JP6950766B2 - Liquid discharge device - Google Patents

Description

The present invention relates to a liquid discharge device.

Patent Document 1 discloses an inkjet head as a liquid ejection device that ejects ink onto a recording medium to record an image or the like. The inkjet head of Patent Document 1 includes a nozzle plate in which a plurality of nozzles are formed, a flow path forming substrate in which a plurality of pressure chambers communicating with the plurality of nozzles are formed, and a plurality of pressure chambers in the flow path forming substrate. It has a plurality of piezoelectric elements provided corresponding to each of the above, and a reservoir forming substrate bonded to the flow path forming substrate so as to cover the plurality of piezoelectric elements. The plurality of nozzles are arranged in two rows, and correspondingly, the plurality of pressure chambers and the plurality of piezoelectric elements are also arranged in two rows.

Wiring is connected to each of the individual electrodes of the plurality of piezoelectric elements. The plurality of wires extend from the corresponding piezoelectric elements in a direction orthogonal to the arrangement direction of the piezoelectric elements, and are drawn out to a region outside the reservoir forming substrate. Further, the plurality of wirings are electrically connected to a driving device (driving circuit) arranged on the reservoir forming substrate by wire bonding. The drive device outputs a drive signal to each piezoelectric element via wiring.

The reservoir forming substrate has a total of three portions, two outer wall portions located outside the two rows of piezoelectric element rows in a direction orthogonal to the arrangement direction, and an inner side wall portion located between the two rows of piezoelectric element rows. Has a wall. The above three wall portions are respectively joined to the flow path forming substrate. The outer wall portion is joined on the wiring drawn from the individual electrodes of each piezoelectric element. The width of the two outer wall portions of the reservoir forming substrate is smaller than that of the inner side wall portion.

Japanese Unexamined Patent Publication No. 2003-127365

By the way, when a drive signal is output to each piezoelectric element, heat is generated in the drive device. Since a part of this heat is transferred to the flow path forming substrate via a plurality of wirings, the temperature of the piezoelectric element and the temperature of the liquid in the pressure chamber rise. At this time, if the difference in the amount of heat transfer between the plurality of pressure chambers or the plurality of piezoelectric elements is large, it becomes a factor that a large difference in discharge characteristics occurs between the plurality of nozzles. Therefore, in order to suppress the above-mentioned variation in discharge characteristics, it is effective to dissipate as much heat as possible from the drive device through the wiring before it is transferred to the piezoelectric element or the liquid in the pressure chamber.

In this regard, in Patent Document 1, wiring is drawn out from each of the plurality of piezoelectric elements arranged in two rows to the outer region of the reservoir forming substrate. That is, the wiring is arranged in the joint region between the outer wall portion of the reservoir forming substrate and the flow path forming substrate. Therefore, it is considered that a part of the heat transmitted from the drive device through the wiring is dissipated from the outer wall portion of the reservoir forming substrate. However, in Patent Document 1, since the width of the outer wall portion of the reservoir forming substrate (joint area with the flow path forming substrate) is small, the heat dissipation effect through the reservoir forming substrate cannot be expected so much.

An object of the present invention is to promote heat transfer from the drive device to the wiring, and to suppress heat transfer to the liquid in the pressure chamber and the piezoelectric element.

The liquid discharge device of the first invention includes a flow path structure having a plurality of nozzles arranged in the first direction and a plurality of pressure chambers arranged in the first direction corresponding to the plurality of nozzles. In the flow path structure, a plurality of piezoelectric elements arranged in the first direction corresponding to the plurality of pressure chambers are arranged side by side in a second direction orthogonal to the first direction, and the flow is described. A cover member having a plurality of wall portions joined to the road structure and covering the plurality of piezoelectric elements, and the plurality of piezoelectric elements being drawn out from the plurality of piezoelectric elements on one side in the second direction, respectively, from the piezoelectric element. A plurality of lead wires extending to the outside of the cover member through a joint region between the wall portion located on one side and the flow path structure, and a drive device electrically connected to the plurality of lead wires. The plurality of wall portions are joined to the flow path structure to sandwich the piezoelectric element in the second direction, and the one side of the plurality of wall portions in the second direction. The wall portion located at the end is characterized in that the joint area with the flow path structure is larger than that of the wall portion located on the other side of the second direction. be.

In the present invention, since the lead-out wiring drawn from the piezoelectric element passes through the joint region between the flow path structure and the wall portion of the cover member, the heat transferred from the drive device to the lead-out wiring in this joint region is generated. A part can be released to the cover member. Further, among the plurality of wall portions, many lead wires pass through the joint region of the wall portion located at one end in the second direction. In the present invention, the wall portion located at the one end has a larger joint area than the other wall portion. That is, since the wall portion having a large joining area is joined to the region through which many lead wirings pass, the heat transferred to the lead wiring can be effectively released to the cover member.

In the liquid discharge device of the second invention, in the first invention, the wall portion located at the one end of the plurality of wall portions in the second direction is the second wall portion of the wall portion. It is characterized in that the width in the second direction is larger than that of the wall portion located on the other side in the two directions.

In the present invention, the width of the wall portion located at the one end on the one side in the second direction is increased in the second direction, so that a configuration in which the joint area with the flow path structure is large is realized.

In the liquid discharge device of the third invention, in the first or second invention, the plurality of piezoelectric elements form a plurality of piezoelectric element trains arranged in the second direction, and the plurality of wall portions form the plurality of piezoelectric element trains. An outer wall portion that is joined to the flow path structure on one side of the second direction with respect to the plurality of piezoelectric element rows, and an inner side that is joined to the flow path structure between the plurality of piezoelectric element rows. It has a wall portion, and the joint area of the outer wall portion is larger than the joint area of the inner side wall portion.

In the joint region of the outer side wall portion, the number of wires passing through is larger than that in the joint region of the inner side wall portion located between the plurality of piezoelectric element rows. In the present invention, since the joint area of the outer wall portion to be joined to the region through which many wirings pass is large, the heat transmitted through the lead wiring can be effectively released to the cover member.

Further, since the cover member has a structure having an inner side wall portion in addition to the two outer wall portions, it is possible to prevent the central portion of the cover member from bending when the cover member is joined to the flow path structure. Further, when the cover member is joined to the flow path structure with an adhesive while being heated, the cover member may warp and a force in the direction of peeling from the flow path substrate may act on the outer wall portion. Even in this case, since the joint area of the outer wall portion is larger than that of the inner side wall portion, peeling of the outer wall portion can be prevented.

In the liquid discharge device of the fourth invention, in the third invention, the cover member has a plurality of inner side wall portions arranged in the second direction, and the plurality of inner side wall portions are in the second direction. The one located on one side of the above is characterized in that the joint area with the flow path structure is larger.

In the joint region of the inner side wall portion located on the wiring lead-out side, the number of wires passing through is large. Therefore, in the present invention, the plurality of inner side wall portions located on the wiring lead-out side have a larger joint area with the flow path structure. That is, as the number of the drawn-out wirings passing through is large, the wall portion having a large joining area is joined, so that the heat transferred to the lead-out wiring can be effectively released to the cover member.

In the liquid discharge device of the fifth invention, in the third or fourth invention, a convex portion extending in the first direction is formed in a region of the flow path structure to which the inner side wall portion is joined. It is characterized by being.

In the present invention, a convex portion extending in the first direction is formed in the region where the inner side wall portion of the flow path structure is joined. As a result, when the inner side wall portion is bonded to the flow path structure with an adhesive, the excess adhesive is restricted from moving in the second direction between the two piezoelectric element trains. Therefore, it is possible to prevent the adhesive from flowing from one piezoelectric element row side to the other piezoelectric element row side beyond the inner side wall portion.

The liquid discharge device of the sixth invention is characterized in that, in the fifth invention, a plurality of the convex portions are arranged at intervals in the second direction.

In the present invention, since a plurality of convex portions are arranged side by side at intervals in the second direction in the region where the inner side wall portions of the flow path structure are joined, the flow of the adhesive in the second direction can be prevented. The effect of regulation will increase. Further, since the surface of the joint region has an uneven shape, the adhesive force between the inner side wall portion and the flow path structure is increased.

In the fifth or sixth invention of the seventh invention, the convex portion is formed of the same conductive material as the drawer wiring, and the height of the convex portion is the height of the drawer wiring. It is characterized by being equal to the thickness.

In the present invention, since the convex portion is formed of the same conductive material as the drawer wiring, it is possible to form the convex portion and the drawer wiring in the same process. Further, since the height of the convex portion and the thickness of the lead wiring are equal to each other, it is possible to make the height of the joint surface uniform between the joint region with the inner side wall portion and the joint region with the outer wall portion of the flow path structure. can.

In the first or second invention, the liquid discharge device of the eighth invention is the first piezoelectric element group and the second piezoelectric element, each of which is composed of a plurality of the piezoelectric elements and is arranged in the second direction. From the piezoelectric element having a group and forming the first piezoelectric element group, the lead wire extends to the one side in the second direction, and from the piezoelectric element forming the second piezoelectric element group, the piezoelectric element The lead wire extends to the other side in the second direction, and the plurality of wall portions have the one side and the other side in the second direction with respect to the first piezoelectric element group and the second piezoelectric element group. The outer wall portion has two outer wall portions that are joined to the flow path structure and a central wall portion that is joined to the flow path structure between the two piezoelectric element groups. The joint area is larger than the joint area of the central wall portion.

In the present invention, since the cover member has a structure having a central wall portion in addition to the two outer wall portions, it is possible to prevent the central portion of the cover member from bending when the cover member is joined to the flow path structure. can. Further, when the cover member is joined to the flow path structure with an adhesive while being heated, the cover member may warp and a force in the direction of peeling from the flow path substrate may act on the outer wall portion. Even in this case, since the joint area of the outer wall portion is larger than that of the central wall portion, it is possible to prevent the outer wall portion from peeling off.

In the liquid discharge device of the ninth invention, in the eighth invention, a convex portion extending in the first direction is formed in a region of the flow path structure to which the central wall portion is joined. It is characterized by.

In the present invention, a convex portion extending in the first direction is formed in a region of the flow path structure to which the central wall portion is joined. Thereby, when the central wall portion is bonded to the flow path structure with an adhesive, it is possible to restrict the excess adhesive from moving in the second direction between the two piezoelectric element groups. Therefore, it is possible to prevent the adhesive from flowing from one piezoelectric element group side to the other piezoelectric element group side beyond the central wall portion.

The liquid discharge device of the tenth invention is characterized in that, in the ninth invention, a plurality of the convex portions are arranged at intervals in the second direction.

In the present invention, since a plurality of convex portions are arranged side by side at intervals in the second direction in the region where the central wall portion of the flow path structure is joined, the flow of the adhesive in the second direction can be prevented. The effect of regulation will increase. Further, since the surface of the joint region has an uneven shape, the adhesive force between the central wall portion and the flow path structure is enhanced.

In the tenth aspect of the invention, the liquid discharge device of the eleventh invention has the convex portion located at the central portion of the joint region of the central wall portion in the second direction among the plurality of convex portions. It is characterized by having a length equal to or longer than the total length in the first direction of the piezoelectric element group adjacent to the convex portion.

No lead wiring is arranged in the joint region of the flow path structure with the central wall portion. Therefore, the convex portion can be formed in a shape that extends continuously in the transport direction. On top of that, in the present invention, the convex portion located at the central portion of the bonding region has a length equal to or longer than the total length of the piezoelectric element group. As a result, with this configuration, the flow of excess adhesive between the two piezoelectric element group sides arranged so as to sandwich the central wall portion is surely suppressed.

In the liquid discharge device of the twelfth invention, in any one of the ninth to eleventh inventions, the convex portion is formed of the same conductive material as the lead wiring, and the height of the convex portion is the said. It is characterized in that it is equal to the thickness of the lead wire.

In the present invention, since the convex portion is formed of the same conductive material as the drawer wiring, it is possible to form the convex portion and the drawer wiring in the same process. Further, since the height of the convex portion and the thickness of the lead wiring are equal, the height of the joint surface of the flow path structure can be made uniform between the joint region with the central wall portion and the joint region with the outer wall portion. can.

In the liquid discharge device of the thirteenth invention, in any one of the first to twelfth inventions, a first layer is laminated in contact with the drawer wiring on the flow path structure side of the plurality of leader wirings. A second layer is laminated in contact with the drawer wiring on the cover member side of the plurality of drawer wirings, and the second layer has a higher thermal conductivity than the first layer. It is characterized in that it is made of a material.

In the present invention, with respect to the lead-out wiring, the first layer arranged on the cover member side is formed of a material having a higher thermal conductivity than the second layer arranged on the flow path structure side. Therefore, the heat transmitted from the drive device through the lead-out wiring can be easily released to the cover member.

In the liquid discharge device of the fourteenth invention, in any one of the first to thirteenth inventions, at least a part of the plurality of drawer wirings is the wall portion located at the one-sided end in the second direction. It is characterized in that it crosses the joint region between the flow path structure and the flow path structure in a direction intersecting the second direction.

In the present invention, since at least a part of the lead-out wiring extends diagonally across the joint region, the contact length of the lead-out wiring with the wall portion becomes long. As a result, the heat transmitted from the drive device through the lead-out wiring can be easily released to the cover member.

It is a schematic plan view of the printer which concerns on this embodiment. It is a top view of the inkjet head. It is an enlarged view of the part A of FIG. FIG. 3 is a sectional view taken along line IV-IV of FIG. It is a partially enlarged plan view of the inkjet head of a modified form. It is a top view of the inkjet head of another modified form. It is a top view of the inkjet head of another modified form. FIG. 7 is a cross-sectional view taken along the line VIII-VIII of FIG.

Next, an embodiment of the present invention will be described. FIG. 1 is a schematic plan view of a printer according to the present embodiment. The front, back, left, and right directions shown in FIG. 1 are defined as "front", "rear", "left", and "right" of the printer. Further, the front side of the paper surface in FIG. 1 is defined as "upper", and the other side of the paper surface is defined as "lower". In the following, each direction word of front, back, left, right, up and down will be described as appropriate.

(Outline configuration of printer)
As shown in FIG. 1, the inkjet printer 1 includes a platen 2, a carriage 3, an inkjet head 4, a cartridge holder 5, a transport mechanism 6, a control device 7, and the like.

The recording paper 100, which is the recording medium, is placed on the upper surface of the platen 2. The recording paper 100 faces the inkjet head 4 described later at intervals suitable for image formation. The carriage 3 is supported by two guide rails 11 and 12, and can reciprocate in the left-right direction (hereinafter, also referred to as a scanning direction). An endless belt 13 is connected to the carriage 3, and when the carriage drive motor 14 is driven, the carriage 3 moves together with the endless belt 13 in the scanning direction.

The inkjet head 4 (the liquid ejection device of the present invention) is mounted on the carriage 3. The inkjet head 4 is provided with a plurality of nozzles 24 (see FIGS. 2 to 4) on the lower surface thereof (the surface on the opposite side of the paper surface of FIG. 1).

Ink cartridges 15 of four colors (black, yellow, cyan, magenta) are detachably mounted on the cartridge holder 5. The ink cartridge 15 is connected to the inkjet head 4 by a tube (not shown). The ink of each ink cartridge 15 is supplied to the inkjet head 4 via a tube. The inkjet head 4 moves in the scanning direction together with the carriage 3 and ejects ink from the nozzle 24 on the lower surface thereof toward the recording paper 100 mounted on the platen 2. The detailed configuration of the inkjet head 4 will be described later.

The transport mechanism 6 has two transport rollers 16 and 17 arranged so as to sandwich the platen 2 in the front-rear direction. The two transfer rollers 16 and 17 are driven in synchronization with each other by a transfer motor (not shown). The transport mechanism 6 transports the recording paper 100 mounted on the platen 2 forward (hereinafter, also referred to as a transport direction) by the two transport rollers 16 and 17.

The control device 7 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an ASIC (Application Specific Integrated Circuit) including various control circuits, and the like. The control device 7 causes the ASIC to execute various processes such as printing on the recording paper 100 by executing the program stored in the ROM on the CPU. For example, in the printing process, the control device 7 controls the inkjet head 4, the carriage drive motor 14, the transport motor of the transport mechanism 6, and the like based on a print command input from an external device such as a PC to record paper. Have 100 print an image or the like. More specifically, the ink ejection operation of ejecting ink while moving the inkjet head 4 together with the carriage 3 in the scanning direction and the conveying operation of conveying a predetermined amount of the recording paper 100 in the conveying direction by the conveying rollers 16 and 17 are performed. Let them do it alternately.

(Details of inkjet head)
Next, the configuration of the inkjet head 4 will be described in detail. FIG. 2 is a plan view of the inkjet head 4 shown in FIG. FIG. 3 is an enlarged view of part A of FIG. FIG. 4 is a sectional view taken along line IV-IV of FIG. As shown in FIGS. 2 to 4, the inkjet head 4 includes a nozzle plate 20, a flow path substrate 21, a piezoelectric actuator 22, a cover member 23, and the like. In FIGS. 2 and 3, for simplification of the drawings, the COF 51 and the cover member 23 joined to the upper surface of the flow path substrate 21 are schematically shown by an alternate long and short dash line.

(Nozzle plate)
The nozzle plate 20 is, for example, a plate made of silicon or the like. A plurality of nozzles 24 arranged in the transport direction (first direction of the present invention) are formed on the nozzle plate 20.

More specifically, as shown in FIG. 2, the nozzle plate 20 is formed with four nozzle groups 27 arranged in the scanning direction (second direction of the present invention). The four nozzle groups 27 eject inks that are different from each other. In the following description, among the components of the inkjet head 4, those corresponding to black (K), yellow (Y), cyan (C), and magenta (M) inks are shown. After the code, one of the symbols "k" for black, "y" for yellow, "c" for cyan, and "m" for magenta is appropriately used to indicate which ink is supported. Attach. For example, the nozzle group 27k refers to the nozzle group 27 that ejects black ink. One nozzle group 27 is composed of two left and right nozzle rows 28. In each nozzle row 28, a plurality of nozzles 24 are arranged at an arrangement pitch P. Further, the position of the nozzle 24 is shifted by P / 2 in the transport direction between the two nozzle rows 28. That is, the plurality of nozzles 24 constituting one nozzle group 27 are arranged in two rows in a staggered pattern.

(Flower board)
The flow path substrate 21 is a silicon single crystal substrate. A plurality of pressure chambers 26 communicating with the plurality of nozzles 24 are formed in the flow path substrate 21, and all of them penetrate the flow path substrate 21. Each pressure chamber 26 has a rectangular planar shape that is long in the scanning direction. The plurality of pressure chambers 26 are arranged in the transport direction according to the arrangement of the plurality of nozzles 24 described above, and form two pressure chamber rows for one color of ink, for a total of eight pressure chamber rows. The lower surface of the flow path substrate 21 is covered with the nozzle plate 20, and the outer end of each pressure chamber 26 overlaps with the nozzle 24. Specifically, as shown in FIG. 3, in the pressure chamber row on the right side, the right end portion of each pressure chamber 26 and the nozzle 24 overlap, and in the pressure chamber row on the left side, the left end portion of each pressure chamber 26 and the nozzle 24 overlap. It overlaps with the nozzle 24. The nozzle plate 20 and the flow path substrate 21 described above correspond to the "flow path structure" of the present invention.

The upper surface of the flow path substrate 21 is covered with the vibrating membrane 30. The vibrating film 30 is a film formed by oxidizing or nitriding the surface of a silicon substrate. The vibrating film 30 may be a silicon oxide film or a silicon nitride film laminated by a sputtering method, a CVD method, or the like. An ink supply hole 30a is formed in a portion of the vibrating film 30 that covers the inner end of each pressure chamber 26 (the end opposite to the nozzle 24).

Ink is supplied from the reservoir 60 in the cover member 23, which will be described later, to each pressure chamber 26 through the ink supply hole 30a. Then, when the ejection energy is applied to the ink in the pressure chamber 26 by the piezoelectric actuator 22 described below, the ink droplets are ejected from the nozzle 24 communicating with the pressure chamber 26.

(Piezoelectric actuator)
The piezoelectric actuator 22 includes a vibrating film 30 and a plurality of piezoelectric elements 31, and imparts ejection energy for ejecting from the nozzle 24 to the inks in the plurality of pressure chambers 26, respectively. As shown in FIGS. 2 to 4, the plurality of piezoelectric elements 31 are arranged on the upper surface of the vibrating membrane 30 corresponding to the pressure chambers 26, respectively.

The configuration of the piezoelectric element 31 will be described. The piezoelectric element 31 includes a common electrode 32, a piezoelectric body 33, and an individual electrode 34, which are laminated in this order. As shown in FIG. 4, the common electrode 32 includes a region of the vibrating membrane 30 facing a plurality of pressure chambers 26, and is formed on substantially the entire surface of the vibrating membrane 30. On the common electrode 32, eight strip-shaped piezoelectric bodies 33 are formed corresponding to each of the eight pressure chamber rows. As shown in FIG. 2, each piezoelectric body 33 has a long planar shape in the transport direction, and is arranged so as to straddle a plurality of pressure chambers 26 forming a corresponding pressure chamber row in the transport direction. The piezoelectric body 33 is formed of, for example, a piezoelectric material containing lead zirconate titanate (PZT), which is a mixed crystal of lead titanate and lead zirconate, as a main component. Alternatively, the piezoelectric body 33 may be formed of a lead-free piezoelectric material that does not contain lead.

On the upper surface of each piezoelectric body 33, a plurality of individual electrodes 34 are formed so as to individually face the plurality of pressure chambers 26. Each individual electrode 34 has a rectangular planar shape that is one size smaller than the pressure chamber 26, and is arranged so as to overlap the central portion of the corresponding pressure chamber 26. The individual electrode 34 is made of, for example, iridium (Ir).

In the above configuration, for one pressure chamber 26, one piezoelectric element 31 is configured by each portion of the common electrode 32, the piezoelectric body 33, and the individual electrode 34 facing the pressure chamber 26. In other words, the common electrode 32 and the piezoelectric body 33 are shared among the plurality of piezoelectric elements 31. The portion of the piezoelectric body 33 sandwiched between the common electrode 32 and the individual electrode 34 is hereinafter referred to as an active portion 36.

Further, the plurality of piezoelectric elements 31 are arranged in the transport direction according to the arrangement of the plurality of pressure chambers 26. As a result, the plurality of piezoelectric elements 31 form two piezoelectric element rows 37 for one color of ink, for a total of eight piezoelectric element rows 37, according to the arrangement of the nozzle 24 and the pressure chamber 26. A group of piezoelectric elements 31 composed of two piezoelectric element rows 37 corresponding to one color of ink is referred to as a piezoelectric element group 38. As shown in FIG. 2, four piezoelectric element groups 38 (38k, 38y, 38c, 38m) corresponding to the four color inks are arranged side by side in the scanning direction.

Here, in the piezoelectric element 31, when an electric field acts between the electrodes 32 and 34, the active portion 36 is deformed in the plane direction. In combination with the diaphragm 30, the piezoelectric element 31 undergoes unimorph deformation in a direction orthogonal to the plane. At this time, the volume of the corresponding pressure chamber 26 changes. In this way, for one pressure chamber 26, one individual actuator is configured from the portion of the diaphragm 30 facing the pressure chamber 26 and one piezoelectric element 31. It can be said that the piezoelectric actuator 22 includes as many individual actuators as the number of pressure chambers 26.

Further, as shown in FIG. 4, the piezoelectric actuator 22 has a protective film 40, an insulating film 41, a lead wiring 42, and a wiring protective film 43. In FIGS. 2 and 3, the protective film 40, the insulating film 41, and the wiring protective film 43 are not shown in order to make the drawings easier to see.

As shown in FIG. 4, the protective film 40 is arranged so as to cover the eight piezoelectric bodies 33. The protective film 40 prevents moisture from reaching the piezoelectric body 33 from the air. The protective film 40 is made _{of a material having low water permeability, for example, an oxide such as alumina (Al 2} O ₃ ), silicon oxide (SiOx), tantalum oxide (TaOx), or a nitride of silicon nitride (SiN). It is preferably formed.

An insulating film 41 is formed on the protective film 40. The material of the insulating film 41 is not particularly limited, but is formed of, for example, silicon dioxide (SiO ₂ ). The insulating film 41 is provided in order to improve the insulating property between the lead wiring 42 described below connected to the individual electrode 34 and the common electrode 32.

On the insulating film 41, a plurality of drawing wires 42 drawn from individual electrodes 34 of the plurality of piezoelectric elements 31 are arranged in contact with the insulating film 41. The lead-out wiring 42 is made of a material having a low electrical resistivity such as aluminum (Al) or gold (Au). Further, the plurality of lead wiring 42s connected to the piezoelectric element 31 are extended to the right and left separately. Specifically, as shown in FIGS. 2 and 3, the lead wiring 42 extends to the right from the piezoelectric elements 31 constituting the two piezoelectric element groups 38k and 38y on the right side of the four piezoelectric element groups 38. The lead wiring 42 extends to the left from the piezoelectric elements 31 constituting the two piezoelectric element groups 38c and 38m on the left side.

Each lead-out wiring 42 passes through a joint region with the wall portion 62 of the cover member 23, which will be described later, and extends to the left end portion and the right end portion of the flow path substrate 21. Further, a drive contact portion 46 is provided at the end portion of each drawer wiring 42 on the drawer side. A ground contact portion 47 is also arranged at the left end portion and the right end portion of the flow path substrate 21. At the left and right ends of the flow path substrate 21, the drive contact portions 46 are arranged in a row, and two ground contact portions 47 are arranged on both sides of the arrangement of the drive contact portions 46. Although not shown, the ground contact portion 47 is connected to the common electrode 32 via a through hole that penetrates the protective film 40 and the insulating film 41 directly below.

As shown in FIG. 2, the ink supply holes 30a of the vibrating film 30 are all surrounded by an annular conductor. On the downstream side of the lead-out wiring 42 in the pull-out direction, the conductor (conductive portion 44) is connected to the drive contact portion 46 by the draw-out wiring 42. On the other hand, on the upstream side, a part of the conductor (conductive portion 44) is connected to the lead-out wiring 42 as in the downstream side. However, the residue of the conductor (conductive portion 45) is independent without being connected to the lead-out wiring 42. By surrounding each ink supply hole 30a with the annular conductive portions 44 and 45, the watertightness with respect to the ink supply hole 30a when the cover member 23 described later is joined to the flow path substrate 21 is enhanced.

As shown in FIG. 4, the wiring protection film 43 is laminated in contact with the lead wiring 42, and covers the plurality of lead wiring 42 from above. The wiring protection film 43 enhances the insulation between the plurality of lead wirings 42. The wiring protection film 43 does not cover the end portion of the flow path substrate 21, and the drive contact portion 46 and the ground contact portion 47 are exposed from the wiring protection film 43. The exposed contact portions 46 and 47 can be connected to the COF 50 described later. The wiring protection film 43 is made of, for example, silicon nitride (SiNx) or the like.

The lead-out wiring 42 is in contact with the insulating film 41 (first layer of the present invention) laminated on the lower side and the wiring protective film 43 (second layer of the present invention) laminated on the upper side, respectively. .. Here, the upper wiring protective film 43 is made of a material having a higher thermal conductivity than the lower insulating film 41. Specifically, the thermal conductivity of SiO2 forming the insulating film 41 is 1 to 1.5 W / (m · K), and the thermal conductivity of SiNx forming the wiring protection film 43 is 20 to 28 W / (m · K). (M · K). In this case, as will be described later, the heat transferred from the driver IC 51 to the lead-out wiring 42 can be positively released to the upper cover member 23.

In the present embodiment, the individual electrode 34 is exposed from the protective film 40 and the like except for the peripheral portion thereof. Therefore, the laminated body of the protective film 40, the insulating film 41, and the wiring protective film 43 hardly hinders the deformation of the individual actuators. Further, at the peripheral edge of the individual electrode 34 in the scanning direction, the lead wiring 40 has one end of the lead on the upper surface of the insulating film 41 and is connected to the individual electrode 34 in the thickness direction. As shown in FIG. 4, the connection with the individual electrode 34 is made through a through hole penetrating the insulating film 41 and the protective film 40.

As shown in FIGS. 2 and 3, one end of the COF 50 is joined to the upper surfaces of the left and right ends of the flow path substrate 21, respectively. A driver IC 51 (driving device of the present invention) is mounted in the middle of each COF 50. The other end of each COF 50 is connected to the control device 7 (see FIG. 1) of the printer 1.

In addition to the ground wiring (not shown), a plurality of drive wirings 52 are formed in the COF 50. Each drive wiring 52 is connected to an output terminal of the driver IC 51. At both ends of the flow path board 21, the drive wiring 52 is connected to the corresponding drive contact portion 46, and the ground wiring is connected to the ground contact portion 47.

The driver IC 51 generates a drive signal based on the control signal from the control device 7, and outputs the drive signal to each piezoelectric element 31. The drive signal is input to the drive contact portion 46 via the drive wiring 52, and is further supplied to the corresponding individual electrodes 34 via the extraction wiring 42. At this time, the potential of the individual electrode 34 changes between a predetermined drive potential and the ground potential. The potential of the common electrode 32 is always maintained at the ground potential.

The operation of each piezoelectric element 31 when a drive signal is supplied from the driver IC 51 will be described. In the state where the drive signal is not supplied, the potential of the individual electrodes 34 is the ground potential, which is the same potential as the common electrode 32. When a driving potential is applied to the individual electrodes 34 from this state, an electric field in the thickness direction acts on the active portion 36 of the piezoelectric body 33 due to the potential difference from the common electrodes 32 arranged opposite to each other. At this time, the active portion 36 extends in the thickness direction and contracts in the plane direction. The vibrating film 30 is combined with the active portion 36 (piezoelectric element 31), and the individual actuator bends so as to be convex toward the pressure chamber 26 side. As a result, the volume of the pressure chamber 26 is reduced and a pressure wave is generated in the pressure chamber 26, so that ink droplets are ejected from the nozzle 24 communicating with the pressure chamber 26.

(Cover member)
As shown in FIGS. 2 to 4, the cover member 23 is arranged on the upper surface of the flow path substrate 21 on which the piezoelectric actuator 22 is formed so as to cover the plurality of piezoelectric elements 31. The cover member 23 has not only a function of covering and protecting the plurality of piezoelectric elements 31 but also a function of an ink storage unit for temporarily storing ink to be supplied to the flow path substrate 21. The cover member 23 is joined to the flow path substrate 21 by a thermosetting adhesive 66. More specifically, after applying the adhesive 66 to either the cover member 23 or the flow path substrate 21, the cover member 23 is pressed against the flow path substrate 21 while heating to join the two.

As shown in FIG. 4, a reservoir 60 for storing ink is formed on the upper portion of the cover member 23. Although only two reservoirs 60 are shown in FIG. 4, in reality, four reservoirs 60 for storing inks of four colors are arranged side by side in the scanning direction. The four reservoirs 60 are sealed by a lid member 65 joined to the upper surface of the cover member 23. Further, the four ink cartridges 15 (see FIG. 1) of the holder 5 supply inks of four colors to the four reservoirs 60, respectively.

Two wall portions 61a and 61b extending in the scanning direction and nine wall portions 62a to 62i extending in the transport direction are formed in the lower portion of the cover member 23. The nine wall portions 62a to 62i are arranged at intervals in the scanning direction. Of the nine wall portions 62a to 62i, the wall portion 62a located at the right end and the wall portion 62e located at the left end are referred to as "outer wall portions", respectively. Further, of the seven wall portions 62b, 62c, 62d, 62f, 62g, 62h, 62i between the two outer wall portions 62a, 62e, the wall portion 62i located at the center is referred to as a "central wall portion". The other wall portion is referred to as an "inner side wall portion".

Each of the nine wall portions 62 is joined to the flow path substrate 21 with one piezoelectric element row 37 sandwiched between the nine wall portions 62 and the other adjacent wall portions 62. Specifically, the outer wall portion 62a on the right side is joined to the region on the right side of the four piezoelectric element groups 38 (eight piezoelectric element rows 37), and the outer wall portion 62e on the left side is the region of the four piezoelectric element groups 38. Joined to the area on the left. The central wall portion 62i is joined to the region between the two central piezoelectric element groups 38y and 38c. The inner side wall portion 62c is joined to the region between the two piezoelectric element groups 38k and 38y on the right side, and the inner side wall portion 62g is joined to the region between the two piezoelectric element groups 38c and 38m on the left side. The remaining inner wall portions 62b, 62d, 62f, 62h are joined to the region between the two piezoelectric element rows 37 for each of the four piezoelectric element groups 38. As a result, the lower portion of the cover member 23 is partitioned by the wall portion 62, and eight accommodation spaces 63 are arranged in the scanning direction. One accommodating space 63 accommodates one piezoelectric element row 37.

As described above, a plurality of ink supply holes 30a are opened in the region between the two piezoelectric element rows 37 of one piezoelectric element group 38 on the upper surface of the flow path substrate 21. On the other hand, as shown in FIG. 4, a plurality of flow path holes 64 are formed in the inner side wall portions 62b (62d, 62f, 62h) joined to the above region of the cover member 23. The ink supply port 30a and the flow path hole 64 have a one-to-one correspondence. The ink stored in the reservoir 60 is supplied to the plurality of pressure chambers 26 arranged in two rows via the plurality of flow path holes 64 and the plurality of ink supply holes 30a, respectively.

The widths of the nine wall portions 62 arranged in the scanning direction are not all the same. Comparing the widths of the wall portions 62, as shown in FIGS. 2 and 3, (widths W1 of the two outer wall portions 62a, 62e)> (widths W2 of the inner side wall portions 62b, 62d, 62f, 62h)> ( The width W3 of the inner side wall portions 62c and 62 g) = (width W4 of the central wall portion 62i). The inner side wall portions 62b, 62d, 62f, and 62h have a smaller actual bonding area with the flow path substrate 21 because a plurality of flow path holes 64 are formed. However, even when the area reduction due to the flow path hole 64 is taken into consideration, there is no change in the magnitude relationship in the joint area between the nine wall portions 62, which is the same as the magnitude relationship in the width. That is, (joint area A1 of the two outer wall portions 62a, 62e)> (joint area A2 of the inner side wall portions 62b, 62d, 62f, 62h)> (joint area A3 of the inner side wall portions 62c, 62g) = (central wall). The joint area A4) of the portion 62i.

As described above, a plurality of extraction wires 42 are drawn out to the right from the four piezoelectric element rows 37 on the right side. Of these, the lead-out wiring 42 drawn from the leftmost piezoelectric element row 37 has a joining region of the inner side wall portion 62d, a joining region of the inner side wall portion 62c, a joining region of the inner side wall portion 62b, and a joining of the outer wall portion 62a. It passes through the regions in order and extends to the outside (right side) of the cover member 23. The more the four joint regions are located on the right side, which is the wiring lead-out side, the larger the number of lead-out wires 42 that pass through. Similarly, a plurality of lead wires 42 are pulled out to the left from the four piezoelectric element rows 37 on the left side. Of these, the lead-out wiring 42 drawn from the rightmost piezoelectric element row 37 has a joining region of the inner side wall portion 62h, a joining region of the inner side wall portion 62g, a joining region of the inner side wall portion 62f, and a joining of the outer wall portion 62e. It passes through the regions in order and extends to the region on the outside (left side) of the cover member 23. Further, the outer joint region has more lead wires 42 crossed.

By the way, the driver IC 51 generates heat when driving the piezoelectric element 31. Part of the heat is transmitted to the flow path substrate 21 via the plurality of lead wires 42, and the temperature of the piezoelectric element 31 and the temperature of the ink in the pressure chamber 26 rise. At that time, if there is a difference in the amount of heat transfer between the plurality of pressure chambers 26 or between the plurality of piezoelectric elements 31, the discharge characteristics will differ among the plurality of nozzles 24. In order to suppress this variation in discharge characteristics, it is effective to dissipate the heat transmitted from the driver IC 51 to the cover member 23 as much as possible. Therefore, in order to realize quick heat dissipation, in the present embodiment, the joining area with the flow path substrate 21 is different between the plurality of wall portions 62 arranged in the wiring lead-out direction.

Regarding the joint area of the four right wall portions 62a to 62d, first, the joint area of the outer wall portion 62a located at the right end with the flow path substrate 21 is larger than the three inner side wall portions 62b, 62c, 62d. .. Here, the junction region between the flow path substrate 21 and the outer wall portion 62a is crossed by the lead wiring 42 from the two piezoelectric element groups 38k and 38y on the right side. That is, since the outer wall portion 62a having a large joining area is joined to the region where the drawer wirings 42 are densely packed, the heat transferred to the drawer wirings 42 can be effectively released to the cover member 23. Further, as far as the three wall portions 62a, 62b, 62c on the right side are concerned, the width W (joint area A) is larger as the wall portion is located on the wiring lead-out side (right side). That is, as the number of the drawer wirings passing through is larger, the wall portion 62 having a large joining area is joined, so that the heat transferred to the drawer wirings 42 can be effectively released to the cover member 23.

From the above viewpoint, the width (joint area) of the inner side wall portion 62d located on the side opposite to the wiring lead-out side is made smaller than the inner side wall portion 62c, and the outer wall portion 62a, the inner side wall portion 62b, and the inner side wall portion are made smaller. The width (joint area) may be reduced in the order of the portion 62c and the inner side wall portion 62d. However, since the inner side wall portion 62d is a wall portion on which a plurality of flow path holes 64 are formed, there is a limit to reducing the width. Therefore, in the present embodiment, the width (joint area) of the inner side wall portion 62d is the same as that of the inner side wall portion 62b, and is larger than that of the inner side wall portion 62c.

The same applies to the four wall portions 62 on the left side, and the joint area of the outer wall portion 62e located at the left end with the flow path substrate 21 is the largest. Further, as far as the three wall portions 62e, 62f, 62g on the left side are concerned, the width W (joint area A) is larger as the wall portion located on the wiring lead-out side (left side) is located.

The central wall portion 62i has two piezoelectric element groups 38k and 38y (the first piezoelectric element group of the present invention) whose wiring pull-out direction is on the right side and two piezoelectric element groups 38c and 38m whose wiring pull-out direction is on the left side. It is arranged between (the second piezoelectric element group of the present invention). That is, the lead-out wiring 42 is not arranged in the joint region of the central wall portion 62i of the flow path substrate 21. Therefore, from the viewpoint of dissipating the heat transmitted through the lead-out wiring 42, it is not necessary to increase the width of the central wall portion 62i so much. Therefore, in the present embodiment, the width W4 of the central wall portion 62i is the same as the width W3 of the inner side wall portions 62c and 62g.

In the present embodiment, since the cover member 23 has a structure having a plurality of inner side wall portions 62b to 62h and a central wall portion 62i in addition to the two outer wall portions 62a and 62e, the cover member 23 is used as a flow path substrate. It is possible to prevent the central portion of the cover member 23 from bending when the cover member 23 is joined. Further, when the cover member 23 is joined with the adhesive 66 while being heated, the cover member 23 may warp and a force in the direction of peeling from the flow path substrate 21 may act on the outer wall portions 62a and 62e. .. Even in this case, since the joint area of the outer wall portions 62a and 62e is larger than that of the inner side wall portions 62b to 62h and the central wall portion 62i, it is possible to prevent the outer wall portions 62a and 62e from peeling off.

As shown in FIG. 4, the lower insulating film 41 and the upper wiring protective film 43 are laminated in contact with the lead wiring 42, respectively, except for the left and right ends of the flow path substrate 21. Further, the wiring protective film 43 (for example, SiNx) is made of a material having a higher thermal conductivity than _{the insulating film 41 (for example, SiO 2).} This makes it easier for the heat transmitted through the driver IC 51 lead-out wiring 42 to escape to the cover member 23.

As shown in FIGS. 2 and 3, a convex portion 67 extending in the transport direction is formed in the joint region (region in which the ink supply hole 30a is not formed) with the inner side wall portions 62c and 62g of the flow path substrate 21. Has been done. A plurality of drawer wirings 42 pass through the joint region, and the convex portion 67 is formed so as to avoid the drawer wirings 42. In other words, a plurality of convex portions 67 extend in the transport direction in a form of being divided by the lead-out wiring 42. Further, with respect to the scanning direction, a plurality of convex portions 67 are arranged at intervals from each other.

When the inner side wall portions 62c and 62g are joined to the flow path substrate 21 by the above-mentioned convex portions 67, the plurality of convex portions 67 arranged in the scanning direction regulate the flow of the adhesive 66 in the scanning direction. The adhesive 66 flows out from the inner side wall portions 62c and 62g to both sides in substantially equal amounts, and the amount itself is small. Therefore, the surplus adhesive 66 does not prevent the deformation of the piezoelectric element approaching. Further, since the surface of the joint region of the flow path substrate 21 has an uneven shape, the effect of increasing the adhesive force between the inner side wall portions 62c and 62g and the flow path substrate 21 can be obtained.

The material of the convex portion 67 is not particularly limited, but the convex portion 67 and the lead wiring 42 are subjected to the same film forming process (for example, sputtering) by using the same conductive material as the lead wiring 42 (for example, gold or aluminum). Etc.). Further, in that case, the height of the convex portion 67 and the thickness of the lead-out wiring 42 can be made equal to each other. The height of the convex portion 67 (thickness of the lead-out wiring 42) is, for example, 1 μm or less. As a result, the height of the joint surface can be made uniform between the joint region of the flow path substrate 21 with the inner side wall portions 62c and 62 g and the joint region with the other wall portions 61 and 62.

As shown in FIG. 2, a convex portion 68 extending in the transport direction is also formed in the joint region of the central wall portion 62i of the flow path substrate 21. Further, with respect to the scanning direction, a plurality of convex portions 68a are arranged side by side at intervals from each other. Therefore, the flow of the adhesive 66 between the two piezoelectric element groups 38 on both sides of the central wall portion 62i can be suppressed. Further, since the surface of the joint region of the flow path substrate 21 has an uneven shape, the adhesive force between the central wall portion 62i and the flow path substrate 21 is enhanced. Similar to the above-mentioned convex portion 67, the convex portion 68 may be formed by using the same conductive material as the drawer wiring 42 and in the same film forming process as the drawer wiring 42.

Since the lead wiring 42 is not arranged in the joint region of the central wall portion 62i of the flow path substrate 21, the convex portion that extends continuously in the transport direction is different from the joint region of the inner side wall portions 62c and 62 g. It is possible to form 68. Specifically, as shown in FIG. 2, the convex portion 68a located at the central portion of the joint region extends continuously in the transport direction, and the length thereof is equal to or longer than the total length of the piezoelectric element group 38. With this configuration, the flow states of the excess adhesive 66 are aligned on both sides of the central wall portion 62i, and the amount of the excess adhesive 66 flowing out can be small. Further, the long convex portion 68a increases the adhesive force between the central wall portion 62i and the flow path substrate 21, and the width of the central wall portion 62i can be changed to a narrower one.

Next, a modified embodiment in which various modifications are made to the embodiment will be described. However, those having the same configuration as that of the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted as appropriate.

1] In the above embodiment, in the joint region of the flow path substrate 21 with the wall portion 62, the lead wiring 42 extends in a direction parallel to the scanning direction, but intersects the scanning direction at an angle of less than 90 degrees. May extend to. For example, in FIG. 5, in the joint region of the flow path substrate 21 with the outer wall portion 62a, the lead wiring 42 extends so as to cross in a direction intersecting the scanning direction at an angle θ. In this way, the drawer wiring 42 extends so as to diagonally cross the joint region, so that the contact length of the drawer wiring 42 with the outer wall portion 62a becomes long. This makes it easier for the heat transferred from the driver IC 51 to the lead-out wiring 42 to escape to the cover member 23. In the joint region with the wall portion 62 other than the outer wall portion 62a, the lead wiring 42 may extend so as to diagonally cross. Further, in the joint region of a certain wall portion 62, not all the drawer wirings 42 need to extend diagonally, and only a part of the drawer wirings 42 may extend diagonally.

In FIG. 5, a plurality of lead-out wirings 42 are inclined and extended so as to be closer to the center in the transport direction, and as a result, the arrangement lengths of the contact portions 46 and 47 are shortened. That is, FIG. 5 shows a form in which electrical and mechanical connectivity can be ensured even if the arrangement lengths of the contact portions 46 and 47 are short with respect to the total length of the piezoelectric element group 38 in the transport direction. It shows. On the other hand, when there is concern about ensuring the above-mentioned connectivity, the lead-out wiring 42 may be arranged so as to be inclined in a direction away from the center in the transport direction and cross the connection region.

2] When there are a plurality of inner side wall portions as in the above embodiment, the magnitude relationship of the joint area between the plurality of inner side wall portions can be appropriately changed according to the configuration of each wall portion. .. For example, in FIG. 3, the joint area of the three inner side wall portions 62b, 62c, 62d may be larger as it is located on the wiring lead-out side (right side). That is, the relationship may be (joint area of outer wall portion 62a)> (joint area of inner side wall portion 62b)> (joint area of inner side wall portion 62c)> (joint area of inner side wall portion 62d). Alternatively, the joint areas of the three inner side wall portions 62b, 62c, and 62d may all be the same.

3] The number of piezoelectric element rows, the number of wall portions of the cover member, the pull-out direction of the lead-out wiring 42, and the like can be changed as follows.

For example, in the above-described embodiment, a plurality of lead-out wirings 42 extend to the left and right on the upper surface of the flow path substrate 71. On the other hand, as shown in FIG. 6, the lead-out wirings 42 of the plurality of piezoelectric elements 31 may all be pulled out in the same direction. In FIG. 6, all the lead-out wirings 42 are pulled out to the right. The width (joint area) of the outer wall portion 72a on the wiring extraction side (right side) of the cover member 70 is the inner side wall portions 72b, 72c, 72d located on the left side of the outer wall portion 72a, and the outer wall portion. It is larger than the width (joint area) of 72e.

Further, as shown in FIGS. 7 and 8, the cover member 80 may have no inner side wall portion, and the cover member 80 may have only two wall portions 82a and 82b on both the left and right sides. In FIGS. 7 and 8, a plurality of extraction wires 42 are drawn out to the right from the plurality of piezoelectric elements 31 on the upper surface of the flow path substrate 81. On top of that, the width of the right wall portion 82a located on the wiring extraction side is larger than the width of the left wall portion 82b located on the side opposite to the wiring extraction side.

4] The cover member only needs to have a function of covering at least the piezoelectric element 31, and it is not essential that the cover member also has a function of temporarily storing ink as in the above-described embodiment. That is, the reservoir may not be formed on the cover member. In this case, since ink is supplied to each pressure chamber 26 from a member other than the cover member, the flow path hole 64 (see FIG. 4) is not formed in the wall portion of the cover member.

The above-described embodiments and modifications thereof apply the present invention to an inkjet head that ejects ink onto recording paper to print an image or the like, but are used for various purposes other than printing images or the like. The present invention can also be applied to a liquid discharge device. For example, the present invention can be applied to an industrial liquid discharge device that discharges a conductive liquid onto a substrate to form a conductive pattern on the surface of the substrate.

4 Inkjet head 20 Nozzle plate 21 Flow path substrate 22 Piezoelectric actuator 23 Cover member 24 Nozzle 26 Pressure chamber 31 Piezoelectric element 37 Piezoelectric element row 38 Piezoelectric element group 41 Insulation film 42 Drawer wiring 43 Wiring protection film 51 Driver IC
62a, 62e Outer side wall 62b, 62c, 62d, 62f, 62g, 62h Inner side wall 62i Central wall 66 Adhesive 67 Convex 68 Convex 70 Cover member 71 Flow path board 72a to 72e Wall 80 Cover member 81 Flow Road boards 82a, 82b Walls

Claims (7)

A flow path structure having a plurality of nozzles arranged in the first direction and a plurality of pressure chambers arranged in the first direction corresponding to the plurality of nozzles.
In the flow path structure, a plurality of piezoelectric elements arranged in the first direction corresponding to the plurality of pressure chambers,
A cover member which is arranged side by side in the second direction orthogonal to the first direction, has a plurality of wall portions joined to the flow path structure, and covers the plurality of piezoelectric elements.
A plurality of lead wires drawn from the plurality of piezoelectric elements, passing through the joint region between the wall portion and the flow path structure, and extending to the outside of the wall portion.
A drive device that is electrically connected to the plurality of lead wires is provided.
The plurality of piezoelectric elements include a first piezoelectric element row and a second piezoelectric element row arranged adjacent to each other in the second direction.
The plurality of lead wirings extend from the first piezoelectric element row and the second piezoelectric element row in a direction away from each other in the second direction.
The central wall portion, which is the wall portion, is arranged between the first piezoelectric element row and the second piezoelectric element row.
A head having a concave-convex shape on a surface that defines a joint region between the central wall portion and the flow path structure. Of the channel structure, Oite the region central wall portion is joined, the concave-convex shape, the convex portions and a plurality of protruding in a direction perpendicular to the first direction and the second direction of the convex portion The head according to claim 1, wherein the head is formed by a concave portion formed between the concave portions, and the repetition of the convex portion and the concave portion having the concave-convex shape is formed so as to extend in the first direction. .. The head according to claim 2, wherein a plurality of the concave-convex shapes formed by repeating the convex portion and the concave portion extending in the first direction are arranged at intervals in the second direction. The convex portion having the concave-convex shape protrudes from the surface of the flow path structure, is formed of the same conductive material as the lead-out wiring, and uses the surface of the flow path structure as a reference for height. The head according to claim 2 or 3, wherein the height of the convex portion in the first direction and the direction orthogonal to the second direction is equal to the thickness of the lead-out wiring. Of the concave-convex shape , the repetition of the convex portion and the concave portion of the concave-convex shape located at the central portion in the second direction of the joint region of the central wall portion is the first piezoelectric element adjacent to the concave-convex shape. The head according to claim 2, wherein the head has a length equal to or greater than the total length in the first direction of the row. A first layer is laminated in contact with the lead-out wiring on the flow path structure side of the plurality of lead-out wirings.
A second layer is laminated in contact with the lead-out wiring on the cover member side of the plurality of lead-out wirings.
The head according to any one of claims 1 to 5, wherein the second layer is made of a material having a higher thermal conductivity than the first layer. Wherein at least a portion of the plurality of lead wires, cross the junction region between the channel structure and the wall portion located on the edge of one side in the second direction, in a direction crossing the second direction The head according to any one of claims 1 to 6.

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