JP3957054B2 - Droplet ejection head, ink cartridge, ink jet recording apparatus, microactuator, micropump, optical device, image forming apparatus, apparatus for ejecting droplets - Google Patents

Description

【００４１】
なお、（１）式において、Ｆ：電極間に働く力、ε：誘電率、Ｓ：電極の対向する面の面積、ｄ：電極間距離、 Ｖ：印加電圧である。
【００４２】
また、電極(構造体)自体は曲がらないため、電極（構造体）の付け根部（振動板に固定された固定端）の電極間隔を広く形成することにより、振動板の変形可能領域を拡大することができて、振動板を効率良く変位させることができるようになる。
【００４３】
したがって、電極間距離（電極間隔）を振動板側（電極の固定端部側）で広く、振動板と離れた側（電極の自由端部側）で狭くなる構成とすることで、振動板を効率良く大きく変位させることができる。
【００４４】
そして、振動板を更に効率良く大きく変位させるためは、前述のように構造体（電極）の高さＬを大きくすることが好ましい。この場合、構造体を形成するために、非常に厚い膜の堆積を要することなると、プロセスコストの増加を招いてしまったり、狭い電極間隔をエッチングなどで形成することが困難になったりする。また、堆積膜が薄いと、構造体の機械的強度が弱くなってしまい振動板を効率良く変位させることができなかったり、構造体自体の破壊などにより歩留まりが低下することがある。
【００４５】
そこで、本実施形態のヘッドでは、電極間隔を複数段階、特に３段階以上に異ならせて、電極間隔が、固定端部側で広く、自由端部側で狭くなっている構成として、電極の機械的強度を保ちつつ、膜の堆積の厚さを非常に厚くすることなく、電極を形成できるようにして、プロセスコストの増加を抑制しつつ構造体の高さＬを大きくし、振動板を更に効率良く大きく変位させることができるようにしている。
【００４６】
次に、上記第１実施形態に係るインクジェットヘッドの製造工程の一例について図７を参照して説明する。
同図（ａ）に示すように、面方位（１１０）、厚さ４００μｍのシリコン基板３１にＬＰ−ＣＶＤにより振動板１０となるシリコン窒化膜３２を０．３μｍ厚みに形成し、プラズマＣＶＤによりシリコン酸化膜３３ａを２μｍ厚みに形成し、既知のリソグラフィー、ドライエッチング技術によりシリコン酸化膜３３ａをパターニングすることにより、線幅１０μｍ、間隔は２μｍのシリコン酸化膜３３ａを形成する。ここで、シリコン窒化膜３２はシリコン酸化膜３３ａのエッチングの際のエッチングストッパーとして機能する。なお、シリコン酸化膜は低温熱ＣＶＤや高温ＣＶＤによって形成しても良い。
【００４７】
次に、同図（ｂ）に示すように、シリコン酸化膜３３ａ上にシリコン酸化膜３３ｂを２μｍ厚みに形成し、同様に、既知のリソグラフィー、ドライエッチング技術によりシリコン酸化膜３３ｂをパターニングすることにより、線幅８μｍ、間隔は４μｍのシリコン酸化膜３３ｂを形成した。
【００４８】
その後、同図（ｃ）に示すように、表面に電極１４を形成するためのポリシリコン膜３４をＣＶＤ法により３μｍ厚みに堆積する。シリコン酸化膜３３ｂの間隔を埋め込み基板の平坦化が得られるのに要するポリシリコン膜の厚さは２μｍ以上である。つまり、ここでは、埋め込み必要条件を満たし、基板もほぼ平坦化される。ここで、電極となるポリシリコン膜３４の高さＬは振動板１０となるシリコン窒化膜３２表面から約７μｍになるが、二段階のシリコン酸化膜３３ａ、３３ｂを形成しているので、ポリシリコン膜３４を堆積する厚さはシリコン酸化膜３３ａ一層の場合よりも薄くなるため、プロセスコストが低減される。
【００４９】
そして、図示しないが、上記の工程でシリコン基板３１の裏面側にも形成されるシリコン窒化膜３２、シリコン酸化膜３３ａ、３３ｂ、ポリシリコン膜３４は、研磨（ラッピングやグラインダーを用いた研磨工程を含むのが好適である。）により全て除去する。この際、表面のポリシリコン膜３４表面を保護膜（保護テープ）などで保護することが好ましい。また、研磨に限らずエッチング液などにより除去しても構わない。
【００５０】
次いで、同図（ｄ）に示すように、シリコン酸化膜３３ｂ上のポリシリコン膜３４にリソグラフィー、ドライエッチング技術により幅０．５μｍの溝３５を形成する。この場合、シリコン酸化膜３３ｂがエッチングストッパーとして機能する。
【００５１】
その後、同図（ｅ）に示すように、シリコン酸化膜３３ａ及び３３ｂをフッ酸水溶液などでエッチング除去することにより、電極間距離が３段階（ｄ１、ｄ２、ｄ３）に異なり、振動板側（固定端部側）で広い電極間距離ｄ１、振動板と離れた側（自由端部側）で狭い電極間距離ｄ３となる構造体からなる、ポリシリコン膜３４からなる電極１４が形成される。
【００５２】
この電極１４は段階的（３段階）に幅（ここでは振動板短手方向の幅）が広くなっていくので、２段階に幅が異なる電極よりも機械的強度が大きくなり、振動板を効率良く変位させることができ、歩留まりの向上が図れる。なお、ここでは、電極間距離を３段階に異なる構造としたが、４段階以上に異なる構造とすることもできる。
【００５３】
その後、同図（ｆ）に示すように、ＬＰ−ＣＶＤで水酸化カリウムエッチングのマスクとなるシリコン窒化膜を形成し、水酸化カリウム水溶液によりシリコン基板３１をエッチングし、吐出室６と同時にシリコン窒化膜３４からなる振動板１０を形成する。
【００５４】
なお、ここで、シリコン窒化膜３４からなる振動板１０はエッチングストッパーとして機能し、また、絶縁膜でもあるため電極１４と電気的に分離されていることとなる。シリコン窒化膜は引っ張り応力であるため振動板が座屈することはないが、引っ張り応力によって振動板１０を変形させることができないことがある。そのような場合には、シリコン窒化膜にボロン、リン、水素などの不純物をドープして応力緩和することができる。
【００５５】
また、電極をポリシリコンから形成することで、電極間隔をドライエッチングにより比較的高精度に形成できる。ただし、ノンドープのポリシリコンは高周波数駆動、多チャンネル駆動を行うと電極の電気抵抗値が問題となることがある。この場合には、n型又はp型の伝導型を有する不純物原子、例えばn型であればリン、砒素、p型であればボロンやアンチモン等を導入することにより電気抵抗値を低減することが好ましい。
【００５６】
次に、第２実施形態に係るインクジェットヘッドについて図８及び図９を参照して説明する。なお、図８は同ヘッドの製造工程における図７（ｄ）の平面図に相当する説明図、図９は同ヘッドの製造工程における図８のＡ−Ａ線に沿う断面説明図である。
【００５７】
この実施形態は、電極１４に開口部３６を形成するようにしたものである。すなわち、図７（ａ）〜（ｃ）と同様の製造工程を経た後、図８及び図９（ａ）に示すように、シリコン酸化膜３３ｂ上のポリシリコン膜３４にリソグラフィー、ドライエッチング技術により幅０．５μｍの溝を形成するとともに幅１．５μｍ、長さ数μｍの開口部３６を複数形成する。なお、開口部３６は電極間溝３５と連続的に形成しても、独立して形成しても良い。
【００５８】
その後、図９（ｂ）に示すように、シリコン酸化膜３３ａ、３３ｂを除去することにより、開口部３６有する電極１４が形成される。
【００５９】
このように電極１４に開口部３６を設けることにより、シリコン酸化膜が露出する面積を大きくすることができ、犠牲層であるシリコン酸化膜３３ａ、３３ｂを容易にエッチング除去することが可能となる。
【００６０】
次に、第３実施形態に係るインクジェットヘッドについてその製造工程と共に図１０及び図１１を参照して説明する。
先ず、図１０（ａ）に示すように、面方位（１１０）、厚さ４００μｍのシリコン基板４１に熱酸化膜４２を０．２μｍ厚みに形成し、続いて、ＬＰ−ＣＶＤによりシリコン窒化膜４３を０．３μｍ厚みで形成する。そして、プラズマＣＶＤによりシリコン酸化膜４４ａを２μｍ厚みに形成し、既知のリソグラフィー、ドライエッチング技術によりシリコン酸化膜４４ａをパターニングすることにより線幅１０μｍ、間隔が２μｍのシリコン酸化膜シリコン酸化膜４４ａを形成した。ここで、シリコン窒化膜４３はシリコン酸化膜４４ａのエッチングの際のエッチングストッパーとして機能する。
【００６１】
更に、シリコン酸化膜４４ａ上にシリコン酸化膜４４ｂを２μｍ厚みに形成し、既知のリソグラフィー、ドライエッチング技術によりシリコン酸化膜４４ｂをパターニングすることにより線幅８μｍ、間隔は４μｍのシリコン酸化膜４４ｂを形成した。なお、シリコン酸化膜は低温熱ＣＶＤや高温ＣＶＤにより形成しても良い。続いて、シリコン酸化膜４４ｂの表面にポリシリコン膜４５ａをＣＶＤ法により３μｍ厚みに堆積する。
【００６２】
その後、同図（ｂ）に示すように、シリコン酸化膜４４ｂ上のポリシリコン膜４５ａにリソグラフィー、ドライエッチング技術により幅１．５μｍの溝４６を形成する。ここで、溝４６の溝幅が比較的広くアスペクトが高くないため、容易に制御性良く溝を形成することができる。
【００６３】
そして、同図（ｃ）に示すように、全面にＣＶＤ法によりシリコン酸化膜を０．２μｍの厚さに形成する。なお、シリコン酸化膜は低温熱ＣＶＤや高温ＣＶＤ、プラズマＣＶＤにより形成しても良いが、非常にコンフォーマルに形成可能な低温熱ＣＶＤによるＯ_３−ＴＥＯＳ膜が好ましい。このシリコン酸化膜のエッチバックによりポリシリコン膜４５の側壁にシリコン酸化膜４７ａ及び４７ｂを形成する。
【００６４】
次いで、同図（ｄ）に示すように、表面にポリシリコン膜４５ｂを堆積した後、ポリシリコン膜４５ｂの表面にレジストを形成し、シリコン酸化膜４７ａ上のレジストを残し、シリコン酸化膜４７ｂ上のレジストを開口するようにレジスト４８をパターニングする。
【００６５】
その後、図１１（ａ）に示すように、ポリシリコン膜４５ｂをシリコン酸化膜４７ｂが露出するまでエッチングし、ポリシリコン膜４５ｂをパターニングする。その後レジスト４８を除去する。
【００６６】
次いで、同図（ｂ）に示すように、シリコン酸化膜４７ｂ及びシリコン酸化膜４４ａ、４４ｂをフッ酸水溶液などでエッチング除去することにより電極１４が形成される。
【００６７】
ここで、シリコン酸化膜４７ｂは犠牲層であり、電極間隔は犠牲層のエッチングにより形成されたこととなる。つまり、電極間隔が犠牲層の厚さにより規定された構成であるため、エッチング加工が困難な高アスペクトの溝形成でも高精度に形成することができる。なお、シリコン酸化膜４７ａはここで残っても、また、除去されてしまってもかまわない。
【００６８】
その後、同図（ｃ）に示すように、パターニングされたレジストをマスクとし、シリコン基板４１を高密度プラズマを用いたドライエッチング法によりエッチングすることにより、吐出室６と同時にシリコン酸化膜４２及びシリコン窒化膜４３からなる振動板１０を形成する。なお、ここで、シリコン酸化膜４２はエッチングストッパーとして機能する。また、シリコン酸化膜４２は、エッチング後除去しても良い。
【００６９】
なお、ポリシリコン膜４５ｂのパターニングについては一例にすぎず、別の例を図１２に示しているが、これらに限られるものではない。
【００７０】
次に、第４実施形態に係るインクジェットヘッドについてその製造工程と共に図１３を参照して説明する。
同図（ａ）に示すように、面方位（１１０）、厚さ４００μｍのシリコン基板５１にＬＰ−ＣＶＤにより振動板１０となるシリコン窒化膜５２を０．３μｍ厚みに形成し、プラズマＣＶＤによりシリコン酸化膜５３ａを２μｍ厚みに形成し、既知のリソグラフィー、ドライエッチング技術によりシリコン酸化膜５３ａをパターニングすることにより線幅１４μｍ、間隔は２μｍのシリコン酸化膜５３ａを形成する。ここで、シリコン窒化膜５２はシリコン酸化膜５３ａのエッチングの際のエッチングストッパーとして機能する。なお、シリコン酸化膜は低温熱ＣＶＤや高温ＣＶＤにより形成しても良い。更に、シリコン酸化膜５３ｂを厚さ３μｍで形成し、既知のリソグラフィー、ドライエッチング技術によりシリコン酸化膜５３ｂをパターニングすることにより線幅６μｍ、間隔は８μｍのシリコン酸化膜５３ｂを形成する。
【００７１】
その後、同図（ｂ）に示すように、表面にポリシリコン膜５４をＣＶＤ法により３μｍ厚みに堆積する。シリコン酸化膜５３ｂの間隔を埋め込み基板の平坦化が得られるのに要するポリシリコン膜５４の厚さは４μｍ以上である。したがって、ここでは、ポリシリコン膜５４に凹部５５ができる。
【００７２】
そして、シリコン酸化膜５３ｂ上のポリシリコン膜５４にリソグラフィー、ドライエッチング技術により幅０．５μｍの溝５６を形成する。ここで、シリコン酸化膜５３ｂがエッチングストッパーとして機能する。
【００７３】
その後、同図（ｃ）に示すように、シリコン酸化膜５３ａ及び５３ｂをフッ酸水溶液などでエッチング除去することにより、電極間距離ｄが３段階（ｄ１、ｄ２、ｄ３）に異なり、振動板側での電極間距離ｄ１が広く、振動板と離れた側での電極間距離ｄ３が狭くなっている構造体からなる電極１４が形成される。なお、ここでは、電極間距離が３段階に異なる構造としたが、４段階以上であっても良い。
【００７４】
次いで、同図（ｄ）に示すように、電極１４の表面に絶縁膜５７を成膜する。すなわち、駆動電圧を低くする（大きな静電気力を得る）ためには、電極１４の間隔を小さくしなければならないが、そのような微小な間隔を作製した場合、小さなダストであってもが電極上に載るとショートの原因となり、動作不良を起こすことになる。また、非常に微小な間隔なので、空気の湿度によって電極１４表面に微小な水滴が発生した場合にも、ショートの原因となる。そこで、電極１４の表面に絶縁膜５７を設けることにより、電極間のショートによる動作不良を低減することができる。
【００７５】
また、電圧を印加した時の電極間の放電により動作不良を起こすことがある。絶縁膜５７を設けることによって、耐圧も向上することができ信頼性の高い液滴吐出ヘッドが得られる。
【００７６】
この場合、絶縁膜５７を絶縁性に優れたシリコン酸化膜にすることにより、高耐圧で信頼性の高い電極を形成することができ、また、一般に半導体プロセスで使用されるように技術的に確立された形成方法が多種に渡り在るため制御性良く形成が可能である。
【００７７】
ここでは絶縁膜５７であるシリコン酸化膜をＣＶＤ法により形成している。ＣＶＤ法で形成することにより比較的均一に形成することができる。ただし、振動板１０上にも形成されてしまうため、振動板１０の剛性を上げてしまい振動板自体が変位しにくくなるというデメリットがあるが、誘電率が比較的大きく、実効ギャップを効率良く減少できる。
【００７８】
すなわち、図１４に示すように、高温ＣＶＤによるシリコン酸化膜を成膜した場合、シリコン酸化膜は被成膜表面に堆積して成膜されるので、成膜する前の電極面と成膜後の電極面は変化しない。したがって、シリコン酸化膜を厚さｔだけ成膜した場合、成膜前後の電極間隔Ｇ１は変化せず、空間間隔は膜厚分だけ狭くなったＧ２となる。
【００７９】
ここで、堆積絶縁膜（酸化膜）５７を形成する前の電気的な電極間間隔である実効ギャップＧは、Ｇ＝Ｇ１である。厚さｔの酸化膜５７形成した場合の実効ギャップＧ’は、酸化膜の誘電率をε1とすると、次の（２）式で表される。
【００８０】
【数２】

【００８１】
高温ＣＶＤによるシリコン酸化膜の誘電率ε1は４．０〜４．５であるので、Ｇ’＜Ｇ、となり、酸化膜（堆積絶縁膜）を形成することによって、実効ギャップを小さくすることができる。ここで用いた酸化膜の誘電率は４．０であった。Ｇ１を０．５μｍ、ｔを０．２μｍとすると、Ｇ’は０．２μｍとなり実効ギャップを２／５に小さくできる。前述した（１）式より電極間に働く静電力に換算すると６倍となり、同じ静電力を得ようとした場合、電圧は２／５に低電圧化できる。
【００８２】
すなわち、Ｇ１＝０．５μｍ（ε=４．０）のとき
ｔ＝０．２μｍの場合：Ｇ２＝０．１μｍ、Ｇ’＝０．２μｍ
となる。
【００８３】
誘電率が高いほど実効ギャップを小さくする効果は大きく、その他、ＰＥ−ＣＶＤのシリコン酸化膜などさらに大きな誘電率の膜を使うことによって実効ギャップを小さくする効果が大きくなる。
【００８４】
また、図１５に示すように、シリコン酸化膜を熱酸化膜５８とすることもできる。この熱酸化膜５８は、耐酸化膜であるシリコン窒化膜５２からなる振動板１０上には形成されず、また、狭い間隔を有する構造体でも膜形成における均一性に優れる。ただし、熱酸化膜５８は約４４％のシリコンを消費しながら成長するため、実効ギャップ減少の効率は上述した堆積膜による場合よりも低下する。
【００８５】
すなわち、図１６に示すように、熱酸化膜５８を成膜する前（酸化前）の電極１４は点線Ａで示す状態にあり、ギャップＧ１の間隔を隔てて設けられている。これに厚さｔの熱酸化膜５８を形成すると、約０．４４ｔの厚さのシリコンが消費され、電極１４の間隔はＧ３、空間間隔はＧ２となる。
【００８６】
熱酸化膜５８を形成する前の電気的な電極間間隔である実効ギャップＧは、Ｇ＝Ｇ１であり、厚さｔの熱酸化膜５８を形成した場合の実効ギャップＧ’は、熱酸化膜の誘電率をεとすると、次の（３）式で表される。
【００８７】
【数３】

【００８８】
ここで、熱酸化膜の誘電率εは３．７〜３．９であるので、Ｇ’＜Ｇ、となり、熱酸化膜を形成することによって、実効ギャップを小さくすることができるが、シリコンを消費するため、実効ギャップを小さく効率は低下することになる。
【００８９】
具体的に、熱酸化膜５８の誘電率を３．８として、Ｇ１を０．５μｍ、絶縁膜厚さｔを０．４μｍとすると、実行ギャップＧ’は０．２６μｍとなり、実効ギャップを約１／２に小さくできる。前述した（１）式より、電極間に働く静電力に換算すると３．７倍となり、同じ静電力を得ようとした場合、電圧は約１／２に低電圧化することができる。
【００９０】
すなわち、Ｇ１＝０．５μｍ（ε＝３．８）のとき
ｔ＝０．２μｍの場合：Ｇ２＝０．２８μｍ、Ｇ’＝０．３８μｍ
ｔ＝０．４μｍの場合：Ｇ２＝０．０６μｍ、Ｇ’＝０．２６μｍ
となる。
【００９１】
なお、電極表面に絶縁膜を形成して実効ギャップをより効率良く減少させるには、誘電率が大きな膜を用いることが効果的である。シリコン窒化膜はシリコン酸化膜に若干絶縁耐圧は劣るが、誘電率εが4〜７とシリコン酸化膜より大きいため実効ギャップをより効率良く減少させるのに適している。また、シリコン酸化膜でも熱窒化させたり、窒素プラズマなどを用いて誘電率の大きいＳｉＯＮ（オキシナイトライド）を形成することにより実効ギャップを減少させることができる。
【００９２】
次に、第５実施形態に係るインクジェットヘッドについて図１７を参照して説明する。なお、同図は同ヘッドの電極部分の要部拡大説明図である。
このヘッドでは、電極１４の表面に導電性の膜５９を形成している。導電性の膜５９を電極表面に成膜することによって、成膜前に電極間隔がＧ１であったのに対し、厚さｔの成膜後電極間隔は成膜厚さの２倍だけ小さいＧ２となる。
【００９３】
このように電極間隔を導電性膜の成膜により小さくすることができるので、静電力の向上、駆動電圧の低電圧化が可能となる。また、上述した電極表面に絶縁膜を形成する方法と併用して、信頼性の向上、更なる低電圧化を図ることもできる。
【００９４】
なお、成膜する金属膜としてはポリシリコン、あるいはスパッタや真空蒸着によるアルミニウム、ニッケル、タングステンなどの金属膜を用いることができる。均一性などを考慮した場合、ＣＶＤ法や選択ＣＶＤ法によりタングステン膜を形成するのが好ましい。また、金属膜は電極１４において電極間部に必ずしも形成されるものに限ったものではない。電極がポリシリコンからなる場合、電極が金属膜を含む構成とすることにより電気抵抗値を低減でき、高周波数駆動、多チャンネル駆動が容易になる。
【００９５】
次に、本発明に係るインクカートリッジについて図１８を参照して説明する。このインクカートリッジ１００は、ノズル孔１０１等を有する上記各実施形態のいずれかのインクジェットヘッド１０１と、このインクジェットヘッド１０１に対してインクを供給するインクタンク１０２とを一体化したものである。
【００９６】
このようにインクタンク一体型のヘッドの場合、ヘッドの低コスト化、信頼性は、ただちにインクカートリッジ全体の低コスト化、信頼性につながるので、上述したように低コスト化、高信頼性化、製造不良低減することで、インクカートリッジの歩留まり、信頼性が向上し、ヘッド一体型インクカートリッジの低コスト化を図れる。
【００９７】
次に、本発明に係るインクジェットヘッド又はインクカートリッジを搭載した、本発明に係る液滴を吐出する装置を含む画像形成装置としてのインクジェット記録装置の一例について図１９及び図２０を参照して説明する。なお、図１９は同記録装置の斜視説明図、図２０は同記録装置の機構部の側面説明図である。
【００９８】
このインクジェット記録装置は、記録装置本体１１１の内部に主走査方向に移動可能なキャリッジ、キャリッジに搭載した本発明に係るインクジェットヘッドからなる記録ヘッド、記録ヘッドへインクを供給するインクカートリッジ等で構成される印字機構部１１２等を収納し、装置本体１１１の下方部には前方側から多数枚の用紙１１３を積載可能な給紙カセット（或いは給紙トレイでもよい。）１１４を抜き差し自在に装着することができ、また、用紙１１３を手差しで給紙するための手差しトレイ１１５を開倒することができ、給紙カセット１１４或いは手差しトレイ１１５から給送される用紙１１３を取り込み、印字機構部１１２によって所要の画像を記録した後、後面側に装着された排紙トレイ１１６に排紙する。
【００９９】
印字機構部１１２は、図示しない左右の側板に横架したガイド部材である主ガイドロッド１２１と従ガイドロッド１２２とでキャリッジ１２３を主走査方向（図２０で紙面垂直方向）に摺動自在に保持し、このキャリッジ１２３にはイエロー（Ｙ）、シアン（Ｃ）、マゼンタ（Ｍ）、ブラック（Ｂｋ）の各色のインク滴を吐出する本発明に係る液滴吐出ヘッドであるインクジェットヘッドからなるヘッド１２４を複数のインク吐出口を主走査方向と交叉する方向に配列し、インク滴吐出方向を下方に向けて装着している。またキャリッジ１２３にはヘッド１２４に各色のインクを供給するための各インクカートリッジ１２５を交換可能に装着している。なお、本発明に係るヘッド一体型のインクカートリッジを搭載するようにすることもできる。
【０１００】
インクカートリッジ１２５は上方に大気と連通する大気口、下方にはインクジェットヘッドへインクを供給する供給口を、内部にはインクが充填された多孔質体を有しており、多孔質体の毛管力によりインクジェットヘッドへ供給されるインクをわずかな負圧に維持している。
【０１０１】
また、記録ヘッドとしてここでは各色のヘッド１２４を用いているが、各色のインク滴を吐出するノズルを有する１個のヘッドでもよい。
【０１０２】
ここで、キャリッジ１２３は後方側（用紙搬送方向下流側）を主ガイドロッド１２１に摺動自在に嵌装し、前方側（用紙搬送方向上流側）を従ガイドロッド１２２に摺動自在に載置している。そして、このキャリッジ１２３を主走査方向に移動走査するため、主走査モータ１２７で回転駆動される駆動プーリ１２８と従動プーリ１２９との間にタイミングベルト１３０を張装し、このタイミングベルト１３０をキャリッジ１２３に固定しており、主走査モーター１２７の正逆回転によりキャリッジ１２３が往復駆動される。
【０１０３】
一方、給紙カセット１１４にセットした用紙１１３をヘッド１２４の下方側に搬送するために、給紙カセット１１４から用紙１１３を分離給装する給紙ローラ１３１及びフリクションパッド１３２と、用紙１１３を案内するガイド部材１３３と、給紙された用紙１１３を反転させて搬送する搬送ローラ１３４と、この搬送ローラ１３４の周面に押し付けられる搬送コロ１３５及び搬送ローラ１３４からの用紙１１３の送り出し角度を規定する先端コロ１３６とを設けている。搬送ローラ１３４は副走査モータ１３７によってギヤ列を介して回転駆動される。
【０１０４】
そして、キャリッジ１２３の主走査方向の移動範囲に対応して搬送ローラ１３４から送り出された用紙１１３を記録ヘッド１２４の下方側で案内する用紙ガイド部材である印写受け部材１３９を設けている。この印写受け部材１３９の用紙搬送方向下流側には、用紙１１３を排紙方向へ送り出すために回転駆動される搬送コロ１４１、拍車１４２を設け、さらに用紙１１３を排紙トレイ１１６に送り出す排紙ローラ１４３及び拍車１４４と、排紙経路を形成するガイド部材１４５，１４６とを配設している。
【０１０５】
記録時には、キャリッジ１２３を移動させながら画像信号に応じて記録ヘッド１２４を駆動することにより、停止している用紙１１３にインクを吐出して１行分を記録し、用紙１１３を所定量搬送後次の行の記録を行う。記録終了信号または、用紙１１３の後端が記録領域に到達した信号を受けることにより、記録動作を終了させ用紙１１３を排紙する。この場合、ヘッド１２４を構成する本発明に係るインクジェットヘッドはインク滴噴射の制御性が向上し、特性変動が抑制されているので、安定して高い画像品質の画像を記録することができる。
【０１０６】
また、キャリッジ１２３の移動方向右端側の記録領域を外れた位置には、ヘッド１２４の吐出不良を回復するための回復装置１４７を配置している。回復装置１４７はキャップ手段と吸引手段とクリーニング手段を有している。キャリッジ１２３は印字待機中にはこの回復装置１４７側に移動されてキャッピング手段でヘッド１２４をキャッピングされ、吐出口部を湿潤状態に保つことによりインク乾燥による吐出不良を防止する。また、記録途中などに記録と関係しないインクを吐出することにより、全ての吐出口のインク粘度を一定にし、安定した吐出性能を維持する。
【０１０７】
吐出不良が発生した場合等には、キャッピング手段でヘッド１２４の吐出口（ノズル）を密封し、チューブを通して吸引手段で吐出口からインクとともに気泡等を吸い出し、吐出口面に付着したインクやゴミ等はクリーニング手段により除去され吐出不良が回復される。また、吸引されたインクは、本体下部に設置された廃インク溜（不図示）に排出され、廃インク溜内部のインク吸収体に吸収保持される。
【０１０８】
このように、このインクジェット記録装置においては本発明を実施したインクジェットヘッド又はインクカートリッジを搭載しているので、振動板駆動不良によるインク滴吐出不良がなく、安定したインク滴吐出特性が得られて、画像品質が向上する。また、低電圧で駆動できるヘッドを搭載するので、インクジェット記録装置全体の消費電力も低減できる。
【０１０９】
次に、本発明に係るマイクロポンプについて図２１を参照して説明する。なお、同図は同マイクロポンプの要部断面説明図である。
このマイクロポンプは、流路基板２０１と保護基板２０２とを重ねて接合した積層構造となっており、流路基板２０１には流体が流れる流路２０３を形成するとともに、流路２０３の一壁面を形成する変形可能な可動板２０４（ヘッドの振動板に相当する。）を設け、可動板２０４の保護基板２０２と接合固定しない部分は可動部分２０５となっている。
【０１１０】
そして、可動部分２０５には絶縁膜２０６を介して外面側に、前記インクジェットヘッドと同様に、複数の電極２０７（第２実施形態に係るヘッドの電極１４と同じ構成としている。）を所定の間隔を置いて設けている。保護基板２０２は前記ヘッドの第２基板２と同様な機能を有するものであり、電極２０７を配置するための凹部２０８を形成している。ここでは、保護基板２０２は平板板基板にスペーサ部２０９を設けることで凹部２０８を形成している。
【０１１１】
このマイクロポンプの動作原理を説明すると、前述したように複数の電極２０７に対して１つおきにパルス電位を与えることによって電極２０７間で静電吸引力が生じるので、可動部分２０５が流路２０３側に変形する。ここで、可動部分２０５を図中右側から順次駆動することによって流路２０３内の流体は、矢印方向へ流れが生じ、流体の輸送が可能となる。
【０１１２】
なお、この実施形態では可動部分を複数設けた例を示したが、可動部分は１つでも良い。また、輸送効率を上げるために、可動部分間に１又は複数の弁、例えば逆止弁などを設けることもできる。
【０１１３】
次に、本発明に係る光学デバイスの実施形態について図２２を参照して説明する。なお、同図は同デバイスの概略構成図である。
この光学デバイスは、変形可能なミラー３０１と保護基板３０２とを重ねて接合しており、ミラー３０１の保護基板３０２と接合固定しない部分は可動部分３０５となっている。そして、可動部分３０５には絶縁膜３０６を介して外面側に複数の電極３０７（第２実施形態のヘッドの電極１４と同じ構成としている。）を所定の間隔を置いて設けている。保護基板３０２は前記ヘッドの第２基板２と同様な機能を有するものであり、電極３０７を配置するための凹部３０８を形成している。ここでは、保護基板３０２は平板板基板にスペーサ部３０９を設けることで凹部３０８を形成している。なお、ミラー３０１表面は反射率を増加させるため誘電体多層膜や金属膜を形成すると良い。
【０１１４】
この光学デバイスの原理を説明すると、ミラー３０１の可動部分３０５に設けた複数の電極３０７に対して１つおきにパルス電位を与えることによって、電極３０７間で静電吸引力が生じるので、可動部分３０５が凸状に変形して凸面ミラーとなる。したがって、光源３１０からの光がレンズ３１１を介してミラー３０１に照射した場合、ミラー３０１を駆動しないときには、光は入射角と同じ角度で反射するが、ミラー３０１を可動部分３０５を駆動した場合はその可動部分３０５が凸面ミラーとなるので反射光は発散光となる。これにより光変調デバイスが実現できる。
【０１１５】
そこで、この光学デバイスを応用した例を図２３及び図２４をも参照して説明する。この例は、上述した光学デバイスを２次元に配列し、各ミラーの可動部分３０５を独立して駆動するようにしたものである。なお、ここでは、４×４の配列を示しているが、これ以上配列することも可能である。また、電極３０７は可動部分３０５の面において格子状に分離している（前記液滴吐出ヘッドの実施形態においても、この電極３０５と同様に、電極１４を格子状に分離することもできる。）。
【０１１６】
したがって、前述した図２２と同様に、光源３１０からの光はレンズ３１１を介してミラー３０１に照射され、ミラー３０１を駆動していないところに入射した光は、投影用レンズ３１２へ入射する。一方、電極３０７に電圧を印加してミラー３０１の可動部分３０５を変形させているところは凸面ミラーとなるので光は発散し投影用レンズ３１２にほとんど入射しない。この投影用レンズ３１２に入射した光はスクリーン（図示しない）などに投影され、スクリーンに画像を表示することができる。
【０１１７】
これらのマイクロポンプや光学デバイスの実施形態においては、第１実施形態に係るインクジェットヘッドと同様な構成のアクチュエータとしたが、第２実施形態以降の実施形態に係るインクジェットヘッドと同様な構成のアクチュエータとすることもできる。
【０１１８】
なお、上記実施形態においては、液滴吐出ヘッドとしてインクジェットヘッドに適用した例で説明したが、インクジェットヘッド以外の液滴吐出ヘッドとして、例えば、液体レジストを液滴として吐出する液滴吐出ヘッド、ＤＮＡの試料を液滴として吐出する液滴吐出ヘッドなどの他の液滴吐出ヘッドにも適用できる。また、マイクロアクチュエータは、マイクロポンプ、光学デバイス（光変調デバイス）以外にも、マイクロスイッチ（マイクロリレー）、マルチ光学レンズのアクチュエータ（光スイッチ）、マイクロ流量計、圧力センサなどにも適用することができる。また、電極を振動板の片面に設けた例で説明しているが、両面に設けることもできる。また、前述したようにプリンタ、ファクシミリ、複写装置等の画像形成装置及び液滴を吐出する装置にも本発明を適用することができる。
【０１１９】
【発明の効果】
以上説明したように、本発明に係る液滴吐出ヘッドによれば、振動板の面上には電気的に互いに絶縁分離された導電性を有する構造体からなる複数の電極が、振動板の面に沿って互いに間隔を置いて並べて設けられ、複数の電極は、一端部が振動板の面に固定された固定端部となり、他端部が固定されていない自由端部となっており、更に、電極は並び方向に沿う断面の形状で固定端部側が狭く、自由端部側が広い形状であって、複数の電極の間隔は固定端部側が自由端部側より広くなっており、電極間に静電力を発生させることによって振動板が変形する構成としたので、低コストで、滴吐出効率が高く、高画質印字が可能なヘッドが得られ、しかも振動板の変位効率を高くすることができて、低電圧駆動化を図れ、更に電極の機械的強度を保ちつつ電極を堆積膜で形成する場合に堆積の厚さを非常に厚くすることなく形成でき、プロセスコストの増加を抑制しつつ電極の高さを高くできて一層振動板を効率良く大きく変位させることができる。
【０１２０】
ここで、電極はポリシリコンを含むことで、容易に導電性を有する電極として作用する構造体を形成でき、更にエッチング加工で電極を形成する場合の制御性や異方性（垂直性）が向上して、高精度に電極を狭い間隔で形成できて、大きな静電気力を発生させることできるようになる。そして、ポリシリコンにはｎ型又はｐ型の不純物原子を含むことで、低抵抗化を図れ、より安定した高周波駆動、多チャンネル駆動を行うことが可能になる。また、電極には金属を含むことでも、低抵抗化を図れ、より安定した高周波駆動、多チャンネル駆動を行うことが可能になる。
【０１２１】
さらに、振動板の面上に電極の間隔の少なくとも一部を規定する犠牲層を形成して電極が形成された状態で、犠牲層がエッチング除去されることで電極の間が形成されている構成とでき、エッチング加工が困難な高アスペクトの（狭くて深い）溝形成でも可能となり、電極厚さが厚く（高さが高く）、電極間隔が狭い構造を形成できて、大きな静電気力を発生させることができる。この場合、電極に犠牲層エッチングのための開口部が設けることで、狭い電極間隔を有する電極を容易に高い歩留まりで形成することができるようになる。
【０１２２】
また、電極表面に絶縁膜を形成することで、電極間のショートによる動作不良を低減することができると共に、絶縁膜により実効的な電極間隔を減少させることができて大きな静電気力を発生させることができる。この絶縁膜をシリコン酸化膜とすることで、高耐圧の電極を容易に制御性良く形成することでき、絶縁膜をシリコン窒化膜とすることで、実効的な電極間隔を減少させることができて大きな静電気力を発生させることがきる。さらに、振動板と電極は電気的に分離することで、電極に印加した電圧が振動板側にリークして作動不能になることもなく、効率良く電極に電圧を印加できる。
【０１２３】
本発明に係るインクカートリッジによれば、インク滴を吐出する本発明に係る液滴吐出ヘッドとこの液滴吐出ヘッドにインクを供給するインクタンクを一体化したので、低コストで、滴吐出効率が高く、高画質印字が可能なヘッドを一体化でき、また製造不良が減少し、低コスト化を図ることができる。
【０１２４】
本発明に係るインクジェット記録装置によれば、インク滴を吐出するインクジェットヘッドが本発明に係る液滴吐出ヘッド又は本発明に係るインクカートリッジであるので、高画質記録を行うことができ、また装置の低コスト化を図れる。本発明に係る画像形成装置によれば、本発明に係る液滴吐出ヘッドを備えたので、高画質記録を行うことができる。本発明に係る液滴を吐出する装置によれば、本発明に係る液滴吐出ヘッドを備えたので、滴吐出効率が向上する。
【０１２５】
本発明に係るマイクロアクチュエータによれば、可動部分の面上には電気的に互いに絶縁分離された導電性を有する構造体からなる複数の電極が、可動部分の面に沿って互いに間隔を置いて並べて設けられ、複数の電極は、一端部が可動部分の面に固定された固定端部となり、他端部が固定されていない自由端部となっており、更に、電極は並び方向に沿う断面の形状で固定端部側が狭く、自由端部側が広い形状であって、複数の電極の間隔は固定端部側が自由端部側より広くなっており、電極間に静電力を発生させることによって可動部分が変形する構成としたので、低コストで、動作効率を向上し、低電圧駆動化を図れ、更に電極の機械的強度を保ちつつ電極を堆積膜で形成する場合に堆積の厚さを非常に厚くすることなく形成でき、プロセスコストの増加を抑制しつつ電極の高さを高くできて一層可動部分を効率良く大きく変位させることができる。
【０１２６】
本発明に係るマイクロポンプによれば、可動部分の変形によって液体を輸送するマイクロポンプであって、本発明に係るマイクロアクチュエータを備えているので、動作効率が高く、小型で、低消費電力化を図れるとともに、低コスト化を図れる。
【０１２７】
本発明に係る光学デバイスによれば、可動部分に形成したミラーの変位によって光の反射方向を変化させる光学デバイスであって、本発明に係るマイクロアクチュエータを備えているので、小型で、低消費電力化を図れるとともに、低コスト化を図れる。
【図面の簡単な説明】
【図１】本発明の液滴吐出ヘッドの第１実施形態に係るインクジェットヘッドの分解斜視説明図
【図２】同ヘッドの振動板長手方向の断面説明図
【図３】同ヘッドの振動板短手方向の要部拡大断面説明図
【図４】同ヘッドの電極部分の拡大説明図
【図５】同ヘッドの電極配置パターンを説明する平面説明図
【図６】同ヘッドの作用説明に供する要部拡大断面説明図
【図７】同ヘッドの製造工程の一例を説明する説明図
【図８】同第２実施形態に係るインクジェットヘッドの説明に供する図７（ｄ）に相当する工程の平面説明図
【図９】同ヘッドの製造工程の説明に供する図７（ｄ）、（ｅ）に相当する図８のＡ−Ａ線に沿う断面説明図
【図１０】同第３実施形態に係るインクジェットヘッドをその製造工程とともに説明する断面説明図
【図１１】図１０に続く工程を説明する説明図
【図１２】図１１（ｂ）の工程の他の例を説明する断面説明図
【図１３】同第３実施形態に係るインクジェットヘッドをその製造工程と共に説明する断面説明図
【図１４】同ヘッドのシリコン酸化膜の作用説明に供する電極部分の拡大説明図
【図１５】同実施形態の他の例を説明する断面説明図
【図１６】同他の例のシリコン酸化膜の作用説明に供する電極部分の拡大説明図
【図１７】同第４実施形態に係るインクジェットヘッドの説明に供する電極部分の拡大説明図
【図１８】本発明に係るインクカートリッジの説明に供する斜視説明図
【図１９】本発明に係るインクジェット記録装置の一例を説明する斜視説明図
【図２０】同記録装置の機構部の説明図
【図２１】本発明に係るマイクロポンプの実施形態を説明する断面説明図
【図２２】本発明に係る光学デバイスの実施形態を説明する断面説明図
【図２３】同光学デバイスを用いた光変調デバイスの一例を説明する斜視説明図
【図２４】同光変調デバイスの要部斜視説明図
【符号の説明】
１…第１基板、２…第２基板、３…ノズル板、４…ノズル孔、６…吐出室、７…流体抵抗部、８…共通液室、１０…振動板、１４…電極、１００…インクカートリッジ、２０１…流路基板、２０３…流路、２０５…可動部分、２０７…電極、３０１…ミラー、３０５…可動部分、３０７…電極。[0001]
[Industrial application fields]
  The present invention relates to a droplet discharge head, an ink cartridge, an ink jet recording apparatus, a microactuator, a micropump, and an optical device., Image forming apparatus, and apparatus for ejecting liquid dropletsAbout.
[0002]
[Prior art]
An ink jet head, which is a liquid droplet ejection head used in an image recording apparatus such as a printer, a facsimile machine, a copying apparatus, or the like or an image forming apparatus, has a single or a plurality of nozzle holes for ejecting ink droplets, and the nozzle holes. A discharge chamber (also referred to as an ink chamber, a liquid chamber, a pressurized liquid chamber, a pressure chamber, an ink flow path, etc.) communicating with the pressure chamber, and a pressure generating means for generating a pressure for pressurizing the ink in the discharge chamber. Ink droplets are ejected from the nozzle holes by pressurizing the ink in the ejection chamber with the pressure generated by the pressure generating means.
[0003]
Examples of the droplet discharge head include a droplet discharge head that discharges a liquid resist as a droplet, and a droplet discharge head that discharges a DNA sample as a droplet. The following description will focus on an inkjet head. . Also, microactuators constituting the actuator part of the droplet discharge head, for example, optical devices such as micropumps and micro light modulation devices, micro switches (micro relays), actuators for multi optical lenses (optical switches), micro flow meters, pressures It can also be applied to sensors and the like.
[0004]
By the way, as a droplet discharge head, a piezoelectric type that discharges ink droplets by deforming and displacing a vibration plate forming a wall surface of a discharge chamber using an electromechanical conversion element such as a piezoelectric element as pressure generating means. A bubble type (thermal type) that discharges ink droplets by generating bubbles by boiling an ink film using an electrothermal conversion element such as a heating resistor disposed in the discharge, and forming the wall surface of the discharge chamber There is an electrostatic type that ejects ink droplets by deforming a diaphragm with an electrostatic force.
[0005]
In recent years, bubble-type and electrostatic types that are lead-free have attracted attention due to environmental problems, and in addition to lead-free, a plurality of electrostatic types that have little influence on the environment from the viewpoint of low power consumption have been proposed.
[0006]
Some of these electrostatic heads are driven by a pushing method in which ink droplets are ejected by pushing the vibration plate into the ink chamber side to reduce the internal volume of the ink chamber, and the vibration plate in the direction outside the ink chamber. Some of them are driven by a striking method in which ink droplets are ejected by returning the displacement of the diaphragm so that the inner volume of the ink chamber is expanded from the state in which the inner volume is expanded by the force of.
[0007]
As a press-type electrostatic head, for example, as described in Japanese Patent Application Laid-Open No. 2-266944, ink is filled between a pair of electrodes, and one or both electrodes are diaphragms. In some cases, electrostatic attraction works between the electrodes by applying a voltage between the electrodes, and the electrodes (vibrating plates) are deformed, thereby ejecting and ejecting ink. Further, as described in Japanese Patent Application Laid-Open No. 2000-15805, a protrusion is provided on the surface of a diaphragm made of a silicon substrate, an electrode is formed on the protrusion, and a voltage is applied to the electrodes, thereby providing a gap between the protrusions. In some cases, the diaphragm is deformed by an electrostatic force acting on the ink, and ink is ejected.
[0008]
For example, as described in JP-A-6-71882, a pair of electrode pairs are provided via an air gap, and one electrode functions as a diaphragm, and the diaphragm is opposed to the diaphragm. An ink chamber filled with ink is formed on the opposite side of the electrode to be applied. By applying a voltage between the electrodes (between the diaphragm and the electrode), an electrostatic attractive force acts between the electrodes, and the electrode (the diaphragm) is deformed. In some cases, when the voltage is removed, the diaphragm returns to its original state by an elastic force, and ink is ejected using the force. Further, as described in Japanese Patent Application Laid-Open No. 2001-47624, a vibration plate is provided on one side of an electrode pair which is formed in a comb shape and is nested, and a voltage is applied to the electrode pair so In some cases, an electrostatic force is generated at the same time, the diaphragm is deformed by the displacement of the electrode, and ink is ejected by the elastic force of the diaphragm when the voltage is turned off.
[0009]
[Problems to be solved by the invention]
However, in the liquid droplet ejection head described in Japanese Patent Application Laid-Open No. 2-26643, the distance between the electrodes is inevitably increased because the ink is filled between the electrodes. Since the electrostatic force acting between the electrodes is inversely proportional to the square of the distance between the electrodes, there is a problem that the required voltage becomes very large as the distance between the electrodes increases. In this case, the voltage can be lowered to some extent depending on the dielectric constant of the ink, but it is not very effective because the influence of the distance between the electrodes is large. In addition, the degree of freedom of the ink is reduced because the dielectric constant of the ink needs to be increased or an electric field is applied to the ink. For this reason, there is a problem in that it is difficult to improve image quality due to restrictions on ink physical properties such as ink color, pH, and viscosity.
[0010]
Further, in the liquid droplet ejection head described in JP-A-6-71882, ink is not filled between the electrodes, so there are few restrictions on the ink and it is advantageous for high image quality. However, in order to reduce the voltage, the air gap between the electrodes must be made very small. It is very difficult to form such a small gap with high accuracy and little variation, and the yield does not increase. There is a problem. In addition, since the ink is ejected by the elastic force of the diaphragm, it is a so-called striking method. Therefore, the diaphragm needs to be rigid enough to eject ink, and the voltage is used to attract such a rigid diaphragm with electrostatic force. There is a problem that becomes high.
[0011]
Further, in the droplet discharge head described in Japanese Patent Laid-Open No. 2001-47624, since the comb-like electrode is used, the displacement can be increased, but the generated force is very small and the ink is discharged. If you try to get enough power to generate, the voltage will be very high. Moreover, since the structure is complicated, it is difficult to manufacture, and there is a problem that the cost becomes high.
[0012]
Further, in the droplet discharge head described in Japanese Patent Laid-Open No. 2000-15805, a protrusion is provided on a diaphragm formed of a conductive silicon substrate, and an electrode of a conductive member is formed on the protrusion. Therefore, there is a problem that the electrodes have the same potential through the silicon diaphragm and no electrostatic force is generated, and the diaphragm cannot be deformed.
[0013]
Moreover, it is necessary to form a protrusion on the diaphragm and attach an electrode to this protrusion, and it is difficult to attach an electrode to the surface of such a three-dimensional microstructure, and there is a portion where the electrode is not well formed. There is a problem that the production cannot be stably performed and the yield is poor due to variations or variations. Furthermore, in order to reduce the voltage, the interval between the protrusions must be narrowed. However, it is difficult to form an electrode in such a narrow interval, and if an electrode is formed between the narrow protrusions, a short circuit occurs. Defects that occur may occur.
[0014]
In addition, it is impossible to form electrodes on the protrusions by a general method because a photolithographic process with a three-dimensional structure is difficult to perform resist coating, exposure, etc. There is a problem that the manufacturing process becomes long and the cost becomes high.
[0015]
  The present invention has been made in view of the above problems, and is a low-cost, high-efficiency droplet-discharging head capable of high-quality printing, an ink cartridge that integrates this head, and high-quality recording. Inkjet recording device, low cost, high driving efficiency microactuator, micropump, optical device, Image forming device capable of high-quality recording, device for ejecting droplets with high droplet ejection efficiencyThe purpose is to provide.
[0016]
[Means for Solving the Problems]
  In order to solve the above problems, a liquid droplet ejection head according to the present invention includes a diaphragm.On the surfaceA plurality of electrodes composed of electrically conductive structures that are electrically isolated from each otherThe plurality of electrodes are arranged side by side along the plane of the diaphragm, and the plurality of electrodes are fixed ends with one end fixed to the plane of the diaphragm, and the free end with the other end not fixed Furthermore, the electrode has a shape of a cross section along the alignment direction, the fixed end side is narrow, the free end side is wide,The interval between the plurality of electrodes is wider on the fixed end side than on the free end side, and a diaphragm is generated by generating an electrostatic force between the electrodes.ButDeformationYouRuThe configuration.
[0017]
  Here, the electrode preferably includes polysilicon, and the polysilicon preferably includes n-type or p-type impurity atoms. The electrode preferably contains a metal. further,A sacrificial layer that defines at least part of the distance between the electrodes is formed on the surface of the diaphragm, and the electrodes are formed, and the sacrificial layer is etched away to form a space between the electrodes.It is preferable. Furthermore, it is preferable that an opening is formed in the electrode.
[0018]
In addition, an insulating film is preferably formed on the electrode surface, and it is more preferable that the insulating film includes a silicon oxide film or a silicon nitride film. Furthermore, it is preferable that the diaphragm and the electrode are electrically separated.
[0019]
The ink cartridge according to the present invention is obtained by integrating the droplet discharge head according to the present invention that discharges ink droplets and an ink tank that supplies ink to the droplet discharge head.
[0020]
  An ink jet recording apparatus according to the present invention includes a droplet discharge head according to the present invention that discharges ink droplets or an ink cartridge according to the present invention.powered byIt is a thing.
  The image forming apparatus and the apparatus for ejecting droplets according to the present invention include the droplet ejection head according to the present invention.
[0021]
  A microactuator according to the present invention is a microactuator that deforms a plate-shaped movable part, and a plurality of electrodes made of electrically conductive structures that are electrically insulated and separated from each other on the surface of the movable part,Moving partsThe plurality of electrodes are provided as fixed ends with one end fixed to the surface of the movable part, and the other ends are free ends that are not fixed. Furthermore, the electrode has a cross-sectional shape along the alignment direction, the fixed end side is narrow, the free end side is wide, and the interval between the plurality of electrodes is wider at the fixed end side than the free end side. The movable part is deformed by generating an electrostatic force between them.
[0022]
The micropump according to the present invention is a micropump that transports liquid by deformation of a movable part, and includes the microactuator according to the present invention.
[0023]
The optical device according to the present invention is an optical device that changes the reflection direction of light by displacement of a mirror formed in a movable part, and includes the microactuator according to the present invention.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an exploded perspective view of the ink jet head according to the first embodiment of the droplet discharge head of the present invention, and is a partial cross-sectional view. 2 is a sectional view of the head in the longitudinal direction of the diaphragm, FIG. 3 is a sectional view of the head in the lateral direction of the diaphragm, FIG. 4 is an enlarged view of the electrode portion of FIG. 3, and FIG. It is a plane explanatory view showing an electrode arrangement pattern.
[0025]
This ink jet head is of a side shooter type that discharges ink droplets from nozzle holes provided on the surface of the substrate, and includes three first, second, and third substrates 1 having the structure described in detail below. A plurality of nozzle holes 4 for discharging ink droplets, a discharge chamber 6 in which each nozzle hole 4 communicates, and each discharge chamber 6 via a fluid resistance portion 7 A common liquid chamber (common ink chamber) 8 for supplying the liquid is formed.
[0026]
The intermediate first substrate 1 is made of a silicon substrate and has a recess (penetrating portion) for forming a discharge chamber 6 having a bottom wall as a vibration plate 10 and a common liquid for supplying ink to each discharge chamber 6. A recess (penetrating portion) for forming the chamber 8 is provided.
[0027]
The diaphragm 10 is made of an insulating film such as a silicon nitride film, a silicon nitride film, or a laminated film thereof. A plurality of electrodes 14 are formed at a predetermined interval on the surface of the diaphragm 10 opposite to the discharge chamber 6, and the diaphragm 10 and each electrode 14 are electrically separated and provided. Two adjacent electrodes of the electrode 14 (which are relatively referred to as electrodes 14a and 14b) are electrically separated from each other. The electrode 14 is made of, for example, polysilicon or single crystal silicon. The diaphragm 10 and the plurality of electrodes 14 constitute a microactuator according to the present invention that deforms the diaphragm 10 that is a movable part.
[0028]
  Here, as shown in FIG. 3 and FIG.In cross-sectional shape in the direction of electrode 14 alignmentThe width of the fixed end portion 14A (here, the width in the short side direction of the diaphragm) fixed to the diaphragm 10 side is narrower than the width of the intermediate portion 14B, and the width of the intermediate portion 14B is narrower than the width of the free end portion 14C. It is formed to become. That is, the distance between the electrodes 14 and 14 is such that the fixed end side of the electrode is wider than the free end side, that is, as shown in FIG. 5, the distance d1 on the fixed end side of the electrode, The distance d2 and the distance d3 on the free end side are formed such that d1> d2> d3. In the figure, L is the height of the electrode 14.
[0029]
FIG. 4 shows an example of an electrode arrangement pattern for one diaphragm when viewed from the electrode 14 side of the first substrate 1. As shown in the figure, drive voltages (voltages of different potentials) are applied to adjacent electrodes 14a and 14b that are electrically separated from each other from a drive circuit 15 (shown here as a transmission circuit). It has come to be.
[0030]
Further, the spacer 12 which is a layer or a structure of the same material as the electrode 14 is formed in substantially the same plane as the surface on which the electrode 14 is formed in a region other than the diaphragm 10. The spacer 12 can be formed at the same time as the electrode 14 and can be formed without removing the electrode material other than the diaphragm region.
[0031]
By providing such a spacer 12, it is possible to protect the electrode 14 which is a minute structure in the process before the first substrate 1 is bonded to the second substrate 2, and in the manufacturing process, the wafer is transported or during the process. Defects due to breakage of the electrode 14 can be reduced.
[0032]
The second substrate 2 bonded to the lower surface of the first substrate 1 is a protective substrate for protecting the electrode 14 from external impacts and dust, and reinforcing the strength of the first substrate 1. For the second substrate 2, a substrate made of glass, metal, silicon, resin, or the like is used. A concave portion 16 having a depth of 1 mm, for example, is formed on the substrate 2 at a position corresponding to each vibration plate 10. Yes. However, it is not always necessary to form the concave portion 16 for each diaphragm 10, and a configuration in which a concave portion surrounding the diaphragm array or a concave portion joined only to the edge of the chip may be formed.
[0033]
Further, as the third substrate 3 bonded to the upper surface of the first substrate 1, for example, a nickel substrate having a thickness of 50 μm is used, and the nozzle hole 4, A groove serving as a fluid resistance portion 7 for communicating the common liquid chamber 8 and the discharge chamber 6 is provided, and an ink supply port 9 is provided so as to communicate with the common liquid chamber 8.
[0034]
The operation of the ink jet head configured as described above will be described. For example, in the configuration of FIG. 4, when a pulse potential of 0V to 40V is applied to the electrode 14a by the oscillation circuit 15, the surface of the electrode 14a is positively charged, and between the adjacent electrodes 14b to which no pulse potential is applied, As shown in FIG. 6, electrostatic force is generated and electrostatic attraction works, the free ends of the electrodes 14 (the diaphragm 10 side is the fixed end) are attracted and the electrodes 14 are displaced, and the free ends of these electrodes 14 When the side is displaced, the diaphragm 10 which is the fixed end side of the electrode 14 bends upward. As a result, the pressure in the discharge chamber 6 increases rapidly, and the ink droplets 22 are discharged from the nozzle holes 4 toward the recording paper 23 as shown in FIG.
[0035]
When the potential of the electrode 14a returns to 0V, there is no potential difference with the electrode 14b, and the diaphragm 10 is restored to the original state. When the diaphragm 10 is restored, ink is supplied from the common liquid chamber 8 into the discharge chamber 6 through the fluid resistance portion 7. In other words, in this embodiment, ink droplets are ejected by the pushing method.
[0036]
As described above, in this ink jet head, the electrodes 14 that are electrically separated and independent from each other are provided on one surface of the diaphragm 10, and a voltage that generates a potential difference between the electrodes 14 a and 14 b facing each other is applied. As a result, an electrostatic attractive force is generated between the adjacent electrode 14a and the electrode 14b, and a large displacement of the diaphragm 10 can be obtained by a slight displacement of the electrode 14, so that the droplet discharge efficiency is improved and high image quality recording is achieved. It becomes possible.
[0037]
Further, in the microactuator of this head, the structure itself provided on the vibration plate 10 functions as the electrode 14, so that it is necessary to have a difficult process of forming the electrode on the silicon structure by a method such as film formation as before. Therefore, it is possible to reduce the cost, and it is possible to reduce defects such as a short circuit caused by forming electrodes at very narrow intervals between structures. Further, there is no need for a process of separating the electrodes into comb-like shapes after forming the electrodes on the structure, and cost reduction and mass production are easy.
[0038]
Further, since the diaphragm 10 and the electrode 14 are electrically separated by the insulating film 11 or the like, even if a voltage is applied to the electrode as in the prior art, all the electrodes are operated at the same potential via the diaphragm. Without being defective, the voltage applied to the electrode 14 does not leak to the diaphragm 10 side, and the voltage can be efficiently applied to the electrode 14. In this case, although the diaphragm 10 itself is formed of an insulating film, the diaphragm 10 is formed of a high-concentration p-type impurity layer formed on a silicon substrate (this is referred to as a silicon diaphragm). By forming an insulating film between the silicon diaphragm and the electrode 14, it is possible to easily insulate and obtain a highly reliable droplet discharge head.
[0039]
Here, the force F acting between the electrodes increases in inverse proportion to the square of the distance d between the electrodes as shown in the following equation (1), and the bending moment acting on the diaphragm is the height of the structure (electrode). It increases in proportion to L. Therefore, in order to displace the diaphragm efficiently, it is important to form a narrow gap between the electrode 4a and the electrode 4b at a position away from the diaphragm (height L is large).
[0040]
[Expression 1]

[0041]
In the equation (1), F: force acting between electrodes, ε: dielectric constant, S: area of opposing surfaces of electrodes, d: distance between electrodes, and V: applied voltage.
[0042]
In addition, since the electrode (structure) itself does not bend, the deformable region of the diaphragm is enlarged by forming a wide electrode interval at the base of the electrode (structure) (fixed end fixed to the diaphragm). Therefore, the diaphragm can be displaced efficiently.
[0043]
Therefore, the diaphragm is configured such that the distance between the electrodes (electrode spacing) is wide on the diaphragm side (electrode fixed end side) and narrower on the side away from the diaphragm (electrode free end side). It can be displaced greatly efficiently.
[0044]
In order to displace the diaphragm more effectively and efficiently, it is preferable to increase the height L of the structure (electrode) as described above. In this case, if it is necessary to deposit a very thick film in order to form the structure, the process cost increases, and it becomes difficult to form a narrow electrode interval by etching or the like. If the deposited film is thin, the mechanical strength of the structure is weakened, and the diaphragm cannot be displaced efficiently, or the yield may be reduced due to destruction of the structure itself.
[0045]
Therefore, in the head according to the present embodiment, the electrode interval is varied in a plurality of stages, particularly three or more stages, and the electrode interval is wide on the fixed end side and narrow on the free end side. The electrode can be formed without significantly increasing the thickness of the deposited film while maintaining the desired strength, and the height L of the structure is increased while suppressing an increase in process cost. The large displacement can be efficiently performed.
[0046]
Next, an example of the manufacturing process of the inkjet head according to the first embodiment will be described with reference to FIG.
As shown in FIG. 6A, a silicon nitride film 32 to be a vibration plate 10 is formed to a thickness of 0.3 μm by LP-CVD on a silicon substrate 31 having a plane orientation (110) and a thickness of 400 μm, and silicon is formed by plasma CVD. The oxide film 33a is formed to a thickness of 2 μm, and the silicon oxide film 33a is patterned by known lithography and dry etching techniques, thereby forming the silicon oxide film 33a having a line width of 10 μm and an interval of 2 μm. Here, the silicon nitride film 32 functions as an etching stopper when the silicon oxide film 33a is etched. The silicon oxide film may be formed by low temperature thermal CVD or high temperature CVD.
[0047]
Next, as shown in FIG. 2B, a silicon oxide film 33b is formed to a thickness of 2 μm on the silicon oxide film 33a, and similarly, the silicon oxide film 33b is patterned by known lithography and dry etching techniques. A silicon oxide film 33b having a line width of 8 μm and an interval of 4 μm was formed.
[0048]
Thereafter, as shown in FIG. 2C, a polysilicon film 34 for forming the electrode 14 on the surface is deposited to a thickness of 3 μm by the CVD method. The thickness of the polysilicon film required for obtaining the planarization of the buried substrate with the interval between the silicon oxide films 33b being 2 μm or more. That is, here, the filling requirement is satisfied, and the substrate is also almost flattened. Here, the height L of the polysilicon film 34 to be an electrode is about 7 μm from the surface of the silicon nitride film 32 to be the vibration plate 10, but since the two-stage silicon oxide films 33 a and 33 b are formed, the polysilicon is formed. Since the thickness of depositing the film 34 is thinner than that of the single silicon oxide film 33a, the process cost is reduced.
[0049]
Although not shown, the silicon nitride film 32, the silicon oxide films 33a and 33b, and the polysilicon film 34 that are also formed on the back surface side of the silicon substrate 31 in the above process are polished (a polishing process using lapping or a grinder). It is preferable to include all of them. At this time, it is preferable to protect the surface of the polysilicon film 34 with a protective film (protective tape) or the like. Further, it is not limited to polishing and may be removed by an etching solution or the like.
[0050]
Next, as shown in FIG. 4D, a trench 35 having a width of 0.5 μm is formed in the polysilicon film 34 on the silicon oxide film 33b by lithography and dry etching techniques. In this case, the silicon oxide film 33b functions as an etching stopper.
[0051]
Thereafter, as shown in FIG. 5 (e), the silicon oxide films 33a and 33b are etched away with a hydrofluoric acid aqueous solution or the like, so that the distance between the electrodes differs in three steps (d1, d2, d3), and the diaphragm side ( An electrode 14 made of a polysilicon film 34 is formed, which is made of a structure having a wide inter-electrode distance d1 on the fixed end side) and a narrow inter-electrode distance d3 on the side far from the diaphragm (free end side).
[0052]
Since this electrode 14 is gradually widened (in this case, the width in the lateral direction of the diaphragm) in a stepwise manner (in this case, the width in the lateral direction of the diaphragm), the mechanical strength is greater than that of electrodes having different widths in two stages. It can be displaced well and the yield can be improved. Here, the structure in which the distance between the electrodes is different in three stages is used, but a structure in which the distance between the electrodes is different in four or more stages may be used.
[0053]
Thereafter, as shown in FIG. 5F, a silicon nitride film serving as a mask for potassium hydroxide etching is formed by LP-CVD, the silicon substrate 31 is etched with an aqueous potassium hydroxide solution, and silicon nitride is simultaneously formed with the discharge chamber 6. The diaphragm 10 made of the film 34 is formed.
[0054]
Here, the diaphragm 10 made of the silicon nitride film 34 functions as an etching stopper, and is also an insulating film, so that it is electrically separated from the electrode 14. Since the silicon nitride film has a tensile stress, the diaphragm does not buckle, but the diaphragm 10 may not be deformed by the tensile stress. In such a case, the stress can be relieved by doping the silicon nitride film with impurities such as boron, phosphorus and hydrogen.
[0055]
Further, by forming the electrodes from polysilicon, the electrode spacing can be formed with relatively high accuracy by dry etching. However, when the non-doped polysilicon is driven at a high frequency and multi-channel, the electric resistance value of the electrode may become a problem. In this case, the electrical resistance can be reduced by introducing impurity atoms having n-type or p-type conductivity, such as phosphorus or arsenic for n-type or boron or antimony for p-type. preferable.
[0056]
Next, an inkjet head according to a second embodiment will be described with reference to FIGS. 8 is an explanatory view corresponding to the plan view of FIG. 7D in the manufacturing process of the head, and FIG. 9 is a cross-sectional explanatory view along the AA line of FIG. 8 in the manufacturing process of the head.
[0057]
In this embodiment, an opening 36 is formed in the electrode 14. That is, after passing through the same manufacturing steps as in FIGS. 7A to 7C, the polysilicon film 34 on the silicon oxide film 33b is formed by lithography and dry etching techniques as shown in FIGS. 8 and 9A. A groove having a width of 0.5 μm is formed, and a plurality of openings 36 having a width of 1.5 μm and a length of several μm are formed. The opening 36 may be formed continuously with the inter-electrode groove 35 or may be formed independently.
[0058]
Thereafter, as shown in FIG. 9B, the silicon oxide films 33a and 33b are removed, whereby the electrode 14 having the opening 36 is formed.
[0059]
By providing the opening 36 in the electrode 14 in this way, the area where the silicon oxide film is exposed can be increased, and the silicon oxide films 33a and 33b, which are sacrificial layers, can be easily removed by etching.
[0060]
Next, an inkjet head according to a third embodiment will be described with reference to FIGS.
First, as shown in FIG. 10A, a thermal oxide film 42 is formed to a thickness of 0.2 μm on a silicon substrate 41 having a plane orientation (110) and a thickness of 400 μm, and then a silicon nitride film 43 is formed by LP-CVD. Is formed with a thickness of 0.3 μm. Then, a silicon oxide film 44a having a thickness of 2 μm is formed by plasma CVD, and a silicon oxide film 44a having a line width of 10 μm and an interval of 2 μm is formed by patterning the silicon oxide film 44a by known lithography and dry etching techniques. did. Here, the silicon nitride film 43 functions as an etching stopper when the silicon oxide film 44a is etched.
[0061]
Further, a silicon oxide film 44b having a thickness of 2 μm is formed on the silicon oxide film 44a, and a silicon oxide film 44b having a line width of 8 μm and an interval of 4 μm is formed by patterning the silicon oxide film 44b by known lithography and dry etching techniques. did. The silicon oxide film may be formed by low temperature thermal CVD or high temperature CVD. Subsequently, a polysilicon film 45a is deposited on the surface of the silicon oxide film 44b to a thickness of 3 μm by the CVD method.
[0062]
Thereafter, as shown in FIG. 4B, a groove 46 having a width of 1.5 μm is formed in the polysilicon film 45a on the silicon oxide film 44b by lithography and dry etching techniques. Here, since the groove width of the groove 46 is relatively wide and the aspect is not high, the groove can be easily formed with good controllability.
[0063]
Then, as shown in FIG. 3C, a silicon oxide film is formed to a thickness of 0.2 μm on the entire surface by CVD. The silicon oxide film may be formed by low-temperature thermal CVD, high-temperature CVD, or plasma CVD, but it can be formed in a very conformal manner by low-temperature thermal CVD.₃-A TEOS film is preferred. Silicon oxide films 47a and 47b are formed on the sidewalls of the polysilicon film 45 by etching back the silicon oxide film.
[0064]
Next, as shown in FIG. 4D, after a polysilicon film 45b is deposited on the surface, a resist is formed on the surface of the polysilicon film 45b, leaving the resist on the silicon oxide film 47a, and on the silicon oxide film 47b. The resist 48 is patterned so as to open the resist.
[0065]
Thereafter, as shown in FIG. 11A, the polysilicon film 45b is etched until the silicon oxide film 47b is exposed, and the polysilicon film 45b is patterned. Thereafter, the resist 48 is removed.
[0066]
Next, as shown in FIG. 2B, the silicon oxide film 47b and the silicon oxide films 44a and 44b are removed by etching with a hydrofluoric acid aqueous solution or the like, thereby forming the electrode.
[0067]
Here, the silicon oxide film 47b is a sacrificial layer, and the electrode interval is formed by etching the sacrificial layer. In other words, since the electrode spacing is defined by the thickness of the sacrificial layer, high-aspect grooves that are difficult to etch can be formed with high accuracy. The silicon oxide film 47a may remain or be removed here.
[0068]
Thereafter, as shown in FIG. 6C, the silicon resist 41 is etched simultaneously with the discharge chamber 6 by using the patterned resist as a mask and dry etching using high-density plasma. The diaphragm 10 made of the nitride film 43 is formed. Here, the silicon oxide film 42 functions as an etching stopper. Further, the silicon oxide film 42 may be removed after etching.
[0069]
The patterning of the polysilicon film 45b is merely an example, and another example is shown in FIG. 12, but is not limited thereto.
[0070]
Next, an inkjet head according to a fourth embodiment will be described with reference to FIG.
As shown in FIG. 5A, a silicon nitride film 52 to be the vibration plate 10 is formed to a thickness of 0.3 μm by LP-CVD on a silicon substrate 51 having a plane orientation (110) and a thickness of 400 μm, and silicon is formed by plasma CVD. An oxide film 53a is formed to a thickness of 2 μm, and the silicon oxide film 53a is patterned by known lithography and dry etching techniques to form a silicon oxide film 53a having a line width of 14 μm and an interval of 2 μm. Here, the silicon nitride film 52 functions as an etching stopper when the silicon oxide film 53a is etched. The silicon oxide film may be formed by low temperature thermal CVD or high temperature CVD. Further, a silicon oxide film 53b is formed with a thickness of 3 μm, and the silicon oxide film 53b is patterned by a known lithography and dry etching technique to form a silicon oxide film 53b having a line width of 6 μm and an interval of 8 μm.
[0071]
Thereafter, as shown in FIG. 2B, a polysilicon film 54 is deposited on the surface to a thickness of 3 μm by the CVD method. The thickness of the polysilicon film 54 required for obtaining the planarization of the buried substrate with the interval between the silicon oxide films 53b being 4 μm or more. Therefore, here, a recess 55 is formed in the polysilicon film 54.
[0072]
Then, a groove 56 having a width of 0.5 μm is formed in the polysilicon film 54 on the silicon oxide film 53b by lithography and dry etching techniques. Here, the silicon oxide film 53b functions as an etching stopper.
[0073]
Thereafter, as shown in FIG. 3C, the silicon oxide films 53a and 53b are etched away with a hydrofluoric acid solution or the like, whereby the inter-electrode distance d is changed in three stages (d1, d2, d3), and the diaphragm side The electrode 14 is formed of a structure in which the inter-electrode distance d1 is large and the inter-electrode distance d3 on the side away from the diaphragm is narrow. Note that, here, the distance between the electrodes is different in three stages, but it may be four or more stages.
[0074]
Next, as shown in FIG. 4D, an insulating film 57 is formed on the surface of the electrode 14. That is, in order to reduce the driving voltage (to obtain a large electrostatic force), the interval between the electrodes 14 must be reduced. Otherwise, a short circuit may occur and malfunction may occur. In addition, since the intervals are very minute, a short circuit may occur even if minute water droplets are generated on the surface of the electrode 14 due to the humidity of the air. Therefore, by providing the insulating film 57 on the surface of the electrode 14, it is possible to reduce malfunction due to a short circuit between the electrodes.
[0075]
Also, malfunction may occur due to discharge between electrodes when a voltage is applied. By providing the insulating film 57, the breakdown voltage can be improved and a highly reliable droplet discharge head can be obtained.
[0076]
In this case, the insulating film 57 is made of a silicon oxide film having excellent insulating properties, whereby an electrode having a high withstand voltage and high reliability can be formed, and it is technically established to be generally used in a semiconductor process. Since there are various types of formation methods, formation with good controllability is possible.
[0077]
Here, a silicon oxide film which is the insulating film 57 is formed by a CVD method. By forming by the CVD method, it can be formed relatively uniformly. However, since it is also formed on the diaphragm 10, there is a demerit that the rigidity of the diaphragm 10 is increased and the diaphragm itself is difficult to displace, but the dielectric constant is relatively large and the effective gap is efficiently reduced. it can.
[0078]
That is, as shown in FIG. 14, when a silicon oxide film is formed by high-temperature CVD, the silicon oxide film is deposited on the deposition surface. The electrode surface of this does not change. Therefore, when the silicon oxide film is formed by the thickness t, the electrode interval G1 before and after the film formation does not change, and the space interval becomes G2 which is narrowed by the film thickness.
[0079]
Here, the effective gap G, which is the electrical inter-electrode spacing before forming the deposited insulating film (oxide film) 57, is G = G1. The effective gap G 'when the oxide film 57 having the thickness t is formed is expressed by the following equation (2), where ε1 is the dielectric constant of the oxide film.
[0080]
[Expression 2]

[0081]
Since the dielectric constant ε1 of the silicon oxide film by high-temperature CVD is 4.0 to 4.5, G ′ <G, and the effective gap can be reduced by forming the oxide film (deposited insulating film). . The dielectric constant of the oxide film used here was 4.0. When G1 is 0.5 μm and t is 0.2 μm, G ′ becomes 0.2 μm and the effective gap can be reduced to 2/5. When the electrostatic force acting between the electrodes is converted from the above-described equation (1), it becomes six times, and when trying to obtain the same electrostatic force, the voltage can be reduced to 2/5.
[0082]
That is, when G1 = 0.5 μm (ε = 4.0)
When t = 0.2 μm: G2 = 0.1 μm, G ′ = 0.2 μm
It becomes.
[0083]
The higher the dielectric constant, the greater the effect of reducing the effective gap. In addition, the effect of reducing the effective gap becomes larger by using a film having a larger dielectric constant such as a silicon oxide film of PE-CVD.
[0084]
Further, as shown in FIG. 15, the silicon oxide film can be used as the thermal oxide film 58. The thermal oxide film 58 is not formed on the vibration plate 10 made of the silicon nitride film 52 which is an oxidation resistant film, and even in a structure having a narrow interval, the uniformity in film formation is excellent. However, since the thermal oxide film 58 is grown while consuming about 44% of silicon, the efficiency of effective gap reduction is lower than that of the deposited film described above.
[0085]
That is, as shown in FIG. 16, the electrode 14 before the thermal oxide film 58 is formed (before oxidation) is in a state indicated by a dotted line A, and is provided with a gap G1 therebetween. If a thermal oxide film 58 having a thickness t is formed on this, silicon having a thickness of about 0.44 t is consumed, and the gap between the electrodes 14 is G3 and the spatial gap is G2.
[0086]
The effective gap G, which is the electrical inter-electrode spacing before forming the thermal oxide film 58, is G = G1, and the effective gap G ′ when the thermal oxide film 58 of thickness t is formed is the thermal oxide film. Is expressed by the following equation (3).
[0087]
[Equation 3]

[0088]
Here, since the dielectric constant ε of the thermal oxide film is 3.7 to 3.9, G ′ <G, and the effective gap can be reduced by forming the thermal oxide film. As a result, the effective gap is reduced and the efficiency is reduced.
[0089]
Specifically, if the dielectric constant of the thermal oxide film 58 is 3.8, G1 is 0.5 μm, and the insulating film thickness t is 0.4 μm, the effective gap G ′ is 0.26 μm, and the effective gap is about 1 / 2 can be reduced. From the above-described equation (1), when converted to the electrostatic force acting between the electrodes, it becomes 3.7 times, and when trying to obtain the same electrostatic force, the voltage can be reduced to about ½.
[0090]
That is, when G1 = 0.5 μm (ε = 3.8)
When t = 0.2 μm: G2 = 0.28 μm, G ′ = 0.38 μm
When t = 0.4 μm: G2 = 0.06 μm, G ′ = 0.26 μm
It becomes.
[0091]
In order to reduce the effective gap more efficiently by forming an insulating film on the electrode surface, it is effective to use a film having a large dielectric constant. The silicon nitride film is slightly inferior to the silicon oxide film, but is suitable for reducing the effective gap more efficiently because the dielectric constant ε is 4 to 7 and larger than the silicon oxide film. Further, the effective gap can be reduced by thermally nitriding a silicon oxide film or forming SiON (oxynitride) having a large dielectric constant by using nitrogen plasma or the like.
[0092]
Next, an inkjet head according to a fifth embodiment will be described with reference to FIG. This figure is an enlarged explanatory view of the main part of the electrode part of the head.
In this head, a conductive film 59 is formed on the surface of the electrode 14. By forming a conductive film 59 on the electrode surface, the electrode interval was G1 before the film formation, whereas the post-deposition electrode interval of thickness t is G2 smaller than the film thickness. It becomes.
[0093]
As described above, since the electrode interval can be reduced by forming the conductive film, the electrostatic force can be improved and the drive voltage can be lowered. Further, in combination with the above-described method of forming an insulating film on the electrode surface, it is possible to improve the reliability and further reduce the voltage.
[0094]
Note that polysilicon or a metal film such as aluminum, nickel, or tungsten formed by sputtering or vacuum deposition can be used as the metal film to be formed. In consideration of uniformity and the like, it is preferable to form a tungsten film by a CVD method or a selective CVD method. Further, the metal film is not necessarily limited to the electrode 14 formed between the electrodes. In the case where the electrode is made of polysilicon, the electric resistance value can be reduced by adopting a configuration in which the electrode includes a metal film, and high frequency driving and multi-channel driving are facilitated.
[0095]
Next, an ink cartridge according to the present invention will be described with reference to FIG. The ink cartridge 100 is obtained by integrating the ink jet head 101 according to any of the above embodiments having the nozzle holes 101 and the like, and the ink tank 102 that supplies ink to the ink jet head 101.
[0096]
As described above, in the case of an ink tank integrated head, the cost reduction and reliability of the head immediately leads to the cost reduction and reliability of the entire ink cartridge. By reducing manufacturing defects, the yield and reliability of the ink cartridge can be improved, and the cost of the head-integrated ink cartridge can be reduced.
[0097]
  Next, the inkjet head or ink cartridge according to the present invention was mounted.As an image forming apparatus including an apparatus for discharging droplets according to the present inventionAn example of the ink jet recording apparatus will be described with reference to FIGS. FIG. 19 is a perspective explanatory view of the recording apparatus, and FIG. 20 is a side explanatory view of a mechanism portion of the recording apparatus.
[0098]
This ink jet recording apparatus includes a carriage movable in the main scanning direction inside the recording apparatus main body 111, a recording head comprising the ink jet head according to the present invention mounted on the carriage, an ink cartridge for supplying ink to the recording head, and the like. A paper feed cassette (or a paper feed tray) 114 on which a large number of sheets 113 can be stacked from the front side is detachably attached to the lower part of the apparatus main body 111. In addition, the manual feed tray 115 for manually feeding the paper 113 can be opened, the paper 113 fed from the paper feed cassette 114 or the manual feed tray 115 is taken in, and the printing mechanism unit 112 takes it as required. After the image is recorded, it is discharged to a discharge tray 116 mounted on the rear side.
[0099]
The printing mechanism 112 holds the carriage 123 slidably in the main scanning direction (the vertical direction in FIG. 20) with a main guide rod 121 and a sub guide rod 122 which are guide members horizontally mounted on left and right side plates (not shown). On this carriage 123, a head 124 comprising an inkjet head, which is a droplet discharge head according to the present invention, that discharges ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). Are arranged in a direction crossing the main scanning direction and the ink droplet discharge direction is directed downward. Also, each ink cartridge 125 for supplying each color ink to the head 124 is replaceably mounted on the carriage 123. Note that the head-integrated ink cartridge according to the present invention may be mounted.
[0100]
The ink cartridge 125 has an air port that communicates with the atmosphere upward, a supply port that supplies ink to the inkjet head below, and a porous body filled with ink inside, and the capillary force of the porous body Thus, the ink supplied to the inkjet head is maintained at a slight negative pressure.
[0101]
Further, although the heads 124 of the respective colors are used here as the recording heads, a single head having nozzles for ejecting ink droplets of the respective colors may be used.
[0102]
Here, the carriage 123 is slidably fitted on the main guide rod 121 on the rear side (downstream side in the paper conveyance direction), and is slidably mounted on the sub guide rod 122 on the front side (upstream side in the paper conveyance direction). is doing. In order to move and scan the carriage 123 in the main scanning direction, a timing belt 130 is stretched between a driving pulley 128 and a driven pulley 129 that are rotationally driven by a main scanning motor 127. The carriage 123 is reciprocally driven by forward and reverse rotation of the main scanning motor 127.
[0103]
On the other hand, in order to convey the sheet 113 set in the sheet cassette 114 to the lower side of the head 124, the sheet 113 is guided from the sheet feeding cassette 114 to the sheet feeding roller 131 and the friction pad 132. A guide member 133, a transport roller 134 that reverses and transports the fed paper 113, a transport roller 135 that is pressed against the peripheral surface of the transport roller 134, and a tip that defines the feed angle of the paper 113 from the transport roller 134 A roller 136 is provided. The transport roller 134 is rotationally driven by a sub-scanning motor 137 through a gear train.
[0104]
A printing receiving member 139 is provided as a paper guide member that guides the paper 113 fed from the transport roller 134 on the lower side of the recording head 124 corresponding to the movement range of the carriage 123 in the main scanning direction. On the downstream side of the printing receiving member 139 in the paper conveyance direction, a conveyance roller 141 and a spur 142 that are rotationally driven to send the paper 113 in the paper discharge direction are provided, and paper discharge that further feeds the paper 113 to the paper discharge tray 116. A roller 143 and a spur 144, and guide members 145 and 146 forming a paper discharge path are disposed.
[0105]
At the time of recording, the recording head 124 is driven according to the image signal while moving the carriage 123, thereby ejecting ink onto the stopped sheet 113 to record one line. Record the line. Upon receiving a recording end signal or a signal that the trailing edge of the sheet 113 reaches the recording area, the recording operation is terminated and the sheet 113 is discharged. In this case, the inkjet head according to the present invention constituting the head 124 has improved controllability of ink droplet ejection and suppressed characteristic fluctuations, so that an image with high image quality can be recorded stably.
[0106]
A recovery device 147 for recovering defective ejection of the head 124 is disposed at a position outside the recording area on the right end side in the movement direction of the carriage 123. The recovery device 147 includes a cap unit, a suction unit, and a cleaning unit. The carriage 123 is moved to the recovery device 147 side during printing standby, and the head 124 is capped by the capping unit, and the ejection port portion is kept in a wet state to prevent ejection failure due to ink drying. Further, by ejecting ink that is not related to recording during recording or the like, the ink viscosity of all the ejection ports is made constant and stable ejection performance is maintained.
[0107]
When a discharge failure occurs, the discharge port (nozzle) of the head 124 is sealed by the capping unit, and bubbles and the like are sucked out from the discharge port by the suction unit through the tube. Is removed by the cleaning means to recover the ejection failure. Further, the sucked ink is discharged to a waste ink reservoir (not shown) installed at the lower part of the main body and absorbed and held by an ink absorber inside the waste ink reservoir.
[0108]
Thus, in this ink jet recording apparatus, since the ink jet head or ink cartridge embodying the present invention is mounted, there is no ink droplet ejection failure due to vibration plate drive failure, and stable ink droplet ejection characteristics are obtained, Image quality is improved. In addition, since a head that can be driven at a low voltage is mounted, the power consumption of the entire inkjet recording apparatus can be reduced.
[0109]
Next, the micropump according to the present invention will be described with reference to FIG. In addition, the figure is principal part cross-sectional explanatory drawing of the micropump.
This micro pump has a laminated structure in which a flow path substrate 201 and a protective substrate 202 are overlapped and joined. The flow path substrate 201 forms a flow path 203 through which a fluid flows, and one wall surface of the flow path 203 is formed. A deformable movable plate 204 (corresponding to the vibration plate of the head) to be formed is provided, and a portion of the movable plate 204 that is not bonded and fixed to the protective substrate 202 is a movable portion 205.
[0110]
A plurality of electrodes 207 (having the same configuration as the electrodes 14 of the head according to the second embodiment) are arranged on the movable portion 205 on the outer surface side through the insulating film 206 in the same manner as the ink jet head. Is provided. The protective substrate 202 has a function similar to that of the second substrate 2 of the head, and has a recess 208 in which the electrode 207 is disposed. Here, the protective substrate 202 has a recess 208 formed by providing a spacer portion 209 on a flat plate substrate.
[0111]
The operation principle of this micropump will be described. Since the electrostatic attraction force is generated between the electrodes 207 by applying a pulse potential to every other plurality of electrodes 207 as described above, the movable portion 205 is formed in the flow path 203. Deforms to the side. Here, by sequentially driving the movable portion 205 from the right side in the figure, the fluid in the flow path 203 flows in the direction of the arrow, and the fluid can be transported.
[0112]
In this embodiment, an example in which a plurality of movable parts are provided is shown, but one movable part may be provided. Further, in order to increase the transportation efficiency, one or more valves such as a check valve can be provided between the movable parts.
[0113]
Next, an embodiment of an optical device according to the present invention will be described with reference to FIG. This figure is a schematic configuration diagram of the device.
In this optical device, a deformable mirror 301 and a protective substrate 302 are overlapped and bonded, and a portion of the mirror 301 that is not bonded and fixed to the protective substrate 302 is a movable portion 305. The movable portion 305 is provided with a plurality of electrodes 307 (having the same configuration as the electrode 14 of the head of the second embodiment) on the outer surface side through an insulating film 306 at a predetermined interval. The protective substrate 302 has a function similar to that of the second substrate 2 of the head, and has a recess 308 for disposing the electrode 307. Here, the protective substrate 302 forms a recess 308 by providing a spacer portion 309 on a flat plate substrate. The surface of the mirror 301 is preferably formed with a dielectric multilayer film or a metal film in order to increase the reflectance.
[0114]
The principle of this optical device will be described. An electrostatic attraction force is generated between the electrodes 307 by applying a pulse potential to every other electrode 307 provided on the movable part 305 of the mirror 301. 305 is deformed into a convex shape to form a convex mirror. Therefore, when the light from the light source 310 is applied to the mirror 301 via the lens 311, when the mirror 301 is not driven, the light is reflected at the same angle as the incident angle, but when the mirror 301 is driven to the movable part 305. Since the movable part 305 becomes a convex mirror, the reflected light becomes divergent light. Thereby, an optical modulation device can be realized.
[0115]
Therefore, an example in which this optical device is applied will be described with reference to FIGS. In this example, the optical devices described above are two-dimensionally arranged, and the movable part 305 of each mirror is driven independently. Although a 4 × 4 array is shown here, it is possible to arrange more than this. In addition, the electrode 307 is separated in a lattice shape on the surface of the movable portion 305 (the electrode 14 can also be separated in a lattice shape as in the case of the electrode 305 in the embodiment of the droplet discharge head). .
[0116]
Therefore, similarly to FIG. 22 described above, the light from the light source 310 is irradiated to the mirror 301 via the lens 311, and the light incident on the portion where the mirror 301 is not driven enters the projection lens 312. On the other hand, a portion where the movable portion 305 of the mirror 301 is deformed by applying a voltage to the electrode 307 becomes a convex mirror, so that light diverges and hardly enters the projection lens 312. The light incident on the projection lens 312 is projected on a screen (not shown) or the like, and an image can be displayed on the screen.
[0117]
In the embodiments of these micropumps and optical devices, the actuator has the same configuration as the inkjet head according to the first embodiment, but the actuator has the same configuration as the inkjet head according to the second and subsequent embodiments. You can also
[0118]
  In the above embodiment, the example in which the ink jet head is applied as a liquid droplet ejecting head has been described. The present invention can also be applied to other droplet discharge heads such as a droplet discharge head that discharges the sample as droplets. In addition to micropumps and optical devices (light modulation devices), microactuators can also be applied to microswitches (microrelays), multi-optical lens actuators (optical switches), microflowmeters, pressure sensors, etc. it can. Moreover, although the example which provided the electrode in the single side | surface of a diaphragm is demonstrated, it can also provide in both surfaces.Further, as described above, the present invention can also be applied to an image forming apparatus such as a printer, a facsimile machine, and a copying apparatus, and an apparatus that discharges droplets.
[0119]
【The invention's effect】
  As described above, according to the droplet discharge head of the present invention, the diaphragmOn the surfaceA plurality of electrodes composed of electrically conductive structures that are electrically isolated from each otherThe plurality of electrodes are arranged side by side along the plane of the diaphragm, and the plurality of electrodes are fixed ends with one end fixed to the plane of the diaphragm, and the free end with the other end not fixed Furthermore, the electrode has a shape of a cross section along the alignment direction, the fixed end side is narrow, the free end side is wide,The interval between the plurality of electrodes is wider on the fixed end side than on the free end side, and a diaphragm is generated by generating an electrostatic force between the electrodes.ButDeformationYouRuConfiguredTherefore, it is possible to obtain a head that is low in cost, has high droplet ejection efficiency, and can perform high-quality printing, and can increase the displacement efficiency of the diaphragm, and can be driven at a low voltage, and the mechanical strength of the electrode. When the electrode is formed of a deposited film while maintaining the thickness of the electrode, it can be formed without greatly increasing the thickness of the deposition, and the height of the electrode can be increased while suppressing an increase in process cost. Can be made.
[0120]
Here, since the electrode contains polysilicon, it is possible to easily form a structure that acts as an electrode having conductivity, and to improve controllability and anisotropy (verticality) when the electrode is formed by etching. Thus, the electrodes can be formed with high accuracy at a narrow interval, and a large electrostatic force can be generated. By including n-type or p-type impurity atoms in the polysilicon, the resistance can be reduced, and more stable high-frequency driving and multi-channel driving can be performed. In addition, even if the electrode contains a metal, the resistance can be reduced, and more stable high-frequency driving and multi-channel driving can be performed.
[0121]
  further,A structure in which a sacrificial layer that defines at least a part of the distance between the electrodes is formed on the surface of the diaphragm and the electrodes are formed, and the sacrificial layer is etched away to form a space between the electrodes.High-aspect (narrow and deep) grooves that are difficult to etch can be formed, and the electrode thickness is large (high) and the electrode spacing can be narrowed to generate a large electrostatic force. Can do. In this case, by providing an opening for sacrificial layer etching in the electrode, an electrode having a narrow electrode interval can be easily formed with a high yield.
[0122]
In addition, by forming an insulating film on the electrode surface, it is possible to reduce malfunctions due to short-circuiting between electrodes, and the insulating film can reduce the effective electrode spacing and generate a large electrostatic force. Can do. By using this insulating film as a silicon oxide film, a high breakdown voltage electrode can be easily formed with good controllability, and by using a silicon nitride film as the insulating film, the effective electrode spacing can be reduced. A large electrostatic force can be generated. Furthermore, by electrically separating the diaphragm and the electrode, the voltage applied to the electrode does not leak to the diaphragm side and cannot be operated, so that the voltage can be efficiently applied to the electrode.
[0123]
According to the ink cartridge of the present invention, the droplet discharge head according to the present invention that discharges ink droplets and the ink tank that supplies ink to the droplet discharge head are integrated, so that the droplet discharge efficiency is low in cost. A high-quality head capable of high-quality printing can be integrated, manufacturing defects can be reduced, and cost can be reduced.
[0124]
  According to the ink jet recording apparatus according to the present invention, since the ink jet head for ejecting ink droplets is the liquid droplet ejecting head according to the present invention or the ink cartridge according to the present invention, high quality recording can be performed. Cost reduction can be achieved.According to the image forming apparatus of the present invention, since the liquid droplet ejection head according to the present invention is provided, high image quality recording can be performed. According to the apparatus for ejecting droplets according to the present invention, since the droplet ejection head according to the present invention is provided, the droplet ejection efficiency is improved.
[0125]
  According to the microactuator according to the present invention, a plurality of electrodes made of a conductive structure electrically isolated from each other are provided on the surface of the movable part.Moving partsThe plurality of electrodes are provided as fixed ends with one end fixed to the surface of the movable part, and the other ends are free ends that are not fixed. Furthermore, the electrode has a cross-sectional shape along the alignment direction, the fixed end side is narrow, the free end side is wide, and the interval between the plurality of electrodes is wider at the fixed end side than the free end side. Since the movable part is deformed by generating an electrostatic force in between, the electrode can be deposited with a deposited film at low cost, with improved operating efficiency and low voltage drive, while maintaining the mechanical strength of the electrode. In the case of forming, it can be formed without making the thickness of the deposit very large, and the height of the electrode can be increased while suppressing an increase in process cost, and the movable part can be displaced greatly more efficiently.
[0126]
According to the micropump according to the present invention, the micropump transports liquid by deformation of the movable part and includes the microactuator according to the present invention, so that the operation efficiency is high, the size is small, and the power consumption is reduced. In addition, the cost can be reduced.
[0127]
According to the optical device of the present invention, the optical device changes the light reflection direction by the displacement of the mirror formed on the movable part, and includes the microactuator according to the present invention, so it is small in size and has low power consumption. As well as cost reduction.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of an inkjet head according to a first embodiment of a droplet discharge head of the present invention.
FIG. 2 is a cross-sectional explanatory view of the head in the longitudinal direction of the diaphragm.
FIG. 3 is an enlarged cross-sectional explanatory view of the main part of the head in the short direction of the diaphragm.
FIG. 4 is an enlarged explanatory view of an electrode portion of the head.
FIG. 5 is an explanatory plan view for explaining an electrode arrangement pattern of the head.
FIG. 6 is an enlarged sectional explanatory view of a main part for explaining the operation of the head.
FIG. 7 is an explanatory diagram for explaining an example of the manufacturing process of the head
FIG. 8 is an explanatory plan view of a process corresponding to FIG. 7D for explaining the inkjet head according to the second embodiment;
9 is a cross-sectional explanatory view taken along line AA in FIG. 8 corresponding to FIGS. 7 (d) and 7 (e) for explaining the manufacturing process of the head.
FIG. 10 is a cross-sectional explanatory view illustrating the inkjet head according to the third embodiment together with the manufacturing process thereof.
11 is an explanatory diagram for explaining a process following FIG.
FIG. 12 is a cross-sectional explanatory view illustrating another example of the step of FIG.
FIG. 13 is an explanatory cross-sectional view illustrating the inkjet head according to the third embodiment together with the manufacturing process thereof.
FIG. 14 is an enlarged explanatory view of an electrode portion for explaining the operation of the silicon oxide film of the head.
FIG. 15 is a cross-sectional explanatory view illustrating another example of the embodiment
FIG. 16 is an enlarged explanatory view of an electrode portion for explaining the operation of the silicon oxide film of another example.
FIG. 17 is an enlarged explanatory view of an electrode portion for explaining the ink jet head according to the fourth embodiment.
FIG. 18 is an explanatory perspective view for explaining the ink cartridge according to the present invention.
FIG. 19 is a perspective explanatory view illustrating an example of an ink jet recording apparatus according to the invention.
FIG. 20 is an explanatory diagram of a mechanism unit of the recording apparatus.
FIG. 21 is an explanatory cross-sectional view illustrating an embodiment of a micropump according to the present invention.
FIG. 22 is an explanatory cross-sectional view illustrating an embodiment of an optical device according to the present invention.
FIG. 23 is an explanatory perspective view illustrating an example of a light modulation device using the optical device.
FIG. 24 is a perspective view illustrating a main part of the optical modulation device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... 1st board | substrate, 2 ... 2nd board | substrate, 3 ... Nozzle plate, 4 ... Nozzle hole, 6 ... Discharge chamber, 7 ... Fluid resistance part, 8 ... Common liquid chamber, 10 ... Vibrating plate, 14 ... Electrode, 100 ... Ink cartridge, 201 ... channel substrate, 203 ... channel, 205 ... movable part, 207 ... electrode, 301 ... mirror, 305 ... movable part, 307 ... electrode.

Claims (16)

A single or a plurality of nozzle holes for discharging liquid droplets, a discharge chamber communicating with each of the nozzle holes, and a vibration plate constituting at least one wall of the discharge chamber, and deforming the vibration plate In a droplet discharge head that discharges droplets by applying pressure to the liquid,
On the surface of the diaphragm, a plurality of electrodes made of electrically conductive structures that are electrically insulated and separated from each other are provided side by side along the surface of the diaphragm.
The plurality of electrodes have a fixed end portion whose one end is fixed to the surface of the diaphragm, and a free end portion whose other end portion is not fixed,
Further, the electrode has a cross-sectional shape along the alignment direction, the fixed end side is narrow, the free end side is wide,
The interval between the plurality of electrodes is wider on the fixed end side than on the free end side,
The liquid droplet ejection head, wherein the diaphragm is deformed by generating an electrostatic force between the electrodes.   2. The liquid droplet ejection head according to claim 1, wherein the electrode includes polysilicon.   3. The droplet discharge head according to claim 2, wherein the polysilicon contains n-type or p-type impurity atoms.   4. The liquid droplet ejection head according to claim 1, wherein the electrode contains a metal.   5. The droplet discharge head according to claim 1, wherein a sacrificial layer that defines at least a part of an interval between the electrodes is formed on the surface of the vibration plate, and the electrodes are formed. A droplet discharge head, wherein the gap is formed by etching away the sacrificial layer.   6. The droplet discharge head according to claim 1, wherein an opening is formed in the electrode.   The liquid droplet ejection head according to claim 1, wherein an insulating film is formed on the surface of the electrode.   8. The liquid droplet ejection head according to claim 7, wherein the insulating film includes a silicon oxide film or a silicon nitride film.   9. The droplet discharge head according to claim 1, wherein the vibration plate and the electrode are electrically separated from each other.   10. A droplet discharge head according to claim 1, wherein a droplet discharge head for discharging ink droplets and an ink cartridge in which an ink tank for supplying ink to the droplet discharge head is integrated. An ink cartridge which is a head.   An inkjet recording apparatus equipped with an inkjet head for ejecting ink droplets, wherein the inkjet head is the droplet ejection head according to claim 1 or the ink cartridge according to claim 10. Inkjet recording device. A microactuator that deforms a plate-shaped movable part,
A plurality of electrodes made of electrically conductive structures that are electrically insulated and separated from each other are provided on the surface of the movable part , arranged side by side along the surface of the movable part ,
The plurality of electrodes has a fixed end fixed at one end to the surface of the movable part, and a free end not fixed at the other end.
Further, the electrode has a cross-sectional shape along the alignment direction, the fixed end side is narrow, the free end side is wide,
The interval between the plurality of electrodes is wider on the fixed end side than on the free end side,
The microactuator is characterized in that the movable part is deformed by generating an electrostatic force between the electrodes.   A micropump for transporting a liquid by deformation of a movable part, comprising the microactuator according to claim 12.   13. An optical device that changes the direction of light reflection by displacement of a mirror formed on a movable part, comprising the microactuator according to claim 12.   An image forming apparatus comprising a droplet discharge head for forming an image, wherein the droplet discharge head is the droplet discharge head according to any one of claims 1 to 9.   An apparatus for ejecting droplets from a droplet ejection head, wherein the droplet ejection head is the droplet ejection head according to any one of claims 1 to 9.

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