JP7047312B2 - Liquid discharge head - Google Patents

Description

The present invention relates to a liquid ejection head that ejects a liquid such as ink toward a medium.

As a liquid ejection device, an inkjet head of an inkjet printer that ejects ink to a recording medium to form an image while moving relative to the recording medium is known. For example, in the inkjet printer shown in Patent Document 1, an inkjet head having a piezoelectric body in which a plurality of piezoelectric material layers (ceramic sheets) are laminated is disclosed.

JP-A-2007-324492

In the inkjet head of Patent Document 1, due to the formation of a plurality of individual surface electrode rows in the uppermost piezoelectric material layer, the uppermost piezoelectric material layer is warped when the piezoelectric material layer is fired. It is known that deformation occurs. In Patent Document 1, through holes are formed in the individual surface electrodes in order to reduce the warp deformation that occurs in the uppermost piezoelectric material layer.

An object of the present invention is to reduce warpage deformation that occurs in the piezoelectric body of an inkjet head.

According to the aspect of the present invention, it is a piezoelectric body in which a plurality of piezoelectric layers are laminated, and the first end and the second end separated in the first direction orthogonal to the stacking direction of the plurality of piezoelectric layers.
A plurality of individual electrodes formed along the first surface, which is a surface orthogonal to the stacking direction, and
A piezoelectric body comprising a first common electrode formed along a second surface that is orthogonal to the stacking direction and whose position in the stacking direction is different from the position of the first surface in the stacking direction. ,
The plurality of individual electrodes constitute a plurality of individual electrode rows arranged with a gap between the first end and the second end.
The plurality of individual electrode rows have a first individual electrode row and a second individual electrode row adjacent to the first individual electrode row in the first direction, and the first individual electrode row has the first direction. Located between the first end and the second individual electrode row in
The plurality of individual electrodes constituting the first individual electrode row are arranged in a direction orthogonal to the stacking direction and along a second direction intersecting with the first direction.
The first common electrode includes a first extending portion extending along the second direction so as to pass a position between the first individual electrode row and the second individual electrode row in the first direction, and the above-mentioned first common electrode. A plurality of first projecting portions projecting from the first extending portion toward the first end are provided.
Each first protrusion partially overlaps with one of the plurality of individual electrodes constituting the first individual electrode row in the stacking direction.
The first extending portion is provided with a liquid discharge head characterized in that a plurality of through holes are formed.

According to the above configuration, the first common electrode has a first extending portion and a plurality of first protruding portions. On the second surface where the first common electrode is formed, the magnitude of the compressive stress remaining in the region where the first extending portion is formed remains in the region where the plurality of first protruding portions are formed. It is larger than the magnitude of the compressive stress and the compressive stress remaining in the region where the first common electrode is not formed. Due to the fact that the compressive stress remaining on the second surface differs from place to place, the piezoelectric body is deformed in a wavy manner. On the other hand, by forming a through hole in the first extending portion, the compressive stress remaining in the region where the first extending portion is formed on the second surface where the first common electrode is formed. The size can be reduced. As a result, it is possible to reduce the deformation of the piezoelectric body in a wavy manner.

It is a top view which shows the outline of the inkjet printer 1 which concerns on this embodiment. It is a schematic diagram of the inkjet head 5 and the wiring member 50 which concerns on this embodiment. It is a schematic exploded view of the laminated body which concerns on this embodiment. It is a schematic cross-sectional view of the inkjet head which concerns on this embodiment, (a) is a schematic cross-sectional view in a scanning direction, and (b) is a schematic cross-sectional view in a transport direction. It is a top view of the upper piezoelectric layer 140 which concerns on this embodiment. It is a top view of the intermediate piezoelectric layer 240 which concerns on this embodiment. It is a top view of the lower piezoelectric layer 340 which concerns on this embodiment. (A) is a schematic diagram showing the overlap of the upper piezoelectric layer 140 and the intermediate piezoelectric layer 240 according to the present embodiment, and (b) is a schematic diagram showing the overlap of the upper piezoelectric layer 140 and the lower piezoelectric layer 340. It is a top view of the lower piezoelectric layer 340 which concerns on the modified embodiment. It is a top view of the lower piezoelectric layer 340 which concerns on another modified embodiment. (A) to (c) are schematic views for explaining the wavy deformation generated in the piezoelectric body.

<Outline configuration of printer>
An embodiment of the present invention will be described. As shown in FIG. 1, the inkjet printer 1 mainly includes a platen 2, a carriage 3, a carriage drive mechanism 4, an inkjet head 5, a transport mechanism 6, a controller 7, and an ink supply unit 8. There is.

The recording paper 100, which is a recording medium, is placed on the upper surface of the platen 2. The carriage 3 is configured to reciprocate in the left-right direction (hereinafter, also referred to as a scanning direction) along the two guide rails 10 and 11 in the region facing the platen 2 by the carriage drive mechanism 4. The carriage drive mechanism 4 includes a belt 12, two rollers 13 arranged so as to sandwich the platen 2 on both sides of the platen 2 in the scanning direction, and a carriage drive motor 14. A belt 12 is connected to the carriage 3. The belt 12 is stretched between two rollers 13 arranged apart from each other in the scanning direction so as to form an oval ring long in the scanning direction when viewed from above. As shown in FIG. 1, the roller 13 on the right side is connected to the rotating shaft of the carriage drive motor 14. By rotating the carriage drive motor 14, the belt 12 can be rotated around the two rollers 13. Along with this, the carriage 3 connected to the belt 12 can be reciprocated in the scanning direction.

The inkjet head 5 is attached to the carriage 3 and reciprocates in the scanning direction together with the carriage 3. The ink supply unit 8 includes four ink cartridges 17 in which inks of four colors (black, yellow, cyan, magenta) are stored, a cartridge holder 18 in which the four ink cartridges 17 are mounted, and a tube (not shown). To prepare for. The inkjet head 5 and the four ink cartridges 17 are connected to each other through a tube (not shown). As a result, the four colors of ink are supplied from the ink supply unit 8 to the inkjet head 5.

A plurality of nozzles 23 are formed on the lower surface of the inkjet head 5 (the surface on the other side of the paper surface in FIG. 1) (see FIG. 3). The plurality of nozzles 23 eject the ink supplied from the ink cartridge 17 toward the recording paper 100 placed on the platen 2.

The transport mechanism 6 has two transport rollers 18 and 19 arranged so as to sandwich the platen 2 in the front-rear direction. 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 18 and 19.

The controller 7 includes a ROM (Read Only Memory), a RAM (Random Access Memory), an ASIC (Application Specific Integrated Circuit) including a control circuit, and the like. The controller 7 executes various processes such as printing on the recording paper 100 by the ASIC according to the program stored in the ROM. For example, in the printing process, the controller 7 controls the inkjet head 5, the carriage drive motor 14, and the like based on a printing command input from an external device such as a PC to print an image on the recording paper 100. Specifically, the ink ejection operation of ejecting ink while moving the inkjet head 5 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 18 and 19 are alternately performed. Let me do it.

The inkjet head 5 mainly includes a flow path unit 20, a diaphragm 30, a piezoelectric body 40, and a wiring member 50 (see FIG. 2). As shown in FIGS. 2 and 3, the flow path unit includes five metal plates 21A to 21E and a nozzle plate 22. Further, a diaphragm 30 is joined on the metal plate 21A of the flow path unit 20. In the following description, the combination of the flow path unit and the diaphragm 30 is referred to as a laminated body 60. That is, as shown in FIG. 3, the laminated body 60 has a diaphragm 30, five metal plates 21A to 21E, and a nozzle plate 22, and these plates are laminated and joined in this order. Is. In the following description, the direction in which these plates are laminated in the laminated body 60 is referred to as a stacking direction.

The diaphragm 30 is a substantially rectangular metal plate that is long in the transport direction. The metal plates 21A to 21E and the nozzle plate 22 are also substantially rectangular plates having the same planar shape. As shown in FIGS. 2 and 3, four openings 31a to 31d serving as ink supply ports for supplying ink to the manifold described later are formed at the end of the diaphragm 30 in the transport direction. .. The four openings 31a to 31d are arranged side by side in the scanning direction (left-right direction). The opening 31a is an ink supply port for yellow ink, the opening 31b is an ink supply port for magenta ink, the opening 31c is an ink supply port for cyan ink, and the opening 31d is an ink supply port for black ink. Is. There are three manifolds for black ink, and the opening 31d is a supply port for supplying black ink to the three manifolds. On the other hand, there is one manifold for color inks (cyan, magenta, and yellow inks), and the openings 31a to 31c are supply ports for supplying one of the color inks to one manifold. Is. Therefore, the area of the opening 31d is larger than the area of the openings 31a to 31c.

The plate 21A is a metal plate in which openings that function as a plurality of pressure chambers 26 are regularly formed. Further, openings are formed at positions overlapping the four openings 31a to 31d of the diaphragm 30. The plurality of pressure chambers 26 constitute pressure chamber rows 25 arranged in the transport direction at an arrangement pitch P, and 12 such pressure chamber rows 25 are formed. The 12 rows of pressure chamber rows 25 are arranged side by side in the scanning direction (left-right direction).

Of the 12 rows of pressure chambers 25, 6 rows are pressure chamber rows 25 for color ink, and the remaining 6 rows are pressure chamber rows 25 for black ink. As shown in FIG. 2, the six rows of pressure chamber rows 25 for black ink are provided so as to be aligned with the openings 31d in the transport direction. The 6-row color ink pressure chamber row 25 has 2 rows of cyan ink pressure chamber rows 25, 2 rows of magenta ink pressure chamber rows 25, and 2 rows of yellow ink pressure chamber rows 25. are doing. The two rows of pressure chamber rows 25 for cyan ink are provided so as to be aligned with the openings 31c in the transport direction. The two rows of pressure chamber rows 25 for magenta ink are provided so as to be aligned with the openings 31b in the transport direction. The two rows of pressure chamber rows 25 for yellow ink are provided so as to be aligned with the openings 31a in the transport direction.

Between the two rows of pressure chamber rows 25 for cyan ink, the positions of the pressure chambers 26 in the transport direction are offset by half (P / 2) of the arrangement pitch P of each pressure chamber row 25. The same applies to the two rows of magenta ink pressure chamber rows 25 and the two rows of yellow ink pressure chamber rows 25. In the six rows of pressure chamber rows 25 for black ink, the positions of the pressure chambers 26 in the transport direction are shifted by half (P / 2) of the arrangement pitch P of each pressure chamber row 25 (P / 2). It has three pairs of pressure chamber rows 25). Although not clearly shown in FIG. 2, the three pairs of pressure chamber rows 25 are arranged so as to be offset from each other by 1/3 of the arrangement pitch P in the transport direction. Therefore, as a whole, the positions of the pressure chambers 26 in the transport direction of the six pressure chamber rows 25 are displaced from each other by 1/6 of the arrangement pitch P of each pressure chamber row 25.

In the plate 21B, a communication hole 28a forming a flow path leading from the manifold 27 (common ink chamber) described later to each pressure chamber 26 and a communication hole 28b forming a communication path leading from each pressure chamber 26 to each nozzle 23 described later are formed. Is formed. A communication passage 28c that connects the pressure chamber 26 and the manifold 27 is formed as a recess on the upper surface of the plate 21C. Further, the plate 21C is formed with a communication hole 28d forming a flow path leading from the manifold 27 to the pressure chamber 26 and a communication hole 28e forming a communication flow path leading from the pressure chamber 26 to the nozzle 23, respectively. Further, openings are formed in the plates 21B and 21C at positions overlapping with the four openings 31a to 31d of the diaphragm 30. Through holes 29a and 29b forming the manifold 27 are formed in the plates 21D and 21E, and communication holes 29c and 29d forming a flow path leading from the pressure chamber 26 to the nozzle 23 are formed, respectively.

The nozzle plate 22 is a plate of synthetic resin (for example, polyimide resin), and the nozzle 23 is formed corresponding to the pressure chamber 26 formed in the plate 21A.

By laminating and joining these diaphragms 30, plates 21A to 21E and nozzle plates 22, the manifold reaches the nozzle 23 via the pressure chamber 26 as shown in FIGS. 4A and 4B. A plurality of flow paths are formed. At the same time, an ink supply flow path for supplying ink to the manifold 27 is also formed.

Since the diaphragm 30 and the plates 21A to 21E are metal plates, they can be joined by metal diffusion joining. Further, since the nozzle plate 22 is a resin plate, it is bonded to the plate 21E by an adhesive or the like instead of metal diffusion bonding. The nozzle plate 22 may be a metal plate, and in that case, it can be joined by metal diffusion joining like other plates. Alternatively, all the plates may be joined with an adhesive or the like.

<Piezoelectric body 40>
For example, as shown in FIGS. 2 and 3, the piezoelectric body 40 is arranged on the diaphragm 30. The piezoelectric body 40 has a substantially rectangular planar shape. As shown in FIGS. 4A and 4B, a plurality of piezoelectric elements 401 are formed in the piezoelectric body 40. The plurality of piezoelectric elements 401 are provided corresponding to the plurality of pressure chambers 26, respectively. Each piezoelectric element 401 cooperates with the diaphragm 30 to change the volume of the corresponding pressure chamber 26. As a result, each piezoelectric element 401 cooperates with the diaphragm 30 to apply pressure to the ink in the corresponding pressure chamber 26, and ink the energy for ejecting the ink from the nozzle 23 communicating with the pressure chamber 26. Is given to.

Hereinafter, the configuration of the piezoelectric body 40 will be described. As shown in FIGS. 4A and 4B, the piezoelectric body 40 includes three piezoelectric layers (upper piezoelectric layer 140, intermediate piezoelectric layer 240, lower piezoelectric layer 340), individual electrodes (upper electrodes) 141, and intermediate electrodes. It has a common electrode (intermediate electrode) 241 and a lower common electrode (lower electrode) 341. The lower piezoelectric layer 340, the intermediate piezoelectric layer 240, and the upper piezoelectric layer 140 are laminated in this order on the diaphragm 30. The three piezoelectric layers 140, 240, and 340 are made 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 three piezoelectric layers 140, 240, and 340 may be formed of a lead-free piezoelectric material that does not contain lead. A lower common electrode 341 is arranged on the upper surface of the lower piezoelectric layer 340, an intermediate common electrode 241 is arranged on the upper surface of the intermediate piezoelectric layer 240, and an individual electrode 141 is arranged on the upper surface of the upper piezoelectric layer 140. ..

In the following description, both ends of the upper piezoelectric layer 140 in the scanning direction are referred to as ends 140L and 140R, and both ends in the transport direction are referred to as ends 140U and 140D (see FIG. 5). Both ends of the intermediate piezoelectric layer 240 in the scanning direction are referred to as ends 240L and 240R, and both ends in the transport direction are referred to as ends 240U and 240D (see FIG. 6). Both ends of the lower piezoelectric layer 340 in the scanning direction are referred to as end portions 340L and 340R, and both ends in the transport direction are referred to as end portions 340U and 340D (see FIG. 7).

As shown in FIG. 5, six through holes 181 filled with a conductor such as solder are formed at the end 140L of the upper piezoelectric layer 140 in the scanning direction, and the conductor in the through holes 181 is formed. Is conductive with the intermediate common electrode 241 (extended portion 243 described later (see FIG. 6)) formed on the upper surface of the intermediate piezoelectric 240. Further, a terminal 181A conducting to the conductor in the through hole 181 is formed on the upper surface of the upper piezoelectric layer 140, and a predetermined potential (for example, 24V) is formed from the driver IC 52 to the intermediate common electrode 241 through the FPC 51 described later. ) Can be supplied. Similarly, six through holes 180 filled with a conductor such as solder are also formed at the end 140R of the upper piezoelectric layer 140 in the scanning direction. As shown in FIG. 6, six through holes 280 filled with a conductor such as solder are formed at positions of the end 240R of the intermediate piezoelectric layer 240 in the scanning direction and overlapping with the through holes 180 in the stacking direction. ing. The conductor in the through hole 280 is conductive with the lower common electrode 341 (extended portion 343 described later (see FIG. 7)). Further, as shown in FIG. 5, on the upper surface of the upper piezoelectric layer 140, a terminal 180A conducting the through hole 280 and the conductor in the through hole 180 is formed, and the terminal 180A is formed with respect to the lower common electrode 341. A predetermined potential (for example, 0V) can be supplied from the driver IC 52 through the FPC 51 described later.

<Individual electrode 141>
As shown in FIGS. 4A and 4B, a plurality of individual electrodes 141 are formed on the upper surface of the upper piezoelectric layer 140 at positions corresponding to the plurality of pressure chambers 26, respectively. The individual electrode 141 is made of, for example, platinum (Pt) or iridium (Ir). As shown in FIG. 5, 12 rows of individual electrode rows 150 are formed corresponding to 12 rows of pressure chamber rows 25. The 12 rows of individual electrode rows 150 are arranged in the scanning direction. Each individual electrode row 150 of each individual electrode row includes 37 individual electrodes 141 arranged at a predetermined pitch P in the transport direction. Of the 12 individual electrode rows 150, the 1st and 2nd, 3rd and 4th, 5th and 6th, counting from the one closest to the end 140L of the upper piezoelectric layer 140 in the scanning direction (horizontal direction). The 7th and 8th, 9th and 10th, 11th and 12th individual electrode rows 150 form a pair of individual electrode rows, respectively. In the following description, in the scanning direction, the nth one counting from the one closest to the end 140L of the upper piezoelectric layer 140 is simply referred to as the nth from the left. Similarly, in the intermediate piezoelectric layer 240 and the lower piezoelectric layer 340, the one located at the nth position from the one closest to the end 240L (see FIG. 6) of the intermediate piezoelectric layer 240 in the scanning direction, and the lower piezoelectric layer 340. The ones closest to the end portion 340L (see FIG. 7A) and are in the nth position are all called the nth position from the left. Between the pairs of the individual electrode rows 150, the positions of the individual electrodes 141 in the transport direction are deviated by half (P / 2) of the arrangement pitch P of each individual electrode row 150. Further, the pairs of the 7th and 8th, 9th and 10th, and 11th and 12th individual electrode rows 150 from the left are displaced from each other by 1/3 of the arrangement pitch P in the transport direction. Therefore, in the 7th and 8th, 9th and 10th, 11th and 12th individual electrode rows 150 from the left, the position of the individual electrode 141 in the transport direction is the arrangement pitch P of each individual electrode row 150. It is off by 1/6 of.

Of the 12 individual electrode rows 150, the pair of the 1st and 2nd, 3rd and 4th, 5th and 6th individual electrode rows 150 from the left are the pressure chamber row 25 for cyan ink and the magenta, respectively. It corresponds to the pressure chamber row 25 for ink and the pressure chamber row 25 for yellow ink. Further, the pair of three individual electrode rows 7th and 8th, 9th and 10th, and 11th and 12th from the left correspond to the pressure chamber row 25 for black ink.

Each individual electrode 141 has a wide portion 142 having a rectangular planar shape (an example of the first portion) and a narrow portion 143 extending from the wide portion 142 in either the left-right direction (scanning direction) (an example of the second portion). ) And. Each narrow portion 143 is formed with a bump (not shown) that is electrically joined to a contact (not shown) provided on the FPC 51 of the wiring member 50 described later. As shown in FIG. 5, among the 12 rows of individual electrode rows 150, the individual electrodes 141 constituting the first, third, fifth, eighth, tenth, and twelfth individual electrode rows 150 from the left The narrow portion 143 extends in the scanning direction from the end portion 142R of the wide portion 142 in the scanning direction toward the end portion 140R of the upper piezoelectric layer 140. Of the 12 rows of individual electrode rows 150, in the individual electrodes 141 constituting the second, fourth, sixth, seventh, ninth, and eleventh individual electrode rows 150 from the left, in the scanning direction of the wide portion 142. The narrow portion 143 extends in the scanning direction from the end portion 142L toward the end portion 140L of the upper piezoelectric layer 140. The narrow portion 143 extends to the opposite side in the scanning direction from the nozzle formed in the corresponding pressure chamber 26 (see FIG. 4A). That is, in the pressure chambers 26 constituting the first, third, fifth, eighth, tenth, and twelfth pressure chamber rows 25 from the left, the piezoelectric layer above the center of each pressure chamber 26 in the scanning direction. The nozzle 23 is formed at a position close to the end 140L of the 140. In the pressure chambers 26 constituting the second, fourth, sixth, seventh, ninth, and eleventh pressure chamber rows 25 from the left, the piezoelectric layer 140 above the center in the scanning direction of each pressure chamber 26 The nozzle 23 is formed at a position close to the end portion 140R.

Of the individual electrode rows 150 adjacent to each other in the scanning direction, (1) the first individual electrode row 150 from the left and the second individual electrode row 150 from the left, and (2) the third individual electrode row 150 from the left and the left. 4th individual electrode row 150 from the left, (3) 5th individual electrode row 150 from the left and 6th individual electrode row 150 from the left, (4) 8th individual electrode row 150 from the left and 9 from the left. The second individual electrode row 150, (5) the tenth individual electrode row 150 from the left and the eleventh individual electrode row 150 from the left have narrow portions 143 of the individual electrodes 141 constituting the individual electrode row 150, respectively. , Are arranged so as to face each other in the scanning direction. Therefore, the size of the interval (L1) in the scanning direction of the wide portion 142 of the individual electrodes 141 constituting these two individual electrode rows 150 is such that the narrow portions 143 do not face each other in the scanning direction. It is larger than the size of the interval (L2) in the scanning direction of the wide portion 142 of the individual electrodes 141 constituting the 150. The size (L3) of the interval in the scanning direction of the wide portion 142 of the individual electrode row 150 constituting the sixth individual electrode row 150 from the left and the individual electrode row 141 constituting the seventh individual electrode row 150 from the left is larger than that of L1 and L2. Is even bigger. This is because the 1st to 6th individual electrode rows 150 from the left correspond to the pressure chamber row 25 for color ink, and the 7th to 12th individual electrode rows 150 from the left correspond to the pressure chamber row 25 for black ink. This is due to the fact that it corresponds to 25.

Dummy electrodes 171 arranged between the 6th individual electrode row 150 from the left and the 7th individual electrode row 150 from the left in the scanning direction at the same arrangement pitch P as the arrangement pitch P of the individual electrodes 141 in the transport direction. A dummy electrode row 170 configured by the above is provided. The dummy electrode 171 is made to correspond to the wide portion 142 of the individual electrode 141, and the size and shape of the dummy electrode 171 are substantially the same as the size and shape of the wide portion 142 of the individual electrode 141. be. Since the dummy electrode 171 is not supplied with the potential from the driver IC 51, the dummy electrode 171 is not provided with a portion corresponding to the narrow portion 143 of the individual electrode 141. The size of the distance between the wide portion 142 of the individual electrode 141 constituting the sixth individual electrode row 150 from the left and the dummy electrode 171 in the scanning direction, and the wide portion of the individual electrode 141 constituting the seventh individual electrode row 150 from the left. The magnitude of the distance between the portion 142 and the dummy electrode 171 in the scanning direction is L1.

<Intermediate common electrode 241>
As shown in FIGS. 4A and 4B, an intermediate common electrode 241 is formed on the upper surface of the intermediate piezoelectric layer 240. As shown in FIG. 6, the intermediate common electrode 241 has an extending portion 242 extending in the scanning direction (left-right direction) so as to cover the end portion 240U in the transport direction of the intermediate piezoelectric layer 240, and the intermediate piezoelectric layer 240. An extending portion 243 extending in the transport direction so as to cover the end portion 240L in the scanning direction, and six extending in the transport direction from the extending portion 242 toward the end portion 240D in the transport direction of the intermediate piezoelectric layer 240. It has an extending portion 244 of the above and a plurality of protruding portions 245 protruding from each extending portion 244 on both sides in the scanning direction. Further, a plurality of protruding portions 245 also protrude from the extending portion 243 toward the end portion 240R of the intermediate piezoelectric layer 240 in the scanning direction.

The extending portion 242 and the extending portion 243 are located at positions that do not overlap with the pressure chamber 26 and the individual electrode 141 in the stacking direction. As shown in FIG. 8A, the extending portion 244 has two individual electrode rows adjacent to each other in the scanning direction so as not to overlap the wide portion 142 of the individual electrode 141 constituting the individual electrode row 150 in the stacking direction. It extends in the transport direction between the wide portions 142 of the individual electrodes 141 constituting the 150. In FIG. 6, of the six extending portions 244, the first extending portion 244 from the left passes between the wide portions 142 constituting the second and third individual electrode rows 150 from the left in the scanning direction. It extends in the transport direction. The second extending portion 244 from the left side extends in the transport direction so as to pass between the wide portions 142 constituting the fourth and fifth individual electrode rows 150 from the left in the scanning direction. The third extending portion 244 from the left side passes between the wide portion 142 constituting the sixth individual electrode row 150 from the left and the dummy electrode 171 constituting the dummy electrode row 170 in the scanning direction. It is postponed. The fourth extending portion 244 from the left side extends in the transport direction so as to pass between the wide portions 142 constituting the seventh and eighth individual electrode rows 150 from the left in the scanning direction. The fifth extending portion 244 from the left side extends in the transport direction so as to pass between the wide portion 142 constituting the ninth and tenth individual electrode rows 150 from the left in the scanning direction. The sixth extending portion 244 from the left side extends in the transport direction so as to pass between the wide portion 142 constituting the eleventh and twelfth individual electrode rows 150 from the left in the scanning direction.

The third extending portion 244 from the left side is located at the boundary between the pressure chamber row 25 for color ink and the pressure chamber row 25 for black ink, and is located between the pressure chamber rows 25 in the scanning direction as described above. Due to the wider spacing, it is wider than the other extension 244. The widths of the remaining five extension 244s are the same. Regarding the five extending portions 244 excluding the third extending portion 244 from the left, the individual electrodes 141 constituting the two individual electrode rows 150 sandwiching each extending portion 244 in the scanning direction are narrow in the scanning direction. The portions 143 are arranged so as to extend to the opposite side. That is, with respect to the five extending portions 244 excluding the third extending portion 244 from the left, the scanning of the wide portion 142 of the individual electrodes 141 constituting the two individual electrode rows 150 sandwiching each extending portion 244 in the scanning direction. The magnitude of the interval in the direction is L2. In line with this, the widths of the five extending portions 244 excluding the third extending portion 244 from the left in the scanning direction are also L2.

Next, the positional relationship between the pressure chamber 26, the individual electrodes 141, and the intermediate common electrode 241 will be described with reference to FIG. 8 (a). In FIG. 8A, four rows of individual electrodes arranged in the scanning direction are shown, but here, the individual electrodes included in the second row of individual electrodes from the left in FIG. 8A. The positional relationship between 141 and the pressure chamber 26 and the intermediate common electrode 241 overlapping in the stacking direction will be described as an example. In order to make the drawings easier to see, the intermediate common electrode 241 and the conductor layer 260 formed in the intermediate conductor layer 240 are shown by solid lines, and the pressure chamber 26, the individual electrodes 141, and the like are shown by dotted lines.

The length of the pressure chamber 26 in the scanning direction is longer than the length of the wide portion 142 of the individual electrode 141 in the scanning direction. The length of the entire individual electrode 141 including the wide portion 142 and the narrow portion 143 in the scanning direction is longer than the length of the pressure chamber 26 in the scanning direction. The length of the protrusion 245 of the intermediate common electrode 241 in the scanning direction is substantially the same as the length of the wide portion 142 of the individual electrode 141 in the scanning direction.

The nozzle 23 is located closer to the end 26R than the end 26L of the pressure chamber in the scanning direction in the scanning direction. The end portion 26R of the pressure chamber 26 is located between the end portion 244L and the end portion 244R of the extending portion 244 in the scanning direction in the scanning direction. The end portion 26L of the pressure chamber 26 is located between the end portion 142L of the wide portion 142 and the end portion 143L of the narrow portion 143 in the scanning direction in the scanning direction. The end portion 245L of the protrusion 245 of the intermediate common electrode 241 in the scanning direction and the end portion 142L of the wide portion 142 are at substantially the same position in the scanning direction. The end portion 141R of the wide portion 142 of the individual electrode 141 in the scanning direction, the end portion 244L of the extending portion 244, and the nozzle 23 are at substantially the same positions in the scanning direction.

The center position of the protrusion 245 of the intermediate common electrode 241 in the transport direction, the center position of the pressure chamber 26 in the transport direction, and the center position of the wide portion 142 of the individual electrode 141 in the transport direction are substantially the same in the transport direction. .. The length of the pressure chamber 26 in the transport direction is longer than the length of the protrusion 245 of the intermediate common electrode 241 in the transport direction, and the ratio of these lengths is about 2: 1. Therefore, both ends of the pressure chamber 26 in the transport direction (about 1/4 of the length of the pressure chamber in the transport direction) do not overlap with the protruding portion 245 of the intermediate common electrode 241 in the stacking direction. Further, the length of the wide portion 142 of the individual electrode 141 in the transport direction is longer than the length of the pressure chamber 26 in the transport direction.

<Conductor layer 260>
As shown in FIG. 6, a plurality of protrusions 245 protruding in the scanning direction from the first extending portion 244 from the left toward the end 240R in the scanning direction, and the second extending portion 244 from the left. Two rows of conductor layer rows 270 extending in the transport direction are arranged between the plurality of protrusions 245 protruding in the scanning direction toward the end portion 240L. The two conductor layer rows 270 are aligned in the scanning direction. Each conductor layer row 270 is composed of a plurality of conductor layers 260 arranged at an arrangement pitch P in the transport direction. In the two rows of conductor layer rows 270, the positions of the conductor layers 260 in the transport direction are deviated by half (P / 2) of the arrangement pitch P of each conductor layer row 270. It should be noted that each conductor layer 260 is not in contact with the other conductor layer 260 and the intermediate common electrode 241 and is electrically separated.

Similarly, in the scanning direction, (1) a plurality of protruding portions 245 protruding in the scanning direction from the second extending portion 244 from the left toward the end 240R, and the third extending portion 244 from the left to the end. Between the plurality of protrusions 245 protruding in the scanning direction toward 240L, (2) the plurality of protrusions 245 protruding in the scanning direction from the third extending portion 244 from the left toward the end 240R, and the left. Between the plurality of protrusions 245 protruding in the scanning direction from the fourth extending portion 244 to the end 240L, (3) the scanning direction from the fourth extending portion 244 from the left toward the end 240R. Between the plurality of protrusions 245 protruding from the left and the plurality of protrusions 245 protruding in the scanning direction from the fifth extending portion 244 from the left toward the end 240L, (4) the fifth extending portion from the left. Between the plurality of protrusions 245 protruding in the scanning direction from the portion 244 toward the end 240R and the plurality of protrusions 245 protruding in the scanning direction from the sixth extending portion 244 from the left toward the end 240L. , (5) A plurality of projecting portions 245 projecting from the extending portion 243 toward the end portion 240R in the scanning direction, and a plurality of projecting portions 245 protruding from the first extending portion 244 from the left toward the end portion 240L in the scanning direction. Two rows of conductor layer rows 270 are also arranged between the protrusions 245 and the protrusions 245. Further, a row of conductor layer rows 270 is provided between the plurality of protrusions 245 protruding in the scanning direction from the sixth extending portion 244 from the left toward the end 240R and the end 240R of the intermediate piezoelectric layer 240. Have been placed.

Each conductor layer 260 has a substantially square shape. As shown in FIG. 8A, the length of one side of each conductor layer 260 is substantially the same as the width of the narrow portion 143 in the transport direction, and shorter than the width of the narrow portion 143 in the scanning direction. .. Each conductor layer 260 is arranged adjacent to one of the protrusions 245 in the scanning direction. The position of each conductor layer 260 in the transport direction and the position of one of the protrusions 245 adjacent to each other in the scanning direction in the transport direction are substantially the same. It should be noted that each conductor layer 260 is arranged at a position where it does not overlap with the narrow portion 143 of the individual electrode 141 in the stacking direction. Further, each conductor layer 260 is arranged at a position where it overlaps with a plurality of through holes 360 described later in the stacking direction.

<Lower common electrode 341>
As shown in FIG. 4, a lower common electrode 341 is formed on the upper surface of the lower piezoelectric layer 340. As shown in FIG. 7, the lower common electrode 341 has an extending portion 342 extending in the scanning direction (left-right direction) so as to cover the end portion 340D in the transport direction of the lower piezoelectric layer 340, and the lower piezoelectric layer 340. An extending portion 343 extending in the transport direction so as to cover the end portion 340R in the scanning direction, and six extending in the transport direction from the extending portion 342 toward the end portion 340U in the transport direction of the lower piezoelectric layer 340. It has an extending portion 344 and a plurality of extending portions 345 protruding from each extending portion 344 on both sides in the scanning direction. Further, a plurality of projecting portions 345 also project from the extending portion 343 toward the end portion 340L in the scanning direction of the lower piezoelectric layer 340 in the scanning direction. The extending portion 342 is located at a position where it does not overlap with the pressure chamber 26 and the individual electrode 141 in the stacking direction. Further, in the stacking direction, the position does not overlap with the intermediate common electrode 241.

Each of the six extending portions 344 constitutes two individual electrode rows 150 adjacent to each other in the scanning direction so as not to overlap with the wide portion 142 of the individual electrode 141 constituting the individual electrode row 150 in the stacking direction. It extends in the transport direction between the wide portions 142 of 141. In FIG. 6, of the six extending portions 344, the first extending portion 244 from the left passes between the wide portions 142 constituting the first and second individual electrode rows 150 from the left in the scanning direction. It extends in the transport direction. The second extending portion 344 from the left side extends in the transport direction so as to pass between the wide portion 142 constituting the third and fourth individual electrode rows 150 from the left in the scanning direction. The third extending portion 244 from the left side extends in the transport direction so as to pass between the wide portions 142 constituting the fifth and sixth individual electrode rows 150 from the left in the scanning direction. The third extending portion 244 from the left side passes between the dummy electrode 171 constituting the dummy electrode row 170 and the wide portion 142 forming the seventh individual electrode row 150 from the left in the scanning direction. It is extended to. The fifth extending portion 344 from the left side extends in the transport direction so as to pass between the wide portion 142 constituting the eighth and ninth individual electrode rows 150 from the left in the scanning direction. The sixth extending portion 344 from the left side extends in the transport direction so as to pass between the wide portions 142 constituting the tenth and eleventh individual electrode rows 150 from the left in the scanning direction.

The fourth extending portion 344 from the left side is located at the boundary between the pressure chamber row 25 for color ink and the pressure chamber row 25 for black ink. The widths of the six extending portions 344 are the same. With respect to the five extending portions 344 excluding the fourth extending portion 344 from the left, the individual electrodes 141 constituting the two individual electrode rows 150 sandwiching each extending portion 344 in the scanning direction have a narrow portion 143 in the scanning direction. Are arranged to face each other (see FIG. 5). That is, with respect to the five extending portions 344 excluding the fourth extending portion 344 from the left, the scanning of the wide portion 142 of the individual electrodes 141 constituting the two individual electrode rows 150 sandwiching each extending portion 344 in the scanning direction. The magnitude of the interval in the direction is L1. Further, between the dummy electrode 171 constituting the dummy electrode row 170 and the wide portion 142 of the individual electrode 141 forming the seventh individual electrode row 150 from the left, sandwiching the fourth extending portion 344 from the left in the scanning direction. The magnitude of the interval in the scanning direction of is also L1. Along with this, the width of the six extending portions 344 in the scanning direction is also L1.

Next, the positional relationship between the pressure chamber 26, the individual electrodes 141, and the lower common electrode 341 will be described with reference to FIG. 8 (b). In FIG. 8 (b), four rows of individual electrodes arranged in the scanning direction are shown, but here, the individual electrodes included in the second row of individual electrodes from the left in FIG. 8 (b). The positional relationship between 141 and the pressure chamber 26 and the lower common electrode 341 that overlap each other in the stacking direction will be described as an example. In order to make the drawings easier to see, the lower common electrode 341 and the through hole 360 formed in the lower conductor layer 340 are shown by solid lines, and the pressure chamber 26, the individual electrodes 141, and the like are shown by dotted lines.

The length of the protruding portion 345 of the lower common electrode 341 in the scanning direction is substantially the same as the length of the wide portion 142 of the individual electrode 141 in the scanning direction.

The end portion 26L of the pressure chamber 26 is located between the end portion 344L and the end portion 344R of the extending portion 344 in the scanning direction in the scanning direction. The end portion 26R of the pressure chamber 26 is at substantially the same position in the scanning direction as the end portion 345R in the scanning direction of the protruding portion 345 of the lower common electrode 341. The end portion 344R of the extending portion 344 of the lower common electrode 341 is located between the end portion 26L of the pressure chamber 26a and the end portion 142L of the wide portion 142 of the individual electrode 141 in the scanning direction.

As described above, the end portion 142L of the wide portion 142 is at substantially the same position in the scanning direction as the end portion 245L of the protruding portion 245 of the intermediate common electrode 241 in the scanning direction (see FIG. 8A). Therefore, it can be seen that the protruding portion 245 of the intermediate common electrode 241 and the extending portion 344 of the lower common electrode 341 do not overlap in the stacking direction. Further, the end portion 244L of the extending portion 244 of the intermediate common electrode 241 is located at substantially the same position as the nozzle 23 in the scanning direction (see FIG. 8A). Therefore, it can be seen that the protruding portion 345 of the lower common electrode 341 and the extending portion 244 of the intermediate common electrode 241 overlap each other in the scanning direction.

The center position of the protrusion 345 of the lower common electrode 341 in the transport direction is substantially the same as the center position of the gap between the two pressure chambers 26 adjacent to each other in the transport direction in the transport direction. The length of the gap between the two pressure chambers 26 adjacent to each other in the transport direction in the transport direction is shorter than the length in the transport direction of the protrusion 345 of the lower common electrode 341. Therefore, both ends of the pressure chamber 26 in the transport direction overlap with the protruding portion 345 of the lower common electrode 341 in the stacking direction. The length of the overlapping portion of the pressure chamber 26 and the protruding portion 345 of the lower common electrode 341 in the stacking direction in the transport direction is shorter than 1/4 of the length in the transport direction of the pressure chamber 26. As described above, at both ends of the pressure chamber 26 in the transport direction, about 1/4 of the length of the pressure chamber 26 in the transport direction does not overlap with the protruding portion 245 of the intermediate common electrode 241 in the stacking direction. Therefore, the protruding portion 345 of the lower common electrode 341 and the protruding portion 245 of the intermediate common electrode 241 do not overlap in the stacking direction.

As described above, the central position of the pressure chamber 26 in the transport direction and the central position of the wide portion 142 of the individual electrode 141 in the transport direction are substantially the same in the transport direction, and the wide portion of the individual electrode 141 is provided. The length of 142 in the transport direction is longer than the length of the pressure chamber 26 in the transport direction. Therefore, both ends of the wide portion 142 in the transport direction overlap with the protruding portions 345 of the lower common electrode 341 in the stacking direction. The length of the overlapping portion in the stacking direction between the wide portion 142 and the protruding portion 345 of the lower common electrode 341 is the length of the overlapping portion in the stacking direction between the pressure chamber 26 and the protruding portion 345 of the lower common electrode 341. Longer than the length in the direction.

<Through hole 360>
As shown in FIG. 7, the six extending portions 344 are formed with two rows of through-hole rows 370 extending in the transport direction. The two rows of through holes 370 are aligned in the scanning direction. Each through hole row 370 is composed of a plurality of through holes 360 arranged at an arrangement pitch P in the transport direction. In the two rows of through hole rows 370, the positions of the through holes 360 in the transport direction are deviated by half (P / 2) of the arrangement pitch P of each through hole row 370.

Each through hole 360 has a substantially square shape in a plan view. As shown in FIG. 8B, the length of one side of each through hole 360 is substantially the same as the length of the narrow portion 143 in the transport direction, and shorter than the length of the narrow portion 143 in the scanning direction. .. Further, the length of one side of each through hole 360 is shorter than the width of each protrusion 345 in the transport direction. Each through hole 360 is arranged so as to be adjacent to one of the protrusions 345 in the scanning direction, and the position of each through hole 360 in the transport direction and the position of one of the protrusions 345 adjacent to each other in the scanning direction in the transport direction. The position is almost the same in the transport direction. Each through hole 360 is arranged at a position where it does not overlap with the narrow portion 143 of the individual electrode 141 in the stacking direction. Further, each through hole 360 is arranged at a position where it overlaps with the plurality of conductor layers 260 in the stacking direction.

As shown in FIG. 8B, the distance between each through hole 360 and the narrow portion 143 of the individual electrode 141 adjacent to the through hole 360 in the scanning direction in the scanning direction is the distance between each through hole 360 and the carrier. It is smaller than the distance between the through hole 360 in the direction and the narrow portion 143 of the adjacent individual electrode 141 in the transport direction.

<Wiring member 50>
As shown in FIG. 2, the wiring member 50 includes a flexible wiring board 51 (FPC51) and a driver IC 52 arranged on the FPC51. The contacts (not shown) formed on the flexible wiring board 51 are electrically connected to the bumps (not shown) provided in the narrow portion 143 of each individual electrode 141, and are individually connected to each individual electrode 141. The potential can be set. Further, as described above, the driver IC 52 can set a predetermined constant potential with respect to the intermediate common electrode 241 and the lower common electrode 341.

<Drive of Piezoelectric Element 401>
As described above, the piezoelectric body 40 is a plate-shaped member having a substantially rectangular shape in a plan view, which is arranged on the diaphragm 30 so as to cover the plurality of pressure chambers 26 (see, for example, FIG. 2). The piezoelectric body 40 is formed with a plurality of piezoelectric elements 401 provided corresponding to the plurality of pressure chambers 26, respectively. Hereinafter, the driving of the piezoelectric element 401 will be described. The portion of the upper piezoelectric layer 140 sandwiched between the individual electrodes 141 and the intermediate common electrode 241 in the stacking direction (hereinafter referred to as the first active portion 41 (see FIGS. 4A and 4B)) is located in the stacking direction. It is polarized. Further, a portion of the upper piezoelectric layer 140 and the intermediate piezoelectric layer 240 sandwiched between the individual electrodes 141 and the lower common electrode 341 in the stacking direction (hereinafter referred to as the second active portion 42 (see FIGS. 4A and 4B). )) Is also polarized in the stacking direction. Here, while the driver IC 51 is energized, a predetermined first potential (for example, 24V) is always applied to the intermediate common electrode 241 and a predetermined second potential (for example, 0V) is always applied to the lower common electrode 341. It has been applied. Further, a first potential and a second potential are selectively applied to each individual electrode 141. Specifically, when the ink is not ejected from the pressure chamber 26 corresponding to the individual electrode 141, the individual electrode 141 is provided with the second potential. At this time, since no potential difference is generated between the individual electrode 141 and the lower common electrode 341, the second active portion 42 is not deformed. However, a potential difference between the first potential and the second potential (here, 24 V) is generated between the individual electrode 141 and the intermediate common electrode 241. As a result, the first active portion 41 is deformed so as to be convex downward (pressure chamber 26 side).

When the ink is ejected from the pressure chamber 26 corresponding to the individual electrode 141, the individual electrode 141 is applied with the first potential and then returned to the second potential. That is, a pulsed voltage signal that rises from the second potential to the first potential and returns to the second potential after a lapse of a predetermined time is applied to the individual electrodes 141. When the first potential is applied to the individual electrode 141, the potential difference between the individual electrode 141 and the intermediate common electrode 241 disappears, so that the first potential is deformed so as to be convex to the lower side (pressure chamber 26 side). The active part 41 tries to return to its original state. At this time, the first active portion 41 is displaced upward, which increases the volume of the pressure chamber 26. At this time, a potential difference (24V in this case) is generated between the individual electrode 141 and the lower common electrode 341, and the second active portion 42 is deformed so as to lift the central portion of the pressure chamber 26 upward, so that the pressure chamber 26 is deformed. The increase in volume can be increased. Next, when the potential of the individual electrode 141 returns to the second potential, as described above, there is no potential difference between the individual electrode 141 and the lower common electrode 341, so that the second active portion 42 returns to its original state. , A potential difference between the first potential and the second potential (here, 24 V) is generated again between the individual electrode 141 and the intermediate common electrode 241. As a result, the first active portion 41 is deformed so as to be convex downward (pressure chamber 26 side). At this time, the pressure applied to the pressure chamber 26 causes the ink in the pressure chamber 26 to be ejected from the nozzle 23.

<About the swell of the piezoelectric layer>
As shown in FIGS. 11A and 11B, the conductor layer 260 is not formed on the upper surface of the intermediate piezoelectric layer 240, and the extending portion 344 of the lower common electrode 341 formed on the lower piezoelectric layer 340. Consider the case where the through hole 360 is not formed in. At this time, as shown in FIG. 11A, the intermediate common electrode 241 is formed on the surface of the intermediate piezoelectric layer 240 so as to have an extending portion 244 and a protruding portion 245 as described above. Therefore, it can be seen that on the surface of the intermediate electrode layer 240, a portion where the intermediate common electrode 241 is sparse and a portion where the intermediate common electrode 241 is dense are arranged so as to be arranged in the scanning direction. The portion of the surface of the intermediate electrode layer 240 where the extending portion 244 and the protruding portion 245 are formed corresponds to the portion where the intermediate common electrode 241 is dense, and the portion where the extending portion 244 and the protruding portion 245 are not formed. Corresponds to the portion where the intermediate common electrode 241 is sparse.

Further, as shown in FIG. 11B, the lower common electrode 341 is formed on the upper surface of the lower piezoelectric layer 340 so as to have an extending portion 344 and a protruding portion 345 as described above. Then, it can be seen that on the surface of the lower electrode layer 340, a portion where the lower common electrode 341 is sparse and a portion where the lower common electrode 341 is dense are arranged so as to be lined up in the scanning direction. The portion of the surface of the lower electrode layer 340 where the extending portion 344 and the protruding portion 345 are formed corresponds to the portion where the lower common electrode 341 is densely formed, and the portion where the extending portion 344 and the protruding portion 345 are not formed. Corresponds to the portion where the lower common electrode 341 is sparse.

Here, in general, when a metal thin film layer such as an individual electrode, an intermediate common electrode, and a lower common electrode is formed on the surface of the piezoelectric layer, the metal thin film layer is formed by printing or the like on a sheet of the piezoelectric material. It is firing. As shown in FIG. 11 (c), thermal stress in the compression direction remains in the fired piezoelectric layer. As described above, when a sparse part and a dense part of the metal thin film layer are formed on the surface of the piezoelectric layer, the magnitude of the residual thermal stress differs between them, so that the fired piezoelectric is fired. Wavy deformation (swell) occurs in the layer. In particular, as described above, when the sparse portion and the dense portion of the metal thin film layer are lined up in a predetermined direction, it is considered that the swell of the piezoelectric layer appears remarkably in the predetermined direction. Further, it is considered that the swell of the piezoelectric layer appears remarkably even when the difference in area between the sparse portion and the dense portion of the metal thin film layer is large in a predetermined direction.

Therefore, in the present embodiment, by forming through holes in the dense portion of the metal thin film layer formed on the surface of the piezoelectric layer, the area of the portion where the metal thin film layer is sparse and the dense portion in a predetermined direction is formed. The difference between the two is small. As a result, the swell generated in the piezoelectric layer is reduced.

As described above, the width of the extending portion 244 of the intermediate common electrode 241 formed on the surface of the intermediate piezoelectric layer 240 in the scanning direction is L2, whereas the width formed on the surface of the lower electrode layer 340 is formed. The width of the extending portion 344 of the lower common electrode 341 in the scanning direction is L1 (L1> L2). That is, when comparing the ratio of the portion where the electrode (metal thin film) is densely formed and the portion where the electrode (metal thin film) is sparsely formed in the intermediate piezoelectric layer 240 and the lower piezoelectric layer 340, the lower piezoelectric layer 340 is the intermediate piezoelectric layer. Compared with 240, the area of the portion where the electrodes are densely formed is large, and conversely, the area of the portion where the electrodes are sparsely formed is small.

In the above embodiment, in the lower piezoelectric layer 340 in which the area of the portion where the electrodes are densely formed is large, a plurality of through holes 360 are formed in the extending portion 344 of the lower common electrode 341. Therefore, the through hole 360 can be easily formed, and the area of the portion where the electrodes are densely formed can be reduced. As a result, the swell generated in the lower piezoelectric layer 340 can be reduced. In this embodiment, the extending portion 244 of the intermediate common electrode 241 is not provided with a through hole.

In the above embodiment, the plurality of through holes 360 are arranged at positions that do not overlap with the narrow portion 143 of the individual electrode 141 in the stacking direction. Bumps (not shown) are formed in the narrow portion 143 of the individual electrode 141, and are connected to the contacts of the FPC 51 as described above. At that time, a force is applied in the stacking direction, but in the present embodiment, the through hole 360 is not formed in the portion overlapping the narrow portion 143 in the stacking direction. Therefore, the force applied when the contact point of the FPC 51 is connected to the bump of the narrow portion 143 can be received by the extending portion 344 of the lower common electrode 341. Therefore, the reliability when connecting the contact of the FPC 51 and the bump of the narrow portion 143 can be improved.

In the above embodiment, the plurality of through holes 360 are formed at positions overlapping with the conductor layer 260 in the stacking direction. The formation of a plurality of through holes 360 in the extending portion 342 of the lower common electrode 341 inevitably reduces the mechanical strength of the piezoelectric body 40, but it overlaps with the plurality of through holes 360 in the stacking direction. By forming the plurality of conductor layers 260 at the positions, it is possible to reduce such a decrease in the mechanical strength of the piezoelectric body 40.

As shown in FIG. 11C, the neutral surface of the piezoelectric body 40 is located inside the intermediate piezoelectric layer 240 in the stacking direction. An intermediate common electrode 241 and an individual electrode 141 are arranged on the upper side of the neutral surface, and a lower common electrode 341 is arranged on the lower side of the neutral surface. It is known that when the area of the metal thin film layer such as an electrode is significantly different between the upper side and the lower side of the neutral surface, the piezoelectric body is greatly warped due to this. For example, if the area of the lower common electrode on the lower side of the neutral surface is too large, the piezoelectric body may be largely along so as to be convex upward due to this. In such a case, the area of the lower common electrode 341 can be reduced by forming the through hole 390 in the extending portion 344 of the lower common electrode 341 as in the present embodiment. Warpage can also be reduced.

When the distance in the stacking direction between the neutral surface and the lower common electrode 341 is larger than the distance in the stacking direction between the neutral surface of the piezoelectric body 40 and the intermediate common electrode 241, the intermediate common electrode Rather than providing a through hole in the extending portion 244 of 241, providing a through hole in the extending portion 344 of the lower common electrode 341 can further reduce the large warp as described above.

It is also possible to adjust the length of the protruding portion 345 of the lower common electrode 341 in the scanning direction so as not to overlap the extending portion 244 of the intermediate common electrode 241 in the stacking direction. When the protruding portion 345 of the lower common electrode 341 and the intermediate common electrode 241 overlap in the stacking direction, the protruding portion 345 of the lower common electrode 341 and the intermediate common electrode 241 overlap with each other when the driver IC 52 is energized. A voltage is always applied to the portion where the voltage is applied. Therefore, it is preferable that the length of the protruding portion 345 of the lower common electrode 341 in the scanning direction is set so as not to greatly overlap with the extending portion 244 of the intermediate common electrode 241 in the stacking direction. However, the present invention does not necessarily have to be in such an embodiment so that the length of the protruding portion 345 of the lower common electrode 341 in the scanning direction does not overlap with the extending portion 244 of the intermediate common electrode 241 in the stacking direction at all. It can also be set. The length of the protruding portion 345 of the lower common electrode 341 in the scanning direction can be set so as not to penetrate the extending portion 244 of the intermediate common electrode 241 in the scanning direction when viewed from the stacking direction.

<Change form>
In the above embodiment, a plurality of through holes 360 are formed in the extending portion 344 of the lower common electrode 341, but the number, shape, and position of the plurality of through holes 360 are not limited to the example of the above embodiment. .. For example, the plurality of through holes 360 have a substantially square shape when viewed from the stacking direction, but the shape is not limited to this, and any shape can be used. Further, the plurality of through holes 360 were formed at positions that did not overlap with the narrow portion 143 of the individual electrode 141 in the stacking direction, but a part or all of the through holes 360 were formed with the narrow portion 143 of the individual electrode 141. It may be formed at overlapping positions.

For example, as shown in FIG. 9, a plurality of through holes 360A may be formed at positions overlapping with the narrow portion 143 of the individual electrode 141 in the stacking direction. The through hole 360A shown in FIG. 9 has a substantially rectangular shape that is long in the scanning direction. Since the through hole 360A overlaps the narrow portion 143 of the individual electrode 141 in the stacking direction, a force applied in the stacking direction when connecting the contact point of the FPC 51 and the bump (not shown) provided in the narrow portion 143 is applied. It cannot be received by the extending portion 344 of the lower common electrode 341. However, since the area of the through hole 390A can be increased as compared with the through hole 390 of the above embodiment, the area of the portion of the lower piezoelectric layer 340 in which the electrodes are densely formed can be reduced. As a result, the swell generated in the lower piezoelectric layer 340 can be reduced.

In the above embodiment, the plurality of through holes 360 may be formed in the extending portion 344 of the lower common electrode 341, but the present invention is not necessarily limited to such an embodiment. A plurality of through holes may be formed in the extending portion 244 of the intermediate common electrode 241 in place of the lower common electrode 341 or in addition to the lower common electrode 341.

In the above embodiment, a plurality of conductor layers 260 are formed on the intermediate piezoelectric layer 240. The shape, size, and position of the conductor layer 260 are not limited to the example of the above embodiment, and can be arbitrarily adjusted. Alternatively, the conductor layer 260 may not be provided on the intermediate piezoelectric layer 240.

In the above embodiment, the piezoelectric body 40 has three piezoelectric layers, and an electrode is formed on the upper surface of each piezoelectric layer. However, this teaching is not limited to such an aspect. The piezoelectric body may have two or three or more piezoelectric layers, and an electrode may be formed on the lower surface of each piezoelectric layer. In the above embodiment, the piezoelectric body has two common electrodes (intermediate common electrode and lower common electrode), but the present teaching is not limited to such an embodiment and has only one common electrode. May be good. Further, the shape of the common electrode (the shape of the extending portion and the protruding portion) can be arbitrarily adjusted as needed. Further, in the above embodiment, the individual electrodes are formed on the uppermost side in the stacking direction, and the common electrodes (intermediate common electrode and lower common electrode) are provided below the individual electrodes. It is not limited to such an aspect. For example, an individual electrode may be formed on the lowermost side in the stacking direction, and a common electrode may be provided on the upper side thereof. In the above embodiment, the individual electrode 141 has a wide portion 142 and a narrow portion 143, but the shape of the individual electrode is not necessarily limited to such an embodiment. For example, the width of the individual electrodes in the transport direction may be uniform in the scanning direction.

In the above embodiment, a plurality of through holes 360 are formed, but this teaching is not limited to such an embodiment. For example, as shown in FIG. 10, one through hole 360B may be formed in each extending portion 344 of the lower common electrode 341. The through hole 360B is located at the center of each extending portion 344 in the scanning direction with respect to the scanning direction. Further, the through hole 360B extends over almost the entire area of each extending portion 344 in the conveying direction so as to be adjacent to almost all the protruding portions 345 in the conveying direction in the conveying direction. The width of the through hole 360B in the scanning direction is approximately twice the length of one side of the through hole 360 in the above embodiment.

As described above, by forming one through hole 360B in each extending portion 344 of the lower common electrode 341, the lower common electrode 341 is compared with the case where a plurality of through holes 360 as in the above embodiment are formed. The area of the portion where the electrodes are densely formed can be reduced. As a result, the swell generated in the lower piezoelectric layer 340 can be further reduced. It should be noted that the shape and size of the through holes 360, 360A and 360B are examples, and it goes without saying that any shape and size can be used as long as the through holes 360, 360A and 360B are formed in each extending portion 344. stomach. For example, one through hole 360B may be formed in a part of the extending portion 344 of the lower common electrode 341, and a plurality of through holes 360, 360A may be provided in the remaining extending portion 344. Alternatively, through holes 360, 360A and 360B can be mixed in one extending portion 344.

In the embodiments and modifications described above, the present teaching is applied to an inkjet head 5 that ejects ink onto recording paper to print an image or the like. In the above embodiment, the inkjet head 5 is a so-called serial type inkjet head, but the present teaching is not limited to this, and can be applied to a so-called line type inkjet head. Further, this teaching is not limited to the inkjet head that ejects ink. This teaching can also be applied to liquid discharge devices used for various purposes other than printing images and the like. For example, it is possible to apply this teaching to a liquid discharge device that discharges a conductive liquid onto a substrate to form a conductive pattern on the surface of the substrate.

5 Inkjet head 40 Piezoelectric body 140 Upper piezoelectric layer 141 Individual electrode 240 Intermediate piezoelectric layer 241 Intermediate common electrode 340 Lower piezoelectric layer 341 Lower common electrode 360, 360A Through hole

Claims (17)

A piezoelectric body in which a plurality of piezoelectric layers are laminated, and the first end and the second end separated in the first direction orthogonal to the stacking direction of the plurality of piezoelectric layers.
A plurality of individual electrodes formed along the first surface, which is a surface orthogonal to the stacking direction, and
A piezoelectric body comprising a first common electrode formed along a second surface that is orthogonal to the stacking direction and whose position in the stacking direction is different from the position of the first surface in the stacking direction. ,
The plurality of individual electrodes constitute a plurality of individual electrode rows arranged with a gap between the first end and the second end.
The plurality of individual electrode rows have a first individual electrode row and a second individual electrode row adjacent to the first individual electrode row in the first direction, and the first individual electrode row has the first direction. Located between the first end and the second individual electrode row in
The plurality of individual electrodes constituting the first individual electrode row are arranged in a direction orthogonal to the stacking direction and along a second direction intersecting with the first direction.
The first common electrode includes a first extending portion extending along the second direction so as to pass a position between the first individual electrode row and the second individual electrode row in the first direction, and the above-mentioned first common electrode. A plurality of first projecting portions projecting from the first extending portion toward the first end are provided.
Each first protrusion partially overlaps with one of the plurality of individual electrodes constituting the first individual electrode row in the stacking direction.
A liquid discharge head characterized in that a plurality of through holes are formed in the first extending portion. A surface orthogonal to the stacking direction and provided with a second common electrode formed along a third surface whose position in the stacking direction is different from the first surface and the second surface.
The plurality of individual electrode rows are a third individual electrode row adjacent to the first individual electrode row in the first direction, and are between the first end and the first individual electrode row in the first direction. It has a third individual electrode row located and
The second common electrode includes a second extending portion extending along the second direction so as to pass through a position between the first individual electrode row and the third individual electrode row in the first direction. A plurality of second projecting portions projecting from the second extending portion toward the second end are provided.
The liquid discharge head according to claim 1, wherein each second protruding portion partially overlaps with one of the plurality of individual electrodes constituting the first individual electrode row in the stacking direction. The liquid discharge head according to claim 2, wherein the width of the first extending portion in the first direction is larger than the width of the second extending portion in the first direction. The liquid discharge head according to claim 3, wherein a through hole is not formed in the second extending portion. The distance in the stacking direction from the neutral surface of the piezoelectric body to the second surface is larger than the distance in the stacking direction from the neutral surface to the third surface.
The liquid discharge head according to claim 2, wherein the width of the first extending portion in the first direction is larger than the width of the second extending portion in the first direction. In the stacking direction, the neutral surface of the piezoelectric body is located between the first surface and the third surface and the second surface.
The liquid discharge head according to any one of claims 2 to 5, wherein the area of the first common electrode is larger than the area of the second common electrode. Each individual electrode has a first portion and a second portion arranged in the first direction.
The second portion of each of the individual electrodes overlaps with the first extending portion in the stacking direction.
Claims 1 to 1, wherein the plurality of through holes formed in the first extending portion are arranged so as not to overlap with the second portion of the plurality of individual electrodes in the stacking direction. 6. The liquid discharge head according to any one of 6. The liquid discharge head according to claim 7, wherein the length of the second portion of each of the individual electrodes in the second direction is smaller than the length of the first portion in the second direction. The claim is characterized in that each through hole is arranged at a position where two second portions of two adjacent individual electrodes adjacent to each other in the second direction overlap with a gap in the second direction in the stacking direction. 8. The liquid discharge head according to 8. The first common electrode includes a plurality of third protrusions protruding from the first extension toward the second end.
Each third protrusion partially overlaps with one of the plurality of individual electrodes constituting the second individual electrode row in the stacking direction.
Each through hole is
The first position of the plurality of individual electrodes constituting the first individual electrode row, which overlaps with the gap in the second direction of the two second ends of the two individual electrodes adjacent to each other in the second direction. When,
The second position of the plurality of individual electrodes constituting the second individual electrode row, which overlaps with the gap in the second direction of the two second ends of the two individual electrodes adjacent to each other in the second direction. The liquid discharge head according to claim 9, which is arranged in and. The distance between one of the plurality of through holes and the second portion of the individual electrode closest in the second direction in the second direction is the distance between one of the through holes and the individual closest in the first direction. The liquid discharge head according to claim 10, wherein the distance from the second portion of the electrode is larger than the distance in the first direction. The length of each through hole in the second direction is larger than the length of the second portion in the second direction.
The liquid discharge head according to any one of claims 8 to 10, wherein the length of each through hole in the first direction is smaller than the length of the second portion in the first direction. A piezoelectric body in which a plurality of piezoelectric layers are laminated, and the first end and the second end separated in the first direction orthogonal to the stacking direction of the plurality of piezoelectric layers.
A plurality of individual electrodes formed along the first surface, which is a surface orthogonal to the stacking direction, and
A piezoelectric body comprising a first common electrode formed along a second surface that is orthogonal to the stacking direction and whose position in the stacking direction is different from the position of the first surface in the stacking direction. ,
The plurality of individual electrodes constitute a plurality of individual electrode rows arranged with a gap between the first end and the second end.
The plurality of individual electrode rows have a first individual electrode row and a second individual electrode row adjacent to the first individual electrode row in the first direction, and the first individual electrode row has the first direction. Located between the first end and the second individual electrode row in
The plurality of individual electrodes constituting the first individual electrode row are arranged in a direction orthogonal to the stacking direction and along a second direction intersecting with the first direction.
The first common electrode includes a first extending portion extending along the second direction so as to pass a position between the first individual electrode row and the second individual electrode row in the first direction, and the above-mentioned first common electrode. A plurality of first projecting portions projecting from the first extending portion toward the first end are provided.
Each first protrusion partially overlaps with one of the plurality of individual electrodes constituting the first individual electrode row in the stacking direction.
A liquid discharge head characterized in that one through hole is formed in the first extending portion. The liquid according to claim 13, wherein the one through hole formed in the first extending portion extends in the second direction so as to be adjacent to the plurality of first protruding portions in the first direction. Discharge head. Each individual electrode has a first portion and a second portion arranged in the first direction.
The second portion of each of the individual electrodes overlaps with the first extending portion in the stacking direction.
The claim is characterized in that the one through hole formed in the first extending portion is arranged so as to partially overlap with the second portion of the plurality of individual electrodes in the stacking direction. Item 14. The liquid discharge head. A plurality of pressure chambers arranged so as to overlap the plurality of individual electrodes in the stacking direction, a plurality of nozzles corresponding to the plurality of pressure chambers, and the corresponding plurality of pressure chambers and the plurality of nozzles, respectively. The liquid discharge head according to any one of claims 1 to 15, further comprising a flow path unit in which a plurality of flow paths to be communicated are formed. The plurality of pressure chambers are arranged so as to form a first pressure chamber row that overlaps with the first individual electrode row in the stacking direction and a second pressure chamber row that overlaps with the second individual electrode row in the stacking direction. ,
The liquid discharge head according to claim 16, wherein the first extending portion of the first common electrode does not overlap with the first pressure chamber row and the second pressure chamber row in the stacking direction.

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