JP2002036544A - Piezoelectric actuator in piezoelectric ink jet printer head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce warp deformation of the entire piezoelectric actuator 20 based on the alternating pattern layers of individual electrode 24 and common electrode 25 at the time of laminating piezoelectric sheets. SOLUTION: Piezoelectric sheets 22, 21b, 21d, 21f, 22 where an individual electrode 24 is formed on one wide face and piezoelectric sheets 21a, 21c, 21e, 21g where a common electrode 25 and a dummy individual electrode 26 are formed on one wide face are laminated alternately, a top sheet 23 is laminated on the surface thereof and surface electrodes 30, 31 are formed on the surface thereof. The common electrode 25 and the dummy individual electrode 26 are shifted alternately in the short side direction of the piezoelectric sheet for every other lamination such that the break 35 between the common electrode 25 and the dummy individual electrode 26 is located closely to one side edge thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate type piezoelectric actuator used for printing in a piezoelectric ink jet printer head, and more particularly, to a common electrode as a driving electrode for applying a driving voltage. It relates to the configuration of electrodes and individual electrodes.

[0002]

2. Description of the Related Art In the prior art on-demand type piezoelectric ink jet printer head, Japanese Patent Application No.
As described in the specification of Japanese Patent Application No. 72678, a cavity plate having a plurality of nozzles and pressure chambers for each of the nozzles, a planar individual electrode formed for each of the pressure chambers, and an adjacent electrode are provided. And a plate-type piezoelectric actuator laminated with a piezoelectric sheet (a green sheet made of a ceramic material) sandwiched by common electrodes common to a plurality of pressure chambers, and the piezoelectric actuator is attached to the cavity plate by the piezoelectric actuator. A structure in which individual electrodes are stacked so as to correspond to pressure chambers is disclosed. In that case, a plurality of nozzles are arranged in a row at the center of the short side (width direction) in parallel with the long side edge of the cavity plate, and the corresponding pressure chambers are formed in the cavity plate. On both sides of the center line in the width direction, the cavity plates were arranged in a row in the long side direction parallel to the short side edges of the cavity plate.

Accordingly, as shown in FIGS. 9 and 10, piezoelectric sheets 103a, 103c,
103e, 103g and piezoelectric sheets 103b, 103d, 103f, 103h having the common electrode 102 are alternately laminated. The individual electrodes 101 of the piezoelectric actuator 100 are arranged in a row in the long side direction parallel to the short side edge of the piezoelectric sheet on both sides of the center line in the width direction (short side) of the piezoelectric sheet. And the common electrode 10
2 straddles the center line in the width direction (short side) of the piezoelectric sheet,
In addition, the piezoelectric sheet is formed in a substantially rectangular shape in a plan view at a portion that straddles all the pressure chambers on both sides and excludes a portion near the pair of long sides of the piezoelectric sheet. Further, on the surfaces of the piezoelectric sheets 103b, 103d, 103f, and 103h having the common electrodes 102, the dummy individual electrodes 104 are formed by forming cuts (intervals) 109 with the side edges of the common electrodes 102 in the longitudinal direction. It was formed at the same vertical position as 101. The dummy individual electrode 104 does not contribute to the deformation of the piezoelectric actuator, but reduces the change in the partial thickness when the piezoelectric sheet and the electrode are stacked.
Note that a terminal portion of a flexible flat cable (not shown) for applying a signal from an external circuit to the corresponding individual electrode 101 and common electrode 102 is provided on the surface of the top sheet 105 which is the uppermost piezoelectric sheet. Surface electrodes 106 and 107 to be connected are formed, and the individual electrodes 101 and the dummy individual electrodes 104 extending in the thickness direction of the piezoelectric sheet and electrically connected to the dummy individual electrodes 104 at the same vertical position are formed on the long side surfaces of the pair of piezoelectric sheets. Side electrode 108 is formed (see FIG. 10).

[0004]

By the way, individual electrodes and common electrodes are printed and formed in a thin layer on a wide surface of a piezoelectric sheet (green sheet) with a conductive paste, and the piezoelectric sheets are laminated and pressed. When firing, in the vertical direction of the lamination, in principle, the portion of the green sheet alone hardly shrinks most, and the portion with the electrode layer shrinks more.

For example, as shown in FIG. 10, in a state in which nine piezoelectric sheets 103a to 103h and 105 are stacked, for example, the position of a break 109 between the pattern of the dummy individual electrode 104 and the pattern of the common electrode 102 is When the dimension L1 from the long side edge of the piezoelectric sheet 103 is made the same, the center line of the thickness of the piezoelectric actuator 100 (the fifth piezoelectric sheet 1
When viewed from the vertical direction from the center line (thickness direction 03e in the thickness direction 03e) 110, the bias of the film density of the electrode portion (that is, the conductive material) is closer to the center line side in the upper half, and the bias is centered in the lower half side. You can see that it is far from the line. For this reason, the contraction at a portion distant from the center line causes the entire piezoelectric actuator to warp. In the piezoelectric actuator 100 in FIG. 10, the layers on both sides sandwiching the cut 109 are sharply downward (the number of curved portions is small). ) Bending such as bending occurs.

[0006] If such a sharp bend or warpage is too large, a gap is formed in the bent portion when one side of the wide surface of the piezoelectric actuator is bonded and fixed to the wide surface of the cavity plate with an adhesive. For example, there is a problem in that satisfactory fixing cannot be performed, and a defect of ink leakage occurs.

An object of the present invention is to provide a plate type piezoelectric actuator which solves such a problem.

[0008]

In order to achieve this technical object, a piezoelectric actuator in a piezoelectric ink jet printer head according to the first aspect of the present invention comprises a plurality of nozzles and a pressure chamber for each nozzle. A cavity plate provided in a row in one direction, and a piezoelectric actuator formed by laminating a piezoelectric sheet having a pattern of drive electrodes to be driven for each of the pressure chambers formed on the surface thereof. In a cavity type, in a piezoelectric ink jet printer head in which each drive electrode in the piezoelectric actuator is laminated so as to correspond to each pressure chamber, a cut in the pattern of the drive electrode formed on the surface of each piezoelectric sheet is For every other piezoelectric sheet to be laminated, a second direction orthogonal to the first direction of the piezoelectric sheet It is obtained by appropriately shifted disposed direction.

According to a second aspect of the present invention, in the piezoelectric actuator of the piezoelectric ink jet printer head according to the first aspect, the individual electrodes corresponding to the respective pressure chambers of the drive electrodes are arranged in the second direction. A piezoelectric sheet patterned so as to extend along the piezoelectric sheet, and a piezoelectric sheet patterned so that the common electrode and the dummy individual electrode of the drive electrodes extend along the second direction through cuts. Are alternately arranged for every other layer so that the end portions of the individual electrodes and the dummy individual electrodes are located on one side edge side parallel to the first direction of the piezoelectric sheet.

[0010] Further, the invention described in claim 3 is based on claim 2.
The piezoelectric actuator in the piezoelectric inkjet printer head according to the above, wherein the pattern of the common electrode is disposed on the center side of the piezoelectric sheet in the second direction, and the pattern of the individual electrode and the dummy individual electrode is the second pattern of the piezoelectric sheet. In the direction of the left and right sides.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1, 7, and 8 show a piezoelectric inkjet printer head according to an embodiment of the present invention. In these figures, on the upper surface of a plate type piezoelectric actuator 20 laminated on a metal plate cavity plate 10, for connection with an external device,
The flexible flat cable 40 is overlapped and bonded with an adhesive, and ink is ejected downward from a nozzle opened on the lower surface side of the lowermost cavity plate 10.

The cavity plate 10 is configured as shown in FIGS. That is, it has a structure in which five thin metal plates of a nozzle plate 11, two manifold plates 12, a spacer plate 13, and a base plate 14 are laminated. The nozzle plate 11
The nozzles 15 for ejecting ink having a small diameter are provided in a staggered arrangement of two rows along a first direction (long side direction) of the nozzle plate 11. That is, two reference lines 11 parallel to the first direction of the nozzle plate 11.
Along the lines a and 11b, a large number of nozzles 15 are formed in a staggered arrangement at intervals of a minute pitch P. The two manifold plates 12 have ink passages 12a, 1
2b are drilled so as to extend along both sides of the row of nozzles 15. However, the ink passage 1 in the lower manifold plate 12 facing the nozzle plate 11
The recess 2b is formed to be open only on the upper side of the manifold plate 12 (see FIG. 4). The ink passages 12a and 12b are configured to be sealed by stacking the spacer plate 13 on the upper manifold plate 12. The base plate 14 is provided with a large number of narrow pressure chambers 16 extending in a second direction (short side direction) orthogonal to a center line along the long side (the first direction). Have been. And, a longitudinal reference line 14 which is parallel on both left and right sides of the center line.
When a and 14b are set, the tip 16a of the pressure chamber 16 on the left side of the center line is located on the left longitudinal reference line 14a, and the tip 16a of the pressure chamber 16 on the right side of the longitudinal center line is located on the right side. And the front ends 16a of the left and right pressure chambers 16 are alternately arranged, so that the pressure chambers 16 on the left and right sides are alternately arranged so as to extend in opposite directions to every other one. It will be.

The tip 16a of each pressure chamber 16 is connected to the staggered nozzles 15 of the nozzle plate 11.
Are connected to the spacer plate 13 and the both manifold plates 12 through small-diameter through holes 17 also formed in a staggered arrangement. On the other hand, the other end 16 b of each of the pressure chambers 16 is connected to the ink passages 12 in the manifold plates 12 through through holes 18 formed in both right and left portions of the spacer plate 13.
a, 12b. The other end 16b is
As shown in FIG. 4, the recess is formed so as to open only on the lower surface side of the base plate 14. Also,
A filter 29 for removing dust in ink supplied from an ink tank above the supply hole 19a is provided on an upper surface of a supply hole 19a formed at one end of the uppermost base plate.

Thus, the base plate 14
And a supply hole 19 formed at one end of the spacer plate 13.
The ink flowing into the ink passages 12a and 12b from the ink passages 12a and 12b is distributed from the ink passages 12a to the pressure chambers 16 through the through holes 18 and then from the pressure chambers 16 to the ink passages 12a and 12b. The configuration is such that the gas reaches the nozzle 15 corresponding to the pressure chamber 16 through the through hole 17.

On the other hand, as shown in FIGS. 5 and 6, nine piezoelectric sheets 21a, 2
1b, 21c, 21d, 21e, 21f, 21g, 2
2 and 23 are stacked, and the uppermost surface (wide surface) of the lowermost piezoelectric sheet 22 and the odd-numbered piezoelectric sheets 21b, 21d, and 21f counted upward from the piezoelectric sheet 22 is formed.
In each of the pressure plates 16 in the cavity plate 10, narrow individual electrodes 24 are formed in a row along a first direction (long side direction).
Extends in the second direction orthogonal to the first direction to the vicinity of the long edge of each piezoelectric sheet.

The even numbered piezoelectric sheets 21a, 21 from the bottom
On the upper surfaces (wide surfaces) of c, 21e, and 21g, a common electrode 25 common to the plurality of pressure chambers 16 is formed.

In the embodiment, as can be understood from FIGS. 4 and 5, the width dimension of each of the individual electrodes 24 is set so as to cover the wide portion of the corresponding pressure chamber 16 in plan view.

On the other hand, the pressure chambers 16 are arranged in two rows along the first direction (long side) at the center of the short side of the base plate 14, so that the common electrodes 25 are formed.
The piezoelectric sheets 21 a, 21 c, 21 e, and 2 of even-numbered stages are formed so as to integrally cover the two rows of pressure chambers 16.
In the center of the short side direction of 1 g, it is formed in a substantially rectangular shape in plan view extending along the long side, and near the edge of the short side of the pair of the even-numbered piezoelectric sheets 21 a, 21 c, 21 e, and 21 g. Drawers 25a, 25a extending over substantially the entire length of the edge are integrally formed.

The even-numbered piezoelectric sheets 21
The same vertical position (corresponding position) as each of the individual electrodes 24 is provided on the surface near the long edge of the pair of a, 21c, 21e, and 21g where the common electrode 25 is not formed. Then, a dummy individual electrode 26 having the same width and a short length as the individual electrode 24 is formed. In this case, as shown in FIGS. 5 and 6, the end of each dummy individual electrode 26 has an appropriate gap dimension (A1) with respect to the side edge of the common electrode 25 in the first direction (along the long side). ), So that there is a cut 35. Moreover, the length of every other layer of the dummy individual electrode 26 is set to be longer or shorter as L2 and L3 (<L2), and the pattern of the pattern between the end of the dummy individual electrode 26 and the side edge of the common electrode 25 is set. The position of the cut 35 is set every other layer of the piezoelectric sheet in the second direction (short side direction) of the piezoelectric sheet.
It shifts.

In the embodiment, the length L2 of the dummy individual electrode 26 in the second layer (piezoelectric sheet 21a) and the sixth layer (piezoelectric sheet 21e) from the fourth layer (piezoelectric sheet 21c) The length is set to be longer by the gap dimension A1 than the length L3 of the dummy individual electrode 26 in the eighth layer (piezoelectric sheet 21g).

With this configuration, the width of the pattern cut 35 between the end of the dummy individual electrode 26 and the side edge of the common electrode 25 in the second direction (width direction) of the entire piezoelectric actuator 20 is reduced. 2 × A1 and the piezoelectric actuators 2 at the 35 cuts
Since the deviation of the density of the electrode layer in the thickness direction as a whole in the second direction is reduced, the piezoelectric actuator 20 after firing in the subsequent step is warped in the width direction (second direction) (the cut 35). The amount of deformation is small, and the warpage is not bent at a steep angle.
Can be gently curved with a large radius. As a result, the piezoelectric actuator 20 is moved to the cavity plate 1.
When adhesively fixed to 0, the gap (space) at the adhesive surface
This has the effect of preventing defects such as ink leakage in a state where a product as an ink jet is not generated. In the bonding step, the bonding pressure for pressing the piezoelectric actuator 20 and the cavity plate 10 can be reduced so that the wide surface (bonding surface) becomes flat.

On the other hand, the lowermost piezoelectric sheet 22 and the odd-numbered piezoelectric sheets 21b, 21d, 2
1f, the lead-out portions 25a,
A dummy common electrode 27 is formed at a position corresponding to 25a (the same vertical position, near the edge of the short side of the pair of piezoelectric sheets).

On the upper surface of the uppermost top sheet 23, a surface electrode 30 for each of the individual electrodes 24 and a surface electrode 31 for the common electrode 25 are formed along an edge of a long side thereof. Is provided.

Further, except for the lowermost piezoelectric sheet 22, all the other piezoelectric sheets 21a, 21b, 21c,
21d, 21e, 21f, 21g and the top sheet 23, the surface electrodes 30 and the individual electrodes 24 and the dummy individual electrodes 26 at the corresponding positions (the same vertical position) are provided.
Are formed so as to communicate with each other. Similarly, the at least one surface electrode 31 (in the embodiment, the surface electrodes 3 at the four corners of the top sheet 23)
1) and a through-hole 33 is formed so that the common electrode 25 at the corresponding position (the same vertical position) or the lead portion 25a thereof communicates with each other.
The individual electrodes 24 of each layer and the surface electrode 30 at a position corresponding to the individual electrodes 24 are interposed via the conductive material filled in the inside 2 and 33.
Are electrically connected, and similarly, the common electrodes 25 of each layer are electrically connected to the surface electrode 31 at a position corresponding to the common electrodes 25.

The above-structured piezoelectric actuator 20
Is manufactured by the method described below. That is, the piezoelectric sheet 21 of the one piezoelectric actuator 20
b, 21d, 21f, and 22 are arranged in a matrix and integrated into a matrix, and a plurality of individual electrodes 24 and a discarded pattern are formed on each piezoelectric sheet on the surface of a first material sheet (ceramic green sheet). A through-hole 32 is formed in advance corresponding to the position where the dummy common electrode 27 as an electrode is provided. Similarly, the piezoelectric sheets 21a, 21
On the surface of a second material sheet (ceramic green sheet) in which a plurality of c, 21e, and 21g are arranged in a matrix and integrated, a plurality of common electrodes 25 and a discarded pattern electrode are provided at each piezoelectric sheet. Corresponding to the position where the dummy individual electrode 26 is provided.
Drill 3 Further, as described above, the top sheet 2
In the surface of a third material sheet (ceramic green sheet) obtained by arranging a plurality of surface electrodes 30 in a matrix and integrating them, a plurality of surface electrodes 30,
Through holes 32 and 33 are formed at positions where the 31 is provided.

Then, each of the piezoelectric sheets 21b, 21d, 2
The individual electrodes 24 and the dummy common electrodes 27 are provided on the surfaces of 1 f and 22, the common electrodes 25 and the dummy individual electrodes 26 are provided on the surfaces of the piezoelectric sheets 21 a, 21 c, 21 e and 21 g, and the surface electrodes 30 and 31 are provided on the surface of the top sheet 23. When the portions are respectively formed by screen printing of a conductive paste, the through holes 32 and 33 penetrate the upper and lower wide surfaces of the first and second material sheets. Also, the conductive paste penetrates, and through each of the through holes 32 and 33, the upper and lower surfaces of the sheet can conduct electricity at each electrode portion. Next, after drying each green sheet, it is laminated and then integrated by pressing in the laminating direction to form one laminated body. Then, it is fired.

In this manner, the plurality of piezoelectric sheets 21 and the top sheet which are vertically stacked are electrically connected to the individual electrodes 24 and the dummy individual electrodes 26 at the same position in the vertical direction, and to the location of the surface electrode 30. Similarly, a plurality of upper and lower common electrodes 25 and dummy common electrodes 27 are electrically connected to the location of the surface electrode 31 (see FIG. 6).

The plate-type piezoelectric actuator 20 having such a structure is provided with the cavity plate 1.
0, the individual electrodes 24 of the piezoelectric actuator 20 are stacked and fixed so as to correspond to each of the pressure chambers 16 of the cavity plate 10 (see FIGS. 1 and 7). The flexible flat cable 40 is overlaid and pressed on the upper surface of the piezoelectric actuator 20, so that various wiring patterns (not shown) of the flexible flat cable 40 are applied to the surface electrodes 30, 31. Electrically connected to

In this configuration, of the individual electrodes 24 in the piezoelectric actuator 20, any of the individual electrodes 2
4 and the common electrode 25, a voltage is applied to the individual electrodes 24 of the piezoelectric sheets 21 and 22 to generate a distortion in the stacking direction due to the piezoelectric force. By reducing the internal volume of the pressure chamber 16 corresponding to each individual electrode 24, the pressure chamber 16
The ink inside is ejected in a droplet form from the nozzle 15 to perform predetermined printing (see FIG. 8).

In the piezoelectric actuator 20 having the above-described configuration, the individual electrodes 24 formed on the surface of each piezoelectric sheet through the through holes 32 and 33 penetrating the wide surface of the stacked piezoelectric sheets in the thickness direction, and the like. Common electrode 25
Can be electrically connected to each other and can also be electrically connected to the surface electrodes 30, 31 formed on the surface of the top sheet 23.
As compared with the case where the side electrodes are formed so that the individual electrodes 24 and the common electrodes 25 are electrically connected on the outer peripheral side surface in the thickness direction of 0, the piezoelectric actuator 20 is being manufactured, During assembling, there is an effect that the loss of the conductive portions between the individual electrodes 24 and between the common electrodes 25 due to the contact of the handler or the jig is eliminated.

Further, since the through holes 32 and 33 are not formed in the piezoelectric sheet 22 which is the contact surface between the piezoelectric actuator 20 and the cavity plate 10, if the cavity plate 10 is made of a conductive material (for example, (42% nickel alloy steel or the like), there is no possibility that the lowermost individual electrode 24 or the common electrode 25 will make electrical contact with the surface of the cavity plate 10. Further, since the through holes 32 and 33 do not exist in the piezoelectric sheet 22 adjacent to the cavity plate 10, even if the individual electrode 24 or the common electrode 25 is located at a position vertically overlapping the pressure chamber 16, No electrical short circuit occurs with the aqueous ink.

As a result, there is also an effect that the installation positions of the through holes 32 and 33 in the piezoelectric actuator 20 are not restricted and the degree of freedom in design is improved.

The individual electrodes 24 and the common electrodes 25 are formed on every other layer of the piezoelectric sheet 21.
As in the present embodiment, a dummy individual electrode 26 is formed on the piezoelectric sheet between the upper and lower individual electrodes 24, and a dummy common electrode 27 is formed on the piezoelectric sheet between the upper and lower common electrodes 25. The through hole 32 and the common electrode 25 which connect the electrode 26 and the individual electrode 24
And the dummy common electrode 27 are connected to each other, so that the vertical individual electrodes 24 or the common electrodes 25 are electrically connected to each other in the dummy individual electrode 26 or the dummy common electrode 27. This has a remarkable effect that it can be surely performed through the holes 32 and 33.

In the case where the dummy individual electrode 26 and the dummy common electrode 27 are not provided, unevenness occurs when the piezoelectric sheets are stacked, but the thickness change can be reduced due to the presence of the two electrodes 26 and 27.

In the embodiment, the thickness of one piezoelectric sheet is 30 μm, and the formation of the individual electrode 24, the common electrode 25 and the surface electrodes 30, 31 (the thickness of the electrode layer is approximately 5 μm).
The conductive material can penetrate (fill) into the through holes 32 and 33 by the application of the conductive material at the time m). When the thickness of one piezoelectric sheet is large, it is ensured that the conductive material enters (fills) into the through holes by suctioning air from the back side of the coating surface after the application of the electrode (conductive) material. be able to.

Further, the laminated body of the piezoelectric actuator is immersed in a plating solution, and in this state, each of the surface electrodes 30,
A metal plating layer may be formed on the surface of each of the surface electrodes 30 and 31 by applying an electric current to the surface electrode 31 through a narrow electrode pattern to perform electroplating. The metal plating layer is, for example, formed by forming a gold plating layer on a nickel plating layer as a base. By forming the metal plating layer, the surface electrodes 30, 31 of each wiring pattern in the flexible flat cable 40 are formed. Can greatly improve the electrical bondability to the substrate.

In the present invention, the order of lamination of the layers of the individual electrodes 24 and the layers of the common electrodes 25 is such that the lowermost piezoelectric sheet having the common electrodes 25 faces the base sheet 14 in the cavity sheet 10. Needless to say, the present invention can also be applied to a modified one, and, instead of the through hole, a side surface of the piezoelectric actuator laminate (a side surface orthogonal to the wide surface on which the surface electrodes 30 and 31 are formed).
The surface electrode 30 electrically connects the individual electrodes 24 and the dummy individual electrodes 26 via the side electrode, while the surface electrode 31 is electrically connected to the common via another side electrode via the side electrode. The present invention may be applied to a configuration in which the electrodes 25 and the dummy common electrodes 27 are electrically connected. In this case, a concave groove for exposing at least each of the drive electrodes (common electrode, individual electrode, etc.) is provided on a side surface of the piezoelectric actuator orthogonal to both front and rear surfaces, and the drive electrode is electrically connected to the concave electrode in the concave groove. A side electrode which is electrically conductive may be formed.

Further, the present invention can be applied to a case where the first direction is a direction along the short side of the piezoelectric actuator 20 and the second direction is a direction along the long side.

[0039]

As described above, according to the first aspect of the present invention,
The piezoelectric actuator in the piezoelectric ink-jet printer head according to the aspect of the present invention comprises a plurality of nozzles and a cavity plate having pressure chambers for each of the nozzles arranged in a row in a first direction. And a piezoelectric actuator formed by laminating a piezoelectric sheet having a pattern of drive electrodes to be formed on the surface thereof.The piezoelectric actuator is provided on the cavity plate such that each drive electrode of the piezoelectric actuator corresponds to each pressure chamber. In the piezoelectric type ink jet printer head formed by laminating, the break of the pattern of the drive electrode formed on the surface of each piezoelectric sheet is perpendicular to the first direction of the piezoelectric sheet every other piezoelectric sheet to be laminated. In the second direction.

With this configuration, the width of the cut of the drive electrode pattern in the piezoelectric actuator as a whole is shifted in the second direction, and the density of the electrode layer in the thickness direction of the piezoelectric actuator as a whole at the cut location is reduced. 2
Therefore, the amount of warpage of the piezoelectric actuator in the second direction after firing in the subsequent step is small and can be gently curved. As a result, when the piezoelectric actuator is bonded and fixed to the cavity plate, there is no gap (space) in the bonding surface, and the effect of preventing ink leakage in a state of a product as an inkjet can be prevented. Play. In the bonding step, a wide surface (bonding surface) between the piezoelectric actuator and the cavity plate is flattened.
This has the effect that the bonding pressure for pressing both can be reduced.

According to a second aspect of the present invention, in the piezoelectric actuator in the piezoelectric ink jet printer head according to the first aspect, the individual electrodes corresponding to the respective pressure chambers of the drive electrodes are arranged in the second direction. A piezoelectric sheet patterned so as to extend along the piezoelectric sheet, and a piezoelectric sheet patterned so that the common electrode and the dummy individual electrode of the drive electrodes extend along the second direction through cuts. Are alternately arranged for every other layer so that the end portions of the individual electrodes and the dummy individual electrodes are located on one side edge side parallel to the first direction of the piezoelectric sheet.

Therefore, the presence of the dummy individual electrodes can reduce the change in the thickness when the piezoelectric sheets are stacked, while shifting the cuts as described above allows
The gap in the density of the electrode layers can be reduced, and the same effect as that of the first aspect can be obtained.

The invention described in claim 3 is the same as that in claim 2
The piezoelectric actuator in the piezoelectric inkjet printer head according to the above, wherein the pattern of the common electrode is disposed on the center side of the piezoelectric sheet in the second direction, and the pattern of the individual electrode and the dummy individual electrode is the second pattern of the piezoelectric sheet. In the direction of the left and right sides. With this configuration, in the piezoelectric actuator having two rows of individual electrodes, the warpage deformation in the second direction occurs at the portions of the piezoelectric sheet near the left and right side edges in the second direction, but the deformation amount is small. Thus, the same effects as those of the first and second aspects of the invention can be obtained.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a piezoelectric inkjet printer head according to an embodiment of the present invention.

FIG. 2 is an enlarged perspective view showing one end of a cavity plate and a piezoelectric actuator.

FIG. 3 is an exploded perspective view of a cavity plate.

FIG. 4 is a partially enlarged perspective view of a cavity plate.

FIG. 5 is an exploded perspective view of the piezoelectric actuator.

FIG. 6 is a partially enlarged side sectional view of a piezoelectric actuator cut at a through hole.

FIG. 7 is an enlarged sectional view taken along line VII-VII of FIG. 1;

FIG. 8 is an enlarged sectional view showing a state in which a flexible flat cable, a cavity plate, and a piezoelectric actuator are stacked.

FIG. 9 is an exploded perspective view showing a state of a pattern of an individual electrode, a common electrode, and a dummy individual electrode in a conventional piezoelectric actuator.

FIG. 10 is an enlarged sectional view taken along line XX in FIG. 9;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Cavity plate 11 Nozzle plate 12 Manifold plate 13 Spacer plate 14 Base plate 15 Nozzle 16 Pressure chamber 20 Piezoelectric actuator 21a, 21b, 21c, 21d, 21e, 21f, 2
1g, 22 Piezoelectric sheet 23 Top sheet 24 Individual electrode 25 Common electrode 26 Dummy individual electrode 27 Dummy common electrode 30, 31 Surface electrode 32, 33 Through hole 35 Cut 40 Flexible flat cable

Claims (3)

[Claims] 1. A cavity plate having a plurality of nozzles and pressure chambers for each nozzle arranged in a row in a first direction, and a pattern of a drive electrode for driving each pressure chamber are formed on the surface. A piezoelectric actuator formed by laminating piezoelectric sheets, wherein the piezoelectric actuator is formed by laminating the piezoelectric actuator on the cavity plate so that each drive electrode of the piezoelectric actuator corresponds to each pressure chamber. The breaks in the pattern of the drive electrodes formed on the surface of each of the piezoelectric sheets are appropriately shifted in the second direction orthogonal to the first direction of the piezoelectric sheets every other one of the stacked piezoelectric sheets. A piezoelectric actuator in a piezoelectric inkjet printer head. 2. A piezoelectric sheet in which individual electrodes corresponding to respective pressure chambers of the driving electrodes are patterned so as to extend along the second direction, and a common electrode and a dummy individual of the driving electrodes. A piezoelectric sheet having electrodes patterned in such a manner as to extend along the second direction through a cut line, wherein one end of the individual electrode and the dummy individual electrode is parallel to the first direction of the piezoelectric sheet; 2. The piezoelectric actuator according to claim 1, wherein the piezoelectric actuator is arranged alternately every other layer so as to be located on the edge side. 3. The pattern of the common electrode is arranged on the center side of the piezoelectric sheet in the second direction, and the patterns of the individual electrodes and the dummy individual electrodes are located on the left and right side edges of the piezoelectric sheet in the second direction. 3. The piezoelectric actuator according to claim 2, wherein the piezoelectric actuator is disposed at a position corresponding to the position of the piezoelectric actuator.