JP4221615B2 - Inkjet printer head and piezoelectric actuator - Google Patents

Description

  The present invention relates to an ink jet printer head, more specifically, an ink jet printer head in which a piezoelectric actuator is joined to a cavity unit having a plurality of pressure chambers, and a piezoelectric actuator.

  In the on-demand type ink jet printer head of the prior art, as disclosed in Patent Document 1 and Patent Document 2, etc., a plurality of plates are stacked to form a cavity unit having an ink flow path. The plate is a manifold as a nozzle plate having a plurality of nozzles, a base plate having a pressure chamber for each nozzle, and a common ink chamber connected to the ink supply source and connected to each pressure chamber. It is comprised from the manifold plate etc. which have a chamber. The piezoelectric actuator is configured by alternately stacking common electrodes and individual electrodes with a piezoelectric ceramic plate interposed therebetween, and an active portion that is an overlapping portion of the individual electrodes and the common electrode is seen in a plan view above the pressure chamber. The piezoelectric actuator and the cavity unit are joined so as to overlap.

  In order to apply a voltage to each active part of the piezoelectric actuator, a plurality of surface electrodes electrically connected to the individual electrode and the common electrode are provided on the upper surface of the piezoelectric actuator to transmit a control signal from the outside. The joining terminal portion of the cable member such as the flat cable is joined to the surface electrode with solder or the like.

In that case, in the configuration described in Patent Document 1 and Patent Document 2, the surface electrode corresponding to the individual electrode is located above the end portion of the individual electrode extending in the direction extending outward from the pressure chamber. That is, the plurality of surface electrodes are arranged in parallel with the same row adjacent to the outside of the row formed by the plurality of pressure chambers. The surface electrode corresponding to the common electrode is located at the end of the column.
JP 2001-246744 A Japanese Patent Laid-Open No. 2002-19102

  Since the end of the individual electrode extends in a direction extending outward from the pressure chamber, the longitudinal length of each pressure chamber of the piezoelectric actuator must be formed long for the arrangement of the surface electrode. There is a problem that both the piezoelectric actuator and the cavity unit cannot be made compact.

  In order to solve this problem, it is conceivable to shorten the end portion of the individual electrode extended outward from the pressure chamber. However, in this case, not only the size of the active portion is limited, but also the individual electrode and the surface electrode The conductive material that conducts the current is close to the active part and restricts the movement of the active part.

  An object of the present invention is to form an ink jet printer head and a piezoelectric actuator in a compact manner while solving the conventional problems.

In order to achieve the above object, an ink jet printer head according to a first aspect of the present invention includes a plurality of nozzles that eject ink and a plurality of pressure chambers that communicate with the nozzles and are arranged at predetermined intervals. In the inkjet printer head, wherein a piezoelectric actuator having an active portion that can be selectively driven for each pressure chamber is joined to the cavity unit, and ink in the pressure chamber is ejected from the nozzles by driving the active portion. The piezoelectric actuator includes a plurality of stacked sheets including piezoelectric sheets, a plurality of individual electrodes positioned corresponding to the plurality of pressure chambers and forming a column corresponding to the column of the pressure chambers, and the individual electrodes A common electrode sandwiching the piezoelectric sheet in the stacking direction and having the piezoelectric sheet as the active portion, and the upper surface of the uppermost sheet And a plurality of individual for surface electrodes connected via the individual electrodes and the internal connection electrodes, each individual electrode, an end portion connected to the internal connection electrode, and the pressure chamber from the portions corresponding to the pressure chamber It extends in the row direction so as to be located between adjacent pressure chambers .

  According to a second aspect of the present invention, in the inkjet printer head according to the first aspect, the pressure chambers are provided in a plurality of rows, the individual electrodes are provided in a plurality of rows correspondingly, and the plurality of rows of the individual electrodes are included. The two adjacent rows extend the opposite ends of the individual electrodes in the row direction and toward the other rows.

  According to a third aspect of the present invention, in the ink jet printer head according to the first or second aspect, a plurality of the piezoelectric sheets are provided, and the individual electrodes sandwiching the piezoelectric sheets with the common electrodes are plurally arranged in the stacking direction. The individual electrodes in the stacking direction have the end portions extended in the same direction.

  Furthermore, the invention according to claim 4 is the ink jet printer head according to any one of claims 1 to 3, wherein the internal connection electrode includes the individual electrode and the individual surface electrode among the plurality of sheets. An internal conduction electrode filled in a through hole penetrating the sheet between the two.

  According to a fifth aspect of the present invention, in the inkjet printer head according to the fourth aspect, the piezoelectric sheet includes a plurality of the piezoelectric sheets, the plurality of the individual electrodes sandwiching the piezoelectric sheets together with the common electrodes are provided in the stacking direction. A dummy electrode corresponding to the end is provided in the same plane as the common electrode between the electrode and the individual surface electrode, and the end and the dummy electrode are connected via the internal conductive electrode .

According to a sixth aspect of the present invention, in the inkjet printer head according to the fifth aspect, the internal conductive electrodes of the sheets adjacent to each other in the stacking direction are located at a distance so as not to overlap vertically in a plan view. .
The invention according to claim 7 relates to a piezoelectric actuator, wherein a plurality of sheets including a piezoelectric sheet are laminated, a plurality of individual electrodes arranged in rows in the surface direction of the sheet at a predetermined interval, and the individual electrodes A common electrode having the piezoelectric sheet sandwiched in the stacking direction as the active portion, and a plurality of individual surface electrodes located on the upper surface of the uppermost sheet and connected to the individual electrodes via internal connection electrodes Each of the individual electrodes extends in the column direction so that an end connected to the internal connection electrode is positioned between a portion forming the active portion and the individual electrode adjacent to the individual electrode. ing.
According to an eighth aspect of the present invention, in the piezoelectric actuator according to the seventh aspect, the individual electrodes are provided in a plurality of rows, and two adjacent rows among the plurality of rows of the individual electrodes are opposite sides of the individual electrodes. Are extended in the row direction toward the other row.
The invention according to claim 9 is the piezoelectric actuator according to claim 7 or 8, comprising a plurality of the piezoelectric sheets, and a plurality of the individual electrodes sandwiching the piezoelectric sheets together with the common electrodes in the stacking direction, Each individual electrode in the stacking direction extends the end in the same direction.
A tenth aspect of the present invention is the piezoelectric actuator according to any one of the seventh to ninth aspects, wherein the internal connection electrode is between the individual electrode and the individual surface electrode among the plurality of sheets. An internal conduction electrode filled in a through hole penetrating the sheet is included.
The invention according to claim 11 is the piezoelectric actuator according to claim 10, comprising a plurality of the piezoelectric sheets, a plurality of the individual electrodes sandwiching the piezoelectric sheets together with the common electrodes, in the stacking direction, and the individual electrodes. A dummy electrode corresponding to the end portion is provided in the same plane as the common electrode between the individual surface electrode and the individual surface electrode, and the end portion and the dummy electrode are connected via the internal conductive electrode.
According to a twelfth aspect of the present invention, in the piezoelectric actuator according to the eleventh aspect, the internal conductive electrodes of the sheets adjacent to each other in the stacking direction are located at a distance so as not to overlap each other in plan view.

The ink jet printer head according to claim 1, wherein an end of each individual electrode connected to the internal connection electrode is arranged in a row direction so as to be positioned between a portion corresponding to the pressure chamber and a pressure chamber adjacent to the pressure chamber. Since the end of the individual electrode does not extend in the direction extending outward from the pressure chamber as in the prior art, the length in the longitudinal direction of each pressure chamber of the piezoelectric actuator should be shortened. The inkjet printer head can be made compact. In addition, it is possible to eliminate the limitation of the size of the active portion or the movement of the active portion as in the conventional case.

The piezoelectric actuator according to claim 7 is arranged such that an end portion of each individual electrode connected to the internal connection electrode is positioned between a portion forming the active portion and the individual electrode adjacent thereto. Since it extends in the direction, the end of the individual electrode does not extend in the outward extending direction as in the prior art, so that the piezoelectric actuator can be made compact. In addition, it is possible to eliminate the limitation of the size of the active portion or the movement of the active portion as in the conventional case.

  According to the second and eighth aspects of the present invention, two adjacent rows among the plurality of rows of the individual electrodes extend the ends of the individual electrodes facing each other in the row direction toward the other rows. Therefore, even if there are a plurality of individual electrodes, it can be made compact.

  Further, the invention described in claims 3 and 9 includes a plurality of piezoelectric sheets, a plurality of individual electrodes sandwiching the piezoelectric sheets together with the common electrodes in the stacking direction, and the end portions of the individual electrodes in the stacking direction are the same. Since it extends in the direction, the ends of the plurality of individual electrodes can be easily connected via the internal connection electrodes.

  Further, according to the invention described in claims 4 and 10, the individual electrode and the individual surface electrode can be connected by the internal conduction electrode filled in the through hole penetrating the sheet therebetween.

  The invention described in claims 5 and 11 is an interior in which an individual electrode and an individual surface electrode are filled in a through hole penetrating a sheet between them through a dummy electrode on the same plane as the common electrode. It can be connected by a conductive electrode.

  According to the sixth and twelfth aspects of the present invention, the individual electrode and the individual surface electrode can be connected by the internal conduction electrode that is positioned at a distance so as not to overlap vertically in plan view.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a cavity unit 11 and a piezoelectric actuator 12 in a piezoelectric inkjet printer head 10 according to an embodiment of the present invention. FIG. 2 is a third spacer plate 21 adjacent to the cavity plate and its lower surface side. FIG. 3 is an enlarged perspective view taken along the line III-III in FIG. 1, FIG. 4 is an enlarged sectional view taken along the line IV-IV in FIG. 1, and FIGS. The figure which shows the electrode pattern of each layer in the piezoelectric actuator 12, and FIGS. 13-15 are top views which show the overlapping state of an electrode pattern. In FIG. 1, the plate laminated piezoelectric actuator 12 joined to the upper surface of the cavity unit 11 made of a metal plate has flexibility as an example of a cable member for connection to an external device. The flat cable 13 (individually indicated by reference numerals 13a and 13b, see FIGS. 1, 3 and 4A) is lap-joined with an adhesive.

  The cavity unit 11 is configured as shown in FIGS. That is, a total of 9 base plates 22 in which the nozzle plate 14, the cover plate 15, the damper plate 16, the two manifold plates 17, 18, the three spacer plates 19, 20, 21 and the pressure chamber 23 are formed in order from the lower layer. In this embodiment, each of the plates 15 to 22 is made of 42% nickel alloy steel plate and has a thickness of 50 μm, except for the nozzle plate 14 made of synthetic resin. It has a thickness of about ~ 150 μm.

  The nozzle plate 14 has a large number of nozzles 24 for ejecting ink having a small diameter (in the embodiment, about 25 μm) in the first direction (the long side direction of the cavity unit 11) in FIG. In FIG. 3, four rows formed along the X-axis direction) are provided in a four-row staggered arrangement.

  That is, the cavity unit 11 is cut along the Y-axis direction (short side direction) in FIG. 1, and only the right side of the center line C of the short side is shown in FIG. 24-1 and the second row of nozzles 24-2 closer to the center line C are connected to two parallel adjacent reference lines (not shown) of the nozzle plate 14 extending in the first direction. A large number of holes are formed in a staggered arrangement at intervals of a minute pitch P along the same line. Similarly, on the left side of the center line C, the third row of nozzles 24-3 and the fourth row of nozzles 24- 4 (not shown in FIGS. 3 and 4A) is a staggered pattern at intervals of a minute pitch P along two parallel adjacent reference lines extending in the first direction. A large number of holes are drilled in an array. Further, the set of the first row nozzle 24-1 and the second row nozzle 24-2 and the set of the third row nozzle 24-3 and the fourth row nozzle 24-4 are the same as those of the cavity unit 11. They are arranged in parallel in the short-side direction (second direction, Y-axis direction in FIG. 1) at intervals. In the embodiment, the length of each nozzle row of the first row to the fourth row is 2 inches, and the number of each nozzle 24 is 150, that is, the arrangement density is 75 (dpi [dot per inch]). is there.

  In the base plate 22 which is the uppermost layer of the cavity unit 11 shown in FIG. 2, pressure chambers 23 are provided so as to penetrate the plate thickness direction with the same pitch P corresponding to the nozzles 24. The pressure chambers 23 are arranged in a row in the long side direction (X-axis direction) of the cavity unit 11. Therefore, the adjacent pressure chambers 23 are isolated by the elongated partition wall 70 that is substantially parallel to the short side of the cavity unit 11 (see FIGS. 2, 3, and 13). The width dimension W2 of each partition wall 70 is set slightly smaller than the width dimension 1 of the pressure chamber 23 (see FIGS. 2 and 13).

  The first row of pressure chambers 23-1 corresponds to the first row of nozzles 24-1. Similarly, the second row of pressure chambers 23-2 is the second row of nozzles 24-2, and the third row of pressure chambers 23-3 is the third row of nozzles 24-3, and the fourth row of pressure chambers. 23-4 has a corresponding relationship with the nozzle 24-4 in the fourth row.

  Next, two piezoelectric elements are arranged such that the arrangement relationship of the pressure chambers 23 in the base plate 22 which is the uppermost layer of the cavity unit 11 is arranged in the column direction (first direction, X-axis direction) of the nozzles 24 thereon. This will be described from the relationship with the arrangement of the active portion in the actuator 12 (indicated by reference numerals 12a and 12b individually).

  One piezoelectric actuator 12a (or 12b) has 75 active portions so as to actuate half (75 per row) of pressure chambers 23 in the row direction out of the number of nozzles 24 in the four rows. Arranged. Accordingly, as shown in FIGS. 1 and 3, one piezoelectric actuator 12a is disposed in the front half of the upper surface of the cavity unit 11 in the longitudinal direction (the first direction), and the other piezoelectric actuator 12b is disposed in the rear half. Be placed.

  Each piezoelectric actuator 12a (or 12b) is arranged corresponding to each position of the common electrode 37 and each pressure chamber 23, as will be described in detail later with reference to FIGS. The individual electrodes 36 are alternately stacked with the piezoelectric sheet interposed therebetween, and a voltage is applied between the arbitrary individual electrode 36 and the common electrode 37, so that the piezoelectric sheet corresponding to the applied individual electrode 36 is formed. In the active portion, distortion due to the piezoelectric longitudinal effect occurs in the stacking direction. The active portions are formed in the same number in the same row with the same number as the number of pressure chambers 23.

  That is, the active portions are arranged along the row direction (first direction) of the nozzles 24 (pressure chambers 23) and in the second direction by the same number as the number of the nozzle rows (four). Are lined up. Each active part is formed long in the longitudinal direction of the pressure chamber 23 in the second direction (the width direction of the cavity unit 11, the Y-axis direction), and the arrangement interval (pitch P) between adjacent active parts is also described later. The pressure chambers 23 are arranged in a staggered manner (see FIG. 3).

  The pressure chambers 23 are arranged in two groups in the longitudinal direction of the base plate 22 corresponding to the two piezoelectric actuators 12a and 12b. In other words, the pressure chambers 23 of the group corresponding to one actuator 12a correspond to those in the first half of the row direction (first direction) of the nozzles 24, and the pressure chambers 23 of the group corresponding to the other actuator 12b are Corresponding to the latter half of the nozzle 24 in the row direction (first direction), two sets of two staggered arrays each having the same interval as the arrangement interval (pitch P) of the nozzles 24, for a total of four rows (See FIG. 1).

  Each of the pressure chambers 23 is formed so as to be long in the width direction (second direction) of the base plate 22 and penetrate the base plate 22 in the thickness direction. The inlet 23b of each pressure chamber 23 communicates with a manifold chamber 26 described later via a second ink passage 30, a throttle portion 28, and a first ink passage 29 formed in the spacer plates 19, 20, and 21 (FIG. 2). And FIG. 4).

  In addition, the outflow end 23 a of each pressure chamber 23 is ink formed on the spacer plates 19, 20, 21, the manifold plates 17, 18, the damper plate 16, and the intermediate plate 15 positioned between the base plate 22 and the nozzle plate 14. Each of the communication passages 25 is communicated with each nozzle 24 via each communication passage 25 as a flow passage. A part of this communication passage 25 is at least one of the plates 15 to 21 stacked between the base plate 22 and the nozzle plate 14. The (one layer) plate is provided with a concave groove-like flow passage 50 substantially parallel to the flat plate surface (front surface or back surface), so that the position of the nozzle 24 corresponding to each pressure chamber 23 can be determined. A straight line (perpendicular line) perpendicular to the surface of the base plate 24 extends from the outflow end 23a (ink outflow portion) of the nozzle plate 14 to the nozzle plate 14. , In which can be set in the lateral direction (direction along the first direction of the plate, X-axis direction) to the distance L3 shifted position (see FIGS. 2 and 3).

  That is, as shown in FIGS. 1 and 3, the distance L2 between the two groups of pressure chambers 23 is set to be larger than the arrangement interval (pitch P) of the pressure chambers 23 in the longitudinal direction of the base plate 22. This is because, in manufacturing each piezoelectric actuator 12a, 12b, the distance L1 between the individual electrodes 36, 36 at the end of the row and the one end 44 (one end 45 of the other piezoelectric actuator 12b) of the piezoelectric actuator 12a adjacent to it. Since it is difficult to manufacture the individual electrodes 36 to be equal to or less than ½ of the pitch P, the distance L1 is set to a size that facilitates the manufacture of the piezoelectric actuators 12a and 12b, and a larger interval L2 is set.

  Then, one end 44 of one piezoelectric actuator 12a and one end 45 of the other piezoelectric actuator 12b adjacent to each other are opposed to each other, and the distance between the opposing ends 44, 45 is separated by a distance L4. Both piezoelectric actuators 12a and 12b are arranged in series (see FIGS. 1 and 3).

  As a result, the pitch P of the nozzles 24 is set to be constant in the row direction, but the distance L3 in the lateral direction is perpendicular to the line (perpendicular line) perpendicular to the plate thickness of the corresponding pressure chamber 23. Therefore, at least a part of the communication passage 25 connected from the outflow end 23a of each corresponding pressure chamber 23 to the nozzle 24 is at least partly connected to the flat plate surface of the plate as described above. With this configuration, the lateral passage 25 in the other plate is vertically penetrated in the plate thickness direction of each plate, and is simply communicated with one end portion and the other end portion of the concave groove communication passage 50. It can be made to correspond. The groove-shaped communication path 50 extends in the extending direction of the pressure chamber 23 together with the lateral displacement and is inclined symmetrically with respect to the center of the interval L2 between the two groups of pressure chambers 23.

  In the present embodiment, the groove-shaped communication path 50 is provided in the third spacer plate 21 adjacent to the lower surface side of the base plate 22 provided with the pressure chamber 23. More specifically, as shown in FIGS. 5 and 6, the first concave groove-shaped communication path 50 a opened to the front surface (upper surface) side of the third spacer plate 21, and the rear surface (lower surface) of the third spacer plate 21. ) And the second groove-shaped communication path 50b opened on the side are alternately provided.

  The first groove-shaped communication path 50a is open on the upper surface of the third spacer plate 21, and has a groove shape formed by etching by leaving the lower half of the plate thickness of the third spacer plate 21. The upper open surface is sealed with a base plate 22 adjacent to the upper surface, with one end 51 a communicating with the outflow end 23 a of the corresponding pressure chamber 23. The other end opening 52a of the concave groove-shaped communication path 50a penetrates the lower surface side of the third spacer plate 21 and is connected to the communication path 25 formed through and penetrating the second spacer plate 20 adjacent to the lower side. Communicate.

  A second groove-shaped communication path 50 b communicating with the outflow end 23 a of the other pressure chamber 23 adjacent to the one pressure chamber 23 is opened to the lower surface of the third spacer plate 21, and the plate of the third spacer plate 21. Of the thickness, it is a concave groove formed by etching so as to leave the upper half, and its lower open surface has a communicating path 25 that is formed by penetrating through the second spacer plate 20 adjacent to the lower end 52b. And is sealed by the second spacer plate 20. One end 51 b of the second groove-shaped communication path 50 b penetrates the upper surface side of the third spacer plate 21 and communicates with the outflow end 23 a of the corresponding pressure chamber 23.

  In the embodiment, the plane area of the first opening 51 a (51 b) communicating with the outflow end 23 a of the pressure chamber 23 is set larger than the plane area of the second opening 52 a (52 b) communicating with the communication path 25. .

  As described above, the plurality of groove-shaped communication paths 50 formed in the third spacer plate 21 are opened to the first groove-shaped communication path 50a opened to the front surface side of the third spacer plate 21 and the back surface side. If the second concave groove-shaped communication paths 50b are alternately formed, the first concave groove-shaped communication paths 50a and the one corresponding to the second concave groove-shaped communication paths 50b of the cavity unit 11 Even when designed to be arranged close to each other in plan view, the third spacer plate 21 is isolated from the front and back surfaces and does not communicate with each other. Therefore, the communication path 25 as an ink flow path can be freely designed. The degree can be greatly improved.

  In particular, when the number of plates to be stacked in the cavity unit 11 is large, a part of the communication path 25 as an ink flow path from the pressure chamber 23 to the corresponding nozzle 24 is parallel to the plane of the plate. The position of the nozzle 24 corresponding to the pressure chamber 23 is greatly displaced in plan view by adopting a shape that is formed in the extending groove-shaped communication passage 50b and the other communication passage 25 is penetrated in a direction perpendicular to the plane of the plate. Even so, it is possible to design an ink flow path that allows both to communicate easily. Further, it is also possible to control so that the total length (the distance including the concave groove-shaped communication path 50a or the concave groove-shaped communication path 50b) of the communication path 25 as the ink flow path from each pressure chamber 23 to the corresponding nozzle 24 is equal. It becomes extremely easy.

  A manifold chamber 26 is formed in the two manifold plates 17 and 18 so as to extend along the row of the nozzles 24. More specifically, the length of each manifold chamber 26 is a length obtained by dividing the pressure chambers 23 arranged in the direction of each nozzle row into appropriate numbers. In the embodiment, one group (one group of pressure chambers 23) is provided. The number of the pressure chambers 23 in one row is 75), and the cavity unit 11 has four rows of the pressure chambers 23, and is arranged for each row. Therefore, in the embodiment, eight manifold chambers 26 are formed. One end portion in the longitudinal direction of each manifold chamber 26 communicates with the ink supply holes 31 formed in the end portions of the spacer plates 19 to 21 and the base plate 22 stacked thereabove. A filter 32 for removing dust in ink supplied from an ink supply source such as an ink tank (not shown) is stretched on the upper surface of the ink supply hole 31 formed in the end of the uppermost base plate 22. .

  Further, the depth of each manifold chamber 26 is formed by etching or the like so as to cover the entire plate thickness of the manifold plates 17 and 18, and the first spacer plate on the upper layer of the manifold plates 17 and 18 obtained by combining these two plates. 19 and a lower damper plate 16 are stacked so as to be hermetically sealed. The damper plate 16 is formed with a damper chamber 27 having the same shape as the manifold chamber 26 in plan view and having a plate thickness reduced by etching on the lower surface side.

  Of the pressure waves acting on the pressure chamber 23 by driving the piezoelectric actuator 12, the retreat component toward the manifold chamber 26 is absorbed by the vibration of the damper plate 16 having a thin plate thickness to prevent so-called crosstalk. To do.

  The second spacer plate 20 is formed with an ink flow restricting portion 28 corresponding to each pressure chamber 23. As shown in FIG. 4B, the diaphragm portion 28 is formed so that the area of both end portions 28a and 28b in the longitudinal direction is large and the intermediate area is small. In addition, the longitudinal direction of each throttle portion 28 is formed to be parallel to the longitudinal direction of the pressure chamber 23. Then, the first spacer plate 19 is laminated on the lower surface side of the second spacer plate 20, and the third spacer plate 21 is laminated on the upper surface side, whereby the narrowed portion 28 is sealed. A first ink passage 29 formed in the first spacer plate 19 communicates the manifold chamber 26 with one end portion 28 a of the throttle portion 28. On the other hand, the second ink passage 30 formed in the third spacer plate 21 communicates the other end portion 28b of the throttle portion 28 with the inlet end 23b of the pressure chamber 23 (FIGS. 2 and 4A). reference).

  On the other hand, as shown in FIG. 5, each of the piezoelectric actuators 12 is composed of a plurality of (seven in the embodiment) piezoelectric sheets 33 and 34 made of piezoelectric ceramic plates each having a thickness of about 30 μm. In this structure, a constraining layer composed of two sheets 46 and 47 is laminated on the upper surface of the group, and a top sheet 35 is further laminated on the upper surface. The sheet and the top sheet of the constraining layer may be piezoelectric ceramic plates or other materials as long as they have electrical insulation.

  As shown in FIG. 8, on the upper surface (flat plate surface) of the even-numbered piezoelectric sheet 33 counted upward from the lowermost piezoelectric sheet 34 having the common electrode 37, each pressure chamber 23 (indicated by a dotted line) in the cavity unit 11. The narrow individual electrodes 36-1, 36-2, 36-3, 36-4 are provided in the first direction (the long side direction of the piezoelectric sheet 33, the X-axis direction in FIG. It is formed in a row along the row direction of each nozzle 24.

  The individual electrodes 36-1 in the first row and the individual electrodes 36-4 in the fourth row are respectively arranged on the sides close to the side edges of the long sides of each pair of the piezoelectric sheets 33. Further, the individual electrode 36-2 in the second row and the individual electrode 36-3 in the third row are disposed at the central portion in the short side direction of each piezoelectric sheet 33.

  Each individual electrode 36-1, 36-2, 36-3, 36-4 is parallel to the short side of each piezoelectric sheet 33 along a second direction (Y-axis direction) orthogonal to the first direction. Extend to. In that case, the straight portions 36b of the individual electrodes 36-1, 36-2, 36-3, 36-4 are respectively connected to the pressure chambers 23-1, 23-2, 23-3, 23-4 (FIG. 8). It is substantially the same length as that of the dotted line) and overlaps in a plan view, and is formed in a straight line having a slightly narrower width than each pressure chamber. The end 36a where the individual electrode 36-1 in the first row and the individual electrode 36-2 in the second row face each other, the individual electrode 36-3 in the third row, and the individual electrode 36-4 in the fourth row. The end portions 36a facing each other are bent and formed in an inclined shape in plan view. The bending direction is a direction away from the opposite one end 44 (45) of the two piezoelectric actuators 12a and 12b in a plan view and extends in a direction in which both ends 36a and 36a approach each other (FIG. 8). reference).

  Each of the end portions 36a overlaps at least partly with a dummy electrode 38 in a vertically adjacent piezoelectric sheet 34 and a first connection pattern 53 (see FIG. 9) in a lower layer sheet 46 to be described later in plan view. 34 and the inner conductive electrodes 42a, 42b, and 60 that penetrate the lower sheet 46 are disposed at positions that can be electrically connected to each other (see FIG. 13).

  Further, the piezoelectric sheet 33 overlaps with a later-described common electrode 37 in plan view, surrounds the row of the individual electrodes 36-1 and 36-2, and the individual electrodes 36-3 and 36-4. A dummy common electrode 43 is formed so as to surround this column.

  The common electrode 37 is printed on each surface of the lowermost piezoelectric sheet 34 and the odd-numbered piezoelectric sheets 34 counted upward (see FIG. 7). The common electrode 37 is connected to the three trunk portions 37a, 37b, and 37c that are long in the first direction (X-axis direction, the direction along the long side of the piezoelectric sheet 34) of each piezoelectric sheet 34, and is connected to the piezoelectric sheet. 34, and a connecting portion 37e extending along the short side edge. The three trunk portions 37a, 37b, and 37c are formed at positions close to the pair of long side edges of the piezoelectric sheet 34 that are opposed to each other and at a midway portion in the short side direction (Y-axis direction) of the piezoelectric sheet 34. The trunk portion 37a is arranged at a position that overlaps most of the straight portion 36b of the individual electrode 36-1 in the first row in plan view. The trunk portion 37c is arranged at a position overlapping with most of the straight portion 36b in the individual electrode 36-4 in the fourth row in plan view. On the other hand, the trunk 37b on the center side is arranged at a position that overlaps most of the straight portions 36b of the individual electrode 36-2 in the second row and the individual electrode 36-3 in the third row in plan view. .

  Further, a plurality of comb teeth portions 37d extending in the Y-axis direction are connected to the trunk portions 37a, 37b, and 37c. The arrangement interval P of the comb-tooth portion 37d is set equal to the arrangement interval P of the individual electrodes 36-1, 36-2, 36-3, 36-4, and hence the arrangement interval P of the pressure chamber 23, and the straight line of each individual electrode. It arrange | positions so that the remaining part of the part 36b may overlap with planar view (refer FIG. 7).

  A substantially oval dummy electrode 38 (individually indicated by reference numerals 38-1, 38-2, 38-3, 38-4) in a plan view is provided at a portion between the rows of the comb teeth portions 37d facing each other. Are arranged at regular intervals so as to overlap with at least a part of each end 36a of each individual electrode 36-1, 36-2, 36-3, 36-4 in plan view.

  Except for the lowermost piezoelectric sheet 34, the upper piezoelectric sheets 34 and 33 are electrically connected to a plurality of locations of the common electrode 37 such as the trunks 37a, 37b, and 37c and the dummy common electrode 43 in the vertical direction. In order to connect, at the positions of the electrodes 37 and 43, conductive members (conductive paste) filled in a plurality of through-holes drilled so as to penetrate the thickness of the piezoelectric sheets 34 and 33, respectively. The internal conduction electrode 41 is formed. Similarly, end portions 36 a of the individual electrodes 36-1, 36-2, 36-3 and 36-4 in the plurality of piezoelectric sheets 33 and the dummy electrodes 38-1, 38-2 and 38 in the piezoelectric sheet 34. -3 and 38-4 are drilled through the thickness of each piezoelectric sheet 33 and 34 at the position of the end 36a and the electrode 38 in order to electrically connect each of them in the vertical direction. Internal conductive electrodes 42a and 42b are formed of conductive members (conductive paste) filled in the plurality of through holes provided. In that case, the internal conductive electrode 42a in the piezoelectric sheet 33 and the internal conductive electrode 42b in the piezoelectric sheet 34 are formed by appropriately separating the distance e1 at a position that does not overlap vertically in a plan view (see FIG. 6).

  On the upper surface of the lower sheet 46 of the two sheets 46, 47 as the constraining layer, as shown in FIG. 9, the first connection pattern 53 (individually, reference numeral 53- 1, 53-2, 53-3, and 53-4) overlap with at least a part of each of the dummy electrodes 38-1, 38-2, 38-3, and 38-4 in the piezoelectric sheet 34 in plan view. In this way, they are arranged at regular intervals. Further, at four corners on the upper surface of the lower layer sheet 46, contact patterns 54 are formed at positions overlapping with a part of the common electrode 37 in the piezoelectric sheet 34 in plan view.

  On the other hand, as shown in FIG. 10, on the upper surface of the upper layer sheet 47, a contact pattern 55 that overlaps with the common electrode 37 of the piezoelectric sheet 34 in the same size in plan view, and the lower layer The second connection so as to overlap at least a part of the first connection pattern 53 (individually indicated by reference numerals 53-1, 53-2, 53-3, 53-4) on the sheet 46 in plan view. The patterns 56 (individually indicated by reference numerals 56-1, 56-2, 56-3, 56-4) are arranged and formed at regular intervals.

  As shown in FIG. 11, a plurality of common conductive layers 57 are formed on the upper surface of the top sheet 35 so as to overlap a part of the contact pattern 55 in the upper layer sheet 47 in plan view. Further, on the top surface of the top sheet 35, the second connection patterns 56-1, 56-2, 56-3, and 56-4 in the upper layer sheet 47 are individually overlapped with each other in plan view. Conductive layers 58 (indicated individually by reference numerals 58-1, 58-2, 58-3, 58-4) are arranged and formed at regular intervals (see FIG. 14). As shown in FIG. 11, each of the individual conductive layers 58-1, 58-2, 58-3, 58-4 has a short edge (in the Y-axis direction) of the top sheet 35, and further, each individual electrode 36-1. , 36-2, 36-3, 36-4 and is formed in a straight line extending in the direction of the portion of the straight line portion 36b of each individual electrode, but shorter than the straight line portion 36b of each individual electrode. (Refer to FIG. 8 and FIG. 11 for comparison). Further, the individual conductive layers 58-1, 58-2, 58-3, 58-4 formed on the upper surface of the top sheet 235 are arranged in parallel below each other as shown in FIGS. Is positioned above the partition wall 70 between the pressure chambers 23 adjacent to each other. In FIG. 14, it is slightly shifted from the center of the partition wall 70, but it may be made coincident with the center.

  Furthermore, as shown in FIG. 11, the top sheet 35 has a common surface electrode 66 such as a rectangular shape in plan view as a back-end electrode for connection to the connection electrode 71 of the flat cables 13a and 13b. A front surface electrode 67 and a dummy portion 68 are formed (see FIG. 12). In that case, as shown in FIG. 15, the individual surface electrode 66 is flat on an appropriate portion in the length direction of each individual conductive layer 58-1, 58-2, 58-3, 58-4 in the top sheet 35. It is formed in an island shape so as to be partially and electrically connected partially in view, and the row direction (X-axis direction) of each individual conductive layer 58-1, 58-2, 58-3, 58-4 Are arranged in a zigzag pattern so as to be displaced in the Y-axis direction.

  In other words, in the illustrated embodiment, each individual surface electrode 66 is arranged at a position shifted by approximately half of their arrangement interval (pitch) P in plan view with respect to the corresponding pressure chamber 23 and thus the active part, And it will be arrange | positioned above the partition 70 between the adjacent pressure chambers 23 and 23 (refer FIG. 15).

  As a modification of this embodiment, the individual surface electrodes 66 arranged above the partition walls 70 between the adjacent pressure chambers 23 are arranged with respect to the corresponding pressure chambers 23 (active portions). The distance may be shifted in the X-axis direction by a distance of 1.5 times (pitch P).

  Further, as shown in FIGS. 3 and 15, the individual surface electrode 66 at a position closest to the opposing end portions 44, 45 of the piezoelectric actuators 12 a, 12 b arranged in series is the one end portion 44. , 45 is arranged so as to be biased so as to be larger than the distance L1 from the corresponding active portion and thus from the one end portion 44, 45 of the pressure chamber 23.

  The common surface electrode 67 is retrofitted in an island shape so as to overlap a part of the common conductive layer 57 formed on the upper surface of the top sheet 35 in a plan view. The dummy portion 68 is retrofitted in an island shape on the extension of the common conductive layer 57 in the X-axis direction. The electrode 67 and the dummy portion 68 are also located above the partition wall 70 as shown in FIG.

  Then, the dummy electrodes of the piezoelectric sheet 34 adjacent on the lower side are provided at the positions of the first connection patterns 53-1, 53-2, 53-3, 53-4 of the lower layer sheet 46, respectively. 38-1, 38-2, 38-3, 38-4 and a plurality of through holes drilled to penetrate through the thickness of the lower layer sheet 46 in order to electrically connect each of them in the vertical direction. Internal conductive electrodes 60 are formed of conductive members (conductive paste) filled in the holes (see FIG. 9).

  Further, in order to make an electrical connection in the vertical direction with the common electrode 37 of the piezoelectric sheet 34 adjacent on the lower side, the connection pattern 54 in the lower layer sheet 46 has a plurality of through holes similar to those described above. The internal conduction electrode 61 made of a conductive member filled in each is formed (see FIG. 9).

  Similarly, in the upper layer sheet 47, the locations of the second connection patterns 56-1, 56-2, 56-3, 56-4 and the first connection patterns 53-1, 53-2 of the lower layer sheet 46, The internal conductive electrode 62 and the through pattern 55 for electrically connecting the contact pattern 55 and the contact pattern 54 are electrically connected to the through holes in order to electrically connect the portions 53-3 and 53-4 individually. Internal conduction electrodes 63 are respectively formed in the holes (see FIG. 10).

  In the same manner as described above, the top sheet 35 is also provided with the positions of the individual conductive layers 58-1, 58-2, 58-3, 58-4 and the second connection pattern 56- in the upper layer sheet 47 adjacent to the bottom sheet 35-. An internal conduction electrode 64 is provided in the through hole in order to individually electrically connect the locations of 1, 56-2, 56-3, and 56-4. Internal conductive electrodes 65 are formed in the through holes in order to electrically connect the conductive layer 57 and the connecting pattern 55 in the upper layer sheet 47 adjacent below (see FIG. 11).

  When several sheets are stacked, the interior for vertically connecting between the individual electrodes 36 and the corresponding dummy electrodes 38, the first connection pattern 53, and the second connection pattern 56 in the adjacent sheets above and below It is preferable to arrange the conductive electrodes 42a, 42b, 60, 62, 64 at positions that do not overlap each other in plan view.

  In the present invention, the internal connection electrodes for electrically connecting the individual electrodes 36 to the individual surface electrodes 66 and the common surface electrodes 67 in the piezoelectric actuators 12a and 12b are the lower layer sheet 46 and the upper layer as the constraining layers. The first connection pattern 53, the second connection pattern 56, the individual conductive layer 58 formed along each plane of the sheet 47 and the top sheet 35, and the sheets 46, 47, 35 are arranged in the vertical direction (plate thickness). The concept includes internal conduction electrodes 60, 62, and 64 penetrating in the direction.

  As an example of the manufacturing method of the piezoelectric actuator 12, the piezoelectric sheets 33 and 34, the constraining layer sheets 46 and 47, and the top sheet 35 are all made of a ceramic plate. On the surface of a large green sheet made of a ceramic plate, a piezoelectric sheet 33, for each region constituting each operation unit, so that a plurality of operation units of the piezoelectric actuator 12 are integrally formed in a matrix. In 34, the electrode patterns of the individual electrode 36, the common electrode 37, and the dummy electrodes 38 and 43 are screen-printed with a conductive paste such as a silver-palladium paste (see FIGS. 7 and 8). On the upper and lower two constraining layer sheets 46 and 47, the first and second connection patterns 53 and 56 and the contact patterns 54 and 55 are similarly formed by screen printing using the conductive paste (FIGS. 9 and 10). reference). Then, each electrode pattern of the individual conductive layer 58 and the common conductive layer 57 is screen-printed with the conductive paste on the top sheet 35 (see FIG. 11).

  Note that the internal conductive electrodes 41, 42, 60 to 65 in the piezoelectric sheets 34 and 33, the upper and lower layer sheets 46 and 47, and the top sheet 35 excluding the lowermost piezoelectric sheet 34 are formed after the through holes in the plate thickness direction are formed. Pour the paste. Next, a plurality of material sheets are laminated in a state where the positions of the regions constituting the respective operation units are aligned vertically, and then pressed in the laminating direction and then fired.

  Next, on the upper surface of the top sheet 35, as a retrofitted electrode for connecting to the connection electrode 71 of the flat cables 13a and 13b, the individual surface electrode 66, the common surface electrode 67, and the dummy portion having a rectangular shape in plan view, etc. 68 are each screen-printed with a thick film and then dried (see FIG. 12). Since the electrodes 66 and 67 are not fired, the solderability with the connection electrodes 71 of the flat cables 13a and 13b can be improved later.

  An adhesive sheet (not shown) made of an ink non-permeable synthetic resin material as an adhesive layer is formed on the entire lower surface (a flat plate surface facing the pressure chamber 23) of the plate-type piezoelectric actuator 12 having such a configuration. ) Is applied in advance or a thermosetting adhesive is applied, and then the piezoelectric actuators 12a and 12b are applied to the cavity unit 11 and the individual electrodes 36 are applied to the pressure chambers 23 of the cavity unit 11, respectively. Correspondingly, the one end portions 44 and 45 are bonded and fixed with a distance L4 therebetween (see FIGS. 4A and 3).

  At this time, a planar jig is applied to the upper surfaces of the piezoelectric actuators 12a and 12b to push the piezoelectric actuators 12a and 12b toward the cavity unit 11, but the electrodes 66 projecting from the upper surfaces of the piezoelectric actuators 12a and 12b. , 67 and the dummy portion 68 correspond to the partition wall 70 between the pressure chambers 23 as shown in FIG. 12, and the adhesive on the partition wall 70 is caused to adhere to the piezoelectric actuator 12a by the pressing force acting through the electrode 66. , 12b are securely bonded to the partition wall 70. Therefore, ink leaks due to poor adhesion, and the pressing force does not act directly on the pressure chamber that is a cavity, so that the pressure chamber can be prevented from being deformed and the piezoelectric actuator can be prevented from cracking.

  Further, the flat cables 13a and 13b are pressed and bonded to the upper surfaces of the piezoelectric actuators 12a and 12b so that the various connection electrodes 71 of the flat cables 13a and 13b are connected to the individual surfaces. The electrode 66 and the common surface electrode 67 are electrically joined to each other.

  In this case, as in the case where the piezoelectric actuator and the cavity unit are bonded, each of the individual surface electrodes 66 is located above the partition wall 70 between the adjacent pressure chambers 23, so that the flexible flat cable 13a, The force which presses 13b to each piezoelectric actuator 12a, 12b upper surface can be enlarged, and electrical connection with the said connection electrode 71, each surface electrode 66, and the common surface electrode 67 can be perfected.

  In the embodiment, the first connection pattern for connecting the individual surface electrode 66 on the upper surface of the uppermost sheet of each piezoelectric actuator and the individual electrode 36 by inclining the end 36a of the individual electrode 36. 53, the second connection pattern 56, and the individual conductive layer 58 and the internal conduction electrodes 60, 62, 64 for connecting them vertically are individually separated from the one end 44 (45) in the X-axis direction. Thus, the position of the individual surface electrode 66 can also be biased so as to be greatly separated from the one end 44 (45) in the X-axis direction, and adjacent to the flat cables 13a and 13b to be arranged. A design that does not interfere with each other can be easily achieved by easily separating the intervals.

  Further, as shown in FIG. 15, by forming the individual surface electrode 66 on the island-shaped individual conductive layer 58 formed on the upper surface of the top sheet 35, the X-axis direction (the row direction of the nozzles 24) is formed. ), The arrangement position of the individual surface electrode 66 arranged so as to be separated from the one end 44 (45) can be further designed to be shifted within a predetermined range. Accordingly, the distance L5 from the opposing one end 44 (45) of the individual surface electrodes 66, 66 on the conductive layer formed on the upper surface of each of the piezoelectric actuators 12a, 12b arranged in series in the X-axis direction is set as follows. Similarly, if the first end portion 44 (45) and the active portion (pressure chamber 23) are biased so as to be separated from the active portion (pressure chamber 23), the distance from the side edge of each flat cable to the bonding electrode 71 is conventionally increased. Even if the road is large, both the flat cables 13a and 13b are joined to the piezoelectric actuators 12a and 12b in a state where they do not overlap with each other at the opposite ends 44 and 45 (a state where they do not interfere with each other). Can be arranged.

  The individual surface electrode 66 and the common surface electrode 67 are omitted, and the connection electrodes 71 of the flat cables 13 a and 13 b are directly connected to the individual conductive layer 58 and the common conductive layer 57 exposed on the upper surface of the top sheet 35. May be joined.

  In this configuration, by applying a high voltage for polarization between all the individual electrodes 36 and the common electrode 37 via the individual surface electrodes 66 and the common surface electrodes 67 in the piezoelectric actuators 12a and 12b, The portions of the piezoelectric sheets 33 and 34 sandwiched between the individual electrodes 36 and the common electrode 37 are polarized. As a result, the portions of the piezoelectric sheets 33 and 34 sandwiched between the individual electrodes 36 and the common electrode 37 serve as active portions. Then, a driving voltage is applied between the individual electrode 36 and the common electrode 37 via an arbitrary individual surface electrode 66 and a common surface electrode 67 to generate an electric field parallel to the polarization direction in the corresponding active portion. As a result, the active portion extends in the stacking direction, the internal volume of the corresponding pressure chamber 23 is reduced, and the ink in the pressure chamber 23 is ejected from the corresponding nozzle 24 in the form of droplets, and a predetermined printing is performed. Is done.

  When four colors of ink (black, cyan, yellow, magenta) are used in color printing, for example, the first row of nozzles 24-1 is used for discharging black ink, and the second row of nozzles 24- When 2 is set to discharge cyan ink, the third row nozzle 24-3 is set to discharge yellow ink, and the fourth row nozzle 24-4 is set to discharge magenta ink, the first formed on the corresponding manifold plate 17 (18). The manifold chamber 26 in the row is filled with black ink, the manifold chamber 26 in the second row is filled with cyan ink, the manifold chamber 26 in the third row is filled with yellow ink, and the fourth row The manifold chamber 26 is filled with magenta ink.

  As described above, in the present embodiment, the pressure chamber 23 is divided into two groups along the row direction of the nozzles 24, and the interval between the groups is increased to L2. Since at least a part of the communication passage 25 communicating with each other is constituted by a concave groove-like flow passage 50 substantially parallel to the flat plate surface of one plate, the arrangement interval (pitch) of the nozzles 24 is set. When a head having a large number of nozzles is manufactured while keeping the same as the conventional one, the piezoelectric actuators 12a and 12b can be used by arranging the nozzles 24 having a short length in the row direction.

  Accordingly, since the amount of contraction when firing each actuator when the piezoelectric actuator is manufactured is reduced, the variation in the interval between the active portions can be reduced, and a piezoelectric actuator with high dimensional accuracy can be manufactured efficiently.

  Moreover, in the said embodiment, although the row | line | column of the nozzle was 4 rows, it can apply with respect to 1 or more nozzle rows in this invention. Needless to say, the present invention can be applied to the joining of a single piezoelectric actuator and a single cable member.

FIG. 2 is a perspective view showing a cavity unit, a piezoelectric actuator, and a flat cable separately of the piezoelectric inkjet printer head according to the first embodiment of the present invention. It is a partial exploded perspective view of a cavity unit. It is an III-III arrow expanded sectional view of FIG. FIG. 4A is an enlarged sectional view taken along the line IV-IV in FIG. 1, and FIG. It is a partial expanded sectional view of a piezoelectric actuator. It is a partial expansion perspective view which shows the position of the individual electrode in a piezoelectric sheet, a dummy electrode, and those internal conduction electrodes. It is a partially cutaway enlarged plan view of a piezoelectric sheet showing a pattern such as a common electrode. It is a partially cutaway enlarged plan view of a piezoelectric sheet showing patterns of individual electrodes and the like. It is a partially cutout enlarged plan view showing a pattern in a lower layer sheet. It is a partially notched enlarged plan view showing a pattern in the upper layer sheet. It is a partially notched enlarged plan view which shows patterns, such as an individual conductive layer, in a top sheet. It is a partially cutout enlarged plan view showing a pattern of individual surface electrodes and the like on the top sheet. It is a partially notched enlarged plan view showing the overlapping relationship between the individual electrode and the dummy electrode with respect to the pressure chamber in the active part. FIG. 5 is a partially cutaway enlarged plan view showing an overlapping relationship among individual electrodes, first and second connection patterns, and individual conductive layers with respect to a pressure chamber in a plan view of the top sheet. It is a partially notched enlarged plan view showing the overlapping relationship among the individual electrode, the individual conductive layer, and the individual surface electrode with respect to the pressure chamber in a plan view of the top sheet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inkjet printer head 11 Cavity unit 12 Piezoelectric actuator 13 Flat cable 22 Base plate 23 Pressure chamber 24 Nozzle 33, 34 Piezoelectric sheet 36 Individual electrode 37 Common electrode 38 Dummy electrode 41, 42, 60-65 Internal conduction electrode 43 Dummy common electrode 53 1st 1 connection pattern 54, 55 contact pattern 56 second connection pattern 57 common conductive layer 58 individual conductive layer 66 individual surface electrode 67 common surface electrode

Claims (12)

A piezoelectric unit having an active portion that can be selectively driven for each pressure chamber in a cavity unit that includes a plurality of nozzles that eject ink and a plurality of pressure chambers that communicate with each nozzle and are arranged at predetermined intervals. In an ink jet printer head formed by joining an actuator and ejecting ink in the pressure chamber from the nozzle by driving the active part,
The piezoelectric actuator includes a plurality of stacked sheets including a piezoelectric sheet, a plurality of individual electrodes positioned corresponding to the plurality of pressure chambers and forming a row corresponding to the row of the pressure chambers, and the individual electrodes A common electrode having the piezoelectric sheet sandwiched in the stacking direction as the active portion, and a plurality of individual surface electrodes located on the upper surface of the uppermost sheet and connected to the individual electrodes via internal connection electrodes And
Each of the individual electrodes has an end connected to the internal connection electrode extending from the portion corresponding to the pressure chamber in the column direction so as to be positioned between the pressure chamber and the adjacent pressure chamber. Inkjet printer head characterized.   The pressure chambers are provided in a plurality of rows, the individual electrodes are provided in a plurality of rows corresponding thereto, and two adjacent rows among the plurality of rows of the individual electrodes are arranged such that end portions of the individual electrodes facing each other are arranged in the rows 2. The inkjet printer head according to claim 1, wherein the inkjet printer head extends in a direction and toward another row.   A plurality of the piezoelectric sheets, a plurality of the individual electrodes sandwiching the piezoelectric sheet together with the common electrode are provided in the stacking direction, and the individual electrodes in the stacking direction have the end portions extending in the same direction. The ink jet printer head according to claim 1 or 2, wherein   The internal connection electrode includes an internal conduction electrode filled in a through hole penetrating a sheet between the individual electrode and the individual surface electrode among the plurality of sheets. The inkjet printer head according to any one of 3.   A plurality of the piezoelectric sheets, a plurality of the individual electrodes sandwiching the piezoelectric sheet together with the common electrode in the stacking direction, in the same plane as the common electrode between the individual electrode and the individual surface electrode, The inkjet printer head according to claim 4, further comprising a dummy electrode corresponding to an end portion, wherein the end portion and the dummy electrode are connected via the internal conductive electrode.   6. The ink jet printer head according to claim 5, wherein the internal conductive electrodes of the sheets adjacent to each other in the stacking direction are located at a distance so as not to overlap each other in plan view. A plurality of sheets formed by laminating comprises a piezoelectric sheet, the plurality of individual electrodes a row at predetermined intervals in the surface direction of the sheet, that together with the individual electrodes sandwiching the piezoelectric sheet in the laminating direction thereof piezoelectric sheet said active portion A plurality of individual surface electrodes located on the upper surface of the uppermost sheet and connected to each individual electrode via an internal connection electrode,
Each of the individual electrodes has an end connected to the internal connection electrode extending in the column direction so as to be located between the individual electrode and an adjacent individual electrode from a portion forming the active portion. A characteristic piezoelectric actuator.   A plurality of rows of the individual electrodes are provided, and two adjacent rows of the plurality of rows of the individual electrodes extend end portions of the individual electrodes facing each other in the row direction and toward other rows. The piezoelectric actuator according to claim 7.   A plurality of the piezoelectric sheets, a plurality of the individual electrodes sandwiching the piezoelectric sheet together with the common electrode are provided in the stacking direction, and the individual electrodes in the stacking direction have the end portions extending in the same direction. The piezoelectric actuator according to claim 7 or 8, characterized in that   The internal connection electrode includes an internal conduction electrode filled in a through hole penetrating a sheet between the individual electrode and the individual surface electrode among the plurality of sheets. The piezoelectric actuator according to any one of 9. A plurality of the piezoelectric sheets, a plurality of the individual electrodes sandwiching the piezoelectric sheet together with the common electrode in the stacking direction, in the same plane as the common electrode between the individual electrode and the individual surface electrode, The piezoelectric actuator according to claim 10, further comprising a dummy electrode corresponding to an end portion, wherein the end portion and the dummy electrode are connected via the internal conduction electrode.   The piezoelectric actuator according to claim 11, wherein the internal conductive electrodes of the sheets adjacent to each other in the stacking direction are located at a distance so as not to overlap each other in plan view.

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