JP4330374B2 - Piezoelectric actuator and inkjet recording head - Google Patents

Description

【００４６】
表１によれば、Ｚ１／Ｚ０が０．１５以下である試料Ｎｏ．２〜１１では反りが１００μｍ以下、圧電アクチュエータにかかる圧縮応力が６０ＭＰａ以下で、その応力レンジが５ＭＰａ以下となり、インク吐出速度が３ｍ／ｓｅｃ以上、その吐出速度レンジが１．２ｍ／ｓｅｃ以下であった。
特に、全厚みＺ０を６０μｍとした試料Ｎｏ．２〜４、６〜１１では、圧電アクチュエータの変位が大きくなり、インク吐出速度を４ｍ／ｓｅｃ以上にできた。
さらには、共通電極と導体層との厚み差を１μｍ以下とした試料Ｎｏ．２〜４、７〜１１では、反りが９５μｍ以下、圧電アクチュエータにかかる圧縮応力が５５ＭＰａ以下となり、インク吐出速度を５ｍ／ｓｅｃ以上、インク吐出速度レンジを１ｍ／ｓｅｃ以下にできた。
【００４７】
一方、Ｚ１／Ｚ０を０．２とした試料Ｎｏ．１では圧電アクチュエータにかかる圧縮応力が９０ＭＰａで大きな圧縮応力を受けていることが分かった。これにより反りも１３０μｍと大きく、インク吐出速度は２ｍ／ｓｅｃと小さく、インク吐出速度レンジは１．５ｍ／ｓｅｃと大きかった。
【００４８】
【発明の効果】
本発明の圧電アクチュエータによれば、薄型であっても、圧電アクチュエータの厚みに対する共通電極、導電層および個別電極の厚みの比率を小さくすることによって、圧電アクチュエータに発生する圧縮応力が低減され、優れた圧電特性が得られる。
【００４９】
また、本発明の圧電アクチュエータにおいて、共通電極と導体層とが前記したように線対称となるとき、または導体層と共通電極との距離ｔが上記した所定の関係を満足するように各部材を配置し、さらに個別電極と共通電極との面積比率Ｓが所定の関係を満足するときは、圧電セラミック層の表面に個別電極を形成する焼成処理の後に反り変形が生じるのを抑制し、変位部間での変位ばらつきを低減することができる。
【００５０】
上記圧電アクチュエータを使用することにより、優れたインク吐出性能を有するインクジェット記録ヘッドを得ることができる。
【図面の簡単な説明】
【図１】本発明の一実施形態にかかる圧電アクチュエータの構造を示す断面図である。
【図２】図１の圧電アクチュエータを備えたインクジェット記録ヘッドの構造を示す断面図である。
【図３】従来の圧電アクチュエータの構造を示す断面図である。
【符号の説明】
１ 圧電アクチュエータ
２ 振動板
３ 共通電極
４ 圧電セラミック層
５ 個別電極
６ 導体層
７ セラミック層
８ セラミック層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piezoelectric actuator used for positioning and pressurizing various devices by generating a fine displacement, and more particularly to a piezoelectric actuator used for an ink jet recording head and an ink jet recording head including the same.
[0002]
[Prior art]
2. Description of the Related Art In recent years, with the spread of personal computers and the development of multimedia, the use of ink jet printers is rapidly expanding as recording devices that output information to recording media. Such a printer is equipped with an ink jet recording head. As the ink jet recording head, a piezoelectric method is widely used in that the head can be easily reduced in size and thickness and can be printed with high accuracy.
[0003]
As a piezoelectric actuator used for a piezoelectric method and an ink jet recording head provided with the same, for example, those described in Patent Document 1 and Patent Document 2 are known.
[0004]
FIG. 3 is a cross-sectional view showing an example of a conventional piezoelectric actuator. As shown in FIG. 3, in this piezoelectric actuator, a common electrode 52, a piezoelectric ceramic layer 53, and individual electrodes 54 are laminated in this order on a diaphragm 51 in which ceramic layers 56 and 57 are laminated via a conductor layer 55. A plurality of individual electrodes 54 are arranged on the surface of the piezoelectric ceramic layer 53. In this piezoelectric actuator, by applying a voltage between the common electrode 52 and the predetermined individual electrode 54, the piezoelectric ceramic layer 53 immediately below the individual electrode 54 can be displaced. In recent years, attempts have been made to thin the piezoelectric actuator in order to obtain a sufficient displacement at a low voltage.
[0005]
[Patent Document 1]
JP 2002-36568 A [Patent Document 2]
Japanese Patent Laid-Open No. 11-34321
[Problems to be solved by the invention]
However, if the piezoelectric actuator is made thin in order to obtain a sufficient displacement at a low voltage, the piezoelectric characteristics are deteriorated, and the amount of displacement is lowered, so that the performance as a piezoelectric actuator may not be exhibited. Further, when the layer is thinned, the piezoelectric actuator is easily warped, and this warpage causes a variation in internal stress of the piezoelectric actuator, resulting in a variation in the amount of displacement. When such a piezoelectric actuator is applied to an ink jet recording head, the ink ejection performance is significantly reduced.
[0007]
Therefore, a main object of the present invention is to provide a piezoelectric actuator having excellent piezoelectric characteristics even if it is thin, and an ink jet recording head including the same.
Another object of the present invention is to provide a piezoelectric actuator that is suppressed in warping deformation even if it is thin, and an ink jet recording head including the piezoelectric actuator.
[0008]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have found that when the thickness of the piezoelectric actuator is reduced, the ratio of the thickness of the common electrode, conductive layer, and individual electrode to the thickness of the piezoelectric actuator increases. Acquired knowledge that the internal stress (compressive stress) generated in the actuator increases and the displacement of the piezoelectric actuator decreases, and based on this knowledge, the ratio of the thickness of the common electrode, conductive layer and individual electrode to the thickness of the piezoelectric actuator As a result, the inventors have found a new fact that compressive stress generated in the piezoelectric actuator is reduced and excellent piezoelectric characteristics can be obtained, and the present invention has been completed.
[0009]
That is, the piezoelectric actuator of the present invention for solving the above problems, on the diaphragm, the common electrode, the piezoelectric ceramic layers and the individual electrode are laminated in this order, the individual electrodes are arrayed on the surface of the piezoelectric ceramic layer The diaphragm is formed by laminating a pair of ceramic layers formed of the same material as the piezoelectric ceramic layer via a conductor layer, and the diaphragm, the common electrode, the piezoelectric ceramic layer, and the individual electrodes are combined. The thickness Z0 in the stacking direction and the thickness Z1 of the common electrode, the conductor layer, and the individual electrode combined satisfy the relationship (Z1 / Z0) ≦ 0.15.
[0010]
In the present invention, in the cross section in the thickness direction of the piezoelectric actuator, the common electrode and the conductor layer pass through a position that is 1/2 of the total thickness Z of the diaphragm, the common electrode, and the piezoelectric ceramic layer. And it is preferably arranged so as to be line symmetric with respect to a line parallel to the surface of the piezoelectric ceramic layer, so that warping deformation occurs after the firing process of forming individual electrodes on the surface of the piezoelectric ceramic layer. It can suppress and can reduce the dispersion | variation variation between displacement parts.
[0011]
Furthermore, the ratio S (total surface area of the individual electrodes / surface area of the common electrode) of the total surface area of the plurality of individual electrodes and the surface area of the common electrode satisfies the relationship of 0.1 ≦ S ≦ 0.8, Piezoelectric ceramics also when A is located closer to the common electrode than the following position B, and the distance t between the following position A and the following position B and the following total thickness Z satisfy the relationship 0 <t ≦ 0.25Z. It is possible to suppress the occurrence of warping deformation after the baking treatment for forming the individual electrodes on the surface of the layer, and to reduce variation in displacement between the displacement portions.
Position A: Z / 2 position in the thickness direction from the surface of the piezoelectric ceramic layer, where Z is the total thickness of the diaphragm, the common electrode, and the piezoelectric ceramic layer.
Position B: a position separated by T / 2 from the common electrode in the direction of the conductor layer, where T is the distance between the common electrode and the conductor layer.
[0012]
The difference between the thickness of the common electrode and the thickness of the conductor layer in the present invention is preferably 1 μm or less. Thereby, since the warp deformation resulting from this thickness difference can be reduced, it is possible to further suppress the warp deformation of the piezoelectric actuator and further reduce the displacement variation between the displacement portions.
[0013]
Further, when the thickness Z is 100 μm or less, the displacement amount of the piezoelectric actuator can be increased. Thereby, when the piezoelectric actuator is applied to the ink jet recording head, the ink discharge speed can be increased.
[0014]
When the common electrode and the conductor layer are formed of the same material, the firing shrinkage in the piezoelectric actuator is made uniform when firing them simultaneously, and warping deformation due to the difference in firing shrinkage amount is reduced. Can do.
[0015]
When the thickness of the individual electrode is 0.5 μm or less, it is possible to reduce warping deformation caused by arranging the individual electrode asymmetrically in the thickness direction of the piezoelectric actuator (arranged only on one surface of the piezoelectric actuator). it can.
[0016]
The piezoelectric actuator of the present invention is particularly suitable for an ink jet recording head. That is, the ink jet recording head of the present invention has the above piezoelectric actuator in which the positions of the ink flow paths and the individual electrodes are aligned on a flow path member in which a plurality of ink flow paths having ink discharge holes are arranged. It is attached. Since the ink jet recording head of the present invention includes the above piezoelectric actuator, it has excellent ink ejection performance.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a piezoelectric actuator according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing the piezoelectric actuator of the present embodiment.
[0018]
As shown in FIG. 1, in the piezoelectric actuator 1, a common electrode 3, a piezoelectric ceramic layer 4, and individual electrodes 5 are laminated in this order on a diaphragm 2, and the individual electrodes 5 are two-dimensionally formed on the surface of the piezoelectric ceramic layer 4. And a plurality of them are regularly arranged. The diaphragm 2 is formed by laminating a pair of ceramic layers 7 and 8 with the conductor layer 6 interposed therebetween, and suppresses warping deformation after the firing process for forming the individual electrodes 5 on the surface of the piezoelectric ceramic layer 4.
[0019]
The piezoelectric actuator 1 applies a voltage between the individual electrode 5 and the common electrode 3 to generate piezoelectric vibrations at a plurality of displacement parts constituted by the individual electrode 5, the piezoelectric ceramic layer 4, and the common electrode 3. be able to. Moreover, it is preferable that the common electrode 3 and the conductor layer 6 are electrically connected. Thereby, the power loss by the piezoelectric drive of the diaphragm 2 which generate | occur | produces when a displacement part displaces can be reduced.
[0020]
The thickness Z0 in the stacking direction of the diaphragm 2, the common electrode 3, the piezoelectric ceramic layer 4 and the individual electrode 5 and the thickness Z1 of the common electrode 3, the conductor layer 6 and the individual electrode 5 are (Z1 / Z0). It is important to satisfy the relationship of ≦ 0.15, preferably 0.03 ≦ (Z1 / Z0) ≦ 0.12, especially 0.05 ≦ (Z1 / Z0) ≦ 0.1. If (Z1 / Z0) exceeds 0.15, the piezoelectric characteristics of the piezoelectric actuator may be degraded.
[0021]
The total thickness Z of the diaphragm 2, the common electrode 3, and the piezoelectric ceramic layer 4 is not particularly limited, but is preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 60 μm in terms of increasing the amount of displacement of the displacement part. It should be: On the other hand, the lower limit of the total thickness Z is preferably 20 μm or more, more preferably 25 μm or more in order to have a mechanical strength that does not break during handling or operation, and to withstand the applied voltage. More preferably, the thickness is 30 μm or more.
[0022]
The position A at Z / 2 in the thickness direction from the surface of the piezoelectric ceramic layer 4 was separated by T / 2 in the direction from the common electrode 3 to the conductor layer 6 when the distance between the common electrode 3 and the conductor layer 6 was T. It is the same as the position B or located closer to the common electrode 3 than the position B. It is preferable that the distance t between the position A and the position B and the total thickness Z satisfy the relationship of 0 ≦ t ≦ 0.25Z, particularly 0 ≦ t ≦ 0.025Z. When t> 0.25Z, the warpage of the piezoelectric actuator 1 may increase. In the case of t = 0, that is, in the cross section in the thickness direction of the piezoelectric actuator, the common electrode 3 and the conductor layer 6 pass through a position of ½ of the thickness Z and are parallel to the surface of the piezoelectric ceramic layer 4. This is a case where they are arranged so as to be line symmetric with respect to the line.
[0023]
Furthermore, the ratio S (total surface area of the individual electrodes 5 / surface area of the common electrode 3) of the total surface area of the plurality of individual electrodes 5 and the surface area of the common electrode 3 satisfies the relationship of 0.1 ≦ S ≦ 0.8. In particular, the ratio S is more preferably 0.2 to 0.5 because the variation in the amount of displacement is reduced. If S <0.1, the degree of integration of the individual electrodes may be low, and practical performance may not be obtained. On the other hand, when S> 0.8, the area ratio of the individual electrodes becomes too large, and the warpage of the piezoelectric actuator 1 may increase.
[0024]
In the present invention, even when the ratio S is increased and the individual electrodes 5 are highly integrated, the positions of the common electrode 3 and the conductor layer 6 are adjusted so that the distance t and the thickness Z satisfy the above relationship. Accordingly, it is possible to reduce the warpage, increase the maximum displacement amount, reduce the variation in the displacement amount, and function as a high-performance piezoelectric actuator.
[0025]
The thickness of the piezoelectric ceramic layer 4 and the thickness of the ceramic layers 7 and 8 are not particularly limited as long as Z0 and Z1 satisfy the above relationship, and the position A, the position B, and the distance t satisfy the above relationship. In order to make it possible, the thickness is preferably 20 μm or less, more preferably 10 to 10 μm in order to have mechanical strength that does not break during handling or operation, and to withstand the applied voltage. It should be in the range of 20 μm.
[0026]
The thicknesses of the common electrode 3 and the conductor layer 6 are preferably 0.5 μm or more, more preferably 1 μm or more. Thereby, the rigidity of the piezoelectric actuator 1 can be improved and the effect of suppressing warpage deformation can be enhanced. Further, the difference between the thickness of the common electrode 3 and the thickness of the conductor layer 6 is 1 μm or less, preferably 0.5 μm or less. Further, when the thickness of the conductor layer 6 is a and the Young's modulus of the conductor layer 6 is b, it is preferable to satisfy the relationship of 15 × 10 ¹⁵ ≦ b / a ≦ 220 × 10 ¹⁵ . The thickness of the individual electrode 5 is preferably 0.5 μm or less, and more preferably 0.4 μm or less.
[0027]
For the piezoelectric ceramic layer 4, for example, a perovskite crystal structure type piezoelectric material such as a lead zirconate titanate compound (PbZrTiO ₃ -based compound (PZT)), a lead titanate compound, a barium titanate compound, or the like is preferably used. Of these, it is preferable to use the PZT system in that a large displacement can be obtained. The ceramic layers 7 and 8 are made of the same material as that of the piezoelectric ceramic layer 4. Each of the piezoelectric ceramic layer 4 and the ceramic layers 7 and 8 may be composed of one layer or a plurality of layers.
[0028]
As the individual electrode 5, it is preferable to use a metal such as Au, Ag, Cu, Cr, Pd, Pt, or an alloy containing at least one of these as a main component. In particular, it is more preferable to use Au in that it can be obtained.
[0029]
The common electrode 3 and the conductor layer 6 are preferably formed of the same material. As the common electrode 3 and the conductor layer 6, for example, a metal such as Au, Ag, Cu, Cr, Pd, or Pt or an alloy containing at least one of these as a main component is preferably used, which increases adhesion strength. In particular, it is more preferable to add the same material as that of the piezoelectric ceramic layer 4 to the Ag—Pd alloy.
[0030]
Next, a method for manufacturing the piezoelectric actuator 1 of the present invention will be described.
First, a piezoelectric ceramic powder whose main component is the aforementioned lead zirconate titanate compound, lead titanate compound, barium titanate compound or the like is prepared. The average particle size of the piezoelectric ceramic powder is preferably 1 μm or less, particularly 0.7 μm or less, and more preferably 0.6 μm or less. By setting the average particle size of the piezoelectric ceramic powder to 1 μm or less, uniform firing shrinkage during sintering can be obtained, and the homogeneous piezoelectric ceramic layer 4 and ceramic layers 7 and 8 can be obtained. This piezoelectric ceramic powder and an organic binder component are mixed to prepare a slurry for sheet forming. Next, a green sheet is prepared by a general sheet forming method such as a roll coater method, a slit coater method, or a doctor blade method using this forming slurry (forming step).
[0031]
Next, the green sheet obtained in the molding process is pressurized (pressurizing process). A known method can be adopted as the pressurizing method, but a roll pressurizing method, a plane pressurizing method, a hydrostatic pressurizing method, etc. can be used for pressurization because it is easy to obtain a uniform thickness. . Thus, by performing the pressure treatment of the green sheet after forming the sheet, it is possible to increase the density of the sheet and reduce thickness variation and density variation. The pressurizing pressure varies depending on the material composition, the amount of the organic binder, the thickness of the green sheet, and the like, but it is preferable to pressurize at a pressure of 10 to 100 MPa, particularly 20 to 50 MPa, and further 30 to 40 MPa. Here, the thickness variation of each green sheet obtained by the pressing step is 15% or less, particularly 10% or less. The thickness variation of the piezoelectric ceramic layer 4 and the ceramic layers 7 and 8 formed after firing, and those It becomes easy to reduce the thickness variation of the displacement part formed by laminating and prevent warp deformation.
[0032]
Next, using the conductor paste made of the electrode material described above, a metal pattern that becomes the individual electrode 5, the common electrode 3, and the conductor layer 6 after firing is screen-printed on one surface of the green sheet obtained in the pressing step. To form. In this case, it is desirable that the thickness is adjusted to 2 to 5 μm, and the thickness variation (difference between the maximum value and the minimum value) is adjusted to be 1 to 2 μm.
[0033]
Next, the obtained green sheet is laminated | stacked by the structure shown, for example in FIG. 1, and it adhere | attaches and obtains a lamination | stacking molded object (lamination process). In addition, as a method of performing adhesion, a method using an adhesion liquid containing an adhesive component, a method of adhering to an organic binder component in a green sheet by heating, a method of adhering only by pressing, etc. It can be illustrated.
[0034]
The laminated molded body obtained in the laminating step is subjected to removal of organic components in the laminated molded body by a desired degreasing treatment, and then fired at 900 to 1200 ° C. in an oxygen atmosphere, as shown in FIG. A piezoelectric actuator is obtained (firing process). In the firing process for producing the piezoelectric actuator of the present invention, the laminated molded body obtained in the laminating process is stacked in a plurality of stages through a sample base plate made of zirconia or magnesia, and further, this stacked stacked molding is performed. It is desirable to place a weight on the body and fire. By adopting the manufacturing method including such steps, warping deformation of the piezoelectric actuator is suppressed, and a piezoelectric actuator made of a thin sintered body having a thickness of 100 μm or less can be provided.
[0035]
In addition, the individual electrode constituting the piezoelectric actuator of the present invention is not limited to the case of simultaneous firing with the common electrode and the conductor layer as described above, but after firing the laminated molded body including the common electrode and the conductor layer, Can be formed by baking. Also in this case, various metals described above can be suitably used as the metal component.
[0036]
FIG. 2 is a cross-sectional view showing an ink jet recording head provided with the piezoelectric actuator 1 of the present invention. As shown in the figure, this ink jet recording head is configured such that the piezoelectric actuator 1 is placed on a flow path member 25 in which a plurality of ink flow paths 23 having ink discharge holes 27 are arranged. Are attached with the same position.
[0037]
The flow path member 25 is made of a laminated body composed of a plurality of metal foils having a thickness of about 30 to 100 μm. The ink flow path 23, the ink discharge holes 27, the partition walls 21 are formed on each metal foil by etching or punching with a mold. Etc. are formed respectively. Examples of the metal foil used include stainless steel foil, aluminum foil, and molybdenum foil. Such an ink-jet head has a piezoelectric actuator that has excellent piezoelectric characteristics even when it is thin, and has a warp deformation corrected, so that a large ink discharge amount can be obtained and variation in the ink discharge amount can be reduced. can do.
[0038]
As mentioned above, although embodiment of this invention was shown, it cannot be overemphasized that this invention is applicable not only to embodiment mentioned above but what was changed and improved in the range which does not deviate from the summary of this invention. For example, in the above embodiment, the case where one layer of the common electrode is provided has been described, but two or more layers may be provided as necessary. Similarly, two or more conductor layers 6 may be provided.
[0039]
【Example】
The piezoelectric actuators of Sample Nos. 1 to 11 and the ink jet recording head provided with the same were manufactured as follows.
[0040]
First, a slurry is prepared by mixing a predetermined amount of lead zirconate titanate (PZT) powder, a binder, and an organic solvent for dissolving the binder, and a green sheet having a thickness of 15 μm is prepared by a roll coater method using this slurry. Produced.
[0041]
Next, a through hole having a diameter of 100 μm was formed at a desired position of the green sheet by die punching. Thereafter, an electrode pattern to be a common electrode and a conductor layer after firing was formed on the green sheet by a screen printing method using a metal paste made of an Ag—Pd alloy. The through hole was filled with the same metal paste as the electrode pattern.
[0042]
Each obtained green sheet was alternately laminated and adhered so as to have the structure shown in FIG. 1 and Table 1 to obtain a laminated body, and then pressure was applied to further strengthen the adhesion. Thereafter, a maximum temperature of 1000 ° C. After firing with a conductive paste made of Au, a piezoelectric actuator was obtained by forming an individual electrode pattern to be an individual electrode after firing on one surface of the laminate by screen printing and firing at a maximum temperature of 750 ° C. .
[0043]
The internal stress applied to the piezoelectric actuator at this time and its range (maximum value-minimum value) were calculated from the amount of strain using X-ray diffraction. The warpage of the piezoelectric actuator was evaluated over almost the entire surface using a laser displacement meter.
[0044]
Next, using the piezoelectric actuator obtained above, an ink jet recording head as shown in FIG. 2 was produced, and an ink ejection test was performed. First, a plate made of Fe—Cr based metal in which the ink flow path and the ink supply hole are formed by etching and a plate made of Fe—Cr based metal in which the ink discharge hole is formed by the etching method are bonded to each other by thermosetting epoxy resin. A metal member was obtained by bonding with an agent. Next, a thermosetting epoxy adhesive was applied to the ink channel opening surface side of the metal member described above, and the above-described piezoelectric actuator was positioned so that the ink channel and the individual electrodes were aligned to produce an ink jet recording head. .
[0045]
The ink flow path is filled with ink from an ink supply hole (not shown in FIG. 2), a voltage of 30 V is applied, the piezoelectric actuator is driven at a frequency of 10 KHz, and ink droplets are ejected from the ink ejection holes. The droplet discharge speed was measured and evaluated. In the measurement, image processing was performed using a camera having a high-speed strobe photographing device, and the ink droplet ejection speed and its range (maximum value-minimum value) were measured. The results are shown in Table 1.
[Table 1]

[0046]
According to Table 1, the sample No. Z1 / Z0 is 0.15 or less. 2 to 11, the warp was 100 μm or less, the compressive stress applied to the piezoelectric actuator was 60 MPa or less, the stress range was 5 MPa or less, the ink discharge speed was 3 m / sec or more, and the discharge speed range was 1.2 m / sec or less. It was.
In particular, Sample No. with a total thickness Z0 of 60 μm. In 2 to 4 and 6 to 11, the displacement of the piezoelectric actuator was increased, and the ink discharge speed could be 4 m / sec or more.
Furthermore, sample No. 1 having a thickness difference of 1 μm or less between the common electrode and the conductor layer. 2 to 4 and 7 to 11, the warp was 95 μm or less, the compressive stress applied to the piezoelectric actuator was 55 MPa or less, the ink discharge speed was 5 m / sec or more, and the ink discharge speed range was 1 m / sec or less.
[0047]
On the other hand, Sample No. with Z1 / Z0 set to 0.2. In No. 1, it was found that the compressive stress applied to the piezoelectric actuator was 90 MPa and received a large compressive stress. As a result, the warpage was as large as 130 μm, the ink ejection speed was as small as 2 m / sec, and the ink ejection speed range was as large as 1.5 m / sec.
[0048]
【The invention's effect】
According to the piezoelectric actuator of the present invention, even if the piezoelectric actuator is thin, by reducing the ratio of the thickness of the common electrode, conductive layer, and individual electrode to the thickness of the piezoelectric actuator, the compressive stress generated in the piezoelectric actuator is reduced and excellent. Piezoelectric characteristics can be obtained.
[0049]
In the piezoelectric actuator of the present invention, when the common electrode and the conductor layer are axisymmetric as described above, or each member is set so that the distance t between the conductor layer and the common electrode satisfies the above-described predetermined relationship. Further, when the area ratio S between the individual electrode and the common electrode satisfies a predetermined relationship, it is possible to suppress warping deformation after the firing process for forming the individual electrode on the surface of the piezoelectric ceramic layer, It is possible to reduce the variation in displacement between the two.
[0050]
By using the piezoelectric actuator, an ink jet recording head having excellent ink discharge performance can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a structure of a piezoelectric actuator according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing the structure of an ink jet recording head including the piezoelectric actuator of FIG.
FIG. 3 is a cross-sectional view showing the structure of a conventional piezoelectric actuator.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Piezoelectric actuator 2 Diaphragm 3 Common electrode 4 Piezoelectric ceramic layer 5 Individual electrode 6 Conductor layer 7 Ceramic layer 8 Ceramic layer

Claims (8)

On the diaphragm, the common electrode, the piezoelectric ceramic layers and the individual electrode are laminated in this order, the individual electrodes are arrayed on the surface of the piezoelectric ceramic layer, wherein the diaphragm is formed in the piezoelectric ceramic layer of the same material A piezoelectric actuator in which a pair of ceramic layers are stacked via a conductor layer,
The thickness Z0 in the stacking direction of the diaphragm, the common electrode, the piezoelectric ceramic layer, and the individual electrode, and the thickness Z1 of the common electrode, the conductor layer, and the individual electrode are (Z1 / Z0). A piezoelectric actuator satisfying a relationship of ≦ 0.15. The piezoelectric actuator according to claim 1, wherein the common electrode and the conductor layer are electrically connected. In the cross section in the thickness direction of the piezoelectric actuator, the common electrode and the conductor layer pass through a position that is 1/2 of the total thickness Z of the diaphragm, the common electrode, and the piezoelectric ceramic layer, and the surface of the piezoelectric ceramic layer. claim 1 or 2 piezoelectric actuator according are arranged so as to be line-symmetrical with respect to a line parallel to. The ratio S (total surface area of the individual electrodes / surface area of the common electrode) of the total surface area of the plurality of individual electrodes and the surface area of the common electrode satisfies the relationship of 0.1 ≦ S ≦ 0.8,
The following position A is located closer to the common electrode than the following position B,
The piezoelectric actuator according to any one of claims 1 to 3, wherein a distance t between the following position A and the following position B and the following total thickness Z satisfy a relationship of 0 <t≤0.25Z.
Position A: Z / 2 position in the thickness direction from the surface of the piezoelectric ceramic layer, where Z is the total thickness of the diaphragm, the common electrode, and the piezoelectric ceramic layer.
Position B: a position separated by T / 2 from the common electrode in the direction of the conductor layer, where T is the distance between the common electrode and the conductor layer. The piezoelectric actuator according to any one of claims 1-4 difference between the thickness of the thickness of the common electrode and the conductor layer is 1μm or less.   The piezoelectric actuator according to claim 1, wherein the common electrode and the conductor layer are formed of the same material.   The piezoelectric actuator according to claim 1, wherein the individual electrode has a thickness of 0.5 μm or less.   The piezoelectric actuator according to any one of claims 1 to 7 is mounted on a flow path member in which a plurality of ink flow paths having ink discharge holes are arranged with the positions of the ink flow paths and the individual electrodes aligned. An ink jet recording head characterized by the above.

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