JP3569296B2 - Liquid crystal electro-optical element - Google Patents

Description

【００１０】
で表される紫外線硬化型モノマ−を液晶：モノマー＝９５：５（重量比）で混合し、パネル中に真空下で封入した。さらにモノマーを高分子にするために、封入したパネルを４０度の雰囲気下で、合計照射量が５００ｍＪ／ｃｍ^２になるように紫外線を１５分間照射した。このようにして得られた液晶表示素子の電界が印加されていないときの断面の概略図を図２に示す。
【００１１】
この様にして得られた液晶表示素子は、電圧が印加されていないときはほぼ透明で光を透過し、画素部分は鏡状である。電圧を印加すると白濁する。そのコントラストは、約１：５であり、反射電極上にＳｉＯからなる積層膜を形成しなかった場合の１：３．５から向上している。
【００１２】
液晶中には、カイラル成分、２色性色素、重合開始剤などが含まれていてもよい。液晶は、通常の液晶表示素子に使用されているものが好ましく使用できるが、散乱度を良好にするためには、液晶の複屈折率異方性、Δｎ、が０．１２以上、好ましくは０．１５以上が望ましい。また、アクティブ素子で駆動するためには、液晶単体の比抵抗は１×１０^９Ω・ｃｍ以上、さらに好ましくは２×１０^１１Ω・ｃｍ以上が、保持率を高く保ち表示品質を良好にするためには望ましい。
【００１３】
反射電極とする反射性部材は、Ａｌ、Ｃｒ、Ｍｇ、Ａｇ、Ａｕ、Ｐｔなどの金属単体、あるいは混合物などが好ましく、さらにはＡｌ、Ｃｒ、Ａｌ−Ｍｇ混合物が好ましく、特に安定性、反射率の点からＡｌ−Ｍｇ混合物が好ましい。Ｍｇの添加量は、０．１〜１０重量％が望ましく、特に０．５〜５重量％が安定性、反射率、操作性などの点から好ましい。反射性部材は、液晶高分子複合体と直接接する側に形成されてもよいし、基板を挟んで反対側に形成されてもよい。
【００１４】
反射電極の上に形成される積層膜は、ＳｉＯ、Ｍｇ_２Ｆ、ＳｉＯ_２、Ａｌ_２Ｏ_３、ＭｇＯ、Ｔａ_２Ｏ_５、ＺｎＯ、ＴｉＯ、ＣａＦ、ＡｌＦ_３、ＭｇＦ_２、ＣｅＯ_２、Ｇｅ、Ｃｕ、Ａｕ、ＺｎＳ−氷晶石などが挙げられる。それらの膜厚は、反射率を増加させたい光の波長をλ（μｍ）とすると、だいたいλ／２（μｍ）の厚さにすることが望ましい。
【００１５】
カイラル成分としては、通常のＴＮ、ＳＴＮ、ＦＴＮに使用されているＣＢ−１５、Ｃ−１５、Ｓ８１１、Ｓ１０８２（以上Ｍｅｒｃｋ社製）、ＣＭ−１９、ＣＭ、ＣＭ−２０、ＣＭ−２１、ＣＭ−２２（以上チッソ社製）などのものが好ましく使用される。その添加量は、０．０１〜１０重量％であり、好ましくは０．１〜５重量％である。０．０１重量％以下では効果が少なく、１０重量％以上では駆動電圧が高くなり、通常の素子では駆動が出来ない。
【００１６】
２色性色素としては通常のＧＨに使用されているアゾ系、アントラキノン系、ナフトキノン系、ペリレン系、キノフタロン系、アゾメチン系などが好ましく使用される。その中でも、耐光性の点からアントラキノン系単独、あるいは必要に応じて他の色素との混合したものが特に好ましい。これらの２色性色素は必要な色によって、適宜混合されて使用される。
【００１７】
高分子はリバース型ＰＤＬＣモードになるものならなんでもよいが、液晶素子製造の簡便性から紫外線硬化型モノマーが望ましい。紫外線硬化型モノマーとしては、単官能アクリレート、２官能アクリレートあるいは多官能アクリレートなどが好ましく使用される。散乱度を向上させるために、これらのモノマーは最低１個のベンゼン環をその分子構造中に含むことが望ましい。これらのモノマーには、カイラル性の成分を含むものでも良い。また、これらのモノマーは単独あるいは他のモノマー、オリゴマーと混合した後、紫外線を照射され高分子化されても良い。
【００１８】
本実施例では、ツイスト角が１８０度のリバース型ＰＤＬＣモードについて示したが、通常のＴＮモード、ＴＮモードに位相差板を組み合わせたもの、あるいはツイスト角度が１８０〜２７０度のＳＴＮモードおよびＳＴＮモードに位相差板を組み合わせたもの、ＧＨモードあるいはＧＨモードと位相差板を組み合わせたものでも同様の効果が期待できる。
【００１９】
また本実施例では、ＭＩＭ素子への応用について実施例を示したが、ラテラル型ＭＩＭ素子、バックトウバック型ＭＩＭ素子、バックトウバックラテラル型ＭＩＭ素子、スタティック駆動、時分割駆動、ＴＦＴ素子を使用した駆動でも同様の効果が期待できる。
【００２０】
（実施例２）
本実施例では、反射型リバースＰＤＬＣ液晶表示素子に反射電極上に積層膜を積層し反射率を向上させ、かつ液晶高分子複合体を挟んで反射板と反対側の基板には、特定の波長を選択的に透過反射する光学薄膜が液晶高分子複合体と接触するように積層されている場合について示す。
【００２１】
反射板と液晶高分子複合体を挟んで対向する透明電極上に、特定の波長を選択的に透過反射する光学薄膜を積層した。具体的には、ＴｉＯ_２からなる膜をｎｄ＝λ／４（ｎはＴｉＯ_２の屈折率、ｄは膜厚、λは希望する透過波長）になるように成膜した。それ以外は、全く実施例１と同様にして液晶表示素子を作製した。このようにして得られた液晶表示素子の電界が印加されていないときの断面の概略図を図３に示す。得られた液晶表示素子のコントラストは、１：４．５であり選択的に透過反射する光学薄膜がなかった場合より、コントラストは向上している。
【００２２】
液晶中には、カイラル成分、２色性色素、重合開始剤などが含まれていてもよい。液晶は、通常の液晶表示素子に使用されているものが好ましく使用できるが、散乱度を良好にするためには、液晶の複屈折率異方性、Δｎ、が０．１５以上、好ましくは０．１８以上さらに好ましくは０．２以上が望ましい。また、アクティブ素子で駆動するためには、液晶単体の比抵抗は１×１０^１０Ω・ｃｍ以上、さらに好ましくは２×１０^１２Ω・ｃｍ以上が保持率を高く保ち、表示品質を良好にするためには望ましい。
【００２３】
反射電極とする反射性部材は、Ａｌ、Ｃｒ、Ｍｇ、Ａｇ、Ａｕ、Ｐｔなどの金属単体、あるいは混合物などが好ましく、さらにはＡｌ、Ｃｒ、Ａｌ−Ｍｇ混合物が好ましく、特に安定性、反射率の点からＡｌ−Ｍｇ混合物が好ましい。
【００２４】
反射電極の上に形成される積層膜は、ＳｉＯ、Ｍｇ_２Ｆ、ＳｉＯ_２、Ａｌ_２Ｏ_３、ＭｇＯ、Ｔａ_２Ｏ_５、ＺｎＯ、ＴｉＯ、ＣａＦ、ＡｌＦ_３、ＭｇＦ_２、ＣｅＯ_２、Ｇｅ、Ｃｕ、Ａｕ、ＺｎＳ−氷晶石などが挙げられる。それらの膜厚は、反射率を増加させたい光の波長をλ（μｍ）とすると、だいたいλ／２（μｍ）の厚さにすることが望ましい。さらには、各画素が特定の波長をそれぞれ透過吸収するようにその厚さを制御しても良い。
【００２５】
カイラル成分としては、通常のＴＮ、ＳＴＮ、ＦＴＮに使用されているＣＢ−１５、Ｃ−１５、Ｓ８１１、Ｓ１０８２（以上Ｍｅｒｃｋ社製）、ＣＭ−１９、ＣＭ、ＣＭ−２０、ＣＭ−２１、ＣＭ−２２（以上チッソ社製）などのものが好ましく使用される。その添加量は、０．０１〜５ｗｔ％であり、好ましくは０．１〜２ｗｔ％である。
【００２６】
２色性色素としては通常のＧＨに使用されているアゾ系、アントラキノン系、ナフトキノン系、ペリレン系、キノフタロン系、アゾメチン系などが好ましく使用される。その中でも、耐光性の点からアントラキノン系が特に好ましい。これらの２色性色素は必要な色によって、適宜混合されて使用される。
【００２７】
高分子はリバース型ＰＤＬＣモードになるものならなんでもよいが、液晶素子製造の簡便性から紫外線硬化型モノマーが望ましい。紫外線硬化型モノマーとしては、単官能アクリレート、２官能アクリレートあるいは多官能アクリレートなどが好ましく使用される。散乱度を向上させるために、これらのモノマーは最低１個のベンゼン環をその分子構造中に含むことが望ましい。これらのモノマーには、カイラル性の成分を含むものでも良い。また、これらのモノマーは単独あるいは他のモノマー、オリゴマーと混合した後、紫外線を照射され高分子化されても良い。
【００２８】
本実施例では、ツイスト角が１８０度のリバース型ＰＤＬＣモードについて示したが、通常のＴＮモード、ＴＮモードに位相差板を組み合わせたもの、あるいはツイスト角度が１８０〜２７０度のＳＴＮモードおよびＳＴＮモードに位相差板を組み合わせたもの、ＧＨモードあるいはＧＨモードと位相差板を組み合わせたものでも同様の効果が期待できる。
【００２９】
また本実施例では、ＴＦＴ素子への応用について実施例を示したが、ＭＩＭ素子、ラテラル型ＭＩＭ素子、バックトウバック型ＭＩＭ素子、バックトウバックラテラル型ＭＩＭ素子、スタティック駆動、時分割駆動を使用した駆動でも同様の効果が期待できる。
【００３０】
（実施例３）
本実施例では、さらに基板を挟んで液晶高分子複合体と反対側に反射防止膜を形成した例を示す。液晶高分子複合体を挟んで反射電極と反対側になる基板の電極が形成されない面に、反射防止膜としてＭｇＦ_２をｎｄ＝λ／４（ｎはＭｇＦ_２の屈折率、ｄはその膜厚、λは反射を減少させたい中心波長）をほぼ満足するように成膜した。それ以外は実施例２と全く同様にして液晶表示素子を作製した。得られた液晶表示素子の電界が印加されていないときの断面の概略図を図４に示す。得られた液晶表示素子は、コントラストは変わらないものの、基板表面の反射、周囲の写り込みが低減されたため、表示されている文字、画像などが見やすいものとなった。
【００３１】
液晶中には、カイラル成分、２色性色素、重合開始剤などが含まれていてもよい。液晶は、通常の液晶表示素子に使用されているものが好ましく使用できるが、散乱度を良好にするためには、液晶の複屈折率異方性、Δｎ、が０．１５以上、好ましくは０．１８以上さらに好ましくは０．２以上が望ましい。また、アクティブ素子で駆動するためには、液晶単体の比抵抗は１×１０^１０Ω・ｃｍ以上、さらに好ましくは２×１０^１２Ω・ｃｍ以上が保持率を高く保ち、表示品質を良好にするためには望ましい。
【００３２】
反射電極とする反射性部材は、Ａｌ、Ｃｒ、Ｍｇ、Ａｇ、Ａｕ、Ｐｔなどの金属単体、あるいは混合物などが好ましく、さらにはＡｌ、Ｃｒ、Ａｌ−Ｍｇ混合物が好ましく、特に安定性、反射率の点からＡｌ−Ｍｇ混合物が好ましい。
【００３３】
カイラル成分としては、通常のＴＮ、ＳＴＮ、ＦＴＮに使用されているＣＢ−１５、Ｃ−１５、Ｓ８１１、Ｓ１０８２（以上Ｍｅｒｃｋ社製）、ＣＭ−１９、ＣＭ、ＣＭ−２０、ＣＭ−２１、ＣＭ−２２（以上チッソ社製）などのものが好ましく使用される。その添加量は、０．０１〜５ｗｔ％であり、好ましくは０．１〜２ｗｔ％である。
【００３４】
２色性色素としては通常のＧＨに使用されているアゾ系、アントラキノン系、ナフトキノン系、ペリレン系、キノフタロン系、アゾメチン系などが好ましく使用される。その中でも、耐光性の点からアントラキノン系が特に好ましい。これらの２色性色素は必要な色によって、適宜混合されて使用される。
【００３５】
高分子はリバース型ＰＤＬＣモードになるものならなんでもよいが、液晶素子製造の簡便性から紫外線硬化型モノマ−が望ましい。紫外線硬化型モノマ−としては、単官能アクリレ−ト、２官能アクリレ−トあるいは多官能アクリレ−トなどが好ましく使用される。散乱度を向上させるために、これらのモノマーは最低１個のベンゼン環をその分子構造中に含むことが望ましい。これらのモノマ−には、カイラル性の成分を含むものでも良い。また、これらのモノマーは単独あるいは他のモノマー、オリゴマーと混合した後、紫外線を照射され高分子化されても良い。
【００３６】
本実施例では、ツイスト角が１８０度のリバース型ＰＤＬＣモードについて示したが、通常のＴＮモード、ＴＮモードに位相差板を組み合わせたもの、あるいはツイスト角度が１８０〜２７０度のＳＴＮモードおよびＳＴＮモードに位相差板を組み合わせたもの、ＧＨモードあるいはＧＨモードと位相差板を組み合わせたものでも同様の効果が期待できる。
【００３７】
また本実施例では、ＴＦＴ素子への応用について実施例を示したが、ＭＩＭ素子、ラテラル型ＭＩＭ素子、バックトウバック型ＭＩＭ素子、バックトウバックラテラル型ＭＩＭ素子、スタティック駆動、時分割駆動を使用した駆動でも同様の効果が期待できる。
【００３８】
（実施例４）
本実施例では、開口率を向上させるために、素子上まで反射電極を形成した例を示す。基板上にＭＩＭ素子を形成した後、その上にアクリル樹脂からなる絶縁層を約２０００Åの厚さにスピンコートにより形成した。つぎに、素子と反射電極を接続するためにコンタクトホールを絶縁層に開けた後、Ａｌ−Ｍｇ合金（Ｍｇが３重量％）をスパッタにより２０００Åの厚さに形成し、反射電極とした。また、紫外線硬化形モノマーを、
【００３９】
【化２】

【００４０】
で表されるモノマーにした以外は、実施例１と全く同様にして液晶表示素子を作製した。得られた液晶表示素子の電界が印加されていないときの断面の概略図を図５に示す。得られた液晶表示素子は、開口率が向上したため、コントラストは１：７と実施例１のものより向上している。
【００４１】
液晶中には、カイラル成分、２色性色素、重合開始剤などが含まれていてもよい。液晶は、通常の液晶表示素子に使用されているものが好ましく使用できるが、散乱度を良好にするためには、液晶の複屈折率異方性、Δｎ、が０．１５以上、好ましくは０．１８以上さらに好ましくは０．２以上が望ましい。また、アクティブ素子で駆動するためには、液晶単体の比抵抗は１×１０^１０Ω・ｃｍ以上、さらに好ましくは２×１０^１２Ω・ｃｍ以上が保持率を高く保ち、表示品質を良好にするためには望ましい。
【００４２】
反射電極とする反射性部材は、Ａｌ、Ｃｒ、Ｍｇ、Ａｇ、Ａｕ、Ｐｔなどの金属単体、あるいは混合物などが好ましく、さらにはＡｌ、Ｃｒ、Ａｌ−Ｍｇ混合物が好ましく、特に安定性、反射率の点からＡｌ−Ｍｇ混合物が好ましい。
【００４３】
カイラル成分としては、通常のＴＮ、ＳＴＮ、ＦＴＮに使用されているＣＢ−１５、Ｃ−１５、Ｓ８１１、Ｓ１０８２（以上Ｍｅｒｃｋ社製）、ＣＭ−１９、ＣＭ、ＣＭ−２０、ＣＭ−２１、ＣＭ−２２（以上チッソ社製）などのものが好ましく使用される。その添加量は、０．０１〜５ｗｔ％であり、好ましくは０．１〜２ｗｔ％である。
【００４４】
２色性色素としては通常のＧＨに使用されているアゾ系、アントラキノン系、ナフトキノン系、ペリレン系、キノフタロン系、アゾメチン系などが好ましく使用される。その中でも、耐光性の点からアントラキノン系が特に好ましい。これらの２色性色素は必要な色によって、適宜混合されて使用される。
【００４５】
高分子はリバース型ＰＤＬＣモードになるものならなんでもよいが、液晶素子製造の簡便性から紫外線硬化型モノマ−が望ましい。紫外線硬化型モノマ−としては、単官能アクリレ−ト、２官能アクリレ−トあるいは多官能アクリレ−トなどが好ましく使用される。散乱度を向上させるために、これらのモノマーは最低１個のベンゼン環をその分子構造中に含むことが望ましい。これらのモノマ−には、カイラル性の成分を含むものでも良い。また、これらのモノマーは単独あるいは他のモノマー、オリゴマーと混合した後、紫外線を照射され高分子化されても良い。
【００４６】
本実施例では、ツイスト角が１８０度のリバース型ＰＤＬＣモードについて示したが、通常のＴＮモード、ＴＮモードに位相差板を組み合わせたもの、あるいはツイスト角度が１８０〜２７０度のＳＴＮモードおよびＳＴＮモードに位相差板を組み合わせたもの、ＧＨモードあるいはＧＨモードと位相差板を組み合わせたものでも同様の効果が期待できる。
【００４７】
また本実施例では、ＴＦＴ素子への応用について実施例を示したが、ＭＩＭ素子、ラテラル型ＭＩＭ素子、バックトウバック型ＭＩＭ素子、バックトウバックラテラル型ＭＩＭ素子、スタティック駆動、時分割駆動を使用した駆動でも同様の効果が期待できる。
【００４８】
【発明の効果】
以上説明したように、本発明による各種の光学薄膜と液晶高分子複合体からなる液晶セルを組み合わせることにより、見やすく、コントラストが改良された液晶表示素子が製造できるようになった。
【図面の簡単な説明】
【図１】反射型リバースＰＤＬＣの概略を示す図。
【図２】反射電極上に、反射率を増加させる積層膜を形成した液晶表示素子の電界無印加時の概略断面図。。
【図３】反射率増加膜と、特定波長を選択的に透過反射する光学薄膜を積層した液晶表示素子の電界無印加時の概略断面図。
【図４】反射増加膜、選択的透過反射光学薄膜、反射防止膜を形成した液晶表示素子の電界無印加時の概略断面図。
【図５】開口率を向上するために、素子上にまで反射電極を形成した液晶表示素子の断面の概略図。
【符号の説明】
１−１ 入射光
１−２ 反射光
１−３ 基板
１−４ 電極
１−５ 配向膜
１−６ 液晶
１−７ 高分子
１−８ 入射光の光路
１−９ 反射性の部材
１−１０ ２端子あるいは３端子素子
１−１１ 絶縁材
１−１２ コンタクトホール
２−１ 反射率を増加させる積層膜
３−１ 特定波長を選択的に透過反射する光学薄膜
４−１ 反射防止膜[0001]
[Industrial applications]
The present invention relates to a display element applied to a display, various display elements, a projector, and the like, and further relates to a structure of a display using the same.
[0002]
[Prior art]
Conventionally, a display device using liquid crystal has been developed as a lightweight and thin display device. In particular, in recent years, a display device has been attracting particular attention, in which a nematic liquid crystal is sandwiched between two substrates and aligned, and a response when an electric field is applied is detected via a polarizing plate. However, since such a display device uses a polarizing plate, the display is dark because light is almost absorbed by the polarizing plate. Therefore, in recent years, a liquid crystal display device using light scattering has been developed as a display device using no polarizing plate (as shown in U.S. Pat. Nos. 3600060, 4688900, 4891152, 481070). In these liquid crystal display devices, liquid crystals exist as isolated droplets in a polymer matrix, and when no voltage is applied, light is absorbed or scattered. Are arranged in a light transmitting state. Therefore, these display devices have been studied mainly for the transmission type, but since the contrast is not enough for practical use, in order to improve this, the applicant has used a new display mode as the reflection type. (Japanese Patent Application Nos. 2-309316 and 3-13268). A new display mode is a mixture of liquid crystal and liquid crystalline particles or needle-shaped polymers that have been subjected to alignment treatment.The display mode is a light transmission state when no voltage is applied, and a light scattering state when a voltage is applied. It becomes.
[0003]
[Problems to be solved by the invention]
However, even in the above-mentioned reflective display element, satisfactory contrast and brightness have not yet been obtained because the utilization efficiency of incident light is still low. 2. Description of the Related Art A general liquid crystal display device enables display by applying an electric field to a liquid crystal layer sandwiched between a pair of opposed electrodes such as a so-called common electrode and a segment electrode. However, in order to form a plurality of electrode wires on a substrate without short-circuiting, a gap of about several μm or an insulating layer is usually formed between the electrode wires and the adjacent electrode wires. Therefore, no electric field is applied to the gap or the liquid crystal layer in contact with the insulating layer, and the liquid crystal layer is not involved in display. As described above, the ratio of the remaining portion excluding the portion that is not involved in the display because the electric field is not applied to the entire substrate area is usually called the aperture ratio. 2. Description of the Related Art In recent years, as the definition of display elements has advanced and the number of pixels, that is, the number of electrode lines has increased, the aperture ratio has relatively decreased, and the display image quality has become dark. In the case of a liquid crystal display using a so-called active element typified by a TFT or MIM, the degree of reduction was more remarkable than in the case of a liquid crystal display typified by a simple matrix. Also, in a transmissive display element, the decrease in brightness due to a decrease in the aperture ratio can be compensated for by increasing the amount of light of the backlight, but in the case of a reflective type, only ambient light is used. The problem of reduced brightness was very pronounced and serious.
[0004]
In order to solve these problems, there is a method of using a reflection type liquid crystal display device. That is, a method of forming a counter electrode or a pixel electrode, which is usually made of a transparent electrode, with a reflective member. However, this alone is not enough to improve the display quality, and further improvement has been desired.
[0005]
[Means for Solving the Problems]
In the liquid crystal electro-optical element according to the present invention, in a liquid crystal electro-optical element in which two substrates are arranged to face each other and a reflective member is formed on one of the two substrates, the reflective member is provided on the reflective member. An optical thin film is laminated, and the optical thin film is laminated with a film thickness of approximately λ / 2 with respect to a predetermined light wavelength λ, and the wavelength λ of the laminate of the reflective member and the optical thin film is formed. Is higher than the reflectance for the wavelength λ of the reflective member, an anti-reflection film is disposed on the other one of the two substrates, and the anti-reflection film is The reflective member is provided with a film thickness of approximately λ / 4 with respect to λ , and the reflective member is made of an Al-Mg mixture .
The optical thin film is made of SiO, Mg ₂ F, SiO ₂ , Al ₂ O ₃ , MgO, Ta ₂ O ₅ , ZnO, TiO, CaF, AlF ₃ , TiO ₂ , MgF ₂ , CeO ₂ , Ge, Cu, Au, It is characterized by including a thin film selected from the group consisting of ZnS and cryolite.
The liquid crystal electro-optical element is of a reverse PDLC mode, TN mode, or STN mode.
[0006]
【Example】
(Example 1)
In this embodiment, a case will be described in which a reflective reverse PDLC liquid crystal display element is laminated with a laminated film on a reflective electrode to improve the reflectance. Reverse PDLC is a mixture of liquid crystal and polymer, and if necessary, dichroic dye. When no voltage is applied, the alignment state of liquid crystal and polymer is the same, so that the incident light is not scattered and there is a transparent state and dichroic dye is present. If so, it is in a colored state due to absorption of the dichroic dye. In addition, when a voltage is applied, the liquid crystal and the dichroic dye are oriented in the direction of the electric field, so that the incident light is scattered, and the liquid crystal and the dichroic dye become turbid.
[0007]
FIG. 1 shows a typical sectional view. FIG. 1 shows a case where an electric field is applied to the pixel electrode. When an electric field is applied to the pixel electrode, liquid crystal molecules in a range where the electric field acts are oriented in the direction of the electric field, and accordingly, the dichroic dye is also oriented in the direction of the electric field. Therefore, the display state of the pixel changes from a colored state due to absorption of the dichroic dye when no electric field is applied to a cloudy state scattered due to a mismatch between the refractive indexes of the liquid crystal and the polymer. In other words, if the dichroic dye is blended so as to absorb almost all wavelengths, black and white when an electric field is not applied and white when an electric field is applied can be displayed without a polarizing plate. .
[0008]
The pixel electrode of the MIM element was a transparent electrode, the counter electrode was a reflective electrode, and the reflective electrode was formed by sputtering an Al-Mg (3% by weight of Mg) alloy to a thickness of 2000 mm. Further, a laminated film made of SiO was formed on the reflective electrode by sputtering so that the film thickness became about 0.27 μm. After applying an aligning agent to the element substrate having the MIM element and the counter substrate having the counter electrode, a rubbing treatment is performed so that the twist angle becomes 180 degrees, and the substrates are bonded together via a sealant to form a liquid crystal cell having a cell thickness of 10 μm. Was. In this gap, the liquid crystal TL-202 (manufactured by Merck)
[0009]
Embedded image

[0010]
Was mixed in a liquid crystal: monomer = 95: 5 (weight ratio) and sealed in a panel under vacuum. Further, in order to make the monomer into a polymer, the enclosed panel was irradiated with ultraviolet rays for 15 minutes under an atmosphere of 40 degrees such that the total irradiation amount was 500 mJ / cm ² . FIG. 2 is a schematic cross-sectional view of the liquid crystal display device obtained in this manner when no electric field is applied.
[0011]
The liquid crystal display element thus obtained is substantially transparent and transmits light when no voltage is applied, and the pixel portion is mirror-shaped. It becomes cloudy when voltage is applied. The contrast is about 1: 5, which is improved from 1: 3.5 when the laminated film made of SiO is not formed on the reflective electrode.
[0012]
The liquid crystal may contain a chiral component, a dichroic dye, a polymerization initiator, and the like. As the liquid crystal, those used in ordinary liquid crystal display elements can be preferably used, but in order to improve the degree of scattering, the birefringence anisotropy and Δn of the liquid crystal are 0.12 or more, preferably 0. .15 or more is desirable. In order to drive with an active element, the specific resistance of the liquid crystal alone is 1 × 10 ⁹ Ω · cm or more, more preferably 2 × 10 ¹¹ Ω · cm or more, and the retention rate is kept high to improve the display quality. Desirable for.
[0013]
The reflective member used as the reflective electrode is preferably a single metal such as Al, Cr, Mg, Ag, Au, or Pt, or a mixture thereof, and more preferably a mixture of Al, Cr, and Al—Mg. In view of this, an Al-Mg mixture is preferable. The addition amount of Mg is desirably 0.1 to 10% by weight, and particularly preferably 0.5 to 5% by weight in terms of stability, reflectance, operability, and the like. The reflective member may be formed on the side directly in contact with the liquid crystal polymer composite, or may be formed on the opposite side across the substrate.
[0014]
The laminated film formed on the reflection electrode includes SiO, Mg ₂ F, SiO ₂ , Al ₂ O ₃ , MgO, Ta ₂ O ₅ , ZnO, TiO, CaF, AlF ₃ , MgF ₂ , CeO ₂ , Ge, Cu, Au, ZnS-cryolite, and the like. It is desirable that the film thickness be about λ / 2 (μm), where λ (μm) is the wavelength of light whose reflectance is to be increased.
[0015]
Examples of the chiral component include CB-15, C-15, S811, S1082 (manufactured by Merck), CM-19, CM, CM-20, CM-21, and CM used in ordinary TN, STN, and FTN. -22 (all manufactured by Chisso Corporation) and the like are preferably used. The addition amount is 0.01 to 10% by weight, preferably 0.1 to 5% by weight. When the content is 0.01% by weight or less, the effect is small, and when the content is 10% by weight or more, the driving voltage becomes high, and the ordinary element cannot be driven.
[0016]
As the dichroic dye, azo-based, anthraquinone-based, naphthoquinone-based, perylene-based, quinophthalone-based, and azomethine-based dyes used in ordinary GH are preferably used. Among them, from the viewpoint of light resistance, an anthraquinone compound alone or, if necessary, a mixture with another dye is particularly preferable. These dichroic dyes are appropriately mixed and used depending on the required color.
[0017]
Any polymer can be used as long as it can be in the reverse PDLC mode, but an ultraviolet curable monomer is desirable from the viewpoint of simplicity in manufacturing a liquid crystal device. As the UV-curable monomer, a monofunctional acrylate, a difunctional acrylate, a polyfunctional acrylate, or the like is preferably used. In order to improve the degree of scattering, these monomers preferably contain at least one benzene ring in the molecular structure. These monomers may contain a chiral component. In addition, these monomers may be polymerized by irradiating ultraviolet rays alone or after mixing with other monomers or oligomers.
[0018]
In the present embodiment, the reverse type PDLC mode with a twist angle of 180 degrees has been described. The same effect can be expected even if the phase difference plate is combined with the GH mode or the combination of the GH mode and the phase difference plate.
[0019]
In this embodiment, the application to the MIM element has been described. However, a lateral MIM element, a back-to-back MIM element, a back-to-back lateral MIM element, a static drive, a time division drive, and a TFT element are used. The same effect can be expected even with the drive performed.
[0020]
(Example 2)
In the present embodiment, a reflective reverse PDLC liquid crystal display element is laminated with a laminated film on a reflective electrode to improve the reflectance, and a specific wavelength is provided on a substrate on the opposite side of the reflective plate with the liquid crystal polymer composite therebetween. Is shown in the case where the optical thin film selectively transmitting and reflecting is laminated so as to come into contact with the liquid crystal polymer composite.
[0021]
An optical thin film that selectively transmits and reflects a specific wavelength was laminated on a transparent electrode facing the reflection plate with the liquid crystal polymer composite therebetween. Specifically, a film made of TiO ₂ was formed so that nd = λ / 4 (n is the refractive index of TiO ₂ , d is the film thickness, and λ is a desired transmission wavelength). Except for this, a liquid crystal display device was manufactured in the same manner as in Example 1. FIG. 3 is a schematic cross-sectional view of the liquid crystal display device obtained in this manner when no electric field is applied. The contrast of the obtained liquid crystal display device is 1: 4.5, which is higher than that in the case where there is no optical thin film that selectively transmits and reflects.
[0022]
The liquid crystal may contain a chiral component, a dichroic dye, a polymerization initiator, and the like. As the liquid crystal, those used in ordinary liquid crystal display elements can be preferably used. However, in order to improve the degree of scattering, the birefringence anisotropy and Δn of the liquid crystal are 0.15 or more, preferably 0. .18 or more, more preferably 0.2 or more. In order to drive with an active element, the specific resistance of the liquid crystal alone is 1 × 10 ¹⁰ Ω · cm or more, more preferably 2 × 10 ¹² Ω · cm or more, and the retention rate is kept high to improve the display quality. Desirable for.
[0023]
The reflective member used as the reflective electrode is preferably a single metal such as Al, Cr, Mg, Ag, Au, or Pt, or a mixture thereof, and more preferably a mixture of Al, Cr, and Al—Mg. In view of this, an Al-Mg mixture is preferable.
[0024]
The laminated film formed on the reflection electrode includes SiO, Mg ₂ F, SiO ₂ , Al ₂ O ₃ , MgO, Ta ₂ O ₅ , ZnO, TiO, CaF, AlF ₃ , MgF ₂ , CeO ₂ , Ge, Cu, Au, ZnS-cryolite, and the like. It is desirable that the film thickness be about λ / 2 (μm), where λ (μm) is the wavelength of light whose reflectance is to be increased. Further, the thickness may be controlled so that each pixel transmits and absorbs a specific wavelength.
[0025]
Examples of the chiral component include CB-15, C-15, S811, S1082 (manufactured by Merck), CM-19, CM, CM-20, CM-21, and CM used in ordinary TN, STN, and FTN. -22 (all manufactured by Chisso Corporation) and the like are preferably used. The addition amount is 0.01 to 5 wt%, preferably 0.1 to 2 wt%.
[0026]
As the dichroic dye, azo-based, anthraquinone-based, naphthoquinone-based, perylene-based, quinophthalone-based, and azomethine-based dyes used in ordinary GH are preferably used. Among them, anthraquinones are particularly preferable from the viewpoint of light resistance. These dichroic dyes are appropriately mixed and used depending on the required color.
[0027]
Any polymer can be used as long as it can be in the reverse PDLC mode, but an ultraviolet curable monomer is desirable from the viewpoint of simplicity in manufacturing a liquid crystal device. As the UV-curable monomer, a monofunctional acrylate, a difunctional acrylate, a polyfunctional acrylate, or the like is preferably used. In order to improve the degree of scattering, these monomers preferably contain at least one benzene ring in the molecular structure. These monomers may contain a chiral component. In addition, these monomers may be polymerized by irradiating ultraviolet rays alone or after mixing with other monomers or oligomers.
[0028]
In this embodiment, the reverse type PDLC mode having a twist angle of 180 degrees has been described. However, a normal TN mode, a combination of a TN mode and a retardation plate, or an STN mode and an STN mode having a twist angle of 180 to 270 degrees are used. The same effect can be expected even if the phase difference plate is combined with the GH mode or the combination of the GH mode and the phase difference plate.
[0029]
Further, in this embodiment, the embodiment is applied to the TFT element. However, the MIM element, the lateral MIM element, the back-to-back MIM element, the back-to-back lateral MIM element, the static driving, and the time-division driving are used. The same effect can be expected even with the drive performed.
[0030]
(Example 3)
In this embodiment, an example is shown in which an antireflection film is further formed on the opposite side of the liquid crystal polymer composite with the substrate interposed therebetween. On a surface substrate of the electrode is not formed to be opposite to the reflective electrodes sandwiching the liquid crystal polymer composite, the MgF ₂ as an anti-reflection film nd = λ / 4 (n is the refractive index of MgF _2, d is a thickness , Λ is the center wavelength at which reflection is to be reduced). Except for this, a liquid crystal display device was manufactured in exactly the same manner as in Example 2. FIG. 4 is a schematic cross-sectional view of the obtained liquid crystal display element when no electric field is applied. Although the obtained liquid crystal display element had the same contrast, reflection of the substrate surface and reflection of the surroundings were reduced, so that displayed characters and images were easy to see.
[0031]
The liquid crystal may contain a chiral component, a dichroic dye, a polymerization initiator, and the like. As the liquid crystal, those used in ordinary liquid crystal display elements can be preferably used. However, in order to improve the degree of scattering, the birefringence anisotropy and Δn of the liquid crystal are 0.15 or more, preferably 0. .18 or more, more preferably 0.2 or more. In order to drive with an active element, the specific resistance of the liquid crystal alone is 1 × 10 ¹⁰ Ω · cm or more, more preferably 2 × 10 ¹² Ω · cm or more, and the retention rate is kept high to improve the display quality. Desirable for.
[0032]
The reflective member used as the reflective electrode is preferably a single metal such as Al, Cr, Mg, Ag, Au, or Pt, or a mixture thereof, and more preferably a mixture of Al, Cr, and Al—Mg. In view of this, an Al-Mg mixture is preferable.
[0033]
Examples of the chiral component include CB-15, C-15, S811, S1082 (manufactured by Merck), CM-19, CM, CM-20, CM-21, and CM used in ordinary TN, STN, and FTN. -22 (all manufactured by Chisso Corporation) and the like are preferably used. The addition amount is 0.01 to 5 wt%, preferably 0.1 to 2 wt%.
[0034]
As the dichroic dye, azo-based, anthraquinone-based, naphthoquinone-based, perylene-based, quinophthalone-based, and azomethine-based dyes used in ordinary GH are preferably used. Among them, anthraquinones are particularly preferable from the viewpoint of light resistance. These dichroic dyes are appropriately mixed and used depending on the required color.
[0035]
Any polymer can be used as long as it is a reverse type PDLC mode, but an ultraviolet curable monomer is desirable from the viewpoint of convenience in manufacturing a liquid crystal element. As the UV-curable monomer, a monofunctional acrylate, a bifunctional acrylate or a polyfunctional acrylate is preferably used. In order to improve the degree of scattering, these monomers preferably contain at least one benzene ring in the molecular structure. These monomers may contain a chiral component. In addition, these monomers may be polymerized by irradiating ultraviolet rays alone or after mixing with other monomers or oligomers.
[0036]
In this embodiment, the reverse type PDLC mode having a twist angle of 180 degrees has been described. However, a normal TN mode, a combination of a TN mode and a retardation plate, or an STN mode and an STN mode having a twist angle of 180 to 270 degrees are used. The same effect can be expected even if the phase difference plate is combined with the GH mode or the combination of the GH mode and the phase difference plate.
[0037]
Further, in this embodiment, the embodiment is applied to the TFT element. However, the MIM element, the lateral MIM element, the back-to-back MIM element, the back-to-back lateral MIM element, the static driving, and the time-division driving are used. The same effect can be expected even with the drive performed.
[0038]
(Example 4)
In this embodiment, an example is shown in which a reflective electrode is formed up to an element in order to improve the aperture ratio. After forming the MIM element on the substrate, an insulating layer made of an acrylic resin was formed thereon by spin coating to a thickness of about 2000 mm. Next, after a contact hole was opened in the insulating layer to connect the element and the reflective electrode, an Al—Mg alloy (3% by weight of Mg) was formed to a thickness of 2000 mm by sputtering to obtain a reflective electrode. In addition, UV-curable monomers
[0039]
Embedded image

[0040]
A liquid crystal display device was produced in exactly the same manner as in Example 1, except that the monomer represented by the formula was used. FIG. 5 is a schematic cross-sectional view of the obtained liquid crystal display element when no electric field is applied. The contrast of the obtained liquid crystal display element was 1: 7, which is higher than that of Example 1, because the aperture ratio was improved.
[0041]
The liquid crystal may contain a chiral component, a dichroic dye, a polymerization initiator, and the like. As the liquid crystal, those used in ordinary liquid crystal display elements can be preferably used. However, in order to improve the degree of scattering, the birefringence anisotropy and Δn of the liquid crystal are 0.15 or more, preferably 0. .18 or more, more preferably 0.2 or more. In order to drive with an active element, the specific resistance of the liquid crystal alone is 1 × 10 ¹⁰ Ω · cm or more, more preferably 2 × 10 ¹² Ω · cm or more, and the retention rate is kept high to improve the display quality. Desirable for.
[0042]
The reflective member used as the reflective electrode is preferably a single metal such as Al, Cr, Mg, Ag, Au, or Pt, or a mixture thereof, and more preferably a mixture of Al, Cr, and Al—Mg. In view of this, an Al-Mg mixture is preferable.
[0043]
Examples of the chiral component include CB-15, C-15, S811, S1082 (manufactured by Merck), CM-19, CM, CM-20, CM-21, and CM used in ordinary TN, STN, and FTN. -22 (all manufactured by Chisso Corporation) and the like are preferably used. The addition amount is 0.01 to 5 wt%, preferably 0.1 to 2 wt%.
[0044]
As the dichroic dye, azo-based, anthraquinone-based, naphthoquinone-based, perylene-based, quinophthalone-based, and azomethine-based dyes used in ordinary GH are preferably used. Among them, anthraquinones are particularly preferable from the viewpoint of light resistance. These dichroic dyes are appropriately mixed and used depending on the required color.
[0045]
Any polymer can be used as long as it is a reverse type PDLC mode, but an ultraviolet curable monomer is desirable from the viewpoint of convenience in manufacturing a liquid crystal element. As the UV-curable monomer, a monofunctional acrylate, a bifunctional acrylate or a polyfunctional acrylate is preferably used. In order to improve the degree of scattering, these monomers preferably contain at least one benzene ring in the molecular structure. These monomers may contain a chiral component. In addition, these monomers may be polymerized by irradiating ultraviolet rays alone or after mixing with other monomers or oligomers.
[0046]
In the present embodiment, the reverse type PDLC mode with a twist angle of 180 degrees has been described. The same effect can be expected even if the phase difference plate is combined with the GH mode or the combination of the GH mode and the phase difference plate.
[0047]
Further, in this embodiment, the embodiment is applied to the TFT element. However, the MIM element, the lateral MIM element, the back-to-back MIM element, the back-to-back lateral MIM element, the static driving, and the time-division driving are used. The same effect can be expected even with the drive performed.
[0048]
【The invention's effect】
As described above, by combining various optical thin films according to the present invention and a liquid crystal cell composed of a liquid crystal polymer composite, a liquid crystal display device with improved visibility and improved contrast can be manufactured.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a reflection type reverse PDLC.
FIG. 2 is a schematic cross-sectional view of a liquid crystal display element in which a laminated film for increasing reflectivity is formed on a reflective electrode when no electric field is applied. .
FIG. 3 is a schematic cross-sectional view of a liquid crystal display element in which a reflectance increasing film and an optical thin film that selectively transmits and reflects a specific wavelength are stacked, when no electric field is applied.
FIG. 4 is a schematic cross-sectional view of a liquid crystal display device on which a reflection enhancement film, a selective transmission / reflection optical thin film, and an antireflection film are formed, when no electric field is applied.
FIG. 5 is a schematic cross-sectional view of a liquid crystal display device in which a reflective electrode is formed on the device in order to improve the aperture ratio.
[Explanation of symbols]
1-1 Incident light 1-2 Reflected light 1-3 Substrate 1-4 Electrode 1-5 Alignment film 1-6 Liquid crystal 1-7 Polymer 1-8 Optical path of incident light 1-9 Reflective member 1-10 2 Terminal or three-terminal element 1-11 Insulating material 1-12 Contact hole 2-1 Laminated film 3-1 that increases reflectivity Optical thin film 4-1 that selectively transmits and reflects a specific wavelength 4-1 Antireflection film

Claims (3)

In a liquid crystal electro-optical element in which two substrates are arranged to face each other and a reflective member is formed on one of the two substrates,
An optical thin film is laminated on the reflective member,
The optical thin film is laminated with a thickness of approximately λ / 2 with respect to a predetermined wavelength λ of light,
The reflectance for the wavelength λ of the laminate of the reflective member and the optical thin film is higher than the reflectance for the wavelength λ of the reflective member,
An anti-reflection film is provided on the other one of the two substrates,
The antireflection film is disposed with a thickness of approximately λ / 4 with respect to the wavelength λ ,
The liquid crystal electro-optical element according to claim 1, wherein the reflective member is made of an Al-Mg mixture . The optical thin film is made of SiO, Mg ₂ F, SiO ₂ , Al ₂ O ₃ , MgO, Ta ₂ O ₅ , ZnO, TiO, CaF, AlF ₃ , TiO ₂ , MgF ₂ , CeO ₂ , Ge, Cu, Au, 2. The liquid crystal electro-optical device according to claim 1, comprising a thin film selected from the group consisting of ZnS and cryolite. 3. The liquid crystal electro-optical element according to claim 1, wherein the liquid crystal electro-optical element is a reverse PDLC mode, a TN mode, or an STN mode.

Images