JP3592070B2 - Image forming device - Google Patents

Description

および
【００１５】
【数５】

（但し、上記（数式１）および（数式２）において、Ｗは導電捕獲体の開口部幅であり、Ｗｓは導電捕獲体の非開口部幅である。）
としたときに、
【００１６】
【数６】

におけるＨを満たす２つの解である。〕
本発明では、前記導電捕獲体を所定距離だけフェースプレートから隔てるには、所定の高さの隔壁状部材をフェースプレート上に設けることによって行うことができる。
【００１７】
【発明の実施の形態】
図１（ａ）は、本発明の画像形成装置のフェースプレート部分の１例を示した図である。この例では、青板ガラス等からなるフェースプレート基板１０５のリアプレート側表面上に、蛍光体１０６と蛍光体１０６を仕切り、外光反射低減の目的で設置されるブラックストライプ１２６が形成され、さらにその表面にアルミニウム膜（メタルバック）１１０が形成されて構成されている。この例では、アルミニウム膜で発生する後方散乱電子を抑制するためアルミニウム膜１１０上にグラファイト層１０７等のカーボン層が形成されている。
【００１８】
後方散乱電子を捕獲する導電捕獲体１１３は、フェースプレートから距離Ｈだけ離れた位置に設置され、垂直方向に見たときに蛍光体１０６の一部が見えるような開口幅Ｗの開口を有している。鳥瞰図は、図１（ｂ）のようになっている。導電捕獲体は、電子が衝突したときにその電子を捕獲する働きをするものであり、導電性の材料で形成される。例えば、アルミニウム、ステンレス等の金属等が好適であるが、熱膨張率がフェースプレートに近いほど好ましい。開口部は、これらの材料の薄板にエッチング等の適当な手段により形成することができる。また、捕獲した電子を、外部に逃がすことで電荷の蓄積を防止するために通常特定の電位に固定される。
【００１９】
図１に示したように、導電捕獲体１１３の表面にグラファイト膜１０７等のカーボン膜を形成し、導電捕獲体表面での電子の散乱を抑止することで、さらにハレーションを低減することができる。
【００２０】
ここで、導電捕獲体とフェースプレート間の距離の最適値を求める方法を、図８（ａ）を参照しながら説明する。図８は、図１を模式的に表したものであり、非発光部であるブラックストライプ１２６と発光部である蛍光体１０６（実際はその表面にアルミニウム膜等が設けられている。）からＨの距離を隔てて導電捕獲体１１３の開口部８１４（幅Ｗ）、非開口部８１５（幅Ｗｓ）がある。
【００２１】
開口部８１４の幅Ｗは一次電子線を遮蔽しない幅に設定し、望ましくは、一次電子線を遮蔽しない最小値に設定することが好ましい。開口部８１４（幅Ｗ）と非開口部８１５（幅Ｗｓ）の和、（Ｗ＋Ｗｓ）は表面伝導型電子放出素子の配列ピッチ間隔、および蛍光体１０６のＲＧＢ方向の配列ピッチに等しい。一次電子線が図中の下方から入射すると、Ｃｏｓ則に従って後方散乱電子が生じる（Ｈ．Ｎｉｅｄｒｉｇ：Ｓｃａｎｎｉｎｇ，Ｖｏｌ．１，１７−３４（１９７８））。実際には、図８で示した後方散乱電子は一次電子線照射電流密度に依存して発生する。本発明では、簡単のため一次電子線の照射電流密度の重心と蛍光体１０６の中心が一致しているとし、後方散乱電子はここから生じると考える。なお、一次電子線の照射電流密度の重心と蛍光体１０６の中心が偏心している場合にも本発明と同様の方法によって最適化できる。
【００２２】
後方散乱電子の中で角度δ（＝δ_１−δ_０）内にあるものは、導電捕獲体８１３にトラップされる。全後方散乱電子数を１とすると、この角度δ内にある後方散乱電子数Ｎ（δ）は、Ｗ、Ｗｓ、Ｈの関数として、次式により表される。
【００２３】
【数７】

図８（ｂ）は（数式４）のＮ（δ）とＨの関係を図示したものであり、ｄＮ（δ）／ｄＨ＝０となるＨ、即ち次式で表されるＨｍａｘのときに最大値Ｎｍａｘをとる。
【００２４】
【数８】

【００２５】
【数９】

従って、フェースプレートからＨｍａｘだけ離れた位置に導電捕獲体を設置することにより、後方散乱電子によるハレーションを最も良く低減できる。但し、Ｈｍａｘの距離でなくても、ＮｍａｘからＮｍａｘ−０．１の間の値を与えるＨ_−０．１〜Ｈ_０．１の距離だけ離して設置すれば、十分にハレーションを低減できる。Ｈ_−０．１およびＨ_０．１は、前記（数式４）のＮ（δ）がＮｍａｘ−０．１と等しくなるときのＨを求めることで得ることができる。
【００２６】
本発明の導電捕獲体は、図１（ｂ）に示したような網の目のような形状に限らず、例えば図９中に導電捕獲体９１３として示したように、ストライプ状の形状でも良い。ストライプ状にすると、長手方向に後方散乱電子によるハレーションが生じるが、長手方向にはアライメントフリーとなるメリットがある。
【００２７】
フェースプレートと導電捕獲体との距離を規定する隔壁部材は、図１（ｂ）に示したような平板の形状だけでなく、間隔が規定されるものであれば良く、例えば図９中に隔壁部材９１６として示したような円柱状の形状であってもよい。また、隔壁部材をフェースプレート側でなくリアプレート側に設けてもよい。
【００２８】
また、本発明で用いる電子放出素子は、表面伝導型電子放出素子、熱カソードを用いた熱電子源、電界放出型電子放出素子、金属／絶縁層／金属型（半導体型）電子放出素子等の電子を放出する素子であって、平面型画像形成装置に用いられるものであれば特に制限はされない。
【００２９】
【実施例】
以下、実施例を用いて本発明を更に詳述する。
【００３０】
［実施例１］
図２に示すように、本実施例の画像形成装置は、青板ガラスの絶縁性基板２０１上に、表面伝導型電子放出素子２０２が形成されている。グリッド２０４は電子ビームの通過孔を有する変調電極であり、絶縁層２０３上に設置されている。青板ガラスからなるフェースプレート基板２０５のパネル内側面に、透光性導電膜であるＩＴＯ膜２１１、蛍光体２０６、発光効率向上の目的で設けられているアルミニウム膜２１０が順に形成され、さらにこの上に後方散乱電子を防止するためにグラファイト膜２０７が形成されている。尚、ＩＴＯ膜はアルミニウム膜の導電性が十分な場合は必ずしも必要ではない。
【００３１】
導電捕獲体２１３は、表面伝導型電子放出素子２０２から放出された電子線を透過する開口部２１４と、フェースプレート基板２０５側からの後方散乱電子を捕獲する非開口部２１５を有しており、隔壁部材２１６によって、フェースプレートから所定の距離を保って配設されている。また、この実施例では、導電捕獲体２１３のフェースプレート側にはグラファイト超微粒子膜を形成してある。
【００３２】
本実施例ではＷ＝０．２ｍｍ、Ｗｓ＝０．１ｍｍより（数式１）求めたＨ＝０．２０ｍｍを採用した。
【００３３】
また、フリットガラス２０８により、外枠２０９を挟んでフェースプレート基板２０５と基板２０１が封着され、真空外囲器が構成される。表面伝導型電子放出素子２０２は外部駆動回路に接続され、グラファイト膜２０７とアルミニウム膜２１０とＩＴＯ膜２１１は高圧ケーブルによって高圧電源に接続されている。
次に本例の画像形成装置の作製方法について説明する。
【００３４】
まず、表面伝導型電子放出素子２０２の作製方法について図５を参照しながら述べる。絶縁性基板２０１（図５では５０１）を十分に洗浄後、真空蒸着技術、フォトリソグラフィ技術（エッチング、リフトオフ等の加工技術も含む）により基板２０１（図５では５０１）の面上にニッケル等の素子電極５２２、５２３を、例えば素子電極間隔Ｌ＝２μｍ、素子電極長さＷ＝３００μｍ、膜厚ｄ＝１０００Åの大きさで形成した。素子電極５２２、５２３の材料としては導電性を有するものであれば金属、半導体等どのようなものであっても良い。
【００３５】
次に、素子電極５２２と素子電極５２３との間に、有機金属溶液を塗布して放置することにより、有機金属薄膜を形成した。なお、有機金属溶液とは、前記Ｐｄ、Ｒｕ、Ａｇ、Ａｕ、Ｔｉ、Ｉｎ、Ｃｕ、Ｃｒ、Ｆｅ、Ｚｎ、Ｓｎ、Ｔａ、Ｗ、Ｐｂ等の金属を含む有機化合物の溶液である。
【００３６】
この後、有機金属薄膜を加熱処理し、リフトオフ、エッチング等によりパターニングして図５に示すような薄膜５２４を形成した。なお、薄膜５２４の材質は上述した例のみに制限されるものではなく、Ｐｄ、Ｒｕ、Ａｇ、Ａｕ、Ｔｉ、Ｉｎ、Ｃｕ、Ｃｒ、Ｆｅ、Ｚｎ、Ｓｎ、Ｔａ、Ｗ、Ｐｂ等の金属、ＰｄＯ、ＳｎＯ_２、Ｉｎ_２Ｏ_２、ＰｂＯ、Ｓｂ_２Ｏ_３等の酸化物、ＨｆＢ_２、ＺｒＢ_２、ＬａＢ_６、ＣｅＢ_６、ＹＢ_４、ＧｄＢ_４等のホウ化物、ＴｉＣ、ＺｒＣ、ＨｆＣ、ＴａＣ、ＳｉＣ、ＷＣ等の炭化物、ＴｉＮ、ＺｒＮ、ＨｆＮ等の窒化物、Ｓｉ、Ｇｅ等の半導体、カーボン、ＡｇＭｇ、ＮｉＣｕ、Ｐｂ、Ｓｎ等でも良い。さらに、電子放出部を含む薄膜５２４の形成法は、真空蒸着法、スパッタ法、化学的気相堆積法、分散塗布法、ディッピング法、スピナー法等が適用可能で、要するに薄膜が形成できれば特に作製方法は問わない。
【００３７】
次いで、表面伝導型電子放出素子２０２に電力を供給するための配線（不図示）を形成する。まず、Ａｕ、Ｃｕ、Ａｌ等の金属を蒸着、スパッタ等の手段を用い、数μｍ程度の厚さで成膜し、フォトリソグラフィ技術（エッチング、リフトオフ等の加工技術も含む）によって素子電極５２２、５２３に重なるように配線を形成した。この配線の端は外囲器外に出して、外部と電気的接続ができるように形成する。なお、ここで配線の作製方法はこの他、メッキ法、導電性ペーストを用いた印刷法等他の手段も適用でき、作製手段は特に制限されない。
【００３８】
次に、フェースプレート周辺の作製方法について図２および図１を参照して説明する。まず、フェースプレート基板２０５に透光性導電膜であるＩＴＯ膜２１１をスパッタ法にて数百Åの膜厚に成膜した。図２の画像表示面である蛍光体２０６部分は、詳しくは図１のようにブラックストライプ１２６と蛍光体１０６に分かれており、沈降法にて塗布後、焼成を行って形成する。蛍光体２０６上にアクリルエマルジョンを塗布して、いわゆる蛍光面の平滑化処理として知られるフィルミングを行った後、アルミニウム膜２１０を約数千Å程度の厚さに蒸着し、フィルミング成分の有機物を飛散させるために、空気中で焼成を行った。
【００３９】
次に、グラファイト超微粒子を分散させた水溶液をスプレー法にて塗布してグラファイト超微粒子を積層した後焼成して、数千Å程度のグラファイト膜２０７を形成した。グラファイト超微粒子の平均粒径は数百Å程度である。
【００４０】
次に、隔壁部材１１６を絶縁性ガラスペーストをディスペンサーにて所望の膜厚になるまで重ね塗りし、仮焼成した後、さらに焼成し、２００μｍの高さとなるように作製した。
【００４１】
次に、導電捕獲体２１３として、エッチングにて開口部を作製したＹＥＦ４２６合金製（日立金属製、組成：Ｎｉ４２％、Ｃｒ６％、Ｆｅ残り）の金属板上のフェースプレート側に対応する面に、グラファイト超微粒子を分散させた水溶液をスプレー法にて塗布し、焼成し、グラファイト層を形成した。その後、導電捕獲体とフェースプレートを十分に位置合わせを行い、フリット塗布、焼成を行い、封着接合を行った。
【００４２】
次に、表示パネルの作製方法について、図２を参照し説明する。前述の表面伝導型電子放出素子を形成した基板２０１と蛍光体を形成したフェースプレート基板２０５を、外枠２０９（高さ３ｍｍ）を間に挟み、フェースプレート基板２０５、基板２０１と外枠２０９が接する部分にそれぞれにフリットガラス２０８を塗布した。十分に位置合わせを行い、封着温度で所定時間の加熱し（本例の場合は４５０℃、１０分保持）、封着接合した。
【００４３】
次に、排気管（不図示）を通して表示パネル内の圧力をおよそ１０^−６ｔｏｒｒに真空排気する。続いて、フォーミング、すなわち図５中の素子電極５２２、５２３に通電処理を行い、さらに表示パネル全体を加熱して脱ガス、ゲッタフラッシュした後、排気管を封じ切り、表示パネルを作製した。
【００４４】
上述のように作製した表示パネルに外部駆動回路より電気信号を送って駆動し、画像を表示させた。なお、導電捕獲体の電位は電界に撹乱を与えないように、次式で与えられる電位Ｖを与えた。
【００４５】
Ｖ＝Ｖａ（１−Ｈ／Ｄ）
ここに、Ｖａは蛍光体２０６を発光させるために、アルミニウム膜とＩＴＯ膜を通して、印加する電位であり、Ｄはフェースプレートとリアプレート２０１の間隔（ｍｍ）、Ｈはフェースプレートと導電捕獲体の距離（ｍｍ）である。
【００４６】
その結果、図７に示した従来の表示パネルに比較して、後方散乱電子によるハレーション強度が２０％以上低減しており、色純度も増していることが確認された。
【００４７】
その他の比較例として、導電捕獲体とフェースプレートの間隔ＨをＨ＝０．１、０．４、１ｍｍとした場合の画像形成装置も作製した。その結果、導電捕獲体がない場合に比較して、後方散乱電子によるハレーション強度がＨ＝０．１、０．４ｍｍの場合には２０％弱低下しており、Ｈ＝１ｍｍの場合には、数％程度の低下であった。
【００４８】
尚、この実施例では電子放出素子からの電子ビームをグリッドを用いて変調する方式について説明したが、本発明はどのような変調方式であってもよく、交差するＸ方向配線とＹ方向配線により、電子放出素子を選択して画像表示を行うマトリックス配線を用いた方式であっても、同様の結果が得られる。
【００４９】
［実施例２］
図３、図４はそれぞれ実施例２の画像形成装置の斜視断面図、Ａ−Ａ’断面図を示したものである。両図において、同一符号を付してあるものは同一部材を示す。本実施例は、特開平７−２３５２５７号公報に記載されている画像形成装置を同様に、変調機能を有する制御電極であるグリッドを用いて表面伝導型電子放出素子の選択を行い、さらに表面伝導型電子放出素子を有する電子源基板側に遮蔽電極部材を設置し、電子源に飛翔してくる帯電粒子を遮蔽することにより電子源の劣化を防ぐ構成となっている。そして、実施例１と同様に導電捕獲体３１３を設けた構成である。
【００５０】
図３及び図４に示すように、青板ガラスの絶縁性基板３０１上に、表面伝導型電子放出素子３０２が形成されている。遮蔽部材３３２は、電子源に飛翔してくる帯電粒子を遮蔽し、電子源の劣化を防ぐ目的で設置されている。遮蔽部材３３２は導電性を有する薄板（アルミニウム等）であり、配線３４１、３４２上に絶縁層（不図示）を介して設置される。また、遮蔽部材３３２は各電子放出部３０２の直上部を覆い、かつ各電子放出部から放出される電子線の軌道を遮らないように開口３３３が形成されている。具体的には、電子放出部の直上から４０μｍずれた位置に中心をもつ半径３０μｍの電子線が通過する開口３３３を遮蔽部材３３２上に形成した。
【００５１】
遮蔽部材の開口３３３を透過した電子ビームはグリッド３３０にて変調制御され、グリッド３３０の開口３３１、そして導電捕獲体３１３の開口部３１４を通過し、蛍光体３０６を励起、発光させる。グリッド３３０は配線３４１，３４２と直交して設けられたストライプ状の制御電極、３３１は電子放出素子３０２に一対一対応で設けられた電子線が通過する開口である。グリッド３３０は電子放出素子３０２エリア外に設けた支柱（不図示）によって、支持、固定されている。青板ガラスからなるフェースプレート基板３０５の内面側には、透光性導電膜であるＩＴＯ膜３１１、蛍光体３０６、アルミニウム膜３１０が実施例１と同様に形成され、その上に後方散乱電子を防止するためにグラファイト超微粒子膜３０７が形成されている。
【００５２】
ここで、導電捕獲体３１３は、表面伝導型電子放出素子３０２から放出された電子線を透過する開口部３１４と、非開口部３１５を有している。なお、この導電捕獲体３１３のフェースプレート基板３０５側にはグラファイト超微粒子膜（不図示）を形成してあり、導電捕獲体３１３とフェースプレート基板３０５の間隔を規定するために隔壁部材３１６を設けてある。
【００５３】
フリットガラス３０８により、外枠３０９を挟んでフェースプレート基板３０５と基板３０１が封着され、真空外囲器が構成される。
【００５４】
表面伝導型電子放出素子３０２は素子電極３２２、３２３及び配線３４１、３４２を通して，外部駆動回路に接続され、グラファイト微粒子膜３０７とアルミニウム膜３０１、ＩＴＯ膜３１１は高圧ケーブル３１２によって高圧電源３１７に接続されている。尚、導電捕獲体の電位は実施例１と同様に電界に攪乱を与えないように設定されている。
【００５５】
上述のように作製した表示パネルに外部駆動回路より電気信号を送って駆動し、画像を表示させた。
【００５６】
その結果、図７に示した従来の表示パネルに比較して、実施例１と同様にハレーション強度が低下し、色純度も増していることが確認された。
【００５７】
【発明の効果】
本発明によれば、後方散乱電子の蛍光体への再突入を防止し、ハレーションを減少させることにより、高輝度と高コントラストを同時に達成し、色純度の優れた高精細の平板型画像表示装置を提供することができる。
【図面の簡単な説明】
【図１】本発明に係る画像形成装置のフェースプレート付近を示す断面図である。
【図２】実施例１に示した画像形成装置の断面図である。
【図３】実施例２に示した画像形成装置の斜視断面図である。
【図４】図３のＡ−Ａ断面図である。
【図５】本発明の画像形成装置に適用可能な電子放出素子の一例を示す模式図である。
【図６】従来の画像形成装置におけるハレーションを説明する模式図である。
【図７】従来の画像形成装置の一例を示す断面図である。
【図８】導電捕獲体の配置位置関係を説明するための図である。
【図９】本発明に係る画像形成装置の導電捕獲体と隔壁部材の１例を示す図である。
【符号の説明】
１０１，２０１，３０１，５０１，７０１ 絶縁性基板
１０２，２０２，３０２，７０２ 表面伝導型電子放出素子
１０３，２０３，７０３ 絶縁層
１０４，２０４，７０４ グリッド電極
１０５，２０５，３０５，７０５ フェースプレート基板
１０６，２０６，３０６，７０６ 蛍光体
１０７，２０７，３０７ グラファイト超微粒子膜
１１０，２１０，３１０，７１０ アルミニウム膜（メタルバック）
１１３ 導電捕獲体
１１６，２１６，３１６ 隔壁部材
１２６ ブラックストライプ
２０８，３０８，７０８ フリットガラス
２０９，３０９，７０９ 外枠
２１１，３１１ ＩＴＯ膜
３１２，７１２ 高圧ケーブル
２１３，３１３ 導電捕獲体
２１４，３１４ 非開口部
２１５，３１５ 開口部
３１７，７１７ 高圧電源
３２２，３２３，５２２，５２３ 素子電極
３３０ グリッド電極
３３１ 開口部
３３２ 遮蔽部材
３３３ 開口部
３４１，３４２ 配線
５２４ 薄膜
５２５ 電子放出部
８１４ 開口部
８１５ 非開口部
９１３ 導電捕獲体
９１６ 隔壁部材[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a flat type image forming apparatus using an electron source.
[0002]
[Prior art]
2. Description of the Related Art In recent years, a light and thin so-called flat display has attracted attention as an image display device replacing a large and heavy cathode ray tube. As a flat display, a liquid crystal display (Liquid Crystal Display) has been actively researched and developed. However, the liquid crystal display still has problems such as a dark image and a narrow viewing angle.
[0003]
On the other hand, a self-luminous flat display that displays an image by irradiating a phosphor with an electron beam emitted from an electron source to generate fluorescent light can obtain a brighter image and a wider viewing angle than a liquid crystal display device. Since it can respond to demands for larger screens and higher definition, expectations are growing as an alternative to liquid crystal display devices.
[0004]
For example, Japanese Patent Application Laid-Open No. Hei 3-261024 discloses a thin type having a structure in which an electron-emitting device for generating an electron beam is arranged in a vacuum panel sandwiched between a face plate and a rear plate. An image display device is described. A surface conduction electron-emitting device is used as the electron-emitting device, and an electron beam is accelerated to irradiate a phosphor to cause the phosphor to emit light, thereby displaying an image.
[0005]
FIG. 7 is a schematic cross-sectional view showing a conventional example of a flat panel image display device using this surface conduction electron-emitting device.
[0006]
As shown in FIG. 7, a surface conduction electron-emitting device 702 is formed on an insulating material substrate 701 such as a blue sheet glass. The grid 704 is a modulation electrode having holes through which an electron beam passes, and is provided on an insulating layer 703 formed on the substrate 701. A phosphor 706 covered with an Al thin metal back 710 is formed on the inner surface of the panel of the face plate substrate 705 made of blue glass.
[0007]
The face plate substrate 705 and the substrate 701 are sealed by the frit glass 708 with the outer frame 709 interposed therebetween, thereby forming a vacuum envelope. The surface conduction electron-emitting device 702 and the grid 704 are connected to an external drive circuit, and the metal back 710 is connected to a high-voltage power supply 717 by a high-voltage cable 712.
[0008]
FIG. 5 is a schematic diagram showing the configuration of the surface conduction electron-emitting device 702 in detail. The device electrodes 522 and 523 are provided at a predetermined interval L, and the thin film 524 connecting the device electrodes 522 and 523 is formed by applying an organic Pd (for example, an organic CCP4230 manufactured by Okuno Pharmaceutical Co., Ltd.) and then performing a heat treatment. You. The electron emission portion 525 that emits electrons is formed by an energization process called forming. Here, the term “forming” means that a voltage is applied between the element electrodes 522 and 523 and the thin film 524 is locally broken, deformed or altered to form an electron emitting portion 525 which is in an electrically high resistance state. That is.
[0009]
Note that a crack generated in a part of the thin film 524 may be used as the electron-emitting portion 525. In this case, electrons are emitted from the vicinity of the crack. In addition, those using a SnO ₂ film as a thin film of a surface conduction electron-emitting device, those using an Au thin film [G. Dittmer: “Thin Solid Films”, 9, 317 (1972)], a thin film of In ₂ O ₃ / SnO ₂ [M. Hartwell and C.I. G. FIG. Fonstad: "IEEE Trans. ED Conf." 519 (1975)], and those using a carbon thin film [Hisashi Araki et al .: Vacuum, Vol. 26, No. 1, p. 22 (1983)] and the like are reported.
[0010]
In the above-described image display device, when the internal pressure is maintained at a vacuum of about 10 ⁻⁶ torr and a driving pulse voltage is applied to the element electrodes 522 and 523 shown in FIG. Will be released. The electron beam passes through the grid 704, is accelerated by a high positive voltage applied to the phosphor 706 and the metal back 710 from a high voltage power supply, and collides with the phosphor 706 to emit fluorescence. The electron beam can be controlled by a voltage applied to the grid 704 by a driving circuit, whereby the light emission state of the phosphor is controlled and a desired image is displayed.
[0011]
The electron source uses a surface conduction electron-emitting device, a thermionic electron source using a thermal cathode, and a field emission electron-emitting device [W. P. Dyke & W. W. Dolan, "Field emission", Advance in Electron Physics, 8, p89 (1956), C.I. A. Spindt, "Physical Properties of Thin-Film Fields Emissions Cathodes with Molybdenium Cones", J. Am. Appl. Phys. , 47, p5248 (1976)], etc., metal / insulating layer / metal type electron-emitting device [C. A. Mead, "The tunnel-emission amplifier", J. Mol. Appl. Phys. , 32, p646 (1961)].
[0012]
[Problems to be solved by the invention]
In such a flat image display device, depending on the voltage value applied to the metal back, as shown in FIG. 6, about 20% of the electron beam applied to the metal back 710 is backscattered, and Re-enters the metal back 710 to which a high voltage is applied. When the backscattered electrons re-enter the phosphor, unnecessary portions emit light, and a phenomenon called halation occurs. This halation greatly hinders high definition / high contrast and high color purity in the flat-type image forming apparatus. The present invention has been made in view of such problems, and prevents high-luminance and high-contrast simultaneously by preventing back-scattered electrons from re-entering the phosphor and reducing halation, thereby achieving color reproduction. It is an object of the present invention to provide a high-definition, high-definition, planar image display device with excellent purity.
[0013]
[Means for Solving the Problems]
The present invention, aluminum and the rear plate having a plurality of electron-emitting devices, to together when placed in the rear plate and the face, which is formed on the rear plate and the surface facing the top of the phosphor and the phosphor A flat plate- type image forming apparatus having a face plate provided with an image forming member including a film and an opening through which an electron beam emitted from the electron-emitting device passes, and an electron beam incident on the image forming member. a conductive capture body having a non-opening portion for capturing backscattered electron beam generated, to a flat image forming apparatus characterized by comprising at a distance H _-0.1 to H _0.1 from the faceplate.
[However, the above H _-0.1 and H _0.1 are
[0014]
(Equation 4)

And [0015]
(Equation 5)

(However, in the above (Formula 1) and (Formula 2), W is the width of the opening of the conductive trap, and Ws is the width of the non-opening of the conductive trap.)
And when
[0016]
(Equation 6)

Are two solutions that satisfy the H in. ]
In the present invention, the conductive capture body can be separated from the face plate by a predetermined distance by providing a partition member having a predetermined height on the face plate.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1A is a diagram illustrating an example of a face plate portion of the image forming apparatus of the present invention. In this example, on a rear plate side surface of a face plate substrate 105 made of blue plate glass or the like, a phosphor 106 and a phosphor 106 are partitioned, and a black stripe 126 provided for the purpose of reducing external light reflection is formed. An aluminum film (metal back) 110 is formed on the surface. In this example, a carbon layer such as a graphite layer 107 is formed on the aluminum film 110 to suppress backscattered electrons generated in the aluminum film.
[0018]
The conductive capturing body 113 that captures backscattered electrons is provided at a position away from the face plate by a distance H, and has an opening having an opening width W such that a part of the phosphor 106 can be seen when viewed in the vertical direction. ing. The bird's-eye view is as shown in FIG. The conductive capturing body functions to capture the electrons when the electrons collide, and is formed of a conductive material. For example, metals such as aluminum and stainless steel are suitable, but the thermal expansion coefficient is preferably as close to the face plate as possible. The opening can be formed in a thin plate of these materials by appropriate means such as etching. Also, the trapped electrons are usually fixed at a specific potential in order to prevent the accumulation of charges by escaping to the outside.
[0019]
As shown in FIG. 1, halation can be further reduced by forming a carbon film such as a graphite film 107 on the surface of the conductive trap 113 and suppressing scattering of electrons on the surface of the conductive trap.
[0020]
Here, a method for obtaining the optimum value of the distance between the conductive capturing body and the face plate will be described with reference to FIG. FIG. 8 is a schematic view of FIG. 1, in which a black stripe 126 serving as a non-light-emitting portion and a phosphor 106 serving as a light-emitting portion (actually, an aluminum film or the like is provided on the surface of the black portion 126). There is an opening 814 (width W) and a non-opening 815 (width Ws) of the conductive trap 113 at a distance.
[0021]
The width W of the opening 814 is set to a width that does not block the primary electron beam, and is preferably set to a minimum value that does not block the primary electron beam. The sum of the opening 814 (width W) and the non-opening 815 (width Ws), (W + Ws), is equal to the arrangement pitch of the surface conduction electron-emitting devices and the arrangement pitch of the phosphor 106 in the RGB direction. When the primary electron beam enters from below in the figure, backscattered electrons are generated according to the Cos rule (H. Niedrig: Scanning, Vol. 1, 17-34 (1978)). Actually, the backscattered electrons shown in FIG. 8 are generated depending on the primary electron beam irradiation current density. In the present invention, for simplicity, it is assumed that the center of gravity of the irradiation current density of the primary electron beam coincides with the center of the phosphor 106, and that the backscattered electrons are generated from this. Note that, even when the center of gravity of the irradiation current density of the primary electron beam and the center of the phosphor 106 are eccentric, the optimization can be performed by the same method as the present invention.
[0022]
Among the backscattered electrons, those that are within the angle δ (= δ ₁ −δ ₀ ) are trapped by the conductive trap 813. Assuming that the total number of backscattered electrons is 1, the number N (δ) of backscattered electrons within the angle δ is expressed by the following equation as a function of W, Ws, and H.
[0023]
(Equation 7)

FIG. 8B illustrates the relationship between N (δ) and H in (Equation 4). The maximum value is H when dN (δ) / dH = 0, that is, when Hmax represented by the following equation is satisfied. Take the value Nmax.
[0024]
(Equation 8)

[0025]
(Equation 9)

Therefore, halation due to backscattered electrons can be reduced best by arranging the conductive trap at a position Hmax away from the face plate. However, even without the distance Hmax, if placed away by a distance of _H -0.1 _{to H 0.1} which gives a value between Nmax-0.1 from Nmax, it can be sufficiently reduced halation. H _-0.1 and _{H 0.1,} the N of (Equation 4) ([delta]) can be obtained by obtaining H when equal to Nmax-0.1.
[0026]
The conductive capture body of the present invention is not limited to a mesh-like shape as shown in FIG. 1B, and may have a stripe shape, for example, as shown as a conductive capture body 913 in FIG. . When a stripe shape is formed, halation due to backscattered electrons occurs in the longitudinal direction, but there is an advantage that alignment is free in the longitudinal direction.
[0027]
The partition member for defining the distance between the face plate and the conductive capturing body is not limited to the shape of a flat plate as shown in FIG. It may have a columnar shape as shown as the member 916. Further, the partition member may be provided on the rear plate side instead of the face plate side.
[0028]
The electron-emitting device used in the present invention includes a surface conduction electron-emitting device, a thermionic source using a hot cathode, a field-emission electron-emitting device, and a metal / insulating layer / metal-type (semiconductor-type) electron-emitting device. There is no particular limitation on the element that emits electrons as long as it is used in a flat-type image forming apparatus.
[0029]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples.
[0030]
[Example 1]
As shown in FIG. 2, in the image forming apparatus of the present embodiment, a surface conduction electron-emitting device 202 is formed on an insulating substrate 201 made of soda lime glass. The grid 204 is a modulation electrode having an electron beam passage hole, and is provided on the insulating layer 203. On the inner surface of the panel of a face plate substrate 205 made of blue glass, an ITO film 211 as a light-transmitting conductive film, a phosphor 206, and an aluminum film 210 provided for the purpose of improving luminous efficiency are formed in this order. In order to prevent backscattered electrons, a graphite film 207 is formed. Note that the ITO film is not always necessary when the conductivity of the aluminum film is sufficient.
[0031]
The conductive trap 213 has an opening 214 through which the electron beam emitted from the surface conduction electron-emitting device 202 passes, and a non-opening 215 which traps backscattered electrons from the face plate substrate 205 side. The partition member 216 is provided at a predetermined distance from the face plate. In this embodiment, a graphite ultrafine particle film is formed on the face plate side of the conductive trap 213.
[0032]
In this embodiment, H = 0.20 mm obtained from (Formula 1) from W = 0.2 mm and Ws = 0.1 mm was adopted.
[0033]
Further, the face plate substrate 205 and the substrate 201 are sealed by the frit glass 208 with the outer frame 209 interposed therebetween, thereby forming a vacuum envelope. The surface conduction electron-emitting device 202 is connected to an external driving circuit, and the graphite film 207, the aluminum film 210, and the ITO film 211 are connected to a high-voltage power supply by a high-voltage cable.
Next, a method for manufacturing the image forming apparatus of the present example will be described.
[0034]
First, a method for manufacturing the surface conduction electron-emitting device 202 will be described with reference to FIG. After sufficiently cleaning the insulating substrate 201 (501 in FIG. 5), nickel or the like is formed on the surface of the substrate 201 (501 in FIG. 5) by a vacuum deposition technique or a photolithography technique (including processing techniques such as etching and lift-off). The device electrodes 522 and 523 were formed with, for example, a device electrode interval L = 2 μm, a device electrode length W = 300 μm, and a film thickness d = 1000 °. The material of the device electrodes 522 and 523 may be any material such as a metal and a semiconductor as long as it has conductivity.
[0035]
Next, an organometallic solution was applied between the element electrode 522 and the element electrode 523 and allowed to stand to form an organometallic thin film. The organic metal solution is a solution of an organic compound containing a metal such as Pd, Ru, Ag, Au, Ti, In, Cu, Cr, Fe, Zn, Sn, Ta, W, and Pb.
[0036]
Thereafter, the organic metal thin film was subjected to a heat treatment, and was patterned by lift-off, etching or the like to form a thin film 524 as shown in FIG. In addition, the material of the thin film 524 is not limited to the above-described example, but includes metals such as Pd, Ru, Ag, Au, Ti, In, Cu, Cr, Fe, Zn, Sn, Ta, W, and Pb. Oxides such as PdO, SnO ₂ , In ₂ O ₂ , PbO, Sb ₂ O ₃ , borides such as HfB ₂ , ZrB ₂ , LaB ₆ , CeB ₆ , YB ₄ , GdB ₄ , TiC, ZrC, HfC, TaC , SiC, WC, etc., TiN, ZrN, HfN, etc., semiconductors such as Si, Ge, carbon, AgMg, NiCu, Pb, Sn, etc. Further, as a method for forming the thin film 524 including the electron-emitting portion, a vacuum evaporation method, a sputtering method, a chemical vapor deposition method, a dispersion coating method, a dipping method, a spinner method, or the like can be applied. The method does not matter.
[0037]
Next, a wiring (not shown) for supplying power to the surface conduction electron-emitting device 202 is formed. First, a metal such as Au, Cu, or Al is formed into a film having a thickness of about several μm by means of vapor deposition, sputtering, or the like, and the element electrode 522 is formed by a photolithography technique (including processing techniques such as etching and lift-off). The wiring was formed so as to overlap 523. The ends of the wiring are formed so as to extend out of the envelope and to be electrically connected to the outside. Note that, here, other methods such as a plating method and a printing method using a conductive paste can also be applied to the method of manufacturing the wiring, and the manufacturing method is not particularly limited.
[0038]
Next, a manufacturing method around the face plate will be described with reference to FIGS. First, an ITO film 211 which is a light-transmitting conductive film was formed on the face plate substrate 205 to a thickness of several hundreds of square meters by a sputtering method. The phosphor 206 as an image display surface in FIG. 2 is divided into a black stripe 126 and a phosphor 106 as shown in FIG. 1 in detail. After applying an acrylic emulsion on the phosphor 206 and performing filming, which is a so-called smoothing treatment of a phosphor screen, an aluminum film 210 is deposited to a thickness of about several thousand Å, and an organic material of a filming component is formed. Was baked in the air in order to scatter.
[0039]
Next, an aqueous solution in which graphite ultrafine particles were dispersed was applied by a spray method, and the graphite ultrafine particles were laminated and baked to form a graphite film 207 of about several thousand degrees. The average particle size of the graphite ultrafine particles is about several hundreds of square meters.
[0040]
Next, the partition member 116 was overcoated with an insulating glass paste using a dispenser to a desired film thickness, calcined, and then calcined to produce a height of 200 μm.
[0041]
Next, as a conductive capturing body 213, a surface corresponding to the face plate side on a metal plate made of a YEF426 alloy (made by Hitachi Metals, composition: Ni 42%, Cr 6%, Fe remaining) having an opening formed by etching, An aqueous solution in which ultrafine graphite particles were dispersed was applied by a spray method and baked to form a graphite layer. Thereafter, the conductive capture body and the face plate were sufficiently aligned, frit-coated and baked, and sealed and bonded.
[0042]
Next, a method for manufacturing a display panel is described with reference to FIGS. The above-described substrate 201 on which the surface conduction electron-emitting device is formed and the face plate substrate 205 on which the phosphor is formed are sandwiched between the outer frame 209 (height: 3 mm). Frit glass 208 was applied to each of the contacting portions. After sufficient alignment, heating was performed at a sealing temperature for a predetermined time (in the case of this example, 450 ° C., holding for 10 minutes) to perform sealing bonding.
[0043]
Next, the pressure in the display panel is evacuated to about 10 ⁻⁶ torr through an exhaust pipe (not shown). Subsequently, forming, that is, an energizing process was performed on the element electrodes 522 and 523 in FIG. 5, and further, the entire display panel was heated and degassed and getter-flashed, and then the exhaust pipe was sealed off to produce a display panel.
[0044]
The display panel manufactured as described above was driven by sending an electric signal from an external drive circuit to display an image. The potential of the conductive trap was set to a potential V given by the following equation so as not to disturb the electric field.
[0045]
V = Va (1-H / D)
Here, Va is a potential applied through the aluminum film and the ITO film to cause the phosphor 206 to emit light, D is a distance (mm) between the face plate and the rear plate 201, and H is a distance between the face plate and the conductive trap. Distance (mm).
[0046]
As a result, as compared with the conventional display panel shown in FIG. 7, it was confirmed that the halation intensity due to the backscattered electrons was reduced by 20% or more and the color purity was also increased.
[0047]
As another comparative example, an image forming apparatus in which the distance H between the conductive capture body and the face plate was H = 0.1, 0.4, and 1 mm was also manufactured. As a result, the halation intensity due to the backscattered electrons is slightly less than 20% when the backscattered electrons are H = 0.1 and 0.4 mm, and when ha = 1 mm, The decrease was about several percent.
[0048]
In this embodiment, a method of modulating an electron beam from an electron-emitting device using a grid has been described. However, the present invention may employ any modulation method, and the X-direction wiring and the Y-direction wiring cross each other. The same result can be obtained by a method using a matrix wiring for displaying an image by selecting an electron-emitting device.
[0049]
[Example 2]
3 and 4 are a perspective sectional view and an AA 'sectional view of the image forming apparatus of the second embodiment, respectively. In both drawings, the same reference numerals denote the same members. In this embodiment, similarly to the image forming apparatus described in JP-A-7-235257, a surface conduction electron-emitting device is selected by using a grid which is a control electrode having a modulation function, A shielding electrode member is provided on the side of the electron source substrate having the electron-emitting devices, and the charged particles flying to the electron source are shielded to prevent the deterioration of the electron source. Then, similarly to the first embodiment, the conductive trap 313 is provided.
[0050]
As shown in FIGS. 3 and 4, a surface conduction electron-emitting device 302 is formed on an insulating substrate 301 made of blue glass. The shielding member 332 is provided for the purpose of shielding charged particles flying to the electron source and preventing deterioration of the electron source. The shielding member 332 is a conductive thin plate (aluminum or the like) and is provided on the wirings 341 and 342 via an insulating layer (not shown). The shielding member 332 covers an upper portion of each of the electron emitting portions 302, and has an opening 333 so as not to block the trajectory of the electron beam emitted from each of the electron emitting portions. Specifically, an opening 333 through which an electron beam having a radius of 30 μm and having a center at a position shifted by 40 μm from directly above the electron emission portion is formed on the shielding member 332.
[0051]
The modulation of the electron beam transmitted through the opening 333 of the shielding member is performed by the grid 330, and the electron beam passes through the opening 331 of the grid 330 and the opening 314 of the conductive trap 313 to excite and emit the phosphor 306. The grid 330 is a stripe-shaped control electrode provided orthogonal to the wirings 341 and 342, and the reference numeral 331 is an opening provided for the electron-emitting device 302 in one-to-one correspondence, through which an electron beam passes. The grid 330 is supported and fixed by columns (not shown) provided outside the area of the electron-emitting device 302. On the inner surface side of a face plate substrate 305 made of soda lime glass, an ITO film 311 as a light-transmitting conductive film, a phosphor 306, and an aluminum film 310 are formed in the same manner as in Example 1, and backscattered electrons are prevented thereon. For this purpose, a graphite ultrafine particle film 307 is formed.
[0052]
Here, the conductive trap 313 has an opening 314 through which an electron beam emitted from the surface conduction electron-emitting device 302 passes, and a non-opening 315. An ultrafine graphite film (not shown) is formed on the face of the conductive trap 313 on the face plate substrate 305 side, and a partition member 316 is provided to regulate the distance between the conductive trap 313 and the face plate substrate 305. It is.
[0053]
The face plate substrate 305 and the substrate 301 are sealed by the frit glass 308 with the outer frame 309 interposed therebetween, thereby forming a vacuum envelope.
[0054]
The surface conduction electron-emitting device 302 is connected to an external drive circuit through device electrodes 322 and 323 and wirings 341 and 342, and the graphite fine particle film 307 and the aluminum film 301 and the ITO film 311 are connected to a high-voltage power supply 317 by a high-voltage cable 312. ing. Note that the potential of the conductive trap is set so as not to disturb the electric field as in the first embodiment.
[0055]
The display panel manufactured as described above was driven by sending an electric signal from an external drive circuit to display an image.
[0056]
As a result, as compared with the conventional display panel shown in FIG. 7, it was confirmed that the halation intensity was reduced and the color purity was increased as in the case of Example 1.
[0057]
【The invention's effect】
According to the present invention, by preventing backscattered electrons from re-entering the phosphor and reducing halation, high brightness and high contrast are simultaneously achieved, and a high-definition flat type image display device with excellent color purity is achieved. Can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing the vicinity of a face plate of an image forming apparatus according to the present invention.
FIG. 2 is a cross-sectional view of the image forming apparatus according to the first exemplary embodiment.
FIG. 3 is a perspective sectional view of the image forming apparatus shown in Embodiment 2.
FIG. 4 is a sectional view taken along line AA of FIG. 3;
FIG. 5 is a schematic view showing an example of an electron-emitting device applicable to the image forming apparatus of the present invention.
FIG. 6 is a schematic diagram illustrating halation in a conventional image forming apparatus.
FIG. 7 is a cross-sectional view illustrating an example of a conventional image forming apparatus.
FIG. 8 is a diagram for explaining an arrangement positional relationship of a conductive capturing body.
FIG. 9 is a diagram illustrating an example of a conductive capturing body and a partition member of the image forming apparatus according to the present invention.
[Explanation of symbols]
101, 201, 301, 501, 701 Insulating substrates 102, 202, 302, 702 Surface conduction electron-emitting devices 103, 203, 703 Insulating layers 104, 204, 704 Grid electrodes 105, 205, 305, 705 Face plate substrate 106 , 206, 306, 706 Phosphors 107, 207, 307 Graphite ultrafine particle films 110, 210, 310, 710 Aluminum film (metal back)
113 Conductive traps 116, 216, 316 Partition member 126 Black stripes 208, 308, 708 Frit glass 209, 309, 709 Outer frames 211, 311 ITO films 312, 712 High voltage cables 213, 313 Conductive traps 214, 314 Non-opening 215, 315 Opening 317, 717 High-voltage power supply 322, 323, 522, 523 Element electrode 330 Grid electrode 331 Opening 332 Shielding member 333 Opening 341, 342 Wiring 524 Thin film 525 Electron emitting section 814 Opening 815 Non-opening 913 Conductive Capture body 916 Partition member

Claims (5)

Including a rear plate having a plurality of electron-emitting devices, to together when placed in the rear plate and the face, an aluminum film formed on the rear plate and the surface facing the top of the phosphor and the phosphor A flat image forming apparatus having a face plate with an image forming member ;
An electroconductive trap having an opening through which an electron beam emitted from the electron-emitting device passes, and a non-opening for capturing a backscattered electron beam generated when the electron beam enters the image forming member, flat image forming apparatus characterized by comprising at a distance H _-0.1 to H _0.1 from the faceplate.
[However, the above H _-0.1 and H _0.1 are

and

(However, in the above (Formula 1) and (Formula 2), W is the width of the opening of the conductive trap, and Ws is the width of the non-opening of the conductive trap.)
And when

Are two solutions that satisfy the H in. ] The flat-type image forming apparatus according to claim 1, wherein the conductive capturing body is separated from the face plate by a partition member provided on the face plate. The flat image forming apparatus according to claim 1, wherein a carbon layer is provided on the aluminum film. The flat image forming apparatus according to claim 1, wherein a carbon layer is provided on the conductive capturing body. 5. The flat image forming apparatus according to claim 1, wherein said electron-emitting device is a surface conduction electron-emitting device.

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