pressure chamber communicating with 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 among the plurality of channels, and applies a drive voltage to the piezoelectric actuator of the selected channel to eject the liquid. However, when a piezoelectric actuator is disposed on a substrate and a drive voltage is applied to the piezoelectric actuator via wiring on the substrate, a method for connecting the wiring on the substrate to the electrodes of the piezoelectric actuator becomes an issue. For example, in the case of wire bonding, it takes a lot of man-hours, and when plating is used, for example, the connection between the piezoelectric actuator and the substrate is prone to breakage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-263781 A [Patent Document 2] JP 2001-63036 A [Patent Document 3] JP 2017-177631 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a liquid ejection head in which wiring on a substrate and electrodes of a piezoelectric actuator can be connected. [Means for solving the problem]

[0006] A liquid ejection head according to an embodiment of the present invention includes a laminated piezoelectric block, a pressure chamber, an individual electrode, a common electrode, and a substrate. The laminated piezoelectric block has a plurality of piezoelectric actuators arranged in a comb-teeth shape. The pressure chamber has a portion of a partition wall bonded to an end face of the piezoelectric actuator. The individual electrode is individually connected to one terminal of the piezoelectric actuator, electrically isolated from one terminal of another piezoelectric actuator. The common electrode is electrically connected to the other terminal of the piezoelectric actuator, and also to the other terminal of the other piezoelectric actuator. The substrate has a plurality of individual wirings and a common wiring formed on its surface. The liquid ejection head is bonded to the substrate on the surface of the base end side of the laminated piezoelectric block, which is opposite to the end face of the piezoelectric actuator, and the individual electrodes are electrically connected to the individual wirings via the surface of the base end side, and the common electrode is electrically connected to the common wiring. [Brief description of the drawings]

[0007] [Figure 1] 1 is an overall configuration diagram of an inkjet printer equipped with an inkjet head according to an embodiment. [Diagram 2] FIG. 2 is a perspective view of the inkjet head. [Diagram 3] FIG. 2 is a partially enlarged cross-sectional view of a head portion of the inkjet head. [Figure 4] FIG. 2 is a partially enlarged cross-sectional view of a head portion of the inkjet head. [Diagram 5] FIG. 2 is a partially enlarged plan view of a head portion of the inkjet head. [Figure 6] 11A and 11B are perspective and side views of the manufacturing process of the actuator block of the head portion. [Figure 7] 11A and 11B are perspective and side views of the manufacturing process of the actuator block of the head portion. [Figure 8] 11A and 11B are perspective and side views of the manufacturing process of the actuator block of the head portion. [Figure 9] 4 is a plan view of a substrate to which the actuator block is bonded; FIG. [Figure 10] 4 is a cross-sectional view of a bonding portion between the actuator block and a substrate. FIG. [Figure 11] 11A to 11C are perspective views of a process for manufacturing an actuator substrate in which the actuator block is bonded to a substrate. [Figure 12] 11A to 11C are perspective views of a process for manufacturing an actuator substrate in which the actuator block is bonded to a substrate. [Figure 13] 11A to 11C are perspective views of a process for manufacturing an actuator substrate in which the actuator block is bonded to a substrate. [Figure 14] 3A to 3C are diagrams illustrating an assembly process of the inkjet head. [Figure 15] FIG. 4 is a circuit diagram of a control system for the inkjet head. [Figure 16] 4 shows a driving waveform applied to the actuator of the inkjet head. [Figure 17] 5A to 5C are diagrams illustrating the operation of the actuator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, a liquid ejection head according to an embodiment will be described in detail with reference to the accompanying drawings, in which the same components are denoted by the same reference numerals.

[0009] As an example of an image forming apparatus equipped with a liquid ejection head according to an embodiment, an inkjet printer 10 that prints an image on a recording medium will be described. Fig. 1 shows a schematic configuration of the inkjet printer 10. Inside a housing 11, the inkjet printer 10 has a cassette 12 that stores a sheet S, which is an example of a recording medium, an upstream transport path 13 for the sheet S, a transport belt 14 that transports the sheet S taken out of the cassette 12, a plurality of inkjet heads 100-103 that eject ink droplets toward the sheet S on the transport belt 14, a downstream transport path 15 for the sheet S, an ejection tray 16, and a control board 17. An operation unit 18 that is a user interface is disposed on the upper side of the housing 11.

[0010] Image data to be printed on the sheet S is generated, for example, by a computer 200, which is an externally connected device. The image data generated by the computer 200 is sent to a control board 17 of the inkjet printer 10 via a cable 201 and connectors 202 and 203.

[0011] The pickup roller 204 supplies 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 pair of feed rollers 131 and 132 and sheet guide plates 133 and 134. The sheet S is fed to the upper surface of the conveying belt 14 via the upstream conveying path 13. An arrow 104 in the figure indicates the conveying path of the sheet S from the cassette 12 to the conveying belt 14.

[0012] The conveyor belt 14 is a mesh-like endless belt with many through holes formed on its surface. Three rollers, a drive roller 141 and driven rollers 142 and 143, support the conveyor belt 14 so that it can rotate freely. A motor 205 rotates the conveyor belt 14 by rotating the drive roller 141. The motor 205 is an example of a drive device. In the figure, 105 indicates the rotation direction of the conveyor belt 14. A negative pressure container 206 is disposed on the back side of the conveyor belt 14. The negative pressure container 206 is connected to a fan 207 for reducing pressure. The fan 207 creates a negative pressure inside the negative pressure container 206 by forming an airflow, and adsorbs and holds the sheet S on the upper surface of the conveyor belt 14. In the figure, 106 indicates the flow of the airflow.

[0013] Inkjet heads 100-103, which are an example of liquid ejection heads, are arranged to face sheet S, which is attracted to and held on conveyor belt 14, with a small gap of, for example, 1 mm between them. Each of inkjet heads 100-103 ejects ink droplets toward sheet S. When sheet S passes below inkjet heads 100-103, the inkjet heads print images. Each of inkjet heads 100-103 has the same structure, except that they eject different colors of ink. The ink colors are, for example, cyan, magenta, yellow, and black.

[0014] The inkjet heads 100-103 are connected to ink tanks 315-318 and ink supply pressure adjusting devices 321-324 via ink flow paths 311-314, respectively. Each ink tank 315-318 is disposed above each inkjet head 100-103. During standby, each ink supply pressure adjusting device 321-324 adjusts the pressure inside each inkjet head 100-103 to a negative pressure, for example, -1.2 kPa, relative to atmospheric pressure so that ink does not leak from the nozzles 24 (see FIG. 2) of the inkjet heads 100-103. During image formation, ink from each ink tank 315-318 is supplied to each inkjet head 100-103 by the ink supply pressure adjusting devices 321-324.

[0015] After the image is formed, the sheet S is sent from the conveyor belt 14 to a downstream conveying path 15. The downstream conveying path 15 is composed of pairs of feed rollers 151, 152, 153, and 154, and sheet guide plates 155 and 156 that define the conveying path of the sheet S. The sheet S passes through the downstream conveying path 15 and is sent from a discharge port 157 to a discharge tray 16. An arrow 107 in the figure indicates the conveying path of the sheet S.

[0016] Next, a description will be given of the configuration of the inkjet heads 100 to 103. The inkjet head 100 will be described below with reference to Figures 2 to 5, but the inkjet heads 101 to 103 have the same structure as the inkjet head 100.

[0017] As shown in Fig. 2, the inkjet head 100 includes a head unit 2, which is an example of a liquid ejection unit. The head unit 2 is connected to a flexible printed wiring board 21, which is an example of a film wiring board. The flexible printed wiring board 21 is connected to a printed circuit board 22, which is an example of a relay board. The head unit 2 includes a nozzle plate 23, which is an example of a nozzle unit. The head unit 2 is connected to the ink supply pressure adjustment device 321 of Fig. 1 via an ink flow path 311.

[0018] The nozzles 24 of each ejection channel that ejects ink are arranged along a first direction, for example, the X direction, of the nozzle plate 23. The nozzle density is set within a range of 150 to 1200 dpi, for example. The nozzles 24 are not limited to being arranged in a single row, and may be arranged in multiple rows. The detailed configuration of the head unit 2 will be described later.

[0019] The flexible printed wiring board 21 is a flexible printed wiring board using a synthetic resin film such as polyimide. The flexible printed wiring board 21 is equipped with a driving IC (Integrated Circuit) 3, which is a driver chip (hereinafter referred to as a driving IC). The printed circuit board 22 is a hard through-hole board in which glass fiber-reinforced epoxy resin layers and copper wiring layers are laminated in multiple layers. The driving IC 3, which serves as a control unit for the inkjet head 100, temporarily stores data sent via the printed circuit board 22 from the control board 17, which has a CPU as a control unit for the inkjet printer 10, and provides driving signals to each channel to eject ink at a predetermined timing.

[0020] 3 to 5 are partial cross-sectional views of the head unit 2. FIG. 4 is a cross-sectional view taken along line AA in FIG. 3, and FIG. 5 is a cross-sectional view taken along line BB in FIG. 3. The nozzle plate 23 is bonded to one surface of the pressure chamber substrate 4. The nozzle plate 23 is a rectangular plate made of, for example, a resin such as polyimide or a metal such as stainless steel. The diaphragm 5 is bonded to one surface of the pressure chamber substrate 4 opposite the nozzle plate 23. The diaphragm 5 has flexibility such that it deforms when an external force is applied. The diaphragm 5 is a thin plate made of, for example, a metal such as nickel or stainless steel. The material of the diaphragm 5 may be a material other than metal, such as a polyimide film.

[0021] The pressure chambers 42 are formed in the pressure chamber substrate 4. The pressure chambers 42 are arranged at the positions of the nozzles 24 and are each connected to the nozzles 24. The pressure chamber substrate 4 is made of a metal such as stainless steel. As an example, the pressure chambers 42 are formed by forming a rectangular opening penetrating in the second direction, for example, the Z direction, in the pressure chamber substrate 4 and closing the openings on both sides with the nozzle plate 23 and the vibration plate 5, respectively.

[0022] The pressure chambers 42 communicate with guide flow paths 43 having a narrowed portion, and further communicate with an ink supply manifold 45 via ink supply ports 44 which are opening holes penetrating the vibration plate 5. The guide flow paths 43 are formed in the shape of grooves in 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 ink supply manifold 45 is formed within 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 chambers 42 of each channel via the ink supply ports 44 and guide flow paths 43 of each channel. The ink supply manifold 45 as a common ink chamber communicates with the ink flow paths 311 (see FIGS. 1 and 2).

[0023] The actuators 6 of each discharge channel are arranged at a position facing the pressure chambers 42 with the vibration plate 5 interposed therebetween. The actuators 6 are fixed by bonding the surface opposite to the vibration plate 5 in the Z direction to the surface of the substrate 47. That is, the surface of the actuator 6 that is bonded to the vibration plate 5 is the end surface of the actuator 6, and the bonding surface of the actuator 6 to the substrate 47 to which the actuator 6 is fixed is the surface on the base end side of the actuator 6. As a preferred example, as shown in FIG. 4, the actuators 6 of each channel are connected at the dummy layer 68 to form a comb-shaped actuator block 600. In this case, the surface on the base end side, which is opposite to the end surface of the actuator 6, is bonded to the substrate 47. The substrate 47 has wiring formed on its surface, which will be described in detail later. Then, the actuator 6 and the substrate 47 are bonded by, for example, thermocompression bonding, to electrically connect the wiring of the substrate 47 to the actuator 6. The bonded actuator 6 and substrate 47 constitute an actuator substrate.

[0024] The actuator 6, which is an example of a piezoelectric actuator, is a laminated piezoelectric actuator formed by alternately laminating a piezoelectric body 61 such as a piezo element, a first internal electrode 62, and a second internal electrode 63 in layers (see FIG. 3 in particular). That is, the actuator block 600 is an example of a laminated piezoelectric body block in which piezoelectric actuators are arranged in a comb-like shape. The piezoelectric bodies 61 are arranged such that the polarization directions are opposite to each other in the Z direction, for example, and are deformed in the d33 mode. The first internal electrode 62 and the second internal electrode 63 are conductive films formed on the main surfaces of the piezoelectric body 61. The first internal electrodes 62 are formed up to one end face of the actuator 6 in the Y direction, and are connected to individual electrodes 64 formed on this end face. The end face of the first internal electrode 62 located on one end face of the actuator 6 in the Y direction is an example of one terminal of the actuator 6. The individual electrodes 64 connected to one terminal of the actuator 6 are electrically isolated from the individual electrodes 64 of the other actuators 6. The second internal electrodes 63 are formed up to the other end face of the actuator 6 in the Y direction, and are connected to the common electrode 65 formed on this end face. The end face of the second internal electrode 63 located on the other end face of the actuator 6 in the Y direction is an example of the other terminal of the actuator 6. The common electrode 65 connected to the other terminal of the actuator 6 is also electrically connected to the common electrodes 65 of the other actuators 6. The dummy layer 68 is made of the same material as the piezoelectric body 61. However, the dummy layer 68 does not deform because no internal electrode is provided and no electric field is applied to it. The dummy layer 68 located on the base end side of the actuator 6 serves as a base for fixing the actuator 6 to the substrate 47.

[0025] The piezoelectric body 61 is made of a lead-containing piezoelectric material such as lead zirconate titanate (PZT) or a lead-free piezoelectric material such as sodium potassium niobate. 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. The individual electrodes 64 and the common electrode 65 are formed of Ni, Cr, Au, or the like by a known method such as plating or sputtering.

[0026] As shown in FIG. 3 in particular, the individual electrodes 64 formed on one end surface of the actuator 6 in the Y direction are further formed on the surface on the base end side of the actuator 6. Similarly, the common electrode 65 formed on the other end surface of the actuator 6 in the Y direction is further formed on the surface on the base end side of the actuator 6. The individual electrodes 64 and the common electrode 65 on the surface on the base end side of the actuator 6 are separated by a gap for insulation. On the surface on the base end side of the actuator 6, the individual electrodes 64 are respectively connected to individual wiring 66 formed for each channel on the surface of the substrate 47. Similarly, on the surface on the base end side of the actuator 6, the common electrodes 65 are commonly connected to a common wiring 67 formed on the surface of the substrate 47 along the X direction, which is the arrangement direction of the actuators 6.

[0027] The individual wiring 66 and the common wiring 67 on the surface of the substrate 47 are drawn out to one edge in the Y direction. The flexible printed wiring board 21 is composed of a resin film 26 as a base material, the individual wiring 27, the common wiring 28 (not shown), and an insulating layer 29 (e.g., an insulating film or an insulating coat). The flexible printed wiring board 21 is connected to the edge of the substrate 47, and electrically connects the individual wirings 27 and the individual wirings 66 together, and the common wiring 28 and the common wiring 67 together. The substrate 47 and the flexible printed wiring board 21 are fixed by, for example, ACF (Anisotropic Conductive Film), ACP (Anisotropic Conductive Paste), NCF (Non-Conductive Film), NCP (Non-Conductive Paste), etc., and are anisotropically conductively connected in the thickness direction. NCF is an ACF (Anisotropic Conductive Film) with the conductive particles removed, and is an insulator in itself, but is made conductive by contacting the individual wiring 27 and the individual wiring 66, and the common wiring 28 and the common wiring 67 and thermally curing them. Alternatively, they may be fixed by soldering or the like.

[0028] The pillars 60 are disposed between the actuators 6 of each discharge channel via main grooves 69 (see FIG. 4). The pillars 60 are disposed at positions corresponding to the partition walls 40 between the adjacent pressure chambers 42. The actuators 6 for driving and dummy actuators serving as the pillars 60 are formed collectively using a common piezoelectric body 61, a first internal electrode 62, a second internal electrode 63, an individual electrode 64, and a common electrode 65, and are divided into individual actuators 6 and pillars 60 by forming main grooves 69. Therefore, as shown in FIG. 4 in particular, the actuators 6 and pillars 60 of each channel are connected at the dummy layer 68, forming a comb-shaped actuator block 600 in which a plurality of actuators 6 and pillars 60 are alternately arranged. However, the pillars 60 may be formed of another material (a material other than the laminated piezoelectric body).

[0029] An actuator block 600 in which the actuators 6 and the support posts 60 arranged in the longitudinal direction X are connected and integrated at the dummy layer 68 is produced as follows, for example. First, a first internal electrode 62 and a second internal electrode 63 are formed on the main surfaces of a long piezoelectric body 61 processed into a thin plate shape, and the piezoelectric bodies 61 are stacked and baked to be integrated. Then, as shown in FIG. 6, a conductive film 601 that will later become an individual electrode 64 and a common electrode 65 is formed by plating, for example, on three surfaces excluding the surface located on the diaphragm 5 side in the Z direction and both end surfaces in the longitudinal direction in the X direction. Alternatively, the conductive film 601 may be formed on the entire surface, and then the conductive film 601 on the surface located on the diaphragm 5 side and both end surfaces in the longitudinal direction may be removed.

[0030] Thereafter, the formed conductive film 601 is divided into individual electrodes 64 for each channel, and grooves are formed to separate the individual electrodes 64 and the common electrode 65. The grooves may be formed by cutting with a laser or by machining. Also, patterning may be performed by etching or the like. FIG. 7 shows an example of laser cut grooves 602 formed by a laser. The laser cut grooves 602 are formed along the longitudinal direction in the X direction on the surface of the base end side in the Z direction of the actuator block 600, thereby separating the individual electrodes 64 and the common electrode 65. Furthermore, a groove extending from the X direction groove to the short side direction of the actuator block 600 is formed in the laser patterning range shown in FIG. 7(b), thereby separating the individual electrodes 64 for each channel halfway. The laser cut grooves 602 may be formed only in the conductive film 601, or may be formed to the surface of the piezoelectric body 61 by cutting the conductive film 601 to a thickness greater than that of the conductive film 601. The laser cut grooves 602 in the Y and Z directions which separate the individual electrodes 64 for each channel are made narrower than the width of the main grooves 69 to match the pitch of the main grooves 69 which will be formed later.

[0031] FIG. 8 shows an example of a groove (machined groove) 603 formed by machining. The machined groove 603 is formed on the surface of the base end side of the actuator block 600 along the longitudinal direction in the X direction to separate the individual electrodes 64 and the common electrode 65. The machined groove 603 in the X direction may be formed only in the conductive film 601, or may be cut to a thickness greater than the conductive film 601 and formed on the surface of the piezoelectric body 61. Furthermore, a groove extending in the short direction of the actuator block 600 from this X direction groove is formed obliquely in the YZ direction as shown by the broken line in FIG. 8(b), to separate the individual electrodes 64 for each channel. The length of the groove in the Y direction is formed to a length that connects to the main groove 69 to be formed later. Furthermore, in this case, the machined groove 603 extending obliquely in the YZ direction is made narrower than the width of the main groove 69 to match the pitch of the main groove 69.

[0032] On the other hand, the substrate 47 has a pattern of individual wiring 66 and common wiring 67 formed on its surface, as shown in FIG. 9 as a preferred example. The substrate 47 is, for example, a ceramic substrate. The ceramic substrate is, for example, an alumina substrate. The individual wiring 66 and common wiring 67 are formed by selective plating or etching. The individual wiring 66 is drawn, for example, linearly for each ejection channel from within the arrangement area of ​​the actuator block 600 shown by the dashed line in FIG. 9 to the edge of the substrate 47. Since the support 60 is not driven, the individual wiring 66 may be formed only at positions corresponding to the actuators 6, every other one of the grooves 602 (603). The wiring width of the individual wiring 66 of each ejection channel is preferably narrower than the electrode width of the individual electrode 64 of each actuator 6 on the surface of the base end side of the actuator block 600. Furthermore, it is preferable to form the individual wiring 66 at the same pitch as the pitch of each actuator 6 in the X direction and position it at the center of the width of each actuator 6 in the X direction.

[0033] The common wiring 67 is formed, for example, linearly along the X direction, which is the arrangement direction of the actuators 6 and the support columns 60, in the arrangement area of ​​the actuator block 600 shown by the dashed line in Fig. 9. The width of the common wiring 67 is made wide to prevent current concentration during driving. Both ends are drawn out to the edges of the substrate 47 in the Y direction. The drawing direction is the same as that of the individual wiring 66. That is, the common wiring 67 is formed in the shape of this character in a plan view, and the individual wiring 66 of each channel is parallel to the inner area of ​​this character of the common wiring 67. The distance between the tip of the individual wiring 66 and the common wiring 67 in the arrangement area of ​​the actuator block 600 is set to be equal to or greater than the width of the groove 602 (603) of the actuator block 600.

[0034] The actuator block 600 is placed on the substrate 47 at the position indicated by the broken line in FIG. 9, and is bonded to the surface of the substrate 47 by, for example, thermocompression bonding. As a preferred example, as shown in FIG. 10, ACF 604 is sandwiched between the surface of the base end side of the actuator block 600 and the surface of the substrate 47, and thermocompression bonding is performed to electrically connect the individual electrodes 64 and the individual wirings 66, and the common electrodes 65 and the common wirings 67. ACP, NCF, or NCP may be used instead of the ACF 604, and other materials may be used as long as they can be anisotropically conductively bonded and have conductivity in the thickness direction. FIG. 11 is a perspective view of the bonded actuator block 600 and substrate 47 (i.e., actuator substrate). The actuator block 600 does not yet have the main groove 69, so it is not brittle, and there is no particular problem even if pressure is applied during thermocompression bonding. Furthermore, since the actuator 6 is attached and polarized later, there is no problem even if polarization deterioration occurs due to application of heat during thermocompression bonding.

[0035] Thereafter, as shown in Fig. 12, the actuator 6 and the support pillar 60 are separated by forming a main groove 69 by, for example, machining. In the machining process for forming the main groove 69, the lower side of the actuator block 600, which cannot be reached by the blade for forming the groove, has the grooves 602 / 603 shown in Fig. 7 or 8 formed first, so that forming the main groove 69 electrically separates the adjacent actuators 6 and support pillars 60.

[0036] Thereafter, a polarization voltage is applied to the actuators 6 via the individual wiring 66 and the common wiring 67, thereby polarizing the piezoelectric body 61 of each actuator 6. Polarization is performed by connecting a polarization power supply capable of applying a voltage higher than that of the drive voltage power supply to the individual wiring 66 and the common wiring 67. Alternatively, as shown in Fig. 13, the polarization wiring may be formed in advance on the substrate 47, and after polarization, the polarization wiring may be cut together with the substrate 47 at the position indicated by the two-dot dashed line.

[0037] The actuator substrate, which is the first structure thus produced, is bonded, for example by adhesive, to a second structure in which the nozzle plate 23, the pressure chamber substrate 4, and the vibration plate 5 are integrated, as shown in Fig. 14. Thereafter, a frame 46 forming the ink supply manifold 45 and the like are attached, and further the flexible printed wiring board 21 and the printed board 22 are connected to complete the inkjet head 100 shown in Fig. 2.

[0038] Next, the operation of the inkjet head 100 will be described. Fig. 15 is a circuit diagram of the control system of the inkjet head 100. As shown in Fig. 15, the actuators 6 of each ejection channel (#1ch, #2ch, ... #nch) connect their individual electrodes 64 to the output terminals of the drive driver D (i.e., drive circuit) of the drive IC 3 via individual wirings 66, 27. Furthermore, the actuators 6 connect their common electrodes 65 to a common potential via common wirings 67, 28. The common potential is, for example, ground (GND).

[0039] The driving IC 3 is connected to a power source 7 that supplies a driving voltage V1 and a power source 70 that supplies a driving voltage V2 to the actuator 6. The power sources 7 and 70 have their positive terminals connected to the driving IC 3 and their negative terminals connected to ground (GND). The driving IC 3 is connected to a signal line for print data sent from a control board 17 (see FIG. 1), which is the control unit of the inkjet printer 10. The print data is an example of a control signal.

[0040] Next, the ink ejection operation will be described with reference to Figures 16 and 17. Each driving driver D of the driving IC 3 applies a driving waveform to the individual electrode 64 of each actuator 6 using driving voltages V1, V2 and ground (GND). Voltage V1 is, for example, 20V. Voltage V2 is, for example, 10V. Ground (GND) is, for example, 0V. Which actuator 6 is driven is based on, for example, print data. Figure 16 shows an example of the driving waveform applied to the actuator 6.

[0041] As shown in FIG. 16, when the actuator 6 is driven with a ground potential applied to the common electrode 65, a voltage V2 is applied to the individual electrode 64 to put it into 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, and as shown in FIG. 17(a), the actuator 6 expands in the stacking direction (Z direction), and the volume of the pressure chamber 42 is reduced. This is performed prior to the timing of ink ejection. Thereafter, by first lowering the potential of the individual electrode 64 to ground (GND) at the ink ejection timing (time t1 in FIG. 16), the expanded actuator 6 returns to its original state, that is, contracts relatively, as shown in FIG. 17(b), and the volume of the pressure chamber 42 expands relatively. Ink flows into the pressure chamber 42 through the guide flow path 43 by the amount of expansion of the volume of the pressure chamber 42.

[0042] Then, for example, after the lapse of 1 / 2 the pressure vibration period of the head unit 2, when a voltage V2 is applied to the individual electrode 64 at time t2 in FIG. 16, the actuator 6 expands in the stacking direction (Z direction) as shown in FIG. 17(c), and the volume of the pressure chamber 42 is relatively reduced, causing an ink droplet R to be ejected from the nozzle 24. Then, for example, after the lapse of 1 / 2 the pressure vibration period of the head unit 2, a voltage V1 is applied to the individual electrode 64 at time t3 in FIG. 16, and the voltage is returned to V2 at time t4 after a predetermined time. The volume of the pressure chamber 42 is reduced and restored by the expansion (FIG. 17(d)) ​​and return (FIG. 17(a)) of the actuator 6 at that time, and the residual vibration is damped by this operation. 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, and ink can be ejected.

[0043] As described above, according to the above-mentioned embodiment, it is possible to provide an actuator substrate of the inkjet head 100 capable of electrically connecting the individual wiring 66 and the common wiring 67, which are wirings on the substrate 47, to the individual electrode 64 and the common electrode 65, which are electrodes of the actuator 6. The above-mentioned embodiment has the advantage that the number of steps required to connect the wiring on the substrate 47 to the electrodes of the actuator 6 is small, and disconnection between the wiring and the electrodes is unlikely to occur. In the above embodiment, as a preferred example, both the individual electrodes 64 and the common electrode 65 are connected to the individual wiring 66 and the common wiring 67, respectively, via the surface on the base end side of the actuator block 600, but it is also possible to connect only one of them. In other words, it is also possible to connect either the individual electrode 64 or the common electrode 65 via the surface on the base end side of the actuator block 600, and connect the other by using wire bonding, electroless plating, conductive paste, or the like, without using the surface on the base end side.

[0044] The pillars 60 do not necessarily have to be arranged alternately with the actuators 6. Furthermore, the widths of the actuators 6 and the pillars 60 in the X direction may be the same or different. The widths of the actuators 6 and the pillars 60 in the X direction may be adjusted by the pitch of the main grooves 69 and the electrode separation parts (for example, the laser cut grooves 602 or the machined grooves 603). Furthermore, instead of being formed of the piezoelectric body 61 or the like like the actuators 6, the pillars 60 may be formed of a different material. For example, the pillars may be formed integrally with the support member 47.

[0045] The actuator 6 is not limited to a laminated type in which a plurality of piezoelectric bodies 61 are laminated. The piezoelectric body 61 may be a single-layer actuator. The operation of the actuator when a drive voltage is applied is not limited to longitudinal vibration. Furthermore, the actuator is not limited to a drop-on-demand piezoelectric type, and may be applied to a continuous type.

[0046] In the above embodiment, the inkjet head 100 of the inkjet printer 10 has been described as an example of a 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.

[0047] That is, a liquid ejection head according to a preferred embodiment of the present invention can be expressed as follows. (1) a laminated piezoelectric block having a plurality of piezoelectric actuators arranged in a comb-like shape; a pressure chamber in which a part of a partition wall is joined to an end surface of the piezoelectric actuator; an individual electrode that is electrically isolated from one terminal of the piezoelectric actuator and individually connected to one terminal of the other piezoelectric actuator; a common electrode electrically connected to the other terminal of the piezoelectric actuator and to the other terminal of another piezoelectric actuator; A substrate having a plurality of individual wirings and a common wiring formed on a surface thereof, the substrate is bonded to a surface of the base end side of the laminated piezoelectric block, the surface being opposite to the end face of the piezoelectric actuator; The liquid ejection head, wherein the individual electrodes are electrically connected to the individual wirings via the surface on the base end side, and the common electrode is electrically connected to the common wirings. (2) a laminated piezoelectric block having a plurality of piezoelectric actuators arranged in a comb-like shape; a pressure chamber in which a part of a partition wall is joined to an end surface of the piezoelectric actuator; an individual electrode that is electrically isolated from one terminal of the piezoelectric actuator and individually connected to one terminal of the other piezoelectric actuator; a common electrode electrically connected to the other terminal of the piezoelectric actuator and to the other terminal of another piezoelectric actuator; A substrate having a plurality of individual wirings and a common wiring formed on a surface thereof, the substrate is bonded to a surface of the base end side of the laminated piezoelectric block, the surface being opposite to the end face of the piezoelectric actuator; The liquid ejection head, wherein the common electrode is electrically connected to the common wiring via the surface on the base end side, and the individual electrodes are electrically connected to the individual wiring. (3) The common electrode is formed on the surface on the base end side separately from the individual electrodes and is electrically connected to the common wiring via the surface on the base end side. (4) The laminated piezoelectric block and the substrate are bonded by anisotropic conductive adhesive, which is thermocompression bonded via ACF, ACP, NCF, or NCP. (5) The plurality of piezoelectric actuators are integral before the laminated piezoelectric block and the substrate are bonded together, and are separated into a comb-like shape after bonding. (6) The individual electrodes on the base end side of the laminated piezoelectric block are separated for each of the piezoelectric actuators by separation grooves. (7) The separation grooves of the individual electrodes are formed by laser processing. (8) The separation grooves of the individual electrodes are formed by machining. (9) The width of the individual wiring is narrower than the width of the individual electrode.

[0048] The embodiments of the present invention 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 spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0049] 10. Inkjet Printer 100~103 Inkjet head 2 Head section 24 Nozzles 3. Driver IC 47 Substrate 6 Actuators 60 pillars 64 individual electrodes 65 Common electrode 66 Individual wiring 67 Common Wiring 600 Actuator Block 602 Laser cut groove 603 Machined Groove 604 ACF

Claims

1. a laminated piezoelectric block in which a plurality of piezoelectric actuators are arranged in a comb-like shape; a pressure chamber in which a part of a partition wall is joined to an end surface of the piezoelectric actuator; an individual electrode that is electrically isolated from one terminal of the piezoelectric actuator and individually connected to one terminal of the other piezoelectric actuator; a common electrode electrically connected to the other terminal of the piezoelectric actuator and to the other terminal of another piezoelectric actuator; A substrate having a plurality of individual wirings and a common wiring formed on a surface thereof, the substrate is bonded to a surface of the base end side of the laminated piezoelectric block, the surface being opposite to the end face of the piezoelectric actuator; The liquid ejection head, wherein the individual electrodes are electrically connected to the individual wirings via the surface on the base end side, and the common electrode is electrically connected to the common wirings.

2. a laminated piezoelectric block in which a plurality of piezoelectric actuators are arranged in a comb-like shape; a pressure chamber in which a part of a partition wall is joined to an end surface of the piezoelectric actuator; an individual electrode that is electrically isolated from one terminal of the piezoelectric actuator and individually connected to one terminal of the other piezoelectric actuator; a common electrode electrically connected to the other terminal of the piezoelectric actuator and to the other terminal of another piezoelectric actuator; A substrate having a plurality of individual wirings and a common wiring formed on a surface thereof, the substrate is bonded to a surface of the base end side of the laminated piezoelectric block, the surface being opposite to the end face of the piezoelectric actuator; The liquid ejection head, wherein the common electrode is electrically connected to the common wiring via the surface on the base end side, and the individual electrodes are electrically connected to the individual wiring.

3. The liquid ejection head according to claim 1 , wherein the common electrode is formed on the surface on the base end side separately from the individual electrodes, and is electrically connected to the common wiring via the surface on the base end side.

4. 4. The liquid ejection head according to claim 1, wherein the laminated piezoelectric block and the substrate are bonded by anisotropic conductive adhesion using thermocompression bonding via ACF, ACP, NCF or NCP.

5. 5. The liquid ejection head according to claim 4, wherein the plurality of piezoelectric actuators are integral before the laminated piezoelectric block and the substrate are bonded together, and are separated into a comb-teeth shape after bonding.

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