JP3606312B2 - Reflective liquid crystal device and electronic apparatus 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】
１０１…上側偏光板、１０２…対向基板、１０３…液晶、１０４…素子基板、１０５…下側偏光板、１０６…散乱反射板、１０７…カラーフィルタ、１０８…対向電極（走査線）、１０９…信号線、１１０…画素電極、１１１…ＭＩＭ素子。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reflective color liquid crystal device and an electronic apparatus using the same.
[0002]
[Prior art]
First of all, a display mounted on a portable information terminal needs to have low power consumption. Therefore, a reflective liquid crystal device that does not require a backlight is optimal for this application. However, the conventional reflection type liquid crystal device is mainly monochrome display, and a good reflection type color display has not been obtained yet.
[0003]
The development of the reflective color liquid crystal device seems to have started in earnest since the mid-1980s. Prior to that, there was only recognition that a reflective color display would be possible if the backlight of a transmissive color liquid crystal device was replaced with a reflector, as disclosed in, for example, Japanese Patent Laid-Open No. 50-80799. However, as you can see when you actually make it, this configuration is too dark to be useful. There are three causes, one is that the polarizing plate throws away more than 1/2 of the light, the second is that more than 2/3 of the light is thrown away by the color filter, and finally the parallax problem It is. The problem of parallax is unavoidable in the TN (twisted nematic) mode and STN (super twisted nematic) mode that are generally used in transmissive liquid crystal devices. This is because in these modes, since two polarizing plates are always used, a non-negligible gap occurs between the reflector and the liquid crystal layer unless a polarizing plate is formed in the cell. Note that the parallax problem mentioned here refers not only to the problem of double reflection of the display that was also present in the conventional reflective type monochrome liquid crystal device, but also to a problem peculiar to the reflective type color liquid crystal device.
[0004]
The parallax problem will be described with reference to the drawings. 77 (a) and 77 (b) are cross-sectional views of a reflective 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 reflection plate 7706, and a red, green and blue three-color filter 7707. Other transparent electrodes, alignment films, insulating films, and the like exist between the upper and lower glass substrates, but they are omitted because they are not necessary for explaining the parallax problem. There are two parallax problems. One is color cancellation. In FIG. 77 (a), an observer 7712 sees reflected light 7711 that has exited through a green filter. This light is incident on light 7713 that has passed through red, green, and blue filters. It is scattered and reflected by the reflector and mixed. If the thickness of the lower glass substrate is sufficiently larger than the pitch of the color filter, light passing through any color filter is mixed with equal probability. However, the light passing through the red → green and blue → green paths is absorbed by any of the color filters and becomes dark, leaving only the light passing through the green → green path. The same can be said for the reflected light coming out through the blue and red filters, which eventually results in a problem that the brightness of the white display becomes 1/3 of that without parallax. Another problem is that the color display becomes dark. FIG. 77 (b) shows a green display state. In addition, a lattice-shaped hatched portion in the liquid crystal layer 7703 indicates that it is in a non-lighting state (dark state). Incident light 7713 passes through red, green, and blue dots with equal probability, but 2/3 of them is absorbed by red and blue dots in the off state. Further, after being scattered and mixed by the light reflector, 2/3 is absorbed again by the red and blue dots in the off state, and reaches the observer 7712. Therefore, the green display becomes “1/9 the brightness of the white display minus the absorption amount of the green filter”, which is very dark. As described above, it is very difficult to use the TN mode or STN mode having a 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 the paper by Tatsuo Uchida et al. (IEEE Transactions on Electron Devices, Vol. ED-33, No. 8, pp. 1207-1212 (1986)), FIG. After comparing the brightness of various liquid crystal modes in No. 2, a PCGH (phase transition guest host) mode that does not require a polarizing plate is adopted. Japanese Patent Laid-Open No. 5-241143 also adopts a PDLC (polymer dispersed liquid crystal) mode that does not require a polarizing plate in order to realize a reflective color liquid crystal device. 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 an 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 that does not require a polarizing plate generally has a low contrast, and the PCGH mode in particular has a problem that a halftone display cannot be performed due to hysteresis of voltage transmittance characteristics. Further, these liquid crystal modes in which another substance is added to the liquid crystal have many problems in terms of reliability. Therefore, it has been widely used in the past, and if a proven TN mode or STN mode can be used, this will not be exceeded.
[0006]
Conventionally, an attempt has been made to obtain a bright reflective color display using a bright color filter. In general, a color filter used in a transmissive color liquid crystal device has spectral characteristics as shown in FIG. The horizontal axis of FIG. 78 is the wavelength of light, 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. The light that can be sensed by humans is generally in the wavelength range of 380 nm to 780 nm, although there are differences among individuals, and particularly has high visibility in the wavelength range of 450 nm to 660 nm. All the color filters in FIG. 78 have a wavelength within which the transmittance is 10% or less, and a lot of light is wasted. Further, when a value obtained by simply averaging the transmittance in this wavelength range is defined as an average transmittance, the average transmittance of the red filter is 28%, the green filter is 33%, and the blue filter is 30%.
[0007]
A brighter color filter is required for use in a reflective color liquid crystal device. Therefore, in the aforementioned paper by Tatsuo Uchida et al., FIG. It has been proposed to use two color filters that are complementary to each other as shown in FIG. The spectral characteristics are shown in FIG. The horizontal axis in 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. Since the vertical axis represents the reflectance, care must be taken in comparison. However, in the wavelength range of 450 nm to 660 nm, there is a wavelength at which the transmittance of each color filter is 10% or less. The average transmittance was 41% for the green filter and 48% for the magenta filter.
[0008]
Also, a paper by Seiichi Mitsui et al. (SID92 DIGEST, pp. 437-440 (1992)) relates to a reflective color liquid crystal device adopting the same PCGH mode. A bright two-color filter as shown in FIG. The spectral characteristics are shown in FIG. In FIG. 80, the horizontal axis represents the light wavelength, the vertical axis represents the reflectance, 8001 represents the spectrum of the green filter, and 8002 represents 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 if such a bright color filter is used.
[0009]
Further, the color filters proposed in FIGS. 2 (a), (b), and (c) of Japanese Patent Laid-Open No. 5-241143 are not red, green, and blue, but yellow, cyan, It is brightened using three colors of magenta. The spectral characteristics are shown in FIG. The horizontal axis in FIG. 81 is the wavelength of light, 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. Although the vertical axis represents the reflectance and the axis is not graduated, it is difficult to compare, but in the wavelength range from 450 nm to 660 nm, all the color filters have a transmittance of 10% or less. There is no doubt that wavelengths exist. When the average transmittance was roughly estimated, the yellow filter was about 0%, the cyan filter was about 60%, and the magenta filter was about 50%.
[0010]
Thus, the conventional efforts to develop a reflective color liquid crystal device are based on the idea of obtaining a bright display by combining a bright liquid crystal mode that does not use a polarizing plate and a bright color filter. However, even if it is a bright color filter, a color filter having a wavelength with a transmittance of less than 10% in a wavelength range of 450 nm to 660 nm is often used.
[0011]
[Problems to be solved by the invention]
It is an object of the present invention to provide a reflective color liquid crystal device capable of displaying a bright image with good contrast, and to provide an electronic device using the same.
[0012]
[Means for Solving the Problems]
The invention according to claim 1 has a pair of substrates provided with electrodes on opposite inner surfaces and formed with a matrix-like dot group, and a plurality of color filters having different colors, and one of the pair of substrates. In a reflective color liquid crystal device having a reflective layer disposed on a substrate, each of the plurality of color filters having different colors is provided only in a part of a region to be reflected and displayed by light modulation in each dot. And the area ratio of the color filter with respect to the region is 15% or more, the reflection layer is a scattering reflection layer, and 80% or more of the light reflected by the scattering reflection layer is 30 ° cone It is included in the inside.
[0013]
According to a second aspect of the present invention, in the electronic apparatus, the reflective color liquid crystal device according to the first aspect is provided 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 the observer. It is characterized by that.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The outline of the present invention will be described. The present invention comprises a pair of substrates having electrodes on the inner surfaces facing each other to form a matrix-like dot group, a liquid crystal sandwiched between the substrates, a color filter of at least two colors, at least one polarizing plate, It can be set as the structure which has a reflecting plate. 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]
Moreover, the thickness of the board | substrate located in the reflecting plate side among said pair of board | substrates can be 200 micrometers or more. More preferably, the thickness of the substrate located on the reflecting plate side can be set to 700 μm or more. In other words, the thickness of the substrate located on the reflecting plate side can be 1.25 times or more, more preferably 4 times or more of the shorter one of the vertical and horizontal dot pitches. With this configuration, there is an advantage that high contrast can be secured due to the parallax effect even if the drive area ratio is small.
[0017]
Conventionally, for example, Japanese Patent Publication No. 3-64850 has proposed that the thickness of the lower substrate of the reflective monochrome liquid crystal device is 300 μm or less. Certainly, in the reflective monochrome display, the lower substrate should be as thin as possible from the viewpoint of reducing double images (shadows). However, in the reflection type color display, it is desired to widen the space between dots from the viewpoint of brightening the color display. If the space between the dots is wide, the contrast is inevitably lowered. However, if the lower substrate is sufficiently thick, high contrast can be secured due to the shadow effect of adjacent pixels.
[0018]
In addition, at least one color filter among the color filters may have a transmittance of 50% or more for light of all wavelengths in the range of 450 nm to 660 nm. More preferably, the color filters of at least two colors 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 color filter 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 may 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 color filter can have an average transmittance of 70% or more for light having a wavelength in the range of 450 nm to 660 nm. More preferably, any color filter can have an average transmittance of 75% or more and 90% or less with respect to light having a wavelength in the range of 450 nm to 660 nm.
[0019]
The transmittance of the color filter referred to here is the transmittance of a single color filter that does not include the transmittance of the glass substrate, the transparent electrode, the overcoat, and the undercoat. When there is a distribution in the density of the color filter, or when a color filter is provided only for a part of the dots, the average transmittance in the dots is used 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 Laid-Open No. 7-239469, the transmittance of the light transmission region is 80% or more and the transmittance of the light absorption region is 50% or less in any color filter. Moreover, even if it sees the Example, the transmittance | permeability of a light absorption area | region is only 20-30%. In such a color filter, when a liquid crystal mode using a polarizing plate is used, the display becomes dark and is not practical.
[0020]
The color filter may be composed of three colors of red, green, and blue, and any one of the red or blue color filters may be orange or cyan. However, the orange filter can have a transmittance of 70% or more, preferably 75% or more with respect to light having a wavelength in the range of 570 nm to 660 nm. The cyan filter has a transmittance of at least 70%, preferably at least 75% with respect to light having a wavelength in the range of 450 nm to 520 nm. With this configuration, the reflective color liquid crystal device has an advantage that bright white and bright colors can be displayed.
[0021]
The color filter is composed of three colors of red, green, and blue, and the minimum transmittance for light having a wavelength in the range of 450 nm to 660 nm of the red color filter is blue or green. It is characterized in that it is smaller than the minimum transmittance of light having a wavelength in the range of 450 nm to 660 nm of the color filter of the filter. 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 this configuration, the reflective color liquid crystal device has an advantage that it can display bright white with little color and can also display bright red. Since red is the color stimulus that most appeals to the human eye, it is very preferable to display it with emphasis on red.
[0022]
Further, the color filter is provided only in a part of the light-modulable region in each dot. With such a configuration, the reflective color liquid crystal device of the present invention has the advantages that the conventional color filter manufacturing technique can be used and color mixing due to parallax is reduced. In particular, when the 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 the color purity in a halftone is improved. Conventionally, for example, Japanese Patent Publication No. 7-62723 proposes to provide a color filter on a part of a dot, but this is a transmission type liquid crystal device and is limited to a dyeing method color filter. It differs from the present invention in that the area where the filter is provided is as large as 67% to 91% of the dots. (The expression of Japanese Examined Patent Publication No. 7-62723 is 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 almost the same thickness as the color filter in a region where the color filter is not provided in the light-modulable region and a region where the light modulation is impossible. With such a configuration, the reflective color liquid crystal device has an advantage that a high-quality display can be performed without disturbing liquid crystal alignment.
[0024]
Further, the color filter is provided only for the number of dots that is three quarters or less of the total number of dots. More preferably, it is provided only for the number of dots that is two-thirds or less of the total number of dots. With this configuration, bright display is possible, and even when halftone color display is performed, if brightness is adjusted mainly with dots that do not have a color filter, there is an advantage that vivid colors 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 this has never been proposed for a reflective liquid crystal device. In particular, in the reflective color liquid crystal device using the TN mode or the STN mode, the parallax problem is unavoidable, and it becomes very dark when color display is performed. However, by providing dots without a color filter, a bright color display is achieved. 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, the stripe arrangement does not fall within this range. This configuration has an advantage of alleviating the phenomenon that the degree of coloring varies depending on the viewing angle, particularly when there is parallax. Conventionally, for example, in JP-A-8-87009, a vertical stripe arrangement is recommended in claim 6. Japanese Patent Laid-Open No. 5-241143 states that there is no difference in principle between the stripe arrangement and the zigzag arrangement in the 17th to 18th lines of the right column on page 6 of the specification. Also, in the paper by Tatsuo Uchida et al. (IEEE Transactions on Electron Devices, Vol. ED-33, No. 8, pp. 1207-1212 (1986)). In No. 1, a mosaic arrangement color filter is employed, but this is a case where a reflective electrode is provided in the 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. With this configuration, there is an advantage that the display looks bright. The “effective display area” is defined as “a drive display area and an area effective as a screen subsequent thereto” in ED-2511A of the Japan Electronic Machinery Manufacturers Association (EIAJ) standard. Usually, in transmissive color display, a color filter is provided only in the drive display area, and a black mask made of metal or resin is provided in the outer area. However, in the reflective color display, the metal black mask is glaring and cannot be used. In addition, the resin black mask increases the cost because the original color filter is not provided with a black mask. However, if nothing is provided outside the drive display area, the outside becomes bright and the drive display area looks relatively dark. Therefore, it is effective to provide the same color filter on the outside of the drive display area as that on the inside, preferably in the same pattern.
[0027]
In addition, a black mask is not provided in the area outside each dot, but instead, a color filter having an absorption comparable to or smaller than the area in the dot can be provided. This configuration basically means that no black mask or color filter overlaps outside the dots. In addition, nothing is provided outside the dots, which means that some or all of the color filters are provided. This configuration has an advantage that a bright display can be obtained. This is because, particularly when there is parallax, the brightness of the display is proportional to the square of the aperture ratio, so it is very dark when a black mask is provided. Conversely, no color filter is provided outside the dots. This is because the contrast is significantly lowered. Conventionally, for example, in Japanese Patent Application Laid-Open No. 59-198489, a color filter is provided only on the pixel electrode, and nothing is provided outside the color filter. Japanese Patent Application Laid-Open No. 5-241143 describes both the case where there is a black mask and the case where there is no black mask.
[0028]
Moreover, a color filter can be provided on the outer surface of the substrate located on the reflector side of the pair of substrates. This configuration has an advantage that it can be provided at a low cost. Further, by combining this configuration with a configuration in which the color filter is provided only in a part of the light-modulable region in each dot, there is an advantage that the assembly margin is expanded and the viewing angle is widened.
[0029]
Moreover, a nonlinear element can be provided corresponding to each dot on the inner surface of the substrate located on the reflector side of the pair of substrates. This configuration has the advantage that unnecessary surface reflection is reduced and high contrast can be obtained.
[0030]
Further, a non-linear element may be provided corresponding to 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 PC use, the dot is often vertically long, and the direction parallel to the short side of the dot is the horizontal direction (horizontal direction). This configuration has the advantage that the aperture ratio is increased and bright display can be obtained. This is particularly effective when a black mask is not provided and when the reflection type configuration has parallax.
[0031]
Further, the drive area ratio can be set to 60% to 85%. Here, the drive area ratio is defined as the ratio of the area where the liquid crystal is driven in the area excluding opaque portions such as metal wirings and MIM elements in the pixel. This configuration has an advantage that a bright color display can be obtained while ensuring contrast.
[0032]
Further, the reflecting plate may have a scattering characteristic such that when a light beam is incident thereon, 80% or more of light is reflected in a 30 ° cone centered on the regular reflection direction. it can. Preferably, it is possible to have a scattering characteristic such that 95% or more of light is reflected in the 30 degree cone. This configuration has an advantage that a bright display can be obtained. Conventionally, for example, JP-A-8-87009 uses a reflector having directivity with a half-value width of 30 degrees in the 43rd to 44th lines in the right column of page 6 of the specification. When the half-value width is 30 degrees, the scattering characteristic is such that approximately 30% of light is reflected in a 30-degree cone, and the scattering is too large compared to the present invention. Such characteristics make the display dark and unusable.
[0033]
Moreover, the said reflecting plate is a semi-transmissive reflecting plate, Comprising: It can be set as the structure provided with the backlight on the back surface. Preferably, the reflecting plate reflects 80% or more of incident light. This configuration has an advantage that it can be seen in a dark environment.
[0034]
Further, the liquid crystal is a nematic liquid crystal twisted approximately 90 degrees, and two polarizing plates can be arranged such that their transmission axes are orthogonal to the rubbing direction of the adjacent substrates. This is an application of the TN mode proposed in Japanese Patent Publication No. 51-013666 to a reflective color liquid crystal device. With this configuration, the reflective color liquid crystal device has the advantages of being bright, having high contrast, and having a wide viewing angle.
[0035]
Further, the product Δn × d of the birefringence Δn of the liquid crystal and the liquid crystal layer thickness d can be made larger than 0.34 μm and smaller than 0.52 μm. More preferably, Δn × d can be 0.40 μm or more and 0.52 μm or less. Most preferably, Δn × d can be 0.42 μm. With this configuration, the reflective color liquid crystal device has the advantage of being bright and having a wide viewing angle.
[0036]
In the conventional reflective type monochrome liquid crystal device, the second minimum condition with little coloring, that is, the condition that Δn × d is about 1.1 μm to 1.3 μm is used. However, in the reflection type color liquid crystal device, since the slight coloration can be compensated by the color filter, it is not necessary to adopt the second minimum condition. Further, in Japanese Patent Application Laid-Open No. 8-87009, the condition of Δn × d = 0.55 μm is adopted as in the 27th line to the 29th line of page 5 of the specification. However, under this condition, Δn × d is darker and more colored than the condition that Δn × d is larger than 0.34 μm and smaller than 0.52 μm.
[0037]
Further, the liquid crystal is a nematic liquid crystal twisted by 90 degrees or more, and two polarizing plates and at least one retardation film can be arranged. If possible, it is desirable to perform multi-line simultaneous selection driving according to the technique disclosed in Japanese Patent Laid-Open No. 6-348230. This configuration has the advantage of being bright at low cost.
[0038]
Moreover, it can be set as the structure which provided the said reflecting plate between a pair of board | substrates, and has arrange | positioned only one polarizing plate. This is an application of the single-polarization-type nematic liquid crystal mode proposed in JP-A-3-223715 to a reflective color liquid crystal device. This configuration has an advantage that a bright color with high color purity can be displayed.
[0039]
Further, the reflection plate may be a specular reflection plate, and a scattering plate may be provided on the outer surface of the substrate located on the incident light side. This configuration has an advantage that a bright color with high color purity can be displayed.
[0040]
In addition, the liquid crystal on the metal wiring can be aligned in the same manner as the liquid crystal in the pixel portion. 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 pixel can be constituted by one dot. This configuration has the advantage that the resolution can be increased during monochrome display.
[0043]
In addition, the electronic device of the present invention can be configured to include a reflective color liquid crystal device as a display portion. With this configuration, the electronic device has the advantages of low power consumption, thin and light weight, and good visibility even in direct sunlight.
[0044]
Moreover, it can be set as the structure attached so that a display part could be moved with respect to a main body so that ambient light could be reflected efficiently to an observer. With this configuration, there is an advantage that a bright display can be obtained under any illumination condition.
[0045]
As can be understood from the above description, the present invention is characterized by using a liquid crystal mode using a polarizing plate and combining it with a bright color filter. There are many liquid crystal display modes using a polarizing plate. For the purpose of the present invention, a liquid crystal display mode capable of bright and black and white display, for example, the TN mode proposed in Japanese Patent Publication No. 51-013666, and Japanese Patent Publication No. 3-50249. Retardation plate compensation type STN mode proposed in Japanese Laid-open Patent Publication No. 3-223715, nematic liquid crystal mode proposed in Japanese Unexamined Patent Publication No. 3-223715, and bistable proposed in Japanese Laid-Open Patent Publication No. 6-235920 A nematic liquid crystal mode for switching is suitable.
[0046]
In the liquid crystal mode using a polarizing plate, more than half of the light is discarded only by the presence of the polarizing plate. Therefore, a liquid crystal mode that does not use a polarizing plate should be more suitable for a reflective color liquid crystal device. However, the liquid crystal mode that does not use a polarizing plate generally has a low contrast in both the PCGH mode and the PDLC mode. Therefore, for example, when a pixel is composed of three dots of red, green, and blue, the contrast is insufficient even if the green dot is set to the bright state and the blue and red pixels are set to the dark state to display green. If so, blue and red are mixed with the green display and the color purity is lowered. However, in the 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. Since the color filter having a low color purity is a bright color filter, the display should be brighter accordingly. In particular, since PCGH is normally black display, the area between dots is black and does not contribute to brightness, and light from a viewing angle direction other than the normal direction of the panel is absorbed by the dye. Despite not using a plate, only about 20% more brightness than the TN mode can be obtained. If the brightness difference is about this level, it can be easily 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 presence of parallax. When only one polarizing plate is used, it is possible to escape from this problem by forming a reflecting plate in the cell, but in the TN mode or STN mode using two polarizing plates, it cannot be escaped. The parallax has already been described in detail in the section “Prior Art”, but there are two problems. One is cancellation of colors, and the other is that the color display becomes dark.
[0048]
The problem of color cancellation is that, if the color filter that has passed at the time of incidence and the color filter that has passed at the time of emission are different, they cancel each other out and become completely dark. That is 1/3. Such a problem occurs 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, even if it passes through a color filter of a different color, there is no darkness.
[0049]
Further, the problem that the color display becomes dark is that when displaying a certain single color, since 2/3 of the entire dots are in a dark state, 2/3 of the light is absorbed at the time of incidence and further 2/3 at the time of emission. Is absorbed, and only 1/9 of the light can be used. This is 1/3 of the brightness when there is no parallax. In order to solve this, it is first necessary to increase the aperture ratio. Specifically, measures were taken such that no black mask was provided outside the dots, MIM using metal wiring in only one direction, MIM wiring in the horizontal direction, and STN using no metal wiring were used. In addition, by further reducing the drive area ratio, an area much smaller than 2/3 of the entire area (for example, about 1/2) is darkened when displaying a single color. In this way, bright color display is possible even with parallax. Note that a means for reducing the drive area ratio or not providing a black mask leads to a decrease in contrast, but a decrease in contrast can be minimized by increasing the thickness of the lower substrate.
[0050]
Embodiments of the present invention will be described below with reference to the drawings.
[0051]
Example 1
FIG. 1 is a diagram showing the main part of the structure of a reflective color liquid crystal device according to Embodiment 1 of the present invention. A pair of substrates each having an electrode on the inner surface facing each other to form a matrix dot group, The constituent elements are a liquid crystal sandwiched between, a color filter of at least two colors, at least one polarizing plate, and a reflector. In the figure, 101 is an upper polarizing plate, 102 is a counter substrate, 103 is a liquid crystal, 104 is an element substrate, 105 is a lower polarizing plate, and 106 is a scattering reflection plate. Electrodes (scanning lines) 108 were provided, and signal lines 109, pixel electrodes 110, and MIM elements 111 were provided on the element substrate 104. Here, 101 and 102, 104 and 105, and 105 and 106 are drawn apart from each other, but this is for clarity of illustration and is actually bonded with glue. Further, the counter substrate 102 and the element substrate 104 are also drawn widely apart. This is also for the same reason, and there is actually only a gap of several μm to several tens of μm. Since FIG. 1 shows the main part of the reflective color liquid crystal device, only 3 × 3 9 dots are shown, but in this embodiment, the number of dots is larger and 480 × 640. It may have 307200 dots or more.
[0052]
The counter electrode 108 and the pixel electrode 110 were made of transparent ITO, and the signal line 109 was made of metal Ta. MIM element is insulating film Ta ₂ O ₅ Is sandwiched between metal Ta and metal Cr. The liquid crystal 103 is a nematic liquid crystal twisted 90 degrees, and the polarization axes of the upper and lower polarizing plates are orthogonal to each other. This is a general TN mode configuration. The color filter 107 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 arranged in a stripe pattern.
[0053]
FIG. 2 is a diagram showing the spectral characteristics of the color filter 107. In FIG. 2, the horizontal axis indicates the wavelength of light, the vertical axis indicates the transmittance, 201 indicates the spectrum of the red filter, and 202 indicates the spectrum of the cyan filter. Spectral measurements were made on a single counter substrate using a microspectrophotometer and corrected for 100% transmission including glass substrate and transparent electrode, and overcoat and undercoat if present. 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 this is a very light color filter, it is more accurate to express “pink” instead of “red”. However, in order to avoid confusion, the following description is unified with pure color expression.
[0054]
The reflection type color liquid crystal device produced as described above has a reflectance of 24% during 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, cyan display colors were x = 0.28, y = 0.31. This is about 60% brighter and the same contrast ratio of the conventional reflective type monochrome liquid crystal device, and is a characteristic that can be sufficiently used under normal indoor illumination light or outdoors in the daytime.
[0055]
Reflective color liquid crystal devices using color filters that exhibit a transmittance of less than 30% in the wavelength range of 450 nm to 660 nm are either dark and require special illumination, or white balance is out of order. Therefore, it cannot withstand normal use for either reason that white cannot be displayed.
[0056]
In Example 1, the transparent electrode is provided on the color filter, but conversely, there is no particular problem even if the color filter is provided on the transparent electrode. Further, 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, the effect of the present invention is not changed even if the TFT element is used.
[0057]
(Example 2)
FIG. 3 is a diagram showing the spectral characteristics of the color filter of the reflective color liquid crystal device in Example 2 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 composed of two colors of red and cyan. In FIG. 3, the horizontal axis indicates the wavelength of light, the vertical axis indicates the transmittance, 301 indicates the spectrum of the red filter, and 302 indicates the spectrum of the cyan filter. Each color filter has a transmittance of 50% or more in the 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 reflectance of 30% when displaying white, a contrast ratio of 1:15, and can display four colors of white, red, cyan and black, and 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 slightly more than 70% of a conventional reflective 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 with respect to light of all wavelengths in the range of 450 nm to 660 nm, it can be used in an environment substantially equivalent to a conventional reflective monochrome liquid crystal device. A bright reflective color liquid crystal device can be obtained. When the color filter is composed of two colors as in the present embodiment, a good white color can be obtained 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. In order to obtain a balance, the other color filter inevitably has a transmittance of 50% or more as well. However, this is not always the case when using three or more color filters. An example of this will be introduced later in Example 9.
[0060]
(Example 3)
FIG. 1 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 3 of the present invention. FIG. 2 is a diagram showing the spectral characteristics of the color filter. In this example, the thickness of the substrate located on the reflecting plate side of the pair of substrates was set to 200 μm or more. Since the configuration of the third embodiment is basically the same as that of the reflective color liquid crystal device described in the first embodiment, the description of each symbol 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 drive area ratio was 75%.
[0061]
In Example 3, the thickness of the lower substrate was variously changed. FIG. 4 shows the contrast when the thickness of the element substrate 104 is changed. In FIG. 4, the horizontal axis represents the thickness of the element substrate 104, the vertical axis represents the contrast, 401 represents a collection of points indicating the contrast to the thickness of each element substrate 104 in Example 3, and 402 represents the thickness of each element substrate 104 in the comparative example. It is a collection of points indicating contrast with respect to the height. The display colors at the time of color display were x = 0.39 and y = 0.32 at the time of red display, and cyan was near x = 0.28 and y = 0.31.
[0062]
Since the drive area ratio is 75%, when the thickness of the element substrate is zero, the contrast can only be 100 / (100−75) = 4 at the maximum. However, when the thickness of the element substrate 104 is set to 200 μm or more, the parallax effect, that is, the shadow of the adjacent dots alleviates light leakage between the dots, thereby obtaining a good contrast of 1:15 or more. 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 expressed as “1.25 times or more of the shorter one of the vertical and horizontal dot pitches”, “ It may be expressed as “same as four times or more”.
[0064]
Example 4
FIG. 5 is a diagram showing the spectral characteristics of the color filter of the reflective color liquid crystal device in Example 4 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 indicates the wavelength of light, the vertical axis indicates the transmittance, 501 indicates the spectrum of the red filter, and 502 indicates the spectrum of the cyan filter. Each color filter has a transmittance of 60% or more in the 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% during white display, a contrast ratio of 1:15, can display four colors of white, red, cyan and black, and the red display color is x = 0.33. y = 0.33, cyan display color was x = 0.30, y = 0.31. This is about 80% of the brightness of a conventional reflective monochrome liquid crystal device and an equivalent contrast ratio.
[0066]
As described above, when any color filter has a transmittance of 60% or more with respect to light of all wavelengths in the range of 450 nm to 660 nm, input means such as a touch key is provided on the entire surface of the liquid crystal device. A bright reflective color liquid crystal device can be obtained which can be used without any problem even if it is attached. However, if a color filter having an average transmittance exceeding 90% in the same wavelength range is used, the display color becomes very light and it becomes difficult to identify the color.
[0067]
(Example 5)
FIG. 6 is a diagram showing the main part of the structure of the reflective color liquid crystal device in Example 5 of the present invention. In this embodiment, the color filters are arranged so that the colors of adjacent dots are different. First, the configuration will be described. Reference numeral 601 denotes an upper polarizing plate, 602 denotes a counter substrate, 603 denotes a liquid crystal, 604 denotes an element substrate, 605 denotes a lower polarizing plate, and 606 denotes a scattering reflection plate. Line) 608, and a signal line 609, a pixel electrode 610, and an MIM element 611 are provided over 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) that are complementary to each other, and draws a checkered pattern in a mosaic pattern. 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 shifted in the left-right direction, the viewing angle direction to be colored and the viewing angle direction to be decolored 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). It has been confirmed by experiments that such a phenomenon is considerably mitigated by arranging the checkerboard pattern in a mosaic pattern as shown in FIG. It was also found that color mixing is good even when the number of pixels is relatively small. This is considered to be because, in the case of the mosaic arrangement, the viewing angle direction to be colored and the viewing angle direction to be decolored coexist, so that at least one of the eyes looks colored. The color filter had the same spectral characteristics as in FIG. 3 of Example 2, and the brightness and contrast ratio were comparable to those of Example 2. Although an example of the mosaic arrangement has been described here, other arrangements including the triangle arrangement are effective as long as the adjacent dots have different colors.
[0069]
(Example 6)
FIG. 7 is a diagram showing the spectral characteristics of the color filter of the reflective color liquid crystal device in Example 6 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 indicates the wavelength of light, the vertical axis indicates 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 the 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% when displaying white, a contrast ratio of 1:17, and can display four colors of white, green, magenta, and black. The green display color is x = 0.31. y = 0.35, magenta display color was x = 0.32, y = 0.29. This is about 80% of the brightness of a conventional reflective monochrome liquid crystal device and an equivalent contrast ratio.
[0071]
As two complementary colors, red and cyan, green and magenta, as well as blue and yellow can be considered. However, it is better to display red colors like the former two. It is more preferable in terms of
[0072]
(Example 7)
FIG. 8 is a diagram showing the main part of the structure of the reflective color liquid crystal device in Example 7 of the present invention. First, the configuration will be described. Reference numeral 801 denotes an upper polarizing plate, 802 denotes a counter substrate, 803 denotes a liquid crystal, 804 denotes an element substrate, 805 denotes a lower polarizing plate, 806 denotes a scattering reflector, and 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 are provided over the element substrate 804. A weak anti-glare treatment was applied on the upper polarizing plate for the purpose of suppressing glare of illumination light.
[0073]
Here, the color filter 807 is composed of three colors of red (indicated by “R” in the drawing), green (indicated by “G” in the drawing), and blue (indicated by “B” in the drawing). As shown in FIG.
[0074]
FIG. 9 is a diagram showing the spectral characteristics of the color filter 807. In FIG. 9, the horizontal axis indicates the wavelength of light, the vertical axis indicates 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. Any color filter has a transmittance of 50% or more in the 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 produced as described above has a reflectance of 28% during white display, a contrast ratio of 1:14, and a full color display is possible, and the red display color is 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 brightness and equivalent contrast ratio of the conventional reflective type monochrome liquid crystal device, and it is a characteristic that video images can be enjoyed without requiring special illumination.
[0076]
(Example 8)
FIG. 10 is a diagram showing the main part of the structure of the reflective color liquid crystal device in Example 8 of the present invention. In this embodiment, at least one color filter among the color filters has a transmittance of 50% or more for light of all wavelengths in the range of 450 nm to 660 nm. In addition, the color filter has three colors, red, green, and blue, and either the red or blue color filter is orange or cyan. First, the configuration will be described. Reference numeral 1001 denotes an upper polarizing plate, 1002 denotes an element substrate, 1003 denotes a liquid crystal, 1004 denotes a counter substrate, 1005 denotes a lower polarizing plate, and 1006 denotes a scattering reflection plate. A filter 1010 is provided, and a signal line 1007, an MIM element 1008, and a pixel electrode 1009 are provided over the element substrate 1002. The color filter 1010 is a pigment dispersion type, and can be selected from 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). It is made up.
[0077]
FIG. 11 is a diagram showing the spectral characteristics of the color filter 1010. In FIG. 11, the horizontal axis represents the light wavelength, the vertical axis represents the transmittance, 1101 represents the spectrum of the red filter, 1102 represents the spectrum of the green filter, and 1103 represents the spectrum of the blue filter. 1101, 1102, and 1103 are all light color filters, but images displayed with such color filters are light. In particular, red and blue have low visibility and are difficult to distinguish colors. Therefore, a bright color filter that transmits light in a wider wavelength range was used even if the color changed slightly.
[0078]
When a red filter with low color purity was used in place of the red filter, a very bright red was displayed although it looked slightly orange. 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. In addition, when a blue filter with low color purity was used instead of the blue filter, a very bright blue was displayed although it was slightly cyanish. 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 the color filter is used, 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 showing the spectral characteristics of the color filter of the reflective color liquid crystal device in Example 9 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, the vertical axis represents the transmittance, 1201 represents the spectrum of the red filter, 1202 represents the spectrum of the green filter, and 1203 represents the spectrum of the blue filter. The minimum transmittance of light having a wavelength in the range of 450 to 660 nm of the red color filter is smaller than the minimum transmittance of light having a wavelength in the range of 450 to 660 nm of the blue and green color filters. Here, only the green filter has a transmittance of 50% or more in the wavelength range of 450 nm to 660 nm. Further, the minimum transmittance of the red filter for light having a wavelength in the range of 450 nm to 660 nm is clearly smaller than that of the blue filter and the green filter. By using such a red filter, the most appealing red color can be displayed vividly. In addition, the blue filter spectrum 1203 is made close to cyan for the purpose of compensating for the darkening of red. For this reason, bright white and small white could be displayed.
[0080]
The reflective color liquid crystal device produced as described above has a reflectance of 26% during white display, a contrast ratio of 1:13, and can display full color, and the red display color is x = 0.41 and y = 0. .30, the green display color was x = 0.31, y = 0.36, and the blue display color was x = 0.26, y = 0.28. This is about 70% of brightness and equivalent contrast ratio of the conventional reflective type monochrome liquid crystal device. Since red is particularly emphasized, color reproducibility is not sufficient. Therefore, it is more suitable for displaying a portable information device or the like than displaying a video image.
[0081]
(Example 10)
FIG. 10 is a diagram showing the main part of the structure of the reflective color liquid crystal device in Example 10 of the present invention. The configuration will be described. Reference numeral 1001 denotes an upper polarizing plate, 1002 denotes an element substrate, 1003 denotes a liquid crystal, 1004 denotes a counter substrate, 1005 denotes a lower polarizing plate, and 1006 denotes a scattering reflection plate. A filter 1010 is provided, and a signal line 1007, an MIM element 1008, and a pixel electrode 1009 are provided over the element substrate 1002. The color filter 1010 is a pigment dispersion type, and can be selected from 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). It is made up.
[0082]
FIG. 13 is a diagram showing the spectral characteristics of the color filter 1010. In FIG. 13, the horizontal axis indicates the wavelength of light, and the vertical axis indicates the transmittance. 1301 and 1311 indicate the red filter spectrum, 1302 and 1312 indicate the green filter spectrum, and 1303 and 1313 indicate the blue filter spectrum. 1301 and 1311, 1302 and I312, and 1303 and 1313 have the same color filter material, but the thicknesses are different, 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 graph plotting the average transmittance when the thickness of the color filter is variously changed. In the figure, 1401 is a blue filter, 1402 is a green filter, and 1403 is a red filter. In either case, the thinner the color filter, the higher the average transmittance. The thickness of a normal pigment-dispersed color filter used in the transmission type is about 0.8 μm. However, when such a color filter is used, special illumination such as spotlight is used under direct sunlight outdoors. Unless it was done, the display was dark enough to be discerned. 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, 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 any of the color filters was 75% or more, a brightness that could be sufficiently used under normal room illumination light with an illuminance of about 200 lux was obtained. Further, when the thickness was 0.8 μm or more, that is, when the average transmittance of any color filter was 90% or less, it was possible to display the color clearly. Thus, the pigment dispersion 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 the main part of the structure of the reflective color liquid crystal device in Example 11 of the present invention. In this embodiment, the color filter is provided only in a part of the light-modulable area in each dot. First, the configuration will be described. Reference numeral 1501 denotes an upper polarizing plate, 1502 denotes an element substrate, 1503 denotes a liquid crystal, 1504 denotes a counter substrate, 1505 denotes a lower polarizing plate, and 1506 denotes a scattering reflection plate. A filter 1510 is provided, and a signal line 1507, an MIM element 1508, and a pixel electrode 1509 are provided over the element substrate 1502. The region where light modulation can be performed in one dot is a region where the concave ITO on the element substrate overlaps with the strip-shaped ITO on the counter substrate, and the outline is indicated by a broken line on the ITO of the counter substrate. . (Please 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 are formed of transparent ITO, and the signal line 1507 is formed of metal Ta. MIM element is insulating film Ta ₂ O ₅ Is sandwiched between metal Ta and metal Cr. The liquid crystal 1503 is a nematic liquid crystal twisted 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 would be 1.34 μm. The upper and lower polarizing plates were arranged so that their absorption axes were parallel to the rubbing axis of the adjacent substrate. This is the brightest and least colored TN mode configuration. The color filter 1510 is composed of two colors of red (indicated by “R” in the drawing) and cyan (indicated by “C” in the drawing) that are complementary to each other. It was provided only in the department.
[0086]
FIG. 16 is a diagram showing the spectral characteristics of the color filter 1510. In FIG. 16, the horizontal axis represents the light wavelength, the vertical axis represents the transmittance, 1601 represents the spectrum of the red filter, and 1602 represents 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 a case where the color filter is provided on the entire surface, and when the color filter is provided only on a part thereof, the average value in the region where the light modulation is possible is referred to as the average transmittance.
[0087]
FIG. 17 shows the result of obtaining the average transmittance at that time by changing the ratio of the area where the color filter is provided in the light-modulable region. 1701 is the average transmittance of dots provided with a red filter, and 1702 is the average transmittance of dots provided with a cyan filter.
[0088]
When the color filter area ratio was 100%, that is, when a color filter was provided on the entire surface, it was dark enough that the display could not be determined unless it was exposed to direct sunlight outdoors or special illumination such as a spotlight. When the color filter area ratio is 45% or less, that is, when the average transmittance of any color filter is 70% or more, the environment of a relatively bright room with an illuminance of about 1000 lux, for example, an office desk illuminated with a fluorescent lamp stand. The brightness that can be used comfortably was obtained below. When the color filter area ratio was 35% or less, that is, when the average transmittance of any color filter was 75% or more, the brightness that can be sufficiently used under normal room illumination light with an illuminance of about 200 lux was obtained. Further, when the color filter area ratio was 15% or more, that is, when the average transmittance of any one 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 any color filter was 90% or less, it was possible to display the color clearly. In addition, when any color filter was used, a high contrast ratio of 1:15 or more was obtained.
[0089]
The color filter used in Example 11 has the same spectral characteristics and the same brightness as the color filter used in the normal transmission type except that cyan is used. Such a color filter is desirably provided in an area of 45% or less, preferably 35% or less, and 15% or more, preferably 25% or more, of the light-modulable 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 if the TFT element is used, the effect of the present invention is achieved. There is no change.
[0091]
(Example 12)
The twelfth embodiment is also a reflective color liquid crystal device in which the color filter is provided only in a part of the light-modulable region in each dot. The structure of the reflective color liquid crystal device in this example is the same as that of the reflective color liquid crystal device of Example 11 shown in FIG. 15, but Example 12 differs in the characteristics of the color filter.
[0092]
FIG. 18 is a graph showing the spectral characteristics of the color filter used in Example 12. In FIG. In FIG. 18, the horizontal axis represents the light wavelength, the vertical axis represents the transmittance, 1801 represents the spectrum of the red filter, and 1802 represents 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 conventional processes without problems such as dispersibility of the pigment.
[0093]
FIG. 19 shows the result of obtaining the average transmittance at that time by changing the ratio of the area where the color filter is provided in the light-modulable region. Reference numeral 1901 denotes the average transmittance of dots provided with a red filter, and 1902 denotes the average transmittance of dots provided with a cyan filter.
[0094]
When the color filter area ratio was 100%, that is, a color filter was provided on the entire surface, the display was dark and difficult 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 any color filter is 70% or more, the environment of a relatively bright room with an illuminance of about 1000 lux, for example, an office desk illuminated with a fluorescent lamp stand. The brightness that can be used comfortably was obtained below. When the color filter area ratio was 40% or less, that is, when the average transmittance of any color filter was 75% or more, the brightness that can be sufficiently used under normal room illumination light with an illuminance of about 200 lux was obtained. Further, when the color filter area ratio was 15% or more, that is, when the average transmittance of any one of the color filters was 90% or less, red and cyan could be distinguished. When the color filter area ratio was 25% or more, that is, when the average transmittance of any color filter was 90% or less, it was possible to display the color clearly. In addition, when any color filter 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 the normal transmission type. Such a color filter is desirably provided in an area of 50% or less, preferably 40% or less, and 15% or more, preferably 25% or more, of the light-modulable region.
[0096]
(Example 13)
FIG. 20 is a diagram showing the main part of the diagram structure of the reflective color liquid crystal device in Example 13 of the present invention. Also in this embodiment, the color filter is provided only in a part of the light-modulable area in each dot. The configuration will be described. Reference numeral 2001 denotes an upper polarizing plate, 2002 denotes an element substrate, 2003 denotes a liquid crystal, 2004 denotes a counter substrate, 2005 denotes a lower polarizing plate, and 2006 denotes a scattering reflector. A counter electrode (scanning line) 2011 and a color are provided on the counter substrate 2004. A filter 2010 is provided, and a signal line 2007, an MIM element 2008, and a pixel electrode 2009 are provided over the element substrate 2002. The region where light modulation is possible in one dot is a region where the concave ITO on the element substrate and the strip-like ITO on the counter substrate overlap each other, and the outline thereof is indicated by a broken line on the ITO of the counter substrate.
[0097]
The color filter 2010 is composed of two colors, red (indicated by “R” in the figure) and cyan (indicated by “C” in the figure), which are complementary to each other. Provided. It is desirable to dispose each color filter so that there is no other color filter. With such an arrangement, display with little color mixing is possible. Because there is usually a distance at least as much as the thickness of the counter substrate between the color filter layer and the reflector, light incident through the red filter exits through the cyan filter, or Color confusion occurs due to the reverse, but the probability decreases when the above arrangement is adopted.
[0098]
(Example 14)
FIG. 21 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 14 of the present invention. Also in this embodiment, the color filter is provided only in a part of the light-modulable area in each dot. The configuration will be described. Reference numeral 2101 denotes an upper polarizing plate, 2102 denotes an element substrate, 2103 denotes a liquid crystal, 2104 denotes a counter substrate, 2105 denotes a lower polarizing plate, 2106 denotes a scattering reflector, and a counter electrode (scanning line) 2112 and a color are provided on the counter substrate 2104. A filter 2111 is provided, and a signal line 2107, an MIM element 2108, and a pixel electrode 2109 are provided on the element substrate 2102.
[0099]
The color filter 2111 is made up of two colors, red (indicated by “R” in the figure) and cyan (indicated by “C” in the figure), which are complementary to each other. Divided into five areas and arranged in a checkered pattern. If a color filter is provided only in a part of the dots, the part without the color filter is easily noticeable in white, but there is an advantage that the color mixture is good if it is arranged in such a fine area. Of course, the number of divisions may be two, but it is more effective to divide the number into three or more.
[0100]
Further, a black mask 2110 (indicated by “BK” in the drawing) is provided at a position covering the scanning lines. This black mask is particularly effective for preventing reflection when the counter substrate 2104 is disposed on the upper side and the element substrate 2102 is disposed on the lower side in FIG. Further, it is possible to substitute red, cyan, or a superposition thereof without using a black pigment.
[0101]
(Example 15)
In the reflective color liquid crystal device of Example 15, the color filter is provided only in a part of the light-modulable region in each dot. The reflective color liquid crystal device in this embodiment has the same structure as the reflective color liquid crystal device of the twelfth embodiment shown in FIG. 15, the reflective color liquid crystal device of the thirteenth embodiment shown in FIG. 20, and the embodiment 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. In general, 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, two new effects were obtained by arranging as in this embodiment. One is an increase in viewing angle, and the other is an improvement in color purity in a halftone.
[0103]
FIG. 22 is a diagram showing the voltage reflectance characteristics of the reflective color liquid crystal device in Example 15 of the present invention. The horizontal axis represents the voltage that is effectively applied to the liquid crystal, and the vertical axis represents the reflectance normalized to 100% when no voltage is applied. Reference numeral 2201 denotes a characteristic of a region where no color filter is provided in a region where light modulation is possible, and 2202 denotes a characteristic of a region where a color filter is provided. Due to the voltage drop due to the capacitive division, 2202 is worse in voltage reflectivity characteristics than 2201. In other words, it is less likely that a voltage is applied to the liquid crystal as compared with a region where the color filter is not provided. As described above, since two regions having different voltage application conditions exist in one pixel, the effects disclosed in Japanese Patent Application Laid-Open Nos. 2-12 and 4-348323 (generally “halftone method”). The viewing angle characteristics are improved. 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 showing the structure of the color filter substrate of the reflective color liquid crystal device in Example 16 of the present invention. In this embodiment, the color filter is provided only in a part of the light-modulable area in each dot, and the light-modulable area is not provided with the color filter, and the light-modulation is impossible. In the region, a transparent layer in the visible light region was formed with substantially the same thickness as the color filter. (A) is a front view, (b) is sectional drawing. First, the configuration will be described. A rectangular area 2304 surrounded by a broken line in FIG. 2309 is a glass substrate, 2301 is a red filter, 2303 is a green filter, 2302 is a blue filter, 2305 is a gap between dots, hatching area 2308 is acrylic, 2307 is a protective film, and 2306 is an ITO transparent electrode.
[0105]
The spectral characteristics of the color filter used here are shown in FIG. In FIG. 25, the horizontal axis represents the light wavelength, the vertical axis represents the transmittance, 2501 represents the spectrum of the blue filter, 2502 represents the spectrum of the green filter, and 2503 represents the spectrum of the red filter. However, this is a characteristic when the color filter forming 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. In FIG. 26, the horizontal axis indicates the wavelength of light, the vertical axis indicates 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 is formed in the same thickness as the color filter in the portion where the color filter is not formed in FIG. At this time, the thicknesses of the color filters 2301, 2302, 2303 and acrylic 2308 are all about 0.2 μm. In addition, an acrylic transparent layer 2308 was formed in the inter-dot gap 2305 without forming a light-shielding film (black stripe) formed between the dots used in a normal transmissive color liquid crystal device. Further, a protective film 2307, an ITO electrode 2306, and an alignment film (not shown) for aligning liquid crystals are sequentially formed on the color filter, and are superimposed on an MIM (metal-insulating film-metal) active matrix substrate. A liquid crystal device was constructed. The TN mode was adopted as the liquid crystal mode at this time.
[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 an 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 partially The formed green color filter, 2411 a partially formed blue color filter, 2412 an acrylic, 2413 a signal electrode, 2404 a lower polarizing plate, and 2405 an aluminum reflector.
[0108]
In a reflective color liquid crystal device using a substrate in which a color filter is simply formed with an area ratio of 50% in one dot, the alignment of the liquid crystal is disturbed by the step between the color filter forming portion and the unformed portion, and the contrast is 1: 8. On the other hand, a reflective color liquid crystal device using a substrate in which acrylic is formed on the color filter non-formed portion with the same thickness as the color filter can display a high quality image without disturbing the liquid crystal alignment. The contrast at this time was 1:20. FIG. 27 shows a color filter configuration in the case where the acrylic transparent layer is not formed in the portion where the color filter is not formed. (A) is a front view, (b) is a sectional view. 2707 is a glass substrate, 2701 is a partially formed red filter, 2703 is partially formed green filter, 2702 is partially formed blue filter, 2706 is a protective film, 2704 is 1 dot, 2705 is a pixel Is the gap between. As apparent from the 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, the active matrix reflective color liquid crystal device is described. However, the present invention can also be applied to a simple matrix reflective color liquid crystal device. The present invention is more effective when unevenness on the substrate surface greatly affects the liquid crystal alignment as in the STN mode. In this embodiment, the “mosaic arrangement” is adopted as the color filter arrangement, but the '93 latest liquid crystal process technology (press journal) pp. “Triangle arrangement” and “stripe arrangement” as shown in FIG.
[0110]
(Example 17)
In the seventeenth embodiment, the color filter is provided only in a part of the region where light modulation is possible in each dot, and the region where the color filter is not provided in the region where light modulation is possible is impossible. In the region, a transparent layer in the visible light region was formed with substantially the same thickness as the color filter.
[0111]
FIG. 28 is a diagram showing the structure of the color filter substrate of the reflective color liquid crystal device in Example 17 of the present invention. (A) is a front view, (b) is sectional drawing. 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 hatching area 2806 is acrylic.
[0112]
The spectral characteristics of the color filter used here are shown in FIG. In FIG. 29, the horizontal axis indicates the wavelength of light, the vertical axis indicates 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 a characteristic when the color filter forming area is 100%. A color filter exhibiting such spectral characteristics was formed in one dot in FIG. 28 at an area ratio of 30%. As a result, spectral characteristics as shown in FIG. 26 were obtained on average within one dot.
[0113]
Further, acrylic 2807 was formed in the same thickness as the color filter in the portion where the color filter was not formed in FIG. At this time, the thickness of the color filter and the acrylic is about 0.8 μm, and the light shielding film (black stripe) that is configured between the dots used in a normal transmission type color liquid crystal device is not formed. A 2807 transparent layer was formed. Further, an alignment film for aligning the liquid crystal was formed and superimposed on the TFT substrate to constitute 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 reflective color liquid crystal device using a substrate in which a color filter is only formed at an area ratio of 30% in one dot, the alignment of the liquid crystal is disturbed by the step between the color filter forming portion and the unformed portion, and the contrast is 1: 5. On the other hand, a reflective color liquid crystal device using a substrate in which acrylic is formed on the color filter non-formed portion with the same thickness as the color filter can display a high quality image without disturbing the 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 also be applied to a simple matrix reflective color liquid crystal device. The present invention is more effective when unevenness on 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 filter, but 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 used. Two related color filters can also be used.
[0117]
(Example 18)
In the sixteenth and seventeenth embodiments, the color filter is partially formed at substantially the center of one dot. However, the color filter may be formed as shown in FIGS. 32 (a) and 32 (b). 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 remaining half is a region 3203 where a color filter is not formed. (B) is an area 3202 where the right half or left half of one dot 3201 is formed with a color filter, and the remaining half is an area 3203 where no color filter is formed. In addition, as shown in FIGS. 32C and 32D, the inside of one dot 3201 may be divided into two or more, and a part 3202 may be formed as a color filter area, and the rest may be set as a region 3203 where no color filter is formed. Even when such various color filters are used, a high-quality reflective color liquid crystal device can be realized.
[0118]
(Example 19)
Table 1 shows changes in characteristics when the level difference between the color filter and the transparent layer was changed in Example 16. As the level difference becomes smaller, both image quality and contrast are improved. When the step is 0.5 μm or less, a contrast of 1:10 or more is obtained, and when it is 0.1 μm or less, a contrast of 1:15 or more is obtained.
[Table 1]

[0119]
(Example 20)
In Example 16 and Example 17, acrylic was used for the transparent layer filling the level difference between the color filter forming part and the non-forming part, but a high-quality reflective color liquid crystal device could be realized even if polyimide was used. Similarly, a reflective color liquid crystal device with high image quality could be realized even when polyvinyl alcohol was used for the transparent layer. The results are summarized in Table 2. Both image quality and contrast are improved compared to the case without a transparent layer.
[Table 2]

[0120]
In Examples 16 and 17, a general aluminum reflector or silver reflector was used as the reflector. G. A holographic reflector (SID '95 DIGEST, PP. 176-179) announced by Chen et al. Can also be used.
[0121]
(Example 21)
FIG. 33 is a diagram showing the main part of the structure of the reflective color liquid crystal device in Example 21 of the invention. In this embodiment, the color filter is provided only for the number of dots that is three quarters or less of the total number of dots. The configuration will be described. Reference numeral 3301 denotes an upper polarizing plate, 3302 denotes an element substrate, 3303 denotes a liquid crystal, 3304 denotes a counter substrate, 3305 denotes a lower polarizing plate, 3306 denotes a scattering reflector, and a counter electrode (scanning line) 3311 and a color are provided on the counter substrate 3304. A filter 3310 is provided, and a signal line 3307, an MIM element 3308, and a pixel electrode 3309 are provided over the element substrate 3302.
[0122]
The color filter 3310 is composed of two colors, 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 filter used here is the same as that of Example 1, and its spectral characteristics are shown in FIG.
[0123]
FIG. 34 is a diagram showing the arrangement of the color filters as seen 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 all dots, a cyan filter was provided for 1/3 dots, and a color filter was not provided for the remaining 1/3 dots. Further, (a), (b), (c), and (d) in FIG. 34 show distributions of on dots and off dots when white, red, cyan, and black are displayed, respectively. The hatched dots are on dots, that is, the dark state, and the dots that are not hatched are off dots, that is, the bright state. When display is performed in this manner, color display is performed with 2/3 of the dots as a whole, so that brighter display than usual is possible. Further, when displaying halftones by color display, there is an advantage that vivid colors can always be displayed by adjusting the brightness mainly with dots having no color filter. For example, when dark red is displayed, the dots provided with the red filter are all turned off, the dots provided with the cyan filter are turned on, and the dots not provided with the color filter are turned on half.
[0124]
Another color filter arrangement is shown in FIG. A red filter was provided for the entire ¼ dot, a cyan filter was provided for the ¼ dot, and a color filter was not provided for the remaining ½ dot. 35A, 35B, 35C, and 35D show the distribution of on dots and off dots when white, red, cyan, and black are displayed, respectively. When display is performed in this way, color display is performed with 3/4 dots as a whole, so that a brighter display than the color filter arrangement of FIG. 35 is possible.
[0125]
As another example, FIG. 36 shows an arrangement when three color filters of red, green, and blue 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. Yes. Red filter is provided for 1/6 dots, green filter is provided for 1/6 dots, blue filter is provided for 1/6 dots, and no color filter is provided for the remaining 1/2 dots. It was. In addition, (a), (b), (c), and (d) of FIG. 36 show the distribution of on dots and off dots when white, red, green, and blue are displayed, respectively. When display is performed in this manner, bright display is possible because color display is performed with 4/6 dots as a whole.
[0126]
In addition, a red filter is provided for the entire ¼ dot, a green filter is provided for the ¼ dot, a blue filter is provided for the ¼ dot, and a color filter is provided for the remaining ¼ 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 dots as a whole.
[0127]
(Example 22)
FIGS. 37A and 37B are diagrams schematically showing the structure of a reflective color liquid crystal device in Example 22 of the invention, in which 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. 3701 is a frame case, 3702 is an upper polarizing plate, 3703 is an upper substrate, 3704 is a color filter, 3705 is a lower substrate, and 3706 is a polarizing plate with a reflector. Since the drawing becomes 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. Although (b) is a horizontal cross-sectional view, the vertical cross-sectional view is the same as (b). Note that the terms “drive display area” and “effective display area” refer to “area having a display function in a liquid crystal display device”, “drive display area, and it” in ED-2511A of the Japan Electronic Machinery Manufacturers Association (EIAJ). It is defined as an “effective area as a subsequent screen”. That is, the drive display area is an area where 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. By configuring in this way, the reflective color liquid crystal device of Example 22 has the advantage that the display looks bright. Usually, in transmissive color display, a color filter is provided only in the drive display area, and a black mask made of metal or resin is provided in the outer area. However, in the reflective color display, the metal black mask is glaring and cannot be used. In addition, the resin black mask increases the cost because the original color filter is not provided with a black mask. However, if nothing is provided outside the drive display area, the outside becomes bright and the drive display area looks relatively dark. Therefore, it is effective to provide the same color filter as the inner side outside the drive display area, preferably in the same pattern, in order to make the display brighter.
[0129]
(Example 23)
In a transmissive color liquid crystal device, a black mask is generally provided outside the dots. However, if a black mask is provided in a reflective color liquid crystal device, high contrast can be obtained, but the display becomes extremely dark. In particular, in the liquid crystal mode where parallax is inevitable, such as the TN mode and STN mode, the brightness is proportional to the square of the aperture ratio because light is absorbed by the black mask twice when light enters and exits. It has the nature of Accordingly, it is impossible to provide a black mask in the reflective color liquid crystal device, but conversely, if no light absorber is provided outside the dots, the contrast is remarkably lowered. Therefore, Embodiment 23 of the present invention is characterized in that a black mask is not provided outside the dots, but a color filter having an absorption comparable to or smaller than the area inside the dots is provided instead.
[0130]
FIG. 38 is a diagram showing the color filter arrangement of the reflective color liquid crystal device in Example 23 of the present invention. As described above, in this embodiment, a black mask is not provided in the area outside each dot, but instead, a color filter having an absorption comparable to or smaller than the area in the dot is provided. Although the basic configuration and the spectral characteristics of the color filter are the same as those in FIGS. 6 and 3 of Example 5, the arrangement of the color filter in the region outside the dots has been devised. In FIG. 38, a “laterally convex” area 3801 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 above-described dot. A region 3802 hatched obliquely from the upper right to the lower left is a cyan filter, and a region 3803 hatched in the cross is a red filter.
[0131]
In FIG. 38A, 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 they are arranged apart from each other. In (c), a red filter is disposed outside the dot. In either case, since the region outside the dot has absorption that is the same as or smaller than that in the dot but is not zero, a bright and high-contrast display can be obtained. Each characteristic is as follows: (a) 30% reflectivity for white display and a contrast ratio of 1:15, (b) 33% reflectivity and a contrast ratio of 1:13, (c) 29% and a ratio of 1:16. there were.
[0132]
(Example 24)
FIG. 39 is a diagram showing the color filter arrangement of the reflective color liquid crystal device in Example 24 of the present invention. In this embodiment as well, a black mask is not provided in the area outside each dot, but a color filter having an absorption comparable to or smaller than the area in the dot is provided instead. The basic configuration and spectral characteristics of the color filters are the same as those in FIGS. 8 and 12 of Example 9, but the arrangement of the color filters in the area outside the dots has been devised. In FIG. 39, a “laterally 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. A region 3902 hatched diagonally from the upper left to the lower right is a blue filter, a region 3903 hatched diagonally from the upper right to the lower left is a green filter, and a region 3904 hatched in the cross is a red filter. is there.
[0133]
In FIG. 39A, three color filters are provided outside the dots, but they are arranged apart from each other. The separation distance was set in anticipation of the maximum misalignment when creating the color filter. That is, FIG. 39B shows the color filter arrangement in the case where the maximum possible misalignment occurs, but even in this case, the color filters of different colors are prevented from overlapping each other. Since overlapping color filters is almost synonymous with the presence of a black mask, this should 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 the reflective color liquid crystal device in Example 25 of the invention. Also in this example, a black mask was not provided in the area outside each dot, but instead a color filter having an absorption comparable to or smaller than the area in the dot was provided. First, the configuration will be described. Reference numeral 4001 denotes an upper polarizing plate, 4002 denotes a counter substrate, 4003 denotes a liquid crystal, 4004 denotes an element substrate, 4005 denotes a lower polarizing plate, and 4006 denotes a scattering reflector. On the counter substrate 4002, a color filter 4007 and a counter electrode (scanning) Line) 4008, and a signal line 4009, a pixel electrode 4010, and an MIM element 4011 are provided over the element substrate 4004. This color filter has a stripe arrangement that is common in data displays such as PCs. The spectral characteristics of the color filter are the same as those in FIG.
[0135]
FIG. 41 is a diagram showing a color filter arrangement of the reflective color liquid crystal device in Example 25 of the present invention. In FIG. 41, a “laterally 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 the upper left to the lower right is a blue filter, a region 4103 hatched diagonally from the upper right to the lower left is a green filter, and a region 4104 hatched in the 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 on the top and bottom and separated from each other on the left and right. The separation distance was set in anticipation of the maximum misalignment when creating the color filter. That is, FIG. 41B shows the color filter arrangement in the case where the maximum possible misalignment occurs, but 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 cross sectional view showing an essential part of the structure of the reflective color liquid crystal device in Example 26 of the invention. In this example, a color filter was provided on the outer surface of the substrate located on the reflector side of the pair of substrates. The configuration will be described. Reference numeral 4201 denotes an upper polarizing plate, 4202 denotes an element substrate, 4203 denotes a liquid crystal, 4204 denotes a counter substrate, 4205 denotes a lower polarizing plate, 4206 denotes 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 is provided over the counter substrate 4204. Although not shown in this cross-sectional view, the signal line and the pixel electrode are connected via the MIM element. Further, 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 reflection plate side.
[0138]
The spectral characteristics of the color filter have characteristics as shown in FIG. 12 if they are provided on the entire surface of the dot, and those shown in FIGS. 16 and 18 depending on the proportion if they are provided on a part of the dots. Make it.
[0139]
By providing the color filter on the outside of 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 attached later. In particular, by providing a color filter only at a part of the dots, there is an advantage that the assembly margin is expanded and the viewing angle is widened.
[0140]
(Example 27)
In Example 27, a non-linear element is provided corresponding to each dot on the inner surface of the substrate located on the reflector side of the pair of substrates. The structure of the reflective color liquid crystal device in this example is the same as that of FIG. 1 of Example 1, FIG. 6 of Example 6, and FIG. 8 of Example 7. The feature is that MIM elements 111, 611, and 811 are provided on the substrates 104, 604, and 804 located on the reflector side. By disposing in this way, unnecessary surface reflection is reduced and high contrast is obtained as compared with the reverse groove formation, that is, when the MIM element is provided on the substrates 102, 602, and 802. There are three reasons for this. One is that the reflection by the signal lines 109, 609, and 809 and the MIM element is partially absorbed by the color filters 107, 607, and 807, and the second is that the signal line itself has metal Cr stacked on metal Ta. The structure is that the reflectance of Cr is smaller than that of Ta. The third is that absorption due to birefringence interference occurs when reflected light passes through the liquid crystal layers 103, 603, and 803.
[0141]
(Example 28)
In Example 28, a nonlinear 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 that of FIG. The feature is in the wiring method of the MIM element.
[0142]
FIG. 43 is a diagram illustrating a wiring method of MIM elements of the reflective color liquid crystal device in Example 28. Reference numeral 4301 denotes a signal line, 4302 denotes an MIM element, and 4303 denotes a pixel electrode. Since the pixel electrodes respectively correspond to the red, green, and blue color filters on the counter substrate, the corresponding relationship is indicated by “R”, “G”, and “B” on the pixel electrode.
[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 found in data displays for personal computers. At this time, the signal line is wired parallel to the short side of the dot, that is, in the horizontal direction. Wiring in this way has the effect of reducing the number of wires and increasing the aperture ratio. Here, the aperture ratio is a ratio occupied by an area 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. Reference numeral 4401 denotes a signal line, 4402 denotes an MIM element, and 4403 denotes 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 to the long sides of the dots, that is, in the vertical direction. When wiring is performed in this manner, the number of wirings is three times that in the case of FIG. 43 and the aperture ratio is low. The reason why such wiring has been performed in the past is because the distance of the vertical wiring is shorter in the horizontally long panel, and the other is horizontal if the black mask is provided. This is because the aperture ratio does not change even when wiring is performed.
[0145]
As the aperture ratio increases, the display becomes brighter. Examples 23 to 25 have already explained in detail that the aperture ratio has an effect on the brightness, and that it is particularly prominent in the reflection type configuration with parallax.
[0146]
(Example 29)
In Example 29, the drive 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 driving area ratio and the contrast and the driving area ratio and the reflectance when the driving area ratio is changed from 50% to 100% with the same configuration as that of the second embodiment is shown. Here, the drive area ratio is defined as the ratio of the area where the liquid crystal is driven in the area excluding opaque portions such as metal wirings and MIM elements in the pixel. The horizontal axis represents the drive area ratio, 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 in the 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 drive 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 can be obtained in cyan display.
[0148]
(Example 30)
In the reflective color liquid crystal device, the characteristics of the scattering reflector greatly affect the 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 to have a low scattering property with emphasis on contrast and contrast.
[0149]
46 and 47 are diagrams showing the characteristics of the reflection plate of the reflective color liquid crystal device in Example 30 of the present invention. The reflector has a scattering characteristic such that when beam light is incident thereon, 80% or more of light is reflected in a 30 ° cone centered on the regular reflection direction.
[0150]
In FIG. 46, 4604 is a scattering reflection plate, 4601 is light incident on the scattering reflection plate surface at an angle of 45 °, 4602 is its regular reflection light, and 4603 is a 30 ° 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 incident light is reflected in the 30 ° cone of FIG. When this is less than 80%, a contrast ratio of 1:10 or more cannot be obtained under a normal indoor environment.
[0151]
For reference, FIG. 48 shows the result of computer simulation. The horizontal axis in the figure is the ratio of the light reflected in the 30 degree cone shown in FIG. 46, and the vertical axis in the figure is the brightness and contrast ratio. Assuming perfectly scattered white light like an integrating sphere as the light source, the light reflected in the normal direction of the substrate was calculated. The brightness of the standard white plate was 100%. As is clear from this simulation result, a brighter and higher-contrast display can be obtained as the proportion of the light reflected into the 30 ° cone increases, that is, as the scattering degree of the reflector decreases. However, it has been experimentally confirmed that a reflector that reflects light larger than 95% of incident light into a 30-degree cone has a very narrow viewing angle characteristic and cannot withstand practical use.
[0152]
(Example 31)
FIG. 49 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 31 of the invention. The reflecting plate is a semi-transmissive reflecting plate, and has a backlight on the back surface. First, the configuration will be described. Reference numeral 4901 denotes an upper polarizing plate, 4902 denotes a counter substrate, 4903 denotes a liquid crystal, 4904 denotes an element substrate, 4905 denotes a lower polarizing plate, 4906 denotes a transflective plate, 4912 denotes a backlight, and a color filter 4907 is provided on the counter substrate 4902. In addition, a counter electrode (scanning line) 4908 is provided, 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 characteristic as that of FIG.
[0153]
Since the reflectance of the transflective reflector is about 70% of that of a normal scattering reflector, the reflectance during white display is about 24% when used in the reflective mode without turning on the backlight. Become. On the other hand, in the transmission mode in which the backlight is turned on, the transmittance is about 22% and the surface brightness is 400 cd / m. ² Sufficient brightness can be obtained even with a monochrome backlight. In addition, the characteristics of the color filter as shown in FIG. 3 are not sufficient for displaying colors by transmission, but when a transflective plate is used, the color purity is increased by reflection of ambient light even in the transmission mode. effective.
[0154]
In order to obtain a bright display, it is desirable that the transflective plate reflects 80% or more of incident light. Inevitably, the display becomes dark when used in the transmissive mode, but pursuing the brightness of the transmissive mode tends to cause unsatisfactory results for both transmissive display and reflective display. If the transmission mode should be barely visible in the dark, you can get a good display that is more acceptable to the market.
[0155]
(Example 32)
In Example 32, the liquid crystal is a nematic liquid crystal twisted approximately 90 degrees, and two polarizing plates are arranged so that their transmission axes are orthogonal to the rubbing direction of the adjacent substrates. The basic configuration of the reflective color liquid crystal device in this embodiment and the spectral characteristics of the color filter 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 the relationship between the axes of the reflective color liquid crystal device in Example 32. In FIG. Reference numeral 5021 denotes a horizontal direction (longitudinal direction) of the liquid crystal panel, 5001 is a transmission axis direction of the upper polarizing plate, 5002 is a rubbing direction of the counter substrate positioned on the upper side, 5003 is a rubbing direction of the element substrate positioned on the lower side, 5004 Is the transmission axis direction of the lower polarizing plate. Here, the angle 5011 formed by the rubbing direction of the counter substrate and the horizontal direction of the liquid crystal panel is 45 °, the angle 5012 formed by the transmission axis direction of the upper polarizing plate and the rubbing direction of the counter substrate is 90 °, and the twist angle 5013 of the liquid crystal is set. The angle 5014 formed by 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, molecules at the center of the liquid crystal layer rise from the observer side (ie, the lower side in the figure) when a voltage is applied, and in combination with the viewing angle characteristics of the TN liquid crystal, display with high contrast and less visible shadows becomes possible. In addition, an 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 color change due to the viewing angle direction is less than that in a parallel arrangement (so-called E mode).
[0157]
Further, 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. 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 liquid crystal layer thickness d 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 of FIG. 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. In FIG. Reference numeral 5021 denotes a horizontal direction (longitudinal direction) of the liquid crystal panel, 5001 is a transmission axis direction of the upper polarizing plate, 5002 is a rubbing direction of the counter substrate positioned on the upper side, 5003 is a rubbing direction of the element substrate positioned on the lower side, 5004 Is the transmission axis direction of the lower polarizing plate. Here, the angle 5011 formed by the rubbing direction of the counter substrate and the horizontal direction of the liquid crystal panel is 45 °, the angle 5012 formed by the transmission axis direction of the upper polarizing plate and the rubbing direction of the counter substrate is 90 °, and the twist angle 5013 of the liquid crystal is set. The angle 5014 formed by 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, molecules at the center of the liquid crystal layer rise from the observer side (ie, the lower side in the figure) when a voltage is applied, and in combination with the viewing angle characteristics of the TN liquid crystal, display with high contrast and less visible shadows becomes possible. In addition, an 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 color change due to the viewing angle direction is less than that in a parallel arrangement (so-called E mode).
[0160]
Here, a birefringence Δn of the liquid crystal material was set to 0.084, and a cell gap was changed to produce a panel having a different Δn × d.
[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 of the example, and 5102 denotes the reflectance for each Δn × d of the comparative example. For the measurement, an integrating sphere was used so that light was incident uniformly from all directions. The reflectance was taken as 100% of a standard white plate. As can be seen from FIG. 51, as Δn × d increases, the viewing angle narrows and the utilization efficiency of incident light from an oblique direction decreases, so that the display becomes dark. Therefore, in order 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 color is large. For this reason, the conventional reflection type monochrome liquid crystal device uses a condition where Δn × d is large as in the thirty-second embodiment. However, in the reflection type color liquid crystal device, a little 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 color was obtained.
[0162]
The highest reflectance is exhibited when Δn × d is 0.42 μm. The reflectance corresponding to Δn × d in the vicinity thereof is shown in Table 3 below.
[Table 3]

[0163]
Thus, a bright display can be obtained by making Δn × d larger than 0.34 μm and smaller than 0.52 μm.
[0164]
When Δn × d is smaller than 0.40 μm, a bright display is obtained due to the wide viewing angle, but on the other hand, since the brightness in the front direction is low and it looks dark under a spot light source, Δn × d is 0.40 μm or more is preferable. Moreover, since extremely large coloring can be eliminated by setting it to 0.48 μm or less, 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 is a nematic liquid crystal twisted by 90 degrees or more, and two polarizing plates and at least one retardation film are arranged. FIG. 52 is a diagram showing a main part of the reflective color liquid crystal device in Example 34. In FIG. First, the configuration will be described. 5201 is an upper polarizing plate, 5202 is a retardation 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 placed on the upper substrate 5203. 5208 and a scanning electrode 5209 are provided, and a signal electrode 5210 is provided on 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 characteristic as that of FIG.
[0166]
FIG. 53 is a diagram showing the relationship between the axes of the reflective color liquid crystal device in Example 34. In FIG. 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. A direction 5305 is a stretching direction of the retardation film. Here, the angle 5311 formed by the rubbing direction of the upper substrate and the horizontal direction of the liquid crystal panel is 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 54 °. The angle 5315 formed by the direction of the upper substrate and the rubbing direction of the upper substrate is 80 °, the twist angle 5312 of the liquid crystal is 240 ° to the left, and the angle 5313 formed by the transmission axis direction of the lower polarizing plate and the rubbing direction of the lower substrate is 43 °. Set. With this arrangement, the molecule at the center of the liquid crystal layer rises from the viewer side (ie, the lower side in the figure) when a voltage is applied, and in combination with the viewing angle characteristics, a display with high contrast and less visible shadows becomes possible.
[0167]
This is a retardation 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. Despite the use of the same color filter as in the second embodiment, the aperture ratio is as high as the signal line and MIM element are unnecessary, and the reflectance during white display is 33%, enabling a very bright display. . Although the contrast ratio was relatively low at 1: 8, the number of retardation films for color compensation was increased by one, and multi-line simultaneous selection driving was performed according to the method disclosed in Japanese Patent Laid-Open No. 6-348230. The same color can be displayed with the same contrast as when the MIM element is provided.
[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 showing a main part of the structure of the reflective color liquid crystal device in Example 35. In FIG. 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 reflection plate, and a color filter is provided on the upper substrate 5503. 5508 and a scanning electrode 5509 are provided, and a signal electrode 5510 is provided on the lower substrate 5505. The retardation film 5502 is a uniaxially stretched film of polycarbonate and has a positive retardation of 587 nm. The product Δn × d of Δn and cell gap of the liquid crystal is 0.85 μm.
[0169]
FIG. 53 is a diagram illustrating the relationship between the axes of the reflective color liquid crystal device in Example 35. In FIG. 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. A direction 5305 is a stretching direction of the retardation film. Here, the angle 5311 formed by the rubbing direction of the upper substrate and the horizontal direction of the liquid crystal panel is 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 38 °. The angle 5315 formed by the direction of the upper substrate and the rubbing direction of the upper substrate is 92 °, the twist angle 5312 of the liquid crystal is 240 ° to the left, and the angle 5313 formed by 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 showing the spectral characteristics of the color filters of the reflective color liquid crystal device in Example 35. In FIG. In FIG. 54, the horizontal axis represents the light wavelength, the vertical axis represents the transmittance, 5401 represents the spectrum of the red filter, 5402 represents the spectrum of the green filter, and 5403 represents the spectrum of the blue filter. This color filter characteristic is optimized so as to achieve white balance from the spectral characteristic 5411 in the off state when the color filter is removed from the liquid crystal device. Here, the green filter and the blue filter have a transmittance of 50% or more in the wavelength range of 450 nm to 660 nm. Further, the minimum transmittance of the red filter for light having a wavelength in the range of 450 nm to 660 nm is clearly smaller than that of the blue filter and the green filter. By using such a red filter, the most appealing red color can be displayed vividly. In addition, the blue filter spectrum 5403 was made close to cyan for the purpose of compensating for the darkening of red.
[0171]
This is a retardation 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 retardation plate compensation type STN mode, although it was possible to perform black and white display, it was possible to produce only a cyan-like white. However, the reflective color liquid crystal device of Example 35 can display white that is much more neutral than before by optimizing the color filter. Even though a color filter having characteristics similar to those of the ninth embodiment is used, the aperture ratio is high as much as signal lines and MIM elements are unnecessary, and the reflectance during white display is 29%, which is very bright. Is possible.
[0172]
(Example 36)
In Example 36 of the present invention, a reflecting plate was provided between a pair of substrates, and only one polarizing plate was disposed. FIG. 56 is a diagram showing a main part of the reflective color liquid crystal device in Example 36. In FIG. First, the configuration will be described. Reference numeral 5601 denotes an upper polarizing plate, 5602 denotes a counter substrate, 5603 denotes a liquid crystal, and 5604 denotes 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 which also serves as a scattering reflector, and an MIM element 5609 are provided. The pixel electrode that also serves as the scattering reflector was a surface of a sputtered metal aluminum film that was roughened by mechanical and chemical techniques. Further, the color filter has the same spectral characteristic as that of FIG.
[0173]
FIG. 57 is a diagram illustrating the relationship between the axes of the reflective color liquid crystal device in Example 36. In FIG. Reference numeral 5721 denotes the horizontal direction (longitudinal direction) of the liquid crystal panel, 5701 is the transmission axis direction of the upper polarizing plate, 5702 is the rubbing direction of the upper substrate, and 5703 is the rubbing direction of the lower substrate. Here, the angle 5711 formed by the rubbing direction of the upper substrate and the horizontal direction of the liquid crystal panel is 62 °, the angle 5712 formed by the transmission axis direction of the upper polarizing plate and the rubbing direction of the upper substrate is 94 °, and the twist angle 5713 of the liquid crystal is set. Set to 56 ° to the right. With this arrangement, molecules at the center of the liquid crystal layer rise from the observer side (ie, the lower side in the figure) when a voltage is applied, and high contrast display is possible in combination with viewing angle characteristics.
[0174]
This is a single polarizing plate type nematic liquid crystal mode proposed in Japanese Patent Application Laid-Open No. Hei 3-223715, and can display black and white with high contrast without using a lower polarizing plate. It is characterized in that a reflector can be provided.
[0175]
This reflective color liquid crystal device has a reflectance of 30% when displaying white, 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 in the display, and the viewing angle dependency is very small. Further, for example, since light incident through the red filter is always emitted through the red filter, color turbidity does not occur, and a bright and high-purity display can be 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 the main part of the structure when a reflective color liquid crystal device of the present invention in which a reflective plate is provided between a pair of substrates and only one polarizing plate is arranged using a TFT element. First, the configuration will be described. Reference numeral 5801 denotes an upper polarizing plate, 5802 denotes a counter substrate, 5803 denotes a liquid crystal, and 5804 denotes an element substrate. A color filter 5805 and a counter electrode (common electrode) 5806 are provided on the counter substrate 5802, and a gate is provided on the element substrate 5804. A pixel electrode 5810 serving also as a signal line 5807, a source signal line 5808, a TFT element 5809, and a scattering reflector is provided. In the case of the MIM element, the metal wiring only runs in the vertical direction, but in the TFT element, the metal wiring runs in the vertical direction and the horizontal direction, so that the aperture ratio decreases. Fortunately, this Example 36 does not require a lower polarizing plate. Therefore, when using a TFT element, it is preferable to provide a method of providing an insulating film on the element and signal line layer, providing a reflective plate also serving as a pixel electrode on the layer, and connecting the two through a contact hole.
[0177]
(Example 37)
Example 37 is a reflective color liquid crystal device in which a reflective plate is provided between a pair of substrates and only one polarizing plate is disposed, and the reflective plate is a specular reflective plate, and the outer surface of the substrate located on the incident light side First, six examples relating to a reflective monochrome liquid crystal device will be introduced. Any 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 reflective liquid crystal device in the first example. First, the configuration will be described. 590l 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 the absorption axes of the polarizing plates 5902 and 5908 are TN modes that 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 5905 and the birefringence Δn is 0.48 μm.
[0179]
The reflection type liquid crystal device having the above configuration has a brightness of 25% and a contrast of 1:15 when displaying white in the normal direction of the substrate indoors, and brightness of white display in the regular reflection direction of the ceiling lamp. Was 45% and the contrast was 1:12. Even in the regular reflection direction, the ceiling light is not reflected due to the backscattering effect of the scattering plate, and high contrast can be obtained. As described above, since the light in the regular reflection direction can be used effectively while maintaining a sufficient contrast, a very bright display can be obtained.
[0180]
<Second example>
60 shows a reflection type liquid crystal device No. 2 in the second example. 1 to No. 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]
61 shows a reflection type liquid crystal device No. 2 in the second example. 1 to No. 3 shows the axial direction of the polarizing plate 3 and the like. Reference numeral 6101 denotes a transmission axis direction of the upper polarizing plate 6002, 6103 denotes a rubbing direction of the upper substrate 6003, 6103 denotes a rubbing direction of the lower substrate 6007, and 6104 denotes an angle θ 1 formed horizontally with the transmission axis direction 6101 of the upper polarizing plate 6002. Reference numeral 6105 denotes an angle θ2 formed horizontally with the rubbing direction 6102 of the upper substrate 6003, and reference numeral 6106 represents an angle θ3 formed horizontally with the rubbing direction 6103 of the lower substrate 6007. The angle is positive in the counterclockwise direction and is shown as -180 degrees to 180 degrees.
[0182]
62 shows a reflection type liquid crystal device No. 2 in the second example. 4 to No. 6 is a cross-sectional view of FIG. 6201 is a scattering plate, 6202 is an upper polarizing plate, 6203 is a retardation 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]
63 shows a reflection type liquid crystal device No. 2 in the second example. 4 to No. 6 shows the axial direction of the 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 retardation 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. Angles θ1 and 6306 formed horizontally in the transmission axis direction 6301 of the substrate 6204 are angles θ2 and 6307 formed horizontally in the rubbing direction 6303 of the upper substrate 6204, and angles θ3 and 6308 formed horizontally in the rubbing direction 6304 of the lower substrate 6208 are retardation plates. 6203 is an 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 retardation value of the retardation plate. In the figure, Δn × d and the unit of phase difference are μm.
[Table 4]

[0185]
These characteristics 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 the first example and the second example>
FIG. 64 is a cross-sectional view of a reflective liquid crystal device in a comparative example. Reference numeral 6401 denotes an upper polarizing plate, 6402 denotes an upper substrate, 6403 denotes an upper electrode, 6404 denotes a liquid crystal, 6405 denotes a lower electrode, 6406 denotes a lower substrate, 6407 denotes a lower polarizing plate, and 6408 denotes a scattering reflector. The liquid crystal 6404 is twisted by 90 degrees in the cell as in the first example, and the absorption axes of the polarizing plates 6401 and 6407 are TN modes that 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 6404 and the birefringence Δn is 0.48 μm.
[0187]
In the reflection type liquid crystal device having the above configuration, the brightness when displaying white in the normal direction of the substrate is 28% and the contrast is 1:15 in the room, but the reflection of the ceiling lamp is in the regular reflection direction of the ceiling lamp. Therefore, 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 the characteristics of the scattering plate of the reflective liquid crystal device in the third example. In FIG. 65, reference numeral 6501 denotes a scattering plate, reference numeral 6502 denotes incident light, reference numeral 6503 denotes specular reflection light, and reference numeral 6504 denotes a 10 degree cone centered on the specular reflection light 6503. The scattering plate 6501 of the third example scatters 5% of incident light into the 10 degree cone 6503.
[0189]
The scattering plate having the above characteristics creates forward scattering by mixing particles having a refractive index different from that of the medium, and adjusts the back scattering by providing minute irregularities on the surface, as described in EID95-146. I got it. When the scattered light is larger than 10%, the reflection of the light source is increased and the contrast is lowered. Conversely, when the scattered light is smaller than 0.5%, the display blur is excessively increased.
[0190]
The configuration of this example is the same as the configuration shown in FIG. 59 of the first example, the liquid crystal 5905 is twisted 90 degrees in the cell, and the absorption axes of the polarizing plates 5902 and 5908 are close to each other. The TN mode coincides with 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 when displaying white in the normal direction of the substrate indoors, and brightness of white display in the regular reflection direction of the ceiling lamp. 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 configuration of FIGS. 60 and 62 of the second example.
[0193]
Each axial direction shown in FIGS. 61 and 63, Δn × d and phase difference of the liquid crystal 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, sufficient contrast and bright display can be obtained.
[0194]
<Fifth example>
FIG. 66 is a cross-sectional view of the reflective liquid crystal device in the fifth example. First, the configuration will be described. Reference numeral 6601 denotes a scattering plate, 6602 denotes an upper polarizer, 6603 denotes an upper substrate, 6604 denotes an upper electrode, 6605 denotes a liquid crystal, 6606 denotes a lower polarizer, 6607 denotes a lower electrode / specular reflector, and 6608 denotes a lower substrate. The liquid crystal 6605 is twisted by 90 degrees in the cell, and the absorption axes of the polarizing plates 6602 and 6606 are TN modes that 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 vapor-deposited on the lower electrode, and the polarizing plate was obtained by applying and aligning a liquid crystalline polymer solution containing a black dichroic dye on a polyimide alignment film. The same scattering plate as in the third example was used.
[0195]
The reflection type liquid crystal device having the above configuration has a brightness of 28% when displaying white in the substrate normal direction and a contrast of 1:18 indoors, and the brightness of white display in the regular reflection direction of the ceiling lamp. 44% and contrast was 1:16.
[0196]
<Sixth example>
67 shows a reflection type liquid crystal device No. 6 in the sixth example. 1 to No. FIG. Reference numeral 6701 denotes a scattering plate, 6702 denotes an upper polarizing plate, 6703 denotes an upper substrate, 6704 denotes an upper electrode, 6705 denotes a liquid crystal, 6706 denotes a lower electrode / specular reflector, and 6707 denotes a lower substrate.
[0197]
61 shows a reflection type liquid crystal device No. 6 in the sixth example. 1 to No. 3 shows the axial direction of the polarizing plate 3 and the like. Reference numeral 6101 denotes a transmission axis direction of the upper polarizing plate 6002, 6103 denotes a rubbing direction of the upper substrate 6003, 6103 denotes a rubbing direction of the lower substrate 6007, and 6104 denotes an angle θ 1 formed horizontally with the transmission axis direction 6101 of the upper polarizing plate 6002. Reference numeral 6105 denotes an angle θ2 formed horizontally with the rubbing direction 6102 of the upper substrate 6003, and reference numeral 6106 represents an angle θ3 formed horizontally with the rubbing direction 6103 of the lower substrate 6007.
[0198]
68 shows a reflection type liquid crystal device No. 6 in the sixth example. 4 to No. 6 is a cross-sectional view of FIG. Reference numeral 6801 denotes a scattering plate, 6802 denotes an upper polarizing plate, 6803 denotes a retardation plate, 6804 upper substrate, 6805 denotes an upper electrode, 6806 denotes liquid crystal, 6807 denotes a lower electrode / specular reflector, and 6808 denotes a lower substrate.
[0199]
63 shows a reflection type liquid crystal device No. 6 in the sixth example. 4 to No. 6 shows the axial direction of the 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 retardation 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. Angles θ1 and 6306 formed horizontally in the transmission axis direction 6301 of the substrate 6204 are angles θ2 and 6307 formed horizontally in the rubbing direction 6303 of the upper substrate 6204, and angles θ3 and 6308 formed horizontally in the rubbing direction 6304 of the lower substrate 6208 are retardation plates. 6203 is an angle θ4 formed with the horizontal in the slow axis direction 6302.
[0200]
The conditions for 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 scattering plate was the same as that in the third example.
[0201]
Table 7 below shows the characteristics of the reflective liquid crystal display device having the above-described configuration.
[Table 7]

In both cases, sufficient contrast and bright display can be obtained.
[0202]
Any 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 the reflective color liquid crystal device in Example 37 of the invention. Reference numeral 6901 denotes a scattering plate, 6902 denotes an upper polarizing plate, 6903 denotes a retardation plate, 6904 denotes an upper substrate, 6905 denotes a liquid crystal, 6906 denotes a lower substrate, 6907 denotes a counter electrode (scanning line), 6908 denotes a signal line, and 6909 denotes a pixel electrode. A mirror reflector, 6910 is an MIM element, and 6911 is a color filter. The distance between the pixels was 160 μm in both directions orthogonal to and parallel to the signal line, the width of the signal line was 10 μm, the gap between the signal line and the pixel electrode was 10 μm, and the distance between the adjacent pixel electrode and the pixel electrode was 10 μm.
[0204]
FIG. 63 shows the axial direction of the polarizing plate or the like. 6301 is the transmission axis direction of the upper polarizing plate 6202, 6302 is the slow axis direction of the retardation 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. Angles θ1 and 6306 formed horizontally with the transmission axis direction 6301 of the substrate are angle θ2 and 6307 formed horizontally with the rubbing direction 6303 of the upper substrate 6204 and angles θ3 and 6308 formed horizontally with the rubbing direction 6304 of the lower substrate 6208 are retardation plates. 6203 is an angle θ4 formed with the horizontal in the slow axis direction 6302.
[0205]
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 / specular reflector 6909.
[0206]
The same scattering plate as in the third example was used. As the color filter 6911, cyan (C in the figure) and red (R in the figure) color filters having an average transmittance of 75% were used.
[0207]
The reflection type liquid crystal device having the above configuration has a brightness of 30% and a contrast of 1:15 when displaying white in the normal direction of the substrate indoors, and brightness of white display in the regular reflection direction of the ceiling lamp. Was 51% and the contrast was 1:12. In all cases, the display colors were x = 0.39 and y = 0.32 for red, x = 0.28 for cyan, and y = 0.31. The color can be recognized sufficiently and the display is bright.
[0208]
(Example 38)
Example 38 is a reflection type color liquid crystal device comprising a reflection plate between a pair of substrates and a single polarizing plate, or the reflection plate is a specular reflection plate and incident light. 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 also related to the reflective color liquid crystal device in the same manner as the liquid crystal in the pixel portion. First, two examples related to the reflective type monochrome liquid crystal device will be introduced. Any 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 reflective 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 specular 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 90 degrees in the cell, and the absorption axes of the polarizing plates 7002 and 7006 are TN modes that coincide with the slow axis of the liquid crystal 7004 at the adjacent 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 in the third example of Example 37 was used.
[0210]
The distance between the pixels was 160 μm in both directions orthogonal to and parallel to the signal line, the width of the signal line was 10 μm, the gap between the signal line and the pixel electrode was 10 μm, and the distance between the adjacent pixel electrode and the pixel electrode was 10 μm.
[0211]
In the reflective liquid crystal device having the above structure, the regions other than the pixel portion of the signal line 7009 and the counter electrode 7008 are rubbed in the same manner as the region on the pixel electrode 7010 to arrange the liquid crystal. The brightness when displaying white in the line direction was 23% and the contrast was 1:14, and the brightness of white display in the regular reflection direction of the ceiling lamp was 43% and the contrast was 1:11.
[0212]
By the way, since the paintability on the metal electrode is different from that of ITO of the pixel electrode, it is often repelled even if an alignment film is applied. In such a case, that is, when the orientation process is not performed on the signal line 7009, the brightness when displaying white in the normal direction of the substrate in the room is 19% and the contrast is 1:14, and the regular reflection direction of the ceiling lamp The white display brightness was 40% and the contrast was 1:11.
[0213]
In either case, a high contrast and a very bright display can be obtained, but a brighter display can be obtained by orienting the metal wiring.
[0214]
<Second example>
71 shows a reflection type liquid crystal device No. 2 in the second example. 1 and No. FIG. Reference numeral 7101 denotes a scattering plate, 7102 denotes an upper polarizing plate, 7103 denotes an upper substrate, 7104 denotes a liquid crystal, 7105 denotes a lower substrate, 7106 denotes a specular reflector, 7107 denotes a counter electrode (scanning line), 7108 denotes a signal line, and 7109 denotes a pixel electrode. , 7110 are MIM elements. The distance between the pixels was 160 μm in both directions orthogonal to and parallel to the signal line, the width of the signal line was 10 μm, the gap between the signal line and the pixel electrode was 10 μm, and the distance between the adjacent pixel electrode and the pixel electrode was 10 μm.
[0215]
61 shows a reflection type liquid crystal device No. 2 in the second example. 1 to No. 3 shows the axial direction of the polarizing plate 3 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 horizontally with the transmission axis direction 6101 of the upper polarizing plate 6002. Reference numeral 6105 denotes an angle θ2 formed horizontally with the rubbing direction 6102 of the upper substrate 6003, and reference numeral 6106 represents an angle θ3 formed horizontally with the rubbing direction 6103 of the lower substrate 6007.
[0216]
72 shows the reflection type liquid crystal device No. 2 in the second example. 2 and No. FIG. 7201 is a scattering plate, 7202 is a retardation 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 specular reflection plate, 7208 is a counter electrode (scanning line), and 7209 is a signal. Reference numeral 7210 denotes a pixel electrode, and 7211 denotes an MIM element. The distance between the pixels was 160 μm in both directions orthogonal to and parallel to the signal line, the width of the signal line was 10 μm, the gap between the signal line and the pixel electrode was 10 μm, and the distance between the adjacent pixel electrode and the pixel electrode was 10 μm.
[0217]
63 shows a reflection type liquid crystal device No. 2 in the second example. 4 to No. 6 shows the axial direction of the 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 retardation 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. Angles θ1 and 6306 formed horizontally in the transmission axis direction 6301 of the substrate 6204 are angles θ2 and 6307 formed horizontally in the rubbing direction 6303 of the upper substrate 6204, and angles θ3 and 6308 formed horizontally in the rubbing direction 6304 of the lower substrate 6208 are retardation plates. 6203 is an angle θ4 formed with the horizontal in the slow axis direction 6302.
[0218]
The same scattering plate as in the third example of Example 37 was used.
In the reflection type liquid crystal device having the above-described structure, 1 and No. No. 2 is obtained by subjecting the region other than the pixel portion to orientation treatment. 3 and no. In the case of No. 4, only the pixel portion was subjected to an alignment process.
[0219]
Table 8 below shows Δn × d of the liquid crystal 7205, the angle of the polarizing plate, and the retardation of the retardation plate.
[Table 8]

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

[0221]
In any of the examples, a bright display with high contrast can be obtained, but a brighter display can be obtained by applying an alignment process to a region other than the pixel portion.
[0222]
(Example 39)
Example 39 relates to a reflective color liquid crystal device whose display is a normally white type. First, an example related 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]
59 shows a reflection type liquid crystal device No. 1, no. 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 90 degrees in the cell. 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 the 5908 coincide with the slow axis of the liquid crystal 5905 at the adjacent interface. 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 in the third example of Example 37 was used.
[0224]
FIG. 73 is a graph showing voltage transmittance characteristics of the reflective liquid crystal device of Example 37. In FIG. Here, 7301 is No. 1 is a change in transmittance with respect to the voltage of 1. 2 shows a change in transmittance with respect to a voltage of 2. FIG. No. 1 is normally white, no. 2 is a display of normally black.
[0225]
The reflection type liquid crystal device having the above structure is No. In the room 1, 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 lamp is 45%, and the contrast is 1: It was 12. No. In the room 2, the white display brightness in the normal direction of the substrate is 23% and the contrast is 1:15, the white display brightness in the regular reflection direction of the ceiling lamp is 42%, and the contrast is 1: 13.
[0226]
Both provide sufficient contrast and bright display, but the normally white mode provides brighter display. This is because the area outside the pixel contributes to the brightness, and it has a viewing angle characteristic that easily transmits light incident from an oblique direction.
[0227]
(Example 40)
When displaying with the reflection type color liquid crystal device in the above-described Examples 1 to 39, there arises a problem that does not exist in the conventional transmission type color liquid crystal device. That is, a single dot does not produce sufficient color, and in order to display a color, it is necessary to display the same color over a certain wide area. This is due to the fact that the color of the color filter is light, the distance between the liquid crystal layer and the reflecting plate is long (except for Examples 36 to 39), and the colors of adjacent dots are likely to be mixed.
[0228]
Therefore, rather than displaying red characters on a white background, using black characters on a white background and making a part of the background red, that is, using a marker is more suitable. However, the fact that a single pixel does not sufficiently develop color means that, on the contrary, it is possible to easily perform black and white display even though it is a color liquid crystal device.
[0229]
The reflective color liquid crystal device of Example 40 is characterized in that one pixel is constituted by one dot. A pixel is a minimum unit capable of realizing a function required for display. In a normal color liquid crystal device, one pixel is composed of 3 dots in total, each of red, green, and blue. Accordingly, 480 × 640 × 3 dots are necessary to display a VGA with 480 × 640 pixels. When using two color filters of cyan and red, 480 × 640 × 2 dots were necessary. However, Example 40 can perform VGA display with 480 × 640 pixels even though it is a color liquid crystal device.
[0230]
The configuration of the fortieth embodiment is the same as that of the fifth embodiment, for example. However, the following measures should be taken when displaying. An example is shown in FIG. 74, which will be described with reference to this figure. Here, 16 × 48 pixels are illustrated. (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. (B) and (c) are diagrams showing the distribution of on dots and off dots. Since the on-dot is a dark display, it is indicated by hatching. The display in (b) is turned on in the form of “LCD” ignoring the color filter arrangement. However, as described above, this reflective color liquid crystal device does not sufficiently develop color with a single dot. , "LCD" appears black on a white background. Therefore, monochrome display is possible with VGA resolution. On the other hand, the display of (c) is the one 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. Thus, when the same color is displayed over an area of 10 dots or wider, it is possible to display the color.
[0231]
In addition to such usage 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. In addition, since the icons 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 for electronic devices.
[0233]
FIG. 75 is a diagram illustrating an example of an electronic apparatus that employs the reflective color liquid crystal device according to the first to the forty embodiments. This is a so-called PDA (Personal Digital Assistant), which is a kind of portable information terminal. 7501 is a reflective color liquid crystal device, and a tablet for pen input is mounted on the front surface thereof. Conventionally, a reflective monochrome liquid crystal device or a transmissive color liquid crystal device has been used for a PDA display. Replacing these with a reflective color liquid crystal device has the advantage of a dramatic increase in the amount of information by color display compared to the former, and the advantages of longer battery life and smaller size and weight than the latter.
[0234]
FIG. 76 is a diagram illustrating an example of an electronic device attached so that the display unit can be moved with respect to the main body so that ambient light can be efficiently reflected by an observer in the electronic device of Example 41. This is a so-called digital still camera. Reference numeral 7601 denotes a reflective color liquid crystal device which is attached so that its angle can be changed with respect to the main body. Although not shown, the lens is on the back side of the reflection type color liquid crystal device mounting portion. Conventionally, a transmissive color liquid crystal device has been used for a display for a digital still camera. By replacing this with a reflective color liquid crystal device, not only the battery life and size were reduced, but also the visibility under direct sunlight was greatly improved. This is because, since the brightness of the backlight is limited in the transmissive color liquid crystal device, it becomes difficult to see when the surface reflection increases under direct sunlight, but the display of the reflective color liquid crystal device becomes brighter as the ambient light becomes brighter. It is. In order to effectively use the 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-mentioned electronic devices, the reflective color liquid crystal device is a variety of devices that place importance on portability, such as palmtop PCs, sub-notebook PCs, notebook PCs, handy terminals, camcorders, liquid crystal televisions, game machines, electronic notebooks, mobile phones, pagers Applicable to electronic devices.
[Brief description of the drawings]
FIG. 1 is a diagram showing a main part of a structure of a reflective 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 Embodiment 1 of the present invention.
FIG. 3 is a diagram illustrating spectral characteristics of a color filter 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 graph plotting changes in contrast when the thickness of an element substrate is changed in a reflective color liquid crystal device in Example 3 of the present invention.
FIG. 5 is a diagram showing spectral characteristics of a color filter of a reflective type color liquid crystal device in Example 4 of the present invention.
FIG. 6 is a diagram showing a main part of the structure of a reflective color liquid crystal device in Examples 5, 6, 23, 27, 32, and 40 of the present invention.
FIG. 7 is a diagram showing spectral characteristics of a color filter of a reflective color liquid crystal device in Example 6 of the present invention.
FIG. 8 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Examples 7, 9, 24, 27, and 28 of the present invention.
FIG. 9 is a diagram showing spectral characteristics of a color filter of a reflective color liquid crystal device in Example 7 of the present invention.
FIG. 10 is a diagram showing a main part of the structure of a reflective color liquid crystal device in Embodiments 8 and 10 of the present invention.
FIG. 11 is a diagram showing spectral characteristics of a color filter of a reflective color liquid crystal device in Example 8 of the present invention.
FIG. 12 is a diagram illustrating spectral characteristics of color filters of a reflective color liquid crystal device according to Examples 9, 24, 25, and 26 of the present invention.
13 is a diagram illustrating spectral characteristics of a color filter of a reflective color liquid crystal device according to Example 10 of the present invention. FIG.
14 is a graph plotting changes in average transmittance when the thickness of a color filter is changed in the reflective color liquid crystal device in Example 10 of the present invention. FIG.
FIG. 15 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Examples 11, 12, and 15 of the present invention.
FIG. 16 is a diagram showing spectral characteristics of a color filter of a reflective color liquid crystal device in Examples 11, 21, and 26 of the present invention.
FIG. 17 is a graph plotting changes in average transmittance when the proportion of the area where a color filter is provided is changed in the reflective color liquid crystal device in Example 11 of the present invention.
FIG. 18 is a diagram illustrating spectral characteristics of a color filter of a reflective color liquid crystal device according to Examples 12 and 26 of the present invention.
FIG. 19 is a graph plotting changes in average transmittance when the ratio of the area where a color filter is provided is changed in the reflective color liquid crystal device in Example 12 of the present invention.
FIG. 20 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Examples 13 and 15 of the present invention.
FIG. 21 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Examples 14 and 15 of the invention.
FIG. 22 is a diagram showing voltage reflectance characteristics of a reflective color liquid crystal device in Example 15 of the present invention.
FIG. 23 is a diagram showing the structure of a color filter substrate of a reflective color liquid crystal device in Example 16 of the present invention.
FIG. 24 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 16 of the invention.
FIG. 25 is a diagram illustrating spectral characteristics of a color filter of a reflective color liquid crystal device according to Example 16 of the present invention.
FIG. 26 is a diagram showing average spectral characteristics within one dot of a color filter of a reflective type color liquid crystal device in Examples 16 and 17 of the present invention.
FIG. 27 is a diagram showing the structure of a color filter substrate of a reflective color liquid crystal device in a comparative example referred to in Example 16 of the present invention.
FIG. 28 is a diagram showing the structure of a color filter substrate of a reflective color liquid crystal device in Example 17 of the present invention.
FIG. 29 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. 30 is a diagram illustrating spectral characteristics of a color filter of a reflective color liquid crystal device in Example 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 the arrangement of color filters of a reflective color liquid crystal device in Example 18 of the present invention.
FIG. 33 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 21 of the invention.
FIG. 34 is a diagram showing the arrangement of color filters of a reflective color liquid crystal device in Example 21 of the present invention.
FIG. 35 is a diagram showing the arrangement of color filters of a reflective color liquid crystal device in Example 21 of the present invention.
FIG. 36 is a diagram showing the arrangement of color filters of a reflective color liquid crystal device in Example 21 of the present invention.
FIG. 37 is a diagram schematically showing the structure of a reflective color liquid crystal device in Example 22 of the invention.
FIG. 38 is a diagram showing the arrangement of color filters of a reflective color liquid crystal device in Example 23 of the present invention.
FIG. 39 is a diagram showing the arrangement of color filters of a reflective color liquid crystal device in Example 24 of the present invention.
FIG. 40 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 25 of the invention.
FIG. 41 is a diagram showing the arrangement of color filters of a reflective color liquid crystal device in Example 25 of the present invention.
FIG. 42 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 26 of the invention.
FIG. 43 is a diagram showing a wiring method of MIM elements of a reflective color liquid crystal device in Example 28 of the present invention.
44 is a diagram showing a wiring method of MIM elements of a reflective color liquid crystal device in a comparative example referred to in Example 28 of the present invention. FIG.
FIG. 45 is a graph plotting changes in contrast and reflectance when the drive area is changed in the reflective color liquid crystal device in Example 29 of the present invention.
FIG. 46 is a diagram for explaining the scattering characteristics of the reflecting plate of the reflective color liquid crystal device in Example 30 of the invention.
FIG. 47 is a diagram showing the scattering characteristics of the reflecting plate of the reflective 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 in a 30 degree cone is changed in the reflective color liquid crystal device in Example 30 of the present invention.
FIG. 49 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 31 of the invention.
FIG. 50 is a diagram showing the relationship between the axes of a reflective color liquid crystal device in Examples 32 and 33 of the present invention.
FIG. 51 is a graph plotting changes in white display reflectance when Δn × d of a liquid crystal cell is changed in the reflective color liquid crystal device in Example 33 of the present invention.
52 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 34 of the invention. FIG.
FIG. 53 is a diagram showing the relationship between axes of a reflective color liquid crystal device in 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 Embodiment 35 of the present invention.
FIG. 55 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 35 of the invention.
FIG. 56 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 36 of the invention.
FIG. 57 is a diagram showing the relationship between axes of a reflective color liquid crystal device in Example 36 of the present invention.
FIG. 58 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 36 of the invention.
FIG. 59 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Examples 37 and 39 of the invention.
FIG. 60 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 37 of the invention.
FIG. 61 is a diagram showing the 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 the main part of the structure of a reflective color liquid crystal device in Example 37 of the invention.
FIG. 63 is a diagram showing the relationship between axes of a reflective color liquid crystal device in Examples 37 and 38 of the present invention.
FIG. 64 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 37 of the invention.
FIG. 65 is a diagram showing the characteristics of the scattering plate of the reflective color liquid crystal device in Example 37 of the invention.
FIG. 66 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 37 of the invention.
FIG. 67 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 37 of the invention.
FIG. 68 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 37 of the invention.
FIG. 69 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 37 of the invention.
FIG. 70 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 38 of the invention.
71 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 38 of the present invention. FIG.
72 is a diagram showing the main part of the structure of a reflective color liquid crystal device in Example 38 of the present invention. FIG.
FIG. 73 is a diagram showing voltage transmittance characteristics of the reflective color liquid crystal device in Example 39 of the invention.
74 is a diagram showing an example of a display method of the reflective color liquid crystal device in Example 40 of the present invention. FIG.
75 is a diagram showing an example of an electronic apparatus using a reflective color liquid crystal device in Example 41 of the present invention. FIG.
FIG. 76 is a diagram showing an example of an electronic apparatus using a reflective color liquid crystal device in Example 41 of the present invention.
77 is a diagram illustrating a parallax problem peculiar to a reflective color liquid crystal device. FIG.
FIG. 78 is a diagram illustrating spectral characteristics of a color filter of a conventional transmissive color liquid crystal device.
Fig. 79: Fig. Of Tatsuo Uchida et al. (IEEE Transactions on Electron Devices, Vol. ED-33, No. 8, pp. 1207-1212 (1986)). FIG. 8 is a diagram illustrating spectral characteristics of a color filter proposed in FIG.
FIG. 80 is a copy of FIG. Of Seiichi Mitsui et al. (SID92 DIGEST, pp. 437-440 (1992)). 2 is a diagram illustrating spectral characteristics of a color filter proposed in FIG.
FIG. 81 is a diagram showing the spectral characteristics of the color filter proposed in FIGS. 2 (a), (b) and (c) of Japanese Patent Laid-Open No. 5-241143.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 101 ... Upper polarizing plate, 102 ... Counter substrate, 103 ... Liquid crystal, 104 ... Element substrate, 105 ... Lower polarizing plate, 106 ... Scattering reflector, 107 ... Color filter, 108 ... Counter electrode (scanning line), 109 ... Signal Line, 110... Pixel electrode, 111... MIM element.

Claims (3)

A reflective layer disposed on one of the pair of substrates, having a pair of substrates provided with electrodes on opposite inner surfaces and forming a matrix-like dot group, and a plurality of color filters having different colors. In a reflective color liquid crystal device having
Each of the plurality of color filters having different colors is provided only in a part of the region to be reflected and displayed by light modulation in each dot, and the area ratio of the color filter is 15% or more with respect to the region. Yes,
The reflective layer is a scattering reflective layer;
A reflective color liquid crystal device, wherein 80% or more of the light reflected by the scattering reflection layer is contained in a 30 ° cone. An electronic apparatus comprising the reflective color liquid crystal device according to claim 1 as a display unit. 3. The electronic apparatus according to claim 2, wherein the display unit of the reflective color liquid crystal device is attached so as to be movable with respect to the main body so that ambient light can be efficiently reflected by an observer. .

Images