JP2004200382A - Piezoelectric / electrostrictive film type element - Google Patents

Abstract

An object of the present invention is to achieve excellent durability, while suppressing a decrease in an initial bending displacement amount of a driving unit due to an arrangement of a displacement transmitting unit, while hardly reducing the bending displacement amount with respect to the initial bending displacement amount even after long-term continuous use. Provided is a piezoelectric / electrostrictive film type device.
A vibrating part (20) made of a ceramic thin plate, a fixed part (22) made of ceramics for supporting the vibrating part (20), and a piezoelectric / electrostrictive layer (27) provided on the vibrating part (20). A drive unit 28 having at least a pair of electrodes 26a and 26b provided in contact with each other, and a material provided on the drive unit 28 and having a hardness lower than that of a material constituting the piezoelectric / electrostrictive layer 27 of the drive unit 28 In the piezoelectric / electrostrictive film element 10 including the displacement transmitting unit 30, an intermediate layer 29 having a specific hardness is provided between the driving unit 28 and the displacement transmitting unit 30.
[Selection diagram] Fig. 1

Description

【００７８】
【化２】

【００７９】
【化３】

【００８０】上記式（１）〜（３）中、Ｒ¹は炭素数１〜１６のフルオロアルキル基又はパーフルオロアルキル基を示し、Ｒ²は炭素数１〜１６のアルキル基、ハロゲン化アルキル基、アリール基、アルキルアリール基、アリールアルキル基、アルケニル基、またはアルコキシ基、水素原子あるいはハロゲン原子を示す。また、ａは１〜１２の整数、ｂは０〜２４の整数、ｃは０〜２４の整数を示し、ｂ＋ｃは２ａである。
【００８１】他方、当該ハイブリッド材料に含有する無機粒子としては、例えば、Ａｌ₂Ｏ₃、Ｂ₂Ｏ₃、ＴｉＯ₂、ＺｒＯ₂、ＳｎＯ₂、ＣｅＯ₂、Ｐ₂Ｏ₅、Ｓｂ₂Ｏ₃、Ｓｂ₂Ｏ₅、ＭｏＯ₃、ＺｎＯ、ＷＯ₃、ＣａＦ₂、ＮａＦ、ＮａＡｌＦ₅、ＭｇＦ、及びＳｉＯ₂からなる群から選ばれる少なくとも１種を挙げることができ、中でも、ＳｉＯ₂を主成分とするものが好ましく、ＳｉＯ₂を主成分とし、Ａｌ₂Ｏ₃、Ｂ₂Ｏ₃、ＴｉＯ₂、ＺｒＯ₂、ＳｎＯ₂、ＣｅＯ₂、Ｐ₂Ｏ₅、Ｓｂ₂Ｏ₃、Ｓｂ₂Ｏ₅、ＭｏＯ₃、ＺｎＯ、及びＷＯ₃からなる群から選ばれる少なくとも１種を含有するものがより好ましい。なお、ＳｉＯ₂とシリカ以外の無機酸化物のモル比（シリカ以外の無機酸化物／ＳｉＯ₂）は、０.０００１〜１．０の範囲であることが好ましい。
【００８２】当該無機粒子の粒径は、中間層の振動伝達性や、変位伝達部における駆動部の振動に対する応答性に影響するため、これら特性の最適化の観点から、平均粒径が５ｎｍ〜１μｍのものが好ましく、平均粒径が１０ｎｍ〜２００ｎｍのものがより好ましい。
【００８３】また、当該無機粒子としては、２峰性の粒度分布を有するものとしてもよい。このような無機粒子を含有する中間層とすると、大粒径の無機粒子間の空隙を、小粒径の無機粒子で充填して中間層中の無機粒子の体積分率を上げることができ中間層の硬度をより高くすることができ、中間層のよりいっそうの薄膜化が可能となる。
【００８４】２峰性の粒度分布を有する無機粒子としては、大粒径の無機粒子間の空隙に小粒径の無機粒子を効果的に充填できる点で、２つのピークの間に存在する変曲点に対応する粒径より大きな大粒径無機粒子の平均粒径（Ｃ）と、変曲点の粒径より小さな小粒径無機粒子の平均粒径（Ｄ）との比（Ｄ／Ｃ）が、０．０５〜０．７のものが好ましく、０．１〜０．５のものがより好ましい。また、当該２峰性の粒度分布を有する無機粒子は、同様の点で大粒径無機粒子の質量（Ｅ）と小粒径無機粒子の質量（Ｆ）との比（Ｆ／Ｅ）が、０．０５〜０．７のものが好ましく、０．１〜０．５のものがより好ましい。
【００８５】本発明において用いられるハイブリッド材料は、上記各種高分子化合物からなるマトリックスと、上記各種無機粒子を組み合わせたものが可能であるが、中でも、ポリシロキサンポリマーを主成分とするマトリックスと、シリカを主成分とする無機粒子からなるハイブリッド材料が好ましく、フッ素置換アルキル基を有するポリシロキサンポリマーを主成分とするマトリックスと、シリカを主成分としＡｌ₂Ｏ₃、Ｂ₂Ｏ₃、ＴｉＯ₂、ＺｒＯ₂、ＳｎＯ₂、ＣｅＯ₂、Ｐ₂Ｏ₅、Ｓｂ₂Ｏ₃、Ｓｂ₂Ｏ₅、ＭｏＯ₃、ＺｎＯ、及びＷＯ₃からなる群から選ばれる少なくとも１種を含有する無機粒子からなるハイブリッド材料が特に好ましい。
【００８６】当該ハイブリッド材料で中間層２９を構成すると、耐熱性、耐水性、耐薬品性、及び撥水性等の点で優れるとともに、駆動部や変位伝達部との密着性にも優れ、かつ薄層化により駆動部に対する拘束も低減することができる。
【００８７】本発明における中間層２９は、変位伝達部への振動伝達性に及ぼす影響を抑えながら駆動部に対する迅速な応答性を得るために、上記硬度以外に層の厚さについても考慮することが好ましい。具体的には、中間層２９の厚さが０．１〜１０μｍであることが好ましく、０．１〜５μｍであることがより好ましく、０．１〜２μｍであることが特に好ましい。中間層の厚さが、この範囲であれば、駆動部２８に対する拘束が小さく、駆動部２８の屈曲変位量を殆ど低下させることなく、変位伝達部の駆動部に対する応答性を高めることができる。
【００８８】また、中間層２９の厚さは、同様の点から、振動部２０及び駆動部２８の合計厚さに対して１／１５以下であることが好ましく、１／２０以下であることがより好ましく、１／３０以下であることが特に好ましい。
【００８９】図１に示すように、本発明における中間層２９は、少なくとも、駆動部２８及び変位伝達部３０の対向する両面において、相互に対応する部分を含んで設けられていればよい。但し、圧電／電歪膜型素子の耐熱性、耐水性、耐薬品性、及び撥水性等を向上させるには、更に駆動部２８の外表面全体を覆って中間層２９を設けてもよく、図２に示すように、更に、駆動部２８の外表面全体、及び振動部２０の駆動部を設けた面全体を覆って中間層２９を設けることが耐熱性、耐水性、耐薬品性、及び撥水性等をより向上させることができる他、圧電／電歪膜型素子の製造工程が簡易となり、駆動部２８や変位伝達部３０の形状や大きさのばらつきにも柔軟に対応できる点で好ましい。
【００９０】なお、図２に示すように、当該中間層２９を、駆動部２８及び変位伝達部３０の対向する両面において相互に対応する部分以外にも設ける場合には、当該駆動部２８及び変位伝達部３０の対向する両面において相互に対応する部分以外に存する中間層２９の厚さは、前述した好適な中間層２９の厚さより厚くしたりより薄くしたりすることができる。
【００９１】本発明における中間層２９の形成方法としては、例えば、無機粒子と、所望の重合性オリゴマーとを分散液中に混合した塗布液を圧電／電歪層２７に塗布した後、乾燥する方法を挙げることができる。この方法によれば、中間層２９の形成に伴う乾燥工程において、中間層２９の収縮が小さく、中間層２９や駆動部２８等のクラックの発生を抑制できる。
【００９２】本発明においては、当初から、前述したハイブリッド材料中のマトリックスを構成する高分子化合物を分散液中に混合した塗布液を用いることも可能であるが、緻密で均一な中間層を形成するためには、所望の高分子化合物に対応する重合性オリゴマーを分散液中に混合したものが好ましい。
【００９３】また、当該塗布液に用いる分散媒としては、例えば、水、メタノール、エタノール、プロパノール、イソプロピルアルコール、ブタノール、又はアセトン等の極性分散媒が均一な分散液が得られやすい点で好ましい。
【００９４】また、当該分散媒中に混合する無機粒子としては、前述した成分、粒径、粒度分布のものを用いればよい。また、本発明においてマトリックスを形成するために用いられる重合性オリゴマーとしては、前述したアクリル樹脂等のビニル重合体、エポキシ樹脂やポリウレタン等の付加重合体、ポリエステル、ポリカーボネート等の縮合重合体、又は有機ケイ素化合物の重合体であるポリシロキサンポリマーに対応する重合性オリゴマーを挙げることができる。
【００９５】また、フッ素置換アルキル基を有するポリシロキサンポリマーに対応する重合性モノマー又は重合性オリゴマーとしては、下記式（４）又は（５）で表されるフルオロアルキル基を有する含フッ素シリコーン系化合物を挙げることができる。
【００９６】
【化４】

【００９７】
【化５】

【００９８】上記式（４）、式（５）中、Ｒ¹は炭素数１〜１６（好ましくは３〜１２）のフルオロアルキル基又はパーフルオロアルキル基を示し、Ｒ²〜Ｒ⁷は炭素数１〜１６（好ましくは１〜４）のアルキル基、炭素数１〜６（好ましくは１〜４）のハロゲン化アルキル基、炭素数６〜１２（好ましくは６〜１０）のアリール基、炭素数７〜１４（好ましくは７〜１２）のアルキルアリール基、アリールアルキル基、炭素数２〜８（好ましくは２〜６）のアルケニル基、炭素数１〜６（好ましくは１〜３）のアルコキシ基、水素原子、又はハロゲン原子を示す。また、ａは１〜１２の整数、ｂは０〜２４の整数、ｃは０〜２４の整数を示し、ｂ＋ｃは２ａである。
【００９９】具体的には、ヘプタデカフルオロデシルメチルジメトキシシラン、ヘプタデカフルオロデシルトリクロロシシラン、ヘプタデカフルオロデシルトリメトキシシラン、トリフルオロプロピルトリメトキシシラン、トリデカフルオロオクチルトリメトキシシラン、又はメトキシジシラン化合物等を挙げることができる。
【０１００】なお、上記重合性オリゴマーは、後述する乾燥工程で、脱水若しくは脱アルコール反応等で縮重合し、中間層のマトリックスを構成する所望の高分子化合物となる。
【０１０１】本発明において、重合性オリゴマーと無機粒子の配合比率は、各成分の種類に応じて適切な範囲とすることが好ましい。例えば、重合性オリゴマーとして、フッ素置換アルキル基を有するポリシロキサンポリマーに対応する重合性モノマーを用いる場合には、重合性オリゴマー１００重量部に対し、無機粒子が０．１〜３００重量部の割合となるように塗布液中に含有させることが好ましく、１〜１００重量部の割合となるように塗布液中に含有させることがより好ましい。
【０１０２】本発明において、塗布液を圧電／電歪層２７に塗布する方法としては、ディッピング法、スプレー法、又はスピンコート法等のコート方法を挙げることができるが、中間層の均一化、薄層化が容易である点で、スピンコート法が好ましい。
【０１０３】また、均一な中間層２９を設けるには、溶液粘度が１０００ｃＰ以下の塗布液を用いることが好ましく、溶液粘度が３００ｃＰ以下の塗布液を用いることがより好ましく、溶液粘度が５０ｃＰ以下の塗布液を用いることが特に好ましい。
【０１０４】また、当該中間層２９を、振動部２０及び駆動部２８の合計厚さに対して１／１５以下の厚さ、より好ましくは１／３０以下の厚さで設けるには、上記スピンコート法で、塗布液を滴下直後、回転速度を１５００ｒｐｍ以上として行うことが好ましい。なお、ディッピング法により、上記コーティング剤を圧電／電歪層全体に塗布する場合でも、圧縮空気を吹付ける工程を行うことで上記厚さの中間層２９を設けることはできるが、容易に薄くて均一な層を形成することができる点で、スピンコート法により形成することが好ましい。
【０１０５】本発明においては、上記塗布液を塗布した後、乾燥により中間層２９を形成するが、その乾燥は、塗布液の組成に応じて適切な条件を選択することが好ましい。例えば、塗布液中に、前述したマトリックスの構成材料であるアクリル樹脂等のビニル重合体、エポキシ樹脂やポリウレタン等の付加重合体、ポリエステル、又はポリカーボネート等の縮合重合体に対応する重合性オリゴマーを混合する場合であれば、上記塗布液を塗布した後に、室温で放置して乾燥を行えばよい。
【０１０６】一方、塗布液中に、前述したマトリックスの構成材料であるポリシロキサンポリマーに対応する重合性オリゴマーを混合する場合であれば、上記塗布液を塗布した後には、室温で１０分以上放置して溶剤の大部分を除去した後、６００℃／ｈｒ以下の速度で、所望の温度まで雰囲気温度を上昇させて加熱による乾燥を行うことが好ましい。
【０１０７】塗布後直ちに加熱して乾燥したり、急速に温度を上昇させて乾燥すると、塗布液中の溶剤の急速な蒸発により、塗布液が急速に収縮し、中間層中にクラックが発生したり、電圧／電歪層との界面に剥離を生ずることがある。
【０１０８】また、当該加熱による乾燥は、６０〜１２０℃で行うことが好ましく、１００〜１２０℃で行うことがより好ましい。１２０℃を超える温度で乾燥すると、上記室温放置の理由と同様に塗布液中の溶剤の急速な蒸発により、塗布液が急速に収縮し、中間層中にクラックが発生したり、電圧／電歪層との界面に剥離を生ずることがある。一方、上記加熱温度より低い温度で乾燥すると、有機溶剤とともに、これに溶存する水分の除去が不充分となる。
【０１０９】ポリシロキサンポリマーに対応する重合オリゴマーを混合した塗布液を塗布した場合には、更に、上記乾燥後、連続して又は別工程で、より高温の加熱による硬化処理を行うことが好ましい。具体的には、７００℃以下の温度で加熱することが好ましく、６００℃以下の温度で加熱することがより好ましく、５００℃未満の温度で加熱することが更に好ましく、４５０℃未満の温度で加熱することが特に好ましい。
【０１１０】当該加熱による硬化処理の温度が、上記温度範囲を超えると、中間層中のＳｉ等の成分が圧電／電歪層を構成する材料と反応して、圧電／電歪層の性能を低下させ、場合によっては圧電／電歪層に欠陥を生じさせるため、絶縁破壊、機械的破壊等を生じることがある。また、中間層中の有機成分の分解が起こり、中間層にクラックを生じることがある。
【０１１１】なお、本発明においては塗布液中の重合性オリゴマーと無機粒子の構成比等を調製することにより、又は硬化処理の際に加熱温度を調整して、シロキサン結合（−Ｓｉ−Ｏ−）等の結合強度を変化させることにより、硬度等の機械的特性（無機粒子の構成比が大きい程、又は硬化処理の際の温度を高くするほど、硬度が上昇する。）、及び撥水性等の化学的特性を最適化することができる。
【０１１２】以上、本発明の圧電／電歪膜型素子について説明したが、本発明の圧電／電歪膜型素子は、その変位動作を利用して、例えば、表示素子や、光スイッチとして用いることができる。具体的には、例えば、図１３に示すように、変位伝達部３０（３０ａ、３０ｂ）を、光路変更手段（図示せず）や光反射手段（図示せず）を含んで構成させ、かつ当該変位伝達部３０（３０ａ）を光導波板２００に近接する位置で配設する。そして、電気信号に応じて駆動部２８を動作させることで光反射作用等を有する変位伝達部３０（３０ａ）を、光導波板に接触・離隔させることで、所望の表示や光路の切り替えを行うことができる（図中に、光を１８０で示す。）。なお、具体的な内容については、特開平１０−７８５４９号公報に記載されているので参考までにここに引用する。また、本発明においては、このような素子において、所定の中間層を設けることで、変位伝達部を駆動部の屈曲変位に的確に追従させて動作させることができるためより高速の応答が可能となる。
【０１１３】
【実施例】以下、本発明を、実施例により更に具体的に説明するが、本発明はこれら実施例に何ら限定されるものではない。なお、各実施例、及び比較例についての評価は以下のようにして行った。
【０１１４】
（評価方法）
（１）屈曲変位
実施例及び比較例で得られた圧電／電歪膜型素子に、室温下、３ｋＶ／ｍｍの電界を印加した際の変位量をレーザードップラー振動計により測定した。数値は、複数の駆動部で得られた数値の平均値で示した。
【０１１５】
（２）ビッカース深さ
実施例及び比較例で得られた圧電／電歪膜型素子の、中間層、圧電／電歪層、電極及び基体について、微小硬度計圧子を用いて以下の条件で押込み深さを測定した。
【０１１６】
▲１▼ 装置：島津ダイナミック超微小硬度計ＤＵＨ−２０１
▲２▼ 圧子：対面角１３６°のビッカース形状を有するダイヤモンド製の圧子
▲３▼ 試験モード：負荷−除荷試験（荷重を一定速度で増加させていき、一時保持後、一定速度で荷重を減らしていく試験）
▲４▼ 押込み荷重：１ｇｆ
▲５▼ 押込み速度：０．１４５ｇｆ／ｓｅｃ
▲６▼ 荷重保持時間：１０ｓｅｃ
▲７▼ その他：被検対象物（電極、圧電／電歪層、及び基体）が、微小である、或いは曲面又は凹凸部を有する等の理由でビッカース圧子を適切な条件で押込めない場合には、ビッカース圧子を適切な条件で押込める形状の同材料を被検対象物として測定する。
【０１１７】
（３）無機粒子の平均粒径、及び粒度分布
実施例及び比較例で用いた無機粒子を、イソプロパノールに分散させた状態で、大塚電子（株）社製、ダイナミック光散乱光度計ＤＳＬ７０００を用いて、動的光散乱法により測定した。
【０１１８】
（実施例１）
まず、Ｙ₂Ｏ₃で安定化されたＺｒＯ₂からなり、大きさが６０ｍｍ×６０ｍｍで、直径１００μｍの小さな貫通孔を１．５ｍｍピッチで有する、厚さ１５０μｍの基板層を作製した。また、同材料からなり、大きさが６０ｍｍ×６０ｍｍで、１．０ｍｍ×１．０ｍｍの空所を１．５ｍｍピッチで有する厚さ１０μｍのスペーサ層と、同材料からなり、大きさが６０ｍｍ×６０ｍｍで、厚さが１０μｍの薄板層とを作製した。次いで、外延を揃えて、基板層、スペーサ層、薄板層の順に積層し、焼成一体化した（薄板層が、振動部に相当し、スペーサ層と基板層が固定部に相当する。）。
【０１１９】次いで、振動部上のスペーサ層の各空所に対応する位置に、それぞれ白金からなる下部電極（寸法：０．６×０．６ｍｍ、厚さ：３．０μｍ）をスクリーン印刷法により形成し、１３００℃、２時間の熱処理により振動部と一体化した。次いで、下部電極上に、ジルコン酸鉛とチタン酸鉛とマグネシウムニオブ酸鉛の３成分を主成分とする圧電材料を０．８×０．８ｍｍの範囲（下部電極を含むより広い範囲）で積層した後、圧電材料と同一組成の雰囲気制御材料を、容器内に共存させた状態で、１２７５℃、２時間熱処理して厚さ２０μｍの圧電層を設けた。次いで、圧電層の上に、金からなる上部電極を、スクリーン印刷法により、０．６×０．６ｍｍの範囲で厚さ０．２μｍで形成した後、６００℃で熱処理した。なお、以上の工程で、振動部上に１．５ｍｍの間隔で、３０×３０個（９００個／１基体）の駆動部が設けられた。
【０１２０】次いで、得られたものを試料台に固定し、非晶質シリカ粒子をイソプロピルアルコール中に分散したコロイダルシリカ（固形分濃度２０質量％）３０質量％と、イソプロピルアルコール及び水からなる混合分散媒中に、テトラエトキシシラン及びメチルエトキシシランの等モル混合物を重合性オリゴマー溶液全量中２０質量％含有させた重合性オリゴマー溶液７０質量％とを混合した塗付液（商品名：セラメートＣ−５１３、触媒化成工業（株）社製、粘度（２５℃）：２０ｃＰ以下、ｐＨ（２５℃）：３〜５、液比重：０．９〜１．０ｇ／ｍｌ）を、各駆動部及び基体の外表面全体にスピンコート法により塗布した。この際、試料台は、最初５００ｒｐｍで回転し、塗布液を滴下した直後、回転数を２０００ｒｐｍまで上昇させて３０秒間保持した後、回転を停止した。
【０１２１】回転停止後、塗布液を塗布したものを、室温で３０分放置し、その後、昇温速度２００℃／ｈで昇温して８０〜１２０℃の間で１時間温度を保持した後、連続的に３００℃まで昇温して、同温度で１時間硬化処理を行い厚さ約０．５μｍの中間層を形成した。
【０１２２】最後に、中間層上に、スクリーン印刷法により、変性エポキシオリゴマーを主成分とする塗布液を塗布した後、１３０℃、１時間で硬化して変位伝達部を形成し、圧電／電歪膜型素子を製造した。
【０１２３】得られた圧電／電歪膜型素子の各構成物のビッカース圧子押込み深さは、振動部が０．１８μｍ、圧電／電歪層が、０．２７μｍ、中間層が０．８７μｍであった。また、中間層の厚さは、０．５μｍであった。
【０１２４】
（比較例１）
コロイダルシリカと重合性オリゴマー溶液とを混合した塗布液を塗布して中間層を設けることなく、駆動部上に、変位伝達部を形成したこと以外は実施例１と同様にして圧電／電歪膜型素子を製造した。
【０１２５】
（評価）
図１４に示すように、所定の中間層を設けなかった比較例１の圧電／電歪膜型素子では、各駆動部の初期屈曲変位量の平均が、約２．０μｍであったものの、パルス数２億回程度で、屈曲変位量の平均が初期屈曲変位量の平均に対して、８０％程度まで低下し、その後もパルス数が大きくなるにしたがって低下し、パルス数２０億回で屈曲変位量の平均が初期の屈曲変位量の平均に対して、７０％程度まで低下した。
【０１２６】これに対して、中間層を設けた実施例１の圧電／電歪膜型素子では、初期屈曲変位量の平均が、約１．９μｍと比較例１の圧電／電歪膜型素子とほぼ同様であり、パルス数が多くなっても、屈曲変位の変化が殆ど無く、パルス数２０億回でも、屈曲変位量の平均が初期の屈曲変位量の平均に対して、９８％に維持されていた。
【０１２７】
【発明の効果】以上説明したように、本発明によれば、変位伝達部の配設による駆動部の初期屈曲変位量の低下を抑制しながら、長期間の継続的使用によっても初期屈曲変位量に対する屈曲変位量の低減が殆ど無い、耐久性に優れる圧電／電歪膜型素子を提供することができる。
【図面の簡単な説明】
【図１】本発明の一の実施の形態を示す一部断面図である。
【図２】本発明の他の実施の形態を示す一部断面図である。
【図３】本発明の更に他の実施の形態について、固定部の一部、振動部、及び駆動部を示す一部断面図である。
【図４】本発明の更に他の実施の形態について、固定部の一部、振動部、及び駆動部を示す一部断面図である。
【図５】本発明の更に他の実施の形態について、固定部の一部、振動部、及び駆動部を示す一部断面図である。
【図６】図５の一部上面図である。
【図７】本発明の更に他の実施の形態について、固定部の一部、振動部、及び駆動部を示す一部断面図である。
【図８】本発明の更に他の実施の形態について、固定部の一部、振動部、及び駆動部を示す一部断面図である。
【図９】本発明の更に他の実施の形態について、固定部の一部、振動部、及び駆動部を示す一部断面図である。
【図１０】本発明の更に他の実施の形態について、固定部の一部、振動部、及び駆動部を示す一部断面図である。
【図１１】本発明の更に他の実施の形態を示す一部断面図である。
【図１２】本発明の更に他の実施の形態を示す一部断面図である。
【図１３】本発明の圧電／電歪膜型素子を適用した表示素子の一例を模式的に示す一部断面図である。
【図１４】本発明の実施例と比較例の圧電／電歪膜型素子について、パルス数に対する屈曲変位の変化率を示すグラフである。
【符号の説明】
１０…圧電／電歪膜型素子、１１…圧電／電歪膜型素子、１２Ａ…基板層、１２Ｂ…スペサー層、１２Ｃ…薄板層、１４…空所、１８、４４…貫通孔、２０…振動部、２２…固定部、２５（２５ａ〜２５ｄ）…電極、２６（２６ａ〜２６ｆ）…電極、２７（２７ａ〜２７ｄ）…圧電／電歪層、２８…駆動部、２９…中間層、３０（３０ａ、３０ｂ）…変位伝達部、１８０…光、２００…光導波板。[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric / electrostrictive film type element, and more particularly, to a piezoelectric / electrostrictive element for mutually converting an electric signal and an external force such as vibration or displacement operation on a ceramic substrate. The present invention relates to a piezoelectric / electrostrictive film type device including a strainer, a drive unit having an electrode electrically connected to the strainer, and a displacement transmission unit transmitting vibration from the drive unit.
[0002]
2. Description of the Related Art A piezoelectric / electrostrictive film type element has a function of mutually converting an electric signal and an external force such as vibration and displacement operation, and can control a minute displacement and a high electric / electrical force. In recent years, it has excellent characteristics such as mechanical conversion efficiency, high-speed response, high durability, and low power consumption. Therefore, in recent years, various types of sensors that convert display elements, optical switches, or vibration and displacement operations into electrical signals. And so on.
The piezoelectric / electrostrictive film element includes a vibrating portion made of a ceramic thin plate, a fixed portion made of ceramics supporting the vibrating portion, an electrode provided on the vibrating portion, and a piezoelectric / electrostrictive device. Generally, a device including a driving unit in which a strained layer is laminated is provided. Such a piezoelectric / electrostrictive film type element further includes a pixel structure and an optical path changing body on a driving unit according to various applications, so that the pixel structure and the optical path changing body are connected to the driving unit. A display element, an optical switch, or the like that contacts or separates an optical waveguide plate that transmits light from a light source according to vibration, and transmits light of a desired wavelength to a specific position or switches to a desired optical path. (For example, Patent Document 1).
Incidentally, in a piezoelectric / electrostrictive film type element applied to a display element, an optical switch or the like, an object is to levelly transmit a vibration generated in a driving section to a pixel structure or an optical path changing body. As an example, a displacement transmitting unit is provided between a driving unit and a pixel structure or an optical path changing body (for example, Patent Document 2).
In general, the displacement transmitting section is provided directly on the driving section in order to meet the demand for high-density elements while ensuring driving characteristics such as response frequency and amplitude. For example, Patent Document 2).
Further, as a conventional piezoelectric / electrostrictive film type element, in order to minimize the constraint on a driving part which bends and vibrates by itself, a displacement transmitting part is made of a small-hardness epoxy resin or acrylic resin. A resin composed of an organic resin such as a resin, a silicone resin, or a polyolefin resin has been developed (for example, Patent Document 3).
However, in such a piezoelectric / electrostrictive film type element provided with a displacement transmitting portion made of a material having a small hardness, the displacement of the driving portion gradually decreases due to continuous driving for a long time. However, in a piezoelectric / electrostrictive film type element having no displacement transmitting section, a phenomenon that was not observed at all occurs, and this is a new problem.
[0008]
[Patent Document 1]
JP-A-7-287176
[Patent Document 2]
JP 2000-155536 A
[Patent Document 3]
WO 01/48535 pamphlet
[0009]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to suppress a decrease in the amount of initial bending displacement of a driving section while maintaining a long period of time. An object of the present invention is to provide a piezoelectric / electrostrictive film element having excellent durability, which hardly reduces the amount of bending displacement relative to the amount of initial bending displacement in a driving section even by dynamic driving.
[0010]
Means for Solving the Problems The inventor of the present invention has intensively studied the causes to solve the above-mentioned problems, and found that the displacement transmitting portion has some form in a long-term continuous vibration state. It has been found that they act on the piezoelectric / electrostrictive layer to change the internal stress of the piezoelectric / electrostrictive layer, thereby generating microcracks and changing the polarization state. As a result of various studies, the present inventor found that the generation of microcracks and changes in the polarization state caused the displacement transmission section to be made of a material having a hardness far different from the ceramics constituting the piezoelectric / electrostrictive layer of the drive section. Was found to be due to what had been done.
Therefore, the present inventor has specified a material such as a ceramic constituting the piezoelectric / electrostrictive layer of the driving section and a resin constituting the displacement transmitting section between the driving section and the displacement transmitting section. When an intermediate layer made of a material having a hardness of 5 mm is provided, not only is there little reduction in the amount of bending displacement relative to the amount of initial bending displacement even after continuous use for a long time, The inventors have found that the reduction in the amount of bending displacement can be suppressed to about the same degree as that of a conventional piezoelectric / electrostrictive film element having no intermediate layer, and have completed the present invention.
That is, the present invention provides a vibrating portion made of a ceramic thin plate, a fixed portion made of ceramics supporting the vibrating portion, a piezoelectric / electrostrictive layer, and at least one pair of piezoelectric / electrostrictive layers provided in contact with the piezoelectric / electrostrictive layer. A piezoelectric / electrode comprising: a drive unit having electrodes and provided on the vibration unit; and a displacement transmission unit provided on the drive unit and made of a material having a lower hardness than a material constituting the piezoelectric / electrostrictive layer of the drive unit. A piezoelectric / electrostrictive film element is provided, which is a strained film element, wherein an intermediate layer having a specific hardness is provided between a driving unit and a displacement transmitting unit.
Here, the "hardness" in the present specification is a diamond indenter having a face-to-face angle of 136 °, and is determined by the indentation depth when the macro Vickers load is 1 gf and the indentation speed is 0.145 gf / sec. Means hardness.
In the present invention, it is preferable that the intermediate layer is made of a material having a lower hardness than the material forming the piezoelectric / electrostrictive layer in the driving section and having a higher hardness than the material forming the displacement transmitting section.
In the present invention, the depth of the intermediate layer into which the micro-Vickers indenter is pressed (hereinafter, may be abbreviated simply as “Vickers depth”) is the same as that of the material constituting the piezoelectric / electrostrictive layer. It is preferably 1 to 5 times the Vickers depth.
The intermediate layer is preferably made of a hybrid material in which silica particles are dispersed in a matrix containing a polysiloxane polymer as a main component. Further, the thickness of the intermediate layer is preferably 0.1 to 5 μm.
In the present invention, it is preferable that at least one of the electrodes is provided in contact with the vibrating portion and the piezoelectric / electrostrictive layer. The electrode provided in contact with the vibrating portion and the piezoelectric / electrostrictive layer may be a platinum group simple substance, an alloy of platinum group simple substance with gold and / or silver, an alloy of platinum group, or a platinum group different group. Those comprising alloys with more than one kind of metal, gold and / or silver are preferred.
Further, in the present invention, it is preferable that the drive section is directly bonded to the vibration section by heat treatment of at least the piezoelectric / electrostrictive layer to be integrated with the base.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the piezoelectric / electrostrictive film type device of the present invention will be described specifically, but the present invention is not construed as being limited to these, and the present invention is not limited thereto. Various changes, modifications, and improvements can be made based on the knowledge of those skilled in the art without departing from the scope. In the following, description will be made mainly on the embodiment of the piezoelectric film element, but the same applies to the electrostrictive film element.
As shown in FIGS. 1 and 2, the piezoelectric / electrostrictive film type element 10 of the present invention comprises a vibrating portion 20 made of a ceramic thin plate, a fixed portion 22 made of ceramics for supporting the vibrating portion 20, and A drive unit 28 provided on the vibration unit 20 and having a piezoelectric / electrostrictive layer 27 and at least a pair of electrodes 26a and 26b provided in contact with the piezoelectric / electrostrictive layer 27; And a displacement transmitting section 30 made of a material having a hardness smaller than that of the material constituting the piezoelectric / electrostrictive layer 27 of the driving section 28. A specific hardness between the driving section 28 and the displacement transmitting section 30 is provided. The material, preferably, a material having a higher hardness than the material forming the displacement transmitting unit 30, more preferably, a material having a lower hardness than the material forming the piezoelectric / electrostrictive layer 27 of the driving unit 28, and more preferably than the material forming the displacement transmitting unit 30. Material with high hardness It is characterized in that an intermediate layer 29 made.
The piezoelectric / electrostrictive film type element 10 of the present invention can provide the piezoelectric / electrostrictive device provided by the displacement transmitting unit 30 even when the driving unit 28 is driven at a high speed for a long time. The change in the internal stress of the strained layer 27 is suppressed, and the phenomena of changing the polarization state of the piezoelectric / electrostrictive layer 27 and generating microcracks in the piezoelectric / electrostrictive layer 27 can be greatly improved. Therefore, according to the piezoelectric / electrostrictive film element of the present invention, a desired amount of bending displacement can be maintained for a long period of time. In addition, since the piezoelectric / electrostrictive film element of the present invention has an intermediate layer having a hardness in the above specific range, the initial bending displacement is substantially the same as that of a conventional piezoelectric / electrostrictive film element having no intermediate layer. Quantity can be maintained.
According to the present inventor, by providing the intermediate layer 29 having a specific hardness, the change in internal stress applied to the piezoelectric / electrostrictive layer 27 can be greatly reduced by the presence of the intermediate layer 29. It is considered that the followability of the displacement transmitting unit 30 to the operation of the driving unit 28 is enhanced, and the operation of the displacement transmitting unit 30 is always synchronized with the operation of the driving unit 28. Hereinafter, the piezoelectric / electrostrictive film type device of the present invention will be specifically described for each component.
As shown in FIGS. 1 and 2 and the like, the vibrating part 20 of the present invention is made of a ceramic thin plate, and the fixing part 22 of the present invention is a ceramic member that supports the vibrating part 20. The fixed part 22 and the vibrating part 20 usually have an integrated structure, and the thin plate-shaped vibrating part 20 is fixed to the fixed part 22 at a position other than the position where the driving part 28 is provided. Normally, the cavity 14 is provided below the vibrating part 20 corresponding to the position where the driving part 28 is provided.
In the present invention, for example, the vibrating part 20 and the fixed part 22 correspond to the substrate layer 12 A having the through hole 18 having a small diameter, the spacer layer 12 B having the through hole corresponding to the cavity 14, and the vibrating part 20. And a thin plate layer 12C having a desired thickness. At this time, the substrate layer 12A can also function as a wiring substrate by providing a wiring leading to the electrodes 26a and 26b on the lower surface of the substrate layer 12A, in addition to functioning as a reinforcing substrate. These layers 12A to 12C constituting the vibrating part 20 and the fixed part 22 may be fired and integrated at the same time for each layer, may be fired and integrated at the time each layer is sequentially stacked, or may be fired individually for each layer. After that, they may be laminated and integrated.
In the present invention, the thickness of the spacer layer 12B is not particularly limited. For example, the thickness can be determined according to the purpose of use of the space 14. However, it is preferable that the driving unit 28 does not have an unnecessarily thick thickness in order to function. For example, the driving unit 28 is thin as shown in FIGS. 1 and 2, and more specifically, corresponds to a displacement of the driving unit 28. Thick ones are preferred.
With such a configuration, the bending of the vibrating portion 20 is easily limited by the substrate layer 12A bonded to the thin spacer layer 12B, and the thin vibrating portion 20 is prevented from being broken against an unintended external force. be able to. Note that the displacement of the driving unit 28 can be stabilized at a specific value by utilizing the effect of limiting the deflection by the substrate layer 12A.
Further, by reducing the thickness of the spacer layer 12B, the thickness of the entire substrate including the vibrating portion 20 and the fixed portion 22 can be reduced, and the bending rigidity can be reduced. When the electrostrictive film-type element is fixed to a separate body, the warpage of the base is corrected, and the reliability of the fixing can be improved.
In addition, by reducing the thickness of the spacer layer 12B, it is possible to reduce the amount of raw materials required for fabricating the fixing portion 22, so that the manufacturing cost of the piezoelectric / electrostrictive film element can be reduced.
From such a viewpoint, in the present invention, the spacer layer 12B preferably has a thickness of 3 to 50 μm, and particularly preferably has a thickness of 3 to 20 μm. On the other hand, it is preferable that the substrate layer 12A be provided with a thickness that can ensure the mechanical strength of the entire base including the vibrating portion 20 and the fixing portion 22, corresponding to the configuration in which the spacer layer 12B is made thin. Specifically, the substrate layer 12A preferably has a thickness of 50 μm or more, and more preferably has a thickness of 80 to 300 μm.
The shape of the surface on which the driving section 28 of the vibrating section 20 is provided is not particularly limited to a rectangular shape, but may be a circle or a polygon other than a quadrangle such as a triangle.
The vibrating part 20 and the fixed part 22 in the present invention may be made of ceramics. However, when the piezoelectric / electrostrictive layer 27 or the electrodes 26a, 26b, etc. It is preferable to use a material that does not deteriorate and has excellent heat resistance and chemical stability. In addition, the vibrating part 20 or the fixed part 22 is preferably an electrically insulating material in order to electrically separate the wiring leading to the lower electrode 26b formed on the vibrating part 20.
Specifically, for example, at least one selected from the group consisting of stabilized zirconium oxide, aluminum oxide, magnesium oxide, titanium oxide, spinel, mullite, aluminum nitride, silicon nitride, and glass is mentioned. Can be. Above all, since the mechanical strength is large and the toughness is excellent, the durability of the vibrating part 20 to which vibration is applied can be improved due to its structure, and the chemical stability is high, and the piezoelectric / electrostrictive layer 27 A material containing stabilized zirconium oxide is preferable because the reactivity with the electrodes 26a and 26b is extremely small.
Examples of the stabilized zirconium oxide include those containing a stabilizer such as calcium oxide, magnesium oxide, yttrium oxide, scandium oxide, ytterbium oxide, cerium oxide, or a rare earth metal oxide. it can. Further, in the case of yttrium oxide or ytterbium oxide, the amount of addition of these stabilizers is preferably 1 to 30 mol%, more preferably 1.5 to 10 mol%. In the case of cerium oxide, 6 to 50 mol% is preferable, and 8 to 20 mol% is more preferable. In the case of calcium oxide or magnesium oxide, the content is preferably 5 to 40 mol%, more preferably 5 to 20 mol%.
Among these stabilizers, those to which yttrium oxide is added are particularly preferable, and the amount of addition in that case is more preferably 2.0 to 6.0 mol%. Further, those containing 0.1 to 5.0 mol% of aluminum oxide are particularly preferable.
The vibrating part 20 or the fixed part 22 may contain components such as silicon oxide and boron oxide contained in clay or the like used as a sintering aid, in addition to the above ceramics. However, if these components are contained excessively, these components react with the material constituting the piezoelectric / electrostrictive layer 27 during firing, and it is difficult to maintain a specific composition of the piezoelectric / electrostrictive layer 27. Which causes the piezoelectric / electrostrictive characteristics to deteriorate. Therefore, in the vibrating part 20 or the fixed part 22 in the present invention, the amount of silicon oxide, boron oxide, or the like contained in the clay or the like is preferably 20% by mass or less in the vibrating part 20 or the fixed part 22, and is preferably 3% by mass or less. Is more preferable.
The ceramic constituting the vibrating portion 20 and the fixed portion 22 preferably has an average crystal grain size of 0.05 to 2.0 μm in order to increase the mechanical strength of the vibrating portion 20. , And more preferably 0.1 to 1.0 μm.
Next, as shown in FIGS. 1 and 2, the driving section 28 of the present invention is provided on the vibrating section 20, and is provided in contact with the piezoelectric / electrostrictive layer 27 and the piezoelectric / electrostrictive layer 27. At least a pair of electrodes 26a and 26b.
As the electrodes 26a and 26b in the present invention, for example, as shown in FIG. 1, a pair of electrodes 26a and 26b on a pair of flat films are laminated on the upper and lower surfaces of a piezoelectric / electrostrictive layer 27. Can be.
However, as shown in FIGS. 5 and 6, a pair of comb-shaped electrodes 26c and 26d are formed on the upper surface of the piezoelectric / electrostrictive layer 27, or as shown in FIG. A pair of comb-shaped electrodes 26c and 26d may be formed on the lower surface of 27.
Further, as shown in FIG. 8, a single flat film-like electrode 26e is formed on the lower surface of the piezoelectric / electrostrictive layer 27, and a plurality of strip-like electrodes are formed on the upper surface of the piezoelectric / electrostrictive layer 27. As shown in FIG. 9, a pair of comb-shaped electrodes 26c and 26d are embedded in the piezoelectric / electrostrictive layer, and the piezoelectric / electrostrictive layers 27a to 27f are divided into a plurality in the direction of the electric field. The electrodes 26c and 26d may be alternately arranged between the respective parts.
As shown in FIG. 10, the driving section 28 of the present invention may have a multilayer structure having a plurality of piezoelectric / electrostrictive layers 27a to 27d. It is preferable that the electrodes 25a to 25e are alternately sandwiched between the electrodes 27a to 27d.
The drive unit 28 shown in FIGS. 5 to 8 has the advantage that the power consumption can be suppressed low, and the drive unit 28 shown in FIG. Since the structure can effectively use the inverse piezoelectric effect, it is advantageous for generating large displacement.
In the present invention, the thickness of the electrodes 26a and 26b shown in FIG. 1 and the like may be set to an appropriate thickness according to the application. However, if the thickness is excessively large, the electrode acts as a relaxation layer and the bending displacement is small. The thickness is preferably 15 μm or less, more preferably 5 μm or less, because it is easy to be formed.
The material of the electrodes 26a and 26b is solid at room temperature, can withstand a high-temperature oxidizing atmosphere when the electrode and the substrate and / or the piezoelectric / electrostrictive layer are integrated by firing, and has excellent conductivity. It is preferable that it is made of the following material. Specifically, for example, aluminum, titanium, chromium, iron, cobalt, nickel, copper, zinc, niobium, molybdenum, ruthenium, palladium, rhodium, silver, tin, tantalum, tungsten, iridium, platinum, gold, lead or the like Metal or an alloy thereof.
In the present invention, the electrodes 26a and 26b preferably contain a trace amount of at least one of zirconium oxide, cerium oxide and titanium oxide in addition to these metals.
It is preferable that the material of the electrodes 26a and 26b is determined in consideration of the method of forming the piezoelectric / electrostrictive layer 27. For example, in the piezoelectric / electrostrictive film element 10 shown in FIGS. 1 and 2, when the piezoelectric / electrostrictive layer 27 is subjected to the heat treatment, the piezoelectric / electrostrictive layer 27 The lower electrode 26b provided in contact with is formed of a platinum group simple substance which does not change even at the heat treatment temperature of the piezoelectric / electrostrictive layer 27, an alloy of the platinum group simple substance with gold and / or silver, an alloy of the platinum group, Alternatively, a material composed of a high melting point metal such as an alloy of two or more metals of different platinum groups and gold and / or silver is preferable.
Also, in the piezoelectric / electrostrictive film type element 11 having the drive section 28 having a multilayer structure as shown in FIG. 10, the piezoelectric / electrostrictive layers 27a to 27d are already formed at the time of the heat treatment. The lower electrode 25e and the electrodes 25b to 25d provided between the piezoelectric / electrostrictive layers 27a to 27d are preferably made of the above-mentioned high melting point metal.
On the other hand, in the piezoelectric / electrostrictive film type element 10 shown in FIGS. 1 and 2, after the piezoelectric / electrostrictive layer 27 is subjected to the heat treatment, the upper electrode 26a formed on the piezoelectric / electrostrictive layer 27 or In the piezoelectric / electrostrictive film element 11 shown in FIG. 10, the uppermost electrode 25a formed after the piezoelectric / electrostrictive layers 27a to 27d are subjected to the heat treatment can be formed at a low temperature. Therefore, in addition to the above high melting point metal, it may be made of a low melting point metal such as aluminum, gold, silver and the like.
Examples of the method for forming the electrode include ion beam, sputtering, vacuum deposition, PVD, ion plating, CVD, plating, screen printing, spraying, dipping and the like.
In the present invention, the material of the piezoelectric / electrostrictive layer 27 shown in FIG. 1 and the like may be any material that causes an electric field-induced strain such as a piezoelectric or electrostrictive effect, and may be crystalline or amorphous. The material of the piezoelectric / electrostrictive layer 27 may be a semiconductor or a ceramic, and the ceramic may be either a ferroelectric ceramic or an antiferroelectric ceramic.
However, lead zirconate has a high electromechanical coupling coefficient and a high piezoelectric constant, has low reactivity with the ceramic substrate during sintering of the piezoelectric / electrostrictive film, and has a stable composition. , Lead titanate, Lead zirconate titanate, Lead magnesium niobate, Lead nickel niobate, Lead zinc niobate, Lead manganese niobate, Lead antimony stannate, Lead manganese tungstate, Lead cobalt niobate, Barium titanate, Ceramics containing at least one selected from the group consisting of sodium bismuth titanate, sodium potassium niobate, and strontium bismuth tantalate are preferable, and among them, a material mainly containing lead zirconate titanate and lead magnesium niobate Alternatively, a material containing sodium bismuth titanate as a main component is preferable.
In addition, lanthanum, calcium, strontium, molybdenum, tungsten, barium, niobium, zinc, nickel, manganese, cerium, cadmium, chromium, cobalt, antimony, iron, yttrium, tantalum, lithium, bismuth, and A material containing a trace component composed of at least one oxide selected from the group consisting of tin may be used. For example, there is a case where advantages such as the ability to adjust the anti-field electric field and the piezoelectric characteristics can be obtained by adding a minor component such as lanthanum or strontium to lead zirconate titanate and lead magnesium niobate as main components. .
In the present invention, the thickness of the piezoelectric / electrostrictive layer 27 shown in FIG. 1 and the like depends on the mechanical strength of the piezoelectric / electrostrictive film element 10 and the securing of a desired bending displacement. It is preferable that the thickness is approximately equal to the thickness of Specifically, the ratio of the thickness to the vibrating portion 20 (vibrating portion / piezoelectric / electrostrictive layer) is preferably 0.1 to 30, more preferably 0.3 to 10, and 0 to 10. It is particularly preferred that it is from 0.5 to 5.
If the thickness ratio of the vibrating section 20 to the vibrating section 20 (vibrating section / piezoelectric / electrostrictive layer) is within this range, a piezoelectric / electrostrictive material is applied onto the vibrating section 20 and then subjected to a heat treatment to obtain a piezoelectric material. When forming the / electrostrictive layer 27, the vibrating section 20 easily follows the firing shrinkage of the piezoelectric / electrostrictive layer 27, and the piezoelectric / electrostrictive layer 27 is dense and has high resistance to vibration without peeling. be able to.
The thickness of the piezoelectric / electrostrictive layer 27 may be 5 to 100 μm in order to make the piezoelectric / electrostrictive film element 10 compact, etc. Preferably, it is more preferably 5 to 50 μm, and particularly preferably 5 to 30 μm.
In the case of the piezoelectric / electrostrictive film element 11 shown in FIG. 10, since the aspect ratio can be increased by making each of the piezoelectric / electrostrictive layers 27a to 27d thin, / The thickness of the electrostrictive layers 27a to 27d is preferably 30 μm or less.
Further, it is preferable that the plurality of piezoelectric / electrostrictive layers 27a to 27d are formed so as to be gradually thinned in order from the lower layer. _n Is t _n ≤t _n-1 × 0.95 is preferably formed. The amount of strain of the piezoelectric / electrostrictive layer is larger as the thickness of the piezoelectric / electrostrictive layer is thinner at the same driving voltage. By making the strain larger than the layer, the bending efficiency can be increased, and the bending displacement can be more effectively expressed.
In the present invention, the piezoelectric / electrostrictive layer 27 of the piezoelectric / electrostrictive film element 10 shown in FIG. 1 and the like is made of, for example, a ceramic material corresponding to the material constituting the piezoelectric / electrostrictive layer 27 described above. Can be obtained by laminating the piezoelectric / electrostrictive material on the vibrating part 20 or the lower electrode 26b and then performing a heat treatment at a predetermined temperature. The piezoelectric / electrostrictive layer 27 of the piezoelectric / electrostrictive film element 11 shown in FIG. 10 is provided on the vibrating section 20 or on each of the electrodes 25b to 26e every time a piezoelectric / electrostrictive material is laminated, or on the vibrating section. It can be obtained by laminating the piezoelectric / electrostrictive material on the entire surface 20 or on each of the electrodes 25b to 26e and then performing a heat treatment at a predetermined temperature.
The piezoelectric / electrostrictive material can be prepared by, for example, an oxide mixing method, a coprecipitation method, or an alkoxide method.
As a method of applying the piezoelectric / electrostrictive material, various thick film forming methods such as a screen printing method, a dipping method, a coating method, and an electrophoresis method, or an ion beam method, a sputtering method, and a vacuum evaporation method , An ion plating method, a chemical vapor deposition method (CVD), or various thin film forming methods such as plating. Among them, a thick film forming method such as a screen printing method, a dipping method, a coating method, or an electrophoresis method is preferable in that a piezoelectric / electrostrictive layer 27 having good piezoelectric / electrostrictive characteristics can be obtained.
The heat treatment after the application of the piezoelectric / electrostrictive material may be performed at a temperature of 1000 to 1400 ° C. At the time of this heat treatment, an atmosphere control material having the same composition as the piezoelectric / electrostrictive material coexists in order to prevent volatilization of each component in the piezoelectric / electrostrictive material and obtain a ceramic having a desired composition. It is preferred to do so.
Next, the displacement transmitting section 30 in the present invention shown in FIG. 1 and the like is provided on the driving section 28 and is a member for leveling the vibration from the driving section 28 and transmitting it to the outside. In order to reduce the restraint, the drive portion 28 (particularly, a portion constituting the upper surface) is made of a material having a lower hardness than the material of the drive portion 28.
The displacement transmitting section 30 is preferably made of a material having a hardness as small as possible from the viewpoint of reducing the constraint on the driving section 28, and is preferably at least a material having a hardness smaller than that of the intermediate layer 29 described later. Specifically, for example, an epoxy-based, acrylic-based, silicone-based, or polyolefin-based organic resin-based material can be used.
In the present invention, the provision of the intermediate layer 29 described later basically ensures the followability of the displacement transmitting section 30 to the drive section 28. It can be made of a material having a smaller hardness.
In the present invention, in order to level the vibration from the drive unit 28 and transmit the vibration to the outside, the displacement transmission unit 30 includes a main drive part of the drive unit 28 (a part corresponding to the area where the electrodes are provided). This is preferably provided in a wider range.
As shown in FIG. 11, when the displacement transmitting portion 30 is formed of a relatively thin shape such as a film, the displacement transmitting portion 30 covers the entire outer surface of the driving portion 28. The displacement transmitting unit 30 may be provided so as to cover the entire outer surface of the driving unit 28 and part or all of the surface of the vibration unit 20 where the driving unit 28 is provided.
Further, as shown in FIG. 12, the displacement transmitting section 30 in the present invention is composed of a plurality of layers 30a and 30b made of the same material or two or more materials having different hardnesses. You may.
The method of providing the displacement transmitting section 30 includes, for example, a method of bonding a resin film with an adhesive; and a method of applying a solution, paste or slurry containing a material of the displacement transmitting member as a main component by a printing method or the like. Or a method of bonding a resin film by heating. Among them, a method in which the resin film is bonded by heating is preferable in that the operation is simple.
Next, the intermediate layer 73 in the present invention is provided between the drive unit 28 and the displacement transmitting unit 30. However, the intermediate layer 73 in the present invention is preferably made of a material having a hardness higher than that of the material forming the displacement transmitting unit 30 in order to increase the followability of the driving unit to vibrations. In order to enhance the followability of the drive unit to vibrations, the drive unit 28 is preferably made of a material having a lower hardness than the material forming the piezoelectric / electrostrictive layer 27 and a higher hardness than the material forming the displacement transmitting unit 30. .
In view of the above, the intermediate layer 29 according to the present invention has a Vickers depth of 1 to 5 times the Vickers depth of the material constituting the piezoelectric / electrostrictive layer. A material made of a certain material is preferable, and is made of a material that is larger than the Vickers depth of the material constituting the piezoelectric / electrostrictive layer and 5 times or less the same Vickers depth of the material constituting the piezoelectric / electrostrictive layer. Is more preferred.
For example, the material forming the displacement transmitting portion is an organic resin such as acrylic resin or polyethylene, and the material forming the piezoelectric / electrostrictive layer of the driving portion is made of lead zirconate titanate or lead magnesium niobate. In the case of such ceramics, the hardness of the intermediate layer in terms of Vickers depth is preferably from 0.3 to 1.4 μm, more preferably from 0.7 to 1.1 μm.
In the present invention, as a material constituting such an intermediate layer 29, the displacement transmitting section 30 can immediately respond to the vibration of the driving section 28, and the driving of the intermediate layer 29 can be performed by reducing the thickness of the intermediate layer 29. For example, a hybrid material having a matrix made of a polymer compound and inorganic particles is preferable in that the constraint on the portion 28 can be further reduced.
The matrix of the hybrid material includes, for example, vinyl polymers such as acrylic resins, addition polymers such as epoxy resins and polyurethanes, condensation polymers such as polyester and polycarbonate, and polymers of organosilicon compounds. And at least one high molecular compound selected from the group consisting of siloxane polymers. Above all, a siloxane polymer is preferred because the thickness of the intermediate layer 29 can be made very small to restrain the driving section and the heat resistance, water resistance, chemical resistance and water repellency are also excellent.
Herein, the term “siloxane polymer” as used herein refers to a polymer having a siloxane bond (—Si—O—) in the main chain, and part of the polymer has a methyl group, an ethyl group, or a propyl group. Alkyl groups such as an alkyl group, a phenyl group, an alkenyl group such as a vinyl group, or a β-methoxyethoxy group, an acetyl group, a γ-methacryloxypropyl group, a γ-glycidoxypropyl group, a γ-chloropropyl group, Includes those having various organic groups such as a substituted alkyl group such as a γ-mercaptopropyl group, a γ-aminopropyl group, a trifluoromethyl group, or a fluorine-substituted alkyl group.
In the present invention, among the above siloxane polymers having various organic groups, siloxane polymers having a fluorine-substituted alkyl group are the main components in view of heat resistance, water resistance, chemical resistance, water repellency and the like. Are preferred.
Further, as the siloxane polymer containing the fluorine-substituted alkyl group, a polymer having the structural units represented by the following formulas (1) to (3) is preferable.
[0077]
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[0078]
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[0079]
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In the above formulas (1) to (3), R ¹ Represents a fluoroalkyl group having 1 to 16 carbon atoms or a perfluoroalkyl group; ^Two Represents an alkyl group having 1 to 16 carbon atoms, a halogenated alkyl group, an aryl group, an alkylaryl group, an arylalkyl group, an alkenyl group, or an alkoxy group, a hydrogen atom or a halogen atom. A is an integer of 1 to 12, b is an integer of 0 to 24, c is an integer of 0 to 24, and b + c is 2a.
On the other hand, as the inorganic particles contained in the hybrid material, for example, Al _Two O _Three , B _Two O _Three , TiO _Two , ZrO _Two , SnO _Two , CeO _Two , P _Two O _Five , Sb _Two O _Three , Sb _Two O _Five , MoO _Three , ZnO, WO _Three , CaF _Two , NaF, NaAlF _Five , MgF, and SiO _Two At least one selected from the group consisting of _Two Is preferably used as the main component. _Two With the main component being Al _Two O _Three , B _Two O _Three , TiO _Two , ZrO _Two , SnO _Two , CeO _Two , P _Two O _Five , Sb _Two O _Three , Sb _Two O _Five , MoO _Three , ZnO, and WO _Three Those containing at least one member selected from the group consisting of Note that SiO _Two And the molar ratio of inorganic oxides other than silica (inorganic oxides other than silica / SiO 2 _Two ) Is preferably in the range of 0.0001 to 1.0.
Since the particle diameter of the inorganic particles affects the vibration transmission of the intermediate layer and the response of the displacement transmission section to vibration of the driving section, the average particle diameter is 5 nm to 5 nm from the viewpoint of optimizing these characteristics. Those having an average particle diameter of 1 μm are preferable, and those having an average particle diameter of 10 nm to 200 nm are more preferable.
The inorganic particles may have a bimodal particle size distribution. When an intermediate layer containing such inorganic particles is used, voids between the large-diameter inorganic particles can be filled with small-diameter inorganic particles to increase the volume fraction of the inorganic particles in the intermediate layer. The hardness of the layer can be made higher and the intermediate layer can be made even thinner.
The inorganic particles having a bimodal particle size distribution include a particle existing between two peaks in that voids between large inorganic particles can be effectively filled with small inorganic particles. The ratio (D / C) of the average particle size (C) of the large-sized inorganic particles larger than the particle size corresponding to the inflection point to the average particle size (D) of the small-sized inorganic particles smaller than the particle size at the inflection point ) Is preferably from 0.05 to 0.7, more preferably from 0.1 to 0.5. In addition, the inorganic particles having the bimodal particle size distribution have a ratio (F / E) of the mass (E) of the large-diameter inorganic particles and the mass (F) of the small-diameter inorganic particles in a similar manner. Those having 0.05 to 0.7 are preferable, and those having 0.1 to 0.5 are more preferable.
The hybrid material used in the present invention can be a combination of the above-mentioned matrix composed of various polymer compounds and the above-mentioned various inorganic particles. Among them, a matrix mainly composed of a polysiloxane polymer and a silica A hybrid material composed of inorganic particles mainly composed of: a matrix composed mainly of a polysiloxane polymer having a fluorine-substituted alkyl group; and a silica composed mainly of Al _Two O _Three , B _Two O _Three , TiO _Two , ZrO _Two , SnO _Two , CeO _Two , P _Two O _Five , Sb _Two O _Three , Sb _Two O _Five , MoO _Three , ZnO, and WO _Three Hybrid materials comprising inorganic particles containing at least one member selected from the group consisting of:
When the intermediate layer 29 is made of the hybrid material, the intermediate layer 29 is excellent in heat resistance, water resistance, chemical resistance, water repellency, etc., and also has excellent adhesion to the driving section and the displacement transmitting section, and is thin. Due to the layering, the constraint on the driving unit can be reduced.
In order to obtain a quick response to the drive section while suppressing the influence on the vibration transmission to the displacement transmission section, the thickness of the intermediate layer 29 in the present invention should be considered in addition to the above hardness. Is preferred. Specifically, the thickness of the intermediate layer 29 is preferably 0.1 to 10 μm, more preferably 0.1 to 5 μm, and particularly preferably 0.1 to 2 μm. When the thickness of the intermediate layer is within this range, the restraint on the drive unit 28 is small, and the responsiveness of the displacement transmission unit to the drive unit can be increased without substantially reducing the amount of bending displacement of the drive unit 28.
Further, from the same point, the thickness of the intermediate layer 29 is preferably not more than 1/15, more preferably not more than 1/20, of the total thickness of the vibrating section 20 and the driving section 28. More preferably, it is particularly preferably 1/30 or less.
As shown in FIG. 1, the intermediate layer 29 in the present invention may be provided at least on both opposing surfaces of the driving unit 28 and the displacement transmitting unit 30 so as to include mutually corresponding parts. However, in order to improve the heat resistance, water resistance, chemical resistance, water repellency, etc. of the piezoelectric / electrostrictive film element, an intermediate layer 29 may be further provided to cover the entire outer surface of the drive unit 28, As shown in FIG. 2, furthermore, providing the intermediate layer 29 to cover the entire outer surface of the driving unit 28 and the entire surface of the vibrating unit 20 where the driving unit is provided has heat resistance, water resistance, chemical resistance, and the like. In addition to being able to further improve the water repellency and the like, the manufacturing process of the piezoelectric / electrostrictive film type element is simplified, and it is possible to flexibly cope with variations in the shape and size of the driving unit 28 and the displacement transmitting unit 30. .
As shown in FIG. 2, when the intermediate layer 29 is provided on the opposing surfaces of the drive unit 28 and the displacement transmission unit 30 other than the mutually corresponding portions, the drive unit 28 and the displacement The thickness of the intermediate layer 29 existing on the opposing surfaces of the transmission portion 30 other than the mutually corresponding portions can be made thicker or thinner than the preferable thickness of the intermediate layer 29 described above.
As a method for forming the intermediate layer 29 in the present invention, for example, a coating liquid in which inorganic particles and a desired polymerizable oligomer are mixed in a dispersion liquid is applied to the piezoelectric / electrostrictive layer 27 and then dried. Methods can be mentioned. According to this method, in the drying step accompanying the formation of the intermediate layer 29, the contraction of the intermediate layer 29 is small, and the occurrence of cracks in the intermediate layer 29, the drive unit 28, and the like can be suppressed.
In the present invention, from the beginning, it is possible to use a coating solution in which the polymer compound constituting the matrix in the above-mentioned hybrid material is mixed in a dispersion, but it is possible to form a dense and uniform intermediate layer. In order to do so, it is preferable that a polymerizable oligomer corresponding to a desired polymer compound is mixed in a dispersion.
As the dispersion medium used in the coating liquid, for example, a polar dispersion medium such as water, methanol, ethanol, propanol, isopropyl alcohol, butanol, or acetone is preferable because a uniform dispersion can be easily obtained.
As the inorganic particles to be mixed in the dispersion medium, those having the above-mentioned components, particle diameters and particle size distributions may be used. The polymerizable oligomer used to form the matrix in the present invention includes a vinyl polymer such as an acrylic resin described above, an addition polymer such as an epoxy resin or a polyurethane, a condensation polymer such as a polyester or a polycarbonate, or an organic polymer. A polymerizable oligomer corresponding to a polysiloxane polymer which is a polymer of a silicon compound can be given.
As the polymerizable monomer or oligomer corresponding to the polysiloxane polymer having a fluorine-substituted alkyl group, a fluorine-containing silicone compound having a fluoroalkyl group represented by the following formula (4) or (5): Can be mentioned.
[0096]
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[0097]
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In the above formulas (4) and (5), R ¹ Represents a fluoroalkyl group having 1 to 16 (preferably 3 to 12) carbon atoms or a perfluoroalkyl group; ^Two ~ R ⁷ Is an alkyl group having 1 to 16 (preferably 1 to 4) carbon atoms, a halogenated alkyl group having 1 to 6 (preferably 1 to 4) carbon atoms, and an aryl group having 6 to 12 (preferably 6 to 10) carbon atoms An alkylaryl group having 7 to 14 (preferably 7 to 12) carbon atoms, an arylalkyl group, an alkenyl group having 2 to 8 (preferably 2 to 6) carbon atoms, 1 to 6 (preferably 1 to 3) Represents an alkoxy group, a hydrogen atom, or a halogen atom. A is an integer of 1 to 12, b is an integer of 0 to 24, c is an integer of 0 to 24, and b + c is 2a.
Specifically, heptadecafluorodecylmethyldimethoxysilane, heptadecafluorodecyltrichlorosilane, heptadecafluorodecyltrimethoxysilane, trifluoropropyltrimethoxysilane, tridecafluorooctyltrimethoxysilane, or methoxydisilane And the like.
The above polymerizable oligomer undergoes condensation polymerization by a dehydration or dealcoholization reaction in a drying step described later, and becomes a desired polymer compound constituting the matrix of the intermediate layer.
In the present invention, the mixing ratio of the polymerizable oligomer and the inorganic particles is preferably set in an appropriate range according to the type of each component. For example, when a polymerizable monomer corresponding to a polysiloxane polymer having a fluorine-substituted alkyl group is used as the polymerizable oligomer, the ratio of the inorganic particles is 0.1 to 300 parts by weight with respect to 100 parts by weight of the polymerizable oligomer. It is preferable to include it in the coating liquid so as to make it more preferable, and it is more preferable to include it in the coating liquid so as to be 1 to 100 parts by weight.
In the present invention, examples of a method of applying the coating solution to the piezoelectric / electrostrictive layer 27 include a coating method such as a dipping method, a spray method, and a spin coating method. The spin coating method is preferred because it can be easily thinned.
In order to provide a uniform intermediate layer 29, it is preferable to use a coating solution having a solution viscosity of 1000 cP or less, more preferably to a coating solution having a solution viscosity of 300 cP or less, and more preferably to a coating solution having a solution viscosity of 50 cP or less. It is particularly preferable to use a coating solution.
To provide the intermediate layer 29 with a thickness of 1/15 or less, more preferably 1/30 or less of the total thickness of the vibrating section 20 and the driving section 28, Immediately after the coating solution is dropped by the coating method, the rotation speed is preferably set to 1500 rpm or more. Even when the coating agent is applied to the entire piezoelectric / electrostrictive layer by the dipping method, the intermediate layer 29 having the above thickness can be provided by performing the step of blowing compressed air. From the viewpoint that a uniform layer can be formed, it is preferable to form by a spin coating method.
In the present invention, the intermediate layer 29 is formed by drying after the application of the coating solution, and it is preferable to select appropriate conditions for the drying according to the composition of the coating solution. For example, a polymerizable oligomer corresponding to a vinyl polymer such as an acrylic resin, an addition polymer such as an epoxy resin or a polyurethane, a polyester, or a condensation polymer such as a polycarbonate, which is a constituent material of the matrix, is mixed in the coating liquid. In this case, after applying the coating solution, the coating solution may be left at room temperature for drying.
On the other hand, if the polymerizable oligomer corresponding to the above-mentioned polysiloxane polymer as a constituent material of the matrix is mixed in the coating solution, the coating solution is left at room temperature for 10 minutes or more after coating. After removing most of the solvent, it is preferable to perform drying by heating while increasing the ambient temperature to a desired temperature at a rate of 600 ° C./hr or less.
If the coating solution is heated and dried immediately after coating, or if the temperature is rapidly raised and dried, the coating solution shrinks rapidly due to rapid evaporation of the solvent in the coating solution, and cracks occur in the intermediate layer. Or peeling may occur at the interface with the voltage / electrostrictive layer.
The drying by heating is preferably performed at 60 to 120 ° C., more preferably at 100 to 120 ° C. When dried at a temperature exceeding 120 ° C., the coating solution rapidly shrinks due to rapid evaporation of the solvent in the coating solution as in the case of leaving at room temperature, cracks are generated in the intermediate layer, and voltage / electrostriction occurs. Peeling may occur at the interface with the layer. On the other hand, if the drying is performed at a temperature lower than the heating temperature, the removal of water dissolved in the organic solvent and the organic solvent becomes insufficient.
When a coating solution in which a polymer oligomer corresponding to a polysiloxane polymer is mixed is applied, it is preferable to further perform a curing treatment by heating at a higher temperature continuously or in a separate step after the drying. Specifically, it is preferable to heat at a temperature of 700 ° C. or less, more preferably at a temperature of 600 ° C. or less, more preferably at a temperature of less than 500 ° C., and at a temperature of less than 450 ° C. It is particularly preferred to do so.
When the temperature of the curing treatment by the heating exceeds the above temperature range, components such as Si in the intermediate layer react with the material constituting the piezoelectric / electrostrictive layer, and the performance of the piezoelectric / electrostrictive layer is reduced. In some cases, the piezoelectric / electrostrictive layer causes a defect, resulting in dielectric breakdown, mechanical breakdown, or the like. In addition, decomposition of the organic component in the intermediate layer may occur, and cracks may occur in the intermediate layer.
In the present invention, the siloxane bond (—Si—O—) is adjusted by adjusting the composition ratio of the polymerizable oligomer and the inorganic particles in the coating solution, or by adjusting the heating temperature during the curing treatment. ), The mechanical properties such as hardness (hardness increases as the composition ratio of inorganic particles increases or as the temperature during the curing process increases), and water repellency, etc. Can be optimized for its chemical properties.
The piezoelectric / electrostrictive film type element of the present invention has been described above. The piezoelectric / electrostrictive film type element of the present invention is used as a display element or an optical switch by utilizing its displacement operation. be able to. Specifically, for example, as shown in FIG. 13, the displacement transmitting unit 30 (30a, 30b) is configured to include an optical path changing unit (not shown) and a light reflecting unit (not shown). The displacement transmitting section 30 (30a) is disposed at a position close to the optical waveguide plate 200. Then, by operating the drive unit 28 in accordance with the electric signal, the displacement transmission unit 30 (30a) having a light reflection function or the like is brought into contact with or separated from the optical waveguide plate, thereby performing a desired display or switching of an optical path. (In the figure, the light is indicated by 180). The specific contents are described in Japanese Patent Application Laid-Open No. 10-78549, which is hereby incorporated by reference. Further, in the present invention, in such an element, by providing a predetermined intermediate layer, the displacement transmitting section can be operated by accurately following the bending displacement of the driving section, so that a higher-speed response is possible. Become.
[0113]
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In addition, evaluation about each Example and the comparative example was performed as follows.
[0114]
(Evaluation method)
(1) Bending displacement
The amount of displacement when a 3 kV / mm electric field was applied to the piezoelectric / electrostrictive film type devices obtained in Examples and Comparative Examples at room temperature was measured with a laser Doppler vibrometer. Numerical values are shown as average values of numerical values obtained by a plurality of driving units.
[0115]
(2) Vickers depth
The indentation depth of the intermediate layer, the piezoelectric / electrostrictive layer, the electrode, and the base of the piezoelectric / electrostrictive film type devices obtained in the examples and comparative examples was measured using a microhardness indenter under the following conditions.
[0116]
(1) Equipment: Shimadzu Dynamic Ultra-Micro Hardness Tester DUH-201
{Circle around (2)} Indenter: Diamond indenter having a Vickers shape with a facing angle of 136 °
(3) Test mode: Load-unloading test (a test in which the load is increased at a constant speed, temporarily held, and then reduced at a constant speed)
(4) Indentation load: 1gf
(5) Pushing speed: 0.145 gf / sec
(6) Load holding time: 10 sec
{Circle around (7)} Others: When the test object (electrode, piezoelectric / electrostrictive layer, and base) is too small to fit the Vickers indenter under appropriate conditions because it has a curved surface or irregularities. Measures a Vickers indenter of the same material that can be pressed under appropriate conditions as a test object.
[0117]
(3) Average particle size and particle size distribution of inorganic particles
In a state where the inorganic particles used in the examples and comparative examples were dispersed in isopropanol, the dispersion was measured by a dynamic light scattering method using a dynamic light scattering photometer DSL7000 manufactured by Otsuka Electronics Co., Ltd.
[0118]
(Example 1)
First, Y _Two O _Three Stabilized ZrO _Two A substrate layer having a thickness of 150 μm and a size of 60 mm × 60 mm, having small through holes with a diameter of 100 μm at a pitch of 1.5 mm was prepared. Further, a 10 μm-thick spacer layer made of the same material and having a size of 60 mm × 60 mm and having 1.0 mm × 1.0 mm voids at a 1.5 mm pitch, and a 60 μm × 10 mm A thin plate layer having a thickness of 60 mm and a thickness of 10 μm was prepared. Next, the outer extensions were aligned, the substrate layer, the spacer layer, and the thin plate layer were laminated in this order and fired and integrated (the thin plate layer corresponds to the vibrating portion, and the spacer layer and the substrate layer correspond to the fixed portion).
Next, platinum lower electrodes (dimensions: 0.6.times.0.6 mm, thickness: 3.0 .mu.m) were respectively formed by screen printing at positions corresponding to the respective cavities of the spacer layer on the vibrating portion. It was formed and integrated with the vibrating part by heat treatment at 1300 ° C. for 2 hours. Next, a piezoelectric material mainly composed of three components of lead zirconate, lead titanate and lead magnesium niobate is laminated on the lower electrode in a range of 0.8 × 0.8 mm (a wider range including the lower electrode). After that, an atmosphere control material having the same composition as the piezoelectric material was heat-treated at 1275 ° C. for 2 hours while coexisting in the container to provide a piezoelectric layer having a thickness of 20 μm. Next, an upper electrode made of gold was formed on the piezoelectric layer by screen printing at a thickness of 0.2 μm in a range of 0.6 × 0.6 mm, and then heat-treated at 600 ° C. In the above steps, 30 × 30 (900 / substrate) driving units were provided on the vibrating unit at 1.5 mm intervals.
Next, the obtained product was fixed on a sample stage, and a mixture of 30% by mass of colloidal silica (solid content concentration: 20% by mass) in which amorphous silica particles were dispersed in isopropyl alcohol, and isopropyl alcohol and water. A coating liquid (trade name: Ceramate C-) in which a dispersion medium is mixed with 70% by mass of a polymerizable oligomer solution in which an equimolar mixture of tetraethoxysilane and methylethoxysilane is contained in an amount of 20% by mass based on the total amount of the polymerizable oligomer solution. 513, manufactured by Catalyst Chemical Industry Co., Ltd., viscosity (25 ° C.): 20 cP or less, pH (25 ° C.): 3 to 5, liquid specific gravity: 0.9 to 1.0 g / ml) Was coated on the entire outer surface by spin coating. At this time, the sample stage first rotated at 500 rpm. Immediately after the application liquid was dropped, the rotation speed was increased to 2000 rpm, held for 30 seconds, and then stopped.
After the rotation was stopped, the coated product was left at room temperature for 30 minutes, and then heated at a heating rate of 200 ° C./h to maintain the temperature between 80 and 120 ° C. for 1 hour. Then, the temperature was continuously raised to 300 ° C., and a curing treatment was performed at the same temperature for 1 hour to form an intermediate layer having a thickness of about 0.5 μm.
Finally, a coating solution containing a modified epoxy oligomer as a main component is applied on the intermediate layer by a screen printing method, and then cured at 130 ° C. for 1 hour to form a displacement transmitting portion. A strain film type device was manufactured.
The Vickers indenter pressing depth of each component of the obtained piezoelectric / electrostrictive film element was 0.18 μm for the vibrating part, 0.27 μm for the piezoelectric / electrostrictive layer, and 0.87 μm for the intermediate layer. there were. The thickness of the intermediate layer was 0.5 μm.
[0124]
(Comparative Example 1)
A piezoelectric / electrostrictive film was formed in the same manner as in Example 1, except that a displacement transmitting portion was formed on the driving portion without applying an intermediate layer by applying a coating solution obtained by mixing colloidal silica and a polymerizable oligomer solution. A mold device was manufactured.
[0125]
(Evaluation)
As shown in FIG. 14, in the piezoelectric / electrostrictive film type element of Comparative Example 1 in which the predetermined intermediate layer was not provided, although the average of the initial bending displacement of each driving unit was about 2.0 μm, After several hundred million times, the average of the bending displacement decreases to about 80% of the average of the initial bending displacement, and further decreases as the number of pulses increases. The average of the amount decreased to about 70% of the average of the initial bending displacement.
On the other hand, in the piezoelectric / electrostrictive film type device of Example 1 provided with the intermediate layer, the average amount of initial bending displacement was about 1.9 μm, which was about 1.9 μm. It is almost the same as above. Even if the number of pulses increases, there is almost no change in the bending displacement. Even if the number of pulses is 2 billion times, the average of the bending displacement is maintained at 98% of the average of the initial bending displacement. It had been.
[0127]
As described above, according to the present invention, it is possible to suppress the initial bending displacement of the drive unit due to the provision of the displacement transmitting unit, and to reduce the initial bending displacement even after long-term continuous use. Thus, it is possible to provide a piezoelectric / electrostrictive film-type element which is hardly reduced in the amount of bending displacement and has excellent durability.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view showing one embodiment of the present invention.
FIG. 2 is a partial cross-sectional view showing another embodiment of the present invention.
FIG. 3 is a partial cross-sectional view showing a part of a fixed part, a vibrating part, and a driving part according to still another embodiment of the present invention.
FIG. 4 is a partial cross-sectional view showing a part of a fixed part, a vibrating part, and a driving part according to still another embodiment of the present invention.
FIG. 5 is a partial cross-sectional view showing a part of a fixed part, a vibrating part, and a driving part according to still another embodiment of the present invention.
FIG. 6 is a partial top view of FIG. 5;
FIG. 7 is a partial cross-sectional view showing a part of a fixed part, a vibrating part, and a driving part according to still another embodiment of the present invention.
FIG. 8 is a partial cross-sectional view showing a part of a fixed part, a vibrating part, and a driving part according to still another embodiment of the present invention.
FIG. 9 is a partial cross-sectional view showing a part of a fixed part, a vibrating part, and a driving part according to still another embodiment of the present invention.
FIG. 10 is a partial cross-sectional view showing a part of a fixed part, a vibrating part, and a driving part according to still another embodiment of the present invention.
FIG. 11 is a partial sectional view showing still another embodiment of the present invention.
FIG. 12 is a partial sectional view showing still another embodiment of the present invention.
FIG. 13 is a partial cross-sectional view schematically showing one example of a display element to which the piezoelectric / electrostrictive film type element of the present invention is applied.
FIG. 14 is a graph showing the rate of change in bending displacement with respect to the number of pulses for the piezoelectric / electrostrictive film type devices of the example of the present invention and the comparative example.
[Explanation of symbols]
10: piezoelectric / electrostrictive film element, 11: piezoelectric / electrostrictive film element, 12A: substrate layer, 12B: spacer layer, 12C: thin plate layer, 14: void, 18, 44: through hole, 20: vibration Part, 22: fixed part, 25 (25a to 25d): electrode, 26 (26a to 26f): electrode, 27 (27a to 27d): piezoelectric / electrostrictive layer, 28: drive part, 29: intermediate layer, 30 ( 30a, 30b): Displacement transmitting section, 180: light, 200: optical waveguide plate.

Claims (8)

A vibrating part made of a ceramic thin plate, a fixed part made of ceramics supporting the vibrating part, a piezoelectric / electrostrictive layer, and at least one pair of electrodes provided in contact with the piezoelectric / electrostrictive layer; Piezoelectric / electrostrictive film type element comprising: a drive unit provided on the drive unit; and a displacement transmission unit provided on the drive unit and made of a material having a lower hardness than the material constituting the piezoelectric / electrostrictive layer of the drive unit. And
A piezoelectric / electrostrictive film element, wherein an intermediate layer is provided between the driving unit and the displacement transmitting unit. 2. The piezoelectric / electrostrictive film element according to claim 1, wherein the intermediate layer is made of a material having a lower hardness than a material forming the piezoelectric / electrostrictive layer and a hardness higher than a material forming the displacement transmitting section. The micro Vickers indenter indentation depth of the material constituting the intermediate layer (the indenter indentation depth when the macro Vickers load is 1 gf and the indentation speed is 0.145 gf / sec with a diamond indenter having a facing angle of 136 °) is as described above. 2. The piezoelectric / electrostrictive film type device according to claim 1, wherein the depth of the material forming the piezoelectric / electrostrictive layer is 1 to 5 times the indentation depth of the micro-Vickers indenter. 3. The piezoelectric / electrostrictive film element according to any one of claims 1 to 3, wherein the intermediate layer is formed of a hybrid material in which silica particles are dispersed in a matrix containing a polysiloxane polymer as a main component. . The piezoelectric / electrostrictive film element according to claim 1, wherein the thickness of the intermediate layer is 0.1 to 5 μm. The piezoelectric / electrostrictive film element according to claim 1, wherein at least one of the electrodes is provided in contact with the vibrating portion and the piezoelectric / electrostrictive layer. The electrode provided in contact with the vibrating portion and the piezoelectric / electrostrictive layer may be a platinum group simple substance, an alloy of a platinum group simple substance with gold and / or silver, an alloy of platinum group, or two different types of platinum group. The piezoelectric / electrostrictive film element according to any one of claims 1 to 6, comprising an alloy of the above metals, gold and / or silver. The piezoelectric / electrode according to any one of claims 1 to 7, wherein the driving unit is directly bonded to the vibrating unit and integrated with the base by heat-treating at least the piezoelectric / electrostrictive layer. Strain film type element.

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