JP2005027402A - Piezoelectric actuator and liquid discharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly durable piezoelectric actuator and a liquid discharger which can hardly cause depolarization. <P>SOLUTION: The piezoelectric actuator has a plurality of displacement elements 5 and 57 on a vibrating plate. A heat radiation member 13 is provided to at least a part of the vibrating plates 3 and 55. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００６２】
表１から明らかなように、振動板の少なくとも一部に放熱部材を設けた試料Ｎｏ．２〜１１では、最大変位量を６９ｎｍ以上、変位量のばらつきを１３％以下とすることができた。特に、放熱部材の熱伝導率を１５０Ｗ／ｍＫ以上とした試料Ｎｏ．２〜８、１０、１１では、最大変位量を７２ｎｍ以上、変位量のばらつきを１０％以下にまで低減できた。一方、振動板の少なくとも一部に放熱部材を設けなかった試料Ｎｏ．１では、最大変位量が６６ｎｍと小さく、変位量のばらつきが３０％と高かった。
【００６３】
【発明の効果】
本発明によれば、圧電アクチュエータを構成する振動板の少なくとも一部に放熱部材を設けることにより、変位素子を駆動する際の周波数を大きくしても、圧電アクチュエータの発熱による温度上昇を抑制し、圧電アクチュエータの脱分極による変位量の低下を防止することができ、また耐久性の高い圧電アクチュエータ及び液体吐出装置を提供することができる。
【図面の簡単な説明】
【図１】図１は本実施形態の圧電アクチュエータを示すものであり、（ａ）は平面図、（ｂ）は（ａ）のＸ−Ｘ断面図である。
【図２】図２は、他の圧電アクチュエータを示す概略平面図であり、（ａ）は、本図（ｂ）、（ｃ）の該当箇所を示す圧電アクチュエータの概略平面図、（ｂ）は振動板の周縁部に形成した放熱板を示す概略断面図、（ｃ）は振動板の側面部に形成した放熱板を示す概略断面図である。
【図３】本発明の液体吐出装置の概略断面図である。
【図４】従来の液体吐出装置の構造を示すもので、（ａ）概略断面図、（ｂ）平面図である。
【符号の説明】
１、５１・・・圧電アクチュエータ
３、５５・・・振動板
５、５７・・・変位素子
７・・・・・・共通電極
９、５４・・・圧電セラミック層
１１、５６・・個別電極
１３・・・・・放熱部材
２１、５８・・液体吐出口
２３、５３ａ・液体加圧室
２４、５３ｂ・隔壁[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piezoelectric actuator and a liquid ejecting apparatus, and more particularly to a piezoelectric actuator capable of improving heat dissipation and a droplet ejecting apparatus including the same.
[0002]
[Prior art]
Conventionally, products using piezoelectric ceramics include, for example, piezoelectric actuators, filters, piezoelectric resonators (including oscillators), ultrasonic vibrators, ultrasonic motors, piezoelectric sensors, and the like.
[0003]
Among these, the piezoelectric actuator has a very high response speed with respect to an electric signal of the order of 10 ⁻⁶ seconds. ^Therefore , the piezoelectric actuator is used for positioning of an XY stage of a semiconductor manufacturing apparatus or as an ink jet recording head (liquid ejecting apparatus). Yes.
[0004]
FIG. 4 is a cross-sectional view of the liquid ejection device. As shown in FIG. 4A, for example, the liquid ejection device using the ink jet system is configured such that the piezoelectric actuator 51 is provided on the flow path member 53.
[0005]
In the flow path member 53, a plurality of liquid pressurizing chambers 53 a are partitioned by partition walls 53 b, and the liquid pressurizing chambers 53 a are arranged in parallel so as to contact the piezoelectric actuator 51.
[0006]
In the piezoelectric actuator 51, a piezoelectric ceramic layer 54 is provided on a conductive diaphragm 55 that also serves as a common electrode, and an individual electrode 56 is provided on the upper surface side of the piezoelectric ceramic layer 54.
[0007]
As shown in FIG. 4B, a plurality of individual electrodes 56 are arranged on the surface of the piezoelectric ceramic layer 54, thereby forming displacement elements 57 that are a plurality of piezoelectric displacement portions, and the liquid pressurizing chamber. It arrange | positions so that it may each be located just above 53a.
[0008]
The liquid ejection apparatus configured as described above applies a voltage between the common electrode 55 and the predetermined individual electrode 56 to displace the piezoelectric ceramic layer 54 directly below the individual electrode 56, thereby causing a liquid pressurizing chamber. The liquid in 53a is pressurized and a droplet is discharged from the liquid discharge port 58 opened in the bottom face of the flow path member 53 (for example, patent document 1).
[0009]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-34321
[Problems to be solved by the invention]
However, it is known that the piezoelectric actuator 51 used in such a liquid ejecting apparatus generates heat when the displacement element 57 is displaced. However, the amount of heat generated is increased particularly by an increase in the driving frequency. There was a problem that depolarization occurred in the layer 54 and the amount of displacement decreased and durability deteriorated.
[0011]
Accordingly, an object of the present invention is to provide a piezoelectric actuator that hardly causes depolarization and has high durability, and a liquid ejection apparatus using the piezoelectric actuator.
[0012]
[Means for Solving the Problems]
As a result of intensive studies on the above problems, the present inventor has provided a heat dissipating member on at least a part of the diaphragm constituting the piezoelectric actuator, so that the piezoelectric element can be driven even when the frequency when driving the displacement element is increased. It has been found that the temperature rise due to the heat generation of the actuator can be suppressed, the displacement amount can be prevented from being lowered due to the depolarization of the piezoelectric actuator, and the purpose of providing a highly durable piezoelectric actuator and liquid ejection device can be achieved.
[0013]
That is, the piezoelectric actuator of the present invention is a piezoelectric actuator in which a plurality of displacement elements are provided on a vibration plate, and is characterized in that a heat radiating member is provided on at least a part of the vibration plate.
[0014]
In the piezoelectric actuator, it is desirable that the heat dissipating member is formed in a wider range in a plane direction than a region where the plurality of displacement elements are arranged, and the thermal conductivity is 15 W / mK or more. desirable.
[0015]
In the piezoelectric actuator, the displacement element is preferably formed by sandwiching a piezoelectric ceramic layer between an individual electrode provided on the surface and an internal electrode, and in particular, the density of the displacement element is 50 pieces / cm ² or more. It is desirable to be.
[0016]
The liquid ejection apparatus of the present invention is provided with the above-described piezoelectric actuator, a flexible flat cable connected to at least the individual electrode of the piezoelectric actuator, and a liquid liquid having a liquid ejection port. The liquid liquid and the individual electrode And a flow path member attached to the diaphragm of the lowermost layer of the piezoelectric actuator.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a piezoelectric actuator and a liquid ejection device of the present invention will be described in detail with reference to the drawings. 1A and 1B show a piezoelectric actuator according to the present embodiment, in which FIG. 1A is a plan view and FIG. 1B is a sectional view taken along line XX in FIG.
[0018]
The piezoelectric actuator 1 of the present invention is configured by providing a plurality of displacement elements 5 on a diaphragm 3. In the displacement element 5, a common electrode 7, a piezoelectric ceramic layer 9, and individual electrodes 11 are laminated in this order, and a plurality of two-dimensionally and regularly arranged on the surface of the piezoelectric ceramic layer 9 are configured. And it is important for the diaphragm 3 to provide the heat radiating member 13 at least in part.
[0019]
The heat dissipating member 13 is formed in a wider area than the region where the plurality of displacement elements 5 are arranged in that it easily releases heat from any of the plurality of displacement elements 5 constituting the piezoelectric actuator 1. It is desirable.
[0020]
In addition, the heat dissipating member 13 is preferably disposed closer to the displacement element 5 in terms of facilitating the release of heat from the piezoelectric actuator 1, but for the reason of suppressing warping of the piezoelectric actuator 1, It is desirable that the common electrode 7 constituting the displacement element 5 be arranged substantially symmetrically in the thickness direction. Here, the substantially symmetrical arrangement in the present invention means that the ratio t1 / t2 between the distance t1 from the upper surface of the piezoelectric actuator to the common electrode 7 and the distance t2 from the lower surface to the heat radiation member 13 is 0.8 to 1.2. The case where it is in the range.
[0021]
2A and 2B are schematic plan views showing other piezoelectric actuators, wherein FIG. 2A is a schematic plan view of the piezoelectric actuator showing the corresponding portions of FIGS. 2B and 2C, and FIG. 2B is a peripheral edge of the diaphragm. FIG. 3C is a schematic cross-sectional view showing a heat sink formed on the side surface of the diaphragm, and FIG. As shown in FIG. 2, in the present invention, the heat radiating member 13 may be formed not only on the substantially entire surface of the diaphragm 3 but also at a part of the region as long as desired heat dissipation is obtained. For example, it can also be formed on the peripheral edge or side surface of the diaphragm 3.
[0022]
The thickness of the heat radiating member 13 is preferably 2 μm or more, particularly 5 μm or more, and more preferably 8 μm or more from the viewpoint of improving heat dissipation. From the reason of suppressing warpage, the upper limit is more preferably 20 μm or less, and particularly preferably 10 μm or less.
[0023]
The thermal conductivity of the heat dissipating member 13 is preferably 15 W / mK or higher, particularly 150 W / mK or higher, and more preferably 250 W / mK or higher.
[0024]
Specifically, as such a heat radiating member 13, a metal or alloy such as Ag, Pd, Cu, or Al, or a ceramic such as SiC, AlN, or Al ₂ O ₃ can be suitably used. Among these, Cu is preferable because it has high thermal conductivity and is low in cost. In addition, it is preferable to use Ag, Pd, or an alloy thereof because Ag—Pd is used as the common electrode and firing can be performed in the air at a low manufacturing cost. Furthermore, AlN or Al ₂ O ₃ is preferable in that it has high thermal conductivity and has a thermal expansion coefficient close to PZT.
[0025]
The thickness of the piezoelectric actuator 1 of the present invention indicates the thickness including the diaphragm 3, the common electrode 7, the piezoelectric ceramic layer 9, and the individual electrode 11, and is preferably 100 μm or less. By using such a thin layer, a large displacement can be obtained, and high-efficiency driving can be realized at a low voltage. Therefore, particularly in response to the demand for higher speed and higher accuracy accompanying the recent performance improvement of color printers, the present invention can meet the demand by setting the thickness to 100 μm or less. And it can contribute to the performance enhancement of the liquid discharge apparatus using the same. In particular, in order to further improve the characteristics as the piezoelectric actuator 1, the thickness is preferably 80 μm or less, more preferably 65 μm or less, and more preferably 50 μm or less.
[0026]
In addition, the lower limit value of the thickness of the piezoelectric actuator 1 is preferably 30 μm, more preferably 40 μm in order to have sufficient mechanical strength and prevent breakage during handling and operation.
[0027]
The thickness of the piezoelectric ceramic layer 9 is preferably 20 μm or less from the viewpoint of having a high displacement as described above and a reduction in size and thickness, and has a mechanical strength that does not break during handling or operation. In order to withstand the applied voltage, the thickness is more preferably in the range of 10 to 20 μm.
[0028]
The thickness of the common electrode 7 is 0.5 μm or 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 further enhanced.
[0029]
The piezoelectric ceramic layer 9 constituting the piezoelectric actuator 1 of the present invention has a perovskite crystal structure type such as lead zirconate titanate compound (PbZrTiO ₃ -based compound (PZT)), lead titanate compound, barium titanate compound, etc. A piezoelectric material is preferably used. Of these, it is preferable to use the PZT system in that a large displacement can be obtained.
[0030]
As the diaphragm 3 constituting the piezoelectric actuator 1 of the present invention, various ceramics, metals or composites thereof can be used, but the bonding strength with the piezoelectric ceramic layer 9 is increased and the difference in thermal expansion coefficient is reduced. In view of this, it is desirable to use the same material as the piezoelectric ceramic layer 9 for the diaphragm 3, and in particular, the piezoelectric ceramic layer 9 constituting the displacement element 5 and the diaphragm 3 is formed by simultaneous firing. This is desirable from the standpoint of unifying the vibration modes of both layers and increasing the bonding strength of both layers.
[0031]
Each of the piezoelectric ceramic layers 9 constituting the displacement element 5 and the diaphragm 3 may be composed of one layer, or may be composed of a plurality of layers.
[0032]
In the piezoelectric actuator 1 of the present invention, at least one filler powder selected from the group consisting of SiC, AlN, and Al ₂ O ₃ is added to the diaphragm 3 to be bonded in order to improve the heat dissipation of the heat dissipation member 13. It can also be contained.
[0033]
As the individual electrode 11, it is preferable to use a metal such as Au, Ag, Cu, Cr, Pd, or 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.
[0034]
Similarly to the common electrode 7 and the individual electrode 11, it is preferable to use a metal such as Au, Ag, Cu, Cr, Pd, or Pt, or an alloy containing at least one of these as a main component. In particular, it is more preferable to add the same material as that of the piezoelectric ceramic layer 9 to the Ag—Pd alloy.
[0035]
Next, the manufacturing method of the piezoelectric actuator of this invention is demonstrated.
[0036]
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, more preferably 0.5 μm or less. By setting the average particle size of the piezoelectric ceramic powder to 1 μm or less, uniform firing shrinkage at the time of sintering can be obtained, and a uniform piezoelectric ceramic layer 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).
[0037]
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.
[0038]
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 pressurizing step is 15% or less, particularly 10% or less. The thickness variation of the piezoelectric ceramic layer 9 formed after firing or the lamination thereof are formed. It is easy to reduce the thickness variation of the displacement element 5 and to prevent warping deformation.
[0039]
Next, using the conductive paste made of the electrode material described above, a metal pattern to be the common electrode 7 is formed by screen printing on one surface of the green sheet obtained in the pressing step after firing. In this case, it is desirable to adjust the thickness to be 2 to 5 μm and the thickness variation (or difference) to be 1 to 2 μm.
[0040]
In the present invention, when the piezoelectric ceramic layer 7 is applied to the heat radiating member 13 constituting the piezoelectric actuator 1 as the vibration plate 3, the heat radiating member 13 is interposed on the green sheet that becomes the piezoelectric ceramic layer 7 of the vibration plate 3 after firing. Thus, it is formed by simultaneous firing with a green sheet to be the piezoelectric ceramic layer 9 of the displacement element 5. That is, the paste that becomes the heat radiation member 13 after firing is printed on the green sheet that becomes the piezoelectric ceramic layer 9 after firing. In this case, the paste film to be the heat radiating member 13 is preferably in the form of a flat film in terms of improving heat dissipation, but the paste film is scattered on the green sheet within a range where desired heat dissipation is obtained. May be.
[0041]
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.
[0042]
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. The piezoelectric actuator 1 is obtained (firing process).
[0043]
In the firing step for producing the piezoelectric actuator 1 of the present invention, the laminated molded body obtained in the laminating step is stacked in a plurality of layers through a sample base plate made of zirconia or magnesia, and this stacked layered product is further stacked. It is desirable to place a weight on the molded body and fire it. By adopting the manufacturing method including such steps, the warp deformation of the piezoelectric actuator 1 is suppressed, and the piezoelectric actuator 1 made of a thin sintered body having a thickness of 100 μm or less can be provided.
[0044]
Note that the individual electrode 11 constituting the piezoelectric actuator 1 of the present invention is not limited to the case of simultaneous firing with the common electrode 7 as described above, and the individual electrode 11 is formed after firing the laminated molded body having the common electrode 7 as an inner layer. It can also be formed by baking. Also in this case, various metals described above can be suitably used as the metal component.
[0045]
When the piezoelectric ceramic layer 9 is similarly used for the displacement element 5 and the vibration plate 3, the displacement element 5 and the vibration plate 3 formed by separately firing in advance are bonded together with the heat radiating plate 13 using a bonding agent. It can also be formed.
[0046]
Furthermore, in the method of joining the displacement element 5 and the diaphragm 3 after firing as described above, a ceramic or metal member other than the piezoelectric ceramic layer 9 is used as the diaphragm 3 if the thermal expansion coefficient is close. You can also.
[0047]
Examples of the ceramic in this case include SiC, AlN, and Al ₂ O ₃ , and examples of the metal include W, Mo, and 4-2 alloy.
[0048]
FIG. 3 is a cross-sectional view showing a liquid ejection apparatus provided with the piezoelectric actuator of the present invention. As shown in the figure, this liquid ejection device is provided with a flow path member in which a plurality of liquid pressurizing chambers 23 having liquid ejection ports 21 are arranged via partition walls 24 on the diaphragm 3 side constituting the piezoelectric actuator 1. On the other hand, the liquid pressurizing chamber 23 and the individual electrode 11 are mounted on the same position. On the individual electrode 11 side, a flexible flat cable (not shown) connected to the control circuit is provided.
[0049]
In the piezoelectric actuator 1, the vibration plate 3 is also displaced around the portion that contacts the displacement element 5 in accordance with the piezoelectric vibration, and the volume of the liquid pressurizing chamber 23 is changed. The liquid stored in the pressurizing chamber 23 can be discharged from the liquid discharge port 21.
[0050]
The flow path member 25 is formed of a laminate composed of a plurality of metal foils having a thickness of about 30 to 100 μm, and the liquid pressurizing chamber 23, the liquid discharge port 21, and the partition walls are formed on each metal foil by etching or punching with a mold. 24 etc. are formed respectively. Examples of the metal foil used include stainless steel foil, aluminum foil, and molybdenum foil. Such a liquid ejection apparatus includes the piezoelectric actuator 1 in which the warp deformation is corrected even if it is thin, so that variations in the liquid ejection amount can be reduced.
[0051]
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.
[0052]
For example, in the above embodiment, the case where one layer of the common electrode 7 is provided has been described.
Two or more layers can be provided as required. Similarly, two or more layers of the heat dissipation member 13 may be provided.
[0053]
【Example】
Sample no. 1 to 11 piezoelectric actuators were produced.
[0054]
First, a predetermined amount of PbZrTiO ₃ powder having an average particle size of 0.5 μm, a binder, and an organic solvent for dissolving the binder are mixed to prepare a slurry, and this slurry is used to form a green having a thickness of 25 μm by a roll coater method. A sheet was produced. Next, a predetermined amount of Ag—Pd (mixing ratio is 7: 3 by mass ratio) powder, organic binder and solvent was mixed to prepare a conductive paste.
[0055]
Next, the conductive paste was printed on the surface of the obtained green sheet, and the pattern used as a common electrode after baking was formed.
[0056]
Next, when the above-described green sheet is used as a diaphragm and a heat radiating member is formed on a plurality of piezoelectric ceramic layers obtained by co-firing the green sheets or on the side surfaces of the piezoelectric ceramic layers, Table 1 The components shown were formed by screen printing or shoe coating so as to have the shape shown in the table. The thermal conductivity (W / mK) of the heat radiating member used in this example was 250 for Ag—Pd, 380 for Cu, 15 for Al ₂ O ₃ , 180 for AlN and 150 for SiC.
[0057]
Next, a base laminate in which the number of piezoelectric ceramic layers constituting the displacement element is one layer and the number of piezoelectric ceramic layers constituting the diaphragm is two is formed on the green sheet, and the base laminate is formed. Was cut to form a laminate, and baked at 1000 ° C. for 2 hours in an oxygen atmosphere to form a piezoelectric actuator body. At this time, the thickness of the piezoelectric ceramic layer was 20 μm, and the thickness of the common electrode was 2 μm. The thickness of the heat radiating member was adjusted to the thickness shown in Table 1. Further, the ratio t1 / t2 between the distance t1 from the upper surface of the piezoelectric actuator to the common electrode 7 and the distance t2 from the lower surface to the heat radiating member 13 was set to 1.
[0058]
Next, a metal paste mainly composed of Au was printed on one surface of the piezoelectric actuator main body and baked at 730 ° C. to produce a piezoelectric actuator as shown in FIG. The thickness of the individual electrode was 1 μm. The sample area was 15 mm × 20 mm. The density of the individual electrodes was 50 / cm ² .
[0059]
Thereafter, a polarization process was performed by applying a DC electric field of 3 kV / mm for 15 minutes between the common electrode and the individual electrodes. The displacement of the piezoelectric actuator is up to 1 × 10 ⁹ cycles by applying a DC voltage of 20 V between the common electrode and the individual electrode, and further applying a Sin driving waveform of 0 to +20 V at a room temperature to the piezoelectric actuator at a frequency of 20 kHz. While measuring the amount of displacement at the time of driving, the variation (σ / x) was obtained. The results are shown in Table 1.
[0060]
For comparison, a sample in which a heat radiating member was not formed on at least a part of the diaphragm was prepared and evaluated in the same manner as the sample of the present invention. The results are also shown in Table 1.
[0061]
[Table 1]

[0062]
As is apparent from Table 1, sample No. 1 in which a heat radiating member was provided on at least a part of the diaphragm. 2 to 11, the maximum displacement amount was 69 nm or more, and the variation of the displacement amount was 13% or less. In particular, the sample No. 1 in which the heat conductivity of the heat dissipating member was 150 W / mK or more. In 2-8, 10 and 11, the maximum displacement amount could be reduced to 72 nm or more and the variation in displacement amount could be reduced to 10% or less. On the other hand, Sample No. in which at least a part of the diaphragm was not provided with a heat dissipating member. In No. 1, the maximum displacement amount was as small as 66 nm, and the variation of the displacement amount was as high as 30%.
[0063]
【The invention's effect】
According to the present invention, by providing a heat dissipating member on at least a part of the diaphragm constituting the piezoelectric actuator, even if the frequency when driving the displacement element is increased, the temperature rise due to heat generation of the piezoelectric actuator is suppressed, A decrease in displacement due to depolarization of the piezoelectric actuator can be prevented, and a highly durable piezoelectric actuator and liquid ejection device can be provided.
[Brief description of the drawings]
1A and 1B show a piezoelectric actuator according to an embodiment of the present invention, in which FIG. 1A is a plan view and FIG. 1B is a sectional view taken along line XX in FIG.
FIG. 2 is a schematic plan view showing another piezoelectric actuator, (a) is a schematic plan view of the piezoelectric actuator showing the corresponding part of FIGS. (B) and (c), and (b) is a schematic plan view of the piezoelectric actuator. FIG. 5 is a schematic cross-sectional view showing a heat radiating plate formed on the peripheral portion of the diaphragm, and FIG.
FIG. 3 is a schematic cross-sectional view of a liquid ejection apparatus according to the present invention.
FIGS. 4A and 4B show the structure of a conventional liquid ejection apparatus, where FIG. 4A is a schematic cross-sectional view, and FIG. 4B is a plan view.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 51 ... Piezoelectric actuator 3, 55 ... Diaphragm 5, 57 ... Displacement element 7 ... Common electrode 9, 54 ... Piezoelectric ceramic layer 11, 56 ... Individual electrode 13 ..... Heat dissipation members 21 and 58..Liquid discharge ports 23 and 53a.Liquid pressurizing chambers 24 and 53b.

Claims (6)

A piezoelectric actuator comprising a plurality of displacement elements provided on a vibration plate, wherein a heat radiating member is provided on at least a part of the vibration plate. 2. The piezoelectric actuator according to claim 1, wherein the heat radiating member is formed in a wider range in a planar direction than a region where the plurality of displacement elements are arranged. 3. The piezoelectric actuator according to claim 1, wherein the heat dissipating member has a thermal conductivity of 15 W / mK or more. 4. The piezoelectric actuator according to claim 1, wherein the displacement element comprises a piezoelectric ceramic layer sandwiched between an individual electrode provided on the surface and an internal electrode. 5. The piezoelectric actuator according to claim 1, wherein the displacement element density is 50 / cm ² or more. A liquid pressurization chamber having a piezoelectric actuator according to any one of claims 1 to 5, a flexible flat cable connected to at least the individual electrode of the piezoelectric actuator, and a liquid discharge port is provided. A liquid ejection apparatus comprising: a chamber member and a flow path member attached to the lowermost vibration plate of the piezoelectric actuator so that the positions of the chamber and the individual electrode are aligned.

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