JP2002111088A - Multilayer piezoelectric actuator - Google Patents
Multilayer piezoelectric actuatorInfo
- Publication number
- JP2002111088A JP2002111088A JP2000296932A JP2000296932A JP2002111088A JP 2002111088 A JP2002111088 A JP 2002111088A JP 2000296932 A JP2000296932 A JP 2000296932A JP 2000296932 A JP2000296932 A JP 2000296932A JP 2002111088 A JP2002111088 A JP 2002111088A
- Authority
- JP
- Japan
- Prior art keywords
- external electrode
- piezoelectric actuator
- actuator
- columnar
- band
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
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Landscapes
- General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、例えば、自動車用
燃料噴射弁、光学装置等の精密位置決め装置や振動防止
用の駆動素子等に用いられる積層型圧電アクチュエータ
に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated piezoelectric actuator used for a precision positioning device such as a fuel injection valve for an automobile, an optical device, and a driving element for preventing vibration.
【０００２】[0002]
【従来技術】従来より、電歪効果を利用して大きな変位
量を得るために、圧電体と内部電極を交互に積層した積
層型圧電アクチュエータが提案されている。積層型圧電
アクチュエータには、同時焼成タイプと、圧電磁器と内
部電極板を交互に積層したスタックタイプの２種類に分
類されており、低電圧化、製造コスト低減の面から考慮
すると、同時焼成タイプの積層型圧電アクチュエータが
薄層化に対して有利であるために、その優位性を示しつ
つある。2. Description of the Related Art Hitherto, in order to obtain a large displacement using an electrostriction effect, a laminated piezoelectric actuator in which piezoelectric bodies and internal electrodes are alternately laminated has been proposed. Multi-layer piezoelectric actuators are classified into two types: co-firing type and stack type in which piezoelectric ceramics and internal electrode plates are alternately laminated. Considering low voltage and lower manufacturing cost, co-firing type Is advantageous in reducing the thickness of the piezoelectric actuator, and is showing its superiority.
【０００３】図４は、従来の積層型圧電アクチュエータ
を示すもので、このアクチュエータでは、圧電体５１と
内部電極５２が交互に積層されて柱状積層体５３が形成
され、その積層方向における最外層は不活性層５５とさ
れている。内部電極５２は、その一方の端部が左右交互
に絶縁体６１で被覆され、その上から帯状外部電極７０
が内部電極５２と左右各々一層おきに導通するように形
成されている。帯状外部電極７０上には、さらにリード
線７６が半田７７により固定されている。FIG. 4 shows a conventional laminated piezoelectric actuator. In this actuator, piezoelectric bodies 51 and internal electrodes 52 are alternately laminated to form a columnar laminated body 53, and the outermost layer in the laminating direction is the outermost layer. The inactive layer 55 is provided. The internal electrode 52 has one end covered with an insulator 61 alternately on the left and right sides.
Are formed so as to be electrically connected to the internal electrode 52 at every other left and right layer. A lead wire 76 is further fixed on the band-shaped external electrode 70 by solder 77.
【０００４】ところで、近年においては、小型の圧電ア
クチュエータで大きな圧力下において大きな変位量を確
保するため、より高い電界を印加し、長期間連続駆動さ
せることが行われている。In recent years, in order to secure a large displacement under a large pressure with a small piezoelectric actuator, a higher electric field is applied and the piezoelectric actuator is driven continuously for a long period of time.
【０００５】[0005]
【発明が解決しようとする課題】しかしながら、従来の
積層型圧電アクチュエータでは、帯状外部電極７０の幅
が短い場合や長い場合があったが、幅が短い場合には、
帯状外部電極７０から内部電極５２に電圧を供給する際
に流れる電流に対して、帯状外部電極７０と内部電極５
２との接合部の抵抗が高いために、該接合部において局
所発熱を起こし、スパークする虞があった。一方、幅が
長い場合には、アクチュエータを高速で駆動させると、
帯状外部電極７０がアクチュエータの振動を阻害し、ア
クチュエータの振動モードに異常を生じ、アクチュエー
タが破損しやすいといった問題が生じていた。However, in the conventional multilayer piezoelectric actuator, the width of the band-shaped external electrode 70 is sometimes short or long.
The current flowing when the voltage is supplied from the band-shaped external electrode 70 to the internal electrode 52 is reduced by the band-shaped external electrode 70 and the internal electrode 5.
Due to the high resistance at the joint with the second member, there is a possibility that local heat is generated at the joint and sparks occur. On the other hand, when the width is long, when the actuator is driven at a high speed,
The band-shaped external electrode 70 hinders the vibration of the actuator, causing an abnormality in the vibration mode of the actuator and causing a problem that the actuator is easily damaged.
【０００６】本発明は、局所発熱やスパークの発生を防
止できるとともに、帯状外部電極による振動阻害を最小
限にできる高信頼性の積層型圧電アクチュエータを提供
することを目的とする。SUMMARY OF THE INVENTION It is an object of the present invention to provide a highly reliable laminated piezoelectric actuator which can prevent local heat generation and spark generation and minimize vibration inhibition by a strip-shaped external electrode.
【０００７】[0007]
【課題を解決するための手段】本発明の積層型圧電アク
チュエータは、複数の圧電体と複数の内部電極とを交互
に積層して形成された柱状積層体と、前記内部電極が一
層おきに交互に接続され、前記柱状積層体の側面に接合
された一対の帯状外部電極とを具備してなる積層型圧電
アクチュエータであって、前記一対の帯状外部電極の合
計幅を、前記柱状積層体の外周長さの５〜３０％とした
ことを特徴とする。According to the present invention, there is provided a laminated piezoelectric actuator comprising: a columnar laminated body formed by alternately laminating a plurality of piezoelectric bodies and a plurality of internal electrodes; And a pair of band-shaped external electrodes joined to a side surface of the columnar laminate, wherein the total width of the pair of band-shaped external electrodes is set to the outer periphery of the columnar laminate. It is characterized in that it is 5 to 30% of the length.
【０００８】本発明の積層型圧電アクチュエータでは、
一対の帯状外部電極の合計幅が、柱状積層体の外周長さ
に対して５〜３０％であるため、外部電極と内部電極の
接合部の抵抗を十分に低くすることができ、局所発熱や
スパークが起こるといった問題を防止できるとともに、
外部電極が振動を阻害することがなく、高信頼性のアク
チュエータを提供することができる。In the laminated piezoelectric actuator of the present invention,
Since the total width of the pair of band-shaped external electrodes is 5 to 30% of the outer peripheral length of the columnar laminate, the resistance of the joint between the external electrode and the internal electrode can be sufficiently reduced, and local heat generation and While preventing problems such as sparks,
It is possible to provide a highly reliable actuator without external electrodes hindering vibration.
【０００９】本発明では、柱状積層体の側面の点対称と
なる位置に、一対の帯状外部電極が接合されていること
が望ましい。この場合には、アクチュエータを高速で駆
動させた場合に生じるアクチュエータの振動モードを外
部電極が阻害する割合が最も少なくなり、耐久性に優れ
たアクチュエータを提供することができる。In the present invention, it is desirable that a pair of band-shaped external electrodes be joined at positions symmetrical with respect to the side surface of the columnar laminate. In this case, the rate at which the external electrode inhibits the vibration mode of the actuator, which is generated when the actuator is driven at a high speed, is minimized, and an actuator having excellent durability can be provided.
【００１０】さらに本発明では、帯状外部電極が、２５
０℃以上の５％重量減少温度を有する樹脂と導電剤とを
含有する導電性接着剤で形成されていることが望まし
い。Further, according to the present invention, the strip-shaped external electrode has 25
It is desirable to be formed of a conductive adhesive containing a resin having a 5% weight loss temperature of 0 ° C. or more and a conductive agent.
【００１１】従来の積層型圧電アクチュエータでは、自
動車用燃料噴射弁等、高温で使用される場合において
は、該導電性接着剤に用いられている樹脂の耐熱性がな
いために該樹脂が硬化し、アクチュエータ駆動中に内部
電極と外部電極が断線し、変位特性が変化するといった
問題があったが、上記した本発明の導電性接着剤を用い
ることにより、高温での使用に際して強い接着力を維持
することが可能となり、高温の使用環境下、高い印加電
界で高速で連続駆動させる場合においても、外部電極と
内部電極が断線することなく高耐久性を備えた積層型圧
電アクチュエータを提供することができる。In a conventional laminated piezoelectric actuator, when used at a high temperature, such as a fuel injection valve for an automobile, the resin used for the conductive adhesive does not have heat resistance, so that the resin hardens. However, there was a problem that the internal electrode and the external electrode were disconnected during driving of the actuator, and the displacement characteristics were changed. However, by using the above-described conductive adhesive of the present invention, a strong adhesive force was maintained when used at a high temperature. It is possible to provide a laminated piezoelectric actuator with high durability without disconnection of the external and internal electrodes even when the device is driven continuously at a high applied electric field at a high speed under a high-temperature use environment. it can.
【００１２】また本発明では、帯状外部電極が、弾性率
２０ＧＰａ以下、伸度１０％以上の導電性接着剤で形成
されていることが望ましい。この場合には、導電性接着
剤と熱膨張の異なる圧電体及び内部電極と接合する際に
おいて発生する応力、及び、アクチュエータを駆動する
ときに生じる応力を導電性接着剤が吸収することがで
き、駆動時に内部電極と外部電極が断線するといった問
題が生じるのを防ぐことができる。In the present invention, it is preferable that the belt-like external electrode is formed of a conductive adhesive having an elastic modulus of 20 GPa or less and an elongation of 10% or more. In this case, the conductive adhesive can absorb the stress generated when joining the piezoelectric body and the internal electrode having different thermal expansions and the internal electrode, and the stress generated when driving the actuator, It is possible to prevent a problem that the internal electrode and the external electrode are disconnected during driving.
【００１３】さらに本発明では、帯状外部電極が、導電
性接着剤と、薄板状またはメッシュ状の導電部材とから
形成されていることが望ましい。この場合には、高温で
の使用環境下、高い印加電界で高速で駆動させる場合に
おいても、外部電極と内部電極が断線することなく高耐
久性を備えた積層型圧電アクチュエータを提供すること
ができる。Further, in the present invention, it is preferable that the strip-shaped external electrode is formed of a conductive adhesive and a thin plate or mesh conductive member. In this case, it is possible to provide a laminated piezoelectric actuator having high durability without disconnection of the external electrode and the internal electrode even when driven at a high speed with a high applied electric field under a use environment at a high temperature. .
【００１４】特に、メッシュ状の導電部材を用いること
により、該導電部材が断線することなく、アクチュエー
タの伸縮に追従することが可能となり、高い印加電界で
高速で駆動させた場合においても、外部電極がアクチュ
エータの振動を阻害することなく、また、外部電極と内
部電極とが断線することなく高耐久性を備えた積層型圧
電アクチュエータを得ることができる。In particular, by using a mesh-shaped conductive member, it is possible to follow the expansion and contraction of the actuator without breaking the conductive member. Thus, a laminated piezoelectric actuator having high durability can be obtained without obstructing the vibration of the actuator and without disconnection between the external electrode and the internal electrode.
【００１５】ここで、導電性接着剤として、２５０℃以
上の５％重量減少温度を有する樹脂と導電剤とを含有す
るか、もしくは弾性率２０ＧＰａ以下、伸度１０％以上
であるものを使用すると、導電性接着剤の耐熱性、応力
吸収性を向上でき、高温での使用環境下、高い印加電界
で高速で駆動させる場合においても、耐久性をさらに向
上できる。Here, as the conductive adhesive, a resin containing a resin having a 5% weight loss temperature of 250 ° C. or more and a conductive agent or having an elastic modulus of 20 GPa or less and an elongation of 10% or more is used. In addition, the heat resistance and the stress absorption of the conductive adhesive can be improved, and the durability can be further improved even when the conductive adhesive is driven at a high speed with a high applied electric field under a use environment at a high temperature.
【００１６】[0016]
【発明の実施の形態】図１は本発明の積層型圧電アクチ
ュエータの一実施例を示すもので、（ａ）は斜視図、
（ｂ）は（ａ）のＡ−Ａ線に沿った断面図、（ｃ）は
（ａ）のＢ−Ｂ線に沿った断面図である。FIG. 1 shows an embodiment of the laminated piezoelectric actuator of the present invention. FIG. 1 (a) is a perspective view,
(B) is a sectional view taken along the line AA of (a), and (c) is a sectional view taken along the line BB of (a).
【００１７】図１に示すように、本発明の積層型圧電ア
クチュエータは、複数の圧電体１と複数の内部電極２と
を交互に積層して成る柱状積層体１ａの側面において、
内部電極２の端部に一層おきに絶縁体３を形成し、絶縁
体３を形成していない内部電極２の端部を一対の帯状外
部電極４の各々に接続し、各外部電極４にリード線６を
接続固定して構成されている。As shown in FIG. 1, the laminated piezoelectric actuator of the present invention has a structure in which a plurality of piezoelectric bodies 1 and a plurality of internal electrodes 2 are alternately laminated on a side surface of a columnar laminated body 1a.
An insulator 3 is formed at every other end of the internal electrode 2, an end of the internal electrode 2 where the insulator 3 is not formed is connected to each of the pair of strip-shaped external electrodes 4, and a lead is connected to each external electrode 4. The wire 6 is connected and fixed.
【００１８】圧電体１は、例えば、チタン酸ジルコン酸
鉛Ｐｂ（Ｚｒ，Ｔｉ）Ｏ3（以下ＰＺＴと略す）或い
は、チタン酸バリウムＢａＴｉＯ3を主成分とする圧電
セラミックス材料等で形成されている。この圧電セラミ
ックスは、その圧電特性を示す圧電歪み定数ｄ33が高い
ものが望ましい。The piezoelectric body 1 is made of, for example, a piezoelectric ceramic material mainly composed of lead zirconate titanate Pb (Zr, Ti) O 3 (hereinafter abbreviated as PZT) or barium titanate BaTiO 3 . . The piezoelectric ceramics are those piezoelectric strain constant d 33 indicating the piezoelectric characteristic is high is preferable.
【００１９】また、圧電体１の厚み、つまり内部電極２
間の距離は５０〜２５０μｍが望ましい。これは、積層
型圧電アクチュエータは電圧を印加してより大きな変位
量を得るために、積層数を増加させる方法がとられる
が、積層数を増加させた場合に圧電体１の厚みが厚すぎ
るとアクチュエータの小型化、低背化ができなくなり、
一方、圧電体１の厚みが薄すぎると絶縁破壊しやすいか
らである。The thickness of the piezoelectric body 1, that is, the internal electrode 2
The distance between them is preferably 50 to 250 μm. This is because, in order to obtain a larger displacement amount by applying a voltage, a method of increasing the number of layers is adopted for the multilayer piezoelectric actuator. However, when the number of layers is increased, if the thickness of the piezoelectric body 1 is too large, Actuator size and height cannot be reduced,
On the other hand, if the thickness of the piezoelectric body 1 is too small, dielectric breakdown is likely to occur.
【００２０】圧電体１の間には内部電極２が配されてい
るが、この内部電極２は銀−パラジウム等の金属材料で
形成されており、各圧電体１に所定の電圧を印加し、圧
電体１に逆圧電効果による変位を起こさせる作用をな
す。An internal electrode 2 is arranged between the piezoelectric bodies 1, and this internal electrode 2 is formed of a metal material such as silver-palladium, and applies a predetermined voltage to each piezoelectric body 1, It acts to cause the piezoelectric body 1 to be displaced by the inverse piezoelectric effect.
【００２１】複数の圧電体１と複数の内部電極２とを交
互に積層して成る柱状積層体１ａは、先ず、ＰＺＴ等の
圧電セラミックスの仮焼粉末と、アクリル系、ブチラー
ル系等の有機高分子から成るバインダーと、ＤＢＰ（フ
タル酸ジオチル）、ＤＯＰ（フタル酸ジブチル）等の可
塑剤とを混合してスラリーを作製し、該スラリーを周知
のドクターブレード法やカレンダーロール法等のテープ
成型法により圧電体１となるセラミックグリーンシート
を作製する。A columnar laminated body 1a formed by alternately laminating a plurality of piezoelectric bodies 1 and a plurality of internal electrodes 2 is composed of a calcined powder of a piezoelectric ceramic such as PZT and an organic powder such as an acrylic or butyral based. A binder made of molecules and a plasticizer such as DBP (dityl phthalate) and DOP (dibutyl phthalate) are mixed to prepare a slurry, and the slurry is tape-formed by a well-known doctor blade method, calender roll method, or the like. Thereby, a ceramic green sheet to be the piezoelectric body 1 is produced.
【００２２】次に、銀−パラジウム粉末にバインダー、
可塑剤等を添加混合して導電性ペーストを作製し、これ
を前記各グリーンシートの上面にスクリーン印刷等によ
って１〜４０μｍの厚みに印刷する。Next, a binder is added to the silver-palladium powder,
A conductive paste is prepared by adding and mixing a plasticizer and the like, and this is printed on the upper surface of each green sheet to a thickness of 1 to 40 μm by screen printing or the like.
【００２３】そして、最後に上面に導電性ペーストが印
刷されたグリーンシートを積層し、この積層体について
所定の温度で脱バインダーを行った後、９００〜１２０
０℃で焼成することによって作製される。Finally, a green sheet having a conductive paste printed on the upper surface is laminated, and the laminated body is subjected to binder removal at a predetermined temperature.
It is produced by firing at 0 ° C.
【００２４】さらに、柱状積層体１ａのすべての側面に
は、内部電極２が露出しているが、少なくとも一つの側
面において、内部電極２の端部を含む圧電体１の端面に
一層おきに深さ５０〜５００μｍ、積層方向の幅３０〜
２００μｍの溝が形成されており、該溝内にガラス、エ
ポキシ樹脂、ポリイミド樹脂、ポリアミドイミド樹脂、
シリコーンゴム等の絶縁体３が充填されている。Further, the internal electrodes 2 are exposed on all side surfaces of the columnar laminated body 1a, but at least one side surface is deeper than the end surface of the piezoelectric body 1 including the end of the internal electrode 2. 50-500 μm, width 30- in lamination direction
A groove of 200 μm is formed, and glass, epoxy resin, polyimide resin, polyamideimide resin,
An insulator 3 such as silicone rubber is filled.
【００２５】この絶縁体３により、柱状積層体１ａの側
面において、内部電極２の端部が互い違いに一層おきに
絶縁され、内部電極２の絶縁されていない他方の端部は
後述する柱状積層体１ａの側面に形成される正極及び負
極を成す一対の帯状外部電極４に接続されている。The insulator 3 alternately insulates the ends of the internal electrodes 2 alternately on the side surfaces of the columnar laminated body 1a, and the other uninsulated end of the internal electrode 2 is a columnar laminated body described later. It is connected to a pair of band-shaped external electrodes 4 forming a positive electrode and a negative electrode formed on the side surface of 1a.
【００２６】なお、絶縁体３は、柱状積層体１ａとの接
合を強固とするために、柱状積層体１ａの変位に対して
追従する弾性率が低い材料、具体的にはシリコーンゴム
等からなることが好適である。The insulator 3 is made of a material having a low elastic modulus that follows the displacement of the columnar laminated body 1a, specifically, silicone rubber or the like, in order to strengthen the bonding with the columnar laminated body 1a. Is preferred.
【００２７】積層体１ａの側面には一対の帯状外部電極
４が被着形成されており、該帯状外部電極４には、積層
されている内部電極２が一層おきに電気的に接続されて
いる。この帯状外部電極４はそれに接続されている各内
部電極２に圧電体１を逆圧電効果により変位させるに必
要な電圧を共通に供給する作用をなす。A pair of strip-shaped external electrodes 4 are formed on the side surface of the laminate 1a, and the stacked internal electrodes 2 are electrically connected to every other layer. . The band-shaped external electrode 4 functions to commonly supply a voltage necessary for displacing the piezoelectric body 1 by the inverse piezoelectric effect to each internal electrode 2 connected thereto.
【００２８】さらに、帯状外部電極４にはリード線６が
半田７により接続固定されている。このリード線６は帯
状外部電極４を外部の電圧供給部に接続する作用をな
す。Further, a lead wire 6 is connected and fixed to the belt-shaped external electrode 4 by solder 7. The lead wire 6 serves to connect the strip-shaped external electrode 4 to an external voltage supply unit.
【００２９】そして、本発明の積層型圧電アクチュエー
タでは、一対の帯状外部電極４の合計幅が、柱状積層体
１ａの外周長さに対して５〜３０％とされている。即
ち、図１（ｃ）に示すように、一対の帯状外部電極４の
幅をｘとし、柱状積層体１ａの横断面が辺の長さが
Ｌ1、Ｌ2の矩形状である場合には、帯状外部電極４の合
計幅が２ｘ、柱状積層体１ａの外周長さが２Ｌ1＋２Ｌ2
となり、２ｘ／（２Ｌ1＋２Ｌ2）が０．０５〜０．３と
されている。In the laminated piezoelectric actuator of the present invention, the total width of the pair of band-shaped external electrodes 4 is set to 5 to 30% with respect to the outer peripheral length of the columnar laminated body 1a. That is, as shown in FIG. 1C, when the width of the pair of band-shaped external electrodes 4 is x, and the cross-section of the columnar laminate 1a is rectangular with sides of length L 1 and L 2. , The total width of the band-shaped external electrodes 4 is 2x, and the outer peripheral length of the columnar laminate 1a is 2L 1 + 2L 2
Next, 2x / (2L 1 + 2L 2) is 0.05 to 0.3.
【００３０】言い換えれば、柱状積層体１ａの積層方向
に垂直な断面において、帯状外部電極４と柱状積層体１
ａとの接合部長さは、柱状積層体１ａ断面の外周長さの
５〜３０％になるように形成されている。In other words, in the cross section perpendicular to the laminating direction of the columnar laminate 1a, the band-shaped external electrode 4 and the columnar laminate 1a
The length of the joint with a is 5 to 30% of the outer peripheral length of the cross section of the columnar laminate 1a.
【００３１】ここで、一対の帯状外部電極４の合計幅
を、柱状積層体１ａの外周長さに対して５〜３０％とし
たのは、帯状外部電極４の合計幅が、柱状積層体１ａの
外周長さに対して５％より短い場合には、帯状外部電極
４から内部電極２に電圧を供給する際に流れる電流に対
して、帯状外部電極４と内部電極２との接合部の抵抗が
高いために、該接合部において局所発熱を起こし、スパ
ークするといった問題が生じるからである。Here, the reason why the total width of the pair of band-shaped external electrodes 4 is set to 5 to 30% with respect to the outer peripheral length of the columnar laminated body 1a is that the total width of the band-shaped external electrodes 4 is the columnar laminated body 1a. Is smaller than 5% with respect to the outer peripheral length of the external electrode 4, the current flowing when the voltage is supplied from the external band-shaped electrode 4 to the internal electrode 2 is reduced by the resistance of the junction between the external band-shaped external electrode 4 and the internal electrode 2. This is because, due to the high ratio, local heat is generated at the joint, and a problem such as sparking occurs.
【００３２】また、帯状外部電極４の合計幅が、柱状積
層体１ａの外周長さに対して３０％より大きい場合に
は、アクチュエータを高速で駆動させる場合において、
積層方向と垂直な方向の幅の広い帯状外部電極４がアク
チュエータの振動を阻害し、アクチュエータが破損する
といった問題が生じるからである。When the total width of the band-shaped external electrodes 4 is larger than 30% of the outer peripheral length of the columnar laminated body 1a, when the actuator is driven at a high speed,
The reason is that the band-shaped external electrode 4 having a large width in the direction perpendicular to the laminating direction inhibits the vibration of the actuator and causes a problem that the actuator is damaged.
【００３３】帯状外部電極４の合計幅は、柱状積層体１
ａの外周長さに対して、低抵抗を満足し、且つアクチュ
エータの振動を阻害しないという点から、１０〜２５
％、特には１５〜２０％であることが望ましい。The total width of the band-shaped external electrodes 4 is
With respect to the outer peripheral length of a, from the viewpoint of satisfying low resistance and not inhibiting the vibration of the actuator,
%, Particularly preferably 15 to 20%.
【００３４】また、本発明の積層型圧電アクチュエータ
では、図１（ｃ）に示すように、柱状積層体１ａの側面
の点対称となる位置に、一対の帯状外部電極４が接合さ
れている。言い換えれば、一対の帯状外部電極４と柱状
積層体１ａとの接合部は、柱状積層体１ａの積層方向に
垂直な断面において、略点対称点Ｙが存在するように柱
状積層体１ａの断面形状を加工し、この部分に帯状外部
電極４を接合させることが好ましい。Further, in the multilayer piezoelectric actuator of the present invention, as shown in FIG. 1 (c), a pair of band-shaped external electrodes 4 are joined at point-symmetric positions on the side surfaces of the columnar laminated body 1a. In other words, the joint between the pair of band-shaped external electrodes 4 and the columnar laminated body 1a has a cross-sectional shape of the columnar laminated body 1a such that a substantially point-symmetric point Y exists in a cross section perpendicular to the laminating direction of the columnar laminated body 1a. And it is preferable to bond the band-shaped external electrode 4 to this portion.
【００３５】これは、柱状積層体１ａ断面において略点
対称点Ｙが存在することにより、アクチュエータを高速
で駆動させた場合に生じるアクチュエータの振動モード
を帯状外部電極４が阻害する割合が最も少なくなり、耐
久性に優れたアクチュエータを提供することができる。This is because the existence of the substantially point-symmetric point Y in the cross section of the columnar laminated body 1a minimizes the rate at which the belt-shaped external electrode 4 inhibits the vibration mode of the actuator that occurs when the actuator is driven at high speed. Thus, an actuator having excellent durability can be provided.
【００３６】なお、柱状積層体１ａの積層方向に垂直な
断面の形状は、円形、楕円形、四角形、多角形などから
なり、例えば、図２（ａ）（ｂ）に示すような８角形形
状の場合、図２（ｅ）（ｆ）の場合においても、略点対
称点Ｙが存在するように帯状外部電極４を形成すればよ
い。The shape of the cross section of the columnar laminated body 1a perpendicular to the laminating direction is a circle, an ellipse, a quadrangle, a polygon, etc., for example, an octagonal shape as shown in FIGS. 2 (a) and 2 (b). In the case of (2), even in the case of FIGS. 2E and 2F, the band-shaped external electrode 4 may be formed so that the substantially point-symmetric point Y exists.
【００３７】本発明の帯状外部電極４は、２５０℃以上
の５％重量減少温度を有する樹脂と導電剤とを含有する
導電性接着剤で形成されている。この帯状外部電極４に
はリード線６が接続固定され、このリード線６は帯状外
部電極４を外部の電圧供給部に接続する作用をなす。帯
状外部電極４の厚みは、各内部電極２に流れる電流を十
分に供給し、また、帯状外部電極４にクラックが発生す
るのを防止するという点から１０〜５００μｍが望まし
い。The belt-shaped external electrode 4 of the present invention is formed of a conductive adhesive containing a resin having a 5% weight loss temperature of 250 ° C. or more and a conductive agent. A lead wire 6 is connected and fixed to the strip-shaped external electrode 4, and the lead wire 6 functions to connect the strip-shaped external electrode 4 to an external voltage supply unit. The thickness of the band-shaped external electrode 4 is desirably 10 to 500 μm from the viewpoint of sufficiently supplying a current flowing through each of the internal electrodes 2 and preventing the band-shaped external electrode 4 from being cracked.
【００３８】導電剤としては、金属、導電性セラミック
ス、金属酸化物等が用いられ、これら導電剤のマトリッ
クスとして機能する樹脂が、２５０℃以上の５％重量減
少温度を有する樹脂とされている。これらの帯状外部電
極４は、導電性接着剤を柱状積層体１ａの側面に印刷等
の方法により被着させることによって形成される。As the conductive agent, metals, conductive ceramics, metal oxides and the like are used, and the resin functioning as a matrix of these conductive agents is a resin having a temperature of 250 ° C. or more and a 5% weight loss temperature. These band-shaped external electrodes 4 are formed by applying a conductive adhesive to the side surface of the columnar laminate 1a by a method such as printing.
【００３９】さらに、帯状外部電極４を構成するマトリ
ックス樹脂は、２５０℃以上の５％重量減少温度（一般
に樹脂の耐熱性は５％もしくは３％重量減少温度で評価
される）を有する樹脂であることが好ましい。Further, the matrix resin constituting the belt-shaped external electrode 4 is a resin having a 5% weight loss temperature of 250 ° C. or more (generally, the heat resistance of the resin is evaluated at 5% or 3% weight loss temperature). Is preferred.
【００４０】これは、帯状外部電極４を形成する導電性
接着剤のマトリックス樹脂を、５％重量減少温度が２５
０℃以上の樹脂とすることにより、自動車用燃料噴射弁
等の高温での使用に際して強い接着力を維持することが
可能となり、高温での使用環境下、高い印加電界で連続
駆動させる場合においても、柱状積層体１ａとの接着強
度を維持することができ、帯状外部電極４と内部電極２
が断線することを防ぐことができ、帯状外部電極４と内
部電極２の間でスパークすることを防止できる。This is because the matrix resin of the conductive adhesive for forming the band-shaped external electrode 4 is made to have a 5% weight loss temperature of 25.
By using a resin of 0 ° C. or higher, it becomes possible to maintain a strong adhesive force when used at high temperatures such as fuel injection valves for automobiles, and even when driven continuously at a high applied electric field under a high temperature use environment. , The adhesive strength with the columnar laminate 1a can be maintained, and the band-shaped external electrode 4 and the internal electrode 2 can be maintained.
Can be prevented from being disconnected, and sparking between the strip-shaped external electrode 4 and the internal electrode 2 can be prevented.
【００４１】ここで、樹脂の５％重量減少温度の測定方
法について説明する。まず、使用前の形態がワニス状の
樹脂である場合は、予め溶剤分の蒸発と樹脂の硬化を完
了させておく。そして、５％重量減少温度の測定には一
般的には熱重量分析法（ＴＧ）が用いられ、これは大気
中で一定の昇温速度（１〜１０℃／分）で試料となる樹
脂を昇温させ、そのときの重量を逐次測定しておく。そ
して、初期の重量に対して５％の重量が減少した時点の
温度がその樹脂の５％重量減少温度である。Here, a method for measuring the 5% weight loss temperature of the resin will be described. First, when the form before use is a varnish-like resin, the evaporation of the solvent and the curing of the resin are completed in advance. In general, thermogravimetric analysis (TG) is used to measure the 5% weight loss temperature, in which a resin serving as a sample is heated in the air at a constant heating rate (1 to 10 ° C./min). The temperature is raised, and the weight at that time is sequentially measured. The temperature at the time when the weight is reduced by 5% with respect to the initial weight is the 5% weight reduction temperature of the resin.
【００４２】５％重量減少温度が２５０℃以上の樹脂と
しては、ポリイミド、ポリアミドイミド、フッ素樹脂、
ポリエーテルエーテルケトン、ポリアリレート、ポリス
ルフォン等から、５％重量減少温度が２５０℃以上の樹
脂を選択して用いる必要がある。Examples of the resin whose 5% weight loss temperature is 250 ° C. or more include polyimide, polyamideimide, fluororesin,
It is necessary to select and use a resin having a 5% weight loss temperature of 250 ° C. or more from polyetheretherketone, polyarylate, polysulfone, or the like.
【００４３】また、本発明の帯状外部電極４を構成する
導電性接着剤は、弾性率２０ＧＰａ以下、伸度１０％以
上であることが好ましい。これは、帯状外部電極４を形
成する導電性接着剤の弾性率を２０ＧＰａ以下、伸度を
１０％以上とすることにより、該導電性接着剤と熱膨張
の異なる圧電体１及び内部電極２からなる柱状積層体１
ａと接合する際において発生する応力や、アクチュエー
タを駆動させる際に生じる応力を吸収することができる
ためである。The conductive adhesive constituting the strip-shaped external electrode 4 of the present invention preferably has an elastic modulus of 20 GPa or less and an elongation of 10% or more. This is because by setting the elastic modulus of the conductive adhesive forming the strip-shaped external electrode 4 to 20 GPa or less and the elongation to 10% or more, the piezoelectric material 1 and the internal electrode 2 having different thermal expansion from the conductive adhesive can be used. Columnar laminate 1
This is because it is possible to absorb the stress generated when joining with a and the stress generated when driving the actuator.
【００４４】導電性接着剤の弾性率を２０ＧＰａ以下、
伸度を１０％以上とするためには、該導電性接着剤を構
成するマトリックス樹脂の弾性率を低く、伸度を大きく
することが望ましい。The elastic modulus of the conductive adhesive is 20 GPa or less,
In order to make the elongation 10% or more, it is desirable that the elastic modulus of the matrix resin constituting the conductive adhesive is low and the elongation is high.
【００４５】さらに、前記帯状外部電極４を構成する導
電性接着剤中の導電剤の含有比率は、１５〜８０体積％
にすることが望ましい。これは、導電剤粒子間の接触を
良好とすることができ、導電性接着剤の比抵抗を小さく
できるとともに、柱状積層体１ａとの接着強度を維持で
きるからである。Further, the content ratio of the conductive agent in the conductive adhesive constituting the strip-shaped external electrode 4 is 15 to 80% by volume.
Is desirable. This is because the contact between the conductive agent particles can be improved, the specific resistance of the conductive adhesive can be reduced, and the adhesive strength with the columnar laminate 1a can be maintained.
【００４６】一方、導電剤の含有量が１５体積％より少
ないと導電剤粒子間の接触が困難となって、該導電性接
着剤の比抵抗が大きくなり、電圧を印可した際に局所発
熱が発生する虞があり、内部電極２と帯状外部電極４と
の接合部でスパークしてしまう恐れがあるからであり、
導電剤の含有量を８０体積％より多くすると、接着を担
っているマトリックス樹脂の含有量が相対的に少なくな
り、柱状積層体１ａとの接着強度が低下するからであ
る。On the other hand, if the content of the conductive agent is less than 15% by volume, contact between the conductive agent particles becomes difficult, the specific resistance of the conductive adhesive increases, and local heat generation occurs when a voltage is applied. This is because there is a danger that sparks will occur at the joint between the internal electrode 2 and the strip-shaped external electrode 4,
This is because, when the content of the conductive agent is more than 80% by volume, the content of the matrix resin which is responsible for the bonding becomes relatively small, and the bonding strength with the columnar laminate 1a decreases.
【００４７】帯状外部電極４に含有する導電剤として
は、Ａｇ、Ｐｄ、Ｎｉ等の周期律表第６族〜第１１族の
金属やＷＣ、ＴｉＮ等の金属炭化物や窒化物、ＲｕＯ2
等の金属酸化物、若しくはこれらの合金や混合物を用
い、これらは耐酸化性、導電性が良好であるため導電剤
として好ましい。導電剤としては、安価で導電性が良好
であるという点から金属、特にＡｇからなることが望ま
しい。Examples of the conductive agent contained in the band-shaped external electrode 4 include metals of Group 6 to Group 11 of the periodic table such as Ag, Pd, and Ni, metal carbides and nitrides such as WC and TiN, and RuO 2.
And the like, or an alloy or a mixture thereof, which is preferable as a conductive agent because of its excellent oxidation resistance and conductivity. The conductive agent is preferably made of a metal, particularly Ag, from the viewpoint that it is inexpensive and has good conductivity.
【００４８】また、導電剤粉末の形状は針状やフレーク
状などの非球形の粉末であることが望ましく、これは導
電剤粒子の形状を針状やフレーク状などの非球形とする
ことにより、球形の場合よりも導電剤粒子間の絡み合い
が大きくなり、該導電性接着剤の剪断強度を大きく向上
させることができるからである。非球形粉末と球形粉末
を併用しても構わない。The shape of the conductive agent powder is desirably a non-spherical powder such as a needle or flake. This is because the shape of the conductive agent particles is made non-spherical such as a needle or flake. This is because the entanglement between the conductive agent particles is larger than in the case of the spherical shape, and the shear strength of the conductive adhesive can be greatly improved. Non-spherical powder and spherical powder may be used in combination.
【００４９】また、帯状外部電極４を構成するマトリッ
クス樹脂は、ポリイミドやポリアミドイミドなどのイミ
ド結合を有する有機樹脂であることが望ましい。これら
ポリイミドやポリアミドイミド等のようにイミド結合を
有する分子構造の樹脂は、有機樹脂の中でも特に耐熱性
に優れており、耐熱性に優れた有機樹脂を含有すること
によって、高温で使用した際にも強い接合強度をたもつ
ことができる。The matrix resin constituting the belt-shaped external electrode 4 is desirably an organic resin having an imide bond such as polyimide or polyamide imide. Resins having a molecular structure having an imide bond such as these polyimides and polyamide imides are particularly excellent in heat resistance among organic resins, by containing an organic resin having excellent heat resistance, when used at high temperatures Can also have a strong bonding strength.
【００５０】さらに、帯状外部電極４に含有されるマト
リックス樹脂を熱可塑性で、ガラス転移温度が１８０℃
以上であるもので形成しておくことが好ましい。このよ
うに、マトリックス樹脂を熱可塑性とすると、アクチュ
エータの使用環境がヒートサイクル的な条件であった場
合に、帯状外部電極４と柱状積層体１ａとの熱膨張差に
よって生じる応力を十分に吸収することができ、帯状外
部電極４が柱状積層体１ａから外れるのを防ぐことがで
きる。Further, the matrix resin contained in the belt-like external electrode 4 is made of thermoplastic resin and has a glass transition temperature of 180 ° C.
It is preferable to form the above. As described above, when the matrix resin is made thermoplastic, the stress generated by the difference in thermal expansion between the band-shaped external electrode 4 and the columnar laminate 1a is sufficiently absorbed when the operating environment of the actuator is a heat cycle condition. This can prevent the strip-shaped external electrode 4 from coming off the columnar laminate 1a.
【００５１】また、一般にガラス転移温度以上の温度で
樹脂を使用すると、その強度は著しく低下するため、帯
状外部電極４を構成する樹脂のガラス転移温度を１８０
℃以上としておくと、温度条件が厳しい自動車用燃料噴
射弁等に用いる場合も十分耐えうる。In general, when a resin is used at a temperature higher than the glass transition temperature, its strength is remarkably reduced.
When the temperature is set to not less than ° C., it can sufficiently withstand the case where it is used for a fuel injection valve for an automobile having severe temperature conditions.
【００５２】そして、リード線６を介して一対の帯状外
部電極４に０．１〜３ｋＶ／ｍｍの直流電圧を印加し、
柱状積層体１ａを分極処理することによって、製品とし
ての積層型圧電アクチュエータが完成し、リード線６を
外部の電圧供給部に接続し、リード線６及び帯状外部電
極４を介して内部電極２に電圧を印加させれば、各圧電
体１は逆圧電効果によって大きく変位し、これによって
例えばエンジンに燃料を噴射供給する自動車用燃料噴射
弁として機能する。Then, a DC voltage of 0.1 to 3 kV / mm is applied to the pair of strip-shaped external electrodes 4 via the lead wires 6,
By polarizing the columnar laminated body 1a, a laminated piezoelectric actuator as a product is completed. The lead wire 6 is connected to an external voltage supply unit, and is connected to the internal electrode 2 via the lead wire 6 and the band-shaped external electrode 4. When a voltage is applied, each piezoelectric body 1 is largely displaced by the inverse piezoelectric effect, thereby functioning as, for example, an automobile fuel injection valve that injects fuel into an engine.
【００５３】以上のように構成された積層型圧電アクチ
ュエータでは、一対の帯状外部電極４の合計幅が、柱状
積層体１ａの外周長さに対して５〜３０％とされている
ため、帯状外部電極４と内部電極２の接合部の抵抗を十
分に低くすることができ、局所発熱やスパークが起こる
といった問題を防ぐとともに、帯状外部電極４が振動を
阻害することがなく、高信頼性のアクチュエータを提供
することができる。In the multilayer piezoelectric actuator configured as described above, the total width of the pair of band-shaped external electrodes 4 is 5 to 30% with respect to the outer peripheral length of the columnar laminated body 1a. The resistance at the junction between the electrode 4 and the internal electrode 2 can be sufficiently reduced to prevent problems such as local heat generation and spark generation, and the strip-shaped external electrode 4 does not hinder the vibration, thereby providing a highly reliable actuator. Can be provided.
【００５４】なお、本発明は上述の実施例に限定される
ものではなく、本発明の要旨を逸脱しない範囲であれば
種々の変更は可能であり、例えば上述の実施例において
帯状外部電極４を含めた柱状積層体１ａをシリコーンゴ
ム等の絶縁被覆剤で被覆しておくと、外部からの水分の
侵入を阻止することができる。また、銀−パラジウムか
らなる内部電極２にマイグレーションが発生するのを抑
制することができ、これによって柱状積層体１ａの側面
に露出している内部電極２の端部の電気的絶縁を確保す
ることができる。It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. When the columnar laminated body 1a is covered with an insulating coating material such as silicone rubber, intrusion of moisture from the outside can be prevented. In addition, it is possible to suppress the occurrence of migration in the internal electrode 2 made of silver-palladium, thereby ensuring electrical insulation of the end of the internal electrode 2 exposed on the side surface of the columnar laminate 1a. Can be.
【００５５】さらに、図３に示すように、帯状外部電極
４を薄板状の導電部材４ｂと導電性接着剤からなる下地
部材４ａとで形成してもよい。帯状外部電極４を導電部
材４ｂと耐熱性、柔軟性に富んだ下地部材４ａとで形成
することにより、圧電体１が逆圧電効果により大きく変
位したとしても下地部材４ａがそれにあわせて変化する
とともに、帯状外部電極４を柱状積層体１ａにきわめて
強固に接合しておくことができる。Further, as shown in FIG. 3, the strip-shaped external electrode 4 may be formed of a thin plate-shaped conductive member 4b and a base member 4a made of a conductive adhesive. By forming the band-shaped external electrode 4 with the conductive member 4b and the base member 4a having high heat resistance and flexibility, even if the piezoelectric body 1 is greatly displaced by the inverse piezoelectric effect, the base member 4a changes in accordance with the displacement. In addition, the band-shaped external electrode 4 can be very firmly joined to the columnar laminate 1a.
【００５６】また、同時に外部電極層４は一部が薄板状
の導電部材４ｂで形成されていることから、帯状外部電
極４の導体抵抗を小さくすることができ、これによって
帯状外部電極４を介して内部電極２にロスを少なくして
所定の電圧を供給することができ、圧電体１に逆圧電効
果により大きな変位を起こさせることが可能となる。At the same time, since the external electrode layer 4 is partially formed of the thin plate-shaped conductive member 4b, the conductor resistance of the strip-shaped external electrode 4 can be reduced. Thus, a predetermined voltage can be supplied to the internal electrode 2 with a reduced loss, and a large displacement can be caused in the piezoelectric body 1 by the inverse piezoelectric effect.
【００５７】なお、前記導電部材４ｂの材質としては、
Ａｇ、Ｎｉ、Ｃｕ、Ａｌ、Ｗ、Ｍｏ、ステンレス、Ｆｅ
−Ｎｉ−Ｃｏ合金等の導電性を備え、且つ薄板化が可能
な金属材料からなり、このうち、耐酸化性が良好で、導
電性が良いという点から、Ａｇ、Ｎｉ、ステンレスが望
ましく、導電部材４ｂの厚みは、低抵抗であり、且つ、
剛性が低いという点から２０〜２００μｍ程度であるこ
とが望ましい。The material of the conductive member 4b is as follows.
Ag, Ni, Cu, Al, W, Mo, stainless steel, Fe
-Made of a metal material having electrical conductivity such as a Ni-Co alloy and capable of being made thinner, and among them, Ag, Ni, and stainless steel are desirable in terms of good oxidation resistance and good electrical conductivity, and The thickness of the member 4b is low, and
From the viewpoint of low rigidity, the thickness is preferably about 20 to 200 μm.
【００５８】さらに、導電部材４ｂはメッシュ状である
ことが好ましい。これは、導電部材４ｂをメッシュ状と
することにより、該導電部材４ｂがアクチュエータの伸
縮に柔軟に追従することが可能となり、高い印加電界で
高速で駆動させた場合においても、帯状外部電極４がア
クチュエータの振動を阻害することなく、また、帯状外
部電極４と内部電極２とが断線することなく高耐久性を
備えた積層型圧電アクチュエータを提供することができ
る。Further, the conductive member 4b is preferably in a mesh shape. This is because the conductive member 4b has a mesh shape, so that the conductive member 4b can flexibly follow the expansion and contraction of the actuator. Even when driven at a high speed with a high applied electric field, the band-shaped external electrode 4 It is possible to provide a laminated piezoelectric actuator having high durability without inhibiting vibration of the actuator and without disconnection between the strip-shaped external electrode 4 and the internal electrode 2.
【００５９】なお、メッシュ状の導電部材４ｂは、直径
１０〜１００μｍの金属の線材を編み込んだタイプで
も、金属の薄板に化学エッチング等の処理にて一定の大
きさ、間隔で穴をあけたタイプでも構わない。このよう
なメッシュ状の導電部材４ｂは導電性接着剤中に埋設さ
れる場合がある。The mesh-shaped conductive member 4b may be a type in which a metal wire having a diameter of 10 to 100 μm is woven, or a type in which holes are formed in a metal thin plate at a predetermined size and interval by a process such as chemical etching. But it doesn't matter. Such a mesh-shaped conductive member 4b may be buried in a conductive adhesive.
【００６０】[0060]
【実施例】（実施例１）まず、柱状積層体の積層方向に
垂直な断面が、１辺長さ７ｍｍの正方形（Ｌ1＝Ｌ2）
で、対向する２側面に柱状積層体断面に略点対称点が存
在するように、帯状外部電極の幅（接合部長さ）Ｘが２
ｍｍ（正極、負極併せて４ｍｍ）の外部電極を形成し、
図１に示す積層型圧電アクチュエータを作製した。(Example 1) First, a cross section perpendicular to the laminating direction of a columnar laminated body was a square (L 1 = L 2 ) with a side length of 7 mm.
Then, the width (joint length) X of the band-shaped external electrode is set to 2 so that a point symmetry point exists in the cross section of the columnar laminate on the two opposing side surfaces.
mm (4 mm for both positive and negative electrodes)
The laminated piezoelectric actuator shown in FIG. 1 was manufactured.
【００６１】なお、外部電極は、５％重量減少温度３０
０℃のポリイミドをマトリックス樹脂に、導電剤として
４０体積％の銀粉末を用いた弾性率１０ＧＰａ、伸度３
０％の導電性接着剤にて形成した。Note that the external electrode has a 5% weight loss temperature of 30.
Elasticity 10 GPa, elongation 3 using 40 vol% silver powder as conductive agent with polyimide at 0 ° C as matrix resin
Formed with 0% conductive adhesive.
【００６２】また、圧電体は厚み１００μｍのＰＺＴで
形成し、内部電極は厚み３μｍの銀−パラジウム合金に
よって形成し、圧電体及び内部電極の各々の積層数は３
００とした。また、柱状積層体側面の外部電極形成面に
おいて、内部電極の露出する端部には一層おきに左右交
互に溝を形成し、該溝には絶縁体としてシリコーンゴム
を充填した。The piezoelectric body is formed of PZT having a thickness of 100 μm, the internal electrode is formed of a silver-palladium alloy having a thickness of 3 μm, and the number of layers of each of the piezoelectric body and the internal electrode is three.
00. Further, on the external electrode forming surface on the side surface of the columnar laminate, grooves were formed alternately on the left and right sides at the exposed ends of the internal electrodes, and the grooves were filled with silicone rubber as an insulator.
【００６３】その後、正極及び負極の外部電極にリード
線を介して３ｋＶ／ｍｍの直流電界を１５分間印加して
分極処理を行い、積層型圧電アクチュエータを得た。Thereafter, a direct current electric field of 3 kV / mm was applied to the external electrodes of the positive electrode and the negative electrode via the lead wires for 15 minutes to perform a polarization treatment, thereby obtaining a laminated piezoelectric actuator.
【００６４】得られた積層型圧電アクチュエータに２０
０Ｖの直流電圧を印加した結果、積層方向に５０μｍの
変位量が得られた。さらに、このアクチュエータに室温
で０〜＋２００Ｖの交流電圧を６０Ｈｚの周波数にて印
加し駆動試験を行った結果、５×１０7サイクル駆動す
るまで５０μｍの変位量を維持した。さらに１×１０9
サイクルまで駆動したところ５０μｍの変位量が得ら
れ、外部電極の異常は見られなかった。20 was added to the obtained laminated piezoelectric actuator.
As a result of applying a DC voltage of 0 V, a displacement of 50 μm was obtained in the stacking direction. Further, an AC voltage of 0 to +200 V was applied to the actuator at room temperature at a frequency of 60 Hz, and a drive test was performed. As a result, a displacement of 50 μm was maintained until the actuator was driven for 5 × 10 7 cycles. 1 × 10 9
When driven up to the cycle, a displacement amount of 50 μm was obtained, and no abnormality of the external electrode was observed.
【００６５】さらに、本発明者は、この積層型圧電アク
チュエータを２００℃の環境雰囲気中で０〜＋２００Ｖ
の交流電圧を６０Ｈｚの周波数で印加した場合でも、５
×１０8サイクルまで外部電極が断線することなく初期
と同等の変位を維持することができた。Further, the inventor of the present invention has set the laminated piezoelectric actuator in an environmental atmosphere at 200 ° C. from 0 to +200 V.
Even when an AC voltage of 60 Hz is applied at a frequency of 60 Hz,
Up to × 10 8 cycles, the displacement equivalent to that of the initial stage could be maintained without disconnection of the external electrode.
【００６６】従って、柱状積層体の積層方向に垂直な断
面において、帯状外部電極の幅が、柱状積層体断面の外
周長さの１４．３％で、柱状積層体断面に略点対称点が
存在する本発明の積層型圧電アクチュエータは、その駆
動時に発生するアクチュエータの振動を外部電極が阻害
することなく、また、該アクチュエータの振動モードを
阻害しない断面形状であるために、アクチュエータを高
速で駆動させた場合においても外部電極が断線したり、
柱状積層体に不具合が生じたりするのを防ぐことができ
る。 （実施例２）次に、帯状外部電極の幅を変化させた以外
は、実施例１と同様の構成の積層型圧電アクチュエータ
を作製した。なお、断面の形状は１辺長さ７ｍｍの正方
形である。得られた積層型圧電アクチュエータに室温で
２００Ｖの交流電圧を６０Ｈｚの周波数にて印加し、駆
動試験を行った。変位量は５０μｍであった。尚、サン
プルＮｏ．３は実施例１を示す。結果を表１に示す。Accordingly, in the cross section perpendicular to the laminating direction of the columnar laminate, the width of the strip-shaped external electrode is 14.3% of the outer peripheral length of the columnar laminate, and a point symmetry point exists in the cross section of the columnar laminate. The multilayer piezoelectric actuator according to the present invention has a cross-sectional shape that does not hinder the vibration of the actuator generated at the time of its driving by the external electrode and does not hinder the vibration mode of the actuator. The external electrode is disconnected even if
It is possible to prevent problems from occurring in the columnar laminate. (Example 2) Next, a laminated piezoelectric actuator having the same configuration as that of Example 1 except that the width of the band-shaped external electrode was changed was manufactured. The shape of the cross section is a square with a side length of 7 mm. A drive test was performed by applying an AC voltage of 200 V at room temperature at a frequency of 60 Hz to the obtained laminated piezoelectric actuator. The displacement was 50 μm. The sample No. 3 shows the first embodiment. Table 1 shows the results.
【００６７】[0067]
【表１】 [Table 1]
【００６８】サンプルＮｏ．１は、柱状積層体の積層方
向に垂直な断面における帯状外部電極の幅が、柱状積層
体断面の外周長さの５％より小さいために、外部電極か
ら内部電極に電圧を供給する際に流れる電流に対して外
部電極と内部電極の接合面積が小さいために、接合部の
抵抗が高くなり、該接合部が局所発熱を起こし、外部電
極がスパークしてしまった。Sample No. 1 flows when a voltage is supplied from the external electrode to the internal electrode because the width of the band-shaped external electrode in a cross section perpendicular to the laminating direction of the columnar laminate is smaller than 5% of the outer peripheral length of the cross section of the columnar laminate. Since the junction area between the external electrode and the internal electrode was small with respect to the current, the resistance of the junction increased, and the junction generated local heat, sparking the external electrode.
【００６９】一方、サンプルＮｏ．６は、外部電極の幅
が、柱状積層体断面の外周長さの３０％より大きいため
に、アクチュエータを高速で駆動させた場合に、積層方
向に垂直な方向の幅の広い外部電極がアクチュエータの
伸縮運動によって生じる振動モードを阻害し、アクチュ
エータが破損したことが確認された。On the other hand, the sample No. No. 6, since the width of the external electrode is larger than 30% of the outer peripheral length of the cross section of the columnar laminate, when the actuator is driven at a high speed, the external electrode having a wide width in the direction perpendicular to the lamination direction It was confirmed that the vibration mode caused by the expansion and contraction motion was disturbed and the actuator was damaged.
【００７０】ここで、サンプルＮｏ．２、３、４、５
は、外部電極の幅が、柱状積層体断面の外周長さの５〜
３０％であるために、外部電極と内部電極の接合部の抵
抗を十分低くすることができ、局所発熱やスパークとい
った問題が生じておらず、また、外部電極の積層方向に
垂直な方向の幅が狭いために外部電極がアクチュエータ
の振動を阻害することなく、アクチュエータが破損する
といった問題も生じていないことが確認できた。 （実施例３）次に、柱状積層体の積層方向に垂直な断面
の形状と、外部電極の形成位置を数種変化させた以外
は、実施例１と同様の構成の積層型圧電アクチュエータ
を作製した。なお、前記柱状積層体断面の形状は図１
（ｃ）、図２（ａ）〜（ｆ）に示してある。得られた積
層型圧電アクチュエータに室温で２００Ｖの交流電圧を
６０Ｈｚの周波数にて印加し、駆動試験を行った。変位
量は５０μｍであった。結果を表２に示す。Here, the sample No. 2, 3, 4, 5
Is that the width of the external electrode is 5 to 5 times the outer peripheral length of the cross section of the columnar laminate.
Since it is 30%, the resistance at the junction between the external electrode and the internal electrode can be sufficiently reduced, and no problems such as local heat generation and sparking occur. In addition, the width of the external electrode in the direction perpendicular to the laminating direction. It was confirmed that the external electrodes did not hinder the vibration of the actuator due to the small width, and there was no problem that the actuator was damaged. (Example 3) Next, a laminated piezoelectric actuator having the same configuration as in Example 1 except that the shape of the cross section perpendicular to the laminating direction of the columnar laminated body and the formation positions of the external electrodes were changed several types. did. The cross-sectional shape of the columnar laminate is shown in FIG.
2 (c) and FIGS. 2 (a) to 2 (f). A drive test was performed by applying an AC voltage of 200 V at room temperature at a frequency of 60 Hz to the obtained laminated piezoelectric actuator. The displacement was 50 μm. Table 2 shows the results.
【００７１】[0071]
【表２】 [Table 2]
【００７２】サンプルＮｏ．７、８、９、１２、１３
は、略点対称点が存在するために、アクチュエータを高
速で駆動させた場合に生じるアクチュエータの振動モー
ドを外部電極が阻害する程度が低いために、アクチュエ
ータが破損するといった問題は生じていない。Sample No. 7, 8, 9, 12, 13
However, there is no problem that the actuator is damaged because the external electrode hinders the vibration mode of the actuator caused when the actuator is driven at a high speed because of the existence of the substantially point-symmetric point.
【００７３】一方、サンプルＮｏ．１０、１１は柱状積
層体断面において、略点対称点が存在しないために、ア
クチュエータを高速で駆動させた場合に、アクチュエー
タに生じる振動が外部電極によって阻害されるために、
アクチュエータが破損するといった問題が生じてしまっ
た。On the other hand, the sample No. 10 and 11 do not have a point symmetry point in the cross section of the columnar laminate, and when the actuator is driven at a high speed, vibrations generated in the actuator are obstructed by the external electrodes.
A problem such as breakage of the actuator has occurred.
【００７４】即ち、サンプルＮｏ．７、８、９、１２、
１３のように、柱状積層体断面に略点対称点が存在する
ように外部電極を形成することにより、アクチュエータ
を高速で駆動させた場合においてもアクチュエータ本体
が破損するといった問題が生じないことが分かる。 （実施例４）次に、５％重量減少温度が表３に示す値の
樹脂と導電剤として４０体積％の銀粉末を用いた導電性
接着剤にて外部電極を形成した以外は、実施例１と同様
の構成の積層型圧電アクチュエータを作製した。得られ
た積層型圧電アクチュエータについて、２００℃の雰囲
気中で２００Ｖ交流電圧を６０Ｈｚの周波数にて印加
し、駆動試験を行った。変位量は５０μｍであった。結
果を表３に示す。That is, the sample No. 7, 8, 9, 12,
As shown in FIG. 13, by forming the external electrode so that a point symmetry point exists in the cross-section of the columnar laminate, it is understood that the problem that the actuator main body is broken does not occur even when the actuator is driven at a high speed. . (Example 4) Next, the external electrodes were formed using a resin having a 5% weight loss temperature shown in Table 3 and a conductive adhesive using 40% by volume of silver powder as a conductive agent. A laminated piezoelectric actuator having the same configuration as that of No. 1 was produced. A drive test was performed on the obtained laminated piezoelectric actuator by applying a 200 V AC voltage at a frequency of 60 Hz in an atmosphere at 200 ° C. The displacement was 50 μm. Table 3 shows the results.
【００７５】[0075]
【表３】 [Table 3]
【００７６】サンプルＮｏ．１４、１５は外部電極を形
成する樹脂の５％重量減少温度が２５０℃より低いため
に、高温での雰囲気中で接着強度を維持することができ
ずに、外部電極が柱状積層体から外れ、スパークが生じ
てしまっている。Sample No. In Nos. 14 and 15, since the resin forming the external electrodes has a 5% weight loss temperature lower than 250 ° C., the adhesive strength cannot be maintained in an atmosphere at a high temperature, and the external electrodes come off from the columnar laminate. A spark has occurred.
【００７７】一方、サンプルＮｏ．１６、１７において
は、前記樹脂の５％重量減少温度が２５０℃以上と高い
ため、高温で使用した場合においても外部電極の接着強
度を維持することが可能で、外部電極が柱状積層体から
剥離したり、外部電極にクラックを生じたりすることが
なく、高耐久性を備えていることが分かる。 （実施例５）次に、導電材として４０体積％の銀粉末を
用い、弾性率及び伸度を、表４に示す値に変化させた導
電性接着剤にて外部電極を形成した以外は、実施例１と
同様の構成の積層型圧電アクチュエータを作製した。得
られた積層型圧電アクチュエータについて、室温で２５
０Ｖの交流電圧を６０Ｈｚの周波数にて印加し、駆動試
験を行った。変位量は６０μｍであった。結果を表４に
示す。On the other hand, the sample No. In Nos. 16 and 17, since the 5% weight loss temperature of the resin is as high as 250 ° C. or higher, the adhesive strength of the external electrode can be maintained even when used at a high temperature, and the external electrode is separated from the columnar laminate. It can be seen that the electrode has high durability without causing cracking or cracking of the external electrode. (Example 5) Next, except that 40% by volume of silver powder was used as a conductive material, and an external electrode was formed with a conductive adhesive whose elastic modulus and elongation were changed to the values shown in Table 4, A laminated piezoelectric actuator having the same configuration as that of the first embodiment was manufactured. Regarding the obtained laminated piezoelectric actuator, 25
A drive test was performed by applying an AC voltage of 0 V at a frequency of 60 Hz. The displacement was 60 μm. Table 4 shows the results.
【００７８】[0078]
【表４】 [Table 4]
【００７９】サンプルＮｏ．１８、１９及び２０は、外
部電極を形成する導電性接着剤の弾性率が２０ＧＰａ以
上、伸度が１０％以下であるため、外部電極がアクチュ
エータ本体の伸縮に追従できずに、外部電極にクラック
が発生しているのが確認された。Sample No. 18, 19 and 20, the conductive adhesive forming the external electrode has an elastic modulus of 20 GPa or more and an elongation of 10% or less, so that the external electrode cannot follow the expansion and contraction of the actuator body, and the external electrode cracks. Was confirmed to have occurred.
【００８０】一方、サンプルＮｏ．２１、２２及び２３
は外部電極を形成する導電性接着剤の弾性率が２０ＧＰ
ａ以下で伸度が１０％以上で柔軟性に富むため、アクチ
ュエータ本体の伸縮に対して前記外部電極が追従できる
ため、外部電極と柱状積層体の界面に大きな応力が生じ
ることなく、外部電極の破損など異常は見られなかっ
た。 （実施例６）次に、外部電極の形成方法を表５に示すよ
うにして作製した以外は、実施例１と同様の構成の積層
型圧電アクチュエータを作製した。外部電極は銀粉末を
分散させたガラスペーストを用いて形成した場合（サン
プルＮｏ．２４）と、５％重量減少温度３００℃のポリ
イミドをマトリックス樹脂に、導電剤として４０体積％
の銀粉末を用いた弾性率１０ＧＰａ、伸度３０％の導電
性接着剤にて形成した場合（サンプルＮｏ．２５）、さ
らに、前記導電性接着剤と厚み５０μｍのステンレスの
薄板状の導電部材とから形成した場合（サンプルＮｏ．
２６）、さらに前記導電性接着剤と厚み５０μｍのステ
ンレスのメッシュ状の導電部材とから形成した場合（サ
ンプルＮｏ．２７）の４通りである。On the other hand, the sample No. 21, 22, and 23
Means that the elastic modulus of the conductive adhesive forming the external electrode is 20 GP
Since the elongation is 10% or more and the flexibility is high at a or less, the external electrode can follow the expansion and contraction of the actuator body. Therefore, a large stress does not occur at the interface between the external electrode and the columnar laminate, and the external electrode No abnormalities such as damage were observed. (Example 6) Next, a laminated piezoelectric actuator having the same configuration as in Example 1 except that the external electrode was formed as shown in Table 5 was manufactured. When the external electrode was formed using a glass paste in which silver powder was dispersed (Sample No. 24), polyimide having a 5% weight loss temperature of 300 ° C. was used as a matrix resin, and 40% by volume as a conductive agent.
When formed with a conductive adhesive having an elastic modulus of 10 GPa and an elongation of 30% using silver powder (sample No. 25), the conductive adhesive and a 50 μm-thick stainless steel-like conductive member were further added. (Sample No.
26) and four cases where the conductive adhesive and the stainless steel mesh conductive member having a thickness of 50 μm are formed (sample No. 27).
【００８１】得られた積層型圧電アクチュエータに室温
で２５０Ｖの交流電圧を１００Ｈｚの周波数にて印加
し、駆動試験を行った。変位量は６０μｍであった。結
果を表５に示すA driving test was performed by applying an AC voltage of 250 V at a frequency of 100 Hz to the obtained laminated piezoelectric actuator at room temperature. The displacement was 60 μm. The results are shown in Table 5.
【００８２】[0082]
【表５】 [Table 5]
【００８３】サンプルＮｏ．２４の場合、外部電極がヤ
ング率の高い銀分散のガラスペーストで形成されている
ために、アクチュエータ本体の伸縮に外部電極が追従で
きずに外部電極とアクチュエータ本体の間に引っ張り応
力が生じ、外部電極と内部電極との接続部においてクラ
ックが発生し、スパークが生じてしまった。Sample No. In the case of No. 24, since the external electrode is formed of a silver-dispersed glass paste having a high Young's modulus, the external electrode cannot follow the expansion and contraction of the actuator main body, and a tensile stress is generated between the external electrode and the actuator main body. Cracks occurred at the connection between the electrode and the internal electrode, resulting in sparking.
【００８４】一方、本発明の導電性接着剤にて外部電極
を形成したサンプルＮｏ．２５の場合は、外部電極がア
クチュエータ本体の伸縮に十分追従でき、高速で連続駆
動した場合においても変位量はほとんど減少しなかっ
た。On the other hand, in sample No. 1 in which external electrodes were formed using the conductive adhesive of the present invention. In the case of No. 25, the external electrode could sufficiently follow the expansion and contraction of the actuator body, and the displacement amount hardly decreased even when the actuator was continuously driven at a high speed.
【００８５】さらに、外部電極を薄板状の導電部材と本
発明の導電性接着剤とで形成したサンプルＮｏ．２６及
びメッシュ状の導電部材と前記導電性接着剤とで形成し
たサンプルＮｏ．２７の場合は、高い印加電圧で高速で
連続駆動させた場合にも、外部電極が断線することなく
高い信頼性を備えていることが分かった。特に、外部電
極をメッシュ状の導電部材と本発明の導電性接着剤にて
形成したサンプルＮｏ．２７の場合には、前記メッシュ
状導電部材がフレキシブルであるために前記導電性接着
剤と同様アクチュエータ本体に伸縮に十分追従すること
ができ、高速で長時間連続駆動した場合でもその変位量
が変化することがなかった。Further, Sample No. 1 in which the external electrode was formed of a thin plate-shaped conductive member and the conductive adhesive of the present invention. Sample No. 26 formed of a mesh-shaped conductive member and the conductive adhesive. In the case of No. 27, it was found that even when the device was continuously driven at a high speed with a high applied voltage, the external electrodes had high reliability without disconnection. In particular, the sample No. in which the external electrode was formed of a mesh-shaped conductive member and the conductive adhesive of the present invention. In the case of No. 27, since the mesh-shaped conductive member is flexible, it can follow the expansion and contraction of the actuator body sufficiently like the conductive adhesive, and the displacement amount changes even when driven continuously at high speed for a long time. I never did.
【００８６】[0086]
【発明の効果】本発明の積層型圧電アクチュエータによ
れば、一対の帯状外部電極の合計幅を、柱状積層体の外
周長さに対して５〜３０％としたので、外部電極と内部
電極の接合部の抵抗を十分に低くすることができ、局所
発熱やスパークが起こるといった問題を防ぐとともに、
外部電極がアクチュエータの振動を阻害することがな
く、高信頼性のアクチュエータを提供することができ
る。According to the laminated piezoelectric actuator of the present invention, the total width of the pair of band-shaped external electrodes is set to 5 to 30% of the outer peripheral length of the columnar laminated body. The resistance of the joint can be made sufficiently low, preventing problems such as local heat generation and sparks,
An external electrode does not hinder the vibration of the actuator, and a highly reliable actuator can be provided.
【図１】本発明の積層型圧電アクチュエータを示すもの
で、（ａ）は斜視図、（ｂ）は（ａ）のＡ−Ａ’線断面
図、（ｃ）は（ａ）のＢ−Ｂ’線断面図である。1A and 1B show a laminated piezoelectric actuator of the present invention, wherein FIG. 1A is a perspective view, FIG. 1B is a cross-sectional view taken along the line AA ′ of FIG. 1A, and FIG. FIG.
【図２】積層型圧電アクチュエータの積層方向に垂直な
断面図である。FIG. 2 is a cross-sectional view perpendicular to the stacking direction of the stacked piezoelectric actuator.
【図３】本発明の他の積層型圧電アクチュエータを示す
もので、（ａ）は斜視図、（ｂ）は（ａ）はＣ−Ｃ’線
断面図、（ｃ）は（ａ）のＤ−Ｄ’線断面図である。3A and 3B show another laminated piezoelectric actuator of the present invention, wherein FIG. 3A is a perspective view, FIG. 3B is a cross-sectional view taken along the line CC ′ of FIG. 3A, and FIG. It is a sectional view taken along line -D '.
【図４】従来の積層型圧電アクチュエータの断面図であ
る。FIG. 4 is a sectional view of a conventional laminated piezoelectric actuator.
１・・・圧電体 １ａ・・・柱状積層体 ２・・・内部電極 ４・・・帯状外部電極 ４ａ・・・下地部材（導電性接着剤） ４ｂ・・・導電部材 DESCRIPTION OF SYMBOLS 1 ... Piezoelectric body 1a ... Columnar laminated body 2 ... Internal electrode 4 ... Band-shaped external electrode 4a ... Base member (conductive adhesive) 4b ... Conductive member
Claims (6)
積層して形成された柱状積層体と、前記内部電極が一層
おきに交互に接続され、前記柱状積層体の側面に接合さ
れた一対の帯状外部電極とを具備してなる積層型圧電ア
クチュエータであって、前記一対の帯状外部電極の合計
幅を、前記柱状積層体の外周長さに対して５〜３０％と
したことを特徴とする積層型圧電アクチュエータ。1. A columnar laminated body formed by alternately laminating a plurality of piezoelectric bodies and a plurality of internal electrodes, and the internal electrodes are alternately connected every other layer and joined to a side surface of the columnar laminated body. And a total width of the pair of band-shaped external electrodes is set to 5 to 30% with respect to an outer peripheral length of the columnar stacked body. Characteristic multilayer piezoelectric actuator.
一対の帯状外部電極が接合されていることを特徴とする
請求項１記載の積層型圧電アクチュエータ。2. The method according to claim 2, wherein the side surfaces of the columnar laminate are point-symmetrical.
The multilayer piezoelectric actuator according to claim 1, wherein a pair of band-shaped external electrodes are joined.
減少温度を有する樹脂と導電剤とを含有する導電性接着
剤で形成されていることを特徴とする請求項１または２
記載の積層型圧電アクチュエータ。3. The belt-shaped external electrode is made of a conductive adhesive containing a resin having a 5% weight loss temperature of 250 ° C. or more and a conductive agent.
The laminated piezoelectric actuator according to any one of the preceding claims.
伸度１０％以上の導電性接着剤で形成されていることを
特徴とする請求項１乃至３のうちいずれかに記載の積層
型圧電アクチュエータ。4. The belt-like external electrode has an elastic modulus of 20 GPa or less.
4. The multilayer piezoelectric actuator according to claim 1, wherein the multilayer piezoelectric actuator is formed of a conductive adhesive having an elongation of 10% or more.
またはメッシュ状の導電部材とから形成されていること
を特徴とする請求項１または２記載の積層型圧電アクチ
ュエータ。5. The multilayer piezoelectric actuator according to claim 1, wherein the belt-like external electrode is formed of a conductive adhesive and a thin plate or mesh conductive member.
減少温度を有する樹脂と導電剤とを含有するか、もしく
は弾性率２０ＧＰａ以下、伸度１０％以上であることを
特徴とする請求項５記載の積層型圧電アクチュエータ。6. The conductive adhesive contains a resin having a 5% weight loss temperature of 250 ° C. or more and a conductive agent, or has an elastic modulus of 20 GPa or less and an elongation of 10% or more. A multilayer piezoelectric actuator according to claim 5.
Priority Applications (1)
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|---|---|---|---|
| JP2000296932A JP2002111088A (en) | 2000-09-28 | 2000-09-28 | Multilayer piezoelectric actuator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000296932A JP2002111088A (en) | 2000-09-28 | 2000-09-28 | Multilayer piezoelectric actuator |
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| Publication Number | Publication Date |
|---|---|
| JP2002111088A true JP2002111088A (en) | 2002-04-12 |
Family
ID=18779125
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|---|---|---|---|
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| Country | Link |
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| JP (1) | JP2002111088A (en) |
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|---|---|---|---|---|
| JP2005243677A (en) * | 2004-02-24 | 2005-09-08 | Kyocera Corp | Stacked electronic component and its manufacturing method, and injection apparatus using the same |
| JP2006005314A (en) * | 2004-06-21 | 2006-01-05 | Denso Corp | Multilayer piezoelectric element and injector using the same |
| JP2006066837A (en) * | 2004-08-30 | 2006-03-09 | Denso Corp | Laminated piezoelectric element and its manufacturing method, and conductive adhesive |
| US7061162B2 (en) | 2003-03-12 | 2006-06-13 | Denso Corporation | Laminated piezoelectric element |
| JP2006203245A (en) * | 2006-03-27 | 2006-08-03 | Kyocera Corp | Laminated piezoelectric device and manufacturing method |
| JP2010522973A (en) * | 2007-03-27 | 2010-07-08 | 京セラ株式会社 | LAMINATED PIEZOELECTRIC ELEMENT, INJECTION DEVICE USING THE SAME, AND METHOD FOR PRODUCING LAMINATED PIEZOELECTRIC ELEMENT |
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2000
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7061162B2 (en) | 2003-03-12 | 2006-06-13 | Denso Corporation | Laminated piezoelectric element |
| JP2005243677A (en) * | 2004-02-24 | 2005-09-08 | Kyocera Corp | Stacked electronic component and its manufacturing method, and injection apparatus using the same |
| JP2006005314A (en) * | 2004-06-21 | 2006-01-05 | Denso Corp | Multilayer piezoelectric element and injector using the same |
| JP2006066837A (en) * | 2004-08-30 | 2006-03-09 | Denso Corp | Laminated piezoelectric element and its manufacturing method, and conductive adhesive |
| JP4706209B2 (en) * | 2004-08-30 | 2011-06-22 | 株式会社デンソー | Multilayer piezoelectric element, manufacturing method thereof, and conductive adhesive |
| DE102005040900B4 (en) * | 2004-08-30 | 2015-03-12 | Denso Corporation | Stacked piezoelectric element, its manufacturing method and electrically conductive adhesive |
| JP2006203245A (en) * | 2006-03-27 | 2006-08-03 | Kyocera Corp | Laminated piezoelectric device and manufacturing method |
| JP4498299B2 (en) * | 2006-03-27 | 2010-07-07 | 京セラ株式会社 | Manufacturing method of multilayer piezoelectric element |
| JP2010522973A (en) * | 2007-03-27 | 2010-07-08 | 京セラ株式会社 | LAMINATED PIEZOELECTRIC ELEMENT, INJECTION DEVICE USING THE SAME, AND METHOD FOR PRODUCING LAMINATED PIEZOELECTRIC ELEMENT |
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