JP2004146142A - Electron source substrate manufacturing device, solution for it, electron source substrate, and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new manufacturing device for stably manufacturing an electron source substrate having an electron emission element. <P>SOLUTION: A surface conduction type electron emission element group made of a conductive thin film is formed by injecting and imparting, by an ink jet head 33 having a discharge opening diameter Φ below 25 μm, droplets 42 of a solution containing a material for forming the conductive thin film between a plurality of pairs of respective element electrodes 2 and 3 on a substrate 14. The solution (droplet) 43 containing the material for forming the conductive thin film is prepared by dispersing metal fine particles in a liquid, and the metal fine particles are formed of a material softer than a member constituting the discharge opening. <P>COPYRIGHT: (C)2004,JPO

Description

【００４４】
これらのサンプル溶液および噴射ヘッドを使用して評価した結果を表２〜表５に示す。表中、キズの○は１００時間噴射後に、目立ったキズが確認できなかったもの、×はノズル形状、あるいは寸法にまでも影響をおよぼすような多数のすりキズが存在したものである。素子形状の○は１００時間噴射後に、素子を作製した際の、ドットパターンが、狙いの位置（一対の電極間）に良好な丸い形状で形成されたものであり、×は位置がやや狙いの場所から外れていたり、形状がいびつであったり、微小滴が周囲に飛散していたりしたものである。素子性能の○×は後述のフォーミング処理等を行った後の電子放出の良（○）否（×）である。
【００４５】
【表２】

【００４６】
【表３】

【００４７】
【表４】

【００４８】
【表５】

【００４９】
以上の結果より、含有金属微粒子の硬度が、吐出口材質より大であるもの（Ｓ３、Ｓ６）の場合、吐出口に傷がつくことがわかる。また、それによって形成された素子形状は悪く、素子性能も悪いことがわかる。よって、本発明のような製造装置によって、このような表面伝導型電子放出素子を形成する場合には、金属微粒子は吐出口を構成する部材よりやわらかい材料を選ぶ必要があることがわかる。
【００５０】
なお、そのキズに関しては、吐出口の大きさとの関係で、素子形状が悪くならないものもある。参考ヘッドのように、吐出口径がΦ３６μｍもある（＝面積が約１０００μｍ^２）ような場合には、キズはついても吐出口径が大きいために、噴射性能を劣化に至らしめるほどのキズではなく、十分に使用可能な素子形状が得られている。一方、吐出口径がΦ２５μｍ以下（＝面積が約５００μｍ^２未満）の場合のように、面積比較で参考ヘッドの半分以下のような場合には、同じようにキズがついても、吐出口径との比較において与える影響は大であり、良好な素子形状、素子性能が得られないことがわかる。
【００５１】
つまり、それほど微細な表面伝導型電子放出素子を形成しないのであれば、キズの問題は素子性能に影響を与えないので気にすることはないが、本発明のように、吐出口径Φ２５μｍ以下の液滴噴射ヘッドにより、１０Åないし２００Åの金属微粒子を含有する溶液を噴射付与し、導電性薄膜による表面伝導型電子放出素子群を形成するような場合には、吐出口部のキズは、素子性能にとって致命的であるので、キズができないような溶液および吐出口部材の組み合わせを選ぶ必要がある。すなわち、金属微粒子は吐出口を構成する部材よりやわらかい材料とする必要がある。
【００５２】
なお、実験では、丸形状のΦ２５μｍノズル（面積が約４９０μｍ^２）、Φ１６μｍノズル（面積が約２００μｍ^２）、Φ１０μｍノズル（面積が約８０μｍ^２）を使用したが、噴射ヘッドのノズルとして他の形状（たとえば矩形等）のものを使用する場合には、その面積比較をすればよく、たとえば、２２μｍ×２２μｍのノズルが、本発明の丸形状のΦ２５μｍノズルと同等である。言い換えるならば、本発明は面積が５００μｍ^２未満のノズルを使用した噴射ヘッドで、このような溶液を噴射して表面伝導型電子放出素子群を形成する場合に適用されるものである。
【００５３】
また、実験はサーマルインクジェット（バブルインクジェット）方式の噴射ヘッドを使用したが、本発明の製造装置に使用される噴射ヘッドはこれに限定されることなく、圧電素子を用いたピエゾジェット方式、静電力を利用した方式、あるいは荷電制御方式（連続流方式）等いずれのものでも構わない。特にサーマルインクジェット方式は熱を利用するため、使用する溶液が熱劣化するためある程度制限を受けるが、ピエゾジェット方式等のように機械的変位で液滴を噴射する方式は、そのようなことがないため使用できる溶液の選択肢が広いというメリットがある。
【００５４】
このようにして、良好な形状の表面伝導型電子放出素子群のパターン形成を行った後、本発明では以下に説明するようなフォーミング処理によって、電子放出部５を形成する（図１、図２参照）。
電子放出部５は、導電性薄膜４の一部に形成された高抵抗の亀裂により構成され、導電性薄膜４の膜厚、膜質、材料等、あるいはフォーミング処理条件等に依存したものとなる。電子放出部５の内部には、１００Å以下の粒径の導電性微粒子を含む場合もある。
【００５５】
この導電性薄膜４に施すフォーミング処理方法の一例として、通電処理による方法を説明する。素子電極２、３間に、図示しない電源を用いて通電を行うと、導電性薄膜４の部位に構造の変化した電子放出部５が形成される。すなわち、通電フォーミングによれば導電性薄膜４に局所的に破壊、変形もしくは変質等の構造変化した部位が形成され、この部位が電子放出部５となる。
【００５６】
図７は、本発明に適用する上記のごとくの通電フォーミング処理の電圧波形の例を示す図である。電圧波形は特にパルス波形が好ましく、パルス波高値が一定の電圧パルスを連続的に印加する場合（図７（Ａ））と、パルス波高値を増加させながら、電圧パルスを印加する場合（図７（Ｂ））とがある。まずパルス波高値が一定電圧とした場合（図７（Ａ））について説明する。
【００５７】
図７（Ａ）におけるＴ１およびＴ２はそれぞれ電圧波形のパルス幅とパルス間隔であり、Ｔ１を１μｓ〜１０ｍｓ、Ｔ２を１０μｓ〜１００ｍｓとし、三角波の波高値（通電フォーミング時のピーク電圧）を表面伝導型電子放出素子の形態に応じて適宜選択する。このような条件のもと、例えば、数秒ないし数十分間電圧を印加する。また、パルス波形は三角波に限定されるものではなく、矩形波など所望の波形を用いても良い。
図７（Ｂ）におけるＴ１およびＴ２は、図７（Ａ）に示したものと同様にそれぞれ電圧波形のパルス幅とパルス間隔を示し、三角波の波高値（通電フォーミング時のピーク電圧）は、例えば０．１Ｖステップ程度ずつ増加させることができる。
【００５８】
通電フォーミング処理の終了は、パルス間隔Ｔ２中に、導電性薄膜４を局所的に破壊、変形しない程度の電圧を印加し、電流を測定して検知することができる。例えば０．１Ｖ程度の電圧印加により流れる素子電流を測定し、抵抗値を求めて、１ＭΩ以上の抵抗を示した時に通電フォーミングを終了させる。
【００５９】
通電フォーミングを終了した素子には、活性化工程と呼ぶ処理を施すことが望ましい。活性化処理を施すことにより、素子電流Ｉｆ、放出電流Ｉｅが著しく変化する。活性化工程は、例えば、有機物質のガスを含有する雰囲気下で、通電フォーミングと同様に、パルスの印加を繰り返すことで行うことができる。上記の雰囲気は、例えば、油拡散ポンプやロータリーポンプなどを用いて真空容器内を廃棄した場合に、雰囲気内に残留する有機ガスを利用して形成することができる他、イオンポンプなどにより一旦十分に排気した真空中に適当な有機物質のガスを導入することによっても得られる。このときの好ましい有機物質のガス圧は、前述の応用の形態、真空容器の形状や、有機物質の種類などにより異なるため場合に応じ適宜設定される。
【００６０】
上記の有機物質としては、アルカン、アルケン、アルキンの脂肪族炭化水素類、芳香族炭化水素類、アルコール類、アルデヒド類、ケトン類、アミン類、フェノール、カルボン酸、スルホン酸等の有機酸類等を挙げることができ、具体的には、メタン、エタン、プロパンなどＣｎＨ_２ｎ＋２で表される飽和炭化水素、エチレン、プロピレンなどＣｎＨ_２ｎ等の組成式で表される不飽和炭化水素、ベンゼン、トルエン、メタノール、ホルムアルデヒド、アセトアルデヒド、アセトン、メチルエチルケトン、メチルアミン、エチルアミン、フェノール、蟻酸、酢酸、プロピオン酸等が使用できる。この処理により雰囲気中に存在する有機物質から炭素あるいは炭素化合物が素子上に堆積し、素子電流Ｉｆ、放出電流Ｉｅが著しく変化する。活性化工程の終了判定は、素子電流Ｉｆと放出電流Ｉｅを測定しながら行う。なおパルス幅、パルス間隔、パルス波高値などは適宜設定される。炭素あるいは炭素化合物とは、グラファイト（単結晶、多結晶の両者を指す）、非晶質カーボン（非晶質カーボンおよび非晶質カーボンと前記グラファイトの微結晶の混合物を含むカーボン）であり、その膜厚は５００Å以下にするのが好ましく、より好ましくは３００Å以下である。
【００６１】
上述のようにして作成した電子放出素子は、安定化処理を行うことが好ましい。この処理は真空容器内の有機物質の分圧が、１×１０−８Ｔｏｒｒ以下、望ましくは、１×１０−１０Ｔｏｒｒ以下で行うのが良い。真空容器内の圧力は、１０−６〜１０−７Ｔｏｒｒ以下が好ましく、特に、１×１０−８Ｔｏｒｒ以下が好ましい。真空容器を排気する真空排気装置は、装置から発生するオイルが素子の特性に影響を与えないように、オイルを使用しないものを用いるのが好ましい。具体的には、ソープションポンプ、イオンポンプ等の真空排気装置を挙げることができる。さらに、真空容器内を排気するときには、真空容器全体を過熱して真空容器内壁や電子放出素子に吸着した有機物質分子を排気しやすくするのが好ましい。このときの加熱した状態での真空排気条件は、８０〜２００℃で５時間以上が望ましいが、特に、この条件に限るものではなく、真空容器の大きさや形状、電子放出素子の構成などの諸条件により変化する。
【００６２】
なお、上記有機物質の分圧は、質量分析装置により質量数が１０〜２００の炭素と水素を主成分とする有機分子の分圧を測定し、それらの分圧を積算することにより求められる。安定化工程を経た後、駆動時の雰囲気は、上記安定化処理終了時の雰囲気を維持するのが好ましいが、これに限るものではなく、有機物質が十分除去されていれば、真空度自体は多少低下しても十分安定な特性を維持することができる。このような真空雰囲気を採用することにより、新たな炭素あるいは炭素化合物の堆積を抑制でき、結果として素子電流Ｉｆ、放出電流Ｉｅが安定する。
【００６３】
次に、本発明の画像形成装置について述べる。画像形成装置に用いる電子源基板の電子放出素子の配列については種々のものが採用できる。まず、並列に配置した多数の電子放出素子の個々を両端で接続し、電子放出素子の行を多数個配置し（行方向と呼ぶ）、この配線と直交する方向（列方向と呼ぶ）で電子放出素子の上方に配置した制御電極（グリッドとも呼ぶ）により、電子放出素子からの電子を制御駆動する梯子状配置のものがある。これとは別に、電子放出素子をＸ方向およびＹ方向に行列状に複数個配置し、同じ行に配置された複数の電子放出素子の電極の一方を、Ｘ方向の配線に共通に接続し、同じ列に配置された複数の電子放出素子の電極の他方を、Ｙ方向の配線に共通に接続するものが挙げられる。このようなものは、所謂、単純マトリックス配置である。まず単純マトリックス配置について以下に詳述する。
【００６４】
図８は、電子放出素子を複数個マトリックス状に配置して得られる電子源基板の一例を示す図で、図中、７１は電子源基板、７２はＸ方向配線、７３はＹ方向配線、７４は表面伝導型電子放出素子、７５は結線である。Ｘ方向配線７２は、ＤＸ_１、ＤＸ_２、・・・ＤＸ_ｍのｍ本の配線からなり、Ｙ方向配線７３はＤＹ_１、ＤＹ_２、・・・ＤＹ_ｎのｎ本の配線よりなる。また、多数の表面伝導型素子７４にほぼ均等な電圧が供給されるように、材料、膜厚、配線幅が適宜設定される。これらｍ本のＸ方向配線７２とｎ本のＹ方向配線７３間は図示しない層間絶縁層により電気的に分離されてマトリックス配線を構成する（なお、上記ｍ、ｎは共に正の整数である）。
【００６５】
図示しない層間絶縁層は、Ｘ方向配線７２を形成した電子源基板７１の全面域または一部の所望の領域に形成される。Ｘ方向配線７２とＹ方向配線７３はそれぞれ外部端子として引き出される。更に、表面伝導型放出素子７４の素子電極（図示せず）がｍ本のＸ方向配線７２およびｎ本のＹ方向配線７３と結線７５によって電気的に接続されている。Ｘ方向配線７２とＹ方向配線７３を構成する材料、結線７５を構成する材料、及び一対の素子電極を構成する材料は、その構成元素の一部あるいは全部が同一であっても、また、それぞれ異なっても良い。これらの材料は、例えば、前述の素子電極の材料より適宜選択される。素子電極を構成する材料と配線材料が同一である場合には、素子電極に接続した配線も含めて素子電極ということもできる。
【００６６】
Ｘ方向配線７２は、Ｘ方向に配列する表面伝導型放出素子７４の行を入力信号に応じて走査する走査信号を印加するための走査信号発生手段（図示せず）と電気的に接続されている。一方、Ｙ方向配線７３は、Ｙ方向に配列する表面伝導型放出素子７４の各列を入力信号に応じて変調する変調信号を印加するための変調信号発生手段（図示せず）と電気的に接続されている。更に表面伝導型電子放出素子７４の各素子に印加される駆動電圧は、当該素子に印加される走査信号と変調信号の差電圧として供給されるものである。これにより、単純なマトリックス配線だけで個別の素子を選択して独立に駆動可能になる。
【００６７】
次に、以上のようにして作成した単純マトリックス配置の電子源を用いた画像形成装置について説明する。図９は画像形成装置の表示パネルの基本構成の一例を説明するための図で、図中、７１は電子放出素子７４を基板上に作製した電子源基板、８１は電子源基板７１を固定したリアプレート、８２は支持枠、８６はガラス基板８３の内面に蛍光膜８４とメタルバック８５等が形成されたフェースプレートで、リアプレート８１、支持枠８２及びフェースプレート８６にフリットガラス等を塗布し、大気中あるいは窒素中で４００〜５００度で１０分以上焼成することで封着して外囲器８８を構成する。また、図９において、７４は図１に示す構成に相当する表面伝導型電子放出素子、７２、７３はそれぞれ表面伝導型電子放出素子７４の一対の素子電極と接続されたＸ方向配線およびＹ方向配線である。
【００６８】
外囲器８８は、上述の如くフェースプレート８６、支持枠８２、リアプレート８１で構成したが、リアプレート８１は主に電子源基板７１の強度を補強する目的で設けられるため、電子源基板７１自体で十分な強度を持つ場合は別体のリアプレート８１は不要であり、電子源基板７１に直接支持枠８２を封着し、フェースプレート８６、支持枠８２、及び電子源基板７１にて外囲器８８を構成しても良い。また、さらには、フェースプレート８６、リアプレート８１間に、スペーサとよばれる耐大気圧支持部材を設置することで大気圧に対して十分な強度をもつ外囲器８８を構成することもできる。
いずれにしろ、このようなフェースプレートは、電子源基板と積層、一体化して画像形成装置（画像表示装置）を構成するので、電子源基板とほぼ同じ形状、大きさとされる。
【００６９】
図１０は、図９の画像形成装置に用いられる蛍光膜の構成例を示す模式図で、ブラックストライプタイプの蛍光膜を図１０（Ａ）に、ブラックマトリックスタイプの蛍光膜を図１０（Ｂ）に示すものである。図１０において、８４は蛍光膜、９１は黒色導電材、９２は蛍光体である。
【００７０】
蛍光膜８４は、モノクロームの場合は蛍光体のみからなるが、カラーの蛍光膜の場合は、蛍光体の配列によりブラックストライプあるいはブラックマトリックスなどと呼ばれる黒色導電材９１と蛍光体９２とで構成される。ブラックストライプ、ブラックマトリックスを設ける目的は、カラー表示の場合、必要となる三原色蛍光体の各蛍光体９２間の塗り分け部を黒くすることで混色等を目立たなくすることと、蛍光膜８４における外光反射によるコントラストの低下を抑制することである。ブラックストライプの材料としては、通常良く用いられている黒鉛を主成分とする材料だけでなく、導電性があり、光の透過および反射が少ない材料であればこれに限るものではない。
【００７１】
本発明では、上記のようなマトリックス化された蛍光体９２のストライプの方向、あるいはマトリックスの互いに直交する２方向と、前述の表面伝導型電子放出素子７４の互いに直交する２方向とそれぞれが互いに平行になるようにし、かつ、各電子放出素子７４に蛍光体９２が一致するように位置決めして積層し、画像表示装置を構成している。このような構成の画像表示装置は、互いのマトリックスの方向およびその位置が一致しているため、非常に高画質な画像表示装置を実現できる。
ガラス基板８３に蛍光体を塗布する方法としては、モノクローム、カラーによらず、沈澱法や印刷法が用いられる。また、蛍光膜８４（図１０）の内面側には通常、メタルバック８５が設けられる。メタルバック８５は、蛍光体の発光のうち内面側への光をフェースプレート８６側へ鏡面反射することにより輝度を向上すること、電子ビーム加速電圧を印加するための電極として作用すること、外囲器８８内で発生した負イオンの衝突によるダメージからの蛍光体の保護等の役割を有する。
【００７２】
メタルバック８５は、蛍光膜８４を作製後、蛍光膜８４の内面側表面の平滑化処理（通常、フィルミングと呼ばれる）を行い、その後、Ａｌを真空蒸着等で堆積することで作製できる。また、フェースプレート８６には、更に、蛍光膜８４の導電性を高めるため、蛍光膜８４の外面側に透明電極（図示せず）を設けてもよい。前述の外囲器８８を作成するための封着を行う際、カラーの場合は各色蛍光体９２と表面伝導型電子放出素子７４とを対応させなくてはならず、十分な位置合わせを行う必要がある。この十分な位置合わせを行うために、本発明では、前述のように、表面伝導型電子放出素子７４に対向する位置に蛍光体９２を配置するとともに、表面伝導型電子放出素子７４と蛍光体９２のそれぞれのマトリックスの互いに直交する２方向がそれぞれ互いに平行となるようにしている。このような構成の高精度な画像表示装置を得るためには、蛍光体基板も、本発明の電子源基板と同様な位置決め手法をとることが望ましい。
【００７３】
図９に示した画像形成装置は、具体的には、以下のようにして製造される。外囲器８８は前述の安定化工程と同様に、適宜加熱しながらイオンポンプ、ソープションポンプなどのオイルを使用しない排気装置により不図示の排気管を通じて排気し、１０^−７Ｔｏｒｒ程度の真空度の有機物質の十分少ない雰囲気にした後、封止される。外囲器８８の封止後の真空度を維持するためにゲッター処理を行う場合もある。これは、外囲器８８の封止を行う直前あるいは封止後に抵抗加熱あるいは高周波加熱等の加熱法により、外囲器８８内の所定の位置（図示せず）に配置されたゲッターを加熱し、蒸着膜を形成する処理である。ゲッターは通常Ｂａ等が主成分であり、蒸着膜の吸着作用により、例えば１×１０^−５Ｔｏｒｒないし１×１０^−７Ｔｏｒｒの真空度を維持するものである。
【００７４】
次に、単純マトリックス配置型基板を有する電子源を用いて構成した表示パネルを駆動してＮＴＳＣ方式のテレビ信号に基づきテレビジョン表示を行うための駆動回路の一例を示す概略構成を説明する。図１１は、ＮＴＳＣ方式のテレビ信号に応じて表示を行うための駆動回路のブロック図で、その駆動回路を含む画像形成装置を表すものである。図１１において、１０１は画像の表示パネル、１０２は走査回路、１０３は制御回路、１０４はシフトレジスタ、１０５はラインメモリ、１０６は同期信号分離回路、１０７は変調信号発生器、ＶｘおよびＶａは直流電圧源である。
【００７５】
以下、図１１に示す各部の機能を説明する。表示パネル１０１は端子Ｄｏｘ１ないしＤｏｘｍ、端子Ｄｏｙ１ないしＤｏｙｎ、及び高圧端子Ｈｖを介して外部の電気回路と接続している。このうち、端子Ｄｏｘ１ないしＤｏｘｍには表示パネル１０１内に設けられている電子源、すなわちＭ行Ｎ列の行列状にマトリックス配線された表面伝導型電子放出素子群を一行（Ｎ素子）ずつ順次駆動してゆくための走査信号が印加される。一方、端子Ｄｏｙ１ないしＤｏｙｎには前記の走査信号により選択された一行の表面伝導型電子放出素子の各素子の出力電子ビームを制御するための変調信号が印加される。また、高圧端子Ｈｖには直流電圧源Ｖａより、例えば、１０ｋＶの直流電圧が供給されるが、これは、表面伝導型電子放出素子より出力される電子ビームに蛍光体を励起するのに十分なエネルギーを付与するための加速電圧である。
【００７６】
次に、走査回路１０２について説明する。同回路は内部にＭ個のスイッチング素子を備えるもので（図中、Ｓ１ないしＳｍで模式的に示している）、各スイッチング素子は直流電圧源Ｖｘの出力電圧もしくは０Ｖ（グランドレベル）のいずれか一方を選択し、表示パネル１０１の端子Ｄｏｘ１ないしＤｏｘｍと電気的に接続するものである。Ｓ１ないしＳｍの各スイッチング素子は制御回路１０３が出力する制御信号Ｔｓｃａｎに基づいて動作するものであるが、実際には、例えば、ＦＥＴのようなスイッチング素子を組み合わせることにより構成することが可能である。
【００７７】
なお、前記直流電圧源Ｖｘは、前記表面伝導型電子放出素子の特性（電子放出しきい値電圧）に基づき、走査されていない素子に印加される駆動電圧が電子放出しきい値電圧以下となるような一定電圧を出力するよう設定されている。
【００７８】
制御回路１０３は、外部より入力する画像信号に基づいて適切な表示が行われるように、各部の動作を整合させる働きをもつものである。この後説明する同期信号分離回路１０６より送られる同期信号Ｔｓｙｎｃに基づいて、各部に対してＴｓｃａｎ、Ｔｓｆｔ及びＴｍｒｙの各制御信号を発生する。
【００７９】
同期信号分離回路１０６は、外部から入力されるＮＴＳＣ方式のテレビ信号から同期信号成分と輝度信号成分とを分離するための回路であり、周波数分離（フィルタ）回路を用いれば構成できる。同期信号分離回路１０６により分離された同期信号は、良く知られるように垂直同期信号と水平同期信号よりなるが、ここでは、説明の便宜上Ｔｓｙｎｃ信号として図示した。一方、前記テレビ信号から分離された画像の輝度信号成分を便宜上ＤＡＴＡ信号と表すが、同信号はシフトレジスタ１０４に入力される。
【００８０】
シフトレジスタ１０４は、時系列的にシリアルに入力される前記ＤＡＴＡ信号を画像の１ライン毎にシリアル／パラレル変換するためのものであり、制御回路１０３より送られる制御信号Ｔｓｆｔに基づいて動作する。すなわち制御信号Ｔｓｆｔは、シフトレジスタ１０４のシフトクロックであると言い換えても良い。シリアル／パラレル変換された画像１ライン分（電子放出素子Ｎ素子分の駆動データに相当する）のデータはＩｄ１ないしＩｄｎのＮ個の並列信号としてシフトレジスタ１０４より出力される。
【００８１】
ラインメモリ１０５は、画像１ライン分のデータを必要時間の間だけ記憶するための記憶装置であり、制御回路１０３より送られる制御信号Ｔｍｒｙに従って適宜Ｉｄ１ないしＩｄｎの内容を記憶する。記憶した内容は、Ｉｄ１ないしＩｄｎとして出力され変調信号発生器１０７に入力する。
【００８２】
変調信号発生器１０７は、前記画像データＩｄ１ないしＩｄｎの各々に応じて表面伝導型電子放出素子の各々を適切に駆動変調するための信号源であり、その出力信号は端子Ｄｏｙ１ないしＤｏｙｎを通じて表示パネル１０１内の表面伝導型電子放出素子に印加される。
【００８３】
前述したように、本発明に関わる電子放出素子は、放出電流Ｉｅに対して以下の基本特性を有している。すなわち、前述したように電子放出には明確なしきい値電圧Ｖｔｈがあり、Ｖｔｈ以上の電圧を印加された時のみ電子放出が生じる。また電子放出しきい値以上の電圧に対しては素子への印加電圧の変化に応じて放出電流も変化していく。なお、電子放出素子の材料や構成、製造方法を変えることにより電子放出しきい値電圧Ｖｔｈの値や印加電圧に対する放出電流の変化の度合いが変わる場合もあるが、いずれにしても以下のようなことがいえる。
【００８４】
すなわち、本素子にパルス状の電圧を印加する場合、例えば電子放出しきい値以下の電圧を印加しても電子放出は生じないが、電子放出しきい値以上の電圧を印加する場合には電子ビームが出力される。その際、第一にはパルスの波高値Ｖｍを変化させることにより出力電子ビームの強度を制御することが可能であり、第二には、パルスの幅Ｐｗを変化させることにより出力される電子ビームの電荷の総量を制御することが可能である。
【００８５】
従って、入力信号に応じて電子放出素子を変調する方式としては、電圧変調方式、パルス幅変調方式等があげられ、電圧変調方式を実施するには、変調信号発生器１０７として、一定の長さの電圧パルスを発生するが、入力されるデータに応じて適宜パルスの波高値を変調するような電圧変調方式の回路を用いる。またパルス幅変調方式を実施するには、変調信号発生器１０７としては、一定の波高値の電圧パルスを発生するが、入力されるデータに応じて適宜電圧パルスの幅を変調するようなパルス幅変調方式の回路を用いる。
【００８６】
シフトレジスタ１０４やラインメモリ１０５は、デジタル信号式のものであってもアナログ信号式のものであっても差し支えなく、画像信号のシリアル／パラレル変換や記憶が所定の速度で行われればよい。
デジタル信号式のものを用いる場合には、同期信号分離回路１０６の出力信号ＤＡＴＡをデジタル信号化する必要があるが、これは同期信号分離回路１０６の出力部にＡ／Ｄ変換器を備えれば可能である。また、これと関連してラインメモリ１０５の出力信号がデジタル信号かアナログ信号かにより、変調信号発生器１０７に用いられる回路が若干異なったものとなる。
【００８７】
まず、デジタル信号の場合について述べる。電圧変調方式において、変調信号発生器１０７には、例えば、よく知られるＤ／Ａ変換回路を用い、必要に応じて、増幅回路などを付け加えればよい。また、パルス幅変調方式の場合、変調信号発生器１０７は、例えば、高速の発振器、発振器が出力する波数を計数する計数器（カウンタ）、及び計数器の出力値とラインメモリ１０５の出力値を比較する比較器（コンパレータ）を組み合せた回路を用いることにより構成できる。必要に応じて、比較器の出力するパルス幅変調された変調信号を表面伝導型電子放出素子の駆動電圧にまで電圧増幅するための増幅器を付け加えてもよい。
【００８８】
次に、アナログ信号の場合について述べる。電圧変調方式においては変調信号発生器１０７には、例えば、よく知られるオペアンプなどを用いた増幅回路を用いればよく、必要に応じて、レベルシフト回路などを付け加えてもよい。また、パルス幅変調方式の場合には、例えば、よく知られた電圧制御型発振回路（ＶＣＯ）を用いればよく、必要に応じて、表面伝導型電子放出素子の駆動電圧にまで電圧増幅するための増幅器を付け加えてもよい。
【００８９】
以上のような構成を有する画像表示装置において、表示パネル１０１の各電子放出素子には、容器外端子Ｄｏｘ１ないしＤｏｘｍ、Ｄｏｙ１ないしＤｏｙｎを通じ、電圧を印加することにより、電子放出させるとともに、高圧端子Ｈｖを通じ、メタルバック８５あるいは透明電極（図示せず）に高圧を印加して電子ビームを加速し、蛍光膜８４に衝突させ、励起・発光させることで画像を表示することができる。
【００９０】
以上に述べた構成は、表示等に用いられる好適な画像形成装置を作製する上で必要な概略構成であり、例えば、各部材の材料等、詳細な部分は上述内容に限られるものではなく、画像形成装置の用途に適するよう適宜選択する。また、入力信号例として、ＮＴＳＣ方式をあげたが、これに限るものでなく、ＰＡＬ、ＳＥＣＡＭ方式などの諸方式でもよく、また、これよりも、多数の走査線からなるＴＶ信号（例えば、ＭＵＳＥ方式をはじめとする高品位ＴＶ）方式でもよい。
【００９１】
次に、梯子型配置電子源基板および画像表示装置について説明する。
図１２は、電子放出素子を梯子型に配置した電子源基板の構成例を示す模式図で、図中、１１０は電子源基板、１１１は電子放出素子、１１２は電子放出素子１１１に接続したＤｘ１〜Ｄｘ１０よりなる共通配線である。電子放出素子１１１は、基板１１０上にＸ方向に並列に複数個配置されている（この配列を素子行と呼ぶ）。この素子行が複数個基板上に配置され、電子源基板１１０が構成されている。各素子行の共通配線間に駆動電圧を印加することで、各素子行を独立に駆動させることができる。すなわち、電子ビームを放出させたい素子行には、電子放出しきい値以上の電圧を印加し、電子ビームを放出させない素子行には電子放出しきい値以下の電圧を印加すればよい。また、各素子行間の共通配線Ｄｘ２〜Ｄｘ９、例えばＤｘ２、Ｄｘ３を同一配線とするようにしても良い。
【００９２】
図１３は、図１２に示した梯子型配置電子源基板を備えた画像形成装置におけるパネル構造を説明するための図で、図中、１１０は各素子行間の共通配線を同一配線とした電子源基板、１２０はグリッド電極、１２１は電子が通過するための開口、１２２はＤｏｘ１、Ｄｏｘ２・・・Ｄｏｘｍよりなる容器外端子、１２３はグリッド電極１２０と接続されたＧ１、Ｇ２、・・・Ｇｎからなる容器外端子で、その他、図９または図１１と同様の機能を有する部分には、同一符号を付してある。図１３に示す画像形成装置における前述の単純マトリックス配置の画像形成装置（図９）との違いは、電子源基板１１０とフェースプレート８６の間にグリッド電極１２０を備えていることである。
【００９３】
グリッド電極１２０は、表面伝導型放出素子から放出された電子ビームを変調するためのものであり、梯子型配置の素子行と直交して設けられたストライプ状の電極に電子ビームを通過させるため、各素子に対応して１個ずつ円形の開口１２１が設けられている。なお、グリッドの形状や設置位置は図１２に示したものに限定されるものではない。例えば、開口としてメッシュ状に多数の通過口を設けることもでき、グリッドを表面伝導型放出素子の周囲や近傍に設けることもできる。また、容器外端子１２２及びグリッド容器外端子１２３は、図示しない制御回路と電気的に接続されている。
【００９４】
本画像形成装置では、素子行を１列ずつ順次駆動（走査）していくのと同期してグリッド電極列に画像１ライン分の変調信号を同時に印加する。これにより、各電子ビームの蛍光体への照射を制御し、画像を１ラインずつ表示することができる。これによれば、テレビジョン放送の表示装置、テレビ会議システム、コンピュータ等の表示装置の他、感光性ドラム等で用いて構成された光プリンターとしての画像形成装置としても用いることもできる。
【００９５】
【発明の効果】
基板上の複数対の各素子電極間に導電性薄膜を形成するための材料を含有する溶液の液滴を吐出口径Φ２５μｍ以下の液滴噴射ヘッドにより噴射付与し、導電性薄膜による表面伝導型電子放出素子群を形成する電子源基板製造装置において、前記導電性薄膜を形成するための材料を含有する溶液は、液体に金属微粒子を分散させた溶液であり、該金属微粒子は前記吐出口を構成する部材よりやわらかい材料としたので、噴射ヘッドの吐出口がキズついたり、摩耗したりしてその噴射性能劣化が起こることのない、安定して使用できる新規な電子源基板製造装置とすることができた。
【００９６】
上述のような電子源基板製造装置に使用する溶液において、該溶液に含有される前記導電性薄膜を形成するための材料は、前記吐出口を構成する部材よりやわらかい金属微粒子であるようにしたので、このような新規な電子源基板製造装置の噴射ヘッドの吐出口をキズつけたり、摩耗させたりして、その噴射性能劣化を引き起こすということが皆無となり、電子源基板を安定して製造できるようになった。
【００９７】
上述のような電子源基板製造装置によって製作される電子源基板において、前記導電性薄膜は前記液滴付与後に溶媒成分を揮発させてなる薄膜であるとともに、該薄膜は前記電子源基板製造装置の噴射ヘッドの吐出口を構成する部材よりやわらかい金属微粒子を含有するようにして製作されるので、噴射ヘッドの吐出口をキズつけたり、摩耗させたりして、その噴射性能劣化を引き起こすということが皆無となり、高品位な電子放出素子を有する電子源基板が得られるようになった。
【００９８】
また、高品位な表面伝導型電子放出素子のパターンを有し、電子放出素子特性も優れた電子源基板を使用することにより、高画質な画像表示装置を得られるようになった。
【図面の簡単な説明】
【図１】本発明の一実施形態に係る平面型表面伝導型電子放出素子の構成を示す模式図である。
【図２】図１に示す表面伝導型電子放出素子の製造方法を説明するための模式図である。
【図３】本発明に係る電子源基板の製造装置の一例を示す構成図である。
【図４】本発明を適用し得る液滴付与装置の構成の一例を説明するための図である。
【図５】図４の液滴付与装置の吐出ヘッドユニットの要部概略構成図である。
【図６】本発明に係る表面伝導型電子放出素子の製造装置に使用される噴射ヘッドの１例を示す図である。
【図７】本発明による表面伝導型電子放出素子の製造に採用できる通電フォーミング処理における電圧波形の例を示す図である。
【図８】本発明を適用し得るマトリックス配置型電子源基板の一例を示す模式図である。
【図９】本発明を適用し得るマトリックス配置型電子源基板による画像形成装置の表示パネルの基本構成の一例を説明するための図である。
【図１０】本発明を適用し得る画像形成装置に用いられる蛍光膜の構成例を示す模式図である。
【図１１】画像形成装置にＮＴＳＣ方式のテレビ信号に応じて表示を行うための駆動回路の一例を示すブロック図である。
【図１２】本発明を適用し得る梯子型配置型電子源基板の一例を示す模式図である。
【図１３】本発明を適用し得る梯子型配置型電子源基板による画像形成装置の表示パネル基本構成の一例を説明するための図である。
【図１４】従来の電子放出素子の一例を示す図である。
【符号の説明】
１…基板、２、３…素子電極、４…導電性薄膜、５…電子放出部、１０…電子源基板、１１…吐出ヘッドユニット（噴射ヘッド）、１２…キャリッジ、１３…基板保持台、１４…基板、１５…供給チューブ、１６…信号供給ケーブル、１７…噴射ヘッドコントロールボックス、１８…キャリッジ１２のＸ方向スキャンモータ、１９…キャリッジ１２のＹ方向スキャンモータ、２０…コンピュータ、２１…コントロールボックス、２２（２２Ｘ１、２２Ｙ１、２２Ｘ２、２２Ｙ２）…基板位置決め／保持手段、３０…吐出ヘッドユニット、３１…ヘッドアライメント制御機構、３２…検出光学系、３３…インクジェットヘッド、３４…ヘッドアライメント微動機構、３５…制御コンピュータ、３６…画像識別機構、３７…ＸＹ方向走査機構、３８…位置検出機構、３９…位置補正制御機構、４０…インクジェットヘッド駆動・制御機構、４１…光軸、４２…液滴、４３…液滴着弾位置、５０…噴射ヘッド（インクジェットヘッド）、５１…発熱体基板、５２…蓋基板、５３…発熱体基板５１の作成に用いるシリコン基板、５４…個別電極、５５…共通電極、５６…発熱体、５７…溶液流入口、５８…ノズル、５９…溝部、６０…凹部領域、７１…電子源基板、７２…Ｘ方向配線、７３…Ｙ方向配線、７４…表面伝導型電子放出素子、７５…結線、８１…リアプレート、８２…支持枠、８３…ガラス基板、８４…蛍光膜、８５…メタルバック、８６…フェースプレート、８８…外囲器、９１…黒色導電材、９２…蛍光体、１０１…画像の表示パネル、１０２…走査回路、１０３…制御回路、１０４…シフトレジスタ、１０５…ラインメモリ、１０６…同期信号分離回路、１０７…変調信号発生器、ＶｘおよびＶａ…直流電圧源、１０８…電子放出素子７４に接続したＤｘ１〜Ｄｘ１０よりなる共通配線、１１０…電子源基板、１１１…電子放出素子、１１２…共通配線、１２０…グリッド電極、１２１…開口、１２２…容器外端子、１２３…グリッド容器外端子。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a device for manufacturing an electron source substrate using a surface conduction electron-emitting device, a solution used in the device, an electron source substrate manufactured by the device, and an image display device using the electron source substrate. .
[0002]
[Prior art]
2. Description of the Related Art Conventionally, two types of electron emitting devices, a thermionic electron source and a cold cathode electron source, are known. The cold cathode electron source includes a field emission type (hereinafter, referred to as an FE type), a metal / insulating layer / metal type (hereinafter, referred to as an MIM type), a surface conduction type electron emission element, and the like.
Examples of the FE type include “WP Dyke & WW Dolan,“ Field emission ”, Advance in Electron Physics, 889 (1956)” (Non-Patent Document 1) or “CA Spindt,“ Physical ”. Properties of Thin-Film Field Cathodes with Molybdenium "J. Appl. Phys., 475248 (1976)" (Non-Patent Document 2) and the like are known.
As examples of the MIM type, “CA Mead,“ The Tunnel-emission amplifier ”, J. Appl. Phys., 32 646 (1961)” and the like (Non-Patent Document 3) are known.
[0003]
Examples of the surface conduction electron-emitting device include “MI Elinson, Radio Eng. Electron Phys., 1290 (1965)” (Non-Patent Document 4). The surface conduction electron-emitting device utilizes a phenomenon in which an electron is emitted when a current flows through a small-area thin film formed on a substrate in parallel with the film surface. As the surface conduction electron-emitting device, SnO by Elinson et al. ₂ One using a thin film, one using an Au thin film (for example, “G. Dittmer:“ Thin Solid Films ”, 9317 (1972)) (Non-Patent Document 5)), In ₂ O ₃ / SnO ₂ A thin film (for example, “M. Hartwell and CG Fonstad:“ IEEE Trans. ED Conf. ”, 519 (1975)) (Non-patent Document 6)) and a carbon thin film (for example,“ Hisashi Araki et al .: Vacuum, 26, No. 1, p. 22 (1983) "(Non-Patent Document 7)) and the like.
[0004]
A typical device configuration of these surface conduction electron-emitting devices is described in the aforementioned M.A. The Hartwell device configuration is shown in FIG. In FIG. 14, 1 is a substrate, 2 and 3 are device electrodes, 4 is a conductive thin film, and the conductive thin film 4 is formed of a metal oxide thin film or the like formed by sputtering in an H-shaped pattern. The electron emission portions 5 are formed by an energization process called energization forming. The distance L1 between the device electrodes 2 and 3 in the figure is set at 0.5 to 1 mm, and W1 is set at 0.1 mm.
[0005]
Conventionally, in these surface conduction electron-emitting devices, the electron-emitting portion 5 is generally formed by subjecting the conductive thin film 4 to an energization process called energization forming before performing electron emission. . The energization forming is to apply a DC voltage or a very slowly increasing voltage, for example, about 1 V / min, to both ends of the conductive thin film 4 and to energize the conductive thin film 4 to locally destroy, deform or deteriorate the conductive thin film 4, and to obtain an electrically high voltage. This is to form the electron-emitting portion 5 in a resistance state. In the electron emitting portion 5, a crack is generated in a part of the conductive thin film 4, and electrons are emitted from the vicinity of the crack. In the surface conduction type electron-emitting device subjected to the energization forming process, a voltage is applied to the conductive thin film 4 and a current is caused to flow through the device to cause the electron-emitting portion 5 to emit electrons.
[0006]
The surface conduction electron-emitting device as described above has an advantage that a large number of devices can be arranged and formed over a large area because the structure is simple and the production is easy. Therefore, applied research on charged beam sources, display devices, and the like utilizing this feature has been made. As an example in which a large number of surface conduction electron-emitting devices are arranged and arranged, as will be described later, surface conduction electron-emitting devices are arranged in parallel called a trapezoidal arrangement, and both ends of each element are interconnected (also called a common interconnect). ), An electron source in which a number of connected rows are arranged in many rows (for example, see Patent Documents 1 to 3).
[0007]
In addition, in particular, in image forming apparatuses such as display apparatuses, flat panel display apparatuses using liquid crystal have become widespread in place of CRTs in recent years. However, they are not self-luminous and must have a backlight. Therefore, development of a self-luminous display device has been desired. An example of the self-luminous display device is an image forming device, which is a display device in which an electron source having a large number of surface conduction emission elements arranged therein and a phosphor that emits visible light by electrons emitted from the electron source are combined. (For example, Patent Document 4).
[0008]
However, the method of manufacturing a surface conduction electron-emitting device according to the above-described conventional example uses a lot of photolithography and etching methods in vacuum film formation and a semiconductor process. However, there is a disadvantage that the production cost of the electron source substrate is high.
[0009]
In order to solve the problems described above, the present inventor has disclosed US Pat. No. 3,060,429 (Patent Document 5) and US Pat. No. 3,298,030 in forming a conductive thin film of the element portion of the surface conduction electron-emitting device as described above. No. (Patent Document 6), No. 3596275 (Patent Document 7), No. 3416153 (Patent Document 8), No. 3747120 (Patent Document 9), No. 5729257 (Patent Document) 10) The above-mentioned conductive thin film can be formed stably with good yield and at low cost without using a vacuum film forming method and a photolithography / etching method by an ink jet droplet applying means such as known as 10). I thought it might be. Japanese Unexamined Patent Application Publication No. 2001-319567 (Patent Document 11) discloses the results of various studies on the specific production method.
[0010]
However, unlike ink-jet recording, in which the so-called ink is directed toward paper and recorded, there are many unsolved elements to stably fly a solution containing an element that becomes a conductive thin film and apply it on a substrate. Exists. For example, such an element is generally a metal element, and there are still many unknown techniques for stably spraying a solution containing metal fine particles over a long period of time.
[0011]
[Patent Document 1]
JP-A-64-31332
[Patent Document 2]
JP-A-1-283747
[Patent Document 3]
JP-A-2-257552
[Patent Document 4]
U.S. Pat. No. 5,066,883
[Patent Document 5]
U.S. Pat. No. 3,060,429
[Patent Document 6]
U.S. Pat. No. 3,298,030
[Patent Document 7]
U.S. Pat. No. 3,596,275
[Patent Document 8]
U.S. Pat. No. 3,416,153
[Patent Document 9]
U.S. Pat. No. 3,747,120
[Patent Document 10]
U.S. Pat. No. 5,729,257
[Patent Document 11]
JP 2001-319567 A
[Non-patent document 1]
W. P. Dyke & W. W. Dolan, "Field emission", Advance in Elec
tron Physics, 889 (1956)
[Non-patent document 2]
C. A. Spindt, "Physical Properties of Thin-Film Fieldemis
J. Appl. Phys., 475248 (1976), "ion cathodes with molebdenium".
[Non-Patent Document 3]
C. A. Mead, "The Tunnel-emission amplifier", J. Mol. Appl. Phys.
, 32 646 (1961).
[Non-patent document 4]
M. I. Elinson, Radio Eng. Electron Phys. , 1290 (1965)
[Non-Patent Document 5]
G. FIG. Dittmer: "Thin SolidFilms", 9 317 (1972)
[Non-Patent Document 6]
M. Hartwell and C.I. G. FIG. Fonstad: "IEEE Trans. ED Conf.", 519 (1
975)
[Non-Patent Document 7]
Hisashi Araki et al .: Vacuum, Vol. 26, No. 1, page 22, (1983)
[0012]
[Problems to be solved by the invention]
The present invention relates to an electron source substrate of an image display device using a surface conduction electron-emitting device as described above and an image display device using the same,
A first object is to provide a novel manufacturing apparatus for stably manufacturing an electron source substrate having electron-emitting devices.
A second object is to provide a solution for forming a conductive thin film used in such a manufacturing apparatus.
A third object is to provide an electron source substrate having a high-quality electron-emitting device.
A fourth object is to provide an image display device using an electron source substrate having a high-quality electron-emitting device.
[0013]
[Means for Solving the Problems]
According to a first aspect of the invention, a droplet of a solution containing a material for forming a conductive thin film between a plurality of pairs of element electrodes on a substrate is ejected by a droplet ejecting head having a discharge port diameter of Φ25 μm or less, and the conductive liquid is applied. In the electron source substrate manufacturing apparatus for forming a surface conduction electron-emitting device group using a thin film, the solution containing a material for forming the conductive thin film is a solution in which metal fine particles are dispersed in a liquid, Is characterized by being made of a material softer than the member constituting the discharge port.
[0014]
According to a second aspect of the invention, a droplet of a solution containing a material for forming a conductive thin film between a plurality of pairs of element electrodes on a substrate is ejected by a droplet ejecting head having a discharge port diameter of Φ25 μm or less, and a conductive liquid is applied. In a solution used in an electron source substrate manufacturing apparatus for forming a surface conduction electron-emitting device group using a thin film, a material for forming the conductive thin film contained in the solution is softer than a member constituting the discharge port. It is characterized by being metal fine particles.
[0015]
According to a third aspect of the invention, a droplet of a solution containing a material for forming a conductive thin film between a plurality of pairs of element electrodes on a substrate is ejected by a droplet ejecting head having a discharge port diameter of Φ25 μm or less, and the conductive liquid is applied. In an electron source substrate manufactured by an electron source substrate manufacturing apparatus for forming a surface conduction electron-emitting device group using a thin film, the conductive thin film is a thin film obtained by volatilizing a solvent component after the droplet application, and the thin film Is characterized by containing metal fine particles softer than the member constituting the discharge port.
[0016]
A fourth invention has an electron source substrate according to the third invention, and a face plate which is arranged to face the electron source substrate, has a phosphor mounted thereon, and has substantially the same shape and size as the electron source substrate. It is characterized by the following.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic view showing an example of an electron source substrate constituting a planar surface conduction electron-emitting device according to an embodiment of the present invention. FIG. 1 (A) is a plan view thereof, and FIG. FIG. 2A is a cross-sectional view taken along the line BB of FIG. 1A, wherein 1 is a substrate, 2 and 3 are device electrodes, 4 is a conductive thin film, and 5 is an electron-emitting portion. The basic configuration of the surface conduction electron-emitting device of the present invention is a plane type, and here, for simplification, the configuration of one flat surface conduction electron-emitting device is schematically shown. As described later, such a planar surface conduction electron-emitting device is configured as a device group in which the devices are arranged in a matrix.
[0018]
Examples of the substrate 1 include quartz glass, glass with a reduced content of impurities such as Na, blue plate glass, and SiO 2. ₂ And a ceramic substrate made of alumina or the like, on the surface of which is deposited. As the material of the device electrodes 2 and 3, a general conductive material can be used. For example, metals or alloys such as Ni, Cr, Au, Mo, W, Pt, Ti, Al, Cu, Pd, Pd, As, Ag, Au, RuO ₂ , Pd-Ag or other metal or metal oxide and printed conductor composed of glass, etc., In ₂ O ₃ -SnO ₂ And the like, and a semiconductor material such as polysilicon and the like.
[0019]
The distance L between the device electrodes 2 and 3 is preferably in the range of several thousand to several hundred μm, and more preferably in the range of 1 to 100 μm in consideration of the voltage applied between the device electrodes 2 and 3. is there. The length W of the device electrodes 2 and 3 is several μm to several hundred μm in consideration of the resistance value and the electron emission characteristics of the electrodes, and the film thickness d of the device electrodes 2 and 3 is 100 ° to 1 μm. Range. Incidentally, the present invention is not limited to the configuration shown in FIG. 1, but may be a configuration in which the conductive thin film 4 and the electrodes of the device electrodes 2 and 3 are sequentially formed on the substrate 1.
[0020]
FIG. 2 is a diagram for explaining a method of manufacturing the flat surface conduction electron-emitting device shown in FIG. 1. FIG. 2A is a diagram in which device electrodes 2 and 3 are formed on a substrate 1, and FIG. 2B is a diagram in which a conductive thin film 4 is formed on the device electrodes 2 and 3, and FIG. 2C is a diagram in which an electron emission portion 5 is formed on the conductive thin film 4. The conductive thin film 4 is particularly preferably a fine particle film composed of fine particles in order to obtain good electron emission characteristics. The thickness of the conductive thin film 4 depends on the step coverage of the device electrodes 2 and 3 and the resistance between the device electrodes 2 and 3. It is appropriately set depending on the value and the energizing forming conditions described later, but is preferably several to several thousand degrees, particularly preferably 10 to 500 degrees. In addition, the resistance value of Rs is 10 2 to 10 7 Ω. Note that Rs is a value that appears when the resistance R of a thin film having a thickness t, a width w, and a length of 1 is set as R = Rs (1 / w), and the resistivity of the thin film material is ρ. It is expressed by Rs = ρ / t. Here, the forming process will be described by taking an energizing process as an example, but the forming process is not limited to this, and any method may be used as long as it forms a high resistance state by causing a crack in the film. Is also good.
[0021]
As a material constituting the conductive thin film 4, metals such as Pd, Pt, Ru, Ag, Zn, Sn, W, and Pb can emit good electrons as the surface conduction electron-emitting device of the present invention. As a material. However, as will be described later, it is necessary to consider compatibility with the droplet ejection head used in the manufacturing apparatus of the present invention, and not all of these materials can be used suitably.
[0022]
The fine particle film described here is a film in which a plurality of fine particles are aggregated, and has a fine structure not only in a state in which the fine particles are individually dispersed and arranged, but also in a state in which the fine particles are adjacent to each other or overlap each other (some fine particles are aggregated). (Including the case where an island shape is formed as a whole). The particle size of the fine particles is from several millimeters to 1 micrometer, preferably from 10 millimeters to 200 millimeters.
[0023]
Hereinafter, an apparatus for manufacturing an electron source substrate on which a surface conduction electron-emitting device according to an embodiment of the present invention is formed will be described. FIG. 3 is a view showing an example of an apparatus for manufacturing an electron source substrate according to the present invention. In the figure, 11 is an ejection head unit (ejection head), 12 is a carriage, 13 is a substrate holder, and 14 is a planar surface conduction. A substrate forming a group of electron-emitting devices, 15 is a supply tube for a solution containing a conductive thin film material, 16 is a signal supply cable, 17 is an ejection head control box, 18 is an X-direction scan motor of the carriage 12, and 19 is A Y-direction scan motor of the carriage 12, 20 is a computer, 21 is a control box, and 22 (22X1, 22Y1, 22X2, 22Y2) is a substrate positioning / holding means.
[0024]
The configuration shown in FIG. 3 shows an example in which the ejection head 11 is moved by carriage scanning on the front surface of the substrate 14 placed on the substrate holding table 13 and ejects a solution containing a conductive thin film material. The ejection head 11 may be any mechanism as long as it can discharge a desired amount of liquid droplets, and particularly, an ink jet type mechanism capable of forming droplets of several tens to several picoliters is desirable. As the ink jet method, any of a piezo jet method using a piezoelectric element, a bubble ink jet method in which bubbles are generated using thermal energy of a heater, and a charge control method (continuous flow method) may be used.
[0025]
FIG. 4 is a schematic view for explaining an example of the configuration of a droplet applying apparatus to which the method of manufacturing an electron source substrate according to the present invention can be applied. FIG. FIG. 3 is a schematic configuration diagram of a main part. The configuration of FIG. 4 differs from the configuration of FIG. 3 in that the electron-emitting device group is formed on the substrate by moving the substrate side. 4 and 5, reference numerals 2 and 3 denote element electrodes, 14 denotes a substrate, 30 denotes a discharge head unit (corresponding to the discharge head 11 in FIG. 3), 31 denotes a head alignment control mechanism, 32 denotes a detection optical system, and 33 denotes an ink jet. A head, 34 is a head alignment fine movement mechanism, 35 is a control computer, 36 is an image identification mechanism, 37 is an XY scanning mechanism, 38 is a position detection mechanism, 39 is a position correction control mechanism, 40 is an inkjet head drive / control mechanism, 41 Is an optical axis, 42 is a droplet, and 43 is a droplet landing position.
[0026]
As the droplet applying device (ink jet head 33) of the ejection head unit 30, an ink jet type mechanism is desirable, as in the case of FIG. 3, and a piezo jet type using a piezoelectric element, bubbles using a thermal energy of a heater are used. Or a charge control method (continuous flow method), which generates turbulence, may be used.
[0027]
Hereinafter, the configuration of the apparatus for moving the substrate 14 as described above will be described. First, in FIG. 4, the substrate 14 is placed on the XY scanning mechanism 37. The surface conduction electron-emitting device on the substrate 14 has the same configuration as that of FIG. 1. As a single device, the substrate 1, the device electrodes 2, 3 and the conductive thin film (fine particle film) are similar to those shown in FIG. It consists of four. An ejection head unit 30 for applying liquid droplets is located above the substrate 14. In the present embodiment, the ejection head unit 30 is fixed, and the relative movement between the ejection head unit 30 and the substrate 14 is realized by moving the substrate 14 to an arbitrary position by the XY direction scanning mechanism 37.
[0028]
Next, the configuration of the ejection head unit 30 will be described with reference to FIG. The detection optical system 32 captures image information on the substrate 14, is close to the inkjet head 33 that ejects the droplet 42, and detects the optical axis 41 and the focal position of the detection optical system 32 and the droplet 42 by the inkjet head 33. Are arranged so as to coincide with the landing position 43. In this case, the positional relationship between the detection optical system 32 and the inkjet head 33 can be precisely adjusted by the head alignment fine movement mechanism 34 and the head alignment control mechanism 31. The detection optical system 32 uses a CCD camera and a lens.
[0029]
Returning to FIG. 4, the description will be continued. The image identification mechanism 36 identifies the image information captured by the detection optical system 32, and has a function of binarizing the image contrast and calculating the position of the center of gravity of the binarized specific contrast portion. It is. Specifically, a high-precision image recognition device manufactured by Keyence Corporation; VX-4210 can be used. A means for providing the obtained image information with position information on the substrate 14 is a position detection mechanism 38. For this, a length measuring device such as a linear encoder provided in the XY direction scanning mechanism 37 can be used. A position correction control mechanism 39 performs position correction based on the image information and the position information on the substrate 14, and the movement of the XY direction scanning mechanism 37 is corrected by this mechanism. Further, the inkjet head 33 is driven by the inkjet head drive / control mechanism 40, and the liquid droplets are applied on the substrate 14. The above-described control mechanisms are centrally controlled by the control computer 35.
[0030]
In the above description, the discharge head unit 30 is fixed, and the relative movement between the discharge head unit 30 and the substrate 14 is realized by moving the substrate 14 to an arbitrary position by the XY direction scanning mechanism 37. Needless to say, as shown in FIG. 3, the substrate 14 may be fixed and the ejection head unit 30 may scan in the X and Y directions. In particular, when the present invention is applied to the production of an image forming apparatus having a medium screen of about 200 mm × 200 mm to a large screen of 2000 mm × 2000 mm or more, the substrate 14 is fixed as in the latter case, and the ejection head unit 30 has X, It is preferable that the scanning is performed in two directions of Y, and the application of the liquid droplets is sequentially performed in such two orthogonal directions.
[0031]
When the substrate size is about 200 mm × 200 mm or less, the ejection head unit for applying droplets is of a large array multi-nozzle type capable of covering a range of 200 mm, and the relative movement between the ejection head unit and the substrate is perpendicular to two directions ( Relative movement can be performed only in one direction (for example, only in the X direction) without performing in the X direction and the Y direction, and mass productivity can be improved, but when the substrate size is 200 mm × 200 mm or more. It is difficult to technically and costly to manufacture a large array multi-nozzle type ejection head unit that can cover such a range of 200 mm. , Y so that the liquid droplets of the solution are sequentially applied in such two orthogonal directions. It is better to adopt a configuration in which
[0032]
As a material of the droplet 42, an aqueous solution, an organic solvent, or the like containing the above-described element or compound that becomes a conductive thin film can be used. For example, when the element or compound that forms the conductive thin film is a palladium-based element, a palladium acetate-ethanolamine complex (PA-ME), a palladium acetate-diethanol complex (PA-DE), and a palladium acetate-triethanolamine Aqueous solution containing an ethanolamine-based complex such as a complex (PA-TE), a palladium acetate-butylethanolamine complex (PA-BE), and a palladium acetate-dimethylethanolamine complex (PA-DME); Aqueous solution containing an amine acid complex such as Pd-Gly), a palladium-β-alanine complex (Pd-β-Ala), or a palladium-DL-alanine complex (Pd-DL-Ala); Butyl acetate solution of di-propylamine complex;
[0033]
More specifically, for example, in the case of an aqueous solution of palladium acetate-triethanolamine, it is produced as follows. That is, 50 g of palladium acetate is suspended in 500 cc of isopropyl alcohol, and 100 g of triethanolamine is further added, followed by stirring at 35 ° C. for 12 hours. After completion of the reaction, isopropyl alcohol is removed by evaporation, ethyl alcohol is added to the solid to dissolve and filter, and palladium acetate-triethanolamine is recrystallized from the filtrate. 10 g of the thus obtained palladium acetate-triethanolamine can be dissolved in 190 g of pure water to obtain a solution for injection.
[0034]
As another example, palladium fine particles are ozone-treated with an ozone generator having a voltage of 60 V, a frequency of 50 Hz and an oxygen flow rate of 40 ml / min, and 7 g of the treated palladium fine particles are converted into a solution of 5 g of ethylene glycol, 8 g of ethanol and 80 g of pure water. It can be dispersed to form a solution for jetting.
[0035]
As is clear from the above description, the electron source substrate of the present invention is manufactured by applying a solution containing an element or compound to be a conductive thin film in the air by the principle of ink jet, and applying the solution as a droplet on the substrate. However, in order to stably form a high-quality surface-conduction electron-emitting device over a long period of time, the manufacturing apparatus must maintain stable and constant performance. Here, the most important point is the long-term performance stability of the ejection head. As described above, in the present invention, the solution containing the material for forming the conductive thin film is a solution in which metal fine particles are dispersed in a liquid.
[0036]
However, these metal fine particles exist as abrasive grains dispersed in a solution, and when a large amount of this solution is used, there is a problem that the passage of the solution of the ejection head is damaged or worn. Among the passages, in particular, scratches and abrasion of the discharge port (nozzle) are problematic because they affect the droplet ejection performance of the solution.
[0037]
By the way, since the scratches and the abrasion are generated when two objects collide with each other or rub against each other, it is considered that they can be solved by appropriately selecting the hardness of each object. Although it is true that the flaw also affects the droplet ejection performance of the ejection head, it is considered that the extent of the flaw depends on the size of the flaw and the size of the path of the solution. For example, even if there is a scratch on the order of nanometers in a hose for water discharge having an inner diameter of Φ15 mm to Φ20 mm, it cannot have a great effect on the flow rate of water discharge.
[0038]
In the present invention, in consideration of these points, the hardness of the material of the discharge port, the hardness of the material of the metal fine particles, and the size of the discharge port are intensively studied.
Specifically, by using a jet head as shown in FIG. 5 and using a jet head in which a multi-nozzle plate is attached to the surface of a rectangular nozzle portion 58 (see FIG. 6), a solution is jetted for a certain period of time. Then, it was examined whether or not the discharge port portion (nozzle hole portion) was flawed, and whether or not the deterioration of the solution droplet discharge performance caused the formed element shape (good or bad dot pattern shape) and the deterioration of the device performance. . The multi-nozzle plate was prepared by changing the material and the nozzle diameter (here, a round shape). The device performance was examined after performing a forming process and the like described later.
[0039]
The jet head used was of a thermal ink jet type using thermal energy. As described above, the jet head of FIG. 6 was equipped with a nozzle plate (no nozzle plate is shown). The drawing shows only four discharge ports for the sake of simplicity. The number of ejection ports actually used was 64 and the arrangement density thereof was 400 dpi. In FIG. 6, reference numeral 50 denotes an ejection head, 51 denotes a heating element substrate, 52 denotes a cover substrate, 53 denotes a silicon substrate, 54 denotes an individual electrode, 55 denotes a common electrode, 56 denotes a heating element, 57 denotes a solution inlet, and 58 denotes a solution inlet. FIG. 6A is a perspective view of the ejection head, FIG. 6B is an exploded view in which the heating element substrate 51 and the cover substrate 52 are disassembled, and FIG. Is a perspective view of the lid substrate 52 as viewed from the back side.
[0040]
The size of the heating element was 22 μm × 90 μm, its resistance value was 111Ω, the driving voltage for droplet ejection was 24 V, the driving pulse width was 6.5 μs, and the driving frequency was 12 kHz. Injection was performed continuously for 100 hours, and the ejection port portion after the injection was observed by SEM to check for any scratches.
Discharge diameters of Φ25 μm (H1), Φ16 μm (H2), and Φ10 μm (H3) were prepared. As a comparative reference example, one having a discharge opening diameter of Φ36 μm (reference head) was also prepared. In this case, the number of discharge ports is 48, and the arrangement density is 240 dpi. The size of the heating element was 35 μm × 150 μm, the resistance was 120 Ω, the driving voltage for ink ejection was 30 V, the driving pulse width was 7 μs, and the driving frequency was 3.8 kHz. The thickness of the nozzle plate was 30 μm for H1 and H2, 20 μm for H3, and 40 μm for the reference head. The velocity of the droplet at the time of ejection was about 8 m / s in each of the ejection heads.
[0041]
The nozzle plate was made of Ni and austenitic stainless steel SUS304. For the Ni material, a multi-nozzle plate was manufactured by an electroforming method. For the SUS304 material, a nozzle hole was formed in a stainless steel foil by electric discharge machining. When the hardness was measured by a Vickers hardness meter, the Vickers hardness Hv was 58 to 63 for the Ni material and 170 to 190 for the SUS304 material.
[0042]
The liquids used are S1 to S7 shown in Table 1, and each shows the element name of the contained metal particles and the Vickers hardness Hv in the bulk state. The Vickers hardness Hv is a value from a metal data book (edited by The Japan Institute of Metals, 3rd revised edition, published by Maruzen). The content of the fine particles in each of the solutions was about 7%, and the diameter of the fine particles was 150 ° to 200 °.
[0043]
[Table 1]

[0044]
Tables 2 to 5 show the results of evaluation using these sample solutions and the ejection head. In the table, the mark ○ indicates that no noticeable scratches were observed after 100 hours of injection, and the mark す indicates that there were a large number of scratches affecting the nozzle shape or dimensions. In the element shape, “○” indicates that the dot pattern was formed in a good round shape at the target position (between a pair of electrodes) when the element was manufactured after 100 hours of injection, and “×” indicates that the position was slightly targeted. They are out of place, irregular in shape, or have small droplets scattered around. × of the element performance is good (○) or not (×) of electron emission after performing a forming process or the like described later.
[0045]
[Table 2]

[0046]
[Table 3]

[0047]
[Table 4]

[0048]
[Table 5]

[0049]
From the above results, it is found that when the hardness of the contained metal fine particles is larger than the material of the discharge port (S3, S6), the discharge port is damaged. In addition, it can be seen that the element shape formed thereby is poor and the element performance is also poor. Therefore, when such a surface conduction electron-emitting device is formed by the manufacturing apparatus as in the present invention, it is understood that it is necessary to select a material which is softer than the material constituting the discharge port for the metal fine particles.
[0050]
Some of the flaws do not deteriorate the element shape depending on the size of the discharge port. Like the reference head, the discharge port diameter is as large as Φ36 μm (= the area is about 1000 μm ² In such a case, since the diameter of the discharge port is large even if it is flawed, the flaw is not so large as to deteriorate the jetting performance, and a sufficiently usable element shape is obtained. On the other hand, the discharge port diameter is Φ25 μm or less (= the area is about 500 μm ² In the case of less than half of the reference head in the area comparison as in the case of (1), even if the flaw is similarly formed, the influence on the comparison with the discharge port diameter is large, and a good element shape and element It turns out that performance cannot be obtained.
[0051]
In other words, if a very fine surface conduction electron-emitting device is not formed, the problem of scratches does not affect the device performance, so there is no need to worry. However, as in the present invention, a liquid having a discharge port diameter of Φ25 μm or less is not required. In the case where a solution containing metal particles of 10 ° to 200 ° is sprayed and applied by a droplet spraying head to form a surface conduction type electron-emitting device group by a conductive thin film, the flaw of the discharge port portion is detrimental to the device performance. Since it is fatal, it is necessary to select a combination of a solution and a discharge port member that does not cause scratches. That is, the metal fine particles need to be made of a material softer than the member constituting the discharge port.
[0052]
In the experiment, a circular Φ25 μm nozzle (having an area of about 490 μm ² ), Φ16μm nozzle (area is about 200μm ² ), Φ10μm nozzle (area is about 80μm ² ), But when using a nozzle of another shape (for example, a rectangular shape) as the nozzle of the ejection head, the area of the nozzle may be compared. For example, a 22 μm × 22 μm nozzle may be replaced with the round shape of the present invention. Φ25 μm nozzle. In other words, the present invention has an area of 500 μm ² The present invention is applied to a case where such a solution is ejected by a jet head using nozzles smaller than the nozzles to form a surface conduction electron-emitting device group.
[0053]
In the experiment, a thermal inkjet (bubble inkjet) type ejection head was used, but the ejection head used in the manufacturing apparatus of the present invention is not limited to this, and a piezo jet type using a piezoelectric element, an electrostatic force , Or a charge control method (continuous flow method). In particular, the thermal inkjet method uses heat, so the solution to be used is thermally degraded, so there are some restrictions.However, the method of ejecting droplets by mechanical displacement such as the piezo jet method does not have such a problem. Therefore, there is an advantage that a wide choice of solutions can be used.
[0054]
After the pattern of the surface conduction electron-emitting device group having a good shape is formed in this way, the electron-emitting portion 5 is formed by a forming process described below in the present invention (FIGS. 1 and 2). reference).
The electron-emitting portion 5 is constituted by a high-resistance crack formed in a part of the conductive thin film 4 and depends on the film thickness, film quality, material, etc. of the conductive thin film 4 or the forming condition. In some cases, the inside of the electron emitting portion 5 contains conductive fine particles having a particle size of 100 ° or less.
[0055]
As an example of the forming method applied to the conductive thin film 4, a method using an energization process will be described. When current is applied between the device electrodes 2 and 3 using a power supply (not shown), an electron-emitting portion 5 having a changed structure is formed at the portion of the conductive thin film 4. That is, according to the energization forming, a portion of the conductive thin film 4 where a structural change such as destruction, deformation or alteration is locally formed, and this portion becomes the electron emission portion 5.
[0056]
FIG. 7 is a diagram showing an example of a voltage waveform of the energization forming process as described above applied to the present invention. The voltage waveform is particularly preferably a pulse waveform. A voltage pulse having a constant pulse peak value is continuously applied (FIG. 7A), and a voltage pulse is applied while increasing the pulse peak value (FIG. 7). (B)). First, the case where the pulse crest value is a constant voltage (FIG. 7A) will be described.
[0057]
In FIG. 7A, T1 and T2 are the pulse width and pulse interval of the voltage waveform, respectively, T1 is 1 μs to 10 ms, T2 is 10 μs to 100 ms, and the peak value of the triangular wave (peak voltage at the time of energization forming) is surface conduction. It is appropriately selected according to the form of the electron-emitting device. Under such conditions, for example, a voltage is applied for several seconds to tens of minutes. Further, the pulse waveform is not limited to a triangular wave, and a desired waveform such as a rectangular wave may be used.
T1 and T2 in FIG. 7B indicate the pulse width and pulse interval of the voltage waveform, respectively, as in FIG. 7A, and the peak value of the triangular wave (peak voltage during energization forming) is, for example, It can be increased by about 0.1 V steps.
[0058]
The end of the energization forming process can be detected by applying a voltage that does not locally destroy or deform the conductive thin film 4 during the pulse interval T2, and measuring the current. For example, the element current flowing when a voltage of about 0.1 V is applied is measured, and the resistance value is calculated. When the resistance value indicates 1 MΩ or more, the energization forming is terminated.
[0059]
It is desirable to apply a process called an activation process to the element after the energization forming. By performing the activation process, the element current If and the emission current Ie change significantly. The activation step can be performed, for example, by repeatedly applying a pulse under an atmosphere containing a gas of an organic substance, similarly to the energization forming. The above-mentioned atmosphere can be formed, for example, by using an organic gas remaining in the atmosphere when the inside of the vacuum vessel is discarded using an oil diffusion pump or a rotary pump or the like. It can also be obtained by introducing a gas of an appropriate organic substance into a evacuated vacuum. The preferable gas pressure of the organic substance at this time varies depending on the above-described application form, the shape of the vacuum vessel, the type of the organic substance, and the like, and is appropriately set according to the case.
[0060]
Examples of the organic substance include alkanes, alkenes, alkyne aliphatic hydrocarbons, aromatic hydrocarbons, alcohols, aldehydes, ketones, amines, phenols, carboxylic acids, and organic acids such as sulfonic acids. Specific examples thereof include CnH such as methane, ethane, and propane. ₂ CnH such as saturated hydrocarbon represented by n + 2, ethylene, propylene, etc. ₂ Unsaturated hydrocarbons represented by a composition formula such as n, benzene, toluene, methanol, formaldehyde, acetaldehyde, acetone, methyl ethyl ketone, methylamine, ethylamine, phenol, formic acid, acetic acid, propionic acid and the like can be used. By this treatment, carbon or a carbon compound is deposited on the device from the organic substance existing in the atmosphere, and the device current If and the emission current Ie are significantly changed. The end of the activation step is determined while measuring the element current If and the emission current Ie. Note that the pulse width, pulse interval, pulse crest value, and the like are set as appropriate. The carbon or carbon compound is graphite (refer to both single crystal and polycrystal), amorphous carbon (carbon including amorphous carbon and a mixture of amorphous carbon and the fine crystal of graphite), and The film thickness is preferably not more than 500 °, more preferably not more than 300 °.
[0061]
It is preferable that the electron-emitting device manufactured as described above is subjected to a stabilization process. This treatment is preferably performed at a partial pressure of the organic substance in the vacuum vessel of 1 × 10 −8 Torr or less, preferably 1 × 10 −10 Torr or less. The pressure in the vacuum vessel is preferably 10 −6 to 10 −7 Torr or less, particularly preferably 1 × 10 −8 Torr or less. It is preferable to use a vacuum evacuation device that does not use oil so that the oil generated from the device does not affect the characteristics of the element. Specifically, a vacuum exhaust device such as a sorption pump or an ion pump can be used. Further, when evacuating the inside of the vacuum vessel, it is preferable that the entire vacuum vessel is overheated so that the organic substance molecules adsorbed on the inner wall of the vacuum vessel and the electron-emitting device can be easily evacuated. The vacuum evacuation conditions in the heated state at this time are desirably 5 hours or more at 80 to 200 ° C., but are not particularly limited to these conditions, and various conditions such as the size and shape of the vacuum vessel and the configuration of the electron-emitting device. Varies depending on conditions.
[0062]
The partial pressure of the organic substance is determined by measuring partial pressures of organic molecules having carbon and hydrogen having a mass number of 10 to 200 as a main component by a mass spectrometer, and integrating the partial pressures. After the stabilization step, it is preferable that the atmosphere at the time of driving maintain the atmosphere at the end of the stabilization treatment.However, the present invention is not limited to this.If the organic substance is sufficiently removed, the degree of vacuum itself is reduced. Even if it is slightly reduced, it is possible to maintain sufficiently stable characteristics. By employing such a vacuum atmosphere, deposition of new carbon or a carbon compound can be suppressed, and as a result, the device current If and the emission current Ie are stabilized.
[0063]
Next, the image forming apparatus of the present invention will be described. Various arrangements of the electron-emitting devices on the electron source substrate used in the image forming apparatus can be employed. First, each of a large number of electron-emitting devices arranged in parallel is connected at both ends, a large number of rows of electron-emitting devices are arranged (referred to as a row direction), and electrons are arranged in a direction perpendicular to the wiring (referred to as a column direction). There is a ladder-like arrangement in which electrons from the electron-emitting device are controlled and driven by a control electrode (also called a grid) arranged above the emitting device. Separately, a plurality of electron-emitting devices are arranged in a matrix in the X and Y directions, and one of the electrodes of the plurality of electron-emitting devices arranged in the same row is commonly connected to a wiring in the X direction. One in which the other of the electrodes of the plurality of electron-emitting devices arranged in the same column is commonly connected to a wiring in the Y direction. Such is the so-called simple matrix arrangement. First, the simple matrix arrangement will be described in detail below.
[0064]
FIG. 8 is a view showing an example of an electron source substrate obtained by arranging a plurality of electron-emitting devices in a matrix. In the figure, reference numeral 71 denotes an electron source substrate, 72 denotes an X-direction wiring, 73 denotes a Y-direction wiring, and 74 denotes a Y-direction wiring. Is a surface conduction electron-emitting device, and 75 is a connection. X direction wiring 72 is DX ₁ , DX ₂ , ... DX _m , And the Y direction wiring 73 is DY ₁ , DY ₂ …… DY _n Of n wirings. In addition, the material, the film thickness, and the wiring width are appropriately set so that a substantially uniform voltage is supplied to a large number of surface conduction elements 74. The m X-directional wirings 72 and the n Y-directional wirings 73 are electrically separated by an interlayer insulating layer (not shown) to form a matrix wiring (both m and n are positive integers). .
[0065]
The interlayer insulating layer (not shown) is formed on the entire surface of the electron source substrate 71 on which the X-directional wiring 72 is formed or on a part of a desired region. The X-direction wiring 72 and the Y-direction wiring 73 are respectively drawn as external terminals. Further, the device electrodes (not shown) of the surface conduction electron-emitting device 74 are electrically connected to the m X-direction wires 72 and the n Y-direction wires 73 by connection 75. The material forming the X-direction wiring 72 and the Y-direction wiring 73, the material forming the connection 75, and the material forming the pair of element electrodes may have the same or some of the constituent elements, May be different. These materials are appropriately selected, for example, from the above-described materials for the device electrodes. When the material forming the element electrode is the same as the wiring material, the element electrode can be referred to as the element electrode including the wiring connected to the element electrode.
[0066]
The X-direction wiring 72 is electrically connected to a scanning signal generating means (not shown) for applying a scanning signal for scanning a row of the surface conduction electron-emitting devices 74 arranged in the X direction according to an input signal. I have. On the other hand, the Y-direction wiring 73 is electrically connected to a modulation signal generating means (not shown) for applying a modulation signal for modulating each column of the surface conduction electron-emitting devices 74 arranged in the Y direction according to an input signal. It is connected. Further, the driving voltage applied to each of the surface conduction electron-emitting devices 74 is supplied as a difference voltage between a scanning signal and a modulation signal applied to the device. As a result, individual elements can be selected and driven independently using only a simple matrix wiring.
[0067]
Next, an image forming apparatus using an electron source having a simple matrix arrangement created as described above will be described. FIG. 9 is a view for explaining an example of the basic configuration of the display panel of the image forming apparatus. In the figure, reference numeral 71 denotes an electron source substrate in which an electron-emitting device 74 is formed on a substrate; A rear plate, 82 is a support frame, 86 is a face plate in which a fluorescent film 84 and a metal back 85 are formed on the inner surface of a glass substrate 83, and frit glass or the like is applied to the rear plate 81, the support frame 82, and the face plate 86. The envelope 88 is formed by baking in air or nitrogen at 400 to 500 degrees for 10 minutes or more to seal. 9, reference numeral 74 denotes a surface conduction electron-emitting device corresponding to the configuration shown in FIG. 1, and reference numerals 72 and 73 denote X-direction wiring and Y-direction connected to a pair of device electrodes of the surface conduction electron-emitting device 74, respectively. Wiring.
[0068]
The envelope 88 includes the face plate 86, the support frame 82, and the rear plate 81 as described above. However, since the rear plate 81 is provided mainly for the purpose of reinforcing the strength of the electron source substrate 71, the electron source substrate 71 If it has sufficient strength, the separate rear plate 81 is unnecessary, and the support frame 82 is directly sealed to the electron source substrate 71, and the external plate is externally connected to the face plate 86, the support frame 82, and the electron source substrate 71. The enclosure 88 may be configured. Furthermore, by installing an anti-atmospheric pressure support member called a spacer between the face plate 86 and the rear plate 81, the envelope 88 having sufficient strength against atmospheric pressure can be configured.
In any case, since such a face plate is laminated and integrated with the electron source substrate to form an image forming apparatus (image display device), it has substantially the same shape and size as the electron source substrate.
[0069]
FIG. 10 is a schematic view showing a configuration example of a fluorescent film used in the image forming apparatus of FIG. 9. FIG. 10A shows a black stripe type fluorescent film, and FIG. 10B shows a black matrix type fluorescent film. It is shown in FIG. In FIG. 10, 84 is a fluorescent film, 91 is a black conductive material, and 92 is a phosphor.
[0070]
The fluorescent film 84 is made of only a phosphor in the case of monochrome, but is composed of a black conductive material 91 called a black stripe or a black matrix and a phosphor 92 depending on the arrangement of the phosphor in the case of a color fluorescent film. . The purpose of providing the black stripes and the black matrix is to make the color separation between the phosphors 92 of the necessary three primary color phosphors black in the case of color display so that color mixing and the like become inconspicuous. The purpose is to suppress a decrease in contrast due to light reflection. The material of the black stripe is not limited to the commonly used material containing graphite as a main component, as long as it is conductive and has little light transmission and reflection.
[0071]
In the present invention, the directions of the stripes of the matrixed phosphors 92 as described above, or two directions orthogonal to each other in the matrix, and the two directions orthogonal to each other in the surface conduction electron-emitting device 74 are parallel to each other. And the phosphors 92 are positioned and laminated so as to coincide with the respective electron-emitting devices 74 to constitute an image display device. Since the directions and positions of the matrices of the image display devices having such a configuration match each other, an image display device with extremely high image quality can be realized.
As a method of applying the phosphor on the glass substrate 83, a precipitation method or a printing method is used regardless of monochrome or color. A metal back 85 is usually provided on the inner surface side of the fluorescent film 84 (FIG. 10). The metal back 85 improves the luminance by mirror-reflecting the light emitted from the phosphor toward the inner surface side to the face plate 86 side, acts as an electrode for applying an electron beam acceleration voltage, and It has a role of protecting the phosphor from damage due to collision of negative ions generated in the vessel 88.
[0072]
The metal back 85 can be manufactured by performing a smoothing process (usually called filming) on the inner surface of the fluorescent film 84 after the fluorescent film 84 is manufactured, and then depositing Al by vacuum evaporation or the like. Further, in the face plate 86, a transparent electrode (not shown) may be provided on the outer surface side of the fluorescent film 84 in order to further increase the conductivity of the fluorescent film 84. When performing sealing for forming the above-described envelope 88, in the case of color, the phosphors 92 of each color must correspond to the surface-conduction electron-emitting device 74, and sufficient alignment must be performed. There is. In order to perform this sufficient alignment, according to the present invention, as described above, the phosphor 92 is disposed at a position facing the surface conduction electron-emitting device 74, and the surface conduction electron-emitting device 74 and the phosphor 92 are disposed. The two orthogonal directions of the respective matrices are parallel to each other. In order to obtain a highly accurate image display device having such a configuration, it is desirable that the phosphor substrate also employs the same positioning method as the electron source substrate of the present invention.
[0073]
The image forming apparatus shown in FIG. 9 is specifically manufactured as follows. The envelope 88 is exhausted through an exhaust pipe (not shown) by an exhaust device that does not use oil, such as an ion pump and a sorption pump, while appropriately heating the envelope 88 in the same manner as in the above-described stabilization process. ^-7 After the atmosphere of an organic substance having a degree of vacuum of about Torr is made sufficiently small, sealing is performed. In some cases, a getter process is performed to maintain the degree of vacuum after sealing the envelope 88. This is because the getter disposed at a predetermined position (not shown) in the envelope 88 is heated by a heating method such as resistance heating or high-frequency heating immediately before or after the envelope 88 is sealed. This is a process for forming a deposited film. The getter is usually composed mainly of Ba or the like. ^-5 Torr or 1 × 10 ^-7 It maintains the degree of vacuum of Torr.
[0074]
Next, a schematic configuration showing an example of a drive circuit for driving a display panel formed using an electron source having a simple matrix arrangement type substrate and performing television display based on an NTSC television signal will be described. FIG. 11 is a block diagram of a driving circuit for performing display according to an NTSC television signal, and shows an image forming apparatus including the driving circuit. In FIG. 11, 101 is an image display panel, 102 is a scanning circuit, 103 is a control circuit, 104 is a shift register, 105 is a line memory, 106 is a synchronizing signal separation circuit, 107 is a modulation signal generator, and Vx and Va are DC. It is a voltage source.
[0075]
Hereinafter, the function of each unit shown in FIG. 11 will be described. The display panel 101 is connected to an external electric circuit via terminals Dox1 to Doxm, terminals Doy1 to Doyn, and a high voltage terminal Hv. Of these terminals, the terminals Dox1 to Doxm sequentially drive electron sources provided in the display panel 101, that is, a group of surface conduction electron-emitting devices arranged in a matrix of M rows and N columns, one row at a time (N elements). A scanning signal for performing the scanning is applied. On the other hand, to the terminals Doy1 to Doyn, a modulation signal for controlling the output electron beam of each element of the one row of surface conduction electron-emitting devices selected by the scanning signal is applied. The high-voltage terminal Hv is supplied with a DC voltage of, for example, 10 kV from the DC voltage source Va, which is sufficient to excite the phosphor into an electron beam output from the surface conduction electron-emitting device. It is an accelerating voltage for applying energy.
[0076]
Next, the scanning circuit 102 will be described. The circuit has M switching elements inside (in the figure, S1 to Sm are schematically shown), and each switching element is either an output voltage of a DC voltage source Vx or 0V (ground level). One is selected and electrically connected to the terminals Dox1 to Doxm of the display panel 101. Each of the switching elements S1 to Sm operates based on the control signal Tscan output from the control circuit 103, but can be actually configured by combining switching elements such as FETs, for example. .
[0077]
In the DC voltage source Vx, the drive voltage applied to an unscanned element becomes equal to or lower than the electron emission threshold voltage based on the characteristics (electron emission threshold voltage) of the surface conduction type electron emission element. It is set to output such a constant voltage.
[0078]
The control circuit 103 has a function of matching the operation of each unit so that appropriate display is performed based on an image signal input from the outside. Based on a synchronizing signal Tsync sent from a synchronizing signal separating circuit 106 described later, each control signal of Tscan, Tsft and Tmry is generated for each unit.
[0079]
The synchronization signal separation circuit 106 is a circuit for separating a synchronization signal component and a luminance signal component from an NTSC television signal input from the outside, and can be configured by using a frequency separation (filter) circuit. The synchronization signal separated by the synchronization signal separation circuit 106 is composed of a vertical synchronization signal and a horizontal synchronization signal as is well known, but is illustrated here as a Tsync signal for convenience of explanation. On the other hand, a luminance signal component of an image separated from the television signal is referred to as a DATA signal for convenience, and the signal is input to the shift register 104.
[0080]
The shift register 104 performs serial / parallel conversion of the DATA signal input serially in time series for each line of an image, and operates based on a control signal Tsft sent from the control circuit 103. That is, the control signal Tsft may be rephrased as a shift clock of the shift register 104. The data for one line of the image that has been subjected to the serial / parallel conversion (corresponding to the drive data for the N electron-emitting devices) is output from the shift register 104 as N parallel signals Id1 to Idn.
[0081]
The line memory 105 is a storage device for storing data for one line of an image for a required time only, and stores the contents of Id1 to Idn as appropriate according to a control signal Tmry sent from the control circuit 103. The stored contents are output as Id1 to Idn and input to the modulation signal generator 107.
[0082]
The modulation signal generator 107 is a signal source for appropriately driving and modulating each of the surface conduction electron-emitting devices according to each of the image data Id1 to Idn, and an output signal thereof is supplied to the display panel through terminals Doy1 to Doyn. The voltage is applied to the surface conduction electron-emitting device 101.
[0083]
As described above, the electron-emitting device according to the present invention has the following basic characteristics with respect to the emission current Ie. That is, as described above, electron emission has a clear threshold voltage Vth, and electron emission occurs only when a voltage higher than Vth is applied. For a voltage equal to or higher than the electron emission threshold, the emission current also changes according to the change in the voltage applied to the element. In some cases, the value of the electron emission threshold voltage Vth or the degree of change of the emission current with respect to the applied voltage may be changed by changing the material, configuration, or manufacturing method of the electron emission element. I can say that.
[0084]
In other words, when a pulse-like voltage is applied to the device, for example, when a voltage lower than the electron emission threshold is applied, electron emission does not occur. A beam is output. At this time, first, the intensity of the output electron beam can be controlled by changing the peak value Vm of the pulse, and second, the electron beam output by changing the pulse width Pw can be controlled. Can be controlled.
[0085]
Therefore, as a method of modulating the electron-emitting device in accordance with the input signal, a voltage modulation method, a pulse width modulation method, and the like can be cited. The voltage pulse is generated by using a voltage modulation type circuit that modulates the peak value of the pulse appropriately according to the input data. In order to implement the pulse width modulation method, the modulation signal generator 107 generates a voltage pulse having a constant peak value, but a pulse width that modulates the width of the voltage pulse appropriately according to input data. A modulation type circuit is used.
[0086]
The shift register 104 and the line memory 105 may be of a digital signal type or an analog signal type, as long as the serial / parallel conversion and storage of the image signal are performed at a predetermined speed.
When using a digital signal type, it is necessary to convert the output signal DATA of the synchronization signal separation circuit 106 into a digital signal. This can be achieved by providing an A / D converter at the output of the synchronization signal separation circuit 106. It is possible. In connection with this, the circuit used for the modulation signal generator 107 is slightly different depending on whether the output signal of the line memory 105 is a digital signal or an analog signal.
[0087]
First, the case of a digital signal will be described. In the voltage modulation method, for example, a well-known D / A conversion circuit may be used as the modulation signal generator 107, and an amplification circuit or the like may be added as necessary. In the case of the pulse width modulation method, the modulation signal generator 107 is, for example, a high-speed oscillator, a counter that counts the number of waves output from the oscillator, and outputs the output value of the counter and the output value of the line memory 105. It can be configured by using a circuit in which a comparator for comparison is combined. If necessary, an amplifier for amplifying the voltage of the pulse width modulated signal output from the comparator to the drive voltage of the surface conduction electron-emitting device may be added.
[0088]
Next, the case of an analog signal will be described. In the voltage modulation method, for example, an amplification circuit using a well-known operational amplifier or the like may be used as the modulation signal generator 107, and a level shift circuit or the like may be added as necessary. In the case of the pulse width modulation method, for example, a well-known voltage-controlled oscillation circuit (VCO) may be used, and if necessary, the voltage is amplified to the drive voltage of the surface conduction electron-emitting device. May be added.
[0089]
In the image display device having the above-described configuration, a voltage is applied to each of the electron-emitting devices of the display panel 101 through the external terminals Dox1 to Doxm and Doy1 to Doyn, so that electrons are emitted and the high-voltage terminal Hv , A high voltage is applied to the metal back 85 or a transparent electrode (not shown) to accelerate the electron beam, collide with the fluorescent film 84, and excite and emit light to display an image.
[0090]
The configuration described above is a schematic configuration necessary for manufacturing a suitable image forming apparatus used for display and the like, and, for example, detailed portions such as materials of each member are not limited to the above-described content. It is appropriately selected so as to be suitable for the use of the image forming apparatus. Although the NTSC system has been described as an example of the input signal, the present invention is not limited to this, and various systems such as the PAL and SECAM systems may be used. In addition, a TV signal composed of a larger number of scanning lines (for example, MUSE) And other high-definition TV) systems.
[0091]
Next, the ladder-type arranged electron source substrate and the image display device will be described.
FIG. 12 is a schematic diagram showing a configuration example of an electron source substrate in which the electron-emitting devices are arranged in a ladder shape. In the drawing, 110 is an electron source substrate, 111 is an electron-emitting device, and 112 is Dx1 connected to the electron-emitting device 111. To Dx10. A plurality of electron-emitting devices 111 are arranged on the substrate 110 in parallel in the X direction (this arrangement is called an element row). A plurality of the element rows are arranged on a substrate to form an electron source substrate 110. By applying a drive voltage between the common wires of each element row, each element row can be driven independently. That is, a voltage equal to or higher than the electron emission threshold may be applied to an element row in which an electron beam is to be emitted, and a voltage equal to or lower than the electron emission threshold may be applied to an element row in which an electron beam is not emitted. Further, the common wirings Dx2 to Dx9 between the element rows, for example, Dx2 and Dx3 may be the same wiring.
[0092]
FIG. 13 is a view for explaining a panel structure in an image forming apparatus provided with the ladder-type arrangement electron source substrate shown in FIG. 12, and in the figure, reference numeral 110 denotes an electron source in which the common wiring between each element row is the same wiring. Substrate, 120 is a grid electrode, 121 is an opening through which electrons pass, 122 is an external terminal made of Dox1, Dox2,... Doxm, and 123 is from G1, G2,. The other parts having the same functions as those in FIG. 9 or FIG. 11 are denoted by the same reference numerals. The difference between the image forming apparatus shown in FIG. 13 and the image forming apparatus having the above-described simple matrix arrangement (FIG. 9) is that a grid electrode 120 is provided between the electron source substrate 110 and the face plate 86.
[0093]
The grid electrode 120 is for modulating the electron beam emitted from the surface conduction electron-emitting device, and allows the electron beam to pass through a stripe-shaped electrode provided orthogonal to the ladder-type element row. One circular opening 121 is provided for each element. The shape and the installation position of the grid are not limited to those shown in FIG. For example, a large number of passage openings may be provided in the form of a mesh as openings, and a grid may be provided around or near the surface conduction electron-emitting device. The outer container terminal 122 and the grid outer terminal 123 are electrically connected to a control circuit (not shown).
[0094]
In this image forming apparatus, a modulation signal for one line of an image is simultaneously applied to a grid electrode column in synchronization with sequentially driving (scanning) the element rows one by one. Thus, irradiation of each electron beam to the phosphor can be controlled, and an image can be displayed line by line. According to this, in addition to a display device of a television broadcast, a video conference system, a display device such as a computer, it can be used as an image forming device as an optical printer configured using a photosensitive drum or the like.
[0095]
【The invention's effect】
A droplet of a solution containing a material for forming a conductive thin film between a plurality of pairs of element electrodes on a substrate is ejected by a droplet ejecting head having a discharge port diameter of Φ25 μm or less, and surface conduction type electrons are formed by the conductive thin film. In the electron source substrate manufacturing apparatus for forming the emission element group, the solution containing the material for forming the conductive thin film is a solution in which metal fine particles are dispersed in a liquid, and the metal fine particles constitute the discharge port. A new electron source substrate manufacturing device that can be used stably without causing the ejection port of the ejection head to be scratched or worn so that the ejection performance does not deteriorate because the ejection material of the ejection head is made of a softer material did it.
[0096]
In the solution used in the electron source substrate manufacturing apparatus as described above, the material for forming the conductive thin film contained in the solution is made of metal fine particles softer than the member constituting the discharge port. Thus, the ejection port of the ejection head of such a novel electron source substrate manufacturing apparatus is not scratched or worn to cause deterioration of the ejection performance, so that the electron source substrate can be manufactured stably. became.
[0097]
In the electron source substrate manufactured by the above-described electron source substrate manufacturing apparatus, the conductive thin film is a thin film obtained by volatilizing a solvent component after the droplet is applied, and the thin film is formed of the electron source substrate manufacturing apparatus. Since it is manufactured to contain metal particles that are softer than the members that make up the ejection port of the ejection head, the ejection port of the ejection head is not scratched or worn, causing no deterioration in the ejection performance. Thus, an electron source substrate having a high-quality electron-emitting device can be obtained.
[0098]
Further, by using an electron source substrate having a high-quality surface conduction electron-emitting device pattern and excellent electron-emitting device characteristics, a high-quality image display device can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a configuration of a flat surface conduction electron-emitting device according to an embodiment of the present invention.
FIG. 2 is a schematic diagram for explaining a method of manufacturing the surface conduction electron-emitting device shown in FIG.
FIG. 3 is a configuration diagram illustrating an example of an apparatus for manufacturing an electron source substrate according to the present invention.
FIG. 4 is a diagram for explaining an example of the configuration of a droplet applying apparatus to which the present invention can be applied.
5 is a schematic configuration diagram of a main part of a discharge head unit of the droplet applying device of FIG. 4;
FIG. 6 is a view showing an example of an ejection head used in the apparatus for manufacturing a surface conduction electron-emitting device according to the present invention.
FIG. 7 is a diagram showing an example of a voltage waveform in an energization forming process that can be employed for manufacturing a surface conduction electron-emitting device according to the present invention.
FIG. 8 is a schematic diagram showing an example of a matrix-disposed electron source substrate to which the present invention can be applied.
FIG. 9 is a diagram for explaining an example of a basic configuration of a display panel of an image forming apparatus using a matrix arrangement type electron source substrate to which the present invention can be applied.
FIG. 10 is a schematic diagram illustrating a configuration example of a fluorescent film used in an image forming apparatus to which the present invention can be applied.
FIG. 11 is a block diagram illustrating an example of a drive circuit for performing display on the image forming apparatus in accordance with an NTSC television signal.
FIG. 12 is a schematic view showing an example of a ladder-type arrangement type electron source substrate to which the present invention can be applied.
FIG. 13 is a diagram illustrating an example of a basic configuration of a display panel of an image forming apparatus using a ladder-type arrangement type electron source substrate to which the present invention can be applied.
FIG. 14 is a diagram illustrating an example of a conventional electron-emitting device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Substrate, 2, 3 ... Element electrode, 4 ... Conductive thin film, 5 ... Electron emission part, 10 ... Electron source substrate, 11 ... Discharge head unit (ejection head), 12 ... Carriage, 13 ... Substrate holding stand, 14 ... substrate, 15 ... supply tube, 16 ... signal supply cable, 17 ... ejection head control box, 18 ... X direction scan motor of carriage 12, 19 ... Y direction scan motor of carriage 12, 20 ... computer, 21 ... control box, 22 (22X1, 22Y1, 22X2, 22Y2): substrate positioning / holding means, 30: ejection head unit, 31: head alignment control mechanism, 32: detection optical system, 33: inkjet head, 34: head alignment fine movement mechanism, 35 ... Control computer, 36 ... Image identification mechanism, 37 ... XY direction scanning mechanism, 3 ... Position detection mechanism, 39 ... Position correction control mechanism, 40 ... Inkjet head drive / control mechanism, 41 ... Optical axis, 42 ... Droplet, 43 ... Droplet landing position, 50 ... Ejection head (inkjet head), 51 ... Heat generation Body substrate, 52: lid substrate, 53: silicon substrate used for producing heating element substrate 51, 54: individual electrode, 55: common electrode, 56: heating element, 57: solution inlet, 58: nozzle, 59: groove, Reference numeral 60: concave region, 71: electron source substrate, 72: X-direction wiring, 73: Y-direction wiring, 74: surface conduction electron-emitting device, 75: connection, 81: rear plate, 82: support frame, 83: glass substrate 84, fluorescent film, 85, metal back, 86, face plate, 88, envelope, 91, black conductive material, 92, phosphor, 101, image display panel, 102, scanning circuit, 103, control circuit 104, a shift register, 105, a line memory, 106, a synchronizing signal separation circuit, 107, a modulation signal generator, Vx and Va, a DC voltage source, 108, a common wiring composed of Dx1 to Dx10 connected to the electron-emitting device 74, 110: electron source substrate, 111: electron emitting element, 112: common wiring, 120: grid electrode, 121: opening, 122: terminal outside the container, 123: terminal outside the grid container.

Claims (4)

A droplet of a solution containing a material for forming a conductive thin film between a plurality of pairs of element electrodes on a substrate is ejected by a droplet ejecting head having a discharge port diameter of Φ25 μm or less, and surface conduction type electrons are formed by the conductive thin film. In the electron source substrate manufacturing apparatus for forming the emission element group, the solution containing the material for forming the conductive thin film is a solution in which metal fine particles are dispersed in a liquid, and the metal fine particles constitute the discharge port. An electron source substrate manufacturing apparatus, which is made of a material that is softer than a member to be made. A droplet of a solution containing a material for forming a conductive thin film between a plurality of pairs of element electrodes on a substrate is ejected by a droplet ejecting head having a discharge port diameter of Φ25 μm or less, and surface conduction type electrons are formed by the conductive thin film. In the solution used in the electron source substrate manufacturing apparatus for forming the emission element group, the material for forming the conductive thin film contained in the solution is a metal fine particle softer than the member constituting the discharge port. Features solution. A droplet of a solution containing a material for forming a conductive thin film between a plurality of pairs of element electrodes on a substrate is ejected by a droplet ejecting head having a discharge port diameter of Φ25 μm or less, and surface conduction type electrons are formed by the conductive thin film. In the electron source substrate manufactured by the electron source substrate manufacturing apparatus that forms the emission element group, the conductive thin film is a thin film obtained by volatilizing a solvent component after the droplet is applied, and the thin film constitutes the discharge port. An electron source substrate comprising metal fine particles softer than a member to be formed. 4. An electron source substrate according to claim 3, having a face plate disposed opposite to the electron source substrate, mounted with a phosphor, and having substantially the same shape and size as the electron source substrate. Image display device.

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