JP2022128659A - Piezoelectric actuator and manufacturing method for the same - Google Patents

Abstract

To suppress a difference in electrostatic capacitance between actuators.SOLUTION: A piezoelectric actuator 22 comprises first to third piezoelectric layers and first to third electrode layers. A low-potential electrode 53 constituting the third electrode layer 73 is formed on a surface of the third piezoelectric layer 43 positioned at a lowermost layer of the first to third electrode layers. A branch part 533 positioned at one end in a Y-direction (a left end shown by a figure 9) of a plurality of branch parts 533 of the low-potential electrode 53 is smaller in width than the branch parts 533 at positions other than the end part in the Y-direction (a center other than left and right ends shown by the figure 9).SELECTED DRAWING: Figure 9

Description

The present invention relates to a piezoelectric actuator composed of a plurality of piezoelectric layers and a plurality of electrode layers, and a manufacturing method thereof.

In Patent Document 1, an individual electrode (drive electrode) is provided on the surface of an upper piezoelectric layer (first piezoelectric layer), an intermediate common electrode (first potential electrode) is provided on the surface of an intermediate piezoelectric layer (second piezoelectric layer), and a lower piezoelectric layer is provided. Piezoelectric actuators are shown in which lower common electrodes (second potential electrodes) are respectively arranged on the surface of the (third piezoelectric layer). The intermediate common electrode (first potential electrode) and the lower common electrode (second potential electrode) each have a plurality of projecting portions (individual portions) having portions that overlap each of the plurality of individual electrodes in the stacking direction (first direction). , a plurality of extending portions (branch portions) extending in the conveying direction (second direction) and connecting the plurality of projecting portions, and a plurality of extending portions (branch portions) extending in the scanning direction (third direction). and a connecting extension (trunk).

Japanese Patent Application Laid-Open No. 2019-171681 (Figs. 5, 7, 8)

When each electrode is formed by screen printing, bleeding tends to occur downstream of each electrode in the printing direction of screen printing. Here, the branch portion is an element that constitutes the actuator portion together with the drive electrode. It gets bigger.

In addition, the end portion of the piezoelectric actuator tends to warp upward, and force is applied locally when the piezoelectric actuator is adhered to the flow path member or the like. At this time, a large tensile stress acts on the branch portion positioned at the end portion in the third direction, and the electrostatic capacity of the actuator portion configured by the branch portion increases.

At the actuator portion located at the end in the third direction, the increase in capacitance due to bleeding and the increase in capacitance due to the tensile stress during bonding as described above occur. At the actuator portion located other than the portion, an increase in capacitance due to bleeding occurs, but an increase in capacitance due to tensile stress during adhesion does not occur. Therefore, a difference in capacitance (and deformation performance) occurs between the actuator portion positioned at the end in the third direction and the actuator portion positioned at a position other than the end in the third direction.

SUMMARY OF THE INVENTION An object of the present invention is to provide a piezoelectric actuator capable of suppressing a difference in capacitance between actuator portions, and a method of manufacturing the same.

According to the first aspect of the present invention, a first piezoelectric layer, a second piezoelectric layer laminated on the first piezoelectric layer in a first direction along the thickness direction of the first piezoelectric layer, a third piezoelectric layer laminated in the first direction with respect to the first piezoelectric layer and the second piezoelectric layer and sandwiching the second piezoelectric layer with the first piezoelectric layer; a first electrode layer disposed on a surface of the piezoelectric layer opposite to the second piezoelectric layer; and a second electrode layer disposed between the first piezoelectric layer and the second piezoelectric layer in the first direction. and a third electrode layer disposed between the second piezoelectric layer and the third piezoelectric layer in the first direction, wherein the first electrode layers each including a plurality of drive electrodes to which either a potential or a second potential different from the first potential is selectively applied, wherein the second electrode layer includes a first potential electrode held at the first potential; The third electrode layer includes a second potential electrode held at the second potential, and at least one of the first potential electrode and the second potential electrode is aligned with each of the plurality of drive electrodes and the first direction. a plurality of individual portions having overlapping portions, a plurality of branch portions extending in a second direction perpendicular to the first direction and connecting the plurality of individual portions, and a plurality of branch portions perpendicular to the first direction and the second direction a trunk extending in a third direction and connecting the plurality of branch portions, and among the plurality of branch portions, a branch portion positioned at one end in the third direction is located at an end other than the end portion in the third direction. Piezoelectric actuators are provided, characterized in that the width is smaller than the branches on which they are located.

According to a second aspect of the present invention, a first piezoelectric layer; a second piezoelectric layer laminated on the first piezoelectric layer in a first direction along the thickness direction of the first piezoelectric layer; a third piezoelectric layer laminated in the first direction with respect to the first piezoelectric layer and the second piezoelectric layer and sandwiching the second piezoelectric layer between itself and the first piezoelectric layer; A first electrode layer is formed on the surface of the first piezoelectric layer, the first electrode layer including a plurality of drive electrodes to which either a first potential or a second potential different from the first potential is selectively applied. a second electrode layer including a first potential electrode held at the first potential is formed on the surface of the second piezoelectric layer; and a second electrode layer held at the second potential is formed on the surface of the third piezoelectric layer. forming a third electrode layer including a two-potential electrode, the first electrode layer being disposed on a surface of the first piezoelectric layer opposite to the second piezoelectric layer in the first direction, the second electrode layer being disposed between the first piezoelectric layer and the second piezoelectric layer in the first direction, and wherein the third electrode layer is between the second piezoelectric layer and the third piezoelectric layer in the first direction; When forming the second electrode layer and forming the third electrode layer, the first piezoelectric layer, the second piezoelectric layer, and the third piezoelectric layer are laminated in the first direction so as to be arranged in In at least one of the above, a plurality of individual portions, a plurality of branch portions extending in a second direction orthogonal to the first direction and connecting the plurality of individual portions, the first direction and the second direction At least one of the first potential electrode and the second potential electrode is formed so as to include a trunk extending in a third direction orthogonal to and connecting the plurality of branch portions, the first piezoelectric layer, the When the second piezoelectric layer and the third piezoelectric layer are laminated in the first direction, the first piezoelectric layer is arranged such that the plurality of individual portions have portions overlapping the plurality of drive electrodes in the first direction. When stacking the piezoelectric layer, the second piezoelectric layer, and the third piezoelectric layer in the first direction, and forming the second electrode layer and/or forming the third electrode layer, at least one of The first potential electrode and A method for manufacturing a piezoelectric actuator is provided, characterized in that at least one of the second potential electrodes is formed by screen printing along the third direction.

1 is an overall configuration diagram of a printer 1 including piezoelectric actuators according to a first embodiment of the present invention; FIG. 2 is a plan view of the head 3 shown in FIG. 1; FIG. 3 is an enlarged view of region III of FIG. 2; FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 3; FIG. FIG. 4 is a cross-sectional view taken along line VV of FIG. 3; 6A and 6B are diagrams showing the operation of the actuator section 90 in the cross section of FIG. 5. FIG. 4 is a plan view showing the upper surface of the uppermost piezoelectric layer 41 among the three piezoelectric layers 41 to 43 forming the piezoelectric actuator 22. FIG. 3 is a plan view showing the upper surface of an intermediate piezoelectric layer 42 among the three piezoelectric layers 41 to 43 forming the piezoelectric actuator 22. FIG. 4 is a plan view showing the upper surface of the lowermost piezoelectric layer 43 among the three piezoelectric layers 41 to 43 forming the piezoelectric actuator 22. FIG. 4 is a flowchart showing a method of manufacturing the piezoelectric actuator 22; FIG. FIG. 7 is a diagram showing a process of forming an electrode layer 73 on the upper surface of the piezoelectric layer 43 by screen printing; FIG. 10 is a view equivalent to FIG. 9 showing a piezoelectric actuator 222 according to a second embodiment of the present invention;

In the following description, the Z direction is vertical, and the X and Y directions are horizontal. Both the X and Y directions are orthogonal to the Z direction. The X direction is orthogonal to the Y direction.

<Overall configuration of the printer>
First, referring to FIG. 1, the overall configuration of a printer 1 including piezoelectric actuators according to the first embodiment of the present invention will be described.

The printer 1 has a head 3 , a carriage 2 and two transport roller pairs 4 .

The carriage 2 is supported by two guide rails 5 extending in the Y direction and is movable along the guide rails 5 in the Y direction.

The head 3 is of a serial type, is mounted on the carriage 2, and is movable together with the carriage 2 in the Y direction. A plurality of nozzles 15 are formed on the lower surface of the head 3 .

The two transport roller pairs 4 are arranged across the carriage 2 in the X direction. As the transport roller pair 4 rotates while nipping the paper P, the paper P is transported in the transport direction along the X direction.

A control unit (not shown) of the printer 1 performs an ejection operation for ejecting ink from the nozzles 15 while moving the head 3 in the Y direction together with the carriage 2, and transports the paper P by a predetermined amount in the transport direction with the pair of transport rollers 4. Alternate between actions. Thus, an image is recorded on the paper P. FIG.

<Head configuration>
The head 3, as shown in FIG. 2, has a channel unit 21 and a piezoelectric actuator 22 according to the first embodiment of the invention. Both the channel unit 21 and the piezoelectric actuator 22 have a rectangular shape in which the length in the X direction is longer than the length in the Y direction on a plane orthogonal to the Z direction.

<Configuration of channel unit>
As shown in FIG. 4, the channel unit 21 is composed of four metal plates 31 to 34 stacked in the Z direction.

A plurality of pressure chambers 10 are formed in the plate 31 . Communicating passages 12 and 13 are formed in the plate 32 for each pressure chamber 10 . The communicating passages 12 and 13 respectively overlap one end and the other end in the Y direction of the corresponding pressure chamber 10 in the Z direction. A communicating path 14 is formed in the plate 33 for each communicating path 13 . The communication path 14 overlaps the corresponding communication path 13 in the Z direction. Eleven manifold channels 11 are further formed in the plate 33 . The manifold channel 11 is provided for each row 10R (see FIG. 2) of the pressure chambers 10 arranged in the X direction. Each manifold flow path 11 extends in the X direction and communicates with a plurality of pressure chambers 10 belonging to the corresponding row 10R via communication paths 12 . A plurality of nozzles 15 are formed in the plate 34 . Each nozzle 15 overlaps the communicating path 14 in the Z direction.

On the upper surface of the plate 31, four ink supply ports 8 are formed in areas where the piezoelectric actuators 22 are not arranged (see FIG. 2). Each ink supply port 8 communicates with an ink cartridge (not shown) and communicates with three manifold channels 11 . Ink supplied to each ink supply port 8 from an ink cartridge is supplied to three manifold channels 11 . Ink is supplied from each manifold channel 11 through a communication path 12 to a plurality of pressure chambers 10 belonging to each row 10R. By driving the piezoelectric actuator 22 as described later, pressure is applied to the ink in the pressure chamber 10 , and the ink is discharged from the nozzle 15 through the communication paths 13 and 14 .

<Configuration of Piezoelectric Actuator>
The piezoelectric actuator 22 is arranged on the upper surface of the channel unit 21, as shown in FIG. The piezoelectric actuator 22 has three piezoelectric layers 41-43 and three electrode layers 71-73.

The three piezoelectric layers 41 to 43 are laminated in the Z direction with the Z direction as the thickness direction. The piezoelectric layer 42 is laminated on the piezoelectric layer 41 in the Z direction. The piezoelectric layer 43 is laminated on the piezoelectric layers 41 and 42 in the Z direction, and sandwiches the piezoelectric layer 42 with the piezoelectric layer 41 . The Z direction corresponds to the "first direction" of the invention. The piezoelectric layer 41 corresponds to the "first piezoelectric layer" of the invention, the piezoelectric layer 42 corresponds to the "second piezoelectric layer" of the invention, and the piezoelectric layer 43 corresponds to the "third piezoelectric layer" of the invention. .

The thicknesses of the piezoelectric layers 41 to 43 are the same (approximately 10 to 15 μm), and the total thickness of the piezoelectric layers 41 to 43 is approximately 30 to 45 μm. Each of the piezoelectric layers 41 to 43 is made of a piezoelectric material containing lead zirconate titanate or the like as a main component.

A piezoelectric layer 43 is arranged on the upper surface of the plate 31 and covers all the pressure chambers 10 formed in the plate 31 . The piezoelectric actuator 22 and the channel unit 21 are adhered to each other with an adhesive (not shown) placed between the piezoelectric layer 43 and the plate 31 .

The electrode layer 71 is arranged on the upper surface of the piezoelectric layer 41 (the surface of the piezoelectric layer 41 opposite to the piezoelectric layer 42 in the Z direction). The electrode layer 72 is arranged on the upper surface of the piezoelectric layer 42 (between the piezoelectric layers 41 and 42 in the Z direction). The electrode layer 73 is arranged on the upper surface of the piezoelectric layer 43 (between the piezoelectric layers 42 and 43 in the Z direction). The electrode layer 71 corresponds to the "first electrode layer" of the present invention, the electrode layer 72 corresponds to the "second electrode layer" of the present invention, and the electrode layer 73 corresponds to the "third electrode layer" of the present invention. .

The thickness of each of the electrode layers 71-73 in the Z direction is 0.5-1.5 μm. The electrode layers 71 and 72 have the same thickness. The thickness of the electrode layer 73 is greater than the thickness of each of the electrode layers 71 and 72 (see FIGS. 4 to 6).

The electrode layer 71 includes a plurality of drive electrodes 51, a plurality of dummy electrodes 59, two high potential connection electrode portions 54, and two low potential connection electrode portions 55, as shown in FIG.

A plurality of drive electrodes 51 are arranged corresponding to each of the pressure chambers 10 . Each drive electrode 51 has a main portion 51a and a projecting portion 51b. The main portion 51a overlaps substantially the entire corresponding pressure chamber 10 in the Z direction. The protruding portion 51b protrudes from the main portion 51a in the Y direction and does not overlap the corresponding pressure chamber 10 in the Z direction. A contact electrically connected to a COF (Chip On Film) (not shown) is provided on the projecting portion 51b. A driver IC (not shown) mounted on the COF individually applies either a high potential (VDD potential) or a low potential (GND potential) to each drive electrode 51 through the wiring of the COF under the control of the control unit. or is selectively given.

The plurality of drive electrodes 51 are arranged in the X direction in the central region of the upper surface of the piezoelectric layer 41 (the region excluding both ends in the X direction and both ends in the Y direction of the piezoelectric layer 41). 2) are formed. The plurality of drive electrode rows 51R are arranged in the Y direction.

Dummy electrodes 59 are provided on one side (upper side in FIG. 7) and the other side (lower side in FIG. 7) in the X direction for each drive electrode row 51R. The dummy electrodes 59 have the same size and shape on a plane perpendicular to the Z direction as the drive electrodes 51 belonging to the corresponding drive electrode row 51R, and are arranged at equal intervals in the X direction together with the drive electrodes 51 . The dummy electrode 59 is not electrically connected to the COF and is not given a potential. By providing the dummy electrode 59, it is possible to suppress the difference in the amount of contraction due to electrode formation between the drive electrode 51 at the center in the X direction and the drive electrode 51 at the end in the X direction in each drive electrode row 51R. It is possible to suppress the variation in the discharge amount from the plurality of nozzles 15 corresponding to the electrode row 51R.

The two high-potential connection electrode portions 54 are arranged at one end (the left end in FIG. 7) and the other end (the right end in FIG. 7) of the piezoelectric layer 41 in the Y direction, respectively. above). The two low-potential connection electrode portions 55 are arranged at one end (the left end in FIG. 7) and the other end (the right end in FIG. 7) of the piezoelectric layer 41 in the Y direction, respectively. bottom).

Each of the two high-potential connection electrode portions 54 is composed of eight connection electrodes 54a spaced apart from each other in the X direction. Each of the two low-potential connection electrode portions 55 is composed of eight connection electrodes 55a spaced apart from each other in the X direction. The connection electrodes 54a and 55a have substantially the same size and shape on a plane perpendicular to the Z direction. The driver IC applies a high potential (VDD potential) to the connection electrode 54a and a low potential (GND potential) to the connection electrode 55a through the COF wiring under the control of the control unit. The connection electrode 54a is held at a high potential, and the connection electrode 55a is held at a low potential.

The electrode layer 72 includes a high potential electrode 52, two low potential connection electrode portions 56, two floating electrode portions 64, and a floating electrode portion 65, as shown in FIG.

The high-potential electrode 52 includes a trunk 521 , a plurality of branch portions 523 branching from the trunk 521 , a plurality of individual portions 52 a branching from each branch portion 523 , and two high-potential receiving portions 522 .

The trunk 521 extends in the Y direction at one end (upper end in FIG. 8) of the piezoelectric layer 42 in the X direction. The plurality of branch portions 523 are arranged in the Y direction and extend from the stem 521 to the other side in the X direction (lower side in FIG. 8). Each individual portion 52a has a portion that overlaps the central portion of each pressure chamber 10 in the X direction in the Z direction and overlaps each drive electrode 51 in the Z direction (see FIG. 5). Each branch portion 523 connects a plurality of individual portions 52a. The stem 521 connects multiple branches 523 .

The X direction corresponds to the "second direction" of the invention, and the Y direction corresponds to the "third direction" of the invention. Also, the high potential corresponds to the "first potential" of the present invention, and the high potential electrode 52 corresponds to the "first potential electrode" of the present invention.

One of the two high potential receiving portions 522 is connected to one end (the left end in FIG. 8) of the stem 521 in the Y direction. The other of the two high-potential receiving portions 522 is connected to the other end (right end in FIG. 8) of the stem 521 in the Y direction. The two high potential receiving portions 522 extend in the X direction at one end (the left end in FIG. 8) and the other end (the right end in FIG. 8) of the piezoelectric layer 42 in the Y direction.

The two high potential receiving portions 522 overlap in the Z direction with the four connection electrodes 54a of the high potential connection electrode portion 54 (the four connection electrodes 54a arranged on one side in the X direction (upper side in FIG. 7)). ing. The two high potential receiving portions 522 are electrically connected to the four connection electrodes 54a through through holes formed in the piezoelectric layer 41, respectively, and receive high potential from the connection electrodes 54a.

The two low-potential connection electrode portions 56 are arranged at one end (the left end in FIG. 8) and the other end (the right end in FIG. 8) of the piezoelectric layer 42 in the Y direction, respectively. bottom). Each of the two low-potential connection electrode portions 56 is composed of two connection electrodes 56a and one connection electrode 56b that are spaced apart from each other in the X direction.

The two floating electrode portions 64 are arranged at one end (the left end in FIG. 8) and the other end (the right end in FIG. 8) of the piezoelectric layer 42 in the Y direction, respectively. is placed between Each of the two floating electrode portions 64 is composed of ten floating electrodes 64a spaced apart from each other in the X direction.

The floating electrode portion 65 is arranged at the other end (lower end in FIG. 8) of the piezoelectric layer 42 in the X direction. The floating electrode portion 65 is composed of a plurality of floating electrodes 65a spaced apart from each other in the Y direction. The floating electrodes 65a have substantially the same size and shape on a plane orthogonal to the Z direction, and are arranged at regular intervals in the Y direction.

The connection electrode 56a of the low-potential connection electrode portion 56 and the floating electrode 64a of the floating electrode portion 64 have substantially the same size and shape on a plane orthogonal to the Z direction, and one end of the piezoelectric layer 42 in the Y direction (Fig. 8) and the other end (right end in FIG. 8) are arranged at equal intervals in the X direction. On the other hand, the connection electrode 56b of the low-potential connection electrode portion 56 is longer in the X direction than the connection electrode 56a.

The two connection electrodes 56a are connected to the two connection electrodes 55a of the low-potential connection electrode portion 55 (the two connection electrodes 55a arranged third and fourth from the other side in the X direction (lower side in FIG. 7)) and the Z direction. overlaps with The two connection electrodes 56 a are electrically connected to the two connection electrodes 55 a through through holes formed in the piezoelectric layer 41 .

The connection electrode 56b overlaps the two connection electrodes 55a of the low-potential connection electrode portion 55 (the two connection electrodes 55a arranged at the other end in the X direction (lower end in FIG. 7)) in the Z direction. The connection electrode 56b is electrically connected to the two connection electrodes 55a through through holes formed in the piezoelectric layer 41. As shown in FIG.

The floating electrodes 64a and 65a of the floating electrode portions 64 and 65 are not electrically connected to any electrodes and are not given a potential.

The electrode layer 73 includes a low potential electrode 53, a high potential connection electrode portion 57, and two floating electrode portions 66, as shown in FIG.

The low-potential electrode 53 includes a trunk 531 , a plurality of branch portions 533 branched from the trunk 531 , a plurality of individual portions 53 a branched from each branch portion 533 , and two low-potential receiving portions 532 .

The stem 531 extends in the Y direction at the other end (lower end in FIG. 9) of the piezoelectric layer 43 in the X direction. The plurality of branch portions 533 are arranged in the Y direction and extend from the stem 531 to one side in the X direction (upper side in FIG. 9). Of the plurality of individual portions 53a, each individual portion 53a, except for the individual portions 53a located at one end and the other end in the X direction, straddles two pressure chambers 10 adjacent to each other in the X direction, and a portion overlapping in the Z direction (see FIG. 5). The individual portions 53a positioned at one end and the other end in the X direction have portions overlapping one pressure chamber 10 in the Z direction. In addition, each individual portion 53a has a portion overlapping each drive electrode 51 in the Z direction. Each branch portion 533 connects a plurality of individual portions 53a. The stem 531 connects a plurality of branch portions 533 .

The low potential corresponds to the "second potential" of the invention, and the low potential electrode 53 corresponds to the "second potential electrode" of the invention.

One of the two low-potential receiving portions 532 is connected to one end (the left end in FIG. 9) of the stem 531 in the Y direction. The other of the two low-potential receiving portions 532 is connected to the other end (right end in FIG. 9) of the stem 531 in the Y direction. The two low potential receiving portions 532 extend in the X direction at one end (the left end in FIG. 9) and the other end (the right end in FIG. 9) of the piezoelectric layer 43 in the Y direction, respectively.

The two low potential receiving portions 532 are respectively the four connection electrodes 55a of the low potential connection electrode portion 55 (the four connection electrodes 55a arranged on the other side in the X direction (lower side in FIG. 7)) and the low potential connection. It overlaps with the three connection electrodes 56a and 56b (see FIG. 8) of the electrode portion 56 in the Z direction. Each low potential receiving portion 532 is electrically connected to the three connection electrodes 56 a and 56 b of the low potential connection electrode portion 56 through through holes formed in the piezoelectric layer 42 . The three connection electrodes 56a and 56b are electrically connected to the four connection electrodes 55a of the low potential connection electrode section 55, respectively, as described above. Therefore, each low potential receiving portion 532 is electrically connected to the low potential connection electrode portion 55 (see FIG. 7) via the low potential connection electrode portion 56 (see FIG. 8). receives a low potential from

The high potential connection electrode portion 57 has a portion 57a extending in the Y direction and two portions 57b extending in the X direction. The portion 57a extends in the Y direction at one end (upper end in FIG. 9) of the piezoelectric layer 43 in the X direction. One of the two portions 57b is connected to one end (the left end in FIG. 9) of the portion 57a in the Y direction. The other of the two portions 57b is connected to the other Y-direction end (right end in FIG. 9) of the portion 57a.

The two portions 57b are the four connection electrodes 54a of the high-potential connection electrode portion 54 (the four connection electrodes 54a arranged on one side in the X direction (upper side in FIG. 7)) and the high-potential electrodes 52, respectively. It overlaps with the potential receiving portion 522 (see FIG. 8) in the Z direction. Each portion 57 b is electrically connected to each high potential receiving portion 522 through a through hole formed in the piezoelectric layer 42 . Each high potential receiving portion 522 is electrically connected to the four connection electrodes 54a of the high potential connection electrode portion 54 as described above. Therefore, the portion 57b is electrically connected to the high potential connection electrode portion 54 (see FIG. 7) via the high potential receiving portion 522 (see FIG. 8), and receives a high potential from the high potential connection electrode portion 54. receive.

The two floating electrode portions 66 are located between the portion 57b and the low potential receiving portion 532 in the X direction at one end (the left end in FIG. 9) and the other end (the right end in FIG. 9) of the piezoelectric layer 43 in the Y direction, respectively. are placed. Each of the two floating electrode portions 66 is composed of ten floating electrodes 66a spaced apart from each other in the X direction. The floating electrodes 66a have substantially the same size and shape on a plane orthogonal to the Z direction, and are arranged at equal intervals in the X direction.

Each floating electrode 66a of the floating electrode portion 66 is not electrically connected to any electrode and is not given a potential.

<Actuator part>
As shown in FIG. 5 , a portion of the piezoelectric layer 41 sandwiched between the drive electrode 51 and the individual portion 52 a of the high-potential electrode 52 in the Z direction is called a first active portion 91 . A portion of the piezoelectric layers 42 and 43 sandwiched between the drive electrode 51 and the individual portion 53 a of the low potential electrode 53 in the Z direction is called a second active portion 92 . The first active portion 91 is polarized primarily upward, and the second active portion 92 is polarized primarily downward. The piezoelectric actuator 22 has an actuator section 90 that is composed of one first active section 91 and two second active sections 92 sandwiching the first active section 91 in the X direction for each pressure chamber 10 .

Here, with reference to FIG. 6, the operation of the actuator section 90 corresponding to a certain nozzle 15 when ejecting ink from that nozzle 15 will be described.

Before the printer 1 starts the recording operation, a low potential (GND potential) is applied to each drive electrode 51 as shown in FIG. 6(a). At this time, due to the potential difference between the driving electrode 51 and the high-potential electrode 52, an upward electric field equal to the polarization direction is generated in the first active portion 91, and the first active portion 91 moves along the plane direction (X direction and Y direction). direction). As a result, the portion of the laminated body composed of the piezoelectric layers 41 to 43 that overlaps the pressure chamber 10 in the Z direction is flexed so as to protrude toward the pressure chamber 10 (downward). At this time, the volume of the pressure chamber 10 is smaller than when the laminate is flat.

When the printer 1 starts a recording operation and ejects ink from a certain nozzle 15, first, as shown in FIG. ) to a high potential (VDD potential). At this time, the potential difference between the drive electrode 51 and the high potential electrode 52 disappears, so that the contraction of the first active portion 91 is eliminated. On the other hand, a potential difference between the drive electrode 51 and the low potential electrode 53 causes a downward electric field equal to the polarization direction in the second active portion 92, causing the second active portion 92 to contract in the planar direction. However, the second active portion 92 suppresses crosstalk (a phenomenon in which pressure fluctuations due to deformation of the actuator portion 90 in a pressure chamber 10 are transmitted to another pressure chamber 10 adjacent to the pressure chamber 10 in the X direction). It has a function and hardly contributes to deformation of the actuator section 90 . In other words, at this time, the layered body does not bend so that the portion overlapping the pressure chamber 10 in the Z direction is convex in the direction away from the pressure chamber 10 (upward), and is in a flat state. As a result, the volume of the pressure chamber 10 becomes larger than that in FIG. 6(a).

After that, as shown in FIG. 6A, the potential of the drive electrode 51 corresponding to the nozzle 15 is switched from a high potential (VDD potential) to a low potential (GND potential). At this time, the potential difference between the drive electrode 51 and the low potential electrode 53 disappears, so that the contraction of the second active portion 92 is eliminated. On the other hand, the potential difference between the drive electrode 51 and the high-potential electrode 52 causes an upward electric field equal to the polarization direction in the first active portion 91, causing the first active portion 91 to contract in the planar direction. As a result, the portion of the laminate that overlaps the pressure chamber 10 in the Z direction bends so as to protrude toward the pressure chamber 10 (downward). At this time, the volume of the pressure chamber 10 is greatly reduced, so that a large pressure is applied to the ink inside the pressure chamber 10 and the ink is ejected from the nozzle 15 .

<Description of the present invention>
As shown in FIG. 9, among the plurality of branch portions 533 of the low potential electrode 53, the branch portion 533 positioned at one end in the Y direction (the left end in FIG. 9) The width is smaller than that of the branch portion 533 located at the center. For example, the width W1 of the branch portion 533 located at one end in the Y direction is 1/2 to 2/3 of the width W2 of the branch portion 533 located at the other end in the Y direction. Width W3 of branch portion 533 positioned at the other end in the Y direction (right end in FIG. 9) is larger than widths W1 and W2.

The width of each branch 533 is constant in the second direction (that is, from the proximal end 533a connected to the trunk 531 of the branch 533 to the distal end 533b).

Of the plurality of individual portions 53a projecting from the branch portion 533 located at one end in the Y direction (left end in FIG. 9), the individual portion (first individual portion) located on one side in the Y direction (left side in FIG. 9). The length P1 is longer than the length P2 of the individual portion (second individual portion) located on the other side in the Y direction (right side in FIG. 9).

Y The minimum distance L2 in the Y direction between the portion of the branch portion 533 located at the other end of the direction (the right end in FIG. 9) where the plurality of individual portions 53a are connected and the other end 22b of the piezoelectric actuator 22 in the Y direction. small.

Comparing the widths of the branch portions 533 (see FIG. 9) of the low potential electrode 53 and the branch portions 523 (see FIG. 8) of the high potential electrode 52, the width of each branch portion 533 is greater than the width of each branch portion 523. . The width W2 of the branch portion 533 positioned other than the ends in the Y direction (the center other than the left and right ends in FIG. 9) is the same as the width W2 of the branch portions positioned other than the ends in the Y direction (the center other than the left and right ends in FIG. 8). 523 width W5.

As shown in FIG. 8, among the plurality of branch portions 523 of the high-potential electrode 52, the branch portion 523 located at one end in the Y direction (the left end in FIG. 8) The width is smaller than that of the branch portion 523 located in the center. For example, the width W4 of the branch portion 523 positioned at one end in the Y direction is 1/2 to 2/3 of the width W5 of the branch portion 523 positioned at the other end in the Y direction.

<Manufacturing Method of Piezoelectric Actuator>
In the piezoelectric actuator 22, as shown in FIG. 10, electrode layers 71 to 73 are formed on the surfaces of the piezoelectric layers 41 to 43 (S1), and then the piezoelectric layers 41 to 43 are stacked and adhered to each other (S2). Manufactured by In S2, the piezoelectric layers 41 to 43 are laminated in the Z direction so that each of the individual portions 52a and 53a has a portion that overlaps with each drive electrode 51 in the Z direction.

In S1, as shown in FIG. 11, the electrode layers 71 to 73 are formed by screen printing using a squeegee 100. As shown in FIG. In this embodiment, screen printing is performed from the other side of the Y direction (the right side in FIGS. 7 to 9) to the one side (the left side in FIGS. 7 to 9).

For example, when forming the electrode layer 73, as shown in FIG. Then, the squeegee 100 is moved from the other side (right side in FIG. 11) toward one side (left side in FIG. 11) in the Y direction to form the low potential electrode 53 and the like by screen printing. At this time, the squeegee 100 moves while holding the electrode material (for example, silver, nickel, gold, etc.) 110 on the downstream side (left side in FIG. 11) in the printing direction of the screen printing. The electrode layer 73 including the low potential electrode 53 is formed by the material 110 entering the hole 101x.

Furthermore, at this time, bleeding A occurs due to the material 110 flowing into the electrode layer 73 downstream in the printing direction (to the left in FIG. 11). The bleeding A has, for example, a thickness of 0.1 μm or less and a length in the Y direction of 10 to 100 μm.

In the present embodiment, in consideration of the occurrence of bleeding A, among the plurality of branch portions 533 of the low-potential electrode 53, one end in the Y direction (FIG. 9), which is concerned about an increase in capacitance due to tensile stress during adhesion, is particularly concerned. The width W1 of the branch portion 533 positioned at the left end of the vertical direction) is made smaller than the width W2 of the branch portion 533 positioned at a position other than the ends in the Y direction (other than the left and right ends in FIG. 9, the center). Further, among the plurality of individual portions 53a projecting from the branch portion 533 located at one end in the Y direction, the individual portion (first individual portion) located on one side in the Y direction (left side in FIG. 9) has a length P1 of , and longer than the length P2 of the individual portion (second individual portion) located on the other side in the Y direction (the right side in FIG. 9).

Furthermore, in the present embodiment, not only the low potential electrode 53 but also the high potential electrode 52 have a width of the branch portion 523 located at one end (left end in FIG. W4 is made smaller than the width W5 of the branch portion 523 located outside the ends in the Y direction (the center other than the left and right ends in FIG. 8).

<Structure and effect of the present embodiment>
As described above, according to the present embodiment, at least one of the high-potential electrode 52 and the low-potential electrode 53 (both in this embodiment) is positioned at one end in the Y direction (left end in FIGS. 8 and 9). The width of the branch portions 523 and 533 located outside the ends in the Y direction (the center other than the left and right ends in FIGS. 8 and 9) is smaller than the width of the branch portions 523 and 533 located outside. When the high-potential electrode 52 and the low-potential electrode 53 are formed by screen printing along the Y-direction during the manufacture of the piezoelectric actuator 22, one end of the plurality of branch portions 533 of the low-potential electrode 53 in the Y-direction ( 9) is made smaller than the width W2 of the branch portion 533 positioned other than the ends in the Y direction (other than the left and right ends of FIG. 9, the center). Among the plurality of branch portions 523, the width W4 of the branch portion 523 positioned at one end in the Y direction (left end in FIG. 8) is positioned at a position other than the ends in the Y direction (other than the left and right ends in FIG. 8, the center). It is made smaller than the width W5 of the branch portion 523 . This suppresses an increase in capacitance due to bleeding A (see FIG. 11) with respect to the actuator section 90 located at one end in the Y direction (the left end in FIGS. 8 and 9). Therefore, in the actuator section 90 located at one end in the Y direction, the tensile stress at the time of bonding (resulting from the warping of the end of the piezoelectric actuator 22) causes an increase in capacitance, but the bleeding A causes an increase in capacitance. An increase in capacity becomes difficult to occur. In the actuator portions 90 positioned other than the ends in the Y direction, an increase in capacitance due to bleeding A occurs, but an increase in capacitance due to tensile stress during adhesion is difficult to occur. Thereby, the difference in capacitance between the actuator units 90 can be suppressed.

If there is a difference in capacitance between the actuator sections 90, the ejection performance will vary between the nozzles 15 corresponding to the actuator sections 90, and the recording quality may deteriorate. In this embodiment, the problem can be suppressed.

The width W2 of the branch portion 533 positioned other than the ends in the Y direction (the center other than the left and right ends in FIG. 9) is the same as the width W2 of the branch portions positioned other than the ends in the Y direction (the center other than the left and right ends in FIG. 8). 523 width W5. The larger the width, the more likely bleeding occurs and the more likely the capacitance increases. Therefore, by configuring at least the branch portion 533 of the low-potential electrode 53 having the larger width as described above, the effect of the spread A is suppressed, and the effect of suppressing the difference in capacitance between the actuator portions 90 is further enhanced. It can certainly be realized.

The thickness of the branch portion 533 of the low potential electrode 53 is greater than the thickness of the branch portion 523 of the high potential electrode 52 (see FIG. 4). The greater the thickness, the more likely bleeding occurs and the more likely the capacitance increases. Therefore, by configuring at least the branch portion 533 of the low-potential electrode 53 having the larger thickness as described above, the effect of the spread A is suppressed, and the effect of suppressing the difference in capacitance between the actuator portions 90 is further enhanced. It can certainly be realized.

Not only one of the high-potential electrode 52 and the low-potential electrode 53, but also both of the branch portions 523 and 533 located at one end in the Y direction (the left end in FIGS. 8 and 9) have widths other than the ends in the Y direction ( The width is smaller than the width of branch portions 523 and 533 located in the center (other than the left and right ends in FIGS. 8 and 9). As a result, in both the branch portion 523 of the high-potential electrode 52 and the branch portion 533 of the low-potential electrode 53, the effect of suppressing the bleeding A and suppressing the difference in capacitance between the actuator portions 90 can be realized more reliably. .

Y The minimum distance L2 in the Y direction between the portion of the branch portion 533 located at the other end of the direction (the right end in FIG. 9) where the plurality of individual portions 53a are connected and the other end 22b of the piezoelectric actuator 22 in the Y direction. small. The closer to the ends 22a and 22b of the piezoelectric actuator 22, the easier it is for warping to occur, and the easier it is for a local force to be applied during adhesion. Therefore, the actuator section 90 arranged near the one end 22a of the piezoelectric actuator 22, which has the smaller minimum interval L1, tends to increase the capacitance due to the tensile stress during bonding, and it is particularly necessary to suppress the capacitance. . Therefore, by reducing the width W1 of the branch portion 533 corresponding to the actuator portion 90, the increase in capacitance due to bleeding A is suppressed, and the effect of suppressing the difference in capacitance between the actuator portions 90 is more effective. can be practically realized.

A length P1 of an individual portion (first individual portion) located on one side in the Y direction (left side in FIG. 9) and an individual portion (second individual portion) located on the other side in the Y direction (right side in FIG. 9) are different from each other. When the piezoelectric actuator 22 is manufactured, the length P1 is made longer than the length P2 when the low potential electrode 53 is formed by screen printing from the other side to the one side in the Y direction. Accordingly, even when bleeding A occurs in the branch portion 533, an increase in the capacitance of the actuator portion 90 can be suppressed.

The width of the branch portion 533 located at one end in the Y direction (the left end in FIG. 9) is constant over the X direction. As a result, bleeding A can be suppressed over the entire X direction, and an increase in capacitance can be suppressed.

The width W1 of the branch portion 533 positioned at one end in the Y direction (the left end in FIG. 9) is 1/1/1/2 of the width W2 of the branch portion 533 positioned at the other end in the Y direction (the center other than the left and right ends in FIG. 9). 2 to 2/3. As a result, even when the thickness of the branch portion 533 is large, an increase in capacitance due to bleeding A can be reliably suppressed.

<Second embodiment>
Next, a piezoelectric actuator 222 according to a second embodiment of the invention will be described with reference to FIG.

In the first embodiment, the width of each branch 533 is constant over the second direction, whereas in the second embodiment, the width of each branch 533 gradually increases from the proximal end 533a toward the distal end 533b. relatively smaller. In each branch 533, the width of the distal end 533b is smaller than the width of the proximal end 533a. Specifically, in the branch portion 533 located at one end in the Y direction (the left end in FIG. 12), the width Wb of the tip 533b is smaller than the width Wa of the base 533a. In the branches 533 located at the ends other than the ends in the Y direction (the center other than the left and right ends in FIG. 12), the width Wb' of the tip 533b is smaller than the width Wa' of the base 533a. In the branch portion 533 located at the other end (the right end in FIG. 12) in the Y direction, the width Wb″ of the tip 533b is smaller than the width Wa″ of the base 533a.

This configuration is based on the fact that since the high-potential electrode 52 has a trunk (belt portion) 521 (see FIG. 8) extending in the Y direction, the piezoelectric actuator 222 is likely to warp in the vicinity of one end 222c in the X direction. . The trunk 521 of the high-potential electrode 52 is arranged such that the distance between the tip 533b of each branch 533 of the low-potential electrode 53 and one end of the piezoelectric actuator 22 in the X direction (the tip 533b of each branch 533 is 533 (one end shorter than the distance from the proximal end 533a) 222c. The tip 533b of the branch 533 is close to the one end 222c and is greatly affected by warping (that is, the capacitance is likely to increase due to tensile stress during bonding), so it is particularly necessary to suppress the capacitance. Therefore, by reducing the width of the tip 533b, the increase in capacitance due to bleeding A can be suppressed, and the effect of suppressing the difference in capacitance between the actuator portions 90 can be more effectively realized.

The second embodiment is the same as the first embodiment, except that the width of each branch 533 gradually decreases from the proximal end 533a toward the distal end 533b. For example, the width of the branch 533 positioned at one end in the Y direction (the left end in FIG. 12) is wider than the width of the branch 533 positioned at the other end in the Y direction (the center other than the left and right ends in FIG. 12). is small. At the time of manufacturing the piezoelectric actuator 222, when forming the low potential electrode 53 by screen printing along the Y direction, among the plurality of branch portions 533 of the low potential electrode 53, one end in the Y direction (the left end in FIG. 12) is The width of the branch portion 533 positioned is made smaller than the width W2 of the branch portion 533 positioned outside the ends in the Y direction (the center other than the left and right ends in FIG. 12). Screen printing is performed from the other side (right side in FIG. 12) to one side (left side in FIG. 12) in the Y direction.

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

In the second embodiment (see FIG. 12), the width of each branch portion 533 gradually decreases from the proximal end 533a toward the distal end 533b, but is not limited to this. For example, the portion near the tip 533b and the other portion may each have a constant width in the X direction, and the width of the portion near the tip 533b may be smaller than the width of the other portion.

In the above-described embodiment, in both the high-potential electrode 52 and the low-potential electrode 53, the width of the branch portions 523 and 533 located at one end in the Y direction (the left end in FIGS. 8 and 9) is The width is smaller than the width of the branch portions 523 and 533 located at the center (other than the left and right ends in FIGS. 8 and 9), but is not limited thereto. Only the branch 533 of the potential electrode 53 may have this configuration. For example, the low potential electrode 53 has a stem 531, a branch portion 533, and an individual portion 53a, while the high potential electrode 52 has the individual portion 52a but does not have the stem 521 and the branch portion 523. Only branch 533 may have the above configuration.

In the above-described embodiment, for example, in the low-potential electrode 53, only the width of the branch portion 533 located at one end in the Y direction (the left end in FIGS. 9 and 12) is reduced. , left and right ends in FIG. 12) is made smaller than the width of the branch portions 533 located at the ends other than the ends in the Y direction (the center other than the left and right ends in FIGS. 9 and 12). You may The same applies to the high potential electrode 52 (see FIG. 8).

In the above-described embodiments, the direction of screen printing is from the other side of the Y direction (right side in FIGS. 8, 9, and 12) to the one side (left side in FIGS. 8, 9, and 12). 8, 9, and 12) to the other (right in FIGS. 8, 9, and 12). In this case, the length P2 of the individual portion (second individual portion) located on the other side in the Y direction (right side in FIG. 9) is changed to the length P2 of the individual portion (first individual portion) located in one side in the Y direction (left side in FIG. 9) individual portion) is longer than the length P1.

In the above-described embodiment, the thickness of the low potential electrode 53 is greater than the thickness of the high potential electrode 52, but the present invention is not limited to this. good too.

The first potential is not limited to a high potential and the second potential is a low potential, and the reverse (that is, the first potential is a low potential and the second potential is a high potential) may be used. In this case, the high potential electrode 52 may be positioned in the bottom layer, and the low potential electrode 53 may be positioned in the middle layer.

Although the number of piezoelectric layers constituting the piezoelectric actuator is three in the above embodiment, it may be four or more. For example, in the above-described embodiments (see FIG. 4 and the like), another piezoelectric layer may be arranged between the piezoelectric layer 43 of the piezoelectric actuator 22 and the plate 31 of the channel unit 21 .

The present invention is not limited to printers, but can also be applied to facsimiles, copiers, multi-function machines, and the like. The present invention can also be applied to a liquid ejection apparatus used for purposes other than image recording (for example, a liquid ejection apparatus that ejects a conductive liquid onto a substrate to form a conductive pattern). Furthermore, the piezoelectric actuator according to the present invention can be applied to any device other than the liquid ejection device.

22; 222 piezoelectric actuator 41 piezoelectric layer (first piezoelectric layer)
42 piezoelectric layer (second piezoelectric layer)
43 piezoelectric layer (third piezoelectric layer)
51 drive electrode 52 high potential electrode (first potential electrode)
52a individual part 521 trunk (belt part)
523 branch 53 low potential electrode (second potential electrode)
53a individual portion 531 stem 533 branch portion 533a proximal end 533b distal end 71 electrode layer (first electrode layer)
72 electrode layer (second electrode layer)
73 electrode layer (third electrode layer)
90 Actuator section

Claims (11)

a first piezoelectric layer; a second piezoelectric layer laminated on the first piezoelectric layer in a first direction along the thickness direction of the first piezoelectric layer; a third piezoelectric layer laminated in the first direction and sandwiching the second piezoelectric layer between itself and the first piezoelectric layer; a first electrode layer disposed on the side surface; a second electrode layer disposed between the first piezoelectric layer and the second piezoelectric layer in the first direction; A piezoelectric actuator comprising a piezoelectric layer and a third electrode layer disposed between the third piezoelectric layer,
The first electrode layer includes a plurality of drive electrodes to which either a first potential or a second potential different from the first potential is selectively applied,
the second electrode layer includes a first potential electrode held at the first potential;
the third electrode layer includes a second potential electrode held at the second potential;
At least one of the first potential electrode and the second potential electrode includes a plurality of individual portions having portions that overlap each of the plurality of drive electrodes in the first direction, and a plurality of individual portions that extend in a second direction perpendicular to the first direction. a plurality of branch portions that extend and connect the plurality of individual portions; and a trunk that extends in a third direction orthogonal to the first direction and the second direction and connects the plurality of branch portions,
A piezoelectric actuator, wherein, among the plurality of branch portions, a branch portion positioned at one end in the third direction has a smaller width than a branch portion positioned other than the end portion in the third direction. each of the first potential electrode and the second potential electrode includes the plurality of individual portions, the plurality of branch portions, and the trunk;
Among the plurality of branch portions of one of the first potential electrode and the second potential electrode, the branch portion positioned other than the end portion in the third direction is the branch portion of the other of the first potential electrode and the second potential electrode. Among the plurality of branch portions in the above, the width is larger than the branch portions located other than the end portion in the third direction,
In at least one of the first potential electrode and the second potential electrode, among the plurality of branch portions, the branch portion positioned at one end in the third direction is a branch portion positioned other than the end in the third direction. 2. A piezoelectric actuator according to claim 1, characterized in that the width is less than . each of the first potential electrode and the second potential electrode includes the plurality of individual portions, the plurality of branch portions, and the trunk;
the plurality of branch portions on one of the first potential electrode and the second potential electrode are thicker than the plurality of branch portions on the other of the first potential electrode and the second potential electrode;
In at least one of the first potential electrode and the second potential electrode, among the plurality of branch portions, the branch portion positioned at one end in the third direction is a branch portion positioned other than the end in the third direction. 3. The piezoelectric actuator according to claim 1, wherein the width is smaller than . each of the first potential electrode and the second potential electrode includes the plurality of individual portions, the plurality of branch portions, and the trunk;
In each of the first potential electrode and the second potential electrode, among the plurality of branch portions, the branch portion positioned at one end in the third direction is more likely than the branch portion positioned other than the end in the third direction. 4. The piezoelectric actuator according to any one of claims 1 to 3, characterized in that the width is small. The minimum distance in the third direction between the portion where the plurality of individual portions are connected in the branch portion located at one end in the third direction among the plurality of branch portions and the one end of the piezoelectric actuator in the third direction. The distance between the portion where the plurality of individual portions of the branch portion located at the other end in the third direction among the plurality of branch portions are connected and the other end of the piezoelectric actuator in the third direction is the distance between the The piezoelectric actuator according to any one of claims 1 to 4, characterized in that it is smaller than the minimum spacing in the third direction. The plurality of individual parts connected to the branch part located at one end in the third direction,
a first individual portion positioned in one of the third directions with respect to the branch portion;
a second individual portion located on the other side of the third direction with respect to the branch portion;
The length of the first individual portion in the third direction and the length of the second individual portion in the third direction are different from each other, according to any one of claims 1 to 5. piezoelectric actuator. The piezoelectric actuator according to any one of claims 1 to 6, wherein the width of the branch portion positioned at one end in the third direction is constant over the second direction. The other of the first potential electrode and the second potential electrode is a strip extending in the third direction, and the plurality of strips on one of the first potential electrode and the second potential electrode in the second direction. Arranged between the tip of the branch and one end of the piezoelectric actuator in the second direction where the distance between the tips of the plurality of branches and the tip of the plurality of branches is shorter than the distance between the base ends of the plurality of branches. including a band that has been
In one of the first potential electrode and the second potential electrode, each of the plurality of branches has a width smaller at the distal end than at the proximal end. 10. The piezoelectric actuator according to claim 1. Claims 1 to 1, wherein the width of the branch portion positioned at one end in the third direction is 1/2 to 2/3 of the width of the branch portion positioned other than the end portion in the third direction. 9. The piezoelectric actuator according to any one of 8. a first piezoelectric layer; a second piezoelectric layer laminated on the first piezoelectric layer in a first direction along the thickness direction of the first piezoelectric layer; A method for manufacturing a piezoelectric actuator comprising: a third piezoelectric layer laminated in the first direction and sandwiching the second piezoelectric layer between the first piezoelectric layer and the first piezoelectric layer;
forming on the surface of the first piezoelectric layer a first electrode layer including a plurality of drive electrodes to which either a first potential or a second potential different from the first potential is selectively applied;
forming a second electrode layer including a first potential electrode held at the first potential on the surface of the second piezoelectric layer;
forming a third electrode layer including a second potential electrode held at the second potential on the surface of the third piezoelectric layer;
The first electrode layer is arranged on a surface of the first piezoelectric layer opposite to the second piezoelectric layer in the first direction, and the second electrode layer is arranged between the first piezoelectric layer and the second piezoelectric layer in the first direction. two piezoelectric layers, and such that the third electrode layer is disposed between the second piezoelectric layer and the third piezoelectric layer in the first direction; laminating the second piezoelectric layer and the third piezoelectric layer in the first direction;
In at least one of forming the second electrode layer and forming the third electrode layer, the plurality of individual portions and the plurality of individual portions extending in a second direction perpendicular to the first direction are formed. and a trunk extending in a third direction orthogonal to the first direction and the second direction and connecting the plurality of branch portions. forming at least one of the two potential electrodes;
When the first piezoelectric layer, the second piezoelectric layer, and the third piezoelectric layer are laminated in the first direction, the plurality of individual portions overlap each of the plurality of drive electrodes in the first direction. laminating the first piezoelectric layer, the second piezoelectric layer and the third piezoelectric layer in the first direction so as to have;
Further, in at least one of the formation of the second electrode layer and the formation of the third electrode layer, among the plurality of branch portions, the branch portion located at one end in the third direction At least one of the first potential electrode and the second potential electrode is formed by screen printing along the third direction so that the width is smaller than the width of the branch portions positioned other than the end portions in the three directions. A method of manufacturing a piezoelectric actuator, comprising: At least one of forming the second electrode layer and forming the third electrode layer,
Screen printing is performed from the other side to one side of the third direction,
The plurality of individual portions connected to the branch portion located at one end in the third direction are a first individual portion located on one side in the third direction with respect to the branch portion, and a second individual portion located in the other of the third directions, wherein the length of the first individual portion in the third direction is longer than the length of the second individual portion in the third direction, 11. The method of manufacturing a piezoelectric actuator according to claim 10, wherein at least one of said first potential electrode and said second potential electrode is formed.

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