JP3578074B2 - Reflective color liquid crystal device and electronic equipment using the same - Google Patents

Description

【０１１９】
（実施例２０）
実施例１６及び実施例１７では、カラーフィルタ形成部と未形成部の段差を埋める透明な層にアクリルを用いたが、ポリイミドを用いても高画質な反射型カラー液晶装置が実現できた。また、同様に透明な層にポリビニールアルコールを用いても高画質な反射型カラー液晶装置を実現できた。この結果を表２にまとめた。透明な層がない場合に比べ、画質、コントラストともに向上している。
【表２】

【０１２０】
なお、実施例１６や実施例１７では、反射板に一般的なアルミニウム反射板や銀反射板を用いたが、Ａ．Ｇ．Ｃｈｅｎ氏らが発表したホログラフィ反射板（ＳＩＤ’９５ ＤＩＧＥＳＴ、ＰＰ．１７６−１７９）を用いることもできる。
【０１２１】
（実施例２１）
図３３は、本発明の実施例２１における反射型カラー液晶装置の構造の要部を示す図である。この実施例では、カラーフィルタが総ドット数の４分の３以下の数のドットにのみ設けられている。構成を説明する。３３０１は上側偏光板、３３０２は素子基板、３３０３は液晶、３３０４は対向基板、３３０５は下側偏光板、３３０６は散乱反射板であり、対向基板３３０４上には対向電極（走査線）３３１１とカラーフィルタ３３１０を設け、素子基板３３０２上には信号線３３０７、ＭＩＭ素子３３０８、画素電極３３０９を設けた。
【０１２２】
カラーフィルタ３３１０は互いに補色の関係にある赤（図中「Ｒ」で示した）とシアン（図中「Ｃ」で示した）の２色から成っているが、一部のドットにはカラーフィルタを設けなかった。ここで用いたカラーフィルタは、実施例１と同様であり、その分光特性を図１６に示した。
【０１２３】
図３４はカラーフィルタの配置を、図３３の上方から見た形で示した図である。図中の「Ｒ」は赤フィルタを設けたドット、「Ｃ」はシアンフィルタを設けたドットを示し、「Ｗ」はカラーフィルタが無いドットを示している。全体の１／３のドットには赤フィルタを、１／３のドットにはシアンフィルタを設け、残りの１／３のドットにはカラーフィルタを設けなかった。また図３４の（ａ）（ｂ）（ｃ）（ｄ）はそれぞれ白、赤、シアン、黒を表示したときの、オンドット、オフドットの分布を示している。ハッチングを施したドットがオンドット即ち暗状態であり、ハッチングを施さないドットがオフドット即ち明状態である。このように表示を行うと、全体の２／３のドットで色表示を行うために、通常よりも明るい表示が可能になる。また色表示で中間調を表示する場合も、主としてカラーフィルタが無いドットで明るさを調整すれば、常に鮮やかな色が表示できるというメリットがある。例えば暗めの赤を表示する場合には、赤フィルタを設けたドットを全オフ、シアンフィルタを設けたドットをオンとして、カラーフィルタを設けないドットを半オンとすればよい。
【０１２４】
別のカラーフィルタ配置を図３５に示す。全体の１／４のドットには赤フィルタを、１／４のドットにはシアンフィルタを設け、残りの１／２のドットにはカラーフィルタを設けなかった。また図３５の（ａ）（ｂ）（ｃ）（ｄ）はそれぞれ白、赤、シアン、黒を表示したときの、オンドット、オフドットの分布を示している。このように表示を行うと、全体の３／４のドットで色表示を行うために、図３５のカラーフィルタ配置よりもさらに明るい表示が可能である。
【０１２５】
もう一つの例として、赤緑青３色のカラーフィルタを用いた場合の配置を図３６に示す。図中の「Ｒ」は赤フィルタを設けたドット、「Ｇ」は緑フィルタを設けたドット、「Ｂ」は青フィルタを設けたドットを示し、「Ｗ」はカラーフィルタが無いドットを示している。全体の１／６のドットには赤フィルタを、１／６のドットには緑フィルタを、１／６のドットには青フィルタを設け、残りの１／２のドットにはカラーフィルタを設けなかった。また図３６の（ａ）（ｂ）（ｃ）（ｄ）はそれぞれ白、赤、緑、青を表示したときの、オンドット、オフドットの分布を示している。このように表示を行うと、全体の４／６のドットで色表示を行うために、明るい表示が可能である。
【０１２６】
また全体の１／４のドットには赤フィルタを、１／４のドットには緑フィルタを、１／４のドットには青フィルタを設け、残りの１／４のドットにはカラーフィルタを設けない構成も可能である。このように表示を行うと、全体の１／２のドットで色表示を行うために、明るい表示が可能である。
【０１２７】
（実施例２２）
図３７は、本発明の実施例２２における反射型カラー液晶装置の構造の概略を示す図であり、（ａ）が正面図、（ｂ）が断面図である。この実施例では、カラーフィルタが有効表示領域全体に設けられている。構成を説明する。３７０１は枠ケース、３７０２は上側偏光板、３７０３は上側基板、３７０４のハッチング領域はカラーフィルタ、３７０５は下側基板、３７０６は反射板付き偏光板である。図面が煩雑になるため、透明電極、非線形素子、信号線、配向膜等は省略した。また３７１１は駆動表示領域、３７１２は有効表示領域、３７１３はカラーフィルタを設けた領域である。（ｂ）は横の断面図であるが、縦の断面図も（ｂ）と同様である。なお「駆動表示領域」と「有効表示領域」という用語は、日本電子機械工業会規格（ＥＩＡＪ）のＥＤ−２５１１Ａにおいて、それぞれ「液晶表示デバイスで表示機能を保有する領域」「駆動表示領域とそれに続く画面として有効な領域」と定義されている。つまり駆動表示領域とは液晶に電圧をかけることができる領域であり、有効表示領域とは枠ケースに隠されない液晶パネル領域全てである。
【０１２８】
実施例２２の特徴は、カラーフィルタを設けた領域３７１３が有効表示領域３７１２と同じか、または広いことにある。このように構成することにより、実施例２２の反射型カラー液晶装置は、表示が明るく見えるという利点がある。通常、透過型カラー表示では、駆動表示領域にのみカラーフィルタが設けられ、その外側の領域にはメタルか樹脂によるブラックマスクが設けられる。ところが反射型カラー表示では、メタルのブラックマスクはぎらつくため利用できない。また樹脂のブラックマスクは、もともとのカラーフィルタにブラックマスクを設けていないため、コストアップになる。かといって駆動表示領域の外側に何も設けないと、外側が明るくなり、相対的に駆動表示領域が暗く見える。そこで駆動表示領域の外側にも内側と同様のカラーフィルタを、好ましくは同じパターンで設けることが、表示を明るく見せる上で有効である。
【０１２９】
（実施例２３）
透過型カラー液晶装置では、一般にドット外にブラックマスクを設けるが、反射型カラー液晶装置にブラックマスクを設けると、高コントラストが得られる反面、表示が極端に暗くなる。特にＴＮモードやＳＴＮモードのように視差が避けられない液晶モードでは、光が入射するときと出射するときの２回ブラックマスクで吸収されるため、明るさが開口率のほぼ２乗に比例するという性質がある。従って反射型カラー液晶装置にブラックマスクを設けることは出来ないが、逆にドット外に全く光吸収体を設けないと、コントラストが著しく低下し、好ましくない。そこで本発明の実施例２３では、ドット外にブラックマスクを設けず、代わりにドット内の領域と同程度かそれよりも小さい吸収を有するカラーフィルタを設けたことを特徴とする。
【０１３０】
図３８は、本発明の実施例２３における反射型カラー液晶装置のカラーフィルタ配置を示す図である。上述したように、この実施例では、各ドットの外側の領域にブラックマスクを設けず、代わりにドット内の領域と同程度かそれよりも小さい吸収を有するカラーフィルタを設けた。基本的な構成ならびにカラーフィルタの分光特性は実施例５の図６ならびに図３と同様であるが、ドット外の領域におけるカラーフィルタの配置に工夫を凝らした。図３８において、３８０１に示した「横凸」状の領域は、対向電極と画素電極が重なっていて、液晶に電界が印加される領域であり、上述のドットに相当する。また右上から左下に斜めにハッチングを施した領域３８０２はシアンフィルタであり、クロスにハッチングを施した領域３８０３は赤フィルタである。
【０１３１】
図３８の（ａ）では、赤フィルタとシアンフィルタがドット外でぴったり接するように配置した。また（ｂ）では、ドット外にもフィルタを設けたが互いに離して配置した。また（ｃ）では、ドット外に赤フィルタを配置した。いずれもドット外の領域にドット内と同程度あるいはそれよりも小さいがゼロではない吸収を有しているため、明るくコントラストが高い表示が得られる。各々の特性は、（ａ）が白表示時の反射率３０％でコントラスト比１：１５、（ｂ）が反射率３３％でコントラスト比１：１３、（ｃ）が２９％で１：１６であった。
【０１３２】
（実施例２４）
図３９は、本発明の実施例２４における反射型カラー液晶装置のカラーフィルタ配置を示す図である。この実施例も、各ドットの外側の領域にブラックマスクを設けず、代わりにドット内の領域と同程度かそれよりも小さい吸収を有するカラーフィルタを設けたものである。基本的な構成ならびにカラーフィルタの分光特性は実施例９の図８と図１２と同様であるが、ドット外の領域におけるカラーフィルタの配置に工夫を凝らした。図３９において、３９０１に示した「横凸」状の領域は、対向電極と画素電極が重なっていて、液晶に電界が印加される領域であり、実施例２３のドットに相当する。また左上から右下に斜めにハッチングを施した領域３９０２は青フィルタであり、右上から左下に斜めにハッチングを施した領域３９０３は緑フィルタであり、クロスにハッチングを施した領域３９０４は赤フィルタである。
【０１３３】
図３９の（ａ）では、３色のフィルタをドット外にも設けたが互いに離して配置した。離す距離は、カラーフィルタ作成時の最大のアライメントずれを見越して設定した。即ち、図３９の（ｂ）は想定される最大のアライメントずれを起こした場合のカラーフィルタ配置であるが、その場合でも異なる色のカラーフィルタが互いに重なることがないようにした。カラーフィルタが重なることは、ブラックマスクが存在することと殆ど同義であるから、可能な限りこれを避けなければならない。以上のようにカラーフィルタを配置することによって、明るく高コントラストな反射型カラー表示が出来た。
【０１３４】
（実施例２５）
図４０は、本発明の実施例２５における反射型カラー液晶装置の要部を示す図である。この実施例も、各ドットの外側の領域にブラックマスクを設けず、代わりにドット内の領域と同程度かそれよりも小さい吸収を有するカラーフィルタを設けた。まず構成を説明する。４００１は上側偏光板、４００２は対向基板、４００３は液晶、４００４は素子基板、４００５は下側偏光板、４００６は散乱反射板であり、対向基板４００２上にはカラーフィルタ４００７と、対向電極（走査線）４００８を設け、素子基板４００４上には信号線４００９、画素電極４０１０、ＭＩＭ素子４０１１を設けた。このカラーフィルタは、ＰＣ等のデータディスプレイで一般的なストライプ配列である。なおカラーフィルタの分光特性は実施例９の図１２と同様である。
【０１３５】
図４１は、本発明の実施例２５における反射型カラー液晶装置のカラーフィルタ配置を示す図である。図４１において、４１０１に示した「横凸」状の領域は、対向電極と画素電極が重なっていて、液晶に電界が印加される領域であり、実施例２３のドットに相当する。また左上から右下に斜めにハッチングを施した領域４１０２は青フィルタであり、右上から左下に斜めにハッチングを施した領域４１０３は緑フィルタであり、クロスにハッチングを施した領域４１０４は赤フィルタである。
【０１３６】
図４１の（ａ）では、３色のフィルタをドット外にも設けたが、上下には連続して配置し、左右には互いに離して配置した。離す距離は、カラーフィルタ作成時の最大のアライメントずれを見越して設定した。即ち、図４１の（ｂ）は想定される最大のアライメントずれを起こした場合のカラーフィルタ配置であるが、その場合でも異なる色のカラーフィルタが互いに重なることがないようにした。以上のようにカラーフィルタを配置することによって、明るく高コントラストな反射型カラー表示が出来た。
【０１３７】
（実施例２６）
図４２は、本発明の実施例２６における反射型カラー液晶装置の構造の要部を示す断面図である。この実施例は、一対の基板の内、反射板側に位置する基板の外面に、カラーフィルタを設けた。構成を説明する。４２０１は上側偏光板、４２０２は素子基板、４２０３は液晶、４２０４は対向基板、４２０５は下側偏光板、４２０６は散乱反射板であり、素子基板４２０２上には信号線４２０７と画素電極４２０８を設け、対向基板４２０４上には対向電極（走査線）４２０９を設けた。この断面図では現れないが、信号線と画素電極はＭＩＭ素子を介してつながっている。また対向基板４２０４の反射板側表面に赤フィルタ４２１０、緑フィルタ４２１１、青フィルタ４２１２を設けた。
【０１３８】
カラーフィルタの分光特性は、もしドットの全面に設けるならば図１２に示したような、またドットの一部に設けるならばその割合に応じて図１６や図１８に示したような特性を持たせる。
【０１３９】
このようにカラーフィルタを基板の外側に設けることにより、安価なカラーフィルタを利用することができる。このカラーフィルタは別にフィルム等の上に設けておいて、後で張り合わせても良い。また特にドットの一部にだけカラーフィルタを設けることにより、組立マージンが拡大し、視角が広がるという利点がある。
【０１４０】
（実施例２７）
実施例２７では、一対の基板の内、反射板側に位置する基板の内面に、非線形素子を各ドットに対応して設けている。この実施例における反射型カラー液晶装置の構造は、実施例１の図１、実施例６の図６、実施例７の図８と同様である。その特徴は反射板側に位置する基板１０４、６０４、８０４上に、ＭＩＭ素子１１１、６１１、８１１を設けたことにある。このように配置することによって、その逆の溝成、即ち基板１０２、６０２、８０２上にＭＩＭ素子を設けた場合に比べて、不要な表面反射が減り、高いコントラストが得られた。その理由は三つある。一つは信号線１０９、６０９、８０９とＭＩＭ素子による反射がカラーフィルタ１０７、６０７、８０７によって一部吸収されることであり、二つ目は信号線自体が金属Ｔａ上に金属Ｃｒを重ねた構造であり、ＴａよりもＣｒの方が反射率が小さいことである。三つ目は反射光が液晶層１０３、６０３、８０３を通ることによって複屈折干渉による吸収が生じることである。
【０１４１】
（実施例２８）
実施例２８では、一対の基板の内、一方の基板の内面に、非線形素子を各ドットに対応して設け、これをドットの短辺と平行な方向に結線した。この実施例における反射型カラー液晶装置の全体の構造は、例えば実施例７の図８等と同様である。その特徴はＭＩＭ素子の配線方法にある。
【０１４２】
図４３は、実施例２８における反射型カラー液晶装置のＭＩＭ素子の配線方法を示す図である。４３０１は信号線、４３０２はＭＩＭ素子、４３０３は画素電極である。画素電極は各々対向基板の赤、緑、青のカラーフィルタと対応しているため、対応関係を画素電極上に「Ｒ」「Ｇ」「Ｂ」で示した。
【０１４３】
図４３の各ドットは全て縦長の形状をしており、横に並んだ３つのドットで１つの正方画素を形成している。これはパソコン用のデータディスプレイでよく見られる構成である。このとき、信号線はドットの短辺と平行、即ち横方向に配線されている。このように配線すると、配線数が少なくなり開口率が高くなるという効果があった。ここで開口率とは金属等の不透明な部分を除いた領域の占める割合である。
【０１４４】
これを従来の構成と比較する。図４４は、従来のＭＩＭ素子を用いた（透過型）カラー液晶装置の配線方法を示す図である。４４０１は信号線、４４０２はＭＩＭ素子、４４０３は画素電極である。ドットピッチは図４３と同じであり、ドットは縦長の形状をしているが、信号線はドットの長辺と平行、即ち縦方向に配線されている。このように配線すると配線数が図４３の場合の３倍になり開口率が低い。従来このような配線を行っていた理由は、一つは横長パネルでは縦方向の配線の方が距離が短いからであり、もう一つはブラックマスクを設ければ縦に配線しても横に配線しても開口率が変わらないからであった。
【０１４５】
このように開口率が高くなると、表示が明るくなる。開口率が明るさに効くこと、特に視差のある反射型構成でそれが顕著であることに関しては、既に実施例２３から２５で詳しく説明した。
【０１４６】
（実施例２９）
実施例２９では、駆動面積率が６０％以上８５％以下である。図４５は、この実施例における反射型カラー液晶装置の特性を示す。実施例２と同様の構成をとり、駆動面積率を５０％から１００％に変えた時の、駆動面積率とコントラスト、及び駆動面積率と反射率の関係を示している。ここで駆動面積率は、画素内の金属配線やＭＩＭ素子等の不透明な部分を除いた領域の中で、液晶が駆動される領域がしめる割合として定義される。横軸に駆動面積率、縦軸にコントラストと反射率をとり、４５０１は本実施例のコントラスト、４５０２は比較例のコントラスト、４５０３は本実施例のシアン表示時の反射率、４５０４は比較例のシアン表示時の反射率である。
【０１４７】
駆動面積率が６０％以上であれば１：５以上の良好なコントラストを得ることが出来る。また駆動面積率８５％以下であればシアン表示で２３％以上の良好な明るさを得ることが出来る。
【０１４８】
（実施例３０）
反射型カラー液晶装置においては、散乱反射板の特性が、明るさやコントラスト、視角特性を大きく左右する。散乱反射板には鏡面のように散乱性の弱いものから、紙のように散乱性の強いものまで各種存在し、周囲環境に応じて選択されるが、反射型カラー液晶装置向けには、明るさとコントラストを重視して散乱性の弱いものが望ましい。
【０１４９】
図４６と図４７は、本発明の実施例３０における反射型カラー液晶装置の反射板の特性を示す図である。反射板が、これにビーム光を入射したときに、その正反射方向を中心とした３０度コーンの中に８０％以上の光が反射するような散乱特性を有している。
【０１５０】
図４６において、４６０４は散乱反射板、４６０１は散乱反射板表面に４５゜の角度で入射する光、４６０２はその正反射光、４６０３は正反射を中心にした３０度コーンである。また図４７の横軸は反射光の受光角、縦軸は相対反射強度である。実施例３０の反射板は、入射光の約９５％が、図４６の３０゜コーンの中に反射する特性を有する。これが８０％未満になると、通常の室内環境のもとで、１：１０以上のコントラスト比が得られなくなる。
【０１５１】
参考のために図４８には計算機シミュレーションの結果を示した。図の横軸は図４６に示した３０度コーンの中に反射される光の割合であり、図の縦軸は明るさとコントラスト比である。光源には積分球のような完全散乱白色光を仮定し、基板法線方向に反射してくる光を計算した。明るさは標準白色板の明るさを１００％とした。このシミュレーション結果からも明らかなように３０度コーンの中に反射される光の割合が多いほど、即ち反射板の散乱度が弱いほど、明るく高コントラストな表示が得られる。但し入射光の９５％よりも大きい光が３０度コーンの中に反射されるような反射板では、視角特性が著しく狭く、実用に耐えないことが実験により確かめられている。
【０１５２】
（実施例３１）
図４９は、本発明の実施例３１における反射型カラー液晶装置の構造の要部を示す図である。反射板が半透過反射板であって、その背面にバックライトを備えている。まず構成を説明する。４９０１は上側偏光板、４９０２は対向基板、４９０３は液晶、４９０４は素子基板、４９０５は下側偏光板、４９０６は半透過反射板、４９１２はバックライトであり、対向基板４９０２上にはカラーフィルタ４９０７と、対向電極（走査線）４９０８を設け、素子基板４９０４上には信号線４９０９、画素電極４９１０、ＭＩＭ素子４９１１を設けた。またカラーフィルタは、実施例２の図３と同様の分光特性を有している。
【０１５３】
半透過反射板の反射率は、通常の散乱反射板の７割程度であるから、バックライトを点灯せずに反射モードで使用する際には、白色表示時の反射率が２４％程度に、なる。一方バックライトを点灯した透過モードでは、透過率が２２％程度になり、表面輝度４００ｃｄ／ｍ^２ といったモノクロ用のバックライトでも十分な明るさが得られる。また図３に示したようなカラーフィルタの特性では、本来透過で色を表示するには不十分であるが、半透過反射板を用いると、透過モードでも周囲光の反射で色純度が高まるという効果がある。
【０１５４】
なお半透過反射板は、入射光の８０％以上を反射することが、明るい表示を得る上で望ましい。必然的に透過モードで使用する際には暗い表示となるが、透過モードの明るさを追求することは、えてして透過表示も反射表示も不満足な結果になりやすい。透過モードは真っ暗闇でかろうじて見えれば良いと割り切る方が、市場に受け入れられやすい良いディスプレイが得られる。
【０１５５】
（実施例３２）
実施例３２では、液晶が略９０度ねじれたネマチック液晶であり、２枚の偏光板をその透過軸が各々隣接する基板のラビング方向と直交するよう配置した。この実施例における反射型カラー液晶装置の基本的な構成、およびカラーフィルタの分光特性は、実施例５の図６、図３と同様である。その特徴は、ＴＮモードのセル条件が反射型カラー液晶装置用に最適化されていることにある。
【０１５６】
図５０は、実施例３２における反射型カラー液晶装置の各軸の関係を示す図である。５０２１は液晶パネルの左右方向（長手方向）であり、５００１は上側偏光板の透過軸方向、５００２が上側に位置する対向基板のラビング方向、５００３が下側に位置する素子基板のラビング方向、５００４が下側偏光板の透過軸方向である。ここで対向基板のラビング方向と液晶パネルの左右方向がなす角度５０１１を４５゜に、上側偏光板の透過軸方向と対向基板のラビング方向がなす角度５０１２を９０゜に、液晶のツイスト角５０１３を右９０゜に、下側偏光板の透過軸方向と素子基板のラビング方向がなす角度５０１４を９０゜に設定した。このように配置すると、液晶層中心の分子が電圧印加時に観察者側（即ち図の下側）から立ち上がり、ＴＮ液晶の視角特性とも相まって、高コントラストで影の見えにくい表示が可能になる。また偏光板の透過軸が隣接基板のラビング方向と直交する配置（いわゆるＯモード）は、平行配置（いわゆるＥモード）に比べて視角方向による色変化が少なく、より好ましい。
【０１５７】
また液晶材料の複屈折率△ｎを０．１８９、セルギャップを７．１μｍにすることで、液晶セルの△ｎ×ｄを１．３４μｍに設定した。これは非選択電圧印加時に最も明るく色づきの少ない条件であって、△ｎ×ｄ＜１．３０μｍでは表示色が青っぽくなり、△ｎ×ｄ＞１．４０μｍでは表示が暗くなるという問題があり好ましくない。
【０１５８】
（実施例３３）
実施例３３では、液晶の複屈折率△ｎと、液晶層厚ｄの積△ｎ×ｄが０．３４μｍよりも大きく、０．５２μｍよりも小さい。この実施例における反射型カラー液晶装置の基本的な構成は、実施例２の図１と同様である。その特徴は、ＴＮモードのセル条件が反射型カラー液晶装置用にさらに最適化されていることにある。
【０１５９】
図５０は実施例３３における反射型カラー液晶装置の各軸の関係を示す図である。５０２１は液晶パネルの左右方向（長手方向）であり、５００１は上側偏光板の透過軸方向、５００２が上側に位置する対向基板のラビング方向、５００３が下側に位置する素子基板のラビング方向、５００４が下側偏光板の透過軸方向である。ここで対向基板のラビング方向と液晶パネルの左右方向がなす角度５０１１を４５゜に、上側偏光板の透過軸方向と対向基板のラビング方向がなす角度５０１２を９０゜に、液晶のツイスト角５０１３を右９０゜に、下側偏光板の透過軸方向と素子基板のラビング方向がなす角度５０１４を９０゜に設定した。このように配置すると、液晶層中心の分子が電圧印加時に観察者側（即ち図の下側）から立ち上がり、ＴＮ液晶の視角特性とも相まって、高コントラストで影の見えにくい表示が可能になる。また偏光板の透過軸が隣接基板のラビング方向と直交する配置（いわゆるＯモード）は、平行配置（いわゆるＥモード）に比べて視角方向による色変化が少なく、より好ましい。
【０１６０】
ここで液晶材料の複屈折率△ｎを０．０８４とし、セルギャップを変えて△ｎ×ｄの異なるパネルを作製した。
【０１６１】
図５１に△ｎ×ｄと白表示時の反射率の関係を示す。５１０１は実施例の各△ｎ×ｄに対する反射率、５１０２は比較例の各△ｎ×ｄに対する反射率を示す。測定には積分球を利用して全方位から均等に光が入射するようにして測定した。反射率は標準白色板を１００％に取った。図５１より、△ｎ×ｄが大きくなるほど視角が狭まって斜めからの入射光の利用効率が低下するために、表示が暗くなる様子が読みとれる。従って明るい表示を得る上では、△ｎ×ｄが小さい、いわゆるファーストミニマム条件を利用することが好ましい。ところがファーストミニマム条件は表示の色付きが大きいという欠点がある。そのために、従来の反射型モノクロ液晶装置では実施例３２のような、△ｎ×ｄが大きい条件を利用していた。しかしながら反射型カラー液晶装置では、カラーフィルタを調整することで少々の色付きは補正できる。実施例３３ではカラーフィルタを長波長側で高い透過率を持つように調整することで、どの△ｎ×ｄでも白は無色に近く、色付きもほとんど変らない表示を得た。
【０１６２】
△ｎ×ｄが０．４２μｍの時にもっとも高い反射率を示すが、この付近の△ｎ×ｄに対応する反射率を以下の表３に示す。
【表３】

【０１６３】
このように、△ｎ×ｄが０．３４μｍよりも大きく、０．５２μｍよりも小さくすることで明るい表示が得られる。
【０１６４】
なお△ｎ×ｄが０．４０μｍより小さい時は、視角が広いために明るい表示が得られているが、一方で正面方向の明るさが低くスポット光源下では暗く見えるため、△ｎ×ｄは０．４０μｍ以上の方が好ましい。また、０．４８μｍ以下にすることにより極端に大きな色付きを無くすことができるため、△ｎ×ｄは０．４８μｍ以下であることが好ましい。最も好ましい△ｎ×ｄは最大の明るさが得られる０．４２μｍである。
【０１６５】
（実施例３４）
本発明の実施例３４では、液晶が９０度以上ねじれたネマチック液晶であり、２枚の偏光板と少なくとも１枚の位相差フィルムを配置した。図５２は、実施例３４における反射型カラー液晶装置の要部を示す図である。まず構成を説明する。５２０１は上側偏光板、５２０２は位相差フイルム、５２０３は上側基板、５２０４は液晶、５２０５は下側基板、５２０６は下側偏光板、５２０７は散乱反射板であり、上側基板５２０３上にはカラーフィルタ５２０８と、走査電極５２０９を設け、下側基板５２０５上には信号電極５２１０を設けた。位相差フィルム５２０２はポリカーボネートの一軸延伸フィルムで、正の位相差を示す。またカラーフィルタは、実施例２の図３と同様の分光特性を有している。
【０１６６】
図５３は、実施例３４における反射型カラー液晶装置の各軸の関係を示す図である。５３２１は液晶パネルの左右方向（長手方向）であり、５３０１は上側偏光板の透過軸方向、５３０２が上側基板のラビング方向、５３０３が下側基板のラビング方向、５３０４が下側偏光板の透過軸方向、５３０５が位相差フイルムの延伸方向である。ここで上側基板のラビング方向と液晶パネルの左右方向がなす角度５３１１を３０゜に、上側偏光板の透過軸方向と位相差フィルムの延伸方向がなす角度５３１４を５４゜に、位相差フィルムの延伸方向と上側基板のラビング方向がなす角度５３１５を８０゜に、液晶のツイスト角５３１２を左２４０゜に、下側偏光板の透過軸方向と下側基板のラビング方向がなす角度５３１３を４３゜に設定した。このように配置すると、液晶層中心の分子が電圧印加時に観察者側（即ち図の下側）から立ち上がり、視角特性とも相まって、高コントラストで影の見えにくい表示が可能になる。
【０１６７】
これは、特公平３−５０２４９号公報で提案された位相差板補償型のＳＴＮモードであって、単純マトリクスでデューテイ比１／４８０までのマルチプレクス駆動ができる点に特徴がある。また実施例２と同じカラーフィルタを用いたにもかかわらず、信号線やＭＩＭ素子が不要な分だけ開口率が高く、白色表示時の反射率が３３％と、非常に明るい表示が可能である。なおコントラスト比は１：８と比較的低めだったが、色補償を行う位相差フィルムを１枚増やし、特開平６−３４８２３０号公報に開示されている手法に従って多ライン同時選択駆動を行うことにより、ＭＩＭ素子を備えた場合と同等のコントラストで、同等の色を表示することができる。
【０１６８】
（実施例３５）
本発明の実施例３４でも、液晶が９０度以上ねじれたネマチック液晶であり、２枚の偏光板と少なくとも１枚の位相差フィルムを配置した。図５５は、実施例３５における反射型カラー液晶装置の構造の要部を示す図である。まず構成を説明する。５５０１は上側偏光板、５５０２は位相差フイルム、５５０３は上側基板、５５０４は液晶、５５０５は下側基板、５５０６は下側偏光板、５５０７は散乱反射板であり、上側基板５５０３上にはカラーフィルタ５５０８と、走査電極５５０９を設け、下側基板５５０５上には信号電極５５１０を設けた。位相差フィルム５５０２はポリカーボネートの一軸延伸フィルムで、正の５８７ｎｍの位相差を有する。液晶の△ｎとセルギャップの積△ｎ×ｄは０．８５μｍである。
【０１６９】
図５３は、実施例３５における反射型カラー液晶装置の各軸の関係を示す図である。５３２１は液晶パネルの左右方向（長手方向）であり、５３０１は上側偏光板の透過軸方向、５３０２が上側基板のラビング方向、５３０３が下側基板のラビング方向、５３０４が下側偏光板の透過軸方向、５３０５が位相差フィルムの延伸方向である。ここで上側基板のラビング方向と液晶パネルの左右方向がなす角度５３１１を３０゜に、上側偏光板の透過軸方向と位相差フィルムの延伸方向がなす角度５３１４を３８゜に、位相差フィルムの延伸方向と上側基板のラビング方向がなす角度５３１５を９２゜に、液晶のツイスト角５３１２を左２４０゜に、下側偏光板の透過軸方向と下側基板のラビング方向がなす角度５３１３を５０゜に設定した。
【０１７０】
図５４は、実施例３５における反射型カラー液晶装置のカラーフィルタの分光特性を示す図である。図５４の横軸は光の波長、縦軸は透過率であり、５４０１が赤フィルタのスペクトル、５４０２が緑フィルタのスペクトル、５４０３が青フィルタのスペクトルを示している。このカラーフィルタ特性は、前記液晶装置からカラーフィルタを除いた場合のオフ状態における分光特性５４１１から、ホワイトバランスが取れるよう最適化したものである。ここで緑フィルタと青フィルタは、４５０ｎｍから６６０ｎｍの波長範囲で、５０％以上の透過率を有している。また赤フィルタの４５０ｎｍから６６０ｎｍの範囲の波長の光に対する最小透過率は、青フィルタ、緑フィルタに比べてはっきりと小さい。このような赤フィルタを用いることにより、最も人間の目にアピールする赤色を鮮やかに表示することが出来る。また赤を濃くしたことを補償する目的で、青フィルタのスペクトル５４０３をシアン色に近くした。
【０１７１】
これは、特公平３−５０２４９号公報で提案された位相差板補償型のＳＴＮモードであって、単純マトリクスでデューテイ比１／４８０までのマルチプレクス駆動ができる点に特徴がある。但し従来の位相差板補償型のＳＴＮモードは、白黒表示が出来るとは言ってもシアン色っぽい白しか出せなかった。ところが実施例３５の反射型カラー液晶装置は、カラーフィルタを最適化したことにより、従来よりもずっとニュートラルに近い白が表示できるようになった。また実施例９と特性の似たカラーフィルタを用いたにもかかわらず、信号線やＭＩＭ素子が不要な分だけ開口率が高く、白色表示時の反射率が２９％と、非常に明るい表示が可能である。
【０１７２】
（実施例３６）
本発明の実施例３６では、反射板を一対の基板間に備え、偏光板を１枚だけ配置した。図５６は、実施例３６における反射型カラー液晶装置の要部を示す図である。まず構成を説明する。５６０１は上側偏光板、５６０２は対向基板、５６０３は液晶、５６０４は素子基板であり、対向基板５６０２上にはカラーフィルタ５６０５と、対向電極（走査線）５６０６を設け、素子基板５６０４上には信号線５６０７、散乱反射板を兼ねた画素電極５６０８、ＭＩＭ素子５６０９を設けた。散乱反射板を兼ねた画素電極は、金属アルミニウムのスパッタ膜の表面に機械的、化学的手法により凹凸をつけたものを用いた。またカラーフィルタは、実施例２の図３と同様の分光特性を有している。
【０１７３】
図５７は、実施例３６における反射型カラー液晶装置の各軸の関係を示す図である。５７２１は液晶パネルの左右方向（長手方向）であり、５７０１は上側偏光板の透過軸方向、５７０２が上側基板のラビング方向、５７０３が下側基板のラビング方向である。ここで上側基板のラビング方向と液晶パネルの左右方向がなす角度５７１１を６２゜に、上側偏光板の透過軸方向と上側基板のラビング方向がなす角度５７１２を９４゜に、液晶のツイスト角５７１３を右５６゜に設定した。このように配置すると、液晶層中心の分子が電圧印加時に観察者側（即ち図の下側）から立ち上がり、視角特性とも相まって、高コントラスト表示が可能になる。
【０１７４】
これは、特開平３−２２３７１５号公報で提案された１枚偏光板型のネマチック液晶モードであって、下側偏光板を用いずに高コントラストの白黒表示ができるため、液晶と接する位置に散乱反射板を設けることができる点に特徴がある。
【０１７５】
この反射型カラー液晶装置は、白色表示時の反射率が３０％、コントラスト比が１：１０、白と赤とシアンと黒の４色表示が可能で、赤表示色はｘ＝０．３８、ｙ＝０．３１、シアン表示色はｘ＝０．２８、ｙ＝０．３２であった。その表示には全く影が生じず、視角依存性も極めて少ない。また例えば赤フィルタを通って入射した光は必ず赤フィルタを通って出射するため、色の濁りが生じず、明るく色純度の高い表示ができた。
【０１７６】
上記実施例ではＭＩＭ素子を用いたが、その代わりにＴＦＴ素子を用いることもできる。図５８は、反射板を一対の基板間に備え、偏光板を１枚だけ配置した本発明の反射型カラー液晶装置をＴＦＴ素子を用いて作成した場合の構造の要部を示す図である。まず構成を説明する。５８０１は上側偏光板、５８０２は対向基板、５８０３は液晶、５８０４は素子基板であり、対向基板５８０２上にはカラーフィルタ５８０５と、対向電極（共通電極）５８０６を設け、素子基板５８０４上にはゲート信号線５８０７、ソース信号線５８０８、ＴＦＴ素子５８０９、散乱反射板を兼ねた画素電極５８１０を設けた。ＭＩＭ素子の場合は金属配線が上下方向に走るだけであったが、ＴＦＴ素子では上下方向と左右方向に金属配線が走るため、開口率が低下する。幸いこの実施例３６では下側偏光板を必要としない。そこでＴＦＴ素子を利用する場合には、素子、信号線のレイヤー上に絶縁膜を設け、その上に改めて画素電極を兼ねる反射板を設け、コンタクトホールを通して両者を接続する手法を取ることが好ましい。
【０１７７】
（実施例３７）
実施例３７は、反射板を一対の基板間に備え、偏光板を１枚だけ配置した反射型カラー液晶装置において、前記反射板が鏡面反射板であり、かつ入射光側に位置する基板の外面に散乱板を備えたものに関するが、まず反射型モノクロ液晶装置に関する例を６つ紹介する。これらはいずれもカラーフィルタの付加により、反射型カラー液晶装置として利用できる。
【０１７８】
〈第１の例〉
図５９は、第１の例における反射型液晶装置の断面図である。まず構成を説明する。５９０ｌは散乱板、５９０２は上側偏光板、５９０３は上側基板、５９０４は上側電極、５９０５は液晶、５９０６は下側電極、５９０７は下側基板、５９０８は下側偏光板、５９０９は鏡面反射板である。液晶５９０５はセル内で９０度ねじれており、偏光板５９０２と５９０８の吸収軸は近接する界面の液晶５の遅相軸に一致するＴＮモードである。液晶５９０５の厚さｄと複屈折率△ｎの積△ｎ×ｄは０．４８μｍである。
【０１７９】
以上の構成の反射型液晶装置は、室内において、基板法線方向での白表示時の明るさが２５％、コントラストが１：１５であり、天井灯の正反射方向での白表示の明るさが４５％、コントラストが１：１２であった。正反射方向であっても散乱板の後方散乱の効果で天井灯が映り込むことがなく、高いコントラストが得られる。 このように十分なコントラストを保ちつつ正反射方向の光が有効に利用出来るために、とても明るい表示が得られる。
【０１８０】
〈第２の例〉
図６０は第２の例における反射型液晶装置Ｎｏ．１からＮｏ．３の断面図である。６００１は散乱板、６００２は上側偏光板、６００３は上側基板、６００４は上側電極、６００５は液晶、６００６は下側電極、６００７は下側基板、６００８は鏡面反射板である。
【０１８１】
図６１に第２の例における反射型液晶装置Ｎｏ．１からＮｏ．３の偏光板等の軸方向を示す。６１０１は上側偏光板６００２の透過軸方向、６１０３は上側基板６００３のラビング方向、６１０３は下側基板６００７のラビング方向であり、６１０４が上側偏光板６００２の透過軸方向６１０１の水平と成す角度θ１、６１０５が上側基板６００３のラビング方向６１０２の水平と成す角度θ２、６１０６が下側基板６００７のラビング方向６１０３の水平と成す角度θ３である。角度は反時計回りに正とし、−１８０度から１８０度で示す。
【０１８２】
図６２は第２の例における反射型液晶装置Ｎｏ．４からＮｏ．６の断面図である。６２０１は散乱板、６２０２は上側偏光板、６２０３は位相差板、６２０４は上側基板、６２０５は上側電極、６２０６は液晶、６２０７は下側電極、６２０８は下側基板、６２０９は鏡面反射板である。
【０１８３】
図６３に第２の例における反射型液晶装置Ｎｏ．４からＮｏ．６の偏光板等の軸方向を示す。６３０１は上側偏光板６２０２の透過軸方向、６３０２は位相差板６２０３の遅相軸方向、６３０３は上側基板６２０４のラビング方向、６３０４は下側基板６２０８のラビング方向であり、６３０５が上側偏光板６２０２の透過軸方向６３０１の水平と成す角度θ１、６３０６が上側基板６２０４のラビング方向６３０３の水平と成す角度θ２、６３０７が下側基板６２０８のラビング方向６３０４の水平と成す角度θ３、６３０８が位相差板６２０３の遅相軸方向６３０２の水平と成す角度θ４である。
【０１８４】
これらの角度条件と液晶セルの△ｎ×ｄ、位相差板の位相差の値を以下の表４に示す。図中△ｎ×ｄと位相差の単位はμｍである。
【表４】

【０１８５】
これらの特性を以下の表５に示す。
【表５】

第１の例と同様に十分なコントラストと明るい表示が得られる。
【０１８６】
〈第１の例、第２の例の比較例〉
図６４に比較例における反射型液晶装置の断面図を示す。６４０１は上側偏光板、６４０２は上側基板、６４０３は上側電極、６４０４は液晶、６４０５は下側電極、６４０６は下側基板、６４０７は下側偏光板、６４０８は散乱反射板である。液晶６４０４は第１の例と同様にセル内で９０度にねじっており、偏光板６４０１と６４０７の吸収軸は近接する界面の液晶５の遅相軸に一致するＴＮモードである。液晶６４０４の厚さｄと複屈折率△ｎの積△ｎ×ｄは０．４８μｍである。
【０１８７】
以上の構成の反射型液晶装置は、室内において、基板法線方向での白表示時の明るさが２８％、コントラストが１：１５であったが、天井灯の正反射方向では天井灯の映り込みのために、白表示の明るさが６２％、コントラストが１：２となり、実用に耐えなかった。
【０１８８】
〈第３の例〉
図６５は第３の例における反射型液晶装置の散乱板の特性を示す図である。第６５図において、６５０１は散乱板、６５０２は入射光、６５０３は正反射光、６５０４は正反射光６５０３を中心とした１０度コーンである。第３の例の散乱板６５０１は１０度コーン６５０３の中に入射光の５％の光が散乱する。
【０１８９】
以上の特性を持つ散乱板は、信学技報ＥＩＤ９５−１４６にあるように、媒質と異なる屈折率を持つ粒子の混入により前方散乱を作り、表面に微小な凹凸を設けて後方散乱を調整することで得た。この散乱光が１０％よりも大きいと光源の映り込みが大きくなってコントラストが低下し、逆に０．５％よりも小さくなると表示のぼけが大きくなりすぎる。
【０１９０】
また、本実施例の構成は第１の例の図５９に示した構成と同様であり、液晶５９０５はセル内で９０度にねじっており、偏光板５９０２と５９０８の吸収軸は近接する界面の液晶５９０５の遅相軸に一致するＴＮモードである。液晶５９０５の厚さｄと複屈折率△ｎの積△ｎ×ｄは０．４８μｍである。
【０１９１】
以上の構成の反射型液晶装置は、室内において、基板法線方向での白表示時の明るさが２６％、コントラストが１：１５であり、天井灯の正反射方向での白表示の明るさが４３％、コントラストが１：１３であった。
【０１９２】
〈第４の例〉
第３の例の図６５に示した散乱板を、第２の例の図６０、図６２の構成に適用した。
【０１９３】
図６１、図６３で示した各軸方向と液晶の△ｎ×ｄと位相差を第２の例と同様に設定した。特性を以下の表６に示す。
【表６】

実施例１同様に十分なコントラストと明るい表示が得られる。
【０１９４】
〈第５の例〉
図６６は第５の例における反射型液晶装置の断面図である。まず構成を説明する。６６０１は散乱板、６６０２は上側偏光板、６６０３は上側基板、６６０４は上側電極、６６０５は液晶、６６０６は下側偏光板、６６０７は下側電極兼鏡面反射板、６６０８は下側基板である。液晶６６０５はセル内で９０度にねじれており、偏光板６６０２、６６０６の吸収軸は近接する界面の液晶５の遅相軸に一致するＴＮモードである。液晶６６０５の厚さｄと複屈折率△ｎの積△ｎ×ｄは０．４８μｍである。下側電極にはアルミニウムを蒸着して、偏光板はポリイミド配向膜上に黒色２色性色素を含有させた液晶性高分子の溶液を塗布、配向させることで得た。散乱板には第３の例と同様のものを使用した。
【０１９５】
以上の構成の反射型液晶装置は、室内において基板法線方向での白表示時の明るさが２８％、コントラストが１：１８であり、天井灯の正反射方向での白表示の明るさが４４％、コントラストが１：１６であった。
【０１９６】
〈第６の例〉
図６７は第６の例における反射型液晶装置Ｎｏ．１からＮｏ．３の断面図である。６７０１は散乱板、６７０２は上側偏光板、６７０３は上側基板、６７０４は上側電極、６７０５は液晶、６７０６は下側電極兼鏡面反射板、６７０７は下側基板である。
【０１９７】
図６１に第６の例における反射型液晶装置Ｎｏ．１からＮｏ．３の偏光板等の軸方向を示す。６１０１は上側偏光板６００２の透過軸方向、６１０３は上側基板６００３のラビング方向、６１０３は下側基板６００７のラビング方向であり、６１０４が上側偏光板６００２の透過軸方向６１０１の水平と成す角度θ１、６１０５が上側基板６００３のラビング方向６１０２の水平と成す角度θ２、６１０６が下側基板６００７のラビング方向６１０３の水平と成す角度θ３である。
【０１９８】
図６８は第６の例における反射型液晶装置Ｎｏ．４からＮｏ．６の断面図である。６８０１は散乱板、６８０２は上側偏光板、６８０３は位相差板、６８０４上側基板、６８０５は上側電極、６８０６は液晶、６８０７は下側電極兼鏡面反射板、６８０８は下側基板である。
【０１９９】
図６３に第６の例における反射型液晶装置Ｎｏ．４からＮｏ．６の偏光板等の軸方向を示す。６３０１は上側偏光板６２０２の透過軸方向、６３０２は位相差板６２０３の遅相軸方向、６３０３は上側基板６２０４のラビング方向、６３０４は下側基板６２０８のラビング方向であり、６３０５が上側偏光板６２０２の透過軸方向６３０１の水平と成す角度θ１、６３０６が上側基板６２０４のラビング方向６３０３の水平と成す角度θ２、６３０７が下側基板６２０８のラビング方向６３０４の水平と成す角度θ３、６３０８が位相差板６２０３の遅相軸方向６３０２の水平と成す角度θ４である。
【０２００】
角度、液晶の△ｎ×ｄ、位相差板の位相差の条件は、第２の例で示した表４と同じである。また散乱板には第３の例と同様のものを使用した。
【０２０１】
以上の構成の反射型液晶表示素子の特性を以下の表７に示す。
【表７】

いずれも十分なコントラストと明るい表示が得られる。
【０２０２】
以上示した６つの反射型モノクロ液晶装置は、いずれもカラーフィルタの付加により反射型カラー液晶装置として利用できるが、次にその例を一つ示す。
【０２０３】
図６９は、本発明の実施例３７における反射型カラー液晶装置の要部を示した図である。６９０１は散乱板、６９０２は上側偏光板、６９０３は位相差板、６９０４は上側基板、６９０５は液晶、６９０６は下側基板、６９０７は対向電極（走査線）、６９０８は信号線、６９０９は画素電極兼鏡面反射板、６９１０はＭＩＭ素子、６９１１はカラーフィルタである。画素と画素の間隔を信号線に直交、平行の両方向共に１６０μｍとし、信号線の幅を１０μｍ、信号線と画素電極の間隙を１０μｍ、隣り合う画素電極と画素電極の間隔を１０μｍとした。
【０２０４】
図６３に偏光板等の軸方向を示す。６３０１は上側偏光板６２０２の透過軸方向、６３０２は位相差板６２０３の遅相軸方向、６３０３は上側基板６２０４のラビング方向、６３０４は下側基板６２０８のラビング方向であり、６３０５が上側偏光板６２０２の透過軸方向６３０１の水平と成す角度θ１、６３０６が上側基板６２０４のラビング方向６３０３の水平と成す角度θ２、６３０７が下側基板６２０８のラビング方向６３０４の水平と成す角度θ３、６３０８が位相差板６２０３の遅相軸方向６３０２の水平と成す角度θ４である。
【０２０５】
液晶６９０５の△ｎ×ｄは０．３３μｍ、θ１は−８２度、θ２は−７４度、θ３は７４度、θ４は９度、位相差板６９０３の位相差は０．３１μｍに設定し、信号線６９０８上も画素電極兼鏡面反射板６９０９上と同様に配向処理を施した。
【０２０６】
散乱板には第３の例と同様のものを使用した。またカラーフィルタ６９１１には平均透過率７５％のシアン（図中Ｃ）とレッド（図中Ｒ）のカラーフィルターを使用した。
【０２０７】
以上の構成の反射型液晶装置は、室内において、基板法線方向での白表示時の明るさが３０％、コントラストが１：１５であり、天井灯の正反射方向での白表示の明るさが５１％、コントラストが１：１２であった。何れも表示色はレッドがｘ＝０．３９、ｙ＝０．３２、シアンがｘ＝０．２８、ｙ＝０．３１であった。十分に色を認識でき、明るい表示である。
【０２０８】
（実施例３８）
実施例３８は、反射板を一対の基板間に備え、偏光板を１枚だけ配置したことを特徴とする反射型カラー液晶装置において、または、前記反射板が鏡面反射板であり、かつ入射光側に位置する基板の外面に散乱板を備えたことを特徴とする反射型カラー液晶装置において、金属配線上の液晶も画素部の液晶と同様に配向している反射型カラー液晶装置に関するが、まず反射型モノクロ液晶装置に関する例を２つ紹介する。これらはいずれもカラーフィルタの付加により、反射型カラー液晶装置として利用できる。
【０２０９】
〈第１の例〉
図７０は第１の例における反射型液晶装置の要部を示した図である。７００１は散乱板、７００２は上側偏光板、７００３は上側基板、７００４は液晶、７００５は下側基板、７００６は下側偏光板、７００７は鏡面反射板、７００８は対向電極（走査線）、７００９は信号線、７０１０は画素電極、７０１１はＭＩＭ素子である。液晶７００４はセル内で９０度にねじっており、偏光板７００２と７００６の吸収軸は近接する界面の液晶７００４の遅相軸に一致するＴＮモードである。液晶７００４の厚さｄと複屈折率△ｎの積△ｎ×ｄは０．４８μｍである。散乱板には実施例３７の第３の例と同様のものを使用した。
【０２１０】
画素と画素の間隔を信号線に直交、平行の両方向共に１６０μｍとし、信号線の幅を１０μｍ、信号線と画素電極の間隙を１０μｍ、隣り合う画素電極と画素電極の間隔を１０μｍとした。
【０２１１】
以上の構成の反射型液晶装置で、信号線７００９上及び対向電極７００８の画素部以外の領域も画素電極７０１０上の領域と同様にラビング処理を施して液晶を配列させたところ、室内において基板法線方向での白表示時の明るさが２３％、コントラストが１：１４であり、天井灯の正反射方向での白表示の明るさが４３％、コントラストが１：１１であった。
【０２１２】
ところで金属電極上は画素電極のＩＴＯとは塗れ性が異なるため、配向膜を塗布してもはじかれることが多い。このような場合、即ち信号線７００９上に配向処理を施さないときには、室内において基板法線方向での白表示時の明るさが１９％、コントラストが１：１４であり、天井灯の正反射方向での白表示の明るさが４０％、コントラストが１：１１であった。
【０２１３】
いずれの場合も高コントラストと非常に明るい表示を得ることが出来るが、金属配線上も配向処理することによりさらに明るい表示を得ることが出来た。
【０２１４】
〈第２の例〉
図７１は第２の例における反射型液晶装置Ｎｏ．１とＮｏ．３の要部を示した図である。７１０１は散乱板、７１０２は上側偏光板、７１０３は上側基板、７１０４は液晶、７１０５は下側基板、７１０６は鏡面反射板、７１０７は対向電極（走査線）、７１０８は信号線、７１０９は画素電極、７１１０はＭＩＭ素子である。画素と画素の間隔を信号線に直交、平行の両方向共に１６０μｍとし、信号線の幅を１０μｍ、信号線と画素電極の間隙を１０μｍ、隣り合う画素電極と画素電極の間隔を１０μｍとした。
【０２１５】
図６１に第２の例における反射型液晶装置Ｎｏ．１からＮｏ．３の偏光板等の軸方向を示す。６１０１は上側偏光板６００２の透過軸方向、６１０３は上側基板６００３のラビング方向、６１０３は下側基板６００７のラビング方向であり、６１０４が上側偏光板６００２の透過軸方向６１０１の水平と成す角度θ１、６１０５が上側基板６００３のラビング方向６１０２の水平と成す角度θ２、６１０６が下側基板６００７のラビング方向６１０３の水平と成す角度θ３である。
【０２１６】
図７２は第２の例における反射型液晶装置のＮｏ．２とＮｏ．４の要部を示した図である。７２０１は散乱板、７２０２は位相差板、７２０３は上側偏光板、７２０４は上側基板、７２０５は液晶、７２０６は下側基板、７２０７は鏡面反射板、７２０８は対向電極（走査線）、７２０９は信号線、７２１０は画素電極、７２１１はＭＩＭ素子である。画素と画素の間隔を信号線に直交、平行の両方向共に１６０μｍとし、信号線の幅を１０μｍ、信号線と画素電極の間隙を１０μｍ、隣り合う画素電極と画素電極の間隔を１０μｍとした。
【０２１７】
図６３に第２の例における反射型液晶装置Ｎｏ．４からＮｏ．６の偏光板等の軸方向を示す。６３０１は上側偏光板６２０２の透過軸方向、６３０２は位相差板６２０３の遅相軸方向、６３０３は上側基板６２０４のラビング方向、６３０４は下側基板６２０８のラビング方向であり、６３０５が上側偏光板６２０２の透過軸方向６３０１の水平と成す角度θ１、６３０６が上側基板６２０４のラビング方向６３０３の水平と成す角度θ２、６３０７が下側基板６２０８のラビング方向６３０４の水平と成す角度θ３、６３０８が位相差板６２０３の遅相軸方向６３０２の水平と成す角度θ４である。
【０２１８】
散乱板には実施例３７の第３の例と同様のものを使用した。
以上の構成の反射型液晶装置で、Ｎｏ．１とＮｏ．２は画素部以外の領域にも配向処理を施したものであり、Ｎｏ．３とＮｏ．４は画素部だけに配向処理を施したものとした。
【０２１９】
液晶７２０５の△ｎ×ｄ、偏光板等の角度、位相差板の位相差を以下の表８に示す。
【表８】

【０２２０】
またその特性を以下の表９に示す。
【表９】

【０２２１】
いずれの例も高コントラストで明るい表示を得ることが出来るが、画素部以外の領域にも配向処理を施すことによりさらに明るい表示を得ることが出来た。
【０２２２】
（実施例３９）
実施例３９は、表示がノーマリホワイト型である反射型カラー液晶装置に関するが、まず反射型モノクロ液晶装置に関する例を紹介する。これはカラーフィルタの付加により、反射型カラー液晶装置として利用できる。
【０２２３】
図５９は、実施例３９の反射型液晶装置Ｎｏ．１、Ｎｏ．２の断面図である。まず構成を説明する。５９０１は散乱板、５９０２は上側偏光板、５９０３は上側基板、５９０４は上側電極、５９０５は液晶、５９０６は下側電極、５９０７は下側基板、５９０８は下側偏光板、５９０９は鏡面反射板である。液晶５９０５はセル内で９０度にねじっており、Ｎｏ．１は偏光板５９０２、５９０８の吸収軸が近接する界面の液晶５９０５の遅相軸に一致、Ｎｏ．２は偏光板５９０２の吸収軸、５９０８の吸収軸がそれぞれ近接する界面の液晶５９０５の遅相軸に一致するＴＮモードである。液晶５９０５の厚さｄと複屈折率△ｎの積△ｎ×ｄは０．４８μｍである。
散乱板には実施例３７の第３の例と同様のものを使用した。
【０２２４】
図７３は実施例３７の反射型液晶装置の電圧透過率特性を示す図である。ここで７３０１はＮｏ．１の電圧に対する透過率の変化の様子であり、７３０２はＮｏ．２の電圧に対する透過率の変化の様子である。Ｎｏ．１はノーマリーホワイト、Ｎｏ．２はノーマリーブラックの表示である。
【０２２５】
以上の構成の反射型液晶装置は、Ｎｏ．１は室内において、基板法線方向での白表示時の明るさが２５％、コントラストが１：１５であり、天井灯の正反射方向での白表示の明るさが４５％、コントラストが１：１２であった。Ｎｏ．２は室内において、基板法線方向での白表示時の明るさが２３％、コントラストが１：１５であり、天井灯の正反射方向での白表示の明るさが４２％、コントラストが１：１３であった。
【０２２６】
双方共に十分なコントラストと明るい表示が得られるが、ノーマリーホワイトモードの方がより明るい表示が得られる。これは画素外の領域が明るさに寄与するためであり、また斜め方向から入射した光を透過しやすい視角特性を有するためである。
【０２２７】
（実施例４０）
以上の実施例１から３９における反射型カラー液晶装置で表示を行う際には、従来の透過型カラー液晶装置では存在しなかった問題が生じる。それは単独のドットでは十分に発色せず、色を表示するためにはある程度広い領域にわたって同一色を表示する必要があるということである。これはカラーフィルターの色が淡いことや、液晶層と反射板との間に距離があって（実施例３６から３９を除く）、隣のドットの色が混じりやすいことなどが原因である。
【０２２８】
従って白地に赤い文字を表示するような使い方よりは、白地に黒色の文字を表示してその背景の一部を赤にするような使い方、即ちマーカーのような使い方が適している。しかしながら単独の画素で十分に発色しないということは、逆に言えばカラー液晶装置でありながら容易に白黒表示ができるということでもある。
【０２２９】
実施例４０の反射型カラー液晶装置は、１ドットで１画素を構成することを特徴とする。画素とは表示に必要な機能を実現できる最小単位のことであり、通常のカラー液晶装置では、１画素は赤緑青各１ドット計３ドットで構成される。従って４８０×６４０画素のＶＧＡの表示を行うためには、４８０×６４０×３ドットが必要であった。シアンと赤の２色カラーフィルタを用いる場合には、４８０×６４０×２ドットが必要であった。しかしながら実施例４０は、カラー液晶装置でありながら４８０×６４０画素でＶＧＡ表示を行うことができる。
【０２３０】
実施例４０の構成は、例えば実施例５等と同様である。ただ表示を行う場合に次のような工夫をする。図７４に一例を示したので、この図に沿って説明する。ここには１６×４８画素が図示されている。（ａ）はカラーフィルタの配列を示す図であり、赤（「Ｒ」で示した）とシアン（「Ｃ」で示した）がモザイク状に並んでいる。また（ｂ）と（ｃ）はオンドットとオフドットの分布を示す図である。オンドットは暗表示であるためハッチングで示した。（ｂ）の表示は、カラーフィルタ配列を無視して「ＬＣＤ」という形にオンさせたものであるが、先に述べたようにこの反射型カラー液晶装置は単独のドットでは十分に発色しないため、白地に黒く「ＬＣＤ」と表示されて見える。従ってＶＧＡの解像度で白黒表示が可能である。一方（ｃ）の表示は、（ｂ）の背景のシアン色ドットだけをオンしたもので、赤字に黒く「ＬＣＤ」と表示されて見える。このように１０ドットあるいはそれよりも広い面積にわたって同一色を表示すると、色を表示することが可能になる。
【０２３１】
このようなマーカーとしての使い方以外にも、例えば地図情報を表示する場合に、特定の路線だけを着色することも、道路幅が数ドットあれば可能になる。またパソコン画面のアイコン等もある程度の面積があるため、カラー表示することが可能である。
【０２３２】
（実施例４１）
以上の実施例１から４０における反射型カラー液晶装置を電子機器のディスプレイとして採用した。
【０２３３】
図７５は、実施例１から４０における反射型カラー液晶装置を採用した電子機器の一例を示す図である。これはいわゆるＰＤＡ（Ｐｅｒｓｏｎａｌ Ｄｉｇｉｔａｌ Ａｓｓｉｓｔａｎｔ）であって、携帯情報端末の一種である。７５０１は反射型カラー液晶装置であり、その前面にはペン入力のためのタブレットを装着した。ＰＤＡ用のディスプレイには、従来反射型モノクロ液晶装置、あるいは透過型カラー液晶装置が利用されていた。これらを反射型カラー液晶装置で置き換えることによって、前者に比べるとカラー表示による情報量の飛躍的増大というメリットが、また後者に比べると電池寿命の長期化と小型軽量化というメリットがあった。
【０２３４】
図７６は、実施例４１の電子機器において、周囲光を観察者に効率よく反射できるよう、表示部が本体に対し動かせるよう取り付けた電子機器の一例を示す図である。これはいわゆるデジタルスチルカメラである。７６０１は反射型カラー液晶装置であって、本体に対してその角度が変えられるように取り付けてある。また図示されていないが、レンズはこの反射型カラー液晶装置取り付け部の裏側にある。デジタルスチルカメラ用のディスプレイには、従来透過型カラー液晶装置が利用されていた。これを反射型カラー液晶装置に置き換えることによって、電池寿命の長期化と小型化はもちろんのこと、直射日光下での視認性が格段に向上した。なぜならば、透過型カラー液晶装置はバックライトの明るさが限られているため直射日光下で表面反射が大きくなると見えにくくなるが、反射型カラー液晶装置は周囲光が明るくなるほど表示も明るくなるからである。この周囲光を有効に利用するためにも、液晶装置の角度が変えられるように取り付けることが有効である。
【０２３５】
反射型カラー液晶装置は、上記電子機器以外にもパームトップＰＣやサブノートＰＣ、ノートＰＣ、ハンディーターミナル、カムコーダ、液晶テレビ、ゲーム機、電子手帳、携帯電話、ページャーといった携帯性を重視する様々な電子機器に応用できる。
【図面の簡単な説明】
【図１】本発明の実施例１〜４、２７、２９、３３における反射型カラー液晶装置の構造の要部を示す図である。
【図２】本発明の実施例１における反射型カラー液晶装置のカラーフィルタの分光特性を示す図である。
【図３】本発明の実施例２、３、５、２３、２９、３１、３２、３４、３６、４０における反射型カラー液晶装置のカラーフィルタの分光特性を示す図である。
【図４】本発明の実施例３における反射型カラー液晶装置において、素子基板の厚さを変化させたときのコントラストの変化をプロットした図である。
【図５】本発明の実施例４における反射型カラー液晶装置のカラーフィルタの分光特性を示す図である。
【図６】本発明の実施例５、６、２３、２７、３２、４０における反射型カラー液晶装置の構造の要部を示す図である。
【図７】本発明の実施例６における反射型カラー液晶装置のカラーフィルタの分光特性を示す図である。
【図８】本発明の実施例７、９、２４、２７、２８における反射型カラー液晶装置の構造の要部を示す図である。
【図９】本発明の実施例７における反射型カラー液晶装置のカラーフィルタの分光特性を示す図である。
【図１０】本発明の実施倒８、１０における反射型カラー液晶装置の構造の要部を示す図である。
【図１１】本発明の実施例８における反射型カラー液晶装置のカラーフィルタの分光特性を示す図である。
【図１２】本発明の実施例９、２４、２５、２６における反射型カラー液晶装置のカラーフィルタの分光特性を示す図である。
【図１３】本発明の実施例１０における反射型カラー液晶装置のカラーフィルタの分光特性を示す図である。
【図１４】本発明の実施例１０における反射型カラー液晶装置において、カラーフィルタの厚みを変化させたときの平均透過率の変化をプロットした図である。
【図１５】本発明の実施例１１、１２、１５における反射型カラー液晶装置の構造の要部を示す図である。
【図１６】本発明の実施例１１、２１、２６における反射型カラー液晶装置のカラーフィルタの分光特性を示す図である。
【図１７】本発明の実施例１１における反射型カラー液晶装置において、カラーフィルタを設ける面積の割合を変化させたときの平均透過率の変化をプロットした図である。
【図１８】本発明の実施例１２、２６における反射型カラー液晶装置のカラーフィルタの分光特性を示す図である。
【図１９】本発明の実施例１２における反射型カラー液晶装置において、カラーフィルタを設ける面積の割合を変化させたときの平均透過率の変化をプロットした図である。
【図２０】本発明の実施例１３、１５における反射型カラー液晶装置の構造の要部を示す図である。
【図２１】本発明の実施例１４、１５における反射型カラー液晶装置の構造の要部を示す図である。
【図２２】本発明の実施例１５における反射型カラー液晶装置の電圧反射率特性を示す図である。
【図２３】本発明の実施例１６における反射型カラー液晶装置のカラーフィルタ基板の構造を示す図である。
【図２４】本発明の実施例１６における反射型カラー液晶装置の構造の要部を示す図である。
【図２５】本発明の実施例１６における反射型カラー液晶装置のカラーフィルタの分光特性を示す図である。
【図２６】本発明の実施例１６、１７における反射型カラー液晶装置のカラーフィルタの１ドット内の平均分光特性を示す図である。
【図２７】本発明の実施例１６で言及した比較例における反射型カラー液晶装置のカラーフィルタ基板の構造を示す図である。
【図２８】本発明の実施例１７における反射型カラー液晶装置のカラーフィルタ基板の構造を示す図である。
【図２９】本発明の実施例１７における反射型カラー液晶装置のカラーフィルタの分光特性を示す図である。
【図３０】本発明の実施例１７における反射型カラー液晶装置のカラーフィルタの分光特性を示す図である。
【図３１】本発明の実施例１７における反射型カラー液晶装置のカラーフィルタの分光特性を示す図である。
【図３２】本発明の実施例１８における反射型カラー液晶装置のカラーフィルタの配置を示す図である。
【図３３】本発明の実施例２１における反射型カラー液晶装置の構造の要部を示す図である。
【図３４】本発明の実施例２１における反射型カラー液晶装置のカラーフィルタの配置を示す図である。
【図３５】本発明の実施例２１における反射型カラー液晶装置のカラーフィルタの配置を示す図である。
【図３６】本発明の実施例２１における反射型カラー液晶装置のカラーフィルタの配置を示す図である。
【図３７】本発明の実施例２２における反射型カラー液晶装置の構造の概略を示す図である。
【図３８】本発明の実施例２３における反射型カラー液晶装置のカラーフィルタの配置を示す図である。
【図３９】本発明の実施例２４における反射型カラー液晶装置のカラーフィルタの配置を示す図である。
【図４０】本発明の実施例２５における反射型カラー液晶装置の構造の要部を示す図である。
【図４１】本発明の実施例２５における反射型カラー液晶装置のカラーフィルタの配置を示す図である。
【図４２】本発明の実施例２６における反射型カラー液晶装置の構造の要部を示す図である。
【図４３】本発明の実施例２８における反射型カラー液晶装置のＭＩＭ素子の配線方法を示す図である。
【図４４】本発明の実施例２８で言及した比較例における反射型カラー液晶装置のＭＩＭ素子の配線方法を示す図である。
【図４５】本発明の実施例２９における反射型カラー液晶装置において、駆動面積を変化させたときのコントラストと反射率の変化をプロットした図である。
【図４６】本発明の実施例３０における反射型カラー液晶装置の反射板の散乱特性を説明するための図である。
【図４７】本発明の実施例３０における反射型カラー液晶装置の反射板の散乱特性を示す図である。
【図４８】本発明の実施例３０における反射型カラー液晶装置において、３０度コーンの中に反射される光の割合を変化させたときの明るさとコントラスト比をプロットした図である。
【図４９】本発明の実施例３１における反射型カラー液晶装置の構造の要部を示す図である。
【図５０】本発明の実施例３２、３３における反射型カラー液晶装置の各軸の関係を示す図である。
【図５１】本発明の実施例３３における反射型カラー液晶装置において、液晶セルの△ｎ×ｄを変化させたときの白表示の反射率の変化をプロットした図である。
【図５２】本発明の実施例３４における反射型カラー液晶装置の構造の要部を示す図である。
【図５３】本発明の実施例３４、３５における反射型カラー液晶装置の各軸の関係を示す図である。
【図５４】本発明の実施例３５における反射型カラー液晶装置のカラーフィルタの分光特性を示す図である。
【図５５】本発明の実施例３５における反射型カラー液晶装置の構造の要部を示す図である。
【図５６】本発明の実施例３６における反射型カラー液晶装置の構造の要部を示す図である。
【図５７】本発明の実施例３６における反射型カラー液晶装置の各軸の関係を示す図である。
【図５８】本発明の実施例３６における反射型カラー液晶装置の構造の要部を示す図である。
【図５９】本発明の実施例３７、３９における反射型カラー液晶装置の構造の要部を示す図である。
【図６０】本発明の実施例３７における反射型カラー液晶装置の構造の要部を示す図である。
【図６１】本発明の実施例３７、３８における反射型カラー液晶装置の各軸の関係を示す図である。
【図６２】本発明の実施例３７における反射型カラー液晶装置の構造の要部を示す図である。
【図６３】本発明の実施例３７、３８における反射型カラー液晶装置の各軸の関係を示す図である。
【図６４】本発明の実施例３７における反射型カラー液晶装置の構造の要部を示す図である。
【図６５】本発明の実施例３７における反射型カラー液晶装置の散乱板の特性を示す図である。
【図６６】本発明の実施例３７における反射型カラー液晶装置の構造の要部を示す図である。
【図６７】本発明の実施例３７における反射型カラー液晶装置の構造の要部を示す図である。
【図６８】本発明の実施例３７における反射型カラー液晶装置の構造の要部を示す図である。
【図６９】本発明の実施例３７における反射型カラー液晶装置の構造の要部を示す図である。
【図７０】本発明の実施例３８における反射型カラー液晶装置の構造の要部を示す図である。
【図７１】本発明の実施例３８における反射型カラー液晶装置の構造の要部を示す図である。
【図７２】本発明の実施例３８における反射型カラー液晶装置の構造の要部を示す図である。
【図７３】本発明の実施例３９における反射型カラー液晶装置の電圧透過率特性を示す図である。
【図７４】本発明の実施例４０における反射型カラー液晶装置の表示法の一例を示す図である。
【図７５】本発明の実施例４１における反射型カラー液晶装置を用いた電子機器の一例を示す図である。
【図７６】本発明の実施例４１における反射型カラー液晶装置を用いた電子機器の一例を示す図である。
【図７７】反射型カラー液晶装置に特有の視差の問題について説明した図である。
【図７８】従来の透過型カラー液晶装置のカラーフィルタの分光特性を示す図である。
【図７９】内田龍男氏らの論文（ＩＥＥＥ Ｔｒａｎｓａｃｔｉｏｎｓ ｏｎ Ｅｌｅｃｔｒｏｎ Ｄｅｖｉｃｅｓ，Ｖｏｌ．ＥＤ−３３，Ｎｏ．８，ｐｐ．１２０７−１２１１（１９８６））のＦｉｇ．８で提案されていたカラーフィルタの分光特性を示す図である。
【図８０】三ツ井精一氏らの論文（ＳＩＤ９２ ＤＩＧＥＳＴ，ｐｐ．４３７−４４０（１９９２））のＦｉｇ．２で提案されていたカラーフィルタの分光特性を示す図である。
【図８１】特開平５−２４１１４３号公報の第２図（ａ）、（ｂ）、（ｃ）で提案されていたカラーフィルタの分光特性を示す図である。
【符号の説明】
１００１…上側偏光板、１００２…素子基板、１００３…液晶、１００４…対向基板、１００５…下側偏光板、１００６…散乱反射板、１００７…信号線、１００８…ＭＩＭ素子、１００９…画素電極、１０１０…カラーフィルタ、１０１１…対向電極（走査線）。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reflection type color liquid crystal device and an electronic apparatus using the same.
[0002]
[Prior art]
The display mounted on the portable information terminal needs to have low power consumption first of all. Therefore, a reflective liquid crystal device that does not require a backlight is optimal for this application. However, conventional reflection type liquid crystal devices mainly use monochrome display, and satisfactory reflection color display has not yet been obtained.
[0003]
It seems that the development of the reflective color liquid crystal device was started in earnest since the mid-1980s. Prior to that, there was only a recognition that if a backlight of a transmission type color liquid crystal device was replaced with a reflection plate, a reflection type color display would be possible, as disclosed in Japanese Patent Application Laid-Open No. 50-80799, for example. However, as you can see when you actually make it, such a configuration is dark and unusable. There are three causes. One is that more than 1/2 of the light is thrown away by the polarizing plate, the second is that more than 2/3 of the light is thrown away by the color filter, and finally the problem of parallax. It is. The problem of parallax is unavoidable in a TN (twisted nematic) mode and an STN (super twisted nematic) mode generally used in a transmission type liquid crystal device. This is because, in these modes, two polarizing plates are always used, so that a non-negligible gap occurs between the reflecting plate and the liquid crystal layer unless a polarizing plate is formed in the cell. The problem of parallax referred to here refers not only to the problem of double reflection of the display which is also present in the conventional reflective monochrome liquid crystal device, but also to a problem unique to the reflective color liquid crystal device.
[0004]
The problem of parallax will be described with reference to the drawings. FIGS. 77A and 77B are cross-sectional views of a reflection type color liquid crystal device using a TN mode or an STN mode. This liquid crystal device includes an upper polarizing plate 7701, an upper glass substrate 7702, a liquid crystal layer 7703, a lower glass substrate 7704, a lower polarizing plate 7705, a light reflecting plate 7706, and a red, green, and blue color filter 7707. A transparent electrode, an alignment film, an insulating film, and the like also exist between the upper and lower glass substrates, but they are not necessary for explaining the problem of parallax, and thus are omitted. There are two problems with parallax. One of them is the cancellation of colors. In FIG. 77 (a), an observer 7712 sees reflected light 7711 that has passed through a green filter, and this light is incident light 7713 passing through red, green, and blue filters. They are scattered and reflected by the reflector and mixed together. If the thickness of the lower glass substrate is sufficiently thicker than the pitch of the color filters, light that has passed through any color filter will be mixed with equal probability. However, light passing through the red → green and blue → green paths is absorbed by any one of the color filters and becomes completely dark, leaving only light passing through the green → green path. The same can be said for the reflected light coming out through the blue or red filter, so that there is a problem that the brightness of the white display is reduced to 1/3 of the case where there is no parallax. Another problem is that the color display becomes dark. FIG. 77 (b) shows a green display state. A hatched portion of the liquid crystal layer 7703 indicates a non-lighting state (dark state). The incident light 7713 passes through the red, green, and blue dots with equal probability, and two-thirds of the light is absorbed by the red and blue dots in the off state. Further, after being scattered and mixed by the light reflecting plate, 2/3 are absorbed again by the red and blue dots in the off state, and reach the observer 7712. Therefore, the green display is "1/9 of the brightness of the white display minus the absorption of the green filter", which is very dark. It is very difficult to use the TN mode or the STN mode having the parallax problem in the reflective color liquid crystal device.
[0005]
Therefore, conventionally, attempts have been made to obtain a bright reflective color display by changing the liquid crystal mode. For example, in a paper by Tatsuo Uchida et al. (IEEE Transactions on Electron Devices, Vol. ED-33, No. 8, pp. 1207-1121 (1986)), FIG. After comparing the brightness of various liquid crystal modes in 2, the PCGH (phase change type guest host) mode which does not require a polarizing plate is adopted. JP-A-5-241143 also employs a PDLC (polymer dispersed liquid crystal) mode that does not require a polarizing plate in order to realize a reflective color liquid crystal device. The use of a liquid crystal mode that does not require a polarizing plate not only eliminates light absorption by the polarizing plate, but also has the advantage that the problem of parallax can be fundamentally eliminated by providing a reflector adjacent to the liquid crystal layer. However, on the other hand, the liquid crystal mode which does not require a polarizing plate has a problem that the contrast is generally low, and particularly, the PCGH mode has a problem that the halftone display cannot be performed due to the hysteresis of the voltage transmittance characteristic. In addition, these liquid crystal modes in which another substance is added to the liquid crystal have many problems in terms of reliability. Therefore, if a TN mode or an STN mode, which has been widely used in the past and has been used, can be used, it will not be exceeded.
[0006]
Conventionally, attempts have been made to obtain a bright reflective color display using a bright color filter. Generally, a color filter used in a transmission type color liquid crystal device has a spectral characteristic as shown in FIG. In FIG. 78, the horizontal axis is the light wavelength, the vertical axis is the transmittance, 7801 is the spectrum of the red filter, 7802 is the spectrum of the green filter, and 7803 is the spectrum of the blue filter. Light that can be perceived by humans has a wavelength range of about 380 nm to 780 nm, though there is an individual difference, and particularly high visibility in a wavelength range of 450 nm to 660 nm. In the color filters shown in FIG. 78, there are wavelengths at which the transmittance is 10% or less in this range, and a lot of light is wasted. When a value obtained by simply averaging the transmittance in this wavelength range was defined as an average transmittance, the average transmittance of the red filter was 28%, the green filter was 33%, and the blue filter was 30%.
[0007]
Brighter color filters are needed for use in reflective color liquid crystal devices. Thus, in the above-mentioned paper by Tatsuo Uchida et al., FIG. It has been proposed to use two color filters having a complementary color relationship as shown in FIG. 8 to make the colors brighter than in the case of three colors. FIG. 79 shows the spectral characteristics. The horizontal axis of FIG. 79 is the wavelength of light, the vertical axis is the reflectance, 7901 is the spectrum of the green filter, and 7902 is the spectrum of the magenta filter. It is necessary to pay attention to the comparison because the vertical axis indicates the reflectance. However, there is also a wavelength in the wavelength range of 450 nm to 660 nm where the transmittance of all the color filters is 10% or less. The average transmittance was 41% for the green filter and 48% for the magenta filter.
[0008]
A paper by Seiichi Mitsui et al. (SID92 DIGEST, pp. 437-440 (1992)) also relates to a reflective color liquid crystal device employing the same PCGH mode. 2 is used. FIG. 80 shows the spectral characteristics. In FIG. 80, the horizontal axis is the wavelength of light, the vertical axis is the reflectance, 8001 is the spectrum of the green filter, and 8002 is the spectrum of the magenta filter. Although the vertical axis represents the reflectance, assuming that the square root of the reflectance at each wavelength is the transmittance, at least the transmittance of the green filter is less than 50% at a wavelength of 470 nm or less. The average transmittance was 68% for the green filter and 67% for the magenta filter. In this paper, there is no problem of parallax because the reflector is provided at a position adjacent to the liquid crystal layer with the color filter interposed therebetween. Therefore, since light always passes through the color filter twice, sufficient coloring can be ensured even with such a bright color filter.
[0009]
The color filters proposed in FIGS. 2 (a), (b) and (c) of Japanese Patent Application Laid-Open No. Hei 5-241143 are not three colors of red, green and blue, but yellow, cyan and blue. It is brightened using three colors of magenta. FIG. 81 shows the spectral characteristics. In FIG. 81, the horizontal axis is the light wavelength, the vertical axis is the reflectance, 8101 is the spectrum of the yellow filter, 8102 is the spectrum of the cyan filter, and 8103 is the spectrum of the magenta filter. It is difficult to make a comparison because the vertical axis represents the reflectance and the axis is not scaled. However, in the wavelength range of 450 nm to 660 nm, the transmittance of any color filter is 10% or less. There is no doubt that wavelengths exist. When roughly estimated, the average transmittance was about 0% for the yellow filter, about 60% for the cyan filter, and about 50% for the magenta filter.
[0010]
As described above, the conventional approach for developing a reflective color liquid crystal device was based on the idea of obtaining a bright display by combining a bright liquid crystal mode without using a polarizing plate and a bright color filter. However, a bright color filter often uses a color filter having a wavelength at which the transmittance is less than 10% in a wavelength range of 450 nm to 660 nm.
[0011]
[Problems to be solved by the invention]
An object of the present invention is to provide a reflective color liquid crystal device capable of displaying bright and vivid colors, and to provide an electronic apparatus using the same.
[0012]
[Means for Solving the Problems]
According to a first aspect of the present invention, in the reflection type color liquid crystal device having a pair of substrates disposed opposite to each other and including a plurality of color filters, the plurality of color filters include a red color filter and a blue color filter. A color filter and a green color filter are included. The red color filter is for light in a wavelength range of 570 nm to 660 nm, and the blue color filter is for light in a wavelength range of 450 nm to 520 nm. Each of the green color filters has a transmittance of 70% or more for light in a wavelength range of 510 nm to 590 nm.
[0013]
According to a second aspect of the present invention, there is provided an electronic apparatus including the reflective color liquid crystal device according to the first aspect as a display unit.
[0014]
According to a third aspect of the present invention, in the electronic device according to the second aspect, the display unit of the reflective color liquid crystal device is attached to be movable with respect to the main body so that ambient light can be efficiently reflected to an observer. It is characterized by having.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
An outline of the present invention will be described. The present invention is directed to a pair of substrates having electrodes formed on opposing inner surfaces and forming a matrix of dot groups, a liquid crystal sandwiched between the substrates, at least two color filters, and at least one polarizing plate, A configuration having a reflection plate can be employed. As the liquid crystal mode, a liquid crystal mode using a polarizing plate such as a TN mode or an STN mode can be used.
[0016]
Further, the thickness of the substrate located on the reflection plate side of the pair of substrates may be 200 μm or more. More preferably, the thickness of the substrate located on the reflection plate side can be set to 700 μm or more. In other words, the thickness of the substrate located on the reflection plate side can be 1.25 times or more of the shorter of the dot pitch in any of the vertical and horizontal directions, and more preferably 4 times or more. With such a configuration, there is an advantage that high contrast can be secured by the effect of parallax even if the driving area ratio is small.
[0017]
Conventionally, for example, Japanese Patent Publication No. 3-64850 proposes that the thickness of a lower substrate of a reflection type monochrome liquid crystal device be 300 μm or less. Certainly, in the reflection type monochrome display, the lower substrate should be as thin as possible from the viewpoint of reducing double images (shadow). However, in the case of the reflective color display, it is desired to increase the space between dots from the viewpoint of brightening the color display. If the space between the dots is wide, the contrast is inevitably reduced. However, if the lower substrate is sufficiently thick, a high contrast can be secured by the shadow effect of the adjacent pixels.
[0018]
In addition, among the color filters, at least one color filter may have a transmittance of 50% or more for light of all wavelengths in a range of 450 nm to 660 nm. More preferably, at least two color filters can have a transmittance of 50% or more for light of all wavelengths in the range of 450 nm to 660 nm. More preferably, any of the color filters can have a transmittance of 50% or more for light of all wavelengths in the range of 450 nm to 660 nm. Most preferably, any color filter can have a transmittance of 60% or more for light of all wavelengths in the range of 450 nm to 660 nm. In other words, any of the color filters can have an average transmittance of 70% or more with respect to light having a wavelength in the range of 450 nm to 660 nm. More preferably, any of the color filters can have an average transmittance of 75% or more and 90% or less for light having a wavelength in the range of 450 nm to 660 nm.
[0019]
Here, the transmittance of the color filter referred to here is the transmittance of the color filter alone, not including the transmittance of the glass substrate, the transparent electrode, the overcoat, and the undercoat. When the density of the color filter has a distribution, or when the color filter is provided only in a part of the dot, the average transmittance in the dot is set as the transmittance of the color filter. With this configuration, the reflective color liquid crystal device has an advantage that a bright color can be displayed. Conventionally, for example, in the claims of Japanese Patent Application Laid-Open No. 7-239469, the transmittance of each color filter is set to 80% or more in the light transmission region and the transmittance in the light absorption region is set to 50% or less. Also, in the embodiment, the transmittance of the light absorption region is only 20 to 30%. In such a color filter, if a liquid crystal mode using a polarizing plate is used, the display becomes dark, which is not practical.
[0020]
Further, the color filter may be composed of three colors of red, green and blue, and one of the red or blue color filters may be orange or cyan. However, the orange filter can have a transmittance of at least 70%, preferably at least 75%, for light in the wavelength range of 570 nm to 660 nm. Further, the cyan filter is characterized in that it has a transmittance of at least 70%, preferably at least 75% for light in the wavelength range of 450 nm to 520 nm. With such a configuration, the reflective color liquid crystal device has an advantage that bright white and bright colors can be displayed.
[0021]
Further, the color filter is composed of three colors of red, green and blue, and the minimum transmittance of the red color filter for light having a wavelength in the range of 450 nm to 660 nm is blue or green color. It is characterized in that it is smaller than the minimum transmittance of the color filter of the filter for light having a wavelength in the range of 450 nm to 660 nm. More preferably, the blue and green color filters have a transmittance of 50% or more for light of all wavelengths in the range of 450 nm to 660 nm. More preferably, the blue color filter is cyan. With such a configuration, the reflective color liquid crystal device has an advantage that it can display bright white with little coloring and also can display vivid red. Since red is the color stimulus that most appeals to the human eye, it is highly preferable to display red with emphasis.
[0022]
Further, the color filter is provided only in a part of the light modulatable area in each dot. With this configuration, the reflection type color liquid crystal device of the present invention has an advantage that color mixing due to parallax can be reduced while the conventional color filter manufacturing technology can be used. In particular, when a color filter is provided at a position between the electrode and the liquid crystal, there is an advantage that a wide viewing angle is obtained and color purity in a halftone is improved. Conventionally, for example, Japanese Patent Publication No. 7-62723 proposes providing a color filter on a part of a dot. However, this is a transmission type liquid crystal device and is limited to a color filter for a dyeing method. The present invention differs from the present invention in that the area where the filter is provided is as large as 67% to 91% of the dot. (The expression in Japanese Patent Publication No. 7-62723 states that “the area of the non-colored portion is 10 to 50% of the area of the colored portion.” Therefore, the area of the colored portion to be formed into dots is 100/150 = 67% to 100%.) / 110 = 91%.)
[0023]
Further, a transparent layer in the visible light region is formed to have a thickness substantially equal to that of the color filter in a region where a color filter is not provided in the region where light modulation is possible and in a region where light modulation is not possible. With such a configuration, the reflective color liquid crystal device has an advantage that high-quality display can be performed without disturbance of liquid crystal alignment.
[0024]
Further, the color filter is provided only for dots having a number equal to or less than 3/4 of the total number of dots. More preferably, it is characterized in that the dots are provided only for two-thirds or less of the total number of dots. With this configuration, a bright display is possible, and also in the case of displaying a halftone color, if the brightness is adjusted mainly with dots without a color filter, there is an advantage that a vivid color can always be displayed. is there. Conventionally, in a transmissive liquid crystal device, one pixel is formed by four dots of red, green, blue, and white, but it has never been proposed in a reflective liquid crystal device. In particular, in a reflective type color liquid crystal device using a TN mode or an STN mode, a problem of parallax is inevitable, and when a color display is performed, it becomes very dark. However, by providing a dot without a color filter, a bright color display can be achieved. It is possible.
[0025]
Further, the color filters may be arranged so that adjacent dots have different colors. This indicates a so-called mosaic arrangement or triangle arrangement, and conversely, a stripe arrangement does not fall within this range. With such a configuration, there is an advantage that the phenomenon that the degree of coloring varies depending on the viewing angle is reduced, particularly when there is parallax. Conventionally, for example, Japanese Patent Application Laid-Open No. 8-87009 proposes a vertical stripe arrangement in claim 6 thereof. Also, Japanese Patent Application Laid-Open No. 5-241143 states that there is no fundamental difference between the stripe arrangement and the staggered arrangement in the right column, line 17 to line 18, page 6 of the specification. In addition, a paper by Tatsuo Uchida et al. (IEEE Transactions on Electron Devices, Vol. ED-33, No. 8, pp. 1207-1121 (1986)). In No. 1, a mosaic-arranged color filter is employed. However, this is a case where a reflective electrode is provided in a cell, which is different from the present invention because there is no parallax.
[0026]
Further, the color filter may be provided over the entire effective display area. This configuration has the advantage that the display looks bright. The “effective display area” is defined as a “drive display area and a subsequent area effective as a screen” in ED-2511A of the Japan Electronic Machinery Manufacturers Association (EIAJ) standard. Normally, in a transmissive color display, a color filter is provided only in a driving display area, and a black mask made of metal or resin is provided in an area outside the driving display area. However, in a reflective type color display, a metal black mask cannot be used because it is glaring. Further, the cost of the resin black mask is increased because the original color filter is not provided with the black mask. However, if nothing is provided outside the driving display area, the outside becomes bright and the driving display area looks relatively dark. Therefore, it is effective to provide a color filter similar to that inside the driving display area, preferably in the same pattern.
[0027]
Further, a black mask may not be provided in an area outside each dot, and a color filter having absorption equal to or smaller than the area in the dot may be provided instead. This configuration means that no black mask or color filter overlap is provided outside the dots. Further, it means that a color filter is provided in a part or the whole, instead of providing nothing outside the dot. This configuration has an advantage that a bright display can be obtained. This is because, particularly when there is parallax, since the brightness of the display is substantially proportional to the square of the aperture ratio, it becomes very dark when a black mask is provided. Conversely, if no color filters are provided outside the dots This is because the contrast is significantly reduced. Conventionally, for example, in JP-A-59-198489, a color filter is provided only on a pixel electrode, and nothing is provided outside the color filter. Japanese Patent Application Laid-Open No. 5-241143 describes both the case with and without the black mask, but there is no middle point between them.
[0028]
Further, a color filter may be provided on an outer surface of the pair of substrates located on the side of the reflection plate. This configuration has the advantage that it can be provided at low cost. Further, by combining this configuration with a configuration in which the color filter is provided only in a part of the light modulatable area in each dot, there is an advantage that an assembly margin is increased and a viewing angle is widened.
[0029]
In addition, a non-linear element may be provided corresponding to each dot on an inner surface of the substrate located on the reflection plate side of the pair of substrates. With this configuration, there is an advantage that unnecessary surface reflection is reduced and high contrast is obtained.
[0030]
Further, a non-linear element may be provided for each dot on the inner surface of one of the pair of substrates and connected in a direction parallel to the short side of the dot. Usually, especially in a data display for a PC, dots are often vertically long, and the direction parallel to the short sides of the dots is the horizontal direction (horizontal direction). With such a configuration, there is an advantage that the aperture ratio is increased and a bright display is obtained. This is particularly effective when a black mask is not provided, or when a reflective configuration having parallax is used.
[0031]
Further, the driving area ratio can be set to be 60% or more and 85% or less. Here, the driving area ratio is defined as a ratio of a region where liquid crystal is driven in a region excluding an opaque portion such as a metal wiring or an MIM element in a pixel. With this configuration, there is an advantage that a bright color display can be obtained while ensuring the contrast.
[0032]
The reflector may have a scattering characteristic such that when a light beam enters the reflector, 80% or more of the light is reflected in a 30-degree cone centered on the specular reflection direction. it can. Preferably, it is possible to have a scattering characteristic such that 95% or more of the light is reflected in a 30-degree cone. This configuration has an advantage that a bright display can be obtained. Conventionally, for example, in Japanese Patent Application Laid-Open No. 8-87009, a reflecting plate having a directivity with a half width of 30 degrees is used on page 6, right column, lines 43 to 44 of the specification. When the half width is 30 degrees, the scattering characteristic is such that approximately 30% of the light is reflected in a 30-degree cone, roughly calculated, and the scattering is too large as compared with the present invention. With such characteristics, the display becomes dark and is not practical.
[0033]
Further, the reflection plate may be a transflective reflection plate, and a backlight may be provided on a back surface thereof. Preferably, the reflector reflects at least 80% of the incident light. With such a configuration, there is an advantage that the image can be seen even in a dark environment.
[0034]
Further, the liquid crystal may be a nematic liquid crystal twisted by approximately 90 degrees, and two polarizing plates may be arranged such that their transmission axes are respectively orthogonal to the rubbing directions of the adjacent substrates. This is an application of the TN mode proposed in JP-B-51-113666 to a reflection type color liquid crystal device. With this configuration, the reflective color liquid crystal device has advantages of being bright, having high contrast, and having a wide viewing angle.
[0035]
The product Δn × d of the birefringence Δn of the liquid crystal and the thickness d of the liquid crystal layer can be set to be larger than 0.34 μm and smaller than 0.52 μm. More preferably, Δn × d can be set to 0.40 μm or more and 0.52 μm or less. Most preferably, Δn × d can be 0.42 μm. With this configuration, the reflection type color liquid crystal device has advantages of being bright and having a wide viewing angle.
[0036]
In a conventional reflection type monochrome liquid crystal device, a second minimum condition with little coloring, that is, a condition where Δn × d is about 1.1 μm to 1.3 μm, has been used. However, in the reflection type color liquid crystal device, it is not necessary to adopt the second minimum condition since a little coloring can be compensated by the color filter. Further, in Japanese Patent Application Laid-Open No. Hei 8-87009, the condition of Δn × d = 0.55 μm is adopted as shown in the specification, page 5, lines 27 to 29. However, under this condition, the color is dark and the coloring is large as compared with the condition where Δn × d is larger than 0.34 μm and smaller than 0.52 μm.
[0037]
Further, the liquid crystal may be a nematic liquid crystal twisted by 90 degrees or more, and may have a configuration in which two polarizing plates and at least one retardation film are arranged. If possible, it is desirable to perform multi-line simultaneous selection drive according to the method disclosed in Japanese Patent Application Laid-Open No. 6-348230. With such a configuration, there are advantages of low cost and brightness.
[0038]
Further, a configuration may be employed in which the reflection plate is provided between a pair of substrates, and only one polarizing plate is disposed. This is an application of a single-polarizer type nematic liquid crystal mode proposed in Japanese Patent Application Laid-Open No. 3-223715 to a reflection type color liquid crystal device. With this configuration, there is an advantage that a bright color with high color purity can be displayed.
[0039]
Further, the reflection plate may be a mirror reflection plate, and a scattering plate may be provided on an outer surface of the substrate located on the incident light side. With this configuration, there is an advantage that a bright color with high color purity can be displayed.
[0040]
In addition, a configuration in which the liquid crystal on the metal wiring is oriented similarly to the liquid crystal in the pixel portion can be employed. This configuration has the advantage of being bright.
[0041]
Further, the display can be a normally white type. This configuration has the advantage of being bright.
[0042]
Further, one dot can constitute one pixel. This configuration has the advantage that the resolution can be increased during monochrome display.
[0043]
Further, the electronic device of the present invention can be configured to include a reflective color liquid crystal device as a display unit. With this configuration, the electronic device has advantages of low power consumption, thinness and light weight, and good visibility even in direct sunlight.
[0044]
In addition, the display unit can be configured to be movable with respect to the main body so that ambient light can be efficiently reflected to the observer. With such a configuration, there is an advantage that a bright display can be obtained under any lighting conditions.
[0045]
As can be understood from the above description, the present invention is characterized by utilizing a liquid crystal mode using a polarizing plate and combining this with a bright color filter. Although there are many liquid crystal display modes using a polarizing plate, the purpose of the present invention is to provide a liquid crystal display mode capable of bright and black-and-white display, for example, a TN mode proposed in Japanese Patent Publication No. 51-113666, and Japanese Patent Publication No. 3-50249. STN mode proposed in Japanese Patent Application Laid-Open Publication No. Hei 3-223715, a nematic liquid crystal mode proposed in Japanese Patent Laid-Open No. Hei 3-223715, and bistable proposed in Japanese Patent Application Laid-Open No. Hei 6-235920. A nematic liquid crystal mode in which switching is performed is suitable.
[0046]
In the liquid crystal mode using a polarizing plate, 1/2 or more of the light is discarded only by the presence of the polarizing plate. Therefore, a liquid crystal mode using no polarizing plate should be more suitable for a reflective color liquid crystal device. However, the liquid crystal mode using no polarizing plate generally has low contrast in both the PCGH mode and the PDLC mode. Therefore, for example, when a pixel is composed of three red, green, and blue dots, the contrast is insufficient even if the green dot is set to a bright state and the blue and red pixels are set to a dark state for displaying green. Then, blue and red are mixed in the green display, and the color purity is reduced. However, in a liquid crystal mode using a polarizing plate, such a phenomenon does not occur because the contrast is high. Therefore, if the same color is displayed, a liquid crystal mode using a polarizing plate can use a color filter with lower color purity. A color filter with low color purity is a bright color filter, so that a bright display should be made accordingly. In particular, since PCGH is a normally black display, the area between dots becomes black and does not contribute to brightness, and light from a viewing angle direction other than the panel normal direction is absorbed by a dye. In spite of not using a plate, the brightness is only about 20% higher than that of the TN mode. Such a difference in brightness can easily be overcome depending on the color design of the color filter.
[0047]
Another problem in using a liquid crystal mode using a polarizing plate is the existence of parallax. When only one polarizing plate is used, this problem can be avoided by forming a reflecting plate in the cell, but it cannot be avoided in the TN mode or the STN mode using two polarizing plates. Although the parallax has been described in detail in the section of “Prior Art”, there are two problems. One is the cancellation of colors, and the other is the darkening of the color display.
[0048]
The problem of color cancellation is that if the color filters that pass through at the time of incidence and the color filters that pass through at the time of emission differ, they cancel each other out and become completely dark, so that the brightness of the white display does not have parallax. That is, it becomes 1/3. Such a problem arises because the color filter used in the transmission type as shown in FIG. 78 is used as it is. If a bright color filter is used, it will not be completely dark even if it passes through a color filter of a different color.
[0049]
In addition, the problem of color display being dark is that, when displaying a single color, two-thirds of the entire dots are in a dark state, so that two-thirds of light is absorbed at the time of incidence and is further two-thirds at the time of emission. Is absorbed, and only 1/9 of the light is available. This is 1/3 of the brightness when there is no parallax. To solve this, it is necessary to first increase the aperture ratio. Specifically, measures were taken such as not providing a black mask outside the dots, using an MIM in which the metal wiring is only in one direction, wiring the MIM in the horizontal direction, or using an STN that does not require a metal wiring. Then, by further reducing the driving area ratio, an area much smaller than 全体 of the entire area (for example, about）) becomes a dark state when displaying a single color. In this way, a bright color display is possible even if there is parallax. Means such as reducing the driving area ratio or not providing a black mask leads to a decrease in contrast. However, by decreasing the thickness of the lower substrate, it is possible to minimize the decrease in contrast.
[0050]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0051]
(Example 1)
FIG. 1 is a diagram showing a main part of the structure of a reflective type color liquid crystal device according to a first embodiment of the present invention, in which a pair of substrates having electrodes formed on opposing inner surfaces to form a matrix of dot groups, , A liquid crystal, a color filter of at least two colors, at least one polarizing plate, and a reflector. In the figure, 101 is an upper polarizer, 102 is a counter substrate, 103 is a liquid crystal, 104 is an element substrate, 105 is a lower polarizer, and 106 is a scattering reflector. An electrode (scanning line) 108 was provided, and a signal line 109, a pixel electrode 110, and an MIM element 111 were provided on the element substrate 104. Here, 101 and 102, 104 and 105, and 105 and 106 are drawn apart, but this is for the sake of clarity of the drawing, and they are actually glued together. Further, the space between the opposing substrate 102 and the element substrate 104 is drawn widely apart, but for the same reason, there is only a gap of about several μm to about several tens μm in practice. Although FIG. 1 shows the main part of the reflection type color liquid crystal device, only 9 dots of 3 × 3 are shown. However, in this embodiment, the number of dots is larger than that of 480 × 640. It may have 307200 dots or more.
[0052]
The counter electrode 108 and the pixel electrode 110 were formed of transparent ITO, and the signal line 109 was formed of metal Ta. The MIM element is an insulating film Ta ₂ O ₅ Is sandwiched between metal Ta and metal Cr. The liquid crystal 103 is a nematic liquid crystal twisted by 90 degrees, and the polarizing axes of the upper and lower polarizing plates are orthogonal to each other. This is a general TN mode configuration. The color filters 107 are composed of two colors of red (indicated by “R” in the figure) and cyan (indicated by “C” in the figure), which are complementary to each other, and are arranged in a stripe pattern.
[0053]
FIG. 2 is a diagram illustrating the spectral characteristics of the color filter 107. In FIG. 2, the horizontal axis represents the wavelength of light and the vertical axis represents the transmittance. 201 indicates the spectrum of the red filter, and 202 indicates the spectrum of the cyan filter. The spectra were measured on the counter substrate alone using a microspectrophotometer and corrected for 100% transmittance, including the glass substrate, the transparent electrode and, if present, the overcoat and undercoat. Therefore, the spectral characteristics of the color filter alone are measured. Hereinafter, all the spectral characteristics of the color filters were measured by this method. The transmittance in the present invention is also defined as a value measured by this method. Both the red filter and the cyan filter always show a transmittance of 30% or more in the wavelength range of 450 nm to 660 nm. The average transmittance in the same wavelength range was 52% for the red filter and 66% for the cyan filter. Since such a color filter has a very light color tone, it is normally more accurate to write "pink" instead of "red". However, in order to avoid confusion, the expression will be unified with pure color below.
[0054]
The reflective color liquid crystal device prepared as described above has a reflectance of 24% in white display, a contrast ratio of 1:15, and can display four colors of white, red, cyan, and black. x = 0.39, y = 0.32, and the cyan display color was x = 0.28, y = 0.31. This is about 60% of the brightness of a conventional reflection type monochrome liquid crystal device, and has the same contrast ratio, and is a characteristic that can be sufficiently used under ordinary indoor illumination light or outdoors in the daytime.
[0055]
A reflective color liquid crystal device using a color filter that exhibits a transmittance of less than 30% at least in the wavelength range of 450 nm to 660 nm has a dark display and requires special illumination, or has an improper white balance. It cannot be used in normal use for any reason that white cannot be displayed.
[0056]
In the first embodiment, the structure in which the transparent electrode is provided on the color filter is employed. However, there is no particular problem even if the color filter is provided on the transparent electrode. Although the MIM element is used as the active element, this is advantageous in increasing the aperture ratio. Therefore, if the aperture ratio is the same, use of a TFT element does not change the effect of the present invention.
[0057]
(Example 2)
FIG. 3 is a diagram illustrating the spectral characteristics of the color filters of the reflective color liquid crystal device according to the second embodiment of the present invention. The configuration of the second embodiment is the same as that of the first embodiment shown in FIG. 1, and also includes a color filter including two colors of red and cyan. In FIG. 3, the horizontal axis represents the light wavelength, and the vertical axis represents the transmittance. Reference numeral 301 denotes the spectrum of the red filter, and 302 denotes the spectrum of the cyan filter. Each color filter has a transmittance of 50% or more in a wavelength range of 450 nm to 660 nm. The average transmittance in the same wavelength range was 71% for the red filter and 78% for the cyan filter.
[0058]
This reflective color liquid crystal device has a reflectivity of 30% for white display, a contrast ratio of 1:15, and can display four colors of white, red, cyan, and black. The red display color is x = 0.34. y = 0.32, the cyan display color was x = 0.29, and y = 0.31. This is a brightness of more than 70% of the conventional reflection type monochrome liquid crystal device and an equivalent contrast ratio.
[0059]
As described above, when at least one color filter has a transmittance of 50% or more for light of all wavelengths in the range of 450 nm to 660 nm, it can be used in an environment substantially equivalent to that of a conventional reflective monochrome liquid crystal device. Thus, a bright reflective color liquid crystal device can be obtained. In the case where the color filter is composed of two colors as in this embodiment, if one of the color filters has a transmittance of 50% or more for light of all wavelengths in the range of 450 nm to 660 nm, a good white color is obtained. In order to obtain a balance, the other color filter necessarily has a transmittance of 50% or more. However, this is not always the case when three or more color filters are used. An example is described later in Example 9.
[0060]
(Example 3)
FIG. 1 is a diagram showing a main part of the structure of a reflective color liquid crystal device according to a third embodiment of the present invention. FIG. 2 is a diagram showing the spectral characteristics of the color filters. In this embodiment, of the pair of substrates, the thickness of the substrate located on the reflection plate side was set to 200 μm or more. The configuration of the third embodiment is basically the same as that of the reflective color liquid crystal device described in the first embodiment, and the description of each reference numeral is omitted. However, Δn × d of the liquid crystal 103 was set to 0.42 μm. The dot pitch was 160 μm both vertically and horizontally, and the driving area ratio was 75%.
[0061]
In Example 3, the thickness of the lower substrate was changed variously. FIG. 4 shows the contrast when the thickness of the element substrate 104 is changed. In FIG. 4, the horizontal axis is the thickness of the element substrate 104, the vertical axis is the contrast, 401 is a group of points indicating the contrast with respect to the thickness of each element substrate 104 in Example 3, and 402 is the thickness of each element substrate 104 in the comparative example. It is a group of points indicating the contrast with respect to the distance. The display colors in color display were x = 0.39 and y = 0.32 in red display, and x = 0.28 and y = 0.31 in cyan display.
[0062]
Since the driving area ratio is 75%, when the thickness of the element substrate is zero, the contrast is only 100 / (100−75) = 4 at the maximum. However, by setting the thickness of the element substrate 104 to 200 μm or more, a good contrast of 1:15 or more was obtained by the effect of parallax, that is, the shadow of adjacent dots mitigated light leakage between the dots. Further, by setting the thickness of the element substrate to 700 μm or more, higher contrast could be obtained.
[0063]
Since the optimum value of the thickness is closely related to the dot pitch, the expressions “200 μm or more” and “700 μm or more” are replaced by “1.25 times or more of the shorter of the vertical or horizontal dot pitch” or “ Similarly, four times or more may be used.
[0064]
(Example 4)
FIG. 5 is a diagram illustrating the spectral characteristics of the color filters of the reflective color liquid crystal device according to the fourth embodiment of the present invention. The configuration of the third embodiment is the same as that of the first embodiment shown in FIG. 1, and also includes a color filter composed of two colors of red and cyan. In FIG. 5, the horizontal axis represents the wavelength of light, the vertical axis represents the transmittance, 501 represents the spectrum of the red filter, and 502 represents the spectrum of the cyan filter. Each color filter has a transmittance of 60% or more in a wavelength range of 450 nm to 660 nm. The average transmittance in the same wavelength range was 75% for the red filter and 80% for the cyan filter.
[0065]
This reflective color liquid crystal device has a reflectance of 31% in white display, a contrast ratio of 1:15, and can display four colors of white, red, cyan and black, and a red display color is x = 0.33. y = 0.33, the cyan display color was x = 0.30, and y = 0.31. This is about 80% of the brightness of the conventional reflection type monochrome liquid crystal device, and the same contrast ratio.
[0066]
As described above, if any color filter has a transmittance of 60% or more for light of all wavelengths in the range of 450 nm to 660 nm, input means such as touch keys can be provided on the entire surface of the liquid crystal device. A bright reflective color liquid crystal device that can be used without any problem even when attached is obtained. However, if a color filter having an average transmittance exceeding 90% in the same wavelength range is used, the display color becomes extremely faint and it becomes difficult to identify the color.
[0067]
(Example 5)
FIG. 6 is a diagram showing a main part of the structure of a reflective color liquid crystal device according to a fifth embodiment of the present invention. In this embodiment, the color filters are arranged such that adjacent dots have different colors. First, the configuration will be described. 601 is an upper polarizing plate, 602 is a counter substrate, 603 is a liquid crystal, 604 is an element substrate, 605 is a lower polarizing plate, 606 is a scattering reflector, and a color filter 607 and a counter electrode (scanning) are provided on the counter substrate 602. Line) 608, and a signal line 609, a pixel electrode 610, and an MIM element 611 were provided on the element substrate 604.
[0068]
Here, the color filter 7 is composed of two colors of red (indicated by “R” in the figure) and cyan (indicated by “C” in the figure) which are complementary to each other, and draws a checkerboard pattern in a mosaic form. It was arranged as follows. When the color filters are arranged in a stripe pattern as shown in FIG. 1, the viewing angle characteristics are extremely wide in the vertical direction, but when the viewing angle is changed in the left-right direction, the viewing angle direction in which the color is colored and the viewing angle direction in which the color is erased appear alternately. This is a phenomenon that occurs because there is a distance between the liquid crystal layer and the color filter layer and the reflection plate by the thickness of the lower substrate (in this case, the element substrate). Experiments have confirmed that such a phenomenon can be considerably reduced by arranging a checkerboard pattern in a mosaic pattern as shown in FIG. In particular, it was also found that color mixing was good even when the number of pixels was relatively small. This is considered to be because, in the case of the mosaic arrangement, the viewing angle direction in which the coloring is performed and the viewing angle direction in which the color is erased are mixed, so that at least one of the eyes looks colored. The color filter had the same spectral characteristics as FIG. 3 of the second embodiment, and the brightness and the contrast ratio were almost the same as those of the second embodiment. Although the example of the mosaic arrangement has been described here, other arrangements such as a triangle arrangement are also effective as long as adjacent dots have different colors.
[0069]
(Example 6)
FIG. 7 is a diagram illustrating the spectral characteristics of the color filters of the reflective color liquid crystal device according to the sixth embodiment of the present invention. The configuration of the second embodiment is the same as that of the fifth embodiment shown in FIG. 6, but includes a color filter composed of two colors of green and magenta instead of red and cyan. In FIG. 7, the horizontal axis is the wavelength of light and the vertical axis is the transmittance, 701 indicates the spectrum of the green filter, and 702 indicates the spectrum of the magenta filter. Each color filter has a transmittance of 50% or more in a wavelength range of 450 nm to 660 nm. The average transmittance in the same wavelength range was 76% for the green filter and 78% for the magenta filter.
[0070]
This reflective color liquid crystal device has a reflectance of 31% in white display, a contrast ratio of 1:17, and can display four colors of white, green, magenta, and black, and a green display color is x = 0.31. y = 0.35, the magenta display color was x = 0.32, and y = 0.29. This is about 80% of the brightness of the conventional reflection type monochrome liquid crystal device, and the same contrast ratio.
[0071]
As the two complementary colors, a combination of red and cyan, green and magenta, and a combination of blue and yellow can also be considered. It is more preferred in that it does.
[0072]
(Example 7)
FIG. 8 is a diagram showing a main part of the structure of a reflective color liquid crystal device according to a seventh embodiment of the present invention. First, the configuration will be described. Reference numeral 801 denotes an upper polarizer, 802 denotes a counter substrate, 803 denotes a liquid crystal, 804 denotes an element substrate, 805 denotes a lower polarizer, and 806 denotes a scattering reflector. A color filter 807 and a counter electrode (scanning) are provided on the counter substrate 802. Line 808, and a signal line 809, a pixel electrode 810, and an MIM element 811 were provided on the element substrate 804. On the upper polarizing plate, a weak anti-glare treatment was applied in order to suppress glare of the illumination light.
[0073]
Here, the color filter 807 is composed of three colors, red (indicated by “R” in the figure), green (indicated by “G” in the figure), and blue (indicated by “B” in the figure). And arranged in a mosaic pattern as shown.
[0074]
FIG. 9 is a diagram illustrating the spectral characteristics of the color filter 807. In FIG. 9, the horizontal axis is the wavelength of light and the vertical axis is the transmittance, 901 indicates the spectrum of the red filter, 902 indicates the spectrum of the green filter, and 903 indicates the spectrum of the blue filter. Each color filter has a transmittance of 50% or more in a wavelength range of 450 nm to 660 nm. The average transmittance in the same wavelength range was 74% for the red filter, 75% for the green filter, and 63% for the blue filter.
[0075]
The reflection type color liquid crystal device prepared as described above has a reflectance of 28% in white display, a contrast ratio of 1:14, is capable of full color display, and has a red display color of x = 0.39 and y = 0. .32, the green display color was x = 0.31, y = 0.35, and the blue display color was x = 0.29, y = 0.27. This is about 70% of the brightness of the conventional reflection type monochrome liquid crystal device, and has the same contrast ratio, and is a characteristic that allows video images to be enjoyed without requiring special illumination.
[0076]
(Example 8)
FIG. 10 is a diagram showing a main part of the structure of a reflective color liquid crystal device according to Embodiment 8 of the present invention. In this embodiment, among the color filters, at least one color filter has a transmittance of 50% or more for light of all wavelengths in the range of 450 nm to 660 nm. The color filters are of three colors, red, green and blue, and one of the red or blue color filters is orange or cyan. First, the configuration will be described. 1001 is an upper polarizing plate, 1002 is an element substrate, 1003 is a liquid crystal, 1004 is a counter substrate, 1005 is a lower polarizing plate, 1006 is a scattering reflector, and a counter electrode (scanning line) 1011 and a color are provided on the counter substrate 1004. A filter 1010 was provided, and a signal line 1007, a MIM element 1008, and a pixel electrode 1009 were provided over an element substrate 1002. The color filter 1010 is a pigment-dispersed type, and has three colors of red (indicated by “R” in the figure), green (indicated by “G” in the figure), and blue (indicated by “B” in the figure). Made up of
[0077]
FIG. 11 is a diagram illustrating the spectral characteristics of the color filter 1010. In FIG. 11, the horizontal axis is the light wavelength, and the vertical axis is the transmittance. 1101 is the spectrum of the red filter, 1102 is the spectrum of the green filter, and 1103 is the spectrum of the blue filter. 1101, 1102, and 1103 are light color filters, but the images displayed by such color filters are pale. In particular, red and blue have low visibility, so that it is difficult to distinguish the colors. Therefore, a bright color filter that transmits light in a wider wavelength range even when the color is slightly changed was used.
[0078]
When a red filter with low color purity was used in place of the red filter, a very bright red with a slightly orange color could be displayed. The spectrum of this filter is shown at 1111. This filter is characterized by having a transmittance of at least 70%, preferably at least 75%, for light in the wavelength range of 570 nm to 660 nm. When a blue filter having low color purity was used in place of the blue filter, a very bright blue with a slightly cyan color could be displayed. The spectrum of this filter is shown at 1113. This filter is characterized by having a transmittance of at least 70%, preferably at least 75%, for light in the wavelength range of 450 nm to 520 nm. However, when such a color filter is used, the white display tends to be bluish or reddish. Therefore, when using the above color filter, it is desirable to adjust the color balance in combination with a green filter having higher color purity. An example of a green filter with high color purity is shown at 1112. This filter is characterized by having a transmittance of 70% or more only for light in the wavelength range of 510 nm to 590 nm.
[0079]
(Example 9)
FIG. 12 is a diagram illustrating the spectral characteristics of the color filters of the reflective color liquid crystal device according to the ninth embodiment of the present invention. The configuration of the ninth embodiment is the same as that of the seventh embodiment shown in FIG. 8, and also includes a color filter composed of three colors of red, green and blue. In FIG. 12, the horizontal axis represents the light wavelength, and the vertical axis represents the transmittance. Reference numeral 1201 denotes a red filter spectrum, 1202 denotes a green filter spectrum, and 1203 denotes a blue filter spectrum. The minimum transmittance of the red color filter for light having a wavelength in the range of 450 nm to 660 nm is smaller than the minimum transmittance of the blue and green color filters for light having a wavelength in the range of 450 nm to 660 nm. Here, only the green filter has a transmittance of 50% or more in the wavelength range of 450 nm to 660 nm. The minimum transmittance of the red filter for light having a wavelength in the range of 450 nm to 660 nm is distinctly smaller than that of the blue filter and the green filter. By using such a red filter, it is possible to vividly display red that appeals to human eyes. To compensate for the darkening of red, the spectrum 1203 of the blue filter was set close to cyan. For this reason, bright white with little coloring could be displayed.
[0080]
The reflective color liquid crystal device prepared as described above has a reflectivity of 26% in white display, a contrast ratio of 1:13, and is capable of full-color display. The red display color is x = 0.41 and y = 0. .30, green display color was x = 0.31, y = 0.36, and blue display color was x = 0.26, y = 0.28. This is about 70% of the brightness of the conventional reflective monochrome liquid crystal device, and the same contrast ratio. Since the red color is particularly emphasized, the color reproducibility is not sufficient. Therefore, it is more suitable for displaying on a portable information device or the like than displaying video images.
[0081]
(Example 10)
FIG. 10 is a diagram showing a main part of the structure of a reflective color liquid crystal device according to Embodiment 10 of the present invention. The configuration will be described. 1001 is an upper polarizing plate, 1002 is an element substrate, 1003 is a liquid crystal, 1004 is a counter substrate, 1005 is a lower polarizing plate, 1006 is a scattering reflector, and a counter electrode (scanning line) 1011 and a color are provided on the counter substrate 1004. A filter 1010 was provided, and a signal line 1007, a MIM element 1008, and a pixel electrode 1009 were provided over an element substrate 1002. The color filter 1010 is a pigment-dispersed type, and has three colors of red (indicated by “R” in the figure), green (indicated by “G” in the figure), and blue (indicated by “B” in the figure). Made up of
[0082]
FIG. 13 is a diagram illustrating the spectral characteristics of the color filter 1010. In FIG. 13, the horizontal axis is the light wavelength, and the vertical axis is the transmittance. 1301 and 1311 show the spectrum of the red filter, 1302 and 1312 show the spectrum of the green filter, and 1303 and 1313 show the spectrum of the blue filter. The color filter materials 1301 and 1311, 1302 and I312, 1303 and 1313 are the same, but have different thicknesses, and the former is 0.8 μm and the latter is 0.2 μm. The average transmittance of the red filter for light in the wavelength range of 450 nm to 660 nm was 28% when the thickness was 0.8 μm, and 74% when the thickness was 0.2 μm. The average transmittance of the green filter was 33% when the thickness was 0.8 μm, and 75% when the thickness was 0.2 μm. The average transmittance of the blue filter was 30% when the thickness was 0.8 μm, and 74% when the thickness was 0.2 μm.
[0083]
FIG. 14 is a diagram plotting the average transmittance when the thickness of the color filter is variously changed. In the figure, reference numeral 1401 denotes a blue filter, 1402 denotes a green filter, and 1403 denotes a red filter. In any case, the thinner the color filter, the higher the average transmittance tends to be. The thickness of a normal pigment dispersion type color filter used in the transmission type is about 0.8 μm, but when such a color filter is used, it can be used under direct sunlight outdoors or special lighting such as a spotlight. Unless it was performed, only a display that was indistinguishable could be obtained. When the thickness is 0.23 μm or less, that is, when the average transmittance of any of the color filters is 70% or more, in a relatively bright room with an illuminance of about 1000 lux, for example, in an environment such as an office desk illuminated by a fluorescent lamp stand. Brightness that can be used comfortably was obtained. When the thickness was 0.18 μm or less, that is, when the average transmittance of each of the color filters was 75% or more, sufficient brightness was obtained even under normal room illumination light with an illuminance of about 200 lux. When the thickness was 0.8 μm or more, that is, when the average transmittance of all the color filters was 90% or less, the display could be performed to the extent that the color could be clearly recognized. As described above, the pigment-dispersed type color filter has a thickness of 0.23 μm or less, preferably 0.18 μm or less, and more preferably 0.08 μm or more.
[0084]
(Example 11)
FIG. 15 is a diagram showing a main part of the structure of a reflective color liquid crystal device according to Embodiment 11 of the present invention. In this embodiment, a color filter is provided only in a part of the light modulatable area in each dot. First, the configuration will be described. 1501 is an upper polarizer, 1502 is an element substrate, 1503 is a liquid crystal, 1504 is a counter substrate, 1505 is a lower polarizer, 1506 is a scattering reflector, and a counter electrode (scanning line) 1511 and a color are provided on the counter substrate 1504. A filter 1510 was provided, and a signal line 1507, a MIM element 1508, and a pixel electrode 1509 were provided over an element substrate 1502. The light modulatable area in one dot is an area where the concave ITO on the element substrate and the strip-shaped ITO on the opposing substrate overlap, and the outline is indicated by a broken line on the ITO of the opposing substrate. . (Refer to FIG. 20 which shows a similar outline, although it does not partially overlap with the color filter.)
[0085]
The counter electrode 1511 and the pixel electrode 1509 were formed of transparent ITO, and the signal line 1507 was formed of metal Ta. The MIM element is an insulating film Ta ₂ O ₅ Is sandwiched between metal Ta and metal Cr. The liquid crystal 1503 was a nematic liquid crystal twisted by 90 degrees, and the Δn of the liquid crystal and the cell gap d were selected so that Δn × d of the liquid crystal cell was 1.34 μm. The upper and lower polarizing plates were arranged such that their absorption axes were parallel to the rubbing axis of the adjacent substrate. This is the configuration of the TN mode which is the brightest and less colored. The color filter 1510 is composed of two colors of red (indicated by “R” in the figure) and cyan (indicated by “C” in the figure) which are complementary to each other. It was provided only in the section.
[0086]
FIG. 16 is a diagram showing the spectral characteristics of the color filter 1510. In FIG. 16, the horizontal axis represents the wavelength of light, and the vertical axis represents the transmittance. 1601 indicates the spectrum of the red filter, and 1602 indicates the spectrum of the cyan filter. The average transmittance obtained by simply averaging the transmittance in the wavelength range of 450 nm to 660 nm was 30% for the red filter and 58% for the cyan filter. However, this is the case where the color filter is provided on the entire surface, and when only a part of the color filter is provided, the average value in the light modulatable region will be referred to as the average transmittance.
[0087]
FIG. 17 shows the results obtained by variously changing the ratio of the area where the color filter is provided in the light modulatable region and obtaining the average transmittance at that time. Reference numeral 1701 denotes an average transmittance of a dot provided with a red filter, and 1702 denotes an average transmittance of a dot provided with a cyan filter.
[0088]
When the color filter area ratio was 100%, that is, when the color filters were provided on the entire surface, the display was so dark as to be indistinguishable unless exposed to direct sunlight outdoors or special lighting such as a spotlight. When the color filter area ratio is 45% or less, that is, when the average transmittance of all the color filters is 70% or more, a relatively bright room with an illuminance of about 1000 lux, for example, an environment such as an office desk illuminated by a fluorescent lamp stand is used. Underneath, a comfortable brightness was obtained. When the color filter area ratio was 35% or less, that is, when the average transmittance of each color filter was 75% or more, sufficient brightness was obtained even under normal room illumination light with an illuminance of about 200 lux. Further, when the color filter area ratio was 15% or more, that is, when the average transmittance of any of the color filters was 90% or less, display was possible to the extent that red and cyan could be distinguished. When the color filter area ratio was 25% or more, that is, when the average transmittance of each color filter was 90% or less, display was possible to the extent that colors could be clearly recognized. When any of the color filters was used, a high contrast ratio of 1:15 or more was obtained.
[0089]
The color filter used in the eleventh embodiment has the same spectral characteristics and the same brightness as the color filter used in the normal transmission type, except that a cyan color is used. Such a color filter is provided in an area of 45% or less, preferably 35% or less, and more preferably 15% or more, preferably 25% or more of the light modulatable region.
[0090]
In the first embodiment, the MIM element is used as the active element. However, this is slightly advantageous in increasing the aperture ratio. Therefore, if the same aperture ratio can be obtained even when the TFT element is used, the effect of the present invention can be obtained. No change.
[0091]
(Example 12)
The twelfth embodiment is also a reflection type color liquid crystal device in which a color filter is provided only in a part of a light modulatable area in each dot. The structure of the reflective color liquid crystal device in this embodiment is the same as that of the reflective color liquid crystal device of the eleventh embodiment shown in FIG. 15, but the twelfth embodiment differs in the characteristics of the color filter.
[0092]
FIG. 18 is a diagram illustrating the spectral characteristics of the color filters used in Example 12. In FIG. 18, the horizontal axis is the wavelength of light, and the vertical axis is the transmittance. 1801 indicates the spectrum of the red filter, and 1802 indicates the spectrum of the cyan filter. The average transmittance of the red filter was 41%, and the average transmittance of the cyan filter was 62%. This level of brightness is the maximum for a color filter that can be manufactured by a conventional process without problems such as dispersibility of the pigment.
[0093]
FIG. 19 shows the results obtained by changing the ratio of the area where the color filter is provided in the light modulatable region in various ways and calculating the average transmittance at that time. Reference numeral 1901 denotes an average transmittance of a dot provided with a red filter, and reference numeral 1902 denotes an average transmittance of a dot provided with a cyan filter.
[0094]
When the color filter area ratio was 100%, that is, when the color filter was provided on the entire surface, the display was dark and hard to see unless it was exposed to direct sunlight outdoors or special illumination such as a spotlight. When the color filter area ratio is 50% or less, that is, when the average transmittance of all the color filters is 70% or more, a relatively bright room with an illuminance of about 1000 lux, for example, an environment such as an office desk illuminated by a fluorescent lamp stand is used. Underneath, a comfortable brightness was obtained. When the color filter area ratio was 40% or less, that is, when the average transmittance of each color filter was 75% or more, sufficient brightness was obtained even under normal room illumination light with an illuminance of about 200 lux. When the color filter area ratio was 15% or more, that is, when the average transmittance of any of the color filters was 90% or less, it was possible to display such that red and cyan could be distinguished. When the color filter area ratio was 25% or more, that is, when the average transmittance of each color filter was 90% or less, display was possible to the extent that colors could be clearly recognized. When any of the color filters was used, a high contrast ratio of 1:15 or more was obtained.
[0095]
The color filter used in Example 12 is much brighter than the color filter used in a normal transmission type. It is desirable that such a color filter be provided in an area of 50% or less, preferably 40% or less, and 15% or more, preferably 25% or more of the light modulatable region.
[0096]
(Example 13)
FIG. 20 is a diagram illustrating a main part of a diagram structure of a reflective color liquid crystal device according to Embodiment 13 of the present invention. Also in this embodiment, the color filter is provided only in a part of the light modulatable area in each dot. The configuration will be described. 2001 is an upper polarizing plate, 2002 is an element substrate, 2003 is a liquid crystal, 2004 is a counter substrate, 2005 is a lower polarizing plate, 2006 is a scattering reflector, and a counter electrode (scanning line) 2011 and a color are provided on the counter substrate 2004. A filter 2010 was provided, and a signal line 2007, an MIM element 2008, and a pixel electrode 2009 were provided over an element substrate 2002. The light modulatable area in one dot is an area where the concave ITO on the element substrate and the strip-shaped ITO on the opposing substrate overlap, and the outline thereof is indicated by a broken line on the ITO of the opposing substrate.
[0097]
The color filter 2010 is composed of two colors of red (indicated by “R” in the figure) and cyan (indicated by “C” in the figure), which are complementary colors to each other, and is substantially at the center of the light modulatable area. Provided. It is desirable to arrange such that there is no other color filter around each color filter. With this arrangement, it is possible to display images with little color mixture. Because, usually, there is at least a distance between the color filter layer and the reflection plate by the thickness of the counter substrate, so that light incident through the red filter exits through the cyan filter, or The reverse causes color mixing, but the above arrangement reduces the probability.
[0098]
(Example 14)
FIG. 21 is a diagram showing a main part of the structure of a reflective color liquid crystal device according to Embodiment 14 of the present invention. Also in this embodiment, the color filter is provided only in a part of the light modulatable area in each dot. The configuration will be described. 2101 is an upper polarizing plate, 2102 is an element substrate, 2103 is a liquid crystal, 2104 is a counter substrate, 2105 is a lower polarizing plate, 2106 is a scattering reflector, and a counter electrode (scanning line) 2112 and a color are provided on the counter substrate 2104. A filter 2111 was provided, and a signal line 2107, a MIM element 2108, and a pixel electrode 2109 were provided over an element substrate 2102.
[0099]
The color filter 2111 is composed of two colors of red (indicated by “R” in the figure) and cyan (indicated by “C” in the figure), which are complementary to each other. It was divided into five areas and arranged in a checkered pattern. If a color filter is provided only in a part of the dot, a portion without the color filter is likely to be conspicuous white, but when divided and arranged in such a small area, there is an advantage that color mixture is good. Of course, the number of divisions may be two, but dividing the number into three or more is more effective.
[0100]
Further, a black mask 2110 (indicated by “BK” in the figure) was provided at a position covering the scanning line. This black mask has a particularly antireflection effect when the opposing substrate 2104 is located on the upper side and the element substrate 2102 is located on the lower side in FIG. Instead of using a black pigment, red, cyan, or a combination thereof may be used instead.
[0101]
(Example 15)
In the reflection type color liquid crystal device according to the fifteenth embodiment, the color filter is provided only in a part of the light modulatable area in each dot. The structure of the reflective color liquid crystal device in this embodiment is the same as that of the reflective color liquid crystal device of Embodiment 12 shown in FIG. 15, the reflective color liquid crystal device described in Embodiment 13 shown in FIG. 20, and the structure shown in FIG. This is the same as the reflective color liquid crystal device described in Example 14.
[0102]
The feature is that the color filter is provided at a position between the electrode and the liquid crystal. Generally, a color filter is often provided at a position between an electrode and a substrate in order to efficiently apply a voltage to a liquid crystal. However, by arranging as in the present embodiment, two new effects were obtained. One is to increase the viewing angle, and the other is to improve the color purity in the halftone.
[0103]
FIG. 22 is a diagram illustrating a voltage reflectance characteristic of a reflective color liquid crystal device according to Embodiment 15 of the present invention. The horizontal axis is the voltage effectively applied to the liquid crystal, and the vertical axis is the reflectivity normalized to 100% when no voltage is applied. Reference numeral 2201 denotes a characteristic of a region where a color filter is not provided in a light modulatable region, and reference numeral 2202 denotes a characteristic of a region where a color filter is provided. Due to the voltage drop due to the capacitance division, 2202 has a sharper voltage reflectance characteristic than 2201. In other words, a voltage is less likely to be applied to the liquid crystal in a region where the color filter is provided than in a region where the color filter is not provided. As described above, since two regions having different voltage application levels exist in one pixel, the effects disclosed in Japanese Patent Application Laid-Open Nos. 2-12 and 4-348323 (generally, "halftone method") are disclosed. ) Improves the viewing angle characteristics. Further, in the halftone display state, the area where the color filter is provided always has a higher reflectance, so that there is an effect that the color is displayed darker.
[0104]
(Example 16)
FIG. 23 is a diagram illustrating a structure of a color filter substrate of a reflective type color liquid crystal device according to Embodiment 16 of the present invention. In this embodiment, the color filter is provided only in a part of the light modulatable area in each dot. In the light modulatable area, the area where the color filter is not provided and the light modulatable area are not provided. In the region, a layer transparent in the visible light region was formed with substantially the same thickness as the color filter. (A) is a front view and (b) is a cross-sectional view. First, the configuration will be described. A rectangular area 2304 surrounded by a broken line in FIG. Reference numeral 2309 denotes a glass substrate, 2301 denotes a red filter, 2303 denotes a green filter, 2302 denotes a blue filter, 2305 denotes a gap between dots, hatching area 2308 denotes acrylic, 2307 denotes a protective film, and 2306 denotes an ITO transparent electrode.
[0105]
FIG. 25 shows the spectral characteristics of the color filters used here. In FIG. 25, the horizontal axis represents the wavelength of light and the vertical axis represents the transmittance. Reference numeral 2501 denotes a blue filter spectrum, reference numeral 2502 denotes a green filter spectrum, and reference numeral 2503 denotes a red filter spectrum. However, this is the characteristic when the color filter formation area is 100%. A color filter exhibiting such spectral characteristics was formed in one dot 2304 in FIG. 23 at an area ratio of 50%. As a result, spectral characteristics as shown in FIG. 26 were obtained on average within one dot. 26, the horizontal axis represents the wavelength of light and the vertical axis represents the transmittance. 2601 indicates the spectrum of the blue filter, 2602 indicates the spectrum of the green filter, and 2603 indicates the spectrum of the red filter.
[0106]
Further, acrylic 2308 was formed in a portion where the color filter was not formed in FIG. 23 to have the same thickness as the color filter. At this time, the thickness of each of the color filters 2301, 2302, 2303 and the acrylic 2308 is about 0.2 μm. Further, an acrylic transparent layer 2308 was formed also in a gap 2305 between dots without forming a light-shielding film (black stripe) formed between dots and the like used in a normal transmission type color liquid crystal device. Further, a protective film 2307, an ITO electrode 2306, and an alignment film (not shown) for aligning the liquid crystal are sequentially formed on the color filter, and are superposed on an MIM (metal-insulation-metal) active matrix substrate. And a liquid crystal device. At this time, the TN mode was used as the liquid crystal mode.
[0107]
FIG. 24 is a diagram illustrating a main part of the structure of the reflective color liquid crystal device according to the sixteenth embodiment. 2402 is an element substrate, 2403 is a counter substrate, 2406 is a MIM element, 2407 is a 1-dot display electrode, 2408 is a scanning line, 2401 is an upper polarizing plate, 2409 is a partially formed red color filter, and 2410 is a partially formed red color filter. A formed green color filter, a partially formed blue color filter 2411, an acryl 2412, a signal electrode 2413, a lower polarizer 2404, and an aluminum reflector 2405.
[0108]
In a reflection type color liquid crystal device using a substrate in which only a color filter is formed at an area ratio of 50% within one dot, the alignment of the liquid crystal is disturbed by a step between a portion where the color filter is formed and a portion where the color filter is not formed, and the contrast is 1: 8. On the other hand, a reflective color liquid crystal device using a substrate in which acryl is formed in a portion where a color filter is not formed with the same thickness as the color filter is capable of displaying high-quality images without disturbance of liquid crystal alignment. The contrast at this time was 1:20. FIG. 27 shows a configuration of a color filter in the case where an acrylic transparent layer is not formed in a portion where no color filter is formed. (A) is a front view and (b) is a cross-sectional view. Reference numeral 2707 denotes a glass substrate, 2701 denotes a partially formed red filter, 2703 denotes a partially formed green filter, 2702 denotes a partially formed blue filter, 2706 denotes a protective film, 2704 denotes one dot, and 2705 denotes a pixel. Is the gap between them. As is clear from the cross-sectional view of (b), the color filter surface has irregularities, and in such a surface state, the liquid crystal alignment is disturbed.
[0109]
In this embodiment, the color filter substrate of the present invention and the MIM substrate are combined, but a TFT substrate or a TFD (thin film diode) substrate may be used. In this embodiment, an active matrix reflective color liquid crystal device has been described. However, the present invention can be applied to a simple matrix reflective color liquid crystal device. The present invention is more effective when the unevenness of the substrate surface greatly affects the liquid crystal alignment as in the STN mode. In the present embodiment, the “mosaic array” is adopted as the color filter array. For example, a “triangle arrangement” and a “stripe arrangement” as described in H.321 may be used.
[0110]
(Example 17)
In the seventeenth embodiment, the color filter is provided only in a part of the light modulatable area in each dot. In the light modulatable area, the area where the color filter is not provided is different from the light modulatable area. In the region, a layer transparent in the visible light region was formed with substantially the same thickness as the color filter.
[0111]
FIG. 28 is a diagram illustrating a structure of a color filter substrate of a reflective color liquid crystal device according to Embodiment 17 of the present invention. (A) is a front view and (b) is a cross-sectional view. First, the configuration will be described. A rectangular area 2804 surrounded by a broken line in FIG. 2808 is a glass substrate, 2807 is an ITO electrode, 2801 is a red color filter, 2803 is a green color filter, 2802 is a blue color filter, and a hatched area 2806 is acrylic.
[0112]
FIG. 29 shows the spectral characteristics of the color filters used here. 29, the horizontal axis represents the wavelength of light and the vertical axis represents the transmittance. 2901 indicates the spectrum of the blue filter, 2902 indicates the spectrum of the green filter, and 2903 indicates the spectrum of the red filter. However, this is the characteristic when the color filter formation area is 100%. A color filter exhibiting such spectral characteristics was formed at an area ratio of 30% within one dot in FIG. As a result, spectral characteristics as shown in FIG. 26 were obtained on average within one dot.
[0113]
Further, acrylic 2807 was formed in a portion where the color filter was not formed in FIG. 28 with the same thickness as the color filter. At this time, the thickness of the color filter and the acrylic is about 0.8 μm, and the light-shielding film (black stripe) formed between the dots and the like normally used in a transmissive color liquid crystal device is not formed, and the acrylic is also formed between the dots. A 2807 transparent layer was formed. Further, an alignment film for aligning the liquid crystal was formed, and was superposed on the TFT substrate, thereby forming a liquid crystal device. At this time, a TN mode was adopted as the liquid crystal mode, a polarizing plate was attached to the outside of the glass substrate, and a silver reflector was disposed on the side opposite to the observation surface.
[0114]
In a reflection type color liquid crystal device using a substrate in which only a color filter is formed in one dot at an area ratio of 30%, the alignment of liquid crystal is disturbed by a step between a portion where a color filter is formed and a portion where no color filter is formed, and contrast is 1: 5. On the other hand, a reflective color liquid crystal device using a substrate in which acryl is formed in a portion where a color filter is not formed with the same thickness as the color filter is capable of displaying high-quality images without disturbance of liquid crystal alignment. The contrast at this time was 1:18.
[0115]
In this embodiment, the color filter substrate and the TFT substrate of the present invention are combined, but an MIM substrate or a TFD substrate may be used. In this embodiment, the active matrix reflective color liquid crystal device has been described. However, the present invention can be applied to a simple matrix reflective color liquid crystal device. The present invention is more effective when the unevenness of the substrate surface greatly affects the liquid crystal alignment as in the STN mode.
[0116]
In the sixteenth and seventeenth embodiments, three primary colors of red, green and blue are used for the color filters. However, complementary colors such as cyan 3001 and red 3002 shown in FIG. 30, magenta 3101 and green 3102 shown in FIG. 31, or yellow and blue are shown. Two related color filters may be used.
[0117]
(Example 18)
In Embodiments 16 and 17, the color filter is partially formed substantially at the center of one dot, but may be formed in an arrangement as shown in FIGS. In (a), the upper half or the lower half of one dot 3201 is a region 3202 where a color filter is formed, and the other half is a region 3203 where a color filter is not formed. In (b), the right half or the left half of one dot 3201 is a region where a color filter is formed 3202, and the other half is a region 3203 where a color filter is not formed. Further, as shown in FIGS. 32C and 32D, one dot 3201 may be divided into two or more, and a part may be a region 3202 where a color filter is formed, and the rest may be a region 3203 where a color filter is not formed. Even with the use of color filters of various patterns, a reflective color liquid crystal device with high image quality could be realized.
[0118]
(Example 19)
Table 1 shows the change in characteristics when the step between the color filter and the transparent layer in Example 16 was changed. As the step becomes smaller, both image quality and contrast are improved. If the step is 0.5 μm or less, a contrast of 1:10 or more can be obtained, and if it is 0.1 μm or less, a contrast of 1:15 or more can be obtained.
[Table 1]

[0119]
(Example 20)
In Examples 16 and 17, acrylic was used for the transparent layer filling the step between the color filter formed portion and the unformed portion, but a high quality reflective color liquid crystal device could be realized even when polyimide was used. Similarly, a reflective color liquid crystal device with high image quality could be realized by using polyvinyl alcohol for the transparent layer. Table 2 summarizes the results. Both the image quality and the contrast are improved as compared with the case where there is no transparent layer.
[Table 2]

[0120]
In Examples 16 and 17, a common aluminum reflector or silver reflector was used as the reflector. G. FIG. A holographic reflector (SID'95 DIGEST, PP. 176-179) published by Chen et al. Can also be used.
[0121]
(Example 21)
FIG. 33 is a diagram showing a main part of the structure of a reflective color liquid crystal device according to Embodiment 21 of the present invention. In this embodiment, a color filter is provided only for dots that are three-fourths or less of the total number of dots. The configuration will be described. 3301 is an upper polarizing plate, 3302 is an element substrate, 3303 is a liquid crystal, 3304 is a counter substrate, 3305 is a lower polarizing plate, 3306 is a scattering reflector, and a counter electrode (scanning line) 3311 and a color are provided on the counter substrate 3304. A filter 3310 was provided, and a signal line 3307, a MIM element 3308, and a pixel electrode 3309 were provided over an element substrate 3302.
[0122]
The color filter 3310 is composed of two colors of red (indicated by “R” in the figure) and cyan (indicated by “C” in the figure), which are complementary to each other. Was not provided. The color filters used here are the same as those in Example 1, and the spectral characteristics are shown in FIG.
[0123]
FIG. 34 is a diagram showing the arrangement of the color filters as viewed from above in FIG. In the figure, “R” indicates a dot provided with a red filter, “C” indicates a dot provided with a cyan filter, and “W” indicates a dot without a color filter. A red filter was provided for 1/3 of the total dots, a cyan filter was provided for 1/3 of the dots, and a color filter was not provided for the remaining 1/3 of the dots. 34 (a), (b), (c), and (d) show the distribution of on dots and off dots when displaying white, red, cyan, and black, respectively. The hatched dots are on dots, that is, a dark state, and the unhatched dots are off dots, that is, a bright state. When the display is performed in this manner, since a color display is performed with ／ of the entire dots, a display brighter than usual can be performed. Also in the case of displaying halftones in color display, there is a merit that a vivid color can always be displayed by adjusting the brightness mainly with dots without a color filter. For example, in the case of displaying darker red, all dots with a red filter are turned off, dots with a cyan filter are turned on, and dots without a color filter are turned on half.
[0124]
Another color filter arrangement is shown in FIG. A red filter was provided for １ ／ of the total dots, a cyan filter was provided for ド ッ ト of the dots, and a color filter was not provided for the remaining ド ッ ト of the dots. Further, (a), (b), (c), and (d) of FIG. 35 show distributions of on dots and off dots when displaying white, red, cyan, and black, respectively. When the display is performed in this manner, a color display is performed with ３ of the entire dots, so that a brighter display than the color filter arrangement of FIG. 35 is possible.
[0125]
As another example, FIG. 36 shows an arrangement in which three red, green and blue color filters are used. In the figure, “R” indicates a dot provided with a red filter, “G” indicates a dot provided with a green filter, “B” indicates a dot provided with a blue filter, and “W” indicates a dot without a color filter. I have. A red filter is provided for 1/6 of the entire dot, a green filter is provided for 1/6 of the dot, a blue filter is provided for 1/6 of the dot, and no color filter is provided for the remaining 1/2 of the dot. Was. 36 (a), (b), (c), and (d) of FIG. 36 show the distribution of on dots and off dots when displaying white, red, green, and blue, respectively. When display is performed in this manner, bright display is possible because color display is performed with 4/6 dots of the whole.
[0126]
Also, a red filter is provided for 1/4 of the entire dot, a green filter is provided for 1/4 of the dot, a blue filter is provided for 1/4 of the dot, and a color filter is provided for the remaining 1/4 of the dot. No configuration is possible. When display is performed in this manner, bright display is possible because color display is performed with half of the entire dot.
[0127]
(Example 22)
37A and 37B are diagrams schematically illustrating the structure of a reflective color liquid crystal device according to Example 22 of the present invention, wherein FIG. 37A is a front view and FIG. 37B is a cross-sectional view. In this embodiment, a color filter is provided over the entire effective display area. The configuration will be described. Reference numeral 3701 denotes a frame case, 3702 denotes an upper polarizing plate, 3703 denotes an upper substrate, 3704 denotes a color filter in a hatched area, 3705 denotes a lower substrate, and 3706 denotes a polarizing plate with a reflector. Since the drawings are complicated, transparent electrodes, nonlinear elements, signal lines, alignment films, and the like are omitted. Reference numeral 3711 denotes a drive display area, 3712 denotes an effective display area, and 3713 denotes an area provided with a color filter. (B) is a horizontal sectional view, but the vertical sectional view is also the same as (b). Note that the terms “drive display area” and “effective display area” are referred to in ED-2511A of the Japan Electronic Machinery Manufacturers Association (EIAJ) as “a region having a display function in a liquid crystal display device”, “a drive display region and The area that is effective as a subsequent screen "is defined. In other words, the drive display area is an area where a voltage can be applied to the liquid crystal, and the effective display area is the entire liquid crystal panel area that is not hidden by the frame case.
[0128]
The feature of the twenty-second embodiment is that an area 3713 provided with a color filter is the same as or wider than the effective display area 3712. With this configuration, the reflective color liquid crystal device of Example 22 has the advantage that the display looks bright. Normally, in a transmissive color display, a color filter is provided only in a driving display area, and a black mask made of metal or resin is provided in an area outside the driving display area. However, in a reflective type color display, a metal black mask cannot be used because it is glaring. In addition, the cost of the resin black mask is increased because the original color filter is not provided with the black mask. However, if nothing is provided outside the driving display area, the outside becomes bright and the driving display area looks relatively dark. Therefore, it is effective to provide a color filter similar to that inside the drive display area, preferably in the same pattern, outside the drive display area in order to make the display look bright.
[0129]
(Example 23)
In a transmission type color liquid crystal device, a black mask is generally provided outside a dot. However, when a black mask is provided in a reflection type color liquid crystal device, high contrast is obtained, but display becomes extremely dark. In particular, in a liquid crystal mode in which parallax is inevitable, such as a TN mode or an STN mode, light is absorbed by a black mask twice when light enters and when light is emitted, so that the brightness is approximately proportional to the square of the aperture ratio. There is a property that. Therefore, a black mask cannot be provided in the reflection type color liquid crystal device. Conversely, if no light absorber is provided outside the dots, the contrast is significantly reduced, which is not preferable. Therefore, Embodiment 23 of the present invention is characterized in that a black mask is not provided outside a dot, and a color filter having absorption equal to or smaller than that of a region inside the dot is provided instead.
[0130]
FIG. 38 is a diagram showing a color filter arrangement of a reflection type color liquid crystal device in Embodiment 23 of the present invention. As described above, in this embodiment, the black mask was not provided in the area outside each dot, and instead, a color filter having absorption equal to or smaller than the area in the dot was provided. Although the basic configuration and the spectral characteristics of the color filters are the same as those in FIGS. 6 and 3 of the fifth embodiment, the arrangement of the color filters in the area outside the dots is devised. In FIG. 38, the “horizontally convex” region 3801 is a region where the counter electrode and the pixel electrode overlap and an electric field is applied to the liquid crystal, and corresponds to the above-described dot. An area 3802 hatched diagonally from upper right to lower left is a cyan filter, and an area 3803 hatched on a cross is a red filter.
[0131]
In (a) of FIG. 38, the red filter and the cyan filter are arranged so as to be in close contact with each other outside the dots. In (b), filters are provided outside the dots, but are arranged apart from each other. In (c), a red filter is arranged outside the dot. Since each of them has the same or smaller absorption than the inside of the dot but is not zero in the area outside the dot, a bright and high-contrast display can be obtained. The respective characteristics are as follows: (a) a contrast ratio of 1:15 at a reflectance of 30% in white display, (b) a contrast ratio of 1:13 at a reflectance of 33%, and (c) a contrast ratio of 1:16 at a reflectance of 29%. there were.
[0132]
(Example 24)
FIG. 39 is a diagram showing a color filter arrangement of a reflective color liquid crystal device according to Embodiment 24 of the present invention. Also in this embodiment, the black mask is not provided in the area outside each dot, but a color filter having absorption equal to or smaller than the area in the dot is provided instead. The basic configuration and the spectral characteristics of the color filters are the same as those in FIGS. 8 and 12 of the ninth embodiment, but the arrangement of the color filters in the area outside the dots is devised. In FIG. 39, the “horizontally convex” area 3901 is an area where the counter electrode and the pixel electrode overlap and an electric field is applied to the liquid crystal, and corresponds to the dot of Example 23. An area 3902 hatched diagonally from upper left to lower right is a blue filter, an area 3903 hatched diagonally from upper right to lower left is a green filter, and an area 3904 hatched to a cross is a red filter. is there.
[0133]
In (a) of FIG. 39, filters of three colors are provided outside the dots, but are arranged apart from each other. The separation distance was set in anticipation of the maximum misalignment at the time of producing the color filter. That is, FIG. 39 (b) shows the arrangement of the color filters when the assumed maximum misalignment occurs. Even in this case, the color filters of different colors are prevented from overlapping each other. The overlapping of the color filters is almost synonymous with the presence of the black mask, so that this must be avoided as much as possible. By arranging the color filters as described above, a bright and high-contrast reflective color display was achieved.
[0134]
(Example 25)
FIG. 40 is a diagram showing a main part of a reflective color liquid crystal device according to Embodiment 25 of the present invention. Also in this example, the black mask was not provided in the region outside each dot, and instead, a color filter having absorption equal to or smaller than the region in the dot was provided. First, the configuration will be described. 4001 is an upper polarizing plate, 4002 is a counter substrate, 4003 is a liquid crystal, 4004 is an element substrate, 4005 is a lower polarizing plate, 4006 is a scattering reflector, and a color filter 4007 and a counter electrode (scanning) are provided on the counter substrate 4002. Line) 4008, and a signal line 4009, a pixel electrode 4010, and an MIM element 4011 were provided over the element substrate 4004. This color filter has a stripe arrangement commonly used in data displays such as PCs. Note that the spectral characteristics of the color filters are the same as in FIG. 12 of the ninth embodiment.
[0135]
FIG. 41 is a diagram showing a color filter arrangement of a reflection type color liquid crystal device in Embodiment 25 of the present invention. In FIG. 41, the “horizontally convex” area 4101 is an area where the counter electrode and the pixel electrode overlap and an electric field is applied to the liquid crystal, and corresponds to the dot of Example 23. A region 4102 hatched diagonally from upper left to lower right is a blue filter, a region 4103 hatched diagonally from upper right to lower left is a green filter, and a region 4104 hatched to a cross is a red filter. is there.
[0136]
In FIG. 41A, three color filters are also provided outside the dots, but they are continuously arranged vertically and separated from each other on the left and right. The separation distance was set in anticipation of the maximum misalignment at the time of producing the color filter. That is, FIG. 41B shows the arrangement of the color filters in the case where the assumed maximum misalignment occurs. Even in this case, the color filters of different colors are prevented from overlapping each other. By arranging the color filters as described above, a bright and high-contrast reflective color display was achieved.
[0137]
(Example 26)
FIG. 42 is a sectional view showing a main part of the structure of a reflective color liquid crystal device according to Embodiment 26 of the present invention. In this embodiment, a color filter is provided on the outer surface of the substrate located on the side of the reflection plate among the pair of substrates. The configuration will be described. 4201 is an upper polarizing plate, 4202 is an element substrate, 4203 is a liquid crystal, 4204 is a counter substrate, 4205 is a lower polarizing plate, 4206 is a scattering reflector, and a signal line 4207 and a pixel electrode 4208 are provided on the element substrate 4202. A counter electrode (scanning line) 4209 was provided on the counter substrate 4204. Although not shown in this cross-sectional view, the signal line and the pixel electrode are connected via an MIM element. A red filter 4210, a green filter 4211, and a blue filter 4212 are provided on the surface of the counter substrate 4204 on the side of the reflector.
[0138]
The spectral characteristics of the color filter have the characteristics shown in FIG. 12 if provided on the entire surface of the dot, and the characteristics shown in FIGS. 16 and 18 depending on the ratio if provided on a part of the dot. Let
[0139]
By providing the color filter outside the substrate in this way, an inexpensive color filter can be used. This color filter may be separately provided on a film or the like, and may be laminated later. In particular, by providing a color filter only for a part of the dots, there is an advantage that an assembling margin is expanded and a viewing angle is widened.
[0140]
(Example 27)
In the twenty-seventh embodiment, a non-linear element is provided corresponding to each dot on the inner surface of the substrate located on the reflection plate side of the pair of substrates. The structure of the reflective color liquid crystal device in this embodiment is the same as that of FIG. 1 of the first embodiment, FIG. 6 of the sixth embodiment, and FIG. 8 of the seventh embodiment. The feature is that MIM elements 111, 611, and 811 are provided on the substrates 104, 604, and 804 located on the reflection plate side. By arranging in this manner, unnecessary surface reflection is reduced and a high contrast is obtained, as compared with the case where the MIM elements are provided on the substrates 102, 602, and 802. There are three reasons. One is that the reflections by the signal lines 109, 609, 809 and the MIM element are partially absorbed by the color filters 107, 607, 807, and the second is that the signal lines themselves are formed by superposing metal Cr on metal Ta. The structure is such that Cr has a lower reflectance than Ta. Third, the reflected light passes through the liquid crystal layers 103, 603, and 803 to cause absorption by birefringence interference.
[0141]
(Example 28)
In Example 28, a non-linear element was provided corresponding to each dot on the inner surface of one of the pair of substrates, and this was connected in a direction parallel to the short side of the dot. The overall structure of the reflective color liquid crystal device in this embodiment is the same as, for example, FIG. The feature lies in the wiring method of the MIM element.
[0142]
FIG. 43 is a diagram illustrating a wiring method of the MIM elements of the reflective color liquid crystal device in Example 28. Reference numeral 4301 denotes a signal line, reference numeral 4302 denotes an MIM element, and reference numeral 4303 denotes a pixel electrode. Since the pixel electrodes correspond to the red, green, and blue color filters of the counter substrate, the correspondence is indicated by “R”, “G”, and “B” on the pixel electrodes.
[0143]
Each dot in FIG. 43 has a vertically long shape, and one square pixel is formed by three dots arranged horizontally. This is a configuration often seen in data displays for personal computers. At this time, the signal lines are wired in parallel with the short sides of the dots, that is, in the horizontal direction. Such wiring has the effect of reducing the number of wirings and increasing the aperture ratio. Here, the aperture ratio is a ratio occupied by a region excluding an opaque portion such as a metal.
[0144]
This is compared with the conventional configuration. FIG. 44 is a diagram showing a wiring method of a (transmissive) color liquid crystal device using a conventional MIM element. 4401 is a signal line, 4402 is a MIM element, and 4403 is a pixel electrode. The dot pitch is the same as in FIG. 43, and the dots have a vertically long shape, but the signal lines are wired in parallel with the long sides of the dots, that is, in the vertical direction. With this wiring, the number of wirings is three times that of FIG. 43 and the aperture ratio is low. Conventionally, such wiring was performed because, in a horizontally long panel, the distance in the vertical direction was shorter than that in the horizontal panel. This is because the aperture ratio does not change even if wiring is performed.
[0145]
When the aperture ratio is high, the display becomes bright. The effect of the aperture ratio on the brightness, particularly the remarkable effect in the reflective configuration having parallax, has already been described in detail in Examples 23 to 25.
[0146]
(Example 29)
In Example 29, the driving area ratio is 60% or more and 85% or less. FIG. 45 shows the characteristics of the reflective color liquid crystal device in this embodiment. The relationship between the drive area ratio and the contrast and the relationship between the drive area ratio and the reflectance when the drive area ratio is changed from 50% to 100% by taking the same configuration as the second embodiment are shown. Here, the driving area ratio is defined as a ratio of a region where liquid crystal is driven in a region excluding an opaque portion such as a metal wiring or an MIM element in a pixel. The horizontal axis represents the driving area ratio, and the vertical axis represents the contrast and the reflectance. 4501 is the contrast of the present embodiment, 4502 is the contrast of the comparative example, 4503 is the reflectance at the time of cyan display of the present embodiment, and 4504 is the comparative example. This is the reflectance at the time of cyan display.
[0147]
If the driving area ratio is 60% or more, a good contrast of 1: 5 or more can be obtained. If the driving area ratio is 85% or less, good brightness of 23% or more in cyan display can be obtained.
[0148]
(Example 30)
In a reflection type color liquid crystal device, the characteristics of the scattering reflector greatly affect brightness, contrast, and viewing angle characteristics. There are various types of scattering reflectors, from those with low scattering properties such as mirror surfaces to those with strong scattering properties such as paper, which are selected according to the surrounding environment. It is desirable that the material has low scattering property with emphasis on the contrast and contrast.
[0149]
FIG. 46 and FIG. 47 are diagrams showing the characteristics of the reflection plate of the reflection type color liquid crystal device in Embodiment 30 of the present invention. The reflector has a scattering characteristic such that when a light beam enters the reflector, 80% or more of the light is reflected within a 30-degree cone centered on the specular reflection direction.
[0150]
In FIG. 46, reference numeral 4604 denotes a scattering reflector, 4601 denotes light incident on the surface of the scattering reflector at an angle of 45 °, 4602 denotes regular reflection light thereof, and 4603 denotes a 30-degree cone centered on regular reflection. In FIG. 47, the horizontal axis represents the light receiving angle of the reflected light, and the vertical axis represents the relative reflection intensity. The reflector of Example 30 has a characteristic that about 95% of the incident light is reflected into the 30 ° cone shown in FIG. If the ratio is less than 80%, a contrast ratio of 1:10 or more cannot be obtained under a normal indoor environment.
[0151]
FIG. 48 shows the result of computer simulation for reference. The horizontal axis of the figure is the ratio of light reflected in the 30-degree cone shown in FIG. 46, and the vertical axis of the figure is the brightness and contrast ratio. As the light source, perfectly scattered white light such as an integrating sphere was assumed, and the light reflected in the normal direction of the substrate was calculated. The brightness was 100% of the brightness of the standard white plate. As is clear from the simulation results, the higher the proportion of light reflected within the 30-degree cone, that is, the lower the degree of scattering of the reflector, the brighter and higher-contrast display is obtained. However, it has been experimentally confirmed that a reflecting plate in which light larger than 95% of the incident light is reflected into the 30-degree cone has extremely narrow viewing angle characteristics and is not practical.
[0152]
(Example 31)
FIG. 49 is a diagram illustrating a main part of the structure of a reflective color liquid crystal device according to Embodiment 31 of the present invention. The reflector is a semi-transmissive reflector, and has a backlight on the back thereof. First, the configuration will be described. 4901 is an upper polarizing plate, 4902 is a counter substrate, 4903 is a liquid crystal, 4904 is an element substrate, 4905 is a lower polarizing plate, 4906 is a semi-transmissive reflector, 4912 is a backlight, and a color filter 4907 is provided on the counter substrate 4902. And a counter electrode (scanning line) 4908, and a signal line 4909, a pixel electrode 4910, and an MIM element 4911 are provided over the element substrate 4904. Further, the color filter has the same spectral characteristics as FIG. 3 of the second embodiment.
[0153]
Since the transflective plate has a reflectance of about 70% of that of a normal scattering reflector, when used in the reflection mode without turning on the backlight, the reflectance in white display is about 24%. Become. On the other hand, in the transmission mode in which the backlight is turned on, the transmittance is about 22%, and the surface luminance is 400 cd / m 2. ² A sufficient backlight can be obtained even with a monochrome backlight. Although the characteristics of the color filter as shown in FIG. 3 are originally insufficient for displaying a color by transmission, the use of a semi-transmissive reflector increases the color purity by reflection of ambient light even in a transmission mode. effective.
[0154]
It is desirable that the transflective plate reflects 80% or more of the incident light in order to obtain a bright display. Inevitably, the display will be dark when used in the transmissive mode, but pursuing the brightness in the transmissive mode tends to result in unsatisfactory results in both the transmissive display and the reflective display. Dividing the transmissive mode from being barely visible in the darkness gives a better display that is more acceptable to the market.
[0155]
(Example 32)
In Example 32, the liquid crystal was a nematic liquid crystal twisted by approximately 90 degrees, and two polarizing plates were arranged so that the transmission axes thereof were orthogonal to the rubbing directions of the adjacent substrates. The basic structure of the reflection type color liquid crystal device in this embodiment and the spectral characteristics of the color filters are the same as those in FIGS. The feature is that the cell condition of the TN mode is optimized for the reflection type color liquid crystal device.
[0156]
FIG. 50 is a diagram illustrating a relationship between axes of the reflective color liquid crystal device according to the 32nd embodiment. Reference numeral 5021 denotes the left-right direction (longitudinal direction) of the liquid crystal panel, 5001 denotes the transmission axis direction of the upper polarizing plate, 5002 denotes the rubbing direction of the opposing substrate located on the upper side, 5003 denotes the rubbing direction of the element substrate located on the lower side, and 5004 Is the transmission axis direction of the lower polarizing plate. Here, the angle 5011 between the rubbing direction of the opposing substrate and the left-right direction of the liquid crystal panel is 45 °, the angle 5012 between the transmission axis direction of the upper polarizer and the rubbing direction of the opposing substrate is 90 °, and the twist angle 5013 of the liquid crystal is The angle 5014 between the transmission axis direction of the lower polarizing plate and the rubbing direction of the element substrate was set to 90 ° to the right 90 °. With this arrangement, the molecules at the center of the liquid crystal layer rise from the observer side (that is, the lower side in the figure) when a voltage is applied, and display with high contrast and in which shadows are hard to see is possible, in combination with the viewing angle characteristics of the TN liquid crystal. The arrangement in which the transmission axis of the polarizing plate is orthogonal to the rubbing direction of the adjacent substrate (so-called O mode) is more preferable because the color change due to the viewing angle direction is smaller than that in the parallel arrangement (so-called E mode).
[0157]
By setting the birefringence Δn of the liquid crystal material to 0.189 and the cell gap to 7.1 μm, Δn × d of the liquid crystal cell was set to 1.34 μm. This is the brightest and least colored condition when a non-selection voltage is applied. There is a problem that the display color becomes bluish when Δn × d <1.30 μm, and the display becomes dark when Δn × d> 1.40 μm. Absent.
[0158]
(Example 33)
In Example 33, the product Δn × d of the birefringence Δn of the liquid crystal and the thickness d of the liquid crystal layer is larger than 0.34 μm and smaller than 0.52 μm. The basic configuration of the reflective color liquid crystal device in this embodiment is the same as that in FIG. 1 of the second embodiment. The feature is that the cell condition of the TN mode is further optimized for the reflection type color liquid crystal device.
[0159]
FIG. 50 is a diagram showing the relationship between the axes of the reflective color liquid crystal device in Example 33. Reference numeral 5021 denotes the left-right direction (longitudinal direction) of the liquid crystal panel, 5001 denotes the transmission axis direction of the upper polarizing plate, 5002 denotes the rubbing direction of the opposing substrate located on the upper side, 5003 denotes the rubbing direction of the element substrate located on the lower side, and 5004 Is the transmission axis direction of the lower polarizing plate. Here, the angle 5011 between the rubbing direction of the opposing substrate and the left-right direction of the liquid crystal panel is 45 °, the angle 5012 between the transmission axis direction of the upper polarizer and the rubbing direction of the opposing substrate is 90 °, and the twist angle 5013 of the liquid crystal is The angle 5014 between the transmission axis direction of the lower polarizing plate and the rubbing direction of the element substrate was set to 90 ° to the right 90 °. With this arrangement, the molecules at the center of the liquid crystal layer rise from the observer side (that is, the lower side in the figure) when a voltage is applied, and display with high contrast and in which shadows are hard to see is possible, in combination with the viewing angle characteristics of the TN liquid crystal. The arrangement in which the transmission axis of the polarizing plate is orthogonal to the rubbing direction of the adjacent substrate (so-called O mode) is more preferable because the color change due to the viewing angle direction is smaller than that in the parallel arrangement (so-called E mode).
[0160]
Here, the birefringence Δn of the liquid crystal material was set to 0.084, and panels having different Δn × d were produced by changing the cell gap.
[0161]
FIG. 51 shows the relationship between Δn × d and the reflectance during white display. Reference numeral 5101 denotes the reflectance for each Δn × d in the embodiment, and 5102 denotes the reflectance for each Δnxd in the comparative example. The measurement was performed using an integrating sphere so that light was uniformly incident from all directions. The reflectance was set to 100% for a standard white plate. From FIG. 51, it can be seen that the display angle becomes darker because Δn × d becomes larger, the viewing angle becomes narrower, and the utilization efficiency of obliquely incident light decreases. Therefore, to obtain a bright display, it is preferable to use a so-called first minimum condition in which Δn × d is small. However, the first minimum condition has a drawback that the display is greatly colored. For this reason, the conventional reflection type monochrome liquid crystal device uses a condition where Δn × d is large as in Embodiment 32. However, in the reflection type color liquid crystal device, slight coloring can be corrected by adjusting the color filter. In Example 33, by adjusting the color filter so as to have a high transmittance on the long wavelength side, white was almost colorless at any Δn × d, and a display with little change in coloring was obtained.
[0162]
The highest reflectance is exhibited when Δn × d is 0.42 μm, and the reflectance corresponding to Δnxd in the vicinity is shown in Table 3 below.
[Table 3]

[0163]
Thus, by setting Δn × d to be larger than 0.34 μm and smaller than 0.52 μm, a bright display can be obtained.
[0164]
When Δn × d is smaller than 0.40 μm, a bright display is obtained because the viewing angle is wide. On the other hand, since the brightness in the front direction is low and the image looks dark under a spot light source, Δn × d is It is more preferably 0.40 μm or more. Further, by setting the thickness to 0.48 μm or less, extremely large coloring can be eliminated. Therefore, Δn × d is preferably 0.48 μm or less. The most preferable Δn × d is 0.42 μm at which the maximum brightness is obtained.
[0165]
(Example 34)
In Example 34 of the present invention, the liquid crystal was a nematic liquid crystal twisted by 90 degrees or more, and two polarizing plates and at least one retardation film were arranged. FIG. 52 is a diagram illustrating a main part of a reflective color liquid crystal device according to a thirty-fourth embodiment. First, the configuration will be described. 5201 is an upper polarizing plate, 5202 is a phase difference film, 5203 is an upper substrate, 5204 is a liquid crystal, 5205 is a lower substrate, 5206 is a lower polarizing plate, 5207 is a scattering reflector, and a color filter is on the upper substrate 5203. 5208 and a scanning electrode 5209 are provided, and a signal electrode 5210 is provided over the lower substrate 5205. The retardation film 5202 is a uniaxially stretched polycarbonate film and exhibits a positive retardation. Further, the color filter has the same spectral characteristics as FIG. 3 of the second embodiment.
[0166]
FIG. 53 is a diagram illustrating the relationship between the axes of the reflective color liquid crystal device according to Example 34. 5321 is the horizontal direction (longitudinal direction) of the liquid crystal panel, 5301 is the transmission axis direction of the upper polarizing plate, 5302 is the rubbing direction of the upper substrate, 5303 is the rubbing direction of the lower substrate, and 5304 is the transmission axis of the lower polarizing plate. The direction 5305 is the stretching direction of the retardation film. Here, the angle 5311 formed by the rubbing direction of the upper substrate and the left-right direction of the liquid crystal panel is set to 30 °, and the angle 5314 formed by the transmission axis direction of the upper polarizer and the stretching direction of the retardation film is set to 54 °. The angle 5315 between the direction and the rubbing direction of the upper substrate is 80 °, the twist angle 5312 of the liquid crystal is 240 ° left, and the angle 5313 between the transmission axis direction of the lower polarizer and the rubbing direction of the lower substrate is 43 °. Set. With this arrangement, the molecules at the center of the liquid crystal layer rise from the observer side (that is, the lower side in the figure) when a voltage is applied, and together with the viewing angle characteristics, a high-contrast display in which shadows are difficult to see becomes possible.
[0167]
This is a phase difference plate compensation type STN mode proposed in Japanese Patent Publication No. 3-50249, and is characterized in that multiplex driving up to a duty ratio of 1/480 can be performed with a simple matrix. Further, despite the use of the same color filter as in the second embodiment, the aperture ratio is high because the signal line and the MIM element are unnecessary, and the reflectivity at the time of white display is as high as 33%. . Although the contrast ratio was relatively low at 1: 8, the number of retardation films for performing color compensation was increased by one and multi-line simultaneous selection driving was performed in accordance with the method disclosed in JP-A-6-348230. , And the same color can be displayed with the same contrast as that provided with the MIM element.
[0168]
(Example 35)
Also in Example 34 of the present invention, the liquid crystal was a nematic liquid crystal twisted by 90 degrees or more, and two polarizing plates and at least one retardation film were arranged. FIG. 55 is a diagram illustrating a main part of the structure of the reflective color liquid crystal device according to Example 35. First, the configuration will be described. 5501 is an upper polarizing plate, 5502 is a phase difference film, 5503 is an upper substrate, 5504 is a liquid crystal, 5505 is a lower substrate, 5506 is a lower polarizing plate, 5507 is a scattering reflector, and a color filter is on the upper substrate 5503. 5508 and a scanning electrode 5509 were provided, and a signal electrode 5510 was provided over the lower substrate 5505. The retardation film 5502 is a uniaxially stretched polycarbonate film and has a positive retardation of 587 nm. The product Δn × d of the liquid crystal Δn and the cell gap is 0.85 μm.
[0169]
FIG. 53 is a diagram illustrating the relationship between the axes of the reflective color liquid crystal device according to Example 35. 5321 is the horizontal direction (longitudinal direction) of the liquid crystal panel, 5301 is the transmission axis direction of the upper polarizing plate, 5302 is the rubbing direction of the upper substrate, 5303 is the rubbing direction of the lower substrate, and 5304 is the transmission axis of the lower polarizing plate. The direction 5305 is the stretching direction of the retardation film. Here, the angle 5311 formed by the rubbing direction of the upper substrate and the left-right direction of the liquid crystal panel is set to 30 °, and the angle 5314 formed by the transmission axis direction of the upper polarizing plate and the stretching direction of the retardation film is set to 38 °. The angle 5315 between the direction and the rubbing direction of the upper substrate is 92 °, the twist angle 5312 of the liquid crystal is 240 ° left, and the angle 5313 between the transmission axis direction of the lower polarizing plate and the rubbing direction of the lower substrate is 50 °. Set.
[0170]
FIG. 54 is a diagram illustrating the spectral characteristics of the color filters of the reflective color liquid crystal device in Example 35. In FIG. 54, the horizontal axis represents the light wavelength, and the vertical axis represents the transmittance. 5401 indicates the spectrum of the red filter, 5402 indicates the spectrum of the green filter, and 5403 indicates the spectrum of the blue filter. The color filter characteristics are optimized so that white balance can be obtained from the spectral characteristics 5411 in the off state when the color filters are removed from the liquid crystal device. Here, the green filter and the blue filter have a transmittance of 50% or more in a wavelength range of 450 nm to 660 nm. The minimum transmittance of the red filter for light having a wavelength in the range of 450 nm to 660 nm is distinctly smaller than that of the blue filter and the green filter. By using such a red filter, it is possible to vividly display red that appeals to human eyes. In order to compensate for the darkening of red, the spectrum 5403 of the blue filter was set close to cyan.
[0171]
This is a phase difference plate compensation type STN mode proposed in Japanese Patent Publication No. 3-50249, and is characterized in that multiplex driving up to a duty ratio of 1/480 can be performed with a simple matrix. However, in the conventional phase difference plate compensation type STN mode, even though black-and-white display can be performed, only cyan-like white can be obtained. However, the reflective color liquid crystal device of Example 35 was able to display white much closer to neutral than before by optimizing the color filters. Further, despite the use of a color filter having similar characteristics to that of the ninth embodiment, the aperture ratio is high because the signal line and the MIM element are unnecessary, and the reflectivity in white display is 29%, which is very bright. It is possible.
[0172]
(Example 36)
In Example 36 of the present invention, a reflection plate was provided between a pair of substrates, and only one polarizing plate was disposed. FIG. 56 is a diagram illustrating a main part of a reflective color liquid crystal device according to Example 36. First, the configuration will be described. 5601 is an upper polarizer, 5602 is a counter substrate, 5603 is a liquid crystal, and 5604 is an element substrate. A color filter 5605 and a counter electrode (scanning line) 5606 are provided on the counter substrate 5602, and a signal is provided on the element substrate 5604. A line 5607, a pixel electrode 5608 also serving as a scattering reflector, and an MIM element 5609 were provided. The pixel electrode serving also as the scattering reflector was obtained by forming irregularities on the surface of a metal aluminum sputtered film by a mechanical or chemical method. Further, the color filter has the same spectral characteristics as FIG. 3 of the second embodiment.
[0173]
FIG. 57 is a diagram illustrating a relationship between axes of the reflective color liquid crystal device according to Example 36. Reference numeral 5721 denotes a horizontal direction (longitudinal direction) of the liquid crystal panel, reference numeral 5701 denotes a transmission axis direction of the upper polarizing plate, reference numeral 5702 denotes a rubbing direction of the upper substrate, and reference numeral 5703 denotes a rubbing direction of the lower substrate. Here, the angle 5711 between the rubbing direction of the upper substrate and the left-right direction of the liquid crystal panel is 62 °, the angle 5712 between the transmission axis direction of the upper polarizer and the rubbing direction of the upper substrate is 94 °, and the twist angle 5713 of the liquid crystal is It was set at 56 ° to the right. With this arrangement, the molecules at the center of the liquid crystal layer rise from the observer side (that is, the lower side of the figure) when a voltage is applied, and high contrast display is possible in combination with the viewing angle characteristics.
[0174]
This is a single-polarizer type nematic liquid crystal mode proposed in Japanese Patent Application Laid-Open No. 3-223715, and high-contrast black and white display can be performed without using a lower polarizer. The feature is that a reflection plate can be provided.
[0175]
This reflective color liquid crystal device has a reflectivity of 30% in white display, a contrast ratio of 1:10, and can display four colors of white, red, cyan and black, and the red display color is x = 0.38. y = 0.31, the cyan display color was x = 0.28, and y = 0.32. There is no shadow on the display, and the viewing angle dependency is very small. Further, for example, light incident through the red filter always exits through the red filter, so that color turbidity does not occur, and a bright display with high color purity was achieved.
[0176]
Although the MIM element is used in the above embodiment, a TFT element can be used instead. FIG. 58 is a diagram showing a main part of a structure in a case where a reflective color liquid crystal device of the present invention in which a reflecting plate is provided between a pair of substrates and only one polarizing plate is arranged is manufactured using a TFT element. First, the configuration will be described. Reference numeral 5801 denotes an upper polarizing plate; 5802, a counter substrate; 5803, a liquid crystal; 5804, an element substrate; a color filter 5805 and a counter electrode (common electrode) 5806 provided on the counter substrate 5802; A signal line 5807, a source signal line 5808, a TFT element 5809, and a pixel electrode 5810 also serving as a scattering reflector were provided. In the case of the MIM element, the metal wiring only runs in the vertical direction, but in the case of the TFT element, the metal wiring runs in the vertical and horizontal directions, so that the aperture ratio decreases. Fortunately, this embodiment 36 does not require a lower polarizer. Therefore, when a TFT element is used, it is preferable to adopt a method in which an insulating film is provided on a layer of the element and the signal line, a reflective plate serving also as a pixel electrode is newly provided thereon, and both are connected through a contact hole.
[0177]
(Example 37)
Example 37 is a reflection type color liquid crystal device in which a reflection plate is provided between a pair of substrates and only one polarizing plate is disposed, wherein the reflection plate is a specular reflection plate and the outer surface of the substrate located on the incident light side. First, six examples of a reflection type monochrome liquid crystal device will be introduced. All of these can be used as a reflective color liquid crystal device by adding a color filter.
[0178]
<First example>
FIG. 59 is a cross-sectional view of the reflection type liquid crystal device in the first example. First, the configuration will be described. 5901 is a scattering plate, 5902 is an upper polarizing plate, 5903 is an upper substrate, 5904 is an upper electrode, 5905 is a liquid crystal, 5906 is a lower electrode, 5907 is a lower substrate, 5908 is a lower polarizing plate, and 5909 is a specular reflector. is there. The liquid crystal 5905 is twisted 90 degrees in the cell, and is in a TN mode in which the absorption axes of the polarizing plates 5902 and 5908 coincide with the slow axis of the liquid crystal 5 at the close interface. The product Δn × d of the thickness d of the liquid crystal 5905 and the birefringence Δn is 0.48 μm.
[0179]
The reflective liquid crystal device having the above configuration has a brightness of 25% and a contrast of 1:15 in the room in the normal direction of the substrate in the room normal direction, and the brightness of the white display in the regular reflection direction of the ceiling light. Was 45% and the contrast was 1:12. Even in the regular reflection direction, the ceiling light is not reflected due to the back scattering effect of the scattering plate, and a high contrast can be obtained. Since light in the regular reflection direction can be effectively used while maintaining sufficient contrast in this way, a very bright display can be obtained.
[0180]
<Second example>
FIG. 60 shows a reflective liquid crystal device No. 2 in the second example. No. 1 to No. 3 is a sectional view of FIG. Reference numeral 6001 denotes a scattering plate, 6002 denotes an upper polarizing plate, 6003 denotes an upper substrate, 6004 denotes an upper electrode, 6005 denotes a liquid crystal, 6006 denotes a lower electrode, 6007 denotes a lower substrate, and 6008 denotes a specular reflector.
[0181]
FIG. 61 shows the reflective liquid crystal device No. 2 in the second example. No. 1 to No. 3 shows an axial direction of a polarizing plate and the like. 6101 is a transmission axis direction of the upper polarizing plate 6002, 6103 is a rubbing direction of the upper substrate 6003, 6103 is a rubbing direction of the lower substrate 6007, and 6104 is an angle θ1 formed with the horizontal of the transmission axis direction 6101 of the upper polarizing plate 6002, Reference numeral 6105 denotes an angle θ2 between the horizontal direction of the rubbing direction 6102 of the upper substrate 6003, and reference numeral 6106 denotes an angle θ3 between the horizontal direction of the rubbing direction 6103 of the lower substrate 6007. The angle is positive in a counterclockwise direction and is shown from -180 to 180 degrees.
[0182]
FIG. 62 shows the reflective liquid crystal device No. 2 in the second example. 4 to No. 4 6 is a sectional view of FIG. 6201 is a scattering plate, 6202 is an upper polarizing plate, 6203 is a phase difference plate, 6204 is an upper substrate, 6205 is an upper electrode, 6206 is a liquid crystal, 6207 is a lower electrode, 6208 is a lower substrate, and 6209 is a specular reflector. .
[0183]
FIG. 63 shows the reflective liquid crystal device No. 2 in the second example. 4 to No. 4 6 shows an axial direction of a polarizing plate 6 and the like. 6301 is the transmission axis direction of the upper polarizing plate 6202, 6302 is the slow axis direction of the phase difference plate 6203, 6303 is the rubbing direction of the upper substrate 6204, 6304 is the rubbing direction of the lower substrate 6208, and 6305 is the upper polarizing plate 6202. The angle θ1, 6306 between the horizontal of the transmission axis direction 6301 and the angle θ2, 6302 between the horizontal of the rubbing direction 6303 of the upper substrate 6204, and the angle θ3, 6308, the angle θ3, 6308 between the horizontal of the rubbing direction 6304 of the lower substrate 6208 6203 is the angle θ4 formed with the horizontal in the slow axis direction 6302.
[0184]
Table 4 below shows these angle conditions, Δn × d of the liquid crystal cell, and the value of the phase difference of the phase difference plate. In the figure, the unit of Δn × d and the phase difference is μm.
[Table 4]

[0185]
These properties are shown in Table 5 below.
[Table 5]

As in the first example, sufficient contrast and bright display can be obtained.
[0186]
<Comparative Example of First Example and Second Example>
FIG. 64 shows a cross-sectional view of a reflective liquid crystal device according to a comparative example. 6401 is an upper polarizing plate, 6402 is an upper substrate, 6403 is an upper electrode, 6404 is a liquid crystal, 6405 is a lower electrode, 6406 is a lower substrate, 6407 is a lower polarizing plate, and 6408 is a scattering reflector. The liquid crystal 6404 is twisted at 90 degrees in the cell as in the first example, and the absorption axes of the polarizing plates 6401 and 6407 are in the TN mode in which the slow axis of the liquid crystal 5 at the close interface is coincident. The product Δn × d of the thickness d of the liquid crystal 6404 and the birefringence Δn is 0.48 μm.
[0187]
In the reflective liquid crystal device having the above-described configuration, the brightness at the time of white display in the normal direction of the substrate is 28% and the contrast is 1:15 in the room, but the ceiling light is reflected in the regular reflection direction of the ceiling light. For this reason, the brightness of white display was 62% and the contrast was 1: 2, which was not practical.
[0188]
<Third example>
FIG. 65 is a diagram showing characteristics of the scattering plate of the reflection type liquid crystal device in the third example. In FIG. 65, reference numeral 6501 denotes a scattering plate, 6502 denotes incident light, 6503 denotes specular reflection light, and 6504 denotes a 10-degree cone centered on the specular reflection light 6503. The scattering plate 6501 of the third example scatters 5% of the incident light into the 10 ° cone 6503.
[0189]
As described in IEICE technical report EID95-146, a scattering plate with the above characteristics creates forward scattering by mixing particles having a different refractive index from the medium, and adjusts backward scattering by providing minute irregularities on the surface. I got it. If the scattered light is larger than 10%, the reflection of the light source becomes large and the contrast is lowered, and if it is smaller than 0.5%, the display blur becomes too large.
[0190]
The configuration of this embodiment is the same as the configuration of the first embodiment shown in FIG. 59. The liquid crystal 5905 is twisted at 90 degrees in the cell, and the absorption axes of the polarizing plates 5902 and 5908 are close to each other. This is a TN mode that matches the slow axis of the liquid crystal 5905. The product Δn × d of the thickness d of the liquid crystal 5905 and the birefringence Δn is 0.48 μm.
[0191]
The reflective liquid crystal device having the above configuration has a brightness of 26% and a contrast of 1:15 in a room when the white display is performed in the normal direction of the substrate, and the brightness of the white display in the regular reflection direction of the ceiling light. Was 43% and the contrast was 1:13.
[0192]
<Fourth example>
The scattering plate shown in FIG. 65 of the third example was applied to the configurations of FIGS. 60 and 62 of the second example.
[0193]
Each axis direction, Δn × d and phase difference of the liquid crystal shown in FIGS. 61 and 63 were set in the same manner as in the second example. The properties are shown in Table 6 below.
[Table 6]

As in the first embodiment, a sufficient contrast and bright display can be obtained.
[0194]
<Fifth example>
FIG. 66 is a sectional view of a reflective liquid crystal device in the fifth example. First, the configuration will be described. 6601 is a scattering plate, 6602 is an upper polarizing plate, 6603 is an upper substrate, 6604 is an upper electrode, 6605 is a liquid crystal, 6606 is a lower polarizing plate, 6607 is a lower electrode / mirror reflector, and 6608 is a lower substrate. The liquid crystal 6605 is twisted by 90 degrees in the cell, and is in a TN mode in which the absorption axes of the polarizing plates 6602 and 6606 coincide with the slow axis of the liquid crystal 5 at the adjacent interface. The product Δn × d of the thickness d of the liquid crystal 6605 and the birefringence Δn is 0.48 μm. Aluminum was deposited on the lower electrode, and the polarizing plate was obtained by applying and orienting a solution of a liquid crystalline polymer containing a black dichroic dye on a polyimide alignment film. The same scattering plate as in the third example was used.
[0195]
In the reflective liquid crystal device having the above configuration, the brightness at the time of white display in the room normal direction is 28%, the contrast is 1:18, and the brightness of the white display in the regular reflection direction of the ceiling light is indoors. 44%, contrast was 1:16.
[0196]
<Sixth example>
FIG. 67 shows the reflective liquid crystal device No. 6 in the sixth example. No. 1 to No. 3 is a sectional view of FIG. 6701 is a scattering plate, 6702 is an upper polarizing plate, 6703 is an upper substrate, 6704 is an upper electrode, 6705 is a liquid crystal, 6706 is a lower electrode / mirror reflector, and 6707 is a lower substrate.
[0197]
FIG. 61 shows the reflective liquid crystal device No. 6 in the sixth example. No. 1 to No. 3 shows an axial direction of a polarizing plate and the like. 6101 is a transmission axis direction of the upper polarizing plate 6002, 6103 is a rubbing direction of the upper substrate 6003, 6103 is a rubbing direction of the lower substrate 6007, and 6104 is an angle θ1 formed with the horizontal of the transmission axis direction 6101 of the upper polarizing plate 6002, Reference numeral 6105 denotes an angle θ2 between the horizontal direction of the rubbing direction 6102 of the upper substrate 6003, and reference numeral 6106 denotes an angle θ3 between the horizontal direction of the rubbing direction 6103 of the lower substrate 6007.
[0198]
FIG. 68 shows the reflective liquid crystal device No. 6 in the sixth example. 4 to No. 4 6 is a sectional view of FIG. Reference numeral 6801 denotes a scattering plate, 6802 denotes an upper polarizing plate, 6803 denotes a phase difference plate, 6804 an upper electrode, 6805 denotes an upper electrode, 6806 denotes a liquid crystal, 6807 denotes a lower electrode / mirror reflector, and 6808 denotes a lower substrate.
[0199]
FIG. 63 shows the reflective liquid crystal device No. 6 in the sixth example. 4 to No. 4 6 shows an axial direction of a polarizing plate 6 and the like. 6301 is the transmission axis direction of the upper polarizing plate 6202, 6302 is the slow axis direction of the phase difference plate 6203, 6303 is the rubbing direction of the upper substrate 6204, 6304 is the rubbing direction of the lower substrate 6208, and 6305 is the upper polarizing plate 6202. The angle θ1, 6306 between the horizontal of the transmission axis direction 6301 and the angle θ2, 6302 between the horizontal of the rubbing direction 6303 of the upper substrate 6204, and the angle θ3, 6308, the angle θ3, 6308 between the horizontal of the rubbing direction 6304 of the lower substrate 6208 6203 is the angle θ4 formed with the horizontal in the slow axis direction 6302.
[0200]
The conditions of the angle, Δn × d of the liquid crystal, and the phase difference of the retardation plate are the same as those in Table 4 shown in the second example. The same scattering plate as in the third example was used.
[0201]
Table 7 below shows the characteristics of the reflective liquid crystal display device having the above configuration.
[Table 7]

In each case, a sufficient contrast and a bright display can be obtained.
[0202]
Each of the six reflection type monochrome liquid crystal devices described above can be used as a reflection type color liquid crystal device by adding a color filter.
[0203]
FIG. 69 is a diagram showing a main part of a reflective color liquid crystal device according to a working example 37 of the invention. 6901 is a scattering plate, 6902 is an upper polarizing plate, 6903 is a phase plate, 6904 is an upper substrate, 6905 is a liquid crystal, 6906 is a lower substrate, 6907 is a counter electrode (scanning line), 6908 is a signal line, and 6909 is a pixel electrode. A mirror reflector 6910 is an MIM element, and 6911 is a color filter. The distance between pixels was set to 160 μm in both directions perpendicular to and parallel to the signal line, the width of the signal line was set to 10 μm, the gap between the signal line and the pixel electrode was set to 10 μm, and the distance between adjacent pixel electrodes was set to 10 μm.
[0204]
FIG. 63 shows the axial direction of the polarizing plate and the like. 6301 is the transmission axis direction of the upper polarizing plate 6202, 6302 is the slow axis direction of the phase difference plate 6203, 6303 is the rubbing direction of the upper substrate 6204, 6304 is the rubbing direction of the lower substrate 6208, and 6305 is the upper polarizing plate 6202. The angle θ1, 6306 between the horizontal of the transmission axis direction 6301 and the angle θ2, 6302 between the horizontal of the rubbing direction 6303 of the upper substrate 6204, and the angle θ3, 6308, the angle θ3, 6308 between the horizontal of the rubbing direction 6304 of the lower substrate 6208 6203 is the angle θ4 formed with the horizontal in the slow axis direction 6302.
[0205]
The Δn × d of the liquid crystal 6905 is set to 0.33 μm, θ1 is set to −82 degrees, θ2 is set to −74 degrees, θ3 is set to 74 degrees, θ4 is set to 9 degrees, and the phase difference of the phase difference plate 6903 is set to 0.31 μm. The alignment treatment was performed on the line 6908 in the same manner as on the pixel electrode / mirror reflector 6909.
[0206]
The same scattering plate as in the third example was used. As the color filter 6911, a cyan (C in the figure) and red (R in the figure) color filters having an average transmittance of 75% were used.
[0207]
The reflective liquid crystal device having the above configuration has a brightness of 30% and a contrast of 1:15 in white light in the room normal direction in the room, and the brightness of white display in the specular reflection direction of the ceiling light. Was 51% and the contrast was 1:12. In each case, the display colors were x = 0.39 and y = 0.32 for red, x = 0.28 and y = 0.31 for cyan. The color can be recognized sufficiently and the display is bright.
[0208]
(Example 38)
The thirty-eighth embodiment is a reflective color liquid crystal device characterized in that a reflector is provided between a pair of substrates and only one polarizing plate is provided, or the reflector is a specular reflector and the incident light is In the reflective color liquid crystal device, characterized in that a scattering plate is provided on the outer surface of the substrate located on the side, the liquid crystal on the metal wiring is related to the reflective color liquid crystal device in the same orientation as the liquid crystal in the pixel portion. First, two examples related to the reflection type monochrome liquid crystal device will be introduced. All of these can be used as a reflective color liquid crystal device by adding a color filter.
[0209]
<First example>
FIG. 70 is a diagram showing a main part of the reflection type liquid crystal device in the first example. 7001 is a scattering plate, 7002 is an upper polarizing plate, 7003 is an upper substrate, 7004 is a liquid crystal, 7005 is a lower substrate, 7006 is a lower polarizing plate, 7007 is a mirror reflector, 7008 is a counter electrode (scanning line), and 7009 is A signal line, 7010 is a pixel electrode, and 7011 is an MIM element. The liquid crystal 7004 is twisted by 90 degrees in the cell, and is in a TN mode in which the absorption axes of the polarizing plates 7002 and 7006 coincide with the slow axis of the liquid crystal 7004 at the close interface. The product Δn × d of the thickness d of the liquid crystal 7004 and the birefringence Δn is 0.48 μm. The same scattering plate as that of the third example of Example 37 was used.
[0210]
The distance between pixels was set to 160 μm in both directions perpendicular to and parallel to the signal line, the width of the signal line was set to 10 μm, the gap between the signal line and the pixel electrode was set to 10 μm, and the distance between adjacent pixel electrodes was set to 10 μm.
[0211]
In the reflective liquid crystal device having the above structure, a region other than the pixel portion on the signal line 7009 and the counter electrode 7008 was subjected to rubbing treatment in the same manner as the region on the pixel electrode 7010 to arrange the liquid crystal. The brightness at the time of white display in the line direction was 23%, and the contrast was 1:14. The brightness of the white display in the regular reflection direction of the ceiling light was 43%, and the contrast was 1:11.
[0212]
By the way, since the wettability on the metal electrode is different from that of the ITO of the pixel electrode, it is often repelled even if an alignment film is applied. In such a case, that is, when the alignment process is not performed on the signal line 7009, the brightness at the time of white display in the normal direction of the substrate in the room is 19%, the contrast is 1:14, and the regular reflection direction of the ceiling light is used. Was 40% bright and the contrast was 1:11.
[0213]
In each case, a high contrast and a very bright display could be obtained, but a brighter display could be obtained by performing the alignment treatment on the metal wiring.
[0214]
<Second example>
FIG. 71 shows a reflective liquid crystal device No. 2 in the second example. 1 and No. FIG. 3 is a diagram showing a main part of No. 3; 7101 is a scattering plate, 7102 is an upper polarizing plate, 7103 is an upper substrate, 7104 is a liquid crystal, 7105 is a lower substrate, 7106 is a mirror reflector, 7107 is a counter electrode (scanning line), 7108 is a signal line, and 7109 is a pixel electrode. , 7110 are MIM elements. The distance between pixels was set to 160 μm in both directions perpendicular to and parallel to the signal line, the width of the signal line was set to 10 μm, the gap between the signal line and the pixel electrode was set to 10 μm, and the distance between adjacent pixel electrodes was set to 10 μm.
[0215]
FIG. 61 shows the reflective liquid crystal device No. 2 in the second example. No. 1 to No. 3 shows an axial direction of a polarizing plate and the like. 6101 is a transmission axis direction of the upper polarizing plate 6002, 6103 is a rubbing direction of the upper substrate 6003, 6103 is a rubbing direction of the lower substrate 6007, and 6104 is an angle θ1 formed with the horizontal of the transmission axis direction 6101 of the upper polarizing plate 6002, Reference numeral 6105 denotes an angle θ2 between the horizontal direction of the rubbing direction 6102 of the upper substrate 6003, and reference numeral 6106 denotes an angle θ3 between the horizontal direction of the rubbing direction 6103 of the lower substrate 6007.
[0216]
FIG. 72 shows the reflective liquid crystal device No. 2 in the second example. 2 and No. FIG. 4 is a diagram showing a main part of FIG. 7201 is a scattering plate, 7202 is a phase difference plate, 7203 is an upper polarizing plate, 7204 is an upper substrate, 7205 is a liquid crystal, 7206 is a lower substrate, 7207 is a mirror reflector, 7208 is a counter electrode (scanning line), and 7209 is a signal. A line, 7210 is a pixel electrode, and 7211 is an MIM element. The distance between pixels was set to 160 μm in both directions perpendicular to and parallel to the signal line, the width of the signal line was set to 10 μm, the gap between the signal line and the pixel electrode was set to 10 μm, and the distance between adjacent pixel electrodes was set to 10 μm.
[0219]
FIG. 63 shows the reflective liquid crystal device No. 2 in the second example. 4 to No. 4 6 shows an axial direction of a polarizing plate 6 and the like. 6301 is the transmission axis direction of the upper polarizing plate 6202, 6302 is the slow axis direction of the phase difference plate 6203, 6303 is the rubbing direction of the upper substrate 6204, 6304 is the rubbing direction of the lower substrate 6208, and 6305 is the upper polarizing plate 6202. The angle θ1, 6306 between the horizontal of the transmission axis direction 6301 and the angle θ2, 6302 between the horizontal of the rubbing direction 6303 of the upper substrate 6204, and the angle θ3, 6308, the angle θ3, 6308 between the horizontal of the rubbing direction 6304 of the lower substrate 6208 6203 is the angle θ4 formed with the horizontal in the slow axis direction 6302.
[0218]
The same scattering plate as that of the third example of Example 37 was used.
In the reflection type liquid crystal device having the above configuration, 1 and No. No. 2 is obtained by subjecting an area other than the pixel portion to an alignment process. 3 and No. In No. 4, only the pixel portion was subjected to an alignment treatment.
[0219]
Table 8 below shows Δn × d of the liquid crystal 7205, angles of the polarizing plates and the like, and phase differences of the retardation plates.
[Table 8]

[0220]
The characteristics are shown in Table 9 below.
[Table 9]

[0221]
In each case, a bright display with high contrast can be obtained. However, a brighter display can be obtained by performing the alignment treatment on the region other than the pixel portion.
[0222]
(Example 39)
Embodiment 39 relates to a reflective color liquid crystal device whose display is a normally white type. First, an example relating to a reflective monochrome liquid crystal device will be introduced. This can be used as a reflective color liquid crystal device by adding a color filter.
[0223]
FIG. 59 shows the reflective liquid crystal device No. 39 of Example 39. 1, No. 2 is a sectional view of FIG. First, the configuration will be described. 5901 is a scattering plate, 5902 is an upper polarizing plate, 5903 is an upper substrate, 5904 is an upper electrode, 5905 is a liquid crystal, 5906 is a lower electrode, 5907 is a lower substrate, 5908 is a lower polarizing plate, and 5909 is a specular reflector. is there. The liquid crystal 5905 is twisted by 90 degrees in the cell. No. 1 coincides with the slow axis of the liquid crystal 5905 at the interface where the absorption axes of the polarizing plates 5902 and 5908 are close to each other. Reference numeral 2 denotes a TN mode in which the absorption axis of the polarizing plate 5902 and the absorption axis of 5908 coincide with the slow axis of the liquid crystal 5905 at the interface where the absorption axes are close to each other. The product Δn × d of the thickness d of the liquid crystal 5905 and the birefringence Δn is 0.48 μm.
The same scattering plate as that of the third example of Example 37 was used.
[0224]
FIG. 73 is a diagram showing a voltage transmittance characteristic of the reflection type liquid crystal device of Example 37. Here, 7301 is No. 7 shows how the transmittance changes with respect to the voltage of No. 1; 7 shows how the transmittance changes with respect to a voltage of 2. No. 1 is normally white, No. 1 2 is a normally black display.
[0225]
The reflective liquid crystal device having the above-described configuration is the same as that of No. Reference numeral 1 indicates that in a room, the brightness of white display in the normal direction of the substrate is 25% and the contrast is 1:15, the brightness of white display in the regular reflection direction of the ceiling light is 45%, and the contrast is 1: It was 12. No. In the room 2, the brightness of white display in the normal direction of the substrate is 23% and the contrast is 1:15, and the brightness of white display in the specular reflection direction of the ceiling light is 42% and the contrast is 1: It was 13.
[0226]
In both cases, sufficient contrast and bright display can be obtained, but a brighter display can be obtained in the normally white mode. This is because the area outside the pixel contributes to the brightness and because it has a viewing angle characteristic in which light incident from an oblique direction is easily transmitted.
[0227]
(Example 40)
When the display is performed by the reflection type color liquid crystal devices in the above-described embodiments 1 to 39, a problem occurs that does not exist in the conventional transmission type color liquid crystal device. That is, a single dot does not sufficiently generate color, and the same color needs to be displayed over a certain wide area in order to display a color. This is because the color of the color filter is pale, the distance between the liquid crystal layer and the reflection plate is large (excluding Examples 36 to 39), and the colors of adjacent dots are easily mixed.
[0228]
Therefore, a method of displaying black characters on a white background and making a part of the background red, that is, a method of using a marker, is more suitable than a method of displaying red characters on a white background. However, the fact that a single pixel does not produce sufficient color also means that a monochrome display can be easily performed in spite of being a color liquid crystal device.
[0229]
The reflective color liquid crystal device of the embodiment 40 is characterized in that one pixel is constituted by one dot. A pixel is a minimum unit capable of realizing a function necessary for display. In a normal color liquid crystal device, one pixel is composed of a total of three dots each for red, green and blue. Therefore, 480 × 640 × 3 dots were required to perform VGA display of 480 × 640 pixels. When using two color filters of cyan and red, 480 × 640 × 2 dots were required. However, Embodiment 40 can perform VGA display with 480 × 640 pixels while being a color liquid crystal device.
[0230]
The configuration of the working example 40 is the same as, for example, the working example 5 and the like. However, in the case of displaying, the following measures are taken. An example is shown in FIG. 74, and description will be made with reference to this figure. Here, 16 × 48 pixels are shown. (A) is a diagram showing an arrangement of color filters, in which red (indicated by “R”) and cyan (indicated by “C”) are arranged in a mosaic pattern. (B) and (c) are diagrams showing distributions of on dots and off dots. On-dots are indicated by hatching because they are dark displays. The display in (b) is a display which is turned on in the form of "LCD" ignoring the color filter array. However, as described above, this reflective type color liquid crystal device does not sufficiently develop color with a single dot. "LCD" appears black on a white background. Therefore, monochrome display can be performed at the resolution of VGA. On the other hand, the display of (c) is a display in which only the cyan dots in the background of (b) are turned on, and it appears that "LCD" is displayed in black in red. When the same color is displayed over an area of 10 dots or more, the color can be displayed.
[0231]
In addition to the use as a marker, for example, when displaying map information, it is possible to color only a specific route if the road width is several dots. Further, since icons and the like on the personal computer screen have a certain area, they can be displayed in color.
[0232]
(Example 41)
The reflective color liquid crystal devices in Examples 1 to 40 described above were employed as displays of electronic equipment.
[0233]
FIG. 75 is a diagram illustrating an example of an electronic apparatus that employs the reflective color liquid crystal devices according to the first to forty embodiments. This is a so-called PDA (Personal Digital Assistant), which is a type of portable information terminal. Reference numeral 7501 denotes a reflective color liquid crystal device, on which a tablet for pen input is mounted. Conventionally, a reflection type monochrome liquid crystal device or a transmission type color liquid crystal device has been used for a PDA display. By replacing these with a reflective type color liquid crystal device, there is an advantage that the amount of information is greatly increased by color display as compared with the former, and there is an advantage that the battery life is longer and the size and weight are reduced as compared with the latter.
[0234]
FIG. 76 is a diagram illustrating an example of the electronic device according to the forty-first embodiment in which the display unit is attached to the main body so that ambient light can be efficiently reflected to an observer. This is a so-called digital still camera. Reference numeral 7601 denotes a reflective color liquid crystal device, which is mounted so that its angle with respect to the main body can be changed. Although not shown, the lens is located on the back side of the reflection type color liquid crystal device mounting portion. Conventionally, transmission type color liquid crystal devices have been used for displays for digital still cameras. By replacing this with a reflective type color liquid crystal device, not only the battery life is prolonged and the size is reduced, but also the visibility under direct sunlight is remarkably improved. This is because the transmissive color liquid crystal device has a limited brightness of the backlight, so that it becomes difficult to see when the surface reflection increases in direct sunlight, but the reflective color liquid crystal device becomes brighter as the ambient light becomes brighter. It is. In order to effectively use this ambient light, it is effective to mount the liquid crystal device so that the angle of the liquid crystal device can be changed.
[0235]
In addition to the above electronic devices, reflective color liquid crystal devices include various devices that emphasize portability such as palmtop PCs, subnotebook PCs, notebook PCs, handy terminals, camcorders, LCD TVs, game machines, electronic organizers, mobile phones, and pagers. Applicable to electronic equipment.
[Brief description of the drawings]
FIG. 1 is a diagram showing a main part of the structure of a reflective type color liquid crystal device in Examples 1 to 4, 27, 29, and 33 of the present invention.
FIG. 2 is a diagram illustrating spectral characteristics of a color filter of a reflective color liquid crystal device according to the first embodiment of the present invention.
FIG. 3 is a diagram illustrating spectral characteristics of color filters of a reflective color liquid crystal device in Examples 2, 3, 5, 23, 29, 31, 32, 34, 36, and 40 of the present invention.
FIG. 4 is a diagram plotting a change in contrast when the thickness of an element substrate is changed in a reflective color liquid crystal device according to a third embodiment of the present invention.
FIG. 5 is a diagram illustrating spectral characteristics of a color filter of a reflective color liquid crystal device according to a fourth embodiment of the present invention.
FIG. 6 is a diagram showing a main part of the structure of a reflective type color liquid crystal device in Examples 5, 6, 23, 27, 32, and 40 of the present invention.
FIG. 7 is a diagram illustrating spectral characteristics of a color filter of a reflective color liquid crystal device according to a sixth embodiment of the present invention.
FIG. 8 is a diagram showing a main part of the structure of a reflective type color liquid crystal device in Examples 7, 9, 24, 27, and 28 of the present invention.
FIG. 9 is a diagram illustrating spectral characteristics of a color filter of a reflective color liquid crystal device according to a seventh embodiment of the present invention.
FIG. 10 is a diagram showing a main part of the structure of a reflective color liquid crystal device according to Embodiments 8 and 10 of the present invention.
FIG. 11 is a diagram illustrating spectral characteristics of a color filter of a reflective color liquid crystal device according to an eighth embodiment of the present invention.
FIG. 12 is a diagram showing the spectral characteristics of the color filters of the reflective color liquid crystal device in Examples 9, 24, 25, and 26 of the present invention.
FIG. 13 is a diagram illustrating spectral characteristics of a color filter of a reflective color liquid crystal device according to a tenth embodiment of the present invention.
FIG. 14 is a diagram plotting changes in average transmittance when the thickness of a color filter is changed in a reflective color liquid crystal device according to Example 10 of the present invention.
FIG. 15 is a diagram illustrating a main part of the structure of a reflective color liquid crystal device according to embodiments 11, 12, and 15 of the present invention.
FIG. 16 is a diagram showing the spectral characteristics of the color filters of the reflective color liquid crystal device in Examples 11, 21, and 26 of the present invention.
FIG. 17 is a diagram plotting the change in average transmittance when the ratio of the area where a color filter is provided is changed in the reflective color liquid crystal device according to Example 11 of the present invention.
FIG. 18 is a diagram illustrating spectral characteristics of a color filter of a reflection type color liquid crystal device in Examples 12 and 26 of the present invention.
FIG. 19 is a diagram plotting a change in average transmittance when a ratio of an area where a color filter is provided is changed in a reflective color liquid crystal device according to a twelfth embodiment of the present invention.
FIG. 20 is a diagram showing a main part of the structure of a reflective color liquid crystal device according to Examples 13 and 15 of the present invention.
FIG. 21 is a diagram showing a main part of the structure of a reflective color liquid crystal device according to Examples 14 and 15 of the present invention.
FIG. 22 is a diagram illustrating a voltage reflectance characteristic of a reflective type color liquid crystal device in Embodiment 15 of the present invention.
FIG. 23 is a diagram illustrating a structure of a color filter substrate of a reflective color liquid crystal device according to Embodiment 16 of the present invention.
FIG. 24 is a diagram showing a main part of the structure of a reflective color liquid crystal device according to Embodiment 16 of the present invention.
FIG. 25 is a diagram illustrating spectral characteristics of a color filter of a reflective color liquid crystal device according to Embodiment 16 of the present invention.
FIG. 26 is a diagram illustrating an average spectral characteristic within one dot of a color filter of a reflection type color liquid crystal device in Examples 16 and 17 of the present invention.
FIG. 27 is a diagram showing a structure of a color filter substrate of a reflective color liquid crystal device in a comparative example referred to in Embodiment 16 of the present invention.
FIG. 28 is a diagram illustrating a structure of a color filter substrate of a reflective color liquid crystal device according to Embodiment 17 of the present invention.
FIG. 29 is a diagram illustrating spectral characteristics of a color filter of a reflection type color liquid crystal device in Embodiment 17 of the present invention.
FIG. 30 is a diagram illustrating spectral characteristics of a color filter of a reflection type color liquid crystal device in Embodiment 17 of the present invention.
FIG. 31 is a diagram illustrating spectral characteristics of a color filter of a reflective color liquid crystal device according to Embodiment 17 of the present invention.
FIG. 32 is a diagram showing an arrangement of a color filter of a reflective color liquid crystal device according to Embodiment 18 of the present invention.
FIG. 33 is a diagram illustrating a main part of the structure of a reflective color liquid crystal device according to a twenty-first embodiment of the present invention.
FIG. 34 is a diagram illustrating an arrangement of color filters of a reflective color liquid crystal device according to a twenty-first embodiment of the present invention.
FIG. 35 is a diagram showing an arrangement of a color filter of a reflection type color liquid crystal device in Embodiment 21 of the present invention.
FIG. 36 is a diagram illustrating an arrangement of a color filter of a reflective color liquid crystal device according to Embodiment 21 of the present invention.
FIG. 37 is a view schematically showing a structure of a reflective type color liquid crystal device in Embodiment 22 of the present invention.
FIG. 38 is a diagram showing an arrangement of a color filter of a reflection type color liquid crystal device in Embodiment 23 of the present invention.
FIG. 39 is a diagram illustrating an arrangement of a color filter of a reflective color liquid crystal device according to Embodiment 24 of the present invention.
FIG. 40 is a diagram illustrating a main part of the structure of a reflective color liquid crystal device according to Embodiment 25 of the present invention.
FIG. 41 is a diagram showing an arrangement of a color filter of a reflection type color liquid crystal device in Embodiment 25 of the present invention.
FIG. 42 is a diagram showing a main part of the structure of a reflective color liquid crystal device according to Embodiment 26 of the present invention.
FIG. 43 is a diagram illustrating a wiring method of an MIM element of a reflection type color liquid crystal device in Example 28 of the present invention.
FIG. 44 is a diagram illustrating a wiring method of an MIM element of a reflective color liquid crystal device in a comparative example referred to in the working example 28 of the invention.
FIG. 45 is a diagram plotting changes in contrast and reflectance when the driving area is changed in the reflective color liquid crystal device according to Example 29 of the present invention.
FIG. 46 is a diagram for explaining the scattering characteristics of the reflector of the reflective color liquid crystal device according to the working example 30 of the invention.
FIG. 47 is a diagram illustrating scattering characteristics of a reflector of a reflective type color liquid crystal device in Example 30 of the present invention.
FIG. 48 is a diagram plotting brightness and contrast ratio when the ratio of light reflected within a 30-degree cone is changed in the reflective color liquid crystal device according to Example 30 of the present invention.
FIG. 49 is a diagram illustrating a main part of the structure of a reflective color liquid crystal device according to a working example 31 of the invention.
FIG. 50 is a diagram showing a relationship between axes of a reflection type color liquid crystal device in Examples 32 and 33 of the present invention.
FIG. 51 is a diagram plotting a change in reflectance of white display when Δn × d of a liquid crystal cell is changed in a reflective color liquid crystal device according to Example 33 of the present invention.
FIG. 52 is a diagram illustrating a main part of the structure of a reflective color liquid crystal device according to Embodiment 34 of the present invention.
FIG. 53 is a diagram illustrating a relationship between axes of a reflective color liquid crystal device according to Examples 34 and 35 of the present invention.
FIG. 54 is a diagram illustrating spectral characteristics of a color filter of a reflective color liquid crystal device according to Example 35 of the present invention.
FIG. 55 is a diagram illustrating a main part of a structure of a reflective color liquid crystal device according to a working example 35 of the invention.
FIG. 56 is a diagram illustrating a main part of a structure of a reflective color liquid crystal device according to a working example 36 of the invention.
FIG. 57 is a diagram illustrating a relationship among axes of a reflective color liquid crystal device according to a working example 36 of the invention.
FIG. 58 is a diagram illustrating a main part of a structure of a reflective color liquid crystal device according to Embodiment 36 of the present invention;
FIG. 59 is a diagram illustrating a main part of a structure of a reflective color liquid crystal device according to Examples 37 and 39 of the present invention.
FIG. 60 is a diagram showing a main part of the structure of a reflective color liquid crystal device according to a working example 37 of the invention.
FIG. 61 is a diagram showing a relationship between axes of a reflective color liquid crystal device in Examples 37 and 38 of the present invention.
FIG. 62 is a diagram showing a main part of the structure of a reflective color liquid crystal device according to a working example 37 of the invention.
FIG. 63 is a diagram showing a relationship between axes of a reflection type color liquid crystal device in Examples 37 and 38 of the present invention.
FIG. 64 is a diagram showing a main part of the structure of a reflective color liquid crystal device according to a working example 37 of the invention.
FIG. 65 is a diagram illustrating characteristics of a scattering plate of a reflective color liquid crystal device according to Example 37 of the present invention.
FIG. 66 is a diagram illustrating a main part of a structure of a reflective color liquid crystal device according to a working example 37 of the invention.
FIG. 67 is a diagram illustrating a main part of the structure of a reflective color liquid crystal device according to a working example 37 of the invention.
FIG. 68 is a diagram illustrating a main part of a structure of a reflective color liquid crystal device according to a working example 37 of the invention.
FIG. 69 is a diagram showing a main part of the structure of a reflective color liquid crystal device according to a working example 37 of the invention.
FIG. 70 is a diagram showing a main part of the structure of a reflective color liquid crystal device according to a working example 38 of the invention.
FIG. 71 is a diagram illustrating a main part of a structure of a reflective color liquid crystal device according to a working example 38 of the invention.
FIG. 72 is a diagram showing a main part of the structure of a reflective color liquid crystal device according to a working example 38 of the invention.
FIG. 73 is a diagram showing a voltage transmittance characteristic of a reflective type color liquid crystal device in Example 39 of the present invention.
FIG. 74 is a diagram illustrating an example of a display method of a reflective type color liquid crystal device in Embodiment 40 of the present invention.
FIG. 75 is a diagram illustrating an example of an electronic apparatus using a reflective color liquid crystal device according to a working example 41 of the invention.
FIG. 76 is a diagram illustrating an example of an electronic apparatus using the reflective color liquid crystal device in Embodiment 41 of the present invention.
FIG. 77 is a diagram for explaining the problem of parallax peculiar to the reflective color liquid crystal device.
FIG. 78 is a diagram illustrating spectral characteristics of a color filter of a conventional transmission type color liquid crystal device.
FIG. 79: Tatsuo Uchida et al. (IEEE Transactions on Electron Devices, Vol. ED-33, No. 8, pp. 1207-1121 (1986)). FIG. 8 is a diagram illustrating spectral characteristics of a color filter proposed in FIG.
FIG. 80: A paper by Seiichi Mitsui et al. (SID92 DIGEST, pp. 437-440 (1992)), FIG. FIG. 3 is a diagram illustrating spectral characteristics of a color filter proposed in No. 2;
FIG. 81 is a diagram showing the spectral characteristics of the color filters proposed in FIGS. 2 (a), (b), and (c) of JP-A-5-241143.
[Explanation of symbols]
1001 Upper polarizing plate, 1002 Element substrate, 1003 Liquid crystal, 1004 Counter substrate, 1005 Lower polarizing plate, 1006 Scattering reflector, 1007 Signal line, 1008 MIM element, 1009 Pixel electrode, 1010 Color filters, 1011: Counter electrode (scanning line).

Claims (3)

In a reflective color liquid crystal device in which a pair of substrates are arranged facing each other and provided with a plurality of color filters,
The plurality of color filters include a red color filter, a blue color filter, and a green color filter,
The red color filter has a wavelength of 570 nm to 660 nm, the blue color filter has a wavelength of 450 nm to 520 nm, and the green color filter has a wavelength of 510 nm to 590 nm. A reflective color liquid crystal device characterized by exhibiting a transmittance of 70% or more for each of light in the range. An electronic apparatus comprising the reflective color liquid crystal device according to claim 1 as a display unit. 3. The electronic device according to claim 2, wherein a display unit of the reflection type color liquid crystal device is mounted to be movable with respect to a main body so that ambient light can be efficiently reflected to an observer. .

Images