Liquid ejection head

Abstract

To provide a liquid ejection head in which voltage drop can be prevented and variation is less likely to occur in the operation of an actuator section.SOLUTION: At least one of the high potential electrode and the low potential electrode of the actuator member 13 has a net-like part overlapping with the plurality of drive electrodes in the vertical direction, and an outer peripheral part connecting an outer peripheral end of the net-like part. Further, a plurality of contacts 81 electrically connected to the one are arranged at random intervals along the outer peripheral part of the one among a plurality of contacts for electrically connecting the actuators 13 and the COF14.SELECTED DRAWING: Figure 15

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection head including a flow path member, an actuator member, and a wiring member. [Background technology]

[0002] Patent Document 1 describes an inkjet head (liquid ejection head) including a cavity unit (flow path member) having an upper surface with multiple pressure chambers open, a piezoelectric actuator (actuator member) arranged on the upper surface of the cavity unit, and a flexible wiring board (wiring member) arranged on the upper surface of the piezoelectric actuator. The piezoelectric actuator of Patent Document 1 includes a laminate (piezoelectric body) in which two piezoelectric material layers (piezoelectric layers) are stacked, multiple individual electrodes (first electrodes) arranged on the upper surface of the upper piezoelectric material layer, a first common constant potential electrode (third electrode) arranged on the lower surface of the lower piezoelectric material layer, and a second common constant potential electrode (second electrode) arranged between the two piezoelectric material layers and formed in a mesh pattern. The mesh pattern of the second common constant potential electrode prevents voltage drop. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-241548 Summary of the Invention [Problem to be solved by the invention]

[0004] When the electrodes are formed in a mesh pattern as in Patent Document 1, voltage drop can be prevented, but the electrode shape becomes complex, which makes it easy for unevenness to occur in the width and thickness of the electrodes, which results in uneven electrical resistance across the surface of the piezoelectric actuator and is prone to causing variations in the operation of the actuator unit.

[0005] An object of the present invention is to provide a liquid ejection head that can prevent a voltage drop and is less likely to cause variations in the operation of the actuator section. [Means for solving the problem]

[0006] A liquid ejection head according to the present invention comprises: a flow path member having an upper surface in which a plurality of pressure chambers are opened; an actuator member disposed on the upper surface of the flow path member so as to cover the plurality of pressure chambers and having a plurality of actuator portions overlapping each of the plurality of pressure chambers in a vertical direction; and a wiring member electrically connected to the actuator member via a plurality of contact points and supplying a voltage to the plurality of actuator portions through the plurality of contact points, wherein the actuator member comprises a piezoelectric body including a plurality of piezoelectric layers stacked in the vertical direction, a plurality of first electrodes overlapping each of the plurality of pressure chambers in the vertical direction, a second electrode spaced apart from the plurality of first electrodes in the vertical direction, and a wiring member electrically connected to the actuator member via a plurality of contact points and supplying a voltage to the plurality of actuator portions through the plurality of contact points. and a third electrode spaced apart from the plurality of first electrodes in the vertical direction, the piezoelectric body having a first active portion sandwiched between the first electrode and the second electrode in the vertical direction and a second active portion sandwiched between the first electrode and the third electrode in the vertical direction, the plurality of actuator portions each consisting of the first active portion and the second active portion, at least one of the second electrode and the third electrode having a mesh portion overlapping with the plurality of first electrodes in the vertical direction and an outer periphery connecting the outer edges of the mesh portion, and a plurality of first contacts supplying a voltage to one of the plurality of contacts being arranged at random intervals along the outer periphery of the one of the plurality of contacts. [Effects of the Invention]

[0007] According to the present invention, the mesh portion on at least one of the second electrode and the third electrode can prevent voltage drop. Furthermore, the randomly spaced contacts allow the charge / discharge path lengths of the actuator elements to be adjusted to be equal, reducing variations in the operation of the actuator elements. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a plan view of a printer 100 equipped with a head 10 according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of the head 10. [Figure 3] FIG. 2 is a plan view of the head 10. [Figure 4] 4 is a cross-sectional view of the head 10 taken along line IV-IV in FIG. 3. [Figure 5] 1 is a development view of a COF 14 included in the head 10 as viewed from the bottom side. [Figure 6] FIG. 3 is a plan view of the head 10 of FIG. 2, with the frame 19 and COF 14 omitted. [Figure 7] FIG. 7 is an enlarged view of region VII in FIG. 6. [Figure 8] FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7. [Figure 9] 9A to 9C are diagrams illustrating the operation of the actuator element 90 in a cross section taken along line IX-IX in FIG. 7. [Figure 10] 1 is a plan view showing the top surface of the first piezoelectric layer 41 from the top out of the four piezoelectric layers that make up the actuator member. [Figure 11] 1 is a plan view showing the top surface of the second piezoelectric layer 42 from the top out of the four piezoelectric layers that make up the actuator member. [Figure 12] 1 is a plan view showing the top surface of the third piezoelectric layer 43 from the top out of the four piezoelectric layers that make up the actuator member. [Figure 13] 1 is a plan view showing the top surface of the fourth piezoelectric layer 44 from the top out of the four piezoelectric layers that make up the actuator member. [Figure 14] 11 is a plan view showing wiring 144 of the COF arranged in the region XIV of FIG. [Figure 15] FIG. 15 is a cross-sectional view taken along line XV-XV in FIG. [Figure 16] 11 is a plan view showing wiring 145 of the COF arranged in the region XVI of FIG. [Figure 17] FIG. 17 is a cross-sectional view taken along line XVII-XVII in FIG. [Figure 18] 15 is a plan view of a head according to a second embodiment of the present invention, corresponding to FIG. 14. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] First Embodiment 1 includes a head 10 that is a first embodiment of a "liquid ejection head" according to the present invention. In the following description, the up-down direction is defined based on the state in which the printer 100 is installed for use, the front-rear direction is defined with the downstream side in the transport direction of the paper 9 being the front, and the left-right direction is defined when viewed from the front of the printer 100.

[0010] The printer 100 includes a head 10, a carriage 11 that holds the head 10, a scanning mechanism 30 that moves the carriage 11 and the head 10 left and right, a platen 7 that supports the paper 9 from below, a transport mechanism 70 that transports the paper 9 forward, and a control device 8.

[0011] The scanning mechanism 30 includes a pair of guides 31 and 32 that support the carriage 11, and a belt 33 connected to the carriage 11. The guides 31 and 32 and the belt 33 extend in the left-right direction. When the carriage motor is driven under the control of the control device 8, the belt 33 runs, and the carriage 11 and head 10 move left-right along the guides 31 and 32.

[0012] The platen 7 is disposed below the carriage 11 and the head 10. A paper sheet 9 is supported on the upper surface of the platen 7.

[0013] The transport mechanism 70 has a roller 71 arranged behind the head 10 and a roller 72 arranged in front of the head 10. The head 10, the carriage 11, and the platen 7 are arranged between the roller 71 and the roller 72 in the front-to-rear direction.

[0014] Each of rollers 71 and 72 is made up of a set of rotating members. The set of rotating members includes an upper rotating member arranged above the transport path of paper 9 and a lower rotating member arranged below the transport path of paper 9. The upper rotating member and the lower rotating member are arranged so that their peripheral surfaces are in contact with each other.

[0015] When the conveying motor is driven under the control of the control device 8, the rotating members of the rollers 71 and 72 rotate. As the rotating members of the rollers 71 and 72 rotate while nipping the paper 9, the paper 9 is conveyed forward.

[0016] 2 to 4, the head 10 includes a flow path member 12, an actuator member 13, a COF 14, driver ICs 15A and 15B, and a frame 19. The COF 14 corresponds to the "wiring member" of the present invention. The driver ICs 15A and 15B are mounted on the COF 14 and electrically connected to a control device 8 (see FIG. 1).

[0017] 2 and 3, the flow path member 12 and the frame 19 are rectangular in shape with their long sides in the front-to-rear direction in a plane perpendicular to the up-down direction. The actuator member 13, the pressing member 18, and the support member 16 are also rectangular in shape with their long sides in the front-to-rear direction in a plane perpendicular to the up-down direction.

[0018] 8, the flow path member 12 has six plates stacked in the vertical direction. A plurality of nozzles 123 are opened on the lower surface of the flow path member 12. A common flow path 121 and individual flow paths 122, each for each nozzle 123, are formed inside the flow path member 12. The individual flow paths 122 are flow paths that run from the outlet of the common flow path 121 to the nozzles 123 via the pressure chambers 12P.

[0019] 6, a plurality of pressure chambers 12P are opened on the upper surface 12X of the flow path member 12 in an area where the actuator members 13 are arranged. Four openings 129 communicating with the common flow path 121 are arranged on the front and rear sides of the upper surface 12X of the flow path member 12, sandwiching the area where the actuator members 13 are arranged. Each opening 129 communicates with an opening 191 of the frame 19 (see FIGS. 2 and 3).

[0020] As shown in FIGS. 2 to 4, the frame 19 is a rectangular frame-shaped member disposed along the periphery of the flow path member 12, and is disposed around the actuator member 13 on the upper surface 12X of the flow path member 12. Four openings 191 are provided on each of the front and rear edges of the frame 19. Each opening 191 communicates with the opening 129 of the flow path member 12 described above, and also communicates with the ink tank via a tube. For example, ink in the ink tank flows into the common flow path 121 via the tube and the four front openings 191, and returns to the ink tank via the four rear openings 191 and the tube.

[0021] As shown in FIGS. 4, 6 and 8, the actuator member 13 is disposed on the upper surface 12X of the flow path member 12 so as to cover the plurality of pressure chambers 12P.

[0022] 8, the actuator member 13 includes a piezoelectric body 40 including four piezoelectric layers 41 to 44 stacked in the vertical direction, a plurality of driving electrodes 51 arranged on the upper surface of the piezoelectric layer 41, a high-potential electrode 52 arranged on the upper surface of the piezoelectric layer 42, and a low-potential electrode 53 arranged on the upper surface of the piezoelectric layer 44. The driving electrode 51 corresponds to the "first electrode" of the present invention, the high-potential electrode 52 corresponds to the "second electrode" of the present invention, and the low-potential electrode 53 corresponds to the "third electrode" of the present invention. Both the high-potential electrode 52 and the low-potential electrode are spaced apart from the driving electrode 51 in the vertical direction.

[0023] 7, the drive electrode 51 includes a main portion 51A that overlaps with the pressure chamber 12P in the vertical direction, and an extension portion 51B that extends from the main portion 51A to a position where it does not overlap with the pressure chamber 12P in the vertical direction. The extension portion 51B extends left or right from the main portion 51A. As will be described later, the extension portion 51B is electrically connected to the COF 14 via a contact 149 (see FIG. 5).

[0024] 10, in addition to a plurality of drive electrodes 51, high potential portions 54, low potential portions 55, and auxiliary electrode portions 56 are arranged on the upper surface of the piezoelectric layer 41. The plurality of drive electrodes 51 are arranged in a central region excluding the peripheral portions of the piezoelectric layer 41. The sets of high potential portions 54, low potential portions 55, and auxiliary electrode portions 56 are arranged at the left and right ends of the piezoelectric layer 41, sandwiching the central region in the left-right direction.

[0025] The high potential portion 54 includes a plurality of electrodes 54A arranged in the front-rear direction. The low potential portion 55 includes a plurality of electrodes 55A arranged in the front-rear direction. The auxiliary electrode portion 56 includes a plurality of electrodes 56A and 56B arranged in the front-rear direction. As described below, the electrodes 54A, 55A, 56A, and 56B are electrically connected to the COF 14 via contacts 81 and 82 (see FIGS. 15 and 17) and the like.

[0026] 11 , the high-potential electrode 52 includes a mesh portion 521 that overlaps with the multiple driving electrodes 51 in the up-down direction, and an outer peripheral portion 522 that connects the outer peripheral edges of the mesh portion 521. The mesh portion 521 is formed in a mesh shape by providing multiple holes, i.e., missing portions 527, in the electrode. The mesh portion 521 is disposed in the central region of the piezoelectric layer 42, excluding the peripheral edge portion. The outer peripheral portion 522 includes a portion that extends in the front-to-rear direction to connect the left outer peripheral edges of the mesh portion 521, a portion that extends in the front-to-rear direction to connect the right outer peripheral edges of the mesh portion 521, a portion that extends in the left-to-right direction to connect the front outer peripheral edges of the mesh portion 521, and a portion that extends in the left-to-right direction to connect the rear outer peripheral edges of the mesh portion 521.

[0027] In the outer peripheral portion 522, the portions located at the rear of the left end and the front of the right end of the piezoelectric layer 42 overlap the high potential portion 54 (see FIG. 10) in the vertical direction. The high potential electrode 52 is electrically connected to a plurality of electrodes 54A of the high potential portion 54 via through holes 41X formed in the piezoelectric layer 41. The through holes 41X are formed in positions facing the electrodes 54A, and the interiors thereof are filled with a conductive material.

[0028] As shown in FIG. 11, in addition to the high potential electrode 52, a low potential portion 57 and a floating electrode portion 61 are arranged on the upper surface of the piezoelectric layer .

[0029] The low potential portion 57 is disposed in front of the left end and in the rear of the right end of the piezoelectric layer 42, and includes a plurality of electrodes 57A aligned in the front-to-rear direction. Each electrode 57A overlaps with each electrode 55A (see FIG. 10) of the low potential portion 55 in the vertical direction, and is electrically connected to each electrode 55A via a through hole 41Y formed in the piezoelectric layer 41. The through hole 41Y is formed in a position facing the electrode 55A, and is filled with a conductive material.

[0030] The floating electrode portion 61 is disposed approximately at the center in the front-to-rear direction of each of the left and right ends of the piezoelectric layer 42, and is sandwiched in the front-to-rear direction between the outer peripheral portion 522 and the low potential portion 57. The floating electrode portion 61 includes two electrodes 61A aligned in the front-to-rear direction. The electrode 61A is not electrically connected to either electrode, and no potential is applied to the electrode 61A.

[0031] As shown in FIG. 12, a low potential portion 58 and a floating electrode portion 62 are disposed on the upper surface of the piezoelectric layer 43.

[0032] The low potential portion 58 is disposed in front of the left end and in the rear of the right end of the piezoelectric layer 43, and includes a plurality of electrodes 58A aligned in the front-to-rear direction. Each electrode 58A overlaps with each electrode 57A (see FIG. 11) of the low potential portion 57 in the vertical direction, and is electrically connected to each electrode 57A via a through hole 42Y formed in the piezoelectric layer 42. The through hole 42Y is formed in a position facing the electrode 57A, and is filled with a conductive material.

[0033] The floating electrode portion 62 is disposed at the rear of the left end and at the front of the right end of the piezoelectric layer 43, and includes a plurality of electrodes 62A arranged in the front-to-rear direction. The electrodes 62A are not electrically connected to any of the electrodes, and no potential is applied to them.

[0034] 13 , the low-potential electrode 53 includes a mesh portion 531 that overlaps with the multiple drive electrodes 51 in the up-down direction, and an outer peripheral portion 532 that connects the outer peripheral edges of the mesh portion 531. The mesh portion 531 is formed in a mesh shape by providing multiple holes, i.e., missing portions 537, in the electrode. The mesh portion 531 is disposed in the central region of the piezoelectric layer 44, excluding the peripheral edge portion. The outer peripheral portion 532 includes a portion that extends in the front-to-rear direction to connect the left outer peripheral edges of the mesh portion 531, a portion that extends in the front-to-rear direction to connect the right outer peripheral edges of the mesh portion 531, a portion that extends in the left-to-right direction to connect the front outer peripheral edges of the mesh portion 531, and a portion that extends in the left-to-right direction to connect the rear outer peripheral edges of the mesh portion 531.

[0035] In the outer peripheral portion 532, the portions located in front of the left end and in the rear of the right end of the piezoelectric layer 44 overlap the low potential portion 58 (see FIG. 12) in the vertical direction. The low potential electrode 53 is electrically connected to a plurality of electrodes 58A of the low potential portion 58 via through holes 43Z formed in the piezoelectric layer 43. The through holes 43Z are formed in positions facing the electrodes 58A, and the insides thereof are filled with a conductive material.

[0036] As shown in FIG. 13, in addition to the low potential electrode 53, a floating electrode portion 63 is arranged on the upper surface of the piezoelectric layer 44.

[0037] The floating electrode portion 63 is disposed at the rear of the left end and at the front of the right end of the piezoelectric layer 44, and includes a plurality of electrodes 63A arranged in the front-rear direction. The electrodes 63A are not electrically connected to any of the electrodes, and no potential is applied to them.

[0038] As shown in FIG. 9 , a portion of the piezoelectric layer 41 sandwiched in the vertical direction between the main portion 51A of the driving electrode 51 and the mesh portion 521 of the high-potential electrode 52 is referred to as a first active portion 91. A portion of the piezoelectric layers 41 to 43 sandwiched in the vertical direction between the main portion 51A of the driving electrode 51 and the mesh portion 531 of the low-potential electrode 53 is referred to as a second active portion 92. The first active portion 91 is polarized mainly upward, and the second active portion 92 is polarized mainly downward. The actuator member 13 has an actuator portion 90 for each pressure chamber 12P, which is composed of one first active portion 91 and two second active portions 92. Each actuator portion 90 overlaps with the corresponding pressure chamber 12P in the vertical direction.

[0039] Here, the operation of the actuator section 90 will be described.

[0040] Before the printer 100 starts a recording operation, as shown in Fig. 9(a), a low potential (GND potential) is applied to each drive electrode 51. At this time, the potential difference between the drive electrode 51 and the high potential electrode 52 generates an upward electric field in the first active portion 91 that is equal to the polarization direction of the first active portion 91, causing the first active portion 91 to contract in a direction perpendicular to the up-down direction. As a result, the portion of the piezoelectric body 40 that overlaps with the pressure chamber 12P in the up-down direction is bent so as to convex toward the pressure chamber 12P. At this time, the volume of the pressure chamber 12P is smaller than when the piezoelectric body 40 is flat.

[0041] When the printer 100 starts a recording operation and ejects ink from a nozzle 123, the potential of the drive electrode 51 corresponding to that nozzle 123 is first switched from low potential (GND potential) to high potential (VDD potential), as shown in FIG. 9(b). At this time, the potential difference between the drive electrode 51 and the high-potential electrode 52 disappears, thereby eliminating the contraction of the first active section 91. Meanwhile, the potential difference between the drive electrode 51 and the low-potential electrode 53 generates a downward electric field in the second active section 92, which is equal to the polarization direction of the second active section 92. This causes the second active section 92 to contract in a direction perpendicular to the vertical direction. However, the second active section 92 has the function of suppressing crosstalk and therefore contributes little to the deformation of the actuator section 90. In other words, at this time, the portion of the piezoelectric element 40 that vertically overlaps with the pressure chamber 12P does not bend convexly in the direction away from the pressure chamber 12P, but remains flat. This increases the volume of the pressure chamber 12P compared to FIG. 8(a). Crosstalk refers to a phenomenon in which pressure fluctuations in a pressure chamber 12P caused by deformation of the actuator section 90 are transmitted to other pressure chambers 12P adjacent to the pressure chamber 12P in the front-rear direction.

[0042] 9(a), the potential of the drive electrode 51 is switched from a high potential (VDD potential) to a low potential (GND potential). At this time, the potential difference between the drive electrode 51 and the low potential electrode 53 disappears, and the contraction of the second active portion 92 is canceled. Meanwhile, the potential difference between the drive electrode 51 and the high potential electrode 52 is generated, and an upward electric field equal to the polarization direction of the first active portion 91 is generated in the first active portion 91, and the first active portion 91 contracts in a direction perpendicular to the up-down direction. As a result, the portion of the piezoelectric body 40 that overlaps with the pressure chamber 12P in the up-down direction bends so as to convex toward the pressure chamber 12P. At this time, the volume of the pressure chamber 12P decreases significantly, and a large pressure is applied to the ink in the pressure chamber 12P, and ink is ejected from the nozzle 123.

[0043] As shown in Fig. 4, the COF 14 includes a connection portion 14X disposed on the upper surface 13X of the actuator member 13 via a plurality of contacts 149, 81, and 82 (see Figs. 5, 15, and 17), and two folded portions 14Y drawn from one end 14X1 and the other end 14X2 of the connection portion 14X in the front-to-rear direction and folded back upward. Each of the two folded portions 14Y includes a vertical portion extending upward from the one end 14X1 or the other end 14X2 of the connection portion 14X, and a horizontal portion extending rearward or forward from the upper end of the vertical portion toward the center of the head 10 in the front-to-rear direction. Of the two folded portions 14Y, a driver IC 15A is disposed on the upper surface of the horizontal portion of the front folded portion 14Y, and a driver IC 15B is disposed on the upper surface of the horizontal portion of the rear folded portion 14Y.

[0044] 5, the COF 14 has a rectangular substrate 141 that defines the outer shape of the COF 14. The substrate 141 is provided across the connection portion 14X and the two folded portions 14Y. The substrate 141 may be made of a flexible and insulating material such as polyimide.

[0045] COF 14 further includes wiring 142 (see FIG. 5) electrically connected to drive electrode 51 via contact 149, wiring 144 (see FIGS. 14 and 15) electrically connected to electrode 54A via contact 81, wiring 145 (see FIGS. 16 and 17) electrically connected to electrode 55A via contact 82, and wiring electrically connected to electrodes 56A and 56B (see FIG. 10) via contacts. These wirings are arranged on substrate 141.

[0046] Under the control of the control device 8, the driver ICs 15A and 15B selectively apply either a high potential (VDD potential) or a low potential (GND potential) to the drive electrode 51 via wiring 142, apply a high potential (VDD potential) to the electrode 54A via wiring 144, and apply a low potential (GND potential) to the electrode 55A via wiring 145. The high potential (VDD potential) applied to the electrode 54A is applied to the high potential electrode 52, and the low potential (GND potential) applied to the electrode 55A is applied to the low potential electrode 53. Furthermore, under the control of the control device 8, the driver ICs 15A and 15B apply a high potential (VDD potential) to the electrode 56A via wiring of the COF 14, and apply a low potential (GND potential) to the electrode 56B via wiring of the COF 14.

[0047] In this way, the COF 14 is electrically connected to the actuator member 13 via the plurality of contacts 149, 81, and 82, and supplies voltage to the plurality of actuator portions 90 through the plurality of contacts 149, 81, and 82.

[0048] Contact 81 (see FIG. 15) is electrically connected to high potential electrode 52 via electrode 54A. Contact 82 (see FIG. 17) is electrically connected to low potential electrode 53 via electrode 55A. Contact 81 corresponds to the "first contact" of the present invention, and contact 82 corresponds to the "second contact" of the present invention. Alternatively, contact 82 corresponds to the "first contact" of the present invention, and contact 81 corresponds to the "second contact" of the present invention.

[0049] The contacts 81 are arranged at random intervals in the front-rear direction as shown in FIG. 15 along the rear portion of the left end and the front portion of the right end of the piezoelectric layer 41 (see FIG. 14), i.e., along the rear left outer periphery 522 and the front right outer periphery 522 of the high-potential electrode 52 (see FIG. 11). These contacts 81 include contacts with short lengths in the front-rear direction and contacts with long lengths in the front-rear direction. For example, in FIG. 15, the length along the outer periphery of the leftmost contact 81 is a first length, and the length along the outer periphery of the second leftmost contact 81 is a second length that is longer than the first length. The leftmost contact 81 is arranged across two electrodes 54A lined up in the front-rear direction, and the second leftmost contact 81 is arranged across four electrodes 54A lined up in the front-rear direction. In this way, multiple contacts 81 with different lengths in the front-rear direction are arranged at random intervals in the front-rear direction along the outer periphery 522. The plurality of electrodes 54A includes electrodes with contacts 81 and electrodes without contacts 81. There are regions where the electrodes 54A with contacts 81 are continuously lined up, and there are also regions where the electrodes 54A without contacts 81 are continuously lined up.

[0050] The contacts 82 are arranged at random intervals in the front-rear direction as shown in FIG. 17 along the front portion of the left end and the rear portion of the right end of the piezoelectric layer 41 (see FIG. 16), i.e., along the front-left outer periphery 532 and the rear-right outer periphery 532 of the low potential electrode 53 (see FIG. 13). These contacts 82 include contacts having short lengths in the front-rear direction and contacts having long lengths in the front-rear direction. For example, in FIG. 17, the length along the outer periphery of the leftmost contact 82 is a first length, and the length along the outer periphery of the second leftmost contact 82 is a second length that is longer than the first length. The leftmost contact 82 is arranged across two electrodes 55A lined up in the front-rear direction, and the second leftmost contact 82 is arranged across four electrodes 55A lined up in the front-rear direction. In this way, multiple contacts 82 having different lengths in the front-rear direction are arranged at random intervals in the front-rear direction along the outer periphery 532. The plurality of electrodes 55A includes electrodes on which contacts 82 are arranged and electrodes on which contacts 82 are not arranged. There are regions where electrodes 54A on which contacts 82 are arranged are continuously lined up, and there are also regions where electrodes 54A on which contacts 82 are not arranged are continuously lined up.

[0051] In the connection portion 14X (see FIG. 4), wirings 142, 144, and 145 are arranged on the lower surface of the base material 141 (see FIGS. 15 and 17). Furthermore, a coating film 143 is arranged on almost the entire lower surface of the base material 141, except for the portions where the contact points 149, 81, and 82 of the wirings 142, 144, and 145 are joined. The coating film 143 covers the wirings 142, 144, and 145.

[0052] 14, two wires 144 are arranged in parallel along the rear part of the left end and the front part of the right end of the piezoelectric layer 41, i.e., along the rear left outer periphery 522 and front right outer periphery 522 of the high potential electrode 52 (see FIG. 11). The two wires 144 extend in the front-rear direction so as to overlap with the right end and left end of the electrode 54A in the up-down direction, respectively, and are spaced apart from each other in the left-right direction.

[0053] 16, two wires 145 are arranged in parallel along the front left end and rear right end of the piezoelectric layer 41, i.e., along the front left outer periphery 532 and rear right outer periphery 532 of the low potential electrode 53 (see FIG. 13). The two wires 145 are arranged at positions overlapping the right and left ends of the electrode 55A in the vertical direction, respectively, and are spaced apart from each other in the horizontal direction.

[0054] As shown in Fig. 4, the actuator member 13 and the COF 14 are disposed within the frame 19. The pressing member 18, the support member 16, and the circuit board 17 are disposed in the space surrounded by the connection portion 14X and the two folded portions 14Y of the COF 14. The pressing member 18, the support member 16, and the circuit board 17 are disposed above the connection portion 14X. The vertical portion of the folded portion 14Y is disposed along the side surface of the pressing member 18.

[0055] 4, the lower surface of the pressing member 18 is disposed with a gap between the upper surface 13X of the actuator member 13, i.e., the region 13R on the upper surface of the piezoelectric layer 41 where the driving electrode 51 (see FIG. 10) is disposed, and the connection portion 14X connected to the region 13R. The peripheral portion of the lower surface of the pressing member 18 contacts the connection portion 14X and presses the connection portion 14X downward toward the actuator member 13.

[0056] As shown in FIG. 4, the support member 16 is supported from below by a pressing member 18, and supports three circuit boards 17 on the lower surface.

[0057] The circuit board 17 is disposed in a recess provided on the upper surface of the pressing member 18 and is electrically connected to the COF 14.

[0058] A sealant 20 is disposed along the inner peripheral edge of the frame 19. The sealant 20 is disposed so as to extend in the left-right direction along one end 14X1 and the other end 14X2 in the front-rear direction of the connection portion 14X, and is also disposed so as to extend in the front-rear direction along one end 14X3 and the other end 14X4 in the left-rear direction of the connection portion 14X (see FIG. 6). The sealant 20 isolates the space between the connection portion 14X and the actuator member 13 from the external space. This prevents ion migration between the drive electrodes 51 caused by moisture in the air entering the space. The sealant 20 may be made of a non-conductive material such as fluororesin.

[0059] As described above, according to this embodiment, voltage drops can be prevented by having at least one of the high potential electrode 52 and the low potential electrode 53 have the mesh portions 521, 531 (see FIGS. 11 and 13). Furthermore, by arranging at least one of the contacts 81, 82 at random intervals (see FIGS. 15 and 17), the charge / discharge path lengths of the multiple actuator elements 90 are adjusted to be equal, and variations in the operation of the actuator elements 90 are less likely to occur.

[0060] Since both the high potential electrode 52 and the low potential electrode 53 have the mesh portions 521, 531 (see FIGS. 11 and 13), voltage drops can be prevented more reliably. In addition, since both the contacts 81, 82 are arranged at random intervals (see FIGS. 15 and 17), variations in the operation of the actuator element 90 are even less likely to occur.

[0061] A plurality of contacts 81 (see FIG. 15) having different lengths in the front-rear direction are arranged at random intervals in the front-rear direction along the outer circumferential portion 522. By making the lengths in the front-rear direction different between the plurality of contacts 81 in this way, the charge / discharge path lengths in the plurality of actuator units 90 are more reliably adjusted to be equal, and variation in the operation of the actuator units 90 is less likely to occur. The same effect as above can be obtained by arranging a plurality of contacts 82 (see FIG. 17) having different lengths in the front-rear direction at random intervals in the front-rear direction along the outer circumferential portion 532.

[0062] The wiring 144 (see FIG. 14 ), which is electrically connected to the high-potential electrode 52 via the contact 81 and the electrode 54A, is arranged in parallel along the outer periphery. In this case, depending on the arrangement of the contact 81, it is possible to provide a portion where the contact 81 is electrically connected to both of the parallel wirings 144 or a portion where the contact 81 is electrically connected to one of the parallel wirings 144, thereby changing the contact area between the contact 81 and the wiring 144. This more reliably adjusts the charge / discharge path lengths of the multiple actuator elements 90 to be equal, making it less likely that variations in the operation of the actuator elements 90 will occur. The same effect as above can also be achieved by arranging the wiring 145 (see FIG. 16 ), which is electrically connected to the low-potential electrode 53 via the contact 82 and the electrode 55A, in parallel along the outer periphery.

[0063] By providing the sealant 20 (see FIG. 4) that isolates the space between the connection portion 14X and the actuator member 13 from the external space, it is possible to prevent ion migration between the drive electrodes 51. In this case, the sealant 20 may enter the space between the connection portion 14X and the actuator member 13 through the relatively wide gaps between the randomly arranged contacts 81 (see FIG. 15), but the sealant 20 can be stored between the parallel wirings 144, preventing the sealant 20 from entering. The same effect as above can be obtained by using the randomly arranged contacts 82 and the corresponding wirings 145.

[0064] By providing a coating film 143 that is placed on the underside of the substrate 141 at the connection portion 14X and covers the multiple wirings 142, 144, and 145, the space between the connection portion 14X and the actuator member 13 into which the sealing material 20 can penetrate is reduced, making it possible to more reliably prevent the sealing material 20 from penetrating.

[0065] Second Embodiment In the first embodiment, the wiring 144 electrically connected to the electrodes 54A is arranged in parallel along the outer periphery (see FIG. 14). In contrast to this, in the second embodiment, the wiring 244 electrically connected to the electrodes 54A has a mesh-like portion 244X arranged along the outer periphery (see FIG. 18). The wiring 244 includes a portion that overlaps the entirety of the multiple electrodes 54A in the vertical direction, and the above-mentioned portion 244X. The portion 244X is formed in a mesh-like shape so as to overlap only a portion of each electrode 54A in the vertical direction.

[0066] According to this embodiment, the contact area between the contacts 81 and the mesh portion 244X can be changed by changing the arrangement of the contacts 81. This more reliably adjusts the charge / discharge path lengths of the multiple actuator elements 90 to be equal, reducing the likelihood of variations in the operation of the actuator elements 90. Furthermore, the sealant 20 can be stored in the mesh portion 244X, preventing the sealant 20 from entering.

[0067] The wiring 145 (see FIG. 16) electrically connected to the electrode 55A may also have a mesh-like configuration instead of being arranged in parallel.

[0068] <Modification> Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design modifications are possible within the scope of the claims.

[0069] In the above-described embodiment, a high potential (VDD potential) is applied to the second electrode and a low potential (GND potential) is applied to the third electrode, but this is not limiting. For example, a low potential (GND potential) may be applied to the second electrode and a high potential (VDD potential) may be applied to the third electrode.

[0070] Only one of the second electrode and the third electrode may have a mesh portion and an outer periphery, and in this case, the second contact point corresponding to the other of the second electrode and the third electrode may be arranged in any manner.

[0071] The first contacts may have a constant length along the periphery, and similarly, the second contacts may have a constant length along the periphery.

[0072] The number and arrangement of the first contacts and the number and arrangement of the second contacts can be changed in various ways so long as the charge / discharge path lengths are equal in the plurality of actuator elements.

[0073] The wiring electrically connected to one of the second and third electrodes via the plurality of first contacts may be three or more in number and arranged in parallel along the outer periphery of one of the electrodes. Similarly, the wiring electrically connected to the other of the second and third electrodes via the plurality of second contacts may be three or more in number and arranged in parallel along the outer periphery of the other electrode.

[0074] The sealing material and the coating film may be omitted.

[0075] The flow path member is not limited to a serial type, but may be a line type.

[0076] The object onto which the liquid is ejected from the nozzles is not limited to paper, but may be, for example, cloth, a substrate, a plastic member, or the like.

[0077] The liquid ejected from the nozzles is not limited to ink, but may be any liquid (for example, a treatment liquid that aggregates or precipitates components in the ink, etc.).

[0078] The present invention is not limited to printers, but can also be applied to facsimiles, copiers, multifunction machines, etc. The present invention can also be applied to liquid ejection devices used for purposes other than image recording (for example, liquid ejection devices that eject conductive liquid onto a substrate to form a conductive pattern). [Explanation of symbols]

[0079] 10 head (liquid ejection head) 12 Flow path member 12P pressure chamber 12X top 13 Actuator member 14 COF (wiring materials) 14X Connection Part 14X1,14X3 One end (end) 14X2, 14X4 other end (end) 141 Base material 144,145;244 wiring 244X Reticulated part 143 Coating membrane 20 Encapsulating material 40 Piezoelectric 41-44 Piezoelectric layer 51 driving electrode (first electrode) 52 High potential electrode (second electrode) 521 Reticulum 522 Outer periphery 53 Low potential electrode (3rd electrode) 531 Reticulum 532 Outer periphery 81, 82, 149 contacts 90 Actuator section 91 1st active part 92 2nd active part

Claims

1. a flow path member having an upper surface to which a plurality of pressure chambers are opened; an actuator member disposed on the upper surface of the flow path member so as to cover the plurality of pressure chambers, the actuator member having a plurality of actuator portions that overlap with the plurality of pressure chambers in the vertical direction; a wiring member electrically connected to the actuator member via a plurality of contacts and supplying a voltage to the plurality of actuator units through the plurality of contacts; The actuator member a piezoelectric body including a plurality of piezoelectric layers stacked in the vertical direction; a plurality of first electrodes overlapping the plurality of pressure chambers in the vertical direction; a second electrode spaced apart from the plurality of first electrodes in the vertical direction; a third electrode spaced apart from the plurality of first electrodes in the vertical direction, the piezoelectric body has a first active portion sandwiched between the first electrode and the second electrode in the vertical direction, and a second active portion sandwiched between the first electrode and the third electrode in the vertical direction, each of the plurality of actuator elements includes the first active portion and the second active portion; At least one of the second electrode and the third electrode has a mesh portion overlapping with the plurality of first electrodes in the up-down direction and an outer periphery portion connecting outer peripheries of the mesh portion, A liquid ejection head, characterized in that a plurality of first contacts electrically connected to the one of the plurality of contacts are arranged at random intervals along the outer periphery of the one.

2. Both the second electrode and the third electrode have the mesh portion and the outer periphery portion, 2. A liquid ejection head as described in claim 1, characterized in that among the plurality of contacts, a plurality of second contacts electrically connected to the other of the second electrode and the third electrode are arranged at random intervals along the outer periphery of the other.

3. 2. The liquid ejection head according to claim 1, wherein the plurality of first contacts include a contact whose length along the outer periphery is a first length and a contact whose length along the outer periphery is a second length longer than the first length.

4. the wiring member has wiring electrically connected to the one of the first contacts via the plurality of first contacts, 2. The liquid ejection head according to claim 1, wherein a plurality of said wirings are arranged in parallel along said one outer periphery.

5. the wiring member has wiring electrically connected to the one of the first contacts via the plurality of first contacts, 2. The liquid ejection head according to claim 1, wherein the wiring has a mesh-like portion disposed along the one outer periphery.

6. the wiring member has a connection portion connected to the upper surface of the actuator member via the plurality of contacts, the connection portion having the wiring disposed therein; 6. The liquid ejection head according to claim 4, further comprising a sealant disposed along an end of the connecting portion, for isolating a space between the connecting portion and the actuator member from an external space.

7. the wiring member has a base material disposed across the connection portion, the wiring is disposed on the lower surface of the base material; 7. The liquid ejection head according to claim 6, further comprising a coating film disposed on the lower surface of said base material and covering said plurality of wirings.

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