JP2004087450A

JP2004087450A - Electron emitting element and field emission display using the same

Info

Publication number: JP2004087450A
Application number: JP2002319761A
Authority: JP
Inventors: Yukihisa Takeuchi; 武内　幸久; Tsutomu Nanataki; 七瀧　　努; Iwao Owada; 大和田　　巌; Tomoya Horiuchi; 堀内　智哉
Original assignee: NGK Insulators Ltd
Current assignee: NGK Insulators Ltd
Priority date: 2001-12-20
Filing date: 2002-11-01
Publication date: 2004-03-18
Anticipated expiration: 2022-11-01
Also published as: EP1329928A3; EP1329928A2; JP3848237B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electron emitting element having the favorable linearity of emitted electrons and a field emission display using the element. <P>SOLUTION: The electron emitting element has an electric field applying part 1 formed by a dielectric, a drive electrode 2 as a first electrode formed on one surface of the field applying part 1 and a common electrode 3 as a second electrode formed on the same surface as the first electrode and forming a slit together with the drive electrode 2 and is formed on a substrate 4. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】本発明は、電子放出素子及びそれを用いたフィールドエミッションディスプレイに関するものである。
【０００２】
【従来の技術】このような電子放出素子は、駆動用の電極及び接地用の電極を有し、フィールドエミッションディスプレイ（ＦＥＤ）やバックライトのような種々のアプリケーションに適用されている（例えば、特許文献１〜５及び非特許文献１〜３参照）。ＦＥＤに適用する場合、複数の電子放出素子を２次元的に配列し、これら電子放出素子に対する複数の蛍光体が、所定の間隔を以ってそれぞれ配置されている。
【０００３】
【発明が解決しようとする課題】しかしながら、従来の電子放出素子の直進性、すなわち、放出された電子が所定の対象（例えば蛍光体）に直進する程度が良好でなく、放出された電子によって所望の電流密度を確保するためには、比較的高い電圧を電子放出素子に印加する必要がある。
【０００４】
【特許文献１】特開平１−３１１，５３３号公報（第３頁、第１図）
【特許文献２】特開平７−１４７，１３１号公報（第３頁、図８及び図９）
【特許文献３】特開２０００−２８５，８０１号公報（第５頁、図３）
【特許文献４】特公昭４６−２０，９４４号公報（第１頁、第２図）
【特許文献５】特公昭４４−２６，１２５号公報（第１頁、第２図）
【非特許文献１】安岡・石井、「強誘電体陰極を用いたパルス電子源」、応用物理　第６８巻　第５号　ｐ．５４６〜５５０（１９９９）
【非特許文献２】Ｖ．Ｆ．Ｐｕｃｈｋａｒｅｖ，　Ｇ．Ａ．Ｍｅｓｙａｔｓ，　Ｏｎ　ｔｈｅ　ｍｅｃｈａｎｉｓｍ　ｏｆ　ｅｍｉｓｓｉｏｎｆｒｏｍ　ｔｈｅ　ｆｅｒｒｏｅｌｅｃｔｒｉｃ　ｃｅｒａｍｉｃ　ｃａｔｈｏｄｅ，　Ｊ．　Ａｐｐｌ．　Ｐｈｙｓ．，　Ｖｏｌ．７８，　Ｎｏ．９　Ｎｏｖｅｍｂｅｒ　１９９５，　ｐ．５６３３−５６３７
【非特許文献３】Ｈ．Ｒｉｅｇｅ，　Ｅｌｅｃｔｒｏｎ　ｅｍｉｓｓｉｏｎ　ｆｅｒｒｏｅｌｅｃｔｒｉｃｓ−ａ　ｒｅｖｉｅｗ，　Ｎｕｃｌ．　Ｉｎｓｔｒ．　Ａｎｄ　Ｍｅｔｈ．　Ａ３４０，　ｐ．８０−８９　（１９９４）
【０００５】また、従来の電子放出素子をＦＥＤに適用した場合、直進性が良好でないためにクロストークが比較的に大きくなる、すなわち、放出された電子が、対応する蛍光体に隣接する蛍光体に入射するおそれが高くなる。その結果、蛍光体のピッチを狭くするのが困難となり、隣接する蛍光体に電子が入射されるのを防止するためにグリッドを設ける必要がある。
【０００６】本発明の目的は、良好な放出電子の直進性を有する電子放出素子及びそれを用いたフィールドエミッションディスプレイを提供することである。
【０００７】本発明の他の目的は、比較的低真空で、非常に低い駆動電圧にて高い電流密度を有する電子放出を実現する電子放出素子及びそれを用いたフィールドエミッションディスプレイを提供することである。
【０００８】
【課題を解決するための手段】本発明による電子放出素子は、
誘電体によって構成された電界印加部と、
この電界印加部の一方の面に形成された第１電極と、
前記電界印加部の一方の面に形成され、前記第１電極とともにスリットを形成する第２電極とを有することを特徴とするものである。
【０００９】本発明によれば、第１又は第２電極にパルス電圧を印加すると、電界印加部から電子が放出される。電界印加部を誘電体によって構成することによって、従来の電子放出素子では達成できない良好な直進性を得ることができる。その結果、所望の電流密度を確保するために電子放出素子に印加される電圧が従来に比べて著しく低くなり、消費エネルギーが大幅に低減される。なお、第１及び第２電極を厚膜印刷によって電界印加部に形成することができるので、本発明による電子放出素子は、耐久性及びコスト低減の観点からも好ましい。
【００１０】電子放出素子に印加される電圧を更に低減させるために、前記第１電極、第２電極及びスリットに設けられた導電性コーティング部を更に有するのが好ましい。この場合、導電性コーティング部によって、電子及び／又はイオンの衝突や発熱による第１及び第２電極の損傷のおそれが著しく軽減する。
【００１１】更に好適には、前記第１電極に設けられた第１導電性コーティング部と、
その第１コーティング部とは非接触状態で前記第２電極に設けられた第２導電性コーティング部とを更に有する。この場合、第１電極と第２電極との間の等価回路に抵抗が含まれなくなるので、直流カット用のコンデンサが不要となり、高電圧での駆動の必要がなくなるので、電子放出素子に印加される電圧を一層低減することができる。この場合も、第１及び第２導電性コーティング部によって、電子及び／又はイオンの衝突や発熱による第１及び第２電極の損傷のおそれが著しく軽減する。
【００１２】前記第１及び第２導電性コーティング部に比べて高い抵抗を有するとともに前記第１及び第２導電性コーティング部に電気的に接触する高抵抗部を、前記スリットに設けてもよい。この場合、電子放出素子に電圧が印加されると、高抵抗部の電圧は、第１及び第２導電性コーティング部の電圧より高くなり、高抵抗部すなわちスリットにおける電界の集中度が向上する。その結果、高抵抗部を有しない場合に比べて低い印加電圧で電子を放出することができ、消費電力が低減し、かつ、回路の小型化及び高電圧対応部品の省略によるコストダウンを図ることができる。
【００１３】電子の放出を良好に行うために、前記第１及び第２電極に対して所定の間隔を以って配置した第３電極を更に有し、前記第１及び第２電極と前記第３電極との間の空間を真空とするのが好ましい。
【００１４】本発明による他の電子放出素子は、
圧電材料、電歪材料及び反強誘電材料のうちの少なくとも１種類によって構成された電界印加部と、
この電界印加部の一方の面に形成された第１電極と、
前記電界印加部の一方の面に形成され、前記第１電極とともにスリットを形成する第２電極とを有することを特徴とするものである。
【００１５】本発明によれば、第１又は第２電極にパルス電圧を印加した際に、電界印加部が、アクチュエータとしても機能し、屈曲変位させるようにしても良い。その結果、電子放出素子の直進性が更に向上する。
【００１６】電子放出素子に印加される電圧を更に低減させるために、前記第１電極、第２電極及びスリットに設けられた導電性コーティング部を更に有するのが好ましい。この場合、導電性コーティングによって、電子及び／又はイオンの衝突や発熱による第１及び第２電極の損傷のおそれが著しく軽減する。
【００１７】更に好適には、前記第１電極に設けられた第１導電性コーティング部と、
その第１コーティング部とは非接触状態で前記第２電極に設けられた第２導電性コーティング部とを更に有する。この場合、第１電極と第２電極との間の等価回路に抵抗が含まれなくなるので、直流カット用のコンデンサが不要となり、高電圧での駆動の必要がなくなるので、電子放出素子に印加される電圧を一層低減することができる。この場合も、第１及び第２導電性コーティング部によって、電子及び／又はイオンの衝突や発熱による第１及び第２電極の損傷のおそれが著しく軽減する。
【００１８】前記第１及び第２導電性コーティング部に比べて高い抵抗を有するとともに前記第１及び第２導電性コーティング部に電気的に接触する高抵抗部を、前記スリットに設けてもよい。この場合、電子放出素子に電圧が印加されると、高抵抗部の電圧は、第１及び第２導電性コーティング部の電圧より高くなり、高抵抗部すなわちスリットにおける電界の集中度が向上する。その結果、高抵抗部を有しない場合に比べて低い印加電圧で電子を放出することができ、消費電力が低減し、かつ、回路の小型化及び高電圧対応部品の省略によるコストダウンを図ることができる。
【００１９】この場合も、電子の放出を良好に行うために、前記第１及び第２電極に対して所定の間隔を以って配置した第３電極を更に有し、前記第１及び第２電極と前記第３電極との間の空間を真空とするのが好ましい。この場合も、電界印加部がアクチュエータとしても機能させるようにしても良い。この結果、その変位動作によって、放出電子量を制御することができる。
【００２０】好適には、前記第３電極に直流のオフセット電圧を印加する電圧源と、この電圧源と前記第３電極との間に直列配置した抵抗とを更に有する。これによって、所望の電流密度を容易に達成することができるとともに、第３電極と第１及び第２電極との間の短絡が防止される。
【００２１】例えば、前記第１電極にパルス電圧が印加されるとともに、前記第２電極に直流のオフセット電圧が印加される。
【００２２】好適には、前記第１電極と電圧信号源との間に直列配置したコンデンサを更に有する。これによって、コンデンサを充填するまでの時間のみ第１電極と第２電極との間に電圧を印加することができ、その結果、第１及び第２電極の短絡による破損が防止される。
【００２３】前記電界印加部の他方の面に形成され、前記第１電極に対応する第４電極を更に有する場合、第１電極と第４電極との間の電界印加部がコンデンサの機能を果たすので、第１及び第２電極の短絡による破損が防止される。この場合、例えば、前記第４電極にパルス電圧が印加されるとともに、前記第２電極に直流のオフセット電圧が印加される。
【００２４】前記第２電極と直流オフセット電圧源との間に直列配置した抵抗を更に有してもよい。この場合、第１電極から第２電極に放電して流れる電流が抵抗によって抑制され、第１及び第２電極の短絡による破損が防止される。
【００２５】印加電圧の大幅な低減を図るために、前記電界印加部の比誘電率を１０００以上とし、及び／又は、前記スリットの幅を５００μｍ以下とするのが好ましい。
【００２６】電子の放出を良好に行うために、前記第１電極と第２電極のうちの少なくとも一方が、鋭角を成す角部を有し、及び／又は、前記第１電極及び第２電極がカーボンナノチューブ、すなわち、六炭素環構造を有するカーボン材料を含む粒子又は粒子の凝集体を有するのが好ましい。
【００２７】本発明によるフィールドエミッションディスプレイは、
２次元的に配列された複数の電子放出素子と、
これら電子放出素子に対してそれぞれ所定の間隔を以って配置した複数の蛍光体とを具え、
前記電子放出素子の各々が、
誘電体によって構成された電界印加部と、
この電界印加部の一方の面に形成された第１電極と、
前記電界印加部の一方の面に形成され、前記第１電極とともにスリットを形成する第２電極とを有することを特徴とするものである。
【００２８】本発明によれば、電子放出素子の直進性が優れているので、従来の電子放出素子を有する場合に比べてクロストークが小さくなり、蛍光体のピッチを狭くすることができ、かつ、隣接する蛍光体に電子が入射されるのを防止するためにグリッドを設ける必要がなくなる。その結果、本発明によるフィールドエミッションディスプレイは、解像度の向上、装置の小型化及びコスト低減の観点から好ましい。なお、フィールドエミッションディスプレイ内部の真空度が比較的低い場合でも電子の放出が可能であるため、蛍光体励起などの原因で内部の真空度が低下しても電子の放出を維持することができる。なお、従来のフィールドエミッションディスプレイでは、このような真空度の低下に対して、電子放出を維持するためのマージンとして真空空間を比較的大きく確保する必要があり、ディスプレイの薄型化が困難であった。それに対して、本発明では、真空度の低下に対して電子の放出を維持するために真空空間を予め大きく確保する必要がないので、ディスプレイの薄型化が可能となる。
【００２９】電子放出素子に印加される電圧を更に低減させるために、前記第１電極、第２電極及びスリットに導電性コーティングを施するが好ましい。この場合、導電性コーティングによって、電子及び／又はイオンの衝突や発熱による第１及び第２電極の損傷のおそれが著しく軽減する。
【００３０】更に好適には、前記第１電極に設けられた第１導電性コーティング部と、
その第１コーティング部とは非接触状態で前記第２電極に設けられた第２導電性コーティング部とを更に有する。この場合、第１電極と第２電極との間の等価回路に抵抗が含まれなくなるので、直流カット用のコンデンサが不要となり、高電圧での駆動の必要がなくなるので、電子放出素子に印加される電圧を一層低減することができる。この場合も、第１及び第２導電性コーティング部によって、電子及び／又はイオンの衝突や発熱による第１及び第２電極の損傷のおそれが著しく軽減する。
【００３１】前記第１及び第２導電性コーティング部に比べて高い抵抗を有するとともに前記第１及び第２導電性コーティング部に電気的に接触する高抵抗部を、前記スリットに設けてもよい。この場合、電子放出素子に電圧が印加されると、高抵抗部の電圧は、第１及び第２導電性コーティング部の電圧より高くなり、高抵抗部すなわちスリットにおける電界の集中度が向上する。その結果、高抵抗部を有しない場合に比べて低い印加電圧で電子を放出することができ、消費電力が低減し、かつ、回路の小型化及び高電圧対応部品の省略によるコストダウンを図ることができる。
【００３２】電子の放出を良好に行うために、前記第１及び第２電極に対して所定の間隔を以って配置した第３電極を更に有し、前記第１及び第２電極と前記第３電極との間の空間を真空とするのが好ましい。
【００３３】本発明による他のフィールドエミッションディスプレイは、
２次元的に配列された複数の電子放出素子と、
これら電子放出素子に対してそれぞれ所定の間隔を以って配置した複数の蛍光体とを具え、
前記電子放出素子の各々が、
圧電材料、電歪材料及び反強誘電材料のうちの少なくとも１種類によって構成された電界印加部と、
この電界印加部の一方の面に形成された第１電極と、
前記電界印加部の一方の面に形成され、前記第１電極とともにスリットを形成する第２電極とを有することを特徴とするものである。
【００３４】本発明によれば、電子放出素子の直進性が更に良好になるので、本発明によるフィールドエミッションディスプレイは、小型化及びコスト低減の観点から更に好ましくなる。
【００３５】電子放出素子に印加される電圧を更に低減させるために、前記第１電極、第２電極及びスリットに導電性コーティングを施するが好ましい。この場合、導電性コーティングによって、電子及び／又はイオンの衝突や発熱による第１及び第２電極の損傷のおそれが著しく軽減する。
【００３６】更に好適には、前記第１電極に設けられた第１導電性コーティング部と、
その第１コーティング部とは非接触状態で前記第２電極に設けられた第２導電性コーティング部とを更に有する。この場合、第１電極と第２電極との間の等価回路に抵抗が含まれなくなるので、直流カット用のコンデンサが不要となり、高電圧での駆動の必要がなくなるので、電子放出素子に印加される電圧を一層低減することができる。この場合も、第１及び第２導電性コーティング部によって、電子及び／又はイオンの衝突や発熱による第１及び第２電極の損傷のおそれが著しく軽減する。
【００３７】前記第１及び第２導電性コーティング部に比べて高い抵抗を有するとともに前記第１及び第２導電性コーティング部に電気的に接触する高抵抗部を、前記スリットに設けてもよい。この場合、電子放出素子に電圧が印加されると、高抵抗部の電圧は、第１及び第２導電性コーティング部の電圧より高くなり、高抵抗部すなわちスリットにおける電界の集中度が向上する。その結果、高抵抗部を有しない場合に比べて低い印加電圧で電子を放出することができ、消費電力が低減し、かつ、回路の小型化及び高電圧対応部品の省略によるコストダウンを図ることができる。
【００３８】この場合も、電子の放出を良好に行うために、前記第１及び第２電極に対して所定の間隔を以って配置した第３電極を更に有し、前記第１及び第２電極と前記第３電極との間の空間を真空とするのが好ましい。この場合も、電界印加部がアクチュエータとしても機能させるようにしても良い。この結果、その変位動作によって、放出電子量を制御することができる。
【００３９】好適には、前記第３電極に直流のオフセット電圧を印加する電圧源と、この電圧源と前記第３電極との間に直列配置した抵抗とを更に有する。これによって、所望の電流密度すなわち蛍光体の発光量を容易に達成することができるとともに、第３電極と第１及び第２電極との間の短絡が防止される。
【００４０】例えば、前記第１電極にパルス電圧が印加されるとともに、前記第２電極に直流のオフセット電圧が印加される。
【００４１】好適には、前記第１電極と電圧信号源との間に直列配置したコンデンサを更に有する。これによって、第１及び第２電極の短絡による破損が防止される。
【００４２】前記電界印加部の他方の面に形成され、前記第１電極に対応する第４電極を更に有する場合も、第１及び第２電極の短絡による破損が防止される。この場合、例えば、前記第４電極にパルス電圧が印加されるとともに、前記第２電極に直流のオフセット電圧が印加される。
【００４３】前記第２電極と直流オフセット電圧源との間に直列配置した抵抗を更に有する場合も、第１及び第２電極の短絡による破損が防止される。
【００４４】印加電圧の大幅な低減を図るために、前記電界印加部の比誘電率を１０００以上とし、及び／又は、前記スリットの幅を５００μｍ以下とするのが好ましい。
【００４５】電子の放出を良好に行うために、前記第１電極と第２電極のうちの少なくとも一方が、鋭角を成す角部を有し、及び／又は、前記第１電極及び第２電極がカーボンナノチューブを有するのが好ましい。
【００４６】本発明によるフィールドエミッションディスプレイは、２次元的に配列された複数の電子放出素子を一体に形成した基板を更に具える。
【００４７】
【発明の実施の形態】本発明による電子放出素子及びそれを用いたフィールドエミッションディスプレイの実施の形態を、図面を参照して詳細に説明する。
【００４８】図１Ａは、本発明による電子放出素子の第１の実施の形態の上面図であり、図１Ｂは、そのＩ−Ｉ断面図である。この電子放出素子は、誘電体によって構成された電界印加部１と、その一方の面に形成された第１電極としての駆動電極２と、それと同一面に形成され、駆動電極２とともにスリットを形成する第２電極としてのコモン電極３とを有し、基板４の上に形成される。好適には、この電子放出素子は、放出された電子を良好に捕獲するために、電界印加部１の一方の面に対して所定の間隔を配置した第３電極としての電子捕獲電極５を更に有し、これらの間の空間を真空状態に保持する。また、駆動電極２及びコモン電極３の短絡による破損を防止するために、駆動電極２と図示しない電圧信号源との間に、図示しないコンデンサを直列配置し、及び／又は、コモン電極３と図示しない直流オフセット電圧源との間に、図示しない抵抗を直列配置する。なお、図１Ａにおいては、明瞭のために電子捕獲電極５を省略している。
【００４９】電界印加部１を構成する誘電体として、好適には、比誘電率が比較的高い、例えば１０００以上の誘電体を採用する。このような誘電体としては、チタン酸バリウムの他に、ジルコン酸鉛、マクネシウムニオブ酸鉛、ニッケルニオブ酸鉛、亜鉛ニオブ酸鉛、マンガンニオブ酸鉛、マグネシウムタンタル酸鉛、ニッケルタンタル酸鉛、アンチモンスズ酸鉛、チタン酸鉛、チタン酸バリウム、マグネシウムタングステン酸鉛、コバルトニオブ酸鉛等又はこれらの任意の組合せを含有するセラミックスや、主成分がこれらの化合物を５０重量％以上含有するものや、前記セラミックスに対して更にランタン、カルシウム、ストロンチウム、モリブデン、タングステン、バリウム、ニオブ、亜鉛、ニッケル、マンガン等の酸化物若しくはこれらのいずれかの組合せ又は他の化合物を適切に添加したもの等を挙げることができる。例えば、マグネシウムニオブ酸鉛（ＰＭＮ）とチタン酸鉛（ＰＴ）の２成分系ｎＰＭＮ−ｍＰＴ（ｎ，ｍをモル数比とする。）においては、ＰＭＮのモル数比を大きくすると、キュリー点が下げられて、室温での比誘電率を大きくすることができる。特に、ｎ＝０．８５−１．０，ｍ＝１．０−ｎで比誘電率３０００以上となり好ましい。例えば、ｎ＝０．９１，ｍ＝０．０９で室温の比誘電率１５０００，ｎ＝０．９５，ｍ＝０．０５で室温の比誘電率２００００が得られる。次に、マグネシウムニオブ酸鉛（ＰＭＮ）、チタン酸鉛（ＰＴ）、ジルコン酸鉛（ＰＺ）の３成分系では、ＰＭＮのモル数比を大きくする他に、正方晶と擬立方晶又は正方晶と菱面体晶のモルフォトロピック相境界（ＭＰＢ：Ｍｏｒｐｈｏｔｒｏｐｉｃ　Ｐｈａｓｅ　Ｂｏｕｎｄａｒｙ）付近の組成とすることが比誘電率を大きくするのに好ましい。例えば、ＰＭＮ：ＰＴ：ＰＺ＝０．３７５：０．３７５：０．２５にて比誘電率５５００，ＰＭＮ：ＰＴ：ＰＺ＝０．５：０．３７５：０．１２５にて比誘電率４５００となり、特に好ましい。さらに、絶縁性が確保できる範囲内でこれらの誘電体に白金のような金属を混入して、誘電率を向上させるのが好ましい。この場合、例えば、誘電体に白金を重量比で２０％混入させる。
【００５０】本実施の形態では、駆動電極２は、鋭角を成す角部を有する。駆動電極２には、図示しない電源からパルス電圧が印加され、主に角部から電子が放出される。なお、電子の放出を良好に行うために、駆動電極２とコモン電極３との間のスリットの幅Δを、好適には５００μｍ以下にする。駆動電極２を、高温酸化雰囲気に対して耐性を有する導体、例えば金属単体、合金、絶縁性セラミックスと金属単体との混合物、絶縁性セラミックスと合金との混合物等によって構成し、好適には、白金、パラジウム、ロジウム、モリブデン等の高融点貴金属や、銀−パラジウム、銀−白金、白金−パラジウム等の合金を主成分とするものや、白金とセラミックス材料とのサーメット材料によって構成する。更に好適には、白金のみ又は白金系の合金を主成分とする材料によって構成する。また、電極として、カーボン、グラファイト系の材料、例えば、ダイヤモンド薄膜、ダイヤモンドライクカーボン、カーボンナノチューブも好適に使用される。なお、電極材料中に添加させるセラミックス材料の割合は、５−３０体積％程度が好適である。
【００５１】駆動電極２を形成するに当たり、上記材料を用いて、スクリーン印刷、スプレー、導電性コーティング、ディッピング、塗布、電気泳動法等の各種の厚膜形成方法や、スパッタリング、イオンビーム、真空蒸着、イオンプレーティング、ＣＶＤ、めっき等の各種の薄膜形成手法による通常の膜形成手法に従って形成することができ、好適には、これら厚膜形成手法によって形成される。
【００５２】厚膜形成手法によって駆動電極２を形成する場合、その厚さは、一般的には２０μｍ以下となり、好適には５μｍ以下となる。
【００５３】コモン電極３には、直流のオフセット電圧が印加され、図示しないスルーホールを通じて基板４の裏面から配線として引き出される。
【００５４】コモン電極３は、駆動電極２と同様な材料及び手法によって形成されるが、好適には上記厚膜形成手法によって形成する。コモン電極３の厚さも、一般的には２０μｍ以下とし、好適には５μｍ以下とする。
【００５５】駆動電極２に電気的に接続した配線と、コモン電極３に電気的に接続した配線とを電気的に分離するために、基板４を電気的な絶縁材料で構成するのが好ましい。
【００５６】したがって、基板４を、高耐熱性の金属や、その金属表面をガラスなどのセラミックス材料によって被覆したホーローのような材料によって構成することができるが、セラミックスで構成するのが最適である。
【００５７】基板４を構成するセラミックスとしては、例えば、安定化された酸化ジルコニウム、酸化アルミニウム、酸化マグネシウム、酸化チタン、スピネル、ムライト、窒化アルミニウム、窒化珪素、ガラス、これらの混合物等を使用することができる。その中でも、酸化アルミニウム及び安定化された酸化ジルコニウムが、強度及び剛性の観点から好ましい。安定化された酸化ジルコニウムは、機械的強度が比較的高いこと、靭性が比較的高いこと、駆動電極２及びコモン電極３との化学反応が比較的小さいことなどの観点から特に好適である。なお、安定化された酸化ジルコニウムとは、安定化酸化ジルコニウム及び部分安定化酸化ジルコニウムを包含する。安定化された酸化ジルコニウムでは、立方晶などの結晶構造をとるため、相転移が生じない。
【００５８】一方、酸化ジルコニウムは、１０００℃前後で単斜晶と正方晶との間を相転移し、このような相転移の際にクラックが発生するおそれがある。安定化された酸化ジルコニウムは、酸化カルシウム、酸化マグネシウム、酸化イットリウム、酸化スカンジウム、酸化イッテルビウム、酸化セリウム、希土類金属の酸化物等の安定剤を、１−３０モル％含有する。なお、基板４の機械的強度を向上させるために、安定化剤が酸化イットリウムを含有するのが好適である。この場合、酸化イットリウムを、好適には１．５−６モル％、更に好適には２−４モル％含有し、更に０．１−５モル％の酸化アルミニウムを含有するのが好ましい。
【００５９】また、結晶相を、立方晶＋単斜晶の混合相、正方晶＋単斜晶の混合相、立方晶＋正方晶＋単斜晶の混合相等とすることができるが、その中でも、主たる結晶相を、正方晶又は正方晶＋立方晶の混合相としたものが、強度、靭性及び耐久性の観点から最適である。
【００６０】基板４をセラミックスから構成した場合、比較的多数の結晶粒が基板４を構成するが、基板４の機械的強度を向上させるためには、結晶粒の平均粒径を、好適には０．０５−２μｍとし、更に好適には０．１−１μｍとする。
【００６１】電界印加部１、駆動電極２及びコモン電極３をそれぞれ形成する度に熱処理すなわち焼成して基板４と一体構造にすることができ、また、これら電界印加部１、駆動電極２及びコモン電極３を形成した後、同時に熱処理すなわち焼成して、これらを同時に基板４に一体に結合することもできる。
【００６２】なお、駆動電極２及びコモン電極３の形成手法によっては、一体化のための熱処理すなわち焼成を必要としない場合もある。
【００６３】基板４と、電界印加部１、駆動電極２及びコモン電極３とを一体化させるための熱処理すなわち焼成温度としては、一般に５００−１４００℃の範囲とし、好適には、１０００−１４００℃の範囲とする。さらに、膜状の電圧印加部１を熱処理する場合、高温時に電界印加部１の組成が不安定にならないように、電界印加部１の蒸発源とともに雰囲気制御を行いながら熱処理すなわち焼成を行うのが好ましく、また、電界印加部１を適切な部剤によってカバーし、電界印加部１の表面が焼成雰囲気に直接露出しないようにして焼成する手法を採用するのが好ましい。この場合、カバーする部材としては、基板４と同様な材料を用いることとなる。
【００６４】図２Ａは、本発明による電子放出素子の第２の実施の形態の上面図であり、図２Ｂは、そのＩＩ−ＩＩ断面図である。この電子放出素子は、電界印加部１、駆動電極２及びコモン電極３にそれぞれ対応する電界印加部１１、駆動電極１２及びコモン電極１３の他に、電界印加部１１の他方の面に形成された第４電極としての駆動端子電極１４を更に有し、基板１５の上に形成される。この場合も、好適には、電子放出素子は、放出された電子を良好に捕獲するために、電界印加部１の一方の面に対して所定の間隔を配置した第３電極としての電子捕獲電極１６を更に有し、これらの間の空間を真空状態に保持する。図２Ａにおいても、明瞭のために電子捕獲電極１６を省略している。
【００６５】本実施の形態では、駆動電極１２と駆動端子電極１４との間の電界印加部１１がコンデンサの役割を果たすので、駆動電極１２及びコモン電極１３の短絡による破損を防止するためにコンデンサを別に設ける必要がなくなる。この場合、駆動端子電極１４にパルス電圧が印加されるとともに、コモン電極１３に直流のオフセット電圧が印加される。
【００６６】駆動端子電極１４も、駆動電極１２及びコモン電極１３と同様な材料及び手法によって形成されるが、好適には上記厚膜形成手法によって形成する。駆動端子電極１４の厚さも、一般的には２０μｍ以下、好適には５μｍ以下にする。
【００６７】図３Ａは、本発明による電子放出素子の第３の実施の形態の上面図であり、図３Ｂは、そのＩＩＩ−ＩＩＩ断面図である。本実施の形態では、第１の実施の形態と同様に電界印加部２１の一方の面に駆動電極２２及びコモン電極２３が形成されるが、これら駆動電極２２及びコモン電極２３の表面には複数のカーボンナノチューブ（ＣＮＴ）が設けられており、これによって、駆動電極２２にパルス電圧を印加するとともに、コモン電極２３に直流のオフセット電圧を印加すると、ＣＮＴの先端から電子が放出されやすくなる。
【００６８】図４Ａは、本発明による電子放出素子の第４の実施の形態の上面図であり、図４Ｂは、そのＩＶ−ＩＶ断面図である。本実施の形態では、第２の実施の形態と同様に電界印加部３１の一方の面に駆動電極３２及びコモン電極３３が形成されるとともにその他方の面に駆動端子電極３４が形成されているが、これら駆動電極３２及びコモン電極３３の表面には複数のカーボンナノチューブ（ＣＮＴ）が設けられており、これによって、駆動端子電極３３にパルス電圧を印加するとともに、コモン電極３３に直流のオフセット電圧を印加すると、ＣＮＴの先端から電子が放出されやすくなる。
【００６９】図５Ａは、本発明による電子放出素子の第５の実施の形態の上面図であり、図５Ｂは、そのＶ−Ｖ断面図である。本実施の形態では、電界印加部４１の一方の面に櫛歯形状の駆動電極４２及びコモン電極４３を形成する。この場合、駆動電極４２にパルス電圧が印加されるとともに、コモン電極４３に直流のオフセット電圧が印加されると、これら駆動電極４２及びコモン電極４３の角部から電子が放出されやすくなる。
【００７０】図６Ａは、本発明による電子放出素子の第６の実施の形態の上面図であり、図６Ｂは、そのＶＩ−ＶＩ断面図である。本実施の形態では、電子放出素子は、反強誘電材料によって構成した電界印加部５１ａ，５１ｂと、その一方の面にそれぞれ形成した櫛歯形状の駆動電極５２ａ，５２ｂ及びコモン電極５３ａ，５３ｂとを有する。
【００７１】電子放出素子は、スペーサ層５４を介して基板５５の上に設けられたシート層５６の上に配置される。これによって、電界印加部５１ａ，５１ｂ、駆動電極５２ａ，５２ｂ、コモン電極５３ａ，５３ｂ、シート層５６及びスペーサ層５４は、アクチュエータ５７ａ，５７ｂをそれぞれ構成する。
【００７２】電界印加部５１ａ，５１ｂを構成する反強誘電材料としては、ジルコン酸鉛を主成分とするもの、ジルコン酸鉛とスズ酸鉛とからなる成分を主成分とするもの、ジルコン酸鉛に酸化ランタンを添付したもの、ジルコン酸鉛とスズ酸鉛とからなる成分に対してジルコン酸鉛やニオブ酸鉛を添加したものを用いるのが好適である。特に、低電圧で駆動させる場合には、ジルコン酸鉛とスズ酸鉛とからなる成分を含む反強誘電材料を用いるのが好適である。この組成は、以下のようになる。
【００７３】ＰＢ_０．９９　Ｎｂ_０．０２　［（Ｚｒ_ｘ　Ｓｎ_１−ｘ　）_１−ｙ　Ｔｉ_ｙ　］_０．９８　Ｏ_３
【００７４】また、反強誘電材料を多孔質にすることもでき、この場合、気孔率を３０％以下にするのが好適である。
【００７５】電界印加部５１ａ，５１ｂを形成するに当たり、上記厚膜形成手法を用いて形成するのが好適であり、微細な印刷を廉価に行うことができるという理由から、スクリーン印刷法が特に好適に用いられる。なお、電界印加部５１ａ，５１ｂの厚さとしては、低作動電圧で大きな変位を得るなどの理由から、スクリーン印刷法が特に好適に用いられる。なお、電界印加部５１ａ，５１ｂの厚さとしては、低作動電圧で大きな変位を得るなどの理由から、好適には５０μｍ以下とし、更に好適には、３−４０μｍとする。
【００７６】このような厚膜形成手法によって、平均粒子径が０．０１−７μｍ程度、好適には０．０５−５μｍ程度の反強誘電材料のセラミック粒子を主成分とするペーストやスラリーを用いて、シート層５６の表面上に膜形成することができ、良好な素子特性が得られる。
【００７７】電気泳動法は、高密度かつ高い形状制御で膜を形成でき、技術文献「ＤＥＮＫＩ　ＫＡＧＡＫＵ　５３，Ｎｏ．１（１９８５），ｐ６３−６８　安斎和夫著」や、「第１回電気泳動法によるセラミックスの高次成形法　研究討論会　予稿集（１９９８），ｐ５−６．ｐ２３−２４」に記載されているような特徴を有する。したがって、要求精度、信頼性等を考慮して、各種手法を適切に選択して用いるのが好適である。
【００７８】シート層５６は、比較的肉薄に形成され、外部応力に対して振動を受けやすい構造となっている。シート層５６を、好適には高耐熱性材料で構成する。その理由は、図２及び４のように駆動端子電極をシート層５６に直接接合するに当たり、有機接着剤などの耐熱性の比較的低い材料を使用することなくシート層５６を直接支持する構造をとる場合、少なくとも電界印加部５１ａ，５１ｂの形成時にシート層５６が変質するのを防止するためである。なお、シート層５６をセラミックスで構成する場合、図１の基板４と同様に構成する。
【００７９】スペーサ層５４を、好適にはセラミックスから構成するが、それを、シート層５６を構成するセラミックス材料と同一とすることも、それとは異なるセラミックス材料とすることもできる。そのようなセラミックスとしては、シート層５６を構成するセラミックス材料と同様に、例えば、安定化された酸化ジルコニウム、酸化アルミニウム、酸化マグネシウム、酸化チタン、スピネル、ムライト、窒化アルミニウム、窒化珪素、ガラス、これらの混合物等を使用することができる。
【００８０】スペーサ層５４、基板５５及びシート層５６を構成するセラミックス材料と異なるセラミックス材料としては、酸化ジルコニウムを主成分とする材料、酸化アルミニウムを主成分とする材料、これらの混合物を主成分とする材料等が好適に採用される。その中でも、酸化ジルコニウムを主成分としたものが特に好ましい。なお、焼結助剤として粘土などを添付することもあるが、酸化珪素、酸化ホウ素等のガラス化しやすいものが過剰に含まれないように、助剤成分を調整する必要がある。その理由は、これらガラス化しやすい材料は、電界印加部５１ａ，５１ｂとの接合の観点からは有利であるが、電界印加部５１ａ，５１ｂとの反応を促進し、電界印加部５１ａ，５１ｂが所定の組成を維持するのが困難となり、その結果、素子特性を低下させる原因となるからである。
【００８１】すなわち、スペーサ層５４、基板５５及びシート層５６に含まれる酸化珪素などを、重量比で３％以下、好適には１％以下となるように制限するのが好ましい。ここで、主成分とは、重量比で５０％以上の割合で存在する成分をいう。
【００８２】スペーサ層５４、基板５５及びシート層５６を３層の積層体として構成するのが好適であり、この場合、例えば、一体同時焼成、ガラスや樹脂によって各層を接合一体化又は後付けを行う。なお、４層以上の積層体とすることもできる。
【００８３】本実施の形態のように電界印加部５１ａ，５１ｂを反強誘電体材料によって構成した場合、電界が加えられない状態では、電界印加部５１ｂのように平坦形状となり、それに対して、電界が加えられると、電界印加部５１ａのように凸状に屈曲変位する。このように凸状に屈曲変位することによって、電子放出素子とそれに対向する電子捕獲電極５８との間の間隔が狭くなるので、矢印で示したように発生する電子の直進性が更に良好になる。したがって、この屈曲変位量を以って、電子捕獲電極５８に到達する放出電子量を制御することが可能である。
【００８４】次に、本発明による電子放出素子の動作を説明する。
図７は、本発明による電子放出素子の動作を説明するための図である。この場合、電流制御素子６１は、図１に示す構成を有し、その周辺は、真空チャンバ６２によって真空状態に保持される。また、駆動電極６３とコモン電極６４との間の短絡を防止するために、駆動電極６３と電圧信号源６５との間にコンデンサ６６を直列配置している。駆動電極６３及びコモン電極６４に対向する電子捕獲電極６７には、バイアス電圧Ｖｂが印加される。
【００８５】信号電圧源６５に印加される電圧Ｖ_１　を−４００Ｖとし、コンデンサ６６の容量を５００ｐＦとし、バイアス電圧Ｖｂを０Ｖとし、駆動電極６３とコモン電極６４とによって形成されるスリットの幅を１０μｍとし、真空チャンバ６２の内部の真空度を１×１０^−３　Ｐａとした場合、駆動電極６３に流れる電流Ｉ_１　が２．０Ａとなり、電子捕獲電極６７から取り出されるコレクタ電流Ｉｃの密度が１．２Ａ／ｃｍ^２　となる。その結果、本発明の電子放出素子によれば、従来の電子放出素子に比べて、低い電圧及び低い真空度で高い電流密度が得られ、その結果、優れた直進性を示す。なお、図７Ｂに示すように、コレクタ電流Ｉｃは、バイアス電圧Ｖｂが高くなるに従って大きくなる。
【００８６】図８は、本発明による他の電子放出素子の動作を説明するための図である。この場合、電流制御素子７１は、図２に示す構成を有し、その周辺は、真空チャンバ７２によって真空状態に保持される。また、駆動電極７３とコモン電極７４との間の短絡を防止するために、駆動電極７３と駆動端子電極７５との間の電界印加部７６がコンデンサの役割を果たす。駆動電極７３及びコモン電極７４には、電子捕獲電極７７が対向する。
【００８７】信号電圧源７８に印加される電圧Ｖ_１　を−４００Ｖとし、電界印加部７６が５３０ｐＦの容量のコンデンサの役割を果たし、駆動電極７３とコモン電極７４とによって形成されるスリットの幅を１０μｍとし、真空チャンバ７２の内部の真空度を１×１０^−３　Ｐａとした場合、駆動端子電極７５に流れる電流Ｉ_１　が２．０Ａとなり、電子捕獲電極７７から取り出されるコレクタ電流Ｉｃの密度が１．２Ａ／ｃｍ^２　となる。その結果、本発明の他の電子放出素子によれば、従来の電子放出素子に比べて、低い電圧及び低い真空度で高い電流密度が得られ、その結果、優れた直進性を示す。なお、電圧Ｖ_１　，電流Ｉｃ，Ｉ_１　，Ｉ_２　の波形を、図８Ｂにおいて曲線ａ−ｄでそれぞれ示す。
【００８８】図９は、本発明によるＦＥＤの実施の形態を示す図である。このＦＥＤは、２次元的に配列された複数の電子放出素子８１Ｒ，８１Ｇ，８１Ｂと、これら電子放出素子８１Ｒ，８１Ｇ，８１Ｂに対してそれぞれ所定の間隔を以って配置した赤色蛍光体８２Ｒ、緑色蛍光体８２Ｇ及び青色蛍光体８２Ｂとを具える。
【００８９】本実施の形態では、電子放出素子８１Ｒ，８１Ｇ，８１Ｂが基板８３に形成され、赤色蛍光体８２Ｒ、緑色蛍光体８２Ｇ及び青色蛍光体８２Ｂが電子捕獲電極８４を介してガラス基板８５に形成される。電子放出素子８１Ｒ，８１Ｇ，８１Ｂは、図２に示す構造を有するが、図１，３−６のうちのいずれかの構造を有することもできる。
【００９０】本実施の形態によれば、電子放出素子８１Ｒ，８１Ｇ，８１Ｂの直進性が優れているので、従来の電子放出素子を有する場合に比べてクロストークが小さくなり、蛍光体８２Ｒ，８２Ｇ，８２Ｂのピッチを狭くすることができ、かつ、隣接する蛍光体８２Ｒ，８２Ｇ，８２Ｂに電子が入射されるのを防止するためにグリッドを設ける必要がなくなる。その結果、本実施の形態のＦＥＤは、小型化及びコスト低減の観点から好ましい。なお、真空度が比較的低い場合でも電子の放出が可能であるので、真空空間を予め大きくして真空度の低下に対するマージンをみる必要がなくなり、ＦＥＤの薄型化の制約が少なくなる。
【００９１】図１０は、本発明による電子放出素子の比誘電率と印加電圧との関係を示す図であり、図１１は、それを説明するための図である。図１０の特性は、図１１に示すように駆動電極９１とコモン電極９２ａ−９２ｃとによって形成されるスリットの幅ｄ１，ｄ２がいずれも１０μｍである場合の電界印加部の比誘電率と、電界の放出に必要な印加電圧との関係を示す図である。
【００９２】図１０に示すように、従来の電子放出素子に比べて低い印加電圧を用いて電子放出素子を駆動させる場合、比誘電率を１０００以上にするのが好ましいことがわかる。
【００９３】図１２は、本発明による電子放出素子のスリット幅と印加電圧との関係を示す図である。図１２から、電子放出現象が生じるためにはスリット幅を５００μｍ以下にする必要があることがわかる。なお、市販のプラズマディスプレイ、蛍光表示管又は液晶ディスプレイで用いられるドライバＩＣで本発明による電子放出素子を駆動するためには、スリット幅を２０μｍ以下にする必要がある。
【００９４】図１３Ａは、本発明による電子放出素子の第７の実施の形態の上面図であり、図１３Ｂは、そのＶＩＩ−ＶＩＩ断面図である。本実施の形態では、電界印加部１０１の一方の側に半円形状の駆動電極１０２及びコモン電極１０３を形成し、駆動電極１０２、コモン電極１０３及びこれらによって形成されたスリットに導電性コーティング部１０４を設ける。
【００９５】図１３に示す構成を有する電子放出素子の動作を、図１４を用いて説明する。この場合、電流放出素子の周辺は、真空チャンバ１１１によって真空状態に保持される。駆動電極１０２とコモン電極１０３との間の短絡を防止するために、駆動電極１０２と電圧信号源１１２との間にコンデンサ１１３を直列配置している。駆動電極１０２及びコモン電極１０３に対向する電子捕獲電極１１４には、蛍光体１１５が設けられ、バイアス電圧Ｖｂが印加される。
【００９６】駆動電極１０２及びコモン電極１０３は、膜厚３μｍのＡｕであり、これら駆動電極１０２及びコモン電極１０３と、その間のスリット部とに対して、カーボンによる導電性コーティング部１０４（膜厚３μｍ）を設けた。信号電圧源１１２に印加されるパルス電圧Ｖｋを２５Ｖとし、コンデンサ１１３の容量を５ｎＦとし、バイアス電圧Ｖｂを３００Ｖとし、電界印加部１０１を、比誘電率が１４０００の電歪材料で構成し、駆動電極１０２とコモン電極１０３とによって形成されるスリットの幅を１０μｍとし、真空チャンバ１１１の内部の真空度を１×１０^−３　Ｐａとした場合、電子捕獲電極１１４に流れる電流Ｉｃは０．１Ａとなり、駆動電極１０２に流れる電流Ｉ_１　（０．２５Ａ）に対して約４０％の電流を電子流として取り出しており、駆動電極１０２とコモン電極１０３との間の電圧Ｖｓ、すなわち、電子の放出に必要な電圧が２３．８Ｖとなる。その結果、図１３に示す電子放出素子によれば、電子の放出に必要な電圧を著しく低くすることができる。また、導電性コーティング部１０４によって、電子又はイオンの衝突や発熱によって駆動電極１０２及びコモン電極１０３が損傷されるおそれが著しく軽減される。なお、駆動電極１０２に流れる電流Ｉ_１　，コモン電極１０３に流れる電流Ｉ_２　，Ｉｃ及び電圧Ｖｓの波形を、図１４Ｂにおいて曲線ｅ−ｈでそれぞれ示す。
【００９７】導電性コーティング部１０４は、駆動電極１０２及び／又はコモン電極１０３の保護膜として機能する。具体的には、電子放出時にスリット部近傍に生成され、印加電圧により加速されるイオンや電子の衝突や、それに伴う発熱による駆動電極１０２及び／又はコモン電極１０３の損傷を防止する。この観点から、導電性コーティング１０４としては、スパッタ率が小さく、かつ、融点の高い材料から構成されるのが好ましい。
【００９８】なお、導電性コーティング部１０４としては、カーボンの他に、高温酸化雰囲気に対して耐性を有する導体、例えば金属単体、合金、絶縁性セラミックスと金属単体との混合物、絶縁性セラミックスと合金との混合物等によって構成し、好適には、白金、パラジウム、ロジウム、モリブデン等の高融点貴金属や、銀−パラジウム、銀−白金、白金−パラジウム等の合金を主成分とするものや、白金とセラミックス材料とのサーメット材料によって構成する。更に好適には、白金のみ又は白金系の合金を主成分とする材料によって構成する。また、導電性コーティング部１０４として、グラファイト系の材料、例えば、ダイヤモンド薄膜、ダイヤモンドライクカーボン、カーボンナノチューブも好適に使用される。なお、導電性コーティング材料中に添加させるセラミックス材料の割合は、５−３０体積％程度が好適である。導電性コーティング部１０４の抵抗値を、例えば数キロΩ〜１００キロΩとするのが好ましい。導電性コーティング部１０４を、蒸着カーボン（具体例として、サンユー工業社製「ＣＡＲＢＯＮ　５ＰＣ」を蒸着したもの）、刷り込みカーボン（具体例として、Ｄｅｇｕｓｓａ社製「ＦＷ２００」など）、印刷カーボン等によって形成する。さらに、アルカリ金属やアルカリ土類金属の酸化物、特に酸化マグネシウムの薄膜で被覆された導電性膜も、導電性コーティング部１０４として好適に使用される。
【００９９】図１５Ａは、本発明による電子放出素子の第８の実施の形態の上面図であり、図１５Ｂは、そのＶＩＩＩ−ＶＩＩＩ断面図である。本実施の形態では、電界印加部１１１の一方の側に半円形状の駆動電極１１２及びコモン電極１１３を形成し、駆動電極１１２に導電性コーティング部１１４ａを形成するとともに、コモン電極１１３に、導電性コーティング部１１４ａとは非接触状態の導電性コーティング部１１４ｂを形成する。
【０１００】このような電子放出素子は、電界印加部１２１の一方の側に駆動電極１２２及びコモン電極１２３を印刷によって形成した後、駆動電極１２２、コモン電極１２３及びこれらによって形成されたスリット１２４に、導電性材料をカーボン蒸着してコーティング部１２５を形成し（図１６Ａ）、スリット１２４に対して、レーザ照射源１２６からレーザビーム１２７を照射し（図１６Ｂ）、導電性コーティング部１２５ａ及びそれとは非接触状態の導電性コーティング部１２５ｂを形成することによって得られる。なお、電界印加部１２１の一方の側に駆動電極１２２及びコモン電極１２３を印刷によって形成した後、導電性コーティング部１２５ａ及びそれとは非接触状態の導電性コーティング部１２５ｂを印刷することによって、図１６Ｃに示す構造の電子放出素子を得ることもできる。また、フォトリソグラフィのような薄膜技術を応用することによって、図１６Ｃに示す構造の電子放出素子を得ることもできる。
【０１０１】本発明による電子放出素子の第８の実施の形態によれば、第１の導電性コーティング部及びそれとは非接触状態の第２の導電性コーティング部によって、電子又はイオンの衝突や発熱による駆動電極及びコモン電極の損傷のおそれが著しく軽減されるとともに、電子放出素子を駆動回路で使用した際の駆動電圧が大幅に低減される。このような駆動電圧の大幅な低減について詳細に説明する。上記第７の実施の形態の電子放出素子をジルコニア基板１３１上に配置し、駆動電極１３２をパルス上の信号を発生する信号電圧源１３３に接続するとともに、コモン電極１３４を接地した場合（図１７Ａ）、駆動電極１３２とコモン電極１３４との間の等価回路ａは、抵抗ａ１及びこれに並列接続したコンデンサａ２を有する（図１７Ｂ）。抵抗ａ１を通じて直流が流れるのを防止するために、信号電圧源１３３と電子放出素子との間に直流カット用のコンデンサ１３５が設けられる。それに対して、上記第８の実施の形態の電子放出素子をジルコニア基板１４１上に配置し、駆動電極１４２を、パルス状の信号を発生する信号電圧源１４３に接続するとともに、コモン電極１４４を接地した場合（図１７Ｃ）、駆動電極１４２とコモン電極１４４との間の等価回路ｂはコンデンサｂ１のみを有する（図１７Ｄ）。等価回路ｂが抵抗を有しないので、信号電圧源１４３と電子放出素子との間に直流カット用のコンデンサを設ける必要がなくなる。駆動電圧が直流カット用のコンデンサによって分圧されなくなるので、駆動回路で使用した際の駆動電圧が、上記第７の実施の形態の場合に比べて大幅に低減され、高電圧での駆動が不要となり、その結果、回路を廉価に構成することができる。
【０１０２】図１８Ａは、本発明による電子放出素子の第９の実施の形態の上面図であり、図１８Ｂは、そのＩＸ−ＩＸ断面図である。本実施の形態では、電界印加部２０１の一方の側に半円形状の駆動電極２０２及びコモン電極２０３を形成するとともに、駆動電極２０２に導電性コーティング部２０４ａを形成するとともに、コモン電極２０３に、導電性コーティング部２０４ａとは非接触状態の導電性コーティング部２０４ｂを形成する。また、導電性コーティング部２０４ａ，２０４ｂよりも抵抗率が高い材料で構成されるとともに導電性コーティング部２０４ａ，２０４ｂに電気的に接触する高抵抗部２０５を、駆動電極２０２及びコモン電極２０３によって形成されたスリットに設ける。
【０１０３】駆動電極２０２とコモン電極２０３との間の等価回路は、図１８Ｃに示すように、駆動電極２０２、導電性コーティング部２０４ａ、高抵抗部２０５、導電性コーティング部２０４ｂ及びコモン電極２０３にそれぞれ対応する端子ｘ１、抵抗ｘ２，ｘ３，ｘ４及び端子ｘ５を有する。電子放出素子に電圧が印加されると、高抵抗部２０５の電圧は、導電性コーティング部２０４ａ，２０４ｂの電圧より高くなり、高抵抗部２０５すなわちスリットにおける電界の集中度が向上する。その結果、低い印加電圧で電子を放出することができ、消費電力が低減し、かつ、回路の小型化及び高電圧対応部品の省略によるコストダウンを図ることができる。
【０１０４】図１９は、図１８の電子放出素子の変形例を示す図である。図１９Ａ及び１９Ｂでは、互いに接触しない二つの導電性コーティング部よりも抵抗率が高い材料で構成されるとともにこれら導電性コーティング部に電気的に接触する高抵抗部を、駆動電極及びコモン電極によって形成されたスリットに設ける。図１９Ｃでは、互いに接触しない二つの導電性コーティング部と同一材料で構成されるとともにこれら導電性コーティング部に電気的に接触し、かつ、これら導電性コーティング部よりも肉薄の高抵抗部を、駆動電極及びコモン電極によって形成されたスリットに設ける。このような高抵抗部は、例えば、スリット上の導電性コーティング部にレーザを照射し、駆動電極及びコモン電極上に形成された導電性コーティング部に比べて肉薄の導電性コーティング部を形成することによって、得られる。
【０１０５】図２０は、本発明による電子放出素子の第１０の実施の形態を示す図である。本実施の形態では、電子放出素子を酸化ジルコニウム（ジルコニア）基板上に設けたものであり、酸化ジルコニウム基板上には、例えば、図１３に示す電子放出素子（図２０Ａ）、図１５に示す電子放出素子（図２０Ｂ）、図１８に示す電子放出素子（図２０Ｃ）、図１９Ａに示す電子放出素子（図２０Ｄ）、図１９Ｂに示す電子放出素子（図２０Ｅ）及び図１９Ｃに示す電子放出素子（図２０Ｆ）が配置される。既に説明したように、基板を酸化ジルコニウムで構成することは、強度、靭性及び耐久性の観点から好適である。
【０１０６】図２１Ａは、本発明による電子放出素子の第１１の実施の形態の上面図であり、図２１Ｂは、そのＸ−Ｘ断面図である。本実施の形態では、電界印加部３０１の一方の側に半円形状の駆動電極３０２及びコモン電極３０３を形成する。
【０１０７】図２１に示す構成を有する電子放出素子の場合、すなわち、導電性コーティングを有しない場合でも、２００Ｐａ以下の低い真空度で電子を放出することとを、図２２を用いて説明する。この場合、電流放出素子の周辺は、真空チャンバ３１１によって真空状態に保持される。駆動電極３０２とコモン電極３０３との間の短絡を防止するために、駆動電極３０２と電圧信号源２１２との間にコンデンサ２１３を直列配置している。駆動電極３０２及びコモン電極３０３に対向する電子捕獲電極３１４には、蛍光体３１５が設けられ、バイアス電圧Ｖｂが印加される。
【０１０８】駆動電極３０２及びコモン電極３０３の材質は共にＡｕであり、信号電圧源３１２に印加されるパルス電圧Ｖｋを１６０Ｖとし、コンデンサ３１３の容量を５ｎＦとし、バイアス電圧Ｖｂを３００Ｖとし、電界印加部３０１を、比誘電率が４５００の電歪材料で構成し、駆動電極３０２とコモン電極３０３とによって形成されるスリットの幅を１０μｍとし、真空チャンバ３１１の内部の真空度を２００Ｐａ以下とした場合、電子捕獲電極３１４に流れる電流Ｉｃは１．２Ａとなり、駆動電極３０２に流れる電流Ｉ_１　（２Ａ）に対して約６０％の電流を電子流として取り出しており、駆動電極３０２とコモン電極３０３との間の電圧Ｖｓ、すなわち、電子の放出に必要な電圧が１５３Ｖとなる。なお、電流Ｉ_１　，Ｉ_２　，Ｉｃ及び電圧Ｖｓの波形を、図２２Ｂにおいて曲線ｉ−ｌでそれぞれ示す。
【０１０９】上記のように２００Ｐａ以下の非常に低い真空度で十分な電子放出が可能なのは、導電性コーティング部を有する場合も同様である。
【０１１０】本発明による電子放出素子によれば、２００Ｐａ以下の非常に低い真空度で電子を放出することができるので、ＦＥＤを構成する場合、パネル外周部の封止空間を非常に小さくすることができるので、狭額縁パネルを実現することができる。また、複数のパネルを並べてディスプレイを大型化する場合、パネル間の継ぎ目が目立ちにくくなる。さらに、従来のＦＥＤでは、蛍光体などから発生するガスによるＦＥＤの内部空間の真空度が低下し、パネルの耐久性に悪影響を及ぼすおそれがあるが、本発明による電子放出素子を用いたディスプレイによれば、２００Ｐａ以下の非常に低い真空度で電子を放出することができるので、ＦＥＤの内部空間の真空度の低下による悪影響が大幅に軽減され、パネルの耐久性及び信頼性が大幅に向上する。
【０１１１】本発明による電子放出素子及びそれを用いたＦＥＤによれば、従来に比べて簡単かつ小型化にすることができる。これについて具体的に説明すると、先ず、ＦＥＤの内部空間の真空度を低くすることができるので、ＦＥＤの外周封止部などの内外圧力差に対する筐体維持構造を簡単かつ小型化にすることができる。
【０１１２】また、電子を放出するために必要な印加電圧及び電子捕獲電極に印加すべきバイアス電圧を比較的低くすることができるので、ＦＥＤを耐圧構造とする必要がなくなり、装置全体の小型化及びパネルの薄型化が可能となる。なお、電子捕獲電極に印加すべきバイアス電圧を、０Ｖとしてもよい。
【０１１３】また、本発明による電子放出素子の電界印加部を構成するに際し、スピント型の電子放出素子を構成する場合のように特殊な加工を必要とせず、さらに、電極及び電界印加部を厚膜印刷で形成できるので、本発明による電子放出素子及びそれを用いたＦＥＤを、従来に比べて低コストで製造することができる。
【０１１４】さらに、電子を放出するために必要な印加電圧及び電子捕獲電極に印加すべきバイアス電圧を比較的低くすることができるので、耐圧が比較的小さい小型で廉価な駆動ＩＣを使用することができるので、本発明による電界放出素子を用いたＦＥＤを廉価に製造することができる。
【０１１５】本発明は、上記実施の形態に限定されるものではなく、幾多の変更及び変形が可能である。
例えば、本発明による電子放出素子を、バックライトのような他のアプリケーションに適用することもできる。本発明による電子放出素子は、比較的大量の電子線を比較的低い電圧で放出することができるので、紫外線放射方式が主流であった従来の殺菌装置に代えて、小型かつ高効率の殺菌装置を構成するのに好適である。また、本発明による電子放出素子は、角部を有する他の任意の電極構造を採用することができる。さらに、駆動電極とコモン電極との間の短絡を防止するために、第２電極すなわちコモン電極と直流オフセット電圧源との間に抵抗を直列配置することもできる。
【０１１６】第６の実施の形態において、電界印加部５１ａ，５１ｂを反誘電材料によって構成した場合について説明したが、電界印加部５１ａ，５１ｂを、圧電材料、電歪材料及び反誘電材料のうちの少なくとも１種類によって構成すればよい。圧電材料及び／又は電歪材料を用いる場合、例えば、ジルコン酸鉛（ＰＺ系）を主成分とする材料、ニッケルニオブ酸鉛を主成分とする材料、亜鉛ニオブ酸鉛を主成分とする材料、マンガンニオブ酸鉛を主成分とする材料、マグネシウムタンタル酸鉛を主成分とする材料、ニッケルタンタル酸鉛を主成分とする材料、アンチモンスズ酸鉛を主成分とする材料、チタン酸鉛を主成分とする材料、マグネシウムタングステン酸鉛を主成分とする材料、コバルトニオブ酸鉛を主成分とする材料又はこれらの任意の組合せを含有する複合材料を用いることができ、これらのうち、ジルコン酸鉛を含有するセラミックスが圧電材料及び／又は電歪材料として最も使用頻度が高い。
【０１１７】圧電材料及び／又は電歪材料をセラミックスとした場合、上記材料に、ランタン、バリウム、ニオブ、亜鉛、セリウム、カドミウム、クロム、コバルト、アンチモン、鉄、イットリウム、タンタル、タングステン、ニッケル、マンガン、リチウム、ストロンチウム、ビスマス等の酸化物若しくはこれらのいずれかの組合せ又は他の化合物を適切に添加した適切な材料とし、例えばＰＬＺＴ系となるようにその材料に所定の添加物を加えたものも好適に用いられる。
【０１１８】これら圧電材料及び／又は電歪材料の中でも、マグネシウムニオブ酸鉛とジルコン酸鉛とチタン酸鉛とからなる成分を主成分とする材料、ニッケルニオブ酸鉛とマグネシウムニオブ酸鉛とジルコン酸鉛とチタン酸鉛とからなる成分を主成分とする材料、マグネシウムニオブ酸鉛とニッケルタンタル酸鉛とジルコン酸鉛とチタン酸鉛とからなる成分を主成分とする材料、マグネシウムタンタル酸鉛とマグネシウムニオブ酸鉛とジルコン酸鉛とチタン酸鉛とからなる成分を主成分とする材料、これらの材料の鉛の一部をストロンチウム及び／又はランタンで置換したもの等が好適に用いられ、上記スクリーン印刷などの厚膜形成手法で電界印加部５１ａ，５１ｂを形成する場合の材料として好適である。
【０１１９】多成分系圧電材料及び／又は電歪材料の場合、成分の組成によって、圧電及び／又は電歪特性が変化するが、第６の実施の形態で好適に採用されるマグネシウムニオブ酸鉛−ジルコン酸鉛−チタン酸鉛の３成分系材料や、マグネシウムニオブ酸鉛−ニッケルタンタル酸鉛−チタン酸鉛及びマグネシウムタンタル酸鉛−マグネシウムニオブ酸鉛−ジルコン酸鉛−チタン酸鉛の４成分系材料では、疑立方晶−正方晶―菱面体晶の相境界付近の組成が好ましく、特に、マグネシウムニオブ酸鉛：１５−５０モル％、ジルコン酸鉛：１０−４５モル％、チタン酸鉛：３０−４５モル％の組成や、マグネシウムニオブ酸鉛：１５−５０モル％、ニッケルタンタル酸鉛：１０−４０モル％、ジルコン酸鉛：１０−４５モル％、チタン酸鉛：３０−４５モル％の組成及びマグネシウムニオブ酸鉛：１５−５０モル％、マグネシウムタンタル酸鉛：１０−４０モル％、ジルコン酸鉛：１０−４５モル％、チタン酸鉛：３０−４５モル％の組成が、高圧電定数及び項電気機械結合係数を有する理由から好適に採用される。
【０１２０】第９の実施の形態において、高抵抗部を、導電性材料の分布がまばらになったもの、導電性材料を局所的に破壊、変形若しくは変質させることによって構造変化させたもの、導電性コーティング部を高電圧の印加などによって加工して、導電性材料を局所的に破壊、変形若しくは変質させることによる構造変化若しくは微小クラックを発生させたもの、圧電効果により、電界をかけたときのみスリットが膨張し、それに伴って抵抗値が高くなるもの、又は、圧電効果により微小クラックが入り、それに伴って抵抗値が高くなるものとしてもよい。なお、圧電効果により、電界をかけたときのみスリットが膨張し、それに伴って抵抗値が高くなるものとした場合、製造時の前処理を省略することができるという利点がある。
【図面の簡単な説明】
【図１】本発明による電子放出素子の第１の実施の形態を示す図である。
【図２】本発明による電子放出素子の第２の実施の形態を示す図である。
【図３】本発明による電子放出素子の第３の実施の形態を示す図である。
【図４】本発明による電子放出素子の第４の実施の形態を示す図である。
【図５】本発明による電子放出素子の第５の実施の形態を示す図である。
【図６】本発明による電子放出素子の第６の実施の形態を示す図である。
【図７】本発明による電子放出素子の動作を説明するための図である。
【図８】本発明による他の電子放出素子の動作を説明するための図である。
【図９】本発明によるＦＥＤの実施の形態を示す図である。
【図１０】本発明による電子放出素子の比誘電率と印加電圧との関係を示す図である。
【図１１】図１０を説明するための図である。
【図１２】本発明による電子放出素子のスリット幅と印加電圧との関係を示す図である。
【図１３】本発明による電子放出素子の第７の実施の形態を示す図である。
【図１４】図１３の電子放出素子の動作を説明するための図である。
【図１５】本発明による電子放出素子の第８の実施の形態を示す図である。
【図１６】図１５の電子放出素子の製造を説明するための図である。
【図１７】図１５の電子放出素子の効果を説明するための図である。
【図１８】本発明による電子放出素子の第９の実施の形態を示す図である。
【図１９】図１８の電子放出素子の変形例を示す図である。
【図２０】本発明による電子放出素子の第１０の実施の形態を示す図である。
【図２１】本発明による電子放出素子の第１１の実施の形態を示す図である。
【図２２】図２１の電子放出素子の動作を説明するための図である。[0001]
[0001] 1. Field of the Invention [0002] The present invention relates to an electron-emitting device and a field emission display using the same.
[0002]
2. Description of the Related Art Such an electron-emitting device has a driving electrode and a grounding electrode, and is applied to various applications such as a field emission display (FED) and a backlight (for example, see Patent Literatures 1 to 5 and Non-Patent Literatures 1 to 3). When applied to an FED, a plurality of electron-emitting devices are two-dimensionally arranged, and a plurality of phosphors for these electron-emitting devices are arranged at predetermined intervals.
[0003]
However, the straightness of the conventional electron-emitting device, that is, the degree to which the emitted electrons go straight to a predetermined object (for example, a phosphor) is not good, and the desired degree of the emitted electrons depends on the emitted electrons. It is necessary to apply a relatively high voltage to the electron-emitting device in order to secure the current density of the electron-emitting device.
[0004]
[Patent Document 1] Japanese Patent Application Laid-Open No. 1-311,533 (page 3, FIG. 1)
[Patent Document 2] Japanese Patent Application Laid-Open No. 7-147,131 (page 3, FIG. 8 and FIG. 9)
[Patent Document 3] JP-A-2000-285,801 (page 5, FIG. 3)
[Patent Document 4] Japanese Patent Publication No. 46-20,944 (page 1, FIG. 2)
[Patent Document 5] Japanese Patent Publication No. 44-26125 (page 1, FIG. 2)
[Non-Patent Document 1] Yasuoka and Ishii, "Pulse Electron Source Using Ferroelectric Cathode", Applied Physics, Vol. 68, No. 5, p. 546-550 (1999)
[Non-Patent Document 2] F. Puchkarev, @G. A. Meyats, On the mechanism of emissionfrom the ferroelectric ceramic cathode, J. {Appl. {Phys. , @Vol. 78, No. 9 November, 1995, p. 5633-5637
[Non-Patent Document 3] Riege, \ Electron \ emission \ ferroelectrics-a \ review, \ Nucl. Instr. {And} Meth. A340, p. 80-89 (1994)
Further, when a conventional electron-emitting device is applied to an FED, crosstalk becomes relatively large due to poor linearity. That is, emitted electrons are emitted from a phosphor adjacent to a corresponding phosphor. Is more likely to be incident. As a result, it becomes difficult to reduce the pitch of the phosphors, and it is necessary to provide a grid in order to prevent electrons from being incident on adjacent phosphors.
An object of the present invention is to provide an electron-emitting device having good straightness of emitted electrons and a field emission display using the same.
Another object of the present invention is to provide an electron-emitting device which realizes electron emission having a high current density at a relatively low vacuum and a very low driving voltage, and a field emission display using the same. is there.
[0008]
An electron-emitting device according to the present invention comprises:
An electric field application unit formed of a dielectric,
A first electrode formed on one surface of the electric field application unit;
A second electrode formed on one surface of the electric field applying unit and forming a slit together with the first electrode.
According to the present invention, when a pulse voltage is applied to the first or second electrode, electrons are emitted from the electric field application unit. By forming the electric field application unit with a dielectric, it is possible to obtain a good straightness that cannot be achieved by the conventional electron-emitting device. As a result, the voltage applied to the electron-emitting device in order to secure a desired current density becomes significantly lower than in the prior art, and the energy consumption is greatly reduced. In addition, since the first and second electrodes can be formed in the electric field application section by thick film printing, the electron-emitting device according to the present invention is preferable from the viewpoint of durability and cost reduction.
[0010] In order to further reduce the voltage applied to the electron-emitting device, it is preferable to further include a conductive coating portion provided on the first electrode, the second electrode, and the slit. In this case, the possibility of damage to the first and second electrodes due to collision of electrons and / or ions and heat generation is significantly reduced by the conductive coating portion.
More preferably, a first conductive coating portion provided on the first electrode,
The first coating portion further includes a second conductive coating portion provided on the second electrode in a non-contact state. In this case, a resistor is not included in the equivalent circuit between the first electrode and the second electrode, so that a DC cut capacitor is not required, and driving at a high voltage is not required. Voltage can be further reduced. Also in this case, the first and second conductive coatings significantly reduce the risk of damage to the first and second electrodes due to collision of electrons and / or ions and heat generation.
The slit may be provided with a high-resistance portion having a higher resistance than the first and second conductive coating portions and electrically contacting the first and second conductive coating portions. In this case, when a voltage is applied to the electron-emitting device, the voltage of the high resistance portion becomes higher than the voltages of the first and second conductive coating portions, and the concentration of the electric field in the high resistance portion, that is, the slit is improved. As a result, electrons can be emitted with a lower applied voltage than when no high-resistance portion is provided, power consumption is reduced, and cost is reduced by downsizing the circuit and omitting high-voltage compatible components. Can be.
In order to satisfactorily emit electrons, there is further provided a third electrode disposed at a predetermined distance from the first and second electrodes, and the first and second electrodes and the third electrode are provided. Preferably, the space between the three electrodes is evacuated.
Another electron-emitting device according to the present invention is:
An electric field applying unit formed of at least one of a piezoelectric material, an electrostrictive material, and an antiferroelectric material,
A first electrode formed on one surface of the electric field application unit;
A second electrode formed on one surface of the electric field applying unit and forming a slit together with the first electrode.
According to the present invention, when a pulse voltage is applied to the first or second electrode, the electric field applying section may function as an actuator and bend and displace. As a result, the straightness of the electron-emitting device is further improved.
In order to further reduce the voltage applied to the electron-emitting device, it is preferable to further include a conductive coating provided on the first electrode, the second electrode and the slit. In this case, the conductive coating significantly reduces the risk of damage to the first and second electrodes due to collision of electrons and / or ions and heat generation.
More preferably, a first conductive coating portion provided on the first electrode,
The first coating portion further includes a second conductive coating portion provided on the second electrode in a non-contact state. In this case, a resistor is not included in the equivalent circuit between the first electrode and the second electrode, so that a DC cut capacitor is not required, and driving at a high voltage is not required. Voltage can be further reduced. Also in this case, the first and second conductive coatings significantly reduce the risk of damage to the first and second electrodes due to collision of electrons and / or ions and heat generation.
The slit may be provided with a high-resistance portion having a higher resistance than the first and second conductive coating portions and electrically contacting the first and second conductive coating portions. In this case, when a voltage is applied to the electron-emitting device, the voltage of the high resistance portion becomes higher than the voltages of the first and second conductive coating portions, and the concentration of the electric field in the high resistance portion, that is, the slit is improved. As a result, electrons can be emitted with a lower applied voltage than when no high-resistance portion is provided, power consumption is reduced, and cost is reduced by downsizing the circuit and omitting high-voltage compatible components. Can be.
Also in this case, in order to satisfactorily emit electrons, a third electrode arranged at a predetermined distance from the first and second electrodes is further provided, and the first and second electrodes are provided. Preferably, the space between the electrode and the third electrode is evacuated. Also in this case, the electric field application unit may function as an actuator. As a result, the amount of emitted electrons can be controlled by the displacement operation.
Preferably, the power supply further includes a voltage source for applying a DC offset voltage to the third electrode, and a resistor arranged in series between the voltage source and the third electrode. Thereby, a desired current density can be easily achieved, and a short circuit between the third electrode and the first and second electrodes is prevented.
For example, a pulse voltage is applied to the first electrode, and a DC offset voltage is applied to the second electrode.
Preferably, the apparatus further comprises a capacitor arranged in series between the first electrode and a voltage signal source. Thus, a voltage can be applied between the first electrode and the second electrode only until the capacitor is filled, thereby preventing the first and second electrodes from being damaged by a short circuit.
When the electric field applying section further includes a fourth electrode formed on the other surface of the electric field applying section and corresponding to the first electrode, the electric field applying section between the first electrode and the fourth electrode functions as a capacitor. Therefore, breakage due to short circuit of the first and second electrodes is prevented. In this case, for example, a pulse voltage is applied to the fourth electrode, and a DC offset voltage is applied to the second electrode.
[0024] A resistor may be further provided in series between the second electrode and the DC offset voltage source. In this case, a current flowing from the first electrode to the second electrode by discharging is suppressed by the resistance, and damage due to short circuit of the first and second electrodes is prevented.
In order to greatly reduce the applied voltage, it is preferable that the relative permittivity of the electric field application section is 1000 or more and / or the width of the slit is 500 μm or less.
In order to emit electrons favorably, at least one of the first electrode and the second electrode has an acute angled corner, and / or the first electrode and the second electrode have an acute angle. It is preferable to have carbon nanotubes, that is, particles or aggregates of particles containing a carbon material having a six-carbon ring structure.
The field emission display according to the present invention comprises:
A plurality of two-dimensionally arranged electron-emitting devices;
A plurality of phosphors respectively arranged at predetermined intervals for these electron-emitting devices,
Each of the electron-emitting devices is
An electric field application unit composed of a dielectric,
A first electrode formed on one surface of the electric field application unit;
A second electrode formed on one surface of the electric field applying unit and forming a slit together with the first electrode.
According to the present invention, since the electron-emitting device has excellent straightness, crosstalk is reduced and the phosphor pitch can be reduced as compared with the case where a conventional electron-emitting device is provided. In addition, it is not necessary to provide a grid for preventing electrons from being incident on the adjacent phosphor. As a result, the field emission display according to the present invention is preferable from the viewpoint of improvement in resolution, miniaturization of the device, and cost reduction. Since electrons can be emitted even when the degree of vacuum inside the field emission display is relatively low, the emission of electrons can be maintained even if the degree of vacuum inside decreases due to excitation of a phosphor or the like. In addition, in the conventional field emission display, it is necessary to secure a relatively large vacuum space as a margin for maintaining electron emission against such a decrease in the degree of vacuum, and it is difficult to make the display thinner. . On the other hand, in the present invention, it is not necessary to secure a large vacuum space in advance in order to maintain the emission of electrons with a decrease in the degree of vacuum, so that the display can be made thinner.
In order to further reduce the voltage applied to the electron-emitting device, it is preferable that a conductive coating is applied to the first electrode, the second electrode and the slit. In this case, the conductive coating significantly reduces the risk of damage to the first and second electrodes due to collision of electrons and / or ions and heat generation.
More preferably, a first conductive coating provided on the first electrode;
The first coating portion further includes a second conductive coating portion provided on the second electrode in a non-contact state. In this case, a resistor is not included in the equivalent circuit between the first electrode and the second electrode, so that a DC cut capacitor is not required, and driving at a high voltage is not required. Voltage can be further reduced. Also in this case, the first and second conductive coatings significantly reduce the risk of damage to the first and second electrodes due to collision of electrons and / or ions and heat generation.
The slit may be provided with a high-resistance portion having a higher resistance than the first and second conductive coating portions and electrically contacting the first and second conductive coating portions. In this case, when a voltage is applied to the electron-emitting device, the voltage of the high resistance portion becomes higher than the voltages of the first and second conductive coating portions, and the concentration of the electric field in the high resistance portion, that is, the slit is improved. As a result, electrons can be emitted with a lower applied voltage than when no high-resistance portion is provided, power consumption is reduced, and cost is reduced by downsizing the circuit and omitting high-voltage compatible components. Can be.
In order to satisfactorily emit electrons, a third electrode is further provided at a predetermined distance from the first and second electrodes, and the first and second electrodes and the third electrode are provided. Preferably, the space between the three electrodes is evacuated.
Another field emission display according to the present invention is:
A plurality of two-dimensionally arranged electron-emitting devices;
A plurality of phosphors respectively arranged at predetermined intervals for these electron-emitting devices,
Each of the electron-emitting devices is
An electric field applying unit formed of at least one of a piezoelectric material, an electrostrictive material, and an antiferroelectric material,
A first electrode formed on one surface of the electric field application unit;
A second electrode formed on one surface of the electric field applying unit and forming a slit together with the first electrode.
According to the present invention, since the straightness of the electron-emitting device is further improved, the field emission display according to the present invention is more preferable from the viewpoint of miniaturization and cost reduction.
In order to further reduce the voltage applied to the electron-emitting device, it is preferable to apply a conductive coating to the first electrode, the second electrode and the slit. In this case, the conductive coating significantly reduces the risk of damage to the first and second electrodes due to collision of electrons and / or ions and heat generation.
[0036] More preferably, a first conductive coating portion provided on said first electrode;
The first coating portion further includes a second conductive coating portion provided on the second electrode in a non-contact state. In this case, a resistor is not included in the equivalent circuit between the first electrode and the second electrode, so that a DC cut capacitor is not required, and driving at a high voltage is not required. Voltage can be further reduced. Also in this case, the first and second conductive coatings significantly reduce the risk of damage to the first and second electrodes due to collision of electrons and / or ions and heat generation.
The slit may be provided with a high resistance portion having a higher resistance than the first and second conductive coating portions and electrically contacting the first and second conductive coating portions. In this case, when a voltage is applied to the electron-emitting device, the voltage of the high resistance portion becomes higher than the voltages of the first and second conductive coating portions, and the concentration of the electric field in the high resistance portion, that is, the slit is improved. As a result, electrons can be emitted with a lower applied voltage than when no high-resistance portion is provided, power consumption is reduced, and cost is reduced by downsizing the circuit and omitting high-voltage compatible components. Can be.
Also in this case, in order to satisfactorily emit electrons, a third electrode arranged at a predetermined distance from the first and second electrodes is further provided, and the first and second electrodes are provided. Preferably, the space between the electrode and the third electrode is evacuated. Also in this case, the electric field application unit may function as an actuator. As a result, the amount of emitted electrons can be controlled by the displacement operation.
Preferably, the power supply further includes a voltage source for applying a DC offset voltage to the third electrode, and a resistor arranged in series between the voltage source and the third electrode. Thereby, a desired current density, that is, a light emission amount of the phosphor can be easily achieved, and a short circuit between the third electrode and the first and second electrodes is prevented.
For example, a pulse voltage is applied to the first electrode, and a DC offset voltage is applied to the second electrode.
Preferably, the apparatus further comprises a capacitor arranged in series between the first electrode and a voltage signal source. This prevents breakage of the first and second electrodes due to short circuit.
In the case where a fourth electrode formed on the other surface of the electric field applying portion and corresponding to the first electrode is further provided, breakage of the first and second electrodes due to short circuit is prevented. In this case, for example, a pulse voltage is applied to the fourth electrode, and a DC offset voltage is applied to the second electrode.
In the case where a resistor is further arranged in series between the second electrode and the DC offset voltage source, breakage due to short circuit of the first and second electrodes is prevented.
In order to greatly reduce the applied voltage, it is preferable that the relative permittivity of the electric field application section is 1000 or more and / or the width of the slit is 500 μm or less.
In order to perform good electron emission, at least one of the first electrode and the second electrode has an acute angled corner, and / or the first electrode and the second electrode have an acute angle. It is preferred to have carbon nanotubes.
The field emission display according to the present invention further includes a substrate integrally formed with a plurality of two-dimensionally arranged electron-emitting devices.
[0047]
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an electron-emitting device according to the present invention and a field emission display using the same will be described in detail with reference to the drawings.
FIG. 1A is a top view of a first embodiment of the electron-emitting device according to the present invention, and FIG. 1B is a sectional view taken along line II of FIG. This electron-emitting device has an electric field applying portion 1 made of a dielectric, a driving electrode 2 as a first electrode formed on one surface thereof, and a slit formed together with the driving electrode 2 on the same surface. And a common electrode 3 as a second electrode to be formed on the substrate 4. Preferably, the electron-emitting device further includes an electron-capturing electrode 5 serving as a third electrode disposed at a predetermined distance from one surface of the electric field application unit 1 in order to capture the emitted electrons favorably. And a space between them is maintained in a vacuum state. In order to prevent breakage of the drive electrode 2 and the common electrode 3 due to a short circuit, a capacitor (not shown) is arranged in series between the drive electrode 2 and a voltage signal source (not shown), and / or a capacitor (not shown). A resistor (not shown) is arranged in series with a DC offset voltage source not shown. In FIG. 1A, the electron capture electrode 5 is omitted for clarity.
As the dielectric constituting the electric field applying section 1, a dielectric having a relatively high relative permittivity, for example, 1000 or more is preferably employed. Such dielectrics include, in addition to barium titanate, lead zirconate, lead magnesium niobate, lead nickel niobate, lead zinc niobate, lead manganese niobate, lead magnesium tantalate, lead nickel tantalate, Ceramics containing lead antimonate stannate, lead titanate, barium titanate, lead magnesium tungstate, lead cobalt niobate, etc. or any combination thereof; those containing 50% by weight or more of these compounds as main components; And the above-mentioned ceramics to which oxides of lanthanum, calcium, strontium, molybdenum, tungsten, barium, niobium, zinc, nickel, manganese, etc. or any combination thereof or other compounds are appropriately added. be able to. For example, in a binary nPMN-mPT of lead magnesium niobate (PMN) and lead titanate (PT) (where n and m are mole ratios), the Curie point increases as the mole ratio of PMN increases. It can be lowered to increase the relative dielectric constant at room temperature. In particular, when n = 0.85-1.0 and m = 1.0-n, the relative dielectric constant is preferably 3000 or more, which is preferable. For example, when n = 0.91 and m = 0.09, the relative dielectric constant at room temperature is 15000, and when n = 0.95 and m = 0.05, the relative dielectric constant at room temperature is 20,000. Next, in the three-component system of lead magnesium niobate (PMN), lead titanate (PT), and lead zirconate (PZ), besides increasing the molar ratio of PMN, tetragonal and pseudocubic or tetragonal In order to increase the relative dielectric constant, it is preferable to have a composition near a morphotropic phase boundary (MPB: Morphotropic Phase Boundary) between the rhombohedral and the rhombohedral crystal. For example, the relative dielectric constant is 5500 when PMN: PT: PZ = 0.375: 0.375: 0.25, and the relative dielectric constant is 4500 when PMN: PT: PZ = 0.5: 0.375: 0.125. Are particularly preferred. Further, it is preferable to improve the dielectric constant by mixing a metal such as platinum into these dielectrics as long as the insulating property can be ensured. In this case, for example, 20% by weight of platinum is mixed into the dielectric.
In the present embodiment, the drive electrode 2 has an acute angle. A pulse voltage is applied to the drive electrode 2 from a power source (not shown), and electrons are mainly emitted from the corners. In order to emit electrons well, the width Δ of the slit between the drive electrode 2 and the common electrode 3 is preferably set to 500 μm or less. The drive electrode 2 is made of a conductor having resistance to a high-temperature oxidizing atmosphere, for example, a metal simple substance, an alloy, a mixture of an insulating ceramic and a simple metal, a mixture of an insulating ceramic and an alloy, and the like. , Palladium, rhodium, molybdenum and other high-melting precious metals, alloys such as silver-palladium, silver-platinum and platinum-palladium as main components, and cermet materials of platinum and ceramic materials. More preferably, it is composed of a material mainly composed of platinum or a platinum-based alloy. In addition, carbon and graphite-based materials, for example, a diamond thin film, diamond-like carbon, and carbon nanotube are suitably used as the electrode. The ratio of the ceramic material added to the electrode material is preferably about 5 to 30% by volume.
In forming the drive electrode 2, the above materials are used to form various thick film forming methods such as screen printing, spraying, conductive coating, dipping, coating, electrophoresis, sputtering, ion beam, and vacuum deposition. , Ion plating, CVD, plating, etc., and can be formed according to an ordinary film forming method using various thin film forming methods, and preferably, these thick film forming methods are used.
When the drive electrode 2 is formed by a thick film forming technique, its thickness is generally 20 μm or less, preferably 5 μm or less.
A DC offset voltage is applied to the common electrode 3, and the common electrode 3 is drawn out as a wiring from the back surface of the substrate 4 through a through hole (not shown).
The common electrode 3 is formed by the same material and method as the drive electrode 2, but is preferably formed by the above-mentioned thick film forming method. The thickness of the common electrode 3 is also generally 20 μm or less, preferably 5 μm or less.
In order to electrically separate the wiring electrically connected to the drive electrode 2 from the wiring electrically connected to the common electrode 3, the substrate 4 is preferably made of an electrically insulating material.
Accordingly, the substrate 4 can be made of a metal having high heat resistance or a material such as an enamel whose metal surface is coated with a ceramic material such as glass, but is most preferably made of ceramics. .
As the ceramics constituting the substrate 4, for example, stabilized zirconium oxide, aluminum oxide, magnesium oxide, titanium oxide, spinel, mullite, aluminum nitride, silicon nitride, glass, a mixture thereof, or the like is used. Can be. Among them, aluminum oxide and stabilized zirconium oxide are preferable from the viewpoint of strength and rigidity. Stabilized zirconium oxide is particularly suitable from the viewpoint of relatively high mechanical strength, relatively high toughness, relatively small chemical reaction with the drive electrode 2 and the common electrode 3, and the like. Note that the stabilized zirconium oxide includes stabilized zirconium oxide and partially stabilized zirconium oxide. Since the stabilized zirconium oxide has a crystal structure such as a cubic crystal, no phase transition occurs.
On the other hand, zirconium oxide undergoes a phase transition between a monoclinic system and a tetragonal system at around 1000 ° C., and cracks may occur during such a phase transition. The stabilized zirconium oxide contains 1 to 30 mol% of a stabilizer such as calcium oxide, magnesium oxide, yttrium oxide, scandium oxide, ytterbium oxide, cerium oxide, or an oxide of a rare earth metal. In addition, in order to improve the mechanical strength of the substrate 4, it is preferable that the stabilizer contains yttrium oxide. In this case, the content of yttrium oxide is preferably 1.5-6 mol%, more preferably 2-4 mol%, and further preferably 0.1-5 mol% of aluminum oxide.
The crystal phase may be a mixed phase of cubic + monoclinic, a mixed phase of tetragonal + monoclinic, a mixed phase of cubic + tetragonal + monoclinic, and the like. The one in which the main crystal phase is a tetragonal or a mixed phase of tetragonal and cubic is most suitable from the viewpoint of strength, toughness and durability.
When the substrate 4 is made of ceramics, a relatively large number of crystal grains constitute the substrate 4. To improve the mechanical strength of the substrate 4, the average grain size of the crystal grains is preferably adjusted. The thickness is 0.05-2 μm, and more preferably 0.1-1 μm.
Each time the electric field applying unit 1, the driving electrode 2 and the common electrode 3 are formed, the electric field applying unit 1, the driving electrode 2 and the common electrode 3 can be integrated with the substrate 4. After the electrodes 3 are formed, they can be simultaneously heat-treated, that is, fired, and can be integrally bonded to the substrate 4 at the same time.
It should be noted that depending on the method of forming the drive electrode 2 and the common electrode 3, heat treatment for integration, that is, firing may not be required.
The heat treatment, that is, the firing temperature for integrating the substrate 4 with the electric field applying section 1, the driving electrode 2 and the common electrode 3 is generally in the range of 500 to 1400 ° C., preferably 1000 to 1400 ° C. Range. Further, in the case where the film-shaped voltage applying unit 1 is subjected to heat treatment, it is preferable to perform heat treatment, that is, sintering while controlling the atmosphere together with the evaporation source of the electric field applying unit 1 so that the composition of the electric field applying unit 1 does not become unstable at a high temperature. Preferably, a method is employed in which the electric field applying unit 1 is covered with an appropriate component, and firing is performed so that the surface of the electric field applying unit 1 is not directly exposed to the firing atmosphere. In this case, a material similar to that of the substrate 4 is used as a member to be covered.
FIG. 2A is a top view of a second embodiment of the electron-emitting device according to the present invention, and FIG. 2B is a sectional view taken along the line II-II. The electron-emitting device is formed on the other surface of the electric field applying unit 11 in addition to the electric field applying unit 11, the driving electrode 12, and the common electrode 13 corresponding to the electric field applying unit 1, the driving electrode 2, and the common electrode 3, respectively. It further has a drive terminal electrode 14 as a fourth electrode, and is formed on the substrate 15. Also in this case, preferably, the electron-emitting device preferably has an electron-capturing electrode as a third electrode arranged at a predetermined distance from one surface of the electric field applying unit 1 in order to capture the emitted electrons favorably. It further has 16 and maintains the space between them in a vacuum state. Also in FIG. 2A, the electron capture electrode 16 is omitted for clarity.
In the present embodiment, since the electric field applying portion 11 between the drive electrode 12 and the drive terminal electrode 14 functions as a capacitor, a capacitor is provided to prevent the drive electrode 12 and the common electrode 13 from being damaged due to a short circuit. Need not be provided separately. In this case, a pulse voltage is applied to the drive terminal electrode 14 and a DC offset voltage is applied to the common electrode 13.
The drive terminal electrode 14 is also formed by the same material and method as the drive electrode 12 and the common electrode 13, but is preferably formed by the above-mentioned thick film formation method. The thickness of the drive terminal electrode 14 is also generally 20 μm or less, preferably 5 μm or less.
FIG. 3A is a top view of an electron-emitting device according to a third embodiment of the present invention, and FIG. 3B is a sectional view taken along line III-III of FIG. In the present embodiment, the drive electrode 22 and the common electrode 23 are formed on one surface of the electric field application unit 21 as in the first embodiment. When a pulse voltage is applied to the drive electrode 22 and a DC offset voltage is applied to the common electrode 23, electrons are easily emitted from the tip of the CNT.
FIG. 4A is a top view of a fourth embodiment of the electron-emitting device according to the present invention, and FIG. 4B is a sectional view taken along the line IV-IV. In the present embodiment, similarly to the second embodiment, the drive electrode 32 and the common electrode 33 are formed on one surface of the electric field application unit 31, and the drive terminal electrode 34 is formed on the other surface. However, a plurality of carbon nanotubes (CNT) are provided on the surfaces of the drive electrode 32 and the common electrode 33, whereby a pulse voltage is applied to the drive terminal electrode 33 and a DC offset voltage is applied to the common electrode 33. Is applied, electrons are easily emitted from the tip of the CNT.
FIG. 5A is a top view of a fifth embodiment of the electron-emitting device according to the present invention, and FIG. 5B is a sectional view taken along line VV. In the present embodiment, a comb-shaped drive electrode 42 and a common electrode 43 are formed on one surface of the electric field application unit 41. In this case, when a pulse voltage is applied to the drive electrode 42 and a DC offset voltage is applied to the common electrode 43, electrons are easily emitted from the corners of the drive electrode 42 and the common electrode 43.
FIG. 6A is a top view of a sixth embodiment of the electron-emitting device according to the present invention, and FIG. 6B is a sectional view taken along line VI-VI of FIG. In the present embodiment, the electron-emitting device includes electric field applying portions 51a and 51b made of an antiferroelectric material, and comb-shaped driving electrodes 52a and 52b and common electrodes 53a and 53b formed on one surface thereof. Having.
The electron-emitting device is arranged on a sheet layer 56 provided on a substrate 55 via a spacer layer 54. Thus, the electric field applying units 51a and 51b, the drive electrodes 52a and 52b, the common electrodes 53a and 53b, the sheet layer 56, and the spacer layer 54 form actuators 57a and 57b, respectively.
Examples of the antiferroelectric material constituting the electric field applying portions 51a and 51b include those mainly composed of lead zirconate, those mainly composed of components consisting of lead zirconate and lead stannate, and those of lead zirconate. It is preferable to use lanthanum oxide attached thereto, or a mixture of lead zirconate and lead stannate to which lead zirconate or lead niobate is added. In particular, when driven at a low voltage, it is preferable to use an antiferroelectric material containing a component consisting of lead zirconate and lead stannate. This composition is as follows.
PB_0.99Nb_0.02[(Zr_xSn_1-x)_1-yTi_y]_0.98O₃
Further, the antiferroelectric material can be made porous. In this case, the porosity is preferably set to 30% or less.
In forming the electric field applying portions 51a and 51b, it is preferable to use the above thick film forming method, and the screen printing method is particularly preferable because fine printing can be performed at low cost. Used for The screen printing method is particularly preferably used as the thickness of the electric field applying portions 51a and 51b, for example, because a large displacement is obtained at a low operating voltage. The thickness of the electric field applying portions 51a and 51b is preferably 50 μm or less, and more preferably 3 to 40 μm, because a large displacement is obtained at a low operating voltage.
According to such a thick film forming method, a paste or a slurry mainly containing ceramic particles of an antiferroelectric material having an average particle diameter of about 0.01 to 7 μm, preferably about 0.05 to 5 μm is used. Thus, a film can be formed on the surface of the sheet layer 56, and good element characteristics can be obtained.
In the electrophoresis method, a film can be formed with high density and high shape control, and it can be formed by a technical document “DENKI KAGAKU 53, No. 1 (1985), pp. 63-68 Kazuo Anzai” or “First Electrophoresis Method”. High-order forming method of ceramics according to {Research Symposium} Preliminary Collection (1998), p5-6.p23-24 ”. Therefore, it is preferable to appropriately select and use various methods in consideration of required accuracy, reliability, and the like.
The sheet layer 56 is formed to be relatively thin, and has a structure that is easily affected by external stress. The sheet layer 56 is preferably made of a highly heat-resistant material. The reason for this is that, as shown in FIGS. 2 and 4, when the drive terminal electrodes are directly joined to the sheet layer 56, a structure that directly supports the sheet layer 56 without using a material having a relatively low heat resistance such as an organic adhesive is used. This is to prevent the sheet layer 56 from being deteriorated at least when the electric field applying portions 51a and 51b are formed. When the sheet layer 56 is formed of ceramics, the sheet layer 56 is formed similarly to the substrate 4 of FIG.
Although the spacer layer 54 is preferably made of ceramics, it can be made of the same ceramic material as that of the sheet layer 56 or a different ceramic material. Examples of such ceramics include, similarly to the ceramic material constituting the sheet layer 56, for example, stabilized zirconium oxide, aluminum oxide, magnesium oxide, titanium oxide, spinel, mullite, aluminum nitride, silicon nitride, glass, And the like can be used.
The ceramic material different from the ceramic material forming the spacer layer 54, the substrate 55, and the sheet layer 56 includes a material containing zirconium oxide as a main component, a material containing aluminum oxide as a main component, and a mixture thereof. The material to be used is preferably adopted. Among them, those containing zirconium oxide as a main component are particularly preferable. In addition, clay or the like may be attached as a sintering aid, but it is necessary to adjust the auxiliary component so that an easily vitrified material such as silicon oxide or boron oxide is not included. The reason is that these easily vitrified materials are advantageous from the viewpoint of joining with the electric field applying parts 51a and 51b, but promote the reaction with the electric field applying parts 51a and 51b, and the electric field applying parts 51a and 51b Is difficult to maintain, and as a result, the device characteristics are degraded.
That is, it is preferable that the silicon oxide and the like contained in the spacer layer 54, the substrate 55 and the sheet layer 56 be limited to 3% by weight or less, preferably 1% or less. Here, the main component refers to a component that exists at a ratio of 50% or more by weight.
It is preferable that the spacer layer 54, the substrate 55, and the sheet layer 56 are formed as a three-layered laminated body. In this case, for example, the respective layers are integrally and simultaneously fired, or the respective layers are joined or integrated with glass or resin. . In addition, it can also be set as a laminated body of four or more layers.
When the electric field applying units 51a and 51b are made of an antiferroelectric material as in the present embodiment, when no electric field is applied, the electric field applying units 51a and 51b become flat like the electric field applying unit 51b. When an electric field is applied, it is bent and displaced in a convex shape like the electric field application section 51a. Since the gap between the electron-emitting device and the electron-capturing electrode 58 facing the electron-emitting device is narrowed by the convex bending displacement, the straightness of the generated electrons is further improved as indicated by the arrow. . Therefore, the amount of emitted electrons reaching the electron capture electrode 58 can be controlled by using the amount of bending displacement.
Next, the operation of the electron-emitting device according to the present invention will be described.
FIG. 7 is a diagram for explaining the operation of the electron-emitting device according to the present invention. In this case, the current control element 61 has the configuration shown in FIG. 1, and its periphery is held in a vacuum state by the vacuum chamber 62. In order to prevent a short circuit between the drive electrode 63 and the common electrode 64, a capacitor 66 is arranged between the drive electrode 63 and the voltage signal source 65 in series. A bias voltage Vb is applied to the electron capture electrode 67 facing the drive electrode 63 and the common electrode 64.
Voltage V applied to signal voltage source 65₁Is set to −400 V, the capacitance of the capacitor 66 is set to 500 pF, the bias voltage Vb is set to 0 V, the width of the slit formed by the driving electrode 63 and the common electrode 64 is set to 10 μm, and the degree of vacuum inside the vacuum chamber 62 is set to 1 × 10^-3When Pa, the current I flowing through the drive electrode 63₁Is 2.0 A, and the density of the collector current Ic taken out from the electron capture electrode 67 is 1.2 A / cm.²It becomes. As a result, according to the electron-emitting device of the present invention, a higher current density can be obtained at a lower voltage and a lower degree of vacuum as compared with the conventional electron-emitting device, and as a result, excellent straightness is exhibited. As shown in FIG. 7B, the collector current Ic increases as the bias voltage Vb increases.
FIG. 8 is a diagram for explaining the operation of another electron-emitting device according to the present invention. In this case, the current control element 71 has the configuration shown in FIG. 2, and its periphery is held in a vacuum state by the vacuum chamber 72. Further, in order to prevent a short circuit between the drive electrode 73 and the common electrode 74, the electric field application section 76 between the drive electrode 73 and the drive terminal electrode 75 plays a role of a capacitor. The electron capture electrode 77 faces the drive electrode 73 and the common electrode 74.
Voltage V applied to signal voltage source 78₁Is set to −400 V, the electric field applying unit 76 serves as a capacitor having a capacitance of 530 pF, the width of the slit formed by the driving electrode 73 and the common electrode 74 is 10 μm, and the degree of vacuum inside the vacuum chamber 72 is 1 ×. 10^-3とした Pa, the current I flowing through the drive terminal electrode 75₁Is 2.0 A, and the density of the collector current Ic taken out from the electron capture electrode 77 is 1.2 A / cm.²It becomes. As a result, according to the other electron-emitting device of the present invention, a higher current density can be obtained at a lower voltage and a lower degree of vacuum as compared with the conventional electron-emitting device, and as a result, excellent straightness can be obtained. Note that the voltage V₁, Current Ic, I₁, I₂The waveforms of are shown by curves ad in FIG. 8B, respectively.
FIG. 9 is a diagram showing an embodiment of the FED according to the present invention. The FED includes a plurality of two-dimensionally arrayed electron-emitting devices 81R, 81G, and 81B, and a red phosphor 82R disposed at a predetermined distance from each of the electron-emitting devices 81R, 81G, and 81B. A green phosphor 82G and a blue phosphor 82B are provided.
In this embodiment, the electron-emitting devices 81 R, 81 G, and 81 B are formed on the substrate 83, and the red phosphor 82 R, the green phosphor 82 G, and the blue phosphor 82 B are formed on the glass substrate 85 via the electron capture electrodes 84. It is formed. Each of the electron-emitting devices 81R, 81G, and 81B has the structure shown in FIG. 2, but may have any of the structures shown in FIGS.
According to the present embodiment, since the electron-emitting devices 81R, 81G, and 81B are excellent in straightness, crosstalk is reduced as compared with the case where a conventional electron-emitting device is provided, and the phosphors 82R and 82G are formed. , 82B can be narrowed, and there is no need to provide a grid in order to prevent electrons from being incident on the adjacent phosphors 82R, 82G, 82B. As a result, the FED of the present embodiment is preferable from the viewpoint of miniaturization and cost reduction. Since electrons can be emitted even when the degree of vacuum is relatively low, there is no need to enlarge the vacuum space in advance to look at a margin for a decrease in the degree of vacuum, and the restrictions on thinning the FED are reduced.
FIG. 10 is a diagram showing the relationship between the relative permittivity of the electron-emitting device according to the present invention and the applied voltage, and FIG. 11 is a diagram for explaining the relationship. The characteristics shown in FIG. 10 show the relative permittivity of the electric field application unit when the widths d1 and d2 of the slits formed by the drive electrode 91 and the common electrodes 92a to 92c are both 10 μm, as shown in FIG. FIG. 6 is a diagram showing a relationship with an applied voltage necessary for emission of helium.
As shown in FIG. 10, when the electron-emitting device is driven using a lower applied voltage than the conventional electron-emitting device, it is understood that the relative dielectric constant is preferably set to 1000 or more.
FIG. 12 is a diagram showing the relationship between the slit width and the applied voltage of the electron-emitting device according to the present invention. From FIG. 12, it is understood that the slit width needs to be 500 μm or less in order for the electron emission phenomenon to occur. In order to drive the electron-emitting device according to the present invention with a driver IC used in a commercially available plasma display, fluorescent display tube, or liquid crystal display, the slit width needs to be 20 μm or less.
FIG. 13A is a top view of an electron-emitting device according to a seventh embodiment of the present invention, and FIG. 13B is a sectional view taken along line VII-VII of FIG. In the present embodiment, a drive electrode 102 and a common electrode 103 having a semicircular shape are formed on one side of the electric field application unit 101, and a conductive coating unit 104 is formed on the drive electrode 102, the common electrode 103, and the slit formed by these. Is provided.
The operation of the electron-emitting device having the structure shown in FIG. 13 will be described with reference to FIG. In this case, the periphery of the current emitting element is kept in a vacuum state by the vacuum chamber 111. In order to prevent a short circuit between the drive electrode 102 and the common electrode 103, a capacitor 113 is arranged between the drive electrode 102 and the voltage signal source 112 in series. A phosphor 115 is provided on the electron capture electrode 114 facing the drive electrode 102 and the common electrode 103, and a bias voltage Vb is applied.
The driving electrode 102 and the common electrode 103 are made of Au having a thickness of 3 μm. The conductive coating 104 made of carbon (thickness of 3 μm) is applied to the driving electrode 102 and the common electrode 103 and the slit therebetween. ). The pulse voltage Vk applied to the signal voltage source 112 is set to 25 V, the capacitance of the capacitor 113 is set to 5 nF, the bias voltage Vb is set to 300 V, and the electric field applying unit 101 is made of an electrostrictive material having a relative dielectric constant of 14000. The width of the slit formed by the electrode 102 and the common electrode 103 is 10 μm, and the degree of vacuum inside the vacuum chamber 111 is 1 × 10^-3When Pa, the current Ic flowing through the electron capture electrode 114 is 0.1 A, and the current Ic flowing through the drive electrode 102 is₁About 40% of the current with respect to (0.25 A) is extracted as an electron current, and the voltage Vs between the driving electrode 102 and the common electrode 103, that is, the voltage required for emitting electrons becomes 23.8 V. . As a result, according to the electron-emitting device shown in FIG. 13, the voltage required for emitting electrons can be significantly reduced. In addition, the possibility that the drive electrode 102 and the common electrode 103 are damaged by collision of electrons or ions or heat generation is significantly reduced by the conductive coating portion 104. The current I flowing through the drive electrode 102₁電流, current I flowing through common electrode 103₂The waveforms of, Ic and voltage Vs are shown by curves eh in FIG. 14B, respectively.
The conductive coating portion 104 functions as a protective film for the drive electrode 102 and / or the common electrode 103. Specifically, collision of ions or electrons generated near the slit portion at the time of electron emission and accelerated by an applied voltage, and damage of the drive electrode 102 and / or the common electrode 103 due to the accompanying heat generation are prevented. From this viewpoint, the conductive coating 104 is preferably made of a material having a low sputtering rate and a high melting point.
In addition to the carbon, the conductive coating portion 104 may be a conductor having resistance to a high-temperature oxidizing atmosphere, for example, a metal simple substance, an alloy, a mixture of an insulating ceramic and a simple metal, an insulating ceramic and an alloy. Preferably, a high melting point noble metal such as platinum, palladium, rhodium, and molybdenum, silver-palladium, silver-platinum, those containing an alloy such as platinum-palladium as a main component, or platinum and It is composed of a cermet material with a ceramic material. More preferably, it is composed of a material mainly composed of platinum or a platinum-based alloy. Further, as the conductive coating portion 104, a graphite-based material, for example, a diamond thin film, diamond-like carbon, or carbon nanotube is preferably used. The ratio of the ceramic material added to the conductive coating material is preferably about 5 to 30% by volume. It is preferable that the resistance value of the conductive coating portion 104 be, for example, several kilo ohms to 100 kilo ohms. The conductive coating portion 104 is formed of vapor-deposited carbon (for example, “Carbon 5PC” manufactured by Sanyu Industry Co., Ltd.), imprinted carbon (for example, “FW200” manufactured by Degussa, etc.), printed carbon, or the like. I do. Further, a conductive film covered with a thin film of an oxide of an alkali metal or an alkaline earth metal, particularly, a magnesium oxide is also preferably used as the conductive coating portion 104.
FIG. 15A is a top view of an eighth embodiment of the electron-emitting device according to the present invention, and FIG. 15B is a sectional view taken along line VIII-VIII of FIG. In the present embodiment, a drive electrode 112 and a common electrode 113 having a semicircular shape are formed on one side of the electric field application unit 111, and a conductive coating portion 114 a is formed on the drive electrode 112, and a conductive electrode is formed on the common electrode 113. The conductive coating portion 114b is formed in a non-contact state with the conductive coating portion 114a.
In such an electron-emitting device, the drive electrode 122 and the common electrode 123 are formed on one side of the electric field application section 121 by printing, and then the drive electrode 122, the common electrode 123, and the slit 124 formed by these are formed. Then, a coating portion 125 is formed by carbon vapor deposition of a conductive material (FIG. 16A), and a laser beam 127 is irradiated from a laser irradiation source 126 to the slit 124 (FIG. 16B), and the conductive coating portion 125a and the It is obtained by forming the non-contact conductive coating portion 125b. After forming the driving electrode 122 and the common electrode 123 on one side of the electric field applying unit 121 by printing, by printing the conductive coating portion 125a and the conductive coating portion 125b in a non-contact state with the conductive coating portion 125a, FIG. Can be obtained. Further, by applying a thin film technique such as photolithography, an electron-emitting device having a structure shown in FIG. 16C can be obtained.
According to the eighth embodiment of the electron-emitting device according to the present invention, the first conductive coating portion and the second conductive coating portion in a non-contact state with the first conductive coating portion cause collision of electrons or ions and heat generation. The risk of damage to the drive electrode and the common electrode due to the above is significantly reduced, and the drive voltage when the electron-emitting device is used in the drive circuit is greatly reduced. Such a drastic reduction in drive voltage will be described in detail. When the electron-emitting device according to the seventh embodiment is arranged on a zirconia substrate 131, the drive electrode 132 is connected to a signal voltage source 133 that generates a pulse signal, and the common electrode 134 is grounded (FIG. 17A). ), An equivalent circuit a between the drive electrode 132 and the common electrode 134 has a resistor a1 and a capacitor a2 connected in parallel to the resistor a1 (FIG. 17B). In order to prevent DC from flowing through the resistor a1, a DC cut capacitor 135 is provided between the signal voltage source 133 and the electron-emitting device. On the other hand, the electron-emitting device according to the eighth embodiment is arranged on a zirconia substrate 141, the drive electrode 142 is connected to a signal voltage source 143 that generates a pulse signal, and the common electrode 144 is grounded. In this case (FIG. 17C), the equivalent circuit b between the drive electrode 142 and the common electrode 144 has only the capacitor b1 (FIG. 17D). Since the equivalent circuit b has no resistance, it is not necessary to provide a DC cut capacitor between the signal voltage source 143 and the electron-emitting device. Since the drive voltage is no longer divided by the DC cut capacitor, the drive voltage when used in the drive circuit is greatly reduced as compared with the above-described seventh embodiment, and drive at a high voltage is unnecessary. As a result, the circuit can be configured at a low cost.
FIG. 18A is a top view of a ninth embodiment of the electron-emitting device according to the present invention, and FIG. 18B is a sectional view taken along the line IX-IX. In the present embodiment, a semicircular drive electrode 202 and a common electrode 203 are formed on one side of the electric field application unit 201, and a conductive coating 204a is formed on the drive electrode 202. The conductive coating portion 204b is formed in a non-contact state with the conductive coating portion 204a. In addition, a high-resistance portion 205 made of a material having a higher resistivity than the conductive coating portions 204a and 204b and electrically contacting the conductive coating portions 204a and 204b is formed by the drive electrode 202 and the common electrode 203. In the slit.
As shown in FIG. 18C, an equivalent circuit between the drive electrode 202 and the common electrode 203 includes the drive electrode 202, the conductive coating 204a, the high-resistance section 205, the conductive coating 204b, and the common electrode 203. Each has a corresponding terminal x1, resistors x2, x3, x4, and terminal x5. When a voltage is applied to the electron-emitting device, the voltage of the high resistance portion 205 becomes higher than the voltages of the conductive coating portions 204a and 204b, and the concentration of the electric field in the high resistance portion 205, that is, the slit is improved. As a result, electrons can be emitted at a low applied voltage, the power consumption can be reduced, and the cost can be reduced by downsizing the circuit and omitting high-voltage compatible components.
FIG. 19 is a view showing a modification of the electron-emitting device of FIG. In FIGS. 19A and 19B, a high-resistance portion formed of a material having higher resistivity than two conductive coating portions that do not contact each other and electrically contacting these conductive coating portions is formed by a driving electrode and a common electrode. Is provided in the slit. In FIG. 19C, a high-resistance portion which is made of the same material as the two conductive coating portions that do not contact each other, is in electrical contact with these conductive coating portions, and is thinner than these conductive coating portions is driven. It is provided in the slit formed by the electrode and the common electrode. Such a high-resistance portion, for example, irradiates the conductive coating portion on the slit with a laser to form a conductive coating portion thinner than the conductive coating portion formed on the drive electrode and the common electrode. Is obtained by
FIG. 20 is a diagram showing a tenth embodiment of the electron-emitting device according to the present invention. In this embodiment mode, the electron-emitting device is provided on a zirconium oxide (zirconia) substrate. For example, the electron-emitting device shown in FIG. 13 (FIG. 20A) and the electron-emitting device shown in FIG. The emission element (FIG. 20B), the electron emission element shown in FIG. 18 (FIG. 20C), the electron emission element shown in FIG. 19A (FIG. 20D), the electron emission element shown in FIG. 19B (FIG. 20E), and the electron emission element shown in FIG. (FIG. 20F) is arranged. As described above, it is preferable that the substrate is made of zirconium oxide from the viewpoints of strength, toughness, and durability.
FIG. 21A is a top view of an eleventh embodiment of the electron-emitting device according to the present invention, and FIG. 21B is a sectional view taken along line XX. In this embodiment mode, a driving electrode 302 and a common electrode 303 having a semicircular shape are formed on one side of the electric field application unit 301.
Referring to FIG. 22, the case where the electron-emitting device having the structure shown in FIG. 21 emits electrons at a low degree of vacuum of 200 Pa or less even without a conductive coating will be described with reference to FIG. In this case, the periphery of the current emitting element is maintained in a vacuum state by the vacuum chamber 311. In order to prevent a short circuit between the drive electrode 302 and the common electrode 303, a capacitor 213 is arranged between the drive electrode 302 and the voltage signal source 212 in series. A phosphor 315 is provided on the electron capture electrode 314 facing the drive electrode 302 and the common electrode 303, and a bias voltage Vb is applied.
The material of the drive electrode 302 and the common electrode 303 are both Au, the pulse voltage Vk applied to the signal voltage source 312 is 160 V, the capacitance of the capacitor 313 is 5 nF, the bias voltage Vb is 300 V, and the electric field is applied. When the portion 301 is made of an electrostrictive material having a relative dielectric constant of 4500, the width of the slit formed by the drive electrode 302 and the common electrode 303 is 10 μm, and the degree of vacuum inside the vacuum chamber 311 is 200 Pa or less. The current Ic flowing through the electron capture electrode 314 is 1.2 A, and the current Ic flowing through the driving electrode 302 is 1.2 A.₁Approximately 60% of the current with respect to (2A) is extracted as an electron current, and the voltage Vs between the drive electrode 302 and the common electrode 303, that is, the voltage required for electron emission is 153V. Note that the current I₁, I₂The waveforms of, Ic and the voltage Vs are shown by a curve i-l in FIG. 22B.
As described above, sufficient electron emission is possible at a very low degree of vacuum of 200 Pa or less even in the case where the conductive coating portion is provided.
According to the electron-emitting device of the present invention, electrons can be emitted at a very low degree of vacuum of 200 Pa or less. Therefore, when forming an FED, the sealing space at the outer peripheral portion of the panel must be made very small. Therefore, a narrow frame panel can be realized. Further, when the display is enlarged by arranging a plurality of panels, the seams between the panels are less noticeable. Furthermore, in the conventional FED, the degree of vacuum in the internal space of the FED due to gas generated from a phosphor or the like may be reduced, which may adversely affect the durability of the panel. According to this, electrons can be emitted at a very low degree of vacuum of 200 Pa or less, so that adverse effects due to a decrease in the degree of vacuum in the internal space of the FED are greatly reduced, and the durability and reliability of the panel are greatly improved. .
According to the electron-emitting device and the FED using the same according to the present invention, the size and the size of the electron-emitting device can be made simpler and smaller than in the prior art. More specifically, first, since the degree of vacuum in the internal space of the FED can be reduced, the structure for maintaining the housing against an internal / external pressure difference such as the outer peripheral sealing portion of the FED can be simplified and reduced in size. it can.
Further, since the applied voltage necessary for emitting electrons and the bias voltage to be applied to the electron capture electrode can be made relatively low, it is not necessary for the FED to have a withstand voltage structure, and the entire device can be miniaturized. In addition, the thickness of the panel can be reduced. Note that the bias voltage to be applied to the electron capture electrode may be 0V.
Further, when forming the electric field applying portion of the electron-emitting device according to the present invention, special processing is not required unlike the case of forming the Spindt-type electron-emitting device, and the electrodes and the electric field applying portion are made thicker. Since it can be formed by film printing, the electron-emitting device according to the present invention and the FED using the same can be manufactured at lower cost than before.
Furthermore, since the applied voltage necessary for emitting electrons and the bias voltage to be applied to the electron capture electrode can be made relatively low, a small and inexpensive drive IC having a relatively small withstand voltage must be used. Therefore, an FED using the field emission device according to the present invention can be manufactured at low cost.
The present invention is not limited to the above-described embodiment, and many modifications and variations are possible.
For example, the electron-emitting device according to the present invention can be applied to other applications such as a backlight. Since the electron-emitting device according to the present invention can emit a relatively large amount of electron beams at a relatively low voltage, a small-sized and high-efficiency sterilizer can be used in place of the conventional sterilizer which mainly uses an ultraviolet radiation system. It is suitable for constituting. Further, the electron-emitting device according to the present invention can employ any other electrode structure having a corner. Furthermore, in order to prevent a short circuit between the drive electrode and the common electrode, a resistor may be arranged in series between the second electrode, that is, the common electrode and the DC offset voltage source.
In the sixth embodiment, the case where the electric field applying units 51a and 51b are made of an anti-dielectric material has been described, but the electric field applying units 51a and 51b are made of a piezoelectric material, an electrostrictive material and an anti-dielectric material. May be constituted by at least one of the following. When a piezoelectric material and / or an electrostrictive material is used, for example, a material mainly containing lead zirconate (PZ), a material mainly containing lead nickel niobate, a material mainly containing lead zinc niobate, Lead manganese niobate-based material, lead magnesium tantalate-based material, nickel nickel tantalate-based material, lead antimonate-based material, lead titanate-based material , A material containing lead magnesium tungstate as a main component, a material containing lead cobalt niobate as a main component, or a composite material containing any combination thereof can be used. Of these, lead zirconate is used. The contained ceramic is most frequently used as a piezoelectric material and / or an electrostrictive material.
When the piezoelectric material and / or the electrostrictive material are ceramics, lanthanum, barium, niobium, zinc, cerium, cadmium, chromium, cobalt, antimony, iron, yttrium, tantalum, tungsten, nickel, manganese , Lithium, strontium, oxides such as bismuth or any combination thereof or any other compound as an appropriate material, for example, a material obtained by adding a predetermined additive to the material so as to be a PLZT-based material It is preferably used.
Among these piezoelectric materials and / or electrostrictive materials, a material mainly composed of a component composed of lead magnesium niobate, lead zirconate and lead titanate, lead nickel niobate, lead magnesium niobate and zirconate A material mainly composed of lead and lead titanate, a material mainly composed of lead magnesium niobate, lead nickel tantalate, lead zirconate and lead titanate, lead magnesium tantalate and magnesium A material mainly composed of a component consisting of lead niobate, lead zirconate and lead titanate, and a material obtained by substituting a part of lead of these materials with strontium and / or lanthanum are preferably used. It is suitable as a material when forming the electric field applying portions 51a and 51b by a thick film forming technique such as the above.
In the case of a multi-component piezoelectric material and / or an electrostrictive material, the piezoelectric and / or electrostrictive characteristics change depending on the composition of the components. However, lead magnesium niobate preferably employed in the sixth embodiment is used. -Three-component materials of lead zirconate-lead titanate, and four-component materials of lead magnesium niobate-lead nickel tantalate-lead titanate and lead magnesium tantalate-lead magnesium niobate-lead zirconate-lead titanate The material preferably has a composition near the phase boundary of pseudo-cubic-tetragonal-rhombohedral. Particularly, lead magnesium niobate: 15-50 mol%, lead zirconate: 10-45 mol%, lead titanate: 30 Composition of -45 mol%, lead magnesium niobate: 15-50 mol%, lead nickel tantalate: 10-40 mol%, lead zirconate: 10-45 mol%, lead titanate: 3 Composition of -45 mol% and composition of lead magnesium niobate: 15-50 mol%, lead magnesium tantalate: 10-40 mol%, lead zirconate: 10-45 mol%, lead titanate: 30-45 mol% Is preferably adopted because it has a high piezoelectric constant and a term electromechanical coupling coefficient.
In the ninth embodiment, the high-resistance portion is formed of a conductive material having a sparse distribution, a conductive material having a structure changed by locally breaking, deforming or altering the conductive material, a conductive material having a sparse distribution. Processed by applying high voltage, etc., to the conductive coating to locally destroy, deform or alter the conductive material, resulting in structural changes or micro cracks, only when an electric field is applied by the piezoelectric effect The slit may be expanded and the resistance value may be increased accordingly, or the slit may be minutely cracked by the piezoelectric effect and the resistance value may be increased accordingly. If the slit expands only when an electric field is applied due to the piezoelectric effect, and the resistance value is increased accordingly, there is an advantage that the pretreatment at the time of manufacturing can be omitted.
[Brief description of the drawings]
FIG. 1 is a diagram showing a first embodiment of an electron-emitting device according to the present invention.
FIG. 2 is a view showing a second embodiment of the electron-emitting device according to the present invention.
FIG. 3 is a view showing a third embodiment of the electron-emitting device according to the present invention.
FIG. 4 is a view showing a fourth embodiment of the electron-emitting device according to the present invention.
FIG. 5 is a diagram showing a fifth embodiment of the electron-emitting device according to the present invention.
FIG. 6 is a view showing a sixth embodiment of the electron-emitting device according to the present invention.
FIG. 7 is a diagram for explaining the operation of the electron-emitting device according to the present invention.
FIG. 8 is a diagram for explaining the operation of another electron-emitting device according to the present invention.
FIG. 9 is a diagram showing an embodiment of an FED according to the present invention.
FIG. 10 is a diagram showing a relationship between a relative dielectric constant of an electron-emitting device according to the present invention and an applied voltage.
FIG. 11 is a diagram for explaining FIG. 10;
FIG. 12 is a diagram showing a relationship between a slit width and an applied voltage of the electron-emitting device according to the present invention.
FIG. 13 is a view showing a seventh embodiment of the electron-emitting device according to the present invention.
FIG. 14 is a diagram for explaining the operation of the electron-emitting device of FIG.
FIG. 15 is a view showing an eighth embodiment of the electron-emitting device according to the present invention.
16 is a diagram for explaining the manufacture of the electron-emitting device of FIG.
FIG. 17 is a diagram for explaining an effect of the electron-emitting device of FIG.
FIG. 18 is a view showing a ninth embodiment of the electron-emitting device according to the present invention.
FIG. 19 is a view showing a modification of the electron-emitting device of FIG. 18;
FIG. 20 is a view showing an electron-emitting device according to a tenth embodiment of the present invention.
FIG. 21 is a view showing an eleventh embodiment of the electron-emitting device according to the present invention.
FIG. 22 is a diagram for explaining the operation of the electron-emitting device of FIG. 21.

Claims

An electric field application unit formed of a dielectric,
A first electrode formed on one surface of the electric field application unit;
An electron-emitting device, comprising: a second electrode formed on one surface of the electric field application unit and forming a slit together with the first electrode.

The electron-emitting device according to claim 1,
A third electrode disposed at a predetermined distance from the first and second electrodes;
An electron-emitting device, wherein a space between the first and second electrodes and the third electrode is evacuated.

The electron-emitting device according to claim 2,
A voltage source for applying a DC offset voltage to the third electrode;
An electron-emitting device further comprising a resistor arranged in series between the voltage source and the third electrode.

The electron-emitting device according to claim 1,
An electron-emitting device further comprising a conductive coating provided on the first electrode, the second electrode, and the slit.

The electron-emitting device according to claim 4,
A third electrode disposed at a predetermined distance from the first and second electrodes;
An electron-emitting device, wherein a space between the first and second electrodes and the third electrode is evacuated.

The electron-emitting device according to claim 5,
A voltage source for applying a DC offset voltage to the third electrode;
An electron-emitting device further comprising a resistor arranged in series between the voltage source and the third electrode.

The electron-emitting device according to claim 1,
A first conductive coating portion provided on the first electrode;
An electron-emitting device, further comprising a second conductive coating portion provided on the second electrode in a non-contact state with the first coating portion.

The electron-emitting device according to claim 7,
The electronic device according to claim 1, wherein a high resistance portion having a higher resistance than the first and second conductive coating portions and electrically contacting the first and second conductive coating portions is provided in the slit. Emission element.

The electron-emitting device according to claim 7,
A third electrode disposed at a predetermined distance from the first and second electrodes;
An electron-emitting device, wherein a space between the first and second electrodes and the third electrode is evacuated.

The electron-emitting device according to claim 9,
A voltage source for applying a DC offset voltage to the third electrode;
An electron-emitting device further comprising a resistor arranged in series between the voltage source and the third electrode.

The electron-emitting device according to claim 1,
An electron-emitting device, wherein a pulse voltage is applied to the first electrode and a DC offset voltage is applied to the second electrode.

The electron-emitting device according to claim 1,
An electron-emitting device, further comprising a capacitor arranged in series between the first electrode and a voltage signal source.

The electron-emitting device according to claim 1,
The electron-emitting device according to claim 1, further comprising a fourth electrode formed on the other surface of the electric field applying unit and corresponding to the first electrode.

The electron-emitting device according to claim 13,
An electron-emitting device, wherein a pulse voltage is applied to the fourth electrode and a DC offset voltage is applied to the second electrode.

The electron-emitting device according to claim 1,
An electron-emitting device further comprising a resistor arranged in series between the second electrode and a DC offset voltage source.

The electron-emitting device according to claim 1,
An electron-emitting device, wherein a relative dielectric constant of the electric field application unit is 1000 or more.

The electron-emitting device according to claim 1,
An electron-emitting device, wherein the width of the slit is 500 μm or less.

The electron-emitting device according to claim 1,
An electron-emitting device, wherein at least one of the first electrode and the second electrode has an acute angled corner.

The electron-emitting device according to claim 1,
An electron-emitting device, wherein the first electrode and the second electrode include carbon nanotubes.

An electric field applying unit formed of at least one of a piezoelectric material, an electrostrictive material, and an antiferroelectric material,
A first electrode formed on one surface of the electric field application unit;
An electron-emitting device, comprising: a second electrode formed on one surface of the electric field application unit and forming a slit together with the first electrode.

The electron-emitting device according to claim 20,
A third electrode disposed at a predetermined distance from the first and second electrodes;
An electron-emitting device, wherein a space between the first and second electrodes and the third electrode is evacuated.

The electron-emitting device according to claim 21,
An electron-emitting device, wherein the electric field application unit also functions as an actuator, and controls an amount of emitted electrons by a displacement operation thereof.

The electron-emitting device according to claim 21,
A voltage source for applying a DC offset voltage to the third electrode;
An electron-emitting device further comprising a resistor arranged in series between the voltage source and the third electrode.

The electron-emitting device according to claim 20,
An electron-emitting device further comprising a conductive coating provided on the first electrode, the second electrode, and the slit.

The electron-emitting device according to claim 24,
A third electrode disposed at a predetermined distance from the first and second electrodes;
An electron-emitting device, wherein a space between the first and second electrodes and the third electrode is evacuated.

The electron-emitting device according to claim 25,
An electron-emitting device, wherein the electric field application unit also functions as an actuator, and controls an amount of emitted electrons by a displacement operation thereof.

The electron-emitting device according to claim 25,
A voltage source for applying a DC offset voltage to the third electrode;
An electron-emitting device further comprising a resistor arranged in series between the voltage source and the third electrode.

The electron-emitting device according to claim 20,
A first conductive coating portion provided on the first electrode;
An electron-emitting device, further comprising a second conductive coating portion provided on the second electrode in a non-contact state with the first coating portion.

The electron-emitting device according to claim 28,
The electronic device according to claim 1, wherein a high resistance portion having a higher resistance than the first and second conductive coating portions and electrically contacting the first and second conductive coating portions is provided in the slit. Emission element.

The electron-emitting device according to claim 28,
A third electrode disposed at a predetermined distance from the first and second electrodes;
An electron-emitting device, wherein a space between the first and second electrodes and the third electrode is evacuated.

The electron-emitting device according to claim 28,
An electron-emitting device, wherein the electric field application unit also functions as an actuator, and controls an amount of emitted electrons by a displacement operation thereof.

The electron-emitting device according to claim 28,
A voltage source for applying a DC offset voltage to the third electrode;
An electron-emitting device further comprising a resistor arranged in series between the voltage source and the third electrode.

The electron-emitting device according to claim 20,
An electron-emitting device, wherein a pulse voltage is applied to the first electrode and a DC offset voltage is applied to the second electrode.

The electron-emitting device according to claim 20,
An electron-emitting device, further comprising a capacitor arranged in series between the first electrode and a voltage signal source.

The electron-emitting device according to claim 20,
The electron-emitting device according to claim 1, further comprising a fourth electrode formed on the other surface of the electric field applying unit and corresponding to the first electrode.

The electron-emitting device according to claim 35,
An electron-emitting device, wherein a pulse voltage is applied to the fourth electrode and a DC offset voltage is applied to the second electrode.

The electron-emitting device according to claim 20,
An electron-emitting device further comprising a resistor arranged in series between the second electrode and a DC offset voltage source.

The electron-emitting device according to claim 20,
An electron-emitting device, wherein a relative dielectric constant of the electric field application unit is 1000 or more.

The electron-emitting device according to claim 20,
An electron-emitting device, wherein the width of the slit is 500 μm or less.

The electron-emitting device according to claim 20,
An electron-emitting device, wherein at least one of the first electrode and the second electrode has an acute angled corner.

The electron-emitting device according to claim 20,
An electron-emitting device, wherein the first electrode and the second electrode include carbon nanotubes.

A plurality of two-dimensionally arranged electron-emitting devices;
A plurality of phosphors respectively arranged at predetermined intervals for these electron-emitting devices,
Wherein each of the current emitting elements is
An electric field application unit formed of a dielectric,
A first electrode formed on one surface of the electric field application unit;
A second electrode formed on one surface of the electric field applying unit and forming a slit with the first electrode.

43. The field emission display of claim 42,
A third electrode is arranged on a surface of the phosphor opposite to a surface facing the first and second electrodes, respectively.
A field emission display, wherein a space between the first and second electrodes and the phosphor is evacuated.

43. The field emission display of claim 42,
Each of the electron-emitting devices is
A voltage source for applying a DC offset voltage to the third electrode;
A field emission display further comprising a resistor arranged in series between the voltage source and the third electrode.

43. The field emission display of claim 42,
The field emission display according to claim 1, wherein each of the electron emission devices further includes a conductive coating portion provided on the first electrode, the second electrode, and the slit.

The field emission display of claim 45,
A third electrode is arranged on a surface of the phosphor opposite to a surface facing the first and second electrodes, respectively.
A field emission display, wherein a space between the first and second electrodes and the phosphor is evacuated.

The field emission display of claim 45,
Each of the electron-emitting devices is
A voltage source for applying a DC offset voltage to the third electrode;
A field emission display further comprising a resistor arranged in series between the voltage source and the third electrode.

43. The field emission display of claim 42,
Each of the electron-emitting devices is
A first conductive coating portion provided on the first electrode;
The field emission display further comprising a second conductive coating provided on the second electrode in a non-contact state with the first coating.

49. The field emission display of claim 48,
For each of the electron-emitting devices,
A high resistance portion having a higher resistance than the first and second conductive coating portions and electrically contacting the first and second conductive coating portions is provided in the slit. Emission display.

49. The field emission display of claim 48,
A third electrode is arranged on a surface of the phosphor opposite to a surface facing the first and second electrodes, respectively.
A field emission display, wherein a space between the first and second electrodes and the phosphor is evacuated.

49. The field emission display of claim 48,
Each of the electron-emitting devices is
A voltage source for applying a DC offset voltage to the third electrode;
A field emission display further comprising a resistor arranged in series between the voltage source and the third electrode.

43. The field emission display of claim 42,
A pulsed voltage is applied to the first electrode, and a DC offset voltage is applied to the second electrode.

43. The field emission display of claim 42,
Wherein each of the current emitting elements is
The field emission display further comprising a capacitor arranged in series between the first electrode and a voltage signal source.

43. The field emission display of claim 42,
Wherein each of the current emitting elements is
A field emission display further comprising a fourth electrode formed on the other surface of the electric field application unit and corresponding to the first electrode.

55. The field emission display of claim 54,
A field emission display, wherein a pulse voltage is applied to the fourth electrode and a DC offset voltage is applied to the second electrode.

43. The field emission display of claim 42,
Wherein each of the current emitting elements is
A field emission display further comprising a resistor arranged in series between the second electrode and a DC offset voltage source.

43. The field emission display of claim 42,
A field emission display, wherein a relative dielectric constant of the electric field application unit is 1000 or more.

43. The field emission display of claim 42,
A field emission display characterized in that the width of the slit is 500 μm or less.

43. The field emission display of claim 42,
A field emission display, wherein at least one of the first electrode and the second electrode has an acute angled corner.

43. The field emission display of claim 42,
A field emission display, wherein the first electrode and the second electrode include carbon nanotubes.

43. The field emission display of claim 42,
A field emission display further comprising a substrate integrally formed with a plurality of two-dimensionally arranged electron-emitting devices.

A plurality of two-dimensionally arranged electron-emitting devices;
A plurality of phosphors respectively arranged at predetermined intervals for these electron-emitting devices,
Wherein each of the current emitting elements is
An electric field applying unit formed of at least one of a piezoelectric material, an electrostrictive material, and an antiferroelectric material,
A first electrode formed on one surface of the electric field application unit;
A second electrode formed on one surface of the electric field applying unit and forming a slit with the first electrode.

The field emission display of claim 62,
A third electrode is arranged on a surface of the phosphor opposite to a surface facing the first and second electrodes, respectively.
A field emission display, wherein a space between the first and second electrodes and the phosphor is evacuated.

The field emission display of claim 62,
A field emission display, wherein the electric field application unit also functions as an actuator, and controls the amount of emitted electrons by its displacement operation.

The field emission display of claim 62,
Each of the electron-emitting devices is
A voltage source for applying a DC offset voltage to the third electrode;
A field emission display further comprising a resistor arranged in series between the voltage source and the third electrode.

The field emission display of claim 62,
The field emission display according to claim 1, wherein each of the electron emission devices further includes a conductive coating portion provided on the first electrode, the second electrode, and the slit.

67. The field emission display of claim 66,
A third electrode is arranged on a surface of the phosphor opposite to a surface facing the first and second electrodes, respectively.
A field emission display, wherein a space between the first and second electrodes and the phosphor is evacuated.

67. The field emission display of claim 66,
A field emission display, wherein the electric field application unit also functions as an actuator, and controls the amount of emitted electrons by its displacement operation.

67. The field emission display of claim 66,
Each of the electron-emitting devices is
A voltage source for applying a DC offset voltage to the third electrode;
A field emission display further comprising a resistor arranged in series between the voltage source and the third electrode.

The field emission display of claim 62,
Each of the electron-emitting devices is
A first conductive coating portion provided on the first electrode;
The field emission display further comprising a second conductive coating provided on the second electrode in a non-contact state with the first coating.

71. The field emission display of claim 70,
For each of the electron-emitting devices,
A high resistance portion having a higher resistance than the first and second conductive coating portions and electrically contacting the first and second conductive coating portions is provided in the slit. Emission display.

71. The field emission display of claim 70,
A third electrode is arranged on a surface of the phosphor opposite to a surface facing the first and second electrodes, respectively.
A field emission display, wherein a space between the first and second electrodes and the phosphor is evacuated.

71. The field emission display of claim 70,
A field emission display, wherein the electric field application unit also functions as an actuator, and controls the amount of emitted electrons by its displacement operation.

71. The field emission display of claim 70,
Each of the electron-emitting devices is
A voltage source for applying a DC offset voltage to the third electrode;
A field emission display further comprising a resistor arranged in series between the voltage source and the third electrode.

The field emission display of claim 62,
A pulsed voltage is applied to the first electrode, and a DC offset voltage is applied to the second electrode.

The field emission display of claim 62,
Wherein each of the current emitting elements is
The field emission display further comprising a capacitor arranged in series between the first electrode and a voltage signal source.

The field emission display of claim 62,
Wherein each of the current emitting elements is
A field emission display further comprising a fourth electrode formed on the other surface of the electric field application unit and corresponding to the first electrode.

The field emission display of claim 77,
A field emission display, wherein a pulse voltage is applied to the fourth electrode and a DC offset voltage is applied to the second electrode.

The field emission display of claim 62,
Wherein each of the current emitting elements is
A field emission display further comprising a resistor arranged in series between the second electrode and a DC offset voltage source.

The field emission display of claim 62,
A field emission display, wherein a relative dielectric constant of the electric field application unit is 1000 or more.

The field emission display of claim 62,
A field emission display characterized in that the width of the slit is 500 μm or less.

The field emission display of claim 62,
A field emission display, wherein at least one of the first electrode and the second electrode has an acute angled corner.

The field emission display of claim 62,
A field emission display, wherein the first electrode and the second electrode include carbon nanotubes.

The field emission display of claim 62,
A field emission display further comprising a substrate integrally formed with a plurality of two-dimensionally arranged electron-emitting devices.