Liquid discharge head

Abstract

To provide a low-cost highly implementable liquid discharge head.SOLUTION: This liquid discharge head comprises: an actuator member which includes a plurality of piezoelectric elements and in which a plurality of electrodes are formed; and a wiring board disposed to face the surface of the actuator member and electrically connected to the electrodes. The wiring board includes three or more through-holes, and the base member connected to the actuator member or the actuator member and the wiring board are joined at the through-holes.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In liquid ejection devices such as inkjet printer heads, actuator members using piezoelectric materials such as PZT are used as the drive source for the liquid ejection head. In inkjet printer heads, actuator elements (drive elements) are arranged at very fine intervals, and the wiring for driving them is also very fine. For example, to accommodate wiring with a fine pitch of around 100 μm, a flexible printed circuit board (hereinafter referred to as FPC) may be directly soldered to the electrodes of the actuator member.

[0003] In addition, in order to align the electrodes of the FPC and the actuator member, protrusions or holes may be formed on the FPC or the actuator member, and the electrodes may be aligned by fitting them together. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-201832 A Summary of the Invention [Problem to be solved by the invention]

[0005] The problem to be solved by the present invention is to provide a liquid ejection head that is low cost and easy to mount. [Means for solving the problem]

[0006] A liquid ejection head according to one embodiment comprises an actuator member having a plurality of piezoelectric elements and having a plurality of electrodes formed thereon, and a wiring substrate arranged opposite the surface of the actuator member and electrically connected to the plurality of electrodes, the wiring substrate having three or more through holes, and a base member connected to the actuator member or the actuator member is joined to the wiring substrate at the through holes. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view showing the configuration of a portion of a liquid ejection head according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing a configuration of a part of the liquid ejection head. [Figure 3] FIG. 2 is a side view showing a configuration of a part of the liquid ejection head. [Figure 4] FIG. 2 is a side view showing a configuration of a part of the liquid ejection head. [Figure 5] FIG. 1 is an explanatory diagram showing a schematic configuration of a liquid ejection device according to a first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] A liquid ejection head 1 and a liquid ejection device 100 according to a first embodiment will be described below with reference to Figs. 1 to 5. Figs. 1 and 2 are cross-sectional views showing the configuration of a portion of the liquid ejection head 1, and Figs. 3 and 4 are side views showing the configuration of a portion of the liquid ejection head 1. Fig. 5 is an explanatory diagram showing the schematic configuration of the liquid ejection device 100. In the figure, arrows X, Y, and Z indicate three mutually orthogonal directions. For the purpose of explanation, the configuration is enlarged, reduced, or omitted in each figure as appropriate.

[0009] As shown in Figures 1 and 2, the liquid ejection head 1 is an inkjet head comprising a base member 10, a pair of actuator members 20, a flow path member 40, a nozzle plate 50 having a plurality of nozzles 51, a frame portion 60 as a structural portion, and a drive circuit 70.

[0010] As an example, the liquid ejection head 1 includes two actuator members 20, which are piezoelectric members, and includes two nozzle rows in which a plurality of nozzles 51 are arranged in a row direction (X direction), two pressure chamber rows in which a plurality of pressure chambers 31 are arranged in the row direction, and two element rows in which a plurality of piezoelectric elements 21, 22 are arranged in the row direction. In this embodiment, an example is shown in which the stacking direction of the plurality of piezoelectric layers 211, the vibration direction of the piezoelectric elements 21, and the vibration direction of the vibration plate 30 are all along the Z direction.

[0011] The base member 10 supports a pair of actuator members 20. The base member 10 is configured, for example, in the shape of a plate. The base member 10 may be a circuit board.

[0012] The actuator member 20 is provided on one side of the base member 10. For example, two actuator members 20 are arranged side by side in the Y direction.

[0013] The actuator member 20 includes a plurality of drive piezoelectric elements 21 and a plurality of non-drive piezoelectric elements 22 that are arranged alternately along the column direction and serve as actuators, and a connecting portion 26 that integrally connects these plurality of piezoelectric elements 21, 22 on the side of the base member 10. The actuator member 20 is a laminated piezoelectric member 201 in which a plurality of piezoelectric layers 211 and a plurality of internal electrodes 221, 222 are laminated.

[0014] In the actuator member 20, a plurality of drive piezoelectric elements 21 and a plurality of non-drive piezoelectric elements 22 are arranged in one direction at regular intervals.

[0015] As an example, the plurality of drive piezoelectric elements 21 and the plurality of non-drive piezoelectric elements 22 are each configured in the shape of a rectangular parallelepiped pillar with the same external shape. A plurality of grooves 23 are formed on one side of the actuator member 20, dividing one end into a plurality of drive piezoelectric elements 21 and non-drive piezoelectric elements 22. The plurality of drive piezoelectric elements 21 and non-drive piezoelectric elements 22 are aligned in the column direction at the same pitch by grooves 23 of the same width in the alignment direction. Furthermore, since the depth of the grooves 23 of the actuator member 20 is set to be smaller than the overall length of the actuator member 20 in the Z direction, a connecting portion 26 that connects the plurality of elements 21, 22 together is formed on the base member 10 side from the bottom of the grooves 23.

[0016] The connecting portion 26 is a block-shaped member that is disposed on the base end side of the plurality of piezoelectric elements 21, 22 and connects the plurality of piezoelectric elements 21, 22. That is, the connecting portion 26 is configured as a plate-like member whose longitudinal direction is in the X direction and whose layers are continuous over the entire longitudinal length of the laminated piezoelectric member 201.

[0017] Individual electrodes constituting the external electrode 223 are formed on one side surface of the actuator member 20, which is an end surface in the Y direction different from the Z direction. The individual electrodes are, for example, a plurality of line patterns spaced apart from one another on one side surface of the actuator member 20. In other words, on one side surface of the actuator member 20, external electrodes 223 each having a plurality of line patterns spaced apart from one another and electrode removal portions where the electrode layer has been removed by PEP or the like are alternately formed.

[0018] One side surface constitutes a mounting portion where ACF mounting or solder mounting is performed. As an example, an FPC 71 is electrically and mechanically connected to the individual electrodes on one side surface of the actuator member 20 by solder mounting or ACF mounting. For example, the side surface on which the mounting portion is formed and the other side surface on the opposite side form a surface perpendicular to the stacking direction.

[0019] Furthermore, a common electrode constituting the external electrode 224 is formed on the other side surface of the actuator member 20 in the Y direction. The common electrode has an electrode layer formed on the entire surface of the other side surface of the actuator member 20.

[0020] For example, the multiple driving piezoelectric elements 21 and the multiple non-driving piezoelectric elements 22 are each configured in a rectangular shape when viewed in a plan view from the Z direction, with the short side direction aligned with the column direction of the element row and the long side direction aligned with an extension direction perpendicular to the column direction and the Z direction.

[0021] The driving piezoelectric elements 21 are arranged in positions in the Z direction opposite the plurality of pressure chambers 31 formed in the flow path member 40. As an example, the center positions in the column direction and extension direction of the driving piezoelectric elements 21 and the center positions in the column direction and extension direction of the pressure chambers 31 are arranged side by side in the Z direction.

[0022] The non-driven piezoelectric elements 22 are arranged in positions in the Z direction facing the plurality of partition walls 42 formed in the flow path member 40. As an example, the center positions in the column direction and extension direction of the non-driven piezoelectric elements 22 and the center positions in the column direction and extension direction of the partition walls 42 are arranged side by side in the Z direction.

[0023] For example, the actuator member 20 is formed by dicing a laminated piezoelectric member 201 previously bonded to a base member 10 from the end face opposite the base member 10 side to form grooves 23, thereby forming a plurality of rectangular columnar piezoelectric elements at predetermined intervals. Then, an electrode layer is formed on the formed columnar elements, and a plurality of driving piezoelectric elements 21 and a plurality of non-driving piezoelectric elements 22 are formed, which are alternately arranged. The plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22 are alternately arranged in parallel in the column direction, with the grooves 23 sandwiched between them.

[0024] For example, the laminated piezoelectric member 201 that constitutes the actuator member 20 is formed by laminating and sintering sheet-shaped piezoelectric materials.

[0025] The piezoelectric members constituting the driving piezoelectric element 21 and the non-driven piezoelectric element 22 are, for example, laminated piezoelectric members 201. The driving piezoelectric element 21 and the non-driven piezoelectric element 22 each include a plurality of laminated piezoelectric layers 211 and internal electrodes 221, 222 formed on the main surfaces of the piezoelectric layers 211. As an example, the driving piezoelectric element 21 and the non-driven piezoelectric element 22 have the same laminated structure. The driving piezoelectric element 21 and the non-driven piezoelectric element 22 each include external electrodes 223, 224 formed on the surfaces thereof.

[0026] The piezoelectric layer 211 is formed in a thin plate shape from a piezoelectric ceramic material such as PZT (lead zirconate titanate) or lead-free KNN (potassium sodium niobate). The multiple piezoelectric layers 211 are stacked with their thickness direction aligned with the stacking direction and are bonded to each other. For example, in this embodiment, the thickness direction and stacking direction of the piezoelectric layers 211 are arranged along the vibration direction (Z direction).

[0027] The internal electrodes 221, 222 are conductive films formed into a predetermined shape using a sinterable conductive material such as silver-palladium. The internal electrodes 221, 222 are formed in predetermined regions on the main surface of each piezoelectric layer 211. The internal electrodes 221, 222 have opposite polarities. For example, one internal electrode 221 is formed in a region that reaches one end of the piezoelectric layer 211 but does not reach the other end of the piezoelectric layer 211 in the extension direction (Y direction), which is a direction perpendicular to both the row direction (X direction) in which the multiple drive piezoelectric elements 21 and the multiple non-drive piezoelectric elements 22 are arranged and the vibration direction (Z direction). The other internal electrode 222 is formed in a region that does not reach one end of the piezoelectric layer 211 but reaches the other end of the piezoelectric layer 211 in the extension direction. The internal electrodes 221, 222 are connected to external electrodes 223, 224 formed on the side surfaces of the piezoelectric elements 21, 22, respectively.

[0028] Furthermore, the laminated piezoelectric member 201 constituting the drive piezoelectric element 21 and the non-drive piezoelectric element 22 further includes a dummy layer 212 on either or both of the ends on the base member 10 side and the nozzle plate 50 side. The dummy layer 212 is made of, for example, the same material as the piezoelectric layer 211, has an electrode on only one side, and is not deformed because no electric field is applied. For example, the dummy layer 212 does not function as a piezoelectric member, but serves as a base for fixing the actuator member 20 to the base member 10, or as a polishing allowance for polishing to achieve precision during and after assembly.

[0029] The external electrodes 223, 224 are formed on the surfaces of the plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22, and are configured by gathering the ends of the internal electrodes 221, 222. For example, the external electrode 223 is formed on one end face of the piezoelectric layer 211 in the extension direction. The external electrode 224 is formed on the other end surface of the piezoelectric layer 211 in the extension direction.

[0030] The external electrodes 223 and 224 are formed by a known method such as plating or sputtering using Ni, Cr, Au, or the like. The external electrodes 223 and 224 have different polarities. The external electrodes 223 and 224 are disposed on different side surfaces of the plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22, respectively.

[0031] In this embodiment, as an example, the external electrode 223 is an individual electrode, and the external electrode 224 is a common electrode. The external electrodes 223, which serve as individual electrodes for the plurality of drive piezoelectric elements 21 and the plurality of non-drive piezoelectric elements 22, are arranged independently of each other by patterning an electrode layer formed on one side surface of the laminated piezoelectric member 201 in the manufacturing process.

[0032] The external electrodes 223 are connected to the drive circuit 70 on a side surface of the actuator member 20 via an FPC 71 serving as a flexible substrate, which is an example of a wiring board. For example, each external electrode 223 is connected to the control unit 116 serving as a drive unit via a drive IC 72 of the drive circuit 70 by the FPC 71, and is configured to be drive-controllable under control of the control circuit 1161. The external electrode 224 may be routed to the side surface on the external electrode 223 side, and connected to the drive circuit 70 via the FPC 71.

[0033] The external electrode 224 formed on the other end surface of the actuator member 20 has a configuration in which the groove 23 is shallower than the end of the electrode layer on the base member 10 side, so that the electrode layer is continuous with the other side surface of the laminated piezoelectric member 201 in an area closer to the base member 10 than the bottom of the groove 23, thereby forming a common electrode. The external electrode 224 is, for example, grounded.

[0034] The dummy layer 212 is made of the same material as the piezoelectric layer 211. The dummy layer 212 has an electrode on only one side and is not subjected to an electric field, so it does not deform. In other words, the dummy layer 212 does not function as a piezoelectric layer, but serves as a base for fixing, or as a polishing allowance for polishing to achieve precision during and after assembly. The end face of the actuator member 20 on the side where the individual electrodes are arranged is chamfered, and a retraction surface 25 is formed that is inclined so as to retract toward the base member 10 in a direction away from the FPC 70. The retraction surface 25 is provided, for example, on the dummy layer 212. In other words, the portion of the actuator member 20 that does not function as a piezoelectric body and does not deform is partially cut out.

[0035] The vibration direction of each of the piezoelectric elements 21 and 22 is along the stacking direction, and when an electric field is applied, they are displaced in the d33 direction.

[0036] For example, each of the piezoelectric elements 21 and 22 has 3 to 50 layers, each layer having a thickness of 10 to 40 μm, and the product of the thickness and the total number of layers is less than 1000 μm.

[0037] The driving piezoelectric element 21 vibrates when a voltage is applied to the internal electrodes 221 and 222 via the external electrodes 223 and 224. In this embodiment, the driving piezoelectric element 21 vibrates longitudinally along the stacking direction of the piezoelectric layer 211. The longitudinal vibration here refers to, for example, "vibration in the thickness direction defined by the piezoelectric constant d33." The driving piezoelectric element 21 displaces the vibration plate 30 and deforms the pressure chamber 31 by the longitudinal vibration.

[0038] The flow path member 40 includes a vibration plate 30 disposed opposite one side of the actuator member 20 in the deformation direction, and a flow path substrate 405 laminated on one side of the vibration plate 30.

[0039] The vibration plate 30 is provided between the flow path substrate 405 and the actuator member 20 in the vibration direction. The vibration plate 30, together with the flow path substrate 405, constitutes the flow path member 40. The vibration plate 30 extends in a direction intersecting the side surfaces of the laminated piezoelectric member 201 on which the individual electrodes and the common electrode are formed.

[0040] The vibration plate 30 extends along a plane perpendicular to the Z direction, which is the vibration direction, and is bonded to one side in the vibration direction of the piezoelectric layer 211 of the plurality of piezoelectric elements 21, 22, i.e., the surface on the nozzle plate 50 side. The vibration plate 30 is configured to be deformable, for example. The vibration plate 30 is bonded to the drive piezoelectric elements 21 and non-drive piezoelectric elements 22 of the actuator member 20 and to a frame portion 60. For example, the vibration plate 30 has a vibration region 301 facing the piezoelectric elements 21, 22, and a support region 302 facing the frame portion 60.

[0041] The vibration region 301 is, for example, in the form of a flat plate arranged such that the thickness direction coincides with the vibration direction of the piezoelectric layer 211. The vibration plate 30 has a surface extending in the direction in which the multiple drive piezoelectric elements 21 and the multiple non-drive piezoelectric elements 22 are arranged. The vibration plate 30 is, for example, a metal plate. The vibration plate 30 has multiple vibration parts that face each pressure chamber 31 and can be displaced individually. The vibration plate 30 is formed by integrally connecting the multiple vibration parts.

[0042] As an example, the vibration plate 30 is made of a nickel or SUS plate, and is configured to have a thickness dimension along the vibration direction of approximately 5 μm to 15 μm. Note that the vibration region 301 may have folds or steps formed in areas adjacent to a vibration region or between adjacent vibration regions to facilitate displacement of multiple vibration regions. The vibration region 301 is deformed when the area opposite the drive piezoelectric element 21 is displaced due to expansion and compression of the drive piezoelectric element 21. For example, since the vibration plate 30 needs to be very thin and have a complex shape, it is formed by electroforming or the like. The vibration plate 30 is joined to the upper end surface of the actuator member 20 by adhesive or the like.

[0043] The support region 302 is a plate-like member disposed between the frame portion 60 and the flow path substrate 405. The support region 302 has a communication portion 33 having a through-hole communicating with the common chamber 32.

[0044] For example, the communication portion 33 includes a filter member having a large number of pores as through-holes through which liquid can pass.

[0045] The flow path substrate 405 is disposed between the nozzle plate 50 and the vibration plate 30 in the vibration direction. The flow path substrate 405 is bonded to one side of the vibration plate 30 in the vibration direction.

[0046] The flow path substrate 405 has wall members such as a guide wall portion 41 and a partition portion 42, and forms a predetermined ink flow path having a plurality of pressure chambers 31 that are separated from each other, and a plurality of individual flow paths that are separated from each other and connect the pressure chambers 31 to a common chamber 32.

[0047] Within the flow path substrate 405, the multiple pressure chambers 31 are separated by partition walls 42. That is, both sides of the pressure chambers 31 in the parallel arrangement direction are formed by partition walls 42. Each pressure chamber 31 communicates with a nozzle 51 formed in a nozzle plate 50 disposed on one side. Furthermore, the pressure chamber 31 is closed on the side opposite the nozzle plate 50 by a vibration plate 30.

[0048] The multiple pressure chambers 31 are spaces formed on one side of the vibration region 301 of the vibration plate 30, and communicate with the common chamber 32 via individual flow paths and communication parts 33. The multiple pressure chambers 31 communicate with nozzles 51 formed in the nozzle plate 50. In addition, the pressure chambers 31 are closed on the side opposite to the nozzle plate 50 by the vibration plate 30.

[0049] The pressure chambers 31 hold liquid supplied from a common chamber 32 and are deformed by vibration of a vibration plate 30 that forms part of the pressure chambers 31, thereby ejecting the liquid from the nozzles 51.

[0050] The partition wall portions 42 are wall members that separate the multiple pressure chambers 31 lined up in the parallel direction and that form both side portions of the pressure chambers 31. The partition wall portions 42 are disposed opposite the non-driven piezoelectric elements 22 via the vibration plate 30, and are supported by the non-driven piezoelectric elements 22. A plurality of partition wall portions 42 are provided at the same pitch as the pitch at which the multiple pressure chambers 31 are lined up.

[0051] The nozzle plate 50 is configured as a square plate with a thickness of approximately 10 μm to 100 μm, made of a metal such as SUS or Ni, or a resin material such as polyimide. The nozzle plate 50 is disposed on one side of the flow path substrate 405 so as to cover the openings on one side of the pressure chambers 31.

[0052] A plurality of nozzles 51 are arranged in a first direction, which is the same as the arrangement direction of the pressure chambers 31, to form a nozzle row. For example, two rows of nozzles 51 are provided, and each nozzle 51 is provided at a position corresponding to the plurality of pressure chambers 31 arranged in the two rows. In this embodiment, the nozzles 51 are provided at the end positions of the pressure chambers 31 in the extension direction.

[0053] The frame portion 60 is a structure that is bonded to the vibration plate 30 together with the piezoelectric elements 21 and 22. The frame portion 60 is provided on the side of the vibration plate 30 opposite the flow path substrate 405 of the piezoelectric elements 21 and 22, and is disposed adjacent to the actuator member 20 in this embodiment, for example. The frame portion 60 forms the outer shell of the liquid ejection head 1. The frame portion 60 may also form a liquid flow path therein. In this embodiment, the frame portion 60 is bonded to the other side of the vibration plate 30, and forms a common chamber 32 between itself and the vibration plate 30.

[0054] The common chamber 32 is formed inside the frame portion 60 and communicates with the pressure chamber 31 through a communication portion 33 provided in the diaphragm 30 and an individual flow path.

[0055] The drive circuit 70 comprises an FPC 71 (Flexible printed circuits) connected to the actuator member 20 via various wiring, a drive IC 72 mounted on the FPC 71, and a printed wiring board mounted on the other end of the FPC 71.

[0056] The drive circuit 70 applies a drive voltage to the external electrodes 223 and 224 by the drive IC 72 to drive the drive piezoelectric element 21 , increase or decrease the volume of the pressure chamber 31 , and cause droplets to be ejected from the nozzle 51 .

[0057] The FPC 71 is connected to the side surface of the actuator member 20, and is connected to a plurality of external electrodes 223, 224 of the actuator member 20. As the FPC 71, a COF (Chip on Film) on which a driving IC 72, which is an electronic component, is mounted is used.

[0058] The FPC 71 has a wiring layer 711 formed in a predetermined pattern. The FPC 71 has a wiring joint 72 that is joined to the side surface of the actuator member 20 on which the external electrode 223 is formed. At this time, the external electrode 223 and the wiring layer 711 are arranged opposite each other, and are electrically connected at the wiring joint 72 by, for example, solder mounting or ACF mounting using an anisotropic conductive film. The wiring layer 711 is formed in a pattern shape that avoids the through-hole 712.

[0059] The FPC 71 has a plurality of through holes 712 formed therein and has adhesive portions 80 that are bonded to the actuator member 20 or the base member 10 by adhesive material 81 supplied through the through holes 712. In this embodiment, the through holes 712 are formed in a portion that faces the base member 10. The FPC 71 has adhesive portions 80 at a plurality of locations that are bonded to the base member 10 by adhesive material 81 provided in the through holes 712. For example, the through holes 712 are provided in three locations, on the left, right, and center, and adhesive portions 80 are provided at these three locations. In the FPC 71, the through holes 712 are arranged in a portion where the wiring layer 711 is not formed. For example, the through holes 712 are circular holes and have a diameter corresponding to the width dimension of the rows of the piezoelectric elements 21 and 22. In other words, one through hole 712 is provided in an area that spans the plurality of piezoelectric elements 21 and 22 in the parallel direction.

[0060] The bonding material 81 is a photocurable adhesive or an insulating adhesive. The bonding material 81 comes into contact with the periphery of the through hole 712 of the FPC 71 and the outer surface of the base member 10 and hardens, thereby bonding and fixing the FPC 71 and the base member 10 together. For example, the bonding material 81 is disposed on both sides in the thickness direction of the FPC 71, i.e., on the front and back sides, extending outward beyond the inner edge of the through hole 712 on the outer surface of the FPC 71, and is adhered to the periphery of the through hole 712 of the FPC 71 and also to the outer surface of the base member 10 disposed opposite the back side of the FPC 71. The bonding material 81 comes into contact with, for example, a position that avoids the wiring layer 711 of the FPC 71 and hardens.

[0061] The driving IC 72 is connected to the external electrodes 223 and 224 via the FPC 71. The driving IC 72 is an electronic component used for ejection control.

[0062] The drive IC 72 generates control signals and drive signals for operating each drive piezoelectric element 21. The drive IC 72 generates control signals for controlling, for example, the timing of ink ejection and the selection of drive piezoelectric elements 21 for ink ejection, in accordance with an image signal input from the control unit 116 of the liquid ejection device 100 in which the liquid ejection head 1 is mounted. The drive IC 72 also generates a voltage, i.e., a drive signal, to be applied to the drive piezoelectric elements 21 in accordance with the control signal from the control unit 116. When the drive IC 72 applies the drive signal to the drive piezoelectric elements 21, the drive piezoelectric elements 21 displace the diaphragm 30, driving the drive piezoelectric elements 21 to change the volume of the pressure chambers 31. This causes pressure vibrations in the ink filled in the pressure chambers 31. The pressure vibrations cause ink to be ejected from the nozzles 51 connected to the pressure chambers 31. The liquid ejection head 1 may be configured to achieve gradation expression by changing the amount of ink droplets that land on one pixel. The liquid ejection head 1 may also be configured to change the amount of ink droplets that land on one pixel by changing the number of ink ejections. In this way, the driving IC 72 is an example of an application unit that applies a driving signal to the driving piezoelectric element 21.

[0063] For example, the drive IC 72 includes a data buffer, a decoder, and a driver. The data buffer stores print data for each drive piezoelectric element 21 in chronological order. The decoder controls the driver for each drive piezoelectric element 21 based on the print data stored in the data buffer. The driver outputs a drive signal that operates each drive piezoelectric element 21 under the control of the decoder. The drive signal is, for example, a voltage applied to each drive piezoelectric element 21.

[0064] The printed wiring board is a PWA (Printing Wiring Assembly) on which various electronic components and connectors are mounted, and has a head control circuit. The printed wiring board is connected to the control unit 116 of the liquid ejection device 100.

[0065] In the liquid ejection head 1 configured as described above, the nozzle plate 50, frame portion 60, flow path substrate 405, and diaphragm 30 form an ink flow path having a plurality of pressure chambers 31 communicating with the nozzles 51 and a common chamber 32 communicating with each of the pressure chambers 31. For example, the common chamber 32 communicates with a cartridge, and ink is supplied to each pressure chamber 31 through the common chamber 32. All of the driving piezoelectric elements 21 are connected by wiring so that a voltage can be applied. In the liquid ejection head 1, when the control unit 116 of the liquid ejection device 100 applies a driving voltage to the electrodes 221, 222 using the driving IC 72, the driving piezoelectric element 21 to be driven vibrates, for example, in the stacking direction, i.e., in the thickness direction of each piezoelectric layer 211. In other words, the driving piezoelectric element 21 vibrates vertically.

[0066] Specifically, the control unit 116 applies a drive voltage to the internal electrodes 221, 222 of the drive piezoelectric element 21 to be driven, thereby selectively driving the drive piezoelectric element 21 to be driven. Then, the drive piezoelectric element 21 to be driven deforms the vibration plate 30 by combining deformation in the tensile direction and deformation in the compressive direction, thereby changing the volume of the pressure chamber 31, thereby guiding liquid from the common chamber 32 and ejecting it from the nozzle 51.

[0067] An example of a manufacturing method for the liquid ejection head 1 according to this embodiment will be described. First, the internal electrodes 221, 222 are formed by printing on a sheet-shaped piezoelectric material. Then, a plurality of piezoelectric layers 211 each having the internal electrodes 221, 222 are stacked, followed by firing and polarization processes to form the laminated piezoelectric member 201.

[0068] Then, the piezoelectric elements 21 of the laminated piezoelectric member 201, on which the internal electrodes 221, 222 have been formed in advance, are polarized, and the laminated piezoelectric member 201 is attached to the base member 10 with an adhesive or the like. For example, when configuring two actuator members 20, the integrally configured laminated piezoelectric member 201 may be joined to the base member 10 and then divided into two by groove processing or the like, or the two laminated piezoelectric members 201 that configure the two actuator members 20 may be prepared separately.

[0069] Then, with the laminated piezoelectric member 201 placed on the base member 10, the surfaces of the base member 10 and the laminated piezoelectric member 201 are processed using a tool such as a diamond cutter to shape the outer surface of the laminated piezoelectric member 201. This ensures the flatness of the top surface of the actuator member 20 to which the vibration plate 30 will be bonded in a later process.

[0070] Next, electrode layers that become the external electrodes 223, 224 are formed by printing on one and the other end faces of the laminated piezoelectric member 201. As an example, an electrode may be formed once on the top of the actuator member 20, and in this case, the electrode on the top of the actuator member 20 is removed by polishing or the like to separate the external electrodes 223, 224 from each other.

[0071] Next, the electrode layer formed on one side surface is patterned and divided into individual portions. For example, in a patterning method, the electrode layer is partially removed by forming shallow grooves in the surface using a PEP method or laser processing. That is, the electrode layer formed on the end surface of the laminated piezoelectric member 201 is divided into multiple rows in the X direction, and multiple line patterns of external electrodes 223 corresponding to the pressure chambers 31 and electrode removal portions where the electrode layer is partially removed between multiple adjacent external electrodes 223 are formed alternately.

[0072] Next, a portion of one end of the side of the actuator member 20 on which the external electrode 223 is formed, which is the side facing the base member 10, is removed and chamfered. Next, a tool such as a diamond cutter is moved in the Z direction to perform processing, thereby forming multiple grooves 23 in the actuator member 20. At this time, the multiple grooves 23 are simultaneously formed at a predetermined pitch, and the laminated piezoelectric member 201 is divided into multiple pieces, thereby forming multiple columnar elements that will become the multiple piezoelectric elements 21, 22 arranged at the same pitch. As a result of the above, multiple drive piezoelectric elements 21 and non-drive piezoelectric elements 22 arranged at the same pitch are formed.

[0073] Here, the groove 23 has a depth that does not reach the entire length of the actuator member 20, so that a part of the groove 23 remains, and a connecting portion 26 is formed in an area closer to the base member 10 than the bottom surface of the groove 23.

[0074] After patterning and processing of the groove 23, the electrode layer on the other side of the connecting portion 26 forms an external electrode 224 as a continuous common electrode.

[0075] Furthermore, wiring joints 72 are formed by, for example, solder mounting or ACF mounting using anisotropic conductive film, to electrically and mechanically connect an FPC 71 mounted with electronic components such as a drive IC 72 serving as a control component to a mounting portion on the side surface of the actuator member 20, and bonding material 81 is applied to a plurality of through holes 712 of the FPC 71 arranged opposite the base member 10 so as to contact the periphery of the through holes 712 of the FPC 71 and the outer surface of the actuator member 20, and is then cured to form adhesive parts 80 in a plurality of locations that bond the FPC 71 to the base member 10. Furthermore, a printed wiring board having a head control circuit is connected to the FPC 71.

[0076] Then, the vibration plate 30, flow path substrate 405, and nozzle plate 50 are stacked on the actuator member 20 with bonding material in between to position them, and a frame portion 60 is placed around the outer periphery of the actuator member 20. By bonding these multiple components together, the liquid ejection head 1 is completed.

[0077] An example of a liquid ejection device 100 including the liquid ejection head 1 will be described below with reference to Fig. 5. The liquid ejection device 100 includes a housing 111, a medium supply unit 112, an image forming unit 113, a medium ejection unit 114, a conveying device 115, and a control unit 116.

[0078] The liquid ejection device 100 is an inkjet recording device that performs an image formation process on paper P by ejecting a liquid such as ink while transporting the paper P as a printing medium, which is the ejection target, along a predetermined transport path R that runs from a medium supply section 112 through an image forming section 113 to a medium ejection section 114.

[0079] The housing 111 constitutes the outer shell of the liquid ejection device 100. The housing 111 has an outlet at a predetermined location for ejecting the paper P to the outside.

[0080] The medium supply unit 112 includes a plurality of paper feed cassettes, and is configured to be able to hold a stack of multiple sheets of paper P of various sizes.

[0081] The medium discharge unit 114 includes a paper discharge tray configured to be able to hold the paper P discharged from the discharge port.

[0082] The image forming section 113 includes a support section 117 that supports the paper P, and a plurality of head units 130 that are disposed above the support section 117 and face each other.

[0083] 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 plurality of belt rollers 120 that are provided on the back side of the conveyor belt 118.

[0084] During image formation, the support unit 117 supports the paper P on a holding surface, which is the upper surface of the conveyor belt 118, and conveys the paper P downstream by moving the conveyor belt 118 at a predetermined timing by the rotation of the belt roller 120.

[0085] The head unit 130 includes multiple (four color) liquid ejection heads 1, ink tanks 132 as liquid tanks mounted on each liquid ejection head 1, a connection flow path 133 connecting the liquid ejection heads 1 and the ink tanks 132, and a supply pump 134.

[0086] In this embodiment, the liquid ejection heads 1 are provided with four colors of ink: cyan, magenta, yellow, and black, and ink tanks 132 that contain ink of each color. The ink tanks 132 are connected to the liquid ejection heads 1 by connection flow paths 133.

[0087] A negative pressure control device such as a pump (not shown) is connected to the ink tank 132. The negative pressure control device controls the negative pressure inside the ink tank 132 in accordance with the head value between the liquid ejection head 1 and the ink tank 132, thereby causing the ink supplied to each nozzle 51 of the liquid ejection head 1 to form a meniscus of a predetermined shape.

[0088] The supply pump 134 is a liquid transfer pump formed, for example, by a piezoelectric pump. The supply pump 134 is provided in a supply flow path. The supply pump 134 is connected to a control circuit 1161 of the control unit 116 by wiring, and is configured to be controllable by the control unit 116. The supply pump 134 supplies liquid to the liquid ejection head 1.

[0089] The conveying device 115 conveys the paper P along a conveying path R that runs from the medium supply unit 112 through the image forming unit 113 to the medium discharge unit 114. The conveying device 115 includes a plurality of guide plate pairs 121 and a plurality of conveying rollers 122 that are arranged along the conveying path R.

[0090] Each of the guide plate pairs 121 includes a pair of plate members arranged opposite each other with the paper P being conveyed therebetween, and guides the paper P along the conveying path R.

[0091] 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 R. Sensors for detecting the conveying status of the paper are arranged at various points along the conveying path R.

[0092] The control unit 116 includes a control circuit 1161 such as a CPU (Central Processing Unit) which is a controller, a ROM (Read Only Memory) which stores various programs, a RAM (Random Access Memory) which temporarily stores various variable data, image data, etc., and an interface unit which inputs data from the outside and outputs data to the outside.

[0093] In the liquid ejection device 100 configured as described above, when the control unit 116 detects a print instruction entered by a user operating the operation input unit via an interface, for example, 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, thereby driving the liquid ejection head 1. As an ejection operation, the liquid ejection head 1 sends a drive signal to the drive IC 72 using an image signal corresponding to image data, which applies a drive voltage to the internal electrodes 221 and 222 to selectively drive the drive piezoelectric elements 21 to be ejected, causing them to vibrate vertically in the stacking direction, for example, and change the volume of the pressure chambers 31, thereby ejecting ink from the nozzles 51 and forming an image on the paper P held on the conveyor belt 118. As a liquid ejection operation, the control unit 116 drives the supply pump 134 to supply ink from the ink tank 132 to the common chamber 32 of the liquid ejection head 1.

[0094] Here, the driving operation for driving the liquid ejection head 1 will be described. The liquid ejection head 1 according to this embodiment includes driving piezoelectric elements 21 arranged opposite the pressure chambers 31, and these driving piezoelectric elements 21 are connected by wiring so that a voltage can be applied thereto. The control unit 116 sends a driving signal to the driving IC 72 based on an image signal corresponding to image data, and applies a driving voltage to the internal electrodes 221, 222 of the driving piezoelectric elements 21 to be driven, thereby selectively deforming the driving piezoelectric elements 21 to be driven. Then, the volume of the pressure chambers 31 is changed by combining the deformation in the tensile direction and the deformation in the compressive direction of the vibration plate 30, thereby ejecting liquid.

[0095] For example, the control unit 116 alternately performs a tensioning operation and a compression operation. In the liquid ejection head 1, when tensioning to increase the internal volume of the target pressure chamber 31, the drive piezoelectric element 21 to be driven is contracted, and the drive piezoelectric elements 21 that are not the drive targets are not deformed. Also, in the liquid ejection head 1, when compression to decrease the internal volume of the target pressure chamber 31 is performed, the target drive piezoelectric element 21 is expanded. Note that the non-driven piezoelectric elements 22 are not deformed.

[0096] The liquid ejection head 1 and liquid ejection device 100 according to the above-described embodiment can provide a low-cost, highly mountable liquid ejection head and liquid ejection device. Specifically, the FPC 71 can be fixed on both the front and back sides by the bonding material 81 disposed in the through-holes 712 formed in the FPC 71, ensuring high bonding strength. This prevents damage to the bonded portions when stress is applied to the FPC 71. For example, when bonding the FPC 71 to both sides of the actuator member 20, the FPC 71 is bonded on one side and then turned over to be bonded on the other side. This process easily applies stress to the FPC 71, leading to damage to the bonded portions. While stress may be applied to the wiring board during handling, this embodiment allows the bonding material 81 disposed in the through-holes 712 to easily bond the FPC 71 to the actuator member 20 or the base member 10, preventing damage to the bonded portions. Furthermore, for example, when a photocurable adhesive is used as the adhesive, the wiring board can be fixed immediately after bonding the wiring on one side and then the work of bonding the wiring on the other side can begin.

[0097] Furthermore, by providing joints at three locations, at both ends in the parallel direction and in the center, it is possible to prevent stress from being transmitted to the joints with the piezoelectric member.

[0098] The present invention is not limited to the above-described embodiment, and in the implementation stage, the components can be modified and embodied without departing from the spirit of the invention.

[0099] In the above embodiment, an example was shown in which there are three through-holes 712 and adhesive portions 80, but this is not limitative. For example, there may be four or more through-holes 712 and adhesive portions 80.

[0100] In addition, an example has been shown in which the FPC 71 has an adhesive portion 80 at a position facing the base member 10, but this is not limited to this, and for example, a through hole 712 may be provided at a position facing the actuator member 20 and the FPC 71 may be joined to the actuator member 20.

[0101] In the above embodiment, multiple piezoelectric layers 211 are stacked, and the driving piezoelectric element 21 is driven using longitudinal vibration (d33) in the stacking direction, but this is not limiting. For example, the present invention is applicable to a configuration in which the driving piezoelectric element 21 is configured from a single layer of piezoelectric material, or to a configuration in which the driving element 21 is driven by lateral vibration displacing in the d31 direction.

[0102] The arrangement of the nozzles 51 and pressure chambers 31 is not limited to that in the above embodiment. For example, the nozzles 51 may be arranged in two or more rows. Furthermore, air chambers serving as dummy chambers may be formed between a plurality of pressure chambers 31. The liquid ejection head is not limited to a circulation type, but may also be a non-circulation type, and is not limited to an end shooter type, but may also be a side shooter type liquid ejection head.

[0103] Furthermore, although an example has been shown in which the piezoelectric elements 21 and 22 have the dummy layers 212 on both ends in the stacking direction, the present invention is not limited to this, and the piezoelectric elements 21 and 22 may have the dummy layer 212 on only one side, or the piezoelectric elements 21 and 22 may not have the dummy layer 212. In addition, the configurations and positional relationships of the various components including the flow path member 40, the nozzle plate 50, and the frame portion 60 are not limited to the above example, and can be changed as appropriate.

[0104] Furthermore, in the above embodiment, an example was shown in which two actuator members 20 were arranged in parallel on the base member 10, but this is not limitative, and a single actuator member 20 may also be used.

[0105] Furthermore, 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.

[0106] Furthermore, in the above embodiment, the liquid ejection head 1 is used in a liquid ejection device such as a liquid ejection apparatus, but is not limited to this and can also be used in, for example, 3D printers, industrial manufacturing machines, and medical applications, and can be made smaller, lighter, and less expensive.

[0107] According to at least one of the embodiments described above, it is possible to provide a liquid ejection head that is low cost and easy to mount.

[0108] Although several 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 embodied 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 within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0109] 1...liquid ejection head, 10...base member, 20...actuator member, 21...driving piezoelectric element, 22...non-driving piezoelectric element, 23...groove, 25...retraction surface, 26...connecting portion, 30...vibration plate, 31...pressure chamber, 32...common chamber, 33...communicating portion, 40...flow path member, 41...guide wall portion, 42...partition wall portion, 50...nozzle plate, 51...nozzle, 60...frame portion, 70...driving circuit, 72...wiring joint portion, 80...adhesive portion, 81...bonding material, 100...liquid ejection device, 111...casing, 112...medium supply portion, 113...image forming portion, 114...medium discharge portion, 115...conveyor Feed device, 116...control unit, 117...support unit, 118...conveyor belt, 119...support plate, 120...belt roller, 121...pair of guide plates, 122...conveyor roller, 130...head unit, 132...ink tank, 133...connecting flow path, 134...supply pump, 201...laminated piezoelectric member, 211...piezoelectric layer, 212...dummy layer, 221...internal electrode, 222...internal electrode, 223...external electrode, 224...external electrode, 301...vibration region, 302...support region, 405...flow path substrate, 711...wiring layer, 712...through hole, 1161...control circuit.

Claims

1. an actuator member having a plurality of piezoelectric elements and a plurality of electrodes formed thereon; a wiring board disposed on a surface of the actuator member to face the electrodes and electrically connected to the electrodes; the wiring board has three or more through holes; A liquid ejection head, wherein a base member connected to the actuator member or the actuator member is joined to the wiring substrate at the through hole.

2. 2. The liquid ejection head according to claim 1, wherein the wiring board is an FPC.

3. The liquid ejection head according to claim 1 , wherein the wiring board and the actuator member are electrically connected by solder.

4. 2. The liquid ejection head according to claim 1, wherein the wiring board is bonded to the actuator member or the base member by a photo-curable adhesive.

5. The liquid ejection head according to claim 1 , wherein the wiring board is bonded to the actuator member or the base member with an insulating adhesive.

Images