Liquid discharge head

Abstract

To suppress deformation damage of an actuator part while increasing a width of a branch part.SOLUTION: A head has an actuator member. The actuator member includes a plurality of individual electrodes 52A, a branch part 523, and a stem. A nozzle 15 included in a first individual channel row 19R1 and a nozzle 15 included in a second individual channel row 19R2 are arranged between a pressure chamber 10 included in the first individual channel row 19R1 and a pressure chamber 10 included in the second individual channel row 19R2 in a second direction D2. The branch part 523 is disposed between the pressure chamber 10 included in the first individual channel row 19R1 and the pressure chamber 10 included in the second individual channel row 19R2 in the second direction D2, and overlaps the nozzle 15 included in the first individual channel row 19R1 and the nozzle 15 included in the second individual channel row 19R2 in a third direction D3.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a liquid ejection head that ejects liquid.

Background Art

[0002] Patent Document 1 discloses a head (liquid ejection head) including a flow path unit (flow path member) in which a plurality of pressure chambers are formed and a piezoelectric actuator (actuator member) disposed on the surface of the flow path unit. The piezoelectric actuator includes a plurality of individual parts (individual electrodes) respectively corresponding to the plurality of pressure chambers, a plurality of branch parts connecting the plurality of individual parts, and a trunk part connecting the plurality of branch parts. A contact with a COF (power supply part) is provided on the trunk part.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The trunk part supplies electric charges from the power supply part to the individual electrodes via the plurality of branch parts. Since a plurality of individual electrodes are connected to the branch parts and a large amount of electric charges flow to supply the plurality of individual electrodes with electric charges, the branch parts are likely to generate a large amount of heat.

[0005] To solve the above problems, the inventor of the present invention considered widening the width of the branch part (the length in the direction orthogonal to the extending direction of the branch part). However, when the width of the branch part is widened, the branch part is likely to overlap with the pressure chamber and also likely to overlap with the drive electrode (first electrode) of the actuator member in the direction (third direction) orthogonal to the surface of the flow path member. When the width of the branch part is widened in this way, when driving the actuator member, in the portion overlapping with the pressure chamber, the portion of the piezoelectric layer sandwiched between the branch part and the drive electrode in the third direction is deformed, and the deformation inhibits the deformation of the actuator part.

[0006] Therefore, an object of the present invention is to provide a liquid ejection head capable of suppressing inhibition of deformation of an actuator unit while widening the width of a branch portion.

Means for Solving the Problems

[0007] The liquid ejection head of the present invention is a flow path member in which a plurality of individual flow paths each including a nozzle and a pressure chamber communicating with the nozzle are formed, and a plurality of individual flow path rows each having the plurality of individual flow paths arranged in a first direction are arranged in a second direction orthogonal to the first direction. And an actuator member disposed on the surface of the flow path member and having a plurality of actuator portions overlapping in a third direction orthogonal to the surface of each of the pressure chambers of the plurality of individual flow paths. The actuator member includes a plurality of individual electrodes constituting the plurality of actuator portions, a branch portion extending along the first direction and connecting the plurality of individual electrodes, and a trunk portion connected to the branch portion and provided with a contact point with a power supply portion. Among the plurality of individual flow path rows, the nozzle included in the first individual flow path row and the nozzle included in the second individual flow path row adjacent to the first individual flow path row are arranged in the second direction between the pressure chamber included in the first individual flow path row and the pressure chamber included in the second individual flow path row. The branch portion is arranged in the second direction between the pressure chamber included in the first individual flow path row and the pressure chamber included in the second individual flow path row, and overlaps with the nozzle included in the first individual flow path row and the nozzle included in the second individual flow path row in the third direction.

Effects of the Invention

[0008] According to the liquid ejection head of the present invention, in the second direction, the pressure chambers included in the first individual flow path row are farther from the pressure chambers included in the second individual flow path row than the nozzles included in the first individual flow path row, and the pressure chambers included in the second individual flow path row are farther from the pressure chambers included in the first individual flow path row than the nozzles included in the second individual flow path row. That is, the region between the pressure chambers included in the first individual flow path row and the pressure chambers included in the second individual flow path row of the flow path member becomes relatively large in the second direction, and in this region, the branches are arranged so as to overlap the nozzles included in the first individual flow path row and the nozzles included in the second individual flow path row in the third direction. For this reason, it becomes possible to form the width (length in the second direction) of the branch portion wide. Moreover, since the branch portion does not overlap the pressure chamber in the third direction, it becomes possible to suppress the inhibition of the deformation of the actuator portion.

Brief Description of the Drawings

[0009]

Figure 1

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Figure 13

Mode for Carrying Out the Invention

[0010] <First Embodiment> First, referring to FIG. 1, the overall configuration of a printer 100 including a head 1 according to the first embodiment of the present invention will be described. In the following description, the first direction D1 and the second direction D2 are horizontal directions, and the third direction D3 is a vertical direction. Both the first direction D1 and the second direction D2 are orthogonal to the third direction D3. The first direction D1 is orthogonal to the second direction D2.

[0011] <Overall Configuration of the Printer> The printer 100 includes a housing 100A, a head unit 1X, a platen 3, a conveyance mechanism 4, and a control unit 5. The head unit 1X, the platen 3, the conveyance mechanism 4, and the control unit 5 are disposed within the housing 100A. Further, the printer 100 further includes buttons disposed on the outer surface of the housing 100A.

[0012] The length of the head unit 1X in the first direction D1 is longer than the length in the conveyance direction along the second direction D2 of the head unit 1X. The first direction D1 is the direction along the width of the paper 9. The head unit 1X is fixed to the housing 100A. The type of the head unit 1X is a line type.

[0013] The head unit 1X includes four heads 1. The four heads 1 are arranged in a staggered manner in the first direction D1. The length of the head 1 in the first direction D1 is longer than the length of the head 1 in the second direction D2.

[0014] The platen 3 is a plate along a plane orthogonal to the third direction D3 and is disposed below the head unit 1X. A sheet of paper 9 is supported on the upper surface of the platen 3.

[0015] The transport mechanism 4 has two roller pairs 4A and 4B disposed sandwiching the platen 3 in the second direction D2. When a transport motor (not shown) is driven under the control of the control unit 5, the roller pairs 4A and 4B rotate while sandwiching the sheet of paper 9, and the sheet of paper 9 is transported in the transport direction along the second direction D2.

[0016] The control unit 5 includes a CPU, a ROM, and a RAM. The CPU executes a recording process according to programs and data stored in the ROM and RAM based on data input from an external device or the above buttons. In the recording process, the control unit 5 controls the transport motor and the driver IC (both not shown) based on the input data, causing the transport mechanism 4 to transport the sheet of paper 9 and the head 1 to discharge ink onto the sheet of paper 9. Thereby, an image is recorded on the sheet of paper 9. The external device is, for example, a personal computer (PC).

[0017] <Head> As shown in FIG. 2, the head 1 has a flow path member 21 and an actuator member 22. Both the flow path member 21 and the actuator member 22 are rectangular in shape in a plane orthogonal to the third direction D3, with the length in the first direction D1 being longer than the length in the second direction D2.

[0018] <Flow path member> As shown in FIG. 4, the flow path member 21 is composed of six plates 31 to 36 laminated in the third direction D3.

[0019] The plate 31 has a plurality of pressure chambers 10 formed therein. The plate 32 has holes 12A and 13A formed therein for each pressure chamber 10. The holes 12A and 13A overlap with one end and the other end of the corresponding pressure chamber 10 in the second direction D2 and the third direction D3, respectively. The plate 33 has holes 12B formed for each hole 12A and holes 13B formed for each hole 13A. The plate 34 has holes 12C formed for each hole 12B and holes 13C formed for each hole 13B. The holes 12A and 12C overlap with one end and the other end of the corresponding hole 12B in the second direction D2 and the third direction D3, respectively. The holes 13A and 13C overlap with one end and the other end of the corresponding hole 13B in the second direction D2 and the third direction D3, respectively.

[0020] The plate 35 has holes 13D formed for each hole 13C. The holes 13D overlap with the corresponding holes 13C in the third direction D3. The plate 36 has a plurality of nozzles 15 formed therein. Each nozzle 15 overlaps with the hole 13D in the third direction D3 and communicates with each pressure chamber 10 via the first communication passage 13.

[0021] The first communication passage 13 is composed of holes 13A to 13D communicating with each other. The hole 13B has a portion 13B1 overlapping with the hole 13C in the third direction D3 and an extending portion 13B2 extending along the second direction D2 from the portion 13B1. The extending portion 13B2 is composed of a portion of the hole 13B that does not overlap with the hole 13C in the third direction D3. Further, the first communication passage 13 has a first portion 14A and a second portion 14B. The first portion 14A is composed of the holes 13C, 13D and the portion 13B1 and extends upward along the third direction from one end communicating with the nozzle 15. The second portion 14B is composed of the hole 13A and the extending portion 13B2 and extends along the second direction D2 from one end communicating with the first portion 14A. The other end of the second portion 14B communicates with the pressure chamber 10.

[0022] As shown in FIGS. 3 and 4, the hole 13B has a throttle portion 14C that restricts the flow rate of the liquid. The throttle portion 14C is formed in the extending portion 13B2 (the second portion 14B), and its flow path width is smaller than the flow path width of the first portion 14A. The flow path width referred to here is the width in the first direction D1. Both ends of the hole 13B in the second direction D2 in the present embodiment have a larger flow path width than the throttle portion 14C, but the hole 13B may have a constant flow path width over its entire length.

[0023] The plate 35 is further formed with 12 manifold flow paths 11. The manifold flow paths 11 are provided for each pressure chamber row 10R (see FIG. 2) composed of a plurality of pressure chambers 10 arranged in the first direction D1. Each manifold flow path 11 extends in the first direction D1 and communicates with a plurality of pressure chambers 10 belonging to the corresponding pressure chamber row 10R via the second communication path 12. The second communication path 12 is composed of holes 12A, 12B, and 12C that communicate with each other.

[0024] The flow path member 21 is formed with a plurality of individual flow paths 19. The plurality of individual flow paths 19 each include a nozzle 15, a first communication path 13 communicating with the nozzle 15, a pressure chamber 10 communicating with the first communication path 13, and a second communication path 12 communicating with the pressure chamber 10. As shown in FIG. 2, the individual flow paths 19 are arranged in the first direction D1 and constitute 12 individual flow path rows 19R. The 12 individual flow path rows 19R are arranged side by side in the second direction D2.

[0025] As shown in FIG. 3, the nozzles 15 included in the first individual flow path row 19R1 among the plurality of individual flow path rows 19R and the nozzles 15 included in the second individual flow path row 19R2 adjacent to the first individual flow path row 19R1 among the plurality of individual flow path rows 19R are arranged between the pressure chambers 10 included in the first individual flow path row 19R1 and the pressure chambers 10 included in the second individual flow path row 19R2 in the second direction D2. That is, as shown in FIG. 2, among the 12 individual flow path rows 19R, in the 10 individual flow path rows 19R excluding the two individual flow path rows 19R located at both ends in the second direction D2, the nozzles 15 included in the two rows of individual flow path rows 19R formed by sequentially taking two by two from the left end in the second direction D2 are located between the pressure chambers 10 included in the two rows of individual flow path rows 19R in the second direction D2. The first individual flow path row 19R1 and the second individual flow path row 19R2 correspond to the two rows of individual flow path rows 19R described above.

[0026] On the upper surface of the plate 31 (the surface 21A of the flow path member 21), two ink supply ports 8 are formed in a region where the actuator member 22 is not arranged (see FIG. 2). Each ink supply port 8 communicates with an ink cartridge (not shown) via a tube. Further, the two ink supply ports 8 communicate with the 12 manifold flow paths 11. The ink supplied from the ink cartridge to each ink supply port 8 via the tube is supplied to the 12 manifold flow paths 11. From each manifold flow path 11, ink is supplied to the plurality of pressure chambers 10 belonging to each pressure chamber row 10R via the second communication path 12. Then, as will be described later, when the actuator member 22 is driven, pressure is applied to the ink in the pressure chamber 10, and the ink is discharged from the nozzle 15 through the first communication path 13.

[0027] <Actuator member> As shown in FIG. 4, the actuator member 22 is arranged on the surface 21A of the flow path member 21. The actuator member 22 has a piezoelectric body 40 including three piezoelectric layers 41 to 43 and an electrode body 70 including three electrode layers 71 to 73 arranged on the upper surfaces of the piezoelectric layers 41 to 43.

[0028] The three piezoelectric layers 41 to 43 are each made of a piezoelectric material mainly composed of lead zirconate titanate or the like, and are laminated in the third direction D3. The piezoelectric layer 42 is disposed between the piezoelectric layer 43 and the piezoelectric layer 41.

[0029] The piezoelectric layer 43 is disposed on the upper surface of the plate 31 (the surface 21A of the flow path member 21), and covers all the pressure chambers 10 formed in the plate 31.

[0030] Among the three electrode layers 71 to 73, the electrode layer 71 disposed on the upper surface of the piezoelectric layer 41 (the surface on the opposite side of the piezoelectric layer 42 of the piezoelectric layer 41 in the third direction D3) includes a plurality of drive electrodes 51, two high potential portions 54, and two low potential portions 55 as shown in FIG. 7. The electrode layer 71 corresponds to the "first electrode layer" of the present invention.

[0031] The drive electrodes 51 are disposed corresponding to the pressure chambers 10 as shown in FIG. 3. The drive electrodes 51 have a main portion 51A and a protruding portion 51B. The main portion 51A overlaps with substantially the entire area of the corresponding pressure chamber 10 in the third direction D3. The protruding portion 51B protrudes from the main portion 51A in the second direction D2 and does not overlap with the corresponding pressure chamber 10 in the third direction D3. A contact electrically connected to a Chip On Film (COF: not shown) is provided on the protruding portion 51B. A driver IC (not shown) mounted on the COF supplies a drive signal individually to each drive electrode 51 via the wiring of the COF under the control of the control unit 5, and selectively applies either a high potential (VDD potential) or a low potential (GND potential). The high potential corresponds to the "first potential" of the present invention, the low potential corresponds to the "second potential" of the present invention, the drive electrode 51 corresponds to the "first electrode" of the present invention. The COF corresponds to the "power supply unit" of the present invention.

[0032] As shown in FIG. 7, the plurality of drive electrodes 51 are arranged in the first direction D1, and constitute a plurality of drive electrode rows 51R corresponding to the respective individual flow path rows 19R (see FIG. 2). The plurality of drive electrode rows 51R are arranged side by side in the second direction D2.

[0033] The two high potential portions 54 are respectively disposed on one side (the upper side in FIG. 7) of the piezoelectric layer 41 in the first direction D1 at one end (the left end in FIG. 7) and the other end (the right end in FIG. 7) of the piezoelectric layer 41 in the second direction D2. The two low potential portions 55 are respectively disposed on the other side (the lower side in FIG. 7) of the piezoelectric layer 41 in the first direction D1 at one end (the left end in FIG. 7) and the other end (the right end in FIG. 7) of the piezoelectric layer 41 in the second direction D2.

[0034] The two high potential portions 54 are each composed of a plurality of electrodes 54A spaced apart from each other in the first direction D1. The two low potential portions 55 are each composed of a plurality of electrodes 55A spaced apart from each other in the first direction D1. The electrodes 54A and 55A have substantially the same size and shape in a plane orthogonal to the third direction D3. The driver IC applies a high potential (VDD potential) to the electrode 54A and a low potential (GND potential) to the electrode 55A via the wiring of the COF under the control of the control unit. The electrode 54A is held at a high potential, and the electrode 55A is held at a low potential.

[0035] Among the three electrode layers 71 to 73, the electrode layer 72 disposed on the upper surface of the piezoelectric layer 42 (between the piezoelectric layer 41 and the piezoelectric layer 42 in the third direction D3) includes, as shown in FIG. 8, a high potential electrode 52, two low potential portions 56, two floating electrode portions 64, and a floating electrode portion 65. The electrode layer 72 corresponds to the "second electrode layer" of the present invention.

[0036] The high potential electrode 52 includes a trunk portion 521, seven branch portions 523 branched from the trunk portion 521, and a plurality of individual electrodes 52A branched from each branch portion 523. The high potential electrode 52 is held at a high potential (first potential) and corresponds to the "second electrode" of the present invention.

[0037] The stem 521 includes one extending portion 521A extending in the second direction D2 and two extending portions 521B respectively extending in the first direction D1. The extending portion 521A extends in the second direction D2 at one end (the upper end in FIG. 8) of the piezoelectric layer 42 in the first direction D1. Of the two extending portions 521B, one is connected to one end (the left end in FIG. 8) of the extending portion 521A in the second direction D2. Of the two extending portions 521B, the other is connected to the other end (the right end in FIG. 8) of the extending portion 521A in the second direction D2. The two extending portions 521B respectively extend from the connection portions with the extending portion 521A to the other side (the lower side in FIG. 8) in the first direction D1.

[0038] The two extending portions 521B respectively overlap with three electrodes 54A (see FIG. 7) of the high potential portion 54 in the third direction D3. The two extending portions 521B are respectively electrically connected to the three electrodes 54A through through-holes 41X (see FIG. 7) formed in the piezoelectric layer 41 and receive a high potential from the electrodes 54A. That is, contacts with a COF, which is a power supply unit, are provided on the two extending portions 521B. The high potential received by the two extending portions 521B is supplied to each individual electrode 52A through the branch portions 523.

[0039] The seven branch portions 523 each extend from the extending portion 521A to the other side in the first direction D1 (the lower side in FIG. 8) and are arranged side by side in the second direction D2. The width of each branch portion 523 is smaller than the width of the trunk portion 521 (extending portions 521A, 521B). As shown in FIG. 3, each branch portion 523 is disposed between the pressure chamber 10 included in the first individual flow path row 19R1 and the pressure chamber 10 included in the second individual flow path row 19R2 among the corresponding two rows of individual flow path rows 19R in the second direction D2. Also, each branch portion 523 is disposed at a distance from the pressure chamber 10 in the second direction D2 and does not overlap the pressure chamber 10 in the third direction D3. Further, each branch portion 523 overlaps a part of the nozzle 15 and the first communication path 13 included in the first individual flow path row 19R1 and a part of the nozzle 15 and the first communication path 13 included in the second individual flow path row 19R2 among the corresponding two rows of individual flow path rows 19R in the third direction D3. More specifically, each branch portion 523 overlaps not only the first portion 14A of the first communication path 13 but also a part of the second portion 14B in the third direction D3. Also, each branch portion 523 does not overlap the drive electrode 51 in the third direction D3.

[0040] The individual electrode 52A overlaps the central portion of the pressure chamber 10 in the first direction D1 and has a portion that overlaps the drive electrode 51 in the third direction D3 (see FIG. 5). The plurality of individual electrodes 52A are arranged in the first direction D1 and constitute a plurality of individual electrode rows 52R corresponding to each of the drive electrode rows 51R (see FIG. 7). The plurality of individual electrode rows 52R are arranged side by side in the second direction D2. The branch portion 523 connects the plurality of individual electrodes 52A that constitute each individual electrode row 52R.

[0041] The two low potential portions 56 are respectively disposed on the other side in the first direction D1 (the lower side in FIG. 8) of the piezoelectric layer 42 at one end (the left end in FIG. 8) and the other end (the right end in FIG. 8) of the piezoelectric layer 42 in the second direction D2. The two low potential portions 56 are each composed of two electrodes 56A and one electrode 56B that are spaced apart from each other in the first direction D1.

[0042] The two floating electrode portions 64 are respectively disposed between the extending portion 521B and the low potential portion 56 in the first direction D1 at one end (the left end in FIG. 8) and the other end (the right end in FIG. 8) of the piezoelectric layer 42 in the second direction D2. The two floating electrode portions 64 are each composed of a plurality of electrodes 64A spaced apart from each other in the first direction D1.

[0043] The floating electrode portion 65 is disposed at the other end (the lower end in FIG. 8) of the piezoelectric layer 42 in the first direction D1. The floating electrode portion 65 is composed of a plurality of electrodes 65A spaced apart from each other in the second direction D2. The electrodes 65A are substantially the same in size and shape on the plane orthogonal to the third direction D3 and are arranged at equal intervals in the second direction D2.

[0044] The electrode 56A of the low potential portion 56 and the electrode 64A of the floating electrode portion 64 are substantially the same in size and shape on the plane orthogonal to the third direction D3, and are arranged at equal intervals in the first direction D1 at each of one end (the left end in FIG. 8) and the other end (the right end in FIG. 8) of the piezoelectric layer 42 in the second direction D2. On the other hand, the electrode 56B of the low potential portion 56 is longer than the electrode 56A in the first direction D1.

[0045] The two electrodes 56A overlap with the two electrodes 55A (see FIG. 7) of the low potential portion 55 in the third direction D3. The two electrodes 56A are electrically connected to the two electrodes 55A through the through holes 41Y (see FIG. 7) formed in the piezoelectric layer 41 and receive a low potential from the electrodes 55A.

[0046] The electrode 56B overlaps with one electrode 55A (see FIG. 7) of the low potential portion 55 in the third direction D3. The electrode 56B is electrically connected to the one electrode 55A through the through hole 41Y (see FIG. 7) formed in the piezoelectric layer 41 and receives a low potential from the electrode 55A.

[0047] Each of the electrodes 64A and 65A of the floating electrode portions 64 and 65 is not electrically connected to any other electrode and no potential is applied thereto.

[0048] Of the three electrode layers 71 to 73, the electrode layer 73 disposed on the upper surface of the piezoelectric layer 43 (the surface on the opposite side of the piezoelectric layer 41 of the piezoelectric layer 42 in the third direction D3) includes a low-potential electrode 53, a high-potential portion 57, and two floating electrode portions 66 as shown in FIG. 9. The electrode layer 73 corresponds to the "third electrode layer" of the present invention.

[0049] The low-potential electrode 53 includes a trunk portion 531, six branch portions 533 branched from the trunk portion 531, and a plurality of individual electrodes 53A branched from each branch portion 533. The low-potential electrode 53 is held at a low potential (second potential) and corresponds to the "third electrode" of the present invention.

[0050] The trunk portion 531 includes one extending portion 531A extending in the second direction D2 and two extending portions 531B extending in the first direction D1, respectively. The extending portion 531A extends in the second direction D2 at the other end of the piezoelectric layer 43 in the first direction D1 (the lower end in FIG. 9). Of the two extending portions 531B, one is connected to one end of the extending portion 531A in the second direction D2 (the left end in FIG. 9). Of the two extending portions 531B, the other is connected to the other end of the extending portion 531A in the second direction D2 (the right end in FIG. 9). The two extending portions 531B each extend from the connection portion with the extending portion 531A to one side in the first direction D1 (the upper side in FIG. 9).

[0051] The two extending portions 531B each overlap with the three electrodes 55A of the low-potential portion 55 (see FIG. 7) and the three electrodes 56A, 56B of the low-potential portion 56 (see FIG. 8) in the third direction D3. The two extending portions 531B are each electrically connected to the three electrodes 56A, 56B of the low-potential portion 56 through through-holes 42Y formed in the piezoelectric layer 42 (see FIG. 8) and receive a low potential from the electrodes 56A, 56B. That is, each of the two extending portions 531B is provided with a contact point with a COF which is a power supply portion. The low potential received by the two extending portions 531B is supplied to each individual electrode 53A through the branch portion 533.

[0052] The six branch portions 533 each extend from the extending portion 531A to one side in the first direction A (the upper side in FIG. 9) and are arranged in the second direction D2. The width of each branch portion 533 is smaller than the width of the trunk portion 531 (extending portions 531A, 531B).

[0053] Among the plurality of individual electrodes 53A, excluding the individual electrodes 53A located at one end and the other end in the first direction D1, each individual electrode 53A straddles two pressure chambers 10 adjacent to each other in the first direction D1 and has a portion overlapping with the two pressure chambers 10 in the third direction D3 (see FIG. 5). The individual electrodes 53A located at one end and the other end in the first direction D1 have a portion overlapping with one pressure chamber 10 in the third direction D3. Further, the individual electrode 53A has a portion overlapping with the driving electrode 51 in the third direction D3. The plurality of individual electrodes 53A are arranged in the first direction D1 and constitute a plurality of individual electrode rows 53R corresponding to each of the driving electrode rows 51R (see FIG. 7). The plurality of individual electrode rows 53R are arranged in the second direction D2. The branch portion 523 connects the plurality of individual electrodes 53A constituting each individual electrode row 53R.

[0054] The high potential portion 57 includes one first portion 57A extending in the second direction D2 and two second portions 57B each extending in the first direction D1. The first portion 57A extends in the second direction D2 at one end of the piezoelectric layer 43 in the first direction D1 (the upper end in FIG. 9). One of the two second portions 57B is connected to one end of the first portion 57A in the second direction D2 (the left end in FIG. 9). The other of the two second portions 57B is connected to the other end of the first portion 57A in the second direction D2 (the right end in FIG. 9). The two second portions 57B each extend from the connection portion with the first portion 57A to the other side in the first direction D1 (the lower side in FIG. 9).

[0055] The two second portions 57B each overlap with the three electrodes 54A (see FIG. 7) of the high potential portion 54 and each extending portion 521B of the high potential electrode 52 in the third direction D3. The two second portions 57B are each electrically connected to the extending portion 521B through a through hole 42X (see FIG. 8) formed in the piezoelectric layer 42 and receive a high potential from the extending portion 521B.

[0056] The two floating electrode portions 66 are respectively disposed between the second portion 57B and the extending portion 531B in the first direction D1 at one end (the left end in FIG. 9) and the other end (the right end in FIG. 9) of the piezoelectric layer 43 in the second direction D2. The two floating electrode portions 66 are each composed of a plurality of electrodes 66A spaced apart from each other in the first direction D1. The electrodes 66A have substantially the same size and shape in a plane orthogonal to the third direction D3 and are arranged at equal intervals in the first direction D1.

[0057] Each electrode 66A of the floating electrode portion 66 is not electrically connected to any other electrode and is not given a potential.

[0058] <Actuator portion> As shown in FIG. 5, a portion of the piezoelectric layer 41 sandwiched between the drive electrode 51 and the individual electrode 52A of the high potential electrode 52 in the third direction D3 is referred to as a first active portion 91. A portion of the piezoelectric layers 42 and 43 sandwiched between the drive electrode 51 and the individual electrode 53A of the low potential electrode 53 in the third direction D3 is referred to as a second active portion 92. The first active portion 91 is mainly polarized upward, and the second active portion 92 is mainly polarized downward. The actuator member 22 has an actuator portion 90 composed of one first active portion 91 and two second active portions 92 for each pressure chamber 10. In each actuator portion 90, the two second active portions 92 are spaced apart from each other in the first direction D1 (the "fourth direction" of the present invention) and sandwich the first active portion 91.

[0059] Here, referring to FIG. 6, the operation of the actuator portion 90 corresponding to the nozzle 15 when discharging ink from a certain nozzle 15 will be described.

[0060] Before the printer 100 starts the recording operation, as shown in Fig. 6(a), a low potential (GND potential) is applied to each drive electrode 51. At this time, due to the potential difference between the drive electrode 51 and the high potential electrode 52, an upward electric field equal to the polarization direction is generated in the first active part 91, and the first active part 91 contracts in the plane direction (the direction along the first direction D1 and the second direction D2). As a result, the portion of the laminate composed of the piezoelectric layers 41 to 43 that overlaps the pressure chamber 10 in the third direction D3 is bent so as to be convex toward the pressure chamber 10 (downward). At this time, the volume of the pressure chamber 10 is smaller than when the laminate is flat.

[0061] When the printer 100 starts the recording operation and ejects ink from a certain nozzle 15, first, as shown in Fig. 6(b), the potential of the drive electrode 51 corresponding to the nozzle 15 is switched from a low potential (GND potential) to a high potential (VDD potential). At this time, the contraction of the first active part 91 is eliminated because the potential difference between the drive electrode 51 and the high potential electrode 52 disappears. On the other hand, when a potential difference is generated between the drive electrode 51 and the low potential electrode 53, a downward electric field equal to the polarization direction is generated in the second active part 92, and the second active part 92 contracts in the plane direction. However, the second active part 92 has a function of suppressing crosstalk (a phenomenon in which pressure fluctuations accompanying the deformation of the actuator part 90 in a certain pressure chamber 10 are transmitted to another pressure chamber 10 adjacent to the pressure chamber 10 in the first direction D1), and hardly contributes to the deformation of the actuator part 90. That is, at this time, the laminate does not bend so that the portion overlapping the pressure chamber 10 in the third direction D3 is convex in the direction away from the pressure chamber 10 (upward), and becomes a flat state. As a result, the volume of the pressure chamber 10 becomes larger than that in Fig. 6(a).

[0062] Thereafter, as shown in FIG. 6(a), the potential of the drive electrode 51 corresponding to the nozzle 15 is switched from a high potential (VDD potential) to a low potential (GND potential). At this time, since the potential difference between the drive electrode 51 and the low potential electrode 53 disappears, the contraction of the second active part 92 is eliminated. On the other hand, since a potential difference is generated between the drive electrode 51 and the high potential electrode 52, an upward electric field equal to the polarization direction is generated in the first active part 91, and the first active part 91 contracts in the plane direction. As a result, the portion of the laminate overlapping the pressure chamber 10 in the third direction D3 bends so as to be convex (downward) toward the pressure chamber 10. At this time, since the volume of the pressure chamber 10 greatly decreases, a large pressure is applied to the ink in the pressure chamber 10, and the ink is ejected from the nozzle 15.

[0063] As described above, according to the head 1 of the present embodiment, as shown in FIG. 3, in the second direction D2, the pressure chamber 10 included in the first individual flow path row 19R1 is farther from the pressure chamber 10 included in the second individual flow path row 19R2 than the nozzle 15 included in the first individual flow path row 19R1, and the pressure chamber 10 included in the second individual flow path row 19R2 is farther from the pressure chamber 10 included in the first individual flow path row 19R1 than the nozzle 15 included in the second individual flow path row 19R2. That is, the region between the pressure chamber 10 included in the first individual flow path row 19R1 and the pressure chamber 10 included in the second individual flow path row 19R2 of the flow path member 21 becomes relatively large in the second direction D2, and in this region, the branch portion 523 is arranged so as to overlap the nozzle 15 included in the first individual flow path row 19R1 and the nozzle 15 included in the second individual flow path row 19R2 in the third direction D3. For this reason, it is possible to form the width (the length in the second direction D2) of the branch portion 523 wide, and it is possible to reduce the calorific value in the branch portion 523. Moreover, since the branch portion 523 does not overlap the pressure chamber 10 in the third direction D3, it is possible to suppress the inhibition of the deformation of the actuator portion 90.

[0064] In addition, by making it possible to form the width of the branch portion 523 wider, the electrical resistance in the branch portion 523 is reduced. As a result, when a plurality of actuator units 90 corresponding to the individual electrodes 52A connected to the same branch portion 523 are driven simultaneously, it becomes difficult for a response difference to occur between these individual electrodes 52A. As a result, it is possible to suppress the occurrence of a difference in the driving timing of the actuator unit 90.

[0065] The branch portion 523 is separated from the pressure chamber 10 in the second direction D2. Thereby, it is possible to effectively suppress the branch portion 523 from overlapping the pressure chamber 10 in the third direction D3 due to manufacturing errors.

[0066] The first communication path 13 of the individual flow path 19 has the first portion 14A and the second portion 14B, and the branch portion 523 overlaps not only the first portion 14A but also the second portion 14B in the third direction D3. Thereby, the width of the branch portion 523 becomes wider.

[0067] The second portion 14B has a flow path width smaller than the flow path width of the first portion 14A. Thereby, it is possible to suppress higher-order frequency components generated when ink is ejected from the nozzle 15 with a simple configuration. When ink is ejected from the nozzle 15, a pressure wave is generated in the first communication path 13. This pressure wave can be represented by a plurality of frequency components when subjected to FFT analysis. Among the plurality of frequency components, higher-order frequency components from the second harmonic and above can be significantly reduced by restricting the flow rate by the throttle portion 14C. By reducing the higher-order frequency components, the influence of the higher-order frequency components on the ink ejection from the nozzle 15 can be suppressed. As a result, a predetermined amount of ink droplets can be stably ejected from the nozzle 15. Note that the first communication path 13 may not have the throttle portion 14C.

[0068] The actuator unit 90 has a first active portion 91 and two second active portions 92 (see FIG. 6). In this case, when the pressure fluctuation accompanying the deformation of the first active portion 91 is transmitted to the adjacent pressure chamber 10, it is canceled by the deformation of the second active portion 92, so that crosstalk can be effectively suppressed.

[0069] The branch portion 523 does not overlap with the drive electrode 51 in the third direction D3. Thereby, it becomes possible to suppress dielectric breakdown at the portion where the branch portion 523 and the drive electrode 51 overlap in the actuator member 22.

[0070] <Second Embodiment> Subsequently, referring to FIG. 10, the head 201 according to the second embodiment of the present invention will be described. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. The head 201 in the present embodiment is the same except that the shape of the branch portion 523 of the high potential electrode 52 is different from that of the branch portion 523 in the first embodiment.

[0071] The branch portion 523 has a plurality of protruding regions 550 that protrude in the second direction D2 from the end of the branch portion 523 in the second direction D2. These protruding regions 550 overlap with the region between the two pressure chambers 10 adjacent in the first direction D1 in the third direction D3. Thereby, since the width of the branch portion 523 can be widened at the portion where the protruding region 550 is provided, it becomes possible to make the electrical resistance in the branch portion 523 smaller, and heat generation in the branch portion 523 can be suppressed.

[0072] <Third Embodiment> Subsequently, referring to FIG. 11, the head 301 according to the third embodiment of the present invention will be described. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. The head 301 in the present embodiment is the same except that the shape of the first communication passage 313 is different from that of the first communication passage 13 in the first embodiment.

[0073] As shown in FIG. 11, the first connection passage 313 extends linearly from the pressure chamber 10 toward the nozzle 15. Also in this embodiment, the branch portion 523 overlaps with the nozzle 15 and the first connection passage 313 in the third direction D3. Thereby, compared with the first connection passage 13 including the above-described first portion 14A and second portion 14B, the pressure loss in the first connection passage 313 can be reduced. Note that the first connection passage 313 includes those that extend substantially linearly from the pressure chamber 10 toward the nozzle 15 by a plurality of holes formed in a plurality of plates constituting the flow path member 21 and having central axes along the vertical direction communicating in a stepped manner.

[0074] <Fourth Embodiment> Next, with reference to FIG. 12, a head according to a fourth embodiment of the present invention will be described. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. The head in this embodiment is the same except that the shape of the branch portion 523 of the high-potential electrode 52 is different from that of the branch portion 523 in the first embodiment.

[0075] In the branch portion 523, the length in the second direction D2 becomes shorter as it moves away from the trunk portion 521 in the first direction D1. If the width of the branch portion 523 is large, the actuator member 22 is likely to warp due to thermal contraction during electrode firing. Here, the amount of flowing charge is smaller in the portion of the branch portion 523 farther from the trunk portion 521, and the width can be reduced. In this configuration, by reducing the width of the branch portion 523 in the portion where the amount of charge is small, it is possible to effectively suppress the warping of the actuator member 22 while suppressing the heat generation amount of the branch portion 523.

[0076] <Fifth Embodiment> Next, with reference to FIG. 13, a head according to a fifth embodiment of the present invention will be described. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. The head in this embodiment is the same except that the shape of the branch portion 523 of the high-potential electrode 52 is different from that of the branch portion 523 in the first embodiment.

[0077] Among the seven branch portions 523 in the present embodiment, the length of the branch portion 523 in the second direction D2 becomes shorter as it goes outward along the second direction D2 from the branch portion 523 located at the center in the second direction D2. In other words, among the seven branch portions 523, the closer the branch portion 523 is to the extending portion 521B provided with the contact point with the power supply portion in the second direction, the shorter the length in the second direction.

[0078] For example, when all the actuator portions 90 are driven simultaneously, charges flow from the seven branch portions 523 to the power supply portion through the extending portion 521A. At this time, charges flow more easily to the power supply portion in the branch portion 523 closer to the power supply portion. For this reason, the central branch portion 523 far from the power supply portion in the second direction D2 generates more heat than the branch portion 523 closer to the power supply portion. In the present embodiment, by increasing the width of the central branch portion 523, the electrical resistance in the branch portion 523 is reduced to suppress heat generation. On the other hand, since the branch portion 523 close to the power supply portion in the second direction D2 generates less heat, it is not necessary to increase the width of the branch portion 523. In other words, by making the width of the central branch portion 523 larger than that of the branch portion 523 close to the power supply portion, charges flow more easily from the central branch portion 523 to the extending portion 521A than from the branch portion 523 close to the power supply portion, and heat generation in the central branch portion 523 can be suppressed. Therefore, it is possible to suppress a local (the central branch portion 523) increase in the amount of heat generation among the seven branch portions 523.

[0079] Also, in this configuration, by reducing the width of the branch portion 523 close to the power supply portion in the second direction D2, it becomes possible to effectively suppress the warping of the actuator member 22 as described above.

[0080] As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to the above-described embodiments, and various modifications are possible as long as they are within the scope described in the claims.

[0081] The branch portion 523 in the above-described first, second, fourth, and fifth embodiments overlaps with the second portion 14B of the first communication path 13 in the third direction D3, but it may overlap with the first portion 14A in the third direction D3 and not overlap with the second portion 14B.

[0082] If the branch portion 523 does not overlap with the pressure chamber 12P in the third direction D3, it may not be separated from the pressure chamber 12P in the second direction D2.

[0083] The first potential is not limited to being a high potential and the second potential being a low potential, and vice versa (i.e., the first potential is a low potential and the second potential is a high potential) may also be possible. In this case, the high potential electrode 52 may be located in the lowermost layer and the low potential electrode 53 may be located in the intermediate layer.

[0084] The number of piezoelectric layers constituting the actuator member is three in the above-described embodiment, but may be two or four or more. For example, in the above-described embodiment (see FIG. 4), a diaphragm made of stainless steel or the like may be provided instead of the piezoelectric layer 43. Alternatively, in the above-described embodiment (see FIG. 4), another piezoelectric layer may be disposed between the piezoelectric layer 43 of the actuator member 22 and the plate 31 of the flow path member 21.

[0085] The type of the liquid ejection head of the present invention is not limited to the line type, and may be the serial type.

[0086] The target for ejecting droplets is not limited to paper. For example, the target for ejecting droplets may be cloth, a substrate, or plastic.

[0087] The droplets ejected from the nozzle are not limited to ink droplets. For example, the droplets may be droplets of a treatment liquid that aggregates or precipitates components in the ink.

[0088] The present invention is not limited to printers, and is also applicable to facsimiles, copiers, and multifunction devices. Further, the present invention is also applicable to liquid ejection devices used for purposes other than image recording. For example, the present invention is applicable to a liquid ejection device that ejects a conductive liquid onto a substrate to form a conductive pattern.

Explanation of Reference Numerals

[0089] 1,201,301 Head 10 Pressure chamber 13,313 First connection path 14A First part 14B Second part 15 Nozzle 19 Individual flow path 19R Individual flow path row 19R1 First individual flow path row 19R2 Second individual flow path row 21 Flow path member 21A Surface 22 Actuator member 40 Piezoelectric body 41 - 43 Piezoelectric layer 51 Driving electrode 52 High - potential electrode 53 Low - potential electrode 52A Individual electrode 70 Electrode body 71 Electrode layer (first electrode layer) 72 Electrode layer (second electrode layer) 73 Electrode layer (third electrode layer) 90 Actuator part 91 First active part 92 Second active part 521 Trunk part 523 Branch part 550 Protruding region D1 First direction (fourth direction) D2 Second direction D3 Third direction

Claims

1. A flow path member in which a plurality of individual flow paths each including a nozzle and a pressure chamber communicating with the nozzle are formed, the flow path member having a plurality of individual flow path rows each having the plurality of individual flow paths arranged in a first direction and arranged in a second direction orthogonal to the first direction, and an actuator member disposed on a surface of the flow path member and having a plurality of actuator portions overlapping in a third direction orthogonal to the surface of each of the pressure chambers of the plurality of individual flow paths, the actuator member including a plurality of individual electrodes constituting the plurality of actuator portions, a branch portion extending along the first direction and connecting the plurality of individual electrodes, and a trunk portion connected to the branch portion and provided with a contact point with a power supply portion, the nozzle included in the first individual flow path row among the plurality of individual flow path rows and the nozzle included in the second individual flow path row adjacent to the first individual flow path row among the plurality of individual flow path rows are arranged in the second direction between the pressure chamber included in the first individual flow path row and the pressure chamber included in the second individual flow path row, the branch portion is arranged between the pressure chamber included in the first individual flow path row and the pressure chamber included in the second individual flow path row in the second direction, and overlaps with the nozzle included in the first individual flow path row and the nozzle included in the second individual flow path row in the third direction, a liquid discharge head characterized by this.

2. The liquid discharge head according to claim 1, wherein the branch portion is separated from the pressure chamber in the second direction.

3. The liquid discharge head according to claim 1, wherein the branch portion is a protruding region protruding in the second direction and has a protruding region overlapping in the third direction with a region between two of the pressure chambers adjacent to each other in the first direction belonging to one of the plurality of individual flow path rows.

4. The individual flow path further includes a communication path having one end communicating with the nozzle and the other end communicating with the pressure chamber, the communication path includes a first portion constituting the one end and extending in the third direction, and a second portion constituting the other end and extending in a direction orthogonal to the third direction and intersecting the first direction, The liquid discharge head according to claim 1, wherein the branch portion overlaps not only the first portion but also the second portion in the third direction.

5. The liquid ejection head according to claim 4, wherein the second portion has a flow path width smaller than the flow path width of the first portion.

6. The individual flow path further includes a communication path having one end communicating with the nozzle and the other end communicating with the pressure chamber, The liquid ejection head according to claim 1, wherein the communication path extends linearly from the pressure chamber toward the nozzle.

7. The liquid ejection head according to claim 1, wherein the length of the branch portion in the second direction becomes shorter as the branch portion is farther from the trunk portion in the first direction.

8. The actuator member includes a plurality of the branch portions connected to the trunk portion, The liquid ejection head according to claim 1, wherein the lengths of the plurality of branch portions in the second direction become shorter as the branch portions are closer to the power supply portion in the second direction.

9. The actuator member, A piezoelectric body including a plurality of piezoelectric layers laminated in the third direction, An electrode body including a first electrode layer, a second electrode layer separated from the first electrode layer in the third direction, and a third electrode layer separated from the first electrode layer in the third direction, The first electrode layer is a plurality of first electrodes to which a first potential and a second potential different from the first potential are selectively applied, and includes a plurality of first electrodes overlapping with the pressure chambers of the plurality of individual flow paths in the third direction, The second electrode layer includes a second electrode held at the first potential, The third electrode layer includes a third electrode held at the second potential, The piezoelectric body has a first active portion sandwiched between the first electrode and the second electrode in the third direction, and two second active portions sandwiched between the first electrode and the third electrode in the third direction. The two second active portions are separated from each other in a fourth direction orthogonal to the second direction and the third direction, and sandwich the first active portion. The liquid ejection head according to claim 1, wherein at least one of the second electrode and the third electrode has the plurality of individual electrodes, the branch portion, and the trunk portion.

10. The liquid ejection head according to claim 9, wherein the branch portion does not overlap with the first electrode in the third direction.

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