JP2002079670A - Ink jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discharge ink drops straight from an ink discharge hole by preventing a diaphragm from inclining when the diaphragm of a channel member is formed by cutting by a dicing saw or the like, and eliminating a positional deviation between the ink discharge hole and a maximum pressure generation region (central part of a channel). SOLUTION: When a breadth, a height and a pitch of the diaphragm 1 of the channel member 3 which constitutes the ink jet recording head 10 are (a), b and c respectively, bxc/(axa)/10 is made 2 or smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head mounted on an ink jet recording apparatus used for printing characters and images.

[0002]

2. Description of the Related Art In recent years, with the spread of personal computers and the development of multimedia, the use of an ink jet recording apparatus as an image forming apparatus for outputting information to a recording medium has been rapidly expanding.

An ink jet recording head (hereinafter, referred to as a head) mounted on an ink jet recording apparatus includes:
A fine heater is provided in the flow path filled with ink, and the ink is heated and boiled by the heater, the ink in the flow path is pressurized by bubbles generated in the flow path, and ink droplets are discharged from the ink discharge holes. A thermal jet method and a piezoelectric method in which a partition forming a flow path filled with ink is bent and displaced by a piezoelectric element to mechanically pressurize ink in the flow path and discharge ink droplets from ink discharge holes are common. However, among these, the piezoelectric method has the advantages that the durability and the responsiveness are excellent and that the type of ink is not limited because the ink is not directly heated.

As shown in FIG. 6, such a piezoelectric type head has a plurality of partition walls 41 arranged in parallel, and a zirconate titanate forming an ink flow path 42 between the partition walls 41. A flow path member 43 made of piezoelectric ceramics containing lead oxide or the like as a main component, a top plate 45 joined to the top of each partition wall 41 and provided with an ink supply hole 46 for supplying ink to each flow path 42, A nozzle plate 48 provided with an ink discharge hole 47 communicating with each of the flow paths 42 and joined to the negative end of the flow path member 43; In some cases, the driving electrodes 44 were formed along the respective lines (see Japanese Patent Application Laid-Open No. Hei 7-101056).

The other end of the flow path member 43 has a closed structure, and the piezoelectric ceramic constituting the flow path member 43 is polarized in the direction of the arrow in the figure.
Reference numeral 49 denotes a lead line for connecting the driving electrode 44 to an external circuit (not shown) and supplying a signal from the external circuit to the driving electrode 44.

In order to print on a recording medium using the head 50, when a current is applied between driving electrodes 44 formed on both side surfaces of the partition 41, the partition 41 is substantially deformed by shear mode deformation of the piezoelectric ceramic. Because it is bent and displaced in a U shape,
The ink in each flow path 42 is pressurized, and ink droplets are ejected from the ink ejection holes 47.

In order to manufacture the head 50, for example, a diamond abrasive grain called a dicing saw is fixed to a piezoelectric ceramic body mainly composed of lead zirconate titanate or the like which has been polarized in the thickness direction in advance. Rotary blade (hereinafter,
Using a device having a diamond wheel), a plurality of grooves are engraved at equal intervals, and each groove is used as an ink flow path 42, and a wall member 43 is used as a partition wall 41 partitioning the flow path 42. Then, the driving electrodes 4 are formed on both side surfaces of the partition 41 by a film forming means such as an evaporation method or a sputtering method.
4 is applied, and an ink supply hole 46 is formed at the top of the partition wall 41.
And a top plate 45 having an ink ejection hole 4 formed in advance at the open end of the flow path member 43.
7 has been manufactured by joining a nozzle plate 48 having an adhesive 7 with an adhesive.

[0008]

In recent years, as the accuracy and density of the ink jet recording head 50 have increased, the width of the partition wall 41 of the flow path member 43 constituting the head 50 and the pitch of the partition wall 41 have become extremely large. Although it has become smaller, when the grinding process is performed with a dicing saw to form the partition wall 41 and the flow path 42, the partition wall 41 has a small rigidity. As shown in FIG.
As shown in (2), there is a problem that the position between the ink discharge hole 47 and the central portion P of the flow path 4 (the crossing point of the diagonal line when the cross section of the flow path 42 is rectangular) is shifted. there were. Therefore, the partition wall 41 is displaced to
When the ink inside is pressurized, pressure is generated obliquely with respect to the axis of the ink ejection hole 47, so that the ink droplet cannot be ejected straight to the ink ejection hole 47, and The ink landing position has shifted,
It was not possible to print accurate characters and images according to the information.

[0009]

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a flow path member in which a plurality of partition walls at least partially made of piezoelectric ceramic are arranged in parallel, and a flow path for ink is provided between the partition walls. A top plate that is joined to the top of the partition wall and closes each flow path; and a drive electrode is provided on each of both side surfaces of the partition wall. By displacing, the ink in the flow path is pressurized, and in the ink jet recording head that discharges ink droplets from the ink discharge holes communicating with the flow path, the width of the partition is a, the height of the partition is b, the partition is b, Where c is the pitch of b × c /
The value of (a × a) / 10 is set to 2 or less.

Further, in the present invention, the occupied area ratio of the opening portion of the concave portion such as the pore portion or the crystal grain falling portion present on both side surfaces of the partition wall made of the piezoelectric ceramic is 40% or more and 85% or more.
%, More preferably the piezoelectric ceramic has an average crystal particle diameter of 0.6 to 7 μm,
And a four-point bending strength of 70 MPa or more, and a fracture toughness of 0.1 MPa.
It is preferable to use one having 7 MPam ^1/2 or more.

[0011]

Embodiments of the present invention will be described below.

FIG. 1 is a partially cutaway perspective view showing an example of the ink jet recording head of the present invention, and FIGS. 2 (a) and 2 (b).
FIG. 3 is a partial cross-sectional view for explaining the principle of driving the inkjet recording head of the present invention.

In the ink jet recording head 10, a plurality of partition walls 1 are arranged in parallel at equal intervals, and a flow path member 3 made of piezoelectric ceramics is used as an ink flow path 2 between the partition walls 1.
A top plate 5 joined to the top of the partition wall 1 and having an ink supply hole 6 for leading ink to each flow path 2; and a top plate 5 joined to one end side of the flow path member 3, And a nozzle plate 8 having an ink discharge hole 7 communicating with the partition wall 1.
A driving electrode 4 is formed on the upper half of both side surfaces of the substrate along the longitudinal direction. Each partition 1 is polarized in the direction of an arrow in the figure in order to bend in a substantially rectangular shape by shear mode deformation when a current is applied between the driving electrodes 4 on both side surfaces.

The other end of the flow path member 3 has a closed structure, and a driving electrode 4 formed on the partition wall 1 extends beyond the flow path 2 to the rear of the flow path member 3. It is electrically connected to a driving circuit (not shown) via the wiring 9.

In order to manufacture the head 10, first, a piezoelectric ceramic body is prepared for manufacturing the flow path member 3. As the piezoelectric ceramic body, lead zirconate titanate
(PZT-based), piezoelectric magnesium based on lead magnesium niobate (PMN-based), piezoelectric ceramic based on lead nickel niobate (PNN-based), Piezoelectric ceramics or the like in which components are combined can be used.

After the piezoelectric ceramic body is polarized in the thickness direction, a plurality of grooves, one end of which is closed, are arranged at regular intervals by a diamond wheel such as a dicing saw. A flow path member 3 is manufactured in which the flow paths 2 are used and the walls separating the respective flow paths 2 are partition walls 1. At this time, when the width of the partition is a, the height of the partition is b, and the pitch of the partition is c, b × c / (a × a) / 10 is 2
It is important that:

That is, the inventor of the present invention, in developing the head 10, found that the partition wall 2 of the ground flow path member 3 was inclined, and conducted research on the flow path member 3 in which the partition wall 2 has a small inclination. When the layers are overlapped, the reason is not clear, but when the width of the partition is a, the height of the partition is b, and the pitch of the partition is c, b × c / (a × a) / 10 is set to 2 or less. As a result, it has been found that the inclination of the partition wall 1 can be extremely suppressed, and the present invention has been achieved. Therefore, according to the present invention, the displacement between the ink discharge hole 7 and the center of the flow path 2 which is the pressure maximum generation region can be extremely reduced.

To prevent the partition wall 1 from tilting,
It is necessary to reduce the stress acting on the partition 1,
For example, using a rotary blade to which diamond abrasive grains of # 1000 to # 2000 are adhered, the feed speed is 15 mm / sec.
The processing may be performed at a speed of preferably 5 mm / sec or less.

In order to further suppress the inclination of the partition wall 1 and increase the processing speed, the occupied area ratio of the opening portion of the concave portion such as a pore portion or a crystal grain removal portion present on both side surfaces of the partition wall 1 made of piezoelectric ceramics. Is preferably 40% or more and less than 85%.

Here, the partition 1 made of piezoelectric ceramics
The occupied area ratio of the concave opening present on both side surfaces of the image analyzing device refers to the ratio of the total area of the concave opening present in the measuring visual field to the area of the measuring visual field in the image analyzer.

In order to suppress the inclination of the partition 1, the stress acting on the partition 1 can be reduced by reducing the contact area with the diamond wheel. This can be achieved by appropriately providing recess openings such as pores and grain-removing portions. However, if the occupied area ratio of the recess openings is less than 40%, the recess openings on the side surfaces of the partition wall 1 can be achieved. Is small, the contact area with the diamond wheel is large, so the resistance during grinding is too large, the effect of suppressing the inclination of the partition wall 1 is small, and conversely, the occupied area ratio of the recess opening is 85% or more. In this case, the amount of chipping of the partition wall 1 during the grinding process increases, and the displacement between the ink discharge hole 7 and the center of the flow path 2 (the maximum pressure generation region) increases. A.

Further, if the occupied area ratio of the opening of the concave portion formed on the side surface of the partition 1 is set to 40% or more and less than 85%, the contact area with the diamond wheel can be reduced, and the stress acting on the partition 1 can be reduced. Therefore, the rotation speed and feed speed of the diamond wheel can be increased, for example,
The feed speed can be increased to 30 mm / sec, and productivity can be increased. The occupied area ratio of the recess opening formed on the side surface of the partition wall 1 is 40% or more,
The ratio of less than 85% can be obtained by adjusting the pressure at the time of molding in the method of producing the piezoelectric ceramics, the firing temperature, the crystal grain size of the piezoelectric ceramics, and the like.

Further, in order to suppress the inclination of the partition 1, the piezoelectric ceramic forming the partition 1 has an average crystal grain diameter of 0.6 to 7 μm, a four-point bending strength of 70 MPa or more, and a fracture toughness of 0.7 MPa ^1. It is preferable to use those having a ratio of ^{/ 2} or more.

If the average crystal grain size of the piezoelectric ceramic is less than 0.6 μm, the contact area with the diamond wheel becomes large, and the stress applied to the piezoelectric ceramic also becomes large. Conversely, if the average crystal grain size exceeds 7 μm, This is because, when chipping occurs, a large loss occurs, and when a voltage is applied to the driving electrode 4 to displace the partition 1, the displacement amount is greatly reduced.

Further, the piezoelectric ceramic has a four-point bending strength of less than 70 MPa or a fracture toughness of 0.7 MPa
^{When the thickness is} less than ^1/2 , when the partition wall 1 is formed by grinding the piezoelectric ceramic, the partition wall 1 is easily damaged or chipped, the displacement amount of the partition wall 1 is reduced, and the ejection speed of the ink droplets and the like are reduced. This is because the ejection amount is reduced and the ejection of the ink droplets varies.

Next, platinum, gold, palladium, platinum, gold, palladium, A metal film of rhodium, nickel, aluminum or the like or an alloy film mainly composed of platinum-gold, palladium-silver, platinum-palladium or the like is applied, and the upper half of each partition 1 is made of the above-mentioned metal film or alloy film. Lead wires 9 made of the above-mentioned metal film or alloy film are formed on the drive electrode 4 from the end of the flow path 2 to the rear end of the flow path member 3.

Thereafter, the top of each partition 1 is made of an insulating material such as ceramics, glass, silicon or the like.
A top plate 5 having an ink supply hole 6 for introducing ink into the flow path member 3 is joined with an adhesive or glass.
1 is formed by bonding a nozzle plate 8 made of a material such as ceramics, glass, or silicon having ink discharge holes 7 previously drilled at a predetermined pitch to close the open end of the nozzle plate with an adhesive or glass. Can be obtained.

According to the present invention, since the partition wall 1 has almost no inclination, when the nozzle plate 8 is joined, the positional deviation between the ink discharge holes 7 and the center of the flow path 2 which is the region where the maximum pressure is generated. Can be made extremely small.

Next, the driving principle of the ink jet recording head 10 of the present invention shown in FIG. 1 will be described.

First, an ink such as a pigment type oil-based ink, a water-based dye ink, or an ultraviolet curable ink is introduced into each flow path 2 from the ink supply hole 6 as shown in FIG.
As shown in (a), a positive electrode voltage is applied to the driving electrodes 4b and 4c and the driving electrodes 4h and 4i, respectively.
When a negative voltage is applied to a, 4d, 4g, and 4j, partition walls 1
a and the partition 1b are bent toward the flow path 2a,
Since the partition walls 1d and 1e are bent and displaced toward the flow path 2d, the ink filled in the flow paths 2a and 2d can be pressurized and ink droplets can be discharged from the ink discharge holes 7. Next, when the energization to the driving electrodes 4a to 4d and 4g to 4j is cut off, the partition walls 1a, 1b, 1d, and 1e that have been bent and displaced return to their original shapes by the elastic action, and the inside of the flow paths 2a and 2d is closed. As a result of the pressure reduction, the introduction of the ink from the ink supply hole 6 is started, and the driving electrodes 4 a to 4
When voltages are applied in the opposite directions to d, 4g-4j, the partition walls 1a, 1b are bent outwardly with respect to the flow path 2a and the partition walls 1d, 1e are displaced from the flow path 2d as shown in FIG.
, The inside of the flow passages 2a and 2d is further depressurized and filled with ink. When the power supply to the driving electrodes 4a to 4d and 4g to 4j is cut off, the partition walls 1a, 1b, 1d, and 1e that have been bent and displaced.
Is returned to the original shape by the elastic action, and enters a discharge stage of the next ink droplet. By repeating these operations sequentially, the discharge of the ink droplet can be continuously performed. .

According to the present invention, the width of the partition 1 is
a, when the height of the partition 1 is b and the pitch of the partition 1 is c, b
Since xc / (axa) / 10 is set to 2 or less, it is possible to prevent the partition wall 1 from falling down. The displacement from the center can be made extremely small, and if the ink droplet is ejected, the ink droplet can be ejected almost straight with respect to the axis of the ink ejection hole 7. Therefore, the ink can be accurately landed at a predetermined position on the recording medium, and accurate characters and images according to the information can be printed.

By the way, in the head 10 shown in FIG. 1, an example is shown in which the entire flow path member 3 is formed of piezoelectric ceramics. However, only the partition wall 1 may be formed of piezoelectric ceramics. , Like the head shown in FIG.
The nozzle plate 8 in FIG. 1 is a lid plate 18 having no ink discharge holes 7, the top plate 15 is provided with ink discharge holes 17, and the flow path member 13 is provided with ink supply holes 16 communicating with each flow path 12. Alternatively, as in the head shown in FIG. 4, a plurality of grooves are juxtaposed at equal intervals by a dicing saw in a state in which piezoelectric ceramic plates having different polarization directions are attached to each other, so that the grooves are formed in the flow path 22. It is needless to say that a channel member 23 having a partition 21 as a wall partitioning the groove 22 may be used, and it is needless to say that improvements and changes can be made without departing from the scope of the present invention.

[0033]

Embodiments of the present invention will be described below. (Example 1) A plurality of piezoelectric ceramic bodies containing lead zirconate titanate as a main component were prepared, and after polarization treatment in the thickness direction in advance, the width a of the partition 1, the height b of the partition 1, and the pitch of the partition 1 A plurality of grooves were ground with a dicing saw so that c was in the range shown in Table 1, and a flow path member 3 having the grooves as ink flow paths 2 and the partition walls as partition walls 1 was produced.

In the groove processing, grinding was performed at a rotation speed of 25,000 rpm and a feed speed of 10 mm / sec using a rotary blade to which # 1200 diamond abrasive grains were fixed.

Next, Au is formed on the upper half of the side surface of the partition wall 1 of each flow path member 3 along the longitudinal direction thereof by sputtering.
A lead wire 9 made of an Au film was formed on the drive electrode 4 made of a film and from the end of the flow path 2 to the rear end of the flow path member 3.

Thereafter, a top plate 5 made of alumina ceramic having an ink supply hole 6 is joined to the top of the partition wall 1 with an epoxy-based adhesive, and ink is ejected to the open end of the flow path member 3. Each head 10 having the structure shown in FIG. 1 was manufactured by joining a nozzle plate 8 made of a polyimide resin having holes 7 with an epoxy adhesive.

Then, the ink droplets ejected from each of the manufactured heads 10 are landed on a recording medium, the landing positions of the ink droplets, and the respective ink ejections measured by an image processing apparatus connected to a photographing camera. By comparing the pitch between the holes 7, the displacement of the landing position of the ink droplet was calculated. The drive electrode 4 of the partition 1 has a drive frequency of 12
The input of the negative side was set to 0 kHz, a sine wave in a cut state was used, and a voltage of 30 V was applied only to the positive side to discharge ink droplets.

The head 10 is connected to the plurality of ink ejection holes 7.
Is cut in a plane passing through the ink jetting hole 7 and the degree of inclination of the partition wall 1 is photographed by a photographing camera, and the image is analyzed. Region).

The results are as shown in Table 1 and FIG. FIG. 5 is a graph showing the value of b × c / (a × a) / 10 and the degree of misalignment between the ink discharge hole 7 and the center of the flow path 2 (the maximum pressure generation region).

[0040]

[Table 1]

As a result, first, b × c / (a ×
It can be seen that there is a correlation between the value of a) / 10 and the degree of displacement between the ink ejection hole 7 and the center of the flow path 2 (the maximum pressure generation region).

Then, as can be seen from Table 1 and FIG.
If the value of × c / (a × a) / 10 exceeds 2, the displacement between the ink ejection hole 7 and the center of the flow path 2 (maximum pressure generating portion) exceeds ± 2 μm, and the position on the recording medium Of the ink landing position exceeds the required ± 6 μm, which is inappropriate for printing accurate characters and images.

On the other hand, if the value of b × c / (a × a) / 10 is 2 or less, the positional deviation between the ink discharge hole 7 and the center of the flow path 2 (maximum pressure generating portion) becomes ±. 2 μm or less, and the displacement of the ink landing position on the recording medium can be ± 6 μm or less, so that the printing characteristics required for the head 10 are satisfied and accurate characters based on information are satisfied. And the images could be printed and were excellent.

(Example 2) Next, the sample Nos.
An experiment similar to that in Example 1 was performed by changing the occupation area ratio of the opening of the concave portion such as the pore portion or the particle-removing portion existing on the side surface of the partition wall 1 in the head 10 having the dimension and shape of 4.

The results are as shown in Table 2.

[0046]

[Table 2]

As a result, Sample No. As can be seen from 19 to 23, as the occupied area ratio of the recess opening existing on the side surface of the partition wall 1 increases, the positional displacement between the ink ejection hole 7 and the center of the flow path 2 (maximum pressure generating portion). It can be seen that the displacement of the ink landing position on the recording medium can be reduced. Moreover, in forming the flow path 2, the processing speed could be increased. However, the sample No. Like 23,
The occupied area ratio of the opening of the recess existing on the side surface of the partition wall 1 is 85
%, The positional deviation between the ink discharge holes 7 and the center of the flow path 2 (the maximum pressure generating portion) and the positional deviation of the ink landing position on the recording medium become large, and large chipping occurs in the partition wall 1. did.

As a result, it is found that the occupied area ratio of the opening of the concave portion existing on the side surface of the partition wall 1 should be 40% or more and less than 85%.

Example 3 Further, Sample N shown in Table 1
o. In the head 10 having the size and the shape of 4 as shown in FIG.
An experiment similar to that of Example 1 was performed by changing the average crystal grain size, the four-point bending strength, and the fracture toughness value of the piezoelectric ceramics forming the piezoelectric ceramics.

The average crystal grain size of the piezoelectric ceramic forming the partition walls 1 was determined by taking a photograph of the surface or cross section of the sintered body with an SEM (electron microscope), measuring the average crystal grain size by the intercept method, Bending strength is JIS R16
01 and measured in accordance with JIS R160
7 was measured.

The results are as shown in Table 3.

[0052]

[Table 3]

As a result, as shown in Table 3, (b ×
c) / (a × a) / 10 is 2 or less, and the occupied area ratio of the recess opening on the side surface of the partition wall 1 is 40% or more, and 8
Less than 5%, and the average crystal grain size of the piezoelectric ceramic is 0.6 to 7 μm, and the four-point bending strength is 70 MPa.
As described above, when a material having a fracture toughness of 0.7 MPam ^1/2 or more is used, the inclination of the partition wall 1 can be suppressed, and the displacement between the center point of the flow path 2 and the ink ejection hole 7 can be effectively reduced. Can and was excellent.

[0054]

As described above, according to the present invention, a plurality of partition walls at least partially made of piezoelectric ceramic are arranged in parallel, and a flow path member having an ink flow path between each partition wall; A top plate that is joined to the top and closes each flow path; and a drive electrode is provided on each of both side surfaces of the partition wall, and the drive electrode is energized to bend the partition wall into a substantially rectangular shape. In the ink jet recording head that generates a pressure wave in the flow path and discharges ink droplets from ink discharge holes communicating with the flow path, the width of the partition is a, the height of the partition is b, and the pitch of the partition is c. And the value of b × c / (a × a) / 10 is 2
Since it is set as follows, the inclination at the time of forming the partition wall by the grinding process can be suppressed, and the partition wall can be formed perpendicular to the bottom surface of the flow path, so that the positional displacement between the ink ejection hole and the maximum pressure generation region can be reduced. Since the ink droplets can be made extremely small, they can be ejected almost straight to the ink ejection holes by ejecting ink droplets, and the variation in ink landing position on the recording medium can be suppressed to ± 6 μm or less. It can print accurate characters and images that meet the printing characteristics required by the printhead and that are informed of the information.

Further, according to the ink jet recording head of the present invention, the occupied area ratio of the opening of the concave portion such as the pore portion or the grain-removing portion existing on the side surface of the partition wall made of the piezoelectric ceramic is 40%.
% Or more and less than 85%, the inclination of the partition walls during grinding using a diamond wheel can be further suppressed, the processing speed can be increased, and productivity can be improved.

Further, according to the ink jet recording head of the present invention, the average crystal particle diameter is 0.6 to 7 μm, the four-point bending strength is 70 MPa or more, and the fracture toughness value is 0.7 MPa.
By forming the partition wall with a piezoelectric ceramic that is ^1/2 or more, the inclination of the partition wall during grinding using a diamond wheel can be further suppressed, and defects such as breakage of the partition wall and large chipping can be reduced. Further, the processing speed can be increased.

[Brief description of the drawings]

FIG. 1 is a partially broken perspective view showing an example of an ink jet recording head of the present invention.

FIGS. 2A and 2B are partial cross-sectional views for explaining the driving principle of an ink jet recording head according to the present invention.

FIG. 3 is a partially broken perspective view showing another example of the inkjet recording head of the present invention.

FIG. 4 is a perspective view showing still another example of the ink jet recording head of the present invention, in which a portion-is broken.

FIG. 5 is a graph showing a relationship between a value of b × c / (a × a) / 10 and a value of a displacement between an ink ejection hole and a center point of a flow path.

FIG. 6 is a perspective view showing a conventional ink jet recording head, in which a portion-is broken.

FIG. 7 is a cross-sectional view showing one flow path of the ink jet recording head shown in FIG.

[Explanation of symbols]

 1, 11, 21, 41: partition wall 2, 12, 22, 42: flow path 3, 13, 23, 43: flow path member 4, 14, 44: drive electrode 5, 15, 45: top plate 6, 16 , 46: Ink supply holes 7, 17, 47: Ink ejection holes 8, 18, 48: Nozzle plate 9, 19, 49: Wiring 10, 50: Ink jet recording head

Claims (3)

[Claims] A plurality of partition walls at least partially made of piezoelectric ceramics are juxtaposed, a flow path member having an ink flow path between the partition walls, and a ceiling member joined to the top of the partition walls to close each flow path. And a drive electrode on each side surface of the partition wall, and pressurizes the ink in the flow path by applying a current to the drive electrode to bend and displace the partition wall, thereby communicating with the flow path. B × c / (a × a), where the width of the partition is a, the height of the partition is b, and the pitch of the partition is c, in an ink jet recording head that discharges ink droplets from the ink discharge holes to be formed.
An ink jet recording head, wherein the value of / 10 is 2 or less. 2. An occupied area ratio of an opening portion of a concave portion such as a pore portion or a degranulation portion of crystal grains present on both side surfaces of the partition wall made of the piezoelectric ceramic is 40% or more and less than 85%. Item 2. An ink jet recording head according to item 1. 3. The piezoelectric ceramic according to claim 1, wherein the piezoelectric ceramic has an average crystal grain diameter of 0.6 to 7 μm, a four-point bending strength of 70 MPa or more, and a fracture toughness of 0.7 MPam ^1/2 or more. The inkjet recording head according to claim 1.