JP3555894B2 - Manufacturing method of liquid crystal display device - Google Patents

Description

【０１０４】
液晶セル１６のセル厚（液晶層８の厚み）は５μｍとし、下記表１に示す５つの液晶表示装置（サンプル＃１１〜＃１５）を作製した。
【０１０５】
位相差板２、３としては、透明な支持体（例えばトリアセチルセルロース（ＴＡＣ）等）にディスコティック液晶を塗布し、ディスコティック液晶を傾斜配向させて架橋させて、第１のリターデーション値（ｎｃ−ｎａ）×ｄが０ｎｍ、第２のリターデーション値（ｎａ−ｎｂ）×ｄが１００ｎｍであり、図３に示した主屈折率ｎｂの方向がｘｙｚ座標軸におけるｚ軸方向から矢印Ａの方向に約２０゜傾き、主屈折率ｎｃの方向がｘ軸方向から矢印Ｂの方向に約２０゜傾いた屈折率楕円体の傾斜角度θ＝２０゜のものを作製した。
【０１０６】
さらに、比較のために、図１の液晶表示装置に示した液晶表示装置において、液晶層８の液晶材料として、
（（ｎｏ（４５０）−ｎｏ（５５０））／（ｎｏ（５５０）−ｎｏ（６５０））が１．５５及び２．５０のものを用いた以外は本実施形態と同様にして下記表１に示した２つの液晶表示装置（比較サンプル＃１００及び＃１０１）を作製した。
【０１０７】
上記サンプル＃１１〜＃１５及び比較サンプル＃１００、＃１０１について、白色光の下、目視試験を行った結果を下記表１に示す。尚、下記表１及び後述する実施形態２〜４の表２〜表４において、○は着色無し、△を使用に耐え得る程度の着色あり、×は使用に耐えない程度の着色ありを示す。
【０１０８】
【表１】

【０１０９】
上記表１に示すように、本実施形態のサンプル＃１２〜＃１４については、視角７０゜においてどの方向から見ても着色は確認されず、良好な画質が得られた。従って、
１．８５≦（（ｎｏ（４５０）−ｎｏ（５５０））／（ｎｏ（５５０）−ｎｏ（６５０））≦２．２０
の範囲では、特に優れた特性が得られることがわかる。
【０１１０】
また、本実施形態のサンプル＃１１及び＃１５については、視角５０゜まではどの方向から見ても着色は確認されず、良好な画質が得られた。視角６０゜では左右方向から見た場合に若干の着色が確認されたが、使用に耐え得る程度の着色であった。
【０１１１】
これに対して、比較サンプル＃１００及び＃１０１については、視角５０゜においてさえ左右方向から見た場合に使用に耐え得ない程の黄色から橙色の着色が確認された。
【０１１２】
さらに、位相差板２、３として透明な支持体にディスコティック液晶を塗布してハイブリッド配向させた以外は本実施形態のサンプル＃１１〜サンプル＃１５、及び比較サンプル＃１００、＃１０１と同様に作製した液晶表示装置についても同様の結果が得られた。
【０１１３】
（実施形態２）
本実施形態２では、図１に示した液晶表示装置において、液晶層８の液晶材料として、液晶材料の波長４５０ｎｍの光に対する異常光屈折率ｎｅ（４５０）、波長５５０ｎｍの光に対する異常光屈折率ｎｅ（５５０）及び波長６５０ｎｍの光に対する異常光屈折率ｎｅ（６５０）と、波長４５０ｎｍの光に対する正常光屈折率ｎｏ（４５０）、波長５５０ｎｍの光に対する正常光屈折率ｎｏ（５５０）及び波長６５０ｎｍの光に対する正常光屈折率ｎｏ（６５０）とを、
（（ｎｏ（４５０）−ｎｏ（５５０））／（ｎｏ（５５０）−ｎｏ（６５０）））／（（ｎｅ（４５０）−ｎｅ（５５０））／（ｎｅ（５５０）−ｎｅ（６５０））））≧１
とし、
かつ、液晶材料の波長４５０ｎｍの光に対する異常光屈折率ｎｅ（４５０）、波長５５０ｎｍの光に対する異常光屈折率ｎｅ（５５０）及び波長６５０ｎｍの光に対する異常光屈折率ｎｅ（６５０）の変化度合を、
１．７０≦（（ｎｅ（４５０）−ｎｅ（５５０））／（ｎｅ（５５０）−ｎｅ（６５０））≦２．３０
の範囲に設定したものを用いた。
【０１１４】
この液晶材料は、実施形態１において示した材料系をブレンドして調整した。
【０１１５】
液晶セル１６のセル厚は５μｍとし、下記表２に示す５つの液晶表示装置（サンプル＃２１〜＃２５）を作製した。
【０１１６】
位相差板２、３としては、透明な支持体（例えばトリアセチルセルロース（ＴＡＣ）等）にディスコティック液晶を塗布し、ディスコティック液晶を傾斜配向させて架橋させて、第１のリターデーション値（ｎｃ−ｎａ）×ｄが０ｎｍ、第２のリターデーション値（ｎａ−ｎｂ）×ｄが１００ｎｍであり、図３に示した主屈折率ｎｂの方向がｘｙｚ座標軸におけるｚ軸方向から矢印Ａの方向に約２０゜傾き、主屈折率ｎｃの方向がｘ軸方向から矢印Ｂの方向に約２０゜傾いた屈折率楕円体の傾斜角度θ＝２０゜のものを作製した。
【０１１７】
さらに、比較のために、図１の液晶表示装置に示した液晶表示装置において、液晶層８の液晶材料として、
（（ｎｅ（４５０）−ｎｅ（５５０））／（ｎｅ（５５０）−ｎｅ（６５０））が１．６０及び２．４０のものを用いた以外は本実施形態と同様にして下記表２に示した２つの液晶表示装置（比較サンプル＃２００及び＃２０１）を作製した。
【０１１８】
上記サンプル＃２１〜＃２５及び比較サンプル＃２００、＃２０１について、白色光の下、目視試験を行った結果を下記表２に示す。
【０１１９】
【表２】

【０１２０】
上記表２に示すように、本実施形態のサンプル＃２２〜＃２４については、視角７０゜においてどの方向から見ても着色は確認されず、良好な画質が得られた。従って、
１．８５≦（（ｎｅ（４５０）−ｎｅ（５５０））／（ｎｅ（５５０）−ｎｅ（６５０））≦２．１０
の範囲では、特に優れた特性が得られることがわかる。
【０１２１】
また、本実施形態のサンプル＃２１及び＃２５については、視角５０゜まではどの方向から見ても着色は確認されず、良好な画質が得られた。視角６０゜では左右方向から見た場合に若干の着色が確認されたが、使用に耐え得る程度の着色であった。
【０１２２】
これに対して、比較サンプル＃２００及び＃２０１については、視角５０゜においてさえ左右方向から見た場合に使用に耐え得ない程の黄色から橙色の着色が確認された。
【０１２３】
さらに、位相差板２、３として透明な支持体にディスコティック液晶を塗布してハイブリッド配向させた以外は本実施形態のサンプル＃２１〜サンプル＃２５、及び比較サンプル＃２００、＃２０１と同様に作製した液晶表示装置についても同様の結果が得られた。
【０１２４】
（実施形態３）
本実施形態３では、図１に示した液晶表示装置において、液晶層８の液晶材料として、液晶材料の波長４５０ｎｍの光に対する異常光屈折率ｎｅ（４５０）、波長５５０ｎｍの光に対する異常光屈折率ｎｅ（５５０）及び波長６５０ｎｍの光に対する異常光屈折率ｎｅ（６５０）と、波長４５０ｎｍの光に対する正常光屈折率ｎｏ（４５０）、波長５５０ｎｍの光に対する正常光屈折率ｎｏ（５５０）及び波長６５０ｎｍの光に対する正常光屈折率ｎｏ（６５０）とを、
（（ｎｏ（４５０）−ｎｏ（５５０））／（ｎｏ（５５０）−ｎｏ（６５０）））／（（ｎｅ（４５０）−ｎｅ（５５０））／（ｎｅ（５５０）−ｎｅ（６５０））））＜１
とし、
かつ、液晶材料の波長４５０ｎｍの光に対する正常光屈折率ｎｏ（４５０）、波長５５０ｎｍの光に対する正常光屈折率ｎｏ（５５０）及び波長６５０ｎｍの光に対する正常光屈折率ｎｏ（６５０）の変化度合を、
１．００≦（（ｎｏ（４５０）−ｎｏ（５５０））／（ｎｏ（５５０）−ｎｏ（６５０））≦１．６５
の範囲に設定したものを用いた。
【０１２５】
この液晶材料は、実施形態１において示した材料系をブレンドして調整した。
【０１２６】
液晶セル１６のセル厚は５μｍとし、下記表３に示す５つの液晶表示装置（サンプル＃３１〜＃３５）を作製した。
【０１２７】
位相差板２、３としては、透明な支持体（例えばトリアセチルセルロース（ＴＡＣ）等）にディスコティック液晶を塗布し、ディスコティック液晶を傾斜配向させて架橋させて、第１のリターデーション値（ｎｃ−ｎａ）×ｄが０ｎｍ、第２のリターデーション値（ｎａ−ｎｂ）×ｄが１００ｎｍであり、図３に示した主屈折率ｎｂの方向がｘｙｚ座標軸におけるｚ軸方向から矢印Ａの方向に約２０゜傾き、主屈折率ｎｃの方向がｘ軸方向から矢印Ｂの方向に約２０゜傾いた屈折率楕円体の傾斜角度θ＝２０゜のものを作製した。
【０１２８】
さらに、比較のために、図１の液晶表示装置に示した液晶表示装置において、液晶層８の液晶材料として
（（ｎｏ（４５０）−ｎｏ（５５０））／（ｎｏ（５５０）−ｎｏ（６５０））が０．９０及び１．７５のものを用いた以外は本実施形態と同様にして下記表３に示した２つの液晶表示装置（比較サンプル＃３００及び＃３０１）を作製した。
【０１２９】
上記サンプル＃３１〜＃３５及び比較サンプル＃３００、＃３０１について、白色光の下、目視試験を行った結果を下記表３に示す。
【０１３０】
【表３】

【０１３１】
上記表３に示すように、本実施形態のサンプル＃３２〜＃３４については、視角７０゜においてどの方向から見ても着色は確認されず、良好な画質が得られた。従って、
１．１５≦（（ｎｏ（４５０）−ｎｏ（５５０））／（ｎｏ（５５０）−ｎｏ（６５０））≦１．４５
の範囲では、特に優れた特性が得られることがわかる。
【０１３２】
また、本実施形態のサンプル＃３１、＃３５については、視角５０゜まではどの方向から見ても着色は確認されず、良好な画質が得られた。視角６０゜では左右方向から見た場合に若干の着色が確認されたが、使用に耐え得る程度の着色であった。
【０１３３】
これに対して、比較サンプル＃３００及び＃３０１については、視角５０゜においてさえ左右方向から見た場合に使用に耐え得ない程の黄色から橙色の着色が確認された。
【０１３４】
さらに、位相差板２、３として透明な支持体にディスコティック液晶を塗布してハイブリッド配向させた以外は本実施形態のサンプル＃３１〜サンプル＃３５、及び比較サンプル＃３００、＃３０１と同様に作製した液晶表示装置についても同様の結果が得られた。
【０１３５】
（実施形態４）
本実施形態４では、図１に示した液晶表示装置において、液晶層８の液晶材料として、液晶材料の波長４５０ｎｍの光に対する異常光屈折率ｎｅ（４５０）、波長５５０ｎｍの光に対する異常光屈折率ｎｅ（５５０）及び波長６５０ｎｍの光に対する異常光屈折率ｎｅ（６５０）と、波長４５０ｎｍの光に対する正常光屈折率ｎｏ（４５０）、波長５５０ｎｍの光に対する正常光屈折率ｎｏ（５５０）及び波長６５０ｎｍの光に対する正常光屈折率ｎｏ（６５０）とを、
（（ｎｏ（４５０）−ｎｏ（５５０））／（ｎｏ（５５０）−ｎｏ（６５０）））／（（ｎｅ（４５０）−ｎｅ（５５０））／（ｎｅ（５５０）−ｎｅ（６５０））））＜１
とし、
かつ、液晶材料の波長４５０ｎｍの光に対する異常光屈折率ｎｅ（４５０）、波長５５０ｎｍの光に対する異常光屈折率ｎｅ（５５０）及び波長６５０ｎｍの光に対する異常光屈折率ｎｅ（６５０）の変化度合を、
１．２０≦（（ｎｅ（４５０）−ｎｅ（５５０））／（ｎｅ（５５０）−ｎｅ（６５０））≦１．７０
の範囲に設定したものを用いた。
【０１３６】
この液晶材料は、実施形態１において示した材料系をブレンドして調整した。
【０１３７】
液晶セル１６のセル厚は５μｍとし、下記表４に示す５つの液晶表示装置（サンプル＃４１〜＃４５）を作製した。
【０１３８】
位相差板２、３としては、透明な支持体（例えばトリアセチルセルロース（ＴＡＣ）等）にディスコティック液晶を塗布し、ディスコティック液晶を傾斜配向させて架橋させて、第１のリターデーション値（ｎｃ−ｎａ）×ｄが０ｎｍ、第２のリターデーション値（ｎａ−ｎｂ）×ｄが１００ｎｍであり、図３に示した主屈折率ｎｂの方向がｘｙｚ座標軸におけるｚ軸方向から矢印Ａの方向に約２０゜傾き、主屈折率ｎｃの方向がｘ軸方向から矢印Ｂの方向に約２０゜傾いた屈折率楕円体の傾斜角度θ＝２０゜のものを作製した。
【０１３９】
さらに、比較のために、図１の液晶表示装置に示した液晶表示装置において、液晶層８の液晶材料として、
（（ｎｅ（４５０）−ｎｅ（５５０））／（ｎｅ（５５０）−ｎｅ（６５０））が１．１０及び１．８０のものを用いた以外は本実施形態と同様にして下記表２に示した２つの液晶表示装置（比較サンプル＃４００及び＃４０１）を作製した。
【０１４０】
上記サンプル＃４１〜＃４５及び比較サンプル＃４００、＃４０１について、白色光の下、目視試験を行った結果を下記表４に示す。
【０１４１】
【表４】

【０１４２】
上記表４に示すように、本実施形態のサンプル＃４２〜＃４４については、視角７０゜においてどの方向から見ても着色は確認されず、良好な画質が得られた。従って、
１．３５≦（（ｎｅ（４５０）−ｎｅ（５５０））／（ｎｅ（５５０）−ｎｅ（６５０））≦１．６０
の範囲では、特に優れた特性が得られることがわかる。
【０１４３】
また、本実施形態のサンプル＃４１及び＃４５については、視角５０゜まではどの方向から見ても着色は確認されず、良好な画質が得られた。視角６０゜では左右方向から見た場合に若干の着色が確認されたが、使用に耐え得る程度の着色であった。
【０１４４】
これに対して、比較サンプル＃４００及び＃４０１については、視角５０゜においてさえ左右方向から見た場合に使用に耐え得ない程の黄色から橙色の着色が確認された。
【０１４５】
さらに、位相差板２、３として透明な支持体にディスコティック液晶を塗布してハイブリッド配向させた以外は本実施形態のサンプル＃４１〜サンプル＃４５、及び比較サンプル＃４００、＃４０１と同様に作製した液晶表示装置についても同様の結果が得られた。
【０１４６】
（実施形態５）
本実施形態５では、図１に示した液晶表示装置において、液晶層８の液晶材料として波長５５０ｎｍの光に対する屈折率異方性Δｎ（５５０）を０．０７０、０．０８０、０．０９５に設定した材料を用い、液晶セル１６のセル厚を５μｍとして３つの液晶表示装置（サンプル＃５１〜＃５３）を作製した。各サンプルの正常光屈折率ｎｏの変化度合及び異常光屈折率ｎｅの変化度合を下記表５に示す。
【０１４７】
【表５】

【０１４８】
位相差板２、３としては、ディスコティック液晶を傾斜配向させた上記実施形態１と同様のものを用いた。
【０１４９】
さらに、比較のために、図１の液晶表示装置に示した液晶表示装置において、液晶層８の液晶材料として波長５５０ｎｍの光に対する屈折率異方性Δｎ（５５０）を０．０６０、０．１２０に設定したものを用いた以外は本実施形態と同様にして２つの液晶表示装置（比較サンプル＃５０１及び＃５０２）を作製した。
【０１５０】
上記サンプル＃５１〜＃５３及び比較サンプル＃５０１、＃５０２について、図５に示すような受光素子２１、増幅器２２及び記録装置２３を備えた測定系を用いて液晶表示装置の視角依存性を測定した。
【０１５１】
この測定系において、液晶表示装置の液晶セル１６は、ガラス基板９側の面１６ａが直交座標軸ｘｙｚの基準面ｘ−ｙの位置になるように設置される。
【０１５２】
受光素子２１は一定の立体受光角で受光し得る素子であり、液晶セル１６の面１６ａに垂直なｚ方向に対して角度φ（視角）をなす方向に、座標原点から所定距離を置いた位置に配置されている。
【０１５３】
測定時には、測定系に設置された液晶セル１６に対して面１６ａの反対側の面から波長５５０ｎｍの単色光を照射する。これにより、液晶セル１６を透過した単色光の一部が受光素子２１に入射される。そして、受光素子２１の出力は、増幅器２２で所定のレベルに増幅された後、波形メモリやレコーダ等を備えた記録装置２３によって記録される。
【０１５４】
この測定系に本実施形態のサンプル＃５１〜＃５３及び比較サンプル＃５０１、＃５０２を設置して、受光素子２１を一定の角度φで固定した場合の各液晶表示装置への印加電圧と受光素子２１の出力レベルとの関係を測定した。
【０１５５】
ここでは、ｘ方向が画面の下側であり、ｙ方向が画面の左側であると仮定して、角度φが５０゜となるように受光素子２１の配置位置を上方向、右方向及び左方向に各々変えて測定を行った。
【０１５６】
本実施形態のサンプル＃５１〜＃５３についての測定結果を図６（ａ）〜（ｃ）に、比較サンプル＃５０１及び＃５０２についての測定結果を図７（ａ）〜（ｃ）に示す。図６（ａ）〜（ｃ）及び図７（ａ）〜（ｃ）は、各液晶表示装置に印加される電圧に対する光の透過率（透過率−液晶印加電圧特性）を示すグラフであり、図６（ａ）及び図７（ａ）が図２の上方向から測定を行った結果であり、図６（ｂ）及び図７（ｂ）が図２の右方向から測定を行った結果であり、図６（ｃ）及び図７（ｃ）が図２の左方向から測定を行った結果である。
【０１５７】
この図６（ａ）〜（ｃ）において、一点鎖線で示した曲線Ｌ１、Ｌ４、Ｌ７が液晶層８にΔｎ（５５０）＝０．０７０の液晶材料を用いたサンプル＃５１を示し、実線で示した曲線Ｌ２、Ｌ５、Ｌ８は液晶層８にΔｎ（５５０）＝０．０８０の液晶材料を用いたサンプル＃５２を示し、点線で示した曲線Ｌ３、Ｌ６、Ｌ９は液晶層８にΔｎ（５５０）＝０．０９５の液晶材料を用いたサンプル＃５３を示す。図７（ａ）〜（ｃ）において、実線で示した曲線Ｌ１０、Ｌ１２、Ｌ１４は液晶層８にΔｎ（５５０）＝０．０６０の液晶材料を用いた比較サンプル＃５０１を示し、点線で示した曲線Ｌ１１、Ｌ１３、Ｌ１５は液晶層８にΔｎ（５５０）＝０．１２０の液晶材料を用いた比較サンプル＃５０２を示す。
【０１５８】
上方向の透過率−液晶印加電圧特性については、本実施形態のサンプル＃５１〜＃５３では図６（ａ）のＬ１〜Ｌ３に示すように、電圧が高くなるのに伴って透過率が充分下がることが確認された。これに対して、比較サンプル＃５０２では図７（ａ）のＬ１１に示すように、電圧を高くしても充分に透過率が下がらず、比較サンプル＃５０１では図７（ａ）のＬ１０に示すように、電圧が高くなるのに伴って透過率が一旦低下した後で再び上昇する反転現象が見られた。
【０１５９】
同様に、右方向の透過率−液晶印加電圧特性については、本実施形態のサンプル＃５１〜＃５３では図６（ｂ）のＬ４〜Ｌ６に示すように、電圧が高くなるのに伴って透過率がほぼ０近くまで低下することが確認された。一方、比較サンプル＃５０１では図７（ｂ）のＬ１２に示すように、電圧が高くなるのに伴って透過率がほぼ０近くまで低下するが、比較サンプル＃５０２では図７（ｂ）のＬ１３に示すように、電圧が高くなるに伴って透過率が一旦低下した後で再び上昇する反転現象が見られた。
【０１６０】
同様に、左方向の透過率−液晶印加電圧特性については、本実施形態のサンプル＃５１〜＃５３では図６（ｃ）のＬ７〜Ｌ９に示すように、電圧が高くなるのに伴って透過率がほぼ０近くまで低下することが確認された。一方、比較サンプル＃５０１では図７（ｃ）のＬ１４に示すように、電圧が高くなるのに伴って透過率がほぼ０近くまで低下するが、比較サンプル＃５０２では図７（ｃ）のＬ１５に示すように、電圧が高くなるに伴って透過率が一旦低下した後で再び上昇する反転現象が見られた。
【０１６１】
さらに、上記サンプル＃５１〜＃５３及び比較サンプル＃５０１、＃５０２について、白色光の下、目視試験を行ったところ、本実施形態のサンプル＃５１〜＃５３及び比較サンプル＃５０１については、視角５０゜まではどの方向から見ても着色は確認されず、良好な画質が得られた。
【０１６２】
これに対して、比較サンプル＃５０２については、視角５０゜において左右方向から見た場合に黄色から橙色の着色が確認された。
【０１６３】
以上の結果から、液晶層８の液晶材料として波長５５０ｎｍの光に対する屈折率異方性Δｎ（５５０）を０．０７０、０．０８０、０．０９５に設定した本実施形態の液晶表示装置（サンプル＃５１〜＃５３）では、図６（ａ）〜図６（ｃ）に示したように、電圧を印加していくと透過率が充分低下して反転現象も見られないため視野角が拡大しており、また、着色現象も見られないので液晶表示装置の表示品位が格段に向上していることがわかる。
【０１６４】
これに対して、液晶層８の液晶材料として波長５５０ｎｍの光に対する屈折率異方性Δｎ（５５０）を０．０６０、０．１２０に設定した液晶表示装置（比較サンプル＃５０１及び＃５０２）では、図７（ａ）〜図７（ｃ）に示したように、視角依存性が充分改善されていないことがわかる。
【０１６５】
さらに、位相差板２、３として透明な支持体にディスコティック液晶を塗布してハイブリッド配向させた以外は本実施形態のサンプル＃５１〜サンプル＃５３、及び比較サンプル＃５０１、＃５０２と同様に作製した液晶表示装置についても同様の結果が得られた。
【０１６６】
上記位相差板２、３の屈折率楕円体の傾斜角度θを変化させて、透過率−液晶印加電圧特性の傾斜角度θに対する依存性を調べた結果、１５゜≦θ≦７５゜の範囲であれば、位相差板２、３におけるディスコティック液晶の配向状態に関係なく、基本的に上述したものと同様な結果が得られた。これに対して、傾斜角度が１５゜未満又は７５゜を超える場合には、反視角方向における視野角が拡大されないことが確認された。
【０１６７】
上記位相差板２、３の第２のリターデーション値（ｎａ−ｎｂ）×ｄを変化させて、透過率−液晶印加電圧特性の第２のリターデーション値に対する依存性を調べた結果、第２のリターデーション値が８０ｎｍ以上２５０ｎｍ以下の範囲であれば、位相差板２、３におけるディスコティック液晶の配向状態に関係なく、基本的に上述したものと同様な結果が得られた。これに対して、第２のリターデーション値が８０ｎｍ未満又は２５０ｎｍを超える場合には、横方向（左右方向）における視野角が拡大されないことが確認された。
【０１６８】
さらに、上記比較サンプル＃５０１及び＃５０２の目視試験の結果を基にして、図１の液晶表示装置に示した液晶表示装置において、液晶層８の液晶材料として波長５５０ｎｍの光に対する屈折率異方性Δｎ（５５０）を０．０６５、０．１００、０．１１５に設定したものを用いた以外は本実施形態と同様にして３つの液晶表示装置（サンプル＃５４〜＃５６）を作製した。
【０１６９】
図５に示した測定系にこれらのサンプル＃５４〜＃５６を設置して、受光素子２１を一定の角度φで固定した場合の各液晶表示装置への印加電圧と受光素子２１の出力レベルとの関係を測定し、さらに、白色光の下、目視試験を行った。
【０１７０】
その結果、波長５５０ｎｍの光に対する屈折率異方性Δｎ（５５０）を０．１００、０．１１５に設定した本実施形態のサンプル＃５５及び＃５６では、角度φ＝５０゜とした場合に左右方向において電圧を高くするとわずかに透過率の上昇が確認された。しかしながら、目視においては反転現象が生じておらず、この程度の透過率の上昇は使用に耐え得るものであった。上方向においては、何等問題のない結果が得られた。一方、波長５５０ｎｍの光に対する屈折率異方性Δｎ（５５０）を０．０６５に設定した本実施形態のサンプル＃５４では、上述した比較サンプル＃５０１と同様に、上方向において電圧を高くするに伴って透過率が一旦低下した後で再び上昇するような反転現象があったが、図７（ａ）に示した比較サンプル＃５０１（Ｌ１０）に比べて透過率の上昇度合は小さく、使用に耐え得るものであった。左右方向においては、何等問題のない結果が得られた。
【０１７１】
また、目視試験においては、本実施形態のサンプル＃５５及び＃５６について黄色から橙色の若干の着色が確認されたが、問題にならない程度の着色であった。一方、本実施形態のサンプル＃５４については若干の青みを呈していることが確認されたが、問題にならない程度の青みであった。
【０１７２】
さらに、サンプル＃５４と比較サンプル＃５０１について、１Ｖ程度の電圧を印加して液晶セル１６の表面の法線方向における白表示時の透過率を測定した。その結果、比較サンプル＃５０１では使用に耐え得ない程度の透過率の低下が見られた。これに対して、本実施形態のサンプル＃５４では若干の透過率の低下が確認されたが、使用に耐え得る程度のものであった。
【０１７３】
【発明の効果】
以上詳述したように本発明による場合には、屈折率楕円体の３つの主屈折率ｎａ、ｎｂ及びｎｃがｎａ＝ｎｃ＞ｎｂの関係を有し、表面に概ね平行な主屈折率ｎａ及びｎｃのうちの一方の方向を軸として、主屈折率ｎｂの方向が表面の法線方向から時計回り又は反時計回りに傾斜すると共に、主屈折率ｎａ及びｎｃの他方の方向が表面に概ね平行な方向から時計回り又は反時計回りに傾斜している位相差板を用いることにより、液晶表示素子の位相差変化を補償することができる。それに加えて、液晶層の液晶材料の正常光屈折率ｎｏの波長に対する変化度合及び異常光屈折率ｎｅの波長に対する変化度合のうちの少なくとも一方を視角に依存した画面着色が発生しない範囲に設定することにより、視角に依存した液晶表示画面の着色をより一層防止することが可能となり、さらに、反転現象や反視角方向のコントラスト比の低下についても、位相差板の補償機能のみの場合よりもさらに改善することができる。
【０１７４】
さらに、本発明では、液晶材料の屈折率の波長に対する変化度合について、視角に依存した画面着色が発生しない範囲が異なる材料があることを考慮して、各々の場合に応じた範囲に設定することにより視角に依存した液晶表示画面の着色をより一層防止することが可能となり、さらに、反転現象や反視角方向のコントラスト比の低下についても、位相差板の補償機能のみの場合よりもさらに改善することができる。
【０１７５】
特に、本発明では、通常の液晶表示装置に対して要求される視角５０゜を越える視角６０゜において、あらゆる方向から見て充分使用に耐え得る程度まで液晶表示画面の着色を抑えることが可能となる。
【０１７６】
さらに、本発明では、視角７０゜というさらに広視野角の液晶表示装置において、どの方向から見ても液晶表示画面に全く着色現象が無い状態を実現することができる。
【０１７７】
本発明では、波長５５０ｎｍの光に対する屈折率異方性Δｎ（５５０）を０．０６０より大きく０．１２０より小さい範囲に設定することにより、液晶表示素子に視角に応じて生じる位相差を解消することができる。よって、液晶表示画面において視角に依存して生じる着色現象は当然ながら、コントラスト変化や左右方向の反転現象等もさらに改善することができる。
【０１７８】
さらに、本発明では、波長５５０ｎｍの光に対する屈折率異方性Δｎ（５５０）を０．０７０以上０．０９５以下の範囲に設定することにより、より一層、視角に応じて生じる位相差を効果的に解消することができる。よって、液晶表示画面において視角に依存して生じる着色現象、コントラスト変化や左右方向の反転現象等をさらに確実に改善することができる。
【０１７９】
本発明では、屈折率楕円体の傾斜角を１５゜以上７５゜以下の範囲に設定することにより、位相差素子による位相差の補償機能を確実に得ることができるので、視認性を確実に向上することができる。
【０１８０】
本発明では、位相差素子の主屈折率ｎａ及びｎｂの差と、位相差素子の厚さｄとの積（ｎａ−ｎｂ）×ｄを８０ｎｍ以上２５０ｎｍ以下の範囲に設定することにより、位相差素子による位相差の補償機能を確実に得ることができるので、視認性を確実に向上することができる。
【図面の簡単な説明】
【図１】本発明の一実施形態である液晶表示装置の構成を示す断面図である。
【図２】図１の液晶表示装置における配向膜のラビング方向と視角方向との関係を示す図である。
【図３】図１の液晶表示装置における位相差板の主屈折率の方向を示す斜視図である。
【図４】図１の液晶表示装置における液晶表示素子、偏光板及び位相差板の光学的な配置を示す斜視図である。
【図５】実施形態５の液晶表示装置の視角依存性を測定するための測定系を示す斜視図である。
【図６】実施形態５の液晶表示装置の透過率−液晶印加電圧特性を示すグラフである。
【図７】比較例の液晶表示装置の透過率−液晶印加電圧特性を示すグラフである。
【図８】ＴＮ液晶表示素子における液晶分子の捩れ配向を示す模式図である。
【符号の説明】
１ 液晶表示素子
２、３ 位相差板
４、５ 偏光板
６、７ 電極基板
８ 液晶層
９、１２ 透光性基板
１０、１３ 透明電極
１１、１４ 配向膜
１５ シール樹脂
１６ 液晶セル
１７ 駆動回路[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal display device in which a viewing angle of a display screen is improved by combining a liquid crystal display element and a retardation element having optical anisotropy.
[0002]
[Prior art]
Conventionally, liquid crystal display devices using nematic liquid crystal have been widely used for numerical segment type display devices such as watches and calculators, but recently, they have been used for word processors, notebook personal computers, and liquid crystal televisions for vehicles. It has become.
[0003]
This liquid crystal display device generally has a pair of light-transmitting substrates which are arranged to face each other with a liquid crystal layer interposed therebetween, and electrode wirings for turning on / off pixels are formed on the substrate. I have. For example, in an active matrix type liquid crystal display device, pixel electrodes for applying a voltage to a liquid crystal are provided in a matrix, and an active element such as a field effect transistor is used as switching means for selectively applying a potential to each pixel electrode. Are provided on the substrate together with the electrode wirings. Further, in a liquid crystal display device that performs color display, a color filter layer of red, green, blue, or the like is provided on a substrate.
[0004]
In such a liquid crystal display device, a different display method is appropriately selected and used depending on the twist angle of the liquid crystal. Among them, for example, an active drive type twisted nematic liquid crystal display method (hereinafter, referred to as a TN method) and a multiplex drive type super twisted nematic liquid crystal display method (hereinafter, referred to as an STN method) are well known.
[0005]
In the former TN mode, display is performed by aligning nematic liquid crystal molecules in a 90 ° twisted state between a pair of substrates and guiding light along the twisted direction. The latter STN system utilizes the fact that the light transmittance near the threshold of the voltage applied to the liquid crystal changes sharply by making the twist angle of the nematic liquid crystal molecules larger than 90 ° between a pair of substrates.
[0006]
Among these display methods, the STN method utilizes the birefringence effect of liquid crystal, and thus causes a coloration unique to the background of the display screen due to color interference. Conventionally, it has been considered effective to use an optical compensator in order to prevent such coloring and perform black-and-white display by the STN method. The display method using the optical compensator is roughly classified into a double super twist nematic phase compensation method (hereinafter, referred to as DSTN method) and a film type phase compensation method (hereinafter, referred to as film addition type method).
[0007]
The DSTN method is a structure having a two-layer liquid crystal cell including a display liquid crystal cell and a liquid crystal cell that is twisted at a twist angle in a direction opposite to the display liquid crystal cell. , In which a film having optical anisotropy is arranged. From the viewpoint of lightness and low cost, the film addition type system is considered to be effective.
[0008]
In the STN system, since the black-and-white display characteristics are improved by adopting these phase compensation systems, a color STN liquid crystal display device in which a color filter layer is provided to enable color display is realized.
[0009]
On the other hand, the TN method is roughly classified into a normally black method and a normally white method.
[0010]
In the former normally black mode, a pair of polarizing plates are arranged so that the polarization directions thereof are parallel to each other with both sides of the liquid crystal display element interposed therebetween, and the liquid crystal layer is black when no on-voltage is applied (off state). Is displayed. In the latter normally white mode, a pair of polarizing plates are arranged so that the polarization directions thereof are orthogonal to each other with both sides of the liquid crystal display element interposed therebetween, and white is displayed in an off state on the liquid crystal layer. Among these, the normally white method is effective from the viewpoints of display contrast, color reproducibility, display angle dependency, and the like.
[0011]
By the way, in the above-mentioned TN type liquid crystal display device, since the liquid crystal molecules have the refractive index anisotropy Δn and the liquid crystal molecules are inclined and oriented with respect to the upper and lower substrates, the observer may be disturbed. There is a problem that the contrast of the displayed image changes depending on the viewing direction and viewing angle of the display screen, and the viewing angle dependency increases. This problem will be described below.
[0012]
FIG. 8 schematically shows a cross-sectional structure of a liquid crystal display element 31 of the TN mode, and shows a state in which a halftone display voltage is applied to the liquid crystal layer and the liquid crystal molecules 32 rise slightly.
[0013]
In the liquid crystal display element 31, the linearly polarized light 35 passing in the normal direction of the surface of the pair of substrates 33 and 34 and the linearly polarized light 36 and 37 passing with an inclination to the normal direction intersect with the liquid crystal molecules 32. Each angle is different. Here, since the liquid crystal molecules 32 have a refractive index anisotropy Δn, normal light and extraordinary light are generated when each of the linearly polarized light 35, 36, and 37 passes through the liquid crystal molecules 32, and the phase difference is caused by these phase differences. This is converted into elliptically polarized light, which causes viewing angle dependence.
[0014]
Further, in the actual liquid crystal layer, the tilt angle of the liquid crystal molecules 32 is different between the vicinity of the intermediate portion between the substrates 33 and 34 and the vicinity of the substrates 33 and 34, and the axis is set with the normal direction of the substrate surface as the axis. Since the liquid crystal molecules 32 are twisted by 90 °, they also cause viewing angle dependence.
[0015]
As described above, the linearly polarized lights 35, 36, and 37 passing through the liquid crystal layer are subjected to various birefringence effects depending on their directions and angles, and exhibit complicated viewing angle dependence.
[0016]
For example, when the viewing angle is inclined from the normal direction of the screen to the normal viewing angle direction (downward direction of the screen), a phenomenon that the display screen is colored at a certain angle or more (hereinafter, referred to as a coloring phenomenon) and a phenomenon that the black and white are reversed (hereinafter, referred to as a coloring phenomenon). , An inversion phenomenon) occurs. Further, when the viewing angle is inclined from the normal direction of the screen to the anti-viewing angle direction (upward direction of the screen), the contrast sharply decreases.
[0017]
Further, in the above-described liquid crystal display device, there is a problem that the viewing angle becomes narrower as the display screen becomes larger. For example, when a large liquid crystal display screen is viewed from the front at a short distance, colors displayed at the top and bottom of the screen may be different due to viewing angle dependence. This is because the larger the display screen, the greater the viewing angle of the entire screen, which is the same as viewing the display screen from an oblique direction.
[0018]
In order to improve the viewing angle dependency in such a TN mode, a retardation plate (or retardation film) as an optical element having optical anisotropy (retardation element) is provided between the liquid crystal display element and the polarizing plate. Has been proposed.
[0019]
In this method, light that has passed through liquid crystal molecules having refractive index anisotropy and has been converted from linearly polarized light to elliptically polarized light passes through a retardation plate provided on one or both sides of a liquid crystal layer having refractive index anisotropy. Let it. This makes it possible to compensate for a change in the phase difference between the normal light and the extraordinary light generated according to the viewing angle and to reconvert the light into linearly polarized light, thereby improving the viewing angle dependency.
[0020]
For example, Japanese Patent Application Laid-Open No. Hei 5-313159 proposes a method of using a retardation plate in which one main refractive index direction of an index ellipsoid is parallel to a normal direction of the surface of the retardation plate. . However, there is a limit to improving the reversal phenomenon in the normal viewing direction even if this retardation plate is used.
[0021]
Japanese Patent Application Laid-Open No. 6-75116 proposes a method of using a retardation plate in which the main refractive index direction of an index ellipsoid is inclined with respect to the normal direction of the surface of the retardation plate. . Here, the following two types of retardation plates are mentioned.
[0022]
One is to make the direction of the minimum principal refractive index of the three main refractive indices of the refractive index ellipsoid of the retardation plate parallel to the surface of the retardation plate, and One direction is inclined at an angle of θ with respect to the surface of the phase difference plate, and the other direction is inclined at an angle of θ with respect to the normal direction of the surface of the phase difference plate, so that the value of θ is 20 ° ≦ θ ≦ 70 °.
[0023]
The other is that the three main refractive indices na, nb, and nc of the refractive index ellipsoid of the phase difference plate are na = nc> nb, and the direction of the main refractive index na or nc parallel to the surface of the phase difference plate is changed. As an axis, the direction of the main refractive index nb is tilted clockwise or counterclockwise from the normal direction of the surface, and the direction of the main refractive index nc or na is tilted clockwise or counterclockwise from the direction parallel to the surface. This is a retardation plate in which the refractive index ellipsoid is inclined.
[0024]
Of these two types of retardation plates, the former can be a uniaxial one and a biaxial one, respectively. In the latter case, only one such retardation plate may be used, but two retardation plates are used in combination such that the inclination directions of the main refractive indices nb form an angle of 90 ° with each other. You can also.
[0025]
By arranging at least one such retardation plate between the liquid crystal display element and the polarizing plate, the change in contrast, coloring phenomenon, and inversion phenomenon depending on the viewing angle of the displayed image are improved to some extent. be able to.
[0026]
Further, Japanese Patent Application Laid-Open No. 8-101381 discloses that, in a liquid crystal display device using the latter two types of retardation plates, the wavelength dispersion of the refractive index anisotropy of the retardation plate is changed by the refractive index anisotropy of the liquid crystal. There has been proposed a method for improving the viewing angle characteristics of a display color by making the wavelength dispersion smaller than the wavelength dispersion. Also, Japanese Patent Application Laid-Open No. Hei 5-215912 discloses that in a liquid crystal display device using a conventional retardation plate in which a refractive index ellipsoid is not tilted, the wavelength dispersion of the refractive index anisotropy of the retardation plate is changed by the refractive index difference of the liquid crystal. There has been proposed a method of improving the viewing angle characteristics by making the wavelength dispersion smaller than the isotropic wavelength dispersion.
[0027]
Here, as a method of adjusting the wavelength dispersion of the phase difference plate, a method of changing the material of the phase difference plate and a method of adjusting the thickness of the phase difference plate are exemplified.
[0028]
[Problems to be solved by the invention]
In a situation where a liquid crystal display device having a wide viewing angle and a high display quality is desired as in today, further improvement of the viewing angle dependency is required, and it is disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 6-75116. It is not always sufficient to use a phase plate.
[0029]
On the other hand, in the methods disclosed in JP-A-8-101381 and JP-A-5-215912, there are limitations on the materials that can be used as a retardation plate. Boards are not realistic. On the other hand, if the thickness of the retardation plate is increased, the phase difference changes due to the change in the optical path length and the change in the refractive index ellipsoid when the viewing angle is degraded. Furthermore, this method has not yet been able to improve the coloring phenomenon of the display screen when the viewing angle is reduced, and there is still room for improvement.
[0030]
The present invention has been made in order to solve such problems of the related art, and further improves a contrast change, a coloring phenomenon, a reversal phenomenon, and the like that occur depending on a viewing angle, and in particular, a liquid crystal screen depending on a viewing angle. It is an object of the present invention to provide a liquid crystal display device capable of effectively improving a coloring phenomenon.
[0031]
[Means for Solving the Problems]
Liquid crystal display device of the present inventionManufacturing methodAre a liquid crystal display element in which a liquid crystal layer is sandwiched between a pair of substrates each having an electrode layer and an alignment film, a pair of polarizers sandwiching both sides of the liquid crystal display element, at least one polarizer and the liquid crystal. At least one phase difference element provided between the display elements.AndThe three main refractive indices na, nb, and nc of the refractive index ellipsoid of the phase difference element have a relationship of na = nc> nb, and among the main refractive indexes na and nc substantially parallel to the surface of the phase difference element. With one direction as an axis, the direction of the main refractive index nb is inclined clockwise or counterclockwise from the normal direction of the surface, and the other direction of the main refractive indices na and nc is from a direction substantially parallel to the surface. Tilted clockwise or counterclockwiseA method of manufacturing a liquid crystal display device,
The extraordinary light refractive index ne (450) for the light of wavelength 450 nm, the extraordinary refractive index ne (550) for the light of wavelength 550 nm, and the extraordinary refractive index ne (650) for the light of wavelength 650 nm of the liquid crystal material in the liquid crystal layer The normal light refractive index no (450) for light having a wavelength of 450 nm, the normal light refractive index no (550) for light having a wavelength of 550 nm, and the normal light refractive index no (650) for light having a wavelength of 650 nm are as follows:
((No (450) -no (550)) / (no (550) -no (650))) / ((ne (450) -ne (550)) / (ne (550) -ne (650)) ) ≧ 1
And,
1.65 ≦ (no (450) −no (550)) / (no (550) −no (650)) ≦ 2.40
And the step of blending and adjusting the liquid crystal material within the range described above, whereby the above object is achieved.
The method for manufacturing a liquid crystal display device according to the present invention includes a liquid crystal display element in which a liquid crystal layer is sandwiched between a pair of substrates each having an electrode layer and an alignment film, and a pair of polarizers sandwiching both sides of the liquid crystal display element. , At least one polarizer and at least one retardation element provided between the liquid crystal display elements, and the three main refractive indices na, nb, and nc of the refractive index ellipsoid of the retardation element are provided. has a relationship of na = nc> nb, and the direction of the main refractive index nb is from the direction normal to the surface, with one of the main refractive indices na and nc substantially parallel to the surface of the phase difference element as the axis. A method for manufacturing a liquid crystal display device which is inclined clockwise or counterclockwise, and wherein the other direction of the main refractive indices na and nc is inclined clockwise or counterclockwise from a direction substantially parallel to the surface, 450 nm wavelength light of the liquid crystal material in the liquid crystal layer The extraordinary light refractive index ne (450), the extraordinary light refractive index ne (550) for light having a wavelength of 550 nm, the extraordinary light refractive index ne (650) for light having a wavelength of 650 nm, and the normal light refractive index no ( 450), a normal light refractive index no (550) for light having a wavelength of 550 nm, and a normal light refractive index no (650) for light having a wavelength of 650 nm.
((No (450) -no (550)) / (no (550) -no (650))) / ((ne (450) -ne (550)) / (ne (550) -ne (650)) ) ≧ 1
And,
The degree of change of the extraordinary light refractive index ne (450) for the light of wavelength 550 nm, the extraordinary light refractive index ne (550) for the light of wavelength 550 nm, and the extraordinary light refractive index ne (650) for the light of wavelength 650 nm of the liquid crystal material is as follows:
1.70 ≦ (ne (450) −ne (550)) / (ne (550) −ne (650)) ≦ 2.30
And the step of blending and adjusting the liquid crystal material within the range described above, whereby the above object is achieved.
The method for manufacturing a liquid crystal display device according to the present invention includes a liquid crystal display element in which a liquid crystal layer is sandwiched between a pair of substrates each having an electrode layer and an alignment film, and a pair of polarizers sandwiching both sides of the liquid crystal display element. , At least one polarizer and at least one retardation element provided between the liquid crystal display elements, and the three main refractive indices na, nb, and nc of the refractive index ellipsoid of the retardation element are provided. na = nc> nb, and of the main refractive indices na and nc substantially parallel to the surface of the phase difference element. With one direction as an axis, the direction of the main refractive index nb is inclined clockwise or counterclockwise from the normal direction of the surface, and the other direction of the main refractive indices na and nc is from a direction substantially parallel to the surface. A method for manufacturing a liquid crystal display device which is tilted clockwise or counterclockwise, comprising: an extraordinary light refractive index ne (450) of a liquid crystal material in the liquid crystal layer with respect to light having a wavelength of 450 nm; The refractive index ne (550) and the extraordinary light refractive index ne (650) for light having a wavelength of 650 nm, the normal light refractive index no (450) for light having a wavelength of 450 nm, the normal light refractive index no (550) for light having a wavelength of 550 nm, and The normal light refractive index no (650) for light having a wavelength of 650 nm is:
((No (450) -no (550)) / (no (550) -no (650))) / ((ne (450) -ne (550)) / (ne (550) -ne (650)) ) <1
And,
1.00 ≦ (no (450) −no (550)) / (no (550) −no (650)) ≦ 1.65
And the step of blending and adjusting the liquid crystal material within the range described above, whereby the above object is achieved.
The method for manufacturing a liquid crystal display device according to the present invention includes a liquid crystal display element in which a liquid crystal layer is sandwiched between a pair of substrates each having an electrode layer and an alignment film, and a pair of polarizers sandwiching both sides of the liquid crystal display element. , At least one polarizer and at least one retardation element provided between the liquid crystal display elements, and the three main refractive indices na, nb, and nc of the refractive index ellipsoid of the retardation element are provided. has a relationship of na = nc> nb, and the direction of the main refractive index nb is from the direction normal to the surface, with one of the main refractive indices na and nc substantially parallel to the surface of the phase difference element as the axis. A method for manufacturing a liquid crystal display device which is inclined clockwise or counterclockwise, and wherein the other direction of the main refractive indices na and nc is inclined clockwise or counterclockwise from a direction substantially parallel to the surface, 450 nm wavelength light of the liquid crystal material in the liquid crystal layer The extraordinary light refractive index ne (450), the extraordinary light refractive index ne (550) for light having a wavelength of 550 nm, the extraordinary light refractive index ne (650) for light having a wavelength of 650 nm, and the normal light refractive index no ( 450), a normal light refractive index no (550) for light having a wavelength of 550 nm, and a normal light refractive index no (650) for light having a wavelength of 650 nm.
((No (450) -no (550)) / (no (550) -no (650))) / ((ne (450) -ne (550)) / (ne (550) -ne (650)) ) <1
And,
A step of blending and adjusting the liquid crystal material in a range of 1.20 ≦ (ne (450) −ne (550)) / (ne (550) −ne (650)) ≦ 1.70. Thereby, the above object is achieved.
[0046]
Hereinafter, the process of completing the present invention and the operation of the present invention will be described.
[0047]
In the present invention, the three main refractive indices na, nb, and nc of the refractive index ellipsoid of the phase difference element have a relationship of na = nc> nb, and the main refractive index substantially parallel to the surface of the phase difference element. With one of the directions of na and nc as an axis, the direction of the main refractive index nb is inclined clockwise or counterclockwise from the normal direction of the surface, and the other direction of the main refractive indexes na and nc is on the surface. By being inclined clockwise or counterclockwise from a substantially parallel direction, the refractive index ellipsoid of the phase difference element is inclined. When the linearly polarized light passes through the liquid crystal layer having birefringence to generate normal light and extraordinary light, the transmitted light is changed to elliptically polarized light according to the phase difference. The phase difference from the extraordinary light is compensated.
[0048]
However, such a compensating function of the retardation plate alone cannot sufficiently satisfy the demand for further improving the viewing angle dependency.
[0049]
Therefore, as a result of repeated studies by the present inventors, it has been found that the wavelength dependence of the normal refractive index no of the liquid crystal material and the wavelength dependence of the extraordinary refractive index ne of the liquid crystal material in the liquid crystal layer encapsulated in the liquid crystal display element. When the matching with the wavelength dependence of the refractive index of the retardation plate is poor, it is found that when the viewing angle is lowered or halftone display is performed, coloring becomes remarkable and the state of the displayed image is significantly deteriorated. The inventors have found that the degree of change of the normal refractive index no of the material with respect to the wavelength and the degree of change of the extraordinary refractive index ne of the liquid crystal material with respect to the wavelength affect the coloring of the liquid crystal display screen, thereby completing the present invention. Was.
[0050]
In the liquid crystal display device of the present invention, at least one of the degree of change in the normal refractive index no of the liquid crystal material with respect to the wavelength and the extraordinary refractive index ne is set to a range in which the screen coloring depending on the viewing angle does not occur. ing. This makes it possible to further prevent the coloring of the screen, and further, as shown in an embodiment described later, the contrast change and inversion phenomenon can be further improved as compared with the case where only the compensation function of the retardation plate is used. did it.
[0051]
Furthermore, as a result of repeated studies by the inventors of the present application, in the liquid crystal layer encapsulated in the liquid crystal display element, the degree of change in the refractive index of the liquid crystal material with respect to the wavelength, the range in which the viewing angle-dependent screen coloring does not occur is different. Turned out to be present.
[0052]
Therefore, in the liquid crystal display device of the present invention, the extraordinary light refractive index ne (450) for the liquid crystal material having a wavelength of 450 nm, the extraordinary light refractive index ne (550) for the light having a wavelength of 550 nm, and the abnormal light refractive index ne (550) for the light having a wavelength of 650 nm. The light refractive index ne (650), the normal light refractive index no (450) for light having a wavelength of 450 nm, the normal light refractive index no (550) for light having a wavelength of 550 nm, and the normal light refractive index no (650) for light having a wavelength of 650 nm And
((No (450) -no (550)) / (no (550) -no (650))) / ((ne (450) -ne (550)) / (ne (550) -ne (650)) )) ≧ 1
Has the relationship of
((No (450) -no (550)) / (no (550) -no (650))) / ((ne (450) -ne (550)) / (ne (550) -ne (650)) )) <1
In each case, at least one of the degree of change to the wavelength of the normal light refractive index no of the liquid crystal material and the degree of change to the wavelength of the extraordinary light refractive index ne of the liquid crystal material is changed to the viewing angle. The range was set so that dependent screen coloring did not occur.
[0053]
The degree of change of the normal refractive index no of the liquid crystal material with respect to the wavelength and the degree of change of the extraordinary refractive index ne of the liquid crystal material with respect to the wavelength are specifically set in the following ranges.
[0054]
(1) The extraordinary refractive index ne (450) of the liquid crystal material with respect to light having a wavelength of 450 nm, the extraordinary refractive index ne (550) with respect to light having a wavelength of 550 nm, and the extraordinary refractive index ne (650) with respect to light having a wavelength of 650 nm. A normal light refractive index no (450) for light of 450 nm, a normal light refractive index no (550) for light of 550 nm, and a normal light refractive index no (650) for light of 650 nm,
((No (450) -no (550)) / (no (550) -no (650))) / ((ne (450) -ne (550)) / (ne (550) -ne (650)) )) ≧ 1
If you have the relationship
The degree of change of the normal light refractive index no (450) with respect to light having a wavelength of 450 nm, the normal light refractive index no (550) with respect to light having a wavelength of 550 nm, and the normal light refractive index no (650) with respect to light having a wavelength of 650 nm of the liquid crystal material is as follows.
1.65 ≦ ((no (450) −no (550)) / (no (550) −no (650)) ≦ 2.40
Set to the range.
[0055]
Alternatively, the degree of change of the extraordinary light refractive index ne (450) with respect to light having a wavelength of 450 nm, the extraordinary light refractive index ne (550) with respect to light having a wavelength of 550 nm, and the extraordinary light refractive index ne (650) with respect to light having a wavelength of 650 nm is determined. ,
1.70 ≦ ((ne (450) −ne (550)) / (ne (550) −ne (650)) ≦ 2.30
Set to the range.
[0056]
At least one of these ranges causes slight coloring at a viewing angle of 50 ° required for a normal liquid crystal display device, as shown in Embodiments 1 and 2 described below. A display which can be sufficiently used even when viewed from the direction can be obtained.
[0057]
More preferably,
1.85 ≦ ((no (450) −no (550)) / (no (550) −no (650)) ≦ 2.20
Set to the range.
[0058]
Or
1.85 ≦ ((ne (450) −ne (550)) / (ne (550) −ne (650)) ≦ 2.10.
Set to the range.
[0059]
By setting at least one of these ranges, as described in Embodiments 1 and 2 described later, in a liquid crystal display device having a wider viewing angle of 70 °, no coloring phenomenon is seen from any direction. No display is obtained.
[0060]
(2) The extraordinary light refractive index ne (450) for the light of wavelength 450 nm, the extraordinary light refractive index ne (550) for the light of wavelength 550 nm, the extraordinary light refractive index ne (650) for the light of wavelength 650 nm, and the wavelength of the liquid crystal material. A normal light refractive index no (450) for light of 450 nm, a normal light refractive index no (550) for light of 550 nm, and a normal light refractive index no (650) for light of 650 nm,
((No (450) -no (550)) / (no (550) -no (650))) / ((ne (450) -ne (550)) / (ne (550) -ne (650)) )) <1
If you have the relationship
The degree of change of the normal light refractive index no (450) with respect to light having a wavelength of 450 nm, the normal light refractive index no (550) with respect to light having a wavelength of 550 nm, and the normal light refractive index no (650) with respect to light having a wavelength of 650 nm of the liquid crystal material is as follows.
1.00 ≦ ((no (450) −no (550)) / (no (550) −no (650)) ≦ 1.65
Set to the range.
[0061]
Alternatively, the degree of change of the extraordinary light refractive index ne (450) with respect to light having a wavelength of 450 nm, the extraordinary light refractive index ne (550) with respect to light having a wavelength of 550 nm, and the extraordinary light refractive index ne (650) with respect to light having a wavelength of 650 nm is determined. ,
1.20 ≦ ((ne (450) −ne (550)) / (ne (550) −ne (650)) ≦ 1.70
Set to the range.
[0062]
At least one of these ranges causes slight coloring at a viewing angle of 50 ° required for a normal liquid crystal display device, as described in Embodiments 3 and 4 described later. A display which can be sufficiently used even when viewed from the direction can be obtained.
[0063]
More preferably,
1.15 ≦ ((no (450) −no (550))) / (no (550) −no (650)) ≦ 1.45
Set to the range.
[0064]
Or
1.35 ≦ ((ne (450) −ne (550)) / (ne (550) −ne (650)) ≦ 1.60
Set to the range.
[0065]
By setting at least one of these ranges, as shown in Embodiments 3 and 4 described later, in a liquid crystal display device having a wider viewing angle of 70 °, no coloring phenomenon is seen from any direction. No display is obtained.
[0066]
In the liquid crystal display device of the present invention, it is preferable that the refractive index anisotropy Δn (550) of the liquid crystal material with respect to light having a wavelength of 550 nm is set in a range larger than 0.060 and smaller than 0.120. When the refractive index anisotropy Δn (550) of the liquid crystal material with respect to light having a wavelength of 550 nm, which is a visible light region, is 0.060 or less or 0.120 or more, the liquid crystal material is inverted depending on the viewing angle direction as described in a fifth embodiment described later. This is because it has been confirmed that a phenomenon and a decrease in the contrast ratio occur. By setting the refractive index anisotropy Δn (550) of the liquid crystal material with respect to light having a wavelength of 550 nm to a range larger than 0.060 and smaller than 0.120, a phase difference corresponding to a viewing angle can be eliminated, and thus a liquid crystal display can be used. Naturally, a coloring phenomenon that occurs depending on the viewing angle on the screen can further improve a contrast change, a left-right inversion phenomenon, and the like.
[0067]
Here, by setting the refractive index anisotropy Δn (550) of the liquid crystal material to a light having a wavelength of 550 nm in a range of 0.070 or more and 0.095 or less, as described in a fifth embodiment described below, depending on the viewing angle. The phase difference can be more effectively eliminated. Therefore, a coloring phenomenon, a contrast change, a left-right inversion phenomenon, and the like that occur depending on the viewing angle on the liquid crystal display screen can be reliably improved.
[0068]
In the liquid crystal display device of the present invention, it is preferable that the inclination angle of the refractive index ellipsoid in the phase difference element is set in a range of 15 ° or more and 75 ° or less. By setting the inclination angle of the refractive index ellipsoid of the phase difference element in this manner, as described in a fifth embodiment described later, the phase difference change between the normal light and the extraordinary light that occurs according to the viewing angle described above is reduced. Compensation can be ensured by the phase difference element.
[0069]
In the liquid crystal display device of the present invention, the product (na−nb) × d of the difference between the main refractive indices na and nb of the phase difference element and the thickness d of the phase difference element is set in the range of 80 nm or more and 250 nm or less. It is preferable to set. By setting the product of the difference between the main refractive indices na and nb of the phase difference element and the thickness d of the phase difference element in this manner, as shown in a fifth embodiment described later, the normality generated according to the above-described viewing angle The phase difference change between the light and the extraordinary light can be reliably compensated for by the phase difference element.
[0070]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0071]
FIG. 1 is a sectional view showing a structure of a liquid crystal display device according to one embodiment of the present invention. This liquid crystal display device includes a liquid crystal cell 16 including a liquid crystal display element 1, a pair of retardation plates 2 and 3, and a pair of polarizing plates 4 and 5, and a driving circuit 17.
[0072]
In the liquid crystal display element 1, a liquid crystal layer 8 is sandwiched between a pair of electrode substrates 6 and 7 arranged opposite to each other. On one electrode substrate 6, a transparent electrode 10 made of ITO (indium tin oxide) is formed on the surface of a glass substrate (light transmitting substrate) 9 serving as a base on the liquid crystal layer 8 side, and an alignment film 11 is formed thereon. Is formed. In the other electrode substrate 7, a transparent electrode 13 made of ITO is formed on a surface of a glass substrate (translucent substrate) 12 serving as a base on a liquid crystal layer 8 side, and an alignment film 14 is formed thereon.
[0073]
Both transparent electrodes 10 and 11 are connected to a drive circuit 17. Although FIG. 1 shows a configuration for two pixels for simplicity, strip-shaped transparent electrodes 10 and 13 having a predetermined width are provided on almost all of the display portion of the liquid crystal display element 1. The transparent electrode 10 on one glass substrate 9 and the transparent electrode 13 on the other glass substrate 10 are formed so as to intersect each other when viewed from a direction perpendicular to the substrate surface. ing.
[0074]
The alignment films 11 and 14 are rubbed in advance so that the liquid crystal molecules in the liquid crystal layer 8 are twisted by about 90 °. The rubbing direction R1 of the alignment film 11 and the rubbing direction R2 of the alignment film 14 are set to directions orthogonal to each other, as shown in FIG.
[0075]
The two electrode substrates 6 and 7 are bonded to each other with a sealing resin 15, and a liquid crystal layer 8 is sealed in a space surrounded by the electrode substrates 6 and 7 and the sealing resin 15. Although details of the liquid crystal layer 8 will be described later, the normal refractive index no of the liquid crystal material in the liquid crystal layer 8 is adjusted so that the best characteristics can be obtained in combination with the phase difference compensation function of the phase difference plates 2 and 3. The degree of change with respect to the wavelength and the degree of change with respect to the wavelength of the extraordinary light refractive index ne are set in predetermined ranges.
[0076]
The retardation plates 2 and 3 are arranged one by one between the liquid crystal display element 1 and the polarizing plates 4 and 5 on both sides thereof. The retardation plates 2 and 3 are each formed by cross-linking a discotic liquid crystal in a tilted or hybrid orientation on a support made of a transparent organic polymer. Thereby, the retardation plates 2 and 3 in which the refractive index ellipsoids are inclined are obtained as described later.
[0077]
As a support material of the retardation plates 2 and 3, triacetyl cellulose (TAC) generally used for a polarizing plate is suitable, and a highly reliable retardation plate can be obtained. As other materials, a colorless and transparent organic polymer film excellent in environmental resistance and chemical resistance such as polycarbonate (PC) and polyethylene terephthalate (PET) is suitable.
[0078]
As shown in FIG. 3, the phase difference plates 2 and 3 have different main refractive indices na, nb and nc in three directions.
[0079]
The three main refractive indexes na, nb, and nc have a relationship of na = nc> nb. In this case, since there is only one optical axis, the retardation plates 2 and 3 have uniaxiality, and the refractive index anisotropy is negative.
[0080]
The direction of the main refractive index na coincides with the direction of the y-axis which is parallel to the surfaces of the phase difference plates 2 and 3 (parallel to the screen) among the orthogonal coordinate axes xyz. The direction of the main refractive index nb is from the direction of the z-axis perpendicular to the surfaces of the retardation plates 2 and 3 (the surface normal direction, perpendicular to the screen) in the direction of arrow A, with the direction of the main refractive index na as the axis. θ is inclined. The direction of the main refractive index nc is inclined by θ from the direction of the x-axis parallel to the surfaces of the phase difference plates 2 and 3 (parallel to the screen) with the direction of the main refractive index na as an axis. The inclination angle θ of the refractive index ellipsoid is preferably set to 15 ° ≦ θ ≦ 75 °. By setting the refractive index within this range, the phase difference compensating function of the phase difference plates 2 and 3 can be reliably obtained regardless of whether the inclination direction of the index ellipsoid is clockwise or counterclockwise. Here, the direction in which the direction of the main refractive index nb inclined in the direction that gives anisotropy to the phase difference plates 2 and 3 is projected on the surface of the phase difference plates 2 and 3 is D.
[0081]
The first retardation value of each of the retardation plates 2 and 3 is represented by a product (nc−na) × d of the difference between the main refractive indices na and nc (refractive index anisotropy Δn) and the thickness d of the retardation element. However, since na = nc, it is almost 0 nm. The second retardation value is represented by the product (na−nb) × d of the difference between the main refractive indices na and nb (refractive index anisotropy Δn) and the thickness d of the retardation element. It is preferable to set in the following range. By setting this range, the phase difference compensating function of the phase difference plates 2 and 3 can be reliably obtained.
[0082]
In an optically anisotropic body such as a liquid crystal or a retardation film (retardation film), the anisotropy of the main refractive indices na, nb, and nc in the three-dimensional direction is represented by a refractive index ellipsoid. The refractive index anisotropy Δn has different values depending on from which direction the refractive index anisotropic body is observed.
[0083]
In the liquid crystal display device of the present embodiment, the liquid crystal display element 1, the phase difference plates 2, 3, and the polarizing plates 4, 5, are arranged as shown in FIG.
[0084]
The polarizing plate 4 is arranged so that its absorption axis AX1 is parallel to the rubbing direction R1 of the alignment film 11 described above, and the polarizing plate 5 is arranged so that its absorption axis AX2 is parallel to the rubbing direction R2 of the alignment film 14 described above. It is arranged so that it becomes. In this liquid crystal display device, since the rubbing directions R1 and R2 are orthogonal to each other, the absorption axes AX1 and AX2 are also orthogonal to each other.
[0085]
The phase difference plate 2 is arranged so that the direction D (D1) shown in FIG. 3 is parallel to the rubbing direction R1 of the alignment film 11, and the phase difference plate 3 is oriented in the direction D (D2) shown in FIG. The alignment film 14 is arranged so as to be parallel to the rubbing direction R2.
[0086]
With the arrangement of the liquid crystal display element 1, the retardation plates 2, 3, and the polarizing plates 4, 5, a so-called normally white mode in which white light is displayed by transmitting light when the liquid crystal layer 8 is off without applying an on voltage. A liquid crystal display device is obtained.
[0087]
With respect to the arrangement of the phase difference plates 2 and 3, only one of the phase difference plates 2 and 3 may be arranged on one side of the liquid crystal display element 1, or both of the phase difference plates 2 and 3 may be arranged. It may be arranged on one side of the liquid crystal display element 2 so as to overlap. Furthermore, it is also possible to use three or more retardation plates.
[0088]
Next, the liquid crystal layer 8 will be described in detail.
[0089]
As described above, the degree of change of the normal refractive index no of the liquid crystal material of the liquid crystal material in the liquid crystal layer 8 with respect to the wavelength and the extraordinary light refraction so that the best characteristics can be obtained in combination with the phase difference compensation function of the phase difference plates 2 and 3. The degree of change of the rate ne with respect to the wavelength is set in a range in which coloring depending on the viewing angle does not occur on the display screen.
[0090]
Specifically, the degree of change of the normal refractive index no of the liquid crystal material with respect to the wavelength and the degree of change of the extraordinary refractive index ne of the liquid crystal material with respect to the wavelength are determined under the following conditions (1) or (2). Each is set so as to satisfy the conditions of at least one of the setting ranges of (1) and (2).
[0091]
(1) The extraordinary refractive index ne (450) of the liquid crystal material with respect to light having a wavelength of 450 nm, the extraordinary refractive index ne (550) with respect to light having a wavelength of 550 nm, and the extraordinary refractive index ne (650) with respect to light having a wavelength of 650 nm. A normal light refractive index no (450) for light of 450 nm, a normal light refractive index no (550) for light of 550 nm, and a normal light refractive index no (650) for light of 650 nm,
((No (450) -no (550)) / (no (550) -no (650))) / ((ne (450) -ne (550)) / (ne (550) -ne (650)) )) ≧ 1
If you have a relationship
{Circle around (1)} The degree of change in the normal light refractive index no (450) of the liquid crystal material for light having a wavelength of 450 nm, the normal light refractive index no (550) for light having a wavelength of 550 nm, and the normal light refractive index no (650) for light having a wavelength of 650 nm. To
1.65 ≦ ((no (450) −no (550)) / (no (550) −no (650)) ≦ 2.40
Set to the range.
[0092]
More preferably,
1.85 ≦ ((no (450) −no (550)) / (no (550) −no (650)) ≦ 2.20
Set to the range.
[0093]
{Circle over (2)} The degree of change of the extraordinary refractive index ne (450) for the light of wavelength 450 nm, the extraordinary refractive index ne (550) for the light of wavelength 550 nm, and the extraordinary refractive index ne (650) for the light of wavelength 650 nm of the liquid crystal material. To
1.70 ≦ ((ne (450) −ne (550)) / (ne (550) −ne (650)) ≦ 2.30
Set to the range.
[0094]
More preferably,
1.85 ≦ ((ne (450) −ne (550)) / (ne (550) −ne (650)) ≦ 2.10.
Set to the range.
[0095]
(2) The extraordinary light refractive index ne (450) for the light of wavelength 450 nm, the extraordinary light refractive index ne (550) for the light of wavelength 550 nm, the extraordinary light refractive index ne (650) for the light of wavelength 650 nm, and the wavelength of the liquid crystal material. A normal light refractive index no (450) for light of 450 nm, a normal light refractive index no (550) for light of 550 nm, and a normal light refractive index no (650) for light of 650 nm,
((No (450) -no (550)) / (no (550) -no (650))) / ((ne (450) -ne (550)) / (ne (550) -ne (650)) )) <1
If you have a relationship
{Circle around (1)} The degree of change in the normal light refractive index no (450) of the liquid crystal material for light having a wavelength of 450 nm, the normal light refractive index no (550) for light having a wavelength of 550 nm, and the normal light refractive index no (650) for light having a wavelength of 650 nm. To
1.00 ≦ ((no (450) −no (550)) / (no (550) −no (650)) ≦ 1.65
Set to the range.
[0096]
More preferably,
1.15 ≦ ((no (450) −no (550))) / (no (550) −no (650)) ≦ 1.45
Set to the range.
[0097]
{Circle over (2)} The degree of change of the extraordinary refractive index ne (450) for the light of wavelength 450 nm, the extraordinary refractive index ne (550) for the light of wavelength 550 nm, and the extraordinary refractive index ne (650) for the light of wavelength 650 nm of the liquid crystal material. To
1.20 ≦ ((ne (450) −ne (550)) / (ne (550) −ne (650)) ≦ 1.70
Set to the range.
[0098]
More preferably,
1.35 ≦ ((ne (450) −ne (550)) / (ne (550) −ne (650)) ≦ 1.60
Set to the range.
[0099]
With this configuration, in the liquid crystal display device of the present embodiment, the phase difference change between the normal light and the extraordinary light that occurs in the liquid crystal display element 1 according to the viewing angle is compensated by the phase difference plates 2 and 3, and the liquid crystal display screen is generated. Coloring depending on the viewing angle can be particularly effectively compensated for by the liquid crystal material of the liquid crystal layer 8. Therefore, coloring of the display screen depending on the viewing angle is effectively improved, and at the same time, the contrast change and the reversal phenomenon are also improved, so that a high-quality image can be obtained.
[0100]
Hereinafter, the liquid crystal display device of the present invention will be described with reference to more specific embodiments.
[0101]
(Embodiment 1)
In the first embodiment, as the liquid crystal material of the liquid crystal layer 8 in the liquid crystal display device shown in FIG. 1, the extraordinary light refractive index ne (450) for the liquid crystal material having a wavelength of 450 nm and the extraordinary light refractive index for the light having a wavelength of 550 nm are used. ne (550) and the extraordinary light refractive index ne (650) for light having a wavelength of 650 nm, the normal light refractive index no (450) for light having a wavelength of 450 nm, and the normal light refractive index no (550) and wavelength 650 nm for light having a wavelength of 550 nm. And the normal light refractive index no (650) for the light of
((No (450) -no (550)) / (no (550) -no (650))) / ((ne (450) -ne (550)) / (ne (550) -ne (650)) )) ≧ 1
age,
In addition, the degree of change of the normal light refractive index no (450) for light having a wavelength of 450 nm, the normal light refractive index no (550) for light having a wavelength of 550 nm, and the normal light refractive index no (650) for light having a wavelength of 650 nm is determined. ,
1.65 ≦ ((no (450) −no (550)) / (no (550) −no (650)) ≦ 2.40
The one set in the range was used.
[0102]
This liquid crystal material was prepared by blending a material system represented by the following structural formula.
[0103]
Embedded image

[0104]
The cell thickness of the liquid crystal cell 16 (the thickness of the liquid crystal layer 8) was 5 μm, and five liquid crystal display devices (samples # 11 to # 15) shown in Table 1 below were produced.
[0105]
As the retardation plates 2 and 3, a discotic liquid crystal is applied to a transparent support (for example, triacetyl cellulose (TAC) or the like), and the discotic liquid crystal is obliquely oriented and crosslinked to form a first retardation value ( nc−na) × d is 0 nm, the second retardation value (na−nb) × d is 100 nm, and the direction of the main refractive index nb shown in FIG. 3 is from the z-axis direction on the xyz coordinate axis to the direction of arrow A A refractive index ellipsoid having a main refractive index nc inclined by about 20 ° from the x-axis direction in the direction of arrow B by about 20 ° was manufactured.
[0106]
Further, for comparison, in the liquid crystal display device shown in the liquid crystal display device of FIG.
In the same manner as in this embodiment except that ((no (450) -no (550)) / (no (550) -no (650)) of 1.55 and 2.50 were used, the following Table 1 was used. The two liquid crystal display devices shown (Comparative Samples # 100 and # 101) were produced.
[0107]
Table 1 below shows the results of a visual test performed on the samples # 11 to # 15 and the comparative samples # 100 and # 101 under white light. In Table 1 below and Tables 2 to 4 of Embodiments 2 to 4 described below, ○ indicates no coloring, Δ indicates coloring enough to endure use, and X indicates coloration not enduring use.
[0108]
[Table 1]

[0109]
As shown in Table 1 above, with respect to the samples # 12 to # 14 of the present embodiment, coloring was not observed from any direction at a viewing angle of 70 °, and good image quality was obtained. Therefore,
1.85 ≦ ((no (450) −no (550)) / (no (550) −no (650)) ≦ 2.20
It is understood that particularly excellent characteristics can be obtained in the range.
[0110]
Further, with respect to the samples # 11 and # 15 of the present embodiment, no coloring was confirmed from any direction up to a viewing angle of 50 °, and good image quality was obtained. At a viewing angle of 60 °, slight coloring was observed when viewed from the left and right directions, but the coloring was such that it could be used.
[0111]
On the other hand, for Comparative Samples # 100 and # 101, yellow to orange coloring that was unusable when used in a horizontal direction even at a viewing angle of 50 ° was confirmed.
[0112]
Further, samples # 11 to # 15 of the present embodiment and comparative samples # 100 and # 101 were used in the same manner as the retardation plates 2 and 3 except that a discotic liquid crystal was applied to a transparent support and hybrid alignment was performed. Similar results were obtained for the manufactured liquid crystal display device.
[0113]
(Embodiment 2)
In the second embodiment, in the liquid crystal display device shown in FIG. 1, as a liquid crystal material of the liquid crystal layer 8, an extraordinary refractive index ne (450) for a liquid crystal material having a wavelength of 450 nm and an extraordinary refractive index for a light having a wavelength of 550 nm are used. ne (550) and the extraordinary light refractive index ne (650) for light having a wavelength of 650 nm, the normal light refractive index no (450) for light having a wavelength of 450 nm, and the normal light refractive index no (550) and wavelength 650 nm for light having a wavelength of 550 nm. And the normal light refractive index no (650) for the light of
((No (450) -no (550)) / (no (550) -no (650))) / ((ne (450) -ne (550)) / (ne (550) -ne (650)) )) ≧ 1
age,
In addition, the degree of change of the extraordinary light refractive index ne (450) with respect to light having a wavelength of 450 nm, the extraordinary light refractive index ne (550) with respect to light having a wavelength of 550 nm, and the extraordinary refractive index ne (650) with respect to light having a wavelength of 650 nm of the liquid crystal material. ,
1.70 ≦ ((ne (450) −ne (550)) / (ne (550) −ne (650)) ≦ 2.30
The one set in the range was used.
[0114]
This liquid crystal material was adjusted by blending the material system described in the first embodiment.
[0115]
The cell thickness of the liquid crystal cell 16 was 5 μm, and five liquid crystal display devices (samples # 21 to # 25) shown in Table 2 below were produced.
[0116]
As the retardation plates 2 and 3, a discotic liquid crystal is applied to a transparent support (for example, triacetyl cellulose (TAC) or the like), and the discotic liquid crystal is obliquely oriented and crosslinked to form a first retardation value ( nc−na) × d is 0 nm, the second retardation value (na−nb) × d is 100 nm, and the direction of the main refractive index nb shown in FIG. 3 is from the z-axis direction on the xyz coordinate axis to the direction of arrow A A refractive index ellipsoid having a main refractive index nc inclined by about 20 ° from the x-axis direction in the direction of arrow B by about 20 ° was manufactured.
[0117]
Further, for comparison, in the liquid crystal display device shown in the liquid crystal display device of FIG.
In the same manner as in this embodiment except that ((ne (450) -ne (550)) / (ne (550) -ne (650)) was 1.60 and 2.40, the following Table 2 was used. The two liquid crystal display devices shown (comparative samples # 200 and # 201) were produced.
[0118]
Table 2 below shows the results of a visual test performed on the samples # 21 to # 25 and the comparative samples # 200 and # 201 under white light.
[0119]
[Table 2]

[0120]
As shown in Table 2 above, with respect to the samples # 22 to # 24 of the present embodiment, coloring was not observed from any direction at a viewing angle of 70 °, and good image quality was obtained. Therefore,
1.85 ≦ ((ne (450) −ne (550)) / (ne (550) −ne (650)) ≦ 2.10.
It is understood that particularly excellent characteristics can be obtained in the range.
[0121]
Further, with respect to the samples # 21 and # 25 of the present embodiment, no coloring was confirmed from any direction up to a viewing angle of 50 °, and good image quality was obtained. At a viewing angle of 60 °, slight coloring was observed when viewed from the left and right directions, but the coloring was such that it could be used.
[0122]
On the other hand, with respect to Comparative Samples # 200 and # 201, coloring from yellow to orange that was unusable when viewed from the left and right directions even at a viewing angle of 50 ° was confirmed.
[0123]
Further, samples # 21 to # 25 of the present embodiment and comparative samples # 200 and # 201 were formed in the same manner as the retardation plates 2 and 3 except that a discotic liquid crystal was applied to a transparent support and hybrid alignment was performed. Similar results were obtained for the manufactured liquid crystal display device.
[0124]
(Embodiment 3)
In the third embodiment, in the liquid crystal display device shown in FIG. 1, as a liquid crystal material of the liquid crystal layer 8, an extraordinary light refractive index ne (450) for light having a wavelength of 450 nm and an extraordinary refractive index for light having a wavelength of 550 nm are used. ne (550) and the extraordinary light refractive index ne (650) for light having a wavelength of 650 nm, the normal light refractive index no (450) for light having a wavelength of 450 nm, and the normal light refractive index no (550) and wavelength 650 nm for light having a wavelength of 550 nm. And the normal light refractive index no (650) for the light of
((No (450) -no (550)) / (no (550) -no (650))) / ((ne (450) -ne (550)) / (ne (550) -ne (650)) )) <1
age,
In addition, the degree of change of the normal light refractive index no (450) for light having a wavelength of 450 nm, the normal light refractive index no (550) for light having a wavelength of 550 nm, and the normal light refractive index no (650) for light having a wavelength of 650 nm is determined. ,
1.00 ≦ ((no (450) −no (550)) / (no (550) −no (650)) ≦ 1.65
The one set in the range was used.
[0125]
This liquid crystal material was adjusted by blending the material system described in the first embodiment.
[0126]
The cell thickness of the liquid crystal cell 16 was 5 μm, and five liquid crystal display devices (samples # 31 to # 35) shown in Table 3 below were produced.
[0127]
As the retardation plates 2 and 3, a discotic liquid crystal is applied to a transparent support (for example, triacetyl cellulose (TAC) or the like), and the discotic liquid crystal is obliquely oriented and crosslinked to form a first retardation value ( nc−na) × d is 0 nm, the second retardation value (na−nb) × d is 100 nm, and the direction of the main refractive index nb shown in FIG. 3 is from the z-axis direction on the xyz coordinate axis to the direction of arrow A A refractive index ellipsoid having a main refractive index nc inclined by about 20 ° from the x-axis direction in the direction of arrow B by about 20 ° was manufactured.
[0128]
Further, for comparison, in the liquid crystal display device shown in the liquid crystal display device of FIG.
In the same manner as in the present embodiment, except that ((no (450) -no (550)) / (no (550) -no (650))) of 0.90 and 1.75 were used, the following Table 3 was used. The two liquid crystal display devices shown (comparative samples # 300 and # 301) were produced.
[0129]
Table 3 below shows the results of a visual test performed on the samples # 31 to # 35 and the comparative samples # 300 and # 301 under white light.
[0130]
[Table 3]

[0131]
As shown in Table 3, with respect to the samples # 32 to # 34 of the present embodiment, no coloring was observed from any direction at a viewing angle of 70 °, and good image quality was obtained. Therefore,
1.15 ≦ ((no (450) −no (550))) / (no (550) −no (650)) ≦ 1.45
It is understood that particularly excellent characteristics can be obtained in the range.
[0132]
Further, with respect to the samples # 31 and # 35 of the present embodiment, no coloring was confirmed from any direction up to a viewing angle of 50 °, and good image quality was obtained. At a viewing angle of 60 °, slight coloring was observed when viewed from the left and right directions, but the coloring was such that it could be used.
[0133]
On the other hand, in Comparative Samples # 300 and # 301, even at a viewing angle of 50 °, coloring from yellow to orange that was unusable when viewed from the left and right directions was confirmed.
[0134]
Further, except that discotic liquid crystals were applied to transparent supports as the retardation plates 2 and 3 to perform hybrid alignment, the same as the samples # 31 to # 35 of the present embodiment and the comparative samples # 300 and # 301. Similar results were obtained for the manufactured liquid crystal display device.
[0135]
(Embodiment 4)
In the fourth embodiment, in the liquid crystal display device shown in FIG. 1, as the liquid crystal material of the liquid crystal layer 8, the extraordinary light refractive index ne (450) for the liquid crystal material having a wavelength of 450 nm and the extraordinary light refractive index for the light having a wavelength of 550 nm are used. ne (550) and the extraordinary light refractive index ne (650) for light having a wavelength of 650 nm, the normal light refractive index no (450) for light having a wavelength of 450 nm, and the normal light refractive index no (550) and wavelength 650 nm for light having a wavelength of 550 nm. And the normal light refractive index no (650) for the light of
((No (450) -no (550)) / (no (550) -no (650))) / ((ne (450) -ne (550)) / (ne (550) -ne (650)) )) <1
age,
In addition, the degree of change of the extraordinary light refractive index ne (450) with respect to light having a wavelength of 450 nm, the extraordinary light refractive index ne (550) with respect to light having a wavelength of 550 nm, and the extraordinary refractive index ne (650) with respect to light having a wavelength of 650 nm of the liquid crystal material. ,
1.20 ≦ ((ne (450) −ne (550)) / (ne (550) −ne (650)) ≦ 1.70
The one set in the range was used.
[0136]
This liquid crystal material was adjusted by blending the material system described in the first embodiment.
[0137]
The cell thickness of the liquid crystal cell 16 was 5 μm, and five liquid crystal display devices (samples # 41 to # 45) shown in Table 4 below were produced.
[0138]
As the retardation plates 2 and 3, a discotic liquid crystal is applied to a transparent support (for example, triacetyl cellulose (TAC) or the like), and the discotic liquid crystal is obliquely oriented and crosslinked to form a first retardation value ( nc−na) × d is 0 nm, the second retardation value (na−nb) × d is 100 nm, and the direction of the main refractive index nb shown in FIG. 3 is from the z-axis direction on the xyz coordinate axis to the direction of arrow A A refractive index ellipsoid having a main refractive index nc inclined by about 20 ° from the x-axis direction in the direction of arrow B by about 20 ° was manufactured.
[0139]
Further, for comparison, in the liquid crystal display device shown in the liquid crystal display device of FIG.
In the same manner as in this embodiment except that ((ne (450) -ne (550)) / (ne (550) -ne (650))) was 1.10 and 1.80, the following Table 2 was used. The two liquid crystal display devices shown (Comparative Samples # 400 and # 401) were produced.
[0140]
Table 4 below shows the results of a visual test performed on the samples # 41 to # 45 and the comparative samples # 400 and # 401 under white light.
[0141]
[Table 4]

[0142]
As shown in Table 4 above, with respect to the samples # 42 to # 44 of the present embodiment, no coloring was observed from any direction at a viewing angle of 70 °, and good image quality was obtained. Therefore,
1.35 ≦ ((ne (450) −ne (550)) / (ne (550) −ne (650)) ≦ 1.60
It is understood that particularly excellent characteristics can be obtained in the range.
[0143]
Further, with respect to the samples # 41 and # 45 of the present embodiment, no coloring was confirmed from any direction up to a viewing angle of 50 °, and good image quality was obtained. At a viewing angle of 60 °, slight coloring was observed when viewed from the left and right directions, but the coloring was such that it could be used.
[0144]
On the other hand, with respect to Comparative Samples # 400 and # 401, coloring from yellow to orange that was unusable when viewed from the left and right directions even at a viewing angle of 50 ° was confirmed.
[0145]
Furthermore, samples # 41 to # 45 of the present embodiment and comparative samples # 400 and # 401 were used, except that discotic liquid crystals were applied to transparent supports as the phase difference plates 2 and 3 to perform hybrid alignment. Similar results were obtained for the manufactured liquid crystal display device.
[0146]
(Embodiment 5)
In the fifth embodiment, in the liquid crystal display device shown in FIG. Using the set materials, three liquid crystal display devices (samples # 51 to # 53) were manufactured with the liquid crystal cell 16 having a cell thickness of 5 μm. Table 5 below shows the degree of change in the normal light refractive index no and the degree of change in the extraordinary light refractive index ne of each sample.
[0147]
[Table 5]

[0148]
The retardation plates 2 and 3 used were the same as those in the first embodiment in which the discotic liquid crystal was tilted and aligned.
[0149]
Further, for comparison, in the liquid crystal display device shown in the liquid crystal display device of FIG. 1, the liquid crystal material of the liquid crystal layer 8 has a refractive index anisotropy Δn (550) of 0.060, 0.120 for light having a wavelength of 550 nm. The two liquid crystal display devices (Comparative Samples # 501 and # 502) were produced in the same manner as in the present embodiment except that the liquid crystal display device set in Example 1 was used.
[0150]
With respect to the samples # 51 to # 53 and the comparative samples # 501 and # 502, the viewing angle dependence of the liquid crystal display device was measured using a measurement system including the light receiving element 21, the amplifier 22, and the recording device 23 as shown in FIG. did.
[0151]
In this measurement system, the liquid crystal cell 16 of the liquid crystal display device is installed such that the surface 16a on the glass substrate 9 side is located at the position of the reference plane xy on the orthogonal coordinate axis xyz.
[0152]
The light receiving element 21 is an element capable of receiving light at a constant three-dimensional light receiving angle, and is located at a predetermined distance from the coordinate origin in a direction forming an angle φ (viewing angle) with respect to the z direction perpendicular to the surface 16 a of the liquid crystal cell 16. Are located in
[0153]
At the time of measurement, the liquid crystal cell 16 installed in the measurement system is irradiated with monochromatic light having a wavelength of 550 nm from the surface opposite to the surface 16a. Thereby, a part of the monochromatic light transmitted through the liquid crystal cell 16 is incident on the light receiving element 21. After the output of the light receiving element 21 is amplified to a predetermined level by the amplifier 22, the output is recorded by the recording device 23 having a waveform memory, a recorder, and the like.
[0154]
In this measurement system, the samples # 51 to # 53 of this embodiment and the comparative samples # 501 and # 502 are installed, and the voltage applied to each liquid crystal display device and the light reception when the light receiving element 21 is fixed at a fixed angle φ. The relationship with the output level of the element 21 was measured.
[0155]
Here, assuming that the x direction is on the lower side of the screen and the y direction is on the left side of the screen, the arrangement position of the light receiving element 21 is shifted upward, rightward, and leftward so that the angle φ is 50 °. The measurement was carried out while changing the respective conditions.
[0156]
FIGS. 6A to 6C show the measurement results of the samples # 51 to # 53 of the present embodiment, and FIGS. 7A to 7C show the measurement results of the comparison samples # 501 and # 502. FIGS. 6A to 6C and FIGS. 7A to 7C are graphs showing light transmittance (transmittance-liquid crystal applied voltage characteristics) with respect to a voltage applied to each liquid crystal display device. FIGS. 6A and 7A show the results of measurement from above in FIG. 2, and FIGS. 6B and 7B show the results of measurement from the right in FIG. FIG. 6 (c) and FIG. 7 (c) show the results of measurement from the left in FIG.
[0157]
6 (a) to 6 (c), curves L1, L4 and L7 indicated by alternate long and short dash lines indicate sample # 51 using a liquid crystal material of Δn (550) = 0.070 in the liquid crystal layer 8, and are indicated by solid lines. Curves L2, L5, and L8 shown show sample # 52 using a liquid crystal material of Δn (550) = 0.080 for the liquid crystal layer 8, and curves L3, L6, and L9 shown by dotted lines show Δn ( Sample # 53 using a liquid crystal material of (550) = 0.095 is shown. 7A to 7C, curves L10, L12, and L14 shown by solid lines show a comparative sample # 501 using a liquid crystal material of Δn (550) = 0.060 for the liquid crystal layer 8, and are shown by dotted lines. Curves L11, L13, and L15 show a comparative sample # 502 using a liquid crystal material of Δn (550) = 0.120 for the liquid crystal layer 8.
[0158]
Regarding the transmittance in the upward direction and the liquid crystal applied voltage characteristic, in samples # 51 to # 53 of the present embodiment, as shown by L1 to L3 in FIG. It was confirmed that it went down. On the other hand, in the comparative sample # 502, as shown by L11 in FIG. 7A, the transmittance does not decrease sufficiently even when the voltage is increased, and in the comparative sample # 501, the transmittance is shown by L10 in FIG. 7A. As described above, an inversion phenomenon in which the transmittance once decreased with increasing voltage and then increased again was observed.
[0159]
Similarly, regarding the transmittance in the right direction-the voltage applied to the liquid crystal, in the samples # 51 to # 53 of the present embodiment, as shown by L4 to L6 in FIG. It was confirmed that the rate decreased to almost zero. On the other hand, in the comparative sample # 501, as shown in L12 of FIG. 7 (b), the transmittance decreases to almost 0 as the voltage increases, but in the comparative sample # 502, L13 in FIG. As shown in FIG. 5, the reversal phenomenon was observed in which the transmittance once decreased with increasing voltage and then increased again.
[0160]
Similarly, with respect to the transmittance in the left direction and the voltage applied to the liquid crystal, in the samples # 51 to # 53 of the present embodiment, as shown by L7 to L9 in FIG. It was confirmed that the rate decreased to almost zero. On the other hand, in the comparative sample # 501, as shown in L14 of FIG. 7 (c), the transmittance decreases to almost near 0 as the voltage increases, but in the comparative sample # 502, the transmittance of L15 in FIG. 7 (c) decreases. As shown in FIG. 5, the reversal phenomenon was observed in which the transmittance once decreased with increasing voltage and then increased again.
[0161]
Further, a visual test was performed on the samples # 51 to # 53 and the comparative samples # 501 and # 502 under white light, and the visual angles of the samples # 51 to # 53 and the comparative sample # 501 of the present embodiment were determined. No coloring was observed from any direction up to 50 °, and good image quality was obtained.
[0162]
On the other hand, for Comparative Sample # 502, coloring from yellow to orange was confirmed when viewed from the left and right directions at a viewing angle of 50 °.
[0163]
From the above results, as the liquid crystal material of the liquid crystal layer 8, the liquid crystal display device (sample) of this embodiment in which the refractive index anisotropy Δn (550) for light having a wavelength of 550 nm was set to 0.070, 0.080, and 0.095. In # 51 to # 53), as shown in FIGS. 6 (a) to 6 (c), as the voltage is applied, the transmittance is sufficiently reduced and no reversal phenomenon is observed, so that the viewing angle is increased. Since no coloring phenomenon is observed, it can be seen that the display quality of the liquid crystal display device is remarkably improved.
[0164]
On the other hand, in a liquid crystal display device (comparative samples # 501 and # 502) in which the refractive index anisotropy Δn (550) for light having a wavelength of 550 nm is set to 0.060 and 0.120 as the liquid crystal material of the liquid crystal layer 8. 7 (a) to 7 (c) that the viewing angle dependency is not sufficiently improved.
[0165]
Further, the same as the samples # 51 to # 53 of the present embodiment and the comparative samples # 501 and # 502 except that the discotic liquid crystal was applied to the transparent supports as the retardation plates 2 and 3 and hybrid alignment was performed. Similar results were obtained for the manufactured liquid crystal display device.
[0166]
As a result of examining the dependence of the transmittance-liquid crystal applied voltage characteristic on the inclination angle θ by changing the inclination angle θ of the refractive index ellipsoids of the phase difference plates 2 and 3, the result was in the range of 15 ° ≦ θ ≦ 75 °. If so, basically the same results as described above were obtained irrespective of the alignment state of the discotic liquid crystal in the retardation plates 2 and 3. On the other hand, when the inclination angle was less than 15 ° or more than 75 °, it was confirmed that the viewing angle in the opposite viewing angle direction was not enlarged.
[0167]
As a result of examining the dependence of the transmittance-liquid crystal applied voltage characteristic on the second retardation value by changing the second retardation value (na−nb) × d of the phase difference plates 2 and 3, When the retardation value is in the range of not less than 80 nm and not more than 250 nm, basically the same results as described above were obtained irrespective of the alignment state of the discotic liquid crystal in the retardation films 2 and 3. On the other hand, when the second retardation value was less than 80 nm or more than 250 nm, it was confirmed that the viewing angle in the horizontal direction (lateral direction) was not expanded.
[0168]
Further, based on the results of the visual tests of the comparative samples # 501 and # 502, in the liquid crystal display device shown in the liquid crystal display device of FIG. Three liquid crystal display devices (samples # 54 to # 56) were produced in the same manner as in the present embodiment, except that those having the properties Δn (550) set to 0.065, 0.100, and 0.115 were used.
[0169]
When these samples # 54 to # 56 are installed in the measurement system shown in FIG. 5 and the light receiving element 21 is fixed at a fixed angle φ, the voltage applied to each liquid crystal display device and the output level of the light receiving element 21 Was measured, and a visual test was performed under white light.
[0170]
As a result, in the samples # 55 and # 56 of the present embodiment in which the refractive index anisotropy Δn (550) with respect to the light having a wavelength of 550 nm was set to 0.100 and 0.115, the left and right sides when the angle φ = 50 ° were set. When the voltage was increased in the direction, a slight increase in transmittance was observed. However, the reversal phenomenon did not occur visually, and such an increase in transmittance was acceptable for use. In the upward direction, a result without any problem was obtained. On the other hand, in the sample # 54 of the present embodiment in which the refractive index anisotropy Δn (550) for the light having the wavelength of 550 nm is set to 0.065, similarly to the comparative sample # 501, the voltage is increased in the upward direction. As a result, there was an inversion phenomenon in which the transmittance once decreased and then increased again. However, the degree of increase in the transmittance was smaller than that of the comparative sample # 501 (L10) shown in FIG. It was tolerable. In the left-right direction, a result without any problem was obtained.
[0171]
Further, in the visual inspection, slight coloring from yellow to orange was confirmed for the samples # 55 and # 56 of the present embodiment, but the coloring was not a problem. On the other hand, it was confirmed that the sample # 54 of the present embodiment exhibited a slight bluish color, but the bluish color was not a problem.
[0172]
Further, with respect to Sample # 54 and Comparative Sample # 501, a voltage of about 1 V was applied, and the transmittance of the surface of the liquid crystal cell 16 in the normal direction at the time of white display was measured. As a result, the transmittance of Comparative Sample # 501 was reduced to such an extent that it could not withstand use. On the other hand, in the sample # 54 of the present embodiment, a slight decrease in transmittance was confirmed, but it was of a level that could be used.
[0173]
【The invention's effect】
As described above in detail, in the case of the present invention, the three main refractive indices na, nb, and nc of the refractive index ellipsoid have a relationship of na = nc> nb, and the main refractive indices na and n are substantially parallel to the surface. The direction of the main refractive index nb is inclined clockwise or counterclockwise from the normal direction of the surface with one direction of nc as an axis, and the other direction of the main refractive indexes na and nc is substantially parallel to the surface. By using a phase difference plate that is inclined clockwise or counterclockwise from an appropriate direction, it is possible to compensate for a change in the phase difference of the liquid crystal display element. In addition, at least one of the degree of change of the normal refractive index no of the liquid crystal material of the liquid crystal material with respect to the wavelength and the degree of change of the extraordinary refractive index ne with respect to the wavelength is set in a range in which screen coloring depending on the viewing angle does not occur. This makes it possible to further prevent the coloring of the liquid crystal display screen depending on the viewing angle, and further, regarding the reversal phenomenon and the reduction of the contrast ratio in the anti-viewing angle direction, more than the case where only the compensation function of the retardation plate is used. Can be improved.
[0174]
further,In the present inventionDepends on the viewing angle by setting the degree of change of the refractive index of the liquid crystal material with respect to the wavelength in view of the fact that there are different materials in which the range in which screen coloring does not occur depending on the viewing angle is different. It is possible to further prevent the liquid crystal display screen from being colored, and to further reduce the reversal phenomenon and the decrease in the contrast ratio in the anti-viewing angle direction as compared with the case where only the compensation function of the retardation plate is used.
[0175]
In particular,In the present inventionWith a viewing angle of 60 °, which exceeds the viewing angle of 50 ° required for a normal liquid crystal display device, it is possible to suppress the coloring of the liquid crystal display screen to such an extent that the liquid crystal display screen can be sufficiently used in all directions.
[0176]
further,In the present inventionIn a liquid crystal display device having a wider viewing angle of 70 °, a state in which the liquid crystal display screen has no coloring phenomenon in any direction can be realized.
[0177]
In the present inventionIs to set the refractive index anisotropy Δn (550) for light having a wavelength of 550 nm in a range larger than 0.060 and smaller than 0.120 to eliminate a phase difference generated in a liquid crystal display element according to a viewing angle. it can. Accordingly, the coloring phenomenon which occurs depending on the viewing angle on the liquid crystal display screen can naturally be improved further, such as the contrast change and the left-right inversion phenomenon.
[0178]
further,In the present inventionIs set by setting the refractive index anisotropy Δn (550) for light having a wavelength of 550 nm in a range of 0.070 or more and 0.095 or less.ThanFurther, the phase difference generated according to the viewing angle can be effectively eliminated. Therefore, a coloring phenomenon, a contrast change, a left-right inversion phenomenon, and the like that occur depending on the viewing angle on the liquid crystal display screen can be more reliably improved.
[0179]
In the present inventionBy setting the inclination angle of the refractive index ellipsoid in the range of 15 ° or more and 75 ° or less, the function of compensating for the phase difference by the phase difference element can be reliably obtained, so that the visibility is surely improved. Can be.
[0180]
In the present inventionIs determined by setting the product (na−nb) × d of the difference between the main refractive indices na and nb of the phase difference element and the thickness d of the phase difference element in the range of 80 nm or more and 250 nm or less, Since the phase difference compensation function can be reliably obtained, the visibility can be reliably improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration of a liquid crystal display device according to an embodiment of the present invention.
FIG. 2 is a diagram showing a relationship between a rubbing direction of an alignment film and a viewing angle direction in the liquid crystal display device of FIG.
FIG. 3 is a perspective view showing a direction of a main refractive index of a retardation plate in the liquid crystal display device of FIG.
FIG. 4 is a perspective view showing an optical arrangement of a liquid crystal display element, a polarizing plate, and a retardation plate in the liquid crystal display device of FIG.
FIG. 5 is a perspective view showing a measurement system for measuring the viewing angle dependency of the liquid crystal display device according to the fifth embodiment.
FIG. 6 is a graph showing transmittance-liquid crystal applied voltage characteristics of the liquid crystal display device of the fifth embodiment.
FIG. 7 is a graph showing transmittance-liquid crystal applied voltage characteristics of a liquid crystal display device of a comparative example.
FIG. 8 is a schematic diagram showing a twisted orientation of liquid crystal molecules in a TN liquid crystal display element.
[Explanation of symbols]
1 Liquid crystal display device
2, 3 retardation plate
4,5 polarizing plate
6, 7 electrode substrate
8 Liquid crystal layer
9,12 translucent substrate
10, 13 Transparent electrode
11, 14 alignment film
15 Seal resin
16 liquid crystal cell
17 Drive circuit

Claims (4)

A liquid crystal display element in which a liquid crystal layer is sandwiched between a pair of substrates each having an electrode layer and an alignment film; a pair of polarizers sandwiching both sides of the liquid crystal display element; at least one polarizer and the liquid crystal display element possess at least one of a phase difference element provided between,
The three main refractive indices na, nb, and nc of the refractive index ellipsoid of the phase difference element have a relationship of na = nc> nb, and among the main refractive indexes na and nc substantially parallel to the surface of the phase difference element. With one direction as an axis, the direction of the main refractive index nb is inclined clockwise or counterclockwise from the normal direction of the surface, and the other direction of the main refractive indices na and nc is from a direction substantially parallel to the surface. A method for manufacturing a liquid crystal display device that is inclined clockwise or counterclockwise ,
The extraordinary light refractive index ne (450) for the light of wavelength 450 nm, the extraordinary refractive index ne (550) for the light of wavelength 550 nm, and the extraordinary refractive index ne (650) for the light of wavelength 650 nm of the liquid crystal material in the liquid crystal layer The normal light refractive index no (450) for light having a wavelength of 450 nm, the normal light refractive index no (550) for light having a wavelength of 550 nm, and the normal light refractive index no (650) for light having a wavelength of 650 nm are as follows:
((No (450) -no (550)) / (no (550) -no (650))) / ((ne (450) -ne (550)) / (ne (550) -ne (650)) ) ≧ 1
And,
1.65 ≦ (no (450) −no (550)) / (no (550) −no (650)) ≦ 2.40
A method for manufacturing a liquid crystal display device, comprising the step of blending and adjusting the liquid crystal material in the range described above . A liquid crystal display element in which a liquid crystal layer is sandwiched between a pair of substrates each having an electrode layer and an alignment film; a pair of polarizers sandwiching both sides of the liquid crystal display element; at least one polarizer and the liquid crystal display element And at least one retardation element provided between
The three main refractive indices na, nb, and nc of the refractive index ellipsoid of the phase difference element have a relationship of na = nc> nb, and among the main refractive indexes na and nc substantially parallel to the surface of the phase difference element. With one direction as an axis, the direction of the main refractive index nb is inclined clockwise or counterclockwise from the normal direction of the surface, and the other direction of the main refractive indices na and nc is from a direction substantially parallel to the surface. A method for manufacturing a liquid crystal display device that is inclined clockwise or counterclockwise,
The extraordinary light refractive index ne (450) for the light of wavelength 450 nm, the extraordinary refractive index ne (550) for the light of wavelength 550 nm, and the extraordinary refractive index ne (650) for the light of wavelength 650 nm of the liquid crystal material in the liquid crystal layer. The normal light refractive index no (450) for light having a wavelength of 450 nm, the normal light refractive index no (550) for light having a wavelength of 550 nm, and the normal light refractive index no (650) for light having a wavelength of 650 nm are as follows:
((No (450) -no (550)) / (no (550) -no (650))) / ((ne (450) -ne (550)) / (ne (550) -ne (650)) ) ≧ 1
And,
The degree of change of the extraordinary light refractive index ne (450) for the light of wavelength 550 nm, the extraordinary light refractive index ne (550) for the light of wavelength 550 nm, and the extraordinary light refractive index ne (650) for the light of wavelength 650 nm of the liquid crystal material is as follows:
1.70 ≦ (ne (450) −ne (550)) / (ne (550) −ne (650)) ≦ 2.30
A method for manufacturing a liquid crystal display device, comprising a step of blending and adjusting the liquid crystal material in the range described above. A liquid crystal display element in which a liquid crystal layer is sandwiched between a pair of substrates each having an electrode layer and an alignment film; a pair of polarizers sandwiching both sides of the liquid crystal display element; at least one polarizer and the liquid crystal display element And at least one retardation element provided between
The three main refractive indices na, nb, and nc of the refractive index ellipsoid of the phase difference element have a relationship of na = nc> nb, and among the main refractive indexes na and nc substantially parallel to the surface of the phase difference element. With one direction as an axis, the direction of the main refractive index nb is inclined clockwise or counterclockwise from the normal direction of the surface, and the other direction of the main refractive indices na and nc is from a direction substantially parallel to the surface. A method for manufacturing a liquid crystal display device that is inclined clockwise or counterclockwise,
The extraordinary light refractive index ne (450) for the light of wavelength 450 nm, the extraordinary refractive index ne (550) for the light of wavelength 550 nm, and the extraordinary refractive index ne (650) for the light of wavelength 650 nm of the liquid crystal material in the liquid crystal layer. The normal light refractive index no (450) for light having a wavelength of 450 nm, the normal light refractive index no (550) for light having a wavelength of 550 nm, and the normal light refractive index no (650) for light having a wavelength of 650 nm are as follows:
((No (450) -no (550)) / (no (550) -no (650))) / ((ne (450) -ne (550)) / (ne (550) -ne (650)) ) <1
And,
1.00 ≦ (no (450) −no (550)) / (no (550) −no (650)) ≦ 1.65
A method for manufacturing a liquid crystal display device, comprising a step of blending and adjusting the liquid crystal material in the range described above. A liquid crystal display element in which a liquid crystal layer is sandwiched between a pair of substrates each having an electrode layer and an alignment film; a pair of polarizers sandwiching both sides of the liquid crystal display element; at least one polarizer and the liquid crystal display element And at least one retardation element provided between
The three main refractive indices na, nb, and nc of the refractive index ellipsoid of the phase difference element have a relationship of na = nc> nb, and among the main refractive indexes na and nc substantially parallel to the surface of the phase difference element. With one direction as an axis, the direction of the main refractive index nb is inclined clockwise or counterclockwise from the normal direction of the surface, and the other direction of the main refractive indices na and nc is from a direction substantially parallel to the surface. A method for manufacturing a liquid crystal display device that is inclined clockwise or counterclockwise,
The extraordinary light refractive index ne (450) for the light of wavelength 450 nm, the extraordinary refractive index ne (550) for the light of wavelength 550 nm, and the extraordinary refractive index ne (650) for the light of wavelength 650 nm of the liquid crystal material in the liquid crystal layer. The normal light refractive index no (450) for light having a wavelength of 450 nm, the normal light refractive index no (550) for light having a wavelength of 550 nm, and the normal light refractive index no (650) for light having a wavelength of 650 nm are as follows:
((No (450) -no (550)) / (no (550) -no (650))) / ((ne (450) -ne (550)) / (ne (550) -ne (650)) ) <1
And,
1.20 ≦ (ne (450) −ne (550)) / (ne (550) −ne (650)) ≦ 1.70
A method for manufacturing a liquid crystal display device, comprising a step of blending and adjusting the liquid crystal material in the range described above.

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