JP2002240278A - Ink jet printer head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet printer head in which the position of the inner electrode in a piezoelectric actuator is grasped externally and a cavity plate can be combined with the piezoelectric actuator depending on the position of the inner electrode. SOLUTION: A piezoelectric actuator 20 is formed by laying a plurality of inner electrodes and piezoelectric sheets in layers wherein the inner electrodes are interconnected electrically through holes 36 made through the piezoelectric sheets in the laying direction and a conductive material filling the through holes 36. Position of the inner electrode is grasped by at least one inner electrode 31Xa out of the plurality of inner electrodes extending up to the edge of the piezoelectric sheet, and then the piezoelectric actuator 20 is placed upon a cavity plate 10 such that the inner electrode corresponds to the pressure chamber 16 of the cavity plate 10, thus constituting an ink jet printer head.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer head, and more particularly to a method of combining a cavity plate and a piezoelectric actuator in accordance with the position of an internal electrode of a piezoelectric actuator by grasping the position of the internal electrode from the outside. The present invention relates to a possible ink jet printer head.

[0002]

2. Description of the Related Art An on-demand type piezoelectric ink jet printer head according to the prior art includes a cavity plate having a plurality of nozzles and a pressure chamber for each of the nozzles, and a planar individual plate formed for each of the pressure chambers. A plate-type piezoelectric actuator is formed by laminating a piezoelectric sheet (a green sheet made of a ceramic material) with an electrode and a common electrode common to a plurality of adjacent pressure chambers. Each individual electrode in the actuator is configured to overlap each other so as to correspond to each pressure chamber.

[0003] The piezoelectric actuator in the piezoelectric ink jet printer head thus configured is
The end of each of the individual electrodes extends to the edge of the piezoelectric sheet and is exposed, and on the side in the stacking direction, at least a side electrode electrically connected to the exposed end of each of the individual electrodes is formed by vacuum evaporation of metal. Alternatively, the electrodes are formed by sputtering, application of a conductive paste, or the like, and the individual electrodes are connected to the outside through the respective side electrodes.

When the individual electrodes of the piezoelectric actuator correspond to the pressure chambers of the cavity plate, the ends of the individual electrodes are invisible because they are covered by side electrodes. When the side electrode is formed, a slight displacement is unavoidable, and cannot be used as an assembly mark for associating the individual electrode with the pressure chamber. Therefore, a notch is provided between the ends of the individual electrodes extending to the edge of the piezoelectric sheet, and the notch is assembled with the piezoelectric actuator and the cavity plate. For the mark.

[0005] However, since the arrangement interval of the individual electrodes is small, the width of the notch becomes considerably small.
Recognition becomes difficult, the accuracy of assembly work deteriorates, and the so-called product yield deteriorates.

Therefore, individual electrodes provided on the piezoelectric sheet are arranged as shown in FIG. 9 to secure a space for providing an assembly mark. FIG. 9 is a view showing an arrangement pattern of individual electrodes in a conventional piezoelectric sheet. Specifically, a notch 53 having a predetermined width is disposed at the center of the longitudinal edge of the piezoelectric sheet 50, and the end 51 a of the individual electrode 51 on at least one side of the notch 53 is cut off.
3 was bent to avoid. The reason why the patterns of the two rows of individual electrodes 51 are point-symmetrical with respect to the center of the piezoelectric sheet 50 is that there are two rows of pressure chambers in the cavity plate, as described in an embodiment described later.

As a result, a space for providing the notch 53 as a positioning mark and an assembly mark can be secured. Thus, as shown in FIG. 10, the notch 53 formed on the side surface of the piezoelectric actuator 56 formed by laminating the piezoelectric sheets and the cavity plate 57 are formed.
The inkjet printer head is configured by combining the piezoelectric actuator 56 and the cavity plate 57 with the mark 58 formed on the surface of the piezoelectric actuator 56 being combined with the flexible flat cable 55 on the surface of the piezoelectric actuator 56.

[0008]

However, since the above-mentioned individual electrode has a bent portion, when such an electrode is printed by screen printing, the bent portion cannot be coated with a uniform electrode material. Irregularities occur on the surface. Due to the unevenness, the capacitance of the individual electrode beyond the bent portion is not constant, and there is a problem that the ink ejection becomes non-uniform or a defective ejection occurs.

Further, since the notch as an assembly mark with the cavity plate exists independently of the individual electrode, when the position of the individual electrode changes due to contraction in the sintering step of the piezoelectric actuator. However, the positional relationship between the individual electrodes and the notch as an assembly mark is unknown, and it is necessary to combine the pressure chambers of the cavity plate with the individual electrodes of the piezoelectric actuator. There was a problem that it could not be reflected on the assembly mark.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. The position of an internal electrode in a piezoelectric actuator is grasped from the outside, and a cavity plate and a piezoelectric actuator are connected in accordance with the position of the internal electrode. It is an object of the present invention to provide an ink jet printer head that can combine the above.

[0011]

In order to achieve this object, an ink jet printer head according to the present invention has a cavity plate having a plurality of nozzles and a pressure chamber formed for each of the plurality of nozzles. A plurality of internal electrodes provided corresponding to each of the pressure chambers and a piezoelectric actuator in which a plurality of piezoelectric sheets are stacked are stacked, and the internal electrodes of the piezoelectric sheet are arranged in the stacking direction of the piezoelectric sheets. The through-holes penetrated and the conductive material filled in the through-holes are electrically connected to each other, and at least one of the internal electrodes has
The piezoelectric sheet extends to the edge of the piezoelectric sheet.

According to the first aspect of the invention, the ink supplied from the ink supply source to the inkjet printer head is distributed to the plurality of pressure chambers provided in the cavity plate. The pressure inside the plurality of pressure chambers to which the ink is distributed fluctuates by the piezoelectric sheet that is fluctuated by the plurality of internal electrodes provided corresponding to each of the pressure chambers. Due to this pressure fluctuation, ink is ejected from a plurality of nozzles provided corresponding to the plurality of pressure chambers, and printing is performed.

Here, the piezoelectric actuator is formed by laminating a plurality of internal electrodes and a plurality of piezoelectric sheets. The internal electrodes of the piezoelectric sheet are filled with through holes penetrating in the laminating direction of the piezoelectric sheets and filling the through holes. Are electrically connected to each other by the conductive material. The position of the internal electrode is grasped by at least one internal electrode extending to the edge of the piezoelectric sheet among the plurality of internal electrodes, and the piezoelectric actuator and the cavity plate are associated with the pressure chambers of the cavity plate. To form an ink jet printer head.

According to a second aspect of the present invention, in the inkjet printer head according to the first aspect, each piezoelectric sheet of the piezoelectric actuator is provided with an internal electrode at a position corresponding to another piezoelectric sheet. The position of the extended internal electrode of the internal electrode extending to the edge of the piezoelectric sheet is the same in each piezoelectric sheet.

According to the ink jet printer head of the second aspect, it operates in the same manner as the ink jet printer head of the first aspect, and each internal electrode of each piezoelectric sheet of the piezoelectric actuator corresponds to another piezoelectric sheet. It is provided at the same position as each internal electrode. Then, the internal electrode of each piezoelectric sheet provided at the same position extends to the edge of the piezoelectric sheet.

According to a third aspect of the present invention, in the ink jet printer head according to the first or second aspect, the cavity plate includes a mark indicating a position of a pressure chamber corresponding to the extended internal electrode. .

According to a fourth aspect of the present invention, in the ink jet printer head according to any one of the first to third aspects, the pressure chambers are arranged in two rows, and the internal electrodes are connected to the pressure chamber. Corresponding to each row, two rows are arranged along the long side edge of the piezoelectric sheet, and at least one extended internal electrode is provided for each row of the internal electrodes.

According to the ink jet head printer of the fourth aspect, the ink jet printer operates in the same manner as the ink jet printer head of any one of the first to third aspects, and the pressure chambers are arranged in two rows. Are arranged in two rows along the long side edge of the piezoelectric sheet corresponding to each row of the pressure chambers. And at least one of the extended internal electrodes
One is provided for each column of internal electrodes.

According to a fifth aspect of the present invention, in the ink jet printer head according to the fourth aspect, the extended internal electrodes are provided substantially at the center of each row of the internal electrodes.

According to a sixth aspect of the present invention, in the inkjet printer head according to any one of the first to fifth aspects, the extended internal electrodes are linearly formed on each of the piezoelectric sheets.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view showing an embodiment of a color inkjet printer as an inkjet recording apparatus of the present invention. In FIG. 1, a color ink jet printer 100 includes, for example, an ink cartridge 61 filled with four color inks of cyan, magenta, yellow, and black, and an ink jet printer head 6 (hereinafter referred to as a head) for printing on paper 62. 6), a carriage 64 on which the ink cartridge 61 and the head unit 63 are mounted, and a drive unit 65 for reciprocating the carriage 64 in a linear direction.
A platen roller 66 that extends in the reciprocating direction of the carriage 64 and is disposed to face the head 6;
And

The drive unit 65 includes a carriage shaft 71 disposed at the lower end of the carriage 64 and extending parallel to the platen roller 66, a guide plate 72 disposed at the upper end of the carriage 64 and extending parallel to the carriage shaft 71, The pulley 73 includes two pulleys 73 and 74 disposed between the shaft 71 and the guide plate 72 at both ends of the carriage shaft 71, and an endless belt 75 stretched between the pulleys 73 and 74.

When one of the pulleys 73 is rotated forward and backward by the driving of the motor, the carriage 64 joined to the endless belt 75 is moved by the forward and reverse rotation of the pulley 73, and the carriage shaft 71 and the guide are rotated. It is reciprocated in a linear direction along the plate 72.

The paper 62 is formed by the ink jet printer 10.
The paper is fed from a paper feed cassette (not shown) provided on the side of the print head 0, is introduced between the head 6 and the platen roller 66, and performs predetermined printing with ink ejected from the head 6. Thereafter, the paper is discharged. In FIG. 1, illustration of a paper feed mechanism and a paper discharge mechanism of the paper 62 is omitted.

The purge device 67 is provided on the side of the platen roller 66, and is disposed so as to face the head 6 when the head unit 63 is at the reset position.
The purge device 67 includes a purge cap 81 that contacts an opening surface of the nozzle 6 so as to cover a plurality of nozzles, which will be described later, of the head 6, a pump 82, a cam 83, and an ink storage unit 84. Head unit 63
When the head 6 is at the reset position, the nozzle of the head 6 is covered with the purge cap 81, and the defective ink including air bubbles accumulated inside the head 6 is sucked by the pump 82 by driving the cam 83, so that the head 6 I try to recover. The sucked defective ink is stored in the ink storage unit 84.

The cap 85 covers a plurality of nozzles 15 (see FIG. 2) of the head 6 mounted on the carriage 64 which is returned to the reset position when printing is completed in order to prevent drying of the ink.

FIG. 2 shows the nozzle 15 of the head unit 63.
FIG. 2 shows a perspective view with the side up. As shown in FIG. 2, the head unit 63 mounted on the carriage 64 traveling along the sheet 62 is formed in a substantially box shape with an open top, and the four ink cartridges 61 from above.
The ink supply passages 4 a, 4 b, 4 c, and 4 d that can be connected to the ink discharge section of each ink cartridge 61 are provided on one side of the mounting section. To the lower surface of the. The ink supply passages 4a, 4b, 4c, and 4d have
A packing 47 made of rubber or the like, which can be in close contact with an ink supply hole 19a described later, is provided.

On the lower surface side of the bottom plate 5, four support portions 8 for arranging four heads 6 in parallel are formed in a stepped shape. A plurality of cavities 9a and 9b for fixing the head 6 with a UV adhesive are formed in each of the support portions 8 so as to penetrate vertically.

FIG. 3 is a perspective view of the head 6. As shown in FIG. 3, the head 6 includes a laminated cavity plate 10, a plate-type piezoelectric actuator 20 that is bonded and laminated to the cavity plate 10 via an adhesive or an adhesive sheet, and an upper surface thereof. For electrical connection with external devices, the flexible flat cable 40 is formed by overlapping and bonding with an adhesive,
Nozzle 1 opened on the lower surface side of cavity plate 10
Ink is ejected downward from 5. The piezoelectric actuator 20 will be described in detail with reference to FIG.

FIG. 4 is an exploded perspective view of the cavity plate 10. FIG. 5 shows the cavity plate 1
FIG. 5 is an exploded enlarged perspective view (cross section taken along the line VV in FIG. 3) of FIG. As shown in FIG. 4, the cavity plate 10 is formed by laminating five thin metal plates of a nozzle plate 11, two manifold plates 12X and 12Y, a spacer plate 13, and a base plate 14 with an adhesive, respectively. Structure. In the present embodiment, each of these plates 11 to 14 is a 42% nickel alloy steel plate (4
2 alloy), and has a thickness of about 50 μm to 150 μm. In addition, each of these plates 11 to 14 is not limited to being made of metal, and may be formed of, for example, resin.

As shown in FIG. 5, a plurality of narrow pressure chambers 16 extending in a direction perpendicular to the longitudinal direction of the base plate 14 are formed in the base plate 14 in two rows in a staggered arrangement. Further, on the spacer plate 13 side of the base plate 14, a throttle portion 16d connected to each pressure chamber 16 and an ink supply hole 16b connected to the throttle portion 16d are recessed. Each ink supply hole 16b
Are connected to the common ink chamber 12a in the manifold plate 12X through the respective ink supply holes 18 formed in the left and right sides of the spacer plate 13. Here, the cross-sectional area orthogonal to the direction in which the ink flows in each of the constricted portions 16 d is smaller than the cross-sectional area of each of the pressure chambers 16. This is the diaphragm 16d
Is to increase the flow path resistance by reducing the cross-sectional area of.

One end 16a of each pressure chamber 16 is connected to a staggered nozzle 15 of the nozzle plate 11 by a spacer plate 13 and two manifold plates 12
X and 12Y are communicated with each other via a small-diameter through hole 17 which is also formed in a staggered arrangement.

As shown in FIG. 4, the base plate 14 and the spacer plate 13 have two ink supply holes 19a for supplying ink from a common ink cartridge to two common ink chambers 12a in the manifold plate 12. 19b are respectively formed.

The ink supply holes 19a of the base plate 14
In order to reduce the size of the ink jet head, a plurality of pressure chambers 16 are formed near the ends of the rows. The ink supplied to the two ink supply holes 19a is:
Since the ink is supplied from a common ink cartridge, the two ink supply holes 19a are arranged close to each other.
The two ink supply holes 19a are connected to each other through two ink supply holes 19b formed in the spacer plate 13.
If two ink supply holes 19b on the spacer plate 13 are provided to supply ink to the corresponding two common ink chambers 12a, the number of ink supply holes 19a on the base plate 14 may be one. good.

Two manifold plates 12X, 12
In Y, as shown in FIG. 4, two common ink chambers 12 a and 12 b are provided with a row of the plurality of nozzles 15 in the nozzle plate 11 interposed therebetween. The common ink chambers 12a and 12b are located in a plane parallel to a plane formed by the plurality of pressure chambers 16 in the base plate 14,
Further, the nozzle plate 11 is more than the pressure chambers 16.
Are arranged on the opening surface side of the plurality of nozzles 15.

Of the two manifold plates, the manifold plate 12X on the spacer plate 13 side includes:
A common ink chamber 12a is formed through the manifold plate 12X, and the manifold plate 12Y on the nozzle plate 11 side is provided with the former manifold plate 1A.
It is recessed so as to open only to the 2X side. And
By laminating the two manifold plates 12X and 12Y and the spacer plate 13, the vertically overlapping common ink chambers 12a and 12b form one common ink chamber on each side of the row of the through holes 17. . Thereby, a sufficient amount of ink to be supplied to the plurality of pressure chambers 16 can be secured. The two rows of the common ink chambers are provided on both sides of the row of the through holes 17 so as to correspond to the pressure chambers 16 arranged in the two rows.

As shown in FIG. 4, the nozzle plate 11 is provided with a plurality of nozzles 15 for discharging ink having a very small diameter (about 25 μm in this embodiment).
Are formed in a zigzag arrangement at intervals of a minute pitch P along the longitudinal direction of.

With the above configuration of the cavity plate 10, the ink flowing into the common ink chambers 12a and 12b from the ink supply holes 19a and 19b formed at one end of the base plate 14 and the spacer plate 13 is supplied to the common ink chamber 12a. Is distributed to each pressure chamber 16 through each ink supply hole 18, each ink supply hole 16b, and the throttle portion 16d. Then, the ink flows in the direction of one end 16 a of each pressure chamber 16, passes through each through hole 17, and reaches the nozzle 15 corresponding to each pressure chamber 16.

FIG. 6 shows a plate type piezoelectric actuator 2.
FIG. 6 is an exploded perspective view of the plate-type piezoelectric actuator 20. As shown in FIG.
22, 23, 24, 25, 26, 27, 28, 29, 3
0 are formed in a laminated structure.

Of each of the piezoelectric sheets 21 to 30, on the upper surface of each of the piezoelectric sheets 26, 28 and 30, a narrow individual width is provided at a position corresponding to each of the pressure chambers 16 (see FIG. 5) provided in the cavity plate 10. Electrodes 31 are respectively formed. A discard pattern electrode 32b, which is a land pattern that does not contribute to the deformation of the piezoelectric sheet, is formed at a position corresponding to an end 32a of the common electrode 32 described later. The specific pattern of the individual electrode 31 will be described with reference to FIG.

On the upper surfaces of the piezoelectric sheets 25, 27 and 29,
A strip-shaped common electrode 32 serving as a common electrode is formed for the plurality of pressure chambers 16. In addition, the individual electrodes 3
The discarded pattern electrode 31 which is a land pattern not involved in the deformation of the piezoelectric sheet is provided at a position corresponding to the end 31a
b is formed. Discarded pattern electrodes 31b, 32b
Is formed to have the same thickness as the individual electrode 31 and the common electrode 32, and corrects the depression of the piezoelectric sheet where the individual electrode 31 and the common electrode 32 are not present when the piezoelectric sheets are stacked as described later. On the upper surfaces of the piezoelectric sheets 22, 23 and 24, the common electrode 32 and the discard pattern 31b are provided.
Are formed, but these sheets are not subjected to piezoelectric operation.

On the upper surface of the uppermost piezoelectric sheet 21, a surface electrode 33 for each of the individual electrodes 31 and a surface electrode 34 for the common electrode 32 are provided.
It is provided in two rows along the side edge extending in parallel with the arrangement direction of one.

Except for the lowermost piezoelectric sheet 30, all the other piezoelectric sheets 21 to 29 are further provided with the front surface electrode 33, the individual electrode 31 at the corresponding position (the same vertical position), and the discard pattern. A through hole 36 is formed so that the electrode 31b communicates with each other (see FIG. 7). Similarly, a through hole 37 is formed so that the surface electrode 34 and the common electrode 32a and the discarded pattern electrode 32b at the corresponding positions communicate with each other.

The through holes 36 and 37 are filled with a conductive material, so that the individual electrodes 31 of each layer are electrically connected to the surface electrode 33 at a position corresponding thereto. Are configured to be electrically connected to each other and the surface electrode 34 at a position corresponding to the common electrodes 32.

FIG. 7 is a diagram showing an arrangement pattern of the individual electrodes 31 and the discarded pattern electrodes 32b provided on the piezoelectric sheets 26, 28 and 30. As shown in FIG. 7, the pattern of the individual electrodes 31 in the row on one side of the long side end of each piezoelectric sheet 26 or the like is linear and perpendicular to the edge of the piezoelectric sheet 26 or the like. Formed to extend,
The pattern of the individual electrodes 31 in the row on the other side is in a staggered position shifted by half from the individual electrodes 31 in the row on the one side, and is orthogonal to the edge of the piezoelectric sheet 26 or the like. It is formed to extend in the direction.

The end 31a of each individual electrode 31 is not exposed from the edge of each piezoelectric sheet 26 or the like. The corresponding individual electrodes 31 of the respective piezoelectric sheets 26 and the like are electrically connected to each other by the through holes 36 and the conductive material filled in the through holes 36. This is because it is not necessary to expose the end 31a of each individual electrode 31 from the edge of each piezoelectric sheet 22 or the like, unlike the case where the individual electrodes 31 are electrically connected to each other by the side electrodes by exposing the individual electrodes 31. .

However, the end portions 31 of all the individual electrodes 31
If a is not exposed from each piezoelectric sheet 26 and the like, the position of the individual electrode 31 cannot be grasped from the outside when the piezoelectric sheets 26 and the like are stacked. Therefore, the individual electrodes 31 in each row formed on each piezoelectric sheet 26 and the like
Of the end portions 31X of the central individual electrode 31X
a is extended to the edge of each piezoelectric sheet 26 and the like to be exposed, and the end 31Xa is used as a mark indicating the position of the internal electrode.

The extension individual electrodes 31X are provided substantially at the center of each row of the individual electrodes 31. As described later, the piezoelectric actuator 20 is manufactured by stacking and sintering the piezoelectric sheets 22 and the like. However, in such a sintering process, shrinkage occurs, and the shrinkage slightly differs for each piezoelectric actuator, and the pitch of the individual electrodes 31 does not exactly match the pitch of the pressure chambers 16 of the cavity plate. If the assembly with the cavity plate 10 is performed with reference to the end 31Xa of the central extended individual electrode 31X, the positional error between the internal electrode 31 and the corresponding pressure chamber at both ends can be reduced.

The piezoelectric sheets 22, 23, 24, 2 provided at positions corresponding to the positions of the extended individual electrodes 31X.
Similarly, the ends of the discarded pattern electrodes 31b at 5, 27 and 29 and the ends of the surface electrodes 33 of the piezoelectric sheet 21 are also exposed from the respective piezoelectric sheets.

Next, a method of manufacturing the piezoelectric actuator will be described. First, a first material sheet (ceramic green sheet) having a size in which a plurality of piezoelectric sheets 26 (similarly, 28 and 30) are arranged in a matrix is formed, and each of the piezoelectric sheets 26 and 28 is formed. The through holes 36 and 37 are formed in advance along the periphery of the location where Similarly, the piezoelectric sheet 22 (2
3, 24, 25, 27, and 29) are formed in a matrix to form a second material sheet (ceramic green sheet) having a size, and along the periphery of each piezoelectric sheet portion. Through holes 37 and 36 are formed in advance. Further, in the same manner as described above, a third material sheet (ceramic green sheet) having a size in which a plurality of uppermost piezoelectric sheets 21 are arranged in a matrix is formed, and the uppermost piezoelectric sheet 21 of the surface is formed. Through hole 3 along the periphery of
Drill 6, 37.

Next, on the surface of the green sheet, the individual electrodes 31 and the discarded pattern electrodes 32b are provided for the portions to become the respective piezoelectric sheets 26, 28, 30. On the surface of the green sheet, the piezoelectric sheets 22, 23, 24, 25, Common electrode 32 and discarded pattern electrode 3
1b, the uppermost piezoelectric sheet 2
The surface electrodes 33 and 34 are formed on the surface of the portion to be 1 by screen printing of a conductive paste.

Here, since the through holes 36 and 37 penetrate through the upper and lower wide surfaces of the green sheets, the conductive paste penetrates into the through holes 36 and 37, respectively. Through each of the electrode portions, the upper and lower surfaces of the piezoelectric sheet can conduct electricity. Further, since each individual electrode 31 is formed in a straight line, the surface thereof can be printed more uniformly than in a case where there is a bend. Therefore, the capacitance in the individual electrode becomes constant, and stable ink ejection can be realized.

Further, since the extended internal electrodes 31X on the surfaces of the respective piezoelectric sheets 26, 28, 30 are all formed at the same position, the electrode arrangement of the respective piezoelectric sheets 26, 28, 30 must be printed in the same pattern. Can be. The same applies to other piezoelectric sheets.

Next, the green sheets are laminated. At this time, the individual electrode 31 of each sheet, the discard pattern electrode 31b
And the surface electrode 33 corresponds to the lamination direction, and the common electrode 3
The sheet 50 is laminated so that the end 32a, the discarded pattern electrode 32b and the surface electrode 33 correspond to the laminating direction and the surface electrodes 33 and 34 of the sheet 50 are exposed, degreased, sintered and integrated. As a result, the individual electrode 31 and the discarded pattern electrode 31b of each green sheet stacked vertically
The surface electrode 33 is electrically connected to the common electrode 32 and the discarded pattern electrode 32 through a through hole 36.
b and the surface electrode 33 are electrically connected through a through hole 37.

Thereafter, the laminate is cut for each piezoelectric actuator. At this time, each piezoelectric actuator 2
The end of the extended individual electrode 31 and the end of the central part of the discarded pattern electrode 33 are exposed on the side surface of the stacking direction 0.

The cavity plate 1 having the above configuration
0 and the piezoelectric actuator 20, as shown in FIG.
Each pressure chamber 16 in the cavity plate 10 and the individual electrode 31 in the piezoelectric actuator 20 are laminated and fixed so as to correspond to each other. FIG. 8 is a cross-sectional view of FIG.
FIG. 8 is a cross-sectional view of the piezoelectric actuator 20 and the cavity plate 10 along the line VIII.

The surface of the cavity plate 10 overlapping the piezoelectric actuator 20 is provided with a mark 39 indicating the position of the pressure chamber 16X corresponding to the extended individual electrode 31X. By combining the mark 39 with the end 31Xa of the extended individual electrode 31X exposed from the piezoelectric actuator 20, the end 31Xa of the extended individual electrode 31X can be used as an assembly mark between the piezoelectric actuator 20 and the cavity plate 10. In addition, the extension individual electrode 31
Since X is directly used as an assembly mark, the actual individual electrode 31 is used.
, The pressure chamber 16 can be accurately arranged.

A flexible flat cable 40 (see FIG. 3) 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 formed. It is electrically connected to each of the surface electrodes 33 and 34.

Then, through the flexible flat cable 40, a higher voltage is applied between all the individual electrodes 31 and the common electrode 32 than during the normal ink ejection operation, and the individual electrodes 31 and the common electrode 32 are connected to each other. The portions of the piezoelectric sheets 25 to 29 sandwiched therebetween are subjected to polarization processing, and those portions are formed as active layers. This polarization treatment can be performed before the piezoelectric actuator 20 is joined to the cavity plate 10 or the flexible flat cable 40.

Note that the piezoelectric sheets 21 to 24 are only sandwiched between the common electrodes 32 and between the surface electrodes 33 and 34 and are not polarized, so that they do not perform a piezoelectric operation. These sheets are used in order to prevent the piezoelectric actuator from warping or waving in the sintering step, thereby preventing the planarity from being impaired. Also, the active layers of the piezoelectric sheets 25 to 29 are deformed only in the direction of the pressure chamber 16. It functions as a constraining layer.

Then, of the individual electrodes 31 of the piezoelectric actuator 20 in the head 6, an arbitrary individual electrode 31
And a common electrode 32, a voltage is applied to the active layer of the piezoelectric sheet corresponding to the individual electrode 31 to which the voltage has been applied, so that distortion in the laminating direction due to piezoelectricity occurs. Then, the ink in the pressure chamber 16 is ejected from the nozzle 15 in the form of droplets by the pressure due to the distortion, and the paper 62
The predetermined printing is performed on the.

As described above, the head 6 according to the present embodiment
According to this, at least one of the individual electrodes 31 of each piezoelectric sheet 22 or the like extends to the edge of each piezoelectric sheet 22 or the like. Since the position of the individual electrode 31 can be confirmed from the outside, the end of the individual electrode 31 can be used as a mark indicating the position of the internal electrode.

The end 31 of the extended individual electrode 31X
By combining Xa with the mark 39 of the cavity plate 10, the cavity plate 10 and the piezoelectric actuator 20 can be combined according to the actual position of the individual electrode.

The present invention has been described based on the above embodiments. However, the present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the gist of the present invention. That can be easily inferred.

For example, in the above embodiment, only the individual electrode 31 at the center of the row formed by the individual electrodes 31 is the extended individual electrode 31X. However, the extended individual electrode 31X is not limited to the central individual electrode 31. Instead, every other individual electrode 31 may be provided in each row, or all the individual electrodes 31 may be extended. By exposing many internal electrodes 31, the position of each internal electrode 31 can be grasped more accurately than when exposing some internal electrodes 31.

Further, in the above embodiment, all the corresponding individual electrodes 31, pattern electrodes 31b, and surface electrodes 33 in the laminating direction of the piezoelectric actuator extend to the ends of the respective piezoelectric sheets and are exposed. When the exposed end is used as an assembly mark with the cavity plate 10, the cavity plate 10
If the individual electrodes 31 and the like are exposed from at least one layer of the piezoelectric sheet on the side, the other sheets may be omitted.

The end of the individual electrode 31 as an internal electrode extends to the edge of the piezoelectric sheet.
Are individually provided corresponding to the respective pressure chambers similarly to the individual electrode 31, and the end of the common electrode 32 also extends to the edge of the piezoelectric sheet, so that the internal electrode composed of the common electrode 32 and the individual electrode 31 is formed. The position can also be displayed on the side of the actuator.

[0068]

According to the first aspect of the present invention, the internal electrodes of the piezoelectric sheet are formed by the through-holes penetrating in the laminating direction of the piezoelectric sheets and the conductive material filled in the through-holes. Since at least one of the internal electrodes extends to the edge of the piezoelectric sheet, the end of the internal electrode extended to the edge of the piezoelectric sheet is It can be a mark indicating the position of the internal electrode. Therefore, unlike the related art, there is no need to provide a separate mark, and there is an effect that the position of the internal electrode can be grasped from the outside and the internal electrode can correspond to the pressure chamber.

According to the ink jet printer head according to the second aspect, in addition to the effect of the ink jet printer head according to the first aspect, each piezoelectric sheet of the piezoelectric actuator is provided at a position corresponding to another piezoelectric sheet. The internal electrodes are provided, and among the internal electrodes, the positions of the extended internal electrodes extending to the edge of the piezoelectric sheet are the same in each piezoelectric sheet. Is extended, the end of the extended internal electrode is formed linearly in the laminating direction on the side surface of the piezoelectric actuator. Accordingly, the ends of the plurality of extended internal electrodes formed in a straight line can be integrally captured, and the position of the internal electrode can be clearly grasped from the outside.

Further, the printed pattern of the internal electrode in each piezoelectric sheet becomes the same, which has the effect that the types of components can be reduced and the manufacturing process can be simplified. Furthermore, when the end of the internal electrode formed on the side surface of the piezoelectric actuator does not form a straight line,
Since there is a possibility that the internal electrodes are not electrically connected, there is an effect that such defective products can be quickly eliminated.

According to the ink jet printer head according to the third aspect, in addition to the effects of the ink jet printer head according to the first or second aspect, the cavity plate is located at the position of the pressure chamber corresponding to the extended internal electrode. Is provided, the end of the extended internal electrode can be used as an assembly mark between the piezoelectric actuator and the cavity plate by combining the mark with the end of the extended internal electrode exposed from the piezoelectric actuator. This has the effect.

Further, since the extended internal electrode is directly used as an assembly mark, for example, a notch or the like provided at the edge of the piezoelectric sheet is used as an assembly mark, corresponding to the actual position of the internal electrode. There is an effect that the cavity plate and the piezoelectric actuator can be assembled by associating the internal electrode of the piezoelectric actuator with the pressure of the cavity plate.

According to the ink jet printer head according to the fourth aspect, in addition to the effect of the ink jet printer head according to any one of the first to third aspects, the internal electrodes correspond to the respective rows of the pressure chambers. The sheet is arranged in two rows along the edge of the long side of the sheet, and at least one extended internal electrode is provided for each row of the internal electrodes. The end of at least one extended internal electrode is exposed. Therefore, when the piezoelectric actuator and the cavity plate are combined, there is an effect that assembly can be accurately performed by the assembly marks formed on both long sides.

According to the ink jet printer head of the fifth aspect, in addition to the effect of the ink jet printer head of the fourth aspect, the extended internal electrodes are provided substantially at the center of each row of the internal electrodes. Therefore, there is an effect that a position error when the internal electrode of the piezoelectric actuator and the corresponding pressure chamber of the cavity plate are overlapped can be reduced.

According to the ink jet printer head according to the sixth aspect, in addition to the effect of the ink jet printer head according to any one of the first to fifth aspects, the extended internal electrodes are formed linearly on each piezoelectric sheet. Therefore, for example, when the extended internal electrodes are printed by screen printing, the surface can be printed uniformly. That is, there is an effect that the electrostatic capacity in the extended internal electrode becomes constant and stable ink ejection can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a color inkjet printer which is an embodiment of an inkjet printer head of the present invention.

FIG. 2 is a perspective view of the head unit with the nozzle side facing upward.

FIG. 3 is a perspective view of each component of the inkjet printer head.

FIG. 4 is an exploded perspective view of a cavity plate.

FIG. 5 is an exploded enlarged perspective view of a cavity plate.

FIG. 6 is an exploded enlarged perspective view of a piezoelectric actuator.

FIG. 7 is a plan view showing a pattern of individual electrodes on a piezoelectric sheet.

FIG. 8 is an exploded enlarged perspective view of a piezoelectric actuator and a cavity plate.

FIG. 9 is a plan view showing patterns of individual electrodes in a conventional piezoelectric sheet.

FIG. 10 is a perspective view of each component of a conventional ink jet printer head.

[Explanation of symbols]

Reference Signs List 6 inkjet printer head 10 cavity plate 15 nozzle 20 piezoelectric actuator 21-30 piezoelectric sheet 31 individual electrode (internal electrode) 31a end of individual electrode 31X extended internal electrode 31Xa end of extended internal electrode 31b discarded pattern electrode 32 common electrode 32b Discarded pattern electrode 33, 34 Surface electrode 36, 37 Through hole 39 mark (cavity plate side assembly mark)

Claims (6)

[Claims] 1. A plurality of nozzles, a cavity plate having pressure chambers formed for each of the plurality of nozzles, and a plurality of internal electrodes and a plurality of piezoelectric sheets provided corresponding to each of the pressure chambers. In an ink-jet printer head configured by stacking a plurality of stacked piezoelectric actuators, the internal electrodes of the piezoelectric sheet are interconnected by a through hole penetrated in the stacking direction of the piezoelectric sheet and a conductive material filled in the through hole. Wherein at least one of the internal electrodes extends to the edge of the piezoelectric sheet. 2. Each of the piezoelectric sheets of the piezoelectric actuator is provided with an internal electrode at a position corresponding to another piezoelectric sheet, and each of the internal electrodes extends to an edge of the piezoelectric sheet. 2. The ink jet printer head according to claim 1, wherein the positions of the output internal electrodes are the same in each piezoelectric sheet. 3. The ink jet printer head according to claim 1, wherein the cavity plate has a mark indicating a position of the pressure chamber corresponding to the extended internal electrode. 4. The pressure chambers are arranged in two rows, and the internal electrodes are arranged in two rows along a long side edge of the piezoelectric sheet corresponding to each row of the pressure chambers. 4. The ink jet printer head according to claim 1, wherein at least one extended internal electrode is provided for each row of the internal electrodes. 5. The ink jet printer head according to claim 4, wherein the extended internal electrodes are provided substantially at the center of each row of the internal electrodes. 6. The ink jet printer head according to claim 1, wherein the extended internal electrodes are formed linearly on each of the piezoelectric sheets.