JP3631091B2

JP3631091B2 - Method for manufacturing electrophoretic display device

Info

Publication number: JP3631091B2
Application number: JP2000081921A
Authority: JP
Inventors: 勉池田; 信貴浮ヶ谷
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2000-03-23
Filing date: 2000-03-23
Publication date: 2005-03-23
Anticipated expiration: 2020-03-23
Also published as: JP2001264824A

Description

【０００１】
【発明の属する技術分野】
本発明は、電気泳動表示装置の製造方法に関するものである。更に詳しくは、電気泳動粒子が電極間を移動することにより表示が行われる電気泳動表示装置の製造方法に関する。
【０００２】
【従来の技術】
近年、情報機器の発達に伴い、低消費電力且つ薄型の表示装置のニーズが増しており、これらニーズに合わせた表示装置の研究、開発が盛んに行われている。中でも液晶表示装置は、液晶分子の配列を電気的に制御し液晶の光学的特性を変化させる事ができ、上記のニーズに対応できる表示装置として活発な開発が行われ商品化さてれいる。
【０００３】
しかしながら、これらの液晶表示装置では、画面を見る角度や反射光による画面上の文字の見づらさや、光源のちらつき・低輝度等から生じる視覚への負担が未だ十分に解決されていない。この為、視覚への負担の少ない表示装置の研究が盛んに検討されている。
【０００４】
低消費電力、眼への負担軽減などの観点から反射型表示装置が期待されている。その１つとして、ＨａｒｏｌｄＤ．Ｌｅｅｓ等により発明された電気泳動表示装置（米国特許第３６１２７５８号明細書）が知られている。他にも、特開平９−１８５０８７号公報に電気泳動表示装置が開示されている。
【０００５】
上記従来の電気泳動表示装置及びその動作原理を図３に示す。この電気泳動表示装置３５は、帯電した泳動粒子３３と着色色素が溶解された絶縁性液体３４からなる分散層と、この分散層を挟んで対峙する一組の電極３１、３２からなっている。電極３１、３２を介して分散層に電圧を印加することにより、泳動粒子３３を粒子自身が持つ電荷と反対極性の電極に引き寄せるものである。表示はこの泳動粒子３３の色と、泳動粒子３３の色相と異なる着色色素が溶解された絶縁性液体３４の色によって行われる。
【０００６】
つまり、第１の電極３１を負極に、第２の電極３２を正極にした場合、正電荷泳動粒子３３が観測者に近い第１の電極３１の表面に移動し、第１の電極３１に付着し、泳動粒子３３の色が表示される（図３（ｂ）参照）。
【０００７】
逆に、第１の電極３１を正極、第２の電極３２を負極した場合、正電荷泳動粒子３３が観測者から遠い第２の電極３２表面に移動し、第２の電極３２に付着し、絶縁性液体３４内に含まれる着色色素の色が表示される（図３（ａ）参照）。
【０００８】
最近、新規な構造を有する電気泳動表示装置が報告されている（特開平１１−２０２８０４号公報）。この電気泳動表示装置は、従来のものと異なり帯電泳動粒子を基板に対して水平方向に移動させて表示を行っている。帯電泳動粒子を駆動させるための電極は一方の基板に積層して形成されており、表示は表示面からみた電極面積の違いによる泳動粒子の広がり方によって明暗を出す。この方法の特徴としては、帯電泳動粒子の広がり方を利用した表示なので、分散液に透明なものを使用できる。そのためカラーフィルター層などを利用することにより、比較的容易にカラー化することができる。また、二つの電極を片側の基板に作製するので、二つの電極の位置合わせの問題や配線などの実装が簡便となる。
【０００９】
電気泳動表示装置での表示は、分散液中に分散した帯電泳動粒子の濃度に大きく依存するため、高品位な表示を得るためには帯電泳動粒子を表示面全体に均一に分散配置させる必要がある。従来型の電気泳動表示装置に帯電泳動粒子を分散させる装置としては、以下の二つの方法がある。
【００１０】
第一は、２枚の基板を一定のギャップを持たせて貼り合わせたものを減圧にした後、基板を帯電泳動粒子を分散させた分散液中に浸け、常圧に戻してギャップ間に帯電泳動粒子を分散させた分散液を注入する装置である（特開平１１−３８８９８号公報）。
【００１１】
第二は、一方の電極が形成された片側基板を、対向電極が形成されている流体貯蔵器に設置して、帯電泳動粒子が分散された懸濁媒体を注入後、一定の電界をかけて帯電泳動粒子を片側基板の電極上に付着させる装置である。この装置は図４に示される装置である（特表平８−５０２５９９号公報）。
【００１２】
【発明が解決しようとする課題】
上記の特開平１１−３８８９８号公報では、基板間のギャップが大きい場合は問題ないが、ギャップを小さくしていくと帯電泳動粒子の流れが分散液の流れに対して悪くなる現象が現れ、注入口近辺の帯電泳動粒子の濃度が高くなってしまい、均一分散が難しくなるという問題点があった。
【００１３】
一方、特表平８−５０２５９９号公報の方法では、図４に示す装置４１を用いて、基板４２の全面に渡って帯電泳動粒子を付着させることはできる。しかしながら、帯電泳動粒子の付着量は基板３２の電極と装置側の電極４３のギャップ長に大きく依存するため、フレキシブルな基板を電気泳動表示装置用の基板として用いた揚合、帯電泳動粒子の濃度分布は不均一となってしまうという問題点があった。さらに、この方法では、帯電泳動粒子を付着させる基板４２の面積と同じ面積の電極４３を装置側に用意しなければならず、量産性、製造コストの面で大きな問題であった。
【００１４】
本発明は、上記問題点を解決するためになされたものであり、電気泳動表示装置の製造に際し、２枚の基板間のギャップが非常に小さい場合、あるいはフレキシブル基板などを用いた場合においても、分散液中の帯電泳動粒子を各表示素子内に容易に均一配置できる高品位な電気泳動表示装置の製造方法を提供することを目的とするものである。
【００１５】
【課題を解決するための手段】
即ち、本発明の製造方法は、帯電泳動粒子と、該帯電泳動粒子が分散された分散媒と、電極が形成された基板を少なくとも有する電気泳動表示装置の製造方法であって、
（１）該帯電泳動粒子が分散された分散液を第１の容器に入れる工程と、
（２）該帯電泳動粒子を含まない分散液を第２の容器に入れる工程と、
（３）第１及び第２の容器中の分散液を攪拌する工程と、
（４）該電極の形成された基板を基板保持手段に設置し電極に電圧を印加する工程と、
（５）第１の容器中の帯電泳動粒子を含む分散液をノズルを通して基板面上に噴霧し、電極上に該帯電泳動粒子を堆積させる工程と、
（６）第２の容器中の帯電泳動粒子を含まない分散液をノズルを通して基板面上に噴霧する工程と
を有することを特徴とする。
【００１６】
本発明の電気泳動表示装置の製造方法に用いる製造装置は、帯電泳動粒子と、該帯電泳動粒子が分散された分散媒と、電極が形成された基板を有する電気泳動表示装置を製造するための装置であって、該基板を保持する基板保持手段と、該基板上に形成された電極に電圧を印加する手段と、該電極に帯電泳動粒子が分散された分散液を噴射して帯電泳動粒子を電極上に堆積させる手段を有する。
上記の本発明の製造装置においては、さらに、帯電泳動粒子の濃度の異なる二つ以上の分散液を噴射する手段を有することを特徴とする。
さらに、帯電泳動粒子の濃度の異なる二つ以上の分散液の少なくとも一つが、帯電泳動粒子を含まない分散液であることを特徴とする。
【００１７】
さらに、帯電泳動粒子が分散された分散液を噴射する手段が、基板に対して走査して噴射できる機能を有することを特徴とする。
さらに、帯電泳動粒子が分散された分散液を噴射する手段が、分散液を噴霧できる機能を有することを特徴とする。
【００１８】
さらに、基板保持手段が、基板を搬送する機能と基板を揺動、回転する機構を持つことを特徴とする。
さらに、製造装置が、帯電泳動粒子が分散された分散液の濃度測定手段を有することを特徴とする。
さらに、製造装置が、基板上に集められた帯電泳動粒子の濃度を測定する手段を有することを特徴とする。
さらに、電極に電圧を印加する手段が、極性の正負を切り替えながら連続的に行うことを特徴とする。
【００１９】
本発明の製造装置によれば、同一基板上に二つの相対する電極が形成された基板に対して、帯電泳動粒子を均一に配置させることができ、しかも基板と対向する位置に装置側の電極を配置する必要がないため、同時に多くの基板に対して帯電泳動粒子の付着工程を行うことができ、量産性、製造コストの面で大変優れている。また、帯電泳動粒子が分散された分散液を噴射するノズルを基板に対して走査させながら噴射することによって、新鮮な帯電泳動粒子が分散された分散液を常に基板表面に供給することが可能となり、均一性向上にさらに有効となる。
【００２０】
【発明の実施の形態】
以下、本発明を詳細に説明する。
図１は本発明の電気泳動表示装置の製造装置の一例を示す概略断面図である。本発明の電気泳動表示装置の製造装置１１は、基板１２を保持する基板保持手段１３と、基板上に形成されている電極に電圧を印加する電圧印加手段１４と、帯電泳動粒子１５を分散させた分散液１６を噴射するための手段であるノズル１７およびポンプ１８を有する。また、散布された分散液１６を保持する第１の容器１９と、電極上に集められた帯電泳動粒子１５の濃度を検出する光学濃度検出手段１１０と、分散液１６中の帯電泳動粒子１５の濃度を測定する濃度検出手段１１１と、これらの手段を集中して制御する制御手段１１２を有する。基板保持手段１３は基板１２の搬送、揺動させることができる機能を有する。さらに、帯電泳動粒子を含まないあるいは濃度の低い分散液１１３を散布するためのノズル１１４およびポンプ１１５、そして散布された分散液１１３を保持する第２の容器１１６とを有する。第１、第２の容器には、撹件装置１１７を設てもよい。
【００２１】
第１および第２の容器１９，１１６の材料は、帯電泳動粒子１５及び分散液１６、１１３中に影響する不純物を溶出しない材料なら、硝子、各種樹脂、金属などどのようなものを用いてもよい。
【００２２】
基板保持手段１３は、基板１２を確実に保持できる機能を有し、好ましくは搬送機能を有する。さらに好ましくは、保持した基板１２を揺動させる機能を有する。揺動は、基板１２を前後、左右、上下、回転等、どのような動きでもかまわない。基板保持手段１３は、基板１２を１枚あるいは複数枚を保持することができる。分散液の噴射中の基板の保持角度は、水平であっても垂直であっても、斜めであってもかまわない。
【００２３】
使用可能な基板材料としては、ガラス、硬質の厚膜プラスチック材料に加えて、ポリエチレンテレフタレート、ポリイミド、ポリカーボネート、ポリフェニレンサルファイド等の薄膜のフィルムで厚さが数十μｍ程度のものまで使用できる。このような薄膜且つフレキシブルな基板を使用できるのは、対向電極を用いる必要が無いため、基板間ギャップを考慮する必要がないためである。
【００２４】
電極印加手段１４は、基板１２に形成されている電極に電圧を印加するものであり、通常は電圧０〜３００Ｖ位を印加する。また電極に対して、交流、直流ともに印加することができるが、好ましくは交流印加を行う。交流の場合、周波数に特に制限はないが、通常は０．０１から５０Ｈｚ程度を用いる。電圧印加波形には特に制限はない。電圧、周波数、印加波形などの電圧印加条件を変えることにより、帯電泳動粒子の堆積量を容易にコントロールすることが可能である。
【００２５】
電極上に集められた帯電泳動粒子１５の濃度を検出する光学濃度検出手段１１０は、基板上の電極に交流電圧を印加して帯電泳動粒子１５を駆動させた際の光学濃度を検出するものである。検出方法としては、光学濃度を測れるものであればどのようなものでもよい。
【００２６】
分散液１６中の帯電泳動粒子１５の濃度を測定する濃度検出手段１１１は、第１の容器１９に設置される。基板１２への帯電泳動粒子１５の堆積によって低下する分散液１６中の帯電泳動粒子１５の濃度を検出する。検出方法としては、濃度を測れるものであればどのようなものでもよい。この濃度検出手段は、第２の容器１１６にも設置されていてもよい。
【００２７】
撹拌手段１１７としては、液を撹拌できるものならばどのようなものでもよい。通常はスターラーなどを用いて撹拌するが、液送ポンプなどによる液循環を利用してもよい。
第２の容器には、好ましくは帯電泳動粒子を除去するためのフィルター１１８を設置する。
【００２８】
上記の各手段を集中して制御する制御手段１１２としては、通常コンピューター等を使用する。基板の保持、搬送、揺動の制御、電圧印加条件の制御、帯電泳動粒子濃度の検出、補正など、所望の帯電泳動粒子を電極上に堆積させるための制御を集中的に行う機能を有する。
【００２９】
電気泳動表示装置は、本装置を用いて次のように作製することができる。
第１の容器には、帯電泳動粒子を分散させた分散液を満たす。第２の容器には、帯電泳動粒子を含まない分散液を満たす。基板保持手段には、特開平１１−２０２８０４号公報で開示されている方法によって作製した基板を設置する。この基板上には二つの電極が積層されており、この電極と電圧印加回路をつなぎ、電極間に交流電圧を印加する。
【００３０】
次に、基板に対して帯電泳動粒子を分散させた分散液をノズルより噴射する。ノズルは基板に対して走査させ、基板の電極面上の溶液が常に流動し、新鮮な液が常に供給されるようにする。
【００３１】
帯電泳動粒子を電極上に十分堆積した後、電圧を印加したまま基板を第２の容器上に搬送し、帯電泳動粒子を含まない、あるいは十分低濃度な分散液をノズルより走査させながら噴射する。この操作により、過剰な帯電泳動粒子、帯電の不十分な帯電泳動粒子等を除去して、各表示素子内に特性の揃った帯電泳動粒子を均一配置することができる。またこの操作では、ノズルからの分散液噴射を用いずに、基板を第２の容器に直接投入してもかまわない。この場合、第２の容器内の分散液は適度に撹拌しておくことが好ましい。
【００３２】
図２は本発明の電気泳動表示装置の製造装置の他の例を示す概略断面図であり、基板を第２の容器に直接投入する操作により、過剰な帯電泳動粒子、帯電の不十分な帯電泳動粒子等を除去する装置を示す。
【００３３】
次に、基板濃度検出手段により、電極上のコントラストを判定する。コントラストが十分に取れていた場合は操作を終了し、第２の基板の接着等表示装置組み立ての後工程に移る。コントラスト不足や均一性が低いと判断された場合は、帯電泳動粒子の付着工程、不揃い粒子の除去工程は複数回行ってもよい。
【００３４】
上記の表示装置組み立ての後工程は、具体的には、泳動用分散媒の補充、表示面側基板による封着、及び電気回路の設置及び接続等を行い、電気泳動表示装置を得る。
【００３５】
【実施例】
以下に、本発明の実施例を説明する。
【００３６】
実施例１
図１に本発明の製造装置を用いて電気泳動表示装置を作製した。
脂肪族炭化水素を主原料とする分散液（商品名：アイソパー、エクソン社製）中に平均粒径１〜２μｍ程度の黒色帯電泳動粒子及び荷電制御剤を分散させた液体を第１の容器に入れた。正荷電制御剤としては、ナフテン酸金属塩（コバルト、マンガン、鉄等）、オクテン酸ジルコニウムなどが用いられ、負荷電制御剤としては、レシチン、石油スルフォン酸カルシウム、アルキルベンゼンスルフォン酸カルシウム、ジオクチルスルフォン酸ソーダ、アルキルアラニンなどが用いられる。
【００３７】
次に、帯電泳動粒子を含まない分散液を第２の容器にいれた。第１及び第２の容器は、それぞれマグネッチックスターラーで分散液を撹拌した。基板には、縦３００ｍｍ、横２００ｍｍ、厚さ１２０μｍからなる基板を用いた。電極の形成された基板を基板保持手段に設置し、電極を電圧印加回路に接続した。電圧は、±８Ｖの矩形波を周波数１Ｈｚで印加した。
【００３８】
この基板に対して、第１の容器に入れられている帯電泳動粒子を含む分散液をノズルを通して基板面上に噴霧した。噴霧は基板上を走査しながら行った。噴霧は２分間行い、電極上に帯電泳動粒子を堆積させた。
【００３９】
これらの工程中、第１の容器中の帯電泳動粒子濃度を濃度検出手段により常に測定した。帯電泳動粒子が堆積した後、基板に電圧印加を続けながら第２の容器に移し、基板に対して、第２の容器に入れられている帯電泳動粒子を含まない分散液をノズルを通して基板面上に噴霧した。噴霧は基板上を走査しながら行った。噴霧は３分間行い、過剰な帯電泳動粒子、帯電の不十分な帯電泳動粒子等を除去して、各表示素子内に特性の揃った帯電泳動粒子を均一に配置した。噴霧中は、フィルターにより分散液中の帯電泳動粒子の除去を行った。
【００４０】
この状態で、帯電泳動粒子の濃度を光学濃度検出手段によって測定した。測定の結果、十分なコントラストが得られたので帯電泳動粒子の堆積を終了した。これらの工程管理はすべて制御装置を用いて行った。堆積終了後、帯電泳動粒子および分散液を挟むように他の透明基板を電極が形成された基板に対して貼りあわせた。この基板間のギャップは３０μｍとした。さらに、後工程として電気回路の設置及び接続等を行い、電気泳動表示装置を完成した。
【００４１】
作製した電気泳動表示装置の表示を行ったところ、非常に小さいギャップでありながら、面内のコントラスト分布は非常に均一であった。
【００４２】
実施例２
脂肪族炭化水素を主原料とする分散液（商品名：アイソパー、エクソン社製）中に平均粒径１〜２μｍ程度の黒色帯電泳動粒子及び荷電制御剤を分散させた液体を第１の容器に入れた。次に、帯電泳動粒子を含まない分散液を第２の容器にいれた。第１及び第２の容器は、それぞれマグネッチックスターラーで分散液を撹拌した。電極の形成された基板を基板保持手段に設置し、電極を電圧印加回路に接続した。電圧は、±８０Ｖの矩形波を周波数１Ｈｚで印加した。
【００４３】
この基板に対して、第１の容器に入れられている帯電泳動粒子を含む分散液をノズルを通して基板面上に液状のまま噴射した。噴射は基板上を走査しながら行った。噴射は１分間行い、電極上に帯電泳動粒子を堆積させた。
【００４４】
これらの工程中、第１の容器中の帯電泳動粒子の濃度を濃度検出手段により常に測定した。帯電泳動粒子を堆積した後、基板に電圧印加を続けながら第２の容器に移し、基板に対して、第２の容器に入れられている帯電泳動粒子を含まない分散液をノズルを通して基板面上に噴射した。噴射は基板上を走査しながら行った。噴射は２分間行い、過剰な帯電泳動粒子、帯電の不十分な帯電泳動粒子等を除去して、各表示素子内に特性の揃った帯電泳動粒子を均一に配置した。噴射中は、フィルターにより分散液中の帯電泳動粒子を除去を行った。
【００４５】
この状態で、帯電泳動粒子の濃度を光学濃度検出手段によって測定した。測定の結果、十分なコントラストが得られたので帯電泳動粒子の堆積を終了した。これらの工程管理はすべて制御装置を用いて行った。堆積終了後、帯電泳動粒子および分散液を挟むように他の透明基板を電極が形成された基板に対して貼りあわせた。この基板間のギャップは３０μｍとした。さらに、後工程を続けて電気泳動表示装置を完成した。
【００４６】
作製した電気泳動表示装置の表示を行ったところ、非常に小さいギャップでありながら、面内のコントラスト分布は非常に均一であった。
【００４７】
実施例３
図２に本発明の製造装置を用いて電気泳動表示装置を作製した。
実施例１と同様に電極上に帯電泳動粒子を堆積させた。次に、電圧印加を続けながら、基板を帯電泳動粒子を含まない分散液を満たした第２の容器に浸漬した。分散液は、緩やかに撹拌させた。撹拌中は、フィルターにより分散液中の帯電泳動粒子の除去を行った。浸漬は３分間行い、過剰な帯電泳動粒子、帯電の不十分な帯電泳動粒子等を除去して、各表示素子内に特性の揃った帯電泳動粒子を均一に配置した。
【００４８】
この状態で、帯電泳動粒子の濃度を光学濃度検出手段によって測定した。測定の結果、十分なコントラストが得られたので帯電泳動粒子の堆積を終了した。これらの工程管理はすべて制御装置を用いて行った。堆積終了後、帯電泳動粒子および分散液を挟むように他の透明基板を電極が形成された基板に対して貼りあわせた。この基板間のギャップは３０μｍとした。さらに、後工程を続けて電気泳動表示装置を完成した。
【００４９】
作製した電気泳動表示装置の表示を行ったところ、非常に小さいギャップでありながら、面内のコントラスト分布は非常に均一であった。
【００５０】
【発明の効果】
以上、詳細に述べたように、本発明の製造方法を用いると、２枚の基板間のギャップが非常に小さい場合、あるいはフレキシブル基板などを用いた場合においても、分散液中の帯電泳動粒子を各表示素子内に容易に均一配置でき、高品位な電気泳動表示装置を作製することができる。さらに、装置側に対向する電極を必要としないため、量産性、製造コストの面でも従来装置に比べて非常に優れている。
【図面の簡単な説明】
【図１】本発明の電気泳動表示装置の製造装置の一例を示す概略断面図である。
【図２】本発明の電気泳動表示装置の製造装置の他の例を示す概略断面図である。
【図３】従来の電気泳動型表示装置の原理を示す説明図である。
【図４】従来の電気泳動型表示装置の製造装置の原理を示す説明図である。
【符号の説明】
１１電気泳動表示装置の製造装置
１２基板
１３基板保持手段
１４電圧印加手段
１５帯電泳動粒子
１６分散液
１７、１１４ノズル
１８、１１５液送ポンプ
１９第１の容器
１１０光学濃度検出手段
１１１濃度検出手段
１１２制御手段
１１３分散液
１１６第２の容器
１１７撹拌手段
１１８フィルター
３１、３２電極
３３泳動粒子
３４絶縁性液体
３５電気泳動表示装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing an electrophoretic display device. More specifically, the present invention relates to a method for manufacturing an electrophoretic display device in which display is performed by moving electrophoretic particles between electrodes.
[0002]
[Prior art]
In recent years, with the development of information equipment, the need for low power consumption and thin display devices is increasing, and research and development of display devices that meet these needs are being actively conducted. In particular, liquid crystal display devices can change the optical characteristics of liquid crystals by electrically controlling the arrangement of liquid crystal molecules, and are actively developed and commercialized as display devices that can meet the above needs.
[0003]
However, in these liquid crystal display devices, the visual burden caused by the angle at which the screen is viewed, the difficulty of seeing characters on the screen due to reflected light, the flickering of the light source, low luminance, etc. has not been sufficiently solved. For this reason, research on display devices with less visual burden has been actively studied.
[0004]
Reflective display devices are expected from the viewpoints of low power consumption and reduced burden on the eyes. As one of them, Harold D.C. An electrophoretic display device (US Pat. No. 3,612,758) invented by Lees et al. Is known. In addition, an electrophoretic display device is disclosed in Japanese Patent Laid-Open No. 9-185087.
[0005]
The conventional electrophoretic display device and its operating principle are shown in FIG. The electrophoretic display device 35 includes a dispersion layer made of an insulating liquid 34 in which charged electrophoretic particles 33 and colored pigments are dissolved, and a pair of electrodes 31 and 32 facing each other with the dispersion layer interposed therebetween. By applying a voltage to the dispersion layer through the electrodes 31 and 32, the migrating particles 33 are attracted to the electrodes having the opposite polarity to the electric charge of the particles themselves. The display is performed by the color of the migrating particles 33 and the color of the insulating liquid 34 in which a coloring pigment different from the hue of the migrating particles 33 is dissolved.
[0006]
That is, when the first electrode 31 is the negative electrode and the second electrode 32 is the positive electrode, the positively charged electrophoretic particles 33 move to the surface of the first electrode 31 close to the observer and adhere to the first electrode 31. Then, the color of the migrating particles 33 is displayed (see FIG. 3B).
[0007]
Conversely, when the first electrode 31 is the positive electrode and the second electrode 32 is the negative electrode, the positively charged electrophoretic particles 33 move to the surface of the second electrode 32 far from the observer and adhere to the second electrode 32, The color of the coloring pigment contained in the insulating liquid 34 is displayed (see FIG. 3A).
[0008]
Recently, an electrophoretic display device having a novel structure has been reported (Japanese Patent Laid-Open No. 11-202804). Unlike the conventional electrophoretic display device, the electrophoretic display device performs display by moving charged electrophoretic particles in the horizontal direction with respect to the substrate. The electrodes for driving the charged electrophoretic particles are formed by being laminated on one of the substrates, and the display is bright and dark depending on how the electrophoretic particles spread due to the difference in electrode area as viewed from the display surface. As a feature of this method, since the display uses the way of spreading of the electrophoretic particles, a transparent liquid can be used. Therefore, it can be colored relatively easily by using a color filter layer or the like. In addition, since the two electrodes are formed on one substrate, the problem of alignment between the two electrodes and the mounting of wiring and the like are simplified.
[0009]
Since the display on the electrophoretic display device greatly depends on the concentration of the charged electrophoretic particles dispersed in the dispersion, it is necessary to disperse the charged electrophoretic particles uniformly over the entire display surface in order to obtain a high-quality display. is there. There are the following two methods for dispersing electrophoretic particles in a conventional electrophoretic display device.
[0010]
First, after reducing the pressure of the two substrates bonded together with a certain gap, the substrate is immersed in a dispersion liquid in which charged electrophoretic particles are dispersed, and returned to normal pressure to be charged between the gaps. This is an apparatus for injecting a dispersion liquid in which migrating particles are dispersed (Japanese Patent Laid-Open No. 11-38898).
[0011]
Secondly, one side substrate on which one electrode is formed is placed in a fluid reservoir in which a counter electrode is formed, a suspension medium in which charged electrophoretic particles are dispersed is injected, and then a certain electric field is applied. This is an apparatus for adhering charged electrophoretic particles onto an electrode on one side substrate. This apparatus is the apparatus shown in FIG. 4 (Japanese Patent Publication No. 8-502599).
[0012]
[Problems to be solved by the invention]
In the above Japanese Patent Laid-Open No. 11-38898, there is no problem when the gap between the substrates is large, but as the gap is reduced, the phenomenon that the flow of the charged electrophoretic particles becomes worse than the flow of the dispersion appears. There has been a problem that the concentration of the charged electrophoretic particles in the vicinity of the entrance becomes high and uniform dispersion becomes difficult.
[0013]
On the other hand, in the method disclosed in JP-A-8-502599, charged electrophoretic particles can be attached to the entire surface of the substrate 42 using the apparatus 41 shown in FIG. However, since the amount of the charged electrophoretic particles adhering greatly depends on the gap length between the electrode of the substrate 32 and the electrode 43 on the apparatus side, the concentration of the charged electrophoretic particles using a flexible substrate as the substrate for the electrophoretic display device. There is a problem that the distribution becomes non-uniform. Furthermore, in this method, an electrode 43 having the same area as the area of the substrate 42 to which the charged electrophoretic particles are attached must be prepared on the apparatus side, which is a big problem in terms of mass productivity and manufacturing cost.
[0014]
The present invention has been made to solve the above problems, and when manufacturing an electrophoretic display device, even when a gap between two substrates is very small, or when using a flexible substrate, An object of the present invention is to provide a method for producing a high-quality electrophoretic display device in which charged electrophoretic particles in a dispersion can be easily and uniformly arranged in each display element.
[0015]
[Means for Solving the Problems]
That is, the manufacturing method of the present invention is a method of manufacturing an electrophoretic display device having at least charged electrophoretic particles, a dispersion medium in which the charged electrophoretic particles are dispersed, and a substrate on which an electrode is formed.
(1) placing the dispersion liquid in which the charged electrophoretic particles are dispersed in a first container;
(2) placing the dispersion containing no charged electrophoretic particles into a second container;
(3) stirring the dispersion in the first and second containers;
(4) installing the substrate on which the electrode is formed on the substrate holding means and applying a voltage to the electrode;
(5) spraying the dispersion containing charged electrophoretic particles in the first container onto the substrate surface through a nozzle, and depositing the charged electrophoretic particles on the electrode;
(6) A step of spraying the dispersion liquid containing no charged electrophoretic particles in the second container onto the substrate surface through a nozzle.
[0016]
A manufacturing apparatus used in the method for manufacturing an electrophoretic display device of the present invention is for manufacturing an electrophoretic display device having a charged electrophoretic particle, a dispersion medium in which the charged electrophoretic particle is dispersed, and a substrate on which an electrode is formed. An apparatus comprising: a substrate holding means for holding the substrate; a means for applying a voltage to an electrode formed on the substrate; and a charged electrophoretic particle by ejecting a dispersion liquid in which charged electrophoretic particles are dispersed on the electrode Means for depositing on the electrode.
The manufacturing apparatus of the present invention described above further includes means for injecting two or more dispersions having different concentrations of charged electrophoretic particles.
Further, at least one of the two or more dispersions having different concentrations of the charged electrophoretic particles is a dispersion containing no charged electrophoretic particles.
[0017]
Further, the means for ejecting the dispersion liquid in which the charged electrophoretic particles are dispersed has a function of scanning and ejecting the substrate.
Further, the means for ejecting the dispersion liquid in which the charged electrophoretic particles are dispersed has a function of spraying the dispersion liquid.
[0018]
Further, the substrate holding means has a function of transporting the substrate and a mechanism for swinging and rotating the substrate.
Further, the manufacturing apparatus includes a concentration measuring unit for the dispersion liquid in which the charged electrophoretic particles are dispersed.
Furthermore, the manufacturing apparatus has means for measuring the concentration of the charged electrophoretic particles collected on the substrate.
Furthermore, the means for applying a voltage to the electrodes is continuously performed while switching between positive and negative polarities.
[0019]
According to the manufacturing apparatus of the present invention, the charged electrophoretic particles can be uniformly arranged on the substrate on which two opposing electrodes are formed on the same substrate, and the electrode on the device side is located at a position facing the substrate. Since it is not necessary to arrange the electrophoretic particles simultaneously on a large number of substrates, it is very excellent in terms of mass productivity and manufacturing cost. In addition, it is possible to always supply a dispersion liquid, in which freshly charged electrophoretic particles are dispersed, to the substrate surface by spraying while scanning the substrate with a nozzle that injects a dispersion liquid in which charged electrophoretic particles are dispersed. This is further effective in improving uniformity.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
FIG. 1 is a schematic sectional view showing an example of an apparatus for manufacturing an electrophoretic display device of the present invention. The electrophoretic display device manufacturing apparatus 11 of the present invention includes a substrate holding means 13 for holding a substrate 12, a voltage applying means 14 for applying a voltage to an electrode formed on the substrate, and charged electrophoretic particles 15 dispersed therein. The nozzle 17 and the pump 18 which are means for injecting the dispersion liquid 16 are provided. Further, the first container 19 that holds the dispersed dispersion 16, the optical density detection means 110 that detects the concentration of the charged electrophoretic particles 15 collected on the electrode, and the charged electrophoretic particles 15 in the dispersion 16. It has density detecting means 111 for measuring the density and control means 112 for controlling these means in a concentrated manner. The substrate holding means 13 has a function capable of transporting and swinging the substrate 12. Furthermore, it has a nozzle 114 and a pump 115 for spraying the dispersion liquid 113 containing no charged electrophoretic particles or having a low concentration, and a second container 116 for holding the dispersed liquid 113. A stirring device 117 may be provided in the first and second containers.
[0021]
The first and second containers 19 and 116 may be made of any material such as glass, various resins, and metals as long as they do not elute impurities affecting the charged electrophoretic particles 15 and the dispersions 16 and 113. Good.
[0022]
The substrate holding means 13 has a function of securely holding the substrate 12, and preferably has a transport function. More preferably, it has a function of swinging the held substrate 12. The swinging may be any movement such as back and forth, left and right, up and down, and rotation of the substrate 12. The substrate holding means 13 can hold one or a plurality of substrates 12. The holding angle of the substrate during ejection of the dispersion liquid may be horizontal, vertical, or oblique.
[0023]
As a usable substrate material, in addition to glass and a hard thick film plastic material, a thin film such as polyethylene terephthalate, polyimide, polycarbonate, polyphenylene sulfide and the like having a thickness of about several tens of μm can be used. The reason why such a thin film and flexible substrate can be used is that it is not necessary to use a counter electrode, and therefore it is not necessary to consider a gap between substrates.
[0024]
The electrode applying means 14 applies a voltage to the electrodes formed on the substrate 12, and normally applies a voltage of about 0 to 300V. Further, although both alternating current and direct current can be applied to the electrode, alternating current is preferably applied. In the case of alternating current, the frequency is not particularly limited, but usually about 0.01 to 50 Hz is used. There is no particular limitation on the voltage application waveform. By changing voltage application conditions such as voltage, frequency, and applied waveform, the amount of charged electrophoretic particles deposited can be easily controlled.
[0025]
The optical density detecting means 110 for detecting the concentration of the charged electrophoretic particles 15 collected on the electrodes detects the optical density when the charged electrophoretic particles 15 are driven by applying an AC voltage to the electrodes on the substrate. is there. Any detection method may be used as long as the optical density can be measured.
[0026]
A concentration detector 111 for measuring the concentration of the charged electrophoretic particles 15 in the dispersion 16 is installed in the first container 19. The concentration of the charged electrophoretic particles 15 in the dispersion liquid 16 that is lowered by the deposition of the charged electrophoretic particles 15 on the substrate 12 is detected. Any detection method may be used as long as the concentration can be measured. This concentration detection means may also be installed in the second container 116.
[0027]
Any stirring means 117 may be used as long as the liquid can be stirred. Usually, stirring is performed using a stirrer or the like, but liquid circulation using a liquid feed pump or the like may be used.
The second container is preferably provided with a filter 118 for removing charged electrophoretic particles.
[0028]
A computer or the like is normally used as the control means 112 that controls the above means in a concentrated manner. It has a function of intensively performing control for depositing desired charged electrophoretic particles on the electrode, such as control of holding, transporting and swinging the substrate, control of voltage application conditions, detection and correction of charged electrophoretic particle concentration.
[0029]
An electrophoretic display device can be manufactured as follows using this device.
The first container is filled with a dispersion liquid in which charged electrophoretic particles are dispersed. The second container is filled with a dispersion containing no charged electrophoretic particles. The substrate produced by the method disclosed in Japanese Patent Application Laid-Open No. 11-202804 is installed on the substrate holding means. Two electrodes are stacked on the substrate, and this electrode is connected to a voltage application circuit to apply an AC voltage between the electrodes.
[0030]
Next, a dispersion liquid in which charged electrophoretic particles are dispersed with respect to the substrate is ejected from a nozzle. The nozzle is scanned with respect to the substrate so that the solution on the electrode surface of the substrate always flows and fresh liquid is always supplied.
[0031]
After the charged electrophoretic particles are sufficiently deposited on the electrode, the substrate is transported to the second container while a voltage is applied, and the dispersion liquid containing no charged electrophoretic particles or having a sufficiently low concentration is ejected while being scanned from the nozzle. . By this operation, excess charged electrophoretic particles, insufficiently charged electrophoretic particles and the like can be removed, and charged electrophoretic particles having uniform characteristics can be uniformly arranged in each display element. In this operation, the substrate may be directly put into the second container without using the dispersion liquid jet from the nozzle. In this case, it is preferable that the dispersion in the second container is appropriately stirred.
[0032]
FIG. 2 is a schematic cross-sectional view showing another example of the apparatus for manufacturing an electrophoretic display device according to the present invention. When the substrate is directly placed in the second container, excessively charged electrophoretic particles and insufficiently charged An apparatus for removing electrophoretic particles and the like is shown.
[0033]
Next, the contrast on the electrode is determined by the substrate concentration detecting means. If the contrast is sufficiently high, the operation is terminated, and the process proceeds to a subsequent process of assembling the display device such as bonding of the second substrate. If it is determined that the contrast is insufficient or the uniformity is low, the step of attaching charged electrophoretic particles and the step of removing irregular particles may be performed a plurality of times.
[0034]
Specifically, the post-process for assembling the display device described above performs replenishment of the electrophoretic dispersion medium, sealing with the display surface side substrate, and installation and connection of an electric circuit to obtain an electrophoretic display device.
[0035]
【Example】
Examples of the present invention will be described below.
[0036]
Example 1
In FIG. 1, an electrophoretic display device was manufactured using the manufacturing apparatus of the present invention.
A liquid in which black charged electrophoretic particles having an average particle diameter of about 1 to 2 μm and a charge control agent are dispersed in a dispersion liquid (trade name: Isopar, manufactured by Exxon) containing an aliphatic hydrocarbon as a main raw material is placed in the first container. I put it in. Naphthenic acid metal salts (cobalt, manganese, iron, etc.), zirconium octenoate, etc. are used as positive charge control agents, and lecithin, petroleum calcium calcium sulfonate, calcium alkylbenzene sulfonate, dioctyl sulfonic acid as negative charge control agents. Soda, alkylalanine and the like are used.
[0037]
Next, a dispersion containing no charged electrophoretic particles was placed in a second container. In each of the first and second containers, the dispersion was stirred with a magnetic stirrer. As the substrate, a substrate having a length of 300 mm, a width of 200 mm, and a thickness of 120 μm was used. The substrate on which the electrode was formed was placed on the substrate holding means, and the electrode was connected to a voltage application circuit. As the voltage, a rectangular wave of ± 8 V was applied at a frequency of 1 Hz.
[0038]
A dispersion containing charged electrophoretic particles contained in a first container was sprayed onto the substrate surface through a nozzle. Spraying was performed while scanning over the substrate. Spraying was performed for 2 minutes to deposit charged electrophoretic particles on the electrode.
[0039]
During these steps, the charged electrophoretic particle concentration in the first container was always measured by the concentration detection means. After the charged electrophoretic particles are deposited, the substrate is transferred to the second container while applying a voltage to the substrate, and the dispersion liquid not containing the charged electrophoretic particles contained in the second container is passed through the nozzle onto the substrate surface. Sprayed on. Spraying was performed while scanning over the substrate. Spraying was carried out for 3 minutes to remove excess charged electrophoretic particles, insufficiently charged electrophoretic particles and the like, and uniformly arrange charged electrophoretic particles having uniform characteristics in each display element. During spraying, the charged electrophoretic particles in the dispersion were removed by a filter.
[0040]
In this state, the concentration of the charged electrophoretic particles was measured by an optical density detector. As a result of the measurement, a sufficient contrast was obtained, so that the deposition of the charged electrophoretic particles was finished. All of these process managements were performed using a control device. After the deposition was completed, another transparent substrate was bonded to the substrate on which the electrodes were formed so as to sandwich the charged electrophoretic particles and the dispersion liquid. The gap between the substrates was 30 μm. In addition, an electrical circuit was installed and connected as a post-process, and an electrophoretic display device was completed.
[0041]
When the produced electrophoretic display device was displayed, the in-plane contrast distribution was very uniform although it was a very small gap.
[0042]
Example 2
A liquid in which black charged electrophoretic particles having an average particle diameter of about 1 to 2 μm and a charge control agent are dispersed in a dispersion liquid (trade name: Isopar, manufactured by Exxon) containing an aliphatic hydrocarbon as a main raw material is placed in the first container. I put it in. Next, a dispersion containing no charged electrophoretic particles was placed in a second container. In each of the first and second containers, the dispersion was stirred with a magnetic stirrer. The substrate on which the electrode was formed was placed on the substrate holding means, and the electrode was connected to a voltage application circuit. As the voltage, a rectangular wave of ± 80 V was applied at a frequency of 1 Hz.
[0043]
A dispersion containing charged electrophoretic particles contained in a first container was sprayed onto the substrate as it was on the substrate surface through the nozzle. The ejection was performed while scanning over the substrate. The jetting was performed for 1 minute, and charged electrophoretic particles were deposited on the electrode.
[0044]
During these steps, the concentration of the charged electrophoretic particles in the first container was always measured by the concentration detection means. After the charged electrophoretic particles are deposited, the electrophoretic particles are transferred to the second container while continuing to apply a voltage to the substrate, and the dispersion liquid not containing the charged electrophoretic particles contained in the second container is passed through the nozzle onto the substrate surface. Injected into. The ejection was performed while scanning over the substrate. The jetting was performed for 2 minutes to remove excess charged electrophoretic particles, insufficiently charged charged electrophoretic particles, and the like, and uniformly arranged charged electrophoretic particles having uniform characteristics in each display element. During spraying, the charged electrophoretic particles in the dispersion were removed by a filter.
[0045]
In this state, the concentration of the charged electrophoretic particles was measured by an optical density detector. As a result of the measurement, a sufficient contrast was obtained, so that the deposition of the charged electrophoretic particles was finished. All of these process managements were performed using a control device. After the deposition was completed, another transparent substrate was bonded to the substrate on which the electrodes were formed so as to sandwich the charged electrophoretic particles and the dispersion liquid. The gap between the substrates was 30 μm. Further, the electrophoretic display device was completed by continuing the post-process.
[0046]
When the produced electrophoretic display device was displayed, the in-plane contrast distribution was very uniform although it was a very small gap.
[0047]
Example 3
In FIG. 2, an electrophoretic display device was manufactured using the manufacturing apparatus of the present invention.
In the same manner as in Example 1, charged electrophoretic particles were deposited on the electrode. Next, the substrate was immersed in a second container filled with a dispersion containing no charged electrophoretic particles while voltage application was continued. The dispersion was gently stirred. During the stirring, the charged electrophoretic particles in the dispersion were removed with a filter. The immersion was performed for 3 minutes to remove excess charged electrophoretic particles, insufficiently charged electrophoretic particles, and the like, and uniformly arrange charged electrophoretic particles with uniform characteristics in each display element.
[0048]
In this state, the concentration of the charged electrophoretic particles was measured by an optical density detector. As a result of the measurement, a sufficient contrast was obtained, so that the deposition of the charged electrophoretic particles was finished. All of these process managements were performed using a control device. After the deposition was completed, another transparent substrate was bonded to the substrate on which the electrodes were formed so as to sandwich the charged electrophoretic particles and the dispersion liquid. The gap between the substrates was 30 μm. Further, the electrophoretic display device was completed by continuing the post-process.
[0049]
When the produced electrophoretic display device was displayed, the in-plane contrast distribution was very uniform although it was a very small gap.
[0050]
【The invention's effect】
As described above in detail, when the manufacturing method of the present invention is used, the charged electrophoretic particles in the dispersion liquid can be obtained even when the gap between the two substrates is very small or when a flexible substrate is used. A high-quality electrophoretic display device can be manufactured that can be easily and uniformly arranged in each display element. Further, since no electrode facing the device side is required, it is very superior to conventional devices in terms of mass productivity and manufacturing cost.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing an example of an apparatus for manufacturing an electrophoretic display device of the present invention.
FIG. 2 is a schematic cross-sectional view showing another example of an apparatus for manufacturing an electrophoretic display device of the present invention.
FIG. 3 is an explanatory diagram showing the principle of a conventional electrophoretic display device.
FIG. 4 is an explanatory diagram showing the principle of a conventional apparatus for manufacturing an electrophoretic display device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Electrophoretic display manufacturing apparatus 12 Substrate 13 Substrate holding means 14 Voltage applying means 15 Charged electrophoretic particle 16 Dispersion liquid 17, 114 Nozzle 18, 115 Liquid feed pump 19 First container 110 Optical density detection means 111 Concentration detection means 112 Control means 113 Dispersion liquid 116 Second container 117 Stirring means 118 Filters 31 and 32 Electrode 33 Electrophoretic particles 34 Insulating liquid 35 Electrophoretic display device

Claims

A method for producing an electrophoretic display device comprising at least electrophoretic particles, a dispersion medium in which the electrophoretic particles are dispersed, and a substrate on which an electrode is formed,
(1) placing the dispersion liquid in which the charged electrophoretic particles are dispersed in a first container;
(2) placing the dispersion containing no charged electrophoretic particles into a second container;
(3) stirring the dispersion in the first and second containers;
(4) installing the substrate on which the electrode is formed on the substrate holding means and applying a voltage to the electrode;
(5) spraying the dispersion containing charged electrophoretic particles in the first container onto the substrate surface through a nozzle, and depositing the charged electrophoretic particles on the electrode;
(6) A method of manufacturing an electrophoretic display device, comprising: spraying a dispersion containing no charged electrophoretic particles in the second container onto a substrate surface through a nozzle.

The method for manufacturing an electrophoretic display device according to claim 1 , wherein the step of applying a voltage to the electrode is a step of continuously performing the polarity switching between positive and negative.

2. The manufacturing of an electrophoretic display device according to claim 1 , wherein the step of depositing the charged electrophoretic particles on the electrode is a step of depositing while measuring the concentration of the charged electrophoretic particles in the first container. Method.

After the step of spraying a dispersion liquid containing no charged particles on the substrate surface through a nozzle in the second container, according to claim, characterized in that it comprises a step of further measuring the concentration of charged particles on the electrode 2. A method for producing an electrophoretic display device according to 1 .

2. The electrophoresis according to claim 1 , further comprising a step of attaching another transparent substrate to the substrate on which the electrode is formed with the charged electrophoretic particles and the dispersion liquid interposed therebetween. Manufacturing method of display device.