JP2003165215A - Ink jet printer head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet printer head in which failure of soldering can be prevented surely by enlarging the area of a land pattern and mounting densi ty of ink pressure chamber can be increased. <P>SOLUTION: On the upper surface part of a first piezoelectric layer 21, a substantially rhombic drive electrode 20A slightly smaller than and similar to the projection of an ink pressure chamber 19A is formed at a position corresponding to each ink pressure chamber 19A, and an arrow type land pattern 20B is formed continuously from the acute angle part of the drive electrode 20A. A through hole 20C is made substantially in the center of each land pattern 20B. On the upper surface part of a third piezoelectric layer 23, a large number of inner electrodes 23A of the substantially same shape as that of the drive electrode 20A and the land pattern 20B are formed. The land pattern 20B and the inner electrodes 23A are connected electrically with through-holes 30. <P>COPYRIGHT: (C)2003,JPO

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 land pattern for inputting a drive signal to a substantially rhombic drive electrode of a piezoelectric sheet laminated on a cavity plate, which has an acute angle. Related to an ink jet printer head capable of ensuring a large area of a land pattern, reliably preventing soldering failure, and improving the packaging density of ink pressure chambers by forming an arrow shape continuously from the portion Is.

[0002]

2. Description of the Related Art Conventionally, various ink jet printer heads using a laminated piezoelectric actuator have been proposed. For example, in an inkjet printer head described in US Pat. No. 5,402,159, a drive formed for each pressure chamber in a cavity plate having a plurality of nozzles and a pressure chamber for each nozzle. A plate-type piezoelectric actuator in which the piezoelectric sheets are laminated with the piezoelectric sheet sandwiched between the electrodes and a common electrode common to the adjacent pressure chambers is bonded. Further, in the ink jet print head described in Japanese Patent Publication No. 7-68003, a plurality of rows of rhombic pressure chambers are formed in the cavity plate, and the pressure adjacent to the drive electrode formed for each pressure chamber is adjacent. It is configured by stacking plate-type piezoelectric actuators in which the piezoelectric sheets are stacked with a common electrode common to the chambers sandwiching the piezoelectric sheets.

[0003]

SUMMARY OF THE INVENTION However, the piezoelectric sheet and the Japanese Patent Publication No.
In the piezoelectric sheet constituting the ink jet print head described in Japanese Patent No. 67803, in order to connect the drive electrode of each piezoelectric actuator and the power supply unit, a wire is pulled out to a position apart from the drive electrode to form a power supply unit. Was making a connection. In this case, the drive electrodes and the power source can be electrically connected, but a certain amount of space is required between the drive electrodes in order to ensure electrical insulation from the wiring provided. Therefore, there is a problem that the improvement of the packaging density of the pressure chamber arrangement is hindered. In addition, when a land pattern is formed continuously from the drive electrode, a certain amount of space is required for this land pattern, so that there is a problem that improvement of the packaging density of the pressure chamber arrangement is hindered.

Therefore, the present invention has been made in order to solve the above-mentioned problems, and ensures the reliable formation of the drive electrodes and the power supply section of the piezoelectric sheet formed corresponding to the positions where the ink pressure chambers are arranged. An object of the present invention is to provide an inkjet printer head that can be electrically connected and can improve the packaging density of ink pressure chambers.

[0005]

In order to achieve the above object, an ink jet printer head according to a first aspect of the present invention has a cavity plate in which a substantially rhombic ink pressure chamber is formed in a plan view and a shape of the ink pressure chamber. An ink jet printer head having a corresponding rhomboidal shape, a drive electrode that is arranged to face an ink pressure chamber, and a piezoelectric sheet that is laminated on the cavity plate. An arrow-shaped land pattern is formed continuously from the diamond-shaped acute-angled portion.

In the ink jet printer head according to the present invention having such a feature, the ink pressure chamber provided in the cavity plate is formed in a substantially rhombic shape. Further, the piezoelectric sheet laminated on the cavity plate is provided with drive electrodes of a substantially rhombic shape corresponding to the shape of the ink pressure chambers, facing the respective ink pressure chambers. In addition, an arrow-shaped land pattern is continuously formed on each of the drive electrodes from the diamond-shaped acute-angled portion. As a result, since the acute-angled portions of the ink pressure chambers of the plurality of rows are arranged so as to be inserted between the ink pressure chambers of the other rows, the drive electrodes formed facing one ink pressure chamber. An arrow-shaped land pattern is formed continuously from the acute-angled portion. Therefore, it becomes possible to bring each hypotenuse portion of the arrow-shaped land pattern closer to the hypotenuse portion of the outer edge of each acute angle portion of the drive electrode formed facing the other ink pressure chamber. It is possible to secure a large area for the soldering and reliably perform soldering to the land pattern. Further, since a large area of the land pattern is secured by effectively utilizing the space between the acute angle portions of each ink pressure chamber, it is possible to improve the packaging density of the ink pressure chambers.

An ink jet printer head according to a second aspect of the present invention is the ink jet printer head according to the first aspect, wherein the piezoelectric sheet is composed of a laminated body in which a plurality of piezoelectric layers are laminated. .

According to a second aspect of the present invention, in the ink jet printer head according to the first aspect, the piezoelectric sheet is composed of a laminated body in which a plurality of piezoelectric layers are laminated. By changing the electric field applied to each piezoelectric layer, it is possible to generate a large deflection in the thickness direction as compared with the case where the piezoelectric layer is a single layer. Therefore, in the piezoelectric sheet, a desired ink amount can be ejected even if the area occupied by the portion of the piezoelectric sheet that causes such bending in the thickness direction is small, so that the packaging density of the ink pressure chambers is further improved. Can be made.

An ink jet printer head according to a third aspect is the ink jet printer head according to the first or second aspect, wherein a plurality of ink pressure chambers are formed in the cavity plate and the piezoelectric sheet is provided. Is formed with a plurality of drive electrodes, and the piezoelectric sheet is laminated on the cavity plate such that each drive electrode faces an individual ink pressure chamber.

According to a third aspect of the present invention, there is provided the ink jet printer head according to the first or second aspect, wherein the piezoelectric sheet has a plurality of ink pressures formed on the cavity plate. A drive electrode is formed so as to face the chamber. For this reason, since each drive electrode is also laminated with respect to the corresponding ink pressure chamber in the lamination direction of the piezoelectric sheet on the cavity plate, the ink jet printer head can be configured while maintaining a high packaging density of the ink pressure chamber. it can.

An ink jet printer head according to a fourth aspect is the ink jet printer head according to the second or third aspect, wherein the piezoelectric layer inside the laminate corresponds to the shape of the ink pressure chamber. An internal electrode having a substantially rhombic shape and arranged to face each ink pressure chamber is formed, and a through hole electrically connecting the drive electrode and the internal electrode is formed. And

According to a fourth aspect of the present invention, there is provided the ink jet printer head according to the second or third aspect, wherein the piezoelectric layer inside the laminate has the ink pressure chamber of the ink pressure chamber. An internal electrode is formed which has a substantially rhombic shape corresponding to the shape and is arranged to face each ink pressure chamber. Further, the internal electrode and the drive electrode are electrically connected by a through hole. As a result, since the internal electrode and the drive electrode are electrically connected to each other through the through hole in the thickness direction, it is not necessary to provide a space for drawing the wiring from the internal electrode between the ink pressure chambers, and The packaging density can be improved. Further, since the internal electrodes and the drive electrodes are electrically connected to each other through the through-holes in the thickness direction, a desired ink amount can be obtained even if the area occupied by the layered body that causes the bending in the thickness direction is small. Since the ink can be ejected, the packaging density of the ink pressure chambers can be reliably improved.

An ink jet printer head according to a fifth aspect is the ink jet printer head according to the fourth aspect, wherein the through hole is formed in the land pattern having the arrow shape.

According to a fifth aspect of the present invention, in the ink jet printer head according to the fourth aspect, internal electrodes are formed on the laminated body to form the arrow-shaped land pattern. Has a through hole electrically connected to the internal electrode. As a result, since the internal electrode and the land pattern are electrically connected to each other through the through hole in the thickness direction, it is not necessary to provide a space for drawing the wiring from the internal electrode between the ink pressure chambers. The packaging density can be improved. Further, since the internal electrode and the land pattern are electrically connected by the through hole formed in the arrow-shaped land pattern, the area of the drive electrode corresponding to the portion that causes bending in the thickness direction of the laminated body is Since the through hole is not reduced by forming it, it is not necessary to increase the apparent occupied area of the drive electrode by compensating for the reduced electrode area in order to eject a desired ink amount. This allows
The high packing density of the ink pressure chambers can be maintained more reliably.

Furthermore, an ink jet printer head according to a sixth aspect is the ink jet printer head according to the fourth or fifth aspect, wherein the through holes electrically connected to the internal electrodes are filled with a conductive material. It is characterized by

According to a sixth aspect of the ink jet printer head having such a feature, in the ink jet printer head according to the fourth or fifth aspect, an arrow-shaped land pattern electrically connected to the internal electrodes is formed. Since the formed through holes are filled with the conductive material, the internal electrodes and the land pattern are surely electrically connected to each other, and the internal electrodes of the flexible printed wiring board (FPC: Flexible Printed Circuit) are connected to the land portions. The electrical connection can be reliably performed.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an ink jet printer head according to the present invention will be described below with reference to the drawings. First, a schematic configuration of the inkjet printer head according to the present embodiment will be described with reference to FIGS. 1 to 4. FIG. 1 is an exploded perspective view of an inkjet printer head according to this embodiment. FIG. 2 is an exploded perspective view of essential parts of the piezoelectric sheet and the cavity plate of the inkjet printer head according to the present embodiment. 3A and 3B are views showing a schematic configuration of an ink pressure chamber and a drive electrode of the inkjet printer head according to the present embodiment, FIG. 3A is a plan view, and FIG. FIG. 4 is an enlarged perspective view of an essential part schematically showing the arrangement configuration of the drive electrodes formed on the piezoelectric sheet of the inkjet printer head according to the present embodiment.

As shown in FIGS. 1 to 4, an ink jet printer head 1 has a substantially trapezoidal shape in plan view or a substantially parallelogram shape in plan view on a cavity plate 2 having a laminated structure of thin metal plates formed in a substantially rectangular shape. Plate type 5
Each of the piezoelectric sheets 20, 20, 20, 20, 20 has a structure in which they are laminated in a state of being adjacent to each other. Also,
On the surface of the cavity plate 2, a plurality of rows of ink pressure chambers 19A formed in a substantially rhombic shape are arranged corresponding to a required printing density. Further, the ink pressure chambers 19A in the plurality of rows are arranged at a high density so that the acute-angled portions of the ink pressure chambers 19A are inserted between the ink pressure chambers 19A in the other rows.

The cavity plate 2 has a nine-layer structure in which nine substantially rectangular metal plate members are laminated.
Specifically, as shown in FIG. 3 (B), the cavity plate 2 includes a nozzle plate 11, a cover plate 12, a first manifold plate 13, a second manifold plate 14, a third manifold plate 15, from the lower layer.
It has a structure in which nine thin metal plates of a supply plate 16, an aperture plate 17, a spacer plate 18, and a base plate 19 are laminated. Further, as shown in FIG. 1, filter holes 19B and 19B to which ink is supplied are formed at both end portions in the longitudinal direction of the cavity plate 2, and these filter holes 19B and 19B are filled with ink inside the ink. The filters 21, 21 each having a plurality of fine through holes for preventing dust from entering are stacked.

As shown in FIG. 3, the nozzle plate 11 is provided with a large number of minute nozzles 11A for ejecting ink. In addition, the cover plate 12 includes
A large number of through holes 12A, which are passages of ink of a small diameter, which communicate with the nozzles 11A, are formed at positions facing the nozzles 11A, and the manifold plates 13, 14 are provided.
It constitutes one wall surface of an ink manifold passage described later formed by 15.

In the first manifold plate 13, the through hole 12A is provided at a position facing the through hole 12A.
A large number of through holes 13A, which are passages of a minute diameter ink communicating with the ink pressure chambers 19A of the ink pressure chambers 19A, are formed so that the groove-like holes 13B constituting the ink manifold passages extend in the longitudinal direction. Multiple rows are formed along each row.

The second manifold plate 14 has a through hole 13A at a position facing the through hole 13A.
A large number of through-holes 14A, which are passages of ink having a small diameter, are formed in the ink pressure chambers 19A so that the groove-shaped holes 14B forming the ink manifold passages extend in the longitudinal direction. Multiple rows are formed along each row.

The third manifold plate 15 has a through hole 14A at a position facing the through hole 14A.
A large number of through-holes 15A, which are passages of ink having a minute diameter, are formed in the ink pressure chambers 19A so that the groove-like holes 15B forming the ink manifold passages extend in the longitudinal direction. Multiple rows are formed along each row.

Further, the supply plate 16 is provided with a large number of through holes 16A which are passages of ink having a small diameter and which communicate with the through holes 15A, at positions facing the through holes 15A. In addition, the through hole 1 of the supply plate 16
6A in a diagonal direction opposite to the acute angle portion of the ink pressure chamber 19A and in the vicinity of the side edge portion of the hole 15B (in the vicinity of the right edge portion in FIG. 3B). Has a large number of through holes 16B which communicate with the ink manifold passage and form an ink supply passage.

Here, as shown in FIG. 3B, the upper surface of the cover plate 12, the groove-shaped holes 13B and 14B,
15B and the bottom surface of the supply plate 16, and a plurality of rows of ink manifold passages are formed in the longitudinal direction that serve as a common ink chamber that supplies ink to each ink pressure chamber 19A.

Further, the aperture plate 17 is provided with a large number of through holes 17A which are passages of ink having a minute diameter and which communicate with the through holes 16A. Further, the aperture plate 17 is provided with a through hole 17B at a position below the acute angle portion on the ink supply side of each ink pressure chamber 19A, and the through hole 16B is formed from the lower end portion of the through hole 17B.
Aperture portion 17 which is a groove-shaped recess up to the position facing
C is formed on the bottom surface. This aperture part 17C
Is formed in a groove having a depth of about half the thickness of the aperture plate 17.

Further, the spacer plate 18 is provided with a large number of through holes 18A communicating with the respective through holes 17A. Further, the spacer plate 18 is provided with a large number of through holes 18B communicating with the through holes 17B.

Further, the base plate 19 is provided with a large number of substantially rhombic ink pressure chambers 19A. Also,
Through holes 18 formed in the spacer plate 18
A and 18B are arranged so as to face each acute angle portion of the ink pressure chamber 19A. The upper surface of each ink pressure chamber 19A has a piezoelectric sheet 2 laminated on the upper side.
It is blocked by 0, 20, 20, 20, 20.

Further, on the upper surface portion of the piezoelectric sheet 20, a drive electrode 20A having a substantially rhombic shape which is slightly similar to the projected shape of the rhombic ink pressure chamber 19A is provided at a position corresponding to each ink pressure chamber 19A. Are formed. Further, as shown in FIG. 3A, an arrow-shaped land pattern 20B is formed continuously from the acute angle portion of the drive electrode 20A corresponding to the acute angle portion of the ink pressure chamber 19A on the ink supply side.

Next, a schematic structure of the piezoelectric sheet 20 and an electrical connection structure between the piezoelectric sheet 20 and a flexible printed wiring board (FPC) extending from a power supply circuit section (not shown) will be described with reference to FIGS. 5 and 6. It will be described based on. FIG. 5 is an enlarged vertical cross-sectional view of a main part of the piezoelectric sheet 20 of the inkjet printer head 1 according to this embodiment. FIG. 6 is an exploded perspective view schematically showing the electrical connection structure inside the piezoelectric sheet 20 of the inkjet printer head 1 according to this embodiment. As shown in FIGS. 5 and 6, the piezoelectric sheet 20
Is formed in a structure in which five first piezoelectric layers 21, second piezoelectric layers 22, third piezoelectric layers 23, fourth piezoelectric layers 24, and fifth piezoelectric layers 25 are laminated. Further, on the upper surface portion of the first piezoelectric layer 21, the substantially rhombic drive electrode 20A having a substantially similar shape slightly smaller than the projected shape of the ink pressure chamber 19A is provided at the position corresponding to each ink pressure chamber 19A as described above. An arrow-shaped land pattern 20B is formed continuously from the acute angle portion of the drive electrode 20A. Further, a through hole 20C is formed in the substantially central portion of each land pattern 20B.

The second piezoelectric layer 22 has the through hole 20.
A large number of through holes 22A are formed at positions facing C. Then, on the upper surface of the second piezoelectric layer 22, a common electrode 22B is formed over almost the entire surface, except for the position near the upper edge of each through hole 22A. Further, the end portion of the common electrode 22B is formed so as to be exposed at the side surface end portion of the second piezoelectric layer 22.

A large number of internal electrodes 23A having substantially the same shape as the drive electrodes 20A and the land patterns 20B are formed on the upper surface of the third piezoelectric layer 23 at positions corresponding to the drive electrodes 20A and the land patterns 20B. Has been done.

A common electrode 24A is formed on the upper surface of the fourth piezoelectric layer 24 over almost the entire surface. Further, the end portion of the common electrode 24A is formed so as to be exposed at the side surface end portion of the fourth piezoelectric layer 24.

No electrode is formed on the upper surface of the fifth piezoelectric layer 25. Here, each through hole 20C of the first piezoelectric layer 21 and each through hole 22A of the second piezoelectric layer 22 are communicated with each other to form each through hole 30, and a conductive material (for example, a conductive material) is formed in each through hole 30. , Tungsten, molybdenum, etc.). As a result, each land pattern 20B and each internal electrode 23A is connected to the through hole 30.
Are electrically connected via.

As shown in FIG. 5, the piezoelectric sheet 20 is used.
A flexible printed wiring board (FPC) 32 extending from a power circuit section (not shown) is disposed on the upper surface of the.
The FPC 32 includes a conductor portion 33 made of copper foil wired up to a position facing each land pattern 20B,
The base film 34 is adhered to the upper surfaces of the conductors 33, and the cover film 35 is adhered to the lower surfaces of the conductors 33. In addition, a large number of through holes 35A are formed in the cover film 35 at positions facing the respective land patterns 20B, that is, at the edge portions of the conductor portions 33. Then, each through hole 35 of the conductor portion 33
Preliminary solder 36 for connecting to each land pattern 20B is formed in a portion corresponding to A. Therefore, the conductor portions 33 and the land patterns 20B are bonded to each other and the through holes 30 are formed by superimposing and soldering the preliminary solders 36 on the respective land patterns 20B.
Each conductor part 33 and each internal electrode 23A are electrically connected via.

Of the first to fifth piezoelectric layers 21, 22, 23, 24, 25 configured as described above, the drive electrode 20A of the first piezoelectric layer 21 and the third piezoelectric layer 2 via the FPC 32.
Internal electrode 23A of No. 3 and the common electrode 2 of the second piezoelectric layer 22
2B and the common electrode 24A of the fourth piezoelectric layer 24, by applying a drive voltage, the first to fifth piezoelectric layers 2
1, 22, 23, 24, 25 can be deformed to apply pressure to the ink in the corresponding ink pressure chamber 19A of the cavity plate 2.

Therefore, the first to third piezoelectric layers 21, 22,
The portion of 23 corresponding to the drive electrode 20A and the internal electrode 23A constitutes an active portion that bends when a voltage is applied. In addition, the first to fifth piezoelectric layers 21, 22, 23, 24, 25
In the case of firing, since the shrinkage rate when firing is different between the piezoelectric ceramics and the metal material forming the electrodes, the entire sheet may be warped or corrugated. The fourth and fifth piezoelectric layers 24 and 25 prevent the flatness of the first to fifth piezoelectric layers 21, 22, 23, 24, 25 from being warped or corrugated after firing. Therefore, the active portions of the first to third piezoelectric layers 21, 22, and 23 function as a constraining layer for deforming only in the direction of the ink pressure chamber 19A.

Next, the operation of the ink jet printer head 1 configured as described above will be described with reference to FIG. As shown in FIG. 3, the upper surface portion of the cover plate 12,
The ink supplied from the ink manifold passage constituted by the groove-shaped holes 13B, 14B, 15B and the bottom surface of the supply plate 16 passes through the through hole 16B, the aperture portion 17C, the through hole 17B and the through hole 18B. , Into the ink pressure chamber 19A. Then, the land pattern 20B and each of the common electrodes 22B and 24 via the FPC 32.
When a drive voltage is applied between the piezoelectric sheet 20 and A, the piezoelectric sheet 20 is deformed to the ink pressure chamber 19A side, and the ink pressure chamber 19A
The ink in the inside is pushed out, and each through hole 18A, 17A, 1
It is discharged from the nozzle 11A through 6A, 15A, 14A, 13A and 12A.

As described in detail above, in the ink jet printer head 1 of this embodiment, the cavity plate 2 has a structure in which the plates 11 to 19 formed of nine thin metal plates are laminated. In addition, the base plate 19 has a substantially rhombus-shaped ink pressure chamber 19
Many A are formed. The upper surface of each ink pressure chamber 19A has a piezoelectric sheet 2 laminated on the upper side.
It is blocked by 0, 20, 20, 20, 20. The piezoelectric sheet 20 has a structure in which five first to fifth piezoelectric layers 21, 22, 23, 24 and 25 are laminated. In addition, at positions corresponding to the ink pressure chambers 19A of the first piezoelectric layer 21, the drive electrodes 2 having a similar rhombic shape are formed.
0A is formed. The drive electrode 20A may have an acute angle portion, and a parallelogram is also included in this substantially rhombic shape. Further, an arrow-shaped land pattern 20B is formed continuously from the acute angle portion of the drive electrode 20A. Further, each drive electrode 20A of the third piezoelectric layer 23
A large number of internal electrodes 23A having substantially the same shape are formed at the positions corresponding to the land patterns 20B. And
The land pattern 20B and the internal electrode 23A are electrically connected to each other through a through hole 30 filled with a conductive material. Also, the second and fourth piezoelectric layers 22, 2
Common electrodes 22B and 24A are formed on the upper surface of No. 4. Then, when a drive voltage is applied to the land pattern 20B via the FPC 32, the active portion formed at a portion corresponding to the drive electrode 20A and the internal electrode 23A of the piezoelectric sheet 20 is deformed and the inside of the ink pressure chamber 19A is deformed. Ink is ejected.

Therefore, when the acute-angled portions of the ink pressure chambers 19A in the plurality of rows are arranged so as to be inserted between the ink pressure chambers 19A in the other rows, the drive formed to face one ink pressure chamber 19A. Since the arrow-shaped land pattern 20B is continuously formed from the acute-angled portion of the electrode 20A, each oblique side of the arrow-shaped land pattern 20B is formed so as to face another ink pressure chamber 19A. Since it is possible to bring it closer to the hypotenuse of the outer edge of each acute angle portion and to secure a large area of the land pattern 20B, it is possible to reliably perform soldering to the land pattern 20B. In addition, the space between the acute-angled portions of each ink pressure chamber 19A is effectively utilized to make the land pattern 2
Since it is possible to easily secure the area required for soldering 0B, it is possible to improve the mounting density of the ink pressure chambers 19A. Furthermore, since the land pattern 20B is formed in the vicinity of the drive electrode 20A, it is possible to prevent an increase in capacitance. In the inkjet printer head 1 described in the present embodiment, the driving electrode 2
0A or the land pattern 20B, if wiring is to be joined to the FPC 32 that is electrically connected to the power source section outside the area where the electrodes are arranged, the wiring to the drive electrodes 20A or the land pattern 20B Since the lengths are different and the lengths are longer, the capacitances are unnecessarily increased in different sizes, and the response characteristics to ink ejection are deteriorated and variations occur. It is not a good idea to run the wiring for each electrode in this way,
Not only is the drive characteristic of the inkjet printer head 1 adversely affected, but a space for disposition is also required, which is disadvantageous in terms of realizing high-density mounting.

Since the piezoelectric sheet 20 has a structure in which five first to fifth piezoelectric layers 21, 22, 23, 24 and 25 are laminated, the first to third piezoelectric layers 21, 22,
23, that is, a large deflection can be generated in the thickness direction by changing the electric field of the piezoelectric layer of about half the layer with respect to the center line in the thickness direction. Therefore, in the piezoelectric sheet 20, a desired ink amount can be ejected even if the area occupied by the active portion that causes such bending in the thickness direction is small, and thus the mounting density of the ink pressure chambers 19A is further improved. be able to. In addition, the first to fifth thin films
By stacking the piezoelectric layers 21, 22, 23, 24, 25, it is possible to increase the deformation efficiency of the piezoelectric element with respect to the unit capacitance, and it is possible to reduce the size and cost of the drive power supply circuit.

By stacking the piezoelectric sheets 20 having a predetermined shape over the ink pressure chambers 19A of the cavity plate 2, it is possible to individually apply pressure to the ink in each ink pressure chamber 19A of the cavity plate 2. Therefore, the number of assembling steps can be reduced and the manufacturing cost can be reduced. In addition, the upper surface of the substantially rectangular cavity plate 2 is provided with five piezoelectric sheets 20, 20, 20, 20, 2.
Since it is closed by 0 and 20, the size of each piezoelectric sheet 20 can be reduced, and the dimensional accuracy after firing can be improved. Of course, since the drive electrodes 20A are also stacked with respect to the corresponding ink pressure chambers 19A in the stacking direction of the piezoelectric sheet 20 on the cavity plate 2, the inkjet printer head 1 with the high mounting density of the ink pressure chambers 19A maintained. Can be configured.

In addition, the internal electrode 23A and the land pattern 2
0B is electrically connected through the through hole 30 in the thickness direction, so that it is not necessary to provide a space for drawing the wiring from the internal electrode 23A between the ink pressure chambers 19A, and the mounting density of the ink pressure chambers 19A can be reduced. It is possible to improve. In addition, the internal electrode 23A and the land pattern 20B
Since and are electrically connected by the through hole 30, it is possible to prevent an unnecessary increase in capacitance. In addition, the through hole 30 is not necessarily the land pattern 20.
The drive electrode 20A and the internal electrode 23A, which are provided corresponding to the position of the ink pressure chamber 19A, may be provided so as to be electrically connected to each other, without being provided at the position B. Further, since only the land pattern 20B can be electrically connected to the flexible printed wiring board (FPC) 32, the influence on the deformation of the piezoelectric sheet 20 can be prevented. In particular, the through holes 3 are formed in the land pattern 20B.
When 0 is provided, there is no reduction in the area of the drive electrode 20A forming the active portion due to the through hole 30, so it is not necessary to compensate for this reduction and increase the apparent electrode area. As a result, the high mounting density of the ink pressure chamber 19A is not impaired.

Further, since the through hole 30 electrically connected to the internal electrode 23A is filled with the conductive material, the internal electrode 23A and the land pattern 20B are surely electrically connected and the flexible printed wiring is provided. Internal electrode 23 for pre-solder 36 of plate (FPC) 32
The electrical connection of A can be reliably performed.

The present invention is not limited to the above embodiment, and it goes without saying that various improvements and modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, the drive electrode 20A and the land pattern 20 are used.
B is formed substantially within the projected shape of the ink pressure chamber 19A (see FIG. 5), but as shown in FIG. 7, the land pattern 41 in the shape of an arrow on the piezoelectric sheet 20 is projected onto the projected shape of the ink pressure chamber 19A. It may be formed on the outer side of the ink pressure chamber 19A by enlarging it within the projected shape of the acute angle portion of each ink pressure chamber 19A. As a result, the electrical connection between the preliminary solder portion of the FPC 32 and each land pattern 41 can be performed more reliably. Here, FIG. 7 is an enlarged perspective view of an essential part schematically showing the arrangement configuration of the drive electrodes 20A formed on the piezoelectric sheet 20 of the inkjet printer head according to another embodiment. In FIG. 7, the same reference numerals as those of the inkjet printer head 1 according to the present embodiment indicate the same or corresponding portions as the inkjet printer head 1.

[0046]

As described above, in the ink jet printer head according to the first aspect, the ink pressure chamber provided in the cavity plate is formed in a substantially rhombic shape. Further, the piezoelectric sheet laminated on the cavity plate is provided with drive electrodes of a substantially rhombic shape corresponding to the shape of the ink pressure chambers, facing the respective ink pressure chambers. In addition, an arrow-shaped land pattern is continuously formed on each of the drive electrodes from the diamond-shaped acute-angled portion. As a result, since the acute-angled portions of the ink pressure chambers of the plurality of rows are arranged so as to be inserted between the ink pressure chambers of the other rows, the drive electrodes formed facing one ink pressure chamber. An arrow-shaped land pattern is formed continuously from the acute-angled portion. Therefore, it becomes possible to bring each hypotenuse portion of the arrow-shaped land pattern closer to the hypotenuse portion of the outer edge of each acute angle portion of the drive electrode formed facing the other ink pressure chamber. It is possible to provide an ink jet printer head which can secure a large area and reliably solder to the land pattern. Further, since a wide area of the land pattern is secured by effectively utilizing the space between the acute angle portions of each ink pressure chamber, it is possible to provide an inkjet printer head capable of improving the mounting density of the ink pressure chambers. You can

Further, in the ink jet printer head according to the second aspect, in the ink jet printer head according to the first aspect, since the piezoelectric sheet is composed of a laminated body in which a plurality of piezoelectric layers are laminated, each piezoelectric sheet. By changing the electric field applied to the layer, it is possible to generate a large deflection in the thickness direction as compared with the case where the piezoelectric layer is a single layer. Therefore, in the piezoelectric sheet, a desired ink amount can be ejected even if the area occupied by the portion of the piezoelectric sheet that causes such bending in the thickness direction is small, so that the packaging density of the ink pressure chambers is further improved. It is possible to provide an inkjet printer head capable of performing the above.

According to a third aspect of the present invention, there is provided the ink jet printer head according to the first or second aspect, wherein the piezoelectric sheet faces the plurality of ink pressure chambers formed in the cavity plate. The drive electrode is formed so that The piezoelectric sheet is provided so as to be laminated on the cavity plate so that each drive electrode faces each ink pressure chamber. As a result, by stacking the piezoelectric sheets having a predetermined shape across the ink pressure chambers of the cavity plate, the ink can be individually applied to the ink in the ink pressure chambers of the cavity plate.
It is possible to provide an inkjet printer head while maintaining a high packaging density of ink pressure chambers.

According to a fourth aspect of the present invention, in the ink jet printer head according to the second or third aspect, the piezoelectric layer inside the laminate corresponds to the shape of the ink pressure chamber. An internal electrode having a substantially rhombic shape is formed so as to be opposed to each ink pressure chamber. Further, the internal electrode and the drive electrode are electrically connected by a through hole. As a result, since the internal electrode and the drive electrode are electrically connected to each other through the through hole in the thickness direction, it is not necessary to provide a space for drawing the wiring from the internal electrode between the ink pressure chambers, and It is possible to provide an inkjet printer head capable of improving the packaging density. Further, since the internal electrodes and the drive electrodes are electrically connected by the through holes along the thickness direction, a desired ink amount can be obtained even if the area occupied by the portion that causes the bending in the thickness direction of the laminate is small. Since the ink can be ejected, it is possible to provide an inkjet printer head that can surely maintain a high packaging density of the ink pressure chambers and improve the density.

According to a fifth aspect of the present invention, in the ink jet printer head according to the fourth aspect, internal electrodes are formed on the laminate, and the land pattern in the shape of the arrow has
Through holes that are electrically connected to the internal electrodes are formed. As a result, since the internal electrode and the land pattern are electrically connected to each other through the through hole in the thickness direction, it is not necessary to provide a space for drawing the wiring from the internal electrode between the ink pressure chambers. It is possible to provide an inkjet printer head capable of improving the packaging density. Further, since the internal electrode and the land pattern are electrically connected by the through hole formed in the arrow-shaped land pattern, the area of the drive electrode corresponding to the portion that causes bending in the thickness direction of the laminated body is Since the through hole is not reduced by forming it, it is not necessary to increase the apparent occupied area of the drive electrode by compensating for the reduced electrode area in order to eject a desired ink amount. As a result, it is possible to provide an inkjet printer head in which the high packaging density of the ink pressure chambers is more reliably maintained.

Further, in the ink jet printer head according to a sixth aspect, in the ink jet printer head according to the fourth or fifth aspect, a through formed in an arrow-shaped land pattern electrically connected to the internal electrode is formed. Since the holes are filled with the conductive material, the internal electrodes and the land patterns are surely electrically connected and the flexible printed wiring board (FPC:
It is possible to provide an inkjet printer head capable of reliably electrically connecting the internal electrode to the land portion of the flexible printed circuit).

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an inkjet printer head according to an embodiment.

FIG. 2 is an exploded perspective view of essential parts of a piezoelectric sheet and a cavity plate of the inkjet printer head according to the present embodiment.

FIG. 3 is a diagram showing a schematic configuration of an ink pressure chamber and a drive electrode of the inkjet printer head according to the present embodiment,
(A) is a plan view and (B) is a longitudinal sectional view.

FIG. 4 is an enlarged perspective view of an essential part schematically showing the arrangement configuration of drive electrodes formed on the piezoelectric sheet of the inkjet printer head according to the present embodiment.

FIG. 5 is an enlarged vertical cross-sectional view of a main part of the piezoelectric sheet of the inkjet printer head according to the present embodiment.

FIG. 6 is an exploded perspective view schematically showing the electrical connection structure inside the piezoelectric sheet of the inkjet printer head according to the present embodiment.

FIG. 7 is an enlarged perspective view of essential parts schematically showing the arrangement configuration of drive electrodes formed on a piezoelectric sheet of an inkjet printer head according to another embodiment.

[Explanation of symbols]

1 Inkjet printer head 2 Cavity plate 11 nozzle plate 12 cover plate 13 1st manifold plate 14 Second manifold plate 15 Third manifold plate 16 supply plates 17 Aperture plate 18 Spacer plate 19 base plate 19A ink pressure chamber 20 Piezoelectric sheet 20A drive electrode 20B land pattern 20C, 22A through hole 21 First Piezoelectric Layer 22 Second piezoelectric layer 22B, 24A common electrode 23 Third Piezoelectric Layer 23A internal electrode 24 Fourth Piezoelectric Layer 25 fifth piezoelectric layer 30 through holes 32 FPC 33 Conductor 36 Spare solder

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Jun Hirota             Brother, 15-1, Naeshiro-cho, Mizuho-ku, Nagoya             Industry Co., Ltd. F-term (reference) 2C057 AF36 AF93 AG48 AG90 AG93                       AP02 AP14 AQ06 BA03 BA14

Claims (6)

[Claims] 1. A cavity plate in which an ink pressure chamber having a substantially rhombic shape in plan view is formed, and a drive which has a substantially rhombic shape corresponding to the shape of the ink pressure chamber and is arranged so as to face the ink pressure chamber. An inkjet printer head having an electrode and a piezoelectric sheet laminated on the cavity plate, wherein an arrow-shaped land pattern is continuously formed from the diamond-shaped acute-angled portion of the drive electrode. An inkjet printer head characterized in that 2. The ink jet printer head according to claim 1, wherein the piezoelectric sheet is composed of a laminated body in which a plurality of piezoelectric layers are laminated. 3. A plurality of ink pressure chambers are formed in the cavity plate, and a plurality of drive electrodes are formed in the piezoelectric sheet. In the piezoelectric sheet, each drive electrode is formed in an individual ink pressure chamber. The inkjet printer head according to claim 1 or 2, wherein the inkjet plates are laminated on the cavity plate so as to face each other. 4. The piezoelectric layer inside the laminate has an internal electrode that has a substantially rhombic shape corresponding to the shape of the ink pressure chamber and that is arranged to face each ink pressure chamber. The inkjet printer head according to claim 2 or 3, wherein a through hole that electrically connects the drive electrode and the internal electrode is formed. 5. The ink jet printer head according to claim 4, wherein the through hole is formed in the arrow-shaped land pattern. 6. The ink jet printer head according to claim 4, wherein the through hole electrically connected to the internal electrode is filled with a conductive material.