JP2003154646A - Ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To densely arrange dots and make dots small in an ink jet head adapted to discharge ink inside pressure chambers by piezoelectric actuators. SOLUTION: A width of each of wiring parts 22a and 24a extending in a lengthwise direction of openings of recesses 2 for the pressure chambers at lower and upper electrodes 22 and 24 is set to be d1 which is smaller than 1/3 of an opening width D of the recess 2. The pressure chambers are arranged in a plurality of arrays, and electric contact groups 24b are set outside the end arrays to be wired between adjacent pressure chambers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet head used in an inkjet printer, and more particularly to an inkjet head which ejects ink by a piezoelectric actuator.

[0002]

2. Description of the Related Art Conventionally, an ink jet head for ejecting ink by a piezoelectric actuator is well known, and its structure is, for example, as shown in FIGS. 10 and 11, a supply port 102a for supplying ink and an ink. The head main body 101 is formed with a plurality of pressure chamber recesses 102 having discharge ports 102b for discharging. Each pressure chamber recess 102 of the head body 101
Are opened in a substantially rectangular shape on the upper surface of the head main body 101, and are arranged in a line in the width direction of the pressure chamber recesses 102 at a predetermined interval.

The head body 101 has a recess 10 for each pressure chamber.
2, a pressure chamber component 105 that constitutes the side wall portion, an ink flow channel component 106 that constitutes the bottom wall of each pressure chamber recess 102 and is formed by laminating a plurality of thin plates, and a nozzle plate 113. Has been done. In the ink flow path component 106, a supply ink flow path 107 connected to the supply ports 102a of the pressure chamber recesses 102 and a discharge ink connected to the discharge ports 102b of the pressure chamber recesses 102, respectively. The flow path 108 is formed. Each supply ink flow path 107
Is connected to an ink supply chamber 110 that extends in the direction in which the pressure chamber recesses 102 are arranged. The ink supply chamber 110 is formed in the pressure chamber component 105 and the ink flow channel component 106.
Further, it is connected to an ink supply hole 111 which is connected to an ink tank (not shown). The nozzle plate 113 includes
Nozzle holes 114 connected to the respective ejection ink flow paths 108 are formed.

On the upper surface of the pressure chamber component 105 of the head main body 101, there are provided piezoelectric actuators 121 for closing the pressure chamber recesses 102 of the head main body 101 and forming pressure chambers 103 together with the pressure chamber recesses 102. There is. Each piezoelectric actuator 121 includes a piezoelectric element 123.
A lower electrode 122 provided on a surface (lower surface) of the piezoelectric element 123 on the pressure chamber 103 side, and an upper electrode 124 provided on a side surface (upper surface) of the piezoelectric element 123 opposite to the pressure chamber 103.
And have. The lower electrode 122 also functions as a so-called diaphragm.

Piezoelectric element 1 of each piezoelectric actuator 121
Reference numeral 23 denotes an extension portion 123a extending in the length direction of the opening of the pressure chamber recess 102 from a portion corresponding to the pressure chamber 103, and both electrodes 122 and 124 overlap the extension portion 123a of the piezoelectric element 123. In this state, wiring portions 122a and 124a extending from the portion corresponding to the pressure chamber 103 in the same direction as the extending portion 123a are provided. A driver I for driving each piezoelectric actuator 121 is provided at the tip of the wiring portions 122a, 124a of the electrodes 122, 124.
Electrical contact portions 122b and 124b for connecting to C and the like are provided, respectively. The width of the wiring portions 122a and 124a is set to be substantially the same as the opening width of the pressure chamber recess 102. Further, the width of the extended portion 123a of the piezoelectric element 123 is equal to the width of the wiring portions 122a and 124a of the electrodes 122 and 124.
Is set to be almost the same as the width of.

Then, the lower electrode 122 and the upper electrode 124
When a pulsed voltage is applied between the piezoelectric element 123 and the piezoelectric element 123, the piezoelectric element 123 contracts in the direction perpendicular to the thickness direction, whereas the lower electrode 122 and the upper electrode 124 do not contract. Due to the effect, the portion of the piezoelectric actuator 121 corresponding to the pressure chamber 103 is bent and deformed to the pressure chamber 103 side in a convex shape.
Due to this flexural deformation, a pressure is generated in the pressure chamber 103, and the ink in the pressure chamber 103 is discharged to the outside from the nozzle hole 114 via the discharge port 102b and the discharge ink flow path 108 by this pressure, and dots are formed on the paper surface. It will adhere to the shape. Then, when the pulse voltage falls, the piezoelectric element 1
23 extends to expand the pressure chamber 10 of the piezoelectric actuator 121.
The portion corresponding to No. 3 returns to the original state, and at this time, the pressure chamber 103 is filled with ink from the ink supply chamber 110 via the supply ink flow path 107 and the supply port 102a.

[0007]

By the way, in the case of the conventional ink jet head as described above, if the maximum discharge amount is increased so that the ink having gradation can be discharged, the pressure chamber However, there is a problem that the size of the head becomes so large that the density of the dots cannot be increased and the whole head becomes large. Also, the shape of the pressure chamber is made to be a strip shape in order to increase the dot density as much as possible, but in the case of a strip shape, there is a limit to reducing the pressure chamber partition wall due to the problem of proximity actuator interference, and It was difficult to arrange the density.

Therefore, in recent years, there has been a particular demand for miniaturization, and as one method for satisfying this demand, forming the piezoelectric element and both electrodes in a thin film shape is considered.

However, when the piezoelectric element is formed into a thin film, a minute defect is likely to occur in the piezoelectric element due to foreign matter or the like at the time of film formation, and the defect may lower the withstand voltage of the piezoelectric element and cause dielectric breakdown. There is. In particular, when the width of the wiring part of both electrodes is set to be the same as the opening width of the pressure chamber recess as in the conventional piezoelectric actuator, the area of the extended part of the piezoelectric element in contact with the electrode becomes considerably large, and The rate of occurrence of dielectric breakdown in the installation part increases.

When such dielectric breakdown occurs, the wiring portion of the electrode is disconnected and it becomes impossible to generate an electric field in the portion of the piezoelectric element corresponding to the pressure chamber.

If the width of the wiring portion is the same as the opening width of the pressure chamber recess, it is difficult to arrange the pressure chambers densely to increase the density of the dots, and the ink jet is used. This leads to an increase in the size of the head.

Therefore, an object of the present invention is to provide a technique capable of reducing the size of an ink jet head and increasing the density of dots.

[0013]

In order to solve this problem, an ink jet head of the present invention is provided with a pressure chamber recess having a supply port for supplying ink and a discharge port for discharging ink. Electrodes provided so as to form a pressure chamber together with the head body and the pressure chamber recess by closing the pressure chamber recess, and are provided on the piezoelectric element and the pressure chamber side of the piezoelectric element and on both surfaces on the opposite side of the pressure chamber. An ink-jet head that includes a piezoelectric actuator having: and deforms the piezoelectric actuator so that the volume of the pressure chamber is reduced by applying a voltage to the piezoelectric element via both electrodes, and ejects ink in the pressure chamber from an ejection port. Then, the pressure chamber recess is opened so as to extend in a predetermined direction on one side surface of the head body, and the piezoelectric element of the piezoelectric actuator is
The electrode has an extending portion extending in the length direction of the pressure chamber recess opening from a portion corresponding to the pressure chamber, and both electrodes are overlapped with the extending portion of the piezoelectric element, and from the portion corresponding to the pressure chamber to the pressure chamber. Each having a wiring portion extending in the length direction of the recess portion opening for use, and the width of the wiring portion of at least one of both electrodes is set to be smaller than 1/3 of the maximum width of the recess opening for the pressure chamber. Is.

Thus, by setting the width of the wiring portion of at least one of the electrodes to be smaller than 1/3 of the maximum width of the recess opening for the pressure chamber, the rate of occurrence of dielectric breakdown in the extended portion is significantly reduced. Become. In other words, if the width of the extended portion of the piezoelectric element is set to be substantially the same as the wiring portion of at least one electrode, the proportion of defective portions caused by forming a thin film of the piezoelectric element in the extended portion is reduced. Also, even if the proportion of the defective portion is increased by making the width of the extended portion larger than the wiring portion of at least one electrode, the proportion of the wiring portion of the electrode formed in the portion corresponding to the defective portion. Is small, and it is possible to favorably suppress the occurrence of dielectric breakdown in the extended portion. As a result, even if the piezoelectric element or the electrode is formed in a thin film shape, it is possible to prevent the wiring portion of the electrode from being broken. Further, when a plurality of pressure chambers are provided and the plurality of pressure chambers are arranged side by side in a plurality of rows, a wiring portion can be disposed between the adjacent pressure chambers and the electric contact portions can be gathered at one place. As a result, the pressure chambers can be arranged more densely than in the case where the electric contact portions are provided around the pressure chambers, and the dot density can be increased while the inkjet head is downsized.

In order to solve this problem, the ink jet head of the present invention is a head body having a pressure chamber recess having a supply port for supplying ink and a discharge port for discharging ink. A piezoelectric having a piezoelectric element and a piezoelectric element and electrodes respectively provided on the pressure chamber side of the piezoelectric element and on both surfaces on the opposite side of the pressure chamber from each other. An ink-jet head that includes an actuator and deforms the piezoelectric actuator so that the volume of the pressure chamber is reduced by applying a voltage to the piezoelectric element via both electrodes to eject ink in the pressure chamber from an ejection port. The chambers are arranged in a plurality of two or more rows, and are individually provided for each pressure chamber of the actuator outside the pressure chamber row located at the end of the pressure chamber row. An electric contact group for another electrode is provided, and the wiring connecting the individual electrode of the pressure chamber located inside the end pressure chamber row and the corresponding contact of the electric contact group is adjacent pressure chambers in the end pressure chamber row. It is configured such that a plurality of head surface sides pass through.

That is, the dot density can be increased by arranging the plurality of pressure chambers in two or more rows. However, if the electrical contacts of these individual electrodes are arranged in the vicinity of each pressure chamber, it is not possible to densely arrange the pressure chambers because it is necessary to secure a contact space around the pressure chambers. Will be widely dispersed,
This leads to an increase in the size of the head. Therefore, by utilizing the upper side (head surface side) of the partition wall that separates adjacent pressure chambers as a wiring space, electrical contacts are gathered outside the end pressure chamber row to facilitate wiring to the pressure chambers. Are arranged so as to be densely arranged.

When the head surface side of the partition walls of the adjacent pressure chambers is used as a wiring space, a conductor is arranged in the space via an insulating layer, and the conductor is superposed and connected to the piezoelectric element of the pressure chamber. Can be considered. However, in such a case, a step is formed in the connection portion, which easily causes a disconnection. This tendency becomes particularly noticeable when the conductor is formed into a thin film. Moreover, such connection wiring is generally difficult.

Therefore, the piezoelectric element and the individual electrode are drawn in the same pattern on the surface of the vibrating plate in a state of overlapping each other,
A drive part for distorting the movable part of the movable part constituting each pressure chamber of the vibration plate is formed, and a pressure chamber row located at an end of the plurality of pressure chamber rows from the drive part is formed. Since the conductor portion extending outward is formed, and the conductor portion extending from the driving portion of the pressure chamber located inside the pressure chamber row at the end passes between the adjacent pressure chambers in the pressure chamber row at the end, The step is not generated, and the pattern can be formed by a method of forming the piezoelectric element and the film of the individual electrode material in a laminated state and then simultaneously patterning, which is also advantageous in manufacturing.

Further, in order to solve this problem, the ink jet head of the present invention comprises a head body having a pressure chamber recess having a supply port for supplying ink and a discharge port for discharging ink. It is provided so as to close the pressure chamber recess and configure the pressure chamber together with the pressure chamber recess,
A piezoelectric actuator having a piezoelectric element and an electrode provided on each of the pressure chamber side and the opposite side of the pressure chamber of the piezoelectric element, and applying the voltage to the piezoelectric element via both electrodes causes the piezoelectric actuator to move to the pressure chamber. Is an inkjet head that deforms so that the volume of the pressure chamber is reduced to discharge the ink in the pressure chamber from the discharge port, and the number of rows of the pressure chamber is 4
-10 rows, the dot density in the sub-scanning direction orthogonal to the main scanning direction that can be printed in one pass in the main scanning direction of the head is 3
The configuration is set to 00 dpi or more.

That is, even if it is attempted to arrange as many pressure chambers as possible in a space of a predetermined length, there is a limit to the number of pressure chambers that can be arranged side by side in order to secure a desired pressure chamber volume, and to achieve a dot density of 300 dpi or more. It is necessary to arrange the pressure chambers in a plurality of rows. However, as the number of rows of pressure chambers increases, the head becomes larger accordingly. According to the present invention, if the number of rows of pressure chambers is set to 4 to 10, by suppressing the thickness of the movable portion of the actuator, it is possible to realize a high dot density of 300 dpi or more without increasing the size of the head.

In order to solve this problem, the ink jet head of the present invention has a head body in which a plurality of pressure chamber recesses having a supply port for supplying ink and a discharge port for discharging ink are formed. And the pressure chamber side electrode and the pressure of the piezoelectric element provided on the pressure chamber side surface of the piezoelectric element and the piezoelectric element by closing the respective pressure chamber recesses to form a pressure chamber together with the pressure chamber recess. A piezoelectric actuator having a chamber and an electrode on the side opposite to the pressure chamber provided on the opposite side, and applying a voltage to the piezoelectric element via both electrodes to deform the piezoelectric actuator so that the volume of the pressure chamber is reduced. An ink jet head for ejecting ink in a pressure chamber from an ejection port, wherein each pressure chamber recess of the head body extends in a predetermined direction on one side surface of the head body. In the piezoelectric actuator, only the piezoelectric element and the opposite pressure chamber side electrode of both electrodes are individually provided for the plurality of pressure chambers, and the opposite pressure chamber side electrode is a portion corresponding to each pressure chamber. And wiring portions extending in the length direction of the pressure chamber recess openings from the pressure chamber corresponding portions, and the width of each wiring portion of the counter pressure chamber side electrode is the maximum width of the pressure chamber recess opening. Is smaller than 1/3 of the above.

As a result, disconnection of the wiring portion due to dielectric breakdown of the piezoelectric element can be suppressed as much as possible, pressure chambers can be arranged at a high density, and the ink jet head can be miniaturized. it can. Further, since the piezoelectric element is not individualized, it is possible to reliably support the wiring portion of the counter pressure chamber side electrode and prevent its disconnection.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a head main body having a pressure chamber recess having a supply port for supplying ink and a discharge port for discharging ink, A piezoelectric actuator that is provided so as to close the chamber recess and forms a pressure chamber together with the pressure chamber recess, and that has a piezoelectric element and electrodes provided on the pressure chamber side of the piezoelectric element and on the opposite side of the pressure chamber. An ink jet head for ejecting ink in a pressure chamber from an ejection port by deforming the piezoelectric actuator so that the volume of the pressure chamber is reduced by applying a voltage to the piezoelectric element via both electrodes, The concave portion for opening is formed so as to extend in a predetermined direction on one side surface of the head body, and the piezoelectric element of the piezoelectric actuator is arranged such that the piezoelectric element of the piezoelectric actuator extends from the portion corresponding to the pressure chamber in the length direction of the concave portion opening for the pressure chamber. Both electrodes have wiring portions that extend in the length direction of the pressure chamber recess opening from the portion corresponding to the pressure chamber in a state of being overlapped with the extension portion of the piezoelectric element. An inkjet head in which the width of the wiring portion of at least one of the electrodes is set to be smaller than ⅓ of the maximum width of the pressure chamber recess opening. Even if the piezoelectric element or the electrode is formed in a thin film shape, the wiring of the electrode This has the effect of suppressing disconnection of the parts. Further, the pressure chambers can be arranged more densely than in the case where the electric contact portions are provided around the pressure chambers, and there is an effect that the density of the dots can be increased while the inkjet head is downsized.

According to a second aspect of the present invention, a head main body having a pressure chamber recess having a supply port for supplying ink and a discharge port for discharging ink, and a recess for the pressure chamber are provided. A piezoelectric actuator that is provided so as to block the pressure chamber together with the recess for the pressure chamber, and includes a piezoelectric element and a piezoelectric actuator having an electrode provided on each of the pressure chamber side of the piezoelectric element and the opposite side of the pressure chamber, An inkjet head for ejecting ink in a pressure chamber from an ejection port by deforming a piezoelectric actuator so that the volume of the pressure chamber is reduced by applying a voltage to the piezoelectric element via both electrodes,
The pressure chambers are arranged in a plurality of two or more rows, and an electric power for an individual electrode individually provided for each pressure chamber of the actuator outside the pressure chamber row located at the end of the pressure chamber row. A contact group is provided, and the wiring connecting the individual electrodes of the pressure chambers located inside the pressure chamber row at the end and the corresponding contacts of the electrical contact group is located on the head surface side between the adjacent pressure chambers in the pressure chamber row at the end. Since it is an inkjet head that passes through a plurality of lines, and the upper side (head surface side) of the partition that separates adjacent pressure chambers is used as a wiring space, electrical contacts are collected outside the pressure chamber row at the end and This has the effect of facilitating the wiring and enabling the pressure chambers to be densely arranged. Further, there is an effect that a step is not generated and that the pattern is formed by forming the piezoelectric element and the film of the individual electrode material in a laminated state and then simultaneously patterning, which facilitates the manufacturing.

According to a third aspect of the present invention, there is provided a head main body having a pressure chamber recess having a supply port for supplying ink and an ejection port for discharging ink, and a recess for the pressure chamber. A piezoelectric actuator that is provided so as to block the pressure chamber together with the recess for the pressure chamber, and includes a piezoelectric element and a piezoelectric actuator having an electrode provided on each of the pressure chamber side of the piezoelectric element and the opposite side of the pressure chamber, An inkjet head for ejecting ink in a pressure chamber from an ejection port by deforming a piezoelectric actuator so that the volume of the pressure chamber is reduced by applying a voltage to the piezoelectric element via both electrodes,
An ink jet head in which the number of rows of pressure chambers is 4 to 10 and the dot density in the sub-scanning direction orthogonal to the main scanning direction that can be printed in one pass in the main scanning direction is 300 dpi or more. By suppressing the thickness of the movable portion, it is possible to achieve a high dot density of 300 dpi or more without increasing the size of the head.

According to a fourth aspect of the present invention, there is provided a head main body having a plurality of pressure chamber recesses each having a supply port for supplying ink and a discharge port for discharging ink, and respective pressures. The pressure chamber side electrode provided on the pressure chamber side surface of the piezoelectric element and the piezoelectric element provided on the side opposite to the pressure chamber side electrode provided on the surface of the piezoelectric element and the pressure chamber side of the piezoelectric element. A piezoelectric actuator having an electrode on the side opposite to the pressure chamber provided, and by applying a voltage to the piezoelectric element via both electrodes, the piezoelectric actuator is deformed so that the volume of the pressure chamber is reduced, and ink in the pressure chamber is removed. In an inkjet head for discharging from a discharge port, each pressure chamber recess of the head main body is opened on one side surface of the head main body so as to extend in a predetermined direction, and the piezoelectric actuator is Only the element and the opposite pressure chamber side electrode of both electrodes are individually provided for the plurality of pressure chambers, and the opposite pressure chamber side electrode is a portion corresponding to each pressure chamber and a portion corresponding to each pressure chamber. From each of the pressure chamber recess openings, and the width of each wiring portion of the counter pressure chamber side electrode is set to be smaller than 1/3 of the maximum width of each pressure chamber recess opening. It is an inkjet head that is used, which can prevent disconnection of the wiring part due to dielectric breakdown of the piezoelectric element, can arrange the pressure chambers at high density, and can further downsize the inkjet head. Have an effect. Further, since the piezoelectric elements are not individualized, there is an effect that the wiring portion of the counter pressure chamber side electrode can be reliably supported and its disconnection can be prevented.

FIG. 1 shows an embodiment of the present invention.
9 to 9 will be described. In addition, in these drawings, the same members are denoted by the same reference numerals, and duplicate description is omitted.

(Embodiment 1) FIG. 1 is a plan view showing an ink jet head according to Embodiment 1 of the present invention, and FIG.
Shows a sectional view taken along line II-II of FIG.
The inkjet head includes a head body 1 having a plurality of pressure chamber recesses 2 having a supply port 2a for supplying ink and a discharge port 2b for discharging ink. The pressure chamber recesses 2 of the head body 1 are
The head body 1 is opened in a substantially rectangular shape on one side surface (upper surface), and is arranged in a row at a predetermined interval in the width direction. That is, all the pressure chamber recesses 2 are opened on the upper surface of the head body 1 so as to extend in the left-right direction in FIG. In FIG. 1, only three recesses 2 for the pressure chambers (a nozzle hole 14, a piezoelectric element 23, an upper electrode 24, etc., which will be described later) are shown in order to avoid complication.
In reality, many are provided.

The side wall of each pressure chamber recess 2 of the head body 1 is composed of a pressure chamber component 5 made of silicon or photosensitive glass having a thickness of about 200 μm, and the bottom wall of each pressure chamber recess 2 is The ink flow path component 6 is fixed to the pressure chamber component 5 and is formed by laminating a plurality of stainless steel thin plates.

In the ink flow path component 6, a supply ink flow path 7 connected to the supply port 2a of each pressure chamber recess 2 and a discharge ink flow path 8 connected to the discharge port 2b. Are formed. Each supply ink flow path 7 is connected to an ink supply chamber 10 extending in the direction in which the pressure chamber recesses 2 are arranged. The ink supply chamber 10 is formed in the pressure chamber component 5 and the ink flow channel component 6, and It is connected to an ink supply hole 11 which is connected to an ink tank (not shown).

On the side surface (lower surface) of the ink flow path component 6 opposite to the pressure chamber component 5, an approximately 50 μm thick nozzle plate 13 made of an electroformed plate of stainless steel or Ni or a polymer resin such as polyimide is provided. The nozzle plate 13 has a diameter of about 20 μm which is connected to each of the ejection ink flow paths 8.
Nozzle holes 14 are formed. Each nozzle hole 14
The pressure chamber recesses 2 are arranged on a straight line extending in the arrangement direction.

On the side surface (upper surface) of the pressure chamber component 5 of the head body 1 opposite to the ink flow channel component 6, the pressure chamber recesses 2 of the head body 1 are closed to form the pressure chambers 3 together with the pressure chamber recesses 2. Each of the constituent piezoelectric actuators 21 is provided. Each piezoelectric actuator 21 has a piezoelectric element 23 made of lead zirconate titanate (PZT) having a thickness of 2 to 5 μm, and a Cr having a thickness of 1 to 6 μm provided on the surface (lower surface) of the piezoelectric element 23 on the pressure chamber 3 side. The lower electrode 22 (electrode on the pressure chamber side) and the side surface (upper surface) of the piezoelectric element 23 opposite to the pressure chamber 3
Pt upper electrode 24 (counter pressure chamber side electrode) having a thickness of 0.1 μm. The lower electrode 22 is
It also functions as a so-called diaphragm.

Piezoelectric element 23 of each piezoelectric actuator 21
Has an extending portion 23a extending in the length direction of the opening of the pressure chamber recess 2 from one end of a portion corresponding to the pressure chamber 3 (a portion located directly above the pressure chamber 3). Reference numeral 24 denotes a state in which the piezoelectric element 23 is superposed on the extended portion 23a and extends in the same direction as the extended portion 23a from one end of the portion corresponding to the pressure chamber 3 (the length direction of the opening of the pressure chamber recess 2). It has wiring portions 22a and 24a extending respectively. Each wiring part 22
The electric contact portion 2 for connecting to a driver IC or the like for driving each piezoelectric actuator 21 is provided at the tip end of each of a and 24a.
2b and 24b are provided respectively. Each wiring part 22
The widths of a and 24a and the extended portion 23a of the piezoelectric element 23 are all set to substantially the same d1, and are set to be smaller than 1/3 of the opening width D (maximum width) of the pressure chamber recess 2.

Each piezoelectric actuator 21 applies a voltage to the piezoelectric element 23 through the lower electrode 22 and the upper electrode 24 of the piezoelectric actuator 21 to deform a portion of the piezoelectric actuator 21 corresponding to the pressure chamber 3 to generate a pressure. The ink in the chamber 3 is ejected from the ejection port 2b. That is, when a pulsed voltage is applied between the lower electrode 22 and the upper electrode 24, the rise of the pulse voltage causes the piezoelectric element 23 to contract in the direction perpendicular to the thickness direction thereof, whereas the lower electrode 22 and the upper electrode 24. Since the electrode 24 does not contract, the portion corresponding to the pressure chamber 3 of the piezoelectric actuator 21 is bent and deformed in a convex shape toward the pressure chamber 3 due to the so-called bimetal effect. A pressure is generated in the pressure chamber 3 by this flexural deformation, and the ink in the pressure chamber 3 is ejected by this pressure.
And, it is ejected to the outside from the nozzle hole 14 through the ejection ink flow path 8 and adheres to the paper surface in a dot shape. Then, when the pulse voltage falls, the piezoelectric element 2
3 expands and the portion of the piezoelectric actuator 21 corresponding to the pressure chamber 3 returns to the original state. At this time, the pressure chamber 3 is supplied from the ink supply chamber 10 via the supply ink flow path 7 and the supply port 2a. Ink is filled. Note that not only one color ink but also black ink, cyan ink, magenta ink, and yellow ink may be ejected from different nozzle holes 14 to perform color printing.

Next, a schematic procedure of the method for manufacturing the above-mentioned ink jet head will be described with reference to FIG. Note that, in FIG. 3, the vertical relationship of the inkjet head is reversed from that in FIG. 2.

First, Pt is entirely formed on the single crystal MgO substrate 41.
The film 42 is formed by sputtering (see FIG. 3A), and then the PZT film 43 is formed on the entire Pt film 42 by sputtering (see FIG. 3B). Then, a Cr film 44 is formed on the entire PZT film 43 by sputtering (see FIG. 3C).

Next, the pressure chamber component 5 of the head body 1 is fixed to the upper surface of the Cr film 44 with an adhesive or the like (FIG. 3 (d)).
Then, melt the substrate 41 with hot phosphoric acid, KOH, etc.
It is removed (see FIG. 3 (e)). Subsequently, the ink flow path component 6 and the nozzle plate 1 which are previously integrated on the pressure chamber component 5.
3 is fixed, and the Pt film 42, the PZT film 43, and the Cr film 44 are cut by a dry etching method such as an ion milling method or a reactive ion etching method to be finished into a predetermined shape. The element 23 and the lower electrode 22 are respectively formed (see FIG. 3F). In this way, the inkjet head is completed.

Here, in FIG. 4, the number of defective elements in the lead portion and the number of dielectric breakdown elements in the ink jet head according to the present embodiment are shown in relation to a comparative example. Figure 4 (a)
In Type A, when the width d1 of the wiring portion is larger than the opening width D of the recess for the pressure chamber, Type B is T when the width d1 of the wiring portion is 1/2 of the opening width D of the recess for the pressure chamber,
In the type C, the width d1 of the wiring portion is the opening width D of the recess for the pressure chamber.
1/3 of each case is shown. Also, FIG.
In (b), the number of defective elements in the lead portion and the number of dielectric breakdown elements in the case of Type A, Type B, and Type C are shown. In FIG. 4B, the evaluation parameter is 2000 elements in all cases.

As shown in FIG. 4, the wiring portions 22a, 24a
By setting the width d1 of the extended portion 23a of the piezoelectric element 23 to 1/3 of the opening width D of the pressure chamber recess 2, the width d1 is reduced.
It can be seen that the defect 1 and the dielectric breakdown of the lead portion are remarkably reduced as compared with the case where 1 is the opening width D or more.

As described above, in the first embodiment, the width of the wiring portions 22a and 24a of the lower and upper electrodes 22 and 24 and the extension portion 23a of the piezoelectric element 23 is 1 / the width of the opening of the pressure chamber recess 2. Since it is set to be smaller than 3, the proportion of defective portions due to thin film formation by sputtering in the extended portion 23a of the piezoelectric element 23 is reduced, and the occurrence of dielectric breakdown in the extended portion 23a is improved. Can be suppressed. As a result, even if the piezoelectric element 23 and the electrodes 22 and 24 are formed in a thin film shape, the wiring portion 22 of the electrodes 22 and 24 is formed.
It is possible to suppress disconnection of a and 24a.

When a plurality of pressure chambers 3 are arranged side by side in a plurality of rows as in the third embodiment described later, the wiring portions 22a, 2 extending from the portions corresponding to the pressure chambers 3 in a certain row.
By arranging 4a so as to pass between the pressure chambers 3 adjacent to each other in another row, the electric contact portions 22b and 24b can be gathered at one place. As a result, the electrical contact portion 22
The pressure chambers 3 can be arranged more densely than when b and 24b are provided around the pressure chamber 3, and the ink jet head can be downsized and the density of the nozzle holes 14 can be increased (the density of dots can be increased). You can

In the first embodiment, the wiring portions 22a and 24a of the lower and upper electrodes 22 and 24 and the extension portion 23a of the piezoelectric element 23 have the same width, but the wiring portion 22a of the lower electrode 22 is the same. Or the width of the wiring portion 24a of the upper electrode 24 is less than 1 / of the opening width of the pressure chamber recess 2
It may be set smaller than 3.

In this case, even if the width of the extended portion 23a of the piezoelectric element 23 is increased and the proportion of the defective portion is increased, the wiring portion 22a (24) is formed in the portion corresponding to the defective portion.
The proportion of a) formed is small, and the extension 23
It is possible to favorably suppress the occurrence of dielectric breakdown at a.

(Second Embodiment) FIGS. 5 and 6 show an ink jet head according to a second embodiment of the present invention. Here, the width of the extended portion 23a of the piezoelectric element 23 is set larger than that of the wiring portion 24a of the upper electrode 24.

That is, in the second embodiment, the width of the wiring portion 24a of the upper electrode 24 is the same as in the first embodiment.
Although set to d1 which is smaller than 1/3 of the opening width D of the pressure chamber recess 2, the width of both the extended portion 23a of the piezoelectric element 23 and the wiring portion 22a of the lower electrode 22 is the wiring portion of the upper electrode 24. It is set to d2 larger than 24a (in this second embodiment, larger than 1/3 of the opening width of the pressure chamber recess 2). Further, between the extended portion 23a of the piezoelectric element 23 and the wiring portion 22a of the lower electrode 22, an electric insulating layer 26 made of an electric insulating material (photosensitive polyimide, photoresist, silicon dioxide, etc.) is formed, Piezoelectric element 2
The extended portion 23a of No. 3 and the wiring portion 22a of the lower electrode 22 are electrically insulated.

Therefore, in the second embodiment, since the electrically insulating layer 26 is provided between the extended portion 23a of the piezoelectric element 23 and the wiring portion 22a of the lower electrode 22, the piezoelectric element 2 is formed.
No electric field is generated in the extended portion 23a of the
It is possible to reliably suppress the dielectric breakdown at 3a. Moreover, since the piezoelectric element 23 does not expand and contract in the extension portion 23a, no stress is generated in the portion corresponding to the extension portion 23a on the upper surface of the head body 1, and the head body 1 and the piezoelectric actuator 21 are bonded well. Can be maintained at.

Further, since the width of the extended portion 23a of the piezoelectric element 23 is larger than that of the wiring portion 24a of the upper electrode 24, the upper electrode 24 can be reliably supported. That is, when the extension portion 23a of the piezoelectric element 23 has a small width as in the first embodiment, the supportability of the wiring portion 24a of the upper electrode 24 is insufficient, and moreover, the extension portion 23a of the piezoelectric element 23 is not supported. When formed by etching, the width becomes smaller than the set value due to side etching (undercut), and thus the wiring portion 2
Although disconnection of 4a is likely to occur, in Embodiment 2, since the width of the extended portion 23a of the piezoelectric element 23 is sufficiently large, disconnection of the wiring portion 24a can be prevented.

In the second embodiment, the electrical insulating layer 26 is formed between the extended portion 23a of the piezoelectric element 23 and the wiring portion 22a of the lower electrode 22, but the piezoelectric element is used instead of the electrical insulating layer 26. A similar electric insulating layer 26 may be formed between the extended portion 23a of the piezoelectric element 23 and the wiring portion 24a of the upper electrode 24, and the electric insulating layer 26 may be formed on both sides of the extended portion 23a of the piezoelectric element 23 in the thickness direction. You may form.

Further, in the second embodiment, the wiring portions 22a and 24a of the lower and upper electrodes 22 and 24 and the wiring portion 24a of the upper electrode 24 of the extended portion 23a of the piezoelectric element 23 are used.
However, only the wiring portion 22a of the lower electrode 22 is set to be smaller than 1/3 of the opening width of the pressure chamber recess 2 although only the opening width of the pressure chamber recess 2 is set to be smaller than 1/3 thereof. Alternatively, both wiring portions 22a and 24a may be set smaller than 1/3 of the opening width of the pressure chamber recess 2 as in the first embodiment. The width of the extended portion 23a of the piezoelectric element 23 is
If it is larger than at least one of the two wiring portions 22a and 24a, it may be smaller than 1/3 of the opening width of the pressure chamber recess 2.

Further, the width of the extending portion 23a of the piezoelectric element 23 may be made considerably large so that the extending portions 23a adjacent to each other may be connected to each other. In this case, the lower electrode 2
It is desirable that the two wiring portions 22a also connect mutually adjacent portions to each other.

(Third Embodiment) FIGS. 7 and 8 show an ink jet head according to a third embodiment of the present invention.
Here, the piezoelectric element 23 and the lower electrode 22 are not individually provided for the plurality of pressure chambers 3, and the head body 1
It differs from the first and second embodiments in that it is formed on almost the entire upper surface.

That is, in the third embodiment, only the upper electrode 24 of the lower and upper electrodes 22 and 24 and the piezoelectric element 23 is individually provided for the plurality of pressure chambers 3, and each pressure chamber 3 is provided. Each of the pressure chambers 3 has a corresponding portion and a wiring portion 24a extending in the length direction of each pressure chamber 3 from one end of the corresponding portion of each pressure chamber 3. The width of the wiring portion 24a of the upper electrode 24 is equal to the opening width D of the pressure chamber recess 2
Is set to d1 which is smaller than 1/3 of the above.

The plurality of pressure chambers 3 are arranged side by side in two rows, and the wiring portion 2 extending from the portion of the upper electrode 24 corresponding to the pressure chambers 3 in the first row (the left side row in FIG. 7).
4a is arranged so as to pass between the pressure chambers 3 that are adjacent to each other in the second row (right side row in FIG. 7), and each wiring portion 24
The contact portion 24b of "a" is arranged on one side edge of the upper surface of the head body 1. It should be noted that the lower electrode 22 is provided at a portion corresponding to a corner of the upper surface of the head body 1 of the lower electrode 2.
A contact portion 22b for grounding the whole 2 is provided.

The piezoelectric element 23 and the lower electrode 22 are electrically insulated at the portions of the upper electrode 24 corresponding to the wiring portions 24a. That is, the piezoelectric element 23 and the lower electrode 2
The electrical insulating layer 26 made of an electrical insulating material is formed on the portion directly below each wiring portion 24a between the insulating layer 26 and the wiring portion 24, as in the second embodiment.
Are formed.

The portion of the piezoelectric element 23 corresponding to each pressure chamber 3 is separated from the surroundings by a slit-shaped through hole 23c except the portion corresponding to each wiring portion 24a of the upper electrode 24. The hole 23c is filled with the same electrically insulating material as the electrically insulating layer 26.

A schematic procedure of a method for manufacturing such an ink jet head will be described with reference to FIG.

First, Pt is entirely formed on the single crystal MgO substrate 41.
The film 42 is formed by sputtering (see FIG. 9A), and then the Pt film 42 is cut by a dry etching method to finish (individualize) into a predetermined shape to form the upper electrode 24. (See FIG. 9B).

Subsequently, the substrate 41 having the upper electrode 24 formed thereon
A PZT film 43 is formed on the entire upper surface by sputtering (see FIG. 9C), and then a through hole 23c is formed by a dry etching method to finish the piezoelectric element 23 into a predetermined shape (FIG. 9C). 9 (d)).

Next, the substrate 41 on which the piezoelectric element 23 is formed
An electrically insulating material is spin-coated on the entire upper surface in the case of photosensitive polyimide or photoresist, and an electrically insulating material film 45 is formed by sputtering or vapor deposition in the case of silicon dioxide (see FIG. 9E). At this time, the electrically insulating material is filled in the through hole 23c of the piezoelectric element 23.

Next, the piezoelectric element 23 of the electrically insulating material film 45.
The upper part is patterned by photolithography (in the case of photosensitive polyimide or photoresist, the unexposed part (unnecessary part) is removed with an alkaline solution, and in the case of silicon dioxide, it is unnecessary by fluorine after applying a resist and patterning. By removing the portions to make them individualized), the electrical insulating layer 26 is formed in the portions of the upper electrode 24 corresponding to the wiring portions 24a (see FIG. 9F). At this time, the electrically insulating material in the through hole 23c of the piezoelectric element 23 is not removed but left as it is.

Subsequently, the piezoelectric element 23 or the electric insulating layer 2
A Cr film is formed on the entire 6 (see FIG. 9 (g)). This Cr film becomes the lower electrode 22 as it is. Then, after the pressure chamber component 5 of the head body 1 is fixed on the lower electrode 22, the substrate 41 is melted and removed with hot phosphoric acid, KOH or the like,
Further, the electrically insulating material in the through hole 23c of the piezoelectric element 23 and the portion other than the electrically insulating layer 26 is removed (FIG. 9 (h)).
reference).

Thereafter, the ink flow path component 6 and the nozzle plate 13 which are integrated in advance are fixed onto the pressure chamber component 5, thereby completing the ink jet head.

Therefore, in the third embodiment, only the upper electrode 24 is individually provided for the plurality of pressure chambers 3, and the width of the wiring portion 24a is 1/3 of the opening width of the pressure chamber recess 2. The plurality of pressure chambers 3 are arranged side by side in two rows, and the contact portions 24b of the wiring portions 24a of the upper electrode 24 are concentrated on one side edge portion of the upper surface of the head main body 1 because the pressure chambers 3 are set smaller than the above. Therefore, it is possible to arrange the pressure chambers 3 at high density while reducing the size of the inkjet head.

Further, since the electrically insulating layer 26 is formed between the piezoelectric element 23 and the lower electrode 22 at a portion corresponding to each wiring portion 24a of the upper electrode 24, the piezoelectric layer is formed in the same manner as in the second embodiment. Wiring part 24 due to dielectric breakdown of element 23
It is possible to prevent disconnection of a and the head body 1
It is possible to prevent the occurrence of defective joint between the piezoelectric actuator 21 and the piezoelectric actuator 21.

Further, since the piezoelectric element 23 is not individualized, the upper electrode 24 can be reliably supported as in the second embodiment, and also in this respect, the disconnection of the wiring portion 24a can be prevented. it can.

Further, due to the through hole 23c of the piezoelectric element 23, the deformation amount of the portion of the piezoelectric element 23 corresponding to the pressure chamber 3 is made approximately the same as when the piezoelectric element 23 is individualized like the upper electrode 24. Therefore, the ink droplets can be ejected well. Since the through hole 23c is filled with an electrically insulating material, the lower electrode 22 and the upper electrode 24 are short-circuited due to foreign matter entering the through hole 23c, or the piezoelectric element 23 is dielectrically broken down. Can be prevented.

In the third embodiment, the electrically insulating layer 26
However, the electric insulating layer 26 is not always necessary. Even if the electric insulating layer 26 is omitted, the width of the wiring portion 24a of the upper electrode 24 is set to be smaller than 1/3 of the opening width of the pressure chamber recess 2, so that the piezoelectric element can be formed in the same manner as in the first embodiment. The disconnection of each wiring portion 24a due to the dielectric breakdown of the element 23 can be suppressed very well.

Further, in the third embodiment, the plurality of pressure chambers 3
Are arranged in two rows, but they may be arranged in three or more rows. In this case, when the contact portions 24b of the wiring portions 24a of the upper electrode 24 are concentrated on one side edge portion of the upper surface of the head body 1, two or more wirings are provided between the pressure chambers 3 in the row closest to the contact portions 24b. The wiring portion 2 is to be passed through the portion 24a.
Although the width of 4a is considerably reduced, the piezoelectric element 23 is not individualized like the upper electrode 24, so that the wiring portion 24a
Is maintained.

Here, the number of rows of the pressure chambers 3 is 4 to 10, and the dot density in the sub-scanning direction orthogonal to the main scanning direction, which can be printed in one pass in the main scanning direction of the head, is 300d.
It can be pi or higher.

That is, even if it is attempted to arrange as many pressure chambers as possible in a space of a predetermined length, there is a limit to the number of pressure chambers that can be arranged side by side in order to secure a desired pressure chamber volume, and a dot density of 300 dpi or more can be realized. It is necessary to arrange the pressure chambers in a plurality of rows. However, if the number of rows of the pressure chambers 3 increases, the head becomes larger accordingly. If the number of rows of the pressure chambers 3 is set to 4 to 10, a high dot density of 300 dpi or more can be realized without increasing the size of the head by suppressing the thickness of the movable portion of the actuator.

That is, the number of pressure chambers arranged in a line can be increased by reducing the area of the movable portion. Here, the dot density is, for example, 300 dp
When i becomes 600 dpi, it is necessary to arrange the double pressure chambers 3 in one column by a simple calculation, but when the dot density doubles, it is less than half of the ink ejection amount ejected by each pressure chamber 3, or 1/4 in some cases. It can be suppressed to the following and the area of the movable part is also reduced. Therefore, the number of pressure chambers arranged in one row increases, and it is not necessary to excessively increase the number of pressure chamber rows.

Further, in the third embodiment, the piezoelectric element 23
Although the same electric insulating material as that of the electric insulating layer 26 is filled in the through hole 23c of the above, the material may be different from that of the electric insulating layer 26 or may be filled with nothing.

Further, in the first to third embodiments, the opening shape of the pressure chamber recess 2 of the head body 1 is substantially rectangular, but it may be rectangular, elliptical or oval. The wiring part 24a of the upper electrode 24 may extend from the portion corresponding to the pressure chamber 3 in the length direction (major axis direction) of the pressure chamber recess 2 opening, and The width of the wiring portion 24a may be smaller than 1/3 of the maximum width (short diameter) of the opening of the recess 2.

Furthermore, in the first to third embodiments, the lower electrode 22 also serves as the diaphragm, but the diaphragm may be provided separately.

In addition, various other modifications are possible. For example, the lower electrode 22, the piezoelectric element 23, the upper electrode 24, etc. may be made of materials and thicknesses different from those of the embodiment (for example, The lower electrode 22 is made of Ni or Ti),
It may be formed by another manufacturing method (for example, a CVD method or a sol-gel method). The pressure chamber component 5, the ink flow channel component 6, and the nozzle plate 13 of the head body 1 can also be made of materials and thicknesses different from those of the embodiment.

[0076]

As described above, according to the present invention, the width of the wiring portion extending in the lengthwise direction of the pressure chamber recess opening in at least one of the two electrodes is set to the maximum width of the pressure chamber recess opening of 1
By setting it smaller than / 3, an effective effect of suppressing disconnection of the electrode wiring portion can be obtained.

Further, a plurality of conductors connecting the individual electrodes of the pressure chambers located inside the end pressure chamber row and the corresponding contacts of the electric contact group pass between the adjacent pressure chambers of the pressure chambers. Therefore, the pressure chambers can be arranged densely, and the effective effect that the density of the dots can be increased and the size of the inkjet head can be reduced can be obtained.

[Brief description of drawings]

FIG. 1 is a plan view showing an inkjet head according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is an explanatory diagram showing an outline of a method for manufacturing an inkjet head.

FIG. 4 is an explanatory diagram showing the number of defective elements in the lead portion and the number of dielectric breakdown elements in the inkjet head according to the first embodiment of the present invention in relation to a comparative example.

FIG. 5 is a plan view showing an inkjet head according to a second embodiment of the present invention.

6 is a sectional view taken along line VV of FIG.

FIG. 7 is a plan view showing an inkjet head according to a third embodiment of the present invention.

8 is a sectional view taken along line VII-VII in FIG.

FIG. 9 is an explanatory diagram showing an outline of a method for manufacturing an inkjet head according to a third embodiment.

FIG. 10 is a plan view showing a conventional inkjet head.

11 is a sectional view taken along line XX of FIG.

[Explanation of symbols]

1 head body 2 Recess for pressure chamber 2a Supply port 2b outlet 3 Pressure chamber 21 Piezoelectric actuator 22 Lower electrode 22a wiring part 23 Piezoelectric element 23a extension part 24 Upper electrode 24a wiring part

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Seiji Tomari             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Hidetoshi Tagami             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Kenji Tomita             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 2C057 AF35 AG15 AG16 AG39 AG44                       AG93 AP02 AP32 AP52 AQ02                       AQ06 BA03 BA14

Claims (4)

[Claims] 1. A head main body having a pressure chamber recess having a supply port for supplying ink and an ejection port for discharging ink, and a pressure for pressing the pressure chamber recess together with the pressure chamber recess. A piezoelectric actuator that is provided so as to form a chamber and that has a piezoelectric element and an electrode that is provided on each of the pressure chamber side of the piezoelectric element and the opposite surface of the piezoelectric element from the pressure chamber. An ink jet head for ejecting ink in the pressure chamber from the ejection port by deforming the piezoelectric actuator so that the volume of the pressure chamber is reduced by applying a voltage to the piezoelectric element, wherein the pressure chamber recess is The piezoelectric element of the piezoelectric actuator is opened from one side surface of the head main body so as to extend in a predetermined direction, and the piezoelectric element is pressed from a portion corresponding to the pressure chamber. Has an extending portion extending in the length direction of the recess portion opening, and the electrodes are extended from the portion corresponding to the pressure chamber to the length of the pressure chamber recess opening in a state of being overlapped with the extending portion of the piezoelectric element. An ink jet head having wiring portions extending in the depth direction, wherein the width of the wiring portion in at least one of the electrodes is set to be smaller than 1/3 of the maximum width of the pressure chamber recess opening. . 2. A head body having a pressure chamber recess having a supply port for supplying ink and a discharge port for ejecting ink, and a pressure with the pressure chamber recess for closing the pressure chamber recess. A piezoelectric actuator that is provided so as to form a chamber and that has a piezoelectric element and an electrode that is provided on each of the pressure chamber side of the piezoelectric element and the opposite surface of the piezoelectric element from the pressure chamber. An ink jet head that deforms the piezoelectric actuator so that the volume of the pressure chamber is reduced by applying a voltage to the piezoelectric element to eject ink in the pressure chamber from the ejection port, and the pressure chamber has two rows. A plurality is arranged side by side above, outside the pressure chamber row located at the end of the pressure chamber row,
A group of electric contacts for individual electrodes individually provided for each pressure chamber of the actuator is provided, and correspondence between the individual electrodes of the pressure chambers located inside the pressure chamber row at the end and the electric contact group The ink jet head is characterized in that a plurality of wirings connecting to the contact point pass through the head surface side between adjacent pressure chambers in the pressure chamber row at the end. 3. A head body having a pressure chamber recess having a supply port for supplying ink and a discharge port for ejecting ink, and the pressure chamber recess for closing the pressure chamber together with the pressure chamber recess. A piezoelectric actuator that is provided so as to form a chamber and that has a piezoelectric element and an electrode that is provided on each of the pressure chamber side of the piezoelectric element and the opposite surface of the piezoelectric element from the pressure chamber. An ink jet head for ejecting ink in the pressure chambers from the ejection ports by deforming the piezoelectric actuator so as to reduce the volume of the pressure chambers by applying a voltage to the piezoelectric element, the number of rows of the pressure chambers Is 4 to 10 columns, and the dot density in the sub-scanning direction orthogonal to the main scanning direction that can be printed in one pass in the main scanning direction of the head is 300 dpi or more. Inkjet head to collect. 4. A head body having a plurality of pressure chamber recesses having a supply port for supplying ink and a discharge port for discharging ink, and the pressure chambers for closing the respective pressure chamber recesses. A pressure chamber side electrode provided on the surface of the piezoelectric element on the pressure chamber side of the piezoelectric element and a counter pressure provided on the side surface of the piezoelectric element opposite to the pressure chamber. A piezoelectric actuator having a chamber-side electrode, and by applying a voltage to the piezoelectric element via the both electrodes, the piezoelectric actuator is deformed so that the volume of the pressure chamber is reduced, and ink in the pressure chamber is removed. An ink jet head for ejecting from the ejection port, wherein each pressure chamber recess of the head body is opened so as to extend in a predetermined direction on one side surface of the head body. In the piezoelectric actuator, only the counter pressure chamber side electrode of the piezoelectric element and both electrodes is individually provided for the plurality of pressure chambers, and the counter pressure chamber side electrode corresponds to each of the pressure chambers. A wiring part extending in the length direction of the pressure chamber recess opening from each of the pressure chamber corresponding parts, and the width of each wiring part of the counter pressure chamber side electrode is the pressure chamber recess. An ink jet head characterized by being set to be smaller than 1/3 of the maximum width of the opening.